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f4e584dc | 1 | /* Global common subexpression elimination/Partial redundancy elimination |
7506f491 | 2 | and global constant/copy propagation for GNU compiler. |
a5cad800 | 3 | Copyright (C) 1997, 1998, 1999 Free Software Foundation, Inc. |
7506f491 DE |
4 | |
5 | This file is part of GNU CC. | |
6 | ||
7 | GNU CC is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2, or (at your option) | |
10 | any later version. | |
11 | ||
12 | GNU CC is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GNU CC; see the file COPYING. If not, write to | |
19 | the Free Software Foundation, 59 Temple Place - Suite 330, | |
20 | Boston, MA 02111-1307, USA. */ | |
21 | ||
22 | /* TODO | |
23 | - reordering of memory allocation and freeing to be more space efficient | |
24 | - do rough calc of how many regs are needed in each block, and a rough | |
25 | calc of how many regs are available in each class and use that to | |
26 | throttle back the code in cases where RTX_COST is minimal. | |
f4e584dc JL |
27 | - dead store elimination |
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. | |
7506f491 DE |
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 | ||
7506f491 DE |
35 | */ |
36 | ||
37 | /* References searched while implementing this. | |
7506f491 DE |
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 | ||
7506f491 DE |
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 | ||
7506f491 DE |
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 | ||
f4e584dc JL |
125 | Advanced Compiler Design and Implementation |
126 | Steven Muchnick | |
127 | Morgan Kaufmann, 1997 | |
128 | ||
a42cd965 AM |
129 | Building an Optimizing Compiler |
130 | Robert Morgan | |
131 | Digital Press, 1998 | |
132 | ||
f4e584dc JL |
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 | ||
7506f491 DE |
142 | People wishing to do something different can find various possibilities |
143 | in the above papers and elsewhere. | |
144 | */ | |
145 | ||
146 | #include "config.h" | |
50b2596f | 147 | #include "system.h" |
01198c2f | 148 | #include "toplev.h" |
7506f491 DE |
149 | |
150 | #include "rtl.h" | |
6baf1cc8 | 151 | #include "tm_p.h" |
7506f491 DE |
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" | |
50b2596f | 159 | #include "output.h" |
49ad7cfa | 160 | #include "function.h" |
3cdbd1f8 | 161 | #include "expr.h" |
7506f491 DE |
162 | |
163 | #include "obstack.h" | |
164 | #define obstack_chunk_alloc gmalloc | |
165 | #define obstack_chunk_free free | |
166 | ||
167 | /* Maximum number of passes to perform. */ | |
168 | #define MAX_PASSES 1 | |
169 | ||
170 | /* Propagate flow information through back edges and thus enable PRE's | |
171 | moving loop invariant calculations out of loops. | |
172 | ||
173 | Originally this tended to create worse overall code, but several | |
174 | improvements during the development of PRE seem to have made following | |
175 | back edges generally a win. | |
176 | ||
177 | Note much of the loop invariant code motion done here would normally | |
178 | be done by loop.c, which has more heuristics for when to move invariants | |
179 | out of loops. At some point we might need to move some of those | |
180 | heuristics into gcse.c. */ | |
181 | #define FOLLOW_BACK_EDGES 1 | |
182 | ||
f4e584dc JL |
183 | /* We support GCSE via Partial Redundancy Elimination. PRE optimizations |
184 | are a superset of those done by GCSE. | |
7506f491 | 185 | |
f4e584dc | 186 | We perform the following steps: |
7506f491 DE |
187 | |
188 | 1) Compute basic block information. | |
189 | ||
190 | 2) Compute table of places where registers are set. | |
191 | ||
192 | 3) Perform copy/constant propagation. | |
193 | ||
194 | 4) Perform global cse. | |
195 | ||
e78d9500 | 196 | 5) Perform another pass of copy/constant propagation. |
7506f491 DE |
197 | |
198 | Two passes of copy/constant propagation are done because the first one | |
199 | enables more GCSE and the second one helps to clean up the copies that | |
200 | GCSE creates. This is needed more for PRE than for Classic because Classic | |
201 | GCSE will try to use an existing register containing the common | |
202 | subexpression rather than create a new one. This is harder to do for PRE | |
203 | because of the code motion (which Classic GCSE doesn't do). | |
204 | ||
205 | Expressions we are interested in GCSE-ing are of the form | |
206 | (set (pseudo-reg) (expression)). | |
207 | Function want_to_gcse_p says what these are. | |
208 | ||
209 | PRE handles moving invariant expressions out of loops (by treating them as | |
f4e584dc | 210 | partially redundant). |
7506f491 DE |
211 | |
212 | Eventually it would be nice to replace cse.c/gcse.c with SSA (static single | |
213 | assignment) based GVN (global value numbering). L. T. Simpson's paper | |
214 | (Rice University) on value numbering is a useful reference for this. | |
215 | ||
216 | ********************** | |
217 | ||
218 | We used to support multiple passes but there are diminishing returns in | |
219 | doing so. The first pass usually makes 90% of the changes that are doable. | |
220 | A second pass can make a few more changes made possible by the first pass. | |
221 | Experiments show any further passes don't make enough changes to justify | |
222 | the expense. | |
223 | ||
224 | A study of spec92 using an unlimited number of passes: | |
225 | [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83, | |
226 | [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2, | |
227 | [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1 | |
228 | ||
229 | It was found doing copy propagation between each pass enables further | |
230 | substitutions. | |
231 | ||
232 | PRE is quite expensive in complicated functions because the DFA can take | |
233 | awhile to converge. Hence we only perform one pass. Macro MAX_PASSES can | |
234 | be modified if one wants to experiment. | |
235 | ||
236 | ********************** | |
237 | ||
238 | The steps for PRE are: | |
239 | ||
240 | 1) Build the hash table of expressions we wish to GCSE (expr_hash_table). | |
241 | ||
242 | 2) Perform the data flow analysis for PRE. | |
243 | ||
244 | 3) Delete the redundant instructions | |
245 | ||
246 | 4) Insert the required copies [if any] that make the partially | |
247 | redundant instructions fully redundant. | |
248 | ||
249 | 5) For other reaching expressions, insert an instruction to copy the value | |
250 | to a newly created pseudo that will reach the redundant instruction. | |
251 | ||
252 | The deletion is done first so that when we do insertions we | |
253 | know which pseudo reg to use. | |
254 | ||
255 | Various papers have argued that PRE DFA is expensive (O(n^2)) and others | |
256 | argue it is not. The number of iterations for the algorithm to converge | |
257 | is typically 2-4 so I don't view it as that expensive (relatively speaking). | |
258 | ||
f4e584dc | 259 | PRE GCSE depends heavily on the second CSE pass to clean up the copies |
7506f491 DE |
260 | we create. To make an expression reach the place where it's redundant, |
261 | the result of the expression is copied to a new register, and the redundant | |
262 | expression is deleted by replacing it with this new register. Classic GCSE | |
263 | doesn't have this problem as much as it computes the reaching defs of | |
264 | each register in each block and thus can try to use an existing register. | |
265 | ||
266 | ********************** | |
267 | ||
7506f491 DE |
268 | A fair bit of simplicity is created by creating small functions for simple |
269 | tasks, even when the function is only called in one place. This may | |
270 | measurably slow things down [or may not] by creating more function call | |
271 | overhead than is necessary. The source is laid out so that it's trivial | |
272 | to make the affected functions inline so that one can measure what speed | |
273 | up, if any, can be achieved, and maybe later when things settle things can | |
274 | be rearranged. | |
275 | ||
276 | Help stamp out big monolithic functions! */ | |
277 | \f | |
278 | /* GCSE global vars. */ | |
279 | ||
280 | /* -dG dump file. */ | |
281 | static FILE *gcse_file; | |
282 | ||
f4e584dc JL |
283 | /* Note whether or not we should run jump optimization after gcse. We |
284 | want to do this for two cases. | |
285 | ||
286 | * If we changed any jumps via cprop. | |
287 | ||
288 | * If we added any labels via edge splitting. */ | |
289 | ||
290 | static int run_jump_opt_after_gcse; | |
291 | ||
7506f491 DE |
292 | /* Bitmaps are normally not included in debugging dumps. |
293 | However it's useful to be able to print them from GDB. | |
294 | We could create special functions for this, but it's simpler to | |
295 | just allow passing stderr to the dump_foo fns. Since stderr can | |
296 | be a macro, we store a copy here. */ | |
297 | static FILE *debug_stderr; | |
298 | ||
299 | /* An obstack for our working variables. */ | |
300 | static struct obstack gcse_obstack; | |
301 | ||
302 | /* Non-zero for each mode that supports (set (reg) (reg)). | |
303 | This is trivially true for integer and floating point values. | |
304 | It may or may not be true for condition codes. */ | |
305 | static char can_copy_p[(int) NUM_MACHINE_MODES]; | |
306 | ||
307 | /* Non-zero if can_copy_p has been initialized. */ | |
308 | static int can_copy_init_p; | |
309 | ||
abd535b6 BS |
310 | struct reg_use { |
311 | rtx reg_rtx; | |
312 | }; | |
313 | ||
7506f491 DE |
314 | /* Hash table of expressions. */ |
315 | ||
316 | struct expr | |
317 | { | |
318 | /* The expression (SET_SRC for expressions, PATTERN for assignments). */ | |
319 | rtx expr; | |
320 | /* Index in the available expression bitmaps. */ | |
321 | int bitmap_index; | |
322 | /* Next entry with the same hash. */ | |
323 | struct expr *next_same_hash; | |
324 | /* List of anticipatable occurrences in basic blocks in the function. | |
325 | An "anticipatable occurrence" is one that is the first occurrence in the | |
f4e584dc JL |
326 | basic block, the operands are not modified in the basic block prior |
327 | to the occurrence and the output is not used between the start of | |
328 | the block and the occurrence. */ | |
7506f491 DE |
329 | struct occr *antic_occr; |
330 | /* List of available occurrence in basic blocks in the function. | |
331 | An "available occurrence" is one that is the last occurrence in the | |
332 | basic block and the operands are not modified by following statements in | |
333 | the basic block [including this insn]. */ | |
334 | struct occr *avail_occr; | |
335 | /* Non-null if the computation is PRE redundant. | |
336 | The value is the newly created pseudo-reg to record a copy of the | |
337 | expression in all the places that reach the redundant copy. */ | |
338 | rtx reaching_reg; | |
339 | }; | |
340 | ||
341 | /* Occurrence of an expression. | |
342 | There is one per basic block. If a pattern appears more than once the | |
343 | last appearance is used [or first for anticipatable expressions]. */ | |
344 | ||
345 | struct occr | |
346 | { | |
347 | /* Next occurrence of this expression. */ | |
348 | struct occr *next; | |
349 | /* The insn that computes the expression. */ | |
350 | rtx insn; | |
351 | /* Non-zero if this [anticipatable] occurrence has been deleted. */ | |
352 | char deleted_p; | |
353 | /* Non-zero if this [available] occurrence has been copied to | |
354 | reaching_reg. */ | |
355 | /* ??? This is mutually exclusive with deleted_p, so they could share | |
356 | the same byte. */ | |
357 | char copied_p; | |
358 | }; | |
359 | ||
360 | /* Expression and copy propagation hash tables. | |
361 | Each hash table is an array of buckets. | |
362 | ??? It is known that if it were an array of entries, structure elements | |
363 | `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is | |
364 | not clear whether in the final analysis a sufficient amount of memory would | |
365 | be saved as the size of the available expression bitmaps would be larger | |
366 | [one could build a mapping table without holes afterwards though]. | |
367 | Someday I'll perform the computation and figure it out. | |
368 | */ | |
369 | ||
370 | /* Total size of the expression hash table, in elements. */ | |
371 | static int expr_hash_table_size; | |
372 | /* The table itself. | |
373 | This is an array of `expr_hash_table_size' elements. */ | |
374 | static struct expr **expr_hash_table; | |
375 | ||
376 | /* Total size of the copy propagation hash table, in elements. */ | |
377 | static int set_hash_table_size; | |
378 | /* The table itself. | |
379 | This is an array of `set_hash_table_size' elements. */ | |
380 | static struct expr **set_hash_table; | |
381 | ||
382 | /* Mapping of uids to cuids. | |
383 | Only real insns get cuids. */ | |
384 | static int *uid_cuid; | |
385 | ||
386 | /* Highest UID in UID_CUID. */ | |
387 | static int max_uid; | |
388 | ||
389 | /* Get the cuid of an insn. */ | |
390 | #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)]) | |
391 | ||
392 | /* Number of cuids. */ | |
393 | static int max_cuid; | |
394 | ||
395 | /* Mapping of cuids to insns. */ | |
396 | static rtx *cuid_insn; | |
397 | ||
398 | /* Get insn from cuid. */ | |
399 | #define CUID_INSN(CUID) (cuid_insn[CUID]) | |
400 | ||
401 | /* Maximum register number in function prior to doing gcse + 1. | |
402 | Registers created during this pass have regno >= max_gcse_regno. | |
403 | This is named with "gcse" to not collide with global of same name. */ | |
404 | static int max_gcse_regno; | |
405 | ||
406 | /* Maximum number of cse-able expressions found. */ | |
407 | static int n_exprs; | |
408 | /* Maximum number of assignments for copy propagation found. */ | |
409 | static int n_sets; | |
410 | ||
411 | /* Table of registers that are modified. | |
412 | For each register, each element is a list of places where the pseudo-reg | |
413 | is set. | |
414 | ||
415 | For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only | |
416 | requires knowledge of which blocks kill which regs [and thus could use | |
f4e584dc | 417 | a bitmap instead of the lists `reg_set_table' uses]. |
7506f491 | 418 | |
f4e584dc JL |
419 | `reg_set_table' and could be turned into an array of bitmaps |
420 | (num-bbs x num-regs) | |
7506f491 DE |
421 | [however perhaps it may be useful to keep the data as is]. |
422 | One advantage of recording things this way is that `reg_set_table' is | |
423 | fairly sparse with respect to pseudo regs but for hard regs could be | |
424 | fairly dense [relatively speaking]. | |
425 | And recording sets of pseudo-regs in lists speeds | |
426 | up functions like compute_transp since in the case of pseudo-regs we only | |
427 | need to iterate over the number of times a pseudo-reg is set, not over the | |
428 | number of basic blocks [clearly there is a bit of a slow down in the cases | |
429 | where a pseudo is set more than once in a block, however it is believed | |
430 | that the net effect is to speed things up]. This isn't done for hard-regs | |
431 | because recording call-clobbered hard-regs in `reg_set_table' at each | |
432 | function call can consume a fair bit of memory, and iterating over hard-regs | |
433 | stored this way in compute_transp will be more expensive. */ | |
434 | ||
435 | typedef struct reg_set { | |
436 | /* The next setting of this register. */ | |
437 | struct reg_set *next; | |
438 | /* The insn where it was set. */ | |
439 | rtx insn; | |
440 | } reg_set; | |
441 | static reg_set **reg_set_table; | |
442 | /* Size of `reg_set_table'. | |
443 | The table starts out at max_gcse_regno + slop, and is enlarged as | |
444 | necessary. */ | |
445 | static int reg_set_table_size; | |
446 | /* Amount to grow `reg_set_table' by when it's full. */ | |
447 | #define REG_SET_TABLE_SLOP 100 | |
448 | ||
449 | /* Bitmap containing one bit for each register in the program. | |
450 | Used when performing GCSE to track which registers have been set since | |
451 | the start of the basic block. */ | |
452 | static sbitmap reg_set_bitmap; | |
453 | ||
454 | /* For each block, a bitmap of registers set in the block. | |
455 | This is used by expr_killed_p and compute_transp. | |
456 | It is computed during hash table computation and not by compute_sets | |
457 | as it includes registers added since the last pass (or between cprop and | |
458 | gcse) and it's currently not easy to realloc sbitmap vectors. */ | |
459 | static sbitmap *reg_set_in_block; | |
460 | ||
461 | /* For each block, non-zero if memory is set in that block. | |
462 | This is computed during hash table computation and is used by | |
463 | expr_killed_p and compute_transp. | |
464 | ??? Handling of memory is very simple, we don't make any attempt | |
465 | to optimize things (later). | |
466 | ??? This can be computed by compute_sets since the information | |
467 | doesn't change. */ | |
468 | static char *mem_set_in_block; | |
469 | ||
470 | /* Various variables for statistics gathering. */ | |
471 | ||
472 | /* Memory used in a pass. | |
473 | This isn't intended to be absolutely precise. Its intent is only | |
474 | to keep an eye on memory usage. */ | |
475 | static int bytes_used; | |
476 | /* GCSE substitutions made. */ | |
477 | static int gcse_subst_count; | |
478 | /* Number of copy instructions created. */ | |
479 | static int gcse_create_count; | |
480 | /* Number of constants propagated. */ | |
481 | static int const_prop_count; | |
482 | /* Number of copys propagated. */ | |
483 | static int copy_prop_count; | |
7506f491 DE |
484 | \f |
485 | /* These variables are used by classic GCSE. | |
486 | Normally they'd be defined a bit later, but `rd_gen' needs to | |
487 | be declared sooner. */ | |
488 | ||
489 | /* A bitmap of all ones for implementing the algorithm for available | |
490 | expressions and reaching definitions. */ | |
491 | /* ??? Available expression bitmaps have a different size than reaching | |
492 | definition bitmaps. This should be the larger of the two, however, it | |
493 | is not currently used for reaching definitions. */ | |
494 | static sbitmap u_bitmap; | |
495 | ||
496 | /* Each block has a bitmap of each type. | |
497 | The length of each blocks bitmap is: | |
498 | ||
499 | max_cuid - for reaching definitions | |
500 | n_exprs - for available expressions | |
501 | ||
502 | Thus we view the bitmaps as 2 dimensional arrays. i.e. | |
503 | rd_kill[block_num][cuid_num] | |
504 | ae_kill[block_num][expr_num] | |
505 | */ | |
506 | ||
507 | /* For reaching defs */ | |
508 | static sbitmap *rd_kill, *rd_gen, *reaching_defs, *rd_out; | |
509 | ||
510 | /* for available exprs */ | |
511 | static sbitmap *ae_kill, *ae_gen, *ae_in, *ae_out; | |
b5ce41ff | 512 | |
0511851c MM |
513 | /* Objects of this type are passed around by the null-pointer check |
514 | removal routines. */ | |
515 | struct null_pointer_info { | |
516 | /* The basic block being processed. */ | |
517 | int current_block; | |
518 | /* The first register to be handled in this pass. */ | |
519 | int min_reg; | |
520 | /* One greater than the last register to be handled in this pass. */ | |
521 | int max_reg; | |
522 | sbitmap *nonnull_local; | |
523 | sbitmap *nonnull_killed; | |
524 | }; | |
7506f491 | 525 | \f |
ac7c5af5 JL |
526 | static void compute_can_copy PROTO ((void)); |
527 | ||
528 | static char *gmalloc PROTO ((unsigned int)); | |
529 | static char *grealloc PROTO ((char *, unsigned int)); | |
530 | static char *gcse_alloc PROTO ((unsigned long)); | |
531 | static void alloc_gcse_mem PROTO ((rtx)); | |
532 | static void free_gcse_mem PROTO ((void)); | |
ac7c5af5 JL |
533 | static void alloc_reg_set_mem PROTO ((int)); |
534 | static void free_reg_set_mem PROTO ((void)); | |
0511851c | 535 | static int get_bitmap_width PROTO ((int, int, int)); |
ac7c5af5 | 536 | static void record_one_set PROTO ((int, rtx)); |
84832317 | 537 | static void record_set_info PROTO ((rtx, rtx, void *)); |
ac7c5af5 JL |
538 | static void compute_sets PROTO ((rtx)); |
539 | ||
540 | static void hash_scan_insn PROTO ((rtx, int, int)); | |
541 | static void hash_scan_set PROTO ((rtx, rtx, int)); | |
542 | static void hash_scan_clobber PROTO ((rtx, rtx)); | |
543 | static void hash_scan_call PROTO ((rtx, rtx)); | |
ac7c5af5 JL |
544 | static int want_to_gcse_p PROTO ((rtx)); |
545 | static int oprs_unchanged_p PROTO ((rtx, rtx, int)); | |
7506f491 | 546 | static int oprs_anticipatable_p PROTO ((rtx, rtx)); |
ac7c5af5 | 547 | static int oprs_available_p PROTO ((rtx, rtx)); |
b5ce41ff JL |
548 | static void insert_expr_in_table PROTO ((rtx, enum machine_mode, |
549 | rtx, int, int)); | |
7506f491 | 550 | static void insert_set_in_table PROTO ((rtx, rtx)); |
b5ce41ff JL |
551 | static unsigned int hash_expr PROTO ((rtx, enum machine_mode, |
552 | int *, int)); | |
7506f491 | 553 | static unsigned int hash_expr_1 PROTO ((rtx, enum machine_mode, int *)); |
ac7c5af5 JL |
554 | static unsigned int hash_set PROTO ((int, int)); |
555 | static int expr_equiv_p PROTO ((rtx, rtx)); | |
7506f491 DE |
556 | static void record_last_reg_set_info PROTO ((rtx, int)); |
557 | static void record_last_mem_set_info PROTO ((rtx)); | |
84832317 | 558 | static void record_last_set_info PROTO ((rtx, rtx, void *)); |
b5ce41ff | 559 | static void compute_hash_table PROTO ((int)); |
7506f491 DE |
560 | static void alloc_set_hash_table PROTO ((int)); |
561 | static void free_set_hash_table PROTO ((void)); | |
b5ce41ff | 562 | static void compute_set_hash_table PROTO ((void)); |
7506f491 DE |
563 | static void alloc_expr_hash_table PROTO ((int)); |
564 | static void free_expr_hash_table PROTO ((void)); | |
b5ce41ff | 565 | static void compute_expr_hash_table PROTO ((void)); |
a65f3558 JL |
566 | static void dump_hash_table PROTO ((FILE *, const char *, struct expr **, |
567 | int, int)); | |
7506f491 | 568 | static struct expr *lookup_expr PROTO ((rtx)); |
ac7c5af5 JL |
569 | static struct expr *lookup_set PROTO ((int, rtx)); |
570 | static struct expr *next_set PROTO ((int, struct expr *)); | |
7506f491 | 571 | static void reset_opr_set_tables PROTO ((void)); |
ac7c5af5 | 572 | static int oprs_not_set_p PROTO ((rtx, rtx)); |
b5ce41ff | 573 | static void mark_call PROTO ((rtx)); |
ac7c5af5 JL |
574 | static void mark_set PROTO ((rtx, rtx)); |
575 | static void mark_clobber PROTO ((rtx, rtx)); | |
576 | static void mark_oprs_set PROTO ((rtx)); | |
577 | ||
ac7c5af5 JL |
578 | static void alloc_cprop_mem PROTO ((int, int)); |
579 | static void free_cprop_mem PROTO ((void)); | |
ac7c5af5 | 580 | static void compute_transp PROTO ((rtx, int, sbitmap *, int)); |
a65f3558 | 581 | static void compute_transpout PROTO ((void)); |
b5ce41ff JL |
582 | static void compute_local_properties PROTO ((sbitmap *, sbitmap *, |
583 | sbitmap *, int)); | |
ac7c5af5 JL |
584 | static void compute_cprop_data PROTO ((void)); |
585 | static void find_used_regs PROTO ((rtx)); | |
586 | static int try_replace_reg PROTO ((rtx, rtx, rtx)); | |
7506f491 | 587 | static struct expr *find_avail_set PROTO ((int, rtx)); |
abd535b6 | 588 | static int cprop_jump PROTO((rtx, rtx, struct reg_use *, rtx)); |
e2bef702 | 589 | #ifdef HAVE_cc0 |
abd535b6 | 590 | static int cprop_cc0_jump PROTO((rtx, struct reg_use *, rtx)); |
e2bef702 | 591 | #endif |
b5ce41ff JL |
592 | static int cprop_insn PROTO ((rtx, int)); |
593 | static int cprop PROTO ((int)); | |
594 | static int one_cprop_pass PROTO ((int, int)); | |
7506f491 | 595 | |
ac7c5af5 JL |
596 | static void alloc_pre_mem PROTO ((int, int)); |
597 | static void free_pre_mem PROTO ((void)); | |
ac7c5af5 | 598 | static void compute_pre_data PROTO ((void)); |
89e606c9 | 599 | static int pre_expr_reaches_here_p PROTO ((int, struct expr *, int)); |
a65f3558 | 600 | static void insert_insn_end_bb PROTO ((struct expr *, int, int)); |
7506f491 | 601 | static void pre_insert_copy_insn PROTO ((struct expr *, rtx)); |
ac7c5af5 JL |
602 | static void pre_insert_copies PROTO ((void)); |
603 | static int pre_delete PROTO ((void)); | |
604 | static int pre_gcse PROTO ((void)); | |
b5ce41ff | 605 | static int one_pre_gcse_pass PROTO ((int)); |
aeb2f500 JW |
606 | |
607 | static void add_label_notes PROTO ((rtx, rtx)); | |
b5ce41ff | 608 | |
bb457bd9 JL |
609 | static void alloc_code_hoist_mem PROTO ((int, int)); |
610 | static void free_code_hoist_mem PROTO ((void)); | |
611 | static void compute_code_hoist_vbeinout PROTO ((void)); | |
612 | static void compute_code_hoist_data PROTO ((void)); | |
613 | static int hoist_expr_reaches_here_p PROTO ((int, int, int, char *)); | |
614 | static void hoist_code PROTO ((void)); | |
615 | static int one_code_hoisting_pass PROTO ((void)); | |
616 | ||
b5ce41ff JL |
617 | static void alloc_rd_mem PROTO ((int, int)); |
618 | static void free_rd_mem PROTO ((void)); | |
619 | static void handle_rd_kill_set PROTO ((rtx, int, int)); | |
620 | static void compute_kill_rd PROTO ((void)); | |
621 | static void compute_rd PROTO ((void)); | |
622 | static void alloc_avail_expr_mem PROTO ((int, int)); | |
623 | static void free_avail_expr_mem PROTO ((void)); | |
624 | static void compute_ae_gen PROTO ((void)); | |
625 | static int expr_killed_p PROTO ((rtx, int)); | |
a42cd965 | 626 | static void compute_ae_kill PROTO ((sbitmap *, sbitmap *)); |
b5ce41ff | 627 | static int expr_reaches_here_p PROTO ((struct occr *, struct expr *, |
283a2545 | 628 | int, int)); |
b5ce41ff JL |
629 | static rtx computing_insn PROTO ((struct expr *, rtx)); |
630 | static int def_reaches_here_p PROTO ((rtx, rtx)); | |
631 | static int can_disregard_other_sets PROTO ((struct reg_set **, rtx, int)); | |
632 | static int handle_avail_expr PROTO ((rtx, struct expr *)); | |
633 | static int classic_gcse PROTO ((void)); | |
634 | static int one_classic_gcse_pass PROTO ((int)); | |
84832317 | 635 | static void invalidate_nonnull_info PROTO ((rtx, rtx, void *)); |
b71a2ff8 | 636 | static void delete_null_pointer_checks_1 PROTO ((int *, sbitmap *, sbitmap *, |
0511851c | 637 | struct null_pointer_info *)); |
36f0e0a6 KG |
638 | static rtx process_insert_insn PROTO ((struct expr *)); |
639 | static int pre_edge_insert PROTO ((struct edge_list *, struct expr **)); | |
a8f227e7 | 640 | static int expr_reaches_here_p_work PROTO ((struct occr *, struct expr *, int, int, char *)); |
89e606c9 JL |
641 | static int pre_expr_reaches_here_p_work PROTO ((int, struct expr *, |
642 | int, char *)); | |
7506f491 DE |
643 | \f |
644 | /* Entry point for global common subexpression elimination. | |
645 | F is the first instruction in the function. */ | |
646 | ||
e78d9500 | 647 | int |
7506f491 DE |
648 | gcse_main (f, file) |
649 | rtx f; | |
650 | FILE *file; | |
651 | { | |
652 | int changed, pass; | |
653 | /* Bytes used at start of pass. */ | |
654 | int initial_bytes_used; | |
655 | /* Maximum number of bytes used by a pass. */ | |
656 | int max_pass_bytes; | |
657 | /* Point to release obstack data from for each pass. */ | |
658 | char *gcse_obstack_bottom; | |
659 | ||
b5ce41ff JL |
660 | /* We do not construct an accurate cfg in functions which call |
661 | setjmp, so just punt to be safe. */ | |
7506f491 | 662 | if (current_function_calls_setjmp) |
e78d9500 | 663 | return 0; |
7506f491 | 664 | |
b5ce41ff JL |
665 | /* Assume that we do not need to run jump optimizations after gcse. */ |
666 | run_jump_opt_after_gcse = 0; | |
667 | ||
7506f491 DE |
668 | /* For calling dump_foo fns from gdb. */ |
669 | debug_stderr = stderr; | |
b5ce41ff | 670 | gcse_file = file; |
7506f491 | 671 | |
b5ce41ff JL |
672 | /* Identify the basic block information for this function, including |
673 | successors and predecessors. */ | |
7506f491 | 674 | max_gcse_regno = max_reg_num (); |
359da67d | 675 | find_basic_blocks (f, max_gcse_regno, file, 1); |
7506f491 | 676 | |
a42cd965 AM |
677 | if (file) |
678 | dump_flow_info (file); | |
679 | ||
7506f491 DE |
680 | /* Return if there's nothing to do. */ |
681 | if (n_basic_blocks <= 1) | |
682 | { | |
683 | /* Free storage allocated by find_basic_blocks. */ | |
684 | free_basic_block_vars (0); | |
e78d9500 | 685 | return 0; |
7506f491 DE |
686 | } |
687 | ||
55f7891b JL |
688 | /* Trying to perform global optimizations on flow graphs which have |
689 | a high connectivity will take a long time and is unlikely to be | |
690 | particularly useful. | |
691 | ||
692 | In normal circumstances a cfg should have about twice has many edges | |
693 | as blocks. But we do not want to punish small functions which have | |
694 | a couple switch statements. So we require a relatively large number | |
695 | of basic blocks and the ratio of edges to blocks to be high. */ | |
696 | if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20) | |
697 | { | |
698 | /* Free storage allocated by find_basic_blocks. */ | |
699 | free_basic_block_vars (0); | |
700 | return 0; | |
701 | } | |
702 | ||
7506f491 DE |
703 | /* See what modes support reg/reg copy operations. */ |
704 | if (! can_copy_init_p) | |
705 | { | |
706 | compute_can_copy (); | |
707 | can_copy_init_p = 1; | |
708 | } | |
709 | ||
710 | gcc_obstack_init (&gcse_obstack); | |
a42cd965 | 711 | bytes_used = 0; |
7506f491 DE |
712 | |
713 | /* Record where pseudo-registers are set. | |
714 | This data is kept accurate during each pass. | |
b5ce41ff | 715 | ??? We could also record hard-reg information here |
7506f491 | 716 | [since it's unchanging], however it is currently done during |
b5ce41ff JL |
717 | hash table computation. |
718 | ||
719 | It may be tempting to compute MEM set information here too, but MEM | |
720 | sets will be subject to code motion one day and thus we need to compute | |
721 | information about memory sets when we build the hash tables. */ | |
7506f491 DE |
722 | |
723 | alloc_reg_set_mem (max_gcse_regno); | |
724 | compute_sets (f); | |
725 | ||
726 | pass = 0; | |
727 | initial_bytes_used = bytes_used; | |
728 | max_pass_bytes = 0; | |
729 | gcse_obstack_bottom = gcse_alloc (1); | |
730 | changed = 1; | |
731 | while (changed && pass < MAX_PASSES) | |
732 | { | |
733 | changed = 0; | |
734 | if (file) | |
735 | fprintf (file, "GCSE pass %d\n\n", pass + 1); | |
736 | ||
737 | /* Initialize bytes_used to the space for the pred/succ lists, | |
738 | and the reg_set_table data. */ | |
739 | bytes_used = initial_bytes_used; | |
740 | ||
741 | /* Each pass may create new registers, so recalculate each time. */ | |
742 | max_gcse_regno = max_reg_num (); | |
743 | ||
744 | alloc_gcse_mem (f); | |
745 | ||
b5ce41ff JL |
746 | /* Don't allow constant propagation to modify jumps |
747 | during this pass. */ | |
748 | changed = one_cprop_pass (pass + 1, 0); | |
7506f491 DE |
749 | |
750 | if (optimize_size) | |
b5ce41ff | 751 | changed |= one_classic_gcse_pass (pass + 1); |
7506f491 | 752 | else |
a42cd965 AM |
753 | { |
754 | changed |= one_pre_gcse_pass (pass + 1); | |
755 | free_reg_set_mem (); | |
756 | alloc_reg_set_mem (max_reg_num ()); | |
757 | compute_sets (f); | |
758 | run_jump_opt_after_gcse = 1; | |
759 | } | |
7506f491 DE |
760 | |
761 | if (max_pass_bytes < bytes_used) | |
762 | max_pass_bytes = bytes_used; | |
763 | ||
bb457bd9 JL |
764 | /* Free up memory, then reallocate for code hoisting. We can |
765 | not re-use the existing allocated memory because the tables | |
766 | will not have info for the insns or registers created by | |
767 | partial redundancy elimination. */ | |
7506f491 DE |
768 | free_gcse_mem (); |
769 | ||
bb457bd9 JL |
770 | /* It does not make sense to run code hoisting unless we optimizing |
771 | for code size -- it rarely makes programs faster, and can make | |
772 | them bigger if we did partial redundancy elimination (when optimizing | |
773 | for space, we use a classic gcse algorithm instead of partial | |
774 | redundancy algorithms). */ | |
775 | if (optimize_size) | |
776 | { | |
777 | max_gcse_regno = max_reg_num (); | |
778 | alloc_gcse_mem (f); | |
779 | changed |= one_code_hoisting_pass (); | |
780 | free_gcse_mem (); | |
781 | ||
782 | if (max_pass_bytes < bytes_used) | |
783 | max_pass_bytes = bytes_used; | |
784 | } | |
785 | ||
7506f491 DE |
786 | if (file) |
787 | { | |
788 | fprintf (file, "\n"); | |
789 | fflush (file); | |
790 | } | |
791 | obstack_free (&gcse_obstack, gcse_obstack_bottom); | |
792 | pass++; | |
793 | } | |
794 | ||
b5ce41ff JL |
795 | /* Do one last pass of copy propagation, including cprop into |
796 | conditional jumps. */ | |
797 | ||
798 | max_gcse_regno = max_reg_num (); | |
799 | alloc_gcse_mem (f); | |
800 | /* This time, go ahead and allow cprop to alter jumps. */ | |
801 | one_cprop_pass (pass + 1, 1); | |
802 | free_gcse_mem (); | |
7506f491 DE |
803 | |
804 | if (file) | |
805 | { | |
806 | fprintf (file, "GCSE of %s: %d basic blocks, ", | |
807 | current_function_name, n_basic_blocks); | |
808 | fprintf (file, "%d pass%s, %d bytes\n\n", | |
809 | pass, pass > 1 ? "es" : "", max_pass_bytes); | |
810 | } | |
811 | ||
812 | /* Free our obstack. */ | |
813 | obstack_free (&gcse_obstack, NULL_PTR); | |
814 | /* Free reg_set_table. */ | |
815 | free_reg_set_mem (); | |
7506f491 DE |
816 | /* Free storage allocated by find_basic_blocks. */ |
817 | free_basic_block_vars (0); | |
e78d9500 | 818 | return run_jump_opt_after_gcse; |
7506f491 DE |
819 | } |
820 | \f | |
821 | /* Misc. utilities. */ | |
822 | ||
823 | /* Compute which modes support reg/reg copy operations. */ | |
824 | ||
825 | static void | |
826 | compute_can_copy () | |
827 | { | |
828 | int i; | |
50b2596f | 829 | #ifndef AVOID_CCMODE_COPIES |
7506f491 | 830 | rtx reg,insn; |
50b2596f | 831 | #endif |
7506f491 DE |
832 | char *free_point = (char *) oballoc (1); |
833 | ||
834 | bzero (can_copy_p, NUM_MACHINE_MODES); | |
835 | ||
836 | start_sequence (); | |
837 | for (i = 0; i < NUM_MACHINE_MODES; i++) | |
838 | { | |
839 | switch (GET_MODE_CLASS (i)) | |
840 | { | |
841 | case MODE_CC : | |
842 | #ifdef AVOID_CCMODE_COPIES | |
843 | can_copy_p[i] = 0; | |
844 | #else | |
9e6a5703 JC |
845 | reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1); |
846 | insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg)); | |
7506f491 DE |
847 | if (recog (PATTERN (insn), insn, NULL_PTR) >= 0) |
848 | can_copy_p[i] = 1; | |
849 | #endif | |
850 | break; | |
851 | default : | |
852 | can_copy_p[i] = 1; | |
853 | break; | |
854 | } | |
855 | } | |
856 | end_sequence (); | |
857 | ||
858 | /* Free the objects we just allocated. */ | |
859 | obfree (free_point); | |
860 | } | |
861 | \f | |
862 | /* Cover function to xmalloc to record bytes allocated. */ | |
863 | ||
864 | static char * | |
865 | gmalloc (size) | |
866 | unsigned int size; | |
867 | { | |
868 | bytes_used += size; | |
869 | return xmalloc (size); | |
870 | } | |
871 | ||
872 | /* Cover function to xrealloc. | |
873 | We don't record the additional size since we don't know it. | |
874 | It won't affect memory usage stats much anyway. */ | |
875 | ||
876 | static char * | |
877 | grealloc (ptr, size) | |
878 | char *ptr; | |
879 | unsigned int size; | |
880 | { | |
881 | return xrealloc (ptr, size); | |
882 | } | |
883 | ||
884 | /* Cover function to obstack_alloc. | |
885 | We don't need to record the bytes allocated here since | |
886 | obstack_chunk_alloc is set to gmalloc. */ | |
887 | ||
888 | static char * | |
889 | gcse_alloc (size) | |
890 | unsigned long size; | |
891 | { | |
892 | return (char *) obstack_alloc (&gcse_obstack, size); | |
893 | } | |
894 | ||
895 | /* Allocate memory for the cuid mapping array, | |
896 | and reg/memory set tracking tables. | |
897 | ||
898 | This is called at the start of each pass. */ | |
899 | ||
900 | static void | |
901 | alloc_gcse_mem (f) | |
902 | rtx f; | |
903 | { | |
904 | int i,n; | |
905 | rtx insn; | |
906 | ||
907 | /* Find the largest UID and create a mapping from UIDs to CUIDs. | |
908 | CUIDs are like UIDs except they increase monotonically, have no gaps, | |
909 | and only apply to real insns. */ | |
910 | ||
911 | max_uid = get_max_uid (); | |
912 | n = (max_uid + 1) * sizeof (int); | |
913 | uid_cuid = (int *) gmalloc (n); | |
914 | bzero ((char *) uid_cuid, n); | |
915 | for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) | |
916 | { | |
917 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
918 | INSN_CUID (insn) = i++; | |
919 | else | |
920 | INSN_CUID (insn) = i; | |
921 | } | |
922 | ||
923 | /* Create a table mapping cuids to insns. */ | |
924 | ||
925 | max_cuid = i; | |
926 | n = (max_cuid + 1) * sizeof (rtx); | |
927 | cuid_insn = (rtx *) gmalloc (n); | |
928 | bzero ((char *) cuid_insn, n); | |
929 | for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) | |
930 | { | |
931 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
932 | { | |
933 | CUID_INSN (i) = insn; | |
934 | i++; | |
935 | } | |
936 | } | |
937 | ||
938 | /* Allocate vars to track sets of regs. */ | |
939 | ||
940 | reg_set_bitmap = (sbitmap) sbitmap_alloc (max_gcse_regno); | |
941 | ||
942 | /* Allocate vars to track sets of regs, memory per block. */ | |
943 | ||
944 | reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (n_basic_blocks, | |
945 | max_gcse_regno); | |
946 | mem_set_in_block = (char *) gmalloc (n_basic_blocks); | |
947 | } | |
948 | ||
949 | /* Free memory allocated by alloc_gcse_mem. */ | |
950 | ||
951 | static void | |
952 | free_gcse_mem () | |
953 | { | |
954 | free (uid_cuid); | |
955 | free (cuid_insn); | |
956 | ||
957 | free (reg_set_bitmap); | |
958 | ||
959 | free (reg_set_in_block); | |
960 | free (mem_set_in_block); | |
961 | } | |
962 | ||
0511851c MM |
963 | /* Many of the global optimization algorithms work by solving dataflow |
964 | equations for various expressions. Initially, some local value is | |
965 | computed for each expression in each block. Then, the values | |
966 | across the various blocks are combined (by following flow graph | |
967 | edges) to arrive at global values. Conceptually, each set of | |
968 | equations is independent. We may therefore solve all the equations | |
969 | in parallel, solve them one at a time, or pick any intermediate | |
970 | approach. | |
971 | ||
972 | When you're going to need N two-dimensional bitmaps, each X (say, | |
973 | the number of blocks) by Y (say, the number of expressions), call | |
974 | this function. It's not important what X and Y represent; only | |
975 | that Y correspond to the things that can be done in parallel. This | |
976 | function will return an appropriate chunking factor C; you should | |
977 | solve C sets of equations in parallel. By going through this | |
978 | function, we can easily trade space against time; by solving fewer | |
979 | equations in parallel we use less space. */ | |
980 | ||
981 | static int | |
982 | get_bitmap_width (n, x, y) | |
983 | int n; | |
984 | int x; | |
985 | int y; | |
986 | { | |
987 | /* It's not really worth figuring out *exactly* how much memory will | |
988 | be used by a particular choice. The important thing is to get | |
989 | something approximately right. */ | |
990 | size_t max_bitmap_memory = 10 * 1024 * 1024; | |
991 | ||
992 | /* The number of bytes we'd use for a single column of minimum | |
993 | width. */ | |
994 | size_t column_size = n * x * sizeof (SBITMAP_ELT_TYPE); | |
995 | ||
996 | /* Often, it's reasonable just to solve all the equations in | |
997 | parallel. */ | |
998 | if (column_size * SBITMAP_SET_SIZE (y) <= max_bitmap_memory) | |
999 | return y; | |
1000 | ||
1001 | /* Otherwise, pick the largest width we can, without going over the | |
1002 | limit. */ | |
1003 | return SBITMAP_ELT_BITS * ((max_bitmap_memory + column_size - 1) | |
1004 | / column_size); | |
1005 | } | |
1006 | ||
b5ce41ff JL |
1007 | \f |
1008 | /* Compute the local properties of each recorded expression. | |
1009 | Local properties are those that are defined by the block, irrespective | |
1010 | of other blocks. | |
1011 | ||
1012 | An expression is transparent in a block if its operands are not modified | |
1013 | in the block. | |
1014 | ||
1015 | An expression is computed (locally available) in a block if it is computed | |
1016 | at least once and expression would contain the same value if the | |
1017 | computation was moved to the end of the block. | |
1018 | ||
1019 | An expression is locally anticipatable in a block if it is computed at | |
1020 | least once and expression would contain the same value if the computation | |
1021 | was moved to the beginning of the block. | |
1022 | ||
1023 | We call this routine for cprop, pre and code hoisting. They all | |
1024 | compute basically the same information and thus can easily share | |
1025 | this code. | |
7506f491 | 1026 | |
b5ce41ff JL |
1027 | TRANSP, COMP, and ANTLOC are destination sbitmaps for recording |
1028 | local properties. If NULL, then it is not necessary to compute | |
1029 | or record that particular property. | |
1030 | ||
1031 | SETP controls which hash table to look at. If zero, this routine | |
1032 | looks at the expr hash table; if nonzero this routine looks at | |
695ab36a BS |
1033 | the set hash table. Additionally, TRANSP is computed as ~TRANSP, |
1034 | since this is really cprop's ABSALTERED. */ | |
b5ce41ff JL |
1035 | |
1036 | static void | |
1037 | compute_local_properties (transp, comp, antloc, setp) | |
1038 | sbitmap *transp; | |
1039 | sbitmap *comp; | |
1040 | sbitmap *antloc; | |
1041 | int setp; | |
1042 | { | |
1043 | int i, hash_table_size; | |
1044 | struct expr **hash_table; | |
1045 | ||
1046 | /* Initialize any bitmaps that were passed in. */ | |
1047 | if (transp) | |
695ab36a BS |
1048 | { |
1049 | if (setp) | |
1050 | sbitmap_vector_zero (transp, n_basic_blocks); | |
1051 | else | |
1052 | sbitmap_vector_ones (transp, n_basic_blocks); | |
1053 | } | |
b5ce41ff JL |
1054 | if (comp) |
1055 | sbitmap_vector_zero (comp, n_basic_blocks); | |
1056 | if (antloc) | |
1057 | sbitmap_vector_zero (antloc, n_basic_blocks); | |
1058 | ||
1059 | /* We use the same code for cprop, pre and hoisting. For cprop | |
1060 | we care about the set hash table, for pre and hoisting we | |
1061 | care about the expr hash table. */ | |
1062 | hash_table_size = setp ? set_hash_table_size : expr_hash_table_size; | |
1063 | hash_table = setp ? set_hash_table : expr_hash_table; | |
1064 | ||
1065 | for (i = 0; i < hash_table_size; i++) | |
7506f491 | 1066 | { |
b5ce41ff JL |
1067 | struct expr *expr; |
1068 | ||
1069 | for (expr = hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
1070 | { | |
1071 | struct occr *occr; | |
1072 | int indx = expr->bitmap_index; | |
1073 | ||
1074 | /* The expression is transparent in this block if it is not killed. | |
1075 | We start by assuming all are transparent [none are killed], and | |
1076 | then reset the bits for those that are. */ | |
1077 | ||
1078 | if (transp) | |
1079 | compute_transp (expr->expr, indx, transp, setp); | |
1080 | ||
1081 | /* The occurrences recorded in antic_occr are exactly those that | |
1082 | we want to set to non-zero in ANTLOC. */ | |
1083 | ||
1084 | if (antloc) | |
1085 | { | |
1086 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
1087 | { | |
1088 | int bb = BLOCK_NUM (occr->insn); | |
1089 | SET_BIT (antloc[bb], indx); | |
1090 | ||
1091 | /* While we're scanning the table, this is a good place to | |
1092 | initialize this. */ | |
1093 | occr->deleted_p = 0; | |
1094 | } | |
1095 | } | |
1096 | ||
1097 | /* The occurrences recorded in avail_occr are exactly those that | |
1098 | we want to set to non-zero in COMP. */ | |
1099 | if (comp) | |
1100 | { | |
1101 | ||
1102 | for (occr = expr->avail_occr; occr != NULL; occr = occr->next) | |
1103 | { | |
1104 | int bb = BLOCK_NUM (occr->insn); | |
1105 | SET_BIT (comp[bb], indx); | |
1106 | ||
1107 | /* While we're scanning the table, this is a good place to | |
1108 | initialize this. */ | |
1109 | occr->copied_p = 0; | |
1110 | } | |
1111 | } | |
1112 | ||
1113 | /* While we're scanning the table, this is a good place to | |
1114 | initialize this. */ | |
1115 | expr->reaching_reg = 0; | |
1116 | } | |
7506f491 | 1117 | } |
7506f491 | 1118 | } |
b5ce41ff | 1119 | |
7506f491 DE |
1120 | \f |
1121 | /* Register set information. | |
1122 | ||
1123 | `reg_set_table' records where each register is set or otherwise | |
1124 | modified. */ | |
1125 | ||
1126 | static struct obstack reg_set_obstack; | |
1127 | ||
1128 | static void | |
1129 | alloc_reg_set_mem (n_regs) | |
1130 | int n_regs; | |
1131 | { | |
1132 | int n; | |
1133 | ||
1134 | reg_set_table_size = n_regs + REG_SET_TABLE_SLOP; | |
1135 | n = reg_set_table_size * sizeof (struct reg_set *); | |
1136 | reg_set_table = (struct reg_set **) gmalloc (n); | |
1137 | bzero ((char *) reg_set_table, n); | |
1138 | ||
1139 | gcc_obstack_init (®_set_obstack); | |
1140 | } | |
1141 | ||
1142 | static void | |
1143 | free_reg_set_mem () | |
1144 | { | |
1145 | free (reg_set_table); | |
1146 | obstack_free (®_set_obstack, NULL_PTR); | |
1147 | } | |
1148 | ||
1149 | /* Record REGNO in the reg_set table. */ | |
1150 | ||
1151 | static void | |
1152 | record_one_set (regno, insn) | |
1153 | int regno; | |
1154 | rtx insn; | |
1155 | { | |
1156 | /* allocate a new reg_set element and link it onto the list */ | |
1157 | struct reg_set *new_reg_info, *reg_info_ptr1, *reg_info_ptr2; | |
1158 | ||
1159 | /* If the table isn't big enough, enlarge it. */ | |
1160 | if (regno >= reg_set_table_size) | |
1161 | { | |
1162 | int new_size = regno + REG_SET_TABLE_SLOP; | |
1163 | reg_set_table = (struct reg_set **) | |
1164 | grealloc ((char *) reg_set_table, | |
1165 | new_size * sizeof (struct reg_set *)); | |
1166 | bzero ((char *) (reg_set_table + reg_set_table_size), | |
1167 | (new_size - reg_set_table_size) * sizeof (struct reg_set *)); | |
1168 | reg_set_table_size = new_size; | |
1169 | } | |
1170 | ||
1171 | new_reg_info = (struct reg_set *) obstack_alloc (®_set_obstack, | |
1172 | sizeof (struct reg_set)); | |
1173 | bytes_used += sizeof (struct reg_set); | |
1174 | new_reg_info->insn = insn; | |
1175 | new_reg_info->next = NULL; | |
1176 | if (reg_set_table[regno] == NULL) | |
1177 | reg_set_table[regno] = new_reg_info; | |
1178 | else | |
1179 | { | |
1180 | reg_info_ptr1 = reg_info_ptr2 = reg_set_table[regno]; | |
1181 | /* ??? One could keep a "last" pointer to speed this up. */ | |
1182 | while (reg_info_ptr1 != NULL) | |
1183 | { | |
1184 | reg_info_ptr2 = reg_info_ptr1; | |
1185 | reg_info_ptr1 = reg_info_ptr1->next; | |
1186 | } | |
1187 | reg_info_ptr2->next = new_reg_info; | |
1188 | } | |
1189 | } | |
1190 | ||
7506f491 | 1191 | /* Called from compute_sets via note_stores to handle one |
84832317 MM |
1192 | SET or CLOBBER in an insn. The DATA is really the instruction |
1193 | in which the SET is occurring. */ | |
7506f491 DE |
1194 | |
1195 | static void | |
84832317 | 1196 | record_set_info (dest, setter, data) |
50b2596f | 1197 | rtx dest, setter ATTRIBUTE_UNUSED; |
84832317 | 1198 | void *data; |
7506f491 | 1199 | { |
84832317 MM |
1200 | rtx record_set_insn = (rtx) data; |
1201 | ||
7506f491 DE |
1202 | if (GET_CODE (dest) == SUBREG) |
1203 | dest = SUBREG_REG (dest); | |
1204 | ||
1205 | if (GET_CODE (dest) == REG) | |
1206 | { | |
1207 | if (REGNO (dest) >= FIRST_PSEUDO_REGISTER) | |
1208 | record_one_set (REGNO (dest), record_set_insn); | |
1209 | } | |
1210 | } | |
1211 | ||
1212 | /* Scan the function and record each set of each pseudo-register. | |
1213 | ||
1214 | This is called once, at the start of the gcse pass. | |
1215 | See the comments for `reg_set_table' for further docs. */ | |
1216 | ||
1217 | static void | |
1218 | compute_sets (f) | |
1219 | rtx f; | |
1220 | { | |
1221 | rtx insn = f; | |
1222 | ||
1223 | while (insn) | |
1224 | { | |
1225 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
84832317 | 1226 | note_stores (PATTERN (insn), record_set_info, insn); |
7506f491 DE |
1227 | insn = NEXT_INSN (insn); |
1228 | } | |
1229 | } | |
1230 | \f | |
1231 | /* Hash table support. */ | |
1232 | ||
b86ba9c8 GK |
1233 | #define NEVER_SET -1 |
1234 | ||
7506f491 | 1235 | /* For each register, the cuid of the first/last insn in the block to set it, |
e7d99f1e | 1236 | or -1 if not set. */ |
7506f491 DE |
1237 | static int *reg_first_set; |
1238 | static int *reg_last_set; | |
1239 | ||
1240 | /* While computing "first/last set" info, this is the CUID of first/last insn | |
e7d99f1e | 1241 | to set memory or -1 if not set. `mem_last_set' is also used when |
7506f491 DE |
1242 | performing GCSE to record whether memory has been set since the beginning |
1243 | of the block. | |
1244 | Note that handling of memory is very simple, we don't make any attempt | |
1245 | to optimize things (later). */ | |
1246 | static int mem_first_set; | |
1247 | static int mem_last_set; | |
1248 | ||
7506f491 DE |
1249 | /* Perform a quick check whether X, the source of a set, is something |
1250 | we want to consider for GCSE. */ | |
1251 | ||
1252 | static int | |
1253 | want_to_gcse_p (x) | |
1254 | rtx x; | |
1255 | { | |
1256 | enum rtx_code code = GET_CODE (x); | |
1257 | ||
1258 | switch (code) | |
1259 | { | |
1260 | case REG: | |
1261 | case SUBREG: | |
1262 | case CONST_INT: | |
1263 | case CONST_DOUBLE: | |
1264 | case CALL: | |
1265 | return 0; | |
1266 | ||
1267 | default: | |
1268 | break; | |
1269 | } | |
1270 | ||
1271 | return 1; | |
1272 | } | |
1273 | ||
1274 | /* Return non-zero if the operands of expression X are unchanged from the | |
1275 | start of INSN's basic block up to but not including INSN (if AVAIL_P == 0), | |
1276 | or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */ | |
1277 | ||
1278 | static int | |
1279 | oprs_unchanged_p (x, insn, avail_p) | |
1280 | rtx x, insn; | |
1281 | int avail_p; | |
1282 | { | |
1283 | int i; | |
1284 | enum rtx_code code; | |
6f7d635c | 1285 | const char *fmt; |
7506f491 DE |
1286 | |
1287 | /* repeat is used to turn tail-recursion into iteration. */ | |
1288 | repeat: | |
1289 | ||
1290 | if (x == 0) | |
1291 | return 1; | |
1292 | ||
1293 | code = GET_CODE (x); | |
1294 | switch (code) | |
1295 | { | |
1296 | case REG: | |
1297 | if (avail_p) | |
b86ba9c8 | 1298 | return (reg_last_set[REGNO (x)] == NEVER_SET |
7506f491 DE |
1299 | || reg_last_set[REGNO (x)] < INSN_CUID (insn)); |
1300 | else | |
b86ba9c8 | 1301 | return (reg_first_set[REGNO (x)] == NEVER_SET |
7506f491 DE |
1302 | || reg_first_set[REGNO (x)] >= INSN_CUID (insn)); |
1303 | ||
1304 | case MEM: | |
1305 | if (avail_p) | |
1306 | { | |
b86ba9c8 | 1307 | if (mem_last_set != NEVER_SET |
7506f491 DE |
1308 | && mem_last_set >= INSN_CUID (insn)) |
1309 | return 0; | |
1310 | } | |
1311 | else | |
1312 | { | |
b86ba9c8 | 1313 | if (mem_first_set != NEVER_SET |
7506f491 DE |
1314 | && mem_first_set < INSN_CUID (insn)) |
1315 | return 0; | |
1316 | } | |
1317 | x = XEXP (x, 0); | |
1318 | goto repeat; | |
1319 | ||
1320 | case PRE_DEC: | |
1321 | case PRE_INC: | |
1322 | case POST_DEC: | |
1323 | case POST_INC: | |
1324 | return 0; | |
1325 | ||
1326 | case PC: | |
1327 | case CC0: /*FIXME*/ | |
1328 | case CONST: | |
1329 | case CONST_INT: | |
1330 | case CONST_DOUBLE: | |
1331 | case SYMBOL_REF: | |
1332 | case LABEL_REF: | |
1333 | case ADDR_VEC: | |
1334 | case ADDR_DIFF_VEC: | |
1335 | return 1; | |
1336 | ||
1337 | default: | |
1338 | break; | |
1339 | } | |
1340 | ||
1341 | i = GET_RTX_LENGTH (code) - 1; | |
1342 | fmt = GET_RTX_FORMAT (code); | |
1343 | for (; i >= 0; i--) | |
1344 | { | |
1345 | if (fmt[i] == 'e') | |
1346 | { | |
1347 | rtx tem = XEXP (x, i); | |
1348 | ||
1349 | /* If we are about to do the last recursive call | |
1350 | needed at this level, change it into iteration. | |
1351 | This function is called enough to be worth it. */ | |
1352 | if (i == 0) | |
1353 | { | |
1354 | x = tem; | |
1355 | goto repeat; | |
1356 | } | |
1357 | if (! oprs_unchanged_p (tem, insn, avail_p)) | |
1358 | return 0; | |
1359 | } | |
1360 | else if (fmt[i] == 'E') | |
1361 | { | |
1362 | int j; | |
1363 | for (j = 0; j < XVECLEN (x, i); j++) | |
1364 | { | |
1365 | if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p)) | |
1366 | return 0; | |
1367 | } | |
1368 | } | |
1369 | } | |
1370 | ||
1371 | return 1; | |
1372 | } | |
1373 | ||
1374 | /* Return non-zero if the operands of expression X are unchanged from | |
1375 | the start of INSN's basic block up to but not including INSN. */ | |
1376 | ||
1377 | static int | |
1378 | oprs_anticipatable_p (x, insn) | |
1379 | rtx x, insn; | |
1380 | { | |
1381 | return oprs_unchanged_p (x, insn, 0); | |
1382 | } | |
1383 | ||
1384 | /* Return non-zero if the operands of expression X are unchanged from | |
1385 | INSN to the end of INSN's basic block. */ | |
1386 | ||
1387 | static int | |
1388 | oprs_available_p (x, insn) | |
1389 | rtx x, insn; | |
1390 | { | |
1391 | return oprs_unchanged_p (x, insn, 1); | |
1392 | } | |
1393 | ||
1394 | /* Hash expression X. | |
1395 | MODE is only used if X is a CONST_INT. | |
1396 | A boolean indicating if a volatile operand is found or if the expression | |
1397 | contains something we don't want to insert in the table is stored in | |
1398 | DO_NOT_RECORD_P. | |
1399 | ||
1400 | ??? One might want to merge this with canon_hash. Later. */ | |
1401 | ||
1402 | static unsigned int | |
1403 | hash_expr (x, mode, do_not_record_p, hash_table_size) | |
1404 | rtx x; | |
1405 | enum machine_mode mode; | |
1406 | int *do_not_record_p; | |
1407 | int hash_table_size; | |
1408 | { | |
1409 | unsigned int hash; | |
1410 | ||
1411 | *do_not_record_p = 0; | |
1412 | ||
1413 | hash = hash_expr_1 (x, mode, do_not_record_p); | |
1414 | return hash % hash_table_size; | |
1415 | } | |
1416 | ||
1417 | /* Subroutine of hash_expr to do the actual work. */ | |
1418 | ||
1419 | static unsigned int | |
1420 | hash_expr_1 (x, mode, do_not_record_p) | |
1421 | rtx x; | |
1422 | enum machine_mode mode; | |
1423 | int *do_not_record_p; | |
1424 | { | |
1425 | int i, j; | |
1426 | unsigned hash = 0; | |
1427 | enum rtx_code code; | |
6f7d635c | 1428 | const char *fmt; |
7506f491 DE |
1429 | |
1430 | /* repeat is used to turn tail-recursion into iteration. */ | |
1431 | repeat: | |
1432 | ||
1433 | if (x == 0) | |
1434 | return hash; | |
1435 | ||
1436 | code = GET_CODE (x); | |
1437 | switch (code) | |
1438 | { | |
1439 | case REG: | |
1440 | { | |
1441 | register int regno = REGNO (x); | |
1442 | hash += ((unsigned) REG << 7) + regno; | |
1443 | return hash; | |
1444 | } | |
1445 | ||
1446 | case CONST_INT: | |
1447 | { | |
1448 | unsigned HOST_WIDE_INT tem = INTVAL (x); | |
1449 | hash += ((unsigned) CONST_INT << 7) + (unsigned) mode + tem; | |
1450 | return hash; | |
1451 | } | |
1452 | ||
1453 | case CONST_DOUBLE: | |
1454 | /* This is like the general case, except that it only counts | |
1455 | the integers representing the constant. */ | |
1456 | hash += (unsigned) code + (unsigned) GET_MODE (x); | |
1457 | if (GET_MODE (x) != VOIDmode) | |
1458 | for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++) | |
1459 | { | |
8a34409d | 1460 | unsigned tem = XWINT (x, i); |
7506f491 DE |
1461 | hash += tem; |
1462 | } | |
1463 | else | |
1464 | hash += ((unsigned) CONST_DOUBLE_LOW (x) | |
1465 | + (unsigned) CONST_DOUBLE_HIGH (x)); | |
1466 | return hash; | |
1467 | ||
1468 | /* Assume there is only one rtx object for any given label. */ | |
1469 | case LABEL_REF: | |
1470 | /* We don't hash on the address of the CODE_LABEL to avoid bootstrap | |
1471 | differences and differences between each stage's debugging dumps. */ | |
1472 | hash += ((unsigned) LABEL_REF << 7) + CODE_LABEL_NUMBER (XEXP (x, 0)); | |
1473 | return hash; | |
1474 | ||
1475 | case SYMBOL_REF: | |
1476 | { | |
1477 | /* Don't hash on the symbol's address to avoid bootstrap differences. | |
1478 | Different hash values may cause expressions to be recorded in | |
1479 | different orders and thus different registers to be used in the | |
1480 | final assembler. This also avoids differences in the dump files | |
1481 | between various stages. */ | |
1482 | unsigned int h = 0; | |
1483 | unsigned char *p = (unsigned char *) XSTR (x, 0); | |
1484 | while (*p) | |
1485 | h += (h << 7) + *p++; /* ??? revisit */ | |
1486 | hash += ((unsigned) SYMBOL_REF << 7) + h; | |
1487 | return hash; | |
1488 | } | |
1489 | ||
1490 | case MEM: | |
1491 | if (MEM_VOLATILE_P (x)) | |
1492 | { | |
1493 | *do_not_record_p = 1; | |
1494 | return 0; | |
1495 | } | |
1496 | hash += (unsigned) MEM; | |
297c3335 | 1497 | hash += MEM_ALIAS_SET (x); |
7506f491 DE |
1498 | x = XEXP (x, 0); |
1499 | goto repeat; | |
1500 | ||
1501 | case PRE_DEC: | |
1502 | case PRE_INC: | |
1503 | case POST_DEC: | |
1504 | case POST_INC: | |
1505 | case PC: | |
1506 | case CC0: | |
1507 | case CALL: | |
1508 | case UNSPEC_VOLATILE: | |
1509 | *do_not_record_p = 1; | |
1510 | return 0; | |
1511 | ||
1512 | case ASM_OPERANDS: | |
1513 | if (MEM_VOLATILE_P (x)) | |
1514 | { | |
1515 | *do_not_record_p = 1; | |
1516 | return 0; | |
1517 | } | |
1518 | ||
1519 | default: | |
1520 | break; | |
1521 | } | |
1522 | ||
1523 | i = GET_RTX_LENGTH (code) - 1; | |
1524 | hash += (unsigned) code + (unsigned) GET_MODE (x); | |
1525 | fmt = GET_RTX_FORMAT (code); | |
1526 | for (; i >= 0; i--) | |
1527 | { | |
1528 | if (fmt[i] == 'e') | |
1529 | { | |
1530 | rtx tem = XEXP (x, i); | |
1531 | ||
1532 | /* If we are about to do the last recursive call | |
1533 | needed at this level, change it into iteration. | |
1534 | This function is called enough to be worth it. */ | |
1535 | if (i == 0) | |
1536 | { | |
1537 | x = tem; | |
1538 | goto repeat; | |
1539 | } | |
1540 | hash += hash_expr_1 (tem, 0, do_not_record_p); | |
1541 | if (*do_not_record_p) | |
1542 | return 0; | |
1543 | } | |
1544 | else if (fmt[i] == 'E') | |
1545 | for (j = 0; j < XVECLEN (x, i); j++) | |
1546 | { | |
1547 | hash += hash_expr_1 (XVECEXP (x, i, j), 0, do_not_record_p); | |
1548 | if (*do_not_record_p) | |
1549 | return 0; | |
1550 | } | |
1551 | else if (fmt[i] == 's') | |
1552 | { | |
1553 | register unsigned char *p = (unsigned char *) XSTR (x, i); | |
1554 | if (p) | |
1555 | while (*p) | |
1556 | hash += *p++; | |
1557 | } | |
1558 | else if (fmt[i] == 'i') | |
1559 | { | |
1560 | register unsigned tem = XINT (x, i); | |
1561 | hash += tem; | |
1562 | } | |
1563 | else | |
1564 | abort (); | |
1565 | } | |
1566 | ||
1567 | return hash; | |
1568 | } | |
1569 | ||
1570 | /* Hash a set of register REGNO. | |
1571 | ||
1572 | Sets are hashed on the register that is set. | |
1573 | This simplifies the PRE copy propagation code. | |
1574 | ||
1575 | ??? May need to make things more elaborate. Later, as necessary. */ | |
1576 | ||
1577 | static unsigned int | |
1578 | hash_set (regno, hash_table_size) | |
1579 | int regno; | |
1580 | int hash_table_size; | |
1581 | { | |
1582 | unsigned int hash; | |
1583 | ||
1584 | hash = regno; | |
1585 | return hash % hash_table_size; | |
1586 | } | |
1587 | ||
1588 | /* Return non-zero if exp1 is equivalent to exp2. | |
1589 | ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */ | |
1590 | ||
1591 | static int | |
1592 | expr_equiv_p (x, y) | |
1593 | rtx x, y; | |
1594 | { | |
1595 | register int i, j; | |
1596 | register enum rtx_code code; | |
6f7d635c | 1597 | register const char *fmt; |
7506f491 DE |
1598 | |
1599 | if (x == y) | |
1600 | return 1; | |
1601 | if (x == 0 || y == 0) | |
1602 | return x == y; | |
1603 | ||
1604 | code = GET_CODE (x); | |
1605 | if (code != GET_CODE (y)) | |
1606 | return 0; | |
1607 | ||
1608 | /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */ | |
1609 | if (GET_MODE (x) != GET_MODE (y)) | |
1610 | return 0; | |
1611 | ||
1612 | switch (code) | |
1613 | { | |
1614 | case PC: | |
1615 | case CC0: | |
1616 | return x == y; | |
1617 | ||
1618 | case CONST_INT: | |
1619 | return INTVAL (x) == INTVAL (y); | |
1620 | ||
1621 | case LABEL_REF: | |
1622 | return XEXP (x, 0) == XEXP (y, 0); | |
1623 | ||
1624 | case SYMBOL_REF: | |
1625 | return XSTR (x, 0) == XSTR (y, 0); | |
1626 | ||
1627 | case REG: | |
1628 | return REGNO (x) == REGNO (y); | |
1629 | ||
297c3335 RH |
1630 | case MEM: |
1631 | /* Can't merge two expressions in different alias sets, since we can | |
1632 | decide that the expression is transparent in a block when it isn't, | |
1633 | due to it being set with the different alias set. */ | |
1634 | if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y)) | |
1635 | return 0; | |
1636 | break; | |
1637 | ||
7506f491 DE |
1638 | /* For commutative operations, check both orders. */ |
1639 | case PLUS: | |
1640 | case MULT: | |
1641 | case AND: | |
1642 | case IOR: | |
1643 | case XOR: | |
1644 | case NE: | |
1645 | case EQ: | |
1646 | return ((expr_equiv_p (XEXP (x, 0), XEXP (y, 0)) | |
1647 | && expr_equiv_p (XEXP (x, 1), XEXP (y, 1))) | |
1648 | || (expr_equiv_p (XEXP (x, 0), XEXP (y, 1)) | |
1649 | && expr_equiv_p (XEXP (x, 1), XEXP (y, 0)))); | |
1650 | ||
1651 | default: | |
1652 | break; | |
1653 | } | |
1654 | ||
1655 | /* Compare the elements. If any pair of corresponding elements | |
1656 | fail to match, return 0 for the whole thing. */ | |
1657 | ||
1658 | fmt = GET_RTX_FORMAT (code); | |
1659 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
1660 | { | |
1661 | switch (fmt[i]) | |
1662 | { | |
1663 | case 'e': | |
1664 | if (! expr_equiv_p (XEXP (x, i), XEXP (y, i))) | |
1665 | return 0; | |
1666 | break; | |
1667 | ||
1668 | case 'E': | |
1669 | if (XVECLEN (x, i) != XVECLEN (y, i)) | |
1670 | return 0; | |
1671 | for (j = 0; j < XVECLEN (x, i); j++) | |
1672 | if (! expr_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j))) | |
1673 | return 0; | |
1674 | break; | |
1675 | ||
1676 | case 's': | |
1677 | if (strcmp (XSTR (x, i), XSTR (y, i))) | |
1678 | return 0; | |
1679 | break; | |
1680 | ||
1681 | case 'i': | |
1682 | if (XINT (x, i) != XINT (y, i)) | |
1683 | return 0; | |
1684 | break; | |
1685 | ||
1686 | case 'w': | |
1687 | if (XWINT (x, i) != XWINT (y, i)) | |
1688 | return 0; | |
1689 | break; | |
1690 | ||
1691 | case '0': | |
1692 | break; | |
1693 | ||
1694 | default: | |
1695 | abort (); | |
1696 | } | |
1697 | } | |
1698 | ||
1699 | return 1; | |
1700 | } | |
1701 | ||
1702 | /* Insert expression X in INSN in the hash table. | |
1703 | If it is already present, record it as the last occurrence in INSN's | |
1704 | basic block. | |
1705 | ||
1706 | MODE is the mode of the value X is being stored into. | |
1707 | It is only used if X is a CONST_INT. | |
1708 | ||
1709 | ANTIC_P is non-zero if X is an anticipatable expression. | |
1710 | AVAIL_P is non-zero if X is an available expression. */ | |
1711 | ||
1712 | static void | |
1713 | insert_expr_in_table (x, mode, insn, antic_p, avail_p) | |
1714 | rtx x; | |
1715 | enum machine_mode mode; | |
1716 | rtx insn; | |
1717 | int antic_p, avail_p; | |
1718 | { | |
1719 | int found, do_not_record_p; | |
1720 | unsigned int hash; | |
1721 | struct expr *cur_expr, *last_expr = NULL; | |
1722 | struct occr *antic_occr, *avail_occr; | |
1723 | struct occr *last_occr = NULL; | |
1724 | ||
1725 | hash = hash_expr (x, mode, &do_not_record_p, expr_hash_table_size); | |
1726 | ||
1727 | /* Do not insert expression in table if it contains volatile operands, | |
1728 | or if hash_expr determines the expression is something we don't want | |
1729 | to or can't handle. */ | |
1730 | if (do_not_record_p) | |
1731 | return; | |
1732 | ||
1733 | cur_expr = expr_hash_table[hash]; | |
1734 | found = 0; | |
1735 | ||
1736 | while (cur_expr && ! (found = expr_equiv_p (cur_expr->expr, x))) | |
1737 | { | |
1738 | /* If the expression isn't found, save a pointer to the end of | |
1739 | the list. */ | |
1740 | last_expr = cur_expr; | |
1741 | cur_expr = cur_expr->next_same_hash; | |
1742 | } | |
1743 | ||
1744 | if (! found) | |
1745 | { | |
1746 | cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr)); | |
1747 | bytes_used += sizeof (struct expr); | |
1748 | if (expr_hash_table[hash] == NULL) | |
1749 | { | |
1750 | /* This is the first pattern that hashed to this index. */ | |
1751 | expr_hash_table[hash] = cur_expr; | |
1752 | } | |
1753 | else | |
1754 | { | |
1755 | /* Add EXPR to end of this hash chain. */ | |
1756 | last_expr->next_same_hash = cur_expr; | |
1757 | } | |
1758 | /* Set the fields of the expr element. */ | |
1759 | cur_expr->expr = x; | |
1760 | cur_expr->bitmap_index = n_exprs++; | |
1761 | cur_expr->next_same_hash = NULL; | |
1762 | cur_expr->antic_occr = NULL; | |
1763 | cur_expr->avail_occr = NULL; | |
1764 | } | |
1765 | ||
1766 | /* Now record the occurrence(s). */ | |
1767 | ||
1768 | if (antic_p) | |
1769 | { | |
1770 | antic_occr = cur_expr->antic_occr; | |
1771 | ||
1772 | /* Search for another occurrence in the same basic block. */ | |
1773 | while (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn)) | |
1774 | { | |
1775 | /* If an occurrence isn't found, save a pointer to the end of | |
1776 | the list. */ | |
1777 | last_occr = antic_occr; | |
1778 | antic_occr = antic_occr->next; | |
1779 | } | |
1780 | ||
1781 | if (antic_occr) | |
1782 | { | |
1783 | /* Found another instance of the expression in the same basic block. | |
1784 | Prefer the currently recorded one. We want the first one in the | |
1785 | block and the block is scanned from start to end. */ | |
1786 | ; /* nothing to do */ | |
1787 | } | |
1788 | else | |
1789 | { | |
1790 | /* First occurrence of this expression in this basic block. */ | |
1791 | antic_occr = (struct occr *) gcse_alloc (sizeof (struct occr)); | |
1792 | bytes_used += sizeof (struct occr); | |
1793 | /* First occurrence of this expression in any block? */ | |
1794 | if (cur_expr->antic_occr == NULL) | |
1795 | cur_expr->antic_occr = antic_occr; | |
1796 | else | |
1797 | last_occr->next = antic_occr; | |
1798 | antic_occr->insn = insn; | |
1799 | antic_occr->next = NULL; | |
1800 | } | |
1801 | } | |
1802 | ||
1803 | if (avail_p) | |
1804 | { | |
1805 | avail_occr = cur_expr->avail_occr; | |
1806 | ||
1807 | /* Search for another occurrence in the same basic block. */ | |
1808 | while (avail_occr && BLOCK_NUM (avail_occr->insn) != BLOCK_NUM (insn)) | |
1809 | { | |
1810 | /* If an occurrence isn't found, save a pointer to the end of | |
1811 | the list. */ | |
1812 | last_occr = avail_occr; | |
1813 | avail_occr = avail_occr->next; | |
1814 | } | |
1815 | ||
1816 | if (avail_occr) | |
1817 | { | |
1818 | /* Found another instance of the expression in the same basic block. | |
1819 | Prefer this occurrence to the currently recorded one. We want | |
1820 | the last one in the block and the block is scanned from start | |
1821 | to end. */ | |
1822 | avail_occr->insn = insn; | |
1823 | } | |
1824 | else | |
1825 | { | |
1826 | /* First occurrence of this expression in this basic block. */ | |
1827 | avail_occr = (struct occr *) gcse_alloc (sizeof (struct occr)); | |
1828 | bytes_used += sizeof (struct occr); | |
1829 | /* First occurrence of this expression in any block? */ | |
1830 | if (cur_expr->avail_occr == NULL) | |
1831 | cur_expr->avail_occr = avail_occr; | |
1832 | else | |
1833 | last_occr->next = avail_occr; | |
1834 | avail_occr->insn = insn; | |
1835 | avail_occr->next = NULL; | |
1836 | } | |
1837 | } | |
1838 | } | |
1839 | ||
1840 | /* Insert pattern X in INSN in the hash table. | |
1841 | X is a SET of a reg to either another reg or a constant. | |
1842 | If it is already present, record it as the last occurrence in INSN's | |
1843 | basic block. */ | |
1844 | ||
1845 | static void | |
1846 | insert_set_in_table (x, insn) | |
1847 | rtx x; | |
1848 | rtx insn; | |
1849 | { | |
1850 | int found; | |
1851 | unsigned int hash; | |
1852 | struct expr *cur_expr, *last_expr = NULL; | |
1853 | struct occr *cur_occr, *last_occr = NULL; | |
1854 | ||
1855 | if (GET_CODE (x) != SET | |
1856 | || GET_CODE (SET_DEST (x)) != REG) | |
1857 | abort (); | |
1858 | ||
1859 | hash = hash_set (REGNO (SET_DEST (x)), set_hash_table_size); | |
1860 | ||
1861 | cur_expr = set_hash_table[hash]; | |
1862 | found = 0; | |
1863 | ||
1864 | while (cur_expr && ! (found = expr_equiv_p (cur_expr->expr, x))) | |
1865 | { | |
1866 | /* If the expression isn't found, save a pointer to the end of | |
1867 | the list. */ | |
1868 | last_expr = cur_expr; | |
1869 | cur_expr = cur_expr->next_same_hash; | |
1870 | } | |
1871 | ||
1872 | if (! found) | |
1873 | { | |
1874 | cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr)); | |
1875 | bytes_used += sizeof (struct expr); | |
1876 | if (set_hash_table[hash] == NULL) | |
1877 | { | |
1878 | /* This is the first pattern that hashed to this index. */ | |
1879 | set_hash_table[hash] = cur_expr; | |
1880 | } | |
1881 | else | |
1882 | { | |
1883 | /* Add EXPR to end of this hash chain. */ | |
1884 | last_expr->next_same_hash = cur_expr; | |
1885 | } | |
1886 | /* Set the fields of the expr element. | |
1887 | We must copy X because it can be modified when copy propagation is | |
1888 | performed on its operands. */ | |
1889 | /* ??? Should this go in a different obstack? */ | |
1890 | cur_expr->expr = copy_rtx (x); | |
1891 | cur_expr->bitmap_index = n_sets++; | |
1892 | cur_expr->next_same_hash = NULL; | |
1893 | cur_expr->antic_occr = NULL; | |
1894 | cur_expr->avail_occr = NULL; | |
1895 | } | |
1896 | ||
1897 | /* Now record the occurrence. */ | |
1898 | ||
1899 | cur_occr = cur_expr->avail_occr; | |
1900 | ||
1901 | /* Search for another occurrence in the same basic block. */ | |
1902 | while (cur_occr && BLOCK_NUM (cur_occr->insn) != BLOCK_NUM (insn)) | |
1903 | { | |
1904 | /* If an occurrence isn't found, save a pointer to the end of | |
1905 | the list. */ | |
1906 | last_occr = cur_occr; | |
1907 | cur_occr = cur_occr->next; | |
1908 | } | |
1909 | ||
1910 | if (cur_occr) | |
1911 | { | |
1912 | /* Found another instance of the expression in the same basic block. | |
1913 | Prefer this occurrence to the currently recorded one. We want | |
1914 | the last one in the block and the block is scanned from start | |
1915 | to end. */ | |
1916 | cur_occr->insn = insn; | |
1917 | } | |
1918 | else | |
1919 | { | |
1920 | /* First occurrence of this expression in this basic block. */ | |
1921 | cur_occr = (struct occr *) gcse_alloc (sizeof (struct occr)); | |
1922 | bytes_used += sizeof (struct occr); | |
1923 | /* First occurrence of this expression in any block? */ | |
1924 | if (cur_expr->avail_occr == NULL) | |
1925 | cur_expr->avail_occr = cur_occr; | |
1926 | else | |
1927 | last_occr->next = cur_occr; | |
1928 | cur_occr->insn = insn; | |
1929 | cur_occr->next = NULL; | |
1930 | } | |
1931 | } | |
1932 | ||
1933 | /* Scan pattern PAT of INSN and add an entry to the hash table. | |
1934 | If SET_P is non-zero, this is for the assignment hash table, | |
1935 | otherwise it is for the expression hash table. */ | |
1936 | ||
1937 | static void | |
1938 | hash_scan_set (pat, insn, set_p) | |
1939 | rtx pat, insn; | |
1940 | int set_p; | |
1941 | { | |
1942 | rtx src = SET_SRC (pat); | |
1943 | rtx dest = SET_DEST (pat); | |
1944 | ||
1945 | if (GET_CODE (src) == CALL) | |
1946 | hash_scan_call (src, insn); | |
1947 | ||
1948 | if (GET_CODE (dest) == REG) | |
1949 | { | |
1950 | int regno = REGNO (dest); | |
1951 | rtx tmp; | |
1952 | ||
1953 | /* Only record sets of pseudo-regs in the hash table. */ | |
1954 | if (! set_p | |
1955 | && regno >= FIRST_PSEUDO_REGISTER | |
1956 | /* Don't GCSE something if we can't do a reg/reg copy. */ | |
1957 | && can_copy_p [GET_MODE (dest)] | |
1958 | /* Is SET_SRC something we want to gcse? */ | |
1959 | && want_to_gcse_p (src)) | |
1960 | { | |
1961 | /* An expression is not anticipatable if its operands are | |
1962 | modified before this insn. */ | |
3cce638b | 1963 | int antic_p = oprs_anticipatable_p (src, insn); |
7506f491 DE |
1964 | /* An expression is not available if its operands are |
1965 | subsequently modified, including this insn. */ | |
1966 | int avail_p = oprs_available_p (src, insn); | |
1967 | insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p); | |
1968 | } | |
1969 | /* Record sets for constant/copy propagation. */ | |
1970 | else if (set_p | |
1971 | && regno >= FIRST_PSEUDO_REGISTER | |
1972 | && ((GET_CODE (src) == REG | |
1973 | && REGNO (src) >= FIRST_PSEUDO_REGISTER | |
1974 | && can_copy_p [GET_MODE (dest)]) | |
e78d9500 | 1975 | || GET_CODE (src) == CONST_INT |
05f6f07c | 1976 | || GET_CODE (src) == SYMBOL_REF |
e78d9500 | 1977 | || GET_CODE (src) == CONST_DOUBLE) |
7506f491 DE |
1978 | /* A copy is not available if its src or dest is subsequently |
1979 | modified. Here we want to search from INSN+1 on, but | |
1980 | oprs_available_p searches from INSN on. */ | |
1981 | && (insn == BLOCK_END (BLOCK_NUM (insn)) | |
1982 | || ((tmp = next_nonnote_insn (insn)) != NULL_RTX | |
1983 | && oprs_available_p (pat, tmp)))) | |
1984 | insert_set_in_table (pat, insn); | |
1985 | } | |
7506f491 DE |
1986 | } |
1987 | ||
1988 | static void | |
1989 | hash_scan_clobber (x, insn) | |
50b2596f | 1990 | rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED; |
7506f491 DE |
1991 | { |
1992 | /* Currently nothing to do. */ | |
1993 | } | |
1994 | ||
1995 | static void | |
1996 | hash_scan_call (x, insn) | |
50b2596f | 1997 | rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED; |
7506f491 DE |
1998 | { |
1999 | /* Currently nothing to do. */ | |
2000 | } | |
2001 | ||
2002 | /* Process INSN and add hash table entries as appropriate. | |
2003 | ||
2004 | Only available expressions that set a single pseudo-reg are recorded. | |
2005 | ||
2006 | Single sets in a PARALLEL could be handled, but it's an extra complication | |
2007 | that isn't dealt with right now. The trick is handling the CLOBBERs that | |
2008 | are also in the PARALLEL. Later. | |
2009 | ||
2010 | If SET_P is non-zero, this is for the assignment hash table, | |
ed79bb3d R |
2011 | otherwise it is for the expression hash table. |
2012 | If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should | |
2013 | not record any expressions. */ | |
7506f491 DE |
2014 | |
2015 | static void | |
ed79bb3d | 2016 | hash_scan_insn (insn, set_p, in_libcall_block) |
7506f491 DE |
2017 | rtx insn; |
2018 | int set_p; | |
48e87cef | 2019 | int in_libcall_block; |
7506f491 DE |
2020 | { |
2021 | rtx pat = PATTERN (insn); | |
2022 | ||
2023 | /* Pick out the sets of INSN and for other forms of instructions record | |
2024 | what's been modified. */ | |
2025 | ||
ed79bb3d | 2026 | if (GET_CODE (pat) == SET && ! in_libcall_block) |
21e3a717 BS |
2027 | { |
2028 | /* Ignore obvious no-ops. */ | |
2029 | if (SET_SRC (pat) != SET_DEST (pat)) | |
2030 | hash_scan_set (pat, insn, set_p); | |
2031 | } | |
7506f491 DE |
2032 | else if (GET_CODE (pat) == PARALLEL) |
2033 | { | |
2034 | int i; | |
2035 | ||
2036 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
2037 | { | |
2038 | rtx x = XVECEXP (pat, 0, i); | |
2039 | ||
2040 | if (GET_CODE (x) == SET) | |
2041 | { | |
2042 | if (GET_CODE (SET_SRC (x)) == CALL) | |
2043 | hash_scan_call (SET_SRC (x), insn); | |
7506f491 DE |
2044 | } |
2045 | else if (GET_CODE (x) == CLOBBER) | |
2046 | hash_scan_clobber (x, insn); | |
2047 | else if (GET_CODE (x) == CALL) | |
2048 | hash_scan_call (x, insn); | |
2049 | } | |
2050 | } | |
2051 | else if (GET_CODE (pat) == CLOBBER) | |
2052 | hash_scan_clobber (pat, insn); | |
2053 | else if (GET_CODE (pat) == CALL) | |
2054 | hash_scan_call (pat, insn); | |
2055 | } | |
2056 | ||
2057 | static void | |
2058 | dump_hash_table (file, name, table, table_size, total_size) | |
2059 | FILE *file; | |
dff01034 | 2060 | const char *name; |
7506f491 DE |
2061 | struct expr **table; |
2062 | int table_size, total_size; | |
2063 | { | |
2064 | int i; | |
2065 | /* Flattened out table, so it's printed in proper order. */ | |
4da896b2 MM |
2066 | struct expr **flat_table; |
2067 | unsigned int *hash_val; | |
2068 | ||
2069 | flat_table | |
2070 | = (struct expr **) xcalloc (total_size, sizeof (struct expr *)); | |
2071 | hash_val = (unsigned int *) xmalloc (total_size * sizeof (unsigned int)); | |
7506f491 | 2072 | |
7506f491 DE |
2073 | for (i = 0; i < table_size; i++) |
2074 | { | |
2075 | struct expr *expr; | |
2076 | ||
2077 | for (expr = table[i]; expr != NULL; expr = expr->next_same_hash) | |
2078 | { | |
2079 | flat_table[expr->bitmap_index] = expr; | |
2080 | hash_val[expr->bitmap_index] = i; | |
2081 | } | |
2082 | } | |
2083 | ||
2084 | fprintf (file, "%s hash table (%d buckets, %d entries)\n", | |
2085 | name, table_size, total_size); | |
2086 | ||
2087 | for (i = 0; i < total_size; i++) | |
2088 | { | |
2089 | struct expr *expr = flat_table[i]; | |
2090 | ||
2091 | fprintf (file, "Index %d (hash value %d)\n ", | |
2092 | expr->bitmap_index, hash_val[i]); | |
2093 | print_rtl (file, expr->expr); | |
2094 | fprintf (file, "\n"); | |
2095 | } | |
2096 | ||
2097 | fprintf (file, "\n"); | |
4da896b2 MM |
2098 | |
2099 | /* Clean up. */ | |
2100 | free (flat_table); | |
2101 | free (hash_val); | |
7506f491 DE |
2102 | } |
2103 | ||
2104 | /* Record register first/last/block set information for REGNO in INSN. | |
2105 | reg_first_set records the first place in the block where the register | |
2106 | is set and is used to compute "anticipatability". | |
2107 | reg_last_set records the last place in the block where the register | |
2108 | is set and is used to compute "availability". | |
2109 | reg_set_in_block records whether the register is set in the block | |
2110 | and is used to compute "transparency". */ | |
2111 | ||
2112 | static void | |
2113 | record_last_reg_set_info (insn, regno) | |
2114 | rtx insn; | |
2115 | int regno; | |
2116 | { | |
b86ba9c8 | 2117 | if (reg_first_set[regno] == NEVER_SET) |
7506f491 DE |
2118 | reg_first_set[regno] = INSN_CUID (insn); |
2119 | reg_last_set[regno] = INSN_CUID (insn); | |
2120 | SET_BIT (reg_set_in_block[BLOCK_NUM (insn)], regno); | |
2121 | } | |
2122 | ||
2123 | /* Record memory first/last/block set information for INSN. */ | |
2124 | ||
2125 | static void | |
2126 | record_last_mem_set_info (insn) | |
2127 | rtx insn; | |
2128 | { | |
b86ba9c8 | 2129 | if (mem_first_set == NEVER_SET) |
7506f491 DE |
2130 | mem_first_set = INSN_CUID (insn); |
2131 | mem_last_set = INSN_CUID (insn); | |
2132 | mem_set_in_block[BLOCK_NUM (insn)] = 1; | |
2133 | } | |
2134 | ||
7506f491 | 2135 | /* Called from compute_hash_table via note_stores to handle one |
84832317 MM |
2136 | SET or CLOBBER in an insn. DATA is really the instruction in which |
2137 | the SET is taking place. */ | |
7506f491 DE |
2138 | |
2139 | static void | |
84832317 | 2140 | record_last_set_info (dest, setter, data) |
50b2596f | 2141 | rtx dest, setter ATTRIBUTE_UNUSED; |
84832317 | 2142 | void *data; |
7506f491 | 2143 | { |
84832317 MM |
2144 | rtx last_set_insn = (rtx) data; |
2145 | ||
7506f491 DE |
2146 | if (GET_CODE (dest) == SUBREG) |
2147 | dest = SUBREG_REG (dest); | |
2148 | ||
2149 | if (GET_CODE (dest) == REG) | |
2150 | record_last_reg_set_info (last_set_insn, REGNO (dest)); | |
2151 | else if (GET_CODE (dest) == MEM | |
2152 | /* Ignore pushes, they clobber nothing. */ | |
2153 | && ! push_operand (dest, GET_MODE (dest))) | |
2154 | record_last_mem_set_info (last_set_insn); | |
2155 | } | |
2156 | ||
2157 | /* Top level function to create an expression or assignment hash table. | |
2158 | ||
2159 | Expression entries are placed in the hash table if | |
2160 | - they are of the form (set (pseudo-reg) src), | |
2161 | - src is something we want to perform GCSE on, | |
2162 | - none of the operands are subsequently modified in the block | |
2163 | ||
2164 | Assignment entries are placed in the hash table if | |
2165 | - they are of the form (set (pseudo-reg) src), | |
2166 | - src is something we want to perform const/copy propagation on, | |
2167 | - none of the operands or target are subsequently modified in the block | |
2168 | Currently src must be a pseudo-reg or a const_int. | |
2169 | ||
2170 | F is the first insn. | |
2171 | SET_P is non-zero for computing the assignment hash table. */ | |
2172 | ||
2173 | static void | |
b5ce41ff | 2174 | compute_hash_table (set_p) |
7506f491 DE |
2175 | int set_p; |
2176 | { | |
2177 | int bb; | |
2178 | ||
2179 | /* While we compute the hash table we also compute a bit array of which | |
2180 | registers are set in which blocks. | |
2181 | We also compute which blocks set memory, in the absence of aliasing | |
2182 | support [which is TODO]. | |
2183 | ??? This isn't needed during const/copy propagation, but it's cheap to | |
2184 | compute. Later. */ | |
2185 | sbitmap_vector_zero (reg_set_in_block, n_basic_blocks); | |
2186 | bzero ((char *) mem_set_in_block, n_basic_blocks); | |
2187 | ||
2188 | /* Some working arrays used to track first and last set in each block. */ | |
2189 | /* ??? One could use alloca here, but at some size a threshold is crossed | |
2190 | beyond which one should use malloc. Are we at that threshold here? */ | |
2191 | reg_first_set = (int *) gmalloc (max_gcse_regno * sizeof (int)); | |
2192 | reg_last_set = (int *) gmalloc (max_gcse_regno * sizeof (int)); | |
2193 | ||
2194 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2195 | { | |
2196 | rtx insn; | |
2197 | int regno; | |
ed79bb3d | 2198 | int in_libcall_block; |
b86ba9c8 | 2199 | int i; |
7506f491 DE |
2200 | |
2201 | /* First pass over the instructions records information used to | |
2202 | determine when registers and memory are first and last set. | |
2203 | ??? The mem_set_in_block and hard-reg reg_set_in_block computation | |
2204 | could be moved to compute_sets since they currently don't change. */ | |
2205 | ||
b86ba9c8 GK |
2206 | for (i = 0; i < max_gcse_regno; i++) |
2207 | reg_first_set[i] = reg_last_set[i] = NEVER_SET; | |
2208 | mem_first_set = NEVER_SET; | |
2209 | mem_last_set = NEVER_SET; | |
7506f491 | 2210 | |
3b413743 RH |
2211 | for (insn = BLOCK_HEAD (bb); |
2212 | insn && insn != NEXT_INSN (BLOCK_END (bb)); | |
7506f491 DE |
2213 | insn = NEXT_INSN (insn)) |
2214 | { | |
2215 | #ifdef NON_SAVING_SETJMP | |
2216 | if (NON_SAVING_SETJMP && GET_CODE (insn) == NOTE | |
2217 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP) | |
2218 | { | |
2219 | for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) | |
2220 | record_last_reg_set_info (insn, regno); | |
2221 | continue; | |
2222 | } | |
2223 | #endif | |
2224 | ||
2225 | if (GET_RTX_CLASS (GET_CODE (insn)) != 'i') | |
2226 | continue; | |
2227 | ||
2228 | if (GET_CODE (insn) == CALL_INSN) | |
2229 | { | |
2230 | for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) | |
15f8470f JL |
2231 | if ((call_used_regs[regno] |
2232 | && regno != STACK_POINTER_REGNUM | |
2233 | #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2234 | && regno != HARD_FRAME_POINTER_REGNUM | |
2235 | #endif | |
2236 | #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2237 | && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno]) | |
2238 | #endif | |
2239 | #if defined (PIC_OFFSET_TABLE_REGNUM) && !defined (PIC_OFFSET_TABLE_REG_CALL_CLOBBERED) | |
2240 | && ! (regno == PIC_OFFSET_TABLE_REGNUM && flag_pic) | |
2241 | #endif | |
2242 | ||
2243 | && regno != FRAME_POINTER_REGNUM) | |
2244 | || global_regs[regno]) | |
7506f491 DE |
2245 | record_last_reg_set_info (insn, regno); |
2246 | if (! CONST_CALL_P (insn)) | |
2247 | record_last_mem_set_info (insn); | |
2248 | } | |
2249 | ||
84832317 | 2250 | note_stores (PATTERN (insn), record_last_set_info, insn); |
7506f491 DE |
2251 | } |
2252 | ||
2253 | /* The next pass builds the hash table. */ | |
2254 | ||
3b413743 RH |
2255 | for (insn = BLOCK_HEAD (bb), in_libcall_block = 0; |
2256 | insn && insn != NEXT_INSN (BLOCK_END (bb)); | |
7506f491 DE |
2257 | insn = NEXT_INSN (insn)) |
2258 | { | |
2259 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
ed79bb3d R |
2260 | { |
2261 | if (find_reg_note (insn, REG_LIBCALL, NULL_RTX)) | |
2262 | in_libcall_block = 1; | |
2263 | else if (find_reg_note (insn, REG_RETVAL, NULL_RTX)) | |
2264 | in_libcall_block = 0; | |
2265 | hash_scan_insn (insn, set_p, in_libcall_block); | |
2266 | } | |
7506f491 DE |
2267 | } |
2268 | } | |
2269 | ||
2270 | free (reg_first_set); | |
2271 | free (reg_last_set); | |
2272 | /* Catch bugs early. */ | |
2273 | reg_first_set = reg_last_set = 0; | |
2274 | } | |
2275 | ||
2276 | /* Allocate space for the set hash table. | |
2277 | N_INSNS is the number of instructions in the function. | |
2278 | It is used to determine the number of buckets to use. */ | |
2279 | ||
2280 | static void | |
2281 | alloc_set_hash_table (n_insns) | |
2282 | int n_insns; | |
2283 | { | |
2284 | int n; | |
2285 | ||
2286 | set_hash_table_size = n_insns / 4; | |
2287 | if (set_hash_table_size < 11) | |
2288 | set_hash_table_size = 11; | |
2289 | /* Attempt to maintain efficient use of hash table. | |
2290 | Making it an odd number is simplest for now. | |
2291 | ??? Later take some measurements. */ | |
2292 | set_hash_table_size |= 1; | |
2293 | n = set_hash_table_size * sizeof (struct expr *); | |
2294 | set_hash_table = (struct expr **) gmalloc (n); | |
2295 | } | |
2296 | ||
2297 | /* Free things allocated by alloc_set_hash_table. */ | |
2298 | ||
2299 | static void | |
2300 | free_set_hash_table () | |
2301 | { | |
2302 | free (set_hash_table); | |
2303 | } | |
2304 | ||
2305 | /* Compute the hash table for doing copy/const propagation. */ | |
2306 | ||
2307 | static void | |
b5ce41ff | 2308 | compute_set_hash_table () |
7506f491 DE |
2309 | { |
2310 | /* Initialize count of number of entries in hash table. */ | |
2311 | n_sets = 0; | |
2312 | bzero ((char *) set_hash_table, set_hash_table_size * sizeof (struct expr *)); | |
2313 | ||
b5ce41ff | 2314 | compute_hash_table (1); |
7506f491 DE |
2315 | } |
2316 | ||
2317 | /* Allocate space for the expression hash table. | |
2318 | N_INSNS is the number of instructions in the function. | |
2319 | It is used to determine the number of buckets to use. */ | |
2320 | ||
2321 | static void | |
2322 | alloc_expr_hash_table (n_insns) | |
2323 | int n_insns; | |
2324 | { | |
2325 | int n; | |
2326 | ||
2327 | expr_hash_table_size = n_insns / 2; | |
2328 | /* Make sure the amount is usable. */ | |
2329 | if (expr_hash_table_size < 11) | |
2330 | expr_hash_table_size = 11; | |
2331 | /* Attempt to maintain efficient use of hash table. | |
2332 | Making it an odd number is simplest for now. | |
2333 | ??? Later take some measurements. */ | |
2334 | expr_hash_table_size |= 1; | |
2335 | n = expr_hash_table_size * sizeof (struct expr *); | |
2336 | expr_hash_table = (struct expr **) gmalloc (n); | |
2337 | } | |
2338 | ||
2339 | /* Free things allocated by alloc_expr_hash_table. */ | |
2340 | ||
2341 | static void | |
2342 | free_expr_hash_table () | |
2343 | { | |
2344 | free (expr_hash_table); | |
2345 | } | |
2346 | ||
2347 | /* Compute the hash table for doing GCSE. */ | |
2348 | ||
2349 | static void | |
b5ce41ff | 2350 | compute_expr_hash_table () |
7506f491 DE |
2351 | { |
2352 | /* Initialize count of number of entries in hash table. */ | |
2353 | n_exprs = 0; | |
2354 | bzero ((char *) expr_hash_table, expr_hash_table_size * sizeof (struct expr *)); | |
2355 | ||
b5ce41ff | 2356 | compute_hash_table (0); |
7506f491 DE |
2357 | } |
2358 | \f | |
2359 | /* Expression tracking support. */ | |
2360 | ||
2361 | /* Lookup pattern PAT in the expression table. | |
2362 | The result is a pointer to the table entry, or NULL if not found. */ | |
2363 | ||
2364 | static struct expr * | |
2365 | lookup_expr (pat) | |
2366 | rtx pat; | |
2367 | { | |
2368 | int do_not_record_p; | |
2369 | unsigned int hash = hash_expr (pat, GET_MODE (pat), &do_not_record_p, | |
2370 | expr_hash_table_size); | |
2371 | struct expr *expr; | |
2372 | ||
2373 | if (do_not_record_p) | |
2374 | return NULL; | |
2375 | ||
2376 | expr = expr_hash_table[hash]; | |
2377 | ||
2378 | while (expr && ! expr_equiv_p (expr->expr, pat)) | |
2379 | expr = expr->next_same_hash; | |
2380 | ||
2381 | return expr; | |
2382 | } | |
2383 | ||
2384 | /* Lookup REGNO in the set table. | |
2385 | If PAT is non-NULL look for the entry that matches it, otherwise return | |
2386 | the first entry for REGNO. | |
2387 | The result is a pointer to the table entry, or NULL if not found. */ | |
2388 | ||
2389 | static struct expr * | |
2390 | lookup_set (regno, pat) | |
2391 | int regno; | |
2392 | rtx pat; | |
2393 | { | |
2394 | unsigned int hash = hash_set (regno, set_hash_table_size); | |
2395 | struct expr *expr; | |
2396 | ||
2397 | expr = set_hash_table[hash]; | |
2398 | ||
2399 | if (pat) | |
2400 | { | |
2401 | while (expr && ! expr_equiv_p (expr->expr, pat)) | |
2402 | expr = expr->next_same_hash; | |
2403 | } | |
2404 | else | |
2405 | { | |
2406 | while (expr && REGNO (SET_DEST (expr->expr)) != regno) | |
2407 | expr = expr->next_same_hash; | |
2408 | } | |
2409 | ||
2410 | return expr; | |
2411 | } | |
2412 | ||
2413 | /* Return the next entry for REGNO in list EXPR. */ | |
2414 | ||
2415 | static struct expr * | |
2416 | next_set (regno, expr) | |
2417 | int regno; | |
2418 | struct expr *expr; | |
2419 | { | |
2420 | do | |
2421 | expr = expr->next_same_hash; | |
2422 | while (expr && REGNO (SET_DEST (expr->expr)) != regno); | |
2423 | return expr; | |
2424 | } | |
2425 | ||
2426 | /* Reset tables used to keep track of what's still available [since the | |
2427 | start of the block]. */ | |
2428 | ||
2429 | static void | |
2430 | reset_opr_set_tables () | |
2431 | { | |
2432 | /* Maintain a bitmap of which regs have been set since beginning of | |
2433 | the block. */ | |
2434 | sbitmap_zero (reg_set_bitmap); | |
2435 | /* Also keep a record of the last instruction to modify memory. | |
2436 | For now this is very trivial, we only record whether any memory | |
2437 | location has been modified. */ | |
2438 | mem_last_set = 0; | |
2439 | } | |
2440 | ||
2441 | /* Return non-zero if the operands of X are not set before INSN in | |
2442 | INSN's basic block. */ | |
2443 | ||
2444 | static int | |
2445 | oprs_not_set_p (x, insn) | |
2446 | rtx x, insn; | |
2447 | { | |
2448 | int i; | |
2449 | enum rtx_code code; | |
6f7d635c | 2450 | const char *fmt; |
7506f491 DE |
2451 | |
2452 | /* repeat is used to turn tail-recursion into iteration. */ | |
2453 | repeat: | |
2454 | ||
2455 | if (x == 0) | |
2456 | return 1; | |
2457 | ||
2458 | code = GET_CODE (x); | |
2459 | switch (code) | |
2460 | { | |
2461 | case PC: | |
2462 | case CC0: | |
2463 | case CONST: | |
2464 | case CONST_INT: | |
2465 | case CONST_DOUBLE: | |
2466 | case SYMBOL_REF: | |
2467 | case LABEL_REF: | |
2468 | case ADDR_VEC: | |
2469 | case ADDR_DIFF_VEC: | |
2470 | return 1; | |
2471 | ||
2472 | case MEM: | |
2473 | if (mem_last_set != 0) | |
2474 | return 0; | |
2475 | x = XEXP (x, 0); | |
2476 | goto repeat; | |
2477 | ||
2478 | case REG: | |
2479 | return ! TEST_BIT (reg_set_bitmap, REGNO (x)); | |
2480 | ||
2481 | default: | |
2482 | break; | |
2483 | } | |
2484 | ||
2485 | fmt = GET_RTX_FORMAT (code); | |
2486 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2487 | { | |
2488 | if (fmt[i] == 'e') | |
2489 | { | |
2490 | int not_set_p; | |
2491 | /* If we are about to do the last recursive call | |
2492 | needed at this level, change it into iteration. | |
2493 | This function is called enough to be worth it. */ | |
2494 | if (i == 0) | |
2495 | { | |
2496 | x = XEXP (x, 0); | |
2497 | goto repeat; | |
2498 | } | |
2499 | not_set_p = oprs_not_set_p (XEXP (x, i), insn); | |
2500 | if (! not_set_p) | |
2501 | return 0; | |
2502 | } | |
2503 | else if (fmt[i] == 'E') | |
2504 | { | |
2505 | int j; | |
2506 | for (j = 0; j < XVECLEN (x, i); j++) | |
2507 | { | |
2508 | int not_set_p = oprs_not_set_p (XVECEXP (x, i, j), insn); | |
2509 | if (! not_set_p) | |
2510 | return 0; | |
2511 | } | |
2512 | } | |
2513 | } | |
2514 | ||
2515 | return 1; | |
2516 | } | |
2517 | ||
2518 | /* Mark things set by a CALL. */ | |
2519 | ||
2520 | static void | |
b5ce41ff JL |
2521 | mark_call (insn) |
2522 | rtx insn; | |
7506f491 DE |
2523 | { |
2524 | mem_last_set = INSN_CUID (insn); | |
2525 | } | |
2526 | ||
2527 | /* Mark things set by a SET. */ | |
2528 | ||
2529 | static void | |
2530 | mark_set (pat, insn) | |
2531 | rtx pat, insn; | |
2532 | { | |
2533 | rtx dest = SET_DEST (pat); | |
2534 | ||
2535 | while (GET_CODE (dest) == SUBREG | |
2536 | || GET_CODE (dest) == ZERO_EXTRACT | |
2537 | || GET_CODE (dest) == SIGN_EXTRACT | |
2538 | || GET_CODE (dest) == STRICT_LOW_PART) | |
2539 | dest = XEXP (dest, 0); | |
2540 | ||
2541 | if (GET_CODE (dest) == REG) | |
2542 | SET_BIT (reg_set_bitmap, REGNO (dest)); | |
2543 | else if (GET_CODE (dest) == MEM) | |
2544 | mem_last_set = INSN_CUID (insn); | |
2545 | ||
2546 | if (GET_CODE (SET_SRC (pat)) == CALL) | |
b5ce41ff | 2547 | mark_call (insn); |
7506f491 DE |
2548 | } |
2549 | ||
2550 | /* Record things set by a CLOBBER. */ | |
2551 | ||
2552 | static void | |
2553 | mark_clobber (pat, insn) | |
2554 | rtx pat, insn; | |
2555 | { | |
2556 | rtx clob = XEXP (pat, 0); | |
2557 | ||
2558 | while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART) | |
2559 | clob = XEXP (clob, 0); | |
2560 | ||
2561 | if (GET_CODE (clob) == REG) | |
2562 | SET_BIT (reg_set_bitmap, REGNO (clob)); | |
2563 | else | |
2564 | mem_last_set = INSN_CUID (insn); | |
2565 | } | |
2566 | ||
2567 | /* Record things set by INSN. | |
2568 | This data is used by oprs_not_set_p. */ | |
2569 | ||
2570 | static void | |
2571 | mark_oprs_set (insn) | |
2572 | rtx insn; | |
2573 | { | |
2574 | rtx pat = PATTERN (insn); | |
2575 | ||
2576 | if (GET_CODE (pat) == SET) | |
2577 | mark_set (pat, insn); | |
2578 | else if (GET_CODE (pat) == PARALLEL) | |
2579 | { | |
2580 | int i; | |
2581 | ||
2582 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
2583 | { | |
2584 | rtx x = XVECEXP (pat, 0, i); | |
2585 | ||
2586 | if (GET_CODE (x) == SET) | |
2587 | mark_set (x, insn); | |
2588 | else if (GET_CODE (x) == CLOBBER) | |
2589 | mark_clobber (x, insn); | |
2590 | else if (GET_CODE (x) == CALL) | |
b5ce41ff | 2591 | mark_call (insn); |
7506f491 DE |
2592 | } |
2593 | } | |
2594 | else if (GET_CODE (pat) == CLOBBER) | |
2595 | mark_clobber (pat, insn); | |
2596 | else if (GET_CODE (pat) == CALL) | |
b5ce41ff | 2597 | mark_call (insn); |
7506f491 | 2598 | } |
b5ce41ff | 2599 | |
7506f491 DE |
2600 | \f |
2601 | /* Classic GCSE reaching definition support. */ | |
2602 | ||
2603 | /* Allocate reaching def variables. */ | |
2604 | ||
2605 | static void | |
2606 | alloc_rd_mem (n_blocks, n_insns) | |
2607 | int n_blocks, n_insns; | |
2608 | { | |
2609 | rd_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2610 | sbitmap_vector_zero (rd_kill, n_basic_blocks); | |
2611 | ||
2612 | rd_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2613 | sbitmap_vector_zero (rd_gen, n_basic_blocks); | |
2614 | ||
2615 | reaching_defs = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2616 | sbitmap_vector_zero (reaching_defs, n_basic_blocks); | |
2617 | ||
2618 | rd_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2619 | sbitmap_vector_zero (rd_out, n_basic_blocks); | |
2620 | } | |
2621 | ||
2622 | /* Free reaching def variables. */ | |
2623 | ||
2624 | static void | |
2625 | free_rd_mem () | |
2626 | { | |
2627 | free (rd_kill); | |
2628 | free (rd_gen); | |
2629 | free (reaching_defs); | |
2630 | free (rd_out); | |
2631 | } | |
2632 | ||
2633 | /* Add INSN to the kills of BB. | |
2634 | REGNO, set in BB, is killed by INSN. */ | |
2635 | ||
2636 | static void | |
2637 | handle_rd_kill_set (insn, regno, bb) | |
2638 | rtx insn; | |
2639 | int regno, bb; | |
2640 | { | |
2641 | struct reg_set *this_reg = reg_set_table[regno]; | |
2642 | ||
2643 | while (this_reg) | |
2644 | { | |
2645 | if (BLOCK_NUM (this_reg->insn) != BLOCK_NUM (insn)) | |
2646 | SET_BIT (rd_kill[bb], INSN_CUID (this_reg->insn)); | |
2647 | this_reg = this_reg->next; | |
2648 | } | |
2649 | } | |
2650 | ||
7506f491 DE |
2651 | /* Compute the set of kill's for reaching definitions. */ |
2652 | ||
2653 | static void | |
2654 | compute_kill_rd () | |
2655 | { | |
2656 | int bb,cuid; | |
2657 | ||
2658 | /* For each block | |
2659 | For each set bit in `gen' of the block (i.e each insn which | |
ac7c5af5 JL |
2660 | generates a definition in the block) |
2661 | Call the reg set by the insn corresponding to that bit regx | |
2662 | Look at the linked list starting at reg_set_table[regx] | |
2663 | For each setting of regx in the linked list, which is not in | |
2664 | this block | |
2665 | Set the bit in `kill' corresponding to that insn | |
7506f491 DE |
2666 | */ |
2667 | ||
2668 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2669 | { | |
2670 | for (cuid = 0; cuid < max_cuid; cuid++) | |
2671 | { | |
2672 | if (TEST_BIT (rd_gen[bb], cuid)) | |
ac7c5af5 | 2673 | { |
7506f491 DE |
2674 | rtx insn = CUID_INSN (cuid); |
2675 | rtx pat = PATTERN (insn); | |
2676 | ||
2677 | if (GET_CODE (insn) == CALL_INSN) | |
ac7c5af5 | 2678 | { |
7506f491 DE |
2679 | int regno; |
2680 | ||
2681 | for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) | |
ac7c5af5 | 2682 | { |
15f8470f JL |
2683 | if ((call_used_regs[regno] |
2684 | && regno != STACK_POINTER_REGNUM | |
2685 | #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2686 | && regno != HARD_FRAME_POINTER_REGNUM | |
2687 | #endif | |
2688 | #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2689 | && ! (regno == ARG_POINTER_REGNUM | |
2690 | && fixed_regs[regno]) | |
2691 | #endif | |
2692 | #if defined (PIC_OFFSET_TABLE_REGNUM) && !defined (PIC_OFFSET_TABLE_REG_CALL_CLOBBERED) | |
2693 | && ! (regno == PIC_OFFSET_TABLE_REGNUM && flag_pic) | |
2694 | #endif | |
2695 | && regno != FRAME_POINTER_REGNUM) | |
2696 | || global_regs[regno]) | |
7506f491 | 2697 | handle_rd_kill_set (insn, regno, bb); |
ac7c5af5 JL |
2698 | } |
2699 | } | |
7506f491 DE |
2700 | |
2701 | if (GET_CODE (pat) == PARALLEL) | |
2702 | { | |
2703 | int i; | |
2704 | ||
2705 | /* We work backwards because ... */ | |
2706 | for (i = XVECLEN (pat, 0) - 1; i >= 0; i--) | |
2707 | { | |
2708 | enum rtx_code code = GET_CODE (XVECEXP (pat, 0, i)); | |
2709 | if ((code == SET || code == CLOBBER) | |
2710 | && GET_CODE (XEXP (XVECEXP (pat, 0, i), 0)) == REG) | |
2711 | handle_rd_kill_set (insn, | |
2712 | REGNO (XEXP (XVECEXP (pat, 0, i), 0)), | |
2713 | bb); | |
2714 | } | |
2715 | } | |
2716 | else if (GET_CODE (pat) == SET) | |
2717 | { | |
2718 | if (GET_CODE (SET_DEST (pat)) == REG) | |
2719 | { | |
2720 | /* Each setting of this register outside of this block | |
2721 | must be marked in the set of kills in this block. */ | |
2722 | handle_rd_kill_set (insn, REGNO (SET_DEST (pat)), bb); | |
2723 | } | |
ac7c5af5 | 2724 | } |
7506f491 | 2725 | /* FIXME: CLOBBER? */ |
ac7c5af5 | 2726 | } |
7506f491 DE |
2727 | } |
2728 | } | |
2729 | } | |
2730 | ||
2731 | /* Compute the reaching definitions as in | |
2732 | Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman, | |
2733 | Chapter 10. It is the same algorithm as used for computing available | |
2734 | expressions but applied to the gens and kills of reaching definitions. */ | |
2735 | ||
2736 | static void | |
2737 | compute_rd () | |
2738 | { | |
2739 | int bb, changed, passes; | |
2740 | ||
2741 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2742 | sbitmap_copy (rd_out[bb] /*dst*/, rd_gen[bb] /*src*/); | |
2743 | ||
2744 | passes = 0; | |
2745 | changed = 1; | |
2746 | while (changed) | |
2747 | { | |
2748 | changed = 0; | |
2749 | for (bb = 0; bb < n_basic_blocks; bb++) | |
ac7c5af5 | 2750 | { |
36349f8b | 2751 | sbitmap_union_of_preds (reaching_defs[bb], rd_out, bb); |
7506f491 DE |
2752 | changed |= sbitmap_union_of_diff (rd_out[bb], rd_gen[bb], |
2753 | reaching_defs[bb], rd_kill[bb]); | |
ac7c5af5 | 2754 | } |
7506f491 DE |
2755 | passes++; |
2756 | } | |
2757 | ||
2758 | if (gcse_file) | |
2759 | fprintf (gcse_file, "reaching def computation: %d passes\n", passes); | |
2760 | } | |
2761 | \f | |
2762 | /* Classic GCSE available expression support. */ | |
2763 | ||
2764 | /* Allocate memory for available expression computation. */ | |
2765 | ||
2766 | static void | |
2767 | alloc_avail_expr_mem (n_blocks, n_exprs) | |
2768 | int n_blocks, n_exprs; | |
2769 | { | |
2770 | ae_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
2771 | sbitmap_vector_zero (ae_kill, n_basic_blocks); | |
2772 | ||
2773 | ae_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
2774 | sbitmap_vector_zero (ae_gen, n_basic_blocks); | |
2775 | ||
2776 | ae_in = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
2777 | sbitmap_vector_zero (ae_in, n_basic_blocks); | |
2778 | ||
2779 | ae_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
2780 | sbitmap_vector_zero (ae_out, n_basic_blocks); | |
2781 | ||
2782 | u_bitmap = (sbitmap) sbitmap_alloc (n_exprs); | |
2783 | sbitmap_ones (u_bitmap); | |
2784 | } | |
2785 | ||
2786 | static void | |
2787 | free_avail_expr_mem () | |
2788 | { | |
2789 | free (ae_kill); | |
2790 | free (ae_gen); | |
2791 | free (ae_in); | |
2792 | free (ae_out); | |
2793 | free (u_bitmap); | |
2794 | } | |
2795 | ||
2796 | /* Compute the set of available expressions generated in each basic block. */ | |
2797 | ||
2798 | static void | |
2799 | compute_ae_gen () | |
2800 | { | |
2801 | int i; | |
2802 | ||
2803 | /* For each recorded occurrence of each expression, set ae_gen[bb][expr]. | |
2804 | This is all we have to do because an expression is not recorded if it | |
2805 | is not available, and the only expressions we want to work with are the | |
2806 | ones that are recorded. */ | |
2807 | ||
2808 | for (i = 0; i < expr_hash_table_size; i++) | |
2809 | { | |
2810 | struct expr *expr = expr_hash_table[i]; | |
2811 | while (expr != NULL) | |
2812 | { | |
2813 | struct occr *occr = expr->avail_occr; | |
2814 | while (occr != NULL) | |
2815 | { | |
2816 | SET_BIT (ae_gen[BLOCK_NUM (occr->insn)], expr->bitmap_index); | |
2817 | occr = occr->next; | |
2818 | } | |
2819 | expr = expr->next_same_hash; | |
2820 | } | |
2821 | } | |
2822 | } | |
2823 | ||
2824 | /* Return non-zero if expression X is killed in BB. */ | |
2825 | ||
2826 | static int | |
2827 | expr_killed_p (x, bb) | |
2828 | rtx x; | |
2829 | int bb; | |
2830 | { | |
2831 | int i; | |
2832 | enum rtx_code code; | |
6f7d635c | 2833 | const char *fmt; |
7506f491 DE |
2834 | |
2835 | /* repeat is used to turn tail-recursion into iteration. */ | |
2836 | repeat: | |
2837 | ||
2838 | if (x == 0) | |
2839 | return 1; | |
2840 | ||
2841 | code = GET_CODE (x); | |
2842 | switch (code) | |
2843 | { | |
2844 | case REG: | |
2845 | return TEST_BIT (reg_set_in_block[bb], REGNO (x)); | |
2846 | ||
2847 | case MEM: | |
2848 | if (mem_set_in_block[bb]) | |
2849 | return 1; | |
2850 | x = XEXP (x, 0); | |
2851 | goto repeat; | |
2852 | ||
2853 | case PC: | |
2854 | case CC0: /*FIXME*/ | |
2855 | case CONST: | |
2856 | case CONST_INT: | |
2857 | case CONST_DOUBLE: | |
2858 | case SYMBOL_REF: | |
2859 | case LABEL_REF: | |
2860 | case ADDR_VEC: | |
2861 | case ADDR_DIFF_VEC: | |
2862 | return 0; | |
2863 | ||
2864 | default: | |
2865 | break; | |
2866 | } | |
2867 | ||
2868 | i = GET_RTX_LENGTH (code) - 1; | |
2869 | fmt = GET_RTX_FORMAT (code); | |
2870 | for (; i >= 0; i--) | |
2871 | { | |
2872 | if (fmt[i] == 'e') | |
2873 | { | |
2874 | rtx tem = XEXP (x, i); | |
2875 | ||
2876 | /* If we are about to do the last recursive call | |
2877 | needed at this level, change it into iteration. | |
2878 | This function is called enough to be worth it. */ | |
2879 | if (i == 0) | |
2880 | { | |
2881 | x = tem; | |
2882 | goto repeat; | |
2883 | } | |
2884 | if (expr_killed_p (tem, bb)) | |
2885 | return 1; | |
2886 | } | |
2887 | else if (fmt[i] == 'E') | |
2888 | { | |
2889 | int j; | |
2890 | for (j = 0; j < XVECLEN (x, i); j++) | |
2891 | { | |
2892 | if (expr_killed_p (XVECEXP (x, i, j), bb)) | |
2893 | return 1; | |
2894 | } | |
2895 | } | |
2896 | } | |
2897 | ||
2898 | return 0; | |
2899 | } | |
2900 | ||
2901 | /* Compute the set of available expressions killed in each basic block. */ | |
2902 | ||
2903 | static void | |
a42cd965 AM |
2904 | compute_ae_kill (ae_gen, ae_kill) |
2905 | sbitmap *ae_gen, *ae_kill; | |
7506f491 DE |
2906 | { |
2907 | int bb,i; | |
2908 | ||
2909 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2910 | { | |
2911 | for (i = 0; i < expr_hash_table_size; i++) | |
2912 | { | |
2913 | struct expr *expr = expr_hash_table[i]; | |
2914 | ||
2915 | for ( ; expr != NULL; expr = expr->next_same_hash) | |
2916 | { | |
2917 | /* Skip EXPR if generated in this block. */ | |
2918 | if (TEST_BIT (ae_gen[bb], expr->bitmap_index)) | |
2919 | continue; | |
2920 | ||
2921 | if (expr_killed_p (expr->expr, bb)) | |
2922 | SET_BIT (ae_kill[bb], expr->bitmap_index); | |
2923 | } | |
2924 | } | |
2925 | } | |
2926 | } | |
7506f491 DE |
2927 | \f |
2928 | /* Actually perform the Classic GCSE optimizations. */ | |
2929 | ||
2930 | /* Return non-zero if occurrence OCCR of expression EXPR reaches block BB. | |
2931 | ||
2932 | CHECK_SELF_LOOP is non-zero if we should consider a block reaching itself | |
2933 | as a positive reach. We want to do this when there are two computations | |
2934 | of the expression in the block. | |
2935 | ||
2936 | VISITED is a pointer to a working buffer for tracking which BB's have | |
2937 | been visited. It is NULL for the top-level call. | |
2938 | ||
2939 | We treat reaching expressions that go through blocks containing the same | |
2940 | reaching expression as "not reaching". E.g. if EXPR is generated in blocks | |
2941 | 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block | |
2942 | 2 as not reaching. The intent is to improve the probability of finding | |
2943 | only one reaching expression and to reduce register lifetimes by picking | |
2944 | the closest such expression. */ | |
2945 | ||
2946 | static int | |
283a2545 | 2947 | expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited) |
7506f491 DE |
2948 | struct occr *occr; |
2949 | struct expr *expr; | |
2950 | int bb; | |
2951 | int check_self_loop; | |
2952 | char *visited; | |
2953 | { | |
36349f8b | 2954 | edge pred; |
7506f491 | 2955 | |
36349f8b | 2956 | for (pred = BASIC_BLOCK(bb)->pred; pred != NULL; pred = pred->pred_next) |
7506f491 | 2957 | { |
36349f8b | 2958 | int pred_bb = pred->src->index; |
7506f491 DE |
2959 | |
2960 | if (visited[pred_bb]) | |
ac7c5af5 | 2961 | { |
7506f491 DE |
2962 | /* This predecessor has already been visited. |
2963 | Nothing to do. */ | |
2964 | ; | |
2965 | } | |
2966 | else if (pred_bb == bb) | |
ac7c5af5 | 2967 | { |
7506f491 DE |
2968 | /* BB loops on itself. */ |
2969 | if (check_self_loop | |
2970 | && TEST_BIT (ae_gen[pred_bb], expr->bitmap_index) | |
2971 | && BLOCK_NUM (occr->insn) == pred_bb) | |
2972 | return 1; | |
2973 | visited[pred_bb] = 1; | |
ac7c5af5 | 2974 | } |
7506f491 DE |
2975 | /* Ignore this predecessor if it kills the expression. */ |
2976 | else if (TEST_BIT (ae_kill[pred_bb], expr->bitmap_index)) | |
2977 | visited[pred_bb] = 1; | |
2978 | /* Does this predecessor generate this expression? */ | |
2979 | else if (TEST_BIT (ae_gen[pred_bb], expr->bitmap_index)) | |
2980 | { | |
2981 | /* Is this the occurrence we're looking for? | |
2982 | Note that there's only one generating occurrence per block | |
2983 | so we just need to check the block number. */ | |
2984 | if (BLOCK_NUM (occr->insn) == pred_bb) | |
2985 | return 1; | |
2986 | visited[pred_bb] = 1; | |
2987 | } | |
2988 | /* Neither gen nor kill. */ | |
2989 | else | |
ac7c5af5 | 2990 | { |
7506f491 | 2991 | visited[pred_bb] = 1; |
283a2545 RL |
2992 | if (expr_reaches_here_p_work (occr, expr, pred_bb, check_self_loop, |
2993 | visited)) | |
7506f491 | 2994 | return 1; |
ac7c5af5 | 2995 | } |
7506f491 DE |
2996 | } |
2997 | ||
2998 | /* All paths have been checked. */ | |
2999 | return 0; | |
3000 | } | |
3001 | ||
283a2545 RL |
3002 | /* This wrapper for expr_reaches_here_p_work() is to ensure that any |
3003 | memory allocated for that function is returned. */ | |
3004 | ||
3005 | static int | |
3006 | expr_reaches_here_p (occr, expr, bb, check_self_loop) | |
3007 | struct occr *occr; | |
3008 | struct expr *expr; | |
3009 | int bb; | |
3010 | int check_self_loop; | |
3011 | { | |
3012 | int rval; | |
3013 | char * visited = (char *) xcalloc (n_basic_blocks, 1); | |
3014 | ||
3015 | rval = expr_reaches_here_p_work(occr, expr, bb, check_self_loop, visited); | |
3016 | ||
3017 | free (visited); | |
3018 | ||
3019 | return (rval); | |
3020 | } | |
3021 | ||
7506f491 DE |
3022 | /* Return the instruction that computes EXPR that reaches INSN's basic block. |
3023 | If there is more than one such instruction, return NULL. | |
3024 | ||
3025 | Called only by handle_avail_expr. */ | |
3026 | ||
3027 | static rtx | |
3028 | computing_insn (expr, insn) | |
3029 | struct expr *expr; | |
3030 | rtx insn; | |
3031 | { | |
3032 | int bb = BLOCK_NUM (insn); | |
3033 | ||
3034 | if (expr->avail_occr->next == NULL) | |
3035 | { | |
3036 | if (BLOCK_NUM (expr->avail_occr->insn) == bb) | |
3037 | { | |
3038 | /* The available expression is actually itself | |
3039 | (i.e. a loop in the flow graph) so do nothing. */ | |
3040 | return NULL; | |
3041 | } | |
3042 | /* (FIXME) Case that we found a pattern that was created by | |
3043 | a substitution that took place. */ | |
3044 | return expr->avail_occr->insn; | |
3045 | } | |
3046 | else | |
3047 | { | |
3048 | /* Pattern is computed more than once. | |
3049 | Search backwards from this insn to see how many of these | |
3050 | computations actually reach this insn. */ | |
3051 | struct occr *occr; | |
3052 | rtx insn_computes_expr = NULL; | |
3053 | int can_reach = 0; | |
3054 | ||
3055 | for (occr = expr->avail_occr; occr != NULL; occr = occr->next) | |
3056 | { | |
3057 | if (BLOCK_NUM (occr->insn) == bb) | |
3058 | { | |
3059 | /* The expression is generated in this block. | |
3060 | The only time we care about this is when the expression | |
3061 | is generated later in the block [and thus there's a loop]. | |
3062 | We let the normal cse pass handle the other cases. */ | |
3063 | if (INSN_CUID (insn) < INSN_CUID (occr->insn)) | |
3064 | { | |
283a2545 | 3065 | if (expr_reaches_here_p (occr, expr, bb, 1)) |
7506f491 DE |
3066 | { |
3067 | can_reach++; | |
3068 | if (can_reach > 1) | |
3069 | return NULL; | |
3070 | insn_computes_expr = occr->insn; | |
3071 | } | |
3072 | } | |
3073 | } | |
3074 | else /* Computation of the pattern outside this block. */ | |
3075 | { | |
283a2545 | 3076 | if (expr_reaches_here_p (occr, expr, bb, 0)) |
7506f491 DE |
3077 | { |
3078 | can_reach++; | |
3079 | if (can_reach > 1) | |
3080 | return NULL; | |
3081 | insn_computes_expr = occr->insn; | |
3082 | } | |
3083 | } | |
3084 | } | |
3085 | ||
3086 | if (insn_computes_expr == NULL) | |
3087 | abort (); | |
3088 | return insn_computes_expr; | |
3089 | } | |
3090 | } | |
3091 | ||
3092 | /* Return non-zero if the definition in DEF_INSN can reach INSN. | |
3093 | Only called by can_disregard_other_sets. */ | |
3094 | ||
3095 | static int | |
3096 | def_reaches_here_p (insn, def_insn) | |
3097 | rtx insn, def_insn; | |
3098 | { | |
3099 | rtx reg; | |
3100 | ||
3101 | if (TEST_BIT (reaching_defs[BLOCK_NUM (insn)], INSN_CUID (def_insn))) | |
3102 | return 1; | |
3103 | ||
3104 | if (BLOCK_NUM (insn) == BLOCK_NUM (def_insn)) | |
3105 | { | |
3106 | if (INSN_CUID (def_insn) < INSN_CUID (insn)) | |
ac7c5af5 | 3107 | { |
7506f491 DE |
3108 | if (GET_CODE (PATTERN (def_insn)) == PARALLEL) |
3109 | return 1; | |
3110 | if (GET_CODE (PATTERN (def_insn)) == CLOBBER) | |
3111 | reg = XEXP (PATTERN (def_insn), 0); | |
3112 | else if (GET_CODE (PATTERN (def_insn)) == SET) | |
3113 | reg = SET_DEST (PATTERN (def_insn)); | |
3114 | else | |
3115 | abort (); | |
3116 | return ! reg_set_between_p (reg, NEXT_INSN (def_insn), insn); | |
3117 | } | |
3118 | else | |
3119 | return 0; | |
3120 | } | |
3121 | ||
3122 | return 0; | |
3123 | } | |
3124 | ||
3125 | /* Return non-zero if *ADDR_THIS_REG can only have one value at INSN. | |
3126 | The value returned is the number of definitions that reach INSN. | |
3127 | Returning a value of zero means that [maybe] more than one definition | |
3128 | reaches INSN and the caller can't perform whatever optimization it is | |
3129 | trying. i.e. it is always safe to return zero. */ | |
3130 | ||
3131 | static int | |
3132 | can_disregard_other_sets (addr_this_reg, insn, for_combine) | |
3133 | struct reg_set **addr_this_reg; | |
3134 | rtx insn; | |
3135 | int for_combine; | |
3136 | { | |
3137 | int number_of_reaching_defs = 0; | |
3138 | struct reg_set *this_reg = *addr_this_reg; | |
3139 | ||
3140 | while (this_reg) | |
3141 | { | |
3142 | if (def_reaches_here_p (insn, this_reg->insn)) | |
3143 | { | |
3144 | number_of_reaching_defs++; | |
3145 | /* Ignore parallels for now. */ | |
3146 | if (GET_CODE (PATTERN (this_reg->insn)) == PARALLEL) | |
3147 | return 0; | |
3148 | if (!for_combine | |
3149 | && (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER | |
3150 | || ! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)), | |
3151 | SET_SRC (PATTERN (insn))))) | |
3152 | { | |
3153 | /* A setting of the reg to a different value reaches INSN. */ | |
3154 | return 0; | |
3155 | } | |
3156 | if (number_of_reaching_defs > 1) | |
3157 | { | |
3158 | /* If in this setting the value the register is being | |
3159 | set to is equal to the previous value the register | |
3160 | was set to and this setting reaches the insn we are | |
3161 | trying to do the substitution on then we are ok. */ | |
3162 | ||
3163 | if (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER) | |
3164 | return 0; | |
3165 | if (! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)), | |
3166 | SET_SRC (PATTERN (insn)))) | |
3167 | return 0; | |
3168 | } | |
3169 | *addr_this_reg = this_reg; | |
3170 | } | |
3171 | ||
3172 | /* prev_this_reg = this_reg; */ | |
3173 | this_reg = this_reg->next; | |
3174 | } | |
3175 | ||
3176 | return number_of_reaching_defs; | |
3177 | } | |
3178 | ||
3179 | /* Expression computed by insn is available and the substitution is legal, | |
3180 | so try to perform the substitution. | |
3181 | ||
3182 | The result is non-zero if any changes were made. */ | |
3183 | ||
3184 | static int | |
3185 | handle_avail_expr (insn, expr) | |
3186 | rtx insn; | |
3187 | struct expr *expr; | |
3188 | { | |
3189 | rtx pat, insn_computes_expr; | |
3190 | rtx to; | |
3191 | struct reg_set *this_reg; | |
3192 | int found_setting, use_src; | |
3193 | int changed = 0; | |
3194 | ||
3195 | /* We only handle the case where one computation of the expression | |
3196 | reaches this instruction. */ | |
3197 | insn_computes_expr = computing_insn (expr, insn); | |
3198 | if (insn_computes_expr == NULL) | |
3199 | return 0; | |
3200 | ||
3201 | found_setting = 0; | |
3202 | use_src = 0; | |
3203 | ||
3204 | /* At this point we know only one computation of EXPR outside of this | |
3205 | block reaches this insn. Now try to find a register that the | |
3206 | expression is computed into. */ | |
3207 | ||
3208 | if (GET_CODE (SET_SRC (PATTERN (insn_computes_expr))) == REG) | |
3209 | { | |
3210 | /* This is the case when the available expression that reaches | |
3211 | here has already been handled as an available expression. */ | |
3212 | int regnum_for_replacing = REGNO (SET_SRC (PATTERN (insn_computes_expr))); | |
3213 | /* If the register was created by GCSE we can't use `reg_set_table', | |
3214 | however we know it's set only once. */ | |
3215 | if (regnum_for_replacing >= max_gcse_regno | |
3216 | /* If the register the expression is computed into is set only once, | |
3217 | or only one set reaches this insn, we can use it. */ | |
3218 | || (((this_reg = reg_set_table[regnum_for_replacing]), | |
3219 | this_reg->next == NULL) | |
3220 | || can_disregard_other_sets (&this_reg, insn, 0))) | |
3221 | { | |
3222 | use_src = 1; | |
3223 | found_setting = 1; | |
3224 | } | |
3225 | } | |
3226 | ||
3227 | if (!found_setting) | |
3228 | { | |
3229 | int regnum_for_replacing = REGNO (SET_DEST (PATTERN (insn_computes_expr))); | |
3230 | /* This shouldn't happen. */ | |
3231 | if (regnum_for_replacing >= max_gcse_regno) | |
3232 | abort (); | |
3233 | this_reg = reg_set_table[regnum_for_replacing]; | |
3234 | /* If the register the expression is computed into is set only once, | |
3235 | or only one set reaches this insn, use it. */ | |
3236 | if (this_reg->next == NULL | |
3237 | || can_disregard_other_sets (&this_reg, insn, 0)) | |
3238 | found_setting = 1; | |
3239 | } | |
3240 | ||
3241 | if (found_setting) | |
3242 | { | |
3243 | pat = PATTERN (insn); | |
3244 | if (use_src) | |
3245 | to = SET_SRC (PATTERN (insn_computes_expr)); | |
3246 | else | |
3247 | to = SET_DEST (PATTERN (insn_computes_expr)); | |
3248 | changed = validate_change (insn, &SET_SRC (pat), to, 0); | |
3249 | ||
3250 | /* We should be able to ignore the return code from validate_change but | |
3251 | to play it safe we check. */ | |
3252 | if (changed) | |
3253 | { | |
3254 | gcse_subst_count++; | |
3255 | if (gcse_file != NULL) | |
3256 | { | |
3257 | fprintf (gcse_file, "GCSE: Replacing the source in insn %d with reg %d %s insn %d\n", | |
3258 | INSN_UID (insn), REGNO (to), | |
3259 | use_src ? "from" : "set in", | |
3260 | INSN_UID (insn_computes_expr)); | |
3261 | } | |
3262 | ||
3263 | } | |
3264 | } | |
3265 | /* The register that the expr is computed into is set more than once. */ | |
3266 | else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/) | |
3267 | { | |
3268 | /* Insert an insn after insnx that copies the reg set in insnx | |
3269 | into a new pseudo register call this new register REGN. | |
3270 | From insnb until end of basic block or until REGB is set | |
3271 | replace all uses of REGB with REGN. */ | |
3272 | rtx new_insn; | |
3273 | ||
3274 | to = gen_reg_rtx (GET_MODE (SET_DEST (PATTERN (insn_computes_expr)))); | |
3275 | ||
3276 | /* Generate the new insn. */ | |
3277 | /* ??? If the change fails, we return 0, even though we created | |
3278 | an insn. I think this is ok. */ | |
9e6a5703 JC |
3279 | new_insn |
3280 | = emit_insn_after (gen_rtx_SET (VOIDmode, to, | |
3281 | SET_DEST (PATTERN (insn_computes_expr))), | |
7506f491 DE |
3282 | insn_computes_expr); |
3283 | /* Keep block number table up to date. */ | |
3284 | set_block_num (new_insn, BLOCK_NUM (insn_computes_expr)); | |
3285 | /* Keep register set table up to date. */ | |
3286 | record_one_set (REGNO (to), new_insn); | |
3287 | ||
3288 | gcse_create_count++; | |
3289 | if (gcse_file != NULL) | |
ac7c5af5 | 3290 | { |
7506f491 DE |
3291 | fprintf (gcse_file, "GCSE: Creating insn %d to copy value of reg %d, computed in insn %d,\n", |
3292 | INSN_UID (NEXT_INSN (insn_computes_expr)), | |
3293 | REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr)))), | |
3294 | INSN_UID (insn_computes_expr)); | |
3295 | fprintf (gcse_file, " into newly allocated reg %d\n", REGNO (to)); | |
ac7c5af5 | 3296 | } |
7506f491 DE |
3297 | |
3298 | pat = PATTERN (insn); | |
3299 | ||
3300 | /* Do register replacement for INSN. */ | |
3301 | changed = validate_change (insn, &SET_SRC (pat), | |
3302 | SET_DEST (PATTERN (NEXT_INSN (insn_computes_expr))), | |
3303 | 0); | |
3304 | ||
3305 | /* We should be able to ignore the return code from validate_change but | |
3306 | to play it safe we check. */ | |
3307 | if (changed) | |
3308 | { | |
3309 | gcse_subst_count++; | |
3310 | if (gcse_file != NULL) | |
3311 | { | |
3312 | fprintf (gcse_file, "GCSE: Replacing the source in insn %d with reg %d set in insn %d\n", | |
3313 | INSN_UID (insn), | |
3314 | REGNO (SET_DEST (PATTERN (NEXT_INSN (insn_computes_expr)))), | |
3315 | INSN_UID (insn_computes_expr)); | |
3316 | } | |
3317 | ||
3318 | } | |
3319 | } | |
3320 | ||
3321 | return changed; | |
3322 | } | |
3323 | ||
3324 | /* Perform classic GCSE. | |
3325 | This is called by one_classic_gcse_pass after all the dataflow analysis | |
3326 | has been done. | |
3327 | ||
3328 | The result is non-zero if a change was made. */ | |
3329 | ||
3330 | static int | |
3331 | classic_gcse () | |
3332 | { | |
3333 | int bb, changed; | |
3334 | rtx insn; | |
3335 | ||
3336 | /* Note we start at block 1. */ | |
3337 | ||
3338 | changed = 0; | |
3339 | for (bb = 1; bb < n_basic_blocks; bb++) | |
3340 | { | |
3341 | /* Reset tables used to keep track of what's still valid [since the | |
3342 | start of the block]. */ | |
3343 | reset_opr_set_tables (); | |
3344 | ||
3b413743 RH |
3345 | for (insn = BLOCK_HEAD (bb); |
3346 | insn != NULL && insn != NEXT_INSN (BLOCK_END (bb)); | |
7506f491 DE |
3347 | insn = NEXT_INSN (insn)) |
3348 | { | |
3349 | /* Is insn of form (set (pseudo-reg) ...)? */ | |
3350 | ||
3351 | if (GET_CODE (insn) == INSN | |
3352 | && GET_CODE (PATTERN (insn)) == SET | |
3353 | && GET_CODE (SET_DEST (PATTERN (insn))) == REG | |
3354 | && REGNO (SET_DEST (PATTERN (insn))) >= FIRST_PSEUDO_REGISTER) | |
3355 | { | |
3356 | rtx pat = PATTERN (insn); | |
3357 | rtx src = SET_SRC (pat); | |
3358 | struct expr *expr; | |
3359 | ||
3360 | if (want_to_gcse_p (src) | |
3361 | /* Is the expression recorded? */ | |
3362 | && ((expr = lookup_expr (src)) != NULL) | |
3363 | /* Is the expression available [at the start of the | |
3364 | block]? */ | |
3365 | && TEST_BIT (ae_in[bb], expr->bitmap_index) | |
3366 | /* Are the operands unchanged since the start of the | |
3367 | block? */ | |
3368 | && oprs_not_set_p (src, insn)) | |
3369 | changed |= handle_avail_expr (insn, expr); | |
3370 | } | |
3371 | ||
3372 | /* Keep track of everything modified by this insn. */ | |
3373 | /* ??? Need to be careful w.r.t. mods done to INSN. */ | |
3374 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
3375 | mark_oprs_set (insn); | |
ac7c5af5 | 3376 | } |
7506f491 DE |
3377 | } |
3378 | ||
3379 | return changed; | |
3380 | } | |
3381 | ||
3382 | /* Top level routine to perform one classic GCSE pass. | |
3383 | ||
3384 | Return non-zero if a change was made. */ | |
3385 | ||
3386 | static int | |
b5ce41ff | 3387 | one_classic_gcse_pass (pass) |
7506f491 DE |
3388 | int pass; |
3389 | { | |
3390 | int changed = 0; | |
3391 | ||
3392 | gcse_subst_count = 0; | |
3393 | gcse_create_count = 0; | |
3394 | ||
3395 | alloc_expr_hash_table (max_cuid); | |
3396 | alloc_rd_mem (n_basic_blocks, max_cuid); | |
b5ce41ff | 3397 | compute_expr_hash_table (); |
7506f491 DE |
3398 | if (gcse_file) |
3399 | dump_hash_table (gcse_file, "Expression", expr_hash_table, | |
3400 | expr_hash_table_size, n_exprs); | |
3401 | if (n_exprs > 0) | |
3402 | { | |
3403 | compute_kill_rd (); | |
3404 | compute_rd (); | |
3405 | alloc_avail_expr_mem (n_basic_blocks, n_exprs); | |
3406 | compute_ae_gen (); | |
a42cd965 | 3407 | compute_ae_kill (ae_gen, ae_kill); |
bd0eaec2 | 3408 | compute_available (ae_gen, ae_kill, ae_out, ae_in); |
7506f491 DE |
3409 | changed = classic_gcse (); |
3410 | free_avail_expr_mem (); | |
3411 | } | |
3412 | free_rd_mem (); | |
3413 | free_expr_hash_table (); | |
3414 | ||
3415 | if (gcse_file) | |
3416 | { | |
3417 | fprintf (gcse_file, "\n"); | |
3418 | fprintf (gcse_file, "GCSE of %s, pass %d: %d bytes needed, %d substs, %d insns created\n", | |
3419 | current_function_name, pass, | |
3420 | bytes_used, gcse_subst_count, gcse_create_count); | |
3421 | } | |
3422 | ||
3423 | return changed; | |
3424 | } | |
3425 | \f | |
3426 | /* Compute copy/constant propagation working variables. */ | |
3427 | ||
3428 | /* Local properties of assignments. */ | |
3429 | ||
3430 | static sbitmap *cprop_pavloc; | |
3431 | static sbitmap *cprop_absaltered; | |
3432 | ||
3433 | /* Global properties of assignments (computed from the local properties). */ | |
3434 | ||
3435 | static sbitmap *cprop_avin; | |
3436 | static sbitmap *cprop_avout; | |
3437 | ||
3438 | /* Allocate vars used for copy/const propagation. | |
3439 | N_BLOCKS is the number of basic blocks. | |
3440 | N_SETS is the number of sets. */ | |
3441 | ||
3442 | static void | |
3443 | alloc_cprop_mem (n_blocks, n_sets) | |
3444 | int n_blocks, n_sets; | |
3445 | { | |
3446 | cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets); | |
3447 | cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets); | |
3448 | ||
3449 | cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets); | |
3450 | cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets); | |
3451 | } | |
3452 | ||
3453 | /* Free vars used by copy/const propagation. */ | |
3454 | ||
3455 | static void | |
3456 | free_cprop_mem () | |
3457 | { | |
3458 | free (cprop_pavloc); | |
3459 | free (cprop_absaltered); | |
3460 | free (cprop_avin); | |
3461 | free (cprop_avout); | |
3462 | } | |
3463 | ||
7506f491 DE |
3464 | /* For each block, compute whether X is transparent. |
3465 | X is either an expression or an assignment [though we don't care which, | |
3466 | for this context an assignment is treated as an expression]. | |
3467 | For each block where an element of X is modified, set (SET_P == 1) or reset | |
3468 | (SET_P == 0) the INDX bit in BMAP. */ | |
3469 | ||
3470 | static void | |
3471 | compute_transp (x, indx, bmap, set_p) | |
3472 | rtx x; | |
3473 | int indx; | |
3474 | sbitmap *bmap; | |
3475 | int set_p; | |
3476 | { | |
3477 | int bb,i; | |
3478 | enum rtx_code code; | |
6f7d635c | 3479 | const char *fmt; |
7506f491 DE |
3480 | |
3481 | /* repeat is used to turn tail-recursion into iteration. */ | |
3482 | repeat: | |
3483 | ||
3484 | if (x == 0) | |
3485 | return; | |
3486 | ||
3487 | code = GET_CODE (x); | |
3488 | switch (code) | |
3489 | { | |
3490 | case REG: | |
3491 | { | |
3492 | reg_set *r; | |
3493 | int regno = REGNO (x); | |
3494 | ||
3495 | if (set_p) | |
3496 | { | |
3497 | if (regno < FIRST_PSEUDO_REGISTER) | |
3498 | { | |
3499 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3500 | if (TEST_BIT (reg_set_in_block[bb], regno)) | |
3501 | SET_BIT (bmap[bb], indx); | |
3502 | } | |
3503 | else | |
3504 | { | |
3505 | for (r = reg_set_table[regno]; r != NULL; r = r->next) | |
3506 | { | |
3507 | bb = BLOCK_NUM (r->insn); | |
3508 | SET_BIT (bmap[bb], indx); | |
3509 | } | |
3510 | } | |
3511 | } | |
3512 | else | |
3513 | { | |
3514 | if (regno < FIRST_PSEUDO_REGISTER) | |
3515 | { | |
3516 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3517 | if (TEST_BIT (reg_set_in_block[bb], regno)) | |
3518 | RESET_BIT (bmap[bb], indx); | |
3519 | } | |
3520 | else | |
3521 | { | |
3522 | for (r = reg_set_table[regno]; r != NULL; r = r->next) | |
3523 | { | |
3524 | bb = BLOCK_NUM (r->insn); | |
3525 | RESET_BIT (bmap[bb], indx); | |
3526 | } | |
3527 | } | |
3528 | } | |
3529 | return; | |
3530 | } | |
3531 | ||
3532 | case MEM: | |
3533 | if (set_p) | |
3534 | { | |
3535 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3536 | if (mem_set_in_block[bb]) | |
3537 | SET_BIT (bmap[bb], indx); | |
3538 | } | |
3539 | else | |
3540 | { | |
3541 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3542 | if (mem_set_in_block[bb]) | |
3543 | RESET_BIT (bmap[bb], indx); | |
3544 | } | |
3545 | x = XEXP (x, 0); | |
3546 | goto repeat; | |
3547 | ||
3548 | case PC: | |
3549 | case CC0: /*FIXME*/ | |
3550 | case CONST: | |
3551 | case CONST_INT: | |
3552 | case CONST_DOUBLE: | |
3553 | case SYMBOL_REF: | |
3554 | case LABEL_REF: | |
3555 | case ADDR_VEC: | |
3556 | case ADDR_DIFF_VEC: | |
3557 | return; | |
3558 | ||
3559 | default: | |
3560 | break; | |
3561 | } | |
3562 | ||
3563 | i = GET_RTX_LENGTH (code) - 1; | |
3564 | fmt = GET_RTX_FORMAT (code); | |
3565 | for (; i >= 0; i--) | |
3566 | { | |
3567 | if (fmt[i] == 'e') | |
3568 | { | |
3569 | rtx tem = XEXP (x, i); | |
3570 | ||
3571 | /* If we are about to do the last recursive call | |
3572 | needed at this level, change it into iteration. | |
3573 | This function is called enough to be worth it. */ | |
3574 | if (i == 0) | |
3575 | { | |
3576 | x = tem; | |
3577 | goto repeat; | |
3578 | } | |
3579 | compute_transp (tem, indx, bmap, set_p); | |
3580 | } | |
3581 | else if (fmt[i] == 'E') | |
3582 | { | |
3583 | int j; | |
3584 | for (j = 0; j < XVECLEN (x, i); j++) | |
3585 | compute_transp (XVECEXP (x, i, j), indx, bmap, set_p); | |
3586 | } | |
3587 | } | |
3588 | } | |
3589 | ||
7506f491 DE |
3590 | /* Top level routine to do the dataflow analysis needed by copy/const |
3591 | propagation. */ | |
3592 | ||
3593 | static void | |
3594 | compute_cprop_data () | |
3595 | { | |
b5ce41ff | 3596 | compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, 1); |
ce724250 JL |
3597 | compute_available (cprop_pavloc, cprop_absaltered, |
3598 | cprop_avout, cprop_avin); | |
7506f491 DE |
3599 | } |
3600 | \f | |
3601 | /* Copy/constant propagation. */ | |
3602 | ||
7506f491 DE |
3603 | /* Maximum number of register uses in an insn that we handle. */ |
3604 | #define MAX_USES 8 | |
3605 | ||
3606 | /* Table of uses found in an insn. | |
3607 | Allocated statically to avoid alloc/free complexity and overhead. */ | |
3608 | static struct reg_use reg_use_table[MAX_USES]; | |
3609 | ||
3610 | /* Index into `reg_use_table' while building it. */ | |
3611 | static int reg_use_count; | |
3612 | ||
3613 | /* Set up a list of register numbers used in INSN. | |
3614 | The found uses are stored in `reg_use_table'. | |
3615 | `reg_use_count' is initialized to zero before entry, and | |
3616 | contains the number of uses in the table upon exit. | |
3617 | ||
3618 | ??? If a register appears multiple times we will record it multiple | |
3619 | times. This doesn't hurt anything but it will slow things down. */ | |
3620 | ||
3621 | static void | |
3622 | find_used_regs (x) | |
3623 | rtx x; | |
3624 | { | |
3625 | int i; | |
3626 | enum rtx_code code; | |
6f7d635c | 3627 | const char *fmt; |
7506f491 DE |
3628 | |
3629 | /* repeat is used to turn tail-recursion into iteration. */ | |
3630 | repeat: | |
3631 | ||
3632 | if (x == 0) | |
3633 | return; | |
3634 | ||
3635 | code = GET_CODE (x); | |
3636 | switch (code) | |
3637 | { | |
3638 | case REG: | |
3639 | if (reg_use_count == MAX_USES) | |
3640 | return; | |
3641 | reg_use_table[reg_use_count].reg_rtx = x; | |
3642 | reg_use_count++; | |
3643 | return; | |
3644 | ||
3645 | case MEM: | |
3646 | x = XEXP (x, 0); | |
3647 | goto repeat; | |
3648 | ||
3649 | case PC: | |
3650 | case CC0: | |
3651 | case CONST: | |
3652 | case CONST_INT: | |
3653 | case CONST_DOUBLE: | |
3654 | case SYMBOL_REF: | |
3655 | case LABEL_REF: | |
3656 | case CLOBBER: | |
3657 | case ADDR_VEC: | |
3658 | case ADDR_DIFF_VEC: | |
3659 | case ASM_INPUT: /*FIXME*/ | |
3660 | return; | |
3661 | ||
3662 | case SET: | |
3663 | if (GET_CODE (SET_DEST (x)) == MEM) | |
3664 | find_used_regs (SET_DEST (x)); | |
3665 | x = SET_SRC (x); | |
3666 | goto repeat; | |
3667 | ||
3668 | default: | |
3669 | break; | |
3670 | } | |
3671 | ||
3672 | /* Recursively scan the operands of this expression. */ | |
3673 | ||
3674 | fmt = GET_RTX_FORMAT (code); | |
3675 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
3676 | { | |
3677 | if (fmt[i] == 'e') | |
3678 | { | |
3679 | /* If we are about to do the last recursive call | |
3680 | needed at this level, change it into iteration. | |
3681 | This function is called enough to be worth it. */ | |
3682 | if (i == 0) | |
3683 | { | |
3684 | x = XEXP (x, 0); | |
3685 | goto repeat; | |
3686 | } | |
3687 | find_used_regs (XEXP (x, i)); | |
3688 | } | |
3689 | else if (fmt[i] == 'E') | |
3690 | { | |
3691 | int j; | |
3692 | for (j = 0; j < XVECLEN (x, i); j++) | |
3693 | find_used_regs (XVECEXP (x, i, j)); | |
3694 | } | |
3695 | } | |
3696 | } | |
3697 | ||
3698 | /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO. | |
3699 | Returns non-zero is successful. */ | |
3700 | ||
3701 | static int | |
3702 | try_replace_reg (from, to, insn) | |
3703 | rtx from, to, insn; | |
3704 | { | |
e78d9500 JL |
3705 | /* If this fails we could try to simplify the result of the |
3706 | replacement and attempt to recognize the simplified insn. | |
3707 | ||
3708 | But we need a general simplify_rtx that doesn't have pass | |
3709 | specific state variables. I'm not aware of one at the moment. */ | |
7506f491 DE |
3710 | return validate_replace_src (from, to, insn); |
3711 | } | |
3712 | ||
3713 | /* Find a set of REGNO that is available on entry to INSN's block. | |
3714 | Returns NULL if not found. */ | |
3715 | ||
3716 | static struct expr * | |
3717 | find_avail_set (regno, insn) | |
3718 | int regno; | |
3719 | rtx insn; | |
3720 | { | |
cafba495 BS |
3721 | /* SET1 contains the last set found that can be returned to the caller for |
3722 | use in a substitution. */ | |
3723 | struct expr *set1 = 0; | |
3724 | ||
3725 | /* Loops are not possible here. To get a loop we would need two sets | |
3726 | available at the start of the block containing INSN. ie we would | |
3727 | need two sets like this available at the start of the block: | |
3728 | ||
3729 | (set (reg X) (reg Y)) | |
3730 | (set (reg Y) (reg X)) | |
3731 | ||
3732 | This can not happen since the set of (reg Y) would have killed the | |
3733 | set of (reg X) making it unavailable at the start of this block. */ | |
3734 | while (1) | |
3735 | { | |
3736 | rtx src; | |
3737 | struct expr *set = lookup_set (regno, NULL_RTX); | |
3738 | ||
3739 | /* Find a set that is available at the start of the block | |
3740 | which contains INSN. */ | |
3741 | while (set) | |
3742 | { | |
3743 | if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index)) | |
3744 | break; | |
3745 | set = next_set (regno, set); | |
3746 | } | |
7506f491 | 3747 | |
cafba495 BS |
3748 | /* If no available set was found we've reached the end of the |
3749 | (possibly empty) copy chain. */ | |
3750 | if (set == 0) | |
3751 | break; | |
3752 | ||
3753 | if (GET_CODE (set->expr) != SET) | |
3754 | abort (); | |
3755 | ||
3756 | src = SET_SRC (set->expr); | |
3757 | ||
3758 | /* We know the set is available. | |
3759 | Now check that SRC is ANTLOC (i.e. none of the source operands | |
3760 | have changed since the start of the block). | |
3761 | ||
3762 | If the source operand changed, we may still use it for the next | |
3763 | iteration of this loop, but we may not use it for substitutions. */ | |
3764 | if (CONSTANT_P (src) || oprs_not_set_p (src, insn)) | |
3765 | set1 = set; | |
3766 | ||
3767 | /* If the source of the set is anything except a register, then | |
3768 | we have reached the end of the copy chain. */ | |
3769 | if (GET_CODE (src) != REG) | |
7506f491 | 3770 | break; |
7506f491 | 3771 | |
cafba495 BS |
3772 | /* Follow the copy chain, ie start another iteration of the loop |
3773 | and see if we have an available copy into SRC. */ | |
3774 | regno = REGNO (src); | |
3775 | } | |
3776 | ||
3777 | /* SET1 holds the last set that was available and anticipatable at | |
3778 | INSN. */ | |
3779 | return set1; | |
7506f491 DE |
3780 | } |
3781 | ||
abd535b6 BS |
3782 | /* Subroutine of cprop_insn that tries to propagate constants into |
3783 | JUMP_INSNS. INSN must be a conditional jump; COPY is a copy of it | |
3784 | that we can use for substitutions. | |
3785 | REG_USED is the use we will try to replace, SRC is the constant we | |
3786 | will try to substitute for it. | |
3787 | Returns nonzero if a change was made. */ | |
3788 | static int | |
3789 | cprop_jump (insn, copy, reg_used, src) | |
3790 | rtx insn, copy; | |
3791 | struct reg_use *reg_used; | |
3792 | rtx src; | |
3793 | { | |
3794 | rtx set = PATTERN (copy); | |
3795 | rtx temp; | |
3796 | ||
3797 | /* Replace the register with the appropriate constant. */ | |
3798 | replace_rtx (SET_SRC (set), reg_used->reg_rtx, src); | |
3799 | ||
3800 | temp = simplify_ternary_operation (GET_CODE (SET_SRC (set)), | |
3801 | GET_MODE (SET_SRC (set)), | |
3802 | GET_MODE (XEXP (SET_SRC (set), 0)), | |
3803 | XEXP (SET_SRC (set), 0), | |
3804 | XEXP (SET_SRC (set), 1), | |
3805 | XEXP (SET_SRC (set), 2)); | |
3806 | ||
3807 | /* If no simplification can be made, then try the next | |
3808 | register. */ | |
3809 | if (temp == 0) | |
3810 | return 0; | |
3811 | ||
3812 | SET_SRC (set) = temp; | |
3813 | ||
3814 | /* That may have changed the structure of TEMP, so | |
3815 | force it to be rerecognized if it has not turned | |
3816 | into a nop or unconditional jump. */ | |
3817 | ||
3818 | INSN_CODE (copy) = -1; | |
3819 | if ((SET_DEST (set) == pc_rtx | |
3820 | && (SET_SRC (set) == pc_rtx | |
3821 | || GET_CODE (SET_SRC (set)) == LABEL_REF)) | |
3822 | || recog (PATTERN (copy), copy, NULL) >= 0) | |
3823 | { | |
3824 | /* This has either become an unconditional jump | |
3825 | or a nop-jump. We'd like to delete nop jumps | |
3826 | here, but doing so confuses gcse. So we just | |
3827 | make the replacement and let later passes | |
3828 | sort things out. */ | |
3829 | PATTERN (insn) = set; | |
3830 | INSN_CODE (insn) = -1; | |
3831 | ||
3832 | /* One less use of the label this insn used to jump to | |
3833 | if we turned this into a NOP jump. */ | |
3834 | if (SET_SRC (set) == pc_rtx && JUMP_LABEL (insn) != 0) | |
3835 | --LABEL_NUSES (JUMP_LABEL (insn)); | |
3836 | ||
3837 | /* If this has turned into an unconditional jump, | |
3838 | then put a barrier after it so that the unreachable | |
3839 | code will be deleted. */ | |
3840 | if (GET_CODE (SET_SRC (set)) == LABEL_REF) | |
3841 | emit_barrier_after (insn); | |
3842 | ||
3843 | run_jump_opt_after_gcse = 1; | |
3844 | ||
3845 | const_prop_count++; | |
3846 | if (gcse_file != NULL) | |
3847 | { | |
3848 | int regno = REGNO (reg_used->reg_rtx); | |
3849 | fprintf (gcse_file, "CONST-PROP: Replacing reg %d in insn %d with constant ", | |
3850 | regno, INSN_UID (insn)); | |
3851 | print_rtl (gcse_file, src); | |
3852 | fprintf (gcse_file, "\n"); | |
3853 | } | |
3854 | return 1; | |
3855 | } | |
3856 | return 0; | |
3857 | } | |
3858 | ||
3859 | #ifdef HAVE_cc0 | |
3860 | /* Subroutine of cprop_insn that tries to propagate constants into | |
3861 | JUMP_INSNS for machines that have CC0. INSN is a single set that | |
3862 | stores into CC0; the insn following it is a conditional jump. | |
3863 | REG_USED is the use we will try to replace, SRC is the constant we | |
3864 | will try to substitute for it. | |
3865 | Returns nonzero if a change was made. */ | |
3866 | static int | |
3867 | cprop_cc0_jump (insn, reg_used, src) | |
3868 | rtx insn; | |
3869 | struct reg_use *reg_used; | |
3870 | rtx src; | |
3871 | { | |
3872 | rtx jump = NEXT_INSN (insn); | |
3873 | rtx copy = copy_rtx (jump); | |
3874 | rtx set = PATTERN (copy); | |
3875 | ||
3876 | /* We need to copy the source of the cc0 setter, as cprop_jump is going to | |
3877 | substitute into it. */ | |
3878 | replace_rtx (SET_SRC (set), cc0_rtx, copy_rtx (SET_SRC (PATTERN (insn)))); | |
3879 | if (! cprop_jump (jump, copy, reg_used, src)) | |
3880 | return 0; | |
3881 | ||
3882 | /* If we succeeded, delete the cc0 setter. */ | |
3883 | PUT_CODE (insn, NOTE); | |
3884 | NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED; | |
3885 | NOTE_SOURCE_FILE (insn) = 0; | |
3886 | return 1; | |
3887 | } | |
3888 | #endif | |
3889 | ||
7506f491 DE |
3890 | /* Perform constant and copy propagation on INSN. |
3891 | The result is non-zero if a change was made. */ | |
3892 | ||
3893 | static int | |
b5ce41ff | 3894 | cprop_insn (insn, alter_jumps) |
7506f491 | 3895 | rtx insn; |
b5ce41ff | 3896 | int alter_jumps; |
7506f491 DE |
3897 | { |
3898 | struct reg_use *reg_used; | |
3899 | int changed = 0; | |
3900 | ||
e78d9500 JL |
3901 | /* Only propagate into SETs. Note that a conditional jump is a |
3902 | SET with pc_rtx as the destination. */ | |
3903 | if ((GET_CODE (insn) != INSN | |
3904 | && GET_CODE (insn) != JUMP_INSN) | |
7506f491 DE |
3905 | || GET_CODE (PATTERN (insn)) != SET) |
3906 | return 0; | |
3907 | ||
3908 | reg_use_count = 0; | |
3909 | find_used_regs (PATTERN (insn)); | |
3910 | ||
3911 | reg_used = ®_use_table[0]; | |
3912 | for ( ; reg_use_count > 0; reg_used++, reg_use_count--) | |
3913 | { | |
3914 | rtx pat, src; | |
3915 | struct expr *set; | |
3916 | int regno = REGNO (reg_used->reg_rtx); | |
3917 | ||
3918 | /* Ignore registers created by GCSE. | |
3919 | We do this because ... */ | |
3920 | if (regno >= max_gcse_regno) | |
3921 | continue; | |
3922 | ||
3923 | /* If the register has already been set in this block, there's | |
3924 | nothing we can do. */ | |
3925 | if (! oprs_not_set_p (reg_used->reg_rtx, insn)) | |
3926 | continue; | |
3927 | ||
3928 | /* Find an assignment that sets reg_used and is available | |
3929 | at the start of the block. */ | |
3930 | set = find_avail_set (regno, insn); | |
3931 | if (! set) | |
3932 | continue; | |
3933 | ||
3934 | pat = set->expr; | |
3935 | /* ??? We might be able to handle PARALLELs. Later. */ | |
3936 | if (GET_CODE (pat) != SET) | |
3937 | abort (); | |
3938 | src = SET_SRC (pat); | |
3939 | ||
e78d9500 | 3940 | /* Constant propagation. */ |
05f6f07c BS |
3941 | if (GET_CODE (src) == CONST_INT || GET_CODE (src) == CONST_DOUBLE |
3942 | || GET_CODE (src) == SYMBOL_REF) | |
7506f491 | 3943 | { |
e78d9500 JL |
3944 | /* Handle normal insns first. */ |
3945 | if (GET_CODE (insn) == INSN | |
3946 | && try_replace_reg (reg_used->reg_rtx, src, insn)) | |
7506f491 DE |
3947 | { |
3948 | changed = 1; | |
3949 | const_prop_count++; | |
3950 | if (gcse_file != NULL) | |
3951 | { | |
3952 | fprintf (gcse_file, "CONST-PROP: Replacing reg %d in insn %d with constant ", | |
3953 | regno, INSN_UID (insn)); | |
e78d9500 | 3954 | print_rtl (gcse_file, src); |
7506f491 DE |
3955 | fprintf (gcse_file, "\n"); |
3956 | } | |
3957 | ||
3958 | /* The original insn setting reg_used may or may not now be | |
3959 | deletable. We leave the deletion to flow. */ | |
3960 | } | |
e78d9500 JL |
3961 | |
3962 | /* Try to propagate a CONST_INT into a conditional jump. | |
3963 | We're pretty specific about what we will handle in this | |
3964 | code, we can extend this as necessary over time. | |
3965 | ||
3966 | Right now the insn in question must look like | |
abd535b6 | 3967 | (set (pc) (if_then_else ...)) */ |
b5ce41ff | 3968 | else if (alter_jumps |
6e9a3c38 JL |
3969 | && GET_CODE (insn) == JUMP_INSN |
3970 | && condjump_p (insn) | |
3971 | && ! simplejump_p (insn)) | |
abd535b6 BS |
3972 | changed |= cprop_jump (insn, copy_rtx (insn), reg_used, src); |
3973 | #ifdef HAVE_cc0 | |
3974 | /* Similar code for machines that use a pair of CC0 setter and | |
3975 | conditional jump insn. */ | |
3976 | else if (alter_jumps | |
3977 | && GET_CODE (PATTERN (insn)) == SET | |
3978 | && SET_DEST (PATTERN (insn)) == cc0_rtx | |
3979 | && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN | |
3980 | && condjump_p (NEXT_INSN (insn)) | |
3981 | && ! simplejump_p (NEXT_INSN (insn))) | |
3982 | changed |= cprop_cc0_jump (insn, reg_used, src); | |
3983 | #endif | |
7506f491 DE |
3984 | } |
3985 | else if (GET_CODE (src) == REG | |
3986 | && REGNO (src) >= FIRST_PSEUDO_REGISTER | |
3987 | && REGNO (src) != regno) | |
3988 | { | |
cafba495 | 3989 | if (try_replace_reg (reg_used->reg_rtx, src, insn)) |
7506f491 | 3990 | { |
cafba495 BS |
3991 | changed = 1; |
3992 | copy_prop_count++; | |
3993 | if (gcse_file != NULL) | |
7506f491 | 3994 | { |
cafba495 BS |
3995 | fprintf (gcse_file, "COPY-PROP: Replacing reg %d in insn %d with reg %d\n", |
3996 | regno, INSN_UID (insn), REGNO (src)); | |
7506f491 | 3997 | } |
cafba495 BS |
3998 | |
3999 | /* The original insn setting reg_used may or may not now be | |
4000 | deletable. We leave the deletion to flow. */ | |
4001 | /* FIXME: If it turns out that the insn isn't deletable, | |
4002 | then we may have unnecessarily extended register lifetimes | |
4003 | and made things worse. */ | |
7506f491 DE |
4004 | } |
4005 | } | |
4006 | } | |
4007 | ||
4008 | return changed; | |
4009 | } | |
4010 | ||
4011 | /* Forward propagate copies. | |
4012 | This includes copies and constants. | |
4013 | Return non-zero if a change was made. */ | |
4014 | ||
4015 | static int | |
b5ce41ff JL |
4016 | cprop (alter_jumps) |
4017 | int alter_jumps; | |
7506f491 DE |
4018 | { |
4019 | int bb, changed; | |
4020 | rtx insn; | |
4021 | ||
4022 | /* Note we start at block 1. */ | |
4023 | ||
4024 | changed = 0; | |
4025 | for (bb = 1; bb < n_basic_blocks; bb++) | |
4026 | { | |
4027 | /* Reset tables used to keep track of what's still valid [since the | |
4028 | start of the block]. */ | |
4029 | reset_opr_set_tables (); | |
4030 | ||
3b413743 RH |
4031 | for (insn = BLOCK_HEAD (bb); |
4032 | insn != NULL && insn != NEXT_INSN (BLOCK_END (bb)); | |
7506f491 DE |
4033 | insn = NEXT_INSN (insn)) |
4034 | { | |
4035 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
4036 | { | |
b5ce41ff | 4037 | changed |= cprop_insn (insn, alter_jumps); |
7506f491 DE |
4038 | |
4039 | /* Keep track of everything modified by this insn. */ | |
abd535b6 BS |
4040 | /* ??? Need to be careful w.r.t. mods done to INSN. Don't |
4041 | call mark_oprs_set if we turned the insn into a NOTE. */ | |
4042 | if (GET_CODE (insn) != NOTE) | |
4043 | mark_oprs_set (insn); | |
7506f491 | 4044 | } |
ac7c5af5 | 4045 | } |
7506f491 DE |
4046 | } |
4047 | ||
4048 | if (gcse_file != NULL) | |
4049 | fprintf (gcse_file, "\n"); | |
4050 | ||
4051 | return changed; | |
4052 | } | |
4053 | ||
4054 | /* Perform one copy/constant propagation pass. | |
4055 | F is the first insn in the function. | |
4056 | PASS is the pass count. */ | |
4057 | ||
4058 | static int | |
b5ce41ff | 4059 | one_cprop_pass (pass, alter_jumps) |
7506f491 | 4060 | int pass; |
b5ce41ff | 4061 | int alter_jumps; |
7506f491 DE |
4062 | { |
4063 | int changed = 0; | |
4064 | ||
4065 | const_prop_count = 0; | |
4066 | copy_prop_count = 0; | |
4067 | ||
4068 | alloc_set_hash_table (max_cuid); | |
b5ce41ff | 4069 | compute_set_hash_table (); |
7506f491 DE |
4070 | if (gcse_file) |
4071 | dump_hash_table (gcse_file, "SET", set_hash_table, set_hash_table_size, | |
4072 | n_sets); | |
4073 | if (n_sets > 0) | |
4074 | { | |
4075 | alloc_cprop_mem (n_basic_blocks, n_sets); | |
4076 | compute_cprop_data (); | |
b5ce41ff | 4077 | changed = cprop (alter_jumps); |
7506f491 DE |
4078 | free_cprop_mem (); |
4079 | } | |
4080 | free_set_hash_table (); | |
4081 | ||
4082 | if (gcse_file) | |
4083 | { | |
4084 | fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, %d const props, %d copy props\n", | |
4085 | current_function_name, pass, | |
4086 | bytes_used, const_prop_count, copy_prop_count); | |
4087 | fprintf (gcse_file, "\n"); | |
4088 | } | |
4089 | ||
4090 | return changed; | |
4091 | } | |
4092 | \f | |
a65f3558 | 4093 | /* Compute PRE+LCM working variables. */ |
7506f491 DE |
4094 | |
4095 | /* Local properties of expressions. */ | |
4096 | /* Nonzero for expressions that are transparent in the block. */ | |
a65f3558 | 4097 | static sbitmap *transp; |
7506f491 | 4098 | |
5c35539b RH |
4099 | /* Nonzero for expressions that are transparent at the end of the block. |
4100 | This is only zero for expressions killed by abnormal critical edge | |
4101 | created by a calls. */ | |
a65f3558 | 4102 | static sbitmap *transpout; |
5c35539b | 4103 | |
a65f3558 JL |
4104 | /* Nonzero for expressions that are computed (available) in the block. */ |
4105 | static sbitmap *comp; | |
7506f491 | 4106 | |
a65f3558 JL |
4107 | /* Nonzero for expressions that are locally anticipatable in the block. */ |
4108 | static sbitmap *antloc; | |
7506f491 | 4109 | |
a65f3558 JL |
4110 | /* Nonzero for expressions where this block is an optimal computation |
4111 | point. */ | |
4112 | static sbitmap *pre_optimal; | |
5c35539b | 4113 | |
a65f3558 JL |
4114 | /* Nonzero for expressions which are redundant in a particular block. */ |
4115 | static sbitmap *pre_redundant; | |
7506f491 | 4116 | |
a42cd965 AM |
4117 | /* Nonzero for expressions which should be inserted on a specific edge. */ |
4118 | static sbitmap *pre_insert_map; | |
4119 | ||
4120 | /* Nonzero for expressions which should be deleted in a specific block. */ | |
4121 | static sbitmap *pre_delete_map; | |
4122 | ||
4123 | /* Contains the edge_list returned by pre_edge_lcm. */ | |
4124 | static struct edge_list *edge_list; | |
4125 | ||
a65f3558 | 4126 | static sbitmap *temp_bitmap; |
7506f491 | 4127 | |
a65f3558 JL |
4128 | /* Redundant insns. */ |
4129 | static sbitmap pre_redundant_insns; | |
7506f491 | 4130 | |
a65f3558 | 4131 | /* Allocate vars used for PRE analysis. */ |
7506f491 DE |
4132 | |
4133 | static void | |
a65f3558 JL |
4134 | alloc_pre_mem (n_blocks, n_exprs) |
4135 | int n_blocks, n_exprs; | |
7506f491 | 4136 | { |
a65f3558 JL |
4137 | transp = sbitmap_vector_alloc (n_blocks, n_exprs); |
4138 | comp = sbitmap_vector_alloc (n_blocks, n_exprs); | |
4139 | antloc = sbitmap_vector_alloc (n_blocks, n_exprs); | |
a65f3558 | 4140 | temp_bitmap = sbitmap_vector_alloc (n_blocks, n_exprs); |
5faf03ae | 4141 | |
a42cd965 AM |
4142 | pre_optimal = NULL; |
4143 | pre_redundant = NULL; | |
4144 | pre_insert_map = NULL; | |
4145 | pre_delete_map = NULL; | |
4146 | ae_in = NULL; | |
4147 | ae_out = NULL; | |
4148 | u_bitmap = NULL; | |
a65f3558 | 4149 | transpout = sbitmap_vector_alloc (n_blocks, n_exprs); |
a42cd965 AM |
4150 | ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs); |
4151 | /* pre_insert and pre_delete are allocated later. */ | |
7506f491 DE |
4152 | } |
4153 | ||
a65f3558 | 4154 | /* Free vars used for PRE analysis. */ |
7506f491 DE |
4155 | |
4156 | static void | |
a65f3558 | 4157 | free_pre_mem () |
7506f491 | 4158 | { |
a65f3558 JL |
4159 | free (transp); |
4160 | free (comp); | |
4161 | free (antloc); | |
5faf03ae | 4162 | free (temp_bitmap); |
7506f491 | 4163 | |
a42cd965 AM |
4164 | if (pre_optimal) |
4165 | free (pre_optimal); | |
4166 | if (pre_redundant) | |
4167 | free (pre_redundant); | |
4168 | if (pre_insert_map) | |
4169 | free (pre_insert_map); | |
4170 | if (pre_delete_map) | |
4171 | free (pre_delete_map); | |
4172 | if (transpout) | |
4173 | free (transpout); | |
4174 | ||
4175 | if (ae_in) | |
4176 | free (ae_in); | |
4177 | if (ae_out) | |
4178 | free (ae_out); | |
4179 | if (ae_kill) | |
4180 | free (ae_kill); | |
4181 | if (u_bitmap) | |
4182 | free (u_bitmap); | |
4183 | ||
4184 | transp = comp = antloc = NULL; | |
4185 | pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL; | |
4186 | transpout = ae_in = ae_out = ae_kill = NULL; | |
4187 | u_bitmap = NULL; | |
4188 | ||
7506f491 DE |
4189 | } |
4190 | ||
4191 | /* Top level routine to do the dataflow analysis needed by PRE. */ | |
4192 | ||
4193 | static void | |
4194 | compute_pre_data () | |
4195 | { | |
a65f3558 JL |
4196 | compute_local_properties (transp, comp, antloc, 0); |
4197 | compute_transpout (); | |
a42cd965 AM |
4198 | sbitmap_vector_zero (ae_kill, n_basic_blocks); |
4199 | compute_ae_kill (comp, ae_kill); | |
4200 | edge_list = pre_edge_lcm (gcse_file, n_exprs, transp, comp, antloc, | |
4201 | ae_kill, &pre_insert_map, &pre_delete_map); | |
7506f491 | 4202 | } |
a65f3558 | 4203 | |
7506f491 DE |
4204 | \f |
4205 | /* PRE utilities */ | |
4206 | ||
a65f3558 JL |
4207 | /* Return non-zero if an occurrence of expression EXPR in OCCR_BB would reach |
4208 | block BB. | |
7506f491 DE |
4209 | |
4210 | VISITED is a pointer to a working buffer for tracking which BB's have | |
4211 | been visited. It is NULL for the top-level call. | |
4212 | ||
4213 | We treat reaching expressions that go through blocks containing the same | |
4214 | reaching expression as "not reaching". E.g. if EXPR is generated in blocks | |
4215 | 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block | |
4216 | 2 as not reaching. The intent is to improve the probability of finding | |
4217 | only one reaching expression and to reduce register lifetimes by picking | |
4218 | the closest such expression. */ | |
4219 | ||
4220 | static int | |
89e606c9 | 4221 | pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited) |
a65f3558 | 4222 | int occr_bb; |
7506f491 DE |
4223 | struct expr *expr; |
4224 | int bb; | |
4225 | char *visited; | |
4226 | { | |
36349f8b | 4227 | edge pred; |
7506f491 | 4228 | |
36349f8b | 4229 | for (pred = BASIC_BLOCK (bb)->pred; pred != NULL; pred = pred->pred_next) |
7506f491 | 4230 | { |
36349f8b | 4231 | int pred_bb = pred->src->index; |
7506f491 | 4232 | |
36349f8b | 4233 | if (pred->src == ENTRY_BLOCK_PTR |
7506f491 DE |
4234 | /* Has predecessor has already been visited? */ |
4235 | || visited[pred_bb]) | |
ac7c5af5 | 4236 | { |
7506f491 DE |
4237 | /* Nothing to do. */ |
4238 | } | |
4239 | /* Does this predecessor generate this expression? */ | |
89e606c9 | 4240 | else if (TEST_BIT (comp[pred_bb], expr->bitmap_index)) |
7506f491 DE |
4241 | { |
4242 | /* Is this the occurrence we're looking for? | |
4243 | Note that there's only one generating occurrence per block | |
4244 | so we just need to check the block number. */ | |
a65f3558 | 4245 | if (occr_bb == pred_bb) |
7506f491 DE |
4246 | return 1; |
4247 | visited[pred_bb] = 1; | |
4248 | } | |
4249 | /* Ignore this predecessor if it kills the expression. */ | |
a65f3558 | 4250 | else if (! TEST_BIT (transp[pred_bb], expr->bitmap_index)) |
7506f491 DE |
4251 | visited[pred_bb] = 1; |
4252 | /* Neither gen nor kill. */ | |
4253 | else | |
ac7c5af5 | 4254 | { |
7506f491 | 4255 | visited[pred_bb] = 1; |
89e606c9 | 4256 | if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited)) |
7506f491 | 4257 | return 1; |
ac7c5af5 | 4258 | } |
7506f491 DE |
4259 | } |
4260 | ||
4261 | /* All paths have been checked. */ | |
4262 | return 0; | |
4263 | } | |
283a2545 RL |
4264 | |
4265 | /* The wrapper for pre_expr_reaches_here_work that ensures that any | |
4266 | memory allocated for that function is returned. */ | |
4267 | ||
4268 | static int | |
89e606c9 | 4269 | pre_expr_reaches_here_p (occr_bb, expr, bb) |
283a2545 RL |
4270 | int occr_bb; |
4271 | struct expr *expr; | |
4272 | int bb; | |
283a2545 RL |
4273 | { |
4274 | int rval; | |
4275 | char * visited = (char *) xcalloc (n_basic_blocks, 1); | |
4276 | ||
89e606c9 | 4277 | rval = pre_expr_reaches_here_p_work(occr_bb, expr, bb, visited); |
283a2545 RL |
4278 | |
4279 | free (visited); | |
4280 | ||
4281 | return (rval); | |
4282 | } | |
7506f491 | 4283 | \f |
a42cd965 AM |
4284 | |
4285 | /* Given an expr, generate RTL which we can insert at the end of a BB, | |
4286 | or on an edge. Set the block number of any insns generated to | |
4287 | the value of BB. */ | |
4288 | ||
4289 | static rtx | |
4290 | process_insert_insn (expr) | |
4291 | struct expr *expr; | |
4292 | { | |
4293 | rtx reg = expr->reaching_reg; | |
4294 | rtx pat, copied_expr; | |
4295 | rtx first_new_insn; | |
4296 | ||
4297 | start_sequence (); | |
4298 | copied_expr = copy_rtx (expr->expr); | |
4299 | emit_move_insn (reg, copied_expr); | |
4300 | first_new_insn = get_insns (); | |
4301 | pat = gen_sequence (); | |
4302 | end_sequence (); | |
4303 | ||
4304 | return pat; | |
4305 | } | |
4306 | ||
a65f3558 JL |
4307 | /* Add EXPR to the end of basic block BB. |
4308 | ||
4309 | This is used by both the PRE and code hoisting. | |
4310 | ||
4311 | For PRE, we want to verify that the expr is either transparent | |
4312 | or locally anticipatable in the target block. This check makes | |
4313 | no sense for code hoisting. */ | |
7506f491 DE |
4314 | |
4315 | static void | |
a65f3558 | 4316 | insert_insn_end_bb (expr, bb, pre) |
7506f491 DE |
4317 | struct expr *expr; |
4318 | int bb; | |
a65f3558 | 4319 | int pre; |
7506f491 DE |
4320 | { |
4321 | rtx insn = BLOCK_END (bb); | |
4322 | rtx new_insn; | |
4323 | rtx reg = expr->reaching_reg; | |
4324 | int regno = REGNO (reg); | |
a42cd965 | 4325 | rtx pat; |
7506f491 | 4326 | |
a42cd965 | 4327 | pat = process_insert_insn (expr); |
7506f491 DE |
4328 | |
4329 | /* If the last insn is a jump, insert EXPR in front [taking care to | |
4330 | handle cc0, etc. properly]. */ | |
4331 | ||
4332 | if (GET_CODE (insn) == JUMP_INSN) | |
4333 | { | |
50b2596f | 4334 | #ifdef HAVE_cc0 |
7506f491 | 4335 | rtx note; |
50b2596f | 4336 | #endif |
7506f491 DE |
4337 | |
4338 | /* If this is a jump table, then we can't insert stuff here. Since | |
4339 | we know the previous real insn must be the tablejump, we insert | |
4340 | the new instruction just before the tablejump. */ | |
4341 | if (GET_CODE (PATTERN (insn)) == ADDR_VEC | |
4342 | || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) | |
4343 | insn = prev_real_insn (insn); | |
4344 | ||
4345 | #ifdef HAVE_cc0 | |
4346 | /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts | |
4347 | if cc0 isn't set. */ | |
4348 | note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX); | |
4349 | if (note) | |
4350 | insn = XEXP (note, 0); | |
4351 | else | |
4352 | { | |
4353 | rtx maybe_cc0_setter = prev_nonnote_insn (insn); | |
4354 | if (maybe_cc0_setter | |
4355 | && GET_RTX_CLASS (GET_CODE (maybe_cc0_setter)) == 'i' | |
4356 | && sets_cc0_p (PATTERN (maybe_cc0_setter))) | |
4357 | insn = maybe_cc0_setter; | |
4358 | } | |
4359 | #endif | |
4360 | /* FIXME: What if something in cc0/jump uses value set in new insn? */ | |
4361 | new_insn = emit_insn_before (pat, insn); | |
4362 | if (BLOCK_HEAD (bb) == insn) | |
4363 | BLOCK_HEAD (bb) = new_insn; | |
3947e2f9 RH |
4364 | } |
4365 | /* Likewise if the last insn is a call, as will happen in the presence | |
4366 | of exception handling. */ | |
5c35539b | 4367 | else if (GET_CODE (insn) == CALL_INSN) |
3947e2f9 RH |
4368 | { |
4369 | HARD_REG_SET parm_regs; | |
4370 | int nparm_regs; | |
4371 | rtx p; | |
4372 | ||
4373 | /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers, | |
4374 | we search backward and place the instructions before the first | |
4375 | parameter is loaded. Do this for everyone for consistency and a | |
4376 | presumtion that we'll get better code elsewhere as well. */ | |
4377 | ||
4378 | /* It should always be the case that we can put these instructions | |
a65f3558 JL |
4379 | anywhere in the basic block with performing PRE optimizations. |
4380 | Check this. */ | |
4381 | if (pre | |
4382 | && !TEST_BIT (antloc[bb], expr->bitmap_index) | |
4383 | && !TEST_BIT (transp[bb], expr->bitmap_index)) | |
3947e2f9 RH |
4384 | abort (); |
4385 | ||
4386 | /* Since different machines initialize their parameter registers | |
4387 | in different orders, assume nothing. Collect the set of all | |
4388 | parameter registers. */ | |
4389 | CLEAR_HARD_REG_SET (parm_regs); | |
4390 | nparm_regs = 0; | |
4391 | for (p = CALL_INSN_FUNCTION_USAGE (insn); p ; p = XEXP (p, 1)) | |
4392 | if (GET_CODE (XEXP (p, 0)) == USE | |
4393 | && GET_CODE (XEXP (XEXP (p, 0), 0)) == REG) | |
4394 | { | |
4395 | int regno = REGNO (XEXP (XEXP (p, 0), 0)); | |
4396 | if (regno >= FIRST_PSEUDO_REGISTER) | |
5c35539b | 4397 | abort (); |
3947e2f9 RH |
4398 | SET_HARD_REG_BIT (parm_regs, regno); |
4399 | nparm_regs++; | |
4400 | } | |
4401 | ||
4402 | /* Search backward for the first set of a register in this set. */ | |
4403 | while (nparm_regs && BLOCK_HEAD (bb) != insn) | |
4404 | { | |
4405 | insn = PREV_INSN (insn); | |
4406 | p = single_set (insn); | |
4407 | if (p && GET_CODE (SET_DEST (p)) == REG | |
4408 | && REGNO (SET_DEST (p)) < FIRST_PSEUDO_REGISTER | |
4409 | && TEST_HARD_REG_BIT (parm_regs, REGNO (SET_DEST (p)))) | |
4410 | { | |
4411 | CLEAR_HARD_REG_BIT (parm_regs, REGNO (SET_DEST (p))); | |
4412 | nparm_regs--; | |
4413 | } | |
4414 | } | |
4415 | ||
b1d26727 JL |
4416 | /* If we found all the parameter loads, then we want to insert |
4417 | before the first parameter load. | |
4418 | ||
4419 | If we did not find all the parameter loads, then we might have | |
4420 | stopped on the head of the block, which could be a CODE_LABEL. | |
4421 | If we inserted before the CODE_LABEL, then we would be putting | |
4422 | the insn in the wrong basic block. In that case, put the insn | |
4423 | after the CODE_LABEL. | |
4424 | ||
4425 | ?!? Do we need to account for NOTE_INSN_BASIC_BLOCK here? */ | |
4426 | if (GET_CODE (insn) != CODE_LABEL) | |
4427 | { | |
4428 | new_insn = emit_insn_before (pat, insn); | |
4429 | if (BLOCK_HEAD (bb) == insn) | |
4430 | BLOCK_HEAD (bb) = new_insn; | |
4431 | } | |
4432 | else | |
4433 | { | |
4434 | new_insn = emit_insn_after (pat, insn); | |
4435 | } | |
7506f491 DE |
4436 | } |
4437 | else | |
4438 | { | |
4439 | new_insn = emit_insn_after (pat, insn); | |
4440 | BLOCK_END (bb) = new_insn; | |
7506f491 DE |
4441 | } |
4442 | ||
a65f3558 JL |
4443 | /* Keep block number table up to date. |
4444 | Note, PAT could be a multiple insn sequence, we have to make | |
4445 | sure that each insn in the sequence is handled. */ | |
4446 | if (GET_CODE (pat) == SEQUENCE) | |
4447 | { | |
4448 | int i; | |
4449 | ||
4450 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
4451 | { | |
4452 | rtx insn = XVECEXP (pat, 0, i); | |
4453 | set_block_num (insn, bb); | |
4454 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
4455 | add_label_notes (PATTERN (insn), new_insn); | |
84832317 | 4456 | note_stores (PATTERN (insn), record_set_info, insn); |
a65f3558 JL |
4457 | } |
4458 | } | |
4459 | else | |
4460 | { | |
4461 | add_label_notes (SET_SRC (pat), new_insn); | |
4462 | set_block_num (new_insn, bb); | |
4463 | /* Keep register set table up to date. */ | |
4464 | record_one_set (regno, new_insn); | |
4465 | } | |
3947e2f9 | 4466 | |
7506f491 DE |
4467 | gcse_create_count++; |
4468 | ||
4469 | if (gcse_file) | |
4470 | { | |
a65f3558 | 4471 | fprintf (gcse_file, "PRE/HOIST: end of bb %d, insn %d, copying expression %d to reg %d\n", |
7506f491 DE |
4472 | bb, INSN_UID (new_insn), expr->bitmap_index, regno); |
4473 | } | |
4474 | } | |
4475 | ||
a42cd965 AM |
4476 | /* Insert partially redundant expressions on edges in the CFG to make |
4477 | the expressions fully redundant. */ | |
7506f491 | 4478 | |
a42cd965 AM |
4479 | static int |
4480 | pre_edge_insert (edge_list, index_map) | |
4481 | struct edge_list *edge_list; | |
7506f491 DE |
4482 | struct expr **index_map; |
4483 | { | |
a42cd965 | 4484 | int e, i, num_edges, set_size, did_insert = 0; |
a65f3558 JL |
4485 | sbitmap *inserted; |
4486 | ||
a42cd965 AM |
4487 | /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge |
4488 | if it reaches any of the deleted expressions. */ | |
7506f491 | 4489 | |
a42cd965 AM |
4490 | set_size = pre_insert_map[0]->size; |
4491 | num_edges = NUM_EDGES (edge_list); | |
4492 | inserted = sbitmap_vector_alloc (num_edges, n_exprs); | |
4493 | sbitmap_vector_zero (inserted, num_edges); | |
7506f491 | 4494 | |
a42cd965 | 4495 | for (e = 0; e < num_edges; e++) |
7506f491 DE |
4496 | { |
4497 | int indx; | |
a42cd965 AM |
4498 | basic_block pred = INDEX_EDGE_PRED_BB (edge_list, e); |
4499 | int bb = pred->index; | |
a65f3558 | 4500 | |
a65f3558 | 4501 | for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS) |
7506f491 | 4502 | { |
a42cd965 | 4503 | SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i]; |
7506f491 | 4504 | int j; |
7506f491 | 4505 | |
a65f3558 | 4506 | for (j = indx; insert && j < n_exprs; j++, insert >>= 1) |
7506f491 | 4507 | { |
a65f3558 JL |
4508 | if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX) |
4509 | { | |
4510 | struct expr *expr = index_map[j]; | |
4511 | struct occr *occr; | |
4512 | ||
4513 | /* Now look at each deleted occurence of this expression. */ | |
4514 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
4515 | { | |
4516 | if (! occr->deleted_p) | |
4517 | continue; | |
4518 | ||
a42cd965 AM |
4519 | /* Insert this expression on this edge if if it would |
4520 | reach the deleted occurence in BB. */ | |
89e606c9 | 4521 | if (!TEST_BIT (inserted[e], j)) |
a65f3558 | 4522 | { |
a42cd965 AM |
4523 | rtx insn; |
4524 | edge eg = INDEX_EDGE (edge_list, e); | |
4525 | /* We can't insert anything on an abnormal | |
4526 | and critical edge, so we insert the | |
4527 | insn at the end of the previous block. There | |
4528 | are several alternatives detailed in | |
4529 | Morgans book P277 (sec 10.5) for handling | |
4530 | this situation. This one is easiest for now. */ | |
4531 | ||
4532 | if ((eg->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL) | |
4533 | { | |
4534 | insert_insn_end_bb (index_map[j], bb, 0); | |
4535 | } | |
4536 | else | |
4537 | { | |
4538 | insn = process_insert_insn (index_map[j]); | |
4539 | insert_insn_on_edge (insn, eg); | |
4540 | } | |
4541 | if (gcse_file) | |
4542 | { | |
4543 | fprintf (gcse_file, | |
4544 | "PRE/HOIST: edge (%d,%d), copy expression %d\n", | |
4545 | bb, | |
4546 | INDEX_EDGE_SUCC_BB (edge_list, e)->index, expr->bitmap_index); | |
4547 | } | |
4548 | SET_BIT (inserted[e], j); | |
4549 | did_insert = 1; | |
4550 | gcse_create_count++; | |
a65f3558 JL |
4551 | } |
4552 | } | |
4553 | } | |
7506f491 DE |
4554 | } |
4555 | } | |
4556 | } | |
5faf03ae MM |
4557 | |
4558 | /* Clean up. */ | |
4559 | free (inserted); | |
4560 | ||
a42cd965 | 4561 | return did_insert; |
7506f491 DE |
4562 | } |
4563 | ||
4564 | /* Copy the result of INSN to REG. | |
4565 | INDX is the expression number. */ | |
4566 | ||
4567 | static void | |
4568 | pre_insert_copy_insn (expr, insn) | |
4569 | struct expr *expr; | |
4570 | rtx insn; | |
4571 | { | |
4572 | rtx reg = expr->reaching_reg; | |
4573 | int regno = REGNO (reg); | |
4574 | int indx = expr->bitmap_index; | |
4575 | rtx set = single_set (insn); | |
4576 | rtx new_insn; | |
a42cd965 | 4577 | int bb = BLOCK_NUM (insn); |
7506f491 DE |
4578 | |
4579 | if (!set) | |
4580 | abort (); | |
9e6a5703 | 4581 | new_insn = emit_insn_after (gen_rtx_SET (VOIDmode, reg, SET_DEST (set)), |
7506f491 DE |
4582 | insn); |
4583 | /* Keep block number table up to date. */ | |
a42cd965 | 4584 | set_block_num (new_insn, bb); |
7506f491 DE |
4585 | /* Keep register set table up to date. */ |
4586 | record_one_set (regno, new_insn); | |
a42cd965 AM |
4587 | if (insn == BLOCK_END (bb)) |
4588 | BLOCK_END (bb) = new_insn; | |
7506f491 DE |
4589 | |
4590 | gcse_create_count++; | |
4591 | ||
4592 | if (gcse_file) | |
a42cd965 AM |
4593 | fprintf (gcse_file, |
4594 | "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n", | |
4595 | BLOCK_NUM (insn), INSN_UID (new_insn), indx, | |
4596 | INSN_UID (insn), regno); | |
7506f491 DE |
4597 | } |
4598 | ||
4599 | /* Copy available expressions that reach the redundant expression | |
4600 | to `reaching_reg'. */ | |
4601 | ||
4602 | static void | |
4603 | pre_insert_copies () | |
4604 | { | |
36f0e0a6 | 4605 | int i; |
a65f3558 | 4606 | |
7506f491 DE |
4607 | /* For each available expression in the table, copy the result to |
4608 | `reaching_reg' if the expression reaches a deleted one. | |
4609 | ||
4610 | ??? The current algorithm is rather brute force. | |
4611 | Need to do some profiling. */ | |
4612 | ||
4613 | for (i = 0; i < expr_hash_table_size; i++) | |
4614 | { | |
4615 | struct expr *expr; | |
4616 | ||
4617 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
4618 | { | |
4619 | struct occr *occr; | |
4620 | ||
4621 | /* If the basic block isn't reachable, PPOUT will be TRUE. | |
4622 | However, we don't want to insert a copy here because the | |
4623 | expression may not really be redundant. So only insert | |
4624 | an insn if the expression was deleted. | |
4625 | This test also avoids further processing if the expression | |
4626 | wasn't deleted anywhere. */ | |
4627 | if (expr->reaching_reg == NULL) | |
4628 | continue; | |
4629 | ||
4630 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
4631 | { | |
4632 | struct occr *avail; | |
4633 | ||
4634 | if (! occr->deleted_p) | |
4635 | continue; | |
4636 | ||
4637 | for (avail = expr->avail_occr; avail != NULL; avail = avail->next) | |
4638 | { | |
4639 | rtx insn = avail->insn; | |
4640 | ||
4641 | /* No need to handle this one if handled already. */ | |
4642 | if (avail->copied_p) | |
4643 | continue; | |
4644 | /* Don't handle this one if it's a redundant one. */ | |
a65f3558 | 4645 | if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn))) |
7506f491 DE |
4646 | continue; |
4647 | /* Or if the expression doesn't reach the deleted one. */ | |
a65f3558 | 4648 | if (! pre_expr_reaches_here_p (BLOCK_NUM (avail->insn), expr, |
89e606c9 | 4649 | BLOCK_NUM (occr->insn))) |
7506f491 DE |
4650 | continue; |
4651 | ||
4652 | /* Copy the result of avail to reaching_reg. */ | |
4653 | pre_insert_copy_insn (expr, insn); | |
4654 | avail->copied_p = 1; | |
4655 | } | |
4656 | } | |
4657 | } | |
4658 | } | |
4659 | } | |
4660 | ||
4661 | /* Delete redundant computations. | |
7506f491 DE |
4662 | Deletion is done by changing the insn to copy the `reaching_reg' of |
4663 | the expression into the result of the SET. It is left to later passes | |
4664 | (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it. | |
4665 | ||
4666 | Returns non-zero if a change is made. */ | |
4667 | ||
4668 | static int | |
4669 | pre_delete () | |
4670 | { | |
a65f3558 JL |
4671 | int i, bb, changed; |
4672 | ||
4673 | /* Compute the expressions which are redundant and need to be replaced by | |
4674 | copies from the reaching reg to the target reg. */ | |
4675 | for (bb = 0; bb < n_basic_blocks; bb++) | |
a42cd965 | 4676 | sbitmap_copy (temp_bitmap[bb], pre_delete_map[bb]); |
7506f491 DE |
4677 | |
4678 | changed = 0; | |
4679 | for (i = 0; i < expr_hash_table_size; i++) | |
4680 | { | |
4681 | struct expr *expr; | |
4682 | ||
4683 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
4684 | { | |
4685 | struct occr *occr; | |
4686 | int indx = expr->bitmap_index; | |
4687 | ||
4688 | /* We only need to search antic_occr since we require | |
4689 | ANTLOC != 0. */ | |
4690 | ||
4691 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
4692 | { | |
4693 | rtx insn = occr->insn; | |
4694 | rtx set; | |
4695 | int bb = BLOCK_NUM (insn); | |
7506f491 | 4696 | |
a65f3558 | 4697 | if (TEST_BIT (temp_bitmap[bb], indx)) |
7506f491 | 4698 | { |
7506f491 DE |
4699 | set = single_set (insn); |
4700 | if (! set) | |
4701 | abort (); | |
4702 | ||
d3903c22 JL |
4703 | /* Create a pseudo-reg to store the result of reaching |
4704 | expressions into. Get the mode for the new pseudo | |
4705 | from the mode of the original destination pseudo. */ | |
4706 | if (expr->reaching_reg == NULL) | |
4707 | expr->reaching_reg | |
4708 | = gen_reg_rtx (GET_MODE (SET_DEST (set))); | |
4709 | ||
7506f491 DE |
4710 | /* In theory this should never fail since we're creating |
4711 | a reg->reg copy. | |
4712 | ||
4713 | However, on the x86 some of the movXX patterns actually | |
4714 | contain clobbers of scratch regs. This may cause the | |
db35306d | 4715 | insn created by validate_change to not match any pattern |
7506f491 DE |
4716 | and thus cause validate_change to fail. */ |
4717 | if (validate_change (insn, &SET_SRC (set), | |
4718 | expr->reaching_reg, 0)) | |
4719 | { | |
4720 | occr->deleted_p = 1; | |
a65f3558 | 4721 | SET_BIT (pre_redundant_insns, INSN_CUID (insn)); |
7506f491 DE |
4722 | changed = 1; |
4723 | gcse_subst_count++; | |
4724 | } | |
4725 | ||
4726 | if (gcse_file) | |
4727 | { | |
a65f3558 JL |
4728 | fprintf (gcse_file, |
4729 | "PRE: redundant insn %d (expression %d) in bb %d, reaching reg is %d\n", | |
7506f491 DE |
4730 | INSN_UID (insn), indx, bb, REGNO (expr->reaching_reg)); |
4731 | } | |
4732 | } | |
4733 | } | |
4734 | } | |
4735 | } | |
4736 | ||
4737 | return changed; | |
4738 | } | |
4739 | ||
4740 | /* Perform GCSE optimizations using PRE. | |
4741 | This is called by one_pre_gcse_pass after all the dataflow analysis | |
4742 | has been done. | |
4743 | ||
a65f3558 JL |
4744 | This is based on the original Morel-Renvoise paper Fred Chow's thesis, |
4745 | and lazy code motion from Knoop, Ruthing and Steffen as described in | |
4746 | Advanced Compiler Design and Implementation. | |
7506f491 DE |
4747 | |
4748 | ??? A new pseudo reg is created to hold the reaching expression. | |
4749 | The nice thing about the classical approach is that it would try to | |
4750 | use an existing reg. If the register can't be adequately optimized | |
4751 | [i.e. we introduce reload problems], one could add a pass here to | |
4752 | propagate the new register through the block. | |
4753 | ||
4754 | ??? We don't handle single sets in PARALLELs because we're [currently] | |
4755 | not able to copy the rest of the parallel when we insert copies to create | |
4756 | full redundancies from partial redundancies. However, there's no reason | |
4757 | why we can't handle PARALLELs in the cases where there are no partial | |
4758 | redundancies. */ | |
4759 | ||
4760 | static int | |
4761 | pre_gcse () | |
4762 | { | |
a42cd965 | 4763 | int i, did_insert; |
7506f491 DE |
4764 | int changed; |
4765 | struct expr **index_map; | |
4766 | ||
4767 | /* Compute a mapping from expression number (`bitmap_index') to | |
4768 | hash table entry. */ | |
4769 | ||
283a2545 | 4770 | index_map = xcalloc (n_exprs, sizeof (struct expr *)); |
7506f491 DE |
4771 | for (i = 0; i < expr_hash_table_size; i++) |
4772 | { | |
4773 | struct expr *expr; | |
4774 | ||
4775 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
4776 | index_map[expr->bitmap_index] = expr; | |
4777 | } | |
4778 | ||
4779 | /* Reset bitmap used to track which insns are redundant. */ | |
a65f3558 JL |
4780 | pre_redundant_insns = sbitmap_alloc (max_cuid); |
4781 | sbitmap_zero (pre_redundant_insns); | |
7506f491 DE |
4782 | |
4783 | /* Delete the redundant insns first so that | |
4784 | - we know what register to use for the new insns and for the other | |
4785 | ones with reaching expressions | |
4786 | - we know which insns are redundant when we go to create copies */ | |
4787 | changed = pre_delete (); | |
4788 | ||
a42cd965 | 4789 | did_insert = pre_edge_insert (edge_list, index_map); |
7506f491 | 4790 | /* In other places with reaching expressions, copy the expression to the |
a42cd965 | 4791 | specially allocated pseudo-reg that reaches the redundant expr. */ |
7506f491 | 4792 | pre_insert_copies (); |
a42cd965 AM |
4793 | if (did_insert) |
4794 | { | |
4795 | commit_edge_insertions (); | |
4796 | changed = 1; | |
4797 | } | |
7506f491 | 4798 | |
283a2545 | 4799 | free (index_map); |
a65f3558 | 4800 | free (pre_redundant_insns); |
7506f491 DE |
4801 | |
4802 | return changed; | |
4803 | } | |
4804 | ||
4805 | /* Top level routine to perform one PRE GCSE pass. | |
4806 | ||
4807 | Return non-zero if a change was made. */ | |
4808 | ||
4809 | static int | |
b5ce41ff | 4810 | one_pre_gcse_pass (pass) |
7506f491 DE |
4811 | int pass; |
4812 | { | |
4813 | int changed = 0; | |
4814 | ||
4815 | gcse_subst_count = 0; | |
4816 | gcse_create_count = 0; | |
4817 | ||
4818 | alloc_expr_hash_table (max_cuid); | |
a42cd965 | 4819 | add_noreturn_fake_exit_edges (); |
b5ce41ff | 4820 | compute_expr_hash_table (); |
7506f491 DE |
4821 | if (gcse_file) |
4822 | dump_hash_table (gcse_file, "Expression", expr_hash_table, | |
4823 | expr_hash_table_size, n_exprs); | |
4824 | if (n_exprs > 0) | |
4825 | { | |
4826 | alloc_pre_mem (n_basic_blocks, n_exprs); | |
4827 | compute_pre_data (); | |
4828 | changed |= pre_gcse (); | |
a42cd965 | 4829 | free_edge_list (edge_list); |
7506f491 DE |
4830 | free_pre_mem (); |
4831 | } | |
a42cd965 | 4832 | remove_fake_edges (); |
7506f491 DE |
4833 | free_expr_hash_table (); |
4834 | ||
4835 | if (gcse_file) | |
4836 | { | |
4837 | fprintf (gcse_file, "\n"); | |
4838 | fprintf (gcse_file, "PRE GCSE of %s, pass %d: %d bytes needed, %d substs, %d insns created\n", | |
4839 | current_function_name, pass, | |
4840 | bytes_used, gcse_subst_count, gcse_create_count); | |
4841 | } | |
4842 | ||
4843 | return changed; | |
4844 | } | |
aeb2f500 JW |
4845 | \f |
4846 | /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN. | |
4847 | We have to add REG_LABEL notes, because the following loop optimization | |
4848 | pass requires them. */ | |
4849 | ||
4850 | /* ??? This is very similar to the loop.c add_label_notes function. We | |
4851 | could probably share code here. */ | |
4852 | ||
4853 | /* ??? If there was a jump optimization pass after gcse and before loop, | |
4854 | then we would not need to do this here, because jump would add the | |
4855 | necessary REG_LABEL notes. */ | |
4856 | ||
4857 | static void | |
4858 | add_label_notes (x, insn) | |
4859 | rtx x; | |
4860 | rtx insn; | |
4861 | { | |
4862 | enum rtx_code code = GET_CODE (x); | |
4863 | int i, j; | |
6f7d635c | 4864 | const char *fmt; |
aeb2f500 JW |
4865 | |
4866 | if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x)) | |
4867 | { | |
6b3603c2 | 4868 | /* This code used to ignore labels that referred to dispatch tables to |
ac7c5af5 | 4869 | avoid flow generating (slighly) worse code. |
6b3603c2 | 4870 | |
ac7c5af5 JL |
4871 | We no longer ignore such label references (see LABEL_REF handling in |
4872 | mark_jump_label for additional information). */ | |
6b3603c2 JL |
4873 | REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, XEXP (x, 0), |
4874 | REG_NOTES (insn)); | |
aeb2f500 JW |
4875 | return; |
4876 | } | |
4877 | ||
4878 | fmt = GET_RTX_FORMAT (code); | |
4879 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
4880 | { | |
4881 | if (fmt[i] == 'e') | |
4882 | add_label_notes (XEXP (x, i), insn); | |
4883 | else if (fmt[i] == 'E') | |
4884 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
4885 | add_label_notes (XVECEXP (x, i, j), insn); | |
4886 | } | |
4887 | } | |
a65f3558 JL |
4888 | |
4889 | /* Compute transparent outgoing information for each block. | |
4890 | ||
4891 | An expression is transparent to an edge unless it is killed by | |
4892 | the edge itself. This can only happen with abnormal control flow, | |
4893 | when the edge is traversed through a call. This happens with | |
4894 | non-local labels and exceptions. | |
4895 | ||
4896 | This would not be necessary if we split the edge. While this is | |
4897 | normally impossible for abnormal critical edges, with some effort | |
4898 | it should be possible with exception handling, since we still have | |
4899 | control over which handler should be invoked. But due to increased | |
4900 | EH table sizes, this may not be worthwhile. */ | |
4901 | ||
4902 | static void | |
4903 | compute_transpout () | |
4904 | { | |
4905 | int bb; | |
4906 | ||
4907 | sbitmap_vector_ones (transpout, n_basic_blocks); | |
4908 | ||
4909 | for (bb = 0; bb < n_basic_blocks; ++bb) | |
4910 | { | |
4911 | int i; | |
4912 | ||
4913 | /* Note that flow inserted a nop a the end of basic blocks that | |
4914 | end in call instructions for reasons other than abnormal | |
4915 | control flow. */ | |
4916 | if (GET_CODE (BLOCK_END (bb)) != CALL_INSN) | |
4917 | continue; | |
4918 | ||
4919 | for (i = 0; i < expr_hash_table_size; i++) | |
4920 | { | |
4921 | struct expr *expr; | |
4922 | for (expr = expr_hash_table[i]; expr ; expr = expr->next_same_hash) | |
4923 | if (GET_CODE (expr->expr) == MEM) | |
4924 | { | |
4925 | rtx addr = XEXP (expr->expr, 0); | |
4926 | ||
4927 | if (GET_CODE (addr) == SYMBOL_REF | |
4928 | && CONSTANT_POOL_ADDRESS_P (addr)) | |
4929 | continue; | |
4930 | ||
4931 | /* ??? Optimally, we would use interprocedural alias | |
4932 | analysis to determine if this mem is actually killed | |
4933 | by this call. */ | |
4934 | RESET_BIT (transpout[bb], expr->bitmap_index); | |
4935 | } | |
4936 | } | |
4937 | } | |
4938 | } | |
dfdb644f JL |
4939 | |
4940 | /* Removal of useless null pointer checks */ | |
4941 | ||
dfdb644f | 4942 | /* Called via note_stores. X is set by SETTER. If X is a register we must |
0511851c MM |
4943 | invalidate nonnull_local and set nonnull_killed. DATA is really a |
4944 | `null_pointer_info *'. | |
dfdb644f JL |
4945 | |
4946 | We ignore hard registers. */ | |
4947 | static void | |
84832317 | 4948 | invalidate_nonnull_info (x, setter, data) |
dfdb644f JL |
4949 | rtx x; |
4950 | rtx setter ATTRIBUTE_UNUSED; | |
0511851c | 4951 | void *data; |
dfdb644f JL |
4952 | { |
4953 | int offset, regno; | |
0511851c | 4954 | struct null_pointer_info* npi = (struct null_pointer_info *) data; |
dfdb644f JL |
4955 | |
4956 | offset = 0; | |
4957 | while (GET_CODE (x) == SUBREG) | |
4958 | x = SUBREG_REG (x); | |
4959 | ||
4960 | /* Ignore anything that is not a register or is a hard register. */ | |
4961 | if (GET_CODE (x) != REG | |
0511851c MM |
4962 | || REGNO (x) < npi->min_reg |
4963 | || REGNO (x) >= npi->max_reg) | |
dfdb644f JL |
4964 | return; |
4965 | ||
0511851c | 4966 | regno = REGNO (x) - npi->min_reg; |
dfdb644f | 4967 | |
0511851c MM |
4968 | RESET_BIT (npi->nonnull_local[npi->current_block], regno); |
4969 | SET_BIT (npi->nonnull_killed[npi->current_block], regno); | |
dfdb644f JL |
4970 | } |
4971 | ||
0511851c MM |
4972 | /* Do null-pointer check elimination for the registers indicated in |
4973 | NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps; | |
4974 | they are not our responsibility to free. */ | |
dfdb644f | 4975 | |
0511851c | 4976 | static void |
b71a2ff8 | 4977 | delete_null_pointer_checks_1 (block_reg, nonnull_avin, nonnull_avout, npi) |
0511851c MM |
4978 | int *block_reg; |
4979 | sbitmap *nonnull_avin; | |
4980 | sbitmap *nonnull_avout; | |
4981 | struct null_pointer_info *npi; | |
dfdb644f | 4982 | { |
ce724250 | 4983 | int bb; |
0511851c MM |
4984 | int current_block; |
4985 | sbitmap *nonnull_local = npi->nonnull_local; | |
4986 | sbitmap *nonnull_killed = npi->nonnull_killed; | |
dfdb644f | 4987 | |
dfdb644f JL |
4988 | /* Compute local properties, nonnull and killed. A register will have |
4989 | the nonnull property if at the end of the current block its value is | |
4990 | known to be nonnull. The killed property indicates that somewhere in | |
4991 | the block any information we had about the register is killed. | |
4992 | ||
4993 | Note that a register can have both properties in a single block. That | |
4994 | indicates that it's killed, then later in the block a new value is | |
4995 | computed. */ | |
4996 | sbitmap_vector_zero (nonnull_local, n_basic_blocks); | |
4997 | sbitmap_vector_zero (nonnull_killed, n_basic_blocks); | |
4998 | for (current_block = 0; current_block < n_basic_blocks; current_block++) | |
4999 | { | |
5000 | rtx insn, stop_insn; | |
5001 | ||
0511851c MM |
5002 | /* Set the current block for invalidate_nonnull_info. */ |
5003 | npi->current_block = current_block; | |
5004 | ||
dfdb644f JL |
5005 | /* Scan each insn in the basic block looking for memory references and |
5006 | register sets. */ | |
5007 | stop_insn = NEXT_INSN (BLOCK_END (current_block)); | |
5008 | for (insn = BLOCK_HEAD (current_block); | |
5009 | insn != stop_insn; | |
5010 | insn = NEXT_INSN (insn)) | |
5011 | { | |
5012 | rtx set; | |
0511851c | 5013 | rtx reg; |
dfdb644f JL |
5014 | |
5015 | /* Ignore anything that is not a normal insn. */ | |
5016 | if (GET_RTX_CLASS (GET_CODE (insn)) != 'i') | |
5017 | continue; | |
5018 | ||
5019 | /* Basically ignore anything that is not a simple SET. We do have | |
5020 | to make sure to invalidate nonnull_local and set nonnull_killed | |
5021 | for such insns though. */ | |
5022 | set = single_set (insn); | |
5023 | if (!set) | |
5024 | { | |
0511851c | 5025 | note_stores (PATTERN (insn), invalidate_nonnull_info, npi); |
dfdb644f JL |
5026 | continue; |
5027 | } | |
5028 | ||
5029 | /* See if we've got a useable memory load. We handle it first | |
5030 | in case it uses its address register as a dest (which kills | |
5031 | the nonnull property). */ | |
5032 | if (GET_CODE (SET_SRC (set)) == MEM | |
0511851c MM |
5033 | && GET_CODE ((reg = XEXP (SET_SRC (set), 0))) == REG |
5034 | && REGNO (reg) >= npi->min_reg | |
5035 | && REGNO (reg) < npi->max_reg) | |
dfdb644f | 5036 | SET_BIT (nonnull_local[current_block], |
0511851c | 5037 | REGNO (reg) - npi->min_reg); |
dfdb644f JL |
5038 | |
5039 | /* Now invalidate stuff clobbered by this insn. */ | |
0511851c | 5040 | note_stores (PATTERN (insn), invalidate_nonnull_info, npi); |
dfdb644f JL |
5041 | |
5042 | /* And handle stores, we do these last since any sets in INSN can | |
5043 | not kill the nonnull property if it is derived from a MEM | |
5044 | appearing in a SET_DEST. */ | |
5045 | if (GET_CODE (SET_DEST (set)) == MEM | |
0511851c MM |
5046 | && GET_CODE ((reg = XEXP (SET_DEST (set), 0))) == REG |
5047 | && REGNO (reg) >= npi->min_reg | |
5048 | && REGNO (reg) < npi->max_reg) | |
dfdb644f | 5049 | SET_BIT (nonnull_local[current_block], |
0511851c | 5050 | REGNO (reg) - npi->min_reg); |
dfdb644f JL |
5051 | } |
5052 | } | |
5053 | ||
5054 | /* Now compute global properties based on the local properties. This | |
5055 | is a classic global availablity algorithm. */ | |
ce724250 JL |
5056 | compute_available (nonnull_local, nonnull_killed, |
5057 | nonnull_avout, nonnull_avin); | |
dfdb644f JL |
5058 | |
5059 | /* Now look at each bb and see if it ends with a compare of a value | |
5060 | against zero. */ | |
5061 | for (bb = 0; bb < n_basic_blocks; bb++) | |
5062 | { | |
5063 | rtx last_insn = BLOCK_END (bb); | |
0511851c | 5064 | rtx condition, earliest; |
dfdb644f JL |
5065 | int compare_and_branch; |
5066 | ||
0511851c MM |
5067 | /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and |
5068 | since BLOCK_REG[BB] is zero if this block did not end with a | |
5069 | comparison against zero, this condition works. */ | |
5070 | if (block_reg[bb] < npi->min_reg | |
5071 | || block_reg[bb] >= npi->max_reg) | |
dfdb644f JL |
5072 | continue; |
5073 | ||
5074 | /* LAST_INSN is a conditional jump. Get its condition. */ | |
5075 | condition = get_condition (last_insn, &earliest); | |
5076 | ||
dfdb644f | 5077 | /* Is the register known to have a nonzero value? */ |
0511851c | 5078 | if (!TEST_BIT (nonnull_avout[bb], block_reg[bb] - npi->min_reg)) |
dfdb644f JL |
5079 | continue; |
5080 | ||
5081 | /* Try to compute whether the compare/branch at the loop end is one or | |
5082 | two instructions. */ | |
5083 | if (earliest == last_insn) | |
5084 | compare_and_branch = 1; | |
5085 | else if (earliest == prev_nonnote_insn (last_insn)) | |
5086 | compare_and_branch = 2; | |
5087 | else | |
5088 | continue; | |
5089 | ||
5090 | /* We know the register in this comparison is nonnull at exit from | |
5091 | this block. We can optimize this comparison. */ | |
5092 | if (GET_CODE (condition) == NE) | |
5093 | { | |
5094 | rtx new_jump; | |
5095 | ||
5096 | new_jump = emit_jump_insn_before (gen_jump (JUMP_LABEL (last_insn)), | |
5097 | last_insn); | |
5098 | JUMP_LABEL (new_jump) = JUMP_LABEL (last_insn); | |
5099 | LABEL_NUSES (JUMP_LABEL (new_jump))++; | |
5100 | emit_barrier_after (new_jump); | |
5101 | } | |
5102 | delete_insn (last_insn); | |
5103 | if (compare_and_branch == 2) | |
5104 | delete_insn (earliest); | |
0511851c MM |
5105 | |
5106 | /* Don't check this block again. (Note that BLOCK_END is | |
5107 | invalid here; we deleted the last instruction in the | |
5108 | block.) */ | |
5109 | block_reg[bb] = 0; | |
5110 | } | |
5111 | } | |
5112 | ||
5113 | /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated | |
5114 | at compile time. | |
5115 | ||
5116 | This is conceptually similar to global constant/copy propagation and | |
5117 | classic global CSE (it even uses the same dataflow equations as cprop). | |
5118 | ||
5119 | If a register is used as memory address with the form (mem (reg)), then we | |
5120 | know that REG can not be zero at that point in the program. Any instruction | |
5121 | which sets REG "kills" this property. | |
5122 | ||
5123 | So, if every path leading to a conditional branch has an available memory | |
5124 | reference of that form, then we know the register can not have the value | |
5125 | zero at the conditional branch. | |
5126 | ||
5127 | So we merely need to compute the local properies and propagate that data | |
5128 | around the cfg, then optimize where possible. | |
5129 | ||
5130 | We run this pass two times. Once before CSE, then again after CSE. This | |
5131 | has proven to be the most profitable approach. It is rare for new | |
5132 | optimization opportunities of this nature to appear after the first CSE | |
5133 | pass. | |
5134 | ||
5135 | This could probably be integrated with global cprop with a little work. */ | |
5136 | ||
5137 | void | |
5138 | delete_null_pointer_checks (f) | |
5139 | rtx f; | |
5140 | { | |
0511851c MM |
5141 | sbitmap *nonnull_avin, *nonnull_avout; |
5142 | int *block_reg; | |
5143 | int bb; | |
5144 | int reg; | |
5145 | int regs_per_pass; | |
5146 | int max_reg; | |
5147 | struct null_pointer_info npi; | |
5148 | ||
5149 | /* First break the program into basic blocks. */ | |
5150 | find_basic_blocks (f, max_reg_num (), NULL, 1); | |
5151 | ||
5152 | /* If we have only a single block, then there's nothing to do. */ | |
5153 | if (n_basic_blocks <= 1) | |
5154 | { | |
5155 | /* Free storage allocated by find_basic_blocks. */ | |
5156 | free_basic_block_vars (0); | |
5157 | return; | |
5158 | } | |
5159 | ||
5160 | /* Trying to perform global optimizations on flow graphs which have | |
5161 | a high connectivity will take a long time and is unlikely to be | |
5162 | particularly useful. | |
5163 | ||
5164 | In normal circumstances a cfg should have about twice has many edges | |
5165 | as blocks. But we do not want to punish small functions which have | |
5166 | a couple switch statements. So we require a relatively large number | |
5167 | of basic blocks and the ratio of edges to blocks to be high. */ | |
5168 | if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20) | |
5169 | { | |
5170 | /* Free storage allocated by find_basic_blocks. */ | |
5171 | free_basic_block_vars (0); | |
5172 | return; | |
5173 | } | |
5174 | ||
0511851c MM |
5175 | /* We need four bitmaps, each with a bit for each register in each |
5176 | basic block. */ | |
5177 | max_reg = max_reg_num (); | |
5178 | regs_per_pass = get_bitmap_width (4, n_basic_blocks, max_reg); | |
5179 | ||
5180 | /* Allocate bitmaps to hold local and global properties. */ | |
5181 | npi.nonnull_local = sbitmap_vector_alloc (n_basic_blocks, regs_per_pass); | |
5182 | npi.nonnull_killed = sbitmap_vector_alloc (n_basic_blocks, regs_per_pass); | |
5183 | nonnull_avin = sbitmap_vector_alloc (n_basic_blocks, regs_per_pass); | |
5184 | nonnull_avout = sbitmap_vector_alloc (n_basic_blocks, regs_per_pass); | |
5185 | ||
5186 | /* Go through the basic blocks, seeing whether or not each block | |
5187 | ends with a conditional branch whose condition is a comparison | |
5188 | against zero. Record the register compared in BLOCK_REG. */ | |
5189 | block_reg = (int *) xcalloc (n_basic_blocks, sizeof (int)); | |
5190 | for (bb = 0; bb < n_basic_blocks; bb++) | |
5191 | { | |
5192 | rtx last_insn = BLOCK_END (bb); | |
5193 | rtx condition, earliest, reg; | |
5194 | ||
5195 | /* We only want conditional branches. */ | |
5196 | if (GET_CODE (last_insn) != JUMP_INSN | |
5197 | || !condjump_p (last_insn) | |
5198 | || simplejump_p (last_insn)) | |
5199 | continue; | |
5200 | ||
5201 | /* LAST_INSN is a conditional jump. Get its condition. */ | |
5202 | condition = get_condition (last_insn, &earliest); | |
5203 | ||
5204 | /* If we were unable to get the condition, or it is not a equality | |
5205 | comparison against zero then there's nothing we can do. */ | |
5206 | if (!condition | |
5207 | || (GET_CODE (condition) != NE && GET_CODE (condition) != EQ) | |
5208 | || GET_CODE (XEXP (condition, 1)) != CONST_INT | |
5209 | || (XEXP (condition, 1) | |
5210 | != CONST0_RTX (GET_MODE (XEXP (condition, 0))))) | |
5211 | continue; | |
5212 | ||
5213 | /* We must be checking a register against zero. */ | |
5214 | reg = XEXP (condition, 0); | |
5215 | if (GET_CODE (reg) != REG) | |
5216 | continue; | |
5217 | ||
5218 | block_reg[bb] = REGNO (reg); | |
5219 | } | |
5220 | ||
5221 | /* Go through the algorithm for each block of registers. */ | |
5222 | for (reg = FIRST_PSEUDO_REGISTER; reg < max_reg; reg += regs_per_pass) | |
5223 | { | |
5224 | npi.min_reg = reg; | |
5225 | npi.max_reg = MIN (reg + regs_per_pass, max_reg); | |
b71a2ff8 | 5226 | delete_null_pointer_checks_1 (block_reg, nonnull_avin, |
0511851c | 5227 | nonnull_avout, &npi); |
dfdb644f JL |
5228 | } |
5229 | ||
5230 | /* Free storage allocated by find_basic_blocks. */ | |
5231 | free_basic_block_vars (0); | |
5232 | ||
0511851c MM |
5233 | /* Free the table of registers compared at the end of every block. */ |
5234 | free (block_reg); | |
5235 | ||
dfdb644f | 5236 | /* Free bitmaps. */ |
0511851c MM |
5237 | free (npi.nonnull_local); |
5238 | free (npi.nonnull_killed); | |
dfdb644f JL |
5239 | free (nonnull_avin); |
5240 | free (nonnull_avout); | |
5241 | } | |
bb457bd9 JL |
5242 | |
5243 | /* Code Hoisting variables and subroutines. */ | |
5244 | ||
5245 | /* Very busy expressions. */ | |
5246 | static sbitmap *hoist_vbein; | |
5247 | static sbitmap *hoist_vbeout; | |
5248 | ||
5249 | /* Hoistable expressions. */ | |
5250 | static sbitmap *hoist_exprs; | |
5251 | ||
5252 | /* Dominator bitmaps. */ | |
5253 | static sbitmap *dominators; | |
bb457bd9 JL |
5254 | |
5255 | /* ??? We could compute post dominators and run this algorithm in | |
5256 | reverse to to perform tail merging, doing so would probably be | |
5257 | more effective than the tail merging code in jump.c. | |
5258 | ||
5259 | It's unclear if tail merging could be run in parallel with | |
5260 | code hoisting. It would be nice. */ | |
5261 | ||
5262 | /* Allocate vars used for code hoisting analysis. */ | |
5263 | ||
5264 | static void | |
5265 | alloc_code_hoist_mem (n_blocks, n_exprs) | |
5266 | int n_blocks, n_exprs; | |
5267 | { | |
5268 | antloc = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5269 | transp = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5270 | comp = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5271 | ||
5272 | hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5273 | hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5274 | hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5275 | transpout = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5276 | ||
5277 | dominators = sbitmap_vector_alloc (n_blocks, n_blocks); | |
bb457bd9 JL |
5278 | } |
5279 | ||
5280 | /* Free vars used for code hoisting analysis. */ | |
5281 | ||
5282 | static void | |
5283 | free_code_hoist_mem () | |
5284 | { | |
5285 | free (antloc); | |
5286 | free (transp); | |
5287 | free (comp); | |
5288 | ||
5289 | free (hoist_vbein); | |
5290 | free (hoist_vbeout); | |
5291 | free (hoist_exprs); | |
5292 | free (transpout); | |
5293 | ||
5294 | free (dominators); | |
bb457bd9 JL |
5295 | } |
5296 | ||
5297 | /* Compute the very busy expressions at entry/exit from each block. | |
5298 | ||
5299 | An expression is very busy if all paths from a given point | |
5300 | compute the expression. */ | |
5301 | ||
5302 | static void | |
5303 | compute_code_hoist_vbeinout () | |
5304 | { | |
5305 | int bb, changed, passes; | |
5306 | ||
5307 | sbitmap_vector_zero (hoist_vbeout, n_basic_blocks); | |
5308 | sbitmap_vector_zero (hoist_vbein, n_basic_blocks); | |
5309 | ||
5310 | passes = 0; | |
5311 | changed = 1; | |
5312 | while (changed) | |
5313 | { | |
5314 | changed = 0; | |
5315 | /* We scan the blocks in the reverse order to speed up | |
5316 | the convergence. */ | |
5317 | for (bb = n_basic_blocks - 1; bb >= 0; bb--) | |
5318 | { | |
5319 | changed |= sbitmap_a_or_b_and_c (hoist_vbein[bb], antloc[bb], | |
5320 | hoist_vbeout[bb], transp[bb]); | |
5321 | if (bb != n_basic_blocks - 1) | |
a42cd965 | 5322 | sbitmap_intersection_of_succs (hoist_vbeout[bb], hoist_vbein, bb); |
bb457bd9 JL |
5323 | } |
5324 | passes++; | |
5325 | } | |
5326 | ||
5327 | if (gcse_file) | |
5328 | fprintf (gcse_file, "hoisting vbeinout computation: %d passes\n", passes); | |
5329 | } | |
5330 | ||
5331 | /* Top level routine to do the dataflow analysis needed by code hoisting. */ | |
5332 | ||
5333 | static void | |
5334 | compute_code_hoist_data () | |
5335 | { | |
5336 | compute_local_properties (transp, comp, antloc, 0); | |
5337 | compute_transpout (); | |
5338 | compute_code_hoist_vbeinout (); | |
092ae4ba | 5339 | compute_flow_dominators (dominators, NULL); |
bb457bd9 JL |
5340 | if (gcse_file) |
5341 | fprintf (gcse_file, "\n"); | |
5342 | } | |
5343 | ||
5344 | /* Determine if the expression identified by EXPR_INDEX would | |
5345 | reach BB unimpared if it was placed at the end of EXPR_BB. | |
5346 | ||
5347 | It's unclear exactly what Muchnick meant by "unimpared". It seems | |
5348 | to me that the expression must either be computed or transparent in | |
5349 | *every* block in the path(s) from EXPR_BB to BB. Any other definition | |
5350 | would allow the expression to be hoisted out of loops, even if | |
5351 | the expression wasn't a loop invariant. | |
5352 | ||
5353 | Contrast this to reachability for PRE where an expression is | |
5354 | considered reachable if *any* path reaches instead of *all* | |
5355 | paths. */ | |
5356 | ||
5357 | static int | |
5358 | hoist_expr_reaches_here_p (expr_bb, expr_index, bb, visited) | |
5359 | int expr_bb; | |
5360 | int expr_index; | |
5361 | int bb; | |
5362 | char *visited; | |
5363 | { | |
5364 | edge pred; | |
283a2545 RL |
5365 | int visited_allocated_locally = 0; |
5366 | ||
bb457bd9 JL |
5367 | |
5368 | if (visited == NULL) | |
5369 | { | |
283a2545 RL |
5370 | visited_allocated_locally = 1; |
5371 | visited = xcalloc (n_basic_blocks, 1); | |
bb457bd9 JL |
5372 | } |
5373 | ||
5374 | visited[expr_bb] = 1; | |
5375 | for (pred = BASIC_BLOCK (bb)->pred; pred != NULL; pred = pred->pred_next) | |
5376 | { | |
5377 | int pred_bb = pred->src->index; | |
5378 | ||
5379 | if (pred->src == ENTRY_BLOCK_PTR) | |
5380 | break; | |
5381 | else if (visited[pred_bb]) | |
5382 | continue; | |
5383 | /* Does this predecessor generate this expression? */ | |
5384 | else if (TEST_BIT (comp[pred_bb], expr_index)) | |
5385 | break; | |
5386 | else if (! TEST_BIT (transp[pred_bb], expr_index)) | |
5387 | break; | |
5388 | /* Not killed. */ | |
5389 | else | |
5390 | { | |
5391 | visited[pred_bb] = 1; | |
5392 | if (! hoist_expr_reaches_here_p (expr_bb, expr_index, | |
5393 | pred_bb, visited)) | |
5394 | break; | |
5395 | } | |
5396 | } | |
283a2545 RL |
5397 | if (visited_allocated_locally) |
5398 | free (visited); | |
bb457bd9 JL |
5399 | return (pred == NULL); |
5400 | } | |
5401 | \f | |
5402 | /* Actually perform code hoisting. */ | |
5403 | static void | |
5404 | hoist_code () | |
5405 | { | |
5406 | int bb, dominated, i; | |
5407 | struct expr **index_map; | |
5408 | ||
5409 | sbitmap_vector_zero (hoist_exprs, n_basic_blocks); | |
5410 | ||
5411 | /* Compute a mapping from expression number (`bitmap_index') to | |
5412 | hash table entry. */ | |
5413 | ||
283a2545 | 5414 | index_map = xcalloc (n_exprs, sizeof (struct expr *)); |
bb457bd9 JL |
5415 | for (i = 0; i < expr_hash_table_size; i++) |
5416 | { | |
5417 | struct expr *expr; | |
5418 | ||
5419 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
5420 | index_map[expr->bitmap_index] = expr; | |
5421 | } | |
5422 | ||
5423 | /* Walk over each basic block looking for potentially hoistable | |
5424 | expressions, nothing gets hoisted from the entry block. */ | |
5425 | for (bb = 0; bb < n_basic_blocks; bb++) | |
5426 | { | |
5427 | int found = 0; | |
5428 | int insn_inserted_p; | |
5429 | ||
5430 | /* Examine each expression that is very busy at the exit of this | |
5431 | block. These are the potentially hoistable expressions. */ | |
5432 | for (i = 0; i < hoist_vbeout[bb]->n_bits; i++) | |
5433 | { | |
5434 | int hoistable = 0; | |
5435 | if (TEST_BIT (hoist_vbeout[bb], i) | |
5436 | && TEST_BIT (transpout[bb], i)) | |
5437 | { | |
5438 | /* We've found a potentially hoistable expression, now | |
5439 | we look at every block BB dominates to see if it | |
5440 | computes the expression. */ | |
5441 | for (dominated = 0; dominated < n_basic_blocks; dominated++) | |
5442 | { | |
5443 | /* Ignore self dominance. */ | |
5444 | if (bb == dominated | |
5445 | || ! TEST_BIT (dominators[dominated], bb)) | |
5446 | continue; | |
5447 | ||
5448 | /* We've found a dominated block, now see if it computes | |
5449 | the busy expression and whether or not moving that | |
5450 | expression to the "beginning" of that block is safe. */ | |
5451 | if (!TEST_BIT (antloc[dominated], i)) | |
5452 | continue; | |
5453 | ||
5454 | /* Note if the expression would reach the dominated block | |
5455 | unimpared if it was placed at the end of BB. | |
5456 | ||
5457 | Keep track of how many times this expression is hoistable | |
5458 | from a dominated block into BB. */ | |
5459 | if (hoist_expr_reaches_here_p (bb, i, dominated, NULL)) | |
5460 | hoistable++; | |
5461 | } | |
5462 | ||
5463 | /* If we found more than one hoistable occurence of this | |
5464 | expression, then note it in the bitmap of expressions to | |
5465 | hoist. It makes no sense to hoist things which are computed | |
5466 | in only one BB, and doing so tends to pessimize register | |
5467 | allocation. One could increase this value to try harder | |
5468 | to avoid any possible code expansion due to register | |
5469 | allocation issues; however experiments have shown that | |
5470 | the vast majority of hoistable expressions are only movable | |
5471 | from two successors, so raising this threshhold is likely | |
5472 | to nullify any benefit we get from code hoisting. */ | |
5473 | if (hoistable > 1) | |
5474 | { | |
5475 | SET_BIT (hoist_exprs[bb], i); | |
5476 | found = 1; | |
5477 | } | |
5478 | } | |
5479 | } | |
5480 | ||
5481 | /* If we found nothing to hoist, then quit now. */ | |
5482 | if (! found) | |
5483 | continue; | |
5484 | ||
5485 | /* Loop over all the hoistable expressions. */ | |
5486 | for (i = 0; i < hoist_exprs[bb]->n_bits; i++) | |
5487 | { | |
5488 | /* We want to insert the expression into BB only once, so | |
5489 | note when we've inserted it. */ | |
5490 | insn_inserted_p = 0; | |
5491 | ||
5492 | /* These tests should be the same as the tests above. */ | |
5493 | if (TEST_BIT (hoist_vbeout[bb], i)) | |
5494 | { | |
5495 | /* We've found a potentially hoistable expression, now | |
5496 | we look at every block BB dominates to see if it | |
5497 | computes the expression. */ | |
5498 | for (dominated = 0; dominated < n_basic_blocks; dominated++) | |
5499 | { | |
5500 | /* Ignore self dominance. */ | |
5501 | if (bb == dominated | |
5502 | || ! TEST_BIT (dominators[dominated], bb)) | |
5503 | continue; | |
5504 | ||
5505 | /* We've found a dominated block, now see if it computes | |
5506 | the busy expression and whether or not moving that | |
5507 | expression to the "beginning" of that block is safe. */ | |
5508 | if (!TEST_BIT (antloc[dominated], i)) | |
5509 | continue; | |
5510 | ||
5511 | /* The expression is computed in the dominated block and | |
5512 | it would be safe to compute it at the start of the | |
5513 | dominated block. Now we have to determine if the | |
5514 | expresion would reach the dominated block if it was | |
5515 | placed at the end of BB. */ | |
5516 | if (hoist_expr_reaches_here_p (bb, i, dominated, NULL)) | |
5517 | { | |
5518 | struct expr *expr = index_map[i]; | |
5519 | struct occr *occr = expr->antic_occr; | |
5520 | rtx insn; | |
5521 | rtx set; | |
5522 | ||
5523 | ||
5524 | /* Find the right occurence of this expression. */ | |
5525 | while (BLOCK_NUM (occr->insn) != dominated && occr) | |
5526 | occr = occr->next; | |
5527 | ||
5528 | /* Should never happen. */ | |
5529 | if (!occr) | |
5530 | abort (); | |
5531 | ||
5532 | insn = occr->insn; | |
5533 | ||
5534 | set = single_set (insn); | |
5535 | if (! set) | |
5536 | abort (); | |
5537 | ||
5538 | /* Create a pseudo-reg to store the result of reaching | |
5539 | expressions into. Get the mode for the new pseudo | |
5540 | from the mode of the original destination pseudo. */ | |
5541 | if (expr->reaching_reg == NULL) | |
5542 | expr->reaching_reg | |
5543 | = gen_reg_rtx (GET_MODE (SET_DEST (set))); | |
5544 | ||
5545 | /* In theory this should never fail since we're creating | |
5546 | a reg->reg copy. | |
5547 | ||
5548 | However, on the x86 some of the movXX patterns actually | |
5549 | contain clobbers of scratch regs. This may cause the | |
5550 | insn created by validate_change to not match any | |
5551 | pattern and thus cause validate_change to fail. */ | |
5552 | if (validate_change (insn, &SET_SRC (set), | |
5553 | expr->reaching_reg, 0)) | |
5554 | { | |
5555 | occr->deleted_p = 1; | |
5556 | if (!insn_inserted_p) | |
5557 | { | |
5558 | insert_insn_end_bb (index_map[i], bb, 0); | |
5559 | insn_inserted_p = 1; | |
5560 | } | |
5561 | } | |
5562 | } | |
5563 | } | |
5564 | } | |
5565 | } | |
5566 | } | |
283a2545 | 5567 | free (index_map); |
bb457bd9 JL |
5568 | } |
5569 | ||
5570 | /* Top level routine to perform one code hoisting (aka unification) pass | |
5571 | ||
5572 | Return non-zero if a change was made. */ | |
5573 | ||
5574 | static int | |
5575 | one_code_hoisting_pass () | |
5576 | { | |
5577 | int changed = 0; | |
5578 | ||
5579 | alloc_expr_hash_table (max_cuid); | |
5580 | compute_expr_hash_table (); | |
5581 | if (gcse_file) | |
5582 | dump_hash_table (gcse_file, "Code Hosting Expressions", expr_hash_table, | |
5583 | expr_hash_table_size, n_exprs); | |
5584 | if (n_exprs > 0) | |
5585 | { | |
5586 | alloc_code_hoist_mem (n_basic_blocks, n_exprs); | |
5587 | compute_code_hoist_data (); | |
5588 | hoist_code (); | |
5589 | free_code_hoist_mem (); | |
5590 | } | |
5591 | free_expr_hash_table (); | |
5592 | ||
5593 | return changed; | |
5594 | } |