https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113106
--- Comment #5 from Uroš Bizjak ---
The issue in comment #2 happens in a couple of places when compiling linux
kernel (with named address spaces enabled). However, the issue is not specific
to named AS, I was just more attentive to moves from %g
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113106
--- Comment #4 from Uroš Bizjak ---
(In reply to Richard Biener from comment #3)
> The situation with address-spaces isn't valid as we need to preserve the
> second load because it's volatile. I think we simply refuse to combine
> volatile load
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113106
Richard Biener changed:
What|Removed |Added
CC||rguenth at gcc dot gnu.org
--- Comment
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113106
--- Comment #2 from Uroš Bizjak ---
For reference, the same optimization should be applied with address spaces:
--cut here--
int __seg_gs b;
int bar(void)
{
return *(volatile __seg_gs int *) &b + b;
}
--cut here--
the above testcase current
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113106
--- Comment #1 from Uroš Bizjak ---
Perhaps related,
--cut here--
int a;
int foo(void)
{
return *(volatile int *) &a + *(volatile int *) &a;
}
--cut here--
compiles with -O2 to:
movla(%rip), %eax
movla(%rip), %edx
