[cfe-dev] Is force_align_arg_pointer function attribute supported at x86?

[Tim Northover via cfe-dev]

Hi Anatol,

On 21 June 2017 at 13:30, Anatol Pomozov via cfe-dev
<cfe-dev at lists.llvm.org> wrote:
> There is a function
> attribute __attribute__((force_align_arg_pointer)) that works great
> with gcc 7.x.

I think the issue is that this attribute only applies to 32-bit x86
(i.e. compiling with -m32). All x86_64 ABIs require sufficient stack
alignment for SSE instructions so Clang doesn't support it there.

Essential stack realignment probably needs to be done in assembly if
you're writing an OS or equivalent low-level code.

Tim.