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/IR/ValueHandle.h" 24 #include "llvm/IR/ValueMap.h" 25 #include "llvm/Transforms/Utils/ValueMapper.h" 26 27 namespace llvm { 28 29 class Module; 30 class Function; 31 class Instruction; 32 class Pass; 33 class LPPassManager; 34 class BasicBlock; 35 class Value; 36 class CallInst; 37 class InvokeInst; 38 class ReturnInst; 39 class CallSite; 40 class Trace; 41 class CallGraph; 42 class DataLayout; 43 class Loop; 44 class LoopInfo; 45 class AllocaInst; 46 class AliasAnalysis; 47 class AssumptionCacheTracker; 48 49 /// CloneModule - Return an exact copy of the specified module 50 /// 51 Module *CloneModule(const Module *M); 52 Module *CloneModule(const Module *M, ValueToValueMapTy &VMap); 53 54 /// ClonedCodeInfo - This struct can be used to capture information about code 55 /// being cloned, while it is being cloned. 56 struct ClonedCodeInfo { 57 /// ContainsCalls - This is set to true if the cloned code contains a normal 58 /// call instruction. 59 bool ContainsCalls; 60 61 /// ContainsDynamicAllocas - This is set to true if the cloned code contains 62 /// a 'dynamic' alloca. Dynamic allocas are allocas that are either not in 63 /// the entry block or they are in the entry block but are not a constant 64 /// size. 65 bool ContainsDynamicAllocas; 66 67 ClonedCodeInfo() : ContainsCalls(false), ContainsDynamicAllocas(false) {} 68 }; 69 70 /// CloneBasicBlock - Return a copy of the specified basic block, but without 71 /// embedding the block into a particular function. The block returned is an 72 /// exact copy of the specified basic block, without any remapping having been 73 /// performed. Because of this, this is only suitable for applications where 74 /// the basic block will be inserted into the same function that it was cloned 75 /// from (loop unrolling would use this, for example). 76 /// 77 /// Also, note that this function makes a direct copy of the basic block, and 78 /// can thus produce illegal LLVM code. In particular, it will copy any PHI 79 /// nodes from the original block, even though there are no predecessors for the 80 /// newly cloned block (thus, phi nodes will have to be updated). Also, this 81 /// block will branch to the old successors of the original block: these 82 /// successors will have to have any PHI nodes updated to account for the new 83 /// incoming edges. 84 /// 85 /// The correlation between instructions in the source and result basic blocks 86 /// is recorded in the VMap map. 87 /// 88 /// If you have a particular suffix you'd like to use to add to any cloned 89 /// names, specify it as the optional third parameter. 90 /// 91 /// If you would like the basic block to be auto-inserted into the end of a 92 /// function, you can specify it as the optional fourth parameter. 93 /// 94 /// If you would like to collect additional information about the cloned 95 /// function, you can specify a ClonedCodeInfo object with the optional fifth 96 /// parameter. 97 /// 98 BasicBlock *CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap, 99 const Twine &NameSuffix = "", Function *F = nullptr, 100 ClonedCodeInfo *CodeInfo = nullptr); 101 102 /// CloneFunction - Return a copy of the specified function, but without 103 /// embedding the function into another module. Also, any references specified 104 /// in the VMap are changed to refer to their mapped value instead of the 105 /// original one. If any of the arguments to the function are in the VMap, 106 /// the arguments are deleted from the resultant function. The VMap is 107 /// updated to include mappings from all of the instructions and basicblocks in 108 /// the function from their old to new values. The final argument captures 109 /// information about the cloned code if non-null. 110 /// 111 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue 112 /// mappings, and debug info metadata will not be cloned. 113 /// 114 Function *CloneFunction(const Function *F, ValueToValueMapTy &VMap, 115 bool ModuleLevelChanges, 116 ClonedCodeInfo *CodeInfo = nullptr); 117 118 /// Clone OldFunc into NewFunc, transforming the old arguments into references 119 /// to VMap values. Note that if NewFunc already has basic blocks, the ones 120 /// cloned into it will be added to the end of the function. This function 121 /// fills in a list of return instructions, and can optionally remap types 122 /// and/or append the specified suffix to all values cloned. 123 /// 124 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue 125 /// mappings. 126 /// 127 void CloneFunctionInto(Function *NewFunc, const Function *OldFunc, 128 ValueToValueMapTy &VMap, bool ModuleLevelChanges, 129 SmallVectorImpl<ReturnInst*> &Returns, 130 const char *NameSuffix = "", 131 ClonedCodeInfo *CodeInfo = nullptr, 132 ValueMapTypeRemapper *TypeMapper = nullptr, 133 ValueMaterializer *Materializer = nullptr); 134 135 /// A helper class used with CloneAndPruneIntoFromInst to change the default 136 /// behavior while instructions are being cloned. 137 class CloningDirector { 138 public: 139 /// This enumeration describes the way CloneAndPruneIntoFromInst should 140 /// proceed after the CloningDirector has examined an instruction. 141 enum CloningAction { 142 ///< Continue cloning the instruction (default behavior). 143 CloneInstruction, 144 ///< Skip this instruction but continue cloning the current basic block. 145 SkipInstruction, 146 ///< Skip this instruction and stop cloning the current basic block. 147 StopCloningBB, 148 ///< Don't clone the terminator but clone the current block's successors. 149 CloneSuccessors 150 }; 151 152 virtual ~CloningDirector() {} 153 154 /// Subclasses must override this function to customize cloning behavior. 155 virtual CloningAction handleInstruction(ValueToValueMapTy &VMap, 156 const Instruction *Inst, 157 BasicBlock *NewBB) = 0; 158 159 virtual ValueMapTypeRemapper *getTypeRemapper() { return nullptr; } 160 virtual ValueMaterializer *getValueMaterializer() { return nullptr; } 161 }; 162 163 void CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc, 164 const Instruction *StartingInst, 165 ValueToValueMapTy &VMap, bool ModuleLevelChanges, 166 SmallVectorImpl<ReturnInst*> &Returns, 167 const char *NameSuffix = "", 168 ClonedCodeInfo *CodeInfo = nullptr, 169 CloningDirector *Director = nullptr); 170 171 172 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto, 173 /// except that it does some simple constant prop and DCE on the fly. The 174 /// effect of this is to copy significantly less code in cases where (for 175 /// example) a function call with constant arguments is inlined, and those 176 /// constant arguments cause a significant amount of code in the callee to be 177 /// dead. Since this doesn't produce an exactly copy of the input, it can't be 178 /// used for things like CloneFunction or CloneModule. 179 /// 180 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue 181 /// mappings. 182 /// 183 void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc, 184 ValueToValueMapTy &VMap, bool ModuleLevelChanges, 185 SmallVectorImpl<ReturnInst*> &Returns, 186 const char *NameSuffix = "", 187 ClonedCodeInfo *CodeInfo = nullptr, 188 Instruction *TheCall = nullptr); 189 190 /// InlineFunctionInfo - This class captures the data input to the 191 /// InlineFunction call, and records the auxiliary results produced by it. 192 class InlineFunctionInfo { 193 public: 194 explicit InlineFunctionInfo(CallGraph *cg = nullptr, 195 AliasAnalysis *AA = nullptr, 196 AssumptionCacheTracker *ACT = nullptr) 197 : CG(cg), AA(AA), ACT(ACT) {} 198 199 /// CG - If non-null, InlineFunction will update the callgraph to reflect the 200 /// changes it makes. 201 CallGraph *CG; 202 AliasAnalysis *AA; 203 AssumptionCacheTracker *ACT; 204 205 /// StaticAllocas - InlineFunction fills this in with all static allocas that 206 /// get copied into the caller. 207 SmallVector<AllocaInst *, 4> StaticAllocas; 208 209 /// InlinedCalls - InlineFunction fills this in with callsites that were 210 /// inlined from the callee. This is only filled in if CG is non-null. 211 SmallVector<WeakVH, 8> InlinedCalls; 212 213 void reset() { 214 StaticAllocas.clear(); 215 InlinedCalls.clear(); 216 } 217 }; 218 219 /// InlineFunction - This function inlines the called function into the basic 220 /// block of the caller. This returns false if it is not possible to inline 221 /// this call. The program is still in a well defined state if this occurs 222 /// though. 223 /// 224 /// Note that this only does one level of inlining. For example, if the 225 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now 226 /// exists in the instruction stream. Similarly this will inline a recursive 227 /// function by one level. 228 /// 229 bool InlineFunction(CallInst *C, InlineFunctionInfo &IFI, 230 bool InsertLifetime = true); 231 bool InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI, 232 bool InsertLifetime = true); 233 bool InlineFunction(CallSite CS, InlineFunctionInfo &IFI, 234 bool InsertLifetime = true); 235 236 } // End llvm namespace 237 238 #endif 239
