Commit Graph

25410 Commits

Author SHA1 Message Date
adamk
7485da7ace Don't crash when preparsing destructured arguments
This adds the materialized literal count accumulated while parsing the
parameters (in the parser proper) to that accumulated by the preparser.

This should have been caught in cctest/test-parsing, but it's not covered
because the parsing tests call directly into the preparser rather than
using Parser::ParseFunctionLiteral (which fully-parses the parameters
and then calls into the preparser to skip over the function body).

Note that this further-inflates the materialized literal count for
functions with destructured arguments, since some of the counted
literals are actually binding patterns. But that's not specific to
binding patterns in formal parameters: it happens in function bodies, too.

BUG=v8:4400,v8:4407
LOG=n

Review URL: https://codereview.chromium.org/1350913005

Cr-Commit-Position: refs/heads/master@{#30868}
2015-09-22 17:43:43 +00:00
conradw
24ec2a0baa [strong] Implement revised strong class semantics
Weak classes can inherit from strong ones again, a strong base class makes
instances strong.

BUG=v8:3956
LOG=N

Review URL: https://codereview.chromium.org/1347243004

Cr-Commit-Position: refs/heads/master@{#30867}
2015-09-22 16:34:52 +00:00
neis
191a0cb6dd Make prettyprinter useful in gdb.
R=rossberg
BUG=

Review URL: https://codereview.chromium.org/1354433004

Cr-Commit-Position: refs/heads/master@{#30866}
2015-09-22 15:57:10 +00:00
mlippautz
5e08d818f0 [tools] Add script to analyze GC tracing output
BUG=

Review URL: https://codereview.chromium.org/1348763006

Cr-Commit-Position: refs/heads/master@{#30865}
2015-09-22 13:59:34 +00:00
hpayer
0bfb773de2 [heap] Process live weak cells directly in the marking visitor.
This reduces the pause time of weak cells processing during a full GC.

BUG=

Review URL: https://codereview.chromium.org/1363553002

Cr-Commit-Position: refs/heads/master@{#30864}
2015-09-22 13:48:21 +00:00
Michael Achenbach
0ee53fdd13 Whitespace change to test infra changes.
Cr-Commit-Position: refs/heads/master@{#30863}
2015-09-22 13:35:06 +00:00
Michael Achenbach
9e63a71fb9 Whitespace change to test infra changes.
Cr-Commit-Position: refs/heads/master@{#30862}
2015-09-22 13:17:07 +00:00
ishell
667c5e0140 [x64] Tweaking kMaxSizeEarlyOpt value to recover SunSpider/3d-cube.
With the IC-less global variables accesses the size of the Rotate* functions became small enough to be immediately optimized by Crankshaft which in turn tanked SunSpider/3d-cube.

BUG=chromium:531338
LOG=N

Review URL: https://codereview.chromium.org/1356603005

Cr-Commit-Position: refs/heads/master@{#30861}
2015-09-22 08:39:54 +00:00
bmeurer
10c5f2e85e [ic] Introduce BOOLEAN state for CompareIC.
Slow path for relational comparison of boolean primitive values
now goes through the runtime, which made the slow path even
slower than it already was. So in order to repair the regression,
we just track boolean feedback for comparisons and use that
to generate decent code in Crankshaft (not the best possible
code, but good enough for Crankshaft; TurboFan will be able
to do better on that).

R=jarin@chromium.org
BUG=chromium:534200
LOG=n

Review URL: https://codereview.chromium.org/1347063004

Cr-Commit-Position: refs/heads/master@{#30860}
2015-09-22 08:01:36 +00:00
bmeurer
02a2580b16 [x64] Compare map instead of value to heap number map in ToStringStub.
Fixes a typo introduced earlier, where we compare the value to heap
number map instead of the map loaded previously.

TBR=jarin@chromium.org

Review URL: https://codereview.chromium.org/1355253002

Cr-Commit-Position: refs/heads/master@{#30859}
2015-09-22 07:20:03 +00:00
bmeurer
4542a2d4cc [crankshaft] Re-add fast-case for string add left/right.
Now the StringAddStub can optionally convert it's parameters to strings
(following the rules for the addition operator). This could be further
optimized once we have a ToPrimitiveStub, but it should be sufficient
for the moment.

Also removed the unused Strength parameter to the HStringAdd operator,
because string addition does not depend on language mode.

R=jarin@chromium.org
BUG=v8:4307, chromium:532524
LOG=n

Committed: https://crrev.com/d261849e53fbf8c36efae42d478271f87acff70f
Cr-Commit-Position: refs/heads/master@{#30726}

Review URL: https://codereview.chromium.org/1339053002

Cr-Commit-Position: refs/heads/master@{#30858}
2015-09-22 05:46:46 +00:00
bmeurer
1dfac69f1f [builtins] Add support for NewTarget to Execution::New.
Introduce new builtins Construct and ConstructFunction (in line
with the Call and CallFunction builtins that we already have) as
proper bottleneck for Construct and [[Construct]] on JSFunctions.
Use these builtins to support passing NewTarget from C++ to
JavaScript land.

Long-term we want the CallConstructStub to be used for
gathering feedback on entry to construction chain (i.e. the
initial new Foo), and use the Construct builtins to do the
actual work inside the construction chain (i.e. calling into
super and stuff).

MIPS and MIPS64 ports contributed by akos.palfi@imgtec.com.

R=jarin@chromium.org
BUG=v8:4430
LOG=n

Review URL: https://codereview.chromium.org/1359583002

Cr-Commit-Position: refs/heads/master@{#30857}
2015-09-22 04:27:28 +00:00
bmeurer
3d7c45371e [crankshaft] Handle @@toStringTag accessor correctly for BuildCompareInstruction.
If @@toStringTag is an accessor property, we cannot assume that the result
of calling Object.prototype.toString() for objects with the same map.

R=adamk@chromium.org
BUG=chromium:534200
LOG=n

Review URL: https://codereview.chromium.org/1360723002

Cr-Commit-Position: refs/heads/master@{#30856}
2015-09-22 04:08:08 +00:00
v8-autoroll
9308f8f95b Update V8 DEPS.
Rolling v8/build/gyp to 01528c7244837168a1c80f06ff60fa5a9793c824

Rolling v8/tools/clang to 3e04436a49a26f4bd2c6f352efcf4c7b10a6d07d

TBR=machenbach@chromium.org,vogelheim@chromium.org,hablich@chromium.org

Review URL: https://codereview.chromium.org/1360563003

Cr-Commit-Position: refs/heads/master@{#30855}
2015-09-22 03:25:16 +00:00
dpranke
7d5d1570d9 Split the GN 'snapshot_toolchain' logic out into an include file.
We need to build parts of v8 with a toolchain that might be different
from both the default (target) toolchain and the regular host toolchain,
because we need the snapshot to have the same bit-width as the target.
V8's build defines a 'snapshot_toolchain' setting for this.

It turns out that we need the value of this toolchain to be exposed
to the Chromium build because some of the test targets (in browser_tests)
depend on d8 and need to be able to built using the same toolchain.

R=brett@chromium.org, jochen@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1350223004

Cr-Commit-Position: refs/heads/master@{#30854}
2015-09-22 02:28:40 +00:00
littledan
6e07f5a75b Stage sloppy block-scoped functions (Annex B 3.3)
Turn on some test262 tests that pass now.

R=adamk
LOG=Y
BUG=v8:4285

Review URL: https://codereview.chromium.org/1357233002

Cr-Commit-Position: refs/heads/master@{#30853}
2015-09-21 16:30:34 +00:00
bmeurer
e56f265f6d [ic] Also collect known map for relational comparison.
Previously we only collected the known map for equality comparisons. But
if we also collect it for relational comparisons, we can inline a fast
path of ToPrimitive on the objects, which is especially interesting
since both sides have the same map.

For now we only inline a very limited subset of ToPrimitive in
Crankshaft, which is when the receiver map (and its prototype chain)
doesn't have @@toPrimitive, and both valueOf and toString are the
default versions on the %ObjectPrototype%. In this case the relational
comparison would reduce to a string comparison of "[object CLASS]" with
itself and so we can reduce that to a boolean constant plus map checks
on both left and right hand side, plus code dependencies on the
prototype chain. This repairs the regression on box2d.

R=jkummerow@chromium.org
BUG=chromium:534200
LOG=n

Review URL: https://codereview.chromium.org/1355113002

Cr-Commit-Position: refs/heads/master@{#30852}
2015-09-21 16:05:43 +00:00
Michael Achenbach
c7a6790050 Whitespace change to test infra changes.
Cr-Commit-Position: refs/heads/master@{#30851}
2015-09-21 14:33:33 +00:00
mlippautz
41b8e10e1a [heap] Sort declarations for MemoryChunk.
R=hpayer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1360553003

Cr-Commit-Position: refs/heads/master@{#30850}
2015-09-21 14:03:56 +00:00
titzer
c610a22231 [turbofan] Add support for reinterpreting integers as floating point and vice versa.
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/1356913002

Cr-Commit-Position: refs/heads/master@{#30849}
2015-09-21 14:01:05 +00:00
hpayer
efc3fa02b0 [heap] Add timer scopes to process weak cells and clear non-live references.
BUG=

Review URL: https://codereview.chromium.org/1345273004

Cr-Commit-Position: refs/heads/master@{#30848}
2015-09-21 13:16:38 +00:00
bmeurer
704e3d809b [crankshaft] Generalize PropertyAccessInfo to Name (so it can deal with symbols).
This doesn't fix the performance regression mentioned by the bug yet,
but is necessary cleanup to land the fix, and should be separated from
the actual fix.

R=jkummerow@chromium.org
BUG=chromium:534200
LOG=n

Review URL: https://codereview.chromium.org/1345313005

Cr-Commit-Position: refs/heads/master@{#30847}
2015-09-21 12:58:16 +00:00
mythria
41111e3dc3 Continuing removing deprecated function from cctest
Removes deprecated functions from the following files:

test/cctest/compiler/function-tester.h
test/cctest/test-thread-termination.cc
test/cctest/test-threads.cc
test/cctest/test-transitions.cc
test/cctest/test-typedarrays.cc
test/cctest/test-types.cc
test/cctest/test-typing-reset.cc
test/cctest/test-unbound-queue.cc
test/cctest/test-unboxed-doubles.cc

BUG=v8:4134
LOG=n

Review URL: https://codereview.chromium.org/1344583002

Cr-Commit-Position: refs/heads/master@{#30846}
2015-09-21 10:34:59 +00:00
chunyang.dai
be04dd5c9e X87: [stubs] Refactor StringCompareStub and use it for HStringCompareAndBranch.
port 8016547c8e (r30818).

original commit message:

    The StringCompareStub used to take its parameters on the (JavaScript)
    stack, which made it impossible to use in TurboFan. Actually
    StringCompareStub was currently completely unused. This changes the
    calling convention to something TurboFan compatible and introduces a
    CallInterfaceDescriptor for StringCompareStub. It also changes
    HStringCompareAndBranch to use the StringCompareStub instead of using
    the full blown CompareICStub for a stupid string comparison.

BUG=

Review URL: https://codereview.chromium.org/1355983003

Cr-Commit-Position: refs/heads/master@{#30845}
2015-09-21 09:18:18 +00:00
chunyang.dai
9155967e84 X87: [runtime] Replace COMPARE/COMPARE_STRONG with proper Object::Compare.
port 593c655a3c (r30816).

original commit message:

    This removes the weird COMPARE and COMPARE_STRONG JavaScript builtins
    and replaces them with a proper C++ implementation in Object::Compare
    and appropriate wrappers Object::LessThan, Object::GreaterThan, and
    friends that are intended to be used by a true/false returning CompareIC
    in the future, as well as the interpreter.  As a short-term solution we
    provide %Compare and %Compare_Strong entry points for the current
    CompareIC that return the appropriate integer values expected by
    fullcodegen currently.

    Now the Abstract Relational Comparison is also using the correct
    ToPrimitive implementation, which properly supports @@toPrimitive.

BUG=

Review URL: https://codereview.chromium.org/1353343002

Cr-Commit-Position: refs/heads/master@{#30844}
2015-09-21 09:13:09 +00:00
julien.gilli
357e6b99ee Add ScopeInfo constants to post-mortem metadata
mdb_v8, a post-mortem debugging tool for Node.js, allows users to
inspect ScopeInfo structures in order to get more information about
closures.

Currently, it hardcodes the metadata it uses to find this information.
This change allows it to get this metadata from the node binary itself,
and thus to adapt to future changes made to the layout of the ScopeInfo
data structure.

BUG=

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/1350843003

Cr-Commit-Position: refs/heads/master@{#30843}
2015-09-21 05:45:38 +00:00
littledan
e5ff10d767 Implement sloppy-mode block-defined functions (Annex B 3.3)
ES2015 specifies very particular semantics for functions defined in blocks.
In strict mode, it is simply a lexical binding scoped to that block. In sloppy
mode, in addition to that lexical binding, there is a var-style binding in
the outer scope, which is overwritten with the local binding when the function
declaration is evaluated, *as long as* introducing ths var binding would not
create a var/let conflict in the outer scope.

This patch implements the semantics by introducing a DelegateStatement, which
is initially filled in with the EmptyStatement and overwritten with the
assignment when the scope is closed out and it can be checked that there is
no conflict.

This patch is tested with a new mjsunit test, and I tried staging it and running
test262, finding that the tests that we have disabled due to lack of Annex B
support now pass.

R=adamk,rossberg
LOG=Y
BUG=v8:4285

Review URL: https://codereview.chromium.org/1332873003

Cr-Commit-Position: refs/heads/master@{#30842}
2015-09-21 04:31:09 +00:00
alph
4962bbb135 Reland of Make profiler no frame region detection code more robust [ia86/x64]
Upon collection of the stack trace if the current PC falls into
the frame building code, the top frame might be in a non-consistent
state. That leads to some of the frames could be missing from the
stack trace.

The patch makes it check instructions under current PC and if they
look like the frame setup/destroy code, it skips the entire sample.

Support for x86/x64

CG_INCLUDE_TRYBOTS=tryserver.v8:v8_linux64_msan_rel
BUG=chromium:529931
LOG=N

Review URL: https://codereview.chromium.org/1348533005

Cr-Commit-Position: refs/heads/master@{#30841}
2015-09-20 16:40:28 +00:00
v8-autoroll
d44588a971 Update V8 DEPS.
Rolling v8/build/gyp to cf3170e30578d600b8ec8cd68553cc5e606d42eb

Rolling v8/tools/clang to 76e743dc622478312b66661ad48997b318628cbb

TBR=machenbach@chromium.org,vogelheim@chromium.org,hablich@chromium.org

Review URL: https://codereview.chromium.org/1357793002

Cr-Commit-Position: refs/heads/master@{#30840}
2015-09-19 03:26:10 +00:00
julien.gilli
ff7d70bf41 Update BitField3 type in gen-postmortem-metadata.py
Since https://codereview.chromium.org/272163002, BitField3 is a raw
uint32 field, and not a SMI anymore.

Update tools/gen-postmortem-metadata.py so that post-mortem tools can
work with versions of V8 that shipped after that change.

This change was merged in github.com/joyent/node right before node
v0.12.0 was released.

R=danno@chromium.org

TEST=mdb_v8, a post-mortem debugging tool running on SmartOS,  has been
using this change since Node.js v0.12.0 was released

BUG=

Review URL: https://codereview.chromium.org/1296743003

Cr-Commit-Position: refs/heads/master@{#30839}
2015-09-18 22:41:22 +00:00
mbrandy
5bbd5c58ef PPC: Fix AssertFunction.
R=joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1345223005

Cr-Commit-Position: refs/heads/master@{#30838}
2015-09-18 19:42:33 +00:00
mbrandy
d4d2ea7b8a PPC: [stubs] Refactor StringCompareStub and use it for HStringCompareAndBranch.
Port 8016547c8e

Original commit message:
    The StringCompareStub used to take its parameters on the (JavaScript)
    stack, which made it impossible to use in TurboFan. Actually
    StringCompareStub was currently completely unused. This changes the
    calling convention to something TurboFan compatible and introduces a
    CallInterfaceDescriptor for StringCompareStub. It also changes
    HStringCompareAndBranch to use the StringCompareStub instead of using
    the full blown CompareICStub for a stupid string comparison.

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1358553002

Cr-Commit-Position: refs/heads/master@{#30837}
2015-09-18 18:40:42 +00:00
mbrandy
8975286e9b PPC: [runtime] Replace COMPARE/COMPARE_STRONG with proper Object::Compare.
Port 593c655a3c

Original commit message:
    This removes the weird COMPARE and COMPARE_STRONG JavaScript builtins
    and replaces them with a proper C++ implementation in Object::Compare
    and appropriate wrappers Object::LessThan, Object::GreaterThan, and
    friends that are intended to be used by a true/false returning CompareIC
    in the future, as well as the interpreter.  As a short-term solution we
    provide %Compare and %Compare_Strong entry points for the current
    CompareIC that return the appropriate integer values expected by
    fullcodegen currently.

    Now the Abstract Relational Comparison is also using the correct
    ToPrimitive implementation, which properly supports @@toPrimitive.

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=v8:4307
LOG=n

Review URL: https://codereview.chromium.org/1356983002

Cr-Commit-Position: refs/heads/master@{#30836}
2015-09-18 18:39:19 +00:00
adamk
7462e99667 Remove on-by-default flag --harmony-object
It's been enabled since M45, which is now well into its stable period,
with no problems reported.

Review URL: https://codereview.chromium.org/1356793002

Cr-Commit-Position: refs/heads/master@{#30835}
2015-09-18 18:37:57 +00:00
adamk
bdf5b39f06 Stop emitting kSloppyLexical errors when --harmony-sloppy-let is enabled
This changes the error message for code like:

  if (false) let x;

from "Block-scoped declarations (let, const, function, class) not yet supported outside strict mode"
to "Unexpected identifier" (pointing at |x|).

Review URL: https://codereview.chromium.org/1356783002

Cr-Commit-Position: refs/heads/master@{#30834}
2015-09-18 18:20:07 +00:00
mtrofin
7864c35a76 [turbofan] Merge group spill ranges.
Akin to linear scan's TryReuseSpillForPhi, we attempt to merge the
spill ranges of grouped live ranges (which are phi inputs and output),
to avoid inefficient slot-to-slot moves.

BUG=

Review URL: https://codereview.chromium.org/1353023003

Cr-Commit-Position: refs/heads/master@{#30833}
2015-09-18 16:02:03 +00:00
bmeurer
90e1a0ddb3 [es6] Use the correct ToPrimitive in the Date Constructor.
This way we can finally remove the ES5 ToPrimitive builtin from
runtime.js, and the Date Constructor now properly supports
@@toPrimitive for the single argument case as well.

CQ_INCLUDE_TRYBOTS=tryserver.v8:v8_linux_layout_dbg,v8_linux_nosnap_dbg
R=rossberg@chromium.org
BUG=v8:4307
LOG=n

Review URL: https://codereview.chromium.org/1346893003

Cr-Commit-Position: refs/heads/master@{#30832}
2015-09-18 13:20:37 +00:00
mlippautz
4efa41f3bc [base] Fix check that makes sure we commit in the virtual memory range.
R=jochen@chromium.org
BUG=chromium:533342
LOG=N

Review URL: https://codereview.chromium.org/1349723005

Cr-Commit-Position: refs/heads/master@{#30831}
2015-09-18 12:41:34 +00:00
vogelheim
610c03007e Fix incorrect buffer length.
R=jochen@chromium.org
BUG=chromium:533243
LOG=N

Review URL: https://codereview.chromium.org/1356863002

Cr-Commit-Position: refs/heads/master@{#30830}
2015-09-18 12:07:24 +00:00
chunyang.dai
d10b2709df X87: Remove --pretenure-call-new
port b5588f48fd (r30767).

original commit message:

    There isn't a plan to turn it on soon, so we'll take it out in favor of cleaner code.

BUG=

Review URL: https://codereview.chromium.org/1346043005

Cr-Commit-Position: refs/heads/master@{#30829}
2015-09-18 12:01:04 +00:00
chunyang.dai
e8ec4ede62 X87: [runtime] Initial step towards switching Execution::Call to callable.
port d5bbd45f04 (r30808).

oringial commit message:

    Currently Execution::Call (and friends) still duplicate a lot of the
    Call sequence logic that should be encapsulated in the Call and
    CallFunction builtins. So the plan now is to switch Execution::Call
    to accept any Callable and just pass that through to the Call builtin.

BUG=

Review URL: https://codereview.chromium.org/1350183005

Cr-Commit-Position: refs/heads/master@{#30828}
2015-09-18 11:59:42 +00:00
chunyang.dai
953024c640 X87: Vector ICs: Hook up vectors in platform builtins to their SharedFunctionInfos.
port 905e008c52 (r30758)

BUG=

Review URL: https://codereview.chromium.org/1352173002

Cr-Commit-Position: refs/heads/master@{#30827}
2015-09-18 11:47:33 +00:00
chunyang.dai
55da29f443 X87: [builtins] Unify the String constructor.
port a3d6f6cce3 (r30759).

original commit message:

    Implement the String constructor completely as native builtin,
    avoiding the need to do gymnastics in JavaScript builtin to
    properly detect the no argument case (which is different from
    the undefined argument case) and also allowing to just
    tailcall through to ToString or SymbolDescriptiveString for
    the common case. Also the JavaScript builtin was misleading
    since the case for construct call was unused, but could be
    triggered in a wrong way once we support tail calls from
    constructor functions.

    This refactoring allows us to properly implement subclassing
    for String builtins, once we have the correct initial_map on
    derived classes (it's merely a matter of using NewTarget
    instead of the target register now).

    This introduces a new %SymbolDescriptiveString runtime
    entry, which is also used by Symbol.toString() now.

BUG=

Review URL: https://codereview.chromium.org/1349403002

Cr-Commit-Position: refs/heads/master@{#30826}
2015-09-18 11:46:34 +00:00
cbruni
061e2a9b2b elements.cc cleanup
Reuse code for copying arguments and pushing/shifting elements.

BUG=

Review URL: https://codereview.chromium.org/1346013005

Cr-Commit-Position: refs/heads/master@{#30825}
2015-09-18 11:15:49 +00:00
balazs.kilvady
b89eec39a1 MIPS64: Optimize simulator.
Port 09f41681ef

Original commit message:
The patch decreases the calls of huge switch instructions making the
DecodeType*() functions to work in one phase and optimizing
Instruction::InstructionType(). Speed gain in release full check is
about 33% (6:13 s -> 4:09 s) and in optdebug full test is about 50%
(12:29 -> 6:17)

BUG=

Review URL: https://codereview.chromium.org/1356693002

Cr-Commit-Position: refs/heads/master@{#30824}
2015-09-18 11:08:32 +00:00
cbruni
11c45e6d1e Fix --hydrogen-stats crashing on null_ptr for shared_info
BUG=

Review URL: https://codereview.chromium.org/1350293002

Cr-Commit-Position: refs/heads/master@{#30823}
2015-09-18 11:03:47 +00:00
mlippautz
8eec02b308 [heap] Cleanup: Align naming of parallel sweeping with parallel compaction.
Pure refactoring.

R=hpayer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1354613002

Cr-Commit-Position: refs/heads/master@{#30822}
2015-09-18 10:49:20 +00:00
bmeurer
eaef361791 [turbofan] Use StringCompareStub for string comparisons.
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1353103002

Cr-Commit-Position: refs/heads/master@{#30821}
2015-09-18 10:18:52 +00:00
brettw
cb2c22321f Use public_deps for v8_base in GN.
The previous code took advantage of the fact that a group's deps are implicitly public, but I'm trying to fix that. This also cleans up some duplicated code between component and non-component builds.

Review URL: https://codereview.chromium.org/1356723002

Cr-Commit-Position: refs/heads/master@{#30820}
2015-09-18 09:32:43 +00:00
jkummerow
491b9e29a0 [hydrogen] Add crash-hunting instrumentation to Hydrogen too
This extends instrumentation added in r30683 and r30768 to cover
the possibility that the root cause we're after is in optimized code.

This CL is intended to be reverted in a couple of days, but should
cause no harm while it's in the tree (we would crash anyway).

BUG=chromium:527994
LOG=n

Review URL: https://codereview.chromium.org/1348823003

Cr-Commit-Position: refs/heads/master@{#30819}
2015-09-18 09:15:46 +00:00