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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/87601] Missed opportunity for flag reuse and macro-op
 fusion on x86
Date: Tue, 21 Dec 2021 11:08:21 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D87601

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
        sub     rsi, 1
        test    esi, esi
        jne     .L3

To
        sub     rsi, 1
        jne     .L3

Is not the same, the first is a 64bit subtract followed by a 32bit compare.=
 in
the 2nd case, you have a 64bit subtract with the 64bit compare happening.=