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 "gimple-pretty-print.h"
29 #include "tree-flow.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
)
65 struct tree_int_map
*m
, *mapstorage
;
67 num_part
= num_var_partitions (map
);
68 tree_to_index
= htab_create (num_part
, tree_map_base_hash
,
69 tree_int_map_eq
, NULL
);
70 /* We can have at most num_part entries in the hash tables, so it's
71 enough to allocate so many map elements once, saving some malloc
73 mapstorage
= m
= XNEWVEC (struct tree_int_map
, num_part
);
75 /* If a base table already exists, clear it, otherwise create it. */
76 free (map
->partition_to_base_index
);
77 map
->partition_to_base_index
= (int *) xmalloc (sizeof (int) * num_part
);
79 /* Build the base variable list, and point partitions at their bases. */
80 for (x
= 0; x
< num_part
; x
++)
82 struct tree_int_map
**slot
;
84 var
= partition_to_var (map
, x
);
85 if (SSA_NAME_VAR (var
))
86 m
->base
.from
= SSA_NAME_VAR (var
);
88 /* This restricts what anonymous SSA names we can coalesce
89 as it restricts the sets we compute conflicts for.
90 Using TREE_TYPE to generate sets is the easies as
91 type equivalency also holds for SSA names with the same
93 m
->base
.from
= TREE_TYPE (var
);
94 /* If base variable hasn't been seen, set it up. */
95 slot
= (struct tree_int_map
**) htab_find_slot (tree_to_index
,
99 baseindex
= m
- mapstorage
;
105 baseindex
= (*slot
)->to
;
106 map
->partition_to_base_index
[x
] = baseindex
;
109 map
->num_basevars
= m
- mapstorage
;
112 htab_delete (tree_to_index
);
116 /* Remove the base table in MAP. */
119 var_map_base_fini (var_map map
)
121 /* Free the basevar info if it is present. */
122 if (map
->partition_to_base_index
!= NULL
)
124 free (map
->partition_to_base_index
);
125 map
->partition_to_base_index
= NULL
;
126 map
->num_basevars
= 0;
129 /* Create a variable partition map of SIZE, initialize and return it. */
132 init_var_map (int size
)
136 map
= (var_map
) xmalloc (sizeof (struct _var_map
));
137 map
->var_partition
= partition_new (size
);
139 map
->partition_to_view
= NULL
;
140 map
->view_to_partition
= NULL
;
141 map
->num_partitions
= size
;
142 map
->partition_size
= size
;
143 map
->num_basevars
= 0;
144 map
->partition_to_base_index
= NULL
;
149 /* Free memory associated with MAP. */
152 delete_var_map (var_map map
)
154 var_map_base_fini (map
);
155 partition_delete (map
->var_partition
);
156 free (map
->partition_to_view
);
157 free (map
->view_to_partition
);
162 /* This function will combine the partitions in MAP for VAR1 and VAR2. It
163 Returns the partition which represents the new partition. If the two
164 partitions cannot be combined, NO_PARTITION is returned. */
167 var_union (var_map map
, tree var1
, tree var2
)
171 gcc_assert (TREE_CODE (var1
) == SSA_NAME
);
172 gcc_assert (TREE_CODE (var2
) == SSA_NAME
);
174 /* This is independent of partition_to_view. If partition_to_view is
175 on, then whichever one of these partitions is absorbed will never have a
176 dereference into the partition_to_view array any more. */
178 p1
= partition_find (map
->var_partition
, SSA_NAME_VERSION (var1
));
179 p2
= partition_find (map
->var_partition
, SSA_NAME_VERSION (var2
));
181 gcc_assert (p1
!= NO_PARTITION
);
182 gcc_assert (p2
!= NO_PARTITION
);
187 p3
= partition_union (map
->var_partition
, p1
, p2
);
189 if (map
->partition_to_view
)
190 p3
= map
->partition_to_view
[p3
];
196 /* Compress the partition numbers in MAP such that they fall in the range
197 0..(num_partitions-1) instead of wherever they turned out during
198 the partitioning exercise. This removes any references to unused
199 partitions, thereby allowing bitmaps and other vectors to be much
202 This is implemented such that compaction doesn't affect partitioning.
203 Ie., once partitions are created and possibly merged, running one
204 or more different kind of compaction will not affect the partitions
205 themselves. Their index might change, but all the same variables will
206 still be members of the same partition group. This allows work on reduced
207 sets, and no loss of information when a larger set is later desired.
209 In particular, coalescing can work on partitions which have 2 or more
210 definitions, and then 'recompact' later to include all the single
211 definitions for assignment to program variables. */
214 /* Set MAP back to the initial state of having no partition view. Return a
215 bitmap which has a bit set for each partition number which is in use in the
219 partition_view_init (var_map map
)
225 used
= BITMAP_ALLOC (NULL
);
227 /* Already in a view? Abandon the old one. */
228 if (map
->partition_to_view
)
230 free (map
->partition_to_view
);
231 map
->partition_to_view
= NULL
;
233 if (map
->view_to_partition
)
235 free (map
->view_to_partition
);
236 map
->view_to_partition
= NULL
;
239 /* Find out which partitions are actually referenced. */
240 for (x
= 0; x
< map
->partition_size
; x
++)
242 tmp
= partition_find (map
->var_partition
, x
);
243 if (ssa_name (tmp
) != NULL_TREE
&& !virtual_operand_p (ssa_name (tmp
))
244 && (!has_zero_uses (ssa_name (tmp
))
245 || !SSA_NAME_IS_DEFAULT_DEF (ssa_name (tmp
))))
246 bitmap_set_bit (used
, tmp
);
249 map
->num_partitions
= map
->partition_size
;
254 /* This routine will finalize the view data for MAP based on the partitions
255 set in SELECTED. This is either the same bitmap returned from
256 partition_view_init, or a trimmed down version if some of those partitions
257 were not desired in this view. SELECTED is freed before returning. */
260 partition_view_fini (var_map map
, bitmap selected
)
263 unsigned count
, i
, x
, limit
;
265 gcc_assert (selected
);
267 count
= bitmap_count_bits (selected
);
268 limit
= map
->partition_size
;
270 /* If its a one-to-one ratio, we don't need any view compaction. */
273 map
->partition_to_view
= (int *)xmalloc (limit
* sizeof (int));
274 memset (map
->partition_to_view
, 0xff, (limit
* sizeof (int)));
275 map
->view_to_partition
= (int *)xmalloc (count
* sizeof (int));
278 /* Give each selected partition an index. */
279 EXECUTE_IF_SET_IN_BITMAP (selected
, 0, x
, bi
)
281 map
->partition_to_view
[x
] = i
;
282 map
->view_to_partition
[i
] = x
;
285 gcc_assert (i
== count
);
286 map
->num_partitions
= i
;
289 BITMAP_FREE (selected
);
293 /* Create a partition view which includes all the used partitions in MAP. If
294 WANT_BASES is true, create the base variable map as well. */
297 partition_view_normal (var_map map
, bool want_bases
)
301 used
= partition_view_init (map
);
302 partition_view_fini (map
, used
);
305 var_map_base_init (map
);
307 var_map_base_fini (map
);
311 /* Create a partition view in MAP which includes just partitions which occur in
312 the bitmap ONLY. If WANT_BASES is true, create the base variable map
316 partition_view_bitmap (var_map map
, bitmap only
, bool want_bases
)
319 bitmap new_partitions
= BITMAP_ALLOC (NULL
);
323 used
= partition_view_init (map
);
324 EXECUTE_IF_SET_IN_BITMAP (only
, 0, x
, bi
)
326 p
= partition_find (map
->var_partition
, x
);
327 gcc_assert (bitmap_bit_p (used
, p
));
328 bitmap_set_bit (new_partitions
, p
);
330 partition_view_fini (map
, new_partitions
);
333 var_map_base_init (map
);
335 var_map_base_fini (map
);
339 static bitmap usedvars
;
341 /* Mark VAR as used, so that it'll be preserved during rtl expansion.
342 Returns true if VAR wasn't marked before. */
345 set_is_used (tree var
)
347 return bitmap_set_bit (usedvars
, DECL_UID (var
));
350 /* Return true if VAR is marked as used. */
355 return bitmap_bit_p (usedvars
, DECL_UID (var
));
358 static inline void mark_all_vars_used (tree
*);
360 /* Helper function for mark_all_vars_used, called via walk_tree. */
363 mark_all_vars_used_1 (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
366 enum tree_code_class c
= TREE_CODE_CLASS (TREE_CODE (t
));
369 if (TREE_CODE (t
) == SSA_NAME
)
372 t
= SSA_NAME_VAR (t
);
377 if (IS_EXPR_CODE_CLASS (c
)
378 && (b
= TREE_BLOCK (t
)) != NULL
)
379 TREE_USED (b
) = true;
381 /* Ignore TMR_OFFSET and TMR_STEP for TARGET_MEM_REFS, as those
382 fields do not contain vars. */
383 if (TREE_CODE (t
) == TARGET_MEM_REF
)
385 mark_all_vars_used (&TMR_BASE (t
));
386 mark_all_vars_used (&TMR_INDEX (t
));
387 mark_all_vars_used (&TMR_INDEX2 (t
));
392 /* Only need to mark VAR_DECLS; parameters and return results are not
393 eliminated as unused. */
394 if (TREE_CODE (t
) == VAR_DECL
)
396 /* When a global var becomes used for the first time also walk its
397 initializer (non global ones don't have any). */
398 if (set_is_used (t
) && is_global_var (t
))
399 mark_all_vars_used (&DECL_INITIAL (t
));
401 /* remove_unused_scope_block_p requires information about labels
402 which are not DECL_IGNORED_P to tell if they might be used in the IL. */
403 else if (TREE_CODE (t
) == LABEL_DECL
)
404 /* Although the TREE_USED values that the frontend uses would be
405 acceptable (albeit slightly over-conservative) for our purposes,
406 init_vars_expansion clears TREE_USED for LABEL_DECLs too, so we
407 must re-compute it here. */
410 if (IS_TYPE_OR_DECL_P (t
))
416 /* Mark the scope block SCOPE and its subblocks unused when they can be
417 possibly eliminated if dead. */
420 mark_scope_block_unused (tree scope
)
423 TREE_USED (scope
) = false;
424 if (!(*debug_hooks
->ignore_block
) (scope
))
425 TREE_USED (scope
) = true;
426 for (t
= BLOCK_SUBBLOCKS (scope
); t
; t
= BLOCK_CHAIN (t
))
427 mark_scope_block_unused (t
);
430 /* Look if the block is dead (by possibly eliminating its dead subblocks)
431 and return true if so.
432 Block is declared dead if:
433 1) No statements are associated with it.
434 2) Declares no live variables
435 3) All subblocks are dead
436 or there is precisely one subblocks and the block
437 has same abstract origin as outer block and declares
438 no variables, so it is pure wrapper.
439 When we are not outputting full debug info, we also eliminate dead variables
440 out of scope blocks to let them to be recycled by GGC and to save copying work
441 done by the inliner. */
444 remove_unused_scope_block_p (tree scope
)
447 bool unused
= !TREE_USED (scope
);
450 for (t
= &BLOCK_VARS (scope
); *t
; t
= next
)
452 next
= &DECL_CHAIN (*t
);
454 /* Debug info of nested function refers to the block of the
455 function. We might stil call it even if all statements
456 of function it was nested into was elliminated.
458 TODO: We can actually look into cgraph to see if function
459 will be output to file. */
460 if (TREE_CODE (*t
) == FUNCTION_DECL
)
463 /* If a decl has a value expr, we need to instantiate it
464 regardless of debug info generation, to avoid codegen
465 differences in memory overlap tests. update_equiv_regs() may
466 indirectly call validate_equiv_mem() to test whether a
467 SET_DEST overlaps with others, and if the value expr changes
468 by virtual register instantiation, we may get end up with
469 different results. */
470 else if (TREE_CODE (*t
) == VAR_DECL
&& DECL_HAS_VALUE_EXPR_P (*t
))
473 /* Remove everything we don't generate debug info for. */
474 else if (DECL_IGNORED_P (*t
))
476 *t
= DECL_CHAIN (*t
);
480 /* When we are outputting debug info, we usually want to output
481 info about optimized-out variables in the scope blocks.
482 Exception are the scope blocks not containing any instructions
483 at all so user can't get into the scopes at first place. */
484 else if (is_used_p (*t
))
486 else if (TREE_CODE (*t
) == LABEL_DECL
&& TREE_USED (*t
))
487 /* For labels that are still used in the IL, the decision to
488 preserve them must not depend DEBUG_INFO_LEVEL, otherwise we
489 risk having different ordering in debug vs. non-debug builds
490 during inlining or versioning.
491 A label appearing here (we have already checked DECL_IGNORED_P)
492 should not be used in the IL unless it has been explicitly used
493 before, so we use TREE_USED as an approximation. */
494 /* In principle, we should do the same here as for the debug case
495 below, however, when debugging, there might be additional nested
496 levels that keep an upper level with a label live, so we have to
497 force this block to be considered used, too. */
500 /* When we are not doing full debug info, we however can keep around
501 only the used variables for cfgexpand's memory packing saving quite
504 For sake of -g3, we keep around those vars but we don't count this as
505 use of block, so innermost block with no used vars and no instructions
506 can be considered dead. We only want to keep around blocks user can
507 breakpoint into and ask about value of optimized out variables.
509 Similarly we need to keep around types at least until all
510 variables of all nested blocks are gone. We track no
511 information on whether given type is used or not, so we have
512 to keep them even when not emitting debug information,
513 otherwise we may end up remapping variables and their (local)
514 types in different orders depending on whether debug
515 information is being generated. */
517 else if (TREE_CODE (*t
) == TYPE_DECL
518 || debug_info_level
== DINFO_LEVEL_NORMAL
519 || debug_info_level
== DINFO_LEVEL_VERBOSE
)
523 *t
= DECL_CHAIN (*t
);
528 for (t
= &BLOCK_SUBBLOCKS (scope
); *t
;)
529 if (remove_unused_scope_block_p (*t
))
531 if (BLOCK_SUBBLOCKS (*t
))
533 tree next
= BLOCK_CHAIN (*t
);
534 tree supercontext
= BLOCK_SUPERCONTEXT (*t
);
536 *t
= BLOCK_SUBBLOCKS (*t
);
537 while (BLOCK_CHAIN (*t
))
539 BLOCK_SUPERCONTEXT (*t
) = supercontext
;
540 t
= &BLOCK_CHAIN (*t
);
542 BLOCK_CHAIN (*t
) = next
;
543 BLOCK_SUPERCONTEXT (*t
) = supercontext
;
544 t
= &BLOCK_CHAIN (*t
);
548 *t
= BLOCK_CHAIN (*t
);
552 t
= &BLOCK_CHAIN (*t
);
559 /* Outer scope is always used. */
560 else if (!BLOCK_SUPERCONTEXT (scope
)
561 || TREE_CODE (BLOCK_SUPERCONTEXT (scope
)) == FUNCTION_DECL
)
563 /* Innermost blocks with no live variables nor statements can be always
565 else if (!nsubblocks
)
567 /* For terse debug info we can eliminate info on unused variables. */
568 else if (debug_info_level
== DINFO_LEVEL_NONE
569 || debug_info_level
== DINFO_LEVEL_TERSE
)
571 /* Even for -g0/-g1 don't prune outer scopes from artificial
572 functions, otherwise diagnostics using tree_nonartificial_location
573 will not be emitted properly. */
574 if (inlined_function_outer_scope_p (scope
))
579 && TREE_CODE (ao
) == BLOCK
580 && BLOCK_ABSTRACT_ORIGIN (ao
) != ao
)
581 ao
= BLOCK_ABSTRACT_ORIGIN (ao
);
583 && TREE_CODE (ao
) == FUNCTION_DECL
584 && DECL_DECLARED_INLINE_P (ao
)
585 && lookup_attribute ("artificial", DECL_ATTRIBUTES (ao
)))
589 else if (BLOCK_VARS (scope
) || BLOCK_NUM_NONLOCALIZED_VARS (scope
))
591 /* See if this block is important for representation of inlined function.
592 Inlined functions are always represented by block with
593 block_ultimate_origin being set to FUNCTION_DECL and DECL_SOURCE_LOCATION
595 else if (inlined_function_outer_scope_p (scope
))
598 /* Verfify that only blocks with source location set
599 are entry points to the inlined functions. */
600 gcc_assert (BLOCK_SOURCE_LOCATION (scope
) == 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
);
616 /* Dump scope blocks starting at SCOPE to FILE. INDENT is the
617 indentation level and FLAGS is as in print_generic_expr. */
620 dump_scope_block (FILE *file
, int indent
, tree scope
, int flags
)
625 fprintf (file
, "\n%*s{ Scope block #%i%s%s",indent
, "" , BLOCK_NUMBER (scope
),
626 TREE_USED (scope
) ? "" : " (unused)",
627 BLOCK_ABSTRACT (scope
) ? " (abstract)": "");
628 if (BLOCK_SOURCE_LOCATION (scope
) != UNKNOWN_LOCATION
)
630 expanded_location s
= expand_location (BLOCK_SOURCE_LOCATION (scope
));
631 fprintf (file
, " %s:%i", s
.file
, s
.line
);
633 if (BLOCK_ABSTRACT_ORIGIN (scope
))
635 tree origin
= block_ultimate_origin (scope
);
638 fprintf (file
, " Originating from :");
640 print_generic_decl (file
, origin
, flags
);
642 fprintf (file
, "#%i", BLOCK_NUMBER (origin
));
645 fprintf (file
, " \n");
646 for (var
= BLOCK_VARS (scope
); var
; var
= DECL_CHAIN (var
))
648 fprintf (file
, "%*s", indent
, "");
649 print_generic_decl (file
, var
, flags
);
650 fprintf (file
, "\n");
652 for (i
= 0; i
< BLOCK_NUM_NONLOCALIZED_VARS (scope
); i
++)
654 fprintf (file
, "%*s",indent
, "");
655 print_generic_decl (file
, BLOCK_NONLOCALIZED_VAR (scope
, i
),
657 fprintf (file
, " (nonlocalized)\n");
659 for (t
= BLOCK_SUBBLOCKS (scope
); t
; t
= BLOCK_CHAIN (t
))
660 dump_scope_block (file
, indent
+ 2, t
, flags
);
661 fprintf (file
, "\n%*s}\n",indent
, "");
664 /* Dump the tree of lexical scopes starting at SCOPE to stderr. FLAGS
665 is as in print_generic_expr. */
668 debug_scope_block (tree scope
, int flags
)
670 dump_scope_block (stderr
, 0, scope
, flags
);
674 /* Dump the tree of lexical scopes of current_function_decl to FILE.
675 FLAGS is as in print_generic_expr. */
678 dump_scope_blocks (FILE *file
, int flags
)
680 dump_scope_block (file
, 0, DECL_INITIAL (current_function_decl
), flags
);
684 /* Dump the tree of lexical scopes of current_function_decl to stderr.
685 FLAGS is as in print_generic_expr. */
688 debug_scope_blocks (int flags
)
690 dump_scope_blocks (stderr
, flags
);
693 /* Remove local variables that are not referenced in the IL. */
696 remove_unused_locals (void)
700 unsigned srcidx
, dstidx
, num
;
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 usedvars
= BITMAP_ALLOC (NULL
);
715 /* Walk the CFG marking all referenced symbols. */
718 gimple_stmt_iterator gsi
;
723 /* Walk the statements. */
724 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
726 gimple stmt
= gsi_stmt (gsi
);
727 tree b
= gimple_block (stmt
);
729 if (is_gimple_debug (stmt
))
732 if (gimple_clobber_p (stmt
))
734 have_local_clobbers
= true;
739 TREE_USED (b
) = true;
741 for (i
= 0; i
< gimple_num_ops (stmt
); i
++)
742 mark_all_vars_used (gimple_op_ptr (gsi_stmt (gsi
), i
));
745 for (gsi
= gsi_start_phis (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
750 gimple phi
= gsi_stmt (gsi
);
752 if (virtual_operand_p (gimple_phi_result (phi
)))
755 def
= gimple_phi_result (phi
);
756 mark_all_vars_used (&def
);
758 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_ALL_USES
)
760 tree arg
= USE_FROM_PTR (arg_p
);
761 mark_all_vars_used (&arg
);
765 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
767 TREE_USED (e
->goto_block
) = true;
770 /* We do a two-pass approach about the out-of-scope clobbers. We want
771 to remove them if they are the only references to a local variable,
772 but we want to retain them when there's any other. So the first pass
773 ignores them, and the second pass (if there were any) tries to remove
775 if (have_local_clobbers
)
778 gimple_stmt_iterator gsi
;
780 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
);)
782 gimple stmt
= gsi_stmt (gsi
);
783 tree b
= gimple_block (stmt
);
785 if (gimple_clobber_p (stmt
))
787 tree lhs
= gimple_assign_lhs (stmt
);
788 if (TREE_CODE (lhs
) == VAR_DECL
&& !is_used_p (lhs
))
790 unlink_stmt_vdef (stmt
);
791 gsi_remove (&gsi
, true);
796 TREE_USED (b
) = true;
802 cfun
->has_local_explicit_reg_vars
= false;
804 /* Remove unmarked local and global vars from local_decls. */
805 num
= VEC_length (tree
, cfun
->local_decls
);
806 for (srcidx
= 0, dstidx
= 0; srcidx
< num
; srcidx
++)
808 var
= VEC_index (tree
, cfun
->local_decls
, srcidx
);
809 if (TREE_CODE (var
) == VAR_DECL
)
811 if (!is_used_p (var
))
814 if (cfun
->nonlocal_goto_save_area
815 && TREE_OPERAND (cfun
->nonlocal_goto_save_area
, 0) == var
)
816 cfun
->nonlocal_goto_save_area
= NULL
;
817 /* Release any default def associated with var. */
818 if ((def
= ssa_default_def (cfun
, var
)) != NULL_TREE
)
820 set_ssa_default_def (cfun
, var
, NULL_TREE
);
821 release_ssa_name (def
);
826 if (TREE_CODE (var
) == VAR_DECL
827 && DECL_HARD_REGISTER (var
)
828 && !is_global_var (var
))
829 cfun
->has_local_explicit_reg_vars
= true;
831 if (srcidx
!= dstidx
)
832 VEC_replace (tree
, cfun
->local_decls
, dstidx
, var
);
836 VEC_truncate (tree
, cfun
->local_decls
, dstidx
);
838 remove_unused_scope_block_p (DECL_INITIAL (current_function_decl
));
840 BITMAP_FREE (usedvars
);
842 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
844 fprintf (dump_file
, "Scope blocks after cleanups:\n");
845 dump_scope_blocks (dump_file
, dump_flags
);
848 timevar_pop (TV_REMOVE_UNUSED
);
851 /* Obstack for globale liveness info bitmaps. We don't want to put these
852 on the default obstack because these bitmaps can grow quite large and
853 we'll hold on to all that memory until the end of the compiler run.
854 As a bonus, delete_tree_live_info can destroy all the bitmaps by just
855 releasing the whole obstack. */
856 static bitmap_obstack liveness_bitmap_obstack
;
858 /* Allocate and return a new live range information object base on MAP. */
860 static tree_live_info_p
861 new_tree_live_info (var_map map
)
863 tree_live_info_p live
;
866 live
= XNEW (struct tree_live_info_d
);
868 live
->num_blocks
= last_basic_block
;
870 live
->livein
= XNEWVEC (bitmap_head
, last_basic_block
);
872 bitmap_initialize (&live
->livein
[bb
->index
], &liveness_bitmap_obstack
);
874 live
->liveout
= XNEWVEC (bitmap_head
, last_basic_block
);
876 bitmap_initialize (&live
->liveout
[bb
->index
], &liveness_bitmap_obstack
);
878 live
->work_stack
= XNEWVEC (int, last_basic_block
);
879 live
->stack_top
= live
->work_stack
;
881 live
->global
= BITMAP_ALLOC (&liveness_bitmap_obstack
);
886 /* Free storage for live range info object LIVE. */
889 delete_tree_live_info (tree_live_info_p live
)
891 bitmap_obstack_release (&liveness_bitmap_obstack
);
892 free (live
->work_stack
);
893 free (live
->liveout
);
899 /* Visit basic block BB and propagate any required live on entry bits from
900 LIVE into the predecessors. VISITED is the bitmap of visited blocks.
901 TMP is a temporary work bitmap which is passed in to avoid reallocating
905 loe_visit_block (tree_live_info_p live
, basic_block bb
, sbitmap visited
,
913 gcc_assert (!TEST_BIT (visited
, bb
->index
));
915 SET_BIT (visited
, bb
->index
);
916 loe
= live_on_entry (live
, bb
);
918 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
921 if (pred_bb
== ENTRY_BLOCK_PTR
)
923 /* TMP is variables live-on-entry from BB that aren't defined in the
924 predecessor block. This should be the live on entry vars to pred.
925 Note that liveout is the DEFs in a block while live on entry is
927 bitmap_and_compl (tmp
, loe
, &live
->liveout
[pred_bb
->index
]);
929 /* Add these bits to live-on-entry for the pred. if there are any
930 changes, and pred_bb has been visited already, add it to the
932 change
= bitmap_ior_into (live_on_entry (live
, pred_bb
), tmp
);
933 if (TEST_BIT (visited
, pred_bb
->index
) && change
)
935 RESET_BIT (visited
, pred_bb
->index
);
936 *(live
->stack_top
)++ = pred_bb
->index
;
942 /* Using LIVE, fill in all the live-on-entry blocks between the defs and uses
943 of all the variables. */
946 live_worklist (tree_live_info_p live
)
950 sbitmap visited
= sbitmap_alloc (last_basic_block
+ 1);
951 bitmap tmp
= BITMAP_ALLOC (&liveness_bitmap_obstack
);
953 sbitmap_zero (visited
);
955 /* Visit all the blocks in reverse order and propagate live on entry values
956 into the predecessors blocks. */
957 FOR_EACH_BB_REVERSE (bb
)
958 loe_visit_block (live
, bb
, visited
, tmp
);
960 /* Process any blocks which require further iteration. */
961 while (live
->stack_top
!= live
->work_stack
)
963 b
= *--(live
->stack_top
);
964 loe_visit_block (live
, BASIC_BLOCK (b
), visited
, tmp
);
968 sbitmap_free (visited
);
972 /* Calculate the initial live on entry vector for SSA_NAME using immediate_use
973 links. Set the live on entry fields in LIVE. Def's are marked temporarily
974 in the liveout vector. */
977 set_var_live_on_entry (tree ssa_name
, tree_live_info_p live
)
982 basic_block def_bb
= NULL
;
983 imm_use_iterator imm_iter
;
986 p
= var_to_partition (live
->map
, ssa_name
);
987 if (p
== NO_PARTITION
)
990 stmt
= SSA_NAME_DEF_STMT (ssa_name
);
993 def_bb
= gimple_bb (stmt
);
994 /* Mark defs in liveout bitmap temporarily. */
996 bitmap_set_bit (&live
->liveout
[def_bb
->index
], p
);
999 def_bb
= ENTRY_BLOCK_PTR
;
1001 /* Visit each use of SSA_NAME and if it isn't in the same block as the def,
1002 add it to the list of live on entry blocks. */
1003 FOR_EACH_IMM_USE_FAST (use
, imm_iter
, ssa_name
)
1005 gimple use_stmt
= USE_STMT (use
);
1006 basic_block add_block
= NULL
;
1008 if (gimple_code (use_stmt
) == GIMPLE_PHI
)
1010 /* Uses in PHI's are considered to be live at exit of the SRC block
1011 as this is where a copy would be inserted. Check to see if it is
1012 defined in that block, or whether its live on entry. */
1013 int index
= PHI_ARG_INDEX_FROM_USE (use
);
1014 edge e
= gimple_phi_arg_edge (use_stmt
, index
);
1015 if (e
->src
!= ENTRY_BLOCK_PTR
)
1017 if (e
->src
!= def_bb
)
1021 else if (is_gimple_debug (use_stmt
))
1025 /* If its not defined in this block, its live on entry. */
1026 basic_block use_bb
= gimple_bb (use_stmt
);
1027 if (use_bb
!= def_bb
)
1031 /* If there was a live on entry use, set the bit. */
1035 bitmap_set_bit (&live
->livein
[add_block
->index
], p
);
1039 /* If SSA_NAME is live on entry to at least one block, fill in all the live
1040 on entry blocks between the def and all the uses. */
1042 bitmap_set_bit (live
->global
, p
);
1046 /* Calculate the live on exit vectors based on the entry info in LIVEINFO. */
1049 calculate_live_on_exit (tree_live_info_p liveinfo
)
1055 /* live on entry calculations used liveout vectors for defs, clear them. */
1057 bitmap_clear (&liveinfo
->liveout
[bb
->index
]);
1059 /* Set all the live-on-exit bits for uses in PHIs. */
1062 gimple_stmt_iterator gsi
;
1065 /* Mark the PHI arguments which are live on exit to the pred block. */
1066 for (gsi
= gsi_start_phis (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1068 gimple phi
= gsi_stmt (gsi
);
1069 for (i
= 0; i
< gimple_phi_num_args (phi
); i
++)
1071 tree t
= PHI_ARG_DEF (phi
, i
);
1074 if (TREE_CODE (t
) != SSA_NAME
)
1077 p
= var_to_partition (liveinfo
->map
, t
);
1078 if (p
== NO_PARTITION
)
1080 e
= gimple_phi_arg_edge (phi
, i
);
1081 if (e
->src
!= ENTRY_BLOCK_PTR
)
1082 bitmap_set_bit (&liveinfo
->liveout
[e
->src
->index
], p
);
1086 /* Add each successors live on entry to this bock live on exit. */
1087 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1088 if (e
->dest
!= EXIT_BLOCK_PTR
)
1089 bitmap_ior_into (&liveinfo
->liveout
[bb
->index
],
1090 live_on_entry (liveinfo
, e
->dest
));
1095 /* Given partition map MAP, calculate all the live on entry bitmaps for
1096 each partition. Return a new live info object. */
1099 calculate_live_ranges (var_map map
)
1103 tree_live_info_p live
;
1105 bitmap_obstack_initialize (&liveness_bitmap_obstack
);
1106 live
= new_tree_live_info (map
);
1107 for (i
= 0; i
< num_var_partitions (map
); i
++)
1109 var
= partition_to_var (map
, i
);
1110 if (var
!= NULL_TREE
)
1111 set_var_live_on_entry (var
, live
);
1114 live_worklist (live
);
1116 #ifdef ENABLE_CHECKING
1117 verify_live_on_entry (live
);
1120 calculate_live_on_exit (live
);
1125 /* Output partition map MAP to file F. */
1128 dump_var_map (FILE *f
, var_map map
)
1134 fprintf (f
, "\nPartition map \n\n");
1136 for (x
= 0; x
< map
->num_partitions
; x
++)
1138 if (map
->view_to_partition
!= NULL
)
1139 p
= map
->view_to_partition
[x
];
1143 if (ssa_name (p
) == NULL_TREE
)
1147 for (y
= 1; y
< num_ssa_names
; y
++)
1149 p
= partition_find (map
->var_partition
, y
);
1150 if (map
->partition_to_view
)
1151 p
= map
->partition_to_view
[p
];
1156 fprintf(f
, "Partition %d (", x
);
1157 print_generic_expr (f
, partition_to_var (map
, p
), TDF_SLIM
);
1160 fprintf (f
, "%d ", y
);
1170 /* Output live range info LIVE to file F, controlled by FLAG. */
1173 dump_live_info (FILE *f
, tree_live_info_p live
, int flag
)
1177 var_map map
= live
->map
;
1180 if ((flag
& LIVEDUMP_ENTRY
) && live
->livein
)
1184 fprintf (f
, "\nLive on entry to BB%d : ", bb
->index
);
1185 EXECUTE_IF_SET_IN_BITMAP (&live
->livein
[bb
->index
], 0, i
, bi
)
1187 print_generic_expr (f
, partition_to_var (map
, i
), TDF_SLIM
);
1194 if ((flag
& LIVEDUMP_EXIT
) && live
->liveout
)
1198 fprintf (f
, "\nLive on exit from BB%d : ", bb
->index
);
1199 EXECUTE_IF_SET_IN_BITMAP (&live
->liveout
[bb
->index
], 0, i
, bi
)
1201 print_generic_expr (f
, partition_to_var (map
, i
), TDF_SLIM
);
1209 #ifdef ENABLE_CHECKING
1210 /* Verify that SSA_VAR is a non-virtual SSA_NAME. */
1213 register_ssa_partition_check (tree ssa_var
)
1215 gcc_assert (TREE_CODE (ssa_var
) == SSA_NAME
);
1216 if (virtual_operand_p (ssa_var
))
1218 fprintf (stderr
, "Illegally registering a virtual SSA name :");
1219 print_generic_expr (stderr
, ssa_var
, TDF_SLIM
);
1220 fprintf (stderr
, " in the SSA->Normal phase.\n");
1221 internal_error ("SSA corruption");
1226 /* Verify that the info in LIVE matches the current cfg. */
1229 verify_live_on_entry (tree_live_info_p live
)
1238 var_map map
= live
->map
;
1240 /* Check for live on entry partitions and report those with a DEF in
1241 the program. This will typically mean an optimization has done
1243 bb
= ENTRY_BLOCK_PTR
;
1245 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1247 int entry_block
= e
->dest
->index
;
1248 if (e
->dest
== EXIT_BLOCK_PTR
)
1250 for (i
= 0; i
< (unsigned)num_var_partitions (map
); i
++)
1255 var
= partition_to_var (map
, i
);
1256 stmt
= SSA_NAME_DEF_STMT (var
);
1257 tmp
= gimple_bb (stmt
);
1258 if (SSA_NAME_VAR (var
))
1259 d
= ssa_default_def (cfun
, SSA_NAME_VAR (var
));
1261 loe
= live_on_entry (live
, e
->dest
);
1262 if (loe
&& bitmap_bit_p (loe
, i
))
1264 if (!gimple_nop_p (stmt
))
1267 print_generic_expr (stderr
, var
, TDF_SLIM
);
1268 fprintf (stderr
, " is defined ");
1270 fprintf (stderr
, " in BB%d, ", tmp
->index
);
1271 fprintf (stderr
, "by:\n");
1272 print_gimple_stmt (stderr
, stmt
, 0, TDF_SLIM
);
1273 fprintf (stderr
, "\nIt is also live-on-entry to entry BB %d",
1275 fprintf (stderr
, " So it appears to have multiple defs.\n");
1282 print_generic_expr (stderr
, var
, TDF_SLIM
);
1283 fprintf (stderr
, " is live-on-entry to BB%d ",
1287 fprintf (stderr
, " but is not the default def of ");
1288 print_generic_expr (stderr
, d
, TDF_SLIM
);
1289 fprintf (stderr
, "\n");
1292 fprintf (stderr
, " and there is no default def.\n");
1299 /* The only way this var shouldn't be marked live on entry is
1300 if it occurs in a PHI argument of the block. */
1303 gimple_stmt_iterator gsi
;
1304 for (gsi
= gsi_start_phis (e
->dest
);
1305 !gsi_end_p (gsi
) && !ok
;
1308 gimple phi
= gsi_stmt (gsi
);
1309 for (z
= 0; z
< gimple_phi_num_args (phi
); z
++)
1310 if (var
== gimple_phi_arg_def (phi
, z
))
1319 print_generic_expr (stderr
, var
, TDF_SLIM
);
1320 fprintf (stderr
, " is not marked live-on-entry to entry BB%d ",
1322 fprintf (stderr
, "but it is a default def so it should be.\n");
1326 gcc_assert (num
<= 0);