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* [Bug target/39677] AMD Opteron E needs workaround for lock erratum [not found] <bug-39677-4@http.gcc.gnu.org/bugzilla/> @ 2021-07-19 18:28 ` pinskia at gcc dot gnu.org 0 siblings, 0 replies; 3+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-07-19 18:28 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=39677 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution|--- |INVALID --- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> --- So reading https://www.amd.com/system/files/TechDocs/25759.pdf and errata #147, the errata only occurs if lock is not there: The erratum will not occur if there is a LOCK prefix on the read-modify-write instruction. And GCC never emits a cmpxchg without a lock prefix so there is nothing to be done. ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug middle-end/39677] New: AMD Opteron E needs workaround for lock erratum
@ 2009-04-07 13:36 bonzini at gnu dot org
2009-10-13 1:07 ` [Bug target/39677] " rth at gcc dot gnu dot org
2009-12-07 16:12 ` rth at gcc dot gnu dot org
0 siblings, 2 replies; 3+ messages in thread
From: bonzini at gnu dot org @ 2009-04-07 13:36 UTC (permalink / raw)
To: gcc-bugs
From
http://code.google.com/p/google-perftools/source/browse/trunk/src/base/atomicops-internals-x86.h
bool has_amd_lock_mb_bug; // Processor has AMD memory-barrier bug; do lfence
// after acquire compare-and-swap.
...
inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
Atomic32 old_value,
Atomic32 new_value) {
Atomic32 prev;
__asm__ __volatile__("lock; cmpxchgl %1,%2"
: "=a" (prev)
: "q" (new_value), "m" (*ptr), "0" (old_value)
: "memory");
return prev;
}
inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
Atomic32 old_value,
Atomic32 new_value) {
Atomic32 x = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
if (AtomicOps_Internalx86CPUFeatures.has_amd_lock_mb_bug) {
__asm__ __volatile__("lfence" : : : "memory");
}
return x;
}
inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
Atomic32 old_value,
Atomic32 new_value) {
return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
}
This bug can also affect lock+xadd combinations.
--
Summary: AMD Opteron E needs workaround for lock erratum
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Keywords: openmp
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: bonzini at gnu dot org
GCC target triplet: i386-*-*, x86_64-*-*
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39677
^ permalink raw reply [flat|nested] 3+ messages in thread* [Bug target/39677] AMD Opteron E needs workaround for lock erratum 2009-04-07 13:36 [Bug middle-end/39677] New: " bonzini at gnu dot org @ 2009-10-13 1:07 ` rth at gcc dot gnu dot org 2009-12-07 16:12 ` rth at gcc dot gnu dot org 1 sibling, 0 replies; 3+ messages in thread From: rth at gcc dot gnu dot org @ 2009-10-13 1:07 UTC (permalink / raw) To: gcc-bugs ------- Comment #3 from rth at gcc dot gnu dot org 2009-10-13 01:07 ------- Not an openmp bug; we've got to make the change for all code gcc generates. -- rth at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- AssignedTo|unassigned at gcc dot gnu |rth at gcc dot gnu dot org |dot org | Status|NEW |ASSIGNED Component|middle-end |target Keywords|openmp | Last reconfirmed|2009-04-07 13:42:25 |2009-10-13 01:07:32 date| | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39677 ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/39677] AMD Opteron E needs workaround for lock erratum 2009-04-07 13:36 [Bug middle-end/39677] New: " bonzini at gnu dot org 2009-10-13 1:07 ` [Bug target/39677] " rth at gcc dot gnu dot org @ 2009-12-07 16:12 ` rth at gcc dot gnu dot org 1 sibling, 0 replies; 3+ messages in thread From: rth at gcc dot gnu dot org @ 2009-12-07 16:12 UTC (permalink / raw) To: gcc-bugs ------- Comment #4 from rth at gcc dot gnu dot org 2009-12-07 16:12 ------- Not working on it any longer. -- rth at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- AssignedTo|rth at gcc dot gnu dot org |unassigned at gcc dot gnu | |dot org Status|ASSIGNED |NEW http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39677 ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-07-19 18:28 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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[not found] <bug-39677-4@http.gcc.gnu.org/bugzilla/>
2021-07-19 18:28 ` [Bug target/39677] AMD Opteron E needs workaround for lock erratum pinskia at gcc dot gnu.org
2009-04-07 13:36 [Bug middle-end/39677] New: " bonzini at gnu dot org
2009-10-13 1:07 ` [Bug target/39677] " rth at gcc dot gnu dot org
2009-12-07 16:12 ` rth at gcc dot gnu dot org
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