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Introduce builtin for Array.slice function.

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Review URL: http://codereview.chromium.org/604059

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3871 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
antonm@chromium.org 2010-02-16 12:14:23 +00:00
parent 899bef8226
commit ea1b4f0eb1
6 changed files with 271 additions and 2 deletions
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2
src/bootstrapper.cc
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@ -1495,6 +1495,8 @@ void Genesis::BuildSpecialFunctionTable() {
Handle<Code>(Builtins::builtin(Builtins::ArrayShift)));
AddSpecialFunction(special_prototype, "unshift",
Handle<Code>(Builtins::builtin(Builtins::ArrayUnshift)));
AddSpecialFunction(special_prototype, "slice",
Handle<Code>(Builtins::builtin(Builtins::ArraySlice)));
}

104
src/builtins.cc
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@ -419,6 +419,110 @@ BUILTIN(ArrayUnshift) {
}
static Object* SlowArraySlice(Handle<Object> receiver,
Object** arg0,
Object** arg1 = NULL) {
HandleScope handleScope;
Handle<Object> slow_slice =
GetProperty(Handle<JSObject>(Top::global_context()->builtins()),
"ArraySlice");
ASSERT(slow_slice->IsJSFunction());
Handle<JSFunction> function(Handle<JSFunction>::cast(slow_slice));
Object** args[] = { arg0, arg1 };
bool pending_exception = false;
Handle<Object> result = Execution::Call(function,
receiver,
arg1 == NULL ? 1 : 2,
args,
&pending_exception);
if (pending_exception) return Failure::Exception();
return *result;
}
BUILTIN(ArraySlice) {
JSArray* array = JSArray::cast(*args.receiver());
ASSERT(array->HasFastElements());
int len = Smi::cast(array->length())->value();
int n_arguments = args.length() - 1;
// Note carefully choosen defaults---if argument is missing,
// it's undefined which gets converted to 0 for relativeStart
// and to len for relativeEnd.
int relativeStart = 0;
int relativeEnd = len;
if (n_arguments > 0) {
Object* arg1 = args[1];
if (arg1->IsSmi()) {
relativeStart = Smi::cast(arg1)->value();
} else if (!arg1->IsUndefined()) {
if (n_arguments > 1) {
return SlowArraySlice(args.receiver(), &args[1], &args[2]);
} else {
return SlowArraySlice(args.receiver(), &args[1]);
}
}
if (n_arguments > 1) {
Object* arg2 = args[2];
if (arg2->IsSmi()) {
relativeEnd = Smi::cast(arg2)->value();
} else if (!arg2->IsUndefined()) {
return SlowArraySlice(args.receiver(), &args[1], &args[2]);
}
}
}
// ECMAScript 232, 3rd Edition, Section 15.4.4.10, step 6.
int k = (relativeStart < 0) ? Max(len + relativeStart, 0)
: Min(relativeStart, len);
// ECMAScript 232, 3rd Edition, Section 15.4.4.10, step 8.
int final = (relativeEnd < 0) ? Max(len + relativeEnd, 0)
: Min(relativeEnd, len);
// Calculate the length of result array.
int result_len = final - k;
if (result_len < 0) {
result_len = 0;
}
JSFunction* array_function =
Top::context()->global_context()->array_function();
Object* result = Heap::AllocateJSObject(array_function);
if (result->IsFailure()) return result;
JSArray* result_array = JSArray::cast(result);
result = Heap::AllocateFixedArrayWithHoles(result_len);
if (result->IsFailure()) return result;
FixedArray* result_elms = FixedArray::cast(result);
FixedArray* elms = FixedArray::cast(array->elements());
// Fetch the prototype.
JSObject* prototype = JSObject::cast(array_function->prototype());
AssertNoAllocation no_gc;
WriteBarrierMode mode = result_elms->GetWriteBarrierMode(no_gc);
// Fill newly created array.
for (int i = 0; i < result_len; i++) {
result_elms->set(i,
GetElementToMove(k + i, elms, prototype),
mode);
}
// Set elements.
result_array->set_elements(result_elms);
// Set the length.
result_array->set_length(Smi::FromInt(result_len));
return result_array;
}
// -----------------------------------------------------------------------------
//

1
src/builtins.h
View File

@ -50,6 +50,7 @@ enum BuiltinExtraArguments {
V(ArrayPop, NO_EXTRA_ARGUMENTS) \
V(ArrayShift, NO_EXTRA_ARGUMENTS) \
V(ArrayUnshift, NO_EXTRA_ARGUMENTS) \
V(ArraySlice, NO_EXTRA_ARGUMENTS) \
\
V(HandleApiCall, NEEDS_CALLED_FUNCTION) \
V(FastHandleApiCall, NO_EXTRA_ARGUMENTS) \

2
src/ic.cc
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@ -455,7 +455,7 @@ Object* CallIC::LoadFunction(State state,
if (result->IsJSFunction()) {
// Check if there is an optimized (builtin) version of the function.
// Ignored this will degrade performance for Array.prototype.{push,pop}.
// Ignored this will degrade performance for some Array functions.
// Please note we only return the optimized function iff
// the JSObject has FastElements.
if (object->IsJSObject() && JSObject::cast(*object)->HasFastElements()) {

162
test/mjsunit/array-slice.js Normal file
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@ -0,0 +1,162 @@
// Copyright 2010 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Check that slicing array of holes keeps it as array of holes
(function() {
var array = new Array(10);
for (var i = 0; i < 7; i++) {
var sliced = array.slice();
assertEquals(array.length, sliced.length);
assertFalse(0 in sliced);
}
})();
// Check various forms of arguments omission.
(function() {
var array = new Array(7);
for (var i = 0; i < 7; i++) {
assertEquals(array, array.slice());
assertEquals(array, array.slice(0));
assertEquals(array, array.slice(undefined));
assertEquals(array, array.slice("foobar"));
assertEquals(array, array.slice(undefined, undefined));
}
})();
// Check variants of negatives and positive indices.
(function() {
var array = new Array(7);
for (var i = 0; i < 7; i++) {
assertEquals(7, array.slice(-100).length);
assertEquals(3, array.slice(-3).length);
assertEquals(3, array.slice(4).length);
assertEquals(1, array.slice(6).length);
assertEquals(0, array.slice(7).length);
assertEquals(0, array.slice(8).length);
assertEquals(0, array.slice(100).length);
assertEquals(0, array.slice(0, -100).length);
assertEquals(4, array.slice(0, -3).length);
assertEquals(4, array.slice(0, 4).length);
assertEquals(6, array.slice(0, 6).length);
assertEquals(7, array.slice(0, 7).length);
assertEquals(7, array.slice(0, 8).length);
assertEquals(7, array.slice(0, 100).length);
// Some exotic cases.
obj = { toString: function() { throw 'Exception'; } };
// More than 2 arguments:
assertEquals(7, array.slice(0, 7, obj, null, undefined).length);
// Custom conversion:
assertEquals(1, array.slice({valueOf: function() { return 1; }},
{toString: function() { return 2; }}).length);
// Throwing an exception in conversion:
try {
assertEquals(7, array.slice(0, obj).length);
throw 'Should have thrown';
} catch (e) {
assertEquals('Exception', e);
}
}
})();
// Nasty: modify the array in ToInteger.
(function() {
var array = [];
var expected = []
bad_guy = { valueOf: function() { array.push(array.length); return -1; } };
for (var i = 0; i < 13; i++) {
var sliced = array.slice(bad_guy);
expected.push(i);
assertEquals(expected, array);
// According to the spec (15.4.4.10), length is calculated before
// performing ToInteger on arguments.
if (i == 0) {
assertEquals([], sliced); // Length was 0, nothing to get.
} else {
// Actually out of array [0..i] we get [i - 1] as length is i.
assertEquals([i - 1], sliced);
}
}
})();
// Now check the case with array of holes and some elements on prototype.
(function() {
var len = 9;
var array = new Array(len);
var at3 = "@3";
var at7 = "@7";
for (var i = 0; i < 7; i++) {
Array.prototype[3] = at3;
Array.prototype[7] = at7;
assertEquals(len, array.length);
for (var i = 0; i < array.length; i++) {
assertEquals(array[i], Array.prototype[i]);
}
var sliced = array.slice();
assertEquals(len, sliced.length);
assertTrue(delete Array.prototype[3]);
assertTrue(delete Array.prototype[7]);
// Note that slice copies values from prototype into the array.
assertEquals(array[3], undefined);
assertFalse(array.hasOwnProperty(3));
assertEquals(sliced[3], at3);
assertTrue(sliced.hasOwnProperty(3));
assertEquals(array[7], undefined);
assertFalse(array.hasOwnProperty(7));
assertEquals(sliced[7], at7);
assertTrue(sliced.hasOwnProperty(7));
// ... but keeps the rest as holes:
Array.prototype[5] = "@5";
assertEquals(array[5], Array.prototype[5]);
assertFalse(array.hasOwnProperty(5));
assertEquals(sliced[5], Array.prototype[5]);
assertFalse(sliced.hasOwnProperty(5));
assertTrue(delete Array.prototype[5]);
}
})();