1 /* Data flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009
3 Free Software Foundation, Inc.
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"
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. */
60 size_t max_num_phi_args
;
66 /* Local functions. */
67 static void collect_dfa_stats (struct dfa_stats_d
*);
68 static tree
find_vars_r (tree
*, int *, void *);
71 /*---------------------------------------------------------------------------
72 Dataflow analysis (DFA) routines
73 ---------------------------------------------------------------------------*/
74 /* Find all the variables referenced in the function. This function
75 builds the global arrays REFERENCED_VARS and CALL_CLOBBERED_VARS.
77 Note that this function does not look for statement operands, it simply
78 determines what variables are referenced in the program and detects
79 various attributes for each variable used by alias analysis and the
83 find_referenced_vars (void)
86 gimple_stmt_iterator si
;
90 for (si
= gsi_start_bb (bb
); !gsi_end_p (si
); gsi_next (&si
))
91 find_referenced_vars_in (gsi_stmt (si
));
93 for (si
= gsi_start_phis (bb
); !gsi_end_p (si
); gsi_next (&si
))
94 find_referenced_vars_in (gsi_stmt (si
));
100 struct gimple_opt_pass pass_referenced_vars
=
106 find_referenced_vars
, /* execute */
109 0, /* static_pass_number */
110 TV_FIND_REFERENCED_VARS
, /* tv_id */
111 PROP_gimple_leh
| PROP_cfg
, /* properties_required */
112 PROP_referenced_vars
, /* properties_provided */
113 0, /* properties_destroyed */
114 TODO_dump_func
, /* todo_flags_start */
115 TODO_dump_func
/* todo_flags_finish */
120 /*---------------------------------------------------------------------------
122 ---------------------------------------------------------------------------*/
123 /* Create a new annotation for a _DECL node T. */
126 create_var_ann (tree t
)
131 gcc_assert (DECL_P (t
));
132 gcc_assert (!t
->base
.ann
|| t
->base
.ann
->common
.type
== VAR_ANN
);
134 ann
= GGC_CNEW (struct var_ann_d
);
135 ann
->common
.type
= VAR_ANN
;
136 t
->base
.ann
= (tree_ann_t
) ann
;
141 /* Renumber all of the gimple stmt uids. */
144 renumber_gimple_stmt_uids (void)
148 set_gimple_stmt_max_uid (cfun
, 0);
151 gimple_stmt_iterator bsi
;
152 for (bsi
= gsi_start_bb (bb
); !gsi_end_p (bsi
); gsi_next (&bsi
))
154 gimple stmt
= gsi_stmt (bsi
);
155 gimple_set_uid (stmt
, inc_gimple_stmt_max_uid (cfun
));
160 /* Create a new annotation for a tree T. */
163 create_tree_common_ann (tree t
)
165 tree_ann_common_t ann
;
168 gcc_assert (!t
->base
.ann
|| t
->base
.ann
->common
.type
== TREE_ANN_COMMON
);
170 ann
= GGC_CNEW (struct tree_ann_common_d
);
172 ann
->type
= TREE_ANN_COMMON
;
174 t
->base
.ann
= (tree_ann_t
) ann
;
179 /* Build a temporary. Make sure and register it to be renamed. */
182 make_rename_temp (tree type
, const char *prefix
)
184 tree t
= create_tmp_var (type
, prefix
);
186 if (TREE_CODE (TREE_TYPE (t
)) == COMPLEX_TYPE
187 || TREE_CODE (TREE_TYPE (t
)) == VECTOR_TYPE
)
188 DECL_GIMPLE_REG_P (t
) = 1;
190 if (gimple_referenced_vars (cfun
))
192 add_referenced_var (t
);
193 mark_sym_for_renaming (t
);
201 /*---------------------------------------------------------------------------
203 ---------------------------------------------------------------------------*/
204 /* Dump the list of all the referenced variables in the current function to
208 dump_referenced_vars (FILE *file
)
211 referenced_var_iterator rvi
;
213 fprintf (file
, "\nReferenced variables in %s: %u\n\n",
214 get_name (current_function_decl
), (unsigned) num_referenced_vars
);
216 FOR_EACH_REFERENCED_VAR (var
, rvi
)
218 fprintf (file
, "Variable: ");
219 dump_variable (file
, var
);
222 fprintf (file
, "\n");
226 /* Dump the list of all the referenced variables to stderr. */
229 debug_referenced_vars (void)
231 dump_referenced_vars (stderr
);
235 /* Dump variable VAR and its may-aliases to FILE. */
238 dump_variable (FILE *file
, tree var
)
242 if (TREE_CODE (var
) == SSA_NAME
)
244 if (POINTER_TYPE_P (TREE_TYPE (var
)))
245 dump_points_to_info_for (file
, var
);
246 var
= SSA_NAME_VAR (var
);
249 if (var
== NULL_TREE
)
251 fprintf (file
, "<nil>");
255 print_generic_expr (file
, var
, dump_flags
);
259 fprintf (file
, ", UID D.%u", (unsigned) DECL_UID (var
));
261 fprintf (file
, ", ");
262 print_generic_expr (file
, TREE_TYPE (var
), dump_flags
);
264 if (TREE_ADDRESSABLE (var
))
265 fprintf (file
, ", is addressable");
267 if (is_global_var (var
))
268 fprintf (file
, ", is global");
270 if (TREE_THIS_VOLATILE (var
))
271 fprintf (file
, ", is volatile");
273 if (is_call_clobbered (var
))
274 fprintf (file
, ", call clobbered");
275 else if (is_call_used (var
))
276 fprintf (file
, ", call used");
278 if (ann
->noalias_state
== NO_ALIAS
)
279 fprintf (file
, ", NO_ALIAS (does not alias other NO_ALIAS symbols)");
280 else if (ann
->noalias_state
== NO_ALIAS_GLOBAL
)
281 fprintf (file
, ", NO_ALIAS_GLOBAL (does not alias other NO_ALIAS symbols"
282 " and global vars)");
283 else if (ann
->noalias_state
== NO_ALIAS_ANYTHING
)
284 fprintf (file
, ", NO_ALIAS_ANYTHING (does not alias any other symbols)");
286 if (gimple_default_def (cfun
, var
))
288 fprintf (file
, ", default def: ");
289 print_generic_expr (file
, gimple_default_def (cfun
, var
), dump_flags
);
292 fprintf (file
, "\n");
296 /* Dump variable VAR and its may-aliases to stderr. */
299 debug_variable (tree var
)
301 dump_variable (stderr
, var
);
305 /* Dump various DFA statistics to FILE. */
308 dump_dfa_stats (FILE *file
)
310 struct dfa_stats_d dfa_stats
;
312 unsigned long size
, total
= 0;
313 const char * const fmt_str
= "%-30s%-13s%12s\n";
314 const char * const fmt_str_1
= "%-30s%13lu%11lu%c\n";
315 const char * const fmt_str_3
= "%-43s%11lu%c\n";
317 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
319 collect_dfa_stats (&dfa_stats
);
321 fprintf (file
, "\nDFA Statistics for %s\n\n", funcname
);
323 fprintf (file
, "---------------------------------------------------------\n");
324 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
325 fprintf (file
, fmt_str
, "", " instances ", "used ");
326 fprintf (file
, "---------------------------------------------------------\n");
328 size
= num_referenced_vars
* sizeof (tree
);
330 fprintf (file
, fmt_str_1
, "Referenced variables", (unsigned long)num_referenced_vars
,
331 SCALE (size
), LABEL (size
));
333 size
= dfa_stats
.num_var_anns
* sizeof (struct var_ann_d
);
335 fprintf (file
, fmt_str_1
, "Variables annotated", dfa_stats
.num_var_anns
,
336 SCALE (size
), LABEL (size
));
338 size
= dfa_stats
.num_uses
* sizeof (tree
*);
340 fprintf (file
, fmt_str_1
, "USE operands", dfa_stats
.num_uses
,
341 SCALE (size
), LABEL (size
));
343 size
= dfa_stats
.num_defs
* sizeof (tree
*);
345 fprintf (file
, fmt_str_1
, "DEF operands", dfa_stats
.num_defs
,
346 SCALE (size
), LABEL (size
));
348 size
= dfa_stats
.num_vuses
* sizeof (tree
*);
350 fprintf (file
, fmt_str_1
, "VUSE operands", dfa_stats
.num_vuses
,
351 SCALE (size
), LABEL (size
));
353 size
= dfa_stats
.num_vdefs
* sizeof (tree
*);
355 fprintf (file
, fmt_str_1
, "VDEF operands", dfa_stats
.num_vdefs
,
356 SCALE (size
), LABEL (size
));
358 size
= dfa_stats
.num_phis
* sizeof (struct gimple_statement_phi
);
360 fprintf (file
, fmt_str_1
, "PHI nodes", dfa_stats
.num_phis
,
361 SCALE (size
), LABEL (size
));
363 size
= dfa_stats
.num_phi_args
* sizeof (struct phi_arg_d
);
365 fprintf (file
, fmt_str_1
, "PHI arguments", dfa_stats
.num_phi_args
,
366 SCALE (size
), LABEL (size
));
368 fprintf (file
, "---------------------------------------------------------\n");
369 fprintf (file
, fmt_str_3
, "Total memory used by DFA/SSA data", SCALE (total
),
371 fprintf (file
, "---------------------------------------------------------\n");
372 fprintf (file
, "\n");
374 if (dfa_stats
.num_phis
)
375 fprintf (file
, "Average number of arguments per PHI node: %.1f (max: %ld)\n",
376 (float) dfa_stats
.num_phi_args
/ (float) dfa_stats
.num_phis
,
377 (long) dfa_stats
.max_num_phi_args
);
379 fprintf (file
, "\n");
383 /* Dump DFA statistics on stderr. */
386 debug_dfa_stats (void)
388 dump_dfa_stats (stderr
);
392 /* Collect DFA statistics and store them in the structure pointed to by
396 collect_dfa_stats (struct dfa_stats_d
*dfa_stats_p ATTRIBUTE_UNUSED
)
399 referenced_var_iterator vi
;
402 gcc_assert (dfa_stats_p
);
404 memset ((void *)dfa_stats_p
, 0, sizeof (struct dfa_stats_d
));
406 /* Count all the variable annotations. */
407 FOR_EACH_REFERENCED_VAR (var
, vi
)
409 dfa_stats_p
->num_var_anns
++;
411 /* Walk all the statements in the function counting references. */
414 gimple_stmt_iterator si
;
416 for (si
= gsi_start_phis (bb
); !gsi_end_p (si
); gsi_next (&si
))
418 gimple phi
= gsi_stmt (si
);
419 dfa_stats_p
->num_phis
++;
420 dfa_stats_p
->num_phi_args
+= gimple_phi_num_args (phi
);
421 if (gimple_phi_num_args (phi
) > dfa_stats_p
->max_num_phi_args
)
422 dfa_stats_p
->max_num_phi_args
= gimple_phi_num_args (phi
);
425 for (si
= gsi_start_bb (bb
); !gsi_end_p (si
); gsi_next (&si
))
427 gimple stmt
= gsi_stmt (si
);
428 dfa_stats_p
->num_defs
+= NUM_SSA_OPERANDS (stmt
, SSA_OP_DEF
);
429 dfa_stats_p
->num_uses
+= NUM_SSA_OPERANDS (stmt
, SSA_OP_USE
);
430 dfa_stats_p
->num_vdefs
+= gimple_vdef (stmt
) ? 1 : 0;
431 dfa_stats_p
->num_vuses
+= gimple_vuse (stmt
) ? 1 : 0;
437 /*---------------------------------------------------------------------------
438 Miscellaneous helpers
439 ---------------------------------------------------------------------------*/
440 /* Callback for walk_tree. Used to collect variables referenced in
444 find_vars_r (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
446 /* If we are reading the lto info back in, we need to rescan the
448 if (TREE_CODE (*tp
) == SSA_NAME
)
449 add_referenced_var (SSA_NAME_VAR (*tp
));
451 /* If T is a regular variable that the optimizers are interested
452 in, add it to the list of variables. */
453 else if (SSA_VAR_P (*tp
))
454 add_referenced_var (*tp
);
456 /* Type, _DECL and constant nodes have no interesting children.
458 else if (IS_TYPE_OR_DECL_P (*tp
) || CONSTANT_CLASS_P (*tp
))
464 /* Find referenced variables in STMT. In contrast with
465 find_new_referenced_vars, this function will not mark newly found
466 variables for renaming. */
469 find_referenced_vars_in (gimple stmt
)
473 if (gimple_code (stmt
) != GIMPLE_PHI
)
475 for (i
= 0; i
< gimple_num_ops (stmt
); i
++)
476 walk_tree (gimple_op_ptr (stmt
, i
), find_vars_r
, NULL
, NULL
);
480 walk_tree (gimple_phi_result_ptr (stmt
), find_vars_r
, NULL
, NULL
);
482 for (i
= 0; i
< gimple_phi_num_args (stmt
); i
++)
484 tree arg
= gimple_phi_arg_def (stmt
, i
);
485 walk_tree (&arg
, find_vars_r
, NULL
, NULL
);
491 /* Lookup UID in the referenced_vars hashtable and return the associated
495 referenced_var_lookup (unsigned int uid
)
498 struct tree_decl_minimal in
;
500 h
= (tree
) htab_find_with_hash (gimple_referenced_vars (cfun
), &in
, uid
);
501 gcc_assert (h
|| uid
== 0);
505 /* Check if TO is in the referenced_vars hash table and insert it if not.
506 Return true if it required insertion. */
509 referenced_var_check_and_insert (tree to
)
512 struct tree_decl_minimal in
;
513 unsigned int uid
= DECL_UID (to
);
516 h
= (tree
) htab_find_with_hash (gimple_referenced_vars (cfun
), &in
, uid
);
519 /* DECL_UID has already been entered in the table. Verify that it is
520 the same entry as TO. See PR 27793. */
521 gcc_assert (h
== to
);
525 loc
= (tree
*) htab_find_slot_with_hash (gimple_referenced_vars (cfun
),
531 /* Lookup VAR UID in the default_defs hashtable and return the associated
535 gimple_default_def (struct function
*fn
, tree var
)
537 struct tree_decl_minimal ind
;
538 struct tree_ssa_name in
;
539 gcc_assert (SSA_VAR_P (var
));
541 ind
.uid
= DECL_UID (var
);
542 return (tree
) htab_find_with_hash (DEFAULT_DEFS (fn
), &in
, DECL_UID (var
));
545 /* Insert the pair VAR's UID, DEF into the default_defs hashtable. */
548 set_default_def (tree var
, tree def
)
550 struct tree_decl_minimal ind
;
551 struct tree_ssa_name in
;
554 gcc_assert (SSA_VAR_P (var
));
556 ind
.uid
= DECL_UID (var
);
559 loc
= htab_find_slot_with_hash (DEFAULT_DEFS (cfun
), &in
,
560 DECL_UID (var
), INSERT
);
562 htab_remove_elt (DEFAULT_DEFS (cfun
), *loc
);
565 gcc_assert (TREE_CODE (def
) == SSA_NAME
&& SSA_NAME_VAR (def
) == var
);
566 loc
= htab_find_slot_with_hash (DEFAULT_DEFS (cfun
), &in
,
567 DECL_UID (var
), INSERT
);
569 /* Default definition might be changed by tail call optimization. */
571 SSA_NAME_IS_DEFAULT_DEF (*(tree
*) loc
) = false;
574 /* Mark DEF as the default definition for VAR. */
575 SSA_NAME_IS_DEFAULT_DEF (def
) = true;
578 /* Add VAR to the list of referenced variables if it isn't already there. */
581 add_referenced_var (tree var
)
585 v_ann
= get_var_ann (var
);
586 gcc_assert (DECL_P (var
));
588 /* Insert VAR into the referenced_vars has table if it isn't present. */
589 if (referenced_var_check_and_insert (var
))
591 /* Scan DECL_INITIAL for pointer variables as they may contain
592 address arithmetic referencing the address of other
593 variables. As we are only interested in directly referenced
594 globals or referenced locals restrict this to initializers
595 than can refer to local variables. */
596 if (DECL_INITIAL (var
)
597 && DECL_CONTEXT (var
) == current_function_decl
)
598 walk_tree (&DECL_INITIAL (var
), find_vars_r
, NULL
, 0);
606 /* Remove VAR from the list. */
609 remove_referenced_var (tree var
)
612 struct tree_decl_minimal in
;
614 unsigned int uid
= DECL_UID (var
);
616 /* Preserve var_anns of globals. */
617 if (!is_global_var (var
)
618 && (v_ann
= var_ann (var
)))
621 var
->base
.ann
= NULL
;
623 gcc_assert (DECL_P (var
));
625 loc
= htab_find_slot_with_hash (gimple_referenced_vars (cfun
), &in
, uid
,
627 htab_clear_slot (gimple_referenced_vars (cfun
), loc
);
631 /* Return the virtual variable associated to the non-scalar variable VAR. */
634 get_virtual_var (tree var
)
638 if (TREE_CODE (var
) == SSA_NAME
)
639 var
= SSA_NAME_VAR (var
);
641 while (TREE_CODE (var
) == REALPART_EXPR
|| TREE_CODE (var
) == IMAGPART_EXPR
642 || handled_component_p (var
))
643 var
= TREE_OPERAND (var
, 0);
645 /* Treating GIMPLE registers as virtual variables makes no sense.
646 Also complain if we couldn't extract a _DECL out of the original
648 gcc_assert (SSA_VAR_P (var
));
649 gcc_assert (!is_gimple_reg (var
));
654 /* Mark all the naked symbols in STMT for SSA renaming.
656 NOTE: This function should only be used for brand new statements.
657 If the caller is modifying an existing statement, it should use the
658 combination push_stmt_changes/pop_stmt_changes. */
661 mark_symbols_for_renaming (gimple stmt
)
668 /* Mark all the operands for renaming. */
669 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, iter
, SSA_OP_ALL_OPERANDS
)
671 mark_sym_for_renaming (op
);
675 /* Find all variables within the gimplified statement that were not
676 previously visible to the function and add them to the referenced
680 find_new_referenced_vars_1 (tree
*tp
, int *walk_subtrees
,
681 void *data ATTRIBUTE_UNUSED
)
685 if (TREE_CODE (t
) == VAR_DECL
&& !var_ann (t
))
687 add_referenced_var (t
);
688 mark_sym_for_renaming (t
);
691 if (IS_TYPE_OR_DECL_P (t
))
698 /* Find any new referenced variables in STMT. */
701 find_new_referenced_vars (gimple stmt
)
703 walk_gimple_op (stmt
, find_new_referenced_vars_1
, NULL
);
707 /* If EXP is a handled component reference for a structure, return the
708 base variable. The access range is delimited by bit positions *POFFSET and
709 *POFFSET + *PMAX_SIZE. The access size is *PSIZE bits. If either
710 *PSIZE or *PMAX_SIZE is -1, they could not be determined. If *PSIZE
711 and *PMAX_SIZE are equal, the access is non-variable. */
714 get_ref_base_and_extent (tree exp
, HOST_WIDE_INT
*poffset
,
715 HOST_WIDE_INT
*psize
,
716 HOST_WIDE_INT
*pmax_size
)
718 HOST_WIDE_INT bitsize
= -1;
719 HOST_WIDE_INT maxsize
= -1;
720 tree size_tree
= NULL_TREE
;
721 HOST_WIDE_INT bit_offset
= 0;
722 bool seen_variable_array_ref
= false;
723 bool seen_union
= false;
725 /* First get the final access size from just the outermost expression. */
726 if (TREE_CODE (exp
) == COMPONENT_REF
)
727 size_tree
= DECL_SIZE (TREE_OPERAND (exp
, 1));
728 else if (TREE_CODE (exp
) == BIT_FIELD_REF
)
729 size_tree
= TREE_OPERAND (exp
, 1);
732 enum machine_mode mode
= TYPE_MODE (TREE_TYPE (exp
));
734 size_tree
= TYPE_SIZE (TREE_TYPE (exp
));
736 bitsize
= GET_MODE_BITSIZE (mode
);
738 if (size_tree
!= NULL_TREE
)
740 if (! host_integerp (size_tree
, 1))
743 bitsize
= TREE_INT_CST_LOW (size_tree
);
746 /* Initially, maxsize is the same as the accessed element size.
747 In the following it will only grow (or become -1). */
750 /* Compute cumulative bit-offset for nested component-refs and array-refs,
751 and find the ultimate containing object. */
754 switch (TREE_CODE (exp
))
757 bit_offset
+= tree_low_cst (TREE_OPERAND (exp
, 2), 0);
762 tree field
= TREE_OPERAND (exp
, 1);
763 tree this_offset
= component_ref_field_offset (exp
);
765 if (TREE_CODE (TREE_TYPE (TREE_OPERAND (exp
, 0))) == UNION_TYPE
)
768 if (this_offset
&& TREE_CODE (this_offset
) == INTEGER_CST
)
770 HOST_WIDE_INT hthis_offset
= tree_low_cst (this_offset
, 0);
772 hthis_offset
*= BITS_PER_UNIT
;
773 bit_offset
+= hthis_offset
;
774 bit_offset
+= tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 0);
778 tree csize
= TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp
, 0)));
779 /* We need to adjust maxsize to the whole structure bitsize.
780 But we can subtract any constant offset seen so far,
781 because that would get us out of the structure otherwise. */
782 if (maxsize
!= -1 && csize
&& host_integerp (csize
, 1))
783 maxsize
= TREE_INT_CST_LOW (csize
) - bit_offset
;
791 case ARRAY_RANGE_REF
:
793 tree index
= TREE_OPERAND (exp
, 1);
794 tree low_bound
= array_ref_low_bound (exp
);
795 tree unit_size
= array_ref_element_size (exp
);
797 /* If the resulting bit-offset is constant, track it. */
798 if (host_integerp (index
, 0)
799 && host_integerp (low_bound
, 0)
800 && host_integerp (unit_size
, 1))
802 HOST_WIDE_INT hindex
= tree_low_cst (index
, 0);
804 hindex
-= tree_low_cst (low_bound
, 0);
805 hindex
*= tree_low_cst (unit_size
, 1);
806 hindex
*= BITS_PER_UNIT
;
807 bit_offset
+= hindex
;
809 /* An array ref with a constant index up in the structure
810 hierarchy will constrain the size of any variable array ref
811 lower in the access hierarchy. */
812 seen_variable_array_ref
= false;
816 tree asize
= TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp
, 0)));
817 /* We need to adjust maxsize to the whole array bitsize.
818 But we can subtract any constant offset seen so far,
819 because that would get us outside of the array otherwise. */
820 if (maxsize
!= -1 && asize
&& host_integerp (asize
, 1))
821 maxsize
= TREE_INT_CST_LOW (asize
) - bit_offset
;
825 /* Remember that we have seen an array ref with a variable
827 seen_variable_array_ref
= true;
836 bit_offset
+= bitsize
;
839 case VIEW_CONVERT_EXPR
:
840 /* ??? We probably should give up here and bail out. */
847 exp
= TREE_OPERAND (exp
, 0);
851 /* We need to deal with variable arrays ending structures such as
852 struct { int length; int a[1]; } x; x.a[d]
853 struct { struct { int a; int b; } a[1]; } x; x.a[d].a
854 struct { struct { int a[1]; } a[1]; } x; x.a[0][d], x.a[d][0]
855 where we do not know maxsize for variable index accesses to
856 the array. The simplest way to conservatively deal with this
857 is to punt in the case that offset + maxsize reaches the
860 Unfortunately this is difficult to determine reliably when unions are
861 involved and so we are conservative in such cases.
863 FIXME: This approach may be too conservative, we probably want to at least
864 check that the union is the last field/element at its level or even
865 propagate the calculated offsets back up the access chain and check
868 if (seen_variable_array_ref
871 && host_integerp (TYPE_SIZE (TREE_TYPE (exp
)), 1)
872 && bit_offset
+ maxsize
873 == (signed) TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (exp
))))))
876 /* ??? Due to negative offsets in ARRAY_REF we can end up with
877 negative bit_offset here. We might want to store a zero offset
879 *poffset
= bit_offset
;
881 *pmax_size
= maxsize
;
886 /* Returns true if STMT references an SSA_NAME that has
887 SSA_NAME_OCCURS_IN_ABNORMAL_PHI set, otherwise false. */
890 stmt_references_abnormal_ssa_name (gimple stmt
)
895 FOR_EACH_SSA_USE_OPERAND (use_p
, stmt
, oi
, SSA_OP_USE
)
897 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (use_p
)))