[llvm] r247450 - Use function attribute "stackrealign" to decide whether stack

[Reid Kleckner via llvm-commits]

On Fri, Sep 11, 2015 at 3:30 PM, Hal Finkel <hfinkel at anl.gov> wrote:

> ----- Original Message -----
> > From: "Reid Kleckner via llvm-commits" <llvm-commits at lists.llvm.org>
> > To: "Akira Hatanaka" <ahatanak at gmail.com>
> > Cc: "llvm-commits" <llvm-commits at lists.llvm.org>
> > Sent: Friday, September 11, 2015 5:08:38 PM
> > Subject: Re: [llvm] r247450 - Use function attribute "stackrealign" to
> decide whether stack
> >
> >
> >
> > I recall some users from nvidia or Intel did something like arranging
> > to call a function using AVX with 32-byte stack alignment, and using
> > -mno-stackrealign to suppress the funky prologue. They would
> > probably be better served with an ABI stack alignment override, so
> > maybe that use case is not worth considering.
> >
>
> It seems like, for this use case, we really want an attribute to specify
> what the enhanced caller-provided stack alignment actually is, so that the
> backend can then make the appropriate choice about generating a stack
> realignment based on the needs of its local variables and spill slots.
>

Precisely. Actually, don't we already have an attribute for this? Isn't
"stackrealign" equivalent to alignstack(1)?
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