runtime/FunctionRareData.cpp

   1 /*
   2  * Copyright (C) 2015 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 "FunctionRareData.h"
  28
  29 #include "JSCInlines.h"
  30
  31 namespace JSC {
  32
  33 const ClassInfo FunctionRareData::s_info = { "FunctionRareData", 0, 0, CREATE_METHOD_TABLE(FunctionRareData) };
  34
  35 FunctionRareData* FunctionRareData::create(VM& vm, JSObject* prototype, size_t inlineCapacity)
  36 {
  37     FunctionRareData* rareData = new (NotNull, allocateCell<FunctionRareData>(vm.heap)) FunctionRareData(vm);
  38     rareData->finishCreation(vm, prototype, inlineCapacity);
  39     return rareData;
  40 }
  41
  42 void FunctionRareData::destroy(JSCell* cell)
  43 {
  44     FunctionRareData* rareData = static_cast<FunctionRareData*>(cell);
  45     rareData->FunctionRareData::~FunctionRareData();
  46 }
  47
  48 Structure* FunctionRareData::createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
  49 {
  50     return Structure::create(vm, globalObject, prototype, TypeInfo(CellType, StructureFlags), info());
  51 }
  52
  53 void FunctionRareData::visitChildren(JSCell* cell, SlotVisitor& visitor)
  54 {
  55     FunctionRareData* rareData = jsCast<FunctionRareData*>(cell);
  56
  57     rareData->m_allocationProfile.visitAggregate(visitor);
  58 }
  59
  60 FunctionRareData::FunctionRareData(VM& vm)
  61     : Base(vm, vm.functionRareDataStructure.get())
  62     , m_allocationProfile()
  63     // We initialize blind so that changes to the prototype after function creation but before
  64     // the optimizer kicks in don't disable optimizations. Once the optimizer kicks in, the
  65     // watchpoint will start watching and any changes will both force deoptimization and disable
  66     // future attempts to optimize. This is necessary because we are guaranteed that the
  67     // allocation profile is changed exactly once prior to optimizations kicking in. We could be
  68     // smarter and count the number of times the prototype is clobbered and only optimize if it
  69     // was clobbered exactly once, but that seems like overkill. In almost all cases it will be
  70     // clobbered once, and if it's clobbered more than once, that will probably only occur
  71     // before we started optimizing, anyway.
  72     , m_allocationProfileWatchpoint(ClearWatchpoint)
  73 {
  74 }
  75
  76 FunctionRareData::~FunctionRareData()
  77 {
  78 }
  79
  80 void FunctionRareData::finishCreation(VM& vm, JSObject* prototype, size_t inlineCapacity)
  81 {
  82     Base::finishCreation(vm);
  83     initialize(vm, prototype, inlineCapacity);
  84 }
  85
  86 void FunctionRareData::initialize(VM& vm, JSObject* prototype, size_t inlineCapacity)
  87 {
  88     m_allocationProfile.initialize(vm, this, prototype, inlineCapacity);
  89 }
  90
  91 void FunctionRareData::clear(const char* reason)
  92 {
  93     m_allocationProfile.clear();
  94     m_allocationProfileWatchpoint.fireAll(reason);
  95 }
  96
  97 }