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
)
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 (var_ann (*t
) != NULL
&& is_used_p (*t
))
477 else if (TREE_CODE (*t
) == LABEL_DECL
&& TREE_USED (*t
))
478 /* For labels that are still used in the IL, the decision to
479 preserve them must not depend DEBUG_INFO_LEVEL, otherwise we
480 risk having different ordering in debug vs. non-debug builds
481 during inlining or versioning.
482 A label appearing here (we have already checked DECL_IGNORED_P)
483 should not be used in the IL unless it has been explicitly used
484 before, so we use TREE_USED as an approximation. */
485 /* In principle, we should do the same here as for the debug case
486 below, however, when debugging, there might be additional nested
487 levels that keep an upper level with a label live, so we have to
488 force this block to be considered used, too. */
491 /* When we are not doing full debug info, we however can keep around
492 only the used variables for cfgexpand's memory packing saving quite
495 For sake of -g3, we keep around those vars but we don't count this as
496 use of block, so innermost block with no used vars and no instructions
497 can be considered dead. We only want to keep around blocks user can
498 breakpoint into and ask about value of optimized out variables.
500 Similarly we need to keep around types at least until all
501 variables of all nested blocks are gone. We track no
502 information on whether given type is used or not, so we have
503 to keep them even when not emitting debug information,
504 otherwise we may end up remapping variables and their (local)
505 types in different orders depending on whether debug
506 information is being generated. */
508 else if (TREE_CODE (*t
) == TYPE_DECL
509 || debug_info_level
== DINFO_LEVEL_NORMAL
510 || debug_info_level
== DINFO_LEVEL_VERBOSE
)
514 *t
= DECL_CHAIN (*t
);
519 for (t
= &BLOCK_SUBBLOCKS (scope
); *t
;)
520 if (remove_unused_scope_block_p (*t
))
522 if (BLOCK_SUBBLOCKS (*t
))
524 tree next
= BLOCK_CHAIN (*t
);
525 tree supercontext
= BLOCK_SUPERCONTEXT (*t
);
527 *t
= BLOCK_SUBBLOCKS (*t
);
528 while (BLOCK_CHAIN (*t
))
530 BLOCK_SUPERCONTEXT (*t
) = supercontext
;
531 t
= &BLOCK_CHAIN (*t
);
533 BLOCK_CHAIN (*t
) = next
;
534 BLOCK_SUPERCONTEXT (*t
) = supercontext
;
535 t
= &BLOCK_CHAIN (*t
);
539 *t
= BLOCK_CHAIN (*t
);
543 t
= &BLOCK_CHAIN (*t
);
550 /* Outer scope is always used. */
551 else if (!BLOCK_SUPERCONTEXT (scope
)
552 || TREE_CODE (BLOCK_SUPERCONTEXT (scope
)) == FUNCTION_DECL
)
554 /* Innermost blocks with no live variables nor statements can be always
556 else if (!nsubblocks
)
558 /* For terse debug info we can eliminate info on unused variables. */
559 else if (debug_info_level
== DINFO_LEVEL_NONE
560 || debug_info_level
== DINFO_LEVEL_TERSE
)
562 /* Even for -g0/-g1 don't prune outer scopes from artificial
563 functions, otherwise diagnostics using tree_nonartificial_location
564 will not be emitted properly. */
565 if (inlined_function_outer_scope_p (scope
))
570 && TREE_CODE (ao
) == BLOCK
571 && BLOCK_ABSTRACT_ORIGIN (ao
) != ao
)
572 ao
= BLOCK_ABSTRACT_ORIGIN (ao
);
574 && TREE_CODE (ao
) == FUNCTION_DECL
575 && DECL_DECLARED_INLINE_P (ao
)
576 && lookup_attribute ("artificial", DECL_ATTRIBUTES (ao
)))
580 else if (BLOCK_VARS (scope
) || BLOCK_NUM_NONLOCALIZED_VARS (scope
))
582 /* See if this block is important for representation of inlined function.
583 Inlined functions are always represented by block with
584 block_ultimate_origin being set to FUNCTION_DECL and DECL_SOURCE_LOCATION
586 else if (inlined_function_outer_scope_p (scope
))
589 /* Verfify that only blocks with source location set
590 are entry points to the inlined functions. */
591 gcc_assert (BLOCK_SOURCE_LOCATION (scope
) == UNKNOWN_LOCATION
);
593 TREE_USED (scope
) = !unused
;
597 /* Mark all VAR_DECLS under *EXPR_P as used, so that they won't be
598 eliminated during the tree->rtl conversion process. */
601 mark_all_vars_used (tree
*expr_p
, void *data
)
603 walk_tree (expr_p
, mark_all_vars_used_1
, data
, NULL
);
607 /* Dump scope blocks starting at SCOPE to FILE. INDENT is the
608 indentation level and FLAGS is as in print_generic_expr. */
611 dump_scope_block (FILE *file
, int indent
, tree scope
, int flags
)
616 fprintf (file
, "\n%*s{ Scope block #%i%s%s",indent
, "" , BLOCK_NUMBER (scope
),
617 TREE_USED (scope
) ? "" : " (unused)",
618 BLOCK_ABSTRACT (scope
) ? " (abstract)": "");
619 if (BLOCK_SOURCE_LOCATION (scope
) != UNKNOWN_LOCATION
)
621 expanded_location s
= expand_location (BLOCK_SOURCE_LOCATION (scope
));
622 fprintf (file
, " %s:%i", s
.file
, s
.line
);
624 if (BLOCK_ABSTRACT_ORIGIN (scope
))
626 tree origin
= block_ultimate_origin (scope
);
629 fprintf (file
, " Originating from :");
631 print_generic_decl (file
, origin
, flags
);
633 fprintf (file
, "#%i", BLOCK_NUMBER (origin
));
636 fprintf (file
, " \n");
637 for (var
= BLOCK_VARS (scope
); var
; var
= DECL_CHAIN (var
))
642 used
= is_used_p (var
);
644 fprintf (file
, "%*s", indent
, "");
645 print_generic_decl (file
, var
, flags
);
646 fprintf (file
, "%s\n", used
? "" : " (unused)");
648 for (i
= 0; i
< BLOCK_NUM_NONLOCALIZED_VARS (scope
); i
++)
650 fprintf (file
, "%*s",indent
, "");
651 print_generic_decl (file
, BLOCK_NONLOCALIZED_VAR (scope
, i
),
653 fprintf (file
, " (nonlocalized)\n");
655 for (t
= BLOCK_SUBBLOCKS (scope
); t
; t
= BLOCK_CHAIN (t
))
656 dump_scope_block (file
, indent
+ 2, t
, flags
);
657 fprintf (file
, "\n%*s}\n",indent
, "");
660 /* Dump the tree of lexical scopes starting at SCOPE to stderr. FLAGS
661 is as in print_generic_expr. */
664 debug_scope_block (tree scope
, int flags
)
666 dump_scope_block (stderr
, 0, scope
, flags
);
670 /* Dump the tree of lexical scopes of current_function_decl to FILE.
671 FLAGS is as in print_generic_expr. */
674 dump_scope_blocks (FILE *file
, int flags
)
676 dump_scope_block (file
, 0, DECL_INITIAL (current_function_decl
), flags
);
680 /* Dump the tree of lexical scopes of current_function_decl to stderr.
681 FLAGS is as in print_generic_expr. */
684 debug_scope_blocks (int flags
)
686 dump_scope_blocks (stderr
, flags
);
689 /* Remove local variables that are not referenced in the IL. */
692 remove_unused_locals (void)
696 referenced_var_iterator rvi
;
697 bitmap global_unused_vars
= NULL
;
698 unsigned srcidx
, dstidx
, num
, ix
;
699 bool have_local_clobbers
= false;
701 /* Removing declarations from lexical blocks when not optimizing is
702 not only a waste of time, it actually causes differences in stack
707 timevar_push (TV_REMOVE_UNUSED
);
709 mark_scope_block_unused (DECL_INITIAL (current_function_decl
));
711 /* Assume all locals are unused. */
712 FOR_EACH_REFERENCED_VAR (cfun
, t
, rvi
)
715 /* Assume all globals in local decls are unused. */
716 global_unused_vars
= BITMAP_ALLOC (NULL
);
717 FOR_EACH_LOCAL_DECL (cfun
, ix
, var
)
718 if (TREE_CODE (var
) == VAR_DECL
719 && is_global_var (var
))
720 bitmap_set_bit (global_unused_vars
, DECL_UID (var
));
722 /* Walk the CFG marking all referenced symbols. */
725 gimple_stmt_iterator gsi
;
730 /* Walk the statements. */
731 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
733 gimple stmt
= gsi_stmt (gsi
);
734 tree b
= gimple_block (stmt
);
736 if (is_gimple_debug (stmt
))
739 if (gimple_clobber_p (stmt
))
741 have_local_clobbers
= true;
746 TREE_USED (b
) = true;
748 for (i
= 0; i
< gimple_num_ops (stmt
); i
++)
749 mark_all_vars_used (gimple_op_ptr (gsi_stmt (gsi
), i
),
753 for (gsi
= gsi_start_phis (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
758 gimple phi
= gsi_stmt (gsi
);
760 if (!is_gimple_reg (gimple_phi_result (phi
)))
763 def
= gimple_phi_result (phi
);
764 mark_all_vars_used (&def
, global_unused_vars
);
766 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_ALL_USES
)
768 tree arg
= USE_FROM_PTR (arg_p
);
769 mark_all_vars_used (&arg
, global_unused_vars
);
773 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
775 TREE_USED (e
->goto_block
) = true;
778 /* We do a two-pass approach about the out-of-scope clobbers. We want
779 to remove them if they are the only references to a local variable,
780 but we want to retain them when there's any other. So the first pass
781 ignores them, and the second pass (if there were any) tries to remove
783 if (have_local_clobbers
)
786 gimple_stmt_iterator gsi
;
788 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
);)
790 gimple stmt
= gsi_stmt (gsi
);
791 tree b
= gimple_block (stmt
);
793 if (gimple_clobber_p (stmt
))
795 tree lhs
= gimple_assign_lhs (stmt
);
796 lhs
= get_base_address (lhs
);
797 if (TREE_CODE (lhs
) == SSA_NAME
)
798 lhs
= SSA_NAME_VAR (lhs
);
799 if (TREE_CODE (lhs
) == VAR_DECL
800 && ((is_global_var (lhs
)
801 && bitmap_bit_p (global_unused_vars
, DECL_UID (lhs
)))
802 || (!is_global_var (lhs
) && !is_used_p (lhs
))))
804 unlink_stmt_vdef (stmt
);
805 gsi_remove (&gsi
, true);
810 TREE_USED (b
) = true;
816 cfun
->has_local_explicit_reg_vars
= false;
818 /* Remove unmarked local and global vars from local_decls
819 and referenced vars. */
820 num
= VEC_length (tree
, cfun
->local_decls
);
821 for (srcidx
= 0, dstidx
= 0; srcidx
< num
; srcidx
++)
823 var
= VEC_index (tree
, cfun
->local_decls
, srcidx
);
824 if (TREE_CODE (var
) == VAR_DECL
)
826 if (is_global_var (var
))
828 if (bitmap_bit_p (global_unused_vars
, DECL_UID (var
)))
831 else if (var_ann (var
) == NULL
835 remove_referenced_var (var
);
839 if (TREE_CODE (var
) == VAR_DECL
840 && DECL_HARD_REGISTER (var
)
841 && !is_global_var (var
))
842 cfun
->has_local_explicit_reg_vars
= true;
844 if (srcidx
!= dstidx
)
845 VEC_replace (tree
, cfun
->local_decls
, dstidx
, var
);
849 VEC_truncate (tree
, cfun
->local_decls
, dstidx
);
850 BITMAP_FREE (global_unused_vars
);
852 remove_unused_scope_block_p (DECL_INITIAL (current_function_decl
));
853 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
855 fprintf (dump_file
, "Scope blocks after cleanups:\n");
856 dump_scope_blocks (dump_file
, dump_flags
);
859 timevar_pop (TV_REMOVE_UNUSED
);
863 /* Allocate and return a new live range information object base on MAP. */
865 static tree_live_info_p
866 new_tree_live_info (var_map map
)
868 tree_live_info_p live
;
871 live
= (tree_live_info_p
) xmalloc (sizeof (struct tree_live_info_d
));
873 live
->num_blocks
= last_basic_block
;
875 live
->livein
= (bitmap
*)xmalloc (last_basic_block
* sizeof (bitmap
));
876 for (x
= 0; x
< (unsigned)last_basic_block
; x
++)
877 live
->livein
[x
] = BITMAP_ALLOC (NULL
);
879 live
->liveout
= (bitmap
*)xmalloc (last_basic_block
* sizeof (bitmap
));
880 for (x
= 0; x
< (unsigned)last_basic_block
; x
++)
881 live
->liveout
[x
] = BITMAP_ALLOC (NULL
);
883 live
->work_stack
= XNEWVEC (int, last_basic_block
);
884 live
->stack_top
= live
->work_stack
;
886 live
->global
= BITMAP_ALLOC (NULL
);
891 /* Free storage for live range info object LIVE. */
894 delete_tree_live_info (tree_live_info_p live
)
898 BITMAP_FREE (live
->global
);
899 free (live
->work_stack
);
901 for (x
= live
->num_blocks
- 1; x
>= 0; x
--)
902 BITMAP_FREE (live
->liveout
[x
]);
903 free (live
->liveout
);
905 for (x
= live
->num_blocks
- 1; x
>= 0; x
--)
906 BITMAP_FREE (live
->livein
[x
]);
913 /* Visit basic block BB and propagate any required live on entry bits from
914 LIVE into the predecessors. VISITED is the bitmap of visited blocks.
915 TMP is a temporary work bitmap which is passed in to avoid reallocating
919 loe_visit_block (tree_live_info_p live
, basic_block bb
, sbitmap visited
,
927 gcc_assert (!TEST_BIT (visited
, bb
->index
));
929 SET_BIT (visited
, bb
->index
);
930 loe
= live_on_entry (live
, bb
);
932 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
935 if (pred_bb
== ENTRY_BLOCK_PTR
)
937 /* TMP is variables live-on-entry from BB that aren't defined in the
938 predecessor block. This should be the live on entry vars to pred.
939 Note that liveout is the DEFs in a block while live on entry is
941 bitmap_and_compl (tmp
, loe
, live
->liveout
[pred_bb
->index
]);
943 /* Add these bits to live-on-entry for the pred. if there are any
944 changes, and pred_bb has been visited already, add it to the
946 change
= bitmap_ior_into (live_on_entry (live
, pred_bb
), tmp
);
947 if (TEST_BIT (visited
, pred_bb
->index
) && change
)
949 RESET_BIT (visited
, pred_bb
->index
);
950 *(live
->stack_top
)++ = pred_bb
->index
;
956 /* Using LIVE, fill in all the live-on-entry blocks between the defs and uses
957 of all the variables. */
960 live_worklist (tree_live_info_p live
)
964 sbitmap visited
= sbitmap_alloc (last_basic_block
+ 1);
965 bitmap tmp
= BITMAP_ALLOC (NULL
);
967 sbitmap_zero (visited
);
969 /* Visit all the blocks in reverse order and propagate live on entry values
970 into the predecessors blocks. */
971 FOR_EACH_BB_REVERSE (bb
)
972 loe_visit_block (live
, bb
, visited
, tmp
);
974 /* Process any blocks which require further iteration. */
975 while (live
->stack_top
!= live
->work_stack
)
977 b
= *--(live
->stack_top
);
978 loe_visit_block (live
, BASIC_BLOCK (b
), visited
, tmp
);
982 sbitmap_free (visited
);
986 /* Calculate the initial live on entry vector for SSA_NAME using immediate_use
987 links. Set the live on entry fields in LIVE. Def's are marked temporarily
988 in the liveout vector. */
991 set_var_live_on_entry (tree ssa_name
, tree_live_info_p live
)
996 basic_block def_bb
= NULL
;
997 imm_use_iterator imm_iter
;
1000 p
= var_to_partition (live
->map
, ssa_name
);
1001 if (p
== NO_PARTITION
)
1004 stmt
= SSA_NAME_DEF_STMT (ssa_name
);
1007 def_bb
= gimple_bb (stmt
);
1008 /* Mark defs in liveout bitmap temporarily. */
1010 bitmap_set_bit (live
->liveout
[def_bb
->index
], p
);
1013 def_bb
= ENTRY_BLOCK_PTR
;
1015 /* Visit each use of SSA_NAME and if it isn't in the same block as the def,
1016 add it to the list of live on entry blocks. */
1017 FOR_EACH_IMM_USE_FAST (use
, imm_iter
, ssa_name
)
1019 gimple use_stmt
= USE_STMT (use
);
1020 basic_block add_block
= NULL
;
1022 if (gimple_code (use_stmt
) == GIMPLE_PHI
)
1024 /* Uses in PHI's are considered to be live at exit of the SRC block
1025 as this is where a copy would be inserted. Check to see if it is
1026 defined in that block, or whether its live on entry. */
1027 int index
= PHI_ARG_INDEX_FROM_USE (use
);
1028 edge e
= gimple_phi_arg_edge (use_stmt
, index
);
1029 if (e
->src
!= ENTRY_BLOCK_PTR
)
1031 if (e
->src
!= def_bb
)
1035 else if (is_gimple_debug (use_stmt
))
1039 /* If its not defined in this block, its live on entry. */
1040 basic_block use_bb
= gimple_bb (use_stmt
);
1041 if (use_bb
!= def_bb
)
1045 /* If there was a live on entry use, set the bit. */
1049 bitmap_set_bit (live
->livein
[add_block
->index
], p
);
1053 /* If SSA_NAME is live on entry to at least one block, fill in all the live
1054 on entry blocks between the def and all the uses. */
1056 bitmap_set_bit (live
->global
, p
);
1060 /* Calculate the live on exit vectors based on the entry info in LIVEINFO. */
1063 calculate_live_on_exit (tree_live_info_p liveinfo
)
1069 /* live on entry calculations used liveout vectors for defs, clear them. */
1071 bitmap_clear (liveinfo
->liveout
[bb
->index
]);
1073 /* Set all the live-on-exit bits for uses in PHIs. */
1076 gimple_stmt_iterator gsi
;
1079 /* Mark the PHI arguments which are live on exit to the pred block. */
1080 for (gsi
= gsi_start_phis (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1082 gimple phi
= gsi_stmt (gsi
);
1083 for (i
= 0; i
< gimple_phi_num_args (phi
); i
++)
1085 tree t
= PHI_ARG_DEF (phi
, i
);
1088 if (TREE_CODE (t
) != SSA_NAME
)
1091 p
= var_to_partition (liveinfo
->map
, t
);
1092 if (p
== NO_PARTITION
)
1094 e
= gimple_phi_arg_edge (phi
, i
);
1095 if (e
->src
!= ENTRY_BLOCK_PTR
)
1096 bitmap_set_bit (liveinfo
->liveout
[e
->src
->index
], p
);
1100 /* Add each successors live on entry to this bock live on exit. */
1101 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1102 if (e
->dest
!= EXIT_BLOCK_PTR
)
1103 bitmap_ior_into (liveinfo
->liveout
[bb
->index
],
1104 live_on_entry (liveinfo
, e
->dest
));
1109 /* Given partition map MAP, calculate all the live on entry bitmaps for
1110 each partition. Return a new live info object. */
1113 calculate_live_ranges (var_map map
)
1117 tree_live_info_p live
;
1119 live
= new_tree_live_info (map
);
1120 for (i
= 0; i
< num_var_partitions (map
); i
++)
1122 var
= partition_to_var (map
, i
);
1123 if (var
!= NULL_TREE
)
1124 set_var_live_on_entry (var
, live
);
1127 live_worklist (live
);
1129 #ifdef ENABLE_CHECKING
1130 verify_live_on_entry (live
);
1133 calculate_live_on_exit (live
);
1138 /* Output partition map MAP to file F. */
1141 dump_var_map (FILE *f
, var_map map
)
1147 fprintf (f
, "\nPartition map \n\n");
1149 for (x
= 0; x
< map
->num_partitions
; x
++)
1151 if (map
->view_to_partition
!= NULL
)
1152 p
= map
->view_to_partition
[x
];
1156 if (ssa_name (p
) == NULL_TREE
)
1160 for (y
= 1; y
< num_ssa_names
; y
++)
1162 p
= partition_find (map
->var_partition
, y
);
1163 if (map
->partition_to_view
)
1164 p
= map
->partition_to_view
[p
];
1169 fprintf(f
, "Partition %d (", x
);
1170 print_generic_expr (f
, partition_to_var (map
, p
), TDF_SLIM
);
1173 fprintf (f
, "%d ", y
);
1183 /* Output live range info LIVE to file F, controlled by FLAG. */
1186 dump_live_info (FILE *f
, tree_live_info_p live
, int flag
)
1190 var_map map
= live
->map
;
1193 if ((flag
& LIVEDUMP_ENTRY
) && live
->livein
)
1197 fprintf (f
, "\nLive on entry to BB%d : ", bb
->index
);
1198 EXECUTE_IF_SET_IN_BITMAP (live
->livein
[bb
->index
], 0, i
, bi
)
1200 print_generic_expr (f
, partition_to_var (map
, i
), TDF_SLIM
);
1207 if ((flag
& LIVEDUMP_EXIT
) && live
->liveout
)
1211 fprintf (f
, "\nLive on exit from BB%d : ", bb
->index
);
1212 EXECUTE_IF_SET_IN_BITMAP (live
->liveout
[bb
->index
], 0, i
, bi
)
1214 print_generic_expr (f
, partition_to_var (map
, i
), TDF_SLIM
);
1222 struct GTY(()) numbered_tree_d
1227 typedef struct numbered_tree_d numbered_tree
;
1229 DEF_VEC_O (numbered_tree
);
1230 DEF_VEC_ALLOC_O (numbered_tree
, heap
);
1232 /* Compare two declarations references by their DECL_UID / sequence number.
1233 Called via qsort. */
1236 compare_decls_by_uid (const void *pa
, const void *pb
)
1238 const numbered_tree
*nt_a
= ((const numbered_tree
*)pa
);
1239 const numbered_tree
*nt_b
= ((const numbered_tree
*)pb
);
1241 if (DECL_UID (nt_a
->t
) != DECL_UID (nt_b
->t
))
1242 return DECL_UID (nt_a
->t
) - DECL_UID (nt_b
->t
);
1243 return nt_a
->num
- nt_b
->num
;
1246 /* Called via walk_gimple_stmt / walk_gimple_op by dump_enumerated_decls. */
1248 dump_enumerated_decls_push (tree
*tp
, int *walk_subtrees
, void *data
)
1250 struct walk_stmt_info
*wi
= (struct walk_stmt_info
*) data
;
1251 VEC (numbered_tree
, heap
) **list
= (VEC (numbered_tree
, heap
) **) &wi
->info
;
1257 nt
.num
= VEC_length (numbered_tree
, *list
);
1258 VEC_safe_push (numbered_tree
, heap
, *list
, &nt
);
1263 /* Find all the declarations used by the current function, sort them by uid,
1264 and emit the sorted list. Each declaration is tagged with a sequence
1265 number indicating when it was found during statement / tree walking,
1266 so that TDF_NOUID comparisons of anonymous declarations are still
1267 meaningful. Where a declaration was encountered more than once, we
1268 emit only the sequence number of the first encounter.
1269 FILE is the dump file where to output the list and FLAGS is as in
1270 print_generic_expr. */
1272 dump_enumerated_decls (FILE *file
, int flags
)
1275 struct walk_stmt_info wi
;
1276 VEC (numbered_tree
, heap
) *decl_list
= VEC_alloc (numbered_tree
, heap
, 40);
1278 memset (&wi
, '\0', sizeof (wi
));
1279 wi
.info
= (void*) decl_list
;
1282 gimple_stmt_iterator gsi
;
1284 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1285 if (!is_gimple_debug (gsi_stmt (gsi
)))
1286 walk_gimple_stmt (&gsi
, NULL
, dump_enumerated_decls_push
, &wi
);
1288 decl_list
= (VEC (numbered_tree
, heap
) *) wi
.info
;
1289 VEC_qsort (numbered_tree
, decl_list
, compare_decls_by_uid
);
1290 if (VEC_length (numbered_tree
, decl_list
))
1294 tree last
= NULL_TREE
;
1296 fprintf (file
, "Declarations used by %s, sorted by DECL_UID:\n",
1297 current_function_name ());
1298 FOR_EACH_VEC_ELT (numbered_tree
, decl_list
, ix
, ntp
)
1302 fprintf (file
, "%d: ", ntp
->num
);
1303 print_generic_decl (file
, ntp
->t
, flags
);
1304 fprintf (file
, "\n");
1308 VEC_free (numbered_tree
, heap
, decl_list
);
1311 #ifdef ENABLE_CHECKING
1312 /* Verify that SSA_VAR is a non-virtual SSA_NAME. */
1315 register_ssa_partition_check (tree ssa_var
)
1317 gcc_assert (TREE_CODE (ssa_var
) == SSA_NAME
);
1318 if (!is_gimple_reg (SSA_NAME_VAR (ssa_var
)))
1320 fprintf (stderr
, "Illegally registering a virtual SSA name :");
1321 print_generic_expr (stderr
, ssa_var
, TDF_SLIM
);
1322 fprintf (stderr
, " in the SSA->Normal phase.\n");
1323 internal_error ("SSA corruption");
1328 /* Verify that the info in LIVE matches the current cfg. */
1331 verify_live_on_entry (tree_live_info_p live
)
1340 var_map map
= live
->map
;
1342 /* Check for live on entry partitions and report those with a DEF in
1343 the program. This will typically mean an optimization has done
1345 bb
= ENTRY_BLOCK_PTR
;
1347 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1349 int entry_block
= e
->dest
->index
;
1350 if (e
->dest
== EXIT_BLOCK_PTR
)
1352 for (i
= 0; i
< (unsigned)num_var_partitions (map
); i
++)
1357 var
= partition_to_var (map
, i
);
1358 stmt
= SSA_NAME_DEF_STMT (var
);
1359 tmp
= gimple_bb (stmt
);
1360 d
= gimple_default_def (cfun
, SSA_NAME_VAR (var
));
1362 loe
= live_on_entry (live
, e
->dest
);
1363 if (loe
&& bitmap_bit_p (loe
, i
))
1365 if (!gimple_nop_p (stmt
))
1368 print_generic_expr (stderr
, var
, TDF_SLIM
);
1369 fprintf (stderr
, " is defined ");
1371 fprintf (stderr
, " in BB%d, ", tmp
->index
);
1372 fprintf (stderr
, "by:\n");
1373 print_gimple_stmt (stderr
, stmt
, 0, TDF_SLIM
);
1374 fprintf (stderr
, "\nIt is also live-on-entry to entry BB %d",
1376 fprintf (stderr
, " So it appears to have multiple defs.\n");
1383 print_generic_expr (stderr
, var
, TDF_SLIM
);
1384 fprintf (stderr
, " is live-on-entry to BB%d ",
1388 fprintf (stderr
, " but is not the default def of ");
1389 print_generic_expr (stderr
, d
, TDF_SLIM
);
1390 fprintf (stderr
, "\n");
1393 fprintf (stderr
, " and there is no default def.\n");
1400 /* The only way this var shouldn't be marked live on entry is
1401 if it occurs in a PHI argument of the block. */
1404 gimple_stmt_iterator gsi
;
1405 for (gsi
= gsi_start_phis (e
->dest
);
1406 !gsi_end_p (gsi
) && !ok
;
1409 gimple phi
= gsi_stmt (gsi
);
1410 for (z
= 0; z
< gimple_phi_num_args (phi
); z
++)
1411 if (var
== gimple_phi_arg_def (phi
, z
))
1420 print_generic_expr (stderr
, var
, TDF_SLIM
);
1421 fprintf (stderr
, " is not marked live-on-entry to entry BB%d ",
1423 fprintf (stderr
, "but it is a default def so it should be.\n");
1427 gcc_assert (num
<= 0);