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  1. 19 Nov, 2020 1 commit
  3. 17 Nov, 2020 1 commit
  5. 09 Nov, 2020 1 commit
    • Tobias Tebbi's avatar
      Reland "[torque] allow exported classes with custom C++ class" · bd75b0ba
      Tobias Tebbi authored 
      This is a reland of 26f10ecd

Change compared to original CL:
The deserializer changes StrongDescriptorArray to DescriptorArray.
Since this CL uses separate BodyDescriptors for the two kinds of
descriptor arrays, this caused a DCHECK failure when the deserializer
changes the map while the object is visited from the concurrent marking
thread. Fix this by disabling the corresponding checks.


Original change's description:
> [torque] allow exported classes with custom C++ class
>
> Introduce a new annotation @customCppClass that can be used for
> non-extern @export classes, that is, generate everything, remove
> boilerplate from all the internal lists and switches, but allow
> a custom C++ class, which in turn also allows overwriting the generated
> print and verify functions.
>
> Port DescriptorArray and StrongDescriptorArray as an example.
>
> Bug: v8:7793
> Change-Id: I744e52fb4102ac49c0097f1c95bb17d301975bf0
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2489687
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
> Reviewed-by: Seth Brenith <seth.brenith@microsoft.com>
> Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#70989}

Bug: v8:7793
Change-Id: I7505fb111896991d16d7d113704c8c3676669f34
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2526383Reviewed-by: 's avatarNico Hartmann <nicohartmann@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71048}
      bd75b0ba
  7. 05 Nov, 2020 2 commits
  9. 20 Oct, 2020 1 commit
  11. 19 Oct, 2020 1 commit
  13. 07 Oct, 2020 1 commit
    • Leszek Swirski's avatar
      Reland^4 "[serializer] Allocate during deserialization" · 3c508b38
      Leszek Swirski authored 
      This relands commit 3f4e9bbe.
which was a reland of c4a062a9
which was a reland of 28a30c57
which was a reland of 5d7a29c9

The change had an issue that embedders implementing heap tracing (e.g.
Unified Heap with Blink) could be passed an uninitialized pointer if
marking happened during deserialization of an object containing such a
pointer. Because of the 0xdeadbed0 uninitialized filler value, these
embedders would then receive the value 0xdeadbed0deadbed0 as the
'pointer', and crash on dereference.

There is, however, special handling already for null pointers in heap
tracing, also for dealing with not-yet initialized values. So, we can
make the uninitialized Smi filler be 0x00000000, and that will make such
embedded fields have a nullptr representation, making them follow the
normal uninitialized value bailouts.

In addition, it relands the following dependent changes, which are
relanding unchanged and are followup performance improvements.
Relanding them in the same change should allow for cleaner reverts
should they be needed.

This relands commit 76ad3ab5
[identity-map] Change resize heuristic

This relands commit 77cc96aa
[identity-map] Cache the calculated Hash

This relands commit bee5b996
[serializer] Remove Deserializer::Initialize

This relands commit c8f73f22
[serializer] Cache instance type in PostProcessNewObject

This relands commit 4e7c99ab
[identity-map] Remove double-lookups in IdentityMap

Original change's description:
> Reland^3 "[serializer] Allocate during deserialization"
>
> This is a reland of c4a062a9
> which was a reland of 28a30c57
> which was a reland of 5d7a29c9
>
> Fixes TSAN errors from non-atomic writes in the deserializer. Now all
> writes are (relaxed) atomic.
>
> 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: Ib514a4ef16bd02bfb60d046ecbf8fae1ead64a98
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2452689
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Reviewed-by: 's avatarJakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70366}
      3c508b38
  15. 05 Oct, 2020 1 commit
    • Adam Klein's avatar
      Revert "Reland^3 "[serializer] Allocate during deserialization"" · a10ec2be
      Adam Klein authored 
      This reverts commit 3f4e9bbe, along
with the following dependent changes (reverted to make this a clean revert):
76ad3ab5 [identity-map] Change resize heuristic
77cc96aa [identity-map] Cache the calculated Hash
bee5b996 [serializer] Remove Deserializer::Initialize
c8f73f22 [serializer] Cache instance type in PostProcessNewObject
4e7c99ab [identity-map] Remove double-lookups in IdentityMap

Reason for revert: major crash spike on Canary (https://crbug.com/1135027)

Original change's description:
> Reland^3 "[serializer] Allocate during deserialization"
>
> This is a reland of c4a062a9
> which was a reland of 28a30c57
> which was a reland of 5d7a29c9
>
> Fixes TSAN errors from non-atomic writes in the deserializer. Now all
> writes are (relaxed) atomic.
>
> 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: jgruber@chromium.org,ulan@chromium.org
> Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_rel_ng,v8_linux64_tsan_no_cm_rel_ng,v8_linux64_tsan_isolates_rel_ng
> Bug: chromium:1075999
> Change-Id: I0b9b11644aebc4cc8b07c62a0f765b24e4d73d89
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2445872
> Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> Auto-Submit: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#70288}

TBR=ulan@chromium.org,jgruber@chromium.org,leszeks@chromium.org,dinfuehr@chromium.org

Bug: chromium:1075999, chromium:1135027
Change-Id: I5d0d9e49c0302d94ff7291834f5f18e7a0839eb7
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_rel_ng,v8_linux64_tsan_no_cm_rel_ng,v8_linux64_tsan_isolates_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2451030Reviewed-by: 's avatarAdam Klein <adamk@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70328}
      a10ec2be
  17. 02 Oct, 2020 3 commits
    • Leszek Swirski's avatar
      Reland^3 "[serializer] Allocate during deserialization" · 3f4e9bbe
      Leszek Swirski authored 
      This is a reland of c4a062a9
which was a reland of 28a30c57
which was a reland of 5d7a29c9

Fixes TSAN errors from non-atomic writes in the deserializer. Now all
writes are (relaxed) atomic.

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: jgruber@chromium.org,ulan@chromium.org
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_rel_ng,v8_linux64_tsan_no_cm_rel_ng,v8_linux64_tsan_isolates_rel_ng
Bug: chromium:1075999
Change-Id: I0b9b11644aebc4cc8b07c62a0f765b24e4d73d89
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2445872
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: 's avatarDominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70288}
      3f4e9bbe
    • 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
    • Leszek Swirski's avatar
      Reland^2 "[serializer] Allocate during deserialization" · c4a062a9
      Leszek Swirski authored 
      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/+/2444991Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70279}
      c4a062a9
  19. 01 Oct, 2020 2 commits
    • Zhi An Ng's avatar
      Revert "Reland "[serializer] Allocate during deserialization"" · c7c0e790
      Zhi An Ng authored 
      This reverts commit 28a30c57.

Reason for revert: Broke Test262 https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20shared/38638?

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=ulan@chromium.org,jgruber@chromium.org,leszeks@chromium.org

Change-Id: Ieed68332ef6a7ad36db061e3f48be0f28673d7a2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:1075999
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2441608Reviewed-by: 's avatarZhi An Ng <zhin@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70268}
      c7c0e790
    • Leszek Swirski's avatar
      Reland "[serializer] Allocate during deserialization" · 28a30c57
      Leszek Swirski authored 
      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: 's avatarUlan Degenbaev <ulan@chromium.org>
Reviewed-by: 's avatarJakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70267}
      28a30c57
  21. 30 Sep, 2020 2 commits
    • Leszek Swirski's avatar
      Revert "[serializer] Allocate during deserialization" · 74f3665c
      Leszek Swirski authored 
      This reverts commit 5d7a29c9.

Reason for revert: UBSan -- https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20UBSan/13100

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}

TBR=ulan@chromium.org,jgruber@chromium.org,leszeks@chromium.org

Change-Id: I2bd792a24861e8f54897e51522769b50f8f814e2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:1075999
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2440827
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: 's avatarLeszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70231}
      74f3665c
    • Leszek Swirski's avatar
      [serializer] Allocate during deserialization · 5d7a29c9
      Leszek Swirski authored 
      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: 's avatarJakob Gruber <jgruber@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70229}
      5d7a29c9
  23. 14 Aug, 2020 1 commit
    • Leszek Swirski's avatar
      [offthread] Change OffThreadIsolate to LocalIsolate · f1589bbe
      Leszek Swirski authored 
      This patch introduces a new LocalIsolate and LocalFactory, which use
LocalHeap and replace OffThreadIsolate and OffThreadFactory. This allows
us to remove those classes, as well as the related OffThreadSpace,
OffThreadLargeObjectSpace, OffThreadHeap, and OffThreadTransferHandle.
OffThreadLogger becomes LocalLogger.

LocalHeap behaves more like Heap than OffThreadHeap did, so this allows
us to additionally remove the concept of "Finish" and "Publish" that the
OffThreadIsolate had, and allows us to internalize strings directly with
the newly-concurrent string table (where the implementation can now move
to FactoryBase).

This patch also removes the off-thread support from the deserializer
entirely, as well as removing the LocalIsolateWrapper which allowed
run-time distinction between Isolate and OffThreadIsolate. LocalHeap
doesn't support the reservation model used by the deserializer, and we
will likely move the deserializer to use LocalIsolate unconditionally
once we figure out the details of how to do this.

Bug: chromium:1011762

Change-Id: I1a1a0a72952b19a8a4c167c11a863c153a1252fc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2315990
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: 's avatarAndreas Haas <ahaas@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Reviewed-by: 's avatarJakob Gruber <jgruber@chromium.org>
Reviewed-by: 's avatarDominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69397}
      f1589bbe
  25. 06 Aug, 2020 1 commit
    • Leszek Swirski's avatar
      [runtime] Move string table off-heap · 1546be9c
      Leszek Swirski authored 
      Changes the isolate's string table into an off-heap structure. This
allows the string table to be resized without allocating on the V8 heap,
and potentially triggering a GC. This allows existing strings to be
inserted into the string table without requiring allocation.

This has two important benefits:

  1) It allows the deserializer to insert strings directly into the
     string table, rather than having to defer string insertion until
     deserialization completes.

  2) It simplifies the concurrent string table lookup to allow resizing
     the table inside the write lock, therefore eliminating the race
     where two concurrent lookups could both resize the table.

The off-heap string table has the following properties:

  1) The general hashmap behaviour matches the HashTable, i.e. open
     addressing, power-of-two sized, quadratic probing. This could, of
     course, now be changed.

  2) The empty and deleted sentinels are changed to Smi 0 and 1,
     respectively, to make those comparisons a bit cheaper and not
     require roots access.

  3) When the HashTable is resized, the old elements array is kept
     alive in a linked list of previous arrays, so that concurrent
     lookups don't lose the data they're accessing. This linked list
     is cleared by the GC, as then we know that all threads are in
     a safepoint.

  4) The GC treats the hash table entries as weak roots, and only walks
     them for non-live reference clearing and for evacuation.

  5) Since there is no longer a FixedArray to serialize for the startup
     snapshot, there is now a custom serialization of the string table,
     and the string table root is considered unserializable during weak
     root iteration. As a bonus, the custom serialization is more
     efficient, as it skips non-string entries.

As a drive-by, rename LookupStringExists_NoAllocate to
TryStringToIndexOrLookupExisting, to make it clearer that it returns
a non-string for the case when the string is an array index. As another
drive-by, extract StringSet into a separate header.

Bug: v8:10729
Change-Id: I9c990fb2d74d1fe222920408670974a70e969bca
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2339104
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: 's avatarJakob Gruber <jgruber@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69270}
      1546be9c
  27. 31 Jul, 2020 1 commit
    • Dan Elphick's avatar
      [heap] Share RO_SPACE pages with pointer compression · c7d22c49
      Dan Elphick authored 
      This allows the configuration v8_enable_shared_ro_heap and
v8_enable_pointer_compression on Linux and Android, although it still
defaults to off.

When pointer compression and read-only heap sharing are enabled, sharing
is achieved by allocating ReadOnlyPages in shared memory that are
retained in the shared ReadOnlyArtifacts object. These ReadOnlyPages are
then remapped into the address space of the Isolate ultimately using
mremap.

To simplify the creation process the ReadOnlySpace memory for the first
Isolate is created as before without any sharing. It is only when the
ReadOnlySpace memory has been finalized that the shared memory is
allocated and has its contents copied into it. The original memory is
then released (with PC this means it's just released back to the
BoundedPageAllocator) and immediately re-allocated as a shared mapping.

Because we would like to make v8_enable_shared_ro_heap default to true
at some point but can't make this conditional on the value returned by
a method in the code we are yet to compile, the code required for
sharing has been mostly changed to use ifs with
ReadOnlyHeap::IsReadOnlySpaceShared() instead of #ifdefs except where
a compile error would result due to the absence of a class members
without sharing. IsReadOnlySpaceShared() will evaluate
CanAllocateSharedPages in the platform PageAllocator (with pointer
compression and sharing enabled) once and cache that value so sharing
cannot be toggled during the lifetime of the process.

Bug: v8:10454
Change-Id: I0236d752047ecce71bd64c159430517a712bc1e2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2267300
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: 's avatarIgor Sheludko <ishell@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69174}
      c7d22c49
  29. 23 Jul, 2020 1 commit
  31. 22 Jul, 2020 2 commits
  33. 09 Jul, 2020 2 commits
  35. 03 Jul, 2020 1 commit
    • Dan Elphick's avatar
      [ptr-compr] Get Isolate via object address · a3de69da
      Dan Elphick authored 
      To get the Isolate from a HeapObject, rather than masking off the
MemoryChunk and then loading the heap from the MemoryChunk (which won't
work when RO_SPACE is shared between Isolates), get the Isolate by
masking off the bottom 32 bits and apply the Isolate bias.

Also fixes up a stale comment and makes several methods in RootsTable
and Isolate const to support this change.

Bug: v8:10454
Change-Id: I5f8eb873d8486b699460223dbe3454a5dcf1854f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2280088
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: 's avatarIgor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68671}
      a3de69da
  37. 29 Jun, 2020 1 commit
  39. 26 Jun, 2020 2 commits
    • Shu-yu Guo's avatar
      Revert "[wasm-gc] Implement rtt.sub" · 30456566
      Shu-yu Guo authored 
      This reverts commit 04ce88ea.

Reason for revert: TSAN failure: https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20TSAN/32135

Original change's description:
> [wasm-gc] Implement rtt.sub
> 
> RTTs are internally represented as Maps. To store supertype information,
> this patch introduces a WasmTypeInfo object, which is installed on Wasm
> objects' Maps and points at both the off-heap type information and the
> parent RTT.
> In this patch, rtt.sub always creates a fresh RTT. The canonicalization
> that the proposal requires will be implemented later.
> 
> Bug: v8:7748
> Change-Id: I8286dd11f520966155cd95c2bd844ec34fccd131
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2260566
> Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#68564}

TBR=ulan@chromium.org,jkummerow@chromium.org,tebbi@chromium.org

Change-Id: I311732e1ced4de7a58b87d4a9b6056e0d62aa986
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7748
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2270734Reviewed-by: 's avatarShu-yu Guo <syg@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68567}
      30456566
    • Jakob Kummerow's avatar
      [wasm-gc] Implement rtt.sub · 04ce88ea
      Jakob Kummerow authored 
      RTTs are internally represented as Maps. To store supertype information,
this patch introduces a WasmTypeInfo object, which is installed on Wasm
objects' Maps and points at both the off-heap type information and the
parent RTT.
In this patch, rtt.sub always creates a fresh RTT. The canonicalization
that the proposal requires will be implemented later.

Bug: v8:7748
Change-Id: I8286dd11f520966155cd95c2bd844ec34fccd131
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2260566
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: 's avatarTobias Tebbi <tebbi@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68564}
      04ce88ea
  41. 23 Jun, 2020 1 commit
    • Daniel Clifford's avatar
      [torque] generate Cast<> macros from Torque-defined classes · 1052dfb3
      Daniel Clifford authored 
      This change enables automatic generation of Cast<> operators for
classes that are defined in Torque.

* Cast<> macros are generated for all classes that are defined in
  Torque code that are neither shapes nor marked with a new
  @doNotGenerateCast annotation.

* Implicitly generated Cast macros simply call through to an
  internally-defined "DownCastForTorqueClass" macro that implements
  the cast using one of three strategies for efficiency. If the class
  has subclasses (i.e. a range of instance types including subtypes),
  the DownCastForTorqueClass checks for inclusion in the instance type
  range. If the class has a single instance type (i.e. no subclasses),
  then either 1) a map check is used if the class has a globally-
  defined map constant or 2) an equality check for the instance type
  is used.

* Added new intrinsics to introspect class information, e.g. fetching
  instance type ranges for a class, accessing the globally-defined map
  for a class.

* Removed a whole pile of existing explicit Cast<> operators that are
  no longer needed because of the implicitly generated Cast<> macros.

* Added tests for the new Cast<> implementations.

Bug: v8:7793
Change-Id: I3aadb0c62b720e9de4e7978b9ec4f05075771b8b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2250239
Commit-Queue: Daniel Clifford <danno@chromium.org>
Reviewed-by: 's avatarTobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68478}
      1052dfb3
  43. 25 May, 2020 1 commit
  45. 21 May, 2020 1 commit
    • Seth Brenith's avatar
      [diagnostics] Support --turbo-profiling for builtins · 18c73676
      Seth Brenith authored 
      Currently, if d8 is run with the --turbo-profiling flag, it prints info
about every TurboFan-compiled function. This info includes the number of
times that each basic block in the function was run. It also includes
text representations of the function's schedule and code, so that the
person reading the output can associate counters with blocks of code.

The data about each function is currently stored in a
BasicBlockProfiler::Data instance, which is attached to a list owned by
the singleton BasicBlockProfiler. Each Data contains an
std::vector<uint32_t> which represents how many times each block in the
function has executed. The generated code for each block uses a raw
pointer into the storage of that vector to implement incrementing the
counter.

With this change, if you compile with v8_enable_builtins_profiling and
then run with --turbo-profiling, d8 will print that same info about
builtins too.

In order to generate code that can survive being serialized to a
snapshot and reloaded, this change uses counters in the JS heap instead
of a std::vector outside the JS heap. The steps for instrumentation are
as follows:

1. Between scheduling and instruction selection, add code to increment
   the counter for each block. The counters array doesn't yet exist at
   this point, and allocation is disallowed, so at this point the code
   refers to a special marker value.
2. During finalization of the code, allocate a BasicBlockProfilingData
   object on the JS heap containing data equivalent to what is stored in
   BasicBlockProfiler::Data. This includes a ByteArray that is big
   enough to store the counters for each block.
3. Patch the reference in the BuiltinsConstantsTableBuilder so that
   instead of referring to the marker object, it now refers to this
   ByteArray. Also add the BasicBlockProfilingData object to a list that
   is attached to the heap roots so it can be easily accessed for
   printing.

Because these steps include modifying the BuiltinsConstantsTableBuilder,
this procedure is only applicable to builtins. Runtime-generated code
still uses raw pointers into std::vector instances. In order to keep
divergence between these code paths to a minimum, most work is done
referring to instances of BasicBlockProfiler::Data (the C++ class), and
functions are provided to copy back and forth between that type and
BasicBlockProfilingData (the JS heap object).

This change is intended only to make --turbo-profiling work consistently
on more kinds of functions, but with some further work, this data could
form the basis for:
- code coverage info for fuzzers, and/or
- hot-path info for profile-guided optimization.

Bug: v8:10470, v8:9119
Change-Id: Ib556a5bc3abe67cdaa2e3ee62702a2a08b11cb61
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2159738
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Reviewed-by: 's avatarJakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67944}
      18c73676
  47. 14 May, 2020 1 commit
    • Leszek Swirski's avatar
      [offthread] Add off thread deserialization · 595609fb
      Leszek Swirski authored 
      Add a new OffThreadObjectDeserializer, which can deserialize a snapshot
into an OffThreadIsolate.

This involves templating the Deserializer base class on Isolate, and
amending OffThreadHeap to be able to create Reservations same as the
main-thread Heap can. Various off-thread incompatible methods are
stubbed out as UNREACHABLE in OffThreadIsolate overloads.

There is currently no API entry into the off-thread deserialization, but
under --stress-background-compile it now runs the CodeDeserializer (i.e.
code cache deserialization) in a background thread.

Bug: chromium:1075999

Change-Id: I2453f51ae31df4d4b6aa94b0804a9d6d3a03781e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2172741
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: 's avatarJakob Gruber <jgruber@chromium.org>
Reviewed-by: 's avatarIgor Sheludko <ishell@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67799}
      595609fb
  49. 13 May, 2020 1 commit
  51. 12 May, 2020 1 commit
  53. 08 May, 2020 1 commit
  55. 07 May, 2020 1 commit
  57. 06 May, 2020 2 commits
  59. 04 May, 2020 1 commit
  61. 28 Apr, 2020 1 commit