1 /* Liveness for SSA trees.
2 Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009, 2010
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 Don't remove larger vars though, because BLOCK_VARS are
456 used also during expansion to determine which variables
457 might share stack space. */
458 else if (DECL_IGNORED_P (*t
) && is_gimple_reg (*t
))
460 *t
= DECL_CHAIN (*t
);
464 /* When we are outputting debug info, we usually want to output
465 info about optimized-out variables in the scope blocks.
466 Exception are the scope blocks not containing any instructions
467 at all so user can't get into the scopes at first place. */
468 else if (var_ann (*t
) != NULL
&& is_used_p (*t
))
470 else if (TREE_CODE (*t
) == LABEL_DECL
&& TREE_USED (*t
))
471 /* For labels that are still used in the IL, the decision to
472 preserve them must not depend DEBUG_INFO_LEVEL, otherwise we
473 risk having different ordering in debug vs. non-debug builds
474 during inlining or versioning.
475 A label appearing here (we have already checked DECL_IGNORED_P)
476 should not be used in the IL unless it has been explicitly used
477 before, so we use TREE_USED as an approximation. */
478 /* In principle, we should do the same here as for the debug case
479 below, however, when debugging, there might be additional nested
480 levels that keep an upper level with a label live, so we have to
481 force this block to be considered used, too. */
484 /* When we are not doing full debug info, we however can keep around
485 only the used variables for cfgexpand's memory packing saving quite
488 For sake of -g3, we keep around those vars but we don't count this as
489 use of block, so innermost block with no used vars and no instructions
490 can be considered dead. We only want to keep around blocks user can
491 breakpoint into and ask about value of optimized out variables.
493 Similarly we need to keep around types at least until all
494 variables of all nested blocks are gone. We track no
495 information on whether given type is used or not, so we have
496 to keep them even when not emitting debug information,
497 otherwise we may end up remapping variables and their (local)
498 types in different orders depending on whether debug
499 information is being generated. */
501 else if (TREE_CODE (*t
) == TYPE_DECL
502 || debug_info_level
== DINFO_LEVEL_NORMAL
503 || debug_info_level
== DINFO_LEVEL_VERBOSE
)
507 *t
= DECL_CHAIN (*t
);
512 for (t
= &BLOCK_SUBBLOCKS (scope
); *t
;)
513 if (remove_unused_scope_block_p (*t
))
515 if (BLOCK_SUBBLOCKS (*t
))
517 tree next
= BLOCK_CHAIN (*t
);
518 tree supercontext
= BLOCK_SUPERCONTEXT (*t
);
520 *t
= BLOCK_SUBBLOCKS (*t
);
521 while (BLOCK_CHAIN (*t
))
523 BLOCK_SUPERCONTEXT (*t
) = supercontext
;
524 t
= &BLOCK_CHAIN (*t
);
526 BLOCK_CHAIN (*t
) = next
;
527 BLOCK_SUPERCONTEXT (*t
) = supercontext
;
528 t
= &BLOCK_CHAIN (*t
);
532 *t
= BLOCK_CHAIN (*t
);
536 t
= &BLOCK_CHAIN (*t
);
543 /* Outer scope is always used. */
544 else if (!BLOCK_SUPERCONTEXT (scope
)
545 || TREE_CODE (BLOCK_SUPERCONTEXT (scope
)) == FUNCTION_DECL
)
547 /* Innermost blocks with no live variables nor statements can be always
549 else if (!nsubblocks
)
551 /* For terse debug info we can eliminate info on unused variables. */
552 else if (debug_info_level
== DINFO_LEVEL_NONE
553 || debug_info_level
== DINFO_LEVEL_TERSE
)
555 /* Even for -g0/-g1 don't prune outer scopes from artificial
556 functions, otherwise diagnostics using tree_nonartificial_location
557 will not be emitted properly. */
558 if (inlined_function_outer_scope_p (scope
))
563 && TREE_CODE (ao
) == BLOCK
564 && BLOCK_ABSTRACT_ORIGIN (ao
) != ao
)
565 ao
= BLOCK_ABSTRACT_ORIGIN (ao
);
567 && TREE_CODE (ao
) == FUNCTION_DECL
568 && DECL_DECLARED_INLINE_P (ao
)
569 && lookup_attribute ("artificial", DECL_ATTRIBUTES (ao
)))
573 else if (BLOCK_VARS (scope
) || BLOCK_NUM_NONLOCALIZED_VARS (scope
))
575 /* See if this block is important for representation of inlined function.
576 Inlined functions are always represented by block with
577 block_ultimate_origin being set to FUNCTION_DECL and DECL_SOURCE_LOCATION
579 else if (inlined_function_outer_scope_p (scope
))
582 /* Verfify that only blocks with source location set
583 are entry points to the inlined functions. */
584 gcc_assert (BLOCK_SOURCE_LOCATION (scope
) == UNKNOWN_LOCATION
);
586 TREE_USED (scope
) = !unused
;
590 /* Mark all VAR_DECLS under *EXPR_P as used, so that they won't be
591 eliminated during the tree->rtl conversion process. */
594 mark_all_vars_used (tree
*expr_p
, void *data
)
596 walk_tree (expr_p
, mark_all_vars_used_1
, data
, NULL
);
600 /* Dump scope blocks starting at SCOPE to FILE. INDENT is the
601 indentation level and FLAGS is as in print_generic_expr. */
604 dump_scope_block (FILE *file
, int indent
, tree scope
, int flags
)
609 fprintf (file
, "\n%*s{ Scope block #%i%s%s",indent
, "" , BLOCK_NUMBER (scope
),
610 TREE_USED (scope
) ? "" : " (unused)",
611 BLOCK_ABSTRACT (scope
) ? " (abstract)": "");
612 if (BLOCK_SOURCE_LOCATION (scope
) != UNKNOWN_LOCATION
)
614 expanded_location s
= expand_location (BLOCK_SOURCE_LOCATION (scope
));
615 fprintf (file
, " %s:%i", s
.file
, s
.line
);
617 if (BLOCK_ABSTRACT_ORIGIN (scope
))
619 tree origin
= block_ultimate_origin (scope
);
622 fprintf (file
, " Originating from :");
624 print_generic_decl (file
, origin
, flags
);
626 fprintf (file
, "#%i", BLOCK_NUMBER (origin
));
629 fprintf (file
, " \n");
630 for (var
= BLOCK_VARS (scope
); var
; var
= DECL_CHAIN (var
))
635 used
= is_used_p (var
);
637 fprintf (file
, "%*s", indent
, "");
638 print_generic_decl (file
, var
, flags
);
639 fprintf (file
, "%s\n", used
? "" : " (unused)");
641 for (i
= 0; i
< BLOCK_NUM_NONLOCALIZED_VARS (scope
); i
++)
643 fprintf (file
, "%*s",indent
, "");
644 print_generic_decl (file
, BLOCK_NONLOCALIZED_VAR (scope
, i
),
646 fprintf (file
, " (nonlocalized)\n");
648 for (t
= BLOCK_SUBBLOCKS (scope
); t
; t
= BLOCK_CHAIN (t
))
649 dump_scope_block (file
, indent
+ 2, t
, flags
);
650 fprintf (file
, "\n%*s}\n",indent
, "");
653 /* Dump the tree of lexical scopes starting at SCOPE to stderr. FLAGS
654 is as in print_generic_expr. */
657 debug_scope_block (tree scope
, int flags
)
659 dump_scope_block (stderr
, 0, scope
, flags
);
663 /* Dump the tree of lexical scopes of current_function_decl to FILE.
664 FLAGS is as in print_generic_expr. */
667 dump_scope_blocks (FILE *file
, int flags
)
669 dump_scope_block (file
, 0, DECL_INITIAL (current_function_decl
), flags
);
673 /* Dump the tree of lexical scopes of current_function_decl to stderr.
674 FLAGS is as in print_generic_expr. */
677 debug_scope_blocks (int flags
)
679 dump_scope_blocks (stderr
, flags
);
682 /* Remove local variables that are not referenced in the IL. */
685 remove_unused_locals (void)
689 referenced_var_iterator rvi
;
690 bitmap global_unused_vars
= NULL
;
691 unsigned srcidx
, dstidx
, num
;
692 bool have_local_clobbers
= false;
694 /* Removing declarations from lexical blocks when not optimizing is
695 not only a waste of time, it actually causes differences in stack
700 timevar_push (TV_REMOVE_UNUSED
);
702 mark_scope_block_unused (DECL_INITIAL (current_function_decl
));
704 /* Assume all locals are unused. */
705 FOR_EACH_REFERENCED_VAR (cfun
, t
, rvi
)
708 /* Walk the CFG marking all referenced symbols. */
711 gimple_stmt_iterator gsi
;
716 /* Walk the statements. */
717 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
719 gimple stmt
= gsi_stmt (gsi
);
720 tree b
= gimple_block (stmt
);
722 if (is_gimple_debug (stmt
))
725 if (gimple_clobber_p (stmt
))
727 have_local_clobbers
= true;
732 TREE_USED (b
) = true;
734 for (i
= 0; i
< gimple_num_ops (stmt
); i
++)
735 mark_all_vars_used (gimple_op_ptr (gsi_stmt (gsi
), i
), NULL
);
738 for (gsi
= gsi_start_phis (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
743 gimple phi
= gsi_stmt (gsi
);
745 /* No point processing globals. */
746 if (is_global_var (SSA_NAME_VAR (gimple_phi_result (phi
))))
749 def
= gimple_phi_result (phi
);
750 mark_all_vars_used (&def
, NULL
);
752 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_ALL_USES
)
754 tree arg
= USE_FROM_PTR (arg_p
);
755 mark_all_vars_used (&arg
, NULL
);
759 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
761 TREE_USED (e
->goto_block
) = true;
764 /* We do a two-pass approach about the out-of-scope clobbers. We want
765 to remove them if they are the only references to a local variable,
766 but we want to retain them when there's any other. So the first pass
767 ignores them, and the second pass (if there were any) tries to remove
769 if (have_local_clobbers
)
772 gimple_stmt_iterator gsi
;
774 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
);)
776 gimple stmt
= gsi_stmt (gsi
);
777 tree b
= gimple_block (stmt
);
779 if (gimple_clobber_p (stmt
))
781 tree lhs
= gimple_assign_lhs (stmt
);
782 lhs
= get_base_address (lhs
);
783 if (TREE_CODE (lhs
) == SSA_NAME
)
784 lhs
= SSA_NAME_VAR (lhs
);
785 if (DECL_P (lhs
) && (!var_ann (lhs
) || !is_used_p (lhs
)))
787 unlink_stmt_vdef (stmt
);
788 gsi_remove (&gsi
, true);
793 TREE_USED (b
) = true;
799 cfun
->has_local_explicit_reg_vars
= false;
801 /* Remove unmarked local vars from local_decls. */
802 num
= VEC_length (tree
, cfun
->local_decls
);
803 for (srcidx
= 0, dstidx
= 0; srcidx
< num
; srcidx
++)
805 var
= VEC_index (tree
, cfun
->local_decls
, srcidx
);
806 if (TREE_CODE (var
) != FUNCTION_DECL
808 || !is_used_p (var
)))
810 if (is_global_var (var
))
812 if (global_unused_vars
== NULL
)
813 global_unused_vars
= BITMAP_ALLOC (NULL
);
814 bitmap_set_bit (global_unused_vars
, DECL_UID (var
));
819 else if (TREE_CODE (var
) == VAR_DECL
820 && DECL_HARD_REGISTER (var
)
821 && !is_global_var (var
))
822 cfun
->has_local_explicit_reg_vars
= true;
824 if (srcidx
!= dstidx
)
825 VEC_replace (tree
, cfun
->local_decls
, dstidx
, var
);
829 VEC_truncate (tree
, cfun
->local_decls
, dstidx
);
831 /* Remove unmarked global vars from local_decls. */
832 if (global_unused_vars
!= NULL
)
836 FOR_EACH_LOCAL_DECL (cfun
, ix
, var
)
837 if (TREE_CODE (var
) == VAR_DECL
838 && is_global_var (var
)
839 && var_ann (var
) != NULL
841 && DECL_CONTEXT (var
) == current_function_decl
)
842 mark_all_vars_used (&DECL_INITIAL (var
), global_unused_vars
);
844 num
= VEC_length (tree
, cfun
->local_decls
);
845 for (srcidx
= 0, dstidx
= 0; srcidx
< num
; srcidx
++)
847 var
= VEC_index (tree
, cfun
->local_decls
, srcidx
);
848 if (TREE_CODE (var
) == VAR_DECL
849 && is_global_var (var
)
850 && bitmap_bit_p (global_unused_vars
, DECL_UID (var
)))
853 if (srcidx
!= dstidx
)
854 VEC_replace (tree
, cfun
->local_decls
, dstidx
, var
);
858 VEC_truncate (tree
, cfun
->local_decls
, dstidx
);
859 BITMAP_FREE (global_unused_vars
);
862 /* Remove unused variables from REFERENCED_VARs. */
863 FOR_EACH_REFERENCED_VAR (cfun
, t
, rvi
)
864 if (!is_global_var (t
)
865 && TREE_CODE (t
) != PARM_DECL
866 && TREE_CODE (t
) != RESULT_DECL
868 remove_referenced_var (t
);
869 remove_unused_scope_block_p (DECL_INITIAL (current_function_decl
));
870 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
872 fprintf (dump_file
, "Scope blocks after cleanups:\n");
873 dump_scope_blocks (dump_file
, dump_flags
);
876 timevar_pop (TV_REMOVE_UNUSED
);
880 /* Allocate and return a new live range information object base on MAP. */
882 static tree_live_info_p
883 new_tree_live_info (var_map map
)
885 tree_live_info_p live
;
888 live
= (tree_live_info_p
) xmalloc (sizeof (struct tree_live_info_d
));
890 live
->num_blocks
= last_basic_block
;
892 live
->livein
= (bitmap
*)xmalloc (last_basic_block
* sizeof (bitmap
));
893 for (x
= 0; x
< (unsigned)last_basic_block
; x
++)
894 live
->livein
[x
] = BITMAP_ALLOC (NULL
);
896 live
->liveout
= (bitmap
*)xmalloc (last_basic_block
* sizeof (bitmap
));
897 for (x
= 0; x
< (unsigned)last_basic_block
; x
++)
898 live
->liveout
[x
] = BITMAP_ALLOC (NULL
);
900 live
->work_stack
= XNEWVEC (int, last_basic_block
);
901 live
->stack_top
= live
->work_stack
;
903 live
->global
= BITMAP_ALLOC (NULL
);
908 /* Free storage for live range info object LIVE. */
911 delete_tree_live_info (tree_live_info_p live
)
915 BITMAP_FREE (live
->global
);
916 free (live
->work_stack
);
918 for (x
= live
->num_blocks
- 1; x
>= 0; x
--)
919 BITMAP_FREE (live
->liveout
[x
]);
920 free (live
->liveout
);
922 for (x
= live
->num_blocks
- 1; x
>= 0; x
--)
923 BITMAP_FREE (live
->livein
[x
]);
930 /* Visit basic block BB and propagate any required live on entry bits from
931 LIVE into the predecessors. VISITED is the bitmap of visited blocks.
932 TMP is a temporary work bitmap which is passed in to avoid reallocating
936 loe_visit_block (tree_live_info_p live
, basic_block bb
, sbitmap visited
,
944 gcc_assert (!TEST_BIT (visited
, bb
->index
));
946 SET_BIT (visited
, bb
->index
);
947 loe
= live_on_entry (live
, bb
);
949 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
952 if (pred_bb
== ENTRY_BLOCK_PTR
)
954 /* TMP is variables live-on-entry from BB that aren't defined in the
955 predecessor block. This should be the live on entry vars to pred.
956 Note that liveout is the DEFs in a block while live on entry is
958 bitmap_and_compl (tmp
, loe
, live
->liveout
[pred_bb
->index
]);
960 /* Add these bits to live-on-entry for the pred. if there are any
961 changes, and pred_bb has been visited already, add it to the
963 change
= bitmap_ior_into (live_on_entry (live
, pred_bb
), tmp
);
964 if (TEST_BIT (visited
, pred_bb
->index
) && change
)
966 RESET_BIT (visited
, pred_bb
->index
);
967 *(live
->stack_top
)++ = pred_bb
->index
;
973 /* Using LIVE, fill in all the live-on-entry blocks between the defs and uses
974 of all the variables. */
977 live_worklist (tree_live_info_p live
)
981 sbitmap visited
= sbitmap_alloc (last_basic_block
+ 1);
982 bitmap tmp
= BITMAP_ALLOC (NULL
);
984 sbitmap_zero (visited
);
986 /* Visit all the blocks in reverse order and propagate live on entry values
987 into the predecessors blocks. */
988 FOR_EACH_BB_REVERSE (bb
)
989 loe_visit_block (live
, bb
, visited
, tmp
);
991 /* Process any blocks which require further iteration. */
992 while (live
->stack_top
!= live
->work_stack
)
994 b
= *--(live
->stack_top
);
995 loe_visit_block (live
, BASIC_BLOCK (b
), visited
, tmp
);
999 sbitmap_free (visited
);
1003 /* Calculate the initial live on entry vector for SSA_NAME using immediate_use
1004 links. Set the live on entry fields in LIVE. Def's are marked temporarily
1005 in the liveout vector. */
1008 set_var_live_on_entry (tree ssa_name
, tree_live_info_p live
)
1013 basic_block def_bb
= NULL
;
1014 imm_use_iterator imm_iter
;
1015 bool global
= false;
1017 p
= var_to_partition (live
->map
, ssa_name
);
1018 if (p
== NO_PARTITION
)
1021 stmt
= SSA_NAME_DEF_STMT (ssa_name
);
1024 def_bb
= gimple_bb (stmt
);
1025 /* Mark defs in liveout bitmap temporarily. */
1027 bitmap_set_bit (live
->liveout
[def_bb
->index
], p
);
1030 def_bb
= ENTRY_BLOCK_PTR
;
1032 /* Visit each use of SSA_NAME and if it isn't in the same block as the def,
1033 add it to the list of live on entry blocks. */
1034 FOR_EACH_IMM_USE_FAST (use
, imm_iter
, ssa_name
)
1036 gimple use_stmt
= USE_STMT (use
);
1037 basic_block add_block
= NULL
;
1039 if (gimple_code (use_stmt
) == GIMPLE_PHI
)
1041 /* Uses in PHI's are considered to be live at exit of the SRC block
1042 as this is where a copy would be inserted. Check to see if it is
1043 defined in that block, or whether its live on entry. */
1044 int index
= PHI_ARG_INDEX_FROM_USE (use
);
1045 edge e
= gimple_phi_arg_edge (use_stmt
, index
);
1046 if (e
->src
!= ENTRY_BLOCK_PTR
)
1048 if (e
->src
!= def_bb
)
1052 else if (is_gimple_debug (use_stmt
))
1056 /* If its not defined in this block, its live on entry. */
1057 basic_block use_bb
= gimple_bb (use_stmt
);
1058 if (use_bb
!= def_bb
)
1062 /* If there was a live on entry use, set the bit. */
1066 bitmap_set_bit (live
->livein
[add_block
->index
], p
);
1070 /* If SSA_NAME is live on entry to at least one block, fill in all the live
1071 on entry blocks between the def and all the uses. */
1073 bitmap_set_bit (live
->global
, p
);
1077 /* Calculate the live on exit vectors based on the entry info in LIVEINFO. */
1080 calculate_live_on_exit (tree_live_info_p liveinfo
)
1086 /* live on entry calculations used liveout vectors for defs, clear them. */
1088 bitmap_clear (liveinfo
->liveout
[bb
->index
]);
1090 /* Set all the live-on-exit bits for uses in PHIs. */
1093 gimple_stmt_iterator gsi
;
1096 /* Mark the PHI arguments which are live on exit to the pred block. */
1097 for (gsi
= gsi_start_phis (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1099 gimple phi
= gsi_stmt (gsi
);
1100 for (i
= 0; i
< gimple_phi_num_args (phi
); i
++)
1102 tree t
= PHI_ARG_DEF (phi
, i
);
1105 if (TREE_CODE (t
) != SSA_NAME
)
1108 p
= var_to_partition (liveinfo
->map
, t
);
1109 if (p
== NO_PARTITION
)
1111 e
= gimple_phi_arg_edge (phi
, i
);
1112 if (e
->src
!= ENTRY_BLOCK_PTR
)
1113 bitmap_set_bit (liveinfo
->liveout
[e
->src
->index
], p
);
1117 /* Add each successors live on entry to this bock live on exit. */
1118 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1119 if (e
->dest
!= EXIT_BLOCK_PTR
)
1120 bitmap_ior_into (liveinfo
->liveout
[bb
->index
],
1121 live_on_entry (liveinfo
, e
->dest
));
1126 /* Given partition map MAP, calculate all the live on entry bitmaps for
1127 each partition. Return a new live info object. */
1130 calculate_live_ranges (var_map map
)
1134 tree_live_info_p live
;
1136 live
= new_tree_live_info (map
);
1137 for (i
= 0; i
< num_var_partitions (map
); i
++)
1139 var
= partition_to_var (map
, i
);
1140 if (var
!= NULL_TREE
)
1141 set_var_live_on_entry (var
, live
);
1144 live_worklist (live
);
1146 #ifdef ENABLE_CHECKING
1147 verify_live_on_entry (live
);
1150 calculate_live_on_exit (live
);
1155 /* Output partition map MAP to file F. */
1158 dump_var_map (FILE *f
, var_map map
)
1164 fprintf (f
, "\nPartition map \n\n");
1166 for (x
= 0; x
< map
->num_partitions
; x
++)
1168 if (map
->view_to_partition
!= NULL
)
1169 p
= map
->view_to_partition
[x
];
1173 if (ssa_name (p
) == NULL_TREE
)
1177 for (y
= 1; y
< num_ssa_names
; y
++)
1179 p
= partition_find (map
->var_partition
, y
);
1180 if (map
->partition_to_view
)
1181 p
= map
->partition_to_view
[p
];
1186 fprintf(f
, "Partition %d (", x
);
1187 print_generic_expr (f
, partition_to_var (map
, p
), TDF_SLIM
);
1190 fprintf (f
, "%d ", y
);
1200 /* Output live range info LIVE to file F, controlled by FLAG. */
1203 dump_live_info (FILE *f
, tree_live_info_p live
, int flag
)
1207 var_map map
= live
->map
;
1210 if ((flag
& LIVEDUMP_ENTRY
) && live
->livein
)
1214 fprintf (f
, "\nLive on entry to BB%d : ", bb
->index
);
1215 EXECUTE_IF_SET_IN_BITMAP (live
->livein
[bb
->index
], 0, i
, bi
)
1217 print_generic_expr (f
, partition_to_var (map
, i
), TDF_SLIM
);
1224 if ((flag
& LIVEDUMP_EXIT
) && live
->liveout
)
1228 fprintf (f
, "\nLive on exit from BB%d : ", bb
->index
);
1229 EXECUTE_IF_SET_IN_BITMAP (live
->liveout
[bb
->index
], 0, i
, bi
)
1231 print_generic_expr (f
, partition_to_var (map
, i
), TDF_SLIM
);
1239 struct GTY(()) numbered_tree_d
1244 typedef struct numbered_tree_d numbered_tree
;
1246 DEF_VEC_O (numbered_tree
);
1247 DEF_VEC_ALLOC_O (numbered_tree
, heap
);
1249 /* Compare two declarations references by their DECL_UID / sequence number.
1250 Called via qsort. */
1253 compare_decls_by_uid (const void *pa
, const void *pb
)
1255 const numbered_tree
*nt_a
= ((const numbered_tree
*)pa
);
1256 const numbered_tree
*nt_b
= ((const numbered_tree
*)pb
);
1258 if (DECL_UID (nt_a
->t
) != DECL_UID (nt_b
->t
))
1259 return DECL_UID (nt_a
->t
) - DECL_UID (nt_b
->t
);
1260 return nt_a
->num
- nt_b
->num
;
1263 /* Called via walk_gimple_stmt / walk_gimple_op by dump_enumerated_decls. */
1265 dump_enumerated_decls_push (tree
*tp
, int *walk_subtrees
, void *data
)
1267 struct walk_stmt_info
*wi
= (struct walk_stmt_info
*) data
;
1268 VEC (numbered_tree
, heap
) **list
= (VEC (numbered_tree
, heap
) **) &wi
->info
;
1274 nt
.num
= VEC_length (numbered_tree
, *list
);
1275 VEC_safe_push (numbered_tree
, heap
, *list
, &nt
);
1280 /* Find all the declarations used by the current function, sort them by uid,
1281 and emit the sorted list. Each declaration is tagged with a sequence
1282 number indicating when it was found during statement / tree walking,
1283 so that TDF_NOUID comparisons of anonymous declarations are still
1284 meaningful. Where a declaration was encountered more than once, we
1285 emit only the sequence number of the first encounter.
1286 FILE is the dump file where to output the list and FLAGS is as in
1287 print_generic_expr. */
1289 dump_enumerated_decls (FILE *file
, int flags
)
1292 struct walk_stmt_info wi
;
1293 VEC (numbered_tree
, heap
) *decl_list
= VEC_alloc (numbered_tree
, heap
, 40);
1295 memset (&wi
, '\0', sizeof (wi
));
1296 wi
.info
= (void*) decl_list
;
1299 gimple_stmt_iterator gsi
;
1301 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1302 if (!is_gimple_debug (gsi_stmt (gsi
)))
1303 walk_gimple_stmt (&gsi
, NULL
, dump_enumerated_decls_push
, &wi
);
1305 decl_list
= (VEC (numbered_tree
, heap
) *) wi
.info
;
1306 VEC_qsort (numbered_tree
, decl_list
, compare_decls_by_uid
);
1307 if (VEC_length (numbered_tree
, decl_list
))
1311 tree last
= NULL_TREE
;
1313 fprintf (file
, "Declarations used by %s, sorted by DECL_UID:\n",
1314 current_function_name ());
1315 FOR_EACH_VEC_ELT (numbered_tree
, decl_list
, ix
, ntp
)
1319 fprintf (file
, "%d: ", ntp
->num
);
1320 print_generic_decl (file
, ntp
->t
, flags
);
1321 fprintf (file
, "\n");
1325 VEC_free (numbered_tree
, heap
, decl_list
);
1328 #ifdef ENABLE_CHECKING
1329 /* Verify that SSA_VAR is a non-virtual SSA_NAME. */
1332 register_ssa_partition_check (tree ssa_var
)
1334 gcc_assert (TREE_CODE (ssa_var
) == SSA_NAME
);
1335 if (!is_gimple_reg (SSA_NAME_VAR (ssa_var
)))
1337 fprintf (stderr
, "Illegally registering a virtual SSA name :");
1338 print_generic_expr (stderr
, ssa_var
, TDF_SLIM
);
1339 fprintf (stderr
, " in the SSA->Normal phase.\n");
1340 internal_error ("SSA corruption");
1345 /* Verify that the info in LIVE matches the current cfg. */
1348 verify_live_on_entry (tree_live_info_p live
)
1357 var_map map
= live
->map
;
1359 /* Check for live on entry partitions and report those with a DEF in
1360 the program. This will typically mean an optimization has done
1362 bb
= ENTRY_BLOCK_PTR
;
1364 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1366 int entry_block
= e
->dest
->index
;
1367 if (e
->dest
== EXIT_BLOCK_PTR
)
1369 for (i
= 0; i
< (unsigned)num_var_partitions (map
); i
++)
1374 var
= partition_to_var (map
, i
);
1375 stmt
= SSA_NAME_DEF_STMT (var
);
1376 tmp
= gimple_bb (stmt
);
1377 d
= gimple_default_def (cfun
, SSA_NAME_VAR (var
));
1379 loe
= live_on_entry (live
, e
->dest
);
1380 if (loe
&& bitmap_bit_p (loe
, i
))
1382 if (!gimple_nop_p (stmt
))
1385 print_generic_expr (stderr
, var
, TDF_SLIM
);
1386 fprintf (stderr
, " is defined ");
1388 fprintf (stderr
, " in BB%d, ", tmp
->index
);
1389 fprintf (stderr
, "by:\n");
1390 print_gimple_stmt (stderr
, stmt
, 0, TDF_SLIM
);
1391 fprintf (stderr
, "\nIt is also live-on-entry to entry BB %d",
1393 fprintf (stderr
, " So it appears to have multiple defs.\n");
1400 print_generic_expr (stderr
, var
, TDF_SLIM
);
1401 fprintf (stderr
, " is live-on-entry to BB%d ",
1405 fprintf (stderr
, " but is not the default def of ");
1406 print_generic_expr (stderr
, d
, TDF_SLIM
);
1407 fprintf (stderr
, "\n");
1410 fprintf (stderr
, " and there is no default def.\n");
1417 /* The only way this var shouldn't be marked live on entry is
1418 if it occurs in a PHI argument of the block. */
1421 gimple_stmt_iterator gsi
;
1422 for (gsi
= gsi_start_phis (e
->dest
);
1423 !gsi_end_p (gsi
) && !ok
;
1426 gimple phi
= gsi_stmt (gsi
);
1427 for (z
= 0; z
< gimple_phi_num_args (phi
); z
++)
1428 if (var
== gimple_phi_arg_def (phi
, z
))
1437 print_generic_expr (stderr
, var
, TDF_SLIM
);
1438 fprintf (stderr
, " is not marked live-on-entry to entry BB%d ",
1440 fprintf (stderr
, "but it is a default def so it should be.\n");
1444 gcc_assert (num
<= 0);