TargetRegisterInfo.cpp

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//===- TargetRegisterInfo.cpp - Target Register Information Implementation ===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the TargetRegisterInfo interface.
//
//===----------------------------------------------------------------------===//

#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/ADT/BitVector.h"

using namespace llvm;

TargetRegisterInfo::TargetRegisterInfo(const TargetRegisterDesc *D, unsigned NR,
                             regclass_iterator RCB, regclass_iterator RCE,
                             int CFSO, int CFDO,
                             const unsigned* subregs, const unsigned subregsize)
  : SubregHash(subregs), SubregHashSize(subregsize), Desc(D), NumRegs(NR),
    RegClassBegin(RCB), RegClassEnd(RCE) {
  assert(NumRegs < FirstVirtualRegister &&
         "Target has too many physical registers!");

  CallFrameSetupOpcode   = CFSO;
  CallFrameDestroyOpcode = CFDO;
}

TargetRegisterInfo::~TargetRegisterInfo() {}

/// getPhysicalRegisterRegClass - Returns the Register Class of a physical
/// register of the given type. If type is MVT::Other, then just return any
/// register class the register belongs to.
const TargetRegisterClass *
TargetRegisterInfo::getPhysicalRegisterRegClass(unsigned reg, MVT VT) const {
  assert(isPhysicalRegister(reg) && "reg must be a physical register");

  // Pick the most super register class of the right type that contains
  // this physreg.
  const TargetRegisterClass* BestRC = 0;
  for (regclass_iterator I = regclass_begin(), E = regclass_end(); I != E; ++I){
    const TargetRegisterClass* RC = *I;
    if ((VT == MVT::Other || RC->hasType(VT)) && RC->contains(reg) &&
        (!BestRC || BestRC->hasSuperClass(RC)))
      BestRC = RC;
  }

  assert(BestRC && "Couldn't find the register class");
  return BestRC;
}

/// getAllocatableSetForRC - Toggle the bits that represent allocatable
/// registers for the specific register class.
static void getAllocatableSetForRC(MachineFunction &MF,
                                   const TargetRegisterClass *RC, BitVector &R){  
  for (TargetRegisterClass::iterator I = RC->allocation_order_begin(MF),
         E = RC->allocation_order_end(MF); I != E; ++I)
    R.set(*I);
}

BitVector TargetRegisterInfo::getAllocatableSet(MachineFunction &MF,
                                          const TargetRegisterClass *RC) const {
  BitVector Allocatable(NumRegs);
  if (RC) {
    getAllocatableSetForRC(MF, RC, Allocatable);
    return Allocatable;
  }

  for (TargetRegisterInfo::regclass_iterator I = regclass_begin(),
         E = regclass_end(); I != E; ++I)
    getAllocatableSetForRC(MF, *I, Allocatable);
  return Allocatable;
}

/// getFrameIndexOffset - Returns the displacement from the frame register to
/// the stack frame of the specified index. This is the default implementation
/// which is likely incorrect for the target.
int TargetRegisterInfo::getFrameIndexOffset(MachineFunction &MF, int FI) const {
  const TargetFrameInfo &TFI = *MF.getTarget().getFrameInfo();
  MachineFrameInfo *MFI = MF.getFrameInfo();
  return MFI->getObjectOffset(FI) + MFI->getStackSize() -
    TFI.getOffsetOfLocalArea() + MFI->getOffsetAdjustment();
}

/// getInitialFrameState - Returns a list of machine moves that are assumed
/// on entry to a function.
void
TargetRegisterInfo::getInitialFrameState(std::vector<MachineMove> &Moves) const {
  // Default is to do nothing.
}