They did the same thing.
Change-Id: I6b63762352dae2dce58fb3a6182af52cd0aadef6
Reviewed-on: https://chromium-review.googlesource.com/c/1470126
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59566}
... as there's no search involved and there are never multiple names.
Change-Id: Ice88c4d98195e74f6540926b0a1199df62b42da2
Reviewed-on: https://chromium-review.googlesource.com/c/1466645
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59532}
Merging the temporary HeapObjectPtr back into HeapObject.
Bug: v8:3770
Change-Id: I5bcd23ca2f5ba862cf5b52955dca143e531c637b
Reviewed-on: https://chromium-review.googlesource.com/c/1386492
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58410}
along with subclasses: Tuple2, Tuple3, FeedbackCell, AccessorPair.
The latter two can be separated out later if desired.
Bug: v8:5402
Change-Id: I4e1a6d2621cc6f96b5da208cff0da7cd5de91672
Reviewed-on: https://chromium-review.googlesource.com/c/1371038
Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58251}
We do not have to collect feedback for function calls in one-shot code.
This CL avoids allocating CallICslots for each function call by
emitting CallNoFeedback bytecodes. We save one CallICSlot (two entries
in feedback vector) per function call in One-shot.
Bug: v8:8072
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Change-Id: Ic2580e5972acd5124c2e71d540985736ce797fe8
Reviewed-on: https://chromium-review.googlesource.com/1178051
Commit-Queue: Chandan Reddy <chandanreddy@google.com>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55951}
E.g., "ToWeakHeapObject" was misleading, since it didn't convert to a weak heap
object, instead returned a weakly pointed heap object. Change the function names
(in this case, to "GetHeapObjectIfWeak") to reflect this.
Also make casts explicit, if a MaybeObject is an Object, we can call cast<Object>().
Previous version: https://chromium-review.googlesource.com/1219025
BUG=v8:7308
TBR=ishell@chromium.org, ulan@chromium.org, ahaas@chromium.org, yangguo@chromium.org, tebbi@chromium.org
Change-Id: I503d4a2a3a68f85e9e02e1c2f9fc1c4187c8e9a1
Reviewed-on: https://chromium-review.googlesource.com/1226800
Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55934}
This reverts commit ad72d19516.
Reason for revert: Build failures on *san
Original change's description:
> [in-place weak refs] Fix MaybeObject function names
>
> E.g., "ToWeakHeapObject" was misleading, since it didn't convert to a weak heap
> object, instead returned a weakly pointed heap object. Change the function names
> (in this case, to "GetHeapObjectIfWeak") to reflect this.
>
> Also make casts explicit, if a MaybeObject is an Object, we can call cast<Object>().
>
> BUG=v8:7308
>
> Change-Id: I4ef078572b4f4415afe7e2e706d3bd684e16e47d
> Reviewed-on: https://chromium-review.googlesource.com/1219025
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Commit-Queue: Marja Hölttä <marja@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#55906}
TBR=ulan@chromium.org,marja@chromium.org,yangguo@chromium.org,ahaas@chromium.org,tebbi@chromium.org,ishell@chromium.org
Change-Id: I054b578518e3f6fd7dbcddf0b56cc018726c1e7a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7308
Reviewed-on: https://chromium-review.googlesource.com/1226874
Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55918}
E.g., "ToWeakHeapObject" was misleading, since it didn't convert to a weak heap
object, instead returned a weakly pointed heap object. Change the function names
(in this case, to "GetHeapObjectIfWeak") to reflect this.
Also make casts explicit, if a MaybeObject is an Object, we can call cast<Object>().
BUG=v8:7308
Change-Id: I4ef078572b4f4415afe7e2e706d3bd684e16e47d
Reviewed-on: https://chromium-review.googlesource.com/1219025
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55906}
In future the RO_SPACE root accessors in Heap will become private, so
instead convert them all to use ReadOnlyRoots.
Bug: v8:7786
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: I2f2c031c03d56d360ef940fc925e0583e6ae31dc
Reviewed-on: https://chromium-review.googlesource.com/1125720
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54202}
- Make FeedbackVector backing store a WeakFixedArray.
- "feedback" is always strong but "extra" might be weak.
- Whenever the handler stored in FeedbackVector is a WeakCell to a transition
Map, replace it with an in-place weak reference.
For a more detailed description of the changes, see the design doc
https://docs.google.com/document/d/1P8cIme2wKszdYt64ObAiuh6pXgLnrrn80Hpl1ejJbOU/edit#heading=h.ijx1oculrikp
BUG=v8:7308
Change-Id: I72c5cf6597ef24d4c22a1fe8e25b67ca196d4ec8
Reviewed-on: https://chromium-review.googlesource.com/1027855
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53051}
There is no good reason to have the meat of most objects' initialization
logic in heap.cc, all wrapped by the CALL_HEAP_FUNCTION macro. Instead,
this CL changes the protocol between Heap and Factory to be AllocateRaw,
and all object initialization work after (possibly retried) successful
raw allocation happens in the Factory.
This saves about 20KB of binary size on x64.
Original review: https://chromium-review.googlesource.com/c/v8/v8/+/959533
Originally landed as r52416 / f9a2e24bbc
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: Id072cbe6b3ed30afd339c7e502844b99ca12a647
Reviewed-on: https://chromium-review.googlesource.com/1000540
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52492}
This reverts commit f9a2e24bbc.
Reason for revert: gc stress failures not all fixed by follow up.
Original change's description:
> [cleanup] Refactor the Factory
>
> There is no good reason to have the meat of most objects' initialization
> logic in heap.cc, all wrapped by the CALL_HEAP_FUNCTION macro. Instead,
> this CL changes the protocol between Heap and Factory to be AllocateRaw,
> and all object initialization work after (possibly retried) successful
> raw allocation happens in the Factory.
>
> This saves about 20KB of binary size on x64.
>
> Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
> Change-Id: Icbfdc4266d7be8b48d2fe085f03411743dc6a0ca
> Reviewed-on: https://chromium-review.googlesource.com/959533
> Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Hannes Payer <hpayer@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#52416}
TBR=jkummerow@chromium.org,yangguo@chromium.org,mstarzinger@chromium.org,hpayer@chromium.org
Change-Id: Idbbc53478742f3e9525eee83342afc6aedae122f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/999414
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52420}
There is no good reason to have the meat of most objects' initialization
logic in heap.cc, all wrapped by the CALL_HEAP_FUNCTION macro. Instead,
this CL changes the protocol between Heap and Factory to be AllocateRaw,
and all object initialization work after (possibly retried) successful
raw allocation happens in the Factory.
This saves about 20KB of binary size on x64.
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: Icbfdc4266d7be8b48d2fe085f03411743dc6a0ca
Reviewed-on: https://chromium-review.googlesource.com/959533
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52416}
This is preparatory cleanup work for eventually tracking the functions
(rather than concrete closures) in the CALL_IC, also for builtins like
the default PromiseCapability [[Resolve]] and [[Reject]] functions. It
adds a new FeedbackCell type, which is used by JSFunctions consistently
now to reference the feedback vector (or undefined if not the function
is not compiled yet or is a native/asm.js function).
This also changes the calling convention for FastNewClosure builtin and
the JSCreateClosure operator in TurboFan to carry the FeedbackCell here
instead of the parent FeedbackVector and the slot index. In addition we
eliminate the now unused %InterpreterNewClosure runtime function.
Bug: v8:2206, v8:7253, v8:7310
Change-Id: Ib4ce456e276e0273e57c163dcdd0b33abf863656
Reviewed-on: https://chromium-review.googlesource.com/928403
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51474}
This fixes a bug which causes the call count to change when
changing the speculation mode.
Bug: v8:7127
Change-Id: Icb43bd9ac392a5be4df154cb1e5cd4365013efc4
Reviewed-on: https://chromium-review.googlesource.com/911575
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51227}
The FeedbackNexus classes initially were one-to-one with IC classes,
but over time this got out of date. We also found Nexus' useful, so
we made more classes even for cases that weren't ICs.
The inheritence and polymorphism became confusing and led to
duplication. Better, to just talk about a (single) FeedbackNexus.
Bug: v8:7344
Change-Id: I509dc9657895d56c3859de6e6589695cdff9e73e
Reviewed-on: https://chromium-review.googlesource.com/890452
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Reviewed-by: Franziska Hinkelmann <franzih@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50997}
This patch adds a field for the speculation mode to Call
nodes, and passes the speculation mode from the CallIC
to the Call node in the byte code graph builder.
Bug: v8:7127
Change-Id: I89fa10643b46143b36776de1d5ba6ebe3fa2c878
Reviewed-on: https://chromium-review.googlesource.com/814537
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49965}
This CL uses bits of the call count as flags according
to CallCountField and SpeculationModeField defined in
CallICNexus.
Bug: v8:7127
Change-Id: I3f64c1807d61410f9029b46b9a59a1fcaa5a0a3b
Reviewed-on: https://chromium-review.googlesource.com/808926
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49959}
Moves the feedback vector slot allocation out of ast-numbering and into
bytecode generation directly. This has a couple of benifits, including reduced
AST size, avoid code duplication and reduced feedback vector sizes in many cases
due to only allocating slots when needed. Also removes AstProperties since
this is no longer needed.
AstNumbering is now only used to allocate suspend ids for generators.
BUG=v8:6921
Change-Id: I103e8593c94ef5b2e56c34ef4f77bd6e7d64796f
Reviewed-on: https://chromium-review.googlesource.com/722959
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48757}
This CL adds support to optimize for..in in fast enum-cache mode to the
same degree that it was optimized in Crankshaft, without adding the same
deoptimization loop that Crankshaft had with missing enum cache indices.
That means code like
for (var k in o) {
var v = o[k];
// ...
}
and code like
for (var k in o) {
if (Object.prototype.hasOwnProperty.call(o, k)) {
var v = o[k];
// ...
}
}
which follows the https://eslint.org/docs/rules/guard-for-in linter
rule, can now utilize the enum cache indices if o has only fast
properties on the receiver, which speeds up the access o[k]
significantly and reduces the pollution of the global megamorphic
stub cache.
For example the micro-benchmark in the tracking bug v8:6702 now runs
faster than ever before:
forIn: 1516 ms.
forInHasOwnProperty: 1674 ms.
forInHasOwnPropertySafe: 1595 ms.
forInSum: 2051 ms.
forInSumSafe: 2215 ms.
Compared to numbers from V8 5.8 which is the last version running with
Crankshaft
forIn: 1641 ms.
forInHasOwnProperty: 1719 ms.
forInHasOwnPropertySafe: 1802 ms.
forInSum: 2226 ms.
forInSumSafe: 2409 ms.
and V8 6.0 which is the current stable version with TurboFan:
forIn: 1713 ms.
forInHasOwnProperty: 5417 ms.
forInHasOwnPropertySafe: 5324 ms.
forInSum: 7556 ms.
forInSumSafe: 11067 ms.
It also improves the throughput on the string-fasta benchmark by
around 7-10%, and there seems to be a ~5% improvement on the
Speedometer/React benchmark locally.
For this to work, the ForInPrepare bytecode was split into
ForInEnumerate and ForInPrepare, which is very similar to how it was
handled in Fullcodegen initially. In TurboFan we introduce a new
operator LoadFieldByIndex that does the dynamic property load.
This also removes the CheckMapValue operator again in favor of
just using LoadField, ReferenceEqual and CheckIf, which work
automatically with the EscapeAnalysis and the
BranchConditionElimination.
Bug: v8:6702
Change-Id: I91235413eea478ba77ace7bd14bb2f62e155dd9a
Reviewed-on: https://chromium-review.googlesource.com/645949
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47768}
* Avoid "using namespace" statements, which trigger clang's -Wheader-hygiene
warnings in jumbo builds.
* Undefine created macros at the end of source files.
BUG=chromium:746958
Change-Id: I5d25432c314437f607b0e1be22765a6764267ba6
Reviewed-on: https://chromium-review.googlesource.com/610962
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Mostyn Bramley-Moore <mostynb@opera.com>
Cr-Commit-Position: refs/heads/master@{#47347}
Calling the Array constructor is an edge case, and we don't seem to
benefit from doing the AllocationSite tracking there as well. In fact
it's a lot of complexity and somewhat blocking the more important
optimization of the subclass constructors.
This is an attempt to nuke the CallIC support for AllocationSites. If
it regresses something important, we'll have to find another way.
Bug: v8:6399
Change-Id: I56f6da29679c516f0a5c3161c2696fc2b8762176
Reviewed-on: https://chromium-review.googlesource.com/600968
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47158}
Instead of having feedback vector as a subtype of FixedArray with
reserved slots, make it a first-class variable-sized object with a
fixed-size header. This allows us to compress counters to ints in the
header, rather than forcing them to be Smis.
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: Icc5f088ffbc2e2651b845bc71ea42060639e3e48
Reviewed-on: https://chromium-review.googlesource.com/585129
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46935}
This CL introduces a new type, MapHandles, which is a STL vector of Handle<Map>.
It is now used everywhere where lists of Handle<Maps> are required, replacing
usages of V8's internal List type.
Also-By: franzih@chromium.org
BUG=v8:6333,v8:6325
LOG=N
Review-Url: https://codereview.chromium.org/2809923002
Cr-Commit-Position: refs/heads/master@{#45211}
... and stop checking that the native contexts of maps recorded in feedback vector
match function's native context - the feedback vector machinery already guarantees
that.
BUG=v8:6325
Change-Id: Iacd3f3a5f703694ff57b774b9658e186ad66641b
Reviewed-on: https://chromium-review.googlesource.com/490084
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44982}
Most callers passed kFinalizeIncrementalMarkingMask, so use that as
a default argument (not using default argument syntax to avoid including
heap.h in cctest.h).
Change-Id: I904f1eb3a0f5fdbe63eab16f6a6f01d04618645d
Reviewed-on: https://chromium-review.googlesource.com/488104
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44950}
The former will handle stores to global variables, lets and undeclared
variables. The latter will handle named stores to explicit receiver.
BUG=chromium:576312, v8:5561
Change-Id: I335fa21db47c3d001da8cc79fa8cb6f8abcbb7e2
Reviewed-on: https://chromium-review.googlesource.com/458639
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44085}
... 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}
... and don't clear ICs during GC. The IC clearing used to prevent memory
leaks but it's not necessary anymore because all the handlers that need
to embed objects already use weak cells.
This CL unblocks inlining of IC dispatchers into bytecode handlers.
BUG=v8:5917
Change-Id: I229b9ba8dba44f431dfbe8ac5370d855e3e84dd6
Reviewed-on: https://chromium-review.googlesource.com/442127
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43209}
Previously, both type feedback vector and the shared function info
of a function points to the matching type feedback metadata. This
makes finding the shared function info of a type feedback vector
difficult.
Instead, we now point the type feeback vector to the shared function
info, and find the metadata through the shared function info.
Also remove the obsolete empty type feedback vector.
R=hpayer@chromium.org, mvstanton@chromium.org
BUG=v8:5808
Review-Url: https://codereview.chromium.org/2672363002
Cr-Commit-Position: refs/heads/master@{#43026}
... and TypeFeedbackMetadata to FeedbackMetadata.
BUG=
Change-Id: I2556d1c2a8f37b8cf3d532cc98d973b6dc7e9e6c
Reviewed-on: https://chromium-review.googlesource.com/439244
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#42999}
TypeFeedbackVectors are strongly rooted by a closure. However, in modern
JavaScript closures are created and abandoned more freely. An important
closure may not be present in the root-set at time of garbage collection,
even though we've cached optimized code and use it regularly. For
example, consider leaf functions in an event dispatching system. They may
well be "hot," but tragically non-present when we collect the heap.
Until now, we've relied on a weak root to cache the feedback vector in
this case. Since there is no way to signal intent or relative importance,
this weak root is as susceptible to clearing as any other weak root at
garbage collection time.
Meanwhile, the feedback vector has become more important. All of our
ICs store their data there. Literal and regex boilerplates are stored there.
If we lose the vector, then we not only lose optimized code built from
it, we also lose the very feedback which allowed us to create that optimized
code. Therefore it's vital to express that dependency through the root
set.
This CL does this by creating a strong link to a feedback
vector at the instantiation site of the function closure.
This instantiation site is in the code and feedback vector
of the outer closure.
BUG=v8:5456
Review-Url: https://codereview.chromium.org/2674593003
Cr-Commit-Position: refs/heads/master@{#42953}
They have the same lifetime. It's a match!
Both structures are native context dependent and dealt with (creation,
clearing, gathering feedback) at the same time. By treating the spaces used
for literal boilerplates as feedback vector slots, we no longer have to keep
track of the materialized literal count elsewhere.
A follow-on CL removes even more parser infrastructure related to this count.
BUG=v8:5456
Review-Url: https://codereview.chromium.org/2655853010
Cr-Commit-Position: refs/heads/master@{#42771}
