1 //===- NVVMReflect.cpp - NVVM Emulate conditional compilation -------------===// 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 pass replaces occurrences of __nvvm_reflect("string") with an 11 // integer based on -nvvm-reflect-list string=<int> option given to this pass. 12 // If an undefined string value is seen in a call to __nvvm_reflect("string"), 13 // a default value of 0 will be used. 14 // 15 //===----------------------------------------------------------------------===// 16 17 #include "NVPTX.h" 18 #include "llvm/ADT/DenseMap.h" 19 #include "llvm/ADT/SmallVector.h" 20 #include "llvm/ADT/StringMap.h" 21 #include "llvm/IR/Constants.h" 22 #include "llvm/IR/DerivedTypes.h" 23 #include "llvm/IR/Function.h" 24 #include "llvm/IR/Instructions.h" 25 #include "llvm/IR/Intrinsics.h" 26 #include "llvm/IR/Module.h" 27 #include "llvm/IR/Type.h" 28 #include "llvm/Pass.h" 29 #include "llvm/Support/CommandLine.h" 30 #include "llvm/Support/Debug.h" 31 #include "llvm/Support/raw_os_ostream.h" 32 #include "llvm/Support/raw_ostream.h" 33 #include "llvm/Transforms/Scalar.h" 34 #include <map> 35 #include <sstream> 36 #include <string> 37 #include <vector> 38 39 #define NVVM_REFLECT_FUNCTION "__nvvm_reflect" 40 41 using namespace llvm; 42 43 #define DEBUG_TYPE "nvptx-reflect" 44 45 namespace llvm { void initializeNVVMReflectPass(PassRegistry &); } 46 47 namespace { 48 class NVVMReflect : public ModulePass { 49 private: 50 StringMap<int> VarMap; 51 typedef DenseMap<std::string, int>::iterator VarMapIter; 52 53 public: 54 static char ID; 55 NVVMReflect() : ModulePass(ID) { 56 initializeNVVMReflectPass(*PassRegistry::getPassRegistry()); 57 VarMap.clear(); 58 } 59 60 NVVMReflect(const StringMap<int> &Mapping) 61 : ModulePass(ID) { 62 initializeNVVMReflectPass(*PassRegistry::getPassRegistry()); 63 for (StringMap<int>::const_iterator I = Mapping.begin(), E = Mapping.end(); 64 I != E; ++I) { 65 VarMap[(*I).getKey()] = (*I).getValue(); 66 } 67 } 68 69 void getAnalysisUsage(AnalysisUsage &AU) const override { 70 AU.setPreservesAll(); 71 } 72 bool runOnModule(Module &) override; 73 74 private: 75 bool handleFunction(Function *ReflectFunction); 76 void setVarMap(); 77 }; 78 } 79 80 ModulePass *llvm::createNVVMReflectPass() { 81 return new NVVMReflect(); 82 } 83 84 ModulePass *llvm::createNVVMReflectPass(const StringMap<int>& Mapping) { 85 return new NVVMReflect(Mapping); 86 } 87 88 static cl::opt<bool> 89 NVVMReflectEnabled("nvvm-reflect-enable", cl::init(true), cl::Hidden, 90 cl::desc("NVVM reflection, enabled by default")); 91 92 char NVVMReflect::ID = 0; 93 INITIALIZE_PASS(NVVMReflect, "nvvm-reflect", 94 "Replace occurrences of __nvvm_reflect() calls with 0/1", false, 95 false) 96 97 static cl::list<std::string> 98 ReflectList("nvvm-reflect-list", cl::value_desc("name=<int>"), cl::Hidden, 99 cl::desc("A list of string=num assignments"), 100 cl::ValueRequired); 101 102 /// The command line can look as follows : 103 /// -nvvm-reflect-list a=1,b=2 -nvvm-reflect-list c=3,d=0 -R e=2 104 /// The strings "a=1,b=2", "c=3,d=0", "e=2" are available in the 105 /// ReflectList vector. First, each of ReflectList[i] is 'split' 106 /// using "," as the delimiter. Then each of this part is split 107 /// using "=" as the delimiter. 108 void NVVMReflect::setVarMap() { 109 for (unsigned i = 0, e = ReflectList.size(); i != e; ++i) { 110 DEBUG(dbgs() << "Option : " << ReflectList[i] << "\n"); 111 SmallVector<StringRef, 4> NameValList; 112 StringRef(ReflectList[i]).split(NameValList, ','); 113 for (unsigned j = 0, ej = NameValList.size(); j != ej; ++j) { 114 SmallVector<StringRef, 2> NameValPair; 115 NameValList[j].split(NameValPair, '='); 116 assert(NameValPair.size() == 2 && "name=val expected"); 117 std::stringstream ValStream(NameValPair[1]); 118 int Val; 119 ValStream >> Val; 120 assert((!(ValStream.fail())) && "integer value expected"); 121 VarMap[NameValPair[0]] = Val; 122 } 123 } 124 } 125 126 bool NVVMReflect::handleFunction(Function *ReflectFunction) { 127 // Validate _reflect function 128 assert(ReflectFunction->isDeclaration() && 129 "_reflect function should not have a body"); 130 assert(ReflectFunction->getReturnType()->isIntegerTy() && 131 "_reflect's return type should be integer"); 132 133 std::vector<Instruction *> ToRemove; 134 135 // Go through the uses of ReflectFunction in this Function. 136 // Each of them should a CallInst with a ConstantArray argument. 137 // First validate that. If the c-string corresponding to the 138 // ConstantArray can be found successfully, see if it can be 139 // found in VarMap. If so, replace the uses of CallInst with the 140 // value found in VarMap. If not, replace the use with value 0. 141 142 // IR for __nvvm_reflect calls differs between CUDA versions: 143 // CUDA 6.5 and earlier uses this sequence: 144 // %ptr = tail call i8* @llvm.nvvm.ptr.constant.to.gen.p0i8.p4i8 145 // (i8 addrspace(4)* getelementptr inbounds 146 // ([8 x i8], [8 x i8] addrspace(4)* @str, i32 0, i32 0)) 147 // %reflect = tail call i32 @__nvvm_reflect(i8* %ptr) 148 // 149 // Value returned by Sym->getOperand(0) is a Constant with a 150 // ConstantDataSequential operand which can be converted to string and used 151 // for lookup. 152 // 153 // CUDA 7.0 does it slightly differently: 154 // %reflect = call i32 @__nvvm_reflect(i8* addrspacecast 155 // (i8 addrspace(1)* getelementptr inbounds 156 // ([8 x i8], [8 x i8] addrspace(1)* @str, i32 0, i32 0) to i8*)) 157 // 158 // In this case, we get a Constant with a GlobalVariable operand and we need 159 // to dig deeper to find its initializer with the string we'll use for lookup. 160 161 for (User *U : ReflectFunction->users()) { 162 assert(isa<CallInst>(U) && "Only a call instruction can use _reflect"); 163 CallInst *Reflect = cast<CallInst>(U); 164 165 assert((Reflect->getNumOperands() == 2) && 166 "Only one operand expect for _reflect function"); 167 // In cuda, we will have an extra constant-to-generic conversion of 168 // the string. 169 const Value *Str = Reflect->getArgOperand(0); 170 if (isa<CallInst>(Str)) { 171 // CUDA path 172 const CallInst *ConvCall = cast<CallInst>(Str); 173 Str = ConvCall->getArgOperand(0); 174 } 175 assert(isa<ConstantExpr>(Str) && 176 "Format of _reflect function not recognized"); 177 const ConstantExpr *GEP = cast<ConstantExpr>(Str); 178 179 const Value *Sym = GEP->getOperand(0); 180 assert(isa<Constant>(Sym) && "Format of _reflect function not recognized"); 181 182 const Value *Operand = cast<Constant>(Sym)->getOperand(0); 183 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(Operand)) { 184 // For CUDA-7.0 style __nvvm_reflect calls we need to find operand's 185 // initializer. 186 assert(GV->hasInitializer() && 187 "Format of _reflect function not recognized"); 188 const Constant *Initializer = GV->getInitializer(); 189 Operand = Initializer; 190 } 191 192 assert(isa<ConstantDataSequential>(Operand) && 193 "Format of _reflect function not recognized"); 194 assert(cast<ConstantDataSequential>(Operand)->isCString() && 195 "Format of _reflect function not recognized"); 196 197 std::string ReflectArg = 198 cast<ConstantDataSequential>(Operand)->getAsString(); 199 200 ReflectArg = ReflectArg.substr(0, ReflectArg.size() - 1); 201 DEBUG(dbgs() << "Arg of _reflect : " << ReflectArg << "\n"); 202 203 int ReflectVal = 0; // The default value is 0 204 if (VarMap.find(ReflectArg) != VarMap.end()) { 205 ReflectVal = VarMap[ReflectArg]; 206 } 207 Reflect->replaceAllUsesWith( 208 ConstantInt::get(Reflect->getType(), ReflectVal)); 209 ToRemove.push_back(Reflect); 210 } 211 if (ToRemove.size() == 0) 212 return false; 213 214 for (unsigned i = 0, e = ToRemove.size(); i != e; ++i) 215 ToRemove[i]->eraseFromParent(); 216 return true; 217 } 218 219 bool NVVMReflect::runOnModule(Module &M) { 220 if (!NVVMReflectEnabled) 221 return false; 222 223 setVarMap(); 224 225 226 bool Res = false; 227 std::string Name; 228 Type *Tys[1]; 229 Type *I8Ty = Type::getInt8Ty(M.getContext()); 230 Function *ReflectFunction; 231 232 // Check for standard overloaded versions of llvm.nvvm.reflect 233 234 for (unsigned i = 0; i != 5; ++i) { 235 Tys[0] = PointerType::get(I8Ty, i); 236 Name = Intrinsic::getName(Intrinsic::nvvm_reflect, Tys); 237 ReflectFunction = M.getFunction(Name); 238 if(ReflectFunction != 0) { 239 Res |= handleFunction(ReflectFunction); 240 } 241 } 242 243 ReflectFunction = M.getFunction(NVVM_REFLECT_FUNCTION); 244 // If reflect function is not used, then there will be 245 // no entry in the module. 246 if (ReflectFunction != 0) 247 Res |= handleFunction(ReflectFunction); 248 249 return Res; 250 } 251
