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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 | ||
129 | People wishing to speed up the code here should read: | |
130 | Elimination Algorithms for Data Flow Analysis | |
131 | B.G. Ryder, M.C. Paull | |
132 | ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986 | |
133 | ||
134 | How to Analyze Large Programs Efficiently and Informatively | |
135 | D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck | |
136 | ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI | |
137 | ||
7506f491 DE |
138 | People wishing to do something different can find various possibilities |
139 | in the above papers and elsewhere. | |
140 | */ | |
141 | ||
142 | #include "config.h" | |
50b2596f | 143 | #include "system.h" |
7506f491 DE |
144 | |
145 | #include "rtl.h" | |
146 | #include "regs.h" | |
147 | #include "hard-reg-set.h" | |
148 | #include "flags.h" | |
149 | #include "real.h" | |
150 | #include "insn-config.h" | |
151 | #include "recog.h" | |
152 | #include "basic-block.h" | |
50b2596f | 153 | #include "output.h" |
3cdbd1f8 | 154 | #include "expr.h" |
7506f491 DE |
155 | |
156 | #include "obstack.h" | |
157 | #define obstack_chunk_alloc gmalloc | |
158 | #define obstack_chunk_free free | |
159 | ||
160 | /* Maximum number of passes to perform. */ | |
161 | #define MAX_PASSES 1 | |
162 | ||
163 | /* Propagate flow information through back edges and thus enable PRE's | |
164 | moving loop invariant calculations out of loops. | |
165 | ||
166 | Originally this tended to create worse overall code, but several | |
167 | improvements during the development of PRE seem to have made following | |
168 | back edges generally a win. | |
169 | ||
170 | Note much of the loop invariant code motion done here would normally | |
171 | be done by loop.c, which has more heuristics for when to move invariants | |
172 | out of loops. At some point we might need to move some of those | |
173 | heuristics into gcse.c. */ | |
174 | #define FOLLOW_BACK_EDGES 1 | |
175 | ||
f4e584dc JL |
176 | /* We support GCSE via Partial Redundancy Elimination. PRE optimizations |
177 | are a superset of those done by GCSE. | |
7506f491 | 178 | |
f4e584dc | 179 | We perform the following steps: |
7506f491 DE |
180 | |
181 | 1) Compute basic block information. | |
182 | ||
183 | 2) Compute table of places where registers are set. | |
184 | ||
185 | 3) Perform copy/constant propagation. | |
186 | ||
187 | 4) Perform global cse. | |
188 | ||
e78d9500 | 189 | 5) Perform another pass of copy/constant propagation. |
7506f491 DE |
190 | |
191 | Two passes of copy/constant propagation are done because the first one | |
192 | enables more GCSE and the second one helps to clean up the copies that | |
193 | GCSE creates. This is needed more for PRE than for Classic because Classic | |
194 | GCSE will try to use an existing register containing the common | |
195 | subexpression rather than create a new one. This is harder to do for PRE | |
196 | because of the code motion (which Classic GCSE doesn't do). | |
197 | ||
198 | Expressions we are interested in GCSE-ing are of the form | |
199 | (set (pseudo-reg) (expression)). | |
200 | Function want_to_gcse_p says what these are. | |
201 | ||
202 | PRE handles moving invariant expressions out of loops (by treating them as | |
f4e584dc | 203 | partially redundant). |
7506f491 DE |
204 | |
205 | Eventually it would be nice to replace cse.c/gcse.c with SSA (static single | |
206 | assignment) based GVN (global value numbering). L. T. Simpson's paper | |
207 | (Rice University) on value numbering is a useful reference for this. | |
208 | ||
209 | ********************** | |
210 | ||
211 | We used to support multiple passes but there are diminishing returns in | |
212 | doing so. The first pass usually makes 90% of the changes that are doable. | |
213 | A second pass can make a few more changes made possible by the first pass. | |
214 | Experiments show any further passes don't make enough changes to justify | |
215 | the expense. | |
216 | ||
217 | A study of spec92 using an unlimited number of passes: | |
218 | [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83, | |
219 | [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2, | |
220 | [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1 | |
221 | ||
222 | It was found doing copy propagation between each pass enables further | |
223 | substitutions. | |
224 | ||
225 | PRE is quite expensive in complicated functions because the DFA can take | |
226 | awhile to converge. Hence we only perform one pass. Macro MAX_PASSES can | |
227 | be modified if one wants to experiment. | |
228 | ||
229 | ********************** | |
230 | ||
231 | The steps for PRE are: | |
232 | ||
233 | 1) Build the hash table of expressions we wish to GCSE (expr_hash_table). | |
234 | ||
235 | 2) Perform the data flow analysis for PRE. | |
236 | ||
237 | 3) Delete the redundant instructions | |
238 | ||
239 | 4) Insert the required copies [if any] that make the partially | |
240 | redundant instructions fully redundant. | |
241 | ||
242 | 5) For other reaching expressions, insert an instruction to copy the value | |
243 | to a newly created pseudo that will reach the redundant instruction. | |
244 | ||
245 | The deletion is done first so that when we do insertions we | |
246 | know which pseudo reg to use. | |
247 | ||
248 | Various papers have argued that PRE DFA is expensive (O(n^2)) and others | |
249 | argue it is not. The number of iterations for the algorithm to converge | |
250 | is typically 2-4 so I don't view it as that expensive (relatively speaking). | |
251 | ||
f4e584dc | 252 | PRE GCSE depends heavily on the second CSE pass to clean up the copies |
7506f491 DE |
253 | we create. To make an expression reach the place where it's redundant, |
254 | the result of the expression is copied to a new register, and the redundant | |
255 | expression is deleted by replacing it with this new register. Classic GCSE | |
256 | doesn't have this problem as much as it computes the reaching defs of | |
257 | each register in each block and thus can try to use an existing register. | |
258 | ||
259 | ********************** | |
260 | ||
7506f491 DE |
261 | A fair bit of simplicity is created by creating small functions for simple |
262 | tasks, even when the function is only called in one place. This may | |
263 | measurably slow things down [or may not] by creating more function call | |
264 | overhead than is necessary. The source is laid out so that it's trivial | |
265 | to make the affected functions inline so that one can measure what speed | |
266 | up, if any, can be achieved, and maybe later when things settle things can | |
267 | be rearranged. | |
268 | ||
269 | Help stamp out big monolithic functions! */ | |
270 | \f | |
271 | /* GCSE global vars. */ | |
272 | ||
273 | /* -dG dump file. */ | |
274 | static FILE *gcse_file; | |
275 | ||
f4e584dc JL |
276 | /* Note whether or not we should run jump optimization after gcse. We |
277 | want to do this for two cases. | |
278 | ||
279 | * If we changed any jumps via cprop. | |
280 | ||
281 | * If we added any labels via edge splitting. */ | |
282 | ||
283 | static int run_jump_opt_after_gcse; | |
284 | ||
285 | /* Element I is a list of I's predecessors/successors. */ | |
286 | static int_list_ptr *s_preds; | |
287 | static int_list_ptr *s_succs; | |
288 | ||
289 | /* Element I is the number of predecessors/successors of basic block I. */ | |
290 | static int *num_preds; | |
291 | static int *num_succs; | |
292 | ||
7506f491 DE |
293 | /* Bitmaps are normally not included in debugging dumps. |
294 | However it's useful to be able to print them from GDB. | |
295 | We could create special functions for this, but it's simpler to | |
296 | just allow passing stderr to the dump_foo fns. Since stderr can | |
297 | be a macro, we store a copy here. */ | |
298 | static FILE *debug_stderr; | |
299 | ||
300 | /* An obstack for our working variables. */ | |
301 | static struct obstack gcse_obstack; | |
302 | ||
303 | /* Non-zero for each mode that supports (set (reg) (reg)). | |
304 | This is trivially true for integer and floating point values. | |
305 | It may or may not be true for condition codes. */ | |
306 | static char can_copy_p[(int) NUM_MACHINE_MODES]; | |
307 | ||
308 | /* Non-zero if can_copy_p has been initialized. */ | |
309 | static int can_copy_init_p; | |
310 | ||
7506f491 DE |
311 | /* Hash table of expressions. */ |
312 | ||
313 | struct expr | |
314 | { | |
315 | /* The expression (SET_SRC for expressions, PATTERN for assignments). */ | |
316 | rtx expr; | |
317 | /* Index in the available expression bitmaps. */ | |
318 | int bitmap_index; | |
319 | /* Next entry with the same hash. */ | |
320 | struct expr *next_same_hash; | |
321 | /* List of anticipatable occurrences in basic blocks in the function. | |
322 | An "anticipatable occurrence" is one that is the first occurrence in the | |
f4e584dc JL |
323 | basic block, the operands are not modified in the basic block prior |
324 | to the occurrence and the output is not used between the start of | |
325 | the block and the occurrence. */ | |
7506f491 DE |
326 | struct occr *antic_occr; |
327 | /* List of available occurrence in basic blocks in the function. | |
328 | An "available occurrence" is one that is the last occurrence in the | |
329 | basic block and the operands are not modified by following statements in | |
330 | the basic block [including this insn]. */ | |
331 | struct occr *avail_occr; | |
332 | /* Non-null if the computation is PRE redundant. | |
333 | The value is the newly created pseudo-reg to record a copy of the | |
334 | expression in all the places that reach the redundant copy. */ | |
335 | rtx reaching_reg; | |
336 | }; | |
337 | ||
338 | /* Occurrence of an expression. | |
339 | There is one per basic block. If a pattern appears more than once the | |
340 | last appearance is used [or first for anticipatable expressions]. */ | |
341 | ||
342 | struct occr | |
343 | { | |
344 | /* Next occurrence of this expression. */ | |
345 | struct occr *next; | |
346 | /* The insn that computes the expression. */ | |
347 | rtx insn; | |
348 | /* Non-zero if this [anticipatable] occurrence has been deleted. */ | |
349 | char deleted_p; | |
350 | /* Non-zero if this [available] occurrence has been copied to | |
351 | reaching_reg. */ | |
352 | /* ??? This is mutually exclusive with deleted_p, so they could share | |
353 | the same byte. */ | |
354 | char copied_p; | |
355 | }; | |
356 | ||
357 | /* Expression and copy propagation hash tables. | |
358 | Each hash table is an array of buckets. | |
359 | ??? It is known that if it were an array of entries, structure elements | |
360 | `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is | |
361 | not clear whether in the final analysis a sufficient amount of memory would | |
362 | be saved as the size of the available expression bitmaps would be larger | |
363 | [one could build a mapping table without holes afterwards though]. | |
364 | Someday I'll perform the computation and figure it out. | |
365 | */ | |
366 | ||
367 | /* Total size of the expression hash table, in elements. */ | |
368 | static int expr_hash_table_size; | |
369 | /* The table itself. | |
370 | This is an array of `expr_hash_table_size' elements. */ | |
371 | static struct expr **expr_hash_table; | |
372 | ||
373 | /* Total size of the copy propagation hash table, in elements. */ | |
374 | static int set_hash_table_size; | |
375 | /* The table itself. | |
376 | This is an array of `set_hash_table_size' elements. */ | |
377 | static struct expr **set_hash_table; | |
378 | ||
379 | /* Mapping of uids to cuids. | |
380 | Only real insns get cuids. */ | |
381 | static int *uid_cuid; | |
382 | ||
383 | /* Highest UID in UID_CUID. */ | |
384 | static int max_uid; | |
385 | ||
386 | /* Get the cuid of an insn. */ | |
387 | #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)]) | |
388 | ||
389 | /* Number of cuids. */ | |
390 | static int max_cuid; | |
391 | ||
392 | /* Mapping of cuids to insns. */ | |
393 | static rtx *cuid_insn; | |
394 | ||
395 | /* Get insn from cuid. */ | |
396 | #define CUID_INSN(CUID) (cuid_insn[CUID]) | |
397 | ||
398 | /* Maximum register number in function prior to doing gcse + 1. | |
399 | Registers created during this pass have regno >= max_gcse_regno. | |
400 | This is named with "gcse" to not collide with global of same name. */ | |
401 | static int max_gcse_regno; | |
402 | ||
403 | /* Maximum number of cse-able expressions found. */ | |
404 | static int n_exprs; | |
405 | /* Maximum number of assignments for copy propagation found. */ | |
406 | static int n_sets; | |
407 | ||
408 | /* Table of registers that are modified. | |
409 | For each register, each element is a list of places where the pseudo-reg | |
410 | is set. | |
411 | ||
412 | For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only | |
413 | requires knowledge of which blocks kill which regs [and thus could use | |
f4e584dc | 414 | a bitmap instead of the lists `reg_set_table' uses]. |
7506f491 | 415 | |
f4e584dc JL |
416 | `reg_set_table' and could be turned into an array of bitmaps |
417 | (num-bbs x num-regs) | |
7506f491 DE |
418 | [however perhaps it may be useful to keep the data as is]. |
419 | One advantage of recording things this way is that `reg_set_table' is | |
420 | fairly sparse with respect to pseudo regs but for hard regs could be | |
421 | fairly dense [relatively speaking]. | |
422 | And recording sets of pseudo-regs in lists speeds | |
423 | up functions like compute_transp since in the case of pseudo-regs we only | |
424 | need to iterate over the number of times a pseudo-reg is set, not over the | |
425 | number of basic blocks [clearly there is a bit of a slow down in the cases | |
426 | where a pseudo is set more than once in a block, however it is believed | |
427 | that the net effect is to speed things up]. This isn't done for hard-regs | |
428 | because recording call-clobbered hard-regs in `reg_set_table' at each | |
429 | function call can consume a fair bit of memory, and iterating over hard-regs | |
430 | stored this way in compute_transp will be more expensive. */ | |
431 | ||
432 | typedef struct reg_set { | |
433 | /* The next setting of this register. */ | |
434 | struct reg_set *next; | |
435 | /* The insn where it was set. */ | |
436 | rtx insn; | |
437 | } reg_set; | |
438 | static reg_set **reg_set_table; | |
439 | /* Size of `reg_set_table'. | |
440 | The table starts out at max_gcse_regno + slop, and is enlarged as | |
441 | necessary. */ | |
442 | static int reg_set_table_size; | |
443 | /* Amount to grow `reg_set_table' by when it's full. */ | |
444 | #define REG_SET_TABLE_SLOP 100 | |
445 | ||
446 | /* Bitmap containing one bit for each register in the program. | |
447 | Used when performing GCSE to track which registers have been set since | |
448 | the start of the basic block. */ | |
449 | static sbitmap reg_set_bitmap; | |
450 | ||
451 | /* For each block, a bitmap of registers set in the block. | |
452 | This is used by expr_killed_p and compute_transp. | |
453 | It is computed during hash table computation and not by compute_sets | |
454 | as it includes registers added since the last pass (or between cprop and | |
455 | gcse) and it's currently not easy to realloc sbitmap vectors. */ | |
456 | static sbitmap *reg_set_in_block; | |
457 | ||
458 | /* For each block, non-zero if memory is set in that block. | |
459 | This is computed during hash table computation and is used by | |
460 | expr_killed_p and compute_transp. | |
461 | ??? Handling of memory is very simple, we don't make any attempt | |
462 | to optimize things (later). | |
463 | ??? This can be computed by compute_sets since the information | |
464 | doesn't change. */ | |
465 | static char *mem_set_in_block; | |
466 | ||
467 | /* Various variables for statistics gathering. */ | |
468 | ||
469 | /* Memory used in a pass. | |
470 | This isn't intended to be absolutely precise. Its intent is only | |
471 | to keep an eye on memory usage. */ | |
472 | static int bytes_used; | |
473 | /* GCSE substitutions made. */ | |
474 | static int gcse_subst_count; | |
475 | /* Number of copy instructions created. */ | |
476 | static int gcse_create_count; | |
477 | /* Number of constants propagated. */ | |
478 | static int const_prop_count; | |
479 | /* Number of copys propagated. */ | |
480 | static int copy_prop_count; | |
481 | ||
482 | extern char *current_function_name; | |
483 | extern int current_function_calls_setjmp; | |
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 | |
7506f491 | 513 | \f |
ac7c5af5 JL |
514 | static void compute_can_copy PROTO ((void)); |
515 | ||
516 | static char *gmalloc PROTO ((unsigned int)); | |
517 | static char *grealloc PROTO ((char *, unsigned int)); | |
518 | static char *gcse_alloc PROTO ((unsigned long)); | |
519 | static void alloc_gcse_mem PROTO ((rtx)); | |
520 | static void free_gcse_mem PROTO ((void)); | |
ac7c5af5 JL |
521 | static void alloc_reg_set_mem PROTO ((int)); |
522 | static void free_reg_set_mem PROTO ((void)); | |
523 | static void record_one_set PROTO ((int, rtx)); | |
524 | static void record_set_info PROTO ((rtx, rtx)); | |
525 | static void compute_sets PROTO ((rtx)); | |
526 | ||
527 | static void hash_scan_insn PROTO ((rtx, int, int)); | |
528 | static void hash_scan_set PROTO ((rtx, rtx, int)); | |
529 | static void hash_scan_clobber PROTO ((rtx, rtx)); | |
530 | static void hash_scan_call PROTO ((rtx, rtx)); | |
ac7c5af5 JL |
531 | static int want_to_gcse_p PROTO ((rtx)); |
532 | static int oprs_unchanged_p PROTO ((rtx, rtx, int)); | |
7506f491 | 533 | static int oprs_anticipatable_p PROTO ((rtx, rtx)); |
ac7c5af5 | 534 | static int oprs_available_p PROTO ((rtx, rtx)); |
b5ce41ff JL |
535 | static void insert_expr_in_table PROTO ((rtx, enum machine_mode, |
536 | rtx, int, int)); | |
7506f491 | 537 | static void insert_set_in_table PROTO ((rtx, rtx)); |
b5ce41ff JL |
538 | static unsigned int hash_expr PROTO ((rtx, enum machine_mode, |
539 | int *, int)); | |
7506f491 | 540 | static unsigned int hash_expr_1 PROTO ((rtx, enum machine_mode, int *)); |
ac7c5af5 JL |
541 | static unsigned int hash_set PROTO ((int, int)); |
542 | static int expr_equiv_p PROTO ((rtx, rtx)); | |
7506f491 DE |
543 | static void record_last_reg_set_info PROTO ((rtx, int)); |
544 | static void record_last_mem_set_info PROTO ((rtx)); | |
545 | static void record_last_set_info PROTO ((rtx, rtx)); | |
b5ce41ff | 546 | static void compute_hash_table PROTO ((int)); |
7506f491 DE |
547 | static void alloc_set_hash_table PROTO ((int)); |
548 | static void free_set_hash_table PROTO ((void)); | |
b5ce41ff | 549 | static void compute_set_hash_table PROTO ((void)); |
7506f491 DE |
550 | static void alloc_expr_hash_table PROTO ((int)); |
551 | static void free_expr_hash_table PROTO ((void)); | |
b5ce41ff | 552 | static void compute_expr_hash_table PROTO ((void)); |
a65f3558 JL |
553 | static void dump_hash_table PROTO ((FILE *, const char *, struct expr **, |
554 | int, int)); | |
7506f491 | 555 | static struct expr *lookup_expr PROTO ((rtx)); |
ac7c5af5 JL |
556 | static struct expr *lookup_set PROTO ((int, rtx)); |
557 | static struct expr *next_set PROTO ((int, struct expr *)); | |
7506f491 | 558 | static void reset_opr_set_tables PROTO ((void)); |
ac7c5af5 | 559 | static int oprs_not_set_p PROTO ((rtx, rtx)); |
b5ce41ff | 560 | static void mark_call PROTO ((rtx)); |
ac7c5af5 JL |
561 | static void mark_set PROTO ((rtx, rtx)); |
562 | static void mark_clobber PROTO ((rtx, rtx)); | |
563 | static void mark_oprs_set PROTO ((rtx)); | |
564 | ||
ac7c5af5 JL |
565 | static void alloc_cprop_mem PROTO ((int, int)); |
566 | static void free_cprop_mem PROTO ((void)); | |
ac7c5af5 | 567 | static void compute_transp PROTO ((rtx, int, sbitmap *, int)); |
a65f3558 | 568 | static void compute_transpout PROTO ((void)); |
b5ce41ff JL |
569 | static void compute_local_properties PROTO ((sbitmap *, sbitmap *, |
570 | sbitmap *, int)); | |
7506f491 | 571 | static void compute_cprop_avinout PROTO ((void)); |
ac7c5af5 JL |
572 | static void compute_cprop_data PROTO ((void)); |
573 | static void find_used_regs PROTO ((rtx)); | |
574 | static int try_replace_reg PROTO ((rtx, rtx, rtx)); | |
7506f491 | 575 | static struct expr *find_avail_set PROTO ((int, rtx)); |
b5ce41ff JL |
576 | static int cprop_insn PROTO ((rtx, int)); |
577 | static int cprop PROTO ((int)); | |
578 | static int one_cprop_pass PROTO ((int, int)); | |
7506f491 | 579 | |
ac7c5af5 JL |
580 | static void alloc_pre_mem PROTO ((int, int)); |
581 | static void free_pre_mem PROTO ((void)); | |
ac7c5af5 | 582 | static void compute_pre_data PROTO ((void)); |
a65f3558 JL |
583 | static int pre_expr_reaches_here_p PROTO ((int, struct expr *, |
584 | int, int, char *)); | |
585 | static void insert_insn_end_bb PROTO ((struct expr *, int, int)); | |
ac7c5af5 | 586 | static void pre_insert PROTO ((struct expr **)); |
7506f491 | 587 | static void pre_insert_copy_insn PROTO ((struct expr *, rtx)); |
ac7c5af5 JL |
588 | static void pre_insert_copies PROTO ((void)); |
589 | static int pre_delete PROTO ((void)); | |
590 | static int pre_gcse PROTO ((void)); | |
b5ce41ff | 591 | static int one_pre_gcse_pass PROTO ((int)); |
aeb2f500 JW |
592 | |
593 | static void add_label_notes PROTO ((rtx, rtx)); | |
b5ce41ff JL |
594 | |
595 | static void alloc_rd_mem PROTO ((int, int)); | |
596 | static void free_rd_mem PROTO ((void)); | |
597 | static void handle_rd_kill_set PROTO ((rtx, int, int)); | |
598 | static void compute_kill_rd PROTO ((void)); | |
599 | static void compute_rd PROTO ((void)); | |
600 | static void alloc_avail_expr_mem PROTO ((int, int)); | |
601 | static void free_avail_expr_mem PROTO ((void)); | |
602 | static void compute_ae_gen PROTO ((void)); | |
603 | static int expr_killed_p PROTO ((rtx, int)); | |
604 | static void compute_ae_kill PROTO ((void)); | |
605 | static void compute_available PROTO ((void)); | |
606 | static int expr_reaches_here_p PROTO ((struct occr *, struct expr *, | |
607 | int, int, char *)); | |
608 | static rtx computing_insn PROTO ((struct expr *, rtx)); | |
609 | static int def_reaches_here_p PROTO ((rtx, rtx)); | |
610 | static int can_disregard_other_sets PROTO ((struct reg_set **, rtx, int)); | |
611 | static int handle_avail_expr PROTO ((rtx, struct expr *)); | |
612 | static int classic_gcse PROTO ((void)); | |
613 | static int one_classic_gcse_pass PROTO ((int)); | |
614 | ||
7506f491 DE |
615 | \f |
616 | /* Entry point for global common subexpression elimination. | |
617 | F is the first instruction in the function. */ | |
618 | ||
e78d9500 | 619 | int |
7506f491 DE |
620 | gcse_main (f, file) |
621 | rtx f; | |
622 | FILE *file; | |
623 | { | |
624 | int changed, pass; | |
625 | /* Bytes used at start of pass. */ | |
626 | int initial_bytes_used; | |
627 | /* Maximum number of bytes used by a pass. */ | |
628 | int max_pass_bytes; | |
629 | /* Point to release obstack data from for each pass. */ | |
630 | char *gcse_obstack_bottom; | |
631 | ||
b5ce41ff JL |
632 | /* We do not construct an accurate cfg in functions which call |
633 | setjmp, so just punt to be safe. */ | |
7506f491 | 634 | if (current_function_calls_setjmp) |
e78d9500 | 635 | return 0; |
7506f491 | 636 | |
b5ce41ff JL |
637 | /* Assume that we do not need to run jump optimizations after gcse. */ |
638 | run_jump_opt_after_gcse = 0; | |
639 | ||
7506f491 DE |
640 | /* For calling dump_foo fns from gdb. */ |
641 | debug_stderr = stderr; | |
b5ce41ff | 642 | gcse_file = file; |
7506f491 | 643 | |
b5ce41ff JL |
644 | /* Identify the basic block information for this function, including |
645 | successors and predecessors. */ | |
7506f491 | 646 | max_gcse_regno = max_reg_num (); |
359da67d | 647 | find_basic_blocks (f, max_gcse_regno, file, 1); |
7506f491 DE |
648 | |
649 | /* Return if there's nothing to do. */ | |
650 | if (n_basic_blocks <= 1) | |
651 | { | |
652 | /* Free storage allocated by find_basic_blocks. */ | |
653 | free_basic_block_vars (0); | |
e78d9500 | 654 | return 0; |
7506f491 DE |
655 | } |
656 | ||
657 | /* See what modes support reg/reg copy operations. */ | |
658 | if (! can_copy_init_p) | |
659 | { | |
660 | compute_can_copy (); | |
661 | can_copy_init_p = 1; | |
662 | } | |
663 | ||
664 | gcc_obstack_init (&gcse_obstack); | |
665 | ||
7506f491 DE |
666 | /* Allocate and compute predecessors/successors. */ |
667 | ||
668 | s_preds = (int_list_ptr *) alloca (n_basic_blocks * sizeof (int_list_ptr)); | |
669 | s_succs = (int_list_ptr *) alloca (n_basic_blocks * sizeof (int_list_ptr)); | |
670 | num_preds = (int *) alloca (n_basic_blocks * sizeof (int)); | |
671 | num_succs = (int *) alloca (n_basic_blocks * sizeof (int)); | |
672 | bytes_used = 4 * n_basic_blocks * sizeof (int_list_ptr); | |
673 | compute_preds_succs (s_preds, s_succs, num_preds, num_succs); | |
674 | ||
675 | if (file) | |
421382ac | 676 | dump_bb_data (file, s_preds, s_succs, 0); |
7506f491 DE |
677 | |
678 | /* Record where pseudo-registers are set. | |
679 | This data is kept accurate during each pass. | |
b5ce41ff | 680 | ??? We could also record hard-reg information here |
7506f491 | 681 | [since it's unchanging], however it is currently done during |
b5ce41ff JL |
682 | hash table computation. |
683 | ||
684 | It may be tempting to compute MEM set information here too, but MEM | |
685 | sets will be subject to code motion one day and thus we need to compute | |
686 | information about memory sets when we build the hash tables. */ | |
7506f491 DE |
687 | |
688 | alloc_reg_set_mem (max_gcse_regno); | |
689 | compute_sets (f); | |
690 | ||
691 | pass = 0; | |
692 | initial_bytes_used = bytes_used; | |
693 | max_pass_bytes = 0; | |
694 | gcse_obstack_bottom = gcse_alloc (1); | |
695 | changed = 1; | |
696 | while (changed && pass < MAX_PASSES) | |
697 | { | |
698 | changed = 0; | |
699 | if (file) | |
700 | fprintf (file, "GCSE pass %d\n\n", pass + 1); | |
701 | ||
702 | /* Initialize bytes_used to the space for the pred/succ lists, | |
703 | and the reg_set_table data. */ | |
704 | bytes_used = initial_bytes_used; | |
705 | ||
706 | /* Each pass may create new registers, so recalculate each time. */ | |
707 | max_gcse_regno = max_reg_num (); | |
708 | ||
709 | alloc_gcse_mem (f); | |
710 | ||
b5ce41ff JL |
711 | /* Don't allow constant propagation to modify jumps |
712 | during this pass. */ | |
713 | changed = one_cprop_pass (pass + 1, 0); | |
7506f491 DE |
714 | |
715 | if (optimize_size) | |
b5ce41ff | 716 | changed |= one_classic_gcse_pass (pass + 1); |
7506f491 | 717 | else |
b5ce41ff | 718 | changed |= one_pre_gcse_pass (pass + 1); |
7506f491 DE |
719 | |
720 | if (max_pass_bytes < bytes_used) | |
721 | max_pass_bytes = bytes_used; | |
722 | ||
723 | free_gcse_mem (); | |
724 | ||
725 | if (file) | |
726 | { | |
727 | fprintf (file, "\n"); | |
728 | fflush (file); | |
729 | } | |
730 | obstack_free (&gcse_obstack, gcse_obstack_bottom); | |
731 | pass++; | |
732 | } | |
733 | ||
b5ce41ff JL |
734 | /* Do one last pass of copy propagation, including cprop into |
735 | conditional jumps. */ | |
736 | ||
737 | max_gcse_regno = max_reg_num (); | |
738 | alloc_gcse_mem (f); | |
739 | /* This time, go ahead and allow cprop to alter jumps. */ | |
740 | one_cprop_pass (pass + 1, 1); | |
741 | free_gcse_mem (); | |
7506f491 DE |
742 | |
743 | if (file) | |
744 | { | |
745 | fprintf (file, "GCSE of %s: %d basic blocks, ", | |
746 | current_function_name, n_basic_blocks); | |
747 | fprintf (file, "%d pass%s, %d bytes\n\n", | |
748 | pass, pass > 1 ? "es" : "", max_pass_bytes); | |
749 | } | |
750 | ||
751 | /* Free our obstack. */ | |
752 | obstack_free (&gcse_obstack, NULL_PTR); | |
753 | /* Free reg_set_table. */ | |
754 | free_reg_set_mem (); | |
755 | /* Free storage used to record predecessor/successor data. */ | |
756 | free_bb_mem (); | |
757 | /* Free storage allocated by find_basic_blocks. */ | |
758 | free_basic_block_vars (0); | |
e78d9500 | 759 | return run_jump_opt_after_gcse; |
7506f491 DE |
760 | } |
761 | \f | |
762 | /* Misc. utilities. */ | |
763 | ||
764 | /* Compute which modes support reg/reg copy operations. */ | |
765 | ||
766 | static void | |
767 | compute_can_copy () | |
768 | { | |
769 | int i; | |
50b2596f | 770 | #ifndef AVOID_CCMODE_COPIES |
7506f491 | 771 | rtx reg,insn; |
50b2596f | 772 | #endif |
7506f491 DE |
773 | char *free_point = (char *) oballoc (1); |
774 | ||
775 | bzero (can_copy_p, NUM_MACHINE_MODES); | |
776 | ||
777 | start_sequence (); | |
778 | for (i = 0; i < NUM_MACHINE_MODES; i++) | |
779 | { | |
780 | switch (GET_MODE_CLASS (i)) | |
781 | { | |
782 | case MODE_CC : | |
783 | #ifdef AVOID_CCMODE_COPIES | |
784 | can_copy_p[i] = 0; | |
785 | #else | |
9e6a5703 JC |
786 | reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1); |
787 | insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg)); | |
7506f491 DE |
788 | if (recog (PATTERN (insn), insn, NULL_PTR) >= 0) |
789 | can_copy_p[i] = 1; | |
790 | #endif | |
791 | break; | |
792 | default : | |
793 | can_copy_p[i] = 1; | |
794 | break; | |
795 | } | |
796 | } | |
797 | end_sequence (); | |
798 | ||
799 | /* Free the objects we just allocated. */ | |
800 | obfree (free_point); | |
801 | } | |
802 | \f | |
803 | /* Cover function to xmalloc to record bytes allocated. */ | |
804 | ||
805 | static char * | |
806 | gmalloc (size) | |
807 | unsigned int size; | |
808 | { | |
809 | bytes_used += size; | |
810 | return xmalloc (size); | |
811 | } | |
812 | ||
813 | /* Cover function to xrealloc. | |
814 | We don't record the additional size since we don't know it. | |
815 | It won't affect memory usage stats much anyway. */ | |
816 | ||
817 | static char * | |
818 | grealloc (ptr, size) | |
819 | char *ptr; | |
820 | unsigned int size; | |
821 | { | |
822 | return xrealloc (ptr, size); | |
823 | } | |
824 | ||
825 | /* Cover function to obstack_alloc. | |
826 | We don't need to record the bytes allocated here since | |
827 | obstack_chunk_alloc is set to gmalloc. */ | |
828 | ||
829 | static char * | |
830 | gcse_alloc (size) | |
831 | unsigned long size; | |
832 | { | |
833 | return (char *) obstack_alloc (&gcse_obstack, size); | |
834 | } | |
835 | ||
836 | /* Allocate memory for the cuid mapping array, | |
837 | and reg/memory set tracking tables. | |
838 | ||
839 | This is called at the start of each pass. */ | |
840 | ||
841 | static void | |
842 | alloc_gcse_mem (f) | |
843 | rtx f; | |
844 | { | |
845 | int i,n; | |
846 | rtx insn; | |
847 | ||
848 | /* Find the largest UID and create a mapping from UIDs to CUIDs. | |
849 | CUIDs are like UIDs except they increase monotonically, have no gaps, | |
850 | and only apply to real insns. */ | |
851 | ||
852 | max_uid = get_max_uid (); | |
853 | n = (max_uid + 1) * sizeof (int); | |
854 | uid_cuid = (int *) gmalloc (n); | |
855 | bzero ((char *) uid_cuid, n); | |
856 | for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) | |
857 | { | |
858 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
859 | INSN_CUID (insn) = i++; | |
860 | else | |
861 | INSN_CUID (insn) = i; | |
862 | } | |
863 | ||
864 | /* Create a table mapping cuids to insns. */ | |
865 | ||
866 | max_cuid = i; | |
867 | n = (max_cuid + 1) * sizeof (rtx); | |
868 | cuid_insn = (rtx *) gmalloc (n); | |
869 | bzero ((char *) cuid_insn, n); | |
870 | for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) | |
871 | { | |
872 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
873 | { | |
874 | CUID_INSN (i) = insn; | |
875 | i++; | |
876 | } | |
877 | } | |
878 | ||
879 | /* Allocate vars to track sets of regs. */ | |
880 | ||
881 | reg_set_bitmap = (sbitmap) sbitmap_alloc (max_gcse_regno); | |
882 | ||
883 | /* Allocate vars to track sets of regs, memory per block. */ | |
884 | ||
885 | reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (n_basic_blocks, | |
886 | max_gcse_regno); | |
887 | mem_set_in_block = (char *) gmalloc (n_basic_blocks); | |
888 | } | |
889 | ||
890 | /* Free memory allocated by alloc_gcse_mem. */ | |
891 | ||
892 | static void | |
893 | free_gcse_mem () | |
894 | { | |
895 | free (uid_cuid); | |
896 | free (cuid_insn); | |
897 | ||
898 | free (reg_set_bitmap); | |
899 | ||
900 | free (reg_set_in_block); | |
901 | free (mem_set_in_block); | |
902 | } | |
903 | ||
b5ce41ff JL |
904 | \f |
905 | /* Compute the local properties of each recorded expression. | |
906 | Local properties are those that are defined by the block, irrespective | |
907 | of other blocks. | |
908 | ||
909 | An expression is transparent in a block if its operands are not modified | |
910 | in the block. | |
911 | ||
912 | An expression is computed (locally available) in a block if it is computed | |
913 | at least once and expression would contain the same value if the | |
914 | computation was moved to the end of the block. | |
915 | ||
916 | An expression is locally anticipatable in a block if it is computed at | |
917 | least once and expression would contain the same value if the computation | |
918 | was moved to the beginning of the block. | |
919 | ||
920 | We call this routine for cprop, pre and code hoisting. They all | |
921 | compute basically the same information and thus can easily share | |
922 | this code. | |
7506f491 | 923 | |
b5ce41ff JL |
924 | TRANSP, COMP, and ANTLOC are destination sbitmaps for recording |
925 | local properties. If NULL, then it is not necessary to compute | |
926 | or record that particular property. | |
927 | ||
928 | SETP controls which hash table to look at. If zero, this routine | |
929 | looks at the expr hash table; if nonzero this routine looks at | |
930 | the set hash table. */ | |
931 | ||
932 | static void | |
933 | compute_local_properties (transp, comp, antloc, setp) | |
934 | sbitmap *transp; | |
935 | sbitmap *comp; | |
936 | sbitmap *antloc; | |
937 | int setp; | |
938 | { | |
939 | int i, hash_table_size; | |
940 | struct expr **hash_table; | |
941 | ||
942 | /* Initialize any bitmaps that were passed in. */ | |
943 | if (transp) | |
944 | sbitmap_vector_ones (transp, n_basic_blocks); | |
945 | if (comp) | |
946 | sbitmap_vector_zero (comp, n_basic_blocks); | |
947 | if (antloc) | |
948 | sbitmap_vector_zero (antloc, n_basic_blocks); | |
949 | ||
950 | /* We use the same code for cprop, pre and hoisting. For cprop | |
951 | we care about the set hash table, for pre and hoisting we | |
952 | care about the expr hash table. */ | |
953 | hash_table_size = setp ? set_hash_table_size : expr_hash_table_size; | |
954 | hash_table = setp ? set_hash_table : expr_hash_table; | |
955 | ||
956 | for (i = 0; i < hash_table_size; i++) | |
7506f491 | 957 | { |
b5ce41ff JL |
958 | struct expr *expr; |
959 | ||
960 | for (expr = hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
961 | { | |
962 | struct occr *occr; | |
963 | int indx = expr->bitmap_index; | |
964 | ||
965 | /* The expression is transparent in this block if it is not killed. | |
966 | We start by assuming all are transparent [none are killed], and | |
967 | then reset the bits for those that are. */ | |
968 | ||
969 | if (transp) | |
970 | compute_transp (expr->expr, indx, transp, setp); | |
971 | ||
972 | /* The occurrences recorded in antic_occr are exactly those that | |
973 | we want to set to non-zero in ANTLOC. */ | |
974 | ||
975 | if (antloc) | |
976 | { | |
977 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
978 | { | |
979 | int bb = BLOCK_NUM (occr->insn); | |
980 | SET_BIT (antloc[bb], indx); | |
981 | ||
982 | /* While we're scanning the table, this is a good place to | |
983 | initialize this. */ | |
984 | occr->deleted_p = 0; | |
985 | } | |
986 | } | |
987 | ||
988 | /* The occurrences recorded in avail_occr are exactly those that | |
989 | we want to set to non-zero in COMP. */ | |
990 | if (comp) | |
991 | { | |
992 | ||
993 | for (occr = expr->avail_occr; occr != NULL; occr = occr->next) | |
994 | { | |
995 | int bb = BLOCK_NUM (occr->insn); | |
996 | SET_BIT (comp[bb], indx); | |
997 | ||
998 | /* While we're scanning the table, this is a good place to | |
999 | initialize this. */ | |
1000 | occr->copied_p = 0; | |
1001 | } | |
1002 | } | |
1003 | ||
1004 | /* While we're scanning the table, this is a good place to | |
1005 | initialize this. */ | |
1006 | expr->reaching_reg = 0; | |
1007 | } | |
7506f491 | 1008 | } |
7506f491 | 1009 | } |
b5ce41ff | 1010 | |
7506f491 DE |
1011 | \f |
1012 | /* Register set information. | |
1013 | ||
1014 | `reg_set_table' records where each register is set or otherwise | |
1015 | modified. */ | |
1016 | ||
1017 | static struct obstack reg_set_obstack; | |
1018 | ||
1019 | static void | |
1020 | alloc_reg_set_mem (n_regs) | |
1021 | int n_regs; | |
1022 | { | |
1023 | int n; | |
1024 | ||
1025 | reg_set_table_size = n_regs + REG_SET_TABLE_SLOP; | |
1026 | n = reg_set_table_size * sizeof (struct reg_set *); | |
1027 | reg_set_table = (struct reg_set **) gmalloc (n); | |
1028 | bzero ((char *) reg_set_table, n); | |
1029 | ||
1030 | gcc_obstack_init (®_set_obstack); | |
1031 | } | |
1032 | ||
1033 | static void | |
1034 | free_reg_set_mem () | |
1035 | { | |
1036 | free (reg_set_table); | |
1037 | obstack_free (®_set_obstack, NULL_PTR); | |
1038 | } | |
1039 | ||
1040 | /* Record REGNO in the reg_set table. */ | |
1041 | ||
1042 | static void | |
1043 | record_one_set (regno, insn) | |
1044 | int regno; | |
1045 | rtx insn; | |
1046 | { | |
1047 | /* allocate a new reg_set element and link it onto the list */ | |
1048 | struct reg_set *new_reg_info, *reg_info_ptr1, *reg_info_ptr2; | |
1049 | ||
1050 | /* If the table isn't big enough, enlarge it. */ | |
1051 | if (regno >= reg_set_table_size) | |
1052 | { | |
1053 | int new_size = regno + REG_SET_TABLE_SLOP; | |
1054 | reg_set_table = (struct reg_set **) | |
1055 | grealloc ((char *) reg_set_table, | |
1056 | new_size * sizeof (struct reg_set *)); | |
1057 | bzero ((char *) (reg_set_table + reg_set_table_size), | |
1058 | (new_size - reg_set_table_size) * sizeof (struct reg_set *)); | |
1059 | reg_set_table_size = new_size; | |
1060 | } | |
1061 | ||
1062 | new_reg_info = (struct reg_set *) obstack_alloc (®_set_obstack, | |
1063 | sizeof (struct reg_set)); | |
1064 | bytes_used += sizeof (struct reg_set); | |
1065 | new_reg_info->insn = insn; | |
1066 | new_reg_info->next = NULL; | |
1067 | if (reg_set_table[regno] == NULL) | |
1068 | reg_set_table[regno] = new_reg_info; | |
1069 | else | |
1070 | { | |
1071 | reg_info_ptr1 = reg_info_ptr2 = reg_set_table[regno]; | |
1072 | /* ??? One could keep a "last" pointer to speed this up. */ | |
1073 | while (reg_info_ptr1 != NULL) | |
1074 | { | |
1075 | reg_info_ptr2 = reg_info_ptr1; | |
1076 | reg_info_ptr1 = reg_info_ptr1->next; | |
1077 | } | |
1078 | reg_info_ptr2->next = new_reg_info; | |
1079 | } | |
1080 | } | |
1081 | ||
1082 | /* For communication between next two functions (via note_stores). */ | |
1083 | static rtx record_set_insn; | |
1084 | ||
1085 | /* Called from compute_sets via note_stores to handle one | |
1086 | SET or CLOBBER in an insn. */ | |
1087 | ||
1088 | static void | |
1089 | record_set_info (dest, setter) | |
50b2596f | 1090 | rtx dest, setter ATTRIBUTE_UNUSED; |
7506f491 DE |
1091 | { |
1092 | if (GET_CODE (dest) == SUBREG) | |
1093 | dest = SUBREG_REG (dest); | |
1094 | ||
1095 | if (GET_CODE (dest) == REG) | |
1096 | { | |
1097 | if (REGNO (dest) >= FIRST_PSEUDO_REGISTER) | |
1098 | record_one_set (REGNO (dest), record_set_insn); | |
1099 | } | |
1100 | } | |
1101 | ||
1102 | /* Scan the function and record each set of each pseudo-register. | |
1103 | ||
1104 | This is called once, at the start of the gcse pass. | |
1105 | See the comments for `reg_set_table' for further docs. */ | |
1106 | ||
1107 | static void | |
1108 | compute_sets (f) | |
1109 | rtx f; | |
1110 | { | |
1111 | rtx insn = f; | |
1112 | ||
1113 | while (insn) | |
1114 | { | |
1115 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
1116 | { | |
1117 | record_set_insn = insn; | |
1118 | note_stores (PATTERN (insn), record_set_info); | |
1119 | } | |
1120 | insn = NEXT_INSN (insn); | |
1121 | } | |
1122 | } | |
1123 | \f | |
1124 | /* Hash table support. */ | |
1125 | ||
b86ba9c8 GK |
1126 | #define NEVER_SET -1 |
1127 | ||
7506f491 | 1128 | /* For each register, the cuid of the first/last insn in the block to set it, |
e7d99f1e | 1129 | or -1 if not set. */ |
7506f491 DE |
1130 | static int *reg_first_set; |
1131 | static int *reg_last_set; | |
1132 | ||
1133 | /* While computing "first/last set" info, this is the CUID of first/last insn | |
e7d99f1e | 1134 | to set memory or -1 if not set. `mem_last_set' is also used when |
7506f491 DE |
1135 | performing GCSE to record whether memory has been set since the beginning |
1136 | of the block. | |
1137 | Note that handling of memory is very simple, we don't make any attempt | |
1138 | to optimize things (later). */ | |
1139 | static int mem_first_set; | |
1140 | static int mem_last_set; | |
1141 | ||
7506f491 DE |
1142 | /* Perform a quick check whether X, the source of a set, is something |
1143 | we want to consider for GCSE. */ | |
1144 | ||
1145 | static int | |
1146 | want_to_gcse_p (x) | |
1147 | rtx x; | |
1148 | { | |
1149 | enum rtx_code code = GET_CODE (x); | |
1150 | ||
1151 | switch (code) | |
1152 | { | |
1153 | case REG: | |
1154 | case SUBREG: | |
1155 | case CONST_INT: | |
1156 | case CONST_DOUBLE: | |
1157 | case CALL: | |
1158 | return 0; | |
1159 | ||
1160 | default: | |
1161 | break; | |
1162 | } | |
1163 | ||
1164 | return 1; | |
1165 | } | |
1166 | ||
1167 | /* Return non-zero if the operands of expression X are unchanged from the | |
1168 | start of INSN's basic block up to but not including INSN (if AVAIL_P == 0), | |
1169 | or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */ | |
1170 | ||
1171 | static int | |
1172 | oprs_unchanged_p (x, insn, avail_p) | |
1173 | rtx x, insn; | |
1174 | int avail_p; | |
1175 | { | |
1176 | int i; | |
1177 | enum rtx_code code; | |
1178 | char *fmt; | |
1179 | ||
1180 | /* repeat is used to turn tail-recursion into iteration. */ | |
1181 | repeat: | |
1182 | ||
1183 | if (x == 0) | |
1184 | return 1; | |
1185 | ||
1186 | code = GET_CODE (x); | |
1187 | switch (code) | |
1188 | { | |
1189 | case REG: | |
1190 | if (avail_p) | |
b86ba9c8 | 1191 | return (reg_last_set[REGNO (x)] == NEVER_SET |
7506f491 DE |
1192 | || reg_last_set[REGNO (x)] < INSN_CUID (insn)); |
1193 | else | |
b86ba9c8 | 1194 | return (reg_first_set[REGNO (x)] == NEVER_SET |
7506f491 DE |
1195 | || reg_first_set[REGNO (x)] >= INSN_CUID (insn)); |
1196 | ||
1197 | case MEM: | |
1198 | if (avail_p) | |
1199 | { | |
b86ba9c8 | 1200 | if (mem_last_set != NEVER_SET |
7506f491 DE |
1201 | && mem_last_set >= INSN_CUID (insn)) |
1202 | return 0; | |
1203 | } | |
1204 | else | |
1205 | { | |
b86ba9c8 | 1206 | if (mem_first_set != NEVER_SET |
7506f491 DE |
1207 | && mem_first_set < INSN_CUID (insn)) |
1208 | return 0; | |
1209 | } | |
1210 | x = XEXP (x, 0); | |
1211 | goto repeat; | |
1212 | ||
1213 | case PRE_DEC: | |
1214 | case PRE_INC: | |
1215 | case POST_DEC: | |
1216 | case POST_INC: | |
1217 | return 0; | |
1218 | ||
1219 | case PC: | |
1220 | case CC0: /*FIXME*/ | |
1221 | case CONST: | |
1222 | case CONST_INT: | |
1223 | case CONST_DOUBLE: | |
1224 | case SYMBOL_REF: | |
1225 | case LABEL_REF: | |
1226 | case ADDR_VEC: | |
1227 | case ADDR_DIFF_VEC: | |
1228 | return 1; | |
1229 | ||
1230 | default: | |
1231 | break; | |
1232 | } | |
1233 | ||
1234 | i = GET_RTX_LENGTH (code) - 1; | |
1235 | fmt = GET_RTX_FORMAT (code); | |
1236 | for (; i >= 0; i--) | |
1237 | { | |
1238 | if (fmt[i] == 'e') | |
1239 | { | |
1240 | rtx tem = XEXP (x, i); | |
1241 | ||
1242 | /* If we are about to do the last recursive call | |
1243 | needed at this level, change it into iteration. | |
1244 | This function is called enough to be worth it. */ | |
1245 | if (i == 0) | |
1246 | { | |
1247 | x = tem; | |
1248 | goto repeat; | |
1249 | } | |
1250 | if (! oprs_unchanged_p (tem, insn, avail_p)) | |
1251 | return 0; | |
1252 | } | |
1253 | else if (fmt[i] == 'E') | |
1254 | { | |
1255 | int j; | |
1256 | for (j = 0; j < XVECLEN (x, i); j++) | |
1257 | { | |
1258 | if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p)) | |
1259 | return 0; | |
1260 | } | |
1261 | } | |
1262 | } | |
1263 | ||
1264 | return 1; | |
1265 | } | |
1266 | ||
1267 | /* Return non-zero if the operands of expression X are unchanged from | |
1268 | the start of INSN's basic block up to but not including INSN. */ | |
1269 | ||
1270 | static int | |
1271 | oprs_anticipatable_p (x, insn) | |
1272 | rtx x, insn; | |
1273 | { | |
1274 | return oprs_unchanged_p (x, insn, 0); | |
1275 | } | |
1276 | ||
1277 | /* Return non-zero if the operands of expression X are unchanged from | |
1278 | INSN to the end of INSN's basic block. */ | |
1279 | ||
1280 | static int | |
1281 | oprs_available_p (x, insn) | |
1282 | rtx x, insn; | |
1283 | { | |
1284 | return oprs_unchanged_p (x, insn, 1); | |
1285 | } | |
1286 | ||
1287 | /* Hash expression X. | |
1288 | MODE is only used if X is a CONST_INT. | |
1289 | A boolean indicating if a volatile operand is found or if the expression | |
1290 | contains something we don't want to insert in the table is stored in | |
1291 | DO_NOT_RECORD_P. | |
1292 | ||
1293 | ??? One might want to merge this with canon_hash. Later. */ | |
1294 | ||
1295 | static unsigned int | |
1296 | hash_expr (x, mode, do_not_record_p, hash_table_size) | |
1297 | rtx x; | |
1298 | enum machine_mode mode; | |
1299 | int *do_not_record_p; | |
1300 | int hash_table_size; | |
1301 | { | |
1302 | unsigned int hash; | |
1303 | ||
1304 | *do_not_record_p = 0; | |
1305 | ||
1306 | hash = hash_expr_1 (x, mode, do_not_record_p); | |
1307 | return hash % hash_table_size; | |
1308 | } | |
1309 | ||
1310 | /* Subroutine of hash_expr to do the actual work. */ | |
1311 | ||
1312 | static unsigned int | |
1313 | hash_expr_1 (x, mode, do_not_record_p) | |
1314 | rtx x; | |
1315 | enum machine_mode mode; | |
1316 | int *do_not_record_p; | |
1317 | { | |
1318 | int i, j; | |
1319 | unsigned hash = 0; | |
1320 | enum rtx_code code; | |
1321 | char *fmt; | |
1322 | ||
1323 | /* repeat is used to turn tail-recursion into iteration. */ | |
1324 | repeat: | |
1325 | ||
1326 | if (x == 0) | |
1327 | return hash; | |
1328 | ||
1329 | code = GET_CODE (x); | |
1330 | switch (code) | |
1331 | { | |
1332 | case REG: | |
1333 | { | |
1334 | register int regno = REGNO (x); | |
1335 | hash += ((unsigned) REG << 7) + regno; | |
1336 | return hash; | |
1337 | } | |
1338 | ||
1339 | case CONST_INT: | |
1340 | { | |
1341 | unsigned HOST_WIDE_INT tem = INTVAL (x); | |
1342 | hash += ((unsigned) CONST_INT << 7) + (unsigned) mode + tem; | |
1343 | return hash; | |
1344 | } | |
1345 | ||
1346 | case CONST_DOUBLE: | |
1347 | /* This is like the general case, except that it only counts | |
1348 | the integers representing the constant. */ | |
1349 | hash += (unsigned) code + (unsigned) GET_MODE (x); | |
1350 | if (GET_MODE (x) != VOIDmode) | |
1351 | for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++) | |
1352 | { | |
1353 | unsigned tem = XINT (x, i); | |
1354 | hash += tem; | |
1355 | } | |
1356 | else | |
1357 | hash += ((unsigned) CONST_DOUBLE_LOW (x) | |
1358 | + (unsigned) CONST_DOUBLE_HIGH (x)); | |
1359 | return hash; | |
1360 | ||
1361 | /* Assume there is only one rtx object for any given label. */ | |
1362 | case LABEL_REF: | |
1363 | /* We don't hash on the address of the CODE_LABEL to avoid bootstrap | |
1364 | differences and differences between each stage's debugging dumps. */ | |
1365 | hash += ((unsigned) LABEL_REF << 7) + CODE_LABEL_NUMBER (XEXP (x, 0)); | |
1366 | return hash; | |
1367 | ||
1368 | case SYMBOL_REF: | |
1369 | { | |
1370 | /* Don't hash on the symbol's address to avoid bootstrap differences. | |
1371 | Different hash values may cause expressions to be recorded in | |
1372 | different orders and thus different registers to be used in the | |
1373 | final assembler. This also avoids differences in the dump files | |
1374 | between various stages. */ | |
1375 | unsigned int h = 0; | |
1376 | unsigned char *p = (unsigned char *) XSTR (x, 0); | |
1377 | while (*p) | |
1378 | h += (h << 7) + *p++; /* ??? revisit */ | |
1379 | hash += ((unsigned) SYMBOL_REF << 7) + h; | |
1380 | return hash; | |
1381 | } | |
1382 | ||
1383 | case MEM: | |
1384 | if (MEM_VOLATILE_P (x)) | |
1385 | { | |
1386 | *do_not_record_p = 1; | |
1387 | return 0; | |
1388 | } | |
1389 | hash += (unsigned) MEM; | |
1390 | x = XEXP (x, 0); | |
1391 | goto repeat; | |
1392 | ||
1393 | case PRE_DEC: | |
1394 | case PRE_INC: | |
1395 | case POST_DEC: | |
1396 | case POST_INC: | |
1397 | case PC: | |
1398 | case CC0: | |
1399 | case CALL: | |
1400 | case UNSPEC_VOLATILE: | |
1401 | *do_not_record_p = 1; | |
1402 | return 0; | |
1403 | ||
1404 | case ASM_OPERANDS: | |
1405 | if (MEM_VOLATILE_P (x)) | |
1406 | { | |
1407 | *do_not_record_p = 1; | |
1408 | return 0; | |
1409 | } | |
1410 | ||
1411 | default: | |
1412 | break; | |
1413 | } | |
1414 | ||
1415 | i = GET_RTX_LENGTH (code) - 1; | |
1416 | hash += (unsigned) code + (unsigned) GET_MODE (x); | |
1417 | fmt = GET_RTX_FORMAT (code); | |
1418 | for (; i >= 0; i--) | |
1419 | { | |
1420 | if (fmt[i] == 'e') | |
1421 | { | |
1422 | rtx tem = XEXP (x, i); | |
1423 | ||
1424 | /* If we are about to do the last recursive call | |
1425 | needed at this level, change it into iteration. | |
1426 | This function is called enough to be worth it. */ | |
1427 | if (i == 0) | |
1428 | { | |
1429 | x = tem; | |
1430 | goto repeat; | |
1431 | } | |
1432 | hash += hash_expr_1 (tem, 0, do_not_record_p); | |
1433 | if (*do_not_record_p) | |
1434 | return 0; | |
1435 | } | |
1436 | else if (fmt[i] == 'E') | |
1437 | for (j = 0; j < XVECLEN (x, i); j++) | |
1438 | { | |
1439 | hash += hash_expr_1 (XVECEXP (x, i, j), 0, do_not_record_p); | |
1440 | if (*do_not_record_p) | |
1441 | return 0; | |
1442 | } | |
1443 | else if (fmt[i] == 's') | |
1444 | { | |
1445 | register unsigned char *p = (unsigned char *) XSTR (x, i); | |
1446 | if (p) | |
1447 | while (*p) | |
1448 | hash += *p++; | |
1449 | } | |
1450 | else if (fmt[i] == 'i') | |
1451 | { | |
1452 | register unsigned tem = XINT (x, i); | |
1453 | hash += tem; | |
1454 | } | |
1455 | else | |
1456 | abort (); | |
1457 | } | |
1458 | ||
1459 | return hash; | |
1460 | } | |
1461 | ||
1462 | /* Hash a set of register REGNO. | |
1463 | ||
1464 | Sets are hashed on the register that is set. | |
1465 | This simplifies the PRE copy propagation code. | |
1466 | ||
1467 | ??? May need to make things more elaborate. Later, as necessary. */ | |
1468 | ||
1469 | static unsigned int | |
1470 | hash_set (regno, hash_table_size) | |
1471 | int regno; | |
1472 | int hash_table_size; | |
1473 | { | |
1474 | unsigned int hash; | |
1475 | ||
1476 | hash = regno; | |
1477 | return hash % hash_table_size; | |
1478 | } | |
1479 | ||
1480 | /* Return non-zero if exp1 is equivalent to exp2. | |
1481 | ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */ | |
1482 | ||
1483 | static int | |
1484 | expr_equiv_p (x, y) | |
1485 | rtx x, y; | |
1486 | { | |
1487 | register int i, j; | |
1488 | register enum rtx_code code; | |
1489 | register char *fmt; | |
1490 | ||
1491 | if (x == y) | |
1492 | return 1; | |
1493 | if (x == 0 || y == 0) | |
1494 | return x == y; | |
1495 | ||
1496 | code = GET_CODE (x); | |
1497 | if (code != GET_CODE (y)) | |
1498 | return 0; | |
1499 | ||
1500 | /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */ | |
1501 | if (GET_MODE (x) != GET_MODE (y)) | |
1502 | return 0; | |
1503 | ||
1504 | switch (code) | |
1505 | { | |
1506 | case PC: | |
1507 | case CC0: | |
1508 | return x == y; | |
1509 | ||
1510 | case CONST_INT: | |
1511 | return INTVAL (x) == INTVAL (y); | |
1512 | ||
1513 | case LABEL_REF: | |
1514 | return XEXP (x, 0) == XEXP (y, 0); | |
1515 | ||
1516 | case SYMBOL_REF: | |
1517 | return XSTR (x, 0) == XSTR (y, 0); | |
1518 | ||
1519 | case REG: | |
1520 | return REGNO (x) == REGNO (y); | |
1521 | ||
1522 | /* For commutative operations, check both orders. */ | |
1523 | case PLUS: | |
1524 | case MULT: | |
1525 | case AND: | |
1526 | case IOR: | |
1527 | case XOR: | |
1528 | case NE: | |
1529 | case EQ: | |
1530 | return ((expr_equiv_p (XEXP (x, 0), XEXP (y, 0)) | |
1531 | && expr_equiv_p (XEXP (x, 1), XEXP (y, 1))) | |
1532 | || (expr_equiv_p (XEXP (x, 0), XEXP (y, 1)) | |
1533 | && expr_equiv_p (XEXP (x, 1), XEXP (y, 0)))); | |
1534 | ||
1535 | default: | |
1536 | break; | |
1537 | } | |
1538 | ||
1539 | /* Compare the elements. If any pair of corresponding elements | |
1540 | fail to match, return 0 for the whole thing. */ | |
1541 | ||
1542 | fmt = GET_RTX_FORMAT (code); | |
1543 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
1544 | { | |
1545 | switch (fmt[i]) | |
1546 | { | |
1547 | case 'e': | |
1548 | if (! expr_equiv_p (XEXP (x, i), XEXP (y, i))) | |
1549 | return 0; | |
1550 | break; | |
1551 | ||
1552 | case 'E': | |
1553 | if (XVECLEN (x, i) != XVECLEN (y, i)) | |
1554 | return 0; | |
1555 | for (j = 0; j < XVECLEN (x, i); j++) | |
1556 | if (! expr_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j))) | |
1557 | return 0; | |
1558 | break; | |
1559 | ||
1560 | case 's': | |
1561 | if (strcmp (XSTR (x, i), XSTR (y, i))) | |
1562 | return 0; | |
1563 | break; | |
1564 | ||
1565 | case 'i': | |
1566 | if (XINT (x, i) != XINT (y, i)) | |
1567 | return 0; | |
1568 | break; | |
1569 | ||
1570 | case 'w': | |
1571 | if (XWINT (x, i) != XWINT (y, i)) | |
1572 | return 0; | |
1573 | break; | |
1574 | ||
1575 | case '0': | |
1576 | break; | |
1577 | ||
1578 | default: | |
1579 | abort (); | |
1580 | } | |
1581 | } | |
1582 | ||
1583 | return 1; | |
1584 | } | |
1585 | ||
1586 | /* Insert expression X in INSN in the hash table. | |
1587 | If it is already present, record it as the last occurrence in INSN's | |
1588 | basic block. | |
1589 | ||
1590 | MODE is the mode of the value X is being stored into. | |
1591 | It is only used if X is a CONST_INT. | |
1592 | ||
1593 | ANTIC_P is non-zero if X is an anticipatable expression. | |
1594 | AVAIL_P is non-zero if X is an available expression. */ | |
1595 | ||
1596 | static void | |
1597 | insert_expr_in_table (x, mode, insn, antic_p, avail_p) | |
1598 | rtx x; | |
1599 | enum machine_mode mode; | |
1600 | rtx insn; | |
1601 | int antic_p, avail_p; | |
1602 | { | |
1603 | int found, do_not_record_p; | |
1604 | unsigned int hash; | |
1605 | struct expr *cur_expr, *last_expr = NULL; | |
1606 | struct occr *antic_occr, *avail_occr; | |
1607 | struct occr *last_occr = NULL; | |
1608 | ||
1609 | hash = hash_expr (x, mode, &do_not_record_p, expr_hash_table_size); | |
1610 | ||
1611 | /* Do not insert expression in table if it contains volatile operands, | |
1612 | or if hash_expr determines the expression is something we don't want | |
1613 | to or can't handle. */ | |
1614 | if (do_not_record_p) | |
1615 | return; | |
1616 | ||
1617 | cur_expr = expr_hash_table[hash]; | |
1618 | found = 0; | |
1619 | ||
1620 | while (cur_expr && ! (found = expr_equiv_p (cur_expr->expr, x))) | |
1621 | { | |
1622 | /* If the expression isn't found, save a pointer to the end of | |
1623 | the list. */ | |
1624 | last_expr = cur_expr; | |
1625 | cur_expr = cur_expr->next_same_hash; | |
1626 | } | |
1627 | ||
1628 | if (! found) | |
1629 | { | |
1630 | cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr)); | |
1631 | bytes_used += sizeof (struct expr); | |
1632 | if (expr_hash_table[hash] == NULL) | |
1633 | { | |
1634 | /* This is the first pattern that hashed to this index. */ | |
1635 | expr_hash_table[hash] = cur_expr; | |
1636 | } | |
1637 | else | |
1638 | { | |
1639 | /* Add EXPR to end of this hash chain. */ | |
1640 | last_expr->next_same_hash = cur_expr; | |
1641 | } | |
1642 | /* Set the fields of the expr element. */ | |
1643 | cur_expr->expr = x; | |
1644 | cur_expr->bitmap_index = n_exprs++; | |
1645 | cur_expr->next_same_hash = NULL; | |
1646 | cur_expr->antic_occr = NULL; | |
1647 | cur_expr->avail_occr = NULL; | |
1648 | } | |
1649 | ||
1650 | /* Now record the occurrence(s). */ | |
1651 | ||
1652 | if (antic_p) | |
1653 | { | |
1654 | antic_occr = cur_expr->antic_occr; | |
1655 | ||
1656 | /* Search for another occurrence in the same basic block. */ | |
1657 | while (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn)) | |
1658 | { | |
1659 | /* If an occurrence isn't found, save a pointer to the end of | |
1660 | the list. */ | |
1661 | last_occr = antic_occr; | |
1662 | antic_occr = antic_occr->next; | |
1663 | } | |
1664 | ||
1665 | if (antic_occr) | |
1666 | { | |
1667 | /* Found another instance of the expression in the same basic block. | |
1668 | Prefer the currently recorded one. We want the first one in the | |
1669 | block and the block is scanned from start to end. */ | |
1670 | ; /* nothing to do */ | |
1671 | } | |
1672 | else | |
1673 | { | |
1674 | /* First occurrence of this expression in this basic block. */ | |
1675 | antic_occr = (struct occr *) gcse_alloc (sizeof (struct occr)); | |
1676 | bytes_used += sizeof (struct occr); | |
1677 | /* First occurrence of this expression in any block? */ | |
1678 | if (cur_expr->antic_occr == NULL) | |
1679 | cur_expr->antic_occr = antic_occr; | |
1680 | else | |
1681 | last_occr->next = antic_occr; | |
1682 | antic_occr->insn = insn; | |
1683 | antic_occr->next = NULL; | |
1684 | } | |
1685 | } | |
1686 | ||
1687 | if (avail_p) | |
1688 | { | |
1689 | avail_occr = cur_expr->avail_occr; | |
1690 | ||
1691 | /* Search for another occurrence in the same basic block. */ | |
1692 | while (avail_occr && BLOCK_NUM (avail_occr->insn) != BLOCK_NUM (insn)) | |
1693 | { | |
1694 | /* If an occurrence isn't found, save a pointer to the end of | |
1695 | the list. */ | |
1696 | last_occr = avail_occr; | |
1697 | avail_occr = avail_occr->next; | |
1698 | } | |
1699 | ||
1700 | if (avail_occr) | |
1701 | { | |
1702 | /* Found another instance of the expression in the same basic block. | |
1703 | Prefer this occurrence to the currently recorded one. We want | |
1704 | the last one in the block and the block is scanned from start | |
1705 | to end. */ | |
1706 | avail_occr->insn = insn; | |
1707 | } | |
1708 | else | |
1709 | { | |
1710 | /* First occurrence of this expression in this basic block. */ | |
1711 | avail_occr = (struct occr *) gcse_alloc (sizeof (struct occr)); | |
1712 | bytes_used += sizeof (struct occr); | |
1713 | /* First occurrence of this expression in any block? */ | |
1714 | if (cur_expr->avail_occr == NULL) | |
1715 | cur_expr->avail_occr = avail_occr; | |
1716 | else | |
1717 | last_occr->next = avail_occr; | |
1718 | avail_occr->insn = insn; | |
1719 | avail_occr->next = NULL; | |
1720 | } | |
1721 | } | |
1722 | } | |
1723 | ||
1724 | /* Insert pattern X in INSN in the hash table. | |
1725 | X is a SET of a reg to either another reg or a constant. | |
1726 | If it is already present, record it as the last occurrence in INSN's | |
1727 | basic block. */ | |
1728 | ||
1729 | static void | |
1730 | insert_set_in_table (x, insn) | |
1731 | rtx x; | |
1732 | rtx insn; | |
1733 | { | |
1734 | int found; | |
1735 | unsigned int hash; | |
1736 | struct expr *cur_expr, *last_expr = NULL; | |
1737 | struct occr *cur_occr, *last_occr = NULL; | |
1738 | ||
1739 | if (GET_CODE (x) != SET | |
1740 | || GET_CODE (SET_DEST (x)) != REG) | |
1741 | abort (); | |
1742 | ||
1743 | hash = hash_set (REGNO (SET_DEST (x)), set_hash_table_size); | |
1744 | ||
1745 | cur_expr = set_hash_table[hash]; | |
1746 | found = 0; | |
1747 | ||
1748 | while (cur_expr && ! (found = expr_equiv_p (cur_expr->expr, x))) | |
1749 | { | |
1750 | /* If the expression isn't found, save a pointer to the end of | |
1751 | the list. */ | |
1752 | last_expr = cur_expr; | |
1753 | cur_expr = cur_expr->next_same_hash; | |
1754 | } | |
1755 | ||
1756 | if (! found) | |
1757 | { | |
1758 | cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr)); | |
1759 | bytes_used += sizeof (struct expr); | |
1760 | if (set_hash_table[hash] == NULL) | |
1761 | { | |
1762 | /* This is the first pattern that hashed to this index. */ | |
1763 | set_hash_table[hash] = cur_expr; | |
1764 | } | |
1765 | else | |
1766 | { | |
1767 | /* Add EXPR to end of this hash chain. */ | |
1768 | last_expr->next_same_hash = cur_expr; | |
1769 | } | |
1770 | /* Set the fields of the expr element. | |
1771 | We must copy X because it can be modified when copy propagation is | |
1772 | performed on its operands. */ | |
1773 | /* ??? Should this go in a different obstack? */ | |
1774 | cur_expr->expr = copy_rtx (x); | |
1775 | cur_expr->bitmap_index = n_sets++; | |
1776 | cur_expr->next_same_hash = NULL; | |
1777 | cur_expr->antic_occr = NULL; | |
1778 | cur_expr->avail_occr = NULL; | |
1779 | } | |
1780 | ||
1781 | /* Now record the occurrence. */ | |
1782 | ||
1783 | cur_occr = cur_expr->avail_occr; | |
1784 | ||
1785 | /* Search for another occurrence in the same basic block. */ | |
1786 | while (cur_occr && BLOCK_NUM (cur_occr->insn) != BLOCK_NUM (insn)) | |
1787 | { | |
1788 | /* If an occurrence isn't found, save a pointer to the end of | |
1789 | the list. */ | |
1790 | last_occr = cur_occr; | |
1791 | cur_occr = cur_occr->next; | |
1792 | } | |
1793 | ||
1794 | if (cur_occr) | |
1795 | { | |
1796 | /* Found another instance of the expression in the same basic block. | |
1797 | Prefer this occurrence to the currently recorded one. We want | |
1798 | the last one in the block and the block is scanned from start | |
1799 | to end. */ | |
1800 | cur_occr->insn = insn; | |
1801 | } | |
1802 | else | |
1803 | { | |
1804 | /* First occurrence of this expression in this basic block. */ | |
1805 | cur_occr = (struct occr *) gcse_alloc (sizeof (struct occr)); | |
1806 | bytes_used += sizeof (struct occr); | |
1807 | /* First occurrence of this expression in any block? */ | |
1808 | if (cur_expr->avail_occr == NULL) | |
1809 | cur_expr->avail_occr = cur_occr; | |
1810 | else | |
1811 | last_occr->next = cur_occr; | |
1812 | cur_occr->insn = insn; | |
1813 | cur_occr->next = NULL; | |
1814 | } | |
1815 | } | |
1816 | ||
1817 | /* Scan pattern PAT of INSN and add an entry to the hash table. | |
1818 | If SET_P is non-zero, this is for the assignment hash table, | |
1819 | otherwise it is for the expression hash table. */ | |
1820 | ||
1821 | static void | |
1822 | hash_scan_set (pat, insn, set_p) | |
1823 | rtx pat, insn; | |
1824 | int set_p; | |
1825 | { | |
1826 | rtx src = SET_SRC (pat); | |
1827 | rtx dest = SET_DEST (pat); | |
1828 | ||
1829 | if (GET_CODE (src) == CALL) | |
1830 | hash_scan_call (src, insn); | |
1831 | ||
1832 | if (GET_CODE (dest) == REG) | |
1833 | { | |
1834 | int regno = REGNO (dest); | |
1835 | rtx tmp; | |
1836 | ||
1837 | /* Only record sets of pseudo-regs in the hash table. */ | |
1838 | if (! set_p | |
1839 | && regno >= FIRST_PSEUDO_REGISTER | |
1840 | /* Don't GCSE something if we can't do a reg/reg copy. */ | |
1841 | && can_copy_p [GET_MODE (dest)] | |
1842 | /* Is SET_SRC something we want to gcse? */ | |
1843 | && want_to_gcse_p (src)) | |
1844 | { | |
1845 | /* An expression is not anticipatable if its operands are | |
1846 | modified before this insn. */ | |
1847 | int antic_p = ! optimize_size && oprs_anticipatable_p (src, insn); | |
1848 | /* An expression is not available if its operands are | |
1849 | subsequently modified, including this insn. */ | |
1850 | int avail_p = oprs_available_p (src, insn); | |
1851 | insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p); | |
1852 | } | |
1853 | /* Record sets for constant/copy propagation. */ | |
1854 | else if (set_p | |
1855 | && regno >= FIRST_PSEUDO_REGISTER | |
1856 | && ((GET_CODE (src) == REG | |
1857 | && REGNO (src) >= FIRST_PSEUDO_REGISTER | |
1858 | && can_copy_p [GET_MODE (dest)]) | |
1859 | /* ??? CONST_INT:wip */ | |
e78d9500 JL |
1860 | || GET_CODE (src) == CONST_INT |
1861 | || GET_CODE (src) == CONST_DOUBLE) | |
7506f491 DE |
1862 | /* A copy is not available if its src or dest is subsequently |
1863 | modified. Here we want to search from INSN+1 on, but | |
1864 | oprs_available_p searches from INSN on. */ | |
1865 | && (insn == BLOCK_END (BLOCK_NUM (insn)) | |
1866 | || ((tmp = next_nonnote_insn (insn)) != NULL_RTX | |
1867 | && oprs_available_p (pat, tmp)))) | |
1868 | insert_set_in_table (pat, insn); | |
1869 | } | |
7506f491 DE |
1870 | } |
1871 | ||
1872 | static void | |
1873 | hash_scan_clobber (x, insn) | |
50b2596f | 1874 | rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED; |
7506f491 DE |
1875 | { |
1876 | /* Currently nothing to do. */ | |
1877 | } | |
1878 | ||
1879 | static void | |
1880 | hash_scan_call (x, insn) | |
50b2596f | 1881 | rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED; |
7506f491 DE |
1882 | { |
1883 | /* Currently nothing to do. */ | |
1884 | } | |
1885 | ||
1886 | /* Process INSN and add hash table entries as appropriate. | |
1887 | ||
1888 | Only available expressions that set a single pseudo-reg are recorded. | |
1889 | ||
1890 | Single sets in a PARALLEL could be handled, but it's an extra complication | |
1891 | that isn't dealt with right now. The trick is handling the CLOBBERs that | |
1892 | are also in the PARALLEL. Later. | |
1893 | ||
1894 | If SET_P is non-zero, this is for the assignment hash table, | |
ed79bb3d R |
1895 | otherwise it is for the expression hash table. |
1896 | If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should | |
1897 | not record any expressions. */ | |
7506f491 DE |
1898 | |
1899 | static void | |
ed79bb3d | 1900 | hash_scan_insn (insn, set_p, in_libcall_block) |
7506f491 DE |
1901 | rtx insn; |
1902 | int set_p; | |
48e87cef | 1903 | int in_libcall_block; |
7506f491 DE |
1904 | { |
1905 | rtx pat = PATTERN (insn); | |
1906 | ||
1907 | /* Pick out the sets of INSN and for other forms of instructions record | |
1908 | what's been modified. */ | |
1909 | ||
ed79bb3d | 1910 | if (GET_CODE (pat) == SET && ! in_libcall_block) |
7506f491 DE |
1911 | hash_scan_set (pat, insn, set_p); |
1912 | else if (GET_CODE (pat) == PARALLEL) | |
1913 | { | |
1914 | int i; | |
1915 | ||
1916 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
1917 | { | |
1918 | rtx x = XVECEXP (pat, 0, i); | |
1919 | ||
1920 | if (GET_CODE (x) == SET) | |
1921 | { | |
1922 | if (GET_CODE (SET_SRC (x)) == CALL) | |
1923 | hash_scan_call (SET_SRC (x), insn); | |
7506f491 DE |
1924 | } |
1925 | else if (GET_CODE (x) == CLOBBER) | |
1926 | hash_scan_clobber (x, insn); | |
1927 | else if (GET_CODE (x) == CALL) | |
1928 | hash_scan_call (x, insn); | |
1929 | } | |
1930 | } | |
1931 | else if (GET_CODE (pat) == CLOBBER) | |
1932 | hash_scan_clobber (pat, insn); | |
1933 | else if (GET_CODE (pat) == CALL) | |
1934 | hash_scan_call (pat, insn); | |
1935 | } | |
1936 | ||
1937 | static void | |
1938 | dump_hash_table (file, name, table, table_size, total_size) | |
1939 | FILE *file; | |
dff01034 | 1940 | const char *name; |
7506f491 DE |
1941 | struct expr **table; |
1942 | int table_size, total_size; | |
1943 | { | |
1944 | int i; | |
1945 | /* Flattened out table, so it's printed in proper order. */ | |
1946 | struct expr **flat_table = (struct expr **) alloca (total_size * sizeof (struct expr *)); | |
1947 | unsigned int *hash_val = (unsigned int *) alloca (total_size * sizeof (unsigned int)); | |
1948 | ||
1949 | bzero ((char *) flat_table, total_size * sizeof (struct expr *)); | |
1950 | for (i = 0; i < table_size; i++) | |
1951 | { | |
1952 | struct expr *expr; | |
1953 | ||
1954 | for (expr = table[i]; expr != NULL; expr = expr->next_same_hash) | |
1955 | { | |
1956 | flat_table[expr->bitmap_index] = expr; | |
1957 | hash_val[expr->bitmap_index] = i; | |
1958 | } | |
1959 | } | |
1960 | ||
1961 | fprintf (file, "%s hash table (%d buckets, %d entries)\n", | |
1962 | name, table_size, total_size); | |
1963 | ||
1964 | for (i = 0; i < total_size; i++) | |
1965 | { | |
1966 | struct expr *expr = flat_table[i]; | |
1967 | ||
1968 | fprintf (file, "Index %d (hash value %d)\n ", | |
1969 | expr->bitmap_index, hash_val[i]); | |
1970 | print_rtl (file, expr->expr); | |
1971 | fprintf (file, "\n"); | |
1972 | } | |
1973 | ||
1974 | fprintf (file, "\n"); | |
1975 | } | |
1976 | ||
1977 | /* Record register first/last/block set information for REGNO in INSN. | |
1978 | reg_first_set records the first place in the block where the register | |
1979 | is set and is used to compute "anticipatability". | |
1980 | reg_last_set records the last place in the block where the register | |
1981 | is set and is used to compute "availability". | |
1982 | reg_set_in_block records whether the register is set in the block | |
1983 | and is used to compute "transparency". */ | |
1984 | ||
1985 | static void | |
1986 | record_last_reg_set_info (insn, regno) | |
1987 | rtx insn; | |
1988 | int regno; | |
1989 | { | |
b86ba9c8 | 1990 | if (reg_first_set[regno] == NEVER_SET) |
7506f491 DE |
1991 | reg_first_set[regno] = INSN_CUID (insn); |
1992 | reg_last_set[regno] = INSN_CUID (insn); | |
1993 | SET_BIT (reg_set_in_block[BLOCK_NUM (insn)], regno); | |
1994 | } | |
1995 | ||
1996 | /* Record memory first/last/block set information for INSN. */ | |
1997 | ||
1998 | static void | |
1999 | record_last_mem_set_info (insn) | |
2000 | rtx insn; | |
2001 | { | |
b86ba9c8 | 2002 | if (mem_first_set == NEVER_SET) |
7506f491 DE |
2003 | mem_first_set = INSN_CUID (insn); |
2004 | mem_last_set = INSN_CUID (insn); | |
2005 | mem_set_in_block[BLOCK_NUM (insn)] = 1; | |
2006 | } | |
2007 | ||
2008 | /* Used for communicating between next two routines. */ | |
2009 | static rtx last_set_insn; | |
2010 | ||
2011 | /* Called from compute_hash_table via note_stores to handle one | |
2012 | SET or CLOBBER in an insn. */ | |
2013 | ||
2014 | static void | |
2015 | record_last_set_info (dest, setter) | |
50b2596f | 2016 | rtx dest, setter ATTRIBUTE_UNUSED; |
7506f491 DE |
2017 | { |
2018 | if (GET_CODE (dest) == SUBREG) | |
2019 | dest = SUBREG_REG (dest); | |
2020 | ||
2021 | if (GET_CODE (dest) == REG) | |
2022 | record_last_reg_set_info (last_set_insn, REGNO (dest)); | |
2023 | else if (GET_CODE (dest) == MEM | |
2024 | /* Ignore pushes, they clobber nothing. */ | |
2025 | && ! push_operand (dest, GET_MODE (dest))) | |
2026 | record_last_mem_set_info (last_set_insn); | |
2027 | } | |
2028 | ||
2029 | /* Top level function to create an expression or assignment hash table. | |
2030 | ||
2031 | Expression entries are placed in the hash table if | |
2032 | - they are of the form (set (pseudo-reg) src), | |
2033 | - src is something we want to perform GCSE on, | |
2034 | - none of the operands are subsequently modified in the block | |
2035 | ||
2036 | Assignment entries are placed in the hash table if | |
2037 | - they are of the form (set (pseudo-reg) src), | |
2038 | - src is something we want to perform const/copy propagation on, | |
2039 | - none of the operands or target are subsequently modified in the block | |
2040 | Currently src must be a pseudo-reg or a const_int. | |
2041 | ||
2042 | F is the first insn. | |
2043 | SET_P is non-zero for computing the assignment hash table. */ | |
2044 | ||
2045 | static void | |
b5ce41ff | 2046 | compute_hash_table (set_p) |
7506f491 DE |
2047 | int set_p; |
2048 | { | |
2049 | int bb; | |
2050 | ||
2051 | /* While we compute the hash table we also compute a bit array of which | |
2052 | registers are set in which blocks. | |
2053 | We also compute which blocks set memory, in the absence of aliasing | |
2054 | support [which is TODO]. | |
2055 | ??? This isn't needed during const/copy propagation, but it's cheap to | |
2056 | compute. Later. */ | |
2057 | sbitmap_vector_zero (reg_set_in_block, n_basic_blocks); | |
2058 | bzero ((char *) mem_set_in_block, n_basic_blocks); | |
2059 | ||
2060 | /* Some working arrays used to track first and last set in each block. */ | |
2061 | /* ??? One could use alloca here, but at some size a threshold is crossed | |
2062 | beyond which one should use malloc. Are we at that threshold here? */ | |
2063 | reg_first_set = (int *) gmalloc (max_gcse_regno * sizeof (int)); | |
2064 | reg_last_set = (int *) gmalloc (max_gcse_regno * sizeof (int)); | |
2065 | ||
2066 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2067 | { | |
2068 | rtx insn; | |
2069 | int regno; | |
ed79bb3d | 2070 | int in_libcall_block; |
b86ba9c8 | 2071 | int i; |
7506f491 DE |
2072 | |
2073 | /* First pass over the instructions records information used to | |
2074 | determine when registers and memory are first and last set. | |
2075 | ??? The mem_set_in_block and hard-reg reg_set_in_block computation | |
2076 | could be moved to compute_sets since they currently don't change. */ | |
2077 | ||
b86ba9c8 GK |
2078 | for (i = 0; i < max_gcse_regno; i++) |
2079 | reg_first_set[i] = reg_last_set[i] = NEVER_SET; | |
2080 | mem_first_set = NEVER_SET; | |
2081 | mem_last_set = NEVER_SET; | |
7506f491 | 2082 | |
3b413743 RH |
2083 | for (insn = BLOCK_HEAD (bb); |
2084 | insn && insn != NEXT_INSN (BLOCK_END (bb)); | |
7506f491 DE |
2085 | insn = NEXT_INSN (insn)) |
2086 | { | |
2087 | #ifdef NON_SAVING_SETJMP | |
2088 | if (NON_SAVING_SETJMP && GET_CODE (insn) == NOTE | |
2089 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP) | |
2090 | { | |
2091 | for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) | |
2092 | record_last_reg_set_info (insn, regno); | |
2093 | continue; | |
2094 | } | |
2095 | #endif | |
2096 | ||
2097 | if (GET_RTX_CLASS (GET_CODE (insn)) != 'i') | |
2098 | continue; | |
2099 | ||
2100 | if (GET_CODE (insn) == CALL_INSN) | |
2101 | { | |
2102 | for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) | |
15f8470f JL |
2103 | if ((call_used_regs[regno] |
2104 | && regno != STACK_POINTER_REGNUM | |
2105 | #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2106 | && regno != HARD_FRAME_POINTER_REGNUM | |
2107 | #endif | |
2108 | #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2109 | && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno]) | |
2110 | #endif | |
2111 | #if defined (PIC_OFFSET_TABLE_REGNUM) && !defined (PIC_OFFSET_TABLE_REG_CALL_CLOBBERED) | |
2112 | && ! (regno == PIC_OFFSET_TABLE_REGNUM && flag_pic) | |
2113 | #endif | |
2114 | ||
2115 | && regno != FRAME_POINTER_REGNUM) | |
2116 | || global_regs[regno]) | |
7506f491 DE |
2117 | record_last_reg_set_info (insn, regno); |
2118 | if (! CONST_CALL_P (insn)) | |
2119 | record_last_mem_set_info (insn); | |
2120 | } | |
2121 | ||
2122 | last_set_insn = insn; | |
2123 | note_stores (PATTERN (insn), record_last_set_info); | |
2124 | } | |
2125 | ||
2126 | /* The next pass builds the hash table. */ | |
2127 | ||
3b413743 RH |
2128 | for (insn = BLOCK_HEAD (bb), in_libcall_block = 0; |
2129 | insn && insn != NEXT_INSN (BLOCK_END (bb)); | |
7506f491 DE |
2130 | insn = NEXT_INSN (insn)) |
2131 | { | |
2132 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
ed79bb3d R |
2133 | { |
2134 | if (find_reg_note (insn, REG_LIBCALL, NULL_RTX)) | |
2135 | in_libcall_block = 1; | |
2136 | else if (find_reg_note (insn, REG_RETVAL, NULL_RTX)) | |
2137 | in_libcall_block = 0; | |
2138 | hash_scan_insn (insn, set_p, in_libcall_block); | |
2139 | } | |
7506f491 DE |
2140 | } |
2141 | } | |
2142 | ||
2143 | free (reg_first_set); | |
2144 | free (reg_last_set); | |
2145 | /* Catch bugs early. */ | |
2146 | reg_first_set = reg_last_set = 0; | |
2147 | } | |
2148 | ||
2149 | /* Allocate space for the set hash table. | |
2150 | N_INSNS is the number of instructions in the function. | |
2151 | It is used to determine the number of buckets to use. */ | |
2152 | ||
2153 | static void | |
2154 | alloc_set_hash_table (n_insns) | |
2155 | int n_insns; | |
2156 | { | |
2157 | int n; | |
2158 | ||
2159 | set_hash_table_size = n_insns / 4; | |
2160 | if (set_hash_table_size < 11) | |
2161 | set_hash_table_size = 11; | |
2162 | /* Attempt to maintain efficient use of hash table. | |
2163 | Making it an odd number is simplest for now. | |
2164 | ??? Later take some measurements. */ | |
2165 | set_hash_table_size |= 1; | |
2166 | n = set_hash_table_size * sizeof (struct expr *); | |
2167 | set_hash_table = (struct expr **) gmalloc (n); | |
2168 | } | |
2169 | ||
2170 | /* Free things allocated by alloc_set_hash_table. */ | |
2171 | ||
2172 | static void | |
2173 | free_set_hash_table () | |
2174 | { | |
2175 | free (set_hash_table); | |
2176 | } | |
2177 | ||
2178 | /* Compute the hash table for doing copy/const propagation. */ | |
2179 | ||
2180 | static void | |
b5ce41ff | 2181 | compute_set_hash_table () |
7506f491 DE |
2182 | { |
2183 | /* Initialize count of number of entries in hash table. */ | |
2184 | n_sets = 0; | |
2185 | bzero ((char *) set_hash_table, set_hash_table_size * sizeof (struct expr *)); | |
2186 | ||
b5ce41ff | 2187 | compute_hash_table (1); |
7506f491 DE |
2188 | } |
2189 | ||
2190 | /* Allocate space for the expression hash table. | |
2191 | N_INSNS is the number of instructions in the function. | |
2192 | It is used to determine the number of buckets to use. */ | |
2193 | ||
2194 | static void | |
2195 | alloc_expr_hash_table (n_insns) | |
2196 | int n_insns; | |
2197 | { | |
2198 | int n; | |
2199 | ||
2200 | expr_hash_table_size = n_insns / 2; | |
2201 | /* Make sure the amount is usable. */ | |
2202 | if (expr_hash_table_size < 11) | |
2203 | expr_hash_table_size = 11; | |
2204 | /* Attempt to maintain efficient use of hash table. | |
2205 | Making it an odd number is simplest for now. | |
2206 | ??? Later take some measurements. */ | |
2207 | expr_hash_table_size |= 1; | |
2208 | n = expr_hash_table_size * sizeof (struct expr *); | |
2209 | expr_hash_table = (struct expr **) gmalloc (n); | |
2210 | } | |
2211 | ||
2212 | /* Free things allocated by alloc_expr_hash_table. */ | |
2213 | ||
2214 | static void | |
2215 | free_expr_hash_table () | |
2216 | { | |
2217 | free (expr_hash_table); | |
2218 | } | |
2219 | ||
2220 | /* Compute the hash table for doing GCSE. */ | |
2221 | ||
2222 | static void | |
b5ce41ff | 2223 | compute_expr_hash_table () |
7506f491 DE |
2224 | { |
2225 | /* Initialize count of number of entries in hash table. */ | |
2226 | n_exprs = 0; | |
2227 | bzero ((char *) expr_hash_table, expr_hash_table_size * sizeof (struct expr *)); | |
2228 | ||
b5ce41ff | 2229 | compute_hash_table (0); |
7506f491 DE |
2230 | } |
2231 | \f | |
2232 | /* Expression tracking support. */ | |
2233 | ||
2234 | /* Lookup pattern PAT in the expression table. | |
2235 | The result is a pointer to the table entry, or NULL if not found. */ | |
2236 | ||
2237 | static struct expr * | |
2238 | lookup_expr (pat) | |
2239 | rtx pat; | |
2240 | { | |
2241 | int do_not_record_p; | |
2242 | unsigned int hash = hash_expr (pat, GET_MODE (pat), &do_not_record_p, | |
2243 | expr_hash_table_size); | |
2244 | struct expr *expr; | |
2245 | ||
2246 | if (do_not_record_p) | |
2247 | return NULL; | |
2248 | ||
2249 | expr = expr_hash_table[hash]; | |
2250 | ||
2251 | while (expr && ! expr_equiv_p (expr->expr, pat)) | |
2252 | expr = expr->next_same_hash; | |
2253 | ||
2254 | return expr; | |
2255 | } | |
2256 | ||
2257 | /* Lookup REGNO in the set table. | |
2258 | If PAT is non-NULL look for the entry that matches it, otherwise return | |
2259 | the first entry for REGNO. | |
2260 | The result is a pointer to the table entry, or NULL if not found. */ | |
2261 | ||
2262 | static struct expr * | |
2263 | lookup_set (regno, pat) | |
2264 | int regno; | |
2265 | rtx pat; | |
2266 | { | |
2267 | unsigned int hash = hash_set (regno, set_hash_table_size); | |
2268 | struct expr *expr; | |
2269 | ||
2270 | expr = set_hash_table[hash]; | |
2271 | ||
2272 | if (pat) | |
2273 | { | |
2274 | while (expr && ! expr_equiv_p (expr->expr, pat)) | |
2275 | expr = expr->next_same_hash; | |
2276 | } | |
2277 | else | |
2278 | { | |
2279 | while (expr && REGNO (SET_DEST (expr->expr)) != regno) | |
2280 | expr = expr->next_same_hash; | |
2281 | } | |
2282 | ||
2283 | return expr; | |
2284 | } | |
2285 | ||
2286 | /* Return the next entry for REGNO in list EXPR. */ | |
2287 | ||
2288 | static struct expr * | |
2289 | next_set (regno, expr) | |
2290 | int regno; | |
2291 | struct expr *expr; | |
2292 | { | |
2293 | do | |
2294 | expr = expr->next_same_hash; | |
2295 | while (expr && REGNO (SET_DEST (expr->expr)) != regno); | |
2296 | return expr; | |
2297 | } | |
2298 | ||
2299 | /* Reset tables used to keep track of what's still available [since the | |
2300 | start of the block]. */ | |
2301 | ||
2302 | static void | |
2303 | reset_opr_set_tables () | |
2304 | { | |
2305 | /* Maintain a bitmap of which regs have been set since beginning of | |
2306 | the block. */ | |
2307 | sbitmap_zero (reg_set_bitmap); | |
2308 | /* Also keep a record of the last instruction to modify memory. | |
2309 | For now this is very trivial, we only record whether any memory | |
2310 | location has been modified. */ | |
2311 | mem_last_set = 0; | |
2312 | } | |
2313 | ||
2314 | /* Return non-zero if the operands of X are not set before INSN in | |
2315 | INSN's basic block. */ | |
2316 | ||
2317 | static int | |
2318 | oprs_not_set_p (x, insn) | |
2319 | rtx x, insn; | |
2320 | { | |
2321 | int i; | |
2322 | enum rtx_code code; | |
2323 | char *fmt; | |
2324 | ||
2325 | /* repeat is used to turn tail-recursion into iteration. */ | |
2326 | repeat: | |
2327 | ||
2328 | if (x == 0) | |
2329 | return 1; | |
2330 | ||
2331 | code = GET_CODE (x); | |
2332 | switch (code) | |
2333 | { | |
2334 | case PC: | |
2335 | case CC0: | |
2336 | case CONST: | |
2337 | case CONST_INT: | |
2338 | case CONST_DOUBLE: | |
2339 | case SYMBOL_REF: | |
2340 | case LABEL_REF: | |
2341 | case ADDR_VEC: | |
2342 | case ADDR_DIFF_VEC: | |
2343 | return 1; | |
2344 | ||
2345 | case MEM: | |
2346 | if (mem_last_set != 0) | |
2347 | return 0; | |
2348 | x = XEXP (x, 0); | |
2349 | goto repeat; | |
2350 | ||
2351 | case REG: | |
2352 | return ! TEST_BIT (reg_set_bitmap, REGNO (x)); | |
2353 | ||
2354 | default: | |
2355 | break; | |
2356 | } | |
2357 | ||
2358 | fmt = GET_RTX_FORMAT (code); | |
2359 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2360 | { | |
2361 | if (fmt[i] == 'e') | |
2362 | { | |
2363 | int not_set_p; | |
2364 | /* If we are about to do the last recursive call | |
2365 | needed at this level, change it into iteration. | |
2366 | This function is called enough to be worth it. */ | |
2367 | if (i == 0) | |
2368 | { | |
2369 | x = XEXP (x, 0); | |
2370 | goto repeat; | |
2371 | } | |
2372 | not_set_p = oprs_not_set_p (XEXP (x, i), insn); | |
2373 | if (! not_set_p) | |
2374 | return 0; | |
2375 | } | |
2376 | else if (fmt[i] == 'E') | |
2377 | { | |
2378 | int j; | |
2379 | for (j = 0; j < XVECLEN (x, i); j++) | |
2380 | { | |
2381 | int not_set_p = oprs_not_set_p (XVECEXP (x, i, j), insn); | |
2382 | if (! not_set_p) | |
2383 | return 0; | |
2384 | } | |
2385 | } | |
2386 | } | |
2387 | ||
2388 | return 1; | |
2389 | } | |
2390 | ||
2391 | /* Mark things set by a CALL. */ | |
2392 | ||
2393 | static void | |
b5ce41ff JL |
2394 | mark_call (insn) |
2395 | rtx insn; | |
7506f491 DE |
2396 | { |
2397 | mem_last_set = INSN_CUID (insn); | |
2398 | } | |
2399 | ||
2400 | /* Mark things set by a SET. */ | |
2401 | ||
2402 | static void | |
2403 | mark_set (pat, insn) | |
2404 | rtx pat, insn; | |
2405 | { | |
2406 | rtx dest = SET_DEST (pat); | |
2407 | ||
2408 | while (GET_CODE (dest) == SUBREG | |
2409 | || GET_CODE (dest) == ZERO_EXTRACT | |
2410 | || GET_CODE (dest) == SIGN_EXTRACT | |
2411 | || GET_CODE (dest) == STRICT_LOW_PART) | |
2412 | dest = XEXP (dest, 0); | |
2413 | ||
2414 | if (GET_CODE (dest) == REG) | |
2415 | SET_BIT (reg_set_bitmap, REGNO (dest)); | |
2416 | else if (GET_CODE (dest) == MEM) | |
2417 | mem_last_set = INSN_CUID (insn); | |
2418 | ||
2419 | if (GET_CODE (SET_SRC (pat)) == CALL) | |
b5ce41ff | 2420 | mark_call (insn); |
7506f491 DE |
2421 | } |
2422 | ||
2423 | /* Record things set by a CLOBBER. */ | |
2424 | ||
2425 | static void | |
2426 | mark_clobber (pat, insn) | |
2427 | rtx pat, insn; | |
2428 | { | |
2429 | rtx clob = XEXP (pat, 0); | |
2430 | ||
2431 | while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART) | |
2432 | clob = XEXP (clob, 0); | |
2433 | ||
2434 | if (GET_CODE (clob) == REG) | |
2435 | SET_BIT (reg_set_bitmap, REGNO (clob)); | |
2436 | else | |
2437 | mem_last_set = INSN_CUID (insn); | |
2438 | } | |
2439 | ||
2440 | /* Record things set by INSN. | |
2441 | This data is used by oprs_not_set_p. */ | |
2442 | ||
2443 | static void | |
2444 | mark_oprs_set (insn) | |
2445 | rtx insn; | |
2446 | { | |
2447 | rtx pat = PATTERN (insn); | |
2448 | ||
2449 | if (GET_CODE (pat) == SET) | |
2450 | mark_set (pat, insn); | |
2451 | else if (GET_CODE (pat) == PARALLEL) | |
2452 | { | |
2453 | int i; | |
2454 | ||
2455 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
2456 | { | |
2457 | rtx x = XVECEXP (pat, 0, i); | |
2458 | ||
2459 | if (GET_CODE (x) == SET) | |
2460 | mark_set (x, insn); | |
2461 | else if (GET_CODE (x) == CLOBBER) | |
2462 | mark_clobber (x, insn); | |
2463 | else if (GET_CODE (x) == CALL) | |
b5ce41ff | 2464 | mark_call (insn); |
7506f491 DE |
2465 | } |
2466 | } | |
2467 | else if (GET_CODE (pat) == CLOBBER) | |
2468 | mark_clobber (pat, insn); | |
2469 | else if (GET_CODE (pat) == CALL) | |
b5ce41ff | 2470 | mark_call (insn); |
7506f491 | 2471 | } |
b5ce41ff | 2472 | |
7506f491 DE |
2473 | \f |
2474 | /* Classic GCSE reaching definition support. */ | |
2475 | ||
2476 | /* Allocate reaching def variables. */ | |
2477 | ||
2478 | static void | |
2479 | alloc_rd_mem (n_blocks, n_insns) | |
2480 | int n_blocks, n_insns; | |
2481 | { | |
2482 | rd_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2483 | sbitmap_vector_zero (rd_kill, n_basic_blocks); | |
2484 | ||
2485 | rd_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2486 | sbitmap_vector_zero (rd_gen, n_basic_blocks); | |
2487 | ||
2488 | reaching_defs = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2489 | sbitmap_vector_zero (reaching_defs, n_basic_blocks); | |
2490 | ||
2491 | rd_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2492 | sbitmap_vector_zero (rd_out, n_basic_blocks); | |
2493 | } | |
2494 | ||
2495 | /* Free reaching def variables. */ | |
2496 | ||
2497 | static void | |
2498 | free_rd_mem () | |
2499 | { | |
2500 | free (rd_kill); | |
2501 | free (rd_gen); | |
2502 | free (reaching_defs); | |
2503 | free (rd_out); | |
2504 | } | |
2505 | ||
2506 | /* Add INSN to the kills of BB. | |
2507 | REGNO, set in BB, is killed by INSN. */ | |
2508 | ||
2509 | static void | |
2510 | handle_rd_kill_set (insn, regno, bb) | |
2511 | rtx insn; | |
2512 | int regno, bb; | |
2513 | { | |
2514 | struct reg_set *this_reg = reg_set_table[regno]; | |
2515 | ||
2516 | while (this_reg) | |
2517 | { | |
2518 | if (BLOCK_NUM (this_reg->insn) != BLOCK_NUM (insn)) | |
2519 | SET_BIT (rd_kill[bb], INSN_CUID (this_reg->insn)); | |
2520 | this_reg = this_reg->next; | |
2521 | } | |
2522 | } | |
2523 | ||
7506f491 DE |
2524 | /* Compute the set of kill's for reaching definitions. */ |
2525 | ||
2526 | static void | |
2527 | compute_kill_rd () | |
2528 | { | |
2529 | int bb,cuid; | |
2530 | ||
2531 | /* For each block | |
2532 | For each set bit in `gen' of the block (i.e each insn which | |
ac7c5af5 JL |
2533 | generates a definition in the block) |
2534 | Call the reg set by the insn corresponding to that bit regx | |
2535 | Look at the linked list starting at reg_set_table[regx] | |
2536 | For each setting of regx in the linked list, which is not in | |
2537 | this block | |
2538 | Set the bit in `kill' corresponding to that insn | |
7506f491 DE |
2539 | */ |
2540 | ||
2541 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2542 | { | |
2543 | for (cuid = 0; cuid < max_cuid; cuid++) | |
2544 | { | |
2545 | if (TEST_BIT (rd_gen[bb], cuid)) | |
ac7c5af5 | 2546 | { |
7506f491 DE |
2547 | rtx insn = CUID_INSN (cuid); |
2548 | rtx pat = PATTERN (insn); | |
2549 | ||
2550 | if (GET_CODE (insn) == CALL_INSN) | |
ac7c5af5 | 2551 | { |
7506f491 DE |
2552 | int regno; |
2553 | ||
2554 | for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) | |
ac7c5af5 | 2555 | { |
15f8470f JL |
2556 | if ((call_used_regs[regno] |
2557 | && regno != STACK_POINTER_REGNUM | |
2558 | #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2559 | && regno != HARD_FRAME_POINTER_REGNUM | |
2560 | #endif | |
2561 | #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2562 | && ! (regno == ARG_POINTER_REGNUM | |
2563 | && fixed_regs[regno]) | |
2564 | #endif | |
2565 | #if defined (PIC_OFFSET_TABLE_REGNUM) && !defined (PIC_OFFSET_TABLE_REG_CALL_CLOBBERED) | |
2566 | && ! (regno == PIC_OFFSET_TABLE_REGNUM && flag_pic) | |
2567 | #endif | |
2568 | && regno != FRAME_POINTER_REGNUM) | |
2569 | || global_regs[regno]) | |
7506f491 | 2570 | handle_rd_kill_set (insn, regno, bb); |
ac7c5af5 JL |
2571 | } |
2572 | } | |
7506f491 DE |
2573 | |
2574 | if (GET_CODE (pat) == PARALLEL) | |
2575 | { | |
2576 | int i; | |
2577 | ||
2578 | /* We work backwards because ... */ | |
2579 | for (i = XVECLEN (pat, 0) - 1; i >= 0; i--) | |
2580 | { | |
2581 | enum rtx_code code = GET_CODE (XVECEXP (pat, 0, i)); | |
2582 | if ((code == SET || code == CLOBBER) | |
2583 | && GET_CODE (XEXP (XVECEXP (pat, 0, i), 0)) == REG) | |
2584 | handle_rd_kill_set (insn, | |
2585 | REGNO (XEXP (XVECEXP (pat, 0, i), 0)), | |
2586 | bb); | |
2587 | } | |
2588 | } | |
2589 | else if (GET_CODE (pat) == SET) | |
2590 | { | |
2591 | if (GET_CODE (SET_DEST (pat)) == REG) | |
2592 | { | |
2593 | /* Each setting of this register outside of this block | |
2594 | must be marked in the set of kills in this block. */ | |
2595 | handle_rd_kill_set (insn, REGNO (SET_DEST (pat)), bb); | |
2596 | } | |
ac7c5af5 | 2597 | } |
7506f491 | 2598 | /* FIXME: CLOBBER? */ |
ac7c5af5 | 2599 | } |
7506f491 DE |
2600 | } |
2601 | } | |
2602 | } | |
2603 | ||
2604 | /* Compute the reaching definitions as in | |
2605 | Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman, | |
2606 | Chapter 10. It is the same algorithm as used for computing available | |
2607 | expressions but applied to the gens and kills of reaching definitions. */ | |
2608 | ||
2609 | static void | |
2610 | compute_rd () | |
2611 | { | |
2612 | int bb, changed, passes; | |
2613 | ||
2614 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2615 | sbitmap_copy (rd_out[bb] /*dst*/, rd_gen[bb] /*src*/); | |
2616 | ||
2617 | passes = 0; | |
2618 | changed = 1; | |
2619 | while (changed) | |
2620 | { | |
2621 | changed = 0; | |
2622 | for (bb = 0; bb < n_basic_blocks; bb++) | |
ac7c5af5 | 2623 | { |
7506f491 DE |
2624 | sbitmap_union_of_predecessors (reaching_defs[bb], rd_out, |
2625 | bb, s_preds); | |
2626 | changed |= sbitmap_union_of_diff (rd_out[bb], rd_gen[bb], | |
2627 | reaching_defs[bb], rd_kill[bb]); | |
ac7c5af5 | 2628 | } |
7506f491 DE |
2629 | passes++; |
2630 | } | |
2631 | ||
2632 | if (gcse_file) | |
2633 | fprintf (gcse_file, "reaching def computation: %d passes\n", passes); | |
2634 | } | |
2635 | \f | |
2636 | /* Classic GCSE available expression support. */ | |
2637 | ||
2638 | /* Allocate memory for available expression computation. */ | |
2639 | ||
2640 | static void | |
2641 | alloc_avail_expr_mem (n_blocks, n_exprs) | |
2642 | int n_blocks, n_exprs; | |
2643 | { | |
2644 | ae_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
2645 | sbitmap_vector_zero (ae_kill, n_basic_blocks); | |
2646 | ||
2647 | ae_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
2648 | sbitmap_vector_zero (ae_gen, n_basic_blocks); | |
2649 | ||
2650 | ae_in = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
2651 | sbitmap_vector_zero (ae_in, n_basic_blocks); | |
2652 | ||
2653 | ae_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
2654 | sbitmap_vector_zero (ae_out, n_basic_blocks); | |
2655 | ||
2656 | u_bitmap = (sbitmap) sbitmap_alloc (n_exprs); | |
2657 | sbitmap_ones (u_bitmap); | |
2658 | } | |
2659 | ||
2660 | static void | |
2661 | free_avail_expr_mem () | |
2662 | { | |
2663 | free (ae_kill); | |
2664 | free (ae_gen); | |
2665 | free (ae_in); | |
2666 | free (ae_out); | |
2667 | free (u_bitmap); | |
2668 | } | |
2669 | ||
2670 | /* Compute the set of available expressions generated in each basic block. */ | |
2671 | ||
2672 | static void | |
2673 | compute_ae_gen () | |
2674 | { | |
2675 | int i; | |
2676 | ||
2677 | /* For each recorded occurrence of each expression, set ae_gen[bb][expr]. | |
2678 | This is all we have to do because an expression is not recorded if it | |
2679 | is not available, and the only expressions we want to work with are the | |
2680 | ones that are recorded. */ | |
2681 | ||
2682 | for (i = 0; i < expr_hash_table_size; i++) | |
2683 | { | |
2684 | struct expr *expr = expr_hash_table[i]; | |
2685 | while (expr != NULL) | |
2686 | { | |
2687 | struct occr *occr = expr->avail_occr; | |
2688 | while (occr != NULL) | |
2689 | { | |
2690 | SET_BIT (ae_gen[BLOCK_NUM (occr->insn)], expr->bitmap_index); | |
2691 | occr = occr->next; | |
2692 | } | |
2693 | expr = expr->next_same_hash; | |
2694 | } | |
2695 | } | |
2696 | } | |
2697 | ||
2698 | /* Return non-zero if expression X is killed in BB. */ | |
2699 | ||
2700 | static int | |
2701 | expr_killed_p (x, bb) | |
2702 | rtx x; | |
2703 | int bb; | |
2704 | { | |
2705 | int i; | |
2706 | enum rtx_code code; | |
2707 | char *fmt; | |
2708 | ||
2709 | /* repeat is used to turn tail-recursion into iteration. */ | |
2710 | repeat: | |
2711 | ||
2712 | if (x == 0) | |
2713 | return 1; | |
2714 | ||
2715 | code = GET_CODE (x); | |
2716 | switch (code) | |
2717 | { | |
2718 | case REG: | |
2719 | return TEST_BIT (reg_set_in_block[bb], REGNO (x)); | |
2720 | ||
2721 | case MEM: | |
2722 | if (mem_set_in_block[bb]) | |
2723 | return 1; | |
2724 | x = XEXP (x, 0); | |
2725 | goto repeat; | |
2726 | ||
2727 | case PC: | |
2728 | case CC0: /*FIXME*/ | |
2729 | case CONST: | |
2730 | case CONST_INT: | |
2731 | case CONST_DOUBLE: | |
2732 | case SYMBOL_REF: | |
2733 | case LABEL_REF: | |
2734 | case ADDR_VEC: | |
2735 | case ADDR_DIFF_VEC: | |
2736 | return 0; | |
2737 | ||
2738 | default: | |
2739 | break; | |
2740 | } | |
2741 | ||
2742 | i = GET_RTX_LENGTH (code) - 1; | |
2743 | fmt = GET_RTX_FORMAT (code); | |
2744 | for (; i >= 0; i--) | |
2745 | { | |
2746 | if (fmt[i] == 'e') | |
2747 | { | |
2748 | rtx tem = XEXP (x, i); | |
2749 | ||
2750 | /* If we are about to do the last recursive call | |
2751 | needed at this level, change it into iteration. | |
2752 | This function is called enough to be worth it. */ | |
2753 | if (i == 0) | |
2754 | { | |
2755 | x = tem; | |
2756 | goto repeat; | |
2757 | } | |
2758 | if (expr_killed_p (tem, bb)) | |
2759 | return 1; | |
2760 | } | |
2761 | else if (fmt[i] == 'E') | |
2762 | { | |
2763 | int j; | |
2764 | for (j = 0; j < XVECLEN (x, i); j++) | |
2765 | { | |
2766 | if (expr_killed_p (XVECEXP (x, i, j), bb)) | |
2767 | return 1; | |
2768 | } | |
2769 | } | |
2770 | } | |
2771 | ||
2772 | return 0; | |
2773 | } | |
2774 | ||
2775 | /* Compute the set of available expressions killed in each basic block. */ | |
2776 | ||
2777 | static void | |
2778 | compute_ae_kill () | |
2779 | { | |
2780 | int bb,i; | |
2781 | ||
2782 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2783 | { | |
2784 | for (i = 0; i < expr_hash_table_size; i++) | |
2785 | { | |
2786 | struct expr *expr = expr_hash_table[i]; | |
2787 | ||
2788 | for ( ; expr != NULL; expr = expr->next_same_hash) | |
2789 | { | |
2790 | /* Skip EXPR if generated in this block. */ | |
2791 | if (TEST_BIT (ae_gen[bb], expr->bitmap_index)) | |
2792 | continue; | |
2793 | ||
2794 | if (expr_killed_p (expr->expr, bb)) | |
2795 | SET_BIT (ae_kill[bb], expr->bitmap_index); | |
2796 | } | |
2797 | } | |
2798 | } | |
2799 | } | |
2800 | ||
2801 | /* Compute available expressions. | |
2802 | ||
2803 | Implement the algorithm to find available expressions | |
2804 | as given in the Aho Sethi Ullman book, pages 627-631. */ | |
2805 | ||
2806 | static void | |
2807 | compute_available () | |
2808 | { | |
2809 | int bb, changed, passes; | |
2810 | ||
2811 | sbitmap_zero (ae_in[0]); | |
2812 | ||
2813 | sbitmap_copy (ae_out[0] /*dst*/, ae_gen[0] /*src*/); | |
2814 | ||
2815 | for (bb = 1; bb < n_basic_blocks; bb++) | |
2816 | sbitmap_difference (ae_out[bb], u_bitmap, ae_kill[bb]); | |
2817 | ||
2818 | passes = 0; | |
2819 | changed = 1; | |
2820 | while (changed) | |
2821 | { | |
2822 | changed = 0; | |
2823 | for (bb = 1; bb < n_basic_blocks; bb++) | |
2824 | { | |
b5ce41ff | 2825 | sbitmap_intersect_of_predecessors (ae_in[bb], ae_out, bb, s_preds); |
7506f491 DE |
2826 | changed |= sbitmap_union_of_diff (ae_out[bb], ae_gen[bb], |
2827 | ae_in[bb], ae_kill[bb]); | |
2828 | } | |
2829 | passes++; | |
2830 | } | |
2831 | ||
2832 | if (gcse_file) | |
2833 | fprintf (gcse_file, "avail expr computation: %d passes\n", passes); | |
2834 | } | |
2835 | \f | |
2836 | /* Actually perform the Classic GCSE optimizations. */ | |
2837 | ||
2838 | /* Return non-zero if occurrence OCCR of expression EXPR reaches block BB. | |
2839 | ||
2840 | CHECK_SELF_LOOP is non-zero if we should consider a block reaching itself | |
2841 | as a positive reach. We want to do this when there are two computations | |
2842 | of the expression in the block. | |
2843 | ||
2844 | VISITED is a pointer to a working buffer for tracking which BB's have | |
2845 | been visited. It is NULL for the top-level call. | |
2846 | ||
2847 | We treat reaching expressions that go through blocks containing the same | |
2848 | reaching expression as "not reaching". E.g. if EXPR is generated in blocks | |
2849 | 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block | |
2850 | 2 as not reaching. The intent is to improve the probability of finding | |
2851 | only one reaching expression and to reduce register lifetimes by picking | |
2852 | the closest such expression. */ | |
2853 | ||
2854 | static int | |
2855 | expr_reaches_here_p (occr, expr, bb, check_self_loop, visited) | |
2856 | struct occr *occr; | |
2857 | struct expr *expr; | |
2858 | int bb; | |
2859 | int check_self_loop; | |
2860 | char *visited; | |
2861 | { | |
2862 | int_list_ptr pred; | |
2863 | ||
2864 | if (visited == NULL) | |
2865 | { | |
2866 | visited = (char *) alloca (n_basic_blocks); | |
2867 | bzero (visited, n_basic_blocks); | |
2868 | } | |
2869 | ||
2870 | for (pred = s_preds[bb]; pred != NULL; pred = pred->next) | |
2871 | { | |
2872 | int pred_bb = INT_LIST_VAL (pred); | |
2873 | ||
2874 | if (visited[pred_bb]) | |
ac7c5af5 | 2875 | { |
7506f491 DE |
2876 | /* This predecessor has already been visited. |
2877 | Nothing to do. */ | |
2878 | ; | |
2879 | } | |
2880 | else if (pred_bb == bb) | |
ac7c5af5 | 2881 | { |
7506f491 DE |
2882 | /* BB loops on itself. */ |
2883 | if (check_self_loop | |
2884 | && TEST_BIT (ae_gen[pred_bb], expr->bitmap_index) | |
2885 | && BLOCK_NUM (occr->insn) == pred_bb) | |
2886 | return 1; | |
2887 | visited[pred_bb] = 1; | |
ac7c5af5 | 2888 | } |
7506f491 DE |
2889 | /* Ignore this predecessor if it kills the expression. */ |
2890 | else if (TEST_BIT (ae_kill[pred_bb], expr->bitmap_index)) | |
2891 | visited[pred_bb] = 1; | |
2892 | /* Does this predecessor generate this expression? */ | |
2893 | else if (TEST_BIT (ae_gen[pred_bb], expr->bitmap_index)) | |
2894 | { | |
2895 | /* Is this the occurrence we're looking for? | |
2896 | Note that there's only one generating occurrence per block | |
2897 | so we just need to check the block number. */ | |
2898 | if (BLOCK_NUM (occr->insn) == pred_bb) | |
2899 | return 1; | |
2900 | visited[pred_bb] = 1; | |
2901 | } | |
2902 | /* Neither gen nor kill. */ | |
2903 | else | |
ac7c5af5 | 2904 | { |
7506f491 DE |
2905 | visited[pred_bb] = 1; |
2906 | if (expr_reaches_here_p (occr, expr, pred_bb, check_self_loop, visited)) | |
2907 | return 1; | |
ac7c5af5 | 2908 | } |
7506f491 DE |
2909 | } |
2910 | ||
2911 | /* All paths have been checked. */ | |
2912 | return 0; | |
2913 | } | |
2914 | ||
2915 | /* Return the instruction that computes EXPR that reaches INSN's basic block. | |
2916 | If there is more than one such instruction, return NULL. | |
2917 | ||
2918 | Called only by handle_avail_expr. */ | |
2919 | ||
2920 | static rtx | |
2921 | computing_insn (expr, insn) | |
2922 | struct expr *expr; | |
2923 | rtx insn; | |
2924 | { | |
2925 | int bb = BLOCK_NUM (insn); | |
2926 | ||
2927 | if (expr->avail_occr->next == NULL) | |
2928 | { | |
2929 | if (BLOCK_NUM (expr->avail_occr->insn) == bb) | |
2930 | { | |
2931 | /* The available expression is actually itself | |
2932 | (i.e. a loop in the flow graph) so do nothing. */ | |
2933 | return NULL; | |
2934 | } | |
2935 | /* (FIXME) Case that we found a pattern that was created by | |
2936 | a substitution that took place. */ | |
2937 | return expr->avail_occr->insn; | |
2938 | } | |
2939 | else | |
2940 | { | |
2941 | /* Pattern is computed more than once. | |
2942 | Search backwards from this insn to see how many of these | |
2943 | computations actually reach this insn. */ | |
2944 | struct occr *occr; | |
2945 | rtx insn_computes_expr = NULL; | |
2946 | int can_reach = 0; | |
2947 | ||
2948 | for (occr = expr->avail_occr; occr != NULL; occr = occr->next) | |
2949 | { | |
2950 | if (BLOCK_NUM (occr->insn) == bb) | |
2951 | { | |
2952 | /* The expression is generated in this block. | |
2953 | The only time we care about this is when the expression | |
2954 | is generated later in the block [and thus there's a loop]. | |
2955 | We let the normal cse pass handle the other cases. */ | |
2956 | if (INSN_CUID (insn) < INSN_CUID (occr->insn)) | |
2957 | { | |
2958 | if (expr_reaches_here_p (occr, expr, bb, 1, NULL)) | |
2959 | { | |
2960 | can_reach++; | |
2961 | if (can_reach > 1) | |
2962 | return NULL; | |
2963 | insn_computes_expr = occr->insn; | |
2964 | } | |
2965 | } | |
2966 | } | |
2967 | else /* Computation of the pattern outside this block. */ | |
2968 | { | |
2969 | if (expr_reaches_here_p (occr, expr, bb, 0, NULL)) | |
2970 | { | |
2971 | can_reach++; | |
2972 | if (can_reach > 1) | |
2973 | return NULL; | |
2974 | insn_computes_expr = occr->insn; | |
2975 | } | |
2976 | } | |
2977 | } | |
2978 | ||
2979 | if (insn_computes_expr == NULL) | |
2980 | abort (); | |
2981 | return insn_computes_expr; | |
2982 | } | |
2983 | } | |
2984 | ||
2985 | /* Return non-zero if the definition in DEF_INSN can reach INSN. | |
2986 | Only called by can_disregard_other_sets. */ | |
2987 | ||
2988 | static int | |
2989 | def_reaches_here_p (insn, def_insn) | |
2990 | rtx insn, def_insn; | |
2991 | { | |
2992 | rtx reg; | |
2993 | ||
2994 | if (TEST_BIT (reaching_defs[BLOCK_NUM (insn)], INSN_CUID (def_insn))) | |
2995 | return 1; | |
2996 | ||
2997 | if (BLOCK_NUM (insn) == BLOCK_NUM (def_insn)) | |
2998 | { | |
2999 | if (INSN_CUID (def_insn) < INSN_CUID (insn)) | |
ac7c5af5 | 3000 | { |
7506f491 DE |
3001 | if (GET_CODE (PATTERN (def_insn)) == PARALLEL) |
3002 | return 1; | |
3003 | if (GET_CODE (PATTERN (def_insn)) == CLOBBER) | |
3004 | reg = XEXP (PATTERN (def_insn), 0); | |
3005 | else if (GET_CODE (PATTERN (def_insn)) == SET) | |
3006 | reg = SET_DEST (PATTERN (def_insn)); | |
3007 | else | |
3008 | abort (); | |
3009 | return ! reg_set_between_p (reg, NEXT_INSN (def_insn), insn); | |
3010 | } | |
3011 | else | |
3012 | return 0; | |
3013 | } | |
3014 | ||
3015 | return 0; | |
3016 | } | |
3017 | ||
3018 | /* Return non-zero if *ADDR_THIS_REG can only have one value at INSN. | |
3019 | The value returned is the number of definitions that reach INSN. | |
3020 | Returning a value of zero means that [maybe] more than one definition | |
3021 | reaches INSN and the caller can't perform whatever optimization it is | |
3022 | trying. i.e. it is always safe to return zero. */ | |
3023 | ||
3024 | static int | |
3025 | can_disregard_other_sets (addr_this_reg, insn, for_combine) | |
3026 | struct reg_set **addr_this_reg; | |
3027 | rtx insn; | |
3028 | int for_combine; | |
3029 | { | |
3030 | int number_of_reaching_defs = 0; | |
3031 | struct reg_set *this_reg = *addr_this_reg; | |
3032 | ||
3033 | while (this_reg) | |
3034 | { | |
3035 | if (def_reaches_here_p (insn, this_reg->insn)) | |
3036 | { | |
3037 | number_of_reaching_defs++; | |
3038 | /* Ignore parallels for now. */ | |
3039 | if (GET_CODE (PATTERN (this_reg->insn)) == PARALLEL) | |
3040 | return 0; | |
3041 | if (!for_combine | |
3042 | && (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER | |
3043 | || ! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)), | |
3044 | SET_SRC (PATTERN (insn))))) | |
3045 | { | |
3046 | /* A setting of the reg to a different value reaches INSN. */ | |
3047 | return 0; | |
3048 | } | |
3049 | if (number_of_reaching_defs > 1) | |
3050 | { | |
3051 | /* If in this setting the value the register is being | |
3052 | set to is equal to the previous value the register | |
3053 | was set to and this setting reaches the insn we are | |
3054 | trying to do the substitution on then we are ok. */ | |
3055 | ||
3056 | if (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER) | |
3057 | return 0; | |
3058 | if (! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)), | |
3059 | SET_SRC (PATTERN (insn)))) | |
3060 | return 0; | |
3061 | } | |
3062 | *addr_this_reg = this_reg; | |
3063 | } | |
3064 | ||
3065 | /* prev_this_reg = this_reg; */ | |
3066 | this_reg = this_reg->next; | |
3067 | } | |
3068 | ||
3069 | return number_of_reaching_defs; | |
3070 | } | |
3071 | ||
3072 | /* Expression computed by insn is available and the substitution is legal, | |
3073 | so try to perform the substitution. | |
3074 | ||
3075 | The result is non-zero if any changes were made. */ | |
3076 | ||
3077 | static int | |
3078 | handle_avail_expr (insn, expr) | |
3079 | rtx insn; | |
3080 | struct expr *expr; | |
3081 | { | |
3082 | rtx pat, insn_computes_expr; | |
3083 | rtx to; | |
3084 | struct reg_set *this_reg; | |
3085 | int found_setting, use_src; | |
3086 | int changed = 0; | |
3087 | ||
3088 | /* We only handle the case where one computation of the expression | |
3089 | reaches this instruction. */ | |
3090 | insn_computes_expr = computing_insn (expr, insn); | |
3091 | if (insn_computes_expr == NULL) | |
3092 | return 0; | |
3093 | ||
3094 | found_setting = 0; | |
3095 | use_src = 0; | |
3096 | ||
3097 | /* At this point we know only one computation of EXPR outside of this | |
3098 | block reaches this insn. Now try to find a register that the | |
3099 | expression is computed into. */ | |
3100 | ||
3101 | if (GET_CODE (SET_SRC (PATTERN (insn_computes_expr))) == REG) | |
3102 | { | |
3103 | /* This is the case when the available expression that reaches | |
3104 | here has already been handled as an available expression. */ | |
3105 | int regnum_for_replacing = REGNO (SET_SRC (PATTERN (insn_computes_expr))); | |
3106 | /* If the register was created by GCSE we can't use `reg_set_table', | |
3107 | however we know it's set only once. */ | |
3108 | if (regnum_for_replacing >= max_gcse_regno | |
3109 | /* If the register the expression is computed into is set only once, | |
3110 | or only one set reaches this insn, we can use it. */ | |
3111 | || (((this_reg = reg_set_table[regnum_for_replacing]), | |
3112 | this_reg->next == NULL) | |
3113 | || can_disregard_other_sets (&this_reg, insn, 0))) | |
3114 | { | |
3115 | use_src = 1; | |
3116 | found_setting = 1; | |
3117 | } | |
3118 | } | |
3119 | ||
3120 | if (!found_setting) | |
3121 | { | |
3122 | int regnum_for_replacing = REGNO (SET_DEST (PATTERN (insn_computes_expr))); | |
3123 | /* This shouldn't happen. */ | |
3124 | if (regnum_for_replacing >= max_gcse_regno) | |
3125 | abort (); | |
3126 | this_reg = reg_set_table[regnum_for_replacing]; | |
3127 | /* If the register the expression is computed into is set only once, | |
3128 | or only one set reaches this insn, use it. */ | |
3129 | if (this_reg->next == NULL | |
3130 | || can_disregard_other_sets (&this_reg, insn, 0)) | |
3131 | found_setting = 1; | |
3132 | } | |
3133 | ||
3134 | if (found_setting) | |
3135 | { | |
3136 | pat = PATTERN (insn); | |
3137 | if (use_src) | |
3138 | to = SET_SRC (PATTERN (insn_computes_expr)); | |
3139 | else | |
3140 | to = SET_DEST (PATTERN (insn_computes_expr)); | |
3141 | changed = validate_change (insn, &SET_SRC (pat), to, 0); | |
3142 | ||
3143 | /* We should be able to ignore the return code from validate_change but | |
3144 | to play it safe we check. */ | |
3145 | if (changed) | |
3146 | { | |
3147 | gcse_subst_count++; | |
3148 | if (gcse_file != NULL) | |
3149 | { | |
3150 | fprintf (gcse_file, "GCSE: Replacing the source in insn %d with reg %d %s insn %d\n", | |
3151 | INSN_UID (insn), REGNO (to), | |
3152 | use_src ? "from" : "set in", | |
3153 | INSN_UID (insn_computes_expr)); | |
3154 | } | |
3155 | ||
3156 | } | |
3157 | } | |
3158 | /* The register that the expr is computed into is set more than once. */ | |
3159 | else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/) | |
3160 | { | |
3161 | /* Insert an insn after insnx that copies the reg set in insnx | |
3162 | into a new pseudo register call this new register REGN. | |
3163 | From insnb until end of basic block or until REGB is set | |
3164 | replace all uses of REGB with REGN. */ | |
3165 | rtx new_insn; | |
3166 | ||
3167 | to = gen_reg_rtx (GET_MODE (SET_DEST (PATTERN (insn_computes_expr)))); | |
3168 | ||
3169 | /* Generate the new insn. */ | |
3170 | /* ??? If the change fails, we return 0, even though we created | |
3171 | an insn. I think this is ok. */ | |
9e6a5703 JC |
3172 | new_insn |
3173 | = emit_insn_after (gen_rtx_SET (VOIDmode, to, | |
3174 | SET_DEST (PATTERN (insn_computes_expr))), | |
7506f491 DE |
3175 | insn_computes_expr); |
3176 | /* Keep block number table up to date. */ | |
3177 | set_block_num (new_insn, BLOCK_NUM (insn_computes_expr)); | |
3178 | /* Keep register set table up to date. */ | |
3179 | record_one_set (REGNO (to), new_insn); | |
3180 | ||
3181 | gcse_create_count++; | |
3182 | if (gcse_file != NULL) | |
ac7c5af5 | 3183 | { |
7506f491 DE |
3184 | fprintf (gcse_file, "GCSE: Creating insn %d to copy value of reg %d, computed in insn %d,\n", |
3185 | INSN_UID (NEXT_INSN (insn_computes_expr)), | |
3186 | REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr)))), | |
3187 | INSN_UID (insn_computes_expr)); | |
3188 | fprintf (gcse_file, " into newly allocated reg %d\n", REGNO (to)); | |
ac7c5af5 | 3189 | } |
7506f491 DE |
3190 | |
3191 | pat = PATTERN (insn); | |
3192 | ||
3193 | /* Do register replacement for INSN. */ | |
3194 | changed = validate_change (insn, &SET_SRC (pat), | |
3195 | SET_DEST (PATTERN (NEXT_INSN (insn_computes_expr))), | |
3196 | 0); | |
3197 | ||
3198 | /* We should be able to ignore the return code from validate_change but | |
3199 | to play it safe we check. */ | |
3200 | if (changed) | |
3201 | { | |
3202 | gcse_subst_count++; | |
3203 | if (gcse_file != NULL) | |
3204 | { | |
3205 | fprintf (gcse_file, "GCSE: Replacing the source in insn %d with reg %d set in insn %d\n", | |
3206 | INSN_UID (insn), | |
3207 | REGNO (SET_DEST (PATTERN (NEXT_INSN (insn_computes_expr)))), | |
3208 | INSN_UID (insn_computes_expr)); | |
3209 | } | |
3210 | ||
3211 | } | |
3212 | } | |
3213 | ||
3214 | return changed; | |
3215 | } | |
3216 | ||
3217 | /* Perform classic GCSE. | |
3218 | This is called by one_classic_gcse_pass after all the dataflow analysis | |
3219 | has been done. | |
3220 | ||
3221 | The result is non-zero if a change was made. */ | |
3222 | ||
3223 | static int | |
3224 | classic_gcse () | |
3225 | { | |
3226 | int bb, changed; | |
3227 | rtx insn; | |
3228 | ||
3229 | /* Note we start at block 1. */ | |
3230 | ||
3231 | changed = 0; | |
3232 | for (bb = 1; bb < n_basic_blocks; bb++) | |
3233 | { | |
3234 | /* Reset tables used to keep track of what's still valid [since the | |
3235 | start of the block]. */ | |
3236 | reset_opr_set_tables (); | |
3237 | ||
3b413743 RH |
3238 | for (insn = BLOCK_HEAD (bb); |
3239 | insn != NULL && insn != NEXT_INSN (BLOCK_END (bb)); | |
7506f491 DE |
3240 | insn = NEXT_INSN (insn)) |
3241 | { | |
3242 | /* Is insn of form (set (pseudo-reg) ...)? */ | |
3243 | ||
3244 | if (GET_CODE (insn) == INSN | |
3245 | && GET_CODE (PATTERN (insn)) == SET | |
3246 | && GET_CODE (SET_DEST (PATTERN (insn))) == REG | |
3247 | && REGNO (SET_DEST (PATTERN (insn))) >= FIRST_PSEUDO_REGISTER) | |
3248 | { | |
3249 | rtx pat = PATTERN (insn); | |
3250 | rtx src = SET_SRC (pat); | |
3251 | struct expr *expr; | |
3252 | ||
3253 | if (want_to_gcse_p (src) | |
3254 | /* Is the expression recorded? */ | |
3255 | && ((expr = lookup_expr (src)) != NULL) | |
3256 | /* Is the expression available [at the start of the | |
3257 | block]? */ | |
3258 | && TEST_BIT (ae_in[bb], expr->bitmap_index) | |
3259 | /* Are the operands unchanged since the start of the | |
3260 | block? */ | |
3261 | && oprs_not_set_p (src, insn)) | |
3262 | changed |= handle_avail_expr (insn, expr); | |
3263 | } | |
3264 | ||
3265 | /* Keep track of everything modified by this insn. */ | |
3266 | /* ??? Need to be careful w.r.t. mods done to INSN. */ | |
3267 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
3268 | mark_oprs_set (insn); | |
ac7c5af5 | 3269 | } |
7506f491 DE |
3270 | } |
3271 | ||
3272 | return changed; | |
3273 | } | |
3274 | ||
3275 | /* Top level routine to perform one classic GCSE pass. | |
3276 | ||
3277 | Return non-zero if a change was made. */ | |
3278 | ||
3279 | static int | |
b5ce41ff | 3280 | one_classic_gcse_pass (pass) |
7506f491 DE |
3281 | int pass; |
3282 | { | |
3283 | int changed = 0; | |
3284 | ||
3285 | gcse_subst_count = 0; | |
3286 | gcse_create_count = 0; | |
3287 | ||
3288 | alloc_expr_hash_table (max_cuid); | |
3289 | alloc_rd_mem (n_basic_blocks, max_cuid); | |
b5ce41ff | 3290 | compute_expr_hash_table (); |
7506f491 DE |
3291 | if (gcse_file) |
3292 | dump_hash_table (gcse_file, "Expression", expr_hash_table, | |
3293 | expr_hash_table_size, n_exprs); | |
3294 | if (n_exprs > 0) | |
3295 | { | |
3296 | compute_kill_rd (); | |
3297 | compute_rd (); | |
3298 | alloc_avail_expr_mem (n_basic_blocks, n_exprs); | |
3299 | compute_ae_gen (); | |
3300 | compute_ae_kill (); | |
3301 | compute_available (); | |
3302 | changed = classic_gcse (); | |
3303 | free_avail_expr_mem (); | |
3304 | } | |
3305 | free_rd_mem (); | |
3306 | free_expr_hash_table (); | |
3307 | ||
3308 | if (gcse_file) | |
3309 | { | |
3310 | fprintf (gcse_file, "\n"); | |
3311 | fprintf (gcse_file, "GCSE of %s, pass %d: %d bytes needed, %d substs, %d insns created\n", | |
3312 | current_function_name, pass, | |
3313 | bytes_used, gcse_subst_count, gcse_create_count); | |
3314 | } | |
3315 | ||
3316 | return changed; | |
3317 | } | |
3318 | \f | |
3319 | /* Compute copy/constant propagation working variables. */ | |
3320 | ||
3321 | /* Local properties of assignments. */ | |
3322 | ||
3323 | static sbitmap *cprop_pavloc; | |
3324 | static sbitmap *cprop_absaltered; | |
3325 | ||
3326 | /* Global properties of assignments (computed from the local properties). */ | |
3327 | ||
3328 | static sbitmap *cprop_avin; | |
3329 | static sbitmap *cprop_avout; | |
3330 | ||
3331 | /* Allocate vars used for copy/const propagation. | |
3332 | N_BLOCKS is the number of basic blocks. | |
3333 | N_SETS is the number of sets. */ | |
3334 | ||
3335 | static void | |
3336 | alloc_cprop_mem (n_blocks, n_sets) | |
3337 | int n_blocks, n_sets; | |
3338 | { | |
3339 | cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets); | |
3340 | cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets); | |
3341 | ||
3342 | cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets); | |
3343 | cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets); | |
3344 | } | |
3345 | ||
3346 | /* Free vars used by copy/const propagation. */ | |
3347 | ||
3348 | static void | |
3349 | free_cprop_mem () | |
3350 | { | |
3351 | free (cprop_pavloc); | |
3352 | free (cprop_absaltered); | |
3353 | free (cprop_avin); | |
3354 | free (cprop_avout); | |
3355 | } | |
3356 | ||
7506f491 DE |
3357 | /* For each block, compute whether X is transparent. |
3358 | X is either an expression or an assignment [though we don't care which, | |
3359 | for this context an assignment is treated as an expression]. | |
3360 | For each block where an element of X is modified, set (SET_P == 1) or reset | |
3361 | (SET_P == 0) the INDX bit in BMAP. */ | |
3362 | ||
3363 | static void | |
3364 | compute_transp (x, indx, bmap, set_p) | |
3365 | rtx x; | |
3366 | int indx; | |
3367 | sbitmap *bmap; | |
3368 | int set_p; | |
3369 | { | |
3370 | int bb,i; | |
3371 | enum rtx_code code; | |
3372 | char *fmt; | |
3373 | ||
3374 | /* repeat is used to turn tail-recursion into iteration. */ | |
3375 | repeat: | |
3376 | ||
3377 | if (x == 0) | |
3378 | return; | |
3379 | ||
3380 | code = GET_CODE (x); | |
3381 | switch (code) | |
3382 | { | |
3383 | case REG: | |
3384 | { | |
3385 | reg_set *r; | |
3386 | int regno = REGNO (x); | |
3387 | ||
3388 | if (set_p) | |
3389 | { | |
3390 | if (regno < FIRST_PSEUDO_REGISTER) | |
3391 | { | |
3392 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3393 | if (TEST_BIT (reg_set_in_block[bb], regno)) | |
3394 | SET_BIT (bmap[bb], indx); | |
3395 | } | |
3396 | else | |
3397 | { | |
3398 | for (r = reg_set_table[regno]; r != NULL; r = r->next) | |
3399 | { | |
3400 | bb = BLOCK_NUM (r->insn); | |
3401 | SET_BIT (bmap[bb], indx); | |
3402 | } | |
3403 | } | |
3404 | } | |
3405 | else | |
3406 | { | |
3407 | if (regno < FIRST_PSEUDO_REGISTER) | |
3408 | { | |
3409 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3410 | if (TEST_BIT (reg_set_in_block[bb], regno)) | |
3411 | RESET_BIT (bmap[bb], indx); | |
3412 | } | |
3413 | else | |
3414 | { | |
3415 | for (r = reg_set_table[regno]; r != NULL; r = r->next) | |
3416 | { | |
3417 | bb = BLOCK_NUM (r->insn); | |
3418 | RESET_BIT (bmap[bb], indx); | |
3419 | } | |
3420 | } | |
3421 | } | |
3422 | return; | |
3423 | } | |
3424 | ||
3425 | case MEM: | |
3426 | if (set_p) | |
3427 | { | |
3428 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3429 | if (mem_set_in_block[bb]) | |
3430 | SET_BIT (bmap[bb], indx); | |
3431 | } | |
3432 | else | |
3433 | { | |
3434 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3435 | if (mem_set_in_block[bb]) | |
3436 | RESET_BIT (bmap[bb], indx); | |
3437 | } | |
3438 | x = XEXP (x, 0); | |
3439 | goto repeat; | |
3440 | ||
3441 | case PC: | |
3442 | case CC0: /*FIXME*/ | |
3443 | case CONST: | |
3444 | case CONST_INT: | |
3445 | case CONST_DOUBLE: | |
3446 | case SYMBOL_REF: | |
3447 | case LABEL_REF: | |
3448 | case ADDR_VEC: | |
3449 | case ADDR_DIFF_VEC: | |
3450 | return; | |
3451 | ||
3452 | default: | |
3453 | break; | |
3454 | } | |
3455 | ||
3456 | i = GET_RTX_LENGTH (code) - 1; | |
3457 | fmt = GET_RTX_FORMAT (code); | |
3458 | for (; i >= 0; i--) | |
3459 | { | |
3460 | if (fmt[i] == 'e') | |
3461 | { | |
3462 | rtx tem = XEXP (x, i); | |
3463 | ||
3464 | /* If we are about to do the last recursive call | |
3465 | needed at this level, change it into iteration. | |
3466 | This function is called enough to be worth it. */ | |
3467 | if (i == 0) | |
3468 | { | |
3469 | x = tem; | |
3470 | goto repeat; | |
3471 | } | |
3472 | compute_transp (tem, indx, bmap, set_p); | |
3473 | } | |
3474 | else if (fmt[i] == 'E') | |
3475 | { | |
3476 | int j; | |
3477 | for (j = 0; j < XVECLEN (x, i); j++) | |
3478 | compute_transp (XVECEXP (x, i, j), indx, bmap, set_p); | |
3479 | } | |
3480 | } | |
3481 | } | |
3482 | ||
b5ce41ff JL |
3483 | /* Compute the available expressions at the start and end of each |
3484 | basic block for cprop. This particular dataflow equation is | |
3485 | used often enough that we might want to generalize it and make | |
3486 | as a subroutine for other global optimizations that need available | |
3487 | in/out information. */ | |
7506f491 DE |
3488 | static void |
3489 | compute_cprop_avinout () | |
3490 | { | |
3491 | int bb, changed, passes; | |
3492 | ||
3493 | sbitmap_zero (cprop_avin[0]); | |
3494 | sbitmap_vector_ones (cprop_avout, n_basic_blocks); | |
3495 | ||
3496 | passes = 0; | |
3497 | changed = 1; | |
3498 | while (changed) | |
3499 | { | |
3500 | changed = 0; | |
3501 | for (bb = 0; bb < n_basic_blocks; bb++) | |
ac7c5af5 | 3502 | { |
7506f491 | 3503 | if (bb != 0) |
b5ce41ff JL |
3504 | sbitmap_intersect_of_predecessors (cprop_avin[bb], |
3505 | cprop_avout, bb, s_preds); | |
7506f491 DE |
3506 | changed |= sbitmap_union_of_diff (cprop_avout[bb], |
3507 | cprop_pavloc[bb], | |
3508 | cprop_avin[bb], | |
3509 | cprop_absaltered[bb]); | |
3510 | } | |
3511 | passes++; | |
3512 | } | |
3513 | ||
3514 | if (gcse_file) | |
3515 | fprintf (gcse_file, "cprop avail expr computation: %d passes\n", passes); | |
3516 | } | |
3517 | ||
3518 | /* Top level routine to do the dataflow analysis needed by copy/const | |
3519 | propagation. */ | |
3520 | ||
3521 | static void | |
3522 | compute_cprop_data () | |
3523 | { | |
b5ce41ff | 3524 | compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, 1); |
7506f491 DE |
3525 | compute_cprop_avinout (); |
3526 | } | |
3527 | \f | |
3528 | /* Copy/constant propagation. */ | |
3529 | ||
3530 | struct reg_use { | |
3531 | rtx reg_rtx; | |
3532 | }; | |
3533 | ||
3534 | /* Maximum number of register uses in an insn that we handle. */ | |
3535 | #define MAX_USES 8 | |
3536 | ||
3537 | /* Table of uses found in an insn. | |
3538 | Allocated statically to avoid alloc/free complexity and overhead. */ | |
3539 | static struct reg_use reg_use_table[MAX_USES]; | |
3540 | ||
3541 | /* Index into `reg_use_table' while building it. */ | |
3542 | static int reg_use_count; | |
3543 | ||
3544 | /* Set up a list of register numbers used in INSN. | |
3545 | The found uses are stored in `reg_use_table'. | |
3546 | `reg_use_count' is initialized to zero before entry, and | |
3547 | contains the number of uses in the table upon exit. | |
3548 | ||
3549 | ??? If a register appears multiple times we will record it multiple | |
3550 | times. This doesn't hurt anything but it will slow things down. */ | |
3551 | ||
3552 | static void | |
3553 | find_used_regs (x) | |
3554 | rtx x; | |
3555 | { | |
3556 | int i; | |
3557 | enum rtx_code code; | |
3558 | char *fmt; | |
3559 | ||
3560 | /* repeat is used to turn tail-recursion into iteration. */ | |
3561 | repeat: | |
3562 | ||
3563 | if (x == 0) | |
3564 | return; | |
3565 | ||
3566 | code = GET_CODE (x); | |
3567 | switch (code) | |
3568 | { | |
3569 | case REG: | |
3570 | if (reg_use_count == MAX_USES) | |
3571 | return; | |
3572 | reg_use_table[reg_use_count].reg_rtx = x; | |
3573 | reg_use_count++; | |
3574 | return; | |
3575 | ||
3576 | case MEM: | |
3577 | x = XEXP (x, 0); | |
3578 | goto repeat; | |
3579 | ||
3580 | case PC: | |
3581 | case CC0: | |
3582 | case CONST: | |
3583 | case CONST_INT: | |
3584 | case CONST_DOUBLE: | |
3585 | case SYMBOL_REF: | |
3586 | case LABEL_REF: | |
3587 | case CLOBBER: | |
3588 | case ADDR_VEC: | |
3589 | case ADDR_DIFF_VEC: | |
3590 | case ASM_INPUT: /*FIXME*/ | |
3591 | return; | |
3592 | ||
3593 | case SET: | |
3594 | if (GET_CODE (SET_DEST (x)) == MEM) | |
3595 | find_used_regs (SET_DEST (x)); | |
3596 | x = SET_SRC (x); | |
3597 | goto repeat; | |
3598 | ||
3599 | default: | |
3600 | break; | |
3601 | } | |
3602 | ||
3603 | /* Recursively scan the operands of this expression. */ | |
3604 | ||
3605 | fmt = GET_RTX_FORMAT (code); | |
3606 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
3607 | { | |
3608 | if (fmt[i] == 'e') | |
3609 | { | |
3610 | /* If we are about to do the last recursive call | |
3611 | needed at this level, change it into iteration. | |
3612 | This function is called enough to be worth it. */ | |
3613 | if (i == 0) | |
3614 | { | |
3615 | x = XEXP (x, 0); | |
3616 | goto repeat; | |
3617 | } | |
3618 | find_used_regs (XEXP (x, i)); | |
3619 | } | |
3620 | else if (fmt[i] == 'E') | |
3621 | { | |
3622 | int j; | |
3623 | for (j = 0; j < XVECLEN (x, i); j++) | |
3624 | find_used_regs (XVECEXP (x, i, j)); | |
3625 | } | |
3626 | } | |
3627 | } | |
3628 | ||
3629 | /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO. | |
3630 | Returns non-zero is successful. */ | |
3631 | ||
3632 | static int | |
3633 | try_replace_reg (from, to, insn) | |
3634 | rtx from, to, insn; | |
3635 | { | |
e78d9500 JL |
3636 | /* If this fails we could try to simplify the result of the |
3637 | replacement and attempt to recognize the simplified insn. | |
3638 | ||
3639 | But we need a general simplify_rtx that doesn't have pass | |
3640 | specific state variables. I'm not aware of one at the moment. */ | |
7506f491 DE |
3641 | return validate_replace_src (from, to, insn); |
3642 | } | |
3643 | ||
3644 | /* Find a set of REGNO that is available on entry to INSN's block. | |
3645 | Returns NULL if not found. */ | |
3646 | ||
3647 | static struct expr * | |
3648 | find_avail_set (regno, insn) | |
3649 | int regno; | |
3650 | rtx insn; | |
3651 | { | |
3652 | struct expr *set = lookup_set (regno, NULL_RTX); | |
3653 | ||
3654 | while (set) | |
3655 | { | |
3656 | if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index)) | |
3657 | break; | |
3658 | set = next_set (regno, set); | |
3659 | } | |
3660 | ||
3661 | return set; | |
3662 | } | |
3663 | ||
3664 | /* Perform constant and copy propagation on INSN. | |
3665 | The result is non-zero if a change was made. */ | |
3666 | ||
3667 | static int | |
b5ce41ff | 3668 | cprop_insn (insn, alter_jumps) |
7506f491 | 3669 | rtx insn; |
b5ce41ff | 3670 | int alter_jumps; |
7506f491 DE |
3671 | { |
3672 | struct reg_use *reg_used; | |
3673 | int changed = 0; | |
3674 | ||
e78d9500 JL |
3675 | /* Only propagate into SETs. Note that a conditional jump is a |
3676 | SET with pc_rtx as the destination. */ | |
3677 | if ((GET_CODE (insn) != INSN | |
3678 | && GET_CODE (insn) != JUMP_INSN) | |
7506f491 DE |
3679 | || GET_CODE (PATTERN (insn)) != SET) |
3680 | return 0; | |
3681 | ||
3682 | reg_use_count = 0; | |
3683 | find_used_regs (PATTERN (insn)); | |
3684 | ||
3685 | reg_used = ®_use_table[0]; | |
3686 | for ( ; reg_use_count > 0; reg_used++, reg_use_count--) | |
3687 | { | |
3688 | rtx pat, src; | |
3689 | struct expr *set; | |
3690 | int regno = REGNO (reg_used->reg_rtx); | |
3691 | ||
3692 | /* Ignore registers created by GCSE. | |
3693 | We do this because ... */ | |
3694 | if (regno >= max_gcse_regno) | |
3695 | continue; | |
3696 | ||
3697 | /* If the register has already been set in this block, there's | |
3698 | nothing we can do. */ | |
3699 | if (! oprs_not_set_p (reg_used->reg_rtx, insn)) | |
3700 | continue; | |
3701 | ||
3702 | /* Find an assignment that sets reg_used and is available | |
3703 | at the start of the block. */ | |
3704 | set = find_avail_set (regno, insn); | |
3705 | if (! set) | |
3706 | continue; | |
3707 | ||
3708 | pat = set->expr; | |
3709 | /* ??? We might be able to handle PARALLELs. Later. */ | |
3710 | if (GET_CODE (pat) != SET) | |
3711 | abort (); | |
3712 | src = SET_SRC (pat); | |
3713 | ||
e78d9500 JL |
3714 | /* Constant propagation. */ |
3715 | if (GET_CODE (src) == CONST_INT || GET_CODE (src) == CONST_DOUBLE) | |
7506f491 | 3716 | { |
e78d9500 JL |
3717 | /* Handle normal insns first. */ |
3718 | if (GET_CODE (insn) == INSN | |
3719 | && try_replace_reg (reg_used->reg_rtx, src, insn)) | |
7506f491 DE |
3720 | { |
3721 | changed = 1; | |
3722 | const_prop_count++; | |
3723 | if (gcse_file != NULL) | |
3724 | { | |
3725 | fprintf (gcse_file, "CONST-PROP: Replacing reg %d in insn %d with constant ", | |
3726 | regno, INSN_UID (insn)); | |
e78d9500 | 3727 | print_rtl (gcse_file, src); |
7506f491 DE |
3728 | fprintf (gcse_file, "\n"); |
3729 | } | |
3730 | ||
3731 | /* The original insn setting reg_used may or may not now be | |
3732 | deletable. We leave the deletion to flow. */ | |
3733 | } | |
e78d9500 JL |
3734 | |
3735 | /* Try to propagate a CONST_INT into a conditional jump. | |
3736 | We're pretty specific about what we will handle in this | |
3737 | code, we can extend this as necessary over time. | |
3738 | ||
3739 | Right now the insn in question must look like | |
3740 | ||
3741 | (set (pc) (if_then_else ...)) | |
3742 | ||
3743 | Note this does not currently handle machines which use cc0. */ | |
b5ce41ff JL |
3744 | else if (alter_jumps |
3745 | && GET_CODE (insn) == JUMP_INSN && condjump_p (insn)) | |
e78d9500 JL |
3746 | { |
3747 | /* We want a copy of the JUMP_INSN so we can modify it | |
3748 | in-place as needed without effecting the original. */ | |
3749 | rtx copy = copy_rtx (insn); | |
3750 | rtx set = PATTERN (copy); | |
3751 | rtx temp; | |
3752 | ||
3753 | /* Replace the register with the appropriate constant. */ | |
3754 | replace_rtx (SET_SRC (set), reg_used->reg_rtx, src); | |
3755 | ||
3756 | temp = simplify_ternary_operation (GET_CODE (SET_SRC (set)), | |
3757 | GET_MODE (SET_SRC (set)), | |
3758 | GET_MODE (XEXP (SET_SRC (set), 0)), | |
3759 | XEXP (SET_SRC (set), 0), | |
3760 | XEXP (SET_SRC (set), 1), | |
3761 | XEXP (SET_SRC (set), 2)); | |
3762 | ||
3763 | /* If no simplification can be made, then try the next | |
3764 | register. */ | |
3765 | if (temp) | |
3766 | SET_SRC (set) = temp; | |
3767 | else | |
3768 | continue; | |
3769 | ||
3770 | /* That may have changed the structure of TEMP, so | |
3771 | force it to be rerecognized if it has not turned | |
3772 | into a nop or unconditional jump. */ | |
3773 | ||
3774 | INSN_CODE (copy) = -1; | |
3775 | if ((SET_DEST (set) == pc_rtx | |
3776 | && (SET_SRC (set) == pc_rtx | |
3777 | || GET_CODE (SET_SRC (set)) == LABEL_REF)) | |
3778 | || recog (PATTERN (copy), copy, NULL) >= 0) | |
3779 | { | |
3780 | /* This has either become an unconditional jump | |
3781 | or a nop-jump. We'd like to delete nop jumps | |
3782 | here, but doing so confuses gcse. So we just | |
3783 | make the replacement and let later passes | |
3784 | sort things out. */ | |
3785 | PATTERN (insn) = set; | |
3786 | INSN_CODE (insn) = -1; | |
3787 | ||
3788 | /* One less use of the label this insn used to jump to | |
3789 | if we turned this into a NOP jump. */ | |
3790 | if (SET_SRC (set) == pc_rtx && JUMP_LABEL (insn) != 0) | |
3791 | --LABEL_NUSES (JUMP_LABEL (insn)); | |
3792 | ||
3793 | /* If this has turned into an unconditional jump, | |
3794 | then put a barrier after it so that the unreachable | |
3795 | code will be deleted. */ | |
3796 | if (GET_CODE (SET_SRC (set)) == LABEL_REF) | |
3797 | emit_barrier_after (insn); | |
3798 | ||
3799 | run_jump_opt_after_gcse = 1; | |
3800 | ||
3801 | changed = 1; | |
3802 | const_prop_count++; | |
3803 | if (gcse_file != NULL) | |
3804 | { | |
3805 | fprintf (gcse_file, "CONST-PROP: Replacing reg %d in insn %d with constant ", | |
3806 | regno, INSN_UID (insn)); | |
3807 | print_rtl (gcse_file, src); | |
3808 | fprintf (gcse_file, "\n"); | |
3809 | } | |
3810 | } | |
3811 | } | |
7506f491 DE |
3812 | } |
3813 | else if (GET_CODE (src) == REG | |
3814 | && REGNO (src) >= FIRST_PSEUDO_REGISTER | |
3815 | && REGNO (src) != regno) | |
3816 | { | |
3817 | /* We know the set is available. | |
3818 | Now check that SET_SRC is ANTLOC (i.e. none of the source operands | |
3819 | have changed since the start of the block). */ | |
3820 | if (oprs_not_set_p (src, insn)) | |
3821 | { | |
3822 | if (try_replace_reg (reg_used->reg_rtx, src, insn)) | |
3823 | { | |
3824 | changed = 1; | |
3825 | copy_prop_count++; | |
3826 | if (gcse_file != NULL) | |
3827 | { | |
3828 | fprintf (gcse_file, "COPY-PROP: Replacing reg %d in insn %d with reg %d\n", | |
3829 | regno, INSN_UID (insn), REGNO (src)); | |
3830 | } | |
3831 | ||
3832 | /* The original insn setting reg_used may or may not now be | |
3833 | deletable. We leave the deletion to flow. */ | |
3834 | /* FIXME: If it turns out that the insn isn't deletable, | |
3835 | then we may have unnecessarily extended register lifetimes | |
3836 | and made things worse. */ | |
3837 | } | |
3838 | } | |
3839 | } | |
3840 | } | |
3841 | ||
3842 | return changed; | |
3843 | } | |
3844 | ||
3845 | /* Forward propagate copies. | |
3846 | This includes copies and constants. | |
3847 | Return non-zero if a change was made. */ | |
3848 | ||
3849 | static int | |
b5ce41ff JL |
3850 | cprop (alter_jumps) |
3851 | int alter_jumps; | |
7506f491 DE |
3852 | { |
3853 | int bb, changed; | |
3854 | rtx insn; | |
3855 | ||
3856 | /* Note we start at block 1. */ | |
3857 | ||
3858 | changed = 0; | |
3859 | for (bb = 1; bb < n_basic_blocks; bb++) | |
3860 | { | |
3861 | /* Reset tables used to keep track of what's still valid [since the | |
3862 | start of the block]. */ | |
3863 | reset_opr_set_tables (); | |
3864 | ||
3b413743 RH |
3865 | for (insn = BLOCK_HEAD (bb); |
3866 | insn != NULL && insn != NEXT_INSN (BLOCK_END (bb)); | |
7506f491 DE |
3867 | insn = NEXT_INSN (insn)) |
3868 | { | |
3869 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
3870 | { | |
b5ce41ff | 3871 | changed |= cprop_insn (insn, alter_jumps); |
7506f491 DE |
3872 | |
3873 | /* Keep track of everything modified by this insn. */ | |
3874 | /* ??? Need to be careful w.r.t. mods done to INSN. */ | |
3875 | mark_oprs_set (insn); | |
3876 | } | |
ac7c5af5 | 3877 | } |
7506f491 DE |
3878 | } |
3879 | ||
3880 | if (gcse_file != NULL) | |
3881 | fprintf (gcse_file, "\n"); | |
3882 | ||
3883 | return changed; | |
3884 | } | |
3885 | ||
3886 | /* Perform one copy/constant propagation pass. | |
3887 | F is the first insn in the function. | |
3888 | PASS is the pass count. */ | |
3889 | ||
3890 | static int | |
b5ce41ff | 3891 | one_cprop_pass (pass, alter_jumps) |
7506f491 | 3892 | int pass; |
b5ce41ff | 3893 | int alter_jumps; |
7506f491 DE |
3894 | { |
3895 | int changed = 0; | |
3896 | ||
3897 | const_prop_count = 0; | |
3898 | copy_prop_count = 0; | |
3899 | ||
3900 | alloc_set_hash_table (max_cuid); | |
b5ce41ff | 3901 | compute_set_hash_table (); |
7506f491 DE |
3902 | if (gcse_file) |
3903 | dump_hash_table (gcse_file, "SET", set_hash_table, set_hash_table_size, | |
3904 | n_sets); | |
3905 | if (n_sets > 0) | |
3906 | { | |
3907 | alloc_cprop_mem (n_basic_blocks, n_sets); | |
3908 | compute_cprop_data (); | |
b5ce41ff | 3909 | changed = cprop (alter_jumps); |
7506f491 DE |
3910 | free_cprop_mem (); |
3911 | } | |
3912 | free_set_hash_table (); | |
3913 | ||
3914 | if (gcse_file) | |
3915 | { | |
3916 | fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, %d const props, %d copy props\n", | |
3917 | current_function_name, pass, | |
3918 | bytes_used, const_prop_count, copy_prop_count); | |
3919 | fprintf (gcse_file, "\n"); | |
3920 | } | |
3921 | ||
3922 | return changed; | |
3923 | } | |
3924 | \f | |
a65f3558 | 3925 | /* Compute PRE+LCM working variables. */ |
7506f491 DE |
3926 | |
3927 | /* Local properties of expressions. */ | |
3928 | /* Nonzero for expressions that are transparent in the block. */ | |
a65f3558 | 3929 | static sbitmap *transp; |
7506f491 | 3930 | |
5c35539b RH |
3931 | /* Nonzero for expressions that are transparent at the end of the block. |
3932 | This is only zero for expressions killed by abnormal critical edge | |
3933 | created by a calls. */ | |
a65f3558 | 3934 | static sbitmap *transpout; |
5c35539b | 3935 | |
a65f3558 JL |
3936 | /* Nonzero for expressions that are computed (available) in the block. */ |
3937 | static sbitmap *comp; | |
7506f491 | 3938 | |
a65f3558 JL |
3939 | /* Nonzero for expressions that are locally anticipatable in the block. */ |
3940 | static sbitmap *antloc; | |
7506f491 | 3941 | |
a65f3558 JL |
3942 | /* Nonzero for expressions where this block is an optimal computation |
3943 | point. */ | |
3944 | static sbitmap *pre_optimal; | |
5c35539b | 3945 | |
a65f3558 JL |
3946 | /* Nonzero for expressions which are redundant in a particular block. */ |
3947 | static sbitmap *pre_redundant; | |
7506f491 | 3948 | |
a65f3558 | 3949 | static sbitmap *temp_bitmap; |
7506f491 | 3950 | |
a65f3558 JL |
3951 | /* Redundant insns. */ |
3952 | static sbitmap pre_redundant_insns; | |
7506f491 | 3953 | |
a65f3558 | 3954 | /* Allocate vars used for PRE analysis. */ |
7506f491 DE |
3955 | |
3956 | static void | |
a65f3558 JL |
3957 | alloc_pre_mem (n_blocks, n_exprs) |
3958 | int n_blocks, n_exprs; | |
7506f491 | 3959 | { |
a65f3558 JL |
3960 | transp = sbitmap_vector_alloc (n_blocks, n_exprs); |
3961 | comp = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3962 | antloc = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3963 | ||
3964 | temp_bitmap = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3965 | pre_optimal = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3966 | pre_redundant = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3967 | transpout = sbitmap_vector_alloc (n_blocks, n_exprs); | |
7506f491 DE |
3968 | } |
3969 | ||
a65f3558 | 3970 | /* Free vars used for PRE analysis. */ |
7506f491 DE |
3971 | |
3972 | static void | |
a65f3558 | 3973 | free_pre_mem () |
7506f491 | 3974 | { |
a65f3558 JL |
3975 | free (transp); |
3976 | free (comp); | |
3977 | free (antloc); | |
7506f491 | 3978 | |
a65f3558 JL |
3979 | free (pre_optimal); |
3980 | free (pre_redundant); | |
3981 | free (transpout); | |
7506f491 DE |
3982 | } |
3983 | ||
3984 | /* Top level routine to do the dataflow analysis needed by PRE. */ | |
3985 | ||
3986 | static void | |
3987 | compute_pre_data () | |
3988 | { | |
a65f3558 JL |
3989 | compute_local_properties (transp, comp, antloc, 0); |
3990 | compute_transpout (); | |
3991 | pre_lcm (n_basic_blocks, n_exprs, s_preds, s_succs, transp, | |
3992 | antloc, pre_redundant, pre_optimal); | |
7506f491 | 3993 | } |
a65f3558 | 3994 | |
7506f491 DE |
3995 | \f |
3996 | /* PRE utilities */ | |
3997 | ||
a65f3558 JL |
3998 | /* Return non-zero if an occurrence of expression EXPR in OCCR_BB would reach |
3999 | block BB. | |
7506f491 DE |
4000 | |
4001 | VISITED is a pointer to a working buffer for tracking which BB's have | |
4002 | been visited. It is NULL for the top-level call. | |
4003 | ||
a65f3558 JL |
4004 | CHECK_PRE_COMP controls whether or not we check for a computation of |
4005 | EXPR in OCCR_BB. | |
4006 | ||
7506f491 DE |
4007 | We treat reaching expressions that go through blocks containing the same |
4008 | reaching expression as "not reaching". E.g. if EXPR is generated in blocks | |
4009 | 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block | |
4010 | 2 as not reaching. The intent is to improve the probability of finding | |
4011 | only one reaching expression and to reduce register lifetimes by picking | |
4012 | the closest such expression. */ | |
4013 | ||
4014 | static int | |
a65f3558 JL |
4015 | pre_expr_reaches_here_p (occr_bb, expr, bb, check_pre_comp, visited) |
4016 | int occr_bb; | |
7506f491 DE |
4017 | struct expr *expr; |
4018 | int bb; | |
a65f3558 | 4019 | int check_pre_comp; |
7506f491 DE |
4020 | char *visited; |
4021 | { | |
4022 | int_list_ptr pred; | |
4023 | ||
4024 | if (visited == NULL) | |
4025 | { | |
4026 | visited = (char *) alloca (n_basic_blocks); | |
4027 | bzero (visited, n_basic_blocks); | |
4028 | } | |
4029 | ||
4030 | for (pred = s_preds[bb]; pred != NULL; pred = pred->next) | |
4031 | { | |
4032 | int pred_bb = INT_LIST_VAL (pred); | |
4033 | ||
4034 | if (pred_bb == ENTRY_BLOCK | |
4035 | /* Has predecessor has already been visited? */ | |
4036 | || visited[pred_bb]) | |
ac7c5af5 | 4037 | { |
7506f491 DE |
4038 | /* Nothing to do. */ |
4039 | } | |
4040 | /* Does this predecessor generate this expression? */ | |
a65f3558 JL |
4041 | else if ((!check_pre_comp && occr_bb == pred_bb) |
4042 | || TEST_BIT (comp[pred_bb], expr->bitmap_index)) | |
7506f491 DE |
4043 | { |
4044 | /* Is this the occurrence we're looking for? | |
4045 | Note that there's only one generating occurrence per block | |
4046 | so we just need to check the block number. */ | |
a65f3558 | 4047 | if (occr_bb == pred_bb) |
7506f491 DE |
4048 | return 1; |
4049 | visited[pred_bb] = 1; | |
4050 | } | |
4051 | /* Ignore this predecessor if it kills the expression. */ | |
a65f3558 | 4052 | else if (! TEST_BIT (transp[pred_bb], expr->bitmap_index)) |
7506f491 DE |
4053 | visited[pred_bb] = 1; |
4054 | /* Neither gen nor kill. */ | |
4055 | else | |
ac7c5af5 | 4056 | { |
7506f491 | 4057 | visited[pred_bb] = 1; |
a65f3558 JL |
4058 | if (pre_expr_reaches_here_p (occr_bb, expr, pred_bb, |
4059 | check_pre_comp, visited)) | |
7506f491 | 4060 | return 1; |
ac7c5af5 | 4061 | } |
7506f491 DE |
4062 | } |
4063 | ||
4064 | /* All paths have been checked. */ | |
4065 | return 0; | |
4066 | } | |
4067 | \f | |
a65f3558 JL |
4068 | /* Add EXPR to the end of basic block BB. |
4069 | ||
4070 | This is used by both the PRE and code hoisting. | |
4071 | ||
4072 | For PRE, we want to verify that the expr is either transparent | |
4073 | or locally anticipatable in the target block. This check makes | |
4074 | no sense for code hoisting. */ | |
7506f491 DE |
4075 | |
4076 | static void | |
a65f3558 | 4077 | insert_insn_end_bb (expr, bb, pre) |
7506f491 DE |
4078 | struct expr *expr; |
4079 | int bb; | |
a65f3558 | 4080 | int pre; |
7506f491 DE |
4081 | { |
4082 | rtx insn = BLOCK_END (bb); | |
4083 | rtx new_insn; | |
4084 | rtx reg = expr->reaching_reg; | |
4085 | int regno = REGNO (reg); | |
a65f3558 JL |
4086 | rtx pat, copied_expr; |
4087 | rtx first_new_insn; | |
7506f491 | 4088 | |
a65f3558 JL |
4089 | start_sequence (); |
4090 | copied_expr = copy_rtx (expr->expr); | |
4091 | emit_move_insn (reg, copied_expr); | |
4092 | first_new_insn = get_insns (); | |
4093 | pat = gen_sequence (); | |
4094 | end_sequence (); | |
7506f491 DE |
4095 | |
4096 | /* If the last insn is a jump, insert EXPR in front [taking care to | |
4097 | handle cc0, etc. properly]. */ | |
4098 | ||
4099 | if (GET_CODE (insn) == JUMP_INSN) | |
4100 | { | |
50b2596f | 4101 | #ifdef HAVE_cc0 |
7506f491 | 4102 | rtx note; |
50b2596f | 4103 | #endif |
7506f491 DE |
4104 | |
4105 | /* If this is a jump table, then we can't insert stuff here. Since | |
4106 | we know the previous real insn must be the tablejump, we insert | |
4107 | the new instruction just before the tablejump. */ | |
4108 | if (GET_CODE (PATTERN (insn)) == ADDR_VEC | |
4109 | || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) | |
4110 | insn = prev_real_insn (insn); | |
4111 | ||
4112 | #ifdef HAVE_cc0 | |
4113 | /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts | |
4114 | if cc0 isn't set. */ | |
4115 | note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX); | |
4116 | if (note) | |
4117 | insn = XEXP (note, 0); | |
4118 | else | |
4119 | { | |
4120 | rtx maybe_cc0_setter = prev_nonnote_insn (insn); | |
4121 | if (maybe_cc0_setter | |
4122 | && GET_RTX_CLASS (GET_CODE (maybe_cc0_setter)) == 'i' | |
4123 | && sets_cc0_p (PATTERN (maybe_cc0_setter))) | |
4124 | insn = maybe_cc0_setter; | |
4125 | } | |
4126 | #endif | |
4127 | /* FIXME: What if something in cc0/jump uses value set in new insn? */ | |
4128 | new_insn = emit_insn_before (pat, insn); | |
4129 | if (BLOCK_HEAD (bb) == insn) | |
4130 | BLOCK_HEAD (bb) = new_insn; | |
3947e2f9 RH |
4131 | } |
4132 | /* Likewise if the last insn is a call, as will happen in the presence | |
4133 | of exception handling. */ | |
5c35539b | 4134 | else if (GET_CODE (insn) == CALL_INSN) |
3947e2f9 RH |
4135 | { |
4136 | HARD_REG_SET parm_regs; | |
4137 | int nparm_regs; | |
4138 | rtx p; | |
4139 | ||
4140 | /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers, | |
4141 | we search backward and place the instructions before the first | |
4142 | parameter is loaded. Do this for everyone for consistency and a | |
4143 | presumtion that we'll get better code elsewhere as well. */ | |
4144 | ||
4145 | /* It should always be the case that we can put these instructions | |
a65f3558 JL |
4146 | anywhere in the basic block with performing PRE optimizations. |
4147 | Check this. */ | |
4148 | if (pre | |
4149 | && !TEST_BIT (antloc[bb], expr->bitmap_index) | |
4150 | && !TEST_BIT (transp[bb], expr->bitmap_index)) | |
3947e2f9 RH |
4151 | abort (); |
4152 | ||
4153 | /* Since different machines initialize their parameter registers | |
4154 | in different orders, assume nothing. Collect the set of all | |
4155 | parameter registers. */ | |
4156 | CLEAR_HARD_REG_SET (parm_regs); | |
4157 | nparm_regs = 0; | |
4158 | for (p = CALL_INSN_FUNCTION_USAGE (insn); p ; p = XEXP (p, 1)) | |
4159 | if (GET_CODE (XEXP (p, 0)) == USE | |
4160 | && GET_CODE (XEXP (XEXP (p, 0), 0)) == REG) | |
4161 | { | |
4162 | int regno = REGNO (XEXP (XEXP (p, 0), 0)); | |
4163 | if (regno >= FIRST_PSEUDO_REGISTER) | |
5c35539b | 4164 | abort (); |
3947e2f9 RH |
4165 | SET_HARD_REG_BIT (parm_regs, regno); |
4166 | nparm_regs++; | |
4167 | } | |
4168 | ||
4169 | /* Search backward for the first set of a register in this set. */ | |
4170 | while (nparm_regs && BLOCK_HEAD (bb) != insn) | |
4171 | { | |
4172 | insn = PREV_INSN (insn); | |
4173 | p = single_set (insn); | |
4174 | if (p && GET_CODE (SET_DEST (p)) == REG | |
4175 | && REGNO (SET_DEST (p)) < FIRST_PSEUDO_REGISTER | |
4176 | && TEST_HARD_REG_BIT (parm_regs, REGNO (SET_DEST (p)))) | |
4177 | { | |
4178 | CLEAR_HARD_REG_BIT (parm_regs, REGNO (SET_DEST (p))); | |
4179 | nparm_regs--; | |
4180 | } | |
4181 | } | |
4182 | ||
4183 | new_insn = emit_insn_before (pat, insn); | |
4184 | if (BLOCK_HEAD (bb) == insn) | |
4185 | BLOCK_HEAD (bb) = new_insn; | |
7506f491 DE |
4186 | } |
4187 | else | |
4188 | { | |
4189 | new_insn = emit_insn_after (pat, insn); | |
4190 | BLOCK_END (bb) = new_insn; | |
7506f491 DE |
4191 | } |
4192 | ||
a65f3558 JL |
4193 | /* Keep block number table up to date. |
4194 | Note, PAT could be a multiple insn sequence, we have to make | |
4195 | sure that each insn in the sequence is handled. */ | |
4196 | if (GET_CODE (pat) == SEQUENCE) | |
4197 | { | |
4198 | int i; | |
4199 | ||
4200 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
4201 | { | |
4202 | rtx insn = XVECEXP (pat, 0, i); | |
4203 | set_block_num (insn, bb); | |
4204 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
4205 | add_label_notes (PATTERN (insn), new_insn); | |
4206 | record_set_insn = insn; | |
4207 | note_stores (PATTERN (insn), record_set_info); | |
4208 | } | |
4209 | } | |
4210 | else | |
4211 | { | |
4212 | add_label_notes (SET_SRC (pat), new_insn); | |
4213 | set_block_num (new_insn, bb); | |
4214 | /* Keep register set table up to date. */ | |
4215 | record_one_set (regno, new_insn); | |
4216 | } | |
3947e2f9 | 4217 | |
7506f491 DE |
4218 | gcse_create_count++; |
4219 | ||
4220 | if (gcse_file) | |
4221 | { | |
a65f3558 | 4222 | fprintf (gcse_file, "PRE/HOIST: end of bb %d, insn %d, copying expression %d to reg %d\n", |
7506f491 DE |
4223 | bb, INSN_UID (new_insn), expr->bitmap_index, regno); |
4224 | } | |
4225 | } | |
4226 | ||
4227 | /* Insert partially redundant expressions at the ends of appropriate basic | |
a65f3558 | 4228 | blocks making them fully redundant. */ |
7506f491 DE |
4229 | |
4230 | static void | |
4231 | pre_insert (index_map) | |
4232 | struct expr **index_map; | |
4233 | { | |
a65f3558 JL |
4234 | int bb, i, set_size; |
4235 | sbitmap *inserted; | |
4236 | ||
4237 | /* Compute INSERT = PRE_OPTIMAL & ~PRE_REDUNDANT. | |
4238 | Where INSERT is nonzero, we add the expression at the end of the basic | |
4239 | block if it reaches any of the deleted expressions. */ | |
7506f491 | 4240 | |
a65f3558 JL |
4241 | set_size = pre_optimal[0]->size; |
4242 | inserted = sbitmap_vector_alloc (n_basic_blocks, n_exprs); | |
4243 | sbitmap_vector_zero (inserted, n_basic_blocks); | |
7506f491 | 4244 | |
7506f491 DE |
4245 | for (bb = 0; bb < n_basic_blocks; bb++) |
4246 | { | |
4247 | int indx; | |
a65f3558 JL |
4248 | |
4249 | /* This computes the number of potential insertions we need. */ | |
4250 | sbitmap_not (temp_bitmap[bb], pre_redundant[bb]); | |
4251 | sbitmap_a_and_b (temp_bitmap[bb], temp_bitmap[bb], pre_optimal[bb]); | |
4252 | ||
4253 | /* TEMP_BITMAP[bb] now contains a bitmap of the expressions that we need | |
4254 | to insert at the end of this basic block. */ | |
4255 | for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS) | |
7506f491 | 4256 | { |
a65f3558 | 4257 | SBITMAP_ELT_TYPE insert = temp_bitmap[bb]->elms[i]; |
7506f491 | 4258 | int j; |
7506f491 | 4259 | |
a65f3558 | 4260 | for (j = indx; insert && j < n_exprs; j++, insert >>= 1) |
7506f491 | 4261 | { |
a65f3558 JL |
4262 | if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX) |
4263 | { | |
4264 | struct expr *expr = index_map[j]; | |
4265 | struct occr *occr; | |
4266 | ||
4267 | /* Now look at each deleted occurence of this expression. */ | |
4268 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
4269 | { | |
4270 | if (! occr->deleted_p) | |
4271 | continue; | |
4272 | ||
4273 | /* Insert this expression at the end of BB if it would | |
4274 | reach the deleted occurence. */ | |
4275 | if (!TEST_BIT (inserted[bb], j) | |
4276 | && pre_expr_reaches_here_p (bb, expr, | |
4277 | BLOCK_NUM (occr->insn), 0, | |
4278 | NULL)) | |
4279 | { | |
4280 | SET_BIT (inserted[bb], j); | |
4281 | insert_insn_end_bb (index_map[j], bb, 1); | |
4282 | } | |
4283 | } | |
4284 | } | |
7506f491 DE |
4285 | } |
4286 | } | |
4287 | } | |
4288 | } | |
4289 | ||
4290 | /* Copy the result of INSN to REG. | |
4291 | INDX is the expression number. */ | |
4292 | ||
4293 | static void | |
4294 | pre_insert_copy_insn (expr, insn) | |
4295 | struct expr *expr; | |
4296 | rtx insn; | |
4297 | { | |
4298 | rtx reg = expr->reaching_reg; | |
4299 | int regno = REGNO (reg); | |
4300 | int indx = expr->bitmap_index; | |
4301 | rtx set = single_set (insn); | |
4302 | rtx new_insn; | |
4303 | ||
4304 | if (!set) | |
4305 | abort (); | |
9e6a5703 | 4306 | new_insn = emit_insn_after (gen_rtx_SET (VOIDmode, reg, SET_DEST (set)), |
7506f491 DE |
4307 | insn); |
4308 | /* Keep block number table up to date. */ | |
4309 | set_block_num (new_insn, BLOCK_NUM (insn)); | |
4310 | /* Keep register set table up to date. */ | |
4311 | record_one_set (regno, new_insn); | |
4312 | ||
4313 | gcse_create_count++; | |
4314 | ||
4315 | if (gcse_file) | |
4316 | { | |
4317 | fprintf (gcse_file, "PRE: bb %d, insn %d, copying expression %d in insn %d to reg %d\n", | |
4318 | BLOCK_NUM (insn), INSN_UID (new_insn), indx, INSN_UID (insn), regno); | |
4319 | } | |
4320 | } | |
4321 | ||
4322 | /* Copy available expressions that reach the redundant expression | |
4323 | to `reaching_reg'. */ | |
4324 | ||
4325 | static void | |
4326 | pre_insert_copies () | |
4327 | { | |
a65f3558 JL |
4328 | int i, bb; |
4329 | ||
4330 | for (bb = 0; bb < n_basic_blocks; bb++) | |
4331 | { | |
4332 | sbitmap_a_and_b (temp_bitmap[bb], pre_optimal[bb], pre_redundant[bb]); | |
4333 | } | |
7506f491 DE |
4334 | |
4335 | /* For each available expression in the table, copy the result to | |
4336 | `reaching_reg' if the expression reaches a deleted one. | |
4337 | ||
4338 | ??? The current algorithm is rather brute force. | |
4339 | Need to do some profiling. */ | |
4340 | ||
4341 | for (i = 0; i < expr_hash_table_size; i++) | |
4342 | { | |
4343 | struct expr *expr; | |
4344 | ||
4345 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
4346 | { | |
4347 | struct occr *occr; | |
4348 | ||
4349 | /* If the basic block isn't reachable, PPOUT will be TRUE. | |
4350 | However, we don't want to insert a copy here because the | |
4351 | expression may not really be redundant. So only insert | |
4352 | an insn if the expression was deleted. | |
4353 | This test also avoids further processing if the expression | |
4354 | wasn't deleted anywhere. */ | |
4355 | if (expr->reaching_reg == NULL) | |
4356 | continue; | |
4357 | ||
4358 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
4359 | { | |
4360 | struct occr *avail; | |
4361 | ||
4362 | if (! occr->deleted_p) | |
4363 | continue; | |
4364 | ||
4365 | for (avail = expr->avail_occr; avail != NULL; avail = avail->next) | |
4366 | { | |
4367 | rtx insn = avail->insn; | |
a65f3558 JL |
4368 | int bb = BLOCK_NUM (insn); |
4369 | ||
4370 | if (!TEST_BIT (temp_bitmap[bb], expr->bitmap_index)) | |
4371 | continue; | |
7506f491 DE |
4372 | |
4373 | /* No need to handle this one if handled already. */ | |
4374 | if (avail->copied_p) | |
4375 | continue; | |
4376 | /* Don't handle this one if it's a redundant one. */ | |
a65f3558 | 4377 | if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn))) |
7506f491 DE |
4378 | continue; |
4379 | /* Or if the expression doesn't reach the deleted one. */ | |
a65f3558 | 4380 | if (! pre_expr_reaches_here_p (BLOCK_NUM (avail->insn), expr, |
7506f491 | 4381 | BLOCK_NUM (occr->insn), |
a65f3558 | 4382 | 1, NULL)) |
7506f491 DE |
4383 | continue; |
4384 | ||
4385 | /* Copy the result of avail to reaching_reg. */ | |
4386 | pre_insert_copy_insn (expr, insn); | |
4387 | avail->copied_p = 1; | |
4388 | } | |
4389 | } | |
4390 | } | |
4391 | } | |
4392 | } | |
4393 | ||
4394 | /* Delete redundant computations. | |
7506f491 DE |
4395 | Deletion is done by changing the insn to copy the `reaching_reg' of |
4396 | the expression into the result of the SET. It is left to later passes | |
4397 | (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it. | |
4398 | ||
4399 | Returns non-zero if a change is made. */ | |
4400 | ||
4401 | static int | |
4402 | pre_delete () | |
4403 | { | |
a65f3558 JL |
4404 | int i, bb, changed; |
4405 | ||
4406 | /* Compute the expressions which are redundant and need to be replaced by | |
4407 | copies from the reaching reg to the target reg. */ | |
4408 | for (bb = 0; bb < n_basic_blocks; bb++) | |
4409 | { | |
4410 | sbitmap_not (temp_bitmap[bb], pre_optimal[bb]); | |
4411 | sbitmap_a_and_b (temp_bitmap[bb], temp_bitmap[bb], pre_redundant[bb]); | |
4412 | } | |
7506f491 DE |
4413 | |
4414 | changed = 0; | |
4415 | for (i = 0; i < expr_hash_table_size; i++) | |
4416 | { | |
4417 | struct expr *expr; | |
4418 | ||
4419 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
4420 | { | |
4421 | struct occr *occr; | |
4422 | int indx = expr->bitmap_index; | |
4423 | ||
4424 | /* We only need to search antic_occr since we require | |
4425 | ANTLOC != 0. */ | |
4426 | ||
4427 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
4428 | { | |
4429 | rtx insn = occr->insn; | |
4430 | rtx set; | |
4431 | int bb = BLOCK_NUM (insn); | |
7506f491 | 4432 | |
a65f3558 | 4433 | if (TEST_BIT (temp_bitmap[bb], indx)) |
7506f491 | 4434 | { |
7506f491 DE |
4435 | set = single_set (insn); |
4436 | if (! set) | |
4437 | abort (); | |
4438 | ||
d3903c22 JL |
4439 | /* Create a pseudo-reg to store the result of reaching |
4440 | expressions into. Get the mode for the new pseudo | |
4441 | from the mode of the original destination pseudo. */ | |
4442 | if (expr->reaching_reg == NULL) | |
4443 | expr->reaching_reg | |
4444 | = gen_reg_rtx (GET_MODE (SET_DEST (set))); | |
4445 | ||
7506f491 DE |
4446 | /* In theory this should never fail since we're creating |
4447 | a reg->reg copy. | |
4448 | ||
4449 | However, on the x86 some of the movXX patterns actually | |
4450 | contain clobbers of scratch regs. This may cause the | |
db35306d | 4451 | insn created by validate_change to not match any pattern |
7506f491 DE |
4452 | and thus cause validate_change to fail. */ |
4453 | if (validate_change (insn, &SET_SRC (set), | |
4454 | expr->reaching_reg, 0)) | |
4455 | { | |
4456 | occr->deleted_p = 1; | |
a65f3558 | 4457 | SET_BIT (pre_redundant_insns, INSN_CUID (insn)); |
7506f491 DE |
4458 | changed = 1; |
4459 | gcse_subst_count++; | |
4460 | } | |
4461 | ||
4462 | if (gcse_file) | |
4463 | { | |
a65f3558 JL |
4464 | fprintf (gcse_file, |
4465 | "PRE: redundant insn %d (expression %d) in bb %d, reaching reg is %d\n", | |
7506f491 DE |
4466 | INSN_UID (insn), indx, bb, REGNO (expr->reaching_reg)); |
4467 | } | |
4468 | } | |
4469 | } | |
4470 | } | |
4471 | } | |
4472 | ||
4473 | return changed; | |
4474 | } | |
4475 | ||
4476 | /* Perform GCSE optimizations using PRE. | |
4477 | This is called by one_pre_gcse_pass after all the dataflow analysis | |
4478 | has been done. | |
4479 | ||
a65f3558 JL |
4480 | This is based on the original Morel-Renvoise paper Fred Chow's thesis, |
4481 | and lazy code motion from Knoop, Ruthing and Steffen as described in | |
4482 | Advanced Compiler Design and Implementation. | |
7506f491 DE |
4483 | |
4484 | ??? A new pseudo reg is created to hold the reaching expression. | |
4485 | The nice thing about the classical approach is that it would try to | |
4486 | use an existing reg. If the register can't be adequately optimized | |
4487 | [i.e. we introduce reload problems], one could add a pass here to | |
4488 | propagate the new register through the block. | |
4489 | ||
4490 | ??? We don't handle single sets in PARALLELs because we're [currently] | |
4491 | not able to copy the rest of the parallel when we insert copies to create | |
4492 | full redundancies from partial redundancies. However, there's no reason | |
4493 | why we can't handle PARALLELs in the cases where there are no partial | |
4494 | redundancies. */ | |
4495 | ||
4496 | static int | |
4497 | pre_gcse () | |
4498 | { | |
4499 | int i; | |
4500 | int changed; | |
4501 | struct expr **index_map; | |
4502 | ||
4503 | /* Compute a mapping from expression number (`bitmap_index') to | |
4504 | hash table entry. */ | |
4505 | ||
4506 | index_map = (struct expr **) alloca (n_exprs * sizeof (struct expr *)); | |
4507 | bzero ((char *) index_map, n_exprs * sizeof (struct expr *)); | |
4508 | for (i = 0; i < expr_hash_table_size; i++) | |
4509 | { | |
4510 | struct expr *expr; | |
4511 | ||
4512 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
4513 | index_map[expr->bitmap_index] = expr; | |
4514 | } | |
4515 | ||
4516 | /* Reset bitmap used to track which insns are redundant. */ | |
a65f3558 JL |
4517 | pre_redundant_insns = sbitmap_alloc (max_cuid); |
4518 | sbitmap_zero (pre_redundant_insns); | |
7506f491 DE |
4519 | |
4520 | /* Delete the redundant insns first so that | |
4521 | - we know what register to use for the new insns and for the other | |
4522 | ones with reaching expressions | |
4523 | - we know which insns are redundant when we go to create copies */ | |
4524 | changed = pre_delete (); | |
4525 | ||
4526 | /* Insert insns in places that make partially redundant expressions | |
4527 | fully redundant. */ | |
4528 | pre_insert (index_map); | |
4529 | ||
4530 | /* In other places with reaching expressions, copy the expression to the | |
4531 | specially allocated pseudo-reg that reaches the redundant expression. */ | |
4532 | pre_insert_copies (); | |
4533 | ||
a65f3558 | 4534 | free (pre_redundant_insns); |
7506f491 DE |
4535 | |
4536 | return changed; | |
4537 | } | |
4538 | ||
4539 | /* Top level routine to perform one PRE GCSE pass. | |
4540 | ||
4541 | Return non-zero if a change was made. */ | |
4542 | ||
4543 | static int | |
b5ce41ff | 4544 | one_pre_gcse_pass (pass) |
7506f491 DE |
4545 | int pass; |
4546 | { | |
4547 | int changed = 0; | |
4548 | ||
4549 | gcse_subst_count = 0; | |
4550 | gcse_create_count = 0; | |
4551 | ||
4552 | alloc_expr_hash_table (max_cuid); | |
b5ce41ff | 4553 | compute_expr_hash_table (); |
7506f491 DE |
4554 | if (gcse_file) |
4555 | dump_hash_table (gcse_file, "Expression", expr_hash_table, | |
4556 | expr_hash_table_size, n_exprs); | |
4557 | if (n_exprs > 0) | |
4558 | { | |
4559 | alloc_pre_mem (n_basic_blocks, n_exprs); | |
4560 | compute_pre_data (); | |
4561 | changed |= pre_gcse (); | |
4562 | free_pre_mem (); | |
4563 | } | |
4564 | free_expr_hash_table (); | |
4565 | ||
4566 | if (gcse_file) | |
4567 | { | |
4568 | fprintf (gcse_file, "\n"); | |
4569 | fprintf (gcse_file, "PRE GCSE of %s, pass %d: %d bytes needed, %d substs, %d insns created\n", | |
4570 | current_function_name, pass, | |
4571 | bytes_used, gcse_subst_count, gcse_create_count); | |
4572 | } | |
4573 | ||
4574 | return changed; | |
4575 | } | |
aeb2f500 JW |
4576 | \f |
4577 | /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN. | |
4578 | We have to add REG_LABEL notes, because the following loop optimization | |
4579 | pass requires them. */ | |
4580 | ||
4581 | /* ??? This is very similar to the loop.c add_label_notes function. We | |
4582 | could probably share code here. */ | |
4583 | ||
4584 | /* ??? If there was a jump optimization pass after gcse and before loop, | |
4585 | then we would not need to do this here, because jump would add the | |
4586 | necessary REG_LABEL notes. */ | |
4587 | ||
4588 | static void | |
4589 | add_label_notes (x, insn) | |
4590 | rtx x; | |
4591 | rtx insn; | |
4592 | { | |
4593 | enum rtx_code code = GET_CODE (x); | |
4594 | int i, j; | |
4595 | char *fmt; | |
4596 | ||
4597 | if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x)) | |
4598 | { | |
6b3603c2 | 4599 | /* This code used to ignore labels that referred to dispatch tables to |
ac7c5af5 | 4600 | avoid flow generating (slighly) worse code. |
6b3603c2 | 4601 | |
ac7c5af5 JL |
4602 | We no longer ignore such label references (see LABEL_REF handling in |
4603 | mark_jump_label for additional information). */ | |
6b3603c2 JL |
4604 | REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, XEXP (x, 0), |
4605 | REG_NOTES (insn)); | |
aeb2f500 JW |
4606 | return; |
4607 | } | |
4608 | ||
4609 | fmt = GET_RTX_FORMAT (code); | |
4610 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
4611 | { | |
4612 | if (fmt[i] == 'e') | |
4613 | add_label_notes (XEXP (x, i), insn); | |
4614 | else if (fmt[i] == 'E') | |
4615 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
4616 | add_label_notes (XVECEXP (x, i, j), insn); | |
4617 | } | |
4618 | } | |
a65f3558 JL |
4619 | |
4620 | /* Compute transparent outgoing information for each block. | |
4621 | ||
4622 | An expression is transparent to an edge unless it is killed by | |
4623 | the edge itself. This can only happen with abnormal control flow, | |
4624 | when the edge is traversed through a call. This happens with | |
4625 | non-local labels and exceptions. | |
4626 | ||
4627 | This would not be necessary if we split the edge. While this is | |
4628 | normally impossible for abnormal critical edges, with some effort | |
4629 | it should be possible with exception handling, since we still have | |
4630 | control over which handler should be invoked. But due to increased | |
4631 | EH table sizes, this may not be worthwhile. */ | |
4632 | ||
4633 | static void | |
4634 | compute_transpout () | |
4635 | { | |
4636 | int bb; | |
4637 | ||
4638 | sbitmap_vector_ones (transpout, n_basic_blocks); | |
4639 | ||
4640 | for (bb = 0; bb < n_basic_blocks; ++bb) | |
4641 | { | |
4642 | int i; | |
4643 | ||
4644 | /* Note that flow inserted a nop a the end of basic blocks that | |
4645 | end in call instructions for reasons other than abnormal | |
4646 | control flow. */ | |
4647 | if (GET_CODE (BLOCK_END (bb)) != CALL_INSN) | |
4648 | continue; | |
4649 | ||
4650 | for (i = 0; i < expr_hash_table_size; i++) | |
4651 | { | |
4652 | struct expr *expr; | |
4653 | for (expr = expr_hash_table[i]; expr ; expr = expr->next_same_hash) | |
4654 | if (GET_CODE (expr->expr) == MEM) | |
4655 | { | |
4656 | rtx addr = XEXP (expr->expr, 0); | |
4657 | ||
4658 | if (GET_CODE (addr) == SYMBOL_REF | |
4659 | && CONSTANT_POOL_ADDRESS_P (addr)) | |
4660 | continue; | |
4661 | ||
4662 | /* ??? Optimally, we would use interprocedural alias | |
4663 | analysis to determine if this mem is actually killed | |
4664 | by this call. */ | |
4665 | RESET_BIT (transpout[bb], expr->bitmap_index); | |
4666 | } | |
4667 | } | |
4668 | } | |
4669 | } |