tree-ssa.c (verify_ssa): With -O0 we do not need VOPs.
[gcc.git] / gcc / tree-ssa.c
1 /* Miscellaneous SSA utility functions.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009
3 Free Software Foundation, Inc.
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
10 any later version.
11
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with 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 "tm.h"
25 #include "tree.h"
26 #include "flags.h"
27 #include "rtl.h"
28 #include "tm_p.h"
29 #include "ggc.h"
30 #include "langhooks.h"
31 #include "hard-reg-set.h"
32 #include "basic-block.h"
33 #include "output.h"
34 #include "expr.h"
35 #include "function.h"
36 #include "diagnostic.h"
37 #include "bitmap.h"
38 #include "pointer-set.h"
39 #include "tree-flow.h"
40 #include "gimple.h"
41 #include "tree-inline.h"
42 #include "varray.h"
43 #include "timevar.h"
44 #include "hashtab.h"
45 #include "tree-dump.h"
46 #include "tree-pass.h"
47 #include "toplev.h"
48
49 /* Pointer map of variable mappings, keyed by edge. */
50 static struct pointer_map_t *edge_var_maps;
51
52
53 /* Add a mapping with PHI RESULT and PHI DEF associated with edge E. */
54
55 void
56 redirect_edge_var_map_add (edge e, tree result, tree def)
57 {
58 void **slot;
59 edge_var_map_vector old_head, head;
60 edge_var_map new_node;
61
62 if (edge_var_maps == NULL)
63 edge_var_maps = pointer_map_create ();
64
65 slot = pointer_map_insert (edge_var_maps, e);
66 old_head = head = (edge_var_map_vector) *slot;
67 if (!head)
68 {
69 head = VEC_alloc (edge_var_map, heap, 5);
70 *slot = head;
71 }
72 new_node.def = def;
73 new_node.result = result;
74
75 VEC_safe_push (edge_var_map, heap, head, &new_node);
76 if (old_head != head)
77 {
78 /* The push did some reallocation. Update the pointer map. */
79 *slot = head;
80 }
81 }
82
83
84 /* Clear the var mappings in edge E. */
85
86 void
87 redirect_edge_var_map_clear (edge e)
88 {
89 void **slot;
90 edge_var_map_vector head;
91
92 if (!edge_var_maps)
93 return;
94
95 slot = pointer_map_contains (edge_var_maps, e);
96
97 if (slot)
98 {
99 head = (edge_var_map_vector) *slot;
100 VEC_free (edge_var_map, heap, head);
101 *slot = NULL;
102 }
103 }
104
105
106 /* Duplicate the redirected var mappings in OLDE in NEWE.
107
108 Since we can't remove a mapping, let's just duplicate it. This assumes a
109 pointer_map can have multiple edges mapping to the same var_map (many to
110 one mapping), since we don't remove the previous mappings. */
111
112 void
113 redirect_edge_var_map_dup (edge newe, edge olde)
114 {
115 void **new_slot, **old_slot;
116 edge_var_map_vector head;
117
118 if (!edge_var_maps)
119 return;
120
121 new_slot = pointer_map_insert (edge_var_maps, newe);
122 old_slot = pointer_map_contains (edge_var_maps, olde);
123 if (!old_slot)
124 return;
125 head = (edge_var_map_vector) *old_slot;
126
127 if (head)
128 *new_slot = VEC_copy (edge_var_map, heap, head);
129 else
130 *new_slot = VEC_alloc (edge_var_map, heap, 5);
131 }
132
133
134 /* Return the variable mappings for a given edge. If there is none, return
135 NULL. */
136
137 edge_var_map_vector
138 redirect_edge_var_map_vector (edge e)
139 {
140 void **slot;
141
142 /* Hey, what kind of idiot would... you'd be surprised. */
143 if (!edge_var_maps)
144 return NULL;
145
146 slot = pointer_map_contains (edge_var_maps, e);
147 if (!slot)
148 return NULL;
149
150 return (edge_var_map_vector) *slot;
151 }
152
153 /* Used by redirect_edge_var_map_destroy to free all memory. */
154
155 static bool
156 free_var_map_entry (const void *key ATTRIBUTE_UNUSED,
157 void **value,
158 void *data ATTRIBUTE_UNUSED)
159 {
160 edge_var_map_vector head = (edge_var_map_vector) *value;
161 VEC_free (edge_var_map, heap, head);
162 return true;
163 }
164
165 /* Clear the edge variable mappings. */
166
167 void
168 redirect_edge_var_map_destroy (void)
169 {
170 if (edge_var_maps)
171 {
172 pointer_map_traverse (edge_var_maps, free_var_map_entry, NULL);
173 pointer_map_destroy (edge_var_maps);
174 edge_var_maps = NULL;
175 }
176 }
177
178
179 /* Remove the corresponding arguments from the PHI nodes in E's
180 destination block and redirect it to DEST. Return redirected edge.
181 The list of removed arguments is stored in a vector accessed
182 through edge_var_maps. */
183
184 edge
185 ssa_redirect_edge (edge e, basic_block dest)
186 {
187 gimple_stmt_iterator gsi;
188 gimple phi;
189
190 redirect_edge_var_map_clear (e);
191
192 /* Remove the appropriate PHI arguments in E's destination block. */
193 for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); gsi_next (&gsi))
194 {
195 tree def;
196
197 phi = gsi_stmt (gsi);
198 def = gimple_phi_arg_def (phi, e->dest_idx);
199
200 if (def == NULL_TREE)
201 continue;
202
203 redirect_edge_var_map_add (e, gimple_phi_result (phi), def);
204 }
205
206 e = redirect_edge_succ_nodup (e, dest);
207
208 return e;
209 }
210
211
212 /* Add PHI arguments queued in PENDING_STMT list on edge E to edge
213 E->dest. */
214
215 void
216 flush_pending_stmts (edge e)
217 {
218 gimple phi;
219 edge_var_map_vector v;
220 edge_var_map *vm;
221 int i;
222 gimple_stmt_iterator gsi;
223
224 v = redirect_edge_var_map_vector (e);
225 if (!v)
226 return;
227
228 for (gsi = gsi_start_phis (e->dest), i = 0;
229 !gsi_end_p (gsi) && VEC_iterate (edge_var_map, v, i, vm);
230 gsi_next (&gsi), i++)
231 {
232 tree def;
233
234 phi = gsi_stmt (gsi);
235 def = redirect_edge_var_map_def (vm);
236 add_phi_arg (phi, def, e);
237 }
238
239 redirect_edge_var_map_clear (e);
240 }
241
242 /* Return true if SSA_NAME is malformed and mark it visited.
243
244 IS_VIRTUAL is true if this SSA_NAME was found inside a virtual
245 operand. */
246
247 static bool
248 verify_ssa_name (tree ssa_name, bool is_virtual)
249 {
250 if (TREE_CODE (ssa_name) != SSA_NAME)
251 {
252 error ("expected an SSA_NAME object");
253 return true;
254 }
255
256 if (TREE_TYPE (ssa_name) != TREE_TYPE (SSA_NAME_VAR (ssa_name)))
257 {
258 error ("type mismatch between an SSA_NAME and its symbol");
259 return true;
260 }
261
262 if (SSA_NAME_IN_FREE_LIST (ssa_name))
263 {
264 error ("found an SSA_NAME that had been released into the free pool");
265 return true;
266 }
267
268 if (is_virtual && is_gimple_reg (ssa_name))
269 {
270 error ("found a virtual definition for a GIMPLE register");
271 return true;
272 }
273
274 if (is_virtual && SSA_NAME_VAR (ssa_name) != gimple_vop (cfun))
275 {
276 error ("virtual SSA name for non-VOP decl");
277 return true;
278 }
279
280 if (!is_virtual && !is_gimple_reg (ssa_name))
281 {
282 error ("found a real definition for a non-register");
283 return true;
284 }
285
286 if (SSA_NAME_IS_DEFAULT_DEF (ssa_name)
287 && !gimple_nop_p (SSA_NAME_DEF_STMT (ssa_name)))
288 {
289 error ("found a default name with a non-empty defining statement");
290 return true;
291 }
292
293 return false;
294 }
295
296
297 /* Return true if the definition of SSA_NAME at block BB is malformed.
298
299 STMT is the statement where SSA_NAME is created.
300
301 DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME
302 version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set,
303 it means that the block in that array slot contains the
304 definition of SSA_NAME.
305
306 IS_VIRTUAL is true if SSA_NAME is created by a VDEF. */
307
308 static bool
309 verify_def (basic_block bb, basic_block *definition_block, tree ssa_name,
310 gimple stmt, bool is_virtual)
311 {
312 if (verify_ssa_name (ssa_name, is_virtual))
313 goto err;
314
315 if (definition_block[SSA_NAME_VERSION (ssa_name)])
316 {
317 error ("SSA_NAME created in two different blocks %i and %i",
318 definition_block[SSA_NAME_VERSION (ssa_name)]->index, bb->index);
319 goto err;
320 }
321
322 definition_block[SSA_NAME_VERSION (ssa_name)] = bb;
323
324 if (SSA_NAME_DEF_STMT (ssa_name) != stmt)
325 {
326 error ("SSA_NAME_DEF_STMT is wrong");
327 fprintf (stderr, "Expected definition statement:\n");
328 print_gimple_stmt (stderr, SSA_NAME_DEF_STMT (ssa_name), 4, TDF_VOPS);
329 fprintf (stderr, "\nActual definition statement:\n");
330 print_gimple_stmt (stderr, stmt, 4, TDF_VOPS);
331 goto err;
332 }
333
334 return false;
335
336 err:
337 fprintf (stderr, "while verifying SSA_NAME ");
338 print_generic_expr (stderr, ssa_name, 0);
339 fprintf (stderr, " in statement\n");
340 print_gimple_stmt (stderr, stmt, 4, TDF_VOPS);
341
342 return true;
343 }
344
345
346 /* Return true if the use of SSA_NAME at statement STMT in block BB is
347 malformed.
348
349 DEF_BB is the block where SSA_NAME was found to be created.
350
351 IDOM contains immediate dominator information for the flowgraph.
352
353 CHECK_ABNORMAL is true if the caller wants to check whether this use
354 is flowing through an abnormal edge (only used when checking PHI
355 arguments).
356
357 If NAMES_DEFINED_IN_BB is not NULL, it contains a bitmap of ssa names
358 that are defined before STMT in basic block BB. */
359
360 static bool
361 verify_use (basic_block bb, basic_block def_bb, use_operand_p use_p,
362 gimple stmt, bool check_abnormal, bitmap names_defined_in_bb)
363 {
364 bool err = false;
365 tree ssa_name = USE_FROM_PTR (use_p);
366
367 if (!TREE_VISITED (ssa_name))
368 if (verify_imm_links (stderr, ssa_name))
369 err = true;
370
371 TREE_VISITED (ssa_name) = 1;
372
373 if (gimple_nop_p (SSA_NAME_DEF_STMT (ssa_name))
374 && SSA_NAME_IS_DEFAULT_DEF (ssa_name))
375 ; /* Default definitions have empty statements. Nothing to do. */
376 else if (!def_bb)
377 {
378 error ("missing definition");
379 err = true;
380 }
381 else if (bb != def_bb
382 && !dominated_by_p (CDI_DOMINATORS, bb, def_bb))
383 {
384 error ("definition in block %i does not dominate use in block %i",
385 def_bb->index, bb->index);
386 err = true;
387 }
388 else if (bb == def_bb
389 && names_defined_in_bb != NULL
390 && !bitmap_bit_p (names_defined_in_bb, SSA_NAME_VERSION (ssa_name)))
391 {
392 error ("definition in block %i follows the use", def_bb->index);
393 err = true;
394 }
395
396 if (check_abnormal
397 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (ssa_name))
398 {
399 error ("SSA_NAME_OCCURS_IN_ABNORMAL_PHI should be set");
400 err = true;
401 }
402
403 /* Make sure the use is in an appropriate list by checking the previous
404 element to make sure it's the same. */
405 if (use_p->prev == NULL)
406 {
407 error ("no immediate_use list");
408 err = true;
409 }
410 else
411 {
412 tree listvar;
413 if (use_p->prev->use == NULL)
414 listvar = use_p->prev->loc.ssa_name;
415 else
416 listvar = USE_FROM_PTR (use_p->prev);
417 if (listvar != ssa_name)
418 {
419 error ("wrong immediate use list");
420 err = true;
421 }
422 }
423
424 if (err)
425 {
426 fprintf (stderr, "for SSA_NAME: ");
427 print_generic_expr (stderr, ssa_name, TDF_VOPS);
428 fprintf (stderr, " in statement:\n");
429 print_gimple_stmt (stderr, stmt, 0, TDF_VOPS);
430 }
431
432 return err;
433 }
434
435
436 /* Return true if any of the arguments for PHI node PHI at block BB is
437 malformed.
438
439 DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME
440 version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set,
441 it means that the block in that array slot contains the
442 definition of SSA_NAME. */
443
444 static bool
445 verify_phi_args (gimple phi, basic_block bb, basic_block *definition_block)
446 {
447 edge e;
448 bool err = false;
449 size_t i, phi_num_args = gimple_phi_num_args (phi);
450
451 if (EDGE_COUNT (bb->preds) != phi_num_args)
452 {
453 error ("incoming edge count does not match number of PHI arguments");
454 err = true;
455 goto error;
456 }
457
458 for (i = 0; i < phi_num_args; i++)
459 {
460 use_operand_p op_p = gimple_phi_arg_imm_use_ptr (phi, i);
461 tree op = USE_FROM_PTR (op_p);
462
463 e = EDGE_PRED (bb, i);
464
465 if (op == NULL_TREE)
466 {
467 error ("PHI argument is missing for edge %d->%d",
468 e->src->index,
469 e->dest->index);
470 err = true;
471 goto error;
472 }
473
474 if (TREE_CODE (op) != SSA_NAME && !is_gimple_min_invariant (op))
475 {
476 error ("PHI argument is not SSA_NAME, or invariant");
477 err = true;
478 }
479
480 if (TREE_CODE (op) == SSA_NAME)
481 {
482 err = verify_ssa_name (op, !is_gimple_reg (gimple_phi_result (phi)));
483 err |= verify_use (e->src, definition_block[SSA_NAME_VERSION (op)],
484 op_p, phi, e->flags & EDGE_ABNORMAL, NULL);
485 }
486
487 if (TREE_CODE (op) == ADDR_EXPR)
488 {
489 tree base = TREE_OPERAND (op, 0);
490 while (handled_component_p (base))
491 base = TREE_OPERAND (base, 0);
492 if ((TREE_CODE (base) == VAR_DECL
493 || TREE_CODE (base) == PARM_DECL
494 || TREE_CODE (base) == RESULT_DECL)
495 && !TREE_ADDRESSABLE (base))
496 {
497 error ("address taken, but ADDRESSABLE bit not set");
498 err = true;
499 }
500 }
501
502 if (e->dest != bb)
503 {
504 error ("wrong edge %d->%d for PHI argument",
505 e->src->index, e->dest->index);
506 err = true;
507 }
508
509 if (err)
510 {
511 fprintf (stderr, "PHI argument\n");
512 print_generic_stmt (stderr, op, TDF_VOPS);
513 goto error;
514 }
515 }
516
517 error:
518 if (err)
519 {
520 fprintf (stderr, "for PHI node\n");
521 print_gimple_stmt (stderr, phi, 0, TDF_VOPS|TDF_MEMSYMS);
522 }
523
524
525 return err;
526 }
527
528
529 /* Verify common invariants in the SSA web.
530 TODO: verify the variable annotations. */
531
532 void
533 verify_ssa (bool check_modified_stmt)
534 {
535 size_t i;
536 basic_block bb;
537 basic_block *definition_block = XCNEWVEC (basic_block, num_ssa_names);
538 ssa_op_iter iter;
539 tree op;
540 enum dom_state orig_dom_state = dom_info_state (CDI_DOMINATORS);
541 bitmap names_defined_in_bb = BITMAP_ALLOC (NULL);
542
543 gcc_assert (!need_ssa_update_p (cfun));
544
545 verify_stmts ();
546
547 timevar_push (TV_TREE_SSA_VERIFY);
548
549 /* Keep track of SSA names present in the IL. */
550 for (i = 1; i < num_ssa_names; i++)
551 {
552 tree name = ssa_name (i);
553 if (name)
554 {
555 gimple stmt;
556 TREE_VISITED (name) = 0;
557
558 stmt = SSA_NAME_DEF_STMT (name);
559 if (!gimple_nop_p (stmt))
560 {
561 basic_block bb = gimple_bb (stmt);
562 verify_def (bb, definition_block,
563 name, stmt, !is_gimple_reg (name));
564
565 }
566 }
567 }
568
569 calculate_dominance_info (CDI_DOMINATORS);
570
571 /* Now verify all the uses and make sure they agree with the definitions
572 found in the previous pass. */
573 FOR_EACH_BB (bb)
574 {
575 edge e;
576 gimple phi;
577 edge_iterator ei;
578 gimple_stmt_iterator gsi;
579
580 /* Make sure that all edges have a clear 'aux' field. */
581 FOR_EACH_EDGE (e, ei, bb->preds)
582 {
583 if (e->aux)
584 {
585 error ("AUX pointer initialized for edge %d->%d", e->src->index,
586 e->dest->index);
587 goto err;
588 }
589 }
590
591 /* Verify the arguments for every PHI node in the block. */
592 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
593 {
594 phi = gsi_stmt (gsi);
595 if (verify_phi_args (phi, bb, definition_block))
596 goto err;
597
598 bitmap_set_bit (names_defined_in_bb,
599 SSA_NAME_VERSION (gimple_phi_result (phi)));
600 }
601
602 /* Now verify all the uses and vuses in every statement of the block. */
603 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
604 {
605 gimple stmt = gsi_stmt (gsi);
606 use_operand_p use_p;
607 bool has_err;
608
609 if (check_modified_stmt && gimple_modified_p (stmt))
610 {
611 error ("stmt (%p) marked modified after optimization pass: ",
612 (void *)stmt);
613 print_gimple_stmt (stderr, stmt, 0, TDF_VOPS);
614 goto err;
615 }
616
617 if (is_gimple_assign (stmt)
618 && TREE_CODE (gimple_assign_lhs (stmt)) != SSA_NAME)
619 {
620 tree lhs, base_address;
621
622 lhs = gimple_assign_lhs (stmt);
623 base_address = get_base_address (lhs);
624
625 if (base_address
626 && SSA_VAR_P (base_address)
627 && !gimple_vdef (stmt)
628 && optimize > 0)
629 {
630 error ("statement makes a memory store, but has no VDEFS");
631 print_gimple_stmt (stderr, stmt, 0, TDF_VOPS);
632 goto err;
633 }
634 }
635
636 /* Verify the single virtual operand and its constraints. */
637 has_err = false;
638 if (gimple_vdef (stmt))
639 {
640 if (gimple_vdef_op (stmt) == NULL_DEF_OPERAND_P)
641 {
642 error ("statement has VDEF operand not in defs list");
643 has_err = true;
644 }
645 if (!gimple_vuse (stmt))
646 {
647 error ("statement has VDEF but no VUSE operand");
648 has_err = true;
649 }
650 else if (SSA_NAME_VAR (gimple_vdef (stmt))
651 != SSA_NAME_VAR (gimple_vuse (stmt)))
652 {
653 error ("VDEF and VUSE do not use the same symbol");
654 has_err = true;
655 }
656 has_err |= verify_ssa_name (gimple_vdef (stmt), true);
657 }
658 if (gimple_vuse (stmt))
659 {
660 if (gimple_vuse_op (stmt) == NULL_USE_OPERAND_P)
661 {
662 error ("statement has VUSE operand not in uses list");
663 has_err = true;
664 }
665 has_err |= verify_ssa_name (gimple_vuse (stmt), true);
666 }
667 if (has_err)
668 {
669 error ("in statement");
670 print_gimple_stmt (stderr, stmt, 0, TDF_VOPS|TDF_MEMSYMS);
671 goto err;
672 }
673
674 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE|SSA_OP_DEF)
675 {
676 if (verify_ssa_name (op, false))
677 {
678 error ("in statement");
679 print_gimple_stmt (stderr, stmt, 0, TDF_VOPS|TDF_MEMSYMS);
680 goto err;
681 }
682 }
683
684 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE|SSA_OP_VUSE)
685 {
686 op = USE_FROM_PTR (use_p);
687 if (verify_use (bb, definition_block[SSA_NAME_VERSION (op)],
688 use_p, stmt, false, names_defined_in_bb))
689 goto err;
690 }
691
692 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_DEFS)
693 {
694 if (SSA_NAME_DEF_STMT (op) != stmt)
695 {
696 error ("SSA_NAME_DEF_STMT is wrong");
697 fprintf (stderr, "Expected definition statement:\n");
698 print_gimple_stmt (stderr, stmt, 4, TDF_VOPS);
699 fprintf (stderr, "\nActual definition statement:\n");
700 print_gimple_stmt (stderr, SSA_NAME_DEF_STMT (op),
701 4, TDF_VOPS);
702 goto err;
703 }
704 bitmap_set_bit (names_defined_in_bb, SSA_NAME_VERSION (op));
705 }
706 }
707
708 bitmap_clear (names_defined_in_bb);
709 }
710
711 free (definition_block);
712
713 /* Restore the dominance information to its prior known state, so
714 that we do not perturb the compiler's subsequent behavior. */
715 if (orig_dom_state == DOM_NONE)
716 free_dominance_info (CDI_DOMINATORS);
717 else
718 set_dom_info_availability (CDI_DOMINATORS, orig_dom_state);
719
720 BITMAP_FREE (names_defined_in_bb);
721 timevar_pop (TV_TREE_SSA_VERIFY);
722 return;
723
724 err:
725 internal_error ("verify_ssa failed");
726 }
727
728 /* Return true if the uid in both int tree maps are equal. */
729
730 int
731 int_tree_map_eq (const void *va, const void *vb)
732 {
733 const struct int_tree_map *a = (const struct int_tree_map *) va;
734 const struct int_tree_map *b = (const struct int_tree_map *) vb;
735 return (a->uid == b->uid);
736 }
737
738 /* Hash a UID in a int_tree_map. */
739
740 unsigned int
741 int_tree_map_hash (const void *item)
742 {
743 return ((const struct int_tree_map *)item)->uid;
744 }
745
746 /* Return true if the DECL_UID in both trees are equal. */
747
748 int
749 uid_decl_map_eq (const void *va, const void *vb)
750 {
751 const_tree a = (const_tree) va;
752 const_tree b = (const_tree) vb;
753 return (a->decl_minimal.uid == b->decl_minimal.uid);
754 }
755
756 /* Hash a tree in a uid_decl_map. */
757
758 unsigned int
759 uid_decl_map_hash (const void *item)
760 {
761 return ((const_tree)item)->decl_minimal.uid;
762 }
763
764 /* Return true if the DECL_UID in both trees are equal. */
765
766 static int
767 uid_ssaname_map_eq (const void *va, const void *vb)
768 {
769 const_tree a = (const_tree) va;
770 const_tree b = (const_tree) vb;
771 return (a->ssa_name.var->decl_minimal.uid == b->ssa_name.var->decl_minimal.uid);
772 }
773
774 /* Hash a tree in a uid_decl_map. */
775
776 static unsigned int
777 uid_ssaname_map_hash (const void *item)
778 {
779 return ((const_tree)item)->ssa_name.var->decl_minimal.uid;
780 }
781
782
783 /* Initialize global DFA and SSA structures. */
784
785 void
786 init_tree_ssa (struct function *fn)
787 {
788 fn->gimple_df = GGC_CNEW (struct gimple_df);
789 fn->gimple_df->referenced_vars = htab_create_ggc (20, uid_decl_map_hash,
790 uid_decl_map_eq, NULL);
791 fn->gimple_df->default_defs = htab_create_ggc (20, uid_ssaname_map_hash,
792 uid_ssaname_map_eq, NULL);
793 pt_solution_reset (&fn->gimple_df->escaped);
794 pt_solution_reset (&fn->gimple_df->callused);
795 init_ssanames (fn, 0);
796 init_phinodes ();
797 }
798
799
800 /* Deallocate memory associated with SSA data structures for FNDECL. */
801
802 void
803 delete_tree_ssa (void)
804 {
805 size_t i;
806 basic_block bb;
807 gimple_stmt_iterator gsi;
808 referenced_var_iterator rvi;
809 tree var;
810
811 /* Release any ssa_names still in use. */
812 for (i = 0; i < num_ssa_names; i++)
813 {
814 tree var = ssa_name (i);
815 if (var && TREE_CODE (var) == SSA_NAME)
816 {
817 SSA_NAME_IMM_USE_NODE (var).prev = &(SSA_NAME_IMM_USE_NODE (var));
818 SSA_NAME_IMM_USE_NODE (var).next = &(SSA_NAME_IMM_USE_NODE (var));
819 }
820 release_ssa_name (var);
821 }
822
823 /* FIXME. This may not be necessary. We will release all this
824 memory en masse in free_ssa_operands. This clearing used to be
825 necessary to avoid problems with the inliner, but it may not be
826 needed anymore. */
827 FOR_EACH_BB (bb)
828 {
829 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
830 {
831 gimple stmt = gsi_stmt (gsi);
832
833 if (gimple_has_ops (stmt))
834 {
835 gimple_set_def_ops (stmt, NULL);
836 gimple_set_use_ops (stmt, NULL);
837 gimple_set_addresses_taken (stmt, NULL);
838 }
839
840 if (gimple_has_mem_ops (stmt))
841 {
842 gimple_set_vdef (stmt, NULL_TREE);
843 gimple_set_vuse (stmt, NULL_TREE);
844 }
845
846 gimple_set_modified (stmt, true);
847 }
848 set_phi_nodes (bb, NULL);
849 }
850
851 /* Remove annotations from every referenced local variable. */
852 FOR_EACH_REFERENCED_VAR (var, rvi)
853 {
854 if (is_global_var (var))
855 continue;
856 if (var->base.ann)
857 ggc_free (var->base.ann);
858 var->base.ann = NULL;
859 }
860 htab_delete (gimple_referenced_vars (cfun));
861 cfun->gimple_df->referenced_vars = NULL;
862
863 fini_ssanames ();
864 fini_phinodes ();
865
866 /* We no longer maintain the SSA operand cache at this point. */
867 if (ssa_operands_active ())
868 fini_ssa_operands ();
869
870 delete_alias_heapvars ();
871
872 htab_delete (cfun->gimple_df->default_defs);
873 cfun->gimple_df->default_defs = NULL;
874 pt_solution_reset (&cfun->gimple_df->escaped);
875 pt_solution_reset (&cfun->gimple_df->callused);
876 cfun->gimple_df->modified_noreturn_calls = NULL;
877 cfun->gimple_df = NULL;
878
879 /* We no longer need the edge variable maps. */
880 redirect_edge_var_map_destroy ();
881 }
882
883 /* Helper function for useless_type_conversion_p. */
884
885 static bool
886 useless_type_conversion_p_1 (tree outer_type, tree inner_type)
887 {
888 /* Do the following before stripping toplevel qualifiers. */
889 if (POINTER_TYPE_P (inner_type)
890 && POINTER_TYPE_P (outer_type))
891 {
892 /* Do not lose casts to restrict qualified pointers. */
893 if ((TYPE_RESTRICT (outer_type)
894 != TYPE_RESTRICT (inner_type))
895 && TYPE_RESTRICT (outer_type))
896 return false;
897 }
898
899 /* From now on qualifiers on value types do not matter. */
900 inner_type = TYPE_MAIN_VARIANT (inner_type);
901 outer_type = TYPE_MAIN_VARIANT (outer_type);
902
903 if (inner_type == outer_type)
904 return true;
905
906 /* If we know the canonical types, compare them. */
907 if (TYPE_CANONICAL (inner_type)
908 && TYPE_CANONICAL (inner_type) == TYPE_CANONICAL (outer_type))
909 return true;
910
911 /* Changes in machine mode are never useless conversions. */
912 if (TYPE_MODE (inner_type) != TYPE_MODE (outer_type))
913 return false;
914
915 /* If both the inner and outer types are integral types, then the
916 conversion is not necessary if they have the same mode and
917 signedness and precision, and both or neither are boolean. */
918 if (INTEGRAL_TYPE_P (inner_type)
919 && INTEGRAL_TYPE_P (outer_type))
920 {
921 /* Preserve changes in signedness or precision. */
922 if (TYPE_UNSIGNED (inner_type) != TYPE_UNSIGNED (outer_type)
923 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
924 return false;
925
926 /* Conversions from a non-base to a base type are not useless.
927 This way we preserve the invariant to do arithmetic in
928 base types only. */
929 if (TREE_TYPE (inner_type)
930 && TREE_TYPE (inner_type) != inner_type
931 && (TREE_TYPE (outer_type) == outer_type
932 || TREE_TYPE (outer_type) == NULL_TREE))
933 return false;
934
935 /* We don't need to preserve changes in the types minimum or
936 maximum value in general as these do not generate code
937 unless the types precisions are different. */
938
939 return true;
940 }
941
942 /* Scalar floating point types with the same mode are compatible. */
943 else if (SCALAR_FLOAT_TYPE_P (inner_type)
944 && SCALAR_FLOAT_TYPE_P (outer_type))
945 return true;
946
947 /* We need to take special care recursing to pointed-to types. */
948 else if (POINTER_TYPE_P (inner_type)
949 && POINTER_TYPE_P (outer_type))
950 {
951 /* Don't lose casts between pointers to volatile and non-volatile
952 qualified types. Doing so would result in changing the semantics
953 of later accesses. For function types the volatile qualifier
954 is used to indicate noreturn functions. */
955 if (TREE_CODE (TREE_TYPE (outer_type)) != FUNCTION_TYPE
956 && TREE_CODE (TREE_TYPE (outer_type)) != METHOD_TYPE
957 && TREE_CODE (TREE_TYPE (inner_type)) != FUNCTION_TYPE
958 && TREE_CODE (TREE_TYPE (inner_type)) != METHOD_TYPE
959 && (TYPE_VOLATILE (TREE_TYPE (outer_type))
960 != TYPE_VOLATILE (TREE_TYPE (inner_type)))
961 && TYPE_VOLATILE (TREE_TYPE (outer_type)))
962 return false;
963
964 /* Do not lose casts between pointers with different
965 TYPE_REF_CAN_ALIAS_ALL setting or alias sets. */
966 if ((TYPE_REF_CAN_ALIAS_ALL (inner_type)
967 != TYPE_REF_CAN_ALIAS_ALL (outer_type))
968 || (get_alias_set (TREE_TYPE (inner_type))
969 != get_alias_set (TREE_TYPE (outer_type))))
970 return false;
971
972 /* We do not care for const qualification of the pointed-to types
973 as const qualification has no semantic value to the middle-end. */
974
975 /* Otherwise pointers/references are equivalent if their pointed
976 to types are effectively the same. We can strip qualifiers
977 on pointed-to types for further comparison, which is done in
978 the callee. */
979 return useless_type_conversion_p_1 (TREE_TYPE (outer_type),
980 TREE_TYPE (inner_type));
981 }
982
983 /* Recurse for complex types. */
984 else if (TREE_CODE (inner_type) == COMPLEX_TYPE
985 && TREE_CODE (outer_type) == COMPLEX_TYPE)
986 return useless_type_conversion_p (TREE_TYPE (outer_type),
987 TREE_TYPE (inner_type));
988
989 /* Recurse for vector types with the same number of subparts. */
990 else if (TREE_CODE (inner_type) == VECTOR_TYPE
991 && TREE_CODE (outer_type) == VECTOR_TYPE
992 && TYPE_PRECISION (inner_type) == TYPE_PRECISION (outer_type))
993 return useless_type_conversion_p (TREE_TYPE (outer_type),
994 TREE_TYPE (inner_type));
995
996 /* For aggregates we may need to fall back to structural equality
997 checks. */
998 else if (AGGREGATE_TYPE_P (inner_type)
999 && AGGREGATE_TYPE_P (outer_type))
1000 {
1001 /* Different types of aggregates are incompatible. */
1002 if (TREE_CODE (inner_type) != TREE_CODE (outer_type))
1003 return false;
1004
1005 /* ??? This seems to be necessary even for aggregates that don't
1006 have TYPE_STRUCTURAL_EQUALITY_P set. */
1007
1008 /* ??? This should eventually just return false. */
1009 return lang_hooks.types_compatible_p (inner_type, outer_type);
1010 }
1011 /* Also for functions and possibly other types with
1012 TYPE_STRUCTURAL_EQUALITY_P set. */
1013 else if (TYPE_STRUCTURAL_EQUALITY_P (inner_type)
1014 && TYPE_STRUCTURAL_EQUALITY_P (outer_type))
1015 return lang_hooks.types_compatible_p (inner_type, outer_type);
1016
1017 return false;
1018 }
1019
1020 /* Return true if the conversion from INNER_TYPE to OUTER_TYPE is a
1021 useless type conversion, otherwise return false.
1022
1023 This function implicitly defines the middle-end type system. With
1024 the notion of 'a < b' meaning that useless_type_conversion_p (a, b)
1025 holds and 'a > b' meaning that useless_type_conversion_p (b, a) holds,
1026 the following invariants shall be fulfilled:
1027
1028 1) useless_type_conversion_p is transitive.
1029 If a < b and b < c then a < c.
1030
1031 2) useless_type_conversion_p is not symmetric.
1032 From a < b does not follow a > b.
1033
1034 3) Types define the available set of operations applicable to values.
1035 A type conversion is useless if the operations for the target type
1036 is a subset of the operations for the source type. For example
1037 casts to void* are useless, casts from void* are not (void* can't
1038 be dereferenced or offsetted, but copied, hence its set of operations
1039 is a strict subset of that of all other data pointer types). Casts
1040 to const T* are useless (can't be written to), casts from const T*
1041 to T* are not. */
1042
1043 bool
1044 useless_type_conversion_p (tree outer_type, tree inner_type)
1045 {
1046 /* If the outer type is (void *), then the conversion is not
1047 necessary. We have to make sure to not apply this while
1048 recursing though. */
1049 if (POINTER_TYPE_P (inner_type)
1050 && POINTER_TYPE_P (outer_type)
1051 && TREE_CODE (TREE_TYPE (outer_type)) == VOID_TYPE)
1052 return true;
1053
1054 return useless_type_conversion_p_1 (outer_type, inner_type);
1055 }
1056
1057 /* Return true if a conversion from either type of TYPE1 and TYPE2
1058 to the other is not required. Otherwise return false. */
1059
1060 bool
1061 types_compatible_p (tree type1, tree type2)
1062 {
1063 return (type1 == type2
1064 || (useless_type_conversion_p (type1, type2)
1065 && useless_type_conversion_p (type2, type1)));
1066 }
1067
1068 /* Return true if EXPR is a useless type conversion, otherwise return
1069 false. */
1070
1071 bool
1072 tree_ssa_useless_type_conversion (tree expr)
1073 {
1074 /* If we have an assignment that merely uses a NOP_EXPR to change
1075 the top of the RHS to the type of the LHS and the type conversion
1076 is "safe", then strip away the type conversion so that we can
1077 enter LHS = RHS into the const_and_copies table. */
1078 if (CONVERT_EXPR_P (expr)
1079 || TREE_CODE (expr) == VIEW_CONVERT_EXPR
1080 || TREE_CODE (expr) == NON_LVALUE_EXPR)
1081 return useless_type_conversion_p
1082 (TREE_TYPE (expr),
1083 TREE_TYPE (TREE_OPERAND (expr, 0)));
1084
1085 return false;
1086 }
1087
1088
1089 /* Internal helper for walk_use_def_chains. VAR, FN and DATA are as
1090 described in walk_use_def_chains.
1091
1092 VISITED is a pointer set used to mark visited SSA_NAMEs to avoid
1093 infinite loops. We used to have a bitmap for this to just mark
1094 SSA versions we had visited. But non-sparse bitmaps are way too
1095 expensive, while sparse bitmaps may cause quadratic behavior.
1096
1097 IS_DFS is true if the caller wants to perform a depth-first search
1098 when visiting PHI nodes. A DFS will visit each PHI argument and
1099 call FN after each one. Otherwise, all the arguments are
1100 visited first and then FN is called with each of the visited
1101 arguments in a separate pass. */
1102
1103 static bool
1104 walk_use_def_chains_1 (tree var, walk_use_def_chains_fn fn, void *data,
1105 struct pointer_set_t *visited, bool is_dfs)
1106 {
1107 gimple def_stmt;
1108
1109 if (pointer_set_insert (visited, var))
1110 return false;
1111
1112 def_stmt = SSA_NAME_DEF_STMT (var);
1113
1114 if (gimple_code (def_stmt) != GIMPLE_PHI)
1115 {
1116 /* If we reached the end of the use-def chain, call FN. */
1117 return fn (var, def_stmt, data);
1118 }
1119 else
1120 {
1121 size_t i;
1122
1123 /* When doing a breadth-first search, call FN before following the
1124 use-def links for each argument. */
1125 if (!is_dfs)
1126 for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
1127 if (fn (gimple_phi_arg_def (def_stmt, i), def_stmt, data))
1128 return true;
1129
1130 /* Follow use-def links out of each PHI argument. */
1131 for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
1132 {
1133 tree arg = gimple_phi_arg_def (def_stmt, i);
1134
1135 /* ARG may be NULL for newly introduced PHI nodes. */
1136 if (arg
1137 && TREE_CODE (arg) == SSA_NAME
1138 && walk_use_def_chains_1 (arg, fn, data, visited, is_dfs))
1139 return true;
1140 }
1141
1142 /* When doing a depth-first search, call FN after following the
1143 use-def links for each argument. */
1144 if (is_dfs)
1145 for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
1146 if (fn (gimple_phi_arg_def (def_stmt, i), def_stmt, data))
1147 return true;
1148 }
1149
1150 return false;
1151 }
1152
1153
1154
1155 /* Walk use-def chains starting at the SSA variable VAR. Call
1156 function FN at each reaching definition found. FN takes three
1157 arguments: VAR, its defining statement (DEF_STMT) and a generic
1158 pointer to whatever state information that FN may want to maintain
1159 (DATA). FN is able to stop the walk by returning true, otherwise
1160 in order to continue the walk, FN should return false.
1161
1162 Note, that if DEF_STMT is a PHI node, the semantics are slightly
1163 different. The first argument to FN is no longer the original
1164 variable VAR, but the PHI argument currently being examined. If FN
1165 wants to get at VAR, it should call PHI_RESULT (PHI).
1166
1167 If IS_DFS is true, this function will:
1168
1169 1- walk the use-def chains for all the PHI arguments, and,
1170 2- call (*FN) (ARG, PHI, DATA) on all the PHI arguments.
1171
1172 If IS_DFS is false, the two steps above are done in reverse order
1173 (i.e., a breadth-first search). */
1174
1175 void
1176 walk_use_def_chains (tree var, walk_use_def_chains_fn fn, void *data,
1177 bool is_dfs)
1178 {
1179 gimple def_stmt;
1180
1181 gcc_assert (TREE_CODE (var) == SSA_NAME);
1182
1183 def_stmt = SSA_NAME_DEF_STMT (var);
1184
1185 /* We only need to recurse if the reaching definition comes from a PHI
1186 node. */
1187 if (gimple_code (def_stmt) != GIMPLE_PHI)
1188 (*fn) (var, def_stmt, data);
1189 else
1190 {
1191 struct pointer_set_t *visited = pointer_set_create ();
1192 walk_use_def_chains_1 (var, fn, data, visited, is_dfs);
1193 pointer_set_destroy (visited);
1194 }
1195 }
1196
1197 \f
1198 /* Return true if T, an SSA_NAME, has an undefined value. */
1199
1200 bool
1201 ssa_undefined_value_p (tree t)
1202 {
1203 tree var = SSA_NAME_VAR (t);
1204
1205 /* Parameters get their initial value from the function entry. */
1206 if (TREE_CODE (var) == PARM_DECL)
1207 return false;
1208
1209 /* Hard register variables get their initial value from the ether. */
1210 if (TREE_CODE (var) == VAR_DECL && DECL_HARD_REGISTER (var))
1211 return false;
1212
1213 /* The value is undefined iff its definition statement is empty. */
1214 return gimple_nop_p (SSA_NAME_DEF_STMT (t));
1215 }
1216
1217 /* Emit warnings for uninitialized variables. This is done in two passes.
1218
1219 The first pass notices real uses of SSA names with undefined values.
1220 Such uses are unconditionally uninitialized, and we can be certain that
1221 such a use is a mistake. This pass is run before most optimizations,
1222 so that we catch as many as we can.
1223
1224 The second pass follows PHI nodes to find uses that are potentially
1225 uninitialized. In this case we can't necessarily prove that the use
1226 is really uninitialized. This pass is run after most optimizations,
1227 so that we thread as many jumps and possible, and delete as much dead
1228 code as possible, in order to reduce false positives. We also look
1229 again for plain uninitialized variables, since optimization may have
1230 changed conditionally uninitialized to unconditionally uninitialized. */
1231
1232 /* Emit a warning for T, an SSA_NAME, being uninitialized. The exact
1233 warning text is in MSGID and LOCUS may contain a location or be null. */
1234
1235 static void
1236 warn_uninit (tree t, const char *gmsgid, void *data)
1237 {
1238 tree var = SSA_NAME_VAR (t);
1239 gimple context = (gimple) data;
1240 location_t location;
1241 expanded_location xloc, floc;
1242
1243 if (!ssa_undefined_value_p (t))
1244 return;
1245
1246 /* TREE_NO_WARNING either means we already warned, or the front end
1247 wishes to suppress the warning. */
1248 if (TREE_NO_WARNING (var))
1249 return;
1250
1251 /* Do not warn if it can be initialized outside this module. */
1252 if (is_global_var (var))
1253 return;
1254
1255 location = (context != NULL && gimple_has_location (context))
1256 ? gimple_location (context)
1257 : DECL_SOURCE_LOCATION (var);
1258 xloc = expand_location (location);
1259 floc = expand_location (DECL_SOURCE_LOCATION (cfun->decl));
1260 if (warning_at (location, OPT_Wuninitialized, gmsgid, var))
1261 {
1262 TREE_NO_WARNING (var) = 1;
1263
1264 if (xloc.file != floc.file
1265 || xloc.line < floc.line
1266 || xloc.line > LOCATION_LINE (cfun->function_end_locus))
1267 inform (input_location, "%J%qD was declared here", var, var);
1268 }
1269 }
1270
1271 struct walk_data {
1272 gimple stmt;
1273 bool always_executed;
1274 bool warn_possibly_uninitialized;
1275 };
1276
1277 /* Called via walk_tree, look for SSA_NAMEs that have empty definitions
1278 and warn about them. */
1279
1280 static tree
1281 warn_uninitialized_var (tree *tp, int *walk_subtrees, void *data_)
1282 {
1283 struct walk_stmt_info *wi = (struct walk_stmt_info *) data_;
1284 struct walk_data *data = (struct walk_data *) wi->info;
1285 tree t = *tp;
1286
1287 /* We do not care about LHS. */
1288 if (wi->is_lhs)
1289 return NULL_TREE;
1290
1291 switch (TREE_CODE (t))
1292 {
1293 case ADDR_EXPR:
1294 /* Taking the address of an uninitialized variable does not
1295 count as using it. */
1296 *walk_subtrees = 0;
1297 break;
1298
1299 case VAR_DECL:
1300 {
1301 /* A VAR_DECL in the RHS of a gimple statement may mean that
1302 this variable is loaded from memory. */
1303 use_operand_p vuse;
1304 tree op;
1305
1306 /* If there is not gimple stmt,
1307 or alias information has not been computed,
1308 then we cannot check VUSE ops. */
1309 if (data->stmt == NULL)
1310 return NULL_TREE;
1311
1312 /* If the load happens as part of a call do not warn about it. */
1313 if (is_gimple_call (data->stmt))
1314 return NULL_TREE;
1315
1316 vuse = gimple_vuse_op (data->stmt);
1317 if (vuse == NULL_USE_OPERAND_P)
1318 return NULL_TREE;
1319
1320 op = USE_FROM_PTR (vuse);
1321 if (t != SSA_NAME_VAR (op)
1322 || !SSA_NAME_IS_DEFAULT_DEF (op))
1323 return NULL_TREE;
1324 /* If this is a VUSE of t and it is the default definition,
1325 then warn about op. */
1326 t = op;
1327 /* Fall through into SSA_NAME. */
1328 }
1329
1330 case SSA_NAME:
1331 /* We only do data flow with SSA_NAMEs, so that's all we
1332 can warn about. */
1333 if (data->always_executed)
1334 warn_uninit (t, "%qD is used uninitialized in this function",
1335 data->stmt);
1336 else if (data->warn_possibly_uninitialized)
1337 warn_uninit (t, "%qD may be used uninitialized in this function",
1338 data->stmt);
1339 *walk_subtrees = 0;
1340 break;
1341
1342 case REALPART_EXPR:
1343 case IMAGPART_EXPR:
1344 /* The total store transformation performed during gimplification
1345 creates uninitialized variable uses. If all is well, these will
1346 be optimized away, so don't warn now. */
1347 if (TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME)
1348 *walk_subtrees = 0;
1349 break;
1350
1351 default:
1352 if (IS_TYPE_OR_DECL_P (t))
1353 *walk_subtrees = 0;
1354 break;
1355 }
1356
1357 return NULL_TREE;
1358 }
1359
1360 /* Look for inputs to PHI that are SSA_NAMEs that have empty definitions
1361 and warn about them. */
1362
1363 static void
1364 warn_uninitialized_phi (gimple phi)
1365 {
1366 size_t i, n = gimple_phi_num_args (phi);
1367
1368 /* Don't look at memory tags. */
1369 if (!is_gimple_reg (gimple_phi_result (phi)))
1370 return;
1371
1372 for (i = 0; i < n; ++i)
1373 {
1374 tree op = gimple_phi_arg_def (phi, i);
1375 if (TREE_CODE (op) == SSA_NAME)
1376 warn_uninit (op, "%qD may be used uninitialized in this function",
1377 NULL);
1378 }
1379 }
1380
1381 static unsigned int
1382 warn_uninitialized_vars (bool warn_possibly_uninitialized)
1383 {
1384 gimple_stmt_iterator gsi;
1385 basic_block bb;
1386 struct walk_data data;
1387
1388 data.warn_possibly_uninitialized = warn_possibly_uninitialized;
1389
1390 calculate_dominance_info (CDI_POST_DOMINATORS);
1391
1392 FOR_EACH_BB (bb)
1393 {
1394 data.always_executed = dominated_by_p (CDI_POST_DOMINATORS,
1395 single_succ (ENTRY_BLOCK_PTR), bb);
1396 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1397 {
1398 struct walk_stmt_info wi;
1399 data.stmt = gsi_stmt (gsi);
1400 memset (&wi, 0, sizeof (wi));
1401 wi.info = &data;
1402 walk_gimple_op (gsi_stmt (gsi), warn_uninitialized_var, &wi);
1403 }
1404 }
1405
1406 /* Post-dominator information can not be reliably updated. Free it
1407 after the use. */
1408
1409 free_dominance_info (CDI_POST_DOMINATORS);
1410 return 0;
1411 }
1412
1413 static unsigned int
1414 execute_early_warn_uninitialized (void)
1415 {
1416 /* Currently, this pass runs always but
1417 execute_late_warn_uninitialized only runs with optimization. With
1418 optimization we want to warn about possible uninitialized as late
1419 as possible, thus don't do it here. However, without
1420 optimization we need to warn here about "may be uninitialized".
1421 */
1422 warn_uninitialized_vars (/*warn_possibly_uninitialized=*/!optimize);
1423 return 0;
1424 }
1425
1426 static unsigned int
1427 execute_late_warn_uninitialized (void)
1428 {
1429 basic_block bb;
1430 gimple_stmt_iterator gsi;
1431
1432 /* Re-do the plain uninitialized variable check, as optimization may have
1433 straightened control flow. Do this first so that we don't accidentally
1434 get a "may be" warning when we'd have seen an "is" warning later. */
1435 warn_uninitialized_vars (/*warn_possibly_uninitialized=*/1);
1436
1437 FOR_EACH_BB (bb)
1438 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1439 warn_uninitialized_phi (gsi_stmt (gsi));
1440
1441 return 0;
1442 }
1443
1444 static bool
1445 gate_warn_uninitialized (void)
1446 {
1447 return warn_uninitialized != 0;
1448 }
1449
1450 struct gimple_opt_pass pass_early_warn_uninitialized =
1451 {
1452 {
1453 GIMPLE_PASS,
1454 NULL, /* name */
1455 gate_warn_uninitialized, /* gate */
1456 execute_early_warn_uninitialized, /* execute */
1457 NULL, /* sub */
1458 NULL, /* next */
1459 0, /* static_pass_number */
1460 0, /* tv_id */
1461 PROP_ssa, /* properties_required */
1462 0, /* properties_provided */
1463 0, /* properties_destroyed */
1464 0, /* todo_flags_start */
1465 0 /* todo_flags_finish */
1466 }
1467 };
1468
1469 struct gimple_opt_pass pass_late_warn_uninitialized =
1470 {
1471 {
1472 GIMPLE_PASS,
1473 NULL, /* name */
1474 gate_warn_uninitialized, /* gate */
1475 execute_late_warn_uninitialized, /* execute */
1476 NULL, /* sub */
1477 NULL, /* next */
1478 0, /* static_pass_number */
1479 0, /* tv_id */
1480 PROP_ssa, /* properties_required */
1481 0, /* properties_provided */
1482 0, /* properties_destroyed */
1483 0, /* todo_flags_start */
1484 0 /* todo_flags_finish */
1485 }
1486 };
1487
1488 /* Compute TREE_ADDRESSABLE and DECL_GIMPLE_REG_P for local variables. */
1489
1490 void
1491 execute_update_addresses_taken (bool do_optimize)
1492 {
1493 tree var;
1494 referenced_var_iterator rvi;
1495 gimple_stmt_iterator gsi;
1496 basic_block bb;
1497 bitmap addresses_taken = BITMAP_ALLOC (NULL);
1498 bitmap not_reg_needs = BITMAP_ALLOC (NULL);
1499 bool update_vops = false;
1500
1501 /* Collect into ADDRESSES_TAKEN all variables whose address is taken within
1502 the function body. */
1503 FOR_EACH_BB (bb)
1504 {
1505 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1506 {
1507 const_gimple stmt = gsi_stmt (gsi);
1508 enum gimple_code code = gimple_code (stmt);
1509 bitmap taken = gimple_addresses_taken (stmt);
1510
1511 if (taken)
1512 bitmap_ior_into (addresses_taken, taken);
1513
1514 /* If we have a call or an assignment, see if the lhs contains
1515 a local decl that requires not to be a gimple register. */
1516 if (code == GIMPLE_ASSIGN || code == GIMPLE_CALL)
1517 {
1518 tree lhs = gimple_get_lhs (stmt);
1519 /* A plain decl does not need it set. */
1520 if (lhs && handled_component_p (lhs))
1521 {
1522 var = get_base_address (lhs);
1523 if (DECL_P (var))
1524 bitmap_set_bit (not_reg_needs, DECL_UID (var));
1525 }
1526 }
1527 }
1528
1529 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1530 {
1531 size_t i;
1532 gimple phi = gsi_stmt (gsi);
1533
1534 for (i = 0; i < gimple_phi_num_args (phi); i++)
1535 {
1536 tree op = PHI_ARG_DEF (phi, i), var;
1537 if (TREE_CODE (op) == ADDR_EXPR
1538 && (var = get_base_address (TREE_OPERAND (op, 0))) != NULL
1539 && DECL_P (var))
1540 bitmap_set_bit (addresses_taken, DECL_UID (var));
1541 }
1542 }
1543 }
1544
1545 /* When possible, clear ADDRESSABLE bit or set the REGISTER bit
1546 and mark variable for conversion into SSA. */
1547 if (optimize && do_optimize)
1548 FOR_EACH_REFERENCED_VAR (var, rvi)
1549 {
1550 /* Global Variables, result decls cannot be changed. */
1551 if (is_global_var (var)
1552 || TREE_CODE (var) == RESULT_DECL
1553 || bitmap_bit_p (addresses_taken, DECL_UID (var)))
1554 continue;
1555
1556 if (TREE_ADDRESSABLE (var)
1557 /* Do not change TREE_ADDRESSABLE if we need to preserve var as
1558 a non-register. Otherwise we are confused and forget to
1559 add virtual operands for it. */
1560 && (!is_gimple_reg_type (TREE_TYPE (var))
1561 || !bitmap_bit_p (not_reg_needs, DECL_UID (var))))
1562 {
1563 TREE_ADDRESSABLE (var) = 0;
1564 if (is_gimple_reg (var))
1565 mark_sym_for_renaming (var);
1566 update_vops = true;
1567 if (dump_file)
1568 {
1569 fprintf (dump_file, "No longer having address taken ");
1570 print_generic_expr (dump_file, var, 0);
1571 fprintf (dump_file, "\n");
1572 }
1573 }
1574 if (!DECL_GIMPLE_REG_P (var)
1575 && !bitmap_bit_p (not_reg_needs, DECL_UID (var))
1576 && (TREE_CODE (TREE_TYPE (var)) == COMPLEX_TYPE
1577 || TREE_CODE (TREE_TYPE (var)) == VECTOR_TYPE))
1578 {
1579 DECL_GIMPLE_REG_P (var) = 1;
1580 mark_sym_for_renaming (var);
1581 update_vops = true;
1582 if (dump_file)
1583 {
1584 fprintf (dump_file, "Decl is now a gimple register ");
1585 print_generic_expr (dump_file, var, 0);
1586 fprintf (dump_file, "\n");
1587 }
1588 }
1589 }
1590
1591 /* Operand caches needs to be recomputed for operands referencing the updated
1592 variables. */
1593 if (update_vops)
1594 {
1595 FOR_EACH_BB (bb)
1596 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1597 {
1598 gimple stmt = gsi_stmt (gsi);
1599
1600 if (gimple_references_memory_p (stmt))
1601 update_stmt (stmt);
1602 }
1603
1604 /* Update SSA form here, we are called as non-pass as well. */
1605 update_ssa (TODO_update_ssa);
1606 }
1607
1608 BITMAP_FREE (not_reg_needs);
1609 BITMAP_FREE (addresses_taken);
1610 }
1611
1612 struct gimple_opt_pass pass_update_address_taken =
1613 {
1614 {
1615 GIMPLE_PASS,
1616 "addressables", /* name */
1617 NULL, /* gate */
1618 NULL, /* execute */
1619 NULL, /* sub */
1620 NULL, /* next */
1621 0, /* static_pass_number */
1622 0, /* tv_id */
1623 PROP_ssa, /* properties_required */
1624 0, /* properties_provided */
1625 0, /* properties_destroyed */
1626 0, /* todo_flags_start */
1627 TODO_update_address_taken
1628 | TODO_dump_func /* todo_flags_finish */
1629 }
1630 };