1664735 - Optimize WR sample_gradient

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, enhancement)

Description

[Lee Salzman [:lsalzman]]

There are a few micro-optimizations we can do for WR's sample_gradient that should make it friendlier with SWGL. Integer clamps are much more expensive than FP clamps in SSE2. We can also help the GLSL translator out a bit better with some of the floor/fract common-expressions in case it's not doing a good job.

Comment 1

[Lee Salzman [:lsalzman]]

Attachment: Bug 1664735 - micro-optimizations for WR sample_gradient. r?mattwoodrow

Comment 2

[Lee Salzman [:lsalzman]]

Attachment: Bug 1664735 - support vectorized texelFetchPtr. r?mattwoodrow

Gradient shaders end up calling fetch_from_gpu_cache_2 with a vectorized
address. This currently disables SWGL texelFetchPtr optimization for repeated
uses of texelFetchOffsets. In principle this optimization can still work in
vector mode. We just need to use an I32 instead of a direct pointer into the
buffer in this case. I've added a texelFetchUnchecked wrapper to automagically
disambiguate between scalar and vector cases.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b9ca78d0a835
micro-optimizations for WR sample_gradient. r=mattwoodrow
https://hg.mozilla.org/integration/autoland/rev/5219686dc465
support vectorized texelFetchPtr. r=mattwoodrow

Comment 4

[Noemi Erli[:noemi_erli]]

Backed out 2 changesets (Bug 1664735) for causing failures in repeating-conic-gradient.html CLOSED TREE

Push with failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&group_state=expanded&selectedTaskRun=OjYV4XNHQta64TffRkkvyQ.0&resultStatus=testfailed%2Cbusted%2Cexception&revision=5219686dc46502c8566905a6206c88b245cd69cd

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=315724947&repo=autoland&lineNumber=5283

Backout: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=315724947&repo=autoland&lineNumber=5283

Comment 5

[Pulsebot]

Backout by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/8fa84be67303
Backed out 2 changesets for causing failures in repeating-conic-gradient.html CLOSED TREE

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/acc2af307fe8
micro-optimizations for WR sample_gradient. r=mattwoodrow
https://hg.mozilla.org/integration/autoland/rev/ea8cc0187a75
support vectorized texelFetchPtr. r=mattwoodrow

Comment 7

[Alexandru Michis [:malexandru]]

https://hg.mozilla.org/mozilla-central/rev/acc2af307fe8
https://hg.mozilla.org/mozilla-central/rev/ea8cc0187a75