[llvmlinux] ARM Integrated Assembler by default

Renato Golin renato.golin at linaro.org
Tue Dec 10 14:34:15 UTC 2013


On 10 December 2013 14:09, Behan Webster <behanw at converseincode.com> wrote:
> For now we've mostly just used "-no-integrated-as" to narrow down our
> focus of getting the rest working and upstream first.

Hi Behan,

Thanks for you answer, this is exactly what I wanted to know. Turning
on the IAS won't break anything for you guys, as that would be a major
pain, and I'm happy that we can de-couple both progresses.

I just sent an email to turn it on by default, as is the consensus of
most ARM maintainers, and we should be doing this soon. We're opening
bugs in the LLVM bugzilla with all missign support from IAS, so if you
guys know of anything, please report them, feel free to copy me, and
we can check later if we add support in the IAS, or we wait for it to
be fixed in the kernel or GCC.


> The simplest thing to say is that IA on the ARM side doesn't support
> non-unified ARM ASM format, nor the many GNU extensions used in the
> kernel code

Yes, I know. And as you said later, it's not just syntax, it's the
unwritten contract that gets as low as emitting spurious data
barriers, which is quite serious, I think.

If they have to access the stack to emit a data memory barrier, than
this seems like a bug in both GCC and kernel, and we should have
enough arguments to fix all three!

Regardless, I agree we should progress independently, but would be
very good if you guys could report the known cases, too. I have
already reported the missing command-line options Vinicius found.

Thanks!
--renato


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