[Python-Dev] String hash function multiplier (original) (raw)

Andrew MacIntyre andymac at bullseye.apana.org.au
Fri Apr 16 19:36:52 EDT 2004


On Wed, 14 Apr 2004, Jeff Epler wrote:

imul is on all x86 architectures, but whether to use it or not depends on the characteristics of the target CPU. With -mcpu=i386, imul is considered quite slow and a shift sequence is (almost?) always preferred when one operand is constant. With -mcpu=i686 and newer, imul seems to be preferred.

My misunderstanding. I hadn't really comprehended the full extent of "instruction scheduling" in this context.

-- Andrew I MacIntyre "These thoughts are mine alone..." E-mail: andymac at bullseye.apana.org.au (pref) | Snail: PO Box 370 andymac at pcug.org.au (alt) | Belconnen ACT 2616 Web: http://www.andymac.org/ | Australia



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