lib/CodeGen/AntiDepBreaker.h

   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_CODEGEN_ANTIDEPBREAKER_H
  16 #define LLVM_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 /// AntiDepBreaker - This class works into conjunction with the
  29 /// post-RA scheduler to rename registers to break register
  30 /// anti-dependencies.
  31 class AntiDepBreaker {
  32 public:
  33   typedef std::vector<std::pair<MachineInstr *, MachineInstr *> >
  34     DbgValueVector;
  35
  36   virtual ~AntiDepBreaker();
  37
  38   /// Start - Initialize anti-dep breaking for a new basic block.
  39   virtual void StartBlock(MachineBasicBlock *BB) =0;
  40
  41   /// BreakAntiDependencies - Identifiy anti-dependencies within a
  42   /// basic-block region and break them by renaming registers. Return
  43   /// the number of anti-dependencies broken.
  44   ///
  45   virtual unsigned BreakAntiDependencies(const std::vector<SUnit>& SUnits,
  46                                          MachineBasicBlock::iterator Begin,
  47                                          MachineBasicBlock::iterator End,
  48                                          unsigned InsertPosIndex,
  49                                          DbgValueVector &DbgValues) = 0;
  50
  51   /// Observe - Update liveness information to account for the current
  52   /// instruction, which will not be scheduled.
  53   ///
  54   virtual void Observe(MachineInstr *MI, unsigned Count,
  55                        unsigned InsertPosIndex) =0;
  56
  57   /// Finish - Finish anti-dep breaking for a basic block.
  58   virtual void FinishBlock() =0;
  59
  60   /// UpdateDbgValue - Update DBG_VALUE if dependency breaker is updating
  61   /// other machine instruction to use NewReg.
  62   void UpdateDbgValue(MachineInstr *MI, unsigned OldReg, unsigned NewReg) {
  63     assert (MI->isDebugValue() && "MI is not DBG_VALUE!");
  64     if (MI && MI->getOperand(0).isReg() && MI->getOperand(0).getReg() == OldReg)
  65       MI->getOperand(0).setReg(NewReg);
  66   }
  67 };
  68
  69 }
  70
  71 #endif