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))
92 gimple stmt = gsi_stmt (si);
93 if (is_gimple_debug (stmt))
95 find_referenced_vars_in (gsi_stmt (si));
98 for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
99 find_referenced_vars_in (gsi_stmt (si));
105 struct gimple_opt_pass pass_referenced_vars =
109 "*referenced_vars", /* name */
111 find_referenced_vars, /* execute */
114 0, /* static_pass_number */
115 TV_FIND_REFERENCED_VARS, /* tv_id */
116 PROP_gimple_leh | PROP_cfg, /* properties_required */
117 PROP_referenced_vars, /* properties_provided */
118 0, /* properties_destroyed */
119 TODO_dump_func, /* todo_flags_start */
120 TODO_dump_func /* todo_flags_finish */
125 /*---------------------------------------------------------------------------
127 ---------------------------------------------------------------------------*/
128 /* Create a new annotation for a _DECL node T. */
131 create_var_ann (tree t)
136 gcc_assert (TREE_CODE (t) == VAR_DECL
137 || TREE_CODE (t) == PARM_DECL
138 || TREE_CODE (t) == RESULT_DECL);
140 ann = GGC_CNEW (struct var_ann_d);
141 *DECL_VAR_ANN_PTR (t) = ann;
146 /* Renumber all of the gimple stmt uids. */
149 renumber_gimple_stmt_uids (void)
153 set_gimple_stmt_max_uid (cfun, 0);
156 gimple_stmt_iterator bsi;
157 for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
159 gimple stmt = gsi_stmt (bsi);
160 gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
165 /* Like renumber_gimple_stmt_uids, but only do work on the basic blocks
166 in BLOCKS, of which there are N_BLOCKS. Also renumbers PHIs. */
169 renumber_gimple_stmt_uids_in_blocks (basic_block *blocks, int n_blocks)
173 set_gimple_stmt_max_uid (cfun, 0);
174 for (i = 0; i < n_blocks; i++)
176 basic_block bb = blocks[i];
177 gimple_stmt_iterator bsi;
178 for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi))
180 gimple stmt = gsi_stmt (bsi);
181 gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
183 for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
185 gimple stmt = gsi_stmt (bsi);
186 gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
191 /* Build a temporary. Make sure and register it to be renamed. */
194 make_rename_temp (tree type, const char *prefix)
196 tree t = create_tmp_reg (type, prefix);
198 if (gimple_referenced_vars (cfun))
200 add_referenced_var (t);
201 mark_sym_for_renaming (t);
209 /*---------------------------------------------------------------------------
211 ---------------------------------------------------------------------------*/
212 /* Dump the list of all the referenced variables in the current function to
216 dump_referenced_vars (FILE *file)
219 referenced_var_iterator rvi;
221 fprintf (file, "\nReferenced variables in %s: %u\n\n",
222 get_name (current_function_decl), (unsigned) num_referenced_vars);
224 FOR_EACH_REFERENCED_VAR (var, rvi)
226 fprintf (file, "Variable: ");
227 dump_variable (file, var);
230 fprintf (file, "\n");
234 /* Dump the list of all the referenced variables to stderr. */
237 debug_referenced_vars (void)
239 dump_referenced_vars (stderr);
243 /* Dump variable VAR and its may-aliases to FILE. */
246 dump_variable (FILE *file, tree var)
250 if (TREE_CODE (var) == SSA_NAME)
252 if (POINTER_TYPE_P (TREE_TYPE (var)))
253 dump_points_to_info_for (file, var);
254 var = SSA_NAME_VAR (var);
257 if (var == NULL_TREE)
259 fprintf (file, "<nil>");
263 print_generic_expr (file, var, dump_flags);
267 fprintf (file, ", UID D.%u", (unsigned) DECL_UID (var));
268 if (DECL_PT_UID (var) != DECL_UID (var))
269 fprintf (file, ", PT-UID D.%u", (unsigned) DECL_PT_UID (var));
271 fprintf (file, ", ");
272 print_generic_expr (file, TREE_TYPE (var), dump_flags);
274 if (TREE_ADDRESSABLE (var))
275 fprintf (file, ", is addressable");
277 if (is_global_var (var))
278 fprintf (file, ", is global");
280 if (TREE_THIS_VOLATILE (var))
281 fprintf (file, ", is volatile");
283 if (is_call_clobbered (var))
284 fprintf (file, ", call clobbered");
286 if (ann && ann->noalias_state == NO_ALIAS)
287 fprintf (file, ", NO_ALIAS (does not alias other NO_ALIAS symbols)");
288 else if (ann && ann->noalias_state == NO_ALIAS_GLOBAL)
289 fprintf (file, ", NO_ALIAS_GLOBAL (does not alias other NO_ALIAS symbols"
290 " and global vars)");
291 else if (ann && ann->noalias_state == NO_ALIAS_ANYTHING)
292 fprintf (file, ", NO_ALIAS_ANYTHING (does not alias any other symbols)");
294 if (cfun && gimple_default_def (cfun, var))
296 fprintf (file, ", default def: ");
297 print_generic_expr (file, gimple_default_def (cfun, var), dump_flags);
300 if (DECL_INITIAL (var))
302 fprintf (file, ", initial: ");
303 print_generic_expr (file, DECL_INITIAL (var), dump_flags);
306 fprintf (file, "\n");
310 /* Dump variable VAR and its may-aliases to stderr. */
313 debug_variable (tree var)
315 dump_variable (stderr, var);
319 /* Dump various DFA statistics to FILE. */
322 dump_dfa_stats (FILE *file)
324 struct dfa_stats_d dfa_stats;
326 unsigned long size, total = 0;
327 const char * const fmt_str = "%-30s%-13s%12s\n";
328 const char * const fmt_str_1 = "%-30s%13lu%11lu%c\n";
329 const char * const fmt_str_3 = "%-43s%11lu%c\n";
331 = lang_hooks.decl_printable_name (current_function_decl, 2);
333 collect_dfa_stats (&dfa_stats);
335 fprintf (file, "\nDFA Statistics for %s\n\n", funcname);
337 fprintf (file, "---------------------------------------------------------\n");
338 fprintf (file, fmt_str, "", " Number of ", "Memory");
339 fprintf (file, fmt_str, "", " instances ", "used ");
340 fprintf (file, "---------------------------------------------------------\n");
342 size = num_referenced_vars * sizeof (tree);
344 fprintf (file, fmt_str_1, "Referenced variables", (unsigned long)num_referenced_vars,
345 SCALE (size), LABEL (size));
347 size = dfa_stats.num_var_anns * sizeof (struct var_ann_d);
349 fprintf (file, fmt_str_1, "Variables annotated", dfa_stats.num_var_anns,
350 SCALE (size), LABEL (size));
352 size = dfa_stats.num_uses * sizeof (tree *);
354 fprintf (file, fmt_str_1, "USE operands", dfa_stats.num_uses,
355 SCALE (size), LABEL (size));
357 size = dfa_stats.num_defs * sizeof (tree *);
359 fprintf (file, fmt_str_1, "DEF operands", dfa_stats.num_defs,
360 SCALE (size), LABEL (size));
362 size = dfa_stats.num_vuses * sizeof (tree *);
364 fprintf (file, fmt_str_1, "VUSE operands", dfa_stats.num_vuses,
365 SCALE (size), LABEL (size));
367 size = dfa_stats.num_vdefs * sizeof (tree *);
369 fprintf (file, fmt_str_1, "VDEF operands", dfa_stats.num_vdefs,
370 SCALE (size), LABEL (size));
372 size = dfa_stats.num_phis * sizeof (struct gimple_statement_phi);
374 fprintf (file, fmt_str_1, "PHI nodes", dfa_stats.num_phis,
375 SCALE (size), LABEL (size));
377 size = dfa_stats.num_phi_args * sizeof (struct phi_arg_d);
379 fprintf (file, fmt_str_1, "PHI arguments", dfa_stats.num_phi_args,
380 SCALE (size), LABEL (size));
382 fprintf (file, "---------------------------------------------------------\n");
383 fprintf (file, fmt_str_3, "Total memory used by DFA/SSA data", SCALE (total),
385 fprintf (file, "---------------------------------------------------------\n");
386 fprintf (file, "\n");
388 if (dfa_stats.num_phis)
389 fprintf (file, "Average number of arguments per PHI node: %.1f (max: %ld)\n",
390 (float) dfa_stats.num_phi_args / (float) dfa_stats.num_phis,
391 (long) dfa_stats.max_num_phi_args);
393 fprintf (file, "\n");
397 /* Dump DFA statistics on stderr. */
400 debug_dfa_stats (void)
402 dump_dfa_stats (stderr);
406 /* Collect DFA statistics and store them in the structure pointed to by
410 collect_dfa_stats (struct dfa_stats_d *dfa_stats_p ATTRIBUTE_UNUSED)
413 referenced_var_iterator vi;
416 gcc_assert (dfa_stats_p);
418 memset ((void *)dfa_stats_p, 0, sizeof (struct dfa_stats_d));
420 /* Count all the variable annotations. */
421 FOR_EACH_REFERENCED_VAR (var, vi)
423 dfa_stats_p->num_var_anns++;
425 /* Walk all the statements in the function counting references. */
428 gimple_stmt_iterator si;
430 for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
432 gimple phi = gsi_stmt (si);
433 dfa_stats_p->num_phis++;
434 dfa_stats_p->num_phi_args += gimple_phi_num_args (phi);
435 if (gimple_phi_num_args (phi) > dfa_stats_p->max_num_phi_args)
436 dfa_stats_p->max_num_phi_args = gimple_phi_num_args (phi);
439 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
441 gimple stmt = gsi_stmt (si);
442 dfa_stats_p->num_defs += NUM_SSA_OPERANDS (stmt, SSA_OP_DEF);
443 dfa_stats_p->num_uses += NUM_SSA_OPERANDS (stmt, SSA_OP_USE);
444 dfa_stats_p->num_vdefs += gimple_vdef (stmt) ? 1 : 0;
445 dfa_stats_p->num_vuses += gimple_vuse (stmt) ? 1 : 0;
451 /*---------------------------------------------------------------------------
452 Miscellaneous helpers
453 ---------------------------------------------------------------------------*/
454 /* Callback for walk_tree. Used to collect variables referenced in
458 find_vars_r (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
460 /* If we are reading the lto info back in, we need to rescan the
462 if (TREE_CODE (*tp) == SSA_NAME)
463 add_referenced_var (SSA_NAME_VAR (*tp));
465 /* If T is a regular variable that the optimizers are interested
466 in, add it to the list of variables. */
467 else if (SSA_VAR_P (*tp))
468 add_referenced_var (*tp);
470 /* Type, _DECL and constant nodes have no interesting children.
472 else if (IS_TYPE_OR_DECL_P (*tp) || CONSTANT_CLASS_P (*tp))
478 /* Find referenced variables in STMT. In contrast with
479 find_new_referenced_vars, this function will not mark newly found
480 variables for renaming. */
483 find_referenced_vars_in (gimple stmt)
487 if (gimple_code (stmt) != GIMPLE_PHI)
489 for (i = 0; i < gimple_num_ops (stmt); i++)
490 walk_tree (gimple_op_ptr (stmt, i), find_vars_r, NULL, NULL);
494 walk_tree (gimple_phi_result_ptr (stmt), find_vars_r, NULL, NULL);
496 for (i = 0; i < gimple_phi_num_args (stmt); i++)
498 tree arg = gimple_phi_arg_def (stmt, i);
499 walk_tree (&arg, find_vars_r, NULL, NULL);
505 /* Lookup UID in the referenced_vars hashtable and return the associated
509 referenced_var_lookup (unsigned int uid)
512 struct tree_decl_minimal in;
514 h = (tree) htab_find_with_hash (gimple_referenced_vars (cfun), &in, uid);
515 gcc_assert (h || uid == 0);
519 /* Check if TO is in the referenced_vars hash table and insert it if not.
520 Return true if it required insertion. */
523 referenced_var_check_and_insert (tree to)
526 struct tree_decl_minimal in;
527 unsigned int uid = DECL_UID (to);
530 h = (tree) htab_find_with_hash (gimple_referenced_vars (cfun), &in, uid);
533 /* DECL_UID has already been entered in the table. Verify that it is
534 the same entry as TO. See PR 27793. */
535 gcc_assert (h == to);
539 loc = (tree *) htab_find_slot_with_hash (gimple_referenced_vars (cfun),
545 /* Lookup VAR UID in the default_defs hashtable and return the associated
549 gimple_default_def (struct function *fn, tree var)
551 struct tree_decl_minimal ind;
552 struct tree_ssa_name in;
553 gcc_assert (SSA_VAR_P (var));
555 ind.uid = DECL_UID (var);
556 return (tree) htab_find_with_hash (DEFAULT_DEFS (fn), &in, DECL_UID (var));
559 /* Insert the pair VAR's UID, DEF into the default_defs hashtable. */
562 set_default_def (tree var, tree def)
564 struct tree_decl_minimal ind;
565 struct tree_ssa_name in;
568 gcc_assert (SSA_VAR_P (var));
570 ind.uid = DECL_UID (var);
573 loc = htab_find_slot_with_hash (DEFAULT_DEFS (cfun), &in,
574 DECL_UID (var), INSERT);
576 htab_remove_elt (DEFAULT_DEFS (cfun), *loc);
579 gcc_assert (TREE_CODE (def) == SSA_NAME && SSA_NAME_VAR (def) == var);
580 loc = htab_find_slot_with_hash (DEFAULT_DEFS (cfun), &in,
581 DECL_UID (var), INSERT);
583 /* Default definition might be changed by tail call optimization. */
585 SSA_NAME_IS_DEFAULT_DEF (*(tree *) loc) = false;
588 /* Mark DEF as the default definition for VAR. */
589 SSA_NAME_IS_DEFAULT_DEF (def) = true;
592 /* Add VAR to the list of referenced variables if it isn't already there. */
595 add_referenced_var (tree var)
598 gcc_assert (DECL_P (var));
600 /* Insert VAR into the referenced_vars has table if it isn't present. */
601 if (referenced_var_check_and_insert (var))
603 /* Scan DECL_INITIAL for pointer variables as they may contain
604 address arithmetic referencing the address of other
605 variables. As we are only interested in directly referenced
606 globals or referenced locals restrict this to initializers
607 than can refer to local variables. */
608 if (DECL_INITIAL (var)
609 && DECL_CONTEXT (var) == current_function_decl)
610 walk_tree (&DECL_INITIAL (var), find_vars_r, NULL, 0);
618 /* Remove VAR from the list. */
621 remove_referenced_var (tree var)
624 struct tree_decl_minimal in;
626 unsigned int uid = DECL_UID (var);
628 /* Preserve var_anns of globals. */
629 if (!is_global_var (var)
630 && (v_ann = var_ann (var)))
633 *DECL_VAR_ANN_PTR (var) = NULL;
635 gcc_assert (DECL_P (var));
637 loc = htab_find_slot_with_hash (gimple_referenced_vars (cfun), &in, uid,
639 htab_clear_slot (gimple_referenced_vars (cfun), loc);
643 /* Return the virtual variable associated to the non-scalar variable VAR. */
646 get_virtual_var (tree var)
650 if (TREE_CODE (var) == SSA_NAME)
651 var = SSA_NAME_VAR (var);
653 while (TREE_CODE (var) == REALPART_EXPR || TREE_CODE (var) == IMAGPART_EXPR
654 || handled_component_p (var))
655 var = TREE_OPERAND (var, 0);
657 /* Treating GIMPLE registers as virtual variables makes no sense.
658 Also complain if we couldn't extract a _DECL out of the original
660 gcc_assert (SSA_VAR_P (var));
661 gcc_assert (!is_gimple_reg (var));
666 /* Mark all the naked symbols in STMT for SSA renaming. */
669 mark_symbols_for_renaming (gimple stmt)
676 /* Mark all the operands for renaming. */
677 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_OPERANDS)
679 mark_sym_for_renaming (op);
683 /* Find all variables within the gimplified statement that were not
684 previously visible to the function and add them to the referenced
688 find_new_referenced_vars_1 (tree *tp, int *walk_subtrees,
689 void *data ATTRIBUTE_UNUSED)
693 if (TREE_CODE (t) == VAR_DECL && !var_ann (t))
695 add_referenced_var (t);
696 mark_sym_for_renaming (t);
699 if (IS_TYPE_OR_DECL_P (t))
706 /* Find any new referenced variables in STMT. */
709 find_new_referenced_vars (gimple stmt)
711 walk_gimple_op (stmt, find_new_referenced_vars_1, NULL);
715 /* If EXP is a handled component reference for a structure, return the
716 base variable. The access range is delimited by bit positions *POFFSET and
717 *POFFSET + *PMAX_SIZE. The access size is *PSIZE bits. If either
718 *PSIZE or *PMAX_SIZE is -1, they could not be determined. If *PSIZE
719 and *PMAX_SIZE are equal, the access is non-variable. */
722 get_ref_base_and_extent (tree exp, HOST_WIDE_INT *poffset,
723 HOST_WIDE_INT *psize,
724 HOST_WIDE_INT *pmax_size)
726 HOST_WIDE_INT bitsize = -1;
727 HOST_WIDE_INT maxsize = -1;
728 tree size_tree = NULL_TREE;
729 HOST_WIDE_INT bit_offset = 0;
730 bool seen_variable_array_ref = false;
732 /* First get the final access size from just the outermost expression. */
733 if (TREE_CODE (exp) == COMPONENT_REF)
734 size_tree = DECL_SIZE (TREE_OPERAND (exp, 1));
735 else if (TREE_CODE (exp) == BIT_FIELD_REF)
736 size_tree = TREE_OPERAND (exp, 1);
737 else if (!VOID_TYPE_P (TREE_TYPE (exp)))
739 enum machine_mode mode = TYPE_MODE (TREE_TYPE (exp));
741 size_tree = TYPE_SIZE (TREE_TYPE (exp));
743 bitsize = GET_MODE_BITSIZE (mode);
745 if (size_tree != NULL_TREE)
747 if (! host_integerp (size_tree, 1))
750 bitsize = TREE_INT_CST_LOW (size_tree);
753 /* Initially, maxsize is the same as the accessed element size.
754 In the following it will only grow (or become -1). */
757 /* Compute cumulative bit-offset for nested component-refs and array-refs,
758 and find the ultimate containing object. */
761 switch (TREE_CODE (exp))
764 bit_offset += TREE_INT_CST_LOW (TREE_OPERAND (exp, 2));
769 tree field = TREE_OPERAND (exp, 1);
770 tree this_offset = component_ref_field_offset (exp);
773 && TREE_CODE (this_offset) == INTEGER_CST
774 && host_integerp (this_offset, 0))
776 HOST_WIDE_INT hthis_offset = TREE_INT_CST_LOW (this_offset);
777 hthis_offset *= BITS_PER_UNIT;
779 += TREE_INT_CST_LOW (DECL_FIELD_BIT_OFFSET (field));
780 bit_offset += hthis_offset;
782 /* If we had seen a variable array ref already and we just
783 referenced the last field of a struct or a union member
784 then we have to adjust maxsize by the padding at the end
786 if (seen_variable_array_ref
789 tree stype = TREE_TYPE (TREE_OPERAND (exp, 0));
790 tree next = TREE_CHAIN (field);
791 while (next && TREE_CODE (next) != FIELD_DECL)
792 next = TREE_CHAIN (next);
794 || TREE_CODE (stype) != RECORD_TYPE)
796 tree fsize = DECL_SIZE_UNIT (field);
797 tree ssize = TYPE_SIZE_UNIT (stype);
798 if (host_integerp (fsize, 0)
799 && host_integerp (ssize, 0))
800 maxsize += ((TREE_INT_CST_LOW (ssize)
801 - TREE_INT_CST_LOW (fsize))
802 * BITS_PER_UNIT - hthis_offset);
810 tree csize = TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp, 0)));
811 /* We need to adjust maxsize to the whole structure bitsize.
812 But we can subtract any constant offset seen so far,
813 because that would get us out of the structure otherwise. */
814 if (maxsize != -1 && csize && host_integerp (csize, 1))
815 maxsize = TREE_INT_CST_LOW (csize) - bit_offset;
823 case ARRAY_RANGE_REF:
825 tree index = TREE_OPERAND (exp, 1);
826 tree low_bound, unit_size;
828 /* If the resulting bit-offset is constant, track it. */
829 if (TREE_CODE (index) == INTEGER_CST
830 && host_integerp (index, 0)
831 && (low_bound = array_ref_low_bound (exp),
832 host_integerp (low_bound, 0))
833 && (unit_size = array_ref_element_size (exp),
834 host_integerp (unit_size, 1)))
836 HOST_WIDE_INT hindex = TREE_INT_CST_LOW (index);
838 hindex -= TREE_INT_CST_LOW (low_bound);
839 hindex *= TREE_INT_CST_LOW (unit_size);
840 hindex *= BITS_PER_UNIT;
841 bit_offset += hindex;
843 /* An array ref with a constant index up in the structure
844 hierarchy will constrain the size of any variable array ref
845 lower in the access hierarchy. */
846 seen_variable_array_ref = false;
850 tree asize = TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp, 0)));
851 /* We need to adjust maxsize to the whole array bitsize.
852 But we can subtract any constant offset seen so far,
853 because that would get us outside of the array otherwise. */
854 if (maxsize != -1 && asize && host_integerp (asize, 1))
855 maxsize = TREE_INT_CST_LOW (asize) - bit_offset;
859 /* Remember that we have seen an array ref with a variable
861 seen_variable_array_ref = true;
870 bit_offset += bitsize;
873 case VIEW_CONVERT_EXPR:
880 exp = TREE_OPERAND (exp, 0);
884 /* We need to deal with variable arrays ending structures such as
885 struct { int length; int a[1]; } x; x.a[d]
886 struct { struct { int a; int b; } a[1]; } x; x.a[d].a
887 struct { struct { int a[1]; } a[1]; } x; x.a[0][d], x.a[d][0]
888 struct { int len; union { int a[1]; struct X x; } u; } x; x.u.a[d]
889 where we do not know maxsize for variable index accesses to
890 the array. The simplest way to conservatively deal with this
891 is to punt in the case that offset + maxsize reaches the
892 base type boundary. This needs to include possible trailing padding
893 that is there for alignment purposes.
895 That is of course only true if the base object is not a decl. */
899 /* If maxsize is unknown adjust it according to the size of the
902 && host_integerp (DECL_SIZE (exp), 1))
903 maxsize = TREE_INT_CST_LOW (DECL_SIZE (exp)) - bit_offset;
905 else if (seen_variable_array_ref
907 && (!host_integerp (TYPE_SIZE (TREE_TYPE (exp)), 1)
908 || (bit_offset + maxsize
909 == (signed) TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (exp))))))
912 /* ??? Due to negative offsets in ARRAY_REF we can end up with
913 negative bit_offset here. We might want to store a zero offset
915 *poffset = bit_offset;
917 *pmax_size = maxsize;
922 /* Returns true if STMT references an SSA_NAME that has
923 SSA_NAME_OCCURS_IN_ABNORMAL_PHI set, otherwise false. */
926 stmt_references_abnormal_ssa_name (gimple stmt)
931 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, oi, SSA_OP_USE)
933 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (use_p)))