Wasmtime GitHub notifications bot (May 27 2026 at 18:53): Wasmtime GitHub notifications bot (May 27 2026 at 18:53):fitzgen opened PR #13498 from fitzgen:wasmtime-issue-13480 to bytecodealliance:main:
In the safepoint spiller, eagerly allocate stack map spill slots when processing a block. This ensures that values that are live-out in the same block can never share a single stack map spill slot, which could otherwise happen with loop-invariant values that need inclusion in stack maps but which "don't" have an overlapping live range with a value defined inside the loop body if you only consider a single iteration (which is effectively what ignoring the live-out set accidentally did).
Supersedes https://github.com/bytecodealliance/wasmtime/pull/13480
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Wasmtime GitHub notifications bot (May 27 2026 at 18:53):fitzgen requested cfallin for a review on PR #13498.
Wasmtime GitHub notifications bot (May 27 2026 at 18:53):fitzgen requested wasmtime-compiler-reviewers for a review on PR #13498.
Wasmtime GitHub notifications bot (May 27 2026 at 18:53):fitzgen requested wasmtime-core-reviewers for a review on PR #13498.
Wasmtime GitHub notifications bot (May 27 2026 at 18:54)::thumbs_up: cfallin submitted PR review:
Thanks!
Wasmtime GitHub notifications bot (May 27 2026 at 18:55):cfallin has enabled auto merge for PR #13498.
Wasmtime GitHub notifications bot (May 27 2026 at 18:58):fitzgen updated PR #13498.
Wasmtime GitHub notifications bot (May 27 2026 at 19:51)::memo: vouillon submitted PR review.
Wasmtime GitHub notifications bot (May 27 2026 at 19:51)::speech_balloon: vouillon created PR review comment:
There are many tests where a value is spilled and never reloaded.
I think stack slots should only be allocated for values inlive_across_any_safepoint.
Wasmtime GitHub notifications bot (May 27 2026 at 20:03):fitzgen updated PR #13498.
Wasmtime GitHub notifications bot (May 27 2026 at 20:03)::memo: fitzgen submitted PR review.
Wasmtime GitHub notifications bot (May 27 2026 at 20:03)::speech_balloon: fitzgen created PR review comment:
Good point!
Wasmtime GitHub notifications bot (May 27 2026 at 20:03):fitzgen has disabled auto merge for PR #13498.
Wasmtime GitHub notifications bot (May 27 2026 at 20:03):fitzgen has enabled auto merge for PR #13498.
Wasmtime GitHub notifications bot (May 27 2026 at 20:04):fitzgen edited PR #13498:
In the safepoint spiller, eagerly allocate stack map spill slots when processing a block. This ensures that values that are live-out in the same block can never share a single stack map spill slot, which could otherwise happen with loop-invariant values that need inclusion in stack maps but which "don't" have an overlapping live range with a value defined inside the loop body if you only consider a single iteration (which is effectively what ignoring the live-out set accidentally did).
Supersedes https://github.com/bytecodealliance/wasmtime/pull/13480
Fixes https://github.com/bytecodealliance/wasmtime/issues/13461
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Wasmtime GitHub notifications bot (May 27 2026 at 20:12):fitzgen added PR #13498 Eagerly allocate stack map spill slots when processing a block to the merge queue.
Wasmtime GitHub notifications bot (May 27 2026 at 20:37)::check: fitzgen merged PR #13498.
Wasmtime GitHub notifications bot (May 27 2026 at 20:37):fitzgen removed PR #13498 Eagerly allocate stack map spill slots when processing a block from the merge queue.
Last updated: Jun 01 2026 at 09:49 UTC