Add a fast path for comparing fields in “transition: all”.#57560
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chromium-wpt-export-bot merged 1 commit intomasterfrom Feb 4, 2026
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Add a fast path for comparing fields in “transition: all”.#57560chromium-wpt-export-bot merged 1 commit intomasterfrom
chromium-wpt-export-bot merged 1 commit intomasterfrom
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If the author writes “transition: all”, we essentially treat that as a shorthand with 100+ longhands. However, most of the time, almost all of those longhands will end up early-aborting due to the old and new properties being the same. Do that comparison up-front instead; this allows us to skip entire groups if they are shared, and also allows straight-line comparison code instead of going through a large switch every time. Speedometer3 (M1 Pinpoint, LTO but no PGO, significant results at 99% CI only): TodoMVC-Preact-Complex-DOM [ -1.3%, -0.0%] TodoMVC-JavaScript-ES6-Webpack-Complex-DOM [ -1.0%, -0.2%] NewsSite-Next [ -1.6%, -1.1%] NewsSite-Nuxt [ -1.6%, -1.3%] Score [ +0.1%, +0.4%] Bug: 475091954 Change-Id: Iea61d1455265443c131729ae63c20bcbc39deaea Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7493822 Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org> Commit-Queue: Steinar H Gunderson <sesse@chromium.org> Cr-Commit-Position: refs/heads/main@{#1579359}
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If the author writes “transition: all”, we essentially treat that
as a shorthand with 100+ longhands. However, most of the time,
almost all of those longhands will end up early-aborting due to
the old and new properties being the same. Do that comparison
up-front instead; this allows us to skip entire groups if they
are shared, and also allows straight-line comparison code
instead of going through a large switch every time.
Speedometer3 (M1 Pinpoint, LTO but no PGO, significant results
at 99% CI only):
TodoMVC-Preact-Complex-DOM [ -1.3%, -0.0%]
TodoMVC-JavaScript-ES6-Webpack-Complex-DOM [ -1.0%, -0.2%]
NewsSite-Next [ -1.6%, -1.1%]
NewsSite-Nuxt [ -1.6%, -1.3%]
Score [ +0.1%, +0.4%]
Bug: 475091954
Change-Id: Iea61d1455265443c131729ae63c20bcbc39deaea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7493822
Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org>
Commit-Queue: Steinar H Gunderson <sesse@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1579359}