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, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
23 #include "coretypes.h"
30 #include "langhooks.h"
31 #include "hard-reg-set.h"
32 #include "basic-block.h"
37 #include "diagnostic.h"
39 #include "pointer-set.h"
40 #include "tree-flow.h"
41 #include "tree-gimple.h"
42 #include "tree-inline.h"
46 #include "tree-dump.h"
47 #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\n");
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\n",
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\n",
349 e
->src
->index
, e
->dest
->index
, bb
->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)
378 bitmap visited
= BITMAP_ALLOC (NULL
);
380 for (i
= 0; i
< num_referenced_vars
; i
++)
384 varray_type may_aliases
;
386 var
= referenced_var (i
);
388 may_aliases
= ann
->may_aliases
;
390 for (j
= 0; may_aliases
&& j
< VARRAY_ACTIVE_SIZE (may_aliases
); j
++)
392 tree alias
= VARRAY_TREE (may_aliases
, j
);
394 bitmap_set_bit (visited
, var_ann (alias
)->uid
);
396 if (!may_be_aliased (alias
))
398 error ("Non-addressable variable inside an alias set.");
399 debug_variable (alias
);
405 for (i
= 0; i
< num_referenced_vars
; i
++)
409 var
= referenced_var (i
);
412 if (ann
->mem_tag_kind
== NOT_A_TAG
414 && !bitmap_bit_p (visited
, ann
->uid
))
416 error ("Addressable variable that is an alias tag but is not in any alias set.");
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
->type_mem_tag
)
468 error ("Dereferenced pointers should have a name or a type tag");
474 && (pi
->pt_vars
== NULL
|| bitmap_empty_p (pi
->pt_vars
)))
476 error ("Pointers with a memory tag, should have points-to sets or point to malloc");
480 if (pi
->value_escapes_p
482 && !is_call_clobbered (pi
->name_mem_tag
))
484 error ("Pointer escapes but its name tag is not call-clobbered.");
492 debug_variable (ptr
);
493 internal_error ("verify_flow_sensitive_alias_info failed.");
496 DEF_VEC_MALLOC_P (bitmap
);
498 /* Verify that all name tags have different points to sets.
499 This algorithm takes advantage of the fact that every variable with the
500 same name tag must have the same points-to set.
501 So we check a single variable for each name tag, and verify that its
502 points-to set is different from every other points-to set for other name
505 Additionally, given a pointer P_i with name tag NMT and type tag
506 TMT, this function verified the alias set of TMT is a superset of
507 the alias set of NMT. */
510 verify_name_tags (void)
514 bitmap first
, second
;
515 VEC (tree
) *name_tag_reps
= NULL
;
516 VEC (bitmap
) *pt_vars_for_reps
= NULL
;
517 bitmap type_aliases
= BITMAP_ALLOC (NULL
);
519 /* First we compute the name tag representatives and their points-to sets. */
520 for (i
= 0; i
< num_ssa_names
; i
++)
522 struct ptr_info_def
*pi
;
523 tree tmt
, ptr
= ssa_name (i
);
525 if (ptr
== NULL_TREE
)
528 pi
= SSA_NAME_PTR_INFO (ptr
);
530 if (!TREE_VISITED (ptr
)
531 || !POINTER_TYPE_P (TREE_TYPE (ptr
))
534 || TREE_VISITED (pi
->name_mem_tag
))
537 TREE_VISITED (pi
->name_mem_tag
) = 1;
539 if (pi
->pt_vars
== NULL
)
542 VEC_safe_push (tree
, name_tag_reps
, ptr
);
543 VEC_safe_push (bitmap
, pt_vars_for_reps
, pi
->pt_vars
);
545 /* Verify that alias set of PTR's type tag is a superset of the
546 alias set of PTR's name tag. */
547 tmt
= var_ann (SSA_NAME_VAR (ptr
))->type_mem_tag
;
551 varray_type aliases
= var_ann (tmt
)->may_aliases
;
552 bitmap_clear (type_aliases
);
553 for (i
= 0; aliases
&& i
< VARRAY_ACTIVE_SIZE (aliases
); i
++)
555 tree alias
= VARRAY_TREE (aliases
, i
);
556 bitmap_set_bit (type_aliases
, var_ann (alias
)->uid
);
559 /* When grouping, we may have added PTR's type tag into the
560 alias set of PTR's name tag. To prevent a false
561 positive, pretend that TMT is in its own alias set. */
562 bitmap_set_bit (type_aliases
, var_ann (tmt
)->uid
);
564 if (bitmap_equal_p (type_aliases
, pi
->pt_vars
))
567 if (!bitmap_intersect_compl_p (type_aliases
, pi
->pt_vars
))
569 error ("Alias set of a pointer's type tag should be a superset of the corresponding name tag");
570 debug_variable (tmt
);
571 debug_variable (pi
->name_mem_tag
);
577 /* Now compare all the representative bitmaps with all other representative
578 bitmaps, to verify that they are all different. */
579 for (i
= 0; VEC_iterate (bitmap
, pt_vars_for_reps
, i
, first
); i
++)
581 for (j
= i
+ 1; VEC_iterate (bitmap
, pt_vars_for_reps
, j
, second
); j
++)
583 if (bitmap_equal_p (first
, second
))
585 error ("Two different pointers with identical points-to sets but different name tags");
586 debug_variable (VEC_index (tree
, name_tag_reps
, j
));
592 /* Lastly, clear out the visited flags. */
593 for (i
= 0; i
< num_ssa_names
; i
++)
597 tree ptr
= ssa_name (i
);
598 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (ptr
);
599 if (!TREE_VISITED (ptr
)
600 || !POINTER_TYPE_P (TREE_TYPE (ptr
))
602 || !pi
->name_mem_tag
)
604 TREE_VISITED (pi
->name_mem_tag
) = 0;
608 VEC_free (bitmap
, pt_vars_for_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 timevar_push (TV_TREE_SSA_VERIFY
);
645 /* Keep track of SSA names present in the IL. */
646 for (i
= 1; i
< num_ssa_names
; i
++)
648 tree name
= ssa_name (i
);
652 TREE_VISITED (name
) = 0;
654 stmt
= SSA_NAME_DEF_STMT (name
);
655 if (!IS_EMPTY_STMT (stmt
))
657 basic_block bb
= bb_for_stmt (stmt
);
658 verify_def (bb
, definition_block
,
659 name
, stmt
, !is_gimple_reg (name
));
665 calculate_dominance_info (CDI_DOMINATORS
);
667 /* Now verify all the uses and make sure they agree with the definitions
668 found in the previous pass. */
674 block_stmt_iterator bsi
;
676 /* Make sure that all edges have a clear 'aux' field. */
677 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
681 error ("AUX pointer initialized for edge %d->%d\n", e
->src
->index
,
687 /* Verify the arguments for every PHI node in the block. */
688 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
690 if (verify_phi_args (phi
, bb
, definition_block
))
692 bitmap_set_bit (names_defined_in_bb
,
693 SSA_NAME_VERSION (PHI_RESULT (phi
)));
696 /* Now verify all the uses and vuses in every statement of the block. */
697 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
699 tree stmt
= bsi_stmt (bsi
);
702 if (check_modified_stmt
&& stmt_modified_p (stmt
))
704 error ("Stmt (0x%x) marked modified after optimization pass : ",
705 (unsigned long)stmt
);
706 print_generic_stmt (stderr
, stmt
, TDF_VOPS
);
710 if (TREE_CODE (stmt
) == MODIFY_EXPR
711 && TREE_CODE (TREE_OPERAND (stmt
, 0)) != SSA_NAME
)
713 tree lhs
, base_address
;
715 lhs
= TREE_OPERAND (stmt
, 0);
716 base_address
= get_base_address (lhs
);
719 && SSA_VAR_P (base_address
)
720 && NUM_V_MAY_DEFS (STMT_V_MAY_DEF_OPS (stmt
)) == 0
721 && NUM_V_MUST_DEFS (STMT_V_MUST_DEF_OPS (stmt
)) == 0)
723 error ("Statement makes a memory store, but has no "
724 "V_MAY_DEFS nor V_MUST_DEFS");
725 print_generic_stmt (stderr
, stmt
, TDF_VOPS
);
731 if (stmt_ann (stmt
)->makes_aliased_stores
732 && NUM_V_MAY_DEFS (STMT_V_MAY_DEF_OPS (stmt
)) == 0)
734 error ("Statement makes aliased stores, but has no V_MAY_DEFS");
735 print_generic_stmt (stderr
, stmt
, TDF_VOPS
);
739 FOR_EACH_SSA_USE_OPERAND (use_p
, stmt
, iter
,
740 SSA_OP_ALL_USES
| SSA_OP_ALL_KILLS
)
742 op
= USE_FROM_PTR (use_p
);
743 if (verify_use (bb
, definition_block
[SSA_NAME_VERSION (op
)],
744 use_p
, stmt
, false, !is_gimple_reg (op
),
745 names_defined_in_bb
))
749 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, iter
, SSA_OP_ALL_DEFS
)
751 bitmap_set_bit (names_defined_in_bb
, SSA_NAME_VERSION (op
));
755 bitmap_clear (names_defined_in_bb
);
758 /* Finally, verify alias information. */
759 verify_alias_info ();
761 free (definition_block
);
762 /* Restore the dominance information to its prior known state, so
763 that we do not perturb the compiler's subsequent behavior. */
764 if (orig_dom_state
== DOM_NONE
)
765 free_dominance_info (CDI_DOMINATORS
);
767 dom_computed
[CDI_DOMINATORS
] = orig_dom_state
;
769 BITMAP_FREE (names_defined_in_bb
);
770 timevar_pop (TV_TREE_SSA_VERIFY
);
774 internal_error ("verify_ssa failed.");
778 /* Initialize global DFA and SSA structures. */
783 VARRAY_TREE_INIT (referenced_vars
, 20, "referenced_vars");
784 call_clobbered_vars
= BITMAP_ALLOC (NULL
);
785 addressable_vars
= BITMAP_ALLOC (NULL
);
788 global_var
= NULL_TREE
;
789 aliases_computed_p
= false;
793 /* Deallocate memory associated with SSA data structures for FNDECL. */
796 delete_tree_ssa (void)
800 block_stmt_iterator bsi
;
802 /* Remove annotations from every tree in the function. */
804 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
806 tree stmt
= bsi_stmt (bsi
);
808 ggc_free (stmt
->common
.ann
);
809 stmt
->common
.ann
= NULL
;
812 /* Remove annotations from every referenced variable. */
815 for (i
= 0; i
< num_referenced_vars
; i
++)
817 tree var
= referenced_var (i
);
818 ggc_free (var
->common
.ann
);
819 var
->common
.ann
= NULL
;
821 referenced_vars
= NULL
;
827 global_var
= NULL_TREE
;
828 BITMAP_FREE (call_clobbered_vars
);
829 call_clobbered_vars
= NULL
;
830 BITMAP_FREE (addressable_vars
);
831 addressable_vars
= NULL
;
832 modified_noreturn_calls
= NULL
;
833 aliases_computed_p
= false;
837 /* Return true if EXPR is a useless type conversion, otherwise return
841 tree_ssa_useless_type_conversion_1 (tree outer_type
, tree inner_type
)
843 if (inner_type
== outer_type
)
846 /* Changes in machine mode are never useless conversions. */
847 if (TYPE_MODE (inner_type
) != TYPE_MODE (outer_type
))
850 /* If the inner and outer types are effectively the same, then
851 strip the type conversion and enter the equivalence into
853 if (lang_hooks
.types_compatible_p (inner_type
, outer_type
))
856 /* If both types are pointers and the outer type is a (void *), then
857 the conversion is not necessary. The opposite is not true since
858 that conversion would result in a loss of information if the
859 equivalence was used. Consider an indirect function call where
860 we need to know the exact type of the function to correctly
861 implement the ABI. */
862 else if (POINTER_TYPE_P (inner_type
)
863 && POINTER_TYPE_P (outer_type
)
864 && TYPE_REF_CAN_ALIAS_ALL (inner_type
)
865 == TYPE_REF_CAN_ALIAS_ALL (outer_type
)
866 && TREE_CODE (TREE_TYPE (outer_type
)) == VOID_TYPE
)
869 /* Pointers and references are equivalent once we get to GENERIC,
870 so strip conversions that just switch between them. */
871 else if (POINTER_TYPE_P (inner_type
)
872 && POINTER_TYPE_P (outer_type
)
873 && TYPE_REF_CAN_ALIAS_ALL (inner_type
)
874 == TYPE_REF_CAN_ALIAS_ALL (outer_type
)
875 && lang_hooks
.types_compatible_p (TREE_TYPE (inner_type
),
876 TREE_TYPE (outer_type
)))
879 /* If both the inner and outer types are integral types, then the
880 conversion is not necessary if they have the same mode and
881 signedness and precision, and both or neither are boolean. Some
882 code assumes an invariant that boolean types stay boolean and do
883 not become 1-bit bit-field types. Note that types with precision
884 not using all bits of the mode (such as bit-field types in C)
885 mean that testing of precision is necessary. */
886 else if (INTEGRAL_TYPE_P (inner_type
)
887 && INTEGRAL_TYPE_P (outer_type
)
888 && TYPE_UNSIGNED (inner_type
) == TYPE_UNSIGNED (outer_type
)
889 && TYPE_PRECISION (inner_type
) == TYPE_PRECISION (outer_type
))
891 bool first_boolean
= (TREE_CODE (inner_type
) == BOOLEAN_TYPE
);
892 bool second_boolean
= (TREE_CODE (outer_type
) == BOOLEAN_TYPE
);
893 if (first_boolean
== second_boolean
)
897 /* Recurse for complex types. */
898 else if (TREE_CODE (inner_type
) == COMPLEX_TYPE
899 && TREE_CODE (outer_type
) == COMPLEX_TYPE
900 && tree_ssa_useless_type_conversion_1 (TREE_TYPE (outer_type
),
901 TREE_TYPE (inner_type
)))
907 /* Return true if EXPR is a useless type conversion, otherwise return
911 tree_ssa_useless_type_conversion (tree expr
)
913 /* If we have an assignment that merely uses a NOP_EXPR to change
914 the top of the RHS to the type of the LHS and the type conversion
915 is "safe", then strip away the type conversion so that we can
916 enter LHS = RHS into the const_and_copies table. */
917 if (TREE_CODE (expr
) == NOP_EXPR
|| TREE_CODE (expr
) == CONVERT_EXPR
918 || TREE_CODE (expr
) == VIEW_CONVERT_EXPR
919 || TREE_CODE (expr
) == NON_LVALUE_EXPR
)
920 return tree_ssa_useless_type_conversion_1 (TREE_TYPE (expr
),
921 TREE_TYPE (TREE_OPERAND (expr
,
928 /* Returns true if statement STMT may read memory. */
931 stmt_references_memory_p (tree stmt
)
935 get_stmt_operands (stmt
);
936 ann
= stmt_ann (stmt
);
938 if (ann
->has_volatile_ops
)
941 return (NUM_VUSES (VUSE_OPS (ann
)) > 0
942 || NUM_V_MAY_DEFS (V_MAY_DEF_OPS (ann
)) > 0
943 || NUM_V_MUST_DEFS (V_MUST_DEF_OPS (ann
)) > 0);
946 /* Internal helper for walk_use_def_chains. VAR, FN and DATA are as
947 described in walk_use_def_chains.
949 VISITED is a pointer set used to mark visited SSA_NAMEs to avoid
950 infinite loops. We used to have a bitmap for this to just mark
951 SSA versions we had visited. But non-sparse bitmaps are way too
952 expensive, while sparse bitmaps may cause quadratic behavior.
954 IS_DFS is true if the caller wants to perform a depth-first search
955 when visiting PHI nodes. A DFS will visit each PHI argument and
956 call FN after each one. Otherwise, all the arguments are
957 visited first and then FN is called with each of the visited
958 arguments in a separate pass. */
961 walk_use_def_chains_1 (tree var
, walk_use_def_chains_fn fn
, void *data
,
962 struct pointer_set_t
*visited
, bool is_dfs
)
966 if (pointer_set_insert (visited
, var
))
969 def_stmt
= SSA_NAME_DEF_STMT (var
);
971 if (TREE_CODE (def_stmt
) != PHI_NODE
)
973 /* If we reached the end of the use-def chain, call FN. */
974 return fn (var
, def_stmt
, data
);
980 /* When doing a breadth-first search, call FN before following the
981 use-def links for each argument. */
983 for (i
= 0; i
< PHI_NUM_ARGS (def_stmt
); i
++)
984 if (fn (PHI_ARG_DEF (def_stmt
, i
), def_stmt
, data
))
987 /* Follow use-def links out of each PHI argument. */
988 for (i
= 0; i
< PHI_NUM_ARGS (def_stmt
); i
++)
990 tree arg
= PHI_ARG_DEF (def_stmt
, i
);
991 if (TREE_CODE (arg
) == SSA_NAME
992 && walk_use_def_chains_1 (arg
, fn
, data
, visited
, is_dfs
))
996 /* When doing a depth-first search, call FN after following the
997 use-def links for each argument. */
999 for (i
= 0; i
< PHI_NUM_ARGS (def_stmt
); i
++)
1000 if (fn (PHI_ARG_DEF (def_stmt
, i
), def_stmt
, data
))
1009 /* Walk use-def chains starting at the SSA variable VAR. Call
1010 function FN at each reaching definition found. FN takes three
1011 arguments: VAR, its defining statement (DEF_STMT) and a generic
1012 pointer to whatever state information that FN may want to maintain
1013 (DATA). FN is able to stop the walk by returning true, otherwise
1014 in order to continue the walk, FN should return false.
1016 Note, that if DEF_STMT is a PHI node, the semantics are slightly
1017 different. The first argument to FN is no longer the original
1018 variable VAR, but the PHI argument currently being examined. If FN
1019 wants to get at VAR, it should call PHI_RESULT (PHI).
1021 If IS_DFS is true, this function will:
1023 1- walk the use-def chains for all the PHI arguments, and,
1024 2- call (*FN) (ARG, PHI, DATA) on all the PHI arguments.
1026 If IS_DFS is false, the two steps above are done in reverse order
1027 (i.e., a breadth-first search). */
1031 walk_use_def_chains (tree var
, walk_use_def_chains_fn fn
, void *data
,
1036 gcc_assert (TREE_CODE (var
) == SSA_NAME
);
1038 def_stmt
= SSA_NAME_DEF_STMT (var
);
1040 /* We only need to recurse if the reaching definition comes from a PHI
1042 if (TREE_CODE (def_stmt
) != PHI_NODE
)
1043 (*fn
) (var
, def_stmt
, data
);
1046 struct pointer_set_t
*visited
= pointer_set_create ();
1047 walk_use_def_chains_1 (var
, fn
, data
, visited
, is_dfs
);
1048 pointer_set_destroy (visited
);
1053 /* Emit warnings for uninitialized variables. This is done in two passes.
1055 The first pass notices real uses of SSA names with default definitions.
1056 Such uses are unconditionally uninitialized, and we can be certain that
1057 such a use is a mistake. This pass is run before most optimizations,
1058 so that we catch as many as we can.
1060 The second pass follows PHI nodes to find uses that are potentially
1061 uninitialized. In this case we can't necessarily prove that the use
1062 is really uninitialized. This pass is run after most optimizations,
1063 so that we thread as many jumps and possible, and delete as much dead
1064 code as possible, in order to reduce false positives. We also look
1065 again for plain uninitialized variables, since optimization may have
1066 changed conditionally uninitialized to unconditionally uninitialized. */
1068 /* Emit a warning for T, an SSA_NAME, being uninitialized. The exact
1069 warning text is in MSGID and LOCUS may contain a location or be null. */
1072 warn_uninit (tree t
, const char *msgid
, void *data
)
1074 tree var
= SSA_NAME_VAR (t
);
1075 tree def
= SSA_NAME_DEF_STMT (t
);
1076 tree context
= (tree
) data
;
1079 /* Default uses (indicated by an empty definition statement),
1080 are uninitialized. */
1081 if (!IS_EMPTY_STMT (def
))
1084 /* Except for PARMs of course, which are always initialized. */
1085 if (TREE_CODE (var
) == PARM_DECL
)
1088 /* Hard register variables get their initial value from the ether. */
1089 if (TREE_CODE (var
) == VAR_DECL
&& DECL_HARD_REGISTER (var
))
1092 /* TREE_NO_WARNING either means we already warned, or the front end
1093 wishes to suppress the warning. */
1094 if (TREE_NO_WARNING (var
))
1097 locus
= (context
!= NULL
&& EXPR_HAS_LOCATION (context
)
1098 ? EXPR_LOCUS (context
)
1099 : &DECL_SOURCE_LOCATION (var
));
1100 warning (msgid
, locus
, var
);
1101 TREE_NO_WARNING (var
) = 1;
1104 /* Called via walk_tree, look for SSA_NAMEs that have empty definitions
1105 and warn about them. */
1108 warn_uninitialized_var (tree
*tp
, int *walk_subtrees
, void *data
)
1112 /* We only do data flow with SSA_NAMEs, so that's all we can warn about. */
1113 if (TREE_CODE (t
) == SSA_NAME
)
1115 warn_uninit (t
, "%H%qD is used uninitialized in this function", data
);
1118 else if (IS_TYPE_OR_DECL_P (t
))
1124 /* Look for inputs to PHI that are SSA_NAMEs that have empty definitions
1125 and warn about them. */
1128 warn_uninitialized_phi (tree phi
)
1130 int i
, n
= PHI_NUM_ARGS (phi
);
1132 /* Don't look at memory tags. */
1133 if (!is_gimple_reg (PHI_RESULT (phi
)))
1136 for (i
= 0; i
< n
; ++i
)
1138 tree op
= PHI_ARG_DEF (phi
, i
);
1139 if (TREE_CODE (op
) == SSA_NAME
)
1140 warn_uninit (op
, "%H%qD may be used uninitialized in this function",
1146 execute_early_warn_uninitialized (void)
1148 block_stmt_iterator bsi
;
1152 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1154 tree context
= bsi_stmt (bsi
);
1155 walk_tree (bsi_stmt_ptr (bsi
), warn_uninitialized_var
,
1161 execute_late_warn_uninitialized (void)
1166 /* Re-do the plain uninitialized variable check, as optimization may have
1167 straightened control flow. Do this first so that we don't accidentally
1168 get a "may be" warning when we'd have seen an "is" warning later. */
1169 execute_early_warn_uninitialized ();
1172 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
1173 warn_uninitialized_phi (phi
);
1177 gate_warn_uninitialized (void)
1179 return warn_uninitialized
!= 0;
1182 struct tree_opt_pass pass_early_warn_uninitialized
=
1185 gate_warn_uninitialized
, /* gate */
1186 execute_early_warn_uninitialized
, /* execute */
1189 0, /* static_pass_number */
1191 PROP_ssa
, /* properties_required */
1192 0, /* properties_provided */
1193 0, /* properties_destroyed */
1194 0, /* todo_flags_start */
1195 0, /* todo_flags_finish */
1199 struct tree_opt_pass pass_late_warn_uninitialized
=
1202 gate_warn_uninitialized
, /* gate */
1203 execute_late_warn_uninitialized
, /* execute */
1206 0, /* static_pass_number */
1208 PROP_ssa
, /* properties_required */
1209 0, /* properties_provided */
1210 0, /* properties_destroyed */
1211 0, /* todo_flags_start */
1212 0, /* todo_flags_finish */