Wasmtime GitHub notifications bot (May 15 2026 at 05:02): Wasmtime GitHub notifications bot (May 15 2026 at 05:02):HueCodes opened PR #13383 from HueCodes:feat/eh-frame-emission to bytecodealliance:main:
Add
ObjectBuilder::unwind_info(bool). When enabled, the emitted object gains a.eh_framesection with one shared CIE and one FDE per defined function, relocated against the function symbols.The implementation routes cranelift-codegen's existing
UnwindInfo::SystemVthrough gimli'sRelocateWriterinto anobject-crate section. Off by default. Supported on ELF and COFF; Mach-O and Windows unwind formats are deferred and currently no-op or error rather than emit wrong data.Closes #1282.
Wasmtime GitHub notifications bot (May 15 2026 at 05:02):HueCodes requested cfallin for a review on PR #13383.
Wasmtime GitHub notifications bot (May 15 2026 at 05:02):HueCodes requested wasmtime-compiler-reviewers for a review on PR #13383.
Wasmtime GitHub notifications bot (May 15 2026 at 05:02):HueCodes requested fitzgen for a review on PR #13383.
Wasmtime GitHub notifications bot (May 15 2026 at 05:02):HueCodes requested wasmtime-default-reviewers for a review on PR #13383.
Wasmtime GitHub notifications bot (May 15 2026 at 10:09):bjorn3 commented on PR #13383:
Maybe put this behind a feature flag? This wouldn't be usable for rustc_codegen_cranelift as it doesn't allow writing an LSDA.
On arm64 Mach-O it should be possible to emit
__TEXT,__eh_frameby the way: https://github.com/rust-lang/rustc_codegen_cranelift/pull/1634
Wasmtime GitHub notifications bot (May 15 2026 at 13:14):github-actions[bot] added the label cranelift:module on PR #13383.
Wasmtime GitHub notifications bot (May 15 2026 at 13:14):github-actions[bot] added the label cranelift on PR #13383.
Wasmtime GitHub notifications bot (May 15 2026 at 19:40):HueCodes updated PR #13383.
Wasmtime GitHub notifications bot (May 15 2026 at 19:44):HueCodes commented on PR #13383:
@bjorn3 thanks. Done: default-on "unwind" Cargo feature mirroring cranelift-codegen's "unwind", with gimli and ObjectBuilder::unwind_info both gated behind it, so cg_clif drops the dep and API via default-features = false. Kept Mach-O scoped out for now (wrong-reloc risk); TODO left pointing at
cg_clif#1634.
Wasmtime GitHub notifications bot (May 18 2026 at 17:08)::memo: fitzgen submitted PR review:
Thanks! I think we could clean up the boundary between
cfg(feature = "unwind")vscfg(not(feature = "unwind"))a bit.
Wasmtime GitHub notifications bot (May 18 2026 at 17:08)::speech_balloon: fitzgen created PR review comment:
I think this will emit dead code warnings when built without the unwind feature. Will want to
#[cfg(feature = "unwind")]on this.
Wasmtime GitHub notifications bot (May 18 2026 at 17:08)::speech_balloon: fitzgen created PR review comment:
And here
Wasmtime GitHub notifications bot (May 18 2026 at 17:08)::speech_balloon: fitzgen created PR review comment:
And here
Wasmtime GitHub notifications bot (May 18 2026 at 17:08)::speech_balloon: fitzgen created PR review comment:
Yeah better to avoid this by moving the
#[cfg(feature = "unwind")]"up" and avoiding this whole module or any calls into it when the feature is disabled.
Wasmtime GitHub notifications bot (May 18 2026 at 17:08)::speech_balloon: fitzgen created PR review comment:
And here
Wasmtime GitHub notifications bot (May 18 2026 at 17:08)::speech_balloon: fitzgen created PR review comment:
And we also don't want to build any of this module unless
#[cfg(feature = "unwind")].
Wasmtime GitHub notifications bot (May 20 2026 at 03:15):HueCodes updated PR #13383.
Wasmtime GitHub notifications bot (May 20 2026 at 03:17):HueCodes commented on PR #13383:
@fitzgen thanks! Changes made: stub gone, #[cfg(feature = "unwind")] lifted to the field decls, struct init,
and call sites. No cfg(not(feature = "unwind")) branch left.
Wasmtime GitHub notifications bot (May 20 2026 at 16:26)::thumbs_up: fitzgen submitted PR review:
Thanks!
Wasmtime GitHub notifications bot (May 20 2026 at 16:26):fitzgen added PR #13383 cranelift-object: emit .eh_frame for System V unwind info to the merge queue.
Wasmtime GitHub notifications bot (May 20 2026 at 16:53)::check: fitzgen merged PR #13383.
Wasmtime GitHub notifications bot (May 20 2026 at 16:53):fitzgen removed PR #13383 cranelift-object: emit .eh_frame for System V unwind info from the merge queue.
Last updated: Jun 01 2026 at 09:49 UTC