• Clemens Backes's avatar
    Revert "Reland^2 "[serializer] Allocate during deserialization"" · a81da102
    Clemens Backes authored
    This reverts commit c4a062a9.
    
    Reason for revert: TSan issues: https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20TSAN/33504
    
    Original change's description:
    > Reland^2 "[serializer] Allocate during deserialization"
    >
    > This is a reland of 28a30c57
    > which was a reland of 5d7a29c9
    >
    > The crashes were from calling RegisterDeserializerFinished on a null
    > Isolate pointer, for a deserializer that was never initialised
    > (specifically, ReadOnlyDeserializer when ROHeap is shared).
    >
    > Original change's description:
    > > Reland "[serializer] Allocate during deserialization"
    > >
    > > This is a reland of 5d7a29c9
    > >
    > > This reland shuffles around the order of checks in Heap::AllocateRawWith
    > > to not check the new space addresses until it's known that this is a new
    > > space allocation. This fixes an UBSan failure during read-only space
    > > deserialization, which happens before the new space is initialized.
    > >
    > > It also fixes some issues discovered by --stress-snapshot, around
    > > serializing ThinStrings (which are now elided as part of serialization),
    > > handle counts (I bumped the maximum handle count in that check), and
    > > clearing map transitions (the map backpointer field needed a Smi
    > > uninitialized value check).
    > >
    > > Original change's description:
    > > > [serializer] Allocate during deserialization
    > > >
    > > > This patch removes the concept of reservations and a specialized
    > > > deserializer allocator, and instead makes the deserializer allocate
    > > > directly with the Heap's Allocate method.
    > > >
    > > > The major consequence of this is that the GC can now run during
    > > > deserialization, which means that:
    > > >
    > > >   a) Deserialized objects are visible to the GC, and
    > > >   b) Objects that the deserializer/deserialized objects point to can
    > > >      move.
    > > >
    > > > Point a) is mostly not a problem due to previous work in making
    > > > deserialized objects "GC valid", i.e. making sure that they have a valid
    > > > size before any subsequent allocation/safepoint. We now additionally
    > > > have to initialize the allocated space with a valid tagged value -- this
    > > > is a magic Smi value to keep "uninitialized" checks simple.
    > > >
    > > > Point b) is solved by Handlifying the deserializer. This involves
    > > > changing any vectors of objects into vectors of Handles, and any object
    > > > keyed map into an IdentityMap (we can't use Handles as keys because
    > > > the object's address is no longer a stable hash).
    > > >
    > > > Back-references can no longer be direct chunk offsets, so instead the
    > > > deserializer stores a Handle to each deserialized object, and the
    > > > backreference is an index into this handle array. This encoding could
    > > > be optimized in the future with e.g. a second pass over the serialized
    > > > array which emits a different bytecode for objects that are and aren't
    > > > back-referenced.
    > > >
    > > > Additionally, the slot-walk over objects to initialize them can no
    > > > longer use absolute slot offsets, as again an object may move and its
    > > > slot address would become invalid. Now, slots are walked as relative
    > > > offsets to a Handle to the object, or as absolute slots for the case of
    > > > root pointers. A concept of "slot accessor" is introduced to share the
    > > > code between these two modes, and writing the slot (including write
    > > > barriers) is abstracted into this accessor.
    > > >
    > > > Finally, the Code body walk is modified to deserialize all objects
    > > > referred to by RelocInfos before doing the RelocInfo walk itself. This
    > > > is because RelocInfoIterator uses raw pointers, so we cannot allocate
    > > > during a RelocInfo walk.
    > > >
    > > > As a drive-by, the VariableRawData bytecode is tweaked to use tagged
    > > > size rather than byte size -- the size is expected to be tagged-aligned
    > > > anyway, so now we get an extra few bits in the size encoding.
    > > >
    > > > Bug: chromium:1075999
    > > > Change-Id: I672c42f553f2669888cc5e35d692c1b8ece1845e
    > > > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2404451
    > > > Commit-Queue: Leszek Swirski <leszeks@chromium.org>
    > > > Reviewed-by: Jakob Gruber <jgruber@chromium.org>
    > > > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
    > > > Cr-Commit-Position: refs/heads/master@{#70229}
    > >
    > > Bug: chromium:1075999
    > > Change-Id: Ibc77cc48b3440b4a28b09746cfc47e50c340ce54
    > > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2440828
    > > Commit-Queue: Leszek Swirski <leszeks@chromium.org>
    > > Auto-Submit: Leszek Swirski <leszeks@chromium.org>
    > > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
    > > Reviewed-by: Jakob Gruber <jgruber@chromium.org>
    > > Cr-Commit-Position: refs/heads/master@{#70267}
    >
    > Tbr: jgruber@chromium.org,ulan@chromium.org
    > Bug: chromium:1075999
    > Change-Id: Iaa8dc54895866ada0e34a7c9e8fff9ae1cb13f2d
    > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2444991
    > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
    > Commit-Queue: Leszek Swirski <leszeks@chromium.org>
    > Cr-Commit-Position: refs/heads/master@{#70279}
    
    TBR=ulan@chromium.org,jgruber@chromium.org,leszeks@chromium.org
    
    Change-Id: Ib2f01db4cd9b55639d6a4af971bda865edb45e84
    No-Presubmit: true
    No-Tree-Checks: true
    No-Try: true
    Bug: chromium:1075999
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2445250Reviewed-by: 's avatarClemens Backes <clemensb@chromium.org>
    Commit-Queue: Clemens Backes <clemensb@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#70280}
    a81da102
Name
Last commit
Last update
build_overrides Loading commit data...
custom_deps Loading commit data...
docs Loading commit data...
gni Loading commit data...
include Loading commit data...
infra Loading commit data...
samples Loading commit data...
src Loading commit data...
test Loading commit data...
testing Loading commit data...
third_party Loading commit data...
tools Loading commit data...
.clang-format Loading commit data...
.clang-tidy Loading commit data...
.editorconfig Loading commit data...
.flake8 Loading commit data...
.git-blame-ignore-revs Loading commit data...
.gitattributes Loading commit data...
.gitignore Loading commit data...
.gn Loading commit data...
.vpython Loading commit data...
.ycm_extra_conf.py Loading commit data...
AUTHORS Loading commit data...
BUILD.gn Loading commit data...
CODE_OF_CONDUCT.md Loading commit data...
COMMON_OWNERS Loading commit data...
DEPS Loading commit data...
ENG_REVIEW_OWNERS Loading commit data...
INFRA_OWNERS Loading commit data...
INTL_OWNERS Loading commit data...
LICENSE Loading commit data...
LICENSE.fdlibm Loading commit data...
LICENSE.strongtalk Loading commit data...
LICENSE.v8 Loading commit data...
MIPS_OWNERS Loading commit data...
OWNERS Loading commit data...
PPC_OWNERS Loading commit data...
PRESUBMIT.py Loading commit data...
README.md Loading commit data...
S390_OWNERS Loading commit data...
WATCHLISTS Loading commit data...
codereview.settings Loading commit data...