tree a40efff08f5bfa40b4d01cdc3caf23d30a4c977f
parent 9d23d9bc00efc3f54bb590adeb736193dc19ff6c
author John Stiles <johnstiles@google.com> 1631642843 -0400
committer SkCQ <skcq-be@skia-corp.google.com.iam.gserviceaccount.com> 1631647128 +0000

Optimize zero-splats inside of loops in SkVMCodeGenerator.

Previously, we had various loops which would synthesize a `splat(0)`
instruction on every iteration of the loop. This was harmless and was
already deduplicated by SkVM internally, but in a long loop, this
deduplication process could occur many many times in a row. This hurts
performance needlessly. In particular, for-loops can run for thousands
of iterations in a row, so the savings here can be substantial.

This was inspired by investigation into oss-fuzz:37837.

Change-Id: I247d9ec397418a65219930e2f2b8cf977354bddd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/448837
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>