llvm/MC/MCRegisterInfo.h

//=== MC/MCRegisterInfo.h - Target Register Description ---------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file describes an abstract interface used to get information about a
// target machines register file.  This information is used for a variety of
// purposed, especially register allocation.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_MC_MCREGISTERINFO_H
#define LLVM_MC_MCREGISTERINFO_H

#include "llvm/ADT/DenseMap.h"
#include <cassert>

namespace llvm {

/// MCRegisterDesc - This record contains all of the information known about
/// a particular register.  The Overlaps field contains a pointer to a zero
/// terminated array of registers that this register aliases, starting with
/// itself. This is needed for architectures like X86 which have AL alias AX
/// alias EAX. The SubRegs field is a zero terminated array of registers that
/// are sub-registers of the specific register, e.g. AL, AH are sub-registers of
/// AX. The SuperRegs field is a zero terminated array of registers that are
/// super-registers of the specific register, e.g. RAX, EAX, are super-registers
/// of AX.
///
struct MCRegisterDesc {
  const char     *Name;         // Printable name for the reg (for debugging)
  const unsigned *Overlaps;     // Overlapping registers, described above
  const unsigned *SubRegs;      // Sub-register set, described above
  const unsigned *SuperRegs;    // Super-register set, described above
};

/// MCRegisterInfo base class - We assume that the target defines a static
/// array of MCRegisterDesc objects that represent all of the machine
/// registers that the target has.  As such, we simply have to track a pointer
/// to this array so that we can turn register number into a register
/// descriptor.
///
/// Note this class is designed to be a base class of TargetRegisterInfo, which
/// is the interface used by codegen. However, specific targets *should never*
/// specialize this class. MCRegisterInfo should only contain getters to access
/// TableGen generated physical register data. It must not be extended with
/// virtual methods.
///
class MCRegisterInfo {
private:
  const MCRegisterDesc *Desc;                 // Pointer to the descriptor array
  unsigned NumRegs;                           // Number of entries in the array
  unsigned RAReg;                             // Return address register
  DenseMap<unsigned, int> L2DwarfRegs;        // LLVM to Dwarf regs mapping
  DenseMap<unsigned, int> EHL2DwarfRegs;      // LLVM to Dwarf regs mapping EH
  DenseMap<unsigned, unsigned> Dwarf2LRegs;   // Dwarf to LLVM regs mapping
  DenseMap<unsigned, unsigned> EHDwarf2LRegs; // Dwarf to LLVM regs mapping EH
  DenseMap<unsigned, int> L2SEHRegs;          // LLVM to SEH regs mapping

public:
  /// InitMCRegisterInfo - Initialize MCRegisterInfo, called by TableGen
  /// auto-generated routines. *DO NOT USE*.
  void InitMCRegisterInfo(const MCRegisterDesc *D, unsigned NR, unsigned RA) {
    Desc = D;
    NumRegs = NR;
    RAReg = RA;
  }

  /// mapLLVMRegToDwarfReg - Used to initialize LLVM register to Dwarf
  /// register number mapping. Called by TableGen auto-generated routines.
  /// *DO NOT USE*.
  void mapLLVMRegToDwarfReg(unsigned LLVMReg, int DwarfReg, bool isEH) {
    if (isEH)
      EHL2DwarfRegs[LLVMReg] = DwarfReg;
    else
      L2DwarfRegs[LLVMReg] = DwarfReg;
  }

  /// mapDwarfRegToLLVMReg - Used to initialize Dwarf register to LLVM
  /// register number mapping. Called by TableGen auto-generated routines.
  /// *DO NOT USE*.
  void mapDwarfRegToLLVMReg(unsigned DwarfReg, unsigned LLVMReg, bool isEH) {
    if (isEH)
      EHDwarf2LRegs[DwarfReg] = LLVMReg;
    else
      Dwarf2LRegs[DwarfReg] = LLVMReg;
  }

  /// mapLLVMRegToSEHReg - Used to initialize LLVM register to SEH register
  /// number mapping. By default the SEH register number is just the same
  /// as the LLVM register number.
  /// FIXME: TableGen these numbers. Currently this requires target specific
  /// initialization code.
  void mapLLVMRegToSEHReg(unsigned LLVMReg, int SEHReg) {
    L2SEHRegs[LLVMReg] = SEHReg;
  }

  /// getRARegister - This method should return the register where the return
  /// address can be found.
  unsigned getRARegister() const {
    return RAReg;
  }

  const MCRegisterDesc &operator[](unsigned RegNo) const {
    assert(RegNo < NumRegs &&
           "Attempting to access record for invalid register number!");
    return Desc[RegNo];
  }

  /// Provide a get method, equivalent to [], but more useful if we have a
  /// pointer to this object.
  ///
  const MCRegisterDesc &get(unsigned RegNo) const {
    return operator[](RegNo);
  }

  /// getAliasSet - Return the set of registers aliased by the specified
  /// register, or a null list of there are none.  The list returned is zero
  /// terminated.
  ///
  const unsigned *getAliasSet(unsigned RegNo) const {
    // The Overlaps set always begins with Reg itself.
    return get(RegNo).Overlaps + 1;
  }

  /// getOverlaps - Return a list of registers that overlap Reg, including
  /// itself. This is the same as the alias set except Reg is included in the
  /// list.
  /// These are exactly the registers in { x | regsOverlap(x, Reg) }.
  ///
  const unsigned *getOverlaps(unsigned RegNo) const {
    return get(RegNo).Overlaps;
  }

  /// getSubRegisters - Return the list of registers that are sub-registers of
  /// the specified register, or a null list of there are none. The list
  /// returned is zero terminated and sorted according to super-sub register
  /// relations. e.g. X86::RAX's sub-register list is EAX, AX, AL, AH.
  ///
  const unsigned *getSubRegisters(unsigned RegNo) const {
    return get(RegNo).SubRegs;
  }

  /// getSuperRegisters - Return the list of registers that are super-registers
  /// of the specified register, or a null list of there are none. The list
  /// returned is zero terminated and sorted according to super-sub register
  /// relations. e.g. X86::AL's super-register list is AX, EAX, RAX.
  ///
  const unsigned *getSuperRegisters(unsigned RegNo) const {
    return get(RegNo).SuperRegs;
  }

  /// getName - Return the human-readable symbolic target-specific name for the
  /// specified physical register.
  const char *getName(unsigned RegNo) const {
    return get(RegNo).Name;
  }

  /// getNumRegs - Return the number of registers this target has (useful for
  /// sizing arrays holding per register information)
  unsigned getNumRegs() const {
    return NumRegs;
  }

  /// getDwarfRegNum - Map a target register to an equivalent dwarf register
  /// number.  Returns -1 if there is no equivalent value.  The second
  /// parameter allows targets to use different numberings for EH info and
  /// debugging info.
  int getDwarfRegNum(unsigned RegNum, bool isEH) const {
    const DenseMap<unsigned, int> &M = isEH ? EHL2DwarfRegs : L2DwarfRegs;
    const DenseMap<unsigned, int>::const_iterator I = M.find(RegNum);
    if (I == M.end()) return -1;
    return I->second;
  }

  /// getLLVMRegNum - Map a dwarf register back to a target register.
  ///
  int getLLVMRegNum(unsigned RegNum, bool isEH) const {
    const DenseMap<unsigned, unsigned> &M = isEH ? EHDwarf2LRegs : Dwarf2LRegs;
    const DenseMap<unsigned, unsigned>::const_iterator I = M.find(RegNum);
    if (I == M.end()) {
      assert(0 && "Invalid RegNum");
      return -1;
    }
    return I->second;
  }

  /// getSEHRegNum - Map a target register to an equivalent SEH register
  /// number.  Returns LLVM register number if there is no equivalent value.
  int getSEHRegNum(unsigned RegNum) const {
    const DenseMap<unsigned, int>::const_iterator I = L2SEHRegs.find(RegNum);
    if (I == L2SEHRegs.end()) return (int)RegNum;
    return I->second;
  }
};

} // End llvm namespace

#endif