From: Max Filippov <jcmvbkbc@gmail.com>
To: "Takayuki 'January June' Suwa" <jjsuwa_sys3175@yahoo.co.jp>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] xtensa: Optimize boolean evaluation when SImode EQ/NE to zero if TARGET_MINMAX
Date: Wed, 6 Sep 2023 03:26:23 -0700 [thread overview]
Message-ID: <CAMo8BfL71yfykkMrqoHTb5XKgjop-jtyzHPhD=EjuWHFbZ4NkQ@mail.gmail.com> (raw)
In-Reply-To: <8888cd4e-8168-5065-af35-5096aa24f37f@yahoo.co.jp>
On Tue, Sep 5, 2023 at 9:24 PM Takayuki 'January June' Suwa
<jjsuwa_sys3175@yahoo.co.jp> wrote:
> On 2023/09/06 8:01, Max Filippov wrote:
> > On Tue, Sep 5, 2023 at 2:29 AM Takayuki 'January June' Suwa
> > <jjsuwa_sys3175@yahoo.co.jp> wrote:
> >> ;; after (prereq. TARGET_MINMAX)
> >> test0:
> >> movi.n a9, 1
> >> minu a2, a2, a9
> >> xor a2, a2, a9
> >> ret.n
> >
> > ISTM that test0 could be done with movnez in the same three instructions:
> >
> > movi a9, 1
> > movnez a2, a9, a2
> > xor a2, a2, a9
>
> Unfortunately, the MOV[EQ/NE]Z machine instruction can only be used
> to implement the functionality if the input and output physical registers
> are the same (a2 in the example).
Oh yeah, you're right, I missed that.
--
Thanks.
-- Max
next prev parent reply other threads:[~2023-09-06 10:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <0164dc5a-35a7-2848-8153-5016f7582576.ref@yahoo.co.jp>
2023-09-05 9:27 ` Takayuki 'January June' Suwa
2023-09-05 23:01 ` Max Filippov
2023-09-06 4:24 ` Takayuki 'January June' Suwa
2023-09-06 10:26 ` Max Filippov [this message]
2023-09-06 10:27 ` Max Filippov
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