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1 : : /* Generic SSA value propagation engine.
2 : : Copyright (C) 2004-2025 Free Software Foundation, Inc.
3 : : Contributed by Diego Novillo <dnovillo@redhat.com>
4 : :
5 : : This file is part of GCC.
6 : :
7 : : GCC is free software; you can redistribute it and/or modify it
8 : : under the terms of the GNU General Public License as published by the
9 : : Free Software Foundation; either version 3, or (at your option) any
10 : : later version.
11 : :
12 : : GCC is distributed in the hope that it will be useful, but WITHOUT
13 : : ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 : : FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 : : for more details.
16 : :
17 : : You should have received a copy of the GNU General Public License
18 : : along with GCC; see the file COPYING3. If not see
19 : : <http://www.gnu.org/licenses/>. */
20 : :
21 : : #include "config.h"
22 : : #include "system.h"
23 : : #include "coretypes.h"
24 : : #include "backend.h"
25 : : #include "tree.h"
26 : : #include "gimple.h"
27 : : #include "ssa.h"
28 : : #include "gimple-pretty-print.h"
29 : : #include "dumpfile.h"
30 : : #include "gimple-iterator.h"
31 : : #include "gimple-fold.h"
32 : : #include "tree-eh.h"
33 : : #include "gimplify.h"
34 : : #include "tree-cfg.h"
35 : : #include "tree-ssa.h"
36 : : #include "tree-ssa-propagate.h"
37 : : #include "domwalk.h"
38 : : #include "cfgloop.h"
39 : : #include "tree-cfgcleanup.h"
40 : : #include "cfganal.h"
41 : : #include "tree-ssa-dce.h"
42 : :
43 : : /* This file implements a generic value propagation engine based on
44 : : the same propagation used by the SSA-CCP algorithm [1].
45 : :
46 : : Propagation is performed by simulating the execution of every
47 : : statement that produces the value being propagated. Simulation
48 : : proceeds as follows:
49 : :
50 : : 1- Initially, all edges of the CFG are marked not executable and
51 : : the CFG worklist is seeded with all the statements in the entry
52 : : basic block (block 0).
53 : :
54 : : 2- Every statement S is simulated with a call to the call-back
55 : : function SSA_PROP_VISIT_STMT. This evaluation may produce 3
56 : : results:
57 : :
58 : : SSA_PROP_NOT_INTERESTING: Statement S produces nothing of
59 : : interest and does not affect any of the work lists.
60 : : The statement may be simulated again if any of its input
61 : : operands change in future iterations of the simulator.
62 : :
63 : : SSA_PROP_VARYING: The value produced by S cannot be determined
64 : : at compile time. Further simulation of S is not required.
65 : : If S is a conditional jump, all the outgoing edges for the
66 : : block are considered executable and added to the work
67 : : list.
68 : :
69 : : SSA_PROP_INTERESTING: S produces a value that can be computed
70 : : at compile time. Its result can be propagated into the
71 : : statements that feed from S. Furthermore, if S is a
72 : : conditional jump, only the edge known to be taken is added
73 : : to the work list. Edges that are known not to execute are
74 : : never simulated.
75 : :
76 : : 3- PHI nodes are simulated with a call to SSA_PROP_VISIT_PHI. The
77 : : return value from SSA_PROP_VISIT_PHI has the same semantics as
78 : : described in #2.
79 : :
80 : : 4- Three work lists are kept. Statements are only added to these
81 : : lists if they produce one of SSA_PROP_INTERESTING or
82 : : SSA_PROP_VARYING.
83 : :
84 : : CFG_BLOCKS contains the list of blocks to be simulated.
85 : : Blocks are added to this list if their incoming edges are
86 : : found executable.
87 : :
88 : : SSA_EDGE_WORKLIST contains the list of statements that we
89 : : need to revisit.
90 : :
91 : : 5- Simulation terminates when all three work lists are drained.
92 : :
93 : : Before calling ssa_propagate, it is important to clear
94 : : prop_simulate_again_p for all the statements in the program that
95 : : should be simulated. This initialization allows an implementation
96 : : to specify which statements should never be simulated.
97 : :
98 : : It is also important to compute def-use information before calling
99 : : ssa_propagate.
100 : :
101 : : References:
102 : :
103 : : [1] Constant propagation with conditional branches,
104 : : Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
105 : :
106 : : [2] Building an Optimizing Compiler,
107 : : Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
108 : :
109 : : [3] Advanced Compiler Design and Implementation,
110 : : Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */
111 : :
112 : : /* Worklists of control flow edge destinations. This contains
113 : : the CFG order number of the blocks so we can iterate in CFG
114 : : order by visiting in bit-order. We use two worklists to
115 : : first make forward progress before iterating. */
116 : : static bitmap cfg_blocks;
117 : : static int *bb_to_cfg_order;
118 : : static int *cfg_order_to_bb;
119 : :
120 : : /* Worklists of SSA edges which will need reexamination as their
121 : : definition has changed. SSA edges are def-use edges in the SSA
122 : : web. For each D-U edge, we store the target statement or PHI node
123 : : UID in a bitmap. UIDs order stmts in execution order. We use
124 : : two worklists to first make forward progress before iterating. */
125 : : static bitmap ssa_edge_worklist;
126 : : static vec<gimple *> uid_to_stmt;
127 : :
128 : : /* Current RPO index in the iteration. */
129 : : static int curr_order;
130 : :
131 : :
132 : : /* We have just defined a new value for VAR. If IS_VARYING is true,
133 : : add all immediate uses of VAR to VARYING_SSA_EDGES, otherwise add
134 : : them to INTERESTING_SSA_EDGES. */
135 : :
136 : : static void
137 : 280679800 : add_ssa_edge (tree var)
138 : : {
139 : 280679800 : imm_use_iterator iter;
140 : 280679800 : use_operand_p use_p;
141 : :
142 : 856720024 : FOR_EACH_IMM_USE_FAST (use_p, iter, var)
143 : : {
144 : 576040224 : gimple *use_stmt = USE_STMT (use_p);
145 : 576040224 : if (!prop_simulate_again_p (use_stmt))
146 : 242404814 : continue;
147 : :
148 : : /* If we did not yet simulate the block wait for this to happen
149 : : and do not add the stmt to the SSA edge worklist. */
150 : 333635410 : basic_block use_bb = gimple_bb (use_stmt);
151 : 333635410 : if (! (use_bb->flags & BB_VISITED))
152 : 137946853 : continue;
153 : :
154 : : /* If this is a use on a not yet executable edge do not bother to
155 : : queue it. */
156 : 195688557 : if (gimple_code (use_stmt) == GIMPLE_PHI
157 : 195688557 : && !(EDGE_PRED (use_bb, PHI_ARG_INDEX_FROM_USE (use_p))->flags
158 : 64345673 : & EDGE_EXECUTABLE))
159 : 5936559 : continue;
160 : :
161 : 189751998 : if (bitmap_set_bit (ssa_edge_worklist, gimple_uid (use_stmt)))
162 : : {
163 : 175618380 : uid_to_stmt[gimple_uid (use_stmt)] = use_stmt;
164 : 175618380 : if (dump_file && (dump_flags & TDF_DETAILS))
165 : : {
166 : 0 : fprintf (dump_file, "ssa_edge_worklist: adding SSA use in ");
167 : 0 : print_gimple_stmt (dump_file, use_stmt, 0, TDF_SLIM);
168 : : }
169 : : }
170 : : }
171 : 280679800 : }
172 : :
173 : :
174 : : /* Add edge E to the control flow worklist. */
175 : :
176 : : static void
177 : 138370787 : add_control_edge (edge e)
178 : : {
179 : 138370787 : basic_block bb = e->dest;
180 : 138370787 : if (bb == EXIT_BLOCK_PTR_FOR_FN (cfun))
181 : : return;
182 : :
183 : : /* If the edge had already been executed, skip it. */
184 : 122917493 : if (e->flags & EDGE_EXECUTABLE)
185 : : return;
186 : :
187 : 105945748 : e->flags |= EDGE_EXECUTABLE;
188 : :
189 : 105945748 : int bb_order = bb_to_cfg_order[bb->index];
190 : 105945748 : bitmap_set_bit (cfg_blocks, bb_order);
191 : :
192 : 105945748 : if (dump_file && (dump_flags & TDF_DETAILS))
193 : 61 : fprintf (dump_file, "Adding destination of edge (%d -> %d) to worklist\n",
194 : 61 : e->src->index, e->dest->index);
195 : : }
196 : :
197 : :
198 : : /* Simulate the execution of STMT and update the work lists accordingly. */
199 : :
200 : : void
201 : 786670253 : ssa_propagation_engine::simulate_stmt (gimple *stmt)
202 : : {
203 : 786670253 : enum ssa_prop_result val = SSA_PROP_NOT_INTERESTING;
204 : 786670253 : edge taken_edge = NULL;
205 : 786670253 : tree output_name = NULL_TREE;
206 : :
207 : : /* Pull the stmt off the SSA edge worklist. */
208 : 786670253 : bitmap_clear_bit (ssa_edge_worklist, gimple_uid (stmt));
209 : :
210 : : /* Don't bother visiting statements that are already
211 : : considered varying by the propagator. */
212 : 786670253 : if (!prop_simulate_again_p (stmt))
213 : 555784052 : return;
214 : :
215 : 352503927 : if (gimple_code (stmt) == GIMPLE_PHI)
216 : : {
217 : 79575712 : val = visit_phi (as_a <gphi *> (stmt));
218 : 79575712 : output_name = gimple_phi_result (stmt);
219 : : }
220 : : else
221 : 272928215 : val = visit_stmt (stmt, &taken_edge, &output_name);
222 : :
223 : 352503927 : if (val == SSA_PROP_VARYING)
224 : : {
225 : 121617726 : prop_set_simulate_again (stmt, false);
226 : :
227 : : /* If the statement produced a new varying value, add the SSA
228 : : edges coming out of OUTPUT_NAME. */
229 : 121617726 : if (output_name)
230 : 72914850 : add_ssa_edge (output_name);
231 : :
232 : : /* If STMT transfers control out of its basic block, add
233 : : all outgoing edges to the work list. */
234 : 121617726 : if (stmt_ends_bb_p (stmt))
235 : : {
236 : 50188198 : edge e;
237 : 50188198 : edge_iterator ei;
238 : 50188198 : basic_block bb = gimple_bb (stmt);
239 : 129619907 : FOR_EACH_EDGE (e, ei, bb->succs)
240 : 79431709 : add_control_edge (e);
241 : : }
242 : 121617726 : return;
243 : : }
244 : 230886201 : else if (val == SSA_PROP_INTERESTING)
245 : : {
246 : : /* If the statement produced new value, add the SSA edges coming
247 : : out of OUTPUT_NAME. */
248 : 214278784 : if (output_name)
249 : 207764950 : add_ssa_edge (output_name);
250 : :
251 : : /* If we know which edge is going to be taken out of this block,
252 : : add it to the CFG work list. */
253 : 214278784 : if (taken_edge)
254 : 6513834 : add_control_edge (taken_edge);
255 : : }
256 : :
257 : : /* If there are no SSA uses on the stmt whose defs are simulated
258 : : again then this stmt will be never visited again. */
259 : 230886201 : bool has_simulate_again_uses = false;
260 : 230886201 : use_operand_p use_p;
261 : 230886201 : ssa_op_iter iter;
262 : 230886201 : if (gimple_code (stmt) == GIMPLE_PHI)
263 : : {
264 : 65879990 : edge_iterator ei;
265 : 65879990 : edge e;
266 : 65879990 : tree arg;
267 : 102495422 : FOR_EACH_EDGE (e, ei, gimple_bb (stmt)->preds)
268 : 100315266 : if (!(e->flags & EDGE_EXECUTABLE)
269 : 100315266 : || ((arg = PHI_ARG_DEF_FROM_EDGE (stmt, e))
270 : 92204846 : && TREE_CODE (arg) == SSA_NAME
271 : 75757413 : && !SSA_NAME_IS_DEFAULT_DEF (arg)
272 : 75541629 : && prop_simulate_again_p (SSA_NAME_DEF_STMT (arg))))
273 : : {
274 : : has_simulate_again_uses = true;
275 : : break;
276 : : }
277 : : }
278 : : else
279 : 203144174 : FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
280 : : {
281 : 163608393 : gimple *def_stmt = SSA_NAME_DEF_STMT (USE_FROM_PTR (use_p));
282 : 163608393 : if (!gimple_nop_p (def_stmt)
283 : 163608393 : && prop_simulate_again_p (def_stmt))
284 : : {
285 : : has_simulate_again_uses = true;
286 : : break;
287 : : }
288 : : }
289 : 230886201 : if (!has_simulate_again_uses)
290 : : {
291 : 41715937 : if (dump_file && (dump_flags & TDF_DETAILS))
292 : 40 : fprintf (dump_file, "marking stmt to be not simulated again\n");
293 : 41715937 : prop_set_simulate_again (stmt, false);
294 : : }
295 : : }
296 : :
297 : :
298 : : /* Simulate the execution of BLOCK. Evaluate the statement associated
299 : : with each variable reference inside the block. */
300 : :
301 : : void
302 : 80642888 : ssa_propagation_engine::simulate_block (basic_block block)
303 : : {
304 : 80642888 : gimple_stmt_iterator gsi;
305 : :
306 : : /* There is nothing to do for the exit block. */
307 : 80642888 : if (block == EXIT_BLOCK_PTR_FOR_FN (cfun))
308 : 80642888 : return;
309 : :
310 : 80642888 : if (dump_file && (dump_flags & TDF_DETAILS))
311 : 57 : fprintf (dump_file, "\nSimulating block %d\n", block->index);
312 : :
313 : : /* Always simulate PHI nodes, even if we have simulated this block
314 : : before. */
315 : 123824716 : for (gsi = gsi_start_phis (block); !gsi_end_p (gsi); gsi_next (&gsi))
316 : 43181828 : simulate_stmt (gsi_stmt (gsi));
317 : :
318 : : /* If this is the first time we've simulated this block, then we
319 : : must simulate each of its statements. */
320 : 80642888 : if (! (block->flags & BB_VISITED))
321 : : {
322 : 75425551 : gimple_stmt_iterator j;
323 : 75425551 : unsigned int normal_edge_count;
324 : 75425551 : edge e, normal_edge;
325 : 75425551 : edge_iterator ei;
326 : :
327 : 718832646 : for (j = gsi_start_bb (block); !gsi_end_p (j); gsi_next (&j))
328 : 567981544 : simulate_stmt (gsi_stmt (j));
329 : :
330 : : /* Note that we have simulated this block. */
331 : 75425551 : block->flags |= BB_VISITED;
332 : :
333 : : /* We cannot predict when abnormal and EH edges will be executed, so
334 : : once a block is considered executable, we consider any
335 : : outgoing abnormal edges as executable.
336 : :
337 : : TODO: This is not exactly true. Simplifying statement might
338 : : prove it non-throwing and also computed goto can be handled
339 : : when destination is known.
340 : :
341 : : At the same time, if this block has only one successor that is
342 : : reached by non-abnormal edges, then add that successor to the
343 : : worklist. */
344 : 75425551 : normal_edge_count = 0;
345 : 75425551 : normal_edge = NULL;
346 : 181606280 : FOR_EACH_EDGE (e, ei, block->succs)
347 : : {
348 : 106180729 : if (e->flags & (EDGE_ABNORMAL | EDGE_EH))
349 : 7231608 : add_control_edge (e);
350 : : else
351 : : {
352 : 98949121 : normal_edge_count++;
353 : 98949121 : normal_edge = e;
354 : : }
355 : : }
356 : :
357 : 75425551 : if (normal_edge_count == 1)
358 : 37298242 : add_control_edge (normal_edge);
359 : : }
360 : : }
361 : :
362 : :
363 : : /* Initialize local data structures and work lists. */
364 : :
365 : : static void
366 : 7895394 : ssa_prop_init (void)
367 : : {
368 : 7895394 : edge e;
369 : 7895394 : edge_iterator ei;
370 : 7895394 : basic_block bb;
371 : :
372 : : /* Worklists of SSA edges. */
373 : 7895394 : ssa_edge_worklist = BITMAP_ALLOC (NULL);
374 : 7895394 : bitmap_tree_view (ssa_edge_worklist);
375 : :
376 : : /* Worklist of basic-blocks. */
377 : 7895394 : bb_to_cfg_order = XNEWVEC (int, last_basic_block_for_fn (cfun) + 1);
378 : 7895394 : cfg_order_to_bb = XNEWVEC (int, n_basic_blocks_for_fn (cfun));
379 : 7895394 : int n = pre_and_rev_post_order_compute_fn (cfun, NULL,
380 : : cfg_order_to_bb, false);
381 : 83780417 : for (int i = 0; i < n; ++i)
382 : 75885023 : bb_to_cfg_order[cfg_order_to_bb[i]] = i;
383 : 7895394 : cfg_blocks = BITMAP_ALLOC (NULL);
384 : :
385 : : /* Initially assume that every edge in the CFG is not executable.
386 : : (including the edges coming out of the entry block). Mark blocks
387 : : as not visited, blocks not yet visited will have all their statements
388 : : simulated once an incoming edge gets executable. */
389 : 7895394 : set_gimple_stmt_max_uid (cfun, 0);
390 : 83780417 : for (int i = 0; i < n; ++i)
391 : : {
392 : 75885023 : gimple_stmt_iterator si;
393 : 75885023 : bb = BASIC_BLOCK_FOR_FN (cfun, cfg_order_to_bb[i]);
394 : :
395 : 107750154 : for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
396 : : {
397 : 31865131 : gimple *stmt = gsi_stmt (si);
398 : 31865131 : gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
399 : : }
400 : :
401 : 721242676 : for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
402 : : {
403 : 569472630 : gimple *stmt = gsi_stmt (si);
404 : 569472630 : gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
405 : : }
406 : :
407 : 75885023 : bb->flags &= ~BB_VISITED;
408 : 182491904 : FOR_EACH_EDGE (e, ei, bb->succs)
409 : 106606881 : e->flags &= ~EDGE_EXECUTABLE;
410 : : }
411 : 7895394 : uid_to_stmt.safe_grow (gimple_stmt_max_uid (cfun), true);
412 : 7895394 : }
413 : :
414 : :
415 : : /* Free allocated storage. */
416 : :
417 : : static void
418 : 7895394 : ssa_prop_fini (void)
419 : : {
420 : 7895394 : BITMAP_FREE (cfg_blocks);
421 : 7895394 : free (bb_to_cfg_order);
422 : 7895394 : free (cfg_order_to_bb);
423 : 7895394 : BITMAP_FREE (ssa_edge_worklist);
424 : 7895394 : uid_to_stmt.release ();
425 : 7895394 : }
426 : :
427 : :
428 : : /* Entry point to the propagation engine.
429 : :
430 : : The VISIT_STMT virtual function is called for every statement
431 : : visited and the VISIT_PHI virtual function is called for every PHI
432 : : node visited. */
433 : :
434 : : void
435 : 7895394 : ssa_propagation_engine::ssa_propagate (void)
436 : : {
437 : 7895394 : ssa_prop_init ();
438 : :
439 : 7895394 : curr_order = 0;
440 : :
441 : : /* Iterate until the worklists are empty. We iterate both blocks
442 : : and stmts in RPO order, prioritizing backedge processing.
443 : : Seed the algorithm by adding the successors of the entry block to the
444 : : edge worklist. */
445 : 7895394 : edge e;
446 : 7895394 : edge_iterator ei;
447 : 15790788 : FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR_FOR_FN (cfun)->succs)
448 : : {
449 : 7895394 : e->flags &= ~EDGE_EXECUTABLE;
450 : 7895394 : add_control_edge (e);
451 : : }
452 : 264045163 : while (1)
453 : : {
454 : 264045163 : int next_block_order = (bitmap_empty_p (cfg_blocks)
455 : 264045163 : ? -1 : bitmap_first_set_bit (cfg_blocks));
456 : 264045163 : int next_stmt_uid = (bitmap_empty_p (ssa_edge_worklist)
457 : 264045163 : ? -1 : bitmap_first_set_bit (ssa_edge_worklist));
458 : 264045163 : if (next_block_order == -1 && next_stmt_uid == -1)
459 : : break;
460 : :
461 : 256149769 : int next_stmt_bb_order = -1;
462 : 256149769 : gimple *next_stmt = NULL;
463 : 256149769 : if (next_stmt_uid != -1)
464 : : {
465 : 179345292 : next_stmt = uid_to_stmt[next_stmt_uid];
466 : 179345292 : next_stmt_bb_order = bb_to_cfg_order[gimple_bb (next_stmt)->index];
467 : : }
468 : :
469 : : /* Pull the next block to simulate off the worklist if it comes first. */
470 : 256149769 : if (next_block_order != -1
471 : 226757486 : && (next_stmt_bb_order == -1
472 : 226757486 : || next_block_order <= next_stmt_bb_order))
473 : : {
474 : 80642888 : curr_order = next_block_order;
475 : 80642888 : bitmap_clear_bit (cfg_blocks, next_block_order);
476 : 80642888 : basic_block bb
477 : 80642888 : = BASIC_BLOCK_FOR_FN (cfun, cfg_order_to_bb [next_block_order]);
478 : 80642888 : simulate_block (bb);
479 : 80642888 : }
480 : : /* Else simulate from the SSA edge worklist. */
481 : : else
482 : : {
483 : 175506881 : curr_order = next_stmt_bb_order;
484 : 175506881 : if (dump_file && (dump_flags & TDF_DETAILS))
485 : : {
486 : 0 : fprintf (dump_file, "\nSimulating statement: ");
487 : 0 : print_gimple_stmt (dump_file, next_stmt, 0, dump_flags);
488 : : }
489 : 175506881 : simulate_stmt (next_stmt);
490 : : }
491 : : }
492 : :
493 : 7895394 : ssa_prop_fini ();
494 : 7895394 : }
495 : :
496 : : /* Return true if STMT is of the form 'mem_ref = RHS', where 'mem_ref'
497 : : is a non-volatile pointer dereference, a structure reference or a
498 : : reference to a single _DECL. Ignore volatile memory references
499 : : because they are not interesting for the optimizers. */
500 : :
501 : : bool
502 : 29402831 : stmt_makes_single_store (gimple *stmt)
503 : : {
504 : 29402831 : tree lhs;
505 : :
506 : 29402831 : if (gimple_code (stmt) != GIMPLE_ASSIGN
507 : 29402831 : && gimple_code (stmt) != GIMPLE_CALL)
508 : : return false;
509 : :
510 : 29417444 : if (!gimple_vdef (stmt))
511 : : return false;
512 : :
513 : 2492568 : lhs = gimple_get_lhs (stmt);
514 : :
515 : : /* A call statement may have a null LHS. */
516 : 2492568 : if (!lhs)
517 : : return false;
518 : :
519 : 2492568 : return (!TREE_THIS_VOLATILE (lhs)
520 : 2492568 : && (DECL_P (lhs)
521 : 2477955 : || REFERENCE_CLASS_P (lhs)));
522 : : }
523 : :
524 : :
525 : : /* Propagation statistics. */
526 : : struct prop_stats_d
527 : : {
528 : : long num_const_prop;
529 : : long num_copy_prop;
530 : : long num_stmts_folded;
531 : : };
532 : :
533 : : static struct prop_stats_d prop_stats;
534 : :
535 : : // range_query default methods to drive from a value_of_expr() ranther than
536 : : // range_of_expr.
537 : :
538 : : tree
539 : 56087107 : substitute_and_fold_engine::value_on_edge (edge, tree expr)
540 : : {
541 : 56087107 : return value_of_expr (expr);
542 : : }
543 : :
544 : : tree
545 : 131566806 : substitute_and_fold_engine::value_of_stmt (gimple *stmt, tree name)
546 : : {
547 : 131566806 : if (!name)
548 : 0 : name = gimple_get_lhs (stmt);
549 : :
550 : 131566806 : gcc_checking_assert (!name || name == gimple_get_lhs (stmt));
551 : :
552 : 131566806 : if (name)
553 : 131566806 : return value_of_expr (name);
554 : : return NULL_TREE;
555 : : }
556 : :
557 : : bool
558 : 0 : substitute_and_fold_engine::range_of_expr (vrange &, tree, gimple *)
559 : : {
560 : 0 : return false;
561 : : }
562 : :
563 : : /* Replace USE references in statement STMT with the values stored in
564 : : PROP_VALUE. Return true if at least one reference was replaced. */
565 : :
566 : : bool
567 : 792618497 : substitute_and_fold_engine::replace_uses_in (gimple *stmt)
568 : : {
569 : 792618497 : bool replaced = false;
570 : 792618497 : use_operand_p use;
571 : 792618497 : ssa_op_iter iter;
572 : :
573 : 1166158530 : FOR_EACH_SSA_USE_OPERAND (use, stmt, iter, SSA_OP_USE)
574 : : {
575 : 373540033 : tree tuse = USE_FROM_PTR (use);
576 : 373540033 : tree val = value_of_expr (tuse, stmt);
577 : :
578 : 373540033 : if (val == tuse || val == NULL_TREE)
579 : 359823524 : continue;
580 : :
581 : 13716509 : if (!may_propagate_copy (tuse, val))
582 : 475 : continue;
583 : :
584 : 13716034 : if (TREE_CODE (val) != SSA_NAME)
585 : 5227107 : prop_stats.num_const_prop++;
586 : : else
587 : 8488927 : prop_stats.num_copy_prop++;
588 : :
589 : 13716034 : propagate_value (use, val);
590 : :
591 : 13716034 : replaced = true;
592 : : }
593 : :
594 : 792618497 : return replaced;
595 : : }
596 : :
597 : :
598 : : /* Replace propagated values into all the arguments for PHI using the
599 : : values from PROP_VALUE. */
600 : :
601 : : bool
602 : 23955326 : substitute_and_fold_engine::replace_phi_args_in (gphi *phi)
603 : : {
604 : 23955326 : size_t i;
605 : 23955326 : bool replaced = false;
606 : :
607 : 78715229 : for (i = 0; i < gimple_phi_num_args (phi); i++)
608 : : {
609 : 54759903 : tree arg = gimple_phi_arg_def (phi, i);
610 : :
611 : 54759903 : if (TREE_CODE (arg) == SSA_NAME)
612 : : {
613 : 38802786 : edge e = gimple_phi_arg_edge (phi, i);
614 : 38802786 : tree val = value_on_edge (e, arg);
615 : :
616 : 38802786 : if (val && val != arg && may_propagate_copy (arg, val))
617 : : {
618 : 1179820 : if (TREE_CODE (val) != SSA_NAME)
619 : 31834 : prop_stats.num_const_prop++;
620 : : else
621 : 1147986 : prop_stats.num_copy_prop++;
622 : :
623 : 1179820 : propagate_value (PHI_ARG_DEF_PTR (phi, i), val);
624 : 1179820 : replaced = true;
625 : :
626 : : /* If we propagated a copy and this argument flows
627 : : through an abnormal edge, update the replacement
628 : : accordingly. */
629 : 1179820 : if (TREE_CODE (val) == SSA_NAME
630 : 1147986 : && e->flags & EDGE_ABNORMAL
631 : 1179820 : && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val))
632 : : {
633 : : /* This can only occur for virtual operands, since
634 : : for the real ones SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val))
635 : : would prevent replacement. */
636 : 0 : gcc_checking_assert (virtual_operand_p (val));
637 : 0 : SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val) = 1;
638 : : }
639 : : }
640 : : }
641 : : }
642 : :
643 : 23955326 : if (dump_file && (dump_flags & TDF_DETAILS))
644 : : {
645 : 146 : if (!replaced)
646 : 146 : fprintf (dump_file, "No folding possible\n");
647 : : else
648 : : {
649 : 0 : fprintf (dump_file, "Folded into: ");
650 : 0 : print_gimple_stmt (dump_file, phi, 0, TDF_SLIM);
651 : 0 : fprintf (dump_file, "\n");
652 : : }
653 : : }
654 : :
655 : 23955326 : return replaced;
656 : : }
657 : :
658 : :
659 : : class substitute_and_fold_dom_walker : public dom_walker
660 : : {
661 : : public:
662 : 12167734 : substitute_and_fold_dom_walker (cdi_direction direction,
663 : : class substitute_and_fold_engine *engine)
664 : 12167734 : : dom_walker (direction),
665 : 12167734 : something_changed (false),
666 : 12167734 : substitute_and_fold_engine (engine)
667 : : {
668 : 12167734 : dceworklist = BITMAP_ALLOC (NULL);
669 : 12167734 : stmts_to_fixup.create (0);
670 : 12167734 : need_eh_cleanup = BITMAP_ALLOC (NULL);
671 : 12167734 : need_ab_cleanup = BITMAP_ALLOC (NULL);
672 : 12167734 : }
673 : 12167734 : ~substitute_and_fold_dom_walker ()
674 : 12167734 : {
675 : 12167734 : BITMAP_FREE (dceworklist);
676 : 12167734 : stmts_to_fixup.release ();
677 : 12167734 : BITMAP_FREE (need_eh_cleanup);
678 : 12167734 : BITMAP_FREE (need_ab_cleanup);
679 : 12167734 : }
680 : :
681 : : edge before_dom_children (basic_block) final override;
682 : 121335207 : void after_dom_children (basic_block bb) final override
683 : : {
684 : 121335207 : substitute_and_fold_engine->post_fold_bb (bb);
685 : 121335207 : }
686 : :
687 : : bool something_changed;
688 : : bitmap dceworklist;
689 : : vec<gimple *> stmts_to_fixup;
690 : : bitmap need_eh_cleanup;
691 : : bitmap need_ab_cleanup;
692 : :
693 : : class substitute_and_fold_engine *substitute_and_fold_engine;
694 : :
695 : : private:
696 : : void foreach_new_stmt_in_bb (gimple_stmt_iterator old_gsi,
697 : : gimple_stmt_iterator new_gsi);
698 : : };
699 : :
700 : : /* Call post_new_stmt for each new statement that has been added
701 : : to the current BB. OLD_GSI is the statement iterator before the BB
702 : : changes ocurred. NEW_GSI is the iterator which may contain new
703 : : statements. */
704 : :
705 : : void
706 : 14583998 : substitute_and_fold_dom_walker::foreach_new_stmt_in_bb
707 : : (gimple_stmt_iterator old_gsi,
708 : : gimple_stmt_iterator new_gsi)
709 : : {
710 : 14583998 : basic_block bb = gsi_bb (new_gsi);
711 : 14583998 : if (gsi_end_p (old_gsi))
712 : 3208314 : old_gsi = gsi_start_bb (bb);
713 : : else
714 : 12979841 : gsi_next (&old_gsi);
715 : 14645986 : while (gsi_stmt (old_gsi) != gsi_stmt (new_gsi))
716 : : {
717 : 61988 : gimple *stmt = gsi_stmt (old_gsi);
718 : 61988 : substitute_and_fold_engine->post_new_stmt (stmt);
719 : 61988 : gsi_next (&old_gsi);
720 : : }
721 : 14583998 : }
722 : :
723 : : bool
724 : 121335207 : substitute_and_fold_engine::propagate_into_phi_args (basic_block bb)
725 : : {
726 : 121335207 : edge e;
727 : 121335207 : edge_iterator ei;
728 : 121335207 : bool propagated = false;
729 : :
730 : : /* Visit BB successor PHI nodes and replace PHI args. */
731 : 286564885 : FOR_EACH_EDGE (e, ei, bb->succs)
732 : : {
733 : 165229678 : for (gphi_iterator gpi = gsi_start_phis (e->dest);
734 : 275617011 : !gsi_end_p (gpi); gsi_next (&gpi))
735 : : {
736 : 110387333 : gphi *phi = gpi.phi ();
737 : 110387333 : use_operand_p use_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, e);
738 : 110387333 : tree arg = USE_FROM_PTR (use_p);
739 : 178351667 : if (TREE_CODE (arg) != SSA_NAME
740 : 110387333 : || virtual_operand_p (arg))
741 : 67964334 : continue;
742 : 42422999 : tree val = value_on_edge (e, arg);
743 : 42422999 : if (val
744 : 3141559 : && is_gimple_min_invariant (val)
745 : 44364343 : && may_propagate_copy (arg, val))
746 : : {
747 : 1939499 : propagate_value (use_p, val);
748 : 1939499 : propagated = true;
749 : : }
750 : : }
751 : : }
752 : 121335207 : return propagated;
753 : : }
754 : :
755 : : edge
756 : 121335207 : substitute_and_fold_dom_walker::before_dom_children (basic_block bb)
757 : : {
758 : 121335207 : substitute_and_fold_engine->pre_fold_bb (bb);
759 : :
760 : : /* Propagate known values into PHI nodes. */
761 : 121335207 : for (gphi_iterator i = gsi_start_phis (bb);
762 : 168635601 : !gsi_end_p (i);
763 : 47300394 : gsi_next (&i))
764 : : {
765 : 47300394 : gphi *phi = i.phi ();
766 : 47300394 : tree res = gimple_phi_result (phi);
767 : 94600788 : if (virtual_operand_p (res))
768 : 21091917 : continue;
769 : 26208477 : if (dump_file && (dump_flags & TDF_DETAILS))
770 : : {
771 : 154 : fprintf (dump_file, "Folding PHI node: ");
772 : 154 : print_gimple_stmt (dump_file, phi, 0, TDF_SLIM);
773 : : }
774 : 26208477 : if (res && TREE_CODE (res) == SSA_NAME)
775 : : {
776 : 26208477 : tree sprime = substitute_and_fold_engine->value_of_expr (res, phi);
777 : 28461628 : if (sprime
778 : 26208477 : && sprime != res
779 : 26208477 : && may_propagate_copy (res, sprime))
780 : : {
781 : 2253151 : if (dump_file && (dump_flags & TDF_DETAILS))
782 : : {
783 : 8 : fprintf (dump_file, "Queued PHI for removal. Folds to: ");
784 : 8 : print_generic_expr (dump_file, sprime);
785 : 8 : fprintf (dump_file, "\n");
786 : : }
787 : 2253151 : bitmap_set_bit (dceworklist, SSA_NAME_VERSION (res));
788 : : /* As this now constitutes a copy duplicate points-to
789 : : and range info appropriately. */
790 : 2253151 : if (TREE_CODE (sprime) == SSA_NAME)
791 : 1391317 : maybe_duplicate_ssa_info_at_copy (res, sprime);
792 : 2253151 : continue;
793 : : }
794 : : }
795 : 23955326 : something_changed |= substitute_and_fold_engine->replace_phi_args_in (phi);
796 : : }
797 : :
798 : : /* Propagate known values into stmts. In some case it exposes
799 : : more trivially deletable stmts to walk backward. */
800 : 242670414 : for (gimple_stmt_iterator i = gsi_start_bb (bb);
801 : 928698709 : !gsi_end_p (i);
802 : 807363502 : gsi_next (&i))
803 : : {
804 : 807363502 : bool did_replace;
805 : 807363502 : gimple *stmt = gsi_stmt (i);
806 : :
807 : 807363502 : substitute_and_fold_engine->pre_fold_stmt (stmt);
808 : :
809 : 807363502 : if (dump_file && (dump_flags & TDF_DETAILS))
810 : : {
811 : 1767 : fprintf (dump_file, "Folding statement: ");
812 : 1767 : print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
813 : : }
814 : :
815 : : /* No point propagating into a stmt we have a value for we
816 : : can propagate into all uses. Mark it for removal instead. */
817 : 807363502 : tree lhs = gimple_get_lhs (stmt);
818 : 807363502 : if (lhs && TREE_CODE (lhs) == SSA_NAME)
819 : : {
820 : 179162484 : tree sprime = substitute_and_fold_engine->value_of_stmt (stmt, lhs);
821 : 193907489 : if (sprime
822 : 179162484 : && sprime != lhs
823 : 14763825 : && may_propagate_copy (lhs, sprime)
824 : 14762475 : && !stmt_could_throw_p (cfun, stmt)
825 : 193911562 : && !gimple_has_side_effects (stmt))
826 : : {
827 : 14745005 : if (dump_file && (dump_flags & TDF_DETAILS))
828 : : {
829 : 56 : fprintf (dump_file, "Queued stmt for removal. Folds to: ");
830 : 56 : print_generic_expr (dump_file, sprime);
831 : 56 : fprintf (dump_file, "\n");
832 : : }
833 : 14745005 : bitmap_set_bit (dceworklist, SSA_NAME_VERSION (lhs));
834 : : /* As this now constitutes a copy duplicate points-to
835 : : and range info appropriately. */
836 : 14745005 : if (TREE_CODE (sprime) == SSA_NAME)
837 : 8803477 : maybe_duplicate_ssa_info_at_copy (lhs, sprime);
838 : 14745005 : continue;
839 : : }
840 : : }
841 : :
842 : : /* Replace the statement with its folded version and mark it
843 : : folded. */
844 : 792618497 : did_replace = false;
845 : 792618497 : gimple *old_stmt = stmt;
846 : 792618497 : bool was_noreturn = false;
847 : 792618497 : bool can_make_abnormal_goto = false;
848 : 792618497 : if (is_gimple_call (stmt))
849 : : {
850 : 52841228 : was_noreturn = gimple_call_noreturn_p (stmt);
851 : 52841228 : can_make_abnormal_goto = stmt_can_make_abnormal_goto (stmt);
852 : : }
853 : :
854 : : /* Replace real uses in the statement. */
855 : 792618497 : did_replace |= substitute_and_fold_engine->replace_uses_in (stmt);
856 : :
857 : 792618497 : gimple_stmt_iterator prev_gsi = i;
858 : 792618497 : gsi_prev (&prev_gsi);
859 : :
860 : : /* If we made a replacement, fold the statement. */
861 : 792618497 : if (did_replace)
862 : : {
863 : 12898030 : fold_stmt (&i, follow_single_use_edges);
864 : 12898030 : stmt = gsi_stmt (i);
865 : 12898030 : gimple_set_modified (stmt, true);
866 : : }
867 : : /* Also fold if we want to fold all statements. */
868 : 779720467 : else if (substitute_and_fold_engine->fold_all_stmts
869 : 779720467 : && fold_stmt (&i, follow_single_use_edges))
870 : : {
871 : 0 : did_replace = true;
872 : 0 : stmt = gsi_stmt (i);
873 : 0 : gimple_set_modified (stmt, true);
874 : : }
875 : :
876 : : /* Some statements may be simplified using propagator
877 : : specific information. Do this before propagating
878 : : into the stmt to not disturb pass specific information. */
879 : 792618497 : update_stmt_if_modified (stmt);
880 : 792618497 : if (substitute_and_fold_engine->fold_stmt (&i))
881 : : {
882 : 2046608 : did_replace = true;
883 : 2046608 : prop_stats.num_stmts_folded++;
884 : 2046608 : stmt = gsi_stmt (i);
885 : 2046608 : gimple_set_modified (stmt, true);
886 : : }
887 : :
888 : : /* If this is a control statement the propagator left edges
889 : : unexecuted on force the condition in a way consistent with
890 : : that. See PR66945 for cases where the propagator can end
891 : : up with a different idea of a taken edge than folding
892 : : (once undefined behavior is involved). */
893 : 792618497 : if (gimple_code (stmt) == GIMPLE_COND)
894 : : {
895 : 42432691 : if ((EDGE_SUCC (bb, 0)->flags & EDGE_EXECUTABLE)
896 : 42432691 : ^ (EDGE_SUCC (bb, 1)->flags & EDGE_EXECUTABLE))
897 : : {
898 : 402417 : if (((EDGE_SUCC (bb, 0)->flags & EDGE_TRUE_VALUE) != 0)
899 : 402417 : == ((EDGE_SUCC (bb, 0)->flags & EDGE_EXECUTABLE) != 0))
900 : 95905 : gimple_cond_make_true (as_a <gcond *> (stmt));
901 : : else
902 : 306512 : gimple_cond_make_false (as_a <gcond *> (stmt));
903 : 402417 : gimple_set_modified (stmt, true);
904 : 402417 : did_replace = true;
905 : : }
906 : : }
907 : :
908 : : /* Now cleanup. */
909 : 792618497 : if (did_replace)
910 : : {
911 : 14583998 : foreach_new_stmt_in_bb (prev_gsi, i);
912 : :
913 : : /* If we cleaned up EH information from the statement,
914 : : remove EH edges. */
915 : 14583998 : if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
916 : 155838 : bitmap_set_bit (need_eh_cleanup, bb->index);
917 : :
918 : : /* If we turned a call with possible abnormal control transfer
919 : : into one that doesn't, remove abnormal edges. */
920 : 14583998 : if (can_make_abnormal_goto
921 : 14583998 : && !stmt_can_make_abnormal_goto (stmt))
922 : 3 : bitmap_set_bit (need_ab_cleanup, bb->index);
923 : :
924 : : /* If we turned a not noreturn call into a noreturn one
925 : : schedule it for fixup. */
926 : 14583998 : if (!was_noreturn
927 : 14454761 : && is_gimple_call (stmt)
928 : 15991996 : && gimple_call_noreturn_p (stmt))
929 : 70 : stmts_to_fixup.safe_push (stmt);
930 : :
931 : 14583998 : if (gimple_assign_single_p (stmt))
932 : : {
933 : 3461432 : tree rhs = gimple_assign_rhs1 (stmt);
934 : :
935 : 3461432 : if (TREE_CODE (rhs) == ADDR_EXPR)
936 : 392756 : recompute_tree_invariant_for_addr_expr (rhs);
937 : : }
938 : :
939 : : /* Determine what needs to be done to update the SSA form. */
940 : 14583998 : update_stmt_if_modified (stmt);
941 : 14583998 : if (!is_gimple_debug (stmt))
942 : 10788278 : something_changed = true;
943 : : }
944 : :
945 : 792618497 : if (dump_file && (dump_flags & TDF_DETAILS))
946 : : {
947 : 1711 : if (did_replace)
948 : : {
949 : 145 : fprintf (dump_file, "Folded into: ");
950 : 145 : print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
951 : 145 : fprintf (dump_file, "\n");
952 : : }
953 : : else
954 : 1566 : fprintf (dump_file, "Not folded\n");
955 : : }
956 : : }
957 : :
958 : 121335207 : something_changed |= substitute_and_fold_engine->propagate_into_phi_args (bb);
959 : :
960 : 121335207 : return NULL;
961 : : }
962 : :
963 : :
964 : :
965 : : /* Perform final substitution and folding of propagated values.
966 : : Process the whole function if BLOCK is null, otherwise only
967 : : process the blocks that BLOCK dominates. In the latter case,
968 : : it is the caller's responsibility to ensure that dominator
969 : : information is available and up-to-date.
970 : :
971 : : PROP_VALUE[I] contains the single value that should be substituted
972 : : at every use of SSA name N_I. If PROP_VALUE is NULL, no values are
973 : : substituted.
974 : :
975 : : If FOLD_FN is non-NULL the function will be invoked on all statements
976 : : before propagating values for pass specific simplification.
977 : :
978 : : DO_DCE is true if trivially dead stmts can be removed.
979 : :
980 : : If DO_DCE is true, the statements within a BB are walked from
981 : : last to first element. Otherwise we scan from first to last element.
982 : :
983 : : Return TRUE when something changed. */
984 : :
985 : : bool
986 : 12167734 : substitute_and_fold_engine::substitute_and_fold (basic_block block)
987 : : {
988 : 12167734 : if (dump_file && (dump_flags & TDF_DETAILS))
989 : 157 : fprintf (dump_file, "\nSubstituting values and folding statements\n\n");
990 : :
991 : 12167734 : memset (&prop_stats, 0, sizeof (prop_stats));
992 : :
993 : : /* Don't call calculate_dominance_info when iterating over a subgraph.
994 : : Callers that are using the interface this way are likely to want to
995 : : iterate over several disjoint subgraphs, and it would be expensive
996 : : in enable-checking builds to revalidate the whole dominance tree
997 : : each time. */
998 : 12167734 : if (block)
999 : 1181 : gcc_assert (dom_info_state (CDI_DOMINATORS));
1000 : : else
1001 : 12166553 : calculate_dominance_info (CDI_DOMINATORS);
1002 : 12167734 : substitute_and_fold_dom_walker walker (CDI_DOMINATORS, this);
1003 : 12167734 : walker.walk (block ? block : ENTRY_BLOCK_PTR_FOR_FN (cfun));
1004 : :
1005 : 12167734 : simple_dce_from_worklist (walker.dceworklist, walker.need_eh_cleanup);
1006 : 12167734 : if (!bitmap_empty_p (walker.need_eh_cleanup))
1007 : 36768 : gimple_purge_all_dead_eh_edges (walker.need_eh_cleanup);
1008 : 12167734 : if (!bitmap_empty_p (walker.need_ab_cleanup))
1009 : 3 : gimple_purge_all_dead_abnormal_call_edges (walker.need_ab_cleanup);
1010 : :
1011 : : /* Fixup stmts that became noreturn calls. This may require splitting
1012 : : blocks and thus isn't possible during the dominator walk. Do this
1013 : : in reverse order so we don't inadvertedly remove a stmt we want to
1014 : : fixup by visiting a dominating now noreturn call first. */
1015 : 12167804 : while (!walker.stmts_to_fixup.is_empty ())
1016 : : {
1017 : 70 : gimple *stmt = walker.stmts_to_fixup.pop ();
1018 : 76 : if (!gimple_bb (stmt))
1019 : 6 : continue;
1020 : 64 : if (dump_file && dump_flags & TDF_DETAILS)
1021 : : {
1022 : 0 : fprintf (dump_file, "Fixing up noreturn call ");
1023 : 0 : print_gimple_stmt (dump_file, stmt, 0);
1024 : 0 : fprintf (dump_file, "\n");
1025 : : }
1026 : 64 : fixup_noreturn_call (stmt);
1027 : : }
1028 : :
1029 : 12167734 : statistics_counter_event (cfun, "Constants propagated",
1030 : 12167734 : prop_stats.num_const_prop);
1031 : 12167734 : statistics_counter_event (cfun, "Copies propagated",
1032 : 12167734 : prop_stats.num_copy_prop);
1033 : 12167734 : statistics_counter_event (cfun, "Statements folded",
1034 : 12167734 : prop_stats.num_stmts_folded);
1035 : :
1036 : 12167734 : return walker.something_changed;
1037 : 12167734 : }
1038 : :
1039 : :
1040 : : /* Return true if we may propagate ORIG into DEST, false otherwise.
1041 : : If DEST_NOT_ABNORMAL_PHI_EDGE_P is true then assume the propagation does
1042 : : not happen into a PHI argument which flows in from an abnormal edge
1043 : : which relaxes some constraints. */
1044 : :
1045 : : bool
1046 : 151258499 : may_propagate_copy (tree dest, tree orig, bool dest_not_abnormal_phi_edge_p)
1047 : : {
1048 : 151258499 : tree type_d = TREE_TYPE (dest);
1049 : 151258499 : tree type_o = TREE_TYPE (orig);
1050 : :
1051 : : /* If ORIG is a default definition which flows in from an abnormal edge
1052 : : then the copy can be propagated. It is important that we do so to avoid
1053 : : uninitialized copies. */
1054 : 151258499 : if (TREE_CODE (orig) == SSA_NAME
1055 : 105127436 : && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig)
1056 : 26606 : && SSA_NAME_IS_DEFAULT_DEF (orig)
1057 : 151261669 : && (SSA_NAME_VAR (orig) == NULL_TREE
1058 : 3170 : || VAR_P (SSA_NAME_VAR (orig))))
1059 : : ;
1060 : : /* Otherwise if ORIG just flows in from an abnormal edge then the copy cannot
1061 : : be propagated. */
1062 : 151255726 : else if (TREE_CODE (orig) == SSA_NAME
1063 : 151255726 : && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig))
1064 : : return false;
1065 : : /* Similarly if DEST flows in from an abnormal edge then the copy cannot be
1066 : : propagated. If we know we do not propagate into such a PHI argument this
1067 : : does not apply. */
1068 : 151231893 : else if (!dest_not_abnormal_phi_edge_p
1069 : 79119190 : && TREE_CODE (dest) == SSA_NAME
1070 : 230351083 : && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (dest))
1071 : : return false;
1072 : :
1073 : : /* Do not copy between types for which we *do* need a conversion. */
1074 : 151219884 : if (!useless_type_conversion_p (type_d, type_o))
1075 : : return false;
1076 : :
1077 : : /* Generally propagating virtual operands is not ok as that may
1078 : : create overlapping life-ranges. */
1079 : 151203519 : if (TREE_CODE (dest) == SSA_NAME && virtual_operand_p (dest))
1080 : : return false;
1081 : :
1082 : : /* Keep lhs of [[gnu::musttail]] calls as is, those need to be still
1083 : : tail callable. */
1084 : 150714488 : if (TREE_CODE (dest) == SSA_NAME
1085 : 150556636 : && is_gimple_call (SSA_NAME_DEF_STMT (dest))
1086 : 152009166 : && gimple_call_must_tail_p (as_a <gcall *> (SSA_NAME_DEF_STMT (dest))))
1087 : : return false;
1088 : :
1089 : : /* Anything else is OK. */
1090 : : return true;
1091 : : }
1092 : :
1093 : : /* Like may_propagate_copy, but use as the destination expression
1094 : : the principal expression (typically, the RHS) contained in
1095 : : statement DEST. This is more efficient when working with the
1096 : : gimple tuples representation. */
1097 : :
1098 : : bool
1099 : 351740 : may_propagate_copy_into_stmt (gimple *dest, tree orig)
1100 : : {
1101 : 351740 : tree type_d;
1102 : 351740 : tree type_o;
1103 : :
1104 : : /* If the statement is a switch or a single-rhs assignment,
1105 : : then the expression to be replaced by the propagation may
1106 : : be an SSA_NAME. Fortunately, there is an explicit tree
1107 : : for the expression, so we delegate to may_propagate_copy. */
1108 : :
1109 : 351740 : if (gimple_assign_single_p (dest))
1110 : 172795 : return may_propagate_copy (gimple_assign_rhs1 (dest), orig, true);
1111 : 178945 : else if (gswitch *dest_swtch = dyn_cast <gswitch *> (dest))
1112 : 0 : return may_propagate_copy (gimple_switch_index (dest_swtch), orig, true);
1113 : :
1114 : : /* In other cases, the expression is not materialized, so there
1115 : : is no destination to pass to may_propagate_copy. On the other
1116 : : hand, the expression cannot be an SSA_NAME, so the analysis
1117 : : is much simpler. */
1118 : :
1119 : 178945 : if (TREE_CODE (orig) == SSA_NAME
1120 : 178945 : && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig))
1121 : : return false;
1122 : :
1123 : 178945 : if (is_gimple_assign (dest))
1124 : 145360 : type_d = TREE_TYPE (gimple_assign_lhs (dest));
1125 : 33585 : else if (gimple_code (dest) == GIMPLE_COND)
1126 : 28935 : type_d = boolean_type_node;
1127 : 4650 : else if (is_gimple_call (dest)
1128 : 4650 : && gimple_call_lhs (dest) != NULL_TREE)
1129 : 4650 : type_d = TREE_TYPE (gimple_call_lhs (dest));
1130 : : else
1131 : 0 : gcc_unreachable ();
1132 : :
1133 : 178945 : type_o = TREE_TYPE (orig);
1134 : :
1135 : 178945 : if (!useless_type_conversion_p (type_d, type_o))
1136 : : return false;
1137 : :
1138 : : return true;
1139 : : }
1140 : :
1141 : : /* Replace *OP_P with value VAL (assumed to be a constant or another SSA_NAME).
1142 : :
1143 : : Use this version when not const/copy propagating values. For example,
1144 : : PRE uses this version when building expressions as they would appear
1145 : : in specific blocks taking into account actions of PHI nodes.
1146 : :
1147 : : The statement in which an expression has been replaced should be
1148 : : folded using fold_stmt_inplace. */
1149 : :
1150 : : void
1151 : 54714532 : replace_exp (use_operand_p op_p, tree val)
1152 : : {
1153 : 54714532 : if (TREE_CODE (val) == SSA_NAME || CONSTANT_CLASS_P (val))
1154 : 50885675 : SET_USE (op_p, val);
1155 : : else
1156 : 3828857 : SET_USE (op_p, unshare_expr (val));
1157 : 54714532 : }
1158 : :
1159 : :
1160 : : /* Propagate the value VAL (assumed to be a constant or another SSA_NAME)
1161 : : into the operand pointed to by OP_P.
1162 : :
1163 : : Use this version for const/copy propagation as it will perform additional
1164 : : checks to ensure validity of the const/copy propagation. */
1165 : :
1166 : : void
1167 : 47802531 : propagate_value (use_operand_p op_p, tree val)
1168 : : {
1169 : 47802531 : if (flag_checking)
1170 : : {
1171 : 47802048 : bool ab = (is_a <gphi *> (USE_STMT (op_p))
1172 : 64263500 : && (gimple_phi_arg_edge (as_a <gphi *> (USE_STMT (op_p)),
1173 : 16461452 : PHI_ARG_INDEX_FROM_USE (op_p))
1174 : 16461452 : ->flags & EDGE_ABNORMAL));
1175 : 47802048 : gcc_assert (may_propagate_copy (USE_FROM_PTR (op_p), val, !ab));
1176 : : }
1177 : 47802531 : replace_exp (op_p, val);
1178 : 47802531 : }
1179 : :
1180 : :
1181 : : /* Propagate the value VAL (assumed to be a constant or another SSA_NAME)
1182 : : into the tree pointed to by OP_P.
1183 : :
1184 : : Use this version for const/copy propagation when SSA operands are not
1185 : : available. It will perform the additional checks to ensure validity of
1186 : : the const/copy propagation, but will not update any operand information.
1187 : : Be sure to mark the stmt as modified. */
1188 : :
1189 : : void
1190 : 372571 : propagate_tree_value (tree *op_p, tree val)
1191 : : {
1192 : 372571 : if (TREE_CODE (val) == SSA_NAME)
1193 : 336798 : *op_p = val;
1194 : : else
1195 : 35773 : *op_p = unshare_expr (val);
1196 : 372571 : }
1197 : :
1198 : :
1199 : : /* Like propagate_tree_value, but use as the operand to replace
1200 : : the principal expression (typically, the RHS) contained in the
1201 : : statement referenced by iterator GSI. Note that it is not
1202 : : always possible to update the statement in-place, so a new
1203 : : statement may be created to replace the original. */
1204 : :
1205 : : void
1206 : 372571 : propagate_tree_value_into_stmt (gimple_stmt_iterator *gsi, tree val)
1207 : : {
1208 : 372571 : gimple *stmt = gsi_stmt (*gsi);
1209 : :
1210 : 372571 : if (is_gimple_assign (stmt))
1211 : : {
1212 : 336573 : tree expr = NULL_TREE;
1213 : 336573 : if (gimple_assign_single_p (stmt))
1214 : 186721 : expr = gimple_assign_rhs1 (stmt);
1215 : 336573 : propagate_tree_value (&expr, val);
1216 : 336573 : gimple_assign_set_rhs_from_tree (gsi, expr);
1217 : : }
1218 : 35998 : else if (gcond *cond_stmt = dyn_cast <gcond *> (stmt))
1219 : : {
1220 : 31131 : tree lhs = NULL_TREE;
1221 : 31131 : tree rhs = build_zero_cst (TREE_TYPE (val));
1222 : 31131 : propagate_tree_value (&lhs, val);
1223 : 31131 : gimple_cond_set_code (cond_stmt, NE_EXPR);
1224 : 31131 : gimple_cond_set_lhs (cond_stmt, lhs);
1225 : 31131 : gimple_cond_set_rhs (cond_stmt, rhs);
1226 : : }
1227 : 4867 : else if (is_gimple_call (stmt)
1228 : 4867 : && gimple_call_lhs (stmt) != NULL_TREE)
1229 : : {
1230 : 4867 : tree expr = NULL_TREE;
1231 : 4867 : propagate_tree_value (&expr, val);
1232 : 4867 : replace_call_with_value (gsi, expr);
1233 : : }
1234 : 0 : else if (gswitch *swtch_stmt = dyn_cast <gswitch *> (stmt))
1235 : 0 : propagate_tree_value (gimple_switch_index_ptr (swtch_stmt), val);
1236 : : else
1237 : 0 : gcc_unreachable ();
1238 : 372571 : }
1239 : :
1240 : : /* Check exits of each loop in FUN, walk over loop closed PHIs in
1241 : : each exit basic block and propagate degenerate PHIs. */
1242 : :
1243 : : unsigned
1244 : 240769 : clean_up_loop_closed_phi (function *fun)
1245 : : {
1246 : 240769 : gphi *phi;
1247 : 240769 : tree rhs;
1248 : 240769 : tree lhs;
1249 : 240769 : gphi_iterator gsi;
1250 : :
1251 : : /* Avoid possibly quadratic work when scanning for loop exits across
1252 : : all loops of a nest. */
1253 : 240769 : if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS))
1254 : : return 0;
1255 : :
1256 : : /* replace_uses_by might purge dead EH edges and we want it to also
1257 : : remove dominated blocks. */
1258 : 240769 : calculate_dominance_info (CDI_DOMINATORS);
1259 : :
1260 : : /* Walk over loop in function. */
1261 : 1358625 : for (auto loop : loops_list (fun, 0))
1262 : : {
1263 : : /* Check each exit edege of loop. */
1264 : 636318 : auto_vec<edge> exits = get_loop_exit_edges (loop);
1265 : 3121291 : for (edge e : exits)
1266 : 2226425 : if (single_pred_p (e->dest))
1267 : : /* Walk over loop-closed PHIs. */
1268 : 2169931 : for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi);)
1269 : : {
1270 : 1168339 : phi = gsi.phi ();
1271 : 1168339 : rhs = gimple_phi_arg_def (phi, 0);
1272 : 1168339 : lhs = gimple_phi_result (phi);
1273 : :
1274 : 2336249 : if (virtual_operand_p (rhs))
1275 : : {
1276 : 604128 : imm_use_iterator iter;
1277 : 604128 : use_operand_p use_p;
1278 : 604128 : gimple *stmt;
1279 : :
1280 : 1418891 : FOR_EACH_IMM_USE_STMT (stmt, iter, lhs)
1281 : 2457607 : FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
1282 : 1425550 : SET_USE (use_p, rhs);
1283 : :
1284 : 604128 : if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
1285 : 48 : SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs) = 1;
1286 : 604128 : remove_phi_node (&gsi, true);
1287 : : }
1288 : 564211 : else if (may_propagate_copy (lhs, rhs))
1289 : : {
1290 : : /* Dump details. */
1291 : 564175 : if (dump_file && (dump_flags & TDF_DETAILS))
1292 : : {
1293 : 3 : fprintf (dump_file, " Replacing '");
1294 : 3 : print_generic_expr (dump_file, lhs, dump_flags);
1295 : 3 : fprintf (dump_file, "' with '");
1296 : 3 : print_generic_expr (dump_file, rhs, dump_flags);
1297 : 3 : fprintf (dump_file, "'\n");
1298 : : }
1299 : :
1300 : 564175 : replace_uses_by (lhs, rhs);
1301 : 564175 : remove_phi_node (&gsi, true);
1302 : : }
1303 : : else
1304 : 36 : gsi_next (&gsi);
1305 : : }
1306 : 636318 : }
1307 : :
1308 : 240769 : return 0;
1309 : : }
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