Reviewers: Jakob,
Description:
Remove over-zealous hole checking in Array.slice()
[email protected]
BUG=chromium:165637
TEST=regress-165637.js
Please review this at https://chromiumcodereview.appspot.com/11442054/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/builtins.cc
A test/mjsunit/regress/regress-165637.js
Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index
d62713db4cf3ec39882ac1e717318c9253476988..97fcaebff5875553bc19e1aa33cd54bf3a61beea
100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -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,
Index: test/mjsunit/regress/regress-165637.js
diff --git a/test/mjsunit/regress/regress-165637.js
b/test/mjsunit/regress/regress-165637.js
new file mode 100644
index
0000000000000000000000000000000000000000..97aad1579376411dae7509719683a90bdd27c1c4
--- /dev/null
+++ b/test/mjsunit/regress/regress-165637.js
@@ -0,0 +1,55 @@
+// Copyright 2009 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.
+
+// 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])
--
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