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7506f491 DE |
1 | /* Global common subexpression elimination |
2 | and global constant/copy propagation for GNU compiler. | |
a5acf2a1 | 3 | Copyright (C) 1997, 1998 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. | |
27 | - memory aliasing support | |
28 | - ability to realloc sbitmap vectors would allow one initial computation | |
29 | of reg_set_in_block with only subsequent additions, rather than | |
30 | recomputing it for each pass | |
31 | ||
32 | NOTES | |
33 | - the classic gcse implementation is kept in for now for comparison | |
34 | */ | |
35 | ||
36 | /* References searched while implementing this. | |
37 | This list will eventually be deleted but I wanted to have a record of it | |
38 | for now. | |
39 | ||
40 | Compilers Principles, Techniques and Tools | |
41 | Aho, Sethi, Ullman | |
42 | Addison-Wesley, 1988 | |
43 | ||
44 | Global Optimization by Suppression of Partial Redundancies | |
45 | E. Morel, C. Renvoise | |
46 | communications of the acm, Vol. 22, Num. 2, Feb. 1979 | |
47 | ||
48 | A Portable Machine-Independent Global Optimizer - Design and Measurements | |
49 | Frederick Chow | |
50 | Stanford Ph.D. thesis, Dec. 1983 | |
51 | ||
52 | xxx | |
53 | Elimination Algorithms for Data Flow Analysis | |
54 | B.G. Ryder, M.C. Paull | |
55 | ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986 | |
56 | ||
57 | reread | |
58 | A Fast Algorithm for Code Movement Optimization | |
59 | D.M. Dhamdhere | |
60 | SIGPLAN Notices, Vol. 23, Num. 10, Oct. 1988 | |
61 | ||
62 | A Solution to a Problem with Morel and Renvoise's | |
63 | Global Optimization by Suppression of Partial Redundancies | |
64 | K-H Drechsler, M.P. Stadel | |
65 | ACM TOPLAS, Vol. 10, Num. 4, Oct. 1988 | |
66 | ||
67 | Practical Adaptation of the Global Optimization | |
68 | Algorithm of Morel and Renvoise | |
69 | D.M. Dhamdhere | |
70 | ACM TOPLAS, Vol. 13, Num. 2. Apr. 1991 | |
71 | ||
72 | Efficiently Computing Static Single Assignment Form and the Control | |
73 | Dependence Graph | |
74 | R. Cytron, J. Ferrante, B.K. Rosen, M.N. Wegman, and F.K. Zadeck | |
75 | ACM TOPLAS, Vol. 13, Num. 4, Oct. 1991 | |
76 | ||
77 | yyy | |
78 | How to Analyze Large Programs Efficiently and Informatively | |
79 | D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck | |
80 | ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI | |
81 | ||
82 | Lazy Code Motion | |
83 | J. Knoop, O. Ruthing, B. Steffen | |
84 | ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI | |
85 | ||
86 | What's In a Region? Or Computing Control Dependence Regions in Near-Linear | |
87 | Time for Reducible Flow Control | |
88 | Thomas Ball | |
89 | ACM Letters on Programming Languages and Systems, | |
90 | Vol. 2, Num. 1-4, Mar-Dec 1993 | |
91 | ||
92 | An Efficient Representation for Sparse Sets | |
93 | Preston Briggs, Linda Torczon | |
94 | ACM Letters on Programming Languages and Systems, | |
95 | Vol. 2, Num. 1-4, Mar-Dec 1993 | |
96 | ||
97 | A Variation of Knoop, Ruthing, and Steffen's Lazy Code Motion | |
98 | K-H Drechsler, M.P. Stadel | |
99 | ACM SIGPLAN Notices, Vol. 28, Num. 5, May 1993 | |
100 | ||
101 | Partial Dead Code Elimination | |
102 | J. Knoop, O. Ruthing, B. Steffen | |
103 | ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994 | |
104 | ||
105 | Effective Partial Redundancy Elimination | |
106 | P. Briggs, K.D. Cooper | |
107 | ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994 | |
108 | ||
109 | The Program Structure Tree: Computing Control Regions in Linear Time | |
110 | R. Johnson, D. Pearson, K. Pingali | |
111 | ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994 | |
112 | ||
113 | Optimal Code Motion: Theory and Practice | |
114 | J. Knoop, O. Ruthing, B. Steffen | |
115 | ACM TOPLAS, Vol. 16, Num. 4, Jul. 1994 | |
116 | ||
117 | The power of assignment motion | |
118 | J. Knoop, O. Ruthing, B. Steffen | |
119 | ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI | |
120 | ||
121 | Global code motion / global value numbering | |
122 | C. Click | |
123 | ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI | |
124 | ||
125 | Value Driven Redundancy Elimination | |
126 | L.T. Simpson | |
127 | Rice University Ph.D. thesis, Apr. 1996 | |
128 | ||
129 | Value Numbering | |
130 | L.T. Simpson | |
131 | Massively Scalar Compiler Project, Rice University, Sep. 1996 | |
132 | ||
133 | High Performance Compilers for Parallel Computing | |
134 | Michael Wolfe | |
135 | Addison-Wesley, 1996 | |
136 | ||
137 | People wishing to speed up the code here should read xxx, yyy. | |
138 | People wishing to do something different can find various possibilities | |
139 | in the above papers and elsewhere. | |
140 | */ | |
141 | ||
142 | #include "config.h" | |
143 | /* Must precede rtl.h for FFS. */ | |
50b2596f | 144 | #include "system.h" |
7506f491 DE |
145 | |
146 | #include "rtl.h" | |
147 | #include "regs.h" | |
148 | #include "hard-reg-set.h" | |
149 | #include "flags.h" | |
150 | #include "real.h" | |
151 | #include "insn-config.h" | |
152 | #include "recog.h" | |
153 | #include "basic-block.h" | |
50b2596f | 154 | #include "output.h" |
3cdbd1f8 | 155 | #include "expr.h" |
7506f491 DE |
156 | |
157 | #include "obstack.h" | |
158 | #define obstack_chunk_alloc gmalloc | |
159 | #define obstack_chunk_free free | |
160 | ||
161 | /* Maximum number of passes to perform. */ | |
162 | #define MAX_PASSES 1 | |
163 | ||
164 | /* Propagate flow information through back edges and thus enable PRE's | |
165 | moving loop invariant calculations out of loops. | |
166 | ||
167 | Originally this tended to create worse overall code, but several | |
168 | improvements during the development of PRE seem to have made following | |
169 | back edges generally a win. | |
170 | ||
171 | Note much of the loop invariant code motion done here would normally | |
172 | be done by loop.c, which has more heuristics for when to move invariants | |
173 | out of loops. At some point we might need to move some of those | |
174 | heuristics into gcse.c. */ | |
175 | #define FOLLOW_BACK_EDGES 1 | |
176 | ||
177 | /* We support two GCSE implementations: Classic GCSE (i.e. Dragon Book) | |
178 | and PRE (Partial Redundancy Elimination) GCSE (based on Fred Chow's thesis). | |
179 | The default is PRE. | |
180 | ||
181 | In either case we perform the following steps: | |
182 | ||
183 | 1) Compute basic block information. | |
184 | ||
185 | 2) Compute table of places where registers are set. | |
186 | ||
187 | 3) Perform copy/constant propagation. | |
188 | ||
189 | 4) Perform global cse. | |
190 | ||
191 | 5) Perform another pass of copy/constant propagation [only if PRE]. | |
192 | ||
193 | Two passes of copy/constant propagation are done because the first one | |
194 | enables more GCSE and the second one helps to clean up the copies that | |
195 | GCSE creates. This is needed more for PRE than for Classic because Classic | |
196 | GCSE will try to use an existing register containing the common | |
197 | subexpression rather than create a new one. This is harder to do for PRE | |
198 | because of the code motion (which Classic GCSE doesn't do). | |
199 | ||
200 | Expressions we are interested in GCSE-ing are of the form | |
201 | (set (pseudo-reg) (expression)). | |
202 | Function want_to_gcse_p says what these are. | |
203 | ||
204 | PRE handles moving invariant expressions out of loops (by treating them as | |
205 | partially redundant). This feature of PRE is disabled here (by not | |
206 | propagating dataflow information along back edges) because loop.c has more | |
207 | involved (and thus typically better) heuristics for what to move out of | |
208 | loops. | |
209 | ||
210 | Eventually it would be nice to replace cse.c/gcse.c with SSA (static single | |
211 | assignment) based GVN (global value numbering). L. T. Simpson's paper | |
212 | (Rice University) on value numbering is a useful reference for this. | |
213 | ||
214 | ********************** | |
215 | ||
216 | We used to support multiple passes but there are diminishing returns in | |
217 | doing so. The first pass usually makes 90% of the changes that are doable. | |
218 | A second pass can make a few more changes made possible by the first pass. | |
219 | Experiments show any further passes don't make enough changes to justify | |
220 | the expense. | |
221 | ||
222 | A study of spec92 using an unlimited number of passes: | |
223 | [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83, | |
224 | [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2, | |
225 | [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1 | |
226 | ||
227 | It was found doing copy propagation between each pass enables further | |
228 | substitutions. | |
229 | ||
230 | PRE is quite expensive in complicated functions because the DFA can take | |
231 | awhile to converge. Hence we only perform one pass. Macro MAX_PASSES can | |
232 | be modified if one wants to experiment. | |
233 | ||
234 | ********************** | |
235 | ||
236 | The steps for PRE are: | |
237 | ||
238 | 1) Build the hash table of expressions we wish to GCSE (expr_hash_table). | |
239 | ||
240 | 2) Perform the data flow analysis for PRE. | |
241 | ||
242 | 3) Delete the redundant instructions | |
243 | ||
244 | 4) Insert the required copies [if any] that make the partially | |
245 | redundant instructions fully redundant. | |
246 | ||
247 | 5) For other reaching expressions, insert an instruction to copy the value | |
248 | to a newly created pseudo that will reach the redundant instruction. | |
249 | ||
250 | The deletion is done first so that when we do insertions we | |
251 | know which pseudo reg to use. | |
252 | ||
253 | Various papers have argued that PRE DFA is expensive (O(n^2)) and others | |
254 | argue it is not. The number of iterations for the algorithm to converge | |
255 | is typically 2-4 so I don't view it as that expensive (relatively speaking). | |
256 | ||
257 | PRE GCSE depends heavily on the seconds CSE pass to clean up the copies | |
258 | we create. To make an expression reach the place where it's redundant, | |
259 | the result of the expression is copied to a new register, and the redundant | |
260 | expression is deleted by replacing it with this new register. Classic GCSE | |
261 | doesn't have this problem as much as it computes the reaching defs of | |
262 | each register in each block and thus can try to use an existing register. | |
263 | ||
264 | ********************** | |
265 | ||
266 | When -fclassic-gcse, we perform a classic global CSE pass. | |
267 | It is based on the algorithms in the Dragon book, and is based on code | |
268 | written by Devor Tevi at Intel. | |
269 | ||
270 | The steps for Classic GCSE are: | |
271 | ||
272 | 1) Build the hash table of expressions we wish to GCSE (expr_hash_table). | |
273 | Also recorded are reaching definition "gen" statements (rd_gen) | |
274 | ||
275 | 2) Compute the reaching definitions (reaching_defs). | |
276 | This is a bitmap for each basic block indexed by INSN_CUID that is 1 | |
277 | for each statement containing a definition that reaches the block. | |
278 | ||
279 | 3) Compute the available expressions (ae_in). | |
280 | This is a bitmap for each basic block indexed by expression number | |
281 | that is 1 for each expression that is available at the beginning of | |
282 | the block. | |
283 | ||
284 | 4) Perform GCSE. | |
285 | This is done by scanning each instruction looking for sets of the form | |
286 | (set (pseudo-reg) (expression)) and checking if `expression' is in the | |
287 | hash table. If it is, and if the expression is available, and if only | |
288 | one computation of the expression reaches the instruction, we substitute | |
289 | the expression for a register containing its value. If there is no | |
290 | such register, but the expression is expensive enough we create an | |
291 | instruction to copy the result of the expression into and use that. | |
292 | ||
293 | ********************** | |
294 | ||
295 | A fair bit of simplicity is created by creating small functions for simple | |
296 | tasks, even when the function is only called in one place. This may | |
297 | measurably slow things down [or may not] by creating more function call | |
298 | overhead than is necessary. The source is laid out so that it's trivial | |
299 | to make the affected functions inline so that one can measure what speed | |
300 | up, if any, can be achieved, and maybe later when things settle things can | |
301 | be rearranged. | |
302 | ||
303 | Help stamp out big monolithic functions! */ | |
304 | \f | |
305 | /* GCSE global vars. */ | |
306 | ||
307 | /* -dG dump file. */ | |
308 | static FILE *gcse_file; | |
309 | ||
310 | /* Bitmaps are normally not included in debugging dumps. | |
311 | However it's useful to be able to print them from GDB. | |
312 | We could create special functions for this, but it's simpler to | |
313 | just allow passing stderr to the dump_foo fns. Since stderr can | |
314 | be a macro, we store a copy here. */ | |
315 | static FILE *debug_stderr; | |
316 | ||
317 | /* An obstack for our working variables. */ | |
318 | static struct obstack gcse_obstack; | |
319 | ||
320 | /* Non-zero for each mode that supports (set (reg) (reg)). | |
321 | This is trivially true for integer and floating point values. | |
322 | It may or may not be true for condition codes. */ | |
323 | static char can_copy_p[(int) NUM_MACHINE_MODES]; | |
324 | ||
325 | /* Non-zero if can_copy_p has been initialized. */ | |
326 | static int can_copy_init_p; | |
327 | ||
328 | /* Element I is a list of I's predecessors/successors. */ | |
329 | static int_list_ptr *s_preds; | |
330 | static int_list_ptr *s_succs; | |
331 | ||
332 | /* Element I is the number of predecessors/successors of basic block I. */ | |
333 | static int *num_preds; | |
334 | static int *num_succs; | |
335 | ||
336 | /* Hash table of expressions. */ | |
337 | ||
338 | struct expr | |
339 | { | |
340 | /* The expression (SET_SRC for expressions, PATTERN for assignments). */ | |
341 | rtx expr; | |
342 | /* Index in the available expression bitmaps. */ | |
343 | int bitmap_index; | |
344 | /* Next entry with the same hash. */ | |
345 | struct expr *next_same_hash; | |
346 | /* List of anticipatable occurrences in basic blocks in the function. | |
347 | An "anticipatable occurrence" is one that is the first occurrence in the | |
348 | basic block and the operands are not modified in the basic block prior | |
349 | to the occurrence. */ | |
350 | struct occr *antic_occr; | |
351 | /* List of available occurrence in basic blocks in the function. | |
352 | An "available occurrence" is one that is the last occurrence in the | |
353 | basic block and the operands are not modified by following statements in | |
354 | the basic block [including this insn]. */ | |
355 | struct occr *avail_occr; | |
356 | /* Non-null if the computation is PRE redundant. | |
357 | The value is the newly created pseudo-reg to record a copy of the | |
358 | expression in all the places that reach the redundant copy. */ | |
359 | rtx reaching_reg; | |
360 | }; | |
361 | ||
362 | /* Occurrence of an expression. | |
363 | There is one per basic block. If a pattern appears more than once the | |
364 | last appearance is used [or first for anticipatable expressions]. */ | |
365 | ||
366 | struct occr | |
367 | { | |
368 | /* Next occurrence of this expression. */ | |
369 | struct occr *next; | |
370 | /* The insn that computes the expression. */ | |
371 | rtx insn; | |
372 | /* Non-zero if this [anticipatable] occurrence has been deleted. */ | |
373 | char deleted_p; | |
374 | /* Non-zero if this [available] occurrence has been copied to | |
375 | reaching_reg. */ | |
376 | /* ??? This is mutually exclusive with deleted_p, so they could share | |
377 | the same byte. */ | |
378 | char copied_p; | |
379 | }; | |
380 | ||
381 | /* Expression and copy propagation hash tables. | |
382 | Each hash table is an array of buckets. | |
383 | ??? It is known that if it were an array of entries, structure elements | |
384 | `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is | |
385 | not clear whether in the final analysis a sufficient amount of memory would | |
386 | be saved as the size of the available expression bitmaps would be larger | |
387 | [one could build a mapping table without holes afterwards though]. | |
388 | Someday I'll perform the computation and figure it out. | |
389 | */ | |
390 | ||
391 | /* Total size of the expression hash table, in elements. */ | |
392 | static int expr_hash_table_size; | |
393 | /* The table itself. | |
394 | This is an array of `expr_hash_table_size' elements. */ | |
395 | static struct expr **expr_hash_table; | |
396 | ||
397 | /* Total size of the copy propagation hash table, in elements. */ | |
398 | static int set_hash_table_size; | |
399 | /* The table itself. | |
400 | This is an array of `set_hash_table_size' elements. */ | |
401 | static struct expr **set_hash_table; | |
402 | ||
403 | /* Mapping of uids to cuids. | |
404 | Only real insns get cuids. */ | |
405 | static int *uid_cuid; | |
406 | ||
407 | /* Highest UID in UID_CUID. */ | |
408 | static int max_uid; | |
409 | ||
410 | /* Get the cuid of an insn. */ | |
411 | #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)]) | |
412 | ||
413 | /* Number of cuids. */ | |
414 | static int max_cuid; | |
415 | ||
416 | /* Mapping of cuids to insns. */ | |
417 | static rtx *cuid_insn; | |
418 | ||
419 | /* Get insn from cuid. */ | |
420 | #define CUID_INSN(CUID) (cuid_insn[CUID]) | |
421 | ||
422 | /* Maximum register number in function prior to doing gcse + 1. | |
423 | Registers created during this pass have regno >= max_gcse_regno. | |
424 | This is named with "gcse" to not collide with global of same name. */ | |
425 | static int max_gcse_regno; | |
426 | ||
427 | /* Maximum number of cse-able expressions found. */ | |
428 | static int n_exprs; | |
429 | /* Maximum number of assignments for copy propagation found. */ | |
430 | static int n_sets; | |
431 | ||
432 | /* Table of registers that are modified. | |
433 | For each register, each element is a list of places where the pseudo-reg | |
434 | is set. | |
435 | ||
436 | For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only | |
437 | requires knowledge of which blocks kill which regs [and thus could use | |
438 | a bitmap instead of the lists `reg_set_table' uses]. The classic GCSE | |
439 | uses the information in lists. | |
440 | ||
441 | If the classic GCSE pass is deleted `reg_set_table' and could be turned | |
442 | into an array of bitmaps (num-bbs x num-regs) | |
443 | [however perhaps it may be useful to keep the data as is]. | |
444 | One advantage of recording things this way is that `reg_set_table' is | |
445 | fairly sparse with respect to pseudo regs but for hard regs could be | |
446 | fairly dense [relatively speaking]. | |
447 | And recording sets of pseudo-regs in lists speeds | |
448 | up functions like compute_transp since in the case of pseudo-regs we only | |
449 | need to iterate over the number of times a pseudo-reg is set, not over the | |
450 | number of basic blocks [clearly there is a bit of a slow down in the cases | |
451 | where a pseudo is set more than once in a block, however it is believed | |
452 | that the net effect is to speed things up]. This isn't done for hard-regs | |
453 | because recording call-clobbered hard-regs in `reg_set_table' at each | |
454 | function call can consume a fair bit of memory, and iterating over hard-regs | |
455 | stored this way in compute_transp will be more expensive. */ | |
456 | ||
457 | typedef struct reg_set { | |
458 | /* The next setting of this register. */ | |
459 | struct reg_set *next; | |
460 | /* The insn where it was set. */ | |
461 | rtx insn; | |
462 | } reg_set; | |
463 | static reg_set **reg_set_table; | |
464 | /* Size of `reg_set_table'. | |
465 | The table starts out at max_gcse_regno + slop, and is enlarged as | |
466 | necessary. */ | |
467 | static int reg_set_table_size; | |
468 | /* Amount to grow `reg_set_table' by when it's full. */ | |
469 | #define REG_SET_TABLE_SLOP 100 | |
470 | ||
471 | /* Bitmap containing one bit for each register in the program. | |
472 | Used when performing GCSE to track which registers have been set since | |
473 | the start of the basic block. */ | |
474 | static sbitmap reg_set_bitmap; | |
475 | ||
476 | /* For each block, a bitmap of registers set in the block. | |
477 | This is used by expr_killed_p and compute_transp. | |
478 | It is computed during hash table computation and not by compute_sets | |
479 | as it includes registers added since the last pass (or between cprop and | |
480 | gcse) and it's currently not easy to realloc sbitmap vectors. */ | |
481 | static sbitmap *reg_set_in_block; | |
482 | ||
483 | /* For each block, non-zero if memory is set in that block. | |
484 | This is computed during hash table computation and is used by | |
485 | expr_killed_p and compute_transp. | |
486 | ??? Handling of memory is very simple, we don't make any attempt | |
487 | to optimize things (later). | |
488 | ??? This can be computed by compute_sets since the information | |
489 | doesn't change. */ | |
490 | static char *mem_set_in_block; | |
491 | ||
492 | /* Various variables for statistics gathering. */ | |
493 | ||
494 | /* Memory used in a pass. | |
495 | This isn't intended to be absolutely precise. Its intent is only | |
496 | to keep an eye on memory usage. */ | |
497 | static int bytes_used; | |
498 | /* GCSE substitutions made. */ | |
499 | static int gcse_subst_count; | |
500 | /* Number of copy instructions created. */ | |
501 | static int gcse_create_count; | |
502 | /* Number of constants propagated. */ | |
503 | static int const_prop_count; | |
504 | /* Number of copys propagated. */ | |
505 | static int copy_prop_count; | |
506 | ||
507 | extern char *current_function_name; | |
508 | extern int current_function_calls_setjmp; | |
0e4347ce | 509 | extern int current_function_calls_longjmp; |
7506f491 DE |
510 | \f |
511 | /* These variables are used by classic GCSE. | |
512 | Normally they'd be defined a bit later, but `rd_gen' needs to | |
513 | be declared sooner. */ | |
514 | ||
515 | /* A bitmap of all ones for implementing the algorithm for available | |
516 | expressions and reaching definitions. */ | |
517 | /* ??? Available expression bitmaps have a different size than reaching | |
518 | definition bitmaps. This should be the larger of the two, however, it | |
519 | is not currently used for reaching definitions. */ | |
520 | static sbitmap u_bitmap; | |
521 | ||
522 | /* Each block has a bitmap of each type. | |
523 | The length of each blocks bitmap is: | |
524 | ||
525 | max_cuid - for reaching definitions | |
526 | n_exprs - for available expressions | |
527 | ||
528 | Thus we view the bitmaps as 2 dimensional arrays. i.e. | |
529 | rd_kill[block_num][cuid_num] | |
530 | ae_kill[block_num][expr_num] | |
531 | */ | |
532 | ||
533 | /* For reaching defs */ | |
534 | static sbitmap *rd_kill, *rd_gen, *reaching_defs, *rd_out; | |
535 | ||
536 | /* for available exprs */ | |
537 | static sbitmap *ae_kill, *ae_gen, *ae_in, *ae_out; | |
538 | \f | |
539 | static void compute_can_copy PROTO ((void)); | |
540 | ||
541 | static char *gmalloc PROTO ((unsigned int)); | |
542 | static char *grealloc PROTO ((char *, unsigned int)); | |
543 | static char *gcse_alloc PROTO ((unsigned long)); | |
544 | static void alloc_gcse_mem PROTO ((rtx)); | |
545 | static void free_gcse_mem PROTO ((void)); | |
50b2596f | 546 | extern void dump_cuid_table PROTO ((FILE *)); |
7506f491 DE |
547 | |
548 | static void alloc_reg_set_mem PROTO ((int)); | |
549 | static void free_reg_set_mem PROTO ((void)); | |
550 | static void record_one_set PROTO ((int, rtx)); | |
551 | static void record_set_info PROTO ((rtx, rtx)); | |
552 | static void compute_sets PROTO ((rtx)); | |
553 | ||
ed79bb3d | 554 | static void hash_scan_insn PROTO ((rtx, int, int)); |
7506f491 DE |
555 | static void hash_scan_set PROTO ((rtx, rtx, int)); |
556 | static void hash_scan_clobber PROTO ((rtx, rtx)); | |
557 | static void hash_scan_call PROTO ((rtx, rtx)); | |
558 | static void maybe_set_rd_gen PROTO ((int, rtx)); | |
559 | static int want_to_gcse_p PROTO ((rtx)); | |
560 | static int oprs_unchanged_p PROTO ((rtx, rtx, int)); | |
561 | static int oprs_anticipatable_p PROTO ((rtx, rtx)); | |
562 | static int oprs_available_p PROTO ((rtx, rtx)); | |
563 | static void insert_expr_in_table PROTO ((rtx, enum machine_mode, rtx, int, int)); | |
564 | static void insert_set_in_table PROTO ((rtx, rtx)); | |
565 | static unsigned int hash_expr PROTO ((rtx, enum machine_mode, int *, int)); | |
566 | static unsigned int hash_expr_1 PROTO ((rtx, enum machine_mode, int *)); | |
567 | static unsigned int hash_set PROTO ((int, int)); | |
568 | static int expr_equiv_p PROTO ((rtx, rtx)); | |
569 | static void record_last_reg_set_info PROTO ((rtx, int)); | |
570 | static void record_last_mem_set_info PROTO ((rtx)); | |
571 | static void record_last_set_info PROTO ((rtx, rtx)); | |
572 | static void compute_hash_table PROTO ((rtx, int)); | |
573 | static void alloc_set_hash_table PROTO ((int)); | |
574 | static void free_set_hash_table PROTO ((void)); | |
575 | static void compute_set_hash_table PROTO ((rtx)); | |
576 | static void alloc_expr_hash_table PROTO ((int)); | |
577 | static void free_expr_hash_table PROTO ((void)); | |
578 | static void compute_expr_hash_table PROTO ((rtx)); | |
579 | static void dump_hash_table PROTO ((FILE *, char *, struct expr **, int, int)); | |
580 | static struct expr *lookup_expr PROTO ((rtx)); | |
581 | static struct expr *lookup_set PROTO ((int, rtx)); | |
582 | static struct expr *next_set PROTO ((int, struct expr *)); | |
583 | static void reset_opr_set_tables PROTO ((void)); | |
584 | static int oprs_not_set_p PROTO ((rtx, rtx)); | |
585 | static void mark_call PROTO ((rtx, rtx)); | |
586 | static void mark_set PROTO ((rtx, rtx)); | |
587 | static void mark_clobber PROTO ((rtx, rtx)); | |
588 | static void mark_oprs_set PROTO ((rtx)); | |
589 | ||
590 | static void alloc_rd_mem PROTO ((int, int)); | |
591 | static void free_rd_mem PROTO ((void)); | |
592 | static void compute_kill_rd PROTO ((void)); | |
593 | static void handle_rd_kill_set PROTO ((rtx, int, int)); | |
594 | static void compute_rd PROTO ((void)); | |
50b2596f | 595 | extern void dump_rd_table PROTO ((FILE *, char *, sbitmap *)); |
7506f491 DE |
596 | |
597 | static void alloc_avail_expr_mem PROTO ((int, int)); | |
598 | static void free_avail_expr_mem PROTO ((void)); | |
599 | static void compute_ae_gen PROTO ((void)); | |
600 | static void compute_ae_kill PROTO ((void)); | |
601 | static int expr_killed_p PROTO ((rtx, int)); | |
602 | static void compute_available PROTO ((void)); | |
603 | ||
604 | static int expr_reaches_here_p PROTO ((struct occr *, struct expr *, | |
605 | int, int, char *)); | |
606 | static rtx computing_insn PROTO ((struct expr *, rtx)); | |
607 | static int def_reaches_here_p PROTO ((rtx, rtx)); | |
608 | static int can_disregard_other_sets PROTO ((struct reg_set **, rtx, int)); | |
609 | static int handle_avail_expr PROTO ((rtx, struct expr *)); | |
610 | static int classic_gcse PROTO ((void)); | |
611 | static int one_classic_gcse_pass PROTO ((rtx, int)); | |
612 | ||
613 | static void alloc_cprop_mem PROTO ((int, int)); | |
614 | static void free_cprop_mem PROTO ((void)); | |
50b2596f | 615 | extern void dump_cprop_data PROTO ((FILE *)); |
7506f491 DE |
616 | static void compute_transp PROTO ((rtx, int, sbitmap *, int)); |
617 | static void compute_cprop_local_properties PROTO ((void)); | |
618 | static void compute_cprop_avinout PROTO ((void)); | |
619 | static void compute_cprop_data PROTO ((void)); | |
620 | static void find_used_regs PROTO ((rtx)); | |
621 | static int try_replace_reg PROTO ((rtx, rtx, rtx)); | |
622 | static struct expr *find_avail_set PROTO ((int, rtx)); | |
623 | static int cprop_insn PROTO ((rtx)); | |
624 | static int cprop PROTO ((void)); | |
625 | static int one_cprop_pass PROTO ((rtx, int)); | |
626 | ||
627 | static void alloc_pre_mem PROTO ((int, int)); | |
628 | static void free_pre_mem PROTO ((void)); | |
50b2596f | 629 | extern void dump_pre_data PROTO ((FILE *)); |
7506f491 DE |
630 | static void compute_pre_local_properties PROTO ((void)); |
631 | static void compute_pre_avinout PROTO ((void)); | |
632 | static void compute_pre_antinout PROTO ((void)); | |
633 | static void compute_pre_pavinout PROTO ((void)); | |
634 | static void compute_pre_ppinout PROTO ((void)); | |
635 | static void compute_pre_data PROTO ((void)); | |
636 | static int pre_expr_reaches_here_p PROTO ((struct occr *, struct expr *, | |
637 | int, char *)); | |
638 | static void pre_insert_insn PROTO ((struct expr *, int)); | |
639 | static void pre_insert PROTO ((struct expr **)); | |
640 | static void pre_insert_copy_insn PROTO ((struct expr *, rtx)); | |
641 | static void pre_insert_copies PROTO ((void)); | |
642 | static int pre_delete PROTO ((void)); | |
643 | static int pre_gcse PROTO ((void)); | |
644 | static int one_pre_gcse_pass PROTO ((rtx, int)); | |
aeb2f500 JW |
645 | |
646 | static void add_label_notes PROTO ((rtx, rtx)); | |
7506f491 DE |
647 | \f |
648 | /* Entry point for global common subexpression elimination. | |
649 | F is the first instruction in the function. */ | |
650 | ||
651 | void | |
652 | gcse_main (f, file) | |
653 | rtx f; | |
654 | FILE *file; | |
655 | { | |
656 | int changed, pass; | |
657 | /* Bytes used at start of pass. */ | |
658 | int initial_bytes_used; | |
659 | /* Maximum number of bytes used by a pass. */ | |
660 | int max_pass_bytes; | |
661 | /* Point to release obstack data from for each pass. */ | |
662 | char *gcse_obstack_bottom; | |
663 | ||
664 | /* It's impossible to construct a correct control flow graph in the | |
665 | presense of setjmp, so just punt to be safe. */ | |
666 | if (current_function_calls_setjmp) | |
667 | return; | |
668 | ||
669 | /* For calling dump_foo fns from gdb. */ | |
670 | debug_stderr = stderr; | |
671 | ||
672 | max_gcse_regno = max_reg_num (); | |
9265dacf | 673 | find_basic_blocks (f, max_gcse_regno, file); |
7506f491 DE |
674 | |
675 | /* Return if there's nothing to do. */ | |
676 | if (n_basic_blocks <= 1) | |
677 | { | |
678 | /* Free storage allocated by find_basic_blocks. */ | |
679 | free_basic_block_vars (0); | |
680 | return; | |
681 | } | |
682 | ||
683 | /* See what modes support reg/reg copy operations. */ | |
684 | if (! can_copy_init_p) | |
685 | { | |
686 | compute_can_copy (); | |
687 | can_copy_init_p = 1; | |
688 | } | |
689 | ||
690 | gcc_obstack_init (&gcse_obstack); | |
691 | ||
692 | gcse_file = file; | |
693 | ||
694 | /* Allocate and compute predecessors/successors. */ | |
695 | ||
696 | s_preds = (int_list_ptr *) alloca (n_basic_blocks * sizeof (int_list_ptr)); | |
697 | s_succs = (int_list_ptr *) alloca (n_basic_blocks * sizeof (int_list_ptr)); | |
698 | num_preds = (int *) alloca (n_basic_blocks * sizeof (int)); | |
699 | num_succs = (int *) alloca (n_basic_blocks * sizeof (int)); | |
700 | bytes_used = 4 * n_basic_blocks * sizeof (int_list_ptr); | |
701 | compute_preds_succs (s_preds, s_succs, num_preds, num_succs); | |
702 | ||
703 | if (file) | |
421382ac | 704 | dump_bb_data (file, s_preds, s_succs, 0); |
7506f491 DE |
705 | |
706 | /* Record where pseudo-registers are set. | |
707 | This data is kept accurate during each pass. | |
708 | ??? We could also record hard-reg and memory information here | |
709 | [since it's unchanging], however it is currently done during | |
710 | hash table computation. */ | |
711 | ||
712 | alloc_reg_set_mem (max_gcse_regno); | |
713 | compute_sets (f); | |
714 | ||
715 | pass = 0; | |
716 | initial_bytes_used = bytes_used; | |
717 | max_pass_bytes = 0; | |
718 | gcse_obstack_bottom = gcse_alloc (1); | |
719 | changed = 1; | |
720 | while (changed && pass < MAX_PASSES) | |
721 | { | |
722 | changed = 0; | |
723 | if (file) | |
724 | fprintf (file, "GCSE pass %d\n\n", pass + 1); | |
725 | ||
726 | /* Initialize bytes_used to the space for the pred/succ lists, | |
727 | and the reg_set_table data. */ | |
728 | bytes_used = initial_bytes_used; | |
729 | ||
730 | /* Each pass may create new registers, so recalculate each time. */ | |
731 | max_gcse_regno = max_reg_num (); | |
732 | ||
733 | alloc_gcse_mem (f); | |
734 | ||
735 | changed = one_cprop_pass (f, pass + 1); | |
736 | ||
737 | if (optimize_size) | |
738 | changed |= one_classic_gcse_pass (f, pass + 1); | |
739 | else | |
740 | changed |= one_pre_gcse_pass (f, pass + 1); | |
741 | ||
742 | if (max_pass_bytes < bytes_used) | |
743 | max_pass_bytes = bytes_used; | |
744 | ||
745 | free_gcse_mem (); | |
746 | ||
747 | if (file) | |
748 | { | |
749 | fprintf (file, "\n"); | |
750 | fflush (file); | |
751 | } | |
752 | obstack_free (&gcse_obstack, gcse_obstack_bottom); | |
753 | pass++; | |
754 | } | |
755 | ||
756 | /* If we're doing PRE, do one last pass of copy propagation. */ | |
757 | if (! optimize_size) | |
758 | { | |
759 | max_gcse_regno = max_reg_num (); | |
760 | alloc_gcse_mem (f); | |
761 | one_cprop_pass (f, pass + 1); | |
762 | free_gcse_mem (); | |
763 | } | |
764 | ||
765 | if (file) | |
766 | { | |
767 | fprintf (file, "GCSE of %s: %d basic blocks, ", | |
768 | current_function_name, n_basic_blocks); | |
769 | fprintf (file, "%d pass%s, %d bytes\n\n", | |
770 | pass, pass > 1 ? "es" : "", max_pass_bytes); | |
771 | } | |
772 | ||
773 | /* Free our obstack. */ | |
774 | obstack_free (&gcse_obstack, NULL_PTR); | |
775 | /* Free reg_set_table. */ | |
776 | free_reg_set_mem (); | |
777 | /* Free storage used to record predecessor/successor data. */ | |
778 | free_bb_mem (); | |
779 | /* Free storage allocated by find_basic_blocks. */ | |
780 | free_basic_block_vars (0); | |
781 | } | |
782 | \f | |
783 | /* Misc. utilities. */ | |
784 | ||
785 | /* Compute which modes support reg/reg copy operations. */ | |
786 | ||
787 | static void | |
788 | compute_can_copy () | |
789 | { | |
790 | int i; | |
50b2596f | 791 | #ifndef AVOID_CCMODE_COPIES |
7506f491 | 792 | rtx reg,insn; |
50b2596f | 793 | #endif |
7506f491 DE |
794 | char *free_point = (char *) oballoc (1); |
795 | ||
796 | bzero (can_copy_p, NUM_MACHINE_MODES); | |
797 | ||
798 | start_sequence (); | |
799 | for (i = 0; i < NUM_MACHINE_MODES; i++) | |
800 | { | |
801 | switch (GET_MODE_CLASS (i)) | |
802 | { | |
803 | case MODE_CC : | |
804 | #ifdef AVOID_CCMODE_COPIES | |
805 | can_copy_p[i] = 0; | |
806 | #else | |
9e6a5703 JC |
807 | reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1); |
808 | insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg)); | |
7506f491 DE |
809 | if (recog (PATTERN (insn), insn, NULL_PTR) >= 0) |
810 | can_copy_p[i] = 1; | |
811 | #endif | |
812 | break; | |
813 | default : | |
814 | can_copy_p[i] = 1; | |
815 | break; | |
816 | } | |
817 | } | |
818 | end_sequence (); | |
819 | ||
820 | /* Free the objects we just allocated. */ | |
821 | obfree (free_point); | |
822 | } | |
823 | \f | |
824 | /* Cover function to xmalloc to record bytes allocated. */ | |
825 | ||
826 | static char * | |
827 | gmalloc (size) | |
828 | unsigned int size; | |
829 | { | |
830 | bytes_used += size; | |
831 | return xmalloc (size); | |
832 | } | |
833 | ||
834 | /* Cover function to xrealloc. | |
835 | We don't record the additional size since we don't know it. | |
836 | It won't affect memory usage stats much anyway. */ | |
837 | ||
838 | static char * | |
839 | grealloc (ptr, size) | |
840 | char *ptr; | |
841 | unsigned int size; | |
842 | { | |
843 | return xrealloc (ptr, size); | |
844 | } | |
845 | ||
846 | /* Cover function to obstack_alloc. | |
847 | We don't need to record the bytes allocated here since | |
848 | obstack_chunk_alloc is set to gmalloc. */ | |
849 | ||
850 | static char * | |
851 | gcse_alloc (size) | |
852 | unsigned long size; | |
853 | { | |
854 | return (char *) obstack_alloc (&gcse_obstack, size); | |
855 | } | |
856 | ||
857 | /* Allocate memory for the cuid mapping array, | |
858 | and reg/memory set tracking tables. | |
859 | ||
860 | This is called at the start of each pass. */ | |
861 | ||
862 | static void | |
863 | alloc_gcse_mem (f) | |
864 | rtx f; | |
865 | { | |
866 | int i,n; | |
867 | rtx insn; | |
868 | ||
869 | /* Find the largest UID and create a mapping from UIDs to CUIDs. | |
870 | CUIDs are like UIDs except they increase monotonically, have no gaps, | |
871 | and only apply to real insns. */ | |
872 | ||
873 | max_uid = get_max_uid (); | |
874 | n = (max_uid + 1) * sizeof (int); | |
875 | uid_cuid = (int *) gmalloc (n); | |
876 | bzero ((char *) uid_cuid, n); | |
877 | for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) | |
878 | { | |
879 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
880 | INSN_CUID (insn) = i++; | |
881 | else | |
882 | INSN_CUID (insn) = i; | |
883 | } | |
884 | ||
885 | /* Create a table mapping cuids to insns. */ | |
886 | ||
887 | max_cuid = i; | |
888 | n = (max_cuid + 1) * sizeof (rtx); | |
889 | cuid_insn = (rtx *) gmalloc (n); | |
890 | bzero ((char *) cuid_insn, n); | |
891 | for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) | |
892 | { | |
893 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
894 | { | |
895 | CUID_INSN (i) = insn; | |
896 | i++; | |
897 | } | |
898 | } | |
899 | ||
900 | /* Allocate vars to track sets of regs. */ | |
901 | ||
902 | reg_set_bitmap = (sbitmap) sbitmap_alloc (max_gcse_regno); | |
903 | ||
904 | /* Allocate vars to track sets of regs, memory per block. */ | |
905 | ||
906 | reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (n_basic_blocks, | |
907 | max_gcse_regno); | |
908 | mem_set_in_block = (char *) gmalloc (n_basic_blocks); | |
909 | } | |
910 | ||
911 | /* Free memory allocated by alloc_gcse_mem. */ | |
912 | ||
913 | static void | |
914 | free_gcse_mem () | |
915 | { | |
916 | free (uid_cuid); | |
917 | free (cuid_insn); | |
918 | ||
919 | free (reg_set_bitmap); | |
920 | ||
921 | free (reg_set_in_block); | |
922 | free (mem_set_in_block); | |
923 | } | |
924 | ||
50b2596f | 925 | void |
7506f491 DE |
926 | dump_cuid_table (file) |
927 | FILE *file; | |
928 | { | |
eb516666 | 929 | int i; |
7506f491 DE |
930 | |
931 | fprintf (file, "CUID table\n"); | |
eb516666 | 932 | for (i = 0; i < max_cuid; i++) |
7506f491 DE |
933 | { |
934 | rtx insn = CUID_INSN (i); | |
eb516666 | 935 | if (i != 0 && i % 10 == 0) |
7506f491 DE |
936 | fprintf (file, "\n"); |
937 | if (insn != NULL) | |
938 | fprintf (file, " %d", INSN_UID (insn)); | |
939 | } | |
940 | fprintf (file, "\n\n"); | |
941 | } | |
942 | \f | |
943 | /* Register set information. | |
944 | ||
945 | `reg_set_table' records where each register is set or otherwise | |
946 | modified. */ | |
947 | ||
948 | static struct obstack reg_set_obstack; | |
949 | ||
950 | static void | |
951 | alloc_reg_set_mem (n_regs) | |
952 | int n_regs; | |
953 | { | |
954 | int n; | |
955 | ||
956 | reg_set_table_size = n_regs + REG_SET_TABLE_SLOP; | |
957 | n = reg_set_table_size * sizeof (struct reg_set *); | |
958 | reg_set_table = (struct reg_set **) gmalloc (n); | |
959 | bzero ((char *) reg_set_table, n); | |
960 | ||
961 | gcc_obstack_init (®_set_obstack); | |
962 | } | |
963 | ||
964 | static void | |
965 | free_reg_set_mem () | |
966 | { | |
967 | free (reg_set_table); | |
968 | obstack_free (®_set_obstack, NULL_PTR); | |
969 | } | |
970 | ||
971 | /* Record REGNO in the reg_set table. */ | |
972 | ||
973 | static void | |
974 | record_one_set (regno, insn) | |
975 | int regno; | |
976 | rtx insn; | |
977 | { | |
978 | /* allocate a new reg_set element and link it onto the list */ | |
979 | struct reg_set *new_reg_info, *reg_info_ptr1, *reg_info_ptr2; | |
980 | ||
981 | /* If the table isn't big enough, enlarge it. */ | |
982 | if (regno >= reg_set_table_size) | |
983 | { | |
984 | int new_size = regno + REG_SET_TABLE_SLOP; | |
985 | reg_set_table = (struct reg_set **) | |
986 | grealloc ((char *) reg_set_table, | |
987 | new_size * sizeof (struct reg_set *)); | |
988 | bzero ((char *) (reg_set_table + reg_set_table_size), | |
989 | (new_size - reg_set_table_size) * sizeof (struct reg_set *)); | |
990 | reg_set_table_size = new_size; | |
991 | } | |
992 | ||
993 | new_reg_info = (struct reg_set *) obstack_alloc (®_set_obstack, | |
994 | sizeof (struct reg_set)); | |
995 | bytes_used += sizeof (struct reg_set); | |
996 | new_reg_info->insn = insn; | |
997 | new_reg_info->next = NULL; | |
998 | if (reg_set_table[regno] == NULL) | |
999 | reg_set_table[regno] = new_reg_info; | |
1000 | else | |
1001 | { | |
1002 | reg_info_ptr1 = reg_info_ptr2 = reg_set_table[regno]; | |
1003 | /* ??? One could keep a "last" pointer to speed this up. */ | |
1004 | while (reg_info_ptr1 != NULL) | |
1005 | { | |
1006 | reg_info_ptr2 = reg_info_ptr1; | |
1007 | reg_info_ptr1 = reg_info_ptr1->next; | |
1008 | } | |
1009 | reg_info_ptr2->next = new_reg_info; | |
1010 | } | |
1011 | } | |
1012 | ||
1013 | /* For communication between next two functions (via note_stores). */ | |
1014 | static rtx record_set_insn; | |
1015 | ||
1016 | /* Called from compute_sets via note_stores to handle one | |
1017 | SET or CLOBBER in an insn. */ | |
1018 | ||
1019 | static void | |
1020 | record_set_info (dest, setter) | |
50b2596f | 1021 | rtx dest, setter ATTRIBUTE_UNUSED; |
7506f491 DE |
1022 | { |
1023 | if (GET_CODE (dest) == SUBREG) | |
1024 | dest = SUBREG_REG (dest); | |
1025 | ||
1026 | if (GET_CODE (dest) == REG) | |
1027 | { | |
1028 | if (REGNO (dest) >= FIRST_PSEUDO_REGISTER) | |
1029 | record_one_set (REGNO (dest), record_set_insn); | |
1030 | } | |
1031 | } | |
1032 | ||
1033 | /* Scan the function and record each set of each pseudo-register. | |
1034 | ||
1035 | This is called once, at the start of the gcse pass. | |
1036 | See the comments for `reg_set_table' for further docs. */ | |
1037 | ||
1038 | static void | |
1039 | compute_sets (f) | |
1040 | rtx f; | |
1041 | { | |
1042 | rtx insn = f; | |
1043 | ||
1044 | while (insn) | |
1045 | { | |
1046 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
1047 | { | |
1048 | record_set_insn = insn; | |
1049 | note_stores (PATTERN (insn), record_set_info); | |
1050 | } | |
1051 | insn = NEXT_INSN (insn); | |
1052 | } | |
1053 | } | |
1054 | \f | |
1055 | /* Hash table support. */ | |
1056 | ||
b86ba9c8 GK |
1057 | #define NEVER_SET -1 |
1058 | ||
7506f491 | 1059 | /* For each register, the cuid of the first/last insn in the block to set it, |
e7d99f1e | 1060 | or -1 if not set. */ |
7506f491 DE |
1061 | static int *reg_first_set; |
1062 | static int *reg_last_set; | |
1063 | ||
1064 | /* While computing "first/last set" info, this is the CUID of first/last insn | |
e7d99f1e | 1065 | to set memory or -1 if not set. `mem_last_set' is also used when |
7506f491 DE |
1066 | performing GCSE to record whether memory has been set since the beginning |
1067 | of the block. | |
1068 | Note that handling of memory is very simple, we don't make any attempt | |
1069 | to optimize things (later). */ | |
1070 | static int mem_first_set; | |
1071 | static int mem_last_set; | |
1072 | ||
1073 | /* Set the appropriate bit in `rd_gen' [the gen for reaching defs] if the | |
1074 | register set in this insn is not set after this insn in this block. */ | |
1075 | ||
1076 | static void | |
1077 | maybe_set_rd_gen (regno, insn) | |
1078 | int regno; | |
1079 | rtx insn; | |
1080 | { | |
1081 | if (reg_last_set[regno] <= INSN_CUID (insn)) | |
1082 | SET_BIT (rd_gen[BLOCK_NUM (insn)], INSN_CUID (insn)); | |
1083 | } | |
1084 | ||
1085 | /* Perform a quick check whether X, the source of a set, is something | |
1086 | we want to consider for GCSE. */ | |
1087 | ||
1088 | static int | |
1089 | want_to_gcse_p (x) | |
1090 | rtx x; | |
1091 | { | |
1092 | enum rtx_code code = GET_CODE (x); | |
1093 | ||
1094 | switch (code) | |
1095 | { | |
1096 | case REG: | |
1097 | case SUBREG: | |
1098 | case CONST_INT: | |
1099 | case CONST_DOUBLE: | |
1100 | case CALL: | |
1101 | return 0; | |
1102 | ||
1103 | default: | |
1104 | break; | |
1105 | } | |
1106 | ||
1107 | return 1; | |
1108 | } | |
1109 | ||
1110 | /* Return non-zero if the operands of expression X are unchanged from the | |
1111 | start of INSN's basic block up to but not including INSN (if AVAIL_P == 0), | |
1112 | or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */ | |
1113 | ||
1114 | static int | |
1115 | oprs_unchanged_p (x, insn, avail_p) | |
1116 | rtx x, insn; | |
1117 | int avail_p; | |
1118 | { | |
1119 | int i; | |
1120 | enum rtx_code code; | |
1121 | char *fmt; | |
1122 | ||
1123 | /* repeat is used to turn tail-recursion into iteration. */ | |
1124 | repeat: | |
1125 | ||
1126 | if (x == 0) | |
1127 | return 1; | |
1128 | ||
1129 | code = GET_CODE (x); | |
1130 | switch (code) | |
1131 | { | |
1132 | case REG: | |
1133 | if (avail_p) | |
b86ba9c8 | 1134 | return (reg_last_set[REGNO (x)] == NEVER_SET |
7506f491 DE |
1135 | || reg_last_set[REGNO (x)] < INSN_CUID (insn)); |
1136 | else | |
b86ba9c8 | 1137 | return (reg_first_set[REGNO (x)] == NEVER_SET |
7506f491 DE |
1138 | || reg_first_set[REGNO (x)] >= INSN_CUID (insn)); |
1139 | ||
1140 | case MEM: | |
1141 | if (avail_p) | |
1142 | { | |
b86ba9c8 | 1143 | if (mem_last_set != NEVER_SET |
7506f491 DE |
1144 | && mem_last_set >= INSN_CUID (insn)) |
1145 | return 0; | |
1146 | } | |
1147 | else | |
1148 | { | |
b86ba9c8 | 1149 | if (mem_first_set != NEVER_SET |
7506f491 DE |
1150 | && mem_first_set < INSN_CUID (insn)) |
1151 | return 0; | |
1152 | } | |
1153 | x = XEXP (x, 0); | |
1154 | goto repeat; | |
1155 | ||
1156 | case PRE_DEC: | |
1157 | case PRE_INC: | |
1158 | case POST_DEC: | |
1159 | case POST_INC: | |
1160 | return 0; | |
1161 | ||
1162 | case PC: | |
1163 | case CC0: /*FIXME*/ | |
1164 | case CONST: | |
1165 | case CONST_INT: | |
1166 | case CONST_DOUBLE: | |
1167 | case SYMBOL_REF: | |
1168 | case LABEL_REF: | |
1169 | case ADDR_VEC: | |
1170 | case ADDR_DIFF_VEC: | |
1171 | return 1; | |
1172 | ||
1173 | default: | |
1174 | break; | |
1175 | } | |
1176 | ||
1177 | i = GET_RTX_LENGTH (code) - 1; | |
1178 | fmt = GET_RTX_FORMAT (code); | |
1179 | for (; i >= 0; i--) | |
1180 | { | |
1181 | if (fmt[i] == 'e') | |
1182 | { | |
1183 | rtx tem = XEXP (x, i); | |
1184 | ||
1185 | /* If we are about to do the last recursive call | |
1186 | needed at this level, change it into iteration. | |
1187 | This function is called enough to be worth it. */ | |
1188 | if (i == 0) | |
1189 | { | |
1190 | x = tem; | |
1191 | goto repeat; | |
1192 | } | |
1193 | if (! oprs_unchanged_p (tem, insn, avail_p)) | |
1194 | return 0; | |
1195 | } | |
1196 | else if (fmt[i] == 'E') | |
1197 | { | |
1198 | int j; | |
1199 | for (j = 0; j < XVECLEN (x, i); j++) | |
1200 | { | |
1201 | if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p)) | |
1202 | return 0; | |
1203 | } | |
1204 | } | |
1205 | } | |
1206 | ||
1207 | return 1; | |
1208 | } | |
1209 | ||
1210 | /* Return non-zero if the operands of expression X are unchanged from | |
1211 | the start of INSN's basic block up to but not including INSN. */ | |
1212 | ||
1213 | static int | |
1214 | oprs_anticipatable_p (x, insn) | |
1215 | rtx x, insn; | |
1216 | { | |
1217 | return oprs_unchanged_p (x, insn, 0); | |
1218 | } | |
1219 | ||
1220 | /* Return non-zero if the operands of expression X are unchanged from | |
1221 | INSN to the end of INSN's basic block. */ | |
1222 | ||
1223 | static int | |
1224 | oprs_available_p (x, insn) | |
1225 | rtx x, insn; | |
1226 | { | |
1227 | return oprs_unchanged_p (x, insn, 1); | |
1228 | } | |
1229 | ||
1230 | /* Hash expression X. | |
1231 | MODE is only used if X is a CONST_INT. | |
1232 | A boolean indicating if a volatile operand is found or if the expression | |
1233 | contains something we don't want to insert in the table is stored in | |
1234 | DO_NOT_RECORD_P. | |
1235 | ||
1236 | ??? One might want to merge this with canon_hash. Later. */ | |
1237 | ||
1238 | static unsigned int | |
1239 | hash_expr (x, mode, do_not_record_p, hash_table_size) | |
1240 | rtx x; | |
1241 | enum machine_mode mode; | |
1242 | int *do_not_record_p; | |
1243 | int hash_table_size; | |
1244 | { | |
1245 | unsigned int hash; | |
1246 | ||
1247 | *do_not_record_p = 0; | |
1248 | ||
1249 | hash = hash_expr_1 (x, mode, do_not_record_p); | |
1250 | return hash % hash_table_size; | |
1251 | } | |
1252 | ||
1253 | /* Subroutine of hash_expr to do the actual work. */ | |
1254 | ||
1255 | static unsigned int | |
1256 | hash_expr_1 (x, mode, do_not_record_p) | |
1257 | rtx x; | |
1258 | enum machine_mode mode; | |
1259 | int *do_not_record_p; | |
1260 | { | |
1261 | int i, j; | |
1262 | unsigned hash = 0; | |
1263 | enum rtx_code code; | |
1264 | char *fmt; | |
1265 | ||
1266 | /* repeat is used to turn tail-recursion into iteration. */ | |
1267 | repeat: | |
1268 | ||
1269 | if (x == 0) | |
1270 | return hash; | |
1271 | ||
1272 | code = GET_CODE (x); | |
1273 | switch (code) | |
1274 | { | |
1275 | case REG: | |
1276 | { | |
1277 | register int regno = REGNO (x); | |
1278 | hash += ((unsigned) REG << 7) + regno; | |
1279 | return hash; | |
1280 | } | |
1281 | ||
1282 | case CONST_INT: | |
1283 | { | |
1284 | unsigned HOST_WIDE_INT tem = INTVAL (x); | |
1285 | hash += ((unsigned) CONST_INT << 7) + (unsigned) mode + tem; | |
1286 | return hash; | |
1287 | } | |
1288 | ||
1289 | case CONST_DOUBLE: | |
1290 | /* This is like the general case, except that it only counts | |
1291 | the integers representing the constant. */ | |
1292 | hash += (unsigned) code + (unsigned) GET_MODE (x); | |
1293 | if (GET_MODE (x) != VOIDmode) | |
1294 | for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++) | |
1295 | { | |
1296 | unsigned tem = XINT (x, i); | |
1297 | hash += tem; | |
1298 | } | |
1299 | else | |
1300 | hash += ((unsigned) CONST_DOUBLE_LOW (x) | |
1301 | + (unsigned) CONST_DOUBLE_HIGH (x)); | |
1302 | return hash; | |
1303 | ||
1304 | /* Assume there is only one rtx object for any given label. */ | |
1305 | case LABEL_REF: | |
1306 | /* We don't hash on the address of the CODE_LABEL to avoid bootstrap | |
1307 | differences and differences between each stage's debugging dumps. */ | |
1308 | hash += ((unsigned) LABEL_REF << 7) + CODE_LABEL_NUMBER (XEXP (x, 0)); | |
1309 | return hash; | |
1310 | ||
1311 | case SYMBOL_REF: | |
1312 | { | |
1313 | /* Don't hash on the symbol's address to avoid bootstrap differences. | |
1314 | Different hash values may cause expressions to be recorded in | |
1315 | different orders and thus different registers to be used in the | |
1316 | final assembler. This also avoids differences in the dump files | |
1317 | between various stages. */ | |
1318 | unsigned int h = 0; | |
1319 | unsigned char *p = (unsigned char *) XSTR (x, 0); | |
1320 | while (*p) | |
1321 | h += (h << 7) + *p++; /* ??? revisit */ | |
1322 | hash += ((unsigned) SYMBOL_REF << 7) + h; | |
1323 | return hash; | |
1324 | } | |
1325 | ||
1326 | case MEM: | |
1327 | if (MEM_VOLATILE_P (x)) | |
1328 | { | |
1329 | *do_not_record_p = 1; | |
1330 | return 0; | |
1331 | } | |
1332 | hash += (unsigned) MEM; | |
1333 | x = XEXP (x, 0); | |
1334 | goto repeat; | |
1335 | ||
1336 | case PRE_DEC: | |
1337 | case PRE_INC: | |
1338 | case POST_DEC: | |
1339 | case POST_INC: | |
1340 | case PC: | |
1341 | case CC0: | |
1342 | case CALL: | |
1343 | case UNSPEC_VOLATILE: | |
1344 | *do_not_record_p = 1; | |
1345 | return 0; | |
1346 | ||
1347 | case ASM_OPERANDS: | |
1348 | if (MEM_VOLATILE_P (x)) | |
1349 | { | |
1350 | *do_not_record_p = 1; | |
1351 | return 0; | |
1352 | } | |
1353 | ||
1354 | default: | |
1355 | break; | |
1356 | } | |
1357 | ||
1358 | i = GET_RTX_LENGTH (code) - 1; | |
1359 | hash += (unsigned) code + (unsigned) GET_MODE (x); | |
1360 | fmt = GET_RTX_FORMAT (code); | |
1361 | for (; i >= 0; i--) | |
1362 | { | |
1363 | if (fmt[i] == 'e') | |
1364 | { | |
1365 | rtx tem = XEXP (x, i); | |
1366 | ||
1367 | /* If we are about to do the last recursive call | |
1368 | needed at this level, change it into iteration. | |
1369 | This function is called enough to be worth it. */ | |
1370 | if (i == 0) | |
1371 | { | |
1372 | x = tem; | |
1373 | goto repeat; | |
1374 | } | |
1375 | hash += hash_expr_1 (tem, 0, do_not_record_p); | |
1376 | if (*do_not_record_p) | |
1377 | return 0; | |
1378 | } | |
1379 | else if (fmt[i] == 'E') | |
1380 | for (j = 0; j < XVECLEN (x, i); j++) | |
1381 | { | |
1382 | hash += hash_expr_1 (XVECEXP (x, i, j), 0, do_not_record_p); | |
1383 | if (*do_not_record_p) | |
1384 | return 0; | |
1385 | } | |
1386 | else if (fmt[i] == 's') | |
1387 | { | |
1388 | register unsigned char *p = (unsigned char *) XSTR (x, i); | |
1389 | if (p) | |
1390 | while (*p) | |
1391 | hash += *p++; | |
1392 | } | |
1393 | else if (fmt[i] == 'i') | |
1394 | { | |
1395 | register unsigned tem = XINT (x, i); | |
1396 | hash += tem; | |
1397 | } | |
1398 | else | |
1399 | abort (); | |
1400 | } | |
1401 | ||
1402 | return hash; | |
1403 | } | |
1404 | ||
1405 | /* Hash a set of register REGNO. | |
1406 | ||
1407 | Sets are hashed on the register that is set. | |
1408 | This simplifies the PRE copy propagation code. | |
1409 | ||
1410 | ??? May need to make things more elaborate. Later, as necessary. */ | |
1411 | ||
1412 | static unsigned int | |
1413 | hash_set (regno, hash_table_size) | |
1414 | int regno; | |
1415 | int hash_table_size; | |
1416 | { | |
1417 | unsigned int hash; | |
1418 | ||
1419 | hash = regno; | |
1420 | return hash % hash_table_size; | |
1421 | } | |
1422 | ||
1423 | /* Return non-zero if exp1 is equivalent to exp2. | |
1424 | ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */ | |
1425 | ||
1426 | static int | |
1427 | expr_equiv_p (x, y) | |
1428 | rtx x, y; | |
1429 | { | |
1430 | register int i, j; | |
1431 | register enum rtx_code code; | |
1432 | register char *fmt; | |
1433 | ||
1434 | if (x == y) | |
1435 | return 1; | |
1436 | if (x == 0 || y == 0) | |
1437 | return x == y; | |
1438 | ||
1439 | code = GET_CODE (x); | |
1440 | if (code != GET_CODE (y)) | |
1441 | return 0; | |
1442 | ||
1443 | /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */ | |
1444 | if (GET_MODE (x) != GET_MODE (y)) | |
1445 | return 0; | |
1446 | ||
1447 | switch (code) | |
1448 | { | |
1449 | case PC: | |
1450 | case CC0: | |
1451 | return x == y; | |
1452 | ||
1453 | case CONST_INT: | |
1454 | return INTVAL (x) == INTVAL (y); | |
1455 | ||
1456 | case LABEL_REF: | |
1457 | return XEXP (x, 0) == XEXP (y, 0); | |
1458 | ||
1459 | case SYMBOL_REF: | |
1460 | return XSTR (x, 0) == XSTR (y, 0); | |
1461 | ||
1462 | case REG: | |
1463 | return REGNO (x) == REGNO (y); | |
1464 | ||
1465 | /* For commutative operations, check both orders. */ | |
1466 | case PLUS: | |
1467 | case MULT: | |
1468 | case AND: | |
1469 | case IOR: | |
1470 | case XOR: | |
1471 | case NE: | |
1472 | case EQ: | |
1473 | return ((expr_equiv_p (XEXP (x, 0), XEXP (y, 0)) | |
1474 | && expr_equiv_p (XEXP (x, 1), XEXP (y, 1))) | |
1475 | || (expr_equiv_p (XEXP (x, 0), XEXP (y, 1)) | |
1476 | && expr_equiv_p (XEXP (x, 1), XEXP (y, 0)))); | |
1477 | ||
1478 | default: | |
1479 | break; | |
1480 | } | |
1481 | ||
1482 | /* Compare the elements. If any pair of corresponding elements | |
1483 | fail to match, return 0 for the whole thing. */ | |
1484 | ||
1485 | fmt = GET_RTX_FORMAT (code); | |
1486 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
1487 | { | |
1488 | switch (fmt[i]) | |
1489 | { | |
1490 | case 'e': | |
1491 | if (! expr_equiv_p (XEXP (x, i), XEXP (y, i))) | |
1492 | return 0; | |
1493 | break; | |
1494 | ||
1495 | case 'E': | |
1496 | if (XVECLEN (x, i) != XVECLEN (y, i)) | |
1497 | return 0; | |
1498 | for (j = 0; j < XVECLEN (x, i); j++) | |
1499 | if (! expr_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j))) | |
1500 | return 0; | |
1501 | break; | |
1502 | ||
1503 | case 's': | |
1504 | if (strcmp (XSTR (x, i), XSTR (y, i))) | |
1505 | return 0; | |
1506 | break; | |
1507 | ||
1508 | case 'i': | |
1509 | if (XINT (x, i) != XINT (y, i)) | |
1510 | return 0; | |
1511 | break; | |
1512 | ||
1513 | case 'w': | |
1514 | if (XWINT (x, i) != XWINT (y, i)) | |
1515 | return 0; | |
1516 | break; | |
1517 | ||
1518 | case '0': | |
1519 | break; | |
1520 | ||
1521 | default: | |
1522 | abort (); | |
1523 | } | |
1524 | } | |
1525 | ||
1526 | return 1; | |
1527 | } | |
1528 | ||
1529 | /* Insert expression X in INSN in the hash table. | |
1530 | If it is already present, record it as the last occurrence in INSN's | |
1531 | basic block. | |
1532 | ||
1533 | MODE is the mode of the value X is being stored into. | |
1534 | It is only used if X is a CONST_INT. | |
1535 | ||
1536 | ANTIC_P is non-zero if X is an anticipatable expression. | |
1537 | AVAIL_P is non-zero if X is an available expression. */ | |
1538 | ||
1539 | static void | |
1540 | insert_expr_in_table (x, mode, insn, antic_p, avail_p) | |
1541 | rtx x; | |
1542 | enum machine_mode mode; | |
1543 | rtx insn; | |
1544 | int antic_p, avail_p; | |
1545 | { | |
1546 | int found, do_not_record_p; | |
1547 | unsigned int hash; | |
1548 | struct expr *cur_expr, *last_expr = NULL; | |
1549 | struct occr *antic_occr, *avail_occr; | |
1550 | struct occr *last_occr = NULL; | |
1551 | ||
1552 | hash = hash_expr (x, mode, &do_not_record_p, expr_hash_table_size); | |
1553 | ||
1554 | /* Do not insert expression in table if it contains volatile operands, | |
1555 | or if hash_expr determines the expression is something we don't want | |
1556 | to or can't handle. */ | |
1557 | if (do_not_record_p) | |
1558 | return; | |
1559 | ||
1560 | cur_expr = expr_hash_table[hash]; | |
1561 | found = 0; | |
1562 | ||
1563 | while (cur_expr && ! (found = expr_equiv_p (cur_expr->expr, x))) | |
1564 | { | |
1565 | /* If the expression isn't found, save a pointer to the end of | |
1566 | the list. */ | |
1567 | last_expr = cur_expr; | |
1568 | cur_expr = cur_expr->next_same_hash; | |
1569 | } | |
1570 | ||
1571 | if (! found) | |
1572 | { | |
1573 | cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr)); | |
1574 | bytes_used += sizeof (struct expr); | |
1575 | if (expr_hash_table[hash] == NULL) | |
1576 | { | |
1577 | /* This is the first pattern that hashed to this index. */ | |
1578 | expr_hash_table[hash] = cur_expr; | |
1579 | } | |
1580 | else | |
1581 | { | |
1582 | /* Add EXPR to end of this hash chain. */ | |
1583 | last_expr->next_same_hash = cur_expr; | |
1584 | } | |
1585 | /* Set the fields of the expr element. */ | |
1586 | cur_expr->expr = x; | |
1587 | cur_expr->bitmap_index = n_exprs++; | |
1588 | cur_expr->next_same_hash = NULL; | |
1589 | cur_expr->antic_occr = NULL; | |
1590 | cur_expr->avail_occr = NULL; | |
1591 | } | |
1592 | ||
1593 | /* Now record the occurrence(s). */ | |
1594 | ||
1595 | if (antic_p) | |
1596 | { | |
1597 | antic_occr = cur_expr->antic_occr; | |
1598 | ||
1599 | /* Search for another occurrence in the same basic block. */ | |
1600 | while (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn)) | |
1601 | { | |
1602 | /* If an occurrence isn't found, save a pointer to the end of | |
1603 | the list. */ | |
1604 | last_occr = antic_occr; | |
1605 | antic_occr = antic_occr->next; | |
1606 | } | |
1607 | ||
1608 | if (antic_occr) | |
1609 | { | |
1610 | /* Found another instance of the expression in the same basic block. | |
1611 | Prefer the currently recorded one. We want the first one in the | |
1612 | block and the block is scanned from start to end. */ | |
1613 | ; /* nothing to do */ | |
1614 | } | |
1615 | else | |
1616 | { | |
1617 | /* First occurrence of this expression in this basic block. */ | |
1618 | antic_occr = (struct occr *) gcse_alloc (sizeof (struct occr)); | |
1619 | bytes_used += sizeof (struct occr); | |
1620 | /* First occurrence of this expression in any block? */ | |
1621 | if (cur_expr->antic_occr == NULL) | |
1622 | cur_expr->antic_occr = antic_occr; | |
1623 | else | |
1624 | last_occr->next = antic_occr; | |
1625 | antic_occr->insn = insn; | |
1626 | antic_occr->next = NULL; | |
1627 | } | |
1628 | } | |
1629 | ||
1630 | if (avail_p) | |
1631 | { | |
1632 | avail_occr = cur_expr->avail_occr; | |
1633 | ||
1634 | /* Search for another occurrence in the same basic block. */ | |
1635 | while (avail_occr && BLOCK_NUM (avail_occr->insn) != BLOCK_NUM (insn)) | |
1636 | { | |
1637 | /* If an occurrence isn't found, save a pointer to the end of | |
1638 | the list. */ | |
1639 | last_occr = avail_occr; | |
1640 | avail_occr = avail_occr->next; | |
1641 | } | |
1642 | ||
1643 | if (avail_occr) | |
1644 | { | |
1645 | /* Found another instance of the expression in the same basic block. | |
1646 | Prefer this occurrence to the currently recorded one. We want | |
1647 | the last one in the block and the block is scanned from start | |
1648 | to end. */ | |
1649 | avail_occr->insn = insn; | |
1650 | } | |
1651 | else | |
1652 | { | |
1653 | /* First occurrence of this expression in this basic block. */ | |
1654 | avail_occr = (struct occr *) gcse_alloc (sizeof (struct occr)); | |
1655 | bytes_used += sizeof (struct occr); | |
1656 | /* First occurrence of this expression in any block? */ | |
1657 | if (cur_expr->avail_occr == NULL) | |
1658 | cur_expr->avail_occr = avail_occr; | |
1659 | else | |
1660 | last_occr->next = avail_occr; | |
1661 | avail_occr->insn = insn; | |
1662 | avail_occr->next = NULL; | |
1663 | } | |
1664 | } | |
1665 | } | |
1666 | ||
1667 | /* Insert pattern X in INSN in the hash table. | |
1668 | X is a SET of a reg to either another reg or a constant. | |
1669 | If it is already present, record it as the last occurrence in INSN's | |
1670 | basic block. */ | |
1671 | ||
1672 | static void | |
1673 | insert_set_in_table (x, insn) | |
1674 | rtx x; | |
1675 | rtx insn; | |
1676 | { | |
1677 | int found; | |
1678 | unsigned int hash; | |
1679 | struct expr *cur_expr, *last_expr = NULL; | |
1680 | struct occr *cur_occr, *last_occr = NULL; | |
1681 | ||
1682 | if (GET_CODE (x) != SET | |
1683 | || GET_CODE (SET_DEST (x)) != REG) | |
1684 | abort (); | |
1685 | ||
1686 | hash = hash_set (REGNO (SET_DEST (x)), set_hash_table_size); | |
1687 | ||
1688 | cur_expr = set_hash_table[hash]; | |
1689 | found = 0; | |
1690 | ||
1691 | while (cur_expr && ! (found = expr_equiv_p (cur_expr->expr, x))) | |
1692 | { | |
1693 | /* If the expression isn't found, save a pointer to the end of | |
1694 | the list. */ | |
1695 | last_expr = cur_expr; | |
1696 | cur_expr = cur_expr->next_same_hash; | |
1697 | } | |
1698 | ||
1699 | if (! found) | |
1700 | { | |
1701 | cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr)); | |
1702 | bytes_used += sizeof (struct expr); | |
1703 | if (set_hash_table[hash] == NULL) | |
1704 | { | |
1705 | /* This is the first pattern that hashed to this index. */ | |
1706 | set_hash_table[hash] = cur_expr; | |
1707 | } | |
1708 | else | |
1709 | { | |
1710 | /* Add EXPR to end of this hash chain. */ | |
1711 | last_expr->next_same_hash = cur_expr; | |
1712 | } | |
1713 | /* Set the fields of the expr element. | |
1714 | We must copy X because it can be modified when copy propagation is | |
1715 | performed on its operands. */ | |
1716 | /* ??? Should this go in a different obstack? */ | |
1717 | cur_expr->expr = copy_rtx (x); | |
1718 | cur_expr->bitmap_index = n_sets++; | |
1719 | cur_expr->next_same_hash = NULL; | |
1720 | cur_expr->antic_occr = NULL; | |
1721 | cur_expr->avail_occr = NULL; | |
1722 | } | |
1723 | ||
1724 | /* Now record the occurrence. */ | |
1725 | ||
1726 | cur_occr = cur_expr->avail_occr; | |
1727 | ||
1728 | /* Search for another occurrence in the same basic block. */ | |
1729 | while (cur_occr && BLOCK_NUM (cur_occr->insn) != BLOCK_NUM (insn)) | |
1730 | { | |
1731 | /* If an occurrence isn't found, save a pointer to the end of | |
1732 | the list. */ | |
1733 | last_occr = cur_occr; | |
1734 | cur_occr = cur_occr->next; | |
1735 | } | |
1736 | ||
1737 | if (cur_occr) | |
1738 | { | |
1739 | /* Found another instance of the expression in the same basic block. | |
1740 | Prefer this occurrence to the currently recorded one. We want | |
1741 | the last one in the block and the block is scanned from start | |
1742 | to end. */ | |
1743 | cur_occr->insn = insn; | |
1744 | } | |
1745 | else | |
1746 | { | |
1747 | /* First occurrence of this expression in this basic block. */ | |
1748 | cur_occr = (struct occr *) gcse_alloc (sizeof (struct occr)); | |
1749 | bytes_used += sizeof (struct occr); | |
1750 | /* First occurrence of this expression in any block? */ | |
1751 | if (cur_expr->avail_occr == NULL) | |
1752 | cur_expr->avail_occr = cur_occr; | |
1753 | else | |
1754 | last_occr->next = cur_occr; | |
1755 | cur_occr->insn = insn; | |
1756 | cur_occr->next = NULL; | |
1757 | } | |
1758 | } | |
1759 | ||
1760 | /* Scan pattern PAT of INSN and add an entry to the hash table. | |
1761 | If SET_P is non-zero, this is for the assignment hash table, | |
1762 | otherwise it is for the expression hash table. */ | |
1763 | ||
1764 | static void | |
1765 | hash_scan_set (pat, insn, set_p) | |
1766 | rtx pat, insn; | |
1767 | int set_p; | |
1768 | { | |
1769 | rtx src = SET_SRC (pat); | |
1770 | rtx dest = SET_DEST (pat); | |
1771 | ||
1772 | if (GET_CODE (src) == CALL) | |
1773 | hash_scan_call (src, insn); | |
1774 | ||
1775 | if (GET_CODE (dest) == REG) | |
1776 | { | |
1777 | int regno = REGNO (dest); | |
1778 | rtx tmp; | |
1779 | ||
1780 | /* Only record sets of pseudo-regs in the hash table. */ | |
1781 | if (! set_p | |
1782 | && regno >= FIRST_PSEUDO_REGISTER | |
1783 | /* Don't GCSE something if we can't do a reg/reg copy. */ | |
1784 | && can_copy_p [GET_MODE (dest)] | |
1785 | /* Is SET_SRC something we want to gcse? */ | |
1786 | && want_to_gcse_p (src)) | |
1787 | { | |
1788 | /* An expression is not anticipatable if its operands are | |
1789 | modified before this insn. */ | |
1790 | int antic_p = ! optimize_size && oprs_anticipatable_p (src, insn); | |
1791 | /* An expression is not available if its operands are | |
1792 | subsequently modified, including this insn. */ | |
1793 | int avail_p = oprs_available_p (src, insn); | |
1794 | insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p); | |
1795 | } | |
1796 | /* Record sets for constant/copy propagation. */ | |
1797 | else if (set_p | |
1798 | && regno >= FIRST_PSEUDO_REGISTER | |
1799 | && ((GET_CODE (src) == REG | |
1800 | && REGNO (src) >= FIRST_PSEUDO_REGISTER | |
1801 | && can_copy_p [GET_MODE (dest)]) | |
1802 | /* ??? CONST_INT:wip */ | |
1803 | || GET_CODE (src) == CONST_INT) | |
1804 | /* A copy is not available if its src or dest is subsequently | |
1805 | modified. Here we want to search from INSN+1 on, but | |
1806 | oprs_available_p searches from INSN on. */ | |
1807 | && (insn == BLOCK_END (BLOCK_NUM (insn)) | |
1808 | || ((tmp = next_nonnote_insn (insn)) != NULL_RTX | |
1809 | && oprs_available_p (pat, tmp)))) | |
1810 | insert_set_in_table (pat, insn); | |
1811 | } | |
1812 | ||
1813 | /* Check if first/last set in this block for classic gcse, | |
1814 | but not for copy/constant propagation. */ | |
1815 | if (optimize_size && !set_p) | |
1816 | ||
1817 | { | |
1818 | rtx dest = SET_DEST (pat); | |
1819 | ||
1820 | while (GET_CODE (dest) == SUBREG | |
1821 | || GET_CODE (dest) == ZERO_EXTRACT | |
1822 | || GET_CODE (dest) == SIGN_EXTRACT | |
1823 | || GET_CODE (dest) == STRICT_LOW_PART) | |
1824 | dest = XEXP (dest, 0); | |
1825 | if (GET_CODE (dest) == REG) | |
1826 | maybe_set_rd_gen (REGNO (dest), insn); | |
1827 | } | |
1828 | } | |
1829 | ||
1830 | static void | |
1831 | hash_scan_clobber (x, insn) | |
50b2596f | 1832 | rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED; |
7506f491 DE |
1833 | { |
1834 | /* Currently nothing to do. */ | |
1835 | } | |
1836 | ||
1837 | static void | |
1838 | hash_scan_call (x, insn) | |
50b2596f | 1839 | rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED; |
7506f491 DE |
1840 | { |
1841 | /* Currently nothing to do. */ | |
1842 | } | |
1843 | ||
1844 | /* Process INSN and add hash table entries as appropriate. | |
1845 | ||
1846 | Only available expressions that set a single pseudo-reg are recorded. | |
1847 | ||
1848 | Single sets in a PARALLEL could be handled, but it's an extra complication | |
1849 | that isn't dealt with right now. The trick is handling the CLOBBERs that | |
1850 | are also in the PARALLEL. Later. | |
1851 | ||
1852 | If SET_P is non-zero, this is for the assignment hash table, | |
ed79bb3d R |
1853 | otherwise it is for the expression hash table. |
1854 | If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should | |
1855 | not record any expressions. */ | |
7506f491 DE |
1856 | |
1857 | static void | |
ed79bb3d | 1858 | hash_scan_insn (insn, set_p, in_libcall_block) |
7506f491 DE |
1859 | rtx insn; |
1860 | int set_p; | |
48e87cef | 1861 | int in_libcall_block; |
7506f491 DE |
1862 | { |
1863 | rtx pat = PATTERN (insn); | |
1864 | ||
1865 | /* Pick out the sets of INSN and for other forms of instructions record | |
1866 | what's been modified. */ | |
1867 | ||
ed79bb3d | 1868 | if (GET_CODE (pat) == SET && ! in_libcall_block) |
7506f491 DE |
1869 | hash_scan_set (pat, insn, set_p); |
1870 | else if (GET_CODE (pat) == PARALLEL) | |
1871 | { | |
1872 | int i; | |
1873 | ||
1874 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
1875 | { | |
1876 | rtx x = XVECEXP (pat, 0, i); | |
1877 | ||
1878 | if (GET_CODE (x) == SET) | |
1879 | { | |
1880 | if (GET_CODE (SET_SRC (x)) == CALL) | |
1881 | hash_scan_call (SET_SRC (x), insn); | |
1882 | ||
1883 | /* Check if first/last set in this block for classic | |
1884 | gcse, but not for constant/copy propagation. */ | |
1885 | if (optimize_size && !set_p) | |
1886 | { | |
1887 | rtx dest = SET_DEST (x); | |
1888 | ||
1889 | while (GET_CODE (dest) == SUBREG | |
1890 | || GET_CODE (dest) == ZERO_EXTRACT | |
1891 | || GET_CODE (dest) == SIGN_EXTRACT | |
1892 | || GET_CODE (dest) == STRICT_LOW_PART) | |
1893 | dest = XEXP (dest, 0); | |
1894 | if (GET_CODE (dest) == REG) | |
1895 | maybe_set_rd_gen (REGNO (dest), insn); | |
1896 | } | |
1897 | } | |
1898 | else if (GET_CODE (x) == CLOBBER) | |
1899 | hash_scan_clobber (x, insn); | |
1900 | else if (GET_CODE (x) == CALL) | |
1901 | hash_scan_call (x, insn); | |
1902 | } | |
1903 | } | |
1904 | else if (GET_CODE (pat) == CLOBBER) | |
1905 | hash_scan_clobber (pat, insn); | |
1906 | else if (GET_CODE (pat) == CALL) | |
1907 | hash_scan_call (pat, insn); | |
1908 | } | |
1909 | ||
1910 | static void | |
1911 | dump_hash_table (file, name, table, table_size, total_size) | |
1912 | FILE *file; | |
1913 | char *name; | |
1914 | struct expr **table; | |
1915 | int table_size, total_size; | |
1916 | { | |
1917 | int i; | |
1918 | /* Flattened out table, so it's printed in proper order. */ | |
1919 | struct expr **flat_table = (struct expr **) alloca (total_size * sizeof (struct expr *)); | |
1920 | unsigned int *hash_val = (unsigned int *) alloca (total_size * sizeof (unsigned int)); | |
1921 | ||
1922 | bzero ((char *) flat_table, total_size * sizeof (struct expr *)); | |
1923 | for (i = 0; i < table_size; i++) | |
1924 | { | |
1925 | struct expr *expr; | |
1926 | ||
1927 | for (expr = table[i]; expr != NULL; expr = expr->next_same_hash) | |
1928 | { | |
1929 | flat_table[expr->bitmap_index] = expr; | |
1930 | hash_val[expr->bitmap_index] = i; | |
1931 | } | |
1932 | } | |
1933 | ||
1934 | fprintf (file, "%s hash table (%d buckets, %d entries)\n", | |
1935 | name, table_size, total_size); | |
1936 | ||
1937 | for (i = 0; i < total_size; i++) | |
1938 | { | |
1939 | struct expr *expr = flat_table[i]; | |
1940 | ||
1941 | fprintf (file, "Index %d (hash value %d)\n ", | |
1942 | expr->bitmap_index, hash_val[i]); | |
1943 | print_rtl (file, expr->expr); | |
1944 | fprintf (file, "\n"); | |
1945 | } | |
1946 | ||
1947 | fprintf (file, "\n"); | |
1948 | } | |
1949 | ||
1950 | /* Record register first/last/block set information for REGNO in INSN. | |
1951 | reg_first_set records the first place in the block where the register | |
1952 | is set and is used to compute "anticipatability". | |
1953 | reg_last_set records the last place in the block where the register | |
1954 | is set and is used to compute "availability". | |
1955 | reg_set_in_block records whether the register is set in the block | |
1956 | and is used to compute "transparency". */ | |
1957 | ||
1958 | static void | |
1959 | record_last_reg_set_info (insn, regno) | |
1960 | rtx insn; | |
1961 | int regno; | |
1962 | { | |
b86ba9c8 | 1963 | if (reg_first_set[regno] == NEVER_SET) |
7506f491 DE |
1964 | reg_first_set[regno] = INSN_CUID (insn); |
1965 | reg_last_set[regno] = INSN_CUID (insn); | |
1966 | SET_BIT (reg_set_in_block[BLOCK_NUM (insn)], regno); | |
1967 | } | |
1968 | ||
1969 | /* Record memory first/last/block set information for INSN. */ | |
1970 | ||
1971 | static void | |
1972 | record_last_mem_set_info (insn) | |
1973 | rtx insn; | |
1974 | { | |
b86ba9c8 | 1975 | if (mem_first_set == NEVER_SET) |
7506f491 DE |
1976 | mem_first_set = INSN_CUID (insn); |
1977 | mem_last_set = INSN_CUID (insn); | |
1978 | mem_set_in_block[BLOCK_NUM (insn)] = 1; | |
1979 | } | |
1980 | ||
1981 | /* Used for communicating between next two routines. */ | |
1982 | static rtx last_set_insn; | |
1983 | ||
1984 | /* Called from compute_hash_table via note_stores to handle one | |
1985 | SET or CLOBBER in an insn. */ | |
1986 | ||
1987 | static void | |
1988 | record_last_set_info (dest, setter) | |
50b2596f | 1989 | rtx dest, setter ATTRIBUTE_UNUSED; |
7506f491 DE |
1990 | { |
1991 | if (GET_CODE (dest) == SUBREG) | |
1992 | dest = SUBREG_REG (dest); | |
1993 | ||
1994 | if (GET_CODE (dest) == REG) | |
1995 | record_last_reg_set_info (last_set_insn, REGNO (dest)); | |
1996 | else if (GET_CODE (dest) == MEM | |
1997 | /* Ignore pushes, they clobber nothing. */ | |
1998 | && ! push_operand (dest, GET_MODE (dest))) | |
1999 | record_last_mem_set_info (last_set_insn); | |
2000 | } | |
2001 | ||
2002 | /* Top level function to create an expression or assignment hash table. | |
2003 | ||
2004 | Expression entries are placed in the hash table if | |
2005 | - they are of the form (set (pseudo-reg) src), | |
2006 | - src is something we want to perform GCSE on, | |
2007 | - none of the operands are subsequently modified in the block | |
2008 | ||
2009 | Assignment entries are placed in the hash table if | |
2010 | - they are of the form (set (pseudo-reg) src), | |
2011 | - src is something we want to perform const/copy propagation on, | |
2012 | - none of the operands or target are subsequently modified in the block | |
2013 | Currently src must be a pseudo-reg or a const_int. | |
2014 | ||
2015 | F is the first insn. | |
2016 | SET_P is non-zero for computing the assignment hash table. */ | |
2017 | ||
2018 | static void | |
2019 | compute_hash_table (f, set_p) | |
c16ddde3 | 2020 | rtx f ATTRIBUTE_UNUSED; |
7506f491 DE |
2021 | int set_p; |
2022 | { | |
2023 | int bb; | |
2024 | ||
2025 | /* While we compute the hash table we also compute a bit array of which | |
2026 | registers are set in which blocks. | |
2027 | We also compute which blocks set memory, in the absence of aliasing | |
2028 | support [which is TODO]. | |
2029 | ??? This isn't needed during const/copy propagation, but it's cheap to | |
2030 | compute. Later. */ | |
2031 | sbitmap_vector_zero (reg_set_in_block, n_basic_blocks); | |
2032 | bzero ((char *) mem_set_in_block, n_basic_blocks); | |
2033 | ||
2034 | /* Some working arrays used to track first and last set in each block. */ | |
2035 | /* ??? One could use alloca here, but at some size a threshold is crossed | |
2036 | beyond which one should use malloc. Are we at that threshold here? */ | |
2037 | reg_first_set = (int *) gmalloc (max_gcse_regno * sizeof (int)); | |
2038 | reg_last_set = (int *) gmalloc (max_gcse_regno * sizeof (int)); | |
2039 | ||
2040 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2041 | { | |
2042 | rtx insn; | |
2043 | int regno; | |
ed79bb3d | 2044 | int in_libcall_block; |
b86ba9c8 | 2045 | int i; |
7506f491 DE |
2046 | |
2047 | /* First pass over the instructions records information used to | |
2048 | determine when registers and memory are first and last set. | |
2049 | ??? The mem_set_in_block and hard-reg reg_set_in_block computation | |
2050 | could be moved to compute_sets since they currently don't change. */ | |
2051 | ||
b86ba9c8 GK |
2052 | for (i = 0; i < max_gcse_regno; i++) |
2053 | reg_first_set[i] = reg_last_set[i] = NEVER_SET; | |
2054 | mem_first_set = NEVER_SET; | |
2055 | mem_last_set = NEVER_SET; | |
7506f491 | 2056 | |
3b413743 RH |
2057 | for (insn = BLOCK_HEAD (bb); |
2058 | insn && insn != NEXT_INSN (BLOCK_END (bb)); | |
7506f491 DE |
2059 | insn = NEXT_INSN (insn)) |
2060 | { | |
2061 | #ifdef NON_SAVING_SETJMP | |
2062 | if (NON_SAVING_SETJMP && GET_CODE (insn) == NOTE | |
2063 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP) | |
2064 | { | |
2065 | for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) | |
2066 | record_last_reg_set_info (insn, regno); | |
2067 | continue; | |
2068 | } | |
2069 | #endif | |
2070 | ||
2071 | if (GET_RTX_CLASS (GET_CODE (insn)) != 'i') | |
2072 | continue; | |
2073 | ||
2074 | if (GET_CODE (insn) == CALL_INSN) | |
2075 | { | |
2076 | for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) | |
15f8470f JL |
2077 | if ((call_used_regs[regno] |
2078 | && regno != STACK_POINTER_REGNUM | |
2079 | #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2080 | && regno != HARD_FRAME_POINTER_REGNUM | |
2081 | #endif | |
2082 | #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2083 | && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno]) | |
2084 | #endif | |
2085 | #if defined (PIC_OFFSET_TABLE_REGNUM) && !defined (PIC_OFFSET_TABLE_REG_CALL_CLOBBERED) | |
2086 | && ! (regno == PIC_OFFSET_TABLE_REGNUM && flag_pic) | |
2087 | #endif | |
2088 | ||
2089 | && regno != FRAME_POINTER_REGNUM) | |
2090 | || global_regs[regno]) | |
7506f491 DE |
2091 | record_last_reg_set_info (insn, regno); |
2092 | if (! CONST_CALL_P (insn)) | |
2093 | record_last_mem_set_info (insn); | |
2094 | } | |
2095 | ||
2096 | last_set_insn = insn; | |
2097 | note_stores (PATTERN (insn), record_last_set_info); | |
2098 | } | |
2099 | ||
2100 | /* The next pass builds the hash table. */ | |
2101 | ||
3b413743 RH |
2102 | for (insn = BLOCK_HEAD (bb), in_libcall_block = 0; |
2103 | insn && insn != NEXT_INSN (BLOCK_END (bb)); | |
7506f491 DE |
2104 | insn = NEXT_INSN (insn)) |
2105 | { | |
2106 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
ed79bb3d R |
2107 | { |
2108 | if (find_reg_note (insn, REG_LIBCALL, NULL_RTX)) | |
2109 | in_libcall_block = 1; | |
2110 | else if (find_reg_note (insn, REG_RETVAL, NULL_RTX)) | |
2111 | in_libcall_block = 0; | |
2112 | hash_scan_insn (insn, set_p, in_libcall_block); | |
2113 | } | |
7506f491 DE |
2114 | } |
2115 | } | |
2116 | ||
2117 | free (reg_first_set); | |
2118 | free (reg_last_set); | |
2119 | /* Catch bugs early. */ | |
2120 | reg_first_set = reg_last_set = 0; | |
2121 | } | |
2122 | ||
2123 | /* Allocate space for the set hash table. | |
2124 | N_INSNS is the number of instructions in the function. | |
2125 | It is used to determine the number of buckets to use. */ | |
2126 | ||
2127 | static void | |
2128 | alloc_set_hash_table (n_insns) | |
2129 | int n_insns; | |
2130 | { | |
2131 | int n; | |
2132 | ||
2133 | set_hash_table_size = n_insns / 4; | |
2134 | if (set_hash_table_size < 11) | |
2135 | set_hash_table_size = 11; | |
2136 | /* Attempt to maintain efficient use of hash table. | |
2137 | Making it an odd number is simplest for now. | |
2138 | ??? Later take some measurements. */ | |
2139 | set_hash_table_size |= 1; | |
2140 | n = set_hash_table_size * sizeof (struct expr *); | |
2141 | set_hash_table = (struct expr **) gmalloc (n); | |
2142 | } | |
2143 | ||
2144 | /* Free things allocated by alloc_set_hash_table. */ | |
2145 | ||
2146 | static void | |
2147 | free_set_hash_table () | |
2148 | { | |
2149 | free (set_hash_table); | |
2150 | } | |
2151 | ||
2152 | /* Compute the hash table for doing copy/const propagation. */ | |
2153 | ||
2154 | static void | |
2155 | compute_set_hash_table (f) | |
2156 | rtx f; | |
2157 | { | |
2158 | /* Initialize count of number of entries in hash table. */ | |
2159 | n_sets = 0; | |
2160 | bzero ((char *) set_hash_table, set_hash_table_size * sizeof (struct expr *)); | |
2161 | ||
2162 | compute_hash_table (f, 1); | |
2163 | } | |
2164 | ||
2165 | /* Allocate space for the expression hash table. | |
2166 | N_INSNS is the number of instructions in the function. | |
2167 | It is used to determine the number of buckets to use. */ | |
2168 | ||
2169 | static void | |
2170 | alloc_expr_hash_table (n_insns) | |
2171 | int n_insns; | |
2172 | { | |
2173 | int n; | |
2174 | ||
2175 | expr_hash_table_size = n_insns / 2; | |
2176 | /* Make sure the amount is usable. */ | |
2177 | if (expr_hash_table_size < 11) | |
2178 | expr_hash_table_size = 11; | |
2179 | /* Attempt to maintain efficient use of hash table. | |
2180 | Making it an odd number is simplest for now. | |
2181 | ??? Later take some measurements. */ | |
2182 | expr_hash_table_size |= 1; | |
2183 | n = expr_hash_table_size * sizeof (struct expr *); | |
2184 | expr_hash_table = (struct expr **) gmalloc (n); | |
2185 | } | |
2186 | ||
2187 | /* Free things allocated by alloc_expr_hash_table. */ | |
2188 | ||
2189 | static void | |
2190 | free_expr_hash_table () | |
2191 | { | |
2192 | free (expr_hash_table); | |
2193 | } | |
2194 | ||
2195 | /* Compute the hash table for doing GCSE. */ | |
2196 | ||
2197 | static void | |
2198 | compute_expr_hash_table (f) | |
2199 | rtx f; | |
2200 | { | |
2201 | /* Initialize count of number of entries in hash table. */ | |
2202 | n_exprs = 0; | |
2203 | bzero ((char *) expr_hash_table, expr_hash_table_size * sizeof (struct expr *)); | |
2204 | ||
2205 | compute_hash_table (f, 0); | |
2206 | } | |
2207 | \f | |
2208 | /* Expression tracking support. */ | |
2209 | ||
2210 | /* Lookup pattern PAT in the expression table. | |
2211 | The result is a pointer to the table entry, or NULL if not found. */ | |
2212 | ||
2213 | static struct expr * | |
2214 | lookup_expr (pat) | |
2215 | rtx pat; | |
2216 | { | |
2217 | int do_not_record_p; | |
2218 | unsigned int hash = hash_expr (pat, GET_MODE (pat), &do_not_record_p, | |
2219 | expr_hash_table_size); | |
2220 | struct expr *expr; | |
2221 | ||
2222 | if (do_not_record_p) | |
2223 | return NULL; | |
2224 | ||
2225 | expr = expr_hash_table[hash]; | |
2226 | ||
2227 | while (expr && ! expr_equiv_p (expr->expr, pat)) | |
2228 | expr = expr->next_same_hash; | |
2229 | ||
2230 | return expr; | |
2231 | } | |
2232 | ||
2233 | /* Lookup REGNO in the set table. | |
2234 | If PAT is non-NULL look for the entry that matches it, otherwise return | |
2235 | the first entry for REGNO. | |
2236 | The result is a pointer to the table entry, or NULL if not found. */ | |
2237 | ||
2238 | static struct expr * | |
2239 | lookup_set (regno, pat) | |
2240 | int regno; | |
2241 | rtx pat; | |
2242 | { | |
2243 | unsigned int hash = hash_set (regno, set_hash_table_size); | |
2244 | struct expr *expr; | |
2245 | ||
2246 | expr = set_hash_table[hash]; | |
2247 | ||
2248 | if (pat) | |
2249 | { | |
2250 | while (expr && ! expr_equiv_p (expr->expr, pat)) | |
2251 | expr = expr->next_same_hash; | |
2252 | } | |
2253 | else | |
2254 | { | |
2255 | while (expr && REGNO (SET_DEST (expr->expr)) != regno) | |
2256 | expr = expr->next_same_hash; | |
2257 | } | |
2258 | ||
2259 | return expr; | |
2260 | } | |
2261 | ||
2262 | /* Return the next entry for REGNO in list EXPR. */ | |
2263 | ||
2264 | static struct expr * | |
2265 | next_set (regno, expr) | |
2266 | int regno; | |
2267 | struct expr *expr; | |
2268 | { | |
2269 | do | |
2270 | expr = expr->next_same_hash; | |
2271 | while (expr && REGNO (SET_DEST (expr->expr)) != regno); | |
2272 | return expr; | |
2273 | } | |
2274 | ||
2275 | /* Reset tables used to keep track of what's still available [since the | |
2276 | start of the block]. */ | |
2277 | ||
2278 | static void | |
2279 | reset_opr_set_tables () | |
2280 | { | |
2281 | /* Maintain a bitmap of which regs have been set since beginning of | |
2282 | the block. */ | |
2283 | sbitmap_zero (reg_set_bitmap); | |
2284 | /* Also keep a record of the last instruction to modify memory. | |
2285 | For now this is very trivial, we only record whether any memory | |
2286 | location has been modified. */ | |
2287 | mem_last_set = 0; | |
2288 | } | |
2289 | ||
2290 | /* Return non-zero if the operands of X are not set before INSN in | |
2291 | INSN's basic block. */ | |
2292 | ||
2293 | static int | |
2294 | oprs_not_set_p (x, insn) | |
2295 | rtx x, insn; | |
2296 | { | |
2297 | int i; | |
2298 | enum rtx_code code; | |
2299 | char *fmt; | |
2300 | ||
2301 | /* repeat is used to turn tail-recursion into iteration. */ | |
2302 | repeat: | |
2303 | ||
2304 | if (x == 0) | |
2305 | return 1; | |
2306 | ||
2307 | code = GET_CODE (x); | |
2308 | switch (code) | |
2309 | { | |
2310 | case PC: | |
2311 | case CC0: | |
2312 | case CONST: | |
2313 | case CONST_INT: | |
2314 | case CONST_DOUBLE: | |
2315 | case SYMBOL_REF: | |
2316 | case LABEL_REF: | |
2317 | case ADDR_VEC: | |
2318 | case ADDR_DIFF_VEC: | |
2319 | return 1; | |
2320 | ||
2321 | case MEM: | |
2322 | if (mem_last_set != 0) | |
2323 | return 0; | |
2324 | x = XEXP (x, 0); | |
2325 | goto repeat; | |
2326 | ||
2327 | case REG: | |
2328 | return ! TEST_BIT (reg_set_bitmap, REGNO (x)); | |
2329 | ||
2330 | default: | |
2331 | break; | |
2332 | } | |
2333 | ||
2334 | fmt = GET_RTX_FORMAT (code); | |
2335 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2336 | { | |
2337 | if (fmt[i] == 'e') | |
2338 | { | |
2339 | int not_set_p; | |
2340 | /* If we are about to do the last recursive call | |
2341 | needed at this level, change it into iteration. | |
2342 | This function is called enough to be worth it. */ | |
2343 | if (i == 0) | |
2344 | { | |
2345 | x = XEXP (x, 0); | |
2346 | goto repeat; | |
2347 | } | |
2348 | not_set_p = oprs_not_set_p (XEXP (x, i), insn); | |
2349 | if (! not_set_p) | |
2350 | return 0; | |
2351 | } | |
2352 | else if (fmt[i] == 'E') | |
2353 | { | |
2354 | int j; | |
2355 | for (j = 0; j < XVECLEN (x, i); j++) | |
2356 | { | |
2357 | int not_set_p = oprs_not_set_p (XVECEXP (x, i, j), insn); | |
2358 | if (! not_set_p) | |
2359 | return 0; | |
2360 | } | |
2361 | } | |
2362 | } | |
2363 | ||
2364 | return 1; | |
2365 | } | |
2366 | ||
2367 | /* Mark things set by a CALL. */ | |
2368 | ||
2369 | static void | |
2370 | mark_call (pat, insn) | |
50b2596f | 2371 | rtx pat ATTRIBUTE_UNUSED, insn; |
7506f491 DE |
2372 | { |
2373 | mem_last_set = INSN_CUID (insn); | |
2374 | } | |
2375 | ||
2376 | /* Mark things set by a SET. */ | |
2377 | ||
2378 | static void | |
2379 | mark_set (pat, insn) | |
2380 | rtx pat, insn; | |
2381 | { | |
2382 | rtx dest = SET_DEST (pat); | |
2383 | ||
2384 | while (GET_CODE (dest) == SUBREG | |
2385 | || GET_CODE (dest) == ZERO_EXTRACT | |
2386 | || GET_CODE (dest) == SIGN_EXTRACT | |
2387 | || GET_CODE (dest) == STRICT_LOW_PART) | |
2388 | dest = XEXP (dest, 0); | |
2389 | ||
2390 | if (GET_CODE (dest) == REG) | |
2391 | SET_BIT (reg_set_bitmap, REGNO (dest)); | |
2392 | else if (GET_CODE (dest) == MEM) | |
2393 | mem_last_set = INSN_CUID (insn); | |
2394 | ||
2395 | if (GET_CODE (SET_SRC (pat)) == CALL) | |
2396 | mark_call (SET_SRC (pat), insn); | |
2397 | } | |
2398 | ||
2399 | /* Record things set by a CLOBBER. */ | |
2400 | ||
2401 | static void | |
2402 | mark_clobber (pat, insn) | |
2403 | rtx pat, insn; | |
2404 | { | |
2405 | rtx clob = XEXP (pat, 0); | |
2406 | ||
2407 | while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART) | |
2408 | clob = XEXP (clob, 0); | |
2409 | ||
2410 | if (GET_CODE (clob) == REG) | |
2411 | SET_BIT (reg_set_bitmap, REGNO (clob)); | |
2412 | else | |
2413 | mem_last_set = INSN_CUID (insn); | |
2414 | } | |
2415 | ||
2416 | /* Record things set by INSN. | |
2417 | This data is used by oprs_not_set_p. */ | |
2418 | ||
2419 | static void | |
2420 | mark_oprs_set (insn) | |
2421 | rtx insn; | |
2422 | { | |
2423 | rtx pat = PATTERN (insn); | |
2424 | ||
2425 | if (GET_CODE (pat) == SET) | |
2426 | mark_set (pat, insn); | |
2427 | else if (GET_CODE (pat) == PARALLEL) | |
2428 | { | |
2429 | int i; | |
2430 | ||
2431 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
2432 | { | |
2433 | rtx x = XVECEXP (pat, 0, i); | |
2434 | ||
2435 | if (GET_CODE (x) == SET) | |
2436 | mark_set (x, insn); | |
2437 | else if (GET_CODE (x) == CLOBBER) | |
2438 | mark_clobber (x, insn); | |
2439 | else if (GET_CODE (x) == CALL) | |
2440 | mark_call (x, insn); | |
2441 | } | |
2442 | } | |
2443 | else if (GET_CODE (pat) == CLOBBER) | |
2444 | mark_clobber (pat, insn); | |
2445 | else if (GET_CODE (pat) == CALL) | |
2446 | mark_call (pat, insn); | |
2447 | } | |
2448 | \f | |
2449 | /* Classic GCSE reaching definition support. */ | |
2450 | ||
2451 | /* Allocate reaching def variables. */ | |
2452 | ||
2453 | static void | |
2454 | alloc_rd_mem (n_blocks, n_insns) | |
2455 | int n_blocks, n_insns; | |
2456 | { | |
2457 | rd_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2458 | sbitmap_vector_zero (rd_kill, n_basic_blocks); | |
2459 | ||
2460 | rd_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2461 | sbitmap_vector_zero (rd_gen, n_basic_blocks); | |
2462 | ||
2463 | reaching_defs = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2464 | sbitmap_vector_zero (reaching_defs, n_basic_blocks); | |
2465 | ||
2466 | rd_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns); | |
2467 | sbitmap_vector_zero (rd_out, n_basic_blocks); | |
2468 | } | |
2469 | ||
2470 | /* Free reaching def variables. */ | |
2471 | ||
2472 | static void | |
2473 | free_rd_mem () | |
2474 | { | |
2475 | free (rd_kill); | |
2476 | free (rd_gen); | |
2477 | free (reaching_defs); | |
2478 | free (rd_out); | |
2479 | } | |
2480 | ||
2481 | /* Add INSN to the kills of BB. | |
2482 | REGNO, set in BB, is killed by INSN. */ | |
2483 | ||
2484 | static void | |
2485 | handle_rd_kill_set (insn, regno, bb) | |
2486 | rtx insn; | |
2487 | int regno, bb; | |
2488 | { | |
2489 | struct reg_set *this_reg = reg_set_table[regno]; | |
2490 | ||
2491 | while (this_reg) | |
2492 | { | |
2493 | if (BLOCK_NUM (this_reg->insn) != BLOCK_NUM (insn)) | |
2494 | SET_BIT (rd_kill[bb], INSN_CUID (this_reg->insn)); | |
2495 | this_reg = this_reg->next; | |
2496 | } | |
2497 | } | |
2498 | ||
50b2596f | 2499 | void |
7506f491 DE |
2500 | dump_rd_table (file, title, bmap) |
2501 | FILE *file; | |
2502 | char *title; | |
2503 | sbitmap *bmap; | |
2504 | { | |
2505 | int bb,cuid,i,j,n; | |
2506 | ||
2507 | fprintf (file, "%s\n", title); | |
2508 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2509 | { | |
2510 | fprintf (file, "BB %d\n", bb); | |
2511 | dump_sbitmap (file, bmap[bb]); | |
2512 | for (i = n = cuid = 0; i < bmap[bb]->size; i++) | |
2513 | { | |
2514 | for (j = 0; j < SBITMAP_ELT_BITS; j++, cuid++) | |
2515 | { | |
2516 | if ((bmap[bb]->elms[i] & (1 << j)) != 0) | |
2517 | { | |
2518 | if (n % 10 == 0) | |
2519 | fprintf (file, " "); | |
2520 | fprintf (file, " %d", INSN_UID (CUID_INSN (cuid))); | |
2521 | n++; | |
2522 | } | |
2523 | } | |
2524 | } | |
2525 | if (n != 0) | |
2526 | fprintf (file, "\n"); | |
2527 | } | |
2528 | fprintf (file, "\n"); | |
2529 | } | |
2530 | ||
2531 | /* Compute the set of kill's for reaching definitions. */ | |
2532 | ||
2533 | static void | |
2534 | compute_kill_rd () | |
2535 | { | |
2536 | int bb,cuid; | |
2537 | ||
2538 | /* For each block | |
2539 | For each set bit in `gen' of the block (i.e each insn which | |
2540 | generates a definition in the block) | |
2541 | Call the reg set by the insn corresponding to that bit regx | |
2542 | Look at the linked list starting at reg_set_table[regx] | |
2543 | For each setting of regx in the linked list, which is not in | |
2544 | this block | |
2545 | Set the bit in `kill' corresponding to that insn | |
2546 | */ | |
2547 | ||
2548 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2549 | { | |
2550 | for (cuid = 0; cuid < max_cuid; cuid++) | |
2551 | { | |
2552 | if (TEST_BIT (rd_gen[bb], cuid)) | |
2553 | { | |
2554 | rtx insn = CUID_INSN (cuid); | |
2555 | rtx pat = PATTERN (insn); | |
2556 | ||
2557 | if (GET_CODE (insn) == CALL_INSN) | |
2558 | { | |
2559 | int regno; | |
2560 | ||
2561 | for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) | |
2562 | { | |
15f8470f JL |
2563 | if ((call_used_regs[regno] |
2564 | && regno != STACK_POINTER_REGNUM | |
2565 | #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2566 | && regno != HARD_FRAME_POINTER_REGNUM | |
2567 | #endif | |
2568 | #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2569 | && ! (regno == ARG_POINTER_REGNUM | |
2570 | && fixed_regs[regno]) | |
2571 | #endif | |
2572 | #if defined (PIC_OFFSET_TABLE_REGNUM) && !defined (PIC_OFFSET_TABLE_REG_CALL_CLOBBERED) | |
2573 | && ! (regno == PIC_OFFSET_TABLE_REGNUM && flag_pic) | |
2574 | #endif | |
2575 | && regno != FRAME_POINTER_REGNUM) | |
2576 | || global_regs[regno]) | |
7506f491 DE |
2577 | handle_rd_kill_set (insn, regno, bb); |
2578 | } | |
2579 | } | |
2580 | ||
2581 | if (GET_CODE (pat) == PARALLEL) | |
2582 | { | |
2583 | int i; | |
2584 | ||
2585 | /* We work backwards because ... */ | |
2586 | for (i = XVECLEN (pat, 0) - 1; i >= 0; i--) | |
2587 | { | |
2588 | enum rtx_code code = GET_CODE (XVECEXP (pat, 0, i)); | |
2589 | if ((code == SET || code == CLOBBER) | |
2590 | && GET_CODE (XEXP (XVECEXP (pat, 0, i), 0)) == REG) | |
2591 | handle_rd_kill_set (insn, | |
2592 | REGNO (XEXP (XVECEXP (pat, 0, i), 0)), | |
2593 | bb); | |
2594 | } | |
2595 | } | |
2596 | else if (GET_CODE (pat) == SET) | |
2597 | { | |
2598 | if (GET_CODE (SET_DEST (pat)) == REG) | |
2599 | { | |
2600 | /* Each setting of this register outside of this block | |
2601 | must be marked in the set of kills in this block. */ | |
2602 | handle_rd_kill_set (insn, REGNO (SET_DEST (pat)), bb); | |
2603 | } | |
2604 | } | |
2605 | /* FIXME: CLOBBER? */ | |
2606 | } | |
2607 | } | |
2608 | } | |
2609 | } | |
2610 | ||
2611 | /* Compute the reaching definitions as in | |
2612 | Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman, | |
2613 | Chapter 10. It is the same algorithm as used for computing available | |
2614 | expressions but applied to the gens and kills of reaching definitions. */ | |
2615 | ||
2616 | static void | |
2617 | compute_rd () | |
2618 | { | |
2619 | int bb, changed, passes; | |
2620 | ||
2621 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2622 | sbitmap_copy (rd_out[bb] /*dst*/, rd_gen[bb] /*src*/); | |
2623 | ||
2624 | passes = 0; | |
2625 | changed = 1; | |
2626 | while (changed) | |
2627 | { | |
2628 | changed = 0; | |
2629 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2630 | { | |
2631 | sbitmap_union_of_predecessors (reaching_defs[bb], rd_out, | |
2632 | bb, s_preds); | |
2633 | changed |= sbitmap_union_of_diff (rd_out[bb], rd_gen[bb], | |
2634 | reaching_defs[bb], rd_kill[bb]); | |
2635 | } | |
2636 | passes++; | |
2637 | } | |
2638 | ||
2639 | if (gcse_file) | |
2640 | fprintf (gcse_file, "reaching def computation: %d passes\n", passes); | |
2641 | } | |
2642 | \f | |
2643 | /* Classic GCSE available expression support. */ | |
2644 | ||
2645 | /* Allocate memory for available expression computation. */ | |
2646 | ||
2647 | static void | |
2648 | alloc_avail_expr_mem (n_blocks, n_exprs) | |
2649 | int n_blocks, n_exprs; | |
2650 | { | |
2651 | ae_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
2652 | sbitmap_vector_zero (ae_kill, n_basic_blocks); | |
2653 | ||
2654 | ae_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
2655 | sbitmap_vector_zero (ae_gen, n_basic_blocks); | |
2656 | ||
2657 | ae_in = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
2658 | sbitmap_vector_zero (ae_in, n_basic_blocks); | |
2659 | ||
2660 | ae_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs); | |
2661 | sbitmap_vector_zero (ae_out, n_basic_blocks); | |
2662 | ||
2663 | u_bitmap = (sbitmap) sbitmap_alloc (n_exprs); | |
2664 | sbitmap_ones (u_bitmap); | |
2665 | } | |
2666 | ||
2667 | static void | |
2668 | free_avail_expr_mem () | |
2669 | { | |
2670 | free (ae_kill); | |
2671 | free (ae_gen); | |
2672 | free (ae_in); | |
2673 | free (ae_out); | |
2674 | free (u_bitmap); | |
2675 | } | |
2676 | ||
2677 | /* Compute the set of available expressions generated in each basic block. */ | |
2678 | ||
2679 | static void | |
2680 | compute_ae_gen () | |
2681 | { | |
2682 | int i; | |
2683 | ||
2684 | /* For each recorded occurrence of each expression, set ae_gen[bb][expr]. | |
2685 | This is all we have to do because an expression is not recorded if it | |
2686 | is not available, and the only expressions we want to work with are the | |
2687 | ones that are recorded. */ | |
2688 | ||
2689 | for (i = 0; i < expr_hash_table_size; i++) | |
2690 | { | |
2691 | struct expr *expr = expr_hash_table[i]; | |
2692 | while (expr != NULL) | |
2693 | { | |
2694 | struct occr *occr = expr->avail_occr; | |
2695 | while (occr != NULL) | |
2696 | { | |
2697 | SET_BIT (ae_gen[BLOCK_NUM (occr->insn)], expr->bitmap_index); | |
2698 | occr = occr->next; | |
2699 | } | |
2700 | expr = expr->next_same_hash; | |
2701 | } | |
2702 | } | |
2703 | } | |
2704 | ||
2705 | /* Return non-zero if expression X is killed in BB. */ | |
2706 | ||
2707 | static int | |
2708 | expr_killed_p (x, bb) | |
2709 | rtx x; | |
2710 | int bb; | |
2711 | { | |
2712 | int i; | |
2713 | enum rtx_code code; | |
2714 | char *fmt; | |
2715 | ||
2716 | /* repeat is used to turn tail-recursion into iteration. */ | |
2717 | repeat: | |
2718 | ||
2719 | if (x == 0) | |
2720 | return 1; | |
2721 | ||
2722 | code = GET_CODE (x); | |
2723 | switch (code) | |
2724 | { | |
2725 | case REG: | |
2726 | return TEST_BIT (reg_set_in_block[bb], REGNO (x)); | |
2727 | ||
2728 | case MEM: | |
2729 | if (mem_set_in_block[bb]) | |
2730 | return 1; | |
2731 | x = XEXP (x, 0); | |
2732 | goto repeat; | |
2733 | ||
2734 | case PC: | |
2735 | case CC0: /*FIXME*/ | |
2736 | case CONST: | |
2737 | case CONST_INT: | |
2738 | case CONST_DOUBLE: | |
2739 | case SYMBOL_REF: | |
2740 | case LABEL_REF: | |
2741 | case ADDR_VEC: | |
2742 | case ADDR_DIFF_VEC: | |
2743 | return 0; | |
2744 | ||
2745 | default: | |
2746 | break; | |
2747 | } | |
2748 | ||
2749 | i = GET_RTX_LENGTH (code) - 1; | |
2750 | fmt = GET_RTX_FORMAT (code); | |
2751 | for (; i >= 0; i--) | |
2752 | { | |
2753 | if (fmt[i] == 'e') | |
2754 | { | |
2755 | rtx tem = XEXP (x, i); | |
2756 | ||
2757 | /* If we are about to do the last recursive call | |
2758 | needed at this level, change it into iteration. | |
2759 | This function is called enough to be worth it. */ | |
2760 | if (i == 0) | |
2761 | { | |
2762 | x = tem; | |
2763 | goto repeat; | |
2764 | } | |
2765 | if (expr_killed_p (tem, bb)) | |
2766 | return 1; | |
2767 | } | |
2768 | else if (fmt[i] == 'E') | |
2769 | { | |
2770 | int j; | |
2771 | for (j = 0; j < XVECLEN (x, i); j++) | |
2772 | { | |
2773 | if (expr_killed_p (XVECEXP (x, i, j), bb)) | |
2774 | return 1; | |
2775 | } | |
2776 | } | |
2777 | } | |
2778 | ||
2779 | return 0; | |
2780 | } | |
2781 | ||
2782 | /* Compute the set of available expressions killed in each basic block. */ | |
2783 | ||
2784 | static void | |
2785 | compute_ae_kill () | |
2786 | { | |
2787 | int bb,i; | |
2788 | ||
2789 | for (bb = 0; bb < n_basic_blocks; bb++) | |
2790 | { | |
2791 | for (i = 0; i < expr_hash_table_size; i++) | |
2792 | { | |
2793 | struct expr *expr = expr_hash_table[i]; | |
2794 | ||
2795 | for ( ; expr != NULL; expr = expr->next_same_hash) | |
2796 | { | |
2797 | /* Skip EXPR if generated in this block. */ | |
2798 | if (TEST_BIT (ae_gen[bb], expr->bitmap_index)) | |
2799 | continue; | |
2800 | ||
2801 | if (expr_killed_p (expr->expr, bb)) | |
2802 | SET_BIT (ae_kill[bb], expr->bitmap_index); | |
2803 | } | |
2804 | } | |
2805 | } | |
2806 | } | |
2807 | ||
2808 | /* Compute available expressions. | |
2809 | ||
2810 | Implement the algorithm to find available expressions | |
2811 | as given in the Aho Sethi Ullman book, pages 627-631. */ | |
2812 | ||
2813 | static void | |
2814 | compute_available () | |
2815 | { | |
2816 | int bb, changed, passes; | |
2817 | ||
2818 | sbitmap_zero (ae_in[0]); | |
2819 | ||
2820 | sbitmap_copy (ae_out[0] /*dst*/, ae_gen[0] /*src*/); | |
2821 | ||
2822 | for (bb = 1; bb < n_basic_blocks; bb++) | |
2823 | sbitmap_difference (ae_out[bb], u_bitmap, ae_kill[bb]); | |
2824 | ||
2825 | passes = 0; | |
2826 | changed = 1; | |
2827 | while (changed) | |
2828 | { | |
2829 | changed = 0; | |
2830 | for (bb = 1; bb < n_basic_blocks; bb++) | |
2831 | { | |
2832 | sbitmap_intersect_of_predecessors (ae_in[bb], ae_out, | |
2833 | bb, s_preds); | |
2834 | changed |= sbitmap_union_of_diff (ae_out[bb], ae_gen[bb], | |
2835 | ae_in[bb], ae_kill[bb]); | |
2836 | } | |
2837 | passes++; | |
2838 | } | |
2839 | ||
2840 | if (gcse_file) | |
2841 | fprintf (gcse_file, "avail expr computation: %d passes\n", passes); | |
2842 | } | |
2843 | \f | |
2844 | /* Actually perform the Classic GCSE optimizations. */ | |
2845 | ||
2846 | /* Return non-zero if occurrence OCCR of expression EXPR reaches block BB. | |
2847 | ||
2848 | CHECK_SELF_LOOP is non-zero if we should consider a block reaching itself | |
2849 | as a positive reach. We want to do this when there are two computations | |
2850 | of the expression in the block. | |
2851 | ||
2852 | VISITED is a pointer to a working buffer for tracking which BB's have | |
2853 | been visited. It is NULL for the top-level call. | |
2854 | ||
2855 | We treat reaching expressions that go through blocks containing the same | |
2856 | reaching expression as "not reaching". E.g. if EXPR is generated in blocks | |
2857 | 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block | |
2858 | 2 as not reaching. The intent is to improve the probability of finding | |
2859 | only one reaching expression and to reduce register lifetimes by picking | |
2860 | the closest such expression. */ | |
2861 | ||
2862 | static int | |
2863 | expr_reaches_here_p (occr, expr, bb, check_self_loop, visited) | |
2864 | struct occr *occr; | |
2865 | struct expr *expr; | |
2866 | int bb; | |
2867 | int check_self_loop; | |
2868 | char *visited; | |
2869 | { | |
2870 | int_list_ptr pred; | |
2871 | ||
2872 | if (visited == NULL) | |
2873 | { | |
2874 | visited = (char *) alloca (n_basic_blocks); | |
2875 | bzero (visited, n_basic_blocks); | |
2876 | } | |
2877 | ||
2878 | for (pred = s_preds[bb]; pred != NULL; pred = pred->next) | |
2879 | { | |
2880 | int pred_bb = INT_LIST_VAL (pred); | |
2881 | ||
2882 | if (visited[pred_bb]) | |
2883 | { | |
2884 | /* This predecessor has already been visited. | |
2885 | Nothing to do. */ | |
2886 | ; | |
2887 | } | |
2888 | else if (pred_bb == bb) | |
2889 | { | |
2890 | /* BB loops on itself. */ | |
2891 | if (check_self_loop | |
2892 | && TEST_BIT (ae_gen[pred_bb], expr->bitmap_index) | |
2893 | && BLOCK_NUM (occr->insn) == pred_bb) | |
2894 | return 1; | |
2895 | visited[pred_bb] = 1; | |
2896 | } | |
2897 | /* Ignore this predecessor if it kills the expression. */ | |
2898 | else if (TEST_BIT (ae_kill[pred_bb], expr->bitmap_index)) | |
2899 | visited[pred_bb] = 1; | |
2900 | /* Does this predecessor generate this expression? */ | |
2901 | else if (TEST_BIT (ae_gen[pred_bb], expr->bitmap_index)) | |
2902 | { | |
2903 | /* Is this the occurrence we're looking for? | |
2904 | Note that there's only one generating occurrence per block | |
2905 | so we just need to check the block number. */ | |
2906 | if (BLOCK_NUM (occr->insn) == pred_bb) | |
2907 | return 1; | |
2908 | visited[pred_bb] = 1; | |
2909 | } | |
2910 | /* Neither gen nor kill. */ | |
2911 | else | |
2912 | { | |
2913 | visited[pred_bb] = 1; | |
2914 | if (expr_reaches_here_p (occr, expr, pred_bb, check_self_loop, visited)) | |
2915 | return 1; | |
2916 | } | |
2917 | } | |
2918 | ||
2919 | /* All paths have been checked. */ | |
2920 | return 0; | |
2921 | } | |
2922 | ||
2923 | /* Return the instruction that computes EXPR that reaches INSN's basic block. | |
2924 | If there is more than one such instruction, return NULL. | |
2925 | ||
2926 | Called only by handle_avail_expr. */ | |
2927 | ||
2928 | static rtx | |
2929 | computing_insn (expr, insn) | |
2930 | struct expr *expr; | |
2931 | rtx insn; | |
2932 | { | |
2933 | int bb = BLOCK_NUM (insn); | |
2934 | ||
2935 | if (expr->avail_occr->next == NULL) | |
2936 | { | |
2937 | if (BLOCK_NUM (expr->avail_occr->insn) == bb) | |
2938 | { | |
2939 | /* The available expression is actually itself | |
2940 | (i.e. a loop in the flow graph) so do nothing. */ | |
2941 | return NULL; | |
2942 | } | |
2943 | /* (FIXME) Case that we found a pattern that was created by | |
2944 | a substitution that took place. */ | |
2945 | return expr->avail_occr->insn; | |
2946 | } | |
2947 | else | |
2948 | { | |
2949 | /* Pattern is computed more than once. | |
2950 | Search backwards from this insn to see how many of these | |
2951 | computations actually reach this insn. */ | |
2952 | struct occr *occr; | |
2953 | rtx insn_computes_expr = NULL; | |
2954 | int can_reach = 0; | |
2955 | ||
2956 | for (occr = expr->avail_occr; occr != NULL; occr = occr->next) | |
2957 | { | |
2958 | if (BLOCK_NUM (occr->insn) == bb) | |
2959 | { | |
2960 | /* The expression is generated in this block. | |
2961 | The only time we care about this is when the expression | |
2962 | is generated later in the block [and thus there's a loop]. | |
2963 | We let the normal cse pass handle the other cases. */ | |
2964 | if (INSN_CUID (insn) < INSN_CUID (occr->insn)) | |
2965 | { | |
2966 | if (expr_reaches_here_p (occr, expr, bb, 1, NULL)) | |
2967 | { | |
2968 | can_reach++; | |
2969 | if (can_reach > 1) | |
2970 | return NULL; | |
2971 | insn_computes_expr = occr->insn; | |
2972 | } | |
2973 | } | |
2974 | } | |
2975 | else /* Computation of the pattern outside this block. */ | |
2976 | { | |
2977 | if (expr_reaches_here_p (occr, expr, bb, 0, NULL)) | |
2978 | { | |
2979 | can_reach++; | |
2980 | if (can_reach > 1) | |
2981 | return NULL; | |
2982 | insn_computes_expr = occr->insn; | |
2983 | } | |
2984 | } | |
2985 | } | |
2986 | ||
2987 | if (insn_computes_expr == NULL) | |
2988 | abort (); | |
2989 | return insn_computes_expr; | |
2990 | } | |
2991 | } | |
2992 | ||
2993 | /* Return non-zero if the definition in DEF_INSN can reach INSN. | |
2994 | Only called by can_disregard_other_sets. */ | |
2995 | ||
2996 | static int | |
2997 | def_reaches_here_p (insn, def_insn) | |
2998 | rtx insn, def_insn; | |
2999 | { | |
3000 | rtx reg; | |
3001 | ||
3002 | if (TEST_BIT (reaching_defs[BLOCK_NUM (insn)], INSN_CUID (def_insn))) | |
3003 | return 1; | |
3004 | ||
3005 | if (BLOCK_NUM (insn) == BLOCK_NUM (def_insn)) | |
3006 | { | |
3007 | if (INSN_CUID (def_insn) < INSN_CUID (insn)) | |
3008 | { | |
3009 | if (GET_CODE (PATTERN (def_insn)) == PARALLEL) | |
3010 | return 1; | |
3011 | if (GET_CODE (PATTERN (def_insn)) == CLOBBER) | |
3012 | reg = XEXP (PATTERN (def_insn), 0); | |
3013 | else if (GET_CODE (PATTERN (def_insn)) == SET) | |
3014 | reg = SET_DEST (PATTERN (def_insn)); | |
3015 | else | |
3016 | abort (); | |
3017 | return ! reg_set_between_p (reg, NEXT_INSN (def_insn), insn); | |
3018 | } | |
3019 | else | |
3020 | return 0; | |
3021 | } | |
3022 | ||
3023 | return 0; | |
3024 | } | |
3025 | ||
3026 | /* Return non-zero if *ADDR_THIS_REG can only have one value at INSN. | |
3027 | The value returned is the number of definitions that reach INSN. | |
3028 | Returning a value of zero means that [maybe] more than one definition | |
3029 | reaches INSN and the caller can't perform whatever optimization it is | |
3030 | trying. i.e. it is always safe to return zero. */ | |
3031 | ||
3032 | static int | |
3033 | can_disregard_other_sets (addr_this_reg, insn, for_combine) | |
3034 | struct reg_set **addr_this_reg; | |
3035 | rtx insn; | |
3036 | int for_combine; | |
3037 | { | |
3038 | int number_of_reaching_defs = 0; | |
3039 | struct reg_set *this_reg = *addr_this_reg; | |
3040 | ||
3041 | while (this_reg) | |
3042 | { | |
3043 | if (def_reaches_here_p (insn, this_reg->insn)) | |
3044 | { | |
3045 | number_of_reaching_defs++; | |
3046 | /* Ignore parallels for now. */ | |
3047 | if (GET_CODE (PATTERN (this_reg->insn)) == PARALLEL) | |
3048 | return 0; | |
3049 | if (!for_combine | |
3050 | && (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER | |
3051 | || ! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)), | |
3052 | SET_SRC (PATTERN (insn))))) | |
3053 | { | |
3054 | /* A setting of the reg to a different value reaches INSN. */ | |
3055 | return 0; | |
3056 | } | |
3057 | if (number_of_reaching_defs > 1) | |
3058 | { | |
3059 | /* If in this setting the value the register is being | |
3060 | set to is equal to the previous value the register | |
3061 | was set to and this setting reaches the insn we are | |
3062 | trying to do the substitution on then we are ok. */ | |
3063 | ||
3064 | if (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER) | |
3065 | return 0; | |
3066 | if (! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)), | |
3067 | SET_SRC (PATTERN (insn)))) | |
3068 | return 0; | |
3069 | } | |
3070 | *addr_this_reg = this_reg; | |
3071 | } | |
3072 | ||
3073 | /* prev_this_reg = this_reg; */ | |
3074 | this_reg = this_reg->next; | |
3075 | } | |
3076 | ||
3077 | return number_of_reaching_defs; | |
3078 | } | |
3079 | ||
3080 | /* Expression computed by insn is available and the substitution is legal, | |
3081 | so try to perform the substitution. | |
3082 | ||
3083 | The result is non-zero if any changes were made. */ | |
3084 | ||
3085 | static int | |
3086 | handle_avail_expr (insn, expr) | |
3087 | rtx insn; | |
3088 | struct expr *expr; | |
3089 | { | |
3090 | rtx pat, insn_computes_expr; | |
3091 | rtx to; | |
3092 | struct reg_set *this_reg; | |
3093 | int found_setting, use_src; | |
3094 | int changed = 0; | |
3095 | ||
3096 | /* We only handle the case where one computation of the expression | |
3097 | reaches this instruction. */ | |
3098 | insn_computes_expr = computing_insn (expr, insn); | |
3099 | if (insn_computes_expr == NULL) | |
3100 | return 0; | |
3101 | ||
3102 | found_setting = 0; | |
3103 | use_src = 0; | |
3104 | ||
3105 | /* At this point we know only one computation of EXPR outside of this | |
3106 | block reaches this insn. Now try to find a register that the | |
3107 | expression is computed into. */ | |
3108 | ||
3109 | if (GET_CODE (SET_SRC (PATTERN (insn_computes_expr))) == REG) | |
3110 | { | |
3111 | /* This is the case when the available expression that reaches | |
3112 | here has already been handled as an available expression. */ | |
3113 | int regnum_for_replacing = REGNO (SET_SRC (PATTERN (insn_computes_expr))); | |
3114 | /* If the register was created by GCSE we can't use `reg_set_table', | |
3115 | however we know it's set only once. */ | |
3116 | if (regnum_for_replacing >= max_gcse_regno | |
3117 | /* If the register the expression is computed into is set only once, | |
3118 | or only one set reaches this insn, we can use it. */ | |
3119 | || (((this_reg = reg_set_table[regnum_for_replacing]), | |
3120 | this_reg->next == NULL) | |
3121 | || can_disregard_other_sets (&this_reg, insn, 0))) | |
3122 | { | |
3123 | use_src = 1; | |
3124 | found_setting = 1; | |
3125 | } | |
3126 | } | |
3127 | ||
3128 | if (!found_setting) | |
3129 | { | |
3130 | int regnum_for_replacing = REGNO (SET_DEST (PATTERN (insn_computes_expr))); | |
3131 | /* This shouldn't happen. */ | |
3132 | if (regnum_for_replacing >= max_gcse_regno) | |
3133 | abort (); | |
3134 | this_reg = reg_set_table[regnum_for_replacing]; | |
3135 | /* If the register the expression is computed into is set only once, | |
3136 | or only one set reaches this insn, use it. */ | |
3137 | if (this_reg->next == NULL | |
3138 | || can_disregard_other_sets (&this_reg, insn, 0)) | |
3139 | found_setting = 1; | |
3140 | } | |
3141 | ||
3142 | if (found_setting) | |
3143 | { | |
3144 | pat = PATTERN (insn); | |
3145 | if (use_src) | |
3146 | to = SET_SRC (PATTERN (insn_computes_expr)); | |
3147 | else | |
3148 | to = SET_DEST (PATTERN (insn_computes_expr)); | |
3149 | changed = validate_change (insn, &SET_SRC (pat), to, 0); | |
3150 | ||
3151 | /* We should be able to ignore the return code from validate_change but | |
3152 | to play it safe we check. */ | |
3153 | if (changed) | |
3154 | { | |
3155 | gcse_subst_count++; | |
3156 | if (gcse_file != NULL) | |
3157 | { | |
3158 | fprintf (gcse_file, "GCSE: Replacing the source in insn %d with reg %d %s insn %d\n", | |
3159 | INSN_UID (insn), REGNO (to), | |
3160 | use_src ? "from" : "set in", | |
3161 | INSN_UID (insn_computes_expr)); | |
3162 | } | |
3163 | ||
3164 | } | |
3165 | } | |
3166 | /* The register that the expr is computed into is set more than once. */ | |
3167 | else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/) | |
3168 | { | |
3169 | /* Insert an insn after insnx that copies the reg set in insnx | |
3170 | into a new pseudo register call this new register REGN. | |
3171 | From insnb until end of basic block or until REGB is set | |
3172 | replace all uses of REGB with REGN. */ | |
3173 | rtx new_insn; | |
3174 | ||
3175 | to = gen_reg_rtx (GET_MODE (SET_DEST (PATTERN (insn_computes_expr)))); | |
3176 | ||
3177 | /* Generate the new insn. */ | |
3178 | /* ??? If the change fails, we return 0, even though we created | |
3179 | an insn. I think this is ok. */ | |
9e6a5703 JC |
3180 | new_insn |
3181 | = emit_insn_after (gen_rtx_SET (VOIDmode, to, | |
3182 | SET_DEST (PATTERN (insn_computes_expr))), | |
7506f491 DE |
3183 | insn_computes_expr); |
3184 | /* Keep block number table up to date. */ | |
3185 | set_block_num (new_insn, BLOCK_NUM (insn_computes_expr)); | |
3186 | /* Keep register set table up to date. */ | |
3187 | record_one_set (REGNO (to), new_insn); | |
3188 | ||
3189 | gcse_create_count++; | |
3190 | if (gcse_file != NULL) | |
3191 | { | |
3192 | fprintf (gcse_file, "GCSE: Creating insn %d to copy value of reg %d, computed in insn %d,\n", | |
3193 | INSN_UID (NEXT_INSN (insn_computes_expr)), | |
3194 | REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr)))), | |
3195 | INSN_UID (insn_computes_expr)); | |
3196 | fprintf (gcse_file, " into newly allocated reg %d\n", REGNO (to)); | |
3197 | } | |
3198 | ||
3199 | pat = PATTERN (insn); | |
3200 | ||
3201 | /* Do register replacement for INSN. */ | |
3202 | changed = validate_change (insn, &SET_SRC (pat), | |
3203 | SET_DEST (PATTERN (NEXT_INSN (insn_computes_expr))), | |
3204 | 0); | |
3205 | ||
3206 | /* We should be able to ignore the return code from validate_change but | |
3207 | to play it safe we check. */ | |
3208 | if (changed) | |
3209 | { | |
3210 | gcse_subst_count++; | |
3211 | if (gcse_file != NULL) | |
3212 | { | |
3213 | fprintf (gcse_file, "GCSE: Replacing the source in insn %d with reg %d set in insn %d\n", | |
3214 | INSN_UID (insn), | |
3215 | REGNO (SET_DEST (PATTERN (NEXT_INSN (insn_computes_expr)))), | |
3216 | INSN_UID (insn_computes_expr)); | |
3217 | } | |
3218 | ||
3219 | } | |
3220 | } | |
3221 | ||
3222 | return changed; | |
3223 | } | |
3224 | ||
3225 | /* Perform classic GCSE. | |
3226 | This is called by one_classic_gcse_pass after all the dataflow analysis | |
3227 | has been done. | |
3228 | ||
3229 | The result is non-zero if a change was made. */ | |
3230 | ||
3231 | static int | |
3232 | classic_gcse () | |
3233 | { | |
3234 | int bb, changed; | |
3235 | rtx insn; | |
3236 | ||
3237 | /* Note we start at block 1. */ | |
3238 | ||
3239 | changed = 0; | |
3240 | for (bb = 1; bb < n_basic_blocks; bb++) | |
3241 | { | |
3242 | /* Reset tables used to keep track of what's still valid [since the | |
3243 | start of the block]. */ | |
3244 | reset_opr_set_tables (); | |
3245 | ||
3b413743 RH |
3246 | for (insn = BLOCK_HEAD (bb); |
3247 | insn != NULL && insn != NEXT_INSN (BLOCK_END (bb)); | |
7506f491 DE |
3248 | insn = NEXT_INSN (insn)) |
3249 | { | |
3250 | /* Is insn of form (set (pseudo-reg) ...)? */ | |
3251 | ||
3252 | if (GET_CODE (insn) == INSN | |
3253 | && GET_CODE (PATTERN (insn)) == SET | |
3254 | && GET_CODE (SET_DEST (PATTERN (insn))) == REG | |
3255 | && REGNO (SET_DEST (PATTERN (insn))) >= FIRST_PSEUDO_REGISTER) | |
3256 | { | |
3257 | rtx pat = PATTERN (insn); | |
3258 | rtx src = SET_SRC (pat); | |
3259 | struct expr *expr; | |
3260 | ||
3261 | if (want_to_gcse_p (src) | |
3262 | /* Is the expression recorded? */ | |
3263 | && ((expr = lookup_expr (src)) != NULL) | |
3264 | /* Is the expression available [at the start of the | |
3265 | block]? */ | |
3266 | && TEST_BIT (ae_in[bb], expr->bitmap_index) | |
3267 | /* Are the operands unchanged since the start of the | |
3268 | block? */ | |
3269 | && oprs_not_set_p (src, insn)) | |
3270 | changed |= handle_avail_expr (insn, expr); | |
3271 | } | |
3272 | ||
3273 | /* Keep track of everything modified by this insn. */ | |
3274 | /* ??? Need to be careful w.r.t. mods done to INSN. */ | |
3275 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
3276 | mark_oprs_set (insn); | |
3277 | } | |
3278 | } | |
3279 | ||
3280 | return changed; | |
3281 | } | |
3282 | ||
3283 | /* Top level routine to perform one classic GCSE pass. | |
3284 | ||
3285 | Return non-zero if a change was made. */ | |
3286 | ||
3287 | static int | |
3288 | one_classic_gcse_pass (f, pass) | |
3289 | rtx f; | |
3290 | int pass; | |
3291 | { | |
3292 | int changed = 0; | |
3293 | ||
3294 | gcse_subst_count = 0; | |
3295 | gcse_create_count = 0; | |
3296 | ||
3297 | alloc_expr_hash_table (max_cuid); | |
3298 | alloc_rd_mem (n_basic_blocks, max_cuid); | |
3299 | compute_expr_hash_table (f); | |
3300 | if (gcse_file) | |
3301 | dump_hash_table (gcse_file, "Expression", expr_hash_table, | |
3302 | expr_hash_table_size, n_exprs); | |
3303 | if (n_exprs > 0) | |
3304 | { | |
3305 | compute_kill_rd (); | |
3306 | compute_rd (); | |
3307 | alloc_avail_expr_mem (n_basic_blocks, n_exprs); | |
3308 | compute_ae_gen (); | |
3309 | compute_ae_kill (); | |
3310 | compute_available (); | |
3311 | changed = classic_gcse (); | |
3312 | free_avail_expr_mem (); | |
3313 | } | |
3314 | free_rd_mem (); | |
3315 | free_expr_hash_table (); | |
3316 | ||
3317 | if (gcse_file) | |
3318 | { | |
3319 | fprintf (gcse_file, "\n"); | |
3320 | fprintf (gcse_file, "GCSE of %s, pass %d: %d bytes needed, %d substs, %d insns created\n", | |
3321 | current_function_name, pass, | |
3322 | bytes_used, gcse_subst_count, gcse_create_count); | |
3323 | } | |
3324 | ||
3325 | return changed; | |
3326 | } | |
3327 | \f | |
3328 | /* Compute copy/constant propagation working variables. */ | |
3329 | ||
3330 | /* Local properties of assignments. */ | |
3331 | ||
3332 | static sbitmap *cprop_pavloc; | |
3333 | static sbitmap *cprop_absaltered; | |
3334 | ||
3335 | /* Global properties of assignments (computed from the local properties). */ | |
3336 | ||
3337 | static sbitmap *cprop_avin; | |
3338 | static sbitmap *cprop_avout; | |
3339 | ||
3340 | /* Allocate vars used for copy/const propagation. | |
3341 | N_BLOCKS is the number of basic blocks. | |
3342 | N_SETS is the number of sets. */ | |
3343 | ||
3344 | static void | |
3345 | alloc_cprop_mem (n_blocks, n_sets) | |
3346 | int n_blocks, n_sets; | |
3347 | { | |
3348 | cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets); | |
3349 | cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets); | |
3350 | ||
3351 | cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets); | |
3352 | cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets); | |
3353 | } | |
3354 | ||
3355 | /* Free vars used by copy/const propagation. */ | |
3356 | ||
3357 | static void | |
3358 | free_cprop_mem () | |
3359 | { | |
3360 | free (cprop_pavloc); | |
3361 | free (cprop_absaltered); | |
3362 | free (cprop_avin); | |
3363 | free (cprop_avout); | |
3364 | } | |
3365 | ||
3366 | /* Dump copy/const propagation data. */ | |
3367 | ||
50b2596f | 3368 | void |
7506f491 DE |
3369 | dump_cprop_data (file) |
3370 | FILE *file; | |
3371 | { | |
3372 | dump_sbitmap_vector (file, "CPROP partially locally available sets", "BB", | |
3373 | cprop_pavloc, n_basic_blocks); | |
3374 | dump_sbitmap_vector (file, "CPROP absolutely altered sets", "BB", | |
3375 | cprop_absaltered, n_basic_blocks); | |
3376 | ||
3377 | dump_sbitmap_vector (file, "CPROP available incoming sets", "BB", | |
3378 | cprop_avin, n_basic_blocks); | |
3379 | dump_sbitmap_vector (file, "CPROP available outgoing sets", "BB", | |
3380 | cprop_avout, n_basic_blocks); | |
3381 | } | |
3382 | ||
3383 | /* For each block, compute whether X is transparent. | |
3384 | X is either an expression or an assignment [though we don't care which, | |
3385 | for this context an assignment is treated as an expression]. | |
3386 | For each block where an element of X is modified, set (SET_P == 1) or reset | |
3387 | (SET_P == 0) the INDX bit in BMAP. */ | |
3388 | ||
3389 | static void | |
3390 | compute_transp (x, indx, bmap, set_p) | |
3391 | rtx x; | |
3392 | int indx; | |
3393 | sbitmap *bmap; | |
3394 | int set_p; | |
3395 | { | |
3396 | int bb,i; | |
3397 | enum rtx_code code; | |
3398 | char *fmt; | |
3399 | ||
3400 | /* repeat is used to turn tail-recursion into iteration. */ | |
3401 | repeat: | |
3402 | ||
3403 | if (x == 0) | |
3404 | return; | |
3405 | ||
3406 | code = GET_CODE (x); | |
3407 | switch (code) | |
3408 | { | |
3409 | case REG: | |
3410 | { | |
3411 | reg_set *r; | |
3412 | int regno = REGNO (x); | |
3413 | ||
3414 | if (set_p) | |
3415 | { | |
3416 | if (regno < FIRST_PSEUDO_REGISTER) | |
3417 | { | |
3418 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3419 | if (TEST_BIT (reg_set_in_block[bb], regno)) | |
3420 | SET_BIT (bmap[bb], indx); | |
3421 | } | |
3422 | else | |
3423 | { | |
3424 | for (r = reg_set_table[regno]; r != NULL; r = r->next) | |
3425 | { | |
3426 | bb = BLOCK_NUM (r->insn); | |
3427 | SET_BIT (bmap[bb], indx); | |
3428 | } | |
3429 | } | |
3430 | } | |
3431 | else | |
3432 | { | |
3433 | if (regno < FIRST_PSEUDO_REGISTER) | |
3434 | { | |
3435 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3436 | if (TEST_BIT (reg_set_in_block[bb], regno)) | |
3437 | RESET_BIT (bmap[bb], indx); | |
3438 | } | |
3439 | else | |
3440 | { | |
3441 | for (r = reg_set_table[regno]; r != NULL; r = r->next) | |
3442 | { | |
3443 | bb = BLOCK_NUM (r->insn); | |
3444 | RESET_BIT (bmap[bb], indx); | |
3445 | } | |
3446 | } | |
3447 | } | |
3448 | return; | |
3449 | } | |
3450 | ||
3451 | case MEM: | |
3452 | if (set_p) | |
3453 | { | |
3454 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3455 | if (mem_set_in_block[bb]) | |
3456 | SET_BIT (bmap[bb], indx); | |
3457 | } | |
3458 | else | |
3459 | { | |
3460 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3461 | if (mem_set_in_block[bb]) | |
3462 | RESET_BIT (bmap[bb], indx); | |
3463 | } | |
3464 | x = XEXP (x, 0); | |
3465 | goto repeat; | |
3466 | ||
3467 | case PC: | |
3468 | case CC0: /*FIXME*/ | |
3469 | case CONST: | |
3470 | case CONST_INT: | |
3471 | case CONST_DOUBLE: | |
3472 | case SYMBOL_REF: | |
3473 | case LABEL_REF: | |
3474 | case ADDR_VEC: | |
3475 | case ADDR_DIFF_VEC: | |
3476 | return; | |
3477 | ||
3478 | default: | |
3479 | break; | |
3480 | } | |
3481 | ||
3482 | i = GET_RTX_LENGTH (code) - 1; | |
3483 | fmt = GET_RTX_FORMAT (code); | |
3484 | for (; i >= 0; i--) | |
3485 | { | |
3486 | if (fmt[i] == 'e') | |
3487 | { | |
3488 | rtx tem = XEXP (x, i); | |
3489 | ||
3490 | /* If we are about to do the last recursive call | |
3491 | needed at this level, change it into iteration. | |
3492 | This function is called enough to be worth it. */ | |
3493 | if (i == 0) | |
3494 | { | |
3495 | x = tem; | |
3496 | goto repeat; | |
3497 | } | |
3498 | compute_transp (tem, indx, bmap, set_p); | |
3499 | } | |
3500 | else if (fmt[i] == 'E') | |
3501 | { | |
3502 | int j; | |
3503 | for (j = 0; j < XVECLEN (x, i); j++) | |
3504 | compute_transp (XVECEXP (x, i, j), indx, bmap, set_p); | |
3505 | } | |
3506 | } | |
3507 | } | |
3508 | ||
3509 | static void | |
3510 | compute_cprop_local_properties () | |
3511 | { | |
3512 | int i; | |
3513 | ||
3514 | sbitmap_vector_zero (cprop_absaltered, n_basic_blocks); | |
3515 | sbitmap_vector_zero (cprop_pavloc, n_basic_blocks); | |
3516 | ||
3517 | for (i = 0; i < set_hash_table_size; i++) | |
3518 | { | |
3519 | struct expr *expr; | |
3520 | ||
3521 | for (expr = set_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
3522 | { | |
3523 | struct occr *occr; | |
3524 | int indx = expr->bitmap_index; | |
3525 | ||
3526 | /* The assignment is absolutely altered if any operand is modified | |
3527 | by this block [excluding the assignment itself]. | |
3528 | We start by assuming all are transparent [none are killed], and | |
3529 | then setting the bits for those that are. */ | |
3530 | ||
3531 | compute_transp (expr->expr, indx, cprop_absaltered, 1); | |
3532 | ||
3533 | /* The occurrences recorded in avail_occr are exactly those that | |
3534 | we want to set to non-zero in PAVLOC. */ | |
3535 | ||
3536 | for (occr = expr->avail_occr; occr != NULL; occr = occr->next) | |
3537 | { | |
3538 | int bb = BLOCK_NUM (occr->insn); | |
3539 | SET_BIT (cprop_pavloc[bb], indx); | |
3540 | } | |
3541 | } | |
3542 | } | |
3543 | } | |
3544 | ||
3545 | static void | |
3546 | compute_cprop_avinout () | |
3547 | { | |
3548 | int bb, changed, passes; | |
3549 | ||
3550 | sbitmap_zero (cprop_avin[0]); | |
3551 | sbitmap_vector_ones (cprop_avout, n_basic_blocks); | |
3552 | ||
3553 | passes = 0; | |
3554 | changed = 1; | |
3555 | while (changed) | |
3556 | { | |
3557 | changed = 0; | |
3558 | for (bb = 0; bb < n_basic_blocks; bb++) | |
3559 | { | |
3560 | if (bb != 0) | |
3561 | sbitmap_intersect_of_predecessors (cprop_avin[bb], cprop_avout, | |
3562 | bb, s_preds); | |
3563 | changed |= sbitmap_union_of_diff (cprop_avout[bb], | |
3564 | cprop_pavloc[bb], | |
3565 | cprop_avin[bb], | |
3566 | cprop_absaltered[bb]); | |
3567 | } | |
3568 | passes++; | |
3569 | } | |
3570 | ||
3571 | if (gcse_file) | |
3572 | fprintf (gcse_file, "cprop avail expr computation: %d passes\n", passes); | |
3573 | } | |
3574 | ||
3575 | /* Top level routine to do the dataflow analysis needed by copy/const | |
3576 | propagation. */ | |
3577 | ||
3578 | static void | |
3579 | compute_cprop_data () | |
3580 | { | |
3581 | compute_cprop_local_properties (); | |
3582 | compute_cprop_avinout (); | |
3583 | } | |
3584 | \f | |
3585 | /* Copy/constant propagation. */ | |
3586 | ||
3587 | struct reg_use { | |
3588 | rtx reg_rtx; | |
3589 | }; | |
3590 | ||
3591 | /* Maximum number of register uses in an insn that we handle. */ | |
3592 | #define MAX_USES 8 | |
3593 | ||
3594 | /* Table of uses found in an insn. | |
3595 | Allocated statically to avoid alloc/free complexity and overhead. */ | |
3596 | static struct reg_use reg_use_table[MAX_USES]; | |
3597 | ||
3598 | /* Index into `reg_use_table' while building it. */ | |
3599 | static int reg_use_count; | |
3600 | ||
3601 | /* Set up a list of register numbers used in INSN. | |
3602 | The found uses are stored in `reg_use_table'. | |
3603 | `reg_use_count' is initialized to zero before entry, and | |
3604 | contains the number of uses in the table upon exit. | |
3605 | ||
3606 | ??? If a register appears multiple times we will record it multiple | |
3607 | times. This doesn't hurt anything but it will slow things down. */ | |
3608 | ||
3609 | static void | |
3610 | find_used_regs (x) | |
3611 | rtx x; | |
3612 | { | |
3613 | int i; | |
3614 | enum rtx_code code; | |
3615 | char *fmt; | |
3616 | ||
3617 | /* repeat is used to turn tail-recursion into iteration. */ | |
3618 | repeat: | |
3619 | ||
3620 | if (x == 0) | |
3621 | return; | |
3622 | ||
3623 | code = GET_CODE (x); | |
3624 | switch (code) | |
3625 | { | |
3626 | case REG: | |
3627 | if (reg_use_count == MAX_USES) | |
3628 | return; | |
3629 | reg_use_table[reg_use_count].reg_rtx = x; | |
3630 | reg_use_count++; | |
3631 | return; | |
3632 | ||
3633 | case MEM: | |
3634 | x = XEXP (x, 0); | |
3635 | goto repeat; | |
3636 | ||
3637 | case PC: | |
3638 | case CC0: | |
3639 | case CONST: | |
3640 | case CONST_INT: | |
3641 | case CONST_DOUBLE: | |
3642 | case SYMBOL_REF: | |
3643 | case LABEL_REF: | |
3644 | case CLOBBER: | |
3645 | case ADDR_VEC: | |
3646 | case ADDR_DIFF_VEC: | |
3647 | case ASM_INPUT: /*FIXME*/ | |
3648 | return; | |
3649 | ||
3650 | case SET: | |
3651 | if (GET_CODE (SET_DEST (x)) == MEM) | |
3652 | find_used_regs (SET_DEST (x)); | |
3653 | x = SET_SRC (x); | |
3654 | goto repeat; | |
3655 | ||
3656 | default: | |
3657 | break; | |
3658 | } | |
3659 | ||
3660 | /* Recursively scan the operands of this expression. */ | |
3661 | ||
3662 | fmt = GET_RTX_FORMAT (code); | |
3663 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
3664 | { | |
3665 | if (fmt[i] == 'e') | |
3666 | { | |
3667 | /* If we are about to do the last recursive call | |
3668 | needed at this level, change it into iteration. | |
3669 | This function is called enough to be worth it. */ | |
3670 | if (i == 0) | |
3671 | { | |
3672 | x = XEXP (x, 0); | |
3673 | goto repeat; | |
3674 | } | |
3675 | find_used_regs (XEXP (x, i)); | |
3676 | } | |
3677 | else if (fmt[i] == 'E') | |
3678 | { | |
3679 | int j; | |
3680 | for (j = 0; j < XVECLEN (x, i); j++) | |
3681 | find_used_regs (XVECEXP (x, i, j)); | |
3682 | } | |
3683 | } | |
3684 | } | |
3685 | ||
3686 | /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO. | |
3687 | Returns non-zero is successful. */ | |
3688 | ||
3689 | static int | |
3690 | try_replace_reg (from, to, insn) | |
3691 | rtx from, to, insn; | |
3692 | { | |
3693 | return validate_replace_src (from, to, insn); | |
3694 | } | |
3695 | ||
3696 | /* Find a set of REGNO that is available on entry to INSN's block. | |
3697 | Returns NULL if not found. */ | |
3698 | ||
3699 | static struct expr * | |
3700 | find_avail_set (regno, insn) | |
3701 | int regno; | |
3702 | rtx insn; | |
3703 | { | |
3704 | struct expr *set = lookup_set (regno, NULL_RTX); | |
3705 | ||
3706 | while (set) | |
3707 | { | |
3708 | if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index)) | |
3709 | break; | |
3710 | set = next_set (regno, set); | |
3711 | } | |
3712 | ||
3713 | return set; | |
3714 | } | |
3715 | ||
3716 | /* Perform constant and copy propagation on INSN. | |
3717 | The result is non-zero if a change was made. */ | |
3718 | ||
3719 | static int | |
3720 | cprop_insn (insn) | |
3721 | rtx insn; | |
3722 | { | |
3723 | struct reg_use *reg_used; | |
3724 | int changed = 0; | |
3725 | ||
3726 | /* ??? For now only propagate into SETs. */ | |
3727 | if (GET_CODE (insn) != INSN | |
3728 | || GET_CODE (PATTERN (insn)) != SET) | |
3729 | return 0; | |
3730 | ||
3731 | reg_use_count = 0; | |
3732 | find_used_regs (PATTERN (insn)); | |
3733 | ||
3734 | reg_used = ®_use_table[0]; | |
3735 | for ( ; reg_use_count > 0; reg_used++, reg_use_count--) | |
3736 | { | |
3737 | rtx pat, src; | |
3738 | struct expr *set; | |
3739 | int regno = REGNO (reg_used->reg_rtx); | |
3740 | ||
3741 | /* Ignore registers created by GCSE. | |
3742 | We do this because ... */ | |
3743 | if (regno >= max_gcse_regno) | |
3744 | continue; | |
3745 | ||
3746 | /* If the register has already been set in this block, there's | |
3747 | nothing we can do. */ | |
3748 | if (! oprs_not_set_p (reg_used->reg_rtx, insn)) | |
3749 | continue; | |
3750 | ||
3751 | /* Find an assignment that sets reg_used and is available | |
3752 | at the start of the block. */ | |
3753 | set = find_avail_set (regno, insn); | |
3754 | if (! set) | |
3755 | continue; | |
3756 | ||
3757 | pat = set->expr; | |
3758 | /* ??? We might be able to handle PARALLELs. Later. */ | |
3759 | if (GET_CODE (pat) != SET) | |
3760 | abort (); | |
3761 | src = SET_SRC (pat); | |
3762 | ||
3763 | if (GET_CODE (src) == CONST_INT) | |
3764 | { | |
3765 | if (try_replace_reg (reg_used->reg_rtx, src, insn)) | |
3766 | { | |
3767 | changed = 1; | |
3768 | const_prop_count++; | |
3769 | if (gcse_file != NULL) | |
3770 | { | |
3771 | fprintf (gcse_file, "CONST-PROP: Replacing reg %d in insn %d with constant ", | |
3772 | regno, INSN_UID (insn)); | |
3773 | fprintf (gcse_file, HOST_WIDE_INT_PRINT_DEC, INTVAL (src)); | |
3774 | fprintf (gcse_file, "\n"); | |
3775 | } | |
3776 | ||
3777 | /* The original insn setting reg_used may or may not now be | |
3778 | deletable. We leave the deletion to flow. */ | |
3779 | } | |
3780 | } | |
3781 | else if (GET_CODE (src) == REG | |
3782 | && REGNO (src) >= FIRST_PSEUDO_REGISTER | |
3783 | && REGNO (src) != regno) | |
3784 | { | |
3785 | /* We know the set is available. | |
3786 | Now check that SET_SRC is ANTLOC (i.e. none of the source operands | |
3787 | have changed since the start of the block). */ | |
3788 | if (oprs_not_set_p (src, insn)) | |
3789 | { | |
3790 | if (try_replace_reg (reg_used->reg_rtx, src, insn)) | |
3791 | { | |
3792 | changed = 1; | |
3793 | copy_prop_count++; | |
3794 | if (gcse_file != NULL) | |
3795 | { | |
3796 | fprintf (gcse_file, "COPY-PROP: Replacing reg %d in insn %d with reg %d\n", | |
3797 | regno, INSN_UID (insn), REGNO (src)); | |
3798 | } | |
3799 | ||
3800 | /* The original insn setting reg_used may or may not now be | |
3801 | deletable. We leave the deletion to flow. */ | |
3802 | /* FIXME: If it turns out that the insn isn't deletable, | |
3803 | then we may have unnecessarily extended register lifetimes | |
3804 | and made things worse. */ | |
3805 | } | |
3806 | } | |
3807 | } | |
3808 | } | |
3809 | ||
3810 | return changed; | |
3811 | } | |
3812 | ||
3813 | /* Forward propagate copies. | |
3814 | This includes copies and constants. | |
3815 | Return non-zero if a change was made. */ | |
3816 | ||
3817 | static int | |
3818 | cprop () | |
3819 | { | |
3820 | int bb, changed; | |
3821 | rtx insn; | |
3822 | ||
3823 | /* Note we start at block 1. */ | |
3824 | ||
3825 | changed = 0; | |
3826 | for (bb = 1; bb < n_basic_blocks; bb++) | |
3827 | { | |
3828 | /* Reset tables used to keep track of what's still valid [since the | |
3829 | start of the block]. */ | |
3830 | reset_opr_set_tables (); | |
3831 | ||
3b413743 RH |
3832 | for (insn = BLOCK_HEAD (bb); |
3833 | insn != NULL && insn != NEXT_INSN (BLOCK_END (bb)); | |
7506f491 DE |
3834 | insn = NEXT_INSN (insn)) |
3835 | { | |
3836 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
3837 | { | |
3838 | changed |= cprop_insn (insn); | |
3839 | ||
3840 | /* Keep track of everything modified by this insn. */ | |
3841 | /* ??? Need to be careful w.r.t. mods done to INSN. */ | |
3842 | mark_oprs_set (insn); | |
3843 | } | |
3844 | } | |
3845 | } | |
3846 | ||
3847 | if (gcse_file != NULL) | |
3848 | fprintf (gcse_file, "\n"); | |
3849 | ||
3850 | return changed; | |
3851 | } | |
3852 | ||
3853 | /* Perform one copy/constant propagation pass. | |
3854 | F is the first insn in the function. | |
3855 | PASS is the pass count. */ | |
3856 | ||
3857 | static int | |
3858 | one_cprop_pass (f, pass) | |
3859 | rtx f; | |
3860 | int pass; | |
3861 | { | |
3862 | int changed = 0; | |
3863 | ||
3864 | const_prop_count = 0; | |
3865 | copy_prop_count = 0; | |
3866 | ||
3867 | alloc_set_hash_table (max_cuid); | |
3868 | compute_set_hash_table (f); | |
3869 | if (gcse_file) | |
3870 | dump_hash_table (gcse_file, "SET", set_hash_table, set_hash_table_size, | |
3871 | n_sets); | |
3872 | if (n_sets > 0) | |
3873 | { | |
3874 | alloc_cprop_mem (n_basic_blocks, n_sets); | |
3875 | compute_cprop_data (); | |
3876 | changed = cprop (); | |
3877 | free_cprop_mem (); | |
3878 | } | |
3879 | free_set_hash_table (); | |
3880 | ||
3881 | if (gcse_file) | |
3882 | { | |
3883 | fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, %d const props, %d copy props\n", | |
3884 | current_function_name, pass, | |
3885 | bytes_used, const_prop_count, copy_prop_count); | |
3886 | fprintf (gcse_file, "\n"); | |
3887 | } | |
3888 | ||
3889 | return changed; | |
3890 | } | |
3891 | \f | |
3892 | /* Compute PRE working variables. */ | |
3893 | ||
3894 | /* Local properties of expressions. */ | |
3895 | /* Nonzero for expressions that are transparent in the block. */ | |
3896 | static sbitmap *pre_transp; | |
3897 | /* Nonzero for expressions that are computed (available) in the block. */ | |
3898 | static sbitmap *pre_comp; | |
3899 | /* Nonzero for expressions that are locally anticipatable in the block. */ | |
3900 | static sbitmap *pre_antloc; | |
3901 | ||
3902 | /* Global properties (computed from the expression local properties). */ | |
3903 | /* Nonzero for expressions that are available on block entry/exit. */ | |
3904 | static sbitmap *pre_avin; | |
3905 | static sbitmap *pre_avout; | |
3906 | /* Nonzero for expressions that are anticipatable on block entry/exit. */ | |
3907 | static sbitmap *pre_antin; | |
3908 | static sbitmap *pre_antout; | |
3909 | /* Nonzero for expressions that are partially available on block entry/exit. */ | |
3910 | static sbitmap *pre_pavin; | |
3911 | static sbitmap *pre_pavout; | |
3912 | /* Nonzero for expressions that are "placement possible" on block entry/exit. */ | |
3913 | static sbitmap *pre_ppin; | |
3914 | static sbitmap *pre_ppout; | |
3915 | ||
5c35539b RH |
3916 | /* Nonzero for expressions that are transparent at the end of the block. |
3917 | This is only zero for expressions killed by abnormal critical edge | |
3918 | created by a calls. */ | |
3919 | static sbitmap *pre_transpout; | |
3920 | ||
7506f491 DE |
3921 | /* Used while performing PRE to denote which insns are redundant. */ |
3922 | static sbitmap pre_redundant; | |
3923 | ||
3924 | /* Allocate vars used for PRE analysis. */ | |
3925 | ||
3926 | static void | |
3927 | alloc_pre_mem (n_blocks, n_exprs) | |
3928 | int n_blocks, n_exprs; | |
3929 | { | |
3930 | pre_transp = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3931 | pre_comp = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3932 | pre_antloc = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3933 | ||
3934 | pre_avin = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3935 | pre_avout = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3936 | pre_antin = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3937 | pre_antout = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3938 | ||
3939 | pre_pavin = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3940 | pre_pavout = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3941 | pre_ppin = sbitmap_vector_alloc (n_blocks, n_exprs); | |
3942 | pre_ppout = sbitmap_vector_alloc (n_blocks, n_exprs); | |
5c35539b RH |
3943 | |
3944 | pre_transpout = sbitmap_vector_alloc (n_blocks, n_exprs); | |
7506f491 DE |
3945 | } |
3946 | ||
3947 | /* Free vars used for PRE analysis. */ | |
3948 | ||
3949 | static void | |
3950 | free_pre_mem () | |
3951 | { | |
3952 | free (pre_transp); | |
3953 | free (pre_comp); | |
3954 | free (pre_antloc); | |
7506f491 DE |
3955 | free (pre_avin); |
3956 | free (pre_avout); | |
3957 | free (pre_antin); | |
3958 | free (pre_antout); | |
3959 | ||
3960 | free (pre_pavin); | |
3961 | free (pre_pavout); | |
3962 | free (pre_ppin); | |
3963 | free (pre_ppout); | |
5c35539b | 3964 | free (pre_transpout); |
7506f491 DE |
3965 | } |
3966 | ||
3967 | /* Dump PRE data. */ | |
3968 | ||
50b2596f | 3969 | void |
7506f491 DE |
3970 | dump_pre_data (file) |
3971 | FILE *file; | |
3972 | { | |
3973 | dump_sbitmap_vector (file, "PRE locally transparent expressions", "BB", | |
3974 | pre_transp, n_basic_blocks); | |
3975 | dump_sbitmap_vector (file, "PRE locally available expressions", "BB", | |
3976 | pre_comp, n_basic_blocks); | |
3977 | dump_sbitmap_vector (file, "PRE locally anticipatable expressions", "BB", | |
3978 | pre_antloc, n_basic_blocks); | |
3979 | ||
3980 | dump_sbitmap_vector (file, "PRE available incoming expressions", "BB", | |
3981 | pre_avin, n_basic_blocks); | |
3982 | dump_sbitmap_vector (file, "PRE available outgoing expressions", "BB", | |
3983 | pre_avout, n_basic_blocks); | |
3984 | dump_sbitmap_vector (file, "PRE anticipatable incoming expressions", "BB", | |
3985 | pre_antin, n_basic_blocks); | |
3986 | dump_sbitmap_vector (file, "PRE anticipatable outgoing expressions", "BB", | |
3987 | pre_antout, n_basic_blocks); | |
3988 | ||
3989 | dump_sbitmap_vector (file, "PRE partially available incoming expressions", "BB", | |
3990 | pre_pavin, n_basic_blocks); | |
3991 | dump_sbitmap_vector (file, "PRE partially available outgoing expressions", "BB", | |
3992 | pre_pavout, n_basic_blocks); | |
3993 | dump_sbitmap_vector (file, "PRE placement possible on incoming", "BB", | |
3994 | pre_ppin, n_basic_blocks); | |
3995 | dump_sbitmap_vector (file, "PRE placement possible on outgoing", "BB", | |
3996 | pre_ppout, n_basic_blocks); | |
5c35539b RH |
3997 | |
3998 | dump_sbitmap_vector (file, "PRE transparent on outgoing", "BB", | |
3999 | pre_transpout, n_basic_blocks); | |
7506f491 DE |
4000 | } |
4001 | ||
4002 | /* Compute the local properties of each recorded expression. | |
4003 | Local properties are those that are defined by the block, irrespective | |
4004 | of other blocks. | |
4005 | ||
4006 | An expression is transparent in a block if its operands are not modified | |
4007 | in the block. | |
4008 | ||
4009 | An expression is computed (locally available) in a block if it is computed | |
4010 | at least once and expression would contain the same value if the | |
4011 | computation was moved to the end of the block. | |
4012 | ||
4013 | An expression is locally anticipatable in a block if it is computed at | |
4014 | least once and expression would contain the same value if the computation | |
4015 | was moved to the beginning of the block. */ | |
4016 | ||
4017 | static void | |
4018 | compute_pre_local_properties () | |
4019 | { | |
4020 | int i; | |
4021 | ||
4022 | sbitmap_vector_ones (pre_transp, n_basic_blocks); | |
4023 | sbitmap_vector_zero (pre_comp, n_basic_blocks); | |
4024 | sbitmap_vector_zero (pre_antloc, n_basic_blocks); | |
4025 | ||
4026 | for (i = 0; i < expr_hash_table_size; i++) | |
4027 | { | |
4028 | struct expr *expr; | |
4029 | ||
4030 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
4031 | { | |
4032 | struct occr *occr; | |
4033 | int indx = expr->bitmap_index; | |
4034 | ||
4035 | /* The expression is transparent in this block if it is not killed. | |
4036 | We start by assuming all are transparent [none are killed], and then | |
4037 | reset the bits for those that are. */ | |
4038 | ||
4039 | compute_transp (expr->expr, indx, pre_transp, 0); | |
4040 | ||
4041 | /* The occurrences recorded in antic_occr are exactly those that | |
4042 | we want to set to non-zero in ANTLOC. */ | |
4043 | ||
4044 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
4045 | { | |
4046 | int bb = BLOCK_NUM (occr->insn); | |
4047 | SET_BIT (pre_antloc[bb], indx); | |
4048 | ||
4049 | /* While we're scanning the table, this is a good place to | |
4050 | initialize this. */ | |
4051 | occr->deleted_p = 0; | |
4052 | } | |
4053 | ||
4054 | /* The occurrences recorded in avail_occr are exactly those that | |
4055 | we want to set to non-zero in COMP. */ | |
4056 | ||
4057 | for (occr = expr->avail_occr; occr != NULL; occr = occr->next) | |
4058 | { | |
4059 | int bb = BLOCK_NUM (occr->insn); | |
4060 | SET_BIT (pre_comp[bb], indx); | |
4061 | ||
4062 | /* While we're scanning the table, this is a good place to | |
4063 | initialize this. */ | |
4064 | occr->copied_p = 0; | |
4065 | } | |
4066 | ||
4067 | /* While we're scanning the table, this is a good place to | |
4068 | initialize this. */ | |
4069 | expr->reaching_reg = 0; | |
4070 | } | |
4071 | } | |
4072 | } | |
4073 | ||
4074 | /* Compute expression availability at entrance and exit of each block. */ | |
4075 | ||
4076 | static void | |
4077 | compute_pre_avinout () | |
4078 | { | |
4079 | int bb, changed, passes; | |
4080 | ||
4081 | sbitmap_zero (pre_avin[0]); | |
4082 | sbitmap_vector_ones (pre_avout, n_basic_blocks); | |
4083 | ||
4084 | passes = 0; | |
4085 | changed = 1; | |
4086 | while (changed) | |
4087 | { | |
4088 | changed = 0; | |
4089 | for (bb = 0; bb < n_basic_blocks; bb++) | |
4090 | { | |
4091 | if (bb != 0) | |
4092 | sbitmap_intersect_of_predecessors (pre_avin[bb], pre_avout, | |
4093 | bb, s_preds); | |
4094 | changed |= sbitmap_a_or_b_and_c (pre_avout[bb], pre_comp[bb], | |
4095 | pre_transp[bb], pre_avin[bb]); | |
4096 | } | |
4097 | passes++; | |
4098 | } | |
4099 | ||
4100 | if (gcse_file) | |
4101 | fprintf (gcse_file, "avail expr computation: %d passes\n", passes); | |
4102 | } | |
4103 | ||
4104 | /* Compute expression anticipatability at entrance and exit of each block. */ | |
4105 | ||
4106 | static void | |
4107 | compute_pre_antinout () | |
4108 | { | |
4109 | int bb, changed, passes; | |
4110 | ||
4111 | sbitmap_zero (pre_antout[n_basic_blocks - 1]); | |
4112 | sbitmap_vector_ones (pre_antin, n_basic_blocks); | |
4113 | ||
4114 | passes = 0; | |
4115 | changed = 1; | |
4116 | while (changed) | |
4117 | { | |
4118 | changed = 0; | |
4119 | /* We scan the blocks in the reverse order to speed up | |
4120 | the convergence. */ | |
4121 | for (bb = n_basic_blocks - 1; bb >= 0; bb--) | |
4122 | { | |
4123 | if (bb != n_basic_blocks - 1) | |
4124 | sbitmap_intersect_of_successors (pre_antout[bb], pre_antin, | |
4125 | bb, s_succs); | |
4126 | changed |= sbitmap_a_or_b_and_c (pre_antin[bb], pre_antloc[bb], | |
4127 | pre_transp[bb], pre_antout[bb]); | |
4128 | } | |
4129 | passes++; | |
4130 | } | |
4131 | ||
4132 | if (gcse_file) | |
4133 | fprintf (gcse_file, "antic expr computation: %d passes\n", passes); | |
4134 | } | |
4135 | ||
4136 | /* Compute expression partial availability at entrance and exit of | |
4137 | each block. */ | |
4138 | ||
4139 | static void | |
4140 | compute_pre_pavinout () | |
4141 | { | |
4142 | int bb, changed, passes; | |
4143 | ||
4144 | sbitmap_zero (pre_pavin[0]); | |
4145 | sbitmap_vector_zero (pre_pavout, n_basic_blocks); | |
4146 | ||
4147 | passes = 0; | |
4148 | changed = 1; | |
4149 | while (changed) | |
4150 | { | |
4151 | changed = 0; | |
4152 | for (bb = 0; bb < n_basic_blocks; bb++) | |
4153 | { | |
4154 | if (bb != 0) | |
4155 | sbitmap_union_of_predecessors (pre_pavin[bb], pre_pavout, | |
4156 | bb, s_preds); | |
4157 | changed |= sbitmap_a_or_b_and_c (pre_pavout[bb], pre_comp[bb], | |
4158 | pre_transp[bb], pre_pavin[bb]); | |
4159 | } | |
4160 | passes++; | |
4161 | } | |
4162 | ||
4163 | if (gcse_file) | |
4164 | fprintf (gcse_file, "partially avail expr computation: %d passes\n", passes); | |
4165 | } | |
4166 | ||
5c35539b RH |
4167 | /* Compute transparent outgoing information for each block. |
4168 | ||
4169 | An expression is transparent to an edge unless it is killed by | |
4170 | the edge itself. This can only happen with abnormal control flow, | |
4171 | when the edge is traversed through a call. This happens with | |
4172 | non-local labels and exceptions. | |
4173 | ||
4174 | This would not be necessary if we split the edge. While this is | |
4175 | normally impossible for abnormal critical edges, with some effort | |
4176 | it should be possible with exception handling, since we still have | |
4177 | control over which handler should be invoked. But due to increased | |
4178 | EH table sizes, this may not be worthwhile. */ | |
4179 | ||
4180 | static void | |
4181 | compute_pre_transpout () | |
4182 | { | |
4183 | int bb; | |
4184 | ||
4185 | sbitmap_vector_ones (pre_transpout, n_basic_blocks); | |
4186 | ||
4187 | for (bb = 0; bb < n_basic_blocks; ++bb) | |
4188 | { | |
4189 | int i; | |
4190 | ||
4191 | /* Note that flow inserted a nop a the end of basic blocks that | |
4192 | end in call instructions for reasons other than abnormal | |
4193 | control flow. */ | |
4194 | if (GET_CODE (BLOCK_END (bb)) != CALL_INSN) | |
4195 | continue; | |
4196 | ||
4197 | for (i = 0; i < expr_hash_table_size; i++) | |
4198 | { | |
4199 | struct expr *expr; | |
4200 | for (expr = expr_hash_table[i]; expr ; expr = expr->next_same_hash) | |
4201 | if (GET_CODE (expr->expr) == MEM) | |
4202 | { | |
4203 | rtx addr = XEXP (expr->expr, 0); | |
4204 | ||
4205 | if (GET_CODE (addr) == SYMBOL_REF | |
4206 | && CONSTANT_POOL_ADDRESS_P (addr)) | |
4207 | continue; | |
4208 | ||
4209 | /* ??? Optimally, we would use interprocedural alias | |
4210 | analysis to determine if this mem is actually killed | |
4211 | by this call. */ | |
4212 | RESET_BIT (pre_transpout[bb], expr->bitmap_index); | |
4213 | } | |
4214 | } | |
4215 | } | |
4216 | } | |
4217 | ||
7506f491 DE |
4218 | /* Compute "placement possible" information on entrance and exit of |
4219 | each block. | |
4220 | ||
4221 | From Fred Chow's Thesis: | |
4222 | A computation `e' is PP at a point `p' if it is anticipated at `p' and | |
4223 | all the anticipated e's can be rendered redundant by zero or more | |
4224 | insertions at that point and some other points in the procedure, and | |
4225 | these insertions satisfy the conditions that the insertions are always | |
4226 | at points that `e' is anticipated and the first anticipated e's after the | |
4227 | insertions are rendered redundant. */ | |
4228 | ||
4229 | static void | |
4230 | compute_pre_ppinout () | |
4231 | { | |
4232 | int bb, i, changed, size, passes; | |
4233 | ||
4234 | sbitmap_vector_ones (pre_ppin, n_basic_blocks); | |
4235 | /* ??? Inefficient as we set pre_ppin[0] twice, but simple. */ | |
4236 | sbitmap_zero (pre_ppin[0]); | |
4237 | ||
4238 | sbitmap_vector_ones (pre_ppout, n_basic_blocks); | |
4239 | /* ??? Inefficient as we set pre_ppout[n_basic_blocks-1] twice, but simple. */ | |
4240 | sbitmap_zero (pre_ppout[n_basic_blocks - 1]); | |
4241 | ||
4242 | size = pre_ppin[0]->size; | |
4243 | passes = 0; | |
4244 | changed = 1; | |
4245 | while (changed) | |
4246 | { | |
4247 | changed = 0; | |
4248 | for (bb = 1; bb < n_basic_blocks; bb++) | |
4249 | { | |
4250 | sbitmap_ptr antin = pre_antin[bb]->elms; | |
4251 | sbitmap_ptr pavin = pre_pavin[bb]->elms; | |
4252 | sbitmap_ptr antloc = pre_antloc[bb]->elms; | |
4253 | sbitmap_ptr transp = pre_transp[bb]->elms; | |
4254 | sbitmap_ptr ppout = pre_ppout[bb]->elms; | |
4255 | sbitmap_ptr ppin = pre_ppin[bb]->elms; | |
4256 | ||
4257 | for (i = 0; i < size; i++) | |
4258 | { | |
4259 | int_list_ptr pred; | |
4260 | SBITMAP_ELT_TYPE tmp = *antin & *pavin & (*antloc | (*transp & *ppout)); | |
973838fd | 4261 | SBITMAP_ELT_TYPE pred_val = (SBITMAP_ELT_TYPE) -1; |
7506f491 DE |
4262 | |
4263 | for (pred = s_preds[bb]; pred != NULL; pred = pred->next) | |
4264 | { | |
4265 | int pred_bb = INT_LIST_VAL (pred); | |
4266 | sbitmap_ptr ppout_j,avout_j; | |
4267 | ||
4268 | if (pred_bb == ENTRY_BLOCK) | |
4269 | continue; | |
4270 | ||
4271 | /* If this is a back edge, propagate info along the back | |
4272 | edge to allow for loop invariant code motion. | |
4273 | ||
4274 | See FOLLOW_BACK_EDGES at the top of this file for a longer | |
4275 | discussion about loop invariant code motion in pre. */ | |
4276 | if (! FOLLOW_BACK_EDGES | |
4277 | && (INSN_CUID (BLOCK_HEAD (bb)) | |
4278 | < INSN_CUID (BLOCK_END (pred_bb)))) | |
4279 | { | |
4280 | pred_val = 0; | |
4281 | } | |
4282 | else | |
4283 | { | |
4284 | ppout_j = pre_ppout[pred_bb]->elms + i; | |
4285 | avout_j = pre_avout[pred_bb]->elms + i; | |
4286 | pred_val &= *ppout_j | *avout_j; | |
4287 | } | |
4288 | } | |
4289 | tmp &= pred_val; | |
4290 | *ppin = tmp; | |
4291 | antin++; pavin++; antloc++; transp++; ppout++; ppin++; | |
4292 | } | |
4293 | } | |
4294 | ||
4295 | for (bb = 0; bb < n_basic_blocks - 1; bb++) | |
4296 | { | |
4297 | sbitmap_ptr ppout = pre_ppout[bb]->elms; | |
5c35539b | 4298 | sbitmap_ptr transpout = pre_transpout[bb]->elms; |
7506f491 DE |
4299 | |
4300 | for (i = 0; i < size; i++) | |
4301 | { | |
4302 | int_list_ptr succ; | |
5c35539b | 4303 | SBITMAP_ELT_TYPE tmp = *transpout; |
7506f491 DE |
4304 | |
4305 | for (succ = s_succs[bb]; succ != NULL; succ = succ->next) | |
4306 | { | |
4307 | int succ_bb = INT_LIST_VAL (succ); | |
4308 | sbitmap_ptr ppin; | |
4309 | ||
4310 | if (succ_bb == EXIT_BLOCK) | |
4311 | continue; | |
4312 | ||
4313 | ppin = pre_ppin[succ_bb]->elms + i; | |
4314 | tmp &= *ppin; | |
4315 | } | |
5c35539b | 4316 | |
7506f491 DE |
4317 | if (*ppout != tmp) |
4318 | { | |
4319 | changed = 1; | |
5c35539b | 4320 | *ppout = tmp; |
7506f491 | 4321 | } |
5c35539b RH |
4322 | |
4323 | ppout++; transpout++; | |
7506f491 DE |
4324 | } |
4325 | } | |
4326 | ||
4327 | passes++; | |
4328 | } | |
4329 | ||
4330 | if (gcse_file) | |
4331 | fprintf (gcse_file, "placement possible computation: %d passes\n", passes); | |
4332 | } | |
4333 | ||
4334 | /* Top level routine to do the dataflow analysis needed by PRE. */ | |
4335 | ||
4336 | static void | |
4337 | compute_pre_data () | |
4338 | { | |
4339 | compute_pre_local_properties (); | |
4340 | compute_pre_avinout (); | |
4341 | compute_pre_antinout (); | |
4342 | compute_pre_pavinout (); | |
5c35539b | 4343 | compute_pre_transpout (); |
7506f491 DE |
4344 | compute_pre_ppinout (); |
4345 | if (gcse_file) | |
4346 | fprintf (gcse_file, "\n"); | |
4347 | } | |
4348 | \f | |
4349 | /* PRE utilities */ | |
4350 | ||
4351 | /* Return non-zero if occurrence OCCR of expression EXPR reaches block BB. | |
4352 | ||
4353 | VISITED is a pointer to a working buffer for tracking which BB's have | |
4354 | been visited. It is NULL for the top-level call. | |
4355 | ||
4356 | We treat reaching expressions that go through blocks containing the same | |
4357 | reaching expression as "not reaching". E.g. if EXPR is generated in blocks | |
4358 | 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block | |
4359 | 2 as not reaching. The intent is to improve the probability of finding | |
4360 | only one reaching expression and to reduce register lifetimes by picking | |
4361 | the closest such expression. */ | |
4362 | ||
4363 | static int | |
4364 | pre_expr_reaches_here_p (occr, expr, bb, visited) | |
4365 | struct occr *occr; | |
4366 | struct expr *expr; | |
4367 | int bb; | |
4368 | char *visited; | |
4369 | { | |
4370 | int_list_ptr pred; | |
4371 | ||
4372 | if (visited == NULL) | |
4373 | { | |
4374 | visited = (char *) alloca (n_basic_blocks); | |
4375 | bzero (visited, n_basic_blocks); | |
4376 | } | |
4377 | ||
4378 | for (pred = s_preds[bb]; pred != NULL; pred = pred->next) | |
4379 | { | |
4380 | int pred_bb = INT_LIST_VAL (pred); | |
4381 | ||
4382 | if (pred_bb == ENTRY_BLOCK | |
4383 | /* Has predecessor has already been visited? */ | |
4384 | || visited[pred_bb]) | |
4385 | { | |
4386 | /* Nothing to do. */ | |
4387 | } | |
4388 | /* Does this predecessor generate this expression? */ | |
4389 | else if (TEST_BIT (pre_comp[pred_bb], expr->bitmap_index)) | |
4390 | { | |
4391 | /* Is this the occurrence we're looking for? | |
4392 | Note that there's only one generating occurrence per block | |
4393 | so we just need to check the block number. */ | |
4394 | if (BLOCK_NUM (occr->insn) == pred_bb) | |
4395 | return 1; | |
4396 | visited[pred_bb] = 1; | |
4397 | } | |
4398 | /* Ignore this predecessor if it kills the expression. */ | |
4399 | else if (! TEST_BIT (pre_transp[pred_bb], expr->bitmap_index)) | |
4400 | visited[pred_bb] = 1; | |
4401 | /* Neither gen nor kill. */ | |
4402 | else | |
4403 | { | |
4404 | visited[pred_bb] = 1; | |
4405 | if (pre_expr_reaches_here_p (occr, expr, pred_bb, visited)) | |
4406 | return 1; | |
4407 | } | |
4408 | } | |
4409 | ||
4410 | /* All paths have been checked. */ | |
4411 | return 0; | |
4412 | } | |
4413 | \f | |
4414 | /* Add EXPR to the end of basic block BB. */ | |
4415 | ||
4416 | static void | |
4417 | pre_insert_insn (expr, bb) | |
4418 | struct expr *expr; | |
4419 | int bb; | |
4420 | { | |
4421 | rtx insn = BLOCK_END (bb); | |
4422 | rtx new_insn; | |
4423 | rtx reg = expr->reaching_reg; | |
4424 | int regno = REGNO (reg); | |
4425 | rtx pat; | |
4426 | ||
9e6a5703 | 4427 | pat = gen_rtx_SET (VOIDmode, reg, copy_rtx (expr->expr)); |
7506f491 DE |
4428 | |
4429 | /* If the last insn is a jump, insert EXPR in front [taking care to | |
4430 | handle cc0, etc. properly]. */ | |
4431 | ||
4432 | if (GET_CODE (insn) == JUMP_INSN) | |
4433 | { | |
50b2596f | 4434 | #ifdef HAVE_cc0 |
7506f491 | 4435 | rtx note; |
50b2596f | 4436 | #endif |
7506f491 DE |
4437 | |
4438 | /* If this is a jump table, then we can't insert stuff here. Since | |
4439 | we know the previous real insn must be the tablejump, we insert | |
4440 | the new instruction just before the tablejump. */ | |
4441 | if (GET_CODE (PATTERN (insn)) == ADDR_VEC | |
4442 | || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) | |
4443 | insn = prev_real_insn (insn); | |
4444 | ||
4445 | #ifdef HAVE_cc0 | |
4446 | /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts | |
4447 | if cc0 isn't set. */ | |
4448 | note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX); | |
4449 | if (note) | |
4450 | insn = XEXP (note, 0); | |
4451 | else | |
4452 | { | |
4453 | rtx maybe_cc0_setter = prev_nonnote_insn (insn); | |
4454 | if (maybe_cc0_setter | |
4455 | && GET_RTX_CLASS (GET_CODE (maybe_cc0_setter)) == 'i' | |
4456 | && sets_cc0_p (PATTERN (maybe_cc0_setter))) | |
4457 | insn = maybe_cc0_setter; | |
4458 | } | |
4459 | #endif | |
4460 | /* FIXME: What if something in cc0/jump uses value set in new insn? */ | |
4461 | new_insn = emit_insn_before (pat, insn); | |
aeb2f500 | 4462 | add_label_notes (SET_SRC (pat), new_insn); |
7506f491 DE |
4463 | if (BLOCK_HEAD (bb) == insn) |
4464 | BLOCK_HEAD (bb) = new_insn; | |
3947e2f9 RH |
4465 | } |
4466 | /* Likewise if the last insn is a call, as will happen in the presence | |
4467 | of exception handling. */ | |
5c35539b | 4468 | else if (GET_CODE (insn) == CALL_INSN) |
3947e2f9 RH |
4469 | { |
4470 | HARD_REG_SET parm_regs; | |
4471 | int nparm_regs; | |
4472 | rtx p; | |
4473 | ||
4474 | /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers, | |
4475 | we search backward and place the instructions before the first | |
4476 | parameter is loaded. Do this for everyone for consistency and a | |
4477 | presumtion that we'll get better code elsewhere as well. */ | |
4478 | ||
4479 | /* It should always be the case that we can put these instructions | |
4480 | anywhere in the basic block. Check this. */ | |
1bba6199 RH |
4481 | /* ??? Well, it would be the case if we'd split all critical edges. |
4482 | Since we didn't, we may very well abort. */ | |
3947e2f9 RH |
4483 | if (!TEST_BIT (pre_antloc[bb], expr->bitmap_index) |
4484 | && !TEST_BIT (pre_transp[bb], expr->bitmap_index)) | |
4485 | abort (); | |
4486 | ||
4487 | /* Since different machines initialize their parameter registers | |
4488 | in different orders, assume nothing. Collect the set of all | |
4489 | parameter registers. */ | |
4490 | CLEAR_HARD_REG_SET (parm_regs); | |
4491 | nparm_regs = 0; | |
4492 | for (p = CALL_INSN_FUNCTION_USAGE (insn); p ; p = XEXP (p, 1)) | |
4493 | if (GET_CODE (XEXP (p, 0)) == USE | |
4494 | && GET_CODE (XEXP (XEXP (p, 0), 0)) == REG) | |
4495 | { | |
4496 | int regno = REGNO (XEXP (XEXP (p, 0), 0)); | |
4497 | if (regno >= FIRST_PSEUDO_REGISTER) | |
5c35539b | 4498 | abort (); |
3947e2f9 RH |
4499 | SET_HARD_REG_BIT (parm_regs, regno); |
4500 | nparm_regs++; | |
4501 | } | |
4502 | ||
4503 | /* Search backward for the first set of a register in this set. */ | |
4504 | while (nparm_regs && BLOCK_HEAD (bb) != insn) | |
4505 | { | |
4506 | insn = PREV_INSN (insn); | |
4507 | p = single_set (insn); | |
4508 | if (p && GET_CODE (SET_DEST (p)) == REG | |
4509 | && REGNO (SET_DEST (p)) < FIRST_PSEUDO_REGISTER | |
4510 | && TEST_HARD_REG_BIT (parm_regs, REGNO (SET_DEST (p)))) | |
4511 | { | |
4512 | CLEAR_HARD_REG_BIT (parm_regs, REGNO (SET_DEST (p))); | |
4513 | nparm_regs--; | |
4514 | } | |
4515 | } | |
4516 | ||
4517 | new_insn = emit_insn_before (pat, insn); | |
4518 | if (BLOCK_HEAD (bb) == insn) | |
4519 | BLOCK_HEAD (bb) = new_insn; | |
7506f491 DE |
4520 | } |
4521 | else | |
4522 | { | |
4523 | new_insn = emit_insn_after (pat, insn); | |
aeb2f500 | 4524 | add_label_notes (SET_SRC (pat), new_insn); |
7506f491 | 4525 | BLOCK_END (bb) = new_insn; |
7506f491 DE |
4526 | } |
4527 | ||
3947e2f9 RH |
4528 | /* Keep block number table up to date. */ |
4529 | set_block_num (new_insn, bb); | |
4530 | /* Keep register set table up to date. */ | |
4531 | record_one_set (regno, new_insn); | |
4532 | ||
7506f491 DE |
4533 | gcse_create_count++; |
4534 | ||
4535 | if (gcse_file) | |
4536 | { | |
4537 | fprintf (gcse_file, "PRE: end of bb %d, insn %d, copying expression %d to reg %d\n", | |
4538 | bb, INSN_UID (new_insn), expr->bitmap_index, regno); | |
4539 | } | |
4540 | } | |
4541 | ||
4542 | /* Insert partially redundant expressions at the ends of appropriate basic | |
4543 | blocks making them now redundant. */ | |
4544 | ||
4545 | static void | |
4546 | pre_insert (index_map) | |
4547 | struct expr **index_map; | |
4548 | { | |
4549 | int bb, i, size; | |
4550 | ||
4551 | /* Compute INSERT = PPOUT & (~AVOUT) & (~PPIN | ~TRANSP) for each | |
4552 | expression. Where INSERT == TRUE, add the expression at the end of | |
4553 | the basic block. */ | |
4554 | ||
4555 | size = pre_ppout[0]->size; | |
4556 | for (bb = 0; bb < n_basic_blocks; bb++) | |
4557 | { | |
4558 | int indx; | |
4559 | sbitmap_ptr ppout = pre_ppout[bb]->elms; | |
4560 | sbitmap_ptr avout = pre_avout[bb]->elms; | |
4561 | sbitmap_ptr ppin = pre_ppin[bb]->elms; | |
4562 | sbitmap_ptr transp = pre_transp[bb]->elms; | |
4563 | ||
4564 | for (i = indx = 0; | |
4565 | i < size; | |
4566 | i++, indx += SBITMAP_ELT_BITS, ppout++, avout++, ppin++, transp++) | |
4567 | { | |
4568 | int j; | |
4569 | SBITMAP_ELT_TYPE insert = *ppout & (~*avout) & (~*ppin | ~*transp); | |
4570 | ||
4571 | for (j = indx; insert != 0 && j < n_exprs; j++, insert >>= 1) | |
4572 | { | |
4573 | if ((insert & 1) != 0 | |
4574 | /* If the basic block isn't reachable, PPOUT will be TRUE. | |
4575 | However, we don't want to insert a copy here because the | |
4576 | expression may not really be redundant. So only insert | |
4577 | an insn if the expression was deleted. */ | |
4578 | && index_map[j]->reaching_reg != NULL) | |
4579 | pre_insert_insn (index_map[j], bb); | |
4580 | } | |
4581 | } | |
4582 | } | |
4583 | } | |
4584 | ||
4585 | /* Copy the result of INSN to REG. | |
4586 | INDX is the expression number. */ | |
4587 | ||
4588 | static void | |
4589 | pre_insert_copy_insn (expr, insn) | |
4590 | struct expr *expr; | |
4591 | rtx insn; | |
4592 | { | |
4593 | rtx reg = expr->reaching_reg; | |
4594 | int regno = REGNO (reg); | |
4595 | int indx = expr->bitmap_index; | |
4596 | rtx set = single_set (insn); | |
4597 | rtx new_insn; | |
4598 | ||
4599 | if (!set) | |
4600 | abort (); | |
9e6a5703 | 4601 | new_insn = emit_insn_after (gen_rtx_SET (VOIDmode, reg, SET_DEST (set)), |
7506f491 DE |
4602 | insn); |
4603 | /* Keep block number table up to date. */ | |
4604 | set_block_num (new_insn, BLOCK_NUM (insn)); | |
4605 | /* Keep register set table up to date. */ | |
4606 | record_one_set (regno, new_insn); | |
4607 | ||
4608 | gcse_create_count++; | |
4609 | ||
4610 | if (gcse_file) | |
4611 | { | |
4612 | fprintf (gcse_file, "PRE: bb %d, insn %d, copying expression %d in insn %d to reg %d\n", | |
4613 | BLOCK_NUM (insn), INSN_UID (new_insn), indx, INSN_UID (insn), regno); | |
4614 | } | |
4615 | } | |
4616 | ||
4617 | /* Copy available expressions that reach the redundant expression | |
4618 | to `reaching_reg'. */ | |
4619 | ||
4620 | static void | |
4621 | pre_insert_copies () | |
4622 | { | |
4623 | int i; | |
4624 | ||
4625 | /* For each available expression in the table, copy the result to | |
4626 | `reaching_reg' if the expression reaches a deleted one. | |
4627 | ||
4628 | ??? The current algorithm is rather brute force. | |
4629 | Need to do some profiling. */ | |
4630 | ||
4631 | for (i = 0; i < expr_hash_table_size; i++) | |
4632 | { | |
4633 | struct expr *expr; | |
4634 | ||
4635 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
4636 | { | |
4637 | struct occr *occr; | |
4638 | ||
4639 | /* If the basic block isn't reachable, PPOUT will be TRUE. | |
4640 | However, we don't want to insert a copy here because the | |
4641 | expression may not really be redundant. So only insert | |
4642 | an insn if the expression was deleted. | |
4643 | This test also avoids further processing if the expression | |
4644 | wasn't deleted anywhere. */ | |
4645 | if (expr->reaching_reg == NULL) | |
4646 | continue; | |
4647 | ||
4648 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
4649 | { | |
4650 | struct occr *avail; | |
4651 | ||
4652 | if (! occr->deleted_p) | |
4653 | continue; | |
4654 | ||
4655 | for (avail = expr->avail_occr; avail != NULL; avail = avail->next) | |
4656 | { | |
4657 | rtx insn = avail->insn; | |
4658 | ||
4659 | /* No need to handle this one if handled already. */ | |
4660 | if (avail->copied_p) | |
4661 | continue; | |
4662 | /* Don't handle this one if it's a redundant one. */ | |
4663 | if (TEST_BIT (pre_redundant, INSN_CUID (insn))) | |
4664 | continue; | |
4665 | /* Or if the expression doesn't reach the deleted one. */ | |
4666 | if (! pre_expr_reaches_here_p (avail, expr, | |
4667 | BLOCK_NUM (occr->insn), | |
4668 | NULL)) | |
4669 | continue; | |
4670 | ||
4671 | /* Copy the result of avail to reaching_reg. */ | |
4672 | pre_insert_copy_insn (expr, insn); | |
4673 | avail->copied_p = 1; | |
4674 | } | |
4675 | } | |
4676 | } | |
4677 | } | |
4678 | } | |
4679 | ||
4680 | /* Delete redundant computations. | |
4681 | These are ones that satisy ANTLOC & PPIN. | |
4682 | Deletion is done by changing the insn to copy the `reaching_reg' of | |
4683 | the expression into the result of the SET. It is left to later passes | |
4684 | (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it. | |
4685 | ||
4686 | Returns non-zero if a change is made. */ | |
4687 | ||
4688 | static int | |
4689 | pre_delete () | |
4690 | { | |
4691 | int i, changed; | |
4692 | ||
4693 | changed = 0; | |
4694 | for (i = 0; i < expr_hash_table_size; i++) | |
4695 | { | |
4696 | struct expr *expr; | |
4697 | ||
4698 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
4699 | { | |
4700 | struct occr *occr; | |
4701 | int indx = expr->bitmap_index; | |
4702 | ||
4703 | /* We only need to search antic_occr since we require | |
4704 | ANTLOC != 0. */ | |
4705 | ||
4706 | for (occr = expr->antic_occr; occr != NULL; occr = occr->next) | |
4707 | { | |
4708 | rtx insn = occr->insn; | |
4709 | rtx set; | |
4710 | int bb = BLOCK_NUM (insn); | |
4711 | sbitmap ppin = pre_ppin[bb]; | |
4712 | ||
4713 | if (TEST_BIT (ppin, indx)) | |
4714 | { | |
7506f491 DE |
4715 | set = single_set (insn); |
4716 | if (! set) | |
4717 | abort (); | |
4718 | ||
d3903c22 JL |
4719 | /* Create a pseudo-reg to store the result of reaching |
4720 | expressions into. Get the mode for the new pseudo | |
4721 | from the mode of the original destination pseudo. */ | |
4722 | if (expr->reaching_reg == NULL) | |
4723 | expr->reaching_reg | |
4724 | = gen_reg_rtx (GET_MODE (SET_DEST (set))); | |
4725 | ||
7506f491 DE |
4726 | /* In theory this should never fail since we're creating |
4727 | a reg->reg copy. | |
4728 | ||
4729 | However, on the x86 some of the movXX patterns actually | |
4730 | contain clobbers of scratch regs. This may cause the | |
4731 | insn created by validate_change to not patch any pattern | |
4732 | and thus cause validate_change to fail. */ | |
4733 | if (validate_change (insn, &SET_SRC (set), | |
4734 | expr->reaching_reg, 0)) | |
4735 | { | |
4736 | occr->deleted_p = 1; | |
4737 | SET_BIT (pre_redundant, INSN_CUID (insn)); | |
4738 | changed = 1; | |
4739 | gcse_subst_count++; | |
4740 | } | |
4741 | ||
4742 | if (gcse_file) | |
4743 | { | |
4744 | fprintf (gcse_file, "PRE: redundant insn %d (expression %d) in bb %d, reaching reg is %d\n", | |
4745 | INSN_UID (insn), indx, bb, REGNO (expr->reaching_reg)); | |
4746 | } | |
4747 | } | |
4748 | } | |
4749 | } | |
4750 | } | |
4751 | ||
4752 | return changed; | |
4753 | } | |
4754 | ||
4755 | /* Perform GCSE optimizations using PRE. | |
4756 | This is called by one_pre_gcse_pass after all the dataflow analysis | |
4757 | has been done. | |
4758 | ||
4759 | This is based on the original Morel-Renvoise paper and Fred Chow's thesis. | |
4760 | ||
4761 | The M-R paper uses "TRANSP" to describe an expression as being transparent | |
4762 | in a block where as Chow's thesis uses "ALTERED". We use TRANSP. | |
4763 | ||
4764 | ??? A new pseudo reg is created to hold the reaching expression. | |
4765 | The nice thing about the classical approach is that it would try to | |
4766 | use an existing reg. If the register can't be adequately optimized | |
4767 | [i.e. we introduce reload problems], one could add a pass here to | |
4768 | propagate the new register through the block. | |
4769 | ||
4770 | ??? We don't handle single sets in PARALLELs because we're [currently] | |
4771 | not able to copy the rest of the parallel when we insert copies to create | |
4772 | full redundancies from partial redundancies. However, there's no reason | |
4773 | why we can't handle PARALLELs in the cases where there are no partial | |
4774 | redundancies. */ | |
4775 | ||
4776 | static int | |
4777 | pre_gcse () | |
4778 | { | |
4779 | int i; | |
4780 | int changed; | |
4781 | struct expr **index_map; | |
4782 | ||
4783 | /* Compute a mapping from expression number (`bitmap_index') to | |
4784 | hash table entry. */ | |
4785 | ||
4786 | index_map = (struct expr **) alloca (n_exprs * sizeof (struct expr *)); | |
4787 | bzero ((char *) index_map, n_exprs * sizeof (struct expr *)); | |
4788 | for (i = 0; i < expr_hash_table_size; i++) | |
4789 | { | |
4790 | struct expr *expr; | |
4791 | ||
4792 | for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash) | |
4793 | index_map[expr->bitmap_index] = expr; | |
4794 | } | |
4795 | ||
4796 | /* Reset bitmap used to track which insns are redundant. */ | |
4797 | pre_redundant = sbitmap_alloc (max_cuid); | |
4798 | sbitmap_zero (pre_redundant); | |
4799 | ||
4800 | /* Delete the redundant insns first so that | |
4801 | - we know what register to use for the new insns and for the other | |
4802 | ones with reaching expressions | |
4803 | - we know which insns are redundant when we go to create copies */ | |
4804 | changed = pre_delete (); | |
4805 | ||
4806 | /* Insert insns in places that make partially redundant expressions | |
4807 | fully redundant. */ | |
4808 | pre_insert (index_map); | |
4809 | ||
4810 | /* In other places with reaching expressions, copy the expression to the | |
4811 | specially allocated pseudo-reg that reaches the redundant expression. */ | |
4812 | pre_insert_copies (); | |
4813 | ||
4814 | free (pre_redundant); | |
4815 | ||
4816 | return changed; | |
4817 | } | |
4818 | ||
4819 | /* Top level routine to perform one PRE GCSE pass. | |
4820 | ||
4821 | Return non-zero if a change was made. */ | |
4822 | ||
4823 | static int | |
4824 | one_pre_gcse_pass (f, pass) | |
4825 | rtx f; | |
4826 | int pass; | |
4827 | { | |
4828 | int changed = 0; | |
4829 | ||
4830 | gcse_subst_count = 0; | |
4831 | gcse_create_count = 0; | |
4832 | ||
4833 | alloc_expr_hash_table (max_cuid); | |
4834 | compute_expr_hash_table (f); | |
4835 | if (gcse_file) | |
4836 | dump_hash_table (gcse_file, "Expression", expr_hash_table, | |
4837 | expr_hash_table_size, n_exprs); | |
4838 | if (n_exprs > 0) | |
4839 | { | |
4840 | alloc_pre_mem (n_basic_blocks, n_exprs); | |
4841 | compute_pre_data (); | |
4842 | changed |= pre_gcse (); | |
4843 | free_pre_mem (); | |
4844 | } | |
4845 | free_expr_hash_table (); | |
4846 | ||
4847 | if (gcse_file) | |
4848 | { | |
4849 | fprintf (gcse_file, "\n"); | |
4850 | fprintf (gcse_file, "PRE GCSE of %s, pass %d: %d bytes needed, %d substs, %d insns created\n", | |
4851 | current_function_name, pass, | |
4852 | bytes_used, gcse_subst_count, gcse_create_count); | |
4853 | } | |
4854 | ||
4855 | return changed; | |
4856 | } | |
aeb2f500 JW |
4857 | \f |
4858 | /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN. | |
4859 | We have to add REG_LABEL notes, because the following loop optimization | |
4860 | pass requires them. */ | |
4861 | ||
4862 | /* ??? This is very similar to the loop.c add_label_notes function. We | |
4863 | could probably share code here. */ | |
4864 | ||
4865 | /* ??? If there was a jump optimization pass after gcse and before loop, | |
4866 | then we would not need to do this here, because jump would add the | |
4867 | necessary REG_LABEL notes. */ | |
4868 | ||
4869 | static void | |
4870 | add_label_notes (x, insn) | |
4871 | rtx x; | |
4872 | rtx insn; | |
4873 | { | |
4874 | enum rtx_code code = GET_CODE (x); | |
4875 | int i, j; | |
4876 | char *fmt; | |
4877 | ||
4878 | if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x)) | |
4879 | { | |
6b3603c2 JL |
4880 | /* This code used to ignore labels that referred to dispatch tables to |
4881 | avoid flow generating (slighly) worse code. | |
4882 | ||
4883 | We no longer ignore such label references (see LABEL_REF handling in | |
4884 | mark_jump_label for additional information). */ | |
4885 | REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, XEXP (x, 0), | |
4886 | REG_NOTES (insn)); | |
aeb2f500 JW |
4887 | return; |
4888 | } | |
4889 | ||
4890 | fmt = GET_RTX_FORMAT (code); | |
4891 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
4892 | { | |
4893 | if (fmt[i] == 'e') | |
4894 | add_label_notes (XEXP (x, i), insn); | |
4895 | else if (fmt[i] == 'E') | |
4896 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
4897 | add_label_notes (XVECEXP (x, i, j), insn); | |
4898 | } | |
4899 | } |