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Re: [PATCH] Improve andq $0xffffffff, %reg handling (PR target/53110)
- From: Uros Bizjak <ubizjak at gmail dot com>
- To: Teresa Johnson <tejohnson at google dot com>
- Cc: Jakub Jelinek <jakub at redhat dot com>, Richard Henderson <rth at redhat dot com>, gcc-patches at gcc dot gnu dot org, David Li <davidxl at google dot com>
- Date: Tue, 24 Jul 2012 12:18:47 +0200
- Subject: Re: [PATCH] Improve andq $0xffffffff, %reg handling (PR target/53110)
- References: <20120425191453.GX16117@tyan-ft48-01.lab.bos.redhat.com> <CAFULd4Zf6MSEmY_jF5ppWBY+Wz5Jwou3w-kS1jGdEXpwNxubcg@mail.gmail.com> <20120426152814.GB16117@tyan-ft48-01.lab.bos.redhat.com> <CAFULd4ZKBD_OzR7DFT2RogTW8B4gavRXbgxXs44i-X2viz-5HQ@mail.gmail.com> <CAFULd4aXx3Lbweow+5FoFeHA-3ud2r-6ckz7XEzK3jWazvG18A@mail.gmail.com> <20120430131009.GK16117@tyan-ft48-01.lab.bos.redhat.com> <CAFULd4ZEe1WW2cgd7_ENoF-BviuOH65ArX1nFqP9e0SyxiQs3w@mail.gmail.com> <CAAe5K+V=fycJ5Fxc0i=SHtfmhtYdETfYjjA6UzFe=15YiCbQhA@mail.gmail.com> <CAAe5K+UwKp-qO4+YxHKmNfyBFOXqEJ_8Z6qtdQkMQ8gcnig0iw@mail.gmail.com>
On Mon, Jul 23, 2012 at 10:17 PM, Teresa Johnson <tejohnson@google.com> wrote:
> Resending in plain text mode so it goes through.
> Teresa
>
> On Mon, Jul 23, 2012 at 12:03 PM, Teresa Johnson <tejohnson@google.com> wrote:
>> Any possibility of getting these patches (186979 and 186993), along with
>> r184891 (which added the and->zext splitter), backported to the 4_7 branch?
>> I found a performance issue where "andw $0xff, %reg" was not being converted
>> to movzbl when the source and target registers are the same, resulting in
>> LCP stalls, which is fixed by this series of patches.
These looks too risky, especially r184891. I have waited with this
patch after 4.7 branched just because of this risk factor.
BTW: This part was wrong, there is no xmm->xmm movq insn:
(*zero_extendsidi2_rex64): Add x,x alternative.
(*zero_extendsidi2): Ditto.
Uros.