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_var (type, prefix);
198 if (TREE_CODE (TREE_TYPE (t)) == COMPLEX_TYPE
199 || TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
200 DECL_GIMPLE_REG_P (t) = 1;
202 if (gimple_referenced_vars (cfun))
204 add_referenced_var (t);
205 mark_sym_for_renaming (t);
213 /*---------------------------------------------------------------------------
215 ---------------------------------------------------------------------------*/
216 /* Dump the list of all the referenced variables in the current function to
220 dump_referenced_vars (FILE *file)
223 referenced_var_iterator rvi;
225 fprintf (file, "\nReferenced variables in %s: %u\n\n",
226 get_name (current_function_decl), (unsigned) num_referenced_vars);
228 FOR_EACH_REFERENCED_VAR (var, rvi)
230 fprintf (file, "Variable: ");
231 dump_variable (file, var);
234 fprintf (file, "\n");
238 /* Dump the list of all the referenced variables to stderr. */
241 debug_referenced_vars (void)
243 dump_referenced_vars (stderr);
247 /* Dump variable VAR and its may-aliases to FILE. */
250 dump_variable (FILE *file, tree var)
254 if (TREE_CODE (var) == SSA_NAME)
256 if (POINTER_TYPE_P (TREE_TYPE (var)))
257 dump_points_to_info_for (file, var);
258 var = SSA_NAME_VAR (var);
261 if (var == NULL_TREE)
263 fprintf (file, "<nil>");
267 print_generic_expr (file, var, dump_flags);
271 fprintf (file, ", UID D.%u", (unsigned) DECL_UID (var));
273 fprintf (file, ", ");
274 print_generic_expr (file, TREE_TYPE (var), dump_flags);
276 if (TREE_ADDRESSABLE (var))
277 fprintf (file, ", is addressable");
279 if (is_global_var (var))
280 fprintf (file, ", is global");
282 if (TREE_THIS_VOLATILE (var))
283 fprintf (file, ", is volatile");
285 if (is_call_clobbered (var))
286 fprintf (file, ", call clobbered");
287 else if (is_call_used (var))
288 fprintf (file, ", call used");
290 if (ann && ann->noalias_state == NO_ALIAS)
291 fprintf (file, ", NO_ALIAS (does not alias other NO_ALIAS symbols)");
292 else if (ann && ann->noalias_state == NO_ALIAS_GLOBAL)
293 fprintf (file, ", NO_ALIAS_GLOBAL (does not alias other NO_ALIAS symbols"
294 " and global vars)");
295 else if (ann && ann->noalias_state == NO_ALIAS_ANYTHING)
296 fprintf (file, ", NO_ALIAS_ANYTHING (does not alias any other symbols)");
298 if (cfun && gimple_default_def (cfun, var))
300 fprintf (file, ", default def: ");
301 print_generic_expr (file, gimple_default_def (cfun, var), dump_flags);
304 if (DECL_INITIAL (var))
306 fprintf (file, ", initial: ");
307 print_generic_expr (file, DECL_INITIAL (var), dump_flags);
310 fprintf (file, "\n");
314 /* Dump variable VAR and its may-aliases to stderr. */
317 debug_variable (tree var)
319 dump_variable (stderr, var);
323 /* Dump various DFA statistics to FILE. */
326 dump_dfa_stats (FILE *file)
328 struct dfa_stats_d dfa_stats;
330 unsigned long size, total = 0;
331 const char * const fmt_str = "%-30s%-13s%12s\n";
332 const char * const fmt_str_1 = "%-30s%13lu%11lu%c\n";
333 const char * const fmt_str_3 = "%-43s%11lu%c\n";
335 = lang_hooks.decl_printable_name (current_function_decl, 2);
337 collect_dfa_stats (&dfa_stats);
339 fprintf (file, "\nDFA Statistics for %s\n\n", funcname);
341 fprintf (file, "---------------------------------------------------------\n");
342 fprintf (file, fmt_str, "", " Number of ", "Memory");
343 fprintf (file, fmt_str, "", " instances ", "used ");
344 fprintf (file, "---------------------------------------------------------\n");
346 size = num_referenced_vars * sizeof (tree);
348 fprintf (file, fmt_str_1, "Referenced variables", (unsigned long)num_referenced_vars,
349 SCALE (size), LABEL (size));
351 size = dfa_stats.num_var_anns * sizeof (struct var_ann_d);
353 fprintf (file, fmt_str_1, "Variables annotated", dfa_stats.num_var_anns,
354 SCALE (size), LABEL (size));
356 size = dfa_stats.num_uses * sizeof (tree *);
358 fprintf (file, fmt_str_1, "USE operands", dfa_stats.num_uses,
359 SCALE (size), LABEL (size));
361 size = dfa_stats.num_defs * sizeof (tree *);
363 fprintf (file, fmt_str_1, "DEF operands", dfa_stats.num_defs,
364 SCALE (size), LABEL (size));
366 size = dfa_stats.num_vuses * sizeof (tree *);
368 fprintf (file, fmt_str_1, "VUSE operands", dfa_stats.num_vuses,
369 SCALE (size), LABEL (size));
371 size = dfa_stats.num_vdefs * sizeof (tree *);
373 fprintf (file, fmt_str_1, "VDEF operands", dfa_stats.num_vdefs,
374 SCALE (size), LABEL (size));
376 size = dfa_stats.num_phis * sizeof (struct gimple_statement_phi);
378 fprintf (file, fmt_str_1, "PHI nodes", dfa_stats.num_phis,
379 SCALE (size), LABEL (size));
381 size = dfa_stats.num_phi_args * sizeof (struct phi_arg_d);
383 fprintf (file, fmt_str_1, "PHI arguments", dfa_stats.num_phi_args,
384 SCALE (size), LABEL (size));
386 fprintf (file, "---------------------------------------------------------\n");
387 fprintf (file, fmt_str_3, "Total memory used by DFA/SSA data", SCALE (total),
389 fprintf (file, "---------------------------------------------------------\n");
390 fprintf (file, "\n");
392 if (dfa_stats.num_phis)
393 fprintf (file, "Average number of arguments per PHI node: %.1f (max: %ld)\n",
394 (float) dfa_stats.num_phi_args / (float) dfa_stats.num_phis,
395 (long) dfa_stats.max_num_phi_args);
397 fprintf (file, "\n");
401 /* Dump DFA statistics on stderr. */
404 debug_dfa_stats (void)
406 dump_dfa_stats (stderr);
410 /* Collect DFA statistics and store them in the structure pointed to by
414 collect_dfa_stats (struct dfa_stats_d *dfa_stats_p ATTRIBUTE_UNUSED)
417 referenced_var_iterator vi;
420 gcc_assert (dfa_stats_p);
422 memset ((void *)dfa_stats_p, 0, sizeof (struct dfa_stats_d));
424 /* Count all the variable annotations. */
425 FOR_EACH_REFERENCED_VAR (var, vi)
427 dfa_stats_p->num_var_anns++;
429 /* Walk all the statements in the function counting references. */
432 gimple_stmt_iterator si;
434 for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
436 gimple phi = gsi_stmt (si);
437 dfa_stats_p->num_phis++;
438 dfa_stats_p->num_phi_args += gimple_phi_num_args (phi);
439 if (gimple_phi_num_args (phi) > dfa_stats_p->max_num_phi_args)
440 dfa_stats_p->max_num_phi_args = gimple_phi_num_args (phi);
443 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
445 gimple stmt = gsi_stmt (si);
446 dfa_stats_p->num_defs += NUM_SSA_OPERANDS (stmt, SSA_OP_DEF);
447 dfa_stats_p->num_uses += NUM_SSA_OPERANDS (stmt, SSA_OP_USE);
448 dfa_stats_p->num_vdefs += gimple_vdef (stmt) ? 1 : 0;
449 dfa_stats_p->num_vuses += gimple_vuse (stmt) ? 1 : 0;
455 /*---------------------------------------------------------------------------
456 Miscellaneous helpers
457 ---------------------------------------------------------------------------*/
458 /* Callback for walk_tree. Used to collect variables referenced in
462 find_vars_r (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
464 /* If we are reading the lto info back in, we need to rescan the
466 if (TREE_CODE (*tp) == SSA_NAME)
467 add_referenced_var (SSA_NAME_VAR (*tp));
469 /* If T is a regular variable that the optimizers are interested
470 in, add it to the list of variables. */
471 else if (SSA_VAR_P (*tp))
472 add_referenced_var (*tp);
474 /* Type, _DECL and constant nodes have no interesting children.
476 else if (IS_TYPE_OR_DECL_P (*tp) || CONSTANT_CLASS_P (*tp))
482 /* Find referenced variables in STMT. In contrast with
483 find_new_referenced_vars, this function will not mark newly found
484 variables for renaming. */
487 find_referenced_vars_in (gimple stmt)
491 if (gimple_code (stmt) != GIMPLE_PHI)
493 for (i = 0; i < gimple_num_ops (stmt); i++)
494 walk_tree (gimple_op_ptr (stmt, i), find_vars_r, NULL, NULL);
498 walk_tree (gimple_phi_result_ptr (stmt), find_vars_r, NULL, NULL);
500 for (i = 0; i < gimple_phi_num_args (stmt); i++)
502 tree arg = gimple_phi_arg_def (stmt, i);
503 walk_tree (&arg, find_vars_r, NULL, NULL);
509 /* Lookup UID in the referenced_vars hashtable and return the associated
513 referenced_var_lookup (unsigned int uid)
516 struct tree_decl_minimal in;
518 h = (tree) htab_find_with_hash (gimple_referenced_vars (cfun), &in, uid);
519 gcc_assert (h || uid == 0);
523 /* Check if TO is in the referenced_vars hash table and insert it if not.
524 Return true if it required insertion. */
527 referenced_var_check_and_insert (tree to)
530 struct tree_decl_minimal in;
531 unsigned int uid = DECL_UID (to);
534 h = (tree) htab_find_with_hash (gimple_referenced_vars (cfun), &in, uid);
537 /* DECL_UID has already been entered in the table. Verify that it is
538 the same entry as TO. See PR 27793. */
539 gcc_assert (h == to);
543 loc = (tree *) htab_find_slot_with_hash (gimple_referenced_vars (cfun),
549 /* Lookup VAR UID in the default_defs hashtable and return the associated
553 gimple_default_def (struct function *fn, tree var)
555 struct tree_decl_minimal ind;
556 struct tree_ssa_name in;
557 gcc_assert (SSA_VAR_P (var));
559 ind.uid = DECL_UID (var);
560 return (tree) htab_find_with_hash (DEFAULT_DEFS (fn), &in, DECL_UID (var));
563 /* Insert the pair VAR's UID, DEF into the default_defs hashtable. */
566 set_default_def (tree var, tree def)
568 struct tree_decl_minimal ind;
569 struct tree_ssa_name in;
572 gcc_assert (SSA_VAR_P (var));
574 ind.uid = DECL_UID (var);
577 loc = htab_find_slot_with_hash (DEFAULT_DEFS (cfun), &in,
578 DECL_UID (var), INSERT);
580 htab_remove_elt (DEFAULT_DEFS (cfun), *loc);
583 gcc_assert (TREE_CODE (def) == SSA_NAME && SSA_NAME_VAR (def) == var);
584 loc = htab_find_slot_with_hash (DEFAULT_DEFS (cfun), &in,
585 DECL_UID (var), INSERT);
587 /* Default definition might be changed by tail call optimization. */
589 SSA_NAME_IS_DEFAULT_DEF (*(tree *) loc) = false;
592 /* Mark DEF as the default definition for VAR. */
593 SSA_NAME_IS_DEFAULT_DEF (def) = true;
596 /* Add VAR to the list of referenced variables if it isn't already there. */
599 add_referenced_var (tree var)
603 v_ann = get_var_ann (var);
604 gcc_assert (DECL_P (var));
606 /* Insert VAR into the referenced_vars has table if it isn't present. */
607 if (referenced_var_check_and_insert (var))
609 /* Scan DECL_INITIAL for pointer variables as they may contain
610 address arithmetic referencing the address of other
611 variables. As we are only interested in directly referenced
612 globals or referenced locals restrict this to initializers
613 than can refer to local variables. */
614 if (DECL_INITIAL (var)
615 && DECL_CONTEXT (var) == current_function_decl)
616 walk_tree (&DECL_INITIAL (var), find_vars_r, NULL, 0);
624 /* Remove VAR from the list. */
627 remove_referenced_var (tree var)
630 struct tree_decl_minimal in;
632 unsigned int uid = DECL_UID (var);
634 /* Preserve var_anns of globals. */
635 if (!is_global_var (var)
636 && (v_ann = var_ann (var)))
639 *DECL_VAR_ANN_PTR (var) = NULL;
641 gcc_assert (DECL_P (var));
643 loc = htab_find_slot_with_hash (gimple_referenced_vars (cfun), &in, uid,
645 htab_clear_slot (gimple_referenced_vars (cfun), loc);
649 /* Return the virtual variable associated to the non-scalar variable VAR. */
652 get_virtual_var (tree var)
656 if (TREE_CODE (var) == SSA_NAME)
657 var = SSA_NAME_VAR (var);
659 while (TREE_CODE (var) == REALPART_EXPR || TREE_CODE (var) == IMAGPART_EXPR
660 || handled_component_p (var))
661 var = TREE_OPERAND (var, 0);
663 /* Treating GIMPLE registers as virtual variables makes no sense.
664 Also complain if we couldn't extract a _DECL out of the original
666 gcc_assert (SSA_VAR_P (var));
667 gcc_assert (!is_gimple_reg (var));
672 /* Mark all the naked symbols in STMT for SSA renaming. */
675 mark_symbols_for_renaming (gimple stmt)
682 /* Mark all the operands for renaming. */
683 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_OPERANDS)
685 mark_sym_for_renaming (op);
689 /* Find all variables within the gimplified statement that were not
690 previously visible to the function and add them to the referenced
694 find_new_referenced_vars_1 (tree *tp, int *walk_subtrees,
695 void *data ATTRIBUTE_UNUSED)
699 if (TREE_CODE (t) == VAR_DECL && !var_ann (t))
701 add_referenced_var (t);
702 mark_sym_for_renaming (t);
705 if (IS_TYPE_OR_DECL_P (t))
712 /* Find any new referenced variables in STMT. */
715 find_new_referenced_vars (gimple stmt)
717 walk_gimple_op (stmt, find_new_referenced_vars_1, NULL);
721 /* If EXP is a handled component reference for a structure, return the
722 base variable. The access range is delimited by bit positions *POFFSET and
723 *POFFSET + *PMAX_SIZE. The access size is *PSIZE bits. If either
724 *PSIZE or *PMAX_SIZE is -1, they could not be determined. If *PSIZE
725 and *PMAX_SIZE are equal, the access is non-variable. */
728 get_ref_base_and_extent (tree exp, HOST_WIDE_INT *poffset,
729 HOST_WIDE_INT *psize,
730 HOST_WIDE_INT *pmax_size)
732 HOST_WIDE_INT bitsize = -1;
733 HOST_WIDE_INT maxsize = -1;
734 tree size_tree = NULL_TREE;
735 HOST_WIDE_INT bit_offset = 0;
736 bool seen_variable_array_ref = false;
738 /* First get the final access size from just the outermost expression. */
739 if (TREE_CODE (exp) == COMPONENT_REF)
740 size_tree = DECL_SIZE (TREE_OPERAND (exp, 1));
741 else if (TREE_CODE (exp) == BIT_FIELD_REF)
742 size_tree = TREE_OPERAND (exp, 1);
743 else if (!VOID_TYPE_P (TREE_TYPE (exp)))
745 enum machine_mode mode = TYPE_MODE (TREE_TYPE (exp));
747 size_tree = TYPE_SIZE (TREE_TYPE (exp));
749 bitsize = GET_MODE_BITSIZE (mode);
751 if (size_tree != NULL_TREE)
753 if (! host_integerp (size_tree, 1))
756 bitsize = TREE_INT_CST_LOW (size_tree);
759 /* Initially, maxsize is the same as the accessed element size.
760 In the following it will only grow (or become -1). */
763 /* Compute cumulative bit-offset for nested component-refs and array-refs,
764 and find the ultimate containing object. */
767 switch (TREE_CODE (exp))
770 bit_offset += TREE_INT_CST_LOW (TREE_OPERAND (exp, 2));
775 tree field = TREE_OPERAND (exp, 1);
776 tree this_offset = component_ref_field_offset (exp);
779 && TREE_CODE (this_offset) == INTEGER_CST
780 && host_integerp (this_offset, 0))
782 HOST_WIDE_INT hthis_offset = TREE_INT_CST_LOW (this_offset);
783 hthis_offset *= BITS_PER_UNIT;
785 += TREE_INT_CST_LOW (DECL_FIELD_BIT_OFFSET (field));
786 bit_offset += hthis_offset;
788 /* If we had seen a variable array ref already and we just
789 referenced the last field of a struct or a union member
790 then we have to adjust maxsize by the padding at the end
792 if (seen_variable_array_ref
795 tree stype = TREE_TYPE (TREE_OPERAND (exp, 0));
796 tree next = TREE_CHAIN (field);
797 while (next && TREE_CODE (next) != FIELD_DECL)
798 next = TREE_CHAIN (next);
800 || TREE_CODE (stype) != RECORD_TYPE)
802 tree fsize = DECL_SIZE_UNIT (field);
803 tree ssize = TYPE_SIZE_UNIT (stype);
804 if (host_integerp (fsize, 0)
805 && host_integerp (ssize, 0))
806 maxsize += ((TREE_INT_CST_LOW (ssize)
807 - TREE_INT_CST_LOW (fsize))
808 * BITS_PER_UNIT - hthis_offset);
816 tree csize = TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp, 0)));
817 /* We need to adjust maxsize to the whole structure bitsize.
818 But we can subtract any constant offset seen so far,
819 because that would get us out of the structure otherwise. */
820 if (maxsize != -1 && csize && host_integerp (csize, 1))
821 maxsize = TREE_INT_CST_LOW (csize) - bit_offset;
829 case ARRAY_RANGE_REF:
831 tree index = TREE_OPERAND (exp, 1);
832 tree low_bound, unit_size;
834 /* If the resulting bit-offset is constant, track it. */
835 if (TREE_CODE (index) == INTEGER_CST
836 && host_integerp (index, 0)
837 && (low_bound = array_ref_low_bound (exp),
838 host_integerp (low_bound, 0))
839 && (unit_size = array_ref_element_size (exp),
840 host_integerp (unit_size, 1)))
842 HOST_WIDE_INT hindex = TREE_INT_CST_LOW (index);
844 hindex -= TREE_INT_CST_LOW (low_bound);
845 hindex *= TREE_INT_CST_LOW (unit_size);
846 hindex *= BITS_PER_UNIT;
847 bit_offset += hindex;
849 /* An array ref with a constant index up in the structure
850 hierarchy will constrain the size of any variable array ref
851 lower in the access hierarchy. */
852 seen_variable_array_ref = false;
856 tree asize = TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp, 0)));
857 /* We need to adjust maxsize to the whole array bitsize.
858 But we can subtract any constant offset seen so far,
859 because that would get us outside of the array otherwise. */
860 if (maxsize != -1 && asize && host_integerp (asize, 1))
861 maxsize = TREE_INT_CST_LOW (asize) - bit_offset;
865 /* Remember that we have seen an array ref with a variable
867 seen_variable_array_ref = true;
876 bit_offset += bitsize;
879 case VIEW_CONVERT_EXPR:
886 exp = TREE_OPERAND (exp, 0);
890 /* We need to deal with variable arrays ending structures such as
891 struct { int length; int a[1]; } x; x.a[d]
892 struct { struct { int a; int b; } a[1]; } x; x.a[d].a
893 struct { struct { int a[1]; } a[1]; } x; x.a[0][d], x.a[d][0]
894 struct { int len; union { int a[1]; struct X x; } u; } x; x.u.a[d]
895 where we do not know maxsize for variable index accesses to
896 the array. The simplest way to conservatively deal with this
897 is to punt in the case that offset + maxsize reaches the
898 base type boundary. This needs to include possible trailing padding
899 that is there for alignment purposes.
901 That is of course only true if the base object is not a decl. */
905 /* If maxsize is unknown adjust it according to the size of the
908 && host_integerp (DECL_SIZE (exp), 1))
909 maxsize = TREE_INT_CST_LOW (DECL_SIZE (exp)) - bit_offset;
911 else if (seen_variable_array_ref
913 && (!host_integerp (TYPE_SIZE (TREE_TYPE (exp)), 1)
914 || (bit_offset + maxsize
915 == (signed) TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (exp))))))
918 /* ??? Due to negative offsets in ARRAY_REF we can end up with
919 negative bit_offset here. We might want to store a zero offset
921 *poffset = bit_offset;
923 *pmax_size = maxsize;
928 /* Returns true if STMT references an SSA_NAME that has
929 SSA_NAME_OCCURS_IN_ABNORMAL_PHI set, otherwise false. */
932 stmt_references_abnormal_ssa_name (gimple stmt)
937 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, oi, SSA_OP_USE)
939 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (use_p)))