safecode/tools/clang/lib/CodeGen/CGCUDANV.cpp - llvm-archive - Git at Google

 //===----- CGCUDANV.cpp - Interface to NVIDIA CUDA Runtime ----------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This provides a class for CUDA code generation targeting the NVIDIA CUDA
 // runtime library.
 //
 //===----------------------------------------------------------------------===//

 #include "CGCUDARuntime.h"
 #include "CodeGenFunction.h"
 #include "CodeGenModule.h"
 #include "clang/AST/Decl.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/CallSite.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DerivedTypes.h"

 using namespace clang;
 using namespace CodeGen;

 namespace {

 class CGNVCUDARuntime : public CGCUDARuntime {

 private:
   llvm::Type *IntTy, *SizeTy, *VoidTy;
   llvm::PointerType *CharPtrTy, *VoidPtrTy, *VoidPtrPtrTy;

   /// Convenience reference to LLVM Context
   llvm::LLVMContext &Context;
   /// Convenience reference to the current module
   llvm::Module &TheModule;
   /// Keeps track of kernel launch stubs emitted in this module
   llvm::SmallVector<llvm::Function *, 16> EmittedKernels;
   /// Keeps track of variables containing handles of GPU binaries. Populated by
   /// ModuleCtorFunction() and used to create corresponding cleanup calls in
   /// ModuleDtorFunction()
   llvm::SmallVector<llvm::GlobalVariable *, 16> GpuBinaryHandles;

   llvm::Constant *getSetupArgumentFn() const;
   llvm::Constant *getLaunchFn() const;

   /// Creates a function to register all kernel stubs generated in this module.
   llvm::Function *makeRegisterKernelsFn();

   /// Helper function that generates a constant string and returns a pointer to
   /// the start of the string.  The result of this function can be used anywhere
   /// where the C code specifies const char*.
   llvm::Constant *makeConstantString(const std::string &Str,
                                      const std::string &Name = "",
                                      unsigned Alignment = 0) {
     llvm::Constant *Zeros[] = {llvm::ConstantInt::get(SizeTy, 0),
                                llvm::ConstantInt::get(SizeTy, 0)};
     auto *ConstStr = CGM.GetAddrOfConstantCString(Str, Name.c_str());
     return llvm::ConstantExpr::getGetElementPtr(ConstStr->getValueType(),
                                                 ConstStr, Zeros);
  }

   void emitDeviceStubBody(CodeGenFunction &CGF, FunctionArgList &Args);

 public:
   CGNVCUDARuntime(CodeGenModule &CGM);

   void emitDeviceStub(CodeGenFunction &CGF, FunctionArgList &Args) override;
   /// Creates module constructor function
   llvm::Function *makeModuleCtorFunction() override;
   /// Creates module destructor function
   llvm::Function *makeModuleDtorFunction() override;
 };

 }

 CGNVCUDARuntime::CGNVCUDARuntime(CodeGenModule &CGM)
     : CGCUDARuntime(CGM), Context(CGM.getLLVMContext()),
       TheModule(CGM.getModule()) {
   CodeGen::CodeGenTypes &Types = CGM.getTypes();
   ASTContext &Ctx = CGM.getContext();

   IntTy = Types.ConvertType(Ctx.IntTy);
   SizeTy = Types.ConvertType(Ctx.getSizeType());
   VoidTy = llvm::Type::getVoidTy(Context);

   CharPtrTy = llvm::PointerType::getUnqual(Types.ConvertType(Ctx.CharTy));
   VoidPtrTy = cast<llvm::PointerType>(Types.ConvertType(Ctx.VoidPtrTy));
   VoidPtrPtrTy = VoidPtrTy->getPointerTo();
 }

 llvm::Constant *CGNVCUDARuntime::getSetupArgumentFn() const {
   // cudaError_t cudaSetupArgument(void *, size_t, size_t)
   std::vector<llvm::Type*> Params;
   Params.push_back(VoidPtrTy);
   Params.push_back(SizeTy);
   Params.push_back(SizeTy);
   return CGM.CreateRuntimeFunction(llvm::FunctionType::get(IntTy,
                                                            Params, false),
                                    "cudaSetupArgument");
 }

 llvm::Constant *CGNVCUDARuntime::getLaunchFn() const {
   // cudaError_t cudaLaunch(char *)
   return CGM.CreateRuntimeFunction(
       llvm::FunctionType::get(IntTy, CharPtrTy, false), "cudaLaunch");
 }

 void CGNVCUDARuntime::emitDeviceStub(CodeGenFunction &CGF,
                                      FunctionArgList &Args) {
   EmittedKernels.push_back(CGF.CurFn);
   emitDeviceStubBody(CGF, Args);
 }

 void CGNVCUDARuntime::emitDeviceStubBody(CodeGenFunction &CGF,
                                          FunctionArgList &Args) {
   // Build the argument value list and the argument stack struct type.
   SmallVector<llvm::Value *, 16> ArgValues;
   std::vector<llvm::Type *> ArgTypes;
   for (FunctionArgList::const_iterator I = Args.begin(), E = Args.end();
        I != E; ++I) {
     llvm::Value *V = CGF.GetAddrOfLocalVar(*I);
     ArgValues.push_back(V);
     assert(isa<llvm::PointerType>(V->getType()) && "Arg type not PointerType");
     ArgTypes.push_back(cast<llvm::PointerType>(V->getType())->getElementType());
   }
   llvm::StructType *ArgStackTy = llvm::StructType::get(Context, ArgTypes);

   llvm::BasicBlock *EndBlock = CGF.createBasicBlock("setup.end");

   // Emit the calls to cudaSetupArgument
   llvm::Constant *cudaSetupArgFn = getSetupArgumentFn();
   for (unsigned I = 0, E = Args.size(); I != E; ++I) {
     llvm::Value *Args[3];
     llvm::BasicBlock *NextBlock = CGF.createBasicBlock("setup.next");
     Args[0] = CGF.Builder.CreatePointerCast(ArgValues[I], VoidPtrTy);
     Args[1] = CGF.Builder.CreateIntCast(
         llvm::ConstantExpr::getSizeOf(ArgTypes[I]),
         SizeTy, false);
     Args[2] = CGF.Builder.CreateIntCast(
         llvm::ConstantExpr::getOffsetOf(ArgStackTy, I),
         SizeTy, false);
     llvm::CallSite CS = CGF.EmitRuntimeCallOrInvoke(cudaSetupArgFn, Args);
     llvm::Constant *Zero = llvm::ConstantInt::get(IntTy, 0);
     llvm::Value *CSZero = CGF.Builder.CreateICmpEQ(CS.getInstruction(), Zero);
     CGF.Builder.CreateCondBr(CSZero, NextBlock, EndBlock);
     CGF.EmitBlock(NextBlock);
   }

   // Emit the call to cudaLaunch
   llvm::Constant *cudaLaunchFn = getLaunchFn();
   llvm::Value *Arg = CGF.Builder.CreatePointerCast(CGF.CurFn, CharPtrTy);
   CGF.EmitRuntimeCallOrInvoke(cudaLaunchFn, Arg);
   CGF.EmitBranch(EndBlock);

   CGF.EmitBlock(EndBlock);
 }

 /// Creates internal function to register all kernel stubs generated in this
 /// module with the CUDA runtime.
 /// \code
 /// void __cuda_register_kernels(void** GpuBinaryHandle) {
 ///    __cudaRegisterFunction(GpuBinaryHandle,Kernel0,...);
 ///    ...
 ///    __cudaRegisterFunction(GpuBinaryHandle,KernelM,...);
 /// }
 /// \endcode
 llvm::Function *CGNVCUDARuntime::makeRegisterKernelsFn() {
   llvm::Function *RegisterKernelsFunc = llvm::Function::Create(
       llvm::FunctionType::get(VoidTy, VoidPtrPtrTy, false),
       llvm::GlobalValue::InternalLinkage, "__cuda_register_kernels", &TheModule);
   llvm::BasicBlock *EntryBB =
       llvm::BasicBlock::Create(Context, "entry", RegisterKernelsFunc);
   CGBuilderTy Builder(Context);
   Builder.SetInsertPoint(EntryBB);

   // void __cudaRegisterFunction(void **, const char *, char *, const char *,
   //                             int, uint3*, uint3*, dim3*, dim3*, int*)
   std::vector<llvm::Type *> RegisterFuncParams = {
       VoidPtrPtrTy, CharPtrTy, CharPtrTy, CharPtrTy, IntTy,
       VoidPtrTy,    VoidPtrTy, VoidPtrTy, VoidPtrTy, IntTy->getPointerTo()};
   llvm::Constant *RegisterFunc = CGM.CreateRuntimeFunction(
       llvm::FunctionType::get(IntTy, RegisterFuncParams, false),
       "__cudaRegisterFunction");

   // Extract GpuBinaryHandle passed as the first argument passed to
   // __cuda_register_kernels() and generate __cudaRegisterFunction() call for
   // each emitted kernel.
   llvm::Argument &GpuBinaryHandlePtr = *RegisterKernelsFunc->arg_begin();
   for (llvm::Function *Kernel : EmittedKernels) {
     llvm::Constant *KernelName = makeConstantString(Kernel->getName());
     llvm::Constant *NullPtr = llvm::ConstantPointerNull::get(VoidPtrTy);
     llvm::Value *args[] = {
         &GpuBinaryHandlePtr, Builder.CreateBitCast(Kernel, VoidPtrTy),
         KernelName, KernelName, llvm::ConstantInt::get(IntTy, -1), NullPtr,
         NullPtr, NullPtr, NullPtr,
         llvm::ConstantPointerNull::get(IntTy->getPointerTo())};
     Builder.CreateCall(RegisterFunc, args);
   }

   Builder.CreateRetVoid();
   return RegisterKernelsFunc;
 }

 /// Creates a global constructor function for the module:
 /// \code
 /// void __cuda_module_ctor(void*) {
 ///     Handle0 = __cudaRegisterFatBinary(GpuBinaryBlob0);
 ///     __cuda_register_kernels(Handle0);
 ///     ...
 ///     HandleN = __cudaRegisterFatBinary(GpuBinaryBlobN);
 ///     __cuda_register_kernels(HandleN);
 /// }
 /// \endcode
 llvm::Function *CGNVCUDARuntime::makeModuleCtorFunction() {
   // void __cuda_register_kernels(void* handle);
   llvm::Function *RegisterKernelsFunc = makeRegisterKernelsFn();
   // void ** __cudaRegisterFatBinary(void *);
   llvm::Constant *RegisterFatbinFunc = CGM.CreateRuntimeFunction(
       llvm::FunctionType::get(VoidPtrPtrTy, VoidPtrTy, false),
       "__cudaRegisterFatBinary");
   // struct { int magic, int version, void * gpu_binary, void * dont_care };
   llvm::StructType *FatbinWrapperTy =
       llvm::StructType::get(IntTy, IntTy, VoidPtrTy, VoidPtrTy, nullptr);

   llvm::Function *ModuleCtorFunc = llvm::Function::Create(
       llvm::FunctionType::get(VoidTy, VoidPtrTy, false),
       llvm::GlobalValue::InternalLinkage, "__cuda_module_ctor", &TheModule);
   llvm::BasicBlock *CtorEntryBB =
       llvm::BasicBlock::Create(Context, "entry", ModuleCtorFunc);
   CGBuilderTy CtorBuilder(Context);

   CtorBuilder.SetInsertPoint(CtorEntryBB);

   // For each GPU binary, register it with the CUDA runtime and store returned
   // handle in a global variable and save the handle in GpuBinaryHandles vector
   // to be cleaned up in destructor on exit. Then associate all known kernels
   // with the GPU binary handle so CUDA runtime can figure out what to call on
   // the GPU side.
   for (const std::string &GpuBinaryFileName :
        CGM.getCodeGenOpts().CudaGpuBinaryFileNames) {
     llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> GpuBinaryOrErr =
         llvm::MemoryBuffer::getFileOrSTDIN(GpuBinaryFileName);
     if (std::error_code EC = GpuBinaryOrErr.getError()) {
       CGM.getDiags().Report(diag::err_cannot_open_file) << GpuBinaryFileName
                                                         << EC.message();
       continue;
     }

     // Create initialized wrapper structure that points to the loaded GPU binary
     llvm::Constant *Values[] = {
         llvm::ConstantInt::get(IntTy, 0x466243b1), // Fatbin wrapper magic.
         llvm::ConstantInt::get(IntTy, 1),          // Fatbin version.
         makeConstantString(GpuBinaryOrErr.get()->getBuffer(), "", 16), // Data.
         llvm::ConstantPointerNull::get(VoidPtrTy)}; // Unused in fatbin v1.
     llvm::GlobalVariable *FatbinWrapper = new llvm::GlobalVariable(
         TheModule, FatbinWrapperTy, true, llvm::GlobalValue::InternalLinkage,
         llvm::ConstantStruct::get(FatbinWrapperTy, Values),
         "__cuda_fatbin_wrapper");

     // GpuBinaryHandle = __cudaRegisterFatBinary(&FatbinWrapper);
     llvm::CallInst *RegisterFatbinCall = CtorBuilder.CreateCall(
         RegisterFatbinFunc,
         CtorBuilder.CreateBitCast(FatbinWrapper, VoidPtrTy));
     llvm::GlobalVariable *GpuBinaryHandle = new llvm::GlobalVariable(
         TheModule, VoidPtrPtrTy, false, llvm::GlobalValue::InternalLinkage,
         llvm::ConstantPointerNull::get(VoidPtrPtrTy), "__cuda_gpubin_handle");
     CtorBuilder.CreateStore(RegisterFatbinCall, GpuBinaryHandle, false);

     // Call __cuda_register_kernels(GpuBinaryHandle);
     CtorBuilder.CreateCall(RegisterKernelsFunc, RegisterFatbinCall);

     // Save GpuBinaryHandle so we can unregister it in destructor.
     GpuBinaryHandles.push_back(GpuBinaryHandle);
   }

   CtorBuilder.CreateRetVoid();
   return ModuleCtorFunc;
 }

 /// Creates a global destructor function that unregisters all GPU code blobs
 /// registered by constructor.
 /// \code
 /// void __cuda_module_dtor(void*) {
 ///     __cudaUnregisterFatBinary(Handle0);
 ///     ...
 ///     __cudaUnregisterFatBinary(HandleN);
 /// }
 /// \endcode
 llvm::Function *CGNVCUDARuntime::makeModuleDtorFunction() {
   // void __cudaUnregisterFatBinary(void ** handle);
   llvm::Constant *UnregisterFatbinFunc = CGM.CreateRuntimeFunction(
       llvm::FunctionType::get(VoidTy, VoidPtrPtrTy, false),
       "__cudaUnregisterFatBinary");

   llvm::Function *ModuleDtorFunc = llvm::Function::Create(
       llvm::FunctionType::get(VoidTy, VoidPtrTy, false),
       llvm::GlobalValue::InternalLinkage, "__cuda_module_dtor", &TheModule);
   llvm::BasicBlock *DtorEntryBB =
       llvm::BasicBlock::Create(Context, "entry", ModuleDtorFunc);
   CGBuilderTy DtorBuilder(Context);
   DtorBuilder.SetInsertPoint(DtorEntryBB);

   for (llvm::GlobalVariable *GpuBinaryHandle : GpuBinaryHandles) {
     DtorBuilder.CreateCall(UnregisterFatbinFunc,
                            DtorBuilder.CreateLoad(GpuBinaryHandle, false));
   }

   DtorBuilder.CreateRetVoid();
   return ModuleDtorFunc;
 }

 CGCUDARuntime *CodeGen::CreateNVCUDARuntime(CodeGenModule &CGM) {
   return new CGNVCUDARuntime(CGM);
 }
	//===----- CGCUDANV.cpp - Interface to NVIDIA CUDA Runtime ----------------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This provides a class for CUDA code generation targeting the NVIDIA CUDA
	// runtime library.
	//
	//===----------------------------------------------------------------------===//

	#include "CGCUDARuntime.h"
	#include "CodeGenFunction.h"
	#include "CodeGenModule.h"
	#include "clang/AST/Decl.h"
	#include "llvm/IR/BasicBlock.h"
	#include "llvm/IR/CallSite.h"
	#include "llvm/IR/Constants.h"
	#include "llvm/IR/DerivedTypes.h"

	using namespace clang;
	using namespace CodeGen;

	namespace {

	class CGNVCUDARuntime : public CGCUDARuntime {

	private:
	llvm::Type IntTy, SizeTy, *VoidTy;
	llvm::PointerType CharPtrTy, VoidPtrTy, *VoidPtrPtrTy;

	/// Convenience reference to LLVM Context
	llvm::LLVMContext &Context;
	/// Convenience reference to the current module
	llvm::Module &TheModule;
	/// Keeps track of kernel launch stubs emitted in this module
	llvm::SmallVector<llvm::Function *, 16> EmittedKernels;
	/// Keeps track of variables containing handles of GPU binaries. Populated by
	/// ModuleCtorFunction() and used to create corresponding cleanup calls in
	/// ModuleDtorFunction()
	llvm::SmallVector<llvm::GlobalVariable *, 16> GpuBinaryHandles;

	llvm::Constant *getSetupArgumentFn() const;
	llvm::Constant *getLaunchFn() const;

	/// Creates a function to register all kernel stubs generated in this module.
	llvm::Function *makeRegisterKernelsFn();

	/// Helper function that generates a constant string and returns a pointer to
	/// the start of the string. The result of this function can be used anywhere
	/// where the C code specifies const char*.
	llvm::Constant *makeConstantString(const std::string &Str,
	const std::string &Name = "",
	unsigned Alignment = 0) {
	llvm::Constant *Zeros[] = {llvm::ConstantInt::get(SizeTy, 0),
	llvm::ConstantInt::get(SizeTy, 0)};
	auto *ConstStr = CGM.GetAddrOfConstantCString(Str, Name.c_str());
	return llvm::ConstantExpr::getGetElementPtr(ConstStr->getValueType(),
	ConstStr, Zeros);
	}

	void emitDeviceStubBody(CodeGenFunction &CGF, FunctionArgList &Args);

	public:
	CGNVCUDARuntime(CodeGenModule &CGM);

	void emitDeviceStub(CodeGenFunction &CGF, FunctionArgList &Args) override;
	/// Creates module constructor function
	llvm::Function *makeModuleCtorFunction() override;
	/// Creates module destructor function
	llvm::Function *makeModuleDtorFunction() override;
	};

	}

	CGNVCUDARuntime::CGNVCUDARuntime(CodeGenModule &CGM)
	: CGCUDARuntime(CGM), Context(CGM.getLLVMContext()),
	TheModule(CGM.getModule()) {
	CodeGen::CodeGenTypes &Types = CGM.getTypes();
	ASTContext &Ctx = CGM.getContext();

	IntTy = Types.ConvertType(Ctx.IntTy);
	SizeTy = Types.ConvertType(Ctx.getSizeType());
	VoidTy = llvm::Type::getVoidTy(Context);

	CharPtrTy = llvm::PointerType::getUnqual(Types.ConvertType(Ctx.CharTy));
	VoidPtrTy = cast<llvm::PointerType>(Types.ConvertType(Ctx.VoidPtrTy));
	VoidPtrPtrTy = VoidPtrTy->getPointerTo();
	}

	llvm::Constant *CGNVCUDARuntime::getSetupArgumentFn() const {
	// cudaError_t cudaSetupArgument(void *, size_t, size_t)
	std::vector<llvm::Type*> Params;
	Params.push_back(VoidPtrTy);
	Params.push_back(SizeTy);
	Params.push_back(SizeTy);
	return CGM.CreateRuntimeFunction(llvm::FunctionType::get(IntTy,
	Params, false),
	"cudaSetupArgument");
	}

	llvm::Constant *CGNVCUDARuntime::getLaunchFn() const {
	// cudaError_t cudaLaunch(char *)
	return CGM.CreateRuntimeFunction(
	llvm::FunctionType::get(IntTy, CharPtrTy, false), "cudaLaunch");
	}

	void CGNVCUDARuntime::emitDeviceStub(CodeGenFunction &CGF,
	FunctionArgList &Args) {
	EmittedKernels.push_back(CGF.CurFn);
	emitDeviceStubBody(CGF, Args);
	}

	void CGNVCUDARuntime::emitDeviceStubBody(CodeGenFunction &CGF,
	FunctionArgList &Args) {
	// Build the argument value list and the argument stack struct type.
	SmallVector<llvm::Value *, 16> ArgValues;
	std::vector<llvm::Type *> ArgTypes;
	for (FunctionArgList::const_iterator I = Args.begin(), E = Args.end();
	I != E; ++I) {
	llvm::Value V = CGF.GetAddrOfLocalVar(I);
	ArgValues.push_back(V);
	assert(isa<llvm::PointerType>(V->getType()) && "Arg type not PointerType");
	ArgTypes.push_back(cast<llvm::PointerType>(V->getType())->getElementType());
	}
	llvm::StructType *ArgStackTy = llvm::StructType::get(Context, ArgTypes);

	llvm::BasicBlock *EndBlock = CGF.createBasicBlock("setup.end");

	// Emit the calls to cudaSetupArgument
	llvm::Constant *cudaSetupArgFn = getSetupArgumentFn();
	for (unsigned I = 0, E = Args.size(); I != E; ++I) {
	llvm::Value *Args[3];
	llvm::BasicBlock *NextBlock = CGF.createBasicBlock("setup.next");
	Args[0] = CGF.Builder.CreatePointerCast(ArgValues[I], VoidPtrTy);
	Args[1] = CGF.Builder.CreateIntCast(
	llvm::ConstantExpr::getSizeOf(ArgTypes[I]),
	SizeTy, false);
	Args[2] = CGF.Builder.CreateIntCast(
	llvm::ConstantExpr::getOffsetOf(ArgStackTy, I),
	SizeTy, false);
	llvm::CallSite CS = CGF.EmitRuntimeCallOrInvoke(cudaSetupArgFn, Args);
	llvm::Constant *Zero = llvm::ConstantInt::get(IntTy, 0);
	llvm::Value *CSZero = CGF.Builder.CreateICmpEQ(CS.getInstruction(), Zero);
	CGF.Builder.CreateCondBr(CSZero, NextBlock, EndBlock);
	CGF.EmitBlock(NextBlock);
	}

	// Emit the call to cudaLaunch
	llvm::Constant *cudaLaunchFn = getLaunchFn();
	llvm::Value *Arg = CGF.Builder.CreatePointerCast(CGF.CurFn, CharPtrTy);
	CGF.EmitRuntimeCallOrInvoke(cudaLaunchFn, Arg);
	CGF.EmitBranch(EndBlock);

	CGF.EmitBlock(EndBlock);
	}

	/// Creates internal function to register all kernel stubs generated in this
	/// module with the CUDA runtime.
	/// \code
	/// void __cuda_register_kernels(void** GpuBinaryHandle) {
	/// __cudaRegisterFunction(GpuBinaryHandle,Kernel0,...);
	/// ...
	/// __cudaRegisterFunction(GpuBinaryHandle,KernelM,...);
	/// }
	/// \endcode
	llvm::Function *CGNVCUDARuntime::makeRegisterKernelsFn() {
	llvm::Function *RegisterKernelsFunc = llvm::Function::Create(
	llvm::FunctionType::get(VoidTy, VoidPtrPtrTy, false),
	llvm::GlobalValue::InternalLinkage, "__cuda_register_kernels", &TheModule);
	llvm::BasicBlock *EntryBB =
	llvm::BasicBlock::Create(Context, "entry", RegisterKernelsFunc);
	CGBuilderTy Builder(Context);
	Builder.SetInsertPoint(EntryBB);

	// void __cudaRegisterFunction(void *, const char , char , const char ,
	// int, uint3, uint3, dim3, dim3, int*)
	std::vector<llvm::Type *> RegisterFuncParams = {
	VoidPtrPtrTy, CharPtrTy, CharPtrTy, CharPtrTy, IntTy,
	VoidPtrTy, VoidPtrTy, VoidPtrTy, VoidPtrTy, IntTy->getPointerTo()};
	llvm::Constant *RegisterFunc = CGM.CreateRuntimeFunction(
	llvm::FunctionType::get(IntTy, RegisterFuncParams, false),
	"__cudaRegisterFunction");

	// Extract GpuBinaryHandle passed as the first argument passed to
	// __cuda_register_kernels() and generate __cudaRegisterFunction() call for
	// each emitted kernel.
	llvm::Argument &GpuBinaryHandlePtr = *RegisterKernelsFunc->arg_begin();
	for (llvm::Function *Kernel : EmittedKernels) {
	llvm::Constant *KernelName = makeConstantString(Kernel->getName());
	llvm::Constant *NullPtr = llvm::ConstantPointerNull::get(VoidPtrTy);
	llvm::Value *args[] = {
	&GpuBinaryHandlePtr, Builder.CreateBitCast(Kernel, VoidPtrTy),
	KernelName, KernelName, llvm::ConstantInt::get(IntTy, -1), NullPtr,
	NullPtr, NullPtr, NullPtr,
	llvm::ConstantPointerNull::get(IntTy->getPointerTo())};
	Builder.CreateCall(RegisterFunc, args);
	}

	Builder.CreateRetVoid();
	return RegisterKernelsFunc;
	}

	/// Creates a global constructor function for the module:
	/// \code
	/// void __cuda_module_ctor(void*) {
	/// Handle0 = __cudaRegisterFatBinary(GpuBinaryBlob0);
	/// __cuda_register_kernels(Handle0);
	/// ...
	/// HandleN = __cudaRegisterFatBinary(GpuBinaryBlobN);
	/// __cuda_register_kernels(HandleN);
	/// }
	/// \endcode
	llvm::Function *CGNVCUDARuntime::makeModuleCtorFunction() {
	// void __cuda_register_kernels(void* handle);
	llvm::Function *RegisterKernelsFunc = makeRegisterKernelsFn();
	// void ** __cudaRegisterFatBinary(void *);
	llvm::Constant *RegisterFatbinFunc = CGM.CreateRuntimeFunction(
	llvm::FunctionType::get(VoidPtrPtrTy, VoidPtrTy, false),
	"__cudaRegisterFatBinary");
	// struct { int magic, int version, void * gpu_binary, void * dont_care };
	llvm::StructType *FatbinWrapperTy =
	llvm::StructType::get(IntTy, IntTy, VoidPtrTy, VoidPtrTy, nullptr);

	llvm::Function *ModuleCtorFunc = llvm::Function::Create(
	llvm::FunctionType::get(VoidTy, VoidPtrTy, false),
	llvm::GlobalValue::InternalLinkage, "__cuda_module_ctor", &TheModule);
	llvm::BasicBlock *CtorEntryBB =
	llvm::BasicBlock::Create(Context, "entry", ModuleCtorFunc);
	CGBuilderTy CtorBuilder(Context);

	CtorBuilder.SetInsertPoint(CtorEntryBB);

	// For each GPU binary, register it with the CUDA runtime and store returned
	// handle in a global variable and save the handle in GpuBinaryHandles vector
	// to be cleaned up in destructor on exit. Then associate all known kernels
	// with the GPU binary handle so CUDA runtime can figure out what to call on
	// the GPU side.
	for (const std::string &GpuBinaryFileName :
	CGM.getCodeGenOpts().CudaGpuBinaryFileNames) {
	llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> GpuBinaryOrErr =
	llvm::MemoryBuffer::getFileOrSTDIN(GpuBinaryFileName);
	if (std::error_code EC = GpuBinaryOrErr.getError()) {
	CGM.getDiags().Report(diag::err_cannot_open_file) << GpuBinaryFileName
	<< EC.message();
	continue;
	}

	// Create initialized wrapper structure that points to the loaded GPU binary
	llvm::Constant *Values[] = {
	llvm::ConstantInt::get(IntTy, 0x466243b1), // Fatbin wrapper magic.
	llvm::ConstantInt::get(IntTy, 1), // Fatbin version.
	makeConstantString(GpuBinaryOrErr.get()->getBuffer(), "", 16), // Data.
	llvm::ConstantPointerNull::get(VoidPtrTy)}; // Unused in fatbin v1.
	llvm::GlobalVariable *FatbinWrapper = new llvm::GlobalVariable(
	TheModule, FatbinWrapperTy, true, llvm::GlobalValue::InternalLinkage,
	llvm::ConstantStruct::get(FatbinWrapperTy, Values),
	"__cuda_fatbin_wrapper");

	// GpuBinaryHandle = __cudaRegisterFatBinary(&FatbinWrapper);
	llvm::CallInst *RegisterFatbinCall = CtorBuilder.CreateCall(
	RegisterFatbinFunc,
	CtorBuilder.CreateBitCast(FatbinWrapper, VoidPtrTy));
	llvm::GlobalVariable *GpuBinaryHandle = new llvm::GlobalVariable(
	TheModule, VoidPtrPtrTy, false, llvm::GlobalValue::InternalLinkage,
	llvm::ConstantPointerNull::get(VoidPtrPtrTy), "__cuda_gpubin_handle");
	CtorBuilder.CreateStore(RegisterFatbinCall, GpuBinaryHandle, false);

	// Call __cuda_register_kernels(GpuBinaryHandle);
	CtorBuilder.CreateCall(RegisterKernelsFunc, RegisterFatbinCall);

	// Save GpuBinaryHandle so we can unregister it in destructor.
	GpuBinaryHandles.push_back(GpuBinaryHandle);
	}

	CtorBuilder.CreateRetVoid();
	return ModuleCtorFunc;
	}

	/// Creates a global destructor function that unregisters all GPU code blobs
	/// registered by constructor.
	/// \code
	/// void __cuda_module_dtor(void*) {
	/// __cudaUnregisterFatBinary(Handle0);
	/// ...
	/// __cudaUnregisterFatBinary(HandleN);
	/// }
	/// \endcode
	llvm::Function *CGNVCUDARuntime::makeModuleDtorFunction() {
	// void __cudaUnregisterFatBinary(void ** handle);
	llvm::Constant *UnregisterFatbinFunc = CGM.CreateRuntimeFunction(
	llvm::FunctionType::get(VoidTy, VoidPtrPtrTy, false),
	"__cudaUnregisterFatBinary");

	llvm::Function *ModuleDtorFunc = llvm::Function::Create(
	llvm::FunctionType::get(VoidTy, VoidPtrTy, false),
	llvm::GlobalValue::InternalLinkage, "__cuda_module_dtor", &TheModule);
	llvm::BasicBlock *DtorEntryBB =
	llvm::BasicBlock::Create(Context, "entry", ModuleDtorFunc);
	CGBuilderTy DtorBuilder(Context);
	DtorBuilder.SetInsertPoint(DtorEntryBB);

	for (llvm::GlobalVariable *GpuBinaryHandle : GpuBinaryHandles) {
	DtorBuilder.CreateCall(UnregisterFatbinFunc,
	DtorBuilder.CreateLoad(GpuBinaryHandle, false));
	}

	DtorBuilder.CreateRetVoid();
	return ModuleDtorFunc;
	}

	CGCUDARuntime *CodeGen::CreateNVCUDARuntime(CodeGenModule &CGM) {
	return new CGNVCUDARuntime(CGM);
	}