lib/Transforms/Instrumentation/InstrProfiling.cpp - platform/external/llvm - Git at Google

 //===-- InstrProfiling.cpp - Frontend instrumentation based profiling -----===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This pass lowers instrprof_* intrinsics emitted by a frontend for profiling.
 // It also builds the data structures and initialization code needed for
 // updating execution counts and emitting the profile at runtime.
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/ADT/Triple.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Module.h"
 #include "llvm/ProfileData/InstrProf.h"
 #include "llvm/Transforms/Instrumentation.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"

 using namespace llvm;

 #define DEBUG_TYPE "instrprof"

 namespace {

 class InstrProfiling : public ModulePass {
 public:
   static char ID;

   InstrProfiling() : ModulePass(ID) {}

   InstrProfiling(const InstrProfOptions &Options)
       : ModulePass(ID), Options(Options) {}

   const char *getPassName() const override {
     return "Frontend instrumentation-based coverage lowering";
   }

   bool runOnModule(Module &M) override;

   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.setPreservesCFG();
   }

 private:
   InstrProfOptions Options;
   Module *M;
   typedef struct PerFunctionProfileData {
     uint32_t NumValueSites[IPVK_Last+1];
     GlobalVariable* RegionCounters;
     GlobalVariable* DataVar;
     PerFunctionProfileData() : RegionCounters(nullptr), DataVar(nullptr) {
       memset(NumValueSites, 0, sizeof(uint32_t) * (IPVK_Last+1));
     }
   } PerFunctionProfileData;
   DenseMap<GlobalVariable *, PerFunctionProfileData> ProfileDataMap;
   std::vector<Value *> UsedVars;

   bool isMachO() const {
     return Triple(M->getTargetTriple()).isOSBinFormatMachO();
   }

   /// Get the section name for the counter variables.
   StringRef getCountersSection() const {
     return getInstrProfCountersSectionName(isMachO());
   }

   /// Get the section name for the name variables.
   StringRef getNameSection() const {
     return getInstrProfNameSectionName(isMachO());
   }

   /// Get the section name for the profile data variables.
   StringRef getDataSection() const {
     return getInstrProfDataSectionName(isMachO());
   }

   /// Get the section name for the coverage mapping data.
   StringRef getCoverageSection() const {
     return getInstrProfCoverageSectionName(isMachO());
   }

   /// Count the number of instrumented value sites for the function.
   void computeNumValueSiteCounts(InstrProfValueProfileInst *Ins);

   /// Replace instrprof_value_profile with a call to runtime library.
   void lowerValueProfileInst(InstrProfValueProfileInst *Ins);

   /// Replace instrprof_increment with an increment of the appropriate value.
   void lowerIncrement(InstrProfIncrementInst *Inc);

   /// Set up the section and uses for coverage data and its references.
   void lowerCoverageData(GlobalVariable *CoverageData);

   /// Get the region counters for an increment, creating them if necessary.
   ///
   /// If the counter array doesn't yet exist, the profile data variables
   /// referring to them will also be created.
   GlobalVariable *getOrCreateRegionCounters(InstrProfIncrementInst *Inc);

   /// Emit runtime registration functions for each profile data variable.
   void emitRegistration();

   /// Emit the necessary plumbing to pull in the runtime initialization.
   void emitRuntimeHook();

   /// Add uses of our data variables and runtime hook.
   void emitUses();

   /// Create a static initializer for our data, on platforms that need it,
   /// and for any profile output file that was specified.
   void emitInitialization();
 };

 } // anonymous namespace

 char InstrProfiling::ID = 0;
 INITIALIZE_PASS(InstrProfiling, "instrprof",
                 "Frontend instrumentation-based coverage lowering.", false,
                 false)

 ModulePass *llvm::createInstrProfilingPass(const InstrProfOptions &Options) {
   return new InstrProfiling(Options);
 }

 bool InstrProfiling::runOnModule(Module &M) {
   bool MadeChange = false;

   this->M = &M;
   ProfileDataMap.clear();
   UsedVars.clear();

   // We did not know how many value sites there would be inside
   // the instrumented function. This is counting the number of instrumented
   // target value sites to enter it as field in the profile data variable.
   for (Function &F : M)
     for (BasicBlock &BB : F)
       for (auto I = BB.begin(), E = BB.end(); I != E;)
         if (auto *Ind = dyn_cast<InstrProfValueProfileInst>(I++))
           computeNumValueSiteCounts(Ind);

   for (Function &F : M)
     for (BasicBlock &BB : F)
       for (auto I = BB.begin(), E = BB.end(); I != E;) {
         auto Instr = I++;
         if (auto *Inc = dyn_cast<InstrProfIncrementInst>(Instr)) {
           lowerIncrement(Inc);
           MadeChange = true;
         } else if (auto *Ind = dyn_cast<InstrProfValueProfileInst>(Instr)) {
           lowerValueProfileInst(Ind);
           MadeChange = true;
         }
       }

   if (GlobalVariable *Coverage =
           M.getNamedGlobal(getCoverageMappingVarName())) {
     lowerCoverageData(Coverage);
     MadeChange = true;
   }

   if (!MadeChange)
     return false;

   emitRegistration();
   emitRuntimeHook();
   emitUses();
   emitInitialization();
   return true;
 }

 static Constant *getOrInsertValueProfilingCall(Module &M) {
   LLVMContext &Ctx = M.getContext();
   auto *ReturnTy = Type::getVoidTy(M.getContext());
   Type *ParamTypes[] = {
 #define VALUE_PROF_FUNC_PARAM(ParamType, ParamName, ParamLLVMType) ParamLLVMType
 #include "llvm/ProfileData/InstrProfData.inc"
   };
   auto *ValueProfilingCallTy =
       FunctionType::get(ReturnTy, makeArrayRef(ParamTypes), false);
   return M.getOrInsertFunction(getInstrProfValueProfFuncName(),
                                ValueProfilingCallTy);
 }

 void InstrProfiling::computeNumValueSiteCounts(InstrProfValueProfileInst *Ind) {

   GlobalVariable *Name = Ind->getName();
   uint64_t ValueKind = Ind->getValueKind()->getZExtValue();
   uint64_t Index = Ind->getIndex()->getZExtValue();
   auto It = ProfileDataMap.find(Name);
   if (It == ProfileDataMap.end()) {
     PerFunctionProfileData PD;
     PD.NumValueSites[ValueKind] = Index + 1;
     ProfileDataMap[Name] = PD;
   } else if (It->second.NumValueSites[ValueKind] <= Index)
     It->second.NumValueSites[ValueKind] = Index + 1;
 }

 void InstrProfiling::lowerValueProfileInst(InstrProfValueProfileInst *Ind) {

   GlobalVariable *Name = Ind->getName();
   auto It = ProfileDataMap.find(Name);
   assert(It != ProfileDataMap.end() && It->second.DataVar &&
     "value profiling detected in function with no counter incerement");

   GlobalVariable *DataVar = It->second.DataVar;
   uint64_t ValueKind = Ind->getValueKind()->getZExtValue();
   uint64_t Index = Ind->getIndex()->getZExtValue();
   for (uint32_t Kind = IPVK_First; Kind < ValueKind; ++Kind)
     Index += It->second.NumValueSites[Kind];

   IRBuilder<> Builder(Ind);
   Value* Args[3] = {Ind->getTargetValue(),
       Builder.CreateBitCast(DataVar, Builder.getInt8PtrTy()),
       Builder.getInt32(Index)};
   Ind->replaceAllUsesWith(
       Builder.CreateCall(getOrInsertValueProfilingCall(*M), Args));
   Ind->eraseFromParent();
 }

 void InstrProfiling::lowerIncrement(InstrProfIncrementInst *Inc) {
   GlobalVariable *Counters = getOrCreateRegionCounters(Inc);

   IRBuilder<> Builder(Inc);
   uint64_t Index = Inc->getIndex()->getZExtValue();
   Value *Addr = Builder.CreateConstInBoundsGEP2_64(Counters, 0, Index);
   Value *Count = Builder.CreateLoad(Addr, "pgocount");
   Count = Builder.CreateAdd(Count, Builder.getInt64(1));
   Inc->replaceAllUsesWith(Builder.CreateStore(Count, Addr));
   Inc->eraseFromParent();
 }

 void InstrProfiling::lowerCoverageData(GlobalVariable *CoverageData) {
   CoverageData->setSection(getCoverageSection());
   CoverageData->setAlignment(8);

   Constant *Init = CoverageData->getInitializer();
   // We're expecting { i32, i32, i32, i32, [n x { i8*, i32, i32 }], [m x i8] }
   // for some C. If not, the frontend's given us something broken.
   assert(Init->getNumOperands() == 6 && "bad number of fields in coverage map");
   assert(isa<ConstantArray>(Init->getAggregateElement(4)) &&
          "invalid function list in coverage map");
   ConstantArray *Records = cast<ConstantArray>(Init->getAggregateElement(4));
   for (unsigned I = 0, E = Records->getNumOperands(); I < E; ++I) {
     Constant *Record = Records->getOperand(I);
     Value *V = const_cast<Value *>(Record->getOperand(0))->stripPointerCasts();

     assert(isa<GlobalVariable>(V) && "Missing reference to function name");
     GlobalVariable *Name = cast<GlobalVariable>(V);

     // If we have region counters for this name, we've already handled it.
     auto It = ProfileDataMap.find(Name);
     if (It != ProfileDataMap.end())
       if (It->second.RegionCounters)
         continue;

     // Move the name variable to the right section.
     Name->setSection(getNameSection());
     Name->setAlignment(1);
   }
 }

 /// Get the name of a profiling variable for a particular function.
 static std::string getVarName(InstrProfIncrementInst *Inc, StringRef Prefix) {
   StringRef NamePrefix = getInstrProfNameVarPrefix();
   StringRef Name = Inc->getName()->getName().substr(NamePrefix.size());
   return (Prefix + Name).str();
 }

 static inline bool shouldRecordFunctionAddr(Function *F) {
   // Check the linkage
   if (!F->hasLinkOnceLinkage() && !F->hasLocalLinkage() &&
       !F->hasAvailableExternallyLinkage())
     return true;
   // Check uses of this function for other than direct calls or invokes to it.
   return F->hasAddressTaken();
 }

 static inline Comdat *getOrCreateProfileComdat(Module &M,
                                                InstrProfIncrementInst *Inc) {
   // COFF format requires a COMDAT section to have a key symbol with the same
   // name. The linker targeting COFF also requires that the COMDAT section
   // a section is associated to must precede the associating section. For this
   // reason, we must choose the name var's name as the name of the comdat.
   StringRef ComdatPrefix = (Triple(M.getTargetTriple()).isOSBinFormatCOFF()
                                 ? getInstrProfNameVarPrefix()
                                 : getInstrProfComdatPrefix());
   return M.getOrInsertComdat(StringRef(getVarName(Inc, ComdatPrefix)));
 }

 GlobalVariable *
 InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
   GlobalVariable *NamePtr = Inc->getName();
   auto It = ProfileDataMap.find(NamePtr);
   PerFunctionProfileData PD;
   if (It != ProfileDataMap.end()) {
     if (It->second.RegionCounters)
       return It->second.RegionCounters;
     PD = It->second;
   }

   // Move the name variable to the right section. Place them in a COMDAT group
   // if the associated function is a COMDAT. This will make sure that
   // only one copy of counters of the COMDAT function will be emitted after
   // linking.
   Function *Fn = Inc->getParent()->getParent();
   Comdat *ProfileVarsComdat = nullptr;
   if (Fn->hasComdat())
     ProfileVarsComdat = getOrCreateProfileComdat(*M, Inc);
   NamePtr->setSection(getNameSection());
   NamePtr->setAlignment(1);
   NamePtr->setComdat(ProfileVarsComdat);

   uint64_t NumCounters = Inc->getNumCounters()->getZExtValue();
   LLVMContext &Ctx = M->getContext();
   ArrayType *CounterTy = ArrayType::get(Type::getInt64Ty(Ctx), NumCounters);

   // Create the counters variable.
   auto *CounterPtr =
       new GlobalVariable(*M, CounterTy, false, NamePtr->getLinkage(),
                          Constant::getNullValue(CounterTy),
                          getVarName(Inc, getInstrProfCountersVarPrefix()));
   CounterPtr->setVisibility(NamePtr->getVisibility());
   CounterPtr->setSection(getCountersSection());
   CounterPtr->setAlignment(8);
   CounterPtr->setComdat(ProfileVarsComdat);

   // Create data variable.
   auto *Int8PtrTy = Type::getInt8PtrTy(Ctx);
   auto *Int16Ty = Type::getInt16Ty(Ctx);
   auto *Int16ArrayTy = ArrayType::get(Int16Ty, IPVK_Last+1);
   Type *DataTypes[] = {
     #define INSTR_PROF_DATA(Type, LLVMType, Name, Init) LLVMType,
     #include "llvm/ProfileData/InstrProfData.inc"
   };
   auto *DataTy = StructType::get(Ctx, makeArrayRef(DataTypes));

   Constant *FunctionAddr = shouldRecordFunctionAddr(Fn) ?
                            ConstantExpr::getBitCast(Fn, Int8PtrTy) :
                            ConstantPointerNull::get(Int8PtrTy);

   Constant *Int16ArrayVals[IPVK_Last+1];
   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
     Int16ArrayVals[Kind] = ConstantInt::get(Int16Ty, PD.NumValueSites[Kind]);

   Constant *DataVals[] = {
     #define INSTR_PROF_DATA(Type, LLVMType, Name, Init) Init,
     #include "llvm/ProfileData/InstrProfData.inc"
   };
   auto *Data = new GlobalVariable(*M, DataTy, false, NamePtr->getLinkage(),
                                   ConstantStruct::get(DataTy, DataVals),
                                   getVarName(Inc, getInstrProfDataVarPrefix()));
   Data->setVisibility(NamePtr->getVisibility());
   Data->setSection(getDataSection());
   Data->setAlignment(INSTR_PROF_DATA_ALIGNMENT);
   Data->setComdat(ProfileVarsComdat);

   PD.RegionCounters = CounterPtr;
   PD.DataVar = Data;
   ProfileDataMap[NamePtr] = PD;

   // Mark the data variable as used so that it isn't stripped out.
   UsedVars.push_back(Data);

   return CounterPtr;
 }

 void InstrProfiling::emitRegistration() {
   // Don't do this for Darwin.  compiler-rt uses linker magic.
   if (Triple(M->getTargetTriple()).isOSDarwin())
     return;

   // Use linker script magic to get data/cnts/name start/end.
   if (Triple(M->getTargetTriple()).isOSLinux() ||
       Triple(M->getTargetTriple()).isOSFreeBSD())
     return;

   // Construct the function.
   auto *VoidTy = Type::getVoidTy(M->getContext());
   auto *VoidPtrTy = Type::getInt8PtrTy(M->getContext());
   auto *RegisterFTy = FunctionType::get(VoidTy, false);
   auto *RegisterF = Function::Create(RegisterFTy, GlobalValue::InternalLinkage,
                                      getInstrProfRegFuncsName(), M);
   RegisterF->setUnnamedAddr(true);
   if (Options.NoRedZone) RegisterF->addFnAttr(Attribute::NoRedZone);

   auto *RuntimeRegisterTy = FunctionType::get(VoidTy, VoidPtrTy, false);
   auto *RuntimeRegisterF =
       Function::Create(RuntimeRegisterTy, GlobalVariable::ExternalLinkage,
                        getInstrProfRegFuncName(), M);

   IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", RegisterF));
   for (Value *Data : UsedVars)
     IRB.CreateCall(RuntimeRegisterF, IRB.CreateBitCast(Data, VoidPtrTy));
   IRB.CreateRetVoid();
 }

 void InstrProfiling::emitRuntimeHook() {

   // We expect the linker to be invoked with -u<hook_var> flag for linux,
   // for which case there is no need to emit the user function.
   if (Triple(M->getTargetTriple()).isOSLinux())
     return;

   // If the module's provided its own runtime, we don't need to do anything.
   if (M->getGlobalVariable(getInstrProfRuntimeHookVarName())) return;

   // Declare an external variable that will pull in the runtime initialization.
   auto *Int32Ty = Type::getInt32Ty(M->getContext());
   auto *Var =
       new GlobalVariable(*M, Int32Ty, false, GlobalValue::ExternalLinkage,
                          nullptr, getInstrProfRuntimeHookVarName());

   // Make a function that uses it.
   auto *User = Function::Create(FunctionType::get(Int32Ty, false),
                                 GlobalValue::LinkOnceODRLinkage,
                                 getInstrProfRuntimeHookVarUseFuncName(), M);
   User->addFnAttr(Attribute::NoInline);
   if (Options.NoRedZone) User->addFnAttr(Attribute::NoRedZone);
   User->setVisibility(GlobalValue::HiddenVisibility);

   IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", User));
   auto *Load = IRB.CreateLoad(Var);
   IRB.CreateRet(Load);

   // Mark the user variable as used so that it isn't stripped out.
   UsedVars.push_back(User);
 }

 void InstrProfiling::emitUses() {
   if (UsedVars.empty())
     return;

   GlobalVariable *LLVMUsed = M->getGlobalVariable("llvm.used");
   std::vector<Constant *> MergedVars;
   if (LLVMUsed) {
     // Collect the existing members of llvm.used.
     ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
     for (unsigned I = 0, E = Inits->getNumOperands(); I != E; ++I)
       MergedVars.push_back(Inits->getOperand(I));
     LLVMUsed->eraseFromParent();
   }

   Type *i8PTy = Type::getInt8PtrTy(M->getContext());
   // Add uses for our data.
   for (auto *Value : UsedVars)
     MergedVars.push_back(
         ConstantExpr::getBitCast(cast<Constant>(Value), i8PTy));

   // Recreate llvm.used.
   ArrayType *ATy = ArrayType::get(i8PTy, MergedVars.size());
   LLVMUsed =
       new GlobalVariable(*M, ATy, false, GlobalValue::AppendingLinkage,
                          ConstantArray::get(ATy, MergedVars), "llvm.used");
   LLVMUsed->setSection("llvm.metadata");
 }

 void InstrProfiling::emitInitialization() {
   std::string InstrProfileOutput = Options.InstrProfileOutput;

   Constant *RegisterF = M->getFunction(getInstrProfRegFuncsName());
   if (!RegisterF && InstrProfileOutput.empty()) return;

   // Create the initialization function.
   auto *VoidTy = Type::getVoidTy(M->getContext());
   auto *F = Function::Create(FunctionType::get(VoidTy, false),
                              GlobalValue::InternalLinkage,
                              getInstrProfInitFuncName(), M);
   F->setUnnamedAddr(true);
   F->addFnAttr(Attribute::NoInline);
   if (Options.NoRedZone) F->addFnAttr(Attribute::NoRedZone);

   // Add the basic block and the necessary calls.
   IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", F));
   if (RegisterF)
     IRB.CreateCall(RegisterF, {});
   if (!InstrProfileOutput.empty()) {
     auto *Int8PtrTy = Type::getInt8PtrTy(M->getContext());
     auto *SetNameTy = FunctionType::get(VoidTy, Int8PtrTy, false);
     auto *SetNameF = Function::Create(SetNameTy, GlobalValue::ExternalLinkage,
                                       getInstrProfFileOverriderFuncName(), M);

     // Create variable for profile name.
     Constant *ProfileNameConst =
         ConstantDataArray::getString(M->getContext(), InstrProfileOutput, true);
     GlobalVariable *ProfileName =
         new GlobalVariable(*M, ProfileNameConst->getType(), true,
                            GlobalValue::PrivateLinkage, ProfileNameConst);

     IRB.CreateCall(SetNameF, IRB.CreatePointerCast(ProfileName, Int8PtrTy));
   }
   IRB.CreateRetVoid();

   appendToGlobalCtors(*M, F, 0);
 }
	//===-- InstrProfiling.cpp - Frontend instrumentation based profiling -----===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This pass lowers instrprof_* intrinsics emitted by a frontend for profiling.
	// It also builds the data structures and initialization code needed for
	// updating execution counts and emitting the profile at runtime.
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/ADT/Triple.h"
	#include "llvm/IR/IRBuilder.h"
	#include "llvm/IR/IntrinsicInst.h"
	#include "llvm/IR/Module.h"
	#include "llvm/ProfileData/InstrProf.h"
	#include "llvm/Transforms/Instrumentation.h"
	#include "llvm/Transforms/Utils/ModuleUtils.h"

	using namespace llvm;

	#define DEBUG_TYPE "instrprof"

	namespace {

	class InstrProfiling : public ModulePass {
	public:
	static char ID;

	InstrProfiling() : ModulePass(ID) {}

	InstrProfiling(const InstrProfOptions &Options)
	: ModulePass(ID), Options(Options) {}

	const char *getPassName() const override {
	return "Frontend instrumentation-based coverage lowering";
	}

	bool runOnModule(Module &M) override;

	void getAnalysisUsage(AnalysisUsage &AU) const override {
	AU.setPreservesCFG();
	}

	private:
	InstrProfOptions Options;
	Module *M;
	typedef struct PerFunctionProfileData {
	uint32_t NumValueSites[IPVK_Last+1];
	GlobalVariable* RegionCounters;
	GlobalVariable* DataVar;
	PerFunctionProfileData() : RegionCounters(nullptr), DataVar(nullptr) {
	memset(NumValueSites, 0, sizeof(uint32_t) * (IPVK_Last+1));
	}
	} PerFunctionProfileData;
	DenseMap<GlobalVariable *, PerFunctionProfileData> ProfileDataMap;
	std::vector<Value *> UsedVars;

	bool isMachO() const {
	return Triple(M->getTargetTriple()).isOSBinFormatMachO();
	}

	/// Get the section name for the counter variables.
	StringRef getCountersSection() const {
	return getInstrProfCountersSectionName(isMachO());
	}

	/// Get the section name for the name variables.
	StringRef getNameSection() const {
	return getInstrProfNameSectionName(isMachO());
	}

	/// Get the section name for the profile data variables.
	StringRef getDataSection() const {
	return getInstrProfDataSectionName(isMachO());
	}

	/// Get the section name for the coverage mapping data.
	StringRef getCoverageSection() const {
	return getInstrProfCoverageSectionName(isMachO());
	}

	/// Count the number of instrumented value sites for the function.
	void computeNumValueSiteCounts(InstrProfValueProfileInst *Ins);

	/// Replace instrprof_value_profile with a call to runtime library.
	void lowerValueProfileInst(InstrProfValueProfileInst *Ins);

	/// Replace instrprof_increment with an increment of the appropriate value.
	void lowerIncrement(InstrProfIncrementInst *Inc);

	/// Set up the section and uses for coverage data and its references.
	void lowerCoverageData(GlobalVariable *CoverageData);

	/// Get the region counters for an increment, creating them if necessary.
	///
	/// If the counter array doesn't yet exist, the profile data variables
	/// referring to them will also be created.
	GlobalVariable getOrCreateRegionCounters(InstrProfIncrementInst Inc);

	/// Emit runtime registration functions for each profile data variable.
	void emitRegistration();

	/// Emit the necessary plumbing to pull in the runtime initialization.
	void emitRuntimeHook();

	/// Add uses of our data variables and runtime hook.
	void emitUses();

	/// Create a static initializer for our data, on platforms that need it,
	/// and for any profile output file that was specified.
	void emitInitialization();
	};

	} // anonymous namespace

	char InstrProfiling::ID = 0;
	INITIALIZE_PASS(InstrProfiling, "instrprof",
	"Frontend instrumentation-based coverage lowering.", false,
	false)

	ModulePass *llvm::createInstrProfilingPass(const InstrProfOptions &Options) {
	return new InstrProfiling(Options);
	}

	bool InstrProfiling::runOnModule(Module &M) {
	bool MadeChange = false;

	this->M = &M;
	ProfileDataMap.clear();
	UsedVars.clear();

	// We did not know how many value sites there would be inside
	// the instrumented function. This is counting the number of instrumented
	// target value sites to enter it as field in the profile data variable.
	for (Function &F : M)
	for (BasicBlock &BB : F)
	for (auto I = BB.begin(), E = BB.end(); I != E;)
	if (auto *Ind = dyn_cast<InstrProfValueProfileInst>(I++))
	computeNumValueSiteCounts(Ind);

	for (Function &F : M)
	for (BasicBlock &BB : F)
	for (auto I = BB.begin(), E = BB.end(); I != E;) {
	auto Instr = I++;
	if (auto *Inc = dyn_cast<InstrProfIncrementInst>(Instr)) {
	lowerIncrement(Inc);
	MadeChange = true;
	} else if (auto *Ind = dyn_cast<InstrProfValueProfileInst>(Instr)) {
	lowerValueProfileInst(Ind);
	MadeChange = true;
	}
	}

	if (GlobalVariable *Coverage =
	M.getNamedGlobal(getCoverageMappingVarName())) {
	lowerCoverageData(Coverage);
	MadeChange = true;
	}

	if (!MadeChange)
	return false;

	emitRegistration();
	emitRuntimeHook();
	emitUses();
	emitInitialization();
	return true;
	}

	static Constant *getOrInsertValueProfilingCall(Module &M) {
	LLVMContext &Ctx = M.getContext();
	auto *ReturnTy = Type::getVoidTy(M.getContext());
	Type *ParamTypes[] = {
	#define VALUE_PROF_FUNC_PARAM(ParamType, ParamName, ParamLLVMType) ParamLLVMType
	#include "llvm/ProfileData/InstrProfData.inc"
	};
	auto *ValueProfilingCallTy =
	FunctionType::get(ReturnTy, makeArrayRef(ParamTypes), false);
	return M.getOrInsertFunction(getInstrProfValueProfFuncName(),
	ValueProfilingCallTy);
	}

	void InstrProfiling::computeNumValueSiteCounts(InstrProfValueProfileInst *Ind) {

	GlobalVariable *Name = Ind->getName();
	uint64_t ValueKind = Ind->getValueKind()->getZExtValue();
	uint64_t Index = Ind->getIndex()->getZExtValue();
	auto It = ProfileDataMap.find(Name);
	if (It == ProfileDataMap.end()) {
	PerFunctionProfileData PD;
	PD.NumValueSites[ValueKind] = Index + 1;
	ProfileDataMap[Name] = PD;
	} else if (It->second.NumValueSites[ValueKind] <= Index)
	It->second.NumValueSites[ValueKind] = Index + 1;
	}

	void InstrProfiling::lowerValueProfileInst(InstrProfValueProfileInst *Ind) {

	GlobalVariable *Name = Ind->getName();
	auto It = ProfileDataMap.find(Name);
	assert(It != ProfileDataMap.end() && It->second.DataVar &&
	"value profiling detected in function with no counter incerement");

	GlobalVariable *DataVar = It->second.DataVar;
	uint64_t ValueKind = Ind->getValueKind()->getZExtValue();
	uint64_t Index = Ind->getIndex()->getZExtValue();
	for (uint32_t Kind = IPVK_First; Kind < ValueKind; ++Kind)
	Index += It->second.NumValueSites[Kind];

	IRBuilder<> Builder(Ind);
	Value* Args[3] = {Ind->getTargetValue(),
	Builder.CreateBitCast(DataVar, Builder.getInt8PtrTy()),
	Builder.getInt32(Index)};
	Ind->replaceAllUsesWith(
	Builder.CreateCall(getOrInsertValueProfilingCall(*M), Args));
	Ind->eraseFromParent();
	}

	void InstrProfiling::lowerIncrement(InstrProfIncrementInst *Inc) {
	GlobalVariable *Counters = getOrCreateRegionCounters(Inc);

	IRBuilder<> Builder(Inc);
	uint64_t Index = Inc->getIndex()->getZExtValue();
	Value *Addr = Builder.CreateConstInBoundsGEP2_64(Counters, 0, Index);
	Value *Count = Builder.CreateLoad(Addr, "pgocount");
	Count = Builder.CreateAdd(Count, Builder.getInt64(1));
	Inc->replaceAllUsesWith(Builder.CreateStore(Count, Addr));
	Inc->eraseFromParent();
	}

	void InstrProfiling::lowerCoverageData(GlobalVariable *CoverageData) {
	CoverageData->setSection(getCoverageSection());
	CoverageData->setAlignment(8);

	Constant *Init = CoverageData->getInitializer();
	// We're expecting { i32, i32, i32, i32, [n x { i8*, i32, i32 }], [m x i8] }
	// for some C. If not, the frontend's given us something broken.
	assert(Init->getNumOperands() == 6 && "bad number of fields in coverage map");
	assert(isa<ConstantArray>(Init->getAggregateElement(4)) &&
	"invalid function list in coverage map");
	ConstantArray *Records = cast<ConstantArray>(Init->getAggregateElement(4));
	for (unsigned I = 0, E = Records->getNumOperands(); I < E; ++I) {
	Constant *Record = Records->getOperand(I);
	Value V = const_cast<Value >(Record->getOperand(0))->stripPointerCasts();

	assert(isa<GlobalVariable>(V) && "Missing reference to function name");
	GlobalVariable *Name = cast<GlobalVariable>(V);

	// If we have region counters for this name, we've already handled it.
	auto It = ProfileDataMap.find(Name);
	if (It != ProfileDataMap.end())
	if (It->second.RegionCounters)
	continue;

	// Move the name variable to the right section.
	Name->setSection(getNameSection());
	Name->setAlignment(1);
	}
	}

	/// Get the name of a profiling variable for a particular function.
	static std::string getVarName(InstrProfIncrementInst *Inc, StringRef Prefix) {
	StringRef NamePrefix = getInstrProfNameVarPrefix();
	StringRef Name = Inc->getName()->getName().substr(NamePrefix.size());
	return (Prefix + Name).str();
	}

	static inline bool shouldRecordFunctionAddr(Function *F) {
	// Check the linkage
	if (!F->hasLinkOnceLinkage() && !F->hasLocalLinkage() &&
	!F->hasAvailableExternallyLinkage())
	return true;
	// Check uses of this function for other than direct calls or invokes to it.
	return F->hasAddressTaken();
	}

	static inline Comdat *getOrCreateProfileComdat(Module &M,
	InstrProfIncrementInst *Inc) {
	// COFF format requires a COMDAT section to have a key symbol with the same
	// name. The linker targeting COFF also requires that the COMDAT section
	// a section is associated to must precede the associating section. For this
	// reason, we must choose the name var's name as the name of the comdat.
	StringRef ComdatPrefix = (Triple(M.getTargetTriple()).isOSBinFormatCOFF()
	? getInstrProfNameVarPrefix()
	: getInstrProfComdatPrefix());
	return M.getOrInsertComdat(StringRef(getVarName(Inc, ComdatPrefix)));
	}

	GlobalVariable *
	InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
	GlobalVariable *NamePtr = Inc->getName();
	auto It = ProfileDataMap.find(NamePtr);
	PerFunctionProfileData PD;
	if (It != ProfileDataMap.end()) {
	if (It->second.RegionCounters)
	return It->second.RegionCounters;
	PD = It->second;
	}

	// Move the name variable to the right section. Place them in a COMDAT group
	// if the associated function is a COMDAT. This will make sure that
	// only one copy of counters of the COMDAT function will be emitted after
	// linking.
	Function *Fn = Inc->getParent()->getParent();
	Comdat *ProfileVarsComdat = nullptr;
	if (Fn->hasComdat())
	ProfileVarsComdat = getOrCreateProfileComdat(*M, Inc);
	NamePtr->setSection(getNameSection());
	NamePtr->setAlignment(1);
	NamePtr->setComdat(ProfileVarsComdat);

	uint64_t NumCounters = Inc->getNumCounters()->getZExtValue();
	LLVMContext &Ctx = M->getContext();
	ArrayType *CounterTy = ArrayType::get(Type::getInt64Ty(Ctx), NumCounters);

	// Create the counters variable.
	auto *CounterPtr =
	new GlobalVariable(*M, CounterTy, false, NamePtr->getLinkage(),
	Constant::getNullValue(CounterTy),
	getVarName(Inc, getInstrProfCountersVarPrefix()));
	CounterPtr->setVisibility(NamePtr->getVisibility());
	CounterPtr->setSection(getCountersSection());
	CounterPtr->setAlignment(8);
	CounterPtr->setComdat(ProfileVarsComdat);

	// Create data variable.
	auto *Int8PtrTy = Type::getInt8PtrTy(Ctx);
	auto *Int16Ty = Type::getInt16Ty(Ctx);
	auto *Int16ArrayTy = ArrayType::get(Int16Ty, IPVK_Last+1);
	Type *DataTypes[] = {
	#define INSTR_PROF_DATA(Type, LLVMType, Name, Init) LLVMType,
	#include "llvm/ProfileData/InstrProfData.inc"
	};
	auto *DataTy = StructType::get(Ctx, makeArrayRef(DataTypes));

	Constant *FunctionAddr = shouldRecordFunctionAddr(Fn) ?
	ConstantExpr::getBitCast(Fn, Int8PtrTy) :
	ConstantPointerNull::get(Int8PtrTy);

	Constant *Int16ArrayVals[IPVK_Last+1];
	for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
	Int16ArrayVals[Kind] = ConstantInt::get(Int16Ty, PD.NumValueSites[Kind]);

	Constant *DataVals[] = {
	#define INSTR_PROF_DATA(Type, LLVMType, Name, Init) Init,
	#include "llvm/ProfileData/InstrProfData.inc"
	};
	auto Data = new GlobalVariable(M, DataTy, false, NamePtr->getLinkage(),
	ConstantStruct::get(DataTy, DataVals),
	getVarName(Inc, getInstrProfDataVarPrefix()));
	Data->setVisibility(NamePtr->getVisibility());
	Data->setSection(getDataSection());
	Data->setAlignment(INSTR_PROF_DATA_ALIGNMENT);
	Data->setComdat(ProfileVarsComdat);

	PD.RegionCounters = CounterPtr;
	PD.DataVar = Data;
	ProfileDataMap[NamePtr] = PD;

	// Mark the data variable as used so that it isn't stripped out.
	UsedVars.push_back(Data);

	return CounterPtr;
	}

	void InstrProfiling::emitRegistration() {
	// Don't do this for Darwin. compiler-rt uses linker magic.
	if (Triple(M->getTargetTriple()).isOSDarwin())
	return;

	// Use linker script magic to get data/cnts/name start/end.
	if (Triple(M->getTargetTriple()).isOSLinux() \|\|
	Triple(M->getTargetTriple()).isOSFreeBSD())
	return;

	// Construct the function.
	auto *VoidTy = Type::getVoidTy(M->getContext());
	auto *VoidPtrTy = Type::getInt8PtrTy(M->getContext());
	auto *RegisterFTy = FunctionType::get(VoidTy, false);
	auto *RegisterF = Function::Create(RegisterFTy, GlobalValue::InternalLinkage,
	getInstrProfRegFuncsName(), M);
	RegisterF->setUnnamedAddr(true);
	if (Options.NoRedZone) RegisterF->addFnAttr(Attribute::NoRedZone);

	auto *RuntimeRegisterTy = FunctionType::get(VoidTy, VoidPtrTy, false);
	auto *RuntimeRegisterF =
	Function::Create(RuntimeRegisterTy, GlobalVariable::ExternalLinkage,
	getInstrProfRegFuncName(), M);

	IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", RegisterF));
	for (Value *Data : UsedVars)
	IRB.CreateCall(RuntimeRegisterF, IRB.CreateBitCast(Data, VoidPtrTy));
	IRB.CreateRetVoid();
	}

	void InstrProfiling::emitRuntimeHook() {

	// We expect the linker to be invoked with -u<hook_var> flag for linux,
	// for which case there is no need to emit the user function.
	if (Triple(M->getTargetTriple()).isOSLinux())
	return;

	// If the module's provided its own runtime, we don't need to do anything.
	if (M->getGlobalVariable(getInstrProfRuntimeHookVarName())) return;

	// Declare an external variable that will pull in the runtime initialization.
	auto *Int32Ty = Type::getInt32Ty(M->getContext());
	auto *Var =
	new GlobalVariable(*M, Int32Ty, false, GlobalValue::ExternalLinkage,
	nullptr, getInstrProfRuntimeHookVarName());

	// Make a function that uses it.
	auto *User = Function::Create(FunctionType::get(Int32Ty, false),
	GlobalValue::LinkOnceODRLinkage,
	getInstrProfRuntimeHookVarUseFuncName(), M);
	User->addFnAttr(Attribute::NoInline);
	if (Options.NoRedZone) User->addFnAttr(Attribute::NoRedZone);
	User->setVisibility(GlobalValue::HiddenVisibility);

	IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", User));
	auto *Load = IRB.CreateLoad(Var);
	IRB.CreateRet(Load);

	// Mark the user variable as used so that it isn't stripped out.
	UsedVars.push_back(User);
	}

	void InstrProfiling::emitUses() {
	if (UsedVars.empty())
	return;

	GlobalVariable *LLVMUsed = M->getGlobalVariable("llvm.used");
	std::vector<Constant *> MergedVars;
	if (LLVMUsed) {
	// Collect the existing members of llvm.used.
	ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
	for (unsigned I = 0, E = Inits->getNumOperands(); I != E; ++I)
	MergedVars.push_back(Inits->getOperand(I));
	LLVMUsed->eraseFromParent();
	}

	Type *i8PTy = Type::getInt8PtrTy(M->getContext());
	// Add uses for our data.
	for (auto *Value : UsedVars)
	MergedVars.push_back(
	ConstantExpr::getBitCast(cast<Constant>(Value), i8PTy));

	// Recreate llvm.used.
	ArrayType *ATy = ArrayType::get(i8PTy, MergedVars.size());
	LLVMUsed =
	new GlobalVariable(*M, ATy, false, GlobalValue::AppendingLinkage,
	ConstantArray::get(ATy, MergedVars), "llvm.used");
	LLVMUsed->setSection("llvm.metadata");
	}

	void InstrProfiling::emitInitialization() {
	std::string InstrProfileOutput = Options.InstrProfileOutput;

	Constant *RegisterF = M->getFunction(getInstrProfRegFuncsName());
	if (!RegisterF && InstrProfileOutput.empty()) return;

	// Create the initialization function.
	auto *VoidTy = Type::getVoidTy(M->getContext());
	auto *F = Function::Create(FunctionType::get(VoidTy, false),
	GlobalValue::InternalLinkage,
	getInstrProfInitFuncName(), M);
	F->setUnnamedAddr(true);
	F->addFnAttr(Attribute::NoInline);
	if (Options.NoRedZone) F->addFnAttr(Attribute::NoRedZone);

	// Add the basic block and the necessary calls.
	IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", F));
	if (RegisterF)
	IRB.CreateCall(RegisterF, {});
	if (!InstrProfileOutput.empty()) {
	auto *Int8PtrTy = Type::getInt8PtrTy(M->getContext());
	auto *SetNameTy = FunctionType::get(VoidTy, Int8PtrTy, false);
	auto *SetNameF = Function::Create(SetNameTy, GlobalValue::ExternalLinkage,
	getInstrProfFileOverriderFuncName(), M);

	// Create variable for profile name.
	Constant *ProfileNameConst =
	ConstantDataArray::getString(M->getContext(), InstrProfileOutput, true);
	GlobalVariable *ProfileName =
	new GlobalVariable(*M, ProfileNameConst->getType(), true,
	GlobalValue::PrivateLinkage, ProfileNameConst);

	IRB.CreateCall(SetNameF, IRB.CreatePointerCast(ProfileName, Int8PtrTy));
	}
	IRB.CreateRetVoid();

	appendToGlobalCtors(*M, F, 0);
	}