Collect type information for JavaScript variables and display it
in Chrome DevTools.
Design Doc: https://docs.google.com/a/google.com/document/d/1O1uepXZXBI6IwiawTrYC3ohhiNgzkyTdjn3R8ysbYgk/edit?usp=sharing
When debugging JavaScript, it’s helpful to know the type of
a variable, parameter, and return values. JavaScript is
dynamically typed, and for complex
source code it’s often hard to infer types. With type profiling, we
can provide type information to JavaScript developers.
This CL is a proof of concept. It collects type profile for
assignments and simply prints the types to stdout.
The output looks something like this:
#my_var1
#Object
#number
#string
#number
#undefined
#string
#Object
#Object
We use an extra slot in the feedback vector of assignments to
carry the list of types for that assignment. The extra slot is
only added when the flag --type-profile is given.
Missing work:
* Collect data for parameters and return values (currently only assignments).
* Remove duplicates from the list of collected types and use a common base class.
* Add line numbers or source position instead of the variable name.
For now, has a test that compares the stdout of --type-profile in test/message. We
will remove this test when --type-profile is fully integrated in
the debugger protocol. Adding
the test in test/inspector does not work, because the inspector
test itself consists of JavaScript code that would convolute the
output and be non-deterministic under stress.
BUG=v8:5935
Review-Url: https://codereview.chromium.org/2707873002
Cr-Commit-Position: refs/heads/master@{#43866}
Reason for revert:
Still flaky
Original issue's description:
> Collect type profile for DevTools
>
> Collect type information for JavaScript variables and display it
> in Chrome DevTools.
> Design Doc: https://docs.google.com/a/google.com/document/d/1O1uepXZXBI6IwiawTrYC3ohhiNgzkyTdjn3R8ysbYgk/edit?usp=sharing
>
> When debugging JavaScript, it’s helpful to know the type of
> a variable, parameter, and return values. JavaScript is
> dynamically typed, and for complex
> source code it’s often hard to infer types. With type profiling, we
> can provide type information to JavaScript developers.
>
> This CL is a proof of concept. It collects type profile for
> assignments and simply prints the types to stdout.
>
> The output looks something like this:
>
> #my_var1
> #Object
> #number
> #string
> #number
> #undefined
> #string
> #Object
> #Object
>
>
> We use an extra slot in the feedback vector of assignments to
> carry the list of types for that assignment. The extra slot is
> only added when the flag --type-profile is given.
>
>
> Missing work:
> * Collect data for parameters and return values (currently only assignments).
> * Remove duplicates from the list of collected types and use a common base class.
> * Add line numbers or source position instead of the variable name.
>
>
>
> BUG=v8:5935
>
> Review-Url: https://codereview.chromium.org/2707873002
> Cr-Original-Original-Original-Commit-Position: refs/heads/master@{#43791}
> Committed: 0332bebde9
> Review-Url: https://codereview.chromium.org/2707873002
> Cr-Original-Original-Commit-Position: refs/heads/master@{#43804}
> Committed: 6cf880f4b8
> Review-Url: https://codereview.chromium.org/2707873002
> Cr-Original-Commit-Position: refs/heads/master@{#43846}
> Committed: 5c32287390
> Review-Url: https://codereview.chromium.org/2707873002
> Cr-Commit-Position: refs/heads/master@{#43849}
> Committed: 18c35e4958TBR=yangguo@chromium.org,mvstanton@chromium.org,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=v8:5935
Review-Url: https://codereview.chromium.org/2745413006
Cr-Commit-Position: refs/heads/master@{#43852}
Collect type information for JavaScript variables and display it
in Chrome DevTools.
Design Doc: https://docs.google.com/a/google.com/document/d/1O1uepXZXBI6IwiawTrYC3ohhiNgzkyTdjn3R8ysbYgk/edit?usp=sharing
When debugging JavaScript, it’s helpful to know the type of
a variable, parameter, and return values. JavaScript is
dynamically typed, and for complex
source code it’s often hard to infer types. With type profiling, we
can provide type information to JavaScript developers.
This CL is a proof of concept. It collects type profile for
assignments and simply prints the types to stdout.
The output looks something like this:
#my_var1
#Object
#number
#string
#number
#undefined
#string
#Object
#Object
We use an extra slot in the feedback vector of assignments to
carry the list of types for that assignment. The extra slot is
only added when the flag --type-profile is given.
Missing work:
* Collect data for parameters and return values (currently only assignments).
* Remove duplicates from the list of collected types and use a common base class.
* Add line numbers or source position instead of the variable name.
BUG=v8:5935
Review-Url: https://codereview.chromium.org/2707873002
Cr-Original-Original-Original-Commit-Position: refs/heads/master@{#43791}
Committed: 0332bebde9
Review-Url: https://codereview.chromium.org/2707873002
Cr-Original-Original-Commit-Position: refs/heads/master@{#43804}
Committed: 6cf880f4b8
Review-Url: https://codereview.chromium.org/2707873002
Cr-Original-Commit-Position: refs/heads/master@{#43846}
Committed: 5c32287390
Review-Url: https://codereview.chromium.org/2707873002
Cr-Commit-Position: refs/heads/master@{#43849}
Reason for revert:
Flaky under stress. Fix first.
Original issue's description:
> Collect type profile for DevTools
>
> Collect type information for JavaScript variables and display it
> in Chrome DevTools.
> Design Doc: https://docs.google.com/a/google.com/document/d/1O1uepXZXBI6IwiawTrYC3ohhiNgzkyTdjn3R8ysbYgk/edit?usp=sharing
>
> When debugging JavaScript, it’s helpful to know the type of
> a variable, parameter, and return values. JavaScript is
> dynamically typed, and for complex
> source code it’s often hard to infer types. With type profiling, we
> can provide type information to JavaScript developers.
>
> This CL is a proof of concept. It collects type profile for
> assignments and simply prints the types to stdout.
>
> The output looks something like this:
>
> #my_var1
> #Object
> #number
> #string
> #number
> #undefined
> #string
> #Object
> #Object
>
>
> We use an extra slot in the feedback vector of assignments to
> carry the list of types for that assignment. The extra slot is
> only added when the flag --type-profile is given.
>
>
> Missing work:
> * Collect data for parameters and return values (currently only assignments).
> * Remove duplicates from the list of collected types and use a common base class.
> * Add line numbers or source position instead of the variable name.
>
>
>
> BUG=v8:5935
>
> Review-Url: https://codereview.chromium.org/2707873002
> Cr-Original-Original-Commit-Position: refs/heads/master@{#43791}
> Committed: 0332bebde9
> Review-Url: https://codereview.chromium.org/2707873002
> Cr-Original-Commit-Position: refs/heads/master@{#43804}
> Committed: 6cf880f4b8
> Review-Url: https://codereview.chromium.org/2707873002
> Cr-Commit-Position: refs/heads/master@{#43846}
> Committed: 5c32287390TBR=yangguo@chromium.org,mvstanton@chromium.org,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=v8:5935
Review-Url: https://codereview.chromium.org/2747383004
Cr-Commit-Position: refs/heads/master@{#43847}
Collect type information for JavaScript variables and display it
in Chrome DevTools.
Design Doc: https://docs.google.com/a/google.com/document/d/1O1uepXZXBI6IwiawTrYC3ohhiNgzkyTdjn3R8ysbYgk/edit?usp=sharing
When debugging JavaScript, it’s helpful to know the type of
a variable, parameter, and return values. JavaScript is
dynamically typed, and for complex
source code it’s often hard to infer types. With type profiling, we
can provide type information to JavaScript developers.
This CL is a proof of concept. It collects type profile for
assignments and simply prints the types to stdout.
The output looks something like this:
#my_var1
#Object
#number
#string
#number
#undefined
#string
#Object
#Object
We use an extra slot in the feedback vector of assignments to
carry the list of types for that assignment. The extra slot is
only added when the flag --type-profile is given.
Missing work:
* Collect data for parameters and return values (currently only assignments).
* Remove duplicates from the list of collected types and use a common base class.
* Add line numbers or source position instead of the variable name.
BUG=v8:5935
Review-Url: https://codereview.chromium.org/2707873002
Cr-Original-Original-Commit-Position: refs/heads/master@{#43791}
Committed: 0332bebde9
Review-Url: https://codereview.chromium.org/2707873002
Cr-Original-Commit-Position: refs/heads/master@{#43804}
Committed: 6cf880f4b8
Review-Url: https://codereview.chromium.org/2707873002
Cr-Commit-Position: refs/heads/master@{#43846}
Adds a TestTypeof bytecode to deal with comparisons of the form:
typeof(object) === 'string';
Also adds support to Turbofan to perform these comparisons without
inserting checkpoints.
BUG=v8:4280,v8:5267
Change-Id: Ib5cc1c6816dfe70a4120838d8eada2fc0267750f
Reviewed-on: https://chromium-review.googlesource.com/454837
Reviewed-by: Mythri Alle <mythria@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43832}
Reason for revert:
gcc bot is now flaky https://build.chromium.org/p/client.v8/builders/V8%20Linux%20gcc%204.8/builds/11863
Original issue's description:
> Collect type profile for DevTools
>
> Collect type information for JavaScript variables and display it
> in Chrome DevTools.
> Design Doc: https://docs.google.com/a/google.com/document/d/1O1uepXZXBI6IwiawTrYC3ohhiNgzkyTdjn3R8ysbYgk/edit?usp=sharing
>
> When debugging JavaScript, it’s helpful to know the type of
> a variable, parameter, and return values. JavaScript is
> dynamically typed, and for complex
> source code it’s often hard to infer types. With type profiling, we
> can provide type information to JavaScript developers.
>
> This CL is a proof of concept. It collects type profile for
> assignments and simply prints the types to stdout.
>
> The output looks something like this:
>
> #my_var1
> #Object
> #number
> #string
> #number
> #undefined
> #string
> #Object
> #Object
>
>
> We use an extra slot in the feedback vector of assignments to
> carry the list of types for that assignment. The extra slot is
> only added when the flag --type-profile is given.
>
>
> Missing work:
> * Collect data for parameters and return values (currently only assignments).
> * Remove duplicates from the list of collected types and use a common base class.
> * Add line numbers or source position instead of the variable name.
>
>
>
> BUG=v8:5935
>
> Review-Url: https://codereview.chromium.org/2707873002
> Cr-Original-Commit-Position: refs/heads/master@{#43791}
> Committed: 0332bebde9
> Review-Url: https://codereview.chromium.org/2707873002
> Cr-Commit-Position: refs/heads/master@{#43804}
> Committed: 6cf880f4b8TBR=yangguo@chromium.org,mvstanton@chromium.org,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=v8:5935
Review-Url: https://codereview.chromium.org/2754573002
Cr-Commit-Position: refs/heads/master@{#43805}
Collect type information for JavaScript variables and display it
in Chrome DevTools.
Design Doc: https://docs.google.com/a/google.com/document/d/1O1uepXZXBI6IwiawTrYC3ohhiNgzkyTdjn3R8ysbYgk/edit?usp=sharing
When debugging JavaScript, it’s helpful to know the type of
a variable, parameter, and return values. JavaScript is
dynamically typed, and for complex
source code it’s often hard to infer types. With type profiling, we
can provide type information to JavaScript developers.
This CL is a proof of concept. It collects type profile for
assignments and simply prints the types to stdout.
The output looks something like this:
#my_var1
#Object
#number
#string
#number
#undefined
#string
#Object
#Object
We use an extra slot in the feedback vector of assignments to
carry the list of types for that assignment. The extra slot is
only added when the flag --type-profile is given.
Missing work:
* Collect data for parameters and return values (currently only assignments).
* Remove duplicates from the list of collected types and use a common base class.
* Add line numbers or source position instead of the variable name.
BUG=v8:5935
Review-Url: https://codereview.chromium.org/2707873002
Cr-Original-Commit-Position: refs/heads/master@{#43791}
Committed: 0332bebde9
Review-Url: https://codereview.chromium.org/2707873002
Cr-Commit-Position: refs/heads/master@{#43804}
Reason for revert:
gcc bot has problems with this: https://build.chromium.org/p/client.v8/builders/V8%20Linux%20gcc%204.8/builds/11858
Original issue's description:
> Collect type profile for DevTools
>
> Collect type information for JavaScript variables and display it
> in Chrome DevTools.
> Design Doc: https://docs.google.com/a/google.com/document/d/1O1uepXZXBI6IwiawTrYC3ohhiNgzkyTdjn3R8ysbYgk/edit?usp=sharing
>
> When debugging JavaScript, it’s helpful to know the type of
> a variable, parameter, and return values. JavaScript is
> dynamically typed, and for complex
> source code it’s often hard to infer types. With type profiling, we
> can provide type information to JavaScript developers.
>
> This CL is a proof of concept. It collects type profile for
> assignments and simply prints the types to stdout.
>
> The output looks something like this:
>
> #my_var1
> #Object
> #number
> #string
> #number
> #undefined
> #string
> #Object
> #Object
>
>
> We use an extra slot in the feedback vector of assignments to
> carry the list of types for that assignment. The extra slot is
> only added when the flag --type-profile is given.
>
>
> Missing work:
> * Collect data for parameters and return values (currently only assignments).
> * Remove duplicates from the list of collected types and use a common base class.
> * Add line numbers or source position instead of the variable name.
>
>
>
> BUG=v8:5935
>
> Review-Url: https://codereview.chromium.org/2707873002
> Cr-Commit-Position: refs/heads/master@{#43791}
> Committed: 0332bebde9TBR=yangguo@chromium.org,mvstanton@chromium.org,rmcilroy@chromium.org,mstarzinger@chromium.org,franzih@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:5935
Review-Url: https://codereview.chromium.org/2749673003
Cr-Commit-Position: refs/heads/master@{#43798}
Collect type information for JavaScript variables and display it
in Chrome DevTools.
Design Doc: https://docs.google.com/a/google.com/document/d/1O1uepXZXBI6IwiawTrYC3ohhiNgzkyTdjn3R8ysbYgk/edit?usp=sharing
When debugging JavaScript, it’s helpful to know the type of
a variable, parameter, and return values. JavaScript is
dynamically typed, and for complex
source code it’s often hard to infer types. With type profiling, we
can provide type information to JavaScript developers.
This CL is a proof of concept. It collects type profile for
assignments and simply prints the types to stdout.
The output looks something like this:
#my_var1
#Object
#number
#string
#number
#undefined
#string
#Object
#Object
We use an extra slot in the feedback vector of assignments to
carry the list of types for that assignment. The extra slot is
only added when the flag --type-profile is given.
Missing work:
* Collect data for parameters and return values (currently only assignments).
* Remove duplicates from the list of collected types and use a common base class.
* Add line numbers or source position instead of the variable name.
BUG=v8:5935
Review-Url: https://codereview.chromium.org/2707873002
Cr-Commit-Position: refs/heads/master@{#43791}
... which is used for initializing properties with non compile time values.
Currently we use StoreOwnIC only for storing properties that already exist
in the boilerplate therefore we can reuse StoreIC dispatcher.
The proper StoreOwnIC dispatcher will be implemented in a separate CL.
BUG=v8:5495, v8:4414
Change-Id: I9c33fdb8499ec5be2c7fce1ecb6ce7aa285e5844
Reviewed-on: https://chromium-review.googlesource.com/443588
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43285}
When --harmony-async-iteration is enabled, it is now possible to
use the for-await-of loop, which uses the Async Iteration protocol
rather than the ordinary ES6 Iteration protocol.
the Async-from-Sync Iterator object is not implemented in this CL,
and so for-await-of loops will abort execution if the iterated object
does not have a Symbol.asyncIterator() method. Async-from-Sync
Iterators are implemented seperately in https://codereview.chromium.org/2645313003/
BUG=v8:5855, v8:4483
R=neis@chromium.org, littledan@chromium.org, adamk@chromium.org
Review-Url: https://codereview.chromium.org/2637403008
Cr-Commit-Position: refs/heads/master@{#43224}
Removes handles from bytecode generation, instead storing
un-internalized AstValues (and other, similar values such as Scopes and
AstRawStrings) in the constant array builder.
This will allow us in the future to generate the bytecode before
internalizing the AST.
BUG=v8:5832
Change-Id: I3b8be8f7329a484eb1e5d12808b001d3475239da
Reviewed-on: https://chromium-review.googlesource.com/439326
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43115}
Reason for revert:
False alarm, bot hiccup
Original issue's description:
> Revert of Thread maybe-assigned through the bytecodes. (patchset #5 id:80001 of https://codereview.chromium.org/2655733003/ )
>
> Reason for revert:
> needed for properly reverting f3ae5ccf57
>
> Original issue's description:
> > Thread maybe-assigned through the bytecodes.
> >
> > This introduces LoadImmutableContextSlot and LoadImmutableCurrentContextSlot
> > bytecodes, which are emitted when reading from never-assigned context slot.
> >
> > There is a subtlety here: the slot are not immutable, the meaning is
> > actually undefined-or-hole-or-immutable.
> >
> > Review-Url: https://codereview.chromium.org/2655733003
> > Cr-Commit-Position: refs/heads/master@{#43000}
> > Committed: 17c2dd3886
>
> TBR=rmcilroy@chromium.org,bmeurer@chromium.org,neis@chromium.org,jarin@chromium.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
>
> Review-Url: https://codereview.chromium.org/2680923003
> Cr-Commit-Position: refs/heads/master@{#43011}
> Committed: ece4e54a31TBR=rmcilroy@chromium.org,bmeurer@chromium.org,neis@chromium.org,jarin@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Review-Url: https://codereview.chromium.org/2679953003
Cr-Commit-Position: refs/heads/master@{#43012}
Reason for revert:
needed for properly reverting f3ae5ccf57
Original issue's description:
> Thread maybe-assigned through the bytecodes.
>
> This introduces LoadImmutableContextSlot and LoadImmutableCurrentContextSlot
> bytecodes, which are emitted when reading from never-assigned context slot.
>
> There is a subtlety here: the slot are not immutable, the meaning is
> actually undefined-or-hole-or-immutable.
>
> Review-Url: https://codereview.chromium.org/2655733003
> Cr-Commit-Position: refs/heads/master@{#43000}
> Committed: 17c2dd3886TBR=rmcilroy@chromium.org,bmeurer@chromium.org,neis@chromium.org,jarin@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Review-Url: https://codereview.chromium.org/2680923003
Cr-Commit-Position: refs/heads/master@{#43011}
This introduces LoadImmutableContextSlot and LoadImmutableCurrentContextSlot
bytecodes, which are emitted when reading from never-assigned context slot.
There is a subtlety here: the slot are not immutable, the meaning is
actually undefined-or-hole-or-immutable.
Review-Url: https://codereview.chromium.org/2655733003
Cr-Commit-Position: refs/heads/master@{#43000}
Rename to Construct and ConstructWithSpread, to match the names of
the JSOperators used.
Unfortunately, I can't find a way for auto-formatting to stay happy unless we
change the indentation for the whole BYTECODE_LIST macro.
Review-Url: https://codereview.chromium.org/2663963003
Cr-Commit-Position: refs/heads/master@{#42840}
We can share almost all of the architecture-specific builtin code with super-call-with-spread.
Info to port-writers: The code in CheckSpreadAndPushToStack has changed slightly from what was in Generate_ConstructWithSpread, in that we take the length of the spreaded parameters from the JSArray rather than the FixedArray backing store.
BUG=v8:5511
Review-Url: https://codereview.chromium.org/2649143002
Cr-Commit-Position: refs/heads/master@{#42632}
Reason for revert:
Causes a few bugs caught by clusterfuzz.
Original issue's description:
> [Ignition/turbo] Add a CallWithSpread bytecode.
>
> Also, emit a NewWithSpread bytecode for CallNew AST nodes where possible, rather than desugaring in the parser.
>
> BUG=v8:5511
>
> Review-Url: https://codereview.chromium.org/2629363002
> Cr-Commit-Position: refs/heads/master@{#42455}
> Committed: 4bae43471dTBR=bmeurer@chromium.org,rmcilroy@chromium.org,verwaest@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:5511
Review-Url: https://codereview.chromium.org/2642843002
Cr-Commit-Position: refs/heads/master@{#42470}
Also, emit a NewWithSpread bytecode for CallNew AST nodes where possible, rather than desugaring in the parser.
BUG=v8:5511
Review-Url: https://codereview.chromium.org/2629363002
Cr-Commit-Position: refs/heads/master@{#42455}
Moves constant element/property array building to be deferred for
igition and on-demand for the other compilers, and splits off the
object/array literal depth/flag initialisation from the array building.
BUG=v8:5832
Review-Url: https://codereview.chromium.org/2625873009
Cr-Commit-Position: refs/heads/master@{#42362}
This changes the NewClosure interface descriptor, but ignores
the additional vector/slot arguments for now. The feedback vector
gets larger, as it holds a space for each literal array. A follow-on
CL will constructively use this space.
BUG=v8:5456
Review-Url: https://codereview.chromium.org/2614373002
Cr-Commit-Position: refs/heads/master@{#42146}
Add a feedback vector slot for computed property names in object
and class literals. Introduce new slot kind for storing
computed property names.
Change StaDataPropertyInLiteral to use the accumulator (again), so
we don't exceed Bytecodes::kMaxOperands.
We assume that most computed property names are
symbols. Therefore we should see performance
improvements, even if we deal with monomorphic ICs only.
This CL only collects feedback but does not use
it in Reduce() yet.
BUG=v8:5624
Review-Url: https://codereview.chromium.org/2587393006
Cr-Commit-Position: refs/heads/master@{#42082}
Reason for revert:
Speculative revert because of blocked roll: https://codereview.chromium.org/2596013002/
Original issue's description:
> [TypeFeedbackVector] Root literal arrays in function literals slots
>
> Literal arrays and feedback vectors for a function can be garbage
> collected if we don't have a rooted closure for the function, which
> happens often. It's expensive to come back from this (recreating
> boilerplates and gathering feedback again), and the cost is
> disproportionate if the function was inlined into optimized code.
>
> To guard against losing these arrays when we need them, we'll now
> create literal arrays when creating the feedback vector for the outer
> closure, and root them strongly in that vector.
>
> BUG=v8:5456
>
> Review-Url: https://codereview.chromium.org/2504153002
> Cr-Commit-Position: refs/heads/master@{#41893}
> Committed: 93df094081TBR=bmeurer@chromium.org,mlippautz@chromium.org,mvstanton@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:5456
Review-Url: https://codereview.chromium.org/2597163002
Cr-Commit-Position: refs/heads/master@{#41917}
Literal arrays and feedback vectors for a function can be garbage
collected if we don't have a rooted closure for the function, which
happens often. It's expensive to come back from this (recreating
boilerplates and gathering feedback again), and the cost is
disproportionate if the function was inlined into optimized code.
To guard against losing these arrays when we need them, we'll now
create literal arrays when creating the feedback vector for the outer
closure, and root them strongly in that vector.
BUG=v8:5456
Review-Url: https://codereview.chromium.org/2504153002
Cr-Commit-Position: refs/heads/master@{#41893}
eval() may introduce a scope which needs to be represented as a context at
runtime, e.g.,
eval('var x; let y; ()=>y')
introduces a variable y which needs to have a context allocated for it. However,
when traversing upwards to find the declaration context for a variable which leaks,
as the declaration of x does above, this context has to be understood to not be
a declaration context in sloppy mode.
This patch makes that distinction by introducing a different map for eval-introduced
contexts. A dynamic search for the appropriate context will continue past an eval
context to find the appropriate context. Marking contexts as eval contexts rather
than function contexts required updates in each compiler backend.
BUG=v8:5295, chromium:648719
Review-Url: https://codereview.chromium.org/2435023002
Cr-Commit-Position: refs/heads/master@{#41869}
Encode the PropertyAttribute and whether the function
names must be set as a flag instead of setting two registers.
BUG=v8:5624
Review-Url: https://codereview.chromium.org/2586463002
Cr-Commit-Position: refs/heads/master@{#41812}
This is so that a NotSuperConstructor error is thrown before evaluating the
arguments to the super constructor. Besides updating the runtime function, a
new bytecode GetSuperConstructor is introduced.
BUG=v8:5336
Review-Url: https://codereview.chromium.org/2504553003
Cr-Commit-Position: refs/heads/master@{#41788}
This introduces an explicit struct for the communication channel between
the {ArrayLiteral} AST node and the corresponding runtime methods. Those
methods take a pair of {ElementsKind} as well as an array (can either be
a FixedArray or a FixedDoubleArray) of constant values.
For bonus points it also reduces the size of the involved heap object by
one word (i.e. length field of FixedArray not needed anymore).
R=mvstanton@chromium.org
Review-Url: https://codereview.chromium.org/2581683003
Cr-Commit-Position: refs/heads/master@{#41752}
Templatizes the AccumulatorUsage and OperandType for BytecodeNode creation and
BytecodeRegisterOptimizer::PrepareForBytecode. This allows the compiler to
statically know whether the bytecode being created accesses the accumulator
and what operand types need scaling, avoiding runtime checks in the code.
Also removes BytecodeNode::set_bytecode methods.
Review-Url: https://codereview.chromium.org/2542903003
Cr-Commit-Position: refs/heads/master@{#41706}
Introduces:
- a new AST node representing the GetIterator() algorithm in the specification, to be used by ForOfStatement, YieldExpression (in the case of delegating yield*), and the future `for-await-of` loop proposed in http://tc39.github.io/proposal-async-iteration/#sec-async-iterator-value-unwrap-functions.
- a new opcode (JumpIfJSReceiver), which is useful for `if Type(object) is not Object` checks which are common throughout the specification. This node is easily eliminated by TurboFan.
The AST node is desugared specially in bytecode, rather than manually when building the AST. The benefit of this is that desugaring in the BytecodeGenerator is much simpler and easier to understand than desugaring the AST.
This also reduces parse time very slightly, and allows us to use LoadIC rather than KeyedLoadIC, which seems to have better baseline performance. This results in a ~20% improvement in test/js-perf-test/Iterators micro-benchmarks, which I believe owes to the use of the slightly faster LoadIC as opposed to the KeyedLoadIC in the baseline case. Both produce identical optimized code via TurboFan when the type check can be eliminated, and the load can be replaced with a constant value.
BUG=v8:4280
R=bmeurer@chromium.org, rmcilroy@chromium.org, adamk@chromium.org, neis@chromium.org, jarin@chromium.orgTBR=rossberg@chromium.org
Review-Url: https://codereview.chromium.org/2557593004
Cr-Commit-Position: refs/heads/master@{#41555}
This just calls into a runtime function for implementation currently.
Intermediate step in speeding up constructor calls containing a spread.
The NewWithSpread bytecode will probably end up having different arguments with future CLs - the constructor and the new.target should have their own regs. For now we are calling into the runtime function, so we need the regs together.
BUG=v8:5659
Review-Url: https://codereview.chromium.org/2541113004
Cr-Commit-Position: refs/heads/master@{#41542}
Add bytecode for defining data properties, which initially just calls the runtime function.
BUG=v8:5624
Review-Url: https://codereview.chromium.org/2510743002
Cr-Commit-Position: refs/heads/master@{#41101}
The reasons are:
1) The names dictionaries in the feedback metadata seems to consume a lot of memory
and the idea didn't payoff.
2) The absence of a name parameter blocks data handlers support in LoadGlobalIC.
This CL reverts a part of r37278 (https://codereview.chromium.org/2096653003/).
BUG=chromium:576312, v8:5561
Review-Url: https://codereview.chromium.org/2510653002
Cr-Commit-Position: refs/heads/master@{#41046}
Adds a bytecode to set and retrieve the pending message. This avoids a
runtime call in finally blocks, and also ensures that TurboFan builds a
graph using the SetMessage / LoadMessage nodes instead of inserting a
runtime call.
BUG=chromium:662334
Review-Url: https://codereview.chromium.org/2501503005
Cr-Commit-Position: refs/heads/master@{#41023}
This introduces two new bytecodes LdaModuleVariable and StaModuleVariable,
replacing the corresponding runtime calls.
Support in the bytecode graph builder exists only in the form of runtime calls.
BUG=v8:1569
Review-Url: https://codereview.chromium.org/2471033004
Cr-Commit-Position: refs/heads/master@{#40825}
This is a new bytecode which behaves (for now) exactly like Call,
except that in turbofan graph building we can set the
ConvertReceiverMode to NotNullOrUndefined.
I observe a 1% improvement on Box2D, I'd expect a similar improvement on
other OOP heavy code.
Review-Url: https://codereview.chromium.org/2450243002
Cr-Commit-Position: refs/heads/master@{#40610}
Modify the Bytecode Register Optimizer to be an independent component
rather than part of the BytecodePipeline. This means the BytecodeArrayBuilder
can explicitly call it with register operands when outputting a bytecode
and the Bytecode Register Optimizer doesn't need to work out which operands
are register operands. This also means we don't need to build BytecodeNodes
for Ldar / Star / Mov bytecodes unless they are actually emitted by the
optimizer.
This change also modifies the way the BytecodeArrayBuilder converts
operands to make use of the OperandTypes specified in bytecodes.h.
This avoids having to individually convert operands to their raw output
value before calling Output(...).
BUG=v8:4280
Review-Url: https://codereview.chromium.org/2393683004
Cr-Commit-Position: refs/heads/master@{#40543}
There are only a few occasions where we allocate a register in an outer
expression allocation scope, which makes the costly free-list approach
of the BytecodeRegisterAllocator unecessary. This CL replaces all
occurrences with moves to the accumulator and stores to a register
allocated in the correct scope. By doing this, we can simplify the
BytecodeRegisterAllocator to be a simple bump-pointer allocator
with registers released in the same order as allocated.
The following changes are also made:
- Make BytecodeRegisterOptimizer able to use registers which have been
unallocated, but not yet reused
- Remove RegisterExpressionResultScope and rename
AccumulatorExpressionResultScope to ValueExpressionResultScope
- Introduce RegisterList to represent consecutive register
allocations, and use this for operands to call bytecodes.
By avoiding the free-list handling, this gives another couple of
percent on CodeLoad.
BUG=v8:4280
Review-Url: https://codereview.chromium.org/2369873002
Cr-Commit-Position: refs/heads/master@{#39905}
This CL optimizes the code in BytecodeArrayBuilder and
BytecodeArrayWriter by making the following main changes:
- Move operand scale calculation out of BytecodeArrayWriter to the
BytecodeNode constructor, where the decision on which operands are
scalable can generally be statically decided by the compiler.
- Move the maximum register calculation out of BytecodeArrayWriter
and into BytecodeRegisterOptimizer (which is the only place outside
BytecodeGenerator which updates which registers are used). This
avoids the BytecodeArrayWriter needing to know the operand types
of a node as it writes it.
- Modify EmitBytecodes to use individual push_backs rather than
building a buffer and calling insert, since this turns out to be faster.
- Initialize BytecodeArrayWriter's bytecode vector by reserving 512
bytes,
- Make common functions in Bytecodes constexpr so that they
can be statically calculated by the compiler.
- Move common functions and constructors in Bytecodes and
BytecodeNode to the header so that they can be inlined.
- Change large static switch statements in Bytecodes to const array
lookups, and move to the header to allow inlining.
I also took the opportunity to remove a number of unused helper
functions, and rework some others for consistency.
This reduces the percentage of time spent in making BytecodeArrays
in CodeLoad from ~15% to ~11% according to perf. The
CoadLoad score increase by around 2%.
BUG=v8:4280
Committed: https://crrev.com/b11a8b4d41bf09d6b3d6cf214fe3fb61faf01a64
Review-Url: https://codereview.chromium.org/2351763002
Cr-Original-Commit-Position: refs/heads/master@{#39599}
Cr-Commit-Position: refs/heads/master@{#39637}
Reason for revert:
Prime suspect for roll blocker: https://codereview.chromium.org/2362503002/
Original issue's description:
> [Interpreter] Optimize BytecodeArrayBuilder and BytecodeArrayWriter.
>
> This CL optimizes the code in BytecodeArrayBuilder and
> BytecodeArrayWriter by making the following main changes:
>
> - Move operand scale calculation out of BytecodeArrayWriter to the
> BytecodeNode constructor, where the decision on which operands are
> scalable can generally be statically decided by the compiler.
> - Move the maximum register calculation out of BytecodeArrayWriter
> and into BytecodeRegisterOptimizer (which is the only place outside
> BytecodeGenerator which updates which registers are used). This
> avoids the BytecodeArrayWriter needing to know the operand types
> of a node as it writes it.
> - Modify EmitBytecodes to use individual push_backs rather than
> building a buffer and calling insert, since this turns out to be faster.
> - Initialize BytecodeArrayWriter's bytecode vector by reserving 512
> bytes,
> - Make common functions in Bytecodes constexpr so that they
> can be statically calculated by the compiler.
> - Move common functions and constructors in Bytecodes and
> BytecodeNode to the header so that they can be inlined.
> - Change large static switch statements in Bytecodes to const array
> lookups, and move to the header to allow inlining.
>
> I also took the opportunity to remove a number of unused helper
> functions, and rework some others for consistency.
>
> This reduces the percentage of time spent in making BytecodeArrays
> in CodeLoad from ~15% to ~11% according to perf. The
> CoadLoad score increase by around 2%.
>
> BUG=v8:4280
>
> Committed: https://crrev.com/b11a8b4d41bf09d6b3d6cf214fe3fb61faf01a64
> Cr-Commit-Position: refs/heads/master@{#39599}
TBR=mythria@chromium.org,leszeks@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/2360193003
Cr-Commit-Position: refs/heads/master@{#39612}
This CL optimizes the code in BytecodeArrayBuilder and
BytecodeArrayWriter by making the following main changes:
- Move operand scale calculation out of BytecodeArrayWriter to the
BytecodeNode constructor, where the decision on which operands are
scalable can generally be statically decided by the compiler.
- Move the maximum register calculation out of BytecodeArrayWriter
and into BytecodeRegisterOptimizer (which is the only place outside
BytecodeGenerator which updates which registers are used). This
avoids the BytecodeArrayWriter needing to know the operand types
of a node as it writes it.
- Modify EmitBytecodes to use individual push_backs rather than
building a buffer and calling insert, since this turns out to be faster.
- Initialize BytecodeArrayWriter's bytecode vector by reserving 512
bytes,
- Make common functions in Bytecodes constexpr so that they
can be statically calculated by the compiler.
- Move common functions and constructors in Bytecodes and
BytecodeNode to the header so that they can be inlined.
- Change large static switch statements in Bytecodes to const array
lookups, and move to the header to allow inlining.
I also took the opportunity to remove a number of unused helper
functions, and rework some others for consistency.
This reduces the percentage of time spent in making BytecodeArrays
in CodeLoad from ~15% to ~11% according to perf. The
CoadLoad score increase by around 2%.
BUG=v8:4280
Review-Url: https://codereview.chromium.org/2351763002
Cr-Commit-Position: refs/heads/master@{#39599}
This is some initial cleanup to keep /src clean. The
AccountingAllocator is actually exclusively used by zones and this
common subfolder makes that more clear.
BUG=v8:5409
Review-Url: https://codereview.chromium.org/2344143003
Cr-Commit-Position: refs/heads/master@{#39558}
Adds a fast path for loading DYNAMIC_GLOBAL variables, which are lookup
variables that can be globally loaded, without calling the runtime, as long as
there was no context extension by a sloppy eval along their context chain.
BUG=v8:5263
Review-Url: https://codereview.chromium.org/2347143002
Cr-Commit-Position: refs/heads/master@{#39537}
Adds a fast path for loading DYNAMIC_LOCAL variables, which are lookup
variables that can be context loaded, without calling the runtime, as
long as there was no context extension by a sloppy eval along their
context chain.
BUG=v8:5263
Review-Url: https://codereview.chromium.org/2343633002
Cr-Commit-Position: refs/heads/master@{#39473}
This introduces a new {JumpLoop} bytecode to combine the OSR polling
mechanism modeled by {OsrPoll} with the actual {Jump} performing the
backwards branch. This reduces the overall size and also avoids one
additional dispatch. It also makes sure that OSR polling is only done
within real loops.
R=rmcilroy@chromium.org
BUG=v8:4764
Review-Url: https://codereview.chromium.org/2331033002
Cr-Commit-Position: refs/heads/master@{#39384}
Moves the context chain search loop out of generated bytecode, and into
the (Lda|Ldr|Sda)ContextSlot handler, by passing the context depth in as
an additional operand. This should decrease the bytecode size and
increase performance for deep context chain searches, at the cost of
slightly increasing bytecode size for shallow context access.
Review-Url: https://codereview.chromium.org/2336643002
Cr-Commit-Position: refs/heads/master@{#39378}
This will allow for chaining ScopeInfos together to form the same chains
as contexts chains currently do.
BUG=v8:5215
R=mstarzinger@chromium.org,marja@chromium.org,bmeurer@chromium.org,rmcilroy@chromium.org
Review-Url: https://codereview.chromium.org/2314483002
Cr-Commit-Position: refs/heads/master@{#39192}
Since the extension field is already used for the catch name, store a
ContextExtension there instead.
In the future, this will allow for chaining ScopeInfos together, so we
no longer need a context chain for lazy parsing / compilation.
BUG=v8:5215
R=bmeurer@chromium.org,neis@chromium.org,marja@chromium.org
Review-Url: https://codereview.chromium.org/2302013002
Cr-Commit-Position: refs/heads/master@{#39164}
Collect type feedback in the bytecode handler for 'new' bytecode. The
earlier cl (https://codereview.chromium.org/2153433002/) was reverted
because that implementation did not collect allocation site feedback.
This regressed delta blue by an order of magnitude. This implementation
includes collection of allocation site feedback.
Reland of https://codereview.chromium.org/2190293003/ with a bug fix.
BUG=v8:4280, v8:4780
LOG=N
Review-Url: https://codereview.chromium.org/2225923003
Cr-Commit-Position: refs/heads/master@{#39120}
These JavaScript operators were special hacks to ensure that we always
operate on Smis for the magic for-in index variable, but this never
really worked in the OSR case, because the OsrValue for the index
variable didn't have the proper information (that we have for the
JSForInPrepare in the non-OSR case).
Now that we have loop induction variable analysis and binary operation
hints, we can just use JSLessThan and JSAdd instead with appropriate
Smi hints, which handle the OSR case by inserting Smi checks (that are
always true). Thanks to OSR deconstruction and loop peeling these Smi
checks will be hoisted so they don't hurt the OSR case too much.
Drive-by-change: Rename the ForInDone bytecode to ForInContinue, since
we have to lower it to JSLessThan to get the loop induction variable
goodness.
R=epertoso@chromium.org
BUG=v8:5267
Review-Url: https://codereview.chromium.org/2289613002
Cr-Commit-Position: refs/heads/master@{#38968}
One more bytecode to pass info through to TurboFan.
BUG=v8:4280
LOG=n
Review-Url: https://codereview.chromium.org/2260473003
Cr-Commit-Position: refs/heads/master@{#38726}
Generates a JSCreateWithContext node for TurboFan to optimize.
BUG=v8:4280
LOG=n
Review-Url: https://codereview.chromium.org/2255793002
Cr-Commit-Position: refs/heads/master@{#38723}
Removes all accesses to the Isolate during bytecode generation and the
bytecode pipeline. Adds an DisallowIsolateAccessScope which is used to
enforce this invariant within the BytecodeGenerator.
BUG=v8:5203
Review-Url: https://codereview.chromium.org/2242193002
Cr-Commit-Position: refs/heads/master@{#38716}
Allows us to create a corresponding TurboFan node, so TF can
optimize it.
BUG=v8:4280
LOG=n
Review-Url: https://codereview.chromium.org/2248633002
Cr-Commit-Position: refs/heads/master@{#38651}
Avoids the always generated Star bytecodes after ObjectLiteral.
BUG=v4:4820
LOG=n
Review-Url: https://codereview.chromium.org/2216023003
Cr-Commit-Position: refs/heads/master@{#38480}
Assign feedback slots in the type feedback vector for binary operations.
Update bytecode-generator to use these slots and add them as an operand
to binary operations.
BUG=v8:4280
LOG=N
Review-Url: https://codereview.chromium.org/2209633002
Cr-Commit-Position: refs/heads/master@{#38408}
Reason for revert:
[Sheriff] Fails on nosnap debug:
https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20nosnap%20-%20debug/builds/8403
Original issue's description:
> [Interpreter] Collect type feedback for 'new' in the bytecode handler
>
> Collect type feedback in the bytecode handler for 'new' bytecode. The
> earlier cl (https://codereview.chromium.org/2153433002/) was reverted
> because that implementation did not collect allocation site feedback.
> This regressed delta blue by an order of magnitude. This implementation
> includes collection of allocation site feedback.
>
> BUG=v8:4280, v8:4780
> LOG=N
>
> Committed: https://crrev.com/9d5e6129c4c7f9cbfe81a5fad2a470f219fe137c
> Cr-Commit-Position: refs/heads/master@{#38364}
TBR=bmeurer@chromium.org,rmcilroy@chromium.org,balazs.kilvady@imgtec.com,mythria@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4280, v8:4780
Review-Url: https://codereview.chromium.org/2212343002
Cr-Commit-Position: refs/heads/master@{#38368}
Collect type feedback in the bytecode handler for 'new' bytecode. The
earlier cl (https://codereview.chromium.org/2153433002/) was reverted
because that implementation did not collect allocation site feedback.
This regressed delta blue by an order of magnitude. This implementation
includes collection of allocation site feedback.
BUG=v8:4280, v8:4780
LOG=N
Review-Url: https://codereview.chromium.org/2190293003
Cr-Commit-Position: refs/heads/master@{#38364}
Moves the creation of SharedFunctionInfo for function literals to the
finalization step. This is required for bytecode generation to be
performed off-thread.
BUG=v8:5203
Review-Url: https://codereview.chromium.org/2179303005
Cr-Commit-Position: refs/heads/master@{#38309}
Add a new bytecode to create a function context. The handler inlines
FastNewFunctionContextStub.
BUG=v8:4280
LOG=n
Review-Url: https://codereview.chromium.org/2187523002
Cr-Commit-Position: refs/heads/master@{#38301}
This gets rid of the Star bytecodes that were always dispatched to from
ToObject.
ToObject now outputs to register instead of to the accumulator and
ForInPrepare gets the receiver object from an input register.
BUG=v8:4820
LOG=n
Review-Url: https://codereview.chromium.org/2189463006
Cr-Commit-Position: refs/heads/master@{#38177}
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}
ToName was always generated with a subsequent Star, fuse them.
Requires a few changes in the peephole optimizer as ToName cannot be
elided as easily, but must be replaced by Star.
BUG=v8:4280
LOG=n
Review-Url: https://codereview.chromium.org/2169813002
Cr-Commit-Position: refs/heads/master@{#38019}
Move the logic for allocating the global declaration pair array
from VisitDeclarations to a later step. This is required for
concurrent bytecode generation.
This change requires adding support for reserving fixed
constant pool array entries, which can be later updated
with the value of the literal.
BUG=v8:5203
Review-Url: https://codereview.chromium.org/2167763003
Cr-Commit-Position: refs/heads/master@{#38010}
ToNumber's result is always directly stored to a register using a Star
bytecode. Fuse it into ToNumber.
BUG=v8:4280
LOG=n
Review-Url: https://codereview.chromium.org/2165953002
Cr-Commit-Position: refs/heads/master@{#37976}
This is in preparation to implementing exception prediction for async
functions. Each handler table entry can now predict "caught", "uncaught", or
"promise". The latter indicates that the exception will lead to a promise
rejection.
To mark the relevant try-catch blocks, we add a new native syntax.
try { } %catch (e) { } indicates a TryCatchStatement with the "promise"
prediction.
The previous implementation of using the function to tell the relevant
try-catch apart from inner try-catch blocks will not work for async functions
since these can have inner try-catch blocks inside the same function.
BUG=v8:5167
Review-Url: https://codereview.chromium.org/2161263003
Cr-Commit-Position: refs/heads/master@{#37966}
Reason for revert:
This cl causes a large regression in octane (https://chromeperf.appspot.com/group_report?bug_id=629503). I have to investigate the reason before I can reland this.
Original issue's description:
> [Interpreter] Collect type feedback for 'new' in the bytecode handler
>
> Collect type feedback in the bytecode handler for 'new' bytecode. The
> current implementation does not collect allocation site feedback.
>
> BUG=v8:4280, v8:4780
> LOG=N
>
> Committed: https://crrev.com/1eadc76419b323fb2e55ae9953142f801704aa59
> Cr-Commit-Position: refs/heads/master@{#37862}
TBR=rmcilroy@chromium.org,bmeurer@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4280, v8:4780
Review-Url: https://codereview.chromium.org/2165633003
Cr-Commit-Position: refs/heads/master@{#37872}
Collect type feedback in the bytecode handler for 'new' bytecode. The
current implementation does not collect allocation site feedback.
BUG=v8:4280, v8:4780
LOG=N
Review-Url: https://codereview.chromium.org/2153433002
Cr-Commit-Position: refs/heads/master@{#37862}
Reason for revert:
Breaks the roll, possibly win gn:
https://codereview.chromium.org/2148863002/
Original issue's description:
> [interpreter] Reduce dependencies in bytecodes.{h,cc}
>
> This CL reduces the number of dependencies bytecodes.{h,cc} to facilitate
> generating the bytecode peephole optimizer table during build. Specifically,
> it avoids depending on v8_base.
>
> BUG=v8:4280
> LOG=N
>
> Committed: https://crrev.com/4edebb1cd870ae6c1359ad54f83e618e185883b1
> Cr-Commit-Position: refs/heads/master@{#37715}
TBR=mstarzinger@chromium.org,rmcilroy@chromium.org,oth@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/2151693003
Cr-Commit-Position: refs/heads/master@{#37743}
This CL reduces the number of dependencies bytecodes.{h,cc} to facilitate
generating the bytecode peephole optimizer table during build. Specifically,
it avoids depending on v8_base.
BUG=v8:4280
LOG=N
Review-Url: https://codereview.chromium.org/2135273002
Cr-Commit-Position: refs/heads/master@{#37715}
Collect type feedback in the call bytecode handler. The current
implementation only collects feedback for JS function objects. The other
objects and Array functions do not collect any feedback. They will be
marked Megamorphic.
BUG=v8:4280, v8:4780
LOG=N
Review-Url: https://codereview.chromium.org/2122183002
Cr-Commit-Position: refs/heads/master@{#37700}
The global object can be loaded from the native context and the name can be loaded in the type feedback metadata.
BUG=chromium:576312
Review-Url: https://codereview.chromium.org/2096653003
Cr-Commit-Position: refs/heads/master@{#37278}
In commit b3bfc0bd58, I corrected the source
position of yield-exceptions by not setting the "return position" on returns
that correspond to yields. It turns out that this caused a bug with debug
stepping. The proper fix is to keep the return position on those returns but
additionally attach the yield's source position to the Throw emitted in
VisitYield.
R=rmcilroy@chromium.org, yangguo@chromium.org
BUG=v8:4907
Review-Url: https://codereview.chromium.org/2051783002
Cr-Commit-Position: refs/heads/master@{#36896}
This moves processing of jumps out of bytecode array builder and into
bytecode array writer. This simplifies the pipeline by avoiding having
to flush for offset and patch up offsets in bytecode array builder based
on what was emitted by the bytecode array writer.
This also enables future refactorings to add dead code elimination back
into the pipeline, and move processing of scalable operand sizes to the
end of the pipeline (in the bytecode array writer) rather than having to
deal with scalable operand types throughout pipeline.
BUG=v8:4280,chromium:616064
Review-Url: https://codereview.chromium.org/2035813002
Cr-Commit-Position: refs/heads/master@{#36716}
Eliminating dead code in the bytecode array builder doesn't play nice
with the register elimination optimizer. We should move it to it's own
stage in the optimization pipeline, however doing so would require
refactoring of how we deal with jumps, so for now just remove the dead
code elimination optimization.
BUG=chromium:616064
Review-Url: https://codereview.chromium.org/2030583002
Cr-Commit-Position: refs/heads/master@{#36660}
This change introduces a pipeline for the final stages of
bytecode generation.
The peephole optimizer is made distinct from the BytecodeArrayBuilder.
A new BytecodeArrayWriter is responsible for writing bytecode. It
also keeps track of the maximum register seen and offers a potentially
smaller frame size.
R=rmcilroy@chromium.org
LOG=N
BUG=v8:4280
Review-Url: https://codereview.chromium.org/1947403002
Cr-Commit-Position: refs/heads/master@{#36220}
DevTools uses the debug interrupt to trap on function entry. Without
source position at the stack check, we would get bogus source positions.
R=mstarzinger@chromium.org
BUG=chromium:595646
LOG=N
Review-Url: https://codereview.chromium.org/1925063002
Cr-Commit-Position: refs/heads/master@{#35864}
- Move the check from the BytecodeArrayBuilder destructor, which doesn't get
called, to the ToBytecodeArray function.
- Remove the now empty destructor.
- For generators, bind unused resume point labels somewhere.
R=rmcilroy@chromium.org
BUG=
Review-Url: https://codereview.chromium.org/1924093005
Cr-Commit-Position: refs/heads/master@{#35862}
The new bytecodes replace two runtime functions. They are still unsupported by the bytecode graphbuilder, though.
BUG=v8:4907
LOG=n
Review URL: https://codereview.chromium.org/1904933002
Cr-Commit-Position: refs/heads/master@{#35716}
Improves code coverage of bytecode array builder and constant
array builder.
Fixes initial index for constant pool slice for kQuad operands.
BUG=v8:4280,chromium:599000
LOG=N
TBR=rmcilroy@chromium.org
Review URL: https://codereview.chromium.org/1845313002
Cr-Commit-Position: refs/heads/master@{#35201}
This change introduces wide prefix bytecodes to support wide (16-bit)
and extra-wide (32-bit) operands. It retires the previous
wide-bytecodes and reduces the number of operand types.
Operands are now either scalable or fixed size. Scalable operands
increase in width when a bytecode is prefixed with wide or extra-wide.
The bytecode handler table is extended to 256*3 entries. The
first 256 entries are used for bytecodes with 8-bit operands,
the second 256 entries are used for bytecodes with operands that
scale to 16-bits, and the third group of 256 entries are used for
bytecodes with operands that scale to 32-bits.
LOG=N
BUG=v8:4747,v8:4280
Review URL: https://codereview.chromium.org/1783483002
Cr-Commit-Position: refs/heads/master@{#34955}
The function literal consists of a list of statements. Each statement
is associated with a statement position including break location. The
only exception to this rule is when the function immediately throws if
scope resolution found an illegal redeclaration. Make sure that we add a
break location for this case as well. The debugger relies on this.
R=bmeurer@chromium.org, vogelheim@chromium.org
BUG=v8:4690
LOG=N
Review URL: https://codereview.chromium.org/1759603002
Cr-Commit-Position: refs/heads/master@{#34422}
Similar to fullcodegen, Ignition now also marks a for-in statement as
slow (via the TypeFeedbackVector) when we have to call %ForInFilter,
i.e. we either have no enumeration cache or the receiver map changes
during an iteration of the for-in map.
R=mstarzinger@chromium.org
BUG=v8:3650
LOG=n
Review URL: https://codereview.chromium.org/1755563002
Cr-Commit-Position: refs/heads/master@{#34391}
We used to emit debug break location on block entry. This cannot be
ported to the interpreted as we do not emit bytecode for block entry.
This made no sense to begin with though, but accidentally added
break locations for var declarations.
With this change, the debugger no longer breaks at var declarations
without initialization. This is in accordance with the fact that the
interpreter does not emit bytecode for uninitialized var declarations.
Also fix the bytecode to match full-codegen's behavior wrt return
positions:
- there is a break location before the return statement, with the source
position of the return statement.
- right before the actual return, there is another break location. The
source position points to the end of the function.
R=rmcilroy@chromium.org, vogelheim@chromium.orgTBR=rossberg@chromium.org
BUG=v8:4690
LOG=N
Review URL: https://codereview.chromium.org/1744123003
Cr-Commit-Position: refs/heads/master@{#34388}
Reason for revert:
It is not a good idea to call CallICStub from the builtin. It might be sensitive to the frame structure. Constructing a internal frame might cause problems. It is much better to inline the code related to the type feedback vector into the builtin.
Original issue's description:
> [Interpreter] Implements calls through CallICStub in the interpreter.
>
> Calls are implemented through CallICStub to collect type feedback. Adds
> a new builtin called InterpreterPushArgsAndCallIC that pushes the
> arguments onto stack and calls CallICStub.
>
> Also adds two new bytecodes CallIC and CallICWide to indicate calls have to
> go through CallICStub.
>
> MIPS port contributed by balazs.kilvady.
>
> BUG=v8:4280, v8:4680
> LOG=N
>
> Committed: https://crrev.com/20362a2214c11a0f2ea5141b6a79e09458939cec
> Cr-Commit-Position: refs/heads/master@{#34244}
TBR=rmcilroy@chromium.org,mvstanton@chromium.org,mstarzinger@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4280, v8:4680
Review URL: https://codereview.chromium.org/1731253003
Cr-Commit-Position: refs/heads/master@{#34252}
Calls are implemented through CallICStub to collect type feedback. Adds
a new builtin called InterpreterPushArgsAndCallIC that pushes the
arguments onto stack and calls CallICStub.
Also adds two new bytecodes CallIC and CallICWide to indicate calls have to
go through CallICStub.
MIPS port contributed by balazs.kilvady.
BUG=v8:4280, v8:4680
LOG=N
Review URL: https://codereview.chromium.org/1688283003
Cr-Commit-Position: refs/heads/master@{#34244}
This CL introduces two new bytecodes TailCall and TailCallWide.
BUG=v8:4698,v8:4687
LOG=N
Review URL: https://codereview.chromium.org/1698273003
Cr-Commit-Position: refs/heads/master@{#34083}
Adds support for ES6 super keyword and performing loads, stores, and
calls to super class members.
Implements SetHomeObject and enables ThisFunctionVariable.
BUG=v8:4280,v8:4682
LOG=N
Review URL: https://codereview.chromium.org/1689573004
Cr-Commit-Position: refs/heads/master@{#33977}
Adds JumpIfNotHoleConstant and JumpIfNotHoleConstantWide bytecodes
and removes JumpIfHole bytecode.
In situations with large numbers of constants, the generator would
fail because an 8-bit constant could not be reserved for
JumpIfHole/JumpIfNotHole and so a 16-bit constant would be reserved.
Then when patching the bytecode the patcher would discover there was
no wide constant variant of the emitted jump.
BUG=v8:4280,v8:4680
LOG=N
Review URL: https://codereview.chromium.org/1697473002
Cr-Commit-Position: refs/heads/master@{#33952}
This replaces the bytecode in question with a runtime call within the
bytecode stream. The tradeoff is to safe one bytecode opcode for more
expensive encoding of lookup slot deletion.
R=rmcilroy@chromium.org
Review URL: https://codereview.chromium.org/1690913002
Cr-Commit-Position: refs/heads/master@{#33907}
This allows us to remove the somewhat awkward BuildLoadObjectField
from the BytecodeGraphBuilder and also allows us to simplify the
bytecode stream for class literals.
R=oth@chromium.org
Review URL: https://codereview.chromium.org/1678103002
Cr-Commit-Position: refs/heads/master@{#33820}
Adds implementation and tests to support const/let variables in the
interpreter.
BUG=v8:4280,v8:4679
LOG=N
Review URL: https://codereview.chromium.org/1634153002
Cr-Commit-Position: refs/heads/master@{#33819}
Replace the somewhat awkward RestParamAccessStub, which would always
call into the runtime anyway with a proper FastNewRestParameterStub,
which is basically based on the code that was already there for strict
arguments object materialization. But for rest parameters we could
optimize even further (leading to 8-10x improvements for functions with
rest parameters), by fixing the internal formal parameter count:
Every SharedFunctionInfo has a formal_parameter_count field, which
specifies the number of formal parameters, and is used to decide whether
we need to create an arguments adaptor frame when calling a function
(i.e. if there's a mismatch between the actual and expected parameters).
Previously the formal_parameter_count included the rest parameter, which
was sort of unfortunate, as that meant that calling a function with only
the non-rest parameters still required an arguments adaptor (plus some
other oddities). Now with this CL we fix, so that we do no longer
include the rest parameter in that count. Thereby checking for rest
parameters is very efficient, as we only need to check whether there is
an arguments adaptor frame, and if not create an empty array, otherwise
check whether the arguments adaptor frame has more parameters than
specified by the formal_parameter_count.
The FastNewRestParameterStub is written in a way that it can be directly
used by Ignition as well, and with some tweaks to the TurboFan backends
and the CodeStubAssembler, we should be able to rewrite it as
TurboFanCodeStub in the near future.
Drive-by-fix: Refactor and unify the CreateArgumentsType which was
different in TurboFan and Ignition; now we have a single enum class
which is used in both TurboFan and Ignition.
R=jarin@chromium.org, rmcilroy@chromium.orgTBR=rossberg@chromium.org
BUG=v8:2159
LOG=n
Review URL: https://codereview.chromium.org/1676883002
Cr-Commit-Position: refs/heads/master@{#33809}
Moves the stack check from the function entry trampoline to instead be
after function activation using an explicit StackCheck bytecode. Also
add stack checks on back edges of loops.
BUG=v8:4280,v8:4678
LOG=N
Review URL: https://codereview.chromium.org/1665853002
Cr-Commit-Position: refs/heads/master@{#33730}
Unifies the meaning of kRegCount8 and kRegCount16 across bytecodes.
Call and CallJSRuntime had a slightly different use of the register
count operand. From this change forth, register count operands are
always based off of the previous register operand.
BUG=v8:4280,v8:4675
LOG=N
Review URL: https://codereview.chromium.org/1659023002
Cr-Commit-Position: refs/heads/master@{#33707}
Moves the temporary register allocator out of the bytecode array
builder into TemporaryRegisterAllocator class and adds unittests.
Particular must be taken around the translation window boundary
motivating the addition of tests.
Also adds a Clear() method to IdentityMap() which is called by
the destructor. This allows classes to hold an IdentityMap if
they are zone allocated. Classes must call Clear() before the zone
is re-cycled or face v8 heap corruption.
BUG=v8:4280,v8:4675
LOG=N
Review URL: https://codereview.chromium.org/1651133002
Cr-Commit-Position: refs/heads/master@{#33686}
Introduces the concept of transfer direction to register operands. This
enables the register translator to emit exactly the moves that a
bytecode having it's register operands translated needs.
BUG=v8:4280,v8:4675
LOG=N
Review URL: https://codereview.chromium.org/1633153002
Cr-Commit-Position: refs/heads/master@{#33544}
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}
This implements a first version of exception handler table construction
within the interpreter. Note that the local control flow for try-catch
and try-finally statements is still off, and also stack unwinding does
not yet respect interpreter frames. But generated handler tables should
be populated correctly already.
R=oth@chromium.org
BUG=v8:4674
LOG=n
Review URL: https://codereview.chromium.org/1607433005
Cr-Commit-Position: refs/heads/master@{#33400}
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}
Removes assignment hazard scope. Reverts back to the naive scheme of
allocating a temporary for every variable load. It was decided to revert it
because the current implementation does not handle logical expressions,
ternary operators, visiting objects in named/keyed loads. Also, we wanted
to evaluate alternate approaches and choose one when we have a mechanism
to measure performance.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1576403004
Cr-Commit-Position: refs/heads/master@{#33269}
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}
Consecutive registers are allocated in two passes. First we "reserve"
a set of registers and these get allocated when we actually use them.
If we request for a temporary register before we use all the consecutive
registers, the earlier implementation does not gaurantee that it allocates
outside the reservation for consecutive registers. This could cause problems
for example, in call_func(a, b++, c). This cl fixes
TemporaryRegisterScope::NewRegister, to return a new temporary register
outside the reservation for consecutive registers.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1531273002
Cr-Commit-Position: refs/heads/master@{#33005}
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}
This change adds support for local control flow when building graphs
from bytecode. The change ensures loop emitted from the bytecode
generator are in natural order so the only back branches are for loops.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1502243002
Cr-Commit-Position: refs/heads/master@{#32911}
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}
an optomization to remove redundant cast operations.
1. Adds an optimization to remove redundant ToBoolean and ToName operations.
2. Adds implementation and tests for cast operatorts to bytecode graph builder.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1468003002
Cr-Commit-Position: refs/heads/master@{#32408}
Moves all files related to AST and scopes into ast/,
and all files related to scanner & parser to parsing/.
Also eliminates a couple of spurious dependencies.
R=mstarzinger@chromium.org
BUG=
Review URL: https://codereview.chromium.org/1481613002
Cr-Commit-Position: refs/heads/master@{#32351}
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}
