/*
 * Copyright 1998-2008 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 */

//------------------------------VMReg------------------------------------------
// The VM uses 'unwarped' stack slots; the compiler uses 'warped' stack slots.
// Register numbers below VMRegImpl::stack0 are the same for both.  Register
// numbers above stack0 are either warped (in the compiler) or unwarped
// (in the VM).  Unwarped numbers represent stack indices, offsets from
// the current stack pointer.  Warped numbers are required during compilation
// when we do not yet know how big the frame will be.

class VMRegImpl;
typedef VMRegImpl* VMReg;

class VMRegImpl {
// friend class OopMap;
friend class VMStructs;
friend class OptoReg;
// friend class Location;
private:
  enum {
    BAD = -1
  };



  static VMReg stack0;
  // Names for registers
  static const char *regName[];
  static const int register_count;


public:

  static VMReg  as_VMReg(int val, bool bad_ok = false) { assert(val > BAD || bad_ok, "invalid"); return (VMReg) (intptr_t) val; }

  const char*  name() {
    if (is_reg()) {
      return regName[value()];
    } else if (!is_valid()) {
      return "BAD";
    } else {
      // shouldn't really be called with stack
      return "STACKED REG";
    }
  }
  static VMReg Bad() { return (VMReg) (intptr_t) BAD; }
  bool is_valid() const { return ((intptr_t) this) != BAD; }
  bool is_stack() const { return (intptr_t) this >= (intptr_t) stack0; }
  bool is_reg()   const { return is_valid() && !is_stack(); }

  // A concrete register is a value that returns true for is_reg() and is
  // also a register you could use in the assembler. On machines with
  // 64bit registers only one half of the VMReg (and OptoReg) is considered
  // concrete.
  bool is_concrete();

  // VMRegs are 4 bytes wide on all platforms
  static const int stack_slot_size;
  static const int slots_per_word;


  // This really ought to check that the register is "real" in the sense that
  // we don't try and get the VMReg number of a physical register that doesn't
  // have an expressible part. That would be pd specific code
  VMReg next() {
    assert((is_reg() && value() < stack0->value() - 1) || is_stack(), "must be");
    return (VMReg)(intptr_t)(value() + 1);
  }
  VMReg prev() {
    assert((is_stack() && value() > stack0->value()) || (is_reg() && value() != 0), "must be");
    return (VMReg)(intptr_t)(value() - 1);
  }


  intptr_t value() const         {return (intptr_t) this; }

  void print_on(outputStream* st) const;
  void print() const { print_on(tty); }

  // bias a stack slot.
  // Typically used to adjust a virtual frame slots by amounts that are offset by
  // amounts that are part of the native abi. The VMReg must be a stack slot
  // and the result must be also.

  VMReg bias(int offset) {
    assert(is_stack(), "must be");
    // VMReg res = VMRegImpl::as_VMReg(value() + offset);
    VMReg res = stack2reg(reg2stack() + offset);
    assert(res->is_stack(), "must be");
    return res;
  }

  // Convert register numbers to stack slots and vice versa
  static VMReg stack2reg( int idx ) {
    return (VMReg) (intptr_t) (stack0->value() + idx);
  }

  uintptr_t reg2stack() {
    assert( is_stack(), "Not a stack-based register" );
    return value() - stack0->value();
  }

  static void set_regName();

#include "incls/_vmreg_pd.hpp.incl"

};

//---------------------------VMRegPair-------------------------------------------
// Pairs of 32-bit registers for arguments.
// SharedRuntime::java_calling_convention will overwrite the structs with
// the calling convention's registers.  VMRegImpl::Bad is returned for any
// unused 32-bit register.  This happens for the unused high half of Int
// arguments, or for 32-bit pointers or for longs in the 32-bit sparc build
// (which are passed to natives in low 32-bits of e.g. O0/O1 and the high
// 32-bits of O0/O1 are set to VMRegImpl::Bad).  Longs in one register & doubles
// always return a high and a low register, as do 64-bit pointers.
//
class VMRegPair {
private:
  VMReg _second;
  VMReg _first;
public:
  void set_bad (                   ) { _second=VMRegImpl::Bad(); _first=VMRegImpl::Bad(); }
  void set1    (         VMReg v  ) { _second=VMRegImpl::Bad(); _first=v; }
  void set2    (         VMReg v  ) { _second=v->next();  _first=v; }
  void set_pair( VMReg second, VMReg first    ) { _second= second;    _first= first; }
  void set_ptr ( VMReg ptr ) {
#ifdef _LP64
    _second = ptr->next();
#else
    _second = VMRegImpl::Bad();
#endif
    _first = ptr;
  }
  // Return true if single register, even if the pair is really just adjacent stack slots
  bool is_single_reg() const {
    return (_first->is_valid()) && (_first->value() + 1 == _second->value());
  }

  // Return true if single stack based "register" where the slot alignment matches input alignment
  bool is_adjacent_on_stack(int alignment) const {
    return (_first->is_stack() && (_first->value() + 1 == _second->value()) && ((_first->value() & (alignment-1)) == 0));
  }

  // Return true if single stack based "register" where the slot alignment matches input alignment
  bool is_adjacent_aligned_on_stack(int alignment) const {
    return (_first->is_stack() && (_first->value() + 1 == _second->value()) && ((_first->value() & (alignment-1)) == 0));
  }

  // Return true if single register but adjacent stack slots do not count
  bool is_single_phys_reg() const {
    return (_first->is_reg() && (_first->value() + 1 == _second->value()));
  }

  VMReg second() const { return _second; }
  VMReg first()  const { return _first; }
  VMRegPair(VMReg s, VMReg f) {  _second = s; _first = f; }
  VMRegPair(VMReg f) { _second = VMRegImpl::Bad(); _first = f; }
  VMRegPair() { _second = VMRegImpl::Bad(); _first = VMRegImpl::Bad(); }
};