Wasmtime GitHub notifications bot (Mar 24 2025 at 23:07): Wasmtime GitHub notifications bot (Mar 24 2025 at 23:07):fitzgen requested dicej for a review on PR #10463.
Wasmtime GitHub notifications bot (Mar 24 2025 at 23:07):fitzgen requested wasmtime-core-reviewers for a review on PR #10463.
Wasmtime GitHub notifications bot (Mar 24 2025 at 23:07):fitzgen opened PR #10463 from fitzgen:issue-10459 to bytecodealliance:main:
We were not considering that when a type T is a subtype of type U, that all of
the fields that T and U share must be at the same offsets. Our
reordering/packing algorithm did not consider this. So we stop reordering struct
fields for now.This also means that we cannot guarantee that all GC refs in an object are
contiguously packed anymore. Instead, we maintain a map keyed by
VMSharedTypeIndex, whose value is all the offsets of outgoing GC
references for instances of that type. Tracing looks up the current object's
type in this map, and then extracts each of the GC edges.This new tracing scheme means that we no longer need to store the number of
outgoing edges in the GC object header, and can put the object size in there
again, reducing the DRC header from 24 to 16 bytes.Fixes #10459
Wasmtime GitHub notifications bot (Mar 24 2025 at 23:08):fitzgen edited PR #10463:
Depends on https://github.com/bytecodealliance/wasmtime/pull/10462
We were not considering that when a type T is a subtype of type U, that all of
the fields that T and U share must be at the same offsets. Our
reordering/packing algorithm did not consider this. So we stop reordering struct
fields for now.This also means that we cannot guarantee that all GC refs in an object are
contiguously packed anymore. Instead, we maintain a map keyed by
VMSharedTypeIndex, whose value is all the offsets of outgoing GC
references for instances of that type. Tracing looks up the current object's
type in this map, and then extracts each of the GC edges.This new tracing scheme means that we no longer need to store the number of
outgoing edges in the GC object header, and can put the object size in there
again, reducing the DRC header from 24 to 16 bytes.Fixes #10459
Wasmtime GitHub notifications bot (Mar 24 2025 at 23:29):fitzgen updated PR #10463.
Wasmtime GitHub notifications bot (Mar 25 2025 at 00:48):fitzgen updated PR #10463.
Wasmtime GitHub notifications bot (Mar 25 2025 at 01:03):fitzgen updated PR #10463.
Wasmtime GitHub notifications bot (Mar 25 2025 at 01:04):github-actions[bot] commented on PR #10463:
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Wasmtime GitHub notifications bot (Mar 25 2025 at 10:38):vouillon submitted PR review.
Wasmtime GitHub notifications bot (Mar 25 2025 at 10:38):vouillon created PR review comment:
This assertion fails with the following test module.
(module (type $array (array (mut i64))) (export "_start" (func $f)) (func $f (drop (array.new_fixed $array 0))) )We get this error:
assertion `left == right` failed left: 24 right: 20
Wasmtime GitHub notifications bot (Mar 25 2025 at 14:52):fitzgen submitted PR review.
Wasmtime GitHub notifications bot (Mar 25 2025 at 14:52):fitzgen created PR review comment:
Thanks, this assertion should have been gated on the elements being GC refs
Wasmtime GitHub notifications bot (Mar 25 2025 at 15:28):fitzgen updated PR #10463.
Wasmtime GitHub notifications bot (Mar 25 2025 at 20:55):dicej submitted PR review.
Wasmtime GitHub notifications bot (Mar 25 2025 at 22:08):fitzgen updated PR #10463.
Wasmtime GitHub notifications bot (Mar 25 2025 at 22:08):fitzgen has enabled auto merge for PR #10463.
Wasmtime GitHub notifications bot (Mar 25 2025 at 23:19):fitzgen merged PR #10463.
Last updated: Apr 16 2025 at 19:03 UTC