1 /* Data flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008 Free Software
4 Contributed by Diego Novillo <dnovillo@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 "pointer-set.h"
31 #include "hard-reg-set.h"
32 #include "basic-block.h"
37 #include "langhooks.h"
40 #include "diagnostic.h"
41 #include "tree-dump.h"
42 #include "tree-gimple.h"
43 #include "tree-flow.h"
44 #include "tree-inline.h"
45 #include "tree-pass.h"
50 /* Build and maintain data flow information for trees. */
52 /* Counters used to display DFA and SSA statistics. */
67 /* Local functions. */
68 static void collect_dfa_stats (struct dfa_stats_d
*);
69 static tree
collect_dfa_stats_r (tree
*, int *, void *);
70 static tree
find_vars_r (tree
*, int *, void *);
73 /*---------------------------------------------------------------------------
74 Dataflow analysis (DFA) routines
75 ---------------------------------------------------------------------------*/
76 /* Find all the variables referenced in the function. This function
77 builds the global arrays REFERENCED_VARS and CALL_CLOBBERED_VARS.
79 Note that this function does not look for statement operands, it simply
80 determines what variables are referenced in the program and detects
81 various attributes for each variable used by alias analysis and the
85 find_referenced_vars (void)
88 block_stmt_iterator si
;
93 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
95 tree
*stmt_p
= bsi_stmt_ptr (si
);
96 walk_tree (stmt_p
, find_vars_r
, NULL
, NULL
);
99 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
101 int len
= PHI_NUM_ARGS (phi
);
104 walk_tree (&phi
, find_vars_r
, NULL
, NULL
);
106 for (i
= 0; i
< len
; i
++)
108 tree arg
= PHI_ARG_DEF (phi
, i
);
109 walk_tree (&arg
, find_vars_r
, NULL
, NULL
);
117 struct gimple_opt_pass pass_referenced_vars
=
123 find_referenced_vars
, /* execute */
126 0, /* static_pass_number */
127 TV_FIND_REFERENCED_VARS
, /* tv_id */
128 PROP_gimple_leh
| PROP_cfg
, /* properties_required */
129 PROP_referenced_vars
, /* properties_provided */
130 0, /* properties_destroyed */
131 TODO_dump_func
, /* todo_flags_start */
132 TODO_dump_func
/* todo_flags_finish */
137 /*---------------------------------------------------------------------------
139 ---------------------------------------------------------------------------*/
140 /* Create a new annotation for a _DECL node T. */
143 create_var_ann (tree t
)
148 gcc_assert (DECL_P (t
));
149 gcc_assert (!t
->base
.ann
|| t
->base
.ann
->common
.type
== VAR_ANN
);
151 ann
= GGC_CNEW (struct var_ann_d
);
152 ann
->common
.type
= VAR_ANN
;
153 t
->base
.ann
= (tree_ann_t
) ann
;
158 /* Create a new annotation for a FUNCTION_DECL node T. */
161 create_function_ann (tree t
)
166 gcc_assert (TREE_CODE (t
) == FUNCTION_DECL
);
167 gcc_assert (!t
->base
.ann
|| t
->base
.ann
->common
.type
== FUNCTION_ANN
);
169 ann
= (function_ann_t
) ggc_alloc (sizeof (*ann
));
170 memset ((void *) ann
, 0, sizeof (*ann
));
172 ann
->common
.type
= FUNCTION_ANN
;
174 t
->base
.ann
= (tree_ann_t
) ann
;
179 /* Create a new annotation for a statement node T. */
182 create_stmt_ann (tree t
)
186 gcc_assert (is_gimple_stmt (t
));
187 gcc_assert (!t
->base
.ann
|| t
->base
.ann
->common
.type
== STMT_ANN
);
189 ann
= GGC_CNEW (struct stmt_ann_d
);
191 ann
->common
.type
= STMT_ANN
;
193 /* Since we just created the annotation, mark the statement modified. */
194 ann
->modified
= true;
196 ann
->uid
= inc_gimple_stmt_max_uid (cfun
);
197 t
->base
.ann
= (tree_ann_t
) ann
;
202 /* Renumber all of the gimple stmt uids. */
205 renumber_gimple_stmt_uids (void)
209 set_gimple_stmt_max_uid (cfun
, 0);
212 block_stmt_iterator bsi
;
213 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
215 tree stmt
= bsi_stmt (bsi
);
216 /* If the stmt has an annotation, then overwrite it, if not,
217 the process of getting it will set the number
219 if (has_stmt_ann (stmt
))
220 set_gimple_stmt_uid (stmt
, inc_gimple_stmt_max_uid (cfun
));
227 /* Create a new annotation for a tree T. */
230 create_tree_common_ann (tree t
)
232 tree_ann_common_t ann
;
235 gcc_assert (!t
->base
.ann
|| t
->base
.ann
->common
.type
== TREE_ANN_COMMON
);
237 ann
= GGC_CNEW (struct tree_ann_common_d
);
239 ann
->type
= TREE_ANN_COMMON
;
240 t
->base
.ann
= (tree_ann_t
) ann
;
245 /* Build a temporary. Make sure and register it to be renamed. */
248 make_rename_temp (tree type
, const char *prefix
)
250 tree t
= create_tmp_var (type
, prefix
);
252 if (TREE_CODE (TREE_TYPE (t
)) == COMPLEX_TYPE
253 || TREE_CODE (TREE_TYPE (t
)) == VECTOR_TYPE
)
254 DECL_GIMPLE_REG_P (t
) = 1;
256 if (gimple_referenced_vars (cfun
))
258 add_referenced_var (t
);
259 mark_sym_for_renaming (t
);
267 /*---------------------------------------------------------------------------
269 ---------------------------------------------------------------------------*/
270 /* Dump the list of all the referenced variables in the current function to
274 dump_referenced_vars (FILE *file
)
277 referenced_var_iterator rvi
;
279 fprintf (file
, "\nReferenced variables in %s: %u\n\n",
280 get_name (current_function_decl
), (unsigned) num_referenced_vars
);
282 FOR_EACH_REFERENCED_VAR (var
, rvi
)
284 fprintf (file
, "Variable: ");
285 dump_variable (file
, var
);
286 fprintf (file
, "\n");
291 /* Dump the list of all the referenced variables to stderr. */
294 debug_referenced_vars (void)
296 dump_referenced_vars (stderr
);
300 /* Dump variable VAR and its may-aliases to FILE. */
303 dump_variable (FILE *file
, tree var
)
307 if (TREE_CODE (var
) == SSA_NAME
)
309 if (POINTER_TYPE_P (TREE_TYPE (var
)))
310 dump_points_to_info_for (file
, var
);
311 var
= SSA_NAME_VAR (var
);
314 if (var
== NULL_TREE
)
316 fprintf (file
, "<nil>");
320 print_generic_expr (file
, var
, dump_flags
);
324 fprintf (file
, ", UID D.%u", (unsigned) DECL_UID (var
));
326 fprintf (file
, ", ");
327 print_generic_expr (file
, TREE_TYPE (var
), dump_flags
);
329 if (ann
&& ann
->symbol_mem_tag
)
331 fprintf (file
, ", symbol memory tag: ");
332 print_generic_expr (file
, ann
->symbol_mem_tag
, dump_flags
);
335 if (TREE_ADDRESSABLE (var
))
336 fprintf (file
, ", is addressable");
338 if (is_global_var (var
))
339 fprintf (file
, ", is global");
341 if (TREE_THIS_VOLATILE (var
))
342 fprintf (file
, ", is volatile");
344 dump_mem_sym_stats_for_var (file
, var
);
346 if (is_call_clobbered (var
))
349 var_ann_t va
= var_ann (var
);
350 unsigned int escape_mask
= va
->escape_mask
;
352 fprintf (file
, ", call clobbered");
353 fprintf (file
, " (");
354 if (escape_mask
& ESCAPE_STORED_IN_GLOBAL
)
355 { fprintf (file
, "%sstored in global", s
); s
= ", "; }
356 if (escape_mask
& ESCAPE_TO_ASM
)
357 { fprintf (file
, "%sgoes through ASM", s
); s
= ", "; }
358 if (escape_mask
& ESCAPE_TO_CALL
)
359 { fprintf (file
, "%spassed to call", s
); s
= ", "; }
360 if (escape_mask
& ESCAPE_BAD_CAST
)
361 { fprintf (file
, "%sbad cast", s
); s
= ", "; }
362 if (escape_mask
& ESCAPE_TO_RETURN
)
363 { fprintf (file
, "%sreturned from func", s
); s
= ", "; }
364 if (escape_mask
& ESCAPE_TO_PURE_CONST
)
365 { fprintf (file
, "%spassed to pure/const", s
); s
= ", "; }
366 if (escape_mask
& ESCAPE_IS_GLOBAL
)
367 { fprintf (file
, "%sis global var", s
); s
= ", "; }
368 if (escape_mask
& ESCAPE_IS_PARM
)
369 { fprintf (file
, "%sis incoming pointer", s
); s
= ", "; }
370 if (escape_mask
& ESCAPE_UNKNOWN
)
371 { fprintf (file
, "%sunknown escape", s
); s
= ", "; }
375 if (ann
->noalias_state
== NO_ALIAS
)
376 fprintf (file
, ", NO_ALIAS (does not alias other NO_ALIAS symbols)");
377 else if (ann
->noalias_state
== NO_ALIAS_GLOBAL
)
378 fprintf (file
, ", NO_ALIAS_GLOBAL (does not alias other NO_ALIAS symbols"
379 " and global vars)");
380 else if (ann
->noalias_state
== NO_ALIAS_ANYTHING
)
381 fprintf (file
, ", NO_ALIAS_ANYTHING (does not alias any other symbols)");
383 if (gimple_default_def (cfun
, var
))
385 fprintf (file
, ", default def: ");
386 print_generic_expr (file
, gimple_default_def (cfun
, var
), dump_flags
);
389 if (MTAG_P (var
) && may_aliases (var
))
391 fprintf (file
, ", may aliases: ");
392 dump_may_aliases_for (file
, var
);
395 if (!is_gimple_reg (var
))
397 if (memory_partition (var
))
399 fprintf (file
, ", belongs to partition: ");
400 print_generic_expr (file
, memory_partition (var
), dump_flags
);
403 if (TREE_CODE (var
) == MEMORY_PARTITION_TAG
)
405 fprintf (file
, ", partition symbols: ");
406 dump_decl_set (file
, MPT_SYMBOLS (var
));
410 fprintf (file
, "\n");
414 /* Dump variable VAR and its may-aliases to stderr. */
417 debug_variable (tree var
)
419 dump_variable (stderr
, var
);
423 /* Dump various DFA statistics to FILE. */
426 dump_dfa_stats (FILE *file
)
428 struct dfa_stats_d dfa_stats
;
430 unsigned long size
, total
= 0;
431 const char * const fmt_str
= "%-30s%-13s%12s\n";
432 const char * const fmt_str_1
= "%-30s%13lu%11lu%c\n";
433 const char * const fmt_str_3
= "%-43s%11lu%c\n";
435 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
437 collect_dfa_stats (&dfa_stats
);
439 fprintf (file
, "\nDFA Statistics for %s\n\n", funcname
);
441 fprintf (file
, "---------------------------------------------------------\n");
442 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
443 fprintf (file
, fmt_str
, "", " instances ", "used ");
444 fprintf (file
, "---------------------------------------------------------\n");
446 size
= num_referenced_vars
* sizeof (tree
);
448 fprintf (file
, fmt_str_1
, "Referenced variables", (unsigned long)num_referenced_vars
,
449 SCALE (size
), LABEL (size
));
451 size
= dfa_stats
.num_stmt_anns
* sizeof (struct stmt_ann_d
);
453 fprintf (file
, fmt_str_1
, "Statements annotated", dfa_stats
.num_stmt_anns
,
454 SCALE (size
), LABEL (size
));
456 size
= dfa_stats
.num_var_anns
* sizeof (struct var_ann_d
);
458 fprintf (file
, fmt_str_1
, "Variables annotated", dfa_stats
.num_var_anns
,
459 SCALE (size
), LABEL (size
));
461 size
= dfa_stats
.num_uses
* sizeof (tree
*);
463 fprintf (file
, fmt_str_1
, "USE operands", dfa_stats
.num_uses
,
464 SCALE (size
), LABEL (size
));
466 size
= dfa_stats
.num_defs
* sizeof (tree
*);
468 fprintf (file
, fmt_str_1
, "DEF operands", dfa_stats
.num_defs
,
469 SCALE (size
), LABEL (size
));
471 size
= dfa_stats
.num_vuses
* sizeof (tree
*);
473 fprintf (file
, fmt_str_1
, "VUSE operands", dfa_stats
.num_vuses
,
474 SCALE (size
), LABEL (size
));
476 size
= dfa_stats
.num_vdefs
* sizeof (tree
*);
478 fprintf (file
, fmt_str_1
, "VDEF operands", dfa_stats
.num_vdefs
,
479 SCALE (size
), LABEL (size
));
481 size
= dfa_stats
.num_phis
* sizeof (struct tree_phi_node
);
483 fprintf (file
, fmt_str_1
, "PHI nodes", dfa_stats
.num_phis
,
484 SCALE (size
), LABEL (size
));
486 size
= dfa_stats
.num_phi_args
* sizeof (struct phi_arg_d
);
488 fprintf (file
, fmt_str_1
, "PHI arguments", dfa_stats
.num_phi_args
,
489 SCALE (size
), LABEL (size
));
491 fprintf (file
, "---------------------------------------------------------\n");
492 fprintf (file
, fmt_str_3
, "Total memory used by DFA/SSA data", SCALE (total
),
494 fprintf (file
, "---------------------------------------------------------\n");
495 fprintf (file
, "\n");
497 if (dfa_stats
.num_phis
)
498 fprintf (file
, "Average number of arguments per PHI node: %.1f (max: %d)\n",
499 (float) dfa_stats
.num_phi_args
/ (float) dfa_stats
.num_phis
,
500 dfa_stats
.max_num_phi_args
);
502 fprintf (file
, "\n");
506 /* Dump DFA statistics on stderr. */
509 debug_dfa_stats (void)
511 dump_dfa_stats (stderr
);
515 /* Collect DFA statistics and store them in the structure pointed to by
519 collect_dfa_stats (struct dfa_stats_d
*dfa_stats_p
)
521 struct pointer_set_t
*pset
;
523 block_stmt_iterator i
;
525 gcc_assert (dfa_stats_p
);
527 memset ((void *)dfa_stats_p
, 0, sizeof (struct dfa_stats_d
));
529 /* Walk all the trees in the function counting references. Start at
530 basic block NUM_FIXED_BLOCKS, but don't stop at block boundaries. */
531 pset
= pointer_set_create ();
533 for (i
= bsi_start (BASIC_BLOCK (NUM_FIXED_BLOCKS
));
534 !bsi_end_p (i
); bsi_next (&i
))
535 walk_tree (bsi_stmt_ptr (i
), collect_dfa_stats_r
, (void *) dfa_stats_p
,
538 pointer_set_destroy (pset
);
543 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
545 dfa_stats_p
->num_phis
++;
546 dfa_stats_p
->num_phi_args
+= PHI_NUM_ARGS (phi
);
547 if (PHI_NUM_ARGS (phi
) > dfa_stats_p
->max_num_phi_args
)
548 dfa_stats_p
->max_num_phi_args
= PHI_NUM_ARGS (phi
);
554 /* Callback for walk_tree to collect DFA statistics for a tree and its
558 collect_dfa_stats_r (tree
*tp
, int *walk_subtrees ATTRIBUTE_UNUSED
,
562 struct dfa_stats_d
*dfa_stats_p
= (struct dfa_stats_d
*)data
;
566 switch (ann_type (t
->base
.ann
))
570 dfa_stats_p
->num_stmt_anns
++;
571 dfa_stats_p
->num_defs
+= NUM_SSA_OPERANDS (t
, SSA_OP_DEF
);
572 dfa_stats_p
->num_uses
+= NUM_SSA_OPERANDS (t
, SSA_OP_USE
);
573 dfa_stats_p
->num_vdefs
+= NUM_SSA_OPERANDS (t
, SSA_OP_VDEF
);
574 dfa_stats_p
->num_vuses
+= NUM_SSA_OPERANDS (t
, SSA_OP_VUSE
);
579 dfa_stats_p
->num_var_anns
++;
591 /*---------------------------------------------------------------------------
592 Miscellaneous helpers
593 ---------------------------------------------------------------------------*/
594 /* Callback for walk_tree. Used to collect variables referenced in
598 find_vars_r (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
600 /* If we are reading the lto info back in, we need to rescan the
602 if (TREE_CODE (*tp
) == SSA_NAME
)
603 add_referenced_var (SSA_NAME_VAR (*tp
));
605 /* If T is a regular variable that the optimizers are interested
606 in, add it to the list of variables. */
607 else if (SSA_VAR_P (*tp
))
608 add_referenced_var (*tp
);
610 /* Type, _DECL and constant nodes have no interesting children.
612 else if (IS_TYPE_OR_DECL_P (*tp
) || CONSTANT_CLASS_P (*tp
))
618 /* Lookup UID in the referenced_vars hashtable and return the associated
622 referenced_var_lookup (unsigned int uid
)
625 struct tree_decl_minimal in
;
627 h
= (tree
) htab_find_with_hash (gimple_referenced_vars (cfun
), &in
, uid
);
628 gcc_assert (h
|| uid
== 0);
632 /* Check if TO is in the referenced_vars hash table and insert it if not.
633 Return true if it required insertion. */
636 referenced_var_check_and_insert (tree to
)
639 struct tree_decl_minimal in
;
640 unsigned int uid
= DECL_UID (to
);
643 h
= (tree
) htab_find_with_hash (gimple_referenced_vars (cfun
), &in
, uid
);
646 /* DECL_UID has already been entered in the table. Verify that it is
647 the same entry as TO. See PR 27793. */
648 gcc_assert (h
== to
);
652 loc
= (tree
*) htab_find_slot_with_hash (gimple_referenced_vars (cfun
),
658 /* Lookup VAR UID in the default_defs hashtable and return the associated
662 gimple_default_def (struct function
*fn
, tree var
)
664 struct tree_decl_minimal ind
;
665 struct tree_ssa_name in
;
666 gcc_assert (SSA_VAR_P (var
));
668 ind
.uid
= DECL_UID (var
);
669 return (tree
) htab_find_with_hash (DEFAULT_DEFS (fn
), &in
, DECL_UID (var
));
672 /* Insert the pair VAR's UID, DEF into the default_defs hashtable. */
675 set_default_def (tree var
, tree def
)
677 struct tree_decl_minimal ind
;
678 struct tree_ssa_name in
;
681 gcc_assert (SSA_VAR_P (var
));
683 ind
.uid
= DECL_UID (var
);
686 loc
= htab_find_slot_with_hash (DEFAULT_DEFS (cfun
), &in
,
687 DECL_UID (var
), INSERT
);
689 htab_remove_elt (DEFAULT_DEFS (cfun
), *loc
);
692 gcc_assert (TREE_CODE (def
) == SSA_NAME
&& SSA_NAME_VAR (def
) == var
);
693 loc
= htab_find_slot_with_hash (DEFAULT_DEFS (cfun
), &in
,
694 DECL_UID (var
), INSERT
);
696 /* Default definition might be changed by tail call optimization. */
698 SSA_NAME_IS_DEFAULT_DEF (*(tree
*) loc
) = false;
701 /* Mark DEF as the default definition for VAR. */
702 SSA_NAME_IS_DEFAULT_DEF (def
) = true;
705 /* Add VAR to the list of referenced variables if it isn't already there. */
708 add_referenced_var (tree var
)
712 v_ann
= get_var_ann (var
);
713 gcc_assert (DECL_P (var
));
715 /* Insert VAR into the referenced_vars has table if it isn't present. */
716 if (referenced_var_check_and_insert (var
))
718 /* This is the first time we found this variable, annotate it with
719 attributes that are intrinsic to the variable. */
721 /* Tag's don't have DECL_INITIAL. */
725 /* Scan DECL_INITIAL for pointer variables as they may contain
726 address arithmetic referencing the address of other
728 Even non-constant initializers need to be walked, because
729 IPA passes might prove that their are invariant later on. */
730 if (DECL_INITIAL (var
)
731 /* Initializers of external variables are not useful to the
733 && !DECL_EXTERNAL (var
))
734 walk_tree (&DECL_INITIAL (var
), find_vars_r
, NULL
, 0);
738 /* Remove VAR from the list. */
741 remove_referenced_var (tree var
)
744 struct tree_decl_minimal in
;
746 unsigned int uid
= DECL_UID (var
);
748 clear_call_clobbered (var
);
749 bitmap_clear_bit (gimple_call_used_vars (cfun
), uid
);
750 if ((v_ann
= var_ann (var
)))
752 /* Preserve var_anns of globals, but clear their alias info. */
754 || (!TREE_STATIC (var
) && !DECL_EXTERNAL (var
)))
757 var
->base
.ann
= NULL
;
761 v_ann
->mpt
= NULL_TREE
;
762 v_ann
->symbol_mem_tag
= NULL_TREE
;
765 gcc_assert (DECL_P (var
));
767 loc
= htab_find_slot_with_hash (gimple_referenced_vars (cfun
), &in
, uid
,
769 htab_clear_slot (gimple_referenced_vars (cfun
), loc
);
773 /* Return the virtual variable associated to the non-scalar variable VAR. */
776 get_virtual_var (tree var
)
780 if (TREE_CODE (var
) == SSA_NAME
)
781 var
= SSA_NAME_VAR (var
);
783 while (TREE_CODE (var
) == REALPART_EXPR
|| TREE_CODE (var
) == IMAGPART_EXPR
784 || handled_component_p (var
))
785 var
= TREE_OPERAND (var
, 0);
787 /* Treating GIMPLE registers as virtual variables makes no sense.
788 Also complain if we couldn't extract a _DECL out of the original
790 gcc_assert (SSA_VAR_P (var
));
791 gcc_assert (!is_gimple_reg (var
));
796 /* Mark all the naked symbols in STMT for SSA renaming.
798 NOTE: This function should only be used for brand new statements.
799 If the caller is modifying an existing statement, it should use the
800 combination push_stmt_changes/pop_stmt_changes. */
803 mark_symbols_for_renaming (tree stmt
)
810 /* Mark all the operands for renaming. */
811 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, iter
, SSA_OP_ALL_OPERANDS
)
813 mark_sym_for_renaming (op
);
817 /* Find all variables within the gimplified statement that were not previously
818 visible to the function and add them to the referenced variables list. */
821 find_new_referenced_vars_1 (tree
*tp
, int *walk_subtrees
,
822 void *data ATTRIBUTE_UNUSED
)
826 if (TREE_CODE (t
) == VAR_DECL
&& !var_ann (t
))
828 add_referenced_var (t
);
829 mark_sym_for_renaming (t
);
832 if (IS_TYPE_OR_DECL_P (t
))
839 find_new_referenced_vars (tree
*stmt_p
)
841 walk_tree (stmt_p
, find_new_referenced_vars_1
, NULL
, NULL
);
845 /* If EXP is a handled component reference for a structure, return the
846 base variable. The access range is delimited by bit positions *POFFSET and
847 *POFFSET + *PMAX_SIZE. The access size is *PSIZE bits. If either
848 *PSIZE or *PMAX_SIZE is -1, they could not be determined. If *PSIZE
849 and *PMAX_SIZE are equal, the access is non-variable. */
852 get_ref_base_and_extent (tree exp
, HOST_WIDE_INT
*poffset
,
853 HOST_WIDE_INT
*psize
,
854 HOST_WIDE_INT
*pmax_size
)
856 HOST_WIDE_INT bitsize
= -1;
857 HOST_WIDE_INT maxsize
= -1;
858 tree size_tree
= NULL_TREE
;
859 HOST_WIDE_INT bit_offset
= 0;
860 bool seen_variable_array_ref
= false;
862 gcc_assert (!SSA_VAR_P (exp
));
864 /* First get the final access size from just the outermost expression. */
865 if (TREE_CODE (exp
) == COMPONENT_REF
)
866 size_tree
= DECL_SIZE (TREE_OPERAND (exp
, 1));
867 else if (TREE_CODE (exp
) == BIT_FIELD_REF
)
868 size_tree
= TREE_OPERAND (exp
, 1);
871 enum machine_mode mode
= TYPE_MODE (TREE_TYPE (exp
));
873 size_tree
= TYPE_SIZE (TREE_TYPE (exp
));
875 bitsize
= GET_MODE_BITSIZE (mode
);
877 if (size_tree
!= NULL_TREE
)
879 if (! host_integerp (size_tree
, 1))
882 bitsize
= TREE_INT_CST_LOW (size_tree
);
885 /* Initially, maxsize is the same as the accessed element size.
886 In the following it will only grow (or become -1). */
889 /* Compute cumulative bit-offset for nested component-refs and array-refs,
890 and find the ultimate containing object. */
893 switch (TREE_CODE (exp
))
896 bit_offset
+= tree_low_cst (TREE_OPERAND (exp
, 2), 0);
901 tree field
= TREE_OPERAND (exp
, 1);
902 tree this_offset
= component_ref_field_offset (exp
);
904 if (this_offset
&& TREE_CODE (this_offset
) == INTEGER_CST
)
906 HOST_WIDE_INT hthis_offset
= tree_low_cst (this_offset
, 0);
908 hthis_offset
*= BITS_PER_UNIT
;
909 bit_offset
+= hthis_offset
;
910 bit_offset
+= tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 0);
914 tree csize
= TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp
, 0)));
915 /* We need to adjust maxsize to the whole structure bitsize.
916 But we can subtract any constant offset seen so far,
917 because that would get us out of the structure otherwise. */
918 if (maxsize
!= -1 && csize
&& host_integerp (csize
, 1))
919 maxsize
= TREE_INT_CST_LOW (csize
) - bit_offset
;
927 case ARRAY_RANGE_REF
:
929 tree index
= TREE_OPERAND (exp
, 1);
930 tree low_bound
= array_ref_low_bound (exp
);
931 tree unit_size
= array_ref_element_size (exp
);
933 /* If the resulting bit-offset is constant, track it. */
934 if (host_integerp (index
, 0)
935 && host_integerp (low_bound
, 0)
936 && host_integerp (unit_size
, 1))
938 HOST_WIDE_INT hindex
= tree_low_cst (index
, 0);
940 hindex
-= tree_low_cst (low_bound
, 0);
941 hindex
*= tree_low_cst (unit_size
, 1);
942 hindex
*= BITS_PER_UNIT
;
943 bit_offset
+= hindex
;
945 /* An array ref with a constant index up in the structure
946 hierarchy will constrain the size of any variable array ref
947 lower in the access hierarchy. */
948 seen_variable_array_ref
= false;
952 tree asize
= TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp
, 0)));
953 /* We need to adjust maxsize to the whole array bitsize.
954 But we can subtract any constant offset seen so far,
955 because that would get us outside of the array otherwise. */
956 if (maxsize
!= -1 && asize
&& host_integerp (asize
, 1))
957 maxsize
= TREE_INT_CST_LOW (asize
) - bit_offset
;
961 /* Remember that we have seen an array ref with a variable
963 seen_variable_array_ref
= true;
972 bit_offset
+= bitsize
;
975 case VIEW_CONVERT_EXPR
:
976 /* ??? We probably should give up here and bail out. */
983 exp
= TREE_OPERAND (exp
, 0);
987 /* We need to deal with variable arrays ending structures such as
988 struct { int length; int a[1]; } x; x.a[d]
989 struct { struct { int a; int b; } a[1]; } x; x.a[d].a
990 struct { struct { int a[1]; } a[1]; } x; x.a[0][d], x.a[d][0]
991 where we do not know maxsize for variable index accesses to
992 the array. The simplest way to conservatively deal with this
993 is to punt in the case that offset + maxsize reaches the
994 base type boundary. */
995 if (seen_variable_array_ref
997 && host_integerp (TYPE_SIZE (TREE_TYPE (exp
)), 1)
998 && bit_offset
+ maxsize
999 == (signed)TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (exp
))))
1002 /* ??? Due to negative offsets in ARRAY_REF we can end up with
1003 negative bit_offset here. We might want to store a zero offset
1005 *poffset
= bit_offset
;
1007 *pmax_size
= maxsize
;
1012 /* Returns true if STMT references an SSA_NAME that has
1013 SSA_NAME_OCCURS_IN_ABNORMAL_PHI set, otherwise false. */
1016 stmt_references_abnormal_ssa_name (tree stmt
)
1019 use_operand_p use_p
;
1021 FOR_EACH_SSA_USE_OPERAND (use_p
, stmt
, oi
, SSA_OP_USE
)
1023 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (use_p
)))
1030 /* Return true, if the two memory references REF1 and REF2 may alias. */
1033 refs_may_alias_p (tree ref1
, tree ref2
)
1036 HOST_WIDE_INT offset1
= 0, offset2
= 0;
1037 HOST_WIDE_INT size1
= -1, size2
= -1;
1038 HOST_WIDE_INT max_size1
= -1, max_size2
= -1;
1039 bool strict_aliasing_applies
;
1041 gcc_assert ((SSA_VAR_P (ref1
)
1042 || handled_component_p (ref1
)
1043 || INDIRECT_REF_P (ref1
)
1044 || TREE_CODE (ref1
) == TARGET_MEM_REF
)
1045 && (SSA_VAR_P (ref2
)
1046 || handled_component_p (ref2
)
1047 || INDIRECT_REF_P (ref2
)
1048 || TREE_CODE (ref2
) == TARGET_MEM_REF
));
1050 /* Defer to TBAA if possible. */
1051 if (flag_strict_aliasing
1052 && !alias_sets_conflict_p (get_alias_set (ref1
), get_alias_set (ref2
)))
1055 /* Decompose the references into their base objects and the access. */
1057 if (handled_component_p (ref1
))
1058 base1
= get_ref_base_and_extent (ref1
, &offset1
, &size1
, &max_size1
);
1060 if (handled_component_p (ref2
))
1061 base2
= get_ref_base_and_extent (ref2
, &offset2
, &size2
, &max_size2
);
1063 /* If both references are based on different variables, they cannot alias.
1064 If both references are based on the same variable, they cannot alias if
1065 the accesses do not overlap. */
1066 if (SSA_VAR_P (base1
)
1067 && SSA_VAR_P (base2
))
1069 if (!operand_equal_p (base1
, base2
, 0))
1071 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
1074 /* If one base is a ref-all pointer weird things are allowed. */
1075 strict_aliasing_applies
= (flag_strict_aliasing
1076 && (!INDIRECT_REF_P (base1
)
1077 || get_alias_set (base1
) != 0)
1078 && (!INDIRECT_REF_P (base2
)
1079 || get_alias_set (base2
) != 0));
1081 /* If strict aliasing applies the only way to access a scalar variable
1082 is through a pointer dereference or through a union (gcc extension). */
1083 if (strict_aliasing_applies
1084 && ((SSA_VAR_P (ref2
)
1085 && !AGGREGATE_TYPE_P (TREE_TYPE (ref2
))
1086 && !INDIRECT_REF_P (ref1
)
1087 && TREE_CODE (TREE_TYPE (base1
)) != UNION_TYPE
)
1088 || (SSA_VAR_P (ref1
)
1089 && !AGGREGATE_TYPE_P (TREE_TYPE (ref1
))
1090 && !INDIRECT_REF_P (ref2
)
1091 && TREE_CODE (TREE_TYPE (base2
)) != UNION_TYPE
)))
1094 /* If both references are through the same type, or if strict aliasing
1095 doesn't apply they are through two same pointers, they do not alias
1096 if the accesses do not overlap. */
1097 if ((strict_aliasing_applies
1098 && (TYPE_MAIN_VARIANT (TREE_TYPE (base1
))
1099 == TYPE_MAIN_VARIANT (TREE_TYPE (base2
))))
1100 || (TREE_CODE (base1
) == INDIRECT_REF
1101 && TREE_CODE (base2
) == INDIRECT_REF
1102 && operand_equal_p (TREE_OPERAND (base1
, 0),
1103 TREE_OPERAND (base2
, 0), 0)))
1104 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
1106 /* If both are component references through pointers try to find a
1107 common base and apply offset based disambiguation. This handles
1109 struct A { int i; int j; } *q;
1110 struct B { struct A a; int k; } *p;
1111 disambiguating q->i and p->a.j. */
1112 if (strict_aliasing_applies
1113 && (TREE_CODE (base1
) == INDIRECT_REF
1114 || TREE_CODE (base2
) == INDIRECT_REF
)
1115 && handled_component_p (ref1
)
1116 && handled_component_p (ref2
))
1119 /* Now search for the type of base1 in the access path of ref2. This
1120 would be a common base for doing offset based disambiguation on. */
1122 while (handled_component_p (*refp
)
1123 /* Note that the following is only conservative if there are
1124 never copies of types appearing as sub-structures. */
1125 && (TYPE_MAIN_VARIANT (TREE_TYPE (*refp
))
1126 != TYPE_MAIN_VARIANT (TREE_TYPE (base1
))))
1127 refp
= &TREE_OPERAND (*refp
, 0);
1128 if (TYPE_MAIN_VARIANT (TREE_TYPE (*refp
))
1129 == TYPE_MAIN_VARIANT (TREE_TYPE (base1
)))
1131 HOST_WIDE_INT offadj
, sztmp
, msztmp
;
1132 get_ref_base_and_extent (*refp
, &offadj
, &sztmp
, &msztmp
);
1134 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
1136 /* The other way around. */
1138 while (handled_component_p (*refp
)
1139 && (TYPE_MAIN_VARIANT (TREE_TYPE (*refp
))
1140 != TYPE_MAIN_VARIANT (TREE_TYPE (base2
))))
1141 refp
= &TREE_OPERAND (*refp
, 0);
1142 if (TYPE_MAIN_VARIANT (TREE_TYPE (*refp
))
1143 == TYPE_MAIN_VARIANT (TREE_TYPE (base2
)))
1145 HOST_WIDE_INT offadj
, sztmp
, msztmp
;
1146 get_ref_base_and_extent (*refp
, &offadj
, &sztmp
, &msztmp
);
1148 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
1150 /* If we can be sure to catch all equivalent types in the search
1151 for the common base then we could return false here. In that
1152 case we would be able to disambiguate q->i and p->k. */
1158 /* Given a stmt STMT that references memory, return the single stmt
1159 that is reached by following the VUSE -> VDEF link. Returns
1160 NULL_TREE, if there is no single stmt that defines all VUSEs of
1162 Note that for a stmt with a single virtual operand this may return
1163 a PHI node as well. Note that if all VUSEs are default definitions
1164 this function will return an empty statement. */
1167 get_single_def_stmt (tree stmt
)
1169 tree def_stmt
= NULL_TREE
;
1173 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, iter
, SSA_OP_VIRTUAL_USES
)
1175 tree tmp
= SSA_NAME_DEF_STMT (use
);
1177 /* ??? This is too simplistic for multiple virtual operands
1178 reaching different PHI nodes of the same basic blocks or for
1179 reaching all default definitions. */
1182 && !(IS_EMPTY_STMT (def_stmt
)
1183 && IS_EMPTY_STMT (tmp
)))
1192 /* Given a PHI node of virtual operands, tries to eliminate cyclic
1193 reached definitions if they do not alias REF and returns the
1194 defining statement of the single virtual operand that flows in
1195 from a non-backedge. Returns NULL_TREE if such statement within
1196 the above conditions cannot be found. */
1199 get_single_def_stmt_from_phi (tree ref
, tree phi
)
1201 tree def_arg
= NULL_TREE
;
1204 /* Find the single PHI argument that is not flowing in from a
1205 back edge and verify that the loop-carried definitions do
1206 not alias the reference we look for. */
1207 for (i
= 0; i
< PHI_NUM_ARGS (phi
); ++i
)
1209 tree arg
= PHI_ARG_DEF (phi
, i
);
1212 if (!(PHI_ARG_EDGE (phi
, i
)->flags
& EDGE_DFS_BACK
))
1214 /* Multiple non-back edges? Do not try to handle this. */
1221 /* Follow the definitions back to the original PHI node. Bail
1222 out once a definition is found that may alias REF. */
1223 def_stmt
= SSA_NAME_DEF_STMT (arg
);
1226 if (TREE_CODE (def_stmt
) != GIMPLE_MODIFY_STMT
1227 || refs_may_alias_p (ref
, GIMPLE_STMT_OPERAND (def_stmt
, 0)))
1229 /* ??? This will only work, reaching the PHI node again if
1230 there is a single virtual operand on def_stmt. */
1231 def_stmt
= get_single_def_stmt (def_stmt
);
1235 while (def_stmt
!= phi
);
1238 return SSA_NAME_DEF_STMT (def_arg
);
1241 /* Return the single reference statement defining all virtual uses
1242 on STMT or NULL_TREE, if there are multiple defining statements.
1243 Take into account only definitions that alias REF if following
1244 back-edges when looking through a loop PHI node. */
1247 get_single_def_stmt_with_phi (tree ref
, tree stmt
)
1249 switch (NUM_SSA_OPERANDS (stmt
, SSA_OP_VIRTUAL_USES
))
1256 tree def_stmt
= SSA_NAME_DEF_STMT (SINGLE_SSA_TREE_OPERAND
1257 (stmt
, SSA_OP_VIRTUAL_USES
));
1258 /* We can handle lookups over PHI nodes only for a single
1260 if (TREE_CODE (def_stmt
) == PHI_NODE
)
1261 return get_single_def_stmt_from_phi (ref
, def_stmt
);
1266 return get_single_def_stmt (stmt
);