]> git.saurik.com Git - apple/javascriptcore.git/blobdiff - jit/JITPropertyAccess32_64.cpp
JavaScriptCore-1218.34.tar.gz
[apple/javascriptcore.git] / jit / JITPropertyAccess32_64.cpp
index 059c9c5c9382264503ef6ebd744e58e16787004b..1cc98ef66c9f69bca30916bf2adc6adaf4cc4790 100644 (file)
 
 #include "config.h"
 
+#if ENABLE(JIT)
 #if USE(JSVALUE32_64)
-
 #include "JIT.h"
 
-#if ENABLE(JIT)
-
 #include "CodeBlock.h"
-#include "JITInlineMethods.h"
+#include "GCAwareJITStubRoutine.h"
+#include "Interpreter.h"
+#include "JITInlines.h"
 #include "JITStubCall.h"
 #include "JSArray.h"
 #include "JSFunction.h"
 #include "JSPropertyNameIterator.h"
-#include "Interpreter.h"
+#include "JSVariableObject.h"
 #include "LinkBuffer.h"
 #include "RepatchBuffer.h"
 #include "ResultType.h"
 #include "SamplingTool.h"
+#include <wtf/StringPrintStream.h>
 
 #ifndef NDEBUG
 #include <stdio.h>
@@ -59,34 +60,23 @@ void JIT::emit_op_put_by_index(Instruction* currentInstruction)
     
     JITStubCall stubCall(this, cti_op_put_by_index);
     stubCall.addArgument(base);
-    stubCall.addArgument(Imm32(property));
+    stubCall.addArgument(TrustedImm32(property));
     stubCall.addArgument(value);
     stubCall.call();
 }
 
-void JIT::emit_op_put_getter(Instruction* currentInstruction)
-{
-    unsigned base = currentInstruction[1].u.operand;
-    unsigned property = currentInstruction[2].u.operand;
-    unsigned function = currentInstruction[3].u.operand;
-    
-    JITStubCall stubCall(this, cti_op_put_getter);
-    stubCall.addArgument(base);
-    stubCall.addArgument(ImmPtr(&m_codeBlock->identifier(property)));
-    stubCall.addArgument(function);
-    stubCall.call();
-}
-
-void JIT::emit_op_put_setter(Instruction* currentInstruction)
+void JIT::emit_op_put_getter_setter(Instruction* currentInstruction)
 {
     unsigned base = currentInstruction[1].u.operand;
     unsigned property = currentInstruction[2].u.operand;
-    unsigned function = currentInstruction[3].u.operand;
+    unsigned getter = currentInstruction[3].u.operand;
+    unsigned setter = currentInstruction[4].u.operand;
     
-    JITStubCall stubCall(this, cti_op_put_setter);
+    JITStubCall stubCall(this, cti_op_put_getter_setter);
     stubCall.addArgument(base);
-    stubCall.addArgument(ImmPtr(&m_codeBlock->identifier(property)));
-    stubCall.addArgument(function);
+    stubCall.addArgument(TrustedImmPtr(&m_codeBlock->identifier(property)));
+    stubCall.addArgument(getter);
+    stubCall.addArgument(setter);
     stubCall.call();
 }
 
@@ -98,293 +88,333 @@ void JIT::emit_op_del_by_id(Instruction* currentInstruction)
     
     JITStubCall stubCall(this, cti_op_del_by_id);
     stubCall.addArgument(base);
-    stubCall.addArgument(ImmPtr(&m_codeBlock->identifier(property)));
-    stubCall.call(dst);
-}
-
-
-#if !ENABLE(JIT_OPTIMIZE_PROPERTY_ACCESS)
-
-/* ------------------------------ BEGIN: !ENABLE(JIT_OPTIMIZE_PROPERTY_ACCESS) ------------------------------ */
-
-// Treat these as nops - the call will be handed as a regular get_by_id/op_call pair.
-void JIT::emit_op_method_check(Instruction*) {}
-void JIT::emitSlow_op_method_check(Instruction*, Vector<SlowCaseEntry>::iterator&) { ASSERT_NOT_REACHED(); }
-#if ENABLE(JIT_OPTIMIZE_METHOD_CALLS)
-#error "JIT_OPTIMIZE_METHOD_CALLS requires JIT_OPTIMIZE_PROPERTY_ACCESS"
-#endif
-
-void JIT::emit_op_get_by_val(Instruction* currentInstruction)
-{
-    unsigned dst = currentInstruction[1].u.operand;
-    unsigned base = currentInstruction[2].u.operand;
-    unsigned property = currentInstruction[3].u.operand;
-    
-    JITStubCall stubCall(this, cti_op_get_by_val);
-    stubCall.addArgument(base);
-    stubCall.addArgument(property);
+    stubCall.addArgument(TrustedImmPtr(&m_codeBlock->identifier(property)));
     stubCall.call(dst);
 }
 
-void JIT::emitSlow_op_get_by_val(Instruction*, Vector<SlowCaseEntry>::iterator&)
-{
-    ASSERT_NOT_REACHED();
-}
-
-void JIT::emit_op_put_by_val(Instruction* currentInstruction)
+JIT::CodeRef JIT::stringGetByValStubGenerator(VM* vm)
 {
-    unsigned base = currentInstruction[1].u.operand;
-    unsigned property = currentInstruction[2].u.operand;
-    unsigned value = currentInstruction[3].u.operand;
+    JSInterfaceJIT jit;
+    JumpList failures;
+    failures.append(jit.branchPtr(NotEqual, Address(regT0, JSCell::structureOffset()), TrustedImmPtr(vm->stringStructure.get())));
     
-    JITStubCall stubCall(this, cti_op_put_by_val);
-    stubCall.addArgument(base);
-    stubCall.addArgument(property);
-    stubCall.addArgument(value);
-    stubCall.call();
-}
-
-void JIT::emitSlow_op_put_by_val(Instruction*, Vector<SlowCaseEntry>::iterator&)
-{
-    ASSERT_NOT_REACHED();
-}
-
-void JIT::emit_op_get_by_id(Instruction* currentInstruction)
-{
-    int dst = currentInstruction[1].u.operand;
-    int base = currentInstruction[2].u.operand;
-    int ident = currentInstruction[3].u.operand;
+    // Load string length to regT1, and start the process of loading the data pointer into regT0
+    jit.load32(Address(regT0, ThunkHelpers::jsStringLengthOffset()), regT1);
+    jit.loadPtr(Address(regT0, ThunkHelpers::jsStringValueOffset()), regT0);
+    failures.append(jit.branchTest32(Zero, regT0));
     
-    JITStubCall stubCall(this, cti_op_get_by_id_generic);
-    stubCall.addArgument(base);
-    stubCall.addArgument(ImmPtr(&(m_codeBlock->identifier(ident))));
-    stubCall.call(dst);
+    // Do an unsigned compare to simultaneously filter negative indices as well as indices that are too large
+    failures.append(jit.branch32(AboveOrEqual, regT2, regT1));
     
-    m_propertyAccessInstructionIndex++;
-}
-
-void JIT::emitSlow_op_get_by_id(Instruction*, Vector<SlowCaseEntry>::iterator&)
-{
-    m_propertyAccessInstructionIndex++;
-    ASSERT_NOT_REACHED();
-}
+    // Load the character
+    JumpList is16Bit;
+    JumpList cont8Bit;
+    // Load the string flags
+    jit.loadPtr(Address(regT0, StringImpl::flagsOffset()), regT1);
+    jit.loadPtr(Address(regT0, StringImpl::dataOffset()), regT0);
+    is16Bit.append(jit.branchTest32(Zero, regT1, TrustedImm32(StringImpl::flagIs8Bit())));
+    jit.load8(BaseIndex(regT0, regT2, TimesOne, 0), regT0);
+    cont8Bit.append(jit.jump());
+    is16Bit.link(&jit);
+    jit.load16(BaseIndex(regT0, regT2, TimesTwo, 0), regT0);
 
-void JIT::emit_op_put_by_id(Instruction* currentInstruction)
-{
-    int base = currentInstruction[1].u.operand;
-    int ident = currentInstruction[2].u.operand;
-    int value = currentInstruction[3].u.operand;
-    
-    JITStubCall stubCall(this, cti_op_put_by_id_generic);
-    stubCall.addArgument(base);
-    stubCall.addArgument(ImmPtr(&(m_codeBlock->identifier(ident))));
-    stubCall.addArgument(value);
-    stubCall.call();
+    cont8Bit.link(&jit);
     
-    m_propertyAccessInstructionIndex++;
-}
+    failures.append(jit.branch32(AboveOrEqual, regT0, TrustedImm32(0x100)));
+    jit.move(TrustedImmPtr(vm->smallStrings.singleCharacterStrings()), regT1);
+    jit.loadPtr(BaseIndex(regT1, regT0, ScalePtr, 0), regT0);
+    jit.move(TrustedImm32(JSValue::CellTag), regT1); // We null check regT0 on return so this is safe
+    jit.ret();
 
-void JIT::emitSlow_op_put_by_id(Instruction*, Vector<SlowCaseEntry>::iterator&)
-{
-    m_propertyAccessInstructionIndex++;
-    ASSERT_NOT_REACHED();
+    failures.link(&jit);
+    jit.move(TrustedImm32(0), regT0);
+    jit.ret();
+    
+    LinkBuffer patchBuffer(*vm, &jit, GLOBAL_THUNK_ID);
+    return FINALIZE_CODE(patchBuffer, ("String get_by_val stub"));
 }
 
-#else // !ENABLE(JIT_OPTIMIZE_PROPERTY_ACCESS)
-
-/* ------------------------------ BEGIN: ENABLE(JIT_OPTIMIZE_PROPERTY_ACCESS) ------------------------------ */
-
-#if ENABLE(JIT_OPTIMIZE_METHOD_CALLS)
-
-void JIT::emit_op_method_check(Instruction* currentInstruction)
+void JIT::emit_op_get_by_val(Instruction* currentInstruction)
 {
-    // Assert that the following instruction is a get_by_id.
-    ASSERT(m_interpreter->getOpcodeID((currentInstruction + OPCODE_LENGTH(op_method_check))->u.opcode) == op_get_by_id);
-    
-    currentInstruction += OPCODE_LENGTH(op_method_check);
-    
-    // Do the method check - check the object & its prototype's structure inline (this is the common case).
-    m_methodCallCompilationInfo.append(MethodCallCompilationInfo(m_propertyAccessInstructionIndex));
-    MethodCallCompilationInfo& info = m_methodCallCompilationInfo.last();
+    unsigned dst = currentInstruction[1].u.operand;
+    unsigned base = currentInstruction[2].u.operand;
+    unsigned property = currentInstruction[3].u.operand;
+    ArrayProfile* profile = currentInstruction[4].u.arrayProfile;
     
-    int dst = currentInstruction[1].u.operand;
-    int base = currentInstruction[2].u.operand;
+    emitLoad2(base, regT1, regT0, property, regT3, regT2);
     
-    emitLoad(base, regT1, regT0);
+    addSlowCase(branch32(NotEqual, regT3, TrustedImm32(JSValue::Int32Tag)));
     emitJumpSlowCaseIfNotJSCell(base, regT1);
+    loadPtr(Address(regT0, JSCell::structureOffset()), regT1);
+    emitArrayProfilingSite(regT1, regT3, profile);
+    and32(TrustedImm32(IndexingShapeMask), regT1);
+
+    PatchableJump badType;
+    JumpList slowCases;
+    
+    JITArrayMode mode = chooseArrayMode(profile);
+    switch (mode) {
+    case JITInt32:
+        slowCases = emitInt32GetByVal(currentInstruction, badType);
+        break;
+    case JITDouble:
+        slowCases = emitDoubleGetByVal(currentInstruction, badType);
+        break;
+    case JITContiguous:
+        slowCases = emitContiguousGetByVal(currentInstruction, badType);
+        break;
+    case JITArrayStorage:
+        slowCases = emitArrayStorageGetByVal(currentInstruction, badType);
+        break;
+    default:
+        CRASH();
+    }
     
-    BEGIN_UNINTERRUPTED_SEQUENCE(sequenceMethodCheck);
-    
-    Jump structureCheck = branchPtrWithPatch(NotEqual, Address(regT0, OBJECT_OFFSETOF(JSCell, m_structure)), info.structureToCompare, ImmPtr(reinterpret_cast<void*>(patchGetByIdDefaultStructure)));
-    DataLabelPtr protoStructureToCompare, protoObj = moveWithPatch(ImmPtr(0), regT2);
-    Jump protoStructureCheck = branchPtrWithPatch(NotEqual, Address(regT2, OBJECT_OFFSETOF(JSCell, m_structure)), protoStructureToCompare, ImmPtr(reinterpret_cast<void*>(patchGetByIdDefaultStructure)));
-    
-    // This will be relinked to load the function without doing a load.
-    DataLabelPtr putFunction = moveWithPatch(ImmPtr(0), regT0);
-    
-    END_UNINTERRUPTED_SEQUENCE(sequenceMethodCheck);
-    
-    move(Imm32(JSValue::CellTag), regT1);
-    Jump match = jump();
-    
-    ASSERT(differenceBetween(info.structureToCompare, protoObj) == patchOffsetMethodCheckProtoObj);
-    ASSERT(differenceBetween(info.structureToCompare, protoStructureToCompare) == patchOffsetMethodCheckProtoStruct);
-    ASSERT(differenceBetween(info.structureToCompare, putFunction) == patchOffsetMethodCheckPutFunction);
-    
-    // Link the failure cases here.
-    structureCheck.link(this);
-    protoStructureCheck.link(this);
-    
-    // Do a regular(ish) get_by_id (the slow case will be link to
-    // cti_op_get_by_id_method_check instead of cti_op_get_by_id.
-    compileGetByIdHotPath();
+    addSlowCase(badType);
+    addSlowCase(slowCases);
     
-    match.link(this);
+    Label done = label();
+
+#if !ASSERT_DISABLED
+    Jump resultOK = branch32(NotEqual, regT1, TrustedImm32(JSValue::EmptyValueTag));
+    breakpoint();
+    resultOK.link(this);
+#endif
+
+    emitValueProfilingSite();
     emitStore(dst, regT1, regT0);
-    map(m_bytecodeIndex + OPCODE_LENGTH(op_method_check), dst, regT1, regT0);
+    map(m_bytecodeOffset + OPCODE_LENGTH(op_get_by_val), dst, regT1, regT0);
     
-    // We've already generated the following get_by_id, so make sure it's skipped over.
-    m_bytecodeIndex += OPCODE_LENGTH(op_get_by_id);
+    m_byValCompilationInfo.append(ByValCompilationInfo(m_bytecodeOffset, badType, mode, done));
 }
 
-void JIT::emitSlow_op_method_check(Instruction* currentInstruction, Vector<SlowCaseEntry>::iterator& iter)
+JIT::JumpList JIT::emitContiguousGetByVal(Instruction*, PatchableJump& badType, IndexingType expectedShape)
 {
-    currentInstruction += OPCODE_LENGTH(op_method_check);
+    JumpList slowCases;
     
-    int dst = currentInstruction[1].u.operand;
-    int base = currentInstruction[2].u.operand;
-    int ident = currentInstruction[3].u.operand;
+    badType = patchableBranch32(NotEqual, regT1, TrustedImm32(expectedShape));
     
-    compileGetByIdSlowCase(dst, base, &(m_codeBlock->identifier(ident)), iter, true);
+    loadPtr(Address(regT0, JSObject::butterflyOffset()), regT3);
+    slowCases.append(branch32(AboveOrEqual, regT2, Address(regT3, Butterfly::offsetOfPublicLength())));
     
-    // We've already generated the following get_by_id, so make sure it's skipped over.
-    m_bytecodeIndex += OPCODE_LENGTH(op_get_by_id);
+    load32(BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.tag)), regT1); // tag
+    load32(BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.payload)), regT0); // payload
+    slowCases.append(branch32(Equal, regT1, TrustedImm32(JSValue::EmptyValueTag)));
+    
+    return slowCases;
 }
 
-#else //!ENABLE(JIT_OPTIMIZE_METHOD_CALLS)
-
-// Treat these as nops - the call will be handed as a regular get_by_id/op_call pair.
-void JIT::emit_op_method_check(Instruction*) {}
-void JIT::emitSlow_op_method_check(Instruction*, Vector<SlowCaseEntry>::iterator&) { ASSERT_NOT_REACHED(); }
-
-#endif
-
-PassRefPtr<NativeExecutable> JIT::stringGetByValStubGenerator(JSGlobalData* globalData, ExecutablePool* pool)
+JIT::JumpList JIT::emitDoubleGetByVal(Instruction*, PatchableJump& badType)
 {
-    JSInterfaceJIT jit;
-    JumpList failures;
-    failures.append(jit.branchPtr(NotEqual, Address(regT0), ImmPtr(globalData->jsStringVPtr)));
-    failures.append(jit.branchTest32(NonZero, Address(regT0, OBJECT_OFFSETOF(JSString, m_fiberCount))));
+    JumpList slowCases;
     
-    // Load string length to regT1, and start the process of loading the data pointer into regT0
-    jit.load32(Address(regT0, ThunkHelpers::jsStringLengthOffset()), regT1);
-    jit.loadPtr(Address(regT0, ThunkHelpers::jsStringValueOffset()), regT0);
-    jit.loadPtr(Address(regT0, ThunkHelpers::stringImplDataOffset()), regT0);
+    badType = patchableBranch32(NotEqual, regT1, TrustedImm32(DoubleShape));
     
-    // Do an unsigned compare to simultaneously filter negative indices as well as indices that are too large
-    failures.append(jit.branch32(AboveOrEqual, regT2, regT1));
-    
-    // Load the character
-    jit.load16(BaseIndex(regT0, regT2, TimesTwo, 0), regT0);
+    loadPtr(Address(regT0, JSObject::butterflyOffset()), regT3);
+    slowCases.append(branch32(AboveOrEqual, regT2, Address(regT3, Butterfly::offsetOfPublicLength())));
     
-    failures.append(jit.branch32(AboveOrEqual, regT0, Imm32(0x100)));
-    jit.move(ImmPtr(globalData->smallStrings.singleCharacterStrings()), regT1);
-    jit.loadPtr(BaseIndex(regT1, regT0, ScalePtr, 0), regT0);
-    jit.move(Imm32(JSValue::CellTag), regT1); // We null check regT0 on return so this is safe
-    jit.ret();
-
-    failures.link(&jit);
-    jit.move(Imm32(0), regT0);
-    jit.ret();
+    loadDouble(BaseIndex(regT3, regT2, TimesEight), fpRegT0);
+    slowCases.append(branchDouble(DoubleNotEqualOrUnordered, fpRegT0, fpRegT0));
+    moveDoubleToInts(fpRegT0, regT0, regT1);
     
-    LinkBuffer patchBuffer(&jit, pool, 0);
-    return adoptRef(new NativeExecutable(patchBuffer.finalizeCode()));
+    return slowCases;
 }
 
-void JIT::emit_op_get_by_val(Instruction* currentInstruction)
+JIT::JumpList JIT::emitArrayStorageGetByVal(Instruction*, PatchableJump& badType)
 {
-    unsigned dst = currentInstruction[1].u.operand;
-    unsigned base = currentInstruction[2].u.operand;
-    unsigned property = currentInstruction[3].u.operand;
-    
-    emitLoad2(base, regT1, regT0, property, regT3, regT2);
+    JumpList slowCases;
     
-    addSlowCase(branch32(NotEqual, regT3, Imm32(JSValue::Int32Tag)));
-    emitJumpSlowCaseIfNotJSCell(base, regT1);
-    addSlowCase(branchPtr(NotEqual, Address(regT0), ImmPtr(m_globalData->jsArrayVPtr)));
+    add32(TrustedImm32(-ArrayStorageShape), regT1, regT3);
+    badType = patchableBranch32(Above, regT3, TrustedImm32(SlowPutArrayStorageShape - ArrayStorageShape));
     
-    loadPtr(Address(regT0, OBJECT_OFFSETOF(JSArray, m_storage)), regT3);
-    addSlowCase(branch32(AboveOrEqual, regT2, Address(regT0, OBJECT_OFFSETOF(JSArray, m_vectorLength))));
+    loadPtr(Address(regT0, JSObject::butterflyOffset()), regT3);
+    slowCases.append(branch32(AboveOrEqual, regT2, Address(regT3, ArrayStorage::vectorLengthOffset())));
     
-    load32(BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(ArrayStorage, m_vector[0]) + 4), regT1); // tag
-    load32(BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(ArrayStorage, m_vector[0])), regT0); // payload
-    addSlowCase(branch32(Equal, regT1, Imm32(JSValue::EmptyValueTag)));
+    load32(BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(ArrayStorage, m_vector[0]) + OBJECT_OFFSETOF(JSValue, u.asBits.tag)), regT1); // tag
+    load32(BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(ArrayStorage, m_vector[0]) + OBJECT_OFFSETOF(JSValue, u.asBits.payload)), regT0); // payload
+    slowCases.append(branch32(Equal, regT1, TrustedImm32(JSValue::EmptyValueTag)));
     
-    emitStore(dst, regT1, regT0);
-    map(m_bytecodeIndex + OPCODE_LENGTH(op_get_by_val), dst, regT1, regT0);
+    return slowCases;
 }
-
+    
 void JIT::emitSlow_op_get_by_val(Instruction* currentInstruction, Vector<SlowCaseEntry>::iterator& iter)
 {
     unsigned dst = currentInstruction[1].u.operand;
     unsigned base = currentInstruction[2].u.operand;
     unsigned property = currentInstruction[3].u.operand;
+    ArrayProfile* profile = currentInstruction[4].u.arrayProfile;
     
     linkSlowCase(iter); // property int32 check
     linkSlowCaseIfNotJSCell(iter, base); // base cell check
 
     Jump nonCell = jump();
     linkSlowCase(iter); // base array check
-    Jump notString = branchPtr(NotEqual, Address(regT0), ImmPtr(m_globalData->jsStringVPtr));
-    emitNakedCall(m_globalData->getThunk(stringGetByValStubGenerator)->generatedJITCode().addressForCall());
+    Jump notString = branchPtr(NotEqual, Address(regT0, JSCell::structureOffset()), TrustedImmPtr(m_vm->stringStructure.get()));
+    emitNakedCall(m_vm->getCTIStub(stringGetByValStubGenerator).code());
     Jump failed = branchTestPtr(Zero, regT0);
     emitStore(dst, regT1, regT0);
     emitJumpSlowToHot(jump(), OPCODE_LENGTH(op_get_by_val));
     failed.link(this);
     notString.link(this);
     nonCell.link(this);
+    
+    Jump skipProfiling = jump();
 
     linkSlowCase(iter); // vector length check
     linkSlowCase(iter); // empty value
     
+    emitArrayProfileOutOfBoundsSpecialCase(profile);
+    
+    skipProfiling.link(this);
+    
+    Label slowPath = label();
+    
     JITStubCall stubCall(this, cti_op_get_by_val);
     stubCall.addArgument(base);
     stubCall.addArgument(property);
-    stubCall.call(dst);
+    Call call = stubCall.call(dst);
+
+    m_byValCompilationInfo[m_byValInstructionIndex].slowPathTarget = slowPath;
+    m_byValCompilationInfo[m_byValInstructionIndex].returnAddress = call;
+    m_byValInstructionIndex++;
+
+    emitValueProfilingSite();
 }
 
 void JIT::emit_op_put_by_val(Instruction* currentInstruction)
 {
     unsigned base = currentInstruction[1].u.operand;
     unsigned property = currentInstruction[2].u.operand;
-    unsigned value = currentInstruction[3].u.operand;
+    ArrayProfile* profile = currentInstruction[4].u.arrayProfile;
     
     emitLoad2(base, regT1, regT0, property, regT3, regT2);
     
-    addSlowCase(branch32(NotEqual, regT3, Imm32(JSValue::Int32Tag)));
+    addSlowCase(branch32(NotEqual, regT3, TrustedImm32(JSValue::Int32Tag)));
     emitJumpSlowCaseIfNotJSCell(base, regT1);
-    addSlowCase(branchPtr(NotEqual, Address(regT0), ImmPtr(m_globalData->jsArrayVPtr)));
-    addSlowCase(branch32(AboveOrEqual, regT2, Address(regT0, OBJECT_OFFSETOF(JSArray, m_vectorLength))));
+    loadPtr(Address(regT0, JSCell::structureOffset()), regT1);
+    emitArrayProfilingSite(regT1, regT3, profile);
+    and32(TrustedImm32(IndexingShapeMask), regT1);
+    
+    PatchableJump badType;
+    JumpList slowCases;
+    
+    JITArrayMode mode = chooseArrayMode(profile);
+    switch (mode) {
+    case JITInt32:
+        slowCases = emitInt32PutByVal(currentInstruction, badType);
+        break;
+    case JITDouble:
+        slowCases = emitDoublePutByVal(currentInstruction, badType);
+        break;
+    case JITContiguous:
+        slowCases = emitContiguousPutByVal(currentInstruction, badType);
+        break;
+    case JITArrayStorage:
+        slowCases = emitArrayStoragePutByVal(currentInstruction, badType);
+        break;
+    default:
+        CRASH();
+        break;
+    }
     
-    loadPtr(Address(regT0, OBJECT_OFFSETOF(JSArray, m_storage)), regT3);
+    addSlowCase(badType);
+    addSlowCase(slowCases);
     
-    Jump empty = branch32(Equal, BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(ArrayStorage, m_vector[0]) + 4), Imm32(JSValue::EmptyValueTag));
+    Label done = label();
+    
+    m_byValCompilationInfo.append(ByValCompilationInfo(m_bytecodeOffset, badType, mode, done));
+}
+
+JIT::JumpList JIT::emitGenericContiguousPutByVal(Instruction* currentInstruction, PatchableJump& badType, IndexingType indexingShape)
+{
+    unsigned value = currentInstruction[3].u.operand;
+    ArrayProfile* profile = currentInstruction[4].u.arrayProfile;
+    
+    JumpList slowCases;
+    
+    badType = patchableBranch32(NotEqual, regT1, TrustedImm32(ContiguousShape));
+    
+    loadPtr(Address(regT0, JSObject::butterflyOffset()), regT3);
+    Jump outOfBounds = branch32(AboveOrEqual, regT2, Address(regT3, Butterfly::offsetOfPublicLength()));
+    
+    Label storeResult = label();
+    emitLoad(value, regT1, regT0);
+    switch (indexingShape) {
+    case Int32Shape:
+        slowCases.append(branch32(NotEqual, regT1, TrustedImm32(JSValue::Int32Tag)));
+        // Fall through.
+    case ContiguousShape:
+        store32(regT0, BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.payload)));
+        store32(regT1, BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.tag)));
+        break;
+    case DoubleShape: {
+        Jump notInt = branch32(NotEqual, regT1, TrustedImm32(JSValue::Int32Tag));
+        convertInt32ToDouble(regT0, fpRegT0);
+        Jump ready = jump();
+        notInt.link(this);
+        moveIntsToDouble(regT0, regT1, fpRegT0, fpRegT1);
+        slowCases.append(branchDouble(DoubleNotEqualOrUnordered, fpRegT0, fpRegT0));
+        ready.link(this);
+        storeDouble(fpRegT0, BaseIndex(regT3, regT2, TimesEight));
+        break;
+    }
+    default:
+        CRASH();
+        break;
+    }
+        
+    Jump done = jump();
+    
+    outOfBounds.link(this);
+    slowCases.append(branch32(AboveOrEqual, regT2, Address(regT3, Butterfly::offsetOfVectorLength())));
+    
+    emitArrayProfileStoreToHoleSpecialCase(profile);
+    
+    add32(TrustedImm32(1), regT2, regT1);
+    store32(regT1, Address(regT3, Butterfly::offsetOfPublicLength()));
+    jump().linkTo(storeResult, this);
+    
+    done.link(this);
+    
+    emitWriteBarrier(regT0, regT1, regT1, regT3, UnconditionalWriteBarrier, WriteBarrierForPropertyAccess);
+    
+    return slowCases;
+}
+
+JIT::JumpList JIT::emitArrayStoragePutByVal(Instruction* currentInstruction, PatchableJump& badType)
+{
+    unsigned value = currentInstruction[3].u.operand;
+    ArrayProfile* profile = currentInstruction[4].u.arrayProfile;
+    
+    JumpList slowCases;
+    
+    badType = patchableBranch32(NotEqual, regT1, TrustedImm32(ArrayStorageShape));
+    
+    loadPtr(Address(regT0, JSObject::butterflyOffset()), regT3);
+    slowCases.append(branch32(AboveOrEqual, regT2, Address(regT3, ArrayStorage::vectorLengthOffset())));
+
+    Jump empty = branch32(Equal, BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(ArrayStorage, m_vector[0]) + OBJECT_OFFSETOF(JSValue, u.asBits.tag)), TrustedImm32(JSValue::EmptyValueTag));
     
     Label storeResult(this);
     emitLoad(value, regT1, regT0);
-    store32(regT0, BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(ArrayStorage, m_vector[0]))); // payload
-    store32(regT1, BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(ArrayStorage, m_vector[0]) + 4)); // tag
+    store32(regT0, BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(ArrayStorage, m_vector[0]) + OBJECT_OFFSETOF(JSValue, u.asBits.payload))); // payload
+    store32(regT1, BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(ArrayStorage, m_vector[0]) + OBJECT_OFFSETOF(JSValue, u.asBits.tag))); // tag
     Jump end = jump();
     
     empty.link(this);
-    add32(Imm32(1), Address(regT3, OBJECT_OFFSETOF(ArrayStorage, m_numValuesInVector)));
-    branch32(Below, regT2, Address(regT3, OBJECT_OFFSETOF(ArrayStorage, m_length))).linkTo(storeResult, this);
+    emitArrayProfileStoreToHoleSpecialCase(profile);
+    add32(TrustedImm32(1), Address(regT3, OBJECT_OFFSETOF(ArrayStorage, m_numValuesInVector)));
+    branch32(Below, regT2, Address(regT3, ArrayStorage::lengthOffset())).linkTo(storeResult, this);
     
-    add32(Imm32(1), regT2, regT0);
-    store32(regT0, Address(regT3, OBJECT_OFFSETOF(ArrayStorage, m_length)));
+    add32(TrustedImm32(1), regT2, regT0);
+    store32(regT0, Address(regT3, ArrayStorage::lengthOffset()));
     jump().linkTo(storeResult, this);
     
     end.link(this);
+    
+    emitWriteBarrier(regT0, regT1, regT1, regT3, UnconditionalWriteBarrier, WriteBarrierForPropertyAccess);
+    
+    return slowCases;
 }
 
 void JIT::emitSlow_op_put_by_val(Instruction* currentInstruction, Vector<SlowCaseEntry>::iterator& iter)
@@ -392,64 +422,83 @@ void JIT::emitSlow_op_put_by_val(Instruction* currentInstruction, Vector<SlowCas
     unsigned base = currentInstruction[1].u.operand;
     unsigned property = currentInstruction[2].u.operand;
     unsigned value = currentInstruction[3].u.operand;
+    ArrayProfile* profile = currentInstruction[4].u.arrayProfile;
     
     linkSlowCase(iter); // property int32 check
     linkSlowCaseIfNotJSCell(iter, base); // base cell check
     linkSlowCase(iter); // base not array check
-    linkSlowCase(iter); // in vector check
+    
+    JITArrayMode mode = chooseArrayMode(profile);
+    switch (mode) {
+    case JITInt32:
+    case JITDouble:
+        linkSlowCase(iter); // value type check
+        break;
+    default:
+        break;
+    }
+    
+    Jump skipProfiling = jump();
+    linkSlowCase(iter); // out of bounds
+    emitArrayProfileOutOfBoundsSpecialCase(profile);
+    skipProfiling.link(this);
+
+    Label slowPath = label();
     
     JITStubCall stubPutByValCall(this, cti_op_put_by_val);
     stubPutByValCall.addArgument(base);
     stubPutByValCall.addArgument(property);
     stubPutByValCall.addArgument(value);
-    stubPutByValCall.call();
+    Call call = stubPutByValCall.call();
+    
+    m_byValCompilationInfo[m_byValInstructionIndex].slowPathTarget = slowPath;
+    m_byValCompilationInfo[m_byValInstructionIndex].returnAddress = call;
+    m_byValInstructionIndex++;
 }
 
 void JIT::emit_op_get_by_id(Instruction* currentInstruction)
 {
     int dst = currentInstruction[1].u.operand;
     int base = currentInstruction[2].u.operand;
+    Identifier* ident = &(m_codeBlock->identifier(currentInstruction[3].u.operand));
     
     emitLoad(base, regT1, regT0);
     emitJumpSlowCaseIfNotJSCell(base, regT1);
-    compileGetByIdHotPath();
+    compileGetByIdHotPath(ident);
+    emitValueProfilingSite();
     emitStore(dst, regT1, regT0);
-    map(m_bytecodeIndex + OPCODE_LENGTH(op_get_by_id), dst, regT1, regT0);
+    map(m_bytecodeOffset + OPCODE_LENGTH(op_get_by_id), dst, regT1, regT0);
 }
 
-void JIT::compileGetByIdHotPath()
+void JIT::compileGetByIdHotPath(Identifier* ident)
 {
     // As for put_by_id, get_by_id requires the offset of the Structure and the offset of the access to be patched.
     // Additionally, for get_by_id we need patch the offset of the branch to the slow case (we patch this to jump
     // to array-length / prototype access tranpolines, and finally we also the the property-map access offset as a label
     // to jump back to if one of these trampolies finds a match.
     
+    if (*ident == m_vm->propertyNames->length && shouldEmitProfiling()) {
+        loadPtr(Address(regT0, JSCell::structureOffset()), regT2);
+        emitArrayProfilingSiteForBytecodeIndex(regT2, regT3, m_bytecodeOffset);
+    }
+
     BEGIN_UNINTERRUPTED_SEQUENCE(sequenceGetByIdHotPath);
     
     Label hotPathBegin(this);
-    m_propertyAccessCompilationInfo[m_propertyAccessInstructionIndex].hotPathBegin = hotPathBegin;
-    m_propertyAccessInstructionIndex++;
     
     DataLabelPtr structureToCompare;
-    Jump structureCheck = branchPtrWithPatch(NotEqual, Address(regT0, OBJECT_OFFSETOF(JSCell, m_structure)), structureToCompare, ImmPtr(reinterpret_cast<void*>(patchGetByIdDefaultStructure)));
+    PatchableJump structureCheck = patchableBranchPtrWithPatch(NotEqual, Address(regT0, JSCell::structureOffset()), structureToCompare, TrustedImmPtr(reinterpret_cast<void*>(patchGetByIdDefaultStructure)));
     addSlowCase(structureCheck);
-    ASSERT(differenceBetween(hotPathBegin, structureToCompare) == patchOffsetGetByIdStructure);
-    ASSERT(differenceBetween(hotPathBegin, structureCheck) == patchOffsetGetByIdBranchToSlowCase);
     
-    Label externalLoad = loadPtrWithPatchToLEA(Address(regT0, OBJECT_OFFSETOF(JSObject, m_externalStorage)), regT2);
-    Label externalLoadComplete(this);
-    ASSERT(differenceBetween(hotPathBegin, externalLoad) == patchOffsetGetByIdExternalLoad);
-    ASSERT(differenceBetween(externalLoad, externalLoadComplete) == patchLengthGetByIdExternalLoad);
-    
-    DataLabel32 displacementLabel1 = loadPtrWithAddressOffsetPatch(Address(regT2, patchGetByIdDefaultOffset), regT0); // payload
-    ASSERT(differenceBetween(hotPathBegin, displacementLabel1) == patchOffsetGetByIdPropertyMapOffset1);
-    DataLabel32 displacementLabel2 = loadPtrWithAddressOffsetPatch(Address(regT2, patchGetByIdDefaultOffset), regT1); // tag
-    ASSERT(differenceBetween(hotPathBegin, displacementLabel2) == patchOffsetGetByIdPropertyMapOffset2);
+    ConvertibleLoadLabel propertyStorageLoad = convertibleLoadPtr(Address(regT0, JSObject::butterflyOffset()), regT2);
+    DataLabelCompact displacementLabel1 = loadPtrWithCompactAddressOffsetPatch(Address(regT2, patchGetByIdDefaultOffset), regT0); // payload
+    DataLabelCompact displacementLabel2 = loadPtrWithCompactAddressOffsetPatch(Address(regT2, patchGetByIdDefaultOffset), regT1); // tag
     
     Label putResult(this);
-    ASSERT(differenceBetween(hotPathBegin, putResult) == patchOffsetGetByIdPutResult);
     
     END_UNINTERRUPTED_SEQUENCE(sequenceGetByIdHotPath);
+
+    m_propertyAccessCompilationInfo.append(PropertyStubCompilationInfo(PropertyStubGetById, m_bytecodeOffset, hotPathBegin, structureToCompare, structureCheck, propertyStorageLoad, displacementLabel1, displacementLabel2, putResult));
 }
 
 void JIT::emitSlow_op_get_by_id(Instruction* currentInstruction, Vector<SlowCaseEntry>::iterator& iter)
@@ -459,9 +508,10 @@ void JIT::emitSlow_op_get_by_id(Instruction* currentInstruction, Vector<SlowCase
     int ident = currentInstruction[3].u.operand;
     
     compileGetByIdSlowCase(dst, base, &(m_codeBlock->identifier(ident)), iter);
+    emitValueProfilingSite();
 }
 
-void JIT::compileGetByIdSlowCase(int dst, int base, Identifier* ident, Vector<SlowCaseEntry>::iterator& iter, bool isMethodCheck)
+void JIT::compileGetByIdSlowCase(int dst, int base, Identifier* ident, Vector<SlowCaseEntry>::iterator& iter)
 {
     // As for the hot path of get_by_id, above, we ensure that we can use an architecture specific offset
     // so that we only need track one pointer into the slow case code - we track a pointer to the location
@@ -473,21 +523,16 @@ void JIT::compileGetByIdSlowCase(int dst, int base, Identifier* ident, Vector<Sl
     
     BEGIN_UNINTERRUPTED_SEQUENCE(sequenceGetByIdSlowCase);
     
-#ifndef NDEBUG
     Label coldPathBegin(this);
-#endif
-    JITStubCall stubCall(this, isMethodCheck ? cti_op_get_by_id_method_check : cti_op_get_by_id);
+    JITStubCall stubCall(this, cti_op_get_by_id);
     stubCall.addArgument(regT1, regT0);
-    stubCall.addArgument(ImmPtr(ident));
+    stubCall.addArgument(TrustedImmPtr(ident));
     Call call = stubCall.call(dst);
     
-    END_UNINTERRUPTED_SEQUENCE(sequenceGetByIdSlowCase);
-    
-    ASSERT(differenceBetween(coldPathBegin, call) == patchOffsetGetByIdSlowCaseCall);
+    END_UNINTERRUPTED_SEQUENCE_FOR_PUT(sequenceGetByIdSlowCase, dst);
     
     // Track the location of the call; this will be used to recover patch information.
-    m_propertyAccessCompilationInfo[m_propertyAccessInstructionIndex].callReturnLocation = call;
-    m_propertyAccessInstructionIndex++;
+    m_propertyAccessCompilationInfo[m_propertyAccessInstructionIndex++].slowCaseInfo(PropertyStubGetById, coldPathBegin, call);
 }
 
 void JIT::emit_op_put_by_id(Instruction* currentInstruction)
@@ -506,27 +551,20 @@ void JIT::emit_op_put_by_id(Instruction* currentInstruction)
     BEGIN_UNINTERRUPTED_SEQUENCE(sequencePutById);
     
     Label hotPathBegin(this);
-    m_propertyAccessCompilationInfo[m_propertyAccessInstructionIndex].hotPathBegin = hotPathBegin;
-    m_propertyAccessInstructionIndex++;
     
     // It is important that the following instruction plants a 32bit immediate, in order that it can be patched over.
     DataLabelPtr structureToCompare;
-    addSlowCase(branchPtrWithPatch(NotEqual, Address(regT0, OBJECT_OFFSETOF(JSCell, m_structure)), structureToCompare, ImmPtr(reinterpret_cast<void*>(patchGetByIdDefaultStructure))));
-    ASSERT(differenceBetween(hotPathBegin, structureToCompare) == patchOffsetPutByIdStructure);
+    addSlowCase(branchPtrWithPatch(NotEqual, Address(regT0, JSCell::structureOffset()), structureToCompare, TrustedImmPtr(reinterpret_cast<void*>(patchGetByIdDefaultStructure))));
     
-    // Plant a load from a bogus ofset in the object's property map; we will patch this later, if it is to be used.
-    Label externalLoad = loadPtrWithPatchToLEA(Address(regT0, OBJECT_OFFSETOF(JSObject, m_externalStorage)), regT0);
-    Label externalLoadComplete(this);
-    ASSERT(differenceBetween(hotPathBegin, externalLoad) == patchOffsetPutByIdExternalLoad);
-    ASSERT(differenceBetween(externalLoad, externalLoadComplete) == patchLengthPutByIdExternalLoad);
-    
-    DataLabel32 displacementLabel1 = storePtrWithAddressOffsetPatch(regT2, Address(regT0, patchGetByIdDefaultOffset)); // payload
-    DataLabel32 displacementLabel2 = storePtrWithAddressOffsetPatch(regT3, Address(regT0, patchGetByIdDefaultOffset)); // tag
+    ConvertibleLoadLabel propertyStorageLoad = convertibleLoadPtr(Address(regT0, JSObject::butterflyOffset()), regT1);
+    DataLabel32 displacementLabel1 = storePtrWithAddressOffsetPatch(regT2, Address(regT1, patchPutByIdDefaultOffset)); // payload
+    DataLabel32 displacementLabel2 = storePtrWithAddressOffsetPatch(regT3, Address(regT1, patchPutByIdDefaultOffset)); // tag
     
     END_UNINTERRUPTED_SEQUENCE(sequencePutById);
-    
-    ASSERT(differenceBetween(hotPathBegin, displacementLabel1) == patchOffsetPutByIdPropertyMapOffset1);
-    ASSERT(differenceBetween(hotPathBegin, displacementLabel2) == patchOffsetPutByIdPropertyMapOffset2);
+
+    emitWriteBarrier(regT0, regT2, regT1, regT2, ShouldFilterImmediates, WriteBarrierForPropertyAccess);
+
+    m_propertyAccessCompilationInfo.append(PropertyStubCompilationInfo(PropertyStubPutById, m_bytecodeOffset, hotPathBegin, structureToCompare, propertyStorageLoad, displacementLabel1, displacementLabel2));
 }
 
 void JIT::emitSlow_op_put_by_id(Instruction* currentInstruction, Vector<SlowCaseEntry>::iterator& iter)
@@ -539,80 +577,87 @@ void JIT::emitSlow_op_put_by_id(Instruction* currentInstruction, Vector<SlowCase
     linkSlowCase(iter);
     
     JITStubCall stubCall(this, direct ? cti_op_put_by_id_direct : cti_op_put_by_id);
-    stubCall.addArgument(regT1, regT0);
-    stubCall.addArgument(ImmPtr(&(m_codeBlock->identifier(ident))));
+    stubCall.addArgument(base);
+    stubCall.addArgument(TrustedImmPtr(&(m_codeBlock->identifier(ident))));
     stubCall.addArgument(regT3, regT2); 
     Call call = stubCall.call();
     
     // Track the location of the call; this will be used to recover patch information.
-    m_propertyAccessCompilationInfo[m_propertyAccessInstructionIndex].callReturnLocation = call;
-    m_propertyAccessInstructionIndex++;
+    m_propertyAccessCompilationInfo[m_propertyAccessInstructionIndex++].slowCaseInfo(PropertyStubPutById, call);
 }
 
 // Compile a store into an object's property storage.  May overwrite base.
-void JIT::compilePutDirectOffset(RegisterID base, RegisterID valueTag, RegisterID valuePayload, Structure* structure, size_t cachedOffset)
+void JIT::compilePutDirectOffset(RegisterID base, RegisterID valueTag, RegisterID valuePayload, PropertyOffset cachedOffset)
 {
-    int offset = cachedOffset;
-    if (structure->isUsingInlineStorage())
-        offset += OBJECT_OFFSETOF(JSObject, m_inlineStorage) /  sizeof(Register);
-    else
-        loadPtr(Address(base, OBJECT_OFFSETOF(JSObject, m_externalStorage)), base);
-    emitStore(offset, valueTag, valuePayload, base);
+    if (isOutOfLineOffset(cachedOffset))
+        loadPtr(Address(base, JSObject::butterflyOffset()), base);
+    emitStore(indexRelativeToBase(cachedOffset), valueTag, valuePayload, base);
 }
 
 // Compile a load from an object's property storage.  May overwrite base.
-void JIT::compileGetDirectOffset(RegisterID base, RegisterID resultTag, RegisterID resultPayload, Structure* structure, size_t cachedOffset)
+void JIT::compileGetDirectOffset(RegisterID base, RegisterID resultTag, RegisterID resultPayload, PropertyOffset cachedOffset)
 {
-    int offset = cachedOffset;
-    if (structure->isUsingInlineStorage())
-        offset += OBJECT_OFFSETOF(JSObject, m_inlineStorage) / sizeof(Register);
-    else
-        loadPtr(Address(base, OBJECT_OFFSETOF(JSObject, m_externalStorage)), base);
-    emitLoad(offset, resultTag, resultPayload, base);
-}
-
-void JIT::compileGetDirectOffset(JSObject* base, RegisterID temp, RegisterID resultTag, RegisterID resultPayload, size_t cachedOffset)
-{
-    if (base->isUsingInlineStorage()) {
-        load32(reinterpret_cast<char*>(&base->m_inlineStorage[cachedOffset]), resultPayload);
-        load32(reinterpret_cast<char*>(&base->m_inlineStorage[cachedOffset]) + 4, resultTag);
+    if (isInlineOffset(cachedOffset)) {
+        emitLoad(indexRelativeToBase(cachedOffset), resultTag, resultPayload, base);
         return;
     }
     
-    size_t offset = cachedOffset * sizeof(JSValue);
-    
-    PropertyStorage* protoPropertyStorage = &base->m_externalStorage;
-    loadPtr(static_cast<void*>(protoPropertyStorage), temp);
-    load32(Address(temp, offset), resultPayload);
-    load32(Address(temp, offset + 4), resultTag);
+    RegisterID temp = resultPayload;
+    loadPtr(Address(base, JSObject::butterflyOffset()), temp);
+    emitLoad(indexRelativeToBase(cachedOffset), resultTag, resultPayload, temp);
 }
 
-void JIT::testPrototype(Structure* structure, JumpList& failureCases)
+void JIT::compileGetDirectOffset(JSObject* base, RegisterID resultTag, RegisterID resultPayload, PropertyOffset cachedOffset)
 {
-    if (structure->m_prototype.isNull())
+    if (isInlineOffset(cachedOffset)) {
+        move(TrustedImmPtr(base->locationForOffset(cachedOffset)), resultTag);
+        load32(Address(resultTag, OBJECT_OFFSETOF(JSValue, u.asBits.payload)), resultPayload);
+        load32(Address(resultTag, OBJECT_OFFSETOF(JSValue, u.asBits.tag)), resultTag);
         return;
+    }
     
-    failureCases.append(branchPtr(NotEqual, AbsoluteAddress(&asCell(structure->m_prototype)->m_structure), ImmPtr(asCell(structure->m_prototype)->m_structure)));
+    loadPtr(base->butterflyAddress(), resultTag);
+    load32(Address(resultTag, offsetInButterfly(cachedOffset) * sizeof(WriteBarrier<Unknown>) + OBJECT_OFFSETOF(JSValue, u.asBits.payload)), resultPayload);
+    load32(Address(resultTag, offsetInButterfly(cachedOffset) * sizeof(WriteBarrier<Unknown>) + OBJECT_OFFSETOF(JSValue, u.asBits.tag)), resultTag);
 }
 
-void JIT::privateCompilePutByIdTransition(StructureStubInfo* stubInfo, Structure* oldStructure, Structure* newStructure, size_t cachedOffset, StructureChain* chain, ReturnAddressPtr returnAddress, bool direct)
+void JIT::privateCompilePutByIdTransition(StructureStubInfo* stubInfo, Structure* oldStructure, Structure* newStructure, PropertyOffset cachedOffset, StructureChain* chain, ReturnAddressPtr returnAddress, bool direct)
 {
-    // It is assumed that regT0 contains the basePayload and regT1 contains the baseTag.  The value can be found on the stack.
-    
+    // The code below assumes that regT0 contains the basePayload and regT1 contains the baseTag. Restore them from the stack.
+#if CPU(MIPS) || CPU(SH4) || CPU(ARM)
+    // For MIPS, we don't add sizeof(void*) to the stack offset.
+    load32(Address(stackPointerRegister, OBJECT_OFFSETOF(JITStackFrame, args[0]) + OBJECT_OFFSETOF(JSValue, u.asBits.payload)), regT0);
+    // For MIPS, we don't add sizeof(void*) to the stack offset.
+    load32(Address(stackPointerRegister, OBJECT_OFFSETOF(JITStackFrame, args[0]) + OBJECT_OFFSETOF(JSValue, u.asBits.tag)), regT1);
+#else
+    load32(Address(stackPointerRegister, OBJECT_OFFSETOF(JITStackFrame, args[0]) + sizeof(void*) + OBJECT_OFFSETOF(JSValue, u.asBits.payload)), regT0);
+    load32(Address(stackPointerRegister, OBJECT_OFFSETOF(JITStackFrame, args[0]) + sizeof(void*) + OBJECT_OFFSETOF(JSValue, u.asBits.tag)), regT1);
+#endif
+
     JumpList failureCases;
-    failureCases.append(branch32(NotEqual, regT1, Imm32(JSValue::CellTag)));
-    failureCases.append(branchPtr(NotEqual, Address(regT0, OBJECT_OFFSETOF(JSCell, m_structure)), ImmPtr(oldStructure)));
-    testPrototype(oldStructure, failureCases);
+    failureCases.append(branch32(NotEqual, regT1, TrustedImm32(JSValue::CellTag)));
+    failureCases.append(branchPtr(NotEqual, Address(regT0, JSCell::structureOffset()), TrustedImmPtr(oldStructure)));
+    testPrototype(oldStructure->storedPrototype(), failureCases, stubInfo);
     
     if (!direct) {
         // Verify that nothing in the prototype chain has a setter for this property. 
-        for (RefPtr<Structure>* it = chain->head(); *it; ++it)
-            testPrototype(it->get(), failureCases);
+        for (WriteBarrier<Structure>* it = chain->head(); *it; ++it)
+            testPrototype((*it)->storedPrototype(), failureCases, stubInfo);
     }
 
+    // If we succeed in all of our checks, and the code was optimizable, then make sure we
+    // decrement the rare case counter.
+#if ENABLE(VALUE_PROFILER)
+    if (m_codeBlock->canCompileWithDFG() >= DFG::MayInline) {
+        sub32(
+            TrustedImm32(1),
+            AbsoluteAddress(&m_codeBlock->rareCaseProfileForBytecodeOffset(stubInfo->bytecodeIndex)->m_counter));
+    }
+#endif
+    
     // Reallocate property storage if needed.
     Call callTarget;
-    bool willNeedStorageRealloc = oldStructure->propertyStorageCapacity() != newStructure->propertyStorageCapacity();
+    bool willNeedStorageRealloc = oldStructure->outOfLineCapacity() != newStructure->outOfLineCapacity();
     if (willNeedStorageRealloc) {
         // This trampoline was called to like a JIT stub; before we can can call again we need to
         // remove the return address from the stack, to prevent the stack from becoming misaligned.
@@ -622,22 +667,35 @@ void JIT::privateCompilePutByIdTransition(StructureStubInfo* stubInfo, Structure
         stubCall.skipArgument(); // base
         stubCall.skipArgument(); // ident
         stubCall.skipArgument(); // value
-        stubCall.addArgument(Imm32(oldStructure->propertyStorageCapacity()));
-        stubCall.addArgument(Imm32(newStructure->propertyStorageCapacity()));
+        stubCall.addArgument(TrustedImm32(oldStructure->outOfLineCapacity()));
+        stubCall.addArgument(TrustedImmPtr(newStructure));
         stubCall.call(regT0);
-        
+
         restoreReturnAddressBeforeReturn(regT3);
+
+#if CPU(MIPS) || CPU(SH4) || CPU(ARM)
+        // For MIPS, we don't add sizeof(void*) to the stack offset.
+        load32(Address(stackPointerRegister, OBJECT_OFFSETOF(JITStackFrame, args[0]) + OBJECT_OFFSETOF(JSValue, u.asBits.payload)), regT0);
+        // For MIPS, we don't add sizeof(void*) to the stack offset.
+        load32(Address(stackPointerRegister, OBJECT_OFFSETOF(JITStackFrame, args[0]) + OBJECT_OFFSETOF(JSValue, u.asBits.tag)), regT1);
+#else
+        load32(Address(stackPointerRegister, OBJECT_OFFSETOF(JITStackFrame, args[0]) + sizeof(void*) + OBJECT_OFFSETOF(JSValue, u.asBits.payload)), regT0);
+        load32(Address(stackPointerRegister, OBJECT_OFFSETOF(JITStackFrame, args[0]) + sizeof(void*) + OBJECT_OFFSETOF(JSValue, u.asBits.tag)), regT1);
+#endif
     }
-    
-    sub32(Imm32(1), AbsoluteAddress(oldStructure->addressOfCount()));
-    add32(Imm32(1), AbsoluteAddress(newStructure->addressOfCount()));
-    storePtr(ImmPtr(newStructure), Address(regT0, OBJECT_OFFSETOF(JSCell, m_structure)));
-    
-    load32(Address(stackPointerRegister, OBJECT_OFFSETOF(struct JITStackFrame, args[2]) + sizeof(void*)), regT3);
-    load32(Address(stackPointerRegister, OBJECT_OFFSETOF(struct JITStackFrame, args[2]) + sizeof(void*) + 4), regT2);
-    
-    // Write the value
-    compilePutDirectOffset(regT0, regT2, regT3, newStructure, cachedOffset);
+
+    emitWriteBarrier(regT0, regT1, regT1, regT3, UnconditionalWriteBarrier, WriteBarrierForPropertyAccess);
+
+    storePtr(TrustedImmPtr(newStructure), Address(regT0, JSCell::structureOffset()));
+#if CPU(MIPS) || CPU(SH4) || CPU(ARM)
+    // For MIPS, we don't add sizeof(void*) to the stack offset.
+    load32(Address(stackPointerRegister, OBJECT_OFFSETOF(JITStackFrame, args[2]) + OBJECT_OFFSETOF(JSValue, u.asBits.payload)), regT3);
+    load32(Address(stackPointerRegister, OBJECT_OFFSETOF(JITStackFrame, args[2]) + OBJECT_OFFSETOF(JSValue, u.asBits.tag)), regT2);
+#else
+    load32(Address(stackPointerRegister, OBJECT_OFFSETOF(JITStackFrame, args[2]) + sizeof(void*) + OBJECT_OFFSETOF(JSValue, u.asBits.payload)), regT3);
+    load32(Address(stackPointerRegister, OBJECT_OFFSETOF(JITStackFrame, args[2]) + sizeof(void*) + OBJECT_OFFSETOF(JSValue, u.asBits.tag)), regT2);
+#endif
+    compilePutDirectOffset(regT0, regT2, regT3, cachedOffset);
     
     ret();
     
@@ -646,7 +704,7 @@ void JIT::privateCompilePutByIdTransition(StructureStubInfo* stubInfo, Structure
     restoreArgumentReferenceForTrampoline();
     Call failureCall = tailRecursiveCall();
     
-    LinkBuffer patchBuffer(this, m_codeBlock->executablePool(), 0);
+    LinkBuffer patchBuffer(*m_vm, this, m_codeBlock);
     
     patchBuffer.link(failureCall, FunctionPtr(direct ? cti_op_put_by_id_direct_fail : cti_op_put_by_id_fail));
     
@@ -655,13 +713,20 @@ void JIT::privateCompilePutByIdTransition(StructureStubInfo* stubInfo, Structure
         patchBuffer.link(m_calls[0].from, FunctionPtr(cti_op_put_by_id_transition_realloc));
     }
     
-    CodeLocationLabel entryLabel = patchBuffer.finalizeCodeAddendum();
-    stubInfo->stubRoutine = entryLabel;
+    stubInfo->stubRoutine = createJITStubRoutine(
+        FINALIZE_CODE(
+            patchBuffer,
+            ("Baseline put_by_id transition stub for %s, return point %p",
+                toCString(*m_codeBlock).data(), returnAddress.value())),
+        *m_vm,
+        m_codeBlock->ownerExecutable(),
+        willNeedStorageRealloc,
+        newStructure);
     RepatchBuffer repatchBuffer(m_codeBlock);
-    repatchBuffer.relinkCallerToTrampoline(returnAddress, entryLabel);
+    repatchBuffer.relinkCallerToTrampoline(returnAddress, CodeLocationLabel(stubInfo->stubRoutine->code().code()));
 }
 
-void JIT::patchGetByIdSelf(CodeBlock* codeBlock, StructureStubInfo* stubInfo, Structure* structure, size_t cachedOffset, ReturnAddressPtr returnAddress)
+void JIT::patchGetByIdSelf(CodeBlock* codeBlock, StructureStubInfo* stubInfo, Structure* structure, PropertyOffset cachedOffset, ReturnAddressPtr returnAddress)
 {
     RepatchBuffer repatchBuffer(codeBlock);
     
@@ -669,40 +734,14 @@ void JIT::patchGetByIdSelf(CodeBlock* codeBlock, StructureStubInfo* stubInfo, St
     // Should probably go to JITStubs::cti_op_get_by_id_fail, but that doesn't do anything interesting right now.
     repatchBuffer.relinkCallerToFunction(returnAddress, FunctionPtr(cti_op_get_by_id_self_fail));
     
-    int offset = sizeof(JSValue) * cachedOffset;
-    
-    // If we're patching to use inline storage, convert the initial load to a lea; this avoids the extra load
-    // and makes the subsequent load's offset automatically correct
-    if (structure->isUsingInlineStorage())
-        repatchBuffer.repatchLoadPtrToLEA(stubInfo->hotPathBegin.instructionAtOffset(patchOffsetGetByIdExternalLoad));
-    
     // Patch the offset into the propoerty map to load from, then patch the Structure to look for.
-    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabelPtrAtOffset(patchOffsetGetByIdStructure), structure);
-    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabel32AtOffset(patchOffsetGetByIdPropertyMapOffset1), offset); // payload
-    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabel32AtOffset(patchOffsetGetByIdPropertyMapOffset2), offset + 4); // tag
+    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabelPtrAtOffset(stubInfo->patch.baseline.u.get.structureToCompare), structure);
+    repatchBuffer.setLoadInstructionIsActive(stubInfo->hotPathBegin.convertibleLoadAtOffset(stubInfo->patch.baseline.u.get.propertyStorageLoad), isOutOfLineOffset(cachedOffset));
+    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabelCompactAtOffset(stubInfo->patch.baseline.u.get.displacementLabel1), offsetRelativeToPatchedStorage(cachedOffset) + OBJECT_OFFSETOF(JSValue, u.asBits.payload)); // payload
+    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabelCompactAtOffset(stubInfo->patch.baseline.u.get.displacementLabel2), offsetRelativeToPatchedStorage(cachedOffset) + OBJECT_OFFSETOF(JSValue, u.asBits.tag)); // tag
 }
 
-void JIT::patchMethodCallProto(CodeBlock* codeBlock, MethodCallLinkInfo& methodCallLinkInfo, JSFunction* callee, Structure* structure, JSObject* proto, ReturnAddressPtr returnAddress)
-{
-    RepatchBuffer repatchBuffer(codeBlock);
-    
-    ASSERT(!methodCallLinkInfo.cachedStructure);
-    methodCallLinkInfo.cachedStructure = structure;
-    structure->ref();
-    
-    Structure* prototypeStructure = proto->structure();
-    methodCallLinkInfo.cachedPrototypeStructure = prototypeStructure;
-    prototypeStructure->ref();
-    
-    repatchBuffer.repatch(methodCallLinkInfo.structureLabel, structure);
-    repatchBuffer.repatch(methodCallLinkInfo.structureLabel.dataLabelPtrAtOffset(patchOffsetMethodCheckProtoObj), proto);
-    repatchBuffer.repatch(methodCallLinkInfo.structureLabel.dataLabelPtrAtOffset(patchOffsetMethodCheckProtoStruct), prototypeStructure);
-    repatchBuffer.repatch(methodCallLinkInfo.structureLabel.dataLabelPtrAtOffset(patchOffsetMethodCheckPutFunction), callee);
-    
-    repatchBuffer.relinkCallerToFunction(returnAddress, FunctionPtr(cti_op_get_by_id));
-}
-
-void JIT::patchPutByIdReplace(CodeBlock* codeBlock, StructureStubInfo* stubInfo, Structure* structure, size_t cachedOffset, ReturnAddressPtr returnAddress, bool direct)
+void JIT::patchPutByIdReplace(CodeBlock* codeBlock, StructureStubInfo* stubInfo, Structure* structure, PropertyOffset cachedOffset, ReturnAddressPtr returnAddress, bool direct)
 {
     RepatchBuffer repatchBuffer(codeBlock);
     
@@ -710,17 +749,11 @@ void JIT::patchPutByIdReplace(CodeBlock* codeBlock, StructureStubInfo* stubInfo,
     // Should probably go to cti_op_put_by_id_fail, but that doesn't do anything interesting right now.
     repatchBuffer.relinkCallerToFunction(returnAddress, FunctionPtr(direct ? cti_op_put_by_id_direct_generic : cti_op_put_by_id_generic));
     
-    int offset = sizeof(JSValue) * cachedOffset;
-    
-    // If we're patching to use inline storage, convert the initial load to a lea; this avoids the extra load
-    // and makes the subsequent load's offset automatically correct
-    if (structure->isUsingInlineStorage())
-        repatchBuffer.repatchLoadPtrToLEA(stubInfo->hotPathBegin.instructionAtOffset(patchOffsetPutByIdExternalLoad));
-    
     // Patch the offset into the propoerty map to load from, then patch the Structure to look for.
-    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabelPtrAtOffset(patchOffsetPutByIdStructure), structure);
-    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabel32AtOffset(patchOffsetPutByIdPropertyMapOffset1), offset); // payload
-    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabel32AtOffset(patchOffsetPutByIdPropertyMapOffset2), offset + 4); // tag
+    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabelPtrAtOffset(stubInfo->patch.baseline.u.put.structureToCompare), structure);
+    repatchBuffer.setLoadInstructionIsActive(stubInfo->hotPathBegin.convertibleLoadAtOffset(stubInfo->patch.baseline.u.put.propertyStorageLoad), isOutOfLineOffset(cachedOffset));
+    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabel32AtOffset(stubInfo->patch.baseline.u.put.displacementLabel1), offsetRelativeToPatchedStorage(cachedOffset) + OBJECT_OFFSETOF(JSValue, u.asBits.payload)); // payload
+    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabel32AtOffset(stubInfo->patch.baseline.u.put.displacementLabel2), offsetRelativeToPatchedStorage(cachedOffset) + OBJECT_OFFSETOF(JSValue, u.asBits.tag)); // tag
 }
 
 void JIT::privateCompilePatchGetArrayLength(ReturnAddressPtr returnAddress)
@@ -730,41 +763,47 @@ void JIT::privateCompilePatchGetArrayLength(ReturnAddressPtr returnAddress)
     // regT0 holds a JSCell*
     
     // Check for array
-    Jump failureCases1 = branchPtr(NotEqual, Address(regT0), ImmPtr(m_globalData->jsArrayVPtr));
+    loadPtr(Address(regT0, JSCell::structureOffset()), regT2);
+    Jump failureCases1 = branchTest32(Zero, regT2, TrustedImm32(IsArray));
+    Jump failureCases2 = branchTest32(Zero, regT2, TrustedImm32(IndexingShapeMask));
     
     // Checks out okay! - get the length from the storage
-    loadPtr(Address(regT0, OBJECT_OFFSETOF(JSArray, m_storage)), regT2);
-    load32(Address(regT2, OBJECT_OFFSETOF(ArrayStorage, m_length)), regT2);
+    loadPtr(Address(regT0, JSArray::butterflyOffset()), regT2);
+    load32(Address(regT2, ArrayStorage::lengthOffset()), regT2);
     
-    Jump failureCases2 = branch32(Above, regT2, Imm32(INT_MAX));
+    Jump failureCases3 = branch32(Above, regT2, TrustedImm32(INT_MAX));
     move(regT2, regT0);
-    move(Imm32(JSValue::Int32Tag), regT1);
+    move(TrustedImm32(JSValue::Int32Tag), regT1);
     Jump success = jump();
     
-    LinkBuffer patchBuffer(this, m_codeBlock->executablePool(), 0);
+    LinkBuffer patchBuffer(*m_vm, this, m_codeBlock);
     
     // Use the patch information to link the failure cases back to the original slow case routine.
-    CodeLocationLabel slowCaseBegin = stubInfo->callReturnLocation.labelAtOffset(-patchOffsetGetByIdSlowCaseCall);
+    CodeLocationLabel slowCaseBegin = stubInfo->callReturnLocation.labelAtOffset(-stubInfo->patch.baseline.u.get.coldPathBegin);
     patchBuffer.link(failureCases1, slowCaseBegin);
     patchBuffer.link(failureCases2, slowCaseBegin);
+    patchBuffer.link(failureCases3, slowCaseBegin);
     
     // On success return back to the hot patch code, at a point it will perform the store to dest for us.
-    patchBuffer.link(success, stubInfo->hotPathBegin.labelAtOffset(patchOffsetGetByIdPutResult));
+    patchBuffer.link(success, stubInfo->hotPathBegin.labelAtOffset(stubInfo->patch.baseline.u.get.putResult));
     
     // Track the stub we have created so that it will be deleted later.
-    CodeLocationLabel entryLabel = patchBuffer.finalizeCodeAddendum();
-    stubInfo->stubRoutine = entryLabel;
+    stubInfo->stubRoutine = FINALIZE_CODE_FOR_STUB(
+        patchBuffer,
+        ("Baseline get_by_id array length stub for %s, return point %p",
+            toCString(*m_codeBlock).data(), stubInfo->hotPathBegin.labelAtOffset(
+                stubInfo->patch.baseline.u.get.putResult).executableAddress()));
     
     // Finally patch the jump to slow case back in the hot path to jump here instead.
-    CodeLocationJump jumpLocation = stubInfo->hotPathBegin.jumpAtOffset(patchOffsetGetByIdBranchToSlowCase);
+    CodeLocationJump jumpLocation = stubInfo->hotPathBegin.jumpAtOffset(stubInfo->patch.baseline.u.get.structureCheck);
     RepatchBuffer repatchBuffer(m_codeBlock);
-    repatchBuffer.relink(jumpLocation, entryLabel);
+    repatchBuffer.relink(jumpLocation, CodeLocationLabel(stubInfo->stubRoutine->code().code()));
     
     // We don't want to patch more than once - in future go to cti_op_put_by_id_generic.
     repatchBuffer.relinkCallerToFunction(returnAddress, FunctionPtr(cti_op_get_by_id_array_fail));
 }
 
-void JIT::privateCompileGetByIdProto(StructureStubInfo* stubInfo, Structure* structure, Structure* prototypeStructure, const Identifier& ident, const PropertySlot& slot, size_t cachedOffset, ReturnAddressPtr returnAddress, CallFrame* callFrame)
+void JIT::privateCompileGetByIdProto(StructureStubInfo* stubInfo, Structure* structure, Structure* prototypeStructure, const Identifier& ident, const PropertySlot& slot, PropertyOffset cachedOffset, ReturnAddressPtr returnAddress, CallFrame* callFrame)
 {
     // regT0 holds a JSCell*
     
@@ -775,45 +814,41 @@ void JIT::privateCompileGetByIdProto(StructureStubInfo* stubInfo, Structure* str
     Jump failureCases1 = checkStructure(regT0, structure);
     
     // Check the prototype object's Structure had not changed.
-    Structure** prototypeStructureAddress = &(protoObject->m_structure);
-#if CPU(X86_64)
-    move(ImmPtr(prototypeStructure), regT3);
-    Jump failureCases2 = branchPtr(NotEqual, AbsoluteAddress(prototypeStructureAddress), regT3);
-#else
-    Jump failureCases2 = branchPtr(NotEqual, AbsoluteAddress(prototypeStructureAddress), ImmPtr(prototypeStructure));
-#endif
+    Jump failureCases2 = addStructureTransitionCheck(protoObject, prototypeStructure, stubInfo, regT3);
+
     bool needsStubLink = false;
     // Checks out okay!
     if (slot.cachedPropertyType() == PropertySlot::Getter) {
         needsStubLink = true;
-        compileGetDirectOffset(protoObject, regT2, regT2, regT1, cachedOffset);
+        compileGetDirectOffset(protoObject, regT2, regT1, cachedOffset);
         JITStubCall stubCall(this, cti_op_get_by_id_getter_stub);
         stubCall.addArgument(regT1);
         stubCall.addArgument(regT0);
-        stubCall.addArgument(ImmPtr(stubInfo->callReturnLocation.executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(stubInfo->callReturnLocation.executableAddress()));
         stubCall.call();
     } else if (slot.cachedPropertyType() == PropertySlot::Custom) {
         needsStubLink = true;
         JITStubCall stubCall(this, cti_op_get_by_id_custom_stub);
-        stubCall.addArgument(ImmPtr(protoObject));
-        stubCall.addArgument(ImmPtr(FunctionPtr(slot.customGetter()).executableAddress()));
-        stubCall.addArgument(ImmPtr(const_cast<Identifier*>(&ident)));
-        stubCall.addArgument(ImmPtr(stubInfo->callReturnLocation.executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(protoObject));
+        stubCall.addArgument(TrustedImmPtr(FunctionPtr(slot.customGetter()).executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(const_cast<Identifier*>(&ident)));
+        stubCall.addArgument(TrustedImmPtr(stubInfo->callReturnLocation.executableAddress()));
         stubCall.call();
     } else
-        compileGetDirectOffset(protoObject, regT2, regT1, regT0, cachedOffset);
+        compileGetDirectOffset(protoObject, regT1, regT0, cachedOffset);
     
     Jump success = jump();
     
-    LinkBuffer patchBuffer(this, m_codeBlock->executablePool(), 0);
+    LinkBuffer patchBuffer(*m_vm, this, m_codeBlock);
     
     // Use the patch information to link the failure cases back to the original slow case routine.
-    CodeLocationLabel slowCaseBegin = stubInfo->callReturnLocation.labelAtOffset(-patchOffsetGetByIdSlowCaseCall);
+    CodeLocationLabel slowCaseBegin = stubInfo->callReturnLocation.labelAtOffset(-stubInfo->patch.baseline.u.get.coldPathBegin);
     patchBuffer.link(failureCases1, slowCaseBegin);
-    patchBuffer.link(failureCases2, slowCaseBegin);
+    if (failureCases2.isSet())
+        patchBuffer.link(failureCases2, slowCaseBegin);
     
     // On success return back to the hot patch code, at a point it will perform the store to dest for us.
-    patchBuffer.link(success, stubInfo->hotPathBegin.labelAtOffset(patchOffsetGetByIdPutResult));
+    patchBuffer.link(success, stubInfo->hotPathBegin.labelAtOffset(stubInfo->patch.baseline.u.get.putResult));
 
     if (needsStubLink) {
         for (Vector<CallRecord>::iterator iter = m_calls.begin(); iter != m_calls.end(); ++iter) {
@@ -823,50 +858,56 @@ void JIT::privateCompileGetByIdProto(StructureStubInfo* stubInfo, Structure* str
     }
 
     // Track the stub we have created so that it will be deleted later.
-    CodeLocationLabel entryLabel = patchBuffer.finalizeCodeAddendum();
-    stubInfo->stubRoutine = entryLabel;
+    stubInfo->stubRoutine = createJITStubRoutine(
+        FINALIZE_CODE(
+            patchBuffer,
+            ("Baseline get_by_id proto stub for %s, return point %p",
+                toCString(*m_codeBlock).data(), stubInfo->hotPathBegin.labelAtOffset(
+                    stubInfo->patch.baseline.u.get.putResult).executableAddress())),
+        *m_vm,
+        m_codeBlock->ownerExecutable(),
+        needsStubLink);
     
     // Finally patch the jump to slow case back in the hot path to jump here instead.
-    CodeLocationJump jumpLocation = stubInfo->hotPathBegin.jumpAtOffset(patchOffsetGetByIdBranchToSlowCase);
+    CodeLocationJump jumpLocation = stubInfo->hotPathBegin.jumpAtOffset(stubInfo->patch.baseline.u.get.structureCheck);
     RepatchBuffer repatchBuffer(m_codeBlock);
-    repatchBuffer.relink(jumpLocation, entryLabel);
+    repatchBuffer.relink(jumpLocation, CodeLocationLabel(stubInfo->stubRoutine->code().code()));
     
     // We don't want to patch more than once - in future go to cti_op_put_by_id_generic.
     repatchBuffer.relinkCallerToFunction(returnAddress, FunctionPtr(cti_op_get_by_id_proto_list));
 }
 
 
-void JIT::privateCompileGetByIdSelfList(StructureStubInfo* stubInfo, PolymorphicAccessStructureList* polymorphicStructures, int currentIndex, Structure* structure, const Identifier& ident, const PropertySlot& slot, size_t cachedOffset)
+void JIT::privateCompileGetByIdSelfList(StructureStubInfo* stubInfo, PolymorphicAccessStructureList* polymorphicStructures, int currentIndex, Structure* structure, const Identifier& ident, const PropertySlot& slot, PropertyOffset cachedOffset)
 {
     // regT0 holds a JSCell*
     Jump failureCase = checkStructure(regT0, structure);
     bool needsStubLink = false;
+    bool isDirect = false;
     if (slot.cachedPropertyType() == PropertySlot::Getter) {
         needsStubLink = true;
-        if (!structure->isUsingInlineStorage()) {
-            move(regT0, regT1);
-            compileGetDirectOffset(regT1, regT2, regT1, structure, cachedOffset);
-        } else
-            compileGetDirectOffset(regT0, regT2, regT1, structure, cachedOffset);
+        compileGetDirectOffset(regT0, regT2, regT1, cachedOffset);
         JITStubCall stubCall(this, cti_op_get_by_id_getter_stub);
         stubCall.addArgument(regT1);
         stubCall.addArgument(regT0);
-        stubCall.addArgument(ImmPtr(stubInfo->callReturnLocation.executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(stubInfo->callReturnLocation.executableAddress()));
         stubCall.call();
     } else if (slot.cachedPropertyType() == PropertySlot::Custom) {
         needsStubLink = true;
         JITStubCall stubCall(this, cti_op_get_by_id_custom_stub);
         stubCall.addArgument(regT0);
-        stubCall.addArgument(ImmPtr(FunctionPtr(slot.customGetter()).executableAddress()));
-        stubCall.addArgument(ImmPtr(const_cast<Identifier*>(&ident)));
-        stubCall.addArgument(ImmPtr(stubInfo->callReturnLocation.executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(FunctionPtr(slot.customGetter()).executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(const_cast<Identifier*>(&ident)));
+        stubCall.addArgument(TrustedImmPtr(stubInfo->callReturnLocation.executableAddress()));
         stubCall.call();
-    } else
-        compileGetDirectOffset(regT0, regT1, regT0, structure, cachedOffset);
+    } else {
+        isDirect = true;
+        compileGetDirectOffset(regT0, regT1, regT0, cachedOffset);
+    }
 
     Jump success = jump();
     
-    LinkBuffer patchBuffer(this, m_codeBlock->executablePool(), 0);
+    LinkBuffer patchBuffer(*m_vm, this, m_codeBlock);
     if (needsStubLink) {
         for (Vector<CallRecord>::iterator iter = m_calls.begin(); iter != m_calls.end(); ++iter) {
             if (iter->to)
@@ -874,27 +915,34 @@ void JIT::privateCompileGetByIdSelfList(StructureStubInfo* stubInfo, Polymorphic
         }
     }    
     // Use the patch information to link the failure cases back to the original slow case routine.
-    CodeLocationLabel lastProtoBegin = polymorphicStructures->list[currentIndex - 1].stubRoutine;
+    CodeLocationLabel lastProtoBegin = CodeLocationLabel(JITStubRoutine::asCodePtr(polymorphicStructures->list[currentIndex - 1].stubRoutine));
     if (!lastProtoBegin)
-        lastProtoBegin = stubInfo->callReturnLocation.labelAtOffset(-patchOffsetGetByIdSlowCaseCall);
+        lastProtoBegin = stubInfo->callReturnLocation.labelAtOffset(-stubInfo->patch.baseline.u.get.coldPathBegin);
     
     patchBuffer.link(failureCase, lastProtoBegin);
     
     // On success return back to the hot patch code, at a point it will perform the store to dest for us.
-    patchBuffer.link(success, stubInfo->hotPathBegin.labelAtOffset(patchOffsetGetByIdPutResult));
+    patchBuffer.link(success, stubInfo->hotPathBegin.labelAtOffset(stubInfo->patch.baseline.u.get.putResult));
 
-    CodeLocationLabel entryLabel = patchBuffer.finalizeCodeAddendum();
-    
-    structure->ref();
-    polymorphicStructures->list[currentIndex].set(entryLabel, structure);
+    RefPtr<JITStubRoutine> stubRoutine = createJITStubRoutine(
+        FINALIZE_CODE(
+            patchBuffer,
+            ("Baseline get_by_id self list stub for %s, return point %p",
+                toCString(*m_codeBlock).data(), stubInfo->hotPathBegin.labelAtOffset(
+                    stubInfo->patch.baseline.u.get.putResult).executableAddress())),
+        *m_vm,
+        m_codeBlock->ownerExecutable(),
+        needsStubLink);
+
+    polymorphicStructures->list[currentIndex].set(*m_vm, m_codeBlock->ownerExecutable(), stubRoutine, structure, isDirect);
     
     // Finally patch the jump to slow case back in the hot path to jump here instead.
-    CodeLocationJump jumpLocation = stubInfo->hotPathBegin.jumpAtOffset(patchOffsetGetByIdBranchToSlowCase);
+    CodeLocationJump jumpLocation = stubInfo->hotPathBegin.jumpAtOffset(stubInfo->patch.baseline.u.get.structureCheck);
     RepatchBuffer repatchBuffer(m_codeBlock);
-    repatchBuffer.relink(jumpLocation, entryLabel);
+    repatchBuffer.relink(jumpLocation, CodeLocationLabel(stubRoutine->code().code()));
 }
 
-void JIT::privateCompileGetByIdProtoList(StructureStubInfo* stubInfo, PolymorphicAccessStructureList* prototypeStructures, int currentIndex, Structure* structure, Structure* prototypeStructure, const Identifier& ident, const PropertySlot& slot, size_t cachedOffset, CallFrame* callFrame)
+void JIT::privateCompileGetByIdProtoList(StructureStubInfo* stubInfo, PolymorphicAccessStructureList* prototypeStructures, int currentIndex, Structure* structure, Structure* prototypeStructure, const Identifier& ident, const PropertySlot& slot, PropertyOffset cachedOffset, CallFrame* callFrame)
 {
     // regT0 holds a JSCell*
     
@@ -906,37 +954,34 @@ void JIT::privateCompileGetByIdProtoList(StructureStubInfo* stubInfo, Polymorphi
     Jump failureCases1 = checkStructure(regT0, structure);
     
     // Check the prototype object's Structure had not changed.
-    Structure** prototypeStructureAddress = &(protoObject->m_structure);
-#if CPU(X86_64)
-    move(ImmPtr(prototypeStructure), regT3);
-    Jump failureCases2 = branchPtr(NotEqual, AbsoluteAddress(prototypeStructureAddress), regT3);
-#else
-    Jump failureCases2 = branchPtr(NotEqual, AbsoluteAddress(prototypeStructureAddress), ImmPtr(prototypeStructure));
-#endif
+    Jump failureCases2 = addStructureTransitionCheck(protoObject, prototypeStructure, stubInfo, regT3);
     
     bool needsStubLink = false;
+    bool isDirect = false;
     if (slot.cachedPropertyType() == PropertySlot::Getter) {
         needsStubLink = true;
-        compileGetDirectOffset(protoObject, regT2, regT2, regT1, cachedOffset);
+        compileGetDirectOffset(protoObject, regT2, regT1, cachedOffset);
         JITStubCall stubCall(this, cti_op_get_by_id_getter_stub);
         stubCall.addArgument(regT1);
         stubCall.addArgument(regT0);
-        stubCall.addArgument(ImmPtr(stubInfo->callReturnLocation.executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(stubInfo->callReturnLocation.executableAddress()));
         stubCall.call();
     } else if (slot.cachedPropertyType() == PropertySlot::Custom) {
         needsStubLink = true;
         JITStubCall stubCall(this, cti_op_get_by_id_custom_stub);
-        stubCall.addArgument(ImmPtr(protoObject));
-        stubCall.addArgument(ImmPtr(FunctionPtr(slot.customGetter()).executableAddress()));
-        stubCall.addArgument(ImmPtr(const_cast<Identifier*>(&ident)));
-        stubCall.addArgument(ImmPtr(stubInfo->callReturnLocation.executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(protoObject));
+        stubCall.addArgument(TrustedImmPtr(FunctionPtr(slot.customGetter()).executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(const_cast<Identifier*>(&ident)));
+        stubCall.addArgument(TrustedImmPtr(stubInfo->callReturnLocation.executableAddress()));
         stubCall.call();
-    } else
-        compileGetDirectOffset(protoObject, regT2, regT1, regT0, cachedOffset);
+    } else {
+        isDirect = true;
+        compileGetDirectOffset(protoObject, regT1, regT0, cachedOffset);
+    }
     
     Jump success = jump();
     
-    LinkBuffer patchBuffer(this, m_codeBlock->executablePool(), 0);
+    LinkBuffer patchBuffer(*m_vm, this, m_codeBlock);
     if (needsStubLink) {
         for (Vector<CallRecord>::iterator iter = m_calls.begin(); iter != m_calls.end(); ++iter) {
             if (iter->to)
@@ -944,26 +989,33 @@ void JIT::privateCompileGetByIdProtoList(StructureStubInfo* stubInfo, Polymorphi
         }
     }
     // Use the patch information to link the failure cases back to the original slow case routine.
-    CodeLocationLabel lastProtoBegin = prototypeStructures->list[currentIndex - 1].stubRoutine;
+    CodeLocationLabel lastProtoBegin = CodeLocationLabel(JITStubRoutine::asCodePtr(prototypeStructures->list[currentIndex - 1].stubRoutine));
     patchBuffer.link(failureCases1, lastProtoBegin);
-    patchBuffer.link(failureCases2, lastProtoBegin);
+    if (failureCases2.isSet())
+        patchBuffer.link(failureCases2, lastProtoBegin);
     
     // On success return back to the hot patch code, at a point it will perform the store to dest for us.
-    patchBuffer.link(success, stubInfo->hotPathBegin.labelAtOffset(patchOffsetGetByIdPutResult));
+    patchBuffer.link(success, stubInfo->hotPathBegin.labelAtOffset(stubInfo->patch.baseline.u.get.putResult));
     
-    CodeLocationLabel entryLabel = patchBuffer.finalizeCodeAddendum();
-    
-    structure->ref();
-    prototypeStructure->ref();
-    prototypeStructures->list[currentIndex].set(entryLabel, structure, prototypeStructure);
+    RefPtr<JITStubRoutine> stubRoutine = createJITStubRoutine(
+        FINALIZE_CODE(
+            patchBuffer,
+            ("Baseline get_by_id proto list stub for %s, return point %p",
+                toCString(*m_codeBlock).data(), stubInfo->hotPathBegin.labelAtOffset(
+                    stubInfo->patch.baseline.u.get.putResult).executableAddress())),
+        *m_vm,
+        m_codeBlock->ownerExecutable(),
+        needsStubLink);
+
+    prototypeStructures->list[currentIndex].set(callFrame->vm(), m_codeBlock->ownerExecutable(), stubRoutine, structure, prototypeStructure, isDirect);
     
     // Finally patch the jump to slow case back in the hot path to jump here instead.
-    CodeLocationJump jumpLocation = stubInfo->hotPathBegin.jumpAtOffset(patchOffsetGetByIdBranchToSlowCase);
+    CodeLocationJump jumpLocation = stubInfo->hotPathBegin.jumpAtOffset(stubInfo->patch.baseline.u.get.structureCheck);
     RepatchBuffer repatchBuffer(m_codeBlock);
-    repatchBuffer.relink(jumpLocation, entryLabel);
+    repatchBuffer.relink(jumpLocation, CodeLocationLabel(stubRoutine->code().code()));
 }
 
-void JIT::privateCompileGetByIdChainList(StructureStubInfo* stubInfo, PolymorphicAccessStructureList* prototypeStructures, int currentIndex, Structure* structure, StructureChain* chain, size_t count, const Identifier& ident, const PropertySlot& slot, size_t cachedOffset, CallFrame* callFrame)
+void JIT::privateCompileGetByIdChainList(StructureStubInfo* stubInfo, PolymorphicAccessStructureList* prototypeStructures, int currentIndex, Structure* structure, StructureChain* chain, size_t count, const Identifier& ident, const PropertySlot& slot, PropertyOffset cachedOffset, CallFrame* callFrame)
 {
     // regT0 holds a JSCell*
     ASSERT(count);
@@ -974,46 +1026,41 @@ void JIT::privateCompileGetByIdChainList(StructureStubInfo* stubInfo, Polymorphi
     bucketsOfFail.append(checkStructure(regT0, structure));
     
     Structure* currStructure = structure;
-    RefPtr<Structure>* chainEntries = chain->head();
+    WriteBarrier<Structure>* it = chain->head();
     JSObject* protoObject = 0;
-    for (unsigned i = 0; i < count; ++i) {
+    for (unsigned i = 0; i < count; ++i, ++it) {
         protoObject = asObject(currStructure->prototypeForLookup(callFrame));
-        currStructure = chainEntries[i].get();
-        
-        // Check the prototype object's Structure had not changed.
-        Structure** prototypeStructureAddress = &(protoObject->m_structure);
-#if CPU(X86_64)
-        move(ImmPtr(currStructure), regT3);
-        bucketsOfFail.append(branchPtr(NotEqual, AbsoluteAddress(prototypeStructureAddress), regT3));
-#else
-        bucketsOfFail.append(branchPtr(NotEqual, AbsoluteAddress(prototypeStructureAddress), ImmPtr(currStructure)));
-#endif
+        currStructure = it->get();
+        testPrototype(protoObject, bucketsOfFail, stubInfo);
     }
     ASSERT(protoObject);
     
     bool needsStubLink = false;
+    bool isDirect = false;
     if (slot.cachedPropertyType() == PropertySlot::Getter) {
         needsStubLink = true;
-        compileGetDirectOffset(protoObject, regT2, regT2, regT1, cachedOffset);
+        compileGetDirectOffset(protoObject, regT2, regT1, cachedOffset);
         JITStubCall stubCall(this, cti_op_get_by_id_getter_stub);
         stubCall.addArgument(regT1);
         stubCall.addArgument(regT0);
-        stubCall.addArgument(ImmPtr(stubInfo->callReturnLocation.executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(stubInfo->callReturnLocation.executableAddress()));
         stubCall.call();
     } else if (slot.cachedPropertyType() == PropertySlot::Custom) {
         needsStubLink = true;
         JITStubCall stubCall(this, cti_op_get_by_id_custom_stub);
-        stubCall.addArgument(ImmPtr(protoObject));
-        stubCall.addArgument(ImmPtr(FunctionPtr(slot.customGetter()).executableAddress()));
-        stubCall.addArgument(ImmPtr(const_cast<Identifier*>(&ident)));
-        stubCall.addArgument(ImmPtr(stubInfo->callReturnLocation.executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(protoObject));
+        stubCall.addArgument(TrustedImmPtr(FunctionPtr(slot.customGetter()).executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(const_cast<Identifier*>(&ident)));
+        stubCall.addArgument(TrustedImmPtr(stubInfo->callReturnLocation.executableAddress()));
         stubCall.call();
-    } else
-        compileGetDirectOffset(protoObject, regT2, regT1, regT0, cachedOffset);
+    } else {
+        isDirect = true;
+        compileGetDirectOffset(protoObject, regT1, regT0, cachedOffset);
+    }
 
     Jump success = jump();
     
-    LinkBuffer patchBuffer(this, m_codeBlock->executablePool(), 0);
+    LinkBuffer patchBuffer(*m_vm, this, m_codeBlock);
     if (needsStubLink) {
         for (Vector<CallRecord>::iterator iter = m_calls.begin(); iter != m_calls.end(); ++iter) {
             if (iter->to)
@@ -1021,27 +1068,33 @@ void JIT::privateCompileGetByIdChainList(StructureStubInfo* stubInfo, Polymorphi
         }
     }
     // Use the patch information to link the failure cases back to the original slow case routine.
-    CodeLocationLabel lastProtoBegin = prototypeStructures->list[currentIndex - 1].stubRoutine;
+    CodeLocationLabel lastProtoBegin = CodeLocationLabel(JITStubRoutine::asCodePtr(prototypeStructures->list[currentIndex - 1].stubRoutine));
     
     patchBuffer.link(bucketsOfFail, lastProtoBegin);
     
     // On success return back to the hot patch code, at a point it will perform the store to dest for us.
-    patchBuffer.link(success, stubInfo->hotPathBegin.labelAtOffset(patchOffsetGetByIdPutResult));
-    
-    CodeLocationLabel entryLabel = patchBuffer.finalizeCodeAddendum();
+    patchBuffer.link(success, stubInfo->hotPathBegin.labelAtOffset(stubInfo->patch.baseline.u.get.putResult));
+    
+    RefPtr<JITStubRoutine> stubRoutine = createJITStubRoutine(
+        FINALIZE_CODE(
+            patchBuffer,
+            ("Baseline get_by_id chain list stub for %s, return point %p",
+                toCString(*m_codeBlock).data(), stubInfo->hotPathBegin.labelAtOffset(
+                    stubInfo->patch.baseline.u.get.putResult).executableAddress())),
+        *m_vm,
+        m_codeBlock->ownerExecutable(),
+        needsStubLink);
     
     // Track the stub we have created so that it will be deleted later.
-    structure->ref();
-    chain->ref();
-    prototypeStructures->list[currentIndex].set(entryLabel, structure, chain);
+    prototypeStructures->list[currentIndex].set(callFrame->vm(), m_codeBlock->ownerExecutable(), stubRoutine, structure, chain, isDirect);
     
     // Finally patch the jump to slow case back in the hot path to jump here instead.
-    CodeLocationJump jumpLocation = stubInfo->hotPathBegin.jumpAtOffset(patchOffsetGetByIdBranchToSlowCase);
+    CodeLocationJump jumpLocation = stubInfo->hotPathBegin.jumpAtOffset(stubInfo->patch.baseline.u.get.structureCheck);
     RepatchBuffer repatchBuffer(m_codeBlock);
-    repatchBuffer.relink(jumpLocation, entryLabel);
+    repatchBuffer.relink(jumpLocation, CodeLocationLabel(stubRoutine->code().code()));
 }
 
-void JIT::privateCompileGetByIdChain(StructureStubInfo* stubInfo, Structure* structure, StructureChain* chain, size_t count, const Identifier& ident, const PropertySlot& slot, size_t cachedOffset, ReturnAddressPtr returnAddress, CallFrame* callFrame)
+void JIT::privateCompileGetByIdChain(StructureStubInfo* stubInfo, Structure* structure, StructureChain* chain, size_t count, const Identifier& ident, const PropertySlot& slot, PropertyOffset cachedOffset, ReturnAddressPtr returnAddress, CallFrame* callFrame)
 {
     // regT0 holds a JSCell*
     ASSERT(count);
@@ -1052,45 +1105,37 @@ void JIT::privateCompileGetByIdChain(StructureStubInfo* stubInfo, Structure* str
     bucketsOfFail.append(checkStructure(regT0, structure));
     
     Structure* currStructure = structure;
-    RefPtr<Structure>* chainEntries = chain->head();
+    WriteBarrier<Structure>* it = chain->head();
     JSObject* protoObject = 0;
-    for (unsigned i = 0; i < count; ++i) {
+    for (unsigned i = 0; i < count; ++i, ++it) {
         protoObject = asObject(currStructure->prototypeForLookup(callFrame));
-        currStructure = chainEntries[i].get();
-        
-        // Check the prototype object's Structure had not changed.
-        Structure** prototypeStructureAddress = &(protoObject->m_structure);
-#if CPU(X86_64)
-        move(ImmPtr(currStructure), regT3);
-        bucketsOfFail.append(branchPtr(NotEqual, AbsoluteAddress(prototypeStructureAddress), regT3));
-#else
-        bucketsOfFail.append(branchPtr(NotEqual, AbsoluteAddress(prototypeStructureAddress), ImmPtr(currStructure)));
-#endif
+        currStructure = it->get();
+        testPrototype(protoObject, bucketsOfFail, stubInfo);
     }
     ASSERT(protoObject);
     
     bool needsStubLink = false;
     if (slot.cachedPropertyType() == PropertySlot::Getter) {
         needsStubLink = true;
-        compileGetDirectOffset(protoObject, regT2, regT2, regT1, cachedOffset);
+        compileGetDirectOffset(protoObject, regT2, regT1, cachedOffset);
         JITStubCall stubCall(this, cti_op_get_by_id_getter_stub);
         stubCall.addArgument(regT1);
         stubCall.addArgument(regT0);
-        stubCall.addArgument(ImmPtr(stubInfo->callReturnLocation.executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(stubInfo->callReturnLocation.executableAddress()));
         stubCall.call();
     } else if (slot.cachedPropertyType() == PropertySlot::Custom) {
         needsStubLink = true;
         JITStubCall stubCall(this, cti_op_get_by_id_custom_stub);
-        stubCall.addArgument(ImmPtr(protoObject));
-        stubCall.addArgument(ImmPtr(FunctionPtr(slot.customGetter()).executableAddress()));
-        stubCall.addArgument(ImmPtr(const_cast<Identifier*>(&ident)));
-        stubCall.addArgument(ImmPtr(stubInfo->callReturnLocation.executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(protoObject));
+        stubCall.addArgument(TrustedImmPtr(FunctionPtr(slot.customGetter()).executableAddress()));
+        stubCall.addArgument(TrustedImmPtr(const_cast<Identifier*>(&ident)));
+        stubCall.addArgument(TrustedImmPtr(stubInfo->callReturnLocation.executableAddress()));
         stubCall.call();
     } else
-        compileGetDirectOffset(protoObject, regT2, regT1, regT0, cachedOffset);
+        compileGetDirectOffset(protoObject, regT1, regT0, cachedOffset);
     Jump success = jump();
     
-    LinkBuffer patchBuffer(this, m_codeBlock->executablePool(), 0);
+    LinkBuffer patchBuffer(*m_vm, this, m_codeBlock);
     if (needsStubLink) {
         for (Vector<CallRecord>::iterator iter = m_calls.begin(); iter != m_calls.end(); ++iter) {
             if (iter->to)
@@ -1098,43 +1143,55 @@ void JIT::privateCompileGetByIdChain(StructureStubInfo* stubInfo, Structure* str
         }
     }
     // Use the patch information to link the failure cases back to the original slow case routine.
-    patchBuffer.link(bucketsOfFail, stubInfo->callReturnLocation.labelAtOffset(-patchOffsetGetByIdSlowCaseCall));
+    patchBuffer.link(bucketsOfFail, stubInfo->callReturnLocation.labelAtOffset(-stubInfo->patch.baseline.u.get.coldPathBegin));
     
     // On success return back to the hot patch code, at a point it will perform the store to dest for us.
-    patchBuffer.link(success, stubInfo->hotPathBegin.labelAtOffset(patchOffsetGetByIdPutResult));
+    patchBuffer.link(success, stubInfo->hotPathBegin.labelAtOffset(stubInfo->patch.baseline.u.get.putResult));
     
     // Track the stub we have created so that it will be deleted later.
-    CodeLocationLabel entryLabel = patchBuffer.finalizeCodeAddendum();
-    stubInfo->stubRoutine = entryLabel;
+    RefPtr<JITStubRoutine> stubRoutine = createJITStubRoutine(
+        FINALIZE_CODE(
+            patchBuffer,
+            ("Baseline get_by_id chain stub for %s, return point %p",
+                toCString(*m_codeBlock).data(), stubInfo->hotPathBegin.labelAtOffset(
+                    stubInfo->patch.baseline.u.get.putResult).executableAddress())),
+        *m_vm,
+        m_codeBlock->ownerExecutable(),
+        needsStubLink);
+    stubInfo->stubRoutine = stubRoutine;
     
     // Finally patch the jump to slow case back in the hot path to jump here instead.
-    CodeLocationJump jumpLocation = stubInfo->hotPathBegin.jumpAtOffset(patchOffsetGetByIdBranchToSlowCase);
+    CodeLocationJump jumpLocation = stubInfo->hotPathBegin.jumpAtOffset(stubInfo->patch.baseline.u.get.structureCheck);
     RepatchBuffer repatchBuffer(m_codeBlock);
-    repatchBuffer.relink(jumpLocation, entryLabel);
+    repatchBuffer.relink(jumpLocation, CodeLocationLabel(stubRoutine->code().code()));
     
     // We don't want to patch more than once - in future go to cti_op_put_by_id_generic.
     repatchBuffer.relinkCallerToFunction(returnAddress, FunctionPtr(cti_op_get_by_id_proto_list));
 }
 
-/* ------------------------------ END: !ENABLE / ENABLE(JIT_OPTIMIZE_PROPERTY_ACCESS) ------------------------------ */
-
-#endif // !ENABLE(JIT_OPTIMIZE_PROPERTY_ACCESS)
-
-void JIT::compileGetDirectOffset(RegisterID base, RegisterID resultTag, RegisterID resultPayload, RegisterID structure, RegisterID offset)
+void JIT::compileGetDirectOffset(RegisterID base, RegisterID resultTag, RegisterID resultPayload, RegisterID offset, FinalObjectMode finalObjectMode)
 {
-    ASSERT(sizeof(((Structure*)0)->m_propertyStorageCapacity) == sizeof(int32_t));
-    ASSERT(sizeof(JSObject::inlineStorageCapacity) == sizeof(int32_t));
     ASSERT(sizeof(JSValue) == 8);
     
-    Jump notUsingInlineStorage = branch32(NotEqual, Address(structure, OBJECT_OFFSETOF(Structure, m_propertyStorageCapacity)), Imm32(JSObject::inlineStorageCapacity));
-    loadPtr(BaseIndex(base, offset, TimesEight, OBJECT_OFFSETOF(JSObject, m_inlineStorage)+OBJECT_OFFSETOF(JSValue, u.asBits.payload)), resultPayload);
-    loadPtr(BaseIndex(base, offset, TimesEight, OBJECT_OFFSETOF(JSObject, m_inlineStorage)+OBJECT_OFFSETOF(JSValue, u.asBits.tag)), resultTag);
-    Jump finishedLoad = jump();
-    notUsingInlineStorage.link(this);
-    loadPtr(Address(base, OBJECT_OFFSETOF(JSObject, m_externalStorage)), base);
-    loadPtr(BaseIndex(base, offset, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.payload)), resultPayload);
-    loadPtr(BaseIndex(base, offset, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.tag)), resultTag);
-    finishedLoad.link(this);
+    if (finalObjectMode == MayBeFinal) {
+        Jump isInline = branch32(LessThan, offset, TrustedImm32(firstOutOfLineOffset));
+        loadPtr(Address(base, JSObject::butterflyOffset()), base);
+        neg32(offset);
+        Jump done = jump();
+        isInline.link(this);
+        addPtr(TrustedImmPtr(JSObject::offsetOfInlineStorage() - (firstOutOfLineOffset - 2) * sizeof(EncodedJSValue)), base);
+        done.link(this);
+    } else {
+#if !ASSERT_DISABLED
+        Jump isOutOfLine = branch32(GreaterThanOrEqual, offset, TrustedImm32(firstOutOfLineOffset));
+        breakpoint();
+        isOutOfLine.link(this);
+#endif
+        loadPtr(Address(base, JSObject::butterflyOffset()), base);
+        neg32(offset);
+    }
+    load32(BaseIndex(base, offset, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.payload) + (firstOutOfLineOffset - 2) * sizeof(EncodedJSValue)), resultPayload);
+    load32(BaseIndex(base, offset, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.tag) + (firstOutOfLineOffset - 2) * sizeof(EncodedJSValue)), resultTag);
 }
 
 void JIT::emit_op_get_by_pname(Instruction* currentInstruction)
@@ -1154,15 +1211,19 @@ void JIT::emit_op_get_by_pname(Instruction* currentInstruction)
     emitLoadPayload(iter, regT1);
     
     // Test base's structure
-    loadPtr(Address(regT2, OBJECT_OFFSETOF(JSCell, m_structure)), regT0);
+    loadPtr(Address(regT2, JSCell::structureOffset()), regT0);
     addSlowCase(branchPtr(NotEqual, regT0, Address(regT1, OBJECT_OFFSETOF(JSPropertyNameIterator, m_cachedStructure))));
     load32(addressFor(i), regT3);
-    sub32(Imm32(1), regT3);
+    sub32(TrustedImm32(1), regT3);
     addSlowCase(branch32(AboveOrEqual, regT3, Address(regT1, OBJECT_OFFSETOF(JSPropertyNameIterator, m_numCacheableSlots))));
-    compileGetDirectOffset(regT2, regT1, regT0, regT0, regT3);    
+    Jump inlineProperty = branch32(Below, regT3, Address(regT1, OBJECT_OFFSETOF(JSPropertyNameIterator, m_cachedStructureInlineCapacity)));
+    add32(TrustedImm32(firstOutOfLineOffset), regT3);
+    sub32(Address(regT1, OBJECT_OFFSETOF(JSPropertyNameIterator, m_cachedStructureInlineCapacity)), regT3);
+    inlineProperty.link(this);
+    compileGetDirectOffset(regT2, regT1, regT0, regT3);    
     
     emitStore(dst, regT1, regT0);
-    map(m_bytecodeIndex + OPCODE_LENGTH(op_get_by_pname), dst, regT1, regT0);
+    map(m_bytecodeOffset + OPCODE_LENGTH(op_get_by_pname), dst, regT1, regT0);
 }
 
 void JIT::emitSlow_op_get_by_pname(Instruction* currentInstruction, Vector<SlowCaseEntry>::iterator& iter)
@@ -1177,15 +1238,137 @@ void JIT::emitSlow_op_get_by_pname(Instruction* currentInstruction, Vector<SlowC
     linkSlowCase(iter);
     linkSlowCase(iter);
     
-    JITStubCall stubCall(this, cti_op_get_by_val);
+    JITStubCall stubCall(this, cti_op_get_by_val_generic);
     stubCall.addArgument(base);
     stubCall.addArgument(property);
     stubCall.call(dst);
 }
 
-} // namespace JSC
+void JIT::emit_op_get_scoped_var(Instruction* currentInstruction)
+{
+    int dst = currentInstruction[1].u.operand;
+    int index = currentInstruction[2].u.operand;
+    int skip = currentInstruction[3].u.operand;
+
+    emitGetFromCallFrameHeaderPtr(JSStack::ScopeChain, regT2);
+    bool checkTopLevel = m_codeBlock->codeType() == FunctionCode && m_codeBlock->needsFullScopeChain();
+    ASSERT(skip || !checkTopLevel);
+    if (checkTopLevel && skip--) {
+        Jump activationNotCreated;
+        if (checkTopLevel)
+            activationNotCreated = branch32(Equal, tagFor(m_codeBlock->activationRegister()), TrustedImm32(JSValue::EmptyValueTag));
+        loadPtr(Address(regT2, JSScope::offsetOfNext()), regT2);
+        activationNotCreated.link(this);
+    }
+    while (skip--)
+        loadPtr(Address(regT2, JSScope::offsetOfNext()), regT2);
 
-#endif // ENABLE(JIT)
+    loadPtr(Address(regT2, JSVariableObject::offsetOfRegisters()), regT2);
+
+    emitLoad(index, regT1, regT0, regT2);
+    emitValueProfilingSite();
+    emitStore(dst, regT1, regT0);
+    map(m_bytecodeOffset + OPCODE_LENGTH(op_get_scoped_var), dst, regT1, regT0);
+}
+
+void JIT::emit_op_put_scoped_var(Instruction* currentInstruction)
+{
+    int index = currentInstruction[1].u.operand;
+    int skip = currentInstruction[2].u.operand;
+    int value = currentInstruction[3].u.operand;
 
-#endif // ENABLE(JSVALUE32_64)
+    emitLoad(value, regT1, regT0);
+
+    emitGetFromCallFrameHeaderPtr(JSStack::ScopeChain, regT2);
+    bool checkTopLevel = m_codeBlock->codeType() == FunctionCode && m_codeBlock->needsFullScopeChain();
+    ASSERT(skip || !checkTopLevel);
+    if (checkTopLevel && skip--) {
+        Jump activationNotCreated;
+        if (checkTopLevel)
+            activationNotCreated = branch32(Equal, tagFor(m_codeBlock->activationRegister()), TrustedImm32(JSValue::EmptyValueTag));
+        loadPtr(Address(regT2, JSScope::offsetOfNext()), regT2);
+        activationNotCreated.link(this);
+    }
+    while (skip--)
+        loadPtr(Address(regT2, JSScope::offsetOfNext()), regT2);
 
+    loadPtr(Address(regT2, JSVariableObject::offsetOfRegisters()), regT3);
+    emitStore(index, regT1, regT0, regT3);
+    emitWriteBarrier(regT2, regT1, regT0, regT1, ShouldFilterImmediates, WriteBarrierForVariableAccess);
+}
+
+void JIT::emit_op_init_global_const(Instruction* currentInstruction)
+{
+    WriteBarrier<Unknown>* registerPointer = currentInstruction[1].u.registerPointer;
+    int value = currentInstruction[2].u.operand;
+
+    JSGlobalObject* globalObject = m_codeBlock->globalObject();
+
+    emitLoad(value, regT1, regT0);
+    
+    if (Heap::isWriteBarrierEnabled()) {
+        move(TrustedImmPtr(globalObject), regT2);
+        
+        emitWriteBarrier(globalObject, regT1, regT3, ShouldFilterImmediates, WriteBarrierForVariableAccess);
+    }
+
+    store32(regT1, registerPointer->tagPointer());
+    store32(regT0, registerPointer->payloadPointer());
+    map(m_bytecodeOffset + OPCODE_LENGTH(op_init_global_const), value, regT1, regT0);
+}
+
+void JIT::emit_op_init_global_const_check(Instruction* currentInstruction)
+{
+    WriteBarrier<Unknown>* registerPointer = currentInstruction[1].u.registerPointer;
+    int value = currentInstruction[2].u.operand;
+    
+    JSGlobalObject* globalObject = m_codeBlock->globalObject();
+    
+    emitLoad(value, regT1, regT0);
+    
+    addSlowCase(branchTest8(NonZero, AbsoluteAddress(currentInstruction[3].u.predicatePointer)));
+    
+    if (Heap::isWriteBarrierEnabled()) {
+        move(TrustedImmPtr(globalObject), regT2);
+        emitWriteBarrier(globalObject, regT1, regT3, ShouldFilterImmediates, WriteBarrierForVariableAccess);
+    }
+    
+    store32(regT1, registerPointer->tagPointer());
+    store32(regT0, registerPointer->payloadPointer());
+    unmap();
+}
+
+void JIT::emitSlow_op_init_global_const_check(Instruction* currentInstruction, Vector<SlowCaseEntry>::iterator& iter)
+{
+    linkSlowCase(iter);
+    
+    JITStubCall stubCall(this, cti_op_init_global_const_check);
+    stubCall.addArgument(regT1, regT0);
+    stubCall.addArgument(TrustedImm32(currentInstruction[4].u.operand));
+    stubCall.call();
+}
+
+void JIT::resetPatchGetById(RepatchBuffer& repatchBuffer, StructureStubInfo* stubInfo)
+{
+    repatchBuffer.relink(stubInfo->callReturnLocation, cti_op_get_by_id);
+    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabelPtrAtOffset(stubInfo->patch.baseline.u.get.structureToCompare), reinterpret_cast<void*>(unusedPointer));
+    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabelCompactAtOffset(stubInfo->patch.baseline.u.get.displacementLabel1), 0);
+    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabelCompactAtOffset(stubInfo->patch.baseline.u.get.displacementLabel2), 0);
+    repatchBuffer.relink(stubInfo->hotPathBegin.jumpAtOffset(stubInfo->patch.baseline.u.get.structureCheck), stubInfo->callReturnLocation.labelAtOffset(-stubInfo->patch.baseline.u.get.coldPathBegin));
+}
+
+void JIT::resetPatchPutById(RepatchBuffer& repatchBuffer, StructureStubInfo* stubInfo)
+{
+    if (isDirectPutById(stubInfo))
+        repatchBuffer.relink(stubInfo->callReturnLocation, cti_op_put_by_id_direct);
+    else
+        repatchBuffer.relink(stubInfo->callReturnLocation, cti_op_put_by_id);
+    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabelPtrAtOffset(stubInfo->patch.baseline.u.put.structureToCompare), reinterpret_cast<void*>(unusedPointer));
+    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabel32AtOffset(stubInfo->patch.baseline.u.put.displacementLabel1), 0);
+    repatchBuffer.repatch(stubInfo->hotPathBegin.dataLabel32AtOffset(stubInfo->patch.baseline.u.put.displacementLabel2), 0);
+}
+
+} // namespace JSC
+
+#endif // USE(JSVALUE32_64)
+#endif // ENABLE(JIT)