58 cl::desc(
"Enable the machine combiner pass"),
63 cl::desc(
"Enable the tile register allocation pass"),
114 if (TT.isOSBinFormatMachO()) {
116 return std::make_unique<X86_64MachoTargetObjectFile>();
117 return std::make_unique<TargetLoweringObjectFileMachO>();
120 if (TT.isOSBinFormatCOFF())
121 return std::make_unique<TargetLoweringObjectFileCOFF>();
124 return std::make_unique<X86_64ELFTargetObjectFile>();
125 return std::make_unique<X86ELFTargetObjectFile>();
129 std::optional<Reloc::Model> RM) {
140 if (TT.isOSDarwin()) {
145 if (TT.isOSWindows() &&
is64Bit)
157 if (!TT.isOSDarwin())
172 bool Is64Bit = TT.isX86_64();
188 std::optional<Reloc::Model>
RM,
189 std::optional<CodeModel::Model> CM,
200 if (TT.isPS() || TT.isOSBinFormatMachO()) {
201 this->Options.TrapUnreachable = true;
202 this->Options.NoTrapAfterNoreturn = TT.isOSBinFormatMachO();
217 Attribute CPUAttr =
F.getFnAttribute(
"target-cpu");
218 Attribute TuneAttr =
F.getFnAttribute(
"tune-cpu");
219 Attribute FSAttr =
F.getFnAttribute(
"target-features");
227 : CPU ==
"x86-64" ?
"generic"
239 unsigned PreferVectorWidthOverride = 0;
240 Attribute PreferVecWidthAttr =
F.getFnAttribute(
"prefer-vector-width");
241 if (PreferVecWidthAttr.
isValid()) {
247 PreferVectorWidthOverride = Width;
252 unsigned RequiredVectorWidth = UINT32_MAX;
253 Attribute MinLegalVecWidthAttr =
F.getFnAttribute(
"min-legal-vector-width");
254 if (MinLegalVecWidthAttr.
isValid()) {
260 RequiredVectorWidth = Width;
271 unsigned FSStart =
Key.size();
278 bool SoftFloat =
F.getFnAttribute(
"use-soft-float").getValueAsBool();
282 Key += FS.empty() ?
"+soft-float" :
"+soft-float,";
288 FS =
Key.substr(FSStart);
290 auto &
I = SubtargetMap[
Key];
296 I = std::make_unique<X86Subtarget>(
298 MaybeAlign(
F.getParent()->getOverrideStackAlignment()),
299 PreferVectorWidthOverride, RequiredVectorWidth);
323 unsigned DestAS)
const {
324 assert(SrcAS != DestAS &&
"Expected different address spaces!");
327 return SrcAS < 256 && DestAS < 256;
371 void addIRPasses()
override;
372 bool addInstSelector()
override;
373 bool addIRTranslator()
override;
374 bool addLegalizeMachineIR()
override;
375 bool addRegBankSelect()
override;
376 bool addGlobalInstructionSelect()
override;
377 bool addILPOpts()
override;
378 bool addPreISel()
override;
379 void addMachineSSAOptimization()
override;
380 void addPreRegAlloc()
override;
381 bool addPostFastRegAllocRewrite()
override;
382 void addPostRegAlloc()
override;
383 void addPreEmitPass()
override;
384 void addPreEmitPass2()
override;
385 void addPreSched2()
override;
386 bool addRegAssignAndRewriteOptimized()
override;
388 std::unique_ptr<CSEConfigBase> getCSEConfig()
const override;
394 X86ExecutionDomainFix() : ExecutionDomainFix(
ID,
X86::VR128XRegClass) {}
395 StringRef getPassName()
const override {
396 return "X86 Execution Dependency Fix";
399char X86ExecutionDomainFix::ID;
404 "X86 Execution Domain Fix",
false,
false)
410 return new X86PassConfig(*
this, PM);
420void X86PassConfig::addIRPasses() {
441 const Triple &TT = TM->getTargetTriple();
442 if (TT.isOSWindows()) {
450 if (
TM->Options.JMCInstrument)
454bool X86PassConfig::addInstSelector() {
459 if (
TM->getTargetTriple().isOSBinFormatELF() &&
468bool X86PassConfig::addIRTranslator() {
473bool X86PassConfig::addLegalizeMachineIR() {
478bool X86PassConfig::addRegBankSelect() {
483bool X86PassConfig::addGlobalInstructionSelect() {
486 if (isGlobalISelAbortEnabled())
491bool X86PassConfig::addILPOpts() {
499bool X86PassConfig::addPreISel() {
502 if (
TT.isOSWindows() &&
TT.isX86_32())
507void X86PassConfig::addPreRegAlloc() {
528void X86PassConfig::addMachineSSAOptimization() {
533void X86PassConfig::addPostRegAlloc() {
544void X86PassConfig::addPreSched2() {
549void X86PassConfig::addPreEmitPass() {
551 addPass(
new X86ExecutionDomainFix());
572void X86PassConfig::addPreEmitPass2() {
591 if (
TT.isOSWindows() &&
TT.isX86_64())
597 if (!
TT.isOSDarwin() &&
598 (!
TT.isOSWindows() ||
602 if (
TT.isOSWindows()) {
620 return M->getModuleFlag(
"kcfi") ||
622 (
M->getFunction(
"objc_retainAutoreleasedReturnValue") ||
623 M->getFunction(
"objc_unsafeClaimAutoreleasedReturnValue")));
628 if (
TT.isOSWindows() &&
TT.isX86_64())
632bool X86PassConfig::addPostFastRegAllocRewrite() {
637std::unique_ptr<CSEConfigBase> X86PassConfig::getCSEConfig()
const {
648bool X86PassConfig::addRegAssignAndRewriteOptimized() {
unsigned const MachineRegisterInfo * MRI
assert(UImm &&(UImm !=~static_cast< T >(0)) &&"Invalid immediate!")
static std::unique_ptr< TargetLoweringObjectFile > createTLOF(const Triple &TT)
This file contains the simple types necessary to represent the attributes associated with functions a...
Provides analysis for continuously CSEing during GISel passes.
This file describes how to lower LLVM calls to machine code calls.
This file declares the IRTranslator pass.
Register const TargetRegisterInfo * TRI
static cl::opt< bool > EnableMachineCombinerPass("ppc-machine-combiner", cl::desc("Enable the machine combiner pass"), cl::init(true), cl::Hidden)
#define INITIALIZE_PASS_DEPENDENCY(depName)
#define INITIALIZE_PASS_END(passName, arg, name, cfg, analysis)
#define INITIALIZE_PASS_BEGIN(passName, arg, name, cfg, analysis)
This file describes the interface of the MachineFunctionPass responsible for assigning the generic vi...
const GCNTargetMachine & getTM(const GCNSubtarget *STI)
This file defines the SmallString class.
static TableGen::Emitter::Opt Y("gen-skeleton-entry", EmitSkeleton, "Generate example skeleton entry")
static TableGen::Emitter::OptClass< SkeletonEmitter > X("gen-skeleton-class", "Generate example skeleton class")
Target-Independent Code Generator Pass Configuration Options pass.
static std::unique_ptr< TargetLoweringObjectFile > createTLOF()
#define LLVM_C_ABI
LLVM_C_ABI is the export/visibility macro used to mark symbols declared in llvm-c as exported when bu...
static bool is64Bit(const char *name)
static cl::opt< bool > EnableTileRAPass("x86-tile-ra", cl::desc("Enable the tile register allocation pass"), cl::init(true), cl::Hidden)
static cl::opt< bool > EnableMachineCombinerPass("x86-machine-combiner", cl::desc("Enable the machine combiner pass"), cl::init(true), cl::Hidden)
static CodeModel::Model getEffectiveX86CodeModel(const Triple &TT, std::optional< CodeModel::Model > CM, bool JIT)
static bool onlyAllocateTileRegisters(const TargetRegisterInfo &TRI, const MachineRegisterInfo &MRI, const Register Reg)
LLVM_C_ABI void LLVMInitializeX86Target()
Functions, function parameters, and return types can have attributes to indicate how they should be t...
LLVM_ABI StringRef getValueAsString() const
Return the attribute's value as a string.
bool isValid() const
Return true if the attribute is any kind of attribute.
CodeGenTargetMachineImpl(const Target &T, StringRef DataLayoutString, const Triple &TT, StringRef CPU, StringRef FS, const TargetOptions &Options, Reloc::Model RM, CodeModel::Model CM, CodeGenOptLevel OL)
virtual void reset()
Reset internal state.
Lightweight error class with error context and mandatory checking.
This pass is responsible for selecting generic machine instructions to target-specific instructions.
This class is intended to be used as a base class for asm properties and features specific to the tar...
ExceptionHandling getExceptionHandlingType() const
Function & getFunction()
Return the LLVM function that this machine code represents.
Ty * getInfo()
getInfo - Keep track of various per-function pieces of information for backends that would like to do...
MachineRegisterInfo - Keep track of information for virtual and physical registers,...
A Module instance is used to store all the information related to an LLVM module.
PassRegistry - This class manages the registration and intitialization of the pass subsystem as appli...
static LLVM_ABI PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
This pass implements the reg bank selector pass used in the GlobalISel pipeline.
Wrapper class representing virtual and physical registers.
Instances of this class encapsulate one diagnostic report, allowing printing to a raw_ostream as a ca...
Represents a range in source code.
A ScheduleDAG for scheduling lists of MachineInstr.
ScheduleDAGMILive is an implementation of ScheduleDAGInstrs that schedules machine instructions while...
ScheduleDAGMI is an implementation of ScheduleDAGInstrs that simply schedules machine instructions ac...
void addMutation(std::unique_ptr< ScheduleDAGMutation > Mutation)
Add a postprocessing step to the DAG builder.
SmallString - A SmallString is just a SmallVector with methods and accessors that make it work better...
StringRef - Represent a constant reference to a string, i.e.
bool getAsInteger(unsigned Radix, T &Result) const
Parse the current string as an integer of the specified radix.
void setSupportsDebugEntryValues(bool Enable)
Triple TargetTriple
Triple string, CPU name, and target feature strings the TargetMachine instance is created with.
const Triple & getTargetTriple() const
void setMachineOutliner(bool Enable)
unsigned getPointerSize(unsigned AS) const
Get the pointer size for this target.
std::unique_ptr< const MCSubtargetInfo > STI
void resetTargetOptions(const Function &F) const
Reset the target options based on the function's attributes.
Target-Independent Code Generator Pass Configuration Options.
virtual void addIRPasses()
Add common target configurable passes that perform LLVM IR to IR transforms following machine indepen...
virtual void addMachineSSAOptimization()
addMachineSSAOptimization - Add standard passes that optimize machine instructions in SSA form.
virtual bool addRegAssignAndRewriteOptimized()
TargetRegisterInfo base class - We assume that the target defines a static array of TargetRegisterDes...
TargetSubtargetInfo - Generic base class for all target subtargets.
Target - Wrapper for Target specific information.
Triple - Helper class for working with autoconf configuration names.
X86MachineFunctionInfo - This class is derived from MachineFunction and contains private X86 target-s...
bool isNoopAddrSpaceCast(unsigned SrcAS, unsigned DestAS) const override
Returns true if a cast between SrcAS and DestAS is a noop.
MachineFunctionInfo * createMachineFunctionInfo(BumpPtrAllocator &Allocator, const Function &F, const TargetSubtargetInfo *STI) const override
Create the target's instance of MachineFunctionInfo.
yaml::MachineFunctionInfo * convertFuncInfoToYAML(const MachineFunction &MF) const override
Allocate and initialize an instance of the YAML representation of the MachineFunctionInfo.
const X86Subtarget * getSubtargetImpl() const =delete
ScheduleDAGInstrs * createMachineScheduler(MachineSchedContext *C) const override
Create an instance of ScheduleDAGInstrs to be run within the standard MachineScheduler pass for this ...
ScheduleDAGInstrs * createPostMachineScheduler(MachineSchedContext *C) const override
Similar to createMachineScheduler but used when postRA machine scheduling is enabled.
TargetPassConfig * createPassConfig(PassManagerBase &PM) override
Create a pass configuration object to be used by addPassToEmitX methods for generating a pipeline of ...
bool parseMachineFunctionInfo(const yaml::MachineFunctionInfo &, PerFunctionMIParsingState &PFS, SMDiagnostic &Error, SMRange &SourceRange) const override
Parse out the target's MachineFunctionInfo from the YAML reprsentation.
~X86TargetMachine() override
TargetTransformInfo getTargetTransformInfo(const Function &F) const override
Get a TargetTransformInfo implementation for the target.
yaml::MachineFunctionInfo * createDefaultFuncInfoYAML() const override
Allocate and return a default initialized instance of the YAML representation for the MachineFunction...
X86TargetMachine(const Target &T, const Triple &TT, StringRef CPU, StringRef FS, const TargetOptions &Options, std::optional< Reloc::Model > RM, std::optional< CodeModel::Model > CM, CodeGenOptLevel OL, bool JIT)
Create an X86 target.
PassManagerBase - An abstract interface to allow code to add passes to a pass manager without having ...
unsigned ID
LLVM IR allows to use arbitrary numbers as calling convention identifiers.
@ C
The default llvm calling convention, compatible with C.
@ X86
Windows x64, Windows Itanium (IA-64)
initializer< Ty > init(const Ty &Val)
This is an optimization pass for GlobalISel generic memory operations.
FunctionPass * createX86FloatingPointStackifierPass()
This function returns a pass which converts floating-point register references and pseudo instruction...
ScheduleDAGMILive * createSchedLive(MachineSchedContext *C)
Create the standard converging machine scheduler.
LLVM_ABI FunctionPass * createIndirectBrExpandPass()
FunctionPass * createX86WinEHStatePass()
Return an IR pass that inserts EH registration stack objects and explicit EH state updates.
void initializeX86TileConfigPass(PassRegistry &)
void initializeX86PartialReductionPass(PassRegistry &)
FunctionPass * createX86SuppressAPXForRelocationPass()
void initializeX86CallFrameOptimizationPass(PassRegistry &)
LLVM_ABI ModulePass * createJMCInstrumenterPass()
JMC instrument pass.
void initializeFixupBWInstPassPass(PassRegistry &)
void initializeX86LoadValueInjectionRetHardeningPassPass(PassRegistry &)
FunctionPass * createX86LoadValueInjectionLoadHardeningPass()
FunctionPass * createX86IssueVZeroUpperPass()
This pass inserts AVX vzeroupper instructions before each call to avoid transition penalty between fu...
LLVM_ABI FunctionPass * createGreedyRegisterAllocator()
Greedy register allocation pass - This pass implements a global register allocator for optimized buil...
void initializeX86ArgumentStackSlotPassPass(PassRegistry &)
void initializeX86SpeculativeLoadHardeningPassPass(PassRegistry &)
void initializeWinEHStatePassPass(PassRegistry &)
FunctionPass * createX86InsertPrefetchPass()
This pass applies profiling information to insert cache prefetches.
@ DwarfCFI
DWARF-like instruction based exceptions.
LLVM_ABI FunctionPass * createPseudoProbeInserter()
This pass inserts pseudo probe annotation for callsite profiling.
LLVM_ABI FunctionPass * createX86LowerAMXIntrinsicsPass()
The pass transforms amx intrinsics to scalar operation if the function has optnone attribute or it is...
Target & getTheX86_32Target()
FunctionPass * createX86GlobalBaseRegPass()
This pass initializes a global base register for PIC on x86-32.
FunctionPass * createX86FixupBWInsts()
Return a Machine IR pass that selectively replaces certain byte and word instructions by equivalent 3...
void initializeX86LowerAMXIntrinsicsLegacyPassPass(PassRegistry &)
FunctionPass * createX86DomainReassignmentPass()
Return a Machine IR pass that reassigns instruction chains from one domain to another,...
FunctionPass * createX86LoadValueInjectionRetHardeningPass()
FunctionPass * createX86SpeculativeExecutionSideEffectSuppression()
FunctionPass * createCleanupLocalDynamicTLSPass()
This pass combines multiple accesses to local-dynamic TLS variables so that the TLS base address for ...
FunctionPass * createX86FlagsCopyLoweringPass()
Return a pass that lowers EFLAGS copy pseudo instructions.
void initializeX86FastTileConfigPass(PassRegistry &)
FunctionPass * createCFGuardDispatchPass()
Insert Control FLow Guard dispatches on indirect function calls.
LLVM_ABI std::unique_ptr< CSEConfigBase > getStandardCSEConfigForOpt(CodeGenOptLevel Level)
FunctionPass * createX86CompressEVEXPass()
This pass compress instructions from EVEX space to legacy/VEX/EVEX space when possible in order to re...
void initializeX86ExpandPseudoPass(PassRegistry &)
void initializeX86AvoidTrailingCallPassPass(PassRegistry &)
FunctionPass * createX86ArgumentStackSlotPass()
void initializeX86PreTileConfigPass(PassRegistry &)
LLVM_ABI char & EarlyIfConverterLegacyID
EarlyIfConverter - This pass performs if-conversion on SSA form by inserting cmov instructions.
FunctionPass * createX86CmovConverterPass()
This pass converts X86 cmov instructions into branch when profitable.
FunctionPass * createX86TileConfigPass()
Return a pass that config the tile registers.
FunctionPass * createX86PadShortFunctions()
Return a pass that pads short functions with NOOPs.
void initializeX86DomainReassignmentPass(PassRegistry &)
void initializeX86LoadValueInjectionLoadHardeningPassPass(PassRegistry &)
void initializeX86SuppressAPXForRelocationPassPass(PassRegistry &)
FunctionPass * createX86FastPreTileConfigPass()
Return a pass that preconfig the tile registers before fast reg allocation.
std::unique_ptr< ScheduleDAGMutation > createX86MacroFusionDAGMutation()
Note that you have to add: DAG.addMutation(createX86MacroFusionDAGMutation()); to X86TargetMachine::c...
void initializeX86AvoidSFBPassPass(PassRegistry &)
FunctionPass * createX86LowerTileCopyPass()
Return a pass that lower the tile copy instruction.
LLVM_ABI char & MachineCombinerID
This pass performs instruction combining using trace metrics to estimate critical-path and resource d...
void initializeX86FastPreTileConfigPass(PassRegistry &)
static Reloc::Model getEffectiveRelocModel(std::optional< Reloc::Model > RM)
FunctionPass * createX86SpeculativeLoadHardeningPass()
FunctionPass * createX86FixupSetCC()
Return a pass that transforms setcc + movzx pairs into xor + setcc.
FunctionPass * createX86IndirectBranchTrackingPass()
This pass inserts ENDBR instructions before indirect jump/call destinations as part of CET IBT mechan...
void initializeX86AsmPrinterPass(PassRegistry &)
FunctionPass * createX86InsertX87waitPass()
This pass insert wait instruction after X87 instructions which could raise fp exceptions when strict-...
ScheduleDAGMI * createSchedPostRA(MachineSchedContext *C)
Create a generic scheduler with no vreg liveness or DAG mutation passes.
void initializeX86FixupSetCCPassPass(PassRegistry &)
LLVM_ABI FunctionPass * createKCFIPass()
Lowers KCFI operand bundles for indirect calls.
LLVM_ABI char & LiveRangeShrinkID
LiveRangeShrink pass.
FunctionPass * createX86ExpandPseudoPass()
Return a Machine IR pass that expands X86-specific pseudo instructions into a sequence of actual inst...
FunctionPass * createX86FixupInstTuning()
Return a pass that replaces equivalent slower instructions with faster ones.
void initializeX86WinEHUnwindV2Pass(PassRegistry &)
FunctionPass * createX86ISelDag(X86TargetMachine &TM, CodeGenOptLevel OptLevel)
This pass converts a legalized DAG into a X86-specific DAG, ready for instruction scheduling.
void initializeX86LowerTileCopyPass(PassRegistry &)
void initializeX86OptimizeLEAPassPass(PassRegistry &)
LLVM_ABI void initializePseudoProbeInserterPass(PassRegistry &)
BumpPtrAllocatorImpl BumpPtrAllocator
The standard BumpPtrAllocator which just uses the default template parameters.
CodeGenOptLevel
Code generation optimization level.
LLVM_ABI FunctionPass * createCFGuardLongjmpPass()
Creates CFGuard longjmp target identification pass.
LLVM_ATTRIBUTE_VISIBILITY_DEFAULT AnalysisKey InnerAnalysisManagerProxy< AnalysisManagerT, IRUnitT, ExtraArgTs... >::Key
FunctionPass * createX86FastTileConfigPass()
Return a pass that config the tile registers after fast reg allocation.
FunctionPass * createX86PartialReductionPass()
This pass optimizes arithmetic based on knowledge that is only used by a reduction sequence and is th...
FunctionPass * createX86FixupLEAs()
Return a pass that selectively replaces certain instructions (like add, sub, inc, dec,...
LLVM_ABI FunctionPass * createInterleavedAccessPass()
InterleavedAccess Pass - This pass identifies and matches interleaved memory accesses to target speci...
LLVM_ABI void initializeGlobalISel(PassRegistry &)
Initialize all passes linked into the GlobalISel library.
LLVM_ABI void initializeKCFIPass(PassRegistry &)
void initializeX86FixupInstTuningPassPass(PassRegistry &)
void initializeX86LowerAMXTypeLegacyPassPass(PassRegistry &)
void initializeX86CmovConverterPassPass(PassRegistry &)
LLVM_ABI FunctionPass * createBreakFalseDeps()
Creates Break False Dependencies pass.
FunctionPass * createX86CallFrameOptimization()
Return a pass that optimizes the code-size of x86 call sequences.
void initializeX86FlagsCopyLoweringPassPass(PassRegistry &)
void initializeFPSPass(PassRegistry &)
LLVM_ABI FunctionPass * createUnpackMachineBundles(std::function< bool(const MachineFunction &)> Ftor)
FunctionPass * createX86WinEHUnwindV2Pass()
// Analyzes and emits pseudos to support Win x64 Unwind V2.
FunctionPass * createX86AvoidTrailingCallPass()
Return a pass that inserts int3 at the end of the function if it ends with a CALL instruction.
FunctionPass * createX86DynAllocaExpander()
Return a pass that expands DynAlloca pseudo-instructions.
void initializeX86SpeculativeExecutionSideEffectSuppressionPass(PassRegistry &)
void initializeCompressEVEXPassPass(PassRegistry &)
FunctionPass * createCFGuardCheckPass()
Insert Control FLow Guard checks on indirect function calls.
LLVM_ABI FunctionPass * createEHContGuardTargetsPass()
Creates Windows EH Continuation Guard target identification pass.
FunctionPass * createX86OptimizeLEAs()
Return a pass that removes redundant LEA instructions and redundant address recalculations.
void initializeX86FixupVectorConstantsPassPass(PassRegistry &)
LLVM_ABI FunctionPass * createX86LowerAMXTypePass()
The pass transforms load/store <256 x i32> to AMX load/store intrinsics or split the data to two <128...
FunctionPass * createX86IndirectThunksPass()
This pass creates the thunks for the retpoline feature.
LLVM_ABI FunctionPass * createAtomicExpandLegacyPass()
AtomicExpandPass - At IR level this pass replace atomic instructions with __atomic_* library calls,...
void initializeX86DynAllocaExpanderPass(PassRegistry &)
Target & getTheX86_64Target()
FunctionPass * createX86FixupVectorConstants()
Return a pass that reduces the size of vector constant pool loads.
LLVM_ABI FunctionPass * createCFIInstrInserter()
Creates CFI Instruction Inserter pass.
void initializeX86ExecutionDomainFixPass(PassRegistry &)
FunctionPass * createX86PreTileConfigPass()
Return a pass that insert pseudo tile config instruction.
FunctionPass * createX86ReturnThunksPass()
This pass replaces ret instructions with jmp's to __x86_return thunk.
FunctionPass * createX86AvoidStoreForwardingBlocks()
Return a pass that avoids creating store forward block issues in the hardware.
void initializeX86ReturnThunksPass(PassRegistry &)
void initializeX86DAGToDAGISelLegacyPass(PassRegistry &)
FunctionPass * createX86DiscriminateMemOpsPass()
This pass ensures instructions featuring a memory operand have distinctive <LineNumber,...
void initializeFixupLEAPassPass(PassRegistry &)
LLVM_ABI void reportFatalUsageError(Error Err)
Report a fatal error that does not indicate a bug in LLVM.
MachineFunctionInfo - This class can be derived from and used by targets to hold private target-speci...
static FuncInfoTy * create(BumpPtrAllocator &Allocator, const Function &F, const SubtargetTy *STI)
Factory function: default behavior is to call new using the supplied allocator.
MachineSchedContext provides enough context from the MachineScheduler pass for the target to instanti...
This struct is a compact representation of a valid (power of two) or undefined (0) alignment.
RegisterTargetMachine - Helper template for registering a target machine implementation,...
Targets should override this in a way that mirrors the implementation of llvm::MachineFunctionInfo.