https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
Richard Biener changed:
What|Removed |Added
Target Milestone|12.5|---
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
Richard Biener changed:
What|Removed |Added
Target Milestone|12.4|12.5
--- Comment #25 from Richard Bien
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
Richard Biener changed:
What|Removed |Added
Target Milestone|12.3|12.4
--- Comment #24 from Richard Bien
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
Richard Biener changed:
What|Removed |Added
Target Milestone|12.2|12.3
--- Comment #23 from Richard Bien
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
Jakub Jelinek changed:
What|Removed |Added
Target Milestone|12.0|12.2
--- Comment #22 from Jakub Jelinek
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #21 from CVS Commits ---
The master branch has been updated by Hongyu Wang :
https://gcc.gnu.org/g:522f25e90c781d284f8347a04940db8b41c42fd5
commit r12-8136-g522f25e90c781d284f8347a04940db8b41c42fd5
Author: Hongyu Wang
Date: Wed
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #20 from Thiago Macieira ---
I think there will be cases where the relaxation makes sense and others where
it doesn't because the surrounding code already does it. So I'd like to control
per emission.
If I can't do it per code block
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #19 from Hongyu Wang ---
(In reply to Thiago Macieira from comment #18)
> (In reply to Jakub Jelinek from comment #17)
> > _Pragma("GCC target \"relax-cmpxchg-loop\"")
> > should do that (ditto target("relax-cmpxchg-loop") attribute)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #18 from Thiago Macieira ---
(In reply to Jakub Jelinek from comment #17)
> _Pragma("GCC target \"relax-cmpxchg-loop\"")
> should do that (ditto target("relax-cmpxchg-loop") attribute).
The attribute is applied to a function. I'm ho
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
Jakub Jelinek changed:
What|Removed |Added
CC||jakub at gcc dot gnu.org
--- Comment #1
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #16 from Thiago Macieira ---
Can this option be enabled and disabled with a _Pragma?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #15 from Hongyu Wang ---
(In reply to Thiago Macieira from comment #14)
> I'd restrict relaxations to loops emitted by the compiler. All other atomic
> operations shouldn't be modified at all, unless the user asks for it. That
> incl
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #14 from Thiago Macieira ---
I'd restrict relaxations to loops emitted by the compiler. All other atomic
operations shouldn't be modified at all, unless the user asks for it. That
includes non-looping atomic operations (like LOCK BTC
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #13 from Hongyu Wang ---
All above glibc cases are now both relaxed by an load/cmp to skip cmpxchg under
-mrelax-cmpxchg-loop,
but for
> do
> {
> flags = THREAD_GETMEM (self, cancelhandling);
> newval = THREA
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #12 from CVS Commits ---
The master branch has been updated by Hongyu Wang :
https://gcc.gnu.org/g:0435b978f95971e139882549f5a1765c50682216
commit r12-7316-g0435b978f95971e139882549f5a1765c50682216
Author: Hongyu Wang
Date: Fri
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #11 from Hongyu Wang ---
For the case with atomic_compare_exchange_weak_release, it can be expanded as
loop: mov%eax,%r8d
and$0xfff8,%r8d
mov(%r8),%rsi <--- load lock first
cmp%rsi,%rax <--- c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #10 from Thiago Macieira ---
(In reply to H.J. Lu from comment #9)
> nptl/nptl_setxid.c in glibc has
>
> do
> {
> flags = THREAD_GETMEM (self, cancelhandling);
> newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cance
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
H.J. Lu changed:
What|Removed |Added
Status|REOPENED|NEW
--- Comment #9 from H.J. Lu ---
nptl/npt
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #8 from H.J. Lu ---
nptl/pthread_create.c has
do
pd->nextevent = __nptl_last_event;
while (atomic_compare_and_exchange_bool_acq (&__nptl_last_event,
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #7 from H.J. Lu ---
nptl/pthread_mutex_unlock.c in glibc has:
do
{
newval = oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK;
}
while (!atomic_compare_exchange_weak_release (&mutex->__data.__lock,
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
H.J. Lu changed:
What|Removed |Added
Status|RESOLVED|REOPENED
Ever confirmed|0
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #5 from CVS Commits ---
The master branch has been updated by Hongyu Wang :
https://gcc.gnu.org/g:15f5e70cbb33b40c97325ef9d7747a148d39
commit r12-5363-g15f5e70cbb33b40c97325ef9d7747a148d39
Author: Hongyu Wang
Date: Thu N
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
H.J. Lu changed:
What|Removed |Added
Status|UNCONFIRMED |RESOLVED
Target Milestone|---
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #3 from CVS Commits ---
The master branch has been updated by Hongyu Wang :
https://gcc.gnu.org/g:4d281ff7ddd8f6365943c0a622107f92315bb8a6
commit r12-5265-g4d281ff7ddd8f6365943c0a622107f92315bb8a6
Author: Hongyu Wang
Date: Fri N
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #2 from Thiago Macieira ---
See also bug 103090 for a few more (restricted) possibilities to replace a
cmpxchg loop with a LOCK RMW operation.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103069
--- Comment #1 from Thiago Macieira ---
(the assembly doesn't match the source code, but we got your point)
Another possible improvement for the __atomic_fetch_{and,nand,or} functions is
that it can check whether the fetched value is already co
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