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Message-ID: <1092975a1cdc4f1bd357d5499540faf755b65854.camel@xry111.site>
Subject: Re: [PATCH v1 4/4] LoongArch: Add tests for Loongson SX
 floating-point conversion instructions.
From: Xi Ruoyao <xry111@xry111.site>
To: Xiaolong Chen <chenxiaolong@loongson.cn>, gcc-patches@gcc.gnu.org
Cc: i@xen0n.name, xuchenghua@loongson.cn, chenglulu@loongson.cn
Date: Wed, 06 Sep 2023 18:56:05 +0800
In-Reply-To: <20230906104537.51583-1-chenxiaolong@loongson.cn>
References: <20230906104537.51583-1-chenxiaolong@loongson.cn>
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On Wed, 2023-09-06 at 18:45 +0800, Xiaolong Chen wrote:
> +=C2=A0 *((int*)& __m128_op0[3]) =3D 0x004200a0;
> +=C2=A0 *((int*)& __m128_op0[2]) =3D 0x00000000;
> +=C2=A0 *((int*)& __m128_op0[1]) =3D 0x004200a0;
> +=C2=A0 *((int*)& __m128_op0[0]) =3D 0x00200001;

These are aliasing rule violation and they will suddenly blow up when
GCC optimizer starts to optimize more aggressively based on the aliasing
rule.

Try not to use these (you can write a helper function to memcpy() into a
__m128).  Or use -fno-strict-alising in dg-options.

--=20
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University