webkitgtk-2.16.5HEADwebkitgtk-2.16.5master

1 files changed, 1729 insertions, 765 deletions

diff --git a/Source/JavaScriptCore/jit/JITOperations.cpp b/Source/JavaScriptCore/jit/JITOperations.cpp
index 578d15dac..a1d4e7351 100644
--- a/Source/JavaScriptCore/jit/JITOperations.cpp
+++ b/Source/JavaScriptCore/jit/JITOperations.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013 Apple Inc. All rights reserved.
+ * Copyright (C) 2013-2017 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -24,32 +24,53 @@
  */
 
 #include "config.h"
-#if ENABLE(JIT)
 #include "JITOperations.h"
 
-#include "Arguments.h"
+#if ENABLE(JIT)
+
+#include "ArithProfile.h"
 #include "ArrayConstructor.h"
-#include "CallFrameInlines.h"
 #include "CommonSlowPaths.h"
 #include "DFGCompilationMode.h"
 #include "DFGDriver.h"
 #include "DFGOSREntry.h"
+#include "DFGThunks.h"
 #include "DFGWorklist.h"
+#include "Debugger.h"
+#include "DirectArguments.h"
 #include "Error.h"
+#include "ErrorHandlingScope.h"
+#include "EvalCodeBlock.h"
+#include "ExceptionFuzz.h"
+#include "FunctionCodeBlock.h"
 #include "GetterSetter.h"
 #include "HostCallReturnValue.h"
+#include "ICStats.h"
+#include "Interpreter.h"
 #include "JIT.h"
-#include "JITOperationWrappers.h"
+#include "JITExceptions.h"
 #include "JITToDFGDeferredCompilationCallback.h"
+#include "JSAsyncFunction.h"
+#include "JSCInlines.h"
+#include "JSGeneratorFunction.h"
 #include "JSGlobalObjectFunctions.h"
-#include "JSNameScope.h"
-#include "JSPropertyNameIterator.h"
-#include "JSStackInlines.h"
-#include "JSWithScope.h"
+#include "JSLexicalEnvironment.h"
+#include "JSPropertyNameEnumerator.h"
+#include "ModuleProgramCodeBlock.h"
 #include "ObjectConstructor.h"
-#include "Operations.h"
+#include "PolymorphicAccess.h"
+#include "ProgramCodeBlock.h"
+#include "PropertyName.h"
+#include "RegExpObject.h"
 #include "Repatch.h"
-#include "RepatchBuffer.h"
+#include "ScopedArguments.h"
+#include "ShadowChicken.h"
+#include "StructureStubInfo.h"
+#include "SuperSampler.h"
+#include "TestRunnerUtils.h"
+#include "TypeProfilerLog.h"
+#include "VMInlines.h"
+#include <wtf/InlineASM.h>
 
 namespace JSC {
 
@@ -71,33 +92,63 @@ void * _ReturnAddress(void);
 #endif
 
 
-void JIT_OPERATION operationStackCheck(ExecState* exec, CodeBlock* codeBlock)
+void JIT_OPERATION operationThrowStackOverflowError(ExecState* exec, CodeBlock* codeBlock)
 {
     // We pass in our own code block, because the callframe hasn't been populated.
     VM* vm = codeBlock->vm();
-    CallFrame* callerFrame = exec->callerFrameSkippingVMEntrySentinel();
-    if (!callerFrame)
+    auto scope = DECLARE_THROW_SCOPE(*vm);
+
+    VMEntryFrame* vmEntryFrame = vm->topVMEntryFrame;
+    CallFrame* callerFrame = exec->callerFrame(vmEntryFrame);
+    if (!callerFrame) {
         callerFrame = exec;
+        vmEntryFrame = vm->topVMEntryFrame;
+    }
+
+    NativeCallFrameTracerWithRestore tracer(vm, vmEntryFrame, callerFrame);
+    throwStackOverflowError(callerFrame, scope);
+}
 
-    NativeCallFrameTracer tracer(vm, callerFrame);
+#if ENABLE(WEBASSEMBLY)
+void JIT_OPERATION operationThrowDivideError(ExecState* exec)
+{
+    VM* vm = &exec->vm();
+    auto scope = DECLARE_THROW_SCOPE(*vm);
 
-    JSStack& stack = vm->interpreter->stack();
+    VMEntryFrame* vmEntryFrame = vm->topVMEntryFrame;
+    CallFrame* callerFrame = exec->callerFrame(vmEntryFrame);
 
-    if (UNLIKELY(!stack.grow(&exec->registers()[virtualRegisterForLocal(codeBlock->frameRegisterCount()).offset()])))
-        vm->throwException(callerFrame, createStackOverflowError(callerFrame));
+    NativeCallFrameTracerWithRestore tracer(vm, vmEntryFrame, callerFrame);
+    ErrorHandlingScope errorScope(*vm);
+    throwException(callerFrame, scope, createError(callerFrame, ASCIILiteral("Division by zero or division overflow.")));
 }
 
-int32_t JIT_OPERATION operationCallArityCheck(ExecState* exec)
+void JIT_OPERATION operationThrowOutOfBoundsAccessError(ExecState* exec)
 {
     VM* vm = &exec->vm();
-    CallFrame* callerFrame = exec->callerFrameSkippingVMEntrySentinel();
-    NativeCallFrameTracer tracer(vm, callerFrame);
+    auto scope = DECLARE_THROW_SCOPE(*vm);
 
-    JSStack& stack = vm->interpreter->stack();
+    VMEntryFrame* vmEntryFrame = vm->topVMEntryFrame;
+    CallFrame* callerFrame = exec->callerFrame(vmEntryFrame);
 
-    int32_t missingArgCount = CommonSlowPaths::arityCheckFor(exec, &stack, CodeForCall);
-    if (missingArgCount < 0)
-        vm->throwException(callerFrame, createStackOverflowError(callerFrame));
+    NativeCallFrameTracerWithRestore tracer(vm, vmEntryFrame, callerFrame);
+    ErrorHandlingScope errorScope(*vm);
+    throwException(callerFrame, scope, createError(callerFrame, ASCIILiteral("Out-of-bounds access.")));
+}
+#endif
+
+int32_t JIT_OPERATION operationCallArityCheck(ExecState* exec)
+{
+    VM* vm = &exec->vm();
+    auto scope = DECLARE_THROW_SCOPE(*vm);
+
+    int32_t missingArgCount = CommonSlowPaths::arityCheckFor(exec, *vm, CodeForCall);
+    if (missingArgCount < 0) {
+        VMEntryFrame* vmEntryFrame = vm->topVMEntryFrame;
+        CallFrame* callerFrame = exec->callerFrame(vmEntryFrame);
+        NativeCallFrameTracerWithRestore tracer(vm, vmEntryFrame, callerFrame);
+        throwStackOverflowError(callerFrame, scope);
+    }
 
     return missingArgCount;
 }
@@ -105,489 +156,616 @@ int32_t JIT_OPERATION operationCallArityCheck(ExecState* exec)
 int32_t JIT_OPERATION operationConstructArityCheck(ExecState* exec)
 {
     VM* vm = &exec->vm();
-    CallFrame* callerFrame = exec->callerFrameSkippingVMEntrySentinel();
-    NativeCallFrameTracer tracer(vm, callerFrame);
-
-    JSStack& stack = vm->interpreter->stack();
-
-    int32_t missingArgCount = CommonSlowPaths::arityCheckFor(exec, &stack, CodeForConstruct);
-    if (missingArgCount < 0)
-        vm->throwException(callerFrame, createStackOverflowError(callerFrame));
+    auto scope = DECLARE_THROW_SCOPE(*vm);
+
+    int32_t missingArgCount = CommonSlowPaths::arityCheckFor(exec, *vm, CodeForConstruct);
+    if (missingArgCount < 0) {
+        VMEntryFrame* vmEntryFrame = vm->topVMEntryFrame;
+        CallFrame* callerFrame = exec->callerFrame(vmEntryFrame);
+        NativeCallFrameTracerWithRestore tracer(vm, vmEntryFrame, callerFrame);
+        throwStackOverflowError(callerFrame, scope);
+    }
 
     return missingArgCount;
 }
 
-EncodedJSValue JIT_OPERATION operationGetById(ExecState* exec, StructureStubInfo*, EncodedJSValue base, StringImpl* uid)
+EncodedJSValue JIT_OPERATION operationTryGetById(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue base, UniquedStringImpl* uid)
 {
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
-    
+    Identifier ident = Identifier::fromUid(vm, uid);
+    stubInfo->tookSlowPath = true;
+
     JSValue baseValue = JSValue::decode(base);
-    PropertySlot slot(baseValue);
-    Identifier ident(vm, uid);
-    return JSValue::encode(baseValue.get(exec, ident, slot));
+    PropertySlot slot(baseValue, PropertySlot::InternalMethodType::VMInquiry);
+    baseValue.getPropertySlot(exec, ident, slot);
+
+    return JSValue::encode(slot.getPureResult());
 }
 
-EncodedJSValue JIT_OPERATION operationGetByIdBuildList(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue base, StringImpl* uid)
+
+EncodedJSValue JIT_OPERATION operationTryGetByIdGeneric(ExecState* exec, EncodedJSValue base, UniquedStringImpl* uid)
 {
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
+    Identifier ident = Identifier::fromUid(vm, uid);
 
-    Identifier ident(vm, uid);
-    AccessType accessType = static_cast<AccessType>(stubInfo->accessType);
+    JSValue baseValue = JSValue::decode(base);
+    PropertySlot slot(baseValue, PropertySlot::InternalMethodType::VMInquiry);
+    baseValue.getPropertySlot(exec, ident, slot);
+
+    return JSValue::encode(slot.getPureResult());
+}
+
+EncodedJSValue JIT_OPERATION operationTryGetByIdOptimize(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue base, UniquedStringImpl* uid)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+    auto scope = DECLARE_THROW_SCOPE(*vm);
+    Identifier ident = Identifier::fromUid(vm, uid);
 
     JSValue baseValue = JSValue::decode(base);
-    PropertySlot slot(baseValue);
-    JSValue result = baseValue.get(exec, ident, slot);
+    PropertySlot slot(baseValue, PropertySlot::InternalMethodType::VMInquiry);
 
-    if (accessType == static_cast<AccessType>(stubInfo->accessType))
-        buildGetByIDList(exec, baseValue, ident, slot, *stubInfo);
+    baseValue.getPropertySlot(exec, ident, slot);
+    RETURN_IF_EXCEPTION(scope, encodedJSValue());
 
-    return JSValue::encode(result);
+    if (stubInfo->considerCaching(exec->codeBlock(), baseValue.structureOrNull()) && !slot.isTaintedByOpaqueObject() && (slot.isCacheableValue() || slot.isCacheableGetter() || slot.isUnset()))
+        repatchGetByID(exec, baseValue, ident, slot, *stubInfo, GetByIDKind::Try);
+
+    return JSValue::encode(slot.getPureResult());
 }
 
-EncodedJSValue JIT_OPERATION operationGetByIdOptimize(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue base, StringImpl* uid)
+EncodedJSValue JIT_OPERATION operationGetById(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue base, UniquedStringImpl* uid)
 {
+    SuperSamplerScope superSamplerScope(false);
+    
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
-    Identifier ident = uid->isEmptyUnique() ? Identifier::from(PrivateName(uid)) : Identifier(vm, uid);
-    AccessType accessType = static_cast<AccessType>(stubInfo->accessType);
-
+    
+    stubInfo->tookSlowPath = true;
+    
     JSValue baseValue = JSValue::decode(base);
-    PropertySlot slot(baseValue);
-    JSValue result = baseValue.get(exec, ident, slot);
+    PropertySlot slot(baseValue, PropertySlot::InternalMethodType::Get);
+    Identifier ident = Identifier::fromUid(vm, uid);
     
-    if (accessType == static_cast<AccessType>(stubInfo->accessType)) {
-        if (stubInfo->seen)
-            repatchGetByID(exec, baseValue, ident, slot, *stubInfo);
-        else
-            stubInfo->seen = true;
-    }
+    LOG_IC((ICEvent::OperationGetById, baseValue.classInfoOrNull(*vm), ident));
+    return JSValue::encode(baseValue.get(exec, ident, slot));
+}
 
-    return JSValue::encode(result);
+EncodedJSValue JIT_OPERATION operationGetByIdGeneric(ExecState* exec, EncodedJSValue base, UniquedStringImpl* uid)
+{
+    SuperSamplerScope superSamplerScope(false);
+    
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+    
+    JSValue baseValue = JSValue::decode(base);
+    PropertySlot slot(baseValue, PropertySlot::InternalMethodType::Get);
+    Identifier ident = Identifier::fromUid(vm, uid);
+    LOG_IC((ICEvent::OperationGetByIdGeneric, baseValue.classInfoOrNull(*vm), ident));
+    return JSValue::encode(baseValue.get(exec, ident, slot));
 }
 
-EncodedJSValue JIT_OPERATION operationInOptimize(ExecState* exec, StructureStubInfo* stubInfo, JSCell* base, StringImpl* key)
+EncodedJSValue JIT_OPERATION operationGetByIdOptimize(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue base, UniquedStringImpl* uid)
 {
+    SuperSamplerScope superSamplerScope(false);
+    
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
+    Identifier ident = Identifier::fromUid(vm, uid);
+
+    JSValue baseValue = JSValue::decode(base);
+    LOG_IC((ICEvent::OperationGetByIdOptimize, baseValue.classInfoOrNull(*vm), ident));
+
+    return JSValue::encode(baseValue.getPropertySlot(exec, ident, [&] (bool found, PropertySlot& slot) -> JSValue {
+        if (stubInfo->considerCaching(exec->codeBlock(), baseValue.structureOrNull()))
+            repatchGetByID(exec, baseValue, ident, slot, *stubInfo, GetByIDKind::Normal);
+        return found ? slot.getValue(exec, ident) : jsUndefined();
+    }));
+}
+
+EncodedJSValue JIT_OPERATION operationInOptimize(ExecState* exec, StructureStubInfo* stubInfo, JSCell* base, UniquedStringImpl* key)
+{
+    SuperSamplerScope superSamplerScope(false);
     
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+    auto scope = DECLARE_THROW_SCOPE(*vm);
+
     if (!base->isObject()) {
-        vm->throwException(exec, createInvalidParameterError(exec, "in", base));
+        throwException(exec, scope, createInvalidInParameterError(exec, base));
         return JSValue::encode(jsUndefined());
     }
     
     AccessType accessType = static_cast<AccessType>(stubInfo->accessType);
 
-    Identifier ident(vm, key);
-    PropertySlot slot(base);
+    Identifier ident = Identifier::fromUid(vm, key);
+    LOG_IC((ICEvent::OperationInOptimize, base->classInfo(*vm), ident));
+    PropertySlot slot(base, PropertySlot::InternalMethodType::HasProperty);
     bool result = asObject(base)->getPropertySlot(exec, ident, slot);
+    RETURN_IF_EXCEPTION(scope, encodedJSValue());
     
     RELEASE_ASSERT(accessType == stubInfo->accessType);
     
-    if (stubInfo->seen)
+    if (stubInfo->considerCaching(exec->codeBlock(), asObject(base)->structure()))
         repatchIn(exec, base, ident, result, slot, *stubInfo);
-    else
-        stubInfo->seen = true;
     
     return JSValue::encode(jsBoolean(result));
 }
 
-EncodedJSValue JIT_OPERATION operationIn(ExecState* exec, StructureStubInfo*, JSCell* base, StringImpl* key)
+EncodedJSValue JIT_OPERATION operationIn(ExecState* exec, StructureStubInfo* stubInfo, JSCell* base, UniquedStringImpl* key)
 {
+    SuperSamplerScope superSamplerScope(false);
+    
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
+    auto scope = DECLARE_THROW_SCOPE(*vm);
+
+    stubInfo->tookSlowPath = true;
 
     if (!base->isObject()) {
-        vm->throwException(exec, createInvalidParameterError(exec, "in", base));
+        throwException(exec, scope, createInvalidInParameterError(exec, base));
         return JSValue::encode(jsUndefined());
     }
 
-    Identifier ident(vm, key);
+    Identifier ident = Identifier::fromUid(vm, key);
+    LOG_IC((ICEvent::OperationIn, base->classInfo(*vm), ident));
     return JSValue::encode(jsBoolean(asObject(base)->hasProperty(exec, ident)));
 }
 
 EncodedJSValue JIT_OPERATION operationGenericIn(ExecState* exec, JSCell* base, EncodedJSValue key)
 {
+    SuperSamplerScope superSamplerScope(false);
+    
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
 
-    return JSValue::encode(jsBoolean(CommonSlowPaths::opIn(exec, JSValue::decode(key), base)));
+    return JSValue::encode(jsBoolean(CommonSlowPaths::opIn(exec, base, JSValue::decode(key))));
 }
 
-EncodedJSValue JIT_OPERATION operationCallCustomGetter(ExecState* exec, JSCell* base, PropertySlot::GetValueFunc function, StringImpl* uid)
+void JIT_OPERATION operationPutByIdStrict(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, UniquedStringImpl* uid)
 {
+    SuperSamplerScope superSamplerScope(false);
+    
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
     
-    Identifier ident(vm, uid);
+    stubInfo->tookSlowPath = true;
     
-    return function(exec, JSValue::encode(base), JSValue::encode(base), ident);
-}
-
-EncodedJSValue JIT_OPERATION operationCallGetter(ExecState* exec, JSCell* base, JSCell* getterSetter)
-{
-    VM* vm = &exec->vm();
-    NativeCallFrameTracer tracer(vm, exec);
+    JSValue baseValue = JSValue::decode(encodedBase);
+    Identifier ident = Identifier::fromUid(vm, uid);
+    LOG_IC((ICEvent::OperationPutByIdStrict, baseValue.classInfoOrNull(*vm), ident));
 
-    return JSValue::encode(callGetter(exec, base, getterSetter));
+    PutPropertySlot slot(baseValue, true, exec->codeBlock()->putByIdContext());
+    baseValue.putInline(exec, ident, JSValue::decode(encodedValue), slot);
 }
 
-void JIT_OPERATION operationPutByIdStrict(ExecState* exec, StructureStubInfo*, EncodedJSValue encodedValue, EncodedJSValue encodedBase, StringImpl* uid)
+void JIT_OPERATION operationPutByIdNonStrict(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, UniquedStringImpl* uid)
 {
-    VM* vm = &exec->vm();
-    NativeCallFrameTracer tracer(vm, exec);
+    SuperSamplerScope superSamplerScope(false);
     
-    Identifier ident(vm, uid);
-    PutPropertySlot slot(JSValue::decode(encodedBase), true, exec->codeBlock()->putByIdContext());
-    JSValue::decode(encodedBase).put(exec, ident, JSValue::decode(encodedValue), slot);
-}
-
-void JIT_OPERATION operationPutByIdNonStrict(ExecState* exec, StructureStubInfo*, EncodedJSValue encodedValue, EncodedJSValue encodedBase, StringImpl* uid)
-{
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
     
-    Identifier ident(vm, uid);
-    PutPropertySlot slot(JSValue::decode(encodedBase), false, exec->codeBlock()->putByIdContext());
-    JSValue::decode(encodedBase).put(exec, ident, JSValue::decode(encodedValue), slot);
-}
-
-void JIT_OPERATION operationPutByIdDirectStrict(ExecState* exec, StructureStubInfo*, EncodedJSValue encodedValue, EncodedJSValue encodedBase, StringImpl* uid)
-{
-    VM* vm = &exec->vm();
-    NativeCallFrameTracer tracer(vm, exec);
+    stubInfo->tookSlowPath = true;
     
-    Identifier ident(vm, uid);
-    PutPropertySlot slot(JSValue::decode(encodedBase), true, exec->codeBlock()->putByIdContext());
-    asObject(JSValue::decode(encodedBase))->putDirect(exec->vm(), ident, JSValue::decode(encodedValue), slot);
+    JSValue baseValue = JSValue::decode(encodedBase);
+    Identifier ident = Identifier::fromUid(vm, uid);
+    LOG_IC((ICEvent::OperationPutByIdNonStrict, baseValue.classInfoOrNull(*vm), ident));
+    PutPropertySlot slot(baseValue, false, exec->codeBlock()->putByIdContext());
+    baseValue.putInline(exec, ident, JSValue::decode(encodedValue), slot);
 }
 
-void JIT_OPERATION operationPutByIdDirectNonStrict(ExecState* exec, StructureStubInfo*, EncodedJSValue encodedValue, EncodedJSValue encodedBase, StringImpl* uid)
+void JIT_OPERATION operationPutByIdDirectStrict(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, UniquedStringImpl* uid)
 {
-    VM* vm = &exec->vm();
-    NativeCallFrameTracer tracer(vm, exec);
+    SuperSamplerScope superSamplerScope(false);
     
-    Identifier ident(vm, uid);
-    PutPropertySlot slot(JSValue::decode(encodedBase), false, exec->codeBlock()->putByIdContext());
-    asObject(JSValue::decode(encodedBase))->putDirect(exec->vm(), ident, JSValue::decode(encodedValue), slot);
-}
-
-void JIT_OPERATION operationPutByIdStrictOptimize(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, StringImpl* uid)
-{
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
     
-    Identifier ident(vm, uid);
-    AccessType accessType = static_cast<AccessType>(stubInfo->accessType);
-
-    JSValue value = JSValue::decode(encodedValue);
+    stubInfo->tookSlowPath = true;
+    
     JSValue baseValue = JSValue::decode(encodedBase);
+    Identifier ident = Identifier::fromUid(vm, uid);
+    LOG_IC((ICEvent::OperationPutByIdDirectStrict, baseValue.classInfoOrNull(*vm), ident));
     PutPropertySlot slot(baseValue, true, exec->codeBlock()->putByIdContext());
-    
-    baseValue.put(exec, ident, value, slot);
-    
-    if (accessType != static_cast<AccessType>(stubInfo->accessType))
-        return;
-    
-    if (stubInfo->seen)
-        repatchPutByID(exec, baseValue, ident, slot, *stubInfo, NotDirect);
-    else
-        stubInfo->seen = true;
+    asObject(baseValue)->putDirect(exec->vm(), ident, JSValue::decode(encodedValue), slot);
 }
 
-void JIT_OPERATION operationPutByIdNonStrictOptimize(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, StringImpl* uid)
+void JIT_OPERATION operationPutByIdDirectNonStrict(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, UniquedStringImpl* uid)
 {
+    SuperSamplerScope superSamplerScope(false);
+    
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
     
-    Identifier ident(vm, uid);
-    AccessType accessType = static_cast<AccessType>(stubInfo->accessType);
-
-    JSValue value = JSValue::decode(encodedValue);
+    stubInfo->tookSlowPath = true;
+    
     JSValue baseValue = JSValue::decode(encodedBase);
+    Identifier ident = Identifier::fromUid(vm, uid);
+    LOG_IC((ICEvent::OperationPutByIdDirectNonStrict, baseValue.classInfoOrNull(*vm), ident));
     PutPropertySlot slot(baseValue, false, exec->codeBlock()->putByIdContext());
-    
-    baseValue.put(exec, ident, value, slot);
-    
-    if (accessType != static_cast<AccessType>(stubInfo->accessType))
-        return;
-    
-    if (stubInfo->seen)
-        repatchPutByID(exec, baseValue, ident, slot, *stubInfo, NotDirect);
-    else
-        stubInfo->seen = true;
+    asObject(baseValue)->putDirect(exec->vm(), ident, JSValue::decode(encodedValue), slot);
 }
 
-void JIT_OPERATION operationPutByIdDirectStrictOptimize(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, StringImpl* uid)
+void JIT_OPERATION operationPutByIdStrictOptimize(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, UniquedStringImpl* uid)
 {
+    SuperSamplerScope superSamplerScope(false);
+    
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
-    
-    Identifier ident(vm, uid);
+    auto scope = DECLARE_THROW_SCOPE(*vm);
+
+    Identifier ident = Identifier::fromUid(vm, uid);
     AccessType accessType = static_cast<AccessType>(stubInfo->accessType);
 
     JSValue value = JSValue::decode(encodedValue);
-    JSObject* baseObject = asObject(JSValue::decode(encodedBase));
-    PutPropertySlot slot(baseObject, true, exec->codeBlock()->putByIdContext());
-    
-    baseObject->putDirect(exec->vm(), ident, value, slot);
-    
-    if (accessType != static_cast<AccessType>(stubInfo->accessType))
-        return;
-    
-    if (stubInfo->seen)
-        repatchPutByID(exec, baseObject, ident, slot, *stubInfo, Direct);
-    else
-        stubInfo->seen = true;
-}
+    JSValue baseValue = JSValue::decode(encodedBase);
+    LOG_IC((ICEvent::OperationPutByIdStrictOptimize, baseValue.classInfoOrNull(*vm), ident));
+    CodeBlock* codeBlock = exec->codeBlock();
+    PutPropertySlot slot(baseValue, true, codeBlock->putByIdContext());
 
-void JIT_OPERATION operationPutByIdDirectNonStrictOptimize(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, StringImpl* uid)
-{
-    VM* vm = &exec->vm();
-    NativeCallFrameTracer tracer(vm, exec);
-    
-    Identifier ident(vm, uid);
-    AccessType accessType = static_cast<AccessType>(stubInfo->accessType);
+    Structure* structure = baseValue.isCell() ? baseValue.asCell()->structure(*vm) : nullptr;
+    baseValue.putInline(exec, ident, value, slot);
+    RETURN_IF_EXCEPTION(scope, void());
 
-    JSValue value = JSValue::decode(encodedValue);
-    JSObject* baseObject = asObject(JSValue::decode(encodedBase));
-    PutPropertySlot slot(baseObject, false, exec->codeBlock()->putByIdContext());
-    
-    baseObject->putDirect(exec->vm(), ident, value, slot);
-    
     if (accessType != static_cast<AccessType>(stubInfo->accessType))
         return;
     
-    if (stubInfo->seen)
-        repatchPutByID(exec, baseObject, ident, slot, *stubInfo, Direct);
-    else
-        stubInfo->seen = true;
+    if (stubInfo->considerCaching(codeBlock, structure))
+        repatchPutByID(exec, baseValue, structure, ident, slot, *stubInfo, NotDirect);
 }
 
-void JIT_OPERATION operationPutByIdStrictBuildList(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, StringImpl* uid)
+void JIT_OPERATION operationPutByIdNonStrictOptimize(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, UniquedStringImpl* uid)
 {
+    SuperSamplerScope superSamplerScope(false);
+    
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
-    
-    Identifier ident(vm, uid);
+    auto scope = DECLARE_THROW_SCOPE(*vm);
+
+    Identifier ident = Identifier::fromUid(vm, uid);
     AccessType accessType = static_cast<AccessType>(stubInfo->accessType);
 
     JSValue value = JSValue::decode(encodedValue);
     JSValue baseValue = JSValue::decode(encodedBase);
-    PutPropertySlot slot(baseValue, true, exec->codeBlock()->putByIdContext());
-    
-    baseValue.put(exec, ident, value, slot);
-    
-    if (accessType != static_cast<AccessType>(stubInfo->accessType))
-        return;
-    
-    buildPutByIdList(exec, baseValue, ident, slot, *stubInfo, NotDirect);
-}
+    LOG_IC((ICEvent::OperationPutByIdNonStrictOptimize, baseValue.classInfoOrNull(*vm), ident));
+    CodeBlock* codeBlock = exec->codeBlock();
+    PutPropertySlot slot(baseValue, false, codeBlock->putByIdContext());
 
-void JIT_OPERATION operationPutByIdNonStrictBuildList(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, StringImpl* uid)
-{
-    VM* vm = &exec->vm();
-    NativeCallFrameTracer tracer(vm, exec);
-    
-    Identifier ident(vm, uid);
-    AccessType accessType = static_cast<AccessType>(stubInfo->accessType);
+    Structure* structure = baseValue.isCell() ? baseValue.asCell()->structure(*vm) : nullptr;    
+    baseValue.putInline(exec, ident, value, slot);
+    RETURN_IF_EXCEPTION(scope, void());
 
-    JSValue value = JSValue::decode(encodedValue);
-    JSValue baseValue = JSValue::decode(encodedBase);
-    PutPropertySlot slot(baseValue, false, exec->codeBlock()->putByIdContext());
-    
-    baseValue.put(exec, ident, value, slot);
-    
     if (accessType != static_cast<AccessType>(stubInfo->accessType))
         return;
     
-    buildPutByIdList(exec, baseValue, ident, slot, *stubInfo, NotDirect);
+    if (stubInfo->considerCaching(codeBlock, structure))
+        repatchPutByID(exec, baseValue, structure, ident, slot, *stubInfo, NotDirect);
 }
 
-void JIT_OPERATION operationPutByIdDirectStrictBuildList(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, StringImpl* uid)
+void JIT_OPERATION operationPutByIdDirectStrictOptimize(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, UniquedStringImpl* uid)
 {
+    SuperSamplerScope superSamplerScope(false);
+    
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
     
-    Identifier ident(vm, uid);
+    Identifier ident = Identifier::fromUid(vm, uid);
     AccessType accessType = static_cast<AccessType>(stubInfo->accessType);
-    
+
     JSValue value = JSValue::decode(encodedValue);
     JSObject* baseObject = asObject(JSValue::decode(encodedBase));
-    PutPropertySlot slot(baseObject, true, exec->codeBlock()->putByIdContext());
+    LOG_IC((ICEvent::OperationPutByIdDirectStrictOptimize, baseObject->classInfo(*vm), ident));
+    CodeBlock* codeBlock = exec->codeBlock();
+    PutPropertySlot slot(baseObject, true, codeBlock->putByIdContext());
     
+    Structure* structure = baseObject->structure(*vm);
     baseObject->putDirect(exec->vm(), ident, value, slot);
     
     if (accessType != static_cast<AccessType>(stubInfo->accessType))
         return;
     
-    buildPutByIdList(exec, baseObject, ident, slot, *stubInfo, Direct);
+    if (stubInfo->considerCaching(codeBlock, structure))
+        repatchPutByID(exec, baseObject, structure, ident, slot, *stubInfo, Direct);
 }
 
-void JIT_OPERATION operationPutByIdDirectNonStrictBuildList(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, StringImpl* uid)
+void JIT_OPERATION operationPutByIdDirectNonStrictOptimize(ExecState* exec, StructureStubInfo* stubInfo, EncodedJSValue encodedValue, EncodedJSValue encodedBase, UniquedStringImpl* uid)
 {
+    SuperSamplerScope superSamplerScope(false);
+    
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
     
-    Identifier ident(vm, uid);
+    Identifier ident = Identifier::fromUid(vm, uid);
     AccessType accessType = static_cast<AccessType>(stubInfo->accessType);
 
     JSValue value = JSValue::decode(encodedValue);
     JSObject* baseObject = asObject(JSValue::decode(encodedBase));
-    PutPropertySlot slot(baseObject, false, exec->codeBlock()->putByIdContext());
+    LOG_IC((ICEvent::OperationPutByIdDirectNonStrictOptimize, baseObject->classInfo(*vm), ident));
+    CodeBlock* codeBlock = exec->codeBlock();
+    PutPropertySlot slot(baseObject, false, codeBlock->putByIdContext());
     
-    baseObject ->putDirect(exec->vm(), ident, value, slot);
+    Structure* structure = baseObject->structure(*vm);
+    baseObject->putDirect(exec->vm(), ident, value, slot);
     
     if (accessType != static_cast<AccessType>(stubInfo->accessType))
         return;
     
-    buildPutByIdList(exec, baseObject, ident, slot, *stubInfo, Direct);
+    if (stubInfo->considerCaching(codeBlock, structure))
+        repatchPutByID(exec, baseObject, structure, ident, slot, *stubInfo, Direct);
 }
 
-void JIT_OPERATION operationReallocateStorageAndFinishPut(ExecState* exec, JSObject* base, Structure* structure, PropertyOffset offset, EncodedJSValue value)
+ALWAYS_INLINE static bool isStringOrSymbol(JSValue value)
 {
-    VM& vm = exec->vm();
-    NativeCallFrameTracer tracer(&vm, exec);
-
-    ASSERT(structure->outOfLineCapacity() > base->structure()->outOfLineCapacity());
-    ASSERT(!vm.heap.storageAllocator().fastPathShouldSucceed(structure->outOfLineCapacity() * sizeof(JSValue)));
-    base->setStructureAndReallocateStorageIfNecessary(vm, structure);
-    base->putDirect(vm, offset, JSValue::decode(value));
+    return value.isString() || value.isSymbol();
 }
 
-static void putByVal(CallFrame* callFrame, JSValue baseValue, JSValue subscript, JSValue value)
+static void putByVal(CallFrame* callFrame, JSValue baseValue, JSValue subscript, JSValue value, ByValInfo* byValInfo)
 {
+    VM& vm = callFrame->vm();
+    auto scope = DECLARE_THROW_SCOPE(vm);
     if (LIKELY(subscript.isUInt32())) {
+        byValInfo->tookSlowPath = true;
         uint32_t i = subscript.asUInt32();
         if (baseValue.isObject()) {
             JSObject* object = asObject(baseValue);
             if (object->canSetIndexQuickly(i))
                 object->setIndexQuickly(callFrame->vm(), i, value);
-            else
-                object->methodTable()->putByIndex(object, callFrame, i, value, callFrame->codeBlock()->isStrictMode());
+            else {
+                // FIXME: This will make us think that in-bounds typed array accesses are actually
+                // out-of-bounds.
+                // https://bugs.webkit.org/show_bug.cgi?id=149886
+                byValInfo->arrayProfile->setOutOfBounds();
+                object->methodTable(vm)->putByIndex(object, callFrame, i, value, callFrame->codeBlock()->isStrictMode());
+            }
         } else
             baseValue.putByIndex(callFrame, i, value, callFrame->codeBlock()->isStrictMode());
-    } else if (isName(subscript)) {
-        PutPropertySlot slot(baseValue, callFrame->codeBlock()->isStrictMode());
-        baseValue.put(callFrame, jsCast<NameInstance*>(subscript.asCell())->privateName(), value, slot);
-    } else {
-        Identifier property(callFrame, subscript.toString(callFrame)->value(callFrame));
-        if (!callFrame->vm().exception()) { // Don't put to an object if toString threw an exception.
-            PutPropertySlot slot(baseValue, callFrame->codeBlock()->isStrictMode());
-            baseValue.put(callFrame, property, value, slot);
-        }
+        return;
     }
+
+    auto property = subscript.toPropertyKey(callFrame);
+    // Don't put to an object if toString threw an exception.
+    RETURN_IF_EXCEPTION(scope, void());
+
+    if (byValInfo->stubInfo && (!isStringOrSymbol(subscript) || byValInfo->cachedId != property))
+        byValInfo->tookSlowPath = true;
+
+    scope.release();
+    PutPropertySlot slot(baseValue, callFrame->codeBlock()->isStrictMode());
+    baseValue.putInline(callFrame, property, value, slot);
 }
 
-static void directPutByVal(CallFrame* callFrame, JSObject* baseObject, JSValue subscript, JSValue value)
+static void directPutByVal(CallFrame* callFrame, JSObject* baseObject, JSValue subscript, JSValue value, ByValInfo* byValInfo)
 {
+    VM& vm = callFrame->vm();
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    bool isStrictMode = callFrame->codeBlock()->isStrictMode();
     if (LIKELY(subscript.isUInt32())) {
-        uint32_t i = subscript.asUInt32();
-        baseObject->putDirectIndex(callFrame, i, value);
-    } else if (isName(subscript)) {
-        PutPropertySlot slot(baseObject, callFrame->codeBlock()->isStrictMode());
-        baseObject->putDirect(callFrame->vm(), jsCast<NameInstance*>(subscript.asCell())->privateName(), value, slot);
-    } else {
-        Identifier property(callFrame, subscript.toString(callFrame)->value(callFrame));
-        if (!callFrame->vm().exception()) { // Don't put to an object if toString threw an exception.
-            PutPropertySlot slot(baseObject, callFrame->codeBlock()->isStrictMode());
-            baseObject->putDirect(callFrame->vm(), property, value, slot);
+        // Despite its name, JSValue::isUInt32 will return true only for positive boxed int32_t; all those values are valid array indices.
+        byValInfo->tookSlowPath = true;
+        uint32_t index = subscript.asUInt32();
+        ASSERT(isIndex(index));
+        if (baseObject->canSetIndexQuicklyForPutDirect(index)) {
+            baseObject->setIndexQuickly(callFrame->vm(), index, value);
+            return;
         }
+
+        // FIXME: This will make us think that in-bounds typed array accesses are actually
+        // out-of-bounds.
+        // https://bugs.webkit.org/show_bug.cgi?id=149886
+        byValInfo->arrayProfile->setOutOfBounds();
+        baseObject->putDirectIndex(callFrame, index, value, 0, isStrictMode ? PutDirectIndexShouldThrow : PutDirectIndexShouldNotThrow);
+        return;
+    }
+
+    if (subscript.isDouble()) {
+        double subscriptAsDouble = subscript.asDouble();
+        uint32_t subscriptAsUInt32 = static_cast<uint32_t>(subscriptAsDouble);
+        if (subscriptAsDouble == subscriptAsUInt32 && isIndex(subscriptAsUInt32)) {
+            byValInfo->tookSlowPath = true;
+            baseObject->putDirectIndex(callFrame, subscriptAsUInt32, value, 0, isStrictMode ? PutDirectIndexShouldThrow : PutDirectIndexShouldNotThrow);
+            return;
+        }
+    }
+
+    // Don't put to an object if toString threw an exception.
+    auto property = subscript.toPropertyKey(callFrame);
+    RETURN_IF_EXCEPTION(scope, void());
+
+    if (std::optional<uint32_t> index = parseIndex(property)) {
+        byValInfo->tookSlowPath = true;
+        baseObject->putDirectIndex(callFrame, index.value(), value, 0, isStrictMode ? PutDirectIndexShouldThrow : PutDirectIndexShouldNotThrow);
+        return;
     }
+
+    if (byValInfo->stubInfo && (!isStringOrSymbol(subscript) || byValInfo->cachedId != property))
+        byValInfo->tookSlowPath = true;
+
+    PutPropertySlot slot(baseObject, isStrictMode);
+    baseObject->putDirect(callFrame->vm(), property, value, slot);
 }
-void JIT_OPERATION operationPutByVal(ExecState* exec, EncodedJSValue encodedBaseValue, EncodedJSValue encodedSubscript, EncodedJSValue encodedValue)
+
+enum class OptimizationResult {
+    NotOptimized,
+    SeenOnce,
+    Optimized,
+    GiveUp,
+};
+
+static OptimizationResult tryPutByValOptimize(ExecState* exec, JSValue baseValue, JSValue subscript, ByValInfo* byValInfo, ReturnAddressPtr returnAddress)
 {
-    VM& vm = exec->vm();
-    NativeCallFrameTracer tracer(&vm, exec);
+    // See if it's worth optimizing at all.
+    OptimizationResult optimizationResult = OptimizationResult::NotOptimized;
 
-    JSValue baseValue = JSValue::decode(encodedBaseValue);
-    JSValue subscript = JSValue::decode(encodedSubscript);
-    JSValue value = JSValue::decode(encodedValue);
+    VM& vm = exec->vm();
 
     if (baseValue.isObject() && subscript.isInt32()) {
-        // See if it's worth optimizing at all.
         JSObject* object = asObject(baseValue);
-        bool didOptimize = false;
 
-        unsigned bytecodeOffset = exec->locationAsBytecodeOffset();
-        ASSERT(bytecodeOffset);
-        ByValInfo& byValInfo = exec->codeBlock()->getByValInfo(bytecodeOffset - 1);
-        ASSERT(!byValInfo.stubRoutine);
+        ASSERT(exec->bytecodeOffset());
+        ASSERT(!byValInfo->stubRoutine);
 
-        if (hasOptimizableIndexing(object->structure())) {
+        Structure* structure = object->structure(vm);
+        if (hasOptimizableIndexing(structure)) {
             // Attempt to optimize.
-            JITArrayMode arrayMode = jitArrayModeForStructure(object->structure());
-            if (arrayMode != byValInfo.arrayMode) {
-                JIT::compilePutByVal(&vm, exec->codeBlock(), &byValInfo, ReturnAddressPtr(OUR_RETURN_ADDRESS), arrayMode);
-                didOptimize = true;
+            JITArrayMode arrayMode = jitArrayModeForStructure(structure);
+            if (jitArrayModePermitsPut(arrayMode) && arrayMode != byValInfo->arrayMode) {
+                CodeBlock* codeBlock = exec->codeBlock();
+                ConcurrentJSLocker locker(codeBlock->m_lock);
+                byValInfo->arrayProfile->computeUpdatedPrediction(locker, codeBlock, structure);
+
+                JIT::compilePutByVal(&vm, codeBlock, byValInfo, returnAddress, arrayMode);
+                optimizationResult = OptimizationResult::Optimized;
             }
         }
 
-        if (!didOptimize) {
-            // If we take slow path more than 10 times without patching then make sure we
-            // never make that mistake again. Or, if we failed to patch and we have some object
-            // that intercepts indexed get, then don't even wait until 10 times. For cases
-            // where we see non-index-intercepting objects, this gives 10 iterations worth of
-            // opportunity for us to observe that the get_by_val may be polymorphic.
-            if (++byValInfo.slowPathCount >= 10
-                || object->structure()->typeInfo().interceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero()) {
-                // Don't ever try to optimize.
-                RepatchBuffer repatchBuffer(exec->codeBlock());
-                repatchBuffer.relinkCallerToFunction(ReturnAddressPtr(OUR_RETURN_ADDRESS), FunctionPtr(operationPutByValGeneric));
+        // If we failed to patch and we have some object that intercepts indexed get, then don't even wait until 10 times.
+        if (optimizationResult != OptimizationResult::Optimized && object->structure(vm)->typeInfo().interceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero())
+            optimizationResult = OptimizationResult::GiveUp;
+    }
+
+    if (baseValue.isObject() && isStringOrSymbol(subscript)) {
+        const Identifier propertyName = subscript.toPropertyKey(exec);
+        if (subscript.isSymbol() || !parseIndex(propertyName)) {
+            ASSERT(exec->bytecodeOffset());
+            ASSERT(!byValInfo->stubRoutine);
+            if (byValInfo->seen) {
+                if (byValInfo->cachedId == propertyName) {
+                    JIT::compilePutByValWithCachedId(&vm, exec->codeBlock(), byValInfo, returnAddress, NotDirect, propertyName);
+                    optimizationResult = OptimizationResult::Optimized;
+                } else {
+                    // Seem like a generic property access site.
+                    optimizationResult = OptimizationResult::GiveUp;
+                }
+            } else {
+                CodeBlock* codeBlock = exec->codeBlock();
+                ConcurrentJSLocker locker(codeBlock->m_lock);
+                byValInfo->seen = true;
+                byValInfo->cachedId = propertyName;
+                if (subscript.isSymbol())
+                    byValInfo->cachedSymbol.set(vm, codeBlock, asSymbol(subscript));
+                optimizationResult = OptimizationResult::SeenOnce;
             }
         }
     }
 
-    putByVal(exec, baseValue, subscript, value);
+    if (optimizationResult != OptimizationResult::Optimized && optimizationResult != OptimizationResult::SeenOnce) {
+        // If we take slow path more than 10 times without patching then make sure we
+        // never make that mistake again. For cases where we see non-index-intercepting
+        // objects, this gives 10 iterations worth of opportunity for us to observe
+        // that the put_by_val may be polymorphic. We count up slowPathCount even if
+        // the result is GiveUp.
+        if (++byValInfo->slowPathCount >= 10)
+            optimizationResult = OptimizationResult::GiveUp;
+    }
+
+    return optimizationResult;
 }
 
-void JIT_OPERATION operationDirectPutByVal(ExecState* callFrame, EncodedJSValue encodedBaseValue, EncodedJSValue encodedSubscript, EncodedJSValue encodedValue)
+void JIT_OPERATION operationPutByValOptimize(ExecState* exec, EncodedJSValue encodedBaseValue, EncodedJSValue encodedSubscript, EncodedJSValue encodedValue, ByValInfo* byValInfo)
 {
-    VM& vm = callFrame->vm();
-    NativeCallFrameTracer tracer(&vm, callFrame);
-    
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+
     JSValue baseValue = JSValue::decode(encodedBaseValue);
     JSValue subscript = JSValue::decode(encodedSubscript);
     JSValue value = JSValue::decode(encodedValue);
-    RELEASE_ASSERT(baseValue.isObject());
-    JSObject* object = asObject(baseValue);
+    if (tryPutByValOptimize(exec, baseValue, subscript, byValInfo, ReturnAddressPtr(OUR_RETURN_ADDRESS)) == OptimizationResult::GiveUp) {
+        // Don't ever try to optimize.
+        byValInfo->tookSlowPath = true;
+        ctiPatchCallByReturnAddress(ReturnAddressPtr(OUR_RETURN_ADDRESS), FunctionPtr(operationPutByValGeneric));
+    }
+    putByVal(exec, baseValue, subscript, value, byValInfo);
+}
+
+static OptimizationResult tryDirectPutByValOptimize(ExecState* exec, JSObject* object, JSValue subscript, ByValInfo* byValInfo, ReturnAddressPtr returnAddress)
+{
+    // See if it's worth optimizing at all.
+    OptimizationResult optimizationResult = OptimizationResult::NotOptimized;
+
+    VM& vm = exec->vm();
+
     if (subscript.isInt32()) {
-        // See if it's worth optimizing at all.
-        bool didOptimize = false;
-        
-        unsigned bytecodeOffset = callFrame->locationAsBytecodeOffset();
-        ASSERT(bytecodeOffset);
-        ByValInfo& byValInfo = callFrame->codeBlock()->getByValInfo(bytecodeOffset - 1);
-        ASSERT(!byValInfo.stubRoutine);
-        
-        if (hasOptimizableIndexing(object->structure())) {
+        ASSERT(exec->bytecodeOffset());
+        ASSERT(!byValInfo->stubRoutine);
+
+        Structure* structure = object->structure(vm);
+        if (hasOptimizableIndexing(structure)) {
             // Attempt to optimize.
-            JITArrayMode arrayMode = jitArrayModeForStructure(object->structure());
-            if (arrayMode != byValInfo.arrayMode) {
-                JIT::compileDirectPutByVal(&vm, callFrame->codeBlock(), &byValInfo, ReturnAddressPtr(OUR_RETURN_ADDRESS), arrayMode);
-                didOptimize = true;
+            JITArrayMode arrayMode = jitArrayModeForStructure(structure);
+            if (jitArrayModePermitsPut(arrayMode) && arrayMode != byValInfo->arrayMode) {
+                CodeBlock* codeBlock = exec->codeBlock();
+                ConcurrentJSLocker locker(codeBlock->m_lock);
+                byValInfo->arrayProfile->computeUpdatedPrediction(locker, codeBlock, structure);
+
+                JIT::compileDirectPutByVal(&vm, codeBlock, byValInfo, returnAddress, arrayMode);
+                optimizationResult = OptimizationResult::Optimized;
             }
         }
-        
-        if (!didOptimize) {
-            // If we take slow path more than 10 times without patching then make sure we
-            // never make that mistake again. Or, if we failed to patch and we have some object
-            // that intercepts indexed get, then don't even wait until 10 times. For cases
-            // where we see non-index-intercepting objects, this gives 10 iterations worth of
-            // opportunity for us to observe that the get_by_val may be polymorphic.
-            if (++byValInfo.slowPathCount >= 10
-                || object->structure()->typeInfo().interceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero()) {
-                // Don't ever try to optimize.
-                RepatchBuffer repatchBuffer(callFrame->codeBlock());
-                repatchBuffer.relinkCallerToFunction(ReturnAddressPtr(OUR_RETURN_ADDRESS), FunctionPtr(operationDirectPutByValGeneric));
+
+        // If we failed to patch and we have some object that intercepts indexed get, then don't even wait until 10 times.
+        if (optimizationResult != OptimizationResult::Optimized && object->structure(vm)->typeInfo().interceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero())
+            optimizationResult = OptimizationResult::GiveUp;
+    } else if (isStringOrSymbol(subscript)) {
+        const Identifier propertyName = subscript.toPropertyKey(exec);
+        if (subscript.isSymbol() || !parseIndex(propertyName)) {
+            ASSERT(exec->bytecodeOffset());
+            ASSERT(!byValInfo->stubRoutine);
+            if (byValInfo->seen) {
+                if (byValInfo->cachedId == propertyName) {
+                    JIT::compilePutByValWithCachedId(&vm, exec->codeBlock(), byValInfo, returnAddress, Direct, propertyName);
+                    optimizationResult = OptimizationResult::Optimized;
+                } else {
+                    // Seem like a generic property access site.
+                    optimizationResult = OptimizationResult::GiveUp;
+                }
+            } else {
+                CodeBlock* codeBlock = exec->codeBlock();
+                ConcurrentJSLocker locker(codeBlock->m_lock);
+                byValInfo->seen = true;
+                byValInfo->cachedId = propertyName;
+                if (subscript.isSymbol())
+                    byValInfo->cachedSymbol.set(vm, codeBlock, asSymbol(subscript));
+                optimizationResult = OptimizationResult::SeenOnce;
             }
         }
     }
-    directPutByVal(callFrame, object, subscript, value);
+
+    if (optimizationResult != OptimizationResult::Optimized && optimizationResult != OptimizationResult::SeenOnce) {
+        // If we take slow path more than 10 times without patching then make sure we
+        // never make that mistake again. For cases where we see non-index-intercepting
+        // objects, this gives 10 iterations worth of opportunity for us to observe
+        // that the get_by_val may be polymorphic. We count up slowPathCount even if
+        // the result is GiveUp.
+        if (++byValInfo->slowPathCount >= 10)
+            optimizationResult = OptimizationResult::GiveUp;
+    }
+
+    return optimizationResult;
 }
 
-void JIT_OPERATION operationPutByValGeneric(ExecState* exec, EncodedJSValue encodedBaseValue, EncodedJSValue encodedSubscript, EncodedJSValue encodedValue)
+void JIT_OPERATION operationDirectPutByValOptimize(ExecState* exec, EncodedJSValue encodedBaseValue, EncodedJSValue encodedSubscript, EncodedJSValue encodedValue, ByValInfo* byValInfo)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+
+    JSValue baseValue = JSValue::decode(encodedBaseValue);
+    JSValue subscript = JSValue::decode(encodedSubscript);
+    JSValue value = JSValue::decode(encodedValue);
+    RELEASE_ASSERT(baseValue.isObject());
+    JSObject* object = asObject(baseValue);
+    if (tryDirectPutByValOptimize(exec, object, subscript, byValInfo, ReturnAddressPtr(OUR_RETURN_ADDRESS)) == OptimizationResult::GiveUp) {
+        // Don't ever try to optimize.
+        byValInfo->tookSlowPath = true;
+        ctiPatchCallByReturnAddress(ReturnAddressPtr(OUR_RETURN_ADDRESS), FunctionPtr(operationDirectPutByValGeneric));
+    }
+
+    directPutByVal(exec, object, subscript, value, byValInfo);
+}
+
+void JIT_OPERATION operationPutByValGeneric(ExecState* exec, EncodedJSValue encodedBaseValue, EncodedJSValue encodedSubscript, EncodedJSValue encodedValue, ByValInfo* byValInfo)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
@@ -596,11 +774,11 @@ void JIT_OPERATION operationPutByValGeneric(ExecState* exec, EncodedJSValue enco
     JSValue subscript = JSValue::decode(encodedSubscript);
     JSValue value = JSValue::decode(encodedValue);
 
-    putByVal(exec, baseValue, subscript, value);
+    putByVal(exec, baseValue, subscript, value, byValInfo);
 }
 
 
-void JIT_OPERATION operationDirectPutByValGeneric(ExecState* exec, EncodedJSValue encodedBaseValue, EncodedJSValue encodedSubscript, EncodedJSValue encodedValue)
+void JIT_OPERATION operationDirectPutByValGeneric(ExecState* exec, EncodedJSValue encodedBaseValue, EncodedJSValue encodedSubscript, EncodedJSValue encodedValue, ByValInfo* byValInfo)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
@@ -609,218 +787,265 @@ void JIT_OPERATION operationDirectPutByValGeneric(ExecState* exec, EncodedJSValu
     JSValue subscript = JSValue::decode(encodedSubscript);
     JSValue value = JSValue::decode(encodedValue);
     RELEASE_ASSERT(baseValue.isObject());
-    directPutByVal(exec, asObject(baseValue), subscript, value);
+    directPutByVal(exec, asObject(baseValue), subscript, value, byValInfo);
 }
 
-EncodedJSValue JIT_OPERATION operationCallEval(ExecState* execCallee)
+EncodedJSValue JIT_OPERATION operationCallEval(ExecState* exec, ExecState* execCallee)
 {
-    CallFrame* callerFrame = execCallee->callerFrame();
-    ASSERT(execCallee->callerFrame()->codeBlock()->codeType() != FunctionCode
-        || !execCallee->callerFrame()->codeBlock()->needsFullScopeChain()
-        || execCallee->callerFrame()->uncheckedR(execCallee->callerFrame()->codeBlock()->activationRegister().offset()).jsValue());
+    VM* vm = &exec->vm();
+    auto scope = DECLARE_THROW_SCOPE(*vm);
 
-    execCallee->setScope(callerFrame->scope());
-    execCallee->setReturnPC(static_cast<Instruction*>(OUR_RETURN_ADDRESS));
     execCallee->setCodeBlock(0);
-
+    
     if (!isHostFunction(execCallee->calleeAsValue(), globalFuncEval))
         return JSValue::encode(JSValue());
 
-    VM* vm = &execCallee->vm();
     JSValue result = eval(execCallee);
-    if (vm->exception())
-        return EncodedJSValue();
+    RETURN_IF_EXCEPTION(scope, encodedJSValue());
     
     return JSValue::encode(result);
 }
 
-static void* handleHostCall(ExecState* execCallee, JSValue callee, CodeSpecializationKind kind)
+static SlowPathReturnType handleHostCall(ExecState* execCallee, JSValue callee, CallLinkInfo* callLinkInfo)
 {
     ExecState* exec = execCallee->callerFrame();
     VM* vm = &exec->vm();
+    auto scope = DECLARE_THROW_SCOPE(*vm);
 
-    execCallee->setScope(exec->scope());
     execCallee->setCodeBlock(0);
 
-    if (kind == CodeForCall) {
+    if (callLinkInfo->specializationKind() == CodeForCall) {
         CallData callData;
         CallType callType = getCallData(callee, callData);
     
-        ASSERT(callType != CallTypeJS);
+        ASSERT(callType != CallType::JS);
     
-        if (callType == CallTypeHost) {
+        if (callType == CallType::Host) {
             NativeCallFrameTracer tracer(vm, execCallee);
             execCallee->setCallee(asObject(callee));
             vm->hostCallReturnValue = JSValue::decode(callData.native.function(execCallee));
-            if (vm->exception())
-                return vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress();
+            if (UNLIKELY(scope.exception())) {
+                return encodeResult(
+                    vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress(),
+                    reinterpret_cast<void*>(KeepTheFrame));
+            }
 
-            return reinterpret_cast<void*>(getHostCallReturnValue);
+            return encodeResult(
+                bitwise_cast<void*>(getHostCallReturnValue),
+                reinterpret_cast<void*>(callLinkInfo->callMode() == CallMode::Tail ? ReuseTheFrame : KeepTheFrame));
         }
     
-        ASSERT(callType == CallTypeNone);
-        exec->vm().throwException(exec, createNotAFunctionError(exec, callee));
-        return vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress();
+        ASSERT(callType == CallType::None);
+        throwException(exec, scope, createNotAFunctionError(exec, callee));
+        return encodeResult(
+            vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress(),
+            reinterpret_cast<void*>(KeepTheFrame));
     }
 
-    ASSERT(kind == CodeForConstruct);
+    ASSERT(callLinkInfo->specializationKind() == CodeForConstruct);
     
     ConstructData constructData;
     ConstructType constructType = getConstructData(callee, constructData);
     
-    ASSERT(constructType != ConstructTypeJS);
+    ASSERT(constructType != ConstructType::JS);
     
-    if (constructType == ConstructTypeHost) {
+    if (constructType == ConstructType::Host) {
         NativeCallFrameTracer tracer(vm, execCallee);
         execCallee->setCallee(asObject(callee));
         vm->hostCallReturnValue = JSValue::decode(constructData.native.function(execCallee));
-        if (vm->exception())
-            return vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress();
+        if (UNLIKELY(scope.exception())) {
+            return encodeResult(
+                vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress(),
+                reinterpret_cast<void*>(KeepTheFrame));
+        }
 
-        return reinterpret_cast<void*>(getHostCallReturnValue);
+        return encodeResult(bitwise_cast<void*>(getHostCallReturnValue), reinterpret_cast<void*>(KeepTheFrame));
     }
     
-    ASSERT(constructType == ConstructTypeNone);
-    exec->vm().throwException(exec, createNotAConstructorError(exec, callee));
-    return vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress();
+    ASSERT(constructType == ConstructType::None);
+    throwException(exec, scope, createNotAConstructorError(exec, callee));
+    return encodeResult(
+        vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress(),
+        reinterpret_cast<void*>(KeepTheFrame));
 }
 
-inline char* linkFor(ExecState* execCallee, CodeSpecializationKind kind)
+SlowPathReturnType JIT_OPERATION operationLinkCall(ExecState* execCallee, CallLinkInfo* callLinkInfo)
 {
     ExecState* exec = execCallee->callerFrame();
     VM* vm = &exec->vm();
+    auto throwScope = DECLARE_THROW_SCOPE(*vm);
+
+    CodeSpecializationKind kind = callLinkInfo->specializationKind();
     NativeCallFrameTracer tracer(vm, exec);
     
+    RELEASE_ASSERT(!callLinkInfo->isDirect());
+    
     JSValue calleeAsValue = execCallee->calleeAsValue();
     JSCell* calleeAsFunctionCell = getJSFunction(calleeAsValue);
-    if (!calleeAsFunctionCell)
-        return reinterpret_cast<char*>(handleHostCall(execCallee, calleeAsValue, kind));
+    if (!calleeAsFunctionCell) {
+        // FIXME: We should cache these kinds of calls. They can be common and currently they are
+        // expensive.
+        // https://bugs.webkit.org/show_bug.cgi?id=144458
+        throwScope.release();
+        return handleHostCall(execCallee, calleeAsValue, callLinkInfo);
+    }
 
     JSFunction* callee = jsCast<JSFunction*>(calleeAsFunctionCell);
-    execCallee->setScope(callee->scopeUnchecked());
+    JSScope* scope = callee->scopeUnchecked();
     ExecutableBase* executable = callee->executable();
 
     MacroAssemblerCodePtr codePtr;
     CodeBlock* codeBlock = 0;
-    CallLinkInfo& callLinkInfo = exec->codeBlock()->getCallLinkInfo(execCallee->returnPC());
-    if (executable->isHostFunction())
-        codePtr = executable->generatedJITCodeFor(kind)->addressForCall();
-    else {
+    if (executable->isHostFunction()) {
+        codePtr = executable->entrypointFor(kind, MustCheckArity);
+    } else {
         FunctionExecutable* functionExecutable = static_cast<FunctionExecutable*>(executable);
-        JSObject* error = functionExecutable->prepareForExecution(execCallee, callee->scope(), kind);
+
+        if (!isCall(kind) && functionExecutable->constructAbility() == ConstructAbility::CannotConstruct) {
+            throwException(exec, throwScope, createNotAConstructorError(exec, callee));
+            return encodeResult(
+                vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress(),
+                reinterpret_cast<void*>(KeepTheFrame));
+        }
+
+        CodeBlock** codeBlockSlot = execCallee->addressOfCodeBlock();
+        JSObject* error = functionExecutable->prepareForExecution<FunctionExecutable>(*vm, callee, scope, kind, *codeBlockSlot);
+        ASSERT(throwScope.exception() == reinterpret_cast<Exception*>(error));
         if (error) {
-            vm->throwException(exec, createStackOverflowError(exec));
-            return reinterpret_cast<char*>(vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress());
+            throwException(exec, throwScope, error);
+            return encodeResult(
+                vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress(),
+                reinterpret_cast<void*>(KeepTheFrame));
         }
-        codeBlock = functionExecutable->codeBlockFor(kind);
-        if (execCallee->argumentCountIncludingThis() < static_cast<size_t>(codeBlock->numParameters()) || callLinkInfo.callType == CallLinkInfo::CallVarargs)
-            codePtr = functionExecutable->generatedJITCodeWithArityCheckFor(kind);
+        codeBlock = *codeBlockSlot;
+        ArityCheckMode arity;
+        if (execCallee->argumentCountIncludingThis() < static_cast<size_t>(codeBlock->numParameters()) || callLinkInfo->isVarargs())
+            arity = MustCheckArity;
         else
-            codePtr = functionExecutable->generatedJITCodeFor(kind)->addressForCall();
+            arity = ArityCheckNotRequired;
+        codePtr = functionExecutable->entrypointFor(kind, arity);
     }
-    if (!callLinkInfo.seenOnce())
-        callLinkInfo.setSeen();
+    if (!callLinkInfo->seenOnce())
+        callLinkInfo->setSeen();
     else
-        linkFor(execCallee, callLinkInfo, codeBlock, callee, codePtr, kind);
-    return reinterpret_cast<char*>(codePtr.executableAddress());
+        linkFor(execCallee, *callLinkInfo, codeBlock, callee, codePtr);
+    
+    return encodeResult(codePtr.executableAddress(), reinterpret_cast<void*>(callLinkInfo->callMode() == CallMode::Tail ? ReuseTheFrame : KeepTheFrame));
 }
 
-char* JIT_OPERATION operationLinkCall(ExecState* execCallee)
+void JIT_OPERATION operationLinkDirectCall(ExecState* exec, CallLinkInfo* callLinkInfo, JSFunction* callee)
 {
-    return linkFor(execCallee, CodeForCall);
-}
+    VM* vm = &exec->vm();
+    auto throwScope = DECLARE_THROW_SCOPE(*vm);
 
-char* JIT_OPERATION operationLinkConstruct(ExecState* execCallee)
-{
-    return linkFor(execCallee, CodeForConstruct);
+    CodeSpecializationKind kind = callLinkInfo->specializationKind();
+    NativeCallFrameTracer tracer(vm, exec);
+    
+    RELEASE_ASSERT(callLinkInfo->isDirect());
+    
+    // This would happen if the executable died during GC but the CodeBlock did not die. That should
+    // not happen because the CodeBlock should have a weak reference to any executable it uses for
+    // this purpose.
+    RELEASE_ASSERT(callLinkInfo->executable());
+    
+    // Having a CodeBlock indicates that this is linked. We shouldn't be taking this path if it's
+    // linked.
+    RELEASE_ASSERT(!callLinkInfo->codeBlock());
+    
+    // We just don't support this yet.
+    RELEASE_ASSERT(!callLinkInfo->isVarargs());
+    
+    ExecutableBase* executable = callLinkInfo->executable();
+    RELEASE_ASSERT(callee->executable() == callLinkInfo->executable());
+
+    JSScope* scope = callee->scopeUnchecked();
+
+    MacroAssemblerCodePtr codePtr;
+    CodeBlock* codeBlock = nullptr;
+    if (executable->isHostFunction())
+        codePtr = executable->entrypointFor(kind, MustCheckArity);
+    else {
+        FunctionExecutable* functionExecutable = static_cast<FunctionExecutable*>(executable);
+
+        RELEASE_ASSERT(isCall(kind) || functionExecutable->constructAbility() != ConstructAbility::CannotConstruct);
+        
+        JSObject* error = functionExecutable->prepareForExecution<FunctionExecutable>(*vm, callee, scope, kind, codeBlock);
+        ASSERT(throwScope.exception() == reinterpret_cast<Exception*>(error));
+        if (error) {
+            throwException(exec, throwScope, error);
+            return;
+        }
+        ArityCheckMode arity;
+        unsigned argumentStackSlots = callLinkInfo->maxNumArguments();
+        if (argumentStackSlots < static_cast<size_t>(codeBlock->numParameters()))
+            arity = MustCheckArity;
+        else
+            arity = ArityCheckNotRequired;
+        codePtr = functionExecutable->entrypointFor(kind, arity);
+    }
+    
+    linkDirectFor(exec, *callLinkInfo, codeBlock, codePtr);
 }
 
-inline char* virtualForWithFunction(ExecState* execCallee, CodeSpecializationKind kind, JSCell*& calleeAsFunctionCell)
+inline SlowPathReturnType virtualForWithFunction(
+    ExecState* execCallee, CallLinkInfo* callLinkInfo, JSCell*& calleeAsFunctionCell)
 {
     ExecState* exec = execCallee->callerFrame();
     VM* vm = &exec->vm();
+    auto throwScope = DECLARE_THROW_SCOPE(*vm);
+
+    CodeSpecializationKind kind = callLinkInfo->specializationKind();
     NativeCallFrameTracer tracer(vm, exec);
 
     JSValue calleeAsValue = execCallee->calleeAsValue();
     calleeAsFunctionCell = getJSFunction(calleeAsValue);
     if (UNLIKELY(!calleeAsFunctionCell))
-        return reinterpret_cast<char*>(handleHostCall(execCallee, calleeAsValue, kind));
+        return handleHostCall(execCallee, calleeAsValue, callLinkInfo);
     
     JSFunction* function = jsCast<JSFunction*>(calleeAsFunctionCell);
-    execCallee->setScope(function->scopeUnchecked());
+    JSScope* scope = function->scopeUnchecked();
     ExecutableBase* executable = function->executable();
     if (UNLIKELY(!executable->hasJITCodeFor(kind))) {
         FunctionExecutable* functionExecutable = static_cast<FunctionExecutable*>(executable);
-        JSObject* error = functionExecutable->prepareForExecution(execCallee, function->scope(), kind);
-        if (error) {
-            exec->vm().throwException(execCallee, error);
-            return reinterpret_cast<char*>(vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress());
-        }
-    }
-    return reinterpret_cast<char*>(executable->generatedJITCodeWithArityCheckFor(kind).executableAddress());
-}
 
-inline char* virtualFor(ExecState* execCallee, CodeSpecializationKind kind)
-{
-    JSCell* calleeAsFunctionCellIgnored;
-    return virtualForWithFunction(execCallee, kind, calleeAsFunctionCellIgnored);
-}
+        if (!isCall(kind) && functionExecutable->constructAbility() == ConstructAbility::CannotConstruct) {
+            throwException(exec, throwScope, createNotAConstructorError(exec, function));
+            return encodeResult(
+                vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress(),
+                reinterpret_cast<void*>(KeepTheFrame));
+        }
 
-static bool attemptToOptimizeClosureCall(ExecState* execCallee, JSCell* calleeAsFunctionCell, CallLinkInfo& callLinkInfo)
-{
-    if (!calleeAsFunctionCell)
-        return false;
-    
-    JSFunction* callee = jsCast<JSFunction*>(calleeAsFunctionCell);
-    JSFunction* oldCallee = callLinkInfo.callee.get();
-    
-    if (!oldCallee
-        || oldCallee->structure() != callee->structure()
-        || oldCallee->executable() != callee->executable())
-        return false;
-    
-    ASSERT(callee->executable()->hasJITCodeForCall());
-    MacroAssemblerCodePtr codePtr = callee->executable()->generatedJITCodeForCall()->addressForCall();
-    
-    CodeBlock* codeBlock;
-    if (callee->executable()->isHostFunction())
-        codeBlock = 0;
-    else {
-        codeBlock = jsCast<FunctionExecutable*>(callee->executable())->codeBlockForCall();
-        if (execCallee->argumentCountIncludingThis() < static_cast<size_t>(codeBlock->numParameters()))
-            return false;
+        CodeBlock** codeBlockSlot = execCallee->addressOfCodeBlock();
+        JSObject* error = functionExecutable->prepareForExecution<FunctionExecutable>(*vm, function, scope, kind, *codeBlockSlot);
+        if (error) {
+            throwException(exec, throwScope, error);
+            return encodeResult(
+                vm->getCTIStub(throwExceptionFromCallSlowPathGenerator).code().executableAddress(),
+                reinterpret_cast<void*>(KeepTheFrame));
+        }
     }
-    
-    linkClosureCall(
-        execCallee, callLinkInfo, codeBlock,
-        callee->structure(), callee->executable(), codePtr);
-    
-    return true;
+    return encodeResult(executable->entrypointFor(
+        kind, MustCheckArity).executableAddress(),
+        reinterpret_cast<void*>(callLinkInfo->callMode() == CallMode::Tail ? ReuseTheFrame : KeepTheFrame));
 }
 
-char* JIT_OPERATION operationLinkClosureCall(ExecState* execCallee)
+SlowPathReturnType JIT_OPERATION operationLinkPolymorphicCall(ExecState* execCallee, CallLinkInfo* callLinkInfo)
 {
+    ASSERT(callLinkInfo->specializationKind() == CodeForCall);
     JSCell* calleeAsFunctionCell;
-    char* result = virtualForWithFunction(execCallee, CodeForCall, calleeAsFunctionCell);
-    CallLinkInfo& callLinkInfo = execCallee->callerFrame()->codeBlock()->getCallLinkInfo(execCallee->returnPC());
+    SlowPathReturnType result = virtualForWithFunction(execCallee, callLinkInfo, calleeAsFunctionCell);
 
-    if (!attemptToOptimizeClosureCall(execCallee, calleeAsFunctionCell, callLinkInfo))
-        linkSlowFor(execCallee, callLinkInfo, CodeForCall);
+    linkPolymorphicCall(execCallee, *callLinkInfo, CallVariant(calleeAsFunctionCell));
     
     return result;
 }
 
-char* JIT_OPERATION operationVirtualCall(ExecState* execCallee)
-{    
-    return virtualFor(execCallee, CodeForCall);
-}
-
-char* JIT_OPERATION operationVirtualConstruct(ExecState* execCallee)
+SlowPathReturnType JIT_OPERATION operationVirtualCall(ExecState* execCallee, CallLinkInfo* callLinkInfo)
 {
-    return virtualFor(execCallee, CodeForConstruct);
+    JSCell* calleeAsFunctionCellIgnored;
+    return virtualForWithFunction(execCallee, callLinkInfo, calleeAsFunctionCellIgnored);
 }
 
-
 size_t JIT_OPERATION operationCompareLess(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2)
 {
     VM* vm = &exec->vm();
@@ -853,14 +1078,6 @@ size_t JIT_OPERATION operationCompareGreaterEq(ExecState* exec, EncodedJSValue e
     return jsLessEq<false>(exec, JSValue::decode(encodedOp2), JSValue::decode(encodedOp1));
 }
 
-size_t JIT_OPERATION operationConvertJSValueToBoolean(ExecState* exec, EncodedJSValue encodedOp)
-{
-    VM* vm = &exec->vm();
-    NativeCallFrameTracer tracer(vm, exec);
-    
-    return JSValue::decode(encodedOp).toBoolean(exec);
-}
-
 size_t JIT_OPERATION operationCompareEq(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2)
 {
     VM* vm = &exec->vm();
@@ -878,7 +1095,7 @@ size_t JIT_OPERATION operationCompareStringEq(ExecState* exec, JSCell* left, JSC
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
 
-    bool result = asString(left)->value(exec) == asString(right)->value(exec);
+    bool result = asString(left)->equal(exec, asString(right));
 #if USE(JSVALUE64)
     return JSValue::encode(jsBoolean(result));
 #else
@@ -886,13 +1103,6 @@ size_t JIT_OPERATION operationCompareStringEq(ExecState* exec, JSCell* left, JSC
 #endif
 }
 
-size_t JIT_OPERATION operationHasProperty(ExecState* exec, JSObject* base, JSString* property)
-{
-    int result = base->hasProperty(exec, Identifier(exec, property->value(exec)));
-    return result;
-}
-    
-
 EncodedJSValue JIT_OPERATION operationNewArrayWithProfile(ExecState* exec, ArrayAllocationProfile* profile, const JSValue* values, int size)
 {
     VM* vm = &exec->vm();
@@ -915,66 +1125,117 @@ EncodedJSValue JIT_OPERATION operationNewArrayWithSizeAndProfile(ExecState* exec
     return JSValue::encode(constructArrayWithSizeQuirk(exec, profile, exec->lexicalGlobalObject(), sizeValue));
 }
 
-EncodedJSValue JIT_OPERATION operationNewFunction(ExecState* exec, JSCell* functionExecutable)
+}
+
+template<typename FunctionType>
+static EncodedJSValue operationNewFunctionCommon(ExecState* exec, JSScope* scope, JSCell* functionExecutable, bool isInvalidated)
 {
-    ASSERT(functionExecutable->inherits(FunctionExecutable::info()));
     VM& vm = exec->vm();
+    ASSERT(functionExecutable->inherits(vm, FunctionExecutable::info()));
     NativeCallFrameTracer tracer(&vm, exec);
-    return JSValue::encode(JSFunction::create(vm, static_cast<FunctionExecutable*>(functionExecutable), exec->scope()));
+    if (isInvalidated)
+        return JSValue::encode(FunctionType::createWithInvalidatedReallocationWatchpoint(vm, static_cast<FunctionExecutable*>(functionExecutable), scope));
+    return JSValue::encode(FunctionType::create(vm, static_cast<FunctionExecutable*>(functionExecutable), scope));
+}
+
+extern "C" {
+
+EncodedJSValue JIT_OPERATION operationNewFunction(ExecState* exec, JSScope* scope, JSCell* functionExecutable)
+{
+    return operationNewFunctionCommon<JSFunction>(exec, scope, functionExecutable, false);
+}
+
+EncodedJSValue JIT_OPERATION operationNewFunctionWithInvalidatedReallocationWatchpoint(ExecState* exec, JSScope* scope, JSCell* functionExecutable)
+{
+    return operationNewFunctionCommon<JSFunction>(exec, scope, functionExecutable, true);
+}
+
+EncodedJSValue JIT_OPERATION operationNewGeneratorFunction(ExecState* exec, JSScope* scope, JSCell* functionExecutable)
+{
+    return operationNewFunctionCommon<JSGeneratorFunction>(exec, scope, functionExecutable, false);
+}
+
+EncodedJSValue JIT_OPERATION operationNewGeneratorFunctionWithInvalidatedReallocationWatchpoint(ExecState* exec, JSScope* scope, JSCell* functionExecutable)
+{
+    return operationNewFunctionCommon<JSGeneratorFunction>(exec, scope, functionExecutable, true);
+}
+
+EncodedJSValue JIT_OPERATION operationNewAsyncFunction(ExecState* exec, JSScope* scope, JSCell* functionExecutable)
+{
+    return operationNewFunctionCommon<JSAsyncFunction>(exec, scope, functionExecutable, false);
+}
+
+EncodedJSValue JIT_OPERATION operationNewAsyncFunctionWithInvalidatedReallocationWatchpoint(ExecState* exec, JSScope* scope, JSCell* functionExecutable)
+{
+    return operationNewFunctionCommon<JSAsyncFunction>(exec, scope, functionExecutable, true);
+}
+
+void JIT_OPERATION operationSetFunctionName(ExecState* exec, JSCell* funcCell, EncodedJSValue encodedName)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    JSFunction* func = jsCast<JSFunction*>(funcCell);
+    JSValue name = JSValue::decode(encodedName);
+    func->setFunctionName(exec, name);
 }
 
 JSCell* JIT_OPERATION operationNewObject(ExecState* exec, Structure* structure)
 {
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
-    
+
     return constructEmptyObject(exec, structure);
 }
 
 EncodedJSValue JIT_OPERATION operationNewRegexp(ExecState* exec, void* regexpPtr)
 {
+    SuperSamplerScope superSamplerScope(false);
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
+    auto scope = DECLARE_THROW_SCOPE(vm);
+
     RegExp* regexp = static_cast<RegExp*>(regexpPtr);
     if (!regexp->isValid()) {
-        vm.throwException(exec, createSyntaxError(exec, "Invalid flags supplied to RegExp constructor."));
+        throwException(exec, scope, createSyntaxError(exec, regexp->errorMessage()));
         return JSValue::encode(jsUndefined());
     }
 
     return JSValue::encode(RegExpObject::create(vm, exec->lexicalGlobalObject()->regExpStructure(), regexp));
 }
 
-void JIT_OPERATION operationHandleWatchdogTimer(ExecState* exec)
+// The only reason for returning an UnusedPtr (instead of void) is so that we can reuse the
+// existing DFG slow path generator machinery when creating the slow path for CheckWatchdogTimer
+// in the DFG. If a DFG slow path generator that supports a void return type is added in the
+// future, we can switch to using that then.
+UnusedPtr JIT_OPERATION operationHandleWatchdogTimer(ExecState* exec)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
+    auto scope = DECLARE_THROW_SCOPE(vm);
+
+    if (UNLIKELY(vm.shouldTriggerTermination(exec)))
+        throwException(exec, scope, createTerminatedExecutionException(&vm));
 
-    if (UNLIKELY(vm.watchdog.didFire(exec)))
-        vm.throwException(exec, createTerminatedExecutionException(&vm));
+    return nullptr;
 }
 
-void JIT_OPERATION operationThrowStaticError(ExecState* exec, EncodedJSValue encodedValue, int32_t referenceErrorFlag)
+void JIT_OPERATION operationDebug(ExecState* exec, int32_t debugHookType)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
 
-    String message = errorDescriptionForValue(exec, JSValue::decode(encodedValue))->value(exec);
-    if (referenceErrorFlag)
-        vm.throwException(exec, createReferenceError(exec, message));
-    else
-        vm.throwException(exec, createTypeError(exec, message));
+    vm.interpreter->debug(exec, static_cast<DebugHookType>(debugHookType));
 }
 
-void JIT_OPERATION operationDebug(ExecState* exec, int32_t debugHookID)
+#if ENABLE(DFG_JIT)
+static void updateAllPredictionsAndOptimizeAfterWarmUp(CodeBlock* codeBlock)
 {
-    VM& vm = exec->vm();
-    NativeCallFrameTracer tracer(&vm, exec);
-
-    vm.interpreter->debug(exec, static_cast<DebugHookID>(debugHookID));
+    codeBlock->updateAllPredictions();
+    codeBlock->optimizeAfterWarmUp();
 }
 
-#if ENABLE(DFG_JIT)
-char* JIT_OPERATION operationOptimize(ExecState* exec, int32_t bytecodeIndex)
+SlowPathReturnType JIT_OPERATION operationOptimize(ExecState* exec, int32_t bytecodeIndex)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
@@ -996,7 +1257,11 @@ char* JIT_OPERATION operationOptimize(ExecState* exec, int32_t bytecodeIndex)
     DeferGCForAWhile deferGC(vm.heap);
     
     CodeBlock* codeBlock = exec->codeBlock();
-
+    if (codeBlock->jitType() != JITCode::BaselineJIT) {
+        dataLog("Unexpected code block in Baseline->DFG tier-up: ", *codeBlock, "\n");
+        RELEASE_ASSERT_NOT_REACHED();
+    }
+    
     if (bytecodeIndex) {
         // If we're attempting to OSR from a loop, assume that this should be
         // separately optimized.
@@ -1017,29 +1282,38 @@ char* JIT_OPERATION operationOptimize(ExecState* exec, int32_t bytecodeIndex)
     }
 
     if (!codeBlock->checkIfOptimizationThresholdReached()) {
+        CODEBLOCK_LOG_EVENT(codeBlock, "delayOptimizeToDFG", ("counter = ", codeBlock->jitExecuteCounter()));
         codeBlock->updateAllPredictions();
         if (Options::verboseOSR())
             dataLog("Choosing not to optimize ", *codeBlock, " yet, because the threshold hasn't been reached.\n");
-        return 0;
+        return encodeResult(0, 0);
     }
     
+    Debugger* debugger = codeBlock->globalObject()->debugger();
+    if (debugger && (debugger->isStepping() || codeBlock->baselineAlternative()->hasDebuggerRequests())) {
+        CODEBLOCK_LOG_EVENT(codeBlock, "delayOptimizeToDFG", ("debugger is stepping or has requests"));
+        updateAllPredictionsAndOptimizeAfterWarmUp(codeBlock);
+        return encodeResult(0, 0);
+    }
+
     if (codeBlock->m_shouldAlwaysBeInlined) {
-        codeBlock->updateAllPredictions();
-        codeBlock->optimizeAfterWarmUp();
+        CODEBLOCK_LOG_EVENT(codeBlock, "delayOptimizeToDFG", ("should always be inlined"));
+        updateAllPredictionsAndOptimizeAfterWarmUp(codeBlock);
         if (Options::verboseOSR())
             dataLog("Choosing not to optimize ", *codeBlock, " yet, because m_shouldAlwaysBeInlined == true.\n");
-        return 0;
+        return encodeResult(0, 0);
     }
 
     // We cannot be in the process of asynchronous compilation and also have an optimized
     // replacement.
+    DFG::Worklist* worklist = DFG::existingGlobalDFGWorklistOrNull();
     ASSERT(
-        !vm.worklist
-        || !(vm.worklist->compilationState(DFG::CompilationKey(codeBlock, DFG::DFGMode)) != DFG::Worklist::NotKnown
+        !worklist
+        || !(worklist->compilationState(DFG::CompilationKey(codeBlock, DFG::DFGMode)) != DFG::Worklist::NotKnown
         && codeBlock->hasOptimizedReplacement()));
 
     DFG::Worklist::State worklistState;
-    if (vm.worklist) {
+    if (worklist) {
         // The call to DFG::Worklist::completeAllReadyPlansForVM() will complete all ready
         // (i.e. compiled) code blocks. But if it completes ours, we also need to know
         // what the result was so that we don't plow ahead and attempt OSR or immediate
@@ -1058,17 +1332,18 @@ char* JIT_OPERATION operationOptimize(ExecState* exec, int32_t bytecodeIndex)
         // probably a waste of memory. Our goal here is to complete code blocks as soon as
         // possible in order to minimize the chances of us executing baseline code after
         // optimized code is already available.
-        worklistState = vm.worklist->completeAllReadyPlansForVM(
+        worklistState = worklist->completeAllReadyPlansForVM(
             vm, DFG::CompilationKey(codeBlock, DFG::DFGMode));
     } else
         worklistState = DFG::Worklist::NotKnown;
 
     if (worklistState == DFG::Worklist::Compiling) {
+        CODEBLOCK_LOG_EVENT(codeBlock, "delayOptimizeToDFG", ("compiling"));
         // We cannot be in the process of asynchronous compilation and also have an optimized
         // replacement.
         RELEASE_ASSERT(!codeBlock->hasOptimizedReplacement());
         codeBlock->setOptimizationThresholdBasedOnCompilationResult(CompilationDeferred);
-        return 0;
+        return encodeResult(0, 0);
     }
 
     if (worklistState == DFG::Worklist::Compiled) {
@@ -1078,10 +1353,11 @@ char* JIT_OPERATION operationOptimize(ExecState* exec, int32_t bytecodeIndex)
         // CodeBlock::setOptimizationThresholdBasedOnCompilationResult() and we have
         // nothing left to do.
         if (!codeBlock->hasOptimizedReplacement()) {
+            CODEBLOCK_LOG_EVENT(codeBlock, "delayOptimizeToDFG", ("compiled and failed"));
             codeBlock->updateAllPredictions();
             if (Options::verboseOSR())
                 dataLog("Code block ", *codeBlock, " was compiled but it doesn't have an optimized replacement.\n");
-            return 0;
+            return encodeResult(0, 0);
         }
     } else if (codeBlock->hasOptimizedReplacement()) {
         if (Options::verboseOSR())
@@ -1100,22 +1376,24 @@ char* JIT_OPERATION operationOptimize(ExecState* exec, int32_t bytecodeIndex)
         // shouldReoptimizeFromLoopNow() to always return true. But we make it do some
         // additional checking anyway, to reduce the amount of recompilation thrashing.
         if (codeBlock->replacement()->shouldReoptimizeFromLoopNow()) {
+            CODEBLOCK_LOG_EVENT(codeBlock, "delayOptimizeToDFG", ("should reoptimize from loop now"));
             if (Options::verboseOSR()) {
                 dataLog(
                     "Triggering reoptimization of ", *codeBlock,
                     "(", *codeBlock->replacement(), ") (in loop).\n");
             }
-            codeBlock->replacement()->jettison(CountReoptimization);
-            return 0;
+            codeBlock->replacement()->jettison(Profiler::JettisonDueToBaselineLoopReoptimizationTrigger, CountReoptimization);
+            return encodeResult(0, 0);
         }
     } else {
         if (!codeBlock->shouldOptimizeNow()) {
+            CODEBLOCK_LOG_EVENT(codeBlock, "delayOptimizeToDFG", ("insufficient profiling"));
             if (Options::verboseOSR()) {
                 dataLog(
                     "Delaying optimization for ", *codeBlock,
                     " because of insufficient profiling.\n");
             }
-            return 0;
+            return encodeResult(0, 0);
         }
 
         if (Options::verboseOSR())
@@ -1123,46 +1401,42 @@ char* JIT_OPERATION operationOptimize(ExecState* exec, int32_t bytecodeIndex)
 
         unsigned numVarsWithValues;
         if (bytecodeIndex)
-            numVarsWithValues = codeBlock->m_numVars;
+            numVarsWithValues = codeBlock->m_numCalleeLocals;
         else
             numVarsWithValues = 0;
         Operands<JSValue> mustHandleValues(codeBlock->numParameters(), numVarsWithValues);
+        int localsUsedForCalleeSaves = static_cast<int>(CodeBlock::llintBaselineCalleeSaveSpaceAsVirtualRegisters());
         for (size_t i = 0; i < mustHandleValues.size(); ++i) {
             int operand = mustHandleValues.operandForIndex(i);
-            if (operandIsArgument(operand)
-                && !VirtualRegister(operand).toArgument()
-                && codeBlock->codeType() == FunctionCode
-                && codeBlock->specializationKind() == CodeForConstruct) {
-                // Ugh. If we're in a constructor, the 'this' argument may hold garbage. It will
-                // also never be used. It doesn't matter what we put into the value for this,
-                // but it has to be an actual value that can be grokked by subsequent DFG passes,
-                // so we sanitize it here by turning it into Undefined.
-                mustHandleValues[i] = jsUndefined();
-            } else
-                mustHandleValues[i] = exec->uncheckedR(operand).jsValue();
+            if (operandIsLocal(operand) && VirtualRegister(operand).toLocal() < localsUsedForCalleeSaves)
+                continue;
+            mustHandleValues[i] = exec->uncheckedR(operand).jsValue();
         }
 
+        CodeBlock* replacementCodeBlock = codeBlock->newReplacement();
         CompilationResult result = DFG::compile(
-            vm, codeBlock->newReplacement().get(), DFG::DFGMode, bytecodeIndex,
-            mustHandleValues, JITToDFGDeferredCompilationCallback::create(),
-            vm.ensureWorklist());
+            vm, replacementCodeBlock, nullptr, DFG::DFGMode, bytecodeIndex,
+            mustHandleValues, JITToDFGDeferredCompilationCallback::create());
         
-        if (result != CompilationSuccessful)
-            return 0;
+        if (result != CompilationSuccessful) {
+            CODEBLOCK_LOG_EVENT(codeBlock, "delayOptimizeToDFG", ("compilation failed"));
+            return encodeResult(0, 0);
+        }
     }
     
     CodeBlock* optimizedCodeBlock = codeBlock->replacement();
     ASSERT(JITCode::isOptimizingJIT(optimizedCodeBlock->jitType()));
     
-    if (void* address = DFG::prepareOSREntry(exec, optimizedCodeBlock, bytecodeIndex)) {
+    if (void* dataBuffer = DFG::prepareOSREntry(exec, optimizedCodeBlock, bytecodeIndex)) {
+        CODEBLOCK_LOG_EVENT(optimizedCodeBlock, "osrEntry", ("at bc#", bytecodeIndex));
         if (Options::verboseOSR()) {
             dataLog(
-                "Performing OSR ", *codeBlock, " -> ", *optimizedCodeBlock, ", address ",
-                RawPointer(OUR_RETURN_ADDRESS), " -> ", RawPointer(address), ".\n");
+                "Performing OSR ", *codeBlock, " -> ", *optimizedCodeBlock, ".\n");
         }
 
         codeBlock->optimizeSoon();
-        return static_cast<char*>(address);
+        codeBlock->unlinkedCodeBlock()->setDidOptimize(TrueTriState);
+        return encodeResult(vm.getCTIStub(DFG::osrEntryThunkGenerator).code().executableAddress(), dataBuffer);
     }
 
     if (Options::verboseOSR()) {
@@ -1185,20 +1459,22 @@ char* JIT_OPERATION operationOptimize(ExecState* exec, int32_t bytecodeIndex)
     // right now. So, we only trigger reoptimization only upon the more conservative (non-loop)
     // reoptimization trigger.
     if (optimizedCodeBlock->shouldReoptimizeNow()) {
+        CODEBLOCK_LOG_EVENT(codeBlock, "delayOptimizeToDFG", ("should reoptimize now"));
         if (Options::verboseOSR()) {
             dataLog(
                 "Triggering reoptimization of ", *codeBlock, " -> ",
                 *codeBlock->replacement(), " (after OSR fail).\n");
         }
-        optimizedCodeBlock->jettison(CountReoptimization);
-        return 0;
+        optimizedCodeBlock->jettison(Profiler::JettisonDueToBaselineLoopReoptimizationTriggerOnOSREntryFail, CountReoptimization);
+        return encodeResult(0, 0);
     }
 
     // OSR failed this time, but it might succeed next time! Let the code run a bit
     // longer and then try again.
     codeBlock->optimizeAfterWarmUp();
     
-    return 0;
+    CODEBLOCK_LOG_EVENT(codeBlock, "delayOptimizeToDFG", ("OSR failed"));
+    return encodeResult(0, 0);
 }
 #endif
 
@@ -1212,31 +1488,25 @@ void JIT_OPERATION operationPutByIndex(ExecState* exec, EncodedJSValue encodedAr
     asArray(arrayValue)->putDirectIndex(exec, index, JSValue::decode(encodedValue));
 }
 
-#if USE(JSVALUE64)
-void JIT_OPERATION operationPutGetterSetter(ExecState* exec, EncodedJSValue encodedObjectValue, Identifier* identifier, EncodedJSValue encodedGetterValue, EncodedJSValue encodedSetterValue)
+enum class AccessorType {
+    Getter,
+    Setter
+};
+
+static void putAccessorByVal(ExecState* exec, JSObject* base, JSValue subscript, int32_t attribute, JSObject* accessor, AccessorType accessorType)
 {
     VM& vm = exec->vm();
-    NativeCallFrameTracer tracer(&vm, exec);
-
-    ASSERT(JSValue::decode(encodedObjectValue).isObject());
-    JSObject* baseObj = asObject(JSValue::decode(encodedObjectValue));
-
-    GetterSetter* accessor = GetterSetter::create(vm);
-
-    JSValue getter = JSValue::decode(encodedGetterValue);
-    JSValue setter = JSValue::decode(encodedSetterValue);
-    ASSERT(getter.isObject() || getter.isUndefined());
-    ASSERT(setter.isObject() || setter.isUndefined());
-    ASSERT(getter.isObject() || setter.isObject());
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    auto propertyKey = subscript.toPropertyKey(exec);
+    RETURN_IF_EXCEPTION(scope, void());
 
-    if (!getter.isUndefined())
-        accessor->setGetter(vm, asObject(getter));
-    if (!setter.isUndefined())
-        accessor->setSetter(vm, asObject(setter));
-    baseObj->putDirectAccessor(exec, *identifier, accessor, Accessor);
+    if (accessorType == AccessorType::Getter)
+        base->putGetter(exec, propertyKey, accessor, attribute);
+    else
+        base->putSetter(exec, propertyKey, accessor, attribute);
 }
-#else
-void JIT_OPERATION operationPutGetterSetter(ExecState* exec, JSCell* object, Identifier* identifier, JSCell* getter, JSCell* setter)
+
+void JIT_OPERATION operationPutGetterById(ExecState* exec, JSCell* object, UniquedStringImpl* uid, int32_t options, JSCell* getter)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
@@ -1244,208 +1514,372 @@ void JIT_OPERATION operationPutGetterSetter(ExecState* exec, JSCell* object, Ide
     ASSERT(object && object->isObject());
     JSObject* baseObj = object->getObject();
 
-    GetterSetter* accessor = GetterSetter::create(vm);
-
-    ASSERT(!getter || getter->isObject());
-    ASSERT(!setter || setter->isObject());
-    ASSERT(getter || setter);
-
-    if (getter)
-        accessor->setGetter(vm, getter->getObject());
-    if (setter)
-        accessor->setSetter(vm, setter->getObject());
-    baseObj->putDirectAccessor(exec, *identifier, accessor, Accessor);
+    ASSERT(getter->isObject());
+    baseObj->putGetter(exec, uid, getter, options);
 }
-#endif
 
-void JIT_OPERATION operationPushNameScope(ExecState* exec, Identifier* identifier, EncodedJSValue encodedValue, int32_t attibutes)
+void JIT_OPERATION operationPutSetterById(ExecState* exec, JSCell* object, UniquedStringImpl* uid, int32_t options, JSCell* setter)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
 
-    JSNameScope* scope = JSNameScope::create(exec, *identifier, JSValue::decode(encodedValue), attibutes);
+    ASSERT(object && object->isObject());
+    JSObject* baseObj = object->getObject();
 
-    exec->setScope(scope);
+    ASSERT(setter->isObject());
+    baseObj->putSetter(exec, uid, setter, options);
 }
 
-void JIT_OPERATION operationPushWithScope(ExecState* exec, EncodedJSValue encodedValue)
+void JIT_OPERATION operationPutGetterByVal(ExecState* exec, JSCell* base, EncodedJSValue encodedSubscript, int32_t attribute, JSCell* getter)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
 
-    JSObject* o = JSValue::decode(encodedValue).toObject(exec);
-    if (vm.exception())
-        return;
-
-    exec->setScope(JSWithScope::create(exec, o));
+    putAccessorByVal(exec, asObject(base), JSValue::decode(encodedSubscript), attribute, asObject(getter), AccessorType::Getter);
 }
 
-void JIT_OPERATION operationPopScope(ExecState* exec)
+void JIT_OPERATION operationPutSetterByVal(ExecState* exec, JSCell* base, EncodedJSValue encodedSubscript, int32_t attribute, JSCell* setter)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
 
-    exec->setScope(exec->scope()->next());
+    putAccessorByVal(exec, asObject(base), JSValue::decode(encodedSubscript), attribute, asObject(setter), AccessorType::Setter);
 }
 
-void JIT_OPERATION operationProfileDidCall(ExecState* exec, EncodedJSValue encodedValue)
+#if USE(JSVALUE64)
+void JIT_OPERATION operationPutGetterSetter(ExecState* exec, JSCell* object, UniquedStringImpl* uid, int32_t attribute, EncodedJSValue encodedGetterValue, EncodedJSValue encodedSetterValue)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
 
-    if (LegacyProfiler* profiler = vm.enabledProfiler())
-        profiler->didExecute(exec, JSValue::decode(encodedValue));
+    ASSERT(object && object->isObject());
+    JSObject* baseObj = asObject(object);
+
+    GetterSetter* accessor = GetterSetter::create(vm, exec->lexicalGlobalObject());
+
+    JSValue getter = JSValue::decode(encodedGetterValue);
+    JSValue setter = JSValue::decode(encodedSetterValue);
+    ASSERT(getter.isObject() || getter.isUndefined());
+    ASSERT(setter.isObject() || setter.isUndefined());
+    ASSERT(getter.isObject() || setter.isObject());
+
+    if (!getter.isUndefined())
+        accessor->setGetter(vm, exec->lexicalGlobalObject(), asObject(getter));
+    if (!setter.isUndefined())
+        accessor->setSetter(vm, exec->lexicalGlobalObject(), asObject(setter));
+    baseObj->putDirectAccessor(exec, uid, accessor, attribute);
 }
 
-void JIT_OPERATION operationProfileWillCall(ExecState* exec, EncodedJSValue encodedValue)
+#else
+void JIT_OPERATION operationPutGetterSetter(ExecState* exec, JSCell* object, UniquedStringImpl* uid, int32_t attribute, JSCell* getter, JSCell* setter)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
 
-    if (LegacyProfiler* profiler = vm.enabledProfiler())
-        profiler->willExecute(exec, JSValue::decode(encodedValue));
-}
+    ASSERT(object && object->isObject());
+    JSObject* baseObj = asObject(object);
 
-EncodedJSValue JIT_OPERATION operationCheckHasInstance(ExecState* exec, EncodedJSValue encodedValue, EncodedJSValue encodedBaseVal)
-{
-    VM* vm = &exec->vm();
-    NativeCallFrameTracer tracer(vm, exec);
+    GetterSetter* accessor = GetterSetter::create(vm, exec->lexicalGlobalObject());
 
-    JSValue value = JSValue::decode(encodedValue);
-    JSValue baseVal = JSValue::decode(encodedBaseVal);
-
-    if (baseVal.isObject()) {
-        JSObject* baseObject = asObject(baseVal);
-        ASSERT(!baseObject->structure()->typeInfo().implementsDefaultHasInstance());
-        if (baseObject->structure()->typeInfo().implementsHasInstance()) {
-            bool result = baseObject->methodTable()->customHasInstance(baseObject, exec, value);
-            return JSValue::encode(jsBoolean(result));
-        }
-    }
+    ASSERT(!getter || getter->isObject());
+    ASSERT(!setter || setter->isObject());
+    ASSERT(getter || setter);
 
-    vm->throwException(exec, createInvalidParameterError(exec, "instanceof", baseVal));
-    return JSValue::encode(JSValue());
+    if (getter)
+        accessor->setGetter(vm, exec->lexicalGlobalObject(), getter->getObject());
+    if (setter)
+        accessor->setSetter(vm, exec->lexicalGlobalObject(), setter->getObject());
+    baseObj->putDirectAccessor(exec, uid, accessor, attribute);
 }
+#endif
 
-JSCell* JIT_OPERATION operationCreateActivation(ExecState* exec, int32_t offset)
+void JIT_OPERATION operationPopScope(ExecState* exec, int32_t scopeReg)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
-    JSActivation* activation = JSActivation::create(vm, exec, exec->registers() + offset, exec->codeBlock());
-    exec->setScope(activation);
-    return activation;
+
+    JSScope* scope = exec->uncheckedR(scopeReg).Register::scope();
+    exec->uncheckedR(scopeReg) = scope->next();
 }
 
-JSCell* JIT_OPERATION operationCreateArguments(ExecState* exec)
+int32_t JIT_OPERATION operationInstanceOfCustom(ExecState* exec, EncodedJSValue encodedValue, JSObject* constructor, EncodedJSValue encodedHasInstance)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
-    // NB: This needs to be exceedingly careful with top call frame tracking, since it
-    // may be called from OSR exit, while the state of the call stack is bizarre.
-    Arguments* result = Arguments::create(vm, exec);
-    ASSERT(!vm.exception());
-    return result;
+
+    JSValue value = JSValue::decode(encodedValue);
+    JSValue hasInstanceValue = JSValue::decode(encodedHasInstance);
+
+    ASSERT(hasInstanceValue != exec->lexicalGlobalObject()->functionProtoHasInstanceSymbolFunction() || !constructor->structure()->typeInfo().implementsDefaultHasInstance());
+
+    if (constructor->hasInstance(exec, value, hasInstanceValue))
+        return 1;
+    return 0;
 }
 
-EncodedJSValue JIT_OPERATION operationGetArgumentsLength(ExecState* exec, int32_t argumentsRegister)
-{
-    VM& vm = exec->vm();
-    NativeCallFrameTracer tracer(&vm, exec);
-    // Here we can assume that the argumernts were created. Because otherwise the JIT code would
-    // have not made this call.
-    Identifier ident(&vm, "length");
-    JSValue baseValue = exec->uncheckedR(argumentsRegister).jsValue();
-    PropertySlot slot(baseValue);
-    return JSValue::encode(baseValue.get(exec, ident, slot));
 }
 
+static bool canAccessArgumentIndexQuickly(JSObject& object, uint32_t index)
+{
+    switch (object.structure()->typeInfo().type()) {
+    case DirectArgumentsType: {
+        DirectArguments* directArguments = jsCast<DirectArguments*>(&object);
+        if (directArguments->isMappedArgumentInDFG(index))
+            return true;
+        break;
+    }
+    case ScopedArgumentsType: {
+        ScopedArguments* scopedArguments = jsCast<ScopedArguments*>(&object);
+        if (scopedArguments->isMappedArgumentInDFG(index))
+            return true;
+        break;
+    }
+    default:
+        break;
+    }
+    return false;
 }
 
-static JSValue getByVal(ExecState* exec, JSValue baseValue, JSValue subscript, ReturnAddressPtr returnAddress)
+static JSValue getByVal(ExecState* exec, JSValue baseValue, JSValue subscript, ByValInfo* byValInfo, ReturnAddressPtr returnAddress)
 {
+    VM& vm = exec->vm();
+    auto scope = DECLARE_THROW_SCOPE(vm);
+
     if (LIKELY(baseValue.isCell() && subscript.isString())) {
-        if (JSValue result = baseValue.asCell()->fastGetOwnProperty(exec, asString(subscript)->value(exec)))
-            return result;
+        Structure& structure = *baseValue.asCell()->structure(vm);
+        if (JSCell::canUseFastGetOwnProperty(structure)) {
+            if (RefPtr<AtomicStringImpl> existingAtomicString = asString(subscript)->toExistingAtomicString(exec)) {
+                if (JSValue result = baseValue.asCell()->fastGetOwnProperty(vm, structure, existingAtomicString.get())) {
+                    ASSERT(exec->bytecodeOffset());
+                    if (byValInfo->stubInfo && byValInfo->cachedId.impl() != existingAtomicString)
+                        byValInfo->tookSlowPath = true;
+                    return result;
+                }
+            }
+        }
     }
 
     if (subscript.isUInt32()) {
+        ASSERT(exec->bytecodeOffset());
+        byValInfo->tookSlowPath = true;
+
         uint32_t i = subscript.asUInt32();
-        if (isJSString(baseValue) && asString(baseValue)->canGetIndex(i)) {
-            ctiPatchCallByReturnAddress(exec->codeBlock(), returnAddress, FunctionPtr(operationGetByValString));
-            return asString(baseValue)->getIndex(exec, i);
+        if (isJSString(baseValue)) {
+            if (asString(baseValue)->canGetIndex(i)) {
+                ctiPatchCallByReturnAddress(returnAddress, FunctionPtr(operationGetByValString));
+                return asString(baseValue)->getIndex(exec, i);
+            }
+            byValInfo->arrayProfile->setOutOfBounds();
+        } else if (baseValue.isObject()) {
+            JSObject* object = asObject(baseValue);
+            if (object->canGetIndexQuickly(i))
+                return object->getIndexQuickly(i);
+
+            if (!canAccessArgumentIndexQuickly(*object, i)) {
+                // FIXME: This will make us think that in-bounds typed array accesses are actually
+                // out-of-bounds.
+                // https://bugs.webkit.org/show_bug.cgi?id=149886
+                byValInfo->arrayProfile->setOutOfBounds();
+            }
         }
+
         return baseValue.get(exec, i);
     }
 
-    if (isName(subscript))
-        return baseValue.get(exec, jsCast<NameInstance*>(subscript.asCell())->privateName());
+    baseValue.requireObjectCoercible(exec);
+    RETURN_IF_EXCEPTION(scope, JSValue());
+    auto property = subscript.toPropertyKey(exec);
+    RETURN_IF_EXCEPTION(scope, JSValue());
+
+    ASSERT(exec->bytecodeOffset());
+    if (byValInfo->stubInfo && (!isStringOrSymbol(subscript) || byValInfo->cachedId != property))
+        byValInfo->tookSlowPath = true;
 
-    Identifier property(exec, subscript.toString(exec)->value(exec));
     return baseValue.get(exec, property);
 }
 
+static OptimizationResult tryGetByValOptimize(ExecState* exec, JSValue baseValue, JSValue subscript, ByValInfo* byValInfo, ReturnAddressPtr returnAddress)
+{
+    // See if it's worth optimizing this at all.
+    OptimizationResult optimizationResult = OptimizationResult::NotOptimized;
+
+    VM& vm = exec->vm();
+
+    if (baseValue.isObject() && subscript.isInt32()) {
+        JSObject* object = asObject(baseValue);
+
+        ASSERT(exec->bytecodeOffset());
+        ASSERT(!byValInfo->stubRoutine);
+
+        if (hasOptimizableIndexing(object->structure(vm))) {
+            // Attempt to optimize.
+            Structure* structure = object->structure(vm);
+            JITArrayMode arrayMode = jitArrayModeForStructure(structure);
+            if (arrayMode != byValInfo->arrayMode) {
+                // If we reached this case, we got an interesting array mode we did not expect when we compiled.
+                // Let's update the profile to do better next time.
+                CodeBlock* codeBlock = exec->codeBlock();
+                ConcurrentJSLocker locker(codeBlock->m_lock);
+                byValInfo->arrayProfile->computeUpdatedPrediction(locker, codeBlock, structure);
+
+                JIT::compileGetByVal(&vm, exec->codeBlock(), byValInfo, returnAddress, arrayMode);
+                optimizationResult = OptimizationResult::Optimized;
+            }
+        }
+
+        // If we failed to patch and we have some object that intercepts indexed get, then don't even wait until 10 times.
+        if (optimizationResult != OptimizationResult::Optimized && object->structure(vm)->typeInfo().interceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero())
+            optimizationResult = OptimizationResult::GiveUp;
+    }
+
+    if (baseValue.isObject() && isStringOrSymbol(subscript)) {
+        const Identifier propertyName = subscript.toPropertyKey(exec);
+        if (subscript.isSymbol() || !parseIndex(propertyName)) {
+            ASSERT(exec->bytecodeOffset());
+            ASSERT(!byValInfo->stubRoutine);
+            if (byValInfo->seen) {
+                if (byValInfo->cachedId == propertyName) {
+                    JIT::compileGetByValWithCachedId(&vm, exec->codeBlock(), byValInfo, returnAddress, propertyName);
+                    optimizationResult = OptimizationResult::Optimized;
+                } else {
+                    // Seem like a generic property access site.
+                    optimizationResult = OptimizationResult::GiveUp;
+                }
+            } else {
+                CodeBlock* codeBlock = exec->codeBlock();
+                ConcurrentJSLocker locker(codeBlock->m_lock);
+                byValInfo->seen = true;
+                byValInfo->cachedId = propertyName;
+                if (subscript.isSymbol())
+                    byValInfo->cachedSymbol.set(vm, codeBlock, asSymbol(subscript));
+                optimizationResult = OptimizationResult::SeenOnce;
+            }
+        }
+    }
+
+    if (optimizationResult != OptimizationResult::Optimized && optimizationResult != OptimizationResult::SeenOnce) {
+        // If we take slow path more than 10 times without patching then make sure we
+        // never make that mistake again. For cases where we see non-index-intercepting
+        // objects, this gives 10 iterations worth of opportunity for us to observe
+        // that the get_by_val may be polymorphic. We count up slowPathCount even if
+        // the result is GiveUp.
+        if (++byValInfo->slowPathCount >= 10)
+            optimizationResult = OptimizationResult::GiveUp;
+    }
+
+    return optimizationResult;
+}
+
 extern "C" {
-    
-EncodedJSValue JIT_OPERATION operationGetByValGeneric(ExecState* exec, EncodedJSValue encodedBase, EncodedJSValue encodedSubscript)
+
+EncodedJSValue JIT_OPERATION operationGetByValGeneric(ExecState* exec, EncodedJSValue encodedBase, EncodedJSValue encodedSubscript, ByValInfo* byValInfo)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
     JSValue baseValue = JSValue::decode(encodedBase);
     JSValue subscript = JSValue::decode(encodedSubscript);
 
-    JSValue result = getByVal(exec, baseValue, subscript, ReturnAddressPtr(OUR_RETURN_ADDRESS));
+    JSValue result = getByVal(exec, baseValue, subscript, byValInfo, ReturnAddressPtr(OUR_RETURN_ADDRESS));
     return JSValue::encode(result);
 }
 
-EncodedJSValue JIT_OPERATION operationGetByValDefault(ExecState* exec, EncodedJSValue encodedBase, EncodedJSValue encodedSubscript)
+EncodedJSValue JIT_OPERATION operationGetByValOptimize(ExecState* exec, EncodedJSValue encodedBase, EncodedJSValue encodedSubscript, ByValInfo* byValInfo)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+
+    JSValue baseValue = JSValue::decode(encodedBase);
+    JSValue subscript = JSValue::decode(encodedSubscript);
+    ReturnAddressPtr returnAddress = ReturnAddressPtr(OUR_RETURN_ADDRESS);
+    if (tryGetByValOptimize(exec, baseValue, subscript, byValInfo, returnAddress) == OptimizationResult::GiveUp) {
+        // Don't ever try to optimize.
+        byValInfo->tookSlowPath = true;
+        ctiPatchCallByReturnAddress(returnAddress, FunctionPtr(operationGetByValGeneric));
+    }
+
+    return JSValue::encode(getByVal(exec, baseValue, subscript, byValInfo, returnAddress));
+}
+
+EncodedJSValue JIT_OPERATION operationHasIndexedPropertyDefault(ExecState* exec, EncodedJSValue encodedBase, EncodedJSValue encodedSubscript, ByValInfo* byValInfo)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
     JSValue baseValue = JSValue::decode(encodedBase);
     JSValue subscript = JSValue::decode(encodedSubscript);
     
-    if (baseValue.isObject() && subscript.isInt32()) {
-        // See if it's worth optimizing this at all.
-        JSObject* object = asObject(baseValue);
-        bool didOptimize = false;
+    ASSERT(baseValue.isObject());
+    ASSERT(subscript.isUInt32());
 
-        unsigned bytecodeOffset = exec->locationAsBytecodeOffset();
-        ASSERT(bytecodeOffset);
-        ByValInfo& byValInfo = exec->codeBlock()->getByValInfo(bytecodeOffset - 1);
-        ASSERT(!byValInfo.stubRoutine);
-        
-        if (hasOptimizableIndexing(object->structure())) {
-            // Attempt to optimize.
-            JITArrayMode arrayMode = jitArrayModeForStructure(object->structure());
-            if (arrayMode != byValInfo.arrayMode) {
-                JIT::compileGetByVal(&vm, exec->codeBlock(), &byValInfo, ReturnAddressPtr(OUR_RETURN_ADDRESS), arrayMode);
-                didOptimize = true;
-            }
+    JSObject* object = asObject(baseValue);
+    bool didOptimize = false;
+
+    ASSERT(exec->bytecodeOffset());
+    ASSERT(!byValInfo->stubRoutine);
+    
+    if (hasOptimizableIndexing(object->structure(vm))) {
+        // Attempt to optimize.
+        JITArrayMode arrayMode = jitArrayModeForStructure(object->structure(vm));
+        if (arrayMode != byValInfo->arrayMode) {
+            JIT::compileHasIndexedProperty(&vm, exec->codeBlock(), byValInfo, ReturnAddressPtr(OUR_RETURN_ADDRESS), arrayMode);
+            didOptimize = true;
         }
-        
-        if (!didOptimize) {
-            // If we take slow path more than 10 times without patching then make sure we
-            // never make that mistake again. Or, if we failed to patch and we have some object
-            // that intercepts indexed get, then don't even wait until 10 times. For cases
-            // where we see non-index-intercepting objects, this gives 10 iterations worth of
-            // opportunity for us to observe that the get_by_val may be polymorphic.
-            if (++byValInfo.slowPathCount >= 10
-                || object->structure()->typeInfo().interceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero()) {
-                // Don't ever try to optimize.
-                RepatchBuffer repatchBuffer(exec->codeBlock());
-                repatchBuffer.relinkCallerToFunction(ReturnAddressPtr(OUR_RETURN_ADDRESS), FunctionPtr(operationGetByValGeneric));
-            }
+    }
+    
+    if (!didOptimize) {
+        // If we take slow path more than 10 times without patching then make sure we
+        // never make that mistake again. Or, if we failed to patch and we have some object
+        // that intercepts indexed get, then don't even wait until 10 times. For cases
+        // where we see non-index-intercepting objects, this gives 10 iterations worth of
+        // opportunity for us to observe that the get_by_val may be polymorphic.
+        if (++byValInfo->slowPathCount >= 10
+            || object->structure(vm)->typeInfo().interceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero()) {
+            // Don't ever try to optimize.
+            ctiPatchCallByReturnAddress(ReturnAddressPtr(OUR_RETURN_ADDRESS), FunctionPtr(operationHasIndexedPropertyGeneric));
         }
     }
+
+    uint32_t index = subscript.asUInt32();
+    if (object->canGetIndexQuickly(index))
+        return JSValue::encode(JSValue(JSValue::JSTrue));
+
+    if (!canAccessArgumentIndexQuickly(*object, index)) {
+        // FIXME: This will make us think that in-bounds typed array accesses are actually
+        // out-of-bounds.
+        // https://bugs.webkit.org/show_bug.cgi?id=149886
+        byValInfo->arrayProfile->setOutOfBounds();
+    }
+    return JSValue::encode(jsBoolean(object->hasPropertyGeneric(exec, index, PropertySlot::InternalMethodType::GetOwnProperty)));
+}
     
-    JSValue result = getByVal(exec, baseValue, subscript, ReturnAddressPtr(OUR_RETURN_ADDRESS));
-    return JSValue::encode(result);
+EncodedJSValue JIT_OPERATION operationHasIndexedPropertyGeneric(ExecState* exec, EncodedJSValue encodedBase, EncodedJSValue encodedSubscript, ByValInfo* byValInfo)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+    JSValue baseValue = JSValue::decode(encodedBase);
+    JSValue subscript = JSValue::decode(encodedSubscript);
+    
+    ASSERT(baseValue.isObject());
+    ASSERT(subscript.isUInt32());
+
+    JSObject* object = asObject(baseValue);
+    uint32_t index = subscript.asUInt32();
+    if (object->canGetIndexQuickly(index))
+        return JSValue::encode(JSValue(JSValue::JSTrue));
+
+    if (!canAccessArgumentIndexQuickly(*object, index)) {
+        // FIXME: This will make us think that in-bounds typed array accesses are actually
+        // out-of-bounds.
+        // https://bugs.webkit.org/show_bug.cgi?id=149886
+        byValInfo->arrayProfile->setOutOfBounds();
+    }
+    return JSValue::encode(jsBoolean(object->hasPropertyGeneric(exec, subscript.asUInt32(), PropertySlot::InternalMethodType::GetOwnProperty)));
 }
     
-EncodedJSValue JIT_OPERATION operationGetByValString(ExecState* exec, EncodedJSValue encodedBase, EncodedJSValue encodedSubscript)
+EncodedJSValue JIT_OPERATION operationGetByValString(ExecState* exec, EncodedJSValue encodedBase, EncodedJSValue encodedSubscript, ByValInfo* byValInfo)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
+    auto scope = DECLARE_THROW_SCOPE(vm);
     JSValue baseValue = JSValue::decode(encodedBase);
     JSValue subscript = JSValue::decode(encodedSubscript);
     
@@ -1456,61 +1890,71 @@ EncodedJSValue JIT_OPERATION operationGetByValString(ExecState* exec, EncodedJSV
             result = asString(baseValue)->getIndex(exec, i);
         else {
             result = baseValue.get(exec, i);
-            if (!isJSString(baseValue))
-                ctiPatchCallByReturnAddress(exec->codeBlock(), ReturnAddressPtr(OUR_RETURN_ADDRESS), FunctionPtr(operationGetByValDefault));
+            if (!isJSString(baseValue)) {
+                ASSERT(exec->bytecodeOffset());
+                ctiPatchCallByReturnAddress(ReturnAddressPtr(OUR_RETURN_ADDRESS), FunctionPtr(byValInfo->stubRoutine ? operationGetByValGeneric : operationGetByValOptimize));
+            }
         }
-    } else if (isName(subscript))
-        result = baseValue.get(exec, jsCast<NameInstance*>(subscript.asCell())->privateName());
-    else {
-        Identifier property(exec, subscript.toString(exec)->value(exec));
+    } else {
+        baseValue.requireObjectCoercible(exec);
+        RETURN_IF_EXCEPTION(scope, encodedJSValue());
+        auto property = subscript.toPropertyKey(exec);
+        RETURN_IF_EXCEPTION(scope, encodedJSValue());
         result = baseValue.get(exec, property);
     }
 
     return JSValue::encode(result);
 }
-    
-void JIT_OPERATION operationTearOffActivation(ExecState* exec, JSCell* activationCell)
-{
-    VM& vm = exec->vm();
-    NativeCallFrameTracer tracer(&vm, exec);
-
-    ASSERT(exec->codeBlock()->needsFullScopeChain());
-    jsCast<JSActivation*>(activationCell)->tearOff(vm);
-}
 
-void JIT_OPERATION operationTearOffArguments(ExecState* exec, JSCell* argumentsCell, JSCell* activationCell)
+EncodedJSValue JIT_OPERATION operationDeleteByIdJSResult(ExecState* exec, EncodedJSValue base, UniquedStringImpl* uid)
 {
-    ASSERT(exec->codeBlock()->usesArguments());
-    if (activationCell) {
-        jsCast<Arguments*>(argumentsCell)->didTearOffActivation(exec, jsCast<JSActivation*>(activationCell));
-        return;
-    }
-    jsCast<Arguments*>(argumentsCell)->tearOff(exec);
+    return JSValue::encode(jsBoolean(operationDeleteById(exec, base, uid)));
 }
 
-EncodedJSValue JIT_OPERATION operationDeleteById(ExecState* exec, EncodedJSValue encodedBase, const Identifier* identifier)
+size_t JIT_OPERATION operationDeleteById(ExecState* exec, EncodedJSValue encodedBase, UniquedStringImpl* uid)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
+    auto scope = DECLARE_THROW_SCOPE(vm);
 
     JSObject* baseObj = JSValue::decode(encodedBase).toObject(exec);
-    bool couldDelete = baseObj->methodTable()->deleteProperty(baseObj, exec, *identifier);
-    JSValue result = jsBoolean(couldDelete);
+    if (!baseObj)
+        return false;
+    bool couldDelete = baseObj->methodTable(vm)->deleteProperty(baseObj, exec, Identifier::fromUid(&vm, uid));
     if (!couldDelete && exec->codeBlock()->isStrictMode())
-        vm.throwException(exec, createTypeError(exec, "Unable to delete property."));
-    return JSValue::encode(result);
+        throwTypeError(exec, scope, ASCIILiteral(UnableToDeletePropertyError));
+    return couldDelete;
+}
+
+EncodedJSValue JIT_OPERATION operationDeleteByValJSResult(ExecState* exec, EncodedJSValue base,  EncodedJSValue key)
+{
+    return JSValue::encode(jsBoolean(operationDeleteByVal(exec, base, key)));
 }
 
-JSCell* JIT_OPERATION operationGetPNames(ExecState* exec, JSObject* obj)
+size_t JIT_OPERATION operationDeleteByVal(ExecState* exec, EncodedJSValue encodedBase, EncodedJSValue encodedKey)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
+    auto scope = DECLARE_THROW_SCOPE(vm);
 
-    Structure* structure = obj->structure();
-    JSPropertyNameIterator* jsPropertyNameIterator = structure->enumerationCache();
-    if (!jsPropertyNameIterator || jsPropertyNameIterator->cachedPrototypeChain() != structure->prototypeChain(exec))
-        jsPropertyNameIterator = JSPropertyNameIterator::create(exec, obj);
-    return jsPropertyNameIterator;
+    JSObject* baseObj = JSValue::decode(encodedBase).toObject(exec);
+    JSValue key = JSValue::decode(encodedKey);
+    if (!baseObj)
+        return false;
+
+    bool couldDelete;
+    uint32_t index;
+    if (key.getUInt32(index))
+        couldDelete = baseObj->methodTable(vm)->deletePropertyByIndex(baseObj, exec, index);
+    else {
+        RETURN_IF_EXCEPTION(scope, false);
+        Identifier property = key.toPropertyKey(exec);
+        RETURN_IF_EXCEPTION(scope, false);
+        couldDelete = baseObj->methodTable(vm)->deleteProperty(baseObj, exec, property);
+    }
+    if (!couldDelete && exec->codeBlock()->isStrictMode())
+        throwTypeError(exec, scope, ASCIILiteral(UnableToDeletePropertyError));
+    return couldDelete;
 }
 
 EncodedJSValue JIT_OPERATION operationInstanceOf(ExecState* exec, EncodedJSValue encodedValue, EncodedJSValue encodedProto)
@@ -1520,29 +1964,39 @@ EncodedJSValue JIT_OPERATION operationInstanceOf(ExecState* exec, EncodedJSValue
     JSValue value = JSValue::decode(encodedValue);
     JSValue proto = JSValue::decode(encodedProto);
     
-    ASSERT(!value.isObject() || !proto.isObject());
-
     bool result = JSObject::defaultHasInstance(exec, value, proto);
     return JSValue::encode(jsBoolean(result));
 }
 
-CallFrame* JIT_OPERATION operationSizeAndAllocFrameForVarargs(ExecState* exec, EncodedJSValue encodedArguments, int32_t firstFreeRegister)
+int32_t JIT_OPERATION operationSizeFrameForForwardArguments(ExecState* exec, EncodedJSValue, int32_t numUsedStackSlots, int32_t)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+    return sizeFrameForForwardArguments(exec, vm, numUsedStackSlots);
+}
+
+int32_t JIT_OPERATION operationSizeFrameForVarargs(ExecState* exec, EncodedJSValue encodedArguments, int32_t numUsedStackSlots, int32_t firstVarArgOffset)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
-    JSStack* stack = &exec->interpreter()->stack();
     JSValue arguments = JSValue::decode(encodedArguments);
-    CallFrame* newCallFrame = sizeAndAllocFrameForVarargs(exec, stack, arguments, firstFreeRegister);
+    return sizeFrameForVarargs(exec, vm, arguments, numUsedStackSlots, firstVarArgOffset);
+}
+
+CallFrame* JIT_OPERATION operationSetupForwardArgumentsFrame(ExecState* exec, CallFrame* newCallFrame, EncodedJSValue, int32_t, int32_t length)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+    setupForwardArgumentsFrame(exec, newCallFrame, length);
     return newCallFrame;
 }
 
-CallFrame* JIT_OPERATION operationLoadVarargs(ExecState* exec, CallFrame* newCallFrame, EncodedJSValue encodedThis, EncodedJSValue encodedArguments)
+CallFrame* JIT_OPERATION operationSetupVarargsFrame(ExecState* exec, CallFrame* newCallFrame, EncodedJSValue encodedArguments, int32_t firstVarArgOffset, int32_t length)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
-    JSValue thisValue = JSValue::decode(encodedThis);
     JSValue arguments = JSValue::decode(encodedArguments);
-    loadVarargs(exec, newCallFrame, thisValue, arguments);
+    setupVarargsFrame(exec, newCallFrame, arguments, firstVarArgOffset, length);
     return newCallFrame;
 }
 
@@ -1550,7 +2004,10 @@ EncodedJSValue JIT_OPERATION operationToObject(ExecState* exec, EncodedJSValue v
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
-    return JSValue::encode(JSValue::decode(value).toObject(exec));
+    JSObject* obj = JSValue::decode(value).toObject(exec);
+    if (!obj)
+        return JSValue::encode(JSValue());
+    return JSValue::encode(obj);
 }
 
 char* JIT_OPERATION operationSwitchCharWithUnknownKeyType(ExecState* exec, EncodedJSValue encodedKey, size_t tableIndex)
@@ -1609,141 +2066,652 @@ char* JIT_OPERATION operationSwitchStringWithUnknownKeyType(ExecState* exec, Enc
     return reinterpret_cast<char*>(result);
 }
 
-EncodedJSValue JIT_OPERATION operationResolveScope(ExecState* exec, int32_t identifierIndex)
-{
-    VM& vm = exec->vm();
-    NativeCallFrameTracer tracer(&vm, exec);
-    const Identifier& ident = exec->codeBlock()->identifier(identifierIndex);
-    return JSValue::encode(JSScope::resolve(exec, exec->scope(), ident));
-}
-
 EncodedJSValue JIT_OPERATION operationGetFromScope(ExecState* exec, Instruction* bytecodePC)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
+    auto throwScope = DECLARE_THROW_SCOPE(vm);
+
     CodeBlock* codeBlock = exec->codeBlock();
     Instruction* pc = bytecodePC;
 
     const Identifier& ident = codeBlock->identifier(pc[3].u.operand);
     JSObject* scope = jsCast<JSObject*>(exec->uncheckedR(pc[2].u.operand).jsValue());
-    ResolveModeAndType modeAndType(pc[4].u.operand);
+    GetPutInfo getPutInfo(pc[4].u.operand);
 
-    PropertySlot slot(scope);
-    if (!scope->getPropertySlot(exec, ident, slot)) {
-        if (modeAndType.mode() == ThrowIfNotFound)
-            vm.throwException(exec, createUndefinedVariableError(exec, ident));
-        return JSValue::encode(jsUndefined());
-    }
+    // ModuleVar is always converted to ClosureVar for get_from_scope.
+    ASSERT(getPutInfo.resolveType() != ModuleVar);
 
-    // Covers implicit globals. Since they don't exist until they first execute, we didn't know how to cache them at compile time.
-    if (slot.isCacheableValue() && slot.slotBase() == scope && scope->structure()->propertyAccessesAreCacheable()) {
-        if (modeAndType.type() == GlobalProperty || modeAndType.type() == GlobalPropertyWithVarInjectionChecks) {
-            ConcurrentJITLocker locker(codeBlock->m_lock);
-            pc[5].u.structure.set(exec->vm(), codeBlock->ownerExecutable(), scope->structure());
-            pc[6].u.operand = slot.cachedOffset();
+    return JSValue::encode(scope->getPropertySlot(exec, ident, [&] (bool found, PropertySlot& slot) -> JSValue {
+        if (!found) {
+            if (getPutInfo.resolveMode() == ThrowIfNotFound)
+                throwException(exec, throwScope, createUndefinedVariableError(exec, ident));
+            return jsUndefined();
         }
-    }
 
-    return JSValue::encode(slot.getValue(exec, ident));
+        JSValue result = JSValue();
+        if (scope->isGlobalLexicalEnvironment()) {
+            // When we can't statically prove we need a TDZ check, we must perform the check on the slow path.
+            result = slot.getValue(exec, ident);
+            if (result == jsTDZValue()) {
+                throwException(exec, throwScope, createTDZError(exec));
+                return jsUndefined();
+            }
+        }
+
+        CommonSlowPaths::tryCacheGetFromScopeGlobal(exec, vm, pc, scope, slot, ident);
+
+        if (!result)
+            return slot.getValue(exec, ident);
+        return result;
+    }));
 }
 
 void JIT_OPERATION operationPutToScope(ExecState* exec, Instruction* bytecodePC)
 {
     VM& vm = exec->vm();
     NativeCallFrameTracer tracer(&vm, exec);
+    auto throwScope = DECLARE_THROW_SCOPE(vm);
+
     Instruction* pc = bytecodePC;
 
     CodeBlock* codeBlock = exec->codeBlock();
     const Identifier& ident = codeBlock->identifier(pc[2].u.operand);
     JSObject* scope = jsCast<JSObject*>(exec->uncheckedR(pc[1].u.operand).jsValue());
     JSValue value = exec->r(pc[3].u.operand).jsValue();
-    ResolveModeAndType modeAndType = ResolveModeAndType(pc[4].u.operand);
+    GetPutInfo getPutInfo = GetPutInfo(pc[4].u.operand);
 
-    if (modeAndType.mode() == ThrowIfNotFound && !scope->hasProperty(exec, ident)) {
-        exec->vm().throwException(exec, createUndefinedVariableError(exec, ident));
+    // ModuleVar does not keep the scope register value alive in DFG.
+    ASSERT(getPutInfo.resolveType() != ModuleVar);
+
+    if (getPutInfo.resolveType() == LocalClosureVar) {
+        JSLexicalEnvironment* environment = jsCast<JSLexicalEnvironment*>(scope);
+        environment->variableAt(ScopeOffset(pc[6].u.operand)).set(vm, environment, value);
+        if (WatchpointSet* set = pc[5].u.watchpointSet)
+            set->touch(vm, "Executed op_put_scope<LocalClosureVar>");
         return;
     }
 
-    PutPropertySlot slot(scope, codeBlock->isStrictMode());
+    bool hasProperty = scope->hasProperty(exec, ident);
+    if (hasProperty
+        && scope->isGlobalLexicalEnvironment()
+        && !isInitialization(getPutInfo.initializationMode())) {
+        // When we can't statically prove we need a TDZ check, we must perform the check on the slow path.
+        PropertySlot slot(scope, PropertySlot::InternalMethodType::Get);
+        JSGlobalLexicalEnvironment::getOwnPropertySlot(scope, exec, ident, slot);
+        if (slot.getValue(exec, ident) == jsTDZValue()) {
+            throwException(exec, throwScope, createTDZError(exec));
+            return;
+        }
+    }
+
+    if (getPutInfo.resolveMode() == ThrowIfNotFound && !hasProperty) {
+        throwException(exec, throwScope, createUndefinedVariableError(exec, ident));
+        return;
+    }
+
+    PutPropertySlot slot(scope, codeBlock->isStrictMode(), PutPropertySlot::UnknownContext, isInitialization(getPutInfo.initializationMode()));
     scope->methodTable()->put(scope, exec, ident, value, slot);
     
-    if (exec->vm().exception())
-        return;
+    RETURN_IF_EXCEPTION(throwScope, void());
 
-    // Covers implicit globals. Since they don't exist until they first execute, we didn't know how to cache them at compile time.
-    if (modeAndType.type() == GlobalProperty || modeAndType.type() == GlobalPropertyWithVarInjectionChecks) {
-        if (slot.isCacheable() && slot.base() == scope && scope->structure()->propertyAccessesAreCacheable()) {
-            ConcurrentJITLocker locker(codeBlock->m_lock);
-            pc[5].u.structure.set(exec->vm(), codeBlock->ownerExecutable(), scope->structure());
-            pc[6].u.operand = slot.cachedOffset();
-        }
-    }
+    CommonSlowPaths::tryCachePutToScopeGlobal(exec, codeBlock, pc, scope, getPutInfo, slot, ident);
 }
 
 void JIT_OPERATION operationThrow(ExecState* exec, EncodedJSValue encodedExceptionValue)
 {
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
+    auto scope = DECLARE_THROW_SCOPE(*vm);
 
     JSValue exceptionValue = JSValue::decode(encodedExceptionValue);
-    vm->throwException(exec, exceptionValue);
+    throwException(exec, scope, exceptionValue);
+
+    // Results stored out-of-band in vm.targetMachinePCForThrow & vm.callFrameForCatch
+    genericUnwind(vm, exec);
+}
+
+char* JIT_OPERATION operationReallocateButterflyToHavePropertyStorageWithInitialCapacity(ExecState* exec, JSObject* object)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+
+    ASSERT(!object->structure()->outOfLineCapacity());
+    Butterfly* result = object->allocateMoreOutOfLineStorage(vm, 0, initialOutOfLineCapacity);
+    object->nukeStructureAndSetButterfly(vm, object->structureID(), result);
+    return reinterpret_cast<char*>(result);
+}
 
-    // Results stored out-of-band in vm.targetMachinePCForThrow & vm.callFrameForThrow
-    genericUnwind(vm, exec, exceptionValue);
+char* JIT_OPERATION operationReallocateButterflyToGrowPropertyStorage(ExecState* exec, JSObject* object, size_t newSize)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+
+    Butterfly* result = object->allocateMoreOutOfLineStorage(vm, object->structure()->outOfLineCapacity(), newSize);
+    object->nukeStructureAndSetButterfly(vm, object->structureID(), result);
+    return reinterpret_cast<char*>(result);
 }
 
-void JIT_OPERATION operationFlushWriteBarrierBuffer(ExecState* exec, JSCell* cell)
+void JIT_OPERATION operationOSRWriteBarrier(ExecState* exec, JSCell* cell)
 {
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
-    vm->heap.flushWriteBarrierBuffer(cell);
+    vm->heap.writeBarrier(cell);
 }
 
-void JIT_OPERATION operationOSRWriteBarrier(ExecState* exec, JSCell* cell)
+void JIT_OPERATION operationWriteBarrierSlowPath(ExecState* exec, JSCell* cell)
 {
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
-    exec->heap()->writeBarrier(cell);
+    vm->heap.writeBarrierSlowPath(cell);
 }
 
-// NB: We don't include the value as part of the barrier because the write barrier elision
-// phase in the DFG only tracks whether the object being stored to has been barriered. It 
-// would be much more complicated to try to model the value being stored as well.
-void JIT_OPERATION operationUnconditionalWriteBarrier(ExecState* exec, JSCell* cell)
+void JIT_OPERATION lookupExceptionHandler(VM* vm, ExecState* exec)
+{
+    NativeCallFrameTracer tracer(vm, exec);
+    genericUnwind(vm, exec);
+    ASSERT(vm->targetMachinePCForThrow);
+}
+
+void JIT_OPERATION lookupExceptionHandlerFromCallerFrame(VM* vm, ExecState* exec)
+{
+    vm->topCallFrame = exec->callerFrame();
+    genericUnwind(vm, exec, UnwindFromCallerFrame);
+    ASSERT(vm->targetMachinePCForThrow);
+}
+
+void JIT_OPERATION operationVMHandleException(ExecState* exec)
 {
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
-    Heap::writeBarrier(cell);
+    genericUnwind(vm, exec);
 }
 
-void JIT_OPERATION operationInitGlobalConst(ExecState* exec, Instruction* pc)
+// This function "should" just take the ExecState*, but doing so would make it more difficult
+// to call from exception check sites. So, unlike all of our other functions, we allow
+// ourselves to play some gnarly ABI tricks just to simplify the calling convention. This is
+// particularly safe here since this is never called on the critical path - it's only for
+// testing.
+void JIT_OPERATION operationExceptionFuzz(ExecState* exec)
 {
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
+    auto scope = DECLARE_THROW_SCOPE(*vm);
+    UNUSED_PARAM(scope);
+#if COMPILER(GCC_OR_CLANG)
+    void* returnPC = __builtin_return_address(0);
+    doExceptionFuzzing(exec, scope, "JITOperations", returnPC);
+#endif // COMPILER(GCC_OR_CLANG)
+}
+
+EncodedJSValue JIT_OPERATION operationHasGenericProperty(ExecState* exec, EncodedJSValue encodedBaseValue, JSCell* propertyName)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+    JSValue baseValue = JSValue::decode(encodedBaseValue);
+    if (baseValue.isUndefinedOrNull())
+        return JSValue::encode(jsBoolean(false));
+
+    JSObject* base = baseValue.toObject(exec);
+    if (!base)
+        return JSValue::encode(JSValue());
+    return JSValue::encode(jsBoolean(base->hasPropertyGeneric(exec, asString(propertyName)->toIdentifier(exec), PropertySlot::InternalMethodType::GetOwnProperty)));
+}
+
+EncodedJSValue JIT_OPERATION operationHasIndexedProperty(ExecState* exec, JSCell* baseCell, int32_t subscript, int32_t internalMethodType)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+    JSObject* object = baseCell->toObject(exec, exec->lexicalGlobalObject());
+    return JSValue::encode(jsBoolean(object->hasPropertyGeneric(exec, subscript, static_cast<PropertySlot::InternalMethodType>(internalMethodType))));
+}
+    
+JSCell* JIT_OPERATION operationGetPropertyEnumerator(ExecState* exec, JSCell* cell)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+
+    JSObject* base = cell->toObject(exec, exec->lexicalGlobalObject());
+
+    return propertyNameEnumerator(exec, base);
+}
+
+EncodedJSValue JIT_OPERATION operationNextEnumeratorPname(ExecState* exec, JSCell* enumeratorCell, int32_t index)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+    JSPropertyNameEnumerator* enumerator = jsCast<JSPropertyNameEnumerator*>(enumeratorCell);
+    JSString* propertyName = enumerator->propertyNameAtIndex(index);
+    return JSValue::encode(propertyName ? propertyName : jsNull());
+}
 
-    JSValue value = exec->r(pc[2].u.operand).jsValue();
-    pc[1].u.registerPointer->set(*vm, exec->codeBlock()->globalObject(), value);
+JSCell* JIT_OPERATION operationToIndexString(ExecState* exec, int32_t index)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+    return jsString(exec, Identifier::from(exec, index).string());
 }
 
-void JIT_OPERATION lookupExceptionHandler(ExecState* exec)
+ALWAYS_INLINE static EncodedJSValue unprofiledAdd(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2)
 {
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
+    
+    JSValue op1 = JSValue::decode(encodedOp1);
+    JSValue op2 = JSValue::decode(encodedOp2);
+    
+    return JSValue::encode(jsAdd(exec, op1, op2));
+}
 
-    JSValue exceptionValue = exec->exception();
-    ASSERT(exceptionValue);
+ALWAYS_INLINE static EncodedJSValue profiledAdd(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, ArithProfile& arithProfile)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
     
-    genericUnwind(vm, exec, exceptionValue);
-    ASSERT(vm->targetMachinePCForThrow);
+    JSValue op1 = JSValue::decode(encodedOp1);
+    JSValue op2 = JSValue::decode(encodedOp2);
+
+    arithProfile.observeLHSAndRHS(op1, op2);
+    JSValue result = jsAdd(exec, op1, op2);
+    arithProfile.observeResult(result);
+
+    return JSValue::encode(result);
 }
 
-void JIT_OPERATION operationVMHandleException(ExecState* exec)
+EncodedJSValue JIT_OPERATION operationValueAdd(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2)
+{
+    return unprofiledAdd(exec, encodedOp1, encodedOp2);
+}
+
+EncodedJSValue JIT_OPERATION operationValueAddProfiled(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, ArithProfile* arithProfile)
+{
+    ASSERT(arithProfile);
+    return profiledAdd(exec, encodedOp1, encodedOp2, *arithProfile);
+}
+
+EncodedJSValue JIT_OPERATION operationValueAddProfiledOptimize(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, JITAddIC* addIC)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+    
+    JSValue op1 = JSValue::decode(encodedOp1);
+    JSValue op2 = JSValue::decode(encodedOp2);
+
+    ArithProfile* arithProfile = addIC->arithProfile();
+    ASSERT(arithProfile);
+    arithProfile->observeLHSAndRHS(op1, op2);
+    auto nonOptimizeVariant = operationValueAddProfiledNoOptimize;
+    addIC->generateOutOfLine(*vm, exec->codeBlock(), nonOptimizeVariant);
+
+#if ENABLE(MATH_IC_STATS)
+    exec->codeBlock()->dumpMathICStats();
+#endif
+    
+    JSValue result = jsAdd(exec, op1, op2);
+    arithProfile->observeResult(result);
+
+    return JSValue::encode(result);
+}
+
+EncodedJSValue JIT_OPERATION operationValueAddProfiledNoOptimize(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, JITAddIC* addIC)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    ArithProfile* arithProfile = addIC->arithProfile();
+    ASSERT(arithProfile);
+    return profiledAdd(exec, encodedOp1, encodedOp2, *arithProfile);
+}
+
+EncodedJSValue JIT_OPERATION operationValueAddOptimize(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, JITAddIC* addIC)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    JSValue op1 = JSValue::decode(encodedOp1);
+    JSValue op2 = JSValue::decode(encodedOp2);
+
+    auto nonOptimizeVariant = operationValueAddNoOptimize;
+    if (ArithProfile* arithProfile = addIC->arithProfile())
+        arithProfile->observeLHSAndRHS(op1, op2);
+    addIC->generateOutOfLine(*vm, exec->codeBlock(), nonOptimizeVariant);
+
+#if ENABLE(MATH_IC_STATS)
+    exec->codeBlock()->dumpMathICStats();
+#endif
+
+    return JSValue::encode(jsAdd(exec, op1, op2));
+}
+
+EncodedJSValue JIT_OPERATION operationValueAddNoOptimize(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, JITAddIC*)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+    
+    JSValue op1 = JSValue::decode(encodedOp1);
+    JSValue op2 = JSValue::decode(encodedOp2);
+    
+    JSValue result = jsAdd(exec, op1, op2);
+
+    return JSValue::encode(result);
+}
+
+ALWAYS_INLINE static EncodedJSValue unprofiledMul(VM& vm, ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2)
+{
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    JSValue op1 = JSValue::decode(encodedOp1);
+    JSValue op2 = JSValue::decode(encodedOp2);
+
+    double a = op1.toNumber(exec);
+    RETURN_IF_EXCEPTION(scope, encodedJSValue());
+    double b = op2.toNumber(exec);
+    return JSValue::encode(jsNumber(a * b));
+}
+
+ALWAYS_INLINE static EncodedJSValue profiledMul(VM& vm, ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, ArithProfile& arithProfile, bool shouldObserveLHSAndRHSTypes = true)
+{
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    JSValue op1 = JSValue::decode(encodedOp1);
+    JSValue op2 = JSValue::decode(encodedOp2);
+
+    if (shouldObserveLHSAndRHSTypes)
+        arithProfile.observeLHSAndRHS(op1, op2);
+
+    double a = op1.toNumber(exec);
+    RETURN_IF_EXCEPTION(scope, encodedJSValue());
+    double b = op2.toNumber(exec);
+    RETURN_IF_EXCEPTION(scope, encodedJSValue());
+    
+    JSValue result = jsNumber(a * b);
+    arithProfile.observeResult(result);
+    return JSValue::encode(result);
+}
+
+EncodedJSValue JIT_OPERATION operationValueMul(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    return unprofiledMul(*vm, exec, encodedOp1, encodedOp2);
+}
+
+EncodedJSValue JIT_OPERATION operationValueMulNoOptimize(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, JITMulIC*)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    return unprofiledMul(*vm, exec, encodedOp1, encodedOp2);
+}
+
+EncodedJSValue JIT_OPERATION operationValueMulOptimize(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, JITMulIC* mulIC)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    auto nonOptimizeVariant = operationValueMulNoOptimize;
+    if (ArithProfile* arithProfile = mulIC->arithProfile())
+        arithProfile->observeLHSAndRHS(JSValue::decode(encodedOp1), JSValue::decode(encodedOp2));
+    mulIC->generateOutOfLine(*vm, exec->codeBlock(), nonOptimizeVariant);
+
+#if ENABLE(MATH_IC_STATS)
+    exec->codeBlock()->dumpMathICStats();
+#endif
+
+    return unprofiledMul(*vm, exec, encodedOp1, encodedOp2);
+}
+
+EncodedJSValue JIT_OPERATION operationValueMulProfiled(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, ArithProfile* arithProfile)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    ASSERT(arithProfile);
+    return profiledMul(*vm, exec, encodedOp1, encodedOp2, *arithProfile);
+}
+
+EncodedJSValue JIT_OPERATION operationValueMulProfiledOptimize(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, JITMulIC* mulIC)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    ArithProfile* arithProfile = mulIC->arithProfile();
+    ASSERT(arithProfile);
+    arithProfile->observeLHSAndRHS(JSValue::decode(encodedOp1), JSValue::decode(encodedOp2));
+    auto nonOptimizeVariant = operationValueMulProfiledNoOptimize;
+    mulIC->generateOutOfLine(*vm, exec->codeBlock(), nonOptimizeVariant);
+
+#if ENABLE(MATH_IC_STATS)
+    exec->codeBlock()->dumpMathICStats();
+#endif
+
+    return profiledMul(*vm, exec, encodedOp1, encodedOp2, *arithProfile, false);
+}
+
+EncodedJSValue JIT_OPERATION operationValueMulProfiledNoOptimize(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, JITMulIC* mulIC)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    ArithProfile* arithProfile = mulIC->arithProfile();
+    ASSERT(arithProfile);
+    return profiledMul(*vm, exec, encodedOp1, encodedOp2, *arithProfile);
+}
+
+ALWAYS_INLINE static EncodedJSValue unprofiledNegate(ExecState* exec, EncodedJSValue encodedOperand)
+{
+    VM& vm = exec->vm();
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    NativeCallFrameTracer tracer(&vm, exec);
+    
+    JSValue operand = JSValue::decode(encodedOperand);
+    double number = operand.toNumber(exec);
+    if (UNLIKELY(scope.exception()))
+        return JSValue::encode(JSValue());
+    return JSValue::encode(jsNumber(-number));
+}
+
+ALWAYS_INLINE static EncodedJSValue profiledNegate(ExecState* exec, EncodedJSValue encodedOperand, ArithProfile& arithProfile)
+{
+    VM& vm = exec->vm();
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    NativeCallFrameTracer tracer(&vm, exec);
+
+    JSValue operand = JSValue::decode(encodedOperand);
+    arithProfile.observeLHS(operand);
+    double number = operand.toNumber(exec);
+    if (UNLIKELY(scope.exception()))
+        return JSValue::encode(JSValue());
+
+    JSValue result = jsNumber(-number);
+    arithProfile.observeResult(result);
+    return JSValue::encode(result);
+}
+
+EncodedJSValue JIT_OPERATION operationArithNegate(ExecState* exec, EncodedJSValue operand)
+{
+    return unprofiledNegate(exec, operand);
+}
+
+EncodedJSValue JIT_OPERATION operationArithNegateProfiled(ExecState* exec, EncodedJSValue operand, ArithProfile* arithProfile)
 {
+    ASSERT(arithProfile);
+    return profiledNegate(exec, operand, *arithProfile);
+}
+
+EncodedJSValue JIT_OPERATION operationArithNegateProfiledOptimize(ExecState* exec, EncodedJSValue encodedOperand, JITNegIC* negIC)
+{
+    VM& vm = exec->vm();
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    NativeCallFrameTracer tracer(&vm, exec);
+    
+    JSValue operand = JSValue::decode(encodedOperand);
+
+    ArithProfile* arithProfile = negIC->arithProfile();
+    ASSERT(arithProfile);
+    arithProfile->observeLHS(operand);
+    negIC->generateOutOfLine(vm, exec->codeBlock(), operationArithNegateProfiled);
+
+#if ENABLE(MATH_IC_STATS)
+    exec->codeBlock()->dumpMathICStats();
+#endif
+    
+    double number = operand.toNumber(exec);
+    if (UNLIKELY(scope.exception()))
+        return JSValue::encode(JSValue());
+    JSValue result = jsNumber(-number);
+    arithProfile->observeResult(result);
+    return JSValue::encode(result);
+}
+
+EncodedJSValue JIT_OPERATION operationArithNegateOptimize(ExecState* exec, EncodedJSValue encodedOperand, JITNegIC* negIC)
+{
+    VM& vm = exec->vm();
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    NativeCallFrameTracer tracer(&vm, exec);
+
+    JSValue operand = JSValue::decode(encodedOperand);
+
+    if (ArithProfile* arithProfile = negIC->arithProfile())
+        arithProfile->observeLHS(operand);
+    negIC->generateOutOfLine(vm, exec->codeBlock(), operationArithNegate);
+
+#if ENABLE(MATH_IC_STATS)
+    exec->codeBlock()->dumpMathICStats();
+#endif
+
+    double number = operand.toNumber(exec);
+    if (UNLIKELY(scope.exception()))
+        return JSValue::encode(JSValue());
+    return JSValue::encode(jsNumber(-number));
+}
+
+ALWAYS_INLINE static EncodedJSValue unprofiledSub(VM& vm, ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2)
+{
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    JSValue op1 = JSValue::decode(encodedOp1);
+    JSValue op2 = JSValue::decode(encodedOp2);
+
+    double a = op1.toNumber(exec);
+    RETURN_IF_EXCEPTION(scope, encodedJSValue());
+    double b = op2.toNumber(exec);
+    return JSValue::encode(jsNumber(a - b));
+}
+
+ALWAYS_INLINE static EncodedJSValue profiledSub(VM& vm, ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, ArithProfile& arithProfile, bool shouldObserveLHSAndRHSTypes = true)
+{
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    JSValue op1 = JSValue::decode(encodedOp1);
+    JSValue op2 = JSValue::decode(encodedOp2);
+
+    if (shouldObserveLHSAndRHSTypes)
+        arithProfile.observeLHSAndRHS(op1, op2);
+
+    double a = op1.toNumber(exec);
+    RETURN_IF_EXCEPTION(scope, encodedJSValue());
+    double b = op2.toNumber(exec);
+    RETURN_IF_EXCEPTION(scope, encodedJSValue());
+    
+    JSValue result = jsNumber(a - b);
+    arithProfile.observeResult(result);
+    return JSValue::encode(result);
+}
+
+EncodedJSValue JIT_OPERATION operationValueSub(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+    return unprofiledSub(*vm, exec, encodedOp1, encodedOp2);
+}
+
+EncodedJSValue JIT_OPERATION operationValueSubProfiled(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, ArithProfile* arithProfile)
+{
+    ASSERT(arithProfile);
+
     VM* vm = &exec->vm();
     NativeCallFrameTracer tracer(vm, exec);
 
-    ASSERT(!exec->isVMEntrySentinel());
-    genericUnwind(vm, exec, vm->exception());
+    return profiledSub(*vm, exec, encodedOp1, encodedOp2, *arithProfile);
+}
+
+EncodedJSValue JIT_OPERATION operationValueSubOptimize(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, JITSubIC* subIC)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    auto nonOptimizeVariant = operationValueSubNoOptimize;
+    if (ArithProfile* arithProfile = subIC->arithProfile())
+        arithProfile->observeLHSAndRHS(JSValue::decode(encodedOp1), JSValue::decode(encodedOp2));
+    subIC->generateOutOfLine(*vm, exec->codeBlock(), nonOptimizeVariant);
+
+#if ENABLE(MATH_IC_STATS)
+    exec->codeBlock()->dumpMathICStats();
+#endif
+
+    return unprofiledSub(*vm, exec, encodedOp1, encodedOp2);
+}
+
+EncodedJSValue JIT_OPERATION operationValueSubNoOptimize(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, JITSubIC*)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    return unprofiledSub(*vm, exec, encodedOp1, encodedOp2);
+}
+
+EncodedJSValue JIT_OPERATION operationValueSubProfiledOptimize(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, JITSubIC* subIC)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    ArithProfile* arithProfile = subIC->arithProfile();
+    ASSERT(arithProfile);
+    arithProfile->observeLHSAndRHS(JSValue::decode(encodedOp1), JSValue::decode(encodedOp2));
+    auto nonOptimizeVariant = operationValueSubProfiledNoOptimize;
+    subIC->generateOutOfLine(*vm, exec->codeBlock(), nonOptimizeVariant);
+
+#if ENABLE(MATH_IC_STATS)
+    exec->codeBlock()->dumpMathICStats();
+#endif
+
+    return profiledSub(*vm, exec, encodedOp1, encodedOp2, *arithProfile, false);
+}
+
+EncodedJSValue JIT_OPERATION operationValueSubProfiledNoOptimize(ExecState* exec, EncodedJSValue encodedOp1, EncodedJSValue encodedOp2, JITSubIC* subIC)
+{
+    VM* vm = &exec->vm();
+    NativeCallFrameTracer tracer(vm, exec);
+
+    ArithProfile* arithProfile = subIC->arithProfile();
+    ASSERT(arithProfile);
+    return profiledSub(*vm, exec, encodedOp1, encodedOp2, *arithProfile);
+}
+
+void JIT_OPERATION operationProcessTypeProfilerLog(ExecState* exec)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+    vm.typeProfilerLog()->processLogEntries(ASCIILiteral("Log Full, called from inside baseline JIT"));
+}
+
+void JIT_OPERATION operationProcessShadowChickenLog(ExecState* exec)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+    vm.shadowChicken().update(vm, exec);
+}
+
+int32_t JIT_OPERATION operationCheckIfExceptionIsUncatchableAndNotifyProfiler(ExecState* exec)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    RELEASE_ASSERT(!!scope.exception());
+
+    if (isTerminatedExecutionException(vm, scope.exception())) {
+        genericUnwind(&vm, exec);
+        return 1;
+    }
+    return 0;
 }
 
 } // extern "C"
@@ -1758,28 +2726,32 @@ extern "C" EncodedJSValue HOST_CALL_RETURN_VALUE_OPTION getHostCallReturnValueWi
     return JSValue::encode(exec->vm().hostCallReturnValue);
 }
 
-#if COMPILER(GCC) && CPU(X86_64)
+#if COMPILER(GCC_OR_CLANG) && CPU(X86_64)
 asm (
 ".globl " SYMBOL_STRING(getHostCallReturnValue) "\n"
 HIDE_SYMBOL(getHostCallReturnValue) "\n"
 SYMBOL_STRING(getHostCallReturnValue) ":" "\n"
-    "mov 0(%rbp), %rbp\n" // CallerFrameAndPC::callerFrame
-    "mov %rbp, %rdi\n"
+    "lea -8(%rsp), %rdi\n"
     "jmp " LOCAL_REFERENCE(getHostCallReturnValueWithExecState) "\n"
 );
 
-#elif COMPILER(GCC) && CPU(X86)
+#elif COMPILER(GCC_OR_CLANG) && CPU(X86)
 asm (
 ".text" "\n" \
 ".globl " SYMBOL_STRING(getHostCallReturnValue) "\n"
 HIDE_SYMBOL(getHostCallReturnValue) "\n"
 SYMBOL_STRING(getHostCallReturnValue) ":" "\n"
-    "mov 0(%ebp), %ebp\n" // CallerFrameAndPC::callerFrame
-    "mov %ebp, 4(%esp)\n"
-    "jmp " LOCAL_REFERENCE(getHostCallReturnValueWithExecState) "\n"
+    "push %ebp\n"
+    "mov %esp, %eax\n"
+    "leal -4(%esp), %esp\n"
+    "push %eax\n"
+    "call " LOCAL_REFERENCE(getHostCallReturnValueWithExecState) "\n"
+    "leal 8(%esp), %esp\n"
+    "pop %ebp\n"
+    "ret\n"
 );
 
-#elif COMPILER(GCC) && CPU(ARM_THUMB2)
+#elif COMPILER(GCC_OR_CLANG) && CPU(ARM_THUMB2)
 asm (
 ".text" "\n"
 ".align 2" "\n"
@@ -1788,20 +2760,18 @@ HIDE_SYMBOL(getHostCallReturnValue) "\n"
 ".thumb" "\n"
 ".thumb_func " THUMB_FUNC_PARAM(getHostCallReturnValue) "\n"
 SYMBOL_STRING(getHostCallReturnValue) ":" "\n"
-    "ldr r7, [r7, #0]" "\n" // CallerFrameAndPC::callerFrame
-    "mov r0, r7" "\n"
+    "sub r0, sp, #8" "\n"
     "b " LOCAL_REFERENCE(getHostCallReturnValueWithExecState) "\n"
 );
 
-#elif COMPILER(GCC) && CPU(ARM_TRADITIONAL)
+#elif COMPILER(GCC_OR_CLANG) && CPU(ARM_TRADITIONAL)
 asm (
 ".text" "\n"
 ".globl " SYMBOL_STRING(getHostCallReturnValue) "\n"
 HIDE_SYMBOL(getHostCallReturnValue) "\n"
 INLINE_ARM_FUNCTION(getHostCallReturnValue)
 SYMBOL_STRING(getHostCallReturnValue) ":" "\n"
-    "ldr r11, [r11, #0]" "\n" // CallerFrameAndPC::callerFrame
-    "mov r0, r11" "\n"
+    "sub r0, sp, #8" "\n"
     "b " LOCAL_REFERENCE(getHostCallReturnValueWithExecState) "\n"
 );
 
@@ -1812,44 +2782,38 @@ asm (
 ".globl " SYMBOL_STRING(getHostCallReturnValue) "\n"
 HIDE_SYMBOL(getHostCallReturnValue) "\n"
 SYMBOL_STRING(getHostCallReturnValue) ":" "\n"
-    "ldur x29, [x29, #0]" "\n"
-     "mov x0, x29" "\n"
+     "sub x0, sp, #16" "\n"
      "b " LOCAL_REFERENCE(getHostCallReturnValueWithExecState) "\n"
 );
 
-#elif COMPILER(GCC) && CPU(MIPS)
+#elif COMPILER(GCC_OR_CLANG) && CPU(MIPS)
+
+#if WTF_MIPS_PIC
+#define LOAD_FUNCTION_TO_T9(function) \
+        ".set noreorder" "\n" \
+        ".cpload $25" "\n" \
+        ".set reorder" "\n" \
+        "la $t9, " LOCAL_REFERENCE(function) "\n"
+#else
+#define LOAD_FUNCTION_TO_T9(function) "" "\n"
+#endif
+
 asm (
 ".text" "\n"
 ".globl " SYMBOL_STRING(getHostCallReturnValue) "\n"
 HIDE_SYMBOL(getHostCallReturnValue) "\n"
 SYMBOL_STRING(getHostCallReturnValue) ":" "\n"
     LOAD_FUNCTION_TO_T9(getHostCallReturnValueWithExecState)
-    "lw $fp, 0($fp)" "\n" // CallerFrameAndPC::callerFrame
-    "move $a0, $fp" "\n"
+    "addi $a0, $sp, -8" "\n"
     "b " LOCAL_REFERENCE(getHostCallReturnValueWithExecState) "\n"
 );
 
-#elif COMPILER(GCC) && CPU(SH4)
-asm (
-".text" "\n"
-".globl " SYMBOL_STRING(getHostCallReturnValue) "\n"
-HIDE_SYMBOL(getHostCallReturnValue) "\n"
-SYMBOL_STRING(getHostCallReturnValue) ":" "\n"
-    "mov.l @r14, r14" "\n" // CallerFrameAndPC::callerFrame
-    "mov r14, r4" "\n"
-    "mov.l 2f, " SH4_SCRATCH_REGISTER "\n"
-    "braf " SH4_SCRATCH_REGISTER "\n"
-    "nop" "\n"
-    "1: .balign 4" "\n"
-    "2: .long " LOCAL_REFERENCE(getHostCallReturnValueWithExecState) "-1b\n"
-);
-
 #elif COMPILER(MSVC) && CPU(X86)
 extern "C" {
     __declspec(naked) EncodedJSValue HOST_CALL_RETURN_VALUE_OPTION getHostCallReturnValue()
     {
-        __asm mov ebp, [ebp + 0]; // CallerFrameAndPC::callerFrame
-        __asm mov [esp + 4], ebp;
+        __asm lea eax, [esp - 4]
+        __asm mov [esp + 4], eax;
         __asm jmp getHostCallReturnValueWithExecState
     }
 }