1 //===- PHITransAddr.h - PHI Translation for Addresses -----------*- 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 declares the PHITransAddr class. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_ANALYSIS_PHITRANSADDR_H 15 #define LLVM_ANALYSIS_PHITRANSADDR_H 16 17 #include "llvm/ADT/SmallVector.h" 18 #include "llvm/IR/Instruction.h" 19 20 namespace llvm { 21 class AssumptionCache; 22 class DominatorTree; 23 class DataLayout; 24 class TargetLibraryInfo; 25 26 /// PHITransAddr - An address value which tracks and handles phi translation. 27 /// As we walk "up" the CFG through predecessors, we need to ensure that the 28 /// address we're tracking is kept up to date. For example, if we're analyzing 29 /// an address of "&A[i]" and walk through the definition of 'i' which is a PHI 30 /// node, we *must* phi translate i to get "&A[j]" or else we will analyze an 31 /// incorrect pointer in the predecessor block. 32 /// 33 /// This is designed to be a relatively small object that lives on the stack and 34 /// is copyable. 35 /// 36 class PHITransAddr { 37 /// Addr - The actual address we're analyzing. 38 Value *Addr; 39 40 /// The DataLayout we are playing with. 41 const DataLayout &DL; 42 43 /// TLI - The target library info if known, otherwise null. 44 const TargetLibraryInfo *TLI; 45 46 /// A cache of @llvm.assume calls used by SimplifyInstruction. 47 AssumptionCache *AC; 48 49 /// InstInputs - The inputs for our symbolic address. 50 SmallVector<Instruction*, 4> InstInputs; 51 52 public: PHITransAddr(Value * addr,const DataLayout & DL,AssumptionCache * AC)53 PHITransAddr(Value *addr, const DataLayout &DL, AssumptionCache *AC) 54 : Addr(addr), DL(DL), TLI(nullptr), AC(AC) { 55 // If the address is an instruction, the whole thing is considered an input. 56 if (Instruction *I = dyn_cast<Instruction>(Addr)) 57 InstInputs.push_back(I); 58 } 59 getAddr()60 Value *getAddr() const { return Addr; } 61 62 /// NeedsPHITranslationFromBlock - Return true if moving from the specified 63 /// BasicBlock to its predecessors requires PHI translation. NeedsPHITranslationFromBlock(BasicBlock * BB)64 bool NeedsPHITranslationFromBlock(BasicBlock *BB) const { 65 // We do need translation if one of our input instructions is defined in 66 // this block. 67 for (unsigned i = 0, e = InstInputs.size(); i != e; ++i) 68 if (InstInputs[i]->getParent() == BB) 69 return true; 70 return false; 71 } 72 73 /// IsPotentiallyPHITranslatable - If this needs PHI translation, return true 74 /// if we have some hope of doing it. This should be used as a filter to 75 /// avoid calling PHITranslateValue in hopeless situations. 76 bool IsPotentiallyPHITranslatable() const; 77 78 /// PHITranslateValue - PHI translate the current address up the CFG from 79 /// CurBB to Pred, updating our state to reflect any needed changes. If 80 /// 'MustDominate' is true, the translated value must dominate 81 /// PredBB. This returns true on failure and sets Addr to null. 82 bool PHITranslateValue(BasicBlock *CurBB, BasicBlock *PredBB, 83 const DominatorTree *DT, bool MustDominate); 84 85 /// PHITranslateWithInsertion - PHI translate this value into the specified 86 /// predecessor block, inserting a computation of the value if it is 87 /// unavailable. 88 /// 89 /// All newly created instructions are added to the NewInsts list. This 90 /// returns null on failure. 91 /// 92 Value *PHITranslateWithInsertion(BasicBlock *CurBB, BasicBlock *PredBB, 93 const DominatorTree &DT, 94 SmallVectorImpl<Instruction *> &NewInsts); 95 96 void dump() const; 97 98 /// Verify - Check internal consistency of this data structure. If the 99 /// structure is valid, it returns true. If invalid, it prints errors and 100 /// returns false. 101 bool Verify() const; 102 103 private: 104 Value *PHITranslateSubExpr(Value *V, BasicBlock *CurBB, BasicBlock *PredBB, 105 const DominatorTree *DT); 106 107 /// InsertPHITranslatedSubExpr - Insert a computation of the PHI translated 108 /// version of 'V' for the edge PredBB->CurBB into the end of the PredBB 109 /// block. All newly created instructions are added to the NewInsts list. 110 /// This returns null on failure. 111 /// 112 Value *InsertPHITranslatedSubExpr(Value *InVal, BasicBlock *CurBB, 113 BasicBlock *PredBB, const DominatorTree &DT, 114 SmallVectorImpl<Instruction *> &NewInsts); 115 116 /// AddAsInput - If the specified value is an instruction, add it as an input. AddAsInput(Value * V)117 Value *AddAsInput(Value *V) { 118 // If V is an instruction, it is now an input. 119 if (Instruction *VI = dyn_cast<Instruction>(V)) 120 InstInputs.push_back(VI); 121 return V; 122 } 123 }; 124 125 } // end namespace llvm 126 127 #endif 128