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1 | /* Global common subexpression elimination/Partial redundancy elimination | |
2 | and global constant/copy propagation for GNU compiler. | |
3 | Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002 | |
4 | Free Software Foundation, Inc. | |
5 | ||
6 | This file is part of GCC. | |
7 | ||
8 | GCC is free software; you can redistribute it and/or modify it under | |
9 | the terms of the GNU General Public License as published by the Free | |
10 | Software Foundation; either version 2, or (at your option) any later | |
11 | version. | |
12 | ||
13 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
14 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
15 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
16 | for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with GCC; see the file COPYING. If not, write to the Free | |
20 | Software Foundation, 59 Temple Place - Suite 330, Boston, MA | |
21 | 02111-1307, USA. */ | |
22 | ||
23 | /* TODO | |
24 | - reordering of memory allocation and freeing to be more space efficient | |
25 | - do rough calc of how many regs are needed in each block, and a rough | |
26 | calc of how many regs are available in each class and use that to | |
27 | throttle back the code in cases where RTX_COST is minimal. | |
28 | - a store to the same address as a load does not kill the load if the | |
29 | source of the store is also the destination of the load. Handling this | |
30 | allows more load motion, particularly out of loops. | |
31 | - ability to realloc sbitmap vectors would allow one initial computation | |
32 | of reg_set_in_block with only subsequent additions, rather than | |
33 | recomputing it for each pass | |
34 | ||
35 | */ | |
36 | ||
37 | /* References searched while implementing this. | |
38 | ||
39 | Compilers Principles, Techniques and Tools | |
40 | Aho, Sethi, Ullman | |
41 | Addison-Wesley, 1988 | |
42 | ||
43 | Global Optimization by Suppression of Partial Redundancies | |
44 | E. Morel, C. Renvoise | |
45 | communications of the acm, Vol. 22, Num. 2, Feb. 1979 | |
46 | ||
47 | A Portable Machine-Independent Global Optimizer - Design and Measurements | |
48 | Frederick Chow | |
49 | Stanford Ph.D. thesis, Dec. 1983 | |
50 | ||
51 | A Fast Algorithm for Code Movement Optimization | |
52 | D.M. Dhamdhere | |
53 | SIGPLAN Notices, Vol. 23, Num. 10, Oct. 1988 | |
54 | ||
55 | A Solution to a Problem with Morel and Renvoise's | |
56 | Global Optimization by Suppression of Partial Redundancies | |
57 | K-H Drechsler, M.P. Stadel | |
58 | ACM TOPLAS, Vol. 10, Num. 4, Oct. 1988 | |
59 | ||
60 | Practical Adaptation of the Global Optimization | |
61 | Algorithm of Morel and Renvoise | |
62 | D.M. Dhamdhere | |
63 | ACM TOPLAS, Vol. 13, Num. 2. Apr. 1991 | |
64 | ||
65 | Efficiently Computing Static Single Assignment Form and the Control | |
66 | Dependence Graph | |
67 | R. Cytron, J. Ferrante, B.K. Rosen, M.N. Wegman, and F.K. Zadeck | |
68 | ACM TOPLAS, Vol. 13, Num. 4, Oct. 1991 | |
69 | ||
70 | Lazy Code Motion | |
71 | J. Knoop, O. Ruthing, B. Steffen | |
72 | ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI | |
73 | ||
74 | What's In a Region? Or Computing Control Dependence Regions in Near-Linear | |
75 | Time for Reducible Flow Control | |
76 | Thomas Ball | |
77 | ACM Letters on Programming Languages and Systems, | |
78 | Vol. 2, Num. 1-4, Mar-Dec 1993 | |
79 | ||
80 | An Efficient Representation for Sparse Sets | |
81 | Preston Briggs, Linda Torczon | |
82 | ACM Letters on Programming Languages and Systems, | |
83 | Vol. 2, Num. 1-4, Mar-Dec 1993 | |
84 | ||
85 | A Variation of Knoop, Ruthing, and Steffen's Lazy Code Motion | |
86 | K-H Drechsler, M.P. Stadel | |
87 | ACM SIGPLAN Notices, Vol. 28, Num. 5, May 1993 | |
88 | ||
89 | Partial Dead Code Elimination | |
90 | J. Knoop, O. Ruthing, B. Steffen | |
91 | ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994 | |
92 | ||
93 | Effective Partial Redundancy Elimination | |
94 | P. Briggs, K.D. Cooper | |
95 | ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994 | |
96 | ||
97 | The Program Structure Tree: Computing Control Regions in Linear Time | |
98 | R. Johnson, D. Pearson, K. Pingali | |
99 | ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994 | |
100 | ||
101 | Optimal Code Motion: Theory and Practice | |
102 | J. Knoop, O. Ruthing, B. Steffen | |
103 | ACM TOPLAS, Vol. 16, Num. 4, Jul. 1994 | |
104 | ||
105 | The power of assignment motion | |
106 | J. Knoop, O. Ruthing, B. Steffen | |
107 | ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI | |
108 | ||
109 | Global code motion / global value numbering | |
110 | C. Click | |
111 | ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI | |
112 | ||
113 | Value Driven Redundancy Elimination | |
114 | L.T. Simpson | |
115 | Rice University Ph.D. thesis, Apr. 1996 | |
116 | ||
117 | Value Numbering | |
118 | L.T. Simpson | |
119 | Massively Scalar Compiler Project, Rice University, Sep. 1996 | |
120 | ||
121 | High Performance Compilers for Parallel Computing | |
122 | Michael Wolfe | |
123 | Addison-Wesley, 1996 | |
124 | ||
125 | Advanced Compiler Design and Implementation | |
126 | Steven Muchnick | |
127 | Morgan Kaufmann, 1997 | |
128 | ||
129 | Building an Optimizing Compiler | |
130 | Robert Morgan | |
131 | Digital Press, 1998 | |
132 | ||
133 | People wishing to speed up the code here should read: | |
134 | Elimination Algorithms for Data Flow Analysis | |
135 | B.G. Ryder, M.C. Paull | |
136 | ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986 | |
137 | ||
138 | How to Analyze Large Programs Efficiently and Informatively | |
139 | D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck | |
140 | ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI | |
141 | ||
142 | People wishing to do something different can find various possibilities | |
143 | in the above papers and elsewhere. | |
144 | */ | |
145 | ||
146 | #include "config.h" | |
147 | #include "system.h" | |
148 | #include "toplev.h" | |
149 | ||
150 | #include "rtl.h" | |
151 | #include "tm_p.h" | |
152 | #include "regs.h" | |
153 | #include "hard-reg-set.h" | |
154 | #include "flags.h" | |
155 | #include "real.h" | |
156 | #include "insn-config.h" | |
157 | #include "recog.h" | |
158 | #include "basic-block.h" | |
159 | #include "output.h" | |
160 | #include "function.h" | |
161 | #include "expr.h" | |
162 | #include "except.h" | |
163 | #include "ggc.h" | |
164 | #include "params.h" | |
165 | #include "cselib.h" | |
166 | ||
167 | #include "obstack.h" | |
168 | ||
169 | /* Propagate flow information through back edges and thus enable PRE's | |
170 | moving loop invariant calculations out of loops. | |
171 | ||
172 | Originally this tended to create worse overall code, but several | |
173 | improvements during the development of PRE seem to have made following | |
174 | back edges generally a win. | |
175 | ||
176 | Note much of the loop invariant code motion done here would normally | |
177 | be done by loop.c, which has more heuristics for when to move invariants | |
178 | out of loops. At some point we might need to move some of those | |
179 | heuristics into gcse.c. */ | |
180 | ||
181 | /* We support GCSE via Partial Redundancy Elimination. PRE optimizations | |
182 | are a superset of those done by GCSE. | |
183 | ||
184 | We perform the following steps: | |
185 | ||
186 | 1) Compute basic block information. | |
187 | ||
188 | 2) Compute table of places where registers are set. | |
189 | ||
190 | 3) Perform copy/constant propagation. | |
191 | ||
192 | 4) Perform global cse. | |
193 | ||
194 | 5) Perform another pass of copy/constant propagation. | |
195 | ||
196 | Two passes of copy/constant propagation are done because the first one | |
197 | enables more GCSE and the second one helps to clean up the copies that | |
198 | GCSE creates. This is needed more for PRE than for Classic because Classic | |
199 | GCSE will try to use an existing register containing the common | |
200 | subexpression rather than create a new one. This is harder to do for PRE | |
201 | because of the code motion (which Classic GCSE doesn't do). | |
202 | ||
203 | Expressions we are interested in GCSE-ing are of the form | |
204 | (set (pseudo-reg) (expression)). | |
205 | Function want_to_gcse_p says what these are. | |
206 | ||
207 | PRE handles moving invariant expressions out of loops (by treating them as | |
208 | partially redundant). | |
209 | ||
210 | Eventually it would be nice to replace cse.c/gcse.c with SSA (static single | |
211 | assignment) based GVN (global value numbering). L. T. Simpson's paper | |
212 | (Rice University) on value numbering is a useful reference for this. | |
213 | ||
214 | ********************** | |
215 | ||
216 | We used to support multiple passes but there are diminishing returns in | |
217 | doing so. The first pass usually makes 90% of the changes that are doable. | |
218 | A second pass can make a few more changes made possible by the first pass. | |
219 | Experiments show any further passes don't make enough changes to justify | |
220 | the expense. | |
221 | ||
222 | A study of spec92 using an unlimited number of passes: | |
223 | [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83, | |
224 | [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2, | |
225 | [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1 | |
226 | ||
227 | It was found doing copy propagation between each pass enables further | |
228 | substitutions. | |
229 | ||
230 | PRE is quite expensive in complicated functions because the DFA can take | |
231 | awhile to converge. Hence we only perform one pass. The parameter max-gcse-passes can | |
232 | be modified if one wants to experiment. | |
233 | ||
234 | ********************** | |
235 | ||
236 | The steps for PRE are: | |
237 | ||
238 | 1) Build the hash table of expressions we wish to GCSE (expr_hash_table). | |
239 | ||
240 | 2) Perform the data flow analysis for PRE. | |
241 | ||
242 | 3) Delete the redundant instructions | |
243 | ||
244 | 4) Insert the required copies [if any] that make the partially | |
245 | redundant instructions fully redundant. | |
246 | ||
247 | 5) For other reaching expressions, insert an instruction to copy the value | |
248 | to a newly created pseudo that will reach the redundant instruction. | |
249 | ||
250 | The deletion is done first so that when we do insertions we | |
251 | know which pseudo reg to use. | |
252 | ||
253 | Various papers have argued that PRE DFA is expensive (O(n^2)) and others | |
254 | argue it is not. The number of iterations for the algorithm to converge | |
255 | is typically 2-4 so I don't view it as that expensive (relatively speaking). | |
256 | ||
257 | PRE GCSE depends heavily on the second CSE pass to clean up the copies | |
258 | we create. To make an expression reach the place where it's redundant, | |
259 | the result of the expression is copied to a new register, and the redundant | |
260 | expression is deleted by replacing it with this new register. Classic GCSE | |
261 | doesn't have this problem as much as it computes the reaching defs of | |
262 | each register in each block and thus can try to use an existing register. | |
263 | ||
264 | ********************** | |
265 | ||
266 | A fair bit of simplicity is created by creating small functions for simple | |
267 | tasks, even when the function is only called in one place. This may | |
268 | measurably slow things down [or may not] by creating more function call | |
269 | overhead than is necessary. The source is laid out so that it's trivial | |
270 | to make the affected functions inline so that one can measure what speed | |
271 | up, if any, can be achieved, and maybe later when things settle things can | |
272 | be rearranged. | |
273 | ||
274 | Help stamp out big monolithic functions! */ | |
275 | \f | |
276 | /* GCSE global vars. */ | |
277 | ||
278 | /* -dG dump file. */ | |
279 | static FILE *gcse_file; | |
280 | ||
281 | /* Note whether or not we should run jump optimization after gcse. We | |
282 | want to do this for two cases. | |
283 | ||
284 | * If we changed any jumps via cprop. | |
285 | ||
286 | * If we added any labels via edge splitting. */ | |
287 | ||
288 | static int run_jump_opt_after_gcse; | |
289 | ||
290 | /* Bitmaps are normally not included in debugging dumps. | |
291 | However it's useful to be able to print them from GDB. | |
292 | We could create special functions for this, but it's simpler to | |
293 | just allow passing stderr to the dump_foo fns. Since stderr can | |
294 | be a macro, we store a copy here. */ | |
295 | static FILE *debug_stderr; | |
296 | ||
297 | /* An obstack for our working variables. */ | |
298 | static struct obstack gcse_obstack; | |
299 | ||
300 | /* Non-zero for each mode that supports (set (reg) (reg)). | |
301 | This is trivially true for integer and floating point values. | |
302 | It may or may not be true for condition codes. */ | |
303 | static char can_copy_p[(int) NUM_MACHINE_MODES]; | |
304 | ||
305 | /* Non-zero if can_copy_p has been initialized. */ | |
306 | static int can_copy_init_p; | |
307 | ||
308 | struct reg_use {rtx reg_rtx; }; | |
309 | ||
310 | /* Hash table of expressions. */ | |
311 | ||
312 | struct expr | |
313 | { | |
314 | /* The expression (SET_SRC for expressions, PATTERN for assignments). */ | |
315 | rtx expr; | |
316 | /* Index in the available expression bitmaps. */ | |
317 | int bitmap_index; | |
318 | /* Next entry with the same hash. */ | |
319 | struct expr *next_same_hash; | |
320 | /* List of anticipatable occurrences in basic blocks in the function. | |
321 | An "anticipatable occurrence" is one that is the first occurrence in the | |
322 | basic block, the operands are not modified in the basic block prior | |
323 | to the occurrence and the output is not used between the start of | |
324 | the block and the occurrence. */ | |
325 | struct occr *antic_occr; | |
326 | /* List of available occurrence in basic blocks in the function. | |
327 | An "available occurrence" is one that is the last occurrence in the | |
328 | basic block and the operands are not modified by following statements in | |
329 | the basic block [including this insn]. */ | |
330 | struct occr *avail_occr; | |
331 | /* Non-null if the computation is PRE redundant. | |
332 | The value is the newly created pseudo-reg to record a copy of the | |
333 | expression in all the places that reach the redundant copy. */ | |
334 | rtx reaching_reg; | |
335 | }; | |
336 | ||
337 | /* Occurrence of an expression. | |
338 | There is one per basic block. If a pattern appears more than once the | |
339 | last appearance is used [or first for anticipatable expressions]. */ | |
340 | ||
341 | struct occr | |
342 | { | |
343 | /* Next occurrence of this expression. */ | |
344 | struct occr *next; | |
345 | /* The insn that computes the expression. */ | |
346 | rtx insn; | |
347 | /* Non-zero if this [anticipatable] occurrence has been deleted. */ | |
348 | char deleted_p; | |
349 | /* Non-zero if this [available] occurrence has been copied to | |
350 | reaching_reg. */ | |
351 | /* ??? This is mutually exclusive with deleted_p, so they could share | |
352 | the same byte. */ | |
353 | char copied_p; | |
354 | }; | |
355 | ||
356 | /* Expression and copy propagation hash tables. | |
357 | Each hash table is an array of buckets. | |
358 | ??? It is known that if it were an array of entries, structure elements | |
359 | `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is | |
360 | not clear whether in the final analysis a sufficient amount of memory would | |
361 | be saved as the size of the available expression bitmaps would be larger | |
362 | [one could build a mapping table without holes afterwards though]. | |
363 | Someday I'll perform the computation and figure it out. */ | |
364 | ||
365 | /* Total size of the expression hash table, in elements. */ | |
366 | static unsigned int expr_hash_table_size; | |
367 | ||
368 | /* The table itself. | |
369 | This is an array of `expr_hash_table_size' elements. */ | |
370 | static struct expr **expr_hash_table; | |
371 | ||
372 | /* Total size of the copy propagation hash table, in elements. */ | |
373 | static unsigned int set_hash_table_size; | |
374 | ||
375 | /* The table itself. | |
376 | This is an array of `set_hash_table_size' elements. */ | |
377 | static struct expr **set_hash_table; | |
378 | ||
379 | /* Mapping of uids to cuids. | |
380 | Only real insns get cuids. */ | |
381 | static int *uid_cuid; | |
382 | ||
383 | /* Highest UID in UID_CUID. */ | |
384 | static int max_uid; | |
385 | ||
386 | /* Get the cuid of an insn. */ | |
387 | #ifdef ENABLE_CHECKING | |
388 | #define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)]) | |
389 | #else | |
390 | #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)]) | |
391 | #endif | |
392 | ||
393 | /* Number of cuids. */ | |
394 | static int max_cuid; | |
395 | ||
396 | /* Mapping of cuids to insns. */ | |
397 | static rtx *cuid_insn; | |
398 | ||
399 | /* Get insn from cuid. */ | |
400 | #define CUID_INSN(CUID) (cuid_insn[CUID]) | |
401 | ||
402 | /* Maximum register number in function prior to doing gcse + 1. | |
403 | Registers created during this pass have regno >= max_gcse_regno. | |
404 | This is named with "gcse" to not collide with global of same name. */ | |
405 | static unsigned int max_gcse_regno; | |
406 | ||
407 | /* Maximum number of cse-able expressions found. */ | |
408 | static int n_exprs; | |
409 | ||
410 | /* Maximum number of assignments for copy propagation found. */ | |
411 | static int n_sets; | |
412 | ||
413 | /* Table of registers that are modified. | |
414 | ||
415 | For each register, each element is a list of places where the pseudo-reg | |
416 | is set. | |
417 | ||
418 | For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only | |
419 | requires knowledge of which blocks kill which regs [and thus could use | |
420 | a bitmap instead of the lists `reg_set_table' uses]. | |
421 | ||
422 | `reg_set_table' and could be turned into an array of bitmaps (num-bbs x | |
423 | num-regs) [however perhaps it may be useful to keep the data as is]. One | |
424 | advantage of recording things this way is that `reg_set_table' is fairly | |
425 | sparse with respect to pseudo regs but for hard regs could be fairly dense | |
426 | [relatively speaking]. And recording sets of pseudo-regs in lists speeds | |
427 | up functions like compute_transp since in the case of pseudo-regs we only | |
428 | need to iterate over the number of times a pseudo-reg is set, not over the | |
429 | number of basic blocks [clearly there is a bit of a slow down in the cases | |
430 | where a pseudo is set more than once in a block, however it is believed | |
431 | that the net effect is to speed things up]. This isn't done for hard-regs | |
432 | because recording call-clobbered hard-regs in `reg_set_table' at each | |
433 | function call can consume a fair bit of memory, and iterating over | |
434 | hard-regs stored this way in compute_transp will be more expensive. */ | |
435 | ||
436 | typedef struct reg_set | |
437 | { | |
438 | /* The next setting of this register. */ | |
439 | struct reg_set *next; | |
440 | /* The insn where it was set. */ | |
441 | rtx insn; | |
442 | } reg_set; | |
443 | ||
444 | static reg_set **reg_set_table; | |
445 | ||
446 | /* Size of `reg_set_table'. | |
447 | The table starts out at max_gcse_regno + slop, and is enlarged as | |
448 | necessary. */ | |
449 | static int reg_set_table_size; | |
450 | ||
451 | /* Amount to grow `reg_set_table' by when it's full. */ | |
452 | #define REG_SET_TABLE_SLOP 100 | |
453 | ||
454 | /* This is a list of expressions which are MEMs and will be used by load | |
455 | or store motion. | |
456 | Load motion tracks MEMs which aren't killed by | |
457 | anything except itself. (ie, loads and stores to a single location). | |
458 | We can then allow movement of these MEM refs with a little special | |
459 | allowance. (all stores copy the same value to the reaching reg used | |
460 | for the loads). This means all values used to store into memory must have | |
461 | no side effects so we can re-issue the setter value. | |
462 | Store Motion uses this structure as an expression table to track stores | |
463 | which look interesting, and might be moveable towards the exit block. */ | |
464 | ||
465 | struct ls_expr | |
466 | { | |
467 | struct expr * expr; /* Gcse expression reference for LM. */ | |
468 | rtx pattern; /* Pattern of this mem. */ | |
469 | rtx loads; /* INSN list of loads seen. */ | |
470 | rtx stores; /* INSN list of stores seen. */ | |
471 | struct ls_expr * next; /* Next in the list. */ | |
472 | int invalid; /* Invalid for some reason. */ | |
473 | int index; /* If it maps to a bitmap index. */ | |
474 | int hash_index; /* Index when in a hash table. */ | |
475 | rtx reaching_reg; /* Register to use when re-writing. */ | |
476 | }; | |
477 | ||
478 | /* Head of the list of load/store memory refs. */ | |
479 | static struct ls_expr * pre_ldst_mems = NULL; | |
480 | ||
481 | /* Bitmap containing one bit for each register in the program. | |
482 | Used when performing GCSE to track which registers have been set since | |
483 | the start of the basic block. */ | |
484 | static regset reg_set_bitmap; | |
485 | ||
486 | /* For each block, a bitmap of registers set in the block. | |
487 | This is used by expr_killed_p and compute_transp. | |
488 | It is computed during hash table computation and not by compute_sets | |
489 | as it includes registers added since the last pass (or between cprop and | |
490 | gcse) and it's currently not easy to realloc sbitmap vectors. */ | |
491 | static sbitmap *reg_set_in_block; | |
492 | ||
493 | /* Array, indexed by basic block number for a list of insns which modify | |
494 | memory within that block. */ | |
495 | static rtx * modify_mem_list; | |
496 | bitmap modify_mem_list_set; | |
497 | ||
498 | /* This array parallels modify_mem_list, but is kept canonicalized. */ | |
499 | static rtx * canon_modify_mem_list; | |
500 | bitmap canon_modify_mem_list_set; | |
501 | /* Various variables for statistics gathering. */ | |
502 | ||
503 | /* Memory used in a pass. | |
504 | This isn't intended to be absolutely precise. Its intent is only | |
505 | to keep an eye on memory usage. */ | |
506 | static int bytes_used; | |
507 | ||
508 | /* GCSE substitutions made. */ | |
509 | static int gcse_subst_count; | |
510 | /* Number of copy instructions created. */ | |
511 | static int gcse_create_count; | |
512 | /* Number of constants propagated. */ | |
513 | static int const_prop_count; | |
514 | /* Number of copys propagated. */ | |
515 | static int copy_prop_count; | |
516 | \f | |
517 | /* These variables are used by classic GCSE. | |
518 | Normally they'd be defined a bit later, but `rd_gen' needs to | |
519 | be declared sooner. */ | |
520 | ||
521 | /* Each block has a bitmap of each type. | |
522 | The length of each blocks bitmap is: | |
523 | ||
524 | max_cuid - for reaching definitions | |
525 | n_exprs - for available expressions | |
526 | ||
527 | Thus we view the bitmaps as 2 dimensional arrays. i.e. | |
528 | rd_kill[block_num][cuid_num] | |
529 | ae_kill[block_num][expr_num] */ | |
530 | ||
531 | /* For reaching defs */ | |
532 | static sbitmap *rd_kill, *rd_gen, *reaching_defs, *rd_out; | |
533 | ||
534 | /* for available exprs */ | |
535 | static sbitmap *ae_kill, *ae_gen, *ae_in, *ae_out; | |
536 | ||
537 | /* Objects of this type are passed around by the null-pointer check | |
538 | removal routines. */ | |
539 | struct null_pointer_info | |
540 | { | |
541 | /* The basic block being processed. */ | |
542 | basic_block current_block; | |
543 | /* The first register to be handled in this pass. */ | |
544 | unsigned int min_reg; | |
545 | /* One greater than the last register to be handled in this pass. */ | |
546 | unsigned int max_reg; | |
547 | sbitmap *nonnull_local; | |
548 | sbitmap *nonnull_killed; | |
549 | }; | |
550 | \f | |
551 | static void compute_can_copy PARAMS ((void)); | |
552 | static char *gmalloc PARAMS ((unsigned int)); | |
553 | static char *grealloc PARAMS ((char *, unsigned int)); | |
554 | static char *gcse_alloc PARAMS ((unsigned long)); | |
555 | static void alloc_gcse_mem PARAMS ((rtx)); | |
556 | static void free_gcse_mem PARAMS ((void)); | |
557 | static void alloc_reg_set_mem PARAMS ((int)); | |
558 | static void free_reg_set_mem PARAMS ((void)); | |
559 | static int get_bitmap_width PARAMS ((int, int, int)); | |
560 | static void record_one_set PARAMS ((int, rtx)); | |
561 | static void record_set_info PARAMS ((rtx, rtx, void *)); | |
562 | static void compute_sets PARAMS ((rtx)); | |
563 | static void hash_scan_insn PARAMS ((rtx, int, int)); | |
564 | static void hash_scan_set PARAMS ((rtx, rtx, int)); | |
565 | static void hash_scan_clobber PARAMS ((rtx, rtx)); | |
566 | static void hash_scan_call PARAMS ((rtx, rtx)); | |
567 | static int want_to_gcse_p PARAMS ((rtx)); | |
568 | static int oprs_unchanged_p PARAMS ((rtx, rtx, int)); | |
569 | static int oprs_anticipatable_p PARAMS ((rtx, rtx)); | |
570 | static int oprs_available_p PARAMS ((rtx, rtx)); | |
571 | static void insert_expr_in_table PARAMS ((rtx, enum machine_mode, rtx, | |
572 | int, int)); | |
573 | static void insert_set_in_table PARAMS ((rtx, rtx)); | |
574 | static unsigned int hash_expr PARAMS ((rtx, enum machine_mode, int *, int)); | |
575 | static unsigned int hash_expr_1 PARAMS ((rtx, enum machine_mode, int *)); | |
576 | static unsigned int hash_string_1 PARAMS ((const char *)); | |
577 | static unsigned int hash_set PARAMS ((int, int)); | |
578 | static int expr_equiv_p PARAMS ((rtx, rtx)); | |
579 | static void record_last_reg_set_info PARAMS ((rtx, int)); | |
580 | static void record_last_mem_set_info PARAMS ((rtx)); | |
581 | static void record_last_set_info PARAMS ((rtx, rtx, void *)); | |
582 | static void compute_hash_table PARAMS ((int)); | |
583 | static void alloc_set_hash_table PARAMS ((int)); | |
584 | static void free_set_hash_table PARAMS ((void)); | |
585 | static void compute_set_hash_table PARAMS ((void)); | |
586 | static void alloc_expr_hash_table PARAMS ((unsigned int)); | |
587 | static void free_expr_hash_table PARAMS ((void)); | |
588 | static void compute_expr_hash_table PARAMS ((void)); | |
589 | static void dump_hash_table PARAMS ((FILE *, const char *, struct expr **, | |
590 | int, int)); | |
591 | static struct expr *lookup_expr PARAMS ((rtx)); | |
592 | static struct expr *lookup_set PARAMS ((unsigned int, rtx)); | |
593 | static struct expr *next_set PARAMS ((unsigned int, struct expr *)); | |
594 | static void reset_opr_set_tables PARAMS ((void)); | |
595 | static int oprs_not_set_p PARAMS ((rtx, rtx)); | |
596 | static void mark_call PARAMS ((rtx)); | |
597 | static void mark_set PARAMS ((rtx, rtx)); | |
598 | static void mark_clobber PARAMS ((rtx, rtx)); | |
599 | static void mark_oprs_set PARAMS ((rtx)); | |
600 | static void alloc_cprop_mem PARAMS ((int, int)); | |
601 | static void free_cprop_mem PARAMS ((void)); | |
602 | static void compute_transp PARAMS ((rtx, int, sbitmap *, int)); | |
603 | static void compute_transpout PARAMS ((void)); | |
604 | static void compute_local_properties PARAMS ((sbitmap *, sbitmap *, sbitmap *, | |
605 | int)); | |
606 | static void compute_cprop_data PARAMS ((void)); | |
607 | static void find_used_regs PARAMS ((rtx *, void *)); | |
608 | static int try_replace_reg PARAMS ((rtx, rtx, rtx)); | |
609 | static struct expr *find_avail_set PARAMS ((int, rtx)); | |
610 | static int cprop_jump PARAMS ((basic_block, rtx, rtx, rtx, rtx)); | |
611 | static void mems_conflict_for_gcse_p PARAMS ((rtx, rtx, void *)); | |
612 | static int load_killed_in_block_p PARAMS ((basic_block, int, rtx, int)); | |
613 | static void canon_list_insert PARAMS ((rtx, rtx, void *)); | |
614 | static int cprop_insn PARAMS ((rtx, int)); | |
615 | static int cprop PARAMS ((int)); | |
616 | static int one_cprop_pass PARAMS ((int, int)); | |
617 | static bool constprop_register PARAMS ((rtx, rtx, rtx, int)); | |
618 | static struct expr *find_bypass_set PARAMS ((int, int)); | |
619 | static int bypass_block PARAMS ((basic_block, rtx, rtx)); | |
620 | static int bypass_conditional_jumps PARAMS ((void)); | |
621 | static void alloc_pre_mem PARAMS ((int, int)); | |
622 | static void free_pre_mem PARAMS ((void)); | |
623 | static void compute_pre_data PARAMS ((void)); | |
624 | static int pre_expr_reaches_here_p PARAMS ((basic_block, struct expr *, | |
625 | basic_block)); | |
626 | static void insert_insn_end_bb PARAMS ((struct expr *, basic_block, int)); | |
627 | static void pre_insert_copy_insn PARAMS ((struct expr *, rtx)); | |
628 | static void pre_insert_copies PARAMS ((void)); | |
629 | static int pre_delete PARAMS ((void)); | |
630 | static int pre_gcse PARAMS ((void)); | |
631 | static int one_pre_gcse_pass PARAMS ((int)); | |
632 | static void add_label_notes PARAMS ((rtx, rtx)); | |
633 | static void alloc_code_hoist_mem PARAMS ((int, int)); | |
634 | static void free_code_hoist_mem PARAMS ((void)); | |
635 | static void compute_code_hoist_vbeinout PARAMS ((void)); | |
636 | static void compute_code_hoist_data PARAMS ((void)); | |
637 | static int hoist_expr_reaches_here_p PARAMS ((basic_block, int, basic_block, | |
638 | char *)); | |
639 | static void hoist_code PARAMS ((void)); | |
640 | static int one_code_hoisting_pass PARAMS ((void)); | |
641 | static void alloc_rd_mem PARAMS ((int, int)); | |
642 | static void free_rd_mem PARAMS ((void)); | |
643 | static void handle_rd_kill_set PARAMS ((rtx, int, basic_block)); | |
644 | static void compute_kill_rd PARAMS ((void)); | |
645 | static void compute_rd PARAMS ((void)); | |
646 | static void alloc_avail_expr_mem PARAMS ((int, int)); | |
647 | static void free_avail_expr_mem PARAMS ((void)); | |
648 | static void compute_ae_gen PARAMS ((void)); | |
649 | static int expr_killed_p PARAMS ((rtx, basic_block)); | |
650 | static void compute_ae_kill PARAMS ((sbitmap *, sbitmap *)); | |
651 | static int expr_reaches_here_p PARAMS ((struct occr *, struct expr *, | |
652 | basic_block, int)); | |
653 | static rtx computing_insn PARAMS ((struct expr *, rtx)); | |
654 | static int def_reaches_here_p PARAMS ((rtx, rtx)); | |
655 | static int can_disregard_other_sets PARAMS ((struct reg_set **, rtx, int)); | |
656 | static int handle_avail_expr PARAMS ((rtx, struct expr *)); | |
657 | static int classic_gcse PARAMS ((void)); | |
658 | static int one_classic_gcse_pass PARAMS ((int)); | |
659 | static void invalidate_nonnull_info PARAMS ((rtx, rtx, void *)); | |
660 | static int delete_null_pointer_checks_1 PARAMS ((unsigned int *, | |
661 | sbitmap *, sbitmap *, | |
662 | struct null_pointer_info *)); | |
663 | static rtx process_insert_insn PARAMS ((struct expr *)); | |
664 | static int pre_edge_insert PARAMS ((struct edge_list *, struct expr **)); | |
665 | static int expr_reaches_here_p_work PARAMS ((struct occr *, struct expr *, | |
666 | basic_block, int, char *)); | |
667 | static int pre_expr_reaches_here_p_work PARAMS ((basic_block, struct expr *, | |
668 | basic_block, char *)); | |
669 | static struct ls_expr * ldst_entry PARAMS ((rtx)); | |
670 | static void free_ldst_entry PARAMS ((struct ls_expr *)); | |
671 | static void free_ldst_mems PARAMS ((void)); | |
672 | static void print_ldst_list PARAMS ((FILE *)); | |
673 | static struct ls_expr * find_rtx_in_ldst PARAMS ((rtx)); | |
674 | static int enumerate_ldsts PARAMS ((void)); | |
675 | static inline struct ls_expr * first_ls_expr PARAMS ((void)); | |
676 | static inline struct ls_expr * next_ls_expr PARAMS ((struct ls_expr *)); | |
677 | static int simple_mem PARAMS ((rtx)); | |
678 | static void invalidate_any_buried_refs PARAMS ((rtx)); | |
679 | static void compute_ld_motion_mems PARAMS ((void)); | |
680 | static void trim_ld_motion_mems PARAMS ((void)); | |
681 | static void update_ld_motion_stores PARAMS ((struct expr *)); | |
682 | static void reg_set_info PARAMS ((rtx, rtx, void *)); | |
683 | static int store_ops_ok PARAMS ((rtx, basic_block)); | |
684 | static void find_moveable_store PARAMS ((rtx)); | |
685 | static int compute_store_table PARAMS ((void)); | |
686 | static int load_kills_store PARAMS ((rtx, rtx)); | |
687 | static int find_loads PARAMS ((rtx, rtx)); | |
688 | static int store_killed_in_insn PARAMS ((rtx, rtx)); | |
689 | static int store_killed_after PARAMS ((rtx, rtx, basic_block)); | |
690 | static int store_killed_before PARAMS ((rtx, rtx, basic_block)); | |
691 | static void build_store_vectors PARAMS ((void)); | |
692 | static void insert_insn_start_bb PARAMS ((rtx, basic_block)); | |
693 | static int insert_store PARAMS ((struct ls_expr *, edge)); | |
694 | static void replace_store_insn PARAMS ((rtx, rtx, basic_block)); | |
695 | static void delete_store PARAMS ((struct ls_expr *, | |
696 | basic_block)); | |
697 | static void free_store_memory PARAMS ((void)); | |
698 | static void store_motion PARAMS ((void)); | |
699 | static void free_insn_expr_list_list PARAMS ((rtx *)); | |
700 | static void clear_modify_mem_tables PARAMS ((void)); | |
701 | static void free_modify_mem_tables PARAMS ((void)); | |
702 | static rtx gcse_emit_move_after PARAMS ((rtx, rtx, rtx)); | |
703 | static bool do_local_cprop PARAMS ((rtx, rtx, int)); | |
704 | static void local_cprop_pass PARAMS ((int)); | |
705 | \f | |
706 | /* Entry point for global common subexpression elimination. | |
707 | F is the first instruction in the function. */ | |
708 | ||
709 | int | |
710 | gcse_main (f, file) | |
711 | rtx f; | |
712 | FILE *file; | |
713 | { | |
714 | int changed, pass; | |
715 | /* Bytes used at start of pass. */ | |
716 | int initial_bytes_used; | |
717 | /* Maximum number of bytes used by a pass. */ | |
718 | int max_pass_bytes; | |
719 | /* Point to release obstack data from for each pass. */ | |
720 | char *gcse_obstack_bottom; | |
721 | ||
722 | /* Insertion of instructions on edges can create new basic blocks; we | |
723 | need the original basic block count so that we can properly deallocate | |
724 | arrays sized on the number of basic blocks originally in the cfg. */ | |
725 | int orig_bb_count; | |
726 | /* We do not construct an accurate cfg in functions which call | |
727 | setjmp, so just punt to be safe. */ | |
728 | if (current_function_calls_setjmp) | |
729 | return 0; | |
730 | ||
731 | /* Assume that we do not need to run jump optimizations after gcse. */ | |
732 | run_jump_opt_after_gcse = 0; | |
733 | ||
734 | /* For calling dump_foo fns from gdb. */ | |
735 | debug_stderr = stderr; | |
736 | gcse_file = file; | |
737 | ||
738 | /* Identify the basic block information for this function, including | |
739 | successors and predecessors. */ | |
740 | max_gcse_regno = max_reg_num (); | |
741 | ||
742 | if (file) | |
743 | dump_flow_info (file); | |
744 | ||
745 | orig_bb_count = n_basic_blocks; | |
746 | /* Return if there's nothing to do. */ | |
747 | if (n_basic_blocks <= 1) | |
748 | return 0; | |
749 | ||
750 | /* Trying to perform global optimizations on flow graphs which have | |
751 | a high connectivity will take a long time and is unlikely to be | |
752 | particularly useful. | |
753 | ||
754 | In normal circumstances a cfg should have about twice as many edges | |
755 | as blocks. But we do not want to punish small functions which have | |
756 | a couple switch statements. So we require a relatively large number | |
757 | of basic blocks and the ratio of edges to blocks to be high. */ | |
758 | if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20) | |
759 | { | |
760 | if (warn_disabled_optimization) | |
761 | warning ("GCSE disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block", | |
762 | n_basic_blocks, n_edges / n_basic_blocks); | |
763 | return 0; | |
764 | } | |
765 | ||
766 | /* If allocating memory for the cprop bitmap would take up too much | |
767 | storage it's better just to disable the optimization. */ | |
768 | if ((n_basic_blocks | |
769 | * SBITMAP_SET_SIZE (max_gcse_regno) | |
770 | * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY) | |
771 | { | |
772 | if (warn_disabled_optimization) | |
773 | warning ("GCSE disabled: %d basic blocks and %d registers", | |
774 | n_basic_blocks, max_gcse_regno); | |
775 | ||
776 | return 0; | |
777 | } | |
778 | ||
779 | /* See what modes support reg/reg copy operations. */ | |
780 | if (! can_copy_init_p) | |
781 | { | |
782 | compute_can_copy (); | |
783 | can_copy_init_p = 1; | |
784 | } | |
785 | ||
786 | gcc_obstack_init (&gcse_obstack); | |
787 | bytes_used = 0; | |
788 | ||
789 | /* We need alias. */ | |
790 | init_alias_analysis (); | |
791 | /* Record where pseudo-registers are set. This data is kept accurate | |
792 | during each pass. ??? We could also record hard-reg information here | |
793 | [since it's unchanging], however it is currently done during hash table | |
794 | computation. | |
795 | ||
796 | It may be tempting to compute MEM set information here too, but MEM sets | |
797 | will be subject to code motion one day and thus we need to compute | |
798 | information about memory sets when we build the hash tables. */ | |
799 | ||
800 | alloc_reg_set_mem (max_gcse_regno); | |
801 | compute_sets (f); | |
802 | ||
803 | pass = 0; | |
804 | initial_bytes_used = bytes_used; | |
805 | max_pass_bytes = 0; | |
806 | gcse_obstack_bottom = gcse_alloc (1); | |
807 | changed = 1; | |
808 | while (changed && pass < MAX_GCSE_PASSES) | |
809 | { | |
810 | changed = 0; | |
811 | if (file) | |
812 | fprintf (file, "GCSE pass %d\n\n", pass + 1); | |
813 | ||
814 | /* Initialize bytes_used to the space for the pred/succ lists, | |
815 | and the reg_set_table data. */ | |
816 | bytes_used = initial_bytes_used; | |
817 | ||
818 | /* Each pass may create new registers, so recalculate each time. */ | |
819 | max_gcse_regno = max_reg_num (); | |
820 | ||
821 | alloc_gcse_mem (f); | |
822 | ||
823 | /* Don't allow constant propagation to modify jumps | |
824 | during this pass. */ | |
825 | changed = one_cprop_pass (pass + 1, 0); | |
826 | ||
827 | if (optimize_size) | |
828 | changed |= one_classic_gcse_pass (pass + 1); | |
829 | else | |
830 | { | |
831 | changed |= one_pre_gcse_pass (pass + 1); | |
832 | /* We may have just created new basic blocks. Release and | |
833 | recompute various things which are sized on the number of | |
834 | basic blocks. */ | |
835 | if (changed) | |
836 | { | |
837 | free_modify_mem_tables (); | |
838 | modify_mem_list | |
839 | = (rtx *) gmalloc (last_basic_block * sizeof (rtx)); | |
840 | canon_modify_mem_list | |
841 | = (rtx *) gmalloc (last_basic_block * sizeof (rtx)); | |
842 | memset ((char *) modify_mem_list, 0, last_basic_block * sizeof (rtx)); | |
843 | memset ((char *) canon_modify_mem_list, 0, last_basic_block * sizeof (rtx)); | |
844 | orig_bb_count = n_basic_blocks; | |
845 | } | |
846 | free_reg_set_mem (); | |
847 | alloc_reg_set_mem (max_reg_num ()); | |
848 | compute_sets (f); | |
849 | run_jump_opt_after_gcse = 1; | |
850 | } | |
851 | ||
852 | if (max_pass_bytes < bytes_used) | |
853 | max_pass_bytes = bytes_used; | |
854 | ||
855 | /* Free up memory, then reallocate for code hoisting. We can | |
856 | not re-use the existing allocated memory because the tables | |
857 | will not have info for the insns or registers created by | |
858 | partial redundancy elimination. */ | |
859 | free_gcse_mem (); | |
860 | ||
861 | /* It does not make sense to run code hoisting unless we optimizing | |
862 | for code size -- it rarely makes programs faster, and can make | |
863 | them bigger if we did partial redundancy elimination (when optimizing | |
864 | for space, we use a classic gcse algorithm instead of partial | |
865 | redundancy algorithms). */ | |
866 | if (optimize_size) | |
867 | { | |
868 | max_gcse_regno = max_reg_num (); | |
869 | alloc_gcse_mem (f); | |
870 | changed |= one_code_hoisting_pass (); | |
871 | free_gcse_mem (); | |
872 | ||
873 | if (max_pass_bytes < bytes_used) | |
874 | max_pass_bytes = bytes_used; | |
875 | } | |
876 | ||
877 | if (file) | |
878 | { | |
879 | fprintf (file, "\n"); | |
880 | fflush (file); | |
881 | } | |
882 | ||
883 | obstack_free (&gcse_obstack, gcse_obstack_bottom); | |
884 | pass++; | |
885 | } | |
886 | ||
887 | /* Do one last pass of copy propagation, including cprop into | |
888 | conditional jumps. */ | |
889 | ||
890 | max_gcse_regno = max_reg_num (); | |
891 | alloc_gcse_mem (f); | |
892 | /* This time, go ahead and allow cprop to alter jumps. */ | |
893 | one_cprop_pass (pass + 1, 1); | |
894 | free_gcse_mem (); | |
895 | ||
896 | if (file) | |
897 | { | |
898 | fprintf (file, "GCSE of %s: %d basic blocks, ", | |
899 | current_function_name, n_basic_blocks); | |
900 | fprintf (file, "%d pass%s, %d bytes\n\n", | |
901 | pass, pass > 1 ? "es" : "", max_pass_bytes); | |
902 | } | |
903 | ||
904 | obstack_free (&gcse_obstack, NULL); | |
905 | free_reg_set_mem (); | |
906 | /* We are finished with alias. */ | |
907 | end_alias_analysis (); | |
908 | allocate_reg_info (max_reg_num (), FALSE, FALSE); | |
909 | ||
910 | /* Store motion disabled until it is fixed. */ | |
911 | if (0 && !optimize_size && flag_gcse_sm) | |
912 | store_motion (); | |
913 | /* Record where pseudo-registers are set. */ | |
914 | return run_jump_opt_after_gcse; | |
915 | } | |
916 | \f | |
917 | /* Misc. utilities. */ | |
918 | ||
919 | /* Compute which modes support reg/reg copy operations. */ | |
920 | ||
921 | static void | |
922 | compute_can_copy () | |
923 | { | |
924 | int i; | |
925 | #ifndef AVOID_CCMODE_COPIES | |
926 | rtx reg, insn; | |
927 | #endif | |
928 | memset (can_copy_p, 0, NUM_MACHINE_MODES); | |
929 | ||
930 | start_sequence (); | |
931 | for (i = 0; i < NUM_MACHINE_MODES; i++) | |
932 | if (GET_MODE_CLASS (i) == MODE_CC) | |
933 | { | |
934 | #ifdef AVOID_CCMODE_COPIES | |
935 | can_copy_p[i] = 0; | |
936 | #else | |
937 | reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1); | |
938 | insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg)); | |
939 | if (recog (PATTERN (insn), insn, NULL) >= 0) | |
940 | can_copy_p[i] = 1; | |
941 | #endif | |
942 | } | |
943 | else | |
944 | can_copy_p[i] = 1; | |
945 | ||
946 | end_sequence (); | |
947 | } | |
948 | \f | |
949 | /* Cover function to xmalloc to record bytes allocated. */ | |
950 | ||
951 | static char * | |
952 | gmalloc (size) | |
953 | unsigned int size; | |
954 | { | |
955 | bytes_used += size; | |
956 | return xmalloc (size); | |
957 | } | |
958 | ||
959 | /* Cover function to xrealloc. | |
960 | We don't record the additional size since we don't know it. | |
961 | It won't affect memory usage stats much anyway. */ | |
962 | ||
963 | static char * | |
964 | grealloc (ptr, size) | |
965 | char *ptr; | |
966 | unsigned int size; | |
967 | { | |
968 | return xrealloc (ptr, size); | |
969 | } | |
970 | ||
971 | /* Cover function to obstack_alloc. */ | |
972 | ||
973 | static char * | |
974 | gcse_alloc (size) | |
975 | unsigned long size; | |
976 | { | |
977 | bytes_used += size; | |
978 | return (char *) obstack_alloc (&gcse_obstack, size); | |
979 | } | |
980 | ||
981 | /* Allocate memory for the cuid mapping array, | |
982 | and reg/memory set tracking tables. | |
983 | ||
984 | This is called at the start of each pass. */ | |
985 | ||
986 | static void | |
987 | alloc_gcse_mem (f) | |
988 | rtx f; | |
989 | { | |
990 | int i, n; | |
991 | rtx insn; | |
992 | ||
993 | /* Find the largest UID and create a mapping from UIDs to CUIDs. | |
994 | CUIDs are like UIDs except they increase monotonically, have no gaps, | |
995 | and only apply to real insns. */ | |
996 | ||
997 | max_uid = get_max_uid (); | |
998 | n = (max_uid + 1) * sizeof (int); | |
999 | uid_cuid = (int *) gmalloc (n); | |
1000 | memset ((char *) uid_cuid, 0, n); | |
1001 | for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) | |
1002 | { | |
1003 | if (INSN_P (insn)) | |
1004 | uid_cuid[INSN_UID (insn)] = i++; | |
1005 | else | |
1006 | uid_cuid[INSN_UID (insn)] = i; | |
1007 | } | |
1008 | ||
1009 | /* Create a table mapping cuids to insns. */ | |
1010 | ||
1011 | max_cuid = i; | |
1012 | n = (max_cuid + 1) * sizeof (rtx); | |
1013 | cuid_insn = (rtx *) gmalloc (n); | |
1014 | memset ((char *) cuid_insn, 0, n); | |
1015 | for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) | |
1016 | if (INSN_P (insn)) | |
1017 | CUID_INSN (i++) = insn; | |
1018 | ||
1019 | /* Allocate vars to track sets of regs. */ | |
1020 | reg_set_bitmap = BITMAP_XMALLOC (); | |
1021 | ||
1022 | /* Allocate vars to track sets of regs, memory per block. */ | |
1023 | reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (last_basic_block, | |
1024 | max_gcse_regno); | |
1025 | /* Allocate array to keep a list of insns which modify memory in each | |
1026 | basic block. */ | |
1027 | modify_mem_list = (rtx *) gmalloc (last_basic_block * sizeof (rtx)); | |
1028 | canon_modify_mem_list = (rtx *) gmalloc (last_basic_block * sizeof (rtx)); | |
1029 | memset ((char *) modify_mem_list, 0, last_basic_block * sizeof (rtx)); | |
1030 | memset ((char *) canon_modify_mem_list, 0, last_basic_block * sizeof (rtx)); | |
1031 | modify_mem_list_set = BITMAP_XMALLOC (); | |
1032 | canon_modify_mem_list_set = BITMAP_XMALLOC (); | |
1033 | } | |
1034 | ||
1035 | /* Free memory allocated by alloc_gcse_mem. */ | |
1036 | ||
1037 | static void | |
1038 | free_gcse_mem () | |
1039 | { | |
1040 | free (uid_cuid); | |
1041 | free (cuid_insn); | |
1042 | ||
1043 | BITMAP_XFREE (reg_set_bitmap); | |
1044 | ||
1045 | sbitmap_vector_free (reg_set_in_block); | |
1046 | free_modify_mem_tables (); | |
1047 | BITMAP_XFREE (modify_mem_list_set); | |
1048 | BITMAP_XFREE (canon_modify_mem_list_set); | |
1049 | } | |
1050 | ||
1051 | /* Many of the global optimization algorithms work by solving dataflow | |
1052 | equations for various expressions. Initially, some local value is | |
1053 | computed for each expression in each block. Then, the values across the | |
1054 | various blocks are combined (by following flow graph edges) to arrive at | |
1055 | global values. Conceptually, each set of equations is independent. We | |
1056 | may therefore solve all the equations in parallel, solve them one at a | |
1057 | time, or pick any intermediate approach. | |
1058 | ||
1059 | When you're going to need N two-dimensional bitmaps, each X (say, the | |
1060 | number of blocks) by Y (say, the number of expressions), call this | |
1061 | function. It's not important what X and Y represent; only that Y | |
1062 | correspond to the things that can be done in parallel. This function will | |
1063 | return an appropriate chunking factor C; you should solve C sets of | |
1064 | equations in parallel. By going through this function, we can easily | |
1065 | trade space against time; by solving fewer equations in parallel we use | |
1066 | less space. */ | |
1067 | ||
1068 | static int | |
1069 | get_bitmap_width (n, x, y) | |
1070 | int n; | |
1071 | int x; | |
1072 | int y; | |
1073 | { | |
1074 | /* It's not really worth figuring out *exactly* how much memory will | |
1075 | be used by a particular choice. The important thing is to get | |
1076 | something approximately right. */ | |
1077 | size_t max_bitmap_memory = 10 * 1024 * 1024; | |
1078 | ||
1079 | /* The number of bytes we'd use for a single column of minimum | |
1080 | width. */ | |
1081 | size_t column_size = n * x * sizeof (SBITMAP_ELT_TYPE); | |
1082 | ||
1083 | /* Often, it's reasonable just to solve all the equations in | |
1084 | parallel. */ | |
1085 | if (column_size * SBITMAP_SET_SIZE (y) <= max_bitmap_memory) | |
1086 | return y; | |
1087 | ||
1088 | /* Otherwise, pick the largest width we can, without going over the | |
1089 | limit. */ | |
1090 | return SBITMAP_ELT_BITS * ((max_bitmap_memory + column_size - 1) | |
1091 | / column_size); | |
1092 | } | |
1093 | \f | |
1094 | /* Compute the local properties of each recorded expression. | |
1095 | ||
1096 | Local properties are those that are defined by the block, irrespective of | |
1097 | other blocks. | |
1098 | ||
1099 | An expression is transparent in a block if its operands are not modified | |
1100 | in the block. | |
1101 | ||
1102 | An expression is computed (locally available) in a block if it is computed | |
1103 | at least once and expression would contain the same value if the | |
1104 | computation was moved to the end of the block. | |
1105 | ||
1106 | An expression is locally anticipatable in a block if it is computed at | |
1107 | least once and expression would contain the same value if the computation | |
1108 | was moved to the beginning of the block. | |
1109 | ||
1110 | We call this routine for cprop, pre and code hoisting. They all compute | |
1111 | basically the same information and thus can easily share this code. | |
1112 | ||
1113 | TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local | |
1114 | properties. If NULL, then it is not necessary to compute or record that | |
1115 | particular property. | |
1116 | ||
1117 | SETP controls which hash table to look at. If zero, this routine looks at | |
1118 | the expr hash table; if nonzero this routine looks at the set hash table. | |
1119 | Additionally, TRANSP is computed as ~TRANSP, since this is really cprop's | |
1120 | ABSALTERED. */ | |
1121 | ||
1122 | static void | |
1123 | compute_local_properties (transp, comp, antloc, setp) | |
1124 | sbitmap *transp; | |
1125 | sbitmap *comp; | |
1126 | sbitmap *antloc; | |
1127 | int setp; | |
1128 | { | |
1129 | unsigned int i, hash_table_size; | |
1130 | struct expr **hash_table; | |
1131 | ||
1132 | /* Initialize any bitmaps that were passed in. */ | |
1133 | if (transp) | |
1134 | { | |
1135 | if (setp) | |
1136 | sbitmap_vector_zero (transp, last_basic_block); | |
1137 | else | |
1138 | sbitmap_vector_ones (transp, last_basic_block); | |
1139 | } | |
1140 | ||
1141 | if (comp) | |
1142 | sbitmap_vector_zero (comp, last_basic_block); | |
1143 | if (antloc) | |
1144 | sbitmap_vector_zero (antloc, last_basic_block); | |
1145 | ||
1146 | /* We use the same code for cprop, pre and hoisting. For cprop | |
1147 | we care about the set hash table, for pre and hoisting we | |
1148 | care about the expr hash table. */ | |
1149 | hash_table_size = setp ? set_hash_table_size : expr_hash_table_size; | |
1150 | hash_table = setp ? set_hash_table : expr_hash_table; | |
1151 | ||
1152 | for (i = 0; i < hash_table_size; i++) | |
1153 | { | |
1154 | struct expr *expr; | |
1155 | ||
1156 | for (expr = hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
1157 | { | |
1158 | int indx = expr->bitmap_index; | |
1159 | struct occr *occr; | |
1160 | ||
1161 | /* The expression is transparent in this block if it is not killed. | |
1162 | We start by assuming all are transparent [none are killed], and | |
1163 | then reset the bits for those that are. */ | |
1164 | if (transp) | |
1165 | compute_transp (expr->expr, indx, transp, setp); | |
1166 | ||
1167 | /* The occurrences recorded in antic_occr are exactly those that | |
1168 | we want to set to non-zero in ANTLOC. */ | |
1169 | if (antloc) | |
1170 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
1171 | { | |
1172 | SET_BIT (antloc[BLOCK_NUM (occr->insn)], indx); | |
1173 | ||
1174 | /* While we're scanning the table, this is a good place to | |
1175 | initialize this. */ | |
1176 | occr->deleted_p = 0; | |
1177 | } | |
1178 | ||
1179 | /* The occurrences recorded in avail_occr are exactly those that | |
1180 | we want to set to non-zero in COMP. */ | |
1181 | if (comp) | |
1182 | for (occr = expr->avail_occr; occr != NULL; occr = occr->next) | |
1183 | { | |
1184 | SET_BIT (comp[BLOCK_NUM (occr->insn)], indx); | |
1185 | ||
1186 | /* While we're scanning the table, this is a good place to | |
1187 | initialize this. */ | |
1188 | occr->copied_p = 0; | |
1189 | } | |
1190 | ||
1191 | /* While we're scanning the table, this is a good place to | |
1192 | initialize this. */ | |
1193 | expr->reaching_reg = 0; | |
1194 | } | |
1195 | } | |
1196 | } | |
1197 | \f | |
1198 | /* Register set information. | |
1199 | ||
1200 | `reg_set_table' records where each register is set or otherwise | |
1201 | modified. */ | |
1202 | ||
1203 | static struct obstack reg_set_obstack; | |
1204 | ||
1205 | static void | |
1206 | alloc_reg_set_mem (n_regs) | |
1207 | int n_regs; | |
1208 | { | |
1209 | unsigned int n; | |
1210 | ||
1211 | reg_set_table_size = n_regs + REG_SET_TABLE_SLOP; | |
1212 | n = reg_set_table_size * sizeof (struct reg_set *); | |
1213 | reg_set_table = (struct reg_set **) gmalloc (n); | |
1214 | memset ((char *) reg_set_table, 0, n); | |
1215 | ||
1216 | gcc_obstack_init (®_set_obstack); | |
1217 | } | |
1218 | ||
1219 | static void | |
1220 | free_reg_set_mem () | |
1221 | { | |
1222 | free (reg_set_table); | |
1223 | obstack_free (®_set_obstack, NULL); | |
1224 | } | |
1225 | ||
1226 | /* Record REGNO in the reg_set table. */ | |
1227 | ||
1228 | static void | |
1229 | record_one_set (regno, insn) | |
1230 | int regno; | |
1231 | rtx insn; | |
1232 | { | |
1233 | /* Allocate a new reg_set element and link it onto the list. */ | |
1234 | struct reg_set *new_reg_info; | |
1235 | ||
1236 | /* If the table isn't big enough, enlarge it. */ | |
1237 | if (regno >= reg_set_table_size) | |
1238 | { | |
1239 | int new_size = regno + REG_SET_TABLE_SLOP; | |
1240 | ||
1241 | reg_set_table | |
1242 | = (struct reg_set **) grealloc ((char *) reg_set_table, | |
1243 | new_size * sizeof (struct reg_set *)); | |
1244 | memset ((char *) (reg_set_table + reg_set_table_size), 0, | |
1245 | (new_size - reg_set_table_size) * sizeof (struct reg_set *)); | |
1246 | reg_set_table_size = new_size; | |
1247 | } | |
1248 | ||
1249 | new_reg_info = (struct reg_set *) obstack_alloc (®_set_obstack, | |
1250 | sizeof (struct reg_set)); | |
1251 | bytes_used += sizeof (struct reg_set); | |
1252 | new_reg_info->insn = insn; | |
1253 | new_reg_info->next = reg_set_table[regno]; | |
1254 | reg_set_table[regno] = new_reg_info; | |
1255 | } | |
1256 | ||
1257 | /* Called from compute_sets via note_stores to handle one SET or CLOBBER in | |
1258 | an insn. The DATA is really the instruction in which the SET is | |
1259 | occurring. */ | |
1260 | ||
1261 | static void | |
1262 | record_set_info (dest, setter, data) | |
1263 | rtx dest, setter ATTRIBUTE_UNUSED; | |
1264 | void *data; | |
1265 | { | |
1266 | rtx record_set_insn = (rtx) data; | |
1267 | ||
1268 | if (GET_CODE (dest) == REG && REGNO (dest) >= FIRST_PSEUDO_REGISTER) | |
1269 | record_one_set (REGNO (dest), record_set_insn); | |
1270 | } | |
1271 | ||
1272 | /* Scan the function and record each set of each pseudo-register. | |
1273 | ||
1274 | This is called once, at the start of the gcse pass. See the comments for | |
1275 | `reg_set_table' for further documenation. */ | |
1276 | ||
1277 | static void | |
1278 | compute_sets (f) | |
1279 | rtx f; | |
1280 | { | |
1281 | rtx insn; | |
1282 | ||
1283 | for (insn = f; insn != 0; insn = NEXT_INSN (insn)) | |
1284 | if (INSN_P (insn)) | |
1285 | note_stores (PATTERN (insn), record_set_info, insn); | |
1286 | } | |
1287 | \f | |
1288 | /* Hash table support. */ | |
1289 | ||
1290 | struct reg_avail_info | |
1291 | { | |
1292 | basic_block last_bb; | |
1293 | int first_set; | |
1294 | int last_set; | |
1295 | }; | |
1296 | ||
1297 | static struct reg_avail_info *reg_avail_info; | |
1298 | static basic_block current_bb; | |
1299 | ||
1300 | ||
1301 | /* See whether X, the source of a set, is something we want to consider for | |
1302 | GCSE. */ | |
1303 | ||
1304 | static GTY(()) rtx test_insn; | |
1305 | static int | |
1306 | want_to_gcse_p (x) | |
1307 | rtx x; | |
1308 | { | |
1309 | int num_clobbers = 0; | |
1310 | int icode; | |
1311 | ||
1312 | switch (GET_CODE (x)) | |
1313 | { | |
1314 | case REG: | |
1315 | case SUBREG: | |
1316 | case CONST_INT: | |
1317 | case CONST_DOUBLE: | |
1318 | case CONST_VECTOR: | |
1319 | case CALL: | |
1320 | return 0; | |
1321 | ||
1322 | default: | |
1323 | break; | |
1324 | } | |
1325 | ||
1326 | /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */ | |
1327 | if (general_operand (x, GET_MODE (x))) | |
1328 | return 1; | |
1329 | else if (GET_MODE (x) == VOIDmode) | |
1330 | return 0; | |
1331 | ||
1332 | /* Otherwise, check if we can make a valid insn from it. First initialize | |
1333 | our test insn if we haven't already. */ | |
1334 | if (test_insn == 0) | |
1335 | { | |
1336 | test_insn | |
1337 | = make_insn_raw (gen_rtx_SET (VOIDmode, | |
1338 | gen_rtx_REG (word_mode, | |
1339 | FIRST_PSEUDO_REGISTER * 2), | |
1340 | const0_rtx)); | |
1341 | NEXT_INSN (test_insn) = PREV_INSN (test_insn) = 0; | |
1342 | } | |
1343 | ||
1344 | /* Now make an insn like the one we would make when GCSE'ing and see if | |
1345 | valid. */ | |
1346 | PUT_MODE (SET_DEST (PATTERN (test_insn)), GET_MODE (x)); | |
1347 | SET_SRC (PATTERN (test_insn)) = x; | |
1348 | return ((icode = recog (PATTERN (test_insn), test_insn, &num_clobbers)) >= 0 | |
1349 | && (num_clobbers == 0 || ! added_clobbers_hard_reg_p (icode))); | |
1350 | } | |
1351 | ||
1352 | /* Return non-zero if the operands of expression X are unchanged from the | |
1353 | start of INSN's basic block up to but not including INSN (if AVAIL_P == 0), | |
1354 | or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */ | |
1355 | ||
1356 | static int | |
1357 | oprs_unchanged_p (x, insn, avail_p) | |
1358 | rtx x, insn; | |
1359 | int avail_p; | |
1360 | { | |
1361 | int i, j; | |
1362 | enum rtx_code code; | |
1363 | const char *fmt; | |
1364 | ||
1365 | if (x == 0) | |
1366 | return 1; | |
1367 | ||
1368 | code = GET_CODE (x); | |
1369 | switch (code) | |
1370 | { | |
1371 | case REG: | |
1372 | { | |
1373 | struct reg_avail_info *info = ®_avail_info[REGNO (x)]; | |
1374 | ||
1375 | if (info->last_bb != current_bb) | |
1376 | return 1; | |
1377 | if (avail_p) | |
1378 | return info->last_set < INSN_CUID (insn); | |
1379 | else | |
1380 | return info->first_set >= INSN_CUID (insn); | |
1381 | } | |
1382 | ||
1383 | case MEM: | |
1384 | if (load_killed_in_block_p (current_bb, INSN_CUID (insn), | |
1385 | x, avail_p)) | |
1386 | return 0; | |
1387 | else | |
1388 | return oprs_unchanged_p (XEXP (x, 0), insn, avail_p); | |
1389 | ||
1390 | case PRE_DEC: | |
1391 | case PRE_INC: | |
1392 | case POST_DEC: | |
1393 | case POST_INC: | |
1394 | case PRE_MODIFY: | |
1395 | case POST_MODIFY: | |
1396 | return 0; | |
1397 | ||
1398 | case PC: | |
1399 | case CC0: /*FIXME*/ | |
1400 | case CONST: | |
1401 | case CONST_INT: | |
1402 | case CONST_DOUBLE: | |
1403 | case CONST_VECTOR: | |
1404 | case SYMBOL_REF: | |
1405 | case LABEL_REF: | |
1406 | case ADDR_VEC: | |
1407 | case ADDR_DIFF_VEC: | |
1408 | return 1; | |
1409 | ||
1410 | default: | |
1411 | break; | |
1412 | } | |
1413 | ||
1414 | for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--) | |
1415 | { | |
1416 | if (fmt[i] == 'e') | |
1417 | { | |
1418 | /* If we are about to do the last recursive call needed at this | |
1419 | level, change it into iteration. This function is called enough | |
1420 | to be worth it. */ | |
1421 | if (i == 0) | |
1422 | return oprs_unchanged_p (XEXP (x, i), insn, avail_p); | |
1423 | ||
1424 | else if (! oprs_unchanged_p (XEXP (x, i), insn, avail_p)) | |
1425 | return 0; | |
1426 | } | |
1427 | else if (fmt[i] == 'E') | |
1428 | for (j = 0; j < XVECLEN (x, i); j++) | |
1429 | if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p)) | |
1430 | return 0; | |
1431 | } | |
1432 | ||
1433 | return 1; | |
1434 | } | |
1435 | ||
1436 | /* Used for communication between mems_conflict_for_gcse_p and | |
1437 | load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a | |
1438 | conflict between two memory references. */ | |
1439 | static int gcse_mems_conflict_p; | |
1440 | ||
1441 | /* Used for communication between mems_conflict_for_gcse_p and | |
1442 | load_killed_in_block_p. A memory reference for a load instruction, | |
1443 | mems_conflict_for_gcse_p will see if a memory store conflicts with | |
1444 | this memory load. */ | |
1445 | static rtx gcse_mem_operand; | |
1446 | ||
1447 | /* DEST is the output of an instruction. If it is a memory reference, and | |
1448 | possibly conflicts with the load found in gcse_mem_operand, then set | |
1449 | gcse_mems_conflict_p to a nonzero value. */ | |
1450 | ||
1451 | static void | |
1452 | mems_conflict_for_gcse_p (dest, setter, data) | |
1453 | rtx dest, setter ATTRIBUTE_UNUSED; | |
1454 | void *data ATTRIBUTE_UNUSED; | |
1455 | { | |
1456 | while (GET_CODE (dest) == SUBREG | |
1457 | || GET_CODE (dest) == ZERO_EXTRACT | |
1458 | || GET_CODE (dest) == SIGN_EXTRACT | |
1459 | || GET_CODE (dest) == STRICT_LOW_PART) | |
1460 | dest = XEXP (dest, 0); | |
1461 | ||
1462 | /* If DEST is not a MEM, then it will not conflict with the load. Note | |
1463 | that function calls are assumed to clobber memory, but are handled | |
1464 | elsewhere. */ | |
1465 | if (GET_CODE (dest) != MEM) | |
1466 | return; | |
1467 | ||
1468 | /* If we are setting a MEM in our list of specially recognized MEMs, | |
1469 | don't mark as killed this time. */ | |
1470 | ||
1471 | if (dest == gcse_mem_operand && pre_ldst_mems != NULL) | |
1472 | { | |
1473 | if (!find_rtx_in_ldst (dest)) | |
1474 | gcse_mems_conflict_p = 1; | |
1475 | return; | |
1476 | } | |
1477 | ||
1478 | if (true_dependence (dest, GET_MODE (dest), gcse_mem_operand, | |
1479 | rtx_addr_varies_p)) | |
1480 | gcse_mems_conflict_p = 1; | |
1481 | } | |
1482 | ||
1483 | /* Return nonzero if the expression in X (a memory reference) is killed | |
1484 | in block BB before or after the insn with the CUID in UID_LIMIT. | |
1485 | AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills | |
1486 | before UID_LIMIT. | |
1487 | ||
1488 | To check the entire block, set UID_LIMIT to max_uid + 1 and | |
1489 | AVAIL_P to 0. */ | |
1490 | ||
1491 | static int | |
1492 | load_killed_in_block_p (bb, uid_limit, x, avail_p) | |
1493 | basic_block bb; | |
1494 | int uid_limit; | |
1495 | rtx x; | |
1496 | int avail_p; | |
1497 | { | |
1498 | rtx list_entry = modify_mem_list[bb->index]; | |
1499 | while (list_entry) | |
1500 | { | |
1501 | rtx setter; | |
1502 | /* Ignore entries in the list that do not apply. */ | |
1503 | if ((avail_p | |
1504 | && INSN_CUID (XEXP (list_entry, 0)) < uid_limit) | |
1505 | || (! avail_p | |
1506 | && INSN_CUID (XEXP (list_entry, 0)) > uid_limit)) | |
1507 | { | |
1508 | list_entry = XEXP (list_entry, 1); | |
1509 | continue; | |
1510 | } | |
1511 | ||
1512 | setter = XEXP (list_entry, 0); | |
1513 | ||
1514 | /* If SETTER is a call everything is clobbered. Note that calls | |
1515 | to pure functions are never put on the list, so we need not | |
1516 | worry about them. */ | |
1517 | if (GET_CODE (setter) == CALL_INSN) | |
1518 | return 1; | |
1519 | ||
1520 | /* SETTER must be an INSN of some kind that sets memory. Call | |
1521 | note_stores to examine each hunk of memory that is modified. | |
1522 | ||
1523 | The note_stores interface is pretty limited, so we have to | |
1524 | communicate via global variables. Yuk. */ | |
1525 | gcse_mem_operand = x; | |
1526 | gcse_mems_conflict_p = 0; | |
1527 | note_stores (PATTERN (setter), mems_conflict_for_gcse_p, NULL); | |
1528 | if (gcse_mems_conflict_p) | |
1529 | return 1; | |
1530 | list_entry = XEXP (list_entry, 1); | |
1531 | } | |
1532 | return 0; | |
1533 | } | |
1534 | ||
1535 | /* Return non-zero if the operands of expression X are unchanged from | |
1536 | the start of INSN's basic block up to but not including INSN. */ | |
1537 | ||
1538 | static int | |
1539 | oprs_anticipatable_p (x, insn) | |
1540 | rtx x, insn; | |
1541 | { | |
1542 | return oprs_unchanged_p (x, insn, 0); | |
1543 | } | |
1544 | ||
1545 | /* Return non-zero if the operands of expression X are unchanged from | |
1546 | INSN to the end of INSN's basic block. */ | |
1547 | ||
1548 | static int | |
1549 | oprs_available_p (x, insn) | |
1550 | rtx x, insn; | |
1551 | { | |
1552 | return oprs_unchanged_p (x, insn, 1); | |
1553 | } | |
1554 | ||
1555 | /* Hash expression X. | |
1556 | ||
1557 | MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean | |
1558 | indicating if a volatile operand is found or if the expression contains | |
1559 | something we don't want to insert in the table. | |
1560 | ||
1561 | ??? One might want to merge this with canon_hash. Later. */ | |
1562 | ||
1563 | static unsigned int | |
1564 | hash_expr (x, mode, do_not_record_p, hash_table_size) | |
1565 | rtx x; | |
1566 | enum machine_mode mode; | |
1567 | int *do_not_record_p; | |
1568 | int hash_table_size; | |
1569 | { | |
1570 | unsigned int hash; | |
1571 | ||
1572 | *do_not_record_p = 0; | |
1573 | ||
1574 | hash = hash_expr_1 (x, mode, do_not_record_p); | |
1575 | return hash % hash_table_size; | |
1576 | } | |
1577 | ||
1578 | /* Hash a string. Just add its bytes up. */ | |
1579 | ||
1580 | static inline unsigned | |
1581 | hash_string_1 (ps) | |
1582 | const char *ps; | |
1583 | { | |
1584 | unsigned hash = 0; | |
1585 | const unsigned char *p = (const unsigned char *) ps; | |
1586 | ||
1587 | if (p) | |
1588 | while (*p) | |
1589 | hash += *p++; | |
1590 | ||
1591 | return hash; | |
1592 | } | |
1593 | ||
1594 | /* Subroutine of hash_expr to do the actual work. */ | |
1595 | ||
1596 | static unsigned int | |
1597 | hash_expr_1 (x, mode, do_not_record_p) | |
1598 | rtx x; | |
1599 | enum machine_mode mode; | |
1600 | int *do_not_record_p; | |
1601 | { | |
1602 | int i, j; | |
1603 | unsigned hash = 0; | |
1604 | enum rtx_code code; | |
1605 | const char *fmt; | |
1606 | ||
1607 | /* Used to turn recursion into iteration. We can't rely on GCC's | |
1608 | tail-recursion eliminatio since we need to keep accumulating values | |
1609 | in HASH. */ | |
1610 | ||
1611 | if (x == 0) | |
1612 | return hash; | |
1613 | ||
1614 | repeat: | |
1615 | code = GET_CODE (x); | |
1616 | switch (code) | |
1617 | { | |
1618 | case REG: | |
1619 | hash += ((unsigned int) REG << 7) + REGNO (x); | |
1620 | return hash; | |
1621 | ||
1622 | case CONST_INT: | |
1623 | hash += (((unsigned int) CONST_INT << 7) + (unsigned int) mode | |
1624 | + (unsigned int) INTVAL (x)); | |
1625 | return hash; | |
1626 | ||
1627 | case CONST_DOUBLE: | |
1628 | /* This is like the general case, except that it only counts | |
1629 | the integers representing the constant. */ | |
1630 | hash += (unsigned int) code + (unsigned int) GET_MODE (x); | |
1631 | if (GET_MODE (x) != VOIDmode) | |
1632 | for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++) | |
1633 | hash += (unsigned int) XWINT (x, i); | |
1634 | else | |
1635 | hash += ((unsigned int) CONST_DOUBLE_LOW (x) | |
1636 | + (unsigned int) CONST_DOUBLE_HIGH (x)); | |
1637 | return hash; | |
1638 | ||
1639 | case CONST_VECTOR: | |
1640 | { | |
1641 | int units; | |
1642 | rtx elt; | |
1643 | ||
1644 | units = CONST_VECTOR_NUNITS (x); | |
1645 | ||
1646 | for (i = 0; i < units; ++i) | |
1647 | { | |
1648 | elt = CONST_VECTOR_ELT (x, i); | |
1649 | hash += hash_expr_1 (elt, GET_MODE (elt), do_not_record_p); | |
1650 | } | |
1651 | ||
1652 | return hash; | |
1653 | } | |
1654 | ||
1655 | /* Assume there is only one rtx object for any given label. */ | |
1656 | case LABEL_REF: | |
1657 | /* We don't hash on the address of the CODE_LABEL to avoid bootstrap | |
1658 | differences and differences between each stage's debugging dumps. */ | |
1659 | hash += (((unsigned int) LABEL_REF << 7) | |
1660 | + CODE_LABEL_NUMBER (XEXP (x, 0))); | |
1661 | return hash; | |
1662 | ||
1663 | case SYMBOL_REF: | |
1664 | { | |
1665 | /* Don't hash on the symbol's address to avoid bootstrap differences. | |
1666 | Different hash values may cause expressions to be recorded in | |
1667 | different orders and thus different registers to be used in the | |
1668 | final assembler. This also avoids differences in the dump files | |
1669 | between various stages. */ | |
1670 | unsigned int h = 0; | |
1671 | const unsigned char *p = (const unsigned char *) XSTR (x, 0); | |
1672 | ||
1673 | while (*p) | |
1674 | h += (h << 7) + *p++; /* ??? revisit */ | |
1675 | ||
1676 | hash += ((unsigned int) SYMBOL_REF << 7) + h; | |
1677 | return hash; | |
1678 | } | |
1679 | ||
1680 | case MEM: | |
1681 | if (MEM_VOLATILE_P (x)) | |
1682 | { | |
1683 | *do_not_record_p = 1; | |
1684 | return 0; | |
1685 | } | |
1686 | ||
1687 | hash += (unsigned int) MEM; | |
1688 | /* We used alias set for hashing, but this is not good, since the alias | |
1689 | set may differ in -fprofile-arcs and -fbranch-probabilities compilation | |
1690 | causing the profiles to fail to match. */ | |
1691 | x = XEXP (x, 0); | |
1692 | goto repeat; | |
1693 | ||
1694 | case PRE_DEC: | |
1695 | case PRE_INC: | |
1696 | case POST_DEC: | |
1697 | case POST_INC: | |
1698 | case PC: | |
1699 | case CC0: | |
1700 | case CALL: | |
1701 | case UNSPEC_VOLATILE: | |
1702 | *do_not_record_p = 1; | |
1703 | return 0; | |
1704 | ||
1705 | case ASM_OPERANDS: | |
1706 | if (MEM_VOLATILE_P (x)) | |
1707 | { | |
1708 | *do_not_record_p = 1; | |
1709 | return 0; | |
1710 | } | |
1711 | else | |
1712 | { | |
1713 | /* We don't want to take the filename and line into account. */ | |
1714 | hash += (unsigned) code + (unsigned) GET_MODE (x) | |
1715 | + hash_string_1 (ASM_OPERANDS_TEMPLATE (x)) | |
1716 | + hash_string_1 (ASM_OPERANDS_OUTPUT_CONSTRAINT (x)) | |
1717 | + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x); | |
1718 | ||
1719 | if (ASM_OPERANDS_INPUT_LENGTH (x)) | |
1720 | { | |
1721 | for (i = 1; i < ASM_OPERANDS_INPUT_LENGTH (x); i++) | |
1722 | { | |
1723 | hash += (hash_expr_1 (ASM_OPERANDS_INPUT (x, i), | |
1724 | GET_MODE (ASM_OPERANDS_INPUT (x, i)), | |
1725 | do_not_record_p) | |
1726 | + hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT | |
1727 | (x, i))); | |
1728 | } | |
1729 | ||
1730 | hash += hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT (x, 0)); | |
1731 | x = ASM_OPERANDS_INPUT (x, 0); | |
1732 | mode = GET_MODE (x); | |
1733 | goto repeat; | |
1734 | } | |
1735 | return hash; | |
1736 | } | |
1737 | ||
1738 | default: | |
1739 | break; | |
1740 | } | |
1741 | ||
1742 | hash += (unsigned) code + (unsigned) GET_MODE (x); | |
1743 | for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--) | |
1744 | { | |
1745 | if (fmt[i] == 'e') | |
1746 | { | |
1747 | /* If we are about to do the last recursive call | |
1748 | needed at this level, change it into iteration. | |
1749 | This function is called enough to be worth it. */ | |
1750 | if (i == 0) | |
1751 | { | |
1752 | x = XEXP (x, i); | |
1753 | goto repeat; | |
1754 | } | |
1755 | ||
1756 | hash += hash_expr_1 (XEXP (x, i), 0, do_not_record_p); | |
1757 | if (*do_not_record_p) | |
1758 | return 0; | |
1759 | } | |
1760 | ||
1761 | else if (fmt[i] == 'E') | |
1762 | for (j = 0; j < XVECLEN (x, i); j++) | |
1763 | { | |
1764 | hash += hash_expr_1 (XVECEXP (x, i, j), 0, do_not_record_p); | |
1765 | if (*do_not_record_p) | |
1766 | return 0; | |
1767 | } | |
1768 | ||
1769 | else if (fmt[i] == 's') | |
1770 | hash += hash_string_1 (XSTR (x, i)); | |
1771 | else if (fmt[i] == 'i') | |
1772 | hash += (unsigned int) XINT (x, i); | |
1773 | else | |
1774 | abort (); | |
1775 | } | |
1776 | ||
1777 | return hash; | |
1778 | } | |
1779 | ||
1780 | /* Hash a set of register REGNO. | |
1781 | ||
1782 | Sets are hashed on the register that is set. This simplifies the PRE copy | |
1783 | propagation code. | |
1784 | ||
1785 | ??? May need to make things more elaborate. Later, as necessary. */ | |
1786 | ||
1787 | static unsigned int | |
1788 | hash_set (regno, hash_table_size) | |
1789 | int regno; | |
1790 | int hash_table_size; | |
1791 | { | |
1792 | unsigned int hash; | |
1793 | ||
1794 | hash = regno; | |
1795 | return hash % hash_table_size; | |
1796 | } | |
1797 | ||
1798 | /* Return non-zero if exp1 is equivalent to exp2. | |
1799 | ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */ | |
1800 | ||
1801 | static int | |
1802 | expr_equiv_p (x, y) | |
1803 | rtx x, y; | |
1804 | { | |
1805 | int i, j; | |
1806 | enum rtx_code code; | |
1807 | const char *fmt; | |
1808 | ||
1809 | if (x == y) | |
1810 | return 1; | |
1811 | ||
1812 | if (x == 0 || y == 0) | |
1813 | return x == y; | |
1814 | ||
1815 | code = GET_CODE (x); | |
1816 | if (code != GET_CODE (y)) | |
1817 | return 0; | |
1818 | ||
1819 | /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */ | |
1820 | if (GET_MODE (x) != GET_MODE (y)) | |
1821 | return 0; | |
1822 | ||
1823 | switch (code) | |
1824 | { | |
1825 | case PC: | |
1826 | case CC0: | |
1827 | return x == y; | |
1828 | ||
1829 | case CONST_INT: | |
1830 | return INTVAL (x) == INTVAL (y); | |
1831 | ||
1832 | case LABEL_REF: | |
1833 | return XEXP (x, 0) == XEXP (y, 0); | |
1834 | ||
1835 | case SYMBOL_REF: | |
1836 | return XSTR (x, 0) == XSTR (y, 0); | |
1837 | ||
1838 | case REG: | |
1839 | return REGNO (x) == REGNO (y); | |
1840 | ||
1841 | case MEM: | |
1842 | /* Can't merge two expressions in different alias sets, since we can | |
1843 | decide that the expression is transparent in a block when it isn't, | |
1844 | due to it being set with the different alias set. */ | |
1845 | if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y)) | |
1846 | return 0; | |
1847 | break; | |
1848 | ||
1849 | /* For commutative operations, check both orders. */ | |
1850 | case PLUS: | |
1851 | case MULT: | |
1852 | case AND: | |
1853 | case IOR: | |
1854 | case XOR: | |
1855 | case NE: | |
1856 | case EQ: | |
1857 | return ((expr_equiv_p (XEXP (x, 0), XEXP (y, 0)) | |
1858 | && expr_equiv_p (XEXP (x, 1), XEXP (y, 1))) | |
1859 | || (expr_equiv_p (XEXP (x, 0), XEXP (y, 1)) | |
1860 | && expr_equiv_p (XEXP (x, 1), XEXP (y, 0)))); | |
1861 | ||
1862 | case ASM_OPERANDS: | |
1863 | /* We don't use the generic code below because we want to | |
1864 | disregard filename and line numbers. */ | |
1865 | ||
1866 | /* A volatile asm isn't equivalent to any other. */ | |
1867 | if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y)) | |
1868 | return 0; | |
1869 | ||
1870 | if (GET_MODE (x) != GET_MODE (y) | |
1871 | || strcmp (ASM_OPERANDS_TEMPLATE (x), ASM_OPERANDS_TEMPLATE (y)) | |
1872 | || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x), | |
1873 | ASM_OPERANDS_OUTPUT_CONSTRAINT (y)) | |
1874 | || ASM_OPERANDS_OUTPUT_IDX (x) != ASM_OPERANDS_OUTPUT_IDX (y) | |
1875 | || ASM_OPERANDS_INPUT_LENGTH (x) != ASM_OPERANDS_INPUT_LENGTH (y)) | |
1876 | return 0; | |
1877 | ||
1878 | if (ASM_OPERANDS_INPUT_LENGTH (x)) | |
1879 | { | |
1880 | for (i = ASM_OPERANDS_INPUT_LENGTH (x) - 1; i >= 0; i--) | |
1881 | if (! expr_equiv_p (ASM_OPERANDS_INPUT (x, i), | |
1882 | ASM_OPERANDS_INPUT (y, i)) | |
1883 | || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x, i), | |
1884 | ASM_OPERANDS_INPUT_CONSTRAINT (y, i))) | |
1885 | return 0; | |
1886 | } | |
1887 | ||
1888 | return 1; | |
1889 | ||
1890 | default: | |
1891 | break; | |
1892 | } | |
1893 | ||
1894 | /* Compare the elements. If any pair of corresponding elements | |
1895 | fail to match, return 0 for the whole thing. */ | |
1896 | ||
1897 | fmt = GET_RTX_FORMAT (code); | |
1898 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
1899 | { | |
1900 | switch (fmt[i]) | |
1901 | { | |
1902 | case 'e': | |
1903 | if (! expr_equiv_p (XEXP (x, i), XEXP (y, i))) | |
1904 | return 0; | |
1905 | break; | |
1906 | ||
1907 | case 'E': | |
1908 | if (XVECLEN (x, i) != XVECLEN (y, i)) | |
1909 | return 0; | |
1910 | for (j = 0; j < XVECLEN (x, i); j++) | |
1911 | if (! expr_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j))) | |
1912 | return 0; | |
1913 | break; | |
1914 | ||
1915 | case 's': | |
1916 | if (strcmp (XSTR (x, i), XSTR (y, i))) | |
1917 | return 0; | |
1918 | break; | |
1919 | ||
1920 | case 'i': | |
1921 | if (XINT (x, i) != XINT (y, i)) | |
1922 | return 0; | |
1923 | break; | |
1924 | ||
1925 | case 'w': | |
1926 | if (XWINT (x, i) != XWINT (y, i)) | |
1927 | return 0; | |
1928 | break; | |
1929 | ||
1930 | case '0': | |
1931 | break; | |
1932 | ||
1933 | default: | |
1934 | abort (); | |
1935 | } | |
1936 | } | |
1937 | ||
1938 | return 1; | |
1939 | } | |
1940 | ||
1941 | /* Insert expression X in INSN in the hash table. | |
1942 | If it is already present, record it as the last occurrence in INSN's | |
1943 | basic block. | |
1944 | ||
1945 | MODE is the mode of the value X is being stored into. | |
1946 | It is only used if X is a CONST_INT. | |
1947 | ||
1948 | ANTIC_P is non-zero if X is an anticipatable expression. | |
1949 | AVAIL_P is non-zero if X is an available expression. */ | |
1950 | ||
1951 | static void | |
1952 | insert_expr_in_table (x, mode, insn, antic_p, avail_p) | |
1953 | rtx x; | |
1954 | enum machine_mode mode; | |
1955 | rtx insn; | |
1956 | int antic_p, avail_p; | |
1957 | { | |
1958 | int found, do_not_record_p; | |
1959 | unsigned int hash; | |
1960 | struct expr *cur_expr, *last_expr = NULL; | |
1961 | struct occr *antic_occr, *avail_occr; | |
1962 | struct occr *last_occr = NULL; | |
1963 | ||
1964 | hash = hash_expr (x, mode, &do_not_record_p, expr_hash_table_size); | |
1965 | ||
1966 | /* Do not insert expression in table if it contains volatile operands, | |
1967 | or if hash_expr determines the expression is something we don't want | |
1968 | to or can't handle. */ | |
1969 | if (do_not_record_p) | |
1970 | return; | |
1971 | ||
1972 | cur_expr = expr_hash_table[hash]; | |
1973 | found = 0; | |
1974 | ||
1975 | while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x))) | |
1976 | { | |
1977 | /* If the expression isn't found, save a pointer to the end of | |
1978 | the list. */ | |
1979 | last_expr = cur_expr; | |
1980 | cur_expr = cur_expr->next_same_hash; | |
1981 | } | |
1982 | ||
1983 | if (! found) | |
1984 | { | |
1985 | cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr)); | |
1986 | bytes_used += sizeof (struct expr); | |
1987 | if (expr_hash_table[hash] == NULL) | |
1988 | /* This is the first pattern that hashed to this index. */ | |
1989 | expr_hash_table[hash] = cur_expr; | |
1990 | else | |
1991 | /* Add EXPR to end of this hash chain. */ | |
1992 | last_expr->next_same_hash = cur_expr; | |
1993 | ||
1994 | /* Set the fields of the expr element. */ | |
1995 | cur_expr->expr = x; | |
1996 | cur_expr->bitmap_index = n_exprs++; | |
1997 | cur_expr->next_same_hash = NULL; | |
1998 | cur_expr->antic_occr = NULL; | |
1999 | cur_expr->avail_occr = NULL; | |
2000 | } | |
2001 | ||
2002 | /* Now record the occurrence(s). */ | |
2003 | if (antic_p) | |
2004 | { | |
2005 | antic_occr = cur_expr->antic_occr; | |
2006 | ||
2007 | /* Search for another occurrence in the same basic block. */ | |
2008 | while (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn)) | |
2009 | { | |
2010 | /* If an occurrence isn't found, save a pointer to the end of | |
2011 | the list. */ | |
2012 | last_occr = antic_occr; | |
2013 | antic_occr = antic_occr->next; | |
2014 | } | |
2015 | ||
2016 | if (antic_occr) | |
2017 | /* Found another instance of the expression in the same basic block. | |
2018 | Prefer the currently recorded one. We want the first one in the | |
2019 | block and the block is scanned from start to end. */ | |
2020 | ; /* nothing to do */ | |
2021 | else | |
2022 | { | |
2023 | /* First occurrence of this expression in this basic block. */ | |
2024 | antic_occr = (struct occr *) gcse_alloc (sizeof (struct occr)); | |
2025 | bytes_used += sizeof (struct occr); | |
2026 | /* First occurrence of this expression in any block? */ | |
2027 | if (cur_expr->antic_occr == NULL) | |
2028 | cur_expr->antic_occr = antic_occr; | |
2029 | else | |
2030 | last_occr->next = antic_occr; | |
2031 | ||
2032 | antic_occr->insn = insn; | |
2033 | antic_occr->next = NULL; | |
2034 | } | |
2035 | } | |
2036 | ||
2037 | if (avail_p) | |
2038 | { | |
2039 | avail_occr = cur_expr->avail_occr; | |
2040 | ||
2041 | /* Search for another occurrence in the same basic block. */ | |
2042 | while (avail_occr && BLOCK_NUM (avail_occr->insn) != BLOCK_NUM (insn)) | |
2043 | { | |
2044 | /* If an occurrence isn't found, save a pointer to the end of | |
2045 | the list. */ | |
2046 | last_occr = avail_occr; | |
2047 | avail_occr = avail_occr->next; | |
2048 | } | |
2049 | ||
2050 | if (avail_occr) | |
2051 | /* Found another instance of the expression in the same basic block. | |
2052 | Prefer this occurrence to the currently recorded one. We want | |
2053 | the last one in the block and the block is scanned from start | |
2054 | to end. */ | |
2055 | avail_occr->insn = insn; | |
2056 | else | |
2057 | { | |
2058 | /* First occurrence of this expression in this basic block. */ | |
2059 | avail_occr = (struct occr *) gcse_alloc (sizeof (struct occr)); | |
2060 | bytes_used += sizeof (struct occr); | |
2061 | ||
2062 | /* First occurrence of this expression in any block? */ | |
2063 | if (cur_expr->avail_occr == NULL) | |
2064 | cur_expr->avail_occr = avail_occr; | |
2065 | else | |
2066 | last_occr->next = avail_occr; | |
2067 | ||
2068 | avail_occr->insn = insn; | |
2069 | avail_occr->next = NULL; | |
2070 | } | |
2071 | } | |
2072 | } | |
2073 | ||
2074 | /* Insert pattern X in INSN in the hash table. | |
2075 | X is a SET of a reg to either another reg or a constant. | |
2076 | If it is already present, record it as the last occurrence in INSN's | |
2077 | basic block. */ | |
2078 | ||
2079 | static void | |
2080 | insert_set_in_table (x, insn) | |
2081 | rtx x; | |
2082 | rtx insn; | |
2083 | { | |
2084 | int found; | |
2085 | unsigned int hash; | |
2086 | struct expr *cur_expr, *last_expr = NULL; | |
2087 | struct occr *cur_occr, *last_occr = NULL; | |
2088 | ||
2089 | if (GET_CODE (x) != SET | |
2090 | || GET_CODE (SET_DEST (x)) != REG) | |
2091 | abort (); | |
2092 | ||
2093 | hash = hash_set (REGNO (SET_DEST (x)), set_hash_table_size); | |
2094 | ||
2095 | cur_expr = set_hash_table[hash]; | |
2096 | found = 0; | |
2097 | ||
2098 | while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x))) | |
2099 | { | |
2100 | /* If the expression isn't found, save a pointer to the end of | |
2101 | the list. */ | |
2102 | last_expr = cur_expr; | |
2103 | cur_expr = cur_expr->next_same_hash; | |
2104 | } | |
2105 | ||
2106 | if (! found) | |
2107 | { | |
2108 | cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr)); | |
2109 | bytes_used += sizeof (struct expr); | |
2110 | if (set_hash_table[hash] == NULL) | |
2111 | /* This is the first pattern that hashed to this index. */ | |
2112 | set_hash_table[hash] = cur_expr; | |
2113 | else | |
2114 | /* Add EXPR to end of this hash chain. */ | |
2115 | last_expr->next_same_hash = cur_expr; | |
2116 | ||
2117 | /* Set the fields of the expr element. | |
2118 | We must copy X because it can be modified when copy propagation is | |
2119 | performed on its operands. */ | |
2120 | cur_expr->expr = copy_rtx (x); | |
2121 | cur_expr->bitmap_index = n_sets++; | |
2122 | cur_expr->next_same_hash = NULL; | |
2123 | cur_expr->antic_occr = NULL; | |
2124 | cur_expr->avail_occr = NULL; | |
2125 | } | |
2126 | ||
2127 | /* Now record the occurrence. */ | |
2128 | cur_occr = cur_expr->avail_occr; | |
2129 | ||
2130 | /* Search for another occurrence in the same basic block. */ | |
2131 | while (cur_occr && BLOCK_NUM (cur_occr->insn) != BLOCK_NUM (insn)) | |
2132 | { | |
2133 | /* If an occurrence isn't found, save a pointer to the end of | |
2134 | the list. */ | |
2135 | last_occr = cur_occr; | |
2136 | cur_occr = cur_occr->next; | |
2137 | } | |
2138 | ||
2139 | if (cur_occr) | |
2140 | /* Found another instance of the expression in the same basic block. | |
2141 | Prefer this occurrence to the currently recorded one. We want the | |
2142 | last one in the block and the block is scanned from start to end. */ | |
2143 | cur_occr->insn = insn; | |
2144 | else | |
2145 | { | |
2146 | /* First occurrence of this expression in this basic block. */ | |
2147 | cur_occr = (struct occr *) gcse_alloc (sizeof (struct occr)); | |
2148 | bytes_used += sizeof (struct occr); | |
2149 | ||
2150 | /* First occurrence of this expression in any block? */ | |
2151 | if (cur_expr->avail_occr == NULL) | |
2152 | cur_expr->avail_occr = cur_occr; | |
2153 | else | |
2154 | last_occr->next = cur_occr; | |
2155 | ||
2156 | cur_occr->insn = insn; | |
2157 | cur_occr->next = NULL; | |
2158 | } | |
2159 | } | |
2160 | ||
2161 | /* Scan pattern PAT of INSN and add an entry to the hash table. If SET_P is | |
2162 | non-zero, this is for the assignment hash table, otherwise it is for the | |
2163 | expression hash table. */ | |
2164 | ||
2165 | static void | |
2166 | hash_scan_set (pat, insn, set_p) | |
2167 | rtx pat, insn; | |
2168 | int set_p; | |
2169 | { | |
2170 | rtx src = SET_SRC (pat); | |
2171 | rtx dest = SET_DEST (pat); | |
2172 | rtx note; | |
2173 | ||
2174 | if (GET_CODE (src) == CALL) | |
2175 | hash_scan_call (src, insn); | |
2176 | ||
2177 | else if (GET_CODE (dest) == REG) | |
2178 | { | |
2179 | unsigned int regno = REGNO (dest); | |
2180 | rtx tmp; | |
2181 | ||
2182 | /* If this is a single set and we are doing constant propagation, | |
2183 | see if a REG_NOTE shows this equivalent to a constant. */ | |
2184 | if (set_p && (note = find_reg_equal_equiv_note (insn)) != 0 | |
2185 | && CONSTANT_P (XEXP (note, 0))) | |
2186 | src = XEXP (note, 0), pat = gen_rtx_SET (VOIDmode, dest, src); | |
2187 | ||
2188 | /* Only record sets of pseudo-regs in the hash table. */ | |
2189 | if (! set_p | |
2190 | && regno >= FIRST_PSEUDO_REGISTER | |
2191 | /* Don't GCSE something if we can't do a reg/reg copy. */ | |
2192 | && can_copy_p [GET_MODE (dest)] | |
2193 | /* GCSE commonly inserts instruction after the insn. We can't | |
2194 | do that easily for EH_REGION notes so disable GCSE on these | |
2195 | for now. */ | |
2196 | && !find_reg_note (insn, REG_EH_REGION, NULL_RTX) | |
2197 | /* Is SET_SRC something we want to gcse? */ | |
2198 | && want_to_gcse_p (src) | |
2199 | /* Don't CSE a nop. */ | |
2200 | && ! set_noop_p (pat) | |
2201 | /* Don't GCSE if it has attached REG_EQUIV note. | |
2202 | At this point this only function parameters should have | |
2203 | REG_EQUIV notes and if the argument slot is used somewhere | |
2204 | explicitly, it means address of parameter has been taken, | |
2205 | so we should not extend the lifetime of the pseudo. */ | |
2206 | && ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0 | |
2207 | || GET_CODE (XEXP (note, 0)) != MEM)) | |
2208 | { | |
2209 | /* An expression is not anticipatable if its operands are | |
2210 | modified before this insn or if this is not the only SET in | |
2211 | this insn. */ | |
2212 | int antic_p = oprs_anticipatable_p (src, insn) && single_set (insn); | |
2213 | /* An expression is not available if its operands are | |
2214 | subsequently modified, including this insn. It's also not | |
2215 | available if this is a branch, because we can't insert | |
2216 | a set after the branch. */ | |
2217 | int avail_p = (oprs_available_p (src, insn) | |
2218 | && ! JUMP_P (insn)); | |
2219 | ||
2220 | insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p); | |
2221 | } | |
2222 | ||
2223 | /* Record sets for constant/copy propagation. */ | |
2224 | else if (set_p | |
2225 | && regno >= FIRST_PSEUDO_REGISTER | |
2226 | && ((GET_CODE (src) == REG | |
2227 | && REGNO (src) >= FIRST_PSEUDO_REGISTER | |
2228 | && can_copy_p [GET_MODE (dest)] | |
2229 | && REGNO (src) != regno) | |
2230 | || CONSTANT_P (src)) | |
2231 | /* A copy is not available if its src or dest is subsequently | |
2232 | modified. Here we want to search from INSN+1 on, but | |
2233 | oprs_available_p searches from INSN on. */ | |
2234 | && (insn == BLOCK_END (BLOCK_NUM (insn)) | |
2235 | || ((tmp = next_nonnote_insn (insn)) != NULL_RTX | |
2236 | && oprs_available_p (pat, tmp)))) | |
2237 | insert_set_in_table (pat, insn); | |
2238 | } | |
2239 | } | |
2240 | ||
2241 | static void | |
2242 | hash_scan_clobber (x, insn) | |
2243 | rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED; | |
2244 | { | |
2245 | /* Currently nothing to do. */ | |
2246 | } | |
2247 | ||
2248 | static void | |
2249 | hash_scan_call (x, insn) | |
2250 | rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED; | |
2251 | { | |
2252 | /* Currently nothing to do. */ | |
2253 | } | |
2254 | ||
2255 | /* Process INSN and add hash table entries as appropriate. | |
2256 | ||
2257 | Only available expressions that set a single pseudo-reg are recorded. | |
2258 | ||
2259 | Single sets in a PARALLEL could be handled, but it's an extra complication | |
2260 | that isn't dealt with right now. The trick is handling the CLOBBERs that | |
2261 | are also in the PARALLEL. Later. | |
2262 | ||
2263 | If SET_P is non-zero, this is for the assignment hash table, | |
2264 | otherwise it is for the expression hash table. | |
2265 | If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should | |
2266 | not record any expressions. */ | |
2267 | ||
2268 | static void | |
2269 | hash_scan_insn (insn, set_p, in_libcall_block) | |
2270 | rtx insn; | |
2271 | int set_p; | |
2272 | int in_libcall_block; | |
2273 | { | |
2274 | rtx pat = PATTERN (insn); | |
2275 | int i; | |
2276 | ||
2277 | if (in_libcall_block) | |
2278 | return; | |
2279 | ||
2280 | /* Pick out the sets of INSN and for other forms of instructions record | |
2281 | what's been modified. */ | |
2282 | ||
2283 | if (GET_CODE (pat) == SET) | |
2284 | hash_scan_set (pat, insn, set_p); | |
2285 | else if (GET_CODE (pat) == PARALLEL) | |
2286 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
2287 | { | |
2288 | rtx x = XVECEXP (pat, 0, i); | |
2289 | ||
2290 | if (GET_CODE (x) == SET) | |
2291 | hash_scan_set (x, insn, set_p); | |
2292 | else if (GET_CODE (x) == CLOBBER) | |
2293 | hash_scan_clobber (x, insn); | |
2294 | else if (GET_CODE (x) == CALL) | |
2295 | hash_scan_call (x, insn); | |
2296 | } | |
2297 | ||
2298 | else if (GET_CODE (pat) == CLOBBER) | |
2299 | hash_scan_clobber (pat, insn); | |
2300 | else if (GET_CODE (pat) == CALL) | |
2301 | hash_scan_call (pat, insn); | |
2302 | } | |
2303 | ||
2304 | static void | |
2305 | dump_hash_table (file, name, table, table_size, total_size) | |
2306 | FILE *file; | |
2307 | const char *name; | |
2308 | struct expr **table; | |
2309 | int table_size, total_size; | |
2310 | { | |
2311 | int i; | |
2312 | /* Flattened out table, so it's printed in proper order. */ | |
2313 | struct expr **flat_table; | |
2314 | unsigned int *hash_val; | |
2315 | struct expr *expr; | |
2316 | ||
2317 | flat_table | |
2318 | = (struct expr **) xcalloc (total_size, sizeof (struct expr *)); | |
2319 | hash_val = (unsigned int *) xmalloc (total_size * sizeof (unsigned int)); | |
2320 | ||
2321 | for (i = 0; i < table_size; i++) | |
2322 | for (expr = table[i]; expr != NULL; expr = expr->next_same_hash) | |
2323 | { | |
2324 | flat_table[expr->bitmap_index] = expr; | |
2325 | hash_val[expr->bitmap_index] = i; | |
2326 | } | |
2327 | ||
2328 | fprintf (file, "%s hash table (%d buckets, %d entries)\n", | |
2329 | name, table_size, total_size); | |
2330 | ||
2331 | for (i = 0; i < total_size; i++) | |
2332 | if (flat_table[i] != 0) | |
2333 | { | |
2334 | expr = flat_table[i]; | |
2335 | fprintf (file, "Index %d (hash value %d)\n ", | |
2336 | expr->bitmap_index, hash_val[i]); | |
2337 | print_rtl (file, expr->expr); | |
2338 | fprintf (file, "\n"); | |
2339 | } | |
2340 | ||
2341 | fprintf (file, "\n"); | |
2342 | ||
2343 | free (flat_table); | |
2344 | free (hash_val); | |
2345 | } | |
2346 | ||
2347 | /* Record register first/last/block set information for REGNO in INSN. | |
2348 | ||
2349 | first_set records the first place in the block where the register | |
2350 | is set and is used to compute "anticipatability". | |
2351 | ||
2352 | last_set records the last place in the block where the register | |
2353 | is set and is used to compute "availability". | |
2354 | ||
2355 | last_bb records the block for which first_set and last_set are | |
2356 | valid, as a quick test to invalidate them. | |
2357 | ||
2358 | reg_set_in_block records whether the register is set in the block | |
2359 | and is used to compute "transparency". */ | |
2360 | ||
2361 | static void | |
2362 | record_last_reg_set_info (insn, regno) | |
2363 | rtx insn; | |
2364 | int regno; | |
2365 | { | |
2366 | struct reg_avail_info *info = ®_avail_info[regno]; | |
2367 | int cuid = INSN_CUID (insn); | |
2368 | ||
2369 | info->last_set = cuid; | |
2370 | if (info->last_bb != current_bb) | |
2371 | { | |
2372 | info->last_bb = current_bb; | |
2373 | info->first_set = cuid; | |
2374 | SET_BIT (reg_set_in_block[current_bb->index], regno); | |
2375 | } | |
2376 | } | |
2377 | ||
2378 | ||
2379 | /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn. | |
2380 | Note we store a pair of elements in the list, so they have to be | |
2381 | taken off pairwise. */ | |
2382 | ||
2383 | static void | |
2384 | canon_list_insert (dest, unused1, v_insn) | |
2385 | rtx dest ATTRIBUTE_UNUSED; | |
2386 | rtx unused1 ATTRIBUTE_UNUSED; | |
2387 | void * v_insn; | |
2388 | { | |
2389 | rtx dest_addr, insn; | |
2390 | int bb; | |
2391 | ||
2392 | while (GET_CODE (dest) == SUBREG | |
2393 | || GET_CODE (dest) == ZERO_EXTRACT | |
2394 | || GET_CODE (dest) == SIGN_EXTRACT | |
2395 | || GET_CODE (dest) == STRICT_LOW_PART) | |
2396 | dest = XEXP (dest, 0); | |
2397 | ||
2398 | /* If DEST is not a MEM, then it will not conflict with a load. Note | |
2399 | that function calls are assumed to clobber memory, but are handled | |
2400 | elsewhere. */ | |
2401 | ||
2402 | if (GET_CODE (dest) != MEM) | |
2403 | return; | |
2404 | ||
2405 | dest_addr = get_addr (XEXP (dest, 0)); | |
2406 | dest_addr = canon_rtx (dest_addr); | |
2407 | insn = (rtx) v_insn; | |
2408 | bb = BLOCK_NUM (insn); | |
2409 | ||
2410 | canon_modify_mem_list[bb] = | |
2411 | alloc_EXPR_LIST (VOIDmode, dest_addr, canon_modify_mem_list[bb]); | |
2412 | canon_modify_mem_list[bb] = | |
2413 | alloc_EXPR_LIST (VOIDmode, dest, canon_modify_mem_list[bb]); | |
2414 | bitmap_set_bit (canon_modify_mem_list_set, bb); | |
2415 | } | |
2416 | ||
2417 | /* Record memory modification information for INSN. We do not actually care | |
2418 | about the memory location(s) that are set, or even how they are set (consider | |
2419 | a CALL_INSN). We merely need to record which insns modify memory. */ | |
2420 | ||
2421 | static void | |
2422 | record_last_mem_set_info (insn) | |
2423 | rtx insn; | |
2424 | { | |
2425 | int bb = BLOCK_NUM (insn); | |
2426 | ||
2427 | /* load_killed_in_block_p will handle the case of calls clobbering | |
2428 | everything. */ | |
2429 | modify_mem_list[bb] = alloc_INSN_LIST (insn, modify_mem_list[bb]); | |
2430 | bitmap_set_bit (modify_mem_list_set, bb); | |
2431 | ||
2432 | if (GET_CODE (insn) == CALL_INSN) | |
2433 | { | |
2434 | /* Note that traversals of this loop (other than for free-ing) | |
2435 | will break after encountering a CALL_INSN. So, there's no | |
2436 | need to insert a pair of items, as canon_list_insert does. */ | |
2437 | canon_modify_mem_list[bb] = | |
2438 | alloc_INSN_LIST (insn, canon_modify_mem_list[bb]); | |
2439 | bitmap_set_bit (canon_modify_mem_list_set, bb); | |
2440 | } | |
2441 | else | |
2442 | note_stores (PATTERN (insn), canon_list_insert, (void*) insn); | |
2443 | } | |
2444 | ||
2445 | /* Called from compute_hash_table via note_stores to handle one | |
2446 | SET or CLOBBER in an insn. DATA is really the instruction in which | |
2447 | the SET is taking place. */ | |
2448 | ||
2449 | static void | |
2450 | record_last_set_info (dest, setter, data) | |
2451 | rtx dest, setter ATTRIBUTE_UNUSED; | |
2452 | void *data; | |
2453 | { | |
2454 | rtx last_set_insn = (rtx) data; | |
2455 | ||
2456 | if (GET_CODE (dest) == SUBREG) | |
2457 | dest = SUBREG_REG (dest); | |
2458 | ||
2459 | if (GET_CODE (dest) == REG) | |
2460 | record_last_reg_set_info (last_set_insn, REGNO (dest)); | |
2461 | else if (GET_CODE (dest) == MEM | |
2462 | /* Ignore pushes, they clobber nothing. */ | |
2463 | && ! push_operand (dest, GET_MODE (dest))) | |
2464 | record_last_mem_set_info (last_set_insn); | |
2465 | } | |
2466 | ||
2467 | /* Top level function to create an expression or assignment hash table. | |
2468 | ||
2469 | Expression entries are placed in the hash table if | |
2470 | - they are of the form (set (pseudo-reg) src), | |
2471 | - src is something we want to perform GCSE on, | |
2472 | - none of the operands are subsequently modified in the block | |
2473 | ||
2474 | Assignment entries are placed in the hash table if | |
2475 | - they are of the form (set (pseudo-reg) src), | |
2476 | - src is something we want to perform const/copy propagation on, | |
2477 | - none of the operands or target are subsequently modified in the block | |
2478 | ||
2479 | Currently src must be a pseudo-reg or a const_int. | |
2480 | ||
2481 | F is the first insn. | |
2482 | SET_P is non-zero for computing the assignment hash table. */ | |
2483 | ||
2484 | static void | |
2485 | compute_hash_table (set_p) | |
2486 | int set_p; | |
2487 | { | |
2488 | unsigned int i; | |
2489 | ||
2490 | /* While we compute the hash table we also compute a bit array of which | |
2491 | registers are set in which blocks. | |
2492 | ??? This isn't needed during const/copy propagation, but it's cheap to | |
2493 | compute. Later. */ | |
2494 | sbitmap_vector_zero (reg_set_in_block, last_basic_block); | |
2495 | ||
2496 | /* re-Cache any INSN_LIST nodes we have allocated. */ | |
2497 | clear_modify_mem_tables (); | |
2498 | /* Some working arrays used to track first and last set in each block. */ | |
2499 | reg_avail_info = (struct reg_avail_info*) | |
2500 | gmalloc (max_gcse_regno * sizeof (struct reg_avail_info)); | |
2501 | ||
2502 | for (i = 0; i < max_gcse_regno; ++i) | |
2503 | reg_avail_info[i].last_bb = NULL; | |
2504 | ||
2505 | FOR_EACH_BB (current_bb) | |
2506 | { | |
2507 | rtx insn; | |
2508 | unsigned int regno; | |
2509 | int in_libcall_block; | |
2510 | ||
2511 | /* First pass over the instructions records information used to | |
2512 | determine when registers and memory are first and last set. | |
2513 | ??? hard-reg reg_set_in_block computation | |
2514 | could be moved to compute_sets since they currently don't change. */ | |
2515 | ||
2516 | for (insn = current_bb->head; | |
2517 | insn && insn != NEXT_INSN (current_bb->end); | |
2518 | insn = NEXT_INSN (insn)) | |
2519 | { | |
2520 | if (! INSN_P (insn)) | |
2521 | continue; | |
2522 | ||
2523 | if (GET_CODE (insn) == CALL_INSN) | |
2524 | { | |
2525 | bool clobbers_all = false; | |
2526 | #ifdef NON_SAVING_SETJMP | |
2527 | if (NON_SAVING_SETJMP | |
2528 | && find_reg_note (insn, REG_SETJMP, NULL_RTX)) | |
2529 | clobbers_all = true; | |
2530 | #endif | |
2531 | ||
2532 | for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) | |
2533 | if (clobbers_all | |
2534 | || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno)) | |
2535 | record_last_reg_set_info (insn, regno); | |
2536 | ||
2537 | mark_call (insn); | |
2538 | } | |
2539 | ||
2540 | note_stores (PATTERN (insn), record_last_set_info, insn); | |
2541 | } | |
2542 | ||
2543 | /* The next pass builds the hash table. */ | |
2544 | ||
2545 | for (insn = current_bb->head, in_libcall_block = 0; | |
2546 | insn && insn != NEXT_INSN (current_bb->end); | |
2547 | insn = NEXT_INSN (insn)) | |
2548 | if (INSN_P (insn)) | |
2549 | { | |
2550 | if (find_reg_note (insn, REG_LIBCALL, NULL_RTX)) | |
2551 | in_libcall_block = 1; | |
2552 | else if (set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX)) | |
2553 | in_libcall_block = 0; | |
2554 | hash_scan_insn (insn, set_p, in_libcall_block); | |
2555 | if (!set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX)) | |
2556 | in_libcall_block = 0; | |
2557 | } | |
2558 | } | |
2559 | ||
2560 | free (reg_avail_info); | |
2561 | reg_avail_info = NULL; | |
2562 | } | |
2563 | ||
2564 | /* Allocate space for the set hash table. | |
2565 | N_INSNS is the number of instructions in the function. | |
2566 | It is used to determine the number of buckets to use. */ | |
2567 | ||
2568 | static void | |
2569 | alloc_set_hash_table (n_insns) | |
2570 | int n_insns; | |
2571 | { | |
2572 | int n; | |
2573 | ||
2574 | set_hash_table_size = n_insns / 4; | |
2575 | if (set_hash_table_size < 11) | |
2576 | set_hash_table_size = 11; | |
2577 | ||
2578 | /* Attempt to maintain efficient use of hash table. | |
2579 | Making it an odd number is simplest for now. | |
2580 | ??? Later take some measurements. */ | |
2581 | set_hash_table_size |= 1; | |
2582 | n = set_hash_table_size * sizeof (struct expr *); | |
2583 | set_hash_table = (struct expr **) gmalloc (n); | |
2584 | } | |
2585 | ||
2586 | /* Free things allocated by alloc_set_hash_table. */ | |
2587 | ||
2588 | static void | |
2589 | free_set_hash_table () | |
2590 | { | |
2591 | free (set_hash_table); | |
2592 | } | |
2593 | ||
2594 | /* Compute the hash table for doing copy/const propagation. */ | |
2595 | ||
2596 | static void | |
2597 | compute_set_hash_table () | |
2598 | { | |
2599 | /* Initialize count of number of entries in hash table. */ | |
2600 | n_sets = 0; | |
2601 | memset ((char *) set_hash_table, 0, | |
2602 | set_hash_table_size * sizeof (struct expr *)); | |
2603 | ||
2604 | compute_hash_table (1); | |
2605 | } | |
2606 | ||
2607 | /* Allocate space for the expression hash table. | |
2608 | N_INSNS is the number of instructions in the function. | |
2609 | It is used to determine the number of buckets to use. */ | |
2610 | ||
2611 | static void | |
2612 | alloc_expr_hash_table (n_insns) | |
2613 | unsigned int n_insns; | |
2614 | { | |
2615 | int n; | |
2616 | ||
2617 | expr_hash_table_size = n_insns / 2; | |
2618 | /* Make sure the amount is usable. */ | |
2619 | if (expr_hash_table_size < 11) | |
2620 | expr_hash_table_size = 11; | |
2621 | ||
2622 | /* Attempt to maintain efficient use of hash table. | |
2623 | Making it an odd number is simplest for now. | |
2624 | ??? Later take some measurements. */ | |
2625 | expr_hash_table_size |= 1; | |
2626 | n = expr_hash_table_size * sizeof (struct expr *); | |
2627 | expr_hash_table = (struct expr **) gmalloc (n); | |
2628 | } | |
2629 | ||
2630 | /* Free things allocated by alloc_expr_hash_table. */ | |
2631 | ||
2632 | static void | |
2633 | free_expr_hash_table () | |
2634 | { | |
2635 | free (expr_hash_table); | |
2636 | } | |
2637 | ||
2638 | /* Compute the hash table for doing GCSE. */ | |
2639 | ||
2640 | static void | |
2641 | compute_expr_hash_table () | |
2642 | { | |
2643 | /* Initialize count of number of entries in hash table. */ | |
2644 | n_exprs = 0; | |
2645 | memset ((char *) expr_hash_table, 0, | |
2646 | expr_hash_table_size * sizeof (struct expr *)); | |
2647 | ||
2648 | compute_hash_table (0); | |
2649 | } | |
2650 | \f | |
2651 | /* Expression tracking support. */ | |
2652 | ||
2653 | /* Lookup pattern PAT in the expression table. | |
2654 | The result is a pointer to the table entry, or NULL if not found. */ | |
2655 | ||
2656 | static struct expr * | |
2657 | lookup_expr (pat) | |
2658 | rtx pat; | |
2659 | { | |
2660 | int do_not_record_p; | |
2661 | unsigned int hash = hash_expr (pat, GET_MODE (pat), &do_not_record_p, | |
2662 | expr_hash_table_size); | |
2663 | struct expr *expr; | |
2664 | ||
2665 | if (do_not_record_p) | |
2666 | return NULL; | |
2667 | ||
2668 | expr = expr_hash_table[hash]; | |
2669 | ||
2670 | while (expr && ! expr_equiv_p (expr->expr, pat)) | |
2671 | expr = expr->next_same_hash; | |
2672 | ||
2673 | return expr; | |
2674 | } | |
2675 | ||
2676 | /* Lookup REGNO in the set table. If PAT is non-NULL look for the entry that | |
2677 | matches it, otherwise return the first entry for REGNO. The result is a | |
2678 | pointer to the table entry, or NULL if not found. */ | |
2679 | ||
2680 | static struct expr * | |
2681 | lookup_set (regno, pat) | |
2682 | unsigned int regno; | |
2683 | rtx pat; | |
2684 | { | |
2685 | unsigned int hash = hash_set (regno, set_hash_table_size); | |
2686 | struct expr *expr; | |
2687 | ||
2688 | expr = set_hash_table[hash]; | |
2689 | ||
2690 | if (pat) | |
2691 | { | |
2692 | while (expr && ! expr_equiv_p (expr->expr, pat)) | |
2693 | expr = expr->next_same_hash; | |
2694 | } | |
2695 | else | |
2696 | { | |
2697 | while (expr && REGNO (SET_DEST (expr->expr)) != regno) | |
2698 | expr = expr->next_same_hash; | |
2699 | } | |
2700 | ||
2701 | return expr; | |
2702 | } | |
2703 | ||
2704 | /* Return the next entry for REGNO in list EXPR. */ | |
2705 | ||
2706 | static struct expr * | |
2707 | next_set (regno, expr) | |
2708 | unsigned int regno; | |
2709 | struct expr *expr; | |
2710 | { | |
2711 | do | |
2712 | expr = expr->next_same_hash; | |
2713 | while (expr && REGNO (SET_DEST (expr->expr)) != regno); | |
2714 | ||
2715 | return expr; | |
2716 | } | |
2717 | ||
2718 | /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node | |
2719 | types may be mixed. */ | |
2720 | ||
2721 | static void | |
2722 | free_insn_expr_list_list (listp) | |
2723 | rtx *listp; | |
2724 | { | |
2725 | rtx list, next; | |
2726 | ||
2727 | for (list = *listp; list ; list = next) | |
2728 | { | |
2729 | next = XEXP (list, 1); | |
2730 | if (GET_CODE (list) == EXPR_LIST) | |
2731 | free_EXPR_LIST_node (list); | |
2732 | else | |
2733 | free_INSN_LIST_node (list); | |
2734 | } | |
2735 | ||
2736 | *listp = NULL; | |
2737 | } | |
2738 | ||
2739 | /* Clear canon_modify_mem_list and modify_mem_list tables. */ | |
2740 | static void | |
2741 | clear_modify_mem_tables () | |
2742 | { | |
2743 | int i; | |
2744 | ||
2745 | EXECUTE_IF_SET_IN_BITMAP | |
2746 | (modify_mem_list_set, 0, i, free_INSN_LIST_list (modify_mem_list + i)); | |
2747 | bitmap_clear (modify_mem_list_set); | |
2748 | ||
2749 | EXECUTE_IF_SET_IN_BITMAP | |
2750 | (canon_modify_mem_list_set, 0, i, | |
2751 | free_insn_expr_list_list (canon_modify_mem_list + i)); | |
2752 | bitmap_clear (canon_modify_mem_list_set); | |
2753 | } | |
2754 | ||
2755 | /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */ | |
2756 | ||
2757 | static void | |
2758 | free_modify_mem_tables () | |
2759 | { | |
2760 | clear_modify_mem_tables (); | |
2761 | free (modify_mem_list); | |
2762 | free (canon_modify_mem_list); | |
2763 | modify_mem_list = 0; | |
2764 | canon_modify_mem_list = 0; | |
2765 | } | |
2766 | ||
2767 | /* Reset tables used to keep track of what's still available [since the | |
2768 | start of the block]. */ | |
2769 | ||
2770 | static void | |
2771 | reset_opr_set_tables () | |
2772 | { | |
2773 | /* Maintain a bitmap of which regs have been set since beginning of | |
2774 | the block. */ | |
2775 | CLEAR_REG_SET (reg_set_bitmap); | |
2776 | ||
2777 | /* Also keep a record of the last instruction to modify memory. | |
2778 | For now this is very trivial, we only record whether any memory | |
2779 | location has been modified. */ | |
2780 | clear_modify_mem_tables (); | |
2781 | } | |
2782 | ||
2783 | /* Return non-zero if the operands of X are not set before INSN in | |
2784 | INSN's basic block. */ | |
2785 | ||
2786 | static int | |
2787 | oprs_not_set_p (x, insn) | |
2788 | rtx x, insn; | |
2789 | { | |
2790 | int i, j; | |
2791 | enum rtx_code code; | |
2792 | const char *fmt; | |
2793 | ||
2794 | if (x == 0) | |
2795 | return 1; | |
2796 | ||
2797 | code = GET_CODE (x); | |
2798 | switch (code) | |
2799 | { | |
2800 | case PC: | |
2801 | case CC0: | |
2802 | case CONST: | |
2803 | case CONST_INT: | |
2804 | case CONST_DOUBLE: | |
2805 | case CONST_VECTOR: | |
2806 | case SYMBOL_REF: | |
2807 | case LABEL_REF: | |
2808 | case ADDR_VEC: | |
2809 | case ADDR_DIFF_VEC: | |
2810 | return 1; | |
2811 | ||
2812 | case MEM: | |
2813 | if (load_killed_in_block_p (BLOCK_FOR_INSN (insn), | |
2814 | INSN_CUID (insn), x, 0)) | |
2815 | return 0; | |
2816 | else | |
2817 | return oprs_not_set_p (XEXP (x, 0), insn); | |
2818 | ||
2819 | case REG: | |
2820 | return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x)); | |
2821 | ||
2822 | default: | |
2823 | break; | |
2824 | } | |
2825 | ||
2826 | for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--) | |
2827 | { | |
2828 | if (fmt[i] == 'e') | |
2829 | { | |
2830 | /* If we are about to do the last recursive call | |
2831 | needed at this level, change it into iteration. | |
2832 | This function is called enough to be worth it. */ | |
2833 | if (i == 0) | |
2834 | return oprs_not_set_p (XEXP (x, i), insn); | |
2835 | ||
2836 | if (! oprs_not_set_p (XEXP (x, i), insn)) | |
2837 | return 0; | |
2838 | } | |
2839 | else if (fmt[i] == 'E') | |
2840 | for (j = 0; j < XVECLEN (x, i); j++) | |
2841 | if (! oprs_not_set_p (XVECEXP (x, i, j), insn)) | |
2842 | return 0; | |
2843 | } | |
2844 | ||
2845 | return 1; | |
2846 | } | |
2847 | ||
2848 | /* Mark things set by a CALL. */ | |
2849 | ||
2850 | static void | |
2851 | mark_call (insn) | |
2852 | rtx insn; | |
2853 | { | |
2854 | if (! CONST_OR_PURE_CALL_P (insn)) | |
2855 | record_last_mem_set_info (insn); | |
2856 | } | |
2857 | ||
2858 | /* Mark things set by a SET. */ | |
2859 | ||
2860 | static void | |
2861 | mark_set (pat, insn) | |
2862 | rtx pat, insn; | |
2863 | { | |
2864 | rtx dest = SET_DEST (pat); | |
2865 | ||
2866 | while (GET_CODE (dest) == SUBREG | |
2867 | || GET_CODE (dest) == ZERO_EXTRACT | |
2868 | || GET_CODE (dest) == SIGN_EXTRACT | |
2869 | || GET_CODE (dest) == STRICT_LOW_PART) | |
2870 | dest = XEXP (dest, 0); | |
2871 | ||
2872 | if (GET_CODE (dest) == REG) | |
2873 | SET_REGNO_REG_SET (reg_set_bitmap, REGNO (dest)); | |
2874 | else if (GET_CODE (dest) == MEM) | |
2875 | record_last_mem_set_info (insn); | |
2876 | ||
2877 | if (GET_CODE (SET_SRC (pat)) == CALL) | |
2878 | mark_call (insn); | |
2879 | } | |
2880 | ||
2881 | /* Record things set by a CLOBBER. */ | |
2882 | ||
2883 | static void | |
2884 | mark_clobber (pat, insn) | |
2885 | rtx pat, insn; | |
2886 | { | |
2887 | rtx clob = XEXP (pat, 0); | |
2888 | ||
2889 | while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART) | |
2890 | clob = XEXP (clob, 0); | |
2891 | ||
2892 | if (GET_CODE (clob) == REG) | |
2893 | SET_REGNO_REG_SET (reg_set_bitmap, REGNO (clob)); | |
2894 | else | |
2895 | record_last_mem_set_info (insn); | |
2896 | } | |
2897 | ||
2898 | /* Record things set by INSN. | |
2899 | This data is used by oprs_not_set_p. */ | |
2900 | ||
2901 | static void | |
2902 | mark_oprs_set (insn) | |
2903 | rtx insn; | |
2904 | { | |
2905 | rtx pat = PATTERN (insn); | |
2906 | int i; | |
2907 | ||
2908 | if (GET_CODE (pat) == SET) | |
2909 | mark_set (pat, insn); | |
2910 | else if (GET_CODE (pat) == PARALLEL) | |
2911 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
2912 | { | |
2913 | rtx x = XVECEXP (pat, 0, i); | |
2914 | ||
2915 | if (GET_CODE (x) == SET) | |
2916 | mark_set (x, insn); | |
2917 | else if (GET_CODE (x) == CLOBBER) | |
2918 | mark_clobber (x, insn); | |
2919 | else if (GET_CODE (x) == CALL) | |
2920 | mark_call (insn); | |
2921 | } | |
2922 | ||
2923 | else if (GET_CODE (pat) == CLOBBER) | |
2924 | mark_clobber (pat, insn); | |
2925 | else if (GET_CODE (pat) == CALL) | |
2926 | mark_call (insn); | |
2927 | } | |
2928 | ||
2929 | \f | |
2930 | /* Classic GCSE reaching definition support. */ | |
2931 | ||
2932 | /* Allocate reaching def variables. */ | |
2933 | ||
2934 | static void | |
2935 | alloc_rd_mem (n_blocks, n_insns) | |
2936 | int n_blocks, n_insns; | |
2937 | { | |
2938 | rd_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2939 | sbitmap_vector_zero (rd_kill, n_blocks); | |
2940 | ||
2941 | rd_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2942 | sbitmap_vector_zero (rd_gen, n_blocks); | |
2943 | ||
2944 | reaching_defs = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2945 | sbitmap_vector_zero (reaching_defs, n_blocks); | |
2946 | ||
2947 | rd_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2948 | sbitmap_vector_zero (rd_out, n_blocks); | |
2949 | } | |
2950 | ||
2951 | /* Free reaching def variables. */ | |
2952 | ||
2953 | static void | |
2954 | free_rd_mem () | |
2955 | { | |
2956 | sbitmap_vector_free (rd_kill); | |
2957 | sbitmap_vector_free (rd_gen); | |
2958 | sbitmap_vector_free (reaching_defs); | |
2959 | sbitmap_vector_free (rd_out); | |
2960 | } | |
2961 | ||
2962 | /* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */ | |
2963 | ||
2964 | static void | |
2965 | handle_rd_kill_set (insn, regno, bb) | |
2966 | rtx insn; | |
2967 | int regno; | |
2968 | basic_block bb; | |
2969 | { | |
2970 | struct reg_set *this_reg; | |
2971 | ||
2972 | for (this_reg = reg_set_table[regno]; this_reg; this_reg = this_reg ->next) | |
2973 | if (BLOCK_NUM (this_reg->insn) != BLOCK_NUM (insn)) | |
2974 | SET_BIT (rd_kill[bb->index], INSN_CUID (this_reg->insn)); | |
2975 | } | |
2976 | ||
2977 | /* Compute the set of kill's for reaching definitions. */ | |
2978 | ||
2979 | static void | |
2980 | compute_kill_rd () | |
2981 | { | |
2982 | int cuid; | |
2983 | unsigned int regno; | |
2984 | int i; | |
2985 | basic_block bb; | |
2986 | ||
2987 | /* For each block | |
2988 | For each set bit in `gen' of the block (i.e each insn which | |
2989 | generates a definition in the block) | |
2990 | Call the reg set by the insn corresponding to that bit regx | |
2991 | Look at the linked list starting at reg_set_table[regx] | |
2992 | For each setting of regx in the linked list, which is not in | |
2993 | this block | |
2994 | Set the bit in `kill' corresponding to that insn. */ | |
2995 | FOR_EACH_BB (bb) | |
2996 | for (cuid = 0; cuid < max_cuid; cuid++) | |
2997 | if (TEST_BIT (rd_gen[bb->index], cuid)) | |
2998 | { | |
2999 | rtx insn = CUID_INSN (cuid); | |
3000 | rtx pat = PATTERN (insn); | |
3001 | ||
3002 | if (GET_CODE (insn) == CALL_INSN) | |
3003 | { | |
3004 | for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) | |
3005 | if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno)) | |
3006 | handle_rd_kill_set (insn, regno, bb); | |
3007 | } | |
3008 | ||
3009 | if (GET_CODE (pat) == PARALLEL) | |
3010 | { | |
3011 | for (i = XVECLEN (pat, 0) - 1; i >= 0; i--) | |
3012 | { | |
3013 | enum rtx_code code = GET_CODE (XVECEXP (pat, 0, i)); | |
3014 | ||
3015 | if ((code == SET || code == CLOBBER) | |
3016 | && GET_CODE (XEXP (XVECEXP (pat, 0, i), 0)) == REG) | |
3017 | handle_rd_kill_set (insn, | |
3018 | REGNO (XEXP (XVECEXP (pat, 0, i), 0)), | |
3019 | bb); | |
3020 | } | |
3021 | } | |
3022 | else if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == REG) | |
3023 | /* Each setting of this register outside of this block | |
3024 | must be marked in the set of kills in this block. */ | |
3025 | handle_rd_kill_set (insn, REGNO (SET_DEST (pat)), bb); | |
3026 | } | |
3027 | } | |
3028 | ||
3029 | /* Compute the reaching definitions as in | |
3030 | Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman, | |
3031 | Chapter 10. It is the same algorithm as used for computing available | |
3032 | expressions but applied to the gens and kills of reaching definitions. */ | |
3033 | ||
3034 | static void | |
3035 | compute_rd () | |
3036 | { | |
3037 | int changed, passes; | |
3038 | basic_block bb; | |
3039 | ||
3040 | FOR_EACH_BB (bb) | |
3041 | sbitmap_copy (rd_out[bb->index] /*dst*/, rd_gen[bb->index] /*src*/); | |
3042 | ||
3043 | passes = 0; | |
3044 | changed = 1; | |
3045 | while (changed) | |
3046 | { | |
3047 | changed = 0; | |
3048 | FOR_EACH_BB (bb) | |
3049 | { | |
3050 | sbitmap_union_of_preds (reaching_defs[bb->index], rd_out, bb->index); | |
3051 | changed |= sbitmap_union_of_diff_cg (rd_out[bb->index], rd_gen[bb->index], | |
3052 | reaching_defs[bb->index], rd_kill[bb->index]); | |
3053 | } | |
3054 | passes++; | |
3055 | } | |
3056 | ||
3057 | if (gcse_file) | |
3058 | fprintf (gcse_file, "reaching def computation: %d passes\n", passes); | |
3059 | } | |
3060 | \f | |
3061 | /* Classic GCSE available expression support. */ | |
3062 | ||
3063 | /* Allocate memory for available expression computation. */ | |
3064 | ||
3065 | static void | |
3066 | alloc_avail_expr_mem (n_blocks, n_exprs) | |
3067 | int n_blocks, n_exprs; | |
3068 | { | |
3069 | ae_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
3070 | sbitmap_vector_zero (ae_kill, n_blocks); | |
3071 | ||
3072 | ae_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
3073 | sbitmap_vector_zero (ae_gen, n_blocks); | |
3074 | ||
3075 | ae_in = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
3076 | sbitmap_vector_zero (ae_in, n_blocks); | |
3077 | ||
3078 | ae_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
3079 | sbitmap_vector_zero (ae_out, n_blocks); | |
3080 | } | |
3081 | ||
3082 | static void | |
3083 | free_avail_expr_mem () | |
3084 | { | |
3085 | sbitmap_vector_free (ae_kill); | |
3086 | sbitmap_vector_free (ae_gen); | |
3087 | sbitmap_vector_free (ae_in); | |
3088 | sbitmap_vector_free (ae_out); | |
3089 | } | |
3090 | ||
3091 | /* Compute the set of available expressions generated in each basic block. */ | |
3092 | ||
3093 | static void | |
3094 | compute_ae_gen () | |
3095 | { | |
3096 | unsigned int i; | |
3097 | struct expr *expr; | |
3098 | struct occr *occr; | |
3099 | ||
3100 | /* For each recorded occurrence of each expression, set ae_gen[bb][expr]. | |
3101 | This is all we have to do because an expression is not recorded if it | |
3102 | is not available, and the only expressions we want to work with are the | |
3103 | ones that are recorded. */ | |
3104 | for (i = 0; i < expr_hash_table_size; i++) | |
3105 | for (expr = expr_hash_table[i]; expr != 0; expr = expr->next_same_hash) | |
3106 | for (occr = expr->avail_occr; occr != 0; occr = occr->next) | |
3107 | SET_BIT (ae_gen[BLOCK_NUM (occr->insn)], expr->bitmap_index); | |
3108 | } | |
3109 | ||
3110 | /* Return non-zero if expression X is killed in BB. */ | |
3111 | ||
3112 | static int | |
3113 | expr_killed_p (x, bb) | |
3114 | rtx x; | |
3115 | basic_block bb; | |
3116 | { | |
3117 | int i, j; | |
3118 | enum rtx_code code; | |
3119 | const char *fmt; | |
3120 | ||
3121 | if (x == 0) | |
3122 | return 1; | |
3123 | ||
3124 | code = GET_CODE (x); | |
3125 | switch (code) | |
3126 | { | |
3127 | case REG: | |
3128 | return TEST_BIT (reg_set_in_block[bb->index], REGNO (x)); | |
3129 | ||
3130 | case MEM: | |
3131 | if (load_killed_in_block_p (bb, get_max_uid () + 1, x, 0)) | |
3132 | return 1; | |
3133 | else | |
3134 | return expr_killed_p (XEXP (x, 0), bb); | |
3135 | ||
3136 | case PC: | |
3137 | case CC0: /*FIXME*/ | |
3138 | case CONST: | |
3139 | case CONST_INT: | |
3140 | case CONST_DOUBLE: | |
3141 | case CONST_VECTOR: | |
3142 | case SYMBOL_REF: | |
3143 | case LABEL_REF: | |
3144 | case ADDR_VEC: | |
3145 | case ADDR_DIFF_VEC: | |
3146 | return 0; | |
3147 | ||
3148 | default: | |
3149 | break; | |
3150 | } | |
3151 | ||
3152 | for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--) | |
3153 | { | |
3154 | if (fmt[i] == 'e') | |
3155 | { | |
3156 | /* If we are about to do the last recursive call | |
3157 | needed at this level, change it into iteration. | |
3158 | This function is called enough to be worth it. */ | |
3159 | if (i == 0) | |
3160 | return expr_killed_p (XEXP (x, i), bb); | |
3161 | else if (expr_killed_p (XEXP (x, i), bb)) | |
3162 | return 1; | |
3163 | } | |
3164 | else if (fmt[i] == 'E') | |
3165 | for (j = 0; j < XVECLEN (x, i); j++) | |
3166 | if (expr_killed_p (XVECEXP (x, i, j), bb)) | |
3167 | return 1; | |
3168 | } | |
3169 | ||
3170 | return 0; | |
3171 | } | |
3172 | ||
3173 | /* Compute the set of available expressions killed in each basic block. */ | |
3174 | ||
3175 | static void | |
3176 | compute_ae_kill (ae_gen, ae_kill) | |
3177 | sbitmap *ae_gen, *ae_kill; | |
3178 | { | |
3179 | basic_block bb; | |
3180 | unsigned int i; | |
3181 | struct expr *expr; | |
3182 | ||
3183 | FOR_EACH_BB (bb) | |
3184 | for (i = 0; i < expr_hash_table_size; i++) | |
3185 | for (expr = expr_hash_table[i]; expr; expr = expr->next_same_hash) | |
3186 | { | |
3187 | /* Skip EXPR if generated in this block. */ | |
3188 | if (TEST_BIT (ae_gen[bb->index], expr->bitmap_index)) | |
3189 | continue; | |
3190 | ||
3191 | if (expr_killed_p (expr->expr, bb)) | |
3192 | SET_BIT (ae_kill[bb->index], expr->bitmap_index); | |
3193 | } | |
3194 | } | |
3195 | \f | |
3196 | /* Actually perform the Classic GCSE optimizations. */ | |
3197 | ||
3198 | /* Return non-zero if occurrence OCCR of expression EXPR reaches block BB. | |
3199 | ||
3200 | CHECK_SELF_LOOP is non-zero if we should consider a block reaching itself | |
3201 | as a positive reach. We want to do this when there are two computations | |
3202 | of the expression in the block. | |
3203 | ||
3204 | VISITED is a pointer to a working buffer for tracking which BB's have | |
3205 | been visited. It is NULL for the top-level call. | |
3206 | ||
3207 | We treat reaching expressions that go through blocks containing the same | |
3208 | reaching expression as "not reaching". E.g. if EXPR is generated in blocks | |
3209 | 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block | |
3210 | 2 as not reaching. The intent is to improve the probability of finding | |
3211 | only one reaching expression and to reduce register lifetimes by picking | |
3212 | the closest such expression. */ | |
3213 | ||
3214 | static int | |
3215 | expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited) | |
3216 | struct occr *occr; | |
3217 | struct expr *expr; | |
3218 | basic_block bb; | |
3219 | int check_self_loop; | |
3220 | char *visited; | |
3221 | { | |
3222 | edge pred; | |
3223 | ||
3224 | for (pred = bb->pred; pred != NULL; pred = pred->pred_next) | |
3225 | { | |
3226 | basic_block pred_bb = pred->src; | |
3227 | ||
3228 | if (visited[pred_bb->index]) | |
3229 | /* This predecessor has already been visited. Nothing to do. */ | |
3230 | ; | |
3231 | else if (pred_bb == bb) | |
3232 | { | |
3233 | /* BB loops on itself. */ | |
3234 | if (check_self_loop | |
3235 | && TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index) | |
3236 | && BLOCK_NUM (occr->insn) == pred_bb->index) | |
3237 | return 1; | |
3238 | ||
3239 | visited[pred_bb->index] = 1; | |
3240 | } | |
3241 | ||
3242 | /* Ignore this predecessor if it kills the expression. */ | |
3243 | else if (TEST_BIT (ae_kill[pred_bb->index], expr->bitmap_index)) | |
3244 | visited[pred_bb->index] = 1; | |
3245 | ||
3246 | /* Does this predecessor generate this expression? */ | |
3247 | else if (TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index)) | |
3248 | { | |
3249 | /* Is this the occurrence we're looking for? | |
3250 | Note that there's only one generating occurrence per block | |
3251 | so we just need to check the block number. */ | |
3252 | if (BLOCK_NUM (occr->insn) == pred_bb->index) | |
3253 | return 1; | |
3254 | ||
3255 | visited[pred_bb->index] = 1; | |
3256 | } | |
3257 | ||
3258 | /* Neither gen nor kill. */ | |
3259 | else | |
3260 | { | |
3261 | visited[pred_bb->index] = 1; | |
3262 | if (expr_reaches_here_p_work (occr, expr, pred_bb, check_self_loop, | |
3263 | visited)) | |
3264 | ||
3265 | return 1; | |
3266 | } | |
3267 | } | |
3268 | ||
3269 | /* All paths have been checked. */ | |
3270 | return 0; | |
3271 | } | |
3272 | ||
3273 | /* This wrapper for expr_reaches_here_p_work() is to ensure that any | |
3274 | memory allocated for that function is returned. */ | |
3275 | ||
3276 | static int | |
3277 | expr_reaches_here_p (occr, expr, bb, check_self_loop) | |
3278 | struct occr *occr; | |
3279 | struct expr *expr; | |
3280 | basic_block bb; | |
3281 | int check_self_loop; | |
3282 | { | |
3283 | int rval; | |
3284 | char *visited = (char *) xcalloc (last_basic_block, 1); | |
3285 | ||
3286 | rval = expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited); | |
3287 | ||
3288 | free (visited); | |
3289 | return rval; | |
3290 | } | |
3291 | ||
3292 | /* Return the instruction that computes EXPR that reaches INSN's basic block. | |
3293 | If there is more than one such instruction, return NULL. | |
3294 | ||
3295 | Called only by handle_avail_expr. */ | |
3296 | ||
3297 | static rtx | |
3298 | computing_insn (expr, insn) | |
3299 | struct expr *expr; | |
3300 | rtx insn; | |
3301 | { | |
3302 | basic_block bb = BLOCK_FOR_INSN (insn); | |
3303 | ||
3304 | if (expr->avail_occr->next == NULL) | |
3305 | { | |
3306 | if (BLOCK_FOR_INSN (expr->avail_occr->insn) == bb) | |
3307 | /* The available expression is actually itself | |
3308 | (i.e. a loop in the flow graph) so do nothing. */ | |
3309 | return NULL; | |
3310 | ||
3311 | /* (FIXME) Case that we found a pattern that was created by | |
3312 | a substitution that took place. */ | |
3313 | return expr->avail_occr->insn; | |
3314 | } | |
3315 | else | |
3316 | { | |
3317 | /* Pattern is computed more than once. | |
3318 | Search backwards from this insn to see how many of these | |
3319 | computations actually reach this insn. */ | |
3320 | struct occr *occr; | |
3321 | rtx insn_computes_expr = NULL; | |
3322 | int can_reach = 0; | |
3323 | ||
3324 | for (occr = expr->avail_occr; occr != NULL; occr = occr->next) | |
3325 | { | |
3326 | if (BLOCK_FOR_INSN (occr->insn) == bb) | |
3327 | { | |
3328 | /* The expression is generated in this block. | |
3329 | The only time we care about this is when the expression | |
3330 | is generated later in the block [and thus there's a loop]. | |
3331 | We let the normal cse pass handle the other cases. */ | |
3332 | if (INSN_CUID (insn) < INSN_CUID (occr->insn) | |
3333 | && expr_reaches_here_p (occr, expr, bb, 1)) | |
3334 | { | |
3335 | can_reach++; | |
3336 | if (can_reach > 1) | |
3337 | return NULL; | |
3338 | ||
3339 | insn_computes_expr = occr->insn; | |
3340 | } | |
3341 | } | |
3342 | else if (expr_reaches_here_p (occr, expr, bb, 0)) | |
3343 | { | |
3344 | can_reach++; | |
3345 | if (can_reach > 1) | |
3346 | return NULL; | |
3347 | ||
3348 | insn_computes_expr = occr->insn; | |
3349 | } | |
3350 | } | |
3351 | ||
3352 | if (insn_computes_expr == NULL) | |
3353 | abort (); | |
3354 | ||
3355 | return insn_computes_expr; | |
3356 | } | |
3357 | } | |
3358 | ||
3359 | /* Return non-zero if the definition in DEF_INSN can reach INSN. | |
3360 | Only called by can_disregard_other_sets. */ | |
3361 | ||
3362 | static int | |
3363 | def_reaches_here_p (insn, def_insn) | |
3364 | rtx insn, def_insn; | |
3365 | { | |
3366 | rtx reg; | |
3367 | ||
3368 | if (TEST_BIT (reaching_defs[BLOCK_NUM (insn)], INSN_CUID (def_insn))) | |
3369 | return 1; | |
3370 | ||
3371 | if (BLOCK_NUM (insn) == BLOCK_NUM (def_insn)) | |
3372 | { | |
3373 | if (INSN_CUID (def_insn) < INSN_CUID (insn)) | |
3374 | { | |
3375 | if (GET_CODE (PATTERN (def_insn)) == PARALLEL) | |
3376 | return 1; | |
3377 | else if (GET_CODE (PATTERN (def_insn)) == CLOBBER) | |
3378 | reg = XEXP (PATTERN (def_insn), 0); | |
3379 | else if (GET_CODE (PATTERN (def_insn)) == SET) | |
3380 | reg = SET_DEST (PATTERN (def_insn)); | |
3381 | else | |
3382 | abort (); | |
3383 | ||
3384 | return ! reg_set_between_p (reg, NEXT_INSN (def_insn), insn); | |
3385 | } | |
3386 | else | |
3387 | return 0; | |
3388 | } | |
3389 | ||
3390 | return 0; | |
3391 | } | |
3392 | ||
3393 | /* Return non-zero if *ADDR_THIS_REG can only have one value at INSN. The | |
3394 | value returned is the number of definitions that reach INSN. Returning a | |
3395 | value of zero means that [maybe] more than one definition reaches INSN and | |
3396 | the caller can't perform whatever optimization it is trying. i.e. it is | |
3397 | always safe to return zero. */ | |
3398 | ||
3399 | static int | |
3400 | can_disregard_other_sets (addr_this_reg, insn, for_combine) | |
3401 | struct reg_set **addr_this_reg; | |
3402 | rtx insn; | |
3403 | int for_combine; | |
3404 | { | |
3405 | int number_of_reaching_defs = 0; | |
3406 | struct reg_set *this_reg; | |
3407 | ||
3408 | for (this_reg = *addr_this_reg; this_reg != 0; this_reg = this_reg->next) | |
3409 | if (def_reaches_here_p (insn, this_reg->insn)) | |
3410 | { | |
3411 | number_of_reaching_defs++; | |
3412 | /* Ignore parallels for now. */ | |
3413 | if (GET_CODE (PATTERN (this_reg->insn)) == PARALLEL) | |
3414 | return 0; | |
3415 | ||
3416 | if (!for_combine | |
3417 | && (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER | |
3418 | || ! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)), | |
3419 | SET_SRC (PATTERN (insn))))) | |
3420 | /* A setting of the reg to a different value reaches INSN. */ | |
3421 | return 0; | |
3422 | ||
3423 | if (number_of_reaching_defs > 1) | |
3424 | { | |
3425 | /* If in this setting the value the register is being set to is | |
3426 | equal to the previous value the register was set to and this | |
3427 | setting reaches the insn we are trying to do the substitution | |
3428 | on then we are ok. */ | |
3429 | if (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER) | |
3430 | return 0; | |
3431 | else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)), | |
3432 | SET_SRC (PATTERN (insn)))) | |
3433 | return 0; | |
3434 | } | |
3435 | ||
3436 | *addr_this_reg = this_reg; | |
3437 | } | |
3438 | ||
3439 | return number_of_reaching_defs; | |
3440 | } | |
3441 | ||
3442 | /* Expression computed by insn is available and the substitution is legal, | |
3443 | so try to perform the substitution. | |
3444 | ||
3445 | The result is non-zero if any changes were made. */ | |
3446 | ||
3447 | static int | |
3448 | handle_avail_expr (insn, expr) | |
3449 | rtx insn; | |
3450 | struct expr *expr; | |
3451 | { | |
3452 | rtx pat, insn_computes_expr, expr_set; | |
3453 | rtx to; | |
3454 | struct reg_set *this_reg; | |
3455 | int found_setting, use_src; | |
3456 | int changed = 0; | |
3457 | ||
3458 | /* We only handle the case where one computation of the expression | |
3459 | reaches this instruction. */ | |
3460 | insn_computes_expr = computing_insn (expr, insn); | |
3461 | if (insn_computes_expr == NULL) | |
3462 | return 0; | |
3463 | expr_set = single_set (insn_computes_expr); | |
3464 | if (!expr_set) | |
3465 | abort (); | |
3466 | ||
3467 | found_setting = 0; | |
3468 | use_src = 0; | |
3469 | ||
3470 | /* At this point we know only one computation of EXPR outside of this | |
3471 | block reaches this insn. Now try to find a register that the | |
3472 | expression is computed into. */ | |
3473 | if (GET_CODE (SET_SRC (expr_set)) == REG) | |
3474 | { | |
3475 | /* This is the case when the available expression that reaches | |
3476 | here has already been handled as an available expression. */ | |
3477 | unsigned int regnum_for_replacing | |
3478 | = REGNO (SET_SRC (expr_set)); | |
3479 | ||
3480 | /* If the register was created by GCSE we can't use `reg_set_table', | |
3481 | however we know it's set only once. */ | |
3482 | if (regnum_for_replacing >= max_gcse_regno | |
3483 | /* If the register the expression is computed into is set only once, | |
3484 | or only one set reaches this insn, we can use it. */ | |
3485 | || (((this_reg = reg_set_table[regnum_for_replacing]), | |
3486 | this_reg->next == NULL) | |
3487 | || can_disregard_other_sets (&this_reg, insn, 0))) | |
3488 | { | |
3489 | use_src = 1; | |
3490 | found_setting = 1; | |
3491 | } | |
3492 | } | |
3493 | ||
3494 | if (!found_setting) | |
3495 | { | |
3496 | unsigned int regnum_for_replacing | |
3497 | = REGNO (SET_DEST (expr_set)); | |
3498 | ||
3499 | /* This shouldn't happen. */ | |
3500 | if (regnum_for_replacing >= max_gcse_regno) | |
3501 | abort (); | |
3502 | ||
3503 | this_reg = reg_set_table[regnum_for_replacing]; | |
3504 | ||
3505 | /* If the register the expression is computed into is set only once, | |
3506 | or only one set reaches this insn, use it. */ | |
3507 | if (this_reg->next == NULL | |
3508 | || can_disregard_other_sets (&this_reg, insn, 0)) | |
3509 | found_setting = 1; | |
3510 | } | |
3511 | ||
3512 | if (found_setting) | |
3513 | { | |
3514 | pat = PATTERN (insn); | |
3515 | if (use_src) | |
3516 | to = SET_SRC (expr_set); | |
3517 | else | |
3518 | to = SET_DEST (expr_set); | |
3519 | changed = validate_change (insn, &SET_SRC (pat), to, 0); | |
3520 | ||
3521 | /* We should be able to ignore the return code from validate_change but | |
3522 | to play it safe we check. */ | |
3523 | if (changed) | |
3524 | { | |
3525 | gcse_subst_count++; | |
3526 | if (gcse_file != NULL) | |
3527 | { | |
3528 | fprintf (gcse_file, "GCSE: Replacing the source in insn %d with", | |
3529 | INSN_UID (insn)); | |
3530 | fprintf (gcse_file, " reg %d %s insn %d\n", | |
3531 | REGNO (to), use_src ? "from" : "set in", | |
3532 | INSN_UID (insn_computes_expr)); | |
3533 | } | |
3534 | } | |
3535 | } | |
3536 | ||
3537 | /* The register that the expr is computed into is set more than once. */ | |
3538 | else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/) | |
3539 | { | |
3540 | /* Insert an insn after insnx that copies the reg set in insnx | |
3541 | into a new pseudo register call this new register REGN. | |
3542 | From insnb until end of basic block or until REGB is set | |
3543 | replace all uses of REGB with REGN. */ | |
3544 | rtx new_insn; | |
3545 | ||
3546 | to = gen_reg_rtx (GET_MODE (SET_DEST (expr_set))); | |
3547 | ||
3548 | /* Generate the new insn. */ | |
3549 | /* ??? If the change fails, we return 0, even though we created | |
3550 | an insn. I think this is ok. */ | |
3551 | new_insn | |
3552 | = emit_insn_after (gen_rtx_SET (VOIDmode, to, | |
3553 | SET_DEST (expr_set)), | |
3554 | insn_computes_expr); | |
3555 | ||
3556 | /* Keep register set table up to date. */ | |
3557 | record_one_set (REGNO (to), new_insn); | |
3558 | ||
3559 | gcse_create_count++; | |
3560 | if (gcse_file != NULL) | |
3561 | { | |
3562 | fprintf (gcse_file, "GCSE: Creating insn %d to copy value of reg %d", | |
3563 | INSN_UID (NEXT_INSN (insn_computes_expr)), | |
3564 | REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr))))); | |
3565 | fprintf (gcse_file, ", computed in insn %d,\n", | |
3566 | INSN_UID (insn_computes_expr)); | |
3567 | fprintf (gcse_file, " into newly allocated reg %d\n", | |
3568 | REGNO (to)); | |
3569 | } | |
3570 | ||
3571 | pat = PATTERN (insn); | |
3572 | ||
3573 | /* Do register replacement for INSN. */ | |
3574 | changed = validate_change (insn, &SET_SRC (pat), | |
3575 | SET_DEST (PATTERN | |
3576 | (NEXT_INSN (insn_computes_expr))), | |
3577 | 0); | |
3578 | ||
3579 | /* We should be able to ignore the return code from validate_change but | |
3580 | to play it safe we check. */ | |
3581 | if (changed) | |
3582 | { | |
3583 | gcse_subst_count++; | |
3584 | if (gcse_file != NULL) | |
3585 | { | |
3586 | fprintf (gcse_file, | |
3587 | "GCSE: Replacing the source in insn %d with reg %d ", | |
3588 | INSN_UID (insn), | |
3589 | REGNO (SET_DEST (PATTERN (NEXT_INSN | |
3590 | (insn_computes_expr))))); | |
3591 | fprintf (gcse_file, "set in insn %d\n", | |
3592 | INSN_UID (insn_computes_expr)); | |
3593 | } | |
3594 | } | |
3595 | } | |
3596 | ||
3597 | return changed; | |
3598 | } | |
3599 | ||
3600 | /* Perform classic GCSE. This is called by one_classic_gcse_pass after all | |
3601 | the dataflow analysis has been done. | |
3602 | ||
3603 | The result is non-zero if a change was made. */ | |
3604 | ||
3605 | static int | |
3606 | classic_gcse () | |
3607 | { | |
3608 | int changed; | |
3609 | rtx insn; | |
3610 | basic_block bb; | |
3611 | ||
3612 | /* Note we start at block 1. */ | |
3613 | ||
3614 | if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR) | |
3615 | return 0; | |
3616 | ||
3617 | changed = 0; | |
3618 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb) | |
3619 | { | |
3620 | /* Reset tables used to keep track of what's still valid [since the | |
3621 | start of the block]. */ | |
3622 | reset_opr_set_tables (); | |
3623 | ||
3624 | for (insn = bb->head; | |
3625 | insn != NULL && insn != NEXT_INSN (bb->end); | |
3626 | insn = NEXT_INSN (insn)) | |
3627 | { | |
3628 | /* Is insn of form (set (pseudo-reg) ...)? */ | |
3629 | if (GET_CODE (insn) == INSN | |
3630 | && GET_CODE (PATTERN (insn)) == SET | |
3631 | && GET_CODE (SET_DEST (PATTERN (insn))) == REG | |
3632 | && REGNO (SET_DEST (PATTERN (insn))) >= FIRST_PSEUDO_REGISTER) | |
3633 | { | |
3634 | rtx pat = PATTERN (insn); | |
3635 | rtx src = SET_SRC (pat); | |
3636 | struct expr *expr; | |
3637 | ||
3638 | if (want_to_gcse_p (src) | |
3639 | /* Is the expression recorded? */ | |
3640 | && ((expr = lookup_expr (src)) != NULL) | |
3641 | /* Is the expression available [at the start of the | |
3642 | block]? */ | |
3643 | && TEST_BIT (ae_in[bb->index], expr->bitmap_index) | |
3644 | /* Are the operands unchanged since the start of the | |
3645 | block? */ | |
3646 | && oprs_not_set_p (src, insn)) | |
3647 | changed |= handle_avail_expr (insn, expr); | |
3648 | } | |
3649 | ||
3650 | /* Keep track of everything modified by this insn. */ | |
3651 | /* ??? Need to be careful w.r.t. mods done to INSN. */ | |
3652 | if (INSN_P (insn)) | |
3653 | mark_oprs_set (insn); | |
3654 | } | |
3655 | } | |
3656 | ||
3657 | return changed; | |
3658 | } | |
3659 | ||
3660 | /* Top level routine to perform one classic GCSE pass. | |
3661 | ||
3662 | Return non-zero if a change was made. */ | |
3663 | ||
3664 | static int | |
3665 | one_classic_gcse_pass (pass) | |
3666 | int pass; | |
3667 | { | |
3668 | int changed = 0; | |
3669 | ||
3670 | gcse_subst_count = 0; | |
3671 | gcse_create_count = 0; | |
3672 | ||
3673 | alloc_expr_hash_table (max_cuid); | |
3674 | alloc_rd_mem (last_basic_block, max_cuid); | |
3675 | compute_expr_hash_table (); | |
3676 | if (gcse_file) | |
3677 | dump_hash_table (gcse_file, "Expression", expr_hash_table, | |
3678 | expr_hash_table_size, n_exprs); | |
3679 | ||
3680 | if (n_exprs > 0) | |
3681 | { | |
3682 | compute_kill_rd (); | |
3683 | compute_rd (); | |
3684 | alloc_avail_expr_mem (last_basic_block, n_exprs); | |
3685 | compute_ae_gen (); | |
3686 | compute_ae_kill (ae_gen, ae_kill); | |
3687 | compute_available (ae_gen, ae_kill, ae_out, ae_in); | |
3688 | changed = classic_gcse (); | |
3689 | free_avail_expr_mem (); | |
3690 | } | |
3691 | ||
3692 | free_rd_mem (); | |
3693 | free_expr_hash_table (); | |
3694 | ||
3695 | if (gcse_file) | |
3696 | { | |
3697 | fprintf (gcse_file, "\n"); | |
3698 | fprintf (gcse_file, "GCSE of %s, pass %d: %d bytes needed, %d substs,", | |
3699 | current_function_name, pass, bytes_used, gcse_subst_count); | |
3700 | fprintf (gcse_file, "%d insns created\n", gcse_create_count); | |
3701 | } | |
3702 | ||
3703 | return changed; | |
3704 | } | |
3705 | \f | |
3706 | /* Compute copy/constant propagation working variables. */ | |
3707 | ||
3708 | /* Local properties of assignments. */ | |
3709 | static sbitmap *cprop_pavloc; | |
3710 | static sbitmap *cprop_absaltered; | |
3711 | ||
3712 | /* Global properties of assignments (computed from the local properties). */ | |
3713 | static sbitmap *cprop_avin; | |
3714 | static sbitmap *cprop_avout; | |
3715 | ||
3716 | /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of | |
3717 | basic blocks. N_SETS is the number of sets. */ | |
3718 | ||
3719 | static void | |
3720 | alloc_cprop_mem (n_blocks, n_sets) | |
3721 | int n_blocks, n_sets; | |
3722 | { | |
3723 | cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets); | |
3724 | cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets); | |
3725 | ||
3726 | cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets); | |
3727 | cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets); | |
3728 | } | |
3729 | ||
3730 | /* Free vars used by copy/const propagation. */ | |
3731 | ||
3732 | static void | |
3733 | free_cprop_mem () | |
3734 | { | |
3735 | sbitmap_vector_free (cprop_pavloc); | |
3736 | sbitmap_vector_free (cprop_absaltered); | |
3737 | sbitmap_vector_free (cprop_avin); | |
3738 | sbitmap_vector_free (cprop_avout); | |
3739 | } | |
3740 | ||
3741 | /* For each block, compute whether X is transparent. X is either an | |
3742 | expression or an assignment [though we don't care which, for this context | |
3743 | an assignment is treated as an expression]. For each block where an | |
3744 | element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX | |
3745 | bit in BMAP. */ | |
3746 | ||
3747 | static void | |
3748 | compute_transp (x, indx, bmap, set_p) | |
3749 | rtx x; | |
3750 | int indx; | |
3751 | sbitmap *bmap; | |
3752 | int set_p; | |
3753 | { | |
3754 | int i, j; | |
3755 | basic_block bb; | |
3756 | enum rtx_code code; | |
3757 | reg_set *r; | |
3758 | const char *fmt; | |
3759 | ||
3760 | /* repeat is used to turn tail-recursion into iteration since GCC | |
3761 | can't do it when there's no return value. */ | |
3762 | repeat: | |
3763 | ||
3764 | if (x == 0) | |
3765 | return; | |
3766 | ||
3767 | code = GET_CODE (x); | |
3768 | switch (code) | |
3769 | { | |
3770 | case REG: | |
3771 | if (set_p) | |
3772 | { | |
3773 | if (REGNO (x) < FIRST_PSEUDO_REGISTER) | |
3774 | { | |
3775 | FOR_EACH_BB (bb) | |
3776 | if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x))) | |
3777 | SET_BIT (bmap[bb->index], indx); | |
3778 | } | |
3779 | else | |
3780 | { | |
3781 | for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next) | |
3782 | SET_BIT (bmap[BLOCK_NUM (r->insn)], indx); | |
3783 | } | |
3784 | } | |
3785 | else | |
3786 | { | |
3787 | if (REGNO (x) < FIRST_PSEUDO_REGISTER) | |
3788 | { | |
3789 | FOR_EACH_BB (bb) | |
3790 | if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x))) | |
3791 | RESET_BIT (bmap[bb->index], indx); | |
3792 | } | |
3793 | else | |
3794 | { | |
3795 | for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next) | |
3796 | RESET_BIT (bmap[BLOCK_NUM (r->insn)], indx); | |
3797 | } | |
3798 | } | |
3799 | ||
3800 | return; | |
3801 | ||
3802 | case MEM: | |
3803 | FOR_EACH_BB (bb) | |
3804 | { | |
3805 | rtx list_entry = canon_modify_mem_list[bb->index]; | |
3806 | ||
3807 | while (list_entry) | |
3808 | { | |
3809 | rtx dest, dest_addr; | |
3810 | ||
3811 | if (GET_CODE (XEXP (list_entry, 0)) == CALL_INSN) | |
3812 | { | |
3813 | if (set_p) | |
3814 | SET_BIT (bmap[bb->index], indx); | |
3815 | else | |
3816 | RESET_BIT (bmap[bb->index], indx); | |
3817 | break; | |
3818 | } | |
3819 | /* LIST_ENTRY must be an INSN of some kind that sets memory. | |
3820 | Examine each hunk of memory that is modified. */ | |
3821 | ||
3822 | dest = XEXP (list_entry, 0); | |
3823 | list_entry = XEXP (list_entry, 1); | |
3824 | dest_addr = XEXP (list_entry, 0); | |
3825 | ||
3826 | if (canon_true_dependence (dest, GET_MODE (dest), dest_addr, | |
3827 | x, rtx_addr_varies_p)) | |
3828 | { | |
3829 | if (set_p) | |
3830 | SET_BIT (bmap[bb->index], indx); | |
3831 | else | |
3832 | RESET_BIT (bmap[bb->index], indx); | |
3833 | break; | |
3834 | } | |
3835 | list_entry = XEXP (list_entry, 1); | |
3836 | } | |
3837 | } | |
3838 | ||
3839 | x = XEXP (x, 0); | |
3840 | goto repeat; | |
3841 | ||
3842 | case PC: | |
3843 | case CC0: /*FIXME*/ | |
3844 | case CONST: | |
3845 | case CONST_INT: | |
3846 | case CONST_DOUBLE: | |
3847 | case CONST_VECTOR: | |
3848 | case SYMBOL_REF: | |
3849 | case LABEL_REF: | |
3850 | case ADDR_VEC: | |
3851 | case ADDR_DIFF_VEC: | |
3852 | return; | |
3853 | ||
3854 | default: | |
3855 | break; | |
3856 | } | |
3857 | ||
3858 | for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--) | |
3859 | { | |
3860 | if (fmt[i] == 'e') | |
3861 | { | |
3862 | /* If we are about to do the last recursive call | |
3863 | needed at this level, change it into iteration. | |
3864 | This function is called enough to be worth it. */ | |
3865 | if (i == 0) | |
3866 | { | |
3867 | x = XEXP (x, i); | |
3868 | goto repeat; | |
3869 | } | |
3870 | ||
3871 | compute_transp (XEXP (x, i), indx, bmap, set_p); | |
3872 | } | |
3873 | else if (fmt[i] == 'E') | |
3874 | for (j = 0; j < XVECLEN (x, i); j++) | |
3875 | compute_transp (XVECEXP (x, i, j), indx, bmap, set_p); | |
3876 | } | |
3877 | } | |
3878 | ||
3879 | /* Top level routine to do the dataflow analysis needed by copy/const | |
3880 | propagation. */ | |
3881 | ||
3882 | static void | |
3883 | compute_cprop_data () | |
3884 | { | |
3885 | compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, 1); | |
3886 | compute_available (cprop_pavloc, cprop_absaltered, | |
3887 | cprop_avout, cprop_avin); | |
3888 | } | |
3889 | \f | |
3890 | /* Copy/constant propagation. */ | |
3891 | ||
3892 | /* Maximum number of register uses in an insn that we handle. */ | |
3893 | #define MAX_USES 8 | |
3894 | ||
3895 | /* Table of uses found in an insn. | |
3896 | Allocated statically to avoid alloc/free complexity and overhead. */ | |
3897 | static struct reg_use reg_use_table[MAX_USES]; | |
3898 | ||
3899 | /* Index into `reg_use_table' while building it. */ | |
3900 | static int reg_use_count; | |
3901 | ||
3902 | /* Set up a list of register numbers used in INSN. The found uses are stored | |
3903 | in `reg_use_table'. `reg_use_count' is initialized to zero before entry, | |
3904 | and contains the number of uses in the table upon exit. | |
3905 | ||
3906 | ??? If a register appears multiple times we will record it multiple times. | |
3907 | This doesn't hurt anything but it will slow things down. */ | |
3908 | ||
3909 | static void | |
3910 | find_used_regs (xptr, data) | |
3911 | rtx *xptr; | |
3912 | void *data ATTRIBUTE_UNUSED; | |
3913 | { | |
3914 | int i, j; | |
3915 | enum rtx_code code; | |
3916 | const char *fmt; | |
3917 | rtx x = *xptr; | |
3918 | ||
3919 | /* repeat is used to turn tail-recursion into iteration since GCC | |
3920 | can't do it when there's no return value. */ | |
3921 | repeat: | |
3922 | if (x == 0) | |
3923 | return; | |
3924 | ||
3925 | code = GET_CODE (x); | |
3926 | if (REG_P (x)) | |
3927 | { | |
3928 | if (reg_use_count == MAX_USES) | |
3929 | return; | |
3930 | ||
3931 | reg_use_table[reg_use_count].reg_rtx = x; | |
3932 | reg_use_count++; | |
3933 | } | |
3934 | ||
3935 | /* Recursively scan the operands of this expression. */ | |
3936 | ||
3937 | for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--) | |
3938 | { | |
3939 | if (fmt[i] == 'e') | |
3940 | { | |
3941 | /* If we are about to do the last recursive call | |
3942 | needed at this level, change it into iteration. | |
3943 | This function is called enough to be worth it. */ | |
3944 | if (i == 0) | |
3945 | { | |
3946 | x = XEXP (x, 0); | |
3947 | goto repeat; | |
3948 | } | |
3949 | ||
3950 | find_used_regs (&XEXP (x, i), data); | |
3951 | } | |
3952 | else if (fmt[i] == 'E') | |
3953 | for (j = 0; j < XVECLEN (x, i); j++) | |
3954 | find_used_regs (&XVECEXP (x, i, j), data); | |
3955 | } | |
3956 | } | |
3957 | ||
3958 | /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO. | |
3959 | Returns non-zero is successful. */ | |
3960 | ||
3961 | static int | |
3962 | try_replace_reg (from, to, insn) | |
3963 | rtx from, to, insn; | |
3964 | { | |
3965 | rtx note = find_reg_equal_equiv_note (insn); | |
3966 | rtx src = 0; | |
3967 | int success = 0; | |
3968 | rtx set = single_set (insn); | |
3969 | ||
3970 | validate_replace_src_group (from, to, insn); | |
3971 | if (num_changes_pending () && apply_change_group ()) | |
3972 | success = 1; | |
3973 | ||
3974 | if (!success && set && reg_mentioned_p (from, SET_SRC (set))) | |
3975 | { | |
3976 | /* If above failed and this is a single set, try to simplify the source of | |
3977 | the set given our substitution. We could perhaps try this for multiple | |
3978 | SETs, but it probably won't buy us anything. */ | |
3979 | src = simplify_replace_rtx (SET_SRC (set), from, to); | |
3980 | ||
3981 | if (!rtx_equal_p (src, SET_SRC (set)) | |
3982 | && validate_change (insn, &SET_SRC (set), src, 0)) | |
3983 | success = 1; | |
3984 | ||
3985 | /* If we've failed to do replacement, have a single SET, and don't already | |
3986 | have a note, add a REG_EQUAL note to not lose information. */ | |
3987 | if (!success && note == 0 && set != 0) | |
3988 | note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src)); | |
3989 | } | |
3990 | ||
3991 | /* If there is already a NOTE, update the expression in it with our | |
3992 | replacement. */ | |
3993 | else if (note != 0) | |
3994 | XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), from, to); | |
3995 | ||
3996 | /* REG_EQUAL may get simplified into register. | |
3997 | We don't allow that. Remove that note. This code ought | |
3998 | not to hapen, because previous code ought to syntetize | |
3999 | reg-reg move, but be on the safe side. */ | |
4000 | if (note && REG_P (XEXP (note, 0))) | |
4001 | remove_note (insn, note); | |
4002 | ||
4003 | return success; | |
4004 | } | |
4005 | ||
4006 | /* Find a set of REGNOs that are available on entry to INSN's block. Returns | |
4007 | NULL no such set is found. */ | |
4008 | ||
4009 | static struct expr * | |
4010 | find_avail_set (regno, insn) | |
4011 | int regno; | |
4012 | rtx insn; | |
4013 | { | |
4014 | /* SET1 contains the last set found that can be returned to the caller for | |
4015 | use in a substitution. */ | |
4016 | struct expr *set1 = 0; | |
4017 | ||
4018 | /* Loops are not possible here. To get a loop we would need two sets | |
4019 | available at the start of the block containing INSN. ie we would | |
4020 | need two sets like this available at the start of the block: | |
4021 | ||
4022 | (set (reg X) (reg Y)) | |
4023 | (set (reg Y) (reg X)) | |
4024 | ||
4025 | This can not happen since the set of (reg Y) would have killed the | |
4026 | set of (reg X) making it unavailable at the start of this block. */ | |
4027 | while (1) | |
4028 | { | |
4029 | rtx src; | |
4030 | struct expr *set = lookup_set (regno, NULL_RTX); | |
4031 | ||
4032 | /* Find a set that is available at the start of the block | |
4033 | which contains INSN. */ | |
4034 | while (set) | |
4035 | { | |
4036 | if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index)) | |
4037 | break; | |
4038 | set = next_set (regno, set); | |
4039 | } | |
4040 | ||
4041 | /* If no available set was found we've reached the end of the | |
4042 | (possibly empty) copy chain. */ | |
4043 | if (set == 0) | |
4044 | break; | |
4045 | ||
4046 | if (GET_CODE (set->expr) != SET) | |
4047 | abort (); | |
4048 | ||
4049 | src = SET_SRC (set->expr); | |
4050 | ||
4051 | /* We know the set is available. | |
4052 | Now check that SRC is ANTLOC (i.e. none of the source operands | |
4053 | have changed since the start of the block). | |
4054 | ||
4055 | If the source operand changed, we may still use it for the next | |
4056 | iteration of this loop, but we may not use it for substitutions. */ | |
4057 | ||
4058 | if (CONSTANT_P (src) || oprs_not_set_p (src, insn)) | |
4059 | set1 = set; | |
4060 | ||
4061 | /* If the source of the set is anything except a register, then | |
4062 | we have reached the end of the copy chain. */ | |
4063 | if (GET_CODE (src) != REG) | |
4064 | break; | |
4065 | ||
4066 | /* Follow the copy chain, ie start another iteration of the loop | |
4067 | and see if we have an available copy into SRC. */ | |
4068 | regno = REGNO (src); | |
4069 | } | |
4070 | ||
4071 | /* SET1 holds the last set that was available and anticipatable at | |
4072 | INSN. */ | |
4073 | return set1; | |
4074 | } | |
4075 | ||
4076 | /* Subroutine of cprop_insn that tries to propagate constants into | |
4077 | JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL | |
4078 | it is the instruction that immediately preceeds JUMP, and must be a | |
4079 | single SET of a register. FROM is what we will try to replace, | |
4080 | SRC is the constant we will try to substitute for it. Returns nonzero | |
4081 | if a change was made. */ | |
4082 | ||
4083 | static int | |
4084 | cprop_jump (bb, setcc, jump, from, src) | |
4085 | basic_block bb; | |
4086 | rtx setcc; | |
4087 | rtx jump; | |
4088 | rtx from; | |
4089 | rtx src; | |
4090 | { | |
4091 | rtx new, new_set; | |
4092 | rtx set = pc_set (jump); | |
4093 | ||
4094 | /* First substitute in the INSN condition as the SET_SRC of the JUMP, | |
4095 | then substitute that given values in this expanded JUMP. */ | |
4096 | if (setcc != NULL) | |
4097 | { | |
4098 | rtx setcc_set = single_set (setcc); | |
4099 | new_set = simplify_replace_rtx (SET_SRC (set), | |
4100 | SET_DEST (setcc_set), | |
4101 | SET_SRC (setcc_set)); | |
4102 | } | |
4103 | else | |
4104 | new_set = set; | |
4105 | ||
4106 | new = simplify_replace_rtx (new_set, from, src); | |
4107 | ||
4108 | /* If no simplification can be made, then try the next | |
4109 | register. */ | |
4110 | if (rtx_equal_p (new, new_set)) | |
4111 | return 0; | |
4112 | ||
4113 | /* If this is now a no-op delete it, otherwise this must be a valid insn. */ | |
4114 | if (new == pc_rtx) | |
4115 | delete_insn (jump); | |
4116 | else | |
4117 | { | |
4118 | if (! validate_change (jump, &SET_SRC (set), new, 0)) | |
4119 | return 0; | |
4120 | ||
4121 | /* If this has turned into an unconditional jump, | |
4122 | then put a barrier after it so that the unreachable | |
4123 | code will be deleted. */ | |
4124 | if (GET_CODE (SET_SRC (set)) == LABEL_REF) | |
4125 | emit_barrier_after (jump); | |
4126 | } | |
4127 | ||
4128 | #ifdef HAVE_cc0 | |
4129 | /* Delete the cc0 setter. */ | |
4130 | if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc)))) | |
4131 | delete_insn (setcc); | |
4132 | #endif | |
4133 | ||
4134 | run_jump_opt_after_gcse = 1; | |
4135 | ||
4136 | const_prop_count++; | |
4137 | if (gcse_file != NULL) | |
4138 | { | |
4139 | fprintf (gcse_file, | |
4140 | "CONST-PROP: Replacing reg %d in jump_insn %d with constant ", | |
4141 | REGNO (from), INSN_UID (jump)); | |
4142 | print_rtl (gcse_file, src); | |
4143 | fprintf (gcse_file, "\n"); | |
4144 | } | |
4145 | purge_dead_edges (bb); | |
4146 | ||
4147 | return 1; | |
4148 | } | |
4149 | ||
4150 | static bool | |
4151 | constprop_register (insn, from, to, alter_jumps) | |
4152 | rtx insn; | |
4153 | rtx from; | |
4154 | rtx to; | |
4155 | int alter_jumps; | |
4156 | { | |
4157 | rtx sset; | |
4158 | ||
4159 | /* Check for reg or cc0 setting instructions followed by | |
4160 | conditional branch instructions first. */ | |
4161 | if (alter_jumps | |
4162 | && (sset = single_set (insn)) != NULL | |
4163 | && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn))) | |
4164 | { | |
4165 | rtx dest = SET_DEST (sset); | |
4166 | if ((REG_P (dest) || CC0_P (dest)) | |
4167 | && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), from, to)) | |
4168 | return 1; | |
4169 | } | |
4170 | ||
4171 | /* Handle normal insns next. */ | |
4172 | if (GET_CODE (insn) == INSN | |
4173 | && try_replace_reg (from, to, insn)) | |
4174 | return 1; | |
4175 | ||
4176 | /* Try to propagate a CONST_INT into a conditional jump. | |
4177 | We're pretty specific about what we will handle in this | |
4178 | code, we can extend this as necessary over time. | |
4179 | ||
4180 | Right now the insn in question must look like | |
4181 | (set (pc) (if_then_else ...)) */ | |
4182 | else if (alter_jumps && any_condjump_p (insn) && onlyjump_p (insn)) | |
4183 | return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, to); | |
4184 | return 0; | |
4185 | } | |
4186 | ||
4187 | /* Perform constant and copy propagation on INSN. | |
4188 | The result is non-zero if a change was made. */ | |
4189 | ||
4190 | static int | |
4191 | cprop_insn (insn, alter_jumps) | |
4192 | rtx insn; | |
4193 | int alter_jumps; | |
4194 | { | |
4195 | struct reg_use *reg_used; | |
4196 | int changed = 0; | |
4197 | rtx note; | |
4198 | ||
4199 | if (!INSN_P (insn)) | |
4200 | return 0; | |
4201 | ||
4202 | reg_use_count = 0; | |
4203 | note_uses (&PATTERN (insn), find_used_regs, NULL); | |
4204 | ||
4205 | note = find_reg_equal_equiv_note (insn); | |
4206 | ||
4207 | /* We may win even when propagating constants into notes. */ | |
4208 | if (note) | |
4209 | find_used_regs (&XEXP (note, 0), NULL); | |
4210 | ||
4211 | for (reg_used = ®_use_table[0]; reg_use_count > 0; | |
4212 | reg_used++, reg_use_count--) | |
4213 | { | |
4214 | unsigned int regno = REGNO (reg_used->reg_rtx); | |
4215 | rtx pat, src; | |
4216 | struct expr *set; | |
4217 | ||
4218 | /* Ignore registers created by GCSE. | |
4219 | We do this because ... */ | |
4220 | if (regno >= max_gcse_regno) | |
4221 | continue; | |
4222 | ||
4223 | /* If the register has already been set in this block, there's | |
4224 | nothing we can do. */ | |
4225 | if (! oprs_not_set_p (reg_used->reg_rtx, insn)) | |
4226 | continue; | |
4227 | ||
4228 | /* Find an assignment that sets reg_used and is available | |
4229 | at the start of the block. */ | |
4230 | set = find_avail_set (regno, insn); | |
4231 | if (! set) | |
4232 | continue; | |
4233 | ||
4234 | pat = set->expr; | |
4235 | /* ??? We might be able to handle PARALLELs. Later. */ | |
4236 | if (GET_CODE (pat) != SET) | |
4237 | abort (); | |
4238 | ||
4239 | src = SET_SRC (pat); | |
4240 | ||
4241 | /* Constant propagation. */ | |
4242 | if (CONSTANT_P (src)) | |
4243 | { | |
4244 | if (constprop_register (insn, reg_used->reg_rtx, src, alter_jumps)) | |
4245 | { | |
4246 | changed = 1; | |
4247 | const_prop_count++; | |
4248 | if (gcse_file != NULL) | |
4249 | { | |
4250 | fprintf (gcse_file, "GLOBAL CONST-PROP: Replacing reg %d in ", regno); | |
4251 | fprintf (gcse_file, "insn %d with constant ", INSN_UID (insn)); | |
4252 | print_rtl (gcse_file, src); | |
4253 | fprintf (gcse_file, "\n"); | |
4254 | } | |
4255 | } | |
4256 | } | |
4257 | else if (GET_CODE (src) == REG | |
4258 | && REGNO (src) >= FIRST_PSEUDO_REGISTER | |
4259 | && REGNO (src) != regno) | |
4260 | { | |
4261 | if (try_replace_reg (reg_used->reg_rtx, src, insn)) | |
4262 | { | |
4263 | changed = 1; | |
4264 | copy_prop_count++; | |
4265 | if (gcse_file != NULL) | |
4266 | { | |
4267 | fprintf (gcse_file, "GLOBAL COPY-PROP: Replacing reg %d in insn %d", | |
4268 | regno, INSN_UID (insn)); | |
4269 | fprintf (gcse_file, " with reg %d\n", REGNO (src)); | |
4270 | } | |
4271 | ||
4272 | /* The original insn setting reg_used may or may not now be | |
4273 | deletable. We leave the deletion to flow. */ | |
4274 | /* FIXME: If it turns out that the insn isn't deletable, | |
4275 | then we may have unnecessarily extended register lifetimes | |
4276 | and made things worse. */ | |
4277 | } | |
4278 | } | |
4279 | } | |
4280 | ||
4281 | return changed; | |
4282 | } | |
4283 | ||
4284 | static bool | |
4285 | do_local_cprop (x, insn, alter_jumps) | |
4286 | rtx x; | |
4287 | rtx insn; | |
4288 | int alter_jumps; | |
4289 | { | |
4290 | rtx newreg = NULL, newcnst = NULL; | |
4291 | ||
4292 | /* Rule out USE instructions and ASM statements as we don't want to change the hard | |
4293 | registers mentioned. */ | |
4294 | if (GET_CODE (x) == REG | |
4295 | && (REGNO (x) >= FIRST_PSEUDO_REGISTER | |
4296 | || (GET_CODE (PATTERN (insn)) != USE && asm_noperands (PATTERN (insn)) < 0))) | |
4297 | { | |
4298 | cselib_val *val = cselib_lookup (x, GET_MODE (x), 0); | |
4299 | struct elt_loc_list *l; | |
4300 | ||
4301 | if (!val) | |
4302 | return false; | |
4303 | for (l = val->locs; l; l = l->next) | |
4304 | { | |
4305 | rtx this_rtx = l->loc; | |
4306 | rtx note; | |
4307 | ||
4308 | if (CONSTANT_P (this_rtx)) | |
4309 | newcnst = this_rtx; | |
4310 | if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER | |
4311 | /* Don't copy propagate if it has attached REG_EQUIV note. | |
4312 | At this point this only function parameters should have | |
4313 | REG_EQUIV notes and if the argument slot is used somewhere | |
4314 | explicitly, it means address of parameter has been taken, | |
4315 | so we should not extend the lifetime of the pseudo. */ | |
4316 | && (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX)) | |
4317 | || GET_CODE (XEXP (note, 0)) != MEM)) | |
4318 | newreg = this_rtx; | |
4319 | } | |
4320 | if (newcnst && constprop_register (insn, x, newcnst, alter_jumps)) | |
4321 | { | |
4322 | if (gcse_file != NULL) | |
4323 | { | |
4324 | fprintf (gcse_file, "LOCAL CONST-PROP: Replacing reg %d in ", | |
4325 | REGNO (x)); | |
4326 | fprintf (gcse_file, "insn %d with constant ", | |
4327 | INSN_UID (insn)); | |
4328 | print_rtl (gcse_file, newcnst); | |
4329 | fprintf (gcse_file, "\n"); | |
4330 | } | |
4331 | const_prop_count++; | |
4332 | return true; | |
4333 | } | |
4334 | else if (newreg && newreg != x && try_replace_reg (x, newreg, insn)) | |
4335 | { | |
4336 | if (gcse_file != NULL) | |
4337 | { | |
4338 | fprintf (gcse_file, | |
4339 | "LOCAL COPY-PROP: Replacing reg %d in insn %d", | |
4340 | REGNO (x), INSN_UID (insn)); | |
4341 | fprintf (gcse_file, " with reg %d\n", REGNO (newreg)); | |
4342 | } | |
4343 | copy_prop_count++; | |
4344 | return true; | |
4345 | } | |
4346 | } | |
4347 | return false; | |
4348 | } | |
4349 | ||
4350 | static void | |
4351 | local_cprop_pass (alter_jumps) | |
4352 | int alter_jumps; | |
4353 | { | |
4354 | rtx insn; | |
4355 | struct reg_use *reg_used; | |
4356 | ||
4357 | cselib_init (); | |
4358 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) | |
4359 | { | |
4360 | if (INSN_P (insn)) | |
4361 | { | |
4362 | rtx note = find_reg_equal_equiv_note (insn); | |
4363 | ||
4364 | do | |
4365 | { | |
4366 | reg_use_count = 0; | |
4367 | note_uses (&PATTERN (insn), find_used_regs, NULL); | |
4368 | if (note) | |
4369 | find_used_regs (&XEXP (note, 0), NULL); | |
4370 | ||
4371 | for (reg_used = ®_use_table[0]; reg_use_count > 0; | |
4372 | reg_used++, reg_use_count--) | |
4373 | if (do_local_cprop (reg_used->reg_rtx, insn, alter_jumps)) | |
4374 | break; | |
4375 | } | |
4376 | while (reg_use_count); | |
4377 | } | |
4378 | cselib_process_insn (insn); | |
4379 | } | |
4380 | cselib_finish (); | |
4381 | } | |
4382 | ||
4383 | /* Forward propagate copies. This includes copies and constants. Return | |
4384 | non-zero if a change was made. */ | |
4385 | ||
4386 | static int | |
4387 | cprop (alter_jumps) | |
4388 | int alter_jumps; | |
4389 | { | |
4390 | int changed; | |
4391 | basic_block bb; | |
4392 | rtx insn; | |
4393 | ||
4394 | /* Note we start at block 1. */ | |
4395 | if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR) | |
4396 | { | |
4397 | if (gcse_file != NULL) | |
4398 | fprintf (gcse_file, "\n"); | |
4399 | return 0; | |
4400 | } | |
4401 | ||
4402 | changed = 0; | |
4403 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb) | |
4404 | { | |
4405 | /* Reset tables used to keep track of what's still valid [since the | |
4406 | start of the block]. */ | |
4407 | reset_opr_set_tables (); | |
4408 | ||
4409 | for (insn = bb->head; | |
4410 | insn != NULL && insn != NEXT_INSN (bb->end); | |
4411 | insn = NEXT_INSN (insn)) | |
4412 | if (INSN_P (insn)) | |
4413 | { | |
4414 | changed |= cprop_insn (insn, alter_jumps); | |
4415 | ||
4416 | /* Keep track of everything modified by this insn. */ | |
4417 | /* ??? Need to be careful w.r.t. mods done to INSN. Don't | |
4418 | call mark_oprs_set if we turned the insn into a NOTE. */ | |
4419 | if (GET_CODE (insn) != NOTE) | |
4420 | mark_oprs_set (insn); | |
4421 | } | |
4422 | } | |
4423 | ||
4424 | if (gcse_file != NULL) | |
4425 | fprintf (gcse_file, "\n"); | |
4426 | ||
4427 | return changed; | |
4428 | } | |
4429 | ||
4430 | /* Perform one copy/constant propagation pass. | |
4431 | F is the first insn in the function. | |
4432 | PASS is the pass count. */ | |
4433 | ||
4434 | static int | |
4435 | one_cprop_pass (pass, alter_jumps) | |
4436 | int pass; | |
4437 | int alter_jumps; | |
4438 | { | |
4439 | int changed = 0; | |
4440 | ||
4441 | const_prop_count = 0; | |
4442 | copy_prop_count = 0; | |
4443 | ||
4444 | local_cprop_pass (alter_jumps); | |
4445 | ||
4446 | alloc_set_hash_table (max_cuid); | |
4447 | compute_set_hash_table (); | |
4448 | if (gcse_file) | |
4449 | dump_hash_table (gcse_file, "SET", set_hash_table, set_hash_table_size, | |
4450 | n_sets); | |
4451 | if (n_sets > 0) | |
4452 | { | |
4453 | alloc_cprop_mem (last_basic_block, n_sets); | |
4454 | compute_cprop_data (); | |
4455 | changed = cprop (alter_jumps); | |
4456 | if (alter_jumps) | |
4457 | changed |= bypass_conditional_jumps (); | |
4458 | free_cprop_mem (); | |
4459 | } | |
4460 | ||
4461 | free_set_hash_table (); | |
4462 | ||
4463 | if (gcse_file) | |
4464 | { | |
4465 | fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, ", | |
4466 | current_function_name, pass, bytes_used); | |
4467 | fprintf (gcse_file, "%d const props, %d copy props\n\n", | |
4468 | const_prop_count, copy_prop_count); | |
4469 | } | |
4470 | ||
4471 | return changed; | |
4472 | } | |
4473 | \f | |
4474 | /* Bypass conditional jumps. */ | |
4475 | ||
4476 | /* Find a set of REGNO to a constant that is available at the end of basic | |
4477 | block BB. Returns NULL if no such set is found. Based heavily upon | |
4478 | find_avail_set. */ | |
4479 | ||
4480 | static struct expr * | |
4481 | find_bypass_set (regno, bb) | |
4482 | int regno; | |
4483 | int bb; | |
4484 | { | |
4485 | struct expr *result = 0; | |
4486 | ||
4487 | for (;;) | |
4488 | { | |
4489 | rtx src; | |
4490 | struct expr *set = lookup_set (regno, NULL_RTX); | |
4491 | ||
4492 | while (set) | |
4493 | { | |
4494 | if (TEST_BIT (cprop_avout[bb], set->bitmap_index)) | |
4495 | break; | |
4496 | set = next_set (regno, set); | |
4497 | } | |
4498 | ||
4499 | if (set == 0) | |
4500 | break; | |
4501 | ||
4502 | if (GET_CODE (set->expr) != SET) | |
4503 | abort (); | |
4504 | ||
4505 | src = SET_SRC (set->expr); | |
4506 | if (CONSTANT_P (src)) | |
4507 | result = set; | |
4508 | ||
4509 | if (GET_CODE (src) != REG) | |
4510 | break; | |
4511 | ||
4512 | regno = REGNO (src); | |
4513 | } | |
4514 | return result; | |
4515 | } | |
4516 | ||
4517 | ||
4518 | /* Subroutine of bypass_conditional_jumps that attempts to bypass the given | |
4519 | basic block BB which has more than one predecessor. If not NULL, SETCC | |
4520 | is the first instruction of BB, which is immediately followed by JUMP_INSN | |
4521 | JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB. | |
4522 | Returns nonzero if a change was made. */ | |
4523 | ||
4524 | static int | |
4525 | bypass_block (bb, setcc, jump) | |
4526 | basic_block bb; | |
4527 | rtx setcc, jump; | |
4528 | { | |
4529 | rtx insn, note; | |
4530 | edge e, enext; | |
4531 | int i, change; | |
4532 | ||
4533 | insn = (setcc != NULL) ? setcc : jump; | |
4534 | ||
4535 | /* Determine set of register uses in INSN. */ | |
4536 | reg_use_count = 0; | |
4537 | note_uses (&PATTERN (insn), find_used_regs, NULL); | |
4538 | note = find_reg_equal_equiv_note (insn); | |
4539 | if (note) | |
4540 | find_used_regs (&XEXP (note, 0), NULL); | |
4541 | ||
4542 | change = 0; | |
4543 | for (e = bb->pred; e; e = enext) | |
4544 | { | |
4545 | enext = e->pred_next; | |
4546 | for (i = 0; i < reg_use_count; i++) | |
4547 | { | |
4548 | struct reg_use *reg_used = ®_use_table[i]; | |
4549 | unsigned int regno = REGNO (reg_used->reg_rtx); | |
4550 | basic_block dest, old_dest; | |
4551 | struct expr *set; | |
4552 | rtx src, new; | |
4553 | ||
4554 | if (regno >= max_gcse_regno) | |
4555 | continue; | |
4556 | ||
4557 | set = find_bypass_set (regno, e->src->index); | |
4558 | ||
4559 | if (! set) | |
4560 | continue; | |
4561 | ||
4562 | src = SET_SRC (pc_set (jump)); | |
4563 | ||
4564 | if (setcc != NULL) | |
4565 | src = simplify_replace_rtx (src, | |
4566 | SET_DEST (PATTERN (setcc)), | |
4567 | SET_SRC (PATTERN (setcc))); | |
4568 | ||
4569 | new = simplify_replace_rtx (src, reg_used->reg_rtx, | |
4570 | SET_SRC (set->expr)); | |
4571 | ||
4572 | if (new == pc_rtx) | |
4573 | dest = FALLTHRU_EDGE (bb)->dest; | |
4574 | else if (GET_CODE (new) == LABEL_REF) | |
4575 | dest = BRANCH_EDGE (bb)->dest; | |
4576 | else | |
4577 | dest = NULL; | |
4578 | ||
4579 | /* Once basic block indices are stable, we should be able | |
4580 | to use redirect_edge_and_branch_force instead. */ | |
4581 | old_dest = e->dest; | |
4582 | if (dest != NULL && dest != old_dest | |
4583 | && redirect_edge_and_branch (e, dest)) | |
4584 | { | |
4585 | /* Copy the register setter to the redirected edge. | |
4586 | Don't copy CC0 setters, as CC0 is dead after jump. */ | |
4587 | if (setcc) | |
4588 | { | |
4589 | rtx pat = PATTERN (setcc); | |
4590 | if (!CC0_P (SET_DEST (pat))) | |
4591 | insert_insn_on_edge (copy_insn (pat), e); | |
4592 | } | |
4593 | ||
4594 | if (gcse_file != NULL) | |
4595 | { | |
4596 | fprintf (gcse_file, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ", | |
4597 | regno, INSN_UID (jump)); | |
4598 | print_rtl (gcse_file, SET_SRC (set->expr)); | |
4599 | fprintf (gcse_file, "\nBypass edge from %d->%d to %d\n", | |
4600 | e->src->index, old_dest->index, dest->index); | |
4601 | } | |
4602 | change = 1; | |
4603 | break; | |
4604 | } | |
4605 | } | |
4606 | } | |
4607 | return change; | |
4608 | } | |
4609 | ||
4610 | /* Find basic blocks with more than one predecessor that only contain a | |
4611 | single conditional jump. If the result of the comparison is known at | |
4612 | compile-time from any incoming edge, redirect that edge to the | |
4613 | appropriate target. Returns nonzero if a change was made. */ | |
4614 | ||
4615 | static int | |
4616 | bypass_conditional_jumps () | |
4617 | { | |
4618 | basic_block bb; | |
4619 | int changed; | |
4620 | rtx setcc; | |
4621 | rtx insn; | |
4622 | rtx dest; | |
4623 | ||
4624 | /* Note we start at block 1. */ | |
4625 | if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR) | |
4626 | return 0; | |
4627 | ||
4628 | changed = 0; | |
4629 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, | |
4630 | EXIT_BLOCK_PTR, next_bb) | |
4631 | { | |
4632 | /* Check for more than one predecessor. */ | |
4633 | if (bb->pred && bb->pred->pred_next) | |
4634 | { | |
4635 | setcc = NULL_RTX; | |
4636 | for (insn = bb->head; | |
4637 | insn != NULL && insn != NEXT_INSN (bb->end); | |
4638 | insn = NEXT_INSN (insn)) | |
4639 | if (GET_CODE (insn) == INSN) | |
4640 | { | |
4641 | if (setcc) | |
4642 | break; | |
4643 | if (GET_CODE (PATTERN (insn)) != SET) | |
4644 | break; | |
4645 | ||
4646 | dest = SET_DEST (PATTERN (insn)); | |
4647 | if (REG_P (dest) || CC0_P (dest)) | |
4648 | setcc = insn; | |
4649 | else | |
4650 | break; | |
4651 | } | |
4652 | else if (GET_CODE (insn) == JUMP_INSN) | |
4653 | { | |
4654 | if (any_condjump_p (insn) && onlyjump_p (insn)) | |
4655 | changed |= bypass_block (bb, setcc, insn); | |
4656 | break; | |
4657 | } | |
4658 | else if (INSN_P (insn)) | |
4659 | break; | |
4660 | } | |
4661 | } | |
4662 | ||
4663 | /* If we bypassed any register setting insns, we inserted a | |
4664 | copy on the redirected edge. These need to be commited. */ | |
4665 | if (changed) | |
4666 | commit_edge_insertions(); | |
4667 | ||
4668 | return changed; | |
4669 | } | |
4670 | \f | |
4671 | /* Compute PRE+LCM working variables. */ | |
4672 | ||
4673 | /* Local properties of expressions. */ | |
4674 | /* Nonzero for expressions that are transparent in the block. */ | |
4675 | static sbitmap *transp; | |
4676 | ||
4677 | /* Nonzero for expressions that are transparent at the end of the block. | |
4678 | This is only zero for expressions killed by abnormal critical edge | |
4679 | created by a calls. */ | |
4680 | static sbitmap *transpout; | |
4681 | ||
4682 | /* Nonzero for expressions that are computed (available) in the block. */ | |
4683 | static sbitmap *comp; | |
4684 | ||
4685 | /* Nonzero for expressions that are locally anticipatable in the block. */ | |
4686 | static sbitmap *antloc; | |
4687 | ||
4688 | /* Nonzero for expressions where this block is an optimal computation | |
4689 | point. */ | |
4690 | static sbitmap *pre_optimal; | |
4691 | ||
4692 | /* Nonzero for expressions which are redundant in a particular block. */ | |
4693 | static sbitmap *pre_redundant; | |
4694 | ||
4695 | /* Nonzero for expressions which should be inserted on a specific edge. */ | |
4696 | static sbitmap *pre_insert_map; | |
4697 | ||
4698 | /* Nonzero for expressions which should be deleted in a specific block. */ | |
4699 | static sbitmap *pre_delete_map; | |
4700 | ||
4701 | /* Contains the edge_list returned by pre_edge_lcm. */ | |
4702 | static struct edge_list *edge_list; | |
4703 | ||
4704 | /* Redundant insns. */ | |
4705 | static sbitmap pre_redundant_insns; | |
4706 | ||
4707 | /* Allocate vars used for PRE analysis. */ | |
4708 | ||
4709 | static void | |
4710 | alloc_pre_mem (n_blocks, n_exprs) | |
4711 | int n_blocks, n_exprs; | |
4712 | { | |
4713 | transp = sbitmap_vector_alloc (n_blocks, n_exprs); | |
4714 | comp = sbitmap_vector_alloc (n_blocks, n_exprs); | |
4715 | antloc = sbitmap_vector_alloc (n_blocks, n_exprs); | |
4716 | ||
4717 | pre_optimal = NULL; | |
4718 | pre_redundant = NULL; | |
4719 | pre_insert_map = NULL; | |
4720 | pre_delete_map = NULL; | |
4721 | ae_in = NULL; | |
4722 | ae_out = NULL; | |
4723 | ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs); | |
4724 | ||
4725 | /* pre_insert and pre_delete are allocated later. */ | |
4726 | } | |
4727 | ||
4728 | /* Free vars used for PRE analysis. */ | |
4729 | ||
4730 | static void | |
4731 | free_pre_mem () | |
4732 | { | |
4733 | sbitmap_vector_free (transp); | |
4734 | sbitmap_vector_free (comp); | |
4735 | ||
4736 | /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */ | |
4737 | ||
4738 | if (pre_optimal) | |
4739 | sbitmap_vector_free (pre_optimal); | |
4740 | if (pre_redundant) | |
4741 | sbitmap_vector_free (pre_redundant); | |
4742 | if (pre_insert_map) | |
4743 | sbitmap_vector_free (pre_insert_map); | |
4744 | if (pre_delete_map) | |
4745 | sbitmap_vector_free (pre_delete_map); | |
4746 | if (ae_in) | |
4747 | sbitmap_vector_free (ae_in); | |
4748 | if (ae_out) | |
4749 | sbitmap_vector_free (ae_out); | |
4750 | ||
4751 | transp = comp = NULL; | |
4752 | pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL; | |
4753 | ae_in = ae_out = NULL; | |
4754 | } | |
4755 | ||
4756 | /* Top level routine to do the dataflow analysis needed by PRE. */ | |
4757 | ||
4758 | static void | |
4759 | compute_pre_data () | |
4760 | { | |
4761 | sbitmap trapping_expr; | |
4762 | basic_block bb; | |
4763 | unsigned int ui; | |
4764 | ||
4765 | compute_local_properties (transp, comp, antloc, 0); | |
4766 | sbitmap_vector_zero (ae_kill, last_basic_block); | |
4767 | ||
4768 | /* Collect expressions which might trap. */ | |
4769 | trapping_expr = sbitmap_alloc (n_exprs); | |
4770 | sbitmap_zero (trapping_expr); | |
4771 | for (ui = 0; ui < expr_hash_table_size; ui++) | |
4772 | { | |
4773 | struct expr *e; | |
4774 | for (e = expr_hash_table[ui]; e != NULL; e = e->next_same_hash) | |
4775 | if (may_trap_p (e->expr)) | |
4776 | SET_BIT (trapping_expr, e->bitmap_index); | |
4777 | } | |
4778 | ||
4779 | /* Compute ae_kill for each basic block using: | |
4780 | ||
4781 | ~(TRANSP | COMP) | |
4782 | ||
4783 | This is significantly faster than compute_ae_kill. */ | |
4784 | ||
4785 | FOR_EACH_BB (bb) | |
4786 | { | |
4787 | edge e; | |
4788 | ||
4789 | /* If the current block is the destination of an abnormal edge, we | |
4790 | kill all trapping expressions because we won't be able to properly | |
4791 | place the instruction on the edge. So make them neither | |
4792 | anticipatable nor transparent. This is fairly conservative. */ | |
4793 | for (e = bb->pred; e ; e = e->pred_next) | |
4794 | if (e->flags & EDGE_ABNORMAL) | |
4795 | { | |
4796 | sbitmap_difference (antloc[bb->index], antloc[bb->index], trapping_expr); | |
4797 | sbitmap_difference (transp[bb->index], transp[bb->index], trapping_expr); | |
4798 | break; | |
4799 | } | |
4800 | ||
4801 | sbitmap_a_or_b (ae_kill[bb->index], transp[bb->index], comp[bb->index]); | |
4802 | sbitmap_not (ae_kill[bb->index], ae_kill[bb->index]); | |
4803 | } | |
4804 | ||
4805 | edge_list = pre_edge_lcm (gcse_file, n_exprs, transp, comp, antloc, | |
4806 | ae_kill, &pre_insert_map, &pre_delete_map); | |
4807 | sbitmap_vector_free (antloc); | |
4808 | antloc = NULL; | |
4809 | sbitmap_vector_free (ae_kill); | |
4810 | ae_kill = NULL; | |
4811 | sbitmap_free (trapping_expr); | |
4812 | } | |
4813 | \f | |
4814 | /* PRE utilities */ | |
4815 | ||
4816 | /* Return non-zero if an occurrence of expression EXPR in OCCR_BB would reach | |
4817 | block BB. | |
4818 | ||
4819 | VISITED is a pointer to a working buffer for tracking which BB's have | |
4820 | been visited. It is NULL for the top-level call. | |
4821 | ||
4822 | We treat reaching expressions that go through blocks containing the same | |
4823 | reaching expression as "not reaching". E.g. if EXPR is generated in blocks | |
4824 | 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block | |
4825 | 2 as not reaching. The intent is to improve the probability of finding | |
4826 | only one reaching expression and to reduce register lifetimes by picking | |
4827 | the closest such expression. */ | |
4828 | ||
4829 | static int | |
4830 | pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited) | |
4831 | basic_block occr_bb; | |
4832 | struct expr *expr; | |
4833 | basic_block bb; | |
4834 | char *visited; | |
4835 | { | |
4836 | edge pred; | |
4837 | ||
4838 | for (pred = bb->pred; pred != NULL; pred = pred->pred_next) | |
4839 | { | |
4840 | basic_block pred_bb = pred->src; | |
4841 | ||
4842 | if (pred->src == ENTRY_BLOCK_PTR | |
4843 | /* Has predecessor has already been visited? */ | |
4844 | || visited[pred_bb->index]) | |
4845 | ;/* Nothing to do. */ | |
4846 | ||
4847 | /* Does this predecessor generate this expression? */ | |
4848 | else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index)) | |
4849 | { | |
4850 | /* Is this the occurrence we're looking for? | |
4851 | Note that there's only one generating occurrence per block | |
4852 | so we just need to check the block number. */ | |
4853 | if (occr_bb == pred_bb) | |
4854 | return 1; | |
4855 | ||
4856 | visited[pred_bb->index] = 1; | |
4857 | } | |
4858 | /* Ignore this predecessor if it kills the expression. */ | |
4859 | else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index)) | |
4860 | visited[pred_bb->index] = 1; | |
4861 | ||
4862 | /* Neither gen nor kill. */ | |
4863 | else | |
4864 | { | |
4865 | visited[pred_bb->index] = 1; | |
4866 | if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited)) | |
4867 | return 1; | |
4868 | } | |
4869 | } | |
4870 | ||
4871 | /* All paths have been checked. */ | |
4872 | return 0; | |
4873 | } | |
4874 | ||
4875 | /* The wrapper for pre_expr_reaches_here_work that ensures that any | |
4876 | memory allocated for that function is returned. */ | |
4877 | ||
4878 | static int | |
4879 | pre_expr_reaches_here_p (occr_bb, expr, bb) | |
4880 | basic_block occr_bb; | |
4881 | struct expr *expr; | |
4882 | basic_block bb; | |
4883 | { | |
4884 | int rval; | |
4885 | char *visited = (char *) xcalloc (last_basic_block, 1); | |
4886 | ||
4887 | rval = pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited); | |
4888 | ||
4889 | free (visited); | |
4890 | return rval; | |
4891 | } | |
4892 | \f | |
4893 | ||
4894 | /* Given an expr, generate RTL which we can insert at the end of a BB, | |
4895 | or on an edge. Set the block number of any insns generated to | |
4896 | the value of BB. */ | |
4897 | ||
4898 | static rtx | |
4899 | process_insert_insn (expr) | |
4900 | struct expr *expr; | |
4901 | { | |
4902 | rtx reg = expr->reaching_reg; | |
4903 | rtx exp = copy_rtx (expr->expr); | |
4904 | rtx pat; | |
4905 | ||
4906 | start_sequence (); | |
4907 | ||
4908 | /* If the expression is something that's an operand, like a constant, | |
4909 | just copy it to a register. */ | |
4910 | if (general_operand (exp, GET_MODE (reg))) | |
4911 | emit_move_insn (reg, exp); | |
4912 | ||
4913 | /* Otherwise, make a new insn to compute this expression and make sure the | |
4914 | insn will be recognized (this also adds any needed CLOBBERs). Copy the | |
4915 | expression to make sure we don't have any sharing issues. */ | |
4916 | else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode, reg, exp)))) | |
4917 | abort (); | |
4918 | ||
4919 | pat = get_insns (); | |
4920 | end_sequence (); | |
4921 | ||
4922 | return pat; | |
4923 | } | |
4924 | ||
4925 | /* Add EXPR to the end of basic block BB. | |
4926 | ||
4927 | This is used by both the PRE and code hoisting. | |
4928 | ||
4929 | For PRE, we want to verify that the expr is either transparent | |
4930 | or locally anticipatable in the target block. This check makes | |
4931 | no sense for code hoisting. */ | |
4932 | ||
4933 | static void | |
4934 | insert_insn_end_bb (expr, bb, pre) | |
4935 | struct expr *expr; | |
4936 | basic_block bb; | |
4937 | int pre; | |
4938 | { | |
4939 | rtx insn = bb->end; | |
4940 | rtx new_insn; | |
4941 | rtx reg = expr->reaching_reg; | |
4942 | int regno = REGNO (reg); | |
4943 | rtx pat, pat_end; | |
4944 | ||
4945 | pat = process_insert_insn (expr); | |
4946 | if (pat == NULL_RTX || ! INSN_P (pat)) | |
4947 | abort (); | |
4948 | ||
4949 | pat_end = pat; | |
4950 | while (NEXT_INSN (pat_end) != NULL_RTX) | |
4951 | pat_end = NEXT_INSN (pat_end); | |
4952 | ||
4953 | /* If the last insn is a jump, insert EXPR in front [taking care to | |
4954 | handle cc0, etc. properly]. Similary we need to care trapping | |
4955 | instructions in presence of non-call exceptions. */ | |
4956 | ||
4957 | if (GET_CODE (insn) == JUMP_INSN | |
4958 | || (GET_CODE (insn) == INSN | |
4959 | && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL)))) | |
4960 | { | |
4961 | #ifdef HAVE_cc0 | |
4962 | rtx note; | |
4963 | #endif | |
4964 | /* It should always be the case that we can put these instructions | |
4965 | anywhere in the basic block with performing PRE optimizations. | |
4966 | Check this. */ | |
4967 | if (GET_CODE (insn) == INSN && pre | |
4968 | && !TEST_BIT (antloc[bb->index], expr->bitmap_index) | |
4969 | && !TEST_BIT (transp[bb->index], expr->bitmap_index)) | |
4970 | abort (); | |
4971 | ||
4972 | /* If this is a jump table, then we can't insert stuff here. Since | |
4973 | we know the previous real insn must be the tablejump, we insert | |
4974 | the new instruction just before the tablejump. */ | |
4975 | if (GET_CODE (PATTERN (insn)) == ADDR_VEC | |
4976 | || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) | |
4977 | insn = prev_real_insn (insn); | |
4978 | ||
4979 | #ifdef HAVE_cc0 | |
4980 | /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts | |
4981 | if cc0 isn't set. */ | |
4982 | note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX); | |
4983 | if (note) | |
4984 | insn = XEXP (note, 0); | |
4985 | else | |
4986 | { | |
4987 | rtx maybe_cc0_setter = prev_nonnote_insn (insn); | |
4988 | if (maybe_cc0_setter | |
4989 | && INSN_P (maybe_cc0_setter) | |
4990 | && sets_cc0_p (PATTERN (maybe_cc0_setter))) | |
4991 | insn = maybe_cc0_setter; | |
4992 | } | |
4993 | #endif | |
4994 | /* FIXME: What if something in cc0/jump uses value set in new insn? */ | |
4995 | new_insn = emit_insn_before (pat, insn); | |
4996 | } | |
4997 | ||
4998 | /* Likewise if the last insn is a call, as will happen in the presence | |
4999 | of exception handling. */ | |
5000 | else if (GET_CODE (insn) == CALL_INSN | |
5001 | && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL))) | |
5002 | { | |
5003 | /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers, | |
5004 | we search backward and place the instructions before the first | |
5005 | parameter is loaded. Do this for everyone for consistency and a | |
5006 | presumtion that we'll get better code elsewhere as well. | |
5007 | ||
5008 | It should always be the case that we can put these instructions | |
5009 | anywhere in the basic block with performing PRE optimizations. | |
5010 | Check this. */ | |
5011 | ||
5012 | if (pre | |
5013 | && !TEST_BIT (antloc[bb->index], expr->bitmap_index) | |
5014 | && !TEST_BIT (transp[bb->index], expr->bitmap_index)) | |
5015 | abort (); | |
5016 | ||
5017 | /* Since different machines initialize their parameter registers | |
5018 | in different orders, assume nothing. Collect the set of all | |
5019 | parameter registers. */ | |
5020 | insn = find_first_parameter_load (insn, bb->head); | |
5021 | ||
5022 | /* If we found all the parameter loads, then we want to insert | |
5023 | before the first parameter load. | |
5024 | ||
5025 | If we did not find all the parameter loads, then we might have | |
5026 | stopped on the head of the block, which could be a CODE_LABEL. | |
5027 | If we inserted before the CODE_LABEL, then we would be putting | |
5028 | the insn in the wrong basic block. In that case, put the insn | |
5029 | after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */ | |
5030 | while (GET_CODE (insn) == CODE_LABEL | |
5031 | || NOTE_INSN_BASIC_BLOCK_P (insn)) | |
5032 | insn = NEXT_INSN (insn); | |
5033 | ||
5034 | new_insn = emit_insn_before (pat, insn); | |
5035 | } | |
5036 | else | |
5037 | new_insn = emit_insn_after (pat, insn); | |
5038 | ||
5039 | while (1) | |
5040 | { | |
5041 | if (INSN_P (pat)) | |
5042 | { | |
5043 | add_label_notes (PATTERN (pat), new_insn); | |
5044 | note_stores (PATTERN (pat), record_set_info, pat); | |
5045 | } | |
5046 | if (pat == pat_end) | |
5047 | break; | |
5048 | pat = NEXT_INSN (pat); | |
5049 | } | |
5050 | ||
5051 | gcse_create_count++; | |
5052 | ||
5053 | if (gcse_file) | |
5054 | { | |
5055 | fprintf (gcse_file, "PRE/HOIST: end of bb %d, insn %d, ", | |
5056 | bb->index, INSN_UID (new_insn)); | |
5057 | fprintf (gcse_file, "copying expression %d to reg %d\n", | |
5058 | expr->bitmap_index, regno); | |
5059 | } | |
5060 | } | |
5061 | ||
5062 | /* Insert partially redundant expressions on edges in the CFG to make | |
5063 | the expressions fully redundant. */ | |
5064 | ||
5065 | static int | |
5066 | pre_edge_insert (edge_list, index_map) | |
5067 | struct edge_list *edge_list; | |
5068 | struct expr **index_map; | |
5069 | { | |
5070 | int e, i, j, num_edges, set_size, did_insert = 0; | |
5071 | sbitmap *inserted; | |
5072 | ||
5073 | /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge | |
5074 | if it reaches any of the deleted expressions. */ | |
5075 | ||
5076 | set_size = pre_insert_map[0]->size; | |
5077 | num_edges = NUM_EDGES (edge_list); | |
5078 | inserted = sbitmap_vector_alloc (num_edges, n_exprs); | |
5079 | sbitmap_vector_zero (inserted, num_edges); | |
5080 | ||
5081 | for (e = 0; e < num_edges; e++) | |
5082 | { | |
5083 | int indx; | |
5084 | basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e); | |
5085 | ||
5086 | for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS) | |
5087 | { | |
5088 | SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i]; | |
5089 | ||
5090 | for (j = indx; insert && j < n_exprs; j++, insert >>= 1) | |
5091 | if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX) | |
5092 | { | |
5093 | struct expr *expr = index_map[j]; | |
5094 | struct occr *occr; | |
5095 | ||
5096 | /* Now look at each deleted occurrence of this expression. */ | |
5097 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
5098 | { | |
5099 | if (! occr->deleted_p) | |
5100 | continue; | |
5101 | ||
5102 | /* Insert this expression on this edge if if it would | |
5103 | reach the deleted occurrence in BB. */ | |
5104 | if (!TEST_BIT (inserted[e], j)) | |
5105 | { | |
5106 | rtx insn; | |
5107 | edge eg = INDEX_EDGE (edge_list, e); | |
5108 | ||
5109 | /* We can't insert anything on an abnormal and | |
5110 | critical edge, so we insert the insn at the end of | |
5111 | the previous block. There are several alternatives | |
5112 | detailed in Morgans book P277 (sec 10.5) for | |
5113 | handling this situation. This one is easiest for | |
5114 | now. */ | |
5115 | ||
5116 | if ((eg->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL) | |
5117 | insert_insn_end_bb (index_map[j], bb, 0); | |
5118 | else | |
5119 | { | |
5120 | insn = process_insert_insn (index_map[j]); | |
5121 | insert_insn_on_edge (insn, eg); | |
5122 | } | |
5123 | ||
5124 | if (gcse_file) | |
5125 | { | |
5126 | fprintf (gcse_file, "PRE/HOIST: edge (%d,%d), ", | |
5127 | bb->index, | |
5128 | INDEX_EDGE_SUCC_BB (edge_list, e)->index); | |
5129 | fprintf (gcse_file, "copy expression %d\n", | |
5130 | expr->bitmap_index); | |
5131 | } | |
5132 | ||
5133 | update_ld_motion_stores (expr); | |
5134 | SET_BIT (inserted[e], j); | |
5135 | did_insert = 1; | |
5136 | gcse_create_count++; | |
5137 | } | |
5138 | } | |
5139 | } | |
5140 | } | |
5141 | } | |
5142 | ||
5143 | sbitmap_vector_free (inserted); | |
5144 | return did_insert; | |
5145 | } | |
5146 | ||
5147 | /* Copy the result of INSN to REG. INDX is the expression number. */ | |
5148 | ||
5149 | static void | |
5150 | pre_insert_copy_insn (expr, insn) | |
5151 | struct expr *expr; | |
5152 | rtx insn; | |
5153 | { | |
5154 | rtx reg = expr->reaching_reg; | |
5155 | int regno = REGNO (reg); | |
5156 | int indx = expr->bitmap_index; | |
5157 | rtx set = single_set (insn); | |
5158 | rtx new_insn; | |
5159 | ||
5160 | if (!set) | |
5161 | abort (); | |
5162 | ||
5163 | new_insn = emit_insn_after (gen_move_insn (reg, SET_DEST (set)), insn); | |
5164 | ||
5165 | /* Keep register set table up to date. */ | |
5166 | record_one_set (regno, new_insn); | |
5167 | ||
5168 | gcse_create_count++; | |
5169 | ||
5170 | if (gcse_file) | |
5171 | fprintf (gcse_file, | |
5172 | "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n", | |
5173 | BLOCK_NUM (insn), INSN_UID (new_insn), indx, | |
5174 | INSN_UID (insn), regno); | |
5175 | update_ld_motion_stores (expr); | |
5176 | } | |
5177 | ||
5178 | /* Copy available expressions that reach the redundant expression | |
5179 | to `reaching_reg'. */ | |
5180 | ||
5181 | static void | |
5182 | pre_insert_copies () | |
5183 | { | |
5184 | unsigned int i; | |
5185 | struct expr *expr; | |
5186 | struct occr *occr; | |
5187 | struct occr *avail; | |
5188 | ||
5189 | /* For each available expression in the table, copy the result to | |
5190 | `reaching_reg' if the expression reaches a deleted one. | |
5191 | ||
5192 | ??? The current algorithm is rather brute force. | |
5193 | Need to do some profiling. */ | |
5194 | ||
5195 | for (i = 0; i < expr_hash_table_size; i++) | |
5196 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
5197 | { | |
5198 | /* If the basic block isn't reachable, PPOUT will be TRUE. However, | |
5199 | we don't want to insert a copy here because the expression may not | |
5200 | really be redundant. So only insert an insn if the expression was | |
5201 | deleted. This test also avoids further processing if the | |
5202 | expression wasn't deleted anywhere. */ | |
5203 | if (expr->reaching_reg == NULL) | |
5204 | continue; | |
5205 | ||
5206 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
5207 | { | |
5208 | if (! occr->deleted_p) | |
5209 | continue; | |
5210 | ||
5211 | for (avail = expr->avail_occr; avail != NULL; avail = avail->next) | |
5212 | { | |
5213 | rtx insn = avail->insn; | |
5214 | ||
5215 | /* No need to handle this one if handled already. */ | |
5216 | if (avail->copied_p) | |
5217 | continue; | |
5218 | ||
5219 | /* Don't handle this one if it's a redundant one. */ | |
5220 | if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn))) | |
5221 | continue; | |
5222 | ||
5223 | /* Or if the expression doesn't reach the deleted one. */ | |
5224 | if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn), | |
5225 | expr, | |
5226 | BLOCK_FOR_INSN (occr->insn))) | |
5227 | continue; | |
5228 | ||
5229 | /* Copy the result of avail to reaching_reg. */ | |
5230 | pre_insert_copy_insn (expr, insn); | |
5231 | avail->copied_p = 1; | |
5232 | } | |
5233 | } | |
5234 | } | |
5235 | } | |
5236 | ||
5237 | /* Emit move from SRC to DEST noting the equivalence with expression computed | |
5238 | in INSN. */ | |
5239 | static rtx | |
5240 | gcse_emit_move_after (src, dest, insn) | |
5241 | rtx src, dest, insn; | |
5242 | { | |
5243 | rtx new; | |
5244 | rtx set = single_set (insn), set2; | |
5245 | rtx note; | |
5246 | rtx eqv; | |
5247 | ||
5248 | /* This should never fail since we're creating a reg->reg copy | |
5249 | we've verified to be valid. */ | |
5250 | ||
5251 | new = emit_insn_after (gen_move_insn (dest, src), insn); | |
5252 | ||
5253 | /* Note the equivalence for local CSE pass. */ | |
5254 | set2 = single_set (new); | |
5255 | if (!set2 || !rtx_equal_p (SET_DEST (set2), dest)) | |
5256 | return new; | |
5257 | if ((note = find_reg_equal_equiv_note (insn))) | |
5258 | eqv = XEXP (note, 0); | |
5259 | else | |
5260 | eqv = SET_SRC (set); | |
5261 | ||
5262 | set_unique_reg_note (new, REG_EQUAL, copy_insn_1 (src)); | |
5263 | ||
5264 | return new; | |
5265 | } | |
5266 | ||
5267 | /* Delete redundant computations. | |
5268 | Deletion is done by changing the insn to copy the `reaching_reg' of | |
5269 | the expression into the result of the SET. It is left to later passes | |
5270 | (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it. | |
5271 | ||
5272 | Returns non-zero if a change is made. */ | |
5273 | ||
5274 | static int | |
5275 | pre_delete () | |
5276 | { | |
5277 | unsigned int i; | |
5278 | int changed; | |
5279 | struct expr *expr; | |
5280 | struct occr *occr; | |
5281 | ||
5282 | changed = 0; | |
5283 | for (i = 0; i < expr_hash_table_size; i++) | |
5284 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
5285 | { | |
5286 | int indx = expr->bitmap_index; | |
5287 | ||
5288 | /* We only need to search antic_occr since we require | |
5289 | ANTLOC != 0. */ | |
5290 | ||
5291 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
5292 | { | |
5293 | rtx insn = occr->insn; | |
5294 | rtx set; | |
5295 | basic_block bb = BLOCK_FOR_INSN (insn); | |
5296 | ||
5297 | if (TEST_BIT (pre_delete_map[bb->index], indx)) | |
5298 | { | |
5299 | set = single_set (insn); | |
5300 | if (! set) | |
5301 | abort (); | |
5302 | ||
5303 | /* Create a pseudo-reg to store the result of reaching | |
5304 | expressions into. Get the mode for the new pseudo from | |
5305 | the mode of the original destination pseudo. */ | |
5306 | if (expr->reaching_reg == NULL) | |
5307 | expr->reaching_reg | |
5308 | = gen_reg_rtx (GET_MODE (SET_DEST (set))); | |
5309 | ||
5310 | gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn); | |
5311 | delete_insn (insn); | |
5312 | occr->deleted_p = 1; | |
5313 | SET_BIT (pre_redundant_insns, INSN_CUID (insn)); | |
5314 | changed = 1; | |
5315 | gcse_subst_count++; | |
5316 | ||
5317 | if (gcse_file) | |
5318 | { | |
5319 | fprintf (gcse_file, | |
5320 | "PRE: redundant insn %d (expression %d) in ", | |
5321 | INSN_UID (insn), indx); | |
5322 | fprintf (gcse_file, "bb %d, reaching reg is %d\n", | |
5323 | bb->index, REGNO (expr->reaching_reg)); | |
5324 | } | |
5325 | } | |
5326 | } | |
5327 | } | |
5328 | ||
5329 | return changed; | |
5330 | } | |
5331 | ||
5332 | /* Perform GCSE optimizations using PRE. | |
5333 | This is called by one_pre_gcse_pass after all the dataflow analysis | |
5334 | has been done. | |
5335 | ||
5336 | This is based on the original Morel-Renvoise paper Fred Chow's thesis, and | |
5337 | lazy code motion from Knoop, Ruthing and Steffen as described in Advanced | |
5338 | Compiler Design and Implementation. | |
5339 | ||
5340 | ??? A new pseudo reg is created to hold the reaching expression. The nice | |
5341 | thing about the classical approach is that it would try to use an existing | |
5342 | reg. If the register can't be adequately optimized [i.e. we introduce | |
5343 | reload problems], one could add a pass here to propagate the new register | |
5344 | through the block. | |
5345 | ||
5346 | ??? We don't handle single sets in PARALLELs because we're [currently] not | |
5347 | able to copy the rest of the parallel when we insert copies to create full | |
5348 | redundancies from partial redundancies. However, there's no reason why we | |
5349 | can't handle PARALLELs in the cases where there are no partial | |
5350 | redundancies. */ | |
5351 | ||
5352 | static int | |
5353 | pre_gcse () | |
5354 | { | |
5355 | unsigned int i; | |
5356 | int did_insert, changed; | |
5357 | struct expr **index_map; | |
5358 | struct expr *expr; | |
5359 | ||
5360 | /* Compute a mapping from expression number (`bitmap_index') to | |
5361 | hash table entry. */ | |
5362 | ||
5363 | index_map = (struct expr **) xcalloc (n_exprs, sizeof (struct expr *)); | |
5364 | for (i = 0; i < expr_hash_table_size; i++) | |
5365 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
5366 | index_map[expr->bitmap_index] = expr; | |
5367 | ||
5368 | /* Reset bitmap used to track which insns are redundant. */ | |
5369 | pre_redundant_insns = sbitmap_alloc (max_cuid); | |
5370 | sbitmap_zero (pre_redundant_insns); | |
5371 | ||
5372 | /* Delete the redundant insns first so that | |
5373 | - we know what register to use for the new insns and for the other | |
5374 | ones with reaching expressions | |
5375 | - we know which insns are redundant when we go to create copies */ | |
5376 | ||
5377 | changed = pre_delete (); | |
5378 | ||
5379 | did_insert = pre_edge_insert (edge_list, index_map); | |
5380 | ||
5381 | /* In other places with reaching expressions, copy the expression to the | |
5382 | specially allocated pseudo-reg that reaches the redundant expr. */ | |
5383 | pre_insert_copies (); | |
5384 | if (did_insert) | |
5385 | { | |
5386 | commit_edge_insertions (); | |
5387 | changed = 1; | |
5388 | } | |
5389 | ||
5390 | free (index_map); | |
5391 | sbitmap_free (pre_redundant_insns); | |
5392 | return changed; | |
5393 | } | |
5394 | ||
5395 | /* Top level routine to perform one PRE GCSE pass. | |
5396 | ||
5397 | Return non-zero if a change was made. */ | |
5398 | ||
5399 | static int | |
5400 | one_pre_gcse_pass (pass) | |
5401 | int pass; | |
5402 | { | |
5403 | int changed = 0; | |
5404 | ||
5405 | gcse_subst_count = 0; | |
5406 | gcse_create_count = 0; | |
5407 | ||
5408 | alloc_expr_hash_table (max_cuid); | |
5409 | add_noreturn_fake_exit_edges (); | |
5410 | if (flag_gcse_lm) | |
5411 | compute_ld_motion_mems (); | |
5412 | ||
5413 | compute_expr_hash_table (); | |
5414 | trim_ld_motion_mems (); | |
5415 | if (gcse_file) | |
5416 | dump_hash_table (gcse_file, "Expression", expr_hash_table, | |
5417 | expr_hash_table_size, n_exprs); | |
5418 | ||
5419 | if (n_exprs > 0) | |
5420 | { | |
5421 | alloc_pre_mem (last_basic_block, n_exprs); | |
5422 | compute_pre_data (); | |
5423 | changed |= pre_gcse (); | |
5424 | free_edge_list (edge_list); | |
5425 | free_pre_mem (); | |
5426 | } | |
5427 | ||
5428 | free_ldst_mems (); | |
5429 | remove_fake_edges (); | |
5430 | free_expr_hash_table (); | |
5431 | ||
5432 | if (gcse_file) | |
5433 | { | |
5434 | fprintf (gcse_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ", | |
5435 | current_function_name, pass, bytes_used); | |
5436 | fprintf (gcse_file, "%d substs, %d insns created\n", | |
5437 | gcse_subst_count, gcse_create_count); | |
5438 | } | |
5439 | ||
5440 | return changed; | |
5441 | } | |
5442 | \f | |
5443 | /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN. | |
5444 | If notes are added to an insn which references a CODE_LABEL, the | |
5445 | LABEL_NUSES count is incremented. We have to add REG_LABEL notes, | |
5446 | because the following loop optimization pass requires them. */ | |
5447 | ||
5448 | /* ??? This is very similar to the loop.c add_label_notes function. We | |
5449 | could probably share code here. */ | |
5450 | ||
5451 | /* ??? If there was a jump optimization pass after gcse and before loop, | |
5452 | then we would not need to do this here, because jump would add the | |
5453 | necessary REG_LABEL notes. */ | |
5454 | ||
5455 | static void | |
5456 | add_label_notes (x, insn) | |
5457 | rtx x; | |
5458 | rtx insn; | |
5459 | { | |
5460 | enum rtx_code code = GET_CODE (x); | |
5461 | int i, j; | |
5462 | const char *fmt; | |
5463 | ||
5464 | if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x)) | |
5465 | { | |
5466 | /* This code used to ignore labels that referred to dispatch tables to | |
5467 | avoid flow generating (slighly) worse code. | |
5468 | ||
5469 | We no longer ignore such label references (see LABEL_REF handling in | |
5470 | mark_jump_label for additional information). */ | |
5471 | ||
5472 | REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, XEXP (x, 0), | |
5473 | REG_NOTES (insn)); | |
5474 | if (LABEL_P (XEXP (x, 0))) | |
5475 | LABEL_NUSES (XEXP (x, 0))++; | |
5476 | return; | |
5477 | } | |
5478 | ||
5479 | for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--) | |
5480 | { | |
5481 | if (fmt[i] == 'e') | |
5482 | add_label_notes (XEXP (x, i), insn); | |
5483 | else if (fmt[i] == 'E') | |
5484 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
5485 | add_label_notes (XVECEXP (x, i, j), insn); | |
5486 | } | |
5487 | } | |
5488 | ||
5489 | /* Compute transparent outgoing information for each block. | |
5490 | ||
5491 | An expression is transparent to an edge unless it is killed by | |
5492 | the edge itself. This can only happen with abnormal control flow, | |
5493 | when the edge is traversed through a call. This happens with | |
5494 | non-local labels and exceptions. | |
5495 | ||
5496 | This would not be necessary if we split the edge. While this is | |
5497 | normally impossible for abnormal critical edges, with some effort | |
5498 | it should be possible with exception handling, since we still have | |
5499 | control over which handler should be invoked. But due to increased | |
5500 | EH table sizes, this may not be worthwhile. */ | |
5501 | ||
5502 | static void | |
5503 | compute_transpout () | |
5504 | { | |
5505 | basic_block bb; | |
5506 | unsigned int i; | |
5507 | struct expr *expr; | |
5508 | ||
5509 | sbitmap_vector_ones (transpout, last_basic_block); | |
5510 | ||
5511 | FOR_EACH_BB (bb) | |
5512 | { | |
5513 | /* Note that flow inserted a nop a the end of basic blocks that | |
5514 | end in call instructions for reasons other than abnormal | |
5515 | control flow. */ | |
5516 | if (GET_CODE (bb->end) != CALL_INSN) | |
5517 | continue; | |
5518 | ||
5519 | for (i = 0; i < expr_hash_table_size; i++) | |
5520 | for (expr = expr_hash_table[i]; expr ; expr = expr->next_same_hash) | |
5521 | if (GET_CODE (expr->expr) == MEM) | |
5522 | { | |
5523 | if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF | |
5524 | && CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0))) | |
5525 | continue; | |
5526 | ||
5527 | /* ??? Optimally, we would use interprocedural alias | |
5528 | analysis to determine if this mem is actually killed | |
5529 | by this call. */ | |
5530 | RESET_BIT (transpout[bb->index], expr->bitmap_index); | |
5531 | } | |
5532 | } | |
5533 | } | |
5534 | ||
5535 | /* Removal of useless null pointer checks */ | |
5536 | ||
5537 | /* Called via note_stores. X is set by SETTER. If X is a register we must | |
5538 | invalidate nonnull_local and set nonnull_killed. DATA is really a | |
5539 | `null_pointer_info *'. | |
5540 | ||
5541 | We ignore hard registers. */ | |
5542 | ||
5543 | static void | |
5544 | invalidate_nonnull_info (x, setter, data) | |
5545 | rtx x; | |
5546 | rtx setter ATTRIBUTE_UNUSED; | |
5547 | void *data; | |
5548 | { | |
5549 | unsigned int regno; | |
5550 | struct null_pointer_info *npi = (struct null_pointer_info *) data; | |
5551 | ||
5552 | while (GET_CODE (x) == SUBREG) | |
5553 | x = SUBREG_REG (x); | |
5554 | ||
5555 | /* Ignore anything that is not a register or is a hard register. */ | |
5556 | if (GET_CODE (x) != REG | |
5557 | || REGNO (x) < npi->min_reg | |
5558 | || REGNO (x) >= npi->max_reg) | |
5559 | return; | |
5560 | ||
5561 | regno = REGNO (x) - npi->min_reg; | |
5562 | ||
5563 | RESET_BIT (npi->nonnull_local[npi->current_block->index], regno); | |
5564 | SET_BIT (npi->nonnull_killed[npi->current_block->index], regno); | |
5565 | } | |
5566 | ||
5567 | /* Do null-pointer check elimination for the registers indicated in | |
5568 | NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps; | |
5569 | they are not our responsibility to free. */ | |
5570 | ||
5571 | static int | |
5572 | delete_null_pointer_checks_1 (block_reg, nonnull_avin, | |
5573 | nonnull_avout, npi) | |
5574 | unsigned int *block_reg; | |
5575 | sbitmap *nonnull_avin; | |
5576 | sbitmap *nonnull_avout; | |
5577 | struct null_pointer_info *npi; | |
5578 | { | |
5579 | basic_block bb, current_block; | |
5580 | sbitmap *nonnull_local = npi->nonnull_local; | |
5581 | sbitmap *nonnull_killed = npi->nonnull_killed; | |
5582 | int something_changed = 0; | |
5583 | ||
5584 | /* Compute local properties, nonnull and killed. A register will have | |
5585 | the nonnull property if at the end of the current block its value is | |
5586 | known to be nonnull. The killed property indicates that somewhere in | |
5587 | the block any information we had about the register is killed. | |
5588 | ||
5589 | Note that a register can have both properties in a single block. That | |
5590 | indicates that it's killed, then later in the block a new value is | |
5591 | computed. */ | |
5592 | sbitmap_vector_zero (nonnull_local, last_basic_block); | |
5593 | sbitmap_vector_zero (nonnull_killed, last_basic_block); | |
5594 | ||
5595 | FOR_EACH_BB (current_block) | |
5596 | { | |
5597 | rtx insn, stop_insn; | |
5598 | ||
5599 | /* Set the current block for invalidate_nonnull_info. */ | |
5600 | npi->current_block = current_block; | |
5601 | ||
5602 | /* Scan each insn in the basic block looking for memory references and | |
5603 | register sets. */ | |
5604 | stop_insn = NEXT_INSN (current_block->end); | |
5605 | for (insn = current_block->head; | |
5606 | insn != stop_insn; | |
5607 | insn = NEXT_INSN (insn)) | |
5608 | { | |
5609 | rtx set; | |
5610 | rtx reg; | |
5611 | ||
5612 | /* Ignore anything that is not a normal insn. */ | |
5613 | if (! INSN_P (insn)) | |
5614 | continue; | |
5615 | ||
5616 | /* Basically ignore anything that is not a simple SET. We do have | |
5617 | to make sure to invalidate nonnull_local and set nonnull_killed | |
5618 | for such insns though. */ | |
5619 | set = single_set (insn); | |
5620 | if (!set) | |
5621 | { | |
5622 | note_stores (PATTERN (insn), invalidate_nonnull_info, npi); | |
5623 | continue; | |
5624 | } | |
5625 | ||
5626 | /* See if we've got a usable memory load. We handle it first | |
5627 | in case it uses its address register as a dest (which kills | |
5628 | the nonnull property). */ | |
5629 | if (GET_CODE (SET_SRC (set)) == MEM | |
5630 | && GET_CODE ((reg = XEXP (SET_SRC (set), 0))) == REG | |
5631 | && REGNO (reg) >= npi->min_reg | |
5632 | && REGNO (reg) < npi->max_reg) | |
5633 | SET_BIT (nonnull_local[current_block->index], | |
5634 | REGNO (reg) - npi->min_reg); | |
5635 | ||
5636 | /* Now invalidate stuff clobbered by this insn. */ | |
5637 | note_stores (PATTERN (insn), invalidate_nonnull_info, npi); | |
5638 | ||
5639 | /* And handle stores, we do these last since any sets in INSN can | |
5640 | not kill the nonnull property if it is derived from a MEM | |
5641 | appearing in a SET_DEST. */ | |
5642 | if (GET_CODE (SET_DEST (set)) == MEM | |
5643 | && GET_CODE ((reg = XEXP (SET_DEST (set), 0))) == REG | |
5644 | && REGNO (reg) >= npi->min_reg | |
5645 | && REGNO (reg) < npi->max_reg) | |
5646 | SET_BIT (nonnull_local[current_block->index], | |
5647 | REGNO (reg) - npi->min_reg); | |
5648 | } | |
5649 | } | |
5650 | ||
5651 | /* Now compute global properties based on the local properties. This | |
5652 | is a classic global availablity algorithm. */ | |
5653 | compute_available (nonnull_local, nonnull_killed, | |
5654 | nonnull_avout, nonnull_avin); | |
5655 | ||
5656 | /* Now look at each bb and see if it ends with a compare of a value | |
5657 | against zero. */ | |
5658 | FOR_EACH_BB (bb) | |
5659 | { | |
5660 | rtx last_insn = bb->end; | |
5661 | rtx condition, earliest; | |
5662 | int compare_and_branch; | |
5663 | ||
5664 | /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and | |
5665 | since BLOCK_REG[BB] is zero if this block did not end with a | |
5666 | comparison against zero, this condition works. */ | |
5667 | if (block_reg[bb->index] < npi->min_reg | |
5668 | || block_reg[bb->index] >= npi->max_reg) | |
5669 | continue; | |
5670 | ||
5671 | /* LAST_INSN is a conditional jump. Get its condition. */ | |
5672 | condition = get_condition (last_insn, &earliest); | |
5673 | ||
5674 | /* If we can't determine the condition then skip. */ | |
5675 | if (! condition) | |
5676 | continue; | |
5677 | ||
5678 | /* Is the register known to have a nonzero value? */ | |
5679 | if (!TEST_BIT (nonnull_avout[bb->index], block_reg[bb->index] - npi->min_reg)) | |
5680 | continue; | |
5681 | ||
5682 | /* Try to compute whether the compare/branch at the loop end is one or | |
5683 | two instructions. */ | |
5684 | if (earliest == last_insn) | |
5685 | compare_and_branch = 1; | |
5686 | else if (earliest == prev_nonnote_insn (last_insn)) | |
5687 | compare_and_branch = 2; | |
5688 | else | |
5689 | continue; | |
5690 | ||
5691 | /* We know the register in this comparison is nonnull at exit from | |
5692 | this block. We can optimize this comparison. */ | |
5693 | if (GET_CODE (condition) == NE) | |
5694 | { | |
5695 | rtx new_jump; | |
5696 | ||
5697 | new_jump = emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn)), | |
5698 | last_insn); | |
5699 | JUMP_LABEL (new_jump) = JUMP_LABEL (last_insn); | |
5700 | LABEL_NUSES (JUMP_LABEL (new_jump))++; | |
5701 | emit_barrier_after (new_jump); | |
5702 | } | |
5703 | ||
5704 | something_changed = 1; | |
5705 | delete_insn (last_insn); | |
5706 | if (compare_and_branch == 2) | |
5707 | delete_insn (earliest); | |
5708 | purge_dead_edges (bb); | |
5709 | ||
5710 | /* Don't check this block again. (Note that BLOCK_END is | |
5711 | invalid here; we deleted the last instruction in the | |
5712 | block.) */ | |
5713 | block_reg[bb->index] = 0; | |
5714 | } | |
5715 | ||
5716 | return something_changed; | |
5717 | } | |
5718 | ||
5719 | /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated | |
5720 | at compile time. | |
5721 | ||
5722 | This is conceptually similar to global constant/copy propagation and | |
5723 | classic global CSE (it even uses the same dataflow equations as cprop). | |
5724 | ||
5725 | If a register is used as memory address with the form (mem (reg)), then we | |
5726 | know that REG can not be zero at that point in the program. Any instruction | |
5727 | which sets REG "kills" this property. | |
5728 | ||
5729 | So, if every path leading to a conditional branch has an available memory | |
5730 | reference of that form, then we know the register can not have the value | |
5731 | zero at the conditional branch. | |
5732 | ||
5733 | So we merely need to compute the local properies and propagate that data | |
5734 | around the cfg, then optimize where possible. | |
5735 | ||
5736 | We run this pass two times. Once before CSE, then again after CSE. This | |
5737 | has proven to be the most profitable approach. It is rare for new | |
5738 | optimization opportunities of this nature to appear after the first CSE | |
5739 | pass. | |
5740 | ||
5741 | This could probably be integrated with global cprop with a little work. */ | |
5742 | ||
5743 | int | |
5744 | delete_null_pointer_checks (f) | |
5745 | rtx f ATTRIBUTE_UNUSED; | |
5746 | { | |
5747 | sbitmap *nonnull_avin, *nonnull_avout; | |
5748 | unsigned int *block_reg; | |
5749 | basic_block bb; | |
5750 | int reg; | |
5751 | int regs_per_pass; | |
5752 | int max_reg; | |
5753 | struct null_pointer_info npi; | |
5754 | int something_changed = 0; | |
5755 | ||
5756 | /* If we have only a single block, then there's nothing to do. */ | |
5757 | if (n_basic_blocks <= 1) | |
5758 | return 0; | |
5759 | ||
5760 | /* Trying to perform global optimizations on flow graphs which have | |
5761 | a high connectivity will take a long time and is unlikely to be | |
5762 | particularly useful. | |
5763 | ||
5764 | In normal circumstances a cfg should have about twice as many edges | |
5765 | as blocks. But we do not want to punish small functions which have | |
5766 | a couple switch statements. So we require a relatively large number | |
5767 | of basic blocks and the ratio of edges to blocks to be high. */ | |
5768 | if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20) | |
5769 | return 0; | |
5770 | ||
5771 | /* We need four bitmaps, each with a bit for each register in each | |
5772 | basic block. */ | |
5773 | max_reg = max_reg_num (); | |
5774 | regs_per_pass = get_bitmap_width (4, last_basic_block, max_reg); | |
5775 | ||
5776 | /* Allocate bitmaps to hold local and global properties. */ | |
5777 | npi.nonnull_local = sbitmap_vector_alloc (last_basic_block, regs_per_pass); | |
5778 | npi.nonnull_killed = sbitmap_vector_alloc (last_basic_block, regs_per_pass); | |
5779 | nonnull_avin = sbitmap_vector_alloc (last_basic_block, regs_per_pass); | |
5780 | nonnull_avout = sbitmap_vector_alloc (last_basic_block, regs_per_pass); | |
5781 | ||
5782 | /* Go through the basic blocks, seeing whether or not each block | |
5783 | ends with a conditional branch whose condition is a comparison | |
5784 | against zero. Record the register compared in BLOCK_REG. */ | |
5785 | block_reg = (unsigned int *) xcalloc (last_basic_block, sizeof (int)); | |
5786 | FOR_EACH_BB (bb) | |
5787 | { | |
5788 | rtx last_insn = bb->end; | |
5789 | rtx condition, earliest, reg; | |
5790 | ||
5791 | /* We only want conditional branches. */ | |
5792 | if (GET_CODE (last_insn) != JUMP_INSN | |
5793 | || !any_condjump_p (last_insn) | |
5794 | || !onlyjump_p (last_insn)) | |
5795 | continue; | |
5796 | ||
5797 | /* LAST_INSN is a conditional jump. Get its condition. */ | |
5798 | condition = get_condition (last_insn, &earliest); | |
5799 | ||
5800 | /* If we were unable to get the condition, or it is not an equality | |
5801 | comparison against zero then there's nothing we can do. */ | |
5802 | if (!condition | |
5803 | || (GET_CODE (condition) != NE && GET_CODE (condition) != EQ) | |
5804 | || GET_CODE (XEXP (condition, 1)) != CONST_INT | |
5805 | || (XEXP (condition, 1) | |
5806 | != CONST0_RTX (GET_MODE (XEXP (condition, 0))))) | |
5807 | continue; | |
5808 | ||
5809 | /* We must be checking a register against zero. */ | |
5810 | reg = XEXP (condition, 0); | |
5811 | if (GET_CODE (reg) != REG) | |
5812 | continue; | |
5813 | ||
5814 | block_reg[bb->index] = REGNO (reg); | |
5815 | } | |
5816 | ||
5817 | /* Go through the algorithm for each block of registers. */ | |
5818 | for (reg = FIRST_PSEUDO_REGISTER; reg < max_reg; reg += regs_per_pass) | |
5819 | { | |
5820 | npi.min_reg = reg; | |
5821 | npi.max_reg = MIN (reg + regs_per_pass, max_reg); | |
5822 | something_changed |= delete_null_pointer_checks_1 (block_reg, | |
5823 | nonnull_avin, | |
5824 | nonnull_avout, | |
5825 | &npi); | |
5826 | } | |
5827 | ||
5828 | /* Free the table of registers compared at the end of every block. */ | |
5829 | free (block_reg); | |
5830 | ||
5831 | /* Free bitmaps. */ | |
5832 | sbitmap_vector_free (npi.nonnull_local); | |
5833 | sbitmap_vector_free (npi.nonnull_killed); | |
5834 | sbitmap_vector_free (nonnull_avin); | |
5835 | sbitmap_vector_free (nonnull_avout); | |
5836 | ||
5837 | return something_changed; | |
5838 | } | |
5839 | ||
5840 | /* Code Hoisting variables and subroutines. */ | |
5841 | ||
5842 | /* Very busy expressions. */ | |
5843 | static sbitmap *hoist_vbein; | |
5844 | static sbitmap *hoist_vbeout; | |
5845 | ||
5846 | /* Hoistable expressions. */ | |
5847 | static sbitmap *hoist_exprs; | |
5848 | ||
5849 | /* Dominator bitmaps. */ | |
5850 | dominance_info dominators; | |
5851 | ||
5852 | /* ??? We could compute post dominators and run this algorithm in | |
5853 | reverse to perform tail merging, doing so would probably be | |
5854 | more effective than the tail merging code in jump.c. | |
5855 | ||
5856 | It's unclear if tail merging could be run in parallel with | |
5857 | code hoisting. It would be nice. */ | |
5858 | ||
5859 | /* Allocate vars used for code hoisting analysis. */ | |
5860 | ||
5861 | static void | |
5862 | alloc_code_hoist_mem (n_blocks, n_exprs) | |
5863 | int n_blocks, n_exprs; | |
5864 | { | |
5865 | antloc = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5866 | transp = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5867 | comp = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5868 | ||
5869 | hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5870 | hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5871 | hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5872 | transpout = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5873 | } | |
5874 | ||
5875 | /* Free vars used for code hoisting analysis. */ | |
5876 | ||
5877 | static void | |
5878 | free_code_hoist_mem () | |
5879 | { | |
5880 | sbitmap_vector_free (antloc); | |
5881 | sbitmap_vector_free (transp); | |
5882 | sbitmap_vector_free (comp); | |
5883 | ||
5884 | sbitmap_vector_free (hoist_vbein); | |
5885 | sbitmap_vector_free (hoist_vbeout); | |
5886 | sbitmap_vector_free (hoist_exprs); | |
5887 | sbitmap_vector_free (transpout); | |
5888 | ||
5889 | free_dominance_info (dominators); | |
5890 | } | |
5891 | ||
5892 | /* Compute the very busy expressions at entry/exit from each block. | |
5893 | ||
5894 | An expression is very busy if all paths from a given point | |
5895 | compute the expression. */ | |
5896 | ||
5897 | static void | |
5898 | compute_code_hoist_vbeinout () | |
5899 | { | |
5900 | int changed, passes; | |
5901 | basic_block bb; | |
5902 | ||
5903 | sbitmap_vector_zero (hoist_vbeout, last_basic_block); | |
5904 | sbitmap_vector_zero (hoist_vbein, last_basic_block); | |
5905 | ||
5906 | passes = 0; | |
5907 | changed = 1; | |
5908 | ||
5909 | while (changed) | |
5910 | { | |
5911 | changed = 0; | |
5912 | ||
5913 | /* We scan the blocks in the reverse order to speed up | |
5914 | the convergence. */ | |
5915 | FOR_EACH_BB_REVERSE (bb) | |
5916 | { | |
5917 | changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index], antloc[bb->index], | |
5918 | hoist_vbeout[bb->index], transp[bb->index]); | |
5919 | if (bb->next_bb != EXIT_BLOCK_PTR) | |
5920 | sbitmap_intersection_of_succs (hoist_vbeout[bb->index], hoist_vbein, bb->index); | |
5921 | } | |
5922 | ||
5923 | passes++; | |
5924 | } | |
5925 | ||
5926 | if (gcse_file) | |
5927 | fprintf (gcse_file, "hoisting vbeinout computation: %d passes\n", passes); | |
5928 | } | |
5929 | ||
5930 | /* Top level routine to do the dataflow analysis needed by code hoisting. */ | |
5931 | ||
5932 | static void | |
5933 | compute_code_hoist_data () | |
5934 | { | |
5935 | compute_local_properties (transp, comp, antloc, 0); | |
5936 | compute_transpout (); | |
5937 | compute_code_hoist_vbeinout (); | |
5938 | dominators = calculate_dominance_info (CDI_DOMINATORS); | |
5939 | if (gcse_file) | |
5940 | fprintf (gcse_file, "\n"); | |
5941 | } | |
5942 | ||
5943 | /* Determine if the expression identified by EXPR_INDEX would | |
5944 | reach BB unimpared if it was placed at the end of EXPR_BB. | |
5945 | ||
5946 | It's unclear exactly what Muchnick meant by "unimpared". It seems | |
5947 | to me that the expression must either be computed or transparent in | |
5948 | *every* block in the path(s) from EXPR_BB to BB. Any other definition | |
5949 | would allow the expression to be hoisted out of loops, even if | |
5950 | the expression wasn't a loop invariant. | |
5951 | ||
5952 | Contrast this to reachability for PRE where an expression is | |
5953 | considered reachable if *any* path reaches instead of *all* | |
5954 | paths. */ | |
5955 | ||
5956 | static int | |
5957 | hoist_expr_reaches_here_p (expr_bb, expr_index, bb, visited) | |
5958 | basic_block expr_bb; | |
5959 | int expr_index; | |
5960 | basic_block bb; | |
5961 | char *visited; | |
5962 | { | |
5963 | edge pred; | |
5964 | int visited_allocated_locally = 0; | |
5965 | ||
5966 | ||
5967 | if (visited == NULL) | |
5968 | { | |
5969 | visited_allocated_locally = 1; | |
5970 | visited = xcalloc (last_basic_block, 1); | |
5971 | } | |
5972 | ||
5973 | for (pred = bb->pred; pred != NULL; pred = pred->pred_next) | |
5974 | { | |
5975 | basic_block pred_bb = pred->src; | |
5976 | ||
5977 | if (pred->src == ENTRY_BLOCK_PTR) | |
5978 | break; | |
5979 | else if (pred_bb == expr_bb) | |
5980 | continue; | |
5981 | else if (visited[pred_bb->index]) | |
5982 | continue; | |
5983 | ||
5984 | /* Does this predecessor generate this expression? */ | |
5985 | else if (TEST_BIT (comp[pred_bb->index], expr_index)) | |
5986 | break; | |
5987 | else if (! TEST_BIT (transp[pred_bb->index], expr_index)) | |
5988 | break; | |
5989 | ||
5990 | /* Not killed. */ | |
5991 | else | |
5992 | { | |
5993 | visited[pred_bb->index] = 1; | |
5994 | if (! hoist_expr_reaches_here_p (expr_bb, expr_index, | |
5995 | pred_bb, visited)) | |
5996 | break; | |
5997 | } | |
5998 | } | |
5999 | if (visited_allocated_locally) | |
6000 | free (visited); | |
6001 | ||
6002 | return (pred == NULL); | |
6003 | } | |
6004 | \f | |
6005 | /* Actually perform code hoisting. */ | |
6006 | ||
6007 | static void | |
6008 | hoist_code () | |
6009 | { | |
6010 | basic_block bb, dominated; | |
6011 | basic_block *domby; | |
6012 | unsigned int domby_len; | |
6013 | unsigned int i,j; | |
6014 | struct expr **index_map; | |
6015 | struct expr *expr; | |
6016 | ||
6017 | sbitmap_vector_zero (hoist_exprs, last_basic_block); | |
6018 | ||
6019 | /* Compute a mapping from expression number (`bitmap_index') to | |
6020 | hash table entry. */ | |
6021 | ||
6022 | index_map = (struct expr **) xcalloc (n_exprs, sizeof (struct expr *)); | |
6023 | for (i = 0; i < expr_hash_table_size; i++) | |
6024 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
6025 | index_map[expr->bitmap_index] = expr; | |
6026 | ||
6027 | /* Walk over each basic block looking for potentially hoistable | |
6028 | expressions, nothing gets hoisted from the entry block. */ | |
6029 | FOR_EACH_BB (bb) | |
6030 | { | |
6031 | int found = 0; | |
6032 | int insn_inserted_p; | |
6033 | ||
6034 | domby_len = get_dominated_by (dominators, bb, &domby); | |
6035 | /* Examine each expression that is very busy at the exit of this | |
6036 | block. These are the potentially hoistable expressions. */ | |
6037 | for (i = 0; i < hoist_vbeout[bb->index]->n_bits; i++) | |
6038 | { | |
6039 | int hoistable = 0; | |
6040 | ||
6041 | if (TEST_BIT (hoist_vbeout[bb->index], i) | |
6042 | && TEST_BIT (transpout[bb->index], i)) | |
6043 | { | |
6044 | /* We've found a potentially hoistable expression, now | |
6045 | we look at every block BB dominates to see if it | |
6046 | computes the expression. */ | |
6047 | for (j = 0; j < domby_len; j++) | |
6048 | { | |
6049 | dominated = domby[j]; | |
6050 | /* Ignore self dominance. */ | |
6051 | if (bb == dominated) | |
6052 | continue; | |
6053 | /* We've found a dominated block, now see if it computes | |
6054 | the busy expression and whether or not moving that | |
6055 | expression to the "beginning" of that block is safe. */ | |
6056 | if (!TEST_BIT (antloc[dominated->index], i)) | |
6057 | continue; | |
6058 | ||
6059 | /* Note if the expression would reach the dominated block | |
6060 | unimpared if it was placed at the end of BB. | |
6061 | ||
6062 | Keep track of how many times this expression is hoistable | |
6063 | from a dominated block into BB. */ | |
6064 | if (hoist_expr_reaches_here_p (bb, i, dominated, NULL)) | |
6065 | hoistable++; | |
6066 | } | |
6067 | ||
6068 | /* If we found more than one hoistable occurrence of this | |
6069 | expression, then note it in the bitmap of expressions to | |
6070 | hoist. It makes no sense to hoist things which are computed | |
6071 | in only one BB, and doing so tends to pessimize register | |
6072 | allocation. One could increase this value to try harder | |
6073 | to avoid any possible code expansion due to register | |
6074 | allocation issues; however experiments have shown that | |
6075 | the vast majority of hoistable expressions are only movable | |
6076 | from two successors, so raising this threshhold is likely | |
6077 | to nullify any benefit we get from code hoisting. */ | |
6078 | if (hoistable > 1) | |
6079 | { | |
6080 | SET_BIT (hoist_exprs[bb->index], i); | |
6081 | found = 1; | |
6082 | } | |
6083 | } | |
6084 | } | |
6085 | /* If we found nothing to hoist, then quit now. */ | |
6086 | if (! found) | |
6087 | { | |
6088 | free (domby); | |
6089 | continue; | |
6090 | } | |
6091 | ||
6092 | /* Loop over all the hoistable expressions. */ | |
6093 | for (i = 0; i < hoist_exprs[bb->index]->n_bits; i++) | |
6094 | { | |
6095 | /* We want to insert the expression into BB only once, so | |
6096 | note when we've inserted it. */ | |
6097 | insn_inserted_p = 0; | |
6098 | ||
6099 | /* These tests should be the same as the tests above. */ | |
6100 | if (TEST_BIT (hoist_vbeout[bb->index], i)) | |
6101 | { | |
6102 | /* We've found a potentially hoistable expression, now | |
6103 | we look at every block BB dominates to see if it | |
6104 | computes the expression. */ | |
6105 | for (j = 0; j < domby_len; j++) | |
6106 | { | |
6107 | dominated = domby[j]; | |
6108 | /* Ignore self dominance. */ | |
6109 | if (bb == dominated) | |
6110 | continue; | |
6111 | ||
6112 | /* We've found a dominated block, now see if it computes | |
6113 | the busy expression and whether or not moving that | |
6114 | expression to the "beginning" of that block is safe. */ | |
6115 | if (!TEST_BIT (antloc[dominated->index], i)) | |
6116 | continue; | |
6117 | ||
6118 | /* The expression is computed in the dominated block and | |
6119 | it would be safe to compute it at the start of the | |
6120 | dominated block. Now we have to determine if the | |
6121 | expression would reach the dominated block if it was | |
6122 | placed at the end of BB. */ | |
6123 | if (hoist_expr_reaches_here_p (bb, i, dominated, NULL)) | |
6124 | { | |
6125 | struct expr *expr = index_map[i]; | |
6126 | struct occr *occr = expr->antic_occr; | |
6127 | rtx insn; | |
6128 | rtx set; | |
6129 | ||
6130 | /* Find the right occurrence of this expression. */ | |
6131 | while (BLOCK_FOR_INSN (occr->insn) != dominated && occr) | |
6132 | occr = occr->next; | |
6133 | ||
6134 | /* Should never happen. */ | |
6135 | if (!occr) | |
6136 | abort (); | |
6137 | ||
6138 | insn = occr->insn; | |
6139 | ||
6140 | set = single_set (insn); | |
6141 | if (! set) | |
6142 | abort (); | |
6143 | ||
6144 | /* Create a pseudo-reg to store the result of reaching | |
6145 | expressions into. Get the mode for the new pseudo | |
6146 | from the mode of the original destination pseudo. */ | |
6147 | if (expr->reaching_reg == NULL) | |
6148 | expr->reaching_reg | |
6149 | = gen_reg_rtx (GET_MODE (SET_DEST (set))); | |
6150 | ||
6151 | gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn); | |
6152 | delete_insn (insn); | |
6153 | occr->deleted_p = 1; | |
6154 | if (!insn_inserted_p) | |
6155 | { | |
6156 | insert_insn_end_bb (index_map[i], bb, 0); | |
6157 | insn_inserted_p = 1; | |
6158 | } | |
6159 | } | |
6160 | } | |
6161 | } | |
6162 | } | |
6163 | free (domby); | |
6164 | } | |
6165 | ||
6166 | free (index_map); | |
6167 | } | |
6168 | ||
6169 | /* Top level routine to perform one code hoisting (aka unification) pass | |
6170 | ||
6171 | Return non-zero if a change was made. */ | |
6172 | ||
6173 | static int | |
6174 | one_code_hoisting_pass () | |
6175 | { | |
6176 | int changed = 0; | |
6177 | ||
6178 | alloc_expr_hash_table (max_cuid); | |
6179 | compute_expr_hash_table (); | |
6180 | if (gcse_file) | |
6181 | dump_hash_table (gcse_file, "Code Hosting Expressions", expr_hash_table, | |
6182 | expr_hash_table_size, n_exprs); | |
6183 | ||
6184 | if (n_exprs > 0) | |
6185 | { | |
6186 | alloc_code_hoist_mem (last_basic_block, n_exprs); | |
6187 | compute_code_hoist_data (); | |
6188 | hoist_code (); | |
6189 | free_code_hoist_mem (); | |
6190 | } | |
6191 | ||
6192 | free_expr_hash_table (); | |
6193 | ||
6194 | return changed; | |
6195 | } | |
6196 | \f | |
6197 | /* Here we provide the things required to do store motion towards | |
6198 | the exit. In order for this to be effective, gcse also needed to | |
6199 | be taught how to move a load when it is kill only by a store to itself. | |
6200 | ||
6201 | int i; | |
6202 | float a[10]; | |
6203 | ||
6204 | void foo(float scale) | |
6205 | { | |
6206 | for (i=0; i<10; i++) | |
6207 | a[i] *= scale; | |
6208 | } | |
6209 | ||
6210 | 'i' is both loaded and stored to in the loop. Normally, gcse cannot move | |
6211 | the load out since its live around the loop, and stored at the bottom | |
6212 | of the loop. | |
6213 | ||
6214 | The 'Load Motion' referred to and implemented in this file is | |
6215 | an enhancement to gcse which when using edge based lcm, recognizes | |
6216 | this situation and allows gcse to move the load out of the loop. | |
6217 | ||
6218 | Once gcse has hoisted the load, store motion can then push this | |
6219 | load towards the exit, and we end up with no loads or stores of 'i' | |
6220 | in the loop. */ | |
6221 | ||
6222 | /* This will search the ldst list for a matching expression. If it | |
6223 | doesn't find one, we create one and initialize it. */ | |
6224 | ||
6225 | static struct ls_expr * | |
6226 | ldst_entry (x) | |
6227 | rtx x; | |
6228 | { | |
6229 | struct ls_expr * ptr; | |
6230 | ||
6231 | for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr)) | |
6232 | if (expr_equiv_p (ptr->pattern, x)) | |
6233 | break; | |
6234 | ||
6235 | if (!ptr) | |
6236 | { | |
6237 | ptr = (struct ls_expr *) xmalloc (sizeof (struct ls_expr)); | |
6238 | ||
6239 | ptr->next = pre_ldst_mems; | |
6240 | ptr->expr = NULL; | |
6241 | ptr->pattern = x; | |
6242 | ptr->loads = NULL_RTX; | |
6243 | ptr->stores = NULL_RTX; | |
6244 | ptr->reaching_reg = NULL_RTX; | |
6245 | ptr->invalid = 0; | |
6246 | ptr->index = 0; | |
6247 | ptr->hash_index = 0; | |
6248 | pre_ldst_mems = ptr; | |
6249 | } | |
6250 | ||
6251 | return ptr; | |
6252 | } | |
6253 | ||
6254 | /* Free up an individual ldst entry. */ | |
6255 | ||
6256 | static void | |
6257 | free_ldst_entry (ptr) | |
6258 | struct ls_expr * ptr; | |
6259 | { | |
6260 | free_INSN_LIST_list (& ptr->loads); | |
6261 | free_INSN_LIST_list (& ptr->stores); | |
6262 | ||
6263 | free (ptr); | |
6264 | } | |
6265 | ||
6266 | /* Free up all memory associated with the ldst list. */ | |
6267 | ||
6268 | static void | |
6269 | free_ldst_mems () | |
6270 | { | |
6271 | while (pre_ldst_mems) | |
6272 | { | |
6273 | struct ls_expr * tmp = pre_ldst_mems; | |
6274 | ||
6275 | pre_ldst_mems = pre_ldst_mems->next; | |
6276 | ||
6277 | free_ldst_entry (tmp); | |
6278 | } | |
6279 | ||
6280 | pre_ldst_mems = NULL; | |
6281 | } | |
6282 | ||
6283 | /* Dump debugging info about the ldst list. */ | |
6284 | ||
6285 | static void | |
6286 | print_ldst_list (file) | |
6287 | FILE * file; | |
6288 | { | |
6289 | struct ls_expr * ptr; | |
6290 | ||
6291 | fprintf (file, "LDST list: \n"); | |
6292 | ||
6293 | for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr)) | |
6294 | { | |
6295 | fprintf (file, " Pattern (%3d): ", ptr->index); | |
6296 | ||
6297 | print_rtl (file, ptr->pattern); | |
6298 | ||
6299 | fprintf (file, "\n Loads : "); | |
6300 | ||
6301 | if (ptr->loads) | |
6302 | print_rtl (file, ptr->loads); | |
6303 | else | |
6304 | fprintf (file, "(nil)"); | |
6305 | ||
6306 | fprintf (file, "\n Stores : "); | |
6307 | ||
6308 | if (ptr->stores) | |
6309 | print_rtl (file, ptr->stores); | |
6310 | else | |
6311 | fprintf (file, "(nil)"); | |
6312 | ||
6313 | fprintf (file, "\n\n"); | |
6314 | } | |
6315 | ||
6316 | fprintf (file, "\n"); | |
6317 | } | |
6318 | ||
6319 | /* Returns 1 if X is in the list of ldst only expressions. */ | |
6320 | ||
6321 | static struct ls_expr * | |
6322 | find_rtx_in_ldst (x) | |
6323 | rtx x; | |
6324 | { | |
6325 | struct ls_expr * ptr; | |
6326 | ||
6327 | for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next) | |
6328 | if (expr_equiv_p (ptr->pattern, x) && ! ptr->invalid) | |
6329 | return ptr; | |
6330 | ||
6331 | return NULL; | |
6332 | } | |
6333 | ||
6334 | /* Assign each element of the list of mems a monotonically increasing value. */ | |
6335 | ||
6336 | static int | |
6337 | enumerate_ldsts () | |
6338 | { | |
6339 | struct ls_expr * ptr; | |
6340 | int n = 0; | |
6341 | ||
6342 | for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next) | |
6343 | ptr->index = n++; | |
6344 | ||
6345 | return n; | |
6346 | } | |
6347 | ||
6348 | /* Return first item in the list. */ | |
6349 | ||
6350 | static inline struct ls_expr * | |
6351 | first_ls_expr () | |
6352 | { | |
6353 | return pre_ldst_mems; | |
6354 | } | |
6355 | ||
6356 | /* Return the next item in ther list after the specified one. */ | |
6357 | ||
6358 | static inline struct ls_expr * | |
6359 | next_ls_expr (ptr) | |
6360 | struct ls_expr * ptr; | |
6361 | { | |
6362 | return ptr->next; | |
6363 | } | |
6364 | \f | |
6365 | /* Load Motion for loads which only kill themselves. */ | |
6366 | ||
6367 | /* Return true if x is a simple MEM operation, with no registers or | |
6368 | side effects. These are the types of loads we consider for the | |
6369 | ld_motion list, otherwise we let the usual aliasing take care of it. */ | |
6370 | ||
6371 | static int | |
6372 | simple_mem (x) | |
6373 | rtx x; | |
6374 | { | |
6375 | if (GET_CODE (x) != MEM) | |
6376 | return 0; | |
6377 | ||
6378 | if (MEM_VOLATILE_P (x)) | |
6379 | return 0; | |
6380 | ||
6381 | if (GET_MODE (x) == BLKmode) | |
6382 | return 0; | |
6383 | ||
6384 | if (!rtx_varies_p (XEXP (x, 0), 0)) | |
6385 | return 1; | |
6386 | ||
6387 | return 0; | |
6388 | } | |
6389 | ||
6390 | /* Make sure there isn't a buried reference in this pattern anywhere. | |
6391 | If there is, invalidate the entry for it since we're not capable | |
6392 | of fixing it up just yet.. We have to be sure we know about ALL | |
6393 | loads since the aliasing code will allow all entries in the | |
6394 | ld_motion list to not-alias itself. If we miss a load, we will get | |
6395 | the wrong value since gcse might common it and we won't know to | |
6396 | fix it up. */ | |
6397 | ||
6398 | static void | |
6399 | invalidate_any_buried_refs (x) | |
6400 | rtx x; | |
6401 | { | |
6402 | const char * fmt; | |
6403 | int i, j; | |
6404 | struct ls_expr * ptr; | |
6405 | ||
6406 | /* Invalidate it in the list. */ | |
6407 | if (GET_CODE (x) == MEM && simple_mem (x)) | |
6408 | { | |
6409 | ptr = ldst_entry (x); | |
6410 | ptr->invalid = 1; | |
6411 | } | |
6412 | ||
6413 | /* Recursively process the insn. */ | |
6414 | fmt = GET_RTX_FORMAT (GET_CODE (x)); | |
6415 | ||
6416 | for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--) | |
6417 | { | |
6418 | if (fmt[i] == 'e') | |
6419 | invalidate_any_buried_refs (XEXP (x, i)); | |
6420 | else if (fmt[i] == 'E') | |
6421 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
6422 | invalidate_any_buried_refs (XVECEXP (x, i, j)); | |
6423 | } | |
6424 | } | |
6425 | ||
6426 | /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple | |
6427 | being defined as MEM loads and stores to symbols, with no | |
6428 | side effects and no registers in the expression. If there are any | |
6429 | uses/defs which don't match this criteria, it is invalidated and | |
6430 | trimmed out later. */ | |
6431 | ||
6432 | static void | |
6433 | compute_ld_motion_mems () | |
6434 | { | |
6435 | struct ls_expr * ptr; | |
6436 | basic_block bb; | |
6437 | rtx insn; | |
6438 | ||
6439 | pre_ldst_mems = NULL; | |
6440 | ||
6441 | FOR_EACH_BB (bb) | |
6442 | { | |
6443 | for (insn = bb->head; | |
6444 | insn && insn != NEXT_INSN (bb->end); | |
6445 | insn = NEXT_INSN (insn)) | |
6446 | { | |
6447 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
6448 | { | |
6449 | if (GET_CODE (PATTERN (insn)) == SET) | |
6450 | { | |
6451 | rtx src = SET_SRC (PATTERN (insn)); | |
6452 | rtx dest = SET_DEST (PATTERN (insn)); | |
6453 | ||
6454 | /* Check for a simple LOAD... */ | |
6455 | if (GET_CODE (src) == MEM && simple_mem (src)) | |
6456 | { | |
6457 | ptr = ldst_entry (src); | |
6458 | if (GET_CODE (dest) == REG) | |
6459 | ptr->loads = alloc_INSN_LIST (insn, ptr->loads); | |
6460 | else | |
6461 | ptr->invalid = 1; | |
6462 | } | |
6463 | else | |
6464 | { | |
6465 | /* Make sure there isn't a buried load somewhere. */ | |
6466 | invalidate_any_buried_refs (src); | |
6467 | } | |
6468 | ||
6469 | /* Check for stores. Don't worry about aliased ones, they | |
6470 | will block any movement we might do later. We only care | |
6471 | about this exact pattern since those are the only | |
6472 | circumstance that we will ignore the aliasing info. */ | |
6473 | if (GET_CODE (dest) == MEM && simple_mem (dest)) | |
6474 | { | |
6475 | ptr = ldst_entry (dest); | |
6476 | ||
6477 | if (GET_CODE (src) != MEM | |
6478 | && GET_CODE (src) != ASM_OPERANDS) | |
6479 | ptr->stores = alloc_INSN_LIST (insn, ptr->stores); | |
6480 | else | |
6481 | ptr->invalid = 1; | |
6482 | } | |
6483 | } | |
6484 | else | |
6485 | invalidate_any_buried_refs (PATTERN (insn)); | |
6486 | } | |
6487 | } | |
6488 | } | |
6489 | } | |
6490 | ||
6491 | /* Remove any references that have been either invalidated or are not in the | |
6492 | expression list for pre gcse. */ | |
6493 | ||
6494 | static void | |
6495 | trim_ld_motion_mems () | |
6496 | { | |
6497 | struct ls_expr * last = NULL; | |
6498 | struct ls_expr * ptr = first_ls_expr (); | |
6499 | ||
6500 | while (ptr != NULL) | |
6501 | { | |
6502 | int del = ptr->invalid; | |
6503 | struct expr * expr = NULL; | |
6504 | ||
6505 | /* Delete if entry has been made invalid. */ | |
6506 | if (!del) | |
6507 | { | |
6508 | unsigned int i; | |
6509 | ||
6510 | del = 1; | |
6511 | /* Delete if we cannot find this mem in the expression list. */ | |
6512 | for (i = 0; i < expr_hash_table_size && del; i++) | |
6513 | { | |
6514 | for (expr = expr_hash_table[i]; | |
6515 | expr != NULL; | |
6516 | expr = expr->next_same_hash) | |
6517 | if (expr_equiv_p (expr->expr, ptr->pattern)) | |
6518 | { | |
6519 | del = 0; | |
6520 | break; | |
6521 | } | |
6522 | } | |
6523 | } | |
6524 | ||
6525 | if (del) | |
6526 | { | |
6527 | if (last != NULL) | |
6528 | { | |
6529 | last->next = ptr->next; | |
6530 | free_ldst_entry (ptr); | |
6531 | ptr = last->next; | |
6532 | } | |
6533 | else | |
6534 | { | |
6535 | pre_ldst_mems = pre_ldst_mems->next; | |
6536 | free_ldst_entry (ptr); | |
6537 | ptr = pre_ldst_mems; | |
6538 | } | |
6539 | } | |
6540 | else | |
6541 | { | |
6542 | /* Set the expression field if we are keeping it. */ | |
6543 | last = ptr; | |
6544 | ptr->expr = expr; | |
6545 | ptr = ptr->next; | |
6546 | } | |
6547 | } | |
6548 | ||
6549 | /* Show the world what we've found. */ | |
6550 | if (gcse_file && pre_ldst_mems != NULL) | |
6551 | print_ldst_list (gcse_file); | |
6552 | } | |
6553 | ||
6554 | /* This routine will take an expression which we are replacing with | |
6555 | a reaching register, and update any stores that are needed if | |
6556 | that expression is in the ld_motion list. Stores are updated by | |
6557 | copying their SRC to the reaching register, and then storeing | |
6558 | the reaching register into the store location. These keeps the | |
6559 | correct value in the reaching register for the loads. */ | |
6560 | ||
6561 | static void | |
6562 | update_ld_motion_stores (expr) | |
6563 | struct expr * expr; | |
6564 | { | |
6565 | struct ls_expr * mem_ptr; | |
6566 | ||
6567 | if ((mem_ptr = find_rtx_in_ldst (expr->expr))) | |
6568 | { | |
6569 | /* We can try to find just the REACHED stores, but is shouldn't | |
6570 | matter to set the reaching reg everywhere... some might be | |
6571 | dead and should be eliminated later. */ | |
6572 | ||
6573 | /* We replace SET mem = expr with | |
6574 | SET reg = expr | |
6575 | SET mem = reg , where reg is the | |
6576 | reaching reg used in the load. */ | |
6577 | rtx list = mem_ptr->stores; | |
6578 | ||
6579 | for ( ; list != NULL_RTX; list = XEXP (list, 1)) | |
6580 | { | |
6581 | rtx insn = XEXP (list, 0); | |
6582 | rtx pat = PATTERN (insn); | |
6583 | rtx src = SET_SRC (pat); | |
6584 | rtx reg = expr->reaching_reg; | |
6585 | rtx copy, new; | |
6586 | ||
6587 | /* If we've already copied it, continue. */ | |
6588 | if (expr->reaching_reg == src) | |
6589 | continue; | |
6590 | ||
6591 | if (gcse_file) | |
6592 | { | |
6593 | fprintf (gcse_file, "PRE: store updated with reaching reg "); | |
6594 | print_rtl (gcse_file, expr->reaching_reg); | |
6595 | fprintf (gcse_file, ":\n "); | |
6596 | print_inline_rtx (gcse_file, insn, 8); | |
6597 | fprintf (gcse_file, "\n"); | |
6598 | } | |
6599 | ||
6600 | copy = gen_move_insn ( reg, SET_SRC (pat)); | |
6601 | new = emit_insn_before (copy, insn); | |
6602 | record_one_set (REGNO (reg), new); | |
6603 | SET_SRC (pat) = reg; | |
6604 | ||
6605 | /* un-recognize this pattern since it's probably different now. */ | |
6606 | INSN_CODE (insn) = -1; | |
6607 | gcse_create_count++; | |
6608 | } | |
6609 | } | |
6610 | } | |
6611 | \f | |
6612 | /* Store motion code. */ | |
6613 | ||
6614 | /* This is used to communicate the target bitvector we want to use in the | |
6615 | reg_set_info routine when called via the note_stores mechanism. */ | |
6616 | static sbitmap * regvec; | |
6617 | ||
6618 | /* Used in computing the reverse edge graph bit vectors. */ | |
6619 | static sbitmap * st_antloc; | |
6620 | ||
6621 | /* Global holding the number of store expressions we are dealing with. */ | |
6622 | static int num_stores; | |
6623 | ||
6624 | /* Checks to set if we need to mark a register set. Called from note_stores. */ | |
6625 | ||
6626 | static void | |
6627 | reg_set_info (dest, setter, data) | |
6628 | rtx dest, setter ATTRIBUTE_UNUSED; | |
6629 | void * data ATTRIBUTE_UNUSED; | |
6630 | { | |
6631 | if (GET_CODE (dest) == SUBREG) | |
6632 | dest = SUBREG_REG (dest); | |
6633 | ||
6634 | if (GET_CODE (dest) == REG) | |
6635 | SET_BIT (*regvec, REGNO (dest)); | |
6636 | } | |
6637 | ||
6638 | /* Return non-zero if the register operands of expression X are killed | |
6639 | anywhere in basic block BB. */ | |
6640 | ||
6641 | static int | |
6642 | store_ops_ok (x, bb) | |
6643 | rtx x; | |
6644 | basic_block bb; | |
6645 | { | |
6646 | int i; | |
6647 | enum rtx_code code; | |
6648 | const char * fmt; | |
6649 | ||
6650 | /* Repeat is used to turn tail-recursion into iteration. */ | |
6651 | repeat: | |
6652 | ||
6653 | if (x == 0) | |
6654 | return 1; | |
6655 | ||
6656 | code = GET_CODE (x); | |
6657 | switch (code) | |
6658 | { | |
6659 | case REG: | |
6660 | /* If a reg has changed after us in this | |
6661 | block, the operand has been killed. */ | |
6662 | return TEST_BIT (reg_set_in_block[bb->index], REGNO (x)); | |
6663 | ||
6664 | case MEM: | |
6665 | x = XEXP (x, 0); | |
6666 | goto repeat; | |
6667 | ||
6668 | case PRE_DEC: | |
6669 | case PRE_INC: | |
6670 | case POST_DEC: | |
6671 | case POST_INC: | |
6672 | return 0; | |
6673 | ||
6674 | case PC: | |
6675 | case CC0: /*FIXME*/ | |
6676 | case CONST: | |
6677 | case CONST_INT: | |
6678 | case CONST_DOUBLE: | |
6679 | case CONST_VECTOR: | |
6680 | case SYMBOL_REF: | |
6681 | case LABEL_REF: | |
6682 | case ADDR_VEC: | |
6683 | case ADDR_DIFF_VEC: | |
6684 | return 1; | |
6685 | ||
6686 | default: | |
6687 | break; | |
6688 | } | |
6689 | ||
6690 | i = GET_RTX_LENGTH (code) - 1; | |
6691 | fmt = GET_RTX_FORMAT (code); | |
6692 | ||
6693 | for (; i >= 0; i--) | |
6694 | { | |
6695 | if (fmt[i] == 'e') | |
6696 | { | |
6697 | rtx tem = XEXP (x, i); | |
6698 | ||
6699 | /* If we are about to do the last recursive call | |
6700 | needed at this level, change it into iteration. | |
6701 | This function is called enough to be worth it. */ | |
6702 | if (i == 0) | |
6703 | { | |
6704 | x = tem; | |
6705 | goto repeat; | |
6706 | } | |
6707 | ||
6708 | if (! store_ops_ok (tem, bb)) | |
6709 | return 0; | |
6710 | } | |
6711 | else if (fmt[i] == 'E') | |
6712 | { | |
6713 | int j; | |
6714 | ||
6715 | for (j = 0; j < XVECLEN (x, i); j++) | |
6716 | { | |
6717 | if (! store_ops_ok (XVECEXP (x, i, j), bb)) | |
6718 | return 0; | |
6719 | } | |
6720 | } | |
6721 | } | |
6722 | ||
6723 | return 1; | |
6724 | } | |
6725 | ||
6726 | /* Determine whether insn is MEM store pattern that we will consider moving. */ | |
6727 | ||
6728 | static void | |
6729 | find_moveable_store (insn) | |
6730 | rtx insn; | |
6731 | { | |
6732 | struct ls_expr * ptr; | |
6733 | rtx dest = PATTERN (insn); | |
6734 | ||
6735 | if (GET_CODE (dest) != SET | |
6736 | || GET_CODE (SET_SRC (dest)) == ASM_OPERANDS) | |
6737 | return; | |
6738 | ||
6739 | dest = SET_DEST (dest); | |
6740 | ||
6741 | if (GET_CODE (dest) != MEM || MEM_VOLATILE_P (dest) | |
6742 | || GET_MODE (dest) == BLKmode) | |
6743 | return; | |
6744 | ||
6745 | if (GET_CODE (XEXP (dest, 0)) != SYMBOL_REF) | |
6746 | return; | |
6747 | ||
6748 | if (rtx_varies_p (XEXP (dest, 0), 0)) | |
6749 | return; | |
6750 | ||
6751 | ptr = ldst_entry (dest); | |
6752 | ptr->stores = alloc_INSN_LIST (insn, ptr->stores); | |
6753 | } | |
6754 | ||
6755 | /* Perform store motion. Much like gcse, except we move expressions the | |
6756 | other way by looking at the flowgraph in reverse. */ | |
6757 | ||
6758 | static int | |
6759 | compute_store_table () | |
6760 | { | |
6761 | int ret; | |
6762 | basic_block bb; | |
6763 | unsigned regno; | |
6764 | rtx insn, pat; | |
6765 | ||
6766 | max_gcse_regno = max_reg_num (); | |
6767 | ||
6768 | reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (last_basic_block, | |
6769 | max_gcse_regno); | |
6770 | sbitmap_vector_zero (reg_set_in_block, last_basic_block); | |
6771 | pre_ldst_mems = 0; | |
6772 | ||
6773 | /* Find all the stores we care about. */ | |
6774 | FOR_EACH_BB (bb) | |
6775 | { | |
6776 | regvec = & (reg_set_in_block[bb->index]); | |
6777 | for (insn = bb->end; | |
6778 | insn && insn != PREV_INSN (bb->end); | |
6779 | insn = PREV_INSN (insn)) | |
6780 | { | |
6781 | /* Ignore anything that is not a normal insn. */ | |
6782 | if (! INSN_P (insn)) | |
6783 | continue; | |
6784 | ||
6785 | if (GET_CODE (insn) == CALL_INSN) | |
6786 | { | |
6787 | bool clobbers_all = false; | |
6788 | #ifdef NON_SAVING_SETJMP | |
6789 | if (NON_SAVING_SETJMP | |
6790 | && find_reg_note (insn, REG_SETJMP, NULL_RTX)) | |
6791 | clobbers_all = true; | |
6792 | #endif | |
6793 | ||
6794 | for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) | |
6795 | if (clobbers_all | |
6796 | || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno)) | |
6797 | SET_BIT (reg_set_in_block[bb->index], regno); | |
6798 | } | |
6799 | ||
6800 | pat = PATTERN (insn); | |
6801 | note_stores (pat, reg_set_info, NULL); | |
6802 | ||
6803 | /* Now that we've marked regs, look for stores. */ | |
6804 | if (GET_CODE (pat) == SET) | |
6805 | find_moveable_store (insn); | |
6806 | } | |
6807 | } | |
6808 | ||
6809 | ret = enumerate_ldsts (); | |
6810 | ||
6811 | if (gcse_file) | |
6812 | { | |
6813 | fprintf (gcse_file, "Store Motion Expressions.\n"); | |
6814 | print_ldst_list (gcse_file); | |
6815 | } | |
6816 | ||
6817 | return ret; | |
6818 | } | |
6819 | ||
6820 | /* Check to see if the load X is aliased with STORE_PATTERN. */ | |
6821 | ||
6822 | static int | |
6823 | load_kills_store (x, store_pattern) | |
6824 | rtx x, store_pattern; | |
6825 | { | |
6826 | if (true_dependence (x, GET_MODE (x), store_pattern, rtx_addr_varies_p)) | |
6827 | return 1; | |
6828 | return 0; | |
6829 | } | |
6830 | ||
6831 | /* Go through the entire insn X, looking for any loads which might alias | |
6832 | STORE_PATTERN. Return 1 if found. */ | |
6833 | ||
6834 | static int | |
6835 | find_loads (x, store_pattern) | |
6836 | rtx x, store_pattern; | |
6837 | { | |
6838 | const char * fmt; | |
6839 | int i, j; | |
6840 | int ret = 0; | |
6841 | ||
6842 | if (!x) | |
6843 | return 0; | |
6844 | ||
6845 | if (GET_CODE (x) == SET) | |
6846 | x = SET_SRC (x); | |
6847 | ||
6848 | if (GET_CODE (x) == MEM) | |
6849 | { | |
6850 | if (load_kills_store (x, store_pattern)) | |
6851 | return 1; | |
6852 | } | |
6853 | ||
6854 | /* Recursively process the insn. */ | |
6855 | fmt = GET_RTX_FORMAT (GET_CODE (x)); | |
6856 | ||
6857 | for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--) | |
6858 | { | |
6859 | if (fmt[i] == 'e') | |
6860 | ret |= find_loads (XEXP (x, i), store_pattern); | |
6861 | else if (fmt[i] == 'E') | |
6862 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
6863 | ret |= find_loads (XVECEXP (x, i, j), store_pattern); | |
6864 | } | |
6865 | return ret; | |
6866 | } | |
6867 | ||
6868 | /* Check if INSN kills the store pattern X (is aliased with it). | |
6869 | Return 1 if it it does. */ | |
6870 | ||
6871 | static int | |
6872 | store_killed_in_insn (x, insn) | |
6873 | rtx x, insn; | |
6874 | { | |
6875 | if (GET_RTX_CLASS (GET_CODE (insn)) != 'i') | |
6876 | return 0; | |
6877 | ||
6878 | if (GET_CODE (insn) == CALL_INSN) | |
6879 | { | |
6880 | /* A normal or pure call might read from pattern, | |
6881 | but a const call will not. */ | |
6882 | return ! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn); | |
6883 | } | |
6884 | ||
6885 | if (GET_CODE (PATTERN (insn)) == SET) | |
6886 | { | |
6887 | rtx pat = PATTERN (insn); | |
6888 | /* Check for memory stores to aliased objects. */ | |
6889 | if (GET_CODE (SET_DEST (pat)) == MEM && !expr_equiv_p (SET_DEST (pat), x)) | |
6890 | /* pretend its a load and check for aliasing. */ | |
6891 | if (find_loads (SET_DEST (pat), x)) | |
6892 | return 1; | |
6893 | return find_loads (SET_SRC (pat), x); | |
6894 | } | |
6895 | else | |
6896 | return find_loads (PATTERN (insn), x); | |
6897 | } | |
6898 | ||
6899 | /* Returns 1 if the expression X is loaded or clobbered on or after INSN | |
6900 | within basic block BB. */ | |
6901 | ||
6902 | static int | |
6903 | store_killed_after (x, insn, bb) | |
6904 | rtx x, insn; | |
6905 | basic_block bb; | |
6906 | { | |
6907 | rtx last = bb->end; | |
6908 | ||
6909 | if (insn == last) | |
6910 | return 0; | |
6911 | ||
6912 | /* Check if the register operands of the store are OK in this block. | |
6913 | Note that if registers are changed ANYWHERE in the block, we'll | |
6914 | decide we can't move it, regardless of whether it changed above | |
6915 | or below the store. This could be improved by checking the register | |
6916 | operands while lookinng for aliasing in each insn. */ | |
6917 | if (!store_ops_ok (XEXP (x, 0), bb)) | |
6918 | return 1; | |
6919 | ||
6920 | for ( ; insn && insn != NEXT_INSN (last); insn = NEXT_INSN (insn)) | |
6921 | if (store_killed_in_insn (x, insn)) | |
6922 | return 1; | |
6923 | ||
6924 | return 0; | |
6925 | } | |
6926 | ||
6927 | /* Returns 1 if the expression X is loaded or clobbered on or before INSN | |
6928 | within basic block BB. */ | |
6929 | static int | |
6930 | store_killed_before (x, insn, bb) | |
6931 | rtx x, insn; | |
6932 | basic_block bb; | |
6933 | { | |
6934 | rtx first = bb->head; | |
6935 | ||
6936 | if (insn == first) | |
6937 | return store_killed_in_insn (x, insn); | |
6938 | ||
6939 | /* Check if the register operands of the store are OK in this block. | |
6940 | Note that if registers are changed ANYWHERE in the block, we'll | |
6941 | decide we can't move it, regardless of whether it changed above | |
6942 | or below the store. This could be improved by checking the register | |
6943 | operands while lookinng for aliasing in each insn. */ | |
6944 | if (!store_ops_ok (XEXP (x, 0), bb)) | |
6945 | return 1; | |
6946 | ||
6947 | for ( ; insn && insn != PREV_INSN (first); insn = PREV_INSN (insn)) | |
6948 | if (store_killed_in_insn (x, insn)) | |
6949 | return 1; | |
6950 | ||
6951 | return 0; | |
6952 | } | |
6953 | ||
6954 | #define ANTIC_STORE_LIST(x) ((x)->loads) | |
6955 | #define AVAIL_STORE_LIST(x) ((x)->stores) | |
6956 | ||
6957 | /* Given the table of available store insns at the end of blocks, | |
6958 | determine which ones are not killed by aliasing, and generate | |
6959 | the appropriate vectors for gen and killed. */ | |
6960 | static void | |
6961 | build_store_vectors () | |
6962 | { | |
6963 | basic_block bb, b; | |
6964 | rtx insn, st; | |
6965 | struct ls_expr * ptr; | |
6966 | ||
6967 | /* Build the gen_vector. This is any store in the table which is not killed | |
6968 | by aliasing later in its block. */ | |
6969 | ae_gen = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores); | |
6970 | sbitmap_vector_zero (ae_gen, last_basic_block); | |
6971 | ||
6972 | st_antloc = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores); | |
6973 | sbitmap_vector_zero (st_antloc, last_basic_block); | |
6974 | ||
6975 | for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr)) | |
6976 | { | |
6977 | /* Put all the stores into either the antic list, or the avail list, | |
6978 | or both. */ | |
6979 | rtx store_list = ptr->stores; | |
6980 | ptr->stores = NULL_RTX; | |
6981 | ||
6982 | for (st = store_list; st != NULL; st = XEXP (st, 1)) | |
6983 | { | |
6984 | insn = XEXP (st, 0); | |
6985 | bb = BLOCK_FOR_INSN (insn); | |
6986 | ||
6987 | if (!store_killed_after (ptr->pattern, insn, bb)) | |
6988 | { | |
6989 | /* If we've already seen an availale expression in this block, | |
6990 | we can delete the one we saw already (It occurs earlier in | |
6991 | the block), and replace it with this one). We'll copy the | |
6992 | old SRC expression to an unused register in case there | |
6993 | are any side effects. */ | |
6994 | if (TEST_BIT (ae_gen[bb->index], ptr->index)) | |
6995 | { | |
6996 | /* Find previous store. */ | |
6997 | rtx st; | |
6998 | for (st = AVAIL_STORE_LIST (ptr); st ; st = XEXP (st, 1)) | |
6999 | if (BLOCK_FOR_INSN (XEXP (st, 0)) == bb) | |
7000 | break; | |
7001 | if (st) | |
7002 | { | |
7003 | rtx r = gen_reg_rtx (GET_MODE (ptr->pattern)); | |
7004 | if (gcse_file) | |
7005 | fprintf (gcse_file, "Removing redundant store:\n"); | |
7006 | replace_store_insn (r, XEXP (st, 0), bb); | |
7007 | XEXP (st, 0) = insn; | |
7008 | continue; | |
7009 | } | |
7010 | } | |
7011 | SET_BIT (ae_gen[bb->index], ptr->index); | |
7012 | AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn, | |
7013 | AVAIL_STORE_LIST (ptr)); | |
7014 | } | |
7015 | ||
7016 | if (!store_killed_before (ptr->pattern, insn, bb)) | |
7017 | { | |
7018 | SET_BIT (st_antloc[BLOCK_NUM (insn)], ptr->index); | |
7019 | ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (insn, | |
7020 | ANTIC_STORE_LIST (ptr)); | |
7021 | } | |
7022 | } | |
7023 | ||
7024 | /* Free the original list of store insns. */ | |
7025 | free_INSN_LIST_list (&store_list); | |
7026 | } | |
7027 | ||
7028 | ae_kill = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores); | |
7029 | sbitmap_vector_zero (ae_kill, last_basic_block); | |
7030 | ||
7031 | transp = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores); | |
7032 | sbitmap_vector_zero (transp, last_basic_block); | |
7033 | ||
7034 | for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr)) | |
7035 | FOR_EACH_BB (b) | |
7036 | { | |
7037 | if (store_killed_after (ptr->pattern, b->head, b)) | |
7038 | { | |
7039 | /* The anticipatable expression is not killed if it's gen'd. */ | |
7040 | /* | |
7041 | We leave this check out for now. If we have a code sequence | |
7042 | in a block which looks like: | |
7043 | ST MEMa = x | |
7044 | L y = MEMa | |
7045 | ST MEMa = z | |
7046 | We should flag this as having an ANTIC expression, NOT | |
7047 | transparent, NOT killed, and AVAIL. | |
7048 | Unfortunately, since we haven't re-written all loads to | |
7049 | use the reaching reg, we'll end up doing an incorrect | |
7050 | Load in the middle here if we push the store down. It happens in | |
7051 | gcc.c-torture/execute/960311-1.c with -O3 | |
7052 | If we always kill it in this case, we'll sometimes do | |
7053 | uneccessary work, but it shouldn't actually hurt anything. | |
7054 | if (!TEST_BIT (ae_gen[b], ptr->index)). */ | |
7055 | SET_BIT (ae_kill[b->index], ptr->index); | |
7056 | } | |
7057 | else | |
7058 | SET_BIT (transp[b->index], ptr->index); | |
7059 | } | |
7060 | ||
7061 | /* Any block with no exits calls some non-returning function, so | |
7062 | we better mark the store killed here, or we might not store to | |
7063 | it at all. If we knew it was abort, we wouldn't have to store, | |
7064 | but we don't know that for sure. */ | |
7065 | if (gcse_file) | |
7066 | { | |
7067 | fprintf (gcse_file, "ST_avail and ST_antic (shown under loads..)\n"); | |
7068 | print_ldst_list (gcse_file); | |
7069 | dump_sbitmap_vector (gcse_file, "st_antloc", "", st_antloc, last_basic_block); | |
7070 | dump_sbitmap_vector (gcse_file, "st_kill", "", ae_kill, last_basic_block); | |
7071 | dump_sbitmap_vector (gcse_file, "Transpt", "", transp, last_basic_block); | |
7072 | dump_sbitmap_vector (gcse_file, "st_avloc", "", ae_gen, last_basic_block); | |
7073 | } | |
7074 | } | |
7075 | ||
7076 | /* Insert an instruction at the begining of a basic block, and update | |
7077 | the BLOCK_HEAD if needed. */ | |
7078 | ||
7079 | static void | |
7080 | insert_insn_start_bb (insn, bb) | |
7081 | rtx insn; | |
7082 | basic_block bb; | |
7083 | { | |
7084 | /* Insert at start of successor block. */ | |
7085 | rtx prev = PREV_INSN (bb->head); | |
7086 | rtx before = bb->head; | |
7087 | while (before != 0) | |
7088 | { | |
7089 | if (GET_CODE (before) != CODE_LABEL | |
7090 | && (GET_CODE (before) != NOTE | |
7091 | || NOTE_LINE_NUMBER (before) != NOTE_INSN_BASIC_BLOCK)) | |
7092 | break; | |
7093 | prev = before; | |
7094 | if (prev == bb->end) | |
7095 | break; | |
7096 | before = NEXT_INSN (before); | |
7097 | } | |
7098 | ||
7099 | insn = emit_insn_after (insn, prev); | |
7100 | ||
7101 | if (gcse_file) | |
7102 | { | |
7103 | fprintf (gcse_file, "STORE_MOTION insert store at start of BB %d:\n", | |
7104 | bb->index); | |
7105 | print_inline_rtx (gcse_file, insn, 6); | |
7106 | fprintf (gcse_file, "\n"); | |
7107 | } | |
7108 | } | |
7109 | ||
7110 | /* This routine will insert a store on an edge. EXPR is the ldst entry for | |
7111 | the memory reference, and E is the edge to insert it on. Returns non-zero | |
7112 | if an edge insertion was performed. */ | |
7113 | ||
7114 | static int | |
7115 | insert_store (expr, e) | |
7116 | struct ls_expr * expr; | |
7117 | edge e; | |
7118 | { | |
7119 | rtx reg, insn; | |
7120 | basic_block bb; | |
7121 | edge tmp; | |
7122 | ||
7123 | /* We did all the deleted before this insert, so if we didn't delete a | |
7124 | store, then we haven't set the reaching reg yet either. */ | |
7125 | if (expr->reaching_reg == NULL_RTX) | |
7126 | return 0; | |
7127 | ||
7128 | reg = expr->reaching_reg; | |
7129 | insn = gen_move_insn (expr->pattern, reg); | |
7130 | ||
7131 | /* If we are inserting this expression on ALL predecessor edges of a BB, | |
7132 | insert it at the start of the BB, and reset the insert bits on the other | |
7133 | edges so we don't try to insert it on the other edges. */ | |
7134 | bb = e->dest; | |
7135 | for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next) | |
7136 | { | |
7137 | int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest); | |
7138 | if (index == EDGE_INDEX_NO_EDGE) | |
7139 | abort (); | |
7140 | if (! TEST_BIT (pre_insert_map[index], expr->index)) | |
7141 | break; | |
7142 | } | |
7143 | ||
7144 | /* If tmp is NULL, we found an insertion on every edge, blank the | |
7145 | insertion vector for these edges, and insert at the start of the BB. */ | |
7146 | if (!tmp && bb != EXIT_BLOCK_PTR) | |
7147 | { | |
7148 | for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next) | |
7149 | { | |
7150 | int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest); | |
7151 | RESET_BIT (pre_insert_map[index], expr->index); | |
7152 | } | |
7153 | insert_insn_start_bb (insn, bb); | |
7154 | return 0; | |
7155 | } | |
7156 | ||
7157 | /* We can't insert on this edge, so we'll insert at the head of the | |
7158 | successors block. See Morgan, sec 10.5. */ | |
7159 | if ((e->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL) | |
7160 | { | |
7161 | insert_insn_start_bb (insn, bb); | |
7162 | return 0; | |
7163 | } | |
7164 | ||
7165 | insert_insn_on_edge (insn, e); | |
7166 | ||
7167 | if (gcse_file) | |
7168 | { | |
7169 | fprintf (gcse_file, "STORE_MOTION insert insn on edge (%d, %d):\n", | |
7170 | e->src->index, e->dest->index); | |
7171 | print_inline_rtx (gcse_file, insn, 6); | |
7172 | fprintf (gcse_file, "\n"); | |
7173 | } | |
7174 | ||
7175 | return 1; | |
7176 | } | |
7177 | ||
7178 | /* This routine will replace a store with a SET to a specified register. */ | |
7179 | ||
7180 | static void | |
7181 | replace_store_insn (reg, del, bb) | |
7182 | rtx reg, del; | |
7183 | basic_block bb; | |
7184 | { | |
7185 | rtx insn; | |
7186 | ||
7187 | insn = gen_move_insn (reg, SET_SRC (PATTERN (del))); | |
7188 | insn = emit_insn_after (insn, del); | |
7189 | ||
7190 | if (gcse_file) | |
7191 | { | |
7192 | fprintf (gcse_file, | |
7193 | "STORE_MOTION delete insn in BB %d:\n ", bb->index); | |
7194 | print_inline_rtx (gcse_file, del, 6); | |
7195 | fprintf (gcse_file, "\nSTORE MOTION replaced with insn:\n "); | |
7196 | print_inline_rtx (gcse_file, insn, 6); | |
7197 | fprintf (gcse_file, "\n"); | |
7198 | } | |
7199 | ||
7200 | delete_insn (del); | |
7201 | } | |
7202 | ||
7203 | ||
7204 | /* Delete a store, but copy the value that would have been stored into | |
7205 | the reaching_reg for later storing. */ | |
7206 | ||
7207 | static void | |
7208 | delete_store (expr, bb) | |
7209 | struct ls_expr * expr; | |
7210 | basic_block bb; | |
7211 | { | |
7212 | rtx reg, i, del; | |
7213 | ||
7214 | if (expr->reaching_reg == NULL_RTX) | |
7215 | expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern)); | |
7216 | ||
7217 | ||
7218 | /* If there is more than 1 store, the earlier ones will be dead, | |
7219 | but it doesn't hurt to replace them here. */ | |
7220 | reg = expr->reaching_reg; | |
7221 | ||
7222 | for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1)) | |
7223 | { | |
7224 | del = XEXP (i, 0); | |
7225 | if (BLOCK_FOR_INSN (del) == bb) | |
7226 | { | |
7227 | /* We know there is only one since we deleted redundant | |
7228 | ones during the available computation. */ | |
7229 | replace_store_insn (reg, del, bb); | |
7230 | break; | |
7231 | } | |
7232 | } | |
7233 | } | |
7234 | ||
7235 | /* Free memory used by store motion. */ | |
7236 | ||
7237 | static void | |
7238 | free_store_memory () | |
7239 | { | |
7240 | free_ldst_mems (); | |
7241 | ||
7242 | if (ae_gen) | |
7243 | sbitmap_vector_free (ae_gen); | |
7244 | if (ae_kill) | |
7245 | sbitmap_vector_free (ae_kill); | |
7246 | if (transp) | |
7247 | sbitmap_vector_free (transp); | |
7248 | if (st_antloc) | |
7249 | sbitmap_vector_free (st_antloc); | |
7250 | if (pre_insert_map) | |
7251 | sbitmap_vector_free (pre_insert_map); | |
7252 | if (pre_delete_map) | |
7253 | sbitmap_vector_free (pre_delete_map); | |
7254 | if (reg_set_in_block) | |
7255 | sbitmap_vector_free (reg_set_in_block); | |
7256 | ||
7257 | ae_gen = ae_kill = transp = st_antloc = NULL; | |
7258 | pre_insert_map = pre_delete_map = reg_set_in_block = NULL; | |
7259 | } | |
7260 | ||
7261 | /* Perform store motion. Much like gcse, except we move expressions the | |
7262 | other way by looking at the flowgraph in reverse. */ | |
7263 | ||
7264 | static void | |
7265 | store_motion () | |
7266 | { | |
7267 | basic_block bb; | |
7268 | int x; | |
7269 | struct ls_expr * ptr; | |
7270 | int update_flow = 0; | |
7271 | ||
7272 | if (gcse_file) | |
7273 | { | |
7274 | fprintf (gcse_file, "before store motion\n"); | |
7275 | print_rtl (gcse_file, get_insns ()); | |
7276 | } | |
7277 | ||
7278 | ||
7279 | init_alias_analysis (); | |
7280 | ||
7281 | /* Find all the stores that are live to the end of their block. */ | |
7282 | num_stores = compute_store_table (); | |
7283 | if (num_stores == 0) | |
7284 | { | |
7285 | sbitmap_vector_free (reg_set_in_block); | |
7286 | end_alias_analysis (); | |
7287 | return; | |
7288 | } | |
7289 | ||
7290 | /* Now compute whats actually available to move. */ | |
7291 | add_noreturn_fake_exit_edges (); | |
7292 | build_store_vectors (); | |
7293 | ||
7294 | edge_list = pre_edge_rev_lcm (gcse_file, num_stores, transp, ae_gen, | |
7295 | st_antloc, ae_kill, &pre_insert_map, | |
7296 | &pre_delete_map); | |
7297 | ||
7298 | /* Now we want to insert the new stores which are going to be needed. */ | |
7299 | for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr)) | |
7300 | { | |
7301 | FOR_EACH_BB (bb) | |
7302 | if (TEST_BIT (pre_delete_map[bb->index], ptr->index)) | |
7303 | delete_store (ptr, bb); | |
7304 | ||
7305 | for (x = 0; x < NUM_EDGES (edge_list); x++) | |
7306 | if (TEST_BIT (pre_insert_map[x], ptr->index)) | |
7307 | update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x)); | |
7308 | } | |
7309 | ||
7310 | if (update_flow) | |
7311 | commit_edge_insertions (); | |
7312 | ||
7313 | free_store_memory (); | |
7314 | free_edge_list (edge_list); | |
7315 | remove_fake_edges (); | |
7316 | end_alias_analysis (); | |
7317 | } | |
7318 | ||
7319 | #include "gt-gcse.h" |