Mercurial > hg > CbC > CbC_gcc
comparison gcc/tree-into-ssa.c @ 0:a06113de4d67
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author | kent <kent@cr.ie.u-ryukyu.ac.jp> |
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date | Fri, 17 Jul 2009 14:47:48 +0900 |
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children | 77e2b8dfacca |
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1 /* Rewrite a program in Normal form into SSA. | |
2 Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008 | |
3 Free Software Foundation, Inc. | |
4 Contributed by Diego Novillo <dnovillo@redhat.com> | |
5 | |
6 This file is part of GCC. | |
7 | |
8 GCC is free software; you can redistribute it and/or modify | |
9 it under the terms of the GNU General Public License as published by | |
10 the Free Software Foundation; either version 3, or (at your option) | |
11 any later version. | |
12 | |
13 GCC is distributed in the hope that it will be useful, | |
14 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 GNU General Public License for more details. | |
17 | |
18 You should have received a copy of the GNU General Public License | |
19 along with GCC; see the file COPYING3. If not see | |
20 <http://www.gnu.org/licenses/>. */ | |
21 | |
22 #include "config.h" | |
23 #include "system.h" | |
24 #include "coretypes.h" | |
25 #include "tm.h" | |
26 #include "tree.h" | |
27 #include "flags.h" | |
28 #include "rtl.h" | |
29 #include "tm_p.h" | |
30 #include "langhooks.h" | |
31 #include "hard-reg-set.h" | |
32 #include "basic-block.h" | |
33 #include "output.h" | |
34 #include "expr.h" | |
35 #include "function.h" | |
36 #include "diagnostic.h" | |
37 #include "bitmap.h" | |
38 #include "tree-flow.h" | |
39 #include "gimple.h" | |
40 #include "tree-inline.h" | |
41 #include "varray.h" | |
42 #include "timevar.h" | |
43 #include "hashtab.h" | |
44 #include "tree-dump.h" | |
45 #include "tree-pass.h" | |
46 #include "cfgloop.h" | |
47 #include "domwalk.h" | |
48 #include "ggc.h" | |
49 #include "params.h" | |
50 #include "vecprim.h" | |
51 | |
52 | |
53 /* This file builds the SSA form for a function as described in: | |
54 R. Cytron, J. Ferrante, B. Rosen, M. Wegman, and K. Zadeck. Efficiently | |
55 Computing Static Single Assignment Form and the Control Dependence | |
56 Graph. ACM Transactions on Programming Languages and Systems, | |
57 13(4):451-490, October 1991. */ | |
58 | |
59 /* Structure to map a variable VAR to the set of blocks that contain | |
60 definitions for VAR. */ | |
61 struct def_blocks_d | |
62 { | |
63 /* The variable. */ | |
64 tree var; | |
65 | |
66 /* Blocks that contain definitions of VAR. Bit I will be set if the | |
67 Ith block contains a definition of VAR. */ | |
68 bitmap def_blocks; | |
69 | |
70 /* Blocks that contain a PHI node for VAR. */ | |
71 bitmap phi_blocks; | |
72 | |
73 /* Blocks where VAR is live-on-entry. Similar semantics as | |
74 DEF_BLOCKS. */ | |
75 bitmap livein_blocks; | |
76 }; | |
77 | |
78 | |
79 /* Each entry in DEF_BLOCKS contains an element of type STRUCT | |
80 DEF_BLOCKS_D, mapping a variable VAR to a bitmap describing all the | |
81 basic blocks where VAR is defined (assigned a new value). It also | |
82 contains a bitmap of all the blocks where VAR is live-on-entry | |
83 (i.e., there is a use of VAR in block B without a preceding | |
84 definition in B). The live-on-entry information is used when | |
85 computing PHI pruning heuristics. */ | |
86 static htab_t def_blocks; | |
87 | |
88 /* Stack of trees used to restore the global currdefs to its original | |
89 state after completing rewriting of a block and its dominator | |
90 children. Its elements have the following properties: | |
91 | |
92 - An SSA_NAME (N) indicates that the current definition of the | |
93 underlying variable should be set to the given SSA_NAME. If the | |
94 symbol associated with the SSA_NAME is not a GIMPLE register, the | |
95 next slot in the stack must be a _DECL node (SYM). In this case, | |
96 the name N in the previous slot is the current reaching | |
97 definition for SYM. | |
98 | |
99 - A _DECL node indicates that the underlying variable has no | |
100 current definition. | |
101 | |
102 - A NULL node at the top entry is used to mark the last slot | |
103 associated with the current block. */ | |
104 static VEC(tree,heap) *block_defs_stack; | |
105 | |
106 | |
107 /* Set of existing SSA names being replaced by update_ssa. */ | |
108 static sbitmap old_ssa_names; | |
109 | |
110 /* Set of new SSA names being added by update_ssa. Note that both | |
111 NEW_SSA_NAMES and OLD_SSA_NAMES are dense bitmaps because most of | |
112 the operations done on them are presence tests. */ | |
113 static sbitmap new_ssa_names; | |
114 | |
115 | |
116 /* Symbols whose SSA form needs to be updated or created for the first | |
117 time. */ | |
118 static bitmap syms_to_rename; | |
119 | |
120 /* Subset of SYMS_TO_RENAME. Contains all the GIMPLE register symbols | |
121 that have been marked for renaming. */ | |
122 static bitmap regs_to_rename; | |
123 | |
124 /* Subset of SYMS_TO_RENAME. Contains all the memory symbols | |
125 that have been marked for renaming. */ | |
126 static bitmap mem_syms_to_rename; | |
127 | |
128 /* Set of SSA names that have been marked to be released after they | |
129 were registered in the replacement table. They will be finally | |
130 released after we finish updating the SSA web. */ | |
131 static bitmap names_to_release; | |
132 | |
133 static VEC(gimple_vec, heap) *phis_to_rewrite; | |
134 | |
135 /* The bitmap of non-NULL elements of PHIS_TO_REWRITE. */ | |
136 static bitmap blocks_with_phis_to_rewrite; | |
137 | |
138 /* Growth factor for NEW_SSA_NAMES and OLD_SSA_NAMES. These sets need | |
139 to grow as the callers to register_new_name_mapping will typically | |
140 create new names on the fly. FIXME. Currently set to 1/3 to avoid | |
141 frequent reallocations but still need to find a reasonable growth | |
142 strategy. */ | |
143 #define NAME_SETS_GROWTH_FACTOR (MAX (3, num_ssa_names / 3)) | |
144 | |
145 /* Tuple used to represent replacement mappings. */ | |
146 struct repl_map_d | |
147 { | |
148 tree name; | |
149 bitmap set; | |
150 }; | |
151 | |
152 | |
153 /* NEW -> OLD_SET replacement table. If we are replacing several | |
154 existing SSA names O_1, O_2, ..., O_j with a new name N_i, | |
155 then REPL_TBL[N_i] = { O_1, O_2, ..., O_j }. */ | |
156 static htab_t repl_tbl; | |
157 | |
158 /* true if register_new_name_mapping needs to initialize the data | |
159 structures needed by update_ssa. */ | |
160 static bool need_to_initialize_update_ssa_p = true; | |
161 | |
162 /* true if update_ssa needs to update virtual operands. */ | |
163 static bool need_to_update_vops_p = false; | |
164 | |
165 /* Statistics kept by update_ssa to use in the virtual mapping | |
166 heuristic. If the number of virtual mappings is beyond certain | |
167 threshold, the updater will switch from using the mappings into | |
168 renaming the virtual symbols from scratch. In some cases, the | |
169 large number of name mappings for virtual names causes significant | |
170 slowdowns in the PHI insertion code. */ | |
171 struct update_ssa_stats_d | |
172 { | |
173 unsigned num_virtual_mappings; | |
174 unsigned num_total_mappings; | |
175 bitmap virtual_symbols; | |
176 unsigned num_virtual_symbols; | |
177 }; | |
178 static struct update_ssa_stats_d update_ssa_stats; | |
179 | |
180 /* Global data to attach to the main dominator walk structure. */ | |
181 struct mark_def_sites_global_data | |
182 { | |
183 /* This bitmap contains the variables which are set before they | |
184 are used in a basic block. */ | |
185 bitmap kills; | |
186 | |
187 /* Bitmap of names to rename. */ | |
188 sbitmap names_to_rename; | |
189 | |
190 /* Set of blocks that mark_def_sites deems interesting for the | |
191 renamer to process. */ | |
192 sbitmap interesting_blocks; | |
193 }; | |
194 | |
195 | |
196 /* Information stored for SSA names. */ | |
197 struct ssa_name_info | |
198 { | |
199 /* The current reaching definition replacing this SSA name. */ | |
200 tree current_def; | |
201 | |
202 /* This field indicates whether or not the variable may need PHI nodes. | |
203 See the enum's definition for more detailed information about the | |
204 states. */ | |
205 ENUM_BITFIELD (need_phi_state) need_phi_state : 2; | |
206 | |
207 /* Age of this record (so that info_for_ssa_name table can be cleared | |
208 quickly); if AGE < CURRENT_INFO_FOR_SSA_NAME_AGE, then the fields | |
209 are assumed to be null. */ | |
210 unsigned age; | |
211 }; | |
212 | |
213 /* The information associated with names. */ | |
214 typedef struct ssa_name_info *ssa_name_info_p; | |
215 DEF_VEC_P (ssa_name_info_p); | |
216 DEF_VEC_ALLOC_P (ssa_name_info_p, heap); | |
217 | |
218 static VEC(ssa_name_info_p, heap) *info_for_ssa_name; | |
219 static unsigned current_info_for_ssa_name_age; | |
220 | |
221 /* The set of blocks affected by update_ssa. */ | |
222 static bitmap blocks_to_update; | |
223 | |
224 /* The main entry point to the SSA renamer (rewrite_blocks) may be | |
225 called several times to do different, but related, tasks. | |
226 Initially, we need it to rename the whole program into SSA form. | |
227 At other times, we may need it to only rename into SSA newly | |
228 exposed symbols. Finally, we can also call it to incrementally fix | |
229 an already built SSA web. */ | |
230 enum rewrite_mode { | |
231 /* Convert the whole function into SSA form. */ | |
232 REWRITE_ALL, | |
233 | |
234 /* Incrementally update the SSA web by replacing existing SSA | |
235 names with new ones. See update_ssa for details. */ | |
236 REWRITE_UPDATE | |
237 }; | |
238 | |
239 | |
240 | |
241 | |
242 /* Prototypes for debugging functions. */ | |
243 extern void dump_tree_ssa (FILE *); | |
244 extern void debug_tree_ssa (void); | |
245 extern void debug_def_blocks (void); | |
246 extern void dump_tree_ssa_stats (FILE *); | |
247 extern void debug_tree_ssa_stats (void); | |
248 extern void dump_update_ssa (FILE *); | |
249 extern void debug_update_ssa (void); | |
250 extern void dump_names_replaced_by (FILE *, tree); | |
251 extern void debug_names_replaced_by (tree); | |
252 extern void dump_def_blocks (FILE *); | |
253 extern void debug_def_blocks (void); | |
254 extern void dump_defs_stack (FILE *, int); | |
255 extern void debug_defs_stack (int); | |
256 extern void dump_currdefs (FILE *); | |
257 extern void debug_currdefs (void); | |
258 | |
259 /* Return true if STMT needs to be rewritten. When renaming a subset | |
260 of the variables, not all statements will be processed. This is | |
261 decided in mark_def_sites. */ | |
262 | |
263 static inline bool | |
264 rewrite_uses_p (gimple stmt) | |
265 { | |
266 return gimple_visited_p (stmt); | |
267 } | |
268 | |
269 | |
270 /* Set the rewrite marker on STMT to the value given by REWRITE_P. */ | |
271 | |
272 static inline void | |
273 set_rewrite_uses (gimple stmt, bool rewrite_p) | |
274 { | |
275 gimple_set_visited (stmt, rewrite_p); | |
276 } | |
277 | |
278 | |
279 /* Return true if the DEFs created by statement STMT should be | |
280 registered when marking new definition sites. This is slightly | |
281 different than rewrite_uses_p: it's used by update_ssa to | |
282 distinguish statements that need to have both uses and defs | |
283 processed from those that only need to have their defs processed. | |
284 Statements that define new SSA names only need to have their defs | |
285 registered, but they don't need to have their uses renamed. */ | |
286 | |
287 static inline bool | |
288 register_defs_p (gimple stmt) | |
289 { | |
290 return gimple_plf (stmt, GF_PLF_1) != 0; | |
291 } | |
292 | |
293 | |
294 /* If REGISTER_DEFS_P is true, mark STMT to have its DEFs registered. */ | |
295 | |
296 static inline void | |
297 set_register_defs (gimple stmt, bool register_defs_p) | |
298 { | |
299 gimple_set_plf (stmt, GF_PLF_1, register_defs_p); | |
300 } | |
301 | |
302 | |
303 /* Get the information associated with NAME. */ | |
304 | |
305 static inline ssa_name_info_p | |
306 get_ssa_name_ann (tree name) | |
307 { | |
308 unsigned ver = SSA_NAME_VERSION (name); | |
309 unsigned len = VEC_length (ssa_name_info_p, info_for_ssa_name); | |
310 struct ssa_name_info *info; | |
311 | |
312 if (ver >= len) | |
313 { | |
314 unsigned new_len = num_ssa_names; | |
315 | |
316 VEC_reserve (ssa_name_info_p, heap, info_for_ssa_name, new_len); | |
317 while (len++ < new_len) | |
318 { | |
319 struct ssa_name_info *info = XCNEW (struct ssa_name_info); | |
320 info->age = current_info_for_ssa_name_age; | |
321 VEC_quick_push (ssa_name_info_p, info_for_ssa_name, info); | |
322 } | |
323 } | |
324 | |
325 info = VEC_index (ssa_name_info_p, info_for_ssa_name, ver); | |
326 if (info->age < current_info_for_ssa_name_age) | |
327 { | |
328 info->need_phi_state = 0; | |
329 info->current_def = NULL_TREE; | |
330 info->age = current_info_for_ssa_name_age; | |
331 } | |
332 | |
333 return info; | |
334 } | |
335 | |
336 | |
337 /* Clears info for SSA names. */ | |
338 | |
339 static void | |
340 clear_ssa_name_info (void) | |
341 { | |
342 current_info_for_ssa_name_age++; | |
343 } | |
344 | |
345 | |
346 /* Get phi_state field for VAR. */ | |
347 | |
348 static inline enum need_phi_state | |
349 get_phi_state (tree var) | |
350 { | |
351 if (TREE_CODE (var) == SSA_NAME) | |
352 return get_ssa_name_ann (var)->need_phi_state; | |
353 else | |
354 return var_ann (var)->need_phi_state; | |
355 } | |
356 | |
357 | |
358 /* Sets phi_state field for VAR to STATE. */ | |
359 | |
360 static inline void | |
361 set_phi_state (tree var, enum need_phi_state state) | |
362 { | |
363 if (TREE_CODE (var) == SSA_NAME) | |
364 get_ssa_name_ann (var)->need_phi_state = state; | |
365 else | |
366 var_ann (var)->need_phi_state = state; | |
367 } | |
368 | |
369 | |
370 /* Return the current definition for VAR. */ | |
371 | |
372 tree | |
373 get_current_def (tree var) | |
374 { | |
375 if (TREE_CODE (var) == SSA_NAME) | |
376 return get_ssa_name_ann (var)->current_def; | |
377 else | |
378 return var_ann (var)->current_def; | |
379 } | |
380 | |
381 | |
382 /* Sets current definition of VAR to DEF. */ | |
383 | |
384 void | |
385 set_current_def (tree var, tree def) | |
386 { | |
387 if (TREE_CODE (var) == SSA_NAME) | |
388 get_ssa_name_ann (var)->current_def = def; | |
389 else | |
390 var_ann (var)->current_def = def; | |
391 } | |
392 | |
393 | |
394 /* Compute global livein information given the set of blocks where | |
395 an object is locally live at the start of the block (LIVEIN) | |
396 and the set of blocks where the object is defined (DEF_BLOCKS). | |
397 | |
398 Note: This routine augments the existing local livein information | |
399 to include global livein (i.e., it modifies the underlying bitmap | |
400 for LIVEIN). */ | |
401 | |
402 void | |
403 compute_global_livein (bitmap livein ATTRIBUTE_UNUSED, bitmap def_blocks ATTRIBUTE_UNUSED) | |
404 { | |
405 basic_block bb, *worklist, *tos; | |
406 unsigned i; | |
407 bitmap_iterator bi; | |
408 | |
409 tos = worklist | |
410 = (basic_block *) xmalloc (sizeof (basic_block) * (last_basic_block + 1)); | |
411 | |
412 EXECUTE_IF_SET_IN_BITMAP (livein, 0, i, bi) | |
413 *tos++ = BASIC_BLOCK (i); | |
414 | |
415 /* Iterate until the worklist is empty. */ | |
416 while (tos != worklist) | |
417 { | |
418 edge e; | |
419 edge_iterator ei; | |
420 | |
421 /* Pull a block off the worklist. */ | |
422 bb = *--tos; | |
423 | |
424 /* For each predecessor block. */ | |
425 FOR_EACH_EDGE (e, ei, bb->preds) | |
426 { | |
427 basic_block pred = e->src; | |
428 int pred_index = pred->index; | |
429 | |
430 /* None of this is necessary for the entry block. */ | |
431 if (pred != ENTRY_BLOCK_PTR | |
432 && ! bitmap_bit_p (livein, pred_index) | |
433 && ! bitmap_bit_p (def_blocks, pred_index)) | |
434 { | |
435 *tos++ = pred; | |
436 bitmap_set_bit (livein, pred_index); | |
437 } | |
438 } | |
439 } | |
440 | |
441 free (worklist); | |
442 } | |
443 | |
444 | |
445 /* Cleans up the REWRITE_THIS_STMT and REGISTER_DEFS_IN_THIS_STMT flags for | |
446 all statements in basic block BB. */ | |
447 | |
448 static void | |
449 initialize_flags_in_bb (basic_block bb) | |
450 { | |
451 gimple stmt; | |
452 gimple_stmt_iterator gsi; | |
453 | |
454 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
455 { | |
456 gimple phi = gsi_stmt (gsi); | |
457 set_rewrite_uses (phi, false); | |
458 set_register_defs (phi, false); | |
459 } | |
460 | |
461 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
462 { | |
463 stmt = gsi_stmt (gsi); | |
464 | |
465 /* We are going to use the operand cache API, such as | |
466 SET_USE, SET_DEF, and FOR_EACH_IMM_USE_FAST. The operand | |
467 cache for each statement should be up-to-date. */ | |
468 gcc_assert (!gimple_modified_p (stmt)); | |
469 set_rewrite_uses (stmt, false); | |
470 set_register_defs (stmt, false); | |
471 } | |
472 } | |
473 | |
474 /* Mark block BB as interesting for update_ssa. */ | |
475 | |
476 static void | |
477 mark_block_for_update (basic_block bb) | |
478 { | |
479 gcc_assert (blocks_to_update != NULL); | |
480 if (bitmap_bit_p (blocks_to_update, bb->index)) | |
481 return; | |
482 bitmap_set_bit (blocks_to_update, bb->index); | |
483 initialize_flags_in_bb (bb); | |
484 } | |
485 | |
486 /* Return the set of blocks where variable VAR is defined and the blocks | |
487 where VAR is live on entry (livein). If no entry is found in | |
488 DEF_BLOCKS, a new one is created and returned. */ | |
489 | |
490 static inline struct def_blocks_d * | |
491 get_def_blocks_for (tree var) | |
492 { | |
493 struct def_blocks_d db, *db_p; | |
494 void **slot; | |
495 | |
496 db.var = var; | |
497 slot = htab_find_slot (def_blocks, (void *) &db, INSERT); | |
498 if (*slot == NULL) | |
499 { | |
500 db_p = XNEW (struct def_blocks_d); | |
501 db_p->var = var; | |
502 db_p->def_blocks = BITMAP_ALLOC (NULL); | |
503 db_p->phi_blocks = BITMAP_ALLOC (NULL); | |
504 db_p->livein_blocks = BITMAP_ALLOC (NULL); | |
505 *slot = (void *) db_p; | |
506 } | |
507 else | |
508 db_p = (struct def_blocks_d *) *slot; | |
509 | |
510 return db_p; | |
511 } | |
512 | |
513 | |
514 /* Mark block BB as the definition site for variable VAR. PHI_P is true if | |
515 VAR is defined by a PHI node. */ | |
516 | |
517 static void | |
518 set_def_block (tree var, basic_block bb, bool phi_p) | |
519 { | |
520 struct def_blocks_d *db_p; | |
521 enum need_phi_state state; | |
522 | |
523 state = get_phi_state (var); | |
524 db_p = get_def_blocks_for (var); | |
525 | |
526 /* Set the bit corresponding to the block where VAR is defined. */ | |
527 bitmap_set_bit (db_p->def_blocks, bb->index); | |
528 if (phi_p) | |
529 bitmap_set_bit (db_p->phi_blocks, bb->index); | |
530 | |
531 /* Keep track of whether or not we may need to insert PHI nodes. | |
532 | |
533 If we are in the UNKNOWN state, then this is the first definition | |
534 of VAR. Additionally, we have not seen any uses of VAR yet, so | |
535 we do not need a PHI node for this variable at this time (i.e., | |
536 transition to NEED_PHI_STATE_NO). | |
537 | |
538 If we are in any other state, then we either have multiple definitions | |
539 of this variable occurring in different blocks or we saw a use of the | |
540 variable which was not dominated by the block containing the | |
541 definition(s). In this case we may need a PHI node, so enter | |
542 state NEED_PHI_STATE_MAYBE. */ | |
543 if (state == NEED_PHI_STATE_UNKNOWN) | |
544 set_phi_state (var, NEED_PHI_STATE_NO); | |
545 else | |
546 set_phi_state (var, NEED_PHI_STATE_MAYBE); | |
547 } | |
548 | |
549 | |
550 /* Mark block BB as having VAR live at the entry to BB. */ | |
551 | |
552 static void | |
553 set_livein_block (tree var, basic_block bb) | |
554 { | |
555 struct def_blocks_d *db_p; | |
556 enum need_phi_state state = get_phi_state (var); | |
557 | |
558 db_p = get_def_blocks_for (var); | |
559 | |
560 /* Set the bit corresponding to the block where VAR is live in. */ | |
561 bitmap_set_bit (db_p->livein_blocks, bb->index); | |
562 | |
563 /* Keep track of whether or not we may need to insert PHI nodes. | |
564 | |
565 If we reach here in NEED_PHI_STATE_NO, see if this use is dominated | |
566 by the single block containing the definition(s) of this variable. If | |
567 it is, then we remain in NEED_PHI_STATE_NO, otherwise we transition to | |
568 NEED_PHI_STATE_MAYBE. */ | |
569 if (state == NEED_PHI_STATE_NO) | |
570 { | |
571 int def_block_index = bitmap_first_set_bit (db_p->def_blocks); | |
572 | |
573 if (def_block_index == -1 | |
574 || ! dominated_by_p (CDI_DOMINATORS, bb, | |
575 BASIC_BLOCK (def_block_index))) | |
576 set_phi_state (var, NEED_PHI_STATE_MAYBE); | |
577 } | |
578 else | |
579 set_phi_state (var, NEED_PHI_STATE_MAYBE); | |
580 } | |
581 | |
582 | |
583 /* Return true if symbol SYM is marked for renaming. */ | |
584 | |
585 static inline bool | |
586 symbol_marked_for_renaming (tree sym) | |
587 { | |
588 return bitmap_bit_p (syms_to_rename, DECL_UID (sym)); | |
589 } | |
590 | |
591 | |
592 /* Return true if NAME is in OLD_SSA_NAMES. */ | |
593 | |
594 static inline bool | |
595 is_old_name (tree name) | |
596 { | |
597 unsigned ver = SSA_NAME_VERSION (name); | |
598 return ver < new_ssa_names->n_bits && TEST_BIT (old_ssa_names, ver); | |
599 } | |
600 | |
601 | |
602 /* Return true if NAME is in NEW_SSA_NAMES. */ | |
603 | |
604 static inline bool | |
605 is_new_name (tree name) | |
606 { | |
607 unsigned ver = SSA_NAME_VERSION (name); | |
608 return ver < new_ssa_names->n_bits && TEST_BIT (new_ssa_names, ver); | |
609 } | |
610 | |
611 | |
612 /* Hashing and equality functions for REPL_TBL. */ | |
613 | |
614 static hashval_t | |
615 repl_map_hash (const void *p) | |
616 { | |
617 return htab_hash_pointer ((const void *)((const struct repl_map_d *)p)->name); | |
618 } | |
619 | |
620 static int | |
621 repl_map_eq (const void *p1, const void *p2) | |
622 { | |
623 return ((const struct repl_map_d *)p1)->name | |
624 == ((const struct repl_map_d *)p2)->name; | |
625 } | |
626 | |
627 static void | |
628 repl_map_free (void *p) | |
629 { | |
630 BITMAP_FREE (((struct repl_map_d *)p)->set); | |
631 free (p); | |
632 } | |
633 | |
634 | |
635 /* Return the names replaced by NEW_TREE (i.e., REPL_TBL[NEW_TREE].SET). */ | |
636 | |
637 static inline bitmap | |
638 names_replaced_by (tree new_tree) | |
639 { | |
640 struct repl_map_d m; | |
641 void **slot; | |
642 | |
643 m.name = new_tree; | |
644 slot = htab_find_slot (repl_tbl, (void *) &m, NO_INSERT); | |
645 | |
646 /* If N was not registered in the replacement table, return NULL. */ | |
647 if (slot == NULL || *slot == NULL) | |
648 return NULL; | |
649 | |
650 return ((struct repl_map_d *) *slot)->set; | |
651 } | |
652 | |
653 | |
654 /* Add OLD to REPL_TBL[NEW_TREE].SET. */ | |
655 | |
656 static inline void | |
657 add_to_repl_tbl (tree new_tree, tree old) | |
658 { | |
659 struct repl_map_d m, *mp; | |
660 void **slot; | |
661 | |
662 m.name = new_tree; | |
663 slot = htab_find_slot (repl_tbl, (void *) &m, INSERT); | |
664 if (*slot == NULL) | |
665 { | |
666 mp = XNEW (struct repl_map_d); | |
667 mp->name = new_tree; | |
668 mp->set = BITMAP_ALLOC (NULL); | |
669 *slot = (void *) mp; | |
670 } | |
671 else | |
672 mp = (struct repl_map_d *) *slot; | |
673 | |
674 bitmap_set_bit (mp->set, SSA_NAME_VERSION (old)); | |
675 } | |
676 | |
677 | |
678 /* Add a new mapping NEW_TREE -> OLD REPL_TBL. Every entry N_i in REPL_TBL | |
679 represents the set of names O_1 ... O_j replaced by N_i. This is | |
680 used by update_ssa and its helpers to introduce new SSA names in an | |
681 already formed SSA web. */ | |
682 | |
683 static void | |
684 add_new_name_mapping (tree new_tree, tree old) | |
685 { | |
686 timevar_push (TV_TREE_SSA_INCREMENTAL); | |
687 | |
688 /* OLD and NEW_TREE must be different SSA names for the same symbol. */ | |
689 gcc_assert (new_tree != old && SSA_NAME_VAR (new_tree) == SSA_NAME_VAR (old)); | |
690 | |
691 /* If this mapping is for virtual names, we will need to update | |
692 virtual operands. If this is a mapping for .MEM, then we gather | |
693 the symbols associated with each name. */ | |
694 if (!is_gimple_reg (new_tree)) | |
695 { | |
696 tree sym; | |
697 | |
698 need_to_update_vops_p = true; | |
699 | |
700 update_ssa_stats.num_virtual_mappings++; | |
701 update_ssa_stats.num_virtual_symbols++; | |
702 | |
703 /* Keep counts of virtual mappings and symbols to use in the | |
704 virtual mapping heuristic. If we have large numbers of | |
705 virtual mappings for a relatively low number of symbols, it | |
706 will make more sense to rename the symbols from scratch. | |
707 Otherwise, the insertion of PHI nodes for each of the old | |
708 names in these mappings will be very slow. */ | |
709 sym = SSA_NAME_VAR (new_tree); | |
710 bitmap_set_bit (update_ssa_stats.virtual_symbols, DECL_UID (sym)); | |
711 } | |
712 | |
713 /* We may need to grow NEW_SSA_NAMES and OLD_SSA_NAMES because our | |
714 caller may have created new names since the set was created. */ | |
715 if (new_ssa_names->n_bits <= num_ssa_names - 1) | |
716 { | |
717 unsigned int new_sz = num_ssa_names + NAME_SETS_GROWTH_FACTOR; | |
718 new_ssa_names = sbitmap_resize (new_ssa_names, new_sz, 0); | |
719 old_ssa_names = sbitmap_resize (old_ssa_names, new_sz, 0); | |
720 } | |
721 | |
722 /* Update the REPL_TBL table. */ | |
723 add_to_repl_tbl (new_tree, old); | |
724 | |
725 /* If OLD had already been registered as a new name, then all the | |
726 names that OLD replaces should also be replaced by NEW_TREE. */ | |
727 if (is_new_name (old)) | |
728 bitmap_ior_into (names_replaced_by (new_tree), names_replaced_by (old)); | |
729 | |
730 /* Register NEW_TREE and OLD in NEW_SSA_NAMES and OLD_SSA_NAMES, | |
731 respectively. */ | |
732 SET_BIT (new_ssa_names, SSA_NAME_VERSION (new_tree)); | |
733 SET_BIT (old_ssa_names, SSA_NAME_VERSION (old)); | |
734 | |
735 /* Update mapping counter to use in the virtual mapping heuristic. */ | |
736 update_ssa_stats.num_total_mappings++; | |
737 | |
738 timevar_pop (TV_TREE_SSA_INCREMENTAL); | |
739 } | |
740 | |
741 | |
742 /* Call back for walk_dominator_tree used to collect definition sites | |
743 for every variable in the function. For every statement S in block | |
744 BB: | |
745 | |
746 1- Variables defined by S in the DEFS of S are marked in the bitmap | |
747 WALK_DATA->GLOBAL_DATA->KILLS. | |
748 | |
749 2- If S uses a variable VAR and there is no preceding kill of VAR, | |
750 then it is marked in the LIVEIN_BLOCKS bitmap associated with VAR. | |
751 | |
752 This information is used to determine which variables are live | |
753 across block boundaries to reduce the number of PHI nodes | |
754 we create. */ | |
755 | |
756 static void | |
757 mark_def_sites (struct dom_walk_data *walk_data, basic_block bb, | |
758 gimple_stmt_iterator gsi) | |
759 { | |
760 struct mark_def_sites_global_data *gd; | |
761 bitmap kills; | |
762 tree def; | |
763 gimple stmt; | |
764 use_operand_p use_p; | |
765 ssa_op_iter iter; | |
766 | |
767 /* Since this is the first time that we rewrite the program into SSA | |
768 form, force an operand scan on every statement. */ | |
769 stmt = gsi_stmt (gsi); | |
770 update_stmt (stmt); | |
771 | |
772 gd = (struct mark_def_sites_global_data *) walk_data->global_data; | |
773 kills = gd->kills; | |
774 | |
775 gcc_assert (blocks_to_update == NULL); | |
776 set_register_defs (stmt, false); | |
777 set_rewrite_uses (stmt, false); | |
778 | |
779 /* If a variable is used before being set, then the variable is live | |
780 across a block boundary, so mark it live-on-entry to BB. */ | |
781 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE) | |
782 { | |
783 tree sym = USE_FROM_PTR (use_p); | |
784 gcc_assert (DECL_P (sym)); | |
785 if (!bitmap_bit_p (kills, DECL_UID (sym))) | |
786 set_livein_block (sym, bb); | |
787 set_rewrite_uses (stmt, true); | |
788 } | |
789 | |
790 /* Now process the defs. Mark BB as the definition block and add | |
791 each def to the set of killed symbols. */ | |
792 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) | |
793 { | |
794 gcc_assert (DECL_P (def)); | |
795 set_def_block (def, bb, false); | |
796 bitmap_set_bit (kills, DECL_UID (def)); | |
797 set_register_defs (stmt, true); | |
798 } | |
799 | |
800 /* If we found the statement interesting then also mark the block BB | |
801 as interesting. */ | |
802 if (rewrite_uses_p (stmt) || register_defs_p (stmt)) | |
803 SET_BIT (gd->interesting_blocks, bb->index); | |
804 } | |
805 | |
806 /* Structure used by prune_unused_phi_nodes to record bounds of the intervals | |
807 in the dfs numbering of the dominance tree. */ | |
808 | |
809 struct dom_dfsnum | |
810 { | |
811 /* Basic block whose index this entry corresponds to. */ | |
812 unsigned bb_index; | |
813 | |
814 /* The dfs number of this node. */ | |
815 unsigned dfs_num; | |
816 }; | |
817 | |
818 /* Compares two entries of type struct dom_dfsnum by dfs_num field. Callback | |
819 for qsort. */ | |
820 | |
821 static int | |
822 cmp_dfsnum (const void *a, const void *b) | |
823 { | |
824 const struct dom_dfsnum *const da = (const struct dom_dfsnum *) a; | |
825 const struct dom_dfsnum *const db = (const struct dom_dfsnum *) b; | |
826 | |
827 return (int) da->dfs_num - (int) db->dfs_num; | |
828 } | |
829 | |
830 /* Among the intervals starting at the N points specified in DEFS, find | |
831 the one that contains S, and return its bb_index. */ | |
832 | |
833 static unsigned | |
834 find_dfsnum_interval (struct dom_dfsnum *defs, unsigned n, unsigned s) | |
835 { | |
836 unsigned f = 0, t = n, m; | |
837 | |
838 while (t > f + 1) | |
839 { | |
840 m = (f + t) / 2; | |
841 if (defs[m].dfs_num <= s) | |
842 f = m; | |
843 else | |
844 t = m; | |
845 } | |
846 | |
847 return defs[f].bb_index; | |
848 } | |
849 | |
850 /* Clean bits from PHIS for phi nodes whose value cannot be used in USES. | |
851 KILLS is a bitmap of blocks where the value is defined before any use. */ | |
852 | |
853 static void | |
854 prune_unused_phi_nodes (bitmap phis, bitmap kills, bitmap uses) | |
855 { | |
856 VEC(int, heap) *worklist; | |
857 bitmap_iterator bi; | |
858 unsigned i, b, p, u, top; | |
859 bitmap live_phis; | |
860 basic_block def_bb, use_bb; | |
861 edge e; | |
862 edge_iterator ei; | |
863 bitmap to_remove; | |
864 struct dom_dfsnum *defs; | |
865 unsigned n_defs, adef; | |
866 | |
867 if (bitmap_empty_p (uses)) | |
868 { | |
869 bitmap_clear (phis); | |
870 return; | |
871 } | |
872 | |
873 /* The phi must dominate a use, or an argument of a live phi. Also, we | |
874 do not create any phi nodes in def blocks, unless they are also livein. */ | |
875 to_remove = BITMAP_ALLOC (NULL); | |
876 bitmap_and_compl (to_remove, kills, uses); | |
877 bitmap_and_compl_into (phis, to_remove); | |
878 if (bitmap_empty_p (phis)) | |
879 { | |
880 BITMAP_FREE (to_remove); | |
881 return; | |
882 } | |
883 | |
884 /* We want to remove the unnecessary phi nodes, but we do not want to compute | |
885 liveness information, as that may be linear in the size of CFG, and if | |
886 there are lot of different variables to rewrite, this may lead to quadratic | |
887 behavior. | |
888 | |
889 Instead, we basically emulate standard dce. We put all uses to worklist, | |
890 then for each of them find the nearest def that dominates them. If this | |
891 def is a phi node, we mark it live, and if it was not live before, we | |
892 add the predecessors of its basic block to the worklist. | |
893 | |
894 To quickly locate the nearest def that dominates use, we use dfs numbering | |
895 of the dominance tree (that is already available in order to speed up | |
896 queries). For each def, we have the interval given by the dfs number on | |
897 entry to and on exit from the corresponding subtree in the dominance tree. | |
898 The nearest dominator for a given use is the smallest of these intervals | |
899 that contains entry and exit dfs numbers for the basic block with the use. | |
900 If we store the bounds for all the uses to an array and sort it, we can | |
901 locate the nearest dominating def in logarithmic time by binary search.*/ | |
902 bitmap_ior (to_remove, kills, phis); | |
903 n_defs = bitmap_count_bits (to_remove); | |
904 defs = XNEWVEC (struct dom_dfsnum, 2 * n_defs + 1); | |
905 defs[0].bb_index = 1; | |
906 defs[0].dfs_num = 0; | |
907 adef = 1; | |
908 EXECUTE_IF_SET_IN_BITMAP (to_remove, 0, i, bi) | |
909 { | |
910 def_bb = BASIC_BLOCK (i); | |
911 defs[adef].bb_index = i; | |
912 defs[adef].dfs_num = bb_dom_dfs_in (CDI_DOMINATORS, def_bb); | |
913 defs[adef + 1].bb_index = i; | |
914 defs[adef + 1].dfs_num = bb_dom_dfs_out (CDI_DOMINATORS, def_bb); | |
915 adef += 2; | |
916 } | |
917 BITMAP_FREE (to_remove); | |
918 gcc_assert (adef == 2 * n_defs + 1); | |
919 qsort (defs, adef, sizeof (struct dom_dfsnum), cmp_dfsnum); | |
920 gcc_assert (defs[0].bb_index == 1); | |
921 | |
922 /* Now each DEFS entry contains the number of the basic block to that the | |
923 dfs number corresponds. Change them to the number of basic block that | |
924 corresponds to the interval following the dfs number. Also, for the | |
925 dfs_out numbers, increase the dfs number by one (so that it corresponds | |
926 to the start of the following interval, not to the end of the current | |
927 one). We use WORKLIST as a stack. */ | |
928 worklist = VEC_alloc (int, heap, n_defs + 1); | |
929 VEC_quick_push (int, worklist, 1); | |
930 top = 1; | |
931 n_defs = 1; | |
932 for (i = 1; i < adef; i++) | |
933 { | |
934 b = defs[i].bb_index; | |
935 if (b == top) | |
936 { | |
937 /* This is a closing element. Interval corresponding to the top | |
938 of the stack after removing it follows. */ | |
939 VEC_pop (int, worklist); | |
940 top = VEC_index (int, worklist, VEC_length (int, worklist) - 1); | |
941 defs[n_defs].bb_index = top; | |
942 defs[n_defs].dfs_num = defs[i].dfs_num + 1; | |
943 } | |
944 else | |
945 { | |
946 /* Opening element. Nothing to do, just push it to the stack and move | |
947 it to the correct position. */ | |
948 defs[n_defs].bb_index = defs[i].bb_index; | |
949 defs[n_defs].dfs_num = defs[i].dfs_num; | |
950 VEC_quick_push (int, worklist, b); | |
951 top = b; | |
952 } | |
953 | |
954 /* If this interval starts at the same point as the previous one, cancel | |
955 the previous one. */ | |
956 if (defs[n_defs].dfs_num == defs[n_defs - 1].dfs_num) | |
957 defs[n_defs - 1].bb_index = defs[n_defs].bb_index; | |
958 else | |
959 n_defs++; | |
960 } | |
961 VEC_pop (int, worklist); | |
962 gcc_assert (VEC_empty (int, worklist)); | |
963 | |
964 /* Now process the uses. */ | |
965 live_phis = BITMAP_ALLOC (NULL); | |
966 EXECUTE_IF_SET_IN_BITMAP (uses, 0, i, bi) | |
967 { | |
968 VEC_safe_push (int, heap, worklist, i); | |
969 } | |
970 | |
971 while (!VEC_empty (int, worklist)) | |
972 { | |
973 b = VEC_pop (int, worklist); | |
974 if (b == ENTRY_BLOCK) | |
975 continue; | |
976 | |
977 /* If there is a phi node in USE_BB, it is made live. Otherwise, | |
978 find the def that dominates the immediate dominator of USE_BB | |
979 (the kill in USE_BB does not dominate the use). */ | |
980 if (bitmap_bit_p (phis, b)) | |
981 p = b; | |
982 else | |
983 { | |
984 use_bb = get_immediate_dominator (CDI_DOMINATORS, BASIC_BLOCK (b)); | |
985 p = find_dfsnum_interval (defs, n_defs, | |
986 bb_dom_dfs_in (CDI_DOMINATORS, use_bb)); | |
987 if (!bitmap_bit_p (phis, p)) | |
988 continue; | |
989 } | |
990 | |
991 /* If the phi node is already live, there is nothing to do. */ | |
992 if (bitmap_bit_p (live_phis, p)) | |
993 continue; | |
994 | |
995 /* Mark the phi as live, and add the new uses to the worklist. */ | |
996 bitmap_set_bit (live_phis, p); | |
997 def_bb = BASIC_BLOCK (p); | |
998 FOR_EACH_EDGE (e, ei, def_bb->preds) | |
999 { | |
1000 u = e->src->index; | |
1001 if (bitmap_bit_p (uses, u)) | |
1002 continue; | |
1003 | |
1004 /* In case there is a kill directly in the use block, do not record | |
1005 the use (this is also necessary for correctness, as we assume that | |
1006 uses dominated by a def directly in their block have been filtered | |
1007 out before). */ | |
1008 if (bitmap_bit_p (kills, u)) | |
1009 continue; | |
1010 | |
1011 bitmap_set_bit (uses, u); | |
1012 VEC_safe_push (int, heap, worklist, u); | |
1013 } | |
1014 } | |
1015 | |
1016 VEC_free (int, heap, worklist); | |
1017 bitmap_copy (phis, live_phis); | |
1018 BITMAP_FREE (live_phis); | |
1019 free (defs); | |
1020 } | |
1021 | |
1022 /* Return the set of blocks where variable VAR is defined and the blocks | |
1023 where VAR is live on entry (livein). Return NULL, if no entry is | |
1024 found in DEF_BLOCKS. */ | |
1025 | |
1026 static inline struct def_blocks_d * | |
1027 find_def_blocks_for (tree var) | |
1028 { | |
1029 struct def_blocks_d dm; | |
1030 dm.var = var; | |
1031 return (struct def_blocks_d *) htab_find (def_blocks, &dm); | |
1032 } | |
1033 | |
1034 | |
1035 /* Retrieve or create a default definition for symbol SYM. */ | |
1036 | |
1037 static inline tree | |
1038 get_default_def_for (tree sym) | |
1039 { | |
1040 tree ddef = gimple_default_def (cfun, sym); | |
1041 | |
1042 if (ddef == NULL_TREE) | |
1043 { | |
1044 ddef = make_ssa_name (sym, gimple_build_nop ()); | |
1045 set_default_def (sym, ddef); | |
1046 } | |
1047 | |
1048 return ddef; | |
1049 } | |
1050 | |
1051 | |
1052 /* Marks phi node PHI in basic block BB for rewrite. */ | |
1053 | |
1054 static void | |
1055 mark_phi_for_rewrite (basic_block bb, gimple phi) | |
1056 { | |
1057 gimple_vec phis; | |
1058 unsigned i, idx = bb->index; | |
1059 | |
1060 if (rewrite_uses_p (phi)) | |
1061 return; | |
1062 | |
1063 set_rewrite_uses (phi, true); | |
1064 | |
1065 if (!blocks_with_phis_to_rewrite) | |
1066 return; | |
1067 | |
1068 bitmap_set_bit (blocks_with_phis_to_rewrite, idx); | |
1069 VEC_reserve (gimple_vec, heap, phis_to_rewrite, last_basic_block + 1); | |
1070 for (i = VEC_length (gimple_vec, phis_to_rewrite); i <= idx; i++) | |
1071 VEC_quick_push (gimple_vec, phis_to_rewrite, NULL); | |
1072 | |
1073 phis = VEC_index (gimple_vec, phis_to_rewrite, idx); | |
1074 if (!phis) | |
1075 phis = VEC_alloc (gimple, heap, 10); | |
1076 | |
1077 VEC_safe_push (gimple, heap, phis, phi); | |
1078 VEC_replace (gimple_vec, phis_to_rewrite, idx, phis); | |
1079 } | |
1080 | |
1081 | |
1082 /* Insert PHI nodes for variable VAR using the iterated dominance | |
1083 frontier given in PHI_INSERTION_POINTS. If UPDATE_P is true, this | |
1084 function assumes that the caller is incrementally updating the | |
1085 existing SSA form, in which case VAR may be an SSA name instead of | |
1086 a symbol. | |
1087 | |
1088 PHI_INSERTION_POINTS is updated to reflect nodes that already had a | |
1089 PHI node for VAR. On exit, only the nodes that received a PHI node | |
1090 for VAR will be present in PHI_INSERTION_POINTS. */ | |
1091 | |
1092 static void | |
1093 insert_phi_nodes_for (tree var, bitmap phi_insertion_points, bool update_p) | |
1094 { | |
1095 unsigned bb_index; | |
1096 edge e; | |
1097 gimple phi; | |
1098 basic_block bb; | |
1099 bitmap_iterator bi; | |
1100 struct def_blocks_d *def_map; | |
1101 | |
1102 def_map = find_def_blocks_for (var); | |
1103 gcc_assert (def_map); | |
1104 | |
1105 /* Remove the blocks where we already have PHI nodes for VAR. */ | |
1106 bitmap_and_compl_into (phi_insertion_points, def_map->phi_blocks); | |
1107 | |
1108 /* Remove obviously useless phi nodes. */ | |
1109 prune_unused_phi_nodes (phi_insertion_points, def_map->def_blocks, | |
1110 def_map->livein_blocks); | |
1111 | |
1112 /* And insert the PHI nodes. */ | |
1113 EXECUTE_IF_SET_IN_BITMAP (phi_insertion_points, 0, bb_index, bi) | |
1114 { | |
1115 bb = BASIC_BLOCK (bb_index); | |
1116 if (update_p) | |
1117 mark_block_for_update (bb); | |
1118 | |
1119 phi = NULL; | |
1120 | |
1121 if (TREE_CODE (var) == SSA_NAME) | |
1122 { | |
1123 /* If we are rewriting SSA names, create the LHS of the PHI | |
1124 node by duplicating VAR. This is useful in the case of | |
1125 pointers, to also duplicate pointer attributes (alias | |
1126 information, in particular). */ | |
1127 edge_iterator ei; | |
1128 tree new_lhs; | |
1129 | |
1130 gcc_assert (update_p); | |
1131 phi = create_phi_node (var, bb); | |
1132 | |
1133 new_lhs = duplicate_ssa_name (var, phi); | |
1134 gimple_phi_set_result (phi, new_lhs); | |
1135 add_new_name_mapping (new_lhs, var); | |
1136 | |
1137 /* Add VAR to every argument slot of PHI. We need VAR in | |
1138 every argument so that rewrite_update_phi_arguments knows | |
1139 which name is this PHI node replacing. If VAR is a | |
1140 symbol marked for renaming, this is not necessary, the | |
1141 renamer will use the symbol on the LHS to get its | |
1142 reaching definition. */ | |
1143 FOR_EACH_EDGE (e, ei, bb->preds) | |
1144 add_phi_arg (phi, var, e); | |
1145 } | |
1146 else | |
1147 { | |
1148 gcc_assert (DECL_P (var)); | |
1149 phi = create_phi_node (var, bb); | |
1150 } | |
1151 | |
1152 /* Mark this PHI node as interesting for update_ssa. */ | |
1153 set_register_defs (phi, true); | |
1154 mark_phi_for_rewrite (bb, phi); | |
1155 } | |
1156 } | |
1157 | |
1158 | |
1159 /* Insert PHI nodes at the dominance frontier of blocks with variable | |
1160 definitions. DFS contains the dominance frontier information for | |
1161 the flowgraph. */ | |
1162 | |
1163 static void | |
1164 insert_phi_nodes (bitmap *dfs) | |
1165 { | |
1166 referenced_var_iterator rvi; | |
1167 tree var; | |
1168 | |
1169 timevar_push (TV_TREE_INSERT_PHI_NODES); | |
1170 | |
1171 FOR_EACH_REFERENCED_VAR (var, rvi) | |
1172 { | |
1173 struct def_blocks_d *def_map; | |
1174 bitmap idf; | |
1175 | |
1176 def_map = find_def_blocks_for (var); | |
1177 if (def_map == NULL) | |
1178 continue; | |
1179 | |
1180 if (get_phi_state (var) != NEED_PHI_STATE_NO) | |
1181 { | |
1182 idf = compute_idf (def_map->def_blocks, dfs); | |
1183 insert_phi_nodes_for (var, idf, false); | |
1184 BITMAP_FREE (idf); | |
1185 } | |
1186 } | |
1187 | |
1188 timevar_pop (TV_TREE_INSERT_PHI_NODES); | |
1189 } | |
1190 | |
1191 | |
1192 /* Push SYM's current reaching definition into BLOCK_DEFS_STACK and | |
1193 register DEF (an SSA_NAME) to be a new definition for SYM. */ | |
1194 | |
1195 static void | |
1196 register_new_def (tree def, tree sym) | |
1197 { | |
1198 tree currdef; | |
1199 | |
1200 /* If this variable is set in a single basic block and all uses are | |
1201 dominated by the set(s) in that single basic block, then there is | |
1202 no reason to record anything for this variable in the block local | |
1203 definition stacks. Doing so just wastes time and memory. | |
1204 | |
1205 This is the same test to prune the set of variables which may | |
1206 need PHI nodes. So we just use that information since it's already | |
1207 computed and available for us to use. */ | |
1208 if (get_phi_state (sym) == NEED_PHI_STATE_NO) | |
1209 { | |
1210 set_current_def (sym, def); | |
1211 return; | |
1212 } | |
1213 | |
1214 currdef = get_current_def (sym); | |
1215 | |
1216 /* If SYM is not a GIMPLE register, then CURRDEF may be a name whose | |
1217 SSA_NAME_VAR is not necessarily SYM. In this case, also push SYM | |
1218 in the stack so that we know which symbol is being defined by | |
1219 this SSA name when we unwind the stack. */ | |
1220 if (currdef && !is_gimple_reg (sym)) | |
1221 VEC_safe_push (tree, heap, block_defs_stack, sym); | |
1222 | |
1223 /* Push the current reaching definition into BLOCK_DEFS_STACK. This | |
1224 stack is later used by the dominator tree callbacks to restore | |
1225 the reaching definitions for all the variables defined in the | |
1226 block after a recursive visit to all its immediately dominated | |
1227 blocks. If there is no current reaching definition, then just | |
1228 record the underlying _DECL node. */ | |
1229 VEC_safe_push (tree, heap, block_defs_stack, currdef ? currdef : sym); | |
1230 | |
1231 /* Set the current reaching definition for SYM to be DEF. */ | |
1232 set_current_def (sym, def); | |
1233 } | |
1234 | |
1235 | |
1236 /* Perform a depth-first traversal of the dominator tree looking for | |
1237 variables to rename. BB is the block where to start searching. | |
1238 Renaming is a five step process: | |
1239 | |
1240 1- Every definition made by PHI nodes at the start of the blocks is | |
1241 registered as the current definition for the corresponding variable. | |
1242 | |
1243 2- Every statement in BB is rewritten. USE and VUSE operands are | |
1244 rewritten with their corresponding reaching definition. DEF and | |
1245 VDEF targets are registered as new definitions. | |
1246 | |
1247 3- All the PHI nodes in successor blocks of BB are visited. The | |
1248 argument corresponding to BB is replaced with its current reaching | |
1249 definition. | |
1250 | |
1251 4- Recursively rewrite every dominator child block of BB. | |
1252 | |
1253 5- Restore (in reverse order) the current reaching definition for every | |
1254 new definition introduced in this block. This is done so that when | |
1255 we return from the recursive call, all the current reaching | |
1256 definitions are restored to the names that were valid in the | |
1257 dominator parent of BB. */ | |
1258 | |
1259 /* SSA Rewriting Step 1. Initialization, create a block local stack | |
1260 of reaching definitions for new SSA names produced in this block | |
1261 (BLOCK_DEFS). Register new definitions for every PHI node in the | |
1262 block. */ | |
1263 | |
1264 static void | |
1265 rewrite_initialize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, | |
1266 basic_block bb) | |
1267 { | |
1268 gimple phi; | |
1269 gimple_stmt_iterator gsi; | |
1270 | |
1271 if (dump_file && (dump_flags & TDF_DETAILS)) | |
1272 fprintf (dump_file, "\n\nRenaming block #%d\n\n", bb->index); | |
1273 | |
1274 /* Mark the unwind point for this block. */ | |
1275 VEC_safe_push (tree, heap, block_defs_stack, NULL_TREE); | |
1276 | |
1277 /* Step 1. Register new definitions for every PHI node in the block. | |
1278 Conceptually, all the PHI nodes are executed in parallel and each PHI | |
1279 node introduces a new version for the associated variable. */ | |
1280 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
1281 { | |
1282 tree result; | |
1283 | |
1284 phi = gsi_stmt (gsi); | |
1285 result = gimple_phi_result (phi); | |
1286 gcc_assert (is_gimple_reg (result)); | |
1287 register_new_def (result, SSA_NAME_VAR (result)); | |
1288 } | |
1289 } | |
1290 | |
1291 | |
1292 /* Return the current definition for variable VAR. If none is found, | |
1293 create a new SSA name to act as the zeroth definition for VAR. */ | |
1294 | |
1295 static tree | |
1296 get_reaching_def (tree var) | |
1297 { | |
1298 tree currdef; | |
1299 | |
1300 /* Lookup the current reaching definition for VAR. */ | |
1301 currdef = get_current_def (var); | |
1302 | |
1303 /* If there is no reaching definition for VAR, create and register a | |
1304 default definition for it (if needed). */ | |
1305 if (currdef == NULL_TREE) | |
1306 { | |
1307 tree sym = DECL_P (var) ? var : SSA_NAME_VAR (var); | |
1308 currdef = get_default_def_for (sym); | |
1309 set_current_def (var, currdef); | |
1310 } | |
1311 | |
1312 /* Return the current reaching definition for VAR, or the default | |
1313 definition, if we had to create one. */ | |
1314 return currdef; | |
1315 } | |
1316 | |
1317 | |
1318 /* SSA Rewriting Step 2. Rewrite every variable used in each statement in | |
1319 the block with its immediate reaching definitions. Update the current | |
1320 definition of a variable when a new real or virtual definition is found. */ | |
1321 | |
1322 static void | |
1323 rewrite_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, | |
1324 basic_block bb ATTRIBUTE_UNUSED, gimple_stmt_iterator si) | |
1325 { | |
1326 gimple stmt; | |
1327 use_operand_p use_p; | |
1328 def_operand_p def_p; | |
1329 ssa_op_iter iter; | |
1330 | |
1331 stmt = gsi_stmt (si); | |
1332 | |
1333 /* If mark_def_sites decided that we don't need to rewrite this | |
1334 statement, ignore it. */ | |
1335 gcc_assert (blocks_to_update == NULL); | |
1336 if (!rewrite_uses_p (stmt) && !register_defs_p (stmt)) | |
1337 return; | |
1338 | |
1339 if (dump_file && (dump_flags & TDF_DETAILS)) | |
1340 { | |
1341 fprintf (dump_file, "Renaming statement "); | |
1342 print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); | |
1343 fprintf (dump_file, "\n"); | |
1344 } | |
1345 | |
1346 /* Step 1. Rewrite USES in the statement. */ | |
1347 if (rewrite_uses_p (stmt)) | |
1348 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE) | |
1349 { | |
1350 tree var = USE_FROM_PTR (use_p); | |
1351 gcc_assert (DECL_P (var)); | |
1352 SET_USE (use_p, get_reaching_def (var)); | |
1353 } | |
1354 | |
1355 /* Step 2. Register the statement's DEF operands. */ | |
1356 if (register_defs_p (stmt)) | |
1357 FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_DEF) | |
1358 { | |
1359 tree var = DEF_FROM_PTR (def_p); | |
1360 gcc_assert (DECL_P (var)); | |
1361 SET_DEF (def_p, make_ssa_name (var, stmt)); | |
1362 register_new_def (DEF_FROM_PTR (def_p), var); | |
1363 } | |
1364 } | |
1365 | |
1366 | |
1367 /* SSA Rewriting Step 3. Visit all the successor blocks of BB looking for | |
1368 PHI nodes. For every PHI node found, add a new argument containing the | |
1369 current reaching definition for the variable and the edge through which | |
1370 that definition is reaching the PHI node. */ | |
1371 | |
1372 static void | |
1373 rewrite_add_phi_arguments (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, | |
1374 basic_block bb) | |
1375 { | |
1376 edge e; | |
1377 edge_iterator ei; | |
1378 | |
1379 FOR_EACH_EDGE (e, ei, bb->succs) | |
1380 { | |
1381 gimple phi; | |
1382 gimple_stmt_iterator gsi; | |
1383 | |
1384 for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); | |
1385 gsi_next (&gsi)) | |
1386 { | |
1387 tree currdef; | |
1388 phi = gsi_stmt (gsi); | |
1389 currdef = get_reaching_def (SSA_NAME_VAR (gimple_phi_result (phi))); | |
1390 add_phi_arg (phi, currdef, e); | |
1391 } | |
1392 } | |
1393 } | |
1394 | |
1395 | |
1396 /* Called after visiting all the statements in basic block BB and all | |
1397 of its dominator children. Restore CURRDEFS to its original value. */ | |
1398 | |
1399 static void | |
1400 rewrite_finalize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, | |
1401 basic_block bb ATTRIBUTE_UNUSED) | |
1402 { | |
1403 /* Restore CURRDEFS to its original state. */ | |
1404 while (VEC_length (tree, block_defs_stack) > 0) | |
1405 { | |
1406 tree tmp = VEC_pop (tree, block_defs_stack); | |
1407 tree saved_def, var; | |
1408 | |
1409 if (tmp == NULL_TREE) | |
1410 break; | |
1411 | |
1412 if (TREE_CODE (tmp) == SSA_NAME) | |
1413 { | |
1414 /* If we recorded an SSA_NAME, then make the SSA_NAME the | |
1415 current definition of its underlying variable. Note that | |
1416 if the SSA_NAME is not for a GIMPLE register, the symbol | |
1417 being defined is stored in the next slot in the stack. | |
1418 This mechanism is needed because an SSA name for a | |
1419 non-register symbol may be the definition for more than | |
1420 one symbol (e.g., SFTs, aliased variables, etc). */ | |
1421 saved_def = tmp; | |
1422 var = SSA_NAME_VAR (saved_def); | |
1423 if (!is_gimple_reg (var)) | |
1424 var = VEC_pop (tree, block_defs_stack); | |
1425 } | |
1426 else | |
1427 { | |
1428 /* If we recorded anything else, it must have been a _DECL | |
1429 node and its current reaching definition must have been | |
1430 NULL. */ | |
1431 saved_def = NULL; | |
1432 var = tmp; | |
1433 } | |
1434 | |
1435 set_current_def (var, saved_def); | |
1436 } | |
1437 } | |
1438 | |
1439 | |
1440 /* Dump bitmap SET (assumed to contain VAR_DECLs) to FILE. */ | |
1441 | |
1442 void | |
1443 dump_decl_set (FILE *file, bitmap set) | |
1444 { | |
1445 if (set) | |
1446 { | |
1447 bitmap_iterator bi; | |
1448 unsigned i; | |
1449 | |
1450 fprintf (file, "{ "); | |
1451 | |
1452 EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi) | |
1453 { | |
1454 print_generic_expr (file, referenced_var (i), 0); | |
1455 fprintf (file, " "); | |
1456 } | |
1457 | |
1458 fprintf (file, "}\n"); | |
1459 } | |
1460 else | |
1461 fprintf (file, "NIL\n"); | |
1462 } | |
1463 | |
1464 | |
1465 /* Dump bitmap SET (assumed to contain VAR_DECLs) to FILE. */ | |
1466 | |
1467 void | |
1468 debug_decl_set (bitmap set) | |
1469 { | |
1470 dump_decl_set (stderr, set); | |
1471 } | |
1472 | |
1473 | |
1474 /* Dump the renaming stack (block_defs_stack) to FILE. Traverse the | |
1475 stack up to a maximum of N levels. If N is -1, the whole stack is | |
1476 dumped. New levels are created when the dominator tree traversal | |
1477 used for renaming enters a new sub-tree. */ | |
1478 | |
1479 void | |
1480 dump_defs_stack (FILE *file, int n) | |
1481 { | |
1482 int i, j; | |
1483 | |
1484 fprintf (file, "\n\nRenaming stack"); | |
1485 if (n > 0) | |
1486 fprintf (file, " (up to %d levels)", n); | |
1487 fprintf (file, "\n\n"); | |
1488 | |
1489 i = 1; | |
1490 fprintf (file, "Level %d (current level)\n", i); | |
1491 for (j = (int) VEC_length (tree, block_defs_stack) - 1; j >= 0; j--) | |
1492 { | |
1493 tree name, var; | |
1494 | |
1495 name = VEC_index (tree, block_defs_stack, j); | |
1496 if (name == NULL_TREE) | |
1497 { | |
1498 i++; | |
1499 if (n > 0 && i > n) | |
1500 break; | |
1501 fprintf (file, "\nLevel %d\n", i); | |
1502 continue; | |
1503 } | |
1504 | |
1505 if (DECL_P (name)) | |
1506 { | |
1507 var = name; | |
1508 name = NULL_TREE; | |
1509 } | |
1510 else | |
1511 { | |
1512 var = SSA_NAME_VAR (name); | |
1513 if (!is_gimple_reg (var)) | |
1514 { | |
1515 j--; | |
1516 var = VEC_index (tree, block_defs_stack, j); | |
1517 } | |
1518 } | |
1519 | |
1520 fprintf (file, " Previous CURRDEF ("); | |
1521 print_generic_expr (file, var, 0); | |
1522 fprintf (file, ") = "); | |
1523 if (name) | |
1524 print_generic_expr (file, name, 0); | |
1525 else | |
1526 fprintf (file, "<NIL>"); | |
1527 fprintf (file, "\n"); | |
1528 } | |
1529 } | |
1530 | |
1531 | |
1532 /* Dump the renaming stack (block_defs_stack) to stderr. Traverse the | |
1533 stack up to a maximum of N levels. If N is -1, the whole stack is | |
1534 dumped. New levels are created when the dominator tree traversal | |
1535 used for renaming enters a new sub-tree. */ | |
1536 | |
1537 void | |
1538 debug_defs_stack (int n) | |
1539 { | |
1540 dump_defs_stack (stderr, n); | |
1541 } | |
1542 | |
1543 | |
1544 /* Dump the current reaching definition of every symbol to FILE. */ | |
1545 | |
1546 void | |
1547 dump_currdefs (FILE *file) | |
1548 { | |
1549 referenced_var_iterator i; | |
1550 tree var; | |
1551 | |
1552 fprintf (file, "\n\nCurrent reaching definitions\n\n"); | |
1553 FOR_EACH_REFERENCED_VAR (var, i) | |
1554 if (syms_to_rename == NULL || bitmap_bit_p (syms_to_rename, DECL_UID (var))) | |
1555 { | |
1556 fprintf (file, "CURRDEF ("); | |
1557 print_generic_expr (file, var, 0); | |
1558 fprintf (file, ") = "); | |
1559 if (get_current_def (var)) | |
1560 print_generic_expr (file, get_current_def (var), 0); | |
1561 else | |
1562 fprintf (file, "<NIL>"); | |
1563 fprintf (file, "\n"); | |
1564 } | |
1565 } | |
1566 | |
1567 | |
1568 /* Dump the current reaching definition of every symbol to stderr. */ | |
1569 | |
1570 void | |
1571 debug_currdefs (void) | |
1572 { | |
1573 dump_currdefs (stderr); | |
1574 } | |
1575 | |
1576 | |
1577 /* Dump SSA information to FILE. */ | |
1578 | |
1579 void | |
1580 dump_tree_ssa (FILE *file) | |
1581 { | |
1582 const char *funcname | |
1583 = lang_hooks.decl_printable_name (current_function_decl, 2); | |
1584 | |
1585 fprintf (file, "SSA renaming information for %s\n\n", funcname); | |
1586 | |
1587 dump_def_blocks (file); | |
1588 dump_defs_stack (file, -1); | |
1589 dump_currdefs (file); | |
1590 dump_tree_ssa_stats (file); | |
1591 } | |
1592 | |
1593 | |
1594 /* Dump SSA information to stderr. */ | |
1595 | |
1596 void | |
1597 debug_tree_ssa (void) | |
1598 { | |
1599 dump_tree_ssa (stderr); | |
1600 } | |
1601 | |
1602 | |
1603 /* Dump statistics for the hash table HTAB. */ | |
1604 | |
1605 static void | |
1606 htab_statistics (FILE *file, htab_t htab) | |
1607 { | |
1608 fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n", | |
1609 (long) htab_size (htab), | |
1610 (long) htab_elements (htab), | |
1611 htab_collisions (htab)); | |
1612 } | |
1613 | |
1614 | |
1615 /* Dump SSA statistics on FILE. */ | |
1616 | |
1617 void | |
1618 dump_tree_ssa_stats (FILE *file) | |
1619 { | |
1620 if (def_blocks || repl_tbl) | |
1621 fprintf (file, "\nHash table statistics:\n"); | |
1622 | |
1623 if (def_blocks) | |
1624 { | |
1625 fprintf (file, " def_blocks: "); | |
1626 htab_statistics (file, def_blocks); | |
1627 } | |
1628 | |
1629 if (repl_tbl) | |
1630 { | |
1631 fprintf (file, " repl_tbl: "); | |
1632 htab_statistics (file, repl_tbl); | |
1633 } | |
1634 | |
1635 if (def_blocks || repl_tbl) | |
1636 fprintf (file, "\n"); | |
1637 } | |
1638 | |
1639 | |
1640 /* Dump SSA statistics on stderr. */ | |
1641 | |
1642 void | |
1643 debug_tree_ssa_stats (void) | |
1644 { | |
1645 dump_tree_ssa_stats (stderr); | |
1646 } | |
1647 | |
1648 | |
1649 /* Hashing and equality functions for DEF_BLOCKS. */ | |
1650 | |
1651 static hashval_t | |
1652 def_blocks_hash (const void *p) | |
1653 { | |
1654 return htab_hash_pointer | |
1655 ((const void *)((const struct def_blocks_d *)p)->var); | |
1656 } | |
1657 | |
1658 static int | |
1659 def_blocks_eq (const void *p1, const void *p2) | |
1660 { | |
1661 return ((const struct def_blocks_d *)p1)->var | |
1662 == ((const struct def_blocks_d *)p2)->var; | |
1663 } | |
1664 | |
1665 | |
1666 /* Free memory allocated by one entry in DEF_BLOCKS. */ | |
1667 | |
1668 static void | |
1669 def_blocks_free (void *p) | |
1670 { | |
1671 struct def_blocks_d *entry = (struct def_blocks_d *) p; | |
1672 BITMAP_FREE (entry->def_blocks); | |
1673 BITMAP_FREE (entry->phi_blocks); | |
1674 BITMAP_FREE (entry->livein_blocks); | |
1675 free (entry); | |
1676 } | |
1677 | |
1678 | |
1679 /* Callback for htab_traverse to dump the DEF_BLOCKS hash table. */ | |
1680 | |
1681 static int | |
1682 debug_def_blocks_r (void **slot, void *data) | |
1683 { | |
1684 FILE *file = (FILE *) data; | |
1685 struct def_blocks_d *db_p = (struct def_blocks_d *) *slot; | |
1686 | |
1687 fprintf (file, "VAR: "); | |
1688 print_generic_expr (file, db_p->var, dump_flags); | |
1689 bitmap_print (file, db_p->def_blocks, ", DEF_BLOCKS: { ", "}"); | |
1690 bitmap_print (file, db_p->livein_blocks, ", LIVEIN_BLOCKS: { ", "}"); | |
1691 bitmap_print (file, db_p->phi_blocks, ", PHI_BLOCKS: { ", "}\n"); | |
1692 | |
1693 return 1; | |
1694 } | |
1695 | |
1696 | |
1697 /* Dump the DEF_BLOCKS hash table on FILE. */ | |
1698 | |
1699 void | |
1700 dump_def_blocks (FILE *file) | |
1701 { | |
1702 fprintf (file, "\n\nDefinition and live-in blocks:\n\n"); | |
1703 if (def_blocks) | |
1704 htab_traverse (def_blocks, debug_def_blocks_r, file); | |
1705 } | |
1706 | |
1707 | |
1708 /* Dump the DEF_BLOCKS hash table on stderr. */ | |
1709 | |
1710 void | |
1711 debug_def_blocks (void) | |
1712 { | |
1713 dump_def_blocks (stderr); | |
1714 } | |
1715 | |
1716 | |
1717 /* Register NEW_NAME to be the new reaching definition for OLD_NAME. */ | |
1718 | |
1719 static inline void | |
1720 register_new_update_single (tree new_name, tree old_name) | |
1721 { | |
1722 tree currdef = get_current_def (old_name); | |
1723 | |
1724 /* Push the current reaching definition into BLOCK_DEFS_STACK. | |
1725 This stack is later used by the dominator tree callbacks to | |
1726 restore the reaching definitions for all the variables | |
1727 defined in the block after a recursive visit to all its | |
1728 immediately dominated blocks. */ | |
1729 VEC_reserve (tree, heap, block_defs_stack, 2); | |
1730 VEC_quick_push (tree, block_defs_stack, currdef); | |
1731 VEC_quick_push (tree, block_defs_stack, old_name); | |
1732 | |
1733 /* Set the current reaching definition for OLD_NAME to be | |
1734 NEW_NAME. */ | |
1735 set_current_def (old_name, new_name); | |
1736 } | |
1737 | |
1738 | |
1739 /* Register NEW_NAME to be the new reaching definition for all the | |
1740 names in OLD_NAMES. Used by the incremental SSA update routines to | |
1741 replace old SSA names with new ones. */ | |
1742 | |
1743 static inline void | |
1744 register_new_update_set (tree new_name, bitmap old_names) | |
1745 { | |
1746 bitmap_iterator bi; | |
1747 unsigned i; | |
1748 | |
1749 EXECUTE_IF_SET_IN_BITMAP (old_names, 0, i, bi) | |
1750 register_new_update_single (new_name, ssa_name (i)); | |
1751 } | |
1752 | |
1753 | |
1754 /* Initialization of block data structures for the incremental SSA | |
1755 update pass. Create a block local stack of reaching definitions | |
1756 for new SSA names produced in this block (BLOCK_DEFS). Register | |
1757 new definitions for every PHI node in the block. */ | |
1758 | |
1759 static void | |
1760 rewrite_update_init_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, | |
1761 basic_block bb) | |
1762 { | |
1763 edge e; | |
1764 edge_iterator ei; | |
1765 bool is_abnormal_phi; | |
1766 gimple_stmt_iterator gsi; | |
1767 | |
1768 if (dump_file && (dump_flags & TDF_DETAILS)) | |
1769 fprintf (dump_file, "\n\nRegistering new PHI nodes in block #%d\n\n", | |
1770 bb->index); | |
1771 | |
1772 /* Mark the unwind point for this block. */ | |
1773 VEC_safe_push (tree, heap, block_defs_stack, NULL_TREE); | |
1774 | |
1775 if (!bitmap_bit_p (blocks_to_update, bb->index)) | |
1776 return; | |
1777 | |
1778 /* Mark the LHS if any of the arguments flows through an abnormal | |
1779 edge. */ | |
1780 is_abnormal_phi = false; | |
1781 FOR_EACH_EDGE (e, ei, bb->preds) | |
1782 if (e->flags & EDGE_ABNORMAL) | |
1783 { | |
1784 is_abnormal_phi = true; | |
1785 break; | |
1786 } | |
1787 | |
1788 /* If any of the PHI nodes is a replacement for a name in | |
1789 OLD_SSA_NAMES or it's one of the names in NEW_SSA_NAMES, then | |
1790 register it as a new definition for its corresponding name. Also | |
1791 register definitions for names whose underlying symbols are | |
1792 marked for renaming. */ | |
1793 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
1794 { | |
1795 tree lhs, lhs_sym; | |
1796 gimple phi = gsi_stmt (gsi); | |
1797 | |
1798 if (!register_defs_p (phi)) | |
1799 continue; | |
1800 | |
1801 lhs = gimple_phi_result (phi); | |
1802 lhs_sym = SSA_NAME_VAR (lhs); | |
1803 | |
1804 if (symbol_marked_for_renaming (lhs_sym)) | |
1805 register_new_update_single (lhs, lhs_sym); | |
1806 else | |
1807 { | |
1808 | |
1809 /* If LHS is a new name, register a new definition for all | |
1810 the names replaced by LHS. */ | |
1811 if (is_new_name (lhs)) | |
1812 register_new_update_set (lhs, names_replaced_by (lhs)); | |
1813 | |
1814 /* If LHS is an OLD name, register it as a new definition | |
1815 for itself. */ | |
1816 if (is_old_name (lhs)) | |
1817 register_new_update_single (lhs, lhs); | |
1818 } | |
1819 | |
1820 if (is_abnormal_phi) | |
1821 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs) = 1; | |
1822 } | |
1823 } | |
1824 | |
1825 | |
1826 /* Called after visiting block BB. Unwind BLOCK_DEFS_STACK to restore | |
1827 the current reaching definition of every name re-written in BB to | |
1828 the original reaching definition before visiting BB. This | |
1829 unwinding must be done in the opposite order to what is done in | |
1830 register_new_update_set. */ | |
1831 | |
1832 static void | |
1833 rewrite_update_fini_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, | |
1834 basic_block bb ATTRIBUTE_UNUSED) | |
1835 { | |
1836 while (VEC_length (tree, block_defs_stack) > 0) | |
1837 { | |
1838 tree var = VEC_pop (tree, block_defs_stack); | |
1839 tree saved_def; | |
1840 | |
1841 /* NULL indicates the unwind stop point for this block (see | |
1842 rewrite_update_init_block). */ | |
1843 if (var == NULL) | |
1844 return; | |
1845 | |
1846 saved_def = VEC_pop (tree, block_defs_stack); | |
1847 set_current_def (var, saved_def); | |
1848 } | |
1849 } | |
1850 | |
1851 | |
1852 /* If the operand pointed to by USE_P is a name in OLD_SSA_NAMES or | |
1853 it is a symbol marked for renaming, replace it with USE_P's current | |
1854 reaching definition. */ | |
1855 | |
1856 static inline void | |
1857 maybe_replace_use (use_operand_p use_p) | |
1858 { | |
1859 tree rdef = NULL_TREE; | |
1860 tree use = USE_FROM_PTR (use_p); | |
1861 tree sym = DECL_P (use) ? use : SSA_NAME_VAR (use); | |
1862 | |
1863 if (symbol_marked_for_renaming (sym)) | |
1864 rdef = get_reaching_def (sym); | |
1865 else if (is_old_name (use)) | |
1866 rdef = get_reaching_def (use); | |
1867 | |
1868 if (rdef && rdef != use) | |
1869 SET_USE (use_p, rdef); | |
1870 } | |
1871 | |
1872 | |
1873 /* If the operand pointed to by DEF_P is an SSA name in NEW_SSA_NAMES | |
1874 or OLD_SSA_NAMES, or if it is a symbol marked for renaming, | |
1875 register it as the current definition for the names replaced by | |
1876 DEF_P. */ | |
1877 | |
1878 static inline void | |
1879 maybe_register_def (def_operand_p def_p, gimple stmt) | |
1880 { | |
1881 tree def = DEF_FROM_PTR (def_p); | |
1882 tree sym = DECL_P (def) ? def : SSA_NAME_VAR (def); | |
1883 | |
1884 /* If DEF is a naked symbol that needs renaming, create a new | |
1885 name for it. */ | |
1886 if (symbol_marked_for_renaming (sym)) | |
1887 { | |
1888 if (DECL_P (def)) | |
1889 { | |
1890 def = make_ssa_name (def, stmt); | |
1891 SET_DEF (def_p, def); | |
1892 } | |
1893 | |
1894 register_new_update_single (def, sym); | |
1895 } | |
1896 else | |
1897 { | |
1898 /* If DEF is a new name, register it as a new definition | |
1899 for all the names replaced by DEF. */ | |
1900 if (is_new_name (def)) | |
1901 register_new_update_set (def, names_replaced_by (def)); | |
1902 | |
1903 /* If DEF is an old name, register DEF as a new | |
1904 definition for itself. */ | |
1905 if (is_old_name (def)) | |
1906 register_new_update_single (def, def); | |
1907 } | |
1908 } | |
1909 | |
1910 | |
1911 /* Update every variable used in the statement pointed-to by SI. The | |
1912 statement is assumed to be in SSA form already. Names in | |
1913 OLD_SSA_NAMES used by SI will be updated to their current reaching | |
1914 definition. Names in OLD_SSA_NAMES or NEW_SSA_NAMES defined by SI | |
1915 will be registered as a new definition for their corresponding name | |
1916 in OLD_SSA_NAMES. */ | |
1917 | |
1918 static void | |
1919 rewrite_update_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, | |
1920 basic_block bb ATTRIBUTE_UNUSED, | |
1921 gimple_stmt_iterator si) | |
1922 { | |
1923 gimple stmt; | |
1924 use_operand_p use_p; | |
1925 def_operand_p def_p; | |
1926 ssa_op_iter iter; | |
1927 | |
1928 stmt = gsi_stmt (si); | |
1929 | |
1930 gcc_assert (bitmap_bit_p (blocks_to_update, bb->index)); | |
1931 | |
1932 /* Only update marked statements. */ | |
1933 if (!rewrite_uses_p (stmt) && !register_defs_p (stmt)) | |
1934 return; | |
1935 | |
1936 if (dump_file && (dump_flags & TDF_DETAILS)) | |
1937 { | |
1938 fprintf (dump_file, "Updating SSA information for statement "); | |
1939 print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); | |
1940 fprintf (dump_file, "\n"); | |
1941 } | |
1942 | |
1943 /* Rewrite USES included in OLD_SSA_NAMES and USES whose underlying | |
1944 symbol is marked for renaming. */ | |
1945 if (rewrite_uses_p (stmt)) | |
1946 { | |
1947 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE) | |
1948 maybe_replace_use (use_p); | |
1949 | |
1950 if (need_to_update_vops_p) | |
1951 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_VIRTUAL_USES) | |
1952 maybe_replace_use (use_p); | |
1953 } | |
1954 | |
1955 /* Register definitions of names in NEW_SSA_NAMES and OLD_SSA_NAMES. | |
1956 Also register definitions for names whose underlying symbol is | |
1957 marked for renaming. */ | |
1958 if (register_defs_p (stmt)) | |
1959 { | |
1960 FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_DEF) | |
1961 maybe_register_def (def_p, stmt); | |
1962 | |
1963 if (need_to_update_vops_p) | |
1964 FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_VIRTUAL_DEFS) | |
1965 maybe_register_def (def_p, stmt); | |
1966 } | |
1967 } | |
1968 | |
1969 | |
1970 /* Visit all the successor blocks of BB looking for PHI nodes. For | |
1971 every PHI node found, check if any of its arguments is in | |
1972 OLD_SSA_NAMES. If so, and if the argument has a current reaching | |
1973 definition, replace it. */ | |
1974 | |
1975 static void | |
1976 rewrite_update_phi_arguments (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, | |
1977 basic_block bb) | |
1978 { | |
1979 edge e; | |
1980 edge_iterator ei; | |
1981 unsigned i; | |
1982 | |
1983 FOR_EACH_EDGE (e, ei, bb->succs) | |
1984 { | |
1985 gimple phi; | |
1986 gimple_vec phis; | |
1987 | |
1988 if (!bitmap_bit_p (blocks_with_phis_to_rewrite, e->dest->index)) | |
1989 continue; | |
1990 | |
1991 phis = VEC_index (gimple_vec, phis_to_rewrite, e->dest->index); | |
1992 for (i = 0; VEC_iterate (gimple, phis, i, phi); i++) | |
1993 { | |
1994 tree arg, lhs_sym; | |
1995 use_operand_p arg_p; | |
1996 | |
1997 gcc_assert (rewrite_uses_p (phi)); | |
1998 | |
1999 arg_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, e); | |
2000 arg = USE_FROM_PTR (arg_p); | |
2001 | |
2002 if (arg && !DECL_P (arg) && TREE_CODE (arg) != SSA_NAME) | |
2003 continue; | |
2004 | |
2005 lhs_sym = SSA_NAME_VAR (gimple_phi_result (phi)); | |
2006 | |
2007 if (arg == NULL_TREE) | |
2008 { | |
2009 /* When updating a PHI node for a recently introduced | |
2010 symbol we may find NULL arguments. That's why we | |
2011 take the symbol from the LHS of the PHI node. */ | |
2012 SET_USE (arg_p, get_reaching_def (lhs_sym)); | |
2013 } | |
2014 else | |
2015 { | |
2016 tree sym = DECL_P (arg) ? arg : SSA_NAME_VAR (arg); | |
2017 | |
2018 if (symbol_marked_for_renaming (sym)) | |
2019 SET_USE (arg_p, get_reaching_def (sym)); | |
2020 else if (is_old_name (arg)) | |
2021 SET_USE (arg_p, get_reaching_def (arg)); | |
2022 } | |
2023 | |
2024 if (e->flags & EDGE_ABNORMAL) | |
2025 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (arg_p)) = 1; | |
2026 } | |
2027 } | |
2028 } | |
2029 | |
2030 | |
2031 /* Rewrite the actual blocks, statements, and PHI arguments, to be in SSA | |
2032 form. | |
2033 | |
2034 ENTRY indicates the block where to start. Every block dominated by | |
2035 ENTRY will be rewritten. | |
2036 | |
2037 WHAT indicates what actions will be taken by the renamer (see enum | |
2038 rewrite_mode). | |
2039 | |
2040 BLOCKS are the set of interesting blocks for the dominator walker | |
2041 to process. If this set is NULL, then all the nodes dominated | |
2042 by ENTRY are walked. Otherwise, blocks dominated by ENTRY that | |
2043 are not present in BLOCKS are ignored. */ | |
2044 | |
2045 static void | |
2046 rewrite_blocks (basic_block entry, enum rewrite_mode what, sbitmap blocks) | |
2047 { | |
2048 struct dom_walk_data walk_data; | |
2049 | |
2050 /* Rewrite all the basic blocks in the program. */ | |
2051 timevar_push (TV_TREE_SSA_REWRITE_BLOCKS); | |
2052 | |
2053 /* Setup callbacks for the generic dominator tree walker. */ | |
2054 memset (&walk_data, 0, sizeof (walk_data)); | |
2055 | |
2056 walk_data.dom_direction = CDI_DOMINATORS; | |
2057 walk_data.interesting_blocks = blocks; | |
2058 | |
2059 if (what == REWRITE_ALL) | |
2060 walk_data.before_dom_children_before_stmts = rewrite_initialize_block; | |
2061 else | |
2062 walk_data.before_dom_children_before_stmts = rewrite_update_init_block; | |
2063 | |
2064 if (what == REWRITE_ALL) | |
2065 walk_data.before_dom_children_walk_stmts = rewrite_stmt; | |
2066 else if (what == REWRITE_UPDATE) | |
2067 walk_data.before_dom_children_walk_stmts = rewrite_update_stmt; | |
2068 else | |
2069 gcc_unreachable (); | |
2070 | |
2071 if (what == REWRITE_ALL) | |
2072 walk_data.before_dom_children_after_stmts = rewrite_add_phi_arguments; | |
2073 else if (what == REWRITE_UPDATE) | |
2074 walk_data.before_dom_children_after_stmts = rewrite_update_phi_arguments; | |
2075 else | |
2076 gcc_unreachable (); | |
2077 | |
2078 if (what == REWRITE_ALL) | |
2079 walk_data.after_dom_children_after_stmts = rewrite_finalize_block; | |
2080 else if (what == REWRITE_UPDATE) | |
2081 walk_data.after_dom_children_after_stmts = rewrite_update_fini_block; | |
2082 else | |
2083 gcc_unreachable (); | |
2084 | |
2085 block_defs_stack = VEC_alloc (tree, heap, 10); | |
2086 | |
2087 /* Initialize the dominator walker. */ | |
2088 init_walk_dominator_tree (&walk_data); | |
2089 | |
2090 /* Recursively walk the dominator tree rewriting each statement in | |
2091 each basic block. */ | |
2092 walk_dominator_tree (&walk_data, entry); | |
2093 | |
2094 /* Finalize the dominator walker. */ | |
2095 fini_walk_dominator_tree (&walk_data); | |
2096 | |
2097 /* Debugging dumps. */ | |
2098 if (dump_file && (dump_flags & TDF_STATS)) | |
2099 { | |
2100 dump_dfa_stats (dump_file); | |
2101 if (def_blocks) | |
2102 dump_tree_ssa_stats (dump_file); | |
2103 } | |
2104 | |
2105 VEC_free (tree, heap, block_defs_stack); | |
2106 | |
2107 timevar_pop (TV_TREE_SSA_REWRITE_BLOCKS); | |
2108 } | |
2109 | |
2110 | |
2111 /* Block initialization routine for mark_def_sites. Clear the | |
2112 KILLS bitmap at the start of each block. */ | |
2113 | |
2114 static void | |
2115 mark_def_sites_initialize_block (struct dom_walk_data *walk_data, | |
2116 basic_block bb ATTRIBUTE_UNUSED) | |
2117 { | |
2118 struct mark_def_sites_global_data *gd; | |
2119 gd = (struct mark_def_sites_global_data *) walk_data->global_data; | |
2120 bitmap_clear (gd->kills); | |
2121 } | |
2122 | |
2123 | |
2124 /* Mark the definition site blocks for each variable, so that we know | |
2125 where the variable is actually live. | |
2126 | |
2127 INTERESTING_BLOCKS will be filled in with all the blocks that | |
2128 should be processed by the renamer. It is assumed to be | |
2129 initialized and zeroed by the caller. */ | |
2130 | |
2131 static void | |
2132 mark_def_site_blocks (sbitmap interesting_blocks) | |
2133 { | |
2134 struct dom_walk_data walk_data; | |
2135 struct mark_def_sites_global_data mark_def_sites_global_data; | |
2136 | |
2137 /* Setup callbacks for the generic dominator tree walker to find and | |
2138 mark definition sites. */ | |
2139 walk_data.walk_stmts_backward = false; | |
2140 walk_data.dom_direction = CDI_DOMINATORS; | |
2141 walk_data.initialize_block_local_data = NULL; | |
2142 walk_data.before_dom_children_before_stmts = mark_def_sites_initialize_block; | |
2143 walk_data.before_dom_children_walk_stmts = mark_def_sites; | |
2144 walk_data.before_dom_children_after_stmts = NULL; | |
2145 walk_data.after_dom_children_before_stmts = NULL; | |
2146 walk_data.after_dom_children_walk_stmts = NULL; | |
2147 walk_data.after_dom_children_after_stmts = NULL; | |
2148 walk_data.interesting_blocks = NULL; | |
2149 | |
2150 /* Notice that this bitmap is indexed using variable UIDs, so it must be | |
2151 large enough to accommodate all the variables referenced in the | |
2152 function, not just the ones we are renaming. */ | |
2153 mark_def_sites_global_data.kills = BITMAP_ALLOC (NULL); | |
2154 | |
2155 /* Create the set of interesting blocks that will be filled by | |
2156 mark_def_sites. */ | |
2157 mark_def_sites_global_data.interesting_blocks = interesting_blocks; | |
2158 walk_data.global_data = &mark_def_sites_global_data; | |
2159 | |
2160 /* We do not have any local data. */ | |
2161 walk_data.block_local_data_size = 0; | |
2162 | |
2163 /* Initialize the dominator walker. */ | |
2164 init_walk_dominator_tree (&walk_data); | |
2165 | |
2166 /* Recursively walk the dominator tree. */ | |
2167 walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR); | |
2168 | |
2169 /* Finalize the dominator walker. */ | |
2170 fini_walk_dominator_tree (&walk_data); | |
2171 | |
2172 /* We no longer need this bitmap, clear and free it. */ | |
2173 BITMAP_FREE (mark_def_sites_global_data.kills); | |
2174 } | |
2175 | |
2176 | |
2177 /* Initialize internal data needed during renaming. */ | |
2178 | |
2179 static void | |
2180 init_ssa_renamer (void) | |
2181 { | |
2182 tree var; | |
2183 referenced_var_iterator rvi; | |
2184 | |
2185 cfun->gimple_df->in_ssa_p = false; | |
2186 | |
2187 /* Allocate memory for the DEF_BLOCKS hash table. */ | |
2188 gcc_assert (def_blocks == NULL); | |
2189 def_blocks = htab_create (num_referenced_vars, def_blocks_hash, | |
2190 def_blocks_eq, def_blocks_free); | |
2191 | |
2192 FOR_EACH_REFERENCED_VAR(var, rvi) | |
2193 set_current_def (var, NULL_TREE); | |
2194 } | |
2195 | |
2196 | |
2197 /* Deallocate internal data structures used by the renamer. */ | |
2198 | |
2199 static void | |
2200 fini_ssa_renamer (void) | |
2201 { | |
2202 if (def_blocks) | |
2203 { | |
2204 htab_delete (def_blocks); | |
2205 def_blocks = NULL; | |
2206 } | |
2207 | |
2208 cfun->gimple_df->in_ssa_p = true; | |
2209 } | |
2210 | |
2211 /* Main entry point into the SSA builder. The renaming process | |
2212 proceeds in four main phases: | |
2213 | |
2214 1- Compute dominance frontier and immediate dominators, needed to | |
2215 insert PHI nodes and rename the function in dominator tree | |
2216 order. | |
2217 | |
2218 2- Find and mark all the blocks that define variables | |
2219 (mark_def_site_blocks). | |
2220 | |
2221 3- Insert PHI nodes at dominance frontiers (insert_phi_nodes). | |
2222 | |
2223 4- Rename all the blocks (rewrite_blocks) and statements in the program. | |
2224 | |
2225 Steps 3 and 4 are done using the dominator tree walker | |
2226 (walk_dominator_tree). */ | |
2227 | |
2228 static unsigned int | |
2229 rewrite_into_ssa (void) | |
2230 { | |
2231 bitmap *dfs; | |
2232 basic_block bb; | |
2233 sbitmap interesting_blocks; | |
2234 | |
2235 timevar_push (TV_TREE_SSA_OTHER); | |
2236 | |
2237 /* Initialize operand data structures. */ | |
2238 init_ssa_operands (); | |
2239 | |
2240 /* Initialize internal data needed by the renamer. */ | |
2241 init_ssa_renamer (); | |
2242 | |
2243 /* Initialize the set of interesting blocks. The callback | |
2244 mark_def_sites will add to this set those blocks that the renamer | |
2245 should process. */ | |
2246 interesting_blocks = sbitmap_alloc (last_basic_block); | |
2247 sbitmap_zero (interesting_blocks); | |
2248 | |
2249 /* Initialize dominance frontier. */ | |
2250 dfs = XNEWVEC (bitmap, last_basic_block); | |
2251 FOR_EACH_BB (bb) | |
2252 dfs[bb->index] = BITMAP_ALLOC (NULL); | |
2253 | |
2254 /* 1- Compute dominance frontiers. */ | |
2255 calculate_dominance_info (CDI_DOMINATORS); | |
2256 compute_dominance_frontiers (dfs); | |
2257 | |
2258 /* 2- Find and mark definition sites. */ | |
2259 mark_def_site_blocks (interesting_blocks); | |
2260 | |
2261 /* 3- Insert PHI nodes at dominance frontiers of definition blocks. */ | |
2262 insert_phi_nodes (dfs); | |
2263 | |
2264 /* 4- Rename all the blocks. */ | |
2265 rewrite_blocks (ENTRY_BLOCK_PTR, REWRITE_ALL, interesting_blocks); | |
2266 | |
2267 /* Free allocated memory. */ | |
2268 FOR_EACH_BB (bb) | |
2269 BITMAP_FREE (dfs[bb->index]); | |
2270 free (dfs); | |
2271 sbitmap_free (interesting_blocks); | |
2272 | |
2273 fini_ssa_renamer (); | |
2274 | |
2275 timevar_pop (TV_TREE_SSA_OTHER); | |
2276 return 0; | |
2277 } | |
2278 | |
2279 | |
2280 struct gimple_opt_pass pass_build_ssa = | |
2281 { | |
2282 { | |
2283 GIMPLE_PASS, | |
2284 "ssa", /* name */ | |
2285 NULL, /* gate */ | |
2286 rewrite_into_ssa, /* execute */ | |
2287 NULL, /* sub */ | |
2288 NULL, /* next */ | |
2289 0, /* static_pass_number */ | |
2290 0, /* tv_id */ | |
2291 PROP_cfg | PROP_referenced_vars, /* properties_required */ | |
2292 PROP_ssa, /* properties_provided */ | |
2293 0, /* properties_destroyed */ | |
2294 0, /* todo_flags_start */ | |
2295 TODO_dump_func | |
2296 | TODO_verify_ssa | |
2297 | TODO_remove_unused_locals /* todo_flags_finish */ | |
2298 } | |
2299 }; | |
2300 | |
2301 | |
2302 /* Mark the definition of VAR at STMT and BB as interesting for the | |
2303 renamer. BLOCKS is the set of blocks that need updating. */ | |
2304 | |
2305 static void | |
2306 mark_def_interesting (tree var, gimple stmt, basic_block bb, bool insert_phi_p) | |
2307 { | |
2308 gcc_assert (bitmap_bit_p (blocks_to_update, bb->index)); | |
2309 set_register_defs (stmt, true); | |
2310 | |
2311 if (insert_phi_p) | |
2312 { | |
2313 bool is_phi_p = gimple_code (stmt) == GIMPLE_PHI; | |
2314 | |
2315 set_def_block (var, bb, is_phi_p); | |
2316 | |
2317 /* If VAR is an SSA name in NEW_SSA_NAMES, this is a definition | |
2318 site for both itself and all the old names replaced by it. */ | |
2319 if (TREE_CODE (var) == SSA_NAME && is_new_name (var)) | |
2320 { | |
2321 bitmap_iterator bi; | |
2322 unsigned i; | |
2323 bitmap set = names_replaced_by (var); | |
2324 if (set) | |
2325 EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi) | |
2326 set_def_block (ssa_name (i), bb, is_phi_p); | |
2327 } | |
2328 } | |
2329 } | |
2330 | |
2331 | |
2332 /* Mark the use of VAR at STMT and BB as interesting for the | |
2333 renamer. INSERT_PHI_P is true if we are going to insert new PHI | |
2334 nodes. */ | |
2335 | |
2336 static inline void | |
2337 mark_use_interesting (tree var, gimple stmt, basic_block bb, bool insert_phi_p) | |
2338 { | |
2339 basic_block def_bb = gimple_bb (stmt); | |
2340 | |
2341 mark_block_for_update (def_bb); | |
2342 mark_block_for_update (bb); | |
2343 | |
2344 if (gimple_code (stmt) == GIMPLE_PHI) | |
2345 mark_phi_for_rewrite (def_bb, stmt); | |
2346 else | |
2347 set_rewrite_uses (stmt, true); | |
2348 | |
2349 /* If VAR has not been defined in BB, then it is live-on-entry | |
2350 to BB. Note that we cannot just use the block holding VAR's | |
2351 definition because if VAR is one of the names in OLD_SSA_NAMES, | |
2352 it will have several definitions (itself and all the names that | |
2353 replace it). */ | |
2354 if (insert_phi_p) | |
2355 { | |
2356 struct def_blocks_d *db_p = get_def_blocks_for (var); | |
2357 if (!bitmap_bit_p (db_p->def_blocks, bb->index)) | |
2358 set_livein_block (var, bb); | |
2359 } | |
2360 } | |
2361 | |
2362 | |
2363 /* Do a dominator walk starting at BB processing statements that | |
2364 reference symbols in SYMS_TO_RENAME. This is very similar to | |
2365 mark_def_sites, but the scan handles statements whose operands may | |
2366 already be SSA names. | |
2367 | |
2368 If INSERT_PHI_P is true, mark those uses as live in the | |
2369 corresponding block. This is later used by the PHI placement | |
2370 algorithm to make PHI pruning decisions. | |
2371 | |
2372 FIXME. Most of this would be unnecessary if we could associate a | |
2373 symbol to all the SSA names that reference it. But that | |
2374 sounds like it would be expensive to maintain. Still, it | |
2375 would be interesting to see if it makes better sense to do | |
2376 that. */ | |
2377 | |
2378 static void | |
2379 prepare_block_for_update (basic_block bb, bool insert_phi_p) | |
2380 { | |
2381 basic_block son; | |
2382 gimple_stmt_iterator si; | |
2383 edge e; | |
2384 edge_iterator ei; | |
2385 | |
2386 mark_block_for_update (bb); | |
2387 | |
2388 /* Process PHI nodes marking interesting those that define or use | |
2389 the symbols that we are interested in. */ | |
2390 for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si)) | |
2391 { | |
2392 gimple phi = gsi_stmt (si); | |
2393 tree lhs_sym, lhs = gimple_phi_result (phi); | |
2394 | |
2395 lhs_sym = DECL_P (lhs) ? lhs : SSA_NAME_VAR (lhs); | |
2396 | |
2397 if (!symbol_marked_for_renaming (lhs_sym)) | |
2398 continue; | |
2399 | |
2400 mark_def_interesting (lhs_sym, phi, bb, insert_phi_p); | |
2401 | |
2402 /* Mark the uses in phi nodes as interesting. It would be more correct | |
2403 to process the arguments of the phi nodes of the successor edges of | |
2404 BB at the end of prepare_block_for_update, however, that turns out | |
2405 to be significantly more expensive. Doing it here is conservatively | |
2406 correct -- it may only cause us to believe a value to be live in a | |
2407 block that also contains its definition, and thus insert a few more | |
2408 phi nodes for it. */ | |
2409 FOR_EACH_EDGE (e, ei, bb->preds) | |
2410 mark_use_interesting (lhs_sym, phi, e->src, insert_phi_p); | |
2411 } | |
2412 | |
2413 /* Process the statements. */ | |
2414 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si)) | |
2415 { | |
2416 gimple stmt; | |
2417 ssa_op_iter i; | |
2418 use_operand_p use_p; | |
2419 def_operand_p def_p; | |
2420 | |
2421 stmt = gsi_stmt (si); | |
2422 | |
2423 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, i, SSA_OP_ALL_USES) | |
2424 { | |
2425 tree use = USE_FROM_PTR (use_p); | |
2426 tree sym = DECL_P (use) ? use : SSA_NAME_VAR (use); | |
2427 if (symbol_marked_for_renaming (sym)) | |
2428 mark_use_interesting (sym, stmt, bb, insert_phi_p); | |
2429 } | |
2430 | |
2431 FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, i, SSA_OP_ALL_DEFS) | |
2432 { | |
2433 tree def = DEF_FROM_PTR (def_p); | |
2434 tree sym = DECL_P (def) ? def : SSA_NAME_VAR (def); | |
2435 if (symbol_marked_for_renaming (sym)) | |
2436 mark_def_interesting (sym, stmt, bb, insert_phi_p); | |
2437 } | |
2438 } | |
2439 | |
2440 /* Now visit all the blocks dominated by BB. */ | |
2441 for (son = first_dom_son (CDI_DOMINATORS, bb); | |
2442 son; | |
2443 son = next_dom_son (CDI_DOMINATORS, son)) | |
2444 prepare_block_for_update (son, insert_phi_p); | |
2445 } | |
2446 | |
2447 | |
2448 /* Helper for prepare_names_to_update. Mark all the use sites for | |
2449 NAME as interesting. BLOCKS and INSERT_PHI_P are as in | |
2450 prepare_names_to_update. */ | |
2451 | |
2452 static void | |
2453 prepare_use_sites_for (tree name, bool insert_phi_p) | |
2454 { | |
2455 use_operand_p use_p; | |
2456 imm_use_iterator iter; | |
2457 | |
2458 FOR_EACH_IMM_USE_FAST (use_p, iter, name) | |
2459 { | |
2460 gimple stmt = USE_STMT (use_p); | |
2461 basic_block bb = gimple_bb (stmt); | |
2462 | |
2463 if (gimple_code (stmt) == GIMPLE_PHI) | |
2464 { | |
2465 int ix = PHI_ARG_INDEX_FROM_USE (use_p); | |
2466 edge e = gimple_phi_arg_edge (stmt, ix); | |
2467 mark_use_interesting (name, stmt, e->src, insert_phi_p); | |
2468 } | |
2469 else | |
2470 { | |
2471 /* For regular statements, mark this as an interesting use | |
2472 for NAME. */ | |
2473 mark_use_interesting (name, stmt, bb, insert_phi_p); | |
2474 } | |
2475 } | |
2476 } | |
2477 | |
2478 | |
2479 /* Helper for prepare_names_to_update. Mark the definition site for | |
2480 NAME as interesting. BLOCKS and INSERT_PHI_P are as in | |
2481 prepare_names_to_update. */ | |
2482 | |
2483 static void | |
2484 prepare_def_site_for (tree name, bool insert_phi_p) | |
2485 { | |
2486 gimple stmt; | |
2487 basic_block bb; | |
2488 | |
2489 gcc_assert (names_to_release == NULL | |
2490 || !bitmap_bit_p (names_to_release, SSA_NAME_VERSION (name))); | |
2491 | |
2492 stmt = SSA_NAME_DEF_STMT (name); | |
2493 bb = gimple_bb (stmt); | |
2494 if (bb) | |
2495 { | |
2496 gcc_assert (bb->index < last_basic_block); | |
2497 mark_block_for_update (bb); | |
2498 mark_def_interesting (name, stmt, bb, insert_phi_p); | |
2499 } | |
2500 } | |
2501 | |
2502 | |
2503 /* Mark definition and use sites of names in NEW_SSA_NAMES and | |
2504 OLD_SSA_NAMES. INSERT_PHI_P is true if the caller wants to insert | |
2505 PHI nodes for newly created names. */ | |
2506 | |
2507 static void | |
2508 prepare_names_to_update (bool insert_phi_p) | |
2509 { | |
2510 unsigned i = 0; | |
2511 bitmap_iterator bi; | |
2512 sbitmap_iterator sbi; | |
2513 | |
2514 /* If a name N from NEW_SSA_NAMES is also marked to be released, | |
2515 remove it from NEW_SSA_NAMES so that we don't try to visit its | |
2516 defining basic block (which most likely doesn't exist). Notice | |
2517 that we cannot do the same with names in OLD_SSA_NAMES because we | |
2518 want to replace existing instances. */ | |
2519 if (names_to_release) | |
2520 EXECUTE_IF_SET_IN_BITMAP (names_to_release, 0, i, bi) | |
2521 RESET_BIT (new_ssa_names, i); | |
2522 | |
2523 /* First process names in NEW_SSA_NAMES. Otherwise, uses of old | |
2524 names may be considered to be live-in on blocks that contain | |
2525 definitions for their replacements. */ | |
2526 EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi) | |
2527 prepare_def_site_for (ssa_name (i), insert_phi_p); | |
2528 | |
2529 /* If an old name is in NAMES_TO_RELEASE, we cannot remove it from | |
2530 OLD_SSA_NAMES, but we have to ignore its definition site. */ | |
2531 EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi) | |
2532 { | |
2533 if (names_to_release == NULL || !bitmap_bit_p (names_to_release, i)) | |
2534 prepare_def_site_for (ssa_name (i), insert_phi_p); | |
2535 prepare_use_sites_for (ssa_name (i), insert_phi_p); | |
2536 } | |
2537 } | |
2538 | |
2539 | |
2540 /* Dump all the names replaced by NAME to FILE. */ | |
2541 | |
2542 void | |
2543 dump_names_replaced_by (FILE *file, tree name) | |
2544 { | |
2545 unsigned i; | |
2546 bitmap old_set; | |
2547 bitmap_iterator bi; | |
2548 | |
2549 print_generic_expr (file, name, 0); | |
2550 fprintf (file, " -> { "); | |
2551 | |
2552 old_set = names_replaced_by (name); | |
2553 EXECUTE_IF_SET_IN_BITMAP (old_set, 0, i, bi) | |
2554 { | |
2555 print_generic_expr (file, ssa_name (i), 0); | |
2556 fprintf (file, " "); | |
2557 } | |
2558 | |
2559 fprintf (file, "}\n"); | |
2560 } | |
2561 | |
2562 | |
2563 /* Dump all the names replaced by NAME to stderr. */ | |
2564 | |
2565 void | |
2566 debug_names_replaced_by (tree name) | |
2567 { | |
2568 dump_names_replaced_by (stderr, name); | |
2569 } | |
2570 | |
2571 | |
2572 /* Dump SSA update information to FILE. */ | |
2573 | |
2574 void | |
2575 dump_update_ssa (FILE *file) | |
2576 { | |
2577 unsigned i = 0; | |
2578 bitmap_iterator bi; | |
2579 | |
2580 if (!need_ssa_update_p ()) | |
2581 return; | |
2582 | |
2583 if (new_ssa_names && sbitmap_first_set_bit (new_ssa_names) >= 0) | |
2584 { | |
2585 sbitmap_iterator sbi; | |
2586 | |
2587 fprintf (file, "\nSSA replacement table\n"); | |
2588 fprintf (file, "N_i -> { O_1 ... O_j } means that N_i replaces " | |
2589 "O_1, ..., O_j\n\n"); | |
2590 | |
2591 EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi) | |
2592 dump_names_replaced_by (file, ssa_name (i)); | |
2593 | |
2594 fprintf (file, "\n"); | |
2595 fprintf (file, "Number of virtual NEW -> OLD mappings: %7u\n", | |
2596 update_ssa_stats.num_virtual_mappings); | |
2597 fprintf (file, "Number of real NEW -> OLD mappings: %7u\n", | |
2598 update_ssa_stats.num_total_mappings | |
2599 - update_ssa_stats.num_virtual_mappings); | |
2600 fprintf (file, "Number of total NEW -> OLD mappings: %7u\n", | |
2601 update_ssa_stats.num_total_mappings); | |
2602 | |
2603 fprintf (file, "\nNumber of virtual symbols: %u\n", | |
2604 update_ssa_stats.num_virtual_symbols); | |
2605 } | |
2606 | |
2607 if (syms_to_rename && !bitmap_empty_p (syms_to_rename)) | |
2608 { | |
2609 fprintf (file, "\n\nSymbols to be put in SSA form\n\n"); | |
2610 dump_decl_set (file, syms_to_rename); | |
2611 } | |
2612 | |
2613 if (names_to_release && !bitmap_empty_p (names_to_release)) | |
2614 { | |
2615 fprintf (file, "\n\nSSA names to release after updating the SSA web\n\n"); | |
2616 EXECUTE_IF_SET_IN_BITMAP (names_to_release, 0, i, bi) | |
2617 { | |
2618 print_generic_expr (file, ssa_name (i), 0); | |
2619 fprintf (file, " "); | |
2620 } | |
2621 } | |
2622 | |
2623 fprintf (file, "\n\n"); | |
2624 } | |
2625 | |
2626 | |
2627 /* Dump SSA update information to stderr. */ | |
2628 | |
2629 void | |
2630 debug_update_ssa (void) | |
2631 { | |
2632 dump_update_ssa (stderr); | |
2633 } | |
2634 | |
2635 | |
2636 /* Initialize data structures used for incremental SSA updates. */ | |
2637 | |
2638 static void | |
2639 init_update_ssa (void) | |
2640 { | |
2641 /* Reserve more space than the current number of names. The calls to | |
2642 add_new_name_mapping are typically done after creating new SSA | |
2643 names, so we'll need to reallocate these arrays. */ | |
2644 old_ssa_names = sbitmap_alloc (num_ssa_names + NAME_SETS_GROWTH_FACTOR); | |
2645 sbitmap_zero (old_ssa_names); | |
2646 | |
2647 new_ssa_names = sbitmap_alloc (num_ssa_names + NAME_SETS_GROWTH_FACTOR); | |
2648 sbitmap_zero (new_ssa_names); | |
2649 | |
2650 repl_tbl = htab_create (20, repl_map_hash, repl_map_eq, repl_map_free); | |
2651 need_to_initialize_update_ssa_p = false; | |
2652 need_to_update_vops_p = false; | |
2653 syms_to_rename = BITMAP_ALLOC (NULL); | |
2654 regs_to_rename = BITMAP_ALLOC (NULL); | |
2655 mem_syms_to_rename = BITMAP_ALLOC (NULL); | |
2656 names_to_release = NULL; | |
2657 memset (&update_ssa_stats, 0, sizeof (update_ssa_stats)); | |
2658 update_ssa_stats.virtual_symbols = BITMAP_ALLOC (NULL); | |
2659 } | |
2660 | |
2661 | |
2662 /* Deallocate data structures used for incremental SSA updates. */ | |
2663 | |
2664 void | |
2665 delete_update_ssa (void) | |
2666 { | |
2667 unsigned i; | |
2668 bitmap_iterator bi; | |
2669 | |
2670 sbitmap_free (old_ssa_names); | |
2671 old_ssa_names = NULL; | |
2672 | |
2673 sbitmap_free (new_ssa_names); | |
2674 new_ssa_names = NULL; | |
2675 | |
2676 htab_delete (repl_tbl); | |
2677 repl_tbl = NULL; | |
2678 | |
2679 need_to_initialize_update_ssa_p = true; | |
2680 need_to_update_vops_p = false; | |
2681 BITMAP_FREE (syms_to_rename); | |
2682 BITMAP_FREE (regs_to_rename); | |
2683 BITMAP_FREE (mem_syms_to_rename); | |
2684 BITMAP_FREE (update_ssa_stats.virtual_symbols); | |
2685 | |
2686 if (names_to_release) | |
2687 { | |
2688 EXECUTE_IF_SET_IN_BITMAP (names_to_release, 0, i, bi) | |
2689 release_ssa_name (ssa_name (i)); | |
2690 BITMAP_FREE (names_to_release); | |
2691 } | |
2692 | |
2693 clear_ssa_name_info (); | |
2694 | |
2695 fini_ssa_renamer (); | |
2696 | |
2697 if (blocks_with_phis_to_rewrite) | |
2698 EXECUTE_IF_SET_IN_BITMAP (blocks_with_phis_to_rewrite, 0, i, bi) | |
2699 { | |
2700 gimple_vec phis = VEC_index (gimple_vec, phis_to_rewrite, i); | |
2701 | |
2702 VEC_free (gimple, heap, phis); | |
2703 VEC_replace (gimple_vec, phis_to_rewrite, i, NULL); | |
2704 } | |
2705 | |
2706 BITMAP_FREE (blocks_with_phis_to_rewrite); | |
2707 BITMAP_FREE (blocks_to_update); | |
2708 } | |
2709 | |
2710 | |
2711 /* Create a new name for OLD_NAME in statement STMT and replace the | |
2712 operand pointed to by DEF_P with the newly created name. Return | |
2713 the new name and register the replacement mapping <NEW, OLD> in | |
2714 update_ssa's tables. */ | |
2715 | |
2716 tree | |
2717 create_new_def_for (tree old_name, gimple stmt, def_operand_p def) | |
2718 { | |
2719 tree new_name = duplicate_ssa_name (old_name, stmt); | |
2720 | |
2721 SET_DEF (def, new_name); | |
2722 | |
2723 if (gimple_code (stmt) == GIMPLE_PHI) | |
2724 { | |
2725 edge e; | |
2726 edge_iterator ei; | |
2727 basic_block bb = gimple_bb (stmt); | |
2728 | |
2729 /* If needed, mark NEW_NAME as occurring in an abnormal PHI node. */ | |
2730 FOR_EACH_EDGE (e, ei, bb->preds) | |
2731 if (e->flags & EDGE_ABNORMAL) | |
2732 { | |
2733 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (new_name) = 1; | |
2734 break; | |
2735 } | |
2736 } | |
2737 | |
2738 register_new_name_mapping (new_name, old_name); | |
2739 | |
2740 /* For the benefit of passes that will be updating the SSA form on | |
2741 their own, set the current reaching definition of OLD_NAME to be | |
2742 NEW_NAME. */ | |
2743 set_current_def (old_name, new_name); | |
2744 | |
2745 return new_name; | |
2746 } | |
2747 | |
2748 | |
2749 /* Register name NEW to be a replacement for name OLD. This function | |
2750 must be called for every replacement that should be performed by | |
2751 update_ssa. */ | |
2752 | |
2753 void | |
2754 register_new_name_mapping (tree new_Tree ATTRIBUTE_UNUSED, tree old ATTRIBUTE_UNUSED) | |
2755 { | |
2756 if (need_to_initialize_update_ssa_p) | |
2757 init_update_ssa (); | |
2758 | |
2759 add_new_name_mapping (new_Tree, old); | |
2760 } | |
2761 | |
2762 | |
2763 /* Register symbol SYM to be renamed by update_ssa. */ | |
2764 | |
2765 void | |
2766 mark_sym_for_renaming (tree sym) | |
2767 { | |
2768 if (need_to_initialize_update_ssa_p) | |
2769 init_update_ssa (); | |
2770 | |
2771 bitmap_set_bit (syms_to_rename, DECL_UID (sym)); | |
2772 | |
2773 if (!is_gimple_reg (sym)) | |
2774 { | |
2775 need_to_update_vops_p = true; | |
2776 if (memory_partition (sym)) | |
2777 bitmap_set_bit (syms_to_rename, DECL_UID (memory_partition (sym))); | |
2778 } | |
2779 } | |
2780 | |
2781 | |
2782 /* Register all the symbols in SET to be renamed by update_ssa. */ | |
2783 | |
2784 void | |
2785 mark_set_for_renaming (bitmap set) | |
2786 { | |
2787 bitmap_iterator bi; | |
2788 unsigned i; | |
2789 | |
2790 if (set == NULL || bitmap_empty_p (set)) | |
2791 return; | |
2792 | |
2793 if (need_to_initialize_update_ssa_p) | |
2794 init_update_ssa (); | |
2795 | |
2796 EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi) | |
2797 mark_sym_for_renaming (referenced_var (i)); | |
2798 } | |
2799 | |
2800 | |
2801 /* Return true if there is any work to be done by update_ssa. */ | |
2802 | |
2803 bool | |
2804 need_ssa_update_p (void) | |
2805 { | |
2806 return syms_to_rename || old_ssa_names || new_ssa_names; | |
2807 } | |
2808 | |
2809 /* Return true if SSA name mappings have been registered for SSA updating. */ | |
2810 | |
2811 bool | |
2812 name_mappings_registered_p (void) | |
2813 { | |
2814 return repl_tbl && htab_elements (repl_tbl) > 0; | |
2815 } | |
2816 | |
2817 /* Return true if name N has been registered in the replacement table. */ | |
2818 | |
2819 bool | |
2820 name_registered_for_update_p (tree n ATTRIBUTE_UNUSED) | |
2821 { | |
2822 if (!need_ssa_update_p ()) | |
2823 return false; | |
2824 | |
2825 return is_new_name (n) | |
2826 || is_old_name (n) | |
2827 || symbol_marked_for_renaming (SSA_NAME_VAR (n)); | |
2828 } | |
2829 | |
2830 | |
2831 /* Return the set of all the SSA names marked to be replaced. */ | |
2832 | |
2833 bitmap | |
2834 ssa_names_to_replace (void) | |
2835 { | |
2836 unsigned i = 0; | |
2837 bitmap ret; | |
2838 sbitmap_iterator sbi; | |
2839 | |
2840 ret = BITMAP_ALLOC (NULL); | |
2841 EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi) | |
2842 bitmap_set_bit (ret, i); | |
2843 | |
2844 return ret; | |
2845 } | |
2846 | |
2847 | |
2848 /* Mark NAME to be released after update_ssa has finished. */ | |
2849 | |
2850 void | |
2851 release_ssa_name_after_update_ssa (tree name) | |
2852 { | |
2853 gcc_assert (!need_to_initialize_update_ssa_p); | |
2854 | |
2855 if (names_to_release == NULL) | |
2856 names_to_release = BITMAP_ALLOC (NULL); | |
2857 | |
2858 bitmap_set_bit (names_to_release, SSA_NAME_VERSION (name)); | |
2859 } | |
2860 | |
2861 | |
2862 /* Insert new PHI nodes to replace VAR. DFS contains dominance | |
2863 frontier information. BLOCKS is the set of blocks to be updated. | |
2864 | |
2865 This is slightly different than the regular PHI insertion | |
2866 algorithm. The value of UPDATE_FLAGS controls how PHI nodes for | |
2867 real names (i.e., GIMPLE registers) are inserted: | |
2868 | |
2869 - If UPDATE_FLAGS == TODO_update_ssa, we are only interested in PHI | |
2870 nodes inside the region affected by the block that defines VAR | |
2871 and the blocks that define all its replacements. All these | |
2872 definition blocks are stored in DEF_BLOCKS[VAR]->DEF_BLOCKS. | |
2873 | |
2874 First, we compute the entry point to the region (ENTRY). This is | |
2875 given by the nearest common dominator to all the definition | |
2876 blocks. When computing the iterated dominance frontier (IDF), any | |
2877 block not strictly dominated by ENTRY is ignored. | |
2878 | |
2879 We then call the standard PHI insertion algorithm with the pruned | |
2880 IDF. | |
2881 | |
2882 - If UPDATE_FLAGS == TODO_update_ssa_full_phi, the IDF for real | |
2883 names is not pruned. PHI nodes are inserted at every IDF block. */ | |
2884 | |
2885 static void | |
2886 insert_updated_phi_nodes_for (tree var, bitmap *dfs, bitmap blocks, | |
2887 unsigned update_flags) | |
2888 { | |
2889 basic_block entry; | |
2890 struct def_blocks_d *db; | |
2891 bitmap idf, pruned_idf; | |
2892 bitmap_iterator bi; | |
2893 unsigned i; | |
2894 | |
2895 #if defined ENABLE_CHECKING | |
2896 if (TREE_CODE (var) == SSA_NAME) | |
2897 gcc_assert (is_old_name (var)); | |
2898 else | |
2899 gcc_assert (symbol_marked_for_renaming (var)); | |
2900 #endif | |
2901 | |
2902 /* Get all the definition sites for VAR. */ | |
2903 db = find_def_blocks_for (var); | |
2904 | |
2905 /* No need to do anything if there were no definitions to VAR. */ | |
2906 if (db == NULL || bitmap_empty_p (db->def_blocks)) | |
2907 return; | |
2908 | |
2909 /* Compute the initial iterated dominance frontier. */ | |
2910 idf = compute_idf (db->def_blocks, dfs); | |
2911 pruned_idf = BITMAP_ALLOC (NULL); | |
2912 | |
2913 if (TREE_CODE (var) == SSA_NAME) | |
2914 { | |
2915 if (update_flags == TODO_update_ssa) | |
2916 { | |
2917 /* If doing regular SSA updates for GIMPLE registers, we are | |
2918 only interested in IDF blocks dominated by the nearest | |
2919 common dominator of all the definition blocks. */ | |
2920 entry = nearest_common_dominator_for_set (CDI_DOMINATORS, | |
2921 db->def_blocks); | |
2922 if (entry != ENTRY_BLOCK_PTR) | |
2923 EXECUTE_IF_SET_IN_BITMAP (idf, 0, i, bi) | |
2924 if (BASIC_BLOCK (i) != entry | |
2925 && dominated_by_p (CDI_DOMINATORS, BASIC_BLOCK (i), entry)) | |
2926 bitmap_set_bit (pruned_idf, i); | |
2927 } | |
2928 else | |
2929 { | |
2930 /* Otherwise, do not prune the IDF for VAR. */ | |
2931 gcc_assert (update_flags == TODO_update_ssa_full_phi); | |
2932 bitmap_copy (pruned_idf, idf); | |
2933 } | |
2934 } | |
2935 else | |
2936 { | |
2937 /* Otherwise, VAR is a symbol that needs to be put into SSA form | |
2938 for the first time, so we need to compute the full IDF for | |
2939 it. */ | |
2940 bitmap_copy (pruned_idf, idf); | |
2941 } | |
2942 | |
2943 if (!bitmap_empty_p (pruned_idf)) | |
2944 { | |
2945 /* Make sure that PRUNED_IDF blocks and all their feeding blocks | |
2946 are included in the region to be updated. The feeding blocks | |
2947 are important to guarantee that the PHI arguments are renamed | |
2948 properly. */ | |
2949 | |
2950 /* FIXME, this is not needed if we are updating symbols. We are | |
2951 already starting at the ENTRY block anyway. */ | |
2952 bitmap_ior_into (blocks, pruned_idf); | |
2953 EXECUTE_IF_SET_IN_BITMAP (pruned_idf, 0, i, bi) | |
2954 { | |
2955 edge e; | |
2956 edge_iterator ei; | |
2957 basic_block bb = BASIC_BLOCK (i); | |
2958 | |
2959 FOR_EACH_EDGE (e, ei, bb->preds) | |
2960 if (e->src->index >= 0) | |
2961 bitmap_set_bit (blocks, e->src->index); | |
2962 } | |
2963 | |
2964 insert_phi_nodes_for (var, pruned_idf, true); | |
2965 } | |
2966 | |
2967 BITMAP_FREE (pruned_idf); | |
2968 BITMAP_FREE (idf); | |
2969 } | |
2970 | |
2971 | |
2972 /* Heuristic to determine whether SSA name mappings for virtual names | |
2973 should be discarded and their symbols rewritten from scratch. When | |
2974 there is a large number of mappings for virtual names, the | |
2975 insertion of PHI nodes for the old names in the mappings takes | |
2976 considerable more time than if we inserted PHI nodes for the | |
2977 symbols instead. | |
2978 | |
2979 Currently the heuristic takes these stats into account: | |
2980 | |
2981 - Number of mappings for virtual SSA names. | |
2982 - Number of distinct virtual symbols involved in those mappings. | |
2983 | |
2984 If the number of virtual mappings is much larger than the number of | |
2985 virtual symbols, then it will be faster to compute PHI insertion | |
2986 spots for the symbols. Even if this involves traversing the whole | |
2987 CFG, which is what happens when symbols are renamed from scratch. */ | |
2988 | |
2989 static bool | |
2990 switch_virtuals_to_full_rewrite_p (void) | |
2991 { | |
2992 if (update_ssa_stats.num_virtual_mappings < (unsigned) MIN_VIRTUAL_MAPPINGS) | |
2993 return false; | |
2994 | |
2995 if (update_ssa_stats.num_virtual_mappings | |
2996 > (unsigned) VIRTUAL_MAPPINGS_TO_SYMS_RATIO | |
2997 * update_ssa_stats.num_virtual_symbols) | |
2998 return true; | |
2999 | |
3000 return false; | |
3001 } | |
3002 | |
3003 | |
3004 /* Remove every virtual mapping and mark all the affected virtual | |
3005 symbols for renaming. */ | |
3006 | |
3007 static void | |
3008 switch_virtuals_to_full_rewrite (void) | |
3009 { | |
3010 unsigned i = 0; | |
3011 sbitmap_iterator sbi; | |
3012 | |
3013 if (dump_file) | |
3014 { | |
3015 fprintf (dump_file, "\nEnabled virtual name mapping heuristic.\n"); | |
3016 fprintf (dump_file, "\tNumber of virtual mappings: %7u\n", | |
3017 update_ssa_stats.num_virtual_mappings); | |
3018 fprintf (dump_file, "\tNumber of unique virtual symbols: %7u\n", | |
3019 update_ssa_stats.num_virtual_symbols); | |
3020 fprintf (dump_file, "Updating FUD-chains from top of CFG will be " | |
3021 "faster than processing\nthe name mappings.\n\n"); | |
3022 } | |
3023 | |
3024 /* Remove all virtual names from NEW_SSA_NAMES and OLD_SSA_NAMES. | |
3025 Note that it is not really necessary to remove the mappings from | |
3026 REPL_TBL, that would only waste time. */ | |
3027 EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi) | |
3028 if (!is_gimple_reg (ssa_name (i))) | |
3029 RESET_BIT (new_ssa_names, i); | |
3030 | |
3031 EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi) | |
3032 if (!is_gimple_reg (ssa_name (i))) | |
3033 RESET_BIT (old_ssa_names, i); | |
3034 | |
3035 mark_set_for_renaming (update_ssa_stats.virtual_symbols); | |
3036 } | |
3037 | |
3038 | |
3039 /* Given a set of newly created SSA names (NEW_SSA_NAMES) and a set of | |
3040 existing SSA names (OLD_SSA_NAMES), update the SSA form so that: | |
3041 | |
3042 1- The names in OLD_SSA_NAMES dominated by the definitions of | |
3043 NEW_SSA_NAMES are all re-written to be reached by the | |
3044 appropriate definition from NEW_SSA_NAMES. | |
3045 | |
3046 2- If needed, new PHI nodes are added to the iterated dominance | |
3047 frontier of the blocks where each of NEW_SSA_NAMES are defined. | |
3048 | |
3049 The mapping between OLD_SSA_NAMES and NEW_SSA_NAMES is setup by | |
3050 calling register_new_name_mapping for every pair of names that the | |
3051 caller wants to replace. | |
3052 | |
3053 The caller identifies the new names that have been inserted and the | |
3054 names that need to be replaced by calling register_new_name_mapping | |
3055 for every pair <NEW, OLD>. Note that the function assumes that the | |
3056 new names have already been inserted in the IL. | |
3057 | |
3058 For instance, given the following code: | |
3059 | |
3060 1 L0: | |
3061 2 x_1 = PHI (0, x_5) | |
3062 3 if (x_1 < 10) | |
3063 4 if (x_1 > 7) | |
3064 5 y_2 = 0 | |
3065 6 else | |
3066 7 y_3 = x_1 + x_7 | |
3067 8 endif | |
3068 9 x_5 = x_1 + 1 | |
3069 10 goto L0; | |
3070 11 endif | |
3071 | |
3072 Suppose that we insert new names x_10 and x_11 (lines 4 and 8). | |
3073 | |
3074 1 L0: | |
3075 2 x_1 = PHI (0, x_5) | |
3076 3 if (x_1 < 10) | |
3077 4 x_10 = ... | |
3078 5 if (x_1 > 7) | |
3079 6 y_2 = 0 | |
3080 7 else | |
3081 8 x_11 = ... | |
3082 9 y_3 = x_1 + x_7 | |
3083 10 endif | |
3084 11 x_5 = x_1 + 1 | |
3085 12 goto L0; | |
3086 13 endif | |
3087 | |
3088 We want to replace all the uses of x_1 with the new definitions of | |
3089 x_10 and x_11. Note that the only uses that should be replaced are | |
3090 those at lines 5, 9 and 11. Also, the use of x_7 at line 9 should | |
3091 *not* be replaced (this is why we cannot just mark symbol 'x' for | |
3092 renaming). | |
3093 | |
3094 Additionally, we may need to insert a PHI node at line 11 because | |
3095 that is a merge point for x_10 and x_11. So the use of x_1 at line | |
3096 11 will be replaced with the new PHI node. The insertion of PHI | |
3097 nodes is optional. They are not strictly necessary to preserve the | |
3098 SSA form, and depending on what the caller inserted, they may not | |
3099 even be useful for the optimizers. UPDATE_FLAGS controls various | |
3100 aspects of how update_ssa operates, see the documentation for | |
3101 TODO_update_ssa*. */ | |
3102 | |
3103 void | |
3104 update_ssa (unsigned update_flags) | |
3105 { | |
3106 basic_block bb, start_bb; | |
3107 bitmap_iterator bi; | |
3108 unsigned i = 0; | |
3109 sbitmap tmp; | |
3110 bool insert_phi_p; | |
3111 sbitmap_iterator sbi; | |
3112 | |
3113 if (!need_ssa_update_p ()) | |
3114 return; | |
3115 | |
3116 timevar_push (TV_TREE_SSA_INCREMENTAL); | |
3117 | |
3118 blocks_with_phis_to_rewrite = BITMAP_ALLOC (NULL); | |
3119 if (!phis_to_rewrite) | |
3120 phis_to_rewrite = VEC_alloc (gimple_vec, heap, last_basic_block); | |
3121 blocks_to_update = BITMAP_ALLOC (NULL); | |
3122 | |
3123 /* Ensure that the dominance information is up-to-date. */ | |
3124 calculate_dominance_info (CDI_DOMINATORS); | |
3125 | |
3126 /* Only one update flag should be set. */ | |
3127 gcc_assert (update_flags == TODO_update_ssa | |
3128 || update_flags == TODO_update_ssa_no_phi | |
3129 || update_flags == TODO_update_ssa_full_phi | |
3130 || update_flags == TODO_update_ssa_only_virtuals); | |
3131 | |
3132 /* If we only need to update virtuals, remove all the mappings for | |
3133 real names before proceeding. The caller is responsible for | |
3134 having dealt with the name mappings before calling update_ssa. */ | |
3135 if (update_flags == TODO_update_ssa_only_virtuals) | |
3136 { | |
3137 sbitmap_zero (old_ssa_names); | |
3138 sbitmap_zero (new_ssa_names); | |
3139 htab_empty (repl_tbl); | |
3140 } | |
3141 | |
3142 insert_phi_p = (update_flags != TODO_update_ssa_no_phi); | |
3143 | |
3144 if (insert_phi_p) | |
3145 { | |
3146 /* If the caller requested PHI nodes to be added, initialize | |
3147 live-in information data structures (DEF_BLOCKS). */ | |
3148 | |
3149 /* For each SSA name N, the DEF_BLOCKS table describes where the | |
3150 name is defined, which blocks have PHI nodes for N, and which | |
3151 blocks have uses of N (i.e., N is live-on-entry in those | |
3152 blocks). */ | |
3153 def_blocks = htab_create (num_ssa_names, def_blocks_hash, | |
3154 def_blocks_eq, def_blocks_free); | |
3155 } | |
3156 else | |
3157 { | |
3158 def_blocks = NULL; | |
3159 } | |
3160 | |
3161 /* Heuristic to avoid massive slow downs when the replacement | |
3162 mappings include lots of virtual names. */ | |
3163 if (insert_phi_p && switch_virtuals_to_full_rewrite_p ()) | |
3164 switch_virtuals_to_full_rewrite (); | |
3165 | |
3166 /* If there are symbols to rename, identify those symbols that are | |
3167 GIMPLE registers into the set REGS_TO_RENAME and those that are | |
3168 memory symbols into the set MEM_SYMS_TO_RENAME. */ | |
3169 if (!bitmap_empty_p (syms_to_rename)) | |
3170 { | |
3171 unsigned i; | |
3172 bitmap_iterator bi; | |
3173 | |
3174 EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi) | |
3175 { | |
3176 tree sym = referenced_var (i); | |
3177 if (is_gimple_reg (sym)) | |
3178 bitmap_set_bit (regs_to_rename, i); | |
3179 else | |
3180 { | |
3181 /* Memory partitioning information may have been | |
3182 computed after the symbol was marked for renaming, | |
3183 if SYM is inside a partition also mark the partition | |
3184 for renaming. */ | |
3185 tree mpt = memory_partition (sym); | |
3186 if (mpt) | |
3187 bitmap_set_bit (syms_to_rename, DECL_UID (mpt)); | |
3188 } | |
3189 } | |
3190 | |
3191 /* Memory symbols are those not in REGS_TO_RENAME. */ | |
3192 bitmap_and_compl (mem_syms_to_rename, syms_to_rename, regs_to_rename); | |
3193 } | |
3194 | |
3195 /* If there are names defined in the replacement table, prepare | |
3196 definition and use sites for all the names in NEW_SSA_NAMES and | |
3197 OLD_SSA_NAMES. */ | |
3198 if (sbitmap_first_set_bit (new_ssa_names) >= 0) | |
3199 { | |
3200 prepare_names_to_update (insert_phi_p); | |
3201 | |
3202 /* If all the names in NEW_SSA_NAMES had been marked for | |
3203 removal, and there are no symbols to rename, then there's | |
3204 nothing else to do. */ | |
3205 if (sbitmap_first_set_bit (new_ssa_names) < 0 | |
3206 && bitmap_empty_p (syms_to_rename)) | |
3207 goto done; | |
3208 } | |
3209 | |
3210 /* Next, determine the block at which to start the renaming process. */ | |
3211 if (!bitmap_empty_p (syms_to_rename)) | |
3212 { | |
3213 /* If we have to rename some symbols from scratch, we need to | |
3214 start the process at the root of the CFG. FIXME, it should | |
3215 be possible to determine the nearest block that had a | |
3216 definition for each of the symbols that are marked for | |
3217 updating. For now this seems more work than it's worth. */ | |
3218 start_bb = ENTRY_BLOCK_PTR; | |
3219 | |
3220 /* Traverse the CFG looking for existing definitions and uses of | |
3221 symbols in SYMS_TO_RENAME. Mark interesting blocks and | |
3222 statements and set local live-in information for the PHI | |
3223 placement heuristics. */ | |
3224 prepare_block_for_update (start_bb, insert_phi_p); | |
3225 } | |
3226 else | |
3227 { | |
3228 /* Otherwise, the entry block to the region is the nearest | |
3229 common dominator for the blocks in BLOCKS. */ | |
3230 start_bb = nearest_common_dominator_for_set (CDI_DOMINATORS, | |
3231 blocks_to_update); | |
3232 } | |
3233 | |
3234 /* If requested, insert PHI nodes at the iterated dominance frontier | |
3235 of every block, creating new definitions for names in OLD_SSA_NAMES | |
3236 and for symbols in SYMS_TO_RENAME. */ | |
3237 if (insert_phi_p) | |
3238 { | |
3239 bitmap *dfs; | |
3240 | |
3241 /* If the caller requested PHI nodes to be added, compute | |
3242 dominance frontiers. */ | |
3243 dfs = XNEWVEC (bitmap, last_basic_block); | |
3244 FOR_EACH_BB (bb) | |
3245 dfs[bb->index] = BITMAP_ALLOC (NULL); | |
3246 compute_dominance_frontiers (dfs); | |
3247 | |
3248 if (sbitmap_first_set_bit (old_ssa_names) >= 0) | |
3249 { | |
3250 sbitmap_iterator sbi; | |
3251 | |
3252 /* insert_update_phi_nodes_for will call add_new_name_mapping | |
3253 when inserting new PHI nodes, so the set OLD_SSA_NAMES | |
3254 will grow while we are traversing it (but it will not | |
3255 gain any new members). Copy OLD_SSA_NAMES to a temporary | |
3256 for traversal. */ | |
3257 sbitmap tmp = sbitmap_alloc (old_ssa_names->n_bits); | |
3258 sbitmap_copy (tmp, old_ssa_names); | |
3259 EXECUTE_IF_SET_IN_SBITMAP (tmp, 0, i, sbi) | |
3260 insert_updated_phi_nodes_for (ssa_name (i), dfs, blocks_to_update, | |
3261 update_flags); | |
3262 sbitmap_free (tmp); | |
3263 } | |
3264 | |
3265 EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi) | |
3266 insert_updated_phi_nodes_for (referenced_var (i), dfs, blocks_to_update, | |
3267 update_flags); | |
3268 | |
3269 FOR_EACH_BB (bb) | |
3270 BITMAP_FREE (dfs[bb->index]); | |
3271 free (dfs); | |
3272 | |
3273 /* Insertion of PHI nodes may have added blocks to the region. | |
3274 We need to re-compute START_BB to include the newly added | |
3275 blocks. */ | |
3276 if (start_bb != ENTRY_BLOCK_PTR) | |
3277 start_bb = nearest_common_dominator_for_set (CDI_DOMINATORS, | |
3278 blocks_to_update); | |
3279 } | |
3280 | |
3281 /* Reset the current definition for name and symbol before renaming | |
3282 the sub-graph. */ | |
3283 EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi) | |
3284 set_current_def (ssa_name (i), NULL_TREE); | |
3285 | |
3286 EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi) | |
3287 set_current_def (referenced_var (i), NULL_TREE); | |
3288 | |
3289 /* Now start the renaming process at START_BB. */ | |
3290 tmp = sbitmap_alloc (last_basic_block); | |
3291 sbitmap_zero (tmp); | |
3292 EXECUTE_IF_SET_IN_BITMAP (blocks_to_update, 0, i, bi) | |
3293 SET_BIT (tmp, i); | |
3294 | |
3295 rewrite_blocks (start_bb, REWRITE_UPDATE, tmp); | |
3296 | |
3297 sbitmap_free (tmp); | |
3298 | |
3299 /* Debugging dumps. */ | |
3300 if (dump_file) | |
3301 { | |
3302 int c; | |
3303 unsigned i; | |
3304 | |
3305 dump_update_ssa (dump_file); | |
3306 | |
3307 fprintf (dump_file, "Incremental SSA update started at block: %d\n\n", | |
3308 start_bb->index); | |
3309 | |
3310 c = 0; | |
3311 EXECUTE_IF_SET_IN_BITMAP (blocks_to_update, 0, i, bi) | |
3312 c++; | |
3313 fprintf (dump_file, "Number of blocks in CFG: %d\n", last_basic_block); | |
3314 fprintf (dump_file, "Number of blocks to update: %d (%3.0f%%)\n\n", | |
3315 c, PERCENT (c, last_basic_block)); | |
3316 | |
3317 if (dump_flags & TDF_DETAILS) | |
3318 { | |
3319 fprintf (dump_file, "Affected blocks: "); | |
3320 EXECUTE_IF_SET_IN_BITMAP (blocks_to_update, 0, i, bi) | |
3321 fprintf (dump_file, "%u ", i); | |
3322 fprintf (dump_file, "\n"); | |
3323 } | |
3324 | |
3325 fprintf (dump_file, "\n\n"); | |
3326 } | |
3327 | |
3328 /* Free allocated memory. */ | |
3329 done: | |
3330 delete_update_ssa (); | |
3331 | |
3332 timevar_pop (TV_TREE_SSA_INCREMENTAL); | |
3333 } |