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From: Yujie Yang <yangyujie@loongson.cn>
To: Xi Ruoyao <xry111@xry111.site>
Cc: gcc-patches@gcc.gnu.org, WANG Xuerui <i@xen0n.name>,
	Lulu Cheng <chenglulu@loongson.cn>,
	Chenghua Xu <xuchenghua@loongson.cn>
Subject: Re: [PATCH] LoongArch: Stop -mfpu from silently breaking ABI
Date: Fri, 3 Mar 2023 10:12:31 +0800	[thread overview]
Message-ID: <20230303021231.fcvwqvivd6xa2xrn@loongson-pc> (raw)
In-Reply-To: <20230302160122.47573-1-xry111@xry111.site>

On Fri, Mar 03, 2023 at 12:01:22AM +0800, Xi Ruoyao via Gcc-patches wrote:
> But then it causes "-mabi=lp64s -march=loongarch64" to generate code like:
> 
>   movgr2fr.d $fa0, $a0
>   frecip.d   $fa0, $fa0
>   movfr2gr.d $a0, $fa0
> 
> The problem here is "loongarch64" is never strictly defined.  So we
> consider "loongarch64" a "64-bit LoongArch CPU with the simplest FPU
> needed by the ABI", and if -march=loongarch64 but -mfpu is not
> explicitly used, we set -mfpu such a simplest one.

Thanks for the fix on TARGET_*_FLOAT_ABI usage! Certainly more testing
needs to be done on the soft-float side.

However, "loongarch64" is defined to include the "fpu64" ISA module[1]
(i.e. enable "-mfpu=64" when -mfpu is not explicitly used). So I believe
the above behavior you observed is expected.

[1] Table 5. Target CPU Models,
https://loongson.github.io/LoongArch-Documentation/LoongArch-toolchain-conventions-EN.html


  reply	other threads:[~2023-03-03  2:12 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-02 16:01 Xi Ruoyao
2023-03-03  2:12 ` Yujie Yang [this message]
2023-03-03  4:06   ` Xi Ruoyao

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