1 /* Basic IPA utilities for type inheritance graph construction and
3 Copyright (C) 2013-2014 Free Software Foundation, Inc.
4 Contributed by Jan Hubicka
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
23 ODR = One Definition Rule
24 In short, the ODR states that:
25 1 In any translation unit, a template, type, function, or object can
26 have no more than one definition. Some of these can have any number
27 of declarations. A definition provides an instance.
28 2 In the entire program, an object or non-inline function cannot have
29 more than one definition; if an object or function is used, it must
30 have exactly one definition. You can declare an object or function
31 that is never used, in which case you don't have to provide
32 a definition. In no event can there be more than one definition.
33 3 Some things, like types, templates, and extern inline functions, can
34 be defined in more than one translation unit. For a given entity,
35 each definition must be the same. Non-extern objects and functions
36 in different translation units are different entities, even if their
37 names and types are the same.
40 This is the Gimple representation of type information of a polymorphic call.
41 It contains two parameters:
42 otr_type is a type of class whose method is called.
43 otr_token is the index into virtual table where address is taken.
46 This is the type inheritance information attached to each tree
47 RECORD_TYPE by the C++ frotend. It provides information about base
48 types and virtual tables.
50 BINFO is linked to the RECORD_TYPE by TYPE_BINFO.
51 BINFO also links to its type by BINFO_TYPE and to the virtual table by
54 Base types of a given type are enumerated by BINFO_BASE_BINFO
55 vector. Members of this vectors are not BINFOs associated
56 with a base type. Rather they are new copies of BINFOs
57 (base BINFOs). Their virtual tables may differ from
58 virtual table of the base type. Also BINFO_OFFSET specifies
59 offset of the base within the type.
61 In the case of single inheritance, the virtual table is shared
62 and BINFO_VTABLE of base BINFO is NULL. In the case of multiple
63 inheritance the individual virtual tables are pointer to by
64 BINFO_VTABLE of base binfos (that differs of BINFO_VTABLE of
65 binfo associated to the base type).
67 BINFO lookup for a given base type and offset can be done by
68 get_binfo_at_offset. It returns proper BINFO whose virtual table
69 can be used for lookup of virtual methods associated with the
73 This is an index of virtual method in virtual table associated
74 to the type defining it. Token can be looked up from OBJ_TYPE_REF
75 or from DECL_VINDEX of a given virtual table.
77 polymorphic (indirect) call
78 This is callgraph represention of virtual method call. Every
79 polymorphic call contains otr_type and otr_token taken from
80 original OBJ_TYPE_REF at callgraph construction time.
84 build_type_inheritance_graph triggers a construction of the type inheritance
87 We reconstruct it based on types of methods we see in the unit.
88 This means that the graph is not complete. Types with no methods are not
89 inserted into the graph. Also types without virtual methods are not
90 represented at all, though it may be easy to add this.
92 The inheritance graph is represented as follows:
94 Vertices are structures odr_type. Every odr_type may correspond
95 to one or more tree type nodes that are equivalent by ODR rule.
96 (the multiple type nodes appear only with linktime optimization)
98 Edges are represented by odr_type->base and odr_type->derived_types.
99 At the moment we do not track offsets of types for multiple inheritance.
102 possible_polymorphic_call_targets returns, given an parameters found in
103 indirect polymorphic edge all possible polymorphic call targets of the call.
105 pass_ipa_devirt performs simple speculative devirtualization.
110 #include "coretypes.h"
113 #include "print-tree.h"
117 #include "tree-pass.h"
118 #include "pointer-set.h"
120 #include "hash-table.h"
121 #include "tree-pretty-print.h"
122 #include "ipa-utils.h"
123 #include "tree-ssa-alias.h"
124 #include "internal-fn.h"
125 #include "gimple-fold.h"
126 #include "gimple-expr.h"
128 #include "ipa-inline.h"
129 #include "diagnostic.h"
130 #include "tree-dfa.h"
131 #include "demangle.h"
134 static bool odr_violation_reported
= false;
136 /* Dummy polymorphic call context. */
138 const ipa_polymorphic_call_context ipa_dummy_polymorphic_call_context
139 = {0, NULL
, false, true};
141 /* Pointer set of all call targets appearing in the cache. */
142 static pointer_set_t
*cached_polymorphic_call_targets
;
144 /* The node of type inheritance graph. For each type unique in
145 One Defintion Rule (ODR) sense, we produce one node linking all
146 main variants of types equivalent to it, bases and derived types. */
148 struct GTY(()) odr_type_d
153 vec
<odr_type
> GTY((skip
)) bases
;
154 /* All derrived types with virtual methods seen in unit. */
155 vec
<odr_type
> GTY((skip
)) derived_types
;
157 /* All equivalent types, if more than one. */
158 vec
<tree
, va_gc
> *types
;
159 /* Set of all equivalent types, if NON-NULL. */
160 pointer_set_t
* GTY((skip
)) types_set
;
162 /* Unique ID indexing the type in odr_types array. */
164 /* Is it in anonymous namespace? */
165 bool anonymous_namespace
;
166 /* Do we know about all derivations of given type? */
167 bool all_derivations_known
;
171 /* Return true if BINFO corresponds to a type with virtual methods.
173 Every type has several BINFOs. One is the BINFO associated by the type
174 while other represents bases of derived types. The BINFOs representing
175 bases do not have BINFO_VTABLE pointer set when this is the single
176 inheritance (because vtables are shared). Look up the BINFO of type
177 and check presence of its vtable. */
180 polymorphic_type_binfo_p (tree binfo
)
182 /* See if BINFO's type has an virtual table associtated with it. */
183 return BINFO_VTABLE (TYPE_BINFO (BINFO_TYPE (binfo
)));
186 /* Return TRUE if all derived types of T are known and thus
187 we may consider the walk of derived type complete.
189 This is typically true only for final anonymous namespace types and types
190 defined within functions (that may be COMDAT and thus shared across units,
191 but with the same set of derived types). */
194 type_all_derivations_known_p (tree t
)
196 if (TYPE_FINAL_P (t
))
200 if (type_in_anonymous_namespace_p (t
))
202 return (decl_function_context (TYPE_NAME (t
)) != NULL
);
205 /* Return TURE if type's constructors are all visible. */
208 type_all_ctors_visible_p (tree t
)
211 && cgraph_state
>= CGRAPH_STATE_CONSTRUCTION
212 /* We can not always use type_all_derivations_known_p.
213 For function local types we must assume case where
214 the function is COMDAT and shared in between units.
216 TODO: These cases are quite easy to get, but we need
217 to keep track of C++ privatizing via -Wno-weak
218 as well as the IPA privatizing. */
219 && type_in_anonymous_namespace_p (t
);
222 /* Return TRUE if type may have instance. */
225 type_possibly_instantiated_p (tree t
)
230 /* TODO: Add abstract types here. */
231 if (!type_all_ctors_visible_p (t
))
234 vtable
= BINFO_VTABLE (TYPE_BINFO (t
));
235 if (TREE_CODE (vtable
) == POINTER_PLUS_EXPR
)
236 vtable
= TREE_OPERAND (TREE_OPERAND (vtable
, 0), 0);
237 vnode
= varpool_get_node (vtable
);
238 return vnode
&& vnode
->definition
;
241 /* One Definition Rule hashtable helpers. */
245 typedef odr_type_d value_type
;
246 typedef union tree_node compare_type
;
247 static inline hashval_t
hash (const value_type
*);
248 static inline bool equal (const value_type
*, const compare_type
*);
249 static inline void remove (value_type
*);
252 /* Produce hash based on type name. */
255 hash_type_name (tree t
)
257 gcc_checking_assert (TYPE_MAIN_VARIANT (t
) == t
);
259 /* If not in LTO, all main variants are unique, so we can do
262 return htab_hash_pointer (t
);
264 /* Anonymous types are unique. */
265 if (type_in_anonymous_namespace_p (t
))
266 return htab_hash_pointer (t
);
268 /* For polymorphic types, we can simply hash the virtual table. */
269 if (TYPE_BINFO (t
) && BINFO_VTABLE (TYPE_BINFO (t
)))
271 tree v
= BINFO_VTABLE (TYPE_BINFO (t
));
274 if (TREE_CODE (v
) == POINTER_PLUS_EXPR
)
276 hash
= TREE_INT_CST_LOW (TREE_OPERAND (v
, 1));
277 v
= TREE_OPERAND (TREE_OPERAND (v
, 0), 0);
280 v
= DECL_ASSEMBLER_NAME (v
);
281 hash
= iterative_hash_hashval_t (hash
, htab_hash_pointer (v
));
285 /* Rest is not implemented yet. */
289 /* Return the computed hashcode for ODR_TYPE. */
292 odr_hasher::hash (const value_type
*odr_type
)
294 return hash_type_name (odr_type
->type
);
297 /* Compare types T1 and T2 and return true if they are
301 odr_hasher::equal (const value_type
*t1
, const compare_type
*ct2
)
303 tree t2
= const_cast <tree
> (ct2
);
305 gcc_checking_assert (TYPE_MAIN_VARIANT (ct2
) == ct2
);
310 return types_same_for_odr (t1
->type
, t2
);
313 /* Free ODR type V. */
316 odr_hasher::remove (value_type
*v
)
319 v
->derived_types
.release ();
321 pointer_set_destroy (v
->types_set
);
325 /* ODR type hash used to lookup ODR type based on tree type node. */
327 typedef hash_table
<odr_hasher
> odr_hash_type
;
328 static odr_hash_type
*odr_hash
;
330 /* ODR types are also stored into ODR_TYPE vector to allow consistent
331 walking. Bases appear before derived types. Vector is garbage collected
332 so we won't end up visiting empty types. */
334 static GTY(()) vec
<odr_type
, va_gc
> *odr_types_ptr
;
335 #define odr_types (*odr_types_ptr)
337 /* TYPE is equivalent to VAL by ODR, but its tree representation differs
338 from VAL->type. This may happen in LTO where tree merging did not merge
339 all variants of the same type. It may or may not mean the ODR violation.
340 Add it to the list of duplicates and warn on some violations. */
343 add_type_duplicate (odr_type val
, tree type
)
346 val
->types_set
= pointer_set_create ();
348 /* See if this duplicate is new. */
349 if (!pointer_set_insert (val
->types_set
, type
))
352 bool base_mismatch
= false;
353 gcc_assert (in_lto_p
);
354 vec_safe_push (val
->types
, type
);
357 /* First we compare memory layout. */
358 if (!types_compatible_p (val
->type
, type
))
361 odr_violation_reported
= true;
362 if (BINFO_VTABLE (TYPE_BINFO (val
->type
))
363 && warning_at (DECL_SOURCE_LOCATION (TYPE_NAME (type
)), 0,
364 "type %qD violates one definition rule ",
366 inform (DECL_SOURCE_LOCATION (TYPE_NAME (val
->type
)),
367 "a type with the same name but different layout is "
368 "defined in another translation unit");
369 if (cgraph_dump_file
)
371 fprintf (cgraph_dump_file
, "ODR violation or merging or ODR type bug?\n");
373 print_node (cgraph_dump_file
, "", val
->type
, 0);
374 putc ('\n',cgraph_dump_file
);
375 print_node (cgraph_dump_file
, "", type
, 0);
376 putc ('\n',cgraph_dump_file
);
380 /* Next sanity check that bases are the same. If not, we will end
381 up producing wrong answers. */
382 for (j
= 0, i
= 0; i
< BINFO_N_BASE_BINFOS (TYPE_BINFO (type
)); i
++)
383 if (polymorphic_type_binfo_p (BINFO_BASE_BINFO (TYPE_BINFO (type
), i
)))
385 odr_type base
= get_odr_type
387 (BINFO_BASE_BINFO (TYPE_BINFO (type
),
390 if (val
->bases
.length () <= j
|| val
->bases
[j
] != base
)
391 base_mismatch
= true;
397 odr_violation_reported
= true;
399 if (warning_at (DECL_SOURCE_LOCATION (TYPE_NAME (type
)), 0,
400 "type %qD violates one definition rule ",
402 inform (DECL_SOURCE_LOCATION (TYPE_NAME (val
->type
)),
403 "a type with the same name but different bases is "
404 "defined in another translation unit");
405 if (cgraph_dump_file
)
407 fprintf (cgraph_dump_file
, "ODR bse violation or merging bug?\n");
409 print_node (cgraph_dump_file
, "", val
->type
, 0);
410 putc ('\n',cgraph_dump_file
);
411 print_node (cgraph_dump_file
, "", type
, 0);
412 putc ('\n',cgraph_dump_file
);
416 /* Regularize things a little. During LTO same types may come with
417 different BINFOs. Either because their virtual table was
418 not merged by tree merging and only later at decl merging or
419 because one type comes with external vtable, while other
420 with internal. We want to merge equivalent binfos to conserve
421 memory and streaming overhead.
423 The external vtables are more harmful: they contain references
424 to external declarations of methods that may be defined in the
425 merged LTO unit. For this reason we absolutely need to remove
426 them and replace by internal variants. Not doing so will lead
427 to incomplete answers from possible_polymorphic_call_targets. */
428 if (!flag_ltrans
&& merge
)
430 tree master_binfo
= TYPE_BINFO (val
->type
);
431 tree v1
= BINFO_VTABLE (master_binfo
);
432 tree v2
= BINFO_VTABLE (TYPE_BINFO (type
));
434 if (TREE_CODE (v1
) == POINTER_PLUS_EXPR
)
436 gcc_assert (TREE_CODE (v2
) == POINTER_PLUS_EXPR
437 && operand_equal_p (TREE_OPERAND (v1
, 1),
438 TREE_OPERAND (v2
, 1), 0));
439 v1
= TREE_OPERAND (TREE_OPERAND (v1
, 0), 0);
440 v2
= TREE_OPERAND (TREE_OPERAND (v2
, 0), 0);
442 gcc_assert (DECL_ASSEMBLER_NAME (v1
)
443 == DECL_ASSEMBLER_NAME (v2
));
445 if (DECL_EXTERNAL (v1
) && !DECL_EXTERNAL (v2
))
449 TYPE_BINFO (val
->type
) = TYPE_BINFO (type
);
450 for (i
= 0; i
< val
->types
->length (); i
++)
452 if (TYPE_BINFO ((*val
->types
)[i
])
454 TYPE_BINFO ((*val
->types
)[i
]) = TYPE_BINFO (type
);
458 TYPE_BINFO (type
) = master_binfo
;
463 /* Get ODR type hash entry for TYPE. If INSERT is true, create
464 possibly new entry. */
467 get_odr_type (tree type
, bool insert
)
473 type
= TYPE_MAIN_VARIANT (type
);
474 gcc_checking_assert (TYPE_MAIN_VARIANT (type
) == type
);
475 hash
= hash_type_name (type
);
477 = odr_hash
->find_slot_with_hash (type
, hash
, insert
? INSERT
: NO_INSERT
);
481 /* See if we already have entry for type. */
486 /* With LTO we need to support multiple tree representation of
487 the same ODR type. */
488 if (val
->type
!= type
)
489 add_type_duplicate (val
, type
);
493 tree binfo
= TYPE_BINFO (type
);
496 val
= ggc_cleared_alloc
<odr_type_d
> ();
499 val
->derived_types
= vNULL
;
500 val
->anonymous_namespace
= type_in_anonymous_namespace_p (type
);
501 val
->all_derivations_known
= type_all_derivations_known_p (type
);
503 for (i
= 0; i
< BINFO_N_BASE_BINFOS (binfo
); i
++)
504 /* For now record only polymorphic types. other are
505 pointless for devirtualization and we can not precisely
506 determine ODR equivalency of these during LTO. */
507 if (polymorphic_type_binfo_p (BINFO_BASE_BINFO (binfo
, i
)))
509 odr_type base
= get_odr_type (BINFO_TYPE (BINFO_BASE_BINFO (binfo
,
512 base
->derived_types
.safe_push (val
);
513 val
->bases
.safe_push (base
);
515 /* First record bases, then add into array so ids are increasing. */
517 val
->id
= odr_types
.length ();
518 vec_safe_push (odr_types_ptr
, val
);
523 /* Dump ODR type T and all its derrived type. INDENT specify indentation for
524 recusive printing. */
527 dump_odr_type (FILE *f
, odr_type t
, int indent
=0)
530 fprintf (f
, "%*s type %i: ", indent
* 2, "", t
->id
);
531 print_generic_expr (f
, t
->type
, TDF_SLIM
);
532 fprintf (f
, "%s", t
->anonymous_namespace
? " (anonymous namespace)":"");
533 fprintf (f
, "%s\n", t
->all_derivations_known
? " (derivations known)":"");
534 if (TYPE_NAME (t
->type
))
536 fprintf (f
, "%*s defined at: %s:%i\n", indent
* 2, "",
537 DECL_SOURCE_FILE (TYPE_NAME (t
->type
)),
538 DECL_SOURCE_LINE (TYPE_NAME (t
->type
)));
540 if (t
->bases
.length ())
542 fprintf (f
, "%*s base odr type ids: ", indent
* 2, "");
543 for (i
= 0; i
< t
->bases
.length (); i
++)
544 fprintf (f
, " %i", t
->bases
[i
]->id
);
547 if (t
->derived_types
.length ())
549 fprintf (f
, "%*s derived types:\n", indent
* 2, "");
550 for (i
= 0; i
< t
->derived_types
.length (); i
++)
551 dump_odr_type (f
, t
->derived_types
[i
], indent
+ 1);
556 /* Dump the type inheritance graph. */
559 dump_type_inheritance_graph (FILE *f
)
564 fprintf (f
, "\n\nType inheritance graph:\n");
565 for (i
= 0; i
< odr_types
.length (); i
++)
567 if (odr_types
[i
]->bases
.length () == 0)
568 dump_odr_type (f
, odr_types
[i
]);
570 for (i
= 0; i
< odr_types
.length (); i
++)
572 if (odr_types
[i
]->types
&& odr_types
[i
]->types
->length ())
575 fprintf (f
, "Duplicate tree types for odr type %i\n", i
);
576 print_node (f
, "", odr_types
[i
]->type
, 0);
577 for (j
= 0; j
< odr_types
[i
]->types
->length (); j
++)
580 fprintf (f
, "duplicate #%i\n", j
);
581 print_node (f
, "", (*odr_types
[i
]->types
)[j
], 0);
582 t
= (*odr_types
[i
]->types
)[j
];
583 while (TYPE_P (t
) && TYPE_CONTEXT (t
))
585 t
= TYPE_CONTEXT (t
);
586 print_node (f
, "", t
, 0);
594 /* Given method type T, return type of class it belongs to.
595 Lookup this pointer and get its type. */
598 method_class_type (tree t
)
600 tree first_parm_type
= TREE_VALUE (TYPE_ARG_TYPES (t
));
601 gcc_assert (TREE_CODE (t
) == METHOD_TYPE
);
603 return TREE_TYPE (first_parm_type
);
606 /* Initialize IPA devirt and build inheritance tree graph. */
609 build_type_inheritance_graph (void)
611 struct symtab_node
*n
;
612 FILE *inheritance_dump_file
;
617 timevar_push (TV_IPA_INHERITANCE
);
618 inheritance_dump_file
= dump_begin (TDI_inheritance
, &flags
);
619 odr_hash
= new odr_hash_type (23);
621 /* We reconstruct the graph starting of types of all methods seen in the
624 if (is_a
<cgraph_node
*> (n
)
625 && DECL_VIRTUAL_P (n
->decl
)
626 && symtab_real_symbol_p (n
))
627 get_odr_type (method_class_type (TREE_TYPE (n
->decl
)), true);
629 /* Look also for virtual tables of types that do not define any methods.
631 We need it in a case where class B has virtual base of class A
632 re-defining its virtual method and there is class C with no virtual
633 methods with B as virtual base.
635 Here we output B's virtual method in two variant - for non-virtual
636 and virtual inheritance. B's virtual table has non-virtual version,
637 while C's has virtual.
639 For this reason we need to know about C in order to include both
640 variants of B. More correctly, record_target_from_binfo should
641 add both variants of the method when walking B, but we have no
642 link in between them.
644 We rely on fact that either the method is exported and thus we
645 assume it is called externally or C is in anonymous namespace and
646 thus we will see the vtable. */
648 else if (is_a
<varpool_node
*> (n
)
649 && DECL_VIRTUAL_P (n
->decl
)
650 && TREE_CODE (DECL_CONTEXT (n
->decl
)) == RECORD_TYPE
651 && TYPE_BINFO (DECL_CONTEXT (n
->decl
))
652 && polymorphic_type_binfo_p (TYPE_BINFO (DECL_CONTEXT (n
->decl
))))
653 get_odr_type (DECL_CONTEXT (n
->decl
), true);
654 if (inheritance_dump_file
)
656 dump_type_inheritance_graph (inheritance_dump_file
);
657 dump_end (TDI_inheritance
, inheritance_dump_file
);
659 timevar_pop (TV_IPA_INHERITANCE
);
662 /* Return true if N has reference from live virtual table
663 (and thus can be a destination of polymorphic call).
664 Be conservatively correct when callgraph is not built or
665 if the method may be referred externally. */
668 referenced_from_vtable_p (struct cgraph_node
*node
)
674 if (node
->externally_visible
675 || node
->used_from_other_partition
)
678 /* Keep this test constant time.
679 It is unlikely this can happen except for the case where speculative
680 devirtualization introduced many speculative edges to this node.
681 In this case the target is very likely alive anyway. */
682 if (node
->ref_list
.referring
.length () > 100)
685 /* We need references built. */
686 if (cgraph_state
<= CGRAPH_STATE_CONSTRUCTION
)
689 for (i
= 0; node
->iterate_referring (i
, ref
); i
++)
691 if ((ref
->use
== IPA_REF_ALIAS
692 && referenced_from_vtable_p (cgraph (ref
->referring
)))
693 || (ref
->use
== IPA_REF_ADDR
694 && TREE_CODE (ref
->referring
->decl
) == VAR_DECL
695 && DECL_VIRTUAL_P (ref
->referring
->decl
)))
703 /* If TARGET has associated node, record it in the NODES array.
704 CAN_REFER specify if program can refer to the target directly.
705 if TARGET is unknown (NULL) or it can not be inserted (for example because
706 its body was already removed and there is no way to refer to it), clear
710 maybe_record_node (vec
<cgraph_node
*> &nodes
,
711 tree target
, pointer_set_t
*inserted
,
715 struct cgraph_node
*target_node
;
717 /* cxa_pure_virtual and __builtin_unreachable do not need to be added into
718 list of targets; the runtime effect of calling them is undefined.
719 Only "real" virtual methods should be accounted. */
720 if (target
&& TREE_CODE (TREE_TYPE (target
)) != METHOD_TYPE
)
725 /* The only case when method of anonymous namespace becomes unreferable
726 is when we completely optimized it out. */
729 || !type_in_anonymous_namespace_p (DECL_CONTEXT (target
)))
737 target_node
= cgraph_get_node (target
);
739 /* Method can only be called by polymorphic call if any
740 of vtables refering to it are alive.
742 While this holds for non-anonymous functions, too, there are
743 cases where we want to keep them in the list; for example
744 inline functions with -fno-weak are static, but we still
745 may devirtualize them when instance comes from other unit.
746 The same holds for LTO.
748 Currently we ignore these functions in speculative devirtualization.
749 ??? Maybe it would make sense to be more aggressive for LTO even
752 && type_in_anonymous_namespace_p (DECL_CONTEXT (target
))
754 || !referenced_from_vtable_p (target_node
)))
756 /* See if TARGET is useful function we can deal with. */
757 else if (target_node
!= NULL
758 && (TREE_PUBLIC (target
)
759 || DECL_EXTERNAL (target
)
760 || target_node
->definition
)
761 && symtab_real_symbol_p (target_node
))
763 gcc_assert (!target_node
->global
.inlined_to
);
764 gcc_assert (symtab_real_symbol_p (target_node
));
765 if (!pointer_set_insert (inserted
, target
))
767 pointer_set_insert (cached_polymorphic_call_targets
,
769 nodes
.safe_push (target_node
);
773 && (!type_in_anonymous_namespace_p
774 (DECL_CONTEXT (target
))
779 /* See if BINFO's type match OUTER_TYPE. If so, lookup
780 BINFO of subtype of OTR_TYPE at OFFSET and in that BINFO find
781 method in vtable and insert method to NODES array
782 or BASES_TO_CONSIDER if this array is non-NULL.
783 Otherwise recurse to base BINFOs.
784 This match what get_binfo_at_offset does, but with offset
787 TYPE_BINFOS is a stack of BINFOS of types with defined
788 virtual table seen on way from class type to BINFO.
790 MATCHED_VTABLES tracks virtual tables we already did lookup
791 for virtual function in. INSERTED tracks nodes we already
794 ANONYMOUS is true if BINFO is part of anonymous namespace.
796 Clear COMPLETEP when we hit unreferable target.
800 record_target_from_binfo (vec
<cgraph_node
*> &nodes
,
801 vec
<tree
> *bases_to_consider
,
804 vec
<tree
> &type_binfos
,
805 HOST_WIDE_INT otr_token
,
807 HOST_WIDE_INT offset
,
808 pointer_set_t
*inserted
,
809 pointer_set_t
*matched_vtables
,
813 tree type
= BINFO_TYPE (binfo
);
818 if (BINFO_VTABLE (binfo
))
819 type_binfos
.safe_push (binfo
);
820 if (types_same_for_odr (type
, outer_type
))
823 tree type_binfo
= NULL
;
825 /* Lookup BINFO with virtual table. For normal types it is always last
827 for (i
= type_binfos
.length () - 1; i
>= 0; i
--)
828 if (BINFO_OFFSET (type_binfos
[i
]) == BINFO_OFFSET (binfo
))
830 type_binfo
= type_binfos
[i
];
833 if (BINFO_VTABLE (binfo
))
835 /* If this is duplicated BINFO for base shared by virtual inheritance,
836 we may not have its associated vtable. This is not a problem, since
837 we will walk it on the other path. */
840 tree inner_binfo
= get_binfo_at_offset (type_binfo
,
844 gcc_assert (odr_violation_reported
);
847 /* For types in anonymous namespace first check if the respective vtable
848 is alive. If not, we know the type can't be called. */
849 if (!flag_ltrans
&& anonymous
)
851 tree vtable
= BINFO_VTABLE (inner_binfo
);
854 if (TREE_CODE (vtable
) == POINTER_PLUS_EXPR
)
855 vtable
= TREE_OPERAND (TREE_OPERAND (vtable
, 0), 0);
856 vnode
= varpool_get_node (vtable
);
857 if (!vnode
|| !vnode
->definition
)
860 gcc_assert (inner_binfo
);
861 if (bases_to_consider
862 ? !pointer_set_contains (matched_vtables
, BINFO_VTABLE (inner_binfo
))
863 : !pointer_set_insert (matched_vtables
, BINFO_VTABLE (inner_binfo
)))
866 tree target
= gimple_get_virt_method_for_binfo (otr_token
,
869 if (!bases_to_consider
)
870 maybe_record_node (nodes
, target
, inserted
, can_refer
, completep
);
871 /* Destructors are never called via construction vtables. */
872 else if (!target
|| !DECL_CXX_DESTRUCTOR_P (target
))
873 bases_to_consider
->safe_push (target
);
879 for (i
= 0; BINFO_BASE_ITERATE (binfo
, i
, base_binfo
); i
++)
880 /* Walking bases that have no virtual method is pointless excercise. */
881 if (polymorphic_type_binfo_p (base_binfo
))
882 record_target_from_binfo (nodes
, bases_to_consider
, base_binfo
, otr_type
,
884 otr_token
, outer_type
, offset
, inserted
,
885 matched_vtables
, anonymous
, completep
);
886 if (BINFO_VTABLE (binfo
))
890 /* Lookup virtual methods matching OTR_TYPE (with OFFSET and OTR_TOKEN)
891 of TYPE, insert them to NODES, recurse into derived nodes.
892 INSERTED is used to avoid duplicate insertions of methods into NODES.
893 MATCHED_VTABLES are used to avoid duplicate walking vtables.
894 Clear COMPLETEP if unreferable target is found.
896 If CONSIDER_CONSTURCTION is true, record to BASES_TO_CONSDIER
897 all cases where BASE_SKIPPED is true (because the base is abstract
901 possible_polymorphic_call_targets_1 (vec
<cgraph_node
*> &nodes
,
902 pointer_set_t
*inserted
,
903 pointer_set_t
*matched_vtables
,
906 HOST_WIDE_INT otr_token
,
908 HOST_WIDE_INT offset
,
910 vec
<tree
> &bases_to_consider
,
911 bool consider_construction
)
913 tree binfo
= TYPE_BINFO (type
->type
);
915 vec
<tree
> type_binfos
= vNULL
;
916 bool possibly_instantiated
= type_possibly_instantiated_p (type
->type
);
918 /* We may need to consider types w/o instances because of possible derived
919 types using their methods either directly or via construction vtables.
920 We are safe to skip them when all derivations are known, since we will
922 This is done by recording them to BASES_TO_CONSIDER array. */
923 if (possibly_instantiated
|| consider_construction
)
925 record_target_from_binfo (nodes
,
926 (!possibly_instantiated
927 && type_all_derivations_known_p (type
->type
))
928 ? &bases_to_consider
: NULL
,
929 binfo
, otr_type
, type_binfos
, otr_token
,
931 inserted
, matched_vtables
,
932 type
->anonymous_namespace
, completep
);
934 type_binfos
.release ();
935 for (i
= 0; i
< type
->derived_types
.length (); i
++)
936 possible_polymorphic_call_targets_1 (nodes
, inserted
,
939 type
->derived_types
[i
],
940 otr_token
, outer_type
, offset
, completep
,
941 bases_to_consider
, consider_construction
);
944 /* Cache of queries for polymorphic call targets.
946 Enumerating all call targets may get expensive when there are many
947 polymorphic calls in the program, so we memoize all the previous
948 queries and avoid duplicated work. */
950 struct polymorphic_call_target_d
952 HOST_WIDE_INT otr_token
;
953 ipa_polymorphic_call_context context
;
955 vec
<cgraph_node
*> targets
;
956 int nonconstruction_targets
;
960 /* Polymorphic call target cache helpers. */
962 struct polymorphic_call_target_hasher
964 typedef polymorphic_call_target_d value_type
;
965 typedef polymorphic_call_target_d compare_type
;
966 static inline hashval_t
hash (const value_type
*);
967 static inline bool equal (const value_type
*, const compare_type
*);
968 static inline void remove (value_type
*);
971 /* Return the computed hashcode for ODR_QUERY. */
974 polymorphic_call_target_hasher::hash (const value_type
*odr_query
)
978 hash
= iterative_hash_host_wide_int
979 (odr_query
->otr_token
,
980 odr_query
->type
->id
);
981 hash
= iterative_hash_hashval_t (TYPE_UID (odr_query
->context
.outer_type
),
983 hash
= iterative_hash_host_wide_int (odr_query
->context
.offset
, hash
);
984 return iterative_hash_hashval_t
985 (((int)odr_query
->context
.maybe_in_construction
<< 1)
986 | (int)odr_query
->context
.maybe_derived_type
, hash
);
989 /* Compare cache entries T1 and T2. */
992 polymorphic_call_target_hasher::equal (const value_type
*t1
,
993 const compare_type
*t2
)
995 return (t1
->type
== t2
->type
&& t1
->otr_token
== t2
->otr_token
996 && t1
->context
.offset
== t2
->context
.offset
997 && t1
->context
.outer_type
== t2
->context
.outer_type
998 && t1
->context
.maybe_in_construction
999 == t2
->context
.maybe_in_construction
1000 && t1
->context
.maybe_derived_type
== t2
->context
.maybe_derived_type
);
1003 /* Remove entry in polymorphic call target cache hash. */
1006 polymorphic_call_target_hasher::remove (value_type
*v
)
1008 v
->targets
.release ();
1012 /* Polymorphic call target query cache. */
1014 typedef hash_table
<polymorphic_call_target_hasher
>
1015 polymorphic_call_target_hash_type
;
1016 static polymorphic_call_target_hash_type
*polymorphic_call_target_hash
;
1018 /* Destroy polymorphic call target query cache. */
1021 free_polymorphic_call_targets_hash ()
1023 if (cached_polymorphic_call_targets
)
1025 delete polymorphic_call_target_hash
;
1026 polymorphic_call_target_hash
= NULL
;
1027 pointer_set_destroy (cached_polymorphic_call_targets
);
1028 cached_polymorphic_call_targets
= NULL
;
1032 /* When virtual function is removed, we may need to flush the cache. */
1035 devirt_node_removal_hook (struct cgraph_node
*n
, void *d ATTRIBUTE_UNUSED
)
1037 if (cached_polymorphic_call_targets
1038 && pointer_set_contains (cached_polymorphic_call_targets
, n
))
1039 free_polymorphic_call_targets_hash ();
1042 /* CONTEXT->OUTER_TYPE is a type of memory object where object of EXPECTED_TYPE
1043 is contained at CONTEXT->OFFSET. Walk the memory representation of
1044 CONTEXT->OUTER_TYPE and find the outermost class type that match
1045 EXPECTED_TYPE or contain EXPECTED_TYPE as a base. Update CONTEXT
1048 For example when CONTEXT represents type
1054 and we look for type at offset sizeof(int), we end up with B and offset 0.
1055 If the same is produced by multiple inheritance, we end up with A and offset
1058 If we can not find corresponding class, give up by setting
1059 CONTEXT->OUTER_TYPE to EXPECTED_TYPE and CONTEXT->OFFSET to NULL.
1060 Return true when lookup was sucesful. */
1063 get_class_context (ipa_polymorphic_call_context
*context
,
1066 tree type
= context
->outer_type
;
1067 HOST_WIDE_INT offset
= context
->offset
;
1069 /* Find the sub-object the constant actually refers to and mark whether it is
1070 an artificial one (as opposed to a user-defined one). */
1073 HOST_WIDE_INT pos
, size
;
1076 /* On a match, just return what we found. */
1077 if (TREE_CODE (type
) == TREE_CODE (expected_type
)
1078 && types_same_for_odr (type
, expected_type
))
1080 /* Type can not contain itself on an non-zero offset. In that case
1084 gcc_assert (offset
== 0);
1088 /* Walk fields and find corresponding on at OFFSET. */
1089 if (TREE_CODE (type
) == RECORD_TYPE
)
1091 for (fld
= TYPE_FIELDS (type
); fld
; fld
= DECL_CHAIN (fld
))
1093 if (TREE_CODE (fld
) != FIELD_DECL
)
1096 pos
= int_bit_position (fld
);
1097 size
= tree_to_uhwi (DECL_SIZE (fld
));
1098 if (pos
<= offset
&& (pos
+ size
) > offset
)
1105 type
= TREE_TYPE (fld
);
1107 /* DECL_ARTIFICIAL represents a basetype. */
1108 if (!DECL_ARTIFICIAL (fld
))
1110 context
->outer_type
= type
;
1111 context
->offset
= offset
;
1112 /* As soon as we se an field containing the type,
1113 we know we are not looking for derivations. */
1114 context
->maybe_derived_type
= false;
1117 else if (TREE_CODE (type
) == ARRAY_TYPE
)
1119 tree subtype
= TREE_TYPE (type
);
1121 /* Give up if we don't know array size. */
1122 if (!tree_fits_shwi_p (TYPE_SIZE (subtype
))
1123 || !tree_to_shwi (TYPE_SIZE (subtype
)) <= 0)
1125 offset
= offset
% tree_to_shwi (TYPE_SIZE (subtype
));
1127 context
->outer_type
= type
;
1128 context
->offset
= offset
;
1129 context
->maybe_derived_type
= false;
1131 /* Give up on anything else. */
1136 /* If we failed to find subtype we look for, give up and fall back to the
1137 most generic query. */
1139 context
->outer_type
= expected_type
;
1140 context
->offset
= 0;
1141 context
->maybe_derived_type
= true;
1142 context
->maybe_in_construction
= true;
1143 /* POD can be changed to an instance of a polymorphic type by
1144 placement new. Here we play safe and assume that any
1145 non-polymorphic type is POD. */
1146 if ((TREE_CODE (type
) != RECORD_TYPE
1147 || !TYPE_BINFO (type
)
1148 || !polymorphic_type_binfo_p (TYPE_BINFO (type
)))
1149 && (TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
1150 || (offset
+ tree_to_uhwi (TYPE_SIZE (expected_type
)) <=
1151 tree_to_uhwi (TYPE_SIZE (type
)))))
1156 /* Return true if OUTER_TYPE contains OTR_TYPE at OFFSET. */
1159 contains_type_p (tree outer_type
, HOST_WIDE_INT offset
,
1162 ipa_polymorphic_call_context context
= {offset
, outer_type
,
1164 return get_class_context (&context
, otr_type
);
1167 /* Lookup base of BINFO that has virtual table VTABLE with OFFSET. */
1170 subbinfo_with_vtable_at_offset (tree binfo
, unsigned HOST_WIDE_INT offset
,
1173 tree v
= BINFO_VTABLE (binfo
);
1176 unsigned HOST_WIDE_INT this_offset
;
1180 if (!vtable_pointer_value_to_vtable (v
, &v
, &this_offset
))
1183 if (offset
== this_offset
1184 && DECL_ASSEMBLER_NAME (v
) == DECL_ASSEMBLER_NAME (vtable
))
1188 for (i
= 0; BINFO_BASE_ITERATE (binfo
, i
, base_binfo
); i
++)
1189 if (polymorphic_type_binfo_p (base_binfo
))
1191 base_binfo
= subbinfo_with_vtable_at_offset (base_binfo
, offset
, vtable
);
1198 /* T is known constant value of virtual table pointer.
1199 Store virtual table to V and its offset to OFFSET.
1200 Return false if T does not look like virtual table reference. */
1203 vtable_pointer_value_to_vtable (tree t
, tree
*v
, unsigned HOST_WIDE_INT
*offset
)
1205 /* We expect &MEM[(void *)&virtual_table + 16B].
1206 We obtain object's BINFO from the context of the virtual table.
1207 This one contains pointer to virtual table represented via
1208 POINTER_PLUS_EXPR. Verify that this pointer match to what
1209 we propagated through.
1211 In the case of virtual inheritance, the virtual tables may
1212 be nested, i.e. the offset may be different from 16 and we may
1213 need to dive into the type representation. */
1214 if (TREE_CODE (t
) == ADDR_EXPR
1215 && TREE_CODE (TREE_OPERAND (t
, 0)) == MEM_REF
1216 && TREE_CODE (TREE_OPERAND (TREE_OPERAND (t
, 0), 0)) == ADDR_EXPR
1217 && TREE_CODE (TREE_OPERAND (TREE_OPERAND (t
, 0), 1)) == INTEGER_CST
1218 && (TREE_CODE (TREE_OPERAND (TREE_OPERAND (TREE_OPERAND (t
, 0), 0), 0))
1220 && DECL_VIRTUAL_P (TREE_OPERAND (TREE_OPERAND
1221 (TREE_OPERAND (t
, 0), 0), 0)))
1223 *v
= TREE_OPERAND (TREE_OPERAND (TREE_OPERAND (t
, 0), 0), 0);
1224 *offset
= tree_to_uhwi (TREE_OPERAND (TREE_OPERAND (t
, 0), 1));
1228 /* Alternative representation, used by C++ frontend is POINTER_PLUS_EXPR.
1229 We need to handle it when T comes from static variable initializer or
1231 if (TREE_CODE (t
) == POINTER_PLUS_EXPR
)
1233 *offset
= tree_to_uhwi (TREE_OPERAND (t
, 1));
1234 t
= TREE_OPERAND (t
, 0);
1239 if (TREE_CODE (t
) != ADDR_EXPR
)
1241 *v
= TREE_OPERAND (t
, 0);
1245 /* T is known constant value of virtual table pointer. Return BINFO of the
1249 vtable_pointer_value_to_binfo (tree t
)
1252 unsigned HOST_WIDE_INT offset
;
1254 if (!vtable_pointer_value_to_vtable (t
, &vtable
, &offset
))
1257 /* FIXME: for stores of construction vtables we return NULL,
1258 because we do not have BINFO for those. Eventually we should fix
1259 our representation to allow this case to be handled, too.
1260 In the case we see store of BINFO we however may assume
1261 that standard folding will be ale to cope with it. */
1262 return subbinfo_with_vtable_at_offset (TYPE_BINFO (DECL_CONTEXT (vtable
)),
1266 /* Proudce polymorphic call context for call method of instance
1267 that is located within BASE (that is assumed to be a decl) at OFFSET. */
1270 get_polymorphic_call_info_for_decl (ipa_polymorphic_call_context
*context
,
1271 tree base
, HOST_WIDE_INT offset
)
1273 gcc_assert (DECL_P (base
));
1275 context
->outer_type
= TREE_TYPE (base
);
1276 context
->offset
= offset
;
1277 /* Make very conservative assumption that all objects
1278 may be in construction.
1279 TODO: ipa-prop already contains code to tell better.
1281 context
->maybe_in_construction
= true;
1282 context
->maybe_derived_type
= false;
1285 /* CST is an invariant (address of decl), try to get meaningful
1286 polymorphic call context for polymorphic call of method
1287 if instance of OTR_TYPE that is located at OFFSET of this invariant.
1288 Return FALSE if nothing meaningful can be found. */
1291 get_polymorphic_call_info_from_invariant (ipa_polymorphic_call_context
*context
,
1294 HOST_WIDE_INT offset
)
1296 HOST_WIDE_INT offset2
, size
, max_size
;
1299 if (TREE_CODE (cst
) != ADDR_EXPR
)
1302 cst
= TREE_OPERAND (cst
, 0);
1303 base
= get_ref_base_and_extent (cst
, &offset2
, &size
, &max_size
);
1304 if (!DECL_P (base
) || max_size
== -1 || max_size
!= size
)
1307 /* Only type inconsistent programs can have otr_type that is
1308 not part of outer type. */
1309 if (!contains_type_p (TREE_TYPE (base
), offset
, otr_type
))
1312 get_polymorphic_call_info_for_decl (context
, base
, offset
);
1316 /* Given REF call in FNDECL, determine class of the polymorphic
1317 call (OTR_TYPE), its token (OTR_TOKEN) and CONTEXT.
1318 Return pointer to object described by the context */
1321 get_polymorphic_call_info (tree fndecl
,
1324 HOST_WIDE_INT
*otr_token
,
1325 ipa_polymorphic_call_context
*context
)
1328 *otr_type
= obj_type_ref_class (ref
);
1329 *otr_token
= tree_to_uhwi (OBJ_TYPE_REF_TOKEN (ref
));
1331 /* Set up basic info in case we find nothing interesting in the analysis. */
1332 context
->outer_type
= *otr_type
;
1333 context
->offset
= 0;
1334 base_pointer
= OBJ_TYPE_REF_OBJECT (ref
);
1335 context
->maybe_derived_type
= true;
1336 context
->maybe_in_construction
= true;
1338 /* Walk SSA for outer object. */
1341 if (TREE_CODE (base_pointer
) == SSA_NAME
1342 && !SSA_NAME_IS_DEFAULT_DEF (base_pointer
)
1343 && SSA_NAME_DEF_STMT (base_pointer
)
1344 && gimple_assign_single_p (SSA_NAME_DEF_STMT (base_pointer
)))
1346 base_pointer
= gimple_assign_rhs1 (SSA_NAME_DEF_STMT (base_pointer
));
1347 STRIP_NOPS (base_pointer
);
1349 else if (TREE_CODE (base_pointer
) == ADDR_EXPR
)
1351 HOST_WIDE_INT size
, max_size
;
1352 HOST_WIDE_INT offset2
;
1353 tree base
= get_ref_base_and_extent (TREE_OPERAND (base_pointer
, 0),
1354 &offset2
, &size
, &max_size
);
1356 /* If this is a varying address, punt. */
1357 if ((TREE_CODE (base
) == MEM_REF
|| DECL_P (base
))
1359 && max_size
== size
)
1361 /* We found dereference of a pointer. Type of the pointer
1362 and MEM_REF is meaningless, but we can look futher. */
1363 if (TREE_CODE (base
) == MEM_REF
)
1365 base_pointer
= TREE_OPERAND (base
, 0);
1367 += offset2
+ mem_ref_offset (base
).to_short_addr () * BITS_PER_UNIT
;
1368 context
->outer_type
= NULL
;
1370 /* We found base object. In this case the outer_type
1372 else if (DECL_P (base
))
1374 gcc_assert (!POINTER_TYPE_P (TREE_TYPE (base
)));
1376 /* Only type inconsistent programs can have otr_type that is
1377 not part of outer type. */
1378 if (!contains_type_p (TREE_TYPE (base
),
1379 context
->offset
+ offset2
, *otr_type
))
1381 /* Use OTR_TOKEN = INT_MAX as a marker of probably type inconsistent
1382 code sequences; we arrange the calls to be builtin_unreachable
1384 *otr_token
= INT_MAX
;
1385 return base_pointer
;
1387 get_polymorphic_call_info_for_decl (context
, base
,
1388 context
->offset
+ offset2
);
1397 else if (TREE_CODE (base_pointer
) == POINTER_PLUS_EXPR
1398 && tree_fits_uhwi_p (TREE_OPERAND (base_pointer
, 1)))
1400 context
->offset
+= tree_to_shwi (TREE_OPERAND (base_pointer
, 1))
1402 base_pointer
= TREE_OPERAND (base_pointer
, 0);
1409 /* Try to determine type of the outer object. */
1410 if (TREE_CODE (base_pointer
) == SSA_NAME
1411 && SSA_NAME_IS_DEFAULT_DEF (base_pointer
)
1412 && TREE_CODE (SSA_NAME_VAR (base_pointer
)) == PARM_DECL
)
1414 /* See if parameter is THIS pointer of a method. */
1415 if (TREE_CODE (TREE_TYPE (fndecl
)) == METHOD_TYPE
1416 && SSA_NAME_VAR (base_pointer
) == DECL_ARGUMENTS (fndecl
))
1418 context
->outer_type
= TREE_TYPE (TREE_TYPE (base_pointer
));
1419 gcc_assert (TREE_CODE (context
->outer_type
) == RECORD_TYPE
);
1421 /* Dynamic casting has possibly upcasted the type
1422 in the hiearchy. In this case outer type is less
1423 informative than inner type and we should forget
1425 if (!contains_type_p (context
->outer_type
, context
->offset
,
1428 context
->outer_type
= NULL
;
1429 return base_pointer
;
1432 /* If the function is constructor or destructor, then
1433 the type is possibly in construction, but we know
1434 it is not derived type. */
1435 if (DECL_CXX_CONSTRUCTOR_P (fndecl
)
1436 || DECL_CXX_DESTRUCTOR_P (fndecl
))
1438 context
->maybe_in_construction
= true;
1439 context
->maybe_derived_type
= false;
1443 context
->maybe_derived_type
= true;
1444 context
->maybe_in_construction
= false;
1446 return base_pointer
;
1448 /* Non-PODs passed by value are really passed by invisible
1449 reference. In this case we also know the type of the
1451 if (DECL_BY_REFERENCE (SSA_NAME_VAR (base_pointer
)))
1453 context
->outer_type
= TREE_TYPE (TREE_TYPE (base_pointer
));
1454 gcc_assert (!POINTER_TYPE_P (context
->outer_type
));
1455 /* Only type inconsistent programs can have otr_type that is
1456 not part of outer type. */
1457 if (!contains_type_p (context
->outer_type
, context
->offset
,
1460 /* Use OTR_TOKEN = INT_MAX as a marker of probably type inconsistent
1461 code sequences; we arrange the calls to be builtin_unreachable
1463 *otr_token
= INT_MAX
;
1464 return base_pointer
;
1466 context
->maybe_derived_type
= false;
1467 context
->maybe_in_construction
= false;
1468 return base_pointer
;
1471 /* TODO: There are multiple ways to derive a type. For instance
1472 if BASE_POINTER is passed to an constructor call prior our refernece.
1473 We do not make this type of flow sensitive analysis yet. */
1474 return base_pointer
;
1477 /* Walk bases of OUTER_TYPE that contain OTR_TYPE at OFFSET.
1478 Lookup their respecitve virtual methods for OTR_TOKEN and OTR_TYPE
1479 and insert them to NODES.
1481 MATCHED_VTABLES and INSERTED is used to avoid duplicated work. */
1484 record_targets_from_bases (tree otr_type
,
1485 HOST_WIDE_INT otr_token
,
1487 HOST_WIDE_INT offset
,
1488 vec
<cgraph_node
*> &nodes
,
1489 pointer_set_t
*inserted
,
1490 pointer_set_t
*matched_vtables
,
1495 HOST_WIDE_INT pos
, size
;
1499 if (types_same_for_odr (outer_type
, otr_type
))
1502 for (fld
= TYPE_FIELDS (outer_type
); fld
; fld
= DECL_CHAIN (fld
))
1504 if (TREE_CODE (fld
) != FIELD_DECL
)
1507 pos
= int_bit_position (fld
);
1508 size
= tree_to_shwi (DECL_SIZE (fld
));
1509 if (pos
<= offset
&& (pos
+ size
) > offset
1510 /* Do not get confused by zero sized bases. */
1511 && polymorphic_type_binfo_p (TYPE_BINFO (TREE_TYPE (fld
))))
1514 /* Within a class type we should always find correcponding fields. */
1515 gcc_assert (fld
&& TREE_CODE (TREE_TYPE (fld
)) == RECORD_TYPE
);
1517 /* Nonbasetypes should have been stripped by outer_class_type. */
1518 gcc_assert (DECL_ARTIFICIAL (fld
));
1520 outer_type
= TREE_TYPE (fld
);
1523 base_binfo
= get_binfo_at_offset (TYPE_BINFO (outer_type
),
1527 gcc_assert (odr_violation_reported
);
1530 gcc_assert (base_binfo
);
1531 if (!pointer_set_insert (matched_vtables
, BINFO_VTABLE (base_binfo
)))
1534 tree target
= gimple_get_virt_method_for_binfo (otr_token
,
1537 if (!target
|| ! DECL_CXX_DESTRUCTOR_P (target
))
1538 maybe_record_node (nodes
, target
, inserted
, can_refer
, completep
);
1539 pointer_set_insert (matched_vtables
, BINFO_VTABLE (base_binfo
));
1544 /* When virtual table is removed, we may need to flush the cache. */
1547 devirt_variable_node_removal_hook (varpool_node
*n
,
1548 void *d ATTRIBUTE_UNUSED
)
1550 if (cached_polymorphic_call_targets
1551 && DECL_VIRTUAL_P (n
->decl
)
1552 && type_in_anonymous_namespace_p (DECL_CONTEXT (n
->decl
)))
1553 free_polymorphic_call_targets_hash ();
1556 /* Return vector containing possible targets of polymorphic call of type
1557 OTR_TYPE caling method OTR_TOKEN within type of OTR_OUTER_TYPE and OFFSET.
1558 If INCLUDE_BASES is true, walk also base types of OUTER_TYPES containig
1559 OTR_TYPE and include their virtual method. This is useful for types
1560 possibly in construction or destruction where the virtual table may
1561 temporarily change to one of base types. INCLUDE_DERIVER_TYPES make
1562 us to walk the inheritance graph for all derivations.
1564 OTR_TOKEN == INT_MAX is used to mark calls that are provably
1565 undefined and should be redirected to unreachable.
1567 If COMPLETEP is non-NULL, store true if the list is complete.
1568 CACHE_TOKEN (if non-NULL) will get stored to an unique ID of entry
1569 in the target cache. If user needs to visit every target list
1570 just once, it can memoize them.
1572 NONCONSTRUCTION_TARGETS specify number of targets with asumption that
1573 the type is not in the construction. Those targets appear first in the
1576 Returned vector is placed into cache. It is NOT caller's responsibility
1577 to free it. The vector can be freed on cgraph_remove_node call if
1578 the particular node is a virtual function present in the cache. */
1581 possible_polymorphic_call_targets (tree otr_type
,
1582 HOST_WIDE_INT otr_token
,
1583 ipa_polymorphic_call_context context
,
1586 int *nonconstruction_targetsp
)
1588 static struct cgraph_node_hook_list
*node_removal_hook_holder
;
1589 pointer_set_t
*inserted
;
1590 pointer_set_t
*matched_vtables
;
1591 vec
<cgraph_node
*> nodes
= vNULL
;
1592 vec
<tree
> bases_to_consider
= vNULL
;
1593 odr_type type
, outer_type
;
1594 polymorphic_call_target_d key
;
1595 polymorphic_call_target_d
**slot
;
1600 bool skipped
= false;
1602 /* If ODR is not initialized, return empty incomplete list. */
1608 *cache_token
= NULL
;
1609 if (nonconstruction_targetsp
)
1610 *nonconstruction_targetsp
= 0;
1614 /* If we hit type inconsistency, just return empty list of targets. */
1615 if (otr_token
== INT_MAX
)
1620 *cache_token
= NULL
;
1621 if (nonconstruction_targetsp
)
1622 *nonconstruction_targetsp
= 0;
1626 type
= get_odr_type (otr_type
, true);
1628 /* Lookup the outer class type we want to walk. */
1629 if (context
.outer_type
1630 && !get_class_context (&context
, otr_type
))
1635 *cache_token
= NULL
;
1636 if (nonconstruction_targetsp
)
1637 *nonconstruction_targetsp
= 0;
1641 /* We canonicalize our query, so we do not need extra hashtable entries. */
1643 /* Without outer type, we have no use for offset. Just do the
1644 basic search from innter type */
1645 if (!context
.outer_type
)
1647 context
.outer_type
= otr_type
;
1650 /* We need to update our hiearchy if the type does not exist. */
1651 outer_type
= get_odr_type (context
.outer_type
, true);
1652 /* If the type is complete, there are no derivations. */
1653 if (TYPE_FINAL_P (outer_type
->type
))
1654 context
.maybe_derived_type
= false;
1656 /* Initialize query cache. */
1657 if (!cached_polymorphic_call_targets
)
1659 cached_polymorphic_call_targets
= pointer_set_create ();
1660 polymorphic_call_target_hash
1661 = new polymorphic_call_target_hash_type (23);
1662 if (!node_removal_hook_holder
)
1664 node_removal_hook_holder
=
1665 cgraph_add_node_removal_hook (&devirt_node_removal_hook
, NULL
);
1666 varpool_add_node_removal_hook (&devirt_variable_node_removal_hook
,
1671 /* Lookup cached answer. */
1673 key
.otr_token
= otr_token
;
1674 key
.context
= context
;
1675 slot
= polymorphic_call_target_hash
->find_slot (&key
, INSERT
);
1677 *cache_token
= (void *)*slot
;
1681 *completep
= (*slot
)->complete
;
1682 if (nonconstruction_targetsp
)
1683 *nonconstruction_targetsp
= (*slot
)->nonconstruction_targets
;
1684 return (*slot
)->targets
;
1689 /* Do actual search. */
1690 timevar_push (TV_IPA_VIRTUAL_CALL
);
1691 *slot
= XCNEW (polymorphic_call_target_d
);
1693 *cache_token
= (void *)*slot
;
1694 (*slot
)->type
= type
;
1695 (*slot
)->otr_token
= otr_token
;
1696 (*slot
)->context
= context
;
1698 inserted
= pointer_set_create ();
1699 matched_vtables
= pointer_set_create ();
1701 /* First see virtual method of type itself. */
1702 binfo
= get_binfo_at_offset (TYPE_BINFO (outer_type
->type
),
1703 context
.offset
, otr_type
);
1705 target
= gimple_get_virt_method_for_binfo (otr_token
, binfo
,
1709 gcc_assert (odr_violation_reported
);
1713 /* Destructors are never called through construction virtual tables,
1714 because the type is always known. */
1715 if (target
&& DECL_CXX_DESTRUCTOR_P (target
))
1716 context
.maybe_in_construction
= false;
1720 /* In the case we get complete method, we don't need
1721 to walk derivations. */
1722 if (DECL_FINAL_P (target
))
1723 context
.maybe_derived_type
= false;
1726 /* If OUTER_TYPE is abstract, we know we are not seeing its instance. */
1727 if (type_possibly_instantiated_p (outer_type
->type
))
1728 maybe_record_node (nodes
, target
, inserted
, can_refer
, &complete
);
1732 gcc_assert (in_lto_p
|| context
.maybe_derived_type
);
1735 pointer_set_insert (matched_vtables
, BINFO_VTABLE (binfo
));
1737 /* Next walk recursively all derived types. */
1738 if (context
.maybe_derived_type
)
1740 /* For anonymous namespace types we can attempt to build full type.
1741 All derivations must be in this unit (unless we see partial unit). */
1742 if (!type
->all_derivations_known
)
1744 for (i
= 0; i
< outer_type
->derived_types
.length(); i
++)
1745 possible_polymorphic_call_targets_1 (nodes
, inserted
,
1748 outer_type
->derived_types
[i
],
1749 otr_token
, outer_type
->type
,
1750 context
.offset
, &complete
,
1752 context
.maybe_in_construction
);
1755 /* Finally walk bases, if asked to. */
1756 (*slot
)->nonconstruction_targets
= nodes
.length();
1758 /* Destructors are never called through construction virtual tables,
1759 because the type is always known. One of entries may be cxa_pure_virtual
1760 so look to at least two of them. */
1761 if (context
.maybe_in_construction
)
1762 for (i
=0 ; i
< MIN (nodes
.length (), 2); i
++)
1763 if (DECL_CXX_DESTRUCTOR_P (nodes
[i
]->decl
))
1764 context
.maybe_in_construction
= false;
1765 if (context
.maybe_in_construction
)
1767 if (type
!= outer_type
1769 || (context
.maybe_derived_type
1770 && !type_all_derivations_known_p (outer_type
->type
))))
1771 record_targets_from_bases (otr_type
, otr_token
, outer_type
->type
,
1772 context
.offset
, nodes
, inserted
,
1773 matched_vtables
, &complete
);
1775 maybe_record_node (nodes
, target
, inserted
, can_refer
, &complete
);
1776 for (i
= 0; i
< bases_to_consider
.length(); i
++)
1777 maybe_record_node (nodes
, bases_to_consider
[i
], inserted
, can_refer
, &complete
);
1779 bases_to_consider
.release();
1781 (*slot
)->targets
= nodes
;
1782 (*slot
)->complete
= complete
;
1784 *completep
= complete
;
1785 if (nonconstruction_targetsp
)
1786 *nonconstruction_targetsp
= (*slot
)->nonconstruction_targets
;
1788 pointer_set_destroy (inserted
);
1789 pointer_set_destroy (matched_vtables
);
1790 timevar_pop (TV_IPA_VIRTUAL_CALL
);
1794 /* Dump all possible targets of a polymorphic call. */
1797 dump_possible_polymorphic_call_targets (FILE *f
,
1799 HOST_WIDE_INT otr_token
,
1800 const ipa_polymorphic_call_context
&ctx
)
1802 vec
<cgraph_node
*> targets
;
1804 odr_type type
= get_odr_type (otr_type
, false);
1806 int nonconstruction
;
1810 targets
= possible_polymorphic_call_targets (otr_type
, otr_token
,
1812 &final
, NULL
, &nonconstruction
);
1813 fprintf (f
, " Targets of polymorphic call of type %i:", type
->id
);
1814 print_generic_expr (f
, type
->type
, TDF_SLIM
);
1815 fprintf (f
, " token %i\n", (int)otr_token
);
1816 if (ctx
.outer_type
|| ctx
.offset
)
1818 fprintf (f
, " Contained in type:");
1819 print_generic_expr (f
, ctx
.outer_type
, TDF_SLIM
);
1820 fprintf (f
, " at offset "HOST_WIDE_INT_PRINT_DEC
"\n",
1824 fprintf (f
, " %s%s%s\n ",
1825 final
? "This is a complete list." :
1826 "This is partial list; extra targets may be defined in other units.",
1827 ctx
.maybe_in_construction
? " (base types included)" : "",
1828 ctx
.maybe_derived_type
? " (derived types included)" : "");
1829 for (i
= 0; i
< targets
.length (); i
++)
1832 if (i
== (unsigned)nonconstruction
)
1833 fprintf (f
, "\n If the type is in construction,"
1834 " then additional tarets are:\n"
1837 name
= cplus_demangle_v3 (targets
[i
]->asm_name (), 0);
1838 fprintf (f
, " %s/%i", name
? name
: targets
[i
]->name (), targets
[i
]->order
);
1841 if (!targets
[i
]->definition
)
1842 fprintf (f
, " (no definition%s)",
1843 DECL_DECLARED_INLINE_P (targets
[i
]->decl
)
1846 fprintf (f
, "\n\n");
1850 /* Return true if N can be possibly target of a polymorphic call of
1851 OTR_TYPE/OTR_TOKEN. */
1854 possible_polymorphic_call_target_p (tree otr_type
,
1855 HOST_WIDE_INT otr_token
,
1856 const ipa_polymorphic_call_context
&ctx
,
1857 struct cgraph_node
*n
)
1859 vec
<cgraph_node
*> targets
;
1861 enum built_in_function fcode
;
1864 if (TREE_CODE (TREE_TYPE (n
->decl
)) == FUNCTION_TYPE
1865 && ((fcode
= DECL_FUNCTION_CODE (n
->decl
))
1866 == BUILT_IN_UNREACHABLE
1867 || fcode
== BUILT_IN_TRAP
))
1872 targets
= possible_polymorphic_call_targets (otr_type
, otr_token
, ctx
, &final
);
1873 for (i
= 0; i
< targets
.length (); i
++)
1874 if (symtab_semantically_equivalent_p (n
, targets
[i
]))
1877 /* At a moment we allow middle end to dig out new external declarations
1878 as a targets of polymorphic calls. */
1879 if (!final
&& !n
->definition
)
1885 /* After callgraph construction new external nodes may appear.
1886 Add them into the graph. */
1889 update_type_inheritance_graph (void)
1891 struct cgraph_node
*n
;
1895 free_polymorphic_call_targets_hash ();
1896 timevar_push (TV_IPA_INHERITANCE
);
1897 /* We reconstruct the graph starting from types of all methods seen in the
1899 FOR_EACH_FUNCTION (n
)
1900 if (DECL_VIRTUAL_P (n
->decl
)
1902 && symtab_real_symbol_p (n
))
1903 get_odr_type (method_class_type (TREE_TYPE (n
->decl
)), true);
1904 timevar_pop (TV_IPA_INHERITANCE
);
1908 /* Return true if N looks like likely target of a polymorphic call.
1909 Rule out cxa_pure_virtual, noreturns, function declared cold and
1910 other obvious cases. */
1913 likely_target_p (struct cgraph_node
*n
)
1916 /* cxa_pure_virtual and similar things are not likely. */
1917 if (TREE_CODE (TREE_TYPE (n
->decl
)) != METHOD_TYPE
)
1919 flags
= flags_from_decl_or_type (n
->decl
);
1920 if (flags
& ECF_NORETURN
)
1922 if (lookup_attribute ("cold",
1923 DECL_ATTRIBUTES (n
->decl
)))
1925 if (n
->frequency
< NODE_FREQUENCY_NORMAL
)
1927 /* If there are no virtual tables refering the target alive,
1928 the only way the target can be called is an instance comming from other
1929 compilation unit; speculative devirtualization is build around an
1930 assumption that won't happen. */
1931 if (!referenced_from_vtable_p (n
))
1936 /* The ipa-devirt pass.
1937 When polymorphic call has only one likely target in the unit,
1938 turn it into speculative call. */
1943 struct cgraph_node
*n
;
1944 struct pointer_set_t
*bad_call_targets
= pointer_set_create ();
1945 struct cgraph_edge
*e
;
1947 int npolymorphic
= 0, nspeculated
= 0, nconverted
= 0, ncold
= 0;
1948 int nmultiple
= 0, noverwritable
= 0, ndevirtualized
= 0, nnotdefined
= 0;
1949 int nwrong
= 0, nok
= 0, nexternal
= 0, nartificial
= 0;
1951 FOR_EACH_DEFINED_FUNCTION (n
)
1953 bool update
= false;
1954 if (dump_file
&& n
->indirect_calls
)
1955 fprintf (dump_file
, "\n\nProcesing function %s/%i\n",
1956 n
->name (), n
->order
);
1957 for (e
= n
->indirect_calls
; e
; e
= e
->next_callee
)
1958 if (e
->indirect_info
->polymorphic
)
1960 struct cgraph_node
*likely_target
= NULL
;
1963 int nonconstruction_targets
;
1964 vec
<cgraph_node
*>targets
1965 = possible_polymorphic_call_targets
1966 (e
, &final
, &cache_token
, &nonconstruction_targets
);
1970 dump_possible_polymorphic_call_targets
1975 if (!cgraph_maybe_hot_edge_p (e
))
1978 fprintf (dump_file
, "Call is cold\n\n");
1985 fprintf (dump_file
, "Call is aready speculated\n\n");
1988 /* When dumping see if we agree with speculation. */
1992 if (pointer_set_contains (bad_call_targets
,
1996 fprintf (dump_file
, "Target list is known to be useless\n\n");
2000 for (i
= 0; i
< targets
.length (); i
++)
2001 if (likely_target_p (targets
[i
]))
2005 if (i
< (unsigned) nonconstruction_targets
)
2007 likely_target
= NULL
;
2009 fprintf (dump_file
, "More than one likely target\n\n");
2014 likely_target
= targets
[i
];
2018 pointer_set_insert (bad_call_targets
, cache_token
);
2021 /* This is reached only when dumping; check if we agree or disagree
2022 with the speculation. */
2025 struct cgraph_edge
*e2
;
2026 struct ipa_ref
*ref
;
2027 cgraph_speculative_call_info (e
, e2
, e
, ref
);
2028 if (cgraph_function_or_thunk_node (e2
->callee
, NULL
)
2029 == cgraph_function_or_thunk_node (likely_target
, NULL
))
2031 fprintf (dump_file
, "We agree with speculation\n\n");
2036 fprintf (dump_file
, "We disagree with speculation\n\n");
2041 if (!likely_target
->definition
)
2044 fprintf (dump_file
, "Target is not an definition\n\n");
2048 /* Do not introduce new references to external symbols. While we
2049 can handle these just well, it is common for programs to
2050 incorrectly with headers defining methods they are linked
2052 if (DECL_EXTERNAL (likely_target
->decl
))
2055 fprintf (dump_file
, "Target is external\n\n");
2059 /* Don't use an implicitly-declared destructor (c++/58678). */
2060 struct cgraph_node
*non_thunk_target
2061 = cgraph_function_node (likely_target
);
2062 if (DECL_ARTIFICIAL (non_thunk_target
->decl
)
2063 && DECL_COMDAT (non_thunk_target
->decl
))
2066 fprintf (dump_file
, "Target is artificial\n\n");
2070 if (cgraph_function_body_availability (likely_target
)
2071 <= AVAIL_OVERWRITABLE
2072 && symtab_can_be_discarded (likely_target
))
2075 fprintf (dump_file
, "Target is overwritable\n\n");
2079 else if (dbg_cnt (devirt
))
2081 if (dump_enabled_p ())
2083 location_t locus
= gimple_location (e
->call_stmt
);
2084 dump_printf_loc (MSG_OPTIMIZED_LOCATIONS
, locus
,
2085 "speculatively devirtualizing call in %s/%i to %s/%i\n",
2086 n
->name (), n
->order
,
2087 likely_target
->name (),
2088 likely_target
->order
);
2090 if (!symtab_can_be_discarded (likely_target
))
2093 alias
= cgraph (symtab_nonoverwritable_alias
2096 likely_target
= alias
;
2100 cgraph_turn_edge_to_speculative
2101 (e
, likely_target
, e
->count
* 8 / 10, e
->frequency
* 8 / 10);
2105 inline_update_overall_summary (n
);
2107 pointer_set_destroy (bad_call_targets
);
2111 "%i polymorphic calls, %i devirtualized,"
2112 " %i speculatively devirtualized, %i cold\n"
2113 "%i have multiple targets, %i overwritable,"
2114 " %i already speculated (%i agree, %i disagree),"
2115 " %i external, %i not defined, %i artificial\n",
2116 npolymorphic
, ndevirtualized
, nconverted
, ncold
,
2117 nmultiple
, noverwritable
, nspeculated
, nok
, nwrong
,
2118 nexternal
, nnotdefined
, nartificial
);
2119 return ndevirtualized
? TODO_remove_functions
: 0;
2124 const pass_data pass_data_ipa_devirt
=
2126 IPA_PASS
, /* type */
2127 "devirt", /* name */
2128 OPTGROUP_NONE
, /* optinfo_flags */
2129 true, /* has_execute */
2130 TV_IPA_DEVIRT
, /* tv_id */
2131 0, /* properties_required */
2132 0, /* properties_provided */
2133 0, /* properties_destroyed */
2134 0, /* todo_flags_start */
2135 ( TODO_dump_symtab
), /* todo_flags_finish */
2138 class pass_ipa_devirt
: public ipa_opt_pass_d
2141 pass_ipa_devirt (gcc::context
*ctxt
)
2142 : ipa_opt_pass_d (pass_data_ipa_devirt
, ctxt
,
2143 NULL
, /* generate_summary */
2144 NULL
, /* write_summary */
2145 NULL
, /* read_summary */
2146 NULL
, /* write_optimization_summary */
2147 NULL
, /* read_optimization_summary */
2148 NULL
, /* stmt_fixup */
2149 0, /* function_transform_todo_flags_start */
2150 NULL
, /* function_transform */
2151 NULL
) /* variable_transform */
2154 /* opt_pass methods: */
2155 virtual bool gate (function
*)
2157 return (flag_devirtualize
2158 && flag_devirtualize_speculatively
2162 virtual unsigned int execute (function
*) { return ipa_devirt (); }
2164 }; // class pass_ipa_devirt
2169 make_pass_ipa_devirt (gcc::context
*ctxt
)
2171 return new pass_ipa_devirt (ctxt
);
2174 #include "gt-ipa-devirt.h"