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| author | Jonathan Wakely <jwakely@redhat.com> | 2020-11-24 12:29:30 +0000 |
|---|---|---|
| committer | Jonathan Wakely <jwakely@redhat.com> | 2020-11-24 14:59:40 +0000 |
| commit | e253d36214015ed10ffd335e3628ccaac22dd5c7 (patch) | |
| tree | 92f4310a31283e95f47fdb77b241ad79641518af /libstdc++-v3/src | |
| parent | 97981e13b7f7b1ffd1c9ccf3d96d574b7b3caada (diff) | |
| download | gcc-e253d36214015ed10ffd335e3628ccaac22dd5c7.zip gcc-e253d36214015ed10ffd335e3628ccaac22dd5c7.tar.gz gcc-e253d36214015ed10ffd335e3628ccaac22dd5c7.tar.bz2 | |
libstdc++: Use __libc_single_threaded for locale initialization
Most initialization of locales and facets happens before main() during
startup, when the program is likely to only have one thread. By using
the new __gnu_cxx::__is_single_threaded() function instead of checking
__gthread_active_p() we can avoid using pthread_once or atomics for the
common case.
That said, I'm not sure why we don't just use a local static variable
instead, as __cxa_guard_acquire() already optimizes for the
single-threaded case:
static const bool init = (_S_initialize_once(), true);
I'll revisit that for GCC 12.
libstdc++-v3/ChangeLog:
* src/c++98/locale.cc (locale::facet::_S_get_c_locale())
(locale::id::_M_id() const): Use __is_single_threaded.
* src/c++98/locale_init.cc (locale::_S_initialize()):
Likewise.
Diffstat (limited to 'libstdc++-v3/src')
| -rw-r--r-- | libstdc++-v3/src/c++98/locale.cc | 4 | ||||
| -rw-r--r-- | libstdc++-v3/src/c++98/locale_init.cc | 2 |
2 files changed, 3 insertions, 3 deletions
diff --git a/libstdc++-v3/src/c++98/locale.cc b/libstdc++-v3/src/c++98/locale.cc index 0642241..9b3fc35 100644 --- a/libstdc++-v3/src/c++98/locale.cc +++ b/libstdc++-v3/src/c++98/locale.cc @@ -214,7 +214,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION locale::facet::_S_get_c_locale() { #ifdef __GTHREADS - if (__gthread_active_p()) + if (!__gnu_cxx::__is_single_threaded()) __gthread_once(&_S_once, _S_initialize_once); else #endif @@ -515,7 +515,7 @@ namespace { #endif #ifdef __GTHREADS - if (__gthread_active_p()) + if (!__gnu_cxx::__is_single_threaded()) { if (__atomic_always_lock_free(sizeof(_M_index), &_M_index)) { diff --git a/libstdc++-v3/src/c++98/locale_init.cc b/libstdc++-v3/src/c++98/locale_init.cc index c3841cc..fc8416b 100644 --- a/libstdc++-v3/src/c++98/locale_init.cc +++ b/libstdc++-v3/src/c++98/locale_init.cc @@ -320,7 +320,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION locale::_S_initialize() { #ifdef __GTHREADS - if (__gthread_active_p()) + if (!__gnu_cxx::__is_single_threaded()) __gthread_once(&_S_once, _S_initialize_once); #endif if (!_S_classic) |