This reverts commit 580917d252.
Reason for revert: fix in patchset 2
Original change's description:
> Revert "cppgc: Stack scanning using ObjectStartBitmap"
>
> This reverts commit d3a72e3c2a.
>
> Reason for revert: MSAN failures (https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20arm64%20-%20sim%20-%20MSAN/32360)
>
> Original change's description:
> > cppgc: Stack scanning using ObjectStartBitmap
> >
> > This CL implements stack scanning for cppgc.
> > Given a value on the stack, the MarkingVisitor uses
> > PageBackend::Lookup to checks whether that address is on
> > the heap. If it is, BasePage::TryObjectHeaderFromInnerAddress
> > (introduced in this CL) is used to get the relevant object
> > header. Note that random addresses on the heap might point to
> > free memory, object-start-bitmap, etc.
> >
> > If a valid object header is found:
> > * If the object is not in construction, the GCInfoIndex is used
> > the get the relevant Trace method and the object is traced.
> > * Otherwise, the object is conservatively scanned - i.e. the
> > payload of the object is iterated word by word and each word is
> > treated as a possible pointer.
> >
> > Only addresses pointing to the payload on non-free objects are
> > traced.
> >
> > BasePage::TryObjectHeaderFromInnerAddress assumes on LAB on the
> > relevant space, thus all LABs are reset before scanning the stack.
> >
> > Bug: chromium:1056170
> > Change-Id: I172850f6f1bbb6f0efca8e44ad8fdfe222977b9f
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2190426
> > Commit-Queue: Omer Katz <omerkatz@chromium.org>
> > Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> > Reviewed-by: Anton Bikineev <bikineev@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#67795}
>
> TBR=ulan@chromium.org,mlippautz@chromium.org,bikineev@chromium.org,omerkatz@chromium.org
>
> Change-Id: I3caef6f9f55911fd1a86e895c3495d1b98b1eac2
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: chromium:1056170
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2201136
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#67796}
TBR=ulan@chromium.org,mlippautz@chromium.org,leszeks@chromium.org,bikineev@chromium.org,omerkatz@chromium.org
# Not skipping CQ checks because this is a reland.
Bug: chromium:1056170
Change-Id: If7ea4fe5cb794c07544d5545f5d6548e3375d3ae
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2201137
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67803}
930598427c