Wasmtime GitHub notifications bot (Oct 05 2022 at 19:58): Wasmtime GitHub notifications bot (Oct 05 2022 at 19:58):cfallin opened PR #5023 from fix-struct-ret to main:
The legalization of
StructReturnwas causing issues in the new call-handling code: theStructReturnret was included in theSigDataas if it were an actual CLIF-level return value, but it is not.Prior to using regalloc constraints for return values, we unconditionally included rax (or the architecture's usual return register) as a def, so it would be properly handled as "clobbered" by the regalloc. With the new scheme, we include defs on the call only for CLIF-level outputs. Callees with
StructReturnargs were thus not known to clobber the return-value register, and values might be corrupted.This PR updates the code to include a
StructReturnret as a clobber rather than a returned value in the relevant spots. I observed it causing saves/restores of rax in some CLIF that @bjorn3 provided me, but I was having difficulty minimizing this into a test-case that I would be comfortable including as a precise-output case (including the whole thing verbatim would lock down a bunch of other irrelevant details and cause test-update noise later). If we can find a more minimized example I'm happy to include it as a filetest.Fixes? #5018 (cc @bjorn3 to confirm?).
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Wasmtime GitHub notifications bot (Oct 05 2022 at 19:58):cfallin requested elliottt for a review on PR #5023.
Wasmtime GitHub notifications bot (Oct 05 2022 at 19:58):cfallin requested jameysharp for a review on PR #5023.
Wasmtime GitHub notifications bot (Oct 05 2022 at 20:52):elliottt created PR review comment:
How do you feel about changing the loop bounds to
sigdata.num_rets()-num_rets .. sigdata.num_rets()?
Wasmtime GitHub notifications bot (Oct 05 2022 at 20:52):elliottt submitted PR review.
Wasmtime GitHub notifications bot (Oct 06 2022 at 03:33):cfallin updated PR #5023 from fix-struct-ret to main.
Wasmtime GitHub notifications bot (Oct 06 2022 at 03:43):cfallin updated PR #5023 from fix-struct-ret to main.
Wasmtime GitHub notifications bot (Oct 06 2022 at 03:45):cfallin created PR review comment:
Yup, much better!
Wasmtime GitHub notifications bot (Oct 06 2022 at 03:46):cfallin submitted PR review.
Wasmtime GitHub notifications bot (Oct 06 2022 at 18:35):cfallin has marked PR #5023 as ready for review.
Wasmtime GitHub notifications bot (Oct 06 2022 at 22:13):elliottt submitted PR review.
Wasmtime GitHub notifications bot (Oct 06 2022 at 22:13):elliottt submitted PR review.
Wasmtime GitHub notifications bot (Oct 06 2022 at 22:13):elliottt created PR review comment:
Did this have to be named again to avoid holding a reference to self through the body of the loop?
Wasmtime GitHub notifications bot (Oct 06 2022 at 22:18):cfallin submitted PR review.
Wasmtime GitHub notifications bot (Oct 06 2022 at 22:18):cfallin created PR review comment:
Yep, exactly, this was a borrow-checker appeasement measure. I'll add a comment to that effect.
Wasmtime GitHub notifications bot (Oct 06 2022 at 22:21):cfallin updated PR #5023 from fix-struct-ret to main.
Wasmtime GitHub notifications bot (Oct 06 2022 at 22:22):cfallin has enabled auto merge for PR #5023.
Wasmtime GitHub notifications bot (Oct 07 2022 at 00:14):cfallin merged PR #5023.
Last updated: Dec 23 2024 at 12:05 UTC