[llvm-dev] [PATCH] Add optional _Float16 support (original) (raw)
John McCall via llvm-dev llvm-dev at lists.llvm.org
Wed Aug 25 13:32:52 PDT 2021
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On Wed, Aug 25, 2021 at 8:36 AM H.J. Lu <hjl.tools at gmail.com> wrote:
On Mon, Aug 23, 2021 at 10:55 PM John McCall <rjmccall at gmail.com> wrote: > On Thu, Jul 29, 2021 at 9:40 AM H.J. Lu <hjl.tools at gmail.com> wrote: >> On Tue, Jul 13, 2021 at 9:24 AM H.J. Lu <hjl.tools at gmail.com> wrote: >> > 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. >> >> Here is the final patch I checked in. Complex Float16 is changed to return >> in XMM0 register. The new PDF file is at >> >> https://gitlab.com/x86-psABIs/i386-ABI/-/wikis/Intel386-psABI > > > This should be explicit that the real part is returned in bits 0..15 and the imaginary part is returned in bits 16..31, or however we conventionally designate subcomponents of a vector.
How about this? diff --git a/low-level-sys-info.tex b/low-level-sys-info.tex index 860ff66..8f527c1 100644 --- a/low-level-sys-info.tex +++ b/low-level-sys-info.tex @@ -457,6 +457,9 @@ and \texttt{unions}) are always returned in memory. _& \texttt{float128} & memory \ \hline & \texttt{Complex Float16} & \reg{xmm0} \ + & & The real part is returned in bits 0..15. The imaginary part is + returned \ + & & in bits 16..31.\ \cline{2-3} Complex & \texttt{Complex float} & \EDX:\EAX \ floating- & & The real part is returned in \EAX. The imaginary part is
Looks good to me, thanks.
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