llvm/lib/Transforms/Utils/CloneModule.cpp

   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"
  18 using namespace llvm;
  19
  20 namespace llvm {
  21 class Constant;
  22 }
  23
  24 static 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
  39 std::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
  46 std::unique_ptr<Module> llvm::CloneModule(const Module &M,
  47                                           ValueToValueMapTy &VMap) {
  48   return CloneModule(M, VMap, [](const GlobalValue *GV) { return true; });
  49 }
  50
  51 std::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
 218 extern "C" {
 219
 220 LLVMModuleRef LLVMCloneModule(LLVMModuleRef M) {
 221   return wrap(CloneModule(*unwrap(M)).release());
 222 }
 223
 224 }