- Creates a memory management API in v8::internal, which corresponds
to the existing one in base::OS.
- Implements the new API in terms of the old one.
- Changes all usage of the base::OS API to the one in v8::internal. This
includes all tests, except platform and OS tests.
- Makes OS:: methods private.
- Moves all LSAN calls into the v8::internal functions.
Bug: chromium:756050
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: Iaa3f022e3e12fdebf937f3c76b6c6455014beb8a
Reviewed-on: https://chromium-review.googlesource.com/794856
Commit-Queue: Bill Budge <bbudge@chromium.org>
Reviewed-by: Eric Holk <eholk@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50139}
* DisableInlineAllocationSteps was a blunt hammer added to work around
tests that needed to avoid artificially lower limits imposed by
observers. PauseAllocationObserversScope can properly disable step on
a temporary basis.
* Modify tests. Remove DisableInlineAllocationSteps.
This exposed a bug in allocation observers: we were not doing a step
when a fresh page is added.
Fix this by moving the step into UpdateAllocationInfo. We should be
doing a step (and keeping top_on_previous_step_ consistent) whenever
we move move top(). UpdateAllocationInfo is the correct place for this
rather than the callers of UpdateAllocationInfo.
Bug:
Change-Id: I2edc238dc2e73bf9a2e9738c2a9b50efcac5cbf0
Reviewed-on: https://chromium-review.googlesource.com/821052
Commit-Queue: Ali Ijaz Sheikh <ofrobots@google.com>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50052}
Currently Page::ShrinkToHighWaterMark checks that there is only one
filler in the to-be-freed area at the end of the page. This does not
hold if an allocation observer is active.
We should instead check that the to-be-freed area does not contain
allocated objects and will not contain allocated objects:
1) Following chain of fillers we arrive at the end of the page.
2) The free list of the page is empty.
This patch also changes PagedSpace::ResetFreeList to evict free list
entries of each page, instead of just reseting the global free list.
It also removes invalidation of free list categories.
Now FreeList::EvictFreeListItems simply evicts free list entries without
invalidating free list categories.
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I6051578ec2c91c9614d14c7a6ce188d2db5ace3b
Reviewed-on: https://chromium-review.googlesource.com/822571
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50040}
The tests illustrate the use of v8::EmbedderHeapTracer.
Bug: v8:7176
Change-Id: Ic383c968691fddb0ec96d66cb33ee42b9c304a75
Reviewed-on: https://chromium-review.googlesource.com/811924
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49934}
This patch normalizes the casing of hexadecimal digits in escape
sequences of the form `\xNN` and integer literals of the form
`0xNNNN`.
Previously, the V8 code base used an inconsistent mixture of uppercase
and lowercase.
Google’s C++ style guide uses uppercase in its examples:
https://google.github.io/styleguide/cppguide.html#Non-ASCII_Characters
Moreover, uppercase letters more clearly stand out from the lowercase
`x` (or `u`) characters at the start, as well as lowercase letters
elsewhere in strings.
BUG=v8:7109
TBR=marja@chromium.org,titzer@chromium.org,mtrofin@chromium.org,mstarzinger@chromium.org,rossberg@chromium.org,yangguo@chromium.org,mlippautz@chromium.org
NOPRESUBMIT=true
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I790e21c25d96ad5d95c8229724eb45d2aa9e22d6
Reviewed-on: https://chromium-review.googlesource.com/804294
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49810}
In a recent CL I introduced module-level CodeSpaceMemoryModificationScopes,
which means that the number of CodeSpaceMemoryModificationScopes which
are opened aside from TurboFan compilation is not linear in the number
of functions anymore. In that CL, however, I did not remove scopes which
became obsolete. This CL removes now these obsolete scopes, and
introduces some scopes where shared code was used from outside the
compilation logic.
R=mstarzinger@chromium.org, clemensh@chromium.org
Bug: chromium:787731
Change-Id: I37d514efa3a4b10adb7008986a9c91e4557ce618
Reviewed-on: https://chromium-review.googlesource.com/790490
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49662}
- Eliminates CommitRegion and UncommitRegion methods, replacing them with
calls to SetPermissions.
- Makes a similar change to the API of VirtualMemory.
- This changes system calls from mmap to mprotect on most POSIX platforms.
Bug: chromium:756050
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: Ib10f8293c9398c6c1e729cd7d686b7c97e6a5d75
Reviewed-on: https://chromium-review.googlesource.com/769679
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49552}
This ensures that the {Code::builtin_index} field is only set during
allocation of new {Code} objects, making this field truly immutable.
R=jgruber@chromium.org
BUG=v8:6792
Change-Id: Ic793346976183149e2d077e92cb9da3c925ea865
Reviewed-on: https://chromium-review.googlesource.com/774439
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49414}
There's three common situations in which we need to create JSFunction
objects. 1) from the compiler, 2) from tests, and 3) everything else
(mostly during bootstrapping).
This is an attempt to simplify case 3), which previously relied on
several Factory::NewFunction overloads where it was not clear how the
semantics of each overload differed.
This CL removes all but one overload, and packs arguments into a new
NewFunctionArgs helper class.
It also removes the hacks around
SFI::set_lazy_deserialization_builtin_id by explicitly passing
builtin_id into Factory::NewSharedFunctionInfo.
Drive-by-fix: Properly set is_constructor hint in
SimpleCreateSharedFunctionInfo.
Bug: v8:6624
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: Ica94d95e72e443055db5e7ff9e8cdf4115201ef1
Reviewed-on: https://chromium-review.googlesource.com/757094
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49224}
This reverts commit 32f30f6338.
Reason for revert: broken Fuchsia build, https://logs.chromium.org/v/?s=chromium%2Fbb%2Fclient.v8%2FV8_Fuchsia%2F460%2F%2B%2Frecipes%2Fsteps%2Fcompile%2F0%2Fstdout
Original change's description:
> [platform] check return values from memory operations
>
> This change adds DCHECKs for calls such as mprotect, as well as marking some of
> the memory allocation and deallocation routines as V8_MUST_USE_RESULT. This
> additional checking gives us more useful information for failure in the presence
> of, for example, address space exhaustion.
>
> Bug:
> Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
> Change-Id: I5bc76c1da6160262d3d556fea49d284ddd4e02c5
> Reviewed-on: https://chromium-review.googlesource.com/721267
> Commit-Queue: Eric Holk <eholk@chromium.org>
> Reviewed-by: Hannes Payer <hpayer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#49164}
TBR=hpayer@chromium.org,mlippautz@google.com,eholk@chromium.org
Change-Id: Ie4b57b45c801dcce7884645f50ff74f833de6dc4
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/756137
Reviewed-by: Eric Holk <eholk@chromium.org>
Commit-Queue: Eric Holk <eholk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49165}
This change adds DCHECKs for calls such as mprotect, as well as marking some of
the memory allocation and deallocation routines as V8_MUST_USE_RESULT. This
additional checking gives us more useful information for failure in the presence
of, for example, address space exhaustion.
Bug:
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I5bc76c1da6160262d3d556fea49d284ddd4e02c5
Reviewed-on: https://chromium-review.googlesource.com/721267
Commit-Queue: Eric Holk <eholk@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49164}
This adds code-space modification scopes to all sites that still rely on
mutation of {Code} objects after allocation. Currently some scopes also
potentially are in performance-critical places that might regress if the
protection would be enabled in its current form.
R=clemensh@chromium.org
BUG=v8:6792
Change-Id: I8d511e0e452324dae027e50a9da8e6f77224b86f
Reviewed-on: https://chromium-review.googlesource.com/751521
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49147}
Sweeping a page while currently scavenging it is broken as the scavenger
might override the slot it is currently processing.
Bug: chromium:779503
Change-Id: I224a144b84e97a956bf10ba018132c2713e8f78d
Reviewed-on: https://chromium-review.googlesource.com/752081
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49092}
During iteration of the optimized code list to process weak slots, we
need to clear the next_code_link in the CodeDataContainer of a dying
code object because the CodeDataContainer can still be alive.
BUG=v8:6792
Change-Id: Iec5f7430a4097cb622de2157bdec2a7d539dbba0
Reviewed-on: https://chromium-review.googlesource.com/751663
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49087}
Rename |property_attributes| to |initial_property_attributes| and ensure
that it is used as a storage of values only for AccessorInfos installed in
API Templates (i.e. ObjectTemplate and FunctionTemplate).
When an AccessorInfo is installed directly into an existing JS object
(via JSObject::SetAccessor) or into a DescriptorArray (when certain V8
objects' shapes are configured) it is not necessary to thread attributes
being set through the AccessorInfo instance.
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: Ibe61026f08c42549756f694129a286635ffe5769
Reviewed-on: https://chromium-review.googlesource.com/730425
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48978}
Both the top_ pointer and the top_on_previous_step_ pointer can be one
byte beyond the current page. Page::FromAddress call should take that
into account.
Bug: chromium:777177
Change-Id: I9cbb5bc6eab932afc6d0c915fd70a9a7b20ba62c
Reviewed-on: https://chromium-review.googlesource.com/738204
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48962}
This is a reland of eeaffa9f33
Original change's description:
> [objects] Introduce {CodeDataContainer} object type.
>
> This introduces the {CodeDataContainer} as a container for all mutable
> fields associated with a {Code} object. For now only the kind-specific
> flags are moved, but more fields can/will be moved gradually. The goal
> is to make all fields in the {Code} header be immutable eventually.
>
> R=jarin@chromium.org
> BUG=v8:6792
>
> Change-Id: I2eeba893afaba877fb6117e1f18371898c3a175e
> Reviewed-on: https://chromium-review.googlesource.com/732987
> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
> Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48902}
Bug: v8:6792
Change-Id: I31a127df4bb8ee5fedb4d73755df4deae6e1d352
Reviewed-on: https://chromium-review.googlesource.com/738109
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48928}
This reverts commit eeaffa9f33.
Reason for revert: Breaks msan compile (uninitialized value in snapshot):
https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20arm64%20-%20sim%20-%20MSAN/builds/17824
Original change's description:
> [objects] Introduce {CodeDataContainer} object type.
>
> This introduces the {CodeDataContainer} as a container for all mutable
> fields associated with a {Code} object. For now only the kind-specific
> flags are moved, but more fields can/will be moved gradually. The goal
> is to make all fields in the {Code} header be immutable eventually.
>
> R=jarin@chromium.org
> BUG=v8:6792
>
> Change-Id: I2eeba893afaba877fb6117e1f18371898c3a175e
> Reviewed-on: https://chromium-review.googlesource.com/732987
> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
> Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48902}
TBR=mstarzinger@chromium.org,jarin@chromium.org
Change-Id: I74fe833b074752d640cff4aa4680f250e1bd8780
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6792
Reviewed-on: https://chromium-review.googlesource.com/738029
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48904}
This introduces the {CodeDataContainer} as a container for all mutable
fields associated with a {Code} object. For now only the kind-specific
flags are moved, but more fields can/will be moved gradually. The goal
is to make all fields in the {Code} header be immutable eventually.
R=jarin@chromium.org
BUG=v8:6792
Change-Id: I2eeba893afaba877fb6117e1f18371898c3a175e
Reviewed-on: https://chromium-review.googlesource.com/732987
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48902}
- Introduce the new union type UnionType<T1,T2>, used for Number and
Numeric. Similarly, PairType<T1,T2> is used for a Turbofan operation
with two results. Further details in the design doc:
https://docs.google.com/document/d/10foP3m7SDWyFfbda96iEJ_XYOLQdd32AeoP8SD1cTcs/edit#heading=h.bghdno28mr7u
- Allow to derive the MachineType from a static type.
This allows to select the right MachineType when performing a
load/store.
- Disallow casts (UncheckedCast() or CAST()) when the target and
origin type have no overlap.
New cast ReinterpretCast() is an UncheckedCast without this check.
- Caveat of this CL: Checked casts (CAST()) are not possible for
UnionType<T1,T2> with the exception of Number (due to the existence
of Number in OBJECT_TYPE_LIST and the existence of an IsNumber()
function in the runtime).
Bug: v8:6949
Change-Id: I21a683d1341f69cebd8a347f545b454b463c52ad
Reviewed-on: https://chromium-review.googlesource.com/723320
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48796}
This allocates and populates potential source position table before the
underlying {Code} objects is allocated. It essentially makes the field
holding said table immutable after allocation.
R=verwaest@chromium.org
BUG=v8:6792
Change-Id: If35462688a1b502f28ae84f73b82b5df5005735f
Reviewed-on: https://chromium-review.googlesource.com/727895
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48781}
This allocates and populates potential deoptimization data arrays before
the underlying {Code} objects is allocated. It aims at making the field
holding said data immutable after allocation. Note that we still mutate
this field during deoptimization.
R=verwaest@chromium.org
BUG=v8:6792
Change-Id: Id0c2cfb65e782d7292d2df6bff41c54b2b8c3351
Reviewed-on: https://chromium-review.googlesource.com/725704
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48738}
This allocates and populates potential exception handler tables before
the underlying {Code} objects is allocated. It essentially makes the
field holding said table immutable after allocation.
R=verwaest@chromium.org
BUG=v8:6792
Change-Id: I52ca374d40e3a72a4de022aca10faead6422db79
Reviewed-on: https://chromium-review.googlesource.com/723299
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48677}
This CL fixes all occurences that don't require special OWNER reviews,
or can be reviewed by Michi.
After this one, we should be able to reenable the readability/check
cpplint check.
R=mstarzinger@chromium.org
Bug: v8:6837, v8:6921
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng;master.tryserver.v8:v8_linux_noi18n_rel_ng
Change-Id: Ic81d68d5534eaa795b7197fed5c41ed158361d62
Reviewed-on: https://chromium-review.googlesource.com/721120
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48670}
The test was reading from undefined stack addresses instead of creating
a string filled with characters that look like a new space pointer.
Bug: v8:6953
Change-Id: I2c0a9034076012746bd70325a4f21c63f4c264fa
Reviewed-on: https://chromium-review.googlesource.com/725322
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48668}
This code is never used, and we don't right trim TypedArrays.
Bug:
Change-Id: Ic3e32b194fb10ecd067449c755b1982c87c98257
Reviewed-on: https://chromium-review.googlesource.com/721541
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48623}
Pause sweeper tasks when entering the Scavenger. In future CLs this
enables removing the page lock for the Scavenger.
CQ_INCLUDE_TRYBOTS=master.tryserver.v8:v8_linux64_tsan_rel;master.tryserver.v8:v8_linux64_tsan_concurrent_marking_rel_ng;master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
Bug: v8:6923, chromium:774108
Change-Id: Idcb7e14b94704dead70c33a49e67047b88bb6c4c
Reviewed-on: https://chromium-review.googlesource.com/718200
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48603}
New code should use nullptr instead of NULL.
This patch updates existing use of NULL to nullptr where applicable,
making the code base more consistent.
BUG=v8:6928,v8:6921
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng;master.tryserver.v8:v8_linux_noi18n_rel_ng
Change-Id: I4687f5b96fcfd88b41fa970a2b937b4f6538777c
Reviewed-on: https://chromium-review.googlesource.com/718338
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48557}
When hitting objects that are allocated in the most recent lienar
allocation area, the concurrent marker currently has to bail out to the
main thread.
However, we only have to delay processing those objects until we are at
a safepoint, e.g. IM::Step(). With this change we flush those
on-hold-objects back to the shared queue upon performing an incremental
marking step.
Bug: chromium:694255
Change-Id: I25647d0fc581a5c4de0346bc394dc51062f65f70
Reviewed-on: https://chromium-review.googlesource.com/707315
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48424}
Each concurrent marking task maintains task_state[i]->marked_bytes.
When a task finishes, its local counter is flushed into global
total_marked_bytes_ atomic counter.
Bug: chromium:694255
Change-Id: I629467385e80bf229e06a4231673ceb5ef8e4aea
Reviewed-on: https://chromium-review.googlesource.com/704823
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48374}
This makes the test robust for stress GC flags.
Bug:
Change-Id: Ica65987f0ee09fbdb4aab233dea4c51db5b19459
Reviewed-on: https://chromium-review.googlesource.com/702436
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48313}
This is a reland of ec952aaa68.
Included is a fix that ensures that top_on_previous_step_ is cleared when we
release a page.
Original change's description:
> Reland "[profiler] proper observation of old space inline allocations"
>
> This is a reland of 672a41c3ca
> Original change's description:
> > [profiler] proper observation of old space inline allocations
> >
> > Bug: chromium:633920
> > Change-Id: I9a2f4a89f6b9c0f63cb3b166b06a88a12f0a203c
> > Reviewed-on: https://chromium-review.googlesource.com/631696
> > Commit-Queue: Ali Ijaz Sheikh <ofrobots@google.com>
> > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#48043}
>
> Bug: chromium:633920
> Change-Id: I6fe743d31b8ff26f3858488d4c014c62d3c85add
> Reviewed-on: https://chromium-review.googlesource.com/671127
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Commit-Queue: Ali Ijaz Sheikh <ofrobots@google.com>
> Cr-Commit-Position: refs/heads/master@{#48085}
Bug: chromium:633920
Change-Id: I8a0dcc4eaffc1f1d3ac5b3f8d344001cdae36606
Reviewed-on: https://chromium-review.googlesource.com/677407
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Ali Ijaz Sheikh <ofrobots@google.com>
Cr-Commit-Position: refs/heads/master@{#48141}
