1 /* Miscellaneous SSA utility functions.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GCC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to
18 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
19 Boston, MA 02110-1301, USA. */
23 #include "coretypes.h"
30 #include "langhooks.h"
31 #include "hard-reg-set.h"
32 #include "basic-block.h"
36 #include "diagnostic.h"
38 #include "pointer-set.h"
39 #include "tree-flow.h"
40 #include "tree-gimple.h"
41 #include "tree-inline.h"
45 #include "tree-dump.h"
46 #include "tree-pass.h"
49 /* Remove the corresponding arguments from the PHI nodes in E's
50 destination block and redirect it to DEST. Return redirected edge.
51 The list of removed arguments is stored in PENDING_STMT (e). */
54 ssa_redirect_edge (edge e, basic_block dest)
57 tree list = NULL, *last = &list;
60 /* Remove the appropriate PHI arguments in E's destination block. */
61 for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
63 if (PHI_ARG_DEF (phi, e->dest_idx) == NULL_TREE)
66 src = PHI_ARG_DEF (phi, e->dest_idx);
67 dst = PHI_RESULT (phi);
68 node = build_tree_list (dst, src);
70 last = &TREE_CHAIN (node);
73 e = redirect_edge_succ_nodup (e, dest);
74 PENDING_STMT (e) = list;
79 /* Add PHI arguments queued in PENDINT_STMT list on edge E to edge
83 flush_pending_stmts (edge e)
87 if (!PENDING_STMT (e))
90 for (phi = phi_nodes (e->dest), arg = PENDING_STMT (e);
92 phi = PHI_CHAIN (phi), arg = TREE_CHAIN (arg))
94 tree def = TREE_VALUE (arg);
95 add_phi_arg (phi, def, e);
98 PENDING_STMT (e) = NULL;
101 /* Return true if SSA_NAME is malformed and mark it visited.
103 IS_VIRTUAL is true if this SSA_NAME was found inside a virtual
107 verify_ssa_name (tree ssa_name, bool is_virtual)
109 if (TREE_CODE (ssa_name) != SSA_NAME)
111 error ("expected an SSA_NAME object");
115 if (TREE_TYPE (ssa_name) != TREE_TYPE (SSA_NAME_VAR (ssa_name)))
117 error ("type mismatch between an SSA_NAME and its symbol");
121 if (SSA_NAME_IN_FREE_LIST (ssa_name))
123 error ("found an SSA_NAME that had been released into the free pool");
127 if (is_virtual && is_gimple_reg (ssa_name))
129 error ("found a virtual definition for a GIMPLE register");
133 if (!is_virtual && !is_gimple_reg (ssa_name))
135 error ("found a real definition for a non-register");
139 if (is_virtual && var_ann (SSA_NAME_VAR (ssa_name))
140 && get_subvars_for_var (SSA_NAME_VAR (ssa_name)) != NULL)
142 error ("found real variable when subvariables should have appeared");
150 /* Return true if the definition of SSA_NAME at block BB is malformed.
152 STMT is the statement where SSA_NAME is created.
154 DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME
155 version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set,
156 it means that the block in that array slot contains the
157 definition of SSA_NAME.
159 IS_VIRTUAL is true if SSA_NAME is created by a V_MAY_DEF or a
163 verify_def (basic_block bb, basic_block *definition_block, tree ssa_name,
164 tree stmt, bool is_virtual)
166 if (verify_ssa_name (ssa_name, is_virtual))
169 if (definition_block[SSA_NAME_VERSION (ssa_name)])
171 error ("SSA_NAME created in two different blocks %i and %i",
172 definition_block[SSA_NAME_VERSION (ssa_name)]->index, bb->index);
176 definition_block[SSA_NAME_VERSION (ssa_name)] = bb;
178 if (SSA_NAME_DEF_STMT (ssa_name) != stmt)
180 error ("SSA_NAME_DEF_STMT is wrong");
181 fprintf (stderr, "Expected definition statement:\n");
182 print_generic_stmt (stderr, SSA_NAME_DEF_STMT (ssa_name), TDF_VOPS);
183 fprintf (stderr, "\nActual definition statement:\n");
184 print_generic_stmt (stderr, stmt, TDF_VOPS);
191 fprintf (stderr, "while verifying SSA_NAME ");
192 print_generic_expr (stderr, ssa_name, 0);
193 fprintf (stderr, " in statement\n");
194 print_generic_stmt (stderr, stmt, TDF_VOPS);
200 /* Return true if the use of SSA_NAME at statement STMT in block BB is
203 DEF_BB is the block where SSA_NAME was found to be created.
205 IDOM contains immediate dominator information for the flowgraph.
207 CHECK_ABNORMAL is true if the caller wants to check whether this use
208 is flowing through an abnormal edge (only used when checking PHI
211 IS_VIRTUAL is true if SSA_NAME is created by a V_MAY_DEF or a
214 If NAMES_DEFINED_IN_BB is not NULL, it contains a bitmap of ssa names
215 that are defined before STMT in basic block BB. */
218 verify_use (basic_block bb, basic_block def_bb, use_operand_p use_p,
219 tree stmt, bool check_abnormal, bool is_virtual,
220 bitmap names_defined_in_bb)
223 tree ssa_name = USE_FROM_PTR (use_p);
225 err = verify_ssa_name (ssa_name, is_virtual);
227 if (!TREE_VISITED (ssa_name))
228 if (verify_imm_links (stderr, ssa_name))
231 TREE_VISITED (ssa_name) = 1;
233 if (IS_EMPTY_STMT (SSA_NAME_DEF_STMT (ssa_name))
234 && var_ann (SSA_NAME_VAR (ssa_name))->default_def == ssa_name)
235 ; /* Default definitions have empty statements. Nothing to do. */
238 error ("missing definition");
241 else if (bb != def_bb
242 && !dominated_by_p (CDI_DOMINATORS, bb, def_bb))
244 error ("definition in block %i does not dominate use in block %i",
245 def_bb->index, bb->index);
248 else if (bb == def_bb
249 && names_defined_in_bb != NULL
250 && !bitmap_bit_p (names_defined_in_bb, SSA_NAME_VERSION (ssa_name)))
252 error ("definition in block %i follows the use", def_bb->index);
257 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (ssa_name))
259 error ("SSA_NAME_OCCURS_IN_ABNORMAL_PHI should be set");
263 /* Make sure the use is in an appropriate list by checking the previous
264 element to make sure it's the same. */
265 if (use_p->prev == NULL)
267 error ("no immediate_use list");
273 if (use_p->prev->use == NULL)
274 listvar = use_p->prev->stmt;
276 listvar = USE_FROM_PTR (use_p->prev);
277 if (listvar != ssa_name)
279 error ("wrong immediate use list");
286 fprintf (stderr, "for SSA_NAME: ");
287 print_generic_expr (stderr, ssa_name, TDF_VOPS);
288 fprintf (stderr, " in statement:\n");
289 print_generic_stmt (stderr, stmt, TDF_VOPS);
296 /* Return true if any of the arguments for PHI node PHI at block BB is
299 DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME version
300 numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set, it means that the
301 block in that array slot contains the definition of SSA_NAME. */
304 verify_phi_args (tree phi, basic_block bb, basic_block *definition_block)
308 unsigned i, phi_num_args = PHI_NUM_ARGS (phi);
310 if (EDGE_COUNT (bb->preds) != phi_num_args)
312 error ("incoming edge count does not match number of PHI arguments");
317 for (i = 0; i < phi_num_args; i++)
319 use_operand_p op_p = PHI_ARG_DEF_PTR (phi, i);
320 tree op = USE_FROM_PTR (op_p);
323 e = EDGE_PRED (bb, i);
327 error ("PHI argument is missing for edge %d->%d",
334 if (TREE_CODE (op) != SSA_NAME && !is_gimple_min_invariant (op))
336 error ("PHI argument is not SSA_NAME, or invariant");
340 if (TREE_CODE (op) == SSA_NAME)
341 err = verify_use (e->src, definition_block[SSA_NAME_VERSION (op)], op_p,
342 phi, e->flags & EDGE_ABNORMAL,
343 !is_gimple_reg (PHI_RESULT (phi)),
348 error ("wrong edge %d->%d for PHI argument",
349 e->src->index, e->dest->index);
355 fprintf (stderr, "PHI argument\n");
356 print_generic_stmt (stderr, op, TDF_VOPS);
364 fprintf (stderr, "for PHI node\n");
365 print_generic_stmt (stderr, phi, TDF_VOPS);
374 verify_flow_insensitive_alias_info (void)
377 bitmap visited = BITMAP_ALLOC (NULL);
378 referenced_var_iterator rvi;
380 FOR_EACH_REFERENCED_VAR (var, rvi)
384 varray_type may_aliases;
387 may_aliases = ann->may_aliases;
389 for (j = 0; may_aliases && j < VARRAY_ACTIVE_SIZE (may_aliases); j++)
391 tree alias = VARRAY_TREE (may_aliases, j);
393 bitmap_set_bit (visited, DECL_UID (alias));
395 if (!may_be_aliased (alias))
397 error ("non-addressable variable inside an alias set");
398 debug_variable (alias);
404 FOR_EACH_REFERENCED_VAR (var, rvi)
409 if (ann->mem_tag_kind == NOT_A_TAG
411 && !bitmap_bit_p (visited, DECL_UID (var)))
413 error ("addressable variable that is an alias tag but is not in any alias set");
418 BITMAP_FREE (visited);
422 debug_variable (var);
423 internal_error ("verify_flow_insensitive_alias_info failed");
428 verify_flow_sensitive_alias_info (void)
433 for (i = 1; i < num_ssa_names; i++)
437 struct ptr_info_def *pi;
444 /* We only care for pointers that are actually referenced in the
446 if (!POINTER_TYPE_P (TREE_TYPE (ptr)) || !TREE_VISITED (ptr))
449 /* RESULT_DECL is special. If it's a GIMPLE register, then it
450 is only written-to only once in the return statement.
451 Otherwise, aggregate RESULT_DECLs may be written-to more than
452 once in virtual operands. */
453 var = SSA_NAME_VAR (ptr);
454 if (TREE_CODE (var) == RESULT_DECL
455 && is_gimple_reg (ptr))
458 pi = SSA_NAME_PTR_INFO (ptr);
463 if (pi->is_dereferenced && !pi->name_mem_tag && !ann->type_mem_tag)
465 error ("dereferenced pointers should have a name or a type tag");
471 && (pi->pt_vars == NULL || bitmap_empty_p (pi->pt_vars)))
473 error ("pointers with a memory tag, should have points-to sets or point to malloc");
477 if (pi->value_escapes_p
479 && !is_call_clobbered (pi->name_mem_tag))
481 error ("pointer escapes but its name tag is not call-clobbered");
489 debug_variable (ptr);
490 internal_error ("verify_flow_sensitive_alias_info failed");
494 DEF_VEC_ALLOC_P (bitmap,heap);
496 /* Verify that all name tags have different points to sets.
497 This algorithm takes advantage of the fact that every variable with the
498 same name tag must have the same points-to set.
499 So we check a single variable for each name tag, and verify that its
500 points-to set is different from every other points-to set for other name
503 Additionally, given a pointer P_i with name tag NMT and type tag
504 TMT, this function verified the alias set of TMT is a superset of
505 the alias set of NMT. */
508 verify_name_tags (void)
512 bitmap first, second;
513 VEC(tree,heap) *name_tag_reps = NULL;
514 VEC(bitmap,heap) *pt_vars_for_reps = NULL;
515 bitmap type_aliases = BITMAP_ALLOC (NULL);
517 /* First we compute the name tag representatives and their points-to sets. */
518 for (i = 0; i < num_ssa_names; i++)
520 struct ptr_info_def *pi;
521 tree tmt, ptr = ssa_name (i);
523 if (ptr == NULL_TREE)
526 pi = SSA_NAME_PTR_INFO (ptr);
528 if (!TREE_VISITED (ptr)
529 || !POINTER_TYPE_P (TREE_TYPE (ptr))
532 || TREE_VISITED (pi->name_mem_tag))
535 TREE_VISITED (pi->name_mem_tag) = 1;
537 if (pi->pt_vars == NULL)
540 VEC_safe_push (tree, heap, name_tag_reps, ptr);
541 VEC_safe_push (bitmap, heap, pt_vars_for_reps, pi->pt_vars);
543 /* Verify that alias set of PTR's type tag is a superset of the
544 alias set of PTR's name tag. */
545 tmt = var_ann (SSA_NAME_VAR (ptr))->type_mem_tag;
549 varray_type aliases = var_ann (tmt)->may_aliases;
550 bitmap_clear (type_aliases);
551 for (i = 0; aliases && i < VARRAY_ACTIVE_SIZE (aliases); i++)
553 tree alias = VARRAY_TREE (aliases, i);
554 bitmap_set_bit (type_aliases, DECL_UID (alias));
557 /* When grouping, we may have added PTR's type tag into the
558 alias set of PTR's name tag. To prevent a false
559 positive, pretend that TMT is in its own alias set. */
560 bitmap_set_bit (type_aliases, DECL_UID (tmt));
562 if (bitmap_equal_p (type_aliases, pi->pt_vars))
565 if (!bitmap_intersect_compl_p (type_aliases, pi->pt_vars))
567 error ("alias set of a pointer's type tag should be a superset of the corresponding name tag");
568 debug_variable (tmt);
569 debug_variable (pi->name_mem_tag);
575 /* Now compare all the representative bitmaps with all other representative
576 bitmaps, to verify that they are all different. */
577 for (i = 0; VEC_iterate (bitmap, pt_vars_for_reps, i, first); i++)
579 for (j = i + 1; VEC_iterate (bitmap, pt_vars_for_reps, j, second); j++)
581 if (bitmap_equal_p (first, second))
583 error ("two different pointers with identical points-to sets but different name tags");
584 debug_variable (VEC_index (tree, name_tag_reps, j));
590 /* Lastly, clear out the visited flags. */
591 for (i = 0; i < num_ssa_names; i++)
595 tree ptr = ssa_name (i);
596 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
597 if (!TREE_VISITED (ptr)
598 || !POINTER_TYPE_P (TREE_TYPE (ptr))
600 || !pi->name_mem_tag)
602 TREE_VISITED (pi->name_mem_tag) = 0;
606 /* We do not have to free the bitmaps or trees in the vectors, as
607 they are not owned by us. */
608 VEC_free (bitmap, heap, pt_vars_for_reps);
609 VEC_free (tree, heap, name_tag_reps);
610 BITMAP_FREE (type_aliases);
614 debug_variable (VEC_index (tree, name_tag_reps, i));
615 internal_error ("verify_name_tags failed");
619 /* Verify the consistency of aliasing information. */
622 verify_alias_info (void)
624 verify_flow_sensitive_alias_info ();
626 verify_flow_insensitive_alias_info ();
630 /* Verify common invariants in the SSA web.
631 TODO: verify the variable annotations. */
634 verify_ssa (bool check_modified_stmt)
638 basic_block *definition_block = xcalloc (num_ssa_names, sizeof (basic_block));
641 enum dom_state orig_dom_state = dom_computed[CDI_DOMINATORS];
642 bitmap names_defined_in_bb = BITMAP_ALLOC (NULL);
644 gcc_assert (!need_ssa_update_p ());
648 timevar_push (TV_TREE_SSA_VERIFY);
650 /* Keep track of SSA names present in the IL. */
651 for (i = 1; i < num_ssa_names; i++)
653 tree name = ssa_name (i);
657 TREE_VISITED (name) = 0;
659 stmt = SSA_NAME_DEF_STMT (name);
660 if (!IS_EMPTY_STMT (stmt))
662 basic_block bb = bb_for_stmt (stmt);
663 verify_def (bb, definition_block,
664 name, stmt, !is_gimple_reg (name));
670 calculate_dominance_info (CDI_DOMINATORS);
672 /* Now verify all the uses and make sure they agree with the definitions
673 found in the previous pass. */
679 block_stmt_iterator bsi;
681 /* Make sure that all edges have a clear 'aux' field. */
682 FOR_EACH_EDGE (e, ei, bb->preds)
686 error ("AUX pointer initialized for edge %d->%d", e->src->index,
692 /* Verify the arguments for every PHI node in the block. */
693 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
695 if (verify_phi_args (phi, bb, definition_block))
697 bitmap_set_bit (names_defined_in_bb,
698 SSA_NAME_VERSION (PHI_RESULT (phi)));
701 /* Now verify all the uses and vuses in every statement of the block. */
702 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
704 tree stmt = bsi_stmt (bsi);
707 if (check_modified_stmt && stmt_modified_p (stmt))
709 error ("stmt (%p) marked modified after optimization pass : ",
711 print_generic_stmt (stderr, stmt, TDF_VOPS);
715 if (TREE_CODE (stmt) == MODIFY_EXPR
716 && TREE_CODE (TREE_OPERAND (stmt, 0)) != SSA_NAME)
718 tree lhs, base_address;
720 lhs = TREE_OPERAND (stmt, 0);
721 base_address = get_base_address (lhs);
724 && SSA_VAR_P (base_address)
725 && ZERO_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF|SSA_OP_VMUSTDEF))
727 error ("statement makes a memory store, but has no "
728 "V_MAY_DEFS nor V_MUST_DEFS");
729 print_generic_stmt (stderr, stmt, TDF_VOPS);
735 if (stmt_ann (stmt)->makes_aliased_stores
736 && ZERO_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF))
738 error ("statement makes aliased stores, but has no V_MAY_DEFS");
739 print_generic_stmt (stderr, stmt, TDF_VOPS);
743 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter,
744 SSA_OP_ALL_USES | SSA_OP_ALL_KILLS)
746 op = USE_FROM_PTR (use_p);
747 if (verify_use (bb, definition_block[SSA_NAME_VERSION (op)],
748 use_p, stmt, false, !is_gimple_reg (op),
749 names_defined_in_bb))
753 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_DEFS)
754 bitmap_set_bit (names_defined_in_bb, SSA_NAME_VERSION (op));
757 bitmap_clear (names_defined_in_bb);
760 /* Finally, verify alias information. */
761 verify_alias_info ();
763 free (definition_block);
765 /* Restore the dominance information to its prior known state, so
766 that we do not perturb the compiler's subsequent behavior. */
767 if (orig_dom_state == DOM_NONE)
768 free_dominance_info (CDI_DOMINATORS);
770 dom_computed[CDI_DOMINATORS] = orig_dom_state;
772 BITMAP_FREE (names_defined_in_bb);
773 timevar_pop (TV_TREE_SSA_VERIFY);
777 internal_error ("verify_ssa failed");
780 /* Return true if the uid in both int tree maps are equal. */
783 int_tree_map_eq (const void *va, const void *vb)
785 const struct int_tree_map *a = va, *b = vb;
786 return (a->uid == b->uid);
789 /* Hash a UID in a int_tree_map. */
792 int_tree_map_hash (const void *item)
794 return ((const struct int_tree_map *)item)->uid;
798 /* Initialize global DFA and SSA structures. */
803 referenced_vars = htab_create_ggc (20, int_tree_map_hash,
804 int_tree_map_eq, NULL);
805 call_clobbered_vars = BITMAP_ALLOC (NULL);
806 addressable_vars = BITMAP_ALLOC (NULL);
809 global_var = NULL_TREE;
810 aliases_computed_p = false;
814 /* Deallocate memory associated with SSA data structures for FNDECL. */
817 delete_tree_ssa (void)
821 block_stmt_iterator bsi;
822 referenced_var_iterator rvi;
825 /* Release any ssa_names still in use. */
826 for (i = 0; i < num_ssa_names; i++)
828 tree var = ssa_name (i);
829 if (var && TREE_CODE (var) == SSA_NAME)
831 SSA_NAME_IMM_USE_NODE (var).prev = &(SSA_NAME_IMM_USE_NODE (var));
832 SSA_NAME_IMM_USE_NODE (var).next = &(SSA_NAME_IMM_USE_NODE (var));
834 release_ssa_name (var);
837 /* Remove annotations from every tree in the function. */
840 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
842 tree stmt = bsi_stmt (bsi);
843 stmt_ann_t ann = get_stmt_ann (stmt);
845 free_ssa_operands (&ann->operands);
846 ann->addresses_taken = 0;
847 mark_stmt_modified (stmt);
849 set_phi_nodes (bb, NULL);
852 /* Remove annotations from every referenced variable. */
853 FOR_EACH_REFERENCED_VAR (var, rvi)
855 ggc_free (var->common.ann);
856 var->common.ann = NULL;
858 htab_delete (referenced_vars);
859 referenced_vars = NULL;
864 global_var = NULL_TREE;
865 BITMAP_FREE (call_clobbered_vars);
866 call_clobbered_vars = NULL;
867 BITMAP_FREE (addressable_vars);
868 addressable_vars = NULL;
869 modified_noreturn_calls = NULL;
870 aliases_computed_p = false;
871 gcc_assert (!need_ssa_update_p ());
875 /* Return true if the conversion from INNER_TYPE to OUTER_TYPE is a
876 useless type conversion, otherwise return false. */
879 tree_ssa_useless_type_conversion_1 (tree outer_type, tree inner_type)
881 if (inner_type == outer_type)
884 /* Changes in machine mode are never useless conversions. */
885 if (TYPE_MODE (inner_type) != TYPE_MODE (outer_type))
888 /* If the inner and outer types are effectively the same, then
889 strip the type conversion and enter the equivalence into
891 if (lang_hooks.types_compatible_p (inner_type, outer_type))
894 /* If both types are pointers and the outer type is a (void *), then
895 the conversion is not necessary. The opposite is not true since
896 that conversion would result in a loss of information if the
897 equivalence was used. Consider an indirect function call where
898 we need to know the exact type of the function to correctly
899 implement the ABI. */
900 else if (POINTER_TYPE_P (inner_type)
901 && POINTER_TYPE_P (outer_type)
902 && TYPE_REF_CAN_ALIAS_ALL (inner_type)
903 == TYPE_REF_CAN_ALIAS_ALL (outer_type)
904 && TREE_CODE (TREE_TYPE (outer_type)) == VOID_TYPE)
907 /* Pointers/references are equivalent if their pointed to types
908 are effectively the same. This allows to strip conversions between
909 pointer types with different type qualifiers. */
910 else if (POINTER_TYPE_P (inner_type)
911 && POINTER_TYPE_P (outer_type)
912 && TYPE_REF_CAN_ALIAS_ALL (inner_type)
913 == TYPE_REF_CAN_ALIAS_ALL (outer_type)
914 && lang_hooks.types_compatible_p (TREE_TYPE (inner_type),
915 TREE_TYPE (outer_type)))
918 /* If both the inner and outer types are integral types, then the
919 conversion is not necessary if they have the same mode and
920 signedness and precision, and both or neither are boolean. Some
921 code assumes an invariant that boolean types stay boolean and do
922 not become 1-bit bit-field types. Note that types with precision
923 not using all bits of the mode (such as bit-field types in C)
924 mean that testing of precision is necessary. */
925 else if (INTEGRAL_TYPE_P (inner_type)
926 && INTEGRAL_TYPE_P (outer_type)
927 && TYPE_UNSIGNED (inner_type) == TYPE_UNSIGNED (outer_type)
928 && TYPE_PRECISION (inner_type) == TYPE_PRECISION (outer_type)
929 && simple_cst_equal (TYPE_MAX_VALUE (inner_type), TYPE_MAX_VALUE (outer_type))
930 && simple_cst_equal (TYPE_MIN_VALUE (inner_type), TYPE_MIN_VALUE (outer_type)))
932 bool first_boolean = (TREE_CODE (inner_type) == BOOLEAN_TYPE);
933 bool second_boolean = (TREE_CODE (outer_type) == BOOLEAN_TYPE);
934 if (first_boolean == second_boolean)
938 /* Recurse for complex types. */
939 else if (TREE_CODE (inner_type) == COMPLEX_TYPE
940 && TREE_CODE (outer_type) == COMPLEX_TYPE
941 && tree_ssa_useless_type_conversion_1 (TREE_TYPE (outer_type),
942 TREE_TYPE (inner_type)))
948 /* Return true if EXPR is a useless type conversion, otherwise return
952 tree_ssa_useless_type_conversion (tree expr)
954 /* If we have an assignment that merely uses a NOP_EXPR to change
955 the top of the RHS to the type of the LHS and the type conversion
956 is "safe", then strip away the type conversion so that we can
957 enter LHS = RHS into the const_and_copies table. */
958 if (TREE_CODE (expr) == NOP_EXPR || TREE_CODE (expr) == CONVERT_EXPR
959 || TREE_CODE (expr) == VIEW_CONVERT_EXPR
960 || TREE_CODE (expr) == NON_LVALUE_EXPR)
961 return tree_ssa_useless_type_conversion_1 (TREE_TYPE (expr),
962 TREE_TYPE (TREE_OPERAND (expr,
969 /* Returns true if statement STMT may read memory. */
972 stmt_references_memory_p (tree stmt)
974 stmt_ann_t ann = stmt_ann (stmt);
976 if (ann->has_volatile_ops)
979 return (!ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS));
982 /* Internal helper for walk_use_def_chains. VAR, FN and DATA are as
983 described in walk_use_def_chains.
985 VISITED is a pointer set used to mark visited SSA_NAMEs to avoid
986 infinite loops. We used to have a bitmap for this to just mark
987 SSA versions we had visited. But non-sparse bitmaps are way too
988 expensive, while sparse bitmaps may cause quadratic behavior.
990 IS_DFS is true if the caller wants to perform a depth-first search
991 when visiting PHI nodes. A DFS will visit each PHI argument and
992 call FN after each one. Otherwise, all the arguments are
993 visited first and then FN is called with each of the visited
994 arguments in a separate pass. */
997 walk_use_def_chains_1 (tree var, walk_use_def_chains_fn fn, void *data,
998 struct pointer_set_t *visited, bool is_dfs)
1002 if (pointer_set_insert (visited, var))
1005 def_stmt = SSA_NAME_DEF_STMT (var);
1007 if (TREE_CODE (def_stmt) != PHI_NODE)
1009 /* If we reached the end of the use-def chain, call FN. */
1010 return fn (var, def_stmt, data);
1016 /* When doing a breadth-first search, call FN before following the
1017 use-def links for each argument. */
1019 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
1020 if (fn (PHI_ARG_DEF (def_stmt, i), def_stmt, data))
1023 /* Follow use-def links out of each PHI argument. */
1024 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
1026 tree arg = PHI_ARG_DEF (def_stmt, i);
1027 if (TREE_CODE (arg) == SSA_NAME
1028 && walk_use_def_chains_1 (arg, fn, data, visited, is_dfs))
1032 /* When doing a depth-first search, call FN after following the
1033 use-def links for each argument. */
1035 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
1036 if (fn (PHI_ARG_DEF (def_stmt, i), def_stmt, data))
1045 /* Walk use-def chains starting at the SSA variable VAR. Call
1046 function FN at each reaching definition found. FN takes three
1047 arguments: VAR, its defining statement (DEF_STMT) and a generic
1048 pointer to whatever state information that FN may want to maintain
1049 (DATA). FN is able to stop the walk by returning true, otherwise
1050 in order to continue the walk, FN should return false.
1052 Note, that if DEF_STMT is a PHI node, the semantics are slightly
1053 different. The first argument to FN is no longer the original
1054 variable VAR, but the PHI argument currently being examined. If FN
1055 wants to get at VAR, it should call PHI_RESULT (PHI).
1057 If IS_DFS is true, this function will:
1059 1- walk the use-def chains for all the PHI arguments, and,
1060 2- call (*FN) (ARG, PHI, DATA) on all the PHI arguments.
1062 If IS_DFS is false, the two steps above are done in reverse order
1063 (i.e., a breadth-first search). */
1067 walk_use_def_chains (tree var, walk_use_def_chains_fn fn, void *data,
1072 gcc_assert (TREE_CODE (var) == SSA_NAME);
1074 def_stmt = SSA_NAME_DEF_STMT (var);
1076 /* We only need to recurse if the reaching definition comes from a PHI
1078 if (TREE_CODE (def_stmt) != PHI_NODE)
1079 (*fn) (var, def_stmt, data);
1082 struct pointer_set_t *visited = pointer_set_create ();
1083 walk_use_def_chains_1 (var, fn, data, visited, is_dfs);
1084 pointer_set_destroy (visited);
1089 /* Emit warnings for uninitialized variables. This is done in two passes.
1091 The first pass notices real uses of SSA names with default definitions.
1092 Such uses are unconditionally uninitialized, and we can be certain that
1093 such a use is a mistake. This pass is run before most optimizations,
1094 so that we catch as many as we can.
1096 The second pass follows PHI nodes to find uses that are potentially
1097 uninitialized. In this case we can't necessarily prove that the use
1098 is really uninitialized. This pass is run after most optimizations,
1099 so that we thread as many jumps and possible, and delete as much dead
1100 code as possible, in order to reduce false positives. We also look
1101 again for plain uninitialized variables, since optimization may have
1102 changed conditionally uninitialized to unconditionally uninitialized. */
1104 /* Emit a warning for T, an SSA_NAME, being uninitialized. The exact
1105 warning text is in MSGID and LOCUS may contain a location or be null. */
1108 warn_uninit (tree t, const char *gmsgid, void *data)
1110 tree var = SSA_NAME_VAR (t);
1111 tree def = SSA_NAME_DEF_STMT (t);
1112 tree context = (tree) data;
1115 /* Default uses (indicated by an empty definition statement),
1116 are uninitialized. */
1117 if (!IS_EMPTY_STMT (def))
1120 /* Except for PARMs of course, which are always initialized. */
1121 if (TREE_CODE (var) == PARM_DECL)
1124 /* Hard register variables get their initial value from the ether. */
1125 if (TREE_CODE (var) == VAR_DECL && DECL_HARD_REGISTER (var))
1128 /* TREE_NO_WARNING either means we already warned, or the front end
1129 wishes to suppress the warning. */
1130 if (TREE_NO_WARNING (var))
1133 locus = (context != NULL && EXPR_HAS_LOCATION (context)
1134 ? EXPR_LOCUS (context)
1135 : &DECL_SOURCE_LOCATION (var));
1136 warning (0, gmsgid, locus, var);
1137 TREE_NO_WARNING (var) = 1;
1140 /* Called via walk_tree, look for SSA_NAMEs that have empty definitions
1141 and warn about them. */
1144 warn_uninitialized_var (tree *tp, int *walk_subtrees, void *data)
1148 /* We only do data flow with SSA_NAMEs, so that's all we can warn about. */
1149 if (TREE_CODE (t) == SSA_NAME)
1151 warn_uninit (t, "%H%qD is used uninitialized in this function", data);
1154 else if (IS_TYPE_OR_DECL_P (t))
1160 /* Look for inputs to PHI that are SSA_NAMEs that have empty definitions
1161 and warn about them. */
1164 warn_uninitialized_phi (tree phi)
1166 int i, n = PHI_NUM_ARGS (phi);
1168 /* Don't look at memory tags. */
1169 if (!is_gimple_reg (PHI_RESULT (phi)))
1172 for (i = 0; i < n; ++i)
1174 tree op = PHI_ARG_DEF (phi, i);
1175 if (TREE_CODE (op) == SSA_NAME)
1176 warn_uninit (op, "%H%qD may be used uninitialized in this function",
1182 execute_early_warn_uninitialized (void)
1184 block_stmt_iterator bsi;
1188 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1190 tree context = bsi_stmt (bsi);
1191 walk_tree (bsi_stmt_ptr (bsi), warn_uninitialized_var,
1197 execute_late_warn_uninitialized (void)
1202 /* Re-do the plain uninitialized variable check, as optimization may have
1203 straightened control flow. Do this first so that we don't accidentally
1204 get a "may be" warning when we'd have seen an "is" warning later. */
1205 execute_early_warn_uninitialized ();
1208 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
1209 warn_uninitialized_phi (phi);
1213 gate_warn_uninitialized (void)
1215 return warn_uninitialized != 0;
1218 struct tree_opt_pass pass_early_warn_uninitialized =
1221 gate_warn_uninitialized, /* gate */
1222 execute_early_warn_uninitialized, /* execute */
1225 0, /* static_pass_number */
1227 PROP_ssa, /* properties_required */
1228 0, /* properties_provided */
1229 0, /* properties_destroyed */
1230 0, /* todo_flags_start */
1231 0, /* todo_flags_finish */
1235 struct tree_opt_pass pass_late_warn_uninitialized =
1238 gate_warn_uninitialized, /* gate */
1239 execute_late_warn_uninitialized, /* execute */
1242 0, /* static_pass_number */
1244 PROP_ssa, /* properties_required */
1245 0, /* properties_provided */
1246 0, /* properties_destroyed */
1247 0, /* todo_flags_start */
1248 0, /* todo_flags_finish */