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PR c++/85873 - constant initializer_list array not in .rodata.

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* tree.c (build_target_expr): Set TREE_READONLY.
	* call.c (set_up_extended_ref_temp): Set TREE_READONLY.

From-SVN: r260969
This commit is contained in:
Jason Merrill 2018-05-30 13:33:06 -04:00 committed by Jason Merrill
parent cd7fa7a74b
commit 5603790dbf
4 changed files with 35 additions and 4 deletions
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4
gcc/cp/ChangeLog
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@ -1,5 +1,9 @@
2018-05-30 Jason Merrill <jason@redhat.com>
PR c++/85873 - constant initializer_list array not in .rodata.
* tree.c (build_target_expr): Set TREE_READONLY.
* call.c (set_up_extended_ref_temp): Set TREE_READONLY.
* parser.c (cp_parser_check_condition_declarator): Handle
cp_error_declarator.

6
gcc/cp/call.c
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@ -10923,13 +10923,11 @@ set_up_extended_ref_temp (tree decl, tree expr, vec<tree, va_gc> **cleanups,
lvalue-rvalue conversion applied to "a glvalue of literal type
that refers to a non-volatile temporary object initialized
with a constant expression". Rather than try to communicate
that this VAR_DECL is a temporary, just mark it constexpr.
Currently this is only useful for initializer_list temporaries,
since reference vars can't appear in constant expressions. */
that this VAR_DECL is a temporary, just mark it constexpr. */
DECL_DECLARED_CONSTEXPR_P (var) = true;
DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (var) = true;
TREE_CONSTANT (var) = true;
TREE_READONLY (var) = true;
}
DECL_INITIAL (var) = init;
init = NULL_TREE;

8
gcc/cp/tree.c
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@ -461,6 +461,14 @@ build_target_expr (tree decl, tree value, tsubst_flags_t complain)
|| useless_type_conversion_p (TREE_TYPE (decl),
TREE_TYPE (value)));
/* Set TREE_READONLY for optimization, such as gimplify_init_constructor
moving a constant aggregate into .rodata. */
if (CP_TYPE_CONST_NON_VOLATILE_P (type)
&& !TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type)
&& !VOID_TYPE_P (TREE_TYPE (value))
&& reduced_constant_expression_p (value))
TREE_READONLY (decl) = true;
if (complain & tf_no_cleanup)
/* The caller is building a new-expr and does not need a cleanup. */
t = NULL_TREE;

21
gcc/testsuite/g++.dg/tree-ssa/array-temp1.C Normal file
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@ -0,0 +1,21 @@
// PR c++/85873
// Test that these array temporaries are promoted to static variables as an
// optimization.
// { dg-do compile { target c++11 } }
// { dg-additional-options -fdump-tree-gimple }
// { dg-final { scan-tree-dump-not "= 42" "gimple" } }
#include <initializer_list>
int f()
{
using AR = const int[];
return AR{ 1,42,3,4,5,6,7,8,9,0 }[5];
}
int g()
{
std::initializer_list<int> a = {1,42,3};
return a.begin()[0];
}