Messages in this thread | | | Date | 24 Sep 2012 09:56:14 -0400 | From | "George Spelvin" <> | Subject | Re: [PATCH 2/4] lib: vsprintf: Optimize division by 10000 |
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Michal Nazarewicz <mpn@google.com> wrote: > Didn't some SPARCs have 32x32->32 multiply? I remember reading some > rant from a GMP developer about how SPARC is broken that way.
SPARCv9 only has 64x64->64; there's no 128-bit result version. That cuts large-integer math speed by a factor of 4 (very crude approximation), to the same speed as 32x32->64.
SPARCv8 UMUL puts the high half of the 64-bit result into the Y register, and SPARCv7 has a multiply-step instruction (MULScc) which does likewise.
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