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[PATCH, i386]: Fix PR77270, Flag -mprftchw is shared with 3dnow for -march=k8

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>
Date: Fri, 19 Aug 2016 20:20:32 +0200
Subject: [PATCH, i386]: Fix PR77270, Flag -mprftchw is shared with 3dnow for -march=k8
Authentication-results: sourceware.org; auth=none

Hello!

There is a problem with -march=native, when -m3dnow and -mno-prfchw
are added to the compilation flags. The prefetchw is enabled by
-m3dnow, but TARGET_PRFCHW is never enabled, since explicit
-mno-prfchw is passed by the driver.

Attached patch fixes this by divorcing TARGET_3DNOW from TARGET_PRFCHW.

2016-08-19  Uros Bizjak  <ubizjak@gmail.com>

    PR target/77270
    * config/i386/i386.c (ix86_option_override_internal): Remove
    PTA_PRFCHW from entries that also have PTA_3DNOW flag.
    Enable SSE prefetch also for TARGET_PREFETCHWT1.
    Do not try to enable TARGET_PRFCHW ISA flag here.
    * config/i386/i386.md (prefetch): Enable also for TARGET_3DNOW.
    Rewrite expander function body.
    (*prefetch_3dnow): Enable for TARGET_3DNOW and TARGET_PREFETCHWT1.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

Committed to mainline, I plan to backport the patch to gcc-6 branch,
once it opens.

Uros.

Attachment: p.diff.txt
Description: Text document

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