runtime/IntendedStructureChain.cpp

   1 /*
   2  * Copyright (C) 2013, 2014 Apple Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "config.h"
  27 #include "IntendedStructureChain.h"
  28
  29 #include "CodeBlock.h"
  30 #include "JSCInlines.h"
  31 #include "StructureChain.h"
  32 #include <wtf/CommaPrinter.h>
  33
  34 namespace JSC {
  35
  36 IntendedStructureChain::IntendedStructureChain(JSGlobalObject* globalObject, Structure* head)
  37     : m_globalObject(globalObject)
  38     , m_head(head)
  39 {
  40     JSValue prototype = head->prototypeForLookup(globalObject);
  41     if (prototype.isNull())
  42         return;
  43     for (Structure* current = asObject(prototype)->structure(); current; current = current->storedPrototypeStructure())
  44         m_vector.append(current);
  45 }
  46
  47 IntendedStructureChain::IntendedStructureChain(CodeBlock* codeBlock, Structure* head, Structure* prototypeStructure)
  48     : m_globalObject(codeBlock->globalObject())
  49     , m_head(head)
  50 {
  51     m_vector.append(prototypeStructure);
  52 }
  53
  54 IntendedStructureChain::IntendedStructureChain(CodeBlock* codeBlock, Structure* head, StructureChain* chain)
  55     : m_globalObject(codeBlock->globalObject())
  56     , m_head(head)
  57 {
  58     for (unsigned i = 0; chain->head()[i]; ++i)
  59         m_vector.append(chain->head()[i].get());
  60 }
  61
  62 IntendedStructureChain::IntendedStructureChain(CodeBlock* codeBlock, Structure* head, StructureChain* chain, unsigned count)
  63     : m_globalObject(codeBlock->globalObject())
  64     , m_head(head)
  65 {
  66     for (unsigned i = 0; i < count; ++i)
  67         m_vector.append(chain->head()[i].get());
  68 }
  69
  70 IntendedStructureChain::~IntendedStructureChain()
  71 {
  72 }
  73
  74 bool IntendedStructureChain::isStillValid() const
  75 {
  76     JSValue currentPrototype = m_head->prototypeForLookup(m_globalObject);
  77     for (unsigned i = 0; i < m_vector.size(); ++i) {
  78         if (asObject(currentPrototype)->structure() != m_vector[i])
  79             return false;
  80         currentPrototype = m_vector[i]->storedPrototype();
  81     }
  82     return true;
  83 }
  84
  85 bool IntendedStructureChain::matches(StructureChain* chain) const
  86 {
  87     for (unsigned i = 0; i < m_vector.size(); ++i) {
  88         if (m_vector[i] != chain->head()[i].get())
  89             return false;
  90     }
  91     if (chain->head()[m_vector.size()])
  92         return false;
  93     return true;
  94 }
  95
  96 StructureChain* IntendedStructureChain::chain(VM& vm) const
  97 {
  98     ASSERT(isStillValid());
  99     StructureChain* result = StructureChain::create(vm, m_head);
 100     ASSERT(matches(result));
 101     return result;
 102 }
 103
 104 bool IntendedStructureChain::mayInterceptStoreTo(VM& vm, StringImpl* uid)
 105 {
 106     for (unsigned i = 0; i < m_vector.size(); ++i) {
 107         unsigned attributes;
 108         JSCell* specificValue;
 109         PropertyOffset offset = m_vector[i]->getConcurrently(vm, uid, attributes, specificValue);
 110         if (!isValidOffset(offset))
 111             continue;
 112         if (attributes & (ReadOnly | Accessor))
 113             return true;
 114         return false;
 115     }
 116     return false;
 117 }
 118
 119 bool IntendedStructureChain::isNormalized()
 120 {
 121     if (m_head->isProxy())
 122         return false;
 123     for (unsigned i = 0; i < m_vector.size(); ++i) {
 124         Structure* structure = m_vector[i];
 125         if (structure->isProxy())
 126             return false;
 127         if (structure->isDictionary())
 128             return false;
 129     }
 130     return true;
 131 }
 132
 133 JSObject* IntendedStructureChain::terminalPrototype() const
 134 {
 135     ASSERT(!m_vector.isEmpty());
 136     if (m_vector.size() == 1)
 137         return asObject(m_head->prototypeForLookup(m_globalObject));
 138     return asObject(m_vector[m_vector.size() - 2]->storedPrototype());
 139 }
 140
 141 void IntendedStructureChain::visitChildren(SlotVisitor& visitor)
 142 {
 143     visitor.appendUnbarrieredPointer(&m_globalObject);
 144     visitor.appendUnbarrieredPointer(&m_head);
 145     for (unsigned i = m_vector.size(); i--;)
 146         visitor.appendUnbarrieredPointer(&m_vector[i]);
 147 }
 148
 149 void IntendedStructureChain::dump(PrintStream& out) const
 150 {
 151     dumpInContext(out, 0);
 152 }
 153
 154 void IntendedStructureChain::dumpInContext(PrintStream& out, DumpContext* context) const
 155 {
 156     out.print(
 157         "(global = ", RawPointer(m_globalObject), ", head = ",
 158         pointerDumpInContext(m_head, context), ", vector = [");
 159     CommaPrinter comma;
 160     for (unsigned i = 0; i < m_vector.size(); ++i)
 161         out.print(comma, pointerDumpInContext(m_vector[i], context));
 162     out.print("])");
 163 }
 164
 165 } // namespace JSC
 166