1 /* Liveness for SSA trees.
2 Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011
3 Free Software Foundation, Inc.
4 Contributed by Andrew MacLeod <amacleod@redhat.com>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3, or (at your option)
13 GCC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
24 #include "coretypes.h"
27 #include "tree-pretty-print.h"
28 #include "gimple-pretty-print.h"
30 #include "tree-flow.h"
31 #include "tree-dump.h"
32 #include "tree-ssa-live.h"
33 #include "diagnostic-core.h"
38 #ifdef ENABLE_CHECKING
39 static void verify_live_on_entry (tree_live_info_p);
43 /* VARMAP maintains a mapping from SSA version number to real variables.
45 All SSA_NAMES are divided into partitions. Initially each ssa_name is the
46 only member of it's own partition. Coalescing will attempt to group any
47 ssa_names which occur in a copy or in a PHI node into the same partition.
49 At the end of out-of-ssa, each partition becomes a "real" variable and is
50 rewritten as a compiler variable.
52 The var_map data structure is used to manage these partitions. It allows
53 partitions to be combined, and determines which partition belongs to what
54 ssa_name or variable, and vice versa. */
57 /* This routine will initialize the basevar fields of MAP. */
60 var_map_base_init (var_map map)
67 num_part = num_var_partitions (map);
69 /* If a base table already exists, clear it, otherwise create it. */
70 if (map->partition_to_base_index != NULL)
72 free (map->partition_to_base_index);
73 VEC_truncate (tree, map->basevars, 0);
76 map->basevars = VEC_alloc (tree, heap, MAX (40, (num_part / 10)));
78 map->partition_to_base_index = (int *) xmalloc (sizeof (int) * num_part);
80 /* Build the base variable list, and point partitions at their bases. */
81 for (x = 0; x < num_part; x++)
83 var = partition_to_var (map, x);
84 if (TREE_CODE (var) == SSA_NAME)
85 var = SSA_NAME_VAR (var);
87 /* If base variable hasn't been seen, set it up. */
88 if (!ann->base_var_processed)
90 ann->base_var_processed = 1;
91 VAR_ANN_BASE_INDEX (ann) = num++;
92 VEC_safe_push (tree, heap, map->basevars, var);
94 map->partition_to_base_index[x] = VAR_ANN_BASE_INDEX (ann);
97 map->num_basevars = num;
99 /* Now clear the processed bit. */
100 for (x = 0; x < num; x++)
102 var = VEC_index (tree, map->basevars, x);
103 var_ann (var)->base_var_processed = 0;
106 #ifdef ENABLE_CHECKING
107 for (x = 0; x < num_part; x++)
110 var = SSA_NAME_VAR (partition_to_var (map, x));
111 var2 = VEC_index (tree, map->basevars, basevar_index (map, x));
112 gcc_assert (var == var2);
118 /* Remove the base table in MAP. */
121 var_map_base_fini (var_map map)
123 /* Free the basevar info if it is present. */
124 if (map->partition_to_base_index != NULL)
126 VEC_free (tree, heap, map->basevars);
127 free (map->partition_to_base_index);
128 map->partition_to_base_index = NULL;
129 map->num_basevars = 0;
132 /* Create a variable partition map of SIZE, initialize and return it. */
135 init_var_map (int size)
139 map = (var_map) xmalloc (sizeof (struct _var_map));
140 map->var_partition = partition_new (size);
142 map->partition_to_view = NULL;
143 map->view_to_partition = NULL;
144 map->num_partitions = size;
145 map->partition_size = size;
146 map->num_basevars = 0;
147 map->partition_to_base_index = NULL;
148 map->basevars = NULL;
153 /* Free memory associated with MAP. */
156 delete_var_map (var_map map)
158 var_map_base_fini (map);
159 partition_delete (map->var_partition);
160 free (map->partition_to_view);
161 free (map->view_to_partition);
166 /* This function will combine the partitions in MAP for VAR1 and VAR2. It
167 Returns the partition which represents the new partition. If the two
168 partitions cannot be combined, NO_PARTITION is returned. */
171 var_union (var_map map, tree var1, tree var2)
175 gcc_assert (TREE_CODE (var1) == SSA_NAME);
176 gcc_assert (TREE_CODE (var2) == SSA_NAME);
178 /* This is independent of partition_to_view. If partition_to_view is
179 on, then whichever one of these partitions is absorbed will never have a
180 dereference into the partition_to_view array any more. */
182 p1 = partition_find (map->var_partition, SSA_NAME_VERSION (var1));
183 p2 = partition_find (map->var_partition, SSA_NAME_VERSION (var2));
185 gcc_assert (p1 != NO_PARTITION);
186 gcc_assert (p2 != NO_PARTITION);
191 p3 = partition_union (map->var_partition, p1, p2);
193 if (map->partition_to_view)
194 p3 = map->partition_to_view[p3];
200 /* Compress the partition numbers in MAP such that they fall in the range
201 0..(num_partitions-1) instead of wherever they turned out during
202 the partitioning exercise. This removes any references to unused
203 partitions, thereby allowing bitmaps and other vectors to be much
206 This is implemented such that compaction doesn't affect partitioning.
207 Ie., once partitions are created and possibly merged, running one
208 or more different kind of compaction will not affect the partitions
209 themselves. Their index might change, but all the same variables will
210 still be members of the same partition group. This allows work on reduced
211 sets, and no loss of information when a larger set is later desired.
213 In particular, coalescing can work on partitions which have 2 or more
214 definitions, and then 'recompact' later to include all the single
215 definitions for assignment to program variables. */
218 /* Set MAP back to the initial state of having no partition view. Return a
219 bitmap which has a bit set for each partition number which is in use in the
223 partition_view_init (var_map map)
229 used = BITMAP_ALLOC (NULL);
231 /* Already in a view? Abandon the old one. */
232 if (map->partition_to_view)
234 free (map->partition_to_view);
235 map->partition_to_view = NULL;
237 if (map->view_to_partition)
239 free (map->view_to_partition);
240 map->view_to_partition = NULL;
243 /* Find out which partitions are actually referenced. */
244 for (x = 0; x < map->partition_size; x++)
246 tmp = partition_find (map->var_partition, x);
247 if (ssa_name (tmp) != NULL_TREE && is_gimple_reg (ssa_name (tmp))
248 && (!has_zero_uses (ssa_name (tmp))
249 || !SSA_NAME_IS_DEFAULT_DEF (ssa_name (tmp))))
250 bitmap_set_bit (used, tmp);
253 map->num_partitions = map->partition_size;
258 /* This routine will finalize the view data for MAP based on the partitions
259 set in SELECTED. This is either the same bitmap returned from
260 partition_view_init, or a trimmed down version if some of those partitions
261 were not desired in this view. SELECTED is freed before returning. */
264 partition_view_fini (var_map map, bitmap selected)
267 unsigned count, i, x, limit;
269 gcc_assert (selected);
271 count = bitmap_count_bits (selected);
272 limit = map->partition_size;
274 /* If its a one-to-one ratio, we don't need any view compaction. */
277 map->partition_to_view = (int *)xmalloc (limit * sizeof (int));
278 memset (map->partition_to_view, 0xff, (limit * sizeof (int)));
279 map->view_to_partition = (int *)xmalloc (count * sizeof (int));
282 /* Give each selected partition an index. */
283 EXECUTE_IF_SET_IN_BITMAP (selected, 0, x, bi)
285 map->partition_to_view[x] = i;
286 map->view_to_partition[i] = x;
289 gcc_assert (i == count);
290 map->num_partitions = i;
293 BITMAP_FREE (selected);
297 /* Create a partition view which includes all the used partitions in MAP. If
298 WANT_BASES is true, create the base variable map as well. */
301 partition_view_normal (var_map map, bool want_bases)
305 used = partition_view_init (map);
306 partition_view_fini (map, used);
309 var_map_base_init (map);
311 var_map_base_fini (map);
315 /* Create a partition view in MAP which includes just partitions which occur in
316 the bitmap ONLY. If WANT_BASES is true, create the base variable map
320 partition_view_bitmap (var_map map, bitmap only, bool want_bases)
323 bitmap new_partitions = BITMAP_ALLOC (NULL);
327 used = partition_view_init (map);
328 EXECUTE_IF_SET_IN_BITMAP (only, 0, x, bi)
330 p = partition_find (map->var_partition, x);
331 gcc_assert (bitmap_bit_p (used, p));
332 bitmap_set_bit (new_partitions, p);
334 partition_view_fini (map, new_partitions);
338 var_map_base_init (map);
340 var_map_base_fini (map);
344 static inline void mark_all_vars_used (tree *, void *data);
346 /* Helper function for mark_all_vars_used, called via walk_tree. */
349 mark_all_vars_used_1 (tree *tp, int *walk_subtrees, void *data)
352 enum tree_code_class c = TREE_CODE_CLASS (TREE_CODE (t));
355 if (TREE_CODE (t) == SSA_NAME)
356 t = SSA_NAME_VAR (t);
358 if (IS_EXPR_CODE_CLASS (c)
359 && (b = TREE_BLOCK (t)) != NULL)
360 TREE_USED (b) = true;
362 /* Ignore TMR_OFFSET and TMR_STEP for TARGET_MEM_REFS, as those
363 fields do not contain vars. */
364 if (TREE_CODE (t) == TARGET_MEM_REF)
366 mark_all_vars_used (&TMR_BASE (t), data);
367 mark_all_vars_used (&TMR_INDEX (t), data);
368 mark_all_vars_used (&TMR_INDEX2 (t), data);
373 /* Only need to mark VAR_DECLS; parameters and return results are not
374 eliminated as unused. */
375 if (TREE_CODE (t) == VAR_DECL)
377 if (data != NULL && bitmap_clear_bit ((bitmap) data, DECL_UID (t))
378 && DECL_CONTEXT (t) == current_function_decl)
379 mark_all_vars_used (&DECL_INITIAL (t), data);
382 /* remove_unused_scope_block_p requires information about labels
383 which are not DECL_IGNORED_P to tell if they might be used in the IL. */
384 if (TREE_CODE (t) == LABEL_DECL)
385 /* Although the TREE_USED values that the frontend uses would be
386 acceptable (albeit slightly over-conservative) for our purposes,
387 init_vars_expansion clears TREE_USED for LABEL_DECLs too, so we
388 must re-compute it here. */
391 if (IS_TYPE_OR_DECL_P (t))
397 /* Mark the scope block SCOPE and its subblocks unused when they can be
398 possibly eliminated if dead. */
401 mark_scope_block_unused (tree scope)
404 TREE_USED (scope) = false;
405 if (!(*debug_hooks->ignore_block) (scope))
406 TREE_USED (scope) = true;
407 for (t = BLOCK_SUBBLOCKS (scope); t ; t = BLOCK_CHAIN (t))
408 mark_scope_block_unused (t);
411 /* Look if the block is dead (by possibly eliminating its dead subblocks)
412 and return true if so.
413 Block is declared dead if:
414 1) No statements are associated with it.
415 2) Declares no live variables
416 3) All subblocks are dead
417 or there is precisely one subblocks and the block
418 has same abstract origin as outer block and declares
419 no variables, so it is pure wrapper.
420 When we are not outputting full debug info, we also eliminate dead variables
421 out of scope blocks to let them to be recycled by GGC and to save copying work
422 done by the inliner. */
425 remove_unused_scope_block_p (tree scope)
428 bool unused = !TREE_USED (scope);
431 for (t = &BLOCK_VARS (scope); *t; t = next)
433 next = &DECL_CHAIN (*t);
435 /* Debug info of nested function refers to the block of the
436 function. We might stil call it even if all statements
437 of function it was nested into was elliminated.
439 TODO: We can actually look into cgraph to see if function
440 will be output to file. */
441 if (TREE_CODE (*t) == FUNCTION_DECL)
444 /* If a decl has a value expr, we need to instantiate it
445 regardless of debug info generation, to avoid codegen
446 differences in memory overlap tests. update_equiv_regs() may
447 indirectly call validate_equiv_mem() to test whether a
448 SET_DEST overlaps with others, and if the value expr changes
449 by virtual register instantiation, we may get end up with
450 different results. */
451 else if (TREE_CODE (*t) == VAR_DECL && DECL_HAS_VALUE_EXPR_P (*t))
454 /* Remove everything we don't generate debug info for. */
455 else if (DECL_IGNORED_P (*t))
457 *t = DECL_CHAIN (*t);
461 /* When we are outputting debug info, we usually want to output
462 info about optimized-out variables in the scope blocks.
463 Exception are the scope blocks not containing any instructions
464 at all so user can't get into the scopes at first place. */
465 else if (var_ann (*t) != NULL && is_used_p (*t))
467 else if (TREE_CODE (*t) == LABEL_DECL && TREE_USED (*t))
468 /* For labels that are still used in the IL, the decision to
469 preserve them must not depend DEBUG_INFO_LEVEL, otherwise we
470 risk having different ordering in debug vs. non-debug builds
471 during inlining or versioning.
472 A label appearing here (we have already checked DECL_IGNORED_P)
473 should not be used in the IL unless it has been explicitly used
474 before, so we use TREE_USED as an approximation. */
475 /* In principle, we should do the same here as for the debug case
476 below, however, when debugging, there might be additional nested
477 levels that keep an upper level with a label live, so we have to
478 force this block to be considered used, too. */
481 /* When we are not doing full debug info, we however can keep around
482 only the used variables for cfgexpand's memory packing saving quite
485 For sake of -g3, we keep around those vars but we don't count this as
486 use of block, so innermost block with no used vars and no instructions
487 can be considered dead. We only want to keep around blocks user can
488 breakpoint into and ask about value of optimized out variables.
490 Similarly we need to keep around types at least until all
491 variables of all nested blocks are gone. We track no
492 information on whether given type is used or not, so we have
493 to keep them even when not emitting debug information,
494 otherwise we may end up remapping variables and their (local)
495 types in different orders depending on whether debug
496 information is being generated. */
498 else if (TREE_CODE (*t) == TYPE_DECL
499 || debug_info_level == DINFO_LEVEL_NORMAL
500 || debug_info_level == DINFO_LEVEL_VERBOSE)
504 *t = DECL_CHAIN (*t);
509 for (t = &BLOCK_SUBBLOCKS (scope); *t ;)
510 if (remove_unused_scope_block_p (*t))
512 if (BLOCK_SUBBLOCKS (*t))
514 tree next = BLOCK_CHAIN (*t);
515 tree supercontext = BLOCK_SUPERCONTEXT (*t);
517 *t = BLOCK_SUBBLOCKS (*t);
518 while (BLOCK_CHAIN (*t))
520 BLOCK_SUPERCONTEXT (*t) = supercontext;
521 t = &BLOCK_CHAIN (*t);
523 BLOCK_CHAIN (*t) = next;
524 BLOCK_SUPERCONTEXT (*t) = supercontext;
525 t = &BLOCK_CHAIN (*t);
529 *t = BLOCK_CHAIN (*t);
533 t = &BLOCK_CHAIN (*t);
540 /* Outer scope is always used. */
541 else if (!BLOCK_SUPERCONTEXT (scope)
542 || TREE_CODE (BLOCK_SUPERCONTEXT (scope)) == FUNCTION_DECL)
544 /* Innermost blocks with no live variables nor statements can be always
546 else if (!nsubblocks)
548 /* For terse debug info we can eliminate info on unused variables. */
549 else if (debug_info_level == DINFO_LEVEL_NONE
550 || debug_info_level == DINFO_LEVEL_TERSE)
552 /* Even for -g0/-g1 don't prune outer scopes from artificial
553 functions, otherwise diagnostics using tree_nonartificial_location
554 will not be emitted properly. */
555 if (inlined_function_outer_scope_p (scope))
560 && TREE_CODE (ao) == BLOCK
561 && BLOCK_ABSTRACT_ORIGIN (ao) != ao)
562 ao = BLOCK_ABSTRACT_ORIGIN (ao);
564 && TREE_CODE (ao) == FUNCTION_DECL
565 && DECL_DECLARED_INLINE_P (ao)
566 && lookup_attribute ("artificial", DECL_ATTRIBUTES (ao)))
570 else if (BLOCK_VARS (scope) || BLOCK_NUM_NONLOCALIZED_VARS (scope))
572 /* See if this block is important for representation of inlined function.
573 Inlined functions are always represented by block with
574 block_ultimate_origin being set to FUNCTION_DECL and DECL_SOURCE_LOCATION
576 else if (inlined_function_outer_scope_p (scope))
579 /* Verfify that only blocks with source location set
580 are entry points to the inlined functions. */
581 gcc_assert (BLOCK_SOURCE_LOCATION (scope) == UNKNOWN_LOCATION);
583 TREE_USED (scope) = !unused;
587 /* Mark all VAR_DECLS under *EXPR_P as used, so that they won't be
588 eliminated during the tree->rtl conversion process. */
591 mark_all_vars_used (tree *expr_p, void *data)
593 walk_tree (expr_p, mark_all_vars_used_1, data, NULL);
597 /* Dump scope blocks starting at SCOPE to FILE. INDENT is the
598 indentation level and FLAGS is as in print_generic_expr. */
601 dump_scope_block (FILE *file, int indent, tree scope, int flags)
606 fprintf (file, "\n%*s{ Scope block #%i%s%s",indent, "" , BLOCK_NUMBER (scope),
607 TREE_USED (scope) ? "" : " (unused)",
608 BLOCK_ABSTRACT (scope) ? " (abstract)": "");
609 if (BLOCK_SOURCE_LOCATION (scope) != UNKNOWN_LOCATION)
611 expanded_location s = expand_location (BLOCK_SOURCE_LOCATION (scope));
612 fprintf (file, " %s:%i", s.file, s.line);
614 if (BLOCK_ABSTRACT_ORIGIN (scope))
616 tree origin = block_ultimate_origin (scope);
619 fprintf (file, " Originating from :");
621 print_generic_decl (file, origin, flags);
623 fprintf (file, "#%i", BLOCK_NUMBER (origin));
626 fprintf (file, " \n");
627 for (var = BLOCK_VARS (scope); var; var = DECL_CHAIN (var))
632 used = is_used_p (var);
634 fprintf (file, "%*s", indent, "");
635 print_generic_decl (file, var, flags);
636 fprintf (file, "%s\n", used ? "" : " (unused)");
638 for (i = 0; i < BLOCK_NUM_NONLOCALIZED_VARS (scope); i++)
640 fprintf (file, "%*s",indent, "");
641 print_generic_decl (file, BLOCK_NONLOCALIZED_VAR (scope, i),
643 fprintf (file, " (nonlocalized)\n");
645 for (t = BLOCK_SUBBLOCKS (scope); t ; t = BLOCK_CHAIN (t))
646 dump_scope_block (file, indent + 2, t, flags);
647 fprintf (file, "\n%*s}\n",indent, "");
650 /* Dump the tree of lexical scopes starting at SCOPE to stderr. FLAGS
651 is as in print_generic_expr. */
654 debug_scope_block (tree scope, int flags)
656 dump_scope_block (stderr, 0, scope, flags);
660 /* Dump the tree of lexical scopes of current_function_decl to FILE.
661 FLAGS is as in print_generic_expr. */
664 dump_scope_blocks (FILE *file, int flags)
666 dump_scope_block (file, 0, DECL_INITIAL (current_function_decl), flags);
670 /* Dump the tree of lexical scopes of current_function_decl to stderr.
671 FLAGS is as in print_generic_expr. */
674 debug_scope_blocks (int flags)
676 dump_scope_blocks (stderr, flags);
679 /* Remove local variables that are not referenced in the IL. */
682 remove_unused_locals (void)
686 referenced_var_iterator rvi;
687 bitmap global_unused_vars = NULL;
688 unsigned srcidx, dstidx, num;
689 bool have_local_clobbers = false;
691 /* Removing declarations from lexical blocks when not optimizing is
692 not only a waste of time, it actually causes differences in stack
697 timevar_push (TV_REMOVE_UNUSED);
699 mark_scope_block_unused (DECL_INITIAL (current_function_decl));
701 /* Assume all locals are unused. */
702 FOR_EACH_REFERENCED_VAR (cfun, t, rvi)
705 /* Walk the CFG marking all referenced symbols. */
708 gimple_stmt_iterator gsi;
713 /* Walk the statements. */
714 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
716 gimple stmt = gsi_stmt (gsi);
717 tree b = gimple_block (stmt);
719 if (is_gimple_debug (stmt))
722 if (gimple_clobber_p (stmt))
724 have_local_clobbers = true;
729 TREE_USED (b) = true;
731 for (i = 0; i < gimple_num_ops (stmt); i++)
732 mark_all_vars_used (gimple_op_ptr (gsi_stmt (gsi), i), NULL);
735 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
740 gimple phi = gsi_stmt (gsi);
742 /* No point processing globals. */
743 if (is_global_var (SSA_NAME_VAR (gimple_phi_result (phi))))
746 def = gimple_phi_result (phi);
747 mark_all_vars_used (&def, NULL);
749 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_ALL_USES)
751 tree arg = USE_FROM_PTR (arg_p);
752 mark_all_vars_used (&arg, NULL);
756 FOR_EACH_EDGE (e, ei, bb->succs)
758 TREE_USED (e->goto_block) = true;
761 /* We do a two-pass approach about the out-of-scope clobbers. We want
762 to remove them if they are the only references to a local variable,
763 but we want to retain them when there's any other. So the first pass
764 ignores them, and the second pass (if there were any) tries to remove
766 if (have_local_clobbers)
769 gimple_stmt_iterator gsi;
771 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
773 gimple stmt = gsi_stmt (gsi);
774 tree b = gimple_block (stmt);
776 if (gimple_clobber_p (stmt))
778 tree lhs = gimple_assign_lhs (stmt);
779 lhs = get_base_address (lhs);
780 if (TREE_CODE (lhs) == SSA_NAME)
781 lhs = SSA_NAME_VAR (lhs);
782 if (DECL_P (lhs) && (!var_ann (lhs) || !is_used_p (lhs)))
784 unlink_stmt_vdef (stmt);
785 gsi_remove (&gsi, true);
790 TREE_USED (b) = true;
796 cfun->has_local_explicit_reg_vars = false;
798 /* Remove unmarked local vars from local_decls. */
799 num = VEC_length (tree, cfun->local_decls);
800 for (srcidx = 0, dstidx = 0; srcidx < num; srcidx++)
802 var = VEC_index (tree, cfun->local_decls, srcidx);
803 if (TREE_CODE (var) != FUNCTION_DECL
805 || !is_used_p (var)))
807 if (is_global_var (var))
809 if (global_unused_vars == NULL)
810 global_unused_vars = BITMAP_ALLOC (NULL);
811 bitmap_set_bit (global_unused_vars, DECL_UID (var));
816 else if (TREE_CODE (var) == VAR_DECL
817 && DECL_HARD_REGISTER (var)
818 && !is_global_var (var))
819 cfun->has_local_explicit_reg_vars = true;
821 if (srcidx != dstidx)
822 VEC_replace (tree, cfun->local_decls, dstidx, var);
826 VEC_truncate (tree, cfun->local_decls, dstidx);
828 /* Remove unmarked global vars from local_decls. */
829 if (global_unused_vars != NULL)
833 FOR_EACH_LOCAL_DECL (cfun, ix, var)
834 if (TREE_CODE (var) == VAR_DECL
835 && is_global_var (var)
836 && var_ann (var) != NULL
838 && DECL_CONTEXT (var) == current_function_decl)
839 mark_all_vars_used (&DECL_INITIAL (var), global_unused_vars);
841 num = VEC_length (tree, cfun->local_decls);
842 for (srcidx = 0, dstidx = 0; srcidx < num; srcidx++)
844 var = VEC_index (tree, cfun->local_decls, srcidx);
845 if (TREE_CODE (var) == VAR_DECL
846 && is_global_var (var)
847 && bitmap_bit_p (global_unused_vars, DECL_UID (var)))
850 if (srcidx != dstidx)
851 VEC_replace (tree, cfun->local_decls, dstidx, var);
855 VEC_truncate (tree, cfun->local_decls, dstidx);
856 BITMAP_FREE (global_unused_vars);
859 /* Remove unused variables from REFERENCED_VARs. */
860 FOR_EACH_REFERENCED_VAR (cfun, t, rvi)
861 if (!is_global_var (t)
862 && TREE_CODE (t) != PARM_DECL
863 && TREE_CODE (t) != RESULT_DECL
865 remove_referenced_var (t);
866 remove_unused_scope_block_p (DECL_INITIAL (current_function_decl));
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);
877 /* Allocate and return a new live range information object base on MAP. */
879 static tree_live_info_p
880 new_tree_live_info (var_map map)
882 tree_live_info_p live;
885 live = (tree_live_info_p) xmalloc (sizeof (struct tree_live_info_d));
887 live->num_blocks = last_basic_block;
889 live->livein = (bitmap *)xmalloc (last_basic_block * sizeof (bitmap));
890 for (x = 0; x < (unsigned)last_basic_block; x++)
891 live->livein[x] = BITMAP_ALLOC (NULL);
893 live->liveout = (bitmap *)xmalloc (last_basic_block * sizeof (bitmap));
894 for (x = 0; x < (unsigned)last_basic_block; x++)
895 live->liveout[x] = BITMAP_ALLOC (NULL);
897 live->work_stack = XNEWVEC (int, last_basic_block);
898 live->stack_top = live->work_stack;
900 live->global = BITMAP_ALLOC (NULL);
905 /* Free storage for live range info object LIVE. */
908 delete_tree_live_info (tree_live_info_p live)
912 BITMAP_FREE (live->global);
913 free (live->work_stack);
915 for (x = live->num_blocks - 1; x >= 0; x--)
916 BITMAP_FREE (live->liveout[x]);
917 free (live->liveout);
919 for (x = live->num_blocks - 1; x >= 0; x--)
920 BITMAP_FREE (live->livein[x]);
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_assert (!TEST_BIT (visited, bb->index));
943 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)
951 /* TMP is 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 bitmap_and_compl (tmp, loe, live->liveout[pred_bb->index]);
957 /* Add these bits to live-on-entry for the pred. if there are any
958 changes, and pred_bb has been visited already, add it to the
960 change = bitmap_ior_into (live_on_entry (live, pred_bb), tmp);
961 if (TEST_BIT (visited, pred_bb->index) && change)
963 RESET_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 + 1);
979 bitmap tmp = BITMAP_ALLOC (NULL);
981 sbitmap_zero (visited);
983 /* Visit all the blocks in reverse order and propagate live on entry values
984 into the predecessors blocks. */
985 FOR_EACH_BB_REVERSE (bb)
986 loe_visit_block (live, bb, visited, tmp);
988 /* Process any blocks which require further iteration. */
989 while (live->stack_top != live->work_stack)
991 b = *--(live->stack_top);
992 loe_visit_block (live, BASIC_BLOCK (b), visited, tmp);
996 sbitmap_free (visited);
1000 /* Calculate the initial live on entry vector for SSA_NAME using immediate_use
1001 links. Set the live on entry fields in LIVE. Def's are marked temporarily
1002 in the liveout vector. */
1005 set_var_live_on_entry (tree ssa_name, tree_live_info_p live)
1010 basic_block def_bb = NULL;
1011 imm_use_iterator imm_iter;
1012 bool global = false;
1014 p = var_to_partition (live->map, ssa_name);
1015 if (p == NO_PARTITION)
1018 stmt = SSA_NAME_DEF_STMT (ssa_name);
1021 def_bb = gimple_bb (stmt);
1022 /* Mark defs in liveout bitmap temporarily. */
1024 bitmap_set_bit (live->liveout[def_bb->index], p);
1027 def_bb = ENTRY_BLOCK_PTR;
1029 /* Visit each use of SSA_NAME and if it isn't in the same block as the def,
1030 add it to the list of live on entry blocks. */
1031 FOR_EACH_IMM_USE_FAST (use, imm_iter, ssa_name)
1033 gimple use_stmt = USE_STMT (use);
1034 basic_block add_block = NULL;
1036 if (gimple_code (use_stmt) == GIMPLE_PHI)
1038 /* Uses in PHI's are considered to be live at exit of the SRC block
1039 as this is where a copy would be inserted. Check to see if it is
1040 defined in that block, or whether its live on entry. */
1041 int index = PHI_ARG_INDEX_FROM_USE (use);
1042 edge e = gimple_phi_arg_edge (use_stmt, index);
1043 if (e->src != ENTRY_BLOCK_PTR)
1045 if (e->src != def_bb)
1049 else if (is_gimple_debug (use_stmt))
1053 /* If its not defined in this block, its live on entry. */
1054 basic_block use_bb = gimple_bb (use_stmt);
1055 if (use_bb != def_bb)
1059 /* If there was a live on entry use, set the bit. */
1063 bitmap_set_bit (live->livein[add_block->index], p);
1067 /* If SSA_NAME is live on entry to at least one block, fill in all the live
1068 on entry blocks between the def and all the uses. */
1070 bitmap_set_bit (live->global, p);
1074 /* Calculate the live on exit vectors based on the entry info in LIVEINFO. */
1077 calculate_live_on_exit (tree_live_info_p liveinfo)
1083 /* live on entry calculations used liveout vectors for defs, clear them. */
1085 bitmap_clear (liveinfo->liveout[bb->index]);
1087 /* Set all the live-on-exit bits for uses in PHIs. */
1090 gimple_stmt_iterator gsi;
1093 /* Mark the PHI arguments which are live on exit to the pred block. */
1094 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1096 gimple phi = gsi_stmt (gsi);
1097 for (i = 0; i < gimple_phi_num_args (phi); i++)
1099 tree t = PHI_ARG_DEF (phi, i);
1102 if (TREE_CODE (t) != SSA_NAME)
1105 p = var_to_partition (liveinfo->map, t);
1106 if (p == NO_PARTITION)
1108 e = gimple_phi_arg_edge (phi, i);
1109 if (e->src != ENTRY_BLOCK_PTR)
1110 bitmap_set_bit (liveinfo->liveout[e->src->index], p);
1114 /* Add each successors live on entry to this bock live on exit. */
1115 FOR_EACH_EDGE (e, ei, bb->succs)
1116 if (e->dest != EXIT_BLOCK_PTR)
1117 bitmap_ior_into (liveinfo->liveout[bb->index],
1118 live_on_entry (liveinfo, e->dest));
1123 /* Given partition map MAP, calculate all the live on entry bitmaps for
1124 each partition. Return a new live info object. */
1127 calculate_live_ranges (var_map map)
1131 tree_live_info_p live;
1133 live = new_tree_live_info (map);
1134 for (i = 0; i < num_var_partitions (map); i++)
1136 var = partition_to_var (map, i);
1137 if (var != NULL_TREE)
1138 set_var_live_on_entry (var, live);
1141 live_worklist (live);
1143 #ifdef ENABLE_CHECKING
1144 verify_live_on_entry (live);
1147 calculate_live_on_exit (live);
1152 /* Output partition map MAP to file F. */
1155 dump_var_map (FILE *f, var_map map)
1161 fprintf (f, "\nPartition map \n\n");
1163 for (x = 0; x < map->num_partitions; x++)
1165 if (map->view_to_partition != NULL)
1166 p = map->view_to_partition[x];
1170 if (ssa_name (p) == NULL_TREE)
1174 for (y = 1; y < num_ssa_names; y++)
1176 p = partition_find (map->var_partition, y);
1177 if (map->partition_to_view)
1178 p = map->partition_to_view[p];
1183 fprintf(f, "Partition %d (", x);
1184 print_generic_expr (f, partition_to_var (map, p), TDF_SLIM);
1187 fprintf (f, "%d ", y);
1197 /* Output live range info LIVE to file F, controlled by FLAG. */
1200 dump_live_info (FILE *f, tree_live_info_p live, int flag)
1204 var_map map = live->map;
1207 if ((flag & LIVEDUMP_ENTRY) && live->livein)
1211 fprintf (f, "\nLive on entry to BB%d : ", bb->index);
1212 EXECUTE_IF_SET_IN_BITMAP (live->livein[bb->index], 0, i, bi)
1214 print_generic_expr (f, partition_to_var (map, i), TDF_SLIM);
1221 if ((flag & LIVEDUMP_EXIT) && live->liveout)
1225 fprintf (f, "\nLive on exit from BB%d : ", bb->index);
1226 EXECUTE_IF_SET_IN_BITMAP (live->liveout[bb->index], 0, i, bi)
1228 print_generic_expr (f, partition_to_var (map, i), TDF_SLIM);
1236 struct GTY(()) numbered_tree_d
1241 typedef struct numbered_tree_d numbered_tree;
1243 DEF_VEC_O (numbered_tree);
1244 DEF_VEC_ALLOC_O (numbered_tree, heap);
1246 /* Compare two declarations references by their DECL_UID / sequence number.
1247 Called via qsort. */
1250 compare_decls_by_uid (const void *pa, const void *pb)
1252 const numbered_tree *nt_a = ((const numbered_tree *)pa);
1253 const numbered_tree *nt_b = ((const numbered_tree *)pb);
1255 if (DECL_UID (nt_a->t) != DECL_UID (nt_b->t))
1256 return DECL_UID (nt_a->t) - DECL_UID (nt_b->t);
1257 return nt_a->num - nt_b->num;
1260 /* Called via walk_gimple_stmt / walk_gimple_op by dump_enumerated_decls. */
1262 dump_enumerated_decls_push (tree *tp, int *walk_subtrees, void *data)
1264 struct walk_stmt_info *wi = (struct walk_stmt_info *) data;
1265 VEC (numbered_tree, heap) **list = (VEC (numbered_tree, heap) **) &wi->info;
1271 nt.num = VEC_length (numbered_tree, *list);
1272 VEC_safe_push (numbered_tree, heap, *list, &nt);
1277 /* Find all the declarations used by the current function, sort them by uid,
1278 and emit the sorted list. Each declaration is tagged with a sequence
1279 number indicating when it was found during statement / tree walking,
1280 so that TDF_NOUID comparisons of anonymous declarations are still
1281 meaningful. Where a declaration was encountered more than once, we
1282 emit only the sequence number of the first encounter.
1283 FILE is the dump file where to output the list and FLAGS is as in
1284 print_generic_expr. */
1286 dump_enumerated_decls (FILE *file, int flags)
1289 struct walk_stmt_info wi;
1290 VEC (numbered_tree, heap) *decl_list = VEC_alloc (numbered_tree, heap, 40);
1292 memset (&wi, '\0', sizeof (wi));
1293 wi.info = (void*) decl_list;
1296 gimple_stmt_iterator gsi;
1298 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1299 if (!is_gimple_debug (gsi_stmt (gsi)))
1300 walk_gimple_stmt (&gsi, NULL, dump_enumerated_decls_push, &wi);
1302 decl_list = (VEC (numbered_tree, heap) *) wi.info;
1303 VEC_qsort (numbered_tree, decl_list, compare_decls_by_uid);
1304 if (VEC_length (numbered_tree, decl_list))
1308 tree last = NULL_TREE;
1310 fprintf (file, "Declarations used by %s, sorted by DECL_UID:\n",
1311 current_function_name ());
1312 FOR_EACH_VEC_ELT (numbered_tree, decl_list, ix, ntp)
1316 fprintf (file, "%d: ", ntp->num);
1317 print_generic_decl (file, ntp->t, flags);
1318 fprintf (file, "\n");
1322 VEC_free (numbered_tree, heap, decl_list);
1325 #ifdef ENABLE_CHECKING
1326 /* Verify that SSA_VAR is a non-virtual SSA_NAME. */
1329 register_ssa_partition_check (tree ssa_var)
1331 gcc_assert (TREE_CODE (ssa_var) == SSA_NAME);
1332 if (!is_gimple_reg (SSA_NAME_VAR (ssa_var)))
1334 fprintf (stderr, "Illegally registering a virtual SSA name :");
1335 print_generic_expr (stderr, ssa_var, TDF_SLIM);
1336 fprintf (stderr, " in the SSA->Normal phase.\n");
1337 internal_error ("SSA corruption");
1342 /* Verify that the info in LIVE matches the current cfg. */
1345 verify_live_on_entry (tree_live_info_p live)
1354 var_map map = live->map;
1356 /* Check for live on entry partitions and report those with a DEF in
1357 the program. This will typically mean an optimization has done
1359 bb = ENTRY_BLOCK_PTR;
1361 FOR_EACH_EDGE (e, ei, bb->succs)
1363 int entry_block = e->dest->index;
1364 if (e->dest == EXIT_BLOCK_PTR)
1366 for (i = 0; i < (unsigned)num_var_partitions (map); i++)
1371 var = partition_to_var (map, i);
1372 stmt = SSA_NAME_DEF_STMT (var);
1373 tmp = gimple_bb (stmt);
1374 d = gimple_default_def (cfun, SSA_NAME_VAR (var));
1376 loe = live_on_entry (live, e->dest);
1377 if (loe && bitmap_bit_p (loe, i))
1379 if (!gimple_nop_p (stmt))
1382 print_generic_expr (stderr, var, TDF_SLIM);
1383 fprintf (stderr, " is defined ");
1385 fprintf (stderr, " in BB%d, ", tmp->index);
1386 fprintf (stderr, "by:\n");
1387 print_gimple_stmt (stderr, stmt, 0, TDF_SLIM);
1388 fprintf (stderr, "\nIt is also live-on-entry to entry BB %d",
1390 fprintf (stderr, " So it appears to have multiple defs.\n");
1397 print_generic_expr (stderr, var, TDF_SLIM);
1398 fprintf (stderr, " is live-on-entry to BB%d ",
1402 fprintf (stderr, " but is not the default def of ");
1403 print_generic_expr (stderr, d, TDF_SLIM);
1404 fprintf (stderr, "\n");
1407 fprintf (stderr, " and there is no default def.\n");
1414 /* The only way this var shouldn't be marked live on entry is
1415 if it occurs in a PHI argument of the block. */
1418 gimple_stmt_iterator gsi;
1419 for (gsi = gsi_start_phis (e->dest);
1420 !gsi_end_p (gsi) && !ok;
1423 gimple phi = gsi_stmt (gsi);
1424 for (z = 0; z < gimple_phi_num_args (phi); z++)
1425 if (var == gimple_phi_arg_def (phi, z))
1434 print_generic_expr (stderr, var, TDF_SLIM);
1435 fprintf (stderr, " is not marked live-on-entry to entry BB%d ",
1437 fprintf (stderr, "but it is a default def so it should be.\n");
1441 gcc_assert (num <= 0);