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/Analysis/AssumptionCache.h" 25 #include "llvm/IR/CallSite.h" 26 #include "llvm/IR/ValueHandle.h" 27 #include "llvm/Transforms/Utils/ValueMapper.h" 28 #include <functional> 29 #include <memory> 30 #include <vector> 31 32 namespace llvm { 33 34 class AllocaInst; 35 class BasicBlock; 36 class BlockFrequencyInfo; 37 class CallInst; 38 class CallGraph; 39 class DebugInfoFinder; 40 class DominatorTree; 41 class Function; 42 class Instruction; 43 class InvokeInst; 44 class Loop; 45 class LoopInfo; 46 class Module; 47 class ProfileSummaryInfo; 48 class ReturnInst; 49 50 /// Return an exact copy of the specified module 51 /// 52 std::unique_ptr<Module> CloneModule(const Module *M); 53 std::unique_ptr<Module> CloneModule(const Module *M, ValueToValueMapTy &VMap); 54 55 /// Return a copy of the specified module. The ShouldCloneDefinition function 56 /// controls whether a specific GlobalValue's definition is cloned. If the 57 /// function returns false, the module copy will contain an external reference 58 /// in place of the global definition. 59 std::unique_ptr<Module> 60 CloneModule(const Module *M, ValueToValueMapTy &VMap, 61 function_ref<bool(const GlobalValue *)> ShouldCloneDefinition); 62 63 /// ClonedCodeInfo - This struct can be used to capture information about code 64 /// being cloned, while it is being cloned. 65 struct ClonedCodeInfo { 66 /// ContainsCalls - This is set to true if the cloned code contains a normal 67 /// call instruction. 68 bool ContainsCalls = false; 69 70 /// ContainsDynamicAllocas - This is set to true if the cloned code contains 71 /// a 'dynamic' alloca. Dynamic allocas are allocas that are either not in 72 /// the entry block or they are in the entry block but are not a constant 73 /// size. 74 bool ContainsDynamicAllocas = false; 75 76 /// All cloned call sites that have operand bundles attached are appended to 77 /// this vector. This vector may contain nulls or undefs if some of the 78 /// originally inserted callsites were DCE'ed after they were cloned. 79 std::vector<WeakTrackingVH> OperandBundleCallSites; 80 81 ClonedCodeInfo() = default; 82 }; 83 84 /// CloneBasicBlock - Return a copy of the specified basic block, but without 85 /// embedding the block into a particular function. The block returned is an 86 /// exact copy of the specified basic block, without any remapping having been 87 /// performed. Because of this, this is only suitable for applications where 88 /// the basic block will be inserted into the same function that it was cloned 89 /// from (loop unrolling would use this, for example). 90 /// 91 /// Also, note that this function makes a direct copy of the basic block, and 92 /// can thus produce illegal LLVM code. In particular, it will copy any PHI 93 /// nodes from the original block, even though there are no predecessors for the 94 /// newly cloned block (thus, phi nodes will have to be updated). Also, this 95 /// block will branch to the old successors of the original block: these 96 /// successors will have to have any PHI nodes updated to account for the new 97 /// incoming edges. 98 /// 99 /// The correlation between instructions in the source and result basic blocks 100 /// is recorded in the VMap map. 101 /// 102 /// If you have a particular suffix you'd like to use to add to any cloned 103 /// names, specify it as the optional third parameter. 104 /// 105 /// If you would like the basic block to be auto-inserted into the end of a 106 /// function, you can specify it as the optional fourth parameter. 107 /// 108 /// If you would like to collect additional information about the cloned 109 /// function, you can specify a ClonedCodeInfo object with the optional fifth 110 /// parameter. 111 /// 112 BasicBlock *CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap, 113 const Twine &NameSuffix = "", Function *F = nullptr, 114 ClonedCodeInfo *CodeInfo = nullptr, 115 DebugInfoFinder *DIFinder = nullptr); 116 117 /// CloneFunction - Return a copy of the specified function and add it to that 118 /// function's module. Also, any references specified in the VMap are changed 119 /// to refer to their mapped value instead of the original one. If any of the 120 /// arguments to the function are in the VMap, the arguments are deleted from 121 /// the resultant function. The VMap is updated to include mappings from all of 122 /// the instructions and basicblocks in the function from their old to new 123 /// values. The final argument captures information about the cloned code if 124 /// non-null. 125 /// 126 /// VMap contains no non-identity GlobalValue mappings and debug info metadata 127 /// will not be cloned. 128 /// 129 Function *CloneFunction(Function *F, ValueToValueMapTy &VMap, 130 ClonedCodeInfo *CodeInfo = nullptr); 131 132 /// Clone OldFunc into NewFunc, transforming the old arguments into references 133 /// to VMap values. Note that if NewFunc already has basic blocks, the ones 134 /// cloned into it will be added to the end of the function. This function 135 /// fills in a list of return instructions, and can optionally remap types 136 /// and/or append the specified suffix to all values cloned. 137 /// 138 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue 139 /// mappings. 140 /// 141 void CloneFunctionInto(Function *NewFunc, const Function *OldFunc, 142 ValueToValueMapTy &VMap, bool ModuleLevelChanges, 143 SmallVectorImpl<ReturnInst*> &Returns, 144 const char *NameSuffix = "", 145 ClonedCodeInfo *CodeInfo = nullptr, 146 ValueMapTypeRemapper *TypeMapper = nullptr, 147 ValueMaterializer *Materializer = nullptr); 148 149 void CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc, 150 const Instruction *StartingInst, 151 ValueToValueMapTy &VMap, bool ModuleLevelChanges, 152 SmallVectorImpl<ReturnInst *> &Returns, 153 const char *NameSuffix = "", 154 ClonedCodeInfo *CodeInfo = nullptr); 155 156 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto, 157 /// except that it does some simple constant prop and DCE on the fly. The 158 /// effect of this is to copy significantly less code in cases where (for 159 /// example) a function call with constant arguments is inlined, and those 160 /// constant arguments cause a significant amount of code in the callee to be 161 /// dead. Since this doesn't produce an exactly copy of the input, it can't be 162 /// used for things like CloneFunction or CloneModule. 163 /// 164 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue 165 /// mappings. 166 /// 167 void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc, 168 ValueToValueMapTy &VMap, bool ModuleLevelChanges, 169 SmallVectorImpl<ReturnInst*> &Returns, 170 const char *NameSuffix = "", 171 ClonedCodeInfo *CodeInfo = nullptr, 172 Instruction *TheCall = nullptr); 173 174 /// InlineFunctionInfo - This class captures the data input to the 175 /// InlineFunction call, and records the auxiliary results produced by it. 176 class InlineFunctionInfo { 177 public: 178 explicit InlineFunctionInfo(CallGraph *cg = nullptr, 179 std::function<AssumptionCache &(Function &)> 180 *GetAssumptionCache = nullptr, 181 ProfileSummaryInfo *PSI = nullptr, 182 BlockFrequencyInfo *CallerBFI = nullptr, 183 BlockFrequencyInfo *CalleeBFI = nullptr) 184 : CG(cg), GetAssumptionCache(GetAssumptionCache), PSI(PSI), 185 CallerBFI(CallerBFI), CalleeBFI(CalleeBFI) {} 186 187 /// CG - If non-null, InlineFunction will update the callgraph to reflect the 188 /// changes it makes. 189 CallGraph *CG; 190 std::function<AssumptionCache &(Function &)> *GetAssumptionCache; 191 ProfileSummaryInfo *PSI; 192 BlockFrequencyInfo *CallerBFI, *CalleeBFI; 193 194 /// StaticAllocas - InlineFunction fills this in with all static allocas that 195 /// get copied into the caller. 196 SmallVector<AllocaInst *, 4> StaticAllocas; 197 198 /// InlinedCalls - InlineFunction fills this in with callsites that were 199 /// inlined from the callee. This is only filled in if CG is non-null. 200 SmallVector<WeakTrackingVH, 8> InlinedCalls; 201 202 /// All of the new call sites inlined into the caller. 203 /// 204 /// 'InlineFunction' fills this in by scanning the inlined instructions, and 205 /// only if CG is null. If CG is non-null, instead the value handle 206 /// `InlinedCalls` above is used. 207 SmallVector<CallSite, 8> InlinedCallSites; 208 209 void reset() { 210 StaticAllocas.clear(); 211 InlinedCalls.clear(); 212 InlinedCallSites.clear(); 213 } 214 }; 215 216 /// InlineFunction - This function inlines the called function into the basic 217 /// block of the caller. This returns false if it is not possible to inline 218 /// this call. The program is still in a well defined state if this occurs 219 /// though. 220 /// 221 /// Note that this only does one level of inlining. For example, if the 222 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now 223 /// exists in the instruction stream. Similarly this will inline a recursive 224 /// function by one level. 225 /// 226 /// Note that while this routine is allowed to cleanup and optimize the 227 /// *inlined* code to minimize the actual inserted code, it must not delete 228 /// code in the caller as users of this routine may have pointers to 229 /// instructions in the caller that need to remain stable. 230 bool InlineFunction(CallInst *C, InlineFunctionInfo &IFI, 231 AAResults *CalleeAAR = nullptr, bool InsertLifetime = true); 232 bool InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI, 233 AAResults *CalleeAAR = nullptr, bool InsertLifetime = true); 234 bool InlineFunction(CallSite CS, InlineFunctionInfo &IFI, 235 AAResults *CalleeAAR = nullptr, 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 /// Note: Only innermost loops are supported. 243 Loop *cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB, 244 Loop *OrigLoop, ValueToValueMapTy &VMap, 245 const Twine &NameSuffix, LoopInfo *LI, 246 DominatorTree *DT, 247 SmallVectorImpl<BasicBlock *> &Blocks); 248 249 /// \brief Remaps instructions in \p Blocks using the mapping in \p VMap. 250 void remapInstructionsInBlocks(const SmallVectorImpl<BasicBlock *> &Blocks, 251 ValueToValueMapTy &VMap); 252 253 /// Split edge between BB and PredBB and duplicate all non-Phi instructions 254 /// from BB between its beginning and the StopAt instruction into the split 255 /// block. Phi nodes are not duplicated, but their uses are handled correctly: 256 /// we replace them with the uses of corresponding Phi inputs. ValueMapping 257 /// is used to map the original instructions from BB to their newly-created 258 /// copies. Returns the split block. 259 BasicBlock * 260 DuplicateInstructionsInSplitBetween(BasicBlock *BB, BasicBlock *PredBB, 261 Instruction *StopAt, 262 ValueToValueMapTy &ValueMapping); 263 } // end namespace llvm 264 265 #endif // LLVM_TRANSFORMS_UTILS_CLONING_H 266
