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From: Kito Cheng <kito.cheng@sifive.com>
To: Joseph Myers <joseph@codesourcery.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>,
	Kito Cheng <kito.cheng@gmail.com>,
	 Jim Wilson <jim.wilson.gcc@gmail.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Andrew Waterman <andrew@sifive.com>,
	"juzhe.zhong" <juzhe.zhong@rivai.ai>
Subject: Re: [PATCH 1/2] RISC-V: Support _Float16 type.
Date: Wed, 27 Jul 2022 17:34:35 +0800	[thread overview]
Message-ID: <CALLt3ThU1oos0rCVUYnAyEVJ4JqCCoa=OadTyBr+BJe7HjfCjQ@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2207262138470.480542@digraph.polyomino.org.uk>

Hi Joseph:

On Wed, Jul 27, 2022 at 5:42 AM Joseph Myers <joseph@codesourcery.com> wrote:
>
> On Thu, 7 Jul 2022, Kito Cheng wrote:
>
> > +/* Implement TARGET_MANGLE_TYPE.  */
> > +
> > +static const char *
> > +riscv_mangle_type (const_tree type)
> > +{
> > +  /* Half-precision float.  */
> > +  if (TREE_CODE (type) == REAL_TYPE && TYPE_PRECISION (type) == 16)
> > +    return "Dh";
>
> Are you sure you wish to use "Dh" instead of "DF16_" used on x86?  The C++
> ABI lists both
>
>                  ::= Dh # IEEE 754r half-precision floating point (16 bits)
>                  ::= DF <number> _ # ISO/IEC TS 18661 binary floating point type _FloatN (N bits)
>
> without distinguishing which should be used when - maybe the choice made
> for _Float16 on RISC-V needs documenting in the RISC-V psABI?

Oh, thanks for catching this, we intend to use DF16_, the patch comes
from downstream which used __fp16 before, but we decided to use
_Float16 as RISC-V official half-precision floating point later.


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

  reply	other threads:[~2022-07-27  9:34 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-07  8:52 [PATCH 0/0] RISC-V: Support IEEE half precision operation Kito Cheng
2022-07-07  8:52 ` [PATCH 1/2] RISC-V: Support _Float16 type Kito Cheng
2022-07-26 21:42   ` Joseph Myers
2022-07-27  9:34     ` Kito Cheng [this message]
2022-07-07  8:52 ` [PATCH 2/2] RISC-V: Support zfh and zfhmin extension Kito Cheng

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