• Michael Lippautz's avatar
    Reland "cppgc-js,heap: Implement snapshots for embedder fields" · 804aaa5c
    Michael Lippautz authored
    This is a reland of 142dd775
    
    Original change's description:
    > cppgc-js,heap: Implement snapshots for embedder fields
    >
    > https://crrev.com/c/3293410 added concurrent processing of C++ objects
    > found through V8 embedder fields. The CL missed that those embedder
    > fields are not read atomically from JS objects. The problem is that
    > embedder fields are only aligned to kTaggedSize on builds with pointer
    > compression and are as such mis-aligned for atomic ops. This is not a
    > problem for on-heap values as the upper 32bits are anyways computed
    > from the cage. Is is a problem for generic C++ values though, as they
    > are used with Oilpan.
    >
    > This CL adds the standard marker snapshot protocol for embedder fields.
    >
    > Marker:
    > 1. Snapshot embedder fields
    > 2. Try to mark host object
    > 3. On success: process snapshot
    >
    > Main thread:
    > 1. On setting embedder fields mark the object black first
    > 2. Emit a write barrier for the embedder fields
    >
    > This will get simpler with the heap sandbox that uses a separate table
    > for embedder fields. Once the sandbox is the default configuration, we
    > 	can use it as dependency for the concurrent fast path.
    >
    > Bug: chromium:1285706
    > Change-Id: I6b975ea561be08cda840ef0dd27a11627de93900
    > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3380983
    > Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
    > Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
    > Cr-Commit-Position: refs/heads/main@{#78604}
    
    Bug: chromium:1285706
    Change-Id: I024e50fc0757fbcd13cb9ffde027dff55f99d25c
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3386600Reviewed-by: 's avatarDominik Inführ <dinfuehr@chromium.org>
    Reviewed-by: 's avatarOmer Katz <omerkatz@chromium.org>
    Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
    Cr-Commit-Position: refs/heads/main@{#78631}
    804aaa5c
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cpp-heap.h Loading commit data...
cpp-marking-state-inl.h Loading commit data...
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cpp-snapshot.cc Loading commit data...
cpp-snapshot.h Loading commit data...
unified-heap-marking-state.h Loading commit data...
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