1 //===- CloneModule.cpp - Clone an entire module ---------------------------===// 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 file implements the CloneModule interface which makes a copy of an 11 // entire module. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/Transforms/Utils/Cloning.h" 16 #include "llvm/IR/Constant.h" 17 #include "llvm/IR/DerivedTypes.h" 18 #include "llvm/IR/Module.h" 19 #include "llvm/Transforms/Utils/ValueMapper.h" 20 #include "llvm-c/Core.h" 21 using namespace llvm; 22 23 /// This is not as easy as it might seem because we have to worry about making 24 /// copies of global variables and functions, and making their (initializers and 25 /// references, respectively) refer to the right globals. 26 /// 27 std::unique_ptr<Module> llvm::CloneModule(const Module *M) { 28 // Create the value map that maps things from the old module over to the new 29 // module. 30 ValueToValueMapTy VMap; 31 return CloneModule(M, VMap); 32 } 33 34 std::unique_ptr<Module> llvm::CloneModule(const Module *M, 35 ValueToValueMapTy &VMap) { 36 return CloneModule(M, VMap, [](const GlobalValue *GV) { return true; }); 37 } 38 39 std::unique_ptr<Module> llvm::CloneModule( 40 const Module *M, ValueToValueMapTy &VMap, 41 function_ref<bool(const GlobalValue *)> ShouldCloneDefinition) { 42 // First off, we need to create the new module. 43 std::unique_ptr<Module> New = 44 llvm::make_unique<Module>(M->getModuleIdentifier(), M->getContext()); 45 New->setDataLayout(M->getDataLayout()); 46 New->setTargetTriple(M->getTargetTriple()); 47 New->setModuleInlineAsm(M->getModuleInlineAsm()); 48 49 // Loop over all of the global variables, making corresponding globals in the 50 // new module. Here we add them to the VMap and to the new Module. We 51 // don't worry about attributes or initializers, they will come later. 52 // 53 for (Module::const_global_iterator I = M->global_begin(), E = M->global_end(); 54 I != E; ++I) { 55 GlobalVariable *GV = new GlobalVariable(*New, 56 I->getValueType(), 57 I->isConstant(), I->getLinkage(), 58 (Constant*) nullptr, I->getName(), 59 (GlobalVariable*) nullptr, 60 I->getThreadLocalMode(), 61 I->getType()->getAddressSpace()); 62 GV->copyAttributesFrom(&*I); 63 VMap[&*I] = GV; 64 } 65 66 // Loop over the functions in the module, making external functions as before 67 for (const Function &I : *M) { 68 Function *NF = Function::Create(cast<FunctionType>(I.getValueType()), 69 I.getLinkage(), I.getName(), New.get()); 70 NF->copyAttributesFrom(&I); 71 VMap[&I] = NF; 72 } 73 74 // Loop over the aliases in the module 75 for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end(); 76 I != E; ++I) { 77 if (!ShouldCloneDefinition(&*I)) { 78 // An alias cannot act as an external reference, so we need to create 79 // either a function or a global variable depending on the value type. 80 // FIXME: Once pointee types are gone we can probably pick one or the 81 // other. 82 GlobalValue *GV; 83 if (I->getValueType()->isFunctionTy()) 84 GV = Function::Create(cast<FunctionType>(I->getValueType()), 85 GlobalValue::ExternalLinkage, I->getName(), 86 New.get()); 87 else 88 GV = new GlobalVariable( 89 *New, I->getValueType(), false, GlobalValue::ExternalLinkage, 90 (Constant *)nullptr, I->getName(), (GlobalVariable *)nullptr, 91 I->getThreadLocalMode(), I->getType()->getAddressSpace()); 92 VMap[&*I] = GV; 93 // We do not copy attributes (mainly because copying between different 94 // kinds of globals is forbidden), but this is generally not required for 95 // correctness. 96 continue; 97 } 98 auto *GA = GlobalAlias::create(I->getValueType(), 99 I->getType()->getPointerAddressSpace(), 100 I->getLinkage(), I->getName(), New.get()); 101 GA->copyAttributesFrom(&*I); 102 VMap[&*I] = GA; 103 } 104 105 // Now that all of the things that global variable initializer can refer to 106 // have been created, loop through and copy the global variable referrers 107 // over... We also set the attributes on the global now. 108 // 109 for (Module::const_global_iterator I = M->global_begin(), E = M->global_end(); 110 I != E; ++I) { 111 if (I->isDeclaration()) 112 continue; 113 114 GlobalVariable *GV = cast<GlobalVariable>(VMap[&*I]); 115 if (!ShouldCloneDefinition(&*I)) { 116 // Skip after setting the correct linkage for an external reference. 117 GV->setLinkage(GlobalValue::ExternalLinkage); 118 continue; 119 } 120 if (I->hasInitializer()) 121 GV->setInitializer(MapValue(I->getInitializer(), VMap)); 122 } 123 124 // Similarly, copy over function bodies now... 125 // 126 for (const Function &I : *M) { 127 if (I.isDeclaration()) 128 continue; 129 130 Function *F = cast<Function>(VMap[&I]); 131 if (!ShouldCloneDefinition(&I)) { 132 // Skip after setting the correct linkage for an external reference. 133 F->setLinkage(GlobalValue::ExternalLinkage); 134 // Personality function is not valid on a declaration. 135 F->setPersonalityFn(nullptr); 136 continue; 137 } 138 139 Function::arg_iterator DestI = F->arg_begin(); 140 for (Function::const_arg_iterator J = I.arg_begin(); J != I.arg_end(); 141 ++J) { 142 DestI->setName(J->getName()); 143 VMap[&*J] = &*DestI++; 144 } 145 146 SmallVector<ReturnInst *, 8> Returns; // Ignore returns cloned. 147 CloneFunctionInto(F, &I, VMap, /*ModuleLevelChanges=*/true, Returns); 148 149 if (I.hasPersonalityFn()) 150 F->setPersonalityFn(MapValue(I.getPersonalityFn(), VMap)); 151 } 152 153 // And aliases 154 for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end(); 155 I != E; ++I) { 156 // We already dealt with undefined aliases above. 157 if (!ShouldCloneDefinition(&*I)) 158 continue; 159 GlobalAlias *GA = cast<GlobalAlias>(VMap[&*I]); 160 if (const Constant *C = I->getAliasee()) 161 GA->setAliasee(MapValue(C, VMap)); 162 } 163 164 // And named metadata.... 165 for (Module::const_named_metadata_iterator I = M->named_metadata_begin(), 166 E = M->named_metadata_end(); I != E; ++I) { 167 const NamedMDNode &NMD = *I; 168 NamedMDNode *NewNMD = New->getOrInsertNamedMetadata(NMD.getName()); 169 for (unsigned i = 0, e = NMD.getNumOperands(); i != e; ++i) 170 NewNMD->addOperand(MapMetadata(NMD.getOperand(i), VMap)); 171 } 172 173 return New; 174 } 175 176 extern "C" { 177 178 LLVMModuleRef LLVMCloneModule(LLVMModuleRef M) { 179 return wrap(CloneModule(unwrap(M)).release()); 180 } 181 182 } 183