On Fri, Aug 28, 2015 at 09:58:46AM -0400, Tom Lane wrote:
> Noah Misch <noah@leadboat.com> writes:
> > On Thu, Aug 27, 2015 at 10:36:46AM -0400, Tom Lane wrote:
> >> So s_lock.h's PowerPC assembly code works if you have gcc configured to
> >> use gas as backend, but not if it's configured to use the native AIX
> >> assembler. Steve says the latter configuration is pretty common.
>
> > These days, the latter configuration is all but universal. Per the GCC
> > installation instructions, "The GNU Assembler has not been updated to support
> > AIX 6 or AIX 7."
>
> Ouch. I'm surprised we've not gotten more complaints.
That surprised me, too. Perhaps almost everyone has used either xlc or that
IBM-provided gcc you wrote about.
> >> 2. Don't rely on local symbols in the PPC spinlock assembly code.
> > A third option is to use __sync intrinsics, like we do on ARM. I like (2).
>
> I've been waiting to hear confirmation from Steve that the proposed patch
> works with IBM's assembler. (For all I know, it uses "*" rather than ".",
> or some other randomness.) He's not responded yet though. Are you in
> a position to test the patch?
I tested a gcc 64-bit build. Consistent with your followup, "b .+12" doesn't
build, but "b $+12" builds and passes "make check". I am attaching the exact
diff I tested.
On GNU/Linux ppc, I get the same opcodes before and after the change.
