[PATCH, i386]: Generate xlat insn

Uros Bizjak ubizjak@gmail.com
Tue Sep 25 07:48:00 GMT 2007


On 9/25/07, Chris Lattner <clattner@apple.com> wrote:

> > This small patch implements xlat insn. With attached patch,
> > following testcase:

> Out of curiosity, why do this at all?  Your example above doesn't
> make a compelling case for a size win here, and xlat seems like it
> would always be slower than the equivalent load.  Is there a recent
> x86 implementation where your first asm is faster than the second chunk?

Not that I know of. I was just experimenting with xlat, looking for
optimization opportunities (performance or code size) using this insn.
It looks that there is only a marginal 1byte code size reduction
(including push and pop of %ebx) with possible performance
degradation.

Uros.



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