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 PENDING_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");
146 if (SSA_NAME_IS_DEFAULT_DEF (ssa_name)
147 && !IS_EMPTY_STMT (SSA_NAME_DEF_STMT (ssa_name)))
149 error ("found a default name with a non-empty defining statement");
157 /* Return true if the definition of SSA_NAME at block BB is malformed.
159 STMT is the statement where SSA_NAME is created.
161 DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME
162 version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set,
163 it means that the block in that array slot contains the
164 definition of SSA_NAME.
166 IS_VIRTUAL is true if SSA_NAME is created by a VDEF. */
169 verify_def (basic_block bb, basic_block *definition_block, tree ssa_name,
170 tree stmt, bool is_virtual)
172 if (verify_ssa_name (ssa_name, is_virtual))
175 if (definition_block[SSA_NAME_VERSION (ssa_name)])
177 error ("SSA_NAME created in two different blocks %i and %i",
178 definition_block[SSA_NAME_VERSION (ssa_name)]->index, bb->index);
182 definition_block[SSA_NAME_VERSION (ssa_name)] = bb;
184 if (SSA_NAME_DEF_STMT (ssa_name) != stmt)
186 error ("SSA_NAME_DEF_STMT is wrong");
187 fprintf (stderr, "Expected definition statement:\n");
188 print_generic_stmt (stderr, SSA_NAME_DEF_STMT (ssa_name), TDF_VOPS);
189 fprintf (stderr, "\nActual definition statement:\n");
190 print_generic_stmt (stderr, stmt, TDF_VOPS);
197 fprintf (stderr, "while verifying SSA_NAME ");
198 print_generic_expr (stderr, ssa_name, 0);
199 fprintf (stderr, " in statement\n");
200 print_generic_stmt (stderr, stmt, TDF_VOPS);
206 /* Return true if the use of SSA_NAME at statement STMT in block BB is
209 DEF_BB is the block where SSA_NAME was found to be created.
211 IDOM contains immediate dominator information for the flowgraph.
213 CHECK_ABNORMAL is true if the caller wants to check whether this use
214 is flowing through an abnormal edge (only used when checking PHI
217 If NAMES_DEFINED_IN_BB is not NULL, it contains a bitmap of ssa names
218 that are defined before STMT in basic block BB. */
221 verify_use (basic_block bb, basic_block def_bb, use_operand_p use_p,
222 tree stmt, bool check_abnormal, bitmap names_defined_in_bb)
225 tree ssa_name = USE_FROM_PTR (use_p);
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 && SSA_NAME_IS_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
300 version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set,
301 it means that the block in that array slot contains the
302 definition of SSA_NAME. */
305 verify_phi_args (tree phi, basic_block bb, basic_block *definition_block)
309 unsigned i, phi_num_args = PHI_NUM_ARGS (phi);
311 if (EDGE_COUNT (bb->preds) != phi_num_args)
313 error ("incoming edge count does not match number of PHI arguments");
318 for (i = 0; i < phi_num_args; i++)
320 use_operand_p op_p = PHI_ARG_DEF_PTR (phi, i);
321 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)
342 err = verify_ssa_name (op, !is_gimple_reg (PHI_RESULT (phi)));
343 err |= verify_use (e->src, definition_block[SSA_NAME_VERSION (op)],
344 op_p, phi, e->flags & EDGE_ABNORMAL, NULL);
349 error ("wrong edge %d->%d for PHI argument",
350 e->src->index, e->dest->index);
356 fprintf (stderr, "PHI argument\n");
357 print_generic_stmt (stderr, op, TDF_VOPS);
365 fprintf (stderr, "for PHI node\n");
366 print_generic_stmt (stderr, phi, TDF_VOPS|TDF_MEMSYMS);
375 verify_flow_insensitive_alias_info (void)
378 bitmap visited = BITMAP_ALLOC (NULL);
379 referenced_var_iterator rvi;
381 FOR_EACH_REFERENCED_VAR (var, rvi)
385 VEC(tree,gc) *may_aliases;
389 may_aliases = ann->may_aliases;
391 for (j = 0; VEC_iterate (tree, may_aliases, j, alias); j++)
393 bitmap_set_bit (visited, DECL_UID (alias));
395 if (TREE_CODE (alias) != MEMORY_PARTITION_TAG
396 && !may_be_aliased (alias))
398 error ("non-addressable variable inside an alias set");
399 debug_variable (alias);
405 FOR_EACH_REFERENCED_VAR (var, rvi)
412 && memory_partition (var) == NULL_TREE
413 && !bitmap_bit_p (visited, DECL_UID (var)))
415 error ("addressable variable that is aliased but is not in any "
421 BITMAP_FREE (visited);
425 debug_variable (var);
426 internal_error ("verify_flow_insensitive_alias_info failed");
431 verify_flow_sensitive_alias_info (void)
436 for (i = 1; i < num_ssa_names; i++)
440 struct ptr_info_def *pi;
447 /* We only care for pointers that are actually referenced in the
449 if (!POINTER_TYPE_P (TREE_TYPE (ptr)) || !TREE_VISITED (ptr))
452 /* RESULT_DECL is special. If it's a GIMPLE register, then it
453 is only written-to only once in the return statement.
454 Otherwise, aggregate RESULT_DECLs may be written-to more than
455 once in virtual operands. */
456 var = SSA_NAME_VAR (ptr);
457 if (TREE_CODE (var) == RESULT_DECL
458 && is_gimple_reg (ptr))
461 pi = SSA_NAME_PTR_INFO (ptr);
466 if (pi->is_dereferenced && !pi->name_mem_tag && !ann->symbol_mem_tag)
468 error ("dereferenced pointers should have a name or a symbol tag");
473 && (pi->pt_vars == NULL || bitmap_empty_p (pi->pt_vars)))
475 error ("pointers with a memory tag, should have points-to sets");
479 if (pi->value_escapes_p && pi->name_mem_tag)
481 tree t = memory_partition (pi->name_mem_tag);
483 t = pi->name_mem_tag;
485 if (!is_call_clobbered (t))
487 error ("pointer escapes but its name tag is not call-clobbered");
496 debug_variable (ptr);
497 internal_error ("verify_flow_sensitive_alias_info failed");
501 /* Verify the consistency of call clobbering information. */
504 verify_call_clobbering (void)
509 referenced_var_iterator rvi;
511 /* At all times, the result of the DECL_CALL_CLOBBERED flag should
512 match the result of the call_clobbered_vars bitmap. Verify both
513 that everything in call_clobbered_vars is marked
514 DECL_CALL_CLOBBERED, and that everything marked
515 DECL_CALL_CLOBBERED is in call_clobbered_vars. */
516 EXECUTE_IF_SET_IN_BITMAP (gimple_call_clobbered_vars (cfun), 0, i, bi)
518 var = referenced_var (i);
520 if (memory_partition (var))
521 var = memory_partition (var);
523 if (!MTAG_P (var) && !DECL_CALL_CLOBBERED (var))
525 error ("variable in call_clobbered_vars but not marked "
526 "DECL_CALL_CLOBBERED");
527 debug_variable (var);
532 FOR_EACH_REFERENCED_VAR (var, rvi)
534 if (is_gimple_reg (var))
537 if (memory_partition (var))
538 var = memory_partition (var);
541 && DECL_CALL_CLOBBERED (var)
542 && !bitmap_bit_p (gimple_call_clobbered_vars (cfun), DECL_UID (var)))
544 error ("variable marked DECL_CALL_CLOBBERED but not in "
545 "call_clobbered_vars bitmap.");
546 debug_variable (var);
554 internal_error ("verify_call_clobbering failed");
557 /* Verify the consistency of aliasing information. */
560 verify_alias_info (void)
562 verify_flow_sensitive_alias_info ();
563 verify_call_clobbering ();
564 verify_flow_insensitive_alias_info ();
568 /* Verify common invariants in the SSA web.
569 TODO: verify the variable annotations. */
572 verify_ssa (bool check_modified_stmt)
576 basic_block *definition_block = XCNEWVEC (basic_block, num_ssa_names);
579 enum dom_state orig_dom_state = dom_computed[CDI_DOMINATORS];
580 bitmap names_defined_in_bb = BITMAP_ALLOC (NULL);
582 gcc_assert (!need_ssa_update_p ());
586 timevar_push (TV_TREE_SSA_VERIFY);
588 /* Keep track of SSA names present in the IL. */
589 for (i = 1; i < num_ssa_names; i++)
591 tree name = ssa_name (i);
595 TREE_VISITED (name) = 0;
597 stmt = SSA_NAME_DEF_STMT (name);
598 if (!IS_EMPTY_STMT (stmt))
600 basic_block bb = bb_for_stmt (stmt);
601 verify_def (bb, definition_block,
602 name, stmt, !is_gimple_reg (name));
608 calculate_dominance_info (CDI_DOMINATORS);
610 /* Now verify all the uses and make sure they agree with the definitions
611 found in the previous pass. */
617 block_stmt_iterator bsi;
619 /* Make sure that all edges have a clear 'aux' field. */
620 FOR_EACH_EDGE (e, ei, bb->preds)
624 error ("AUX pointer initialized for edge %d->%d", e->src->index,
630 /* Verify the arguments for every PHI node in the block. */
631 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
633 if (verify_phi_args (phi, bb, definition_block))
636 bitmap_set_bit (names_defined_in_bb,
637 SSA_NAME_VERSION (PHI_RESULT (phi)));
640 /* Now verify all the uses and vuses in every statement of the block. */
641 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
643 tree stmt = bsi_stmt (bsi);
646 if (check_modified_stmt && stmt_modified_p (stmt))
648 error ("stmt (%p) marked modified after optimization pass: ",
650 print_generic_stmt (stderr, stmt, TDF_VOPS);
654 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
655 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 0)) != SSA_NAME)
657 tree lhs, base_address;
659 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
660 base_address = get_base_address (lhs);
663 && gimple_aliases_computed_p (cfun)
664 && SSA_VAR_P (base_address)
665 && !stmt_ann (stmt)->has_volatile_ops
666 && ZERO_SSA_OPERANDS (stmt, SSA_OP_VDEF))
668 error ("statement makes a memory store, but has no VDEFS");
669 print_generic_stmt (stderr, stmt, TDF_VOPS);
674 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_VIRTUALS)
676 if (verify_ssa_name (op, true))
678 error ("in statement");
679 print_generic_stmt (stderr, stmt, TDF_VOPS|TDF_MEMSYMS);
684 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE|SSA_OP_DEF)
686 if (verify_ssa_name (op, false))
688 error ("in statement");
689 print_generic_stmt (stderr, stmt, TDF_VOPS|TDF_MEMSYMS);
694 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE|SSA_OP_VUSE)
696 op = USE_FROM_PTR (use_p);
697 if (verify_use (bb, definition_block[SSA_NAME_VERSION (op)],
698 use_p, stmt, false, names_defined_in_bb))
702 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_DEFS)
703 bitmap_set_bit (names_defined_in_bb, SSA_NAME_VERSION (op));
706 bitmap_clear (names_defined_in_bb);
709 /* Finally, verify alias information. */
710 if (gimple_aliases_computed_p (cfun))
711 verify_alias_info ();
713 free (definition_block);
715 /* Restore the dominance information to its prior known state, so
716 that we do not perturb the compiler's subsequent behavior. */
717 if (orig_dom_state == DOM_NONE)
718 free_dominance_info (CDI_DOMINATORS);
720 dom_computed[CDI_DOMINATORS] = orig_dom_state;
722 BITMAP_FREE (names_defined_in_bb);
723 timevar_pop (TV_TREE_SSA_VERIFY);
727 internal_error ("verify_ssa failed");
730 /* Return true if the uid in both int tree maps are equal. */
733 int_tree_map_eq (const void *va, const void *vb)
735 const struct int_tree_map *a = (const struct int_tree_map *) va;
736 const struct int_tree_map *b = (const struct int_tree_map *) vb;
737 return (a->uid == b->uid);
740 /* Hash a UID in a int_tree_map. */
743 int_tree_map_hash (const void *item)
745 return ((const struct int_tree_map *)item)->uid;
748 /* Return true if the uid in both int tree maps are equal. */
751 var_ann_eq (const void *va, const void *vb)
753 const struct static_var_ann_d *a = (const struct static_var_ann_d *) va;
755 return (a->uid == DECL_UID (b));
758 /* Hash a UID in a int_tree_map. */
761 var_ann_hash (const void *item)
763 return ((const struct static_var_ann_d *)item)->uid;
767 /* Initialize global DFA and SSA structures. */
772 cfun->gimple_df = ggc_alloc_cleared (sizeof (struct gimple_df));
773 cfun->gimple_df->referenced_vars = htab_create_ggc (20, int_tree_map_hash,
774 int_tree_map_eq, NULL);
775 cfun->gimple_df->default_defs = htab_create_ggc (20, int_tree_map_hash,
776 int_tree_map_eq, NULL);
777 cfun->gimple_df->var_anns = htab_create_ggc (20, var_ann_hash,
779 cfun->gimple_df->call_clobbered_vars = BITMAP_GGC_ALLOC ();
780 cfun->gimple_df->addressable_vars = BITMAP_GGC_ALLOC ();
781 init_alias_heapvars ();
787 /* Deallocate memory associated with SSA data structures for FNDECL. */
790 delete_tree_ssa (void)
794 block_stmt_iterator bsi;
795 referenced_var_iterator rvi;
798 /* Release any ssa_names still in use. */
799 for (i = 0; i < num_ssa_names; i++)
801 tree var = ssa_name (i);
802 if (var && TREE_CODE (var) == SSA_NAME)
804 SSA_NAME_IMM_USE_NODE (var).prev = &(SSA_NAME_IMM_USE_NODE (var));
805 SSA_NAME_IMM_USE_NODE (var).next = &(SSA_NAME_IMM_USE_NODE (var));
807 release_ssa_name (var);
810 /* Remove annotations from every tree in the function. */
813 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
815 tree stmt = bsi_stmt (bsi);
816 stmt_ann_t ann = get_stmt_ann (stmt);
818 free_ssa_operands (&ann->operands);
819 ann->addresses_taken = 0;
820 mark_stmt_modified (stmt);
822 set_phi_nodes (bb, NULL);
825 /* Remove annotations from every referenced variable. */
826 FOR_EACH_REFERENCED_VAR (var, rvi)
829 ggc_free (var->base.ann);
830 var->base.ann = NULL;
832 htab_delete (gimple_referenced_vars (cfun));
833 cfun->gimple_df->referenced_vars = NULL;
838 cfun->gimple_df->global_var = NULL_TREE;
840 htab_delete (cfun->gimple_df->default_defs);
841 cfun->gimple_df->default_defs = NULL;
842 htab_delete (cfun->gimple_df->var_anns);
843 cfun->gimple_df->var_anns = NULL;
844 cfun->gimple_df->call_clobbered_vars = NULL;
845 cfun->gimple_df->addressable_vars = NULL;
846 cfun->gimple_df->modified_noreturn_calls = NULL;
847 cfun->gimple_df->aliases_computed_p = false;
849 delete_alias_heapvars ();
850 gcc_assert (!need_ssa_update_p ());
851 cfun->gimple_df = NULL;
855 /* Return true if the conversion from INNER_TYPE to OUTER_TYPE is a
856 useless type conversion, otherwise return false. */
859 tree_ssa_useless_type_conversion_1 (tree outer_type, tree inner_type)
861 if (inner_type == outer_type)
864 /* Changes in machine mode are never useless conversions. */
865 if (TYPE_MODE (inner_type) != TYPE_MODE (outer_type))
868 /* If the inner and outer types are effectively the same, then
869 strip the type conversion and enter the equivalence into
871 if (lang_hooks.types_compatible_p (inner_type, outer_type))
874 /* If both types are pointers and the outer type is a (void *), then
875 the conversion is not necessary. The opposite is not true since
876 that conversion would result in a loss of information if the
877 equivalence was used. Consider an indirect function call where
878 we need to know the exact type of the function to correctly
879 implement the ABI. */
880 else if (POINTER_TYPE_P (inner_type)
881 && POINTER_TYPE_P (outer_type)
882 && TYPE_REF_CAN_ALIAS_ALL (inner_type)
883 == TYPE_REF_CAN_ALIAS_ALL (outer_type)
884 && TREE_CODE (TREE_TYPE (outer_type)) == VOID_TYPE)
887 /* Don't lose casts between pointers to volatile and non-volatile
888 qualified types. Doing so would result in changing the semantics
889 of later accesses. */
890 else if (POINTER_TYPE_P (inner_type)
891 && POINTER_TYPE_P (outer_type)
892 && TYPE_VOLATILE (TREE_TYPE (outer_type))
893 != TYPE_VOLATILE (TREE_TYPE (inner_type)))
896 /* Pointers/references are equivalent if their pointed to types
897 are effectively the same. This allows to strip conversions between
898 pointer types with different type qualifiers. */
899 else if (POINTER_TYPE_P (inner_type)
900 && POINTER_TYPE_P (outer_type)
901 && TYPE_REF_CAN_ALIAS_ALL (inner_type)
902 == TYPE_REF_CAN_ALIAS_ALL (outer_type)
903 && lang_hooks.types_compatible_p (TREE_TYPE (inner_type),
904 TREE_TYPE (outer_type)))
907 /* If both the inner and outer types are integral types, then the
908 conversion is not necessary if they have the same mode and
909 signedness and precision, and both or neither are boolean. Some
910 code assumes an invariant that boolean types stay boolean and do
911 not become 1-bit bit-field types. Note that types with precision
912 not using all bits of the mode (such as bit-field types in C)
913 mean that testing of precision is necessary. */
914 else if (INTEGRAL_TYPE_P (inner_type)
915 && INTEGRAL_TYPE_P (outer_type)
916 && TYPE_UNSIGNED (inner_type) == TYPE_UNSIGNED (outer_type)
917 && TYPE_PRECISION (inner_type) == TYPE_PRECISION (outer_type)
918 && simple_cst_equal (TYPE_MAX_VALUE (inner_type), TYPE_MAX_VALUE (outer_type))
919 && simple_cst_equal (TYPE_MIN_VALUE (inner_type), TYPE_MIN_VALUE (outer_type)))
921 bool first_boolean = (TREE_CODE (inner_type) == BOOLEAN_TYPE);
922 bool second_boolean = (TREE_CODE (outer_type) == BOOLEAN_TYPE);
923 if (first_boolean == second_boolean)
927 /* Recurse for complex types. */
928 else if (TREE_CODE (inner_type) == COMPLEX_TYPE
929 && TREE_CODE (outer_type) == COMPLEX_TYPE
930 && tree_ssa_useless_type_conversion_1 (TREE_TYPE (outer_type),
931 TREE_TYPE (inner_type)))
937 /* Return true if EXPR is a useless type conversion, otherwise return
941 tree_ssa_useless_type_conversion (tree expr)
943 /* If we have an assignment that merely uses a NOP_EXPR to change
944 the top of the RHS to the type of the LHS and the type conversion
945 is "safe", then strip away the type conversion so that we can
946 enter LHS = RHS into the const_and_copies table. */
947 if (TREE_CODE (expr) == NOP_EXPR || TREE_CODE (expr) == CONVERT_EXPR
948 || TREE_CODE (expr) == VIEW_CONVERT_EXPR
949 || TREE_CODE (expr) == NON_LVALUE_EXPR)
950 return tree_ssa_useless_type_conversion_1 (TREE_TYPE (expr),
951 TREE_TYPE (TREE_OPERAND (expr,
959 /* Internal helper for walk_use_def_chains. VAR, FN and DATA are as
960 described in walk_use_def_chains.
962 VISITED is a pointer set used to mark visited SSA_NAMEs to avoid
963 infinite loops. We used to have a bitmap for this to just mark
964 SSA versions we had visited. But non-sparse bitmaps are way too
965 expensive, while sparse bitmaps may cause quadratic behavior.
967 IS_DFS is true if the caller wants to perform a depth-first search
968 when visiting PHI nodes. A DFS will visit each PHI argument and
969 call FN after each one. Otherwise, all the arguments are
970 visited first and then FN is called with each of the visited
971 arguments in a separate pass. */
974 walk_use_def_chains_1 (tree var, walk_use_def_chains_fn fn, void *data,
975 struct pointer_set_t *visited, bool is_dfs)
979 if (pointer_set_insert (visited, var))
982 def_stmt = SSA_NAME_DEF_STMT (var);
984 if (TREE_CODE (def_stmt) != PHI_NODE)
986 /* If we reached the end of the use-def chain, call FN. */
987 return fn (var, def_stmt, data);
993 /* When doing a breadth-first search, call FN before following the
994 use-def links for each argument. */
996 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
997 if (fn (PHI_ARG_DEF (def_stmt, i), def_stmt, data))
1000 /* Follow use-def links out of each PHI argument. */
1001 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
1003 tree arg = PHI_ARG_DEF (def_stmt, i);
1005 /* ARG may be NULL for newly introduced PHI nodes. */
1007 && TREE_CODE (arg) == SSA_NAME
1008 && walk_use_def_chains_1 (arg, fn, data, visited, is_dfs))
1012 /* When doing a depth-first search, call FN after following the
1013 use-def links for each argument. */
1015 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
1016 if (fn (PHI_ARG_DEF (def_stmt, i), def_stmt, data))
1025 /* Walk use-def chains starting at the SSA variable VAR. Call
1026 function FN at each reaching definition found. FN takes three
1027 arguments: VAR, its defining statement (DEF_STMT) and a generic
1028 pointer to whatever state information that FN may want to maintain
1029 (DATA). FN is able to stop the walk by returning true, otherwise
1030 in order to continue the walk, FN should return false.
1032 Note, that if DEF_STMT is a PHI node, the semantics are slightly
1033 different. The first argument to FN is no longer the original
1034 variable VAR, but the PHI argument currently being examined. If FN
1035 wants to get at VAR, it should call PHI_RESULT (PHI).
1037 If IS_DFS is true, this function will:
1039 1- walk the use-def chains for all the PHI arguments, and,
1040 2- call (*FN) (ARG, PHI, DATA) on all the PHI arguments.
1042 If IS_DFS is false, the two steps above are done in reverse order
1043 (i.e., a breadth-first search). */
1046 walk_use_def_chains (tree var, walk_use_def_chains_fn fn, void *data,
1051 gcc_assert (TREE_CODE (var) == SSA_NAME);
1053 def_stmt = SSA_NAME_DEF_STMT (var);
1055 /* We only need to recurse if the reaching definition comes from a PHI
1057 if (TREE_CODE (def_stmt) != PHI_NODE)
1058 (*fn) (var, def_stmt, data);
1061 struct pointer_set_t *visited = pointer_set_create ();
1062 walk_use_def_chains_1 (var, fn, data, visited, is_dfs);
1063 pointer_set_destroy (visited);
1068 /* Emit warnings for uninitialized variables. This is done in two passes.
1070 The first pass notices real uses of SSA names with default definitions.
1071 Such uses are unconditionally uninitialized, and we can be certain that
1072 such a use is a mistake. This pass is run before most optimizations,
1073 so that we catch as many as we can.
1075 The second pass follows PHI nodes to find uses that are potentially
1076 uninitialized. In this case we can't necessarily prove that the use
1077 is really uninitialized. This pass is run after most optimizations,
1078 so that we thread as many jumps and possible, and delete as much dead
1079 code as possible, in order to reduce false positives. We also look
1080 again for plain uninitialized variables, since optimization may have
1081 changed conditionally uninitialized to unconditionally uninitialized. */
1083 /* Emit a warning for T, an SSA_NAME, being uninitialized. The exact
1084 warning text is in MSGID and LOCUS may contain a location or be null. */
1087 warn_uninit (tree t, const char *gmsgid, void *data)
1089 tree var = SSA_NAME_VAR (t);
1090 tree def = SSA_NAME_DEF_STMT (t);
1091 tree context = (tree) data;
1093 expanded_location xloc, floc;
1095 /* Default uses (indicated by an empty definition statement),
1096 are uninitialized. */
1097 if (!IS_EMPTY_STMT (def))
1100 /* Except for PARMs of course, which are always initialized. */
1101 if (TREE_CODE (var) == PARM_DECL)
1104 /* Hard register variables get their initial value from the ether. */
1105 if (TREE_CODE (var) == VAR_DECL && DECL_HARD_REGISTER (var))
1108 /* TREE_NO_WARNING either means we already warned, or the front end
1109 wishes to suppress the warning. */
1110 if (TREE_NO_WARNING (var))
1113 locus = (context != NULL && EXPR_HAS_LOCATION (context)
1114 ? EXPR_LOCUS (context)
1115 : &DECL_SOURCE_LOCATION (var));
1116 warning (0, gmsgid, locus, var);
1117 xloc = expand_location (*locus);
1118 floc = expand_location (DECL_SOURCE_LOCATION (cfun->decl));
1119 if (xloc.file != floc.file
1120 || xloc.line < floc.line
1121 || xloc.line > LOCATION_LINE (cfun->function_end_locus))
1122 inform ("%J%qD was declared here", var, var);
1124 TREE_NO_WARNING (var) = 1;
1127 /* Called via walk_tree, look for SSA_NAMEs that have empty definitions
1128 and warn about them. */
1131 warn_uninitialized_var (tree *tp, int *walk_subtrees, void *data)
1135 switch (TREE_CODE (t))
1138 /* We only do data flow with SSA_NAMEs, so that's all we
1140 warn_uninit (t, "%H%qD is used uninitialized in this function", data);
1146 /* The total store transformation performed during gimplification
1147 creates uninitialized variable uses. If all is well, these will
1148 be optimized away, so don't warn now. */
1149 if (TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME)
1154 if (IS_TYPE_OR_DECL_P (t))
1162 /* Look for inputs to PHI that are SSA_NAMEs that have empty definitions
1163 and warn about them. */
1166 warn_uninitialized_phi (tree phi)
1168 int i, n = PHI_NUM_ARGS (phi);
1170 /* Don't look at memory tags. */
1171 if (!is_gimple_reg (PHI_RESULT (phi)))
1174 for (i = 0; i < n; ++i)
1176 tree op = PHI_ARG_DEF (phi, i);
1177 if (TREE_CODE (op) == SSA_NAME)
1178 warn_uninit (op, "%H%qD may be used uninitialized in this function",
1184 execute_early_warn_uninitialized (void)
1186 block_stmt_iterator bsi;
1190 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1192 tree context = bsi_stmt (bsi);
1193 walk_tree (bsi_stmt_ptr (bsi), warn_uninitialized_var,
1200 execute_late_warn_uninitialized (void)
1205 /* Re-do the plain uninitialized variable check, as optimization may have
1206 straightened control flow. Do this first so that we don't accidentally
1207 get a "may be" warning when we'd have seen an "is" warning later. */
1208 execute_early_warn_uninitialized ();
1211 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
1212 warn_uninitialized_phi (phi);
1217 gate_warn_uninitialized (void)
1219 return warn_uninitialized != 0;
1222 struct tree_opt_pass pass_early_warn_uninitialized =
1225 gate_warn_uninitialized, /* gate */
1226 execute_early_warn_uninitialized, /* execute */
1229 0, /* static_pass_number */
1231 PROP_ssa, /* properties_required */
1232 0, /* properties_provided */
1233 0, /* properties_destroyed */
1234 0, /* todo_flags_start */
1235 0, /* todo_flags_finish */
1239 struct tree_opt_pass pass_late_warn_uninitialized =
1242 gate_warn_uninitialized, /* gate */
1243 execute_late_warn_uninitialized, /* execute */
1246 0, /* static_pass_number */
1248 PROP_ssa, /* properties_required */
1249 0, /* properties_provided */
1250 0, /* properties_destroyed */
1251 0, /* todo_flags_start */
1252 0, /* todo_flags_finish */