Wasmtime GitHub notifications bot (Mar 17 2025 at 23:43): Wasmtime GitHub notifications bot (Mar 17 2025 at 23:43):abrown requested wasmtime-compiler-reviewers for a review on PR #10417.
Wasmtime GitHub notifications bot (Mar 17 2025 at 23:43):abrown requested fitzgen for a review on PR #10417.
Wasmtime GitHub notifications bot (Mar 17 2025 at 23:43):abrown opened PR #10417 from abrown:assembler-fix-10408 to bytecodealliance:main:
In [#10408], the new assembler re-opened an old issue related to unaligned loads with SSE instructions. SSE instructions expect 128-bit aligned loads when using the
m128operand and fault if that is not the case. This had been fixed previously by disallowing load-sinking forXmmMem([#4891]) but more recently we had adopted the use ofXmmMemAlignedincranelift-codegen. Since [#10316] had no knowledge ofXmmMemAligned(onlyXmmMem), it caused the same kind fault--an OOB trap that was in fact an unaligned load.Why didn't CI catch this? Since all the CI machines have AVX and we do not explicitly test the SSE-only case, these unaligned, sunk loads would use the AVX lowering in CI. AVX loads handle unaligned accesses without a fault. This was only discovered during fuzzing when AVX was disabled (i.e.,
--target x86_64-unknown-linux-gnu).To fix this, this change adopts the
XmmMemAlignedtype in the generated assembler code. This is temporary, though: a more lasting fix should pass along an "alignment required" bit from the assembler AST. In the meantime, this closes #10408.[#10408]: https://github.com/bytecodealliance/wasmtime/issues/10408
[#4891]: https://github.com/bytecodealliance/wasmtime/pull/4891
[#10316]: https://github.com/bytecodealliance/wasmtime/pull/10316<!--
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Wasmtime GitHub notifications bot (Mar 17 2025 at 23:44):abrown requested alexcrichton for a review on PR #10417.
Wasmtime GitHub notifications bot (Mar 18 2025 at 00:22):fitzgen submitted PR review.
Wasmtime GitHub notifications bot (Mar 18 2025 at 02:13):github-actions[bot] commented on PR #10417:
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Wasmtime GitHub notifications bot (Mar 18 2025 at 14:44):alexcrichton merged PR #10417.
Last updated: Apr 18 2025 at 09:03 UTC