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llvm-project/clang/lib/CodeGen/CGCUDANV.cpp

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//===----- 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 "clang/CodeGen/ConstantInitBuilder.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/Support/Format.h"
using namespace clang;
using namespace CodeGen;
namespace {
constexpr unsigned CudaFatMagic = 0x466243b1;
constexpr unsigned HIPFatMagic = 0x48495046; // "HIPF"
class CGNVCUDARuntime : public CGCUDARuntime {
private:
llvm::IntegerType *IntTy, *SizeTy;
llvm::Type *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;
llvm::SmallVector<std::pair<llvm::GlobalVariable *, unsigned>, 16> DeviceVars;
/// Keeps track of variable containing handle of GPU binary. Populated by
/// ModuleCtorFunction() and used to create corresponding cleanup calls in
/// ModuleDtorFunction()
llvm::GlobalVariable *GpuBinaryHandle = nullptr;
/// Whether we generate relocatable device code.
bool RelocatableDeviceCode;
llvm::Constant *getSetupArgumentFn() const;
llvm::Constant *getLaunchFn() const;
llvm::FunctionType *getRegisterGlobalsFnTy() const;
llvm::FunctionType *getCallbackFnTy() const;
llvm::FunctionType *getRegisterLinkedBinaryFnTy() const;
std::string addPrefixToName(StringRef FuncName) const;
std::string addUnderscoredPrefixToName(StringRef FuncName) const;
/// Creates a function to register all kernel stubs generated in this module.
llvm::Function *makeRegisterGlobalsFn();
/// 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 = "",
const std::string &SectionName = "",
unsigned Alignment = 0) {
llvm::Constant *Zeros[] = {llvm::ConstantInt::get(SizeTy, 0),
llvm::ConstantInt::get(SizeTy, 0)};
auto ConstStr = CGM.GetAddrOfConstantCString(Str, Name.c_str());
llvm::GlobalVariable *GV =
cast<llvm::GlobalVariable>(ConstStr.getPointer());
if (!SectionName.empty()) {
GV->setSection(SectionName);
// Mark the address as used which make sure that this section isn't
// merged and we will really have it in the object file.
GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::None);
}
if (Alignment)
GV->setAlignment(Alignment);
return llvm::ConstantExpr::getGetElementPtr(ConstStr.getElementType(),
ConstStr.getPointer(), Zeros);
}
/// Helper function that generates an empty dummy function returning void.
llvm::Function *makeDummyFunction(llvm::FunctionType *FnTy) {
assert(FnTy->getReturnType()->isVoidTy() &&
"Can only generate dummy functions returning void!");
llvm::Function *DummyFunc = llvm::Function::Create(
FnTy, llvm::GlobalValue::InternalLinkage, "dummy", &TheModule);
llvm::BasicBlock *DummyBlock =
llvm::BasicBlock::Create(Context, "", DummyFunc);
CGBuilderTy FuncBuilder(CGM, Context);
FuncBuilder.SetInsertPoint(DummyBlock);
FuncBuilder.CreateRetVoid();
return DummyFunc;
}
void emitDeviceStubBody(CodeGenFunction &CGF, FunctionArgList &Args);
public:
CGNVCUDARuntime(CodeGenModule &CGM);
void emitDeviceStub(CodeGenFunction &CGF, FunctionArgList &Args) override;
void registerDeviceVar(llvm::GlobalVariable &Var, unsigned Flags) override {
DeviceVars.push_back(std::make_pair(&Var, Flags));
}
/// Creates module constructor function
llvm::Function *makeModuleCtorFunction() override;
/// Creates module destructor function
llvm::Function *makeModuleDtorFunction() override;
};
}
std::string CGNVCUDARuntime::addPrefixToName(StringRef FuncName) const {
if (CGM.getLangOpts().HIP)
return ((Twine("hip") + Twine(FuncName)).str());
return ((Twine("cuda") + Twine(FuncName)).str());
}
std::string
CGNVCUDARuntime::addUnderscoredPrefixToName(StringRef FuncName) const {
if (CGM.getLangOpts().HIP)
return ((Twine("__hip") + Twine(FuncName)).str());
return ((Twine("__cuda") + Twine(FuncName)).str());
}
CGNVCUDARuntime::CGNVCUDARuntime(CodeGenModule &CGM)
: CGCUDARuntime(CGM), Context(CGM.getLLVMContext()),
TheModule(CGM.getModule()),
RelocatableDeviceCode(CGM.getLangOpts().GPURelocatableDeviceCode) {
CodeGen::CodeGenTypes &Types = CGM.getTypes();
ASTContext &Ctx = CGM.getContext();
IntTy = CGM.IntTy;
SizeTy = CGM.SizeTy;
VoidTy = CGM.VoidTy;
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)
llvm::Type *Params[] = {VoidPtrTy, SizeTy, SizeTy};
return CGM.CreateRuntimeFunction(
llvm::FunctionType::get(IntTy, Params, false),
addPrefixToName("SetupArgument"));
}
llvm::Constant *CGNVCUDARuntime::getLaunchFn() const {
if (CGM.getLangOpts().HIP) {
// hipError_t hipLaunchByPtr(char *);
return CGM.CreateRuntimeFunction(
llvm::FunctionType::get(IntTy, CharPtrTy, false), "hipLaunchByPtr");
} else {
// cudaError_t cudaLaunch(char *);
return CGM.CreateRuntimeFunction(
llvm::FunctionType::get(IntTy, CharPtrTy, false), "cudaLaunch");
}
}
llvm::FunctionType *CGNVCUDARuntime::getRegisterGlobalsFnTy() const {
return llvm::FunctionType::get(VoidTy, VoidPtrPtrTy, false);
}
llvm::FunctionType *CGNVCUDARuntime::getCallbackFnTy() const {
return llvm::FunctionType::get(VoidTy, VoidPtrTy, false);
}
llvm::FunctionType *CGNVCUDARuntime::getRegisterLinkedBinaryFnTy() const {
auto CallbackFnTy = getCallbackFnTy();
auto RegisterGlobalsFnTy = getRegisterGlobalsFnTy();
llvm::Type *Params[] = {RegisterGlobalsFnTy->getPointerTo(), VoidPtrTy,
VoidPtrTy, CallbackFnTy->getPointerTo()};
return llvm::FunctionType::get(VoidTy, Params, false);
}
void CGNVCUDARuntime::emitDeviceStub(CodeGenFunction &CGF,
FunctionArgList &Args) {
EmittedKernels.push_back(CGF.CurFn);
emitDeviceStubBody(CGF, Args);
}
void CGNVCUDARuntime::emitDeviceStubBody(CodeGenFunction &CGF,
FunctionArgList &Args) {
// Emit a call to cudaSetupArgument for each arg in Args.
llvm::Constant *cudaSetupArgFn = getSetupArgumentFn();
llvm::BasicBlock *EndBlock = CGF.createBasicBlock("setup.end");
CharUnits Offset = CharUnits::Zero();
for (const VarDecl *A : Args) {
CharUnits TyWidth, TyAlign;
std::tie(TyWidth, TyAlign) =
CGM.getContext().getTypeInfoInChars(A->getType());
Offset = Offset.alignTo(TyAlign);
llvm::Value *Args[] = {
CGF.Builder.CreatePointerCast(CGF.GetAddrOfLocalVar(A).getPointer(),
VoidPtrTy),
llvm::ConstantInt::get(SizeTy, TyWidth.getQuantity()),
llvm::ConstantInt::get(SizeTy, Offset.getQuantity()),
};
llvm::CallSite CS = CGF.EmitRuntimeCallOrInvoke(cudaSetupArgFn, Args);
llvm::Constant *Zero = llvm::ConstantInt::get(IntTy, 0);
llvm::Value *CSZero = CGF.Builder.CreateICmpEQ(CS.getInstruction(), Zero);
llvm::BasicBlock *NextBlock = CGF.createBasicBlock("setup.next");
CGF.Builder.CreateCondBr(CSZero, NextBlock, EndBlock);
CGF.EmitBlock(NextBlock);
Offset += TyWidth;
}
// 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 a function that sets up state on the host side for CUDA objects that
/// have a presence on both the host and device sides. Specifically, registers
/// the host side of kernel functions and device global variables with the CUDA
/// runtime.
/// \code
/// void __cuda_register_globals(void** GpuBinaryHandle) {
/// __cudaRegisterFunction(GpuBinaryHandle,Kernel0,...);
/// ...
/// __cudaRegisterFunction(GpuBinaryHandle,KernelM,...);
/// __cudaRegisterVar(GpuBinaryHandle, GlobalVar0, ...);
/// ...
/// __cudaRegisterVar(GpuBinaryHandle, GlobalVarN, ...);
/// }
/// \endcode
llvm::Function *CGNVCUDARuntime::makeRegisterGlobalsFn() {
// No need to register anything
if (EmittedKernels.empty() && DeviceVars.empty())
return nullptr;
llvm::Function *RegisterKernelsFunc = llvm::Function::Create(
getRegisterGlobalsFnTy(), llvm::GlobalValue::InternalLinkage,
addUnderscoredPrefixToName("_register_globals"), &TheModule);
llvm::BasicBlock *EntryBB =
llvm::BasicBlock::Create(Context, "entry", RegisterKernelsFunc);
CGBuilderTy Builder(CGM, Context);
Builder.SetInsertPoint(EntryBB);
// void __cudaRegisterFunction(void **, const char *, char *, const char *,
// int, uint3*, uint3*, dim3*, dim3*, int*)
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),
addUnderscoredPrefixToName("RegisterFunction"));
// Extract GpuBinaryHandle passed as the first argument passed to
// __cuda_register_globals() 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);
}
// void __cudaRegisterVar(void **, char *, char *, const char *,
// int, int, int, int)
llvm::Type *RegisterVarParams[] = {VoidPtrPtrTy, CharPtrTy, CharPtrTy,
CharPtrTy, IntTy, IntTy,
IntTy, IntTy};
llvm::Constant *RegisterVar = CGM.CreateRuntimeFunction(
llvm::FunctionType::get(IntTy, RegisterVarParams, false),
addUnderscoredPrefixToName("RegisterVar"));
for (auto &Pair : DeviceVars) {
llvm::GlobalVariable *Var = Pair.first;
unsigned Flags = Pair.second;
llvm::Constant *VarName = makeConstantString(Var->getName());
uint64_t VarSize =
CGM.getDataLayout().getTypeAllocSize(Var->getValueType());
llvm::Value *Args[] = {
&GpuBinaryHandlePtr,
Builder.CreateBitCast(Var, VoidPtrTy),
VarName,
VarName,
llvm::ConstantInt::get(IntTy, (Flags & ExternDeviceVar) ? 1 : 0),
llvm::ConstantInt::get(IntTy, VarSize),
llvm::ConstantInt::get(IntTy, (Flags & ConstantDeviceVar) ? 1 : 0),
llvm::ConstantInt::get(IntTy, 0)};
Builder.CreateCall(RegisterVar, Args);
}
Builder.CreateRetVoid();
return RegisterKernelsFunc;
}
/// Creates a global constructor function for the module:
///
/// For CUDA:
/// \code
/// void __cuda_module_ctor(void*) {
/// Handle = __cudaRegisterFatBinary(GpuBinaryBlob);
/// __cuda_register_globals(Handle);
/// }
/// \endcode
///
/// For HIP:
/// \code
/// void __hip_module_ctor(void*) {
/// if (__hip_gpubin_handle == 0) {
/// __hip_gpubin_handle = __hipRegisterFatBinary(GpuBinaryBlob);
/// __hip_register_globals(__hip_gpubin_handle);
/// }
/// }
/// \endcode
llvm::Function *CGNVCUDARuntime::makeModuleCtorFunction() {
bool IsHIP = CGM.getLangOpts().HIP;
// No need to generate ctors/dtors if there is no GPU binary.
StringRef CudaGpuBinaryFileName = CGM.getCodeGenOpts().CudaGpuBinaryFileName;
if (CudaGpuBinaryFileName.empty() && !IsHIP)
return nullptr;
// void __{cuda|hip}_register_globals(void* handle);
llvm::Function *RegisterGlobalsFunc = makeRegisterGlobalsFn();
// We always need a function to pass in as callback. Create a dummy
// implementation if we don't need to register anything.
if (RelocatableDeviceCode && !RegisterGlobalsFunc)
RegisterGlobalsFunc = makeDummyFunction(getRegisterGlobalsFnTy());
// void ** __{cuda|hip}RegisterFatBinary(void *);
llvm::Constant *RegisterFatbinFunc = CGM.CreateRuntimeFunction(
llvm::FunctionType::get(VoidPtrPtrTy, VoidPtrTy, false),
addUnderscoredPrefixToName("RegisterFatBinary"));
// struct { int magic, int version, void * gpu_binary, void * dont_care };
llvm::StructType *FatbinWrapperTy =
llvm::StructType::get(IntTy, IntTy, VoidPtrTy, VoidPtrTy);
// Register GPU binary with the CUDA runtime, store returned handle in a
// global variable and save a reference in GpuBinaryHandle 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.
std::unique_ptr<llvm::MemoryBuffer> CudaGpuBinary = nullptr;
if (!CudaGpuBinaryFileName.empty()) {
llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> CudaGpuBinaryOrErr =
llvm::MemoryBuffer::getFileOrSTDIN(CudaGpuBinaryFileName);
if (std::error_code EC = CudaGpuBinaryOrErr.getError()) {
CGM.getDiags().Report(diag::err_cannot_open_file)
<< CudaGpuBinaryFileName << EC.message();
return nullptr;
}
CudaGpuBinary = std::move(CudaGpuBinaryOrErr.get());
}
llvm::Function *ModuleCtorFunc = llvm::Function::Create(
llvm::FunctionType::get(VoidTy, VoidPtrTy, false),
llvm::GlobalValue::InternalLinkage,
addUnderscoredPrefixToName("_module_ctor"), &TheModule);
llvm::BasicBlock *CtorEntryBB =
llvm::BasicBlock::Create(Context, "entry", ModuleCtorFunc);
CGBuilderTy CtorBuilder(CGM, Context);
CtorBuilder.SetInsertPoint(CtorEntryBB);
const char *FatbinConstantName;
const char *FatbinSectionName;
const char *ModuleIDSectionName;
StringRef ModuleIDPrefix;
llvm::Constant *FatBinStr;
unsigned FatMagic;
if (IsHIP) {
FatbinConstantName = ".hip_fatbin";
FatbinSectionName = ".hipFatBinSegment";
ModuleIDSectionName = "__hip_module_id";
ModuleIDPrefix = "__hip_";
if (CudaGpuBinary) {
// If fatbin is available from early finalization, create a string
// literal containing the fat binary loaded from the given file.
FatBinStr = makeConstantString(CudaGpuBinary->getBuffer(), "",
FatbinConstantName, 8);
} else {
// If fatbin is not available, create an external symbol
// __hip_fatbin in section .hip_fatbin. The external symbol is supposed
// to contain the fat binary but will be populated somewhere else,
// e.g. by lld through link script.
FatBinStr = new llvm::GlobalVariable(
CGM.getModule(), CGM.Int8Ty,
/*isConstant=*/true, llvm::GlobalValue::ExternalLinkage, nullptr,
"__hip_fatbin", nullptr,
llvm::GlobalVariable::NotThreadLocal);
cast<llvm::GlobalVariable>(FatBinStr)->setSection(FatbinConstantName);
}
FatMagic = HIPFatMagic;
} else {
if (RelocatableDeviceCode)
FatbinConstantName = CGM.getTriple().isMacOSX()
? "__NV_CUDA,__nv_relfatbin"
: "__nv_relfatbin";
else
FatbinConstantName =
CGM.getTriple().isMacOSX() ? "__NV_CUDA,__nv_fatbin" : ".nv_fatbin";
// NVIDIA's cuobjdump looks for fatbins in this section.
FatbinSectionName =
CGM.getTriple().isMacOSX() ? "__NV_CUDA,__fatbin" : ".nvFatBinSegment";
ModuleIDSectionName = CGM.getTriple().isMacOSX()
? "__NV_CUDA,__nv_module_id"
: "__nv_module_id";
ModuleIDPrefix = "__nv_";
// For CUDA, create a string literal containing the fat binary loaded from
// the given file.
FatBinStr = makeConstantString(CudaGpuBinary->getBuffer(), "",
FatbinConstantName, 8);
FatMagic = CudaFatMagic;
}
// Create initialized wrapper structure that points to the loaded GPU binary
ConstantInitBuilder Builder(CGM);
auto Values = Builder.beginStruct(FatbinWrapperTy);
// Fatbin wrapper magic.
Values.addInt(IntTy, FatMagic);
// Fatbin version.
Values.addInt(IntTy, 1);
// Data.
Values.add(FatBinStr);
// Unused in fatbin v1.
Values.add(llvm::ConstantPointerNull::get(VoidPtrTy));
llvm::GlobalVariable *FatbinWrapper = Values.finishAndCreateGlobal(
addUnderscoredPrefixToName("_fatbin_wrapper"), CGM.getPointerAlign(),
/*constant*/ true);
FatbinWrapper->setSection(FatbinSectionName);
// There is only one HIP fat binary per linked module, however there are
// multiple constructor functions. Make sure the fat binary is registered
// only once. The constructor functions are executed by the dynamic loader
// before the program gains control. The dynamic loader cannot execute the
// constructor functions concurrently since doing that would not guarantee
// thread safety of the loaded program. Therefore we can assume sequential
// execution of constructor functions here.
if (IsHIP) {
auto Linkage = CudaGpuBinary ? llvm::GlobalValue::InternalLinkage :
llvm::GlobalValue::LinkOnceAnyLinkage;
llvm::BasicBlock *IfBlock =
llvm::BasicBlock::Create(Context, "if", ModuleCtorFunc);
llvm::BasicBlock *ExitBlock =
llvm::BasicBlock::Create(Context, "exit", ModuleCtorFunc);
// The name, size, and initialization pattern of this variable is part
// of HIP ABI.
GpuBinaryHandle = new llvm::GlobalVariable(
TheModule, VoidPtrPtrTy, /*isConstant=*/false,
Linkage,
/*Initializer=*/llvm::ConstantPointerNull::get(VoidPtrPtrTy),
"__hip_gpubin_handle");
GpuBinaryHandle->setAlignment(CGM.getPointerAlign().getQuantity());
// Prevent the weak symbol in different shared libraries being merged.
if (Linkage != llvm::GlobalValue::InternalLinkage)
GpuBinaryHandle->setVisibility(llvm::GlobalValue::HiddenVisibility);
Address GpuBinaryAddr(
GpuBinaryHandle,
CharUnits::fromQuantity(GpuBinaryHandle->getAlignment()));
{
auto HandleValue = CtorBuilder.CreateLoad(GpuBinaryAddr);
llvm::Constant *Zero =
llvm::Constant::getNullValue(HandleValue->getType());
llvm::Value *EQZero = CtorBuilder.CreateICmpEQ(HandleValue, Zero);
CtorBuilder.CreateCondBr(EQZero, IfBlock, ExitBlock);
}
{
CtorBuilder.SetInsertPoint(IfBlock);
// GpuBinaryHandle = __hipRegisterFatBinary(&FatbinWrapper);
llvm::CallInst *RegisterFatbinCall = CtorBuilder.CreateCall(
RegisterFatbinFunc,
CtorBuilder.CreateBitCast(FatbinWrapper, VoidPtrTy));
CtorBuilder.CreateStore(RegisterFatbinCall, GpuBinaryAddr);
CtorBuilder.CreateBr(ExitBlock);
}
{
CtorBuilder.SetInsertPoint(ExitBlock);
// Call __hip_register_globals(GpuBinaryHandle);
if (RegisterGlobalsFunc) {
auto HandleValue = CtorBuilder.CreateLoad(GpuBinaryAddr);
CtorBuilder.CreateCall(RegisterGlobalsFunc, HandleValue);
}
}
} else if (!RelocatableDeviceCode) {
// Register binary with CUDA runtime. This is substantially different in
// default mode vs. separate compilation!
// GpuBinaryHandle = __cudaRegisterFatBinary(&FatbinWrapper);
llvm::CallInst *RegisterFatbinCall = CtorBuilder.CreateCall(
RegisterFatbinFunc,
CtorBuilder.CreateBitCast(FatbinWrapper, VoidPtrTy));
GpuBinaryHandle = new llvm::GlobalVariable(
TheModule, VoidPtrPtrTy, false, llvm::GlobalValue::InternalLinkage,
llvm::ConstantPointerNull::get(VoidPtrPtrTy), "__cuda_gpubin_handle");
GpuBinaryHandle->setAlignment(CGM.getPointerAlign().getQuantity());
CtorBuilder.CreateAlignedStore(RegisterFatbinCall, GpuBinaryHandle,
CGM.getPointerAlign());
// Call __cuda_register_globals(GpuBinaryHandle);
if (RegisterGlobalsFunc)
CtorBuilder.CreateCall(RegisterGlobalsFunc, RegisterFatbinCall);
} else {
// Generate a unique module ID.
SmallString<64> ModuleID;
llvm::raw_svector_ostream OS(ModuleID);
OS << ModuleIDPrefix << llvm::format("%x", FatbinWrapper->getGUID());
llvm::Constant *ModuleIDConstant =
makeConstantString(ModuleID.str(), "", ModuleIDSectionName, 32);
// Create an alias for the FatbinWrapper that nvcc will look for.
llvm::GlobalAlias::create(llvm::GlobalValue::ExternalLinkage,
Twine("__fatbinwrap") + ModuleID, FatbinWrapper);
// void __cudaRegisterLinkedBinary%ModuleID%(void (*)(void *), void *,
// void *, void (*)(void **))
SmallString<128> RegisterLinkedBinaryName("__cudaRegisterLinkedBinary");
RegisterLinkedBinaryName += ModuleID;
llvm::Constant *RegisterLinkedBinaryFunc = CGM.CreateRuntimeFunction(
getRegisterLinkedBinaryFnTy(), RegisterLinkedBinaryName);
assert(RegisterGlobalsFunc && "Expecting at least dummy function!");
llvm::Value *Args[] = {RegisterGlobalsFunc,
CtorBuilder.CreateBitCast(FatbinWrapper, VoidPtrTy),
ModuleIDConstant,
makeDummyFunction(getCallbackFnTy())};
CtorBuilder.CreateCall(RegisterLinkedBinaryFunc, Args);
}
// Create destructor and register it with atexit() the way NVCC does it. Doing
// it during regular destructor phase worked in CUDA before 9.2 but results in
// double-free in 9.2.
if (llvm::Function *CleanupFn = makeModuleDtorFunction()) {
// extern "C" int atexit(void (*f)(void));
llvm::FunctionType *AtExitTy =
llvm::FunctionType::get(IntTy, CleanupFn->getType(), false);
llvm::Constant *AtExitFunc =
CGM.CreateRuntimeFunction(AtExitTy, "atexit", llvm::AttributeList(),
/*Local=*/true);
CtorBuilder.CreateCall(AtExitFunc, CleanupFn);
}
CtorBuilder.CreateRetVoid();
return ModuleCtorFunc;
}
/// Creates a global destructor function that unregisters the GPU code blob
/// registered by constructor.
///
/// For CUDA:
/// \code
/// void __cuda_module_dtor(void*) {
/// __cudaUnregisterFatBinary(Handle);
/// }
/// \endcode
///
/// For HIP:
/// \code
/// void __hip_module_dtor(void*) {
/// if (__hip_gpubin_handle) {
/// __hipUnregisterFatBinary(__hip_gpubin_handle);
/// __hip_gpubin_handle = 0;
/// }
/// }
/// \endcode
llvm::Function *CGNVCUDARuntime::makeModuleDtorFunction() {
// No need for destructor if we don't have a handle to unregister.
if (!GpuBinaryHandle)
return nullptr;
// void __cudaUnregisterFatBinary(void ** handle);
llvm::Constant *UnregisterFatbinFunc = CGM.CreateRuntimeFunction(
llvm::FunctionType::get(VoidTy, VoidPtrPtrTy, false),
addUnderscoredPrefixToName("UnregisterFatBinary"));
llvm::Function *ModuleDtorFunc = llvm::Function::Create(
llvm::FunctionType::get(VoidTy, VoidPtrTy, false),
llvm::GlobalValue::InternalLinkage,
addUnderscoredPrefixToName("_module_dtor"), &TheModule);
llvm::BasicBlock *DtorEntryBB =
llvm::BasicBlock::Create(Context, "entry", ModuleDtorFunc);
CGBuilderTy DtorBuilder(CGM, Context);
DtorBuilder.SetInsertPoint(DtorEntryBB);
Address GpuBinaryAddr(GpuBinaryHandle, CharUnits::fromQuantity(
GpuBinaryHandle->getAlignment()));
auto HandleValue = DtorBuilder.CreateLoad(GpuBinaryAddr);
// There is only one HIP fat binary per linked module, however there are
// multiple destructor functions. Make sure the fat binary is unregistered
// only once.
if (CGM.getLangOpts().HIP) {
llvm::BasicBlock *IfBlock =
llvm::BasicBlock::Create(Context, "if", ModuleDtorFunc);
llvm::BasicBlock *ExitBlock =
llvm::BasicBlock::Create(Context, "exit", ModuleDtorFunc);
llvm::Constant *Zero = llvm::Constant::getNullValue(HandleValue->getType());
llvm::Value *NEZero = DtorBuilder.CreateICmpNE(HandleValue, Zero);
DtorBuilder.CreateCondBr(NEZero, IfBlock, ExitBlock);
DtorBuilder.SetInsertPoint(IfBlock);
DtorBuilder.CreateCall(UnregisterFatbinFunc, HandleValue);
DtorBuilder.CreateStore(Zero, GpuBinaryAddr);
DtorBuilder.CreateBr(ExitBlock);
DtorBuilder.SetInsertPoint(ExitBlock);
} else {
DtorBuilder.CreateCall(UnregisterFatbinFunc, HandleValue);
}
DtorBuilder.CreateRetVoid();
return ModuleDtorFunc;
}
CGCUDARuntime *CodeGen::CreateNVCUDARuntime(CodeGenModule &CGM) {
return new CGNVCUDARuntime(CGM);
}
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