bytecode/GetByIdStatus.cpp

   1 /*
   2  * Copyright (C) 2012 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 "GetByIdStatus.h"
  28
  29 #include "CodeBlock.h"
  30 #include "LowLevelInterpreter.h"
  31
  32 namespace JSC {
  33
  34 GetByIdStatus GetByIdStatus::computeFromLLInt(CodeBlock* profiledBlock, unsigned bytecodeIndex, Identifier& ident)
  35 {
  36     UNUSED_PARAM(profiledBlock);
  37     UNUSED_PARAM(bytecodeIndex);
  38     UNUSED_PARAM(ident);
  39 #if ENABLE(LLINT)
  40     Instruction* instruction = profiledBlock->instructions().begin() + bytecodeIndex;
  41
  42     if (instruction[0].u.opcode == llint_op_method_check)
  43         instruction++;
  44
  45     Structure* structure = instruction[4].u.structure.get();
  46     if (!structure)
  47         return GetByIdStatus(NoInformation, StructureSet(), notFound, false);
  48
  49     size_t offset = structure->get(*profiledBlock->globalData(), ident);
  50     if (offset == notFound)
  51         return GetByIdStatus(NoInformation, StructureSet(), notFound, false);
  52
  53     return GetByIdStatus(SimpleDirect, StructureSet(structure), offset, false);
  54 #else
  55     return GetByIdStatus(NoInformation, StructureSet(), notFound, false);
  56 #endif
  57 }
  58
  59 GetByIdStatus GetByIdStatus::computeFor(CodeBlock* profiledBlock, unsigned bytecodeIndex, Identifier& ident)
  60 {
  61     UNUSED_PARAM(profiledBlock);
  62     UNUSED_PARAM(bytecodeIndex);
  63     UNUSED_PARAM(ident);
  64 #if ENABLE(JIT) && ENABLE(VALUE_PROFILER)
  65     if (!profiledBlock->numberOfStructureStubInfos())
  66         return computeFromLLInt(profiledBlock, bytecodeIndex, ident);
  67
  68     // First check if it makes either calls, in which case we want to be super careful, or
  69     // if it's not set at all, in which case we punt.
  70     StructureStubInfo& stubInfo = profiledBlock->getStubInfo(bytecodeIndex);
  71     if (!stubInfo.seen)
  72         return computeFromLLInt(profiledBlock, bytecodeIndex, ident);
  73
  74     PolymorphicAccessStructureList* list;
  75     int listSize;
  76     switch (stubInfo.accessType) {
  77     case access_get_by_id_self_list:
  78         list = stubInfo.u.getByIdSelfList.structureList;
  79         listSize = stubInfo.u.getByIdSelfList.listSize;
  80         break;
  81     case access_get_by_id_proto_list:
  82         list = stubInfo.u.getByIdProtoList.structureList;
  83         listSize = stubInfo.u.getByIdProtoList.listSize;
  84         break;
  85     default:
  86         list = 0;
  87         listSize = 0;
  88         break;
  89     }
  90     for (int i = 0; i < listSize; ++i) {
  91         if (!list->list[i].isDirect)
  92             return GetByIdStatus(MakesCalls, StructureSet(), notFound, true);
  93     }
  94
  95     // Next check if it takes slow case, in which case we want to be kind of careful.
  96     if (profiledBlock->likelyToTakeSlowCase(bytecodeIndex))
  97         return GetByIdStatus(TakesSlowPath, StructureSet(), notFound, true);
  98
  99     // Finally figure out if we can derive an access strategy.
 100     GetByIdStatus result;
 101     result.m_wasSeenInJIT = true;
 102     switch (stubInfo.accessType) {
 103     case access_unset:
 104         return computeFromLLInt(profiledBlock, bytecodeIndex, ident);
 105
 106     case access_get_by_id_self: {
 107         Structure* structure = stubInfo.u.getByIdSelf.baseObjectStructure.get();
 108         result.m_offset = structure->get(*profiledBlock->globalData(), ident);
 109
 110         if (result.m_offset != notFound)
 111             result.m_structureSet.add(structure);
 112
 113         if (result.m_offset != notFound)
 114             ASSERT(result.m_structureSet.size());
 115         break;
 116     }
 117
 118     case access_get_by_id_self_list: {
 119         PolymorphicAccessStructureList* list = stubInfo.u.getByIdProtoList.structureList;
 120         unsigned size = stubInfo.u.getByIdProtoList.listSize;
 121         for (unsigned i = 0; i < size; ++i) {
 122             ASSERT(list->list[i].isDirect);
 123
 124             Structure* structure = list->list[i].base.get();
 125             if (result.m_structureSet.contains(structure))
 126                 continue;
 127
 128             size_t myOffset = structure->get(*profiledBlock->globalData(), ident);
 129
 130             if (myOffset == notFound) {
 131                 result.m_offset = notFound;
 132                 break;
 133             }
 134
 135             if (!i)
 136                 result.m_offset = myOffset;
 137             else if (result.m_offset != myOffset) {
 138                 result.m_offset = notFound;
 139                 break;
 140             }
 141
 142             result.m_structureSet.add(structure);
 143         }
 144
 145         if (result.m_offset != notFound)
 146             ASSERT(result.m_structureSet.size());
 147         break;
 148     }
 149
 150     default:
 151         ASSERT(result.m_offset == notFound);
 152         break;
 153     }
 154
 155     if (result.m_offset == notFound) {
 156         result.m_state = TakesSlowPath;
 157         result.m_structureSet.clear();
 158     } else
 159         result.m_state = SimpleDirect;
 160
 161     return result;
 162 #else // ENABLE(JIT)
 163     return GetByIdStatus(NoInformation, StructureSet(), notFound, false);
 164 #endif // ENABLE(JIT)
 165 }
 166
 167 } // namespace JSC
 168