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Re: [PATCH, i386] Add prefixes avoidance tuning for silvermont target
- From: Uros Bizjak <ubizjak at gmail dot com>
- To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Cc: ÐÐÑÑ ÐÐÐÐÐÐÑ <enkovich dot gnu at gmail dot com>, Andi Kleen <andi at firstfloor dot org>, Vladimir Makarov <vmakarov at redhat dot com>, Jakub Jelinek <jakub at redhat dot com>
- Date: Thu, 3 Jul 2014 13:24:27 +0200
- Subject: Re: [PATCH, i386] Add prefixes avoidance tuning for silvermont target
- Authentication-results: sourceware.org; auth=none
Hello!
>> There is already a higher priority for registers not requiring REX.
>> My patch affects cases when compiler has to use xmm8-15 and it just
>> tries to say LRA to assign them for non SSE4 instructions. I doubt it
>> would have some use for other targets than Silvermont.
>
> When it is just a hint, shouldn't there be something like Ya,???x
> or Ya,!x or similar in the SSE4 constraints? I mean, xmm{8-15} can be used,
> just is costly.
Maybe we can use "Ya*x", similar to *pushdf pattern, where it is
costly - but tolerable - to push DFmode value through integer
registers.
Oh, and I didn't notice that Ya name is already taken...
Uros.