1 //===- NVVMReflect.cpp - NVVM Emulate conditional compilation -------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
15 //===----------------------------------------------------------------------===//
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/Transforms/Scalar.h"
38 #define NVVM_REFLECT_FUNCTION "__nvvm_reflect"
42 #define DEBUG_TYPE "nvptx-reflect"
44 namespace llvm { void initializeNVVMReflectPass(PassRegistry &); }
47 class NVVMReflect : public ModulePass {
49 StringMap<int> VarMap;
50 typedef DenseMap<std::string, int>::iterator VarMapIter;
54 NVVMReflect() : ModulePass(ID) {
55 initializeNVVMReflectPass(*PassRegistry::getPassRegistry());
59 NVVMReflect(const StringMap<int> &Mapping)
61 initializeNVVMReflectPass(*PassRegistry::getPassRegistry());
62 for (StringMap<int>::const_iterator I = Mapping.begin(), E = Mapping.end();
64 VarMap[(*I).getKey()] = (*I).getValue();
68 void getAnalysisUsage(AnalysisUsage &AU) const override {
71 bool runOnModule(Module &) override;
74 bool handleFunction(Function *ReflectFunction);
79 ModulePass *llvm::createNVVMReflectPass() {
80 return new NVVMReflect();
83 ModulePass *llvm::createNVVMReflectPass(const StringMap<int>& Mapping) {
84 return new NVVMReflect(Mapping);
88 NVVMReflectEnabled("nvvm-reflect-enable", cl::init(true), cl::Hidden,
89 cl::desc("NVVM reflection, enabled by default"));
91 char NVVMReflect::ID = 0;
92 INITIALIZE_PASS(NVVMReflect, "nvvm-reflect",
93 "Replace occurrences of __nvvm_reflect() calls with 0/1", false,
96 static cl::list<std::string>
97 ReflectList("nvvm-reflect-list", cl::value_desc("name=<int>"), cl::Hidden,
98 cl::desc("A list of string=num assignments"),
101 /// The command line can look as follows :
102 /// -nvvm-reflect-list a=1,b=2 -nvvm-reflect-list c=3,d=0 -R e=2
103 /// The strings "a=1,b=2", "c=3,d=0", "e=2" are available in the
104 /// ReflectList vector. First, each of ReflectList[i] is 'split'
105 /// using "," as the delimiter. Then each of this part is split
106 /// using "=" as the delimiter.
107 void NVVMReflect::setVarMap() {
108 for (unsigned i = 0, e = ReflectList.size(); i != e; ++i) {
109 DEBUG(dbgs() << "Option : " << ReflectList[i] << "\n");
110 SmallVector<StringRef, 4> NameValList;
111 StringRef(ReflectList[i]).split(NameValList, ",");
112 for (unsigned j = 0, ej = NameValList.size(); j != ej; ++j) {
113 SmallVector<StringRef, 2> NameValPair;
114 NameValList[j].split(NameValPair, "=");
115 assert(NameValPair.size() == 2 && "name=val expected");
116 std::stringstream ValStream(NameValPair[1]);
119 assert((!(ValStream.fail())) && "integer value expected");
120 VarMap[NameValPair[0]] = Val;
125 bool NVVMReflect::handleFunction(Function *ReflectFunction) {
126 // Validate _reflect function
127 assert(ReflectFunction->isDeclaration() &&
128 "_reflect function should not have a body");
129 assert(ReflectFunction->getReturnType()->isIntegerTy() &&
130 "_reflect's return type should be integer");
132 std::vector<Instruction *> ToRemove;
134 // Go through the uses of ReflectFunction in this Function.
135 // Each of them should a CallInst with a ConstantArray argument.
136 // First validate that. If the c-string corresponding to the
137 // ConstantArray can be found successfully, see if it can be
138 // found in VarMap. If so, replace the uses of CallInst with the
139 // value found in VarMap. If not, replace the use with value 0.
141 // IR for __nvvm_reflect calls differs between CUDA versions:
142 // CUDA 6.5 and earlier uses this sequence:
143 // %ptr = tail call i8* @llvm.nvvm.ptr.constant.to.gen.p0i8.p4i8
144 // (i8 addrspace(4)* getelementptr inbounds
145 // ([8 x i8], [8 x i8] addrspace(4)* @str, i32 0, i32 0))
146 // %reflect = tail call i32 @__nvvm_reflect(i8* %ptr)
148 // Value returned by Sym->getOperand(0) is a Constant with a
149 // ConstantDataSequential operand which can be converted to string and used
152 // CUDA 7.0 does it slightly differently:
153 // %reflect = call i32 @__nvvm_reflect(i8* addrspacecast
154 // (i8 addrspace(1)* getelementptr inbounds
155 // ([8 x i8], [8 x i8] addrspace(1)* @str, i32 0, i32 0) to i8*))
157 // In this case, we get a Constant with a GlobalVariable operand and we need
158 // to dig deeper to find its initializer with the string we'll use for lookup.
160 for (User *U : ReflectFunction->users()) {
161 assert(isa<CallInst>(U) && "Only a call instruction can use _reflect");
162 CallInst *Reflect = cast<CallInst>(U);
164 assert((Reflect->getNumOperands() == 2) &&
165 "Only one operand expect for _reflect function");
166 // In cuda, we will have an extra constant-to-generic conversion of
168 const Value *Str = Reflect->getArgOperand(0);
169 if (isa<CallInst>(Str)) {
171 const CallInst *ConvCall = cast<CallInst>(Str);
172 Str = ConvCall->getArgOperand(0);
174 assert(isa<ConstantExpr>(Str) &&
175 "Format of _reflect function not recognized");
176 const ConstantExpr *GEP = cast<ConstantExpr>(Str);
178 const Value *Sym = GEP->getOperand(0);
179 assert(isa<Constant>(Sym) && "Format of _reflect function not recognized");
181 const Value *Operand = cast<Constant>(Sym)->getOperand(0);
182 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(Operand)) {
183 // For CUDA-7.0 style __nvvm_reflect calls we need to find operand's
185 assert(GV->hasInitializer() &&
186 "Format of _reflect function not recognized");
187 const Constant *Initializer = GV->getInitializer();
188 Operand = Initializer;
191 assert(isa<ConstantDataSequential>(Operand) &&
192 "Format of _reflect function not recognized");
193 assert(cast<ConstantDataSequential>(Operand)->isCString() &&
194 "Format of _reflect function not recognized");
196 std::string ReflectArg =
197 cast<ConstantDataSequential>(Operand)->getAsString();
199 ReflectArg = ReflectArg.substr(0, ReflectArg.size() - 1);
200 DEBUG(dbgs() << "Arg of _reflect : " << ReflectArg << "\n");
202 int ReflectVal = 0; // The default value is 0
203 if (VarMap.find(ReflectArg) != VarMap.end()) {
204 ReflectVal = VarMap[ReflectArg];
206 Reflect->replaceAllUsesWith(
207 ConstantInt::get(Reflect->getType(), ReflectVal));
208 ToRemove.push_back(Reflect);
210 if (ToRemove.size() == 0)
213 for (unsigned i = 0, e = ToRemove.size(); i != e; ++i)
214 ToRemove[i]->eraseFromParent();
218 bool NVVMReflect::runOnModule(Module &M) {
219 if (!NVVMReflectEnabled)
228 Type *I8Ty = Type::getInt8Ty(M.getContext());
229 Function *ReflectFunction;
231 // Check for standard overloaded versions of llvm.nvvm.reflect
233 for (unsigned i = 0; i != 5; ++i) {
234 Tys[0] = PointerType::get(I8Ty, i);
235 Name = Intrinsic::getName(Intrinsic::nvvm_reflect, Tys);
236 ReflectFunction = M.getFunction(Name);
237 if(ReflectFunction != 0) {
238 Res |= handleFunction(ReflectFunction);
242 ReflectFunction = M.getFunction(NVVM_REFLECT_FUNCTION);
243 // If reflect function is not used, then there will be
244 // no entry in the module.
245 if (ReflectFunction != 0)
246 Res |= handleFunction(ReflectFunction);