TypeRef type wraps around another type and it was used to represent
a graph of recursive types. After [0], the only use of TypeRef is
for TypeParameter.bound which may indirectly reference the same
TypeParameter.
This change replaces TypeParameter.bound with TypeParameter.owner and
removes TypeRef entirely. Various parts of the VM no longer need to
handle and support TypeRefs.
TypeParameter.owner can reference a FunctionType, Class,
or, as an optimization, it can be set to null in order to share
class type parameters among different classes.
With the exception of the 'TypeParameter.owner' back pointer,
VM types are now not recursive and can be visited without
additional tracking.
Caveats:
* Generic FunctionType cannot be cloned in a shallow way:
when copying a FunctionType, type parameters should be cloned too
and their owners should be updated. For that reason,
a mapping between 'from' and 'to' function types
(FunctionTypeMapping) is maintained during type transformations
such as InstantiateFrom.
FunctionType::Clone is used instead of Object::Clone where
appropriate.
* When testing types for subtyping and equivalence, mapping
between function types is passed to make sure
type parameters belong to the equivalent function types.
* IL serializer needs to serialize function types as a whole before
serializing any types potentially pointing into the middle of a
function type (such as return type 'List<Y0>' pointing into
the middle of a function type 'List<Y0> Function<Y0>()').
[0] https://dart-review.googlesource.com/c/sdk/+/296300
TEST=ci
Change-Id: I67c2fd0117c6183a45e183919a7847fd1af70b3e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/294165
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
This is a reland of commit c21f7c847c,
BUT the `setExceptionPauseMode` procedure is no longer deleted in this
commit. We are not ready to delete that procedure yet, because deleting
it breaks IDE support: https://github.com/flutter/flutter/issues/117526.
TEST=CI
Original change's description:
> [3.0 alpha][VM/Service] Update VM Service spec to v4.0
>
> This CL updates the VM Service spec to version 4.0 in order to add
> support for records. Some deprecated procedures and properties will also
> be removed in v4.0.
>
> As described in service.md's changelog, this CL:
> Adds `Record` and `RecordType` `InstanceKind`s, adds a deprecation
> notice to the `decl` property of `BoundField`, adds `name` property to
> `BoundField`, adds a deprecation notice to the `parentListIndex`
> property of `InboundReference`, changes the type of the `parentField`
> property of `InboundReference` from `@Field` to `@Field|string|int`,
> adds a deprecation notice to the `parentListIndex` property of
> `RetainingObject`, changes the type of the `parentField` property of
> `RetainingObject` from `string` to `string|int`, removes the deprecated
> `setExceptionPauseMode` procedure, removes the deprecated `timeSpan`
> property from `CpuSamples`, and removes the deprecated `timeSpan`
> property from `CpuSamplesEvent.
>
> TEST=CI
>
> Issue: https://github.com/dart-lang/sdk/issues/49725
> Change-Id: I7bf61c1ba11a0c7fd95a10c9c02c14282062b802
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/268521
> Commit-Queue: Derek Xu <derekx@google.com>
> Reviewed-by: Ben Konyi <bkonyi@google.com>
Change-Id: Ieb96d426b622745e653afd6ca8c9718b1deae0a1
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/278160
Commit-Queue: Derek Xu <derekx@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>
This reverts commit c21f7c847c.
Reason for revert: Appears to cause issues when flutter app is launched with VSCode or Android Studio, please see https://github.com/flutter/flutter/issues/117526
Original change's description:
> [3.0 alpha][VM/Service] Update VM Service spec to v4.0
>
> This CL updates the VM Service spec to version 4.0 in order to add
> support for records. Some deprecated procedures and properties will also
> be removed in v4.0.
>
> As described in service.md's changelog, this CL:
> Adds `Record` and `RecordType` `InstanceKind`s, adds a deprecation
> notice to the `decl` property of `BoundField`, adds `name` property to
> `BoundField`, adds a deprecation notice to the `parentListIndex`
> property of `InboundReference`, changes the type of the `parentField`
> property of `InboundReference` from `@Field` to `@Field|string|int`,
> adds a deprecation notice to the `parentListIndex` property of
> `RetainingObject`, changes the type of the `parentField` property of
> `RetainingObject` from `string` to `string|int`, removes the deprecated
> `setExceptionPauseMode` procedure, removes the deprecated `timeSpan`
> property from `CpuSamples`, and removes the deprecated `timeSpan`
> property from `CpuSamplesEvent.
>
> TEST=CI
>
> Issue: https://github.com/dart-lang/sdk/issues/49725
> Change-Id: I7bf61c1ba11a0c7fd95a10c9c02c14282062b802
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/268521
> Commit-Queue: Derek Xu <derekx@google.com>
> Reviewed-by: Ben Konyi <bkonyi@google.com>
# Not skipping CQ checks because original CL landed > 1 day ago.
Issue: https://github.com/dart-lang/sdk/issues/49725
Change-Id: Ieb2a09653192e165ea8cf68965647e346e3a318b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/277181
Reviewed-by: Derek Xu <derekx@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
Auto-Submit: Siva Annamalai <asiva@google.com>
Commit-Queue: Siva Annamalai <asiva@google.com>
The representation of record shape in record instances and record
types is changed from a pair
int num_fields
Array field_names
to a single integer - packed bitfield
int num_fields(16)
int field_names_index(kSmiBits-16)
where field names index is an index in the array available from
ObjectStore.
With the new representation of record shapes:
1) Size of record instances is reduced.
2) Number of comparisons for a shape test reduced from 2 to 1
(shape test is used during type checks).
3) A few operations removed from Record.hashCode.
4) Type testing stubs (TTS) are now supported for record types with
named fields. Previously it was not possible to check shape of records
with named fields in TTS as TTS cannot access object pool and cannot
load field names array).
TEST=existing
Issue: https://github.com/dart-lang/sdk/issues/49719
Change-Id: I7cdcbb53938aba5d561cd24dc99530395dbbea7e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/276201
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
This CL updates the VM Service spec to version 4.0 in order to add
support for records. Some deprecated procedures and properties will also
be removed in v4.0.
As described in service.md's changelog, this CL:
Adds `Record` and `RecordType` `InstanceKind`s, adds a deprecation
notice to the `decl` property of `BoundField`, adds `name` property to
`BoundField`, adds a deprecation notice to the `parentListIndex`
property of `InboundReference`, changes the type of the `parentField`
property of `InboundReference` from `@Field` to `@Field|string|int`,
adds a deprecation notice to the `parentListIndex` property of
`RetainingObject`, changes the type of the `parentField` property of
`RetainingObject` from `string` to `string|int`, removes the deprecated
`setExceptionPauseMode` procedure, removes the deprecated `timeSpan`
property from `CpuSamples`, and removes the deprecated `timeSpan`
property from `CpuSamplesEvent.
TEST=CI
Issue: https://github.com/dart-lang/sdk/issues/49725
Change-Id: I7bf61c1ba11a0c7fd95a10c9c02c14282062b802
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/268521
Commit-Queue: Derek Xu <derekx@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>
Previously, the VM used a linear array to cache previous instantiations
of a type arguments object. Now once the cache hits a certain number
of occupied entries, the VM changes to using a hash-based approach.
The InstantiateTypeArguments stubs have not yet been updated to
traverse the hash-based cache, so once the cache has grown too large,
all attempts at instantiations, even those that are in the cache, go to
the runtime. Thus, until the stubs are updated, this is only an
improvement if the cost of traversing the linear cache dominates the
cost of making a runtime call. Our benchmarks see a ~40% performance
regression for hash-based caches of size 100 but a ~400% performance
improvement for hash-based caches of size 1000. Thus, we currently
split the difference and set the maximum size of linear caches to 500.
TEST=vm/cc/TypeArguments_Cache_ManyInstantiations
Bug: https://github.com/dart-lang/sdk/issues/48344
Change-Id: I7f1376943523bb5bcd8b175cfb1936779ea73d60
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-linux-product-x64-try,vm-kernel-precomp-linux-release-x64-try,vm-kernel-precomp-nnbd-mac-release-arm64-try,vm-kernel-precomp-nnbd-linux-release-simarm_x64-try,vm-kernel-precomp-linux-release-simarm-try,vm-kernel-precomp-nnbd-linux-release-x64-try,vm-kernel-precomp-nnbd-linux-release-simarm64-try,vm-kernel-precomp-nnbd-linux-debug-simriscv64-try,vm-kernel-precomp-tsan-linux-release-x64-try,vm-kernel-tsan-linux-release-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/265325
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
_InternalLinkedHashMap => _Map
_InternalImmutableLinkedHashMap => _ConstMap
_InternalLinkedHashSet => _Set
_InternalImmutableLinkedHashSet => _ConstSet
This makes things nicer to read in places that display implementation names, such as stack traces, debuggers, profilers and inspectors.
TEST=ci
Change-Id: Iec851c80ea2086cbe79934565dbf35f04809a836
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/266303
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>
This CL adds the parameter `bool include_id` to
`PrintSharedInstanceJSON()` and makes it default to true. This CL also
removes `AddServiceId()` calls that are now unnecessary due to this
change.
TEST=CI
Change-Id: Ica53757a7fc23c70946be71f88408963e5aeae04
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/265041
Reviewed-by: Ben Konyi <bkonyi@google.com>
The new implementation moves away from desugaring of async
functions on kernel AST, state machine generated in the flow graph and
capturing all local variables in the context.
Instead, async/await is implemented using a few stubs
(InitSuspendableFunction, Suspend, Resume, Return and
AsyncExceptionHandler). The stubs are implemented in a
platform-independent way using (macro-)assembler helpers.
When suspending a function, its frame is copied into a SuspendState
object, and when resuming a function it is copied back onto the stack.
No extra code is generated for accessing local variables.
Callback closures are created lazily on the first await.
Design doc: go/compact-async-await.
Part 1 (kernel): https://dart-review.googlesource.com/c/sdk/+/241842
TEST=ci
Issue: https://github.com/dart-lang/sdk/issues/48378
Change-Id: Ibad757035b7cc438ebdff80b460728b1d3eff1f5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/242000
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
This CL implements `NativeFinalizer` in the GC.
`FinalizerEntry`s are extended to track `external_size` and in which
`Heap::Space` the finalizable value is.
On attaching a native finalizer, the external size is added to the
relevant heap. When the finalizable value is promoted from new to old
space, the external size is promoted as well. And when a native
finalizer is run or is detached, the external size is removed from the
relevant heap again.
In contrast to Dart `Finalizer`s, `NativeFinalizer`s are run on isolate
shutdown.
When the `NativeFinalizer`s themselves are collected, the finalizers are
not run. Users should stick the native finalizer in a global variable to
ensure finalization. We will revisit this design when we add send and
exit support, because there is a design space to explore what to do in
that case. This current solution promises the least to users.
In this implementation native finalizers have a Dart entry to clean up
the entries from the `all_entries` field of the finalizer. We should
consider using another data structure that avoids the need for this Dart
entry. See the TODO left in the code.
Bug: https://github.com/dart-lang/sdk/issues/47777
TEST=runtime/tests/vm/dart(_2)/isolates/fast_object_copy_test.dart
TEST=runtime/vm/object_test.cc
TEST=tests/ffi(_2)/vmspecific_native_finalizer_*
Change-Id: I8f594c80c3c344ad83e1f2de10de028eb8456121
Cq-Include-Trybots: luci.dart.try:vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-reload-linux-debug-x64-try,vm-ffi-android-debug-arm64c-try,dart-sdk-mac-arm64-try,vm-kernel-mac-release-arm64-try,pkg-mac-release-arm64-try,vm-kernel-precomp-nnbd-mac-release-arm64-try,vm-kernel-win-debug-x64c-try,vm-kernel-win-debug-x64-try,vm-kernel-precomp-win-debug-x64c-try,vm-kernel-nnbd-win-release-ia32-try,vm-ffi-android-debug-arm-try,vm-precomp-ffi-qemu-linux-release-arm-try,vm-kernel-mac-debug-x64-try,vm-kernel-nnbd-mac-debug-x64-try,vm-kernel-nnbd-linux-debug-ia32-try,benchmark-linux-try,flutter-frontend-try,pkg-linux-debug-try,vm-kernel-asan-linux-release-x64-try,vm-kernel-gcc-linux-try,vm-kernel-optcounter-threshold-linux-release-x64-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-obfuscate-linux-release-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/236320
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Daco Harkes <dacoharkes@google.com>
Original CL in patchset 1.
Split-off https://dart-review.googlesource.com/c/sdk/+/238341
And pulled in fix https://dart-review.googlesource.com/c/sdk/+/238582
(Should merge cleanly when this lands later.)
This CL implements the `Finalizer` in the GC.
The GC is specially aware of two types of objects for the purposes of
running finalizers.
1) `FinalizerEntry`
2) `Finalizer` (`FinalizerBase`, `_FinalizerImpl`)
A `FinalizerEntry` contains the `value`, the optional `detach` key, and
the `token`, and a reference to the `finalizer`.
An entry only holds on weakly to the value, detach key, and finalizer.
(Similar to how `WeakReference` only holds on weakly to target).
A `Finalizer` contains all entries, a list of entries of which the value
is collected, and a reference to the isolate.
When a the value of an entry is GCed, the enry is added over to the
collected list.
If any entry is moved to the collected list, a message is sent that
invokes the finalizer to call the callback on all entries in that list.
When a finalizer is detached by the user, the entry token is set to the
entry itself and is removed from the all entries set.
This ensures that if the entry was already moved to the collected list,
the finalizer is not executed.
To speed up detaching, we use a weak map from detach keys to list of
entries. This ensures entries can be GCed.
Both the scavenger and marker tasks process finalizer entries in
parallel.
Parallel tasks use an atomic exchange on the head of the collected
entries list, ensuring no entries get lost.
The mutator thread is guaranteed to be stopped when processing entries.
This ensures that we do not need barriers for moving entries into the
finalizers collected list.
Dart reads and replaces the collected entries list also with an atomic
exchange, ensuring the GC doesn't run in between a load/store.
When a finalizer gets posted a message to process finalized objects, it
is being kept alive by the message.
An alternative design would be to pre-allocate a `WeakReference` in the
finalizer pointing to the finalizer, and send that itself.
This would be at the cost of an extra object.
Send and exit is not supported in this CL, support will be added in a
follow up CL. Trying to send will throw.
Bug: https://github.com/dart-lang/sdk/issues/47777
TEST=runtime/tests/vm/dart/finalizer/*
TEST=runtime/tests/vm/dart_2/isolates/fast_object_copy_test.dart
TEST=runtime/vm/object_test.cc
Change-Id: Ibdfeadc16d5d69ade50aae5b9f794284c4c4dbab
Cq-Include-Trybots: luci.dart.try:vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-reload-linux-debug-x64-try,vm-ffi-android-debug-arm64c-try,dart-sdk-mac-arm64-try,vm-kernel-mac-release-arm64-try,pkg-mac-release-arm64-try,vm-kernel-precomp-nnbd-mac-release-arm64-try,vm-kernel-win-debug-x64c-try,vm-kernel-win-debug-x64-try,vm-kernel-precomp-win-debug-x64c-try,vm-kernel-nnbd-win-release-ia32-try,vm-ffi-android-debug-arm-try,vm-precomp-ffi-qemu-linux-release-arm-try,vm-kernel-mac-debug-x64-try,vm-kernel-nnbd-mac-debug-x64-try,vm-kernel-nnbd-linux-debug-ia32-try,benchmark-linux-try,flutter-analyze-try,flutter-frontend-try,pkg-linux-debug-try,vm-kernel-asan-linux-release-x64-try,vm-kernel-gcc-linux-try,vm-kernel-optcounter-threshold-linux-release-x64-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-obfuscate-linux-release-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/238086
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Daco Harkes <dacoharkes@google.com>
This reverts commit 7dca34c235.
Reason for revert: b/226085355 dart_vm_test crashing. Unclear what
the cause is. Reverting so we can triage the issue.
TEST=This is a revert.
Original change's description:
> [vm] Implement `Finalizer`
>
> This CL implements the `Finalizer` in the GC.
>
> (This CL does not yet implement `NativeFinalizer`.)
>
> The GC is specially aware of two types of objects for the purposes of
> running finalizers.
>
> 1) `FinalizerEntry`
> 2) `Finalizer` (`FinalizerBase`, `_FinalizerImpl`)
>
> A `FinalizerEntry` contains the `value`, the optional `detach` key, and
> the `token`, and a reference to the `finalizer`.
> An entry only holds on weakly to the value, detach key, and finalizer.
> (Similar to how `WeakReference` only holds on weakly to target).
>
> A `Finalizer` contains all entries, a list of entries of which the value
> is collected, and a reference to the isolate.
>
> When a the value of an entry is GCed, the enry is added over to the
> collected list.
> If any entry is moved to the collected list, a message is sent that
> invokes the finalizer to call the callback on all entries in that list.
>
> When a finalizer is detached by the user, the entry token is set to the
> entry itself and is removed from the all entries set.
> This ensures that if the entry was already moved to the collected list,
> the finalizer is not executed.
>
> To speed up detaching, we use a weak map from detach keys to list of
> entries. This ensures entries can be GCed.
>
> Both the scavenger and marker tasks process finalizer entries in
> parallel.
> Parallel tasks use an atomic exchange on the head of the collected
> entries list, ensuring no entries get lost.
> The mutator thread is guaranteed to be stopped when processing entries.
> This ensures that we do not need barriers for moving entries into the
> finalizers collected list.
> Dart reads and replaces the collected entries list also with an atomic
> exchange, ensuring the GC doesn't run in between a load/store.
>
> When a finalizer gets posted a message to process finalized objects, it
> is being kept alive by the message.
> An alternative design would be to pre-allocate a `WeakReference` in the
> finalizer pointing to the finalizer, and send that itself.
> This would be at the cost of an extra object.
>
> Send and exit is not supported in this CL, support will be added in a
> follow up CL. Trying to send will throw.
>
> Bug: https://github.com/dart-lang/sdk/issues/47777
>
> TEST=runtime/tests/vm/dart/finalizer/*
> TEST=runtime/tests/vm/dart_2/isolates/fast_object_copy_test.dart
> TEST=runtime/vm/object_test.cc
>
> Change-Id: I03e6b4a46212316254bf46ba3f2df333abaa686c
> Cq-Include-Trybots: luci.dart.try:vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-reload-linux-debug-x64-try,vm-ffi-android-debug-arm64c-try,dart-sdk-mac-arm64-try,vm-kernel-mac-release-arm64-try,pkg-mac-release-arm64-try,vm-kernel-precomp-nnbd-mac-release-arm64-try,vm-kernel-win-debug-x64c-try,vm-kernel-win-debug-x64-try,vm-kernel-precomp-win-debug-x64c-try,vm-kernel-nnbd-win-release-ia32-try,vm-ffi-android-debug-arm-try,vm-precomp-ffi-qemu-linux-release-arm-try,vm-kernel-mac-debug-x64-try,vm-kernel-nnbd-mac-debug-x64-try,vm-kernel-nnbd-linux-debug-ia32-try,benchmark-linux-try,flutter-analyze-try,flutter-frontend-try,pkg-linux-debug-try,vm-kernel-asan-linux-release-x64-try,vm-kernel-gcc-linux-try,vm-kernel-optcounter-threshold-linux-release-x64-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-obfuscate-linux-release-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/229544
> Reviewed-by: Lasse Nielsen <lrn@google.com>
> Reviewed-by: Slava Egorov <vegorov@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
> Reviewed-by: Ryan Macnak <rmacnak@google.com>
> Commit-Queue: Daco Harkes <dacoharkes@google.com>
TBR=lrn@google.com,vegorov@google.com,kustermann@google.com,rmacnak@google.com,dacoharkes@google.com
Change-Id: I991f6e49896d18a8d70210cf315d858b462d66c9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: https://github.com/dart-lang/sdk/issues/47777
Cq-Include-Trybots: luci.dart.try:vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-reload-linux-debug-x64-try,vm-ffi-android-debug-arm64c-try,dart-sdk-mac-arm64-try,vm-kernel-mac-release-arm64-try,pkg-mac-release-arm64-try,vm-kernel-precomp-nnbd-mac-release-arm64-try,vm-kernel-win-debug-x64c-try,vm-kernel-win-debug-x64-try,vm-kernel-precomp-win-debug-x64c-try,vm-kernel-nnbd-win-release-ia32-try,vm-ffi-android-debug-arm-try,vm-precomp-ffi-qemu-linux-release-arm-try,vm-kernel-mac-debug-x64-try,vm-kernel-nnbd-mac-debug-x64-try,vm-kernel-nnbd-linux-debug-ia32-try,benchmark-linux-try,flutter-analyze-try,flutter-frontend-try,pkg-linux-debug-try,vm-kernel-asan-linux-release-x64-try,vm-kernel-gcc-linux-try,vm-kernel-optcounter-threshold-linux-release-x64-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-obfuscate-linux-release-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/238080
Reviewed-by: Slava Egorov <vegorov@google.com>
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Commit-Queue: Daco Harkes <dacoharkes@google.com>
This CL implements the `Finalizer` in the GC.
(This CL does not yet implement `NativeFinalizer`.)
The GC is specially aware of two types of objects for the purposes of
running finalizers.
1) `FinalizerEntry`
2) `Finalizer` (`FinalizerBase`, `_FinalizerImpl`)
A `FinalizerEntry` contains the `value`, the optional `detach` key, and
the `token`, and a reference to the `finalizer`.
An entry only holds on weakly to the value, detach key, and finalizer.
(Similar to how `WeakReference` only holds on weakly to target).
A `Finalizer` contains all entries, a list of entries of which the value
is collected, and a reference to the isolate.
When a the value of an entry is GCed, the enry is added over to the
collected list.
If any entry is moved to the collected list, a message is sent that
invokes the finalizer to call the callback on all entries in that list.
When a finalizer is detached by the user, the entry token is set to the
entry itself and is removed from the all entries set.
This ensures that if the entry was already moved to the collected list,
the finalizer is not executed.
To speed up detaching, we use a weak map from detach keys to list of
entries. This ensures entries can be GCed.
Both the scavenger and marker tasks process finalizer entries in
parallel.
Parallel tasks use an atomic exchange on the head of the collected
entries list, ensuring no entries get lost.
The mutator thread is guaranteed to be stopped when processing entries.
This ensures that we do not need barriers for moving entries into the
finalizers collected list.
Dart reads and replaces the collected entries list also with an atomic
exchange, ensuring the GC doesn't run in between a load/store.
When a finalizer gets posted a message to process finalized objects, it
is being kept alive by the message.
An alternative design would be to pre-allocate a `WeakReference` in the
finalizer pointing to the finalizer, and send that itself.
This would be at the cost of an extra object.
Send and exit is not supported in this CL, support will be added in a
follow up CL. Trying to send will throw.
Bug: https://github.com/dart-lang/sdk/issues/47777
TEST=runtime/tests/vm/dart/finalizer/*
TEST=runtime/tests/vm/dart_2/isolates/fast_object_copy_test.dart
TEST=runtime/vm/object_test.cc
Change-Id: I03e6b4a46212316254bf46ba3f2df333abaa686c
Cq-Include-Trybots: luci.dart.try:vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-reload-linux-debug-x64-try,vm-ffi-android-debug-arm64c-try,dart-sdk-mac-arm64-try,vm-kernel-mac-release-arm64-try,pkg-mac-release-arm64-try,vm-kernel-precomp-nnbd-mac-release-arm64-try,vm-kernel-win-debug-x64c-try,vm-kernel-win-debug-x64-try,vm-kernel-precomp-win-debug-x64c-try,vm-kernel-nnbd-win-release-ia32-try,vm-ffi-android-debug-arm-try,vm-precomp-ffi-qemu-linux-release-arm-try,vm-kernel-mac-debug-x64-try,vm-kernel-nnbd-mac-debug-x64-try,vm-kernel-nnbd-linux-debug-ia32-try,benchmark-linux-try,flutter-analyze-try,flutter-frontend-try,pkg-linux-debug-try,vm-kernel-asan-linux-release-x64-try,vm-kernel-gcc-linux-try,vm-kernel-optcounter-threshold-linux-release-x64-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-obfuscate-linux-release-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/229544
Reviewed-by: Lasse Nielsen <lrn@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Daco Harkes <dacoharkes@google.com>
This CL implements `WeakReference` in the VM.
* This reduces the size of weak references from 2 objects using 8 words
to 1 object using 4 words.
* This makes loads of weak reference targets a single load instead of
two.
* This avoids the fix-point in the GC and message object copying for
weak references. (N.b. Weak references need to be processed _after_
the fix-point for weak properties.)
The semantics of weak references in messages is that their target gets
set to `null` if the target is not included in the message by a strong
reference.
The tests take particular care to exercise the case where a weak
reference's target is only kept alive because a weak property key is
alive and it refers to the target in its value. This exercises the fact
that weak references need to be processed last.
Does not add support for weak references in the app snapshot. It would
be dead code until we start using weak references in for example the
CFE.
This CL does not try to unify weak references and weak properties in
the GC or messaging (as proposed in go/dart-vm-weakreference), because
their semantics differ enough.
Closes: https://github.com/dart-lang/sdk/issues/48162
TEST=runtime/tests/vm/dart/finalizer/weak_reference_run_gc_test.dart
TEST=runtime/tests/vm/dart/isolates/fast_object_copy_test.dart
TEST=runtime/vm/object_test.cc
TEST=tests/lib/isolate/weak_reference_message_1_test.dart
TEST=tests/lib/isolate/weak_reference_message_2_test.dart
Change-Id: I3810e919a5866f3ae8a95bd9aa23a880a0b0921c
Cq-Include-Trybots: luci.dart.try:app-kernel-linux-debug-x64-try,dart-sdk-mac-arm64-try,vm-canary-linux-debug-try,vm-fuchsia-release-x64-try,vm-kernel-gcc-linux-try,vm-kernel-asan-linux-release-x64-try,vm-kernel-linux-debug-x64c-try,vm-kernel-linux-debug-x64-try,vm-kernel-linux-debug-simriscv64-try,vm-kernel-mac-debug-x64-try,vm-kernel-nnbd-linux-debug-x64-try,vm-kernel-nnbd-linux-release-ia32-try,vm-kernel-nnbd-linux-release-simarm64-try,vm-kernel-nnbd-linux-release-simarm-try,vm-kernel-nnbd-mac-debug-arm64-try,vm-kernel-nnbd-mac-debug-x64-try,vm-kernel-nnbd-win-release-ia32-try,vm-kernel-nnbd-win-release-x64-try,vm-kernel-optcounter-threshold-linux-release-x64-try,vm-kernel-precomp-android-release-arm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try,vm-kernel-precomp-win-debug-x64c-try,vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-reload-linux-debug-x64-try,vm-kernel-win-debug-ia32-try,vm-kernel-win-debug-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/232087
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Daco Harkes <dacoharkes@google.com>
Every AOT user out there has been using bare instructions mode
and continuing to maintaining non-bare instructions mode simply
adds costs (both in terms of time spent making changes to work
in a mode that is not used and CI resources spent on testing it).
This change removes FLAG_use_bare_instructions and changes the code
to assume that FLAG_precompiled_mode implies bare instructions.
TEST=ci
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try,vm-kernel-precomp-linux-product-x64-try,vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-obfuscate-linux-release-x64-try,app-kernel-linux-release-x64-try,app-kernel-linux-debug-x64-try
Change-Id: I5032b13bfcb613f79865f2cfa139cca8d1b42556
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/220964
Commit-Queue: Slava Egorov <vegorov@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Ryan Macnak