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(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, [](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>(M.getModuleIdentifier(), M.getContext());
60  New->setSourceFileName(M.getSourceFileName());
61  New->setDataLayout(M.getDataLayout());
62  New->setTargetTriple(M.getTargetTriple());
63  New->setModuleInlineAsm(M.getModuleInlineAsm());
64  New->IsNewDbgInfoFormat = M.IsNewDbgInfoFormat;
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  // Now that all of the things that global variable initializer can refer to
128  // have been created, loop through and copy the global variable referrers
129  // over...  We also set the attributes on the global now.
130  //
131  for (const GlobalVariable &G : M.globals()) {
132    GlobalVariable *GV = cast<GlobalVariable>(VMap[&G]);
133
134    SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
135    G.getAllMetadata(MDs);
136    for (auto MD : MDs)
137      GV->addMetadata(MD.first, *MapMetadata(MD.second, VMap));
138
139    if (G.isDeclaration())
140      continue;
141
142    if (!ShouldCloneDefinition(&G)) {
143      // Skip after setting the correct linkage for an external reference.
144      GV->setLinkage(GlobalValue::ExternalLinkage);
145      continue;
146    }
147    if (G.hasInitializer())
148      GV->setInitializer(MapValue(G.getInitializer(), VMap));
149
150    copyComdat(GV, &G);
151  }
152
153  // Similarly, copy over function bodies now...
154  //
155  for (const Function &I : M) {
156    Function *F = cast<Function>(VMap[&I]);
157
158    if (I.isDeclaration()) {
159      // Copy over metadata for declarations since we're not doing it below in
160      // CloneFunctionInto().
161      SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
162      I.getAllMetadata(MDs);
163      for (auto MD : MDs)
164        F->addMetadata(MD.first, *MapMetadata(MD.second, VMap));
165      continue;
166    }
167
168    if (!ShouldCloneDefinition(&I)) {
169      // Skip after setting the correct linkage for an external reference.
170      F->setLinkage(GlobalValue::ExternalLinkage);
171      // Personality function is not valid on a declaration.
172      F->setPersonalityFn(nullptr);
173      continue;
174    }
175
176    Function::arg_iterator DestI = F->arg_begin();
177    for (const Argument &J : I.args()) {
178      DestI->setName(J.getName());
179      VMap[&J] = &*DestI++;
180    }
181
182    SmallVector<ReturnInst *, 8> Returns; // Ignore returns cloned.
183    CloneFunctionInto(F, &I, VMap, CloneFunctionChangeType::ClonedModule,
184                      Returns);
185
186    if (I.hasPersonalityFn())
187      F->setPersonalityFn(MapValue(I.getPersonalityFn(), VMap));
188
189    copyComdat(F, &I);
190  }
191
192  // And aliases
193  for (const GlobalAlias &I : M.aliases()) {
194    // We already dealt with undefined aliases above.
195    if (!ShouldCloneDefinition(&I))
196      continue;
197    GlobalAlias *GA = cast<GlobalAlias>(VMap[&I]);
198    if (const Constant *C = I.getAliasee())
199      GA->setAliasee(MapValue(C, VMap));
200  }
201
202  for (const GlobalIFunc &I : M.ifuncs()) {
203    GlobalIFunc *GI = cast<GlobalIFunc>(VMap[&I]);
204    if (const Constant *Resolver = I.getResolver())
205      GI->setResolver(MapValue(Resolver, VMap));
206  }
207
208  // And named metadata....
209  for (const NamedMDNode &NMD : M.named_metadata()) {
210    NamedMDNode *NewNMD = New->getOrInsertNamedMetadata(NMD.getName());
211    for (unsigned i = 0, e = NMD.getNumOperands(); i != e; ++i)
212      NewNMD->addOperand(MapMetadata(NMD.getOperand(i), VMap));
213  }
214
215  return New;
216}
217
218extern "C" {
219
220LLVMModuleRef LLVMCloneModule(LLVMModuleRef M) {
221  return wrap(CloneModule(*unwrap(M)).release());
222}
223
224}
225