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 && default_def (SSA_NAME_VAR (ssa_name)) == 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)
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");
470 && (pi->pt_vars == NULL || bitmap_empty_p (pi->pt_vars)))
472 error ("pointers with a memory tag, should have points-to sets");
476 if (pi->value_escapes_p
478 && !is_call_clobbered (pi->name_mem_tag))
480 error ("pointer escapes but its name tag is not call-clobbered");
488 debug_variable (ptr);
489 internal_error ("verify_flow_sensitive_alias_info failed");
493 DEF_VEC_ALLOC_P (bitmap,heap);
495 /* Verify that all name tags have different points to sets.
496 This algorithm takes advantage of the fact that every variable with the
497 same name tag must have the same points-to set.
498 So we check a single variable for each name tag, and verify that its
499 points-to set is different from every other points-to set for other name
502 Additionally, given a pointer P_i with name tag NMT and type tag
503 TMT, this function verified the alias set of TMT is a superset of
504 the alias set of NMT. */
507 verify_name_tags (void)
511 bitmap first, second;
512 VEC(tree,heap) *name_tag_reps = NULL;
513 VEC(bitmap,heap) *pt_vars_for_reps = NULL;
514 bitmap type_aliases = BITMAP_ALLOC (NULL);
516 /* First we compute the name tag representatives and their points-to sets. */
517 for (i = 0; i < num_ssa_names; i++)
519 struct ptr_info_def *pi;
520 tree tmt, ptr = ssa_name (i);
522 if (ptr == NULL_TREE)
525 pi = SSA_NAME_PTR_INFO (ptr);
527 if (!TREE_VISITED (ptr)
528 || !POINTER_TYPE_P (TREE_TYPE (ptr))
531 || TREE_VISITED (pi->name_mem_tag))
534 TREE_VISITED (pi->name_mem_tag) = 1;
536 if (pi->pt_vars == NULL)
539 VEC_safe_push (tree, heap, name_tag_reps, ptr);
540 VEC_safe_push (bitmap, heap, pt_vars_for_reps, pi->pt_vars);
542 /* Verify that alias set of PTR's type tag is a superset of the
543 alias set of PTR's name tag. */
544 tmt = var_ann (SSA_NAME_VAR (ptr))->type_mem_tag;
548 varray_type aliases = var_ann (tmt)->may_aliases;
549 bitmap_clear (type_aliases);
550 for (i = 0; aliases && i < VARRAY_ACTIVE_SIZE (aliases); i++)
552 tree alias = VARRAY_TREE (aliases, i);
553 bitmap_set_bit (type_aliases, DECL_UID (alias));
556 /* When grouping, we may have added PTR's type tag into the
557 alias set of PTR's name tag. To prevent a false
558 positive, pretend that TMT is in its own alias set. */
559 bitmap_set_bit (type_aliases, DECL_UID (tmt));
561 if (bitmap_equal_p (type_aliases, pi->pt_vars))
564 if (!bitmap_intersect_compl_p (type_aliases, pi->pt_vars))
566 error ("alias set of a pointer's type tag should be a superset of the corresponding name tag");
567 debug_variable (tmt);
568 debug_variable (pi->name_mem_tag);
574 /* Now compare all the representative bitmaps with all other representative
575 bitmaps, to verify that they are all different. */
576 for (i = 0; VEC_iterate (bitmap, pt_vars_for_reps, i, first); i++)
578 for (j = i + 1; VEC_iterate (bitmap, pt_vars_for_reps, j, second); j++)
580 if (bitmap_equal_p (first, second))
582 error ("two different pointers with identical points-to sets but different name tags");
583 debug_variable (VEC_index (tree, name_tag_reps, j));
589 /* Lastly, clear out the visited flags. */
590 for (i = 0; i < num_ssa_names; i++)
594 tree ptr = ssa_name (i);
595 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
596 if (!TREE_VISITED (ptr)
597 || !POINTER_TYPE_P (TREE_TYPE (ptr))
599 || !pi->name_mem_tag)
601 TREE_VISITED (pi->name_mem_tag) = 0;
605 /* We do not have to free the bitmaps or trees in the vectors, as
606 they are not owned by us. */
607 VEC_free (bitmap, heap, pt_vars_for_reps);
608 VEC_free (tree, heap, name_tag_reps);
609 BITMAP_FREE (type_aliases);
613 debug_variable (VEC_index (tree, name_tag_reps, i));
614 internal_error ("verify_name_tags failed");
618 /* Verify the consistency of aliasing information. */
621 verify_alias_info (void)
623 verify_flow_sensitive_alias_info ();
625 verify_flow_insensitive_alias_info ();
629 /* Verify common invariants in the SSA web.
630 TODO: verify the variable annotations. */
633 verify_ssa (bool check_modified_stmt)
637 basic_block *definition_block = xcalloc (num_ssa_names, sizeof (basic_block));
640 enum dom_state orig_dom_state = dom_computed[CDI_DOMINATORS];
641 bitmap names_defined_in_bb = BITMAP_ALLOC (NULL);
643 gcc_assert (!need_ssa_update_p ());
647 timevar_push (TV_TREE_SSA_VERIFY);
649 /* Keep track of SSA names present in the IL. */
650 for (i = 1; i < num_ssa_names; i++)
652 tree name = ssa_name (i);
656 TREE_VISITED (name) = 0;
658 stmt = SSA_NAME_DEF_STMT (name);
659 if (!IS_EMPTY_STMT (stmt))
661 basic_block bb = bb_for_stmt (stmt);
662 verify_def (bb, definition_block,
663 name, stmt, !is_gimple_reg (name));
669 calculate_dominance_info (CDI_DOMINATORS);
671 /* Now verify all the uses and make sure they agree with the definitions
672 found in the previous pass. */
678 block_stmt_iterator bsi;
680 /* Make sure that all edges have a clear 'aux' field. */
681 FOR_EACH_EDGE (e, ei, bb->preds)
685 error ("AUX pointer initialized for edge %d->%d", e->src->index,
691 /* Verify the arguments for every PHI node in the block. */
692 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
694 if (verify_phi_args (phi, bb, definition_block))
696 bitmap_set_bit (names_defined_in_bb,
697 SSA_NAME_VERSION (PHI_RESULT (phi)));
700 /* Now verify all the uses and vuses in every statement of the block. */
701 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
703 tree stmt = bsi_stmt (bsi);
706 if (check_modified_stmt && stmt_modified_p (stmt))
708 error ("stmt (%p) marked modified after optimization pass : ",
710 print_generic_stmt (stderr, stmt, TDF_VOPS);
714 if (TREE_CODE (stmt) == MODIFY_EXPR
715 && TREE_CODE (TREE_OPERAND (stmt, 0)) != SSA_NAME)
717 tree lhs, base_address;
719 lhs = TREE_OPERAND (stmt, 0);
720 base_address = get_base_address (lhs);
723 && SSA_VAR_P (base_address)
724 && ZERO_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF|SSA_OP_VMUSTDEF))
726 error ("statement makes a memory store, but has no "
727 "V_MAY_DEFS nor V_MUST_DEFS");
728 print_generic_stmt (stderr, stmt, TDF_VOPS);
734 if (stmt_ann (stmt)->makes_aliased_stores
735 && ZERO_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF))
737 error ("statement makes aliased stores, but has no V_MAY_DEFS");
738 print_generic_stmt (stderr, stmt, TDF_VOPS);
742 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter,
743 SSA_OP_ALL_USES | SSA_OP_ALL_KILLS)
745 op = USE_FROM_PTR (use_p);
746 if (verify_use (bb, definition_block[SSA_NAME_VERSION (op)],
747 use_p, stmt, false, !is_gimple_reg (op),
748 names_defined_in_bb))
752 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_DEFS)
753 bitmap_set_bit (names_defined_in_bb, SSA_NAME_VERSION (op));
756 bitmap_clear (names_defined_in_bb);
759 /* Finally, verify alias information. */
760 verify_alias_info ();
762 free (definition_block);
764 /* Restore the dominance information to its prior known state, so
765 that we do not perturb the compiler's subsequent behavior. */
766 if (orig_dom_state == DOM_NONE)
767 free_dominance_info (CDI_DOMINATORS);
769 dom_computed[CDI_DOMINATORS] = orig_dom_state;
771 BITMAP_FREE (names_defined_in_bb);
772 timevar_pop (TV_TREE_SSA_VERIFY);
776 internal_error ("verify_ssa failed");
779 /* Return true if the uid in both int tree maps are equal. */
782 int_tree_map_eq (const void *va, const void *vb)
784 const struct int_tree_map *a = va, *b = vb;
785 return (a->uid == b->uid);
788 /* Hash a UID in a int_tree_map. */
791 int_tree_map_hash (const void *item)
793 return ((const struct int_tree_map *)item)->uid;
797 /* Initialize global DFA and SSA structures. */
802 referenced_vars = htab_create_ggc (20, int_tree_map_hash,
803 int_tree_map_eq, NULL);
804 default_defs = htab_create_ggc (20, int_tree_map_hash, int_tree_map_eq, NULL);
805 call_clobbered_vars = BITMAP_ALLOC (NULL);
806 addressable_vars = BITMAP_ALLOC (NULL);
807 init_alias_heapvars ();
810 global_var = NULL_TREE;
811 aliases_computed_p = false;
815 /* Deallocate memory associated with SSA data structures for FNDECL. */
818 delete_tree_ssa (void)
822 block_stmt_iterator bsi;
823 referenced_var_iterator rvi;
826 /* Release any ssa_names still in use. */
827 for (i = 0; i < num_ssa_names; i++)
829 tree var = ssa_name (i);
830 if (var && TREE_CODE (var) == SSA_NAME)
832 SSA_NAME_IMM_USE_NODE (var).prev = &(SSA_NAME_IMM_USE_NODE (var));
833 SSA_NAME_IMM_USE_NODE (var).next = &(SSA_NAME_IMM_USE_NODE (var));
835 release_ssa_name (var);
838 /* Remove annotations from every tree in the function. */
841 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
843 tree stmt = bsi_stmt (bsi);
844 stmt_ann_t ann = get_stmt_ann (stmt);
846 free_ssa_operands (&ann->operands);
847 ann->addresses_taken = 0;
848 mark_stmt_modified (stmt);
850 set_phi_nodes (bb, NULL);
853 /* Remove annotations from every referenced variable. */
854 FOR_EACH_REFERENCED_VAR (var, rvi)
856 ggc_free (var->common.ann);
857 var->common.ann = NULL;
859 htab_delete (referenced_vars);
860 referenced_vars = NULL;
865 global_var = NULL_TREE;
867 htab_delete (default_defs);
868 BITMAP_FREE (call_clobbered_vars);
869 call_clobbered_vars = NULL;
870 BITMAP_FREE (addressable_vars);
871 addressable_vars = NULL;
872 modified_noreturn_calls = NULL;
873 aliases_computed_p = false;
874 delete_alias_heapvars ();
875 gcc_assert (!need_ssa_update_p ());
879 /* Return true if the conversion from INNER_TYPE to OUTER_TYPE is a
880 useless type conversion, otherwise return false. */
883 tree_ssa_useless_type_conversion_1 (tree outer_type, tree inner_type)
885 if (inner_type == outer_type)
888 /* Changes in machine mode are never useless conversions. */
889 if (TYPE_MODE (inner_type) != TYPE_MODE (outer_type))
892 /* If the inner and outer types are effectively the same, then
893 strip the type conversion and enter the equivalence into
895 if (lang_hooks.types_compatible_p (inner_type, outer_type))
898 /* If both types are pointers and the outer type is a (void *), then
899 the conversion is not necessary. The opposite is not true since
900 that conversion would result in a loss of information if the
901 equivalence was used. Consider an indirect function call where
902 we need to know the exact type of the function to correctly
903 implement the ABI. */
904 else if (POINTER_TYPE_P (inner_type)
905 && POINTER_TYPE_P (outer_type)
906 && TYPE_REF_CAN_ALIAS_ALL (inner_type)
907 == TYPE_REF_CAN_ALIAS_ALL (outer_type)
908 && TREE_CODE (TREE_TYPE (outer_type)) == VOID_TYPE)
911 /* Don't lose casts between pointers to volatile and non-volatile
912 qualified types. Doing so would result in changing the semantics
913 of later accesses. */
914 else if (POINTER_TYPE_P (inner_type)
915 && POINTER_TYPE_P (outer_type)
916 && TYPE_VOLATILE (TREE_TYPE (outer_type))
917 != TYPE_VOLATILE (TREE_TYPE (inner_type)))
920 /* Pointers/references are equivalent if their pointed to types
921 are effectively the same. This allows to strip conversions between
922 pointer types with different type qualifiers. */
923 else if (POINTER_TYPE_P (inner_type)
924 && POINTER_TYPE_P (outer_type)
925 && TYPE_REF_CAN_ALIAS_ALL (inner_type)
926 == TYPE_REF_CAN_ALIAS_ALL (outer_type)
927 && lang_hooks.types_compatible_p (TREE_TYPE (inner_type),
928 TREE_TYPE (outer_type)))
931 /* If both the inner and outer types are integral types, then the
932 conversion is not necessary if they have the same mode and
933 signedness and precision, and both or neither are boolean. Some
934 code assumes an invariant that boolean types stay boolean and do
935 not become 1-bit bit-field types. Note that types with precision
936 not using all bits of the mode (such as bit-field types in C)
937 mean that testing of precision is necessary. */
938 else if (INTEGRAL_TYPE_P (inner_type)
939 && INTEGRAL_TYPE_P (outer_type)
940 && TYPE_UNSIGNED (inner_type) == TYPE_UNSIGNED (outer_type)
941 && TYPE_PRECISION (inner_type) == TYPE_PRECISION (outer_type)
942 && simple_cst_equal (TYPE_MAX_VALUE (inner_type), TYPE_MAX_VALUE (outer_type))
943 && simple_cst_equal (TYPE_MIN_VALUE (inner_type), TYPE_MIN_VALUE (outer_type)))
945 bool first_boolean = (TREE_CODE (inner_type) == BOOLEAN_TYPE);
946 bool second_boolean = (TREE_CODE (outer_type) == BOOLEAN_TYPE);
947 if (first_boolean == second_boolean)
951 /* Recurse for complex types. */
952 else if (TREE_CODE (inner_type) == COMPLEX_TYPE
953 && TREE_CODE (outer_type) == COMPLEX_TYPE
954 && tree_ssa_useless_type_conversion_1 (TREE_TYPE (outer_type),
955 TREE_TYPE (inner_type)))
961 /* Return true if EXPR is a useless type conversion, otherwise return
965 tree_ssa_useless_type_conversion (tree expr)
967 /* If we have an assignment that merely uses a NOP_EXPR to change
968 the top of the RHS to the type of the LHS and the type conversion
969 is "safe", then strip away the type conversion so that we can
970 enter LHS = RHS into the const_and_copies table. */
971 if (TREE_CODE (expr) == NOP_EXPR || TREE_CODE (expr) == CONVERT_EXPR
972 || TREE_CODE (expr) == VIEW_CONVERT_EXPR
973 || TREE_CODE (expr) == NON_LVALUE_EXPR)
974 return tree_ssa_useless_type_conversion_1 (TREE_TYPE (expr),
975 TREE_TYPE (TREE_OPERAND (expr,
982 /* Returns true if statement STMT may read memory. */
985 stmt_references_memory_p (tree stmt)
987 stmt_ann_t ann = stmt_ann (stmt);
989 if (ann->has_volatile_ops)
992 return (!ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS));
995 /* Internal helper for walk_use_def_chains. VAR, FN and DATA are as
996 described in walk_use_def_chains.
998 VISITED is a pointer set used to mark visited SSA_NAMEs to avoid
999 infinite loops. We used to have a bitmap for this to just mark
1000 SSA versions we had visited. But non-sparse bitmaps are way too
1001 expensive, while sparse bitmaps may cause quadratic behavior.
1003 IS_DFS is true if the caller wants to perform a depth-first search
1004 when visiting PHI nodes. A DFS will visit each PHI argument and
1005 call FN after each one. Otherwise, all the arguments are
1006 visited first and then FN is called with each of the visited
1007 arguments in a separate pass. */
1010 walk_use_def_chains_1 (tree var, walk_use_def_chains_fn fn, void *data,
1011 struct pointer_set_t *visited, bool is_dfs)
1015 if (pointer_set_insert (visited, var))
1018 def_stmt = SSA_NAME_DEF_STMT (var);
1020 if (TREE_CODE (def_stmt) != PHI_NODE)
1022 /* If we reached the end of the use-def chain, call FN. */
1023 return fn (var, def_stmt, data);
1029 /* When doing a breadth-first search, call FN before following the
1030 use-def links for each argument. */
1032 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
1033 if (fn (PHI_ARG_DEF (def_stmt, i), def_stmt, data))
1036 /* Follow use-def links out of each PHI argument. */
1037 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
1039 tree arg = PHI_ARG_DEF (def_stmt, i);
1040 if (TREE_CODE (arg) == SSA_NAME
1041 && walk_use_def_chains_1 (arg, fn, data, visited, is_dfs))
1045 /* When doing a depth-first search, call FN after following the
1046 use-def links for each argument. */
1048 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
1049 if (fn (PHI_ARG_DEF (def_stmt, i), def_stmt, data))
1058 /* Walk use-def chains starting at the SSA variable VAR. Call
1059 function FN at each reaching definition found. FN takes three
1060 arguments: VAR, its defining statement (DEF_STMT) and a generic
1061 pointer to whatever state information that FN may want to maintain
1062 (DATA). FN is able to stop the walk by returning true, otherwise
1063 in order to continue the walk, FN should return false.
1065 Note, that if DEF_STMT is a PHI node, the semantics are slightly
1066 different. The first argument to FN is no longer the original
1067 variable VAR, but the PHI argument currently being examined. If FN
1068 wants to get at VAR, it should call PHI_RESULT (PHI).
1070 If IS_DFS is true, this function will:
1072 1- walk the use-def chains for all the PHI arguments, and,
1073 2- call (*FN) (ARG, PHI, DATA) on all the PHI arguments.
1075 If IS_DFS is false, the two steps above are done in reverse order
1076 (i.e., a breadth-first search). */
1080 walk_use_def_chains (tree var, walk_use_def_chains_fn fn, void *data,
1085 gcc_assert (TREE_CODE (var) == SSA_NAME);
1087 def_stmt = SSA_NAME_DEF_STMT (var);
1089 /* We only need to recurse if the reaching definition comes from a PHI
1091 if (TREE_CODE (def_stmt) != PHI_NODE)
1092 (*fn) (var, def_stmt, data);
1095 struct pointer_set_t *visited = pointer_set_create ();
1096 walk_use_def_chains_1 (var, fn, data, visited, is_dfs);
1097 pointer_set_destroy (visited);
1102 /* Emit warnings for uninitialized variables. This is done in two passes.
1104 The first pass notices real uses of SSA names with default definitions.
1105 Such uses are unconditionally uninitialized, and we can be certain that
1106 such a use is a mistake. This pass is run before most optimizations,
1107 so that we catch as many as we can.
1109 The second pass follows PHI nodes to find uses that are potentially
1110 uninitialized. In this case we can't necessarily prove that the use
1111 is really uninitialized. This pass is run after most optimizations,
1112 so that we thread as many jumps and possible, and delete as much dead
1113 code as possible, in order to reduce false positives. We also look
1114 again for plain uninitialized variables, since optimization may have
1115 changed conditionally uninitialized to unconditionally uninitialized. */
1117 /* Emit a warning for T, an SSA_NAME, being uninitialized. The exact
1118 warning text is in MSGID and LOCUS may contain a location or be null. */
1121 warn_uninit (tree t, const char *gmsgid, void *data)
1123 tree var = SSA_NAME_VAR (t);
1124 tree def = SSA_NAME_DEF_STMT (t);
1125 tree context = (tree) data;
1128 /* Default uses (indicated by an empty definition statement),
1129 are uninitialized. */
1130 if (!IS_EMPTY_STMT (def))
1133 /* Except for PARMs of course, which are always initialized. */
1134 if (TREE_CODE (var) == PARM_DECL)
1137 /* Hard register variables get their initial value from the ether. */
1138 if (TREE_CODE (var) == VAR_DECL && DECL_HARD_REGISTER (var))
1141 /* TREE_NO_WARNING either means we already warned, or the front end
1142 wishes to suppress the warning. */
1143 if (TREE_NO_WARNING (var))
1146 locus = (context != NULL && EXPR_HAS_LOCATION (context)
1147 ? EXPR_LOCUS (context)
1148 : &DECL_SOURCE_LOCATION (var));
1149 warning (0, gmsgid, locus, var);
1150 TREE_NO_WARNING (var) = 1;
1153 /* Called via walk_tree, look for SSA_NAMEs that have empty definitions
1154 and warn about them. */
1157 warn_uninitialized_var (tree *tp, int *walk_subtrees, void *data)
1161 switch (TREE_CODE (t))
1164 /* We only do data flow with SSA_NAMEs, so that's all we
1166 warn_uninit (t, "%H%qD is used uninitialized in this function", data);
1172 /* The total store transformation performed during gimplification
1173 creates uninitialized variable uses. If all is well, these will
1174 be optimized away, so don't warn now. */
1175 if (TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME)
1180 if (IS_TYPE_OR_DECL_P (t))
1188 /* Look for inputs to PHI that are SSA_NAMEs that have empty definitions
1189 and warn about them. */
1192 warn_uninitialized_phi (tree phi)
1194 int i, n = PHI_NUM_ARGS (phi);
1196 /* Don't look at memory tags. */
1197 if (!is_gimple_reg (PHI_RESULT (phi)))
1200 for (i = 0; i < n; ++i)
1202 tree op = PHI_ARG_DEF (phi, i);
1203 if (TREE_CODE (op) == SSA_NAME)
1204 warn_uninit (op, "%H%qD may be used uninitialized in this function",
1210 execute_early_warn_uninitialized (void)
1212 block_stmt_iterator bsi;
1216 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1218 tree context = bsi_stmt (bsi);
1219 walk_tree (bsi_stmt_ptr (bsi), warn_uninitialized_var,
1225 execute_late_warn_uninitialized (void)
1230 /* Re-do the plain uninitialized variable check, as optimization may have
1231 straightened control flow. Do this first so that we don't accidentally
1232 get a "may be" warning when we'd have seen an "is" warning later. */
1233 execute_early_warn_uninitialized ();
1236 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
1237 warn_uninitialized_phi (phi);
1241 gate_warn_uninitialized (void)
1243 return warn_uninitialized != 0;
1246 struct tree_opt_pass pass_early_warn_uninitialized =
1249 gate_warn_uninitialized, /* gate */
1250 execute_early_warn_uninitialized, /* execute */
1253 0, /* static_pass_number */
1255 PROP_ssa, /* properties_required */
1256 0, /* properties_provided */
1257 0, /* properties_destroyed */
1258 0, /* todo_flags_start */
1259 0, /* todo_flags_finish */
1263 struct tree_opt_pass pass_late_warn_uninitialized =
1266 gate_warn_uninitialized, /* gate */
1267 execute_late_warn_uninitialized, /* execute */
1270 0, /* static_pass_number */
1272 PROP_ssa, /* properties_required */
1273 0, /* properties_provided */
1274 0, /* properties_destroyed */
1275 0, /* todo_flags_start */
1276 0, /* todo_flags_finish */