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[Test patch] Inline hot functions in libcxx shared_ptr 

Moves hot functions such as atomic add into the memory header file
so that they can be inlined, which brings performance benefits.

Patch by Kevin Hu, Aditya Kumar, Sebastian Pop

Differential Revision: https://reviews.llvm.org/D24991

llvm-svn: 292184
This commit is contained in:
Kevin Hu 2017-01-17 02:46:33 +00:00
parent 957fbf1f9f
commit f08de52d77
2 changed files with 77 additions and 35 deletions
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74
libcxx/include/memory
View File

@ -3681,6 +3681,39 @@ uninitialized_move_n(_InputIt __first, _Size __n, _ForwardIt __first_res) {
#endif // _LIBCPP_STD_VER > 14
// NOTE: Relaxed and acq/rel atomics (for increment and decrement respectively)
// should be sufficient for thread safety.
// See https://llvm.org/bugs/show_bug.cgi?id=22803
#if defined(__clang__) && __has_builtin(__atomic_add_fetch) \
&& defined(__ATOMIC_RELAXED) \
&& defined(__ATOMIC_ACQ_REL)
# define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT
#elif !defined(__clang__) && defined(_GNUC_VER) && _GNUC_VER >= 407
# define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT
#endif
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY _Tp
__libcpp_atomic_refcount_increment(_Tp& __t) _NOEXCEPT
{
#if defined(_LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT) && !defined(_LIBCPP_HAS_NO_THREADS)
return __atomic_add_fetch(&__t, 1, __ATOMIC_RELAXED);
#else
return __t += 1;
#endif
}
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY _Tp
__libcpp_atomic_refcount_decrement(_Tp& __t) _NOEXCEPT
{
#if defined(_LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT) && !defined(_LIBCPP_HAS_NO_THREADS)
return __atomic_add_fetch(&__t, -1, __ATOMIC_ACQ_REL);
#else
return __t -= 1;
#endif
}
class _LIBCPP_EXCEPTION_ABI bad_weak_ptr
: public std::exception
{
@ -3717,8 +3750,23 @@ public:
explicit __shared_count(long __refs = 0) _NOEXCEPT
: __shared_owners_(__refs) {}
void __add_shared() _NOEXCEPT;
bool __release_shared() _NOEXCEPT;
#ifdef _LIBCPP_BUILDING_MEMORY
_LIBCPP_FUNC_VIS void __add_shared() _NOEXCEPT;
_LIBCPP_FUNC_VIS bool __release_shared() _NOEXCEPT;
#else
_LIBCPP_INLINE_VISIBILITY
void __add_shared() _NOEXCEPT {
__libcpp_atomic_refcount_increment(__shared_owners_);
}
_LIBCPP_INLINE_VISIBILITY
bool __release_shared() _NOEXCEPT {
if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1) {
__on_zero_shared();
return true;
}
return false;
}
#endif
_LIBCPP_INLINE_VISIBILITY
long use_count() const _NOEXCEPT {
return __libcpp_relaxed_load(&__shared_owners_) + 1;
@ -3739,9 +3787,25 @@ protected:
virtual ~__shared_weak_count();
public:
void __add_shared() _NOEXCEPT;
void __add_weak() _NOEXCEPT;
void __release_shared() _NOEXCEPT;
#ifdef _LIBCPP_BUILDING_MEMORY
_LIBCPP_FUNC_VIS void __add_shared() _NOEXCEPT;
_LIBCPP_FUNC_VIS void __add_weak() _NOEXCEPT;
_LIBCPP_FUNC_VIS void __release_shared() _NOEXCEPT;
#else
_LIBCPP_INLINE_VISIBILITY
void __add_shared() _NOEXCEPT {
__shared_count::__add_shared();
}
_LIBCPP_INLINE_VISIBILITY
void __add_weak() _NOEXCEPT {
__libcpp_atomic_refcount_increment(__shared_weak_owners_);
}
_LIBCPP_INLINE_VISIBILITY
void __release_shared() _NOEXCEPT {
if (__shared_count::__release_shared())
__release_weak();
}
#endif
void __release_weak() _NOEXCEPT;
_LIBCPP_INLINE_VISIBILITY
long use_count() const _NOEXCEPT {return __shared_count::use_count();}

38
libcxx/src/memory.cpp
View File

@ -17,28 +17,6 @@
_LIBCPP_BEGIN_NAMESPACE_STD
namespace
{
// NOTE: Relaxed and acq/rel atomics (for increment and decrement respectively)
// should be sufficient for thread safety.
// See https://llvm.org/bugs/show_bug.cgi?id=22803
template <class T>
inline T
increment(T& t) _NOEXCEPT
{
return __libcpp_atomic_add(&t, 1, _AO_Relaxed);
}
template <class T>
inline T
decrement(T& t) _NOEXCEPT
{
return __libcpp_atomic_add(&t, -1, _AO_Acq_Rel);
}
} // namespace
const allocator_arg_t allocator_arg = allocator_arg_t();
bad_weak_ptr::~bad_weak_ptr() _NOEXCEPT {}
@ -53,16 +31,20 @@ __shared_count::~__shared_count()
{
}
__shared_weak_count::~__shared_weak_count()
{
}
void
__shared_count::__add_shared() _NOEXCEPT
{
increment(__shared_owners_);
__libcpp_atomic_refcount_increment(__shared_owners_);
}
bool
__shared_count::__release_shared() _NOEXCEPT
{
if (decrement(__shared_owners_) == -1)
if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1)
{
__on_zero_shared();
return true;
@ -70,10 +52,6 @@ __shared_count::__release_shared() _NOEXCEPT
return false;
}
__shared_weak_count::~__shared_weak_count()
{
}
void
__shared_weak_count::__add_shared() _NOEXCEPT
{
@ -83,7 +61,7 @@ __shared_weak_count::__add_shared() _NOEXCEPT
void
__shared_weak_count::__add_weak() _NOEXCEPT
{
increment(__shared_weak_owners_);
__libcpp_atomic_refcount_increment(__shared_weak_owners_);
}
void
@ -124,7 +102,7 @@ __shared_weak_count::__release_weak() _NOEXCEPT
//__libcpp_atomic_store(&__shared_weak_owners_, -1, _AO_Release);
__on_zero_shared_weak();
}
else if (decrement(__shared_weak_owners_) == -1)
else if (__libcpp_atomic_refcount_decrement(__shared_weak_owners_) == -1)
__on_zero_shared_weak();
}