xref: /freebsd/contrib/llvm-project/clang/lib/CodeGen/CGCUDANV.cpp (revision 6966ac055c3b7a39266fb982493330df7a097997)
1 //===----- CGCUDANV.cpp - Interface to NVIDIA CUDA Runtime ----------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This provides a class for CUDA code generation targeting the NVIDIA CUDA
10 // runtime library.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "CGCUDARuntime.h"
15 #include "CodeGenFunction.h"
16 #include "CodeGenModule.h"
17 #include "clang/AST/Decl.h"
18 #include "clang/Basic/Cuda.h"
19 #include "clang/CodeGen/CodeGenABITypes.h"
20 #include "clang/CodeGen/ConstantInitBuilder.h"
21 #include "llvm/IR/BasicBlock.h"
22 #include "llvm/IR/Constants.h"
23 #include "llvm/IR/DerivedTypes.h"
24 #include "llvm/Support/Format.h"
25 
26 using namespace clang;
27 using namespace CodeGen;
28 
29 namespace {
30 constexpr unsigned CudaFatMagic = 0x466243b1;
31 constexpr unsigned HIPFatMagic = 0x48495046; // "HIPF"
32 
33 class CGNVCUDARuntime : public CGCUDARuntime {
34 
35 private:
36   llvm::IntegerType *IntTy, *SizeTy;
37   llvm::Type *VoidTy;
38   llvm::PointerType *CharPtrTy, *VoidPtrTy, *VoidPtrPtrTy;
39 
40   /// Convenience reference to LLVM Context
41   llvm::LLVMContext &Context;
42   /// Convenience reference to the current module
43   llvm::Module &TheModule;
44   /// Keeps track of kernel launch stubs emitted in this module
45   struct KernelInfo {
46     llvm::Function *Kernel;
47     const Decl *D;
48   };
49   llvm::SmallVector<KernelInfo, 16> EmittedKernels;
50   struct VarInfo {
51     llvm::GlobalVariable *Var;
52     const VarDecl *D;
53     unsigned Flag;
54   };
55   llvm::SmallVector<VarInfo, 16> DeviceVars;
56   /// Keeps track of variable containing handle of GPU binary. Populated by
57   /// ModuleCtorFunction() and used to create corresponding cleanup calls in
58   /// ModuleDtorFunction()
59   llvm::GlobalVariable *GpuBinaryHandle = nullptr;
60   /// Whether we generate relocatable device code.
61   bool RelocatableDeviceCode;
62   /// Mangle context for device.
63   std::unique_ptr<MangleContext> DeviceMC;
64 
65   llvm::FunctionCallee getSetupArgumentFn() const;
66   llvm::FunctionCallee getLaunchFn() const;
67 
68   llvm::FunctionType *getRegisterGlobalsFnTy() const;
69   llvm::FunctionType *getCallbackFnTy() const;
70   llvm::FunctionType *getRegisterLinkedBinaryFnTy() const;
71   std::string addPrefixToName(StringRef FuncName) const;
72   std::string addUnderscoredPrefixToName(StringRef FuncName) const;
73 
74   /// Creates a function to register all kernel stubs generated in this module.
75   llvm::Function *makeRegisterGlobalsFn();
76 
77   /// Helper function that generates a constant string and returns a pointer to
78   /// the start of the string.  The result of this function can be used anywhere
79   /// where the C code specifies const char*.
80   llvm::Constant *makeConstantString(const std::string &Str,
81                                      const std::string &Name = "",
82                                      const std::string &SectionName = "",
83                                      unsigned Alignment = 0) {
84     llvm::Constant *Zeros[] = {llvm::ConstantInt::get(SizeTy, 0),
85                                llvm::ConstantInt::get(SizeTy, 0)};
86     auto ConstStr = CGM.GetAddrOfConstantCString(Str, Name.c_str());
87     llvm::GlobalVariable *GV =
88         cast<llvm::GlobalVariable>(ConstStr.getPointer());
89     if (!SectionName.empty()) {
90       GV->setSection(SectionName);
91       // Mark the address as used which make sure that this section isn't
92       // merged and we will really have it in the object file.
93       GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::None);
94     }
95     if (Alignment)
96       GV->setAlignment(Alignment);
97 
98     return llvm::ConstantExpr::getGetElementPtr(ConstStr.getElementType(),
99                                                 ConstStr.getPointer(), Zeros);
100   }
101 
102   /// Helper function that generates an empty dummy function returning void.
103   llvm::Function *makeDummyFunction(llvm::FunctionType *FnTy) {
104     assert(FnTy->getReturnType()->isVoidTy() &&
105            "Can only generate dummy functions returning void!");
106     llvm::Function *DummyFunc = llvm::Function::Create(
107         FnTy, llvm::GlobalValue::InternalLinkage, "dummy", &TheModule);
108 
109     llvm::BasicBlock *DummyBlock =
110         llvm::BasicBlock::Create(Context, "", DummyFunc);
111     CGBuilderTy FuncBuilder(CGM, Context);
112     FuncBuilder.SetInsertPoint(DummyBlock);
113     FuncBuilder.CreateRetVoid();
114 
115     return DummyFunc;
116   }
117 
118   void emitDeviceStubBodyLegacy(CodeGenFunction &CGF, FunctionArgList &Args);
119   void emitDeviceStubBodyNew(CodeGenFunction &CGF, FunctionArgList &Args);
120   std::string getDeviceSideName(const Decl *ND);
121 
122 public:
123   CGNVCUDARuntime(CodeGenModule &CGM);
124 
125   void emitDeviceStub(CodeGenFunction &CGF, FunctionArgList &Args) override;
126   void registerDeviceVar(const VarDecl *VD, llvm::GlobalVariable &Var,
127                          unsigned Flags) override {
128     DeviceVars.push_back({&Var, VD, Flags});
129   }
130 
131   /// Creates module constructor function
132   llvm::Function *makeModuleCtorFunction() override;
133   /// Creates module destructor function
134   llvm::Function *makeModuleDtorFunction() override;
135   /// Construct and return the stub name of a kernel.
136   std::string getDeviceStubName(llvm::StringRef Name) const override;
137 };
138 
139 }
140 
141 std::string CGNVCUDARuntime::addPrefixToName(StringRef FuncName) const {
142   if (CGM.getLangOpts().HIP)
143     return ((Twine("hip") + Twine(FuncName)).str());
144   return ((Twine("cuda") + Twine(FuncName)).str());
145 }
146 std::string
147 CGNVCUDARuntime::addUnderscoredPrefixToName(StringRef FuncName) const {
148   if (CGM.getLangOpts().HIP)
149     return ((Twine("__hip") + Twine(FuncName)).str());
150   return ((Twine("__cuda") + Twine(FuncName)).str());
151 }
152 
153 CGNVCUDARuntime::CGNVCUDARuntime(CodeGenModule &CGM)
154     : CGCUDARuntime(CGM), Context(CGM.getLLVMContext()),
155       TheModule(CGM.getModule()),
156       RelocatableDeviceCode(CGM.getLangOpts().GPURelocatableDeviceCode),
157       DeviceMC(CGM.getContext().createMangleContext(
158           CGM.getContext().getAuxTargetInfo())) {
159   CodeGen::CodeGenTypes &Types = CGM.getTypes();
160   ASTContext &Ctx = CGM.getContext();
161 
162   IntTy = CGM.IntTy;
163   SizeTy = CGM.SizeTy;
164   VoidTy = CGM.VoidTy;
165 
166   CharPtrTy = llvm::PointerType::getUnqual(Types.ConvertType(Ctx.CharTy));
167   VoidPtrTy = cast<llvm::PointerType>(Types.ConvertType(Ctx.VoidPtrTy));
168   VoidPtrPtrTy = VoidPtrTy->getPointerTo();
169 }
170 
171 llvm::FunctionCallee CGNVCUDARuntime::getSetupArgumentFn() const {
172   // cudaError_t cudaSetupArgument(void *, size_t, size_t)
173   llvm::Type *Params[] = {VoidPtrTy, SizeTy, SizeTy};
174   return CGM.CreateRuntimeFunction(
175       llvm::FunctionType::get(IntTy, Params, false),
176       addPrefixToName("SetupArgument"));
177 }
178 
179 llvm::FunctionCallee CGNVCUDARuntime::getLaunchFn() const {
180   if (CGM.getLangOpts().HIP) {
181     // hipError_t hipLaunchByPtr(char *);
182     return CGM.CreateRuntimeFunction(
183         llvm::FunctionType::get(IntTy, CharPtrTy, false), "hipLaunchByPtr");
184   } else {
185     // cudaError_t cudaLaunch(char *);
186     return CGM.CreateRuntimeFunction(
187         llvm::FunctionType::get(IntTy, CharPtrTy, false), "cudaLaunch");
188   }
189 }
190 
191 llvm::FunctionType *CGNVCUDARuntime::getRegisterGlobalsFnTy() const {
192   return llvm::FunctionType::get(VoidTy, VoidPtrPtrTy, false);
193 }
194 
195 llvm::FunctionType *CGNVCUDARuntime::getCallbackFnTy() const {
196   return llvm::FunctionType::get(VoidTy, VoidPtrTy, false);
197 }
198 
199 llvm::FunctionType *CGNVCUDARuntime::getRegisterLinkedBinaryFnTy() const {
200   auto CallbackFnTy = getCallbackFnTy();
201   auto RegisterGlobalsFnTy = getRegisterGlobalsFnTy();
202   llvm::Type *Params[] = {RegisterGlobalsFnTy->getPointerTo(), VoidPtrTy,
203                           VoidPtrTy, CallbackFnTy->getPointerTo()};
204   return llvm::FunctionType::get(VoidTy, Params, false);
205 }
206 
207 std::string CGNVCUDARuntime::getDeviceSideName(const Decl *D) {
208   auto *ND = cast<const NamedDecl>(D);
209   std::string DeviceSideName;
210   if (DeviceMC->shouldMangleDeclName(ND)) {
211     SmallString<256> Buffer;
212     llvm::raw_svector_ostream Out(Buffer);
213     DeviceMC->mangleName(ND, Out);
214     DeviceSideName = Out.str();
215   } else
216     DeviceSideName = ND->getIdentifier()->getName();
217   return DeviceSideName;
218 }
219 
220 void CGNVCUDARuntime::emitDeviceStub(CodeGenFunction &CGF,
221                                      FunctionArgList &Args) {
222   // Ensure either we have different ABIs between host and device compilations,
223   // says host compilation following MSVC ABI but device compilation follows
224   // Itanium C++ ABI or, if they follow the same ABI, kernel names after
225   // mangling should be the same after name stubbing. The later checking is
226   // very important as the device kernel name being mangled in host-compilation
227   // is used to resolve the device binaries to be executed. Inconsistent naming
228   // result in undefined behavior. Even though we cannot check that naming
229   // directly between host- and device-compilations, the host- and
230   // device-mangling in host compilation could help catching certain ones.
231   assert((CGF.CGM.getContext().getAuxTargetInfo() &&
232           (CGF.CGM.getContext().getAuxTargetInfo()->getCXXABI() !=
233            CGF.CGM.getContext().getTargetInfo().getCXXABI())) ||
234          getDeviceStubName(getDeviceSideName(CGF.CurFuncDecl)) ==
235              CGF.CurFn->getName());
236 
237   EmittedKernels.push_back({CGF.CurFn, CGF.CurFuncDecl});
238   if (CudaFeatureEnabled(CGM.getTarget().getSDKVersion(),
239                          CudaFeature::CUDA_USES_NEW_LAUNCH))
240     emitDeviceStubBodyNew(CGF, Args);
241   else
242     emitDeviceStubBodyLegacy(CGF, Args);
243 }
244 
245 // CUDA 9.0+ uses new way to launch kernels. Parameters are packed in a local
246 // array and kernels are launched using cudaLaunchKernel().
247 void CGNVCUDARuntime::emitDeviceStubBodyNew(CodeGenFunction &CGF,
248                                             FunctionArgList &Args) {
249   // Build the shadow stack entry at the very start of the function.
250 
251   // Calculate amount of space we will need for all arguments.  If we have no
252   // args, allocate a single pointer so we still have a valid pointer to the
253   // argument array that we can pass to runtime, even if it will be unused.
254   Address KernelArgs = CGF.CreateTempAlloca(
255       VoidPtrTy, CharUnits::fromQuantity(16), "kernel_args",
256       llvm::ConstantInt::get(SizeTy, std::max<size_t>(1, Args.size())));
257   // Store pointers to the arguments in a locally allocated launch_args.
258   for (unsigned i = 0; i < Args.size(); ++i) {
259     llvm::Value* VarPtr = CGF.GetAddrOfLocalVar(Args[i]).getPointer();
260     llvm::Value *VoidVarPtr = CGF.Builder.CreatePointerCast(VarPtr, VoidPtrTy);
261     CGF.Builder.CreateDefaultAlignedStore(
262         VoidVarPtr, CGF.Builder.CreateConstGEP1_32(KernelArgs.getPointer(), i));
263   }
264 
265   llvm::BasicBlock *EndBlock = CGF.createBasicBlock("setup.end");
266 
267   // Lookup cudaLaunchKernel function.
268   // cudaError_t cudaLaunchKernel(const void *func, dim3 gridDim, dim3 blockDim,
269   //                              void **args, size_t sharedMem,
270   //                              cudaStream_t stream);
271   TranslationUnitDecl *TUDecl = CGM.getContext().getTranslationUnitDecl();
272   DeclContext *DC = TranslationUnitDecl::castToDeclContext(TUDecl);
273   IdentifierInfo &cudaLaunchKernelII =
274       CGM.getContext().Idents.get("cudaLaunchKernel");
275   FunctionDecl *cudaLaunchKernelFD = nullptr;
276   for (const auto &Result : DC->lookup(&cudaLaunchKernelII)) {
277     if (FunctionDecl *FD = dyn_cast<FunctionDecl>(Result))
278       cudaLaunchKernelFD = FD;
279   }
280 
281   if (cudaLaunchKernelFD == nullptr) {
282     CGM.Error(CGF.CurFuncDecl->getLocation(),
283               "Can't find declaration for cudaLaunchKernel()");
284     return;
285   }
286   // Create temporary dim3 grid_dim, block_dim.
287   ParmVarDecl *GridDimParam = cudaLaunchKernelFD->getParamDecl(1);
288   QualType Dim3Ty = GridDimParam->getType();
289   Address GridDim =
290       CGF.CreateMemTemp(Dim3Ty, CharUnits::fromQuantity(8), "grid_dim");
291   Address BlockDim =
292       CGF.CreateMemTemp(Dim3Ty, CharUnits::fromQuantity(8), "block_dim");
293   Address ShmemSize =
294       CGF.CreateTempAlloca(SizeTy, CGM.getSizeAlign(), "shmem_size");
295   Address Stream =
296       CGF.CreateTempAlloca(VoidPtrTy, CGM.getPointerAlign(), "stream");
297   llvm::FunctionCallee cudaPopConfigFn = CGM.CreateRuntimeFunction(
298       llvm::FunctionType::get(IntTy,
299                               {/*gridDim=*/GridDim.getType(),
300                                /*blockDim=*/BlockDim.getType(),
301                                /*ShmemSize=*/ShmemSize.getType(),
302                                /*Stream=*/Stream.getType()},
303                               /*isVarArg=*/false),
304       "__cudaPopCallConfiguration");
305 
306   CGF.EmitRuntimeCallOrInvoke(cudaPopConfigFn,
307                               {GridDim.getPointer(), BlockDim.getPointer(),
308                                ShmemSize.getPointer(), Stream.getPointer()});
309 
310   // Emit the call to cudaLaunch
311   llvm::Value *Kernel = CGF.Builder.CreatePointerCast(CGF.CurFn, VoidPtrTy);
312   CallArgList LaunchKernelArgs;
313   LaunchKernelArgs.add(RValue::get(Kernel),
314                        cudaLaunchKernelFD->getParamDecl(0)->getType());
315   LaunchKernelArgs.add(RValue::getAggregate(GridDim), Dim3Ty);
316   LaunchKernelArgs.add(RValue::getAggregate(BlockDim), Dim3Ty);
317   LaunchKernelArgs.add(RValue::get(KernelArgs.getPointer()),
318                        cudaLaunchKernelFD->getParamDecl(3)->getType());
319   LaunchKernelArgs.add(RValue::get(CGF.Builder.CreateLoad(ShmemSize)),
320                        cudaLaunchKernelFD->getParamDecl(4)->getType());
321   LaunchKernelArgs.add(RValue::get(CGF.Builder.CreateLoad(Stream)),
322                        cudaLaunchKernelFD->getParamDecl(5)->getType());
323 
324   QualType QT = cudaLaunchKernelFD->getType();
325   QualType CQT = QT.getCanonicalType();
326   llvm::Type *Ty = CGM.getTypes().ConvertType(CQT);
327   llvm::FunctionType *FTy = dyn_cast<llvm::FunctionType>(Ty);
328 
329   const CGFunctionInfo &FI =
330       CGM.getTypes().arrangeFunctionDeclaration(cudaLaunchKernelFD);
331   llvm::FunctionCallee cudaLaunchKernelFn =
332       CGM.CreateRuntimeFunction(FTy, "cudaLaunchKernel");
333   CGF.EmitCall(FI, CGCallee::forDirect(cudaLaunchKernelFn), ReturnValueSlot(),
334                LaunchKernelArgs);
335   CGF.EmitBranch(EndBlock);
336 
337   CGF.EmitBlock(EndBlock);
338 }
339 
340 void CGNVCUDARuntime::emitDeviceStubBodyLegacy(CodeGenFunction &CGF,
341                                                FunctionArgList &Args) {
342   // Emit a call to cudaSetupArgument for each arg in Args.
343   llvm::FunctionCallee cudaSetupArgFn = getSetupArgumentFn();
344   llvm::BasicBlock *EndBlock = CGF.createBasicBlock("setup.end");
345   CharUnits Offset = CharUnits::Zero();
346   for (const VarDecl *A : Args) {
347     CharUnits TyWidth, TyAlign;
348     std::tie(TyWidth, TyAlign) =
349         CGM.getContext().getTypeInfoInChars(A->getType());
350     Offset = Offset.alignTo(TyAlign);
351     llvm::Value *Args[] = {
352         CGF.Builder.CreatePointerCast(CGF.GetAddrOfLocalVar(A).getPointer(),
353                                       VoidPtrTy),
354         llvm::ConstantInt::get(SizeTy, TyWidth.getQuantity()),
355         llvm::ConstantInt::get(SizeTy, Offset.getQuantity()),
356     };
357     llvm::CallBase *CB = CGF.EmitRuntimeCallOrInvoke(cudaSetupArgFn, Args);
358     llvm::Constant *Zero = llvm::ConstantInt::get(IntTy, 0);
359     llvm::Value *CBZero = CGF.Builder.CreateICmpEQ(CB, Zero);
360     llvm::BasicBlock *NextBlock = CGF.createBasicBlock("setup.next");
361     CGF.Builder.CreateCondBr(CBZero, NextBlock, EndBlock);
362     CGF.EmitBlock(NextBlock);
363     Offset += TyWidth;
364   }
365 
366   // Emit the call to cudaLaunch
367   llvm::FunctionCallee cudaLaunchFn = getLaunchFn();
368   llvm::Value *Arg = CGF.Builder.CreatePointerCast(CGF.CurFn, CharPtrTy);
369   CGF.EmitRuntimeCallOrInvoke(cudaLaunchFn, Arg);
370   CGF.EmitBranch(EndBlock);
371 
372   CGF.EmitBlock(EndBlock);
373 }
374 
375 /// Creates a function that sets up state on the host side for CUDA objects that
376 /// have a presence on both the host and device sides. Specifically, registers
377 /// the host side of kernel functions and device global variables with the CUDA
378 /// runtime.
379 /// \code
380 /// void __cuda_register_globals(void** GpuBinaryHandle) {
381 ///    __cudaRegisterFunction(GpuBinaryHandle,Kernel0,...);
382 ///    ...
383 ///    __cudaRegisterFunction(GpuBinaryHandle,KernelM,...);
384 ///    __cudaRegisterVar(GpuBinaryHandle, GlobalVar0, ...);
385 ///    ...
386 ///    __cudaRegisterVar(GpuBinaryHandle, GlobalVarN, ...);
387 /// }
388 /// \endcode
389 llvm::Function *CGNVCUDARuntime::makeRegisterGlobalsFn() {
390   // No need to register anything
391   if (EmittedKernels.empty() && DeviceVars.empty())
392     return nullptr;
393 
394   llvm::Function *RegisterKernelsFunc = llvm::Function::Create(
395       getRegisterGlobalsFnTy(), llvm::GlobalValue::InternalLinkage,
396       addUnderscoredPrefixToName("_register_globals"), &TheModule);
397   llvm::BasicBlock *EntryBB =
398       llvm::BasicBlock::Create(Context, "entry", RegisterKernelsFunc);
399   CGBuilderTy Builder(CGM, Context);
400   Builder.SetInsertPoint(EntryBB);
401 
402   // void __cudaRegisterFunction(void **, const char *, char *, const char *,
403   //                             int, uint3*, uint3*, dim3*, dim3*, int*)
404   llvm::Type *RegisterFuncParams[] = {
405       VoidPtrPtrTy, CharPtrTy, CharPtrTy, CharPtrTy, IntTy,
406       VoidPtrTy,    VoidPtrTy, VoidPtrTy, VoidPtrTy, IntTy->getPointerTo()};
407   llvm::FunctionCallee RegisterFunc = CGM.CreateRuntimeFunction(
408       llvm::FunctionType::get(IntTy, RegisterFuncParams, false),
409       addUnderscoredPrefixToName("RegisterFunction"));
410 
411   // Extract GpuBinaryHandle passed as the first argument passed to
412   // __cuda_register_globals() and generate __cudaRegisterFunction() call for
413   // each emitted kernel.
414   llvm::Argument &GpuBinaryHandlePtr = *RegisterKernelsFunc->arg_begin();
415   for (auto &&I : EmittedKernels) {
416     llvm::Constant *KernelName = makeConstantString(getDeviceSideName(I.D));
417     llvm::Constant *NullPtr = llvm::ConstantPointerNull::get(VoidPtrTy);
418     llvm::Value *Args[] = {
419         &GpuBinaryHandlePtr,
420         Builder.CreateBitCast(I.Kernel, VoidPtrTy),
421         KernelName,
422         KernelName,
423         llvm::ConstantInt::get(IntTy, -1),
424         NullPtr,
425         NullPtr,
426         NullPtr,
427         NullPtr,
428         llvm::ConstantPointerNull::get(IntTy->getPointerTo())};
429     Builder.CreateCall(RegisterFunc, Args);
430   }
431 
432   // void __cudaRegisterVar(void **, char *, char *, const char *,
433   //                        int, int, int, int)
434   llvm::Type *RegisterVarParams[] = {VoidPtrPtrTy, CharPtrTy, CharPtrTy,
435                                      CharPtrTy,    IntTy,     IntTy,
436                                      IntTy,        IntTy};
437   llvm::FunctionCallee RegisterVar = CGM.CreateRuntimeFunction(
438       llvm::FunctionType::get(IntTy, RegisterVarParams, false),
439       addUnderscoredPrefixToName("RegisterVar"));
440   for (auto &&Info : DeviceVars) {
441     llvm::GlobalVariable *Var = Info.Var;
442     unsigned Flags = Info.Flag;
443     llvm::Constant *VarName = makeConstantString(getDeviceSideName(Info.D));
444     uint64_t VarSize =
445         CGM.getDataLayout().getTypeAllocSize(Var->getValueType());
446     llvm::Value *Args[] = {
447         &GpuBinaryHandlePtr,
448         Builder.CreateBitCast(Var, VoidPtrTy),
449         VarName,
450         VarName,
451         llvm::ConstantInt::get(IntTy, (Flags & ExternDeviceVar) ? 1 : 0),
452         llvm::ConstantInt::get(IntTy, VarSize),
453         llvm::ConstantInt::get(IntTy, (Flags & ConstantDeviceVar) ? 1 : 0),
454         llvm::ConstantInt::get(IntTy, 0)};
455     Builder.CreateCall(RegisterVar, Args);
456   }
457 
458   Builder.CreateRetVoid();
459   return RegisterKernelsFunc;
460 }
461 
462 /// Creates a global constructor function for the module:
463 ///
464 /// For CUDA:
465 /// \code
466 /// void __cuda_module_ctor(void*) {
467 ///     Handle = __cudaRegisterFatBinary(GpuBinaryBlob);
468 ///     __cuda_register_globals(Handle);
469 /// }
470 /// \endcode
471 ///
472 /// For HIP:
473 /// \code
474 /// void __hip_module_ctor(void*) {
475 ///     if (__hip_gpubin_handle == 0) {
476 ///         __hip_gpubin_handle  = __hipRegisterFatBinary(GpuBinaryBlob);
477 ///         __hip_register_globals(__hip_gpubin_handle);
478 ///     }
479 /// }
480 /// \endcode
481 llvm::Function *CGNVCUDARuntime::makeModuleCtorFunction() {
482   bool IsHIP = CGM.getLangOpts().HIP;
483   bool IsCUDA = CGM.getLangOpts().CUDA;
484   // No need to generate ctors/dtors if there is no GPU binary.
485   StringRef CudaGpuBinaryFileName = CGM.getCodeGenOpts().CudaGpuBinaryFileName;
486   if (CudaGpuBinaryFileName.empty() && !IsHIP)
487     return nullptr;
488   if ((IsHIP || (IsCUDA && !RelocatableDeviceCode)) && EmittedKernels.empty() &&
489       DeviceVars.empty())
490     return nullptr;
491 
492   // void __{cuda|hip}_register_globals(void* handle);
493   llvm::Function *RegisterGlobalsFunc = makeRegisterGlobalsFn();
494   // We always need a function to pass in as callback. Create a dummy
495   // implementation if we don't need to register anything.
496   if (RelocatableDeviceCode && !RegisterGlobalsFunc)
497     RegisterGlobalsFunc = makeDummyFunction(getRegisterGlobalsFnTy());
498 
499   // void ** __{cuda|hip}RegisterFatBinary(void *);
500   llvm::FunctionCallee RegisterFatbinFunc = CGM.CreateRuntimeFunction(
501       llvm::FunctionType::get(VoidPtrPtrTy, VoidPtrTy, false),
502       addUnderscoredPrefixToName("RegisterFatBinary"));
503   // struct { int magic, int version, void * gpu_binary, void * dont_care };
504   llvm::StructType *FatbinWrapperTy =
505       llvm::StructType::get(IntTy, IntTy, VoidPtrTy, VoidPtrTy);
506 
507   // Register GPU binary with the CUDA runtime, store returned handle in a
508   // global variable and save a reference in GpuBinaryHandle to be cleaned up
509   // in destructor on exit. Then associate all known kernels with the GPU binary
510   // handle so CUDA runtime can figure out what to call on the GPU side.
511   std::unique_ptr<llvm::MemoryBuffer> CudaGpuBinary = nullptr;
512   if (!CudaGpuBinaryFileName.empty()) {
513     llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> CudaGpuBinaryOrErr =
514         llvm::MemoryBuffer::getFileOrSTDIN(CudaGpuBinaryFileName);
515     if (std::error_code EC = CudaGpuBinaryOrErr.getError()) {
516       CGM.getDiags().Report(diag::err_cannot_open_file)
517           << CudaGpuBinaryFileName << EC.message();
518       return nullptr;
519     }
520     CudaGpuBinary = std::move(CudaGpuBinaryOrErr.get());
521   }
522 
523   llvm::Function *ModuleCtorFunc = llvm::Function::Create(
524       llvm::FunctionType::get(VoidTy, VoidPtrTy, false),
525       llvm::GlobalValue::InternalLinkage,
526       addUnderscoredPrefixToName("_module_ctor"), &TheModule);
527   llvm::BasicBlock *CtorEntryBB =
528       llvm::BasicBlock::Create(Context, "entry", ModuleCtorFunc);
529   CGBuilderTy CtorBuilder(CGM, Context);
530 
531   CtorBuilder.SetInsertPoint(CtorEntryBB);
532 
533   const char *FatbinConstantName;
534   const char *FatbinSectionName;
535   const char *ModuleIDSectionName;
536   StringRef ModuleIDPrefix;
537   llvm::Constant *FatBinStr;
538   unsigned FatMagic;
539   if (IsHIP) {
540     FatbinConstantName = ".hip_fatbin";
541     FatbinSectionName = ".hipFatBinSegment";
542 
543     ModuleIDSectionName = "__hip_module_id";
544     ModuleIDPrefix = "__hip_";
545 
546     if (CudaGpuBinary) {
547       // If fatbin is available from early finalization, create a string
548       // literal containing the fat binary loaded from the given file.
549       FatBinStr = makeConstantString(CudaGpuBinary->getBuffer(), "",
550                                      FatbinConstantName, 8);
551     } else {
552       // If fatbin is not available, create an external symbol
553       // __hip_fatbin in section .hip_fatbin. The external symbol is supposed
554       // to contain the fat binary but will be populated somewhere else,
555       // e.g. by lld through link script.
556       FatBinStr = new llvm::GlobalVariable(
557         CGM.getModule(), CGM.Int8Ty,
558         /*isConstant=*/true, llvm::GlobalValue::ExternalLinkage, nullptr,
559         "__hip_fatbin", nullptr,
560         llvm::GlobalVariable::NotThreadLocal);
561       cast<llvm::GlobalVariable>(FatBinStr)->setSection(FatbinConstantName);
562     }
563 
564     FatMagic = HIPFatMagic;
565   } else {
566     if (RelocatableDeviceCode)
567       FatbinConstantName = CGM.getTriple().isMacOSX()
568                                ? "__NV_CUDA,__nv_relfatbin"
569                                : "__nv_relfatbin";
570     else
571       FatbinConstantName =
572           CGM.getTriple().isMacOSX() ? "__NV_CUDA,__nv_fatbin" : ".nv_fatbin";
573     // NVIDIA's cuobjdump looks for fatbins in this section.
574     FatbinSectionName =
575         CGM.getTriple().isMacOSX() ? "__NV_CUDA,__fatbin" : ".nvFatBinSegment";
576 
577     ModuleIDSectionName = CGM.getTriple().isMacOSX()
578                               ? "__NV_CUDA,__nv_module_id"
579                               : "__nv_module_id";
580     ModuleIDPrefix = "__nv_";
581 
582     // For CUDA, create a string literal containing the fat binary loaded from
583     // the given file.
584     FatBinStr = makeConstantString(CudaGpuBinary->getBuffer(), "",
585                                    FatbinConstantName, 8);
586     FatMagic = CudaFatMagic;
587   }
588 
589   // Create initialized wrapper structure that points to the loaded GPU binary
590   ConstantInitBuilder Builder(CGM);
591   auto Values = Builder.beginStruct(FatbinWrapperTy);
592   // Fatbin wrapper magic.
593   Values.addInt(IntTy, FatMagic);
594   // Fatbin version.
595   Values.addInt(IntTy, 1);
596   // Data.
597   Values.add(FatBinStr);
598   // Unused in fatbin v1.
599   Values.add(llvm::ConstantPointerNull::get(VoidPtrTy));
600   llvm::GlobalVariable *FatbinWrapper = Values.finishAndCreateGlobal(
601       addUnderscoredPrefixToName("_fatbin_wrapper"), CGM.getPointerAlign(),
602       /*constant*/ true);
603   FatbinWrapper->setSection(FatbinSectionName);
604 
605   // There is only one HIP fat binary per linked module, however there are
606   // multiple constructor functions. Make sure the fat binary is registered
607   // only once. The constructor functions are executed by the dynamic loader
608   // before the program gains control. The dynamic loader cannot execute the
609   // constructor functions concurrently since doing that would not guarantee
610   // thread safety of the loaded program. Therefore we can assume sequential
611   // execution of constructor functions here.
612   if (IsHIP) {
613     auto Linkage = CudaGpuBinary ? llvm::GlobalValue::InternalLinkage :
614         llvm::GlobalValue::LinkOnceAnyLinkage;
615     llvm::BasicBlock *IfBlock =
616         llvm::BasicBlock::Create(Context, "if", ModuleCtorFunc);
617     llvm::BasicBlock *ExitBlock =
618         llvm::BasicBlock::Create(Context, "exit", ModuleCtorFunc);
619     // The name, size, and initialization pattern of this variable is part
620     // of HIP ABI.
621     GpuBinaryHandle = new llvm::GlobalVariable(
622         TheModule, VoidPtrPtrTy, /*isConstant=*/false,
623         Linkage,
624         /*Initializer=*/llvm::ConstantPointerNull::get(VoidPtrPtrTy),
625         "__hip_gpubin_handle");
626     GpuBinaryHandle->setAlignment(CGM.getPointerAlign().getQuantity());
627     // Prevent the weak symbol in different shared libraries being merged.
628     if (Linkage != llvm::GlobalValue::InternalLinkage)
629       GpuBinaryHandle->setVisibility(llvm::GlobalValue::HiddenVisibility);
630     Address GpuBinaryAddr(
631         GpuBinaryHandle,
632         CharUnits::fromQuantity(GpuBinaryHandle->getAlignment()));
633     {
634       auto HandleValue = CtorBuilder.CreateLoad(GpuBinaryAddr);
635       llvm::Constant *Zero =
636           llvm::Constant::getNullValue(HandleValue->getType());
637       llvm::Value *EQZero = CtorBuilder.CreateICmpEQ(HandleValue, Zero);
638       CtorBuilder.CreateCondBr(EQZero, IfBlock, ExitBlock);
639     }
640     {
641       CtorBuilder.SetInsertPoint(IfBlock);
642       // GpuBinaryHandle = __hipRegisterFatBinary(&FatbinWrapper);
643       llvm::CallInst *RegisterFatbinCall = CtorBuilder.CreateCall(
644           RegisterFatbinFunc,
645           CtorBuilder.CreateBitCast(FatbinWrapper, VoidPtrTy));
646       CtorBuilder.CreateStore(RegisterFatbinCall, GpuBinaryAddr);
647       CtorBuilder.CreateBr(ExitBlock);
648     }
649     {
650       CtorBuilder.SetInsertPoint(ExitBlock);
651       // Call __hip_register_globals(GpuBinaryHandle);
652       if (RegisterGlobalsFunc) {
653         auto HandleValue = CtorBuilder.CreateLoad(GpuBinaryAddr);
654         CtorBuilder.CreateCall(RegisterGlobalsFunc, HandleValue);
655       }
656     }
657   } else if (!RelocatableDeviceCode) {
658     // Register binary with CUDA runtime. This is substantially different in
659     // default mode vs. separate compilation!
660     // GpuBinaryHandle = __cudaRegisterFatBinary(&FatbinWrapper);
661     llvm::CallInst *RegisterFatbinCall = CtorBuilder.CreateCall(
662         RegisterFatbinFunc,
663         CtorBuilder.CreateBitCast(FatbinWrapper, VoidPtrTy));
664     GpuBinaryHandle = new llvm::GlobalVariable(
665         TheModule, VoidPtrPtrTy, false, llvm::GlobalValue::InternalLinkage,
666         llvm::ConstantPointerNull::get(VoidPtrPtrTy), "__cuda_gpubin_handle");
667     GpuBinaryHandle->setAlignment(CGM.getPointerAlign().getQuantity());
668     CtorBuilder.CreateAlignedStore(RegisterFatbinCall, GpuBinaryHandle,
669                                    CGM.getPointerAlign());
670 
671     // Call __cuda_register_globals(GpuBinaryHandle);
672     if (RegisterGlobalsFunc)
673       CtorBuilder.CreateCall(RegisterGlobalsFunc, RegisterFatbinCall);
674 
675     // Call __cudaRegisterFatBinaryEnd(Handle) if this CUDA version needs it.
676     if (CudaFeatureEnabled(CGM.getTarget().getSDKVersion(),
677                            CudaFeature::CUDA_USES_FATBIN_REGISTER_END)) {
678       // void __cudaRegisterFatBinaryEnd(void **);
679       llvm::FunctionCallee RegisterFatbinEndFunc = CGM.CreateRuntimeFunction(
680           llvm::FunctionType::get(VoidTy, VoidPtrPtrTy, false),
681           "__cudaRegisterFatBinaryEnd");
682       CtorBuilder.CreateCall(RegisterFatbinEndFunc, RegisterFatbinCall);
683     }
684   } else {
685     // Generate a unique module ID.
686     SmallString<64> ModuleID;
687     llvm::raw_svector_ostream OS(ModuleID);
688     OS << ModuleIDPrefix << llvm::format("%" PRIx64, FatbinWrapper->getGUID());
689     llvm::Constant *ModuleIDConstant =
690         makeConstantString(ModuleID.str(), "", ModuleIDSectionName, 32);
691 
692     // Create an alias for the FatbinWrapper that nvcc will look for.
693     llvm::GlobalAlias::create(llvm::GlobalValue::ExternalLinkage,
694                               Twine("__fatbinwrap") + ModuleID, FatbinWrapper);
695 
696     // void __cudaRegisterLinkedBinary%ModuleID%(void (*)(void *), void *,
697     // void *, void (*)(void **))
698     SmallString<128> RegisterLinkedBinaryName("__cudaRegisterLinkedBinary");
699     RegisterLinkedBinaryName += ModuleID;
700     llvm::FunctionCallee RegisterLinkedBinaryFunc = CGM.CreateRuntimeFunction(
701         getRegisterLinkedBinaryFnTy(), RegisterLinkedBinaryName);
702 
703     assert(RegisterGlobalsFunc && "Expecting at least dummy function!");
704     llvm::Value *Args[] = {RegisterGlobalsFunc,
705                            CtorBuilder.CreateBitCast(FatbinWrapper, VoidPtrTy),
706                            ModuleIDConstant,
707                            makeDummyFunction(getCallbackFnTy())};
708     CtorBuilder.CreateCall(RegisterLinkedBinaryFunc, Args);
709   }
710 
711   // Create destructor and register it with atexit() the way NVCC does it. Doing
712   // it during regular destructor phase worked in CUDA before 9.2 but results in
713   // double-free in 9.2.
714   if (llvm::Function *CleanupFn = makeModuleDtorFunction()) {
715     // extern "C" int atexit(void (*f)(void));
716     llvm::FunctionType *AtExitTy =
717         llvm::FunctionType::get(IntTy, CleanupFn->getType(), false);
718     llvm::FunctionCallee AtExitFunc =
719         CGM.CreateRuntimeFunction(AtExitTy, "atexit", llvm::AttributeList(),
720                                   /*Local=*/true);
721     CtorBuilder.CreateCall(AtExitFunc, CleanupFn);
722   }
723 
724   CtorBuilder.CreateRetVoid();
725   return ModuleCtorFunc;
726 }
727 
728 /// Creates a global destructor function that unregisters the GPU code blob
729 /// registered by constructor.
730 ///
731 /// For CUDA:
732 /// \code
733 /// void __cuda_module_dtor(void*) {
734 ///     __cudaUnregisterFatBinary(Handle);
735 /// }
736 /// \endcode
737 ///
738 /// For HIP:
739 /// \code
740 /// void __hip_module_dtor(void*) {
741 ///     if (__hip_gpubin_handle) {
742 ///         __hipUnregisterFatBinary(__hip_gpubin_handle);
743 ///         __hip_gpubin_handle = 0;
744 ///     }
745 /// }
746 /// \endcode
747 llvm::Function *CGNVCUDARuntime::makeModuleDtorFunction() {
748   // No need for destructor if we don't have a handle to unregister.
749   if (!GpuBinaryHandle)
750     return nullptr;
751 
752   // void __cudaUnregisterFatBinary(void ** handle);
753   llvm::FunctionCallee UnregisterFatbinFunc = CGM.CreateRuntimeFunction(
754       llvm::FunctionType::get(VoidTy, VoidPtrPtrTy, false),
755       addUnderscoredPrefixToName("UnregisterFatBinary"));
756 
757   llvm::Function *ModuleDtorFunc = llvm::Function::Create(
758       llvm::FunctionType::get(VoidTy, VoidPtrTy, false),
759       llvm::GlobalValue::InternalLinkage,
760       addUnderscoredPrefixToName("_module_dtor"), &TheModule);
761 
762   llvm::BasicBlock *DtorEntryBB =
763       llvm::BasicBlock::Create(Context, "entry", ModuleDtorFunc);
764   CGBuilderTy DtorBuilder(CGM, Context);
765   DtorBuilder.SetInsertPoint(DtorEntryBB);
766 
767   Address GpuBinaryAddr(GpuBinaryHandle, CharUnits::fromQuantity(
768                                              GpuBinaryHandle->getAlignment()));
769   auto HandleValue = DtorBuilder.CreateLoad(GpuBinaryAddr);
770   // There is only one HIP fat binary per linked module, however there are
771   // multiple destructor functions. Make sure the fat binary is unregistered
772   // only once.
773   if (CGM.getLangOpts().HIP) {
774     llvm::BasicBlock *IfBlock =
775         llvm::BasicBlock::Create(Context, "if", ModuleDtorFunc);
776     llvm::BasicBlock *ExitBlock =
777         llvm::BasicBlock::Create(Context, "exit", ModuleDtorFunc);
778     llvm::Constant *Zero = llvm::Constant::getNullValue(HandleValue->getType());
779     llvm::Value *NEZero = DtorBuilder.CreateICmpNE(HandleValue, Zero);
780     DtorBuilder.CreateCondBr(NEZero, IfBlock, ExitBlock);
781 
782     DtorBuilder.SetInsertPoint(IfBlock);
783     DtorBuilder.CreateCall(UnregisterFatbinFunc, HandleValue);
784     DtorBuilder.CreateStore(Zero, GpuBinaryAddr);
785     DtorBuilder.CreateBr(ExitBlock);
786 
787     DtorBuilder.SetInsertPoint(ExitBlock);
788   } else {
789     DtorBuilder.CreateCall(UnregisterFatbinFunc, HandleValue);
790   }
791   DtorBuilder.CreateRetVoid();
792   return ModuleDtorFunc;
793 }
794 
795 std::string CGNVCUDARuntime::getDeviceStubName(llvm::StringRef Name) const {
796   if (!CGM.getLangOpts().HIP)
797     return Name;
798   return (Name + ".stub").str();
799 }
800 
801 CGCUDARuntime *CodeGen::CreateNVCUDARuntime(CodeGenModule &CGM) {
802   return new CGNVCUDARuntime(CGM);
803 }
804