1 /* Data flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
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. */
68 /* Local functions. */
69 static void collect_dfa_stats (struct dfa_stats_d *);
70 static tree collect_dfa_stats_r (tree *, int *, void *);
71 static tree find_vars_r (tree *, int *, void *);
74 /* Global declarations. */
76 /* Array of all variables referenced in the function. */
77 htab_t referenced_vars;
79 /* Default definition for this symbols. If set for symbol, it
80 means that the first reference to this variable in the function is a
81 USE or a VUSE. In those cases, the SSA renamer creates an SSA name
82 for this variable with an empty defining statement. */
86 /*---------------------------------------------------------------------------
87 Dataflow analysis (DFA) routines
88 ---------------------------------------------------------------------------*/
89 /* Find all the variables referenced in the function. This function
90 builds the global arrays REFERENCED_VARS and CALL_CLOBBERED_VARS.
92 Note that this function does not look for statement operands, it simply
93 determines what variables are referenced in the program and detects
94 various attributes for each variable used by alias analysis and the
98 find_referenced_vars (void)
101 block_stmt_iterator si;
104 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
106 tree *stmt_p = bsi_stmt_ptr (si);
107 walk_tree (stmt_p, find_vars_r, NULL, NULL);
113 struct tree_opt_pass pass_referenced_vars =
117 find_referenced_vars, /* execute */
120 0, /* static_pass_number */
121 TV_FIND_REFERENCED_VARS, /* tv_id */
122 PROP_gimple_leh | PROP_cfg, /* properties_required */
123 PROP_referenced_vars, /* properties_provided */
124 0, /* properties_destroyed */
125 0, /* todo_flags_start */
126 0, /* todo_flags_finish */
131 /*---------------------------------------------------------------------------
133 ---------------------------------------------------------------------------*/
134 /* Create a new annotation for a _DECL node T. */
137 create_var_ann (tree t)
142 gcc_assert (DECL_P (t));
143 gcc_assert (!t->common.ann || t->common.ann->common.type == VAR_ANN);
145 ann = GGC_NEW (struct var_ann_d);
146 memset ((void *) ann, 0, sizeof (*ann));
148 ann->common.type = VAR_ANN;
150 t->common.ann = (tree_ann_t) ann;
155 /* Create a new annotation for a FUNCTION_DECL node T. */
158 create_function_ann (tree t)
163 gcc_assert (TREE_CODE (t) == FUNCTION_DECL);
164 gcc_assert (!t->common.ann || t->common.ann->common.type == FUNCTION_ANN);
166 ann = ggc_alloc (sizeof (*ann));
167 memset ((void *) ann, 0, sizeof (*ann));
169 ann->common.type = FUNCTION_ANN;
171 t->common.ann = (tree_ann_t) ann;
176 /* Create a new annotation for a statement node T. */
179 create_stmt_ann (tree t)
183 gcc_assert (is_gimple_stmt (t));
184 gcc_assert (!t->common.ann || t->common.ann->common.type == STMT_ANN);
186 ann = GGC_NEW (struct stmt_ann_d);
187 memset ((void *) ann, 0, sizeof (*ann));
189 ann->common.type = STMT_ANN;
191 /* Since we just created the annotation, mark the statement modified. */
192 ann->modified = true;
194 t->common.ann = (tree_ann_t) ann;
199 /* Create a new annotation for a tree T. */
202 create_tree_ann (tree t)
207 gcc_assert (!t->common.ann || t->common.ann->common.type == TREE_ANN_COMMON);
209 ann = GGC_NEW (union tree_ann_d);
210 memset ((void *) ann, 0, sizeof (*ann));
212 ann->common.type = TREE_ANN_COMMON;
218 /* Build a temporary. Make sure and register it to be renamed. */
221 make_rename_temp (tree type, const char *prefix)
223 tree t = create_tmp_var (type, prefix);
225 if (TREE_CODE (type) == COMPLEX_TYPE)
226 DECL_COMPLEX_GIMPLE_REG_P (t) = 1;
230 add_referenced_var (t);
231 mark_sym_for_renaming (t);
239 /*---------------------------------------------------------------------------
241 ---------------------------------------------------------------------------*/
242 /* Dump the list of all the referenced variables in the current function to
246 dump_referenced_vars (FILE *file)
249 referenced_var_iterator rvi;
251 fprintf (file, "\nReferenced variables in %s: %u\n\n",
252 get_name (current_function_decl), (unsigned) num_referenced_vars);
254 FOR_EACH_REFERENCED_VAR (var, rvi)
256 fprintf (file, "Variable: ");
257 dump_variable (file, var);
258 fprintf (file, "\n");
263 /* Dump the list of all the referenced variables to stderr. */
266 debug_referenced_vars (void)
268 dump_referenced_vars (stderr);
272 /* Dump sub-variables for VAR to FILE. */
275 dump_subvars_for (FILE *file, tree var)
277 subvar_t sv = get_subvars_for_var (var);
282 fprintf (file, "{ ");
284 for (; sv; sv = sv->next)
286 print_generic_expr (file, sv->var, dump_flags);
294 /* Dumb sub-variables for VAR to stderr. */
297 debug_subvars_for (tree var)
299 dump_subvars_for (stderr, var);
303 /* Dump variable VAR and its may-aliases to FILE. */
306 dump_variable (FILE *file, tree var)
310 if (TREE_CODE (var) == SSA_NAME)
312 if (POINTER_TYPE_P (TREE_TYPE (var)))
313 dump_points_to_info_for (file, var);
314 var = SSA_NAME_VAR (var);
317 if (var == NULL_TREE)
319 fprintf (file, "<nil>");
323 print_generic_expr (file, var, dump_flags);
327 fprintf (file, ", UID %u", (unsigned) DECL_UID (var));
329 fprintf (file, ", ");
330 print_generic_expr (file, TREE_TYPE (var), dump_flags);
332 if (ann && ann->symbol_mem_tag)
334 fprintf (file, ", symbol memory tag: ");
335 print_generic_expr (file, ann->symbol_mem_tag, dump_flags);
338 if (ann && ann->is_aliased)
339 fprintf (file, ", is aliased");
341 if (TREE_ADDRESSABLE (var))
342 fprintf (file, ", is addressable");
344 if (is_global_var (var))
345 fprintf (file, ", is global");
347 if (TREE_THIS_VOLATILE (var))
348 fprintf (file, ", is volatile");
350 if (is_call_clobbered (var))
352 fprintf (file, ", call clobbered");
353 if (dump_flags & TDF_DETAILS)
355 var_ann_t va = var_ann (var);
356 unsigned int escape_mask = va->escape_mask;
358 fprintf (file, " (");
359 if (escape_mask & ESCAPE_STORED_IN_GLOBAL)
360 fprintf (file, ", stored in global");
361 if (escape_mask & ESCAPE_TO_ASM)
362 fprintf (file, ", goes through ASM");
363 if (escape_mask & ESCAPE_TO_CALL)
364 fprintf (file, ", passed to call");
365 if (escape_mask & ESCAPE_BAD_CAST)
366 fprintf (file, ", bad cast");
367 if (escape_mask & ESCAPE_TO_RETURN)
368 fprintf (file, ", returned from func");
369 if (escape_mask & ESCAPE_TO_PURE_CONST)
370 fprintf (file, ", passed to pure/const");
371 if (escape_mask & ESCAPE_IS_GLOBAL)
372 fprintf (file, ", is global var");
373 if (escape_mask & ESCAPE_IS_PARM)
374 fprintf (file, ", is incoming pointer");
375 if (escape_mask & ESCAPE_UNKNOWN)
376 fprintf (file, ", unknown escape");
377 fprintf (file, " )");
381 if (default_def (var))
383 fprintf (file, ", default def: ");
384 print_generic_expr (file, default_def (var), dump_flags);
387 if (may_aliases (var))
389 fprintf (file, ", may aliases: ");
390 dump_may_aliases_for (file, var);
393 if (get_subvars_for_var (var))
395 fprintf (file, ", sub-vars: ");
396 dump_subvars_for (file, var);
399 fprintf (file, "\n");
403 /* Dump variable VAR and its may-aliases to stderr. */
406 debug_variable (tree var)
408 dump_variable (stderr, var);
412 /* Dump various DFA statistics to FILE. */
415 dump_dfa_stats (FILE *file)
417 struct dfa_stats_d dfa_stats;
419 unsigned long size, total = 0;
420 const char * const fmt_str = "%-30s%-13s%12s\n";
421 const char * const fmt_str_1 = "%-30s%13lu%11lu%c\n";
422 const char * const fmt_str_3 = "%-43s%11lu%c\n";
424 = lang_hooks.decl_printable_name (current_function_decl, 2);
426 collect_dfa_stats (&dfa_stats);
428 fprintf (file, "\nDFA Statistics for %s\n\n", funcname);
430 fprintf (file, "---------------------------------------------------------\n");
431 fprintf (file, fmt_str, "", " Number of ", "Memory");
432 fprintf (file, fmt_str, "", " instances ", "used ");
433 fprintf (file, "---------------------------------------------------------\n");
435 size = num_referenced_vars * sizeof (tree);
437 fprintf (file, fmt_str_1, "Referenced variables", (unsigned long)num_referenced_vars,
438 SCALE (size), LABEL (size));
440 size = dfa_stats.num_stmt_anns * sizeof (struct stmt_ann_d);
442 fprintf (file, fmt_str_1, "Statements annotated", dfa_stats.num_stmt_anns,
443 SCALE (size), LABEL (size));
445 size = dfa_stats.num_var_anns * sizeof (struct var_ann_d);
447 fprintf (file, fmt_str_1, "Variables annotated", dfa_stats.num_var_anns,
448 SCALE (size), LABEL (size));
450 size = dfa_stats.num_uses * sizeof (tree *);
452 fprintf (file, fmt_str_1, "USE operands", dfa_stats.num_uses,
453 SCALE (size), LABEL (size));
455 size = dfa_stats.num_defs * sizeof (tree *);
457 fprintf (file, fmt_str_1, "DEF operands", dfa_stats.num_defs,
458 SCALE (size), LABEL (size));
460 size = dfa_stats.num_vuses * sizeof (tree *);
462 fprintf (file, fmt_str_1, "VUSE operands", dfa_stats.num_vuses,
463 SCALE (size), LABEL (size));
465 size = dfa_stats.num_v_may_defs * sizeof (tree *);
467 fprintf (file, fmt_str_1, "V_MAY_DEF operands", dfa_stats.num_v_may_defs,
468 SCALE (size), LABEL (size));
470 size = dfa_stats.num_v_must_defs * sizeof (tree *);
472 fprintf (file, fmt_str_1, "V_MUST_DEF operands", dfa_stats.num_v_must_defs,
473 SCALE (size), LABEL (size));
475 size = dfa_stats.num_phis * sizeof (struct tree_phi_node);
477 fprintf (file, fmt_str_1, "PHI nodes", dfa_stats.num_phis,
478 SCALE (size), LABEL (size));
480 size = dfa_stats.num_phi_args * sizeof (struct phi_arg_d);
482 fprintf (file, fmt_str_1, "PHI arguments", dfa_stats.num_phi_args,
483 SCALE (size), LABEL (size));
485 fprintf (file, "---------------------------------------------------------\n");
486 fprintf (file, fmt_str_3, "Total memory used by DFA/SSA data", SCALE (total),
488 fprintf (file, "---------------------------------------------------------\n");
489 fprintf (file, "\n");
491 if (dfa_stats.num_phis)
492 fprintf (file, "Average number of arguments per PHI node: %.1f (max: %d)\n",
493 (float) dfa_stats.num_phi_args / (float) dfa_stats.num_phis,
494 dfa_stats.max_num_phi_args);
496 fprintf (file, "\n");
500 /* Dump DFA statistics on stderr. */
503 debug_dfa_stats (void)
505 dump_dfa_stats (stderr);
509 /* Collect DFA statistics and store them in the structure pointed to by
513 collect_dfa_stats (struct dfa_stats_d *dfa_stats_p)
515 struct pointer_set_t *pset;
517 block_stmt_iterator i;
519 gcc_assert (dfa_stats_p);
521 memset ((void *)dfa_stats_p, 0, sizeof (struct dfa_stats_d));
523 /* Walk all the trees in the function counting references. Start at
524 basic block NUM_FIXED_BLOCKS, but don't stop at block boundaries. */
525 pset = pointer_set_create ();
527 for (i = bsi_start (BASIC_BLOCK (NUM_FIXED_BLOCKS));
528 !bsi_end_p (i); bsi_next (&i))
529 walk_tree (bsi_stmt_ptr (i), collect_dfa_stats_r, (void *) dfa_stats_p,
532 pointer_set_destroy (pset);
537 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
539 dfa_stats_p->num_phis++;
540 dfa_stats_p->num_phi_args += PHI_NUM_ARGS (phi);
541 if (PHI_NUM_ARGS (phi) > dfa_stats_p->max_num_phi_args)
542 dfa_stats_p->max_num_phi_args = PHI_NUM_ARGS (phi);
548 /* Callback for walk_tree to collect DFA statistics for a tree and its
552 collect_dfa_stats_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
556 struct dfa_stats_d *dfa_stats_p = (struct dfa_stats_d *)data;
560 switch (ann_type (t->common.ann))
564 dfa_stats_p->num_stmt_anns++;
565 dfa_stats_p->num_defs += NUM_SSA_OPERANDS (t, SSA_OP_DEF);
566 dfa_stats_p->num_uses += NUM_SSA_OPERANDS (t, SSA_OP_USE);
567 dfa_stats_p->num_v_may_defs += NUM_SSA_OPERANDS (t, SSA_OP_VMAYDEF);
568 dfa_stats_p->num_vuses += NUM_SSA_OPERANDS (t, SSA_OP_VUSE);
569 dfa_stats_p->num_v_must_defs +=
570 NUM_SSA_OPERANDS (t, SSA_OP_VMUSTDEF);
575 dfa_stats_p->num_var_anns++;
587 /*---------------------------------------------------------------------------
588 Miscellaneous helpers
589 ---------------------------------------------------------------------------*/
590 /* Callback for walk_tree. Used to collect variables referenced in
594 find_vars_r (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
596 /* If T is a regular variable that the optimizers are interested
597 in, add it to the list of variables. */
599 add_referenced_var (*tp);
601 /* Type, _DECL and constant nodes have no interesting children.
603 else if (IS_TYPE_OR_DECL_P (*tp) || CONSTANT_CLASS_P (*tp))
609 /* Lookup UID in the referenced_vars hashtable and return the associated
613 referenced_var_lookup (unsigned int uid)
615 struct int_tree_map *h, in;
617 h = (struct int_tree_map *) htab_find_with_hash (referenced_vars, &in, uid);
618 gcc_assert (h || uid == 0);
624 /* Check if TO is in the referenced_vars hash table and insert it if not.
625 Return true if it required insertion. */
628 referenced_var_check_and_insert (tree to)
630 struct int_tree_map *h, in;
632 unsigned int uid = DECL_UID (to);
636 h = (struct int_tree_map *) htab_find_with_hash (referenced_vars, &in, uid);
640 /* DECL_UID has already been entered in the table. Verify that it is
641 the same entry as TO. See PR 27793. */
642 gcc_assert (h->to == to);
646 h = GGC_NEW (struct int_tree_map);
649 loc = htab_find_slot_with_hash (referenced_vars, h, uid, INSERT);
650 *(struct int_tree_map **) loc = h;
654 /* Lookup VAR UID in the default_defs hashtable and return the associated
658 default_def (tree var)
660 struct int_tree_map *h, in;
661 gcc_assert (SSA_VAR_P (var));
662 in.uid = DECL_UID (var);
663 h = (struct int_tree_map *) htab_find_with_hash (default_defs, &in,
670 /* Insert the pair VAR's UID, DEF into the default_defs hashtable. */
673 set_default_def (tree var, tree def)
675 struct int_tree_map in;
676 struct int_tree_map *h;
679 gcc_assert (SSA_VAR_P (var));
680 in.uid = DECL_UID (var);
681 if (!def && default_def (var))
683 loc = htab_find_slot_with_hash (default_defs, &in, DECL_UID (var), INSERT);
684 htab_remove_elt (default_defs, *loc);
687 gcc_assert (TREE_CODE (def) == SSA_NAME);
688 loc = htab_find_slot_with_hash (default_defs, &in, DECL_UID (var), INSERT);
689 /* Default definition might be changed by tail call optimization. */
692 h = GGC_NEW (struct int_tree_map);
693 h->uid = DECL_UID (var);
695 *(struct int_tree_map **) loc = h;
699 h = (struct int_tree_map *) *loc;
704 /* Add VAR to the list of referenced variables if it isn't already there. */
707 add_referenced_var (tree var)
711 v_ann = get_var_ann (var);
712 gcc_assert (DECL_P (var));
714 /* Insert VAR into the referenced_vars has table if it isn't present. */
715 if (referenced_var_check_and_insert (var))
717 /* This is the first time we found this variable, annotate it with
718 attributes that are intrinsic to the variable. */
720 /* Tag's don't have DECL_INITIAL. */
724 /* Scan DECL_INITIAL for pointer variables as they may contain
725 address arithmetic referencing the address of other
727 if (DECL_INITIAL (var)
728 /* Initializers of external variables are not useful to the
730 && !DECL_EXTERNAL (var)
731 /* It's not necessary to walk the initial value of non-constant
732 variables because it cannot be propagated by the
734 && (TREE_CONSTANT (var) || TREE_READONLY (var)))
735 walk_tree (&DECL_INITIAL (var), find_vars_r, NULL, 0);
740 /* Return the virtual variable associated to the non-scalar variable VAR. */
743 get_virtual_var (tree var)
747 if (TREE_CODE (var) == SSA_NAME)
748 var = SSA_NAME_VAR (var);
750 while (TREE_CODE (var) == REALPART_EXPR || TREE_CODE (var) == IMAGPART_EXPR
751 || handled_component_p (var))
752 var = TREE_OPERAND (var, 0);
754 /* Treating GIMPLE registers as virtual variables makes no sense.
755 Also complain if we couldn't extract a _DECL out of the original
757 gcc_assert (SSA_VAR_P (var));
758 gcc_assert (!is_gimple_reg (var));
763 /* Mark all the non-SSA variables found in STMT's operands to be
764 processed by update_ssa. */
767 mark_new_vars_to_rename (tree stmt)
771 bitmap vars_in_vops_to_rename;
772 bool found_exposed_symbol = false;
773 int v_may_defs_before, v_may_defs_after;
774 int v_must_defs_before, v_must_defs_after;
776 if (TREE_CODE (stmt) == PHI_NODE)
780 vars_in_vops_to_rename = BITMAP_ALLOC (NULL);
782 /* Before re-scanning the statement for operands, mark the existing
783 virtual operands to be renamed again. We do this because when new
784 symbols are exposed, the virtual operands that were here before due to
785 aliasing will probably be removed by the call to get_stmt_operand.
786 Therefore, we need to flag them to be renamed beforehand.
788 We flag them in a separate bitmap because we don't really want to
789 rename them if there are not any newly exposed symbols in the
790 statement operands. */
791 v_may_defs_before = NUM_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF);
792 v_must_defs_before = NUM_SSA_OPERANDS (stmt, SSA_OP_VMUSTDEF);
794 FOR_EACH_SSA_TREE_OPERAND (val, stmt, iter,
795 SSA_OP_VMAYDEF | SSA_OP_VUSE | SSA_OP_VMUSTDEF)
798 val = SSA_NAME_VAR (val);
799 bitmap_set_bit (vars_in_vops_to_rename, DECL_UID (val));
802 /* Now force an operand re-scan on the statement and mark any newly
803 exposed variables. */
806 v_may_defs_after = NUM_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF);
807 v_must_defs_after = NUM_SSA_OPERANDS (stmt, SSA_OP_VMUSTDEF);
809 FOR_EACH_SSA_TREE_OPERAND (val, stmt, iter, SSA_OP_ALL_OPERANDS)
812 found_exposed_symbol = true;
813 mark_sym_for_renaming (val);
816 /* If we found any newly exposed symbols, or if there are fewer VDEF
817 operands in the statement, add the variables we had set in
818 VARS_IN_VOPS_TO_RENAME to VARS_TO_RENAME. We need to check for
819 vanishing VDEFs because in those cases, the names that were formerly
820 generated by this statement are not going to be available anymore. */
821 if (found_exposed_symbol
822 || v_may_defs_before > v_may_defs_after
823 || v_must_defs_before > v_must_defs_after)
824 mark_set_for_renaming (vars_in_vops_to_rename);
826 BITMAP_FREE (vars_in_vops_to_rename);
829 /* Find all variables within the gimplified statement that were not previously
830 visible to the function and add them to the referenced variables list. */
833 find_new_referenced_vars_1 (tree *tp, int *walk_subtrees,
834 void *data ATTRIBUTE_UNUSED)
838 if (TREE_CODE (t) == VAR_DECL && !var_ann (t))
840 add_referenced_var (t);
841 mark_sym_for_renaming (t);
844 if (IS_TYPE_OR_DECL_P (t))
851 find_new_referenced_vars (tree *stmt_p)
853 walk_tree (stmt_p, find_new_referenced_vars_1, NULL, NULL);
857 /* If REF is a handled component reference for a structure, return the
858 base variable. The access range is delimited by bit positions *POFFSET and
859 *POFFSET + *PMAX_SIZE. The access size is *PSIZE bits. If either
860 *PSIZE or *PMAX_SIZE is -1, they could not be determined. If *PSIZE
861 and *PMAX_SIZE are equal, the access is non-variable. */
864 get_ref_base_and_extent (tree exp, HOST_WIDE_INT *poffset,
865 HOST_WIDE_INT *psize,
866 HOST_WIDE_INT *pmax_size)
868 HOST_WIDE_INT bitsize = -1;
869 HOST_WIDE_INT maxsize = -1;
870 tree size_tree = NULL_TREE;
871 tree bit_offset = bitsize_zero_node;
872 bool seen_variable_array_ref = false;
874 gcc_assert (!SSA_VAR_P (exp));
876 /* First get the final access size from just the outermost expression. */
877 if (TREE_CODE (exp) == COMPONENT_REF)
878 size_tree = DECL_SIZE (TREE_OPERAND (exp, 1));
879 else if (TREE_CODE (exp) == BIT_FIELD_REF)
880 size_tree = TREE_OPERAND (exp, 1);
883 enum machine_mode mode = TYPE_MODE (TREE_TYPE (exp));
885 size_tree = TYPE_SIZE (TREE_TYPE (exp));
887 bitsize = GET_MODE_BITSIZE (mode);
889 if (size_tree != NULL_TREE)
891 if (! host_integerp (size_tree, 1))
894 bitsize = TREE_INT_CST_LOW (size_tree);
897 /* Initially, maxsize is the same as the accessed element size.
898 In the following it will only grow (or become -1). */
901 /* Compute cumulative bit-offset for nested component-refs and array-refs,
902 and find the ultimate containing object. */
905 switch (TREE_CODE (exp))
908 bit_offset = size_binop (PLUS_EXPR, bit_offset,
909 TREE_OPERAND (exp, 2));
914 tree field = TREE_OPERAND (exp, 1);
915 tree this_offset = component_ref_field_offset (exp);
917 if (this_offset && TREE_CODE (this_offset) == INTEGER_CST)
919 this_offset = size_binop (MULT_EXPR,
920 fold_convert (bitsizetype,
923 bit_offset = size_binop (PLUS_EXPR,
924 bit_offset, this_offset);
925 bit_offset = size_binop (PLUS_EXPR, bit_offset,
926 DECL_FIELD_BIT_OFFSET (field));
930 tree csize = TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp, 0)));
931 /* We need to adjust maxsize to the whole structure bitsize.
932 But we can subtract any constant offset seen sofar,
933 because that would get us out of the structure otherwise. */
935 && csize && host_integerp (csize, 1))
937 maxsize = (TREE_INT_CST_LOW (csize)
938 - TREE_INT_CST_LOW (bit_offset));
947 case ARRAY_RANGE_REF:
949 tree index = TREE_OPERAND (exp, 1);
950 tree low_bound = array_ref_low_bound (exp);
951 tree unit_size = array_ref_element_size (exp);
953 if (! integer_zerop (low_bound))
954 index = fold_build2 (MINUS_EXPR, TREE_TYPE (index),
956 index = size_binop (MULT_EXPR,
957 fold_convert (sizetype, index), unit_size);
958 if (TREE_CODE (index) == INTEGER_CST)
960 index = size_binop (MULT_EXPR,
961 fold_convert (bitsizetype, index),
963 bit_offset = size_binop (PLUS_EXPR, bit_offset, index);
965 /* An array ref with a constant index up in the structure
966 hierarchy will constrain the size of any variable array ref
967 lower in the access hierarchy. */
968 seen_variable_array_ref = false;
972 tree asize = TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp, 0)));
973 /* We need to adjust maxsize to the whole array bitsize.
974 But we can subtract any constant offset seen sofar,
975 because that would get us outside of the array otherwise. */
977 && asize && host_integerp (asize, 1))
979 maxsize = (TREE_INT_CST_LOW (asize)
980 - TREE_INT_CST_LOW (bit_offset));
985 /* Remember that we have seen an array ref with a variable
987 seen_variable_array_ref = true;
996 bit_offset = size_binop (PLUS_EXPR, bit_offset,
997 bitsize_int (bitsize));
1000 case VIEW_CONVERT_EXPR:
1001 /* ??? We probably should give up here and bail out. */
1008 exp = TREE_OPERAND (exp, 0);
1012 /* We need to deal with variable arrays ending structures such as
1013 struct { int length; int a[1]; } x; x.a[d]
1014 struct { struct { int a; int b; } a[1]; } x; x.a[d].a
1015 struct { struct { int a[1]; } a[1]; } x; x.a[0][d], x.a[d][0]
1016 where we do not know maxsize for variable index accesses to
1017 the array. The simplest way to conservatively deal with this
1018 is to punt in the case that offset + maxsize reaches the
1019 base type boundary. */
1020 if (seen_variable_array_ref
1022 && host_integerp (TYPE_SIZE (TREE_TYPE (exp)), 1)
1023 && TREE_INT_CST_LOW (bit_offset) + maxsize
1024 == TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (exp))))
1027 /* ??? Due to negative offsets in ARRAY_REF we can end up with
1028 negative bit_offset here. We might want to store a zero offset
1030 *poffset = TREE_INT_CST_LOW (bit_offset);
1032 *pmax_size = maxsize;