Stream: git-wasmtime

Topic: wasmtime / PR #11035 x64: Migrate `cmpxchg{,16b}` to the ...

Wasmtime GitHub notifications bot (Jun 13 2025 at 16:08):

alexcrichton opened PR #11035 from alexcrichton:x64-cmpxchg to bytecodealliance:main:

A few new operands were needed to define this as well as a number of new instruction "shapes" in a few locations, but nothing too too radical.

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Wasmtime GitHub notifications bot (Jun 13 2025 at 16:08):

alexcrichton requested cfallin for a review on PR #11035.

Wasmtime GitHub notifications bot (Jun 13 2025 at 16:08):

alexcrichton requested wasmtime-compiler-reviewers for a review on PR #11035.

Wasmtime GitHub notifications bot (Jun 13 2025 at 16:30):

alexcrichton updated PR #11035.

Wasmtime GitHub notifications bot (Jun 13 2025 at 16:31):

alexcrichton submitted PR review.

Wasmtime GitHub notifications bot (Jun 13 2025 at 16:31):

alexcrichton created PR review comment:

TIL there's multiple possible encodings for one instruction:

   0:   66 f0 45 0f b1 19       lock cmpxchg %r11w,(%r9)
   6:   f0 66 45 0f b1 19       lock cmpxchg %r11w,(%r9)

Wasmtime GitHub notifications bot (Jun 13 2025 at 16:32):

fitzgen submitted PR review.

Wasmtime GitHub notifications bot (Jun 13 2025 at 16:36):

alexcrichton has enabled auto merge for PR #11035.

Wasmtime GitHub notifications bot (Jun 13 2025 at 17:05):

alexcrichton merged PR #11035.

Wasmtime GitHub notifications bot (Jun 16 2025 at 16:58):

abrown submitted PR review.

Wasmtime GitHub notifications bot (Jun 16 2025 at 16:58):

abrown created PR review comment:

I'm trying to document some of this stuff as I come across it:

https://github.com/bytecodealliance/wasmtime/blob/b4e86667187317d7cd62fe8cfaa2a7479babc3d9/cranelift/assembler-x64/meta/src/dsl/encoding.rs#L477-L485

Last updated: Dec 06 2025 at 06:05 UTC