1 //===- Cloning.h - Clone various parts of LLVM programs ---------*- C++ -*-===// 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 defines various functions that are used to clone chunks of LLVM 11 // code for various purposes. This varies from copying whole modules into new 12 // modules, to cloning functions with different arguments, to inlining 13 // functions, to copying basic blocks to support loop unrolling or superblock 14 // formation, etc. 15 // 16 //===----------------------------------------------------------------------===// 17 18 #ifndef LLVM_TRANSFORMS_UTILS_CLONING_H 19 #define LLVM_TRANSFORMS_UTILS_CLONING_H 20 21 #include "llvm/ADT/SmallVector.h" 22 #include "llvm/ADT/Twine.h" 23 #include "llvm/Analysis/AliasAnalysis.h" 24 #include "llvm/IR/ValueHandle.h" 25 #include "llvm/IR/ValueMap.h" 26 #include "llvm/Transforms/Utils/ValueMapper.h" 27 #include <functional> 28 29 namespace llvm { 30 31 class Module; 32 class Function; 33 class Instruction; 34 class Pass; 35 class LPPassManager; 36 class BasicBlock; 37 class Value; 38 class CallInst; 39 class InvokeInst; 40 class ReturnInst; 41 class CallSite; 42 class Trace; 43 class CallGraph; 44 class DataLayout; 45 class Loop; 46 class LoopInfo; 47 class AllocaInst; 48 class AssumptionCacheTracker; 49 class DominatorTree; 50 51 /// Return an exact copy of the specified module 52 /// 53 std::unique_ptr<Module> CloneModule(const Module *M); 54 std::unique_ptr<Module> CloneModule(const Module *M, ValueToValueMapTy &VMap); 55 56 /// Return a copy of the specified module. The ShouldCloneDefinition function 57 /// controls whether a specific GlobalValue's definition is cloned. If the 58 /// function returns false, the module copy will contain an external reference 59 /// in place of the global definition. 60 std::unique_ptr<Module> 61 CloneModule(const Module *M, ValueToValueMapTy &VMap, 62 std::function<bool(const GlobalValue *)> ShouldCloneDefinition); 63 64 /// ClonedCodeInfo - This struct can be used to capture information about code 65 /// being cloned, while it is being cloned. 66 struct ClonedCodeInfo { 67 /// ContainsCalls - This is set to true if the cloned code contains a normal 68 /// call instruction. 69 bool ContainsCalls; 70 71 /// ContainsDynamicAllocas - This is set to true if the cloned code contains 72 /// a 'dynamic' alloca. Dynamic allocas are allocas that are either not in 73 /// the entry block or they are in the entry block but are not a constant 74 /// size. 75 bool ContainsDynamicAllocas; 76 77 /// All cloned call sites that have operand bundles attached are appended to 78 /// this vector. This vector may contain nulls or undefs if some of the 79 /// originally inserted callsites were DCE'ed after they were cloned. 80 std::vector<WeakVH> OperandBundleCallSites; 81 ClonedCodeInfoClonedCodeInfo82 ClonedCodeInfo() : ContainsCalls(false), ContainsDynamicAllocas(false) {} 83 }; 84 85 /// CloneBasicBlock - Return a copy of the specified basic block, but without 86 /// embedding the block into a particular function. The block returned is an 87 /// exact copy of the specified basic block, without any remapping having been 88 /// performed. Because of this, this is only suitable for applications where 89 /// the basic block will be inserted into the same function that it was cloned 90 /// from (loop unrolling would use this, for example). 91 /// 92 /// Also, note that this function makes a direct copy of the basic block, and 93 /// can thus produce illegal LLVM code. In particular, it will copy any PHI 94 /// nodes from the original block, even though there are no predecessors for the 95 /// newly cloned block (thus, phi nodes will have to be updated). Also, this 96 /// block will branch to the old successors of the original block: these 97 /// successors will have to have any PHI nodes updated to account for the new 98 /// incoming edges. 99 /// 100 /// The correlation between instructions in the source and result basic blocks 101 /// is recorded in the VMap map. 102 /// 103 /// If you have a particular suffix you'd like to use to add to any cloned 104 /// names, specify it as the optional third parameter. 105 /// 106 /// If you would like the basic block to be auto-inserted into the end of a 107 /// function, you can specify it as the optional fourth parameter. 108 /// 109 /// If you would like to collect additional information about the cloned 110 /// function, you can specify a ClonedCodeInfo object with the optional fifth 111 /// parameter. 112 /// 113 BasicBlock *CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap, 114 const Twine &NameSuffix = "", Function *F = nullptr, 115 ClonedCodeInfo *CodeInfo = nullptr); 116 117 /// CloneFunction - Return a copy of the specified function, but without 118 /// embedding the function into another module. Also, any references specified 119 /// in the VMap are changed to refer to their mapped value instead of the 120 /// original one. If any of the arguments to the function are in the VMap, 121 /// the arguments are deleted from the resultant function. The VMap is 122 /// updated to include mappings from all of the instructions and basicblocks in 123 /// the function from their old to new values. The final argument captures 124 /// information about the cloned code if non-null. 125 /// 126 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue 127 /// mappings, and debug info metadata will not be cloned. 128 /// 129 Function *CloneFunction(const Function *F, ValueToValueMapTy &VMap, 130 bool ModuleLevelChanges, 131 ClonedCodeInfo *CodeInfo = nullptr); 132 133 /// Clone OldFunc into NewFunc, transforming the old arguments into references 134 /// to VMap values. Note that if NewFunc already has basic blocks, the ones 135 /// cloned into it will be added to the end of the function. This function 136 /// fills in a list of return instructions, and can optionally remap types 137 /// and/or append the specified suffix to all values cloned. 138 /// 139 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue 140 /// mappings. 141 /// 142 void CloneFunctionInto(Function *NewFunc, const Function *OldFunc, 143 ValueToValueMapTy &VMap, bool ModuleLevelChanges, 144 SmallVectorImpl<ReturnInst*> &Returns, 145 const char *NameSuffix = "", 146 ClonedCodeInfo *CodeInfo = nullptr, 147 ValueMapTypeRemapper *TypeMapper = nullptr, 148 ValueMaterializer *Materializer = nullptr); 149 150 /// A helper class used with CloneAndPruneIntoFromInst to change the default 151 /// behavior while instructions are being cloned. 152 class CloningDirector { 153 public: 154 /// This enumeration describes the way CloneAndPruneIntoFromInst should 155 /// proceed after the CloningDirector has examined an instruction. 156 enum CloningAction { 157 ///< Continue cloning the instruction (default behavior). 158 CloneInstruction, 159 ///< Skip this instruction but continue cloning the current basic block. 160 SkipInstruction, 161 ///< Skip this instruction and stop cloning the current basic block. 162 StopCloningBB, 163 ///< Don't clone the terminator but clone the current block's successors. 164 CloneSuccessors 165 }; 166 ~CloningDirector()167 virtual ~CloningDirector() {} 168 169 /// Subclasses must override this function to customize cloning behavior. 170 virtual CloningAction handleInstruction(ValueToValueMapTy &VMap, 171 const Instruction *Inst, 172 BasicBlock *NewBB) = 0; 173 getTypeRemapper()174 virtual ValueMapTypeRemapper *getTypeRemapper() { return nullptr; } getValueMaterializer()175 virtual ValueMaterializer *getValueMaterializer() { return nullptr; } 176 }; 177 178 void CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc, 179 const Instruction *StartingInst, 180 ValueToValueMapTy &VMap, bool ModuleLevelChanges, 181 SmallVectorImpl<ReturnInst*> &Returns, 182 const char *NameSuffix = "", 183 ClonedCodeInfo *CodeInfo = nullptr, 184 CloningDirector *Director = nullptr); 185 186 187 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto, 188 /// except that it does some simple constant prop and DCE on the fly. The 189 /// effect of this is to copy significantly less code in cases where (for 190 /// example) a function call with constant arguments is inlined, and those 191 /// constant arguments cause a significant amount of code in the callee to be 192 /// dead. Since this doesn't produce an exactly copy of the input, it can't be 193 /// used for things like CloneFunction or CloneModule. 194 /// 195 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue 196 /// mappings. 197 /// 198 void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc, 199 ValueToValueMapTy &VMap, bool ModuleLevelChanges, 200 SmallVectorImpl<ReturnInst*> &Returns, 201 const char *NameSuffix = "", 202 ClonedCodeInfo *CodeInfo = nullptr, 203 Instruction *TheCall = nullptr); 204 205 /// InlineFunctionInfo - This class captures the data input to the 206 /// InlineFunction call, and records the auxiliary results produced by it. 207 class InlineFunctionInfo { 208 public: 209 explicit InlineFunctionInfo(CallGraph *cg = nullptr, 210 AssumptionCacheTracker *ACT = nullptr) CG(cg)211 : CG(cg), ACT(ACT) {} 212 213 /// CG - If non-null, InlineFunction will update the callgraph to reflect the 214 /// changes it makes. 215 CallGraph *CG; 216 AssumptionCacheTracker *ACT; 217 218 /// StaticAllocas - InlineFunction fills this in with all static allocas that 219 /// get copied into the caller. 220 SmallVector<AllocaInst *, 4> StaticAllocas; 221 222 /// InlinedCalls - InlineFunction fills this in with callsites that were 223 /// inlined from the callee. This is only filled in if CG is non-null. 224 SmallVector<WeakVH, 8> InlinedCalls; 225 reset()226 void reset() { 227 StaticAllocas.clear(); 228 InlinedCalls.clear(); 229 } 230 }; 231 232 /// InlineFunction - This function inlines the called function into the basic 233 /// block of the caller. This returns false if it is not possible to inline 234 /// this call. The program is still in a well defined state if this occurs 235 /// though. 236 /// 237 /// Note that this only does one level of inlining. For example, if the 238 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now 239 /// exists in the instruction stream. Similarly this will inline a recursive 240 /// function by one level. 241 /// 242 bool InlineFunction(CallInst *C, InlineFunctionInfo &IFI, 243 AAResults *CalleeAAR = nullptr, bool InsertLifetime = true); 244 bool InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI, 245 AAResults *CalleeAAR = nullptr, bool InsertLifetime = true); 246 bool InlineFunction(CallSite CS, InlineFunctionInfo &IFI, 247 AAResults *CalleeAAR = nullptr, bool InsertLifetime = true); 248 249 /// \brief Clones a loop \p OrigLoop. Returns the loop and the blocks in \p 250 /// Blocks. 251 /// 252 /// Updates LoopInfo and DominatorTree assuming the loop is dominated by block 253 /// \p LoopDomBB. Insert the new blocks before block specified in \p Before. 254 Loop *cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB, 255 Loop *OrigLoop, ValueToValueMapTy &VMap, 256 const Twine &NameSuffix, LoopInfo *LI, 257 DominatorTree *DT, 258 SmallVectorImpl<BasicBlock *> &Blocks); 259 260 /// \brief Remaps instructions in \p Blocks using the mapping in \p VMap. 261 void remapInstructionsInBlocks(const SmallVectorImpl<BasicBlock *> &Blocks, 262 ValueToValueMapTy &VMap); 263 264 } // End llvm namespace 265 266 #endif 267