On 12/04/12 16:48, Richard Earnshaw wrote:
If negation in Neon needs a scratch register, it seems to me to be
somewhat odd that we're disparaging the ARM version.
Also, wouldn't it be sensible to support a variant that was
early-clobber on operand 0, but loaded immediate zero into that value first:
vmov Dd, #0
vsub Dd, Dd, Dm
That way you'll never need more than two registers, whereas today you
want three.
This patch implements the changes you suggested.
I've done a full bootstrap and test and found no regressions.
OK?
Andrew
P.S. This patch can't actually be committed until my "NEON DImode
immediate constants" patch is approved and committed. (Without that the
load #0 needs a constant pool, and loading constants this late has a bug
at -O0.)
