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 decl_to_index
= htab_create (num_part
, tree_decl_map_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 var
= SSA_NAME_VAR (var
);
86 /* If base variable hasn't been seen, set it up. */
88 slot
= (struct tree_int_map
**) htab_find_slot (decl_to_index
, m
, INSERT
);
91 baseindex
= m
- mapstorage
;
97 baseindex
= (*slot
)->to
;
98 map
->partition_to_base_index
[x
] = baseindex
;
101 map
->num_basevars
= m
- mapstorage
;
104 htab_delete (decl_to_index
);
108 /* Remove the base table in MAP. */
111 var_map_base_fini (var_map map
)
113 /* Free the basevar info if it is present. */
114 if (map
->partition_to_base_index
!= NULL
)
116 free (map
->partition_to_base_index
);
117 map
->partition_to_base_index
= NULL
;
118 map
->num_basevars
= 0;
121 /* Create a variable partition map of SIZE, initialize and return it. */
124 init_var_map (int size
)
128 map
= (var_map
) xmalloc (sizeof (struct _var_map
));
129 map
->var_partition
= partition_new (size
);
131 map
->partition_to_view
= NULL
;
132 map
->view_to_partition
= NULL
;
133 map
->num_partitions
= size
;
134 map
->partition_size
= size
;
135 map
->num_basevars
= 0;
136 map
->partition_to_base_index
= NULL
;
141 /* Free memory associated with MAP. */
144 delete_var_map (var_map map
)
146 var_map_base_fini (map
);
147 partition_delete (map
->var_partition
);
148 free (map
->partition_to_view
);
149 free (map
->view_to_partition
);
154 /* This function will combine the partitions in MAP for VAR1 and VAR2. It
155 Returns the partition which represents the new partition. If the two
156 partitions cannot be combined, NO_PARTITION is returned. */
159 var_union (var_map map
, tree var1
, tree var2
)
163 gcc_assert (TREE_CODE (var1
) == SSA_NAME
);
164 gcc_assert (TREE_CODE (var2
) == SSA_NAME
);
166 /* This is independent of partition_to_view. If partition_to_view is
167 on, then whichever one of these partitions is absorbed will never have a
168 dereference into the partition_to_view array any more. */
170 p1
= partition_find (map
->var_partition
, SSA_NAME_VERSION (var1
));
171 p2
= partition_find (map
->var_partition
, SSA_NAME_VERSION (var2
));
173 gcc_assert (p1
!= NO_PARTITION
);
174 gcc_assert (p2
!= NO_PARTITION
);
179 p3
= partition_union (map
->var_partition
, p1
, p2
);
181 if (map
->partition_to_view
)
182 p3
= map
->partition_to_view
[p3
];
188 /* Compress the partition numbers in MAP such that they fall in the range
189 0..(num_partitions-1) instead of wherever they turned out during
190 the partitioning exercise. This removes any references to unused
191 partitions, thereby allowing bitmaps and other vectors to be much
194 This is implemented such that compaction doesn't affect partitioning.
195 Ie., once partitions are created and possibly merged, running one
196 or more different kind of compaction will not affect the partitions
197 themselves. Their index might change, but all the same variables will
198 still be members of the same partition group. This allows work on reduced
199 sets, and no loss of information when a larger set is later desired.
201 In particular, coalescing can work on partitions which have 2 or more
202 definitions, and then 'recompact' later to include all the single
203 definitions for assignment to program variables. */
206 /* Set MAP back to the initial state of having no partition view. Return a
207 bitmap which has a bit set for each partition number which is in use in the
211 partition_view_init (var_map map
)
217 used
= BITMAP_ALLOC (NULL
);
219 /* Already in a view? Abandon the old one. */
220 if (map
->partition_to_view
)
222 free (map
->partition_to_view
);
223 map
->partition_to_view
= NULL
;
225 if (map
->view_to_partition
)
227 free (map
->view_to_partition
);
228 map
->view_to_partition
= NULL
;
231 /* Find out which partitions are actually referenced. */
232 for (x
= 0; x
< map
->partition_size
; x
++)
234 tmp
= partition_find (map
->var_partition
, x
);
235 if (ssa_name (tmp
) != NULL_TREE
&& is_gimple_reg (ssa_name (tmp
))
236 && (!has_zero_uses (ssa_name (tmp
))
237 || !SSA_NAME_IS_DEFAULT_DEF (ssa_name (tmp
))))
238 bitmap_set_bit (used
, tmp
);
241 map
->num_partitions
= map
->partition_size
;
246 /* This routine will finalize the view data for MAP based on the partitions
247 set in SELECTED. This is either the same bitmap returned from
248 partition_view_init, or a trimmed down version if some of those partitions
249 were not desired in this view. SELECTED is freed before returning. */
252 partition_view_fini (var_map map
, bitmap selected
)
255 unsigned count
, i
, x
, limit
;
257 gcc_assert (selected
);
259 count
= bitmap_count_bits (selected
);
260 limit
= map
->partition_size
;
262 /* If its a one-to-one ratio, we don't need any view compaction. */
265 map
->partition_to_view
= (int *)xmalloc (limit
* sizeof (int));
266 memset (map
->partition_to_view
, 0xff, (limit
* sizeof (int)));
267 map
->view_to_partition
= (int *)xmalloc (count
* sizeof (int));
270 /* Give each selected partition an index. */
271 EXECUTE_IF_SET_IN_BITMAP (selected
, 0, x
, bi
)
273 map
->partition_to_view
[x
] = i
;
274 map
->view_to_partition
[i
] = x
;
277 gcc_assert (i
== count
);
278 map
->num_partitions
= i
;
281 BITMAP_FREE (selected
);
285 /* Create a partition view which includes all the used partitions in MAP. If
286 WANT_BASES is true, create the base variable map as well. */
289 partition_view_normal (var_map map
, bool want_bases
)
293 used
= partition_view_init (map
);
294 partition_view_fini (map
, used
);
297 var_map_base_init (map
);
299 var_map_base_fini (map
);
303 /* Create a partition view in MAP which includes just partitions which occur in
304 the bitmap ONLY. If WANT_BASES is true, create the base variable map
308 partition_view_bitmap (var_map map
, bitmap only
, bool want_bases
)
311 bitmap new_partitions
= BITMAP_ALLOC (NULL
);
315 used
= partition_view_init (map
);
316 EXECUTE_IF_SET_IN_BITMAP (only
, 0, x
, bi
)
318 p
= partition_find (map
->var_partition
, x
);
319 gcc_assert (bitmap_bit_p (used
, p
));
320 bitmap_set_bit (new_partitions
, p
);
322 partition_view_fini (map
, new_partitions
);
326 var_map_base_init (map
);
328 var_map_base_fini (map
);
332 static bitmap usedvars
;
334 /* Mark VAR as used, so that it'll be preserved during rtl expansion.
335 Returns true if VAR wasn't marked before. */
338 set_is_used (tree var
)
340 return bitmap_set_bit (usedvars
, DECL_UID (var
));
343 /* Return true if VAR is marked as used. */
348 return bitmap_bit_p (usedvars
, DECL_UID (var
));
351 static inline void mark_all_vars_used (tree
*);
353 /* Helper function for mark_all_vars_used, called via walk_tree. */
356 mark_all_vars_used_1 (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
359 enum tree_code_class c
= TREE_CODE_CLASS (TREE_CODE (t
));
362 if (TREE_CODE (t
) == SSA_NAME
)
363 t
= SSA_NAME_VAR (t
);
365 if (IS_EXPR_CODE_CLASS (c
)
366 && (b
= TREE_BLOCK (t
)) != NULL
)
367 TREE_USED (b
) = true;
369 /* Ignore TMR_OFFSET and TMR_STEP for TARGET_MEM_REFS, as those
370 fields do not contain vars. */
371 if (TREE_CODE (t
) == TARGET_MEM_REF
)
373 mark_all_vars_used (&TMR_BASE (t
));
374 mark_all_vars_used (&TMR_INDEX (t
));
375 mark_all_vars_used (&TMR_INDEX2 (t
));
380 /* Only need to mark VAR_DECLS; parameters and return results are not
381 eliminated as unused. */
382 if (TREE_CODE (t
) == VAR_DECL
)
384 /* When a global var becomes used for the first time also walk its
385 initializer (non global ones don't have any). */
386 if (set_is_used (t
) && is_global_var (t
))
387 mark_all_vars_used (&DECL_INITIAL (t
));
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 else if (DECL_IGNORED_P (*t
))
464 *t
= DECL_CHAIN (*t
);
468 /* When we are outputting debug info, we usually want to output
469 info about optimized-out variables in the scope blocks.
470 Exception are the scope blocks not containing any instructions
471 at all so user can't get into the scopes at first place. */
472 else if (is_used_p (*t
))
474 else if (TREE_CODE (*t
) == LABEL_DECL
&& TREE_USED (*t
))
475 /* For labels that are still used in the IL, the decision to
476 preserve them must not depend DEBUG_INFO_LEVEL, otherwise we
477 risk having different ordering in debug vs. non-debug builds
478 during inlining or versioning.
479 A label appearing here (we have already checked DECL_IGNORED_P)
480 should not be used in the IL unless it has been explicitly used
481 before, so we use TREE_USED as an approximation. */
482 /* In principle, we should do the same here as for the debug case
483 below, however, when debugging, there might be additional nested
484 levels that keep an upper level with a label live, so we have to
485 force this block to be considered used, too. */
488 /* When we are not doing full debug info, we however can keep around
489 only the used variables for cfgexpand's memory packing saving quite
492 For sake of -g3, we keep around those vars but we don't count this as
493 use of block, so innermost block with no used vars and no instructions
494 can be considered dead. We only want to keep around blocks user can
495 breakpoint into and ask about value of optimized out variables.
497 Similarly we need to keep around types at least until all
498 variables of all nested blocks are gone. We track no
499 information on whether given type is used or not, so we have
500 to keep them even when not emitting debug information,
501 otherwise we may end up remapping variables and their (local)
502 types in different orders depending on whether debug
503 information is being generated. */
505 else if (TREE_CODE (*t
) == TYPE_DECL
506 || debug_info_level
== DINFO_LEVEL_NORMAL
507 || debug_info_level
== DINFO_LEVEL_VERBOSE
)
511 *t
= DECL_CHAIN (*t
);
516 for (t
= &BLOCK_SUBBLOCKS (scope
); *t
;)
517 if (remove_unused_scope_block_p (*t
))
519 if (BLOCK_SUBBLOCKS (*t
))
521 tree next
= BLOCK_CHAIN (*t
);
522 tree supercontext
= BLOCK_SUPERCONTEXT (*t
);
524 *t
= BLOCK_SUBBLOCKS (*t
);
525 while (BLOCK_CHAIN (*t
))
527 BLOCK_SUPERCONTEXT (*t
) = supercontext
;
528 t
= &BLOCK_CHAIN (*t
);
530 BLOCK_CHAIN (*t
) = next
;
531 BLOCK_SUPERCONTEXT (*t
) = supercontext
;
532 t
= &BLOCK_CHAIN (*t
);
536 *t
= BLOCK_CHAIN (*t
);
540 t
= &BLOCK_CHAIN (*t
);
547 /* Outer scope is always used. */
548 else if (!BLOCK_SUPERCONTEXT (scope
)
549 || TREE_CODE (BLOCK_SUPERCONTEXT (scope
)) == FUNCTION_DECL
)
551 /* Innermost blocks with no live variables nor statements can be always
553 else if (!nsubblocks
)
555 /* For terse debug info we can eliminate info on unused variables. */
556 else if (debug_info_level
== DINFO_LEVEL_NONE
557 || debug_info_level
== DINFO_LEVEL_TERSE
)
559 /* Even for -g0/-g1 don't prune outer scopes from artificial
560 functions, otherwise diagnostics using tree_nonartificial_location
561 will not be emitted properly. */
562 if (inlined_function_outer_scope_p (scope
))
567 && TREE_CODE (ao
) == BLOCK
568 && BLOCK_ABSTRACT_ORIGIN (ao
) != ao
)
569 ao
= BLOCK_ABSTRACT_ORIGIN (ao
);
571 && TREE_CODE (ao
) == FUNCTION_DECL
572 && DECL_DECLARED_INLINE_P (ao
)
573 && lookup_attribute ("artificial", DECL_ATTRIBUTES (ao
)))
577 else if (BLOCK_VARS (scope
) || BLOCK_NUM_NONLOCALIZED_VARS (scope
))
579 /* See if this block is important for representation of inlined function.
580 Inlined functions are always represented by block with
581 block_ultimate_origin being set to FUNCTION_DECL and DECL_SOURCE_LOCATION
583 else if (inlined_function_outer_scope_p (scope
))
586 /* Verfify that only blocks with source location set
587 are entry points to the inlined functions. */
588 gcc_assert (BLOCK_SOURCE_LOCATION (scope
) == UNKNOWN_LOCATION
);
590 TREE_USED (scope
) = !unused
;
594 /* Mark all VAR_DECLS under *EXPR_P as used, so that they won't be
595 eliminated during the tree->rtl conversion process. */
598 mark_all_vars_used (tree
*expr_p
)
600 walk_tree (expr_p
, mark_all_vars_used_1
, NULL
, NULL
);
604 /* Dump scope blocks starting at SCOPE to FILE. INDENT is the
605 indentation level and FLAGS is as in print_generic_expr. */
608 dump_scope_block (FILE *file
, int indent
, tree scope
, int flags
)
613 fprintf (file
, "\n%*s{ Scope block #%i%s%s",indent
, "" , BLOCK_NUMBER (scope
),
614 TREE_USED (scope
) ? "" : " (unused)",
615 BLOCK_ABSTRACT (scope
) ? " (abstract)": "");
616 if (BLOCK_SOURCE_LOCATION (scope
) != UNKNOWN_LOCATION
)
618 expanded_location s
= expand_location (BLOCK_SOURCE_LOCATION (scope
));
619 fprintf (file
, " %s:%i", s
.file
, s
.line
);
621 if (BLOCK_ABSTRACT_ORIGIN (scope
))
623 tree origin
= block_ultimate_origin (scope
);
626 fprintf (file
, " Originating from :");
628 print_generic_decl (file
, origin
, flags
);
630 fprintf (file
, "#%i", BLOCK_NUMBER (origin
));
633 fprintf (file
, " \n");
634 for (var
= BLOCK_VARS (scope
); var
; var
= DECL_CHAIN (var
))
636 fprintf (file
, "%*s", indent
, "");
637 print_generic_decl (file
, var
, flags
);
638 fprintf (file
, "\n");
640 for (i
= 0; i
< BLOCK_NUM_NONLOCALIZED_VARS (scope
); i
++)
642 fprintf (file
, "%*s",indent
, "");
643 print_generic_decl (file
, BLOCK_NONLOCALIZED_VAR (scope
, i
),
645 fprintf (file
, " (nonlocalized)\n");
647 for (t
= BLOCK_SUBBLOCKS (scope
); t
; t
= BLOCK_CHAIN (t
))
648 dump_scope_block (file
, indent
+ 2, t
, flags
);
649 fprintf (file
, "\n%*s}\n",indent
, "");
652 /* Dump the tree of lexical scopes starting at SCOPE to stderr. FLAGS
653 is as in print_generic_expr. */
656 debug_scope_block (tree scope
, int flags
)
658 dump_scope_block (stderr
, 0, scope
, flags
);
662 /* Dump the tree of lexical scopes of current_function_decl to FILE.
663 FLAGS is as in print_generic_expr. */
666 dump_scope_blocks (FILE *file
, int flags
)
668 dump_scope_block (file
, 0, DECL_INITIAL (current_function_decl
), flags
);
672 /* Dump the tree of lexical scopes of current_function_decl to stderr.
673 FLAGS is as in print_generic_expr. */
676 debug_scope_blocks (int flags
)
678 dump_scope_blocks (stderr
, flags
);
681 /* Remove local variables that are not referenced in the IL. */
684 remove_unused_locals (void)
688 unsigned srcidx
, dstidx
, num
;
689 bool have_local_clobbers
= false;
691 /* Removing declarations from lexical blocks when not optimizing is
692 not only a waste of time, it actually causes differences in stack
697 timevar_push (TV_REMOVE_UNUSED
);
699 mark_scope_block_unused (DECL_INITIAL (current_function_decl
));
701 usedvars
= BITMAP_ALLOC (NULL
);
703 /* Walk the CFG marking all referenced symbols. */
706 gimple_stmt_iterator gsi
;
711 /* Walk the statements. */
712 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
714 gimple stmt
= gsi_stmt (gsi
);
715 tree b
= gimple_block (stmt
);
717 if (is_gimple_debug (stmt
))
720 if (gimple_clobber_p (stmt
))
722 have_local_clobbers
= true;
727 TREE_USED (b
) = true;
729 for (i
= 0; i
< gimple_num_ops (stmt
); i
++)
730 mark_all_vars_used (gimple_op_ptr (gsi_stmt (gsi
), i
));
733 for (gsi
= gsi_start_phis (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
738 gimple phi
= gsi_stmt (gsi
);
740 if (!is_gimple_reg (gimple_phi_result (phi
)))
743 def
= gimple_phi_result (phi
);
744 mark_all_vars_used (&def
);
746 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_ALL_USES
)
748 tree arg
= USE_FROM_PTR (arg_p
);
749 mark_all_vars_used (&arg
);
753 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
755 TREE_USED (e
->goto_block
) = true;
758 /* We do a two-pass approach about the out-of-scope clobbers. We want
759 to remove them if they are the only references to a local variable,
760 but we want to retain them when there's any other. So the first pass
761 ignores them, and the second pass (if there were any) tries to remove
763 if (have_local_clobbers
)
766 gimple_stmt_iterator gsi
;
768 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
);)
770 gimple stmt
= gsi_stmt (gsi
);
771 tree b
= gimple_block (stmt
);
773 if (gimple_clobber_p (stmt
))
775 tree lhs
= gimple_assign_lhs (stmt
);
776 if (TREE_CODE (lhs
) == VAR_DECL
&& !is_used_p (lhs
))
778 unlink_stmt_vdef (stmt
);
779 gsi_remove (&gsi
, true);
784 TREE_USED (b
) = true;
790 cfun
->has_local_explicit_reg_vars
= false;
792 /* Remove unmarked local and global vars from local_decls. */
793 num
= VEC_length (tree
, cfun
->local_decls
);
794 for (srcidx
= 0, dstidx
= 0; srcidx
< num
; srcidx
++)
796 var
= VEC_index (tree
, cfun
->local_decls
, srcidx
);
797 if (TREE_CODE (var
) == VAR_DECL
)
799 if (!is_used_p (var
))
802 if (cfun
->nonlocal_goto_save_area
803 && TREE_OPERAND (cfun
->nonlocal_goto_save_area
, 0) == var
)
804 cfun
->nonlocal_goto_save_area
= NULL
;
805 /* Release any default def associated with var. */
806 if ((def
= ssa_default_def (cfun
, var
)) != NULL_TREE
)
808 set_ssa_default_def (cfun
, var
, NULL_TREE
);
809 release_ssa_name (def
);
814 if (TREE_CODE (var
) == VAR_DECL
815 && DECL_HARD_REGISTER (var
)
816 && !is_global_var (var
))
817 cfun
->has_local_explicit_reg_vars
= true;
819 if (srcidx
!= dstidx
)
820 VEC_replace (tree
, cfun
->local_decls
, dstidx
, var
);
824 VEC_truncate (tree
, cfun
->local_decls
, dstidx
);
826 remove_unused_scope_block_p (DECL_INITIAL (current_function_decl
));
828 BITMAP_FREE (usedvars
);
830 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
832 fprintf (dump_file
, "Scope blocks after cleanups:\n");
833 dump_scope_blocks (dump_file
, dump_flags
);
836 timevar_pop (TV_REMOVE_UNUSED
);
840 /* Allocate and return a new live range information object base on MAP. */
842 static tree_live_info_p
843 new_tree_live_info (var_map map
)
845 tree_live_info_p live
;
848 live
= (tree_live_info_p
) xmalloc (sizeof (struct tree_live_info_d
));
850 live
->num_blocks
= last_basic_block
;
852 live
->livein
= (bitmap
*)xmalloc (last_basic_block
* sizeof (bitmap
));
853 for (x
= 0; x
< (unsigned)last_basic_block
; x
++)
854 live
->livein
[x
] = BITMAP_ALLOC (NULL
);
856 live
->liveout
= (bitmap
*)xmalloc (last_basic_block
* sizeof (bitmap
));
857 for (x
= 0; x
< (unsigned)last_basic_block
; x
++)
858 live
->liveout
[x
] = BITMAP_ALLOC (NULL
);
860 live
->work_stack
= XNEWVEC (int, last_basic_block
);
861 live
->stack_top
= live
->work_stack
;
863 live
->global
= BITMAP_ALLOC (NULL
);
868 /* Free storage for live range info object LIVE. */
871 delete_tree_live_info (tree_live_info_p live
)
875 BITMAP_FREE (live
->global
);
876 free (live
->work_stack
);
878 for (x
= live
->num_blocks
- 1; x
>= 0; x
--)
879 BITMAP_FREE (live
->liveout
[x
]);
880 free (live
->liveout
);
882 for (x
= live
->num_blocks
- 1; x
>= 0; x
--)
883 BITMAP_FREE (live
->livein
[x
]);
890 /* Visit basic block BB and propagate any required live on entry bits from
891 LIVE into the predecessors. VISITED is the bitmap of visited blocks.
892 TMP is a temporary work bitmap which is passed in to avoid reallocating
896 loe_visit_block (tree_live_info_p live
, basic_block bb
, sbitmap visited
,
904 gcc_assert (!TEST_BIT (visited
, bb
->index
));
906 SET_BIT (visited
, bb
->index
);
907 loe
= live_on_entry (live
, bb
);
909 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
912 if (pred_bb
== ENTRY_BLOCK_PTR
)
914 /* TMP is variables live-on-entry from BB that aren't defined in the
915 predecessor block. This should be the live on entry vars to pred.
916 Note that liveout is the DEFs in a block while live on entry is
918 bitmap_and_compl (tmp
, loe
, live
->liveout
[pred_bb
->index
]);
920 /* Add these bits to live-on-entry for the pred. if there are any
921 changes, and pred_bb has been visited already, add it to the
923 change
= bitmap_ior_into (live_on_entry (live
, pred_bb
), tmp
);
924 if (TEST_BIT (visited
, pred_bb
->index
) && change
)
926 RESET_BIT (visited
, pred_bb
->index
);
927 *(live
->stack_top
)++ = pred_bb
->index
;
933 /* Using LIVE, fill in all the live-on-entry blocks between the defs and uses
934 of all the variables. */
937 live_worklist (tree_live_info_p live
)
941 sbitmap visited
= sbitmap_alloc (last_basic_block
+ 1);
942 bitmap tmp
= BITMAP_ALLOC (NULL
);
944 sbitmap_zero (visited
);
946 /* Visit all the blocks in reverse order and propagate live on entry values
947 into the predecessors blocks. */
948 FOR_EACH_BB_REVERSE (bb
)
949 loe_visit_block (live
, bb
, visited
, tmp
);
951 /* Process any blocks which require further iteration. */
952 while (live
->stack_top
!= live
->work_stack
)
954 b
= *--(live
->stack_top
);
955 loe_visit_block (live
, BASIC_BLOCK (b
), visited
, tmp
);
959 sbitmap_free (visited
);
963 /* Calculate the initial live on entry vector for SSA_NAME using immediate_use
964 links. Set the live on entry fields in LIVE. Def's are marked temporarily
965 in the liveout vector. */
968 set_var_live_on_entry (tree ssa_name
, tree_live_info_p live
)
973 basic_block def_bb
= NULL
;
974 imm_use_iterator imm_iter
;
977 p
= var_to_partition (live
->map
, ssa_name
);
978 if (p
== NO_PARTITION
)
981 stmt
= SSA_NAME_DEF_STMT (ssa_name
);
984 def_bb
= gimple_bb (stmt
);
985 /* Mark defs in liveout bitmap temporarily. */
987 bitmap_set_bit (live
->liveout
[def_bb
->index
], p
);
990 def_bb
= ENTRY_BLOCK_PTR
;
992 /* Visit each use of SSA_NAME and if it isn't in the same block as the def,
993 add it to the list of live on entry blocks. */
994 FOR_EACH_IMM_USE_FAST (use
, imm_iter
, ssa_name
)
996 gimple use_stmt
= USE_STMT (use
);
997 basic_block add_block
= NULL
;
999 if (gimple_code (use_stmt
) == GIMPLE_PHI
)
1001 /* Uses in PHI's are considered to be live at exit of the SRC block
1002 as this is where a copy would be inserted. Check to see if it is
1003 defined in that block, or whether its live on entry. */
1004 int index
= PHI_ARG_INDEX_FROM_USE (use
);
1005 edge e
= gimple_phi_arg_edge (use_stmt
, index
);
1006 if (e
->src
!= ENTRY_BLOCK_PTR
)
1008 if (e
->src
!= def_bb
)
1012 else if (is_gimple_debug (use_stmt
))
1016 /* If its not defined in this block, its live on entry. */
1017 basic_block use_bb
= gimple_bb (use_stmt
);
1018 if (use_bb
!= def_bb
)
1022 /* If there was a live on entry use, set the bit. */
1026 bitmap_set_bit (live
->livein
[add_block
->index
], p
);
1030 /* If SSA_NAME is live on entry to at least one block, fill in all the live
1031 on entry blocks between the def and all the uses. */
1033 bitmap_set_bit (live
->global
, p
);
1037 /* Calculate the live on exit vectors based on the entry info in LIVEINFO. */
1040 calculate_live_on_exit (tree_live_info_p liveinfo
)
1046 /* live on entry calculations used liveout vectors for defs, clear them. */
1048 bitmap_clear (liveinfo
->liveout
[bb
->index
]);
1050 /* Set all the live-on-exit bits for uses in PHIs. */
1053 gimple_stmt_iterator gsi
;
1056 /* Mark the PHI arguments which are live on exit to the pred block. */
1057 for (gsi
= gsi_start_phis (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1059 gimple phi
= gsi_stmt (gsi
);
1060 for (i
= 0; i
< gimple_phi_num_args (phi
); i
++)
1062 tree t
= PHI_ARG_DEF (phi
, i
);
1065 if (TREE_CODE (t
) != SSA_NAME
)
1068 p
= var_to_partition (liveinfo
->map
, t
);
1069 if (p
== NO_PARTITION
)
1071 e
= gimple_phi_arg_edge (phi
, i
);
1072 if (e
->src
!= ENTRY_BLOCK_PTR
)
1073 bitmap_set_bit (liveinfo
->liveout
[e
->src
->index
], p
);
1077 /* Add each successors live on entry to this bock live on exit. */
1078 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1079 if (e
->dest
!= EXIT_BLOCK_PTR
)
1080 bitmap_ior_into (liveinfo
->liveout
[bb
->index
],
1081 live_on_entry (liveinfo
, e
->dest
));
1086 /* Given partition map MAP, calculate all the live on entry bitmaps for
1087 each partition. Return a new live info object. */
1090 calculate_live_ranges (var_map map
)
1094 tree_live_info_p live
;
1096 live
= new_tree_live_info (map
);
1097 for (i
= 0; i
< num_var_partitions (map
); i
++)
1099 var
= partition_to_var (map
, i
);
1100 if (var
!= NULL_TREE
)
1101 set_var_live_on_entry (var
, live
);
1104 live_worklist (live
);
1106 #ifdef ENABLE_CHECKING
1107 verify_live_on_entry (live
);
1110 calculate_live_on_exit (live
);
1115 /* Output partition map MAP to file F. */
1118 dump_var_map (FILE *f
, var_map map
)
1124 fprintf (f
, "\nPartition map \n\n");
1126 for (x
= 0; x
< map
->num_partitions
; x
++)
1128 if (map
->view_to_partition
!= NULL
)
1129 p
= map
->view_to_partition
[x
];
1133 if (ssa_name (p
) == NULL_TREE
)
1137 for (y
= 1; y
< num_ssa_names
; y
++)
1139 p
= partition_find (map
->var_partition
, y
);
1140 if (map
->partition_to_view
)
1141 p
= map
->partition_to_view
[p
];
1146 fprintf(f
, "Partition %d (", x
);
1147 print_generic_expr (f
, partition_to_var (map
, p
), TDF_SLIM
);
1150 fprintf (f
, "%d ", y
);
1160 /* Output live range info LIVE to file F, controlled by FLAG. */
1163 dump_live_info (FILE *f
, tree_live_info_p live
, int flag
)
1167 var_map map
= live
->map
;
1170 if ((flag
& LIVEDUMP_ENTRY
) && live
->livein
)
1174 fprintf (f
, "\nLive on entry to BB%d : ", bb
->index
);
1175 EXECUTE_IF_SET_IN_BITMAP (live
->livein
[bb
->index
], 0, i
, bi
)
1177 print_generic_expr (f
, partition_to_var (map
, i
), TDF_SLIM
);
1184 if ((flag
& LIVEDUMP_EXIT
) && live
->liveout
)
1188 fprintf (f
, "\nLive on exit from BB%d : ", bb
->index
);
1189 EXECUTE_IF_SET_IN_BITMAP (live
->liveout
[bb
->index
], 0, i
, bi
)
1191 print_generic_expr (f
, partition_to_var (map
, i
), TDF_SLIM
);
1199 #ifdef ENABLE_CHECKING
1200 /* Verify that SSA_VAR is a non-virtual SSA_NAME. */
1203 register_ssa_partition_check (tree ssa_var
)
1205 gcc_assert (TREE_CODE (ssa_var
) == SSA_NAME
);
1206 if (!is_gimple_reg (ssa_var
))
1208 fprintf (stderr
, "Illegally registering a virtual SSA name :");
1209 print_generic_expr (stderr
, ssa_var
, TDF_SLIM
);
1210 fprintf (stderr
, " in the SSA->Normal phase.\n");
1211 internal_error ("SSA corruption");
1216 /* Verify that the info in LIVE matches the current cfg. */
1219 verify_live_on_entry (tree_live_info_p live
)
1228 var_map map
= live
->map
;
1230 /* Check for live on entry partitions and report those with a DEF in
1231 the program. This will typically mean an optimization has done
1233 bb
= ENTRY_BLOCK_PTR
;
1235 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1237 int entry_block
= e
->dest
->index
;
1238 if (e
->dest
== EXIT_BLOCK_PTR
)
1240 for (i
= 0; i
< (unsigned)num_var_partitions (map
); i
++)
1245 var
= partition_to_var (map
, i
);
1246 stmt
= SSA_NAME_DEF_STMT (var
);
1247 tmp
= gimple_bb (stmt
);
1248 d
= ssa_default_def (cfun
, SSA_NAME_VAR (var
));
1250 loe
= live_on_entry (live
, e
->dest
);
1251 if (loe
&& bitmap_bit_p (loe
, i
))
1253 if (!gimple_nop_p (stmt
))
1256 print_generic_expr (stderr
, var
, TDF_SLIM
);
1257 fprintf (stderr
, " is defined ");
1259 fprintf (stderr
, " in BB%d, ", tmp
->index
);
1260 fprintf (stderr
, "by:\n");
1261 print_gimple_stmt (stderr
, stmt
, 0, TDF_SLIM
);
1262 fprintf (stderr
, "\nIt is also live-on-entry to entry BB %d",
1264 fprintf (stderr
, " So it appears to have multiple defs.\n");
1271 print_generic_expr (stderr
, var
, TDF_SLIM
);
1272 fprintf (stderr
, " is live-on-entry to BB%d ",
1276 fprintf (stderr
, " but is not the default def of ");
1277 print_generic_expr (stderr
, d
, TDF_SLIM
);
1278 fprintf (stderr
, "\n");
1281 fprintf (stderr
, " and there is no default def.\n");
1288 /* The only way this var shouldn't be marked live on entry is
1289 if it occurs in a PHI argument of the block. */
1292 gimple_stmt_iterator gsi
;
1293 for (gsi
= gsi_start_phis (e
->dest
);
1294 !gsi_end_p (gsi
) && !ok
;
1297 gimple phi
= gsi_stmt (gsi
);
1298 for (z
= 0; z
< gimple_phi_num_args (phi
); z
++)
1299 if (var
== gimple_phi_arg_def (phi
, z
))
1308 print_generic_expr (stderr
, var
, TDF_SLIM
);
1309 fprintf (stderr
, " is not marked live-on-entry to entry BB%d ",
1311 fprintf (stderr
, "but it is a default def so it should be.\n");
1315 gcc_assert (num
<= 0);