1/* Optimization of PHI nodes by converting them into straightline code.
2 Copyright (C) 2004-2017 Free Software Foundation, Inc.
3
4This file is part of GCC.
5
6GCC is free software; you can redistribute it and/or modify it
7under the terms of the GNU General Public License as published by the
8Free Software Foundation; either version 3, or (at your option) any
9later version.
10
11GCC is distributed in the hope that it will be useful, but WITHOUT
12ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14for more details.
15
16You should have received a copy of the GNU General Public License
17along with GCC; see the file COPYING3. If not see
18<http://www.gnu.org/licenses/>. */
19
20#include "config.h"
21#include "system.h"
22#include "coretypes.h"
23#include "backend.h"
24#include "insn-codes.h"
25#include "rtl.h"
26#include "tree.h"
27#include "gimple.h"
28#include "cfghooks.h"
29#include "tree-pass.h"
30#include "ssa.h"
31#include "optabs-tree.h"
32#include "insn-config.h"
33#include "gimple-pretty-print.h"
34#include "fold-const.h"
35#include "stor-layout.h"
36#include "cfganal.h"
37#include "gimplify.h"
38#include "gimple-iterator.h"
39#include "gimplify-me.h"
40#include "tree-cfg.h"
41#include "tree-dfa.h"
42#include "domwalk.h"
43#include "cfgloop.h"
44#include "tree-data-ref.h"
45#include "tree-scalar-evolution.h"
46#include "tree-inline.h"
47#include "params.h"
48
49static unsigned int tree_ssa_phiopt_worker (bool, bool);
50static bool conditional_replacement (basic_block, basic_block,
51 edge, edge, gphi *, tree, tree);
52static gphi *factor_out_conditional_conversion (edge, edge, gphi *, tree, tree,
53 gimple *);
54static int value_replacement (basic_block, basic_block,
55 edge, edge, gimple *, tree, tree);
56static bool minmax_replacement (basic_block, basic_block,
57 edge, edge, gimple *, tree, tree);
58static bool abs_replacement (basic_block, basic_block,
59 edge, edge, gimple *, tree, tree);
60static bool cond_store_replacement (basic_block, basic_block, edge, edge,
61 hash_set<tree> *);
62static bool cond_if_else_store_replacement (basic_block, basic_block, basic_block);
63static hash_set<tree> * get_non_trapping ();
64static void replace_phi_edge_with_variable (basic_block, edge, gimple *, tree);
65static void hoist_adjacent_loads (basic_block, basic_block,
66 basic_block, basic_block);
67static bool gate_hoist_loads (void);
68
69/* This pass tries to transform conditional stores into unconditional
70 ones, enabling further simplifications with the simpler then and else
71 blocks. In particular it replaces this:
72
73 bb0:
74 if (cond) goto bb2; else goto bb1;
75 bb1:
76 *p = RHS;
77 bb2:
78
79 with
80
81 bb0:
82 if (cond) goto bb1; else goto bb2;
83 bb1:
84 condtmp' = *p;
85 bb2:
86 condtmp = PHI <RHS, condtmp'>
87 *p = condtmp;
88
89 This transformation can only be done under several constraints,
90 documented below. It also replaces:
91
92 bb0:
93 if (cond) goto bb2; else goto bb1;
94 bb1:
95 *p = RHS1;
96 goto bb3;
97 bb2:
98 *p = RHS2;
99 bb3:
100
101 with
102
103 bb0:
104 if (cond) goto bb3; else goto bb1;
105 bb1:
106 bb3:
107 condtmp = PHI <RHS1, RHS2>
108 *p = condtmp; */
109
110static unsigned int
111tree_ssa_cs_elim (void)
112{
113 unsigned todo;
114 /* ??? We are not interested in loop related info, but the following
115 will create it, ICEing as we didn't init loops with pre-headers.
116 An interfacing issue of find_data_references_in_bb. */
117 loop_optimizer_init (LOOPS_NORMAL);
118 scev_initialize ();
119 todo = tree_ssa_phiopt_worker (true, false);
120 scev_finalize ();
121 loop_optimizer_finalize ();
122 return todo;
123}
124
125/* Return the singleton PHI in the SEQ of PHIs for edges E0 and E1. */
126
127static gphi *
128single_non_singleton_phi_for_edges (gimple_seq seq, edge e0, edge e1)
129{
130 gimple_stmt_iterator i;
131 gphi *phi = NULL;
132 if (gimple_seq_singleton_p (seq))
133 return as_a <gphi *> (gsi_stmt (gsi_start (seq)));
134 for (i = gsi_start (seq); !gsi_end_p (i); gsi_next (&i))
135 {
136 gphi *p = as_a <gphi *> (gsi_stmt (i));
137 /* If the PHI arguments are equal then we can skip this PHI. */
138 if (operand_equal_for_phi_arg_p (gimple_phi_arg_def (p, e0->dest_idx),
139 gimple_phi_arg_def (p, e1->dest_idx)))
140 continue;
141
142 /* If we already have a PHI that has the two edge arguments are
143 different, then return it is not a singleton for these PHIs. */
144 if (phi)
145 return NULL;
146
147 phi = p;
148 }
149 return phi;
150}
151
152/* The core routine of conditional store replacement and normal
153 phi optimizations. Both share much of the infrastructure in how
154 to match applicable basic block patterns. DO_STORE_ELIM is true
155 when we want to do conditional store replacement, false otherwise.
156 DO_HOIST_LOADS is true when we want to hoist adjacent loads out
157 of diamond control flow patterns, false otherwise. */
158static unsigned int
159tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads)
160{
161 basic_block bb;
162 basic_block *bb_order;
163 unsigned n, i;
164 bool cfgchanged = false;
165 hash_set<tree> *nontrap = 0;
166
167 if (do_store_elim)
168 /* Calculate the set of non-trapping memory accesses. */
169 nontrap = get_non_trapping ();
170
171 /* Search every basic block for COND_EXPR we may be able to optimize.
172
173 We walk the blocks in order that guarantees that a block with
174 a single predecessor is processed before the predecessor.
175 This ensures that we collapse inner ifs before visiting the
176 outer ones, and also that we do not try to visit a removed
177 block. */
178 bb_order = single_pred_before_succ_order ();
179 n = n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS;
180
181 for (i = 0; i < n; i++)
182 {
183 gimple *cond_stmt;
184 gphi *phi;
185 basic_block bb1, bb2;
186 edge e1, e2;
187 tree arg0, arg1;
188
189 bb = bb_order[i];
190
191 cond_stmt = last_stmt (bb);
192 /* Check to see if the last statement is a GIMPLE_COND. */
193 if (!cond_stmt
194 || gimple_code (cond_stmt) != GIMPLE_COND)
195 continue;
196
197 e1 = EDGE_SUCC (bb, 0);
198 bb1 = e1->dest;
199 e2 = EDGE_SUCC (bb, 1);
200 bb2 = e2->dest;
201
202 /* We cannot do the optimization on abnormal edges. */
203 if ((e1->flags & EDGE_ABNORMAL) != 0
204 || (e2->flags & EDGE_ABNORMAL) != 0)
205 continue;
206
207 /* If either bb1's succ or bb2 or bb2's succ is non NULL. */
208 if (EDGE_COUNT (bb1->succs) == 0
209 || bb2 == NULL
210 || EDGE_COUNT (bb2->succs) == 0)
211 continue;
212
213 /* Find the bb which is the fall through to the other. */
214 if (EDGE_SUCC (bb1, 0)->dest == bb2)
215 ;
216 else if (EDGE_SUCC (bb2, 0)->dest == bb1)
217 {
218 std::swap (bb1, bb2);
219 std::swap (e1, e2);
220 }
221 else if (do_store_elim
222 && EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest)
223 {
224 basic_block bb3 = EDGE_SUCC (bb1, 0)->dest;
225
226 if (!single_succ_p (bb1)
227 || (EDGE_SUCC (bb1, 0)->flags & EDGE_FALLTHRU) == 0
228 || !single_succ_p (bb2)
229 || (EDGE_SUCC (bb2, 0)->flags & EDGE_FALLTHRU) == 0
230 || EDGE_COUNT (bb3->preds) != 2)
231 continue;
232 if (cond_if_else_store_replacement (bb1, bb2, bb3))
233 cfgchanged = true;
234 continue;
235 }
236 else if (do_hoist_loads
237 && EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest)
238 {
239 basic_block bb3 = EDGE_SUCC (bb1, 0)->dest;
240
241 if (!FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (cond_stmt)))
242 && single_succ_p (bb1)
243 && single_succ_p (bb2)
244 && single_pred_p (bb1)
245 && single_pred_p (bb2)
246 && EDGE_COUNT (bb->succs) == 2
247 && EDGE_COUNT (bb3->preds) == 2
248 /* If one edge or the other is dominant, a conditional move
249 is likely to perform worse than the well-predicted branch. */
250 && !predictable_edge_p (EDGE_SUCC (bb, 0))
251 && !predictable_edge_p (EDGE_SUCC (bb, 1)))
252 hoist_adjacent_loads (bb, bb1, bb2, bb3);
253 continue;
254 }
255 else
256 continue;
257
258 e1 = EDGE_SUCC (bb1, 0);
259
260 /* Make sure that bb1 is just a fall through. */
261 if (!single_succ_p (bb1)
262 || (e1->flags & EDGE_FALLTHRU) == 0)
263 continue;
264
265 /* Also make sure that bb1 only have one predecessor and that it
266 is bb. */
267 if (!single_pred_p (bb1)
268 || single_pred (bb1) != bb)
269 continue;
270
271 if (do_store_elim)
272 {
273 /* bb1 is the middle block, bb2 the join block, bb the split block,
274 e1 the fallthrough edge from bb1 to bb2. We can't do the
275 optimization if the join block has more than two predecessors. */
276 if (EDGE_COUNT (bb2->preds) > 2)
277 continue;
278 if (cond_store_replacement (bb1, bb2, e1, e2, nontrap))
279 cfgchanged = true;
280 }
281 else
282 {
283 gimple_seq phis = phi_nodes (bb2);
284 gimple_stmt_iterator gsi;
285 bool candorest = true;
286
287 /* Value replacement can work with more than one PHI
288 so try that first. */
289 for (gsi = gsi_start (phis); !gsi_end_p (gsi); gsi_next (&gsi))
290 {
291 phi = as_a <gphi *> (gsi_stmt (gsi));
292 arg0 = gimple_phi_arg_def (phi, e1->dest_idx);
293 arg1 = gimple_phi_arg_def (phi, e2->dest_idx);
294 if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1) == 2)
295 {
296 candorest = false;
297 cfgchanged = true;
298 break;
299 }
300 }
301
302 if (!candorest)
303 continue;
304
305 phi = single_non_singleton_phi_for_edges (phis, e1, e2);
306 if (!phi)
307 continue;
308
309 arg0 = gimple_phi_arg_def (phi, e1->dest_idx);
310 arg1 = gimple_phi_arg_def (phi, e2->dest_idx);
311
312 /* Something is wrong if we cannot find the arguments in the PHI
313 node. */
314 gcc_assert (arg0 != NULL_TREE && arg1 != NULL_TREE);
315
316 gphi *newphi = factor_out_conditional_conversion (e1, e2, phi,
317 arg0, arg1,
318 cond_stmt);
319 if (newphi != NULL)
320 {
321 phi = newphi;
322 /* factor_out_conditional_conversion may create a new PHI in
323 BB2 and eliminate an existing PHI in BB2. Recompute values
324 that may be affected by that change. */
325 arg0 = gimple_phi_arg_def (phi, e1->dest_idx);
326 arg1 = gimple_phi_arg_def (phi, e2->dest_idx);
327 gcc_assert (arg0 != NULL_TREE && arg1 != NULL_TREE);
328 }
329
330 /* Do the replacement of conditional if it can be done. */
331 if (conditional_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
332 cfgchanged = true;
333 else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
334 cfgchanged = true;
335 else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
336 cfgchanged = true;
337 }
338 }
339
340 free (bb_order);
341
342 if (do_store_elim)
343 delete nontrap;
344 /* If the CFG has changed, we should cleanup the CFG. */
345 if (cfgchanged && do_store_elim)
346 {
347 /* In cond-store replacement we have added some loads on edges
348 and new VOPS (as we moved the store, and created a load). */
349 gsi_commit_edge_inserts ();
350 return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals;
351 }
352 else if (cfgchanged)
353 return TODO_cleanup_cfg;
354 return 0;
355}
356
357/* Replace PHI node element whose edge is E in block BB with variable NEW.
358 Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
359 is known to have two edges, one of which must reach BB). */
360
361static void
362replace_phi_edge_with_variable (basic_block cond_block,
363 edge e, gimple *phi, tree new_tree)
364{
365 basic_block bb = gimple_bb (phi);
366 basic_block block_to_remove;
367 gimple_stmt_iterator gsi;
368
369 /* Change the PHI argument to new. */
370 SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new_tree);
371
372 /* Remove the empty basic block. */
373 if (EDGE_SUCC (cond_block, 0)->dest == bb)
374 {
375 EDGE_SUCC (cond_block, 0)->flags |= EDGE_FALLTHRU;
376 EDGE_SUCC (cond_block, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
377 EDGE_SUCC (cond_block, 0)->probability = profile_probability::always ();
378
379 block_to_remove = EDGE_SUCC (cond_block, 1)->dest;
380 }
381 else
382 {
383 EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU;
384 EDGE_SUCC (cond_block, 1)->flags
385 &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
386 EDGE_SUCC (cond_block, 1)->probability = profile_probability::always ();
387
388 block_to_remove = EDGE_SUCC (cond_block, 0)->dest;
389 }
390 delete_basic_block (block_to_remove);
391
392 /* Eliminate the COND_EXPR at the end of COND_BLOCK. */
393 gsi = gsi_last_bb (cond_block);
394 gsi_remove (&gsi, true);
395
396 if (dump_file && (dump_flags & TDF_DETAILS))
397 fprintf (dump_file,
398 "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
399 cond_block->index,
400 bb->index);
401}
402
403/* PR66726: Factor conversion out of COND_EXPR. If the arguments of the PHI
404 stmt are CONVERT_STMT, factor out the conversion and perform the conversion
405 to the result of PHI stmt. COND_STMT is the controlling predicate.
406 Return the newly-created PHI, if any. */
407
408static gphi *
409factor_out_conditional_conversion (edge e0, edge e1, gphi *phi,
410 tree arg0, tree arg1, gimple *cond_stmt)
411{
412 gimple *arg0_def_stmt = NULL, *arg1_def_stmt = NULL, *new_stmt;
413 tree new_arg0 = NULL_TREE, new_arg1 = NULL_TREE;
414 tree temp, result;
415 gphi *newphi;
416 gimple_stmt_iterator gsi, gsi_for_def;
417 source_location locus = gimple_location (phi);
418 enum tree_code convert_code;
419
420 /* Handle only PHI statements with two arguments. TODO: If all
421 other arguments to PHI are INTEGER_CST or if their defining
422 statement have the same unary operation, we can handle more
423 than two arguments too. */
424 if (gimple_phi_num_args (phi) != 2)
425 return NULL;
426
427 /* First canonicalize to simplify tests. */
428 if (TREE_CODE (arg0) != SSA_NAME)
429 {
430 std::swap (arg0, arg1);
431 std::swap (e0, e1);
432 }
433
434 if (TREE_CODE (arg0) != SSA_NAME
435 || (TREE_CODE (arg1) != SSA_NAME
436 && TREE_CODE (arg1) != INTEGER_CST))
437 return NULL;
438
439 /* Check if arg0 is an SSA_NAME and the stmt which defines arg0 is
440 a conversion. */
441 arg0_def_stmt = SSA_NAME_DEF_STMT (arg0);
442 if (!gimple_assign_cast_p (arg0_def_stmt))
443 return NULL;
444
445 /* Use the RHS as new_arg0. */
446 convert_code = gimple_assign_rhs_code (arg0_def_stmt);
447 new_arg0 = gimple_assign_rhs1 (arg0_def_stmt);
448 if (convert_code == VIEW_CONVERT_EXPR)
449 {
450 new_arg0 = TREE_OPERAND (new_arg0, 0);
451 if (!is_gimple_reg_type (TREE_TYPE (new_arg0)))
452 return NULL;
453 }
454
455 if (TREE_CODE (arg1) == SSA_NAME)
456 {
457 /* Check if arg1 is an SSA_NAME and the stmt which defines arg1
458 is a conversion. */
459 arg1_def_stmt = SSA_NAME_DEF_STMT (arg1);
460 if (!is_gimple_assign (arg1_def_stmt)
461 || gimple_assign_rhs_code (arg1_def_stmt) != convert_code)
462 return NULL;
463
464 /* Use the RHS as new_arg1. */
465 new_arg1 = gimple_assign_rhs1 (arg1_def_stmt);
466 if (convert_code == VIEW_CONVERT_EXPR)
467 new_arg1 = TREE_OPERAND (new_arg1, 0);
468 }
469 else
470 {
471 /* If arg1 is an INTEGER_CST, fold it to new type. */
472 if (INTEGRAL_TYPE_P (TREE_TYPE (new_arg0))
473 && int_fits_type_p (arg1, TREE_TYPE (new_arg0)))
474 {
475 if (gimple_assign_cast_p (arg0_def_stmt))
476 {
477 /* For the INTEGER_CST case, we are just moving the
478 conversion from one place to another, which can often
479 hurt as the conversion moves further away from the
480 statement that computes the value. So, perform this
481 only if new_arg0 is an operand of COND_STMT, or
482 if arg0_def_stmt is the only non-debug stmt in
483 its basic block, because then it is possible this
484 could enable further optimizations (minmax replacement
485 etc.). See PR71016. */
486 if (new_arg0 != gimple_cond_lhs (cond_stmt)
487 && new_arg0 != gimple_cond_rhs (cond_stmt)
488 && gimple_bb (arg0_def_stmt) == e0->src)
489 {
490 gsi = gsi_for_stmt (arg0_def_stmt);
491 gsi_prev_nondebug (&gsi);
492 if (!gsi_end_p (gsi))
493 return NULL;
494 gsi = gsi_for_stmt (arg0_def_stmt);
495 gsi_next_nondebug (&gsi);
496 if (!gsi_end_p (gsi))
497 return NULL;
498 }
499 new_arg1 = fold_convert (TREE_TYPE (new_arg0), arg1);
500 }
501 else
502 return NULL;
503 }
504 else
505 return NULL;
506 }
507
508 /* If arg0/arg1 have > 1 use, then this transformation actually increases
509 the number of expressions evaluated at runtime. */
510 if (!has_single_use (arg0)
511 || (arg1_def_stmt && !has_single_use (arg1)))
512 return NULL;
513
514 /* If types of new_arg0 and new_arg1 are different bailout. */
515 if (!types_compatible_p (TREE_TYPE (new_arg0), TREE_TYPE (new_arg1)))
516 return NULL;
517
518 /* Create a new PHI stmt. */
519 result = PHI_RESULT (phi);
520 temp = make_ssa_name (TREE_TYPE (new_arg0), NULL);
521 newphi = create_phi_node (temp, gimple_bb (phi));
522
523 if (dump_file && (dump_flags & TDF_DETAILS))
524 {
525 fprintf (dump_file, "PHI ");
526 print_generic_expr (dump_file, gimple_phi_result (phi));
527 fprintf (dump_file,
528 " changed to factor conversion out from COND_EXPR.\n");
529 fprintf (dump_file, "New stmt with CAST that defines ");
530 print_generic_expr (dump_file, result);
531 fprintf (dump_file, ".\n");
532 }
533
534 /* Remove the old cast(s) that has single use. */
535 gsi_for_def = gsi_for_stmt (arg0_def_stmt);
536 gsi_remove (&gsi_for_def, true);
537 release_defs (arg0_def_stmt);
538
539 if (arg1_def_stmt)
540 {
541 gsi_for_def = gsi_for_stmt (arg1_def_stmt);
542 gsi_remove (&gsi_for_def, true);
543 release_defs (arg1_def_stmt);
544 }
545
546 add_phi_arg (newphi, new_arg0, e0, locus);
547 add_phi_arg (newphi, new_arg1, e1, locus);
548
549 /* Create the conversion stmt and insert it. */
550 if (convert_code == VIEW_CONVERT_EXPR)
551 temp = fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (result), temp);
552 new_stmt = gimple_build_assign (result, convert_code, temp);
553 gsi = gsi_after_labels (gimple_bb (phi));
554 gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
555
556 /* Remove the original PHI stmt. */
557 gsi = gsi_for_stmt (phi);
558 gsi_remove (&gsi, true);
559 return newphi;
560}
561
562/* The function conditional_replacement does the main work of doing the
563 conditional replacement. Return true if the replacement is done.
564 Otherwise return false.
565 BB is the basic block where the replacement is going to be done on. ARG0
566 is argument 0 from PHI. Likewise for ARG1. */
567
568static bool
569conditional_replacement (basic_block cond_bb, basic_block middle_bb,
570 edge e0, edge e1, gphi *phi,
571 tree arg0, tree arg1)
572{
573 tree result;
574 gimple *stmt;
575 gassign *new_stmt;
576 tree cond;
577 gimple_stmt_iterator gsi;
578 edge true_edge, false_edge;
579 tree new_var, new_var2;
580 bool neg;
581
582 /* FIXME: Gimplification of complex type is too hard for now. */
583 /* We aren't prepared to handle vectors either (and it is a question
584 if it would be worthwhile anyway). */
585 if (!(INTEGRAL_TYPE_P (TREE_TYPE (arg0))
586 || POINTER_TYPE_P (TREE_TYPE (arg0)))
587 || !(INTEGRAL_TYPE_P (TREE_TYPE (arg1))
588 || POINTER_TYPE_P (TREE_TYPE (arg1))))
589 return false;
590
591 /* The PHI arguments have the constants 0 and 1, or 0 and -1, then
592 convert it to the conditional. */
593 if ((integer_zerop (arg0) && integer_onep (arg1))
594 || (integer_zerop (arg1) && integer_onep (arg0)))
595 neg = false;
596 else if ((integer_zerop (arg0) && integer_all_onesp (arg1))
597 || (integer_zerop (arg1) && integer_all_onesp (arg0)))
598 neg = true;
599 else
600 return false;
601
602 if (!empty_block_p (middle_bb))
603 return false;
604
605 /* At this point we know we have a GIMPLE_COND with two successors.
606 One successor is BB, the other successor is an empty block which
607 falls through into BB.
608
609 There is a single PHI node at the join point (BB) and its arguments
610 are constants (0, 1) or (0, -1).
611
612 So, given the condition COND, and the two PHI arguments, we can
613 rewrite this PHI into non-branching code:
614
615 dest = (COND) or dest = COND'
616
617 We use the condition as-is if the argument associated with the
618 true edge has the value one or the argument associated with the
619 false edge as the value zero. Note that those conditions are not
620 the same since only one of the outgoing edges from the GIMPLE_COND
621 will directly reach BB and thus be associated with an argument. */
622
623 stmt = last_stmt (cond_bb);
624 result = PHI_RESULT (phi);
625
626 /* To handle special cases like floating point comparison, it is easier and
627 less error-prone to build a tree and gimplify it on the fly though it is
628 less efficient. */
629 cond = fold_build2_loc (gimple_location (stmt),
630 gimple_cond_code (stmt), boolean_type_node,
631 gimple_cond_lhs (stmt), gimple_cond_rhs (stmt));
632
633 /* We need to know which is the true edge and which is the false
634 edge so that we know when to invert the condition below. */
635 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
636 if ((e0 == true_edge && integer_zerop (arg0))
637 || (e0 == false_edge && !integer_zerop (arg0))
638 || (e1 == true_edge && integer_zerop (arg1))
639 || (e1 == false_edge && !integer_zerop (arg1)))
640 cond = fold_build1_loc (gimple_location (stmt),
641 TRUTH_NOT_EXPR, TREE_TYPE (cond), cond);
642
643 if (neg)
644 {
645 cond = fold_convert_loc (gimple_location (stmt),
646 TREE_TYPE (result), cond);
647 cond = fold_build1_loc (gimple_location (stmt),
648 NEGATE_EXPR, TREE_TYPE (cond), cond);
649 }
650
651 /* Insert our new statements at the end of conditional block before the
652 COND_STMT. */
653 gsi = gsi_for_stmt (stmt);
654 new_var = force_gimple_operand_gsi (&gsi, cond, true, NULL, true,
655 GSI_SAME_STMT);
656
657 if (!useless_type_conversion_p (TREE_TYPE (result), TREE_TYPE (new_var)))
658 {
659 source_location locus_0, locus_1;
660
661 new_var2 = make_ssa_name (TREE_TYPE (result));
662 new_stmt = gimple_build_assign (new_var2, CONVERT_EXPR, new_var);
663 gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
664 new_var = new_var2;
665
666 /* Set the locus to the first argument, unless is doesn't have one. */
667 locus_0 = gimple_phi_arg_location (phi, 0);
668 locus_1 = gimple_phi_arg_location (phi, 1);
669 if (locus_0 == UNKNOWN_LOCATION)
670 locus_0 = locus_1;
671 gimple_set_location (new_stmt, locus_0);
672 }
673
674 replace_phi_edge_with_variable (cond_bb, e1, phi, new_var);
675
676 /* Note that we optimized this PHI. */
677 return true;
678}
679
680/* Update *ARG which is defined in STMT so that it contains the
681 computed value if that seems profitable. Return true if the
682 statement is made dead by that rewriting. */
683
684static bool
685jump_function_from_stmt (tree *arg, gimple *stmt)
686{
687 enum tree_code code = gimple_assign_rhs_code (stmt);
688 if (code == ADDR_EXPR)
689 {
690 /* For arg = &p->i transform it to p, if possible. */
691 tree rhs1 = gimple_assign_rhs1 (stmt);
692 HOST_WIDE_INT offset;
693 tree tem = get_addr_base_and_unit_offset (TREE_OPERAND (rhs1, 0),
694 &offset);
695 if (tem
696 && TREE_CODE (tem) == MEM_REF
697 && (mem_ref_offset (tem) + offset) == 0)
698 {
699 *arg = TREE_OPERAND (tem, 0);
700 return true;
701 }
702 }
703 /* TODO: Much like IPA-CP jump-functions we want to handle constant
704 additions symbolically here, and we'd need to update the comparison
705 code that compares the arg + cst tuples in our caller. For now the
706 code above exactly handles the VEC_BASE pattern from vec.h. */
707 return false;
708}
709
710/* RHS is a source argument in a BIT_AND_EXPR which feeds a conditional
711 of the form SSA_NAME NE 0.
712
713 If RHS is fed by a simple EQ_EXPR comparison of two values, see if
714 the two input values of the EQ_EXPR match arg0 and arg1.
715
716 If so update *code and return TRUE. Otherwise return FALSE. */
717
718static bool
719rhs_is_fed_for_value_replacement (const_tree arg0, const_tree arg1,
720 enum tree_code *code, const_tree rhs)
721{
722 /* Obviously if RHS is not an SSA_NAME, we can't look at the defining
723 statement. */
724 if (TREE_CODE (rhs) == SSA_NAME)
725 {
726 gimple *def1 = SSA_NAME_DEF_STMT (rhs);
727
728 /* Verify the defining statement has an EQ_EXPR on the RHS. */
729 if (is_gimple_assign (def1) && gimple_assign_rhs_code (def1) == EQ_EXPR)
730 {
731 /* Finally verify the source operands of the EQ_EXPR are equal
732 to arg0 and arg1. */
733 tree op0 = gimple_assign_rhs1 (def1);
734 tree op1 = gimple_assign_rhs2 (def1);
735 if ((operand_equal_for_phi_arg_p (arg0, op0)
736 && operand_equal_for_phi_arg_p (arg1, op1))
737 || (operand_equal_for_phi_arg_p (arg0, op1)
738 && operand_equal_for_phi_arg_p (arg1, op0)))
739 {
740 /* We will perform the optimization. */
741 *code = gimple_assign_rhs_code (def1);
742 return true;
743 }
744 }
745 }
746 return false;
747}
748
749/* Return TRUE if arg0/arg1 are equal to the rhs/lhs or lhs/rhs of COND.
750
751 Also return TRUE if arg0/arg1 are equal to the source arguments of a
752 an EQ comparison feeding a BIT_AND_EXPR which feeds COND.
753
754 Return FALSE otherwise. */
755
756static bool
757operand_equal_for_value_replacement (const_tree arg0, const_tree arg1,
758 enum tree_code *code, gimple *cond)
759{
760 gimple *def;
761 tree lhs = gimple_cond_lhs (cond);
762 tree rhs = gimple_cond_rhs (cond);
763
764 if ((operand_equal_for_phi_arg_p (arg0, lhs)
765 && operand_equal_for_phi_arg_p (arg1, rhs))
766 || (operand_equal_for_phi_arg_p (arg1, lhs)
767 && operand_equal_for_phi_arg_p (arg0, rhs)))
768 return true;
769
770 /* Now handle more complex case where we have an EQ comparison
771 which feeds a BIT_AND_EXPR which feeds COND.
772
773 First verify that COND is of the form SSA_NAME NE 0. */
774 if (*code != NE_EXPR || !integer_zerop (rhs)
775 || TREE_CODE (lhs) != SSA_NAME)
776 return false;
777
778 /* Now ensure that SSA_NAME is set by a BIT_AND_EXPR. */
779 def = SSA_NAME_DEF_STMT (lhs);
780 if (!is_gimple_assign (def) || gimple_assign_rhs_code (def) != BIT_AND_EXPR)
781 return false;
782
783 /* Now verify arg0/arg1 correspond to the source arguments of an
784 EQ comparison feeding the BIT_AND_EXPR. */
785
786 tree tmp = gimple_assign_rhs1 (def);
787 if (rhs_is_fed_for_value_replacement (arg0, arg1, code, tmp))
788 return true;
789
790 tmp = gimple_assign_rhs2 (def);
791 if (rhs_is_fed_for_value_replacement (arg0, arg1, code, tmp))
792 return true;
793
794 return false;
795}
796
797/* Returns true if ARG is a neutral element for operation CODE
798 on the RIGHT side. */
799
800static bool
801neutral_element_p (tree_code code, tree arg, bool right)
802{
803 switch (code)
804 {
805 case PLUS_EXPR:
806 case BIT_IOR_EXPR:
807 case BIT_XOR_EXPR:
808 return integer_zerop (arg);
809
810 case LROTATE_EXPR:
811 case RROTATE_EXPR:
812 case LSHIFT_EXPR:
813 case RSHIFT_EXPR:
814 case MINUS_EXPR:
815 case POINTER_PLUS_EXPR:
816 return right && integer_zerop (arg);
817
818 case MULT_EXPR:
819 return integer_onep (arg);
820
821 case TRUNC_DIV_EXPR:
822 case CEIL_DIV_EXPR:
823 case FLOOR_DIV_EXPR:
824 case ROUND_DIV_EXPR:
825 case EXACT_DIV_EXPR:
826 return right && integer_onep (arg);
827
828 case BIT_AND_EXPR:
829 return integer_all_onesp (arg);
830
831 default:
832 return false;
833 }
834}
835
836/* Returns true if ARG is an absorbing element for operation CODE. */
837
838static bool
839absorbing_element_p (tree_code code, tree arg, bool right, tree rval)
840{
841 switch (code)
842 {
843 case BIT_IOR_EXPR:
844 return integer_all_onesp (arg);
845
846 case MULT_EXPR:
847 case BIT_AND_EXPR:
848 return integer_zerop (arg);
849
850 case LSHIFT_EXPR:
851 case RSHIFT_EXPR:
852 case LROTATE_EXPR:
853 case RROTATE_EXPR:
854 return !right && integer_zerop (arg);
855
856 case TRUNC_DIV_EXPR:
857 case CEIL_DIV_EXPR:
858 case FLOOR_DIV_EXPR:
859 case ROUND_DIV_EXPR:
860 case EXACT_DIV_EXPR:
861 case TRUNC_MOD_EXPR:
862 case CEIL_MOD_EXPR:
863 case FLOOR_MOD_EXPR:
864 case ROUND_MOD_EXPR:
865 return (!right
866 && integer_zerop (arg)
867 && tree_single_nonzero_warnv_p (rval, NULL));
868
869 default:
870 return false;
871 }
872}
873
874/* The function value_replacement does the main work of doing the value
875 replacement. Return non-zero if the replacement is done. Otherwise return
876 0. If we remove the middle basic block, return 2.
877 BB is the basic block where the replacement is going to be done on. ARG0
878 is argument 0 from the PHI. Likewise for ARG1. */
879
880static int
881value_replacement (basic_block cond_bb, basic_block middle_bb,
882 edge e0, edge e1, gimple *phi,
883 tree arg0, tree arg1)
884{
885 gimple_stmt_iterator gsi;
886 gimple *cond;
887 edge true_edge, false_edge;
888 enum tree_code code;
889 bool emtpy_or_with_defined_p = true;
890
891 /* If the type says honor signed zeros we cannot do this
892 optimization. */
893 if (HONOR_SIGNED_ZEROS (arg1))
894 return 0;
895
896 /* If there is a statement in MIDDLE_BB that defines one of the PHI
897 arguments, then adjust arg0 or arg1. */
898 gsi = gsi_start_nondebug_after_labels_bb (middle_bb);
899 while (!gsi_end_p (gsi))
900 {
901 gimple *stmt = gsi_stmt (gsi);
902 tree lhs;
903 gsi_next_nondebug (&gsi);
904 if (!is_gimple_assign (stmt))
905 {
906 emtpy_or_with_defined_p = false;
907 continue;
908 }
909 /* Now try to adjust arg0 or arg1 according to the computation
910 in the statement. */
911 lhs = gimple_assign_lhs (stmt);
912 if (!(lhs == arg0
913 && jump_function_from_stmt (&arg0, stmt))
914 || (lhs == arg1
915 && jump_function_from_stmt (&arg1, stmt)))
916 emtpy_or_with_defined_p = false;
917 }
918
919 cond = last_stmt (cond_bb);
920 code = gimple_cond_code (cond);
921
922 /* This transformation is only valid for equality comparisons. */
923 if (code != NE_EXPR && code != EQ_EXPR)
924 return 0;
925
926 /* We need to know which is the true edge and which is the false
927 edge so that we know if have abs or negative abs. */
928 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
929
930 /* At this point we know we have a COND_EXPR with two successors.
931 One successor is BB, the other successor is an empty block which
932 falls through into BB.
933
934 The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR.
935
936 There is a single PHI node at the join point (BB) with two arguments.
937
938 We now need to verify that the two arguments in the PHI node match
939 the two arguments to the equality comparison. */
940
941 if (operand_equal_for_value_replacement (arg0, arg1, &code, cond))
942 {
943 edge e;
944 tree arg;
945
946 /* For NE_EXPR, we want to build an assignment result = arg where
947 arg is the PHI argument associated with the true edge. For
948 EQ_EXPR we want the PHI argument associated with the false edge. */
949 e = (code == NE_EXPR ? true_edge : false_edge);
950
951 /* Unfortunately, E may not reach BB (it may instead have gone to
952 OTHER_BLOCK). If that is the case, then we want the single outgoing
953 edge from OTHER_BLOCK which reaches BB and represents the desired
954 path from COND_BLOCK. */
955 if (e->dest == middle_bb)
956 e = single_succ_edge (e->dest);
957
958 /* Now we know the incoming edge to BB that has the argument for the
959 RHS of our new assignment statement. */
960 if (e0 == e)
961 arg = arg0;
962 else
963 arg = arg1;
964
965 /* If the middle basic block was empty or is defining the
966 PHI arguments and this is a single phi where the args are different
967 for the edges e0 and e1 then we can remove the middle basic block. */
968 if (emtpy_or_with_defined_p
969 && single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi)),
970 e0, e1) == phi)
971 {
972 replace_phi_edge_with_variable (cond_bb, e1, phi, arg);
973 /* Note that we optimized this PHI. */
974 return 2;
975 }
976 else
977 {
978 /* Replace the PHI arguments with arg. */
979 SET_PHI_ARG_DEF (phi, e0->dest_idx, arg);
980 SET_PHI_ARG_DEF (phi, e1->dest_idx, arg);
981 if (dump_file && (dump_flags & TDF_DETAILS))
982 {
983 fprintf (dump_file, "PHI ");
984 print_generic_expr (dump_file, gimple_phi_result (phi));
985 fprintf (dump_file, " reduced for COND_EXPR in block %d to ",
986 cond_bb->index);
987 print_generic_expr (dump_file, arg);
988 fprintf (dump_file, ".\n");
989 }
990 return 1;
991 }
992
993 }
994
995 /* Now optimize (x != 0) ? x + y : y to just x + y. */
996 gsi = gsi_last_nondebug_bb (middle_bb);
997 if (gsi_end_p (gsi))
998 return 0;
999
1000 gimple *assign = gsi_stmt (gsi);
1001 if (!is_gimple_assign (assign)
1002 || gimple_assign_rhs_class (assign) != GIMPLE_BINARY_RHS
1003 || (!INTEGRAL_TYPE_P (TREE_TYPE (arg0))
1004 && !POINTER_TYPE_P (TREE_TYPE (arg0))))
1005 return 0;
1006
1007 /* Punt if there are (degenerate) PHIs in middle_bb, there should not be. */
1008 if (!gimple_seq_empty_p (phi_nodes (middle_bb)))
1009 return 0;
1010
1011 /* Allow up to 2 cheap preparation statements that prepare argument
1012 for assign, e.g.:
1013 if (y_4 != 0)
1014 goto <bb 3>;
1015 else
1016 goto <bb 4>;
1017 <bb 3>:
1018 _1 = (int) y_4;
1019 iftmp.0_6 = x_5(D) r<< _1;
1020 <bb 4>:
1021 # iftmp.0_2 = PHI <iftmp.0_6(3), x_5(D)(2)>
1022 or:
1023 if (y_3(D) == 0)
1024 goto <bb 4>;
1025 else
1026 goto <bb 3>;
1027 <bb 3>:
1028 y_4 = y_3(D) & 31;
1029 _1 = (int) y_4;
1030 _6 = x_5(D) r<< _1;
1031 <bb 4>:
1032 # _2 = PHI <x_5(D)(2), _6(3)> */
1033 gimple *prep_stmt[2] = { NULL, NULL };
1034 int prep_cnt;
1035 for (prep_cnt = 0; ; prep_cnt++)
1036 {
1037 gsi_prev_nondebug (&gsi);
1038 if (gsi_end_p (gsi))
1039 break;
1040
1041 gimple *g = gsi_stmt (gsi);
1042 if (gimple_code (g) == GIMPLE_LABEL)
1043 break;
1044
1045 if (prep_cnt == 2 || !is_gimple_assign (g))
1046 return 0;
1047
1048 tree lhs = gimple_assign_lhs (g);
1049 tree rhs1 = gimple_assign_rhs1 (g);
1050 use_operand_p use_p;
1051 gimple *use_stmt;
1052 if (TREE_CODE (lhs) != SSA_NAME
1053 || TREE_CODE (rhs1) != SSA_NAME
1054 || !INTEGRAL_TYPE_P (TREE_TYPE (lhs))
1055 || !INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
1056 || !single_imm_use (lhs, &use_p, &use_stmt)
1057 || use_stmt != (prep_cnt ? prep_stmt[prep_cnt - 1] : assign))
1058 return 0;
1059 switch (gimple_assign_rhs_code (g))
1060 {
1061 CASE_CONVERT:
1062 break;
1063 case PLUS_EXPR:
1064 case BIT_AND_EXPR:
1065 case BIT_IOR_EXPR:
1066 case BIT_XOR_EXPR:
1067 if (TREE_CODE (gimple_assign_rhs2 (g)) != INTEGER_CST)
1068 return 0;
1069 break;
1070 default:
1071 return 0;
1072 }
1073 prep_stmt[prep_cnt] = g;
1074 }
1075
1076 /* Only transform if it removes the condition. */
1077 if (!single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi)), e0, e1))
1078 return 0;
1079
1080 /* Size-wise, this is always profitable. */
1081 if (optimize_bb_for_speed_p (cond_bb)
1082 /* The special case is useless if it has a low probability. */
1083 && profile_status_for_fn (cfun) != PROFILE_ABSENT
1084 && EDGE_PRED (middle_bb, 0)->probability < profile_probability::even ()
1085 /* If assign is cheap, there is no point avoiding it. */
1086 && estimate_num_insns (bb_seq (middle_bb), &eni_time_weights)
1087 >= 3 * estimate_num_insns (cond, &eni_time_weights))
1088 return 0;
1089
1090 tree lhs = gimple_assign_lhs (assign);
1091 tree rhs1 = gimple_assign_rhs1 (assign);
1092 tree rhs2 = gimple_assign_rhs2 (assign);
1093 enum tree_code code_def = gimple_assign_rhs_code (assign);
1094 tree cond_lhs = gimple_cond_lhs (cond);
1095 tree cond_rhs = gimple_cond_rhs (cond);
1096
1097 /* Propagate the cond_rhs constant through preparation stmts,
1098 make sure UB isn't invoked while doing that. */
1099 for (int i = prep_cnt - 1; i >= 0; --i)
1100 {
1101 gimple *g = prep_stmt[i];
1102 tree grhs1 = gimple_assign_rhs1 (g);
1103 if (!operand_equal_for_phi_arg_p (cond_lhs, grhs1))
1104 return 0;
1105 cond_lhs = gimple_assign_lhs (g);
1106 cond_rhs = fold_convert (TREE_TYPE (grhs1), cond_rhs);
1107 if (TREE_CODE (cond_rhs) != INTEGER_CST
1108 || TREE_OVERFLOW (cond_rhs))
1109 return 0;
1110 if (gimple_assign_rhs_class (g) == GIMPLE_BINARY_RHS)
1111 {
1112 cond_rhs = int_const_binop (gimple_assign_rhs_code (g), cond_rhs,
1113 gimple_assign_rhs2 (g));
1114 if (TREE_OVERFLOW (cond_rhs))
1115 return 0;
1116 }
1117 cond_rhs = fold_convert (TREE_TYPE (cond_lhs), cond_rhs);
1118 if (TREE_CODE (cond_rhs) != INTEGER_CST
1119 || TREE_OVERFLOW (cond_rhs))
1120 return 0;
1121 }
1122
1123 if (((code == NE_EXPR && e1 == false_edge)
1124 || (code == EQ_EXPR && e1 == true_edge))
1125 && arg0 == lhs
1126 && ((arg1 == rhs1
1127 && operand_equal_for_phi_arg_p (rhs2, cond_lhs)
1128 && neutral_element_p (code_def, cond_rhs, true))
1129 || (arg1 == rhs2
1130 && operand_equal_for_phi_arg_p (rhs1, cond_lhs)
1131 && neutral_element_p (code_def, cond_rhs, false))
1132 || (operand_equal_for_phi_arg_p (arg1, cond_rhs)
1133 && ((operand_equal_for_phi_arg_p (rhs2, cond_lhs)
1134 && absorbing_element_p (code_def, cond_rhs, true, rhs2))
1135 || (operand_equal_for_phi_arg_p (rhs1, cond_lhs)
1136 && absorbing_element_p (code_def,
1137 cond_rhs, false, rhs2))))))
1138 {
1139 gsi = gsi_for_stmt (cond);
1140 /* Moving ASSIGN might change VR of lhs, e.g. when moving u_6
1141 def-stmt in:
1142 if (n_5 != 0)
1143 goto <bb 3>;
1144 else
1145 goto <bb 4>;
1146
1147 <bb 3>:
1148 # RANGE [0, 4294967294]
1149 u_6 = n_5 + 4294967295;
1150
1151 <bb 4>:
1152 # u_3 = PHI <u_6(3), 4294967295(2)> */
1153 reset_flow_sensitive_info (lhs);
1154 if (INTEGRAL_TYPE_P (TREE_TYPE (lhs)))
1155 {
1156 /* If available, we can use VR of phi result at least. */
1157 tree phires = gimple_phi_result (phi);
1158 struct range_info_def *phires_range_info
1159 = SSA_NAME_RANGE_INFO (phires);
1160 if (phires_range_info)
1161 duplicate_ssa_name_range_info (lhs, SSA_NAME_RANGE_TYPE (phires),
1162 phires_range_info);
1163 }
1164 gimple_stmt_iterator gsi_from;
1165 for (int i = prep_cnt - 1; i >= 0; --i)
1166 {
1167 tree plhs = gimple_assign_lhs (prep_stmt[i]);
1168 reset_flow_sensitive_info (plhs);
1169 gsi_from = gsi_for_stmt (prep_stmt[i]);
1170 gsi_move_before (&gsi_from, &gsi);
1171 }
1172 gsi_from = gsi_for_stmt (assign);
1173 gsi_move_before (&gsi_from, &gsi);
1174 replace_phi_edge_with_variable (cond_bb, e1, phi, lhs);
1175 return 2;
1176 }
1177
1178 return 0;
1179}
1180
1181/* The function minmax_replacement does the main work of doing the minmax
1182 replacement. Return true if the replacement is done. Otherwise return
1183 false.
1184 BB is the basic block where the replacement is going to be done on. ARG0
1185 is argument 0 from the PHI. Likewise for ARG1. */
1186
1187static bool
1188minmax_replacement (basic_block cond_bb, basic_block middle_bb,
1189 edge e0, edge e1, gimple *phi,
1190 tree arg0, tree arg1)
1191{
1192 tree result, type;
1193 gcond *cond;
1194 gassign *new_stmt;
1195 edge true_edge, false_edge;
1196 enum tree_code cmp, minmax, ass_code;
1197 tree smaller, alt_smaller, larger, alt_larger, arg_true, arg_false;
1198 gimple_stmt_iterator gsi, gsi_from;
1199
1200 type = TREE_TYPE (PHI_RESULT (phi));
1201
1202 /* The optimization may be unsafe due to NaNs. */
1203 if (HONOR_NANS (type) || HONOR_SIGNED_ZEROS (type))
1204 return false;
1205
1206 cond = as_a <gcond *> (last_stmt (cond_bb));
1207 cmp = gimple_cond_code (cond);
1208
1209 /* This transformation is only valid for order comparisons. Record which
1210 operand is smaller/larger if the result of the comparison is true. */
1211 alt_smaller = NULL_TREE;
1212 alt_larger = NULL_TREE;
1213 if (cmp == LT_EXPR || cmp == LE_EXPR)
1214 {
1215 smaller = gimple_cond_lhs (cond);
1216 larger = gimple_cond_rhs (cond);
1217 /* If we have smaller < CST it is equivalent to smaller <= CST-1.
1218 Likewise smaller <= CST is equivalent to smaller < CST+1. */
1219 if (TREE_CODE (larger) == INTEGER_CST)
1220 {
1221 if (cmp == LT_EXPR)
1222 {
1223 bool overflow;
1224 wide_int alt = wi::sub (wi::to_wide (larger), 1,
1225 TYPE_SIGN (TREE_TYPE (larger)),
1226 &overflow);
1227 if (! overflow)
1228 alt_larger = wide_int_to_tree (TREE_TYPE (larger), alt);
1229 }
1230 else
1231 {
1232 bool overflow;
1233 wide_int alt = wi::add (wi::to_wide (larger), 1,
1234 TYPE_SIGN (TREE_TYPE (larger)),
1235 &overflow);
1236 if (! overflow)
1237 alt_larger = wide_int_to_tree (TREE_TYPE (larger), alt);
1238 }
1239 }
1240 }
1241 else if (cmp == GT_EXPR || cmp == GE_EXPR)
1242 {
1243 smaller = gimple_cond_rhs (cond);
1244 larger = gimple_cond_lhs (cond);
1245 /* If we have larger > CST it is equivalent to larger >= CST+1.
1246 Likewise larger >= CST is equivalent to larger > CST-1. */
1247 if (TREE_CODE (smaller) == INTEGER_CST)
1248 {
1249 if (cmp == GT_EXPR)
1250 {
1251 bool overflow;
1252 wide_int alt = wi::add (wi::to_wide (smaller), 1,
1253 TYPE_SIGN (TREE_TYPE (smaller)),
1254 &overflow);
1255 if (! overflow)
1256 alt_smaller = wide_int_to_tree (TREE_TYPE (smaller), alt);
1257 }
1258 else
1259 {
1260 bool overflow;
1261 wide_int alt = wi::sub (wi::to_wide (smaller), 1,
1262 TYPE_SIGN (TREE_TYPE (smaller)),
1263 &overflow);
1264 if (! overflow)
1265 alt_smaller = wide_int_to_tree (TREE_TYPE (smaller), alt);
1266 }
1267 }
1268 }
1269 else
1270 return false;
1271
1272 /* We need to know which is the true edge and which is the false
1273 edge so that we know if have abs or negative abs. */
1274 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
1275
1276 /* Forward the edges over the middle basic block. */
1277 if (true_edge->dest == middle_bb)
1278 true_edge = EDGE_SUCC (true_edge->dest, 0);
1279 if (false_edge->dest == middle_bb)
1280 false_edge = EDGE_SUCC (false_edge->dest, 0);
1281
1282 if (true_edge == e0)
1283 {
1284 gcc_assert (false_edge == e1);
1285 arg_true = arg0;
1286 arg_false = arg1;
1287 }
1288 else
1289 {
1290 gcc_assert (false_edge == e0);
1291 gcc_assert (true_edge == e1);
1292 arg_true = arg1;
1293 arg_false = arg0;
1294 }
1295
1296 if (empty_block_p (middle_bb))
1297 {
1298 if ((operand_equal_for_phi_arg_p (arg_true, smaller)
1299 || (alt_smaller
1300 && operand_equal_for_phi_arg_p (arg_true, alt_smaller)))
1301 && (operand_equal_for_phi_arg_p (arg_false, larger)
1302 || (alt_larger
1303 && operand_equal_for_phi_arg_p (arg_true, alt_larger))))
1304 {
1305 /* Case
1306
1307 if (smaller < larger)
1308 rslt = smaller;
1309 else
1310 rslt = larger; */
1311 minmax = MIN_EXPR;
1312 }
1313 else if ((operand_equal_for_phi_arg_p (arg_false, smaller)
1314 || (alt_smaller
1315 && operand_equal_for_phi_arg_p (arg_false, alt_smaller)))
1316 && (operand_equal_for_phi_arg_p (arg_true, larger)
1317 || (alt_larger
1318 && operand_equal_for_phi_arg_p (arg_true, alt_larger))))
1319 minmax = MAX_EXPR;
1320 else
1321 return false;
1322 }
1323 else
1324 {
1325 /* Recognize the following case, assuming d <= u:
1326
1327 if (a <= u)
1328 b = MAX (a, d);
1329 x = PHI <b, u>
1330
1331 This is equivalent to
1332
1333 b = MAX (a, d);
1334 x = MIN (b, u); */
1335
1336 gimple *assign = last_and_only_stmt (middle_bb);
1337 tree lhs, op0, op1, bound;
1338
1339 if (!assign
1340 || gimple_code (assign) != GIMPLE_ASSIGN)
1341 return false;
1342
1343 lhs = gimple_assign_lhs (assign);
1344 ass_code = gimple_assign_rhs_code (assign);
1345 if (ass_code != MAX_EXPR && ass_code != MIN_EXPR)
1346 return false;
1347 op0 = gimple_assign_rhs1 (assign);
1348 op1 = gimple_assign_rhs2 (assign);
1349
1350 if (true_edge->src == middle_bb)
1351 {
1352 /* We got here if the condition is true, i.e., SMALLER < LARGER. */
1353 if (!operand_equal_for_phi_arg_p (lhs, arg_true))
1354 return false;
1355
1356 if (operand_equal_for_phi_arg_p (arg_false, larger)
1357 || (alt_larger
1358 && operand_equal_for_phi_arg_p (arg_false, alt_larger)))
1359 {
1360 /* Case
1361
1362 if (smaller < larger)
1363 {
1364 r' = MAX_EXPR (smaller, bound)
1365 }
1366 r = PHI <r', larger> --> to be turned to MIN_EXPR. */
1367 if (ass_code != MAX_EXPR)
1368 return false;
1369
1370 minmax = MIN_EXPR;
1371 if (operand_equal_for_phi_arg_p (op0, smaller)
1372 || (alt_smaller
1373 && operand_equal_for_phi_arg_p (op0, alt_smaller)))
1374 bound = op1;
1375 else if (operand_equal_for_phi_arg_p (op1, smaller)
1376 || (alt_smaller
1377 && operand_equal_for_phi_arg_p (op1, alt_smaller)))
1378 bound = op0;
1379 else
1380 return false;
1381
1382 /* We need BOUND <= LARGER. */
1383 if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node,
1384 bound, larger)))
1385 return false;
1386 }
1387 else if (operand_equal_for_phi_arg_p (arg_false, smaller)
1388 || (alt_smaller
1389 && operand_equal_for_phi_arg_p (arg_false, alt_smaller)))
1390 {
1391 /* Case
1392
1393 if (smaller < larger)
1394 {
1395 r' = MIN_EXPR (larger, bound)
1396 }
1397 r = PHI <r', smaller> --> to be turned to MAX_EXPR. */
1398 if (ass_code != MIN_EXPR)
1399 return false;
1400
1401 minmax = MAX_EXPR;
1402 if (operand_equal_for_phi_arg_p (op0, larger)
1403 || (alt_larger
1404 && operand_equal_for_phi_arg_p (op0, alt_larger)))
1405 bound = op1;
1406 else if (operand_equal_for_phi_arg_p (op1, larger)
1407 || (alt_larger
1408 && operand_equal_for_phi_arg_p (op1, alt_larger)))
1409 bound = op0;
1410 else
1411 return false;
1412
1413 /* We need BOUND >= SMALLER. */
1414 if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node,
1415 bound, smaller)))
1416 return false;
1417 }
1418 else
1419 return false;
1420 }
1421 else
1422 {
1423 /* We got here if the condition is false, i.e., SMALLER > LARGER. */
1424 if (!operand_equal_for_phi_arg_p (lhs, arg_false))
1425 return false;
1426
1427 if (operand_equal_for_phi_arg_p (arg_true, larger)
1428 || (alt_larger
1429 && operand_equal_for_phi_arg_p (arg_true, alt_larger)))
1430 {
1431 /* Case
1432
1433 if (smaller > larger)
1434 {
1435 r' = MIN_EXPR (smaller, bound)
1436 }
1437 r = PHI <r', larger> --> to be turned to MAX_EXPR. */
1438 if (ass_code != MIN_EXPR)
1439 return false;
1440
1441 minmax = MAX_EXPR;
1442 if (operand_equal_for_phi_arg_p (op0, smaller)
1443 || (alt_smaller
1444 && operand_equal_for_phi_arg_p (op0, alt_smaller)))
1445 bound = op1;
1446 else if (operand_equal_for_phi_arg_p (op1, smaller)
1447 || (alt_smaller
1448 && operand_equal_for_phi_arg_p (op1, alt_smaller)))
1449 bound = op0;
1450 else
1451 return false;
1452
1453 /* We need BOUND >= LARGER. */
1454 if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node,
1455 bound, larger)))
1456 return false;
1457 }
1458 else if (operand_equal_for_phi_arg_p (arg_true, smaller)
1459 || (alt_smaller
1460 && operand_equal_for_phi_arg_p (arg_true, alt_smaller)))
1461 {
1462 /* Case
1463
1464 if (smaller > larger)
1465 {
1466 r' = MAX_EXPR (larger, bound)
1467 }
1468 r = PHI <r', smaller> --> to be turned to MIN_EXPR. */
1469 if (ass_code != MAX_EXPR)
1470 return false;
1471
1472 minmax = MIN_EXPR;
1473 if (operand_equal_for_phi_arg_p (op0, larger))
1474 bound = op1;
1475 else if (operand_equal_for_phi_arg_p (op1, larger))
1476 bound = op0;
1477 else
1478 return false;
1479
1480 /* We need BOUND <= SMALLER. */
1481 if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node,
1482 bound, smaller)))
1483 return false;
1484 }
1485 else
1486 return false;
1487 }
1488
1489 /* Move the statement from the middle block. */
1490 gsi = gsi_last_bb (cond_bb);
1491 gsi_from = gsi_last_nondebug_bb (middle_bb);
1492 reset_flow_sensitive_info (SINGLE_SSA_TREE_OPERAND (gsi_stmt (gsi_from),
1493 SSA_OP_DEF));
1494 gsi_move_before (&gsi_from, &gsi);
1495 }
1496
1497 /* Create an SSA var to hold the min/max result. If we're the only
1498 things setting the target PHI, then we can clone the PHI
1499 variable. Otherwise we must create a new one. */
1500 result = PHI_RESULT (phi);
1501 if (EDGE_COUNT (gimple_bb (phi)->preds) == 2)
1502 result = duplicate_ssa_name (result, NULL);
1503 else
1504 result = make_ssa_name (TREE_TYPE (result));
1505
1506 /* Emit the statement to compute min/max. */
1507 new_stmt = gimple_build_assign (result, minmax, arg0, arg1);
1508 gsi = gsi_last_bb (cond_bb);
1509 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
1510
1511 replace_phi_edge_with_variable (cond_bb, e1, phi, result);
1512
1513 return true;
1514}
1515
1516/* The function absolute_replacement does the main work of doing the absolute
1517 replacement. Return true if the replacement is done. Otherwise return
1518 false.
1519 bb is the basic block where the replacement is going to be done on. arg0
1520 is argument 0 from the phi. Likewise for arg1. */
1521
1522static bool
1523abs_replacement (basic_block cond_bb, basic_block middle_bb,
1524 edge e0 ATTRIBUTE_UNUSED, edge e1,
1525 gimple *phi, tree arg0, tree arg1)
1526{
1527 tree result;
1528 gassign *new_stmt;
1529 gimple *cond;
1530 gimple_stmt_iterator gsi;
1531 edge true_edge, false_edge;
1532 gimple *assign;
1533 edge e;
1534 tree rhs, lhs;
1535 bool negate;
1536 enum tree_code cond_code;
1537
1538 /* If the type says honor signed zeros we cannot do this
1539 optimization. */
1540 if (HONOR_SIGNED_ZEROS (arg1))
1541 return false;
1542
1543 /* OTHER_BLOCK must have only one executable statement which must have the
1544 form arg0 = -arg1 or arg1 = -arg0. */
1545
1546 assign = last_and_only_stmt (middle_bb);
1547 /* If we did not find the proper negation assignment, then we can not
1548 optimize. */
1549 if (assign == NULL)
1550 return false;
1551
1552 /* If we got here, then we have found the only executable statement
1553 in OTHER_BLOCK. If it is anything other than arg = -arg1 or
1554 arg1 = -arg0, then we can not optimize. */
1555 if (gimple_code (assign) != GIMPLE_ASSIGN)
1556 return false;
1557
1558 lhs = gimple_assign_lhs (assign);
1559
1560 if (gimple_assign_rhs_code (assign) != NEGATE_EXPR)
1561 return false;
1562
1563 rhs = gimple_assign_rhs1 (assign);
1564
1565 /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */
1566 if (!(lhs == arg0 && rhs == arg1)
1567 && !(lhs == arg1 && rhs == arg0))
1568 return false;
1569
1570 cond = last_stmt (cond_bb);
1571 result = PHI_RESULT (phi);
1572
1573 /* Only relationals comparing arg[01] against zero are interesting. */
1574 cond_code = gimple_cond_code (cond);
1575 if (cond_code != GT_EXPR && cond_code != GE_EXPR
1576 && cond_code != LT_EXPR && cond_code != LE_EXPR)
1577 return false;
1578
1579 /* Make sure the conditional is arg[01] OP y. */
1580 if (gimple_cond_lhs (cond) != rhs)
1581 return false;
1582
1583 if (FLOAT_TYPE_P (TREE_TYPE (gimple_cond_rhs (cond)))
1584 ? real_zerop (gimple_cond_rhs (cond))
1585 : integer_zerop (gimple_cond_rhs (cond)))
1586 ;
1587 else
1588 return false;
1589
1590 /* We need to know which is the true edge and which is the false
1591 edge so that we know if have abs or negative abs. */
1592 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
1593
1594 /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we
1595 will need to negate the result. Similarly for LT_EXPR/LE_EXPR if
1596 the false edge goes to OTHER_BLOCK. */
1597 if (cond_code == GT_EXPR || cond_code == GE_EXPR)
1598 e = true_edge;
1599 else
1600 e = false_edge;
1601
1602 if (e->dest == middle_bb)
1603 negate = true;
1604 else
1605 negate = false;
1606
1607 /* If the code negates only iff positive then make sure to not
1608 introduce undefined behavior when negating or computing the absolute.
1609 ??? We could use range info if present to check for arg1 == INT_MIN. */
1610 if (negate
1611 && (ANY_INTEGRAL_TYPE_P (TREE_TYPE (arg1))
1612 && ! TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg1))))
1613 return false;
1614
1615 result = duplicate_ssa_name (result, NULL);
1616
1617 if (negate)
1618 lhs = make_ssa_name (TREE_TYPE (result));
1619 else
1620 lhs = result;
1621
1622 /* Build the modify expression with abs expression. */
1623 new_stmt = gimple_build_assign (lhs, ABS_EXPR, rhs);
1624
1625 gsi = gsi_last_bb (cond_bb);
1626 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
1627
1628 if (negate)
1629 {
1630 /* Get the right GSI. We want to insert after the recently
1631 added ABS_EXPR statement (which we know is the first statement
1632 in the block. */
1633 new_stmt = gimple_build_assign (result, NEGATE_EXPR, lhs);
1634
1635 gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
1636 }
1637
1638 replace_phi_edge_with_variable (cond_bb, e1, phi, result);
1639
1640 /* Note that we optimized this PHI. */
1641 return true;
1642}
1643
1644/* Auxiliary functions to determine the set of memory accesses which
1645 can't trap because they are preceded by accesses to the same memory
1646 portion. We do that for MEM_REFs, so we only need to track
1647 the SSA_NAME of the pointer indirectly referenced. The algorithm
1648 simply is a walk over all instructions in dominator order. When
1649 we see an MEM_REF we determine if we've already seen a same
1650 ref anywhere up to the root of the dominator tree. If we do the
1651 current access can't trap. If we don't see any dominating access
1652 the current access might trap, but might also make later accesses
1653 non-trapping, so we remember it. We need to be careful with loads
1654 or stores, for instance a load might not trap, while a store would,
1655 so if we see a dominating read access this doesn't mean that a later
1656 write access would not trap. Hence we also need to differentiate the
1657 type of access(es) seen.
1658
1659 ??? We currently are very conservative and assume that a load might
1660 trap even if a store doesn't (write-only memory). This probably is
1661 overly conservative. */
1662
1663/* A hash-table of SSA_NAMEs, and in which basic block an MEM_REF
1664 through it was seen, which would constitute a no-trap region for
1665 same accesses. */
1666struct name_to_bb
1667{
1668 unsigned int ssa_name_ver;
1669 unsigned int phase;
1670 bool store;
1671 HOST_WIDE_INT offset, size;
1672 basic_block bb;
1673};
1674
1675/* Hashtable helpers. */
1676
1677struct ssa_names_hasher : free_ptr_hash <name_to_bb>
1678{
1679 static inline hashval_t hash (const name_to_bb *);
1680 static inline bool equal (const name_to_bb *, const name_to_bb *);
1681};
1682
1683/* Used for quick clearing of the hash-table when we see calls.
1684 Hash entries with phase < nt_call_phase are invalid. */
1685static unsigned int nt_call_phase;
1686
1687/* The hash function. */
1688
1689inline hashval_t
1690ssa_names_hasher::hash (const name_to_bb *n)
1691{
1692 return n->ssa_name_ver ^ (((hashval_t) n->store) << 31)
1693 ^ (n->offset << 6) ^ (n->size << 3);
1694}
1695
1696/* The equality function of *P1 and *P2. */
1697
1698inline bool
1699ssa_names_hasher::equal (const name_to_bb *n1, const name_to_bb *n2)
1700{
1701 return n1->ssa_name_ver == n2->ssa_name_ver
1702 && n1->store == n2->store
1703 && n1->offset == n2->offset
1704 && n1->size == n2->size;
1705}
1706
1707class nontrapping_dom_walker : public dom_walker
1708{
1709public:
1710 nontrapping_dom_walker (cdi_direction direction, hash_set<tree> *ps)
1711 : dom_walker (direction), m_nontrapping (ps), m_seen_ssa_names (128) {}
1712
1713 virtual edge before_dom_children (basic_block);
1714 virtual void after_dom_children (basic_block);
1715
1716private:
1717
1718 /* We see the expression EXP in basic block BB. If it's an interesting
1719 expression (an MEM_REF through an SSA_NAME) possibly insert the
1720 expression into the set NONTRAP or the hash table of seen expressions.
1721 STORE is true if this expression is on the LHS, otherwise it's on
1722 the RHS. */
1723 void add_or_mark_expr (basic_block, tree, bool);
1724
1725 hash_set<tree> *m_nontrapping;
1726
1727 /* The hash table for remembering what we've seen. */
1728 hash_table<ssa_names_hasher> m_seen_ssa_names;
1729};
1730
1731/* Called by walk_dominator_tree, when entering the block BB. */
1732edge
1733nontrapping_dom_walker::before_dom_children (basic_block bb)
1734{
1735 edge e;
1736 edge_iterator ei;
1737 gimple_stmt_iterator gsi;
1738
1739 /* If we haven't seen all our predecessors, clear the hash-table. */
1740 FOR_EACH_EDGE (e, ei, bb->preds)
1741 if ((((size_t)e->src->aux) & 2) == 0)
1742 {
1743 nt_call_phase++;
1744 break;
1745 }
1746
1747 /* Mark this BB as being on the path to dominator root and as visited. */
1748 bb->aux = (void*)(1 | 2);
1749
1750 /* And walk the statements in order. */
1751 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1752 {
1753 gimple *stmt = gsi_stmt (gsi);
1754
1755 if ((gimple_code (stmt) == GIMPLE_ASM && gimple_vdef (stmt))
1756 || (is_gimple_call (stmt)
1757 && (!nonfreeing_call_p (stmt) || !nonbarrier_call_p (stmt))))
1758 nt_call_phase++;
1759 else if (gimple_assign_single_p (stmt) && !gimple_has_volatile_ops (stmt))
1760 {
1761 add_or_mark_expr (bb, gimple_assign_lhs (stmt), true);
1762 add_or_mark_expr (bb, gimple_assign_rhs1 (stmt), false);
1763 }
1764 }
1765 return NULL;
1766}
1767
1768/* Called by walk_dominator_tree, when basic block BB is exited. */
1769void
1770nontrapping_dom_walker::after_dom_children (basic_block bb)
1771{
1772 /* This BB isn't on the path to dominator root anymore. */
1773 bb->aux = (void*)2;
1774}
1775
1776/* We see the expression EXP in basic block BB. If it's an interesting
1777 expression (an MEM_REF through an SSA_NAME) possibly insert the
1778 expression into the set NONTRAP or the hash table of seen expressions.
1779 STORE is true if this expression is on the LHS, otherwise it's on
1780 the RHS. */
1781void
1782nontrapping_dom_walker::add_or_mark_expr (basic_block bb, tree exp, bool store)
1783{
1784 HOST_WIDE_INT size;
1785
1786 if (TREE_CODE (exp) == MEM_REF
1787 && TREE_CODE (TREE_OPERAND (exp, 0)) == SSA_NAME
1788 && tree_fits_shwi_p (TREE_OPERAND (exp, 1))
1789 && (size = int_size_in_bytes (TREE_TYPE (exp))) > 0)
1790 {
1791 tree name = TREE_OPERAND (exp, 0);
1792 struct name_to_bb map;
1793 name_to_bb **slot;
1794 struct name_to_bb *n2bb;
1795 basic_block found_bb = 0;
1796
1797 /* Try to find the last seen MEM_REF through the same
1798 SSA_NAME, which can trap. */
1799 map.ssa_name_ver = SSA_NAME_VERSION (name);
1800 map.phase = 0;
1801 map.bb = 0;
1802 map.store = store;
1803 map.offset = tree_to_shwi (TREE_OPERAND (exp, 1));
1804 map.size = size;
1805
1806 slot = m_seen_ssa_names.find_slot (&map, INSERT);
1807 n2bb = *slot;
1808 if (n2bb && n2bb->phase >= nt_call_phase)
1809 found_bb = n2bb->bb;
1810
1811 /* If we've found a trapping MEM_REF, _and_ it dominates EXP
1812 (it's in a basic block on the path from us to the dominator root)
1813 then we can't trap. */
1814 if (found_bb && (((size_t)found_bb->aux) & 1) == 1)
1815 {
1816 m_nontrapping->add (exp);
1817 }
1818 else
1819 {
1820 /* EXP might trap, so insert it into the hash table. */
1821 if (n2bb)
1822 {
1823 n2bb->phase = nt_call_phase;
1824 n2bb->bb = bb;
1825 }
1826 else
1827 {
1828 n2bb = XNEW (struct name_to_bb);
1829 n2bb->ssa_name_ver = SSA_NAME_VERSION (name);
1830 n2bb->phase = nt_call_phase;
1831 n2bb->bb = bb;
1832 n2bb->store = store;
1833 n2bb->offset = map.offset;
1834 n2bb->size = size;
1835 *slot = n2bb;
1836 }
1837 }
1838 }
1839}
1840
1841/* This is the entry point of gathering non trapping memory accesses.
1842 It will do a dominator walk over the whole function, and it will
1843 make use of the bb->aux pointers. It returns a set of trees
1844 (the MEM_REFs itself) which can't trap. */
1845static hash_set<tree> *
1846get_non_trapping (void)
1847{
1848 nt_call_phase = 0;
1849 hash_set<tree> *nontrap = new hash_set<tree>;
1850 /* We're going to do a dominator walk, so ensure that we have
1851 dominance information. */
1852 calculate_dominance_info (CDI_DOMINATORS);
1853
1854 nontrapping_dom_walker (CDI_DOMINATORS, nontrap)
1855 .walk (cfun->cfg->x_entry_block_ptr);
1856
1857 clear_aux_for_blocks ();
1858 return nontrap;
1859}
1860
1861/* Do the main work of conditional store replacement. We already know
1862 that the recognized pattern looks like so:
1863
1864 split:
1865 if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)
1866 MIDDLE_BB:
1867 something
1868 fallthrough (edge E0)
1869 JOIN_BB:
1870 some more
1871
1872 We check that MIDDLE_BB contains only one store, that that store
1873 doesn't trap (not via NOTRAP, but via checking if an access to the same
1874 memory location dominates us) and that the store has a "simple" RHS. */
1875
1876static bool
1877cond_store_replacement (basic_block middle_bb, basic_block join_bb,
1878 edge e0, edge e1, hash_set<tree> *nontrap)
1879{
1880 gimple *assign = last_and_only_stmt (middle_bb);
1881 tree lhs, rhs, name, name2;
1882 gphi *newphi;
1883 gassign *new_stmt;
1884 gimple_stmt_iterator gsi;
1885 source_location locus;
1886
1887 /* Check if middle_bb contains of only one store. */
1888 if (!assign
1889 || !gimple_assign_single_p (assign)
1890 || gimple_has_volatile_ops (assign))
1891 return false;
1892
1893 locus = gimple_location (assign);
1894 lhs = gimple_assign_lhs (assign);
1895 rhs = gimple_assign_rhs1 (assign);
1896 if (TREE_CODE (lhs) != MEM_REF
1897 || TREE_CODE (TREE_OPERAND (lhs, 0)) != SSA_NAME
1898 || !is_gimple_reg_type (TREE_TYPE (lhs)))
1899 return false;
1900
1901 /* Prove that we can move the store down. We could also check
1902 TREE_THIS_NOTRAP here, but in that case we also could move stores,
1903 whose value is not available readily, which we want to avoid. */
1904 if (!nontrap->contains (lhs))
1905 return false;
1906
1907 /* Now we've checked the constraints, so do the transformation:
1908 1) Remove the single store. */
1909 gsi = gsi_for_stmt (assign);
1910 unlink_stmt_vdef (assign);
1911 gsi_remove (&gsi, true);
1912 release_defs (assign);
1913
1914 /* Make both store and load use alias-set zero as we have to
1915 deal with the case of the store being a conditional change
1916 of the dynamic type. */
1917 lhs = unshare_expr (lhs);
1918 tree *basep = &lhs;
1919 while (handled_component_p (*basep))
1920 basep = &TREE_OPERAND (*basep, 0);
1921 if (TREE_CODE (*basep) == MEM_REF
1922 || TREE_CODE (*basep) == TARGET_MEM_REF)
1923 TREE_OPERAND (*basep, 1)
1924 = fold_convert (ptr_type_node, TREE_OPERAND (*basep, 1));
1925 else
1926 *basep = build2 (MEM_REF, TREE_TYPE (*basep),
1927 build_fold_addr_expr (*basep),
1928 build_zero_cst (ptr_type_node));
1929
1930 /* 2) Insert a load from the memory of the store to the temporary
1931 on the edge which did not contain the store. */
1932 name = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
1933 new_stmt = gimple_build_assign (name, lhs);
1934 gimple_set_location (new_stmt, locus);
1935 gsi_insert_on_edge (e1, new_stmt);
1936
1937 /* 3) Create a PHI node at the join block, with one argument
1938 holding the old RHS, and the other holding the temporary
1939 where we stored the old memory contents. */
1940 name2 = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
1941 newphi = create_phi_node (name2, join_bb);
1942 add_phi_arg (newphi, rhs, e0, locus);
1943 add_phi_arg (newphi, name, e1, locus);
1944
1945 lhs = unshare_expr (lhs);
1946 new_stmt = gimple_build_assign (lhs, PHI_RESULT (newphi));
1947
1948 /* 4) Insert that PHI node. */
1949 gsi = gsi_after_labels (join_bb);
1950 if (gsi_end_p (gsi))
1951 {
1952 gsi = gsi_last_bb (join_bb);
1953 gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
1954 }
1955 else
1956 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
1957
1958 return true;
1959}
1960
1961/* Do the main work of conditional store replacement. */
1962
1963static bool
1964cond_if_else_store_replacement_1 (basic_block then_bb, basic_block else_bb,
1965 basic_block join_bb, gimple *then_assign,
1966 gimple *else_assign)
1967{
1968 tree lhs_base, lhs, then_rhs, else_rhs, name;
1969 source_location then_locus, else_locus;
1970 gimple_stmt_iterator gsi;
1971 gphi *newphi;
1972 gassign *new_stmt;
1973
1974 if (then_assign == NULL
1975 || !gimple_assign_single_p (then_assign)
1976 || gimple_clobber_p (then_assign)
1977 || gimple_has_volatile_ops (then_assign)
1978 || else_assign == NULL
1979 || !gimple_assign_single_p (else_assign)
1980 || gimple_clobber_p (else_assign)
1981 || gimple_has_volatile_ops (else_assign))
1982 return false;
1983
1984 lhs = gimple_assign_lhs (then_assign);
1985 if (!is_gimple_reg_type (TREE_TYPE (lhs))
1986 || !operand_equal_p (lhs, gimple_assign_lhs (else_assign), 0))
1987 return false;
1988
1989 lhs_base = get_base_address (lhs);
1990 if (lhs_base == NULL_TREE
1991 || (!DECL_P (lhs_base) && TREE_CODE (lhs_base) != MEM_REF))
1992 return false;
1993
1994 then_rhs = gimple_assign_rhs1 (then_assign);
1995 else_rhs = gimple_assign_rhs1 (else_assign);
1996 then_locus = gimple_location (then_assign);
1997 else_locus = gimple_location (else_assign);
1998
1999 /* Now we've checked the constraints, so do the transformation:
2000 1) Remove the stores. */
2001 gsi = gsi_for_stmt (then_assign);
2002 unlink_stmt_vdef (then_assign);
2003 gsi_remove (&gsi, true);
2004 release_defs (then_assign);
2005
2006 gsi = gsi_for_stmt (else_assign);
2007 unlink_stmt_vdef (else_assign);
2008 gsi_remove (&gsi, true);
2009 release_defs (else_assign);
2010
2011 /* 2) Create a PHI node at the join block, with one argument
2012 holding the old RHS, and the other holding the temporary
2013 where we stored the old memory contents. */
2014 name = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
2015 newphi = create_phi_node (name, join_bb);
2016 add_phi_arg (newphi, then_rhs, EDGE_SUCC (then_bb, 0), then_locus);
2017 add_phi_arg (newphi, else_rhs, EDGE_SUCC (else_bb, 0), else_locus);
2018
2019 new_stmt = gimple_build_assign (lhs, PHI_RESULT (newphi));
2020
2021 /* 3) Insert that PHI node. */
2022 gsi = gsi_after_labels (join_bb);
2023 if (gsi_end_p (gsi))
2024 {
2025 gsi = gsi_last_bb (join_bb);
2026 gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
2027 }
2028 else
2029 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
2030
2031 return true;
2032}
2033
2034/* Conditional store replacement. We already know
2035 that the recognized pattern looks like so:
2036
2037 split:
2038 if (cond) goto THEN_BB; else goto ELSE_BB (edge E1)
2039 THEN_BB:
2040 ...
2041 X = Y;
2042 ...
2043 goto JOIN_BB;
2044 ELSE_BB:
2045 ...
2046 X = Z;
2047 ...
2048 fallthrough (edge E0)
2049 JOIN_BB:
2050 some more
2051
2052 We check that it is safe to sink the store to JOIN_BB by verifying that
2053 there are no read-after-write or write-after-write dependencies in
2054 THEN_BB and ELSE_BB. */
2055
2056static bool
2057cond_if_else_store_replacement (basic_block then_bb, basic_block else_bb,
2058 basic_block join_bb)
2059{
2060 gimple *then_assign = last_and_only_stmt (then_bb);
2061 gimple *else_assign = last_and_only_stmt (else_bb);
2062 vec<data_reference_p> then_datarefs, else_datarefs;
2063 vec<ddr_p> then_ddrs, else_ddrs;
2064 gimple *then_store, *else_store;
2065 bool found, ok = false, res;
2066 struct data_dependence_relation *ddr;
2067 data_reference_p then_dr, else_dr;
2068 int i, j;
2069 tree then_lhs, else_lhs;
2070 basic_block blocks[3];
2071
2072 if (MAX_STORES_TO_SINK == 0)
2073 return false;
2074
2075 /* Handle the case with single statement in THEN_BB and ELSE_BB. */
2076 if (then_assign && else_assign)
2077 return cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb,
2078 then_assign, else_assign);
2079
2080 /* Find data references. */
2081 then_datarefs.create (1);
2082 else_datarefs.create (1);
2083 if ((find_data_references_in_bb (NULL, then_bb, &then_datarefs)
2084 == chrec_dont_know)
2085 || !then_datarefs.length ()
2086 || (find_data_references_in_bb (NULL, else_bb, &else_datarefs)
2087 == chrec_dont_know)
2088 || !else_datarefs.length ())
2089 {
2090 free_data_refs (then_datarefs);
2091 free_data_refs (else_datarefs);
2092 return false;
2093 }
2094
2095 /* Find pairs of stores with equal LHS. */
2096 auto_vec<gimple *, 1> then_stores, else_stores;
2097 FOR_EACH_VEC_ELT (then_datarefs, i, then_dr)
2098 {
2099 if (DR_IS_READ (then_dr))
2100 continue;
2101
2102 then_store = DR_STMT (then_dr);
2103 then_lhs = gimple_get_lhs (then_store);
2104 if (then_lhs == NULL_TREE)
2105 continue;
2106 found = false;
2107
2108 FOR_EACH_VEC_ELT (else_datarefs, j, else_dr)
2109 {
2110 if (DR_IS_READ (else_dr))
2111 continue;
2112
2113 else_store = DR_STMT (else_dr);
2114 else_lhs = gimple_get_lhs (else_store);
2115 if (else_lhs == NULL_TREE)
2116 continue;
2117
2118 if (operand_equal_p (then_lhs, else_lhs, 0))
2119 {
2120 found = true;
2121 break;
2122 }
2123 }
2124
2125 if (!found)
2126 continue;
2127
2128 then_stores.safe_push (then_store);
2129 else_stores.safe_push (else_store);
2130 }
2131
2132 /* No pairs of stores found. */
2133 if (!then_stores.length ()
2134 || then_stores.length () > (unsigned) MAX_STORES_TO_SINK)
2135 {
2136 free_data_refs (then_datarefs);
2137 free_data_refs (else_datarefs);
2138 return false;
2139 }
2140
2141 /* Compute and check data dependencies in both basic blocks. */
2142 then_ddrs.create (1);
2143 else_ddrs.create (1);
2144 if (!compute_all_dependences (then_datarefs, &then_ddrs,
2145 vNULL, false)
2146 || !compute_all_dependences (else_datarefs, &else_ddrs,
2147 vNULL, false))
2148 {
2149 free_dependence_relations (then_ddrs);
2150 free_dependence_relations (else_ddrs);
2151 free_data_refs (then_datarefs);
2152 free_data_refs (else_datarefs);
2153 return false;
2154 }
2155 blocks[0] = then_bb;
2156 blocks[1] = else_bb;
2157 blocks[2] = join_bb;
2158 renumber_gimple_stmt_uids_in_blocks (blocks, 3);
2159
2160 /* Check that there are no read-after-write or write-after-write dependencies
2161 in THEN_BB. */
2162 FOR_EACH_VEC_ELT (then_ddrs, i, ddr)
2163 {
2164 struct data_reference *dra = DDR_A (ddr);
2165 struct data_reference *drb = DDR_B (ddr);
2166
2167 if (DDR_ARE_DEPENDENT (ddr) != chrec_known
2168 && ((DR_IS_READ (dra) && DR_IS_WRITE (drb)
2169 && gimple_uid (DR_STMT (dra)) > gimple_uid (DR_STMT (drb)))
2170 || (DR_IS_READ (drb) && DR_IS_WRITE (dra)
2171 && gimple_uid (DR_STMT (drb)) > gimple_uid (DR_STMT (dra)))
2172 || (DR_IS_WRITE (dra) && DR_IS_WRITE (drb))))
2173 {
2174 free_dependence_relations (then_ddrs);
2175 free_dependence_relations (else_ddrs);
2176 free_data_refs (then_datarefs);
2177 free_data_refs (else_datarefs);
2178 return false;
2179 }
2180 }
2181
2182 /* Check that there are no read-after-write or write-after-write dependencies
2183 in ELSE_BB. */
2184 FOR_EACH_VEC_ELT (else_ddrs, i, ddr)
2185 {
2186 struct data_reference *dra = DDR_A (ddr);
2187 struct data_reference *drb = DDR_B (ddr);
2188
2189 if (DDR_ARE_DEPENDENT (ddr) != chrec_known
2190 && ((DR_IS_READ (dra) && DR_IS_WRITE (drb)
2191 && gimple_uid (DR_STMT (dra)) > gimple_uid (DR_STMT (drb)))
2192 || (DR_IS_READ (drb) && DR_IS_WRITE (dra)
2193 && gimple_uid (DR_STMT (drb)) > gimple_uid (DR_STMT (dra)))
2194 || (DR_IS_WRITE (dra) && DR_IS_WRITE (drb))))
2195 {
2196 free_dependence_relations (then_ddrs);
2197 free_dependence_relations (else_ddrs);
2198 free_data_refs (then_datarefs);
2199 free_data_refs (else_datarefs);
2200 return false;
2201 }
2202 }
2203
2204 /* Sink stores with same LHS. */
2205 FOR_EACH_VEC_ELT (then_stores, i, then_store)
2206 {
2207 else_store = else_stores[i];
2208 res = cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb,
2209 then_store, else_store);
2210 ok = ok || res;
2211 }
2212
2213 free_dependence_relations (then_ddrs);
2214 free_dependence_relations (else_ddrs);
2215 free_data_refs (then_datarefs);
2216 free_data_refs (else_datarefs);
2217
2218 return ok;
2219}
2220
2221/* Return TRUE if STMT has a VUSE whose corresponding VDEF is in BB. */
2222
2223static bool
2224local_mem_dependence (gimple *stmt, basic_block bb)
2225{
2226 tree vuse = gimple_vuse (stmt);
2227 gimple *def;
2228
2229 if (!vuse)
2230 return false;
2231
2232 def = SSA_NAME_DEF_STMT (vuse);
2233 return (def && gimple_bb (def) == bb);
2234}
2235
2236/* Given a "diamond" control-flow pattern where BB0 tests a condition,
2237 BB1 and BB2 are "then" and "else" blocks dependent on this test,
2238 and BB3 rejoins control flow following BB1 and BB2, look for
2239 opportunities to hoist loads as follows. If BB3 contains a PHI of
2240 two loads, one each occurring in BB1 and BB2, and the loads are
2241 provably of adjacent fields in the same structure, then move both
2242 loads into BB0. Of course this can only be done if there are no
2243 dependencies preventing such motion.
2244
2245 One of the hoisted loads will always be speculative, so the
2246 transformation is currently conservative:
2247
2248 - The fields must be strictly adjacent.
2249 - The two fields must occupy a single memory block that is
2250 guaranteed to not cross a page boundary.
2251
2252 The last is difficult to prove, as such memory blocks should be
2253 aligned on the minimum of the stack alignment boundary and the
2254 alignment guaranteed by heap allocation interfaces. Thus we rely
2255 on a parameter for the alignment value.
2256
2257 Provided a good value is used for the last case, the first
2258 restriction could possibly be relaxed. */
2259
2260static void
2261hoist_adjacent_loads (basic_block bb0, basic_block bb1,
2262 basic_block bb2, basic_block bb3)
2263{
2264 int param_align = PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE);
2265 unsigned param_align_bits = (unsigned) (param_align * BITS_PER_UNIT);
2266 gphi_iterator gsi;
2267
2268 /* Walk the phis in bb3 looking for an opportunity. We are looking
2269 for phis of two SSA names, one each of which is defined in bb1 and
2270 bb2. */
2271 for (gsi = gsi_start_phis (bb3); !gsi_end_p (gsi); gsi_next (&gsi))
2272 {
2273 gphi *phi_stmt = gsi.phi ();
2274 gimple *def1, *def2;
2275 tree arg1, arg2, ref1, ref2, field1, field2;
2276 tree tree_offset1, tree_offset2, tree_size2, next;
2277 int offset1, offset2, size2;
2278 unsigned align1;
2279 gimple_stmt_iterator gsi2;
2280 basic_block bb_for_def1, bb_for_def2;
2281
2282 if (gimple_phi_num_args (phi_stmt) != 2
2283 || virtual_operand_p (gimple_phi_result (phi_stmt)))
2284 continue;
2285
2286 arg1 = gimple_phi_arg_def (phi_stmt, 0);
2287 arg2 = gimple_phi_arg_def (phi_stmt, 1);
2288
2289 if (TREE_CODE (arg1) != SSA_NAME
2290 || TREE_CODE (arg2) != SSA_NAME
2291 || SSA_NAME_IS_DEFAULT_DEF (arg1)
2292 || SSA_NAME_IS_DEFAULT_DEF (arg2))
2293 continue;
2294
2295 def1 = SSA_NAME_DEF_STMT (arg1);
2296 def2 = SSA_NAME_DEF_STMT (arg2);
2297
2298 if ((gimple_bb (def1) != bb1 || gimple_bb (def2) != bb2)
2299 && (gimple_bb (def2) != bb1 || gimple_bb (def1) != bb2))
2300 continue;
2301
2302 /* Check the mode of the arguments to be sure a conditional move
2303 can be generated for it. */
2304 if (optab_handler (movcc_optab, TYPE_MODE (TREE_TYPE (arg1)))
2305 == CODE_FOR_nothing)
2306 continue;
2307
2308 /* Both statements must be assignments whose RHS is a COMPONENT_REF. */
2309 if (!gimple_assign_single_p (def1)
2310 || !gimple_assign_single_p (def2)
2311 || gimple_has_volatile_ops (def1)
2312 || gimple_has_volatile_ops (def2))
2313 continue;
2314
2315 ref1 = gimple_assign_rhs1 (def1);
2316 ref2 = gimple_assign_rhs1 (def2);
2317
2318 if (TREE_CODE (ref1) != COMPONENT_REF
2319 || TREE_CODE (ref2) != COMPONENT_REF)
2320 continue;
2321
2322 /* The zeroth operand of the two component references must be
2323 identical. It is not sufficient to compare get_base_address of
2324 the two references, because this could allow for different
2325 elements of the same array in the two trees. It is not safe to
2326 assume that the existence of one array element implies the
2327 existence of a different one. */
2328 if (!operand_equal_p (TREE_OPERAND (ref1, 0), TREE_OPERAND (ref2, 0), 0))
2329 continue;
2330
2331 field1 = TREE_OPERAND (ref1, 1);
2332 field2 = TREE_OPERAND (ref2, 1);
2333
2334 /* Check for field adjacency, and ensure field1 comes first. */
2335 for (next = DECL_CHAIN (field1);
2336 next && TREE_CODE (next) != FIELD_DECL;
2337 next = DECL_CHAIN (next))
2338 ;
2339
2340 if (next != field2)
2341 {
2342 for (next = DECL_CHAIN (field2);
2343 next && TREE_CODE (next) != FIELD_DECL;
2344 next = DECL_CHAIN (next))
2345 ;
2346
2347 if (next != field1)
2348 continue;
2349
2350 std::swap (field1, field2);
2351 std::swap (def1, def2);
2352 }
2353
2354 bb_for_def1 = gimple_bb (def1);
2355 bb_for_def2 = gimple_bb (def2);
2356
2357 /* Check for proper alignment of the first field. */
2358 tree_offset1 = bit_position (field1);
2359 tree_offset2 = bit_position (field2);
2360 tree_size2 = DECL_SIZE (field2);
2361
2362 if (!tree_fits_uhwi_p (tree_offset1)
2363 || !tree_fits_uhwi_p (tree_offset2)
2364 || !tree_fits_uhwi_p (tree_size2))
2365 continue;
2366
2367 offset1 = tree_to_uhwi (tree_offset1);
2368 offset2 = tree_to_uhwi (tree_offset2);
2369 size2 = tree_to_uhwi (tree_size2);
2370 align1 = DECL_ALIGN (field1) % param_align_bits;
2371
2372 if (offset1 % BITS_PER_UNIT != 0)
2373 continue;
2374
2375 /* For profitability, the two field references should fit within
2376 a single cache line. */
2377 if (align1 + offset2 - offset1 + size2 > param_align_bits)
2378 continue;
2379
2380 /* The two expressions cannot be dependent upon vdefs defined
2381 in bb1/bb2. */
2382 if (local_mem_dependence (def1, bb_for_def1)
2383 || local_mem_dependence (def2, bb_for_def2))
2384 continue;
2385
2386 /* The conditions are satisfied; hoist the loads from bb1 and bb2 into
2387 bb0. We hoist the first one first so that a cache miss is handled
2388 efficiently regardless of hardware cache-fill policy. */
2389 gsi2 = gsi_for_stmt (def1);
2390 gsi_move_to_bb_end (&gsi2, bb0);
2391 gsi2 = gsi_for_stmt (def2);
2392 gsi_move_to_bb_end (&gsi2, bb0);
2393
2394 if (dump_file && (dump_flags & TDF_DETAILS))
2395 {
2396 fprintf (dump_file,
2397 "\nHoisting adjacent loads from %d and %d into %d: \n",
2398 bb_for_def1->index, bb_for_def2->index, bb0->index);
2399 print_gimple_stmt (dump_file, def1, 0, TDF_VOPS|TDF_MEMSYMS);
2400 print_gimple_stmt (dump_file, def2, 0, TDF_VOPS|TDF_MEMSYMS);
2401 }
2402 }
2403}
2404
2405/* Determine whether we should attempt to hoist adjacent loads out of
2406 diamond patterns in pass_phiopt. Always hoist loads if
2407 -fhoist-adjacent-loads is specified and the target machine has
2408 both a conditional move instruction and a defined cache line size. */
2409
2410static bool
2411gate_hoist_loads (void)
2412{
2413 return (flag_hoist_adjacent_loads == 1
2414 && PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE)
2415 && HAVE_conditional_move);
2416}
2417
2418/* This pass tries to replaces an if-then-else block with an
2419 assignment. We have four kinds of transformations. Some of these
2420 transformations are also performed by the ifcvt RTL optimizer.
2421
2422 Conditional Replacement
2423 -----------------------
2424
2425 This transformation, implemented in conditional_replacement,
2426 replaces
2427
2428 bb0:
2429 if (cond) goto bb2; else goto bb1;
2430 bb1:
2431 bb2:
2432 x = PHI <0 (bb1), 1 (bb0), ...>;
2433
2434 with
2435
2436 bb0:
2437 x' = cond;
2438 goto bb2;
2439 bb2:
2440 x = PHI <x' (bb0), ...>;
2441
2442 We remove bb1 as it becomes unreachable. This occurs often due to
2443 gimplification of conditionals.
2444
2445 Value Replacement
2446 -----------------
2447
2448 This transformation, implemented in value_replacement, replaces
2449
2450 bb0:
2451 if (a != b) goto bb2; else goto bb1;
2452 bb1:
2453 bb2:
2454 x = PHI <a (bb1), b (bb0), ...>;
2455
2456 with
2457
2458 bb0:
2459 bb2:
2460 x = PHI <b (bb0), ...>;
2461
2462 This opportunity can sometimes occur as a result of other
2463 optimizations.
2464
2465
2466 Another case caught by value replacement looks like this:
2467
2468 bb0:
2469 t1 = a == CONST;
2470 t2 = b > c;
2471 t3 = t1 & t2;
2472 if (t3 != 0) goto bb1; else goto bb2;
2473 bb1:
2474 bb2:
2475 x = PHI (CONST, a)
2476
2477 Gets replaced with:
2478 bb0:
2479 bb2:
2480 t1 = a == CONST;
2481 t2 = b > c;
2482 t3 = t1 & t2;
2483 x = a;
2484
2485 ABS Replacement
2486 ---------------
2487
2488 This transformation, implemented in abs_replacement, replaces
2489
2490 bb0:
2491 if (a >= 0) goto bb2; else goto bb1;
2492 bb1:
2493 x = -a;
2494 bb2:
2495 x = PHI <x (bb1), a (bb0), ...>;
2496
2497 with
2498
2499 bb0:
2500 x' = ABS_EXPR< a >;
2501 bb2:
2502 x = PHI <x' (bb0), ...>;
2503
2504 MIN/MAX Replacement
2505 -------------------
2506
2507 This transformation, minmax_replacement replaces
2508
2509 bb0:
2510 if (a <= b) goto bb2; else goto bb1;
2511 bb1:
2512 bb2:
2513 x = PHI <b (bb1), a (bb0), ...>;
2514
2515 with
2516
2517 bb0:
2518 x' = MIN_EXPR (a, b)
2519 bb2:
2520 x = PHI <x' (bb0), ...>;
2521
2522 A similar transformation is done for MAX_EXPR.
2523
2524
2525 This pass also performs a fifth transformation of a slightly different
2526 flavor.
2527
2528 Factor conversion in COND_EXPR
2529 ------------------------------
2530
2531 This transformation factors the conversion out of COND_EXPR with
2532 factor_out_conditional_conversion.
2533
2534 For example:
2535 if (a <= CST) goto <bb 3>; else goto <bb 4>;
2536 <bb 3>:
2537 tmp = (int) a;
2538 <bb 4>:
2539 tmp = PHI <tmp, CST>
2540
2541 Into:
2542 if (a <= CST) goto <bb 3>; else goto <bb 4>;
2543 <bb 3>:
2544 <bb 4>:
2545 a = PHI <a, CST>
2546 tmp = (int) a;
2547
2548 Adjacent Load Hoisting
2549 ----------------------
2550
2551 This transformation replaces
2552
2553 bb0:
2554 if (...) goto bb2; else goto bb1;
2555 bb1:
2556 x1 = (<expr>).field1;
2557 goto bb3;
2558 bb2:
2559 x2 = (<expr>).field2;
2560 bb3:
2561 # x = PHI <x1, x2>;
2562
2563 with
2564
2565 bb0:
2566 x1 = (<expr>).field1;
2567 x2 = (<expr>).field2;
2568 if (...) goto bb2; else goto bb1;
2569 bb1:
2570 goto bb3;
2571 bb2:
2572 bb3:
2573 # x = PHI <x1, x2>;
2574
2575 The purpose of this transformation is to enable generation of conditional
2576 move instructions such as Intel CMOVE or PowerPC ISEL. Because one of
2577 the loads is speculative, the transformation is restricted to very
2578 specific cases to avoid introducing a page fault. We are looking for
2579 the common idiom:
2580
2581 if (...)
2582 x = y->left;
2583 else
2584 x = y->right;
2585
2586 where left and right are typically adjacent pointers in a tree structure. */
2587
2588namespace {
2589
2590const pass_data pass_data_phiopt =
2591{
2592 GIMPLE_PASS, /* type */
2593 "phiopt", /* name */
2594 OPTGROUP_NONE, /* optinfo_flags */
2595 TV_TREE_PHIOPT, /* tv_id */
2596 ( PROP_cfg | PROP_ssa ), /* properties_required */
2597 0, /* properties_provided */
2598 0, /* properties_destroyed */
2599 0, /* todo_flags_start */
2600 0, /* todo_flags_finish */
2601};
2602
2603class pass_phiopt : public gimple_opt_pass
2604{
2605public:
2606 pass_phiopt (gcc::context *ctxt)
2607 : gimple_opt_pass (pass_data_phiopt, ctxt)
2608 {}
2609
2610 /* opt_pass methods: */
2611 opt_pass * clone () { return new pass_phiopt (m_ctxt); }
2612 virtual bool gate (function *) { return flag_ssa_phiopt; }
2613 virtual unsigned int execute (function *)
2614 {
2615 return tree_ssa_phiopt_worker (false, gate_hoist_loads ());
2616 }
2617
2618}; // class pass_phiopt
2619
2620} // anon namespace
2621
2622gimple_opt_pass *
2623make_pass_phiopt (gcc::context *ctxt)
2624{
2625 return new pass_phiopt (ctxt);
2626}
2627
2628namespace {
2629
2630const pass_data pass_data_cselim =
2631{
2632 GIMPLE_PASS, /* type */
2633 "cselim", /* name */
2634 OPTGROUP_NONE, /* optinfo_flags */
2635 TV_TREE_PHIOPT, /* tv_id */
2636 ( PROP_cfg | PROP_ssa ), /* properties_required */
2637 0, /* properties_provided */
2638 0, /* properties_destroyed */
2639 0, /* todo_flags_start */
2640 0, /* todo_flags_finish */
2641};
2642
2643class pass_cselim : public gimple_opt_pass
2644{
2645public:
2646 pass_cselim (gcc::context *ctxt)
2647 : gimple_opt_pass (pass_data_cselim, ctxt)
2648 {}
2649
2650 /* opt_pass methods: */
2651 virtual bool gate (function *) { return flag_tree_cselim; }
2652 virtual unsigned int execute (function *) { return tree_ssa_cs_elim (); }
2653
2654}; // class pass_cselim
2655
2656} // anon namespace
2657
2658gimple_opt_pass *
2659make_pass_cselim (gcc::context *ctxt)
2660{
2661 return new pass_cselim (ctxt);
2662}
2663