For some reason the compiler was optimizing away the reference to the
object in WeakContainerTest.ConservativeGCTracesWeakContainer and thus
not finding it conservatively.
This CL revises the tests such that the compiler is no longer able to
optimize references away.

Bug: v8:12824
Change-Id: Ie598a1cf1124c2983a6c61fd4e990734d36f5832
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3610627Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80257}

Weak containers are retraced if they are found through the stack using
the conservative scanner, possibly resulting in a race with the
concurrent marker.

Bug: v8:12648
Change-Id: I0936a2953e3e2151cea4191f335a091b0e334e6b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3474678
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79184}

Included in this CL:
(*) Introduce CppMarkingState that V8 should use to push references to
    Oilpan. CppMarkingState allocates its own Worklist::Locals to
    support concurrent updates from V8.
(*) Split Oilpan MarkingWorklist object to form a base class used by
    CppMarkingState.
(*) Remove MarkerFactory and split marking initialization. Marking
    worklists should already be initialized when V8 initializes
    visitors. For incremental marking, this requires splitting
    marking initialization and marking start.
(*) Drive-by: Mark JSObject::IsApiWrapper and
    JSObject::IsDroppableApiWrapper as const.

Bug: v8:12407
Change-Id: I35cc816343da86f69a68306204675720e9b3913f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3293410Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78446}

Conceptually, Oilpan uses tri-color marking even though the
implementatin only uses a single mark bit. The difference between gray
and black is represented by the fact that an objet is contained within
a worklist.

Live bytes are accounted on gray->black transition and must only
happen once. This is generally implemented when retrieving an object
from the work list and processing it.

For weak containers this CL fixes the following issues:

1. Weak containers that are strongified during stack scanning were
   double accounted as they were just added to the marking worklist.
   Instead, directly process them during stack scanning.
2. Accounting was missing in case of purely weak collections without
   ephemeron tracing. In such a case, the backing store would not be
   added to a worklist and be considered as black immediately. The fix
   is to directly account the marked bytes in such a scenario.

Bug: chromium:1056170
Change-Id: I350ae1b90ad1753d024a3ce33fc3ec3126a2095d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2900661Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74629}

Exposes an opaque handle for uniformly (cppgc and V8) referring to an
instance of a heap.

Exposes a set of raw write barriers for advances embedders through
subtle::HeapConsistency which is a mirror into write barrier internals.
The following barriers are exposed:
- DijkstraWriteBarrier: Regular Dijkstra-style write barrier (add to
  wavefront);
- DijkstraWriteBarrierRange: Same as DijkstraWriteBarrier but
  operating on a range of slots that are composite (inlined) objects;
- SteeleWriteBarrier: Regular Steele-style write barrier (retreating
  wavefront);

Change-Id: Ib5ac280204686bf887690f72df1cdb506ea6ef70
Bug: chromium:1056170
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2554601Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71381}

This CL adds tracing scopes for the various cppgc classes.
Scopes use TRACE_EVENT_BEGIN and TRACE_EVENT_END macros to report trace
events. To do so they need to include trace-event.h. For unified heap
builds, trace-event.h forwards to v8's src/tracing/trace-event.h. For
other builds, trace-event.h provides a subset of
src/tracing/trace-event.h that covers just the parts used by cppgc.

This CL covers what we need for traces and blink gc metrics (up to
renaming events from BlinkGC.* to CppGC.*). UMA and UKM are not yet
handled.

Bug: chromium:1056170
Change-Id: Id92e84b27259ff0aadae7692f3d79d30896fb8e7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2540548
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71284}

The test was not flaky. Instead it seems compiiler optimizations discarded
of the test-allocated object such that stack scanning could no longer find it.

Bug: v8:11052
Change-Id: Ie8018ccecb03b22e6c4f2dada3e6663b04c551fd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2493160
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Auto-Submit: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70722}

This CL adds TraceWeakContainer and VisitWeakContainer to the Visitor
api. It also introduces the weak_container_worklist_ used to force
re-tracing of weak containers that are reachable from stack.

Bug: chromium:1056170
Change-Id: I4ba75bd64939b8df9ece7422828a5ac647b03fd1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2491022
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70708}