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| author | Thomas Rodgers <trodgers@redhat.com> | 2022-07-05 17:42:42 -0700 |
|---|---|---|
| committer | Martin Liska <mliska@suse.cz> | 2022-07-28 14:09:03 +0200 |
| commit | f0b75c239b45d7c48b6b9d76a3efa048ae10118b (patch) | |
| tree | 03ae5e850d2791cca1d8571981f0b2c8c3d9e6f8 | |
| parent | 4aa2b803c18542f76d565f77508e8fab12d66feb (diff) | |
| download | gcc-f0b75c239b45d7c48b6b9d76a3efa048ae10118b.zip gcc-f0b75c239b45d7c48b6b9d76a3efa048ae10118b.tar.gz gcc-f0b75c239b45d7c48b6b9d76a3efa048ae10118b.tar.bz2 | |
libstdc++: Minor codegen improvement for atomic wait spinloop
This patch merges the spin loops in the atomic wait implementation which is a
minor codegen improvement.
libstdc++-v3/ChangeLog:
* include/bits/atomic_wait.h (__atomic_spin): Merge spin loops.
| -rw-r--r-- | libstdc++-v3/include/bits/atomic_wait.h | 17 |
1 files changed, 7 insertions, 10 deletions
diff --git a/libstdc++-v3/include/bits/atomic_wait.h b/libstdc++-v3/include/bits/atomic_wait.h index 125b1ca..a6d55d3 100644 --- a/libstdc++-v3/include/bits/atomic_wait.h +++ b/libstdc++-v3/include/bits/atomic_wait.h @@ -142,8 +142,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION #endif } - constexpr auto __atomic_spin_count_1 = 12; - constexpr auto __atomic_spin_count_2 = 4; + constexpr auto __atomic_spin_count_relax = 12; + constexpr auto __atomic_spin_count = 16; struct __default_spin_policy { @@ -157,18 +157,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION bool __atomic_spin(_Pred& __pred, _Spin __spin = _Spin{ }) noexcept { - for (auto __i = 0; __i < __atomic_spin_count_1; ++__i) + for (auto __i = 0; __i < __atomic_spin_count; ++__i) { if (__pred()) return true; - __detail::__thread_relax(); - } - for (auto __i = 0; __i < __atomic_spin_count_2; ++__i) - { - if (__pred()) - return true; - __detail::__thread_yield(); + if (__i < __atomic_spin_count_relax) + __detail::__thread_relax(); + else + __detail::__thread_yield(); } while (__spin()) |