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re PR libstdc++/62259 (atomic class doesn't enforce required alignment on powerpc64)

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PR libstdc++/62259
	PR libstdc++/65147
	* include/std/atomic (atomic<T>): Increase alignment for types with
	the same size as one of the integral types.
	* testsuite/29_atomics/atomic/60695.cc: Adjust dg-error line number.
	* testsuite/29_atomics/atomic/62259.cc: New.

From-SVN: r221703
This commit is contained in:
Jonathan Wakely 2015-03-26 19:27:02 +00:00 committed by Jonathan Wakely
parent 552b2afefb
commit 4280698d09
4 changed files with 85 additions and 2 deletions
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9
libstdc++-v3/ChangeLog
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@ -1,3 +1,12 @@
2015-03-26 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/62259
PR libstdc++/65147
* include/std/atomic (atomic<T>): Increase alignment for types with
the same size as one of the integral types.
* testsuite/29_atomics/atomic/60695.cc: Adjust dg-error line number.
* testsuite/29_atomics/atomic/62259.cc: New.
2015-03-26 Richard Henderson <rth@redhat.com>
PR libstdc++/65033

18
libstdc++-v3/include/std/atomic
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@ -165,7 +165,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
struct atomic
{
private:
_Tp _M_i;
// Align 1/2/4/8/16-byte types the same as integer types of that size.
// This matches the alignment effects of the C11 _Atomic qualifier.
static constexpr int _S_min_alignment
= sizeof(_Tp) == sizeof(char) ? alignof(char)
: sizeof(_Tp) == sizeof(short) ? alignof(short)
: sizeof(_Tp) == sizeof(int) ? alignof(int)
: sizeof(_Tp) == sizeof(long) ? alignof(long)
: sizeof(_Tp) == sizeof(long long) ? alignof(long long)
#ifdef _GLIBCXX_USE_INT128
: sizeof(_Tp) == sizeof(__int128) ? alignof(__int128)
#endif
: 0;
static constexpr int _S_alignment
= _S_min_alignment > alignof(_Tp) ? _S_min_alignment : alignof(_Tp);
alignas(_S_alignment) _Tp _M_i;
static_assert(__is_trivially_copyable(_Tp),
"std::atomic requires a trivially copyable type");

2
libstdc++-v3/testsuite/29_atomics/atomic/60695.cc
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@ -27,4 +27,4 @@ struct X {
char stuff[0]; // GNU extension, type has zero size
};
std::atomic<X> a; // { dg-error "not supported" "" { target *-*-* } 173 }
std::atomic<X> a; // { dg-error "not supported" "" { target *-*-* } 189 }

58
libstdc++-v3/testsuite/29_atomics/atomic/62259.cc Normal file
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@ -0,0 +1,58 @@
// Copyright (C) 2015 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-require-atomic-builtins "" }
// { dg-require-cstdint "" }
// { dg-options "-std=gnu++11" }
// { dg-do compile }
#include <atomic>
#include <cstdint>
using std::int32_t;
using std::int64_t;
// libstdc++/62259
struct twoints {
int32_t a;
int32_t b;
};
static_assert( alignof(std::atomic<twoints>) == alignof(int64_t),
"std::atomic not suitably aligned" );
// libstdc++/65147
struct power_of_two_obj {
char c [8];
};
std::atomic<power_of_two_obj> obj1;
static_assert( alignof(obj1) == alignof(int64_t),
"std::atomic not suitably aligned" );
struct container_struct {
char c[1];
std::atomic<power_of_two_obj> ao;
};
container_struct obj2;
static_assert( alignof(obj2.ao) == alignof(int64_t),
"std::atomic not suitably aligned" );