1 /* Liveness for SSA trees.
2 Copyright (C) 2003-2013 Free Software Foundation, Inc.
3 Contributed by Andrew MacLeod <amacleod@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
26 #include "gimple-pretty-print.h"
28 #include "tree-flow.h"
31 #include "tree-ssa-live.h"
32 #include "diagnostic-core.h"
37 #ifdef ENABLE_CHECKING
38 static void verify_live_on_entry (tree_live_info_p
);
42 /* VARMAP maintains a mapping from SSA version number to real variables.
44 All SSA_NAMES are divided into partitions. Initially each ssa_name is the
45 only member of it's own partition. Coalescing will attempt to group any
46 ssa_names which occur in a copy or in a PHI node into the same partition.
48 At the end of out-of-ssa, each partition becomes a "real" variable and is
49 rewritten as a compiler variable.
51 The var_map data structure is used to manage these partitions. It allows
52 partitions to be combined, and determines which partition belongs to what
53 ssa_name or variable, and vice versa. */
56 /* This routine will initialize the basevar fields of MAP. */
59 var_map_base_init (var_map map
)
64 struct tree_int_map
*m
, *mapstorage
;
66 num_part
= num_var_partitions (map
);
67 tree_to_index
= htab_create (num_part
, tree_map_base_hash
,
68 tree_int_map_eq
, NULL
);
69 /* We can have at most num_part entries in the hash tables, so it's
70 enough to allocate so many map elements once, saving some malloc
72 mapstorage
= m
= XNEWVEC (struct tree_int_map
, num_part
);
74 /* If a base table already exists, clear it, otherwise create it. */
75 free (map
->partition_to_base_index
);
76 map
->partition_to_base_index
= (int *) xmalloc (sizeof (int) * num_part
);
78 /* Build the base variable list, and point partitions at their bases. */
79 for (x
= 0; x
< num_part
; x
++)
81 struct tree_int_map
**slot
;
83 var
= partition_to_var (map
, x
);
84 if (SSA_NAME_VAR (var
))
85 m
->base
.from
= SSA_NAME_VAR (var
);
87 /* This restricts what anonymous SSA names we can coalesce
88 as it restricts the sets we compute conflicts for.
89 Using TREE_TYPE to generate sets is the easies as
90 type equivalency also holds for SSA names with the same
92 m
->base
.from
= TREE_TYPE (var
);
93 /* If base variable hasn't been seen, set it up. */
94 slot
= (struct tree_int_map
**) htab_find_slot (tree_to_index
,
98 baseindex
= m
- mapstorage
;
104 baseindex
= (*slot
)->to
;
105 map
->partition_to_base_index
[x
] = baseindex
;
108 map
->num_basevars
= m
- mapstorage
;
111 htab_delete (tree_to_index
);
115 /* Remove the base table in MAP. */
118 var_map_base_fini (var_map map
)
120 /* Free the basevar info if it is present. */
121 if (map
->partition_to_base_index
!= NULL
)
123 free (map
->partition_to_base_index
);
124 map
->partition_to_base_index
= NULL
;
125 map
->num_basevars
= 0;
128 /* Create a variable partition map of SIZE, initialize and return it. */
131 init_var_map (int size
)
135 map
= (var_map
) xmalloc (sizeof (struct _var_map
));
136 map
->var_partition
= partition_new (size
);
138 map
->partition_to_view
= NULL
;
139 map
->view_to_partition
= NULL
;
140 map
->num_partitions
= size
;
141 map
->partition_size
= size
;
142 map
->num_basevars
= 0;
143 map
->partition_to_base_index
= NULL
;
148 /* Free memory associated with MAP. */
151 delete_var_map (var_map map
)
153 var_map_base_fini (map
);
154 partition_delete (map
->var_partition
);
155 free (map
->partition_to_view
);
156 free (map
->view_to_partition
);
161 /* This function will combine the partitions in MAP for VAR1 and VAR2. It
162 Returns the partition which represents the new partition. If the two
163 partitions cannot be combined, NO_PARTITION is returned. */
166 var_union (var_map map
, tree var1
, tree var2
)
170 gcc_assert (TREE_CODE (var1
) == SSA_NAME
);
171 gcc_assert (TREE_CODE (var2
) == SSA_NAME
);
173 /* This is independent of partition_to_view. If partition_to_view is
174 on, then whichever one of these partitions is absorbed will never have a
175 dereference into the partition_to_view array any more. */
177 p1
= partition_find (map
->var_partition
, SSA_NAME_VERSION (var1
));
178 p2
= partition_find (map
->var_partition
, SSA_NAME_VERSION (var2
));
180 gcc_assert (p1
!= NO_PARTITION
);
181 gcc_assert (p2
!= NO_PARTITION
);
186 p3
= partition_union (map
->var_partition
, p1
, p2
);
188 if (map
->partition_to_view
)
189 p3
= map
->partition_to_view
[p3
];
195 /* Compress the partition numbers in MAP such that they fall in the range
196 0..(num_partitions-1) instead of wherever they turned out during
197 the partitioning exercise. This removes any references to unused
198 partitions, thereby allowing bitmaps and other vectors to be much
201 This is implemented such that compaction doesn't affect partitioning.
202 Ie., once partitions are created and possibly merged, running one
203 or more different kind of compaction will not affect the partitions
204 themselves. Their index might change, but all the same variables will
205 still be members of the same partition group. This allows work on reduced
206 sets, and no loss of information when a larger set is later desired.
208 In particular, coalescing can work on partitions which have 2 or more
209 definitions, and then 'recompact' later to include all the single
210 definitions for assignment to program variables. */
213 /* Set MAP back to the initial state of having no partition view. Return a
214 bitmap which has a bit set for each partition number which is in use in the
218 partition_view_init (var_map map
)
224 used
= BITMAP_ALLOC (NULL
);
226 /* Already in a view? Abandon the old one. */
227 if (map
->partition_to_view
)
229 free (map
->partition_to_view
);
230 map
->partition_to_view
= NULL
;
232 if (map
->view_to_partition
)
234 free (map
->view_to_partition
);
235 map
->view_to_partition
= NULL
;
238 /* Find out which partitions are actually referenced. */
239 for (x
= 0; x
< map
->partition_size
; x
++)
241 tmp
= partition_find (map
->var_partition
, x
);
242 if (ssa_name (tmp
) != NULL_TREE
&& !virtual_operand_p (ssa_name (tmp
))
243 && (!has_zero_uses (ssa_name (tmp
))
244 || !SSA_NAME_IS_DEFAULT_DEF (ssa_name (tmp
))))
245 bitmap_set_bit (used
, tmp
);
248 map
->num_partitions
= map
->partition_size
;
253 /* This routine will finalize the view data for MAP based on the partitions
254 set in SELECTED. This is either the same bitmap returned from
255 partition_view_init, or a trimmed down version if some of those partitions
256 were not desired in this view. SELECTED is freed before returning. */
259 partition_view_fini (var_map map
, bitmap selected
)
262 unsigned count
, i
, x
, limit
;
264 gcc_assert (selected
);
266 count
= bitmap_count_bits (selected
);
267 limit
= map
->partition_size
;
269 /* If its a one-to-one ratio, we don't need any view compaction. */
272 map
->partition_to_view
= (int *)xmalloc (limit
* sizeof (int));
273 memset (map
->partition_to_view
, 0xff, (limit
* sizeof (int)));
274 map
->view_to_partition
= (int *)xmalloc (count
* sizeof (int));
277 /* Give each selected partition an index. */
278 EXECUTE_IF_SET_IN_BITMAP (selected
, 0, x
, bi
)
280 map
->partition_to_view
[x
] = i
;
281 map
->view_to_partition
[i
] = x
;
284 gcc_assert (i
== count
);
285 map
->num_partitions
= i
;
288 BITMAP_FREE (selected
);
292 /* Create a partition view which includes all the used partitions in MAP. If
293 WANT_BASES is true, create the base variable map as well. */
296 partition_view_normal (var_map map
, bool want_bases
)
300 used
= partition_view_init (map
);
301 partition_view_fini (map
, used
);
304 var_map_base_init (map
);
306 var_map_base_fini (map
);
310 /* Create a partition view in MAP which includes just partitions which occur in
311 the bitmap ONLY. If WANT_BASES is true, create the base variable map
315 partition_view_bitmap (var_map map
, bitmap only
, bool want_bases
)
318 bitmap new_partitions
= BITMAP_ALLOC (NULL
);
322 used
= partition_view_init (map
);
323 EXECUTE_IF_SET_IN_BITMAP (only
, 0, x
, bi
)
325 p
= partition_find (map
->var_partition
, x
);
326 gcc_assert (bitmap_bit_p (used
, p
));
327 bitmap_set_bit (new_partitions
, p
);
329 partition_view_fini (map
, new_partitions
);
332 var_map_base_init (map
);
334 var_map_base_fini (map
);
338 static bitmap usedvars
;
340 /* Mark VAR as used, so that it'll be preserved during rtl expansion.
341 Returns true if VAR wasn't marked before. */
344 set_is_used (tree var
)
346 return bitmap_set_bit (usedvars
, DECL_UID (var
));
349 /* Return true if VAR is marked as used. */
354 return bitmap_bit_p (usedvars
, DECL_UID (var
));
357 static inline void mark_all_vars_used (tree
*);
359 /* Helper function for mark_all_vars_used, called via walk_tree. */
362 mark_all_vars_used_1 (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
365 enum tree_code_class c
= TREE_CODE_CLASS (TREE_CODE (t
));
368 if (TREE_CODE (t
) == SSA_NAME
)
371 t
= SSA_NAME_VAR (t
);
376 if (IS_EXPR_CODE_CLASS (c
)
377 && (b
= TREE_BLOCK (t
)) != NULL
)
378 TREE_USED (b
) = true;
380 /* Ignore TMR_OFFSET and TMR_STEP for TARGET_MEM_REFS, as those
381 fields do not contain vars. */
382 if (TREE_CODE (t
) == TARGET_MEM_REF
)
384 mark_all_vars_used (&TMR_BASE (t
));
385 mark_all_vars_used (&TMR_INDEX (t
));
386 mark_all_vars_used (&TMR_INDEX2 (t
));
391 /* Only need to mark VAR_DECLS; parameters and return results are not
392 eliminated as unused. */
393 if (TREE_CODE (t
) == VAR_DECL
)
395 /* When a global var becomes used for the first time also walk its
396 initializer (non global ones don't have any). */
397 if (set_is_used (t
) && is_global_var (t
))
398 mark_all_vars_used (&DECL_INITIAL (t
));
400 /* remove_unused_scope_block_p requires information about labels
401 which are not DECL_IGNORED_P to tell if they might be used in the IL. */
402 else if (TREE_CODE (t
) == LABEL_DECL
)
403 /* Although the TREE_USED values that the frontend uses would be
404 acceptable (albeit slightly over-conservative) for our purposes,
405 init_vars_expansion clears TREE_USED for LABEL_DECLs too, so we
406 must re-compute it here. */
409 if (IS_TYPE_OR_DECL_P (t
))
415 /* Mark the scope block SCOPE and its subblocks unused when they can be
416 possibly eliminated if dead. */
419 mark_scope_block_unused (tree scope
)
422 TREE_USED (scope
) = false;
423 if (!(*debug_hooks
->ignore_block
) (scope
))
424 TREE_USED (scope
) = true;
425 for (t
= BLOCK_SUBBLOCKS (scope
); t
; t
= BLOCK_CHAIN (t
))
426 mark_scope_block_unused (t
);
429 /* Look if the block is dead (by possibly eliminating its dead subblocks)
430 and return true if so.
431 Block is declared dead if:
432 1) No statements are associated with it.
433 2) Declares no live variables
434 3) All subblocks are dead
435 or there is precisely one subblocks and the block
436 has same abstract origin as outer block and declares
437 no variables, so it is pure wrapper.
438 When we are not outputting full debug info, we also eliminate dead variables
439 out of scope blocks to let them to be recycled by GGC and to save copying work
440 done by the inliner. */
443 remove_unused_scope_block_p (tree scope
)
446 bool unused
= !TREE_USED (scope
);
449 for (t
= &BLOCK_VARS (scope
); *t
; t
= next
)
451 next
= &DECL_CHAIN (*t
);
453 /* Debug info of nested function refers to the block of the
454 function. We might stil call it even if all statements
455 of function it was nested into was elliminated.
457 TODO: We can actually look into cgraph to see if function
458 will be output to file. */
459 if (TREE_CODE (*t
) == FUNCTION_DECL
)
462 /* If a decl has a value expr, we need to instantiate it
463 regardless of debug info generation, to avoid codegen
464 differences in memory overlap tests. update_equiv_regs() may
465 indirectly call validate_equiv_mem() to test whether a
466 SET_DEST overlaps with others, and if the value expr changes
467 by virtual register instantiation, we may get end up with
468 different results. */
469 else if (TREE_CODE (*t
) == VAR_DECL
&& DECL_HAS_VALUE_EXPR_P (*t
))
472 /* Remove everything we don't generate debug info for. */
473 else if (DECL_IGNORED_P (*t
))
475 *t
= DECL_CHAIN (*t
);
479 /* When we are outputting debug info, we usually want to output
480 info about optimized-out variables in the scope blocks.
481 Exception are the scope blocks not containing any instructions
482 at all so user can't get into the scopes at first place. */
483 else if (is_used_p (*t
))
485 else if (TREE_CODE (*t
) == LABEL_DECL
&& TREE_USED (*t
))
486 /* For labels that are still used in the IL, the decision to
487 preserve them must not depend DEBUG_INFO_LEVEL, otherwise we
488 risk having different ordering in debug vs. non-debug builds
489 during inlining or versioning.
490 A label appearing here (we have already checked DECL_IGNORED_P)
491 should not be used in the IL unless it has been explicitly used
492 before, so we use TREE_USED as an approximation. */
493 /* In principle, we should do the same here as for the debug case
494 below, however, when debugging, there might be additional nested
495 levels that keep an upper level with a label live, so we have to
496 force this block to be considered used, too. */
499 /* When we are not doing full debug info, we however can keep around
500 only the used variables for cfgexpand's memory packing saving quite
503 For sake of -g3, we keep around those vars but we don't count this as
504 use of block, so innermost block with no used vars and no instructions
505 can be considered dead. We only want to keep around blocks user can
506 breakpoint into and ask about value of optimized out variables.
508 Similarly we need to keep around types at least until all
509 variables of all nested blocks are gone. We track no
510 information on whether given type is used or not, so we have
511 to keep them even when not emitting debug information,
512 otherwise we may end up remapping variables and their (local)
513 types in different orders depending on whether debug
514 information is being generated. */
516 else if (TREE_CODE (*t
) == TYPE_DECL
517 || debug_info_level
== DINFO_LEVEL_NORMAL
518 || debug_info_level
== DINFO_LEVEL_VERBOSE
)
522 *t
= DECL_CHAIN (*t
);
527 for (t
= &BLOCK_SUBBLOCKS (scope
); *t
;)
528 if (remove_unused_scope_block_p (*t
))
530 if (BLOCK_SUBBLOCKS (*t
))
532 tree next
= BLOCK_CHAIN (*t
);
533 tree supercontext
= BLOCK_SUPERCONTEXT (*t
);
535 *t
= BLOCK_SUBBLOCKS (*t
);
536 while (BLOCK_CHAIN (*t
))
538 BLOCK_SUPERCONTEXT (*t
) = supercontext
;
539 t
= &BLOCK_CHAIN (*t
);
541 BLOCK_CHAIN (*t
) = next
;
542 BLOCK_SUPERCONTEXT (*t
) = supercontext
;
543 t
= &BLOCK_CHAIN (*t
);
547 *t
= BLOCK_CHAIN (*t
);
551 t
= &BLOCK_CHAIN (*t
);
558 /* Outer scope is always used. */
559 else if (!BLOCK_SUPERCONTEXT (scope
)
560 || TREE_CODE (BLOCK_SUPERCONTEXT (scope
)) == FUNCTION_DECL
)
562 /* Innermost blocks with no live variables nor statements can be always
564 else if (!nsubblocks
)
566 /* For terse debug info we can eliminate info on unused variables. */
567 else if (debug_info_level
== DINFO_LEVEL_NONE
568 || debug_info_level
== DINFO_LEVEL_TERSE
)
570 /* Even for -g0/-g1 don't prune outer scopes from artificial
571 functions, otherwise diagnostics using tree_nonartificial_location
572 will not be emitted properly. */
573 if (inlined_function_outer_scope_p (scope
))
578 && TREE_CODE (ao
) == BLOCK
579 && BLOCK_ABSTRACT_ORIGIN (ao
) != ao
)
580 ao
= BLOCK_ABSTRACT_ORIGIN (ao
);
582 && TREE_CODE (ao
) == FUNCTION_DECL
583 && DECL_DECLARED_INLINE_P (ao
)
584 && lookup_attribute ("artificial", DECL_ATTRIBUTES (ao
)))
588 else if (BLOCK_VARS (scope
) || BLOCK_NUM_NONLOCALIZED_VARS (scope
))
590 /* See if this block is important for representation of inlined function.
591 Inlined functions are always represented by block with
592 block_ultimate_origin being set to FUNCTION_DECL and DECL_SOURCE_LOCATION
594 else if (inlined_function_outer_scope_p (scope
))
597 /* Verfify that only blocks with source location set
598 are entry points to the inlined functions. */
599 gcc_assert (LOCATION_LOCUS (BLOCK_SOURCE_LOCATION (scope
))
600 == UNKNOWN_LOCATION
);
602 TREE_USED (scope
) = !unused
;
606 /* Mark all VAR_DECLS under *EXPR_P as used, so that they won't be
607 eliminated during the tree->rtl conversion process. */
610 mark_all_vars_used (tree
*expr_p
)
612 walk_tree (expr_p
, mark_all_vars_used_1
, NULL
, NULL
);
615 /* Helper function for clear_unused_block_pointer, called via walk_tree. */
618 clear_unused_block_pointer_1 (tree
*tp
, int *, void *)
620 if (EXPR_P (*tp
) && TREE_BLOCK (*tp
)
621 && !TREE_USED (TREE_BLOCK (*tp
)))
622 TREE_SET_BLOCK (*tp
, NULL
);
626 /* Set all block pointer in debug or clobber stmt to NULL if the block
627 is unused, so that they will not be streamed out. */
630 clear_unused_block_pointer (void)
633 gimple_stmt_iterator gsi
;
636 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
640 gimple stmt
= gsi_stmt (gsi
);
642 if (!is_gimple_debug (stmt
) && !gimple_clobber_p (stmt
))
644 b
= gimple_block (stmt
);
645 if (b
&& !TREE_USED (b
))
646 gimple_set_block (stmt
, NULL
);
647 for (i
= 0; i
< gimple_num_ops (stmt
); i
++)
648 walk_tree (gimple_op_ptr (stmt
, i
), clear_unused_block_pointer_1
,
653 /* Dump scope blocks starting at SCOPE to FILE. INDENT is the
654 indentation level and FLAGS is as in print_generic_expr. */
657 dump_scope_block (FILE *file
, int indent
, tree scope
, int flags
)
662 fprintf (file
, "\n%*s{ Scope block #%i%s%s",indent
, "" , BLOCK_NUMBER (scope
),
663 TREE_USED (scope
) ? "" : " (unused)",
664 BLOCK_ABSTRACT (scope
) ? " (abstract)": "");
665 if (LOCATION_LOCUS (BLOCK_SOURCE_LOCATION (scope
)) != UNKNOWN_LOCATION
)
667 expanded_location s
= expand_location (BLOCK_SOURCE_LOCATION (scope
));
668 fprintf (file
, " %s:%i", s
.file
, s
.line
);
670 if (BLOCK_ABSTRACT_ORIGIN (scope
))
672 tree origin
= block_ultimate_origin (scope
);
675 fprintf (file
, " Originating from :");
677 print_generic_decl (file
, origin
, flags
);
679 fprintf (file
, "#%i", BLOCK_NUMBER (origin
));
682 fprintf (file
, " \n");
683 for (var
= BLOCK_VARS (scope
); var
; var
= DECL_CHAIN (var
))
685 fprintf (file
, "%*s", indent
, "");
686 print_generic_decl (file
, var
, flags
);
687 fprintf (file
, "\n");
689 for (i
= 0; i
< BLOCK_NUM_NONLOCALIZED_VARS (scope
); i
++)
691 fprintf (file
, "%*s",indent
, "");
692 print_generic_decl (file
, BLOCK_NONLOCALIZED_VAR (scope
, i
),
694 fprintf (file
, " (nonlocalized)\n");
696 for (t
= BLOCK_SUBBLOCKS (scope
); t
; t
= BLOCK_CHAIN (t
))
697 dump_scope_block (file
, indent
+ 2, t
, flags
);
698 fprintf (file
, "\n%*s}\n",indent
, "");
701 /* Dump the tree of lexical scopes starting at SCOPE to stderr. FLAGS
702 is as in print_generic_expr. */
705 debug_scope_block (tree scope
, int flags
)
707 dump_scope_block (stderr
, 0, scope
, flags
);
711 /* Dump the tree of lexical scopes of current_function_decl to FILE.
712 FLAGS is as in print_generic_expr. */
715 dump_scope_blocks (FILE *file
, int flags
)
717 dump_scope_block (file
, 0, DECL_INITIAL (current_function_decl
), flags
);
721 /* Dump the tree of lexical scopes of current_function_decl to stderr.
722 FLAGS is as in print_generic_expr. */
725 debug_scope_blocks (int flags
)
727 dump_scope_blocks (stderr
, flags
);
730 /* Remove local variables that are not referenced in the IL. */
733 remove_unused_locals (void)
737 unsigned srcidx
, dstidx
, num
;
738 bool have_local_clobbers
= false;
740 /* Removing declarations from lexical blocks when not optimizing is
741 not only a waste of time, it actually causes differences in stack
746 timevar_push (TV_REMOVE_UNUSED
);
748 mark_scope_block_unused (DECL_INITIAL (current_function_decl
));
750 usedvars
= BITMAP_ALLOC (NULL
);
752 /* Walk the CFG marking all referenced symbols. */
755 gimple_stmt_iterator gsi
;
760 /* Walk the statements. */
761 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
763 gimple stmt
= gsi_stmt (gsi
);
764 tree b
= gimple_block (stmt
);
766 if (is_gimple_debug (stmt
))
769 if (gimple_clobber_p (stmt
))
771 have_local_clobbers
= true;
776 TREE_USED (b
) = true;
778 for (i
= 0; i
< gimple_num_ops (stmt
); i
++)
779 mark_all_vars_used (gimple_op_ptr (gsi_stmt (gsi
), i
));
782 for (gsi
= gsi_start_phis (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
787 gimple phi
= gsi_stmt (gsi
);
789 if (virtual_operand_p (gimple_phi_result (phi
)))
792 def
= gimple_phi_result (phi
);
793 mark_all_vars_used (&def
);
795 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_ALL_USES
)
797 tree arg
= USE_FROM_PTR (arg_p
);
798 int index
= PHI_ARG_INDEX_FROM_USE (arg_p
);
800 LOCATION_BLOCK (gimple_phi_arg_location (phi
, index
));
802 TREE_USED (block
) = true;
803 mark_all_vars_used (&arg
);
807 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
808 if (LOCATION_BLOCK (e
->goto_locus
) != NULL
)
809 TREE_USED (LOCATION_BLOCK (e
->goto_locus
)) = true;
812 /* We do a two-pass approach about the out-of-scope clobbers. We want
813 to remove them if they are the only references to a local variable,
814 but we want to retain them when there's any other. So the first pass
815 ignores them, and the second pass (if there were any) tries to remove
817 if (have_local_clobbers
)
820 gimple_stmt_iterator gsi
;
822 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
);)
824 gimple stmt
= gsi_stmt (gsi
);
825 tree b
= gimple_block (stmt
);
827 if (gimple_clobber_p (stmt
))
829 tree lhs
= gimple_assign_lhs (stmt
);
830 tree base
= get_base_address (lhs
);
831 /* Remove clobbers referencing unused vars, or clobbers
832 with MEM_REF lhs referencing uninitialized pointers. */
833 if ((TREE_CODE (base
) == VAR_DECL
&& !is_used_p (base
))
834 || (TREE_CODE (lhs
) == MEM_REF
835 && TREE_CODE (TREE_OPERAND (lhs
, 0)) == SSA_NAME
836 && SSA_NAME_IS_DEFAULT_DEF (TREE_OPERAND (lhs
, 0))
837 && (TREE_CODE (SSA_NAME_VAR (TREE_OPERAND (lhs
, 0)))
840 unlink_stmt_vdef (stmt
);
841 gsi_remove (&gsi
, true);
846 TREE_USED (b
) = true;
852 cfun
->has_local_explicit_reg_vars
= false;
854 /* Remove unmarked local and global vars from local_decls. */
855 num
= vec_safe_length (cfun
->local_decls
);
856 for (srcidx
= 0, dstidx
= 0; srcidx
< num
; srcidx
++)
858 var
= (*cfun
->local_decls
)[srcidx
];
859 if (TREE_CODE (var
) == VAR_DECL
)
861 if (!is_used_p (var
))
864 if (cfun
->nonlocal_goto_save_area
865 && TREE_OPERAND (cfun
->nonlocal_goto_save_area
, 0) == var
)
866 cfun
->nonlocal_goto_save_area
= NULL
;
867 /* Release any default def associated with var. */
868 if ((def
= ssa_default_def (cfun
, var
)) != NULL_TREE
)
870 set_ssa_default_def (cfun
, var
, NULL_TREE
);
871 release_ssa_name (def
);
876 if (TREE_CODE (var
) == VAR_DECL
877 && DECL_HARD_REGISTER (var
)
878 && !is_global_var (var
))
879 cfun
->has_local_explicit_reg_vars
= true;
881 if (srcidx
!= dstidx
)
882 (*cfun
->local_decls
)[dstidx
] = var
;
887 statistics_counter_event (cfun
, "unused VAR_DECLs removed", num
- dstidx
);
888 cfun
->local_decls
->truncate (dstidx
);
891 remove_unused_scope_block_p (DECL_INITIAL (current_function_decl
));
892 clear_unused_block_pointer ();
894 BITMAP_FREE (usedvars
);
896 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
898 fprintf (dump_file
, "Scope blocks after cleanups:\n");
899 dump_scope_blocks (dump_file
, dump_flags
);
902 timevar_pop (TV_REMOVE_UNUSED
);
905 /* Obstack for globale liveness info bitmaps. We don't want to put these
906 on the default obstack because these bitmaps can grow quite large and
907 we'll hold on to all that memory until the end of the compiler run.
908 As a bonus, delete_tree_live_info can destroy all the bitmaps by just
909 releasing the whole obstack. */
910 static bitmap_obstack liveness_bitmap_obstack
;
912 /* Allocate and return a new live range information object base on MAP. */
914 static tree_live_info_p
915 new_tree_live_info (var_map map
)
917 tree_live_info_p live
;
920 live
= XNEW (struct tree_live_info_d
);
922 live
->num_blocks
= last_basic_block
;
924 live
->livein
= XNEWVEC (bitmap_head
, last_basic_block
);
926 bitmap_initialize (&live
->livein
[bb
->index
], &liveness_bitmap_obstack
);
928 live
->liveout
= XNEWVEC (bitmap_head
, last_basic_block
);
930 bitmap_initialize (&live
->liveout
[bb
->index
], &liveness_bitmap_obstack
);
932 live
->work_stack
= XNEWVEC (int, last_basic_block
);
933 live
->stack_top
= live
->work_stack
;
935 live
->global
= BITMAP_ALLOC (&liveness_bitmap_obstack
);
940 /* Free storage for live range info object LIVE. */
943 delete_tree_live_info (tree_live_info_p live
)
945 bitmap_obstack_release (&liveness_bitmap_obstack
);
946 free (live
->work_stack
);
947 free (live
->liveout
);
953 /* Visit basic block BB and propagate any required live on entry bits from
954 LIVE into the predecessors. VISITED is the bitmap of visited blocks.
955 TMP is a temporary work bitmap which is passed in to avoid reallocating
959 loe_visit_block (tree_live_info_p live
, basic_block bb
, sbitmap visited
,
967 gcc_assert (!bitmap_bit_p (visited
, bb
->index
));
969 bitmap_set_bit (visited
, bb
->index
);
970 loe
= live_on_entry (live
, bb
);
972 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
975 if (pred_bb
== ENTRY_BLOCK_PTR
)
977 /* TMP is variables live-on-entry from BB that aren't defined in the
978 predecessor block. This should be the live on entry vars to pred.
979 Note that liveout is the DEFs in a block while live on entry is
981 bitmap_and_compl (tmp
, loe
, &live
->liveout
[pred_bb
->index
]);
983 /* Add these bits to live-on-entry for the pred. if there are any
984 changes, and pred_bb has been visited already, add it to the
986 change
= bitmap_ior_into (live_on_entry (live
, pred_bb
), tmp
);
987 if (bitmap_bit_p (visited
, pred_bb
->index
) && change
)
989 bitmap_clear_bit (visited
, pred_bb
->index
);
990 *(live
->stack_top
)++ = pred_bb
->index
;
996 /* Using LIVE, fill in all the live-on-entry blocks between the defs and uses
997 of all the variables. */
1000 live_worklist (tree_live_info_p live
)
1004 sbitmap visited
= sbitmap_alloc (last_basic_block
+ 1);
1005 bitmap tmp
= BITMAP_ALLOC (&liveness_bitmap_obstack
);
1007 bitmap_clear (visited
);
1009 /* Visit all the blocks in reverse order and propagate live on entry values
1010 into the predecessors blocks. */
1011 FOR_EACH_BB_REVERSE (bb
)
1012 loe_visit_block (live
, bb
, visited
, tmp
);
1014 /* Process any blocks which require further iteration. */
1015 while (live
->stack_top
!= live
->work_stack
)
1017 b
= *--(live
->stack_top
);
1018 loe_visit_block (live
, BASIC_BLOCK (b
), visited
, tmp
);
1022 sbitmap_free (visited
);
1026 /* Calculate the initial live on entry vector for SSA_NAME using immediate_use
1027 links. Set the live on entry fields in LIVE. Def's are marked temporarily
1028 in the liveout vector. */
1031 set_var_live_on_entry (tree ssa_name
, tree_live_info_p live
)
1036 basic_block def_bb
= NULL
;
1037 imm_use_iterator imm_iter
;
1038 bool global
= false;
1040 p
= var_to_partition (live
->map
, ssa_name
);
1041 if (p
== NO_PARTITION
)
1044 stmt
= SSA_NAME_DEF_STMT (ssa_name
);
1047 def_bb
= gimple_bb (stmt
);
1048 /* Mark defs in liveout bitmap temporarily. */
1050 bitmap_set_bit (&live
->liveout
[def_bb
->index
], p
);
1053 def_bb
= ENTRY_BLOCK_PTR
;
1055 /* Visit each use of SSA_NAME and if it isn't in the same block as the def,
1056 add it to the list of live on entry blocks. */
1057 FOR_EACH_IMM_USE_FAST (use
, imm_iter
, ssa_name
)
1059 gimple use_stmt
= USE_STMT (use
);
1060 basic_block add_block
= NULL
;
1062 if (gimple_code (use_stmt
) == GIMPLE_PHI
)
1064 /* Uses in PHI's are considered to be live at exit of the SRC block
1065 as this is where a copy would be inserted. Check to see if it is
1066 defined in that block, or whether its live on entry. */
1067 int index
= PHI_ARG_INDEX_FROM_USE (use
);
1068 edge e
= gimple_phi_arg_edge (use_stmt
, index
);
1069 if (e
->src
!= ENTRY_BLOCK_PTR
)
1071 if (e
->src
!= def_bb
)
1075 else if (is_gimple_debug (use_stmt
))
1079 /* If its not defined in this block, its live on entry. */
1080 basic_block use_bb
= gimple_bb (use_stmt
);
1081 if (use_bb
!= def_bb
)
1085 /* If there was a live on entry use, set the bit. */
1089 bitmap_set_bit (&live
->livein
[add_block
->index
], p
);
1093 /* If SSA_NAME is live on entry to at least one block, fill in all the live
1094 on entry blocks between the def and all the uses. */
1096 bitmap_set_bit (live
->global
, p
);
1100 /* Calculate the live on exit vectors based on the entry info in LIVEINFO. */
1103 calculate_live_on_exit (tree_live_info_p liveinfo
)
1109 /* live on entry calculations used liveout vectors for defs, clear them. */
1111 bitmap_clear (&liveinfo
->liveout
[bb
->index
]);
1113 /* Set all the live-on-exit bits for uses in PHIs. */
1116 gimple_stmt_iterator gsi
;
1119 /* Mark the PHI arguments which are live on exit to the pred block. */
1120 for (gsi
= gsi_start_phis (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1122 gimple phi
= gsi_stmt (gsi
);
1123 for (i
= 0; i
< gimple_phi_num_args (phi
); i
++)
1125 tree t
= PHI_ARG_DEF (phi
, i
);
1128 if (TREE_CODE (t
) != SSA_NAME
)
1131 p
= var_to_partition (liveinfo
->map
, t
);
1132 if (p
== NO_PARTITION
)
1134 e
= gimple_phi_arg_edge (phi
, i
);
1135 if (e
->src
!= ENTRY_BLOCK_PTR
)
1136 bitmap_set_bit (&liveinfo
->liveout
[e
->src
->index
], p
);
1140 /* Add each successors live on entry to this bock live on exit. */
1141 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1142 if (e
->dest
!= EXIT_BLOCK_PTR
)
1143 bitmap_ior_into (&liveinfo
->liveout
[bb
->index
],
1144 live_on_entry (liveinfo
, e
->dest
));
1149 /* Given partition map MAP, calculate all the live on entry bitmaps for
1150 each partition. Return a new live info object. */
1153 calculate_live_ranges (var_map map
)
1157 tree_live_info_p live
;
1159 bitmap_obstack_initialize (&liveness_bitmap_obstack
);
1160 live
= new_tree_live_info (map
);
1161 for (i
= 0; i
< num_var_partitions (map
); i
++)
1163 var
= partition_to_var (map
, i
);
1164 if (var
!= NULL_TREE
)
1165 set_var_live_on_entry (var
, live
);
1168 live_worklist (live
);
1170 #ifdef ENABLE_CHECKING
1171 verify_live_on_entry (live
);
1174 calculate_live_on_exit (live
);
1179 /* Output partition map MAP to file F. */
1182 dump_var_map (FILE *f
, var_map map
)
1188 fprintf (f
, "\nPartition map \n\n");
1190 for (x
= 0; x
< map
->num_partitions
; x
++)
1192 if (map
->view_to_partition
!= NULL
)
1193 p
= map
->view_to_partition
[x
];
1197 if (ssa_name (p
) == NULL_TREE
1198 || virtual_operand_p (ssa_name (p
)))
1202 for (y
= 1; y
< num_ssa_names
; y
++)
1204 p
= partition_find (map
->var_partition
, y
);
1205 if (map
->partition_to_view
)
1206 p
= map
->partition_to_view
[p
];
1211 fprintf(f
, "Partition %d (", x
);
1212 print_generic_expr (f
, partition_to_var (map
, p
), TDF_SLIM
);
1215 fprintf (f
, "%d ", y
);
1225 /* Generic dump for the above. */
1228 debug (_var_map
&ref
)
1230 dump_var_map (stderr
, &ref
);
1234 debug (_var_map
*ptr
)
1239 fprintf (stderr
, "<nil>\n");
1243 /* Output live range info LIVE to file F, controlled by FLAG. */
1246 dump_live_info (FILE *f
, tree_live_info_p live
, int flag
)
1250 var_map map
= live
->map
;
1253 if ((flag
& LIVEDUMP_ENTRY
) && live
->livein
)
1257 fprintf (f
, "\nLive on entry to BB%d : ", bb
->index
);
1258 EXECUTE_IF_SET_IN_BITMAP (&live
->livein
[bb
->index
], 0, i
, bi
)
1260 print_generic_expr (f
, partition_to_var (map
, i
), TDF_SLIM
);
1267 if ((flag
& LIVEDUMP_EXIT
) && live
->liveout
)
1271 fprintf (f
, "\nLive on exit from BB%d : ", bb
->index
);
1272 EXECUTE_IF_SET_IN_BITMAP (&live
->liveout
[bb
->index
], 0, i
, bi
)
1274 print_generic_expr (f
, partition_to_var (map
, i
), TDF_SLIM
);
1283 /* Generic dump for the above. */
1286 debug (tree_live_info_d
&ref
)
1288 dump_live_info (stderr
, &ref
, 0);
1292 debug (tree_live_info_d
*ptr
)
1297 fprintf (stderr
, "<nil>\n");
1301 #ifdef ENABLE_CHECKING
1302 /* Verify that SSA_VAR is a non-virtual SSA_NAME. */
1305 register_ssa_partition_check (tree ssa_var
)
1307 gcc_assert (TREE_CODE (ssa_var
) == SSA_NAME
);
1308 if (virtual_operand_p (ssa_var
))
1310 fprintf (stderr
, "Illegally registering a virtual SSA name :");
1311 print_generic_expr (stderr
, ssa_var
, TDF_SLIM
);
1312 fprintf (stderr
, " in the SSA->Normal phase.\n");
1313 internal_error ("SSA corruption");
1318 /* Verify that the info in LIVE matches the current cfg. */
1321 verify_live_on_entry (tree_live_info_p live
)
1330 var_map map
= live
->map
;
1332 /* Check for live on entry partitions and report those with a DEF in
1333 the program. This will typically mean an optimization has done
1335 bb
= ENTRY_BLOCK_PTR
;
1337 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1339 int entry_block
= e
->dest
->index
;
1340 if (e
->dest
== EXIT_BLOCK_PTR
)
1342 for (i
= 0; i
< (unsigned)num_var_partitions (map
); i
++)
1347 var
= partition_to_var (map
, i
);
1348 stmt
= SSA_NAME_DEF_STMT (var
);
1349 tmp
= gimple_bb (stmt
);
1350 if (SSA_NAME_VAR (var
))
1351 d
= ssa_default_def (cfun
, SSA_NAME_VAR (var
));
1353 loe
= live_on_entry (live
, e
->dest
);
1354 if (loe
&& bitmap_bit_p (loe
, i
))
1356 if (!gimple_nop_p (stmt
))
1359 print_generic_expr (stderr
, var
, TDF_SLIM
);
1360 fprintf (stderr
, " is defined ");
1362 fprintf (stderr
, " in BB%d, ", tmp
->index
);
1363 fprintf (stderr
, "by:\n");
1364 print_gimple_stmt (stderr
, stmt
, 0, TDF_SLIM
);
1365 fprintf (stderr
, "\nIt is also live-on-entry to entry BB %d",
1367 fprintf (stderr
, " So it appears to have multiple defs.\n");
1374 print_generic_expr (stderr
, var
, TDF_SLIM
);
1375 fprintf (stderr
, " is live-on-entry to BB%d ",
1379 fprintf (stderr
, " but is not the default def of ");
1380 print_generic_expr (stderr
, d
, TDF_SLIM
);
1381 fprintf (stderr
, "\n");
1384 fprintf (stderr
, " and there is no default def.\n");
1391 /* The only way this var shouldn't be marked live on entry is
1392 if it occurs in a PHI argument of the block. */
1395 gimple_stmt_iterator gsi
;
1396 for (gsi
= gsi_start_phis (e
->dest
);
1397 !gsi_end_p (gsi
) && !ok
;
1400 gimple phi
= gsi_stmt (gsi
);
1401 for (z
= 0; z
< gimple_phi_num_args (phi
); z
++)
1402 if (var
== gimple_phi_arg_def (phi
, z
))
1411 print_generic_expr (stderr
, var
, TDF_SLIM
);
1412 fprintf (stderr
, " is not marked live-on-entry to entry BB%d ",
1414 fprintf (stderr
, "but it is a default def so it should be.\n");
1418 gcc_assert (num
<= 0);