The main contribution of this CL is unification of disparate
handling of various functions like `Future.timeout`,
`Future.wait`, `_SuspendState.createAsyncCallbacks` and
`_SuspendState._createAsyncStarCallback` into a single
`@pragma('vm:awaiter-link')` which allows Dart developers
to specify where awaiter unwinder should look for the next
awaiter.
For example this allows unwinding to succeed for the code like this:
Future<int> outer(Future<int> inner) {
@pragma('vm:awaiter-link')
final completer = Completer<int>();
inner.then((v) => completer.complete(v));
return completer.future;
}
This refactoring also ensures that we preserve information
(including Function & Code objects) required for awaiter
unwinding across all modes (JIT, AOT and AOT with DWARF stack
traces). This guarantees users will get the same information
no matter which mode they are running in. Previously
we have been disabling awaiter_stacks tests in some AOT
modes - which led to regressions in the quality of produced
stacks.
This CL also cleans up relationship between debugger and awaiter
stack returned by StackTrace.current - which makes stack trace
displayed by debugger (used for stepping out and determinining
whether exception is caught or not) and `StackTrace.current`
consistent.
Finally we make one user visible change to the stack trace:
awaiter stack will no always include intermediate listeners
created through `Future.then`. Previously we would sometimes
include these listeners at the tail of the stack trace,
which was inconsistent.
Ultimately this means that code like this:
Future<int> inner() async {
await null; // asynchronous gap
print(StackTrace.current); // (*)
return 0;
}
Future<int> outer() async {
int process(int v) {
return v + 1;
}
return await inner().then(process);
}
void main() async {
await outer();
}
Produces stack trace like this:
inner
<asynchronous suspension>
outer.process
<asynchronous suspension>
outer
<asynchronous suspension>
main
<asynchronous suspension>
And when stepping out of `inner` execution will stop at `outer.process`
first and the next step out will bring execution to `outer` next.
Fixes https://github.com/dart-lang/sdk/issues/52797
Fixes https://github.com/dart-lang/sdk/issues/52203
Issue https://github.com/dart-lang/sdk/issues/47985
TEST=ci
Bug: b/279929839
CoreLibraryReviewExempt: CL just adds @pragma to facilitate unwinding
Cq-Include-Trybots: luci.dart.try:vm-aot-linux-product-x64-try,vm-aot-linux-debug-x64-try,vm-aot-linux-release-x64-try,vm-aot-obfuscate-linux-release-x64-try,vm-aot-dwarf-linux-product-x64-try
Change-Id: If377d5329d6a11c86effb9369dc603a7ae616fe7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/311680
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>
The flag isn't used anywhere in our tests or in embedder code. Turning
it on will result in a VM startup error.
We should therefore remove all uses of the flag and the flag itself.
This is a unmodified reland of
https://dart-review.googlesource.com/c/sdk/+/204500
after some remaining g3 usages have been fixed (the flutter
roll didn't port the GN changes to BUILD changes in g3)
TEST=Existing test suite.
Change-Id: Ic28c9b334a0b04524ee57e2554cc8d713a83fbfb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/204785
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
This reverts commit b1f1aee94d.
Reason for revert: Some left-over uses in g3 need to removed first
(some were removed in b/380758599 but apparently there's some
usages left).
Original change's description:
> [vm] Remove --causal-async-stacks flag
>
> The flag isn't used anywhere in our tests or in embedder code. Turning
> it on will result in a VM startup error.
>
> We should therefore remove all uses of the flag and the flag itself.
>
> TEST=Existing test suite.
>
> Change-Id: I19dfba052df7948dfdb379c0610dab67ebbcd12d
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/204500
> Reviewed-by: Clement Skau <cskau@google.com>
> Commit-Queue: Martin Kustermann <kustermann@google.com>
TBR=kustermann@google.com,cskau@google.com
Change-Id: I03aad46f46153d5ea4ac2fcdd5685d0ef2a0d9af
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/204723
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
The flag isn't used anywhere in our tests or in embedder code. Turning
it on will result in a VM startup error.
We should therefore remove all uses of the flag and the flag itself.
TEST=Existing test suite.
Change-Id: I19dfba052df7948dfdb379c0610dab67ebbcd12d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/204500
Reviewed-by: Clement Skau <cskau@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
This is a reland of b6dc4dad4d
TEST=ci
Original change's description:
> [vm/aot] Avoid using most Code objects in stack traces with --dwarf-stack-traces
>
> The following changes are done in preparation for the removal of Code
> objects in AOT with --dwarf-stack-traces:
>
> * Stack trace objects are extended to hold uword PCs (which may not
> fit into Smi range).
>
> * Scanning stack frames in GC (StackFrame::VisitObjectPointers)
> now avoids using Code objects.
> In order to find CompressedStackMaps it now calls
> ReversePc::FindCompressedStackMaps.
>
> * Singleton Code object (StubCode::UnknownDartCode()) is prepared as
> a replacement for Code objects in stack traces. It has
> PayloadStart() == 0 and Size() == kUwordMax so it includes
> arbitrary PCs.
>
> * In --dwarf-stack-traces mode, most Code objects obtained from stack
> frames are replaced with StubCode::UnknownDartCode().
> This simulates future behavior of ReversePc::Lookup when Code objects
> will be removed.
>
> Issue: https://github.com/dart-lang/sdk/issues/44852
> Change-Id: I7cec7b8b9396c9cfeca3c256a412ba4e82a7e0c4
> TEST=ci
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/182720
> Commit-Queue: Alexander Markov <alexmarkov@google.com>
> Reviewed-by: Tess Strickland <sstrickl@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
Change-Id: Ia2fc4672a085cd963b7fc103369851df3603590c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/186202
Commit-Queue: Vyacheslav Egorov <vegorov@google.com>
Reviewed-by: Tess Strickland <sstrickl@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
This reverts commit b6dc4dad4d.
Reason for revert: broke package:vm_snapshot_analysis in Flutter
(https://github.com/flutter/flutter/issues/76313).
Original change's description:
> [vm/aot] Avoid using most Code objects in stack traces with --dwarf-stack-traces
>
> The following changes are done in preparation for the removal of Code
> objects in AOT with --dwarf-stack-traces:
>
> * Stack trace objects are extended to hold uword PCs (which may not
> fit into Smi range).
>
> * Scanning stack frames in GC (StackFrame::VisitObjectPointers)
> now avoids using Code objects.
> In order to find CompressedStackMaps it now calls
> ReversePc::FindCompressedStackMaps.
>
> * Singleton Code object (StubCode::UnknownDartCode()) is prepared as
> a replacement for Code objects in stack traces. It has
> PayloadStart() == 0 and Size() == kUwordMax so it includes
> arbitrary PCs.
>
> * In --dwarf-stack-traces mode, most Code objects obtained from stack
> frames are replaced with StubCode::UnknownDartCode().
> This simulates future behavior of ReversePc::Lookup when Code objects
> will be removed.
>
> Issue: https://github.com/dart-lang/sdk/issues/44852
> Change-Id: I7cec7b8b9396c9cfeca3c256a412ba4e82a7e0c4
> TEST=ci
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/182720
> Commit-Queue: Alexander Markov <alexmarkov@google.com>
> Reviewed-by: Tess Strickland <sstrickl@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
Issue: https://github.com/dart-lang/sdk/issues/44852
Change-Id: I6f66171eecf1133363a7ce56193e782e43a20baf
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/185488
Reviewed-by: Zach Anderson <zra@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
The following changes are done in preparation for the removal of Code
objects in AOT with --dwarf-stack-traces:
* Stack trace objects are extended to hold uword PCs (which may not
fit into Smi range).
* Scanning stack frames in GC (StackFrame::VisitObjectPointers)
now avoids using Code objects.
In order to find CompressedStackMaps it now calls
ReversePc::FindCompressedStackMaps.
* Singleton Code object (StubCode::UnknownDartCode()) is prepared as
a replacement for Code objects in stack traces. It has
PayloadStart() == 0 and Size() == kUwordMax so it includes
arbitrary PCs.
* In --dwarf-stack-traces mode, most Code objects obtained from stack
frames are replaced with StubCode::UnknownDartCode().
This simulates future behavior of ReversePc::Lookup when Code objects
will be removed.
Issue: https://github.com/dart-lang/sdk/issues/44852
Change-Id: I7cec7b8b9396c9cfeca3c256a412ba4e82a7e0c4
TEST=ci
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/182720
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Tess Strickland <sstrickl@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
All existing embedders have been opted into --lazy-async-stacks, the
VM also uses it as it's default in all configurations.
After this CL, any user of --causal-async-stacks will get an error
message when trying to use it.
=> In any such case, please simply remove the flag.
TEST=Exhaustive CQ.
Bug: https://github.com/dart-lang/sdk/issues/37668
Change-Id: Ia440afcf2dba464aa8b8cf381b93bbac8eb9f8dc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/172564
Commit-Queue: Clement Skau <cskau@google.com>
Reviewed-by: Clement Skau <cskau@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
This reverts commit 5bf9163e1b.
Reason for revert: Tests failing on bots.
Original change's description:
> [ Service / dart:isolate ] Added getPorts RPC and 'debugName' optional
> parameter for ReceivePort and RawReceivePort
>
> This change collects additional information related to ReceivePort
> allocation locations and an optional debug name that will be displayed
> by tooling. ReceivePort is now a special InstanceKind and a ReceivePort
> @Instance will include the port ID, allocation stack trace, and debug
> name.
>
> Change-Id: I003cfff2b7649218e37d9b653c0e953df5d992e7
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/167902
> Reviewed-by: Ryan Macnak <rmacnak@google.com>
TBR=bkonyi@google.com,rmacnak@google.com,asiva@google.com
Change-Id: I39c3abb07c8c40c158eb4549749b076399bccce9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/169160
Reviewed-by: Ben Konyi <bkonyi@google.com>
Commit-Queue: Ben Konyi <bkonyi@google.com>
parameter for ReceivePort and RawReceivePort
This change collects additional information related to ReceivePort
allocation locations and an optional debug name that will be displayed
by tooling. ReceivePort is now a special InstanceKind and a ReceivePort
@Instance will include the port ID, allocation stack trace, and debug
name.
Change-Id: I003cfff2b7649218e37d9b653c0e953df5d992e7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/167902
Reviewed-by: Ryan Macnak <rmacnak@google.com>
This is done by collecting all frames on the current stack until an async/async* frame is hit
which has yielded before (i.e. is not in sync-async case).
From there on it finds the closure of the async/async* frame and starts traversing the listeners:
while (closure != null) {
yield_index = closure.context[Context::kAsyncJumpVarIndex]
pc = closure.function.code.pc_descriptors.LookupPcFromYieldIndex(yield_index);
<emit pc in frame>
closure = closure.context[Context::kAsyncCompleterVarIndex]._future._resultOrListeners.callback;
}
Bug: https://github.com/dart-lang/sdk/issues/37668
Change-Id: I97030d22e529bf8a74ecd30a8a2589cfe57ad330
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/122644
Commit-Queue: Clement Skau <cskau@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Previously there were places in the code where an API accepted a
`bool validate_frames` and call sites passed an enum value (which
implicitly got converted to a bool).
By changing the APIs to require an enum, the compiler will tell us if a
caller doesn't pass one.
Change-Id: I29fcd0b018e6cdd7e00b5bb03e83b9636d1345d4
Reviewed-on: https://dart-review.googlesource.com/57823
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Régis Crelier <regis@google.com>
Proper sequencing of _asyncStackTraceHelper in Kernel
This helper function was being called before its argument was
initialized so it was passing null. Instead, it should be called
after its argument is initialized.
Because the initialization happens in Kernel code, it is simplest to
insert the call explicitly in Kernel code as well as part of the async
transformation. This has the consequence that we now call the helper
function even when the flag causal_async_stacks is false.
Fixes issue #29771.
Fixes issue #30178
Fixes issue #30058
BUG=
R=aam@google.com, asiva@google.com
Review-Url: https://codereview.chromium.org/2936793003 .
Review-Url: https://codereview.chromium.org/2982943002 .
I collected statistics for the sizes and capacities of growable arrays which are promoted to old-space or survive an old-space gc when running dart2js and Fasta. For these applications, the vast majority of arrays stay empty. More than half of the total object size of promoted backing arrays is backing for empty growable arrays.
Furthermore, since the overhead for an array is 3 words (header, type parameters and length), and object sizes are rounded up to an even number of words, we waste one word for all even-sized arrays.
This CL changes the growth strategy so that empty growable arrays are created with a shared, zero-sized array as backing, avoiding the allocation of a backing array if no elements are added. When the array needs to grow, it starts out at 3 and grows to double size plus one each time: 7, 15, 31, ...
A few places in the VM code need to handle these shared, zero-sized arrays specially. In particular, the Array::MakeArray function needs to allocate a new, empty array if its result is to be returned to Dart code.
Benchmarks suggest that the change improves memory usage by a few percent overall and does not significantly affect run time.
BUG=
R=erikcorry@google.com
Review-Url: https://codereview.chromium.org/2949803002 .
This helper function was being called before its argument was
initialized so it was passing null. Instead, it should be called
after its argument is initialized.
Because the initialization happens in Kernel code, it is simplest to
insert the call explicitly in Kernel code as well as part of the async
transformation. This has the consequence that we now call the helper
function even when the flag causal_async_stacks is false.
Fixes#29771.
BUG=
R=aam@google.com, asiva@google.com
Review-Url: https://codereview.chromium.org/2936793003 .
The assertions which tried to assert that we only use
StackFrameIterator to walk frames of the current thread was incorrect.
We already have cases where other threads will walk the stack of the
mutator thread, see below for an example where this can happen.
Thread::VisitObjectPointers was incorrectly passing Thread::Current() to
the StackFrameIterator instead of 'this'. (Code in thread_registry.cc will
loop over a number of threads and calls VisitObjectPointers on them)
Mutator thread:
0 pthread_cond_wait@@GLIBC_2.3.2
1 dart::Monitor::WaitMicros
2 dart::Monitor::Wait
3 dart::MonitorLocker::Wait
4 dart::ThreadBarrier::Sync
5 dart::GCMarker::MarkObjects
6 dart::PageSpace::MarkSweep
7 dart::Heap::CollectOldSpaceGarbage
8 dart::Heap::CollectNewSpaceGarbage
9 dart::Heap::CollectGarbage
10 dart::DN_HelperObject_<native>
11 dart::BootstrapNatives::<native>
<dart frames>
MarkTask thread:
1 dart::EntryFrame::VisitObjectPointers
2 dart::Thread::VisitObjectPointers <---- Walks mutator thread stack
3 dart::ThreadRegistry::VisitObjectPointers <---- Iterates over a number of threads
4 dart::Isolate::VisitStackPointers
5 dart::Isolate::VisitObjectPointers
6 dart::GCMarker::IterateRoots
7 dart::MarkTask::Run
8 dart::ThreadPool::Worker::Loop
9 dart::ThreadPool::Worker::Main
10 dart::ThreadStart
R=rmacnak@google.com
Review-Url: https://codereview.chromium.org/2845053003 .
This CL improves the stack traces that accompany exceptions. Whenever an
async function is entered, we remember how we got there. This is similar
in spirit to package:stack_trace but the implementation is more efficient
and memory usage can be more easily reasoned about.
Tracking causal stack traces:
- [x] Upon entry to an async function, capture the synchronous stack trace prefix and store it into the closure.
- [x] Upon entry to an async* function, capture the synchronous stack trace prefix and store it into the closure.
- [x] Before returning from an async function, clear the Thread's asynchronous stack trace.
- [x] After resuming an async function, load the sychronous stack trace prefix into the Thread.
- [x] Filter stack traces to remove async machinery.
Service protocol changes:
- [x] Send causal async stack trace.
Observatory changes:
- [x] Display causal async stack trace below async functions.
Fixes https://github.com/dart-lang/sdk/issues/27661R=asiva@google.com, rmacnak@google.com
Comparisons: https://docs.google.com/a/google.com/document/d/10r6jEqr8OCiDZ4y9SYU_uOimcHiOGAZMly2ghTErALI/edit?usp=sharing
Review-Url: https://codereview.chromium.org/2646443005 .
The call sequence is very similar to a classic IC call, except the guarded class and the target are loaded indirectly from the constant pool instead of as immediates. In the monomorphic case, we call directly to the expected target with a class check in the callee. In the unlinked, polymorphic and megamorphic cases, we call a stub; these case are now call-through instead of call-and-return.
Every code, except stubs involved in switchable calls, includes the class check sequence at the beginning. So we now distinguish between a checked and an unchecked entry point. Generated code except the switchable call continues to use the unchecked entry point.
PC offsets are calculated relative to the beginning of the instruction stream, rather than either entry point.
BUG=
R=fschneider@google.com
Review URL: https://codereview.chromium.org/2226893002 .
Alexander Markov