LineageOS/android_external_libcxx
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Mark libc++ internal globals with _LIBCPP_SAFE_STATIC.

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This patch applies the _LIBCPP_SAFE_STATIC attribute to internal globals,
most of which are locking primitives, in order to ensure that they can
safely be used during program startup.

This patch also fixes an unsafe static init issue with the global locks
used to implement atomic operations on shared pointers. Previously the
locks were initialized using a dynamically initialized pointer, so it was
possible that the pointer was uninitialized.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@282640 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Fiselier
2016-09-28 22:08:13 +00:00
parent d5fc5ca37f
commit ff4f298780
4 changed files with 12 additions and 14 deletions
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16
src/memory.cpp
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@@ -154,8 +154,8 @@ __shared_weak_count::__get_deleter(const type_info&) const _NOEXCEPT
#if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
static const std::size_t __sp_mut_count = 16;
static __libcpp_mutex_t mut_back_imp[__sp_mut_count] =
_LIBCPP_SAFE_STATIC static const std::size_t __sp_mut_count = 16;
_LIBCPP_SAFE_STATIC static __libcpp_mutex_t mut_back[__sp_mut_count] =
{
_LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
_LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
@@ -163,8 +163,6 @@ static __libcpp_mutex_t mut_back_imp[__sp_mut_count] =
_LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER
};
static mutex* mut_back = reinterpret_cast<std::mutex*>(mut_back_imp);
_LIBCPP_CONSTEXPR __sp_mut::__sp_mut(void* p) _NOEXCEPT
: __lx(p)
{
@@ -173,13 +171,13 @@ _LIBCPP_CONSTEXPR __sp_mut::__sp_mut(void* p) _NOEXCEPT
void
__sp_mut::lock() _NOEXCEPT
{
mutex& m = *static_cast<mutex*>(__lx);
auto m = static_cast<__libcpp_mutex_t*>(__lx);
unsigned count = 0;
while (!m.try_lock())
while (__libcpp_mutex_trylock(m) != 0)
{
if (++count > 16)
{
m.lock();
__libcpp_mutex_lock(m);
break;
}
this_thread::yield();
@@ -189,13 +187,13 @@ __sp_mut::lock() _NOEXCEPT
void
__sp_mut::unlock() _NOEXCEPT
{
static_cast<mutex*>(__lx)->unlock();
__libcpp_mutex_unlock(static_cast<__libcpp_mutex_t*>(__lx));
}
__sp_mut&
__get_sp_mut(const void* p)
{
static __sp_mut muts[__sp_mut_count]
static __sp_mut muts[__sp_mut_count]
{
&mut_back[ 0], &mut_back[ 1], &mut_back[ 2], &mut_back[ 3],
&mut_back[ 4], &mut_back[ 5], &mut_back[ 6], &mut_back[ 7],