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[PATCH, i386]: Remove cmp_*_cc_i387 FP compare patterns

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, 5 Oct 2018 20:54:20 +0200
Subject: [PATCH, i386]: Remove cmp_*_cc_i387 FP compare patterns

These are ineffective, since no pass considers compares inside
PARALLELs. They just weather through all pre-reload passes and then
split to fcom+fnstsw/sahf sequence. We can as well expand compares to
the above sequence at expand time.

2018-10-05  Uros Bizjak  <ubizjak@gmail.com>

    * config/i386/i386.md (*cmpxf_cc_i387): Remove pattern.
    (*cmp<mode>_cc_i387): Ditto.
    (*cmpu<mode>_cc_i387): Ditto.
    (*cmp<X87MODEF:mode>_<SWI24:mode>_cc_i387): Ditto.
    * config/i386/i386.c (ix86_expand_fp_compare): Remove
    "scratch" argument.
    <case IX86_FPCMP_SAHF>: Do not generate pattern with HImode clobber.
    Emit x86_sahf_1 pattern.
    (ix86_expand_compare): Update call to ix86_expand_fp_compare.
    (ix86_expand_carry_flag_compare): Ditto.

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

Committed to mainline SVN.

Uros.

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