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    SubjectRe: Big git diff speedup by avoiding x86 "fast string" memcmp
    From: Boaz Harrosh <>
    Date: Wed, 15 Dec 2010 15:15:09 +0200

    > I agree that the byte-compare or long-compare should give you very close
    > results in modern pipeline CPUs. But surly 12 increments-and-test should
    > show up against 3 (or even 2). I would say it must be a better plan.

    For strings of these lengths the setup code necessary to initialize
    the inner loop and the tail code to handle the sub-word ending cases
    eliminate whatever gains there are.

    I know this as I've been hacking on assembler optimized strcmp() and
    memcmp() in my spare time over the past year or so.

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      Last update: 2010-12-15 19:03    [W:0.018 / U:4.372 seconds]
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