srcover_SWAR()

Use SIMD-within-a-register to speed up srcover().

Just short of 2x faster, and smaller code size.

Change-Id: I4b8303886bffb389270bf8842bcdfc98a0cb6249
Reviewed-on: https://skia-review.googlesource.com/c/175225
Reviewed-by: Mike Klein <mtklein@google.com>
1 file changed