The baseline compiler needs to know the depth in order to access the
parent block. This is a small CL, but anything that can land before the
big baseline CL reduced the complexity of the latter.
R=ahaas@chromium.org
Bug: v8:6600
Change-Id: I2e29cc974908438266adb4301026dfe5fbfb1990
Reviewed-on: https://chromium-review.googlesource.com/677301
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48112}
There are some mysterious, unreproducible CHECK failures (inconsistent
data). Add more information onto the stack (and thus, to minidumps) for
debugging them.
BUG=v8:5516,chromium:766693
Change-Id: Ic1ebc3036957ede4e3e1c1d287479897e54e40ed
Reviewed-on: https://chromium-review.googlesource.com/677294
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48111}
In the current implementation, compilation would fail because
operator<< is not defined for enum classes. For others, the compiler
finds more than one operator<<, so it fails because it's ambiguous.
This CL fixes this by printing the integer value for enums, uses the
operator<< for all values that support it, and prints "<unprintable>"
otherwise.
Also, lots of unit tests.
R=ishell@chromium.org
Bug: v8:6837
Change-Id: I895ed226672aa07213f9605e094b87af186ec2e4
Reviewed-on: https://chromium-review.googlesource.com/671016
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48110}
And add some tests for (seemingly) previously uncovered cases.
The additional check for unreachable code is not needed any more, since
polymorphic stack values get assigned a specific type on their first
use or validation anyway. Hence the first entry in the br_table will
assign specific types to all polymorphic stack values, and type checking
will fail if later entries do not match.
R=rossberg@chromium.orgCC=titzer@chromium.org
Change-Id: I1d0f91f927a2aa5186f874112e91ebffa1f1b3a7
Reviewed-on: https://chromium-review.googlesource.com/675405
Reviewed-by: Andreas Rossberg <rossberg@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48109}
This fix is two-fold:
1) Incremental UTF-8 decoding: Unify incorrect UTF-8 handling between V8 and
Blink.
Incremental UTF-8 decoding used to allow some overlong sequences / invalid code
points which Blink treated as errors. This caused the decoder and the Blink
UTF-8 decoder to produce a different number of bytes, resulting in random
failures when scripts were streamed (especially, this was detected by the
skipping inner functions feature which adds CHECKs against expected function
positions).
2) Non-incremental UTF-8 decoding: return the correct amount of invalid characters.
According to the encoding spec ( https://encoding.spec.whatwg.org/#utf-8-decoder
), the first byte of an overlong sequence / invalid code point generates an
invalid character, and the rest of the bytes are not processed (i.e., pushed
back to the byte stream). When they're handled, they will look like lonely
continuation bytes, and will generate an invalid character each.
As a result, an overlong 4-byte sequence should generate 4 invalid characters
(not 1).
This is a potentially breaking change, since the (non-incremental) UTF-8
decoding is exposed via the API (String::NewFromUtf8). The behavioral difference
happens when the client is passing in invalid UTF-8 (containing overlong /
surrogate sequences).
However, afaict, this doesn't change the semantics of any JavaScript program:
according to the ECMAScript spec, the program is a sequence of Unicode code
points, and there's no way to invoke the UTF-8 decoding functionalities from
inside JavaScript. Though, this changes the behavior of d8 when decoding source
files which are invalid UTF-8.
This doesn't change anything related to URI decoding (it already throws
exceptions for overlong sequences / invalid code points).
BUG: chromium:765608, chromium:758236, v8:5516
Bug:
Change-Id: Ib029f6a8e87186794b092e4e8af32d01cee3ada0
Reviewed-on: https://chromium-review.googlesource.com/671020
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Franziska Hinkelmann <franzih@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48105}
By adding a per test source file namespace, we can avoid a lot of
symbol collisions in jumbo builds.
While we're at it, let's remove some "using" statements that also
cause trouble.
Bug: chromium:746958
Change-Id: I6f8a723e1ba5905888638e0687b23193f3f012ca
Reviewed-on: https://chromium-review.googlesource.com/676803
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Mostyn Bramley-Moore <mostynb@opera.com>
Cr-Commit-Position: refs/heads/master@{#48102}
Memory instantiate on initialize should always patch memory
references. If memory references are not patched for no initial
memory, on subsequent calls to grow_memory in wasm functions for
instances that share a module, the references will be patched
without resetting cloned compiled values to their correct initial
values.
BUG=chromium:763439
Change-Id: I666439332379b02aa344e99d61ef3dc88ab86cc8
Reviewed-on: https://chromium-review.googlesource.com/674707
Reviewed-by: Mircea Trofin <mtrofin@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48097}
- Changes x64 AssembleSwap to push/pop to swap 128 bit slot swaps.
- Reorders instructions to simplify 32/64 bit FP slot swaps.
- Refactor ia32 version of this, eliminating OffsetOperand in favor of
existing ToOperand.
Bug: v8:6020
Change-Id: Ie0ae4c581c9aeb88ee786797851c3c77d5210a3d
Reviewed-on: https://chromium-review.googlesource.com/669748
Commit-Queue: Bill Budge <bbudge@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48096}
For consistency with surrounding handlified code. No change in
functionality intended.
Change-Id: I8501514ce9caf94fc7e6fb45162fcfd3d730efcd
Reviewed-on: https://chromium-review.googlesource.com/671671
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48095}
Along with BigInt.prototype. Their functions only have skeleton
implementations. The purpose of this change is to make it easier
to gradually increase test coverage (e.g. for toString(radix)).
Of course this is still behind the --harmony-bigint flag.
Bug: v8:6791
Change-Id: Ic307fd9165c56ac782fba18d648ce893daaa718f
Reviewed-on: https://chromium-review.googlesource.com/671209
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48094}
There is no support to emulate atomic WASM operations on big-endian
platforms, since this would require bit swapping as a part of atomic
operations. Therefore, cctest/test-run-wasm-atomics/* will be skipped.
TEST=cctest/test-run-wasm-atomics/*
BUG=
Change-Id: I1a8b085f816f615011788092e6fc8a8390678382
Reviewed-on: https://chromium-review.googlesource.com/671010
Reviewed-by: Ivica Bogosavljevic <ivica.bogosavljevic@imgtec.com>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Ivica Bogosavljevic <ivica.bogosavljevic@imgtec.com>
Cr-Commit-Position: refs/heads/master@{#48093}
Do this by deleting code after calls to V8_Fatal() (either through
UNREACHABLE() or FATAL()). Comments suggest that the returns there
were needed to make a compiler happy, but all compilers seem to be
happy with this change too. My guess is that either
https://codereview.chromium.org/1393023003 which marked V8_Fatal()
as noreturn, or https://chromium-review.googlesource.com/#/c/544845/
which switched to the C++11 spelling of noreturn, fixed the warnings
that the explicit code after V8_Fatal() was supposed to silence.
There's one more warning in src/compiler/machine-graph-verifier.cc,
but fixing that changes behavior. I asked about that one in
https://codereview.chromium.org/2573573004/#msg27 instead.
Bug: chromium:346399
Change-Id: Ie9519d5432bdeaaf382e8390d8254d3b79e622e4
Reviewed-on: https://chromium-review.googlesource.com/669803
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48092}
This fixes a few leftovers where we use WASM_EXEC_TEST, but then
unconditionally execute the compiled code, and also changes more tests
to use WASM_EXEC_TEST, hence run in both the interpreter and compiled
code.
Once we have land the baseline compiler, those tests will also execute
in baseline compilation mode.
R=ahaas@chromium.org
Bug: v8:6600
Change-Id: I79598df21a7538934306e01ca6593f05afe19ed3
Reviewed-on: https://chromium-review.googlesource.com/672528
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48091}
This reverts commit f2cd10db14.
Reason for revert: Blocks the roll https://chromium-review.googlesource.com/c/chromium/src/+/674623
Original change's description:
> Reland "[Memory] Move VirtualMemory out of base:: platform."
>
> This is a reland of 4dd293d922
> Original change's description:
> > [Memory] Move VirtualMemory out of base:: platform.
> >
> > - Moves base::VirtualMemory to v8::internal::VirtualMemory.
> > - Makes VirtualMemory platform-independent by moving internals to new
> > OS:: static methods, for each platform.
> >
> > This will make it easier to delegate memory management in VirtualMemory
> > to V8::Platform, so that embedders like Blink can override it. We can't
> > depend on V8::Platform in base/platform.
> >
> > Bug: chromium:756050
> > Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
> > Change-Id: Iadfe230b6850bd917727a373f277afded9883adf
> > Reviewed-on: https://chromium-review.googlesource.com/653214
> > Commit-Queue: Bill Budge <bbudge@chromium.org>
> > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#48048}
>
> Bug: chromium:756050
> Change-Id: Ib492c7c69f1833be127a571808301e96b84b8aa2
> Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
> Reviewed-on: https://chromium-review.googlesource.com/671125
> Commit-Queue: Bill Budge <bbudge@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48084}
TBR=bbudge@chromium.org,ulan@chromium.org,hpayer@chromium.org,mlippautz@chromium.org,scottmg@chromium.org
Change-Id: I04176d77ca9ad8315b0e1bb2b21f40f2c8ab9536
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:756050
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/674843
Reviewed-by: Michael Hablich <hablich@chromium.org>
Commit-Queue: Michael Hablich <hablich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48088}
The work list should be empty in the case we are not tearing down
during incremental marking. Explicitly clear during incremental marking
and rely on DCHECKs for the other case.
Bug: chromium:758570
Change-Id: Iecc8935f0cbfda67f0e7afde42930050e7c94d2d
Reviewed-on: https://chromium-review.googlesource.com/674504
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48087}
When var_type_feedback is nullptr and {lhs} is not a String,
rhs_instance_type is not needed.
Bug:
Change-Id: Ia39aa39ec7ad0063d2fb9b01fd326d7993ab4d26
Reviewed-on: https://chromium-review.googlesource.com/659340
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48086}
This is a reland of 4dd293d922
Original change's description:
> [Memory] Move VirtualMemory out of base:: platform.
>
> - Moves base::VirtualMemory to v8::internal::VirtualMemory.
> - Makes VirtualMemory platform-independent by moving internals to new
> OS:: static methods, for each platform.
>
> This will make it easier to delegate memory management in VirtualMemory
> to V8::Platform, so that embedders like Blink can override it. We can't
> depend on V8::Platform in base/platform.
>
> Bug: chromium:756050
> Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
> Change-Id: Iadfe230b6850bd917727a373f277afded9883adf
> Reviewed-on: https://chromium-review.googlesource.com/653214
> Commit-Queue: Bill Budge <bbudge@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48048}
Bug: chromium:756050
Change-Id: Ib492c7c69f1833be127a571808301e96b84b8aa2
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/671125
Commit-Queue: Bill Budge <bbudge@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48084}
Now hopefully getting it right, but still leaving in the confusing
flag implications.
Bug: v8:6520,chromium:766162
Change-Id: Idc6dca012bf0c9777b4a75cf424410ce5914c885
Reviewed-on: https://chromium-review.googlesource.com/671022
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48082}
Runtime profiler uses bytecode array size for the tiering up decisions.
Bytecode array size includes the header size as well. Inlining
heuristics use bytecode array length instead. Bytecode array length
is just the size of bytecode not inlcuding any headers. This change
is to keep both of them in sync to avoid confusion. Also, the header
contains several pointers and hence the size changes depending on the
size of kPointerSize.
Bug:
Change-Id: I22a9cf5e0bb9d6853c6a8be8d69c9ff459418a0d
Reviewed-on: https://chromium-review.googlesource.com/670724
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48081}
Use the (D)CHECK_{EQ,NE,GT,...} macros instead of (D)CHECK with an
embedded comparison. This gives better error messages and also does the
right comparison for signed/unsigned mismatches.
This will allow us to reenable the readability/check cpplint check.
R=ahaas@chromium.org
Bug: v8:6837
Change-Id: Ic8966dfeacf02b2684eeef23fde99ec2be4ed81e
Reviewed-on: https://chromium-review.googlesource.com/671364
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48080}
Use the (D)CHECK_{EQ,NE,GT,...} macros instead of (D)CHECK with an
embedded comparison. This gives better error messages and also does the
right comparison for signed/unsigned mismatches.
This will allow us to reenable the readability/check cpplint check.
R=jgruber@chromium.org
Bug: v8:6837
Change-Id: I9c489ac0e1b15fd4789c37fd32c9d3c76121a288
Reviewed-on: https://chromium-review.googlesource.com/671343
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48079}
Removes
- SequentialMarkingDeque
- The ability to handle marking deque overflow
- BlackToGrey transitions
We switched to a different marking work list on M61 that fails
in OOM upon failing to allocate Segments used in the work list.
Bug: chromium:758570
Change-Id: I66e2ab912271bf84b085dccc9b4bdd96076b64fb
Reviewed-on: https://chromium-review.googlesource.com/632676
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48078}
This CL refactors allocation & reservation logic into a new
DefaultSerializerAllocator class. In upcoming work, this will be
further extended by a custom allocator for builtin serialization.
Additionally, this cleans up a bunch of cosmetics (encapsulation and
other nits).
Bug: v8:6624
Change-Id: Ibcf12a525c8fcb26d9c16b7a12fd598c37a0e10a
Reviewed-on: https://chromium-review.googlesource.com/650357
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48077}
This is primarily to aid in testing the Wasm out of bounds trap handler. We
keep track of how many faults have been recovered by the Wasm trap handler. This
count is exposed to JavaScript through a testing-only runtime function. This
allows tests to verify whether the trap handler is actually running.
Bug: v8:5277
Change-Id: Ie8037a36d84eb08166c6e40c7225d912683d5786
Reviewed-on: https://chromium-review.googlesource.com/665968
Commit-Queue: Eric Holk <eholk@chromium.org>
Reviewed-by: Mircea Trofin <mtrofin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48076}
Sanitize imports before we start the instance building process. This
avoids the possibility of exiting to JS while building instances,
and allowing JS to observe an inconsistent state of the wasm world -
e.g. incomplete specialization chains.
We now validate we never exit to JS during that process.
Bug: chromium:766260
Change-Id: I34930c8b70bdac16af464b3f62a2b6a38107acb3
Reviewed-on: https://chromium-review.googlesource.com/671480
Commit-Queue: Mircea Trofin <mtrofin@chromium.org>
Reviewed-by: Eric Holk <eholk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48074}
Promises can sometimes be resolved after the RealmScope has been destroyed, such
as when a Wasm compile job finishes after the script main has finished. If the
Promise.then function refers to Realm.current, we were getting a use-after free
error when it would search for the list of realms. This change also zeros out
realm_count_ in addition to deleting the realms_ so that RealmFind will not
reference freed memory.
Bug: chromium:761710
Change-Id: I2d42997f363b284ccc5f4b225d3f59e0361e68d6
Reviewed-on: https://chromium-review.googlesource.com/671923
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Eric Holk <eholk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48073}
Also store the variable directly on ClassLiteral, as the proxy serves
as a useless form of indirection.
Bug: v8:6092
Change-Id: If0182a808cde4e349c1bf5a003a1ecee5bd14b13
Reviewed-on: https://chromium-review.googlesource.com/667800
Reviewed-by: Mythri Alle <mythria@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48072}
Chromium has rolled the Fuchsia SDK, so this can be removed now, and
the new zx_, etc. names used exclusively.
Bug: chromium:765754
Change-Id: I8bd60239da7a05e62d3b8d5209e1cfe898d8052a
Reviewed-on: https://chromium-review.googlesource.com/671769
Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Scott Graham <scottmg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48071}
This is a reland of aabb893a32
Original change's description:
> fuchsia: Set up for 3-sided roll to convert Magenta->Zircon
>
> Fuchsia changed their kernel name from Magenta to Zircon and all the
> functions and defines along with it. In order to be able to roll the SDK
> in Chromium, we first need to land with this define added in v8, so that
> can roll in to Chromium, then roll the Fuchsia SDK with this magic
> define set (CHROMIUM_ROLLING_MAGENTA_TO_ZIRCON), then actually update v8
> to reference zx_ instead of mx_ and roll that again.
>
> Chromium-side for reference: https://chromium-review.googlesource.com/c/chromium/src/+/669139
>
> Bug: chromium:765754, chromium:707030
> Change-Id: I4ed5027f455d2346f431e7c700e87693348d5b79
> Reviewed-on: https://chromium-review.googlesource.com/668751
> Reviewed-by: Bill Budge <bbudge@chromium.org>
> Commit-Queue: Scott Graham <scottmg@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48047}
TBR=bbudge@chromium.org
Bug: chromium:765754, chromium:707030
Change-Id: Ib6e99ca418af527014622614d07d295b6110f9d5
Reviewed-on: https://chromium-review.googlesource.com/670944
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48067}
The bug occurred when we detected an erroneous char late, and put the last
character in a chunk into the "incomplete char" buffer. It was not correctly
retrieved when seeking.
BUG=v8:6836
Change-Id: I8ca946dfdb39244c5ca0bdcebe047047010b3a07
Reviewed-on: https://chromium-review.googlesource.com/670729
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Daniel Vogelheim <vogelheim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48066}
SetForceInline flag is no longer used. This flag was added for
inlining some of the javascript builtins. They are now ported to
TurboFan builtins. This cl removes SetForceInline runtime function
and the corresponding bits in the SharedFunctionInfo. Also update
inlining heuristics to not look for this bit.
Bug: v8:6682
Change-Id: Ie8df9648332b765a556e24609c38b4e55b810527
Reviewed-on: https://chromium-review.googlesource.com/668436
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48065}
This reverts commit 2b15425b0c.
Reason for revert: Re-enabling escape analysis after merging the flag change to 6.1.
Original change's description:
> [turbofan] Temporarily turn off escape analysis.
>
> Bug: chromium:765433
> Change-Id: Iecc9540f6305bc24a0a5210c149b55403b9ce09d
> Reviewed-on: https://chromium-review.googlesource.com/667106
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48032}
TBR=mstarzinger@chromium.org,jarin@chromium.org
# Not skipping CQ checks because original CL landed > 1 day ago.
Bug: chromium:765433
Change-Id: Icac44fd76e2965df1e143700941b628ea7a69166
Reviewed-on: https://chromium-review.googlesource.com/670864
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48064}
This is now implemented as a build-time flag.
Change-Id: I10db18725ca6837ae04032725582717233b2c2e5
Reviewed-on: https://chromium-review.googlesource.com/670728
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48063}