wasmtime / PR #14798 fix(x64): lower i64x2 narrowing oper... · git-wasmtime

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Topic: wasmtime / PR #14798 fix(x64): lower i64x2 narrowing oper...

Wasmtime GitHub notifications bot (Oct 18 2026 at 08:44):

shrayjaiswal050-design opened PR #14798 from shrayjaiswal050-design:fix/x64-i64x2-narrow to bytecodealliance:main:

Fixes #4734.

The x64 backend was missing the general snarrow and unarrow lowerings for i64x2 inputs. As a result, valid i64x2 -> i32x4 operations failed during compilation.

This adds SSE2-compatible lowerings that:

Saturate signed values for snarrow.

Treat unarrow inputs as signed i64 values and clamp them to [0, u32::MAX].

Preserve the expected lane order.

Keep the existing optimized conversion-specific lowerings.

Tests cover saturation boundaries, negative values, lane ordering, loaded values, and live inputs.

Checks:

702 x64/runtime/egraph filetests passed.

204 Cranelift codegen unit tests passed.

cargo fmt -p cranelift-codegen -- --check

git diff --check

Wasmtime GitHub notifications bot (Oct 18 2026 at 08:44):

shrayjaiswal050-design requested cfallin for a review on PR #14798.

Wasmtime GitHub notifications bot (Oct 18 2026 at 08:44):

shrayjaiswal050-design requested wasmtime-compiler-reviewers for a review on PR #14798.

Wasmtime GitHub notifications bot (Oct 18 2026 at 10:44):

github-actions[bot] added the label cranelift on PR #14798.

Wasmtime GitHub notifications bot (Oct 18 2026 at 10:44):

github-actions[bot] added the label cranelift:area:x64 on PR #14798.

Wasmtime GitHub notifications bot (Oct 19 2026 at 18:51):

:memo: cfallin submitted PR review:

Thanks! These lowerings look fine to me. Just a nit on the test below.

Wasmtime GitHub notifications bot (Oct 19 2026 at 18:51):

:speech_balloon: cfallin created PR review comment:

Can we add other architectures too if they support this instruction? And at least the Cranelift interpreter, too (and let's add support there if we're missing this case).

Wasmtime GitHub notifications bot (Oct 19 2026 at 19:36):

:memo: shrayjaiswal050-design submitted PR review.

Wasmtime GitHub notifications bot (Oct 19 2026 at 19:36):

:speech_balloon: shrayjaiswal050-design created PR review comment:

Thanks, good point. I’ll extend the test coverage to the other backends that support i64x2 snarrow/unarrow, and make sure the Cranelift interpreter handles and exercises these cases as well. I’ll update the test matrix and rerun the relevant file tests.

Last updated: Oct 31 2026 at 23:03 UTC