1 //===----- CGCUDANV.cpp - Interface to NVIDIA CUDA Runtime ----------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This provides a class for CUDA code generation targeting the NVIDIA CUDA
11 // runtime library.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "CGCUDARuntime.h"
16 #include "CodeGenFunction.h"
17 #include "CodeGenModule.h"
18 #include "clang/AST/Decl.h"
19 #include "llvm/IR/BasicBlock.h"
20 #include "llvm/IR/CallSite.h"
21 #include "llvm/IR/Constants.h"
22 #include "llvm/IR/DerivedTypes.h"
23
24 using namespace clang;
25 using namespace CodeGen;
26
27 namespace {
28
29 class CGNVCUDARuntime : public CGCUDARuntime {
30
31 private:
32 llvm::Type *IntTy, *SizeTy, *VoidTy;
33 llvm::PointerType *CharPtrTy, *VoidPtrTy, *VoidPtrPtrTy;
34
35 /// Convenience reference to LLVM Context
36 llvm::LLVMContext &Context;
37 /// Convenience reference to the current module
38 llvm::Module &TheModule;
39 /// Keeps track of kernel launch stubs emitted in this module
40 llvm::SmallVector<llvm::Function *, 16> EmittedKernels;
41 /// Keeps track of variables containing handles of GPU binaries. Populated by
42 /// ModuleCtorFunction() and used to create corresponding cleanup calls in
43 /// ModuleDtorFunction()
44 llvm::SmallVector<llvm::GlobalVariable *, 16> GpuBinaryHandles;
45
46 llvm::Constant *getSetupArgumentFn() const;
47 llvm::Constant *getLaunchFn() const;
48
49 /// Creates a function to register all kernel stubs generated in this module.
50 llvm::Function *makeRegisterKernelsFn();
51
52 /// Helper function that generates a constant string and returns a pointer to
53 /// the start of the string. The result of this function can be used anywhere
54 /// where the C code specifies const char*.
makeConstantString(const std::string & Str,const std::string & Name="",unsigned Alignment=0)55 llvm::Constant *makeConstantString(const std::string &Str,
56 const std::string &Name = "",
57 unsigned Alignment = 0) {
58 llvm::Constant *Zeros[] = {llvm::ConstantInt::get(SizeTy, 0),
59 llvm::ConstantInt::get(SizeTy, 0)};
60 auto ConstStr = CGM.GetAddrOfConstantCString(Str, Name.c_str());
61 return llvm::ConstantExpr::getGetElementPtr(ConstStr.getElementType(),
62 ConstStr.getPointer(), Zeros);
63 }
64
65 void emitDeviceStubBody(CodeGenFunction &CGF, FunctionArgList &Args);
66
67 public:
68 CGNVCUDARuntime(CodeGenModule &CGM);
69
70 void emitDeviceStub(CodeGenFunction &CGF, FunctionArgList &Args) override;
71 /// Creates module constructor function
72 llvm::Function *makeModuleCtorFunction() override;
73 /// Creates module destructor function
74 llvm::Function *makeModuleDtorFunction() override;
75 };
76
77 }
78
CGNVCUDARuntime(CodeGenModule & CGM)79 CGNVCUDARuntime::CGNVCUDARuntime(CodeGenModule &CGM)
80 : CGCUDARuntime(CGM), Context(CGM.getLLVMContext()),
81 TheModule(CGM.getModule()) {
82 CodeGen::CodeGenTypes &Types = CGM.getTypes();
83 ASTContext &Ctx = CGM.getContext();
84
85 IntTy = Types.ConvertType(Ctx.IntTy);
86 SizeTy = Types.ConvertType(Ctx.getSizeType());
87 VoidTy = llvm::Type::getVoidTy(Context);
88
89 CharPtrTy = llvm::PointerType::getUnqual(Types.ConvertType(Ctx.CharTy));
90 VoidPtrTy = cast<llvm::PointerType>(Types.ConvertType(Ctx.VoidPtrTy));
91 VoidPtrPtrTy = VoidPtrTy->getPointerTo();
92 }
93
getSetupArgumentFn() const94 llvm::Constant *CGNVCUDARuntime::getSetupArgumentFn() const {
95 // cudaError_t cudaSetupArgument(void *, size_t, size_t)
96 std::vector<llvm::Type*> Params;
97 Params.push_back(VoidPtrTy);
98 Params.push_back(SizeTy);
99 Params.push_back(SizeTy);
100 return CGM.CreateRuntimeFunction(llvm::FunctionType::get(IntTy,
101 Params, false),
102 "cudaSetupArgument");
103 }
104
getLaunchFn() const105 llvm::Constant *CGNVCUDARuntime::getLaunchFn() const {
106 // cudaError_t cudaLaunch(char *)
107 return CGM.CreateRuntimeFunction(
108 llvm::FunctionType::get(IntTy, CharPtrTy, false), "cudaLaunch");
109 }
110
emitDeviceStub(CodeGenFunction & CGF,FunctionArgList & Args)111 void CGNVCUDARuntime::emitDeviceStub(CodeGenFunction &CGF,
112 FunctionArgList &Args) {
113 EmittedKernels.push_back(CGF.CurFn);
114 emitDeviceStubBody(CGF, Args);
115 }
116
emitDeviceStubBody(CodeGenFunction & CGF,FunctionArgList & Args)117 void CGNVCUDARuntime::emitDeviceStubBody(CodeGenFunction &CGF,
118 FunctionArgList &Args) {
119 // Build the argument value list and the argument stack struct type.
120 SmallVector<llvm::Value *, 16> ArgValues;
121 std::vector<llvm::Type *> ArgTypes;
122 for (FunctionArgList::const_iterator I = Args.begin(), E = Args.end();
123 I != E; ++I) {
124 llvm::Value *V = CGF.GetAddrOfLocalVar(*I).getPointer();
125 ArgValues.push_back(V);
126 assert(isa<llvm::PointerType>(V->getType()) && "Arg type not PointerType");
127 ArgTypes.push_back(cast<llvm::PointerType>(V->getType())->getElementType());
128 }
129 llvm::StructType *ArgStackTy = llvm::StructType::get(Context, ArgTypes);
130
131 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("setup.end");
132
133 // Emit the calls to cudaSetupArgument
134 llvm::Constant *cudaSetupArgFn = getSetupArgumentFn();
135 for (unsigned I = 0, E = Args.size(); I != E; ++I) {
136 llvm::Value *Args[3];
137 llvm::BasicBlock *NextBlock = CGF.createBasicBlock("setup.next");
138 Args[0] = CGF.Builder.CreatePointerCast(ArgValues[I], VoidPtrTy);
139 Args[1] = CGF.Builder.CreateIntCast(
140 llvm::ConstantExpr::getSizeOf(ArgTypes[I]),
141 SizeTy, false);
142 Args[2] = CGF.Builder.CreateIntCast(
143 llvm::ConstantExpr::getOffsetOf(ArgStackTy, I),
144 SizeTy, false);
145 llvm::CallSite CS = CGF.EmitRuntimeCallOrInvoke(cudaSetupArgFn, Args);
146 llvm::Constant *Zero = llvm::ConstantInt::get(IntTy, 0);
147 llvm::Value *CSZero = CGF.Builder.CreateICmpEQ(CS.getInstruction(), Zero);
148 CGF.Builder.CreateCondBr(CSZero, NextBlock, EndBlock);
149 CGF.EmitBlock(NextBlock);
150 }
151
152 // Emit the call to cudaLaunch
153 llvm::Constant *cudaLaunchFn = getLaunchFn();
154 llvm::Value *Arg = CGF.Builder.CreatePointerCast(CGF.CurFn, CharPtrTy);
155 CGF.EmitRuntimeCallOrInvoke(cudaLaunchFn, Arg);
156 CGF.EmitBranch(EndBlock);
157
158 CGF.EmitBlock(EndBlock);
159 }
160
161 /// Creates internal function to register all kernel stubs generated in this
162 /// module with the CUDA runtime.
163 /// \code
164 /// void __cuda_register_kernels(void** GpuBinaryHandle) {
165 /// __cudaRegisterFunction(GpuBinaryHandle,Kernel0,...);
166 /// ...
167 /// __cudaRegisterFunction(GpuBinaryHandle,KernelM,...);
168 /// }
169 /// \endcode
makeRegisterKernelsFn()170 llvm::Function *CGNVCUDARuntime::makeRegisterKernelsFn() {
171 llvm::Function *RegisterKernelsFunc = llvm::Function::Create(
172 llvm::FunctionType::get(VoidTy, VoidPtrPtrTy, false),
173 llvm::GlobalValue::InternalLinkage, "__cuda_register_kernels", &TheModule);
174 llvm::BasicBlock *EntryBB =
175 llvm::BasicBlock::Create(Context, "entry", RegisterKernelsFunc);
176 CGBuilderTy Builder(CGM, Context);
177 Builder.SetInsertPoint(EntryBB);
178
179 // void __cudaRegisterFunction(void **, const char *, char *, const char *,
180 // int, uint3*, uint3*, dim3*, dim3*, int*)
181 std::vector<llvm::Type *> RegisterFuncParams = {
182 VoidPtrPtrTy, CharPtrTy, CharPtrTy, CharPtrTy, IntTy,
183 VoidPtrTy, VoidPtrTy, VoidPtrTy, VoidPtrTy, IntTy->getPointerTo()};
184 llvm::Constant *RegisterFunc = CGM.CreateRuntimeFunction(
185 llvm::FunctionType::get(IntTy, RegisterFuncParams, false),
186 "__cudaRegisterFunction");
187
188 // Extract GpuBinaryHandle passed as the first argument passed to
189 // __cuda_register_kernels() and generate __cudaRegisterFunction() call for
190 // each emitted kernel.
191 llvm::Argument &GpuBinaryHandlePtr = *RegisterKernelsFunc->arg_begin();
192 for (llvm::Function *Kernel : EmittedKernels) {
193 llvm::Constant *KernelName = makeConstantString(Kernel->getName());
194 llvm::Constant *NullPtr = llvm::ConstantPointerNull::get(VoidPtrTy);
195 llvm::Value *args[] = {
196 &GpuBinaryHandlePtr, Builder.CreateBitCast(Kernel, VoidPtrTy),
197 KernelName, KernelName, llvm::ConstantInt::get(IntTy, -1), NullPtr,
198 NullPtr, NullPtr, NullPtr,
199 llvm::ConstantPointerNull::get(IntTy->getPointerTo())};
200 Builder.CreateCall(RegisterFunc, args);
201 }
202
203 Builder.CreateRetVoid();
204 return RegisterKernelsFunc;
205 }
206
207 /// Creates a global constructor function for the module:
208 /// \code
209 /// void __cuda_module_ctor(void*) {
210 /// Handle0 = __cudaRegisterFatBinary(GpuBinaryBlob0);
211 /// __cuda_register_kernels(Handle0);
212 /// ...
213 /// HandleN = __cudaRegisterFatBinary(GpuBinaryBlobN);
214 /// __cuda_register_kernels(HandleN);
215 /// }
216 /// \endcode
makeModuleCtorFunction()217 llvm::Function *CGNVCUDARuntime::makeModuleCtorFunction() {
218 // void __cuda_register_kernels(void* handle);
219 llvm::Function *RegisterKernelsFunc = makeRegisterKernelsFn();
220 // void ** __cudaRegisterFatBinary(void *);
221 llvm::Constant *RegisterFatbinFunc = CGM.CreateRuntimeFunction(
222 llvm::FunctionType::get(VoidPtrPtrTy, VoidPtrTy, false),
223 "__cudaRegisterFatBinary");
224 // struct { int magic, int version, void * gpu_binary, void * dont_care };
225 llvm::StructType *FatbinWrapperTy =
226 llvm::StructType::get(IntTy, IntTy, VoidPtrTy, VoidPtrTy, nullptr);
227
228 llvm::Function *ModuleCtorFunc = llvm::Function::Create(
229 llvm::FunctionType::get(VoidTy, VoidPtrTy, false),
230 llvm::GlobalValue::InternalLinkage, "__cuda_module_ctor", &TheModule);
231 llvm::BasicBlock *CtorEntryBB =
232 llvm::BasicBlock::Create(Context, "entry", ModuleCtorFunc);
233 CGBuilderTy CtorBuilder(CGM, Context);
234
235 CtorBuilder.SetInsertPoint(CtorEntryBB);
236
237 // For each GPU binary, register it with the CUDA runtime and store returned
238 // handle in a global variable and save the handle in GpuBinaryHandles vector
239 // to be cleaned up in destructor on exit. Then associate all known kernels
240 // with the GPU binary handle so CUDA runtime can figure out what to call on
241 // the GPU side.
242 for (const std::string &GpuBinaryFileName :
243 CGM.getCodeGenOpts().CudaGpuBinaryFileNames) {
244 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> GpuBinaryOrErr =
245 llvm::MemoryBuffer::getFileOrSTDIN(GpuBinaryFileName);
246 if (std::error_code EC = GpuBinaryOrErr.getError()) {
247 CGM.getDiags().Report(diag::err_cannot_open_file) << GpuBinaryFileName
248 << EC.message();
249 continue;
250 }
251
252 // Create initialized wrapper structure that points to the loaded GPU binary
253 llvm::Constant *Values[] = {
254 llvm::ConstantInt::get(IntTy, 0x466243b1), // Fatbin wrapper magic.
255 llvm::ConstantInt::get(IntTy, 1), // Fatbin version.
256 makeConstantString(GpuBinaryOrErr.get()->getBuffer(), "", 16), // Data.
257 llvm::ConstantPointerNull::get(VoidPtrTy)}; // Unused in fatbin v1.
258 llvm::GlobalVariable *FatbinWrapper = new llvm::GlobalVariable(
259 TheModule, FatbinWrapperTy, true, llvm::GlobalValue::InternalLinkage,
260 llvm::ConstantStruct::get(FatbinWrapperTy, Values),
261 "__cuda_fatbin_wrapper");
262
263 // GpuBinaryHandle = __cudaRegisterFatBinary(&FatbinWrapper);
264 llvm::CallInst *RegisterFatbinCall = CtorBuilder.CreateCall(
265 RegisterFatbinFunc,
266 CtorBuilder.CreateBitCast(FatbinWrapper, VoidPtrTy));
267 llvm::GlobalVariable *GpuBinaryHandle = new llvm::GlobalVariable(
268 TheModule, VoidPtrPtrTy, false, llvm::GlobalValue::InternalLinkage,
269 llvm::ConstantPointerNull::get(VoidPtrPtrTy), "__cuda_gpubin_handle");
270 CtorBuilder.CreateAlignedStore(RegisterFatbinCall, GpuBinaryHandle,
271 CGM.getPointerAlign());
272
273 // Call __cuda_register_kernels(GpuBinaryHandle);
274 CtorBuilder.CreateCall(RegisterKernelsFunc, RegisterFatbinCall);
275
276 // Save GpuBinaryHandle so we can unregister it in destructor.
277 GpuBinaryHandles.push_back(GpuBinaryHandle);
278 }
279
280 CtorBuilder.CreateRetVoid();
281 return ModuleCtorFunc;
282 }
283
284 /// Creates a global destructor function that unregisters all GPU code blobs
285 /// registered by constructor.
286 /// \code
287 /// void __cuda_module_dtor(void*) {
288 /// __cudaUnregisterFatBinary(Handle0);
289 /// ...
290 /// __cudaUnregisterFatBinary(HandleN);
291 /// }
292 /// \endcode
makeModuleDtorFunction()293 llvm::Function *CGNVCUDARuntime::makeModuleDtorFunction() {
294 // void __cudaUnregisterFatBinary(void ** handle);
295 llvm::Constant *UnregisterFatbinFunc = CGM.CreateRuntimeFunction(
296 llvm::FunctionType::get(VoidTy, VoidPtrPtrTy, false),
297 "__cudaUnregisterFatBinary");
298
299 llvm::Function *ModuleDtorFunc = llvm::Function::Create(
300 llvm::FunctionType::get(VoidTy, VoidPtrTy, false),
301 llvm::GlobalValue::InternalLinkage, "__cuda_module_dtor", &TheModule);
302 llvm::BasicBlock *DtorEntryBB =
303 llvm::BasicBlock::Create(Context, "entry", ModuleDtorFunc);
304 CGBuilderTy DtorBuilder(CGM, Context);
305 DtorBuilder.SetInsertPoint(DtorEntryBB);
306
307 for (llvm::GlobalVariable *GpuBinaryHandle : GpuBinaryHandles) {
308 auto HandleValue =
309 DtorBuilder.CreateAlignedLoad(GpuBinaryHandle, CGM.getPointerAlign());
310 DtorBuilder.CreateCall(UnregisterFatbinFunc, HandleValue);
311 }
312
313 DtorBuilder.CreateRetVoid();
314 return ModuleDtorFunc;
315 }
316
CreateNVCUDARuntime(CodeGenModule & CGM)317 CGCUDARuntime *CodeGen::CreateNVCUDARuntime(CodeGenModule &CGM) {
318 return new CGNVCUDARuntime(CGM);
319 }
320