| /* | 
 |  * Copyright (C) 2013-2019 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 "FTLOSRExitCompiler.h" | 
 |  | 
 | #if ENABLE(FTL_JIT) | 
 |  | 
 | #include "BytecodeStructs.h" | 
 | #include "DFGOSRExitCompilerCommon.h" | 
 | #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" | 
 |  | 
 | 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 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) | 
 | { | 
 |     // 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(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.restoreCalleeSavesFromEntryFrameCalleeSavesBuffer(vm->topEntryFrame); | 
 |         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)); | 
 |     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); | 
 |     }; | 
 |      | 
 |     // 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(). | 
 |  | 
 |     saveAllRegisters(jit, registerScratch); | 
 |      | 
 |     if (validateDFGDoesGC) { | 
 |         // We're about to exit optimized code. So, there's no longer any optimized | 
 |         // code running that expects no GC. We need to set this before object | 
 |         // materialization below. | 
 |  | 
 |         // Even though we set Heap::m_expectDoesGC in compileFTLOSRExit(), we also need | 
 |         // to set it here because compileFTLOSRExit() is only called on the first time | 
 |         // we exit from this site, but all subsequent exits will take this compiled | 
 |         // ramp without calling compileFTLOSRExit() first. | 
 |         jit.store8(CCallHelpers::TrustedImm32(true), vm->heap.addressOfExpectDoesGC()); | 
 |     } | 
 |  | 
 |     // Bring the stack back into a sane form and assert that it's sane. | 
 |     jit.popToRestore(GPRInfo::regT0); | 
 |     jit.checkStackPointerAlignment(); | 
 |      | 
 |     if (UNLIKELY(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 | 
 |     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); | 
 |         reboxAccordingToFormat( | 
 |             exit.m_descriptor->m_profileDataFormat, jit, GPRInfo::regT0, GPRInfo::regT1, GPRInfo::regT2); | 
 |          | 
 |         if (exit.m_kind == BadCache || exit.m_kind == BadIndexingType) { | 
 |             CodeOrigin codeOrigin = exit.m_codeOriginForExitProfile; | 
 |             CodeBlock* codeBlock = jit.baselineCodeBlockFor(codeOrigin); | 
 |             if (ArrayProfile* arrayProfile = codeBlock->getArrayProfile(codeOrigin.bytecodeIndex())) { | 
 |                 const Instruction* instruction = codeBlock->instructions().at(codeOrigin.bytecodeIndex()).ptr(); | 
 |                 CCallHelpers::Jump skipProfile; | 
 |                 if (instruction->is<OpGetById>()) { | 
 |                     auto& metadata = instruction->as<OpGetById>().metadata(codeBlock); | 
 |                     skipProfile = jit.branch8(CCallHelpers::NotEqual, CCallHelpers::AbsoluteAddress(&metadata.m_modeMetadata.mode), CCallHelpers::TrustedImm32(static_cast<uint8_t>(GetByIdMode::ArrayLength))); | 
 |                 } | 
 |  | 
 |                 jit.load32(MacroAssembler::Address(GPRInfo::regT0, JSCell::structureIDOffset()), GPRInfo::regT1); | 
 |                 jit.store32(GPRInfo::regT1, arrayProfile->addressOfLastSeenStructureID()); | 
 |  | 
 |                 jit.load8(MacroAssembler::Address(GPRInfo::regT0, JSCell::typeInfoTypeOffset()), GPRInfo::regT2); | 
 |                 jit.sub32(MacroAssembler::TrustedImm32(FirstTypedArrayType), GPRInfo::regT2); | 
 |                 auto notTypedArray = jit.branch32(MacroAssembler::AboveOrEqual, GPRInfo::regT2, MacroAssembler::TrustedImm32(NumberOfTypedArrayTypesExcludingDataView)); | 
 |                 jit.move(MacroAssembler::TrustedImmPtr(typedArrayModes), GPRInfo::regT1); | 
 |                 jit.load32(MacroAssembler::BaseIndex(GPRInfo::regT1, GPRInfo::regT2, MacroAssembler::TimesFour), GPRInfo::regT2); | 
 |                 auto storeArrayModes = jit.jump(); | 
 |  | 
 |                 notTypedArray.link(&jit); | 
 |                 jit.load8(MacroAssembler::Address(GPRInfo::regT0, JSCell::indexingTypeAndMiscOffset()), GPRInfo::regT1); | 
 |                 jit.and32(MacroAssembler::TrustedImm32(IndexingModeMask), GPRInfo::regT1); | 
 |                 jit.move(MacroAssembler::TrustedImm32(1), GPRInfo::regT2); | 
 |                 jit.lshift32(GPRInfo::regT1, GPRInfo::regT2); | 
 |                 storeArrayModes.link(&jit); | 
 |                 jit.or32(GPRInfo::regT2, MacroAssembler::AbsoluteAddress(arrayProfile->addressOfArrayModes())); | 
 |  | 
 |                 if (skipProfile.isSet()) | 
 |                     skipProfile.link(&jit); | 
 |             } | 
 |         } | 
 |  | 
 |         if (exit.m_descriptor->m_valueProfile) | 
 |             exit.m_descriptor->m_valueProfile.emitReportValue(jit, JSValueRegs(GPRInfo::regT0)); | 
 |     } | 
 |  | 
 |     // 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); | 
 |             } | 
 |              | 
 |             static_assert(FunctionTraits<decltype(operationMaterializeObjectInOSR)>::arity < GPRInfo::numberOfArgumentRegisters, "This call assumes that we don't pass arguments on the stack."); | 
 |             jit.setupArguments<decltype(operationMaterializeObjectInOSR)>( | 
 |                 CCallHelpers::TrustedImmPtr(materialization), | 
 |                 CCallHelpers::TrustedImmPtr(materializationArguments)); | 
 |             jit.move(CCallHelpers::TrustedImmPtr(tagCFunctionPtr<OperationPtrTag>(operationMaterializeObjectInOSR)), GPRInfo::nonArgGPR0); | 
 |             jit.call(GPRInfo::nonArgGPR0, OperationPtrTag); | 
 |             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); | 
 |         } | 
 |  | 
 |         static_assert(FunctionTraits<decltype(operationPopulateObjectInOSR)>::arity < GPRInfo::numberOfArgumentRegisters, "This call assumes that we don't pass arguments on the stack."); | 
 |         jit.setupArguments<decltype(operationPopulateObjectInOSR)>( | 
 |             CCallHelpers::TrustedImmPtr(materialization), | 
 |             CCallHelpers::TrustedImmPtr(materializationToPointer.get(materialization)), | 
 |             CCallHelpers::TrustedImmPtr(materializationArguments)); | 
 |         jit.move(CCallHelpers::TrustedImmPtr(tagCFunctionPtr<OperationPtrTag>(operationPopulateObjectInOSR)), GPRInfo::nonArgGPR0); | 
 |         jit.call(GPRInfo::nonArgGPR0, OperationPtrTag); | 
 |     } | 
 |  | 
 |     // 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. | 
 |      | 
 |     for (unsigned index = exit.m_descriptor->m_values.size(); index--;) { | 
 |         recoverValue(exit.m_descriptor->m_values[index]); | 
 |         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); | 
 |     } | 
 |      | 
 |     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(); | 
 |     const RegisterAtOffsetList* baselineCalleeSaves = baselineCodeBlock->calleeSaveRegisters(); | 
 |     RegisterAtOffsetList* vmCalleeSaves = RegisterSet::vmCalleeSaveRegisterOffsets(); | 
 |     RegisterSet vmCalleeSavesToSkip = RegisterSet::stackRegisters(); | 
 |     if (exit.isExceptionHandler()) { | 
 |         jit.loadPtr(&vm->topEntryFrame, GPRInfo::regT1); | 
 |         jit.addPtr(CCallHelpers::TrustedImm32(EntryFrame::calleeSaveRegistersBufferOffset()), 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); | 
 |         const 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; | 
 |  | 
 |         jit.load64(scratch + index, GPRInfo::regT0); | 
 |         jit.store64(GPRInfo::regT0, AssemblyHelpers::addressFor(reg)); | 
 |     } | 
 |      | 
 |     handleExitCounts(jit, exit); | 
 |     reifyInlinedCallFrames(jit, exit); | 
 |     adjustAndJumpToTarget(*vm, jit, exit); | 
 |      | 
 |     LinkBuffer patchBuffer(jit, codeBlock); | 
 |     exit.m_code = FINALIZE_CODE_IF( | 
 |         shouldDumpDisassembly() || Options::verboseOSR() || Options::verboseFTLOSRExit(), | 
 |         patchBuffer, OSRExitPtrTag, | 
 |         "FTL OSR exit #%u (%s, %s) from %s, with operands = %s", | 
 |             exitID, toCString(exit.m_codeOrigin).data(), | 
 |             exitKindToString(exit.m_kind), toCString(*codeBlock).data(), | 
 |             toCString(ignoringContext<DumpContext>(exit.m_descriptor->m_values)).data() | 
 |         ); | 
 | } | 
 |  | 
 | extern "C" void* compileFTLOSRExit(ExecState* exec, unsigned exitID) | 
 | { | 
 |     if (shouldDumpDisassembly() || Options::verboseOSR() || Options::verboseFTLOSRExit()) | 
 |         dataLog("Compiling OSR exit with exitID = ", exitID, "\n"); | 
 |  | 
 |     VM& vm = exec->vm(); | 
 |  | 
 |     if (validateDFGDoesGC) { | 
 |         // We're about to exit optimized code. So, there's no longer any optimized | 
 |         // code running that expects no GC. | 
 |         vm.heap.setExpectDoesGC(true); | 
 |     } | 
 |  | 
 |     if (vm.callFrameForCatch) | 
 |         RELEASE_ASSERT(vm.callFrameForCatch == exec); | 
 |      | 
 |     CodeBlock* codeBlock = exec->codeBlock(); | 
 |      | 
 |     ASSERT(codeBlock); | 
 |     ASSERT(codeBlock->jitType() == JITType::FTLJIT); | 
 |      | 
 |     // It's sort of preferable that we don't GC while in here. Anyways, doing so wouldn't | 
 |     // really be profitable. | 
 |     DeferGCForAWhile deferGC(vm.heap); | 
 |  | 
 |     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( | 
 |         exit.codeLocationForRepatch(codeBlock), CodeLocationLabel<OSRExitPtrTag>(exit.m_code.code())); | 
 |      | 
 |     return exit.m_code.code().executableAddress(); | 
 | } | 
 |  | 
 | } } // namespace JSC::FTL | 
 |  | 
 | #endif // ENABLE(FTL_JIT) | 
 |  |