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