Commit Graph

40 Commits

Author SHA1 Message Date
Ryan Macnak e3a9d70591 [vm, service] Remove unsafe querying across threads during Isolate::PrintJSON.
Note this would be unsafe even if under a safepoint operation because not all of the queried threads participate in safepoints.

TEST=tsan
Bug: https://github.com/dart-lang/sdk/issues/44304
Bug: https://github.com/dart-lang/sdk/issues/44385
Change-Id: I8156e8c6049165e5c53b66c3391f3e8a496ddaaf
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/175000
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>
2020-12-08 00:36:38 +00:00
Martin Kustermann dae308461c [vm/concurrency] Share [Heap] and [SharedClassTable] between all isolates within one isolate group
This CL:

  * Moves [Heap]/[SharedClassTable] from [Isolate] to [IsolateGroup], which
    will make all isolates in the group use the same heap. The GC will use
    the shared class table for object size information.

  * Adds support for entering/leaving an isolate group as a helper thread
    (e.g. via [Thread::EnterIsolateGroupAsHelper]). The current active
    isolate group can be accessed via TLS `IsolateGroup::Current()` or
    `Thread::isolate_group_`. When entering as a helper thread there will be
    no current isolate.

  * Changes the GC to use the above mechanism and ensures GC works without
    a currently active isolate. The GC will use information purely available via
    [IsolateGroup]. The GC will iterate all isolates within an isolate
    group e.g. for scanning roots.

  * Makes spawning of new isolates start in their own isolate group.
    Once the isolate is fully functional it's heap will be merged into
    the original isolate group

  * Moves ApiState, containing persistent and weak persistent handles,
    from [Isolate] to [IsolateGroup], plus adds appropriate locking.

Issue https://github.com/dart-lang/sdk/issues/36097

Change-Id: Ia8e1d8aa78750e8400864200f4825395a182c004
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/126646
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
2020-02-20 21:08:35 +00:00
Martin Kustermann 0a2993687b [vm/concurrency] Make all isolates within an isolate group coordinate on GCs
This CL moves the thread registry and the safepoint handler to the
[IsolateGroup]. This will cause all threads belonging to the isolate
group to safepoint together.

  => We will therefore start to get an idea of the impact this will have on
  pause times.

So far it was only possible to enter a particular isolate (e.g. as mutator
thread or auxiliary thread). This CL adds support for entering an isolate
group (instead of a particular isolate) as an auxiliarly thread. The
current isolate group is available via `IsolateGroup::Current()`.

  => This is a preparation step to let GC threads enter the isolate
     group as auxiliary threads, not associated with a particular isolate but
     to an isolate group as a whole.

Issue https://github.com/dart-lang/sdk/issues/36097

Change-Id: I7069d07130938d370869f02060570143bfeb1b48
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/108801
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
2019-07-23 10:58:11 +00:00
Martin Kustermann 14ea27e65b [vm/concurrency] Make thread_registry not depend on [Isolate], move mutator thread from thread registry to isolate
The thread registry is creating [Thread] objects when threads enter an
isolate (as mutator or helper). Once threads exit an isolate, the
[Thread] structure is returned and the thread registry will put it
into a cache for later re-use.

The mutator [Thread] object is an exception: Exiting and entering the
isolate as mutator will always use the same cached [Thread] object.

We want to eventually use one thread registry for an entire isolate
group. There will therefore be multiple mutator threads per thread registry.
We therefore move the cached mutator thread from the thread registry to the
[Isolate] object.

Issue https://github.com/dart-lang/sdk/issues/36097

Change-Id: Id27dff886d79ca76f6e05320151aeb72c8ba5140
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/108720
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
2019-07-11 13:36:02 +00:00
Matthew Dempsky 6d5f763952 [vm] Eliminate Mutex/Monitor indirection where possible
In many cases, the Mutexes and Monitors have to be marked "mutable"
because they're used to synchronize const accessor methods.

Small text segment improvement for Product builds:

$ size dart.{arm,x64}.{before,after}
   text	   data	    bss	    dec	    hex	filename
19726069	 409960	 392332	20528361	1393ce9	dart.arm.before
19725525	 409960	 392332	20527817	1393ac9	dart.arm.after
22576021	 600376	1782824	24959221	17cd8f5	dart.x64.before
22574821	 600376	1782824	24958021	17cd445	dart.x64.after

Change-Id: I68f5cd5ad452044df8bfebd160910496036a3e6b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/101745
Commit-Queue: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
2019-05-13 21:17:51 +00:00
Vyacheslav Egorov a9ce969e53 [vm] Decouple growable_array.h and zone.h from thread.h
- Introduce a slimmed down version of thread.h, which just depends on the
Zone and StackResource.
- Introduce a layering check that would prevent the coupling in the future.

This is the first step towards decoupling compiler from runtime.

There are multiple reasons to introduce the decoupling but the main
reason currently is to introduce a controlled surface through which
compiler reaches into runtime to catch any places where runtime word size
might influence the compiler and then enable building compiler that
targets 32-bit runtime but is embedded into a 64-bit runtime.

Issue https://github.com/dart-lang/sdk/issues/31709

Change-Id: Id63ebbaddca55dd097298e51c90d957a73fa476e
Reviewed-on: https://dart-review.googlesource.com/c/87182
Commit-Queue: Vyacheslav Egorov <vegorov@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
2019-01-11 20:47:10 +00:00
Ryan Macnak 3e8b335af8 [vm] Adjust concurrent marker to re-enable code W^X.
Take 2: account for encountering Instructions in the write barrier.

Bug: https://github.com/dart-lang/sdk/issues/34002
Change-Id: I31a8fc8965042678a861a05b09070d52fa07e4a5
Reviewed-on: https://dart-review.googlesource.com/c/87082
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
2018-12-14 02:02:54 +00:00
Martin Kustermann ab6eb9332f [VM] Fix flaky crash when unwinding the mutator stack during GC
The mutator thread structure is kept alive until the death of the
isolate.  Yet the mutator thread does not have to be scheduled all the
time.  A native call, for example, can suspend the isolate via
Dart_ExitIsolate to perform other work.

This particular flaky crash had precisely this problem: The mutator
thread suspended itself with an IsolateSaver scope (which uses Dart_ExitIsolate)
and invoked Dart_NewNativePort.  While at the same time the background
compiler for that isolate triggered an oldspace allocation, which
triggered a marking task.  The marker task needs to traverses the mutator
stack and hits a frame with a deoptimization marker, which causes it to
access the mutator thread's isolate pointer, which was incorrectly NULL.

Fixes https://github.com/dart-lang/sdk/issues/34748
Fixes https://github.com/dart-lang/sdk/issues/34323

Change-Id: I80440856f72b3c194a516084ddc254b2e56740d8
Reviewed-on: https://dart-review.googlesource.com/c/80860
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
2018-10-19 19:35:25 +00:00
Ryan Macnak 93dcfaa289 [vm, gc] Concurrent marking.
Fall back to parallel marking
 - on IA32 (barrier unimplemented)
 - when write_protect_code is enabled (protection dependency on marking state unimplemented)

Bug: https://github.com/dart-lang/sdk/issues/34002
Change-Id: If093f24e4dc6bf29f407cc45e95bb2274fc53dcf
Reviewed-on: https://dart-review.googlesource.com/71389
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
2018-09-21 21:30:33 +00:00
Ryan Macnak bfd86e5b22 [vm, gc] Make bypass_safepoints on helper threads sticky.
Allows concurrent marking and sweeping to continue during safepoints. However, the sweeper still cannot make much progress during a scavenge due to the scavenger holding the freelist lock.

Bug: https://github.com/dart-lang/sdk/issues/34002
Change-Id: I84f3f48feb81e8eeb67c418e918a6e12aa3178c9
Reviewed-on: https://dart-review.googlesource.com/70900
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
2018-08-21 20:12:23 +00:00
Martin Kustermann 35b17f3730 [VM] Consistently use ValidationPolicy in frame iteration APIs
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>
2018-06-04 14:46:26 +00:00
Zachary Anderson 6cd8a79078 VM: Re-format to use at most one newline between functions
R=asiva@google.com

Review-Url: https://codereview.chromium.org/2974233002 .
2017-07-13 08:08:37 -07:00
Ben Konyi 2a20b0433d Fix for issue #28606. Removed loop which iterated over all threads in the thread registry to check if a handle is valid and replaced it with a single check with the current thread.
BUG=
R=johnmccutchan@google.com

Review-Url: https://codereview.chromium.org/2672833003 .
2017-02-02 15:09:05 -08:00
Ben Konyi de72bf4991 Moved isolate high watermark calculations into the Observatory client.
BUG=
R=johnmccutchan@google.com

Review-Url: https://codereview.chromium.org/2656723002 .
2017-01-25 15:03:42 -08:00
Ben Konyi 259c7ac2be Resolution for issue #5092: Unit test handle checks consider dangling handles to be valid.
Updated the IS_VALID(handle) macro to also check if the handle is still in
scope or is a read-only handle.

BUG=
R=asiva@google.com

Review-Url: https://codereview.chromium.org/2640573003 .
2017-01-20 15:50:15 -08:00
Ben Konyi 4024151adb Added isolate + thread high watermark tracking to Observatory
This is a fixed version of c84f30741c90d040254767ff769a40d2cba3fb1a that
resolves issues with comparing uint and intptr_t.

Original Commit Message:
Added tracking of memory usage inside of threads. In addition, the max memory usage is kept track of using a high watermark for both the threads and the isolates. Isolate high watermark information is updated when a thread exits the isolate. The isolate high watermark consists of the sum of all thread high watermarks (including the high watermark of the exiting thread). High watermark information for both threads and isolates is now visible in the isolate view in the Observatory.

BUG=
R=johnmccutchan@google.com

Review-Url: https://codereview.chromium.org/2610253002 .
2017-01-05 14:24:53 -08:00
Ben Konyi ffda801791 Revert "Added isolate + thread high watermark tracking to Observatory"
This reverts commit c84f30741c90d040254767ff769a40d2cba3fb1a.

TBR=johnmccutchan@google.com

BUG=

Review-Url: https://codereview.chromium.org/2617513004 .
2017-01-04 15:21:35 -08:00
Ben Konyi b3c55f972f Added isolate + thread high watermark tracking to Observatory
Added tracking of memory usage inside of threads. In addition, the max memory usage is kept track of using a high watermark for both the threads and the isolates. Isolate high watermark information is updated when a thread exits the isolate. The isolate high watermark consists of the sum of all thread high watermarks (including the high watermark of the exiting thread). High watermark information for both threads and isolates is now visible in the isolate view in the Observatory.

BUG=
R=johnmccutchan@google.com

Review-Url: https://codereview.chromium.org/2609253002 .
2017-01-04 15:08:02 -08:00
Ben Konyi 82cf4cc374 Added methods to surface number of zone and scoped handles for each isolate.
Added methods to surface number of zone and scoped handles in each isolate. These values are displayed in the isolate view page in the Observatory. These handle counts for the native IO isolate will be surfaced in another CL.

BUG=
R=asiva@google.com

Review-Url: https://codereview.chromium.org/2601153002 .
2017-01-03 12:21:16 -08:00
Ben Konyi e28b3e3c60 Revert "Added isolate + thread high watermark tracking to Observatory"
This reverts commit 0a1a534fd9.

BUG=
R=asiva@google.com

Review-Url: https://codereview.chromium.org/2605933003 .
2016-12-28 16:49:47 -08:00
Ben Konyi 0a1a534fd9 Added isolate + thread high watermark tracking to Observatory
Added tracking of memory usage inside of threads. In addition, the max memory usage is kept track of using a high watermark for both the threads and the isolates. Isolate high watermark information is updated when a thread exits the isolate. The isolate high watermark consists of the sum of all thread high watermarks (including the high watermark of the exiting thread). High watermark information for both threads and isolates is now visible in the isolate view in the Observatory.

BUG=
R=asiva@google.com

Review-Url: https://codereview.chromium.org/2608463002 .
2016-12-28 14:59:22 -08:00
Ben Konyi 35a49bc1ff Created methods to surface zone memory information for each isolate and thread in JSON.
BUG=
R=asiva@google.com, johnmccutchan@google.com, zra@google.com

Review URL: https://codereview.chromium.org/2554983002 .
2016-12-12 09:56:49 -08:00
Srdjan Mitrovic dda658f48a Restructure/fix thread pointer visiting; added some asserts.
BUG=
R=asiva@google.com

Review URL: https://codereview.chromium.org/1814853005 .
2016-03-17 13:25:46 -07:00
Srdjan Mitrovic 24fc2a53d2 Clear reusable handles of helper threads as well. Visit mutator_thread_ even if it is not active (api_handles_ could be still alive).
BUG=
R=asiva@google.com

Review URL: https://codereview.chromium.org/1806093002 .
2016-03-16 13:43:49 -07:00
Siva Annamalai e72c1fb47d Implement safepointing of threads :
- uses thread execution status transition to track when a thread is in a safepoint or needs to block for a safepoint
 - introduces a monitor per Thread object
 - uses a per thread safepoint handshake between the thread requesting a safepoint and the requested thread.

The ThreadRegistry class now contains only the thread list for an isolate and the functionality of scheduling a thread onto an Isolate and unscheduling it from teh isolate. We could fold this functionality into the Isolate class in a different CL.

R=rmacnak@google.com, zra@google.com

Review URL: https://codereview.chromium.org/1541073002 .
2016-02-01 10:57:34 -08:00
Siva Annamalai b40775549f Fix for issue 25236
- Ensure that no new OSThreads are created once the VM is in shutdown mode
- Do not query thread_list_head_ without a lock (this leads to the race which causes two threads to delete the lock and TLS at the same time)

BUG=25236
R=zra@google.com

Review URL: https://codereview.chromium.org/1537543002 .
2015-12-18 10:16:28 -08:00
Ivan Posva e47ac24c79 - Make sure to prepare all threads for GC.
BUG=
R=asiva@google.com, srdjan@google.com

Review URL: https://codereview.chromium.org/1533023002 .
2015-12-17 19:59:13 -08:00
Siva Annamalai e2f9217dc0 Remove and Add the mutator thread from the active thread list when unscheduling and scheduling the thread on an isolate, this ensures that we do not extra count the mutator thread even after it is unscheduled during safepoint operation.
R=srdjan@google.com

Review URL: https://codereview.chromium.org/1532643003 .
2015-12-16 12:43:48 -08:00
Florian Schneider d9b1301821 VM: Fix crash in profile signal handler.
The profile signal handler may interrupt when the current Thread
is in an inconsistent state.

Members of the Thread that is unscheduled are NULLed out before
OSThread::SetCurrent sets a new current Thread. Fix this by resetting
the current Thread's fields after a new Thread is set as current.

BUG=#25702
R=iposva@google.com

Review URL: https://codereview.chromium.org/1491283002 .
2015-12-03 22:00:24 +01:00
Siva Annamalai 01b69ebabc Move ApiLocalScope out of class ApiState into class Thread so that the API local handles and zone etc. are thread specific instead of being Isolate specific.
R=zra@google.com

Review URL: https://codereview.chromium.org/1473403003 .
2015-11-25 11:07:22 -08:00
Siva Annamalai 9e19d236ca - Add an OSThread structure which is the generic TLS structure for all C++
fields in a thread (i.e fields that are not Dart VM related)
- Split the Thread structure to be a pure Dart per thread structure and add
  a pointer to os_thread which points to the OSThread structure
- Change Schedule/UnSchedule to set the Dart Thread structure as the TLS of
  the thread when it is inside the Dart world and reset the TLS back to the
  OSThread strcuture when is exits the Dart World.
- Moved the stack_base and few stack size related functions to OSThread from Isolate

R=johnmccutchan@google.com, zra@google.com

Review URL: https://codereview.chromium.org/1439483003 .
2015-11-19 13:45:10 -08:00
Siva Annamalai 5e4a3d7a65 Add IsMutatorThread to the Thread class and use it instead of MutatorThreadIsCurrentThread
Review URL: https://codereview.chromium.org/1408923005 .
2015-10-26 13:12:10 -07:00
John McCutchan da946fbf99 Simplify timeline backend
Now that we have a central list of all threads that are interacting with the VM we can stop relying on the Isolate's thread registry to cache timeline blocks.

- Move from caching blocks in the Isolate's thread registry and caching them in the Thread directly.
- This allows cached blocks to have events from multiple isolates, increasing usage density and reducing the number of blocks being cached at any given time.
- We no longer need a distinct global block, this allows me to remove a bunch of dead code.

R=turnidge@google.com

Review URL: https://codereview.chromium.org/1402383003 .
2015-10-16 13:36:58 -07:00
John McCutchan db3421ecfc Make TimelineEventBlocks reclaimable
- Add Timeline::ReclaimAllBlocks and Timeline::ReclaimIsolateBlocks utility functions to ensure that all cached blocks are closed before reporting the timeline
- Adjust Timeline_Dart_GlobalTimelineGetTrace to exercise block reclaiming
- Add ability to reclaim blocks from threads entered into an isolate
- Fix IsolateTimelineEventFilter to actually filter out open blocks
- Make some existing tests call Timeline::ReclaimIsolateBlocks before reporting
- Added implementation and locking notes to timeline.cc

R=turnidge@google.com

Review URL: https://codereview.chromium.org//1363033003 .
2015-09-24 11:32:21 -07:00
John McCutchan fe548c4bcd Add --timing
- Dump per thread timing information when an isolate shuts down.

DeltaBlue(RunTime): 3654.6660583941607 us.
Timing for isolate DeltaBlue.dart$main-109078706 (from 2 threads)

Thread 0 (f68f8b40):
HandleMessage : 2163.455 ms total on stack; 940.038 ms total executing; 2114.231 ms max on stack; 930.085 ms max executing.
CompileFunction : 81.020 ms total on stack; 81.020 ms total executing; 7.745 ms max on stack; 7.745 ms max executing.
CompileOptimizedFunction : 109.817 ms total on stack; 109.817 ms total executing; 10.443 ms max on stack; 10.443 ms max executing.
CollectNewGeneration : 1032.580 ms total on stack; 1032.580 ms total executing; 7.677 ms max on stack; 7.677 ms max executing.

Thread 1 (f7419700):
InitializeIsolate : 12.121 ms total on stack; 0.418 ms total executing; 12.121 ms max on stack; 0.418 ms max executing.
ObjectStore::Init : 0.002 ms total on stack; 0.002 ms total executing; 0.002 ms max on stack; 0.002 ms max executing.
Object::Init : 0.268 ms total on stack; 0.268 ms total executing; 0.268 ms max on stack; 0.268 ms max executing.
IsolateSnapshotReader : 11.433 ms total on stack; 11.433 ms total executing; 11.433 ms max on stack; 11.433 ms max executing.
CompileFunction : 111.849 ms total on stack; 111.849 ms total executing; 10.798 ms max on stack; 10.704 ms max executing.

Totals:
HandleMessage : 2163.455 ms total on stack; 940.038 ms total executing; 2114.231 ms max on stack; 930.085 ms max executing.
CompileFunction : 192.869 ms total on stack; 192.869 ms total executing; 10.798 ms max on stack; 10.704 ms max executing.
CompileOptimizedFunction : 109.817 ms total on stack; 109.817 ms total executing; 10.443 ms max on stack; 10.443 ms max executing.
CollectNewGeneration : 1032.580 ms total on stack; 1032.580 ms total executing; 7.677 ms max on stack; 7.677 ms max executing.
InitializeIsolate : 12.121 ms total on stack; 0.418 ms total executing; 12.121 ms max on stack; 0.418 ms max executing.
ObjectStore::Init : 0.002 ms total on stack; 0.002 ms total executing; 0.002 ms max on stack; 0.002 ms max executing.
Object::Init : 0.268 ms total on stack; 0.268 ms total executing; 0.268 ms max on stack; 0.268 ms max executing.
IsolateSnapshotReader : 11.433 ms total on stack; 11.433 ms total executing; 11.433 ms max on stack; 11.433 ms max executing.

R=rmacnak@google.com

Review URL: https://codereview.chromium.org//1296353002 .
2015-09-10 09:31:16 -07:00
John McCutchan 664742f016 Completely remove InterruptableThreadState
- InterruptableThreadState is gone.
- Moved InterruptableThreadState fields directly into Thread.
- Iterate over all threads in an isolate when profiling.
- Still only sample the mutator thread.

Fix ThreadRegistry leak

- When deleting a Thread, iterate over all isolates and remove it from the isolate's thread registry.

R=iposva@google.com

Review URL: https://codereview.chromium.org//1293253005 .
2015-08-20 14:38:38 -07:00
John McCutchan 1ff7144c31 Switch to a VM wide timeline recorder
- Initialize and shutdown timeline recorder with VM.
- Allocate global blocks for timeline events without an isolate.
- Stop storing the Stream pointer inside a TimelineEvent.
- Store category name in TimelineEvent.
- Store isolate pointer in TimelineEvent.
- TimelineEventRecorder::WriteTo is full VM dump.
- Allow JSONStream to be used without an isolate.
- When a ThreadRegistry is deleted, Finish all open timeline blocks.
- PrintJSON takes a filter.

R=rmacnak@google.com

Review URL: https://codereview.chromium.org//1294023009 .
2015-08-18 15:18:02 -07:00
Daniel Andersson 7d82391e89 Fix race and limit access to mutator_thread_.
Unsynchronized access to the contents of another thread is dangerous, even for just ASSERTs, as shown by issue 23958.

Verify the bidirectional Isolate<->Thread pointer invariant when *setting* the mutator_thread_ field, and
limit the interface to comparisons with NULL and the current thread.

BUG=https://github.com/dart-lang/sdk/issues/23958
R=johnmccutchan@google.com

Review URL: https://codereview.chromium.org//1260283007 .
2015-08-04 13:30:50 -07:00
Daniel Andersson 0897409f59 Allow threads to exit an isolate during rendezvous.
The state is saved and will be visited, so this is safe.

Also clarify that nested calls to SafepointThreads from the same thread is not supported, and check for this.

BUG=
R=iposva@google.com

Review URL: https://codereview.chromium.org//1271773003 .
2015-08-04 09:30:08 -07:00
Daniel Andersson 500eb6d79d Safepoint interface and unit tests.
Add infrastructure to enable all threads in an isolate to rendezvous at GC-safe points, and exercise it through unit tests.

* Use existing interrupt mechanism for Dart threads, but a cooperative approach for non-Dart threads (concurrent compiler, etc.): they must periodically call CheckSafepoint (may block).

* Add unit tests to exercise and verify various scenarios: organizing the rendezvous from helper/main thread, with/without Dart code executing, etc.

The next step is to use this interface in old-space allocation and garbage collection, respectively, to allow helper threads to perform allocations that potentially trigger GC (needed for concurrent compiler).

Limitations:

* A thread that is executing a long-running native function is currently not considered at a safepoint, and will delay the rendezvous until it returns to Dart or indirectly calls CheckSafepoint. In a future CL, we can use the saved stack pointer to detect and support this case, and intercept the thread if/when it re-enters Dart or the VM.

BUG=
R=iposva@google.com

Review URL: https://codereview.chromium.org//1259223005 .
2015-07-31 19:53:14 -07:00