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diff --git a/Source/JavaScriptCore/jit/ScratchRegisterAllocator.cpp b/Source/JavaScriptCore/jit/ScratchRegisterAllocator.cpp
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+++ b/Source/JavaScriptCore/jit/ScratchRegisterAllocator.cpp
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+/*
+ * Copyright (C) 2014, 2015 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#include "config.h"
+#include "ScratchRegisterAllocator.h"
+
+#if ENABLE(JIT)
+
+#include "JSCInlines.h"
+#include "MaxFrameExtentForSlowPathCall.h"
+#include "VM.h"
+
+namespace JSC {
+
+ScratchRegisterAllocator::ScratchRegisterAllocator(const RegisterSet& usedRegisters)
+    : m_usedRegisters(usedRegisters)
+    , m_numberOfReusedRegisters(0)
+{
+}
+
+ScratchRegisterAllocator::~ScratchRegisterAllocator() { }
+
+void ScratchRegisterAllocator::lock(GPRReg reg)
+{
+    if (reg == InvalidGPRReg)
+        return;
+    unsigned index = GPRInfo::toIndex(reg);
+    if (index == GPRInfo::InvalidIndex)
+        return;
+    m_lockedRegisters.setGPRByIndex(index);
+}
+
+void ScratchRegisterAllocator::lock(FPRReg reg)
+{
+    if (reg == InvalidFPRReg)
+        return;
+    unsigned index = FPRInfo::toIndex(reg);
+    if (index == FPRInfo::InvalidIndex)
+        return;
+    m_lockedRegisters.setFPRByIndex(index);
+}
+
+void ScratchRegisterAllocator::lock(JSValueRegs regs)
+{
+    lock(regs.tagGPR());
+    lock(regs.payloadGPR());
+}
+
+template<typename BankInfo>
+typename BankInfo::RegisterType ScratchRegisterAllocator::allocateScratch()
+{
+    // First try to allocate a register that is totally free.
+    for (unsigned i = 0; i < BankInfo::numberOfRegisters; ++i) {
+        typename BankInfo::RegisterType reg = BankInfo::toRegister(i);
+        if (!m_lockedRegisters.get(reg)
+            && !m_usedRegisters.get(reg)
+            && !m_scratchRegisters.get(reg)) {
+            m_scratchRegisters.set(reg);
+            return reg;
+        }
+    }
+    
+    // Since that failed, try to allocate a register that is not yet
+    // locked or used for scratch.
+    for (unsigned i = 0; i < BankInfo::numberOfRegisters; ++i) {
+        typename BankInfo::RegisterType reg = BankInfo::toRegister(i);
+        if (!m_lockedRegisters.get(reg) && !m_scratchRegisters.get(reg)) {
+            m_scratchRegisters.set(reg);
+            m_numberOfReusedRegisters++;
+            return reg;
+        }
+    }
+        
+    // We failed.
+    CRASH();
+    // Make some silly compilers happy.
+    return static_cast<typename BankInfo::RegisterType>(-1);
+}
+
+GPRReg ScratchRegisterAllocator::allocateScratchGPR() { return allocateScratch<GPRInfo>(); }
+FPRReg ScratchRegisterAllocator::allocateScratchFPR() { return allocateScratch<FPRInfo>(); }
+
+ScratchRegisterAllocator::PreservedState ScratchRegisterAllocator::preserveReusedRegistersByPushing(MacroAssembler& jit, ExtraStackSpace extraStackSpace)
+{
+    if (!didReuseRegisters())
+        return PreservedState(0, extraStackSpace);
+
+    RegisterSet registersToSpill;
+    for (unsigned i = 0; i < FPRInfo::numberOfRegisters; ++i) {
+        FPRReg reg = FPRInfo::toRegister(i);
+        if (m_scratchRegisters.getFPRByIndex(i) && m_usedRegisters.get(reg))
+            registersToSpill.set(reg);
+    }
+    for (unsigned i = 0; i < GPRInfo::numberOfRegisters; ++i) {
+        GPRReg reg = GPRInfo::toRegister(i);
+        if (m_scratchRegisters.getGPRByIndex(i) && m_usedRegisters.get(reg))
+            registersToSpill.set(reg);
+    }
+
+    unsigned extraStackBytesAtTopOfStack = extraStackSpace == ExtraStackSpace::SpaceForCCall ? maxFrameExtentForSlowPathCall : 0;
+    unsigned stackAdjustmentSize = ScratchRegisterAllocator::preserveRegistersToStackForCall(jit, registersToSpill, extraStackBytesAtTopOfStack);
+
+    return PreservedState(stackAdjustmentSize, extraStackSpace);
+}
+
+void ScratchRegisterAllocator::restoreReusedRegistersByPopping(MacroAssembler& jit, const ScratchRegisterAllocator::PreservedState& preservedState)
+{
+    RELEASE_ASSERT(preservedState);
+    if (!didReuseRegisters())
+        return;
+
+    RegisterSet registersToFill;
+    for (unsigned i = GPRInfo::numberOfRegisters; i--;) {
+        GPRReg reg = GPRInfo::toRegister(i);
+        if (m_scratchRegisters.getGPRByIndex(i) && m_usedRegisters.get(reg))
+            registersToFill.set(reg);
+    }
+    for (unsigned i = FPRInfo::numberOfRegisters; i--;) {
+        FPRReg reg = FPRInfo::toRegister(i);
+        if (m_scratchRegisters.getFPRByIndex(i) && m_usedRegisters.get(reg))
+            registersToFill.set(reg);
+    }
+
+    unsigned extraStackBytesAtTopOfStack =
+        preservedState.extraStackSpaceRequirement == ExtraStackSpace::SpaceForCCall ? maxFrameExtentForSlowPathCall : 0;
+    RegisterSet dontRestore; // Empty set. We want to restore everything.
+    ScratchRegisterAllocator::restoreRegistersFromStackForCall(jit, registersToFill, dontRestore,
+        preservedState.numberOfBytesPreserved, extraStackBytesAtTopOfStack);
+}
+
+RegisterSet ScratchRegisterAllocator::usedRegistersForCall() const
+{
+    RegisterSet result = m_usedRegisters;
+    result.exclude(RegisterSet::registersToNotSaveForJSCall());
+    return result;
+}
+
+unsigned ScratchRegisterAllocator::desiredScratchBufferSizeForCall() const
+{
+    return usedRegistersForCall().numberOfSetRegisters() * sizeof(JSValue);
+}
+
+void ScratchRegisterAllocator::preserveUsedRegistersToScratchBufferForCall(MacroAssembler& jit, ScratchBuffer* scratchBuffer, GPRReg scratchGPR)
+{
+    RegisterSet usedRegisters = usedRegistersForCall();
+    if (!usedRegisters.numberOfSetRegisters())
+        return;
+    
+    unsigned count = 0;
+    for (GPRReg reg = MacroAssembler::firstRegister(); reg <= MacroAssembler::lastRegister(); reg = MacroAssembler::nextRegister(reg)) {
+        if (usedRegisters.get(reg)) {
+            jit.storePtr(reg, static_cast<EncodedJSValue*>(scratchBuffer->dataBuffer()) + count);
+            count++;
+        }
+        if (GPRInfo::toIndex(reg) != GPRInfo::InvalidIndex
+            && scratchGPR == InvalidGPRReg
+            && !m_lockedRegisters.get(reg) && !m_scratchRegisters.get(reg))
+            scratchGPR = reg;
+    }
+    RELEASE_ASSERT(scratchGPR != InvalidGPRReg);
+    for (FPRReg reg = MacroAssembler::firstFPRegister(); reg <= MacroAssembler::lastFPRegister(); reg = MacroAssembler::nextFPRegister(reg)) {
+        if (usedRegisters.get(reg)) {
+            jit.move(MacroAssembler::TrustedImmPtr(static_cast<EncodedJSValue*>(scratchBuffer->dataBuffer()) + count), scratchGPR);
+            count++;
+            jit.storeDouble(reg, scratchGPR);
+        }
+    }
+    RELEASE_ASSERT(count * sizeof(JSValue) == desiredScratchBufferSizeForCall());
+    
+    jit.move(MacroAssembler::TrustedImmPtr(scratchBuffer->activeLengthPtr()), scratchGPR);
+    jit.storePtr(MacroAssembler::TrustedImmPtr(static_cast<size_t>(count * sizeof(JSValue))), scratchGPR);
+}
+
+void ScratchRegisterAllocator::restoreUsedRegistersFromScratchBufferForCall(MacroAssembler& jit, ScratchBuffer* scratchBuffer, GPRReg scratchGPR)
+{
+    RegisterSet usedRegisters = usedRegistersForCall();
+    if (!usedRegisters.numberOfSetRegisters())
+        return;
+    
+    if (scratchGPR == InvalidGPRReg) {
+        // Find a scratch register.
+        for (unsigned i = GPRInfo::numberOfRegisters; i--;) {
+            if (m_lockedRegisters.getGPRByIndex(i) || m_scratchRegisters.getGPRByIndex(i))
+                continue;
+            scratchGPR = GPRInfo::toRegister(i);
+            break;
+        }
+    }
+    RELEASE_ASSERT(scratchGPR != InvalidGPRReg);
+    
+    jit.move(MacroAssembler::TrustedImmPtr(scratchBuffer->activeLengthPtr()), scratchGPR);
+    jit.storePtr(MacroAssembler::TrustedImmPtr(0), scratchGPR);
+
+    // Restore double registers first.
+    unsigned count = usedRegisters.numberOfSetGPRs();
+    for (FPRReg reg = MacroAssembler::firstFPRegister(); reg <= MacroAssembler::lastFPRegister(); reg = MacroAssembler::nextFPRegister(reg)) {
+        if (usedRegisters.get(reg)) {
+            jit.move(MacroAssembler::TrustedImmPtr(static_cast<EncodedJSValue*>(scratchBuffer->dataBuffer()) + (count++)), scratchGPR);
+            jit.loadDouble(scratchGPR, reg);
+        }
+    }
+        
+    count = 0;
+    for (GPRReg reg = MacroAssembler::firstRegister(); reg <= MacroAssembler::lastRegister(); reg = MacroAssembler::nextRegister(reg)) {
+        if (usedRegisters.get(reg))
+            jit.loadPtr(static_cast<EncodedJSValue*>(scratchBuffer->dataBuffer()) + (count++), reg);
+    }
+}
+
+unsigned ScratchRegisterAllocator::preserveRegistersToStackForCall(MacroAssembler& jit, const RegisterSet& usedRegisters, unsigned extraBytesAtTopOfStack)
+{
+    RELEASE_ASSERT(extraBytesAtTopOfStack % sizeof(void*) == 0);
+    if (!usedRegisters.numberOfSetRegisters())
+        return 0;
+    
+    unsigned stackOffset = (usedRegisters.numberOfSetRegisters()) * sizeof(EncodedJSValue);
+    stackOffset += extraBytesAtTopOfStack;
+    stackOffset = WTF::roundUpToMultipleOf(stackAlignmentBytes(), stackOffset);
+    jit.subPtr(
+        MacroAssembler::TrustedImm32(stackOffset),
+        MacroAssembler::stackPointerRegister);
+
+    unsigned count = 0;
+    for (GPRReg reg = MacroAssembler::firstRegister(); reg <= MacroAssembler::lastRegister(); reg = MacroAssembler::nextRegister(reg)) {
+        if (usedRegisters.get(reg)) {
+            jit.storePtr(reg, MacroAssembler::Address(MacroAssembler::stackPointerRegister, extraBytesAtTopOfStack + (count * sizeof(EncodedJSValue))));
+            count++;
+        }
+    }
+    for (FPRReg reg = MacroAssembler::firstFPRegister(); reg <= MacroAssembler::lastFPRegister(); reg = MacroAssembler::nextFPRegister(reg)) {
+        if (usedRegisters.get(reg)) {
+            jit.storeDouble(reg, MacroAssembler::Address(MacroAssembler::stackPointerRegister, extraBytesAtTopOfStack + (count * sizeof(EncodedJSValue))));
+            count++;
+        }
+    }
+
+    RELEASE_ASSERT(count == usedRegisters.numberOfSetRegisters());
+
+    return stackOffset;
+}
+
+void ScratchRegisterAllocator::restoreRegistersFromStackForCall(MacroAssembler& jit, const RegisterSet& usedRegisters, const RegisterSet& ignore, unsigned numberOfStackBytesUsedForRegisterPreservation, unsigned extraBytesAtTopOfStack)
+{
+    RELEASE_ASSERT(extraBytesAtTopOfStack % sizeof(void*) == 0);
+    if (!usedRegisters.numberOfSetRegisters()) {
+        RELEASE_ASSERT(numberOfStackBytesUsedForRegisterPreservation == 0);
+        return;
+    }
+
+    unsigned count = 0;
+    for (GPRReg reg = MacroAssembler::firstRegister(); reg <= MacroAssembler::lastRegister(); reg = MacroAssembler::nextRegister(reg)) {
+        if (usedRegisters.get(reg)) {
+            if (!ignore.get(reg))
+                jit.loadPtr(MacroAssembler::Address(MacroAssembler::stackPointerRegister, extraBytesAtTopOfStack + (sizeof(EncodedJSValue) * count)), reg);
+            count++;
+        }
+    }
+    for (FPRReg reg = MacroAssembler::firstFPRegister(); reg <= MacroAssembler::lastFPRegister(); reg = MacroAssembler::nextFPRegister(reg)) {
+        if (usedRegisters.get(reg)) {
+            if (!ignore.get(reg))
+                jit.loadDouble(MacroAssembler::Address(MacroAssembler::stackPointerRegister, extraBytesAtTopOfStack + (sizeof(EncodedJSValue) * count)), reg);
+            count++;
+        }
+    }
+
+    unsigned stackOffset = (usedRegisters.numberOfSetRegisters()) * sizeof(EncodedJSValue);
+    stackOffset += extraBytesAtTopOfStack;
+    stackOffset = WTF::roundUpToMultipleOf(stackAlignmentBytes(), stackOffset);
+
+    RELEASE_ASSERT(count == usedRegisters.numberOfSetRegisters());
+    RELEASE_ASSERT(stackOffset == numberOfStackBytesUsedForRegisterPreservation);
+
+    jit.addPtr(
+        MacroAssembler::TrustedImm32(stackOffset),
+        MacroAssembler::stackPointerRegister);
+}
+
+} // namespace JSC
+
+#endif // ENABLE(JIT)