1 //=- llvm/CodeGen/AntiDepBreaker.h - Anti-Dependence Breaking -*- 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 implements the AntiDepBreaker class, which implements 11 // anti-dependence breaking heuristics for post-register-allocation scheduling. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_LIB_CODEGEN_ANTIDEPBREAKER_H 16 #define LLVM_LIB_CODEGEN_ANTIDEPBREAKER_H 17 18 #include "llvm/CodeGen/MachineBasicBlock.h" 19 #include "llvm/CodeGen/MachineFrameInfo.h" 20 #include "llvm/CodeGen/MachineFunction.h" 21 #include "llvm/CodeGen/MachineRegisterInfo.h" 22 #include "llvm/CodeGen/ScheduleDAG.h" 23 #include "llvm/Target/TargetRegisterInfo.h" 24 #include <vector> 25 26 namespace llvm { 27 28 /// This class works in conjunction with the post-RA scheduler to rename 29 /// registers to break register anti-dependencies (WAR hazards). 30 class LLVM_LIBRARY_VISIBILITY AntiDepBreaker { 31 public: 32 typedef std::vector<std::pair<MachineInstr *, MachineInstr *> > 33 DbgValueVector; 34 35 virtual ~AntiDepBreaker(); 36 37 /// Initialize anti-dep breaking for a new basic block. 38 virtual void StartBlock(MachineBasicBlock *BB) =0; 39 40 /// Identifiy anti-dependencies within a basic-block region and break them by 41 /// renaming registers. Return the number of anti-dependencies broken. 42 virtual unsigned BreakAntiDependencies(const std::vector<SUnit>& SUnits, 43 MachineBasicBlock::iterator Begin, 44 MachineBasicBlock::iterator End, 45 unsigned InsertPosIndex, 46 DbgValueVector &DbgValues) = 0; 47 48 /// Update liveness information to account for the current 49 /// instruction, which will not be scheduled. 50 virtual void Observe(MachineInstr &MI, unsigned Count, 51 unsigned InsertPosIndex) = 0; 52 53 /// Finish anti-dep breaking for a basic block. 54 virtual void FinishBlock() =0; 55 56 /// Update DBG_VALUE if dependency breaker is updating 57 /// other machine instruction to use NewReg. 58 void UpdateDbgValue(MachineInstr &MI, unsigned OldReg, unsigned NewReg) { 59 assert(MI.isDebugValue() && "MI is not DBG_VALUE!"); 60 if (MI.getOperand(0).isReg() && MI.getOperand(0).getReg() == OldReg) 61 MI.getOperand(0).setReg(NewReg); 62 } 63 }; 64 65 } 66 67 #endif 68
