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 class DominatorTree; 49 50 /// CloneModule - Return an exact copy of the specified module 51 /// 52 Module *CloneModule(const Module *M); 53 Module *CloneModule(const Module *M, ValueToValueMapTy &VMap); 54 55 /// ClonedCodeInfo - This struct can be used to capture information about code 56 /// being cloned, while it is being cloned. 57 struct ClonedCodeInfo { 58 /// ContainsCalls - This is set to true if the cloned code contains a normal 59 /// call instruction. 60 bool ContainsCalls; 61 62 /// ContainsDynamicAllocas - This is set to true if the cloned code contains 63 /// a 'dynamic' alloca. Dynamic allocas are allocas that are either not in 64 /// the entry block or they are in the entry block but are not a constant 65 /// size. 66 bool ContainsDynamicAllocas; 67 ClonedCodeInfoClonedCodeInfo68 ClonedCodeInfo() : ContainsCalls(false), ContainsDynamicAllocas(false) {} 69 }; 70 71 /// CloneBasicBlock - Return a copy of the specified basic block, but without 72 /// embedding the block into a particular function. The block returned is an 73 /// exact copy of the specified basic block, without any remapping having been 74 /// performed. Because of this, this is only suitable for applications where 75 /// the basic block will be inserted into the same function that it was cloned 76 /// from (loop unrolling would use this, for example). 77 /// 78 /// Also, note that this function makes a direct copy of the basic block, and 79 /// can thus produce illegal LLVM code. In particular, it will copy any PHI 80 /// nodes from the original block, even though there are no predecessors for the 81 /// newly cloned block (thus, phi nodes will have to be updated). Also, this 82 /// block will branch to the old successors of the original block: these 83 /// successors will have to have any PHI nodes updated to account for the new 84 /// incoming edges. 85 /// 86 /// The correlation between instructions in the source and result basic blocks 87 /// is recorded in the VMap map. 88 /// 89 /// If you have a particular suffix you'd like to use to add to any cloned 90 /// names, specify it as the optional third parameter. 91 /// 92 /// If you would like the basic block to be auto-inserted into the end of a 93 /// function, you can specify it as the optional fourth parameter. 94 /// 95 /// If you would like to collect additional information about the cloned 96 /// function, you can specify a ClonedCodeInfo object with the optional fifth 97 /// parameter. 98 /// 99 BasicBlock *CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap, 100 const Twine &NameSuffix = "", Function *F = nullptr, 101 ClonedCodeInfo *CodeInfo = nullptr); 102 103 /// CloneFunction - Return a copy of the specified function, but without 104 /// embedding the function into another module. Also, any references specified 105 /// in the VMap are changed to refer to their mapped value instead of the 106 /// original one. If any of the arguments to the function are in the VMap, 107 /// the arguments are deleted from the resultant function. The VMap is 108 /// updated to include mappings from all of the instructions and basicblocks in 109 /// the function from their old to new values. The final argument captures 110 /// information about the cloned code if non-null. 111 /// 112 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue 113 /// mappings, and debug info metadata will not be cloned. 114 /// 115 Function *CloneFunction(const Function *F, ValueToValueMapTy &VMap, 116 bool ModuleLevelChanges, 117 ClonedCodeInfo *CodeInfo = nullptr); 118 119 /// Clone OldFunc into NewFunc, transforming the old arguments into references 120 /// to VMap values. Note that if NewFunc already has basic blocks, the ones 121 /// cloned into it will be added to the end of the function. This function 122 /// fills in a list of return instructions, and can optionally remap types 123 /// and/or append the specified suffix to all values cloned. 124 /// 125 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue 126 /// mappings. 127 /// 128 void CloneFunctionInto(Function *NewFunc, const Function *OldFunc, 129 ValueToValueMapTy &VMap, bool ModuleLevelChanges, 130 SmallVectorImpl<ReturnInst*> &Returns, 131 const char *NameSuffix = "", 132 ClonedCodeInfo *CodeInfo = nullptr, 133 ValueMapTypeRemapper *TypeMapper = nullptr, 134 ValueMaterializer *Materializer = nullptr); 135 136 /// A helper class used with CloneAndPruneIntoFromInst to change the default 137 /// behavior while instructions are being cloned. 138 class CloningDirector { 139 public: 140 /// This enumeration describes the way CloneAndPruneIntoFromInst should 141 /// proceed after the CloningDirector has examined an instruction. 142 enum CloningAction { 143 ///< Continue cloning the instruction (default behavior). 144 CloneInstruction, 145 ///< Skip this instruction but continue cloning the current basic block. 146 SkipInstruction, 147 ///< Skip this instruction and stop cloning the current basic block. 148 StopCloningBB, 149 ///< Don't clone the terminator but clone the current block's successors. 150 CloneSuccessors 151 }; 152 ~CloningDirector()153 virtual ~CloningDirector() {} 154 155 /// Subclasses must override this function to customize cloning behavior. 156 virtual CloningAction handleInstruction(ValueToValueMapTy &VMap, 157 const Instruction *Inst, 158 BasicBlock *NewBB) = 0; 159 getTypeRemapper()160 virtual ValueMapTypeRemapper *getTypeRemapper() { return nullptr; } getValueMaterializer()161 virtual ValueMaterializer *getValueMaterializer() { return nullptr; } 162 }; 163 164 void CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc, 165 const Instruction *StartingInst, 166 ValueToValueMapTy &VMap, bool ModuleLevelChanges, 167 SmallVectorImpl<ReturnInst*> &Returns, 168 const char *NameSuffix = "", 169 ClonedCodeInfo *CodeInfo = nullptr, 170 CloningDirector *Director = nullptr); 171 172 173 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto, 174 /// except that it does some simple constant prop and DCE on the fly. The 175 /// effect of this is to copy significantly less code in cases where (for 176 /// example) a function call with constant arguments is inlined, and those 177 /// constant arguments cause a significant amount of code in the callee to be 178 /// dead. Since this doesn't produce an exactly copy of the input, it can't be 179 /// used for things like CloneFunction or CloneModule. 180 /// 181 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue 182 /// mappings. 183 /// 184 void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc, 185 ValueToValueMapTy &VMap, bool ModuleLevelChanges, 186 SmallVectorImpl<ReturnInst*> &Returns, 187 const char *NameSuffix = "", 188 ClonedCodeInfo *CodeInfo = nullptr, 189 Instruction *TheCall = nullptr); 190 191 /// InlineFunctionInfo - This class captures the data input to the 192 /// InlineFunction call, and records the auxiliary results produced by it. 193 class InlineFunctionInfo { 194 public: 195 explicit InlineFunctionInfo(CallGraph *cg = nullptr, 196 AliasAnalysis *AA = nullptr, 197 AssumptionCacheTracker *ACT = nullptr) CG(cg)198 : CG(cg), AA(AA), ACT(ACT) {} 199 200 /// CG - If non-null, InlineFunction will update the callgraph to reflect the 201 /// changes it makes. 202 CallGraph *CG; 203 AliasAnalysis *AA; 204 AssumptionCacheTracker *ACT; 205 206 /// StaticAllocas - InlineFunction fills this in with all static allocas that 207 /// get copied into the caller. 208 SmallVector<AllocaInst *, 4> StaticAllocas; 209 210 /// InlinedCalls - InlineFunction fills this in with callsites that were 211 /// inlined from the callee. This is only filled in if CG is non-null. 212 SmallVector<WeakVH, 8> InlinedCalls; 213 reset()214 void reset() { 215 StaticAllocas.clear(); 216 InlinedCalls.clear(); 217 } 218 }; 219 220 /// InlineFunction - This function inlines the called function into the basic 221 /// block of the caller. This returns false if it is not possible to inline 222 /// this call. The program is still in a well defined state if this occurs 223 /// though. 224 /// 225 /// Note that this only does one level of inlining. For example, if the 226 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now 227 /// exists in the instruction stream. Similarly this will inline a recursive 228 /// function by one level. 229 /// 230 bool InlineFunction(CallInst *C, InlineFunctionInfo &IFI, 231 bool InsertLifetime = true); 232 bool InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI, 233 bool InsertLifetime = true); 234 bool InlineFunction(CallSite CS, InlineFunctionInfo &IFI, 235 bool InsertLifetime = true); 236 237 /// \brief Clones a loop \p OrigLoop. Returns the loop and the blocks in \p 238 /// Blocks. 239 /// 240 /// Updates LoopInfo and DominatorTree assuming the loop is dominated by block 241 /// \p LoopDomBB. Insert the new blocks before block specified in \p Before. 242 Loop *cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB, 243 Loop *OrigLoop, ValueToValueMapTy &VMap, 244 const Twine &NameSuffix, LoopInfo *LI, 245 DominatorTree *DT, 246 SmallVectorImpl<BasicBlock *> &Blocks); 247 248 /// \brief Remaps instructions in \p Blocks using the mapping in \p VMap. 249 void remapInstructionsInBlocks(const SmallVectorImpl<BasicBlock *> &Blocks, 250 ValueToValueMapTy &VMap); 251 252 } // End llvm namespace 253 254 #endif 255