source: liacs/coco/assignment4/RegisterManager.h@ 20

#ifndef REGISTERMANAGER_H
#define REGISTERMANAGER_H

#include "Symbol.h"
#include "globals.h"
#include "StackFrameManager.h"
#include "AssemblerCode.h"

/* Keeps track of what registers are associated with symbols.
   Loads the appropriate registers and generates spill code if needed.
*/
class RegisterManager {
public:
  // constructor
  RegisterManager(StackFrameManager& sfm, AssemblerCode& ac);

  // Get the register associated with symbol.
  // Register is of same type as the return type of the symbol.
  // Generates loading code if needed.
  MRegisterType GetRegister(Symbol *symbol);

  // Gets an integer register associated with symbol.
  // Generates loading code if needed.
  MRegisterType GetIntRegister(Symbol *symbol);

  // Gets a float register associated with symbol.
  // Generates loading code if needed.
  MRegisterType GetFloatRegister(Symbol *symbol);

  // Get temponary register, which rotates
  MRegisterType GetTempRegister();

  // Write back all registers and unassociate all symbols.
  void SpillAll();
private:
  StackFrameManager& sfm;
  AssemblerCode& ac;

  // Find the register associated with symbol and return its index
  // Returns -1 if not found
  int FindSymbol(Symbol *symbols[], int size, Symbol *symbol) const;

  // Find an unused register and returns its index
  // Returns -1 if not found
  int FindUnused(Symbol *symbols[], int size) const;

  int PickSpillRegister(MRegisterType registers[], int size) const;

  // Clears the symbol associated with the register and generates spill code
  void SpillIntRegister(int idx);
  void SpillFloatRegister(int idx);

  void GenerateIntSpillCode(MRegisterType reg, Symbol *symbol);
  void GenerateFloatSpillCode(MRegisterType reg, Symbol *symbol);

  void GenerateIntLoadCode(MRegisterType reg, Symbol *symbol);
  void GenerateFloatLoadCode(MRegisterType reg, Symbol *symbol);

  static const int int_reg_size = 18; // number of integer registers
  static MRegisterType int_registers[int_reg_size]; // the integer registers that can be used
  Symbol *int_symbols[int_reg_size]; // symbols associated with integer registers

  static const int float_reg_size = 15; // number of float registers
  static MRegisterType float_registers[float_reg_size]; // the float registers that can be used
  Symbol *float_symbols[float_reg_size]; // symbols associated with integer registers

  static const int tmp_reg_size = 4;
  static MRegisterType tmp_registers[tmp_reg_size];
};

#endif /* REGISTERMANAGER_H */