[llvm-dev] [PATCH] Add optional _Float16 support

H.J. Lu via llvm-dev llvm-dev at lists.llvm.org
Tue Jul 13 09:24:14 PDT 2021


On Tue, Jul 13, 2021 at 8:41 AM Joseph Myers <joseph at codesourcery.com> wrote:
>
> On Tue, 13 Jul 2021, H.J. Lu wrote:
>
> > On Mon, Jul 12, 2021 at 8:59 PM Wang, Pengfei <pengfei.wang at intel.com> wrote:
> > >
> > > > Return _Float16 and _Complex _Float16 values in %xmm0/%xmm1 registers.
> > >
> > > Can you please explain the behavior here? Is there difference between _Float16 and _Complex _Float16 when return? I.e.,
> > > 1, In which case will _Float16 values return in both %xmm0 and %xmm1?
> > > 2, For a single _Float16 value, are both real part and imaginary part returned in %xmm0? Or returned in %xmm0 and %xmm1 respectively?
> >
> > Here is the v2 patch to add the missing _Float16 bits.   The PDF file is at
> >
> > https://gitlab.com/x86-psABIs/i386-ABI/-/wikis/Intel386-psABI
>
> This PDF shows _Complex _Float16 as having a size of 2 bytes (should be
> 4-byte size, 2-byte alignment).
>
> It also seems to change double from 4-byte to 8-byte alignment, which is
> wrong.  And it's inconsistent about whether it covers the long double =
> double (Android) case - it shows that case for _Complex long double but
> not for long double itself.

Here is the v3 patch with the fixes.  I also updated the PDF file.

> --
> Joseph S. Myers
> joseph at codesourcery.com
>


-- 
H.J.
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