Wasmtime GitHub notifications bot (Oct 08 2024 at 21:20): Wasmtime GitHub notifications bot (Oct 08 2024 at 21:20):fitzgen requested alexcrichton for a review on PR #9401.
Wasmtime GitHub notifications bot (Oct 08 2024 at 21:20):fitzgen requested wasmtime-core-reviewers for a review on PR #9401.
Wasmtime GitHub notifications bot (Oct 08 2024 at 21:20):fitzgen opened PR #9401 from fitzgen:ref-test to bytecodealliance:main:
This commit implements the
ref.testinstruction, which tests whether a reference is of a given type.We implement inline fast paths for abstract types, but currently rely on an out-of-line libcall for concrete types in the general case. This is known to be suboptimal. (FWIW, we also emit a fast path in front of the libcall where we first check the actual type and expected type for equality and skip the libcall if they are equal.)
This implementation is expected to be improved in the future by exposing a module's types' supertypes arrays to Wasm, so that the Wasm can do the O(1) subtype checks inline. This will make the vast majority of all
ref.tests inlinable. After that, the only remaining case that would require out-of-line libcalls would be when a module is given an instance of a type that it did not itself define (but which could be a subtype of a type it defined, for example, and which itself might not even have been defined until after this module's instance was created!)<!--
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Wasmtime GitHub notifications bot (Oct 08 2024 at 21:31):fitzgen updated PR #9401.
Wasmtime GitHub notifications bot (Oct 08 2024 at 21:39):alexcrichton submitted PR review:
Thanks for all the helpful comments!
Wasmtime GitHub notifications bot (Oct 08 2024 at 21:39):alexcrichton created PR review comment:
Could this be replaced with
.top_type() == Something?
Wasmtime GitHub notifications bot (Oct 08 2024 at 21:42):fitzgen updated PR #9401.
Wasmtime GitHub notifications bot (Oct 08 2024 at 21:42):fitzgen submitted PR review.
Wasmtime GitHub notifications bot (Oct 08 2024 at 21:42):fitzgen created PR review comment:
ah yes, good call
Wasmtime GitHub notifications bot (Oct 08 2024 at 21:45):fitzgen updated PR #9401.
Wasmtime GitHub notifications bot (Oct 08 2024 at 21:45):fitzgen has enabled auto merge for PR #9401.
Wasmtime GitHub notifications bot (Oct 08 2024 at 21:58):fitzgen updated PR #9401.
Wasmtime GitHub notifications bot (Oct 08 2024 at 22:23):fitzgen merged PR #9401.
Last updated: Oct 23 2024 at 20:03 UTC