tree e0160ea752105115ce2d72dc4716384959611fab
parent b2b6a99dcafe7d2f000538af1616e3b49d6c3836
author Mike Klein <mtklein@google.com> 1579020404 -0600
committer Skia Commit-Bot <skia-commit-bot@chromium.org> 1579026296 +0000

improve scalar gather32

This loads 32 bits instead of gathering 256 in the tail part of loops.

To make it work, add a vmovd with SIB addressing.

I also remembered that the mysterious 0b100 is actually a signal that
the instruction uses SIB addressing, and is usually denoted by `rsp`.

(SIB addressing may be something we'd want to generalize over like we
did recently with YmmOrLabel, but I'll leave that for Future Me.)

Slight rewording where "scratch" is mentioned to keep it focused on
scratch GP registers, not "tmp" ymm registers.  Not a hugely important
distinction but helps when I'm grepping through code.

Change-Id: I39a6ab1a76ea0c103ae7d3ebc97a1b7d4b530e73
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/264376
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>