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Remove over-zealous hole checking in Array.slice()

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R=jkummerow@chromium.org
BUG=chromium:165637
TEST=regress-165637.js

Review URL: https://codereview.chromium.org/11442054

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13211 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
danno@chromium.org 2012-12-12 15:20:45 +00:00
parent 13a0b6bfa8
commit facad070e9
2 changed files with 74 additions and 17 deletions
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34
src/builtins.cc
View File

@ -858,23 +858,6 @@ BUILTIN(ArraySlice) {
}
JSObject* object = JSObject::cast(receiver);
ElementsKind kind = object->GetElementsKind();
if (IsHoleyElementsKind(kind)) {
bool packed = true;
ElementsAccessor* accessor = ElementsAccessor::ForKind(kind);
for (int i = 0; i < len; i++) {
if (!accessor->HasElement(object, object, i, elms)) {
packed = false;
break;
}
}
if (packed) {
kind = GetPackedElementsKind(kind);
} else if (!receiver->IsJSArray()) {
return CallJsBuiltin(isolate, "ArraySlice", args);
}
}
ASSERT(len >= 0);
int n_arguments = args.length() - 1;
@ -924,6 +907,23 @@ BUILTIN(ArraySlice) {
// Calculate the length of result array.
int result_len = Max(final - k, 0);
ElementsKind kind = object->GetElementsKind();
if (IsHoleyElementsKind(kind)) {
bool packed = true;
ElementsAccessor* accessor = ElementsAccessor::ForKind(kind);
for (int i = k; i < final; i++) {
if (!accessor->HasElement(object, object, i, elms)) {
packed = false;
break;
}
}
if (packed) {
kind = GetPackedElementsKind(kind);
} else if (!receiver->IsJSArray()) {
return CallJsBuiltin(isolate, "ArraySlice", args);
}
}
JSArray* result_array;
MaybeObject* maybe_array = heap->AllocateJSArrayAndStorage(kind,
result_len,

57
test/mjsunit/regress/regress-165637.js Normal file
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@ -0,0 +1,57 @@
// Copyright 2012 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.
// Flags: --allow-natives-syntax
// Should not take a very long time (n^2 algorithms are bad)
function do_slices() {
var data = new Array(1024 * 12); // 12kB
for (var i = 0; i < data.length; i++) {
data[i] = 255;
}
var start = Date.now();
for (i = 0; i < 20000; i++) {
data.slice(4, 1);
}
return Date.now() - start;
}
// Should never take more than 3 seconds (if the bug is fixed, the test takes
// considerably less time than 3 seconds).
assertTrue(do_slices() < (3 * 1000));
// Make sure that packed and unpacked array slices are still properly handled
var holey_array = [1, 2, 3, 4, 5,,,,,,];
assertFalse(%HasFastHoleyElements(holey_array.slice(6, 1)));
assertEquals(undefined, holey_array.slice(6, 7)[0])
assertFalse(%HasFastHoleyElements(holey_array.slice(2, 1)));
assertEquals(3, holey_array.slice(2, 3)[0])