Stream: git-wasmtime

Topic: wasmtime / PR #13031 [Cranelift] resolves #13306, delete ...

Wasmtime GitHub notifications bot (Apr 10 2026 at 02:15):

myunbin opened PR #13031 from myunbin:fix-ext/red to bytecodealliance:main:

Cause

This regression was caused by the ireduce(xext(a) +/- xext(b)) -> a +/- b simplification rules added in cranelift/codegen/src/opts/arithmetic.isle.

These rewrites only check that both operands are extended to the same wide type (cty). They do not verify that the original operand types match the final reduced type (ty), or even match each other.

For example, a pattern such as:

• ireduce.i32 (iadd.i64 (sextend.i64 x:i16) (uextend.i64 y:i32))

can be rewritten into:

• iadd.i32 x, y

which is ill-typed, because x is still i16 while the new instruction expects both operands to be i32.
This matches the verifier failure we observed.

Resolution

We decided to remove these rules for now.

Thanks for reporting this issue.

Wasmtime GitHub notifications bot (Apr 10 2026 at 02:15):

myunbin requested wasmtime-compiler-reviewers for a review on PR #13031.

Wasmtime GitHub notifications bot (Apr 10 2026 at 02:15):

myunbin requested fitzgen for a review on PR #13031.

Wasmtime GitHub notifications bot (Apr 10 2026 at 02:17):

cfallin submitted PR review:

Thanks for the quick response!

Wasmtime GitHub notifications bot (Apr 10 2026 at 02:17):

cfallin has enabled auto merge for PR #13031.

Wasmtime GitHub notifications bot (Apr 10 2026 at 02:38):

cfallin added PR #13031 [Cranelift] resolves #13306, delete extend/reduce rule to the merge queue.

Wasmtime GitHub notifications bot (Apr 10 2026 at 03:03):

cfallin merged PR #13031.

Wasmtime GitHub notifications bot (Apr 10 2026 at 03:03):

cfallin removed PR #13031 [Cranelift] resolves #13306, delete extend/reduce rule from the merge queue.

Last updated: Apr 12 2026 at 23:10 UTC