Wasmtime GitHub notifications bot (Aug 13 2026 at 19:17): Wasmtime GitHub notifications bot (Aug 13 2026 at 19:17):fitzgen opened PR #14134 from fitzgen:issue-14131 to bytecodealliance:main:
When we eliminate a dead store, we undo the effects that the dead store had on the
LastStorestate. However, querying the last store for a particular region falls back to the last fence, and we were incorrectly restoring that last fence into the region slot, rather than resetting the region slot toNone. While technically incorrect, it was generally benign, but it did lead to "observing" instructions that we didn't mark observed during our initial observation pass, which ultimately led to debug assertion failures.Fixes #14131
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Wasmtime GitHub notifications bot (Aug 13 2026 at 19:17):fitzgen requested alexcrichton for a review on PR #14134.
Wasmtime GitHub notifications bot (Aug 13 2026 at 19:17):fitzgen requested wasmtime-compiler-reviewers for a review on PR #14134.
Wasmtime GitHub notifications bot (Aug 13 2026 at 19:21):alexcrichton unassigned alexcrichton from PR #14134 Alias analysis: do not restore the last-fence into a region slot.
Wasmtime GitHub notifications bot (Aug 13 2026 at 19:21):alexcrichton requested cfallin for a review on PR #14134.
Wasmtime GitHub notifications bot (Aug 13 2026 at 19:46)::thumbs_up: cfallin submitted PR review:
Looks right to me -- very subtle. Thanks for the fix!
Wasmtime GitHub notifications bot (Aug 13 2026 at 19:46):cfallin commented on PR #14134:
(And just to note and make sure it doesn't get missed -- this needs a backport to
release-48.0once merged too. Currently looks like a whitespace issue in a test expectation blocking this merge)
Wasmtime GitHub notifications bot (Aug 13 2026 at 20:58):github-actions[bot] added the label cranelift on PR #14134.
Wasmtime GitHub notifications bot (Aug 13 2026 at 23:00):fitzgen updated PR #14134.
Wasmtime GitHub notifications bot (Aug 13 2026 at 23:01):fitzgen has enabled auto merge for PR #14134.
Wasmtime GitHub notifications bot (Aug 13 2026 at 23:09):fitzgen added PR #14134 Alias analysis: do not restore the last-fence into a region slot to the merge queue.
Wasmtime GitHub notifications bot (Aug 13 2026 at 23:36)::check: fitzgen merged PR #14134.
Wasmtime GitHub notifications bot (Aug 13 2026 at 23:36):fitzgen removed PR #14134 Alias analysis: do not restore the last-fence into a region slot from the merge queue.
Last updated: Aug 30 2026 at 09:07 UTC