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[esnext] only load .next() once for JSAsyncFromSyncIterator

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A version of the spec change from
https://github.com/tc39/ecma262/pull/988, but applied to the
Async-from-Sync iterator type.

This change does not modify generated bytecode (but maybe it should to
take advantage of load IC feedback for loading "next"). Doing this grows
bytecode by quite a bit, since it's necessary to throw-if-not-an-object
before loading "next" (which currently gets to live in a code stub
instead).

BUG=v8:5855

Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: I0d2affef664d1069b24c54a553d62e17b49e5a16
Reviewed-on: https://chromium-review.googlesource.com/723136
Commit-Queue: Caitlin Potter <caitp@igalia.com>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51078}
This commit is contained in:
Caitlin Potter 2018-01-11 15:58:57 -05:00 committed by Commit Bot
parent 9bffe96121
commit 6b1586e32b
9 changed files with 49 additions and 22 deletions
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30
src/builtins/builtins-async-iterator-gen.cc
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@ -28,13 +28,29 @@ class AsyncFromSyncBuiltinsAssembler : public AsyncBuiltinsAssembler {
typedef std::function<void(Node* const context, Node* const promise,
Label* if_exception)>
UndefinedMethodHandler;
typedef std::function<Node*(Node*)> SyncIteratorNodeGenerator;
void Generate_AsyncFromSyncIteratorMethod(
Node* const context, Node* const iterator, Node* const sent_value,
Handle<Name> method_name, UndefinedMethodHandler&& if_method_undefined,
const SyncIteratorNodeGenerator& get_method,
const UndefinedMethodHandler& if_method_undefined,
const char* operation_name,
Label::Type reject_label_type = Label::kDeferred,
Node* const initial_exception_value = nullptr);
void Generate_AsyncFromSyncIteratorMethod(
Node* const context, Node* const iterator, Node* const sent_value,
Handle<String> name, const UndefinedMethodHandler& if_method_undefined,
const char* operation_name,
Label::Type reject_label_type = Label::kDeferred,
Node* const initial_exception_value = nullptr) {
auto get_method = [=](Node* const sync_iterator) {
return GetProperty(context, sync_iterator, name);
};
return Generate_AsyncFromSyncIteratorMethod(
context, iterator, sent_value, get_method, if_method_undefined,
operation_name, reject_label_type, initial_exception_value);
}
// Load "value" and "done" from an iterator result object. If an exception
// is thrown at any point, jumps to te `if_exception` label with exception
// stored in `var_exception`.
@ -79,7 +95,8 @@ void AsyncFromSyncBuiltinsAssembler::ThrowIfNotAsyncFromSyncIterator(
void AsyncFromSyncBuiltinsAssembler::Generate_AsyncFromSyncIteratorMethod(
Node* const context, Node* const iterator, Node* const sent_value,
Handle<Name> method_name, UndefinedMethodHandler&& if_method_undefined,
const SyncIteratorNodeGenerator& get_method,
const UndefinedMethodHandler& if_method_undefined,
const char* operation_name, Label::Type reject_label_type,
Node* const initial_exception_value) {
Node* const native_context = LoadNativeContext(context);
@ -96,7 +113,7 @@ void AsyncFromSyncBuiltinsAssembler::Generate_AsyncFromSyncIteratorMethod(
Node* const sync_iterator =
LoadObjectField(iterator, JSAsyncFromSyncIterator::kSyncIteratorOffset);
Node* const method = GetProperty(context, sync_iterator, method_name);
Node* const method = get_method(sync_iterator);
if (if_method_undefined) {
Label if_isnotundefined(this);
@ -220,9 +237,12 @@ TF_BUILTIN(AsyncFromSyncIteratorPrototypeNext, AsyncFromSyncBuiltinsAssembler) {
Node* const value = Parameter(Descriptor::kValue);
Node* const context = Parameter(Descriptor::kContext);
auto get_method = [=](Node* const unused) {
return LoadObjectField(iterator, JSAsyncFromSyncIterator::kNextOffset);
};
Generate_AsyncFromSyncIteratorMethod(
context, iterator, value, factory()->next_string(),
UndefinedMethodHandler(), "[Async-from-Sync Iterator].prototype.next");
context, iterator, value, get_method, UndefinedMethodHandler(),
"[Async-from-Sync Iterator].prototype.next");
}
// https://tc39.github.io/proposal-async-iteration/

3
src/factory.cc
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@ -2097,12 +2097,13 @@ Handle<JSIteratorResult> Factory::NewJSIteratorResult(Handle<Object> value,
}
Handle<JSAsyncFromSyncIterator> Factory::NewJSAsyncFromSyncIterator(
Handle<JSReceiver> sync_iterator) {
Handle<JSReceiver> sync_iterator, Handle<Object> next) {
Handle<Map> map(isolate()->native_context()->async_from_sync_iterator_map());
Handle<JSAsyncFromSyncIterator> iterator =
Handle<JSAsyncFromSyncIterator>::cast(NewJSObjectFromMap(map));
iterator->set_sync_iterator(*sync_iterator);
iterator->set_next(*next);
return iterator;
}

2
src/factory.h
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@ -600,7 +600,7 @@ class V8_EXPORT_PRIVATE Factory final {
Handle<JSIteratorResult> NewJSIteratorResult(Handle<Object> value, bool done);
Handle<JSAsyncFromSyncIterator> NewJSAsyncFromSyncIterator(
Handle<JSReceiver> sync_iterator);
Handle<JSReceiver> sync_iterator, Handle<Object> next);
Handle<JSMap> NewJSMap();
Handle<JSSet> NewJSSet();

7
src/interpreter/interpreter-intrinsics-generator.cc
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@ -7,6 +7,7 @@
#include "src/allocation.h"
#include "src/builtins/builtins.h"
#include "src/code-factory.h"
#include "src/factory-inl.h"
#include "src/frames.h"
#include "src/interpreter/bytecodes.h"
#include "src/interpreter/interpreter-assembler.h"
@ -52,6 +53,7 @@ class IntrinsicsGenerator {
Isolate* isolate() { return isolate_; }
Zone* zone() { return zone_; }
Factory* factory() { return isolate()->factory(); }
Isolate* isolate_;
Zone* zone_;
@ -368,6 +370,9 @@ Node* IntrinsicsGenerator::CreateAsyncFromSyncIterator(
__ GotoIf(__ TaggedIsSmi(sync_iterator), &not_receiver);
__ GotoIfNot(__ IsJSReceiver(sync_iterator), &not_receiver);
Node* const next =
__ GetProperty(context, sync_iterator, factory()->next_string());
Node* const native_context = __ LoadNativeContext(context);
Node* const map = __ LoadContextElement(
native_context, Context::ASYNC_FROM_SYNC_ITERATOR_MAP_INDEX);
@ -375,6 +380,8 @@ Node* IntrinsicsGenerator::CreateAsyncFromSyncIterator(
__ StoreObjectFieldNoWriteBarrier(
iterator, JSAsyncFromSyncIterator::kSyncIteratorOffset, sync_iterator);
__ StoreObjectFieldNoWriteBarrier(iterator,
JSAsyncFromSyncIterator::kNextOffset, next);
return_value.Bind(iterator);
__ Goto(&done);

1
src/objects-inl.h
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@ -3520,6 +3520,7 @@ ACCESSORS(JSIteratorResult, done, Object, kDoneOffset)
ACCESSORS(JSAsyncFromSyncIterator, sync_iterator, JSReceiver,
kSyncIteratorOffset)
ACCESSORS(JSAsyncFromSyncIterator, next, Object, kNextOffset)
ACCESSORS(JSStringIterator, string, String, kStringOffset)
SMI_ACCESSORS(JSStringIterator, index, kNextIndexOffset)

7
src/objects.h
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@ -4602,9 +4602,14 @@ class JSAsyncFromSyncIterator : public JSObject {
// (proposal-async-iteration/#table-async-from-sync-iterator-internal-slots)
DECL_ACCESSORS(sync_iterator, JSReceiver)
// The "next" method is loaded during GetIterator, and is not reloaded for
// subsequent "next" invocations.
DECL_ACCESSORS(next, Object)
// Offsets of object fields.
static const int kSyncIteratorOffset = JSObject::kHeaderSize;
static const int kSize = kSyncIteratorOffset + kPointerSize;
static const int kNextOffset = kSyncIteratorOffset + kPointerSize;
static const int kSize = kNextOffset + kPointerSize;
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(JSAsyncFromSyncIterator);

7
src/runtime/runtime-internal.cc
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@ -634,8 +634,13 @@ RUNTIME_FUNCTION(Runtime_CreateAsyncFromSyncIterator) {
isolate, NewTypeError(MessageTemplate::kSymbolIteratorInvalid));
}
Handle<Object> next;
ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
isolate, next,
Object::GetProperty(sync_iterator, isolate->factory()->next_string()));
return *isolate->factory()->NewJSAsyncFromSyncIterator(
Handle<JSReceiver>::cast(sync_iterator));
Handle<JSReceiver>::cast(sync_iterator), next);
}
RUNTIME_FUNCTION(Runtime_GetTemplateObject) {

4
test/mjsunit/harmony/async-from-sync-iterator.js
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@ -717,8 +717,8 @@ if (testFailed) {
next_: 0,
get next() {
log.push("get syncIterable.next");
let i = this.next_++;
return (...args) => {
let i = this.next_++;
log.push("call syncIterable.next(" + args.join(", ") + ")");
return results[i];
}
@ -748,14 +748,12 @@ if (testFailed) {
"get nextValue#1.then",
"call nextValue#1.then",
"got value value1",
"get syncIterable.next",
"call syncIterable.next()",
"get iterResult #2.done",
"get iterResult #2.value",
"get nextValue#2.then",
"call nextValue#2.then",
"got value value2",
"get syncIterable.next",
"call syncIterable.next()",
"get iterResult #3.done",
"get iterResult #3.value",

10
test/test262/test262.status
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@ -419,16 +419,6 @@
'built-ins/Proxy/ownKeys/return-duplicate-entries-throws': [FAIL],
'built-ins/Proxy/ownKeys/return-duplicate-symbol-entries-throws': [FAIL],
# https://bugs.chromium.org/p/v8/issues/detail?id=6861
'language/expressions/object/method-definition/async-gen-yield-star-sync-next': [FAIL],
'language/expressions/class/async-gen-method-static-yield-star-sync-next': [FAIL],
'language/expressions/async-generator/yield-star-sync-next': [FAIL],
'language/statements/class/async-gen-method-static-yield-star-sync-next': [FAIL],
'language/expressions/async-generator/named-yield-star-sync-next': [FAIL],
'language/expressions/class/async-gen-method-yield-star-sync-next': [FAIL],
'language/statements/class/async-gen-method-yield-star-sync-next': [FAIL],
'language/statements/async-generator/yield-star-sync-next': [FAIL],
# https://bugs.chromium.org/p/v8/issues/detail?id=6791
'built-ins/BigInt/prototype/Symbol.toStringTag': [SKIP],
'built-ins/DataView/prototype/getBigInt64/*': [SKIP],