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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.

  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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