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 if (TREE_CODE (temp) == EMPTY_CLASS_EXPR)
1256 return build0 (EMPTY_CLASS_EXPR, type);
1257 gcc_assert (scalarish_type_p (type));
1258 return cp_fold_convert (type, temp);
1261 /* Callback for walk_tree used by unshare_constructor. */
1264 find_constructor (tree *tp, int *walk_subtrees, void *)
1268 if (TREE_CODE (*tp) == CONSTRUCTOR)
1273 /* If T is a CONSTRUCTOR or an expression that has a CONSTRUCTOR node as a
1274 subexpression, return an unshared copy of T. Otherwise return T. */
1277 unshare_constructor (tree t)
1279 tree ctor = walk_tree (&t, find_constructor, NULL, NULL);
1280 if (ctor != NULL_TREE)
1281 return unshare_expr (t);
1285 /* Subroutine of cxx_eval_call_expression.
1286 We are processing a call expression (either CALL_EXPR or
1287 AGGR_INIT_EXPR) in the context of CTX. Evaluate
1288 all arguments and bind their values to correspondings
1289 parameters, making up the NEW_CALL context. */
1292 cxx_bind_parameters_in_call (const constexpr_ctx *ctx, tree t,
1293 constexpr_call *new_call,
1294 bool *non_constant_p, bool *overflow_p,
1295 bool *non_constant_args)
1297 const int nargs = call_expr_nargs (t);
1298 tree fun = new_call->fundef->decl;
1299 tree parms = DECL_ARGUMENTS (fun);
1301 tree *p = &new_call->bindings;
1302 for (i = 0; i < nargs; ++i)
1305 tree type = parms ? TREE_TYPE (parms) : void_type_node;
1306 x = get_nth_callarg (t, i);
1307 /* For member function, the first argument is a pointer to the implied
1308 object. For a constructor, it might still be a dummy object, in
1309 which case we get the real argument from ctx. */
1310 if (i == 0 && DECL_CONSTRUCTOR_P (fun)
1311 && is_dummy_object (x))
1314 x = build_address (x);
1316 arg = cxx_eval_constant_expression (ctx, x, /*lval=*/false,
1317 non_constant_p, overflow_p);
1318 /* Don't VERIFY_CONSTANT here. */
1319 if (*non_constant_p && ctx->quiet)
1321 /* Just discard ellipsis args after checking their constantitude. */
1325 if (!*non_constant_p)
1327 /* Don't share a CONSTRUCTOR that might be changed. */
1328 arg = unshare_constructor (arg);
1329 /* Make sure the binding has the same type as the parm. But
1330 only for constant args. */
1331 if (TREE_CODE (type) != REFERENCE_TYPE)
1332 arg = adjust_temp_type (type, arg);
1333 if (!TREE_CONSTANT (arg))
1334 *non_constant_args = true;
1335 *p = build_tree_list (parms, arg);
1336 p = &TREE_CHAIN (*p);
1338 parms = TREE_CHAIN (parms);
1342 /* Variables and functions to manage constexpr call expansion context.
1343 These do not need to be marked for PCH or GC. */
1345 /* FIXME remember and print actual constant arguments. */
1346 static vec<tree> call_stack;
1347 static int call_stack_tick;
1348 static int last_cx_error_tick;
1351 push_cx_call_context (tree call)
1354 if (!EXPR_HAS_LOCATION (call))
1355 SET_EXPR_LOCATION (call, input_location);
1356 call_stack.safe_push (call);
1357 if (call_stack.length () > (unsigned) max_constexpr_depth)
1363 pop_cx_call_context (void)
1370 cx_error_context (void)
1372 vec<tree> r = vNULL;
1373 if (call_stack_tick != last_cx_error_tick
1374 && !call_stack.is_empty ())
1376 last_cx_error_tick = call_stack_tick;
1380 /* Evaluate a call T to a GCC internal function when possible and return
1381 the evaluated result or, under the control of CTX, give an error, set
1382 NON_CONSTANT_P, and return the unevaluated call T otherwise. */
1385 cxx_eval_internal_function (const constexpr_ctx *ctx, tree t,
1387 bool *non_constant_p, bool *overflow_p)
1389 enum tree_code opcode = ERROR_MARK;
1391 switch (CALL_EXPR_IFN (t))
1393 case IFN_UBSAN_NULL:
1394 case IFN_UBSAN_BOUNDS:
1395 case IFN_UBSAN_VPTR:
1396 case IFN_FALLTHROUGH:
1399 case IFN_ADD_OVERFLOW:
1402 case IFN_SUB_OVERFLOW:
1403 opcode = MINUS_EXPR;
1405 case IFN_MUL_OVERFLOW:
1410 return cxx_eval_constant_expression (ctx, CALL_EXPR_ARG (t, 0),
1411 false, non_constant_p, overflow_p);
1415 error_at (EXPR_LOC_OR_LOC (t, input_location),
1416 "call to internal function %qE", t);
1417 *non_constant_p = true;
1421 /* Evaluate constant arguments using OPCODE and return a complex
1422 number containing the result and the overflow bit. */
1423 tree arg0 = cxx_eval_constant_expression (ctx, CALL_EXPR_ARG (t, 0), lval,
1424 non_constant_p, overflow_p);
1425 tree arg1 = cxx_eval_constant_expression (ctx, CALL_EXPR_ARG (t, 1), lval,
1426 non_constant_p, overflow_p);
1428 if (TREE_CODE (arg0) == INTEGER_CST && TREE_CODE (arg1) == INTEGER_CST)
1430 location_t loc = EXPR_LOC_OR_LOC (t, input_location);
1431 tree type = TREE_TYPE (TREE_TYPE (t));
1432 tree result = fold_binary_loc (loc, opcode, type,
1433 fold_convert_loc (loc, type, arg0),
1434 fold_convert_loc (loc, type, arg1));
1436 = build_int_cst (type, arith_overflowed_p (opcode, type, arg0, arg1));
1437 /* Reset TREE_OVERFLOW to avoid warnings for the overflow. */
1438 if (TREE_OVERFLOW (result))
1439 TREE_OVERFLOW (result) = 0;
1441 return build_complex (TREE_TYPE (t), result, ovf);
1444 *non_constant_p = true;
1448 /* Clean CONSTRUCTOR_NO_IMPLICIT_ZERO from CTOR and its sub-aggregates. */
1451 clear_no_implicit_zero (tree ctor)
1453 if (CONSTRUCTOR_NO_IMPLICIT_ZERO (ctor))
1455 CONSTRUCTOR_NO_IMPLICIT_ZERO (ctor) = false;
1456 tree elt; unsigned HOST_WIDE_INT idx;
1457 FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (ctor), idx, elt)
1458 if (TREE_CODE (elt) == CONSTRUCTOR)
1459 clear_no_implicit_zero (elt);
1463 /* Subroutine of cxx_eval_constant_expression.
1464 Evaluate the call expression tree T in the context of OLD_CALL expression
1468 cxx_eval_call_expression (const constexpr_ctx *ctx, tree t,
1470 bool *non_constant_p, bool *overflow_p)
1472 location_t loc = EXPR_LOC_OR_LOC (t, input_location);
1473 tree fun = get_function_named_in_call (t);
1474 constexpr_call new_call = { NULL, NULL, NULL, 0 };
1477 if (fun == NULL_TREE)
1478 return cxx_eval_internal_function (ctx, t, lval,
1479 non_constant_p, overflow_p);
1481 if (TREE_CODE (fun) != FUNCTION_DECL)
1483 /* Might be a constexpr function pointer. */
1484 fun = cxx_eval_constant_expression (ctx, fun,
1485 /*lval*/false, non_constant_p,
1488 if (TREE_CODE (fun) == ADDR_EXPR)
1489 fun = TREE_OPERAND (fun, 0);
1491 if (TREE_CODE (fun) != FUNCTION_DECL)
1493 if (!ctx->quiet && !*non_constant_p)
1494 error_at (loc, "expression %qE does not designate a %<constexpr%> "
1496 *non_constant_p = true;
1499 if (DECL_CLONED_FUNCTION_P (fun))
1500 fun = DECL_CLONED_FUNCTION (fun);
1502 if (is_ubsan_builtin_p (fun))
1505 if (is_builtin_fn (fun))
1506 return cxx_eval_builtin_function_call (ctx, t, fun,
1507 lval, non_constant_p, overflow_p);
1508 if (!DECL_DECLARED_CONSTEXPR_P (fun))
1512 if (!lambda_static_thunk_p (fun))
1513 error_at (loc, "call to non-%<constexpr%> function %qD", fun);
1514 explain_invalid_constexpr_fn (fun);
1516 *non_constant_p = true;
1520 constexpr_ctx new_ctx = *ctx;
1521 if (DECL_CONSTRUCTOR_P (fun) && !ctx->object
1522 && TREE_CODE (t) == AGGR_INIT_EXPR)
1524 /* We want to have an initialization target for an AGGR_INIT_EXPR.
1525 If we don't already have one in CTX, use the AGGR_INIT_EXPR_SLOT. */
1526 new_ctx.object = AGGR_INIT_EXPR_SLOT (t);
1527 tree ctor = new_ctx.ctor = build_constructor (DECL_CONTEXT (fun), NULL);
1528 CONSTRUCTOR_NO_IMPLICIT_ZERO (ctor) = true;
1529 ctx->values->put (new_ctx.object, ctor);
1533 /* Shortcut trivial constructor/op=. */
1534 if (trivial_fn_p (fun))
1536 tree init = NULL_TREE;
1537 if (call_expr_nargs (t) == 2)
1538 init = convert_from_reference (get_nth_callarg (t, 1));
1539 else if (TREE_CODE (t) == AGGR_INIT_EXPR
1540 && AGGR_INIT_ZERO_FIRST (t))
1541 init = build_zero_init (DECL_CONTEXT (fun), NULL_TREE, false);
1544 tree op = get_nth_callarg (t, 0);
1545 if (is_dummy_object (op))
1548 op = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (op)), op);
1549 tree set = build2 (MODIFY_EXPR, TREE_TYPE (op), op, init);
1550 new_ctx.call = &new_call;
1551 return cxx_eval_constant_expression (&new_ctx, set, lval,
1552 non_constant_p, overflow_p);
1556 /* We can't defer instantiating the function any longer. */
1557 if (!DECL_INITIAL (fun)
1558 && DECL_TEMPLOID_INSTANTIATION (fun))
1560 location_t save_loc = input_location;
1561 input_location = loc;
1563 instantiate_decl (fun, /*defer_ok*/false, /*expl_inst*/false);
1565 input_location = save_loc;
1568 /* If in direct recursive call, optimize definition search. */
1569 if (ctx && ctx->call && ctx->call->fundef && ctx->call->fundef->decl == fun)
1570 new_call.fundef = ctx->call->fundef;
1573 new_call.fundef = retrieve_constexpr_fundef (fun);
1574 if (new_call.fundef == NULL || new_call.fundef->body == NULL
1575 || fun == current_function_decl)
1579 /* We need to check for current_function_decl here in case we're
1580 being called during cp_fold_function, because at that point
1581 DECL_INITIAL is set properly and we have a fundef but we
1582 haven't lowered invisirefs yet (c++/70344). */
1583 if (DECL_INITIAL (fun) == error_mark_node
1584 || fun == current_function_decl)
1585 error_at (loc, "%qD called in a constant expression before its "
1586 "definition is complete", fun);
1587 else if (DECL_INITIAL (fun))
1589 /* The definition of fun was somehow unsuitable. But pretend
1590 that lambda static thunks don't exist. */
1591 if (!lambda_static_thunk_p (fun))
1592 error_at (loc, "%qD called in a constant expression", fun);
1593 explain_invalid_constexpr_fn (fun);
1596 error_at (loc, "%qD used before its definition", fun);
1598 *non_constant_p = true;
1603 bool non_constant_args = false;
1604 cxx_bind_parameters_in_call (ctx, t, &new_call,
1605 non_constant_p, overflow_p, &non_constant_args);
1606 if (*non_constant_p)
1609 depth_ok = push_cx_call_context (t);
1611 tree result = NULL_TREE;
1613 constexpr_call *entry = NULL;
1614 if (depth_ok && !non_constant_args && ctx->strict)
1616 new_call.hash = iterative_hash_template_arg
1617 (new_call.bindings, constexpr_fundef_hasher::hash (new_call.fundef));
1619 /* If we have seen this call before, we are done. */
1620 maybe_initialize_constexpr_call_table ();
1621 constexpr_call **slot
1622 = constexpr_call_table->find_slot (&new_call, INSERT);
1626 /* We need to keep a pointer to the entry, not just the slot, as the
1627 slot can move in the call to cxx_eval_builtin_function_call. */
1628 *slot = entry = ggc_alloc<constexpr_call> ();
1631 /* Calls that are in progress have their result set to NULL,
1632 so that we can detect circular dependencies. */
1633 else if (entry->result == NULL)
1636 error ("call has circular dependency");
1637 *non_constant_p = true;
1638 entry->result = result = error_mark_node;
1641 result = entry->result;
1647 error ("%<constexpr%> evaluation depth exceeds maximum of %d (use "
1648 "-fconstexpr-depth= to increase the maximum)",
1649 max_constexpr_depth);
1650 *non_constant_p = true;
1651 result = error_mark_node;
1655 if (result && result != error_mark_node)
1657 else if (!DECL_SAVED_TREE (fun))
1659 /* When at_eof >= 2, cgraph has started throwing away
1660 DECL_SAVED_TREE, so fail quietly. FIXME we get here because of
1661 late code generation for VEC_INIT_EXPR, which needs to be
1662 completely reconsidered. */
1663 gcc_assert (at_eof >= 2 && ctx->quiet);
1664 *non_constant_p = true;
1668 tree body, parms, res;
1670 /* Reuse or create a new unshared copy of this function's body. */
1671 tree copy = get_fundef_copy (fun);
1672 body = TREE_PURPOSE (copy);
1673 parms = TREE_VALUE (copy);
1674 res = TREE_TYPE (copy);
1676 /* Associate the bindings with the remapped parms. */
1677 tree bound = new_call.bindings;
1678 tree remapped = parms;
1681 tree oparm = TREE_PURPOSE (bound);
1682 tree arg = TREE_VALUE (bound);
1683 gcc_assert (DECL_NAME (remapped) == DECL_NAME (oparm));
1684 /* Don't share a CONSTRUCTOR that might be changed. */
1685 arg = unshare_constructor (arg);
1686 ctx->values->put (remapped, arg);
1687 bound = TREE_CHAIN (bound);
1688 remapped = DECL_CHAIN (remapped);
1690 /* Add the RESULT_DECL to the values map, too. */
1691 tree slot = NULL_TREE;
1692 if (DECL_BY_REFERENCE (res))
1694 slot = AGGR_INIT_EXPR_SLOT (t);
1695 tree addr = build_address (slot);
1696 addr = build_nop (TREE_TYPE (res), addr);
1697 ctx->values->put (res, addr);
1698 ctx->values->put (slot, NULL_TREE);
1701 ctx->values->put (res, NULL_TREE);
1703 /* Track the callee's evaluated SAVE_EXPRs so that we can forget
1704 their values after the call. */
1705 constexpr_ctx ctx_with_save_exprs = *ctx;
1706 hash_set<tree> save_exprs;
1707 ctx_with_save_exprs.save_exprs = &save_exprs;
1708 ctx_with_save_exprs.call = &new_call;
1710 tree jump_target = NULL_TREE;
1711 cxx_eval_constant_expression (&ctx_with_save_exprs, body,
1712 lval, non_constant_p, overflow_p,
1715 if (DECL_CONSTRUCTOR_P (fun))
1716 /* This can be null for a subobject constructor call, in
1717 which case what we care about is the initialization
1718 side-effects rather than the value. We could get at the
1719 value by evaluating *this, but we don't bother; there's
1720 no need to put such a call in the hash table. */
1721 result = lval ? ctx->object : ctx->ctor;
1722 else if (VOID_TYPE_P (TREE_TYPE (res)))
1726 result = *ctx->values->get (slot ? slot : res);
1727 if (result == NULL_TREE && !*non_constant_p)
1730 error ("%<constexpr%> call flows off the end "
1732 *non_constant_p = true;
1736 /* Forget the saved values of the callee's SAVE_EXPRs. */
1737 for (hash_set<tree>::iterator iter = save_exprs.begin();
1738 iter != save_exprs.end(); ++iter)
1739 ctx_with_save_exprs.values->remove (*iter);
1741 /* Remove the parms/result from the values map. Is it worth
1742 bothering to do this when the map itself is only live for
1743 one constexpr evaluation? If so, maybe also clear out
1744 other vars from call, maybe in BIND_EXPR handling? */
1745 ctx->values->remove (res);
1747 ctx->values->remove (slot);
1748 for (tree parm = parms; parm; parm = TREE_CHAIN (parm))
1749 ctx->values->remove (parm);
1751 /* Make the unshared function copy we used available for re-use. */
1752 save_fundef_copy (fun, copy);
1755 if (result == error_mark_node)
1756 *non_constant_p = true;
1757 if (*non_constant_p || *overflow_p)
1758 result = error_mark_node;
1762 entry->result = result;
1765 /* The result of a constexpr function must be completely initialized. */
1766 if (TREE_CODE (result) == CONSTRUCTOR)
1767 clear_no_implicit_zero (result);
1769 pop_cx_call_context ();
1770 return unshare_constructor (result);
1773 /* FIXME speed this up, it's taking 16% of compile time on sieve testcase. */
1776 reduced_constant_expression_p (tree t)
1781 switch (TREE_CODE (t))
1784 /* Even if we can't lower this yet, it's constant. */
1788 /* And we need to handle PTRMEM_CST wrapped in a CONSTRUCTOR. */
1789 tree idx, val, field; unsigned HOST_WIDE_INT i;
1790 if (CONSTRUCTOR_NO_IMPLICIT_ZERO (t))
1792 if (TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
1793 /* An initialized vector would have a VECTOR_CST. */
1796 field = next_initializable_field (TYPE_FIELDS (TREE_TYPE (t)));
1800 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (t), i, idx, val)
1802 /* If VAL is null, we're in the middle of initializing this
1804 if (!reduced_constant_expression_p (val))
1810 field = next_initializable_field (DECL_CHAIN (field));
1815 else if (CONSTRUCTOR_NO_IMPLICIT_ZERO (t))
1816 /* All the fields are initialized. */
1817 CONSTRUCTOR_NO_IMPLICIT_ZERO (t) = false;
1821 /* FIXME are we calling this too much? */
1822 return initializer_constant_valid_p (t, TREE_TYPE (t)) != NULL_TREE;
1826 /* Some expressions may have constant operands but are not constant
1827 themselves, such as 1/0. Call this function to check for that
1830 We only call this in places that require an arithmetic constant, not in
1831 places where we might have a non-constant expression that can be a
1832 component of a constant expression, such as the address of a constexpr
1833 variable that might be dereferenced later. */
1836 verify_constant (tree t, bool allow_non_constant, bool *non_constant_p,
1839 if (!*non_constant_p && !reduced_constant_expression_p (t))
1841 if (!allow_non_constant)
1842 error ("%q+E is not a constant expression", t);
1843 *non_constant_p = true;
1845 if (TREE_OVERFLOW_P (t))
1847 if (!allow_non_constant)
1849 permerror (input_location, "overflow in constant expression");
1850 /* If we're being permissive (and are in an enforcing
1851 context), ignore the overflow. */
1852 if (flag_permissive)
1853 return *non_constant_p;
1857 return *non_constant_p;
1860 /* Check whether the shift operation with code CODE and type TYPE on LHS
1861 and RHS is undefined. If it is, give an error with an explanation,
1862 and return true; return false otherwise. */
1865 cxx_eval_check_shift_p (location_t loc, const constexpr_ctx *ctx,
1866 enum tree_code code, tree type, tree lhs, tree rhs)
1868 if ((code != LSHIFT_EXPR && code != RSHIFT_EXPR)
1869 || TREE_CODE (lhs) != INTEGER_CST
1870 || TREE_CODE (rhs) != INTEGER_CST)
1873 tree lhstype = TREE_TYPE (lhs);
1874 unsigned HOST_WIDE_INT uprec = TYPE_PRECISION (TREE_TYPE (lhs));
1876 /* [expr.shift] The behavior is undefined if the right operand
1877 is negative, or greater than or equal to the length in bits
1878 of the promoted left operand. */
1879 if (tree_int_cst_sgn (rhs) == -1)
1882 permerror (loc, "right operand of shift expression %q+E is negative",
1883 build2_loc (loc, code, type, lhs, rhs));
1884 return (!flag_permissive || ctx->quiet);
1886 if (compare_tree_int (rhs, uprec) >= 0)
1889 permerror (loc, "right operand of shift expression %q+E is >= than "
1890 "the precision of the left operand",
1891 build2_loc (loc, code, type, lhs, rhs));
1892 return (!flag_permissive || ctx->quiet);
1895 /* The value of E1 << E2 is E1 left-shifted E2 bit positions; [...]
1896 if E1 has a signed type and non-negative value, and E1x2^E2 is
1897 representable in the corresponding unsigned type of the result type,
1898 then that value, converted to the result type, is the resulting value;
1899 otherwise, the behavior is undefined. */
1900 if (code == LSHIFT_EXPR && !TYPE_UNSIGNED (lhstype)
1901 && (cxx_dialect >= cxx11))
1903 if (tree_int_cst_sgn (lhs) == -1)
1907 "left operand of shift expression %q+E is negative",
1908 build2_loc (loc, code, type, lhs, rhs));
1909 return (!flag_permissive || ctx->quiet);
1911 /* For signed x << y the following:
1912 (unsigned) x >> ((prec (lhs) - 1) - y)
1913 if > 1, is undefined. The right-hand side of this formula
1914 is the highest bit of the LHS that can be set (starting from 0),
1915 so that the shift doesn't overflow. We then right-shift the LHS
1916 to see whether any other bit is set making the original shift
1917 undefined -- the result is not representable in the corresponding
1919 tree t = build_int_cst (unsigned_type_node, uprec - 1);
1920 t = fold_build2 (MINUS_EXPR, unsigned_type_node, t, rhs);
1921 tree ulhs = fold_convert (unsigned_type_for (lhstype), lhs);
1922 t = fold_build2 (RSHIFT_EXPR, TREE_TYPE (ulhs), ulhs, t);
1923 if (tree_int_cst_lt (integer_one_node, t))
1926 permerror (loc, "shift expression %q+E overflows",
1927 build2_loc (loc, code, type, lhs, rhs));
1928 return (!flag_permissive || ctx->quiet);
1934 /* Subroutine of cxx_eval_constant_expression.
1935 Attempt to reduce the unary expression tree T to a compile time value.
1936 If successful, return the value. Otherwise issue a diagnostic
1937 and return error_mark_node. */
1940 cxx_eval_unary_expression (const constexpr_ctx *ctx, tree t,
1942 bool *non_constant_p, bool *overflow_p)
1945 tree orig_arg = TREE_OPERAND (t, 0);
1946 tree arg = cxx_eval_constant_expression (ctx, orig_arg, /*lval*/false,
1947 non_constant_p, overflow_p);
1948 VERIFY_CONSTANT (arg);
1949 location_t loc = EXPR_LOCATION (t);
1950 enum tree_code code = TREE_CODE (t);
1951 tree type = TREE_TYPE (t);
1952 r = fold_unary_loc (loc, code, type, arg);
1955 if (arg == orig_arg)
1958 r = build1_loc (loc, code, type, arg);
1960 VERIFY_CONSTANT (r);
1964 /* Helper function for cxx_eval_binary_expression. Try to optimize
1965 original POINTER_PLUS_EXPR T, LHS p+ RHS, return NULL_TREE if the
1966 generic folding should be used. */
1969 cxx_fold_pointer_plus_expression (const constexpr_ctx *ctx, tree t,
1970 tree lhs, tree rhs, bool *non_constant_p,
1974 if (TREE_CODE (lhs) != ADDR_EXPR)
1977 lhs = TREE_OPERAND (lhs, 0);
1979 /* &A[i] p+ j => &A[i + j] */
1980 if (TREE_CODE (lhs) == ARRAY_REF
1981 && TREE_CODE (TREE_OPERAND (lhs, 1)) == INTEGER_CST
1982 && TREE_CODE (rhs) == INTEGER_CST
1983 && TYPE_SIZE_UNIT (TREE_TYPE (lhs))
1984 && TREE_CODE (TYPE_SIZE_UNIT (TREE_TYPE (lhs))) == INTEGER_CST)
1986 tree orig_type = TREE_TYPE (t);
1987 location_t loc = EXPR_LOCATION (t);
1988 tree type = TREE_TYPE (lhs);
1990 t = fold_convert_loc (loc, ssizetype, TREE_OPERAND (lhs, 1));
1991 tree nelts = array_type_nelts_top (TREE_TYPE (TREE_OPERAND (lhs, 0)));
1992 nelts = cxx_eval_constant_expression (ctx, nelts, false, non_constant_p,
1994 if (*non_constant_p)
1996 /* Don't fold an out-of-bound access. */
1997 if (!tree_int_cst_le (t, nelts))
1999 rhs = cp_fold_convert (ssizetype, rhs);
2000 /* Don't fold if rhs can't be divided exactly by TYPE_SIZE_UNIT.
2001 constexpr int A[1]; ... (char *)&A[0] + 1 */
2002 if (!integer_zerop (fold_build2_loc (loc, TRUNC_MOD_EXPR, sizetype,
2003 rhs, TYPE_SIZE_UNIT (type))))
2005 /* Make sure to treat the second operand of POINTER_PLUS_EXPR
2007 rhs = fold_build2_loc (loc, EXACT_DIV_EXPR, ssizetype, rhs,
2008 TYPE_SIZE_UNIT (type));
2009 t = size_binop_loc (loc, PLUS_EXPR, rhs, t);
2010 t = build4_loc (loc, ARRAY_REF, type, TREE_OPERAND (lhs, 0),
2011 t, NULL_TREE, NULL_TREE);
2012 t = cp_build_addr_expr (t, tf_warning_or_error);
2013 t = cp_fold_convert (orig_type, t);
2014 return cxx_eval_constant_expression (ctx, t, /*lval*/false,
2015 non_constant_p, overflow_p);
2021 /* Subroutine of cxx_eval_constant_expression.
2022 Like cxx_eval_unary_expression, except for binary expressions. */
2025 cxx_eval_binary_expression (const constexpr_ctx *ctx, tree t,
2027 bool *non_constant_p, bool *overflow_p)
2030 tree orig_lhs = TREE_OPERAND (t, 0);
2031 tree orig_rhs = TREE_OPERAND (t, 1);
2033 lhs = cxx_eval_constant_expression (ctx, orig_lhs, /*lval*/false,
2034 non_constant_p, overflow_p);
2035 /* Don't VERIFY_CONSTANT here, it's unnecessary and will break pointer
2037 if (*non_constant_p)
2039 rhs = cxx_eval_constant_expression (ctx, orig_rhs, /*lval*/false,
2040 non_constant_p, overflow_p);
2041 if (*non_constant_p)
2044 location_t loc = EXPR_LOCATION (t);
2045 enum tree_code code = TREE_CODE (t);
2046 tree type = TREE_TYPE (t);
2048 if (code == EQ_EXPR || code == NE_EXPR)
2050 bool is_code_eq = (code == EQ_EXPR);
2052 if (TREE_CODE (lhs) == PTRMEM_CST
2053 && TREE_CODE (rhs) == PTRMEM_CST)
2054 r = constant_boolean_node (cp_tree_equal (lhs, rhs) == is_code_eq,
2056 else if ((TREE_CODE (lhs) == PTRMEM_CST
2057 || TREE_CODE (rhs) == PTRMEM_CST)
2058 && (null_member_pointer_value_p (lhs)
2059 || null_member_pointer_value_p (rhs)))
2060 r = constant_boolean_node (!is_code_eq, type);
2061 else if (TREE_CODE (lhs) == PTRMEM_CST)
2062 lhs = cplus_expand_constant (lhs);
2063 else if (TREE_CODE (rhs) == PTRMEM_CST)
2064 rhs = cplus_expand_constant (rhs);
2066 if (code == POINTER_PLUS_EXPR && !*non_constant_p
2067 && integer_zerop (lhs) && !integer_zerop (rhs))
2070 error ("arithmetic involving a null pointer in %qE", lhs);
2071 *non_constant_p = true;
2074 else if (code == POINTER_PLUS_EXPR)
2075 r = cxx_fold_pointer_plus_expression (ctx, t, lhs, rhs, non_constant_p,
2079 r = fold_binary_loc (loc, code, type, lhs, rhs);
2083 if (lhs == orig_lhs && rhs == orig_rhs)
2086 r = build2_loc (loc, code, type, lhs, rhs);
2088 else if (cxx_eval_check_shift_p (loc, ctx, code, type, lhs, rhs))
2089 *non_constant_p = true;
2090 /* Don't VERIFY_CONSTANT if this might be dealing with a pointer to
2091 a local array in a constexpr function. */
2092 bool ptr = POINTER_TYPE_P (TREE_TYPE (lhs));
2094 VERIFY_CONSTANT (r);
2098 /* Subroutine of cxx_eval_constant_expression.
2099 Attempt to evaluate condition expressions. Dead branches are not
2103 cxx_eval_conditional_expression (const constexpr_ctx *ctx, tree t,
2105 bool *non_constant_p, bool *overflow_p,
2108 tree val = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0),
2110 non_constant_p, overflow_p);
2111 VERIFY_CONSTANT (val);
2112 /* Don't VERIFY_CONSTANT the other operands. */
2113 if (integer_zerop (val))
2114 return cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 2),
2116 non_constant_p, overflow_p,
2118 return cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 1),
2120 non_constant_p, overflow_p,
2124 /* Subroutine of cxx_eval_constant_expression.
2125 Attempt to evaluate vector condition expressions. Unlike
2126 cxx_eval_conditional_expression, VEC_COND_EXPR acts like a normal
2127 ternary arithmetics operation, where all 3 arguments have to be
2128 evaluated as constants and then folding computes the result from
2132 cxx_eval_vector_conditional_expression (const constexpr_ctx *ctx, tree t,
2133 bool *non_constant_p, bool *overflow_p)
2135 tree arg1 = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0),
2137 non_constant_p, overflow_p);
2138 VERIFY_CONSTANT (arg1);
2139 tree arg2 = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 1),
2141 non_constant_p, overflow_p);
2142 VERIFY_CONSTANT (arg2);
2143 tree arg3 = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 2),
2145 non_constant_p, overflow_p);
2146 VERIFY_CONSTANT (arg3);
2147 location_t loc = EXPR_LOCATION (t);
2148 tree type = TREE_TYPE (t);
2149 tree r = fold_ternary_loc (loc, VEC_COND_EXPR, type, arg1, arg2, arg3);
2152 if (arg1 == TREE_OPERAND (t, 0)
2153 && arg2 == TREE_OPERAND (t, 1)
2154 && arg3 == TREE_OPERAND (t, 2))
2157 r = build3_loc (loc, VEC_COND_EXPR, type, arg1, arg2, arg3);
2159 VERIFY_CONSTANT (r);
2163 /* Returns less than, equal to, or greater than zero if KEY is found to be
2164 less than, to match, or to be greater than the constructor_elt's INDEX. */
2167 array_index_cmp (tree key, tree index)
2169 gcc_assert (TREE_CODE (key) == INTEGER_CST);
2171 switch (TREE_CODE (index))
2174 return tree_int_cst_compare (key, index);
2177 tree lo = TREE_OPERAND (index, 0);
2178 tree hi = TREE_OPERAND (index, 1);
2179 if (tree_int_cst_lt (key, lo))
2181 else if (tree_int_cst_lt (hi, key))
2191 /* Returns the index of the constructor_elt of ARY which matches DINDEX, or -1
2192 if none. If INSERT is true, insert a matching element rather than fail. */
2194 static HOST_WIDE_INT
2195 find_array_ctor_elt (tree ary, tree dindex, bool insert = false)
2197 if (tree_int_cst_sgn (dindex) < 0)
2200 unsigned HOST_WIDE_INT i = tree_to_uhwi (dindex);
2201 vec<constructor_elt, va_gc> *elts = CONSTRUCTOR_ELTS (ary);
2202 unsigned HOST_WIDE_INT len = vec_safe_length (elts);
2204 unsigned HOST_WIDE_INT end = len;
2205 unsigned HOST_WIDE_INT begin = 0;
2207 /* If the last element of the CONSTRUCTOR has its own index, we can assume
2208 that the same is true of the other elements and index directly. */
2211 tree cindex = (*elts)[end - 1].index;
2212 if (TREE_CODE (cindex) == INTEGER_CST
2213 && compare_tree_int (cindex, end - 1) == 0)
2222 /* Otherwise, find a matching index by means of a binary search. */
2223 while (begin != end)
2225 unsigned HOST_WIDE_INT middle = (begin + end) / 2;
2226 constructor_elt &elt = (*elts)[middle];
2227 tree idx = elt.index;
2229 int cmp = array_index_cmp (dindex, idx);
2236 if (insert && TREE_CODE (idx) == RANGE_EXPR)
2238 /* We need to split the range. */
2240 tree lo = TREE_OPERAND (idx, 0);
2241 tree hi = TREE_OPERAND (idx, 1);
2242 tree value = elt.value;
2243 dindex = fold_convert (sizetype, dindex);
2244 if (tree_int_cst_lt (lo, dindex))
2246 /* There are still some lower elts; shorten the range. */
2247 tree new_hi = int_const_binop (MINUS_EXPR, dindex,
2249 if (tree_int_cst_equal (lo, new_hi))
2250 /* Only one element left, no longer a range. */
2253 TREE_OPERAND (idx, 1) = new_hi;
2254 /* Append the element we want to insert. */
2257 e.value = unshare_constructor (value);
2258 vec_safe_insert (CONSTRUCTOR_ELTS (ary), middle, e);
2261 /* No lower elts, the range elt is now ours. */
2264 if (tree_int_cst_lt (dindex, hi))
2266 /* There are still some higher elts; append a range. */
2267 tree new_lo = int_const_binop (PLUS_EXPR, dindex,
2269 if (tree_int_cst_equal (new_lo, hi))
2272 e.index = build2 (RANGE_EXPR, sizetype, new_lo, hi);
2273 e.value = unshare_constructor (value);
2274 vec_safe_insert (CONSTRUCTOR_ELTS (ary), middle + 1, e);
2283 constructor_elt e = { dindex, NULL_TREE };
2284 vec_safe_insert (CONSTRUCTOR_ELTS (ary), end, e);
2291 /* Under the control of CTX, issue a detailed diagnostic for
2292 an out-of-bounds subscript INDEX into the expression ARRAY. */
2295 diag_array_subscript (const constexpr_ctx *ctx, tree array, tree index)
2299 tree arraytype = TREE_TYPE (array);
2301 /* Convert the unsigned array subscript to a signed integer to avoid
2302 printing huge numbers for small negative values. */
2303 tree sidx = fold_convert (ssizetype, index);
2306 if (TYPE_DOMAIN (arraytype))
2307 error ("array subscript value %qE is outside the bounds "
2308 "of array %qD of type %qT", sidx, array, arraytype);
2310 error ("non-zero array subscript %qE is used with array %qD of "
2311 "type %qT with unknown bounds", sidx, array, arraytype);
2312 inform (DECL_SOURCE_LOCATION (array), "declared here");
2314 else if (TYPE_DOMAIN (arraytype))
2315 error ("array subscript value %qE is outside the bounds "
2316 "of array type %qT", sidx, arraytype);
2318 error ("non-zero array subscript %qE is used with array of type %qT "
2319 "with unknown bounds", sidx, arraytype);
2323 /* Return the number of elements for TYPE (which is an ARRAY_TYPE or
2327 get_array_or_vector_nelts (const constexpr_ctx *ctx, tree type,
2328 bool *non_constant_p, bool *overflow_p)
2331 if (TREE_CODE (type) == ARRAY_TYPE)
2333 if (TYPE_DOMAIN (type))
2334 nelts = array_type_nelts_top (type);
2336 nelts = size_zero_node;
2338 else if (VECTOR_TYPE_P (type))
2339 nelts = size_int (TYPE_VECTOR_SUBPARTS (type));
2343 /* For VLAs, the number of elements won't be an integer constant. */
2344 nelts = cxx_eval_constant_expression (ctx, nelts, false,
2345 non_constant_p, overflow_p);
2349 /* Extract element INDEX consisting of CHARS_PER_ELT chars from
2350 STRING_CST STRING. */
2353 extract_string_elt (tree string, unsigned chars_per_elt, unsigned index)
2355 tree type = cv_unqualified (TREE_TYPE (TREE_TYPE (string)));
2358 if (chars_per_elt == 1)
2359 r = build_int_cst (type, TREE_STRING_POINTER (string)[index]);
2362 const unsigned char *ptr
2363 = ((const unsigned char *)TREE_STRING_POINTER (string)
2364 + index * chars_per_elt);
2365 r = native_interpret_expr (type, ptr, chars_per_elt);
2370 /* Subroutine of cxx_eval_constant_expression.
2371 Attempt to reduce a reference to an array slot. */
2374 cxx_eval_array_reference (const constexpr_ctx *ctx, tree t,
2376 bool *non_constant_p, bool *overflow_p)
2378 tree oldary = TREE_OPERAND (t, 0);
2379 tree ary = cxx_eval_constant_expression (ctx, oldary,
2381 non_constant_p, overflow_p);
2383 HOST_WIDE_INT i = 0;
2384 tree elem_type = NULL_TREE;
2385 unsigned len = 0, elem_nchars = 1;
2386 if (*non_constant_p)
2388 oldidx = TREE_OPERAND (t, 1);
2389 index = cxx_eval_constant_expression (ctx, oldidx,
2391 non_constant_p, overflow_p);
2392 VERIFY_CONSTANT (index);
2395 elem_type = TREE_TYPE (TREE_TYPE (ary));
2396 if (TREE_CODE (ary) == VIEW_CONVERT_EXPR
2397 && VECTOR_TYPE_P (TREE_TYPE (TREE_OPERAND (ary, 0)))
2398 && TREE_TYPE (t) == TREE_TYPE (TREE_TYPE (TREE_OPERAND (ary, 0))))
2399 ary = TREE_OPERAND (ary, 0);
2400 if (TREE_CODE (ary) == CONSTRUCTOR)
2401 len = CONSTRUCTOR_NELTS (ary);
2402 else if (TREE_CODE (ary) == STRING_CST)
2404 elem_nchars = (TYPE_PRECISION (elem_type)
2405 / TYPE_PRECISION (char_type_node));
2406 len = (unsigned) TREE_STRING_LENGTH (ary) / elem_nchars;
2408 else if (TREE_CODE (ary) == VECTOR_CST)
2409 /* We don't create variable-length VECTOR_CSTs. */
2410 len = VECTOR_CST_NELTS (ary).to_constant ();
2413 /* We can't do anything with other tree codes, so use
2414 VERIFY_CONSTANT to complain and fail. */
2415 VERIFY_CONSTANT (ary);
2419 if (!tree_fits_shwi_p (index)
2420 || (i = tree_to_shwi (index)) < 0)
2422 diag_array_subscript (ctx, ary, index);
2423 *non_constant_p = true;
2428 tree nelts = get_array_or_vector_nelts (ctx, TREE_TYPE (ary), non_constant_p,
2430 VERIFY_CONSTANT (nelts);
2432 ? !tree_int_cst_le (index, nelts)
2433 : !tree_int_cst_lt (index, nelts))
2434 || tree_int_cst_sgn (index) < 0)
2436 diag_array_subscript (ctx, ary, index);
2437 *non_constant_p = true;
2441 if (lval && ary == oldary && index == oldidx)
2444 return build4 (ARRAY_REF, TREE_TYPE (t), ary, index, NULL, NULL);
2447 if (TREE_CODE (ary) == CONSTRUCTOR)
2449 HOST_WIDE_INT ix = find_array_ctor_elt (ary, index);
2460 if (TREE_CODE (ary) == CONSTRUCTOR)
2461 r = (*CONSTRUCTOR_ELTS (ary))[i].value;
2462 else if (TREE_CODE (ary) == VECTOR_CST)
2463 r = VECTOR_CST_ELT (ary, i);
2465 r = extract_string_elt (ary, elem_nchars, i);
2468 /* Don't VERIFY_CONSTANT here. */
2471 /* Otherwise the element doesn't have a value yet. */
2476 if (TREE_CODE (ary) == CONSTRUCTOR
2477 && CONSTRUCTOR_NO_IMPLICIT_ZERO (ary))
2479 /* 'ary' is part of the aggregate initializer we're currently
2480 building; if there's no initializer for this element yet,
2483 error ("accessing uninitialized array element");
2484 *non_constant_p = true;
2488 /* If it's within the array bounds but doesn't have an explicit
2489 initializer, it's value-initialized. */
2490 tree val = build_value_init (elem_type, tf_warning_or_error);
2491 return cxx_eval_constant_expression (ctx, val, lval, non_constant_p,
2495 /* Subroutine of cxx_eval_constant_expression.
2496 Attempt to reduce a field access of a value of class type. */
2499 cxx_eval_component_reference (const constexpr_ctx *ctx, tree t,
2501 bool *non_constant_p, bool *overflow_p)
2503 unsigned HOST_WIDE_INT i;
2506 tree part = TREE_OPERAND (t, 1);
2507 tree orig_whole = TREE_OPERAND (t, 0);
2508 tree whole = cxx_eval_constant_expression (ctx, orig_whole,
2510 non_constant_p, overflow_p);
2511 if (INDIRECT_REF_P (whole)
2512 && integer_zerop (TREE_OPERAND (whole, 0)))
2515 error ("dereferencing a null pointer in %qE", orig_whole);
2516 *non_constant_p = true;
2520 if (TREE_CODE (whole) == PTRMEM_CST)
2521 whole = cplus_expand_constant (whole);
2522 if (whole == orig_whole)
2525 return fold_build3 (COMPONENT_REF, TREE_TYPE (t),
2526 whole, part, NULL_TREE);
2527 /* Don't VERIFY_CONSTANT here; we only want to check that we got a
2529 if (!*non_constant_p && TREE_CODE (whole) != CONSTRUCTOR)
2532 error ("%qE is not a constant expression", orig_whole);
2533 *non_constant_p = true;
2535 if (DECL_MUTABLE_P (part))
2538 error ("mutable %qD is not usable in a constant expression", part);
2539 *non_constant_p = true;
2541 if (*non_constant_p)
2543 bool pmf = TYPE_PTRMEMFUNC_P (TREE_TYPE (whole));
2544 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (whole), i, field, value)
2546 /* Use name match for PMF fields, as a variant will have a
2547 different FIELD_DECL with a different type. */
2548 if (pmf ? DECL_NAME (field) == DECL_NAME (part)
2554 /* We're in the middle of initializing it. */
2558 if (TREE_CODE (TREE_TYPE (whole)) == UNION_TYPE
2559 && CONSTRUCTOR_NELTS (whole) > 0)
2561 /* DR 1188 says we don't have to deal with this. */
2563 error ("accessing %qD member instead of initialized %qD member in "
2564 "constant expression", part, CONSTRUCTOR_ELT (whole, 0)->index);
2565 *non_constant_p = true;
2569 /* We only create a CONSTRUCTOR for a subobject when we modify it, so empty
2570 classes never get represented; throw together a value now. */
2571 if (is_really_empty_class (TREE_TYPE (t)))
2572 return build_constructor (TREE_TYPE (t), NULL);
2574 gcc_assert (DECL_CONTEXT (part) == TYPE_MAIN_VARIANT (TREE_TYPE (whole)));
2576 if (CONSTRUCTOR_NO_IMPLICIT_ZERO (whole))
2578 /* 'whole' is part of the aggregate initializer we're currently
2579 building; if there's no initializer for this member yet, that's an
2582 error ("accessing uninitialized member %qD", part);
2583 *non_constant_p = true;
2587 /* If there's no explicit init for this field, it's value-initialized. */
2588 value = build_value_init (TREE_TYPE (t), tf_warning_or_error);
2589 return cxx_eval_constant_expression (ctx, value,
2591 non_constant_p, overflow_p);
2594 /* Subroutine of cxx_eval_constant_expression.
2595 Attempt to reduce a field access of a value of class type that is
2596 expressed as a BIT_FIELD_REF. */
2599 cxx_eval_bit_field_ref (const constexpr_ctx *ctx, tree t,
2601 bool *non_constant_p, bool *overflow_p)
2603 tree orig_whole = TREE_OPERAND (t, 0);
2604 tree retval, fldval, utype, mask;
2605 bool fld_seen = false;
2606 HOST_WIDE_INT istart, isize;
2607 tree whole = cxx_eval_constant_expression (ctx, orig_whole,
2609 non_constant_p, overflow_p);
2610 tree start, field, value;
2611 unsigned HOST_WIDE_INT i;
2613 if (whole == orig_whole)
2615 /* Don't VERIFY_CONSTANT here; we only want to check that we got a
2617 if (!*non_constant_p
2618 && TREE_CODE (whole) != VECTOR_CST
2619 && TREE_CODE (whole) != CONSTRUCTOR)
2622 error ("%qE is not a constant expression", orig_whole);
2623 *non_constant_p = true;
2625 if (*non_constant_p)
2628 if (TREE_CODE (whole) == VECTOR_CST)
2629 return fold_ternary (BIT_FIELD_REF, TREE_TYPE (t), whole,
2630 TREE_OPERAND (t, 1), TREE_OPERAND (t, 2));
2632 start = TREE_OPERAND (t, 2);
2633 istart = tree_to_shwi (start);
2634 isize = tree_to_shwi (TREE_OPERAND (t, 1));
2635 utype = TREE_TYPE (t);
2636 if (!TYPE_UNSIGNED (utype))
2637 utype = build_nonstandard_integer_type (TYPE_PRECISION (utype), 1);
2638 retval = build_int_cst (utype, 0);
2639 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (whole), i, field, value)
2641 tree bitpos = bit_position (field);
2642 if (bitpos == start && DECL_SIZE (field) == TREE_OPERAND (t, 1))
2644 if (TREE_CODE (TREE_TYPE (field)) == INTEGER_TYPE
2645 && TREE_CODE (value) == INTEGER_CST
2646 && tree_fits_shwi_p (bitpos)
2647 && tree_fits_shwi_p (DECL_SIZE (field)))
2649 HOST_WIDE_INT bit = tree_to_shwi (bitpos);
2650 HOST_WIDE_INT sz = tree_to_shwi (DECL_SIZE (field));
2651 HOST_WIDE_INT shift;
2652 if (bit >= istart && bit + sz <= istart + isize)
2654 fldval = fold_convert (utype, value);
2655 mask = build_int_cst_type (utype, -1);
2656 mask = fold_build2 (LSHIFT_EXPR, utype, mask,
2657 size_int (TYPE_PRECISION (utype) - sz));
2658 mask = fold_build2 (RSHIFT_EXPR, utype, mask,
2659 size_int (TYPE_PRECISION (utype) - sz));
2660 fldval = fold_build2 (BIT_AND_EXPR, utype, fldval, mask);
2661 shift = bit - istart;
2662 if (BYTES_BIG_ENDIAN)
2663 shift = TYPE_PRECISION (utype) - shift - sz;
2664 fldval = fold_build2 (LSHIFT_EXPR, utype, fldval,
2666 retval = fold_build2 (BIT_IOR_EXPR, utype, retval, fldval);
2672 return fold_convert (TREE_TYPE (t), retval);
2674 return error_mark_node;
2677 /* Subroutine of cxx_eval_constant_expression.
2678 Evaluate a short-circuited logical expression T in the context
2679 of a given constexpr CALL. BAILOUT_VALUE is the value for
2680 early return. CONTINUE_VALUE is used here purely for
2681 sanity check purposes. */
2684 cxx_eval_logical_expression (const constexpr_ctx *ctx, tree t,
2685 tree bailout_value, tree continue_value,
2687 bool *non_constant_p, bool *overflow_p)
2690 tree lhs = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0),
2692 non_constant_p, overflow_p);
2693 VERIFY_CONSTANT (lhs);
2694 if (tree_int_cst_equal (lhs, bailout_value))
2696 gcc_assert (tree_int_cst_equal (lhs, continue_value));
2697 r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 1),
2698 lval, non_constant_p,
2700 VERIFY_CONSTANT (r);
2704 /* REF is a COMPONENT_REF designating a particular field. V is a vector of
2705 CONSTRUCTOR elements to initialize (part of) an object containing that
2706 field. Return a pointer to the constructor_elt corresponding to the
2707 initialization of the field. */
2709 static constructor_elt *
2710 base_field_constructor_elt (vec<constructor_elt, va_gc> *v, tree ref)
2712 tree aggr = TREE_OPERAND (ref, 0);
2713 tree field = TREE_OPERAND (ref, 1);
2715 constructor_elt *ce;
2717 gcc_assert (TREE_CODE (ref) == COMPONENT_REF);
2719 if (TREE_CODE (aggr) == COMPONENT_REF)
2721 constructor_elt *base_ce
2722 = base_field_constructor_elt (v, aggr);
2723 v = CONSTRUCTOR_ELTS (base_ce->value);
2726 for (i = 0; vec_safe_iterate (v, i, &ce); ++i)
2727 if (ce->index == field)
2734 /* Some of the expressions fed to the constexpr mechanism are calls to
2735 constructors, which have type void. In that case, return the type being
2736 initialized by the constructor. */
2739 initialized_type (tree t)
2743 tree type = cv_unqualified (TREE_TYPE (t));
2744 if (TREE_CODE (t) == CALL_EXPR || TREE_CODE (t) == AGGR_INIT_EXPR)
2746 /* A constructor call has void type, so we need to look deeper. */
2747 tree fn = get_function_named_in_call (t);
2748 if (fn && TREE_CODE (fn) == FUNCTION_DECL
2749 && DECL_CXX_CONSTRUCTOR_P (fn))
2750 type = DECL_CONTEXT (fn);
2755 /* We're about to initialize element INDEX of an array or class from VALUE.
2756 Set up NEW_CTX appropriately by adjusting .object to refer to the
2757 subobject and creating a new CONSTRUCTOR if the element is itself
2758 a class or array. */
2761 init_subob_ctx (const constexpr_ctx *ctx, constexpr_ctx &new_ctx,
2762 tree index, tree &value)
2766 if (index && TREE_CODE (index) != INTEGER_CST
2767 && TREE_CODE (index) != FIELD_DECL)
2768 /* This won't have an element in the new CONSTRUCTOR. */
2771 tree type = initialized_type (value);
2772 if (!AGGREGATE_TYPE_P (type) && !VECTOR_TYPE_P (type))
2773 /* A non-aggregate member doesn't get its own CONSTRUCTOR. */
2776 /* The sub-aggregate initializer might contain a placeholder;
2777 update object to refer to the subobject and ctor to refer to
2778 the (newly created) sub-initializer. */
2780 new_ctx.object = build_ctor_subob_ref (index, type, ctx->object);
2781 tree elt = build_constructor (type, NULL);
2782 CONSTRUCTOR_NO_IMPLICIT_ZERO (elt) = true;
2785 if (TREE_CODE (value) == TARGET_EXPR)
2786 /* Avoid creating another CONSTRUCTOR when we expand the TARGET_EXPR. */
2787 value = TARGET_EXPR_INITIAL (value);
2790 /* We're about to process an initializer for a class or array TYPE. Make
2791 sure that CTX is set up appropriately. */
2794 verify_ctor_sanity (const constexpr_ctx *ctx, tree type)
2796 /* We don't bother building a ctor for an empty base subobject. */
2797 if (is_empty_class (type))
2800 /* We're in the middle of an initializer that might involve placeholders;
2801 our caller should have created a CONSTRUCTOR for us to put the
2802 initializer into. We will either return that constructor or T. */
2803 gcc_assert (ctx->ctor);
2804 gcc_assert (same_type_ignoring_top_level_qualifiers_p
2805 (type, TREE_TYPE (ctx->ctor)));
2806 /* We used to check that ctx->ctor was empty, but that isn't the case when
2807 the object is zero-initialized before calling the constructor. */
2810 tree otype = TREE_TYPE (ctx->object);
2811 gcc_assert (same_type_ignoring_top_level_qualifiers_p (type, otype)
2812 /* Handle flexible array members. */
2813 || (TREE_CODE (otype) == ARRAY_TYPE
2814 && TYPE_DOMAIN (otype) == NULL_TREE
2815 && TREE_CODE (type) == ARRAY_TYPE
2816 && (same_type_ignoring_top_level_qualifiers_p
2817 (TREE_TYPE (type), TREE_TYPE (otype)))));
2819 gcc_assert (!ctx->object || !DECL_P (ctx->object)
2820 || *(ctx->values->get (ctx->object)) == ctx->ctor);
2823 /* Subroutine of cxx_eval_constant_expression.
2824 The expression tree T denotes a C-style array or a C-style
2825 aggregate. Reduce it to a constant expression. */
2828 cxx_eval_bare_aggregate (const constexpr_ctx *ctx, tree t,
2830 bool *non_constant_p, bool *overflow_p)
2832 vec<constructor_elt, va_gc> *v = CONSTRUCTOR_ELTS (t);
2833 bool changed = false;
2834 gcc_assert (!BRACE_ENCLOSED_INITIALIZER_P (t));
2835 tree type = TREE_TYPE (t);
2837 constexpr_ctx new_ctx;
2838 if (TYPE_PTRMEMFUNC_P (type) || VECTOR_TYPE_P (type))
2840 /* We don't really need the ctx->ctor business for a PMF or
2841 vector, but it's simpler to use the same code. */
2843 new_ctx.ctor = build_constructor (type, NULL);
2844 new_ctx.object = NULL_TREE;
2847 verify_ctor_sanity (ctx, type);
2848 vec<constructor_elt, va_gc> **p = &CONSTRUCTOR_ELTS (ctx->ctor);
2849 vec_alloc (*p, vec_safe_length (v));
2853 bool constant_p = true;
2854 bool side_effects_p = false;
2855 FOR_EACH_CONSTRUCTOR_ELT (v, i, index, value)
2857 tree orig_value = value;
2858 init_subob_ctx (ctx, new_ctx, index, value);
2859 if (new_ctx.ctor != ctx->ctor)
2860 /* If we built a new CONSTRUCTOR, attach it now so that other
2861 initializers can refer to it. */
2862 CONSTRUCTOR_APPEND_ELT (*p, index, new_ctx.ctor);
2863 tree elt = cxx_eval_constant_expression (&new_ctx, value,
2865 non_constant_p, overflow_p);
2866 /* Don't VERIFY_CONSTANT here. */
2867 if (ctx->quiet && *non_constant_p)
2869 if (elt != orig_value)
2872 if (!TREE_CONSTANT (elt))
2874 if (TREE_SIDE_EFFECTS (elt))
2875 side_effects_p = true;
2876 if (index && TREE_CODE (index) == COMPONENT_REF)
2878 /* This is an initialization of a vfield inside a base
2879 subaggregate that we already initialized; push this
2880 initialization into the previous initialization. */
2881 constructor_elt *inner = base_field_constructor_elt (*p, index);
2886 && (TREE_CODE (index) == NOP_EXPR
2887 || TREE_CODE (index) == POINTER_PLUS_EXPR))
2889 /* This is an initializer for an empty base; now that we've
2890 checked that it's constant, we can ignore it. */
2891 gcc_assert (is_empty_class (TREE_TYPE (TREE_TYPE (index))));
2896 if (new_ctx.ctor != ctx->ctor)
2898 /* We appended this element above; update the value. */
2899 gcc_assert ((*p)->last().index == index);
2900 (*p)->last().value = elt;
2903 CONSTRUCTOR_APPEND_ELT (*p, index, elt);
2904 /* Adding or replacing an element might change the ctor's flags. */
2905 TREE_CONSTANT (ctx->ctor) = constant_p;
2906 TREE_SIDE_EFFECTS (ctx->ctor) = side_effects_p;
2909 if (*non_constant_p || !changed)
2912 /* We're done building this CONSTRUCTOR, so now we can interpret an
2913 element without an explicit initializer as value-initialized. */
2914 CONSTRUCTOR_NO_IMPLICIT_ZERO (t) = false;
2915 TREE_CONSTANT (t) = constant_p;
2916 TREE_SIDE_EFFECTS (t) = side_effects_p;
2917 if (VECTOR_TYPE_P (type))
2922 /* Subroutine of cxx_eval_constant_expression.
2923 The expression tree T is a VEC_INIT_EXPR which denotes the desired
2924 initialization of a non-static data member of array type. Reduce it to a
2927 Note that apart from value-initialization (when VALUE_INIT is true),
2928 this is only intended to support value-initialization and the
2929 initializations done by defaulted constructors for classes with
2930 non-static data members of array type. In this case, VEC_INIT_EXPR_INIT
2931 will either be NULL_TREE for the default constructor, or a COMPONENT_REF
2932 for the copy/move constructor. */
2935 cxx_eval_vec_init_1 (const constexpr_ctx *ctx, tree atype, tree init,
2936 bool value_init, bool lval,
2937 bool *non_constant_p, bool *overflow_p)
2939 tree elttype = TREE_TYPE (atype);
2940 verify_ctor_sanity (ctx, atype);
2941 vec<constructor_elt, va_gc> **p = &CONSTRUCTOR_ELTS (ctx->ctor);
2942 bool pre_init = false;
2943 unsigned HOST_WIDE_INT i;
2945 /* For the default constructor, build up a call to the default
2946 constructor of the element type. We only need to handle class types
2947 here, as for a constructor to be constexpr, all members must be
2948 initialized, which for a defaulted default constructor means they must
2949 be of a class type with a constexpr default constructor. */
2950 if (TREE_CODE (elttype) == ARRAY_TYPE)
2951 /* We only do this at the lowest level. */;
2952 else if (value_init)
2954 init = build_value_init (elttype, tf_warning_or_error);
2959 vec<tree, va_gc> *argvec = make_tree_vector ();
2960 init = build_special_member_call (NULL_TREE, complete_ctor_identifier,
2961 &argvec, elttype, LOOKUP_NORMAL,
2962 tf_warning_or_error);
2963 release_tree_vector (argvec);
2964 init = build_aggr_init_expr (TREE_TYPE (init), init);
2968 tree nelts = get_array_or_vector_nelts (ctx, atype, non_constant_p,
2970 unsigned HOST_WIDE_INT max = tree_to_uhwi (nelts);
2971 for (i = 0; i < max; ++i)
2973 tree idx = build_int_cst (size_type_node, i);
2976 constexpr_ctx new_ctx;
2977 init_subob_ctx (ctx, new_ctx, idx, pre_init ? init : elttype);
2978 if (new_ctx.ctor != ctx->ctor)
2979 CONSTRUCTOR_APPEND_ELT (*p, idx, new_ctx.ctor);
2980 if (TREE_CODE (elttype) == ARRAY_TYPE)
2982 /* A multidimensional array; recurse. */
2983 if (value_init || init == NULL_TREE)
2985 eltinit = NULL_TREE;
2989 eltinit = cp_build_array_ref (input_location, init, idx,
2990 tf_warning_or_error);
2991 eltinit = cxx_eval_vec_init_1 (&new_ctx, elttype, eltinit, value_init,
2993 non_constant_p, overflow_p);
2997 /* Initializing an element using value or default initialization
2998 we just pre-built above. */
2999 if (init == void_node)
3000 /* Trivial default-init, don't do anything to the CONSTRUCTOR. */
3002 eltinit = cxx_eval_constant_expression (&new_ctx, init, lval,
3003 non_constant_p, overflow_p);
3008 /* Copying an element. */
3009 gcc_assert (same_type_ignoring_top_level_qualifiers_p
3010 (atype, TREE_TYPE (init)));
3011 eltinit = cp_build_array_ref (input_location, init, idx,
3012 tf_warning_or_error);
3013 if (!lvalue_p (init))
3014 eltinit = move (eltinit);
3015 eltinit = force_rvalue (eltinit, tf_warning_or_error);
3016 eltinit = cxx_eval_constant_expression (&new_ctx, eltinit, lval,
3017 non_constant_p, overflow_p);
3019 if (*non_constant_p && !ctx->quiet)
3021 if (new_ctx.ctor != ctx->ctor)
3023 /* We appended this element above; update the value. */
3024 gcc_assert ((*p)->last().index == idx);
3025 (*p)->last().value = eltinit;
3028 CONSTRUCTOR_APPEND_ELT (*p, idx, eltinit);
3029 /* Reuse the result of cxx_eval_constant_expression call
3030 from the first iteration to all others if it is a constant
3031 initializer that doesn't require relocations. */
3034 && (eltinit == NULL_TREE
3035 || (initializer_constant_valid_p (eltinit, TREE_TYPE (eltinit))
3036 == null_pointer_node)))
3038 if (new_ctx.ctor != ctx->ctor)
3039 eltinit = new_ctx.ctor;
3040 tree range = build2 (RANGE_EXPR, size_type_node,
3041 build_int_cst (size_type_node, 1),
3042 build_int_cst (size_type_node, max - 1));
3043 CONSTRUCTOR_APPEND_ELT (*p, range, unshare_constructor (eltinit));
3047 vec_safe_reserve (*p, max);
3050 if (!*non_constant_p)
3053 CONSTRUCTOR_NO_IMPLICIT_ZERO (init) = false;
3059 cxx_eval_vec_init (const constexpr_ctx *ctx, tree t,
3061 bool *non_constant_p, bool *overflow_p)
3063 tree atype = TREE_TYPE (t);
3064 tree init = VEC_INIT_EXPR_INIT (t);
3065 tree r = cxx_eval_vec_init_1 (ctx, atype, init,
3066 VEC_INIT_EXPR_VALUE_INIT (t),
3067 lval, non_constant_p, overflow_p);
3068 if (*non_constant_p)
3074 /* A less strict version of fold_indirect_ref_1, which requires cv-quals to
3075 match. We want to be less strict for simple *& folding; if we have a
3076 non-const temporary that we access through a const pointer, that should
3077 work. We handle this here rather than change fold_indirect_ref_1
3078 because we're dealing with things like ADDR_EXPR of INTEGER_CST which
3079 don't really make sense outside of constant expression evaluation. Also
3080 we want to allow folding to COMPONENT_REF, which could cause trouble
3081 with TBAA in fold_indirect_ref_1.
3083 Try to keep this function synced with fold_indirect_ref_1. */
3086 cxx_fold_indirect_ref (location_t loc, tree type, tree op0, bool *empty_base)
3090 poly_uint64 const_op01;
3093 subtype = TREE_TYPE (sub);
3094 if (!POINTER_TYPE_P (subtype))
3097 if (TREE_CODE (sub) == ADDR_EXPR)
3099 tree op = TREE_OPERAND (sub, 0);
3100 tree optype = TREE_TYPE (op);
3102 /* *&CONST_DECL -> to the value of the const decl. */
3103 if (TREE_CODE (op) == CONST_DECL)
3104 return DECL_INITIAL (op);
3105 /* *&p => p; make sure to handle *&"str"[cst] here. */
3106 if (same_type_ignoring_top_level_qualifiers_p (optype, type)
3107 /* Also handle the case where the desired type is an array of unknown
3108 bounds because the variable has had its bounds deduced since the
3109 ADDR_EXPR was created. */
3110 || (TREE_CODE (type) == ARRAY_TYPE
3111 && TREE_CODE (optype) == ARRAY_TYPE
3112 && TYPE_DOMAIN (type) == NULL_TREE
3113 && same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (optype),
3116 tree fop = fold_read_from_constant_string (op);
3122 /* *(foo *)&fooarray => fooarray[0] */
3123 else if (TREE_CODE (optype) == ARRAY_TYPE
3124 && (same_type_ignoring_top_level_qualifiers_p
3125 (type, TREE_TYPE (optype))))
3127 tree type_domain = TYPE_DOMAIN (optype);
3128 tree min_val = size_zero_node;
3129 if (type_domain && TYPE_MIN_VALUE (type_domain))
3130 min_val = TYPE_MIN_VALUE (type_domain);
3131 return build4_loc (loc, ARRAY_REF, type, op, min_val,
3132 NULL_TREE, NULL_TREE);
3134 /* *(foo *)&complexfoo => __real__ complexfoo */
3135 else if (TREE_CODE (optype) == COMPLEX_TYPE
3136 && (same_type_ignoring_top_level_qualifiers_p
3137 (type, TREE_TYPE (optype))))
3138 return fold_build1_loc (loc, REALPART_EXPR, type, op);
3139 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
3140 else if (VECTOR_TYPE_P (optype)
3141 && (same_type_ignoring_top_level_qualifiers_p
3142 (type, TREE_TYPE (optype))))
3144 tree part_width = TYPE_SIZE (type);
3145 tree index = bitsize_int (0);
3146 return fold_build3_loc (loc, BIT_FIELD_REF, type, op, part_width,
3149 /* Also handle conversion to an empty base class, which
3150 is represented with a NOP_EXPR. */
3151 else if (is_empty_class (type)
3152 && CLASS_TYPE_P (optype)
3153 && DERIVED_FROM_P (type, optype))
3158 /* *(foo *)&struct_with_foo_field => COMPONENT_REF */
3159 else if (RECORD_OR_UNION_TYPE_P (optype))
3161 tree field = TYPE_FIELDS (optype);
3162 for (; field; field = DECL_CHAIN (field))
3163 if (TREE_CODE (field) == FIELD_DECL
3164 && TREE_TYPE (field) != error_mark_node
3165 && integer_zerop (byte_position (field))
3166 && (same_type_ignoring_top_level_qualifiers_p
3167 (TREE_TYPE (field), type)))
3168 return fold_build3 (COMPONENT_REF, type, op, field, NULL_TREE);
3171 else if (TREE_CODE (sub) == POINTER_PLUS_EXPR
3172 && poly_int_tree_p (TREE_OPERAND (sub, 1), &const_op01))
3174 tree op00 = TREE_OPERAND (sub, 0);
3175 tree op01 = TREE_OPERAND (sub, 1);
3178 if (TREE_CODE (op00) == ADDR_EXPR)
3181 op00 = TREE_OPERAND (op00, 0);
3182 op00type = TREE_TYPE (op00);
3184 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
3185 if (VECTOR_TYPE_P (op00type)
3186 && same_type_ignoring_top_level_qualifiers_p
3187 (type, TREE_TYPE (op00type))
3188 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
3189 but we want to treat offsets with MSB set as negative.
3190 For the code below negative offsets are invalid and
3191 TYPE_SIZE of the element is something unsigned, so
3192 check whether op01 fits into poly_int64, which implies
3193 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
3194 then just use poly_uint64 because we want to treat the
3195 value as unsigned. */
3196 && tree_fits_poly_int64_p (op01))
3198 tree part_width = TYPE_SIZE (type);
3199 poly_uint64 max_offset
3200 = (tree_to_uhwi (part_width) / BITS_PER_UNIT
3201 * TYPE_VECTOR_SUBPARTS (op00type));
3202 if (known_lt (const_op01, max_offset))
3204 tree index = bitsize_int (const_op01 * BITS_PER_UNIT);
3205 return fold_build3_loc (loc,
3206 BIT_FIELD_REF, type, op00,
3210 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
3211 else if (TREE_CODE (op00type) == COMPLEX_TYPE
3212 && (same_type_ignoring_top_level_qualifiers_p
3213 (type, TREE_TYPE (op00type))))
3215 if (known_eq (wi::to_poly_offset (TYPE_SIZE_UNIT (type)),
3217 return fold_build1_loc (loc, IMAGPART_EXPR, type, op00);
3219 /* ((foo *)&fooarray)[1] => fooarray[1] */
3220 else if (TREE_CODE (op00type) == ARRAY_TYPE
3221 && (same_type_ignoring_top_level_qualifiers_p
3222 (type, TREE_TYPE (op00type))))
3224 tree type_domain = TYPE_DOMAIN (op00type);
3225 tree min_val = size_zero_node;
3226 if (type_domain && TYPE_MIN_VALUE (type_domain))
3227 min_val = TYPE_MIN_VALUE (type_domain);
3228 offset_int off = wi::to_offset (op01);
3229 offset_int el_sz = wi::to_offset (TYPE_SIZE_UNIT (type));
3230 offset_int remainder;
3231 off = wi::divmod_trunc (off, el_sz, SIGNED, &remainder);
3232 if (remainder == 0 && TREE_CODE (min_val) == INTEGER_CST)
3234 off = off + wi::to_offset (min_val);
3235 op01 = wide_int_to_tree (sizetype, off);
3236 return build4_loc (loc, ARRAY_REF, type, op00, op01,
3237 NULL_TREE, NULL_TREE);
3240 /* Also handle conversion to an empty base class, which
3241 is represented with a NOP_EXPR. */
3242 else if (is_empty_class (type)
3243 && CLASS_TYPE_P (op00type)
3244 && DERIVED_FROM_P (type, op00type))
3249 /* ((foo *)&struct_with_foo_field)[1] => COMPONENT_REF */
3250 else if (RECORD_OR_UNION_TYPE_P (op00type))
3252 tree field = TYPE_FIELDS (op00type);
3253 for (; field; field = DECL_CHAIN (field))
3254 if (TREE_CODE (field) == FIELD_DECL
3255 && TREE_TYPE (field) != error_mark_node
3256 && tree_int_cst_equal (byte_position (field), op01)
3257 && (same_type_ignoring_top_level_qualifiers_p
3258 (TREE_TYPE (field), type)))
3259 return fold_build3 (COMPONENT_REF, type, op00,
3264 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
3265 else if (TREE_CODE (TREE_TYPE (subtype)) == ARRAY_TYPE
3266 && (same_type_ignoring_top_level_qualifiers_p
3267 (type, TREE_TYPE (TREE_TYPE (subtype)))))
3270 tree min_val = size_zero_node;
3272 = cxx_fold_indirect_ref (loc, TREE_TYPE (subtype), sub, NULL);
3276 sub = build1_loc (loc, INDIRECT_REF, TREE_TYPE (subtype), sub);
3277 type_domain = TYPE_DOMAIN (TREE_TYPE (sub));
3278 if (type_domain && TYPE_MIN_VALUE (type_domain))
3279 min_val = TYPE_MIN_VALUE (type_domain);
3280 return build4_loc (loc, ARRAY_REF, type, sub, min_val, NULL_TREE,
3288 cxx_eval_indirect_ref (const constexpr_ctx *ctx, tree t,
3290 bool *non_constant_p, bool *overflow_p)
3292 tree orig_op0 = TREE_OPERAND (t, 0);
3293 bool empty_base = false;
3295 /* We can handle a MEM_REF like an INDIRECT_REF, if MEM_REF's second
3296 operand is an integer-zero. Otherwise reject the MEM_REF for now. */
3298 if (TREE_CODE (t) == MEM_REF
3299 && (!TREE_OPERAND (t, 1) || !integer_zerop (TREE_OPERAND (t, 1))))
3301 gcc_assert (ctx->quiet);
3302 *non_constant_p = true;
3306 /* First try to simplify it directly. */
3307 tree r = cxx_fold_indirect_ref (EXPR_LOCATION (t), TREE_TYPE (t), orig_op0,
3311 /* If that didn't work, evaluate the operand first. */
3312 tree op0 = cxx_eval_constant_expression (ctx, orig_op0,
3313 /*lval*/false, non_constant_p,
3315 /* Don't VERIFY_CONSTANT here. */
3316 if (*non_constant_p)
3319 if (!lval && integer_zerop (op0))
3322 error ("dereferencing a null pointer");
3323 *non_constant_p = true;
3327 r = cxx_fold_indirect_ref (EXPR_LOCATION (t), TREE_TYPE (t), op0,
3331 /* We couldn't fold to a constant value. Make sure it's not
3332 something we should have been able to fold. */
3335 if (TREE_CODE (sub) == ADDR_EXPR)
3337 gcc_assert (!same_type_ignoring_top_level_qualifiers_p
3338 (TREE_TYPE (TREE_TYPE (sub)), TREE_TYPE (t)));
3339 /* DR 1188 says we don't have to deal with this. */
3341 error ("accessing value of %qE through a %qT glvalue in a "
3342 "constant expression", build_fold_indirect_ref (sub),
3344 *non_constant_p = true;
3348 if (lval && op0 != orig_op0)
3349 return build1 (INDIRECT_REF, TREE_TYPE (t), op0);
3351 VERIFY_CONSTANT (t);
3356 r = cxx_eval_constant_expression (ctx, r,
3357 lval, non_constant_p, overflow_p);
3358 if (*non_constant_p)
3361 /* If we're pulling out the value of an empty base, just return an empty
3363 if (empty_base && !lval)
3365 r = build_constructor (TREE_TYPE (t), NULL);
3366 TREE_CONSTANT (r) = true;
3372 /* Complain about R, a VAR_DECL, not being usable in a constant expression.
3373 Shared between potential_constant_expression and
3374 cxx_eval_constant_expression. */
3377 non_const_var_error (tree r)
3379 tree type = TREE_TYPE (r);
3380 error ("the value of %qD is not usable in a constant "
3382 /* Avoid error cascade. */
3383 if (DECL_INITIAL (r) == error_mark_node)
3385 if (DECL_DECLARED_CONSTEXPR_P (r))
3386 inform (DECL_SOURCE_LOCATION (r),
3387 "%qD used in its own initializer", r);
3388 else if (INTEGRAL_OR_ENUMERATION_TYPE_P (type))
3390 if (!CP_TYPE_CONST_P (type))
3391 inform (DECL_SOURCE_LOCATION (r),
3392 "%q#D is not const", r);
3393 else if (CP_TYPE_VOLATILE_P (type))
3394 inform (DECL_SOURCE_LOCATION (r),
3395 "%q#D is volatile", r);
3396 else if (!DECL_INITIAL (r)
3397 || !TREE_CONSTANT (DECL_INITIAL (r))
3398 || !DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (r))
3399 inform (DECL_SOURCE_LOCATION (r),
3400 "%qD was not initialized with a constant "
3405 else if (TREE_CODE (type) == REFERENCE_TYPE)
3406 inform (DECL_SOURCE_LOCATION (r),
3407 "%qD was not initialized with a constant "
3411 if (cxx_dialect >= cxx11 && !DECL_DECLARED_CONSTEXPR_P (r))
3412 inform (DECL_SOURCE_LOCATION (r),
3413 "%qD was not declared %<constexpr%>", r);
3415 inform (DECL_SOURCE_LOCATION (r),
3416 "%qD does not have integral or enumeration type",
3421 /* Subroutine of cxx_eval_constant_expression.
3422 Like cxx_eval_unary_expression, except for trinary expressions. */
3425 cxx_eval_trinary_expression (const constexpr_ctx *ctx, tree t,
3427 bool *non_constant_p, bool *overflow_p)
3433 for (i = 0; i < 3; i++)
3435 args[i] = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, i),
3437 non_constant_p, overflow_p);
3438 VERIFY_CONSTANT (args[i]);
3441 val = fold_ternary_loc (EXPR_LOCATION (t), TREE_CODE (t), TREE_TYPE (t),
3442 args[0], args[1], args[2]);
3443 if (val == NULL_TREE)
3445 VERIFY_CONSTANT (val);
3449 /* True if T was declared in a function declared to be constexpr, and
3450 therefore potentially constant in C++14. */
3453 var_in_constexpr_fn (tree t)
3455 tree ctx = DECL_CONTEXT (t);
3456 return (ctx && TREE_CODE (ctx) == FUNCTION_DECL
3457 && DECL_DECLARED_CONSTEXPR_P (ctx));
3460 /* True if T was declared in a function that might be constexpr: either a
3461 function that was declared constexpr, or a C++17 lambda op(). */
3464 var_in_maybe_constexpr_fn (tree t)
3466 if (cxx_dialect >= cxx17
3467 && DECL_FUNCTION_SCOPE_P (t)
3468 && LAMBDA_FUNCTION_P (DECL_CONTEXT (t)))
3470 return var_in_constexpr_fn (t);
3473 /* We're assigning INIT to TARGET. In do_build_copy_constructor and
3474 build_over_call we implement trivial copy of a class with tail padding using
3475 assignment of character arrays, which is valid in normal code, but not in
3476 constexpr evaluation. We don't need to worry about clobbering tail padding
3477 in constexpr evaluation, so strip the type punning. */
3480 maybe_simplify_trivial_copy (tree &target, tree &init)
3482 if (TREE_CODE (target) == MEM_REF
3483 && TREE_CODE (init) == MEM_REF
3484 && TREE_TYPE (target) == TREE_TYPE (init)
3485 && TREE_CODE (TREE_TYPE (target)) == ARRAY_TYPE
3486 && TREE_TYPE (TREE_TYPE (target)) == unsigned_char_type_node)
3488 target = build_fold_indirect_ref (TREE_OPERAND (target, 0));
3489 init = build_fold_indirect_ref (TREE_OPERAND (init, 0));
3493 /* Evaluate an INIT_EXPR or MODIFY_EXPR. */
3496 cxx_eval_store_expression (const constexpr_ctx *ctx, tree t,
3498 bool *non_constant_p, bool *overflow_p)
3500 constexpr_ctx new_ctx = *ctx;
3502 tree init = TREE_OPERAND (t, 1);
3503 if (TREE_CLOBBER_P (init))
3504 /* Just ignore clobbers. */
3507 /* First we figure out where we're storing to. */
3508 tree target = TREE_OPERAND (t, 0);
3510 maybe_simplify_trivial_copy (target, init);
3512 tree type = TREE_TYPE (target);
3513 target = cxx_eval_constant_expression (ctx, target,
3515 non_constant_p, overflow_p);
3516 if (*non_constant_p)
3519 /* cxx_eval_array_reference for lval = true allows references one past
3520 end of array, because it does not know if it is just taking address
3521 (which is valid), or actual dereference. Here we know it is
3522 a dereference, so diagnose it here. */
3523 for (tree probe = target; probe; )
3525 switch (TREE_CODE (probe))
3529 ary = TREE_OPERAND (probe, 0);
3530 nelts = get_array_or_vector_nelts (ctx, TREE_TYPE (ary),
3531 non_constant_p, overflow_p);
3532 VERIFY_CONSTANT (nelts);
3533 gcc_assert (TREE_CODE (nelts) == INTEGER_CST
3534 && TREE_CODE (TREE_OPERAND (probe, 1)) == INTEGER_CST);
3535 if (wi::to_widest (TREE_OPERAND (probe, 1)) == wi::to_widest (nelts))
3537 diag_array_subscript (ctx, ary, TREE_OPERAND (probe, 1));
3538 *non_constant_p = true;
3545 probe = TREE_OPERAND (probe, 0);
3554 if (!same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (target), type))
3556 /* For initialization of an empty base, the original target will be
3557 *(base*)this, which the above evaluation resolves to the object
3558 argument, which has the derived type rather than the base type. In
3559 this situation, just evaluate the initializer and return, since
3560 there's no actual data to store. */
3561 gcc_assert (is_empty_class (type));
3562 return cxx_eval_constant_expression (ctx, init, false,
3563 non_constant_p, overflow_p);
3566 /* And then find the underlying variable. */
3567 vec<tree,va_gc> *refs = make_tree_vector();
3568 tree object = NULL_TREE;
3569 for (tree probe = target; object == NULL_TREE; )
3571 switch (TREE_CODE (probe))
3576 vec_safe_push (refs, TREE_OPERAND (probe, 1));
3577 vec_safe_push (refs, TREE_TYPE (probe));
3578 probe = TREE_OPERAND (probe, 0);
3586 /* And then find/build up our initializer for the path to the subobject
3587 we're initializing. */
3589 if (object == ctx->object && VAR_P (object)
3590 && DECL_NAME (object) && ctx->call == NULL)
3591 /* The variable we're building up an aggregate initializer for is outside
3592 the constant-expression, so don't evaluate the store. We check
3593 DECL_NAME to handle TARGET_EXPR temporaries, which are fair game. */
3595 else if (DECL_P (object))
3596 valp = ctx->values->get (object);
3601 /* A constant-expression cannot modify objects from outside the
3602 constant-expression. */
3604 error ("modification of %qE is not a constant expression", object);
3605 *non_constant_p = true;
3608 type = TREE_TYPE (object);
3609 bool no_zero_init = true;
3611 vec<tree,va_gc> *ctors = make_tree_vector ();
3612 while (!refs->is_empty())
3614 if (*valp == NULL_TREE)
3616 *valp = build_constructor (type, NULL);
3617 CONSTRUCTOR_NO_IMPLICIT_ZERO (*valp) = no_zero_init;
3619 else if (TREE_CODE (*valp) == STRING_CST)
3621 /* An array was initialized with a string constant, and now
3622 we're writing into one of its elements. Explode the
3623 single initialization into a set of element
3625 gcc_assert (TREE_CODE (type) == ARRAY_TYPE);
3627 tree string = *valp;
3628 tree elt_type = TREE_TYPE (type);
3629 unsigned chars_per_elt = (TYPE_PRECISION (elt_type)
3630 / TYPE_PRECISION (char_type_node));
3631 unsigned num_elts = TREE_STRING_LENGTH (string) / chars_per_elt;
3632 tree ary_ctor = build_constructor (type, NULL);
3634 vec_safe_reserve (CONSTRUCTOR_ELTS (ary_ctor), num_elts);
3635 for (unsigned ix = 0; ix != num_elts; ix++)
3637 constructor_elt elt =
3639 build_int_cst (size_type_node, ix),
3640 extract_string_elt (string, chars_per_elt, ix)
3642 CONSTRUCTOR_ELTS (ary_ctor)->quick_push (elt);
3648 /* If the value of object is already zero-initialized, any new ctors for
3649 subobjects will also be zero-initialized. */
3650 no_zero_init = CONSTRUCTOR_NO_IMPLICIT_ZERO (*valp);
3652 vec_safe_push (ctors, *valp);
3654 enum tree_code code = TREE_CODE (type);
3656 tree index = refs->pop();
3658 constructor_elt *cep = NULL;
3659 if (code == ARRAY_TYPE)
3662 = find_array_ctor_elt (*valp, index, /*insert*/true);
3663 gcc_assert (i >= 0);
3664 cep = CONSTRUCTOR_ELT (*valp, i);
3665 gcc_assert (TREE_CODE (cep->index) != RANGE_EXPR);
3669 gcc_assert (TREE_CODE (index) == FIELD_DECL);
3671 /* We must keep the CONSTRUCTOR's ELTS in FIELD order.
3672 Usually we meet initializers in that order, but it is
3673 possible for base types to be placed not in program
3675 tree fields = TYPE_FIELDS (DECL_CONTEXT (index));
3676 unsigned HOST_WIDE_INT idx;
3678 if (code == UNION_TYPE && CONSTRUCTOR_NELTS (*valp)
3679 && CONSTRUCTOR_ELT (*valp, 0)->index != index)
3680 /* Changing active member. */
3681 vec_safe_truncate (CONSTRUCTOR_ELTS (*valp), 0);
3684 vec_safe_iterate (CONSTRUCTOR_ELTS (*valp), idx, &cep);
3685 idx++, fields = DECL_CHAIN (fields))
3687 if (index == cep->index)
3690 /* The field we're initializing must be on the field
3691 list. Look to see if it is present before the
3692 field the current ELT initializes. */
3693 for (; fields != cep->index; fields = DECL_CHAIN (fields))
3694 if (index == fields)
3698 /* We fell off the end of the CONSTRUCTOR, so insert a new
3699 entry at the end. */
3702 constructor_elt ce = { index, NULL_TREE };
3704 vec_safe_insert (CONSTRUCTOR_ELTS (*valp), idx, ce);
3705 cep = CONSTRUCTOR_ELT (*valp, idx);
3711 release_tree_vector (refs);
3713 if (AGGREGATE_TYPE_P (type) || VECTOR_TYPE_P (type))
3715 /* Create a new CONSTRUCTOR in case evaluation of the initializer
3716 wants to modify it. */
3717 if (*valp == NULL_TREE)
3719 *valp = build_constructor (type, NULL);
3720 CONSTRUCTOR_NO_IMPLICIT_ZERO (*valp) = no_zero_init;
3722 else if (TREE_CODE (*valp) == PTRMEM_CST)
3723 *valp = cplus_expand_constant (*valp);
3724 new_ctx.ctor = *valp;
3725 new_ctx.object = target;
3728 init = cxx_eval_constant_expression (&new_ctx, init, false,
3729 non_constant_p, overflow_p);
3730 /* Don't share a CONSTRUCTOR that might be changed later. */
3731 init = unshare_constructor (init);
3732 if (target == object)
3733 /* The hash table might have moved since the get earlier. */
3734 valp = ctx->values->get (object);
3736 if (TREE_CODE (init) == CONSTRUCTOR)
3738 /* An outer ctx->ctor might be pointing to *valp, so replace
3740 CONSTRUCTOR_ELTS (*valp) = CONSTRUCTOR_ELTS (init);
3741 TREE_CONSTANT (*valp) = TREE_CONSTANT (init);
3742 TREE_SIDE_EFFECTS (*valp) = TREE_SIDE_EFFECTS (init);
3743 CONSTRUCTOR_NO_IMPLICIT_ZERO (*valp)
3744 = CONSTRUCTOR_NO_IMPLICIT_ZERO (init);
3749 /* Update TREE_CONSTANT and TREE_SIDE_EFFECTS on enclosing
3750 CONSTRUCTORs, if any. */
3753 bool c = TREE_CONSTANT (init);
3754 bool s = TREE_SIDE_EFFECTS (init);
3756 FOR_EACH_VEC_SAFE_ELT (ctors, i, elt)
3759 TREE_CONSTANT (elt) = false;
3761 TREE_SIDE_EFFECTS (elt) = true;
3763 release_tree_vector (ctors);
3765 if (*non_constant_p)
3773 /* Evaluate a ++ or -- expression. */
3776 cxx_eval_increment_expression (const constexpr_ctx *ctx, tree t,
3778 bool *non_constant_p, bool *overflow_p)
3780 enum tree_code code = TREE_CODE (t);
3781 tree type = TREE_TYPE (t);
3782 tree op = TREE_OPERAND (t, 0);
3783 tree offset = TREE_OPERAND (t, 1);
3784 gcc_assert (TREE_CONSTANT (offset));
3786 /* The operand as an lvalue. */
3787 op = cxx_eval_constant_expression (ctx, op, true,
3788 non_constant_p, overflow_p);
3790 /* The operand as an rvalue. */
3792 = cxx_eval_constant_expression (ctx, op, false,
3793 non_constant_p, overflow_p);
3794 /* Don't VERIFY_CONSTANT if this might be dealing with a pointer to
3795 a local array in a constexpr function. */
3796 bool ptr = POINTER_TYPE_P (TREE_TYPE (val));
3798 VERIFY_CONSTANT (val);
3800 /* The modified value. */
3801 bool inc = (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR);
3803 if (POINTER_TYPE_P (type))
3805 /* The middle end requires pointers to use POINTER_PLUS_EXPR. */
3806 offset = convert_to_ptrofftype (offset);
3808 offset = fold_build1 (NEGATE_EXPR, TREE_TYPE (offset), offset);
3809 mod = fold_build2 (POINTER_PLUS_EXPR, type, val, offset);
3812 mod = fold_build2 (inc ? PLUS_EXPR : MINUS_EXPR, type, val, offset);
3814 VERIFY_CONSTANT (mod);
3816 /* Storing the modified value. */
3817 tree store = build2 (MODIFY_EXPR, type, op, mod);
3818 cxx_eval_constant_expression (ctx, store,
3819 true, non_constant_p, overflow_p);
3821 /* And the value of the expression. */
3822 if (code == PREINCREMENT_EXPR || code == PREDECREMENT_EXPR)
3824 /* Prefix ops are lvalues. */
3828 /* But we optimize when the caller wants an rvalue. */
3832 /* Postfix ops are rvalues. */
3836 /* Predicates for the meaning of *jump_target. */
3839 returns (tree *jump_target)
3842 && (TREE_CODE (*jump_target) == RETURN_EXPR
3843 || (TREE_CODE (*jump_target) == LABEL_DECL
3844 && LABEL_DECL_CDTOR (*jump_target)));
3848 breaks (tree *jump_target)
3851 && ((TREE_CODE (*jump_target) == LABEL_DECL
3852 && LABEL_DECL_BREAK (*jump_target))
3853 || TREE_CODE (*jump_target) == EXIT_EXPR);
3857 continues (tree *jump_target)
3860 && TREE_CODE (*jump_target) == LABEL_DECL
3861 && LABEL_DECL_CONTINUE (*jump_target);
3865 switches (tree *jump_target)
3868 && TREE_CODE (*jump_target) == INTEGER_CST;
3871 /* Subroutine of cxx_eval_statement_list. Determine whether the statement
3872 STMT matches *jump_target. If we're looking for a case label and we see
3873 the default label, note it in ctx->css_state. */
3876 label_matches (const constexpr_ctx *ctx, tree *jump_target, tree stmt)
3878 switch (TREE_CODE (*jump_target))
3881 if (TREE_CODE (stmt) == LABEL_EXPR
3882 && LABEL_EXPR_LABEL (stmt) == *jump_target)
3887 if (TREE_CODE (stmt) == CASE_LABEL_EXPR)
3889 gcc_assert (ctx->css_state != NULL);
3890 if (!CASE_LOW (stmt))
3892 /* default: should appear just once in a SWITCH_EXPR
3893 body (excluding nested SWITCH_EXPR). */
3894 gcc_assert (*ctx->css_state != css_default_seen);
3895 /* When evaluating SWITCH_EXPR body for the second time,
3896 return true for the default: label. */
3897 if (*ctx->css_state == css_default_processing)
3899 *ctx->css_state = css_default_seen;
3901 else if (CASE_HIGH (stmt))
3903 if (tree_int_cst_le (CASE_LOW (stmt), *jump_target)
3904 && tree_int_cst_le (*jump_target, CASE_HIGH (stmt)))
3907 else if (tree_int_cst_equal (*jump_target, CASE_LOW (stmt)))
3918 /* Evaluate a STATEMENT_LIST for side-effects. Handles various jump
3919 semantics, for switch, break, continue, and return. */
3922 cxx_eval_statement_list (const constexpr_ctx *ctx, tree t,
3923 bool *non_constant_p, bool *overflow_p,
3926 tree_stmt_iterator i;
3928 /* In a statement-expression we want to return the last value.
3929 For empty statement expression return void_node. */
3933 local_target = NULL_TREE;
3934 jump_target = &local_target;
3936 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
3938 tree stmt = tsi_stmt (i);
3939 /* We've found a continue, so skip everything until we reach
3940 the label its jumping to. */
3941 if (continues (jump_target))
3943 if (label_matches (ctx, jump_target, stmt))
3945 *jump_target = NULL_TREE;
3949 if (TREE_CODE (stmt) == DEBUG_BEGIN_STMT)
3951 r = cxx_eval_constant_expression (ctx, stmt, false,
3952 non_constant_p, overflow_p,
3954 if (*non_constant_p)
3956 if (returns (jump_target) || breaks (jump_target))
3962 /* Evaluate a LOOP_EXPR for side-effects. Handles break and return
3963 semantics; continue semantics are covered by cxx_eval_statement_list. */
3966 cxx_eval_loop_expr (const constexpr_ctx *ctx, tree t,
3967 bool *non_constant_p, bool *overflow_p,
3970 constexpr_ctx new_ctx = *ctx;
3972 tree body = TREE_OPERAND (t, 0);
3976 hash_set<tree> save_exprs;
3977 new_ctx.save_exprs = &save_exprs;
3979 cxx_eval_constant_expression (&new_ctx, body, /*lval*/false,
3980 non_constant_p, overflow_p, jump_target);
3982 /* Forget saved values of SAVE_EXPRs. */
3983 for (hash_set<tree>::iterator iter = save_exprs.begin();
3984 iter != save_exprs.end(); ++iter)
3985 new_ctx.values->remove (*iter);
3986 if (++count >= constexpr_loop_limit)
3989 error_at (EXPR_LOC_OR_LOC (t, input_location),
3990 "%<constexpr%> loop iteration count exceeds limit of %d "
3991 "(use -fconstexpr-loop-limit= to increase the limit)",
3992 constexpr_loop_limit);
3993 *non_constant_p = true;
3997 while (!returns (jump_target)
3998 && !breaks (jump_target)
3999 && !switches (jump_target)
4000 && !*non_constant_p);
4002 if (breaks (jump_target))
4003 *jump_target = NULL_TREE;
4008 /* Evaluate a SWITCH_EXPR for side-effects. Handles switch and break jump
4012 cxx_eval_switch_expr (const constexpr_ctx *ctx, tree t,
4013 bool *non_constant_p, bool *overflow_p,
4016 tree cond = SWITCH_COND (t);
4017 cond = cxx_eval_constant_expression (ctx, cond, false,
4018 non_constant_p, overflow_p);
4019 VERIFY_CONSTANT (cond);
4020 *jump_target = cond;
4022 tree body = SWITCH_BODY (t);
4023 constexpr_ctx new_ctx = *ctx;
4024 constexpr_switch_state css = css_default_not_seen;
4025 new_ctx.css_state = &css;
4026 cxx_eval_constant_expression (&new_ctx, body, false,
4027 non_constant_p, overflow_p, jump_target);
4028 if (switches (jump_target) && css == css_default_seen)
4030 /* If the SWITCH_EXPR body has default: label, process it once again,
4031 this time instructing label_matches to return true for default:
4032 label on switches (jump_target). */
4033 css = css_default_processing;
4034 cxx_eval_constant_expression (&new_ctx, body, false,
4035 non_constant_p, overflow_p, jump_target);
4037 if (breaks (jump_target) || switches (jump_target))
4038 *jump_target = NULL_TREE;
4042 /* Find the object of TYPE under initialization in CTX. */
4045 lookup_placeholder (const constexpr_ctx *ctx, bool lval, tree type)
4050 /* We could use ctx->object unconditionally, but using ctx->ctor when we
4051 can is a minor optimization. */
4052 if (!lval && ctx->ctor && same_type_p (TREE_TYPE (ctx->ctor), type))
4058 /* Since an object cannot have a field of its own type, we can search outward
4059 from ctx->object to find the unique containing object of TYPE. */
4060 tree ob = ctx->object;
4063 if (same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (ob), type))
4065 if (handled_component_p (ob))
4066 ob = TREE_OPERAND (ob, 0);
4074 /* Attempt to reduce the expression T to a constant value.
4075 On failure, issue diagnostic and return error_mark_node. */
4076 /* FIXME unify with c_fully_fold */
4077 /* FIXME overflow_p is too global */
4080 cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
4082 bool *non_constant_p, bool *overflow_p,
4085 constexpr_ctx new_ctx;
4088 if (jump_target && *jump_target)
4090 /* If we are jumping, ignore all statements/expressions except those
4091 that could have LABEL_EXPR or CASE_LABEL_EXPR in their bodies. */
4092 switch (TREE_CODE (t))
4095 case STATEMENT_LIST:
4100 case CASE_LABEL_EXPR:
4101 if (label_matches (ctx, jump_target, t))
4103 *jump_target = NULL_TREE;
4109 if (t == error_mark_node)
4111 *non_constant_p = true;
4114 if (CONSTANT_CLASS_P (t))
4116 if (TREE_OVERFLOW (t))
4119 permerror (input_location, "overflow in constant expression");
4120 if (!flag_permissive || ctx->quiet)
4124 if (TREE_CODE (t) == INTEGER_CST
4125 && TREE_CODE (TREE_TYPE (t)) == POINTER_TYPE
4126 && !integer_zerop (t))
4129 error ("value %qE of type %qT is not a constant expression",
4131 *non_constant_p = true;
4137 tree_code tcode = TREE_CODE (t);
4143 /* We ask for an rvalue for the RESULT_DECL when indirecting
4144 through an invisible reference, or in named return value
4146 if (tree *p = ctx->values->get (t))
4151 error ("%qE is not a constant expression", t);
4152 *non_constant_p = true;
4157 if (DECL_HAS_VALUE_EXPR_P (t))
4158 return cxx_eval_constant_expression (ctx, DECL_VALUE_EXPR (t),
4159 lval, non_constant_p, overflow_p);
4162 /* We used to not check lval for CONST_DECL, but darwin.c uses
4163 CONST_DECL for aggregate constants. */
4166 if (COMPLETE_TYPE_P (TREE_TYPE (t))
4167 && is_really_empty_class (TREE_TYPE (t)))
4169 /* If the class is empty, we aren't actually loading anything. */
4170 r = build_constructor (TREE_TYPE (t), NULL);
4171 TREE_CONSTANT (r) = true;
4173 else if (ctx->strict)
4174 r = decl_really_constant_value (t);
4176 r = decl_constant_value (t);
4177 if (TREE_CODE (r) == TARGET_EXPR
4178 && TREE_CODE (TARGET_EXPR_INITIAL (r)) == CONSTRUCTOR)
4179 r = TARGET_EXPR_INITIAL (r);
4181 if (tree *p = ctx->values->get (r))
4182 if (*p != NULL_TREE)
4187 non_const_var_error (r);
4188 *non_constant_p = true;
4192 case DEBUG_BEGIN_STMT:
4193 /* ??? It might be nice to retain this information somehow, so
4194 as to be able to step into a constexpr function call. */
4201 case CASE_LABEL_EXPR:
4206 if (lval && TREE_CODE (TREE_TYPE (t)) != REFERENCE_TYPE)
4208 else if (tree *p = ctx->values->get (r))
4211 /* Defer in case this is only used for its type. */;
4212 else if (TREE_CODE (TREE_TYPE (t)) == REFERENCE_TYPE)
4213 /* Defer, there's no lvalue->rvalue conversion. */;
4214 else if (COMPLETE_TYPE_P (TREE_TYPE (t))
4215 && is_really_empty_class (TREE_TYPE (t)))
4217 /* If the class is empty, we aren't actually loading anything. */
4218 r = build_constructor (TREE_TYPE (t), NULL);
4219 TREE_CONSTANT (r) = true;
4224 error ("%qE is not a constant expression", t);
4225 *non_constant_p = true;
4230 case AGGR_INIT_EXPR:
4231 r = cxx_eval_call_expression (ctx, t, lval,
4232 non_constant_p, overflow_p);
4237 r = DECL_EXPR_DECL (t);
4238 if (AGGREGATE_TYPE_P (TREE_TYPE (r))
4239 || VECTOR_TYPE_P (TREE_TYPE (r)))
4243 new_ctx.ctor = build_constructor (TREE_TYPE (r), NULL);
4244 CONSTRUCTOR_NO_IMPLICIT_ZERO (new_ctx.ctor) = true;
4245 new_ctx.values->put (r, new_ctx.ctor);
4249 if (tree init = DECL_INITIAL (r))
4251 init = cxx_eval_constant_expression (ctx, init,
4253 non_constant_p, overflow_p);
4254 /* Don't share a CONSTRUCTOR that might be changed. */
4255 init = unshare_constructor (init);
4256 ctx->values->put (r, init);
4258 else if (ctx == &new_ctx)
4259 /* We gave it a CONSTRUCTOR above. */;
4261 ctx->values->put (r, NULL_TREE);
4266 if (!literal_type_p (TREE_TYPE (t)))
4270 error ("temporary of non-literal type %qT in a "
4271 "constant expression", TREE_TYPE (t));
4272 explain_non_literal_class (TREE_TYPE (t));
4274 *non_constant_p = true;
4277 if ((AGGREGATE_TYPE_P (TREE_TYPE (t)) || VECTOR_TYPE_P (TREE_TYPE (t))))
4279 /* We're being expanded without an explicit target, so start
4280 initializing a new object; expansion with an explicit target
4281 strips the TARGET_EXPR before we get here. */
4283 new_ctx.ctor = build_constructor (TREE_TYPE (t), NULL);
4284 CONSTRUCTOR_NO_IMPLICIT_ZERO (new_ctx.ctor) = true;
4285 new_ctx.object = TARGET_EXPR_SLOT (t);
4286 ctx->values->put (new_ctx.object, new_ctx.ctor);
4289 /* Pass false for 'lval' because this indicates
4290 initialization of a temporary. */
4291 r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 1),
4293 non_constant_p, overflow_p);
4294 if (!*non_constant_p)
4295 /* Adjust the type of the result to the type of the temporary. */
4296 r = adjust_temp_type (TREE_TYPE (t), r);
4299 tree slot = TARGET_EXPR_SLOT (t);
4300 r = unshare_constructor (r);
4301 ctx->values->put (slot, r);
4308 gcc_assert (jump_target == NULL || *jump_target == NULL_TREE);
4309 r = cxx_eval_store_expression (ctx, t, lval,
4310 non_constant_p, overflow_p);
4314 r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 1),
4316 non_constant_p, overflow_p);
4320 if (TREE_OPERAND (t, 0) != NULL_TREE)
4321 r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0),
4323 non_constant_p, overflow_p);
4328 /* Can happen with ({ return true; }) && false; passed to
4329 maybe_constant_value. There is nothing to jump over in this
4330 case, and the bug will be diagnosed later. */
4331 gcc_assert (ctx->quiet);
4332 *non_constant_p = true;
4337 /* Avoid evaluating a SAVE_EXPR more than once. */
4338 if (tree *p = ctx->values->get (t))
4342 r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0), false,
4343 non_constant_p, overflow_p);
4344 ctx->values->put (t, r);
4345 if (ctx->save_exprs)
4346 ctx->save_exprs->add (t);
4350 case NON_LVALUE_EXPR:
4351 case TRY_CATCH_EXPR:
4353 case CLEANUP_POINT_EXPR:
4354 case MUST_NOT_THROW_EXPR:
4357 r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0),
4359 non_constant_p, overflow_p,
4363 case TRY_FINALLY_EXPR:
4364 r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0), lval,
4365 non_constant_p, overflow_p,
4367 if (!*non_constant_p)
4368 /* Also evaluate the cleanup. */
4369 cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 1), true,
4370 non_constant_p, overflow_p,
4374 /* These differ from cxx_eval_unary_expression in that this doesn't
4375 check for a constant operand or result; an address can be
4376 constant without its operand being, and vice versa. */
4379 r = cxx_eval_indirect_ref (ctx, t, lval,
4380 non_constant_p, overflow_p);
4385 tree oldop = TREE_OPERAND (t, 0);
4386 tree op = cxx_eval_constant_expression (ctx, oldop,
4388 non_constant_p, overflow_p);
4389 /* Don't VERIFY_CONSTANT here. */
4390 if (*non_constant_p)
4392 gcc_checking_assert (TREE_CODE (op) != CONSTRUCTOR);
4393 /* This function does more aggressive folding than fold itself. */
4394 r = build_fold_addr_expr_with_type (op, TREE_TYPE (t));
4395 if (TREE_CODE (r) == ADDR_EXPR && TREE_OPERAND (r, 0) == oldop)
4404 r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0), lval,
4405 non_constant_p, overflow_p);
4406 if (r == error_mark_node)
4408 else if (r == TREE_OPERAND (t, 0))
4411 r = fold_build1 (TREE_CODE (t), TREE_TYPE (t), r);
4416 case FIX_TRUNC_EXPR:
4421 case TRUTH_NOT_EXPR:
4422 case FIXED_CONVERT_EXPR:
4423 r = cxx_eval_unary_expression (ctx, t, lval,
4424 non_constant_p, overflow_p);
4428 r = fold_sizeof_expr (t);
4429 VERIFY_CONSTANT (r);
4434 /* check_return_expr sometimes wraps a TARGET_EXPR in a
4435 COMPOUND_EXPR; don't get confused. Also handle EMPTY_CLASS_EXPR
4436 introduced by build_call_a. */
4437 tree op0 = TREE_OPERAND (t, 0);
4438 tree op1 = TREE_OPERAND (t, 1);
4440 if ((TREE_CODE (op0) == TARGET_EXPR && op1 == TARGET_EXPR_SLOT (op0))
4441 || TREE_CODE (op1) == EMPTY_CLASS_EXPR)
4442 r = cxx_eval_constant_expression (ctx, op0,
4443 lval, non_constant_p, overflow_p,
4447 /* Check that the LHS is constant and then discard it. */
4448 cxx_eval_constant_expression (ctx, op0,
4449 true, non_constant_p, overflow_p,
4451 if (*non_constant_p)
4453 op1 = TREE_OPERAND (t, 1);
4454 r = cxx_eval_constant_expression (ctx, op1,
4455 lval, non_constant_p, overflow_p,
4461 case POINTER_PLUS_EXPR:
4462 case POINTER_DIFF_EXPR:
4466 case TRUNC_DIV_EXPR:
4468 case FLOOR_DIV_EXPR:
4469 case ROUND_DIV_EXPR:
4470 case TRUNC_MOD_EXPR:
4472 case ROUND_MOD_EXPR:
4474 case EXACT_DIV_EXPR:
4484 case TRUTH_XOR_EXPR:
4491 case UNORDERED_EXPR:
4501 r = cxx_eval_binary_expression (ctx, t, lval,
4502 non_constant_p, overflow_p);
4505 /* fold can introduce non-IF versions of these; still treat them as
4506 short-circuiting. */
4507 case TRUTH_AND_EXPR:
4508 case TRUTH_ANDIF_EXPR:
4509 r = cxx_eval_logical_expression (ctx, t, boolean_false_node,
4512 non_constant_p, overflow_p);
4516 case TRUTH_ORIF_EXPR:
4517 r = cxx_eval_logical_expression (ctx, t, boolean_true_node,
4520 non_constant_p, overflow_p);
4524 r = cxx_eval_array_reference (ctx, t, lval,
4525 non_constant_p, overflow_p);
4529 if (is_overloaded_fn (t))
4531 /* We can only get here in checking mode via
4532 build_non_dependent_expr, because any expression that
4533 calls or takes the address of the function will have
4534 pulled a FUNCTION_DECL out of the COMPONENT_REF. */
4535 gcc_checking_assert (ctx->quiet || errorcount);
4536 *non_constant_p = true;
4539 r = cxx_eval_component_reference (ctx, t, lval,
4540 non_constant_p, overflow_p);
4544 r = cxx_eval_bit_field_ref (ctx, t, lval,
4545 non_constant_p, overflow_p);
4549 if (jump_target && *jump_target)
4551 tree orig_jump = *jump_target;
4552 /* When jumping to a label, the label might be either in the
4553 then or else blocks, so process then block first in skipping
4554 mode first, and if we are still in the skipping mode at its end,
4555 process the else block too. */
4556 r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 1),
4557 lval, non_constant_p, overflow_p,
4559 /* It's possible that we found the label in the then block. But
4560 it could have been followed by another jumping statement, e.g.
4561 say we're looking for case 1:
4564 // skipped statements
4565 case 1:; // clears up *jump_target
4566 return 1; // and sets it to a RETURN_EXPR
4569 in which case we need not go looking to the else block.
4570 (goto is not allowed in a constexpr function.) */
4571 if (*jump_target == orig_jump)
4572 r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 2),
4573 lval, non_constant_p, overflow_p,
4577 r = cxx_eval_conditional_expression (ctx, t, lval,
4578 non_constant_p, overflow_p,
4582 r = cxx_eval_vector_conditional_expression (ctx, t, non_constant_p,
4587 if (TREE_CONSTANT (t) && reduced_constant_expression_p (t))
4589 /* Don't re-process a constant CONSTRUCTOR, but do fold it to
4590 VECTOR_CST if applicable. */
4591 verify_constructor_flags (t);
4592 if (TREE_CONSTANT (t))
4595 r = cxx_eval_bare_aggregate (ctx, t, lval,
4596 non_constant_p, overflow_p);
4600 /* We can get this in a defaulted constructor for a class with a
4601 non-static data member of array type. Either the initializer will
4602 be NULL, meaning default-initialization, or it will be an lvalue
4603 or xvalue of the same type, meaning direct-initialization from the
4604 corresponding member. */
4605 r = cxx_eval_vec_init (ctx, t, lval,
4606 non_constant_p, overflow_p);
4611 r = cxx_eval_trinary_expression (ctx, t, lval,
4612 non_constant_p, overflow_p);
4616 if (REINTERPRET_CAST_P (t))
4619 error_at (EXPR_LOC_OR_LOC (t, input_location),
4620 "a reinterpret_cast is not a constant expression");
4621 *non_constant_p = true;
4626 case VIEW_CONVERT_EXPR:
4627 case UNARY_PLUS_EXPR:
4629 tree oldop = TREE_OPERAND (t, 0);
4631 tree op = cxx_eval_constant_expression (ctx, oldop,
4633 non_constant_p, overflow_p);
4634 if (*non_constant_p)
4636 tree type = TREE_TYPE (t);
4637 if (TREE_CODE (op) == PTRMEM_CST
4638 && !TYPE_PTRMEM_P (type))
4639 op = cplus_expand_constant (op);
4641 if (TREE_CODE (op) == PTRMEM_CST && tcode == NOP_EXPR)
4643 if (!same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (op))
4644 && !can_convert_qual (type, op))
4645 op = cplus_expand_constant (op);
4646 return cp_fold_convert (type, op);
4649 if (POINTER_TYPE_P (type) && TREE_CODE (op) == INTEGER_CST)
4651 if (integer_zerop (op))
4653 if (TREE_CODE (type) == REFERENCE_TYPE)
4656 error_at (EXPR_LOC_OR_LOC (t, input_location),
4657 "dereferencing a null pointer");
4658 *non_constant_p = true;
4661 else if (TREE_CODE (TREE_TYPE (op)) == POINTER_TYPE)
4663 tree from = TREE_TYPE (op);
4665 if (!can_convert (type, from, tf_none))
4668 error_at (EXPR_LOC_OR_LOC (t, input_location),
4669 "conversion of %qT null pointer to %qT "
4670 "is not a constant expression",
4672 *non_constant_p = true;
4679 /* This detects for example:
4680 reinterpret_cast<void*>(sizeof 0)
4683 error_at (EXPR_LOC_OR_LOC (t, input_location),
4684 "%<reinterpret_cast<%T>(%E)%> is not "
4685 "a constant expression",
4687 *non_constant_p = true;
4692 if (op == oldop && tcode != UNARY_PLUS_EXPR)
4693 /* We didn't fold at the top so we could check for ptr-int
4697 if (tcode == UNARY_PLUS_EXPR)
4698 r = fold_convert (TREE_TYPE (t), op);
4700 r = fold_build1 (tcode, type, op);
4702 /* Conversion of an out-of-range value has implementation-defined
4703 behavior; the language considers it different from arithmetic
4704 overflow, which is undefined. */
4705 if (TREE_OVERFLOW_P (r) && !TREE_OVERFLOW_P (op))
4706 TREE_OVERFLOW (r) = false;
4710 case EMPTY_CLASS_EXPR:
4711 /* This is good enough for a function argument that might not get
4712 used, and they can't do anything with it, so just return it. */
4715 case STATEMENT_LIST:
4717 new_ctx.ctor = new_ctx.object = NULL_TREE;
4718 return cxx_eval_statement_list (&new_ctx, t,
4719 non_constant_p, overflow_p, jump_target);
4722 return cxx_eval_constant_expression (ctx, BIND_EXPR_BODY (t),
4724 non_constant_p, overflow_p,
4727 case PREINCREMENT_EXPR:
4728 case POSTINCREMENT_EXPR:
4729 case PREDECREMENT_EXPR:
4730 case POSTDECREMENT_EXPR:
4731 return cxx_eval_increment_expression (ctx, t,
4732 lval, non_constant_p, overflow_p);
4738 case VEC_DELETE_EXPR:
4741 /* GCC internal stuff. */
4744 case NON_DEPENDENT_EXPR:
4748 error_at (EXPR_LOC_OR_LOC (t, input_location),
4749 "expression %qE is not a constant expression", t);
4750 *non_constant_p = true;
4753 case PLACEHOLDER_EXPR:
4754 /* Use of the value or address of the current object. */
4755 if (tree ctor = lookup_placeholder (ctx, lval, TREE_TYPE (t)))
4756 return cxx_eval_constant_expression (ctx, ctor, lval,
4757 non_constant_p, overflow_p);
4758 /* A placeholder without a referent. We can get here when
4759 checking whether NSDMIs are noexcept, or in massage_init_elt;
4760 just say it's non-constant for now. */
4761 gcc_assert (ctx->quiet);
4762 *non_constant_p = true;
4767 tree cond = TREE_OPERAND (t, 0);
4768 cond = cxx_eval_constant_expression (ctx, cond, /*lval*/false,
4769 non_constant_p, overflow_p);
4770 VERIFY_CONSTANT (cond);
4771 if (integer_nonzerop (cond))
4777 *jump_target = TREE_OPERAND (t, 0);
4778 gcc_assert (breaks (jump_target) || continues (jump_target)
4779 /* Allow for jumping to a cdtor_label. */
4780 || returns (jump_target));
4784 cxx_eval_loop_expr (ctx, t,
4785 non_constant_p, overflow_p, jump_target);
4789 cxx_eval_switch_expr (ctx, t,
4790 non_constant_p, overflow_p, jump_target);
4794 /* It's possible to get a requires-expression in a constant
4795 expression. For example:
4797 template<typename T> concept bool C() {
4798 return requires (T t) { t; };
4801 template<typename T> requires !C<T>() void f(T);
4803 Normalization leaves f with the associated constraint
4804 '!requires (T t) { ... }' which is not transformed into
4806 if (!processing_template_decl)
4807 return evaluate_constraint_expression (t, NULL_TREE);
4809 *non_constant_p = true;
4813 r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0),
4815 non_constant_p, overflow_p,
4824 if (STATEMENT_CODE_P (TREE_CODE (t)))
4826 /* This function doesn't know how to deal with pre-genericize
4827 statements; this can only happen with statement-expressions,
4828 so for now just fail. */
4830 error_at (EXPR_LOCATION (t),
4831 "statement is not a constant expression");
4834 internal_error ("unexpected expression %qE of kind %s", t,
4835 get_tree_code_name (TREE_CODE (t)));
4836 *non_constant_p = true;
4840 if (r == error_mark_node)
4841 *non_constant_p = true;
4843 if (*non_constant_p)
4850 cxx_eval_outermost_constant_expr (tree t, bool allow_non_constant,
4851 bool strict = true, tree object = NULL_TREE)
4853 auto_timevar time (TV_CONSTEXPR);
4855 bool non_constant_p = false;
4856 bool overflow_p = false;
4857 hash_map<tree,tree> map;
4859 constexpr_ctx ctx = { NULL, &map, NULL, NULL, NULL, NULL,
4860 allow_non_constant, strict };
4862 tree type = initialized_type (t);
4864 if (AGGREGATE_TYPE_P (type) || VECTOR_TYPE_P (type))
4866 /* In C++14 an NSDMI can participate in aggregate initialization,
4867 and can refer to the address of the object being initialized, so
4868 we need to pass in the relevant VAR_DECL if we want to do the
4869 evaluation in a single pass. The evaluation will dynamically
4870 update ctx.values for the VAR_DECL. We use the same strategy
4871 for C++11 constexpr constructors that refer to the object being
4873 ctx.ctor = build_constructor (type, NULL);
4874 CONSTRUCTOR_NO_IMPLICIT_ZERO (ctx.ctor) = true;
4877 if (TREE_CODE (t) == TARGET_EXPR)
4878 object = TARGET_EXPR_SLOT (t);
4879 else if (TREE_CODE (t) == AGGR_INIT_EXPR)
4880 object = AGGR_INIT_EXPR_SLOT (t);
4882 ctx.object = object;
4884 gcc_assert (same_type_ignoring_top_level_qualifiers_p
4885 (type, TREE_TYPE (object)));
4886 if (object && DECL_P (object))
4887 map.put (object, ctx.ctor);
4888 if (TREE_CODE (r) == TARGET_EXPR)
4889 /* Avoid creating another CONSTRUCTOR when we expand the
4891 r = TARGET_EXPR_INITIAL (r);
4894 r = cxx_eval_constant_expression (&ctx, r,
4895 false, &non_constant_p, &overflow_p);
4897 verify_constant (r, allow_non_constant, &non_constant_p, &overflow_p);
4899 /* Mutable logic is a bit tricky: we want to allow initialization of
4900 constexpr variables with mutable members, but we can't copy those
4901 members to another constexpr variable. */
4902 if (TREE_CODE (r) == CONSTRUCTOR
4903 && CONSTRUCTOR_MUTABLE_POISON (r))
4905 if (!allow_non_constant)
4906 error ("%qE is not a constant expression because it refers to "
4907 "mutable subobjects of %qT", t, type);
4908 non_constant_p = true;
4911 if (TREE_CODE (r) == CONSTRUCTOR
4912 && CONSTRUCTOR_NO_IMPLICIT_ZERO (r))
4914 if (!allow_non_constant)
4915 error ("%qE is not a constant expression because it refers to "
4916 "an incompletely initialized variable", t);
4917 TREE_CONSTANT (r) = false;
4918 non_constant_p = true;
4921 /* Technically we should check this for all subexpressions, but that
4922 runs into problems with our internal representation of pointer
4923 subtraction and the 5.19 rules are still in flux. */
4924 if (CONVERT_EXPR_CODE_P (TREE_CODE (r))
4925 && ARITHMETIC_TYPE_P (TREE_TYPE (r))
4926 && TREE_CODE (TREE_OPERAND (r, 0)) == ADDR_EXPR)
4928 if (!allow_non_constant)
4929 error ("conversion from pointer type %qT "
4930 "to arithmetic type %qT in a constant expression",
4931 TREE_TYPE (TREE_OPERAND (r, 0)), TREE_TYPE (r));
4932 non_constant_p = true;
4935 if (!non_constant_p && overflow_p)
4936 non_constant_p = true;
4938 /* Unshare the result unless it's a CONSTRUCTOR in which case it's already
4940 bool should_unshare = true;
4941 if (r == t || TREE_CODE (r) == CONSTRUCTOR)
4942 should_unshare = false;
4944 if (non_constant_p && !allow_non_constant)
4945 return error_mark_node;
4946 else if (non_constant_p && TREE_CONSTANT (r))
4948 /* This isn't actually constant, so unset TREE_CONSTANT.
4949 Don't clear TREE_CONSTANT on ADDR_EXPR, as the middle-end requires
4950 it to be set if it is invariant address, even when it is not
4951 a valid C++ constant expression. Wrap it with a NOP_EXPR
4953 if (EXPR_P (r) && TREE_CODE (r) != ADDR_EXPR)
4955 else if (TREE_CODE (r) == CONSTRUCTOR)
4956 r = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (r), r);
4958 r = build_nop (TREE_TYPE (r), r);
4959 TREE_CONSTANT (r) = false;
4961 else if (non_constant_p || r == t)
4965 r = unshare_expr (r);
4967 if (TREE_CODE (r) == CONSTRUCTOR && CLASS_TYPE_P (TREE_TYPE (r)))
4969 if (TREE_CODE (t) == TARGET_EXPR
4970 && TARGET_EXPR_INITIAL (t) == r)
4974 r = get_target_expr (r);
4975 TREE_CONSTANT (r) = true;
4983 /* Returns true if T is a valid subexpression of a constant expression,
4984 even if it isn't itself a constant expression. */
4987 is_sub_constant_expr (tree t)
4989 bool non_constant_p = false;
4990 bool overflow_p = false;
4991 hash_map <tree, tree> map;
4993 constexpr_ctx ctx = { NULL, &map, NULL, NULL, NULL, NULL, true, true };
4995 cxx_eval_constant_expression (&ctx, t, false, &non_constant_p,
4997 return !non_constant_p && !overflow_p;
5000 /* If T represents a constant expression returns its reduced value.
5001 Otherwise return error_mark_node. If T is dependent, then
5005 cxx_constant_value (tree t, tree decl)
5007 return cxx_eval_outermost_constant_expr (t, false, true, decl);
5010 /* Helper routine for fold_simple function. Either return simplified
5011 expression T, otherwise NULL_TREE.
5012 In contrast to cp_fully_fold, and to maybe_constant_value, we try to fold
5013 even if we are within template-declaration. So be careful on call, as in
5014 such case types can be undefined. */
5017 fold_simple_1 (tree t)
5020 enum tree_code code = TREE_CODE (t);
5032 return fold_sizeof_expr (t);
5040 case TRUTH_NOT_EXPR:
5042 case VIEW_CONVERT_EXPR:
5045 case FIX_TRUNC_EXPR:
5046 case FIXED_CONVERT_EXPR:
5047 case ADDR_SPACE_CONVERT_EXPR:
5049 op1 = TREE_OPERAND (t, 0);
5051 t = const_unop (code, TREE_TYPE (t), op1);
5055 if (CONVERT_EXPR_CODE_P (code)
5056 && TREE_OVERFLOW_P (t) && !TREE_OVERFLOW_P (op1))
5057 TREE_OVERFLOW (t) = false;
5065 /* If T is a simple constant expression, returns its simplified value.
5066 Otherwise returns T. In contrast to maybe_constant_value we
5067 simplify only few operations on constant-expressions, and we don't
5068 try to simplify constexpressions. */
5071 fold_simple (tree t)
5073 if (processing_template_decl)
5076 tree r = fold_simple_1 (t);
5083 /* If T is a constant expression, returns its reduced value.
5084 Otherwise, if T does not have TREE_CONSTANT set, returns T.
5085 Otherwise, returns a version of T without TREE_CONSTANT. */
5087 static GTY((deletable)) hash_map<tree, tree> *cv_cache;
5090 maybe_constant_value (tree t, tree decl)
5094 if (!is_nondependent_constant_expression (t))
5096 if (TREE_OVERFLOW_P (t))
5098 t = build_nop (TREE_TYPE (t), t);
5099 TREE_CONSTANT (t) = false;
5103 else if (CONSTANT_CLASS_P (t))
5104 /* No caching or evaluation needed. */
5107 if (cv_cache == NULL)
5108 cv_cache = hash_map<tree, tree>::create_ggc (101);
5109 if (tree *cached = cv_cache->get (t))
5112 r = cxx_eval_outermost_constant_expr (t, true, true, decl);
5113 gcc_checking_assert (r == t
5114 || CONVERT_EXPR_P (t)
5115 || TREE_CODE (t) == VIEW_CONVERT_EXPR
5116 || (TREE_CONSTANT (t) && !TREE_CONSTANT (r))
5117 || !cp_tree_equal (r, t));
5118 cv_cache->put (t, r);
5122 /* Dispose of the whole CV_CACHE. */
5125 clear_cv_cache (void)
5127 if (cv_cache != NULL)
5131 /* Dispose of the whole CV_CACHE and FOLD_CACHE. */
5134 clear_cv_and_fold_caches (void)
5137 clear_fold_cache ();
5140 /* Like maybe_constant_value but first fully instantiate the argument.
5142 Note: this is equivalent to instantiate_non_dependent_expr_sfinae
5143 (t, complain) followed by maybe_constant_value but is more efficient,
5144 because calls instantiation_dependent_expression_p and
5145 potential_constant_expression at most once. */
5148 fold_non_dependent_expr (tree t, tsubst_flags_t complain /* = tf_none */)
5153 /* If we're in a template, but T isn't value dependent, simplify
5154 it. We're supposed to treat:
5156 template <typename T> void f(T[1 + 1]);
5157 template <typename T> void f(T[2]);
5159 as two declarations of the same function, for example. */
5160 if (processing_template_decl)
5162 if (is_nondependent_constant_expression (t))
5164 processing_template_decl_sentinel s;
5165 t = instantiate_non_dependent_expr_internal (t, complain);
5167 if (type_unknown_p (t)
5168 || BRACE_ENCLOSED_INITIALIZER_P (t))
5170 if (TREE_OVERFLOW_P (t))
5172 t = build_nop (TREE_TYPE (t), t);
5173 TREE_CONSTANT (t) = false;
5178 tree r = cxx_eval_outermost_constant_expr (t, true, true, NULL_TREE);
5179 /* cp_tree_equal looks through NOPs, so allow them. */
5180 gcc_checking_assert (r == t
5181 || CONVERT_EXPR_P (t)
5182 || TREE_CODE (t) == VIEW_CONVERT_EXPR
5183 || (TREE_CONSTANT (t) && !TREE_CONSTANT (r))
5184 || !cp_tree_equal (r, t));
5187 else if (TREE_OVERFLOW_P (t))
5189 t = build_nop (TREE_TYPE (t), t);
5190 TREE_CONSTANT (t) = false;
5195 return maybe_constant_value (t);
5198 /* Like maybe_constant_value, but returns a CONSTRUCTOR directly, rather
5199 than wrapped in a TARGET_EXPR. */
5202 maybe_constant_init_1 (tree t, tree decl, bool allow_non_constant)
5206 if (TREE_CODE (t) == EXPR_STMT)
5207 t = TREE_OPERAND (t, 0);
5208 if (TREE_CODE (t) == CONVERT_EXPR
5209 && VOID_TYPE_P (TREE_TYPE (t)))
5210 t = TREE_OPERAND (t, 0);
5211 if (TREE_CODE (t) == INIT_EXPR)
5212 t = TREE_OPERAND (t, 1);
5213 if (TREE_CODE (t) == TARGET_EXPR)
5214 t = TARGET_EXPR_INITIAL (t);
5215 if (!is_nondependent_static_init_expression (t))
5216 /* Don't try to evaluate it. */;
5217 else if (CONSTANT_CLASS_P (t) && allow_non_constant)
5218 /* No evaluation needed. */;
5220 t = cxx_eval_outermost_constant_expr (t, allow_non_constant, false, decl);
5221 if (TREE_CODE (t) == TARGET_EXPR)
5223 tree init = TARGET_EXPR_INITIAL (t);
5224 if (TREE_CODE (init) == CONSTRUCTOR)
5230 /* Wrapper for maybe_constant_init_1 which permits non constants. */
5233 maybe_constant_init (tree t, tree decl)
5235 return maybe_constant_init_1 (t, decl, true);
5238 /* Wrapper for maybe_constant_init_1 which does not permit non constants. */
5241 cxx_constant_init (tree t, tree decl)
5243 return maybe_constant_init_1 (t, decl, false);
5247 /* FIXME see ADDR_EXPR section in potential_constant_expression_1. */
5248 /* Return true if the object referred to by REF has automatic or thread
5251 enum { ck_ok, ck_bad, ck_unknown };
5253 check_automatic_or_tls (tree ref)
5256 poly_int64 bitsize, bitpos;
5258 int volatilep = 0, unsignedp = 0;
5259 tree decl = get_inner_reference (ref, &bitsize, &bitpos, &offset,
5260 &mode, &unsignedp, &volatilep, false);
5263 /* If there isn't a decl in the middle, we don't know the linkage here,
5264 and this isn't a constant expression anyway. */
5267 dk = decl_storage_duration (decl);
5268 return (dk == dk_auto || dk == dk_thread) ? ck_bad : ck_ok;
5272 /* Return true if T denotes a potentially constant expression. Issue
5273 diagnostic as appropriate under control of FLAGS. If WANT_RVAL is true,
5274 an lvalue-rvalue conversion is implied. If NOW is true, we want to
5275 consider the expression in the current context, independent of constexpr
5278 C++0x [expr.const] used to say
5280 6 An expression is a potential constant expression if it is
5281 a constant expression where all occurrences of function
5282 parameters are replaced by arbitrary constant expressions
5283 of the appropriate type.
5285 2 A conditional expression is a constant expression unless it
5286 involves one of the following as a potentially evaluated
5287 subexpression (3.2), but subexpressions of logical AND (5.14),
5288 logical OR (5.15), and conditional (5.16) operations that are
5289 not evaluated are not considered. */
5292 potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now,
5293 tsubst_flags_t flags)
5295 #define RECUR(T,RV) \
5296 potential_constant_expression_1 ((T), (RV), strict, now, flags)
5298 enum { any = false, rval = true };
5302 if (t == error_mark_node)
5306 location_t loc = EXPR_LOC_OR_LOC (t, input_location);
5307 if (TREE_THIS_VOLATILE (t) && !DECL_P (t))
5309 if (flags & tf_error)
5310 error_at (loc, "expression %qE has side-effects", t);
5313 if (CONSTANT_CLASS_P (t))
5315 if (CODE_CONTAINS_STRUCT (TREE_CODE (t), TS_TYPED)
5316 && TREE_TYPE (t) == error_mark_node)
5319 switch (TREE_CODE (t))
5325 case TEMPLATE_ID_EXPR:
5328 case CASE_LABEL_EXPR:
5334 case TEMPLATE_PARM_INDEX:
5336 case IDENTIFIER_NODE:
5337 case USERDEF_LITERAL:
5338 /* We can see a FIELD_DECL in a pointer-to-member expression. */
5343 case PLACEHOLDER_EXPR:
5348 case DEBUG_BEGIN_STMT:
5354 if (flags & tf_error)
5355 error ("%qE is not a constant expression", t);
5360 case AGGR_INIT_EXPR:
5362 /* -- an invocation of a function other than a constexpr function
5363 or a constexpr constructor. */
5365 tree fun = get_function_named_in_call (t);
5366 const int nargs = call_expr_nargs (t);
5369 if (fun == NULL_TREE)
5371 /* Reset to allow the function to continue past the end
5372 of the block below. Otherwise return early. */
5375 if (TREE_CODE (t) == CALL_EXPR
5376 && CALL_EXPR_FN (t) == NULL_TREE)
5377 switch (CALL_EXPR_IFN (t))
5379 /* These should be ignored, they are optimized away from
5380 constexpr functions. */
5381 case IFN_UBSAN_NULL:
5382 case IFN_UBSAN_BOUNDS:
5383 case IFN_UBSAN_VPTR:
5384 case IFN_FALLTHROUGH:
5387 case IFN_ADD_OVERFLOW:
5388 case IFN_SUB_OVERFLOW:
5389 case IFN_MUL_OVERFLOW:
5399 /* fold_call_expr can't do anything with IFN calls. */
5400 if (flags & tf_error)
5401 error_at (loc, "call to internal function %qE", t);
5406 if (fun && is_overloaded_fn (fun))
5408 if (TREE_CODE (fun) == FUNCTION_DECL)
5410 if (builtin_valid_in_constant_expr_p (fun))
5412 if (!DECL_DECLARED_CONSTEXPR_P (fun)
5413 /* Allow any built-in function; if the expansion
5414 isn't constant, we'll deal with that then. */
5415 && !is_builtin_fn (fun))
5417 if (flags & tf_error)
5419 error_at (loc, "call to non-%<constexpr%> function %qD",
5421 explain_invalid_constexpr_fn (fun);
5425 /* A call to a non-static member function takes the address
5426 of the object as the first argument. But in a constant
5427 expression the address will be folded away, so look
5429 if (DECL_NONSTATIC_MEMBER_FUNCTION_P (fun)
5430 && !DECL_CONSTRUCTOR_P (fun))
5432 tree x = get_nth_callarg (t, 0);
5433 if (is_this_parameter (x))
5435 /* Don't require an immediately constant value, as
5436 constexpr substitution might not use the value. */
5437 bool sub_now = false;
5438 if (!potential_constant_expression_1 (x, rval, strict,
5446 if (!RECUR (fun, true))
5448 fun = get_first_fn (fun);
5450 /* Skip initial arguments to base constructors. */
5451 if (DECL_BASE_CONSTRUCTOR_P (fun))
5452 i = num_artificial_parms_for (fun);
5453 fun = DECL_ORIGIN (fun);
5457 if (RECUR (fun, rval))
5458 /* Might end up being a constant function pointer. */;
5462 for (; i < nargs; ++i)
5464 tree x = get_nth_callarg (t, i);
5465 /* In a template, reference arguments haven't been converted to
5466 REFERENCE_TYPE and we might not even know if the parameter
5467 is a reference, so accept lvalue constants too. */
5468 bool rv = processing_template_decl ? any : rval;
5469 /* Don't require an immediately constant value, as constexpr
5470 substitution might not use the value of the argument. */
5471 bool sub_now = false;
5472 if (!potential_constant_expression_1 (x, rv, strict,
5479 case NON_LVALUE_EXPR:
5480 /* -- an lvalue-to-rvalue conversion (4.1) unless it is applied to
5481 -- an lvalue of integral type that refers to a non-volatile
5482 const variable or static data member initialized with
5483 constant expressions, or
5485 -- an lvalue of literal type that refers to non-volatile
5486 object defined with constexpr, or that refers to a
5487 sub-object of such an object; */
5488 return RECUR (TREE_OPERAND (t, 0), rval);
5491 if (DECL_HAS_VALUE_EXPR_P (t))
5493 if (now && is_normal_capture_proxy (t))
5495 /* -- in a lambda-expression, a reference to this or to a
5496 variable with automatic storage duration defined outside that
5497 lambda-expression, where the reference would be an
5499 if (flags & tf_error)
5501 tree cap = DECL_CAPTURED_VARIABLE (t);
5502 error ("lambda capture of %qE is not a constant expression",
5504 if (!want_rval && decl_constant_var_p (cap))
5505 inform (input_location, "because it is used as a glvalue");
5509 return RECUR (DECL_VALUE_EXPR (t), rval);
5512 && !var_in_maybe_constexpr_fn (t)
5513 && !type_dependent_expression_p (t)
5514 && !decl_maybe_constant_var_p (t)
5516 || !CP_TYPE_CONST_NON_VOLATILE_P (TREE_TYPE (t))
5517 || (DECL_INITIAL (t)
5518 && !DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (t)))
5519 && COMPLETE_TYPE_P (TREE_TYPE (t))
5520 && !is_really_empty_class (TREE_TYPE (t)))
5522 if (flags & tf_error)
5523 non_const_var_error (t);
5530 case VIEW_CONVERT_EXPR:
5531 /* -- a reinterpret_cast. FIXME not implemented, and this rule
5532 may change to something more specific to type-punning (DR 1312). */
5534 tree from = TREE_OPERAND (t, 0);
5535 if (POINTER_TYPE_P (TREE_TYPE (t))
5536 && TREE_CODE (from) == INTEGER_CST
5537 && !integer_zerop (from))
5539 if (flags & tf_error)
5540 error_at (loc, "reinterpret_cast from integer to pointer");
5543 return (RECUR (from, TREE_CODE (t) != VIEW_CONVERT_EXPR));
5546 case ADDRESSOF_EXPR:
5547 /* This is like ADDR_EXPR, except it won't form pointer-to-member. */
5548 t = TREE_OPERAND (t, 0);
5549 goto handle_addr_expr;
5552 /* -- a unary operator & that is applied to an lvalue that
5553 designates an object with thread or automatic storage
5555 t = TREE_OPERAND (t, 0);
5557 if (TREE_CODE (t) == OFFSET_REF && PTRMEM_OK_P (t))
5558 /* A pointer-to-member constant. */
5563 /* FIXME adjust when issue 1197 is fully resolved. For now don't do
5564 any checking here, as we might dereference the pointer later. If
5565 we remove this code, also remove check_automatic_or_tls. */
5566 i = check_automatic_or_tls (t);
5571 if (flags & tf_error)
5572 error ("address-of an object %qE with thread local or "
5573 "automatic storage is not a constant expression", t);
5577 return RECUR (t, any);
5585 /* -- a class member access unless its postfix-expression is
5586 of literal type or of pointer to literal type. */
5587 /* This test would be redundant, as it follows from the
5588 postfix-expression being a potential constant expression. */
5589 if (type_unknown_p (t))
5591 return RECUR (TREE_OPERAND (t, 0), want_rval);
5593 case EXPR_PACK_EXPANSION:
5594 return RECUR (PACK_EXPANSION_PATTERN (t), want_rval);
5598 tree x = TREE_OPERAND (t, 0);
5600 if (is_this_parameter (x) && !is_capture_proxy (x))
5602 if (!var_in_maybe_constexpr_fn (x))
5604 if (flags & tf_error)
5605 error_at (loc, "use of %<this%> in a constant expression");
5610 return RECUR (x, rval);
5613 case STATEMENT_LIST:
5615 tree_stmt_iterator i;
5616 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
5618 if (!RECUR (tsi_stmt (i), any))
5626 if (cxx_dialect < cxx14)
5628 if (!RECUR (TREE_OPERAND (t, 0), any))
5630 if (!RECUR (TREE_OPERAND (t, 1), rval))
5635 if (cxx_dialect < cxx14)
5637 if (!RECUR (TREE_OPERAND (t, 0), rval))
5639 if (!RECUR (TREE_OPERAND (t, 2), rval))
5644 if (!RECUR (DO_COND (t), rval))
5646 if (!RECUR (DO_BODY (t), any))
5651 if (!RECUR (FOR_INIT_STMT (t), any))
5653 if (!RECUR (FOR_COND (t), rval))
5655 if (!RECUR (FOR_EXPR (t), any))
5657 if (!RECUR (FOR_BODY (t), any))
5661 case RANGE_FOR_STMT:
5662 if (!RECUR (RANGE_FOR_EXPR (t), any))
5664 if (!RECUR (RANGE_FOR_BODY (t), any))
5669 if (!RECUR (WHILE_COND (t), rval))
5671 if (!RECUR (WHILE_BODY (t), any))
5676 if (!RECUR (SWITCH_STMT_COND (t), rval))
5678 /* FIXME we don't check SWITCH_STMT_BODY currently, because even
5679 unreachable labels would be checked. */
5683 return RECUR (STMT_EXPR_STMT (t), rval);
5686 if (cxx_dialect >= cxx17)
5687 /* In C++17 lambdas can be constexpr, don't give up yet. */
5689 else if (flags & tf_error)
5690 error_at (loc, "lambda-expression is not a constant expression "
5694 case DYNAMIC_CAST_EXPR:
5695 case PSEUDO_DTOR_EXPR:
5699 case VEC_DELETE_EXPR:
5705 case OMP_DISTRIBUTE:
5708 case OMP_TARGET_DATA:
5717 case OMP_TARGET_UPDATE:
5718 case OMP_TARGET_ENTER_DATA:
5719 case OMP_TARGET_EXIT_DATA:
5721 case OMP_ATOMIC_READ:
5722 case OMP_ATOMIC_CAPTURE_OLD:
5723 case OMP_ATOMIC_CAPTURE_NEW:
5727 case OACC_HOST_DATA:
5731 case OACC_ENTER_DATA:
5732 case OACC_EXIT_DATA:
5734 /* GCC internal stuff. */
5737 case TRANSACTION_EXPR:
5739 case AT_ENCODE_EXPR:
5741 if (flags & tf_error)
5742 error_at (loc, "expression %qE is not a constant expression", t);
5746 /* -- a typeid expression whose operand is of polymorphic
5749 tree e = TREE_OPERAND (t, 0);
5750 if (!TYPE_P (e) && !type_dependent_expression_p (e)
5751 && TYPE_POLYMORPHIC_P (TREE_TYPE (e)))
5753 if (flags & tf_error)
5754 error_at (loc, "typeid-expression is not a constant expression "
5755 "because %qE is of polymorphic type", e);
5761 case POINTER_DIFF_EXPR:
5775 case PREINCREMENT_EXPR:
5776 case POSTINCREMENT_EXPR:
5777 case PREDECREMENT_EXPR:
5778 case POSTDECREMENT_EXPR:
5779 if (cxx_dialect < cxx14)
5785 if (TYPE_P (TREE_OPERAND (t, 0)))
5791 case FIX_TRUNC_EXPR:
5795 case TRUTH_NOT_EXPR:
5796 case FIXED_CONVERT_EXPR:
5797 case UNARY_PLUS_EXPR:
5798 case UNARY_LEFT_FOLD_EXPR:
5799 case UNARY_RIGHT_FOLD_EXPR:
5801 return RECUR (TREE_OPERAND (t, 0), rval);
5804 case CONST_CAST_EXPR:
5805 case STATIC_CAST_EXPR:
5806 case REINTERPRET_CAST_EXPR:
5807 case IMPLICIT_CONV_EXPR:
5808 if (cxx_dialect < cxx11
5809 && !dependent_type_p (TREE_TYPE (t))
5810 && !INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (t)))
5811 /* In C++98, a conversion to non-integral type can't be part of a
5812 constant expression. */
5814 if (flags & tf_error)
5816 "cast to non-integral type %qT in a constant expression",
5820 /* This might be a conversion from a class to a (potentially) literal
5821 type. Let's consider it potentially constant since the conversion
5822 might be a constexpr user-defined conversion. */
5823 else if (cxx_dialect >= cxx11
5824 && (dependent_type_p (TREE_TYPE (t))
5825 || !COMPLETE_TYPE_P (TREE_TYPE (t))
5826 || literal_type_p (TREE_TYPE (t)))
5827 && TREE_OPERAND (t, 0))
5829 tree type = TREE_TYPE (TREE_OPERAND (t, 0));
5830 /* If this is a dependent type, it could end up being a class
5831 with conversions. */
5832 if (type == NULL_TREE || WILDCARD_TYPE_P (type))
5834 /* Or a non-dependent class which has conversions. */
5835 else if (CLASS_TYPE_P (type)
5836 && (TYPE_HAS_CONVERSION (type) || dependent_scope_p (type)))
5840 return (RECUR (TREE_OPERAND (t, 0),
5841 TREE_CODE (TREE_TYPE (t)) != REFERENCE_TYPE));
5844 return RECUR (BIND_EXPR_BODY (t), want_rval);
5846 case CLEANUP_POINT_EXPR:
5847 case MUST_NOT_THROW_EXPR:
5848 case TRY_CATCH_EXPR:
5853 case NON_DEPENDENT_EXPR:
5854 /* For convenience. */
5858 return RECUR (TREE_OPERAND (t, 0), want_rval);
5861 tmp = DECL_EXPR_DECL (t);
5862 if (VAR_P (tmp) && !DECL_ARTIFICIAL (tmp))
5864 if (TREE_STATIC (tmp))
5866 if (flags & tf_error)
5867 error_at (DECL_SOURCE_LOCATION (tmp), "%qD declared "
5868 "%<static%> in %<constexpr%> context", tmp);
5871 else if (CP_DECL_THREAD_LOCAL_P (tmp))
5873 if (flags & tf_error)
5874 error_at (DECL_SOURCE_LOCATION (tmp), "%qD declared "
5875 "%<thread_local%> in %<constexpr%> context", tmp);
5878 else if (!check_for_uninitialized_const_var
5879 (tmp, /*constexpr_context_p=*/true, flags))
5882 return RECUR (tmp, want_rval);
5884 case TRY_FINALLY_EXPR:
5885 return (RECUR (TREE_OPERAND (t, 0), want_rval)
5886 && RECUR (TREE_OPERAND (t, 1), any));
5889 return RECUR (TREE_OPERAND (t, 1), want_rval);
5892 if (!TARGET_EXPR_DIRECT_INIT_P (t)
5893 && !literal_type_p (TREE_TYPE (t)))
5895 if (flags & tf_error)
5897 error_at (loc, "temporary of non-literal type %qT in a "
5898 "constant expression", TREE_TYPE (t));
5899 explain_non_literal_class (TREE_TYPE (t));
5905 return RECUR (TREE_OPERAND (t, 1), rval);
5909 vec<constructor_elt, va_gc> *v = CONSTRUCTOR_ELTS (t);
5910 constructor_elt *ce;
5911 for (i = 0; vec_safe_iterate (v, i, &ce); ++i)
5912 if (!RECUR (ce->value, want_rval))
5919 gcc_assert (TREE_PURPOSE (t) == NULL_TREE
5920 || DECL_P (TREE_PURPOSE (t)));
5921 if (!RECUR (TREE_VALUE (t), want_rval))
5923 if (TREE_CHAIN (t) == NULL_TREE)
5925 return RECUR (TREE_CHAIN (t), want_rval);
5928 case TRUNC_DIV_EXPR:
5930 case FLOOR_DIV_EXPR:
5931 case ROUND_DIV_EXPR:
5932 case TRUNC_MOD_EXPR:
5934 case ROUND_MOD_EXPR:
5936 tree denom = TREE_OPERAND (t, 1);
5937 if (!RECUR (denom, rval))
5939 /* We can't call cxx_eval_outermost_constant_expr on an expression
5940 that hasn't been through instantiate_non_dependent_expr yet. */
5941 if (!processing_template_decl)
5942 denom = cxx_eval_outermost_constant_expr (denom, true);
5943 if (integer_zerop (denom))
5945 if (flags & tf_error)
5946 error ("division by zero is not a constant expression");
5952 return RECUR (TREE_OPERAND (t, 0), want_rval);
5958 /* check_return_expr sometimes wraps a TARGET_EXPR in a
5959 COMPOUND_EXPR; don't get confused. Also handle EMPTY_CLASS_EXPR
5960 introduced by build_call_a. */
5961 tree op0 = TREE_OPERAND (t, 0);
5962 tree op1 = TREE_OPERAND (t, 1);
5964 if ((TREE_CODE (op0) == TARGET_EXPR && op1 == TARGET_EXPR_SLOT (op0))
5965 || TREE_CODE (op1) == EMPTY_CLASS_EXPR)
5966 return RECUR (op0, want_rval);
5971 /* If the first operand is the non-short-circuit constant, look at
5972 the second operand; otherwise we only care about the first one for
5974 case TRUTH_AND_EXPR:
5975 case TRUTH_ANDIF_EXPR:
5976 tmp = boolean_true_node;
5979 case TRUTH_ORIF_EXPR:
5980 tmp = boolean_false_node;
5983 tree op = TREE_OPERAND (t, 0);
5984 if (!RECUR (op, rval))
5986 if (!processing_template_decl)
5987 op = cxx_eval_outermost_constant_expr (op, true);
5988 if (tree_int_cst_equal (op, tmp))
5989 return RECUR (TREE_OPERAND (t, 1), rval);
5996 case POINTER_PLUS_EXPR:
5998 case EXACT_DIV_EXPR:
6008 case TRUTH_XOR_EXPR:
6009 case UNORDERED_EXPR:
6022 case ARRAY_RANGE_REF:
6026 case BINARY_LEFT_FOLD_EXPR:
6027 case BINARY_RIGHT_FOLD_EXPR:
6029 for (i = 0; i < 2; ++i)
6030 if (!RECUR (TREE_OPERAND (t, i), want_rval))
6036 for (i = 0; i < 3; ++i)
6037 if (!RECUR (TREE_OPERAND (t, i), true))
6042 if (COND_EXPR_IS_VEC_DELETE (t))
6044 if (flags & tf_error)
6045 error_at (loc, "%<delete[]%> is not a constant expression");
6051 /* If the condition is a known constant, we know which of the legs we
6052 care about; otherwise we only require that the condition and
6053 either of the legs be potentially constant. */
6054 tmp = TREE_OPERAND (t, 0);
6055 if (!RECUR (tmp, rval))
6057 if (!processing_template_decl)
6058 tmp = cxx_eval_outermost_constant_expr (tmp, true);
6059 if (integer_zerop (tmp))
6060 return RECUR (TREE_OPERAND (t, 2), want_rval);
6061 else if (TREE_CODE (tmp) == INTEGER_CST)
6062 return RECUR (TREE_OPERAND (t, 1), want_rval);
6063 for (i = 1; i < 3; ++i)
6064 if (potential_constant_expression_1 (TREE_OPERAND (t, i),
6065 want_rval, strict, now, tf_none))
6067 if (flags & tf_error)
6068 error_at (loc, "expression %qE is not a constant expression", t);
6072 if (VEC_INIT_EXPR_IS_CONSTEXPR (t))
6074 if (flags & tf_error)
6076 error_at (loc, "non-constant array initialization");
6077 diagnose_non_constexpr_vec_init (t);
6083 /* We can see these in statement-expressions. */
6087 case EMPTY_CLASS_EXPR:
6093 tree *target = &TREE_OPERAND (t, 0);
6094 /* Gotos representing break and continue are OK. */
6095 if (breaks (target) || continues (target))
6097 if (flags & tf_error)
6098 error_at (loc, "%<goto%> is not a constant expression");
6103 return RECUR (TREE_OPERAND (t, 0), rval);
6106 if (objc_is_property_ref (t))
6109 sorry ("unexpected AST of kind %s", get_tree_code_name (TREE_CODE (t)));
6116 /* The main entry point to the above. */
6119 potential_constant_expression (tree t)
6121 return potential_constant_expression_1 (t, false, true, false, tf_none);
6124 /* As above, but require a constant rvalue. */
6127 potential_rvalue_constant_expression (tree t)
6129 return potential_constant_expression_1 (t, true, true, false, tf_none);
6132 /* Like above, but complain about non-constant expressions. */
6135 require_potential_constant_expression (tree t)
6137 return potential_constant_expression_1 (t, false, true, false,
6138 tf_warning_or_error);
6141 /* Cross product of the above. */
6144 require_potential_rvalue_constant_expression (tree t)
6146 return potential_constant_expression_1 (t, true, true, false,
6147 tf_warning_or_error);
6150 /* Like above, but don't consider PARM_DECL a potential_constant_expression. */
6153 require_rvalue_constant_expression (tree t)
6155 return potential_constant_expression_1 (t, true, true, true,
6156 tf_warning_or_error);
6159 /* Like potential_constant_expression, but don't consider possible constexpr
6160 substitution of the current function. That is, PARM_DECL qualifies under
6161 potential_constant_expression, but not here.
6163 This is basically what you can check when any actual constant values might
6164 be value-dependent. */
6167 is_constant_expression (tree t)
6169 return potential_constant_expression_1 (t, false, true, true, tf_none);
6172 /* Like above, but complain about non-constant expressions. */
6175 require_constant_expression (tree t)
6177 return potential_constant_expression_1 (t, false, true, true,
6178 tf_warning_or_error);
6181 /* Like is_constant_expression, but allow const variables that are not allowed
6182 under constexpr rules. */
6185 is_static_init_expression (tree t)
6187 return potential_constant_expression_1 (t, false, false, true, tf_none);
6190 /* Returns true if T is a potential constant expression that is not
6191 instantiation-dependent, and therefore a candidate for constant folding even
6195 is_nondependent_constant_expression (tree t)
6197 return (!type_unknown_p (t)
6198 && !BRACE_ENCLOSED_INITIALIZER_P (t)
6199 && is_constant_expression (t)
6200 && !instantiation_dependent_expression_p (t));
6203 /* Returns true if T is a potential static initializer expression that is not
6204 instantiation-dependent. */
6207 is_nondependent_static_init_expression (tree t)
6209 return (!type_unknown_p (t)
6210 && !BRACE_ENCLOSED_INITIALIZER_P (t)
6211 && is_static_init_expression (t)
6212 && !instantiation_dependent_expression_p (t));
6215 /* Finalize constexpr processing after parsing. */
6218 fini_constexpr (void)
6220 /* The contexpr call and fundef copies tables are no longer needed. */
6221 constexpr_call_table = NULL;
6222 fundef_copies_table = NULL;
6225 #include "gt-cp-constexpr.h"