From: Jeff Law <jeffreyalaw@gmail.com>
To: Xi Ruoyao <xry111@xry111.site>, gcc-patches@gcc.gnu.org
Cc: Jakub Jelinek <jakub@redhat.com>,
chenglulu <chenglulu@loongson.cn>,
i@xen0n.name, xuchenghua@loongson.cn, c@jia.je
Subject: Re: [PATCH] middle-end: Call negate_rtx instead of simplify_gen_unary expanding rotate shift [PR113033]
Date: Mon, 18 Dec 2023 08:39:43 -0700 [thread overview]
Message-ID: <a4f25faa-4168-4355-b1c4-ed90f3bff3cc@gmail.com> (raw)
In-Reply-To: <20231218134251.1513432-1-xry111@xry111.site>
On 12/18/23 06:42, Xi Ruoyao wrote:
> With simplify_gen_unary we end up with a not fully expanded RTX like
>
> (set (reg:SI 90) (and:SI (neg:SI (reg:SI 80)) (const_int 63)))
>
> Then it will cause an ICE with unrecognizable insn.
>
> gcc/ChangeLog:
>
> PR middle-end/113033
> * expmed.cc (expand_shift_1): When expanding rotate shift, call
> negate_rtx instead of simplify_gen_unary (NEG, ...).
The key difference being that using negate_rtx will go through the
expander which knows how to synthesize negation whereas
simplify_gen_unary will just generate a (neg ...) and assume it matches
something in the backend, right?
If so, this patch is fine for the trunk.
jeff
next prev parent reply other threads:[~2023-12-18 15:39 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-18 13:42 Xi Ruoyao
2023-12-18 15:39 ` Jeff Law [this message]
2023-12-18 16:48 ` Xi Ruoyao
2023-12-18 17:45 ` Jakub Jelinek
2023-12-18 20:01 ` Xi Ruoyao
2023-12-18 20:15 ` Jakub Jelinek
2023-12-18 20:18 ` Xi Ruoyao
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