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");
288 if (ann && ann->noalias_state == NO_ALIAS)
289 fprintf (file, ", NO_ALIAS (does not alias other NO_ALIAS symbols)");
290 else if (ann && ann->noalias_state == NO_ALIAS_GLOBAL)
291 fprintf (file, ", NO_ALIAS_GLOBAL (does not alias other NO_ALIAS symbols"
292 " and global vars)");
293 else if (ann && ann->noalias_state == NO_ALIAS_ANYTHING)
294 fprintf (file, ", NO_ALIAS_ANYTHING (does not alias any other symbols)");
296 if (cfun && gimple_default_def (cfun, var))
298 fprintf (file, ", default def: ");
299 print_generic_expr (file, gimple_default_def (cfun, var), dump_flags);
302 if (DECL_INITIAL (var))
304 fprintf (file, ", initial: ");
305 print_generic_expr (file, DECL_INITIAL (var), dump_flags);
308 fprintf (file, "\n");
312 /* Dump variable VAR and its may-aliases to stderr. */
315 debug_variable (tree var)
317 dump_variable (stderr, var);
321 /* Dump various DFA statistics to FILE. */
324 dump_dfa_stats (FILE *file)
326 struct dfa_stats_d dfa_stats;
328 unsigned long size, total = 0;
329 const char * const fmt_str = "%-30s%-13s%12s\n";
330 const char * const fmt_str_1 = "%-30s%13lu%11lu%c\n";
331 const char * const fmt_str_3 = "%-43s%11lu%c\n";
333 = lang_hooks.decl_printable_name (current_function_decl, 2);
335 collect_dfa_stats (&dfa_stats);
337 fprintf (file, "\nDFA Statistics for %s\n\n", funcname);
339 fprintf (file, "---------------------------------------------------------\n");
340 fprintf (file, fmt_str, "", " Number of ", "Memory");
341 fprintf (file, fmt_str, "", " instances ", "used ");
342 fprintf (file, "---------------------------------------------------------\n");
344 size = num_referenced_vars * sizeof (tree);
346 fprintf (file, fmt_str_1, "Referenced variables", (unsigned long)num_referenced_vars,
347 SCALE (size), LABEL (size));
349 size = dfa_stats.num_var_anns * sizeof (struct var_ann_d);
351 fprintf (file, fmt_str_1, "Variables annotated", dfa_stats.num_var_anns,
352 SCALE (size), LABEL (size));
354 size = dfa_stats.num_uses * sizeof (tree *);
356 fprintf (file, fmt_str_1, "USE operands", dfa_stats.num_uses,
357 SCALE (size), LABEL (size));
359 size = dfa_stats.num_defs * sizeof (tree *);
361 fprintf (file, fmt_str_1, "DEF operands", dfa_stats.num_defs,
362 SCALE (size), LABEL (size));
364 size = dfa_stats.num_vuses * sizeof (tree *);
366 fprintf (file, fmt_str_1, "VUSE operands", dfa_stats.num_vuses,
367 SCALE (size), LABEL (size));
369 size = dfa_stats.num_vdefs * sizeof (tree *);
371 fprintf (file, fmt_str_1, "VDEF operands", dfa_stats.num_vdefs,
372 SCALE (size), LABEL (size));
374 size = dfa_stats.num_phis * sizeof (struct gimple_statement_phi);
376 fprintf (file, fmt_str_1, "PHI nodes", dfa_stats.num_phis,
377 SCALE (size), LABEL (size));
379 size = dfa_stats.num_phi_args * sizeof (struct phi_arg_d);
381 fprintf (file, fmt_str_1, "PHI arguments", dfa_stats.num_phi_args,
382 SCALE (size), LABEL (size));
384 fprintf (file, "---------------------------------------------------------\n");
385 fprintf (file, fmt_str_3, "Total memory used by DFA/SSA data", SCALE (total),
387 fprintf (file, "---------------------------------------------------------\n");
388 fprintf (file, "\n");
390 if (dfa_stats.num_phis)
391 fprintf (file, "Average number of arguments per PHI node: %.1f (max: %ld)\n",
392 (float) dfa_stats.num_phi_args / (float) dfa_stats.num_phis,
393 (long) dfa_stats.max_num_phi_args);
395 fprintf (file, "\n");
399 /* Dump DFA statistics on stderr. */
402 debug_dfa_stats (void)
404 dump_dfa_stats (stderr);
408 /* Collect DFA statistics and store them in the structure pointed to by
412 collect_dfa_stats (struct dfa_stats_d *dfa_stats_p ATTRIBUTE_UNUSED)
415 referenced_var_iterator vi;
418 gcc_assert (dfa_stats_p);
420 memset ((void *)dfa_stats_p, 0, sizeof (struct dfa_stats_d));
422 /* Count all the variable annotations. */
423 FOR_EACH_REFERENCED_VAR (var, vi)
425 dfa_stats_p->num_var_anns++;
427 /* Walk all the statements in the function counting references. */
430 gimple_stmt_iterator si;
432 for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
434 gimple phi = gsi_stmt (si);
435 dfa_stats_p->num_phis++;
436 dfa_stats_p->num_phi_args += gimple_phi_num_args (phi);
437 if (gimple_phi_num_args (phi) > dfa_stats_p->max_num_phi_args)
438 dfa_stats_p->max_num_phi_args = gimple_phi_num_args (phi);
441 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
443 gimple stmt = gsi_stmt (si);
444 dfa_stats_p->num_defs += NUM_SSA_OPERANDS (stmt, SSA_OP_DEF);
445 dfa_stats_p->num_uses += NUM_SSA_OPERANDS (stmt, SSA_OP_USE);
446 dfa_stats_p->num_vdefs += gimple_vdef (stmt) ? 1 : 0;
447 dfa_stats_p->num_vuses += gimple_vuse (stmt) ? 1 : 0;
453 /*---------------------------------------------------------------------------
454 Miscellaneous helpers
455 ---------------------------------------------------------------------------*/
456 /* Callback for walk_tree. Used to collect variables referenced in
460 find_vars_r (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
462 /* If we are reading the lto info back in, we need to rescan the
464 if (TREE_CODE (*tp) == SSA_NAME)
465 add_referenced_var (SSA_NAME_VAR (*tp));
467 /* If T is a regular variable that the optimizers are interested
468 in, add it to the list of variables. */
469 else if (SSA_VAR_P (*tp))
470 add_referenced_var (*tp);
472 /* Type, _DECL and constant nodes have no interesting children.
474 else if (IS_TYPE_OR_DECL_P (*tp) || CONSTANT_CLASS_P (*tp))
480 /* Find referenced variables in STMT. In contrast with
481 find_new_referenced_vars, this function will not mark newly found
482 variables for renaming. */
485 find_referenced_vars_in (gimple stmt)
489 if (gimple_code (stmt) != GIMPLE_PHI)
491 for (i = 0; i < gimple_num_ops (stmt); i++)
492 walk_tree (gimple_op_ptr (stmt, i), find_vars_r, NULL, NULL);
496 walk_tree (gimple_phi_result_ptr (stmt), find_vars_r, NULL, NULL);
498 for (i = 0; i < gimple_phi_num_args (stmt); i++)
500 tree arg = gimple_phi_arg_def (stmt, i);
501 walk_tree (&arg, find_vars_r, NULL, NULL);
507 /* Lookup UID in the referenced_vars hashtable and return the associated
511 referenced_var_lookup (unsigned int uid)
514 struct tree_decl_minimal in;
516 h = (tree) htab_find_with_hash (gimple_referenced_vars (cfun), &in, uid);
517 gcc_assert (h || uid == 0);
521 /* Check if TO is in the referenced_vars hash table and insert it if not.
522 Return true if it required insertion. */
525 referenced_var_check_and_insert (tree to)
528 struct tree_decl_minimal in;
529 unsigned int uid = DECL_UID (to);
532 h = (tree) htab_find_with_hash (gimple_referenced_vars (cfun), &in, uid);
535 /* DECL_UID has already been entered in the table. Verify that it is
536 the same entry as TO. See PR 27793. */
537 gcc_assert (h == to);
541 loc = (tree *) htab_find_slot_with_hash (gimple_referenced_vars (cfun),
547 /* Lookup VAR UID in the default_defs hashtable and return the associated
551 gimple_default_def (struct function *fn, tree var)
553 struct tree_decl_minimal ind;
554 struct tree_ssa_name in;
555 gcc_assert (SSA_VAR_P (var));
557 ind.uid = DECL_UID (var);
558 return (tree) htab_find_with_hash (DEFAULT_DEFS (fn), &in, DECL_UID (var));
561 /* Insert the pair VAR's UID, DEF into the default_defs hashtable. */
564 set_default_def (tree var, tree def)
566 struct tree_decl_minimal ind;
567 struct tree_ssa_name in;
570 gcc_assert (SSA_VAR_P (var));
572 ind.uid = DECL_UID (var);
575 loc = htab_find_slot_with_hash (DEFAULT_DEFS (cfun), &in,
576 DECL_UID (var), INSERT);
578 htab_remove_elt (DEFAULT_DEFS (cfun), *loc);
581 gcc_assert (TREE_CODE (def) == SSA_NAME && SSA_NAME_VAR (def) == var);
582 loc = htab_find_slot_with_hash (DEFAULT_DEFS (cfun), &in,
583 DECL_UID (var), INSERT);
585 /* Default definition might be changed by tail call optimization. */
587 SSA_NAME_IS_DEFAULT_DEF (*(tree *) loc) = false;
590 /* Mark DEF as the default definition for VAR. */
591 SSA_NAME_IS_DEFAULT_DEF (def) = true;
594 /* Add VAR to the list of referenced variables if it isn't already there. */
597 add_referenced_var (tree var)
600 gcc_assert (DECL_P (var));
602 /* Insert VAR into the referenced_vars has table if it isn't present. */
603 if (referenced_var_check_and_insert (var))
605 /* Scan DECL_INITIAL for pointer variables as they may contain
606 address arithmetic referencing the address of other
607 variables. As we are only interested in directly referenced
608 globals or referenced locals restrict this to initializers
609 than can refer to local variables. */
610 if (DECL_INITIAL (var)
611 && DECL_CONTEXT (var) == current_function_decl)
612 walk_tree (&DECL_INITIAL (var), find_vars_r, NULL, 0);
620 /* Remove VAR from the list. */
623 remove_referenced_var (tree var)
626 struct tree_decl_minimal in;
628 unsigned int uid = DECL_UID (var);
630 /* Preserve var_anns of globals. */
631 if (!is_global_var (var)
632 && (v_ann = var_ann (var)))
635 *DECL_VAR_ANN_PTR (var) = NULL;
637 gcc_assert (DECL_P (var));
639 loc = htab_find_slot_with_hash (gimple_referenced_vars (cfun), &in, uid,
641 htab_clear_slot (gimple_referenced_vars (cfun), loc);
645 /* Return the virtual variable associated to the non-scalar variable VAR. */
648 get_virtual_var (tree var)
652 if (TREE_CODE (var) == SSA_NAME)
653 var = SSA_NAME_VAR (var);
655 while (TREE_CODE (var) == REALPART_EXPR || TREE_CODE (var) == IMAGPART_EXPR
656 || handled_component_p (var))
657 var = TREE_OPERAND (var, 0);
659 /* Treating GIMPLE registers as virtual variables makes no sense.
660 Also complain if we couldn't extract a _DECL out of the original
662 gcc_assert (SSA_VAR_P (var));
663 gcc_assert (!is_gimple_reg (var));
668 /* Mark all the naked symbols in STMT for SSA renaming. */
671 mark_symbols_for_renaming (gimple stmt)
678 /* Mark all the operands for renaming. */
679 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_OPERANDS)
681 mark_sym_for_renaming (op);
685 /* Find all variables within the gimplified statement that were not
686 previously visible to the function and add them to the referenced
690 find_new_referenced_vars_1 (tree *tp, int *walk_subtrees,
691 void *data ATTRIBUTE_UNUSED)
695 if (TREE_CODE (t) == VAR_DECL && !var_ann (t))
697 add_referenced_var (t);
698 mark_sym_for_renaming (t);
701 if (IS_TYPE_OR_DECL_P (t))
708 /* Find any new referenced variables in STMT. */
711 find_new_referenced_vars (gimple stmt)
713 walk_gimple_op (stmt, find_new_referenced_vars_1, NULL);
717 /* If EXP is a handled component reference for a structure, return the
718 base variable. The access range is delimited by bit positions *POFFSET and
719 *POFFSET + *PMAX_SIZE. The access size is *PSIZE bits. If either
720 *PSIZE or *PMAX_SIZE is -1, they could not be determined. If *PSIZE
721 and *PMAX_SIZE are equal, the access is non-variable. */
724 get_ref_base_and_extent (tree exp, HOST_WIDE_INT *poffset,
725 HOST_WIDE_INT *psize,
726 HOST_WIDE_INT *pmax_size)
728 HOST_WIDE_INT bitsize = -1;
729 HOST_WIDE_INT maxsize = -1;
730 tree size_tree = NULL_TREE;
731 HOST_WIDE_INT bit_offset = 0;
732 bool seen_variable_array_ref = false;
734 /* First get the final access size from just the outermost expression. */
735 if (TREE_CODE (exp) == COMPONENT_REF)
736 size_tree = DECL_SIZE (TREE_OPERAND (exp, 1));
737 else if (TREE_CODE (exp) == BIT_FIELD_REF)
738 size_tree = TREE_OPERAND (exp, 1);
739 else if (!VOID_TYPE_P (TREE_TYPE (exp)))
741 enum machine_mode mode = TYPE_MODE (TREE_TYPE (exp));
743 size_tree = TYPE_SIZE (TREE_TYPE (exp));
745 bitsize = GET_MODE_BITSIZE (mode);
747 if (size_tree != NULL_TREE)
749 if (! host_integerp (size_tree, 1))
752 bitsize = TREE_INT_CST_LOW (size_tree);
755 /* Initially, maxsize is the same as the accessed element size.
756 In the following it will only grow (or become -1). */
759 /* Compute cumulative bit-offset for nested component-refs and array-refs,
760 and find the ultimate containing object. */
763 switch (TREE_CODE (exp))
766 bit_offset += TREE_INT_CST_LOW (TREE_OPERAND (exp, 2));
771 tree field = TREE_OPERAND (exp, 1);
772 tree this_offset = component_ref_field_offset (exp);
775 && TREE_CODE (this_offset) == INTEGER_CST
776 && host_integerp (this_offset, 0))
778 HOST_WIDE_INT hthis_offset = TREE_INT_CST_LOW (this_offset);
779 hthis_offset *= BITS_PER_UNIT;
781 += TREE_INT_CST_LOW (DECL_FIELD_BIT_OFFSET (field));
782 bit_offset += hthis_offset;
784 /* If we had seen a variable array ref already and we just
785 referenced the last field of a struct or a union member
786 then we have to adjust maxsize by the padding at the end
788 if (seen_variable_array_ref
791 tree stype = TREE_TYPE (TREE_OPERAND (exp, 0));
792 tree next = TREE_CHAIN (field);
793 while (next && TREE_CODE (next) != FIELD_DECL)
794 next = TREE_CHAIN (next);
796 || TREE_CODE (stype) != RECORD_TYPE)
798 tree fsize = DECL_SIZE_UNIT (field);
799 tree ssize = TYPE_SIZE_UNIT (stype);
800 if (host_integerp (fsize, 0)
801 && host_integerp (ssize, 0))
802 maxsize += ((TREE_INT_CST_LOW (ssize)
803 - TREE_INT_CST_LOW (fsize))
804 * BITS_PER_UNIT - hthis_offset);
812 tree csize = TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp, 0)));
813 /* We need to adjust maxsize to the whole structure bitsize.
814 But we can subtract any constant offset seen so far,
815 because that would get us out of the structure otherwise. */
816 if (maxsize != -1 && csize && host_integerp (csize, 1))
817 maxsize = TREE_INT_CST_LOW (csize) - bit_offset;
825 case ARRAY_RANGE_REF:
827 tree index = TREE_OPERAND (exp, 1);
828 tree low_bound, unit_size;
830 /* If the resulting bit-offset is constant, track it. */
831 if (TREE_CODE (index) == INTEGER_CST
832 && host_integerp (index, 0)
833 && (low_bound = array_ref_low_bound (exp),
834 host_integerp (low_bound, 0))
835 && (unit_size = array_ref_element_size (exp),
836 host_integerp (unit_size, 1)))
838 HOST_WIDE_INT hindex = TREE_INT_CST_LOW (index);
840 hindex -= TREE_INT_CST_LOW (low_bound);
841 hindex *= TREE_INT_CST_LOW (unit_size);
842 hindex *= BITS_PER_UNIT;
843 bit_offset += hindex;
845 /* An array ref with a constant index up in the structure
846 hierarchy will constrain the size of any variable array ref
847 lower in the access hierarchy. */
848 seen_variable_array_ref = false;
852 tree asize = TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp, 0)));
853 /* We need to adjust maxsize to the whole array bitsize.
854 But we can subtract any constant offset seen so far,
855 because that would get us outside of the array otherwise. */
856 if (maxsize != -1 && asize && host_integerp (asize, 1))
857 maxsize = TREE_INT_CST_LOW (asize) - bit_offset;
861 /* Remember that we have seen an array ref with a variable
863 seen_variable_array_ref = true;
872 bit_offset += bitsize;
875 case VIEW_CONVERT_EXPR:
882 exp = TREE_OPERAND (exp, 0);
886 /* We need to deal with variable arrays ending structures such as
887 struct { int length; int a[1]; } x; x.a[d]
888 struct { struct { int a; int b; } a[1]; } x; x.a[d].a
889 struct { struct { int a[1]; } a[1]; } x; x.a[0][d], x.a[d][0]
890 struct { int len; union { int a[1]; struct X x; } u; } x; x.u.a[d]
891 where we do not know maxsize for variable index accesses to
892 the array. The simplest way to conservatively deal with this
893 is to punt in the case that offset + maxsize reaches the
894 base type boundary. This needs to include possible trailing padding
895 that is there for alignment purposes.
897 That is of course only true if the base object is not a decl. */
901 /* If maxsize is unknown adjust it according to the size of the
904 && host_integerp (DECL_SIZE (exp), 1))
905 maxsize = TREE_INT_CST_LOW (DECL_SIZE (exp)) - bit_offset;
907 else if (seen_variable_array_ref
909 && (!host_integerp (TYPE_SIZE (TREE_TYPE (exp)), 1)
910 || (bit_offset + maxsize
911 == (signed) TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (exp))))))
914 /* ??? Due to negative offsets in ARRAY_REF we can end up with
915 negative bit_offset here. We might want to store a zero offset
917 *poffset = bit_offset;
919 *pmax_size = maxsize;
924 /* Returns true if STMT references an SSA_NAME that has
925 SSA_NAME_OCCURS_IN_ABNORMAL_PHI set, otherwise false. */
928 stmt_references_abnormal_ssa_name (gimple stmt)
933 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, oi, SSA_OP_USE)
935 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (use_p)))