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Revert "Implement and use VectorSegment to avoid repeated allocation of ZoneVector properties."

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This reverts commit d3104923b2.

Reason for revert: Breaks win debug, causes lots of timeouts.
https://build.chromium.org/p/client.v8/builders/V8%20Win64%20-%20debug/builds/20387

Original change's description:
> Implement and use VectorSegment to avoid repeated allocation of ZoneVector properties.
> 
> The parser holds a single vector whose backing storage is reused in calls
> to ParseJsonObject, so that once we reach the peak number of unstored
> properties no more allocations are required.
> 
> This improves performance of parsing inputs like those in Speedometer VanillaJS
> by about 2% in my local measurement, and would presumably do better on more
> pathological inputs.
> 
> This should also have the side effect of reducing peak memory usage at this time
> slightly, since we do fewer zone allocations which cannot be freed until the
> parse finishes.
> 
> Bug: chromium:771227
> Change-Id: I8aa1514b37a74f82539f95f94292c8fa1582d66a
> Reviewed-on: https://chromium-review.googlesource.com/789511
> Reviewed-by: Camillo Bruni <cbruni@chromium.org>
> Reviewed-by: Marja Hölttä <marja@chromium.org>
> Commit-Queue: Jeremy Roman <jbroman@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#49693}

TBR=jbroman@chromium.org,marja@chromium.org,cbruni@chromium.org

Change-Id: I5b198aeffed6f1543f6110709dc74b311d4ba144
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:771227
Reviewed-on: https://chromium-review.googlesource.com/796151
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49705}
This commit is contained in:
Michael Achenbach 2017-11-29 10:57:34 +00:00 committed by Commit Bot
parent 3200cc600c
commit 32033f4f4f
2 changed files with 9 additions and 44 deletions
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48
src/json-parser.cc
View File

@ -20,38 +20,6 @@
namespace v8 {
namespace internal {
namespace {
// A vector-like data structure that uses a larger vector for allocation, and
// provides limited utility access. The original vector must not be used for the
// duration, and it may even be reallocated. This allows vector storage to be
// reused for the properties of sibling objects.
template <typename Container>
class VectorSegment {
public:
using value_type = typename Container::value_type;
explicit VectorSegment(Container* container)
: container_(*container), begin_(container->size()) {}
~VectorSegment() { container_.resize(begin_); }
Vector<const value_type> GetVector() const {
return Vector<const value_type>(&container_[begin_],
container_.size() - begin_);
}
template <typename T>
void push_back(T&& value) {
container_.push_back(std::forward<T>(value));
}
private:
Container& container_;
const typename Container::size_type begin_;
};
} // namespace
MaybeHandle<Object> JsonParseInternalizer::Internalize(Isolate* isolate,
Handle<Object> object,
Handle<Object> reviver) {
@ -143,8 +111,7 @@ JsonParser<seq_one_byte>::JsonParser(Isolate* isolate, Handle<String> source)
zone_(isolate_->allocator(), ZONE_NAME),
object_constructor_(isolate_->native_context()->object_function(),
isolate_),
position_(-1),
properties_(&zone_) {
position_(-1) {
source_ = String::Flatten(source_);
pretenure_ = (source_length_ >= kPretenureTreshold) ? TENURED : NOT_TENURED;
@ -366,7 +333,7 @@ Handle<Object> JsonParser<seq_one_byte>::ParseJsonObject() {
factory()->NewJSObject(object_constructor(), pretenure_);
Handle<Map> map(json_object->map());
int descriptor = 0;
VectorSegment<ZoneVector<Handle<Object>>> properties(&properties_);
ZoneVector<Handle<Object>> properties(zone());
DCHECK_EQ(c0_, '{');
bool transitioning = true;
@ -457,7 +424,7 @@ Handle<Object> JsonParser<seq_one_byte>::ParseJsonObject() {
DCHECK(!transitioning);
// Commit the intermediate state to the object and stop transitioning.
CommitStateToJsonObject(json_object, map, properties.GetVector());
CommitStateToJsonObject(json_object, map, &properties);
JSObject::DefinePropertyOrElementIgnoreAttributes(json_object, key, value)
.Check();
@ -465,7 +432,7 @@ Handle<Object> JsonParser<seq_one_byte>::ParseJsonObject() {
// If we transitioned until the very end, transition the map now.
if (transitioning) {
CommitStateToJsonObject(json_object, map, properties.GetVector());
CommitStateToJsonObject(json_object, map, &properties);
} else {
while (MatchSkipWhiteSpace(',')) {
HandleScope local_scope(isolate());
@ -513,14 +480,15 @@ Handle<Object> JsonParser<seq_one_byte>::ParseJsonObject() {
template <bool seq_one_byte>
void JsonParser<seq_one_byte>::CommitStateToJsonObject(
Handle<JSObject> json_object, Handle<Map> map,
Vector<const Handle<Object>> properties) {
ZoneVector<Handle<Object>>* properties) {
JSObject::AllocateStorageForMap(json_object, map);
DCHECK(!json_object->map()->is_dictionary_map());
DisallowHeapAllocation no_gc;
DescriptorArray* descriptors = json_object->map()->instance_descriptors();
for (int i = 0; i < properties.length(); i++) {
Handle<Object> value = properties[i];
int length = static_cast<int>(properties->size());
for (int i = 0; i < length; i++) {
Handle<Object> value = (*properties)[i];
// Initializing store.
json_object->WriteToField(i, descriptors->GetDetails(i), *value);
}

5
src/json-parser.h
View File

@ -144,7 +144,7 @@ class JsonParser BASE_EMBEDDED {
Zone* zone() { return &zone_; }
void CommitStateToJsonObject(Handle<JSObject> json_object, Handle<Map> map,
Vector<const Handle<Object>> properties);
ZoneVector<Handle<Object>>* properties);
Handle<String> source_;
int source_length_;
@ -157,9 +157,6 @@ class JsonParser BASE_EMBEDDED {
Handle<JSFunction> object_constructor_;
uc32 c0_;
int position_;
// Property handles are stored here inside ParseJsonObject.
ZoneVector<Handle<Object>> properties_;
};
} // namespace internal