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From: "crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/102566] [i386] GCC should emit LOCK BTS for simple bit-test-and-set operations with std::atomic Date: Fri, 22 Oct 2021 03:31:05 +0000 [thread overview] Message-ID: <bug-102566-4-RvFhZG3L0P@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-102566-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102566 --- Comment #28 from Hongtao.liu <crazylht at gmail dot com> --- Can be optimize int gomp_futex_wake = FUTEX_WAKE | FUTEX_PRIVATE_FLAG; int gomp_futex_wait = FUTEX_WAIT | FUTEX_PRIVATE_FLAG; void gomp_mutex_lock_slow (gomp_mutex_t *mutex, int oldval) { /* First loop spins a while. */ while (oldval == 1) { if (do_spin (mutex, 1)) { /* Spin timeout, nothing changed. Set waiting flag. */ oldval = __atomic_exchange_n (mutex, -1, MEMMODEL_ACQUIRE); if (oldval == 0) return; futex_wait (mutex, -1); break; } else { /* Something changed. If now unlocked, we're good to go. */ oldval = 0; if (__atomic_compare_exchange_n (mutex, &oldval, 1, false, MEMMODEL_ACQUIRE, MEMMODEL_RELAXED)) return; } } /* Second loop waits until mutex is unlocked. We always exit this loop with wait flag set, so next unlock will awaken a thread. */ while ((oldval = __atomic_exchange_n (mutex, -1, MEMMODEL_ACQUIRE))) do_wait (mutex, -1); } with _atomic_fetch_or/and/xor ?
next prev parent reply other threads:[~2021-10-22 3:31 UTC|newest] Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-02 16:08 [Bug target/102566] New: " thiago at kde dot org 2021-10-02 20:30 ` [Bug target/102566] " pinskia at gcc dot gnu.org 2021-10-03 12:56 ` hjl.tools at gmail dot com 2021-10-03 13:06 ` hjl.tools at gmail dot com 2021-10-03 13:19 ` [Bug tree-optimization/102566] " hjl.tools at gmail dot com 2021-10-03 15:10 ` hjl.tools at gmail dot com 2021-10-03 16:45 ` [Bug middle-end/102566] " hjl.tools at gmail dot com 2021-10-03 22:36 ` hjl.tools at gmail dot com 2021-10-04 15:58 ` thiago at kde dot org 2021-10-04 16:10 ` thiago at kde dot org 2021-10-04 16:13 ` thiago at kde dot org 2021-10-04 21:46 ` hjl.tools at gmail dot com 2021-10-04 23:25 ` thiago at kde dot org 2021-10-04 23:26 ` thiago at kde dot org 2021-10-05 4:40 ` hjl.tools at gmail dot com 2021-10-05 15:23 ` hjl.tools at gmail dot com 2021-10-05 15:57 ` thiago at kde dot org 2021-10-05 16:02 ` pinskia at gcc dot gnu.org 2021-10-05 19:26 ` hjl.tools at gmail dot com 2021-10-05 19:30 ` hjl.tools at gmail dot com 2021-10-05 19:36 ` thiago at kde dot org 2021-10-06 8:00 ` jakub at gcc dot gnu.org 2021-10-06 15:40 ` thiago at kde dot org 2021-10-06 15:47 ` hjl.tools at gmail dot com 2021-10-06 15:54 ` thiago at kde dot org 2021-10-06 16:05 ` hjl.tools at gmail dot com 2021-10-07 15:18 ` thiago at kde dot org 2021-10-07 15:19 ` hjl.tools at gmail dot com 2021-10-07 15:35 ` thiago at kde dot org 2021-10-10 13:51 ` hjl.tools at gmail dot com 2021-10-22 3:31 ` crazylht at gmail dot com [this message] 2021-11-04 21:24 ` thiago at kde dot org 2021-11-10 9:17 ` cvs-commit at gcc dot gnu.org 2022-10-29 10:53 ` marko.makela at mariadb dot com 2022-10-31 2:42 ` crazylht at gmail dot com 2022-11-01 8:41 ` marko.makela at mariadb dot com 2022-11-01 16:46 ` hjl.tools at gmail dot com 2022-11-07 19:20 ` cvs-commit at gcc dot gnu.org 2023-01-18 18:49 ` hjl.tools at gmail dot com 2023-01-18 22:30 ` hjl.tools at gmail dot com
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