From 09b1574baa39dbc98c0d384895b131dfd3b23ee5 Mon Sep 17 00:00:00 2001 From: "verwaest@chromium.org" Date: Wed, 28 Nov 2012 08:41:45 +0000 Subject: [PATCH] Make ElementsAccessors more tolerant of varying backing store types This avoids bogus calls to Fixed*Array::cast() when FastElements-backed objects are empty (and thus backed by empty_fixed_array). Review URL: https://chromiumcodereview.appspot.com/11299190 Patch from Adam Klein . git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13071 ce2b1a6d-e550-0410-aec6-3dcde31c8c00 --- src/elements.cc | 29 +++++++++-------- .../regress/regress-observe-empty-double-array.js | 37 ++++++++++++++++++++++ 2 files changed, 53 insertions(+), 13 deletions(-) create mode 100644 test/mjsunit/regress/regress-observe-empty-double-array.js diff --git a/src/elements.cc b/src/elements.cc index 9ff77f7..ae5c7de 100644 --- a/src/elements.cc +++ b/src/elements.cc @@ -528,7 +528,7 @@ class ElementsAccessorBase : public ElementsAccessor { static bool HasElementImpl(Object* receiver, JSObject* holder, uint32_t key, - BackingStore* backing_store) { + FixedArrayBase* backing_store) { return ElementsAccessorSubclass::GetAttributesImpl( receiver, holder, key, backing_store) != ABSENT; } @@ -573,18 +573,18 @@ class ElementsAccessorBase : public ElementsAccessor { backing_store = holder->elements(); } return ElementsAccessorSubclass::GetAttributesImpl( - receiver, holder, key, BackingStore::cast(backing_store)); + receiver, holder, key, backing_store); } MUST_USE_RESULT static PropertyAttributes GetAttributesImpl( Object* receiver, JSObject* obj, uint32_t key, - BackingStore* backing_store) { + FixedArrayBase* backing_store) { if (key >= ElementsAccessorSubclass::GetCapacityImpl(backing_store)) { return ABSENT; } - return backing_store->is_the_hole(key) ? ABSENT : NONE; + return BackingStore::cast(backing_store)->is_the_hole(key) ? ABSENT : NONE; } MUST_USE_RESULT virtual PropertyType GetType( @@ -784,13 +784,12 @@ class ElementsAccessorBase : public ElementsAccessor { } protected: - static uint32_t GetCapacityImpl(BackingStore* backing_store) { + static uint32_t GetCapacityImpl(FixedArrayBase* backing_store) { return backing_store->length(); } virtual uint32_t GetCapacity(FixedArrayBase* backing_store) { - return ElementsAccessorSubclass::GetCapacityImpl( - BackingStore::cast(backing_store)); + return ElementsAccessorSubclass::GetCapacityImpl(backing_store); } static uint32_t GetKeyForIndexImpl(BackingStore* backing_store, @@ -1210,7 +1209,7 @@ class ExternalElementsAccessor Object* receiver, JSObject* obj, uint32_t key, - BackingStore* backing_store) { + FixedArrayBase* backing_store) { return key < ExternalElementsAccessorSubclass::GetCapacityImpl(backing_store) ? NONE : ABSENT; @@ -1519,10 +1518,12 @@ class DictionaryElementsAccessor Object* receiver, JSObject* obj, uint32_t key, - SeededNumberDictionary* backing_store) { - int entry = backing_store->FindEntry(key); + FixedArrayBase* backing_store) { + SeededNumberDictionary* dictionary = + SeededNumberDictionary::cast(backing_store); + int entry = dictionary->FindEntry(key); if (entry != SeededNumberDictionary::kNotFound) { - return backing_store->DetailsAt(entry).attributes(); + return dictionary->DetailsAt(entry).attributes(); } return ABSENT; } @@ -1616,7 +1617,8 @@ class NonStrictArgumentsElementsAccessor : public ElementsAccessorBase< Object* receiver, JSObject* obj, uint32_t key, - FixedArray* parameter_map) { + FixedArrayBase* backing_store) { + FixedArray* parameter_map = FixedArray::cast(backing_store); Object* probe = GetParameterMapArg(obj, parameter_map, key); if (!probe->IsTheHole()) { return NONE; @@ -1708,7 +1710,8 @@ class NonStrictArgumentsElementsAccessor : public ElementsAccessorBase< to_start, copy_size, arguments); } - static uint32_t GetCapacityImpl(FixedArray* parameter_map) { + static uint32_t GetCapacityImpl(FixedArrayBase* backing_store) { + FixedArray* parameter_map = FixedArray::cast(backing_store); FixedArrayBase* arguments = FixedArrayBase::cast(parameter_map->get(1)); return Max(static_cast(parameter_map->length() - 2), ForArray(arguments)->GetCapacity(arguments)); diff --git a/test/mjsunit/regress/regress-observe-empty-double-array.js b/test/mjsunit/regress/regress-observe-empty-double-array.js new file mode 100644 index 0000000..aea9c73 --- /dev/null +++ b/test/mjsunit/regress/regress-observe-empty-double-array.js @@ -0,0 +1,37 @@ +// 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: --harmony-observation --allow-natives-syntax +// +// Test passes if it does not crash. + +arr = [1.1]; +Object.observe(arr, function(){}); +arr.length = 0; +assertTrue(%HasFastDoubleElements(arr)); +// Should not crash +arr.push(1.1); -- 2.7.4