lib/CodeGen/CriticalAntiDepBreaker.h

   1 //=- llvm/CodeGen/CriticalAntiDepBreaker.h - Anti-Dep Support -*- 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 CriticalAntiDepBreaker class, which
  11 // implements register anti-dependence breaking along a blocks
  12 // critical path during post-RA scheduler.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #ifndef LLVM_CODEGEN_CRITICALANTIDEPBREAKER_H
  17 #define LLVM_CODEGEN_CRITICALANTIDEPBREAKER_H
  18
  19 #include "AntiDepBreaker.h"
  20 #include "RegisterClassInfo.h"
  21 #include "llvm/CodeGen/MachineBasicBlock.h"
  22 #include "llvm/CodeGen/MachineFrameInfo.h"
  23 #include "llvm/CodeGen/MachineFunction.h"
  24 #include "llvm/CodeGen/MachineRegisterInfo.h"
  25 #include "llvm/CodeGen/ScheduleDAG.h"
  26 #include "llvm/ADT/BitVector.h"
  27 #include "llvm/ADT/SmallSet.h"
  28 #include <map>
  29
  30 namespace llvm {
  31 class RegisterClassInfo;
  32 class TargetInstrInfo;
  33 class TargetRegisterInfo;
  34
  35   class CriticalAntiDepBreaker : public AntiDepBreaker {
  36     MachineFunction& MF;
  37     MachineRegisterInfo &MRI;
  38     const TargetInstrInfo *TII;
  39     const TargetRegisterInfo *TRI;
  40     const RegisterClassInfo &RegClassInfo;
  41
  42     /// AllocatableSet - The set of allocatable registers.
  43     /// We'll be ignoring anti-dependencies on non-allocatable registers,
  44     /// because they may not be safe to break.
  45     const BitVector AllocatableSet;
  46
  47     /// Classes - For live regs that are only used in one register class in a
  48     /// live range, the register class. If the register is not live, the
  49     /// corresponding value is null. If the register is live but used in
  50     /// multiple register classes, the corresponding value is -1 casted to a
  51     /// pointer.
  52     std::vector<const TargetRegisterClass*> Classes;
  53
  54     /// RegRefs - Map registers to all their references within a live range.
  55     std::multimap<unsigned, MachineOperand *> RegRefs;
  56     typedef std::multimap<unsigned, MachineOperand *>::const_iterator
  57       RegRefIter;
  58
  59     /// KillIndices - The index of the most recent kill (proceding bottom-up),
  60     /// or ~0u if the register is not live.
  61     std::vector<unsigned> KillIndices;
  62
  63     /// DefIndices - The index of the most recent complete def (proceding bottom
  64     /// up), or ~0u if the register is live.
  65     std::vector<unsigned> DefIndices;
  66
  67     /// KeepRegs - A set of registers which are live and cannot be changed to
  68     /// break anti-dependencies.
  69     SmallSet<unsigned, 4> KeepRegs;
  70
  71   public:
  72     CriticalAntiDepBreaker(MachineFunction& MFi, const RegisterClassInfo&);
  73     ~CriticalAntiDepBreaker();
  74
  75     /// Start - Initialize anti-dep breaking for a new basic block.
  76     void StartBlock(MachineBasicBlock *BB);
  77
  78     /// BreakAntiDependencies - Identifiy anti-dependencies along the critical
  79     /// path
  80     /// of the ScheduleDAG and break them by renaming registers.
  81     ///
  82     unsigned BreakAntiDependencies(const std::vector<SUnit>& SUnits,
  83                                    MachineBasicBlock::iterator Begin,
  84                                    MachineBasicBlock::iterator End,
  85                                    unsigned InsertPosIndex,
  86                                    DbgValueVector &DbgValues);
  87
  88     /// Observe - Update liveness information to account for the current
  89     /// instruction, which will not be scheduled.
  90     ///
  91     void Observe(MachineInstr *MI, unsigned Count, unsigned InsertPosIndex);
  92
  93     /// Finish - Finish anti-dep breaking for a basic block.
  94     void FinishBlock();
  95
  96   private:
  97     void PrescanInstruction(MachineInstr *MI);
  98     void ScanInstruction(MachineInstr *MI, unsigned Count);
  99     bool isNewRegClobberedByRefs(RegRefIter RegRefBegin,
 100                                  RegRefIter RegRefEnd,
 101                                  unsigned NewReg);
 102     unsigned findSuitableFreeRegister(RegRefIter RegRefBegin,
 103                                       RegRefIter RegRefEnd,
 104                                       unsigned AntiDepReg,
 105                                       unsigned LastNewReg,
 106                                       const TargetRegisterClass *RC);
 107   };
 108 }
 109
 110 #endif