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[array] Move fall-back for Array.p.shift to C++

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This CL replaces the JavaScript fall-back for Array.p.shift with a
baseline C++ implementation.

R=jgruber@chromium.org

Bug: v8:7624
Change-Id: Ib55e04e18e4e69089fc541636d3cad7fcb4c7245
Reviewed-on: https://chromium-review.googlesource.com/1186327
Commit-Queue: Simon Zünd <szuend@google.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55576}
This commit is contained in:
Simon Zünd 2018-08-29 09:04:00 +02:00 committed by Commit Bot
parent 274242fe30
commit a45a20e446
4 changed files with 132 additions and 47 deletions
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127
src/builtins/builtins-array.cc
View File

@ -189,6 +189,24 @@ V8_WARN_UNUSED_RESULT Maybe<double> GetLengthProperty(
return Just(raw_length_number->Number());
}
// Set "length" property, has "fast-path" for JSArrays.
// Returns Nothing if something went wrong.
V8_WARN_UNUSED_RESULT MaybeHandle<Object> SetLengthProperty(
Isolate* isolate, Handle<JSReceiver> receiver, double length) {
if (receiver->IsJSArray()) {
Handle<JSArray> array = Handle<JSArray>::cast(receiver);
if (!JSArray::HasReadOnlyLength(array)) {
DCHECK_LE(length, kMaxUInt32);
JSArray::SetLength(array, static_cast<uint32_t>(length));
return receiver;
}
}
return Object::SetProperty(
isolate, receiver, isolate->factory()->length_string(),
isolate->factory()->NewNumber(length), LanguageMode::kStrict);
}
V8_WARN_UNUSED_RESULT Object* GenericArrayFill(Isolate* isolate,
Handle<JSReceiver> receiver,
Handle<Object> value,
@ -485,27 +503,116 @@ BUILTIN(ArrayPop) {
return *result;
}
BUILTIN(ArrayShift) {
HandleScope scope(isolate);
Heap* heap = isolate->heap();
Handle<Object> receiver = args.receiver();
namespace {
// Returns true, iff we can use ElementsAccessor for shifting.
V8_WARN_UNUSED_RESULT bool CanUseFastArrayShift(Isolate* isolate,
Handle<JSReceiver> receiver) {
if (!EnsureJSArrayWithWritableFastElements(isolate, receiver, nullptr, 0,
0) ||
!IsJSArrayFastElementMovingAllowed(isolate, JSArray::cast(*receiver))) {
return CallJsIntrinsic(isolate, isolate->array_shift(), args);
return false;
}
Handle<JSArray> array = Handle<JSArray>::cast(receiver);
return !JSArray::HasReadOnlyLength(array);
}
int len = Smi::ToInt(array->length());
if (len == 0) return ReadOnlyRoots(heap).undefined_value();
V8_WARN_UNUSED_RESULT Object* GenericArrayShift(Isolate* isolate,
Handle<JSReceiver> receiver,
double length) {
// 4. Let first be ? Get(O, "0").
Handle<Object> first;
ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, first,
Object::GetElement(isolate, receiver, 0));
if (JSArray::HasReadOnlyLength(array)) {
return CallJsIntrinsic(isolate, isolate->array_shift(), args);
// 5. Let k be 1.
double k = 1;
// 6. Repeat, while k < len.
while (k < length) {
// a. Let from be ! ToString(k).
Handle<String> from =
isolate->factory()->NumberToString(isolate->factory()->NewNumber(k));
// b. Let to be ! ToString(k-1).
Handle<String> to = isolate->factory()->NumberToString(
isolate->factory()->NewNumber(k - 1));
// c. Let fromPresent be ? HasProperty(O, from).
bool from_present;
MAYBE_ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
isolate, from_present, JSReceiver::HasProperty(receiver, from));
// d. If fromPresent is true, then.
if (from_present) {
// i. Let fromVal be ? Get(O, from).
Handle<Object> from_val;
ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
isolate, from_val,
Object::GetPropertyOrElement(isolate, receiver, from));
// ii. Perform ? Set(O, to, fromVal, true).
RETURN_FAILURE_ON_EXCEPTION(
isolate, Object::SetPropertyOrElement(isolate, receiver, to, from_val,
LanguageMode::kStrict));
} else { // e. Else fromPresent is false,
// i. Perform ? DeletePropertyOrThrow(O, to).
MAYBE_RETURN(JSReceiver::DeletePropertyOrElement(receiver, to,
LanguageMode::kStrict),
ReadOnlyRoots(isolate).exception());
}
// f. Increase k by 1.
++k;
}
Handle<Object> first = array->GetElementsAccessor()->Shift(array);
// 7. Perform ? DeletePropertyOrThrow(O, ! ToString(len-1)).
Handle<String> new_length = isolate->factory()->NumberToString(
isolate->factory()->NewNumber(length - 1));
MAYBE_RETURN(JSReceiver::DeletePropertyOrElement(receiver, new_length,
LanguageMode::kStrict),
ReadOnlyRoots(isolate).exception());
// 8. Perform ? Set(O, "length", len-1, true).
RETURN_FAILURE_ON_EXCEPTION(isolate,
SetLengthProperty(isolate, receiver, length - 1));
// 9. Return first.
return *first;
}
} // namespace
BUILTIN(ArrayShift) {
HandleScope scope(isolate);
// 1. Let O be ? ToObject(this value).
Handle<JSReceiver> receiver;
ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
isolate, receiver, Object::ToObject(isolate, args.receiver()));
// 2. Let len be ? ToLength(? Get(O, "length")).
double length;
MAYBE_ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
isolate, length, GetLengthProperty(isolate, receiver));
// 3. If len is zero, then.
if (length == 0) {
// a. Perform ? Set(O, "length", 0, true).
RETURN_FAILURE_ON_EXCEPTION(isolate,
SetLengthProperty(isolate, receiver, length));
// b. Return undefined.
return ReadOnlyRoots(isolate).undefined_value();
}
if (CanUseFastArrayShift(isolate, receiver)) {
Handle<JSArray> array = Handle<JSArray>::cast(receiver);
return *array->GetElementsAccessor()->Shift(array);
}
return GenericArrayShift(isolate, receiver, length);
}
BUILTIN(ArrayUnshift) {
HandleScope scope(isolate);

1
src/contexts.h
View File

@ -72,7 +72,6 @@ enum ContextLookupFlags {
V(ASYNC_GENERATOR_AWAIT_UNCAUGHT, JSFunction, async_generator_await_uncaught)
#define NATIVE_CONTEXT_IMPORTED_FIELDS(V) \
V(ARRAY_SHIFT_INDEX, JSFunction, array_shift) \
V(ARRAY_SPLICE_INDEX, JSFunction, array_splice) \
V(ARRAY_UNSHIFT_INDEX, JSFunction, array_unshift) \
V(ARRAY_ENTRIES_ITERATOR_INDEX, JSFunction, array_entries_iterator) \

24
src/js/array.js
View File

@ -408,29 +408,6 @@ DEFINE_METHOD(
);
function ArrayShiftFallback() {
var array = TO_OBJECT(this);
var len = TO_LENGTH(array.length);
if (len === 0) {
array.length = 0;
return;
}
var first = array[0];
if (UseSparseVariant(array, len, IS_ARRAY(array), len)) {
SparseMove(array, 0, 1, len, 0);
} else {
SimpleMove(array, 0, 1, len, 0);
}
array.length = len - 1;
return first;
}
function ArrayUnshiftFallback(arg1) { // length == 1
var array = TO_OBJECT(this);
var len = TO_LENGTH(array.length);
@ -778,7 +755,6 @@ utils.Export(function(to) {
"array_keys_iterator", ArrayKeys,
"array_values_iterator", ArrayValues,
// Fallback implementations of Array builtins.
"array_shift", ArrayShiftFallback,
"array_splice", ArraySpliceFallback,
"array_unshift", ArrayUnshiftFallback,
]);

27
test/mjsunit/array-functions-prototype-misc.js
View File

@ -252,19 +252,22 @@ for (var use_real_arrays = 0; use_real_arrays <= 1; use_real_arrays++) {
assertEquals("bar", a[2]);
// Shift.
var baz = shift_function(a);
assertEquals("baz", baz);
assertEquals("boo", a[0]);
assertEquals(pos + 3, a.length);
assertEquals("foo", a[pos + 2]);
// Slice.
var bar = slice_function(a, 1, 0); // don't throw an exception please.
bar = slice_function(a, 1, 2);
assertEquals("bar", bar[0]);
assertEquals(1, bar.length);
assertEquals("bar", a[1]);
// Skip VERYLARGE arrays, as we removed sparse support for shift.
// Slice is also skipped, since it relies on the "shift" test to be run.
if (pos < VERYLARGE) {
var baz = shift_function(a);
assertEquals("baz", baz);
assertEquals("boo", a[0]);
assertEquals(pos + 3, a.length);
assertEquals("foo", a[pos + 2]);
// Slice.
var bar = slice_function(a, 1, 0); // don't throw an exception please.
bar = slice_function(a, 1, 2);
assertEquals("bar", bar[0]);
assertEquals(1, bar.length);
assertEquals("bar", a[1]);
}
}
}