Running dart code on mutator thread outside of isolate still should follow limits on number of concurrent mutators in the vm.
Also this fixes inconsistency when entering isolate group as mutator, where original worker was marked as blocked while thread was actually running dart code. That inconsitency showed up as sporadic crash on isolate_group_shared_init_test with increased number of spawned isolates.
TEST=isolate_group_shared_init_test
BUG=https://github.com/dart-lang/sdk/issues/60877
Change-Id: I8917be903bb5517940dad3e5dab143d5ed5fdf79
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/432900
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Alexander Aprelev <aam@google.com>
Add a mutex to guard execution of vm:shared field initialization.
TEST=isolate_group_shared_init_test
BUG=dartbug.com/60699
Change-Id: If544351fc26bfcc7fb9703954efe785989d488bc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/431742
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Write barrier elimination applies when there is no potential Dart call between a StoreFieldInstr and an AllocateObjectInstr. But the control flow between all potentially throwing instructions in a try block and the corresponding catch block is not explicitly repreresented in the flow graph, so the writer barrier elimination pass needs to handle catch entries specially.
TEST=vm/dart/write_barrier_catch_entry_test
Bug: https://github.com/dart-lang/sdk/issues/60836
Change-Id: I96d5999433320e87da095f85e4a7438bcf5e134f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/432880
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Factor out the .eh_frame section content generation from ElfWriter,
putting in as a static method in Dwarf instead.
Create a __eh_frame section in the __TEXT section of non-MacOS Mach-O
snapshots with the same information as .eh_frame in ELF snapshots.
TEST=ci
Issue: https://github.com/dart-lang/sdk/issues/60307
Change-Id: I4e123f586e59e1263385c838b755c1575a6330eb
Cq-Include-Trybots: luci.dart.try:vm-aot-linux-debug-x64-try,vm-mac-release-arm64-try,vm-aot-mac-release-arm64-try,vm-aot-mac-release-x64-try,vm-aot-dwarf-linux-product-x64-try,vm-linux-debug-x64-try,vm-mac-debug-arm64-try,vm-fuchsia-release-x64-try,vm-fuchsia-release-arm64-try,vm-linux-debug-ia32-try,vm-aot-linux-debug-simarm_x64-try,vm-aot-linux-debug-simriscv32-try,vm-aot-linux-debug-simriscv64-try,vm-aot-linux-release-simarm_x64-try,vm-gcc-linux-try,vm-ubsan-linux-release-arm64-try,vm-aot-win-release-arm64-try,vm-aot-win-release-x64-try,vm-win-release-x64-try,vm-win-release-arm64-try,vm-aot-win-debug-arm64-try,vm-win-debug-arm64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/431600
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
Adds a Mach-O loader, similar to the existing ELF loader, that
can be used on platforms that do not support loading Mach-O dynamic
libraries via dlopen().
Other changes:
* Renames the --force-load-elf-from-memory command line argument
to --force-load-from-memory.
* Use CPU_TYPE_ANY and CPU_SUBTYPE_ANY for architectures that do
not have specific constants in <mach/machine.h> (e.g., RISCV),
as the snapshot header check after loading also catches architecture
mismatches.
* Emit the unwinding information at the end of the text segment
for Windows Mach-O snapshots as is done for ELF ones.
TEST=vm/dart/unobfuscated_static_symbols_test
vm/dart/use_dwarf_stack_traces_flag_test
Issue: https://github.com/dart-lang/sdk/issues/60307
Change-Id: I34a2a334f47d18d5c4f4a712956e71fd0ac94024
Cq-Include-Trybots: luci.dart.try:vm-aot-linux-debug-x64-try,vm-mac-release-arm64-try,vm-aot-mac-release-arm64-try,vm-aot-mac-release-x64-try,vm-aot-dwarf-linux-product-x64-try,vm-linux-debug-x64-try,vm-mac-debug-arm64-try,vm-fuchsia-release-x64-try,vm-fuchsia-release-arm64-try,vm-linux-debug-ia32-try,vm-aot-linux-debug-simarm_x64-try,vm-aot-linux-debug-simriscv32-try,vm-aot-linux-debug-simriscv64-try,vm-aot-linux-release-simarm_x64-try,vm-gcc-linux-try,vm-ubsan-linux-release-arm64-try,vm-aot-win-release-arm64-try,vm-aot-win-release-x64-try,vm-win-release-x64-try,vm-win-release-arm64-try,vm-aot-win-debug-arm64-try,vm-win-debug-arm64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/430100
Reviewed-by: Slava Egorov <vegorov@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Having forwarding tables on the Thread allows for those tables to be used in dart mutator thread running in IsolateGroup-shared context. On 32-bit platforms(arm) the forwarding tables are used during [SendPort.send] message verification.
Fixes https://github.com/dart-lang/sdk/issues/60817
TEST=isolate_group_shared_send_test
Change-Id: I58b33c14026584330b594776e812fe1d48bc2fd5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/431942
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Alexander Aprelev <aam@google.com>
Use a combination of gen_snapshot's new ability to generate dylibs directly and the copy of llvm in buildtools to avoid using XCode, which is not available in shards.
Add definitions for debug builders now that they can complete without timing out.
Cq-Include-Trybots: luci.dart.try:vm-aot-mac-product-arm64-try,vm-aot-mac-release-arm64-try,vm-aot-mac-release-x64-try
Change-Id: I79924128f11aafab4cd74ea6e9ab5848c64557da
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/431700
Reviewed-by: Tess Strickland <sstrickl@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
- Reduce header surface area.
- Remove runtime_entry_<arch>.cc, which no longer include code generation.
- Fix signature of DLRT_Enter/ExitSafepoint.
- Give non-leaf runtime functions C linkage, as C++ does not have a defined ABI.
TEST=ci
Change-Id: I21e21a50ad9e4f9b32b1204d755bfa69a2ae9b17
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/430981
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
This is a reland of commit 38ef28a058
Fixes:
* Fix comparisons in ASSERT_EQUAL statements on 32-bit architectures.
* Take simulated architectures into account when deciding whether
to use dlopen() for native shared object formats.
* Fix struct/field name collision for GCC.
* Use CPU_TYPE_ANY/CPU_SUBTYPE_ANY for architectures that do not
have more specific cpu_type_t/cpu_subtype_t constants defined.
Original change's description:
> [vm, gen_snapshot] Add app-aot-macho-dylib option for AOT snapshots.
>
> This is the initial framework for creating snapshots as Mach-O dynamic
> libraries. Note that this framework is not 100% feature complete
> compared to generating Mach-O snapshots via assembly. In particular,
> the directly-compiled Mach-O dylib does not yet contain compact
> unwinding information.
>
> Other changes:
>
> * Adds UuidCommand to the native_stack_traces package's Mach-O reader,
> which now appropriately returns the UUID as the build ID for Mach-O
> shared objects.
>
> * Adds Utils::Basename(path) for portably retrieving the basename
> from a path. (Returns nullptr for all arguments where it is not
> currently implemented on Fuchsia or Windows.)
>
> * Adjusts vm/timeline.h to avoid pulling in <mach_o/loader.h> on MacOS,
> as that interferes with uses of the namespaced Mach-O definitions
> in platform/mach_o.h.
>
> * Only attempt to dlopen() a snapshot if ELF is the native format
> for the host platform or the snapshot is not an ELF shared object.
> If dlopen() is used, report the error message if it fails rather
> than attempting to manually load the snapshot as an ELF shared object.
>
> * Fix the magic number stored in DylibAppSnapshot for loaded non-ELF
> dynamic libraries.
>
> * Remove the detection of reverse-endian Mach-O magic numbers in
> DartUtils::SniffForMagicNumber(), since all our Mach-O related code
> assumes host-endian Mach-O files and so there's no point other than
> to give a slightly better error message when failing.
>
> TEST=vm/dart/exported_symbols_test
> vm/dart/unobfuscated_static_symbols_test
> vm/dart/use_dwarf_stack_traces_flag_test
> vm/cc/CanDetectMachOFiles
>
> Issue: https://github.com/dart-lang/sdk/issues/60307
> Change-Id: Idf5b49d6c6d035ab033509613212b95520d65965
> Cq-Include-Trybots: luci.dart.try:vm-aot-linux-debug-x64-try,vm-mac-release-arm64-try,vm-aot-mac-release-arm64-try,vm-aot-mac-release-x64-try,vm-aot-dwarf-linux-product-x64-try,vm-linux-debug-x64-try,vm-mac-debug-arm64-try,vm-fuchsia-release-x64-try,vm-fuchsia-release-arm64-try
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/415020
> Reviewed-by: Slava Egorov <vegorov@google.com>
> Commit-Queue: Tess Strickland <sstrickl@google.com>
TEST=vm/dart/exported_symbols_test
vm/dart/unobfuscated_static_symbols_test
vm/dart/use_dwarf_stack_traces_flag_test
vm/cc/CanDetectMachOFiles
ci on trybots that failed on the original CL
Cq-Include-Trybots: luci.dart.try:vm-aot-linux-debug-x64-try,vm-mac-release-arm64-try,vm-aot-mac-release-arm64-try,vm-aot-mac-release-x64-try,vm-aot-dwarf-linux-product-x64-try,vm-linux-debug-x64-try,vm-mac-debug-arm64-try,vm-fuchsia-release-x64-try,vm-fuchsia-release-arm64-try,vm-linux-debug-ia32-try,vm-aot-linux-debug-simarm_x64-try,vm-aot-linux-debug-simriscv32-try,vm-aot-linux-debug-simriscv64-try,vm-aot-linux-release-simarm_x64-try,vm-gcc-linux-try,vm-ubsan-linux-release-arm64-try
Change-Id: Iaffea0ddc6173100c8b5b2a9fe46c45f4f611a2e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/431240
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
This reverts commit 38ef28a058.
Reason for revert: Breaks build on debug mode 32-bit arches,
release mode simarm_x64
Issue: https://github.com/dart-lang/sdk/issues/60307
Original change's description:
> [vm, gen_snapshot] Add app-aot-macho-dylib option for AOT snapshots.
>
> This is the initial framework for creating snapshots as Mach-O dynamic
> libraries. Note that this framework is not 100% feature complete
> compared to generating Mach-O snapshots via assembly. In particular,
> the directly-compiled Mach-O dylib does not yet contain compact
> unwinding information.
>
> Other changes:
>
> * Adds UuidCommand to the native_stack_traces package's Mach-O reader,
> which now appropriately returns the UUID as the build ID for Mach-O
> shared objects.
>
> * Adds Utils::Basename(path) for portably retrieving the basename
> from a path. (Returns nullptr for all arguments where it is not
> currently implemented on Fuchsia or Windows.)
>
> * Adjusts vm/timeline.h to avoid pulling in <mach_o/loader.h> on MacOS,
> as that interferes with uses of the namespaced Mach-O definitions
> in platform/mach_o.h.
>
> * Only attempt to dlopen() a snapshot if ELF is the native format
> for the host platform or the snapshot is not an ELF shared object.
> If dlopen() is used, report the error message if it fails rather
> than attempting to manually load the snapshot as an ELF shared object.
>
> * Fix the magic number stored in DylibAppSnapshot for loaded non-ELF
> dynamic libraries.
>
> * Remove the detection of reverse-endian Mach-O magic numbers in
> DartUtils::SniffForMagicNumber(), since all our Mach-O related code
> assumes host-endian Mach-O files and so there's no point other than
> to give a slightly better error message when failing.
>
> TEST=vm/dart/exported_symbols_test
> vm/dart/unobfuscated_static_symbols_test
> vm/dart/use_dwarf_stack_traces_flag_test
> vm/cc/CanDetectMachOFiles
>
> Issue: https://github.com/dart-lang/sdk/issues/60307
> Change-Id: Idf5b49d6c6d035ab033509613212b95520d65965
> Cq-Include-Trybots: luci.dart.try:vm-aot-linux-debug-x64-try,vm-mac-release-arm64-try,vm-aot-mac-release-arm64-try,vm-aot-mac-release-x64-try,vm-aot-dwarf-linux-product-x64-try,vm-linux-debug-x64-try,vm-mac-debug-arm64-try,vm-fuchsia-release-x64-try,vm-fuchsia-release-arm64-try
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/415020
> Reviewed-by: Slava Egorov <vegorov@google.com>
> Commit-Queue: Tess Strickland <sstrickl@google.com>
Issue: https://github.com/dart-lang/sdk/issues/60307
Cq-Include-Trybots: luci.dart.try:vm-aot-linux-debug-x64-try,vm-mac-release-arm64-try,vm-aot-mac-release-arm64-try,vm-aot-mac-release-x64-try,vm-aot-dwarf-linux-product-x64-try,vm-linux-debug-x64-try,vm-mac-debug-arm64-try,vm-fuchsia-release-x64-try,vm-fuchsia-release-arm64-try
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: Iff2ab4c84a513a184784129f456bd357ae8e3a67
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/431220
Commit-Queue: Slava Egorov <vegorov@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Tess Strickland <sstrickl@google.com>
This is the initial framework for creating snapshots as Mach-O dynamic
libraries. Note that this framework is not 100% feature complete
compared to generating Mach-O snapshots via assembly. In particular,
the directly-compiled Mach-O dylib does not yet contain compact
unwinding information.
Other changes:
* Adds UuidCommand to the native_stack_traces package's Mach-O reader,
which now appropriately returns the UUID as the build ID for Mach-O
shared objects.
* Adds Utils::Basename(path) for portably retrieving the basename
from a path. (Returns nullptr for all arguments where it is not
currently implemented on Fuchsia or Windows.)
* Adjusts vm/timeline.h to avoid pulling in <mach_o/loader.h> on MacOS,
as that interferes with uses of the namespaced Mach-O definitions
in platform/mach_o.h.
* Only attempt to dlopen() a snapshot if ELF is the native format
for the host platform or the snapshot is not an ELF shared object.
If dlopen() is used, report the error message if it fails rather
than attempting to manually load the snapshot as an ELF shared object.
* Fix the magic number stored in DylibAppSnapshot for loaded non-ELF
dynamic libraries.
* Remove the detection of reverse-endian Mach-O magic numbers in
DartUtils::SniffForMagicNumber(), since all our Mach-O related code
assumes host-endian Mach-O files and so there's no point other than
to give a slightly better error message when failing.
TEST=vm/dart/exported_symbols_test
vm/dart/unobfuscated_static_symbols_test
vm/dart/use_dwarf_stack_traces_flag_test
vm/cc/CanDetectMachOFiles
Issue: https://github.com/dart-lang/sdk/issues/60307
Change-Id: Idf5b49d6c6d035ab033509613212b95520d65965
Cq-Include-Trybots: luci.dart.try:vm-aot-linux-debug-x64-try,vm-mac-release-arm64-try,vm-aot-mac-release-arm64-try,vm-aot-mac-release-x64-try,vm-aot-dwarf-linux-product-x64-try,vm-linux-debug-x64-try,vm-mac-debug-arm64-try,vm-fuchsia-release-x64-try,vm-fuchsia-release-arm64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/415020
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
Attempting to use the native definition when available causes problems
when cross-compiling, and the original attempts to avoid this broke in
subtle ways. Instead, just make a non-native definition that mimics
the native definition and use that with reinterpret_casts when sending
uses of the non-native definition to Windows API calls that expect
a value of the native definition.
TEST=windows ci
Fixes: https://github.com/dart-lang/sdk/issues/60771
Change-Id: I347fcaf8cccd809a3d8e6f041cc7e360b0b8226e
Cq-Include-Trybots: luci.dart.try:vm-aot-win-release-arm64-try,vm-aot-win-release-x64-try,vm-win-release-arm64-try,vm-win-release-x64-try,vm-aot-win-debug-arm64-try,vm-aot-win-debug-x64-try,pkg-win-release-try,pkg-win-release-arm64-try,dart-sdk-win-try,dart-sdk-win-arm64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/430400
Reviewed-by: Slava Egorov <vegorov@google.com>
With b32e5e5a91 under --experimental_shared_data flag, `LoadStaticField` calls initializer stub to confirm presence of isolate when accessing non-shared static fields. This breaks the role that `calls_initializer` attribute/parameter used to play where it was specifically describing neccessity to call initializer, which is important in how `LoadStaticField` instruction is used in static field setters - it should not attempt to call initialzer.
This CL fixes the problem by renaming current `calls_initializer` `LoadStaticFieldInstr` attribute to `does_slow_checks`, and "adding" separate `calls_initializer` parameter to the instruction to signify specifically whether initializer has to be called.
TEST=ci
Change-Id: Ib81424864c98d889fb6dbb9dd15dac9a39c530f8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/429062
Reviewed-by: Slava Egorov <vegorov@google.com>
Fix the following compile-time errors:
C:\b\s\w\ir\cache\builder\sdk\runtime\vm\elf.cc(601) : error C2220: the following warning is treated as an error
C:\b\s\w\ir\cache\builder\sdk\runtime\vm\elf.cc(601) : warning C4715: 'dart::ElfSymbolTable::ElfSymbolType': not all control paths return a value
../../runtime/vm/elf.cc: In static member function ‘static intptr_t dart::ElfSymbolTable::ElfSymbolType(dart::SharedObjectWriter::SymbolData::Type)’:
../../runtime/vm/elf.cc:601:3: error: control reaches end of non-void function [-Werror=return-type]
601 | }
| ^
TEST=ci
Change-Id: Ib06339405b406ea4a6f6d395a04a16573d92c704
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/430321
Auto-Submit: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Alexander Aprelev <aam@google.com>
This CL pulls out the refactorings used to support the new MachOWriter
in a followup CL to allow them to be reviewed separately.
Rename Elf -> ElfWriter. Also rename model classes used by ElfWriter
for concepts that exist both in ELF and Mach-O to ElfX. For example,
the old ELF-specific SymbolTable is renamed to ElfSymbolTable.
Adds SharedObjectWriter to serve as a base class for both ElfWriter
and the upcoming MachOWriter.
Adds a new AbstractWriteStream that serves as a common superclass
of both BaseWriteStream and SharedObjectWriter::WriteStream and
allows the creation of fully delegating WriteStreams that do not
maintain a local buffer.
Abstract the old Elf::SymbolData class into
SharedObjectWriter::SymbolData, which stores an enum value as the type
of the symbol instead of storing the ELF encoding of the type.
Rename the DwarfElfStream (which actually wasn't ELF specific, as
all the ELF-specific DWARF information is handled by ElfWriter) to
DwarfSharedObjectStream and put it in a separate header file.
Rename Image::compiled_to_elf() to Image::compiled_to_shared_object()
and add a separate Image::compiled_to_elf() that checks for the ELF
magic value at the DSO base. Also add Image::shared_object_start()
and Image::build_id_start() to return pointers to the DSO base and
the build ID note, respectively.
Refactor Image::build_id() and Image::build_id_length() to check
compiled_for_elf() prior to decoding the data pointed to by
build_id_start() as an ELF note section.
Create an AOTSnapshotType enum to specific the snapshot writer to use
in CreateAppAOTSnapshot instead of using an as_elf boolean.
TEST=refactorings, so existing tests on ci
Change-Id: Ia3ab37a4dff93b6e00390b123753be5a51fbdaaa
Cq-Include-Trybots: luci.dart.try:vm-aot-linux-debug-x64-try,vm-aot-mac-release-arm64-try,vm-aot-dwarf-linux-product-x64-try,vm-linux-debug-x64-try,vm-mac-debug-arm64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/421301
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
Instead of hiding it by skipping it in AsyncAwareStackUnwinder.
Skipping it manually meant that we don't expand and see
functions which are inlined into handleValue in the
stacktrace which might be undesirable and makes
stacktraces unnecessarily sensitive to inlining.
Filtering based on visibility happens after inlined
frame expansion which makes stack trace more stable.
Fixes https://github.com/dart-lang/sdk/issues/60684
TEST=vm/dart/awaiter_stacks/*
CoreLibraryReviewExempt: pragma only change
Cq-Include-Trybots: luci.dart.try:vm-aot-linux-release-x64-try,vm-aot-linux-product-x64-try
Change-Id: Ie6e0ad65285dd1d6f77e27e7488e8d46d30c176c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/429660
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>
This CL introduces variance-dependent treatment of the `Handle` native
type when converting native types to Dart types. Since `Handle` can
represent any object, it should match any type. To achive that in
cases when `Handle` appears as the subtype in the subtype checks, it's
converted to `Never` in covariant positions and to `Object?` in
covariant ones.
TEST=existing
Issue https://github.com/dart-lang/sdk/issues/49518
Change-Id: Ie16a210491ada80d21f4d0f1c0fa3b3804881ede
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/426880
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Commit-Queue: Chloe Stefantsova <cstefantsova@google.com>
Static (direct) calls in the optimized JIT are performed through Code
objects without passing Function objects. This is not compatible with
bytecode interpreter calling conventions, so optimized JIT should
avoid static calls to bytecode functions.
This change disables devirtualized and guarded static calls to
functions declared in bytecode.
TEST=ci
Closes https://github.com/dart-lang/sdk/issues/60716
Change-Id: I95e4fa0706f376355f4fa7aea7fddf44f303e0a0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/428340
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
TEST=pkg/vm_service/test/get_queued_microtasks_rpc_test
CoreLibraryReviewExempt: This CL does not include any core library API
changes, only VM Service implementation changes within
sdk/lib/vmservice/.
Change-Id: Ie5488f498e4d0f3d201e3f31423fd5029b74a726
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/425160
Commit-Queue: Derek Xu <derekx@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>
Ryan Macnak