From: "H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org>
To: Joseph Myers <joseph@codesourcery.com>
Cc: llvm-dev@lists.llvm.org, GCC Patches <gcc-patches@gcc.gnu.org>,
GNU C Library <libc-alpha@sourceware.org>,
IA32 System V Application Binary Interface
<ia32-abi@googlegroups.com>
Subject: Re: [PATCH] Add optional _Float16 support
Date: Thu, 1 Jul 2021 15:27:37 -0700 [thread overview]
Message-ID: <CAMe9rOo8vgANgSuxJjvt5A98TL9Hz1SQc7mk3gDnz7gX=Uk+KA@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2107012202060.419529@digraph.polyomino.org.uk>
On Thu, Jul 1, 2021 at 3:10 PM Joseph Myers <joseph@codesourcery.com> wrote:
>
> On Thu, 1 Jul 2021, H.J. Lu via Gcc-patches wrote:
>
> > 2. Return _Float16 and _Complex _Float16 values in %xmm0/%xmm1 registers.
>
> That restricts use of _Float16 to processors with SSE. Is that what we
> want in the ABI, or should _Float16 be available with base 32-bit x86
> architecture features only, much like _Float128 and the decimal FP types
Yes, _Float16 requires XMM registers.
> are? (If it is restricted to SSE, we can of course ensure relevant libgcc
> functions are built with SSE enabled, and likewise in glibc if that gains
> _Float16 functions, though maybe with some extra complications to get
> relevant testcases to run whenever possible.)
>
_Float16 functions in libgcc should be compiled with SSE enabled.
BTW, _Float16 software emulation may require more than just SSE
since we need to do _Float16 load and store with XMM registers.
There is no 16bit load/store for XMM registers without AVX512FP16.
--
H.J.
next prev parent reply other threads:[~2021-07-01 22:28 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-01 21:05 [PATCH] Add optional _Float16 support H.J. Lu via Libc-alpha
2021-07-01 22:10 ` Joseph Myers
2021-07-01 22:27 ` H.J. Lu via Libc-alpha [this message]
2021-07-01 22:40 ` Joseph Myers
2021-07-01 23:01 ` H.J. Lu via Libc-alpha
2021-07-01 23:05 ` [llvm-dev] " Craig Topper via Libc-alpha
2021-07-01 23:33 ` Jacob Lifshay via Libc-alpha
2021-07-02 7:45 ` Richard Biener via Libc-alpha
2021-07-02 8:03 ` Hongtao Liu via Libc-alpha
2021-07-02 9:21 ` Jakub Jelinek via Libc-alpha
2021-07-13 3:59 ` Wang, Pengfei via Libc-alpha
2021-07-13 14:26 ` H.J. Lu via Libc-alpha
2021-07-13 14:48 ` Wang, Pengfei via Libc-alpha
2021-07-13 15:04 ` H.J. Lu via Libc-alpha
2021-07-13 15:41 ` Joseph Myers
2021-07-13 16:24 ` H.J. Lu via Libc-alpha
2021-07-29 13:39 ` H.J. Lu via Libc-alpha
2021-08-24 5:55 ` John McCall via Libc-alpha
2021-08-25 12:35 ` H.J. Lu via Libc-alpha
2021-08-25 20:32 ` John McCall via Libc-alpha
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