565 support for SIMD xfermodes
This uses the most basic approach possible:
- to load an Sk4px from 565, convert to SkPMColors on the stack serially then load those SkPMColors.
- to store an Sk4px to 565, store to SkPMColors on the stack then convert to 565 serially.
Clearly, we can optimize these loads and stores. That's a TODO.
The code using SkPMFloat is the same idea but a little more long-term viable, as we're only operating on one pixel at a time anyway. We could probably write 565 <-> SkPMFloat methods, but I'd rather not until it's really compelling.
The speedups are varied but similar across SSE and NEON: a few uninteresting, many 50% faster, some 2x faster, and SoftLight ~4x faster.
This will cause minor GM diffs, but I don't think any layout test changes.
BUG=skia:
Review URL: https://codereview.chromium.org/1245673002
2 files changed