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 VEC(tree
,gc
) *may_aliases
;
388 may_aliases
= ann
->may_aliases
;
390 for (j
= 0; VEC_iterate (tree
, may_aliases
, j
, alias
); j
++)
392 bitmap_set_bit (visited
, DECL_UID (alias
));
394 if (!may_be_aliased (alias
))
396 error ("non-addressable variable inside an alias set");
397 debug_variable (alias
);
403 FOR_EACH_REFERENCED_VAR (var
, rvi
)
410 && !bitmap_bit_p (visited
, DECL_UID (var
)))
412 error ("addressable variable that is aliased but is not in any alias set");
417 BITMAP_FREE (visited
);
421 debug_variable (var
);
422 internal_error ("verify_flow_insensitive_alias_info failed");
427 verify_flow_sensitive_alias_info (void)
432 for (i
= 1; i
< num_ssa_names
; i
++)
436 struct ptr_info_def
*pi
;
443 /* We only care for pointers that are actually referenced in the
445 if (!POINTER_TYPE_P (TREE_TYPE (ptr
)) || !TREE_VISITED (ptr
))
448 /* RESULT_DECL is special. If it's a GIMPLE register, then it
449 is only written-to only once in the return statement.
450 Otherwise, aggregate RESULT_DECLs may be written-to more than
451 once in virtual operands. */
452 var
= SSA_NAME_VAR (ptr
);
453 if (TREE_CODE (var
) == RESULT_DECL
454 && is_gimple_reg (ptr
))
457 pi
= SSA_NAME_PTR_INFO (ptr
);
462 if (pi
->is_dereferenced
&& !pi
->name_mem_tag
&& !ann
->symbol_mem_tag
)
464 error ("dereferenced pointers should have a name or a symbol tag");
469 && (pi
->pt_vars
== NULL
|| bitmap_empty_p (pi
->pt_vars
)))
471 error ("pointers with a memory tag, should have points-to sets");
475 if (pi
->value_escapes_p
477 && !is_call_clobbered (pi
->name_mem_tag
))
479 error ("pointer escapes but its name tag is not call-clobbered");
487 debug_variable (ptr
);
488 internal_error ("verify_flow_sensitive_alias_info failed");
492 DEF_VEC_ALLOC_P (bitmap
,heap
);
494 /* Verify that all name tags have different points to sets.
495 This algorithm takes advantage of the fact that every variable with the
496 same name tag must have the same points-to set.
497 So we check a single variable for each name tag, and verify that its
498 points-to set is different from every other points-to set for other name
501 Additionally, given a pointer P_i with name tag NMT and symbol tag
502 SMT, this function verified the alias set of SMT is a superset of
503 the alias set of NMT. */
506 verify_name_tags (void)
510 bitmap first
, second
;
511 VEC(tree
,heap
) *name_tag_reps
= NULL
;
512 VEC(bitmap
,heap
) *pt_vars_for_reps
= NULL
;
513 bitmap type_aliases
= BITMAP_ALLOC (NULL
);
515 /* First we compute the name tag representatives and their points-to sets. */
516 for (i
= 0; i
< num_ssa_names
; i
++)
518 struct ptr_info_def
*pi
;
519 tree smt
, ptr
= ssa_name (i
);
521 if (ptr
== NULL_TREE
)
524 pi
= SSA_NAME_PTR_INFO (ptr
);
526 if (!TREE_VISITED (ptr
)
527 || !POINTER_TYPE_P (TREE_TYPE (ptr
))
530 || TREE_VISITED (pi
->name_mem_tag
))
533 TREE_VISITED (pi
->name_mem_tag
) = 1;
535 if (pi
->pt_vars
== NULL
)
538 VEC_safe_push (tree
, heap
, name_tag_reps
, ptr
);
539 VEC_safe_push (bitmap
, heap
, pt_vars_for_reps
, pi
->pt_vars
);
541 /* Verify that alias set of PTR's symbol tag is a superset of the
542 alias set of PTR's name tag. */
543 smt
= var_ann (SSA_NAME_VAR (ptr
))->symbol_mem_tag
;
547 VEC(tree
,gc
) *aliases
= var_ann (smt
)->may_aliases
;
550 bitmap_clear (type_aliases
);
551 for (i
= 0; VEC_iterate (tree
, aliases
, i
, alias
); i
++)
552 bitmap_set_bit (type_aliases
, DECL_UID (alias
));
554 /* When grouping, we may have added PTR's symbol tag into the
555 alias set of PTR's name tag. To prevent a false
556 positive, pretend that SMT is in its own alias set. */
557 bitmap_set_bit (type_aliases
, DECL_UID (smt
));
559 if (bitmap_equal_p (type_aliases
, pi
->pt_vars
))
562 if (!bitmap_intersect_compl_p (type_aliases
, pi
->pt_vars
))
564 error ("alias set of a pointer's symbol tag should be a superset of the corresponding name tag");
565 debug_variable (smt
);
566 debug_variable (pi
->name_mem_tag
);
572 /* Now compare all the representative bitmaps with all other representative
573 bitmaps, to verify that they are all different. */
574 for (i
= 0; VEC_iterate (bitmap
, pt_vars_for_reps
, i
, first
); i
++)
576 for (j
= i
+ 1; VEC_iterate (bitmap
, pt_vars_for_reps
, j
, second
); j
++)
578 if (bitmap_equal_p (first
, second
))
580 error ("two different pointers with identical points-to sets but different name tags");
581 debug_variable (VEC_index (tree
, name_tag_reps
, j
));
587 /* Lastly, clear out the visited flags. */
588 for (i
= 0; i
< num_ssa_names
; i
++)
592 tree ptr
= ssa_name (i
);
593 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (ptr
);
594 if (!TREE_VISITED (ptr
)
595 || !POINTER_TYPE_P (TREE_TYPE (ptr
))
597 || !pi
->name_mem_tag
)
599 TREE_VISITED (pi
->name_mem_tag
) = 0;
603 /* We do not have to free the bitmaps or trees in the vectors, as
604 they are not owned by us. */
605 VEC_free (bitmap
, heap
, pt_vars_for_reps
);
606 VEC_free (tree
, heap
, name_tag_reps
);
607 BITMAP_FREE (type_aliases
);
611 debug_variable (VEC_index (tree
, name_tag_reps
, i
));
612 internal_error ("verify_name_tags failed");
616 /* Verify the consistency of call clobbering information. */
618 verify_call_clobbering (void)
623 referenced_var_iterator rvi
;
625 /* At all times, the result of the DECL_CALL_CLOBBERED flag should
626 match the result of the call_clobbered_vars bitmap. Verify both
627 that everything in call_clobbered_vars is marked
628 DECL_CALL_CLOBBERED, and that everything marked
629 DECL_CALL_CLOBBERED is in call_clobbered_vars. */
630 EXECUTE_IF_SET_IN_BITMAP (call_clobbered_vars
, 0, i
, bi
)
632 var
= referenced_var (i
);
633 if (!MTAG_P (var
) && !DECL_CALL_CLOBBERED (var
))
635 error ("variable in call_clobbered_vars but not marked DECL_CALL_CLOBBERED");
636 debug_variable (var
);
640 FOR_EACH_REFERENCED_VAR (var
, rvi
)
642 if (!MTAG_P (var
) && DECL_CALL_CLOBBERED (var
)
643 && !bitmap_bit_p (call_clobbered_vars
, DECL_UID (var
)))
645 error ("variable marked DECL_CALL_CLOBBERED but not in call_clobbered_vars bitmap.");
646 debug_variable (var
);
653 internal_error ("verify_call_clobbering failed");
656 /* Verify the consistency of aliasing information. */
659 verify_alias_info (void)
661 verify_flow_sensitive_alias_info ();
663 verify_call_clobbering ();
664 verify_flow_insensitive_alias_info ();
668 /* Verify common invariants in the SSA web.
669 TODO: verify the variable annotations. */
672 verify_ssa (bool check_modified_stmt
)
676 basic_block
*definition_block
= XCNEWVEC (basic_block
, num_ssa_names
);
679 enum dom_state orig_dom_state
= dom_computed
[CDI_DOMINATORS
];
680 bitmap names_defined_in_bb
= BITMAP_ALLOC (NULL
);
682 gcc_assert (!need_ssa_update_p ());
686 timevar_push (TV_TREE_SSA_VERIFY
);
688 /* Keep track of SSA names present in the IL. */
689 for (i
= 1; i
< num_ssa_names
; i
++)
691 tree name
= ssa_name (i
);
695 TREE_VISITED (name
) = 0;
697 stmt
= SSA_NAME_DEF_STMT (name
);
698 if (!IS_EMPTY_STMT (stmt
))
700 basic_block bb
= bb_for_stmt (stmt
);
701 verify_def (bb
, definition_block
,
702 name
, stmt
, !is_gimple_reg (name
));
708 calculate_dominance_info (CDI_DOMINATORS
);
710 /* Now verify all the uses and make sure they agree with the definitions
711 found in the previous pass. */
717 block_stmt_iterator bsi
;
719 /* Make sure that all edges have a clear 'aux' field. */
720 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
724 error ("AUX pointer initialized for edge %d->%d", e
->src
->index
,
730 /* Verify the arguments for every PHI node in the block. */
731 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
733 if (verify_phi_args (phi
, bb
, definition_block
))
735 bitmap_set_bit (names_defined_in_bb
,
736 SSA_NAME_VERSION (PHI_RESULT (phi
)));
739 /* Now verify all the uses and vuses in every statement of the block. */
740 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
742 tree stmt
= bsi_stmt (bsi
);
745 if (check_modified_stmt
&& stmt_modified_p (stmt
))
747 error ("stmt (%p) marked modified after optimization pass : ",
749 print_generic_stmt (stderr
, stmt
, TDF_VOPS
);
753 if (TREE_CODE (stmt
) == MODIFY_EXPR
754 && TREE_CODE (TREE_OPERAND (stmt
, 0)) != SSA_NAME
)
756 tree lhs
, base_address
;
758 lhs
= TREE_OPERAND (stmt
, 0);
759 base_address
= get_base_address (lhs
);
762 && SSA_VAR_P (base_address
)
763 && ZERO_SSA_OPERANDS (stmt
, SSA_OP_VMAYDEF
|SSA_OP_VMUSTDEF
))
765 error ("statement makes a memory store, but has no "
766 "V_MAY_DEFS nor V_MUST_DEFS");
767 print_generic_stmt (stderr
, stmt
, TDF_VOPS
);
772 FOR_EACH_SSA_USE_OPERAND (use_p
, stmt
, iter
,
773 SSA_OP_ALL_USES
| SSA_OP_ALL_KILLS
)
775 op
= USE_FROM_PTR (use_p
);
776 if (verify_use (bb
, definition_block
[SSA_NAME_VERSION (op
)],
777 use_p
, stmt
, false, !is_gimple_reg (op
),
778 names_defined_in_bb
))
782 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, iter
, SSA_OP_ALL_DEFS
)
783 bitmap_set_bit (names_defined_in_bb
, SSA_NAME_VERSION (op
));
786 bitmap_clear (names_defined_in_bb
);
789 /* Finally, verify alias information. */
790 verify_alias_info ();
792 free (definition_block
);
794 /* Restore the dominance information to its prior known state, so
795 that we do not perturb the compiler's subsequent behavior. */
796 if (orig_dom_state
== DOM_NONE
)
797 free_dominance_info (CDI_DOMINATORS
);
799 dom_computed
[CDI_DOMINATORS
] = orig_dom_state
;
801 BITMAP_FREE (names_defined_in_bb
);
802 timevar_pop (TV_TREE_SSA_VERIFY
);
806 internal_error ("verify_ssa failed");
809 /* Return true if the uid in both int tree maps are equal. */
812 int_tree_map_eq (const void *va
, const void *vb
)
814 const struct int_tree_map
*a
= (const struct int_tree_map
*) va
;
815 const struct int_tree_map
*b
= (const struct int_tree_map
*) vb
;
816 return (a
->uid
== b
->uid
);
819 /* Hash a UID in a int_tree_map. */
822 int_tree_map_hash (const void *item
)
824 return ((const struct int_tree_map
*)item
)->uid
;
828 /* Initialize global DFA and SSA structures. */
833 referenced_vars
= htab_create_ggc (20, int_tree_map_hash
,
834 int_tree_map_eq
, NULL
);
835 default_defs
= htab_create_ggc (20, int_tree_map_hash
, int_tree_map_eq
, NULL
);
836 call_clobbered_vars
= BITMAP_ALLOC (NULL
);
837 addressable_vars
= BITMAP_ALLOC (NULL
);
838 init_alias_heapvars ();
841 global_var
= NULL_TREE
;
842 aliases_computed_p
= false;
846 /* Deallocate memory associated with SSA data structures for FNDECL. */
849 delete_tree_ssa (void)
853 block_stmt_iterator bsi
;
854 referenced_var_iterator rvi
;
857 /* Release any ssa_names still in use. */
858 for (i
= 0; i
< num_ssa_names
; i
++)
860 tree var
= ssa_name (i
);
861 if (var
&& TREE_CODE (var
) == SSA_NAME
)
863 SSA_NAME_IMM_USE_NODE (var
).prev
= &(SSA_NAME_IMM_USE_NODE (var
));
864 SSA_NAME_IMM_USE_NODE (var
).next
= &(SSA_NAME_IMM_USE_NODE (var
));
866 release_ssa_name (var
);
869 /* Remove annotations from every tree in the function. */
872 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
874 tree stmt
= bsi_stmt (bsi
);
875 stmt_ann_t ann
= get_stmt_ann (stmt
);
877 free_ssa_operands (&ann
->operands
);
878 ann
->addresses_taken
= 0;
879 mark_stmt_modified (stmt
);
881 set_phi_nodes (bb
, NULL
);
884 /* Remove annotations from every referenced variable. */
885 FOR_EACH_REFERENCED_VAR (var
, rvi
)
887 ggc_free (var
->common
.ann
);
888 var
->common
.ann
= NULL
;
890 htab_delete (referenced_vars
);
891 referenced_vars
= NULL
;
896 global_var
= NULL_TREE
;
898 htab_delete (default_defs
);
899 BITMAP_FREE (call_clobbered_vars
);
900 call_clobbered_vars
= NULL
;
901 BITMAP_FREE (addressable_vars
);
902 addressable_vars
= NULL
;
903 modified_noreturn_calls
= NULL
;
904 aliases_computed_p
= false;
905 delete_alias_heapvars ();
906 gcc_assert (!need_ssa_update_p ());
910 /* Return true if the conversion from INNER_TYPE to OUTER_TYPE is a
911 useless type conversion, otherwise return false. */
914 tree_ssa_useless_type_conversion_1 (tree outer_type
, tree inner_type
)
916 if (inner_type
== outer_type
)
919 /* Changes in machine mode are never useless conversions. */
920 if (TYPE_MODE (inner_type
) != TYPE_MODE (outer_type
))
923 /* If the inner and outer types are effectively the same, then
924 strip the type conversion and enter the equivalence into
926 if (lang_hooks
.types_compatible_p (inner_type
, outer_type
))
929 /* If both types are pointers and the outer type is a (void *), then
930 the conversion is not necessary. The opposite is not true since
931 that conversion would result in a loss of information if the
932 equivalence was used. Consider an indirect function call where
933 we need to know the exact type of the function to correctly
934 implement the ABI. */
935 else if (POINTER_TYPE_P (inner_type
)
936 && POINTER_TYPE_P (outer_type
)
937 && TYPE_REF_CAN_ALIAS_ALL (inner_type
)
938 == TYPE_REF_CAN_ALIAS_ALL (outer_type
)
939 && TREE_CODE (TREE_TYPE (outer_type
)) == VOID_TYPE
)
942 /* Don't lose casts between pointers to volatile and non-volatile
943 qualified types. Doing so would result in changing the semantics
944 of later accesses. */
945 else if (POINTER_TYPE_P (inner_type
)
946 && POINTER_TYPE_P (outer_type
)
947 && TYPE_VOLATILE (TREE_TYPE (outer_type
))
948 != TYPE_VOLATILE (TREE_TYPE (inner_type
)))
951 /* Pointers/references are equivalent if their pointed to types
952 are effectively the same. This allows to strip conversions between
953 pointer types with different type qualifiers. */
954 else if (POINTER_TYPE_P (inner_type
)
955 && POINTER_TYPE_P (outer_type
)
956 && TYPE_REF_CAN_ALIAS_ALL (inner_type
)
957 == TYPE_REF_CAN_ALIAS_ALL (outer_type
)
958 && lang_hooks
.types_compatible_p (TREE_TYPE (inner_type
),
959 TREE_TYPE (outer_type
)))
962 /* If both the inner and outer types are integral types, then the
963 conversion is not necessary if they have the same mode and
964 signedness and precision, and both or neither are boolean. Some
965 code assumes an invariant that boolean types stay boolean and do
966 not become 1-bit bit-field types. Note that types with precision
967 not using all bits of the mode (such as bit-field types in C)
968 mean that testing of precision is necessary. */
969 else if (INTEGRAL_TYPE_P (inner_type
)
970 && INTEGRAL_TYPE_P (outer_type
)
971 && TYPE_UNSIGNED (inner_type
) == TYPE_UNSIGNED (outer_type
)
972 && TYPE_PRECISION (inner_type
) == TYPE_PRECISION (outer_type
)
973 && simple_cst_equal (TYPE_MAX_VALUE (inner_type
), TYPE_MAX_VALUE (outer_type
))
974 && simple_cst_equal (TYPE_MIN_VALUE (inner_type
), TYPE_MIN_VALUE (outer_type
)))
976 bool first_boolean
= (TREE_CODE (inner_type
) == BOOLEAN_TYPE
);
977 bool second_boolean
= (TREE_CODE (outer_type
) == BOOLEAN_TYPE
);
978 if (first_boolean
== second_boolean
)
982 /* Recurse for complex types. */
983 else if (TREE_CODE (inner_type
) == COMPLEX_TYPE
984 && TREE_CODE (outer_type
) == COMPLEX_TYPE
985 && tree_ssa_useless_type_conversion_1 (TREE_TYPE (outer_type
),
986 TREE_TYPE (inner_type
)))
992 /* Return true if EXPR is a useless type conversion, otherwise return
996 tree_ssa_useless_type_conversion (tree expr
)
998 /* If we have an assignment that merely uses a NOP_EXPR to change
999 the top of the RHS to the type of the LHS and the type conversion
1000 is "safe", then strip away the type conversion so that we can
1001 enter LHS = RHS into the const_and_copies table. */
1002 if (TREE_CODE (expr
) == NOP_EXPR
|| TREE_CODE (expr
) == CONVERT_EXPR
1003 || TREE_CODE (expr
) == VIEW_CONVERT_EXPR
1004 || TREE_CODE (expr
) == NON_LVALUE_EXPR
)
1005 return tree_ssa_useless_type_conversion_1 (TREE_TYPE (expr
),
1006 TREE_TYPE (TREE_OPERAND (expr
,
1013 /* Returns true if statement STMT may read memory. */
1016 stmt_references_memory_p (tree stmt
)
1018 stmt_ann_t ann
= stmt_ann (stmt
);
1020 if (ann
->has_volatile_ops
)
1023 return (!ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
));
1026 /* Internal helper for walk_use_def_chains. VAR, FN and DATA are as
1027 described in walk_use_def_chains.
1029 VISITED is a pointer set used to mark visited SSA_NAMEs to avoid
1030 infinite loops. We used to have a bitmap for this to just mark
1031 SSA versions we had visited. But non-sparse bitmaps are way too
1032 expensive, while sparse bitmaps may cause quadratic behavior.
1034 IS_DFS is true if the caller wants to perform a depth-first search
1035 when visiting PHI nodes. A DFS will visit each PHI argument and
1036 call FN after each one. Otherwise, all the arguments are
1037 visited first and then FN is called with each of the visited
1038 arguments in a separate pass. */
1041 walk_use_def_chains_1 (tree var
, walk_use_def_chains_fn fn
, void *data
,
1042 struct pointer_set_t
*visited
, bool is_dfs
)
1046 if (pointer_set_insert (visited
, var
))
1049 def_stmt
= SSA_NAME_DEF_STMT (var
);
1051 if (TREE_CODE (def_stmt
) != PHI_NODE
)
1053 /* If we reached the end of the use-def chain, call FN. */
1054 return fn (var
, def_stmt
, data
);
1060 /* When doing a breadth-first search, call FN before following the
1061 use-def links for each argument. */
1063 for (i
= 0; i
< PHI_NUM_ARGS (def_stmt
); i
++)
1064 if (fn (PHI_ARG_DEF (def_stmt
, i
), def_stmt
, data
))
1067 /* Follow use-def links out of each PHI argument. */
1068 for (i
= 0; i
< PHI_NUM_ARGS (def_stmt
); i
++)
1070 tree arg
= PHI_ARG_DEF (def_stmt
, i
);
1071 if (TREE_CODE (arg
) == SSA_NAME
1072 && walk_use_def_chains_1 (arg
, fn
, data
, visited
, is_dfs
))
1076 /* When doing a depth-first search, call FN after following the
1077 use-def links for each argument. */
1079 for (i
= 0; i
< PHI_NUM_ARGS (def_stmt
); i
++)
1080 if (fn (PHI_ARG_DEF (def_stmt
, i
), def_stmt
, data
))
1089 /* Walk use-def chains starting at the SSA variable VAR. Call
1090 function FN at each reaching definition found. FN takes three
1091 arguments: VAR, its defining statement (DEF_STMT) and a generic
1092 pointer to whatever state information that FN may want to maintain
1093 (DATA). FN is able to stop the walk by returning true, otherwise
1094 in order to continue the walk, FN should return false.
1096 Note, that if DEF_STMT is a PHI node, the semantics are slightly
1097 different. The first argument to FN is no longer the original
1098 variable VAR, but the PHI argument currently being examined. If FN
1099 wants to get at VAR, it should call PHI_RESULT (PHI).
1101 If IS_DFS is true, this function will:
1103 1- walk the use-def chains for all the PHI arguments, and,
1104 2- call (*FN) (ARG, PHI, DATA) on all the PHI arguments.
1106 If IS_DFS is false, the two steps above are done in reverse order
1107 (i.e., a breadth-first search). */
1111 walk_use_def_chains (tree var
, walk_use_def_chains_fn fn
, void *data
,
1116 gcc_assert (TREE_CODE (var
) == SSA_NAME
);
1118 def_stmt
= SSA_NAME_DEF_STMT (var
);
1120 /* We only need to recurse if the reaching definition comes from a PHI
1122 if (TREE_CODE (def_stmt
) != PHI_NODE
)
1123 (*fn
) (var
, def_stmt
, data
);
1126 struct pointer_set_t
*visited
= pointer_set_create ();
1127 walk_use_def_chains_1 (var
, fn
, data
, visited
, is_dfs
);
1128 pointer_set_destroy (visited
);
1133 /* Emit warnings for uninitialized variables. This is done in two passes.
1135 The first pass notices real uses of SSA names with default definitions.
1136 Such uses are unconditionally uninitialized, and we can be certain that
1137 such a use is a mistake. This pass is run before most optimizations,
1138 so that we catch as many as we can.
1140 The second pass follows PHI nodes to find uses that are potentially
1141 uninitialized. In this case we can't necessarily prove that the use
1142 is really uninitialized. This pass is run after most optimizations,
1143 so that we thread as many jumps and possible, and delete as much dead
1144 code as possible, in order to reduce false positives. We also look
1145 again for plain uninitialized variables, since optimization may have
1146 changed conditionally uninitialized to unconditionally uninitialized. */
1148 /* Emit a warning for T, an SSA_NAME, being uninitialized. The exact
1149 warning text is in MSGID and LOCUS may contain a location or be null. */
1152 warn_uninit (tree t
, const char *gmsgid
, void *data
)
1154 tree var
= SSA_NAME_VAR (t
);
1155 tree def
= SSA_NAME_DEF_STMT (t
);
1156 tree context
= (tree
) data
;
1158 expanded_location xloc
, floc
;
1160 /* Default uses (indicated by an empty definition statement),
1161 are uninitialized. */
1162 if (!IS_EMPTY_STMT (def
))
1165 /* Except for PARMs of course, which are always initialized. */
1166 if (TREE_CODE (var
) == PARM_DECL
)
1169 /* Hard register variables get their initial value from the ether. */
1170 if (TREE_CODE (var
) == VAR_DECL
&& DECL_HARD_REGISTER (var
))
1173 /* TREE_NO_WARNING either means we already warned, or the front end
1174 wishes to suppress the warning. */
1175 if (TREE_NO_WARNING (var
))
1178 locus
= (context
!= NULL
&& EXPR_HAS_LOCATION (context
)
1179 ? EXPR_LOCUS (context
)
1180 : &DECL_SOURCE_LOCATION (var
));
1181 warning (0, gmsgid
, locus
, var
);
1182 xloc
= expand_location (*locus
);
1183 floc
= expand_location (DECL_SOURCE_LOCATION (cfun
->decl
));
1184 if (xloc
.file
!= floc
.file
1185 || xloc
.line
< floc
.line
1186 || xloc
.line
> LOCATION_LINE (cfun
->function_end_locus
))
1187 inform ("%J%qD was declared here", var
, var
);
1189 TREE_NO_WARNING (var
) = 1;
1192 /* Called via walk_tree, look for SSA_NAMEs that have empty definitions
1193 and warn about them. */
1196 warn_uninitialized_var (tree
*tp
, int *walk_subtrees
, void *data
)
1200 switch (TREE_CODE (t
))
1203 /* We only do data flow with SSA_NAMEs, so that's all we
1205 warn_uninit (t
, "%H%qD is used uninitialized in this function", data
);
1211 /* The total store transformation performed during gimplification
1212 creates uninitialized variable uses. If all is well, these will
1213 be optimized away, so don't warn now. */
1214 if (TREE_CODE (TREE_OPERAND (t
, 0)) == SSA_NAME
)
1219 if (IS_TYPE_OR_DECL_P (t
))
1227 /* Look for inputs to PHI that are SSA_NAMEs that have empty definitions
1228 and warn about them. */
1231 warn_uninitialized_phi (tree phi
)
1233 int i
, n
= PHI_NUM_ARGS (phi
);
1235 /* Don't look at memory tags. */
1236 if (!is_gimple_reg (PHI_RESULT (phi
)))
1239 for (i
= 0; i
< n
; ++i
)
1241 tree op
= PHI_ARG_DEF (phi
, i
);
1242 if (TREE_CODE (op
) == SSA_NAME
)
1243 warn_uninit (op
, "%H%qD may be used uninitialized in this function",
1249 execute_early_warn_uninitialized (void)
1251 block_stmt_iterator bsi
;
1255 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1257 tree context
= bsi_stmt (bsi
);
1258 walk_tree (bsi_stmt_ptr (bsi
), warn_uninitialized_var
,
1265 execute_late_warn_uninitialized (void)
1270 /* Re-do the plain uninitialized variable check, as optimization may have
1271 straightened control flow. Do this first so that we don't accidentally
1272 get a "may be" warning when we'd have seen an "is" warning later. */
1273 execute_early_warn_uninitialized ();
1276 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
1277 warn_uninitialized_phi (phi
);
1282 gate_warn_uninitialized (void)
1284 return warn_uninitialized
!= 0;
1287 struct tree_opt_pass pass_early_warn_uninitialized
=
1290 gate_warn_uninitialized
, /* gate */
1291 execute_early_warn_uninitialized
, /* execute */
1294 0, /* static_pass_number */
1296 PROP_ssa
, /* properties_required */
1297 0, /* properties_provided */
1298 0, /* properties_destroyed */
1299 0, /* todo_flags_start */
1300 0, /* todo_flags_finish */
1304 struct tree_opt_pass pass_late_warn_uninitialized
=
1307 gate_warn_uninitialized
, /* gate */
1308 execute_late_warn_uninitialized
, /* execute */
1311 0, /* static_pass_number */
1313 PROP_ssa
, /* properties_required */
1314 0, /* properties_provided */
1315 0, /* properties_destroyed */
1316 0, /* todo_flags_start */
1317 0, /* todo_flags_finish */