1 //===- CloneModule.cpp - Clone an entire module ---------------------------===//
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 file implements the CloneModule interface which makes a copy of an
10 // entire module.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "llvm-c/Core.h"
15 #include "llvm/IR/DerivedTypes.h"
16 #include "llvm/IR/Module.h"
17 #include "llvm/Transforms/Utils/Cloning.h"
18 #include "llvm/Transforms/Utils/ValueMapper.h"
19 using namespace llvm;
20
21 namespace llvm {
22 class Constant;
23 }
24
copyComdat(GlobalObject * Dst,const GlobalObject * Src)25 static void copyComdat(GlobalObject *Dst, const GlobalObject *Src) {
26 const Comdat *SC = Src->getComdat();
27 if (!SC)
28 return;
29 Comdat *DC = Dst->getParent()->getOrInsertComdat(SC->getName());
30 DC->setSelectionKind(SC->getSelectionKind());
31 Dst->setComdat(DC);
32 }
33
34 /// This is not as easy as it might seem because we have to worry about making
35 /// copies of global variables and functions, and making their (initializers and
36 /// references, respectively) refer to the right globals.
37 ///
38 /// Cloning un-materialized modules is not currently supported, so any
39 /// modules initialized via lazy loading should be materialized before cloning
CloneModule(const Module & M)40 std::unique_ptr<Module> llvm::CloneModule(const Module &M) {
41 // Create the value map that maps things from the old module over to the new
42 // module.
43 ValueToValueMapTy VMap;
44 return CloneModule(M, VMap);
45 }
46
CloneModule(const Module & M,ValueToValueMapTy & VMap)47 std::unique_ptr<Module> llvm::CloneModule(const Module &M,
48 ValueToValueMapTy &VMap) {
49 return CloneModule(M, VMap, [](const GlobalValue *GV) { return true; });
50 }
51
CloneModule(const Module & M,ValueToValueMapTy & VMap,function_ref<bool (const GlobalValue *)> ShouldCloneDefinition)52 std::unique_ptr<Module> llvm::CloneModule(
53 const Module &M, ValueToValueMapTy &VMap,
54 function_ref<bool(const GlobalValue *)> ShouldCloneDefinition) {
55
56 assert(M.isMaterialized() && "Module must be materialized before cloning!");
57
58 // First off, we need to create the new module.
59 std::unique_ptr<Module> New =
60 std::make_unique<Module>(M.getModuleIdentifier(), M.getContext());
61 New->setSourceFileName(M.getSourceFileName());
62 New->setDataLayout(M.getDataLayout());
63 New->setTargetTriple(M.getTargetTriple());
64 New->setModuleInlineAsm(M.getModuleInlineAsm());
65
66 // Loop over all of the global variables, making corresponding globals in the
67 // new module. Here we add them to the VMap and to the new Module. We
68 // don't worry about attributes or initializers, they will come later.
69 //
70 for (const GlobalVariable &I : M.globals()) {
71 GlobalVariable *NewGV = new GlobalVariable(
72 *New, I.getValueType(), I.isConstant(), I.getLinkage(),
73 (Constant *)nullptr, I.getName(), (GlobalVariable *)nullptr,
74 I.getThreadLocalMode(), I.getType()->getAddressSpace());
75 NewGV->copyAttributesFrom(&I);
76 VMap[&I] = NewGV;
77 }
78
79 // Loop over the functions in the module, making external functions as before
80 for (const Function &I : M) {
81 Function *NF =
82 Function::Create(cast<FunctionType>(I.getValueType()), I.getLinkage(),
83 I.getAddressSpace(), I.getName(), New.get());
84 NF->copyAttributesFrom(&I);
85 VMap[&I] = NF;
86 }
87
88 // Loop over the aliases in the module
89 for (const GlobalAlias &I : M.aliases()) {
90 if (!ShouldCloneDefinition(&I)) {
91 // An alias cannot act as an external reference, so we need to create
92 // either a function or a global variable depending on the value type.
93 // FIXME: Once pointee types are gone we can probably pick one or the
94 // other.
95 GlobalValue *GV;
96 if (I.getValueType()->isFunctionTy())
97 GV = Function::Create(cast<FunctionType>(I.getValueType()),
98 GlobalValue::ExternalLinkage, I.getAddressSpace(),
99 I.getName(), New.get());
100 else
101 GV = new GlobalVariable(*New, I.getValueType(), false,
102 GlobalValue::ExternalLinkage, nullptr,
103 I.getName(), nullptr, I.getThreadLocalMode(),
104 I.getType()->getAddressSpace());
105 VMap[&I] = GV;
106 // We do not copy attributes (mainly because copying between different
107 // kinds of globals is forbidden), but this is generally not required for
108 // correctness.
109 continue;
110 }
111 auto *GA = GlobalAlias::create(I.getValueType(),
112 I.getType()->getPointerAddressSpace(),
113 I.getLinkage(), I.getName(), New.get());
114 GA->copyAttributesFrom(&I);
115 VMap[&I] = GA;
116 }
117
118 for (const GlobalIFunc &I : M.ifuncs()) {
119 // Defer setting the resolver function until after functions are cloned.
120 auto *GI =
121 GlobalIFunc::create(I.getValueType(), I.getAddressSpace(),
122 I.getLinkage(), I.getName(), nullptr, New.get());
123 GI->copyAttributesFrom(&I);
124 VMap[&I] = GI;
125 }
126
127 // Similarly, copy over function bodies now...
128 //
129 for (const Function &I : M) {
130 Function *F = cast<Function>(VMap[&I]);
131
132 if (I.isDeclaration()) {
133 // Copy over metadata for declarations since we're not doing it below in
134 // CloneFunctionInto().
135 SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
136 I.getAllMetadata(MDs);
137 for (auto MD : MDs)
138 F->addMetadata(MD.first, *MapMetadata(MD.second, VMap));
139 continue;
140 }
141
142 if (!ShouldCloneDefinition(&I)) {
143 // Skip after setting the correct linkage for an external reference.
144 F->setLinkage(GlobalValue::ExternalLinkage);
145 // Personality function is not valid on a declaration.
146 F->setPersonalityFn(nullptr);
147 continue;
148 }
149
150 Function::arg_iterator DestI = F->arg_begin();
151 for (const Argument &J : I.args()) {
152 DestI->setName(J.getName());
153 VMap[&J] = &*DestI++;
154 }
155
156 SmallVector<ReturnInst *, 8> Returns; // Ignore returns cloned.
157 CloneFunctionInto(F, &I, VMap, CloneFunctionChangeType::ClonedModule,
158 Returns);
159
160 if (I.hasPersonalityFn())
161 F->setPersonalityFn(MapValue(I.getPersonalityFn(), VMap));
162
163 copyComdat(F, &I);
164 }
165
166 // And aliases
167 for (const GlobalAlias &I : M.aliases()) {
168 // We already dealt with undefined aliases above.
169 if (!ShouldCloneDefinition(&I))
170 continue;
171 GlobalAlias *GA = cast<GlobalAlias>(VMap[&I]);
172 if (const Constant *C = I.getAliasee())
173 GA->setAliasee(MapValue(C, VMap));
174 }
175
176 for (const GlobalIFunc &I : M.ifuncs()) {
177 GlobalIFunc *GI = cast<GlobalIFunc>(VMap[&I]);
178 if (const Constant *Resolver = I.getResolver())
179 GI->setResolver(MapValue(Resolver, VMap));
180 }
181
182 // And named metadata....
183 for (const NamedMDNode &NMD : M.named_metadata()) {
184 NamedMDNode *NewNMD = New->getOrInsertNamedMetadata(NMD.getName());
185 for (const MDNode *N : NMD.operands())
186 NewNMD->addOperand(MapMetadata(N, VMap));
187 }
188
189 // Now that all of the things that global variable initializer can refer to
190 // have been created, loop through and copy the global variable referrers
191 // over... We also set the attributes on the global now.
192 //
193 for (const GlobalVariable &G : M.globals()) {
194 GlobalVariable *GV = cast<GlobalVariable>(VMap[&G]);
195
196 SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
197 G.getAllMetadata(MDs);
198 for (auto MD : MDs)
199 GV->addMetadata(MD.first, *MapMetadata(MD.second, VMap));
200
201 if (G.isDeclaration())
202 continue;
203
204 if (!ShouldCloneDefinition(&G)) {
205 // Skip after setting the correct linkage for an external reference.
206 GV->setLinkage(GlobalValue::ExternalLinkage);
207 continue;
208 }
209 if (G.hasInitializer())
210 GV->setInitializer(MapValue(G.getInitializer(), VMap));
211
212 copyComdat(GV, &G);
213 }
214
215 return New;
216 }
217
218 extern "C" {
219
LLVMCloneModule(LLVMModuleRef M)220 LLVMModuleRef LLVMCloneModule(LLVMModuleRef M) {
221 return wrap(CloneModule(*unwrap(M)).release());
222 }
223
224 }
225