[skrifa] autohint: use visited set when processing GSUB lookups #1365
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Adds a visited set to GSUB traversal for autohinting to prevent redundant processing of lookups. This can cause a perceived hang on fonts with large complex lookup graphs (like Noto Nastaliq Urdu) even when there are no cycles. Also removes the existing cycle detection code since it is no longer needed. Fixes #1363
cmyr
approved these changes
Feb 21, 2025
| /// Invokes the callback with a memory buffer of the requested size. | ||
| pub(super) fn with_temporary_memory<R>(size: usize, mut f: impl FnMut(&mut [u8]) -> R) -> R { | ||
| // Wrap in a function and prevent inlining to avoid stack allocation | ||
| // and zeroing if we don't take this code path. |
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as in dead code analysis would not prune the branch if it was inlined? Is this a common trick?
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yeah, this just guarantees that we'll never end up with a stack frame that is the sum of all potential buffer sizes. LLVM would probably do a dynamic stack adjustment (alloca style) for each branch but you never know...
drott
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Feb 24, 2025
Release tip of tree with fix for googlefonts#1363 hang in gsub processing during autohinting of Noto Nastaliq. Changes for read-fonts from read-fonts-v0.27.1 to 0.27.1 5657ab8 [chore] Clippy day 53407d0 [read-fonts] CFF charsets (googlefonts#1361) Changes for write-fonts from write-fonts-v0.36.0 to 0.36.0 5657ab8 [chore] Clippy day 029f62f [font_builder] provide more expository comment 7f95b52 [font_builder] test recommended table order a49be74 [font_builder] test checksum_adjustment ffc69ee [font_builder] compute head.checksum_adjustment and sort table in recommended order 53407d0 [read-fonts] CFF charsets (googlefonts#1361) Changes for skrifa from skrifa-v0.28.0 to 0.28.0 e250138 [skrifa] autohint: use visited set when processing GSUB lookups (googlefonts#1365) 441a388 [skrifa] Remove unused write-fonts dev-dep 652b3ca Apply limits to cmap12 iterator (googlefonts#1352) 24fb1c8 [skrifa] tthint: adjust DELTAP/DELTAC limits (googlefonts#1353)
drott
added a commit
that referenced
this pull request
Feb 24, 2025
Release tip of tree with fix for #1363 hang in gsub processing during autohinting of Noto Nastaliq. Changes for read-fonts from read-fonts-v0.27.1 to 0.27.1 5657ab8 [chore] Clippy day 53407d0 [read-fonts] CFF charsets (#1361) Changes for write-fonts from write-fonts-v0.36.0 to 0.36.0 5657ab8 [chore] Clippy day 029f62f [font_builder] provide more expository comment 7f95b52 [font_builder] test recommended table order a49be74 [font_builder] test checksum_adjustment ffc69ee [font_builder] compute head.checksum_adjustment and sort table in recommended order 53407d0 [read-fonts] CFF charsets (#1361) Changes for skrifa from skrifa-v0.28.0 to 0.28.0 e250138 [skrifa] autohint: use visited set when processing GSUB lookups (#1365) 441a388 [skrifa] Remove unused write-fonts dev-dep 652b3ca Apply limits to cmap12 iterator (#1352) 24fb1c8 [skrifa] tthint: adjust DELTAP/DELTAC limits (#1353)
aarongable
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to chromium/chromium
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Mar 7, 2025
This is a cherry-pick to M134, branch 6998, of the fix in https://chromium-review.googlesource.com/c/chromium/src/+/6298807 reduced to only the visited-set fix of GSUB processing in Skrifa from googlefonts/fontations#1365 Updated crates: * skrifa: 0.26.5 => 0.26.6 Skrifa vetted for does-not-implement-crypto, ub-risk-0, safe-to deploy. Bug: chromium:396173460 Change-Id: I38f8be5acb52da1f4fe9312030fecfc56046d946 Disable-Rts: True Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6305501 Reviewed-by: Łukasz Anforowicz <[email protected]> Commit-Queue: Dominik Röttsches <[email protected]> Cr-Commit-Position: refs/branch-heads/6998@{#1867} Cr-Branched-From: de9c6fa-refs/heads/main@{#1415337}
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Adds a visited set to GSUB traversal for autohinting to prevent redundant processing of lookups. This can cause a perceived hang on fonts with large complex lookup graphs (like Noto Nastaliq Urdu) even when there are no cycles.
Also removes the existing cycle detection code since it is no longer needed.
Fixes #1363