1 /* Liveness for SSA trees.
2 Copyright (C) 2003-2016 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)
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/>. */
23 #include "coretypes.h"
31 #include "gimple-pretty-print.h"
32 #include "diagnostic-core.h"
33 #include "gimple-iterator.h"
36 #include "tree-ssa-live.h"
39 #include "ipa-utils.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. */
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. */
75 init_var_map (int size)
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;
92 /* Free memory associated with MAP. */
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);
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)
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);
130 p3 = partition_union (map->var_partition, p1, p2);
132 if (map->partition_to_view)
133 p3 = map->partition_to_view[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
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
162 partition_view_init (var_map map)
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;
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. */
205 partition_view_fini (var_map map, bitmap selected)
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. */
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));
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;
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. */
241 partition_view_normal (var_map map)
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
257 partition_view_bitmap (var_map map, bitmap only)
260 bitmap new_partitions = BITMAP_ALLOC (NULL);
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. */
283 set_is_used (tree var)
285 return bitmap_set_bit (usedvars, DECL_UID (var));
288 /* Return true if VAR is marked as used. */
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. */
301 mark_all_vars_used_1 (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
304 enum tree_code_class c = TREE_CODE_CLASS (TREE_CODE (t));
307 if (TREE_CODE (t) == SSA_NAME)
310 t = SSA_NAME_VAR (t);
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));
330 /* Only need to mark VAR_DECLS; parameters and return results are not
331 eliminated as unused. */
332 if (TREE_CODE (t) == VAR_DECL)
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. */
349 if (IS_TYPE_OR_DECL_P (t))
355 /* Mark the scope block SCOPE and its subblocks unused when they can be
356 possibly eliminated if dead. */
359 mark_scope_block_unused (tree scope)
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. */
383 remove_unused_scope_block_p (tree scope, bool in_ctor_dtor_block)
386 bool unused = !TREE_USED (scope);
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;
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;
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)
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 (TREE_CODE (*t) == VAR_DECL && DECL_HAS_VALUE_EXPR_P (*t))
431 /* Remove everything we don't generate debug info for. */
432 else if (DECL_IGNORED_P (*t))
434 *t = DECL_CHAIN (*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))
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. */
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
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)
481 *t = DECL_CHAIN (*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);
506 *t = BLOCK_CHAIN (*t);
510 t = &BLOCK_CHAIN (*t);
517 /* Outer scope is always used. */
518 else if (!BLOCK_SUPERCONTEXT (scope)
519 || TREE_CODE (BLOCK_SUPERCONTEXT (scope)) == FUNCTION_DECL)
521 /* Innermost blocks with no live variables nor statements can be always
523 else if (!nsubblocks)
525 /* When not generating debug info we can eliminate info on unused
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))
537 && TREE_CODE (ao) == BLOCK
538 && BLOCK_ABSTRACT_ORIGIN (ao) != ao)
539 ao = BLOCK_ABSTRACT_ORIGIN (ao);
541 && TREE_CODE (ao) == FUNCTION_DECL
542 && DECL_DECLARED_INLINE_P (ao)
543 && lookup_attribute ("artificial", DECL_ATTRIBUTES (ao)))
547 else if (BLOCK_VARS (scope) || BLOCK_NUM_NONLOCALIZED_VARS (scope))
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
553 else if (inlined_function_outer_scope_p (scope))
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;
565 /* Mark all VAR_DECLS under *EXPR_P as used, so that they won't be
566 eliminated during the tree->rtl conversion process. */
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. */
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);
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. */
589 clear_unused_block_pointer (void)
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))
599 gimple *stmt = gsi_stmt (gsi);
601 if (!is_gimple_debug (stmt) && !gimple_clobber_p (stmt))
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,
612 /* Dump scope blocks starting at SCOPE to FILE. INDENT is the
613 indentation level and FLAGS is as in print_generic_expr. */
616 dump_scope_block (FILE *file, int indent, tree scope, int flags)
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);
634 fprintf (file, " Originating from :");
636 print_generic_decl (file, origin, flags);
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),
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. */
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. */
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. */
684 debug_scope_blocks (int flags)
686 dump_scope_blocks (stderr, flags);
689 /* Remove local variables that are not referenced in the IL. */
692 remove_unused_locals (void)
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
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;
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))
728 if (gimple_clobber_p (stmt))
730 have_local_clobbers = true;
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);
748 gphi *phi = gpi.phi ();
750 if (virtual_operand_p (gimple_phi_result (phi)))
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);
761 LOCATION_BLOCK (gimple_phi_arg_location (phi, index));
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
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 ((TREE_CODE (base) == VAR_DECL && !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)))
801 unlink_stmt_vdef (stmt);
802 gsi_remove (&gsi, true);
807 TREE_USED (b) = true;
813 if (cfun->has_simduid_loops)
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 (TREE_CODE (var) == VAR_DECL)
830 if (!is_used_p (var))
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);
845 if (TREE_CODE (var) == VAR_DECL
846 && DECL_HARD_REGISTER (var)
847 && !is_global_var (var))
848 cfun->has_local_explicit_reg_vars = true;
850 if (srcidx != dstidx)
851 (*cfun->local_decls)[dstidx] = var;
856 statistics_counter_event (cfun, "unused VAR_DECLs removed", num - dstidx);
857 cfun->local_decls->truncate (dstidx);
860 remove_unused_scope_block_p (DECL_INITIAL (current_function_decl),
861 polymorphic_ctor_dtor_p (current_function_decl,
863 clear_unused_block_pointer ();
865 BITMAP_FREE (usedvars);
867 if (dump_file && (dump_flags & TDF_DETAILS))
869 fprintf (dump_file, "Scope blocks after cleanups:\n");
870 dump_scope_blocks (dump_file, dump_flags);
873 timevar_pop (TV_REMOVE_UNUSED);
876 /* Allocate and return a new live range information object base on MAP. */
878 static tree_live_info_p
879 new_tree_live_info (var_map map)
881 tree_live_info_p live;
884 live = XNEW (struct tree_live_info_d);
886 live->num_blocks = last_basic_block_for_fn (cfun);
888 bitmap_obstack_initialize (&live->livein_obstack);
889 bitmap_obstack_initialize (&live->liveout_obstack);
890 live->livein = XNEWVEC (bitmap_head, last_basic_block_for_fn (cfun));
891 FOR_EACH_BB_FN (bb, cfun)
892 bitmap_initialize (&live->livein[bb->index], &live->livein_obstack);
894 live->liveout = XNEWVEC (bitmap_head, last_basic_block_for_fn (cfun));
895 FOR_EACH_BB_FN (bb, cfun)
896 bitmap_initialize (&live->liveout[bb->index], &live->liveout_obstack);
898 live->work_stack = XNEWVEC (int, last_basic_block_for_fn (cfun));
899 live->stack_top = live->work_stack;
901 live->global = BITMAP_ALLOC (NULL);
906 /* Free storage for live range info object LIVE. */
909 delete_tree_live_info (tree_live_info_p live)
913 bitmap_obstack_release (&live->livein_obstack);
918 bitmap_obstack_release (&live->liveout_obstack);
919 free (live->liveout);
921 BITMAP_FREE (live->global);
922 free (live->work_stack);
927 /* Visit basic block BB and propagate any required live on entry bits from
928 LIVE into the predecessors. VISITED is the bitmap of visited blocks.
929 TMP is a temporary work bitmap which is passed in to avoid reallocating
933 loe_visit_block (tree_live_info_p live, basic_block bb, sbitmap visited)
941 gcc_checking_assert (!bitmap_bit_p (visited, bb->index));
942 bitmap_set_bit (visited, bb->index);
944 loe = live_on_entry (live, bb);
946 FOR_EACH_EDGE (e, ei, bb->preds)
949 if (pred_bb == ENTRY_BLOCK_PTR_FOR_FN (cfun))
951 /* Variables live-on-entry from BB that aren't defined in the
952 predecessor block. This should be the live on entry vars to pred.
953 Note that liveout is the DEFs in a block while live on entry is
955 Add these bits to live-on-entry for the pred. if there are any
956 changes, and pred_bb has been visited already, add it to the
958 change = bitmap_ior_and_compl_into (live_on_entry (live, pred_bb),
959 loe, &live->liveout[pred_bb->index]);
961 && bitmap_bit_p (visited, pred_bb->index))
963 bitmap_clear_bit (visited, pred_bb->index);
964 *(live->stack_top)++ = pred_bb->index;
970 /* Using LIVE, fill in all the live-on-entry blocks between the defs and uses
971 of all the variables. */
974 live_worklist (tree_live_info_p live)
978 sbitmap visited = sbitmap_alloc (last_basic_block_for_fn (cfun) + 1);
980 bitmap_clear (visited);
982 /* Visit all the blocks in reverse order and propagate live on entry values
983 into the predecessors blocks. */
984 FOR_EACH_BB_REVERSE_FN (bb, cfun)
985 loe_visit_block (live, bb, visited);
987 /* Process any blocks which require further iteration. */
988 while (live->stack_top != live->work_stack)
990 b = *--(live->stack_top);
991 loe_visit_block (live, BASIC_BLOCK_FOR_FN (cfun, b), visited);
994 sbitmap_free (visited);
998 /* Calculate the initial live on entry vector for SSA_NAME using immediate_use
999 links. Set the live on entry fields in LIVE. Def's are marked temporarily
1000 in the liveout vector. */
1003 set_var_live_on_entry (tree ssa_name, tree_live_info_p live)
1008 basic_block def_bb = NULL;
1009 imm_use_iterator imm_iter;
1010 bool global = false;
1012 p = var_to_partition (live->map, ssa_name);
1013 if (p == NO_PARTITION)
1016 stmt = SSA_NAME_DEF_STMT (ssa_name);
1019 def_bb = gimple_bb (stmt);
1020 /* Mark defs in liveout bitmap temporarily. */
1022 bitmap_set_bit (&live->liveout[def_bb->index], p);
1025 def_bb = ENTRY_BLOCK_PTR_FOR_FN (cfun);
1027 /* An undefined local variable does not need to be very alive. */
1028 if (ssa_undefined_value_p (ssa_name, false))
1031 /* Visit each use of SSA_NAME and if it isn't in the same block as the def,
1032 add it to the list of live on entry blocks. */
1033 FOR_EACH_IMM_USE_FAST (use, imm_iter, ssa_name)
1035 gimple *use_stmt = USE_STMT (use);
1036 basic_block add_block = NULL;
1038 if (gimple_code (use_stmt) == GIMPLE_PHI)
1040 /* Uses in PHI's are considered to be live at exit of the SRC block
1041 as this is where a copy would be inserted. Check to see if it is
1042 defined in that block, or whether its live on entry. */
1043 int index = PHI_ARG_INDEX_FROM_USE (use);
1044 edge e = gimple_phi_arg_edge (as_a <gphi *> (use_stmt), index);
1045 if (e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun))
1047 if (e->src != def_bb)
1051 else if (is_gimple_debug (use_stmt))
1055 /* If its not defined in this block, its live on entry. */
1056 basic_block use_bb = gimple_bb (use_stmt);
1057 if (use_bb != def_bb)
1061 /* If there was a live on entry use, set the bit. */
1065 bitmap_set_bit (&live->livein[add_block->index], p);
1069 /* If SSA_NAME is live on entry to at least one block, fill in all the live
1070 on entry blocks between the def and all the uses. */
1072 bitmap_set_bit (live->global, p);
1076 /* Calculate the live on exit vectors based on the entry info in LIVEINFO. */
1079 calculate_live_on_exit (tree_live_info_p liveinfo)
1085 /* live on entry calculations used liveout vectors for defs, clear them. */
1086 FOR_EACH_BB_FN (bb, cfun)
1087 bitmap_clear (&liveinfo->liveout[bb->index]);
1089 /* Set all the live-on-exit bits for uses in PHIs. */
1090 FOR_EACH_BB_FN (bb, cfun)
1095 /* Mark the PHI arguments which are live on exit to the pred block. */
1096 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1098 gphi *phi = gsi.phi ();
1099 for (i = 0; i < gimple_phi_num_args (phi); i++)
1101 tree t = PHI_ARG_DEF (phi, i);
1104 if (TREE_CODE (t) != SSA_NAME)
1107 p = var_to_partition (liveinfo->map, t);
1108 if (p == NO_PARTITION)
1110 e = gimple_phi_arg_edge (phi, i);
1111 if (e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun))
1112 bitmap_set_bit (&liveinfo->liveout[e->src->index], p);
1116 /* Add each successors live on entry to this bock live on exit. */
1117 FOR_EACH_EDGE (e, ei, bb->succs)
1118 if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun))
1119 bitmap_ior_into (&liveinfo->liveout[bb->index],
1120 live_on_entry (liveinfo, e->dest));
1125 /* Given partition map MAP, calculate all the live on entry bitmaps for
1126 each partition. Return a new live info object. */
1129 calculate_live_ranges (var_map map, bool want_livein)
1133 tree_live_info_p live;
1135 live = new_tree_live_info (map);
1136 for (i = 0; i < num_var_partitions (map); i++)
1138 var = partition_to_var (map, i);
1139 if (var != NULL_TREE)
1140 set_var_live_on_entry (var, live);
1143 live_worklist (live);
1146 verify_live_on_entry (live);
1148 calculate_live_on_exit (live);
1152 bitmap_obstack_release (&live->livein_obstack);
1153 free (live->livein);
1154 live->livein = NULL;
1161 /* Output partition map MAP to file F. */
1164 dump_var_map (FILE *f, var_map map)
1170 fprintf (f, "\nPartition map \n\n");
1172 for (x = 0; x < map->num_partitions; x++)
1174 if (map->view_to_partition != NULL)
1175 p = map->view_to_partition[x];
1179 if (ssa_name (p) == NULL_TREE
1180 || virtual_operand_p (ssa_name (p)))
1184 for (y = 1; y < num_ssa_names; y++)
1186 p = partition_find (map->var_partition, y);
1187 if (map->partition_to_view)
1188 p = map->partition_to_view[p];
1193 fprintf (f, "Partition %d (", x);
1194 print_generic_expr (f, partition_to_var (map, p), TDF_SLIM);
1197 fprintf (f, "%d ", y);
1207 /* Generic dump for the above. */
1210 debug (_var_map &ref)
1212 dump_var_map (stderr, &ref);
1216 debug (_var_map *ptr)
1221 fprintf (stderr, "<nil>\n");
1225 /* Output live range info LIVE to file F, controlled by FLAG. */
1228 dump_live_info (FILE *f, tree_live_info_p live, int flag)
1232 var_map map = live->map;
1235 if ((flag & LIVEDUMP_ENTRY) && live->livein)
1237 FOR_EACH_BB_FN (bb, cfun)
1239 fprintf (f, "\nLive on entry to BB%d : ", bb->index);
1240 EXECUTE_IF_SET_IN_BITMAP (&live->livein[bb->index], 0, i, bi)
1242 print_generic_expr (f, partition_to_var (map, i), TDF_SLIM);
1249 if ((flag & LIVEDUMP_EXIT) && live->liveout)
1251 FOR_EACH_BB_FN (bb, cfun)
1253 fprintf (f, "\nLive on exit from BB%d : ", bb->index);
1254 EXECUTE_IF_SET_IN_BITMAP (&live->liveout[bb->index], 0, i, bi)
1256 print_generic_expr (f, partition_to_var (map, i), TDF_SLIM);
1265 /* Generic dump for the above. */
1268 debug (tree_live_info_d &ref)
1270 dump_live_info (stderr, &ref, 0);
1274 debug (tree_live_info_d *ptr)
1279 fprintf (stderr, "<nil>\n");
1283 /* Verify that SSA_VAR is a non-virtual SSA_NAME. */
1286 register_ssa_partition_check (tree ssa_var)
1288 gcc_assert (TREE_CODE (ssa_var) == SSA_NAME);
1289 if (virtual_operand_p (ssa_var))
1291 fprintf (stderr, "Illegally registering a virtual SSA name :");
1292 print_generic_expr (stderr, ssa_var, TDF_SLIM);
1293 fprintf (stderr, " in the SSA->Normal phase.\n");
1294 internal_error ("SSA corruption");
1299 /* Verify that the info in LIVE matches the current cfg. */
1302 verify_live_on_entry (tree_live_info_p live)
1311 var_map map = live->map;
1313 /* Check for live on entry partitions and report those with a DEF in
1314 the program. This will typically mean an optimization has done
1316 bb = ENTRY_BLOCK_PTR_FOR_FN (cfun);
1318 FOR_EACH_EDGE (e, ei, bb->succs)
1320 int entry_block = e->dest->index;
1321 if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
1323 for (i = 0; i < (unsigned)num_var_partitions (map); i++)
1328 var = partition_to_var (map, i);
1329 stmt = SSA_NAME_DEF_STMT (var);
1330 tmp = gimple_bb (stmt);
1331 if (SSA_NAME_VAR (var))
1332 d = ssa_default_def (cfun, SSA_NAME_VAR (var));
1334 loe = live_on_entry (live, e->dest);
1335 if (loe && bitmap_bit_p (loe, i))
1337 if (!gimple_nop_p (stmt))
1340 print_generic_expr (stderr, var, TDF_SLIM);
1341 fprintf (stderr, " is defined ");
1343 fprintf (stderr, " in BB%d, ", tmp->index);
1344 fprintf (stderr, "by:\n");
1345 print_gimple_stmt (stderr, stmt, 0, TDF_SLIM);
1346 fprintf (stderr, "\nIt is also live-on-entry to entry BB %d",
1348 fprintf (stderr, " So it appears to have multiple defs.\n");
1355 print_generic_expr (stderr, var, TDF_SLIM);
1356 fprintf (stderr, " is live-on-entry to BB%d ",
1360 fprintf (stderr, " but is not the default def of ");
1361 print_generic_expr (stderr, d, TDF_SLIM);
1362 fprintf (stderr, "\n");
1365 fprintf (stderr, " and there is no default def.\n");
1372 /* An undefined local variable does not need to be very
1374 if (ssa_undefined_value_p (var, false))
1377 /* The only way this var shouldn't be marked live on entry is
1378 if it occurs in a PHI argument of the block. */
1382 for (gsi = gsi_start_phis (e->dest);
1383 !gsi_end_p (gsi) && !ok;
1386 gphi *phi = gsi.phi ();
1387 for (z = 0; z < gimple_phi_num_args (phi); z++)
1388 if (var == gimple_phi_arg_def (phi, z))
1396 /* Expand adds unused default defs for PARM_DECLs and
1397 RESULT_DECLs. They're ok. */
1398 if (has_zero_uses (var)
1399 && SSA_NAME_VAR (var)
1400 && !VAR_P (SSA_NAME_VAR (var)))
1403 print_generic_expr (stderr, var, TDF_SLIM);
1404 fprintf (stderr, " is not marked live-on-entry to entry BB%d ",
1406 fprintf (stderr, "but it is a default def so it should be.\n");
1410 gcc_assert (num <= 0);