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