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"
21using 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///
27std::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
34std::unique_ptr<Module> llvm::CloneModule(const Module *M,
35                                          ValueToValueMapTy &VMap) {
36  return CloneModule(M, VMap, [](const GlobalValue *GV) { return true; });
37}
38
39std::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
176extern "C" {
177
178LLVMModuleRef LLVMCloneModule(LLVMModuleRef M) {
179  return wrap(CloneModule(unwrap(M)).release());
180}
181
182}
183