PHITransAddr.h revision 200581
1200581Srdivacky//===- PHITransAddr.h - PHI Translation for Addresses -----------*- C++ -*-===// 2200581Srdivacky// 3200581Srdivacky// The LLVM Compiler Infrastructure 4200581Srdivacky// 5200581Srdivacky// This file is distributed under the University of Illinois Open Source 6200581Srdivacky// License. See LICENSE.TXT for details. 7200581Srdivacky// 8200581Srdivacky//===----------------------------------------------------------------------===// 9200581Srdivacky// 10200581Srdivacky// This file declares the PHITransAddr class. 11200581Srdivacky// 12200581Srdivacky//===----------------------------------------------------------------------===// 13200581Srdivacky 14200581Srdivacky#ifndef LLVM_ANALYSIS_PHITRANSADDR_H 15200581Srdivacky#define LLVM_ANALYSIS_PHITRANSADDR_H 16200581Srdivacky 17200581Srdivacky#include "llvm/Instruction.h" 18200581Srdivacky#include "llvm/ADT/SmallVector.h" 19200581Srdivacky 20200581Srdivackynamespace llvm { 21200581Srdivacky class DominatorTree; 22200581Srdivacky class TargetData; 23200581Srdivacky 24200581Srdivacky/// PHITransAddr - An address value which tracks and handles phi translation. 25200581Srdivacky/// As we walk "up" the CFG through predecessors, we need to ensure that the 26200581Srdivacky/// address we're tracking is kept up to date. For example, if we're analyzing 27200581Srdivacky/// an address of "&A[i]" and walk through the definition of 'i' which is a PHI 28200581Srdivacky/// node, we *must* phi translate i to get "&A[j]" or else we will analyze an 29200581Srdivacky/// incorrect pointer in the predecessor block. 30200581Srdivacky/// 31200581Srdivacky/// This is designed to be a relatively small object that lives on the stack and 32200581Srdivacky/// is copyable. 33200581Srdivacky/// 34200581Srdivackyclass PHITransAddr { 35200581Srdivacky /// Addr - The actual address we're analyzing. 36200581Srdivacky Value *Addr; 37200581Srdivacky 38200581Srdivacky /// TD - The target data we are playing with if known, otherwise null. 39200581Srdivacky const TargetData *TD; 40200581Srdivacky 41200581Srdivacky /// InstInputs - The inputs for our symbolic address. 42200581Srdivacky SmallVector<Instruction*, 4> InstInputs; 43200581Srdivackypublic: 44200581Srdivacky PHITransAddr(Value *addr, const TargetData *td) : Addr(addr), TD(td) { 45200581Srdivacky // If the address is an instruction, the whole thing is considered an input. 46200581Srdivacky if (Instruction *I = dyn_cast<Instruction>(Addr)) 47200581Srdivacky InstInputs.push_back(I); 48200581Srdivacky } 49200581Srdivacky 50200581Srdivacky Value *getAddr() const { return Addr; } 51200581Srdivacky 52200581Srdivacky /// NeedsPHITranslationFromBlock - Return true if moving from the specified 53200581Srdivacky /// BasicBlock to its predecessors requires PHI translation. 54200581Srdivacky bool NeedsPHITranslationFromBlock(BasicBlock *BB) const { 55200581Srdivacky // We do need translation if one of our input instructions is defined in 56200581Srdivacky // this block. 57200581Srdivacky for (unsigned i = 0, e = InstInputs.size(); i != e; ++i) 58200581Srdivacky if (InstInputs[i]->getParent() == BB) 59200581Srdivacky return true; 60200581Srdivacky return false; 61200581Srdivacky } 62200581Srdivacky 63200581Srdivacky /// IsPotentiallyPHITranslatable - If this needs PHI translation, return true 64200581Srdivacky /// if we have some hope of doing it. This should be used as a filter to 65200581Srdivacky /// avoid calling PHITranslateValue in hopeless situations. 66200581Srdivacky bool IsPotentiallyPHITranslatable() const; 67200581Srdivacky 68200581Srdivacky /// PHITranslateValue - PHI translate the current address up the CFG from 69200581Srdivacky /// CurBB to Pred, updating our state the reflect any needed changes. This 70200581Srdivacky /// returns true on failure and sets Addr to null. 71200581Srdivacky bool PHITranslateValue(BasicBlock *CurBB, BasicBlock *PredBB); 72200581Srdivacky 73200581Srdivacky /// PHITranslateWithInsertion - PHI translate this value into the specified 74200581Srdivacky /// predecessor block, inserting a computation of the value if it is 75200581Srdivacky /// unavailable. 76200581Srdivacky /// 77200581Srdivacky /// All newly created instructions are added to the NewInsts list. This 78200581Srdivacky /// returns null on failure. 79200581Srdivacky /// 80200581Srdivacky Value *PHITranslateWithInsertion(BasicBlock *CurBB, BasicBlock *PredBB, 81200581Srdivacky const DominatorTree &DT, 82200581Srdivacky SmallVectorImpl<Instruction*> &NewInsts); 83200581Srdivacky 84200581Srdivacky void dump() const; 85200581Srdivacky 86200581Srdivacky /// Verify - Check internal consistency of this data structure. If the 87200581Srdivacky /// structure is valid, it returns true. If invalid, it prints errors and 88200581Srdivacky /// returns false. 89200581Srdivacky bool Verify() const; 90200581Srdivackyprivate: 91200581Srdivacky Value *PHITranslateSubExpr(Value *V, BasicBlock *CurBB, BasicBlock *PredBB); 92200581Srdivacky 93200581Srdivacky 94200581Srdivacky /// GetAvailablePHITranslatedSubExpr - Return the value computed by 95200581Srdivacky /// PHITranslateSubExpr if it dominates PredBB, otherwise return null. 96200581Srdivacky Value *GetAvailablePHITranslatedSubExpr(Value *V, 97200581Srdivacky BasicBlock *CurBB, BasicBlock *PredBB, 98200581Srdivacky const DominatorTree &DT) const; 99200581Srdivacky 100200581Srdivacky /// InsertPHITranslatedSubExpr - Insert a computation of the PHI translated 101200581Srdivacky /// version of 'V' for the edge PredBB->CurBB into the end of the PredBB 102200581Srdivacky /// block. All newly created instructions are added to the NewInsts list. 103200581Srdivacky /// This returns null on failure. 104200581Srdivacky /// 105200581Srdivacky Value *InsertPHITranslatedSubExpr(Value *InVal, BasicBlock *CurBB, 106200581Srdivacky BasicBlock *PredBB, const DominatorTree &DT, 107200581Srdivacky SmallVectorImpl<Instruction*> &NewInsts); 108200581Srdivacky 109200581Srdivacky /// AddAsInput - If the specified value is an instruction, add it as an input. 110200581Srdivacky Value *AddAsInput(Value *V) { 111200581Srdivacky // If V is an instruction, it is now an input. 112200581Srdivacky if (Instruction *VI = dyn_cast<Instruction>(V)) 113200581Srdivacky InstInputs.push_back(VI); 114200581Srdivacky return V; 115200581Srdivacky } 116200581Srdivacky 117200581Srdivacky}; 118200581Srdivacky 119200581Srdivacky} // end namespace llvm 120200581Srdivacky 121200581Srdivacky#endif 122