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Use atomics in guard.cc. 

This provides proper definitions for _GLIBCXX_READ_MEM_BARRIER and
_GLIBCXX_WRITE_MEM_BARRIER, rewrites the guards in terms of proper
atomic extensions and removes internal uses of
_GLIBCXX_READ_MEM_BARRIER and _GLIBCXX_WRITE_MEM_BARRIER and replaces
them with equivalent atomics.

2015-06-12  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>

	PR target/66200
	PR c++/66192
	* * config/cpu/generic/atomic_word.h (_GLIBCXX_READ_MEM_BARRIER): Define
        (_GLIBCXX_WRITE_MEM_BARRIER): Likewise
        * include/bits/shared_ptr_base.h: Use ACQ_REL barrier.
        * include/ext/atomicity.h: Likewise.
        * include/tr1/shared_ptr.h: Likewise.
        * libsupc++/guard.cc (__test_and_acquire): Rewrite with atomics.
        Update comment.
        (__set_and_release): Likewise.
        * testsuite/20_util/shared_ptr/cons/43820_neg.cc (test01): Adjust for
	line numbers.
        * testsuite/20_util/shared_ptr/cons/void_neg.cc: Likewise.
        * testsuite/tr1/2_general_utilities/shared_ptr/cons/43820_neg.cc:
	Likewise.

From-SVN: r224411
This commit is contained in:
Ramana Radhakrishnan 2015-06-12 09:49:41 +00:00 committed by Ramana Radhakrishnan
parent 40ad260d6c
commit 57e6d9be77
9 changed files with 46 additions and 30 deletions
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18
libstdc++-v3/ChangeLog
View File

@ -1,3 +1,21 @@
2015-06-12 Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>
PR target/66200
PR c++/66192
* * config/cpu/generic/atomic_word.h (_GLIBCXX_READ_MEM_BARRIER): Define
(_GLIBCXX_WRITE_MEM_BARRIER): Likewise
* include/bits/shared_ptr_base.h: Use ACQ_REL barrier.
* include/ext/atomicity.h: Likewise.
* include/tr1/shared_ptr.h: Likewise.
* libsupc++/guard.cc (__test_and_acquire): Rewrite with atomics.
Update comment.
(__set_and_release): Likewise.
* testsuite/20_util/shared_ptr/cons/43820_neg.cc (test01): Adjust for
line numbers.
* testsuite/20_util/shared_ptr/cons/void_neg.cc: Likewise.
* testsuite/tr1/2_general_utilities/shared_ptr/cons/43820_neg.cc:
Likewise.
2015-06-12 Jonathan Wakely <jwakely@redhat.com>
* include/std/tuple (__is_tuple_like_impl): Disambiguate array in

15
libstdc++-v3/config/cpu/generic/atomic_word.h
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@ -31,17 +31,10 @@
typedef int _Atomic_word;
// Define these two macros using the appropriate memory barrier for the target.
// The commented out versions below are the defaults.
// See ia64/atomic_word.h for an alternative approach.
// This one prevents loads from being hoisted across the barrier;
// in other words, this is a Load-Load acquire barrier.
// This is necessary iff TARGET_RELAXED_ORDERING is defined in tm.h.
// #define _GLIBCXX_READ_MEM_BARRIER __asm __volatile ("":::"memory")
// This one prevents stores from being sunk across the barrier; in other
// words, a Store-Store release barrier.
// #define _GLIBCXX_WRITE_MEM_BARRIER __asm __volatile ("":::"memory")
// This is a memory order acquire fence.
#define _GLIBCXX_READ_MEM_BARRIER __atomic_thread_fence (__ATOMIC_ACQUIRE)
// This is a memory order release fence.
#define _GLIBCXX_WRITE_MEM_BARRIER __atomic_thread_fence (__ATOMIC_RELEASE)
#endif

6
libstdc++-v3/include/bits/shared_ptr_base.h
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@ -154,8 +154,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html
if (_Mutex_base<_Lp>::_S_need_barriers)
{
_GLIBCXX_READ_MEM_BARRIER;
_GLIBCXX_WRITE_MEM_BARRIER;
__atomic_thread_fence (__ATOMIC_ACQ_REL);
}
// Be race-detector-friendly. For more info see bits/c++config.
@ -185,8 +184,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
// See _M_release(),
// destroy() must observe results of dispose()
_GLIBCXX_READ_MEM_BARRIER;
_GLIBCXX_WRITE_MEM_BARRIER;
__atomic_thread_fence (__ATOMIC_ACQ_REL);
}
_M_destroy();
}

4
libstdc++-v3/include/ext/atomicity.h
View File

@ -108,10 +108,10 @@ _GLIBCXX_END_NAMESPACE_VERSION
// that the compiler doesn't reorder memory accesses across the
// barriers.
#ifndef _GLIBCXX_READ_MEM_BARRIER
#define _GLIBCXX_READ_MEM_BARRIER __asm __volatile ("":::"memory")
#define _GLIBCXX_READ_MEM_BARRIER __atomic_thread_fence (__ATOMIC_ACQUIRE)
#endif
#ifndef _GLIBCXX_WRITE_MEM_BARRIER
#define _GLIBCXX_WRITE_MEM_BARRIER __asm __volatile ("":::"memory")
#define _GLIBCXX_WRITE_MEM_BARRIER __atomic_thread_fence (__ATOMIC_RELEASE)
#endif
#endif

6
libstdc++-v3/include/tr1/shared_ptr.h
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@ -145,8 +145,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html
if (_Mutex_base<_Lp>::_S_need_barriers)
{
_GLIBCXX_READ_MEM_BARRIER;
_GLIBCXX_WRITE_MEM_BARRIER;
__atomic_thread_fence (__ATOMIC_ACQ_REL);
}
// Be race-detector-friendly. For more info see bits/c++config.
@ -176,8 +175,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
// See _M_release(),
// destroy() must observe results of dispose()
_GLIBCXX_READ_MEM_BARRIER;
_GLIBCXX_WRITE_MEM_BARRIER;
__atomic_thread_fence (__ATOMIC_ACQ_REL);
}
_M_destroy();
}

19
libstdc++-v3/libsupc++/guard.cc
View File

@ -107,22 +107,31 @@ namespace
# endif
# ifndef _GLIBCXX_GUARD_TEST_AND_ACQUIRE
// Test the guard variable with a memory load with
// acquire semantics.
inline bool
__test_and_acquire (__cxxabiv1::__guard *g)
{
bool b = _GLIBCXX_GUARD_TEST (g);
_GLIBCXX_READ_MEM_BARRIER;
return b;
unsigned char __c;
unsigned char *__p = reinterpret_cast<unsigned char *>(g);
__atomic_load (__p, &__c, __ATOMIC_ACQUIRE);
return _GLIBCXX_GUARD_TEST(&__c);
}
# define _GLIBCXX_GUARD_TEST_AND_ACQUIRE(G) __test_and_acquire (G)
# endif
# ifndef _GLIBCXX_GUARD_SET_AND_RELEASE
// Set the guard variable to 1 with memory order release semantics.
inline void
__set_and_release (__cxxabiv1::__guard *g)
{
_GLIBCXX_WRITE_MEM_BARRIER;
_GLIBCXX_GUARD_SET (g);
unsigned char *__p = reinterpret_cast<unsigned char *>(g);
unsigned char val = 1;
__atomic_store (__p, &val, __ATOMIC_RELEASE);
}
# define _GLIBCXX_GUARD_SET_AND_RELEASE(G) __set_and_release (G)
# endif

2
libstdc++-v3/testsuite/20_util/shared_ptr/cons/43820_neg.cc
View File

@ -32,7 +32,7 @@ void test01()
{
X* px = 0;
std::shared_ptr<X> p1(px); // { dg-error "here" }
// { dg-error "incomplete" "" { target *-*-* } 891 }
// { dg-error "incomplete" "" { target *-*-* } 889 }
std::shared_ptr<X> p9(ap()); // { dg-error "here" }
// { dg-error "incomplete" "" { target *-*-* } 307 }

2
libstdc++-v3/testsuite/20_util/shared_ptr/cons/void_neg.cc
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@ -25,5 +25,5 @@
void test01()
{
std::shared_ptr<void> p((void*)nullptr); // { dg-error "here" }
// { dg-error "incomplete" "" { target *-*-* } 890 }
// { dg-error "incomplete" "" { target *-*-* } 888 }
}

4
libstdc++-v3/testsuite/tr1/2_general_utilities/shared_ptr/cons/43820_neg.cc
View File

@ -32,8 +32,8 @@ void test01()
{
X* px = 0;
std::tr1::shared_ptr<X> p1(px); // { dg-error "here" }
// { dg-error "incomplete" "" { target *-*-* } 556 }
// { dg-error "incomplete" "" { target *-*-* } 554 }
std::tr1::shared_ptr<X> p9(ap()); // { dg-error "here" }
// { dg-error "incomplete" "" { target *-*-* } 595 }
// { dg-error "incomplete" "" { target *-*-* } 593 }
}