SPARC: unsigned vs. signed int loads
Christian.Thalinger at Sun.COM
Wed Feb 11 09:02:13 PST 2009
On Wed, 2009-02-11 at 11:41 -0500, Paul Hohensee wrote:
> Signed loads require a shifter or mux in the load path, so they can cost
> an extra cycle.
> I think we also use ldub for boolean loads.
Ahh, I see. So it seems that lduw is used to "optimize" the load, but
that's not possible for byte and short loads because they have to be
sign-extended and there is no ldsb-up-to-32-bit. But I doubt that would
be faster than a shift to 64-bit.
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