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