• Jakob Gruber's avatar
    Reland "[compiler] Consider IsPendingAllocation in Ref construction" · 24ff68e8
    Jakob Gruber authored
    This is the second reland of 4683d6fe
    
    Initial CL:   crrev.com/c/2874663
    First reland: crrev.com/c/2886861
    
    The first reland fixes Ref construction failures in:
    - MapRef::instance_descriptors
    - NativeContext reads (see also crrev.com/c/2891575)
    
    The second reland (this CL):
    - Adds required infrastructure (e.g. kAssumeMemoryFence) but
      without enabling the IsPendingAllocation check. Enabling the check
      will be done separately to avoid further revert chains.
    
    Original change's description:
    > [compiler] Consider IsPendingAllocation in Ref construction
    >
    > The logic in JSHeapBroker::TryGetOrCreateData assumes that parts
    > of the object are safe to read. In particular, the instance type
    > must be readable for the chain of `Is##Name()` type checks.
    >
    > This is guaranteed if
    >
    >  - a global memory fence happened after object initialization and
    >    prior to the read by the compiler; or
    >  - the object was published through a release store and read through
    >    an acquire read.
    >
    > The former is protected by the new call to ObjectMayBeUninitialized
    > (which internally calls IsPendingAllocation) in TryGetOrCreateData.
    >
    > The latter must be marked explicitly by calling the new
    > MakeRefAssumeMemoryFence variant.
    >
    > Note that support in this CL is expected to be incomplete and will
    > have to be extended in the future as more cases show up in which
    > MakeRef calls must be converted to MakeRefAssumeMemoryFence or to
    > TryMakeRef.
    >
    > Bug: v8:7790,v8:11711
    > Change-Id: Ic2f7d9fc46e4bfc3f6bbe42816f73fc5ec174337
    > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2874663
    > Commit-Queue: Jakob Gruber <jgruber@chromium.org>
    > Reviewed-by: Georg Neis <neis@chromium.org>
    > Cr-Commit-Position: refs/heads/master@{#74474}
    
    Bug: v8:7790,v8:11711,chromium:1207680,chromium:1207679
    Change-Id: I123b2962df724a13dd2c7334ae949234bc3bf27a
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2902738Reviewed-by: 's avatarGeorg Neis <neis@chromium.org>
    Commit-Queue: Jakob Gruber <jgruber@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#74638}
    24ff68e8
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