1 /* Perform -*- C++ -*- constant expression evaluation, including calls to
2 constexpr functions. These routines are used both during actual parsing
3 and during the instantiation of template functions.
5 Copyright (C) 1998-2018 Free Software Foundation, Inc.
7 This file is part of GCC.
9 GCC is free software; you can redistribute it and/or modify it
10 under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3, or (at your option)
14 GCC is distributed in the hope that it will be useful, but
15 WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with GCC; see the file COPYING3. If not see
21 <http://www.gnu.org/licenses/>. */
25 #include "coretypes.h"
28 #include "c-family/c-objc.h"
29 #include "tree-iterator.h"
32 #include "tree-inline.h"
34 #include "gimple-fold.h"
37 static bool verify_constant (tree
, bool, bool *, bool *);
38 #define VERIFY_CONSTANT(X) \
40 if (verify_constant ((X), ctx->quiet, non_constant_p, overflow_p)) \
44 /* Returns true iff FUN is an instantiation of a constexpr function
45 template or a defaulted constexpr function. */
48 is_instantiation_of_constexpr (tree fun
)
50 return ((DECL_TEMPLOID_INSTANTIATION (fun
)
51 && DECL_DECLARED_CONSTEXPR_P (DECL_TI_TEMPLATE (fun
)))
52 || (DECL_DEFAULTED_FN (fun
)
53 && DECL_DECLARED_CONSTEXPR_P (fun
)));
56 /* Return true if T is a literal type. */
59 literal_type_p (tree t
)
63 || TREE_CODE (t
) == REFERENCE_TYPE
64 || (VOID_TYPE_P (t
) && cxx_dialect
>= cxx14
))
68 t
= complete_type (t
);
69 gcc_assert (COMPLETE_TYPE_P (t
) || errorcount
);
70 return CLASSTYPE_LITERAL_P (t
);
72 if (TREE_CODE (t
) == ARRAY_TYPE
)
73 return literal_type_p (strip_array_types (t
));
77 /* If DECL is a variable declared `constexpr', require its type
78 be literal. Return error_mark_node if we give an error, the
82 ensure_literal_type_for_constexpr_object (tree decl
)
84 tree type
= TREE_TYPE (decl
);
86 && (DECL_DECLARED_CONSTEXPR_P (decl
)
87 || var_in_constexpr_fn (decl
))
88 && !processing_template_decl
)
90 tree stype
= strip_array_types (type
);
91 if (CLASS_TYPE_P (stype
) && !COMPLETE_TYPE_P (complete_type (stype
)))
92 /* Don't complain here, we'll complain about incompleteness
93 when we try to initialize the variable. */;
94 else if (!literal_type_p (type
))
96 if (DECL_DECLARED_CONSTEXPR_P (decl
))
98 error ("the type %qT of %<constexpr%> variable %qD "
99 "is not literal", type
, decl
);
100 explain_non_literal_class (type
);
101 decl
= error_mark_node
;
105 if (!is_instantiation_of_constexpr (current_function_decl
))
107 error ("variable %qD of non-literal type %qT in %<constexpr%> "
108 "function", decl
, type
);
109 explain_non_literal_class (type
);
110 decl
= error_mark_node
;
112 cp_function_chain
->invalid_constexpr
= true;
115 else if (DECL_DECLARED_CONSTEXPR_P (decl
)
116 && variably_modified_type_p (type
, NULL_TREE
))
118 error ("%<constexpr%> variable %qD has variably-modified type %qT",
120 decl
= error_mark_node
;
126 /* Representation of entries in the constexpr function definition table. */
128 struct GTY((for_user
)) constexpr_fundef
{
133 struct constexpr_fundef_hasher
: ggc_ptr_hash
<constexpr_fundef
>
135 static hashval_t
hash (constexpr_fundef
*);
136 static bool equal (constexpr_fundef
*, constexpr_fundef
*);
139 /* This table holds all constexpr function definitions seen in
140 the current translation unit. */
142 static GTY (()) hash_table
<constexpr_fundef_hasher
> *constexpr_fundef_table
;
144 /* Utility function used for managing the constexpr function table.
145 Return true if the entries pointed to by P and Q are for the
146 same constexpr function. */
149 constexpr_fundef_hasher::equal (constexpr_fundef
*lhs
, constexpr_fundef
*rhs
)
151 return lhs
->decl
== rhs
->decl
;
154 /* Utility function used for managing the constexpr function table.
155 Return a hash value for the entry pointed to by Q. */
158 constexpr_fundef_hasher::hash (constexpr_fundef
*fundef
)
160 return DECL_UID (fundef
->decl
);
163 /* Return a previously saved definition of function FUN. */
165 static constexpr_fundef
*
166 retrieve_constexpr_fundef (tree fun
)
168 constexpr_fundef fundef
= { NULL
, NULL
};
169 if (constexpr_fundef_table
== NULL
)
173 return constexpr_fundef_table
->find (&fundef
);
176 /* Check whether the parameter and return types of FUN are valid for a
177 constexpr function, and complain if COMPLAIN. */
180 is_valid_constexpr_fn (tree fun
, bool complain
)
184 if (DECL_INHERITED_CTOR (fun
)
185 && TREE_CODE (fun
) == TEMPLATE_DECL
)
189 error ("inherited constructor %qD is not %<constexpr%>",
190 DECL_INHERITED_CTOR (fun
));
194 for (tree parm
= FUNCTION_FIRST_USER_PARM (fun
);
195 parm
!= NULL_TREE
; parm
= TREE_CHAIN (parm
))
196 if (!literal_type_p (TREE_TYPE (parm
)))
201 error ("invalid type for parameter %d of %<constexpr%> "
202 "function %q+#D", DECL_PARM_INDEX (parm
), fun
);
203 explain_non_literal_class (TREE_TYPE (parm
));
208 if (LAMBDA_TYPE_P (CP_DECL_CONTEXT (fun
)) && cxx_dialect
< cxx17
)
212 inform (DECL_SOURCE_LOCATION (fun
),
213 "lambdas are implicitly %<constexpr%> only in C++17 and later");
215 else if (!DECL_CONSTRUCTOR_P (fun
))
217 tree rettype
= TREE_TYPE (TREE_TYPE (fun
));
218 if (!literal_type_p (rettype
))
223 error ("invalid return type %qT of %<constexpr%> function %q+D",
225 explain_non_literal_class (rettype
);
229 /* C++14 DR 1684 removed this restriction. */
230 if (cxx_dialect
< cxx14
231 && DECL_NONSTATIC_MEMBER_FUNCTION_P (fun
)
232 && !CLASSTYPE_LITERAL_P (DECL_CONTEXT (fun
)))
236 && pedwarn (DECL_SOURCE_LOCATION (fun
), OPT_Wpedantic
,
237 "enclosing class of %<constexpr%> non-static member "
238 "function %q+#D is not a literal type", fun
))
239 explain_non_literal_class (DECL_CONTEXT (fun
));
242 else if (CLASSTYPE_VBASECLASSES (DECL_CONTEXT (fun
)))
246 error ("%q#T has virtual base classes", DECL_CONTEXT (fun
));
252 /* Subroutine of build_data_member_initialization. MEMBER is a COMPONENT_REF
253 for a member of an anonymous aggregate, INIT is the initializer for that
254 member, and VEC_OUTER is the vector of constructor elements for the class
255 whose constructor we are processing. Add the initializer to the vector
256 and return true to indicate success. */
259 build_anon_member_initialization (tree member
, tree init
,
260 vec
<constructor_elt
, va_gc
> **vec_outer
)
262 /* MEMBER presents the relevant fields from the inside out, but we need
263 to build up the initializer from the outside in so that we can reuse
264 previously built CONSTRUCTORs if this is, say, the second field in an
265 anonymous struct. So we use a vec as a stack. */
266 auto_vec
<tree
, 2> fields
;
269 fields
.safe_push (TREE_OPERAND (member
, 1));
270 member
= TREE_OPERAND (member
, 0);
272 while (ANON_AGGR_TYPE_P (TREE_TYPE (member
))
273 && TREE_CODE (member
) == COMPONENT_REF
);
275 /* VEC has the constructor elements vector for the context of FIELD.
276 If FIELD is an anonymous aggregate, we will push inside it. */
277 vec
<constructor_elt
, va_gc
> **vec
= vec_outer
;
279 while (field
= fields
.pop(),
280 ANON_AGGR_TYPE_P (TREE_TYPE (field
)))
283 /* If there is already an outer constructor entry for the anonymous
284 aggregate FIELD, use it; otherwise, insert one. */
285 if (vec_safe_is_empty (*vec
)
286 || (*vec
)->last().index
!= field
)
288 ctor
= build_constructor (TREE_TYPE (field
), NULL
);
289 CONSTRUCTOR_APPEND_ELT (*vec
, field
, ctor
);
292 ctor
= (*vec
)->last().value
;
293 vec
= &CONSTRUCTOR_ELTS (ctor
);
296 /* Now we're at the innermost field, the one that isn't an anonymous
297 aggregate. Add its initializer to the CONSTRUCTOR and we're done. */
298 gcc_assert (fields
.is_empty());
299 CONSTRUCTOR_APPEND_ELT (*vec
, field
, init
);
304 /* Subroutine of build_constexpr_constructor_member_initializers.
305 The expression tree T represents a data member initialization
306 in a (constexpr) constructor definition. Build a pairing of
307 the data member with its initializer, and prepend that pair
308 to the existing initialization pair INITS. */
311 build_data_member_initialization (tree t
, vec
<constructor_elt
, va_gc
> **vec
)
314 if (TREE_CODE (t
) == CLEANUP_POINT_EXPR
)
315 t
= TREE_OPERAND (t
, 0);
316 if (TREE_CODE (t
) == EXPR_STMT
)
317 t
= TREE_OPERAND (t
, 0);
318 if (t
== error_mark_node
)
320 if (TREE_CODE (t
) == STATEMENT_LIST
)
322 tree_stmt_iterator i
;
323 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
325 if (! build_data_member_initialization (tsi_stmt (i
), vec
))
330 if (TREE_CODE (t
) == CLEANUP_STMT
)
332 /* We can't see a CLEANUP_STMT in a constructor for a literal class,
333 but we can in a constexpr constructor for a non-literal class. Just
334 ignore it; either all the initialization will be constant, in which
335 case the cleanup can't run, or it can't be constexpr.
336 Still recurse into CLEANUP_BODY. */
337 return build_data_member_initialization (CLEANUP_BODY (t
), vec
);
339 if (TREE_CODE (t
) == CONVERT_EXPR
)
340 t
= TREE_OPERAND (t
, 0);
341 if (TREE_CODE (t
) == INIT_EXPR
342 /* vptr initialization shows up as a MODIFY_EXPR. In C++14 we only
343 use what this function builds for cx_check_missing_mem_inits, and
344 assignment in the ctor body doesn't count. */
345 || (cxx_dialect
< cxx14
&& TREE_CODE (t
) == MODIFY_EXPR
))
347 member
= TREE_OPERAND (t
, 0);
348 init
= break_out_target_exprs (TREE_OPERAND (t
, 1));
350 else if (TREE_CODE (t
) == CALL_EXPR
)
352 tree fn
= get_callee_fndecl (t
);
353 if (!fn
|| !DECL_CONSTRUCTOR_P (fn
))
354 /* We're only interested in calls to subobject constructors. */
356 member
= CALL_EXPR_ARG (t
, 0);
357 /* We don't use build_cplus_new here because it complains about
358 abstract bases. Leaving the call unwrapped means that it has the
359 wrong type, but cxx_eval_constant_expression doesn't care. */
360 init
= break_out_target_exprs (t
);
362 else if (TREE_CODE (t
) == BIND_EXPR
)
363 return build_data_member_initialization (BIND_EXPR_BODY (t
), vec
);
365 /* Don't add anything else to the CONSTRUCTOR. */
367 if (INDIRECT_REF_P (member
))
368 member
= TREE_OPERAND (member
, 0);
369 if (TREE_CODE (member
) == NOP_EXPR
)
373 if (TREE_CODE (op
) == ADDR_EXPR
)
375 gcc_assert (same_type_ignoring_top_level_qualifiers_p
376 (TREE_TYPE (TREE_TYPE (op
)),
377 TREE_TYPE (TREE_TYPE (member
))));
378 /* Initializing a cv-qualified member; we need to look through
382 else if (op
== current_class_ptr
383 && (same_type_ignoring_top_level_qualifiers_p
384 (TREE_TYPE (TREE_TYPE (member
)),
385 current_class_type
)))
386 /* Delegating constructor. */
390 /* This is an initializer for an empty base; keep it for now so
391 we can check it in cxx_eval_bare_aggregate. */
392 gcc_assert (is_empty_class (TREE_TYPE (TREE_TYPE (member
))));
395 if (TREE_CODE (member
) == ADDR_EXPR
)
396 member
= TREE_OPERAND (member
, 0);
397 if (TREE_CODE (member
) == COMPONENT_REF
)
399 tree aggr
= TREE_OPERAND (member
, 0);
400 if (TREE_CODE (aggr
) == VAR_DECL
)
401 /* Initializing a local variable, don't add anything. */
403 if (TREE_CODE (aggr
) != COMPONENT_REF
)
404 /* Normal member initialization. */
405 member
= TREE_OPERAND (member
, 1);
406 else if (ANON_AGGR_TYPE_P (TREE_TYPE (aggr
)))
407 /* Initializing a member of an anonymous union. */
408 return build_anon_member_initialization (member
, init
, vec
);
410 /* We're initializing a vtable pointer in a base. Leave it as
411 COMPONENT_REF so we remember the path to get to the vfield. */
412 gcc_assert (TREE_TYPE (member
) == vtbl_ptr_type_node
);
415 /* Value-initialization can produce multiple initializers for the
416 same field; use the last one. */
417 if (!vec_safe_is_empty (*vec
) && (*vec
)->last().index
== member
)
418 (*vec
)->last().value
= init
;
420 CONSTRUCTOR_APPEND_ELT (*vec
, member
, init
);
424 /* Subroutine of check_constexpr_ctor_body_1 and constexpr_fn_retval.
425 In C++11 mode checks that the TYPE_DECLs in the BIND_EXPR_VARS of a
426 BIND_EXPR conform to 7.1.5/3/4 on typedef and alias declarations. */
429 check_constexpr_bind_expr_vars (tree t
)
431 gcc_assert (TREE_CODE (t
) == BIND_EXPR
);
433 for (tree var
= BIND_EXPR_VARS (t
); var
; var
= DECL_CHAIN (var
))
434 if (TREE_CODE (var
) == TYPE_DECL
435 && DECL_IMPLICIT_TYPEDEF_P (var
)
436 && !LAMBDA_TYPE_P (TREE_TYPE (var
)))
441 /* Subroutine of check_constexpr_ctor_body. */
444 check_constexpr_ctor_body_1 (tree last
, tree list
)
446 switch (TREE_CODE (list
))
449 if (TREE_CODE (DECL_EXPR_DECL (list
)) == USING_DECL
450 || TREE_CODE (DECL_EXPR_DECL (list
)) == TYPE_DECL
)
454 case CLEANUP_POINT_EXPR
:
455 return check_constexpr_ctor_body (last
, TREE_OPERAND (list
, 0),
459 if (!check_constexpr_bind_expr_vars (list
)
460 || !check_constexpr_ctor_body (last
, BIND_EXPR_BODY (list
),
467 case DEBUG_BEGIN_STMT
:
475 /* Make sure that there are no statements after LAST in the constructor
476 body represented by LIST. */
479 check_constexpr_ctor_body (tree last
, tree list
, bool complain
)
481 /* C++14 doesn't require a constexpr ctor to have an empty body. */
482 if (cxx_dialect
>= cxx14
)
486 if (TREE_CODE (list
) == STATEMENT_LIST
)
488 tree_stmt_iterator i
= tsi_last (list
);
489 for (; !tsi_end_p (i
); tsi_prev (&i
))
491 tree t
= tsi_stmt (i
);
494 if (!check_constexpr_ctor_body_1 (last
, t
))
501 else if (list
!= last
502 && !check_constexpr_ctor_body_1 (last
, list
))
507 error ("%<constexpr%> constructor does not have empty body");
508 DECL_DECLARED_CONSTEXPR_P (current_function_decl
) = false;
513 /* V is a vector of constructor elements built up for the base and member
514 initializers of a constructor for TYPE. They need to be in increasing
515 offset order, which they might not be yet if TYPE has a primary base
516 which is not first in the base-clause or a vptr and at least one base
517 all of which are non-primary. */
519 static vec
<constructor_elt
, va_gc
> *
520 sort_constexpr_mem_initializers (tree type
, vec
<constructor_elt
, va_gc
> *v
)
522 tree pri
= CLASSTYPE_PRIMARY_BINFO (type
);
528 field_type
= BINFO_TYPE (pri
);
529 else if (TYPE_CONTAINS_VPTR_P (type
))
530 field_type
= vtbl_ptr_type_node
;
534 /* Find the element for the primary base or vptr and move it to the
535 beginning of the vec. */
536 for (i
= 0; vec_safe_iterate (v
, i
, &ce
); ++i
)
537 if (TREE_TYPE (ce
->index
) == field_type
)
540 if (i
> 0 && i
< vec_safe_length (v
))
542 vec
<constructor_elt
, va_gc
> &vref
= *v
;
543 constructor_elt elt
= vref
[i
];
552 /* Build compile-time evalable representations of member-initializer list
553 for a constexpr constructor. */
556 build_constexpr_constructor_member_initializers (tree type
, tree body
)
558 vec
<constructor_elt
, va_gc
> *vec
= NULL
;
561 switch (TREE_CODE (body
))
563 case MUST_NOT_THROW_EXPR
:
565 body
= TREE_OPERAND (body
, 0);
569 for (tree_stmt_iterator i
= tsi_start (body
);
570 !tsi_end_p (i
); tsi_next (&i
))
573 if (TREE_CODE (body
) == BIND_EXPR
)
579 body
= BIND_EXPR_BODY (body
);
586 if (TREE_CODE (body
) == CLEANUP_POINT_EXPR
)
588 body
= TREE_OPERAND (body
, 0);
589 if (TREE_CODE (body
) == EXPR_STMT
)
590 body
= TREE_OPERAND (body
, 0);
591 if (TREE_CODE (body
) == INIT_EXPR
592 && (same_type_ignoring_top_level_qualifiers_p
593 (TREE_TYPE (TREE_OPERAND (body
, 0)),
594 current_class_type
)))
597 return TREE_OPERAND (body
, 1);
599 ok
= build_data_member_initialization (body
, &vec
);
601 else if (TREE_CODE (body
) == STATEMENT_LIST
)
603 tree_stmt_iterator i
;
604 for (i
= tsi_start (body
); !tsi_end_p (i
); tsi_next (&i
))
606 ok
= build_data_member_initialization (tsi_stmt (i
), &vec
);
611 else if (TREE_CODE (body
) == TRY_BLOCK
)
613 error ("body of %<constexpr%> constructor cannot be "
614 "a function-try-block");
615 return error_mark_node
;
617 else if (EXPR_P (body
))
618 ok
= build_data_member_initialization (body
, &vec
);
620 gcc_assert (errorcount
> 0);
623 if (vec_safe_length (vec
) > 0)
625 /* In a delegating constructor, return the target. */
626 constructor_elt
*ce
= &(*vec
)[0];
627 if (ce
->index
== current_class_ptr
)
634 vec
= sort_constexpr_mem_initializers (type
, vec
);
635 return build_constructor (type
, vec
);
638 return error_mark_node
;
641 /* We have an expression tree T that represents a call, either CALL_EXPR
642 or AGGR_INIT_EXPR. If the call is lexically to a named function,
643 retrun the _DECL for that function. */
646 get_function_named_in_call (tree t
)
648 tree fun
= cp_get_callee (t
);
649 if (fun
&& TREE_CODE (fun
) == ADDR_EXPR
650 && TREE_CODE (TREE_OPERAND (fun
, 0)) == FUNCTION_DECL
)
651 fun
= TREE_OPERAND (fun
, 0);
655 /* Subroutine of register_constexpr_fundef. BODY is the body of a function
656 declared to be constexpr, or a sub-statement thereof. Returns the
657 return value if suitable, error_mark_node for a statement not allowed in
658 a constexpr function, or NULL_TREE if no return value was found. */
661 constexpr_fn_retval (tree body
)
663 switch (TREE_CODE (body
))
667 tree_stmt_iterator i
;
668 tree expr
= NULL_TREE
;
669 for (i
= tsi_start (body
); !tsi_end_p (i
); tsi_next (&i
))
671 tree s
= constexpr_fn_retval (tsi_stmt (i
));
672 if (s
== error_mark_node
)
673 return error_mark_node
;
674 else if (s
== NULL_TREE
)
675 /* Keep iterating. */;
677 /* Multiple return statements. */
678 return error_mark_node
;
686 return break_out_target_exprs (TREE_OPERAND (body
, 0));
690 tree decl
= DECL_EXPR_DECL (body
);
691 if (TREE_CODE (decl
) == USING_DECL
692 /* Accept __func__, __FUNCTION__, and __PRETTY_FUNCTION__. */
693 || DECL_ARTIFICIAL (decl
))
695 return error_mark_node
;
698 case CLEANUP_POINT_EXPR
:
699 return constexpr_fn_retval (TREE_OPERAND (body
, 0));
702 if (!check_constexpr_bind_expr_vars (body
))
703 return error_mark_node
;
704 return constexpr_fn_retval (BIND_EXPR_BODY (body
));
707 case DEBUG_BEGIN_STMT
:
712 tree fun
= get_function_named_in_call (body
);
714 && DECL_FUNCTION_CODE (fun
) == BUILT_IN_UNREACHABLE
)
720 return error_mark_node
;
724 /* Subroutine of register_constexpr_fundef. BODY is the DECL_SAVED_TREE of
725 FUN; do the necessary transformations to turn it into a single expression
726 that we can store in the hash table. */
729 massage_constexpr_body (tree fun
, tree body
)
731 if (DECL_CONSTRUCTOR_P (fun
))
732 body
= build_constexpr_constructor_member_initializers
733 (DECL_CONTEXT (fun
), body
);
734 else if (cxx_dialect
< cxx14
)
736 if (TREE_CODE (body
) == EH_SPEC_BLOCK
)
737 body
= EH_SPEC_STMTS (body
);
738 if (TREE_CODE (body
) == MUST_NOT_THROW_EXPR
)
739 body
= TREE_OPERAND (body
, 0);
740 body
= constexpr_fn_retval (body
);
745 /* CTYPE is a type constructed from BODY. Return true if some
746 bases/fields are uninitialized, and complain if COMPLAIN. */
749 cx_check_missing_mem_inits (tree ctype
, tree body
, bool complain
)
755 if (TREE_CODE (body
) != CONSTRUCTOR
)
757 nelts
= CONSTRUCTOR_NELTS (body
);
759 tree field
= TYPE_FIELDS (ctype
);
761 if (TREE_CODE (ctype
) == UNION_TYPE
)
763 if (nelts
== 0 && next_initializable_field (field
))
766 error ("%<constexpr%> constructor for union %qT must "
767 "initialize exactly one non-static data member", ctype
);
773 /* Iterate over the CONSTRUCTOR, checking any missing fields don't
774 need an explicit initialization. */
776 for (unsigned i
= 0; i
<= nelts
; ++i
)
778 tree index
= NULL_TREE
;
781 index
= CONSTRUCTOR_ELT (body
, i
)->index
;
782 /* Skip base and vtable inits. */
783 if (TREE_CODE (index
) != FIELD_DECL
784 || DECL_ARTIFICIAL (index
))
788 for (; field
!= index
; field
= DECL_CHAIN (field
))
791 if (TREE_CODE (field
) != FIELD_DECL
)
793 if (DECL_UNNAMED_BIT_FIELD (field
))
795 if (DECL_ARTIFICIAL (field
))
797 if (ANON_AGGR_TYPE_P (TREE_TYPE (field
)))
799 /* Recurse to check the anonummous aggregate member. */
800 bad
|= cx_check_missing_mem_inits
801 (TREE_TYPE (field
), NULL_TREE
, complain
);
802 if (bad
&& !complain
)
806 ftype
= strip_array_types (TREE_TYPE (field
));
807 if (type_has_constexpr_default_constructor (ftype
))
809 /* It's OK to skip a member with a trivial constexpr ctor.
810 A constexpr ctor that isn't trivial should have been
812 gcc_checking_assert (!TYPE_HAS_COMPLEX_DFLT (ftype
)
818 error ("member %qD must be initialized by mem-initializer "
819 "in %<constexpr%> constructor", field
);
820 inform (DECL_SOURCE_LOCATION (field
), "declared here");
823 if (field
== NULL_TREE
)
826 if (ANON_AGGR_TYPE_P (TREE_TYPE (index
)))
828 /* Check the anonymous aggregate initializer is valid. */
829 bad
|= cx_check_missing_mem_inits
830 (TREE_TYPE (index
), CONSTRUCTOR_ELT (body
, i
)->value
, complain
);
831 if (bad
&& !complain
)
834 field
= DECL_CHAIN (field
);
840 /* We are processing the definition of the constexpr function FUN.
841 Check that its BODY fulfills the propriate requirements and
842 enter it in the constexpr function definition table.
843 For constructor BODY is actually the TREE_LIST of the
844 member-initializer list. */
847 register_constexpr_fundef (tree fun
, tree body
)
849 constexpr_fundef entry
;
850 constexpr_fundef
**slot
;
852 if (!is_valid_constexpr_fn (fun
, !DECL_GENERATED_P (fun
)))
855 tree massaged
= massage_constexpr_body (fun
, body
);
856 if (massaged
== NULL_TREE
|| massaged
== error_mark_node
)
858 if (!DECL_CONSTRUCTOR_P (fun
))
859 error ("body of %<constexpr%> function %qD not a return-statement",
864 if (!potential_rvalue_constant_expression (massaged
))
866 if (!DECL_GENERATED_P (fun
))
867 require_potential_rvalue_constant_expression (massaged
);
871 if (DECL_CONSTRUCTOR_P (fun
)
872 && cx_check_missing_mem_inits (DECL_CONTEXT (fun
),
873 massaged
, !DECL_GENERATED_P (fun
)))
876 /* Create the constexpr function table if necessary. */
877 if (constexpr_fundef_table
== NULL
)
878 constexpr_fundef_table
879 = hash_table
<constexpr_fundef_hasher
>::create_ggc (101);
883 slot
= constexpr_fundef_table
->find_slot (&entry
, INSERT
);
885 gcc_assert (*slot
== NULL
);
886 *slot
= ggc_alloc
<constexpr_fundef
> ();
892 /* FUN is a non-constexpr function called in a context that requires a
893 constant expression. If it comes from a constexpr template, explain why
894 the instantiation isn't constexpr. */
897 explain_invalid_constexpr_fn (tree fun
)
899 static hash_set
<tree
> *diagnosed
;
902 /* Only diagnose defaulted functions, lambdas, or instantiations. */
903 if (!DECL_DEFAULTED_FN (fun
)
904 && !LAMBDA_TYPE_P (CP_DECL_CONTEXT (fun
))
905 && !is_instantiation_of_constexpr (fun
))
907 if (diagnosed
== NULL
)
908 diagnosed
= new hash_set
<tree
>;
909 if (diagnosed
->add (fun
))
910 /* Already explained. */
913 save_loc
= input_location
;
914 if (!lambda_static_thunk_p (fun
))
916 /* Diagnostics should completely ignore the static thunk, so leave
917 input_location set to our caller's location. */
918 input_location
= DECL_SOURCE_LOCATION (fun
);
919 inform (input_location
,
920 "%qD is not usable as a %<constexpr%> function because:", fun
);
922 /* First check the declaration. */
923 if (is_valid_constexpr_fn (fun
, true))
925 /* Then if it's OK, the body. */
926 if (!DECL_DECLARED_CONSTEXPR_P (fun
)
927 && !LAMBDA_TYPE_P (CP_DECL_CONTEXT (fun
)))
928 explain_implicit_non_constexpr (fun
);
931 body
= massage_constexpr_body (fun
, DECL_SAVED_TREE (fun
));
932 require_potential_rvalue_constant_expression (body
);
933 if (DECL_CONSTRUCTOR_P (fun
))
934 cx_check_missing_mem_inits (DECL_CONTEXT (fun
), body
, true);
937 input_location
= save_loc
;
940 /* Objects of this type represent calls to constexpr functions
941 along with the bindings of parameters to their arguments, for
942 the purpose of compile time evaluation. */
944 struct GTY((for_user
)) constexpr_call
{
945 /* Description of the constexpr function definition. */
946 constexpr_fundef
*fundef
;
947 /* Parameter bindings environment. A TREE_LIST where each TREE_PURPOSE
948 is a parameter _DECL and the TREE_VALUE is the value of the parameter.
949 Note: This arrangement is made to accommodate the use of
950 iterative_hash_template_arg (see pt.c). If you change this
951 representation, also change the hash calculation in
952 cxx_eval_call_expression. */
954 /* Result of the call.
955 NULL means the call is being evaluated.
956 error_mark_node means that the evaluation was erroneous;
957 otherwise, the actuall value of the call. */
959 /* The hash of this call; we remember it here to avoid having to
960 recalculate it when expanding the hash table. */
964 struct constexpr_call_hasher
: ggc_ptr_hash
<constexpr_call
>
966 static hashval_t
hash (constexpr_call
*);
967 static bool equal (constexpr_call
*, constexpr_call
*);
970 enum constexpr_switch_state
{
971 /* Used when processing a switch for the first time by cxx_eval_switch_expr
972 and default: label for that switch has not been seen yet. */
973 css_default_not_seen
,
974 /* Used when processing a switch for the first time by cxx_eval_switch_expr
975 and default: label for that switch has been seen already. */
977 /* Used when processing a switch for the second time by
978 cxx_eval_switch_expr, where default: label should match. */
979 css_default_processing
982 /* The constexpr expansion context. CALL is the current function
983 expansion, CTOR is the current aggregate initializer, OBJECT is the
984 object being initialized by CTOR, either a VAR_DECL or a _REF. VALUES
985 is a map of values of variables initialized within the expression. */
987 struct constexpr_ctx
{
988 /* The innermost call we're evaluating. */
989 constexpr_call
*call
;
990 /* Values for any temporaries or local variables within the
991 constant-expression. */
992 hash_map
<tree
,tree
> *values
;
993 /* SAVE_EXPRs that we've seen within the current LOOP_EXPR. NULL if we
994 aren't inside a loop. */
995 hash_set
<tree
> *save_exprs
;
996 /* The CONSTRUCTOR we're currently building up for an aggregate
999 /* The object we're building the CONSTRUCTOR for. */
1001 /* If inside SWITCH_EXPR. */
1002 constexpr_switch_state
*css_state
;
1003 /* Whether we should error on a non-constant expression or fail quietly. */
1005 /* Whether we are strictly conforming to constant expression rules or
1006 trying harder to get a constant value. */
1010 /* A table of all constexpr calls that have been evaluated by the
1011 compiler in this translation unit. */
1013 static GTY (()) hash_table
<constexpr_call_hasher
> *constexpr_call_table
;
1015 static tree
cxx_eval_constant_expression (const constexpr_ctx
*, tree
,
1016 bool, bool *, bool *, tree
* = NULL
);
1018 /* Compute a hash value for a constexpr call representation. */
1021 constexpr_call_hasher::hash (constexpr_call
*info
)
1026 /* Return true if the objects pointed to by P and Q represent calls
1027 to the same constexpr function with the same arguments.
1028 Otherwise, return false. */
1031 constexpr_call_hasher::equal (constexpr_call
*lhs
, constexpr_call
*rhs
)
1037 if (lhs
->hash
!= rhs
->hash
)
1039 if (!constexpr_fundef_hasher::equal (lhs
->fundef
, rhs
->fundef
))
1041 lhs_bindings
= lhs
->bindings
;
1042 rhs_bindings
= rhs
->bindings
;
1043 while (lhs_bindings
!= NULL
&& rhs_bindings
!= NULL
)
1045 tree lhs_arg
= TREE_VALUE (lhs_bindings
);
1046 tree rhs_arg
= TREE_VALUE (rhs_bindings
);
1047 gcc_assert (TREE_TYPE (lhs_arg
) == TREE_TYPE (rhs_arg
));
1048 if (!cp_tree_equal (lhs_arg
, rhs_arg
))
1050 lhs_bindings
= TREE_CHAIN (lhs_bindings
);
1051 rhs_bindings
= TREE_CHAIN (rhs_bindings
);
1053 return lhs_bindings
== rhs_bindings
;
1056 /* Initialize the constexpr call table, if needed. */
1059 maybe_initialize_constexpr_call_table (void)
1061 if (constexpr_call_table
== NULL
)
1062 constexpr_call_table
= hash_table
<constexpr_call_hasher
>::create_ggc (101);
1065 /* During constexpr CALL_EXPR evaluation, to avoid issues with sharing when
1066 a function happens to get called recursively, we unshare the callee
1067 function's body and evaluate this unshared copy instead of evaluating the
1070 FUNDEF_COPIES_TABLE is a per-function freelist of these unshared function
1071 copies. The underlying data structure of FUNDEF_COPIES_TABLE is a hash_map
1072 that's keyed off of the original FUNCTION_DECL and whose value is a
1073 TREE_LIST of this function's unused copies awaiting reuse.
1075 This is not GC-deletable to avoid GC affecting UID generation. */
1077 static GTY(()) hash_map
<tree
, tree
> *fundef_copies_table
;
1079 /* Initialize FUNDEF_COPIES_TABLE if it's not initialized. */
1082 maybe_initialize_fundef_copies_table ()
1084 if (fundef_copies_table
== NULL
)
1085 fundef_copies_table
= hash_map
<tree
,tree
>::create_ggc (101);
1088 /* Reuse a copy or create a new unshared copy of the function FUN.
1089 Return this copy. We use a TREE_LIST whose PURPOSE is body, VALUE
1090 is parms, TYPE is result. */
1093 get_fundef_copy (tree fun
)
1095 maybe_initialize_fundef_copies_table ();
1099 tree
*slot
= &fundef_copies_table
->get_or_insert (fun
, &existed
);
1103 /* There is no cached function available, or in use. We can use
1104 the function directly. That the slot is now created records
1105 that this function is now in use. */
1106 copy
= build_tree_list (DECL_SAVED_TREE (fun
), DECL_ARGUMENTS (fun
));
1107 TREE_TYPE (copy
) = DECL_RESULT (fun
);
1109 else if (*slot
== NULL_TREE
)
1111 /* We've already used the function itself, so make a copy. */
1112 copy
= build_tree_list (NULL
, NULL
);
1113 TREE_PURPOSE (copy
) = copy_fn (fun
, TREE_VALUE (copy
), TREE_TYPE (copy
));
1117 /* We have a cached function available. */
1119 *slot
= TREE_CHAIN (copy
);
1125 /* Save the copy COPY of function FUN for later reuse by
1126 get_fundef_copy(). By construction, there will always be an entry
1130 save_fundef_copy (tree fun
, tree copy
)
1132 tree
*slot
= fundef_copies_table
->get (fun
);
1133 TREE_CHAIN (copy
) = *slot
;
1137 /* We have an expression tree T that represents a call, either CALL_EXPR
1138 or AGGR_INIT_EXPR. Return the Nth argument. */
1141 get_nth_callarg (tree t
, int n
)
1143 switch (TREE_CODE (t
))
1146 return CALL_EXPR_ARG (t
, n
);
1148 case AGGR_INIT_EXPR
:
1149 return AGGR_INIT_EXPR_ARG (t
, n
);
1157 /* Attempt to evaluate T which represents a call to a builtin function.
1158 We assume here that all builtin functions evaluate to scalar types
1159 represented by _CST nodes. */
1162 cxx_eval_builtin_function_call (const constexpr_ctx
*ctx
, tree t
, tree fun
,
1164 bool *non_constant_p
, bool *overflow_p
)
1166 const int nargs
= call_expr_nargs (t
);
1167 tree
*args
= (tree
*) alloca (nargs
* sizeof (tree
));
1171 /* Don't fold __builtin_constant_p within a constexpr function. */
1172 bool bi_const_p
= (DECL_FUNCTION_CODE (fun
) == BUILT_IN_CONSTANT_P
);
1174 /* If we aren't requiring a constant expression, defer __builtin_constant_p
1175 in a constexpr function until we have values for the parameters. */
1178 && current_function_decl
1179 && DECL_DECLARED_CONSTEXPR_P (current_function_decl
))
1181 *non_constant_p
= true;
1185 /* Be permissive for arguments to built-ins; __builtin_constant_p should
1186 return constant false for a non-constant argument. */
1187 constexpr_ctx new_ctx
= *ctx
;
1188 new_ctx
.quiet
= true;
1189 bool dummy1
= false, dummy2
= false;
1190 for (i
= 0; i
< nargs
; ++i
)
1192 args
[i
] = CALL_EXPR_ARG (t
, i
);
1193 /* If builtin_valid_in_constant_expr_p is true,
1194 potential_constant_expression_1 has not recursed into the arguments
1195 of the builtin, verify it here. */
1196 if (!builtin_valid_in_constant_expr_p (fun
)
1197 || potential_constant_expression (args
[i
]))
1198 args
[i
] = cxx_eval_constant_expression (&new_ctx
, args
[i
], false,
1201 /* For __built_in_constant_p, fold all expressions with constant values
1202 even if they aren't C++ constant-expressions. */
1203 args
[i
] = cp_fully_fold (args
[i
]);
1206 bool save_ffbcp
= force_folding_builtin_constant_p
;
1207 force_folding_builtin_constant_p
= true;
1208 new_call
= fold_builtin_call_array (EXPR_LOCATION (t
), TREE_TYPE (t
),
1209 CALL_EXPR_FN (t
), nargs
, args
);
1210 force_folding_builtin_constant_p
= save_ffbcp
;
1211 if (new_call
== NULL
)
1213 if (!*non_constant_p
&& !ctx
->quiet
)
1215 /* Do not allow__builtin_unreachable in constexpr function.
1216 The __builtin_unreachable call with BUILTINS_LOCATION
1217 comes from cp_maybe_instrument_return. */
1218 if (DECL_FUNCTION_CODE (fun
) == BUILT_IN_UNREACHABLE
1219 && EXPR_LOCATION (t
) == BUILTINS_LOCATION
)
1220 error ("%<constexpr%> call flows off the end of the function");
1223 new_call
= build_call_array_loc (EXPR_LOCATION (t
), TREE_TYPE (t
),
1224 CALL_EXPR_FN (t
), nargs
, args
);
1225 error ("%q+E is not a constant expression", new_call
);
1228 *non_constant_p
= true;
1232 if (!is_constant_expression (new_call
))
1234 if (!*non_constant_p
&& !ctx
->quiet
)
1235 error ("%q+E is not a constant expression", new_call
);
1236 *non_constant_p
= true;
1240 return cxx_eval_constant_expression (&new_ctx
, new_call
, lval
,
1241 non_constant_p
, overflow_p
);
1244 /* TEMP is the constant value of a temporary object of type TYPE. Adjust
1245 the type of the value to match. */
1248 adjust_temp_type (tree type
, tree temp
)
1250 if (TREE_TYPE (temp
) == type
)
1252 /* Avoid wrapping an aggregate value in a NOP_EXPR. */
1253 if (TREE_CODE (temp
) == CONSTRUCTOR
)
1254 return build_constructor (type
, CONSTRUCTOR_ELTS (temp
));
1255 gcc_assert (scalarish_type_p (type
));
1256 return cp_fold_convert (type
, temp
);
1259 /* Callback for walk_tree used by unshare_constructor. */
1262 find_constructor (tree
*tp
, int *walk_subtrees
, void *)
1266 if (TREE_CODE (*tp
) == CONSTRUCTOR
)
1271 /* If T is a CONSTRUCTOR or an expression that has a CONSTRUCTOR node as a
1272 subexpression, return an unshared copy of T. Otherwise return T. */
1275 unshare_constructor (tree t
)
1277 tree ctor
= walk_tree (&t
, find_constructor
, NULL
, NULL
);
1278 if (ctor
!= NULL_TREE
)
1279 return unshare_expr (t
);
1283 /* Subroutine of cxx_eval_call_expression.
1284 We are processing a call expression (either CALL_EXPR or
1285 AGGR_INIT_EXPR) in the context of CTX. Evaluate
1286 all arguments and bind their values to correspondings
1287 parameters, making up the NEW_CALL context. */
1290 cxx_bind_parameters_in_call (const constexpr_ctx
*ctx
, tree t
,
1291 constexpr_call
*new_call
,
1292 bool *non_constant_p
, bool *overflow_p
,
1293 bool *non_constant_args
)
1295 const int nargs
= call_expr_nargs (t
);
1296 tree fun
= new_call
->fundef
->decl
;
1297 tree parms
= DECL_ARGUMENTS (fun
);
1299 tree
*p
= &new_call
->bindings
;
1300 for (i
= 0; i
< nargs
; ++i
)
1303 tree type
= parms
? TREE_TYPE (parms
) : void_type_node
;
1304 x
= get_nth_callarg (t
, i
);
1305 /* For member function, the first argument is a pointer to the implied
1306 object. For a constructor, it might still be a dummy object, in
1307 which case we get the real argument from ctx. */
1308 if (i
== 0 && DECL_CONSTRUCTOR_P (fun
)
1309 && is_dummy_object (x
))
1312 x
= build_address (x
);
1314 arg
= cxx_eval_constant_expression (ctx
, x
, /*lval=*/false,
1315 non_constant_p
, overflow_p
);
1316 /* Don't VERIFY_CONSTANT here. */
1317 if (*non_constant_p
&& ctx
->quiet
)
1319 /* Just discard ellipsis args after checking their constantitude. */
1323 if (!*non_constant_p
)
1325 /* Don't share a CONSTRUCTOR that might be changed. */
1326 arg
= unshare_constructor (arg
);
1327 /* Make sure the binding has the same type as the parm. But
1328 only for constant args. */
1329 if (TREE_CODE (type
) != REFERENCE_TYPE
)
1330 arg
= adjust_temp_type (type
, arg
);
1331 if (!TREE_CONSTANT (arg
))
1332 *non_constant_args
= true;
1333 *p
= build_tree_list (parms
, arg
);
1334 p
= &TREE_CHAIN (*p
);
1336 parms
= TREE_CHAIN (parms
);
1340 /* Variables and functions to manage constexpr call expansion context.
1341 These do not need to be marked for PCH or GC. */
1343 /* FIXME remember and print actual constant arguments. */
1344 static vec
<tree
> call_stack
;
1345 static int call_stack_tick
;
1346 static int last_cx_error_tick
;
1349 push_cx_call_context (tree call
)
1352 if (!EXPR_HAS_LOCATION (call
))
1353 SET_EXPR_LOCATION (call
, input_location
);
1354 call_stack
.safe_push (call
);
1355 if (call_stack
.length () > (unsigned) max_constexpr_depth
)
1361 pop_cx_call_context (void)
1368 cx_error_context (void)
1370 vec
<tree
> r
= vNULL
;
1371 if (call_stack_tick
!= last_cx_error_tick
1372 && !call_stack
.is_empty ())
1374 last_cx_error_tick
= call_stack_tick
;
1378 /* Evaluate a call T to a GCC internal function when possible and return
1379 the evaluated result or, under the control of CTX, give an error, set
1380 NON_CONSTANT_P, and return the unevaluated call T otherwise. */
1383 cxx_eval_internal_function (const constexpr_ctx
*ctx
, tree t
,
1385 bool *non_constant_p
, bool *overflow_p
)
1387 enum tree_code opcode
= ERROR_MARK
;
1389 switch (CALL_EXPR_IFN (t
))
1391 case IFN_UBSAN_NULL
:
1392 case IFN_UBSAN_BOUNDS
:
1393 case IFN_UBSAN_VPTR
:
1394 case IFN_FALLTHROUGH
:
1397 case IFN_ADD_OVERFLOW
:
1400 case IFN_SUB_OVERFLOW
:
1401 opcode
= MINUS_EXPR
;
1403 case IFN_MUL_OVERFLOW
:
1408 return cxx_eval_constant_expression (ctx
, CALL_EXPR_ARG (t
, 0),
1409 false, non_constant_p
, overflow_p
);
1413 error_at (EXPR_LOC_OR_LOC (t
, input_location
),
1414 "call to internal function %qE", t
);
1415 *non_constant_p
= true;
1419 /* Evaluate constant arguments using OPCODE and return a complex
1420 number containing the result and the overflow bit. */
1421 tree arg0
= cxx_eval_constant_expression (ctx
, CALL_EXPR_ARG (t
, 0), lval
,
1422 non_constant_p
, overflow_p
);
1423 tree arg1
= cxx_eval_constant_expression (ctx
, CALL_EXPR_ARG (t
, 1), lval
,
1424 non_constant_p
, overflow_p
);
1426 if (TREE_CODE (arg0
) == INTEGER_CST
&& TREE_CODE (arg1
) == INTEGER_CST
)
1428 location_t loc
= EXPR_LOC_OR_LOC (t
, input_location
);
1429 tree type
= TREE_TYPE (TREE_TYPE (t
));
1430 tree result
= fold_binary_loc (loc
, opcode
, type
,
1431 fold_convert_loc (loc
, type
, arg0
),
1432 fold_convert_loc (loc
, type
, arg1
));
1434 = build_int_cst (type
, arith_overflowed_p (opcode
, type
, arg0
, arg1
));
1435 /* Reset TREE_OVERFLOW to avoid warnings for the overflow. */
1436 if (TREE_OVERFLOW (result
))
1437 TREE_OVERFLOW (result
) = 0;
1439 return build_complex (TREE_TYPE (t
), result
, ovf
);
1442 *non_constant_p
= true;
1446 /* Clean CONSTRUCTOR_NO_IMPLICIT_ZERO from CTOR and its sub-aggregates. */
1449 clear_no_implicit_zero (tree ctor
)
1451 if (CONSTRUCTOR_NO_IMPLICIT_ZERO (ctor
))
1453 CONSTRUCTOR_NO_IMPLICIT_ZERO (ctor
) = false;
1454 tree elt
; unsigned HOST_WIDE_INT idx
;
1455 FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (ctor
), idx
, elt
)
1456 if (TREE_CODE (elt
) == CONSTRUCTOR
)
1457 clear_no_implicit_zero (elt
);
1461 /* Subroutine of cxx_eval_constant_expression.
1462 Evaluate the call expression tree T in the context of OLD_CALL expression
1466 cxx_eval_call_expression (const constexpr_ctx
*ctx
, tree t
,
1468 bool *non_constant_p
, bool *overflow_p
)
1470 location_t loc
= EXPR_LOC_OR_LOC (t
, input_location
);
1471 tree fun
= get_function_named_in_call (t
);
1472 constexpr_call new_call
= { NULL
, NULL
, NULL
, 0 };
1475 if (fun
== NULL_TREE
)
1476 return cxx_eval_internal_function (ctx
, t
, lval
,
1477 non_constant_p
, overflow_p
);
1479 if (TREE_CODE (fun
) != FUNCTION_DECL
)
1481 /* Might be a constexpr function pointer. */
1482 fun
= cxx_eval_constant_expression (ctx
, fun
,
1483 /*lval*/false, non_constant_p
,
1486 if (TREE_CODE (fun
) == ADDR_EXPR
)
1487 fun
= TREE_OPERAND (fun
, 0);
1489 if (TREE_CODE (fun
) != FUNCTION_DECL
)
1491 if (!ctx
->quiet
&& !*non_constant_p
)
1492 error_at (loc
, "expression %qE does not designate a %<constexpr%> "
1494 *non_constant_p
= true;
1497 if (DECL_CLONED_FUNCTION_P (fun
))
1498 fun
= DECL_CLONED_FUNCTION (fun
);
1500 if (is_ubsan_builtin_p (fun
))
1503 if (is_builtin_fn (fun
))
1504 return cxx_eval_builtin_function_call (ctx
, t
, fun
,
1505 lval
, non_constant_p
, overflow_p
);
1506 if (!DECL_DECLARED_CONSTEXPR_P (fun
))
1510 if (!lambda_static_thunk_p (fun
))
1511 error_at (loc
, "call to non-%<constexpr%> function %qD", fun
);
1512 explain_invalid_constexpr_fn (fun
);
1514 *non_constant_p
= true;
1518 constexpr_ctx new_ctx
= *ctx
;
1519 if (DECL_CONSTRUCTOR_P (fun
) && !ctx
->object
1520 && TREE_CODE (t
) == AGGR_INIT_EXPR
)
1522 /* We want to have an initialization target for an AGGR_INIT_EXPR.
1523 If we don't already have one in CTX, use the AGGR_INIT_EXPR_SLOT. */
1524 new_ctx
.object
= AGGR_INIT_EXPR_SLOT (t
);
1525 tree ctor
= new_ctx
.ctor
= build_constructor (DECL_CONTEXT (fun
), NULL
);
1526 CONSTRUCTOR_NO_IMPLICIT_ZERO (ctor
) = true;
1527 ctx
->values
->put (new_ctx
.object
, ctor
);
1531 /* Shortcut trivial constructor/op=. */
1532 if (trivial_fn_p (fun
))
1534 tree init
= NULL_TREE
;
1535 if (call_expr_nargs (t
) == 2)
1536 init
= convert_from_reference (get_nth_callarg (t
, 1));
1537 else if (TREE_CODE (t
) == AGGR_INIT_EXPR
1538 && AGGR_INIT_ZERO_FIRST (t
))
1539 init
= build_zero_init (DECL_CONTEXT (fun
), NULL_TREE
, false);
1542 tree op
= get_nth_callarg (t
, 0);
1543 if (is_dummy_object (op
))
1546 op
= build1 (INDIRECT_REF
, TREE_TYPE (TREE_TYPE (op
)), op
);
1547 tree set
= build2 (MODIFY_EXPR
, TREE_TYPE (op
), op
, init
);
1548 new_ctx
.call
= &new_call
;
1549 return cxx_eval_constant_expression (&new_ctx
, set
, lval
,
1550 non_constant_p
, overflow_p
);
1554 /* We can't defer instantiating the function any longer. */
1555 if (!DECL_INITIAL (fun
)
1556 && DECL_TEMPLOID_INSTANTIATION (fun
))
1558 location_t save_loc
= input_location
;
1559 input_location
= loc
;
1561 instantiate_decl (fun
, /*defer_ok*/false, /*expl_inst*/false);
1563 input_location
= save_loc
;
1566 /* If in direct recursive call, optimize definition search. */
1567 if (ctx
&& ctx
->call
&& ctx
->call
->fundef
&& ctx
->call
->fundef
->decl
== fun
)
1568 new_call
.fundef
= ctx
->call
->fundef
;
1571 new_call
.fundef
= retrieve_constexpr_fundef (fun
);
1572 if (new_call
.fundef
== NULL
|| new_call
.fundef
->body
== NULL
1573 || fun
== current_function_decl
)
1577 /* We need to check for current_function_decl here in case we're
1578 being called during cp_fold_function, because at that point
1579 DECL_INITIAL is set properly and we have a fundef but we
1580 haven't lowered invisirefs yet (c++/70344). */
1581 if (DECL_INITIAL (fun
) == error_mark_node
1582 || fun
== current_function_decl
)
1583 error_at (loc
, "%qD called in a constant expression before its "
1584 "definition is complete", fun
);
1585 else if (DECL_INITIAL (fun
))
1587 /* The definition of fun was somehow unsuitable. But pretend
1588 that lambda static thunks don't exist. */
1589 if (!lambda_static_thunk_p (fun
))
1590 error_at (loc
, "%qD called in a constant expression", fun
);
1591 explain_invalid_constexpr_fn (fun
);
1594 error_at (loc
, "%qD used before its definition", fun
);
1596 *non_constant_p
= true;
1601 bool non_constant_args
= false;
1602 cxx_bind_parameters_in_call (ctx
, t
, &new_call
,
1603 non_constant_p
, overflow_p
, &non_constant_args
);
1604 if (*non_constant_p
)
1607 depth_ok
= push_cx_call_context (t
);
1609 tree result
= NULL_TREE
;
1611 constexpr_call
*entry
= NULL
;
1612 if (depth_ok
&& !non_constant_args
&& ctx
->strict
)
1614 new_call
.hash
= iterative_hash_template_arg
1615 (new_call
.bindings
, constexpr_fundef_hasher::hash (new_call
.fundef
));
1617 /* If we have seen this call before, we are done. */
1618 maybe_initialize_constexpr_call_table ();
1619 constexpr_call
**slot
1620 = constexpr_call_table
->find_slot (&new_call
, INSERT
);
1624 /* We need to keep a pointer to the entry, not just the slot, as the
1625 slot can move in the call to cxx_eval_builtin_function_call. */
1626 *slot
= entry
= ggc_alloc
<constexpr_call
> ();
1629 /* Calls that are in progress have their result set to NULL,
1630 so that we can detect circular dependencies. */
1631 else if (entry
->result
== NULL
)
1634 error ("call has circular dependency");
1635 *non_constant_p
= true;
1636 entry
->result
= result
= error_mark_node
;
1639 result
= entry
->result
;
1645 error ("%<constexpr%> evaluation depth exceeds maximum of %d (use "
1646 "-fconstexpr-depth= to increase the maximum)",
1647 max_constexpr_depth
);
1648 *non_constant_p
= true;
1649 result
= error_mark_node
;
1653 if (result
&& result
!= error_mark_node
)
1655 else if (!DECL_SAVED_TREE (fun
))
1657 /* When at_eof >= 2, cgraph has started throwing away
1658 DECL_SAVED_TREE, so fail quietly. FIXME we get here because of
1659 late code generation for VEC_INIT_EXPR, which needs to be
1660 completely reconsidered. */
1661 gcc_assert (at_eof
>= 2 && ctx
->quiet
);
1662 *non_constant_p
= true;
1666 tree body
, parms
, res
;
1668 /* Reuse or create a new unshared copy of this function's body. */
1669 tree copy
= get_fundef_copy (fun
);
1670 body
= TREE_PURPOSE (copy
);
1671 parms
= TREE_VALUE (copy
);
1672 res
= TREE_TYPE (copy
);
1674 /* Associate the bindings with the remapped parms. */
1675 tree bound
= new_call
.bindings
;
1676 tree remapped
= parms
;
1679 tree oparm
= TREE_PURPOSE (bound
);
1680 tree arg
= TREE_VALUE (bound
);
1681 gcc_assert (DECL_NAME (remapped
) == DECL_NAME (oparm
));
1682 /* Don't share a CONSTRUCTOR that might be changed. */
1683 arg
= unshare_constructor (arg
);
1684 ctx
->values
->put (remapped
, arg
);
1685 bound
= TREE_CHAIN (bound
);
1686 remapped
= DECL_CHAIN (remapped
);
1688 /* Add the RESULT_DECL to the values map, too. */
1689 tree slot
= NULL_TREE
;
1690 if (DECL_BY_REFERENCE (res
))
1692 slot
= AGGR_INIT_EXPR_SLOT (t
);
1693 tree addr
= build_address (slot
);
1694 addr
= build_nop (TREE_TYPE (res
), addr
);
1695 ctx
->values
->put (res
, addr
);
1696 ctx
->values
->put (slot
, NULL_TREE
);
1699 ctx
->values
->put (res
, NULL_TREE
);
1701 /* Track the callee's evaluated SAVE_EXPRs so that we can forget
1702 their values after the call. */
1703 constexpr_ctx ctx_with_save_exprs
= *ctx
;
1704 hash_set
<tree
> save_exprs
;
1705 ctx_with_save_exprs
.save_exprs
= &save_exprs
;
1706 ctx_with_save_exprs
.call
= &new_call
;
1708 tree jump_target
= NULL_TREE
;
1709 cxx_eval_constant_expression (&ctx_with_save_exprs
, body
,
1710 lval
, non_constant_p
, overflow_p
,
1713 if (DECL_CONSTRUCTOR_P (fun
))
1714 /* This can be null for a subobject constructor call, in
1715 which case what we care about is the initialization
1716 side-effects rather than the value. We could get at the
1717 value by evaluating *this, but we don't bother; there's
1718 no need to put such a call in the hash table. */
1719 result
= lval
? ctx
->object
: ctx
->ctor
;
1720 else if (VOID_TYPE_P (TREE_TYPE (res
)))
1724 result
= *ctx
->values
->get (slot
? slot
: res
);
1725 if (result
== NULL_TREE
&& !*non_constant_p
)
1728 error ("%<constexpr%> call flows off the end "
1730 *non_constant_p
= true;
1734 /* Forget the saved values of the callee's SAVE_EXPRs. */
1735 for (hash_set
<tree
>::iterator iter
= save_exprs
.begin();
1736 iter
!= save_exprs
.end(); ++iter
)
1737 ctx_with_save_exprs
.values
->remove (*iter
);
1739 /* Remove the parms/result from the values map. Is it worth
1740 bothering to do this when the map itself is only live for
1741 one constexpr evaluation? If so, maybe also clear out
1742 other vars from call, maybe in BIND_EXPR handling? */
1743 ctx
->values
->remove (res
);
1745 ctx
->values
->remove (slot
);
1746 for (tree parm
= parms
; parm
; parm
= TREE_CHAIN (parm
))
1747 ctx
->values
->remove (parm
);
1749 /* Make the unshared function copy we used available for re-use. */
1750 save_fundef_copy (fun
, copy
);
1753 if (result
== error_mark_node
)
1754 *non_constant_p
= true;
1755 if (*non_constant_p
|| *overflow_p
)
1756 result
= error_mark_node
;
1760 entry
->result
= result
;
1763 /* The result of a constexpr function must be completely initialized. */
1764 if (TREE_CODE (result
) == CONSTRUCTOR
)
1765 clear_no_implicit_zero (result
);
1767 pop_cx_call_context ();
1768 return unshare_constructor (result
);
1771 /* FIXME speed this up, it's taking 16% of compile time on sieve testcase. */
1774 reduced_constant_expression_p (tree t
)
1779 switch (TREE_CODE (t
))
1782 /* Even if we can't lower this yet, it's constant. */
1786 /* And we need to handle PTRMEM_CST wrapped in a CONSTRUCTOR. */
1787 tree idx
, val
, field
; unsigned HOST_WIDE_INT i
;
1788 if (CONSTRUCTOR_NO_IMPLICIT_ZERO (t
))
1790 if (TREE_CODE (TREE_TYPE (t
)) == VECTOR_TYPE
)
1791 /* An initialized vector would have a VECTOR_CST. */
1794 field
= next_initializable_field (TYPE_FIELDS (TREE_TYPE (t
)));
1798 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (t
), i
, idx
, val
)
1800 /* If VAL is null, we're in the middle of initializing this
1802 if (!reduced_constant_expression_p (val
))
1808 field
= next_initializable_field (DECL_CHAIN (field
));
1813 else if (CONSTRUCTOR_NO_IMPLICIT_ZERO (t
))
1814 /* All the fields are initialized. */
1815 CONSTRUCTOR_NO_IMPLICIT_ZERO (t
) = false;
1819 /* FIXME are we calling this too much? */
1820 return initializer_constant_valid_p (t
, TREE_TYPE (t
)) != NULL_TREE
;
1824 /* Some expressions may have constant operands but are not constant
1825 themselves, such as 1/0. Call this function to check for that
1828 We only call this in places that require an arithmetic constant, not in
1829 places where we might have a non-constant expression that can be a
1830 component of a constant expression, such as the address of a constexpr
1831 variable that might be dereferenced later. */
1834 verify_constant (tree t
, bool allow_non_constant
, bool *non_constant_p
,
1837 if (!*non_constant_p
&& !reduced_constant_expression_p (t
))
1839 if (!allow_non_constant
)
1840 error ("%q+E is not a constant expression", t
);
1841 *non_constant_p
= true;
1843 if (TREE_OVERFLOW_P (t
))
1845 if (!allow_non_constant
)
1847 permerror (input_location
, "overflow in constant expression");
1848 /* If we're being permissive (and are in an enforcing
1849 context), ignore the overflow. */
1850 if (flag_permissive
)
1851 return *non_constant_p
;
1855 return *non_constant_p
;
1858 /* Check whether the shift operation with code CODE and type TYPE on LHS
1859 and RHS is undefined. If it is, give an error with an explanation,
1860 and return true; return false otherwise. */
1863 cxx_eval_check_shift_p (location_t loc
, const constexpr_ctx
*ctx
,
1864 enum tree_code code
, tree type
, tree lhs
, tree rhs
)
1866 if ((code
!= LSHIFT_EXPR
&& code
!= RSHIFT_EXPR
)
1867 || TREE_CODE (lhs
) != INTEGER_CST
1868 || TREE_CODE (rhs
) != INTEGER_CST
)
1871 tree lhstype
= TREE_TYPE (lhs
);
1872 unsigned HOST_WIDE_INT uprec
= TYPE_PRECISION (TREE_TYPE (lhs
));
1874 /* [expr.shift] The behavior is undefined if the right operand
1875 is negative, or greater than or equal to the length in bits
1876 of the promoted left operand. */
1877 if (tree_int_cst_sgn (rhs
) == -1)
1880 permerror (loc
, "right operand of shift expression %q+E is negative",
1881 build2_loc (loc
, code
, type
, lhs
, rhs
));
1882 return (!flag_permissive
|| ctx
->quiet
);
1884 if (compare_tree_int (rhs
, uprec
) >= 0)
1887 permerror (loc
, "right operand of shift expression %q+E is >= than "
1888 "the precision of the left operand",
1889 build2_loc (loc
, code
, type
, lhs
, rhs
));
1890 return (!flag_permissive
|| ctx
->quiet
);
1893 /* The value of E1 << E2 is E1 left-shifted E2 bit positions; [...]
1894 if E1 has a signed type and non-negative value, and E1x2^E2 is
1895 representable in the corresponding unsigned type of the result type,
1896 then that value, converted to the result type, is the resulting value;
1897 otherwise, the behavior is undefined. */
1898 if (code
== LSHIFT_EXPR
&& !TYPE_UNSIGNED (lhstype
)
1899 && (cxx_dialect
>= cxx11
))
1901 if (tree_int_cst_sgn (lhs
) == -1)
1905 "left operand of shift expression %q+E is negative",
1906 build2_loc (loc
, code
, type
, lhs
, rhs
));
1907 return (!flag_permissive
|| ctx
->quiet
);
1909 /* For signed x << y the following:
1910 (unsigned) x >> ((prec (lhs) - 1) - y)
1911 if > 1, is undefined. The right-hand side of this formula
1912 is the highest bit of the LHS that can be set (starting from 0),
1913 so that the shift doesn't overflow. We then right-shift the LHS
1914 to see whether any other bit is set making the original shift
1915 undefined -- the result is not representable in the corresponding
1917 tree t
= build_int_cst (unsigned_type_node
, uprec
- 1);
1918 t
= fold_build2 (MINUS_EXPR
, unsigned_type_node
, t
, rhs
);
1919 tree ulhs
= fold_convert (unsigned_type_for (lhstype
), lhs
);
1920 t
= fold_build2 (RSHIFT_EXPR
, TREE_TYPE (ulhs
), ulhs
, t
);
1921 if (tree_int_cst_lt (integer_one_node
, t
))
1924 permerror (loc
, "shift expression %q+E overflows",
1925 build2_loc (loc
, code
, type
, lhs
, rhs
));
1926 return (!flag_permissive
|| ctx
->quiet
);
1932 /* Subroutine of cxx_eval_constant_expression.
1933 Attempt to reduce the unary expression tree T to a compile time value.
1934 If successful, return the value. Otherwise issue a diagnostic
1935 and return error_mark_node. */
1938 cxx_eval_unary_expression (const constexpr_ctx
*ctx
, tree t
,
1940 bool *non_constant_p
, bool *overflow_p
)
1943 tree orig_arg
= TREE_OPERAND (t
, 0);
1944 tree arg
= cxx_eval_constant_expression (ctx
, orig_arg
, /*lval*/false,
1945 non_constant_p
, overflow_p
);
1946 VERIFY_CONSTANT (arg
);
1947 location_t loc
= EXPR_LOCATION (t
);
1948 enum tree_code code
= TREE_CODE (t
);
1949 tree type
= TREE_TYPE (t
);
1950 r
= fold_unary_loc (loc
, code
, type
, arg
);
1953 if (arg
== orig_arg
)
1956 r
= build1_loc (loc
, code
, type
, arg
);
1958 VERIFY_CONSTANT (r
);
1962 /* Helper function for cxx_eval_binary_expression. Try to optimize
1963 original POINTER_PLUS_EXPR T, LHS p+ RHS, return NULL_TREE if the
1964 generic folding should be used. */
1967 cxx_fold_pointer_plus_expression (const constexpr_ctx
*ctx
, tree t
,
1968 tree lhs
, tree rhs
, bool *non_constant_p
,
1972 if (TREE_CODE (lhs
) != ADDR_EXPR
)
1975 lhs
= TREE_OPERAND (lhs
, 0);
1977 /* &A[i] p+ j => &A[i + j] */
1978 if (TREE_CODE (lhs
) == ARRAY_REF
1979 && TREE_CODE (TREE_OPERAND (lhs
, 1)) == INTEGER_CST
1980 && TREE_CODE (rhs
) == INTEGER_CST
1981 && TYPE_SIZE_UNIT (TREE_TYPE (lhs
))
1982 && TREE_CODE (TYPE_SIZE_UNIT (TREE_TYPE (lhs
))) == INTEGER_CST
)
1984 tree orig_type
= TREE_TYPE (t
);
1985 location_t loc
= EXPR_LOCATION (t
);
1986 tree type
= TREE_TYPE (lhs
);
1988 t
= fold_convert_loc (loc
, ssizetype
, TREE_OPERAND (lhs
, 1));
1989 tree nelts
= array_type_nelts_top (TREE_TYPE (TREE_OPERAND (lhs
, 0)));
1990 nelts
= cxx_eval_constant_expression (ctx
, nelts
, false, non_constant_p
,
1992 if (*non_constant_p
)
1994 /* Don't fold an out-of-bound access. */
1995 if (!tree_int_cst_le (t
, nelts
))
1997 rhs
= cp_fold_convert (ssizetype
, rhs
);
1998 /* Don't fold if rhs can't be divided exactly by TYPE_SIZE_UNIT.
1999 constexpr int A[1]; ... (char *)&A[0] + 1 */
2000 if (!integer_zerop (fold_build2_loc (loc
, TRUNC_MOD_EXPR
, sizetype
,
2001 rhs
, TYPE_SIZE_UNIT (type
))))
2003 /* Make sure to treat the second operand of POINTER_PLUS_EXPR
2005 rhs
= fold_build2_loc (loc
, EXACT_DIV_EXPR
, ssizetype
, rhs
,
2006 TYPE_SIZE_UNIT (type
));
2007 t
= size_binop_loc (loc
, PLUS_EXPR
, rhs
, t
);
2008 t
= build4_loc (loc
, ARRAY_REF
, type
, TREE_OPERAND (lhs
, 0),
2009 t
, NULL_TREE
, NULL_TREE
);
2010 t
= cp_build_addr_expr (t
, tf_warning_or_error
);
2011 t
= cp_fold_convert (orig_type
, t
);
2012 return cxx_eval_constant_expression (ctx
, t
, /*lval*/false,
2013 non_constant_p
, overflow_p
);
2019 /* Subroutine of cxx_eval_constant_expression.
2020 Like cxx_eval_unary_expression, except for binary expressions. */
2023 cxx_eval_binary_expression (const constexpr_ctx
*ctx
, tree t
,
2025 bool *non_constant_p
, bool *overflow_p
)
2028 tree orig_lhs
= TREE_OPERAND (t
, 0);
2029 tree orig_rhs
= TREE_OPERAND (t
, 1);
2031 lhs
= cxx_eval_constant_expression (ctx
, orig_lhs
, /*lval*/false,
2032 non_constant_p
, overflow_p
);
2033 /* Don't VERIFY_CONSTANT here, it's unnecessary and will break pointer
2035 if (*non_constant_p
)
2037 rhs
= cxx_eval_constant_expression (ctx
, orig_rhs
, /*lval*/false,
2038 non_constant_p
, overflow_p
);
2039 if (*non_constant_p
)
2042 location_t loc
= EXPR_LOCATION (t
);
2043 enum tree_code code
= TREE_CODE (t
);
2044 tree type
= TREE_TYPE (t
);
2046 if (code
== EQ_EXPR
|| code
== NE_EXPR
)
2048 bool is_code_eq
= (code
== EQ_EXPR
);
2050 if (TREE_CODE (lhs
) == PTRMEM_CST
2051 && TREE_CODE (rhs
) == PTRMEM_CST
)
2052 r
= constant_boolean_node (cp_tree_equal (lhs
, rhs
) == is_code_eq
,
2054 else if ((TREE_CODE (lhs
) == PTRMEM_CST
2055 || TREE_CODE (rhs
) == PTRMEM_CST
)
2056 && (null_member_pointer_value_p (lhs
)
2057 || null_member_pointer_value_p (rhs
)))
2058 r
= constant_boolean_node (!is_code_eq
, type
);
2059 else if (TREE_CODE (lhs
) == PTRMEM_CST
)
2060 lhs
= cplus_expand_constant (lhs
);
2061 else if (TREE_CODE (rhs
) == PTRMEM_CST
)
2062 rhs
= cplus_expand_constant (rhs
);
2064 if (code
== POINTER_PLUS_EXPR
&& !*non_constant_p
2065 && integer_zerop (lhs
) && !integer_zerop (rhs
))
2068 error ("arithmetic involving a null pointer in %qE", lhs
);
2071 else if (code
== POINTER_PLUS_EXPR
)
2072 r
= cxx_fold_pointer_plus_expression (ctx
, t
, lhs
, rhs
, non_constant_p
,
2076 r
= fold_binary_loc (loc
, code
, type
, lhs
, rhs
);
2080 if (lhs
== orig_lhs
&& rhs
== orig_rhs
)
2083 r
= build2_loc (loc
, code
, type
, lhs
, rhs
);
2085 else if (cxx_eval_check_shift_p (loc
, ctx
, code
, type
, lhs
, rhs
))
2086 *non_constant_p
= true;
2087 /* Don't VERIFY_CONSTANT if this might be dealing with a pointer to
2088 a local array in a constexpr function. */
2089 bool ptr
= POINTER_TYPE_P (TREE_TYPE (lhs
));
2091 VERIFY_CONSTANT (r
);
2095 /* Subroutine of cxx_eval_constant_expression.
2096 Attempt to evaluate condition expressions. Dead branches are not
2100 cxx_eval_conditional_expression (const constexpr_ctx
*ctx
, tree t
,
2102 bool *non_constant_p
, bool *overflow_p
,
2105 tree val
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 0),
2107 non_constant_p
, overflow_p
);
2108 VERIFY_CONSTANT (val
);
2109 /* Don't VERIFY_CONSTANT the other operands. */
2110 if (integer_zerop (val
))
2111 return cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 2),
2113 non_constant_p
, overflow_p
,
2115 return cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 1),
2117 non_constant_p
, overflow_p
,
2121 /* Subroutine of cxx_eval_constant_expression.
2122 Attempt to evaluate vector condition expressions. Unlike
2123 cxx_eval_conditional_expression, VEC_COND_EXPR acts like a normal
2124 ternary arithmetics operation, where all 3 arguments have to be
2125 evaluated as constants and then folding computes the result from
2129 cxx_eval_vector_conditional_expression (const constexpr_ctx
*ctx
, tree t
,
2130 bool *non_constant_p
, bool *overflow_p
)
2132 tree arg1
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 0),
2134 non_constant_p
, overflow_p
);
2135 VERIFY_CONSTANT (arg1
);
2136 tree arg2
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 1),
2138 non_constant_p
, overflow_p
);
2139 VERIFY_CONSTANT (arg2
);
2140 tree arg3
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 2),
2142 non_constant_p
, overflow_p
);
2143 VERIFY_CONSTANT (arg3
);
2144 location_t loc
= EXPR_LOCATION (t
);
2145 tree type
= TREE_TYPE (t
);
2146 tree r
= fold_ternary_loc (loc
, VEC_COND_EXPR
, type
, arg1
, arg2
, arg3
);
2149 if (arg1
== TREE_OPERAND (t
, 0)
2150 && arg2
== TREE_OPERAND (t
, 1)
2151 && arg3
== TREE_OPERAND (t
, 2))
2154 r
= build3_loc (loc
, VEC_COND_EXPR
, type
, arg1
, arg2
, arg3
);
2156 VERIFY_CONSTANT (r
);
2160 /* Returns less than, equal to, or greater than zero if KEY is found to be
2161 less than, to match, or to be greater than the constructor_elt's INDEX. */
2164 array_index_cmp (tree key
, tree index
)
2166 gcc_assert (TREE_CODE (key
) == INTEGER_CST
);
2168 switch (TREE_CODE (index
))
2171 return tree_int_cst_compare (key
, index
);
2174 tree lo
= TREE_OPERAND (index
, 0);
2175 tree hi
= TREE_OPERAND (index
, 1);
2176 if (tree_int_cst_lt (key
, lo
))
2178 else if (tree_int_cst_lt (hi
, key
))
2188 /* Returns the index of the constructor_elt of ARY which matches DINDEX, or -1
2189 if none. If INSERT is true, insert a matching element rather than fail. */
2191 static HOST_WIDE_INT
2192 find_array_ctor_elt (tree ary
, tree dindex
, bool insert
= false)
2194 if (tree_int_cst_sgn (dindex
) < 0)
2197 unsigned HOST_WIDE_INT i
= tree_to_uhwi (dindex
);
2198 vec
<constructor_elt
, va_gc
> *elts
= CONSTRUCTOR_ELTS (ary
);
2199 unsigned HOST_WIDE_INT len
= vec_safe_length (elts
);
2201 unsigned HOST_WIDE_INT end
= len
;
2202 unsigned HOST_WIDE_INT begin
= 0;
2204 /* If the last element of the CONSTRUCTOR has its own index, we can assume
2205 that the same is true of the other elements and index directly. */
2208 tree cindex
= (*elts
)[end
- 1].index
;
2209 if (TREE_CODE (cindex
) == INTEGER_CST
2210 && compare_tree_int (cindex
, end
- 1) == 0)
2219 /* Otherwise, find a matching index by means of a binary search. */
2220 while (begin
!= end
)
2222 unsigned HOST_WIDE_INT middle
= (begin
+ end
) / 2;
2223 constructor_elt
&elt
= (*elts
)[middle
];
2224 tree idx
= elt
.index
;
2226 int cmp
= array_index_cmp (dindex
, idx
);
2233 if (insert
&& TREE_CODE (idx
) == RANGE_EXPR
)
2235 /* We need to split the range. */
2237 tree lo
= TREE_OPERAND (idx
, 0);
2238 tree hi
= TREE_OPERAND (idx
, 1);
2239 tree value
= elt
.value
;
2240 dindex
= fold_convert (sizetype
, dindex
);
2241 if (tree_int_cst_lt (lo
, dindex
))
2243 /* There are still some lower elts; shorten the range. */
2244 tree new_hi
= int_const_binop (MINUS_EXPR
, dindex
,
2246 if (tree_int_cst_equal (lo
, new_hi
))
2247 /* Only one element left, no longer a range. */
2250 TREE_OPERAND (idx
, 1) = new_hi
;
2251 /* Append the element we want to insert. */
2254 e
.value
= unshare_constructor (value
);
2255 vec_safe_insert (CONSTRUCTOR_ELTS (ary
), middle
, e
);
2258 /* No lower elts, the range elt is now ours. */
2261 if (tree_int_cst_lt (dindex
, hi
))
2263 /* There are still some higher elts; append a range. */
2264 tree new_lo
= int_const_binop (PLUS_EXPR
, dindex
,
2266 if (tree_int_cst_equal (new_lo
, hi
))
2269 e
.index
= build2 (RANGE_EXPR
, sizetype
, new_lo
, hi
);
2270 e
.value
= unshare_constructor (value
);
2271 vec_safe_insert (CONSTRUCTOR_ELTS (ary
), middle
+ 1, e
);
2280 constructor_elt e
= { dindex
, NULL_TREE
};
2281 vec_safe_insert (CONSTRUCTOR_ELTS (ary
), end
, e
);
2288 /* Under the control of CTX, issue a detailed diagnostic for
2289 an out-of-bounds subscript INDEX into the expression ARRAY. */
2292 diag_array_subscript (const constexpr_ctx
*ctx
, tree array
, tree index
)
2296 tree arraytype
= TREE_TYPE (array
);
2298 /* Convert the unsigned array subscript to a signed integer to avoid
2299 printing huge numbers for small negative values. */
2300 tree sidx
= fold_convert (ssizetype
, index
);
2303 if (TYPE_DOMAIN (arraytype
))
2304 error ("array subscript value %qE is outside the bounds "
2305 "of array %qD of type %qT", sidx
, array
, arraytype
);
2307 error ("non-zero array subscript %qE is used with array %qD of "
2308 "type %qT with unknown bounds", sidx
, array
, arraytype
);
2309 inform (DECL_SOURCE_LOCATION (array
), "declared here");
2311 else if (TYPE_DOMAIN (arraytype
))
2312 error ("array subscript value %qE is outside the bounds "
2313 "of array type %qT", sidx
, arraytype
);
2315 error ("non-zero array subscript %qE is used with array of type %qT "
2316 "with unknown bounds", sidx
, arraytype
);
2320 /* Return the number of elements for TYPE (which is an ARRAY_TYPE or
2324 get_array_or_vector_nelts (const constexpr_ctx
*ctx
, tree type
,
2325 bool *non_constant_p
, bool *overflow_p
)
2328 if (TREE_CODE (type
) == ARRAY_TYPE
)
2330 if (TYPE_DOMAIN (type
))
2331 nelts
= array_type_nelts_top (type
);
2333 nelts
= size_zero_node
;
2335 else if (VECTOR_TYPE_P (type
))
2336 nelts
= size_int (TYPE_VECTOR_SUBPARTS (type
));
2340 /* For VLAs, the number of elements won't be an integer constant. */
2341 nelts
= cxx_eval_constant_expression (ctx
, nelts
, false,
2342 non_constant_p
, overflow_p
);
2346 /* Extract element INDEX consisting of CHARS_PER_ELT chars from
2347 STRING_CST STRING. */
2350 extract_string_elt (tree string
, unsigned chars_per_elt
, unsigned index
)
2352 tree type
= cv_unqualified (TREE_TYPE (TREE_TYPE (string
)));
2355 if (chars_per_elt
== 1)
2356 r
= build_int_cst (type
, TREE_STRING_POINTER (string
)[index
]);
2359 const unsigned char *ptr
2360 = ((const unsigned char *)TREE_STRING_POINTER (string
)
2361 + index
* chars_per_elt
);
2362 r
= native_interpret_expr (type
, ptr
, chars_per_elt
);
2367 /* Subroutine of cxx_eval_constant_expression.
2368 Attempt to reduce a reference to an array slot. */
2371 cxx_eval_array_reference (const constexpr_ctx
*ctx
, tree t
,
2373 bool *non_constant_p
, bool *overflow_p
)
2375 tree oldary
= TREE_OPERAND (t
, 0);
2376 tree ary
= cxx_eval_constant_expression (ctx
, oldary
,
2378 non_constant_p
, overflow_p
);
2380 HOST_WIDE_INT i
= 0;
2381 tree elem_type
= NULL_TREE
;
2382 unsigned len
= 0, elem_nchars
= 1;
2383 if (*non_constant_p
)
2385 oldidx
= TREE_OPERAND (t
, 1);
2386 index
= cxx_eval_constant_expression (ctx
, oldidx
,
2388 non_constant_p
, overflow_p
);
2389 VERIFY_CONSTANT (index
);
2392 elem_type
= TREE_TYPE (TREE_TYPE (ary
));
2393 if (TREE_CODE (ary
) == VIEW_CONVERT_EXPR
2394 && VECTOR_TYPE_P (TREE_TYPE (TREE_OPERAND (ary
, 0)))
2395 && TREE_TYPE (t
) == TREE_TYPE (TREE_TYPE (TREE_OPERAND (ary
, 0))))
2396 ary
= TREE_OPERAND (ary
, 0);
2397 if (TREE_CODE (ary
) == CONSTRUCTOR
)
2398 len
= CONSTRUCTOR_NELTS (ary
);
2399 else if (TREE_CODE (ary
) == STRING_CST
)
2401 elem_nchars
= (TYPE_PRECISION (elem_type
)
2402 / TYPE_PRECISION (char_type_node
));
2403 len
= (unsigned) TREE_STRING_LENGTH (ary
) / elem_nchars
;
2405 else if (TREE_CODE (ary
) == VECTOR_CST
)
2406 /* We don't create variable-length VECTOR_CSTs. */
2407 len
= VECTOR_CST_NELTS (ary
).to_constant ();
2410 /* We can't do anything with other tree codes, so use
2411 VERIFY_CONSTANT to complain and fail. */
2412 VERIFY_CONSTANT (ary
);
2416 if (!tree_fits_shwi_p (index
)
2417 || (i
= tree_to_shwi (index
)) < 0)
2419 diag_array_subscript (ctx
, ary
, index
);
2420 *non_constant_p
= true;
2425 tree nelts
= get_array_or_vector_nelts (ctx
, TREE_TYPE (ary
), non_constant_p
,
2427 VERIFY_CONSTANT (nelts
);
2429 ? !tree_int_cst_le (index
, nelts
)
2430 : !tree_int_cst_lt (index
, nelts
))
2431 || tree_int_cst_sgn (index
) < 0)
2433 diag_array_subscript (ctx
, ary
, index
);
2434 *non_constant_p
= true;
2438 if (lval
&& ary
== oldary
&& index
== oldidx
)
2441 return build4 (ARRAY_REF
, TREE_TYPE (t
), ary
, index
, NULL
, NULL
);
2444 if (TREE_CODE (ary
) == CONSTRUCTOR
)
2446 HOST_WIDE_INT ix
= find_array_ctor_elt (ary
, index
);
2457 if (TREE_CODE (ary
) == CONSTRUCTOR
)
2458 r
= (*CONSTRUCTOR_ELTS (ary
))[i
].value
;
2459 else if (TREE_CODE (ary
) == VECTOR_CST
)
2460 r
= VECTOR_CST_ELT (ary
, i
);
2462 r
= extract_string_elt (ary
, elem_nchars
, i
);
2465 /* Don't VERIFY_CONSTANT here. */
2468 /* Otherwise the element doesn't have a value yet. */
2473 if (TREE_CODE (ary
) == CONSTRUCTOR
2474 && CONSTRUCTOR_NO_IMPLICIT_ZERO (ary
))
2476 /* 'ary' is part of the aggregate initializer we're currently
2477 building; if there's no initializer for this element yet,
2480 error ("accessing uninitialized array element");
2481 *non_constant_p
= true;
2485 /* If it's within the array bounds but doesn't have an explicit
2486 initializer, it's value-initialized. */
2487 tree val
= build_value_init (elem_type
, tf_warning_or_error
);
2488 return cxx_eval_constant_expression (ctx
, val
, lval
, non_constant_p
,
2492 /* Subroutine of cxx_eval_constant_expression.
2493 Attempt to reduce a field access of a value of class type. */
2496 cxx_eval_component_reference (const constexpr_ctx
*ctx
, tree t
,
2498 bool *non_constant_p
, bool *overflow_p
)
2500 unsigned HOST_WIDE_INT i
;
2503 tree part
= TREE_OPERAND (t
, 1);
2504 tree orig_whole
= TREE_OPERAND (t
, 0);
2505 tree whole
= cxx_eval_constant_expression (ctx
, orig_whole
,
2507 non_constant_p
, overflow_p
);
2508 if (INDIRECT_REF_P (whole
)
2509 && integer_zerop (TREE_OPERAND (whole
, 0))
2511 error ("dereferencing a null pointer in %qE", orig_whole
);
2513 if (TREE_CODE (whole
) == PTRMEM_CST
)
2514 whole
= cplus_expand_constant (whole
);
2515 if (whole
== orig_whole
)
2518 return fold_build3 (COMPONENT_REF
, TREE_TYPE (t
),
2519 whole
, part
, NULL_TREE
);
2520 /* Don't VERIFY_CONSTANT here; we only want to check that we got a
2522 if (!*non_constant_p
&& TREE_CODE (whole
) != CONSTRUCTOR
)
2525 error ("%qE is not a constant expression", orig_whole
);
2526 *non_constant_p
= true;
2528 if (DECL_MUTABLE_P (part
))
2531 error ("mutable %qD is not usable in a constant expression", part
);
2532 *non_constant_p
= true;
2534 if (*non_constant_p
)
2536 bool pmf
= TYPE_PTRMEMFUNC_P (TREE_TYPE (whole
));
2537 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (whole
), i
, field
, value
)
2539 /* Use name match for PMF fields, as a variant will have a
2540 different FIELD_DECL with a different type. */
2541 if (pmf
? DECL_NAME (field
) == DECL_NAME (part
)
2547 /* We're in the middle of initializing it. */
2551 if (TREE_CODE (TREE_TYPE (whole
)) == UNION_TYPE
2552 && CONSTRUCTOR_NELTS (whole
) > 0)
2554 /* DR 1188 says we don't have to deal with this. */
2556 error ("accessing %qD member instead of initialized %qD member in "
2557 "constant expression", part
, CONSTRUCTOR_ELT (whole
, 0)->index
);
2558 *non_constant_p
= true;
2562 /* We only create a CONSTRUCTOR for a subobject when we modify it, so empty
2563 classes never get represented; throw together a value now. */
2564 if (is_really_empty_class (TREE_TYPE (t
)))
2565 return build_constructor (TREE_TYPE (t
), NULL
);
2567 gcc_assert (DECL_CONTEXT (part
) == TYPE_MAIN_VARIANT (TREE_TYPE (whole
)));
2569 if (CONSTRUCTOR_NO_IMPLICIT_ZERO (whole
))
2571 /* 'whole' is part of the aggregate initializer we're currently
2572 building; if there's no initializer for this member yet, that's an
2575 error ("accessing uninitialized member %qD", part
);
2576 *non_constant_p
= true;
2580 /* If there's no explicit init for this field, it's value-initialized. */
2581 value
= build_value_init (TREE_TYPE (t
), tf_warning_or_error
);
2582 return cxx_eval_constant_expression (ctx
, value
,
2584 non_constant_p
, overflow_p
);
2587 /* Subroutine of cxx_eval_constant_expression.
2588 Attempt to reduce a field access of a value of class type that is
2589 expressed as a BIT_FIELD_REF. */
2592 cxx_eval_bit_field_ref (const constexpr_ctx
*ctx
, tree t
,
2594 bool *non_constant_p
, bool *overflow_p
)
2596 tree orig_whole
= TREE_OPERAND (t
, 0);
2597 tree retval
, fldval
, utype
, mask
;
2598 bool fld_seen
= false;
2599 HOST_WIDE_INT istart
, isize
;
2600 tree whole
= cxx_eval_constant_expression (ctx
, orig_whole
,
2602 non_constant_p
, overflow_p
);
2603 tree start
, field
, value
;
2604 unsigned HOST_WIDE_INT i
;
2606 if (whole
== orig_whole
)
2608 /* Don't VERIFY_CONSTANT here; we only want to check that we got a
2610 if (!*non_constant_p
2611 && TREE_CODE (whole
) != VECTOR_CST
2612 && TREE_CODE (whole
) != CONSTRUCTOR
)
2615 error ("%qE is not a constant expression", orig_whole
);
2616 *non_constant_p
= true;
2618 if (*non_constant_p
)
2621 if (TREE_CODE (whole
) == VECTOR_CST
)
2622 return fold_ternary (BIT_FIELD_REF
, TREE_TYPE (t
), whole
,
2623 TREE_OPERAND (t
, 1), TREE_OPERAND (t
, 2));
2625 start
= TREE_OPERAND (t
, 2);
2626 istart
= tree_to_shwi (start
);
2627 isize
= tree_to_shwi (TREE_OPERAND (t
, 1));
2628 utype
= TREE_TYPE (t
);
2629 if (!TYPE_UNSIGNED (utype
))
2630 utype
= build_nonstandard_integer_type (TYPE_PRECISION (utype
), 1);
2631 retval
= build_int_cst (utype
, 0);
2632 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (whole
), i
, field
, value
)
2634 tree bitpos
= bit_position (field
);
2635 if (bitpos
== start
&& DECL_SIZE (field
) == TREE_OPERAND (t
, 1))
2637 if (TREE_CODE (TREE_TYPE (field
)) == INTEGER_TYPE
2638 && TREE_CODE (value
) == INTEGER_CST
2639 && tree_fits_shwi_p (bitpos
)
2640 && tree_fits_shwi_p (DECL_SIZE (field
)))
2642 HOST_WIDE_INT bit
= tree_to_shwi (bitpos
);
2643 HOST_WIDE_INT sz
= tree_to_shwi (DECL_SIZE (field
));
2644 HOST_WIDE_INT shift
;
2645 if (bit
>= istart
&& bit
+ sz
<= istart
+ isize
)
2647 fldval
= fold_convert (utype
, value
);
2648 mask
= build_int_cst_type (utype
, -1);
2649 mask
= fold_build2 (LSHIFT_EXPR
, utype
, mask
,
2650 size_int (TYPE_PRECISION (utype
) - sz
));
2651 mask
= fold_build2 (RSHIFT_EXPR
, utype
, mask
,
2652 size_int (TYPE_PRECISION (utype
) - sz
));
2653 fldval
= fold_build2 (BIT_AND_EXPR
, utype
, fldval
, mask
);
2654 shift
= bit
- istart
;
2655 if (BYTES_BIG_ENDIAN
)
2656 shift
= TYPE_PRECISION (utype
) - shift
- sz
;
2657 fldval
= fold_build2 (LSHIFT_EXPR
, utype
, fldval
,
2659 retval
= fold_build2 (BIT_IOR_EXPR
, utype
, retval
, fldval
);
2665 return fold_convert (TREE_TYPE (t
), retval
);
2667 return error_mark_node
;
2670 /* Subroutine of cxx_eval_constant_expression.
2671 Evaluate a short-circuited logical expression T in the context
2672 of a given constexpr CALL. BAILOUT_VALUE is the value for
2673 early return. CONTINUE_VALUE is used here purely for
2674 sanity check purposes. */
2677 cxx_eval_logical_expression (const constexpr_ctx
*ctx
, tree t
,
2678 tree bailout_value
, tree continue_value
,
2680 bool *non_constant_p
, bool *overflow_p
)
2683 tree lhs
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 0),
2685 non_constant_p
, overflow_p
);
2686 VERIFY_CONSTANT (lhs
);
2687 if (tree_int_cst_equal (lhs
, bailout_value
))
2689 gcc_assert (tree_int_cst_equal (lhs
, continue_value
));
2690 r
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 1),
2691 lval
, non_constant_p
,
2693 VERIFY_CONSTANT (r
);
2697 /* REF is a COMPONENT_REF designating a particular field. V is a vector of
2698 CONSTRUCTOR elements to initialize (part of) an object containing that
2699 field. Return a pointer to the constructor_elt corresponding to the
2700 initialization of the field. */
2702 static constructor_elt
*
2703 base_field_constructor_elt (vec
<constructor_elt
, va_gc
> *v
, tree ref
)
2705 tree aggr
= TREE_OPERAND (ref
, 0);
2706 tree field
= TREE_OPERAND (ref
, 1);
2708 constructor_elt
*ce
;
2710 gcc_assert (TREE_CODE (ref
) == COMPONENT_REF
);
2712 if (TREE_CODE (aggr
) == COMPONENT_REF
)
2714 constructor_elt
*base_ce
2715 = base_field_constructor_elt (v
, aggr
);
2716 v
= CONSTRUCTOR_ELTS (base_ce
->value
);
2719 for (i
= 0; vec_safe_iterate (v
, i
, &ce
); ++i
)
2720 if (ce
->index
== field
)
2727 /* Some of the expressions fed to the constexpr mechanism are calls to
2728 constructors, which have type void. In that case, return the type being
2729 initialized by the constructor. */
2732 initialized_type (tree t
)
2736 tree type
= cv_unqualified (TREE_TYPE (t
));
2737 if (TREE_CODE (t
) == CALL_EXPR
|| TREE_CODE (t
) == AGGR_INIT_EXPR
)
2739 /* A constructor call has void type, so we need to look deeper. */
2740 tree fn
= get_function_named_in_call (t
);
2741 if (fn
&& TREE_CODE (fn
) == FUNCTION_DECL
2742 && DECL_CXX_CONSTRUCTOR_P (fn
))
2743 type
= DECL_CONTEXT (fn
);
2748 /* We're about to initialize element INDEX of an array or class from VALUE.
2749 Set up NEW_CTX appropriately by adjusting .object to refer to the
2750 subobject and creating a new CONSTRUCTOR if the element is itself
2751 a class or array. */
2754 init_subob_ctx (const constexpr_ctx
*ctx
, constexpr_ctx
&new_ctx
,
2755 tree index
, tree
&value
)
2759 if (index
&& TREE_CODE (index
) != INTEGER_CST
2760 && TREE_CODE (index
) != FIELD_DECL
)
2761 /* This won't have an element in the new CONSTRUCTOR. */
2764 tree type
= initialized_type (value
);
2765 if (!AGGREGATE_TYPE_P (type
) && !VECTOR_TYPE_P (type
))
2766 /* A non-aggregate member doesn't get its own CONSTRUCTOR. */
2769 /* The sub-aggregate initializer might contain a placeholder;
2770 update object to refer to the subobject and ctor to refer to
2771 the (newly created) sub-initializer. */
2773 new_ctx
.object
= build_ctor_subob_ref (index
, type
, ctx
->object
);
2774 tree elt
= build_constructor (type
, NULL
);
2775 CONSTRUCTOR_NO_IMPLICIT_ZERO (elt
) = true;
2778 if (TREE_CODE (value
) == TARGET_EXPR
)
2779 /* Avoid creating another CONSTRUCTOR when we expand the TARGET_EXPR. */
2780 value
= TARGET_EXPR_INITIAL (value
);
2783 /* We're about to process an initializer for a class or array TYPE. Make
2784 sure that CTX is set up appropriately. */
2787 verify_ctor_sanity (const constexpr_ctx
*ctx
, tree type
)
2789 /* We don't bother building a ctor for an empty base subobject. */
2790 if (is_empty_class (type
))
2793 /* We're in the middle of an initializer that might involve placeholders;
2794 our caller should have created a CONSTRUCTOR for us to put the
2795 initializer into. We will either return that constructor or T. */
2796 gcc_assert (ctx
->ctor
);
2797 gcc_assert (same_type_ignoring_top_level_qualifiers_p
2798 (type
, TREE_TYPE (ctx
->ctor
)));
2799 /* We used to check that ctx->ctor was empty, but that isn't the case when
2800 the object is zero-initialized before calling the constructor. */
2803 tree otype
= TREE_TYPE (ctx
->object
);
2804 gcc_assert (same_type_ignoring_top_level_qualifiers_p (type
, otype
)
2805 /* Handle flexible array members. */
2806 || (TREE_CODE (otype
) == ARRAY_TYPE
2807 && TYPE_DOMAIN (otype
) == NULL_TREE
2808 && TREE_CODE (type
) == ARRAY_TYPE
2809 && (same_type_ignoring_top_level_qualifiers_p
2810 (TREE_TYPE (type
), TREE_TYPE (otype
)))));
2812 gcc_assert (!ctx
->object
|| !DECL_P (ctx
->object
)
2813 || *(ctx
->values
->get (ctx
->object
)) == ctx
->ctor
);
2816 /* Subroutine of cxx_eval_constant_expression.
2817 The expression tree T denotes a C-style array or a C-style
2818 aggregate. Reduce it to a constant expression. */
2821 cxx_eval_bare_aggregate (const constexpr_ctx
*ctx
, tree t
,
2823 bool *non_constant_p
, bool *overflow_p
)
2825 vec
<constructor_elt
, va_gc
> *v
= CONSTRUCTOR_ELTS (t
);
2826 bool changed
= false;
2827 gcc_assert (!BRACE_ENCLOSED_INITIALIZER_P (t
));
2828 tree type
= TREE_TYPE (t
);
2830 constexpr_ctx new_ctx
;
2831 if (TYPE_PTRMEMFUNC_P (type
) || VECTOR_TYPE_P (type
))
2833 /* We don't really need the ctx->ctor business for a PMF or
2834 vector, but it's simpler to use the same code. */
2836 new_ctx
.ctor
= build_constructor (type
, NULL
);
2837 new_ctx
.object
= NULL_TREE
;
2840 verify_ctor_sanity (ctx
, type
);
2841 vec
<constructor_elt
, va_gc
> **p
= &CONSTRUCTOR_ELTS (ctx
->ctor
);
2842 vec_alloc (*p
, vec_safe_length (v
));
2846 bool constant_p
= true;
2847 bool side_effects_p
= false;
2848 FOR_EACH_CONSTRUCTOR_ELT (v
, i
, index
, value
)
2850 tree orig_value
= value
;
2851 init_subob_ctx (ctx
, new_ctx
, index
, value
);
2852 if (new_ctx
.ctor
!= ctx
->ctor
)
2853 /* If we built a new CONSTRUCTOR, attach it now so that other
2854 initializers can refer to it. */
2855 CONSTRUCTOR_APPEND_ELT (*p
, index
, new_ctx
.ctor
);
2856 tree elt
= cxx_eval_constant_expression (&new_ctx
, value
,
2858 non_constant_p
, overflow_p
);
2859 /* Don't VERIFY_CONSTANT here. */
2860 if (ctx
->quiet
&& *non_constant_p
)
2862 if (elt
!= orig_value
)
2865 if (!TREE_CONSTANT (elt
))
2867 if (TREE_SIDE_EFFECTS (elt
))
2868 side_effects_p
= true;
2869 if (index
&& TREE_CODE (index
) == COMPONENT_REF
)
2871 /* This is an initialization of a vfield inside a base
2872 subaggregate that we already initialized; push this
2873 initialization into the previous initialization. */
2874 constructor_elt
*inner
= base_field_constructor_elt (*p
, index
);
2879 && (TREE_CODE (index
) == NOP_EXPR
2880 || TREE_CODE (index
) == POINTER_PLUS_EXPR
))
2882 /* This is an initializer for an empty base; now that we've
2883 checked that it's constant, we can ignore it. */
2884 gcc_assert (is_empty_class (TREE_TYPE (TREE_TYPE (index
))));
2889 if (new_ctx
.ctor
!= ctx
->ctor
)
2891 /* We appended this element above; update the value. */
2892 gcc_assert ((*p
)->last().index
== index
);
2893 (*p
)->last().value
= elt
;
2896 CONSTRUCTOR_APPEND_ELT (*p
, index
, elt
);
2897 /* Adding or replacing an element might change the ctor's flags. */
2898 TREE_CONSTANT (ctx
->ctor
) = constant_p
;
2899 TREE_SIDE_EFFECTS (ctx
->ctor
) = side_effects_p
;
2902 if (*non_constant_p
|| !changed
)
2905 /* We're done building this CONSTRUCTOR, so now we can interpret an
2906 element without an explicit initializer as value-initialized. */
2907 CONSTRUCTOR_NO_IMPLICIT_ZERO (t
) = false;
2908 TREE_CONSTANT (t
) = constant_p
;
2909 TREE_SIDE_EFFECTS (t
) = side_effects_p
;
2910 if (VECTOR_TYPE_P (type
))
2915 /* Subroutine of cxx_eval_constant_expression.
2916 The expression tree T is a VEC_INIT_EXPR which denotes the desired
2917 initialization of a non-static data member of array type. Reduce it to a
2920 Note that apart from value-initialization (when VALUE_INIT is true),
2921 this is only intended to support value-initialization and the
2922 initializations done by defaulted constructors for classes with
2923 non-static data members of array type. In this case, VEC_INIT_EXPR_INIT
2924 will either be NULL_TREE for the default constructor, or a COMPONENT_REF
2925 for the copy/move constructor. */
2928 cxx_eval_vec_init_1 (const constexpr_ctx
*ctx
, tree atype
, tree init
,
2929 bool value_init
, bool lval
,
2930 bool *non_constant_p
, bool *overflow_p
)
2932 tree elttype
= TREE_TYPE (atype
);
2933 verify_ctor_sanity (ctx
, atype
);
2934 vec
<constructor_elt
, va_gc
> **p
= &CONSTRUCTOR_ELTS (ctx
->ctor
);
2935 bool pre_init
= false;
2936 unsigned HOST_WIDE_INT i
;
2938 /* For the default constructor, build up a call to the default
2939 constructor of the element type. We only need to handle class types
2940 here, as for a constructor to be constexpr, all members must be
2941 initialized, which for a defaulted default constructor means they must
2942 be of a class type with a constexpr default constructor. */
2943 if (TREE_CODE (elttype
) == ARRAY_TYPE
)
2944 /* We only do this at the lowest level. */;
2945 else if (value_init
)
2947 init
= build_value_init (elttype
, tf_warning_or_error
);
2952 vec
<tree
, va_gc
> *argvec
= make_tree_vector ();
2953 init
= build_special_member_call (NULL_TREE
, complete_ctor_identifier
,
2954 &argvec
, elttype
, LOOKUP_NORMAL
,
2955 tf_warning_or_error
);
2956 release_tree_vector (argvec
);
2957 init
= build_aggr_init_expr (TREE_TYPE (init
), init
);
2961 tree nelts
= get_array_or_vector_nelts (ctx
, atype
, non_constant_p
,
2963 unsigned HOST_WIDE_INT max
= tree_to_uhwi (nelts
);
2964 for (i
= 0; i
< max
; ++i
)
2966 tree idx
= build_int_cst (size_type_node
, i
);
2969 constexpr_ctx new_ctx
;
2970 init_subob_ctx (ctx
, new_ctx
, idx
, pre_init
? init
: elttype
);
2971 if (new_ctx
.ctor
!= ctx
->ctor
)
2972 CONSTRUCTOR_APPEND_ELT (*p
, idx
, new_ctx
.ctor
);
2973 if (TREE_CODE (elttype
) == ARRAY_TYPE
)
2975 /* A multidimensional array; recurse. */
2976 if (value_init
|| init
== NULL_TREE
)
2978 eltinit
= NULL_TREE
;
2982 eltinit
= cp_build_array_ref (input_location
, init
, idx
,
2983 tf_warning_or_error
);
2984 eltinit
= cxx_eval_vec_init_1 (&new_ctx
, elttype
, eltinit
, value_init
,
2986 non_constant_p
, overflow_p
);
2990 /* Initializing an element using value or default initialization
2991 we just pre-built above. */
2992 eltinit
= cxx_eval_constant_expression (&new_ctx
, init
, lval
,
2993 non_constant_p
, overflow_p
);
2998 /* Copying an element. */
2999 gcc_assert (same_type_ignoring_top_level_qualifiers_p
3000 (atype
, TREE_TYPE (init
)));
3001 eltinit
= cp_build_array_ref (input_location
, init
, idx
,
3002 tf_warning_or_error
);
3003 if (!lvalue_p (init
))
3004 eltinit
= move (eltinit
);
3005 eltinit
= force_rvalue (eltinit
, tf_warning_or_error
);
3006 eltinit
= cxx_eval_constant_expression (&new_ctx
, eltinit
, lval
,
3007 non_constant_p
, overflow_p
);
3009 if (*non_constant_p
&& !ctx
->quiet
)
3011 if (new_ctx
.ctor
!= ctx
->ctor
)
3013 /* We appended this element above; update the value. */
3014 gcc_assert ((*p
)->last().index
== idx
);
3015 (*p
)->last().value
= eltinit
;
3018 CONSTRUCTOR_APPEND_ELT (*p
, idx
, eltinit
);
3019 /* Reuse the result of cxx_eval_constant_expression call
3020 from the first iteration to all others if it is a constant
3021 initializer that doesn't require relocations. */
3024 && (eltinit
== NULL_TREE
3025 || (initializer_constant_valid_p (eltinit
, TREE_TYPE (eltinit
))
3026 == null_pointer_node
)))
3028 if (new_ctx
.ctor
!= ctx
->ctor
)
3029 eltinit
= new_ctx
.ctor
;
3030 tree range
= build2 (RANGE_EXPR
, size_type_node
,
3031 build_int_cst (size_type_node
, 1),
3032 build_int_cst (size_type_node
, max
- 1));
3033 CONSTRUCTOR_APPEND_ELT (*p
, range
, unshare_constructor (eltinit
));
3037 vec_safe_reserve (*p
, max
);
3040 if (!*non_constant_p
)
3043 CONSTRUCTOR_NO_IMPLICIT_ZERO (init
) = false;
3049 cxx_eval_vec_init (const constexpr_ctx
*ctx
, tree t
,
3051 bool *non_constant_p
, bool *overflow_p
)
3053 tree atype
= TREE_TYPE (t
);
3054 tree init
= VEC_INIT_EXPR_INIT (t
);
3055 tree r
= cxx_eval_vec_init_1 (ctx
, atype
, init
,
3056 VEC_INIT_EXPR_VALUE_INIT (t
),
3057 lval
, non_constant_p
, overflow_p
);
3058 if (*non_constant_p
)
3064 /* A less strict version of fold_indirect_ref_1, which requires cv-quals to
3065 match. We want to be less strict for simple *& folding; if we have a
3066 non-const temporary that we access through a const pointer, that should
3067 work. We handle this here rather than change fold_indirect_ref_1
3068 because we're dealing with things like ADDR_EXPR of INTEGER_CST which
3069 don't really make sense outside of constant expression evaluation. Also
3070 we want to allow folding to COMPONENT_REF, which could cause trouble
3071 with TBAA in fold_indirect_ref_1.
3073 Try to keep this function synced with fold_indirect_ref_1. */
3076 cxx_fold_indirect_ref (location_t loc
, tree type
, tree op0
, bool *empty_base
)
3080 poly_uint64 const_op01
;
3083 subtype
= TREE_TYPE (sub
);
3084 if (!POINTER_TYPE_P (subtype
))
3087 if (TREE_CODE (sub
) == ADDR_EXPR
)
3089 tree op
= TREE_OPERAND (sub
, 0);
3090 tree optype
= TREE_TYPE (op
);
3092 /* *&CONST_DECL -> to the value of the const decl. */
3093 if (TREE_CODE (op
) == CONST_DECL
)
3094 return DECL_INITIAL (op
);
3095 /* *&p => p; make sure to handle *&"str"[cst] here. */
3096 if (same_type_ignoring_top_level_qualifiers_p (optype
, type
)
3097 /* Also handle the case where the desired type is an array of unknown
3098 bounds because the variable has had its bounds deduced since the
3099 ADDR_EXPR was created. */
3100 || (TREE_CODE (type
) == ARRAY_TYPE
3101 && TREE_CODE (optype
) == ARRAY_TYPE
3102 && TYPE_DOMAIN (type
) == NULL_TREE
3103 && same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (optype
),
3106 tree fop
= fold_read_from_constant_string (op
);
3112 /* *(foo *)&fooarray => fooarray[0] */
3113 else if (TREE_CODE (optype
) == ARRAY_TYPE
3114 && (same_type_ignoring_top_level_qualifiers_p
3115 (type
, TREE_TYPE (optype
))))
3117 tree type_domain
= TYPE_DOMAIN (optype
);
3118 tree min_val
= size_zero_node
;
3119 if (type_domain
&& TYPE_MIN_VALUE (type_domain
))
3120 min_val
= TYPE_MIN_VALUE (type_domain
);
3121 return build4_loc (loc
, ARRAY_REF
, type
, op
, min_val
,
3122 NULL_TREE
, NULL_TREE
);
3124 /* *(foo *)&complexfoo => __real__ complexfoo */
3125 else if (TREE_CODE (optype
) == COMPLEX_TYPE
3126 && (same_type_ignoring_top_level_qualifiers_p
3127 (type
, TREE_TYPE (optype
))))
3128 return fold_build1_loc (loc
, REALPART_EXPR
, type
, op
);
3129 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
3130 else if (VECTOR_TYPE_P (optype
)
3131 && (same_type_ignoring_top_level_qualifiers_p
3132 (type
, TREE_TYPE (optype
))))
3134 tree part_width
= TYPE_SIZE (type
);
3135 tree index
= bitsize_int (0);
3136 return fold_build3_loc (loc
, BIT_FIELD_REF
, type
, op
, part_width
,
3139 /* Also handle conversion to an empty base class, which
3140 is represented with a NOP_EXPR. */
3141 else if (is_empty_class (type
)
3142 && CLASS_TYPE_P (optype
)
3143 && DERIVED_FROM_P (type
, optype
))
3148 /* *(foo *)&struct_with_foo_field => COMPONENT_REF */
3149 else if (RECORD_OR_UNION_TYPE_P (optype
))
3151 tree field
= TYPE_FIELDS (optype
);
3152 for (; field
; field
= DECL_CHAIN (field
))
3153 if (TREE_CODE (field
) == FIELD_DECL
3154 && TREE_TYPE (field
) != error_mark_node
3155 && integer_zerop (byte_position (field
))
3156 && (same_type_ignoring_top_level_qualifiers_p
3157 (TREE_TYPE (field
), type
)))
3158 return fold_build3 (COMPONENT_REF
, type
, op
, field
, NULL_TREE
);
3161 else if (TREE_CODE (sub
) == POINTER_PLUS_EXPR
3162 && poly_int_tree_p (TREE_OPERAND (sub
, 1), &const_op01
))
3164 tree op00
= TREE_OPERAND (sub
, 0);
3165 tree op01
= TREE_OPERAND (sub
, 1);
3168 if (TREE_CODE (op00
) == ADDR_EXPR
)
3171 op00
= TREE_OPERAND (op00
, 0);
3172 op00type
= TREE_TYPE (op00
);
3174 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
3175 if (VECTOR_TYPE_P (op00type
)
3176 && same_type_ignoring_top_level_qualifiers_p
3177 (type
, TREE_TYPE (op00type
))
3178 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
3179 but we want to treat offsets with MSB set as negative.
3180 For the code below negative offsets are invalid and
3181 TYPE_SIZE of the element is something unsigned, so
3182 check whether op01 fits into poly_int64, which implies
3183 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
3184 then just use poly_uint64 because we want to treat the
3185 value as unsigned. */
3186 && tree_fits_poly_int64_p (op01
))
3188 tree part_width
= TYPE_SIZE (type
);
3189 poly_uint64 max_offset
3190 = (tree_to_uhwi (part_width
) / BITS_PER_UNIT
3191 * TYPE_VECTOR_SUBPARTS (op00type
));
3192 if (known_lt (const_op01
, max_offset
))
3194 tree index
= bitsize_int (const_op01
* BITS_PER_UNIT
);
3195 return fold_build3_loc (loc
,
3196 BIT_FIELD_REF
, type
, op00
,
3200 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
3201 else if (TREE_CODE (op00type
) == COMPLEX_TYPE
3202 && (same_type_ignoring_top_level_qualifiers_p
3203 (type
, TREE_TYPE (op00type
))))
3205 if (known_eq (wi::to_poly_offset (TYPE_SIZE_UNIT (type
)),
3207 return fold_build1_loc (loc
, IMAGPART_EXPR
, type
, op00
);
3209 /* ((foo *)&fooarray)[1] => fooarray[1] */
3210 else if (TREE_CODE (op00type
) == ARRAY_TYPE
3211 && (same_type_ignoring_top_level_qualifiers_p
3212 (type
, TREE_TYPE (op00type
))))
3214 tree type_domain
= TYPE_DOMAIN (op00type
);
3215 tree min_val
= size_zero_node
;
3216 if (type_domain
&& TYPE_MIN_VALUE (type_domain
))
3217 min_val
= TYPE_MIN_VALUE (type_domain
);
3218 offset_int off
= wi::to_offset (op01
);
3219 offset_int el_sz
= wi::to_offset (TYPE_SIZE_UNIT (type
));
3220 offset_int remainder
;
3221 off
= wi::divmod_trunc (off
, el_sz
, SIGNED
, &remainder
);
3222 if (remainder
== 0 && TREE_CODE (min_val
) == INTEGER_CST
)
3224 off
= off
+ wi::to_offset (min_val
);
3225 op01
= wide_int_to_tree (sizetype
, off
);
3226 return build4_loc (loc
, ARRAY_REF
, type
, op00
, op01
,
3227 NULL_TREE
, NULL_TREE
);
3230 /* Also handle conversion to an empty base class, which
3231 is represented with a NOP_EXPR. */
3232 else if (is_empty_class (type
)
3233 && CLASS_TYPE_P (op00type
)
3234 && DERIVED_FROM_P (type
, op00type
))
3239 /* ((foo *)&struct_with_foo_field)[1] => COMPONENT_REF */
3240 else if (RECORD_OR_UNION_TYPE_P (op00type
))
3242 tree field
= TYPE_FIELDS (op00type
);
3243 for (; field
; field
= DECL_CHAIN (field
))
3244 if (TREE_CODE (field
) == FIELD_DECL
3245 && TREE_TYPE (field
) != error_mark_node
3246 && tree_int_cst_equal (byte_position (field
), op01
)
3247 && (same_type_ignoring_top_level_qualifiers_p
3248 (TREE_TYPE (field
), type
)))
3249 return fold_build3 (COMPONENT_REF
, type
, op00
,
3254 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
3255 else if (TREE_CODE (TREE_TYPE (subtype
)) == ARRAY_TYPE
3256 && (same_type_ignoring_top_level_qualifiers_p
3257 (type
, TREE_TYPE (TREE_TYPE (subtype
)))))
3260 tree min_val
= size_zero_node
;
3262 = cxx_fold_indirect_ref (loc
, TREE_TYPE (subtype
), sub
, NULL
);
3266 sub
= build1_loc (loc
, INDIRECT_REF
, TREE_TYPE (subtype
), sub
);
3267 type_domain
= TYPE_DOMAIN (TREE_TYPE (sub
));
3268 if (type_domain
&& TYPE_MIN_VALUE (type_domain
))
3269 min_val
= TYPE_MIN_VALUE (type_domain
);
3270 return build4_loc (loc
, ARRAY_REF
, type
, sub
, min_val
, NULL_TREE
,
3278 cxx_eval_indirect_ref (const constexpr_ctx
*ctx
, tree t
,
3280 bool *non_constant_p
, bool *overflow_p
)
3282 tree orig_op0
= TREE_OPERAND (t
, 0);
3283 bool empty_base
= false;
3285 /* We can handle a MEM_REF like an INDIRECT_REF, if MEM_REF's second
3286 operand is an integer-zero. Otherwise reject the MEM_REF for now. */
3288 if (TREE_CODE (t
) == MEM_REF
3289 && (!TREE_OPERAND (t
, 1) || !integer_zerop (TREE_OPERAND (t
, 1))))
3291 gcc_assert (ctx
->quiet
);
3292 *non_constant_p
= true;
3296 /* First try to simplify it directly. */
3297 tree r
= cxx_fold_indirect_ref (EXPR_LOCATION (t
), TREE_TYPE (t
), orig_op0
,
3301 /* If that didn't work, evaluate the operand first. */
3302 tree op0
= cxx_eval_constant_expression (ctx
, orig_op0
,
3303 /*lval*/false, non_constant_p
,
3305 /* Don't VERIFY_CONSTANT here. */
3306 if (*non_constant_p
)
3309 if (!lval
&& integer_zerop (op0
))
3312 error ("dereferencing a null pointer");
3313 *non_constant_p
= true;
3317 r
= cxx_fold_indirect_ref (EXPR_LOCATION (t
), TREE_TYPE (t
), op0
,
3321 /* We couldn't fold to a constant value. Make sure it's not
3322 something we should have been able to fold. */
3325 if (TREE_CODE (sub
) == ADDR_EXPR
)
3327 gcc_assert (!same_type_ignoring_top_level_qualifiers_p
3328 (TREE_TYPE (TREE_TYPE (sub
)), TREE_TYPE (t
)));
3329 /* DR 1188 says we don't have to deal with this. */
3331 error ("accessing value of %qE through a %qT glvalue in a "
3332 "constant expression", build_fold_indirect_ref (sub
),
3334 *non_constant_p
= true;
3338 if (lval
&& op0
!= orig_op0
)
3339 return build1 (INDIRECT_REF
, TREE_TYPE (t
), op0
);
3341 VERIFY_CONSTANT (t
);
3346 r
= cxx_eval_constant_expression (ctx
, r
,
3347 lval
, non_constant_p
, overflow_p
);
3348 if (*non_constant_p
)
3351 /* If we're pulling out the value of an empty base, just return an empty
3353 if (empty_base
&& !lval
)
3355 r
= build_constructor (TREE_TYPE (t
), NULL
);
3356 TREE_CONSTANT (r
) = true;
3362 /* Complain about R, a VAR_DECL, not being usable in a constant expression.
3363 Shared between potential_constant_expression and
3364 cxx_eval_constant_expression. */
3367 non_const_var_error (tree r
)
3369 tree type
= TREE_TYPE (r
);
3370 error ("the value of %qD is not usable in a constant "
3372 /* Avoid error cascade. */
3373 if (DECL_INITIAL (r
) == error_mark_node
)
3375 if (DECL_DECLARED_CONSTEXPR_P (r
))
3376 inform (DECL_SOURCE_LOCATION (r
),
3377 "%qD used in its own initializer", r
);
3378 else if (INTEGRAL_OR_ENUMERATION_TYPE_P (type
))
3380 if (!CP_TYPE_CONST_P (type
))
3381 inform (DECL_SOURCE_LOCATION (r
),
3382 "%q#D is not const", r
);
3383 else if (CP_TYPE_VOLATILE_P (type
))
3384 inform (DECL_SOURCE_LOCATION (r
),
3385 "%q#D is volatile", r
);
3386 else if (!DECL_INITIAL (r
)
3387 || !TREE_CONSTANT (DECL_INITIAL (r
))
3388 || !DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (r
))
3389 inform (DECL_SOURCE_LOCATION (r
),
3390 "%qD was not initialized with a constant "
3395 else if (TREE_CODE (type
) == REFERENCE_TYPE
)
3396 inform (DECL_SOURCE_LOCATION (r
),
3397 "%qD was not initialized with a constant "
3401 if (cxx_dialect
>= cxx11
&& !DECL_DECLARED_CONSTEXPR_P (r
))
3402 inform (DECL_SOURCE_LOCATION (r
),
3403 "%qD was not declared %<constexpr%>", r
);
3405 inform (DECL_SOURCE_LOCATION (r
),
3406 "%qD does not have integral or enumeration type",
3411 /* Subroutine of cxx_eval_constant_expression.
3412 Like cxx_eval_unary_expression, except for trinary expressions. */
3415 cxx_eval_trinary_expression (const constexpr_ctx
*ctx
, tree t
,
3417 bool *non_constant_p
, bool *overflow_p
)
3423 for (i
= 0; i
< 3; i
++)
3425 args
[i
] = cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, i
),
3427 non_constant_p
, overflow_p
);
3428 VERIFY_CONSTANT (args
[i
]);
3431 val
= fold_ternary_loc (EXPR_LOCATION (t
), TREE_CODE (t
), TREE_TYPE (t
),
3432 args
[0], args
[1], args
[2]);
3433 if (val
== NULL_TREE
)
3435 VERIFY_CONSTANT (val
);
3439 /* True if T was declared in a function declared to be constexpr, and
3440 therefore potentially constant in C++14. */
3443 var_in_constexpr_fn (tree t
)
3445 tree ctx
= DECL_CONTEXT (t
);
3446 return (ctx
&& TREE_CODE (ctx
) == FUNCTION_DECL
3447 && DECL_DECLARED_CONSTEXPR_P (ctx
));
3450 /* True if T was declared in a function that might be constexpr: either a
3451 function that was declared constexpr, or a C++17 lambda op(). */
3454 var_in_maybe_constexpr_fn (tree t
)
3456 if (cxx_dialect
>= cxx17
3457 && DECL_FUNCTION_SCOPE_P (t
)
3458 && LAMBDA_FUNCTION_P (DECL_CONTEXT (t
)))
3460 return var_in_constexpr_fn (t
);
3463 /* We're assigning INIT to TARGET. In do_build_copy_constructor and
3464 build_over_call we implement trivial copy of a class with tail padding using
3465 assignment of character arrays, which is valid in normal code, but not in
3466 constexpr evaluation. We don't need to worry about clobbering tail padding
3467 in constexpr evaluation, so strip the type punning. */
3470 maybe_simplify_trivial_copy (tree
&target
, tree
&init
)
3472 if (TREE_CODE (target
) == MEM_REF
3473 && TREE_CODE (init
) == MEM_REF
3474 && TREE_TYPE (target
) == TREE_TYPE (init
)
3475 && TREE_CODE (TREE_TYPE (target
)) == ARRAY_TYPE
3476 && TREE_TYPE (TREE_TYPE (target
)) == unsigned_char_type_node
)
3478 target
= build_fold_indirect_ref (TREE_OPERAND (target
, 0));
3479 init
= build_fold_indirect_ref (TREE_OPERAND (init
, 0));
3483 /* Evaluate an INIT_EXPR or MODIFY_EXPR. */
3486 cxx_eval_store_expression (const constexpr_ctx
*ctx
, tree t
,
3488 bool *non_constant_p
, bool *overflow_p
)
3490 constexpr_ctx new_ctx
= *ctx
;
3492 tree init
= TREE_OPERAND (t
, 1);
3493 if (TREE_CLOBBER_P (init
))
3494 /* Just ignore clobbers. */
3497 /* First we figure out where we're storing to. */
3498 tree target
= TREE_OPERAND (t
, 0);
3500 maybe_simplify_trivial_copy (target
, init
);
3502 tree type
= TREE_TYPE (target
);
3503 target
= cxx_eval_constant_expression (ctx
, target
,
3505 non_constant_p
, overflow_p
);
3506 if (*non_constant_p
)
3509 /* cxx_eval_array_reference for lval = true allows references one past
3510 end of array, because it does not know if it is just taking address
3511 (which is valid), or actual dereference. Here we know it is
3512 a dereference, so diagnose it here. */
3513 for (tree probe
= target
; probe
; )
3515 switch (TREE_CODE (probe
))
3519 ary
= TREE_OPERAND (probe
, 0);
3520 nelts
= get_array_or_vector_nelts (ctx
, TREE_TYPE (ary
),
3521 non_constant_p
, overflow_p
);
3522 VERIFY_CONSTANT (nelts
);
3523 gcc_assert (TREE_CODE (nelts
) == INTEGER_CST
3524 && TREE_CODE (TREE_OPERAND (probe
, 1)) == INTEGER_CST
);
3525 if (wi::to_widest (TREE_OPERAND (probe
, 1)) == wi::to_widest (nelts
))
3527 diag_array_subscript (ctx
, ary
, TREE_OPERAND (probe
, 1));
3528 *non_constant_p
= true;
3535 probe
= TREE_OPERAND (probe
, 0);
3544 if (!same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (target
), type
))
3546 /* For initialization of an empty base, the original target will be
3547 *(base*)this, which the above evaluation resolves to the object
3548 argument, which has the derived type rather than the base type. In
3549 this situation, just evaluate the initializer and return, since
3550 there's no actual data to store. */
3551 gcc_assert (is_empty_class (type
));
3552 return cxx_eval_constant_expression (ctx
, init
, false,
3553 non_constant_p
, overflow_p
);
3556 /* And then find the underlying variable. */
3557 vec
<tree
,va_gc
> *refs
= make_tree_vector();
3558 tree object
= NULL_TREE
;
3559 for (tree probe
= target
; object
== NULL_TREE
; )
3561 switch (TREE_CODE (probe
))
3566 vec_safe_push (refs
, TREE_OPERAND (probe
, 1));
3567 vec_safe_push (refs
, TREE_TYPE (probe
));
3568 probe
= TREE_OPERAND (probe
, 0);
3576 /* And then find/build up our initializer for the path to the subobject
3577 we're initializing. */
3579 if (object
== ctx
->object
&& VAR_P (object
)
3580 && DECL_NAME (object
) && ctx
->call
== NULL
)
3581 /* The variable we're building up an aggregate initializer for is outside
3582 the constant-expression, so don't evaluate the store. We check
3583 DECL_NAME to handle TARGET_EXPR temporaries, which are fair game. */
3585 else if (DECL_P (object
))
3586 valp
= ctx
->values
->get (object
);
3591 /* A constant-expression cannot modify objects from outside the
3592 constant-expression. */
3594 error ("modification of %qE is not a constant expression", object
);
3595 *non_constant_p
= true;
3598 type
= TREE_TYPE (object
);
3599 bool no_zero_init
= true;
3601 vec
<tree
,va_gc
> *ctors
= make_tree_vector ();
3602 while (!refs
->is_empty())
3604 if (*valp
== NULL_TREE
)
3606 *valp
= build_constructor (type
, NULL
);
3607 CONSTRUCTOR_NO_IMPLICIT_ZERO (*valp
) = no_zero_init
;
3609 else if (TREE_CODE (*valp
) == STRING_CST
)
3611 /* An array was initialized with a string constant, and now
3612 we're writing into one of its elements. Explode the
3613 single initialization into a set of element
3615 gcc_assert (TREE_CODE (type
) == ARRAY_TYPE
);
3617 tree string
= *valp
;
3618 tree elt_type
= TREE_TYPE (type
);
3619 unsigned chars_per_elt
= (TYPE_PRECISION (elt_type
)
3620 / TYPE_PRECISION (char_type_node
));
3621 unsigned num_elts
= TREE_STRING_LENGTH (string
) / chars_per_elt
;
3622 tree ary_ctor
= build_constructor (type
, NULL
);
3624 vec_safe_reserve (CONSTRUCTOR_ELTS (ary_ctor
), num_elts
);
3625 for (unsigned ix
= 0; ix
!= num_elts
; ix
++)
3627 constructor_elt elt
=
3629 build_int_cst (size_type_node
, ix
),
3630 extract_string_elt (string
, chars_per_elt
, ix
)
3632 CONSTRUCTOR_ELTS (ary_ctor
)->quick_push (elt
);
3638 /* If the value of object is already zero-initialized, any new ctors for
3639 subobjects will also be zero-initialized. */
3640 no_zero_init
= CONSTRUCTOR_NO_IMPLICIT_ZERO (*valp
);
3642 vec_safe_push (ctors
, *valp
);
3644 enum tree_code code
= TREE_CODE (type
);
3646 tree index
= refs
->pop();
3648 constructor_elt
*cep
= NULL
;
3649 if (code
== ARRAY_TYPE
)
3652 = find_array_ctor_elt (*valp
, index
, /*insert*/true);
3653 gcc_assert (i
>= 0);
3654 cep
= CONSTRUCTOR_ELT (*valp
, i
);
3655 gcc_assert (TREE_CODE (cep
->index
) != RANGE_EXPR
);
3659 gcc_assert (TREE_CODE (index
) == FIELD_DECL
);
3661 /* We must keep the CONSTRUCTOR's ELTS in FIELD order.
3662 Usually we meet initializers in that order, but it is
3663 possible for base types to be placed not in program
3665 tree fields
= TYPE_FIELDS (DECL_CONTEXT (index
));
3666 unsigned HOST_WIDE_INT idx
;
3668 if (code
== UNION_TYPE
&& CONSTRUCTOR_NELTS (*valp
)
3669 && CONSTRUCTOR_ELT (*valp
, 0)->index
!= index
)
3670 /* Changing active member. */
3671 vec_safe_truncate (CONSTRUCTOR_ELTS (*valp
), 0);
3674 vec_safe_iterate (CONSTRUCTOR_ELTS (*valp
), idx
, &cep
);
3675 idx
++, fields
= DECL_CHAIN (fields
))
3677 if (index
== cep
->index
)
3680 /* The field we're initializing must be on the field
3681 list. Look to see if it is present before the
3682 field the current ELT initializes. */
3683 for (; fields
!= cep
->index
; fields
= DECL_CHAIN (fields
))
3684 if (index
== fields
)
3688 /* We fell off the end of the CONSTRUCTOR, so insert a new
3689 entry at the end. */
3692 constructor_elt ce
= { index
, NULL_TREE
};
3694 vec_safe_insert (CONSTRUCTOR_ELTS (*valp
), idx
, ce
);
3695 cep
= CONSTRUCTOR_ELT (*valp
, idx
);
3701 release_tree_vector (refs
);
3703 if (AGGREGATE_TYPE_P (type
) || VECTOR_TYPE_P (type
))
3705 /* Create a new CONSTRUCTOR in case evaluation of the initializer
3706 wants to modify it. */
3707 if (*valp
== NULL_TREE
)
3709 *valp
= build_constructor (type
, NULL
);
3710 CONSTRUCTOR_NO_IMPLICIT_ZERO (*valp
) = no_zero_init
;
3712 else if (TREE_CODE (*valp
) == PTRMEM_CST
)
3713 *valp
= cplus_expand_constant (*valp
);
3714 new_ctx
.ctor
= *valp
;
3715 new_ctx
.object
= target
;
3718 init
= cxx_eval_constant_expression (&new_ctx
, init
, false,
3719 non_constant_p
, overflow_p
);
3720 /* Don't share a CONSTRUCTOR that might be changed later. */
3721 init
= unshare_constructor (init
);
3722 if (target
== object
)
3723 /* The hash table might have moved since the get earlier. */
3724 valp
= ctx
->values
->get (object
);
3726 if (TREE_CODE (init
) == CONSTRUCTOR
)
3728 /* An outer ctx->ctor might be pointing to *valp, so replace
3730 CONSTRUCTOR_ELTS (*valp
) = CONSTRUCTOR_ELTS (init
);
3731 TREE_CONSTANT (*valp
) = TREE_CONSTANT (init
);
3732 TREE_SIDE_EFFECTS (*valp
) = TREE_SIDE_EFFECTS (init
);
3733 CONSTRUCTOR_NO_IMPLICIT_ZERO (*valp
)
3734 = CONSTRUCTOR_NO_IMPLICIT_ZERO (init
);
3739 /* Update TREE_CONSTANT and TREE_SIDE_EFFECTS on enclosing
3740 CONSTRUCTORs, if any. */
3743 bool c
= TREE_CONSTANT (init
);
3744 bool s
= TREE_SIDE_EFFECTS (init
);
3746 FOR_EACH_VEC_SAFE_ELT (ctors
, i
, elt
)
3749 TREE_CONSTANT (elt
) = false;
3751 TREE_SIDE_EFFECTS (elt
) = true;
3753 release_tree_vector (ctors
);
3755 if (*non_constant_p
)
3763 /* Evaluate a ++ or -- expression. */
3766 cxx_eval_increment_expression (const constexpr_ctx
*ctx
, tree t
,
3768 bool *non_constant_p
, bool *overflow_p
)
3770 enum tree_code code
= TREE_CODE (t
);
3771 tree type
= TREE_TYPE (t
);
3772 tree op
= TREE_OPERAND (t
, 0);
3773 tree offset
= TREE_OPERAND (t
, 1);
3774 gcc_assert (TREE_CONSTANT (offset
));
3776 /* The operand as an lvalue. */
3777 op
= cxx_eval_constant_expression (ctx
, op
, true,
3778 non_constant_p
, overflow_p
);
3780 /* The operand as an rvalue. */
3782 = cxx_eval_constant_expression (ctx
, op
, false,
3783 non_constant_p
, overflow_p
);
3784 /* Don't VERIFY_CONSTANT if this might be dealing with a pointer to
3785 a local array in a constexpr function. */
3786 bool ptr
= POINTER_TYPE_P (TREE_TYPE (val
));
3788 VERIFY_CONSTANT (val
);
3790 /* The modified value. */
3791 bool inc
= (code
== PREINCREMENT_EXPR
|| code
== POSTINCREMENT_EXPR
);
3793 if (POINTER_TYPE_P (type
))
3795 /* The middle end requires pointers to use POINTER_PLUS_EXPR. */
3796 offset
= convert_to_ptrofftype (offset
);
3798 offset
= fold_build1 (NEGATE_EXPR
, TREE_TYPE (offset
), offset
);
3799 mod
= fold_build2 (POINTER_PLUS_EXPR
, type
, val
, offset
);
3802 mod
= fold_build2 (inc
? PLUS_EXPR
: MINUS_EXPR
, type
, val
, offset
);
3804 VERIFY_CONSTANT (mod
);
3806 /* Storing the modified value. */
3807 tree store
= build2 (MODIFY_EXPR
, type
, op
, mod
);
3808 cxx_eval_constant_expression (ctx
, store
,
3809 true, non_constant_p
, overflow_p
);
3811 /* And the value of the expression. */
3812 if (code
== PREINCREMENT_EXPR
|| code
== PREDECREMENT_EXPR
)
3814 /* Prefix ops are lvalues. */
3818 /* But we optimize when the caller wants an rvalue. */
3822 /* Postfix ops are rvalues. */
3826 /* Predicates for the meaning of *jump_target. */
3829 returns (tree
*jump_target
)
3832 && (TREE_CODE (*jump_target
) == RETURN_EXPR
3833 || (TREE_CODE (*jump_target
) == LABEL_DECL
3834 && LABEL_DECL_CDTOR (*jump_target
)));
3838 breaks (tree
*jump_target
)
3841 && ((TREE_CODE (*jump_target
) == LABEL_DECL
3842 && LABEL_DECL_BREAK (*jump_target
))
3843 || TREE_CODE (*jump_target
) == EXIT_EXPR
);
3847 continues (tree
*jump_target
)
3850 && TREE_CODE (*jump_target
) == LABEL_DECL
3851 && LABEL_DECL_CONTINUE (*jump_target
);
3855 switches (tree
*jump_target
)
3858 && TREE_CODE (*jump_target
) == INTEGER_CST
;
3861 /* Subroutine of cxx_eval_statement_list. Determine whether the statement
3862 STMT matches *jump_target. If we're looking for a case label and we see
3863 the default label, note it in ctx->css_state. */
3866 label_matches (const constexpr_ctx
*ctx
, tree
*jump_target
, tree stmt
)
3868 switch (TREE_CODE (*jump_target
))
3871 if (TREE_CODE (stmt
) == LABEL_EXPR
3872 && LABEL_EXPR_LABEL (stmt
) == *jump_target
)
3877 if (TREE_CODE (stmt
) == CASE_LABEL_EXPR
)
3879 gcc_assert (ctx
->css_state
!= NULL
);
3880 if (!CASE_LOW (stmt
))
3882 /* default: should appear just once in a SWITCH_EXPR
3883 body (excluding nested SWITCH_EXPR). */
3884 gcc_assert (*ctx
->css_state
!= css_default_seen
);
3885 /* When evaluating SWITCH_EXPR body for the second time,
3886 return true for the default: label. */
3887 if (*ctx
->css_state
== css_default_processing
)
3889 *ctx
->css_state
= css_default_seen
;
3891 else if (CASE_HIGH (stmt
))
3893 if (tree_int_cst_le (CASE_LOW (stmt
), *jump_target
)
3894 && tree_int_cst_le (*jump_target
, CASE_HIGH (stmt
)))
3897 else if (tree_int_cst_equal (*jump_target
, CASE_LOW (stmt
)))
3908 /* Evaluate a STATEMENT_LIST for side-effects. Handles various jump
3909 semantics, for switch, break, continue, and return. */
3912 cxx_eval_statement_list (const constexpr_ctx
*ctx
, tree t
,
3913 bool *non_constant_p
, bool *overflow_p
,
3916 tree_stmt_iterator i
;
3918 /* In a statement-expression we want to return the last value.
3919 For empty statement expression return void_node. */
3923 local_target
= NULL_TREE
;
3924 jump_target
= &local_target
;
3926 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
3928 tree stmt
= tsi_stmt (i
);
3929 if (TREE_CODE (stmt
) == DEBUG_BEGIN_STMT
)
3931 r
= cxx_eval_constant_expression (ctx
, stmt
, false,
3932 non_constant_p
, overflow_p
,
3934 if (*non_constant_p
)
3936 if (returns (jump_target
) || breaks (jump_target
))
3942 /* Evaluate a LOOP_EXPR for side-effects. Handles break and return
3943 semantics; continue semantics are covered by cxx_eval_statement_list. */
3946 cxx_eval_loop_expr (const constexpr_ctx
*ctx
, tree t
,
3947 bool *non_constant_p
, bool *overflow_p
,
3950 constexpr_ctx new_ctx
= *ctx
;
3952 tree body
= TREE_OPERAND (t
, 0);
3956 hash_set
<tree
> save_exprs
;
3957 new_ctx
.save_exprs
= &save_exprs
;
3959 cxx_eval_constant_expression (&new_ctx
, body
, /*lval*/false,
3960 non_constant_p
, overflow_p
, jump_target
);
3962 /* Forget saved values of SAVE_EXPRs. */
3963 for (hash_set
<tree
>::iterator iter
= save_exprs
.begin();
3964 iter
!= save_exprs
.end(); ++iter
)
3965 new_ctx
.values
->remove (*iter
);
3966 if (++count
>= constexpr_loop_limit
)
3969 error_at (EXPR_LOC_OR_LOC (t
, input_location
),
3970 "%<constexpr%> loop iteration count exceeds limit of %d "
3971 "(use -fconstexpr-loop-limit= to increase the limit)",
3972 constexpr_loop_limit
);
3973 *non_constant_p
= true;
3977 while (!returns (jump_target
)
3978 && !breaks (jump_target
)
3979 && !switches (jump_target
)
3980 && !*non_constant_p
);
3982 if (breaks (jump_target
))
3983 *jump_target
= NULL_TREE
;
3988 /* Evaluate a SWITCH_EXPR for side-effects. Handles switch and break jump
3992 cxx_eval_switch_expr (const constexpr_ctx
*ctx
, tree t
,
3993 bool *non_constant_p
, bool *overflow_p
,
3996 tree cond
= TREE_OPERAND (t
, 0);
3997 cond
= cxx_eval_constant_expression (ctx
, cond
, false,
3998 non_constant_p
, overflow_p
);
3999 VERIFY_CONSTANT (cond
);
4000 *jump_target
= cond
;
4002 tree body
= TREE_OPERAND (t
, 1);
4003 constexpr_ctx new_ctx
= *ctx
;
4004 constexpr_switch_state css
= css_default_not_seen
;
4005 new_ctx
.css_state
= &css
;
4006 cxx_eval_constant_expression (&new_ctx
, body
, false,
4007 non_constant_p
, overflow_p
, jump_target
);
4008 if (switches (jump_target
) && css
== css_default_seen
)
4010 /* If the SWITCH_EXPR body has default: label, process it once again,
4011 this time instructing label_matches to return true for default:
4012 label on switches (jump_target). */
4013 css
= css_default_processing
;
4014 cxx_eval_constant_expression (&new_ctx
, body
, false,
4015 non_constant_p
, overflow_p
, jump_target
);
4017 if (breaks (jump_target
) || switches (jump_target
))
4018 *jump_target
= NULL_TREE
;
4022 /* Find the object of TYPE under initialization in CTX. */
4025 lookup_placeholder (const constexpr_ctx
*ctx
, bool lval
, tree type
)
4030 /* We could use ctx->object unconditionally, but using ctx->ctor when we
4031 can is a minor optimization. */
4032 if (!lval
&& ctx
->ctor
&& same_type_p (TREE_TYPE (ctx
->ctor
), type
))
4038 /* Since an object cannot have a field of its own type, we can search outward
4039 from ctx->object to find the unique containing object of TYPE. */
4040 tree ob
= ctx
->object
;
4043 if (same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (ob
), type
))
4045 if (handled_component_p (ob
))
4046 ob
= TREE_OPERAND (ob
, 0);
4054 /* Attempt to reduce the expression T to a constant value.
4055 On failure, issue diagnostic and return error_mark_node. */
4056 /* FIXME unify with c_fully_fold */
4057 /* FIXME overflow_p is too global */
4060 cxx_eval_constant_expression (const constexpr_ctx
*ctx
, tree t
,
4062 bool *non_constant_p
, bool *overflow_p
,
4065 constexpr_ctx new_ctx
;
4068 if (jump_target
&& *jump_target
)
4070 /* If we are jumping, ignore all statements/expressions except those
4071 that could have LABEL_EXPR or CASE_LABEL_EXPR in their bodies. */
4072 switch (TREE_CODE (t
))
4075 case STATEMENT_LIST
:
4080 case CASE_LABEL_EXPR
:
4081 if (label_matches (ctx
, jump_target
, t
))
4083 *jump_target
= NULL_TREE
;
4089 if (t
== error_mark_node
)
4091 *non_constant_p
= true;
4094 if (CONSTANT_CLASS_P (t
))
4096 if (TREE_OVERFLOW (t
))
4099 permerror (input_location
, "overflow in constant expression");
4100 if (!flag_permissive
|| ctx
->quiet
)
4104 if (TREE_CODE (t
) == INTEGER_CST
4105 && TREE_CODE (TREE_TYPE (t
)) == POINTER_TYPE
4106 && !integer_zerop (t
))
4109 error ("value %qE of type %qT is not a constant expression",
4111 *non_constant_p
= true;
4117 tree_code tcode
= TREE_CODE (t
);
4123 /* We ask for an rvalue for the RESULT_DECL when indirecting
4124 through an invisible reference, or in named return value
4126 if (tree
*p
= ctx
->values
->get (t
))
4131 error ("%qE is not a constant expression", t
);
4132 *non_constant_p
= true;
4137 if (DECL_HAS_VALUE_EXPR_P (t
))
4138 return cxx_eval_constant_expression (ctx
, DECL_VALUE_EXPR (t
),
4139 lval
, non_constant_p
, overflow_p
);
4142 /* We used to not check lval for CONST_DECL, but darwin.c uses
4143 CONST_DECL for aggregate constants. */
4146 if (COMPLETE_TYPE_P (TREE_TYPE (t
))
4147 && is_really_empty_class (TREE_TYPE (t
)))
4149 /* If the class is empty, we aren't actually loading anything. */
4150 r
= build_constructor (TREE_TYPE (t
), NULL
);
4151 TREE_CONSTANT (r
) = true;
4153 else if (ctx
->strict
)
4154 r
= decl_really_constant_value (t
);
4156 r
= decl_constant_value (t
);
4157 if (TREE_CODE (r
) == TARGET_EXPR
4158 && TREE_CODE (TARGET_EXPR_INITIAL (r
)) == CONSTRUCTOR
)
4159 r
= TARGET_EXPR_INITIAL (r
);
4161 if (tree
*p
= ctx
->values
->get (r
))
4162 if (*p
!= NULL_TREE
)
4167 non_const_var_error (r
);
4168 *non_constant_p
= true;
4172 case DEBUG_BEGIN_STMT
:
4173 /* ??? It might be nice to retain this information somehow, so
4174 as to be able to step into a constexpr function call. */
4181 case CASE_LABEL_EXPR
:
4186 if (lval
&& TREE_CODE (TREE_TYPE (t
)) != REFERENCE_TYPE
)
4188 else if (tree
*p
= ctx
->values
->get (r
))
4191 /* Defer in case this is only used for its type. */;
4192 else if (TREE_CODE (TREE_TYPE (t
)) == REFERENCE_TYPE
)
4193 /* Defer, there's no lvalue->rvalue conversion. */;
4194 else if (COMPLETE_TYPE_P (TREE_TYPE (t
))
4195 && is_really_empty_class (TREE_TYPE (t
)))
4197 /* If the class is empty, we aren't actually loading anything. */
4198 r
= build_constructor (TREE_TYPE (t
), NULL
);
4199 TREE_CONSTANT (r
) = true;
4204 error ("%qE is not a constant expression", t
);
4205 *non_constant_p
= true;
4210 case AGGR_INIT_EXPR
:
4211 r
= cxx_eval_call_expression (ctx
, t
, lval
,
4212 non_constant_p
, overflow_p
);
4217 r
= DECL_EXPR_DECL (t
);
4218 if (AGGREGATE_TYPE_P (TREE_TYPE (r
))
4219 || VECTOR_TYPE_P (TREE_TYPE (r
)))
4223 new_ctx
.ctor
= build_constructor (TREE_TYPE (r
), NULL
);
4224 CONSTRUCTOR_NO_IMPLICIT_ZERO (new_ctx
.ctor
) = true;
4225 new_ctx
.values
->put (r
, new_ctx
.ctor
);
4229 if (tree init
= DECL_INITIAL (r
))
4231 init
= cxx_eval_constant_expression (ctx
, init
,
4233 non_constant_p
, overflow_p
);
4234 /* Don't share a CONSTRUCTOR that might be changed. */
4235 init
= unshare_constructor (init
);
4236 ctx
->values
->put (r
, init
);
4238 else if (ctx
== &new_ctx
)
4239 /* We gave it a CONSTRUCTOR above. */;
4241 ctx
->values
->put (r
, NULL_TREE
);
4246 if (!literal_type_p (TREE_TYPE (t
)))
4250 error ("temporary of non-literal type %qT in a "
4251 "constant expression", TREE_TYPE (t
));
4252 explain_non_literal_class (TREE_TYPE (t
));
4254 *non_constant_p
= true;
4257 if ((AGGREGATE_TYPE_P (TREE_TYPE (t
)) || VECTOR_TYPE_P (TREE_TYPE (t
))))
4259 /* We're being expanded without an explicit target, so start
4260 initializing a new object; expansion with an explicit target
4261 strips the TARGET_EXPR before we get here. */
4263 new_ctx
.ctor
= build_constructor (TREE_TYPE (t
), NULL
);
4264 CONSTRUCTOR_NO_IMPLICIT_ZERO (new_ctx
.ctor
) = true;
4265 new_ctx
.object
= TARGET_EXPR_SLOT (t
);
4266 ctx
->values
->put (new_ctx
.object
, new_ctx
.ctor
);
4269 /* Pass false for 'lval' because this indicates
4270 initialization of a temporary. */
4271 r
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 1),
4273 non_constant_p
, overflow_p
);
4274 if (!*non_constant_p
)
4275 /* Adjust the type of the result to the type of the temporary. */
4276 r
= adjust_temp_type (TREE_TYPE (t
), r
);
4279 tree slot
= TARGET_EXPR_SLOT (t
);
4280 r
= unshare_constructor (r
);
4281 ctx
->values
->put (slot
, r
);
4288 gcc_assert (jump_target
== NULL
|| *jump_target
== NULL_TREE
);
4289 r
= cxx_eval_store_expression (ctx
, t
, lval
,
4290 non_constant_p
, overflow_p
);
4294 r
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 1),
4296 non_constant_p
, overflow_p
);
4300 if (TREE_OPERAND (t
, 0) != NULL_TREE
)
4301 r
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 0),
4303 non_constant_p
, overflow_p
);
4308 /* Can happen with ({ return true; }) && false; passed to
4309 maybe_constant_value. There is nothing to jump over in this
4310 case, and the bug will be diagnosed later. */
4311 gcc_assert (ctx
->quiet
);
4312 *non_constant_p
= true;
4317 /* Avoid evaluating a SAVE_EXPR more than once. */
4318 if (tree
*p
= ctx
->values
->get (t
))
4322 r
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 0), false,
4323 non_constant_p
, overflow_p
);
4324 ctx
->values
->put (t
, r
);
4325 if (ctx
->save_exprs
)
4326 ctx
->save_exprs
->add (t
);
4330 case NON_LVALUE_EXPR
:
4331 case TRY_CATCH_EXPR
:
4333 case CLEANUP_POINT_EXPR
:
4334 case MUST_NOT_THROW_EXPR
:
4337 r
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 0),
4339 non_constant_p
, overflow_p
,
4343 case TRY_FINALLY_EXPR
:
4344 r
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 0), lval
,
4345 non_constant_p
, overflow_p
,
4347 if (!*non_constant_p
)
4348 /* Also evaluate the cleanup. */
4349 cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 1), true,
4350 non_constant_p
, overflow_p
,
4354 /* These differ from cxx_eval_unary_expression in that this doesn't
4355 check for a constant operand or result; an address can be
4356 constant without its operand being, and vice versa. */
4359 r
= cxx_eval_indirect_ref (ctx
, t
, lval
,
4360 non_constant_p
, overflow_p
);
4365 tree oldop
= TREE_OPERAND (t
, 0);
4366 tree op
= cxx_eval_constant_expression (ctx
, oldop
,
4368 non_constant_p
, overflow_p
);
4369 /* Don't VERIFY_CONSTANT here. */
4370 if (*non_constant_p
)
4372 gcc_checking_assert (TREE_CODE (op
) != CONSTRUCTOR
);
4373 /* This function does more aggressive folding than fold itself. */
4374 r
= build_fold_addr_expr_with_type (op
, TREE_TYPE (t
));
4375 if (TREE_CODE (r
) == ADDR_EXPR
&& TREE_OPERAND (r
, 0) == oldop
)
4384 r
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 0), lval
,
4385 non_constant_p
, overflow_p
);
4386 if (r
== error_mark_node
)
4388 else if (r
== TREE_OPERAND (t
, 0))
4391 r
= fold_build1 (TREE_CODE (t
), TREE_TYPE (t
), r
);
4396 case FIX_TRUNC_EXPR
:
4401 case TRUTH_NOT_EXPR
:
4402 case FIXED_CONVERT_EXPR
:
4403 r
= cxx_eval_unary_expression (ctx
, t
, lval
,
4404 non_constant_p
, overflow_p
);
4408 r
= fold_sizeof_expr (t
);
4409 VERIFY_CONSTANT (r
);
4414 /* check_return_expr sometimes wraps a TARGET_EXPR in a
4415 COMPOUND_EXPR; don't get confused. Also handle EMPTY_CLASS_EXPR
4416 introduced by build_call_a. */
4417 tree op0
= TREE_OPERAND (t
, 0);
4418 tree op1
= TREE_OPERAND (t
, 1);
4420 if ((TREE_CODE (op0
) == TARGET_EXPR
&& op1
== TARGET_EXPR_SLOT (op0
))
4421 || TREE_CODE (op1
) == EMPTY_CLASS_EXPR
)
4422 r
= cxx_eval_constant_expression (ctx
, op0
,
4423 lval
, non_constant_p
, overflow_p
,
4427 /* Check that the LHS is constant and then discard it. */
4428 cxx_eval_constant_expression (ctx
, op0
,
4429 true, non_constant_p
, overflow_p
,
4431 if (*non_constant_p
)
4433 op1
= TREE_OPERAND (t
, 1);
4434 r
= cxx_eval_constant_expression (ctx
, op1
,
4435 lval
, non_constant_p
, overflow_p
,
4441 case POINTER_PLUS_EXPR
:
4442 case POINTER_DIFF_EXPR
:
4446 case TRUNC_DIV_EXPR
:
4448 case FLOOR_DIV_EXPR
:
4449 case ROUND_DIV_EXPR
:
4450 case TRUNC_MOD_EXPR
:
4452 case ROUND_MOD_EXPR
:
4454 case EXACT_DIV_EXPR
:
4464 case TRUTH_XOR_EXPR
:
4471 case UNORDERED_EXPR
:
4481 r
= cxx_eval_binary_expression (ctx
, t
, lval
,
4482 non_constant_p
, overflow_p
);
4485 /* fold can introduce non-IF versions of these; still treat them as
4486 short-circuiting. */
4487 case TRUTH_AND_EXPR
:
4488 case TRUTH_ANDIF_EXPR
:
4489 r
= cxx_eval_logical_expression (ctx
, t
, boolean_false_node
,
4492 non_constant_p
, overflow_p
);
4496 case TRUTH_ORIF_EXPR
:
4497 r
= cxx_eval_logical_expression (ctx
, t
, boolean_true_node
,
4500 non_constant_p
, overflow_p
);
4504 r
= cxx_eval_array_reference (ctx
, t
, lval
,
4505 non_constant_p
, overflow_p
);
4509 if (is_overloaded_fn (t
))
4511 /* We can only get here in checking mode via
4512 build_non_dependent_expr, because any expression that
4513 calls or takes the address of the function will have
4514 pulled a FUNCTION_DECL out of the COMPONENT_REF. */
4515 gcc_checking_assert (ctx
->quiet
|| errorcount
);
4516 *non_constant_p
= true;
4519 r
= cxx_eval_component_reference (ctx
, t
, lval
,
4520 non_constant_p
, overflow_p
);
4524 r
= cxx_eval_bit_field_ref (ctx
, t
, lval
,
4525 non_constant_p
, overflow_p
);
4529 if (jump_target
&& *jump_target
)
4531 /* When jumping to a label, the label might be either in the
4532 then or else blocks, so process then block first in skipping
4533 mode first, and if we are still in the skipping mode at its end,
4534 process the else block too. */
4535 r
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 1),
4536 lval
, non_constant_p
, overflow_p
,
4539 r
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 2),
4540 lval
, non_constant_p
, overflow_p
,
4544 r
= cxx_eval_conditional_expression (ctx
, t
, lval
,
4545 non_constant_p
, overflow_p
,
4549 r
= cxx_eval_vector_conditional_expression (ctx
, t
, non_constant_p
,
4554 if (TREE_CONSTANT (t
))
4556 /* Don't re-process a constant CONSTRUCTOR, but do fold it to
4557 VECTOR_CST if applicable. */
4558 verify_constructor_flags (t
);
4559 if (TREE_CONSTANT (t
))
4562 r
= cxx_eval_bare_aggregate (ctx
, t
, lval
,
4563 non_constant_p
, overflow_p
);
4567 /* We can get this in a defaulted constructor for a class with a
4568 non-static data member of array type. Either the initializer will
4569 be NULL, meaning default-initialization, or it will be an lvalue
4570 or xvalue of the same type, meaning direct-initialization from the
4571 corresponding member. */
4572 r
= cxx_eval_vec_init (ctx
, t
, lval
,
4573 non_constant_p
, overflow_p
);
4578 r
= cxx_eval_trinary_expression (ctx
, t
, lval
,
4579 non_constant_p
, overflow_p
);
4583 if (REINTERPRET_CAST_P (t
))
4586 error_at (EXPR_LOC_OR_LOC (t
, input_location
),
4587 "a reinterpret_cast is not a constant expression");
4588 *non_constant_p
= true;
4593 case VIEW_CONVERT_EXPR
:
4594 case UNARY_PLUS_EXPR
:
4596 tree oldop
= TREE_OPERAND (t
, 0);
4598 tree op
= cxx_eval_constant_expression (ctx
, oldop
,
4600 non_constant_p
, overflow_p
);
4601 if (*non_constant_p
)
4603 tree type
= TREE_TYPE (t
);
4604 if (TREE_CODE (op
) == PTRMEM_CST
4605 && !TYPE_PTRMEM_P (type
))
4606 op
= cplus_expand_constant (op
);
4608 if (TREE_CODE (op
) == PTRMEM_CST
&& tcode
== NOP_EXPR
)
4610 if (!same_type_ignoring_top_level_qualifiers_p (type
, TREE_TYPE (op
))
4611 && !can_convert_qual (type
, op
))
4612 op
= cplus_expand_constant (op
);
4613 return cp_fold_convert (type
, op
);
4616 if (POINTER_TYPE_P (type
) && TREE_CODE (op
) == INTEGER_CST
)
4618 if (integer_zerop (op
))
4620 if (TREE_CODE (type
) == REFERENCE_TYPE
)
4623 error_at (EXPR_LOC_OR_LOC (t
, input_location
),
4624 "dereferencing a null pointer");
4625 *non_constant_p
= true;
4628 else if (TREE_CODE (TREE_TYPE (op
)) == POINTER_TYPE
)
4630 tree from
= TREE_TYPE (op
);
4632 if (!can_convert (type
, from
, tf_none
))
4635 error_at (EXPR_LOC_OR_LOC (t
, input_location
),
4636 "conversion of %qT null pointer to %qT "
4637 "is not a constant expression",
4639 *non_constant_p
= true;
4646 /* This detects for example:
4647 reinterpret_cast<void*>(sizeof 0)
4650 error_at (EXPR_LOC_OR_LOC (t
, input_location
),
4651 "%<reinterpret_cast<%T>(%E)%> is not "
4652 "a constant expression",
4654 *non_constant_p
= true;
4659 if (op
== oldop
&& tcode
!= UNARY_PLUS_EXPR
)
4660 /* We didn't fold at the top so we could check for ptr-int
4664 if (tcode
== UNARY_PLUS_EXPR
)
4665 r
= fold_convert (TREE_TYPE (t
), op
);
4667 r
= fold_build1 (tcode
, type
, op
);
4669 /* Conversion of an out-of-range value has implementation-defined
4670 behavior; the language considers it different from arithmetic
4671 overflow, which is undefined. */
4672 if (TREE_OVERFLOW_P (r
) && !TREE_OVERFLOW_P (op
))
4673 TREE_OVERFLOW (r
) = false;
4677 case EMPTY_CLASS_EXPR
:
4678 /* This is good enough for a function argument that might not get
4679 used, and they can't do anything with it, so just return it. */
4682 case STATEMENT_LIST
:
4684 new_ctx
.ctor
= new_ctx
.object
= NULL_TREE
;
4685 return cxx_eval_statement_list (&new_ctx
, t
,
4686 non_constant_p
, overflow_p
, jump_target
);
4689 return cxx_eval_constant_expression (ctx
, BIND_EXPR_BODY (t
),
4691 non_constant_p
, overflow_p
,
4694 case PREINCREMENT_EXPR
:
4695 case POSTINCREMENT_EXPR
:
4696 case PREDECREMENT_EXPR
:
4697 case POSTDECREMENT_EXPR
:
4698 return cxx_eval_increment_expression (ctx
, t
,
4699 lval
, non_constant_p
, overflow_p
);
4705 case VEC_DELETE_EXPR
:
4708 /* GCC internal stuff. */
4711 case NON_DEPENDENT_EXPR
:
4715 error_at (EXPR_LOC_OR_LOC (t
, input_location
),
4716 "expression %qE is not a constant expression", t
);
4717 *non_constant_p
= true;
4720 case PLACEHOLDER_EXPR
:
4721 /* Use of the value or address of the current object. */
4722 if (tree ctor
= lookup_placeholder (ctx
, lval
, TREE_TYPE (t
)))
4723 return cxx_eval_constant_expression (ctx
, ctor
, lval
,
4724 non_constant_p
, overflow_p
);
4725 /* A placeholder without a referent. We can get here when
4726 checking whether NSDMIs are noexcept, or in massage_init_elt;
4727 just say it's non-constant for now. */
4728 gcc_assert (ctx
->quiet
);
4729 *non_constant_p
= true;
4734 tree cond
= TREE_OPERAND (t
, 0);
4735 cond
= cxx_eval_constant_expression (ctx
, cond
, /*lval*/false,
4736 non_constant_p
, overflow_p
);
4737 VERIFY_CONSTANT (cond
);
4738 if (integer_nonzerop (cond
))
4744 *jump_target
= TREE_OPERAND (t
, 0);
4745 gcc_assert (breaks (jump_target
) || continues (jump_target
)
4746 /* Allow for jumping to a cdtor_label. */
4747 || returns (jump_target
));
4751 cxx_eval_loop_expr (ctx
, t
,
4752 non_constant_p
, overflow_p
, jump_target
);
4756 cxx_eval_switch_expr (ctx
, t
,
4757 non_constant_p
, overflow_p
, jump_target
);
4761 /* It's possible to get a requires-expression in a constant
4762 expression. For example:
4764 template<typename T> concept bool C() {
4765 return requires (T t) { t; };
4768 template<typename T> requires !C<T>() void f(T);
4770 Normalization leaves f with the associated constraint
4771 '!requires (T t) { ... }' which is not transformed into
4773 if (!processing_template_decl
)
4774 return evaluate_constraint_expression (t
, NULL_TREE
);
4776 *non_constant_p
= true;
4780 r
= cxx_eval_constant_expression (ctx
, TREE_OPERAND (t
, 0),
4782 non_constant_p
, overflow_p
,
4791 if (STATEMENT_CODE_P (TREE_CODE (t
)))
4793 /* This function doesn't know how to deal with pre-genericize
4794 statements; this can only happen with statement-expressions,
4795 so for now just fail. */
4797 error_at (EXPR_LOCATION (t
),
4798 "statement is not a constant expression");
4801 internal_error ("unexpected expression %qE of kind %s", t
,
4802 get_tree_code_name (TREE_CODE (t
)));
4803 *non_constant_p
= true;
4807 if (r
== error_mark_node
)
4808 *non_constant_p
= true;
4810 if (*non_constant_p
)
4817 cxx_eval_outermost_constant_expr (tree t
, bool allow_non_constant
,
4818 bool strict
= true, tree object
= NULL_TREE
)
4820 auto_timevar
time (TV_CONSTEXPR
);
4822 bool non_constant_p
= false;
4823 bool overflow_p
= false;
4824 hash_map
<tree
,tree
> map
;
4826 constexpr_ctx ctx
= { NULL
, &map
, NULL
, NULL
, NULL
, NULL
,
4827 allow_non_constant
, strict
};
4829 tree type
= initialized_type (t
);
4831 if (AGGREGATE_TYPE_P (type
) || VECTOR_TYPE_P (type
))
4833 /* In C++14 an NSDMI can participate in aggregate initialization,
4834 and can refer to the address of the object being initialized, so
4835 we need to pass in the relevant VAR_DECL if we want to do the
4836 evaluation in a single pass. The evaluation will dynamically
4837 update ctx.values for the VAR_DECL. We use the same strategy
4838 for C++11 constexpr constructors that refer to the object being
4840 ctx
.ctor
= build_constructor (type
, NULL
);
4841 CONSTRUCTOR_NO_IMPLICIT_ZERO (ctx
.ctor
) = true;
4844 if (TREE_CODE (t
) == TARGET_EXPR
)
4845 object
= TARGET_EXPR_SLOT (t
);
4846 else if (TREE_CODE (t
) == AGGR_INIT_EXPR
)
4847 object
= AGGR_INIT_EXPR_SLOT (t
);
4849 ctx
.object
= object
;
4851 gcc_assert (same_type_ignoring_top_level_qualifiers_p
4852 (type
, TREE_TYPE (object
)));
4853 if (object
&& DECL_P (object
))
4854 map
.put (object
, ctx
.ctor
);
4855 if (TREE_CODE (r
) == TARGET_EXPR
)
4856 /* Avoid creating another CONSTRUCTOR when we expand the
4858 r
= TARGET_EXPR_INITIAL (r
);
4861 r
= cxx_eval_constant_expression (&ctx
, r
,
4862 false, &non_constant_p
, &overflow_p
);
4864 verify_constant (r
, allow_non_constant
, &non_constant_p
, &overflow_p
);
4866 /* Mutable logic is a bit tricky: we want to allow initialization of
4867 constexpr variables with mutable members, but we can't copy those
4868 members to another constexpr variable. */
4869 if (TREE_CODE (r
) == CONSTRUCTOR
4870 && CONSTRUCTOR_MUTABLE_POISON (r
))
4872 if (!allow_non_constant
)
4873 error ("%qE is not a constant expression because it refers to "
4874 "mutable subobjects of %qT", t
, type
);
4875 non_constant_p
= true;
4878 if (TREE_CODE (r
) == CONSTRUCTOR
4879 && CONSTRUCTOR_NO_IMPLICIT_ZERO (r
))
4881 if (!allow_non_constant
)
4882 error ("%qE is not a constant expression because it refers to "
4883 "an incompletely initialized variable", t
);
4884 TREE_CONSTANT (r
) = false;
4885 non_constant_p
= true;
4888 /* Technically we should check this for all subexpressions, but that
4889 runs into problems with our internal representation of pointer
4890 subtraction and the 5.19 rules are still in flux. */
4891 if (CONVERT_EXPR_CODE_P (TREE_CODE (r
))
4892 && ARITHMETIC_TYPE_P (TREE_TYPE (r
))
4893 && TREE_CODE (TREE_OPERAND (r
, 0)) == ADDR_EXPR
)
4895 if (!allow_non_constant
)
4896 error ("conversion from pointer type %qT "
4897 "to arithmetic type %qT in a constant expression",
4898 TREE_TYPE (TREE_OPERAND (r
, 0)), TREE_TYPE (r
));
4899 non_constant_p
= true;
4902 if (!non_constant_p
&& overflow_p
)
4903 non_constant_p
= true;
4905 /* Unshare the result unless it's a CONSTRUCTOR in which case it's already
4907 bool should_unshare
= true;
4908 if (r
== t
|| TREE_CODE (r
) == CONSTRUCTOR
)
4909 should_unshare
= false;
4911 if (non_constant_p
&& !allow_non_constant
)
4912 return error_mark_node
;
4913 else if (non_constant_p
&& TREE_CONSTANT (r
))
4915 /* This isn't actually constant, so unset TREE_CONSTANT.
4916 Don't clear TREE_CONSTANT on ADDR_EXPR, as the middle-end requires
4917 it to be set if it is invariant address, even when it is not
4918 a valid C++ constant expression. Wrap it with a NOP_EXPR
4920 if (EXPR_P (r
) && TREE_CODE (r
) != ADDR_EXPR
)
4922 else if (TREE_CODE (r
) == CONSTRUCTOR
)
4923 r
= build1 (VIEW_CONVERT_EXPR
, TREE_TYPE (r
), r
);
4925 r
= build_nop (TREE_TYPE (r
), r
);
4926 TREE_CONSTANT (r
) = false;
4928 else if (non_constant_p
|| r
== t
)
4932 r
= unshare_expr (r
);
4934 if (TREE_CODE (r
) == CONSTRUCTOR
&& CLASS_TYPE_P (TREE_TYPE (r
)))
4936 if (TREE_CODE (t
) == TARGET_EXPR
4937 && TARGET_EXPR_INITIAL (t
) == r
)
4941 r
= get_target_expr (r
);
4942 TREE_CONSTANT (r
) = true;
4950 /* Returns true if T is a valid subexpression of a constant expression,
4951 even if it isn't itself a constant expression. */
4954 is_sub_constant_expr (tree t
)
4956 bool non_constant_p
= false;
4957 bool overflow_p
= false;
4958 hash_map
<tree
, tree
> map
;
4960 constexpr_ctx ctx
= { NULL
, &map
, NULL
, NULL
, NULL
, NULL
, true, true };
4962 cxx_eval_constant_expression (&ctx
, t
, false, &non_constant_p
,
4964 return !non_constant_p
&& !overflow_p
;
4967 /* If T represents a constant expression returns its reduced value.
4968 Otherwise return error_mark_node. If T is dependent, then
4972 cxx_constant_value (tree t
, tree decl
)
4974 return cxx_eval_outermost_constant_expr (t
, false, true, decl
);
4977 /* Helper routine for fold_simple function. Either return simplified
4978 expression T, otherwise NULL_TREE.
4979 In contrast to cp_fully_fold, and to maybe_constant_value, we try to fold
4980 even if we are within template-declaration. So be careful on call, as in
4981 such case types can be undefined. */
4984 fold_simple_1 (tree t
)
4987 enum tree_code code
= TREE_CODE (t
);
4999 return fold_sizeof_expr (t
);
5007 case TRUTH_NOT_EXPR
:
5009 case VIEW_CONVERT_EXPR
:
5012 case FIX_TRUNC_EXPR
:
5013 case FIXED_CONVERT_EXPR
:
5014 case ADDR_SPACE_CONVERT_EXPR
:
5016 op1
= TREE_OPERAND (t
, 0);
5018 t
= const_unop (code
, TREE_TYPE (t
), op1
);
5022 if (CONVERT_EXPR_CODE_P (code
)
5023 && TREE_OVERFLOW_P (t
) && !TREE_OVERFLOW_P (op1
))
5024 TREE_OVERFLOW (t
) = false;
5032 /* If T is a simple constant expression, returns its simplified value.
5033 Otherwise returns T. In contrast to maybe_constant_value we
5034 simplify only few operations on constant-expressions, and we don't
5035 try to simplify constexpressions. */
5038 fold_simple (tree t
)
5040 if (processing_template_decl
)
5043 tree r
= fold_simple_1 (t
);
5050 /* If T is a constant expression, returns its reduced value.
5051 Otherwise, if T does not have TREE_CONSTANT set, returns T.
5052 Otherwise, returns a version of T without TREE_CONSTANT. */
5054 static GTY((deletable
)) hash_map
<tree
, tree
> *cv_cache
;
5057 maybe_constant_value (tree t
, tree decl
)
5061 if (!is_nondependent_constant_expression (t
))
5063 if (TREE_OVERFLOW_P (t
))
5065 t
= build_nop (TREE_TYPE (t
), t
);
5066 TREE_CONSTANT (t
) = false;
5070 else if (CONSTANT_CLASS_P (t
))
5071 /* No caching or evaluation needed. */
5074 if (cv_cache
== NULL
)
5075 cv_cache
= hash_map
<tree
, tree
>::create_ggc (101);
5076 if (tree
*cached
= cv_cache
->get (t
))
5079 r
= cxx_eval_outermost_constant_expr (t
, true, true, decl
);
5080 gcc_checking_assert (r
== t
5081 || CONVERT_EXPR_P (t
)
5082 || TREE_CODE (t
) == VIEW_CONVERT_EXPR
5083 || (TREE_CONSTANT (t
) && !TREE_CONSTANT (r
))
5084 || !cp_tree_equal (r
, t
));
5085 cv_cache
->put (t
, r
);
5089 /* Dispose of the whole CV_CACHE. */
5092 clear_cv_cache (void)
5094 if (cv_cache
!= NULL
)
5098 /* Dispose of the whole CV_CACHE and FOLD_CACHE. */
5101 clear_cv_and_fold_caches (void)
5104 clear_fold_cache ();
5107 /* Like maybe_constant_value but first fully instantiate the argument.
5109 Note: this is equivalent to instantiate_non_dependent_expr_sfinae
5110 (t, tf_none) followed by maybe_constant_value but is more efficient,
5111 because calls instantiation_dependent_expression_p and
5112 potential_constant_expression at most once. */
5115 fold_non_dependent_expr (tree t
)
5120 /* If we're in a template, but T isn't value dependent, simplify
5121 it. We're supposed to treat:
5123 template <typename T> void f(T[1 + 1]);
5124 template <typename T> void f(T[2]);
5126 as two declarations of the same function, for example. */
5127 if (processing_template_decl
)
5129 if (is_nondependent_constant_expression (t
))
5131 processing_template_decl_sentinel s
;
5132 t
= instantiate_non_dependent_expr_internal (t
, tf_none
);
5134 if (type_unknown_p (t
)
5135 || BRACE_ENCLOSED_INITIALIZER_P (t
))
5137 if (TREE_OVERFLOW_P (t
))
5139 t
= build_nop (TREE_TYPE (t
), t
);
5140 TREE_CONSTANT (t
) = false;
5145 tree r
= cxx_eval_outermost_constant_expr (t
, true, true, NULL_TREE
);
5146 /* cp_tree_equal looks through NOPs, so allow them. */
5147 gcc_checking_assert (r
== t
5148 || CONVERT_EXPR_P (t
)
5149 || TREE_CODE (t
) == VIEW_CONVERT_EXPR
5150 || (TREE_CONSTANT (t
) && !TREE_CONSTANT (r
))
5151 || !cp_tree_equal (r
, t
));
5154 else if (TREE_OVERFLOW_P (t
))
5156 t
= build_nop (TREE_TYPE (t
), t
);
5157 TREE_CONSTANT (t
) = false;
5162 return maybe_constant_value (t
);
5165 /* Like maybe_constant_value, but returns a CONSTRUCTOR directly, rather
5166 than wrapped in a TARGET_EXPR. */
5169 maybe_constant_init_1 (tree t
, tree decl
, bool allow_non_constant
)
5173 if (TREE_CODE (t
) == EXPR_STMT
)
5174 t
= TREE_OPERAND (t
, 0);
5175 if (TREE_CODE (t
) == CONVERT_EXPR
5176 && VOID_TYPE_P (TREE_TYPE (t
)))
5177 t
= TREE_OPERAND (t
, 0);
5178 if (TREE_CODE (t
) == INIT_EXPR
)
5179 t
= TREE_OPERAND (t
, 1);
5180 if (TREE_CODE (t
) == TARGET_EXPR
)
5181 t
= TARGET_EXPR_INITIAL (t
);
5182 if (!is_nondependent_static_init_expression (t
))
5183 /* Don't try to evaluate it. */;
5184 else if (CONSTANT_CLASS_P (t
) && allow_non_constant
)
5185 /* No evaluation needed. */;
5187 t
= cxx_eval_outermost_constant_expr (t
, allow_non_constant
, false, decl
);
5188 if (TREE_CODE (t
) == TARGET_EXPR
)
5190 tree init
= TARGET_EXPR_INITIAL (t
);
5191 if (TREE_CODE (init
) == CONSTRUCTOR
)
5197 /* Wrapper for maybe_constant_init_1 which permits non constants. */
5200 maybe_constant_init (tree t
, tree decl
)
5202 return maybe_constant_init_1 (t
, decl
, true);
5205 /* Wrapper for maybe_constant_init_1 which does not permit non constants. */
5208 cxx_constant_init (tree t
, tree decl
)
5210 return maybe_constant_init_1 (t
, decl
, false);
5214 /* FIXME see ADDR_EXPR section in potential_constant_expression_1. */
5215 /* Return true if the object referred to by REF has automatic or thread
5218 enum { ck_ok
, ck_bad
, ck_unknown
};
5220 check_automatic_or_tls (tree ref
)
5223 poly_int64 bitsize
, bitpos
;
5225 int volatilep
= 0, unsignedp
= 0;
5226 tree decl
= get_inner_reference (ref
, &bitsize
, &bitpos
, &offset
,
5227 &mode
, &unsignedp
, &volatilep
, false);
5230 /* If there isn't a decl in the middle, we don't know the linkage here,
5231 and this isn't a constant expression anyway. */
5234 dk
= decl_storage_duration (decl
);
5235 return (dk
== dk_auto
|| dk
== dk_thread
) ? ck_bad
: ck_ok
;
5239 /* Return true if T denotes a potentially constant expression. Issue
5240 diagnostic as appropriate under control of FLAGS. If WANT_RVAL is true,
5241 an lvalue-rvalue conversion is implied. If NOW is true, we want to
5242 consider the expression in the current context, independent of constexpr
5245 C++0x [expr.const] used to say
5247 6 An expression is a potential constant expression if it is
5248 a constant expression where all occurrences of function
5249 parameters are replaced by arbitrary constant expressions
5250 of the appropriate type.
5252 2 A conditional expression is a constant expression unless it
5253 involves one of the following as a potentially evaluated
5254 subexpression (3.2), but subexpressions of logical AND (5.14),
5255 logical OR (5.15), and conditional (5.16) operations that are
5256 not evaluated are not considered. */
5259 potential_constant_expression_1 (tree t
, bool want_rval
, bool strict
, bool now
,
5260 tsubst_flags_t flags
)
5262 #define RECUR(T,RV) \
5263 potential_constant_expression_1 ((T), (RV), strict, now, flags)
5265 enum { any
= false, rval
= true };
5269 if (t
== error_mark_node
)
5273 location_t loc
= EXPR_LOC_OR_LOC (t
, input_location
);
5274 if (TREE_THIS_VOLATILE (t
) && !DECL_P (t
))
5276 if (flags
& tf_error
)
5277 error_at (loc
, "expression %qE has side-effects", t
);
5280 if (CONSTANT_CLASS_P (t
))
5282 if (CODE_CONTAINS_STRUCT (TREE_CODE (t
), TS_TYPED
)
5283 && TREE_TYPE (t
) == error_mark_node
)
5286 switch (TREE_CODE (t
))
5292 case TEMPLATE_ID_EXPR
:
5295 case CASE_LABEL_EXPR
:
5301 case TEMPLATE_PARM_INDEX
:
5303 case IDENTIFIER_NODE
:
5304 case USERDEF_LITERAL
:
5305 /* We can see a FIELD_DECL in a pointer-to-member expression. */
5310 case PLACEHOLDER_EXPR
:
5315 case DEBUG_BEGIN_STMT
:
5321 if (flags
& tf_error
)
5322 error ("%qE is not a constant expression", t
);
5327 case AGGR_INIT_EXPR
:
5329 /* -- an invocation of a function other than a constexpr function
5330 or a constexpr constructor. */
5332 tree fun
= get_function_named_in_call (t
);
5333 const int nargs
= call_expr_nargs (t
);
5336 if (fun
== NULL_TREE
)
5338 /* Reset to allow the function to continue past the end
5339 of the block below. Otherwise return early. */
5342 if (TREE_CODE (t
) == CALL_EXPR
5343 && CALL_EXPR_FN (t
) == NULL_TREE
)
5344 switch (CALL_EXPR_IFN (t
))
5346 /* These should be ignored, they are optimized away from
5347 constexpr functions. */
5348 case IFN_UBSAN_NULL
:
5349 case IFN_UBSAN_BOUNDS
:
5350 case IFN_UBSAN_VPTR
:
5351 case IFN_FALLTHROUGH
:
5354 case IFN_ADD_OVERFLOW
:
5355 case IFN_SUB_OVERFLOW
:
5356 case IFN_MUL_OVERFLOW
:
5366 /* fold_call_expr can't do anything with IFN calls. */
5367 if (flags
& tf_error
)
5368 error_at (loc
, "call to internal function %qE", t
);
5373 if (fun
&& is_overloaded_fn (fun
))
5375 if (TREE_CODE (fun
) == FUNCTION_DECL
)
5377 if (builtin_valid_in_constant_expr_p (fun
))
5379 if (!DECL_DECLARED_CONSTEXPR_P (fun
)
5380 /* Allow any built-in function; if the expansion
5381 isn't constant, we'll deal with that then. */
5382 && !is_builtin_fn (fun
))
5384 if (flags
& tf_error
)
5386 error_at (loc
, "call to non-%<constexpr%> function %qD",
5388 explain_invalid_constexpr_fn (fun
);
5392 /* A call to a non-static member function takes the address
5393 of the object as the first argument. But in a constant
5394 expression the address will be folded away, so look
5396 if (DECL_NONSTATIC_MEMBER_FUNCTION_P (fun
)
5397 && !DECL_CONSTRUCTOR_P (fun
))
5399 tree x
= get_nth_callarg (t
, 0);
5400 if (is_this_parameter (x
))
5402 /* Don't require an immediately constant value, as
5403 constexpr substitution might not use the value. */
5404 bool sub_now
= false;
5405 if (!potential_constant_expression_1 (x
, rval
, strict
,
5413 if (!RECUR (fun
, true))
5415 fun
= get_first_fn (fun
);
5417 /* Skip initial arguments to base constructors. */
5418 if (DECL_BASE_CONSTRUCTOR_P (fun
))
5419 i
= num_artificial_parms_for (fun
);
5420 fun
= DECL_ORIGIN (fun
);
5424 if (RECUR (fun
, rval
))
5425 /* Might end up being a constant function pointer. */;
5429 for (; i
< nargs
; ++i
)
5431 tree x
= get_nth_callarg (t
, i
);
5432 /* In a template, reference arguments haven't been converted to
5433 REFERENCE_TYPE and we might not even know if the parameter
5434 is a reference, so accept lvalue constants too. */
5435 bool rv
= processing_template_decl
? any
: rval
;
5436 /* Don't require an immediately constant value, as constexpr
5437 substitution might not use the value of the argument. */
5438 bool sub_now
= false;
5439 if (!potential_constant_expression_1 (x
, rv
, strict
,
5446 case NON_LVALUE_EXPR
:
5447 /* -- an lvalue-to-rvalue conversion (4.1) unless it is applied to
5448 -- an lvalue of integral type that refers to a non-volatile
5449 const variable or static data member initialized with
5450 constant expressions, or
5452 -- an lvalue of literal type that refers to non-volatile
5453 object defined with constexpr, or that refers to a
5454 sub-object of such an object; */
5455 return RECUR (TREE_OPERAND (t
, 0), rval
);
5458 if (DECL_HAS_VALUE_EXPR_P (t
))
5460 if (now
&& is_normal_capture_proxy (t
))
5462 /* -- in a lambda-expression, a reference to this or to a
5463 variable with automatic storage duration defined outside that
5464 lambda-expression, where the reference would be an
5466 if (flags
& tf_error
)
5468 tree cap
= DECL_CAPTURED_VARIABLE (t
);
5469 error ("lambda capture of %qE is not a constant expression",
5471 if (!want_rval
&& decl_constant_var_p (cap
))
5472 inform (input_location
, "because it is used as a glvalue");
5476 return RECUR (DECL_VALUE_EXPR (t
), rval
);
5479 && !var_in_maybe_constexpr_fn (t
)
5480 && !type_dependent_expression_p (t
)
5481 && !decl_maybe_constant_var_p (t
)
5483 || !CP_TYPE_CONST_NON_VOLATILE_P (TREE_TYPE (t
))
5484 || (DECL_INITIAL (t
)
5485 && !DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (t
)))
5486 && COMPLETE_TYPE_P (TREE_TYPE (t
))
5487 && !is_really_empty_class (TREE_TYPE (t
)))
5489 if (flags
& tf_error
)
5490 non_const_var_error (t
);
5497 case VIEW_CONVERT_EXPR
:
5498 /* -- a reinterpret_cast. FIXME not implemented, and this rule
5499 may change to something more specific to type-punning (DR 1312). */
5501 tree from
= TREE_OPERAND (t
, 0);
5502 if (POINTER_TYPE_P (TREE_TYPE (t
))
5503 && TREE_CODE (from
) == INTEGER_CST
5504 && !integer_zerop (from
))
5506 if (flags
& tf_error
)
5507 error_at (loc
, "reinterpret_cast from integer to pointer");
5510 return (RECUR (from
, TREE_CODE (t
) != VIEW_CONVERT_EXPR
));
5513 case ADDRESSOF_EXPR
:
5514 /* This is like ADDR_EXPR, except it won't form pointer-to-member. */
5515 t
= TREE_OPERAND (t
, 0);
5516 goto handle_addr_expr
;
5519 /* -- a unary operator & that is applied to an lvalue that
5520 designates an object with thread or automatic storage
5522 t
= TREE_OPERAND (t
, 0);
5524 if (TREE_CODE (t
) == OFFSET_REF
&& PTRMEM_OK_P (t
))
5525 /* A pointer-to-member constant. */
5530 /* FIXME adjust when issue 1197 is fully resolved. For now don't do
5531 any checking here, as we might dereference the pointer later. If
5532 we remove this code, also remove check_automatic_or_tls. */
5533 i
= check_automatic_or_tls (t
);
5538 if (flags
& tf_error
)
5539 error ("address-of an object %qE with thread local or "
5540 "automatic storage is not a constant expression", t
);
5544 return RECUR (t
, any
);
5552 /* -- a class member access unless its postfix-expression is
5553 of literal type or of pointer to literal type. */
5554 /* This test would be redundant, as it follows from the
5555 postfix-expression being a potential constant expression. */
5556 if (type_unknown_p (t
))
5558 return RECUR (TREE_OPERAND (t
, 0), want_rval
);
5560 case EXPR_PACK_EXPANSION
:
5561 return RECUR (PACK_EXPANSION_PATTERN (t
), want_rval
);
5565 tree x
= TREE_OPERAND (t
, 0);
5567 if (is_this_parameter (x
) && !is_capture_proxy (x
))
5569 if (!var_in_maybe_constexpr_fn (x
))
5571 if (flags
& tf_error
)
5572 error_at (loc
, "use of %<this%> in a constant expression");
5577 return RECUR (x
, rval
);
5580 case STATEMENT_LIST
:
5582 tree_stmt_iterator i
;
5583 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
5585 if (!RECUR (tsi_stmt (i
), any
))
5593 if (cxx_dialect
< cxx14
)
5595 if (!RECUR (TREE_OPERAND (t
, 0), any
))
5597 if (!RECUR (TREE_OPERAND (t
, 1), rval
))
5602 if (cxx_dialect
< cxx14
)
5604 if (!RECUR (TREE_OPERAND (t
, 0), rval
))
5606 if (!RECUR (TREE_OPERAND (t
, 2), rval
))
5611 if (!RECUR (DO_COND (t
), rval
))
5613 if (!RECUR (DO_BODY (t
), any
))
5618 if (!RECUR (FOR_INIT_STMT (t
), any
))
5620 if (!RECUR (FOR_COND (t
), rval
))
5622 if (!RECUR (FOR_EXPR (t
), any
))
5624 if (!RECUR (FOR_BODY (t
), any
))
5628 case RANGE_FOR_STMT
:
5629 if (!RECUR (RANGE_FOR_EXPR (t
), any
))
5631 if (!RECUR (RANGE_FOR_BODY (t
), any
))
5636 if (!RECUR (WHILE_COND (t
), rval
))
5638 if (!RECUR (WHILE_BODY (t
), any
))
5643 if (!RECUR (SWITCH_STMT_COND (t
), rval
))
5645 /* FIXME we don't check SWITCH_STMT_BODY currently, because even
5646 unreachable labels would be checked. */
5650 return RECUR (STMT_EXPR_STMT (t
), rval
);
5653 if (cxx_dialect
>= cxx17
)
5654 /* In C++17 lambdas can be constexpr, don't give up yet. */
5656 else if (flags
& tf_error
)
5657 error_at (loc
, "lambda-expression is not a constant expression "
5661 case DYNAMIC_CAST_EXPR
:
5662 case PSEUDO_DTOR_EXPR
:
5666 case VEC_DELETE_EXPR
:
5672 case OMP_DISTRIBUTE
:
5675 case OMP_TARGET_DATA
:
5684 case OMP_TARGET_UPDATE
:
5685 case OMP_TARGET_ENTER_DATA
:
5686 case OMP_TARGET_EXIT_DATA
:
5688 case OMP_ATOMIC_READ
:
5689 case OMP_ATOMIC_CAPTURE_OLD
:
5690 case OMP_ATOMIC_CAPTURE_NEW
:
5694 case OACC_HOST_DATA
:
5698 case OACC_ENTER_DATA
:
5699 case OACC_EXIT_DATA
:
5701 /* GCC internal stuff. */
5704 case TRANSACTION_EXPR
:
5706 case AT_ENCODE_EXPR
:
5708 if (flags
& tf_error
)
5709 error_at (loc
, "expression %qE is not a constant expression", t
);
5713 /* -- a typeid expression whose operand is of polymorphic
5716 tree e
= TREE_OPERAND (t
, 0);
5717 if (!TYPE_P (e
) && !type_dependent_expression_p (e
)
5718 && TYPE_POLYMORPHIC_P (TREE_TYPE (e
)))
5720 if (flags
& tf_error
)
5721 error_at (loc
, "typeid-expression is not a constant expression "
5722 "because %qE is of polymorphic type", e
);
5728 case POINTER_DIFF_EXPR
:
5742 case PREINCREMENT_EXPR
:
5743 case POSTINCREMENT_EXPR
:
5744 case PREDECREMENT_EXPR
:
5745 case POSTDECREMENT_EXPR
:
5746 if (cxx_dialect
< cxx14
)
5752 if (TYPE_P (TREE_OPERAND (t
, 0)))
5758 case FIX_TRUNC_EXPR
:
5762 case TRUTH_NOT_EXPR
:
5763 case FIXED_CONVERT_EXPR
:
5764 case UNARY_PLUS_EXPR
:
5765 case UNARY_LEFT_FOLD_EXPR
:
5766 case UNARY_RIGHT_FOLD_EXPR
:
5768 return RECUR (TREE_OPERAND (t
, 0), rval
);
5771 case CONST_CAST_EXPR
:
5772 case STATIC_CAST_EXPR
:
5773 case REINTERPRET_CAST_EXPR
:
5774 case IMPLICIT_CONV_EXPR
:
5775 if (cxx_dialect
< cxx11
5776 && !dependent_type_p (TREE_TYPE (t
))
5777 && !INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (t
)))
5778 /* In C++98, a conversion to non-integral type can't be part of a
5779 constant expression. */
5781 if (flags
& tf_error
)
5783 "cast to non-integral type %qT in a constant expression",
5787 /* This might be a conversion from a class to a (potentially) literal
5788 type. Let's consider it potentially constant since the conversion
5789 might be a constexpr user-defined conversion. */
5790 else if (cxx_dialect
>= cxx11
5791 && (dependent_type_p (TREE_TYPE (t
))
5792 || !COMPLETE_TYPE_P (TREE_TYPE (t
))
5793 || literal_type_p (TREE_TYPE (t
)))
5794 && TREE_OPERAND (t
, 0))
5796 tree type
= TREE_TYPE (TREE_OPERAND (t
, 0));
5797 /* If this is a dependent type, it could end up being a class
5798 with conversions. */
5799 if (type
== NULL_TREE
|| WILDCARD_TYPE_P (type
))
5801 /* Or a non-dependent class which has conversions. */
5802 else if (CLASS_TYPE_P (type
)
5803 && (TYPE_HAS_CONVERSION (type
) || dependent_scope_p (type
)))
5807 return (RECUR (TREE_OPERAND (t
, 0),
5808 TREE_CODE (TREE_TYPE (t
)) != REFERENCE_TYPE
));
5811 return RECUR (BIND_EXPR_BODY (t
), want_rval
);
5813 case CLEANUP_POINT_EXPR
:
5814 case MUST_NOT_THROW_EXPR
:
5815 case TRY_CATCH_EXPR
:
5820 case NON_DEPENDENT_EXPR
:
5821 /* For convenience. */
5825 return RECUR (TREE_OPERAND (t
, 0), want_rval
);
5828 tmp
= DECL_EXPR_DECL (t
);
5829 if (VAR_P (tmp
) && !DECL_ARTIFICIAL (tmp
))
5831 if (TREE_STATIC (tmp
))
5833 if (flags
& tf_error
)
5834 error_at (DECL_SOURCE_LOCATION (tmp
), "%qD declared "
5835 "%<static%> in %<constexpr%> context", tmp
);
5838 else if (CP_DECL_THREAD_LOCAL_P (tmp
))
5840 if (flags
& tf_error
)
5841 error_at (DECL_SOURCE_LOCATION (tmp
), "%qD declared "
5842 "%<thread_local%> in %<constexpr%> context", tmp
);
5845 else if (!check_for_uninitialized_const_var
5846 (tmp
, /*constexpr_context_p=*/true, flags
))
5849 return RECUR (tmp
, want_rval
);
5851 case TRY_FINALLY_EXPR
:
5852 return (RECUR (TREE_OPERAND (t
, 0), want_rval
)
5853 && RECUR (TREE_OPERAND (t
, 1), any
));
5856 return RECUR (TREE_OPERAND (t
, 1), want_rval
);
5859 if (!TARGET_EXPR_DIRECT_INIT_P (t
)
5860 && !literal_type_p (TREE_TYPE (t
)))
5862 if (flags
& tf_error
)
5864 error_at (loc
, "temporary of non-literal type %qT in a "
5865 "constant expression", TREE_TYPE (t
));
5866 explain_non_literal_class (TREE_TYPE (t
));
5872 return RECUR (TREE_OPERAND (t
, 1), rval
);
5876 vec
<constructor_elt
, va_gc
> *v
= CONSTRUCTOR_ELTS (t
);
5877 constructor_elt
*ce
;
5878 for (i
= 0; vec_safe_iterate (v
, i
, &ce
); ++i
)
5879 if (!RECUR (ce
->value
, want_rval
))
5886 gcc_assert (TREE_PURPOSE (t
) == NULL_TREE
5887 || DECL_P (TREE_PURPOSE (t
)));
5888 if (!RECUR (TREE_VALUE (t
), want_rval
))
5890 if (TREE_CHAIN (t
) == NULL_TREE
)
5892 return RECUR (TREE_CHAIN (t
), want_rval
);
5895 case TRUNC_DIV_EXPR
:
5897 case FLOOR_DIV_EXPR
:
5898 case ROUND_DIV_EXPR
:
5899 case TRUNC_MOD_EXPR
:
5901 case ROUND_MOD_EXPR
:
5903 tree denom
= TREE_OPERAND (t
, 1);
5904 if (!RECUR (denom
, rval
))
5906 /* We can't call cxx_eval_outermost_constant_expr on an expression
5907 that hasn't been through instantiate_non_dependent_expr yet. */
5908 if (!processing_template_decl
)
5909 denom
= cxx_eval_outermost_constant_expr (denom
, true);
5910 if (integer_zerop (denom
))
5912 if (flags
& tf_error
)
5913 error ("division by zero is not a constant expression");
5919 return RECUR (TREE_OPERAND (t
, 0), want_rval
);
5925 /* check_return_expr sometimes wraps a TARGET_EXPR in a
5926 COMPOUND_EXPR; don't get confused. Also handle EMPTY_CLASS_EXPR
5927 introduced by build_call_a. */
5928 tree op0
= TREE_OPERAND (t
, 0);
5929 tree op1
= TREE_OPERAND (t
, 1);
5931 if ((TREE_CODE (op0
) == TARGET_EXPR
&& op1
== TARGET_EXPR_SLOT (op0
))
5932 || TREE_CODE (op1
) == EMPTY_CLASS_EXPR
)
5933 return RECUR (op0
, want_rval
);
5938 /* If the first operand is the non-short-circuit constant, look at
5939 the second operand; otherwise we only care about the first one for
5941 case TRUTH_AND_EXPR
:
5942 case TRUTH_ANDIF_EXPR
:
5943 tmp
= boolean_true_node
;
5946 case TRUTH_ORIF_EXPR
:
5947 tmp
= boolean_false_node
;
5950 tree op
= TREE_OPERAND (t
, 0);
5951 if (!RECUR (op
, rval
))
5953 if (!processing_template_decl
)
5954 op
= cxx_eval_outermost_constant_expr (op
, true);
5955 if (tree_int_cst_equal (op
, tmp
))
5956 return RECUR (TREE_OPERAND (t
, 1), rval
);
5963 case POINTER_PLUS_EXPR
:
5965 case EXACT_DIV_EXPR
:
5975 case TRUTH_XOR_EXPR
:
5976 case UNORDERED_EXPR
:
5989 case ARRAY_RANGE_REF
:
5993 case BINARY_LEFT_FOLD_EXPR
:
5994 case BINARY_RIGHT_FOLD_EXPR
:
5996 for (i
= 0; i
< 2; ++i
)
5997 if (!RECUR (TREE_OPERAND (t
, i
), want_rval
))
6003 for (i
= 0; i
< 3; ++i
)
6004 if (!RECUR (TREE_OPERAND (t
, i
), true))
6009 if (COND_EXPR_IS_VEC_DELETE (t
))
6011 if (flags
& tf_error
)
6012 error_at (loc
, "%<delete[]%> is not a constant expression");
6018 /* If the condition is a known constant, we know which of the legs we
6019 care about; otherwise we only require that the condition and
6020 either of the legs be potentially constant. */
6021 tmp
= TREE_OPERAND (t
, 0);
6022 if (!RECUR (tmp
, rval
))
6024 if (!processing_template_decl
)
6025 tmp
= cxx_eval_outermost_constant_expr (tmp
, true);
6026 if (integer_zerop (tmp
))
6027 return RECUR (TREE_OPERAND (t
, 2), want_rval
);
6028 else if (TREE_CODE (tmp
) == INTEGER_CST
)
6029 return RECUR (TREE_OPERAND (t
, 1), want_rval
);
6030 for (i
= 1; i
< 3; ++i
)
6031 if (potential_constant_expression_1 (TREE_OPERAND (t
, i
),
6032 want_rval
, strict
, now
, tf_none
))
6034 if (flags
& tf_error
)
6035 error_at (loc
, "expression %qE is not a constant expression", t
);
6039 if (VEC_INIT_EXPR_IS_CONSTEXPR (t
))
6041 if (flags
& tf_error
)
6043 error_at (loc
, "non-constant array initialization");
6044 diagnose_non_constexpr_vec_init (t
);
6050 /* We can see these in statement-expressions. */
6054 case EMPTY_CLASS_EXPR
:
6060 tree
*target
= &TREE_OPERAND (t
, 0);
6061 /* Gotos representing break and continue are OK. */
6062 if (breaks (target
) || continues (target
))
6064 if (flags
& tf_error
)
6065 error_at (loc
, "%<goto%> is not a constant expression");
6070 return RECUR (TREE_OPERAND (t
, 0), rval
);
6073 if (objc_is_property_ref (t
))
6076 sorry ("unexpected AST of kind %s", get_tree_code_name (TREE_CODE (t
)));
6083 /* The main entry point to the above. */
6086 potential_constant_expression (tree t
)
6088 return potential_constant_expression_1 (t
, false, true, false, tf_none
);
6091 /* As above, but require a constant rvalue. */
6094 potential_rvalue_constant_expression (tree t
)
6096 return potential_constant_expression_1 (t
, true, true, false, tf_none
);
6099 /* Like above, but complain about non-constant expressions. */
6102 require_potential_constant_expression (tree t
)
6104 return potential_constant_expression_1 (t
, false, true, false,
6105 tf_warning_or_error
);
6108 /* Cross product of the above. */
6111 require_potential_rvalue_constant_expression (tree t
)
6113 return potential_constant_expression_1 (t
, true, true, false,
6114 tf_warning_or_error
);
6117 /* Like above, but don't consider PARM_DECL a potential_constant_expression. */
6120 require_rvalue_constant_expression (tree t
)
6122 return potential_constant_expression_1 (t
, true, true, true,
6123 tf_warning_or_error
);
6126 /* Like potential_constant_expression, but don't consider possible constexpr
6127 substitution of the current function. That is, PARM_DECL qualifies under
6128 potential_constant_expression, but not here.
6130 This is basically what you can check when any actual constant values might
6131 be value-dependent. */
6134 is_constant_expression (tree t
)
6136 return potential_constant_expression_1 (t
, false, true, true, tf_none
);
6139 /* Like above, but complain about non-constant expressions. */
6142 require_constant_expression (tree t
)
6144 return potential_constant_expression_1 (t
, false, true, true,
6145 tf_warning_or_error
);
6148 /* Like is_constant_expression, but allow const variables that are not allowed
6149 under constexpr rules. */
6152 is_static_init_expression (tree t
)
6154 return potential_constant_expression_1 (t
, false, false, true, tf_none
);
6157 /* Returns true if T is a potential constant expression that is not
6158 instantiation-dependent, and therefore a candidate for constant folding even
6162 is_nondependent_constant_expression (tree t
)
6164 return (!type_unknown_p (t
)
6165 && !BRACE_ENCLOSED_INITIALIZER_P (t
)
6166 && is_constant_expression (t
)
6167 && !instantiation_dependent_expression_p (t
));
6170 /* Returns true if T is a potential static initializer expression that is not
6171 instantiation-dependent. */
6174 is_nondependent_static_init_expression (tree t
)
6176 return (!type_unknown_p (t
)
6177 && !BRACE_ENCLOSED_INITIALIZER_P (t
)
6178 && is_static_init_expression (t
)
6179 && !instantiation_dependent_expression_p (t
));
6182 /* Finalize constexpr processing after parsing. */
6185 fini_constexpr (void)
6187 /* The contexpr call and fundef copies tables are no longer needed. */
6188 constexpr_call_table
= NULL
;
6189 fundef_copies_table
= NULL
;
6192 #include "gt-cp-constexpr.h"