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opal_atomic_rmb: GCC has fixed its acquire fence barrier in its 8 release #10118

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Mar 21, 2022
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opal_atomic_rmb: GCC has fixed its acquire fence barrier in its 8 release #10118

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7 changes: 5 additions & 2 deletions opal/include/opal/sys/atomic_stdc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -50,10 +50,13 @@ static inline void opal_atomic_wmb(void)

static inline void opal_atomic_rmb(void)
{
# if defined(PLATFORM_ARCH_X86_64)
# if defined(PLATFORM_ARCH_X86_64) && PLATFORM_COMPILER_GNU && __GNUC__ < 8
/* work around a bug in older gcc versions (observed in gcc 6.x)
* where acquire seems to get treated as a no-op instead of being
* equivalent to __asm__ __volatile__("": : :"memory") on x86_64 */
* equivalent to __asm__ __volatile__("": : :"memory") on x86_64.
* The issue has been fixed in the GCC 8 release series:
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80640
*/
opal_atomic_mb();
# else
atomic_thread_fence(memory_order_acquire);
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