webkitgtk-2.4.11webkitgtk-2.4.11

1 files changed, 89 insertions, 463 deletions

diff --git a/Source/JavaScriptCore/ftl/FTLOSRExitCompiler.cpp b/Source/JavaScriptCore/ftl/FTLOSRExitCompiler.cpp
index 473192211..076a495ea 100644
--- a/Source/JavaScriptCore/ftl/FTLOSRExitCompiler.cpp
+++ b/Source/JavaScriptCore/ftl/FTLOSRExitCompiler.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013-2015 Apple Inc. All rights reserved.
+ * Copyright (C) 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -32,513 +32,155 @@
 #include "DFGOSRExitPreparation.h"
 #include "FTLExitArgumentForOperand.h"
 #include "FTLJITCode.h"
-#include "FTLLocation.h"
 #include "FTLOSRExit.h"
-#include "FTLOperations.h"
-#include "FTLState.h"
 #include "FTLSaveRestore.h"
-#include "LinkBuffer.h"
-#include "MaxFrameExtentForSlowPathCall.h"
 #include "OperandsInlines.h"
-#include "JSCInlines.h"
+#include "Operations.h"
+#include "RepatchBuffer.h"
 
 namespace JSC { namespace FTL {
 
 using namespace DFG;
 
-static void reboxAccordingToFormat(
-    DataFormat format, AssemblyHelpers& jit, GPRReg value, GPRReg scratch1, GPRReg scratch2)
-{
-    switch (format) {
-    case DataFormatInt32: {
-        jit.zeroExtend32ToPtr(value, value);
-        jit.or64(GPRInfo::tagTypeNumberRegister, value);
-        break;
-    }
-
-    case DataFormatInt52: {
-        jit.rshift64(AssemblyHelpers::TrustedImm32(JSValue::int52ShiftAmount), value);
-        jit.moveDoubleTo64(FPRInfo::fpRegT0, scratch2);
-        jit.boxInt52(value, value, scratch1, FPRInfo::fpRegT0);
-        jit.move64ToDouble(scratch2, FPRInfo::fpRegT0);
-        break;
-    }
-
-    case DataFormatStrictInt52: {
-        jit.moveDoubleTo64(FPRInfo::fpRegT0, scratch2);
-        jit.boxInt52(value, value, scratch1, FPRInfo::fpRegT0);
-        jit.move64ToDouble(scratch2, FPRInfo::fpRegT0);
-        break;
-    }
-
-    case DataFormatBoolean: {
-        jit.zeroExtend32ToPtr(value, value);
-        jit.or32(MacroAssembler::TrustedImm32(ValueFalse), value);
-        break;
-    }
-
-    case DataFormatJS: {
-        // Done already!
-        break;
-    }
-
-    case DataFormatDouble: {
-        jit.moveDoubleTo64(FPRInfo::fpRegT0, scratch1);
-        jit.move64ToDouble(value, FPRInfo::fpRegT0);
-        jit.purifyNaN(FPRInfo::fpRegT0);
-        jit.boxDouble(FPRInfo::fpRegT0, value);
-        jit.move64ToDouble(scratch1, FPRInfo::fpRegT0);
-        break;
-    }
-
-    default:
-        RELEASE_ASSERT_NOT_REACHED();
-        break;
-    }
-}
-
-static void compileRecovery(
-    CCallHelpers& jit, const ExitValue& value,
-    Vector<B3::ValueRep>& valueReps,
-    char* registerScratch,
-    const HashMap<ExitTimeObjectMaterialization*, EncodedJSValue*>& materializationToPointer)
-{
-    switch (value.kind()) {
-    case ExitValueDead:
-        jit.move(MacroAssembler::TrustedImm64(JSValue::encode(jsUndefined())), GPRInfo::regT0);
-        break;
-            
-    case ExitValueConstant:
-        jit.move(MacroAssembler::TrustedImm64(JSValue::encode(value.constant())), GPRInfo::regT0);
-        break;
-            
-    case ExitValueArgument:
-        Location::forValueRep(valueReps[value.exitArgument().argument()]).restoreInto(
-            jit, registerScratch, GPRInfo::regT0);
-        break;
-            
-    case ExitValueInJSStack:
-    case ExitValueInJSStackAsInt32:
-    case ExitValueInJSStackAsInt52:
-    case ExitValueInJSStackAsDouble:
-        jit.load64(AssemblyHelpers::addressFor(value.virtualRegister()), GPRInfo::regT0);
-        break;
-            
-    case ExitValueRecovery:
-        Location::forValueRep(valueReps[value.rightRecoveryArgument()]).restoreInto(
-            jit, registerScratch, GPRInfo::regT1);
-        Location::forValueRep(valueReps[value.leftRecoveryArgument()]).restoreInto(
-            jit, registerScratch, GPRInfo::regT0);
-        switch (value.recoveryOpcode()) {
-        case AddRecovery:
-            switch (value.recoveryFormat()) {
-            case DataFormatInt32:
-                jit.add32(GPRInfo::regT1, GPRInfo::regT0);
-                break;
-            case DataFormatInt52:
-                jit.add64(GPRInfo::regT1, GPRInfo::regT0);
-                break;
-            default:
-                RELEASE_ASSERT_NOT_REACHED();
-                break;
-            }
-            break;
-        case SubRecovery:
-            switch (value.recoveryFormat()) {
-            case DataFormatInt32:
-                jit.sub32(GPRInfo::regT1, GPRInfo::regT0);
-                break;
-            case DataFormatInt52:
-                jit.sub64(GPRInfo::regT1, GPRInfo::regT0);
-                break;
-            default:
-                RELEASE_ASSERT_NOT_REACHED();
-                break;
-            }
-            break;
-        default:
-            RELEASE_ASSERT_NOT_REACHED();
-            break;
-        }
-        break;
-        
-    case ExitValueMaterializeNewObject:
-        jit.loadPtr(materializationToPointer.get(value.objectMaterialization()), GPRInfo::regT0);
-        break;
-            
-    default:
-        RELEASE_ASSERT_NOT_REACHED();
-        break;
-    }
-        
-    reboxAccordingToFormat(
-        value.dataFormat(), jit, GPRInfo::regT0, GPRInfo::regT1, GPRInfo::regT2);
-}
-
 static void compileStub(
     unsigned exitID, JITCode* jitCode, OSRExit& exit, VM* vm, CodeBlock* codeBlock)
 {
+    StackMaps::Record* record;
+    
+    for (unsigned i = jitCode->stackmaps.records.size(); i--;) {
+        record = &jitCode->stackmaps.records[i];
+        if (record->patchpointID == exit.m_stackmapID)
+            break;
+    }
+    
+    RELEASE_ASSERT(record->patchpointID == exit.m_stackmapID);
+    
     // This code requires framePointerRegister is the same as callFrameRegister
     static_assert(MacroAssembler::framePointerRegister == GPRInfo::callFrameRegister, "MacroAssembler::framePointerRegister and GPRInfo::callFrameRegister must be the same");
 
     CCallHelpers jit(vm, codeBlock);
-
-    // The first thing we need to do is restablish our frame in the case of an exception.
-    if (exit.isGenericUnwindHandler()) {
-        RELEASE_ASSERT(vm->callFrameForCatch); // The first time we hit this exit, like at all other times, this field should be non-null.
-        jit.restoreCalleeSavesFromVMCalleeSavesBuffer();
-        jit.loadPtr(vm->addressOfCallFrameForCatch(), MacroAssembler::framePointerRegister);
-        jit.addPtr(CCallHelpers::TrustedImm32(codeBlock->stackPointerOffset() * sizeof(Register)),
-            MacroAssembler::framePointerRegister, CCallHelpers::stackPointerRegister);
-
-        // Do a pushToSave because that's what the exit compiler below expects the stack
-        // to look like because that's the last thing the ExitThunkGenerator does. The code
-        // below doesn't actually use the value that was pushed, but it does rely on the
-        // general shape of the stack being as it is in the non-exception OSR case.
-        jit.pushToSaveImmediateWithoutTouchingRegisters(CCallHelpers::TrustedImm32(0xbadbeef));
-    }
-
-    // We need scratch space to save all registers, to build up the JS stack, to deal with unwind
-    // fixup, pointers to all of the objects we materialize, and the elements inside those objects
-    // that we materialize.
-    
-    // Figure out how much space we need for those object allocations.
-    unsigned numMaterializations = 0;
-    size_t maxMaterializationNumArguments = 0;
-    for (ExitTimeObjectMaterialization* materialization : exit.m_descriptor->m_materializations) {
-        numMaterializations++;
-        
-        maxMaterializationNumArguments = std::max(
-            maxMaterializationNumArguments,
-            materialization->properties().size());
-    }
     
-    ScratchBuffer* scratchBuffer = vm->scratchBufferForSize(
-        sizeof(EncodedJSValue) * (
-            exit.m_descriptor->m_values.size() + numMaterializations + maxMaterializationNumArguments) +
-        requiredScratchMemorySizeInBytes() +
-        codeBlock->calleeSaveRegisters()->size() * sizeof(uint64_t));
+    // We need scratch space to save all registers and to build up the JSStack.
+    // Use a scratch buffer to transfer all values.
+    ScratchBuffer* scratchBuffer = vm->scratchBufferForSize(sizeof(EncodedJSValue) * exit.m_values.size() + requiredScratchMemorySizeInBytes());
     EncodedJSValue* scratch = scratchBuffer ? static_cast<EncodedJSValue*>(scratchBuffer->dataBuffer()) : 0;
-    EncodedJSValue* materializationPointers = scratch + exit.m_descriptor->m_values.size();
-    EncodedJSValue* materializationArguments = materializationPointers + numMaterializations;
-    char* registerScratch = bitwise_cast<char*>(materializationArguments + maxMaterializationNumArguments);
-    uint64_t* unwindScratch = bitwise_cast<uint64_t*>(registerScratch + requiredScratchMemorySizeInBytes());
-    
-    HashMap<ExitTimeObjectMaterialization*, EncodedJSValue*> materializationToPointer;
-    unsigned materializationCount = 0;
-    for (ExitTimeObjectMaterialization* materialization : exit.m_descriptor->m_materializations) {
-        materializationToPointer.add(
-            materialization, materializationPointers + materializationCount++);
-    }
-
-    auto recoverValue = [&] (const ExitValue& value) {
-        compileRecovery(
-            jit, value,
-            exit.m_valueReps,
-            registerScratch, materializationToPointer);
-    };
+    char* registerScratch = bitwise_cast<char*>(scratch + exit.m_values.size());
     
-    // Note that we come in here, the stack used to be as B3 left it except that someone called pushToSave().
-    // We don't care about the value they saved. But, we do appreciate the fact that they did it, because we use
-    // that slot for saveAllRegisters().
-
+    // Make sure that saveAllRegisters() has a place on top of the stack to spill things. That
+    // function expects to be able to use top of stack for scratch memory.
+    jit.push(GPRInfo::regT0);
     saveAllRegisters(jit, registerScratch);
     
-    // Bring the stack back into a sane form and assert that it's sane.
-    jit.popToRestore(GPRInfo::regT0);
-    jit.checkStackPointerAlignment();
+    // Bring the stack back into a sane form.
+    jit.pop(GPRInfo::regT0);
+    jit.pop(GPRInfo::regT0);
     
-    if (vm->m_perBytecodeProfiler && jitCode->dfgCommon()->compilation) {
-        Profiler::Database& database = *vm->m_perBytecodeProfiler;
-        Profiler::Compilation* compilation = jitCode->dfgCommon()->compilation.get();
-        
-        Profiler::OSRExit* profilerExit = compilation->addOSRExit(
-            exitID, Profiler::OriginStack(database, codeBlock, exit.m_codeOrigin),
-            exit.m_kind, exit.m_kind == UncountableInvalidation);
-        jit.add64(CCallHelpers::TrustedImm32(1), CCallHelpers::AbsoluteAddress(profilerExit->counterAddress()));
-    }
-
     // The remaining code assumes that SP/FP are in the same state that they were in the FTL's
     // call frame.
     
     // Get the call frame and tag thingies.
     // Restore the exiting function's callFrame value into a regT4
+    record->locations[0].restoreInto(jit, jitCode->stackmaps, registerScratch, GPRInfo::regT4);
     jit.move(MacroAssembler::TrustedImm64(TagTypeNumber), GPRInfo::tagTypeNumberRegister);
     jit.move(MacroAssembler::TrustedImm64(TagMask), GPRInfo::tagMaskRegister);
     
     // Do some value profiling.
-    if (exit.m_descriptor->m_profileDataFormat != DataFormatNone) {
-        Location::forValueRep(exit.m_valueReps[0]).restoreInto(jit, registerScratch, GPRInfo::regT0);
+    if (exit.m_profileValueFormat != InvalidValueFormat) {
+        record->locations[1].restoreInto(jit, jitCode->stackmaps, registerScratch, GPRInfo::regT0);
         reboxAccordingToFormat(
-            exit.m_descriptor->m_profileDataFormat, jit, GPRInfo::regT0, GPRInfo::regT1, GPRInfo::regT2);
+            exit.m_profileValueFormat, jit, GPRInfo::regT0, GPRInfo::regT1, GPRInfo::regT2);
         
         if (exit.m_kind == BadCache || exit.m_kind == BadIndexingType) {
             CodeOrigin codeOrigin = exit.m_codeOriginForExitProfile;
             if (ArrayProfile* arrayProfile = jit.baselineCodeBlockFor(codeOrigin)->getArrayProfile(codeOrigin.bytecodeIndex)) {
-                jit.load32(MacroAssembler::Address(GPRInfo::regT0, JSCell::structureIDOffset()), GPRInfo::regT1);
-                jit.store32(GPRInfo::regT1, arrayProfile->addressOfLastSeenStructureID());
-                jit.load8(MacroAssembler::Address(GPRInfo::regT0, JSCell::indexingTypeOffset()), GPRInfo::regT1);
+                jit.loadPtr(MacroAssembler::Address(GPRInfo::regT0, JSCell::structureOffset()), GPRInfo::regT1);
+                jit.storePtr(GPRInfo::regT1, arrayProfile->addressOfLastSeenStructure());
+                jit.load8(MacroAssembler::Address(GPRInfo::regT1, Structure::indexingTypeOffset()), GPRInfo::regT1);
                 jit.move(MacroAssembler::TrustedImm32(1), GPRInfo::regT2);
                 jit.lshift32(GPRInfo::regT1, GPRInfo::regT2);
                 jit.or32(GPRInfo::regT2, MacroAssembler::AbsoluteAddress(arrayProfile->addressOfArrayModes()));
             }
         }
-
-        if (!!exit.m_descriptor->m_valueProfile)
-            jit.store64(GPRInfo::regT0, exit.m_descriptor->m_valueProfile.getSpecFailBucket(0));
-    }
-
-    // Materialize all objects. Don't materialize an object until all
-    // of the objects it needs have been materialized. We break cycles
-    // by populating objects late - we only consider an object as
-    // needing another object if the later is needed for the
-    // allocation of the former.
-
-    HashSet<ExitTimeObjectMaterialization*> toMaterialize;
-    for (ExitTimeObjectMaterialization* materialization : exit.m_descriptor->m_materializations)
-        toMaterialize.add(materialization);
-
-    while (!toMaterialize.isEmpty()) {
-        unsigned previousToMaterializeSize = toMaterialize.size();
-
-        Vector<ExitTimeObjectMaterialization*> worklist;
-        worklist.appendRange(toMaterialize.begin(), toMaterialize.end());
-        for (ExitTimeObjectMaterialization* materialization : worklist) {
-            // Check if we can do anything about this right now.
-            bool allGood = true;
-            for (ExitPropertyValue value : materialization->properties()) {
-                if (!value.value().isObjectMaterialization())
-                    continue;
-                if (!value.location().neededForMaterialization())
-                    continue;
-                if (toMaterialize.contains(value.value().objectMaterialization())) {
-                    // Gotta skip this one, since it needs a
-                    // materialization that hasn't been materialized.
-                    allGood = false;
-                    break;
-                }
-            }
-            if (!allGood)
-                continue;
-
-            // All systems go for materializing the object. First we
-            // recover the values of all of its fields and then we
-            // call a function to actually allocate the beast.
-            // We only recover the fields that are needed for the allocation.
-            for (unsigned propertyIndex = materialization->properties().size(); propertyIndex--;) {
-                const ExitPropertyValue& property = materialization->properties()[propertyIndex];
-                if (!property.location().neededForMaterialization())
-                    continue;
-
-                recoverValue(property.value());
-                jit.storePtr(GPRInfo::regT0, materializationArguments + propertyIndex);
-            }
-            
-            // This call assumes that we don't pass arguments on the stack.
-            jit.setupArgumentsWithExecState(
-                CCallHelpers::TrustedImmPtr(materialization),
-                CCallHelpers::TrustedImmPtr(materializationArguments));
-            jit.move(CCallHelpers::TrustedImmPtr(bitwise_cast<void*>(operationMaterializeObjectInOSR)), GPRInfo::nonArgGPR0);
-            jit.call(GPRInfo::nonArgGPR0);
-            jit.storePtr(GPRInfo::returnValueGPR, materializationToPointer.get(materialization));
-
-            // Let everyone know that we're done.
-            toMaterialize.remove(materialization);
-        }
         
-        // We expect progress! This ensures that we crash rather than looping infinitely if there
-        // is something broken about this fixpoint. Or, this could happen if we ever violate the
-        // "materializations form a DAG" rule.
-        RELEASE_ASSERT(toMaterialize.size() < previousToMaterializeSize);
-    }
-
-    // Now that all the objects have been allocated, we populate them
-    // with the correct values. This time we can recover all the
-    // fields, including those that are only needed for the allocation.
-    for (ExitTimeObjectMaterialization* materialization : exit.m_descriptor->m_materializations) {
-        for (unsigned propertyIndex = materialization->properties().size(); propertyIndex--;) {
-            recoverValue(materialization->properties()[propertyIndex].value());
-            jit.storePtr(GPRInfo::regT0, materializationArguments + propertyIndex);
-        }
-
-        // This call assumes that we don't pass arguments on the stack
-        jit.setupArgumentsWithExecState(
-            CCallHelpers::TrustedImmPtr(materialization),
-            CCallHelpers::TrustedImmPtr(materializationToPointer.get(materialization)),
-            CCallHelpers::TrustedImmPtr(materializationArguments));
-        jit.move(CCallHelpers::TrustedImmPtr(bitwise_cast<void*>(operationPopulateObjectInOSR)), GPRInfo::nonArgGPR0);
-        jit.call(GPRInfo::nonArgGPR0);
+        if (!!exit.m_valueProfile)
+            jit.store64(GPRInfo::regT0, exit.m_valueProfile.getSpecFailBucket(0));
     }
 
     // Save all state from wherever the exit data tells us it was, into the appropriate place in
-    // the scratch buffer. This also does the reboxing.
+    // the scratch buffer. This doesn't rebox any values yet.
     
-    for (unsigned index = exit.m_descriptor->m_values.size(); index--;) {
-        recoverValue(exit.m_descriptor->m_values[index]);
+    for (unsigned index = exit.m_values.size(); index--;) {
+        ExitValue value = exit.m_values[index];
+        
+        switch (value.kind()) {
+        case ExitValueDead:
+            jit.move(MacroAssembler::TrustedImm64(JSValue::encode(jsUndefined())), GPRInfo::regT0);
+            break;
+            
+        case ExitValueConstant:
+            jit.move(MacroAssembler::TrustedImm64(JSValue::encode(value.constant())), GPRInfo::regT0);
+            break;
+            
+        case ExitValueArgument:
+            record->locations[value.exitArgument().argument()].restoreInto(
+                jit, jitCode->stackmaps, registerScratch, GPRInfo::regT0);
+            break;
+            
+        case ExitValueInJSStack:
+        case ExitValueInJSStackAsInt32:
+        case ExitValueInJSStackAsInt52:
+        case ExitValueInJSStackAsDouble:
+            jit.load64(AssemblyHelpers::addressFor(value.virtualRegister(), GPRInfo::regT4), GPRInfo::regT0);
+            break;
+            
+        default:
+            RELEASE_ASSERT_NOT_REACHED();
+            break;
+        }
+        
         jit.store64(GPRInfo::regT0, scratch + index);
     }
     
-    // Henceforth we make it look like the exiting function was called through a register
-    // preservation wrapper. This implies that FP must be nudged down by a certain amount. Then
-    // we restore the various things according to either exit.m_descriptor->m_values or by copying from the
-    // old frame, and finally we save the various callee-save registers into where the
-    // restoration thunk would restore them from.
-    
-    // Before we start messing with the frame, we need to set aside any registers that the
-    // FTL code was preserving.
-    for (unsigned i = codeBlock->calleeSaveRegisters()->size(); i--;) {
-        RegisterAtOffset entry = codeBlock->calleeSaveRegisters()->at(i);
-        jit.load64(
-            MacroAssembler::Address(MacroAssembler::framePointerRegister, entry.offset()),
-            GPRInfo::regT0);
-        jit.store64(GPRInfo::regT0, unwindScratch + i);
-    }
-    
-    jit.load32(CCallHelpers::payloadFor(JSStack::ArgumentCount), GPRInfo::regT2);
-    
-    // Let's say that the FTL function had failed its arity check. In that case, the stack will
-    // contain some extra stuff.
-    //
-    // We compute the padded stack space:
-    //
-    //     paddedStackSpace = roundUp(codeBlock->numParameters - regT2 + 1)
-    //
-    // The stack will have regT2 + CallFrameHeaderSize stuff.
-    // We want to make the stack look like this, from higher addresses down:
-    //
-    //     - argument padding
-    //     - actual arguments
-    //     - call frame header
-
-    // This code assumes that we're dealing with FunctionCode.
-    RELEASE_ASSERT(codeBlock->codeType() == FunctionCode);
-    
-    jit.add32(
-        MacroAssembler::TrustedImm32(-codeBlock->numParameters()), GPRInfo::regT2,
-        GPRInfo::regT3);
-    MacroAssembler::Jump arityIntact = jit.branch32(
-        MacroAssembler::GreaterThanOrEqual, GPRInfo::regT3, MacroAssembler::TrustedImm32(0));
-    jit.neg32(GPRInfo::regT3);
-    jit.add32(MacroAssembler::TrustedImm32(1 + stackAlignmentRegisters() - 1), GPRInfo::regT3);
-    jit.and32(MacroAssembler::TrustedImm32(-stackAlignmentRegisters()), GPRInfo::regT3);
-    jit.add32(GPRInfo::regT3, GPRInfo::regT2);
-    arityIntact.link(&jit);
-
-    CodeBlock* baselineCodeBlock = jit.baselineCodeBlockFor(exit.m_codeOrigin);
-
-    // First set up SP so that our data doesn't get clobbered by signals.
-    unsigned conservativeStackDelta =
-        (exit.m_descriptor->m_values.numberOfLocals() + baselineCodeBlock->calleeSaveSpaceAsVirtualRegisters()) * sizeof(Register) +
-        maxFrameExtentForSlowPathCall;
-    conservativeStackDelta = WTF::roundUpToMultipleOf(
-        stackAlignmentBytes(), conservativeStackDelta);
-    jit.addPtr(
-        MacroAssembler::TrustedImm32(-conservativeStackDelta),
-        MacroAssembler::framePointerRegister, MacroAssembler::stackPointerRegister);
-    jit.checkStackPointerAlignment();
-
-    RegisterSet allFTLCalleeSaves = RegisterSet::ftlCalleeSaveRegisters();
-    RegisterAtOffsetList* baselineCalleeSaves = baselineCodeBlock->calleeSaveRegisters();
-    RegisterAtOffsetList* vmCalleeSaves = vm->getAllCalleeSaveRegisterOffsets();
-    RegisterSet vmCalleeSavesToSkip = RegisterSet::stackRegisters();
-    if (exit.isExceptionHandler())
-        jit.move(CCallHelpers::TrustedImmPtr(vm->calleeSaveRegistersBuffer), GPRInfo::regT1);
-
-    for (Reg reg = Reg::first(); reg <= Reg::last(); reg = reg.next()) {
-        if (!allFTLCalleeSaves.get(reg)) {
-            if (exit.isExceptionHandler())
-                RELEASE_ASSERT(!vmCalleeSaves->find(reg));
-            continue;
-        }
-        unsigned unwindIndex = codeBlock->calleeSaveRegisters()->indexOf(reg);
-        RegisterAtOffset* baselineRegisterOffset = baselineCalleeSaves->find(reg);
-        RegisterAtOffset* vmCalleeSave = nullptr; 
-        if (exit.isExceptionHandler())
-            vmCalleeSave = vmCalleeSaves->find(reg);
-
-        if (reg.isGPR()) {
-            GPRReg regToLoad = baselineRegisterOffset ? GPRInfo::regT0 : reg.gpr();
-            RELEASE_ASSERT(regToLoad != GPRInfo::regT1);
-
-            if (unwindIndex == UINT_MAX) {
-                // The FTL compilation didn't preserve this register. This means that it also
-                // didn't use the register. So its value at the beginning of OSR exit should be
-                // preserved by the thunk. Luckily, we saved all registers into the register
-                // scratch buffer, so we can restore them from there.
-                jit.load64(registerScratch + offsetOfReg(reg), regToLoad);
-            } else {
-                // The FTL compilation preserved the register. Its new value is therefore
-                // irrelevant, but we can get the value that was preserved by using the unwind
-                // data. We've already copied all unwind-able preserved registers into the unwind
-                // scratch buffer, so we can get it from there.
-                jit.load64(unwindScratch + unwindIndex, regToLoad);
-            }
-
-            if (baselineRegisterOffset)
-                jit.store64(regToLoad, MacroAssembler::Address(MacroAssembler::framePointerRegister, baselineRegisterOffset->offset()));
-            if (vmCalleeSave && !vmCalleeSavesToSkip.get(vmCalleeSave->reg()))
-                jit.store64(regToLoad, MacroAssembler::Address(GPRInfo::regT1, vmCalleeSave->offset()));
-        } else {
-            FPRReg fpRegToLoad = baselineRegisterOffset ? FPRInfo::fpRegT0 : reg.fpr();
-
-            if (unwindIndex == UINT_MAX)
-                jit.loadDouble(MacroAssembler::TrustedImmPtr(registerScratch + offsetOfReg(reg)), fpRegToLoad);
-            else
-                jit.loadDouble(MacroAssembler::TrustedImmPtr(unwindScratch + unwindIndex), fpRegToLoad);
-
-            if (baselineRegisterOffset)
-                jit.storeDouble(fpRegToLoad, MacroAssembler::Address(MacroAssembler::framePointerRegister, baselineRegisterOffset->offset()));
-            if (vmCalleeSave && !vmCalleeSavesToSkip.get(vmCalleeSave->reg()))
-                jit.storeDouble(fpRegToLoad, MacroAssembler::Address(GPRInfo::regT1, vmCalleeSave->offset()));
-        }
-    }
-
-    if (exit.isExceptionHandler()) {
-        RegisterAtOffset* vmCalleeSave = vmCalleeSaves->find(GPRInfo::tagTypeNumberRegister);
-        jit.store64(GPRInfo::tagTypeNumberRegister, MacroAssembler::Address(GPRInfo::regT1, vmCalleeSave->offset()));
-
-        vmCalleeSave = vmCalleeSaves->find(GPRInfo::tagMaskRegister);
-        jit.store64(GPRInfo::tagMaskRegister, MacroAssembler::Address(GPRInfo::regT1, vmCalleeSave->offset()));
-    }
-
-    size_t baselineVirtualRegistersForCalleeSaves = baselineCodeBlock->calleeSaveSpaceAsVirtualRegisters();
-
-    // Now get state out of the scratch buffer and place it back into the stack. The values are
-    // already reboxed so we just move them.
-    for (unsigned index = exit.m_descriptor->m_values.size(); index--;) {
-        VirtualRegister reg = exit.m_descriptor->m_values.virtualRegisterForIndex(index);
-
-        if (reg.isLocal() && reg.toLocal() < static_cast<int>(baselineVirtualRegistersForCalleeSaves))
-            continue;
-
+    // Now get state out of the scratch buffer and place it back into the stack. This part does
+    // all reboxing.
+    for (unsigned index = exit.m_values.size(); index--;) {
+        int operand = exit.m_values.operandForIndex(index);
+        ExitValue value = exit.m_values[index];
+        
         jit.load64(scratch + index, GPRInfo::regT0);
-        jit.store64(GPRInfo::regT0, AssemblyHelpers::addressFor(reg));
+        reboxAccordingToFormat(
+            value.valueFormat(), jit, GPRInfo::regT0, GPRInfo::regT1, GPRInfo::regT2);
+        jit.store64(GPRInfo::regT0, AssemblyHelpers::addressFor(static_cast<VirtualRegister>(operand), GPRInfo::regT4));
     }
     
+    // Restore the old stack pointer and then put regT4 into callFrameRegister. The idea is
+    // that the FTL call frame is pushed onto the JS call frame and we can recover the old
+    // value of the stack pointer by popping the FTL call frame. We already know what the
+    // frame pointer in the JS call frame was because it would have been passed as an argument
+    // to the FTL call frame.
+    jit.move(MacroAssembler::framePointerRegister, MacroAssembler::stackPointerRegister);
+    jit.pop(GPRInfo::nonArgGPR0);
+    jit.pop(GPRInfo::nonArgGPR0);
+    jit.move(GPRInfo::regT4, GPRInfo::callFrameRegister);
+    
     handleExitCounts(jit, exit);
     reifyInlinedCallFrames(jit, exit);
     adjustAndJumpToTarget(jit, exit);
     
-    LinkBuffer patchBuffer(*vm, jit, codeBlock);
+    LinkBuffer patchBuffer(*vm, &jit, codeBlock);
     exit.m_code = FINALIZE_CODE_IF(
-        shouldDumpDisassembly() || Options::verboseOSR() || Options::verboseFTLOSRExit(),
+        shouldShowDisassembly(),
         patchBuffer,
-        ("FTL OSR exit #%u (%s, %s) from %s, with operands = %s",
+        ("FTL OSR exit #%u (%s, %s) from %s, with operands = %s, and record = %s",
             exitID, toCString(exit.m_codeOrigin).data(),
             exitKindToString(exit.m_kind), toCString(*codeBlock).data(),
-            toCString(ignoringContext<DumpContext>(exit.m_descriptor->m_values)).data())
-        );
+            toCString(ignoringContext<DumpContext>(exit.m_values)).data(),
+            toCString(*record).data()));
 }
 
 extern "C" void* compileFTLOSRExit(ExecState* exec, unsigned exitID)
 {
     SamplingRegion samplingRegion("FTL OSR Exit Compilation");
-
-    if (shouldDumpDisassembly() || Options::verboseOSR() || Options::verboseFTLOSRExit())
-        dataLog("Compiling OSR exit with exitID = ", exitID, "\n");
-
-    if (exec->vm().callFrameForCatch)
-        RELEASE_ASSERT(exec->vm().callFrameForCatch == exec);
     
     CodeBlock* codeBlock = exec->codeBlock();
     
@@ -554,28 +196,12 @@ extern "C" void* compileFTLOSRExit(ExecState* exec, unsigned exitID)
     JITCode* jitCode = codeBlock->jitCode()->ftl();
     OSRExit& exit = jitCode->osrExit[exitID];
     
-    if (shouldDumpDisassembly() || Options::verboseOSR() || Options::verboseFTLOSRExit()) {
-        dataLog("    Owning block: ", pointerDump(codeBlock), "\n");
-        dataLog("    Origin: ", exit.m_codeOrigin, "\n");
-        if (exit.m_codeOriginForExitProfile != exit.m_codeOrigin)
-            dataLog("    Origin for exit profile: ", exit.m_codeOriginForExitProfile, "\n");
-        dataLog("    Current call site index: ", exec->callSiteIndex().bits(), "\n");
-        dataLog("    Exit is exception handler: ", exit.isExceptionHandler(), "\n");
-        dataLog("    Is unwind handler: ", exit.isGenericUnwindHandler(), "\n");
-        dataLog("    Exit values: ", exit.m_descriptor->m_values, "\n");
-        dataLog("    Value reps: ", listDump(exit.m_valueReps), "\n");
-        if (!exit.m_descriptor->m_materializations.isEmpty()) {
-            dataLog("    Materializations:\n");
-            for (ExitTimeObjectMaterialization* materialization : exit.m_descriptor->m_materializations)
-                dataLog("        ", pointerDump(materialization), "\n");
-        }
-    }
-
     prepareCodeOriginForOSRExit(exec, exit.m_codeOrigin);
     
     compileStub(exitID, jitCode, exit, vm, codeBlock);
-
-    MacroAssembler::repatchJump(
+    
+    RepatchBuffer repatchBuffer(codeBlock);
+    repatchBuffer.relink(
         exit.codeLocationForRepatch(codeBlock), CodeLocationLabel(exit.m_code.code()));
     
     return exit.m_code.code().executableAddress();