This increases the size of register operands to be 16-bit.
Not all bytecodes have wide register variants, so when they are
needed a register translator will copy them into a small area
reserved at the top of the 8-bit register range and these registers
are supplied as arguments to the bytecode with 8-bit operands.
This is non-intrusive for typical bytecode where the number of
registers is less than 120. For bytecodes with wide register
operands (above the window) their index needs to be translated
to avoid the reserved translation window.
Enables splay.js to run in Octane and a handful of mjsunit tests.
BUG=v8:4280,v8:4675
LOG=NO
Review URL: https://codereview.chromium.org/1613163002
Cr-Commit-Position: refs/heads/master@{#33516}
This adds an explicit ReThrow bytecode to be used in the modelling of
try-finally statements. An exception that is being re-thrown should not
trigger message object creation or location computation and hence cannot
use the existing Throw bytecode.
R=rmcilroy@chromium.org
TEST=cctest/test-interpreter/InterpreterTryFinally
BUG=v8:4674
LOG=n
Review URL: https://codereview.chromium.org/1621673002
Cr-Commit-Position: refs/heads/master@{#33472}
o Adds wide variants of bytecodes that have operands describing ranges
of registers. The upcoming wide register support does not suppport
re-mapping ranges.
o Adds kRegPair16 and kRegTriple16 operands required for new wide
bytecodes and renames Count8/Count16 operands to RegCount8/RegCount16.
o Removes Exchange bytecodes
BUG=v8:4675
LOG=NO
Review URL: https://codereview.chromium.org/1595103006
Cr-Commit-Position: refs/heads/master@{#33389}
Make ForInPrepare take a kRegTriple8 operand and ForInNext take kRegPair8
operand for cache state. This is to ensure that the cache state output of
ForInPrepare is in consecutive registers to allow us to deopt the
ForInPrepare node from TF->Ignition (to be done in a followup CL).
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1584813002
Cr-Commit-Position: refs/heads/master@{#33357}
Split RegisterAllocationScope out of ExpressionResult and allocate one
for each statement. This ensures that we always have an outer register
allocation scope for statement code (used in CountOperation and
RegisterExecutionResult). Also refactored the register allocator code to
move it to it's own file and rename from TemporaryRegisterScope to
BytecodeRegisterAllocator.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1587033002
Cr-Commit-Position: refs/heads/master@{#33296}
Adds support for calling runtime functions which return a pair of
values. Adds the bytecode CallRuntimePair. Also adds support to TurboFan
for calling stubs which return multiple values.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1568493002
Cr-Commit-Position: refs/heads/master@{#33181}
This increases the size of addressable constant pool entries for jumps
to match other bytecodes using operands indexing the constant pool.
This change also introduces reservations for constant pool entries.
Reservations are used for forward jumps to ensure a constant pool entry
will be available when the jump target (label) is bound and the jump is
patched up in the bytecode array.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1546683002
Cr-Commit-Position: refs/heads/master@{#33125}
New bytecodes for making registers with indicies wider than 1-byte
accessible.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1555713002
Cr-Commit-Position: refs/heads/master@{#33091}
Changes LoadGlobal, StoreGlobal, LoadNamedProperty, and StoreNamedProperty to accept
the name of variable instead of index into the constant pool entry. Also made
GetConstantPoolEntry as a private function since it is no longer used outside of
BytecodeArrayBuilder.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1546643002
Cr-Commit-Position: refs/heads/master@{#33020}
Adds support for deleting a variable in a lookup slot. Adds a new bytecode,
its implementation and tests. Also adds support for this bytecode to the
bytecode graph builder.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1542083002
Cr-Commit-Position: refs/heads/master@{#33019}
A pre-requisite for this change was changing the interpreter to use
Runtime::ForInStep to bring the interpreter implementation closer
to the turbofan implementation. Also required to flatten out the
cache parameters into the interpreter frame for de-opt.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1531693002
Cr-Commit-Position: refs/heads/master@{#32986}
Adds support for loading and storing lookup variables.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1524803003
Cr-Commit-Position: refs/heads/master@{#32913}
Adds implementation and tests for CreateObjectLiteral, CreateArrayLiteral and CreateRegExpLiteral
to bytecode graph builder. Also changes these bytecodes to expect three operands instead of using
accumulator to pass one of the operands. This is done to avoid looking into the earlier nodes to
fetch operands in the bytecode graph builder. Also adds support for wide variant of these
bytecodes to bytecode generator and bytecode graph builder.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1503963002
Cr-Commit-Position: refs/heads/master@{#32710}
ES6 section 12.2.8.1 states that flags for regular expression literals
must be checked during parsing and invalid flags are early errors. This
change adapts the Scanner and (Pre)Parser to act according to the spec.
This is also a prerequisite to unify the handling of literal creation
(for Objects, Arrays, Regexps, and at some point Classes).
R=yangguo@chromium.org
Review URL: https://codereview.chromium.org/1472323002
Cr-Commit-Position: refs/heads/master@{#32273}
Adds code and tests to support CreateClosure bytecode when building
graphs.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1458603012
Cr-Commit-Position: refs/heads/master@{#32224}
This change introduces register re-mapping to avoid assignment hazards
in binary expressions. Expressions that cause problems typically have
the form y = x + (x = 4);. The problem occurs because the lhs value
evaluates to the register holding x. The rhs updates that register and
then applying the operation would use the new value as the lhs.
By tracking loads and stores in binary expressions the generator is now
able to detect when condition occurs and uses a temporary register for
the rhs value. When the binary expression evaluation is complete the
variable is updated with the latest temporary.
A new bytecode Mov performs this update without touching the
accumulator.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1412683011
Cr-Commit-Position: refs/heads/master@{#32141}
Adds support for visiting the Call bytecode to the bytecode graph builder.
This change also adds the call type feedback slot to the Call bytecode.
This is not currently used by the interpreter, but is used by the
graph builder.
Also adds a CallWide varient of the Call bytecode, and adds the kCount16
operand type.
Landed on behalf of rmcilroy.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1456453002
Cr-Commit-Position: refs/heads/master@{#32033}
Adds an optimization to omit generating Ldar/Star if the same register
is loaded or stored from the accumulator in the earlier instruction.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1435283002
Cr-Commit-Position: refs/heads/master@{#31984}
Adds support for calling JS runtime functions. Also changes the bytecode
array builder to allow calling functions with an invalid argument
register if the call takes no arguments.
Adds the bytecode CallJSRuntime.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1410003003
Cr-Commit-Position: refs/heads/master@{#31774}
Corrects LdaGlobal to deal with TypeofMode::INSIDE_TYPEOF so that it
doesn't throw a reference error on undefined globals.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1422443006
Cr-Commit-Position: refs/heads/master@{#31757}
Existing code was assuming that 'lexical' blocks were the same as basic
blocks, therefore code which emitted jumps within a lexical block (e.g.,
logical or) would in some occassions incorrectly omit a necessary
ToBoolean.
This change removes Enter/LeaveBlock from BytecodeArrayBuilder and
instead tracks basic blocks via label bindings and jump operations. The
change also ensures we don't emit dead code at the end of a basic block,
and adds tests of the edge cases.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1406983010
Cr-Commit-Position: refs/heads/master@{#31741}
Adds an optimization to emit JumpIfToBooleanTrue/False instead
of ToBoolean followed by JumpIfTrue/False if the value in the
accumulator is not boolean.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1426913002
Cr-Commit-Position: refs/heads/master@{#31697}
For..in introduces 3 new bytecodes ForInPrepare, ForInNext, and
ForInDone to start a for..in loop, get the next element, and check if
the loop is done.
For..in builds upon new LoopBuilder constructs for conditionally
breaking and continuing during iteration: BreakIf{Null|Undefined}
and ContinueIf{Null|Undefined}. New conditional jump bytecodes
support this succinctly: JumpIfNull and JumpIfUndefined.
Add missing check to BytecodeLabel that could allow multiple
forward referencess to the same label which is not supported.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1422033002
Cr-Commit-Position: refs/heads/master@{#31651}
Adds support for delete operator, it's implementation and tests.
Adds tests for the following unary operators
-BitwiseNot
-Add
-Sub
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1410953003
Cr-Commit-Position: refs/heads/master@{#31620}
Fills out some more of the function prologue support in the
interpreter. Deals with creation of arguments objects and throwing
IllegalRedeclarations if necessary. Also adds (untested) support for
this.function and new.target variable assignment.
Also fixes a bug in Frames::is_java_script() to deal with
interpreter frames correctly.
Cleans up comments in builtins InterpreterEntryTrampoline about
missing prologue support.
Adds the following bytecodes:
- CreateArgumentsSloppy
- CreateArgumentsStrict
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1412953007
Cr-Commit-Position: refs/heads/master@{#31486}
Adds support for count operations to the interpreter. Deals with count
operations on locals, globals, context allocated variables and named and
keyed properties.
Adds the following bytecodes:
ToNumber
Inc
Dec
BUG=v8:4280
LOG=N
TBR=mstarzinger@chromium.org
Review URL: https://codereview.chromium.org/1416623003
Cr-Commit-Position: refs/heads/master@{#31484}
Unifies the global and unallocated variable type accesses given that
--global_var_shortcuts is going away. Lda/StaGlobal is modified to use
Load/StoreICs on the global object. The named LoadIC and StoreIC bytecodes
are also modified so that they take a constant pool entry index for the
name rather than a register, avoiding unecessary LdaConstant bytecodes to
be emitted.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1419003002
Cr-Commit-Position: refs/heads/master@{#31482}
The plan is to implement the same idea using vector IC machinery.
Stubs implementations and scopes modifications are left untouched for now.
Review URL: https://codereview.chromium.org/1419823003
Cr-Commit-Position: refs/heads/master@{#31458}
This change adds new flavors of Visit() methods for obtaining
expression results:
- VisitForAccumulatorValue() which places result in the accumulator.
- VisitForRegisterValue() which places the result in a register.
- VisitForEffect() which evaluates the expression and discards the result.
The targets of these calls place the expression result with
result_scope()->SetResultInRegister() or
result_scope()->SetResultInAccumulator().
By being smarter about result locations, there's less temporary
register usage. However, we now have a hazard with assignments
in binary expressions that didn't exist before. This change detects and
DCHECK's when a hazard is detected. A follow on CL will address this.
There are consequential changes to test-bytecode-generator.cc and
this change also adds new bytecode macros A(x, n) and THIS(n) for
register file entries for arguments and this.
BUG=v8:4280
LOG=NO
Review URL: https://codereview.chromium.org/1392933002
Cr-Commit-Position: refs/heads/master@{#31445}
Adds support for local context loads and stores. Also adds support for
creation of new block contexts (e.g., for let variables) and initializing
const / let variables with the hole appropriately.
Also adds some checks to ensure BytecodeArrayBuilder::context_count is set
appropriately and fixes tests to do so.
Adds the bytecode StaContextSlot.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1403943004
Cr-Commit-Position: refs/heads/master@{#31343}
This change add a new bytecode for operator new and implements it using
the Construct() builtin.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1402943002
Cr-Commit-Position: refs/heads/master@{#31293}
Adds support for following operators
-Logical and
-Logical or
-Comma
Adds the above bytecodes, support to BytecodeGenerator and BytecodeArrayBuilder
to enable it's use, it's implementation and tests.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1399773002
Cr-Commit-Position: refs/heads/master@{#31281}
Replaces the use of KeyedStoreICGeneric with a vector based KeyedStoreIC for
array literal computed stores now that there is a feedback vector slot for
these expressions. Removes KeyedStoreICGeneric bytecode since this is no
longer necessary.
BUG=v8:4280
LOG=N
TBR=mstarzinger@chromium.org
Review URL: https://codereview.chromium.org/1400353002
Cr-Commit-Position: refs/heads/master@{#31262}
Adds Object literal support to the interpreter. Adds the following bytecodes:
- ToName
- CreateObjectLiteral.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1386313005
Cr-Commit-Position: refs/heads/master@{#31253}
Adds array literal support to the interpreter. Currently constructed
array elements don't have type feedback slots, so also adds support for
generic keyed store operations.
Adds the following bytecodes:
- CreateArrayLiteral
- KeyedStoreICGeneric
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1400753003
Cr-Commit-Position: refs/heads/master@{#31240}
Adds support for creation of new local function contexts (or script context for
top-level code). As part of this, also adds support for context push/pop
operations using a ContextScope object in BytecodeGenerator. Adds the following
bytecodes:
- PushContext
- PopContext
Support for inner contexts and loading from / storing to context allocated
variables will come in a future CL.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1379793004
Cr-Commit-Position: refs/heads/master@{#31238}
Adds function literal support and add support for OTHER_CALLS which can be
made when calling a function literal.
Adds the CreateClosure bytecode.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1396693003
Cr-Commit-Position: refs/heads/master@{#31231}
-Bitwise Or
-Bitwise Xor
-Bitwise And
Adds the above bytecodes, support to BytecodeGenerator and BytecodeArrayBuilder to enable it's use, it's implementation and tests.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1386133002
Cr-Commit-Position: refs/heads/master@{#31210}
Adds support for following operators
-Shift left
-Shift right
-Shift right logical
Adds the above bytecodes, support to BytecodeGenerator and BytecodeArrayBuilder
to enable it's use, it's implementation and tests.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1392913002
Cr-Commit-Position: refs/heads/master@{#31205}
Implements support for declaring global variables. Also adds support for loading
from and storing to both global and unallocated global variables. Adds the
following bytecodes:
- StoreGlobal
- LoadContextSlot
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1378523005
Cr-Commit-Position: refs/heads/master@{#31166}
Adds support for strict mode load / store ICs and cleans up BinaryOp and
CompareOp to only trigger an UNIMPLEMENTED abort if called with STRONG
mode (which is the only language mode which has different compare/binary ops.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1385623002
Cr-Commit-Position: refs/heads/master@{#31134}
Implementations and tests for typeof, void, and logical not.
Add missing string type to Object::TypeOf.
BUG=v8:4280
LOG=NO
Review URL: https://codereview.chromium.org/1390483002
Cr-Commit-Position: refs/heads/master@{#31124}
Adds support for calling runtime functions from the interpreter. Adds the
CallRuntime bytecode which takes a Runtime::FunctionId of the function to call
and the arguments in sequential registers. Adds a InterpreterCEntry builtin
to enable the interpreter to enter C++ code based on the functionId.
Also renames Builtin::PushArgsAndCall to Builtin::InterpreterPushArgsAndCall
and groups all the interpreter builtins together.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1362383002
Cr-Commit-Position: refs/heads/master@{#31089}
Reason for revert:
Now breaking arm32 debug bot (worked locally even with --debug-code, so I'll need to figure out what's different on the bot)
Original issue's description:
> [Interpreter] Add CallRuntime support to the interpreter.
>
> Adds support for calling runtime functions from the interpreter. Adds the
> CallRuntime bytecode which takes a Runtime::FunctionId of the function to call
> and the arguments in sequential registers. Adds a InterpreterCEntry builtin
> to enable the interpreter to enter C++ code based on the functionId.
>
> Also renames Builtin::PushArgsAndCall to Builtin::InterpreterPushArgsAndCall
> and groups all the interpreter builtins together.
>
> BUG=v8:4280
> LOG=N
>
TBR=bmeurer@chromium.org,oth@chromium.org,mstarzinger@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4280
Review URL: https://codereview.chromium.org/1379933003
Cr-Commit-Position: refs/heads/master@{#31078}
Adds support for calling runtime functions from the interpreter. Adds the
CallRuntime bytecode which takes a Runtime::FunctionId of the function to call
and the arguments in sequential registers. Adds a InterpreterCEntry builtin
to enable the interpreter to enter C++ code based on the functionId.
Also renames Builtin::PushArgsAndCall to Builtin::InterpreterPushArgsAndCall
and groups all the interpreter builtins together.
BUG=v8:4280
LOG=N
Committed: https://crrev.com/40e8424b744f8b6e3e1d93e20f23487419911dfc
Cr-Commit-Position: refs/heads/master@{#31064}
Review URL: https://codereview.chromium.org/1362383002
Cr-Commit-Position: refs/heads/master@{#31076}
Reason for revert:
Broke Arm64 bot (CEntry stub is trying to pop arguments off stack when argv_in_reg, so I need to fix this).
Original issue's description:
> [Interpreter] Add CallRuntime support to the interpreter.
>
> Adds support for calling runtime functions from the interpreter. Adds the
> CallRuntime bytecode which takes a Runtime::FunctionId of the function to call
> and the arguments in sequential registers. Adds a InterpreterCEntry builtin
> to enable the interpreter to enter C++ code based on the functionId.
>
> Also renames Builtin::PushArgsAndCall to Builtin::InterpreterPushArgsAndCall
> and groups all the interpreter builtins together.
>
> BUG=v8:4280
> LOG=N
>
> Committed: https://crrev.com/40e8424b744f8b6e3e1d93e20f23487419911dfc
> Cr-Commit-Position: refs/heads/master@{#31064}
TBR=bmeurer@chromium.org,oth@chromium.org,mstarzinger@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4280
Review URL: https://codereview.chromium.org/1387543002
Cr-Commit-Position: refs/heads/master@{#31066}
Adds support for calling runtime functions from the interpreter. Adds the
CallRuntime bytecode which takes a Runtime::FunctionId of the function to call
and the arguments in sequential registers. Adds a InterpreterCEntry builtin
to enable the interpreter to enter C++ code based on the functionId.
Also renames Builtin::PushArgsAndCall to Builtin::InterpreterPushArgsAndCall
and groups all the interpreter builtins together.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1362383002
Cr-Commit-Position: refs/heads/master@{#31064}
Adds support for short operands, starting with kIdx16. Introduces
BytecodeTraits to enable compile time determination of various traits for a
bytecode, such as size, operands, etc. Reworks BytecodeIterator,
BytecodeArrayBuilder and Bytecodes::Decode to support 16 bit operands. Adds
support to Interpreter to load 16 bit operands.
Also fixes a bug with ToBoolean where it wouldn't get emitted at the start
of a block, and added a test.
BytecodeTraits template magic inspired by oth@chromium.org.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1370893002
Cr-Commit-Position: refs/heads/master@{#31058}
+ Add bytecodes for conditional and unconditional jumps.
+ Add bytecodes for test/compare operations.
+ Expose jumps in bytecode-array-builder and add BytecodeLabel class for
identifying jump targets.
+ Add support for if..then...else in the bytecode-generator.
+ Implement jump bytecodes in the interpreter. Test/compare operations
dependent on runtime call for comparisons.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1343363002
Cr-Commit-Position: refs/heads/master@{#30918}
Adds LdaGlobal bytecode and augments BytecodeGenerator to load globals for
global variables and function calls.
Modified TestBytecodeGenerator to add the ability to specify that a bytecode
operand has an unknown value (used so we don't need to figure out the slot
index of a global). Also added a helper which checks equality of BytecodeArray
with the expected snipptets.
Modified TestInterpreter to allow it to take snippets of JS and have the
BytecodeGenerator generate the bytecode rather than having to build a
BytecodeArray manually. This is used to enable the global tests.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1361113002
Cr-Commit-Position: refs/heads/master@{#30910}
Adds support for JS calls to the interpreter. In order to support
calls from the interpreter, the PushArgsAndCall builtin is added
which pushes a sequence of arguments onto the stack and calls
builtin::Call.
Adds the Call bytecode.
MIPS port contributed by akos.palfi@imgtec.com in https://codereview.chromium.org/1334873002/
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1323463005
Cr-Commit-Position: refs/heads/master@{#30710}
Adds support for property store operations via Store/KeyedStore ICs. Adds the
following bytecodes:
- StoreIC
- KeyedStoreIC
The --vector_store flag is now required for --ignition.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1319833004
Cr-Commit-Position: refs/heads/master@{#30660}
Adds support for property load operations via Load/KeyedLoad ICs. Adds the
following bytecodes:
- LoadIC
- KeyedLoadIC
Also adds support to the interpreter assembler for loading the type feedback
vector from the function on the stack, and calling ICs.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1309843007
Cr-Commit-Position: refs/heads/master@{#30543}
Adds support to the interpreter for loading literals from the constant pool.
Adds the LoadConstant bytecode and makes use of it for loading large Smis and
HeapObject literals.
Also removes unused HandleVector from utils.h.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1321663003
Cr-Commit-Position: refs/heads/master@{#30450}
Adds support for parameters to the BytecodeArrayBuilder and BytecodeGenerator.
Parameters are accessed as negative interpreter registers.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1303403004
Cr-Commit-Position: refs/heads/master@{#30403}
Adds implementations and tests for the following bytecodes:
- Add
- Sub
- Mul
- Div
- Mod
Also adds the Mod bytecode and adds support to BytecodeGenerator and
BytecodeArrayBuilder to enable it's use.
The current bytecodes always call through to the JS builtins. This also adds
LoadObjectField and CallJSBuiltin operators to the InterpreterAssembler.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1300813005
Cr-Commit-Position: refs/heads/master@{#30352}
Modifies the BytecodeArrayBuilder to create register operands which are
negative. This reduces the number of instructions to access registers
by the interpreter and allows us to use positive register operands to
access parameter values.
Adds a Register class to keep register usage typesafe and simplify the
convertion to bytecode operand values.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1283313003
Cr-Commit-Position: refs/heads/master@{#30151}
