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
)
351 bitmap global_unused_vars
= (bitmap
)data
;
353 enum tree_code_class c
= TREE_CODE_CLASS (TREE_CODE (t
));
356 if (TREE_CODE (t
) == SSA_NAME
)
357 t
= SSA_NAME_VAR (t
);
359 if (IS_EXPR_CODE_CLASS (c
)
360 && (b
= TREE_BLOCK (t
)) != NULL
)
361 TREE_USED (b
) = true;
363 /* Ignore TMR_OFFSET and TMR_STEP for TARGET_MEM_REFS, as those
364 fields do not contain vars. */
365 if (TREE_CODE (t
) == TARGET_MEM_REF
)
367 mark_all_vars_used (&TMR_BASE (t
), data
);
368 mark_all_vars_used (&TMR_INDEX (t
), data
);
369 mark_all_vars_used (&TMR_INDEX2 (t
), data
);
374 /* Only need to mark VAR_DECLS; parameters and return results are not
375 eliminated as unused. */
376 if (TREE_CODE (t
) == VAR_DECL
)
378 /* Global vars do not have a var-annotation so their use is tracked
379 with the global_unused_vars bitmap. Also walk their initializer
380 when they are first recognized as used. */
381 if (is_global_var (t
))
383 if (bitmap_clear_bit (global_unused_vars
, DECL_UID (t
)))
384 mark_all_vars_used (&DECL_INITIAL (t
), data
);
389 /* remove_unused_scope_block_p requires information about labels
390 which are not DECL_IGNORED_P to tell if they might be used in the IL. */
391 else if (TREE_CODE (t
) == LABEL_DECL
)
392 /* Although the TREE_USED values that the frontend uses would be
393 acceptable (albeit slightly over-conservative) for our purposes,
394 init_vars_expansion clears TREE_USED for LABEL_DECLs too, so we
395 must re-compute it here. */
398 if (IS_TYPE_OR_DECL_P (t
))
404 /* Mark the scope block SCOPE and its subblocks unused when they can be
405 possibly eliminated if dead. */
408 mark_scope_block_unused (tree scope
)
411 TREE_USED (scope
) = false;
412 if (!(*debug_hooks
->ignore_block
) (scope
))
413 TREE_USED (scope
) = true;
414 for (t
= BLOCK_SUBBLOCKS (scope
); t
; t
= BLOCK_CHAIN (t
))
415 mark_scope_block_unused (t
);
418 /* Look if the block is dead (by possibly eliminating its dead subblocks)
419 and return true if so.
420 Block is declared dead if:
421 1) No statements are associated with it.
422 2) Declares no live variables
423 3) All subblocks are dead
424 or there is precisely one subblocks and the block
425 has same abstract origin as outer block and declares
426 no variables, so it is pure wrapper.
427 When we are not outputting full debug info, we also eliminate dead variables
428 out of scope blocks to let them to be recycled by GGC and to save copying work
429 done by the inliner. */
432 remove_unused_scope_block_p (tree scope
, bitmap global_unused_vars
)
435 bool unused
= !TREE_USED (scope
);
438 for (t
= &BLOCK_VARS (scope
); *t
; t
= next
)
440 next
= &DECL_CHAIN (*t
);
442 /* Debug info of nested function refers to the block of the
443 function. We might stil call it even if all statements
444 of function it was nested into was elliminated.
446 TODO: We can actually look into cgraph to see if function
447 will be output to file. */
448 if (TREE_CODE (*t
) == FUNCTION_DECL
)
451 /* If a decl has a value expr, we need to instantiate it
452 regardless of debug info generation, to avoid codegen
453 differences in memory overlap tests. update_equiv_regs() may
454 indirectly call validate_equiv_mem() to test whether a
455 SET_DEST overlaps with others, and if the value expr changes
456 by virtual register instantiation, we may get end up with
457 different results. */
458 else if (TREE_CODE (*t
) == VAR_DECL
&& DECL_HAS_VALUE_EXPR_P (*t
))
461 /* Remove everything we don't generate debug info for.
462 Don't remove larger vars though, because BLOCK_VARS are
463 used also during expansion to determine which variables
464 might share stack space. */
465 else if (DECL_IGNORED_P (*t
) && is_gimple_reg (*t
))
467 *t
= DECL_CHAIN (*t
);
471 /* When we are outputting debug info, we usually want to output
472 info about optimized-out variables in the scope blocks.
473 Exception are the scope blocks not containing any instructions
474 at all so user can't get into the scopes at first place. */
475 else if ((is_global_var (*t
)
476 && !bitmap_bit_p (global_unused_vars
, DECL_UID (*t
)))
477 || (var_ann (*t
) != NULL
&& is_used_p (*t
)))
479 else if (TREE_CODE (*t
) == LABEL_DECL
&& TREE_USED (*t
))
480 /* For labels that are still used in the IL, the decision to
481 preserve them must not depend DEBUG_INFO_LEVEL, otherwise we
482 risk having different ordering in debug vs. non-debug builds
483 during inlining or versioning.
484 A label appearing here (we have already checked DECL_IGNORED_P)
485 should not be used in the IL unless it has been explicitly used
486 before, so we use TREE_USED as an approximation. */
487 /* In principle, we should do the same here as for the debug case
488 below, however, when debugging, there might be additional nested
489 levels that keep an upper level with a label live, so we have to
490 force this block to be considered used, too. */
493 /* When we are not doing full debug info, we however can keep around
494 only the used variables for cfgexpand's memory packing saving quite
497 For sake of -g3, we keep around those vars but we don't count this as
498 use of block, so innermost block with no used vars and no instructions
499 can be considered dead. We only want to keep around blocks user can
500 breakpoint into and ask about value of optimized out variables.
502 Similarly we need to keep around types at least until all
503 variables of all nested blocks are gone. We track no
504 information on whether given type is used or not, so we have
505 to keep them even when not emitting debug information,
506 otherwise we may end up remapping variables and their (local)
507 types in different orders depending on whether debug
508 information is being generated. */
510 else if (TREE_CODE (*t
) == TYPE_DECL
511 || debug_info_level
== DINFO_LEVEL_NORMAL
512 || debug_info_level
== DINFO_LEVEL_VERBOSE
)
516 *t
= DECL_CHAIN (*t
);
521 for (t
= &BLOCK_SUBBLOCKS (scope
); *t
;)
522 if (remove_unused_scope_block_p (*t
, global_unused_vars
))
524 if (BLOCK_SUBBLOCKS (*t
))
526 tree next
= BLOCK_CHAIN (*t
);
527 tree supercontext
= BLOCK_SUPERCONTEXT (*t
);
529 *t
= BLOCK_SUBBLOCKS (*t
);
530 while (BLOCK_CHAIN (*t
))
532 BLOCK_SUPERCONTEXT (*t
) = supercontext
;
533 t
= &BLOCK_CHAIN (*t
);
535 BLOCK_CHAIN (*t
) = next
;
536 BLOCK_SUPERCONTEXT (*t
) = supercontext
;
537 t
= &BLOCK_CHAIN (*t
);
541 *t
= BLOCK_CHAIN (*t
);
545 t
= &BLOCK_CHAIN (*t
);
552 /* Outer scope is always used. */
553 else if (!BLOCK_SUPERCONTEXT (scope
)
554 || TREE_CODE (BLOCK_SUPERCONTEXT (scope
)) == FUNCTION_DECL
)
556 /* Innermost blocks with no live variables nor statements can be always
558 else if (!nsubblocks
)
560 /* For terse debug info we can eliminate info on unused variables. */
561 else if (debug_info_level
== DINFO_LEVEL_NONE
562 || debug_info_level
== DINFO_LEVEL_TERSE
)
564 /* Even for -g0/-g1 don't prune outer scopes from artificial
565 functions, otherwise diagnostics using tree_nonartificial_location
566 will not be emitted properly. */
567 if (inlined_function_outer_scope_p (scope
))
572 && TREE_CODE (ao
) == BLOCK
573 && BLOCK_ABSTRACT_ORIGIN (ao
) != ao
)
574 ao
= BLOCK_ABSTRACT_ORIGIN (ao
);
576 && TREE_CODE (ao
) == FUNCTION_DECL
577 && DECL_DECLARED_INLINE_P (ao
)
578 && lookup_attribute ("artificial", DECL_ATTRIBUTES (ao
)))
582 else if (BLOCK_VARS (scope
) || BLOCK_NUM_NONLOCALIZED_VARS (scope
))
584 /* See if this block is important for representation of inlined function.
585 Inlined functions are always represented by block with
586 block_ultimate_origin being set to FUNCTION_DECL and DECL_SOURCE_LOCATION
588 else if (inlined_function_outer_scope_p (scope
))
591 /* Verfify that only blocks with source location set
592 are entry points to the inlined functions. */
593 gcc_assert (BLOCK_SOURCE_LOCATION (scope
) == UNKNOWN_LOCATION
);
595 TREE_USED (scope
) = !unused
;
599 /* Mark all VAR_DECLS under *EXPR_P as used, so that they won't be
600 eliminated during the tree->rtl conversion process. */
603 mark_all_vars_used (tree
*expr_p
, void *data
)
605 walk_tree (expr_p
, mark_all_vars_used_1
, data
, NULL
);
609 /* Dump scope blocks starting at SCOPE to FILE. INDENT is the
610 indentation level and FLAGS is as in print_generic_expr. */
613 dump_scope_block (FILE *file
, int indent
, tree scope
, int flags
)
618 fprintf (file
, "\n%*s{ Scope block #%i%s%s",indent
, "" , BLOCK_NUMBER (scope
),
619 TREE_USED (scope
) ? "" : " (unused)",
620 BLOCK_ABSTRACT (scope
) ? " (abstract)": "");
621 if (BLOCK_SOURCE_LOCATION (scope
) != UNKNOWN_LOCATION
)
623 expanded_location s
= expand_location (BLOCK_SOURCE_LOCATION (scope
));
624 fprintf (file
, " %s:%i", s
.file
, s
.line
);
626 if (BLOCK_ABSTRACT_ORIGIN (scope
))
628 tree origin
= block_ultimate_origin (scope
);
631 fprintf (file
, " Originating from :");
633 print_generic_decl (file
, origin
, flags
);
635 fprintf (file
, "#%i", BLOCK_NUMBER (origin
));
638 fprintf (file
, " \n");
639 for (var
= BLOCK_VARS (scope
); var
; var
= DECL_CHAIN (var
))
644 used
= is_used_p (var
);
646 fprintf (file
, "%*s", indent
, "");
647 print_generic_decl (file
, var
, flags
);
648 fprintf (file
, "%s\n", used
? "" : " (unused)");
650 for (i
= 0; i
< BLOCK_NUM_NONLOCALIZED_VARS (scope
); i
++)
652 fprintf (file
, "%*s",indent
, "");
653 print_generic_decl (file
, BLOCK_NONLOCALIZED_VAR (scope
, i
),
655 fprintf (file
, " (nonlocalized)\n");
657 for (t
= BLOCK_SUBBLOCKS (scope
); t
; t
= BLOCK_CHAIN (t
))
658 dump_scope_block (file
, indent
+ 2, t
, flags
);
659 fprintf (file
, "\n%*s}\n",indent
, "");
662 /* Dump the tree of lexical scopes starting at SCOPE to stderr. FLAGS
663 is as in print_generic_expr. */
666 debug_scope_block (tree scope
, int flags
)
668 dump_scope_block (stderr
, 0, scope
, flags
);
672 /* Dump the tree of lexical scopes of current_function_decl to FILE.
673 FLAGS is as in print_generic_expr. */
676 dump_scope_blocks (FILE *file
, int flags
)
678 dump_scope_block (file
, 0, DECL_INITIAL (current_function_decl
), flags
);
682 /* Dump the tree of lexical scopes of current_function_decl to stderr.
683 FLAGS is as in print_generic_expr. */
686 debug_scope_blocks (int flags
)
688 dump_scope_blocks (stderr
, flags
);
691 /* Remove local variables that are not referenced in the IL. */
694 remove_unused_locals (void)
698 referenced_var_iterator rvi
;
699 bitmap global_unused_vars
= NULL
;
700 unsigned srcidx
, dstidx
, num
, ix
;
701 bool have_local_clobbers
= false;
703 /* Removing declarations from lexical blocks when not optimizing is
704 not only a waste of time, it actually causes differences in stack
709 timevar_push (TV_REMOVE_UNUSED
);
711 mark_scope_block_unused (DECL_INITIAL (current_function_decl
));
713 /* Assume all locals are unused. */
714 FOR_EACH_REFERENCED_VAR (cfun
, t
, rvi
)
717 /* Assume all globals in local decls are unused. */
718 global_unused_vars
= BITMAP_ALLOC (NULL
);
719 FOR_EACH_LOCAL_DECL (cfun
, ix
, var
)
720 if (TREE_CODE (var
) == VAR_DECL
721 && is_global_var (var
))
722 bitmap_set_bit (global_unused_vars
, DECL_UID (var
));
724 /* Walk the CFG marking all referenced symbols. */
727 gimple_stmt_iterator gsi
;
732 /* Walk the statements. */
733 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
735 gimple stmt
= gsi_stmt (gsi
);
736 tree b
= gimple_block (stmt
);
738 if (is_gimple_debug (stmt
))
741 if (gimple_clobber_p (stmt
))
743 have_local_clobbers
= true;
748 TREE_USED (b
) = true;
750 for (i
= 0; i
< gimple_num_ops (stmt
); i
++)
751 mark_all_vars_used (gimple_op_ptr (gsi_stmt (gsi
), i
),
755 for (gsi
= gsi_start_phis (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
760 gimple phi
= gsi_stmt (gsi
);
762 if (!is_gimple_reg (gimple_phi_result (phi
)))
765 def
= gimple_phi_result (phi
);
766 mark_all_vars_used (&def
, global_unused_vars
);
768 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_ALL_USES
)
770 tree arg
= USE_FROM_PTR (arg_p
);
771 mark_all_vars_used (&arg
, global_unused_vars
);
775 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
777 TREE_USED (e
->goto_block
) = true;
780 /* We do a two-pass approach about the out-of-scope clobbers. We want
781 to remove them if they are the only references to a local variable,
782 but we want to retain them when there's any other. So the first pass
783 ignores them, and the second pass (if there were any) tries to remove
785 if (have_local_clobbers
)
788 gimple_stmt_iterator gsi
;
790 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
);)
792 gimple stmt
= gsi_stmt (gsi
);
793 tree b
= gimple_block (stmt
);
795 if (gimple_clobber_p (stmt
))
797 tree lhs
= gimple_assign_lhs (stmt
);
798 lhs
= get_base_address (lhs
);
799 if (TREE_CODE (lhs
) == SSA_NAME
)
800 lhs
= SSA_NAME_VAR (lhs
);
801 if (TREE_CODE (lhs
) == VAR_DECL
802 && ((is_global_var (lhs
)
803 && bitmap_bit_p (global_unused_vars
, DECL_UID (lhs
)))
804 || (!is_global_var (lhs
) && !is_used_p (lhs
))))
806 unlink_stmt_vdef (stmt
);
807 gsi_remove (&gsi
, true);
812 TREE_USED (b
) = true;
818 cfun
->has_local_explicit_reg_vars
= false;
820 /* Remove unmarked local and global vars from local_decls
821 and referenced vars. */
822 num
= VEC_length (tree
, cfun
->local_decls
);
823 for (srcidx
= 0, dstidx
= 0; srcidx
< num
; srcidx
++)
825 var
= VEC_index (tree
, cfun
->local_decls
, srcidx
);
826 if (TREE_CODE (var
) == VAR_DECL
)
828 if (is_global_var (var
))
830 if (bitmap_bit_p (global_unused_vars
, DECL_UID (var
)))
833 else if (var_ann (var
) == NULL
837 remove_referenced_var (var
);
838 if (cfun
->nonlocal_goto_save_area
839 && TREE_OPERAND (cfun
->nonlocal_goto_save_area
, 0) == var
)
840 cfun
->nonlocal_goto_save_area
= NULL
;
844 if (TREE_CODE (var
) == VAR_DECL
845 && DECL_HARD_REGISTER (var
)
846 && !is_global_var (var
))
847 cfun
->has_local_explicit_reg_vars
= true;
849 if (srcidx
!= dstidx
)
850 VEC_replace (tree
, cfun
->local_decls
, dstidx
, var
);
854 VEC_truncate (tree
, cfun
->local_decls
, dstidx
);
856 /* ??? We end up with decls in referenced-vars that are not in
858 FOR_EACH_REFERENCED_VAR (cfun
, t
, rvi
)
859 if (TREE_CODE (t
) == VAR_DECL
860 && !VAR_DECL_IS_VIRTUAL_OPERAND (t
)
862 remove_referenced_var (t
);
864 remove_unused_scope_block_p (DECL_INITIAL (current_function_decl
),
867 BITMAP_FREE (global_unused_vars
);
869 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
871 fprintf (dump_file
, "Scope blocks after cleanups:\n");
872 dump_scope_blocks (dump_file
, dump_flags
);
875 timevar_pop (TV_REMOVE_UNUSED
);
879 /* Allocate and return a new live range information object base on MAP. */
881 static tree_live_info_p
882 new_tree_live_info (var_map map
)
884 tree_live_info_p live
;
887 live
= (tree_live_info_p
) xmalloc (sizeof (struct tree_live_info_d
));
889 live
->num_blocks
= last_basic_block
;
891 live
->livein
= (bitmap
*)xmalloc (last_basic_block
* sizeof (bitmap
));
892 for (x
= 0; x
< (unsigned)last_basic_block
; x
++)
893 live
->livein
[x
] = BITMAP_ALLOC (NULL
);
895 live
->liveout
= (bitmap
*)xmalloc (last_basic_block
* sizeof (bitmap
));
896 for (x
= 0; x
< (unsigned)last_basic_block
; x
++)
897 live
->liveout
[x
] = BITMAP_ALLOC (NULL
);
899 live
->work_stack
= XNEWVEC (int, last_basic_block
);
900 live
->stack_top
= live
->work_stack
;
902 live
->global
= BITMAP_ALLOC (NULL
);
907 /* Free storage for live range info object LIVE. */
910 delete_tree_live_info (tree_live_info_p live
)
914 BITMAP_FREE (live
->global
);
915 free (live
->work_stack
);
917 for (x
= live
->num_blocks
- 1; x
>= 0; x
--)
918 BITMAP_FREE (live
->liveout
[x
]);
919 free (live
->liveout
);
921 for (x
= live
->num_blocks
- 1; x
>= 0; x
--)
922 BITMAP_FREE (live
->livein
[x
]);
929 /* Visit basic block BB and propagate any required live on entry bits from
930 LIVE into the predecessors. VISITED is the bitmap of visited blocks.
931 TMP is a temporary work bitmap which is passed in to avoid reallocating
935 loe_visit_block (tree_live_info_p live
, basic_block bb
, sbitmap visited
,
943 gcc_assert (!TEST_BIT (visited
, bb
->index
));
945 SET_BIT (visited
, bb
->index
);
946 loe
= live_on_entry (live
, bb
);
948 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
951 if (pred_bb
== ENTRY_BLOCK_PTR
)
953 /* TMP is variables live-on-entry from BB that aren't defined in the
954 predecessor block. This should be the live on entry vars to pred.
955 Note that liveout is the DEFs in a block while live on entry is
957 bitmap_and_compl (tmp
, loe
, live
->liveout
[pred_bb
->index
]);
959 /* Add these bits to live-on-entry for the pred. if there are any
960 changes, and pred_bb has been visited already, add it to the
962 change
= bitmap_ior_into (live_on_entry (live
, pred_bb
), tmp
);
963 if (TEST_BIT (visited
, pred_bb
->index
) && change
)
965 RESET_BIT (visited
, pred_bb
->index
);
966 *(live
->stack_top
)++ = pred_bb
->index
;
972 /* Using LIVE, fill in all the live-on-entry blocks between the defs and uses
973 of all the variables. */
976 live_worklist (tree_live_info_p live
)
980 sbitmap visited
= sbitmap_alloc (last_basic_block
+ 1);
981 bitmap tmp
= BITMAP_ALLOC (NULL
);
983 sbitmap_zero (visited
);
985 /* Visit all the blocks in reverse order and propagate live on entry values
986 into the predecessors blocks. */
987 FOR_EACH_BB_REVERSE (bb
)
988 loe_visit_block (live
, bb
, visited
, tmp
);
990 /* Process any blocks which require further iteration. */
991 while (live
->stack_top
!= live
->work_stack
)
993 b
= *--(live
->stack_top
);
994 loe_visit_block (live
, BASIC_BLOCK (b
), visited
, tmp
);
998 sbitmap_free (visited
);
1002 /* Calculate the initial live on entry vector for SSA_NAME using immediate_use
1003 links. Set the live on entry fields in LIVE. Def's are marked temporarily
1004 in the liveout vector. */
1007 set_var_live_on_entry (tree ssa_name
, tree_live_info_p live
)
1012 basic_block def_bb
= NULL
;
1013 imm_use_iterator imm_iter
;
1014 bool global
= false;
1016 p
= var_to_partition (live
->map
, ssa_name
);
1017 if (p
== NO_PARTITION
)
1020 stmt
= SSA_NAME_DEF_STMT (ssa_name
);
1023 def_bb
= gimple_bb (stmt
);
1024 /* Mark defs in liveout bitmap temporarily. */
1026 bitmap_set_bit (live
->liveout
[def_bb
->index
], p
);
1029 def_bb
= ENTRY_BLOCK_PTR
;
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 (use_stmt
, index
);
1045 if (e
->src
!= ENTRY_BLOCK_PTR
)
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. */
1087 bitmap_clear (liveinfo
->liveout
[bb
->index
]);
1089 /* Set all the live-on-exit bits for uses in PHIs. */
1092 gimple_stmt_iterator gsi
;
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 gimple phi
= gsi_stmt (gsi
);
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
)
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
)
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
)
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
);
1145 #ifdef ENABLE_CHECKING
1146 verify_live_on_entry (live
);
1149 calculate_live_on_exit (live
);
1154 /* Output partition map MAP to file F. */
1157 dump_var_map (FILE *f
, var_map map
)
1163 fprintf (f
, "\nPartition map \n\n");
1165 for (x
= 0; x
< map
->num_partitions
; x
++)
1167 if (map
->view_to_partition
!= NULL
)
1168 p
= map
->view_to_partition
[x
];
1172 if (ssa_name (p
) == NULL_TREE
)
1176 for (y
= 1; y
< num_ssa_names
; y
++)
1178 p
= partition_find (map
->var_partition
, y
);
1179 if (map
->partition_to_view
)
1180 p
= map
->partition_to_view
[p
];
1185 fprintf(f
, "Partition %d (", x
);
1186 print_generic_expr (f
, partition_to_var (map
, p
), TDF_SLIM
);
1189 fprintf (f
, "%d ", y
);
1199 /* Output live range info LIVE to file F, controlled by FLAG. */
1202 dump_live_info (FILE *f
, tree_live_info_p live
, int flag
)
1206 var_map map
= live
->map
;
1209 if ((flag
& LIVEDUMP_ENTRY
) && live
->livein
)
1213 fprintf (f
, "\nLive on entry to BB%d : ", bb
->index
);
1214 EXECUTE_IF_SET_IN_BITMAP (live
->livein
[bb
->index
], 0, i
, bi
)
1216 print_generic_expr (f
, partition_to_var (map
, i
), TDF_SLIM
);
1223 if ((flag
& LIVEDUMP_EXIT
) && live
->liveout
)
1227 fprintf (f
, "\nLive on exit from BB%d : ", bb
->index
);
1228 EXECUTE_IF_SET_IN_BITMAP (live
->liveout
[bb
->index
], 0, i
, bi
)
1230 print_generic_expr (f
, partition_to_var (map
, i
), TDF_SLIM
);
1238 struct GTY(()) numbered_tree_d
1243 typedef struct numbered_tree_d numbered_tree
;
1245 DEF_VEC_O (numbered_tree
);
1246 DEF_VEC_ALLOC_O (numbered_tree
, heap
);
1248 /* Compare two declarations references by their DECL_UID / sequence number.
1249 Called via qsort. */
1252 compare_decls_by_uid (const void *pa
, const void *pb
)
1254 const numbered_tree
*nt_a
= ((const numbered_tree
*)pa
);
1255 const numbered_tree
*nt_b
= ((const numbered_tree
*)pb
);
1257 if (DECL_UID (nt_a
->t
) != DECL_UID (nt_b
->t
))
1258 return DECL_UID (nt_a
->t
) - DECL_UID (nt_b
->t
);
1259 return nt_a
->num
- nt_b
->num
;
1262 /* Called via walk_gimple_stmt / walk_gimple_op by dump_enumerated_decls. */
1264 dump_enumerated_decls_push (tree
*tp
, int *walk_subtrees
, void *data
)
1266 struct walk_stmt_info
*wi
= (struct walk_stmt_info
*) data
;
1267 VEC (numbered_tree
, heap
) **list
= (VEC (numbered_tree
, heap
) **) &wi
->info
;
1273 nt
.num
= VEC_length (numbered_tree
, *list
);
1274 VEC_safe_push (numbered_tree
, heap
, *list
, &nt
);
1279 /* Find all the declarations used by the current function, sort them by uid,
1280 and emit the sorted list. Each declaration is tagged with a sequence
1281 number indicating when it was found during statement / tree walking,
1282 so that TDF_NOUID comparisons of anonymous declarations are still
1283 meaningful. Where a declaration was encountered more than once, we
1284 emit only the sequence number of the first encounter.
1285 FILE is the dump file where to output the list and FLAGS is as in
1286 print_generic_expr. */
1288 dump_enumerated_decls (FILE *file
, int flags
)
1291 struct walk_stmt_info wi
;
1292 VEC (numbered_tree
, heap
) *decl_list
= VEC_alloc (numbered_tree
, heap
, 40);
1294 memset (&wi
, '\0', sizeof (wi
));
1295 wi
.info
= (void*) decl_list
;
1298 gimple_stmt_iterator gsi
;
1300 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1301 if (!is_gimple_debug (gsi_stmt (gsi
)))
1302 walk_gimple_stmt (&gsi
, NULL
, dump_enumerated_decls_push
, &wi
);
1304 decl_list
= (VEC (numbered_tree
, heap
) *) wi
.info
;
1305 VEC_qsort (numbered_tree
, decl_list
, compare_decls_by_uid
);
1306 if (VEC_length (numbered_tree
, decl_list
))
1310 tree last
= NULL_TREE
;
1312 fprintf (file
, "Declarations used by %s, sorted by DECL_UID:\n",
1313 current_function_name ());
1314 FOR_EACH_VEC_ELT (numbered_tree
, decl_list
, ix
, ntp
)
1318 fprintf (file
, "%d: ", ntp
->num
);
1319 print_generic_decl (file
, ntp
->t
, flags
);
1320 fprintf (file
, "\n");
1324 VEC_free (numbered_tree
, heap
, decl_list
);
1327 #ifdef ENABLE_CHECKING
1328 /* Verify that SSA_VAR is a non-virtual SSA_NAME. */
1331 register_ssa_partition_check (tree ssa_var
)
1333 gcc_assert (TREE_CODE (ssa_var
) == SSA_NAME
);
1334 if (!is_gimple_reg (SSA_NAME_VAR (ssa_var
)))
1336 fprintf (stderr
, "Illegally registering a virtual SSA name :");
1337 print_generic_expr (stderr
, ssa_var
, TDF_SLIM
);
1338 fprintf (stderr
, " in the SSA->Normal phase.\n");
1339 internal_error ("SSA corruption");
1344 /* Verify that the info in LIVE matches the current cfg. */
1347 verify_live_on_entry (tree_live_info_p live
)
1356 var_map map
= live
->map
;
1358 /* Check for live on entry partitions and report those with a DEF in
1359 the program. This will typically mean an optimization has done
1361 bb
= ENTRY_BLOCK_PTR
;
1363 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1365 int entry_block
= e
->dest
->index
;
1366 if (e
->dest
== EXIT_BLOCK_PTR
)
1368 for (i
= 0; i
< (unsigned)num_var_partitions (map
); i
++)
1373 var
= partition_to_var (map
, i
);
1374 stmt
= SSA_NAME_DEF_STMT (var
);
1375 tmp
= gimple_bb (stmt
);
1376 d
= gimple_default_def (cfun
, SSA_NAME_VAR (var
));
1378 loe
= live_on_entry (live
, e
->dest
);
1379 if (loe
&& bitmap_bit_p (loe
, i
))
1381 if (!gimple_nop_p (stmt
))
1384 print_generic_expr (stderr
, var
, TDF_SLIM
);
1385 fprintf (stderr
, " is defined ");
1387 fprintf (stderr
, " in BB%d, ", tmp
->index
);
1388 fprintf (stderr
, "by:\n");
1389 print_gimple_stmt (stderr
, stmt
, 0, TDF_SLIM
);
1390 fprintf (stderr
, "\nIt is also live-on-entry to entry BB %d",
1392 fprintf (stderr
, " So it appears to have multiple defs.\n");
1399 print_generic_expr (stderr
, var
, TDF_SLIM
);
1400 fprintf (stderr
, " is live-on-entry to BB%d ",
1404 fprintf (stderr
, " but is not the default def of ");
1405 print_generic_expr (stderr
, d
, TDF_SLIM
);
1406 fprintf (stderr
, "\n");
1409 fprintf (stderr
, " and there is no default def.\n");
1416 /* The only way this var shouldn't be marked live on entry is
1417 if it occurs in a PHI argument of the block. */
1420 gimple_stmt_iterator gsi
;
1421 for (gsi
= gsi_start_phis (e
->dest
);
1422 !gsi_end_p (gsi
) && !ok
;
1425 gimple phi
= gsi_stmt (gsi
);
1426 for (z
= 0; z
< gimple_phi_num_args (phi
); z
++)
1427 if (var
== gimple_phi_arg_def (phi
, z
))
1436 print_generic_expr (stderr
, var
, TDF_SLIM
);
1437 fprintf (stderr
, " is not marked live-on-entry to entry BB%d ",
1439 fprintf (stderr
, "but it is a default def so it should be.\n");
1443 gcc_assert (num
<= 0);