Add flag --always-use-string-forwarding-table to always use the
forwarding table (usually only used for shared strings) instead of
ThinString migrations initially (during GC strings will be migrated
to normal ThinStrings). The goal is to get more coverage of this code
that is designed for shared strings.
Bug: v8:12007
Change-Id: I7eb2e5ccf0018c4ac349611aebe337d8288de5c8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3536650
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80206}
This is a reland of commit 8ba60b7a8e
Changes to original:
- Weaken DCHECK in MakeThin to allow direct transitions of shared
strings during deserialization. This is safe as the string to be
transitioned is freshly created and hasn't escaped the thread yet.
- To enable this, add has_active_deserializer() to LocalIsolate
- Shared thin string transitions are subject to the same layout changes
as non-shared thin string transitions, thus treat them equally when
checking if a map transition is safe.
Original change's description:
> [string] Non-transitioning shared strings
>
> Instead of transitioning shared strings to ThinString on
> internalization, use a forwarding table to the internalized string and
> store the index into the forwarding table in the string's hash field.
>
> This way we don't need to handle concurrent string transitions that
> modify the underlying string data.
>
> During stop-the-world GC, live strings in the forwarding table are
> migrated to regular ThinStrings.
>
> Bug: v8:12007
> Change-Id: I6c6f3d41c6f644e0aaeafbf25ecec5ce0aa0d2d8
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3536647
> Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
> Reviewed-by: Jakob Linke <jgruber@chromium.org>
> Reviewed-by: Shu-yu Guo <syg@chromium.org>
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Commit-Queue: Patrick Thier <pthier@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#79801}
Bug: v8:12007
Change-Id: I022e5c4768b763a86bb28c9c82218c3b807371a0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3571817
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Jakob Linke <jgruber@chromium.org>
Commit-Queue: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80183}
This reverts commit 8ba60b7a8e.
Reason for revert: code_serializer failures: https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux%20-%20debug/38940/overview
Original change's description:
> [string] Non-transitioning shared strings
>
> Instead of transitioning shared strings to ThinString on
> internalization, use a forwarding table to the internalized string and
> store the index into the forwarding table in the string's hash field.
>
> This way we don't need to handle concurrent string transitions that
> modify the underlying string data.
>
> During stop-the-world GC, live strings in the forwarding table are
> migrated to regular ThinStrings.
>
> Bug: v8:12007
> Change-Id: I6c6f3d41c6f644e0aaeafbf25ecec5ce0aa0d2d8
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3536647
> Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
> Reviewed-by: Jakob Linke <jgruber@chromium.org>
> Reviewed-by: Shu-yu Guo <syg@chromium.org>
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Commit-Queue: Patrick Thier <pthier@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#79801}
Bug: v8:12007
Change-Id: I740904f3edfc395331f06c7218e89476b06b0563
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3574543
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Owners-Override: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#79810}
Instead of transitioning shared strings to ThinString on
internalization, use a forwarding table to the internalized string and
store the index into the forwarding table in the string's hash field.
This way we don't need to handle concurrent string transitions that
modify the underlying string data.
During stop-the-world GC, live strings in the forwarding table are
migrated to regular ThinStrings.
Bug: v8:12007
Change-Id: I6c6f3d41c6f644e0aaeafbf25ecec5ce0aa0d2d8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3536647
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Jakob Linke <jgruber@chromium.org>
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79801}
This CL fixes 2 issues with string internalization when the string table
is shared:
1. In-place migration of a string's map to Internalized was done before
it was sure that the string is going to be internalized (outside the
critical section). To fix this problem StringTableKey::AsHandle() is
now split into StringTableKey::PrepareForInsertion(), which is
invoked outside the critical section and creates a copy if
necessary, and StringTableKey::GetHandleForInsertion(), which is
invoked inside the critical section only for string table misses.
Migration of the map is handled by this method.
2. TryStringToIndexOrLookupExisting() didn't handle already internalized
strings. So far this was impossible, as this method was only invoked
for strings that were checked not to be internalized. However with
a shared string table, the string could be internalized after the
checks.
Bug: v8:12007
Change-Id: I193d6b54dc41360eee47d21cbcaa36d2652d85dd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3368103
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78600}
This is a temporary solution so prototyping of shared structs and shared
strings can be worked on in parallel.
Bug: v8:12007
Change-Id: Ic849ec66da1d3824d50d695f16e4b77380afa015
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3379222
Reviewed-by: Patrick Thier <pthier@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78570}
For shared strings, String::MakeThin is protected by using the map word
of the string being migrated as a spinlock.
Note that this CL does not make it safe yet to access character data
from multiple threads. The spinlock here only protects write-write races
in String::MakeThin.
For more information, see the following two design docs:
https://docs.google.com/document/d/1c5i8f2EfKIQygGZ23hNiGxouvRISjUMnJjNsOodj6z0/edithttps://docs.google.com/document/d/1Drzigf17t4ofy0evDmaIL5p0MDZuAl95c9fSeX-QjVg/edit
Bug: v8:12007
Change-Id: I9c47412c6ec7360a672b65a8576b4f6156ee5846
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3313429
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Patrick Thier <pthier@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78257}
The is_shared bit bumps the number of reserved bits for Strings'
InstanceType from 6 to 7. This has the side effect of shuffling the
InstanceType enum values.
There are no users of this bit yet. This is steps 1-2 from the following
design doc [1], in preparation for sharing internalized and
in-place-internalizable strings.
[1] https://docs.google.com/document/d/1c5i8f2EfKIQygGZ23hNiGxouvRISjUMnJjNsOodj6z0/edit?usp=sharing
Bug: v8:12007
Change-Id: Idf11a6035305f0375b4f824ffd32a64f6b5b043b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3266017
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77831}
Also skip the test-shared-strings/YoungInternalization cctest, which
doesn't make sense when there is no young generation.
Bug: v8:12007
Change-Id: I3006960181a7da681d7318289a6ade6b0f0bf6da
Cq-Include-Trybots: luci.v8.try:v8_linux64_single_generation_dbg_ng
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3218197
Auto-Submit: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77371}
When --shared-string-table is passed, in-place-internalizable strings
are promoted into the shared old space to maintain the invariant that
in-place internalization can be done without copying.
Also some drive-by comment fixes and removal of unnecessary 'explicit'
on multi-parameter constructors.
Bug: v8:12007
Change-Id: I467d865e41934b1d5cdf85cbecc85c4befbfeb21
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3193591
Auto-Submit: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77326}
To prepare for prototyping shared memory features, all internalized and
in-place internalizable (1- and 2-byte seq strings and external strings)
will always be allocated in the shared old space.
Cons strings, thin strings, and sliced strings remain allocated in the
thread-local space. They are copied over to the shared space when
internalized, as internalization implies flattening, which for these
strings requires a copy already.
To make the in-place internalization threadsafe, updating the map of
such strings is now done with a release store.
This CL does not yet support external strings.
Bug: v8:12007
Change-Id: I982c35c5120bf4c0c70c5294ce011b47430414c8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3140784
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77308}
