* fr.po: Update.
[official-gcc.git] / gcc / tree-ssa-live.c
blob0b992dba1300103931fbef417c064a56bda98ac7
1 /* Liveness for SSA trees.
2 Copyright (C) 2003-2017 Free Software Foundation, Inc.
3 Contributed by Andrew MacLeod <amacleod@redhat.com>
5 This file is part of GCC.
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.
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.
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/>. */
21 #include "config.h"
22 #include "system.h"
23 #include "coretypes.h"
24 #include "backend.h"
25 #include "rtl.h"
26 #include "tree.h"
27 #include "gimple.h"
28 #include "timevar.h"
29 #include "ssa.h"
30 #include "cgraph.h"
31 #include "gimple-pretty-print.h"
32 #include "diagnostic-core.h"
33 #include "gimple-iterator.h"
34 #include "tree-dfa.h"
35 #include "dumpfile.h"
36 #include "tree-ssa-live.h"
37 #include "debug.h"
38 #include "tree-ssa.h"
39 #include "ipa-utils.h"
40 #include "cfgloop.h"
42 static void verify_live_on_entry (tree_live_info_p);
45 /* VARMAP maintains a mapping from SSA version number to real variables.
47 All SSA_NAMES are divided into partitions. Initially each ssa_name is the
48 only member of it's own partition. Coalescing will attempt to group any
49 ssa_names which occur in a copy or in a PHI node into the same partition.
51 At the end of out-of-ssa, each partition becomes a "real" variable and is
52 rewritten as a compiler variable.
54 The var_map data structure is used to manage these partitions. It allows
55 partitions to be combined, and determines which partition belongs to what
56 ssa_name or variable, and vice versa. */
59 /* Remove the base table in MAP. */
61 static void
62 var_map_base_fini (var_map map)
64 /* Free the basevar info if it is present. */
65 if (map->partition_to_base_index != NULL)
67 free (map->partition_to_base_index);
68 map->partition_to_base_index = NULL;
69 map->num_basevars = 0;
72 /* Create a variable partition map of SIZE, initialize and return it. */
74 var_map
75 init_var_map (int size)
77 var_map map;
79 map = (var_map) xmalloc (sizeof (struct _var_map));
80 map->var_partition = partition_new (size);
82 map->partition_to_view = NULL;
83 map->view_to_partition = NULL;
84 map->num_partitions = size;
85 map->partition_size = size;
86 map->num_basevars = 0;
87 map->partition_to_base_index = NULL;
88 return map;
92 /* Free memory associated with MAP. */
94 void
95 delete_var_map (var_map map)
97 var_map_base_fini (map);
98 partition_delete (map->var_partition);
99 free (map->partition_to_view);
100 free (map->view_to_partition);
101 free (map);
105 /* This function will combine the partitions in MAP for VAR1 and VAR2. It
106 Returns the partition which represents the new partition. If the two
107 partitions cannot be combined, NO_PARTITION is returned. */
110 var_union (var_map map, tree var1, tree var2)
112 int p1, p2, p3;
114 gcc_assert (TREE_CODE (var1) == SSA_NAME);
115 gcc_assert (TREE_CODE (var2) == SSA_NAME);
117 /* This is independent of partition_to_view. If partition_to_view is
118 on, then whichever one of these partitions is absorbed will never have a
119 dereference into the partition_to_view array any more. */
121 p1 = partition_find (map->var_partition, SSA_NAME_VERSION (var1));
122 p2 = partition_find (map->var_partition, SSA_NAME_VERSION (var2));
124 gcc_assert (p1 != NO_PARTITION);
125 gcc_assert (p2 != NO_PARTITION);
127 if (p1 == p2)
128 p3 = p1;
129 else
130 p3 = partition_union (map->var_partition, p1, p2);
132 if (map->partition_to_view)
133 p3 = map->partition_to_view[p3];
135 return p3;
139 /* Compress the partition numbers in MAP such that they fall in the range
140 0..(num_partitions-1) instead of wherever they turned out during
141 the partitioning exercise. This removes any references to unused
142 partitions, thereby allowing bitmaps and other vectors to be much
143 denser.
145 This is implemented such that compaction doesn't affect partitioning.
146 Ie., once partitions are created and possibly merged, running one
147 or more different kind of compaction will not affect the partitions
148 themselves. Their index might change, but all the same variables will
149 still be members of the same partition group. This allows work on reduced
150 sets, and no loss of information when a larger set is later desired.
152 In particular, coalescing can work on partitions which have 2 or more
153 definitions, and then 'recompact' later to include all the single
154 definitions for assignment to program variables. */
157 /* Set MAP back to the initial state of having no partition view. Return a
158 bitmap which has a bit set for each partition number which is in use in the
159 varmap. */
161 static bitmap
162 partition_view_init (var_map map)
164 bitmap used;
165 int tmp;
166 unsigned int x;
168 used = BITMAP_ALLOC (NULL);
170 /* Already in a view? Abandon the old one. */
171 if (map->partition_to_view)
173 free (map->partition_to_view);
174 map->partition_to_view = NULL;
176 if (map->view_to_partition)
178 free (map->view_to_partition);
179 map->view_to_partition = NULL;
182 /* Find out which partitions are actually referenced. */
183 for (x = 0; x < map->partition_size; x++)
185 tmp = partition_find (map->var_partition, x);
186 if (ssa_name (tmp) != NULL_TREE && !virtual_operand_p (ssa_name (tmp))
187 && (!has_zero_uses (ssa_name (tmp))
188 || !SSA_NAME_IS_DEFAULT_DEF (ssa_name (tmp))
189 || (SSA_NAME_VAR (ssa_name (tmp))
190 && !VAR_P (SSA_NAME_VAR (ssa_name (tmp))))))
191 bitmap_set_bit (used, tmp);
194 map->num_partitions = map->partition_size;
195 return used;
199 /* This routine will finalize the view data for MAP based on the partitions
200 set in SELECTED. This is either the same bitmap returned from
201 partition_view_init, or a trimmed down version if some of those partitions
202 were not desired in this view. SELECTED is freed before returning. */
204 static void
205 partition_view_fini (var_map map, bitmap selected)
207 bitmap_iterator bi;
208 unsigned count, i, x, limit;
210 gcc_assert (selected);
212 count = bitmap_count_bits (selected);
213 limit = map->partition_size;
215 /* If its a one-to-one ratio, we don't need any view compaction. */
216 if (count < limit)
218 map->partition_to_view = (int *)xmalloc (limit * sizeof (int));
219 memset (map->partition_to_view, 0xff, (limit * sizeof (int)));
220 map->view_to_partition = (int *)xmalloc (count * sizeof (int));
222 i = 0;
223 /* Give each selected partition an index. */
224 EXECUTE_IF_SET_IN_BITMAP (selected, 0, x, bi)
226 map->partition_to_view[x] = i;
227 map->view_to_partition[i] = x;
228 i++;
230 gcc_assert (i == count);
231 map->num_partitions = i;
234 BITMAP_FREE (selected);
238 /* Create a partition view which includes all the used partitions in MAP. */
240 void
241 partition_view_normal (var_map map)
243 bitmap used;
245 used = partition_view_init (map);
246 partition_view_fini (map, used);
248 var_map_base_fini (map);
252 /* Create a partition view in MAP which includes just partitions which occur in
253 the bitmap ONLY. If WANT_BASES is true, create the base variable map
254 as well. */
256 void
257 partition_view_bitmap (var_map map, bitmap only)
259 bitmap used;
260 bitmap new_partitions = BITMAP_ALLOC (NULL);
261 unsigned x, p;
262 bitmap_iterator bi;
264 used = partition_view_init (map);
265 EXECUTE_IF_SET_IN_BITMAP (only, 0, x, bi)
267 p = partition_find (map->var_partition, x);
268 gcc_assert (bitmap_bit_p (used, p));
269 bitmap_set_bit (new_partitions, p);
271 partition_view_fini (map, new_partitions);
273 var_map_base_fini (map);
277 static bitmap usedvars;
279 /* Mark VAR as used, so that it'll be preserved during rtl expansion.
280 Returns true if VAR wasn't marked before. */
282 static inline bool
283 set_is_used (tree var)
285 return bitmap_set_bit (usedvars, DECL_UID (var));
288 /* Return true if VAR is marked as used. */
290 static inline bool
291 is_used_p (tree var)
293 return bitmap_bit_p (usedvars, DECL_UID (var));
296 static inline void mark_all_vars_used (tree *);
298 /* Helper function for mark_all_vars_used, called via walk_tree. */
300 static tree
301 mark_all_vars_used_1 (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
303 tree t = *tp;
304 enum tree_code_class c = TREE_CODE_CLASS (TREE_CODE (t));
305 tree b;
307 if (TREE_CODE (t) == SSA_NAME)
309 *walk_subtrees = 0;
310 t = SSA_NAME_VAR (t);
311 if (!t)
312 return NULL;
315 if (IS_EXPR_CODE_CLASS (c)
316 && (b = TREE_BLOCK (t)) != NULL)
317 TREE_USED (b) = true;
319 /* Ignore TMR_OFFSET and TMR_STEP for TARGET_MEM_REFS, as those
320 fields do not contain vars. */
321 if (TREE_CODE (t) == TARGET_MEM_REF)
323 mark_all_vars_used (&TMR_BASE (t));
324 mark_all_vars_used (&TMR_INDEX (t));
325 mark_all_vars_used (&TMR_INDEX2 (t));
326 *walk_subtrees = 0;
327 return NULL;
330 /* Only need to mark VAR_DECLS; parameters and return results are not
331 eliminated as unused. */
332 if (VAR_P (t))
334 /* When a global var becomes used for the first time also walk its
335 initializer (non global ones don't have any). */
336 if (set_is_used (t) && is_global_var (t)
337 && DECL_CONTEXT (t) == current_function_decl)
338 mark_all_vars_used (&DECL_INITIAL (t));
340 /* remove_unused_scope_block_p requires information about labels
341 which are not DECL_IGNORED_P to tell if they might be used in the IL. */
342 else if (TREE_CODE (t) == LABEL_DECL)
343 /* Although the TREE_USED values that the frontend uses would be
344 acceptable (albeit slightly over-conservative) for our purposes,
345 init_vars_expansion clears TREE_USED for LABEL_DECLs too, so we
346 must re-compute it here. */
347 TREE_USED (t) = 1;
349 if (IS_TYPE_OR_DECL_P (t))
350 *walk_subtrees = 0;
352 return NULL;
355 /* Mark the scope block SCOPE and its subblocks unused when they can be
356 possibly eliminated if dead. */
358 static void
359 mark_scope_block_unused (tree scope)
361 tree t;
362 TREE_USED (scope) = false;
363 if (!(*debug_hooks->ignore_block) (scope))
364 TREE_USED (scope) = true;
365 for (t = BLOCK_SUBBLOCKS (scope); t ; t = BLOCK_CHAIN (t))
366 mark_scope_block_unused (t);
369 /* Look if the block is dead (by possibly eliminating its dead subblocks)
370 and return true if so.
371 Block is declared dead if:
372 1) No statements are associated with it.
373 2) Declares no live variables
374 3) All subblocks are dead
375 or there is precisely one subblocks and the block
376 has same abstract origin as outer block and declares
377 no variables, so it is pure wrapper.
378 When we are not outputting full debug info, we also eliminate dead variables
379 out of scope blocks to let them to be recycled by GGC and to save copying work
380 done by the inliner. */
382 static bool
383 remove_unused_scope_block_p (tree scope, bool in_ctor_dtor_block)
385 tree *t, *next;
386 bool unused = !TREE_USED (scope);
387 int nsubblocks = 0;
389 /* For ipa-polymorphic-call.c purposes, preserve blocks:
390 1) with BLOCK_ABSTRACT_ORIGIN of a ctor/dtor or their clones */
391 if (inlined_polymorphic_ctor_dtor_block_p (scope, true))
393 in_ctor_dtor_block = true;
394 unused = false;
396 /* 2) inside such blocks, the outermost block with block_ultimate_origin
397 being a FUNCTION_DECL. */
398 else if (in_ctor_dtor_block)
400 tree fn = block_ultimate_origin (scope);
401 if (fn && TREE_CODE (fn) == FUNCTION_DECL)
403 in_ctor_dtor_block = false;
404 unused = false;
408 for (t = &BLOCK_VARS (scope); *t; t = next)
410 next = &DECL_CHAIN (*t);
412 /* Debug info of nested function refers to the block of the
413 function. We might stil call it even if all statements
414 of function it was nested into was elliminated.
416 TODO: We can actually look into cgraph to see if function
417 will be output to file. */
418 if (TREE_CODE (*t) == FUNCTION_DECL)
419 unused = false;
421 /* If a decl has a value expr, we need to instantiate it
422 regardless of debug info generation, to avoid codegen
423 differences in memory overlap tests. update_equiv_regs() may
424 indirectly call validate_equiv_mem() to test whether a
425 SET_DEST overlaps with others, and if the value expr changes
426 by virtual register instantiation, we may get end up with
427 different results. */
428 else if (VAR_P (*t) && DECL_HAS_VALUE_EXPR_P (*t))
429 unused = false;
431 /* Remove everything we don't generate debug info for. */
432 else if (DECL_IGNORED_P (*t))
434 *t = DECL_CHAIN (*t);
435 next = t;
438 /* When we are outputting debug info, we usually want to output
439 info about optimized-out variables in the scope blocks.
440 Exception are the scope blocks not containing any instructions
441 at all so user can't get into the scopes at first place. */
442 else if (is_used_p (*t))
443 unused = false;
444 else if (TREE_CODE (*t) == LABEL_DECL && TREE_USED (*t))
445 /* For labels that are still used in the IL, the decision to
446 preserve them must not depend DEBUG_INFO_LEVEL, otherwise we
447 risk having different ordering in debug vs. non-debug builds
448 during inlining or versioning.
449 A label appearing here (we have already checked DECL_IGNORED_P)
450 should not be used in the IL unless it has been explicitly used
451 before, so we use TREE_USED as an approximation. */
452 /* In principle, we should do the same here as for the debug case
453 below, however, when debugging, there might be additional nested
454 levels that keep an upper level with a label live, so we have to
455 force this block to be considered used, too. */
456 unused = false;
458 /* When we are not doing full debug info, we however can keep around
459 only the used variables for cfgexpand's memory packing saving quite
460 a lot of memory.
462 For sake of -g3, we keep around those vars but we don't count this as
463 use of block, so innermost block with no used vars and no instructions
464 can be considered dead. We only want to keep around blocks user can
465 breakpoint into and ask about value of optimized out variables.
467 Similarly we need to keep around types at least until all
468 variables of all nested blocks are gone. We track no
469 information on whether given type is used or not, so we have
470 to keep them even when not emitting debug information,
471 otherwise we may end up remapping variables and their (local)
472 types in different orders depending on whether debug
473 information is being generated. */
475 else if (TREE_CODE (*t) == TYPE_DECL
476 || debug_info_level == DINFO_LEVEL_NORMAL
477 || debug_info_level == DINFO_LEVEL_VERBOSE)
479 else
481 *t = DECL_CHAIN (*t);
482 next = t;
486 for (t = &BLOCK_SUBBLOCKS (scope); *t ;)
487 if (remove_unused_scope_block_p (*t, in_ctor_dtor_block))
489 if (BLOCK_SUBBLOCKS (*t))
491 tree next = BLOCK_CHAIN (*t);
492 tree supercontext = BLOCK_SUPERCONTEXT (*t);
494 *t = BLOCK_SUBBLOCKS (*t);
495 while (BLOCK_CHAIN (*t))
497 BLOCK_SUPERCONTEXT (*t) = supercontext;
498 t = &BLOCK_CHAIN (*t);
500 BLOCK_CHAIN (*t) = next;
501 BLOCK_SUPERCONTEXT (*t) = supercontext;
502 t = &BLOCK_CHAIN (*t);
503 nsubblocks ++;
505 else
506 *t = BLOCK_CHAIN (*t);
508 else
510 t = &BLOCK_CHAIN (*t);
511 nsubblocks ++;
515 if (!unused)
517 /* Outer scope is always used. */
518 else if (!BLOCK_SUPERCONTEXT (scope)
519 || TREE_CODE (BLOCK_SUPERCONTEXT (scope)) == FUNCTION_DECL)
520 unused = false;
521 /* Innermost blocks with no live variables nor statements can be always
522 eliminated. */
523 else if (!nsubblocks)
525 /* When not generating debug info we can eliminate info on unused
526 variables. */
527 else if (!flag_auto_profile && debug_info_level == DINFO_LEVEL_NONE)
529 /* Even for -g0 don't prune outer scopes from artificial
530 functions, otherwise diagnostics using tree_nonartificial_location
531 will not be emitted properly. */
532 if (inlined_function_outer_scope_p (scope))
534 tree ao = scope;
536 while (ao
537 && TREE_CODE (ao) == BLOCK
538 && BLOCK_ABSTRACT_ORIGIN (ao) != ao)
539 ao = BLOCK_ABSTRACT_ORIGIN (ao);
540 if (ao
541 && TREE_CODE (ao) == FUNCTION_DECL
542 && DECL_DECLARED_INLINE_P (ao)
543 && lookup_attribute ("artificial", DECL_ATTRIBUTES (ao)))
544 unused = false;
547 else if (BLOCK_VARS (scope) || BLOCK_NUM_NONLOCALIZED_VARS (scope))
548 unused = false;
549 /* See if this block is important for representation of inlined function.
550 Inlined functions are always represented by block with
551 block_ultimate_origin being set to FUNCTION_DECL and DECL_SOURCE_LOCATION
552 set... */
553 else if (inlined_function_outer_scope_p (scope))
554 unused = false;
555 else
556 /* Verfify that only blocks with source location set
557 are entry points to the inlined functions. */
558 gcc_assert (LOCATION_LOCUS (BLOCK_SOURCE_LOCATION (scope))
559 == UNKNOWN_LOCATION);
561 TREE_USED (scope) = !unused;
562 return unused;
565 /* Mark all VAR_DECLS under *EXPR_P as used, so that they won't be
566 eliminated during the tree->rtl conversion process. */
568 static inline void
569 mark_all_vars_used (tree *expr_p)
571 walk_tree (expr_p, mark_all_vars_used_1, NULL, NULL);
574 /* Helper function for clear_unused_block_pointer, called via walk_tree. */
576 static tree
577 clear_unused_block_pointer_1 (tree *tp, int *, void *)
579 if (EXPR_P (*tp) && TREE_BLOCK (*tp)
580 && !TREE_USED (TREE_BLOCK (*tp)))
581 TREE_SET_BLOCK (*tp, NULL);
582 return NULL_TREE;
585 /* Set all block pointer in debug or clobber stmt to NULL if the block
586 is unused, so that they will not be streamed out. */
588 static void
589 clear_unused_block_pointer (void)
591 basic_block bb;
592 gimple_stmt_iterator gsi;
594 FOR_EACH_BB_FN (bb, cfun)
595 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
597 unsigned i;
598 tree b;
599 gimple *stmt = gsi_stmt (gsi);
601 if (!is_gimple_debug (stmt) && !gimple_clobber_p (stmt))
602 continue;
603 b = gimple_block (stmt);
604 if (b && !TREE_USED (b))
605 gimple_set_block (stmt, NULL);
606 for (i = 0; i < gimple_num_ops (stmt); i++)
607 walk_tree (gimple_op_ptr (stmt, i), clear_unused_block_pointer_1,
608 NULL, NULL);
612 /* Dump scope blocks starting at SCOPE to FILE. INDENT is the
613 indentation level and FLAGS is as in print_generic_expr. */
615 static void
616 dump_scope_block (FILE *file, int indent, tree scope, int flags)
618 tree var, t;
619 unsigned int i;
621 fprintf (file, "\n%*s{ Scope block #%i%s%s",indent, "" , BLOCK_NUMBER (scope),
622 TREE_USED (scope) ? "" : " (unused)",
623 BLOCK_ABSTRACT (scope) ? " (abstract)": "");
624 if (LOCATION_LOCUS (BLOCK_SOURCE_LOCATION (scope)) != UNKNOWN_LOCATION)
626 expanded_location s = expand_location (BLOCK_SOURCE_LOCATION (scope));
627 fprintf (file, " %s:%i", s.file, s.line);
629 if (BLOCK_ABSTRACT_ORIGIN (scope))
631 tree origin = block_ultimate_origin (scope);
632 if (origin)
634 fprintf (file, " Originating from :");
635 if (DECL_P (origin))
636 print_generic_decl (file, origin, flags);
637 else
638 fprintf (file, "#%i", BLOCK_NUMBER (origin));
641 fprintf (file, " \n");
642 for (var = BLOCK_VARS (scope); var; var = DECL_CHAIN (var))
644 fprintf (file, "%*s", indent, "");
645 print_generic_decl (file, var, flags);
646 fprintf (file, "\n");
648 for (i = 0; i < BLOCK_NUM_NONLOCALIZED_VARS (scope); i++)
650 fprintf (file, "%*s",indent, "");
651 print_generic_decl (file, BLOCK_NONLOCALIZED_VAR (scope, i),
652 flags);
653 fprintf (file, " (nonlocalized)\n");
655 for (t = BLOCK_SUBBLOCKS (scope); t ; t = BLOCK_CHAIN (t))
656 dump_scope_block (file, indent + 2, t, flags);
657 fprintf (file, "\n%*s}\n",indent, "");
660 /* Dump the tree of lexical scopes starting at SCOPE to stderr. FLAGS
661 is as in print_generic_expr. */
663 DEBUG_FUNCTION void
664 debug_scope_block (tree scope, int flags)
666 dump_scope_block (stderr, 0, scope, flags);
670 /* Dump the tree of lexical scopes of current_function_decl to FILE.
671 FLAGS is as in print_generic_expr. */
673 void
674 dump_scope_blocks (FILE *file, int flags)
676 dump_scope_block (file, 0, DECL_INITIAL (current_function_decl), flags);
680 /* Dump the tree of lexical scopes of current_function_decl to stderr.
681 FLAGS is as in print_generic_expr. */
683 DEBUG_FUNCTION void
684 debug_scope_blocks (int flags)
686 dump_scope_blocks (stderr, flags);
689 /* Remove local variables that are not referenced in the IL. */
691 void
692 remove_unused_locals (void)
694 basic_block bb;
695 tree var;
696 unsigned srcidx, dstidx, num;
697 bool have_local_clobbers = false;
699 /* Removing declarations from lexical blocks when not optimizing is
700 not only a waste of time, it actually causes differences in stack
701 layout. */
702 if (!optimize)
703 return;
705 timevar_push (TV_REMOVE_UNUSED);
707 mark_scope_block_unused (DECL_INITIAL (current_function_decl));
709 usedvars = BITMAP_ALLOC (NULL);
711 /* Walk the CFG marking all referenced symbols. */
712 FOR_EACH_BB_FN (bb, cfun)
714 gimple_stmt_iterator gsi;
715 size_t i;
716 edge_iterator ei;
717 edge e;
719 /* Walk the statements. */
720 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
722 gimple *stmt = gsi_stmt (gsi);
723 tree b = gimple_block (stmt);
725 if (is_gimple_debug (stmt))
726 continue;
728 if (gimple_clobber_p (stmt))
730 have_local_clobbers = true;
731 continue;
734 if (b)
735 TREE_USED (b) = true;
737 for (i = 0; i < gimple_num_ops (stmt); i++)
738 mark_all_vars_used (gimple_op_ptr (gsi_stmt (gsi), i));
741 for (gphi_iterator gpi = gsi_start_phis (bb);
742 !gsi_end_p (gpi);
743 gsi_next (&gpi))
745 use_operand_p arg_p;
746 ssa_op_iter i;
747 tree def;
748 gphi *phi = gpi.phi ();
750 if (virtual_operand_p (gimple_phi_result (phi)))
751 continue;
753 def = gimple_phi_result (phi);
754 mark_all_vars_used (&def);
756 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_ALL_USES)
758 tree arg = USE_FROM_PTR (arg_p);
759 int index = PHI_ARG_INDEX_FROM_USE (arg_p);
760 tree block =
761 LOCATION_BLOCK (gimple_phi_arg_location (phi, index));
762 if (block != NULL)
763 TREE_USED (block) = true;
764 mark_all_vars_used (&arg);
768 FOR_EACH_EDGE (e, ei, bb->succs)
769 if (LOCATION_BLOCK (e->goto_locus) != NULL)
770 TREE_USED (LOCATION_BLOCK (e->goto_locus)) = true;
773 /* We do a two-pass approach about the out-of-scope clobbers. We want
774 to remove them if they are the only references to a local variable,
775 but we want to retain them when there's any other. So the first pass
776 ignores them, and the second pass (if there were any) tries to remove
777 them. */
778 if (have_local_clobbers)
779 FOR_EACH_BB_FN (bb, cfun)
781 gimple_stmt_iterator gsi;
783 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
785 gimple *stmt = gsi_stmt (gsi);
786 tree b = gimple_block (stmt);
788 if (gimple_clobber_p (stmt))
790 tree lhs = gimple_assign_lhs (stmt);
791 tree base = get_base_address (lhs);
792 /* Remove clobbers referencing unused vars, or clobbers
793 with MEM_REF lhs referencing uninitialized pointers. */
794 if ((VAR_P (base) && !is_used_p (base))
795 || (TREE_CODE (lhs) == MEM_REF
796 && TREE_CODE (TREE_OPERAND (lhs, 0)) == SSA_NAME
797 && SSA_NAME_IS_DEFAULT_DEF (TREE_OPERAND (lhs, 0))
798 && (TREE_CODE (SSA_NAME_VAR (TREE_OPERAND (lhs, 0)))
799 != PARM_DECL)))
801 unlink_stmt_vdef (stmt);
802 gsi_remove (&gsi, true);
803 release_defs (stmt);
804 continue;
806 if (b)
807 TREE_USED (b) = true;
809 gsi_next (&gsi);
813 if (cfun->has_simduid_loops)
815 struct loop *loop;
816 FOR_EACH_LOOP (loop, 0)
817 if (loop->simduid && !is_used_p (loop->simduid))
818 loop->simduid = NULL_TREE;
821 cfun->has_local_explicit_reg_vars = false;
823 /* Remove unmarked local and global vars from local_decls. */
824 num = vec_safe_length (cfun->local_decls);
825 for (srcidx = 0, dstidx = 0; srcidx < num; srcidx++)
827 var = (*cfun->local_decls)[srcidx];
828 if (VAR_P (var))
830 if (!is_used_p (var))
832 tree def;
833 if (cfun->nonlocal_goto_save_area
834 && TREE_OPERAND (cfun->nonlocal_goto_save_area, 0) == var)
835 cfun->nonlocal_goto_save_area = NULL;
836 /* Release any default def associated with var. */
837 if ((def = ssa_default_def (cfun, var)) != NULL_TREE)
839 set_ssa_default_def (cfun, var, NULL_TREE);
840 release_ssa_name (def);
842 continue;
845 if (VAR_P (var) && DECL_HARD_REGISTER (var) && !is_global_var (var))
846 cfun->has_local_explicit_reg_vars = true;
848 if (srcidx != dstidx)
849 (*cfun->local_decls)[dstidx] = var;
850 dstidx++;
852 if (dstidx != num)
854 statistics_counter_event (cfun, "unused VAR_DECLs removed", num - dstidx);
855 cfun->local_decls->truncate (dstidx);
858 remove_unused_scope_block_p (DECL_INITIAL (current_function_decl),
859 polymorphic_ctor_dtor_p (current_function_decl,
860 true) != NULL_TREE);
861 clear_unused_block_pointer ();
863 BITMAP_FREE (usedvars);
865 if (dump_file && (dump_flags & TDF_DETAILS))
867 fprintf (dump_file, "Scope blocks after cleanups:\n");
868 dump_scope_blocks (dump_file, dump_flags);
871 timevar_pop (TV_REMOVE_UNUSED);
874 /* Allocate and return a new live range information object base on MAP. */
876 static tree_live_info_p
877 new_tree_live_info (var_map map)
879 tree_live_info_p live;
880 basic_block bb;
882 live = XNEW (struct tree_live_info_d);
883 live->map = map;
884 live->num_blocks = last_basic_block_for_fn (cfun);
886 bitmap_obstack_initialize (&live->livein_obstack);
887 bitmap_obstack_initialize (&live->liveout_obstack);
888 live->livein = XNEWVEC (bitmap_head, last_basic_block_for_fn (cfun));
889 FOR_EACH_BB_FN (bb, cfun)
890 bitmap_initialize (&live->livein[bb->index], &live->livein_obstack);
892 live->liveout = XNEWVEC (bitmap_head, last_basic_block_for_fn (cfun));
893 FOR_EACH_BB_FN (bb, cfun)
894 bitmap_initialize (&live->liveout[bb->index], &live->liveout_obstack);
896 live->work_stack = XNEWVEC (int, last_basic_block_for_fn (cfun));
897 live->stack_top = live->work_stack;
899 live->global = BITMAP_ALLOC (NULL);
900 return live;
904 /* Free storage for live range info object LIVE. */
906 void
907 delete_tree_live_info (tree_live_info_p live)
909 if (live->livein)
911 bitmap_obstack_release (&live->livein_obstack);
912 free (live->livein);
914 if (live->liveout)
916 bitmap_obstack_release (&live->liveout_obstack);
917 free (live->liveout);
919 BITMAP_FREE (live->global);
920 free (live->work_stack);
921 free (live);
925 /* Visit basic block BB and propagate any required live on entry bits from
926 LIVE into the predecessors. VISITED is the bitmap of visited blocks.
927 TMP is a temporary work bitmap which is passed in to avoid reallocating
928 it each time. */
930 static void
931 loe_visit_block (tree_live_info_p live, basic_block bb, sbitmap visited)
933 edge e;
934 bool change;
935 edge_iterator ei;
936 basic_block pred_bb;
937 bitmap loe;
939 gcc_checking_assert (!bitmap_bit_p (visited, bb->index));
940 bitmap_set_bit (visited, bb->index);
942 loe = live_on_entry (live, bb);
944 FOR_EACH_EDGE (e, ei, bb->preds)
946 pred_bb = e->src;
947 if (pred_bb == ENTRY_BLOCK_PTR_FOR_FN (cfun))
948 continue;
949 /* Variables live-on-entry from BB that aren't defined in the
950 predecessor block. This should be the live on entry vars to pred.
951 Note that liveout is the DEFs in a block while live on entry is
952 being calculated.
953 Add these bits to live-on-entry for the pred. if there are any
954 changes, and pred_bb has been visited already, add it to the
955 revisit stack. */
956 change = bitmap_ior_and_compl_into (live_on_entry (live, pred_bb),
957 loe, &live->liveout[pred_bb->index]);
958 if (change
959 && bitmap_bit_p (visited, pred_bb->index))
961 bitmap_clear_bit (visited, pred_bb->index);
962 *(live->stack_top)++ = pred_bb->index;
968 /* Using LIVE, fill in all the live-on-entry blocks between the defs and uses
969 of all the variables. */
971 static void
972 live_worklist (tree_live_info_p live)
974 unsigned b;
975 basic_block bb;
976 auto_sbitmap visited (last_basic_block_for_fn (cfun) + 1);
978 bitmap_clear (visited);
980 /* Visit all the blocks in reverse order and propagate live on entry values
981 into the predecessors blocks. */
982 FOR_EACH_BB_REVERSE_FN (bb, cfun)
983 loe_visit_block (live, bb, visited);
985 /* Process any blocks which require further iteration. */
986 while (live->stack_top != live->work_stack)
988 b = *--(live->stack_top);
989 loe_visit_block (live, BASIC_BLOCK_FOR_FN (cfun, b), visited);
994 /* Calculate the initial live on entry vector for SSA_NAME using immediate_use
995 links. Set the live on entry fields in LIVE. Def's are marked temporarily
996 in the liveout vector. */
998 static void
999 set_var_live_on_entry (tree ssa_name, tree_live_info_p live)
1001 int p;
1002 gimple *stmt;
1003 use_operand_p use;
1004 basic_block def_bb = NULL;
1005 imm_use_iterator imm_iter;
1006 bool global = false;
1008 p = var_to_partition (live->map, ssa_name);
1009 if (p == NO_PARTITION)
1010 return;
1012 stmt = SSA_NAME_DEF_STMT (ssa_name);
1013 if (stmt)
1015 def_bb = gimple_bb (stmt);
1016 /* Mark defs in liveout bitmap temporarily. */
1017 if (def_bb)
1018 bitmap_set_bit (&live->liveout[def_bb->index], p);
1020 else
1021 def_bb = ENTRY_BLOCK_PTR_FOR_FN (cfun);
1023 /* An undefined local variable does not need to be very alive. */
1024 if (ssa_undefined_value_p (ssa_name, false))
1025 return;
1027 /* Visit each use of SSA_NAME and if it isn't in the same block as the def,
1028 add it to the list of live on entry blocks. */
1029 FOR_EACH_IMM_USE_FAST (use, imm_iter, ssa_name)
1031 gimple *use_stmt = USE_STMT (use);
1032 basic_block add_block = NULL;
1034 if (gimple_code (use_stmt) == GIMPLE_PHI)
1036 /* Uses in PHI's are considered to be live at exit of the SRC block
1037 as this is where a copy would be inserted. Check to see if it is
1038 defined in that block, or whether its live on entry. */
1039 int index = PHI_ARG_INDEX_FROM_USE (use);
1040 edge e = gimple_phi_arg_edge (as_a <gphi *> (use_stmt), index);
1041 if (e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun))
1043 if (e->src != def_bb)
1044 add_block = e->src;
1047 else if (is_gimple_debug (use_stmt))
1048 continue;
1049 else
1051 /* If its not defined in this block, its live on entry. */
1052 basic_block use_bb = gimple_bb (use_stmt);
1053 if (use_bb != def_bb)
1054 add_block = use_bb;
1057 /* If there was a live on entry use, set the bit. */
1058 if (add_block)
1060 global = true;
1061 bitmap_set_bit (&live->livein[add_block->index], p);
1065 /* If SSA_NAME is live on entry to at least one block, fill in all the live
1066 on entry blocks between the def and all the uses. */
1067 if (global)
1068 bitmap_set_bit (live->global, p);
1072 /* Calculate the live on exit vectors based on the entry info in LIVEINFO. */
1074 static void
1075 calculate_live_on_exit (tree_live_info_p liveinfo)
1077 basic_block bb;
1078 edge e;
1079 edge_iterator ei;
1081 /* live on entry calculations used liveout vectors for defs, clear them. */
1082 FOR_EACH_BB_FN (bb, cfun)
1083 bitmap_clear (&liveinfo->liveout[bb->index]);
1085 /* Set all the live-on-exit bits for uses in PHIs. */
1086 FOR_EACH_BB_FN (bb, cfun)
1088 gphi_iterator gsi;
1089 size_t i;
1091 /* Mark the PHI arguments which are live on exit to the pred block. */
1092 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1094 gphi *phi = gsi.phi ();
1095 for (i = 0; i < gimple_phi_num_args (phi); i++)
1097 tree t = PHI_ARG_DEF (phi, i);
1098 int p;
1100 if (TREE_CODE (t) != SSA_NAME)
1101 continue;
1103 p = var_to_partition (liveinfo->map, t);
1104 if (p == NO_PARTITION)
1105 continue;
1106 e = gimple_phi_arg_edge (phi, i);
1107 if (e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun))
1108 bitmap_set_bit (&liveinfo->liveout[e->src->index], p);
1112 /* Add each successors live on entry to this bock live on exit. */
1113 FOR_EACH_EDGE (e, ei, bb->succs)
1114 if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun))
1115 bitmap_ior_into (&liveinfo->liveout[bb->index],
1116 live_on_entry (liveinfo, e->dest));
1121 /* Given partition map MAP, calculate all the live on entry bitmaps for
1122 each partition. Return a new live info object. */
1124 tree_live_info_p
1125 calculate_live_ranges (var_map map, bool want_livein)
1127 tree var;
1128 unsigned i;
1129 tree_live_info_p live;
1131 live = new_tree_live_info (map);
1132 for (i = 0; i < num_var_partitions (map); i++)
1134 var = partition_to_var (map, i);
1135 if (var != NULL_TREE)
1136 set_var_live_on_entry (var, live);
1139 live_worklist (live);
1141 if (flag_checking)
1142 verify_live_on_entry (live);
1144 calculate_live_on_exit (live);
1146 if (!want_livein)
1148 bitmap_obstack_release (&live->livein_obstack);
1149 free (live->livein);
1150 live->livein = NULL;
1153 return live;
1157 /* Output partition map MAP to file F. */
1159 void
1160 dump_var_map (FILE *f, var_map map)
1162 int t;
1163 unsigned x, y;
1164 int p;
1166 fprintf (f, "\nPartition map \n\n");
1168 for (x = 0; x < map->num_partitions; x++)
1170 if (map->view_to_partition != NULL)
1171 p = map->view_to_partition[x];
1172 else
1173 p = x;
1175 if (ssa_name (p) == NULL_TREE
1176 || virtual_operand_p (ssa_name (p)))
1177 continue;
1179 t = 0;
1180 for (y = 1; y < num_ssa_names; y++)
1182 p = partition_find (map->var_partition, y);
1183 if (map->partition_to_view)
1184 p = map->partition_to_view[p];
1185 if (p == (int)x)
1187 if (t++ == 0)
1189 fprintf (f, "Partition %d (", x);
1190 print_generic_expr (f, partition_to_var (map, p), TDF_SLIM);
1191 fprintf (f, " - ");
1193 fprintf (f, "%d ", y);
1196 if (t != 0)
1197 fprintf (f, ")\n");
1199 fprintf (f, "\n");
1203 /* Generic dump for the above. */
1205 DEBUG_FUNCTION void
1206 debug (_var_map &ref)
1208 dump_var_map (stderr, &ref);
1211 DEBUG_FUNCTION void
1212 debug (_var_map *ptr)
1214 if (ptr)
1215 debug (*ptr);
1216 else
1217 fprintf (stderr, "<nil>\n");
1221 /* Output live range info LIVE to file F, controlled by FLAG. */
1223 void
1224 dump_live_info (FILE *f, tree_live_info_p live, int flag)
1226 basic_block bb;
1227 unsigned i;
1228 var_map map = live->map;
1229 bitmap_iterator bi;
1231 if ((flag & LIVEDUMP_ENTRY) && live->livein)
1233 FOR_EACH_BB_FN (bb, cfun)
1235 fprintf (f, "\nLive on entry to BB%d : ", bb->index);
1236 EXECUTE_IF_SET_IN_BITMAP (&live->livein[bb->index], 0, i, bi)
1238 print_generic_expr (f, partition_to_var (map, i), TDF_SLIM);
1239 fprintf (f, " ");
1241 fprintf (f, "\n");
1245 if ((flag & LIVEDUMP_EXIT) && live->liveout)
1247 FOR_EACH_BB_FN (bb, cfun)
1249 fprintf (f, "\nLive on exit from BB%d : ", bb->index);
1250 EXECUTE_IF_SET_IN_BITMAP (&live->liveout[bb->index], 0, i, bi)
1252 print_generic_expr (f, partition_to_var (map, i), TDF_SLIM);
1253 fprintf (f, " ");
1255 fprintf (f, "\n");
1261 /* Generic dump for the above. */
1263 DEBUG_FUNCTION void
1264 debug (tree_live_info_d &ref)
1266 dump_live_info (stderr, &ref, 0);
1269 DEBUG_FUNCTION void
1270 debug (tree_live_info_d *ptr)
1272 if (ptr)
1273 debug (*ptr);
1274 else
1275 fprintf (stderr, "<nil>\n");
1279 /* Verify that the info in LIVE matches the current cfg. */
1281 static void
1282 verify_live_on_entry (tree_live_info_p live)
1284 unsigned i;
1285 tree var;
1286 gimple *stmt;
1287 basic_block bb;
1288 edge e;
1289 int num;
1290 edge_iterator ei;
1291 var_map map = live->map;
1293 /* Check for live on entry partitions and report those with a DEF in
1294 the program. This will typically mean an optimization has done
1295 something wrong. */
1296 bb = ENTRY_BLOCK_PTR_FOR_FN (cfun);
1297 num = 0;
1298 FOR_EACH_EDGE (e, ei, bb->succs)
1300 int entry_block = e->dest->index;
1301 if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
1302 continue;
1303 for (i = 0; i < (unsigned)num_var_partitions (map); i++)
1305 basic_block tmp;
1306 tree d = NULL_TREE;
1307 bitmap loe;
1308 var = partition_to_var (map, i);
1309 stmt = SSA_NAME_DEF_STMT (var);
1310 tmp = gimple_bb (stmt);
1311 if (SSA_NAME_VAR (var))
1312 d = ssa_default_def (cfun, SSA_NAME_VAR (var));
1314 loe = live_on_entry (live, e->dest);
1315 if (loe && bitmap_bit_p (loe, i))
1317 if (!gimple_nop_p (stmt))
1319 num++;
1320 print_generic_expr (stderr, var, TDF_SLIM);
1321 fprintf (stderr, " is defined ");
1322 if (tmp)
1323 fprintf (stderr, " in BB%d, ", tmp->index);
1324 fprintf (stderr, "by:\n");
1325 print_gimple_stmt (stderr, stmt, 0, TDF_SLIM);
1326 fprintf (stderr, "\nIt is also live-on-entry to entry BB %d",
1327 entry_block);
1328 fprintf (stderr, " So it appears to have multiple defs.\n");
1330 else
1332 if (d != var)
1334 num++;
1335 print_generic_expr (stderr, var, TDF_SLIM);
1336 fprintf (stderr, " is live-on-entry to BB%d ",
1337 entry_block);
1338 if (d)
1340 fprintf (stderr, " but is not the default def of ");
1341 print_generic_expr (stderr, d, TDF_SLIM);
1342 fprintf (stderr, "\n");
1344 else
1345 fprintf (stderr, " and there is no default def.\n");
1349 else
1350 if (d == var)
1352 /* An undefined local variable does not need to be very
1353 alive. */
1354 if (ssa_undefined_value_p (var, false))
1355 continue;
1357 /* The only way this var shouldn't be marked live on entry is
1358 if it occurs in a PHI argument of the block. */
1359 size_t z;
1360 bool ok = false;
1361 gphi_iterator gsi;
1362 for (gsi = gsi_start_phis (e->dest);
1363 !gsi_end_p (gsi) && !ok;
1364 gsi_next (&gsi))
1366 gphi *phi = gsi.phi ();
1367 for (z = 0; z < gimple_phi_num_args (phi); z++)
1368 if (var == gimple_phi_arg_def (phi, z))
1370 ok = true;
1371 break;
1374 if (ok)
1375 continue;
1376 /* Expand adds unused default defs for PARM_DECLs and
1377 RESULT_DECLs. They're ok. */
1378 if (has_zero_uses (var)
1379 && SSA_NAME_VAR (var)
1380 && !VAR_P (SSA_NAME_VAR (var)))
1381 continue;
1382 num++;
1383 print_generic_expr (stderr, var, TDF_SLIM);
1384 fprintf (stderr, " is not marked live-on-entry to entry BB%d ",
1385 entry_block);
1386 fprintf (stderr, "but it is a default def so it should be.\n");
1390 gcc_assert (num <= 0);