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/IR/Constant.h"
16 #include "llvm/IR/DerivedTypes.h"
17 #include "llvm/IR/Module.h"
18 #include "llvm/Transforms/Utils/Cloning.h"
19 #include "llvm/Transforms/Utils/ValueMapper.h"
20 using namespace llvm;
21
copyComdat(GlobalObject * Dst,const GlobalObject * Src)22 static void copyComdat(GlobalObject *Dst, const GlobalObject *Src) {
23 const Comdat *SC = Src->getComdat();
24 if (!SC)
25 return;
26 Comdat *DC = Dst->getParent()->getOrInsertComdat(SC->getName());
27 DC->setSelectionKind(SC->getSelectionKind());
28 Dst->setComdat(DC);
29 }
30
31 /// This is not as easy as it might seem because we have to worry about making
32 /// copies of global variables and functions, and making their (initializers and
33 /// references, respectively) refer to the right globals.
34 ///
CloneModule(const Module & M)35 std::unique_ptr<Module> llvm::CloneModule(const Module &M) {
36 // Create the value map that maps things from the old module over to the new
37 // module.
38 ValueToValueMapTy VMap;
39 return CloneModule(M, VMap);
40 }
41
CloneModule(const Module & M,ValueToValueMapTy & VMap)42 std::unique_ptr<Module> llvm::CloneModule(const Module &M,
43 ValueToValueMapTy &VMap) {
44 return CloneModule(M, VMap, [](const GlobalValue *GV) { return true; });
45 }
46
CloneModule(const Module & M,ValueToValueMapTy & VMap,function_ref<bool (const GlobalValue *)> ShouldCloneDefinition)47 std::unique_ptr<Module> llvm::CloneModule(
48 const Module &M, ValueToValueMapTy &VMap,
49 function_ref<bool(const GlobalValue *)> ShouldCloneDefinition) {
50 // First off, we need to create the new module.
51 std::unique_ptr<Module> New =
52 llvm::make_unique<Module>(M.getModuleIdentifier(), M.getContext());
53 New->setSourceFileName(M.getSourceFileName());
54 New->setDataLayout(M.getDataLayout());
55 New->setTargetTriple(M.getTargetTriple());
56 New->setModuleInlineAsm(M.getModuleInlineAsm());
57
58 // Loop over all of the global variables, making corresponding globals in the
59 // new module. Here we add them to the VMap and to the new Module. We
60 // don't worry about attributes or initializers, they will come later.
61 //
62 for (Module::const_global_iterator I = M.global_begin(), E = M.global_end();
63 I != E; ++I) {
64 GlobalVariable *GV = new GlobalVariable(*New,
65 I->getValueType(),
66 I->isConstant(), I->getLinkage(),
67 (Constant*) nullptr, I->getName(),
68 (GlobalVariable*) nullptr,
69 I->getThreadLocalMode(),
70 I->getType()->getAddressSpace());
71 GV->copyAttributesFrom(&*I);
72 VMap[&*I] = GV;
73 }
74
75 // Loop over the functions in the module, making external functions as before
76 for (const Function &I : M) {
77 Function *NF = Function::Create(cast<FunctionType>(I.getValueType()),
78 I.getLinkage(), I.getName(), New.get());
79 NF->copyAttributesFrom(&I);
80 VMap[&I] = NF;
81 }
82
83 // Loop over the aliases in the module
84 for (Module::const_alias_iterator I = M.alias_begin(), E = M.alias_end();
85 I != E; ++I) {
86 if (!ShouldCloneDefinition(&*I)) {
87 // An alias cannot act as an external reference, so we need to create
88 // either a function or a global variable depending on the value type.
89 // FIXME: Once pointee types are gone we can probably pick one or the
90 // other.
91 GlobalValue *GV;
92 if (I->getValueType()->isFunctionTy())
93 GV = Function::Create(cast<FunctionType>(I->getValueType()),
94 GlobalValue::ExternalLinkage, I->getName(),
95 New.get());
96 else
97 GV = new GlobalVariable(
98 *New, I->getValueType(), false, GlobalValue::ExternalLinkage,
99 nullptr, I->getName(), nullptr,
100 I->getThreadLocalMode(), I->getType()->getAddressSpace());
101 VMap[&*I] = GV;
102 // We do not copy attributes (mainly because copying between different
103 // kinds of globals is forbidden), but this is generally not required for
104 // correctness.
105 continue;
106 }
107 auto *GA = GlobalAlias::create(I->getValueType(),
108 I->getType()->getPointerAddressSpace(),
109 I->getLinkage(), I->getName(), New.get());
110 GA->copyAttributesFrom(&*I);
111 VMap[&*I] = GA;
112 }
113
114 // Now that all of the things that global variable initializer can refer to
115 // have been created, loop through and copy the global variable referrers
116 // over... We also set the attributes on the global now.
117 //
118 for (Module::const_global_iterator I = M.global_begin(), E = M.global_end();
119 I != E; ++I) {
120 if (I->isDeclaration())
121 continue;
122
123 GlobalVariable *GV = cast<GlobalVariable>(VMap[&*I]);
124 if (!ShouldCloneDefinition(&*I)) {
125 // Skip after setting the correct linkage for an external reference.
126 GV->setLinkage(GlobalValue::ExternalLinkage);
127 continue;
128 }
129 if (I->hasInitializer())
130 GV->setInitializer(MapValue(I->getInitializer(), VMap));
131
132 SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
133 I->getAllMetadata(MDs);
134 for (auto MD : MDs)
135 GV->addMetadata(MD.first,
136 *MapMetadata(MD.second, VMap, RF_MoveDistinctMDs));
137
138 copyComdat(GV, &*I);
139 }
140
141 // Similarly, copy over function bodies now...
142 //
143 for (const Function &I : M) {
144 if (I.isDeclaration())
145 continue;
146
147 Function *F = cast<Function>(VMap[&I]);
148 if (!ShouldCloneDefinition(&I)) {
149 // Skip after setting the correct linkage for an external reference.
150 F->setLinkage(GlobalValue::ExternalLinkage);
151 // Personality function is not valid on a declaration.
152 F->setPersonalityFn(nullptr);
153 continue;
154 }
155
156 Function::arg_iterator DestI = F->arg_begin();
157 for (Function::const_arg_iterator J = I.arg_begin(); J != I.arg_end();
158 ++J) {
159 DestI->setName(J->getName());
160 VMap[&*J] = &*DestI++;
161 }
162
163 SmallVector<ReturnInst *, 8> Returns; // Ignore returns cloned.
164 CloneFunctionInto(F, &I, VMap, /*ModuleLevelChanges=*/true, Returns);
165
166 if (I.hasPersonalityFn())
167 F->setPersonalityFn(MapValue(I.getPersonalityFn(), VMap));
168
169 copyComdat(F, &I);
170 }
171
172 // And aliases
173 for (Module::const_alias_iterator I = M.alias_begin(), E = M.alias_end();
174 I != E; ++I) {
175 // We already dealt with undefined aliases above.
176 if (!ShouldCloneDefinition(&*I))
177 continue;
178 GlobalAlias *GA = cast<GlobalAlias>(VMap[&*I]);
179 if (const Constant *C = I->getAliasee())
180 GA->setAliasee(MapValue(C, VMap));
181 }
182
183 // And named metadata....
184 for (Module::const_named_metadata_iterator I = M.named_metadata_begin(),
185 E = M.named_metadata_end();
186 I != E; ++I) {
187 const NamedMDNode &NMD = *I;
188 NamedMDNode *NewNMD = New->getOrInsertNamedMetadata(NMD.getName());
189 for (unsigned i = 0, e = NMD.getNumOperands(); i != e; ++i)
190 NewNMD->addOperand(MapMetadata(NMD.getOperand(i), VMap));
191 }
192
193 return New;
194 }
195
196 extern "C" {
197
LLVMCloneModule(LLVMModuleRef M)198 LLVMModuleRef LLVMCloneModule(LLVMModuleRef M) {
199 return wrap(CloneModule(*unwrap(M)).release());
200 }
201
202 }
203