Stream: git-wasmtime

Topic: wasmtime / PR #14744 cranelift: perf: reduce llvm-lines f...

Wasmtime GitHub notifications bot (Oct 14 2026 at 16:48):

dishmaker opened PR #14744 from dishmaker:dishmaker/cc_display_once to bytecodealliance:main:

This adds .join_display(" ") helper trait that uses core::fmt::Display.
Also, using Display paired with format! is usually faster.

cargo llvm-lines:

• cranelift-codegen: 1720969 -> 1719695 (change: -0.07%)
• cranelift-codegen-meta: 174388 -> 172478 (change -1.1%)

Wasmtime GitHub notifications bot (Oct 14 2026 at 16:50):

dishmaker edited PR #14744:

This adds .join_display(" ") helper trait that uses core::fmt::Display, which cuts few llvm-lines.
Also, using Display paired with format! is usually faster.

cargo llvm-lines:

• cranelift-codegen: 1720969 -> 1719695 (change: -0.07%)
• cranelift-codegen-meta: 174388 -> 172478 (change -1.1%)

Wasmtime GitHub notifications bot (Oct 14 2026 at 16:53):

dishmaker updated PR #14744.

Wasmtime GitHub notifications bot (Oct 14 2026 at 17:17):

dishmaker edited PR #14744:

This adds .join_display(" ") helper trait that uses core::fmt::Display, which cuts few llvm-lines.
Also, using Display paired with format! is usually faster.

cargo llvm-lines:

• cranelift-codegen: 1720969 -> 1719695 (change: -0.07%)
• cranelift-codegen-meta: 174388 -> 172478 (change -1.1%)

Note to reviewers

Similar PR was not accepted in clap, because "it makes the code less idiomatic".

Wasmtime GitHub notifications bot (Oct 14 2026 at 17:17):

dishmaker has marked PR #14744 as ready for review.

Wasmtime GitHub notifications bot (Oct 14 2026 at 17:17):

dishmaker requested wasmtime-compiler-s390x-reviewers for a review on PR #14744.

Wasmtime GitHub notifications bot (Oct 14 2026 at 17:17):

dishmaker requested alexcrichton for a review on PR #14744.

Wasmtime GitHub notifications bot (Oct 14 2026 at 17:17):

dishmaker requested wasmtime-compiler-reviewers for a review on PR #14744.

Wasmtime GitHub notifications bot (Oct 14 2026 at 18:51):

alexcrichton commented on PR #14744:

it makes the code less idiomatic

I'd be inclined to agree with this -- this is a hefty chunk of new code. Can you make a stronger case of why to land this?

Wasmtime GitHub notifications bot (Oct 14 2026 at 19:03):

dishmaker commented on PR #14744:

stronger case

I don't have.

At first, It looked like a simple improvement. I hoped for like 3+% reduction in llvm-lines.

But given it's such a ergonomic change, and not being in a hot-path I leave it to you, if such tricks are worth adding.

Wasmtime GitHub notifications bot (Oct 14 2026 at 19:10):

:cross_mark: alexcrichton closed without merge PR #14744.

Wasmtime GitHub notifications bot (Oct 14 2026 at 19:10):

alexcrichton commented on PR #14744:

Ok, in that case I'm going to close

Last updated: Oct 31 2026 at 23:03 UTC