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    SubjectRe: [PATCH] add slice by 8 algorithm to crc32.c
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    Joakim Tjernlund/Transmode wrote on 2011/08/08 13:11:14:
    >
    > "George Spelvin" <linux@horizon.com> wrote on 2011/08/08 12:52:01:
    > >
    > > > I prefer to keep the current code which (at the time) generated good code
    > > > for at least ppc:
    > > > /* Align it */
    > > > if (unlikely((long)buf & 3 && len)) {
    > > > do {
    > > > DO_CRC(*buf++);
    > > > } while ((--len) && ((long)buf)&3);
    > > > }
    > >
    > > Ah, I was looking at fzago's initial patch; I hadn't realized you'd
    > > tweaked it. That's pretty much what I was talking about.
    > >
    > > Would
    > > if (unlikely((long)buf & 3) && len) {
    > >
    > > give the compiler better hints? len != 0 is awfully
    > > likely, actually.
    >
    > Doesn't matter on ppc(gcc 4.4.4). The whole while loop is moved out of line
    > in both cases and the generated asm is identical.

    Actually, it does make a difference(must remember to save file before gcc :)
    Hard to tell if its any better though. Strangle this impacted the inner loop as well,
    it gained an extra addi.

    Jocke



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