Adds InterpreterCompilationJob as a sub-class of
CompilationJob, to enable off-thread bytecode
generation. Currently only used in
Interpreter::MakeBytecode.
As part of this change, CompilationJob is modified
to make it less specific to optimized compilation,
renaming the phases as follows:
- CreateGraph -> PrepareJob
- OptimizeGraph -> ExecuteJob
- GenerateCode -> FinalizeJob
RegisterWeakObjectsInOptimizedCode is also moved out
of CompilationJob and instead becomes a static function
on Compiler.
BUG=v8:5203
Committed: https://crrev.com/1fb6a7e697e8bc5b4af51647553741f966e00cdc
Committed: https://crrev.com/785990e9fc0dd9a9d963d25d0bed2909165e4ca9
Review-Url: https://codereview.chromium.org/2240463002
Cr-Original-Original-Commit-Position: refs/heads/master@{#38662}
Cr-Original-Commit-Position: refs/heads/master@{#38668}
Cr-Commit-Position: refs/heads/master@{#38725}
This fixes canonicalization of {SharedFunctionInfo} objects in the
{Compiler::GetSharedFunctionInfo} method when bytecode is preserved.
Eager compilation is only triggered when no code is present.
R=rmcilroy@chromium.org
TEST=mjsunit/regress/regress-crbug-638551
BUG=chromium:638551
Review-Url: https://codereview.chromium.org/2245263006
Cr-Commit-Position: refs/heads/master@{#38709}
Our previous per-arch instantiation thunks for asm.js
didn't support modules that had or were called with anything other
than 3 arguments. Adding support for this.
Addding a runtime test method to check if asm validation succeeded.
Adding a test of validation with different argument count combinations.
R=mstarzinger@chromium.org
TEST=mjsunit/asm/asm-validator.js
BUG= https://bugs.chromium.org/p/v8/issues/detail?id=4203
Review-Url: https://codereview.chromium.org/2229723002
Cr-Commit-Position: refs/heads/master@{#38688}
Reason for revert:
Breaks Win64 bot
Original issue's description:
> [Interpreter] Introduce InterpreterCompilationJob
>
> Adds InterpreterCompilationJob as a sub-class of
> CompilationJob, to enable off-thread bytecode
> generation. Currently only used in
> Interpreter::MakeBytecode.
>
> As part of this change, CompilationJob is modified
> to make it less specific to optimized compilation,
> renaming the phases as follows:
> - CreateGraph -> PrepareJob
> - OptimizeGraph -> ExecuteJob
> - GenerateCode -> FinalizeJob
>
> RegisterWeakObjectsInOptimizedCode is also moved out
> of CompilationJob and instead becomes a static function
> on Compiler.
>
> BUG=v8:5203
>
> Committed: https://crrev.com/1fb6a7e697e8bc5b4af51647553741f966e00cdc
> Committed: https://crrev.com/785990e9fc0dd9a9d963d25d0bed2909165e4ca9
> Cr-Original-Commit-Position: refs/heads/master@{#38662}
> Cr-Commit-Position: refs/heads/master@{#38668}
TBR=mstarzinger@chromium.org,jkummerow@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:5203
Review-Url: https://codereview.chromium.org/2251673003
Cr-Commit-Position: refs/heads/master@{#38669}
Adds InterpreterCompilationJob as a sub-class of
CompilationJob, to enable off-thread bytecode
generation. Currently only used in
Interpreter::MakeBytecode.
As part of this change, CompilationJob is modified
to make it less specific to optimized compilation,
renaming the phases as follows:
- CreateGraph -> PrepareJob
- OptimizeGraph -> ExecuteJob
- GenerateCode -> FinalizeJob
RegisterWeakObjectsInOptimizedCode is also moved out
of CompilationJob and instead becomes a static function
on Compiler.
BUG=v8:5203
Committed: https://crrev.com/1fb6a7e697e8bc5b4af51647553741f966e00cdc
Review-Url: https://codereview.chromium.org/2240463002
Cr-Original-Commit-Position: refs/heads/master@{#38662}
Cr-Commit-Position: refs/heads/master@{#38668}
Reason for revert:
Failing on Win64 bot:
https://build.chromium.org/p/client.v8/builders/V8%20Win64/builds/12061/steps/Check/logs/regress-635429
Original issue's description:
> [Interpreter] Introduce InterpreterCompilationJob
>
> Adds InterpreterCompilationJob as a sub-class of
> CompilationJob, to enable off-thread bytecode
> generation. Currently only used in
> Interpreter::MakeBytecode.
>
> As part of this change, CompilationJob is modified
> to make it less specific to optimized compilation,
> renaming the phases as follows:
> - CreateGraph -> PrepareJob
> - OptimizeGraph -> ExecuteJob
> - GenerateCode -> FinalizeJob
>
> RegisterWeakObjectsInOptimizedCode is also moved out
> of CompilationJob and instead becomes a static function
> on Compiler.
>
> BUG=v8:5203
>
> Committed: https://crrev.com/1fb6a7e697e8bc5b4af51647553741f966e00cdc
> Cr-Commit-Position: refs/heads/master@{#38662}
TBR=mstarzinger@chromium.org,jkummerow@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:5203
Review-Url: https://codereview.chromium.org/2249153002
Cr-Commit-Position: refs/heads/master@{#38663}
Adds InterpreterCompilationJob as a sub-class of
CompilationJob, to enable off-thread bytecode
generation. Currently only used in
Interpreter::MakeBytecode.
As part of this change, CompilationJob is modified
to make it less specific to optimized compilation,
renaming the phases as follows:
- CreateGraph -> PrepareJob
- OptimizeGraph -> ExecuteJob
- GenerateCode -> FinalizeJob
RegisterWeakObjectsInOptimizedCode is also moved out
of CompilationJob and instead becomes a static function
on Compiler.
BUG=v8:5203
Review-Url: https://codereview.chromium.org/2240463002
Cr-Commit-Position: refs/heads/master@{#38662}
This adds a shortcut to the compilation pipeline that makes sure we are
not regenerating bytecode when it has been preserved from a previous
request. This can happen when code flushing removes baseline code,
thereby clearing the entry trampoline but leaving bytecode intact.
R=yangguo@chromium.org
BUG=v8:5265
Review-Url: https://codereview.chromium.org/2241783002
Cr-Commit-Position: refs/heads/master@{#38620}
Should fix a performance regression introduced by introducing
a CanonicalHandleScope for bytecode compilation. Also fix a
missing CanonicalHandleScope in GetSharedFunctionInfo.
BUG=chromium:634953
Review-Url: https://codereview.chromium.org/2226923002
Cr-Commit-Position: refs/heads/master@{#38583}
This adds the --ignition-preserve-bytecode flag which will preserve any
existing bytecode, even if a tier-up to baseline code is performed. This
is preparatory work in order to allow mixed stacks where bytecode and
baseline code can be active at the same time.
It also adds a {HasBaselineCode} predicate symmetric to the existing
{HasBytecodeArray} predicate. Both predicates are independent and any
combination of answers is valid.
Further adaptation of the rest of the runtime will be done step-wise in
follow-up changes.
R=yangguo@chromium.org
BUG=v8:5265
Review-Url: https://codereview.chromium.org/2224923003
Cr-Commit-Position: refs/heads/master@{#38540}
Updates a number of AST operations to avoid dereferencing handles
such that they can safely be called off-thread. Also adds a
HandleDereferenceMode argument to some operations where handles are
compared. If handle dereferencing is allowed, the handles are compared
directly, if not then their locations are compared (which relies on the
handles being created in a CanonicalHandleScope).
BUG=v8:5203
TBR=adamk@chromium.org
Review-Url: https://codereview.chromium.org/2223523002
Cr-Commit-Position: refs/heads/master@{#38526}
Currently we have V8 RuntimeCallStats that is independently from tracing when
running d8 with flag --runtime_call_stats. This patch embeds V8 runtime call
stats into tracing, by having a global table of runtime call counters each
isolate, resetting the table each time we enter a top level trace event, and
dumping the table for each top level trace event. This will make trace file more
compat, as well as enable runtime call stats in tracing system.
This patch adds ~5% overhead to V8 when the category is enabled, we measure the
overhead by running a script when category is enabled.
BUG=v8:5089
Committed: https://crrev.com/d014866173eaa2b548c566217b2c94b1d49385fa
Committed: https://crrev.com/1ca3b73bba4a7253ca8eeef39321d70e7d414331
Committed: https://crrev.com/3f936a5b17754783e92d2146eaf66c88a78ee45b
Review-Url: https://codereview.chromium.org/2187693002
Cr-Original-Original-Original-Commit-Position: refs/heads/master@{#38270}
Cr-Original-Original-Commit-Position: refs/heads/master@{#38314}
Cr-Original-Commit-Position: refs/heads/master@{#38403}
Cr-Commit-Position: refs/heads/master@{#38510}
Reason for revert:
Leaks block chromium roll:
https://codereview.chromium.org/2219083003/
Example build:
https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_asan_rel_ng/builds/205435
You can add the trybot from tryserver.chromium.linux, linux_chromium_asan_rel_ng, on reland.
Original issue's description:
> [Reland][Tracing] Embed V8 runtime call stats into tracing.
>
> Currently we have V8 RuntimeCallStats that is independently from tracing when
> running d8 with flag --runtime_call_stats. This patch embeds V8 runtime call
> stats into tracing, by having a global table of runtime call counters each
> isolate, resetting the table each time we enter a top level trace event, and
> dumping the table for each top level trace event. This will make trace file more
> compat, as well as enable runtime call stats in tracing system.
>
> This patch adds ~5% overhead to V8 when the category is enabled, we measure the
> overhead by running a script when category is enabled.
>
> BUG=v8:5089
>
> Committed: https://crrev.com/d014866173eaa2b548c566217b2c94b1d49385fa
> Committed: https://crrev.com/1ca3b73bba4a7253ca8eeef39321d70e7d414331
> Committed: https://crrev.com/3f936a5b17754783e92d2146eaf66c88a78ee45b
> Cr-Original-Original-Commit-Position: refs/heads/master@{#38270}
> Cr-Original-Commit-Position: refs/heads/master@{#38314}
> Cr-Commit-Position: refs/heads/master@{#38403}
TBR=cbruni@chromium.org,fmeawad@chromium.org,bmeurer@chromium.org,adamk@chromium.org,rmcilroy@chromium.org,lpy@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=v8:5089
NOTRY=true
NOPRESUBMIT=true
Review-Url: https://codereview.chromium.org/2221853002
Cr-Commit-Position: refs/heads/master@{#38412}
Currently we have V8 RuntimeCallStats that is independently from tracing when
running d8 with flag --runtime_call_stats. This patch embeds V8 runtime call
stats into tracing, by having a global table of runtime call counters each
isolate, resetting the table each time we enter a top level trace event, and
dumping the table for each top level trace event. This will make trace file more
compat, as well as enable runtime call stats in tracing system.
This patch adds ~5% overhead to V8 when the category is enabled, we measure the
overhead by running a script when category is enabled.
BUG=v8:5089
Committed: https://crrev.com/d014866173eaa2b548c566217b2c94b1d49385fa
Committed: https://crrev.com/1ca3b73bba4a7253ca8eeef39321d70e7d414331
Review-Url: https://codereview.chromium.org/2187693002
Cr-Original-Original-Commit-Position: refs/heads/master@{#38270}
Cr-Original-Commit-Position: refs/heads/master@{#38314}
Cr-Commit-Position: refs/heads/master@{#38403}
This also gets rid of the pending_error_handler field on DeclarationScope which wasn't actually used.
BUG=v8:5209
Review-Url: https://codereview.chromium.org/2218083002
Cr-Commit-Position: refs/heads/master@{#38400}
This reduces peak zone memory usage by ~10% on codeload and ~5% on mandreel.
BUG=v8:5209
Review-Url: https://codereview.chromium.org/2209573002
Cr-Commit-Position: refs/heads/master@{#38367}
Changes ConstantPoolArrayBuilder to do object lookups using the location
of the handles, rather than dereferencing the handles and comparing the
objects. This also updates CanonicalHandleScope when internalizing AST
nodes to ensure that duplicate objects share the same handles and so are
only added to the constant pool once.
BUG=v8:5203
Review-Url: https://codereview.chromium.org/2204243003
Cr-Commit-Position: refs/heads/master@{#38366}
This makes sure we prevent a tier-up for function which also have an
optimized activation of OSR code on the stack. In case the OSR code
deoptimizes, it needs the bytecode to still be around.
R=rmcilroy@chromium.org
TEST=mjsunit/regress/regress-5262
BUG=v8:5262
Review-Url: https://codereview.chromium.org/2206363004
Cr-Commit-Position: refs/heads/master@{#38359}
Reason for revert:
Mac64 ASAN failure. https://build.chromium.org/p/client.v8/builders/V8%20Mac64%20ASAN/builds/7810/steps/Check/logs/Threading4
Original issue's description:
> [Reland][Tracing] Embed V8 runtime call stats into tracing.
>
> Currently we have V8 RuntimeCallStats that is independently from tracing when
> running d8 with flag --runtime_call_stats. This patch embeds V8 runtime call
> stats into tracing, by having a global table of runtime call counters each
> isolate, resetting the table each time we enter a top level trace event, and
> dumping the table for each top level trace event. This will make trace file more
> compat, as well as enable runtime call stats in tracing system.
>
> This patch adds ~5% overhead to V8 when the category is enabled, we measure the
> overhead by running a script when category is enabled.
>
> BUG=v8:5089
>
> Committed: https://crrev.com/d014866173eaa2b548c566217b2c94b1d49385fa
> Committed: https://crrev.com/1ca3b73bba4a7253ca8eeef39321d70e7d414331
> Cr-Original-Commit-Position: refs/heads/master@{#38270}
> Cr-Commit-Position: refs/heads/master@{#38314}
TBR=cbruni@chromium.org,fmeawad@chromium.org,machenbach@chromium.org,bmeurer@chromium.org,adamk@chromium.org,rmcilroy@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:5089
Review-Url: https://codereview.chromium.org/2200373003
Cr-Commit-Position: refs/heads/master@{#38315}
Currently we have V8 RuntimeCallStats that is independently from tracing when
running d8 with flag --runtime_call_stats. This patch embeds V8 runtime call
stats into tracing, by having a global table of runtime call counters each
isolate, resetting the table each time we enter a top level trace event, and
dumping the table for each top level trace event. This will make trace file more
compat, as well as enable runtime call stats in tracing system.
This patch adds ~5% overhead to V8 when the category is enabled, we measure the
overhead by running a script when category is enabled.
BUG=v8:5089
Committed: https://crrev.com/d014866173eaa2b548c566217b2c94b1d49385fa
Review-Url: https://codereview.chromium.org/2187693002
Cr-Original-Commit-Position: refs/heads/master@{#38270}
Cr-Commit-Position: refs/heads/master@{#38314}
Reason for revert:
Sanitizer failures:
https://build.chromium.org/p/client.v8/builders/V8%20Linux64%20TSAN/builds/10989/https://build.chromium.org/p/client.v8/builders/V8%20Mac64%20ASAN/builds/7786/
Original issue's description:
> [Tracing] Embed V8 runtime call stats into tracing.
>
> Currently we have V8 RuntimeCallStats that is independently from tracing when
> running d8 with flag --runtime_call_stats. This patch embeds V8 runtime call
> stats into tracing, by having a global table of runtime call counters each
> isolate, resetting the table each time we enter a top level trace event, and
> dumping the table for each top level trace event. This will make trace file more
> compat, as well as enable runtime call stats in tracing system.
>
> This patch adds ~5% overhead to V8 when the category is enabled, we measure the
> overhead by running a script when category is enabled.
>
> BUG=v8:5089
>
> Committed: https://crrev.com/d014866173eaa2b548c566217b2c94b1d49385fa
> Cr-Commit-Position: refs/heads/master@{#38270}
TBR=cbruni@chromium.org,fmeawad@chromium.org,machenbach@chromium.org,bmeurer@chromium.org,adamk@chromium.org,rmcilroy@chromium.org,lpy@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:5089
Review-Url: https://codereview.chromium.org/2203913004
Cr-Commit-Position: refs/heads/master@{#38275}
Currently we have V8 RuntimeCallStats that is independently from tracing when
running d8 with flag --runtime_call_stats. This patch embeds V8 runtime call
stats into tracing, by having a global table of runtime call counters each
isolate, resetting the table each time we enter a top level trace event, and
dumping the table for each top level trace event. This will make trace file more
compat, as well as enable runtime call stats in tracing system.
This patch adds ~5% overhead to V8 when the category is enabled, we measure the
overhead by running a script when category is enabled.
BUG=5089
Review-Url: https://codereview.chromium.org/2187693002
Cr-Commit-Position: refs/heads/master@{#38270}
This implements graph construction for entry via on-stack replacement
within the {BytecodeGraphBuilder}. Entry points are at loop headers
similar to previous OSR implementations. All interpreter registers are
addressable via {OsrValue} nodes in the graph. Currently we rely on
{OsrPoll} bytecodes to be placed right after loop headers (i.e. at the
targets of back edges).
R=jarin@chromium.org
BUG=v8:4764
Review-Url: https://codereview.chromium.org/2171083004
Cr-Commit-Position: refs/heads/master@{#38083}
Reason for revert:
Fix has been landed.
Original issue's description:
> Revert of [interpreter] Add explicit OSR polling bytecode. (patchset #6 id:100001 of https://codereview.chromium.org/2172233002/ )
>
> Reason for revert:
> Bunch of breakages. Maybe bad interaction with e520e5da55 ?
>
> E.g.:
> https://build.chromium.org/p/client.v8/builders/V8%20Linux64/builds/11607
>
> Original issue's description:
> > [interpreter] Add explicit OSR polling bytecode.
> >
> > This adds an explicit {OsrPoll} bytecode into every loop header which
> > triggers on-stack replacement when armed. Note that each such bytecode
> > stores the static loop depths as an operand, and hence can be armed for
> > specific loop depths.
> >
> > This also adds builtin code that triggers OSR compilation and switches
> > execution over to optimized code in case compilation succeeds. In case
> > compilation fails, the bytecode dispatch just continues unhindered.
> >
> > R=rmcilroy@chromium.org
> > TEST=mjsunit/ignition/osr-from-bytecode
> > BUG=v8:4764
> >
> > Committed: https://crrev.com/a55beb68e0ededb3773affa294a71edc50621458
> > Cr-Commit-Position: refs/heads/master@{#38043}
>
> TBR=rmcilroy@chromium.org,mstarzinger@chromium.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=v8:4764
>
> Committed: https://crrev.com/439aa2c6d708bfd95db725bd6f97c4c49bbc51fc
> Cr-Commit-Position: refs/heads/master@{#38044}
TBR=rmcilroy@chromium.org,machenbach@chromium.org
BUG=v8:4764
Review-Url: https://codereview.chromium.org/2184713002
Cr-Commit-Position: refs/heads/master@{#38056}
Reason for revert:
Bunch of breakages. Maybe bad interaction with e520e5da55 ?
E.g.:
https://build.chromium.org/p/client.v8/builders/V8%20Linux64/builds/11607
Original issue's description:
> [interpreter] Add explicit OSR polling bytecode.
>
> This adds an explicit {OsrPoll} bytecode into every loop header which
> triggers on-stack replacement when armed. Note that each such bytecode
> stores the static loop depths as an operand, and hence can be armed for
> specific loop depths.
>
> This also adds builtin code that triggers OSR compilation and switches
> execution over to optimized code in case compilation succeeds. In case
> compilation fails, the bytecode dispatch just continues unhindered.
>
> R=rmcilroy@chromium.org
> TEST=mjsunit/ignition/osr-from-bytecode
> BUG=v8:4764
>
> Committed: https://crrev.com/a55beb68e0ededb3773affa294a71edc50621458
> Cr-Commit-Position: refs/heads/master@{#38043}
TBR=rmcilroy@chromium.org,mstarzinger@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4764
Review-Url: https://codereview.chromium.org/2184553003
Cr-Commit-Position: refs/heads/master@{#38044}
This adds an explicit {OsrPoll} bytecode into every loop header which
triggers on-stack replacement when armed. Note that each such bytecode
stores the static loop depths as an operand, and hence can be armed for
specific loop depths.
This also adds builtin code that triggers OSR compilation and switches
execution over to optimized code in case compilation succeeds. In case
compilation fails, the bytecode dispatch just continues unhindered.
R=rmcilroy@chromium.org
TEST=mjsunit/ignition/osr-from-bytecode
BUG=v8:4764
Review-Url: https://codereview.chromium.org/2172233002
Cr-Commit-Position: refs/heads/master@{#38043}
Always use the BytecodeGraphBuilder when the --turbo-from-bytecode
is enabled, assuming the function should be compiled for Ignition.
Adds a new MaybeOptimizeIgnition function to runtime-profiler
which is called if the function should be optimized from bytecode
rather than going via full-codegen.
BUG=v8:4280
Committed: https://crrev.com/9ca7db914be88e6792a88eab4a1988ee031d70c4
Review-Url: https://codereview.chromium.org/2156753002
Cr-Original-Commit-Position: refs/heads/master@{#37921}
Cr-Commit-Position: refs/heads/master@{#38002}
Reason for revert:
Breaks tsan:
https://build.chromium.org/p/client.v8/builders/V8%20Linux64%20TSAN/builds/10758
Original issue's description:
> [Intepreter] Always use BytecodeGraphBuilder when --turbo-from-bytecode
>
> Always use the BytecodeGraphBuilder when the --turbo-from-bytecode
> is enabled, assuming the function should be compiled for Ignition.
> Adds a new MaybeOptimizeIgnition function to runtime-profiler
> which is called if the function should be optimized from bytecode
> rather than going via full-codegen.
>
> BUG=v8:4280
>
> Committed: https://crrev.com/9ca7db914be88e6792a88eab4a1988ee031d70c4
> Cr-Commit-Position: refs/heads/master@{#37921}
TBR=mstarzinger@chromium.org,rmcilroy@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4280
Review-Url: https://codereview.chromium.org/2165223002
Cr-Commit-Position: refs/heads/master@{#37925}
Always use the BytecodeGraphBuilder when the --turbo-from-bytecode
is enabled, assuming the function should be compiled for Ignition.
Adds a new MaybeOptimizeIgnition function to runtime-profiler
which is called if the function should be optimized from bytecode
rather than going via full-codegen.
BUG=v8:4280
Review-Url: https://codereview.chromium.org/2156753002
Cr-Commit-Position: refs/heads/master@{#37921}
This removes the fallback path in question. Now the {AstNumbering} phase
is the only phase deciding whether Crankshaft is supposed to be disabled
or not. This in turn simplifies reasoning about the paths through the
compilation pipeline. We can decide early whether we want Ignition to
kick in depending on whether Crankshaft is enabled or not.
R=mvstanton@chromium.org,rmcilroy@chromium.org
Review-Url: https://codereview.chromium.org/2146573004
Cr-Commit-Position: refs/heads/master@{#37763}
The PrettyPrinter may have been valuable once, but with all the desugaring
now done in the parser the output is far from readable, and for some nodes
it's next-to-impossible to recreate the source from the AST. --print-ast is a
much more sensible place to look for human-readable info on what the parser did.
Review-Url: https://codereview.chromium.org/1974623002
Cr-Commit-Position: refs/heads/master@{#37730}
CallSite::IsConstructor() was unable to recognize builtin construct stubs
(NumberConstructor_ConstructStub and StringConstructor_ConstructStub) as
constructors, and thus these frames were not formatted correctly in stack
traces.
Fix this by explicitly marking their Code objects as construct stubs and
passing along a special receiver value when we encounter such cases in
CaptureSimpleStackTrace.
R=mstarzinger@chromium.org, yangguo@chromium.org
BUG=
Review-Url: https://codereview.chromium.org/2125163004
Cr-Commit-Position: refs/heads/master@{#37631}
