/*

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 * This code is free software; you can redistribute it and/or modify it

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 * 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.

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#include "code/vmreg.hpp"

#include "opto/optoreg.hpp"

// Some fun naming (textual) substitutions:

//

// RegMask::get_low_elem() ==> RegMask::find_first_elem()

// RegMask::Special        ==> RegMask::Empty

// RegMask::_flags         ==> RegMask::is_AllStack()

// RegMask::operator<<=()  ==> RegMask::Insert()

// RegMask::operator>>=()  ==> RegMask::Remove()

// RegMask::Union()        ==> RegMask::OR

// RegMask::Inter()        ==> RegMask::AND

//

// OptoRegister::RegName   ==> OptoReg::Name

//

// OptoReg::stack0()       ==> _last_Mach_Reg  or ZERO in core version

//

// numregs in chaitin      ==> proper degree in chaitin

//-------------Non-zero bit search methods used by RegMask---------------------

// Find lowest 1, or return 32 if empty

int find_lowest_bit( uint32_t mask );

// Find highest 1, or return 32 if empty

int find_hihghest_bit( uint32_t mask );

//------------------------------RegMask----------------------------------------

// The ADL file describes how to print the machine-specific registers, as well

// as any notion of register classes.  We provide a register mask, which is

// just a collection of Register numbers.

// The ADLC defines 2 macros, RM_SIZE and FORALL_BODY.

// RM_SIZE is the size of a register mask in words.

// FORALL_BODY replicates a BODY macro once per word in the register mask.

// The usage is somewhat clumsy and limited to the regmask.[h,c]pp files.

// However, it means the ADLC can redefine the unroll macro and all loops

// over register masks will be unrolled by the correct amount.

class RegMask {

  union {

    double _dummy_force_double_alignment[RM_SIZE>>1];

    // Array of Register Mask bits.  This array is large enough to cover

    // all the machine registers and all parameters that need to be passed

    // on the stack (stack registers) up to some interesting limit.  Methods

    // that need more parameters will NOT be compiled.  On Intel, the limit

    // is something like 90+ parameters.

    int _A[RM_SIZE];

  };

  enum {

    _WordBits    = BitsPerInt,

    _LogWordBits = LogBitsPerInt,

    _RM_SIZE     = RM_SIZE   // local constant, imported, then hidden by #undef

  };

public:

  enum { CHUNK_SIZE = RM_SIZE*_WordBits };

  // SlotsPerLong is 2, since slots are 32 bits and longs are 64 bits.

  // Also, consider the maximum alignment size for a normally allocated

  // value.  Since we allocate register pairs but not register quads (at

  // present), this alignment is SlotsPerLong (== 2).  A normally

  // aligned allocated register is either a single register, or a pair

  // of adjacent registers, the lower-numbered being even.

  // See also is_aligned_Pairs() below, and the padding added before

  // Matcher::_new_SP to keep allocated pairs aligned properly.

  // If we ever go to quad-word allocations, SlotsPerQuad will become

  // the controlling alignment constraint.  Note that this alignment

  // requirement is internal to the allocator, and independent of any

  // particular platform.

  enum { SlotsPerLong = 2,

         SlotsPerVecS = 1,

         SlotsPerVecD = 2,

         SlotsPerVecX = 4,

         SlotsPerVecY = 8,

         SlotsPerVecZ = 16 };

  // A constructor only used by the ADLC output.  All mask fields are filled

  // in directly.  Calls to this look something like RM(1,2,3,4);

  RegMask(

#   define BODY(I) int a##I,

    FORALL_BODY

#   undef BODY

    int dummy = 0 ) {

#   define BODY(I) _A[I] = a##I;

    FORALL_BODY

#   undef BODY

  }

  // Handy copying constructor

  RegMask( RegMask *rm ) {

#   define BODY(I) _A[I] = rm->_A[I];

    FORALL_BODY

#   undef BODY

  }

  // Construct an empty mask

  RegMask( ) { Clear(); }

  // Construct a mask with a single bit

  RegMask( OptoReg::Name reg ) { Clear(); Insert(reg); }

  // Check for register being in mask

  int Member( OptoReg::Name reg ) const {

    assert( reg < CHUNK_SIZE, "" );

    return _A[reg>>_LogWordBits] & (1<<(reg&(_WordBits-1)));

  }

  // The last bit in the register mask indicates that the mask should repeat

  // indefinitely with ONE bits.  Returns TRUE if mask is infinite or

  // unbounded in size.  Returns FALSE if mask is finite size.

  int is_AllStack() const { return _A[RM_SIZE-1] >> (_WordBits-1); }

  // Work around an -xO3 optimization problme in WS6U1. The old way:

  //   void set_AllStack() { _A[RM_SIZE-1] |= (1<<(_WordBits-1)); }

  // will cause _A[RM_SIZE-1] to be clobbered, not updated when set_AllStack()

  // follows an Insert() loop, like the one found in init_spill_mask(). Using

  // Insert() instead works because the index into _A in computed instead of

  // constant.  See bug 4665841.

  void set_AllStack() { Insert(OptoReg::Name(CHUNK_SIZE-1)); }

  // Test for being a not-empty mask.

  int is_NotEmpty( ) const {

    int tmp = 0;

#   define BODY(I) tmp |= _A[I];

    FORALL_BODY

#   undef BODY

    return tmp;

  }

  // Find lowest-numbered register from mask, or BAD if mask is empty.

  OptoReg::Name find_first_elem() const {

    int base, bits;

#   define BODY(I) if( (bits = _A[I]) != 0 ) base = I<<_LogWordBits; else

    FORALL_BODY

#   undef BODY

      { base = OptoReg::Bad; bits = 1<<0; }

    return OptoReg::Name(base + find_lowest_bit(bits));

  }

  // Get highest-numbered register from mask, or BAD if mask is empty.

  OptoReg::Name find_last_elem() const {

    int base, bits;

#   define BODY(I) if( (bits = _A[RM_SIZE-1-I]) != 0 ) base = (RM_SIZE-1-I)<<_LogWordBits; else

    FORALL_BODY

#   undef BODY

      { base = OptoReg::Bad; bits = 1<<0; }

    return OptoReg::Name(base + find_hihghest_bit(bits));

  }

  // Find the lowest-numbered register pair in the mask.  Return the

  // HIGHEST register number in the pair, or BAD if no pairs.

  // Assert that the mask contains only bit pairs.

  OptoReg::Name find_first_pair() const;

  // Clear out partial bits; leave only aligned adjacent bit pairs.

  void clear_to_pairs();

  // Smear out partial bits; leave only aligned adjacent bit pairs.

  void smear_to_pairs();

  // Verify that the mask contains only aligned adjacent bit pairs

  void verify_pairs() const { assert( is_aligned_pairs(), "mask is not aligned, adjacent pairs" ); }

  // Test that the mask contains only aligned adjacent bit pairs

  bool is_aligned_pairs() const;

  // mask is a pair of misaligned registers

  bool is_misaligned_pair() const { return Size()==2 && !is_aligned_pairs(); }

  // Test for single register

  int is_bound1() const;

  // Test for a single adjacent pair

  int is_bound_pair() const;

  // Test for a single adjacent set of ideal register's size.

  int is_bound(uint ireg) const {

    if (is_vector(ireg)) {

      if (is_bound_set(num_registers(ireg)))

        return true;

    } else if (is_bound1() || is_bound_pair()) {

      return true;

    }

    return false;

  }

  // Find the lowest-numbered register set in the mask.  Return the

  // HIGHEST register number in the set, or BAD if no sets.

  // Assert that the mask contains only bit sets.

  OptoReg::Name find_first_set(const int size) const;

  // Clear out partial bits; leave only aligned adjacent bit sets of size.

  void clear_to_sets(const int size);

  // Smear out partial bits to aligned adjacent bit sets.

  void smear_to_sets(const int size);

  // Verify that the mask contains only aligned adjacent bit sets

  void verify_sets(int size) const { assert(is_aligned_sets(size), "mask is not aligned, adjacent sets"); }

  // Test that the mask contains only aligned adjacent bit sets

  bool is_aligned_sets(const int size) const;

  // mask is a set of misaligned registers

  bool is_misaligned_set(int size) const { return (int)Size()==size && !is_aligned_sets(size);}

  // Test for a single adjacent set

  int is_bound_set(const int size) const;

  static bool is_vector(uint ireg);

  static int num_registers(uint ireg);

  // Fast overlap test.  Non-zero if any registers in common.

  int overlap( const RegMask &rm ) const {

    return

#   define BODY(I) (_A[I] & rm._A[I]) |

    FORALL_BODY

#   undef BODY

    0 ;

  }

  // Special test for register pressure based splitting

  // UP means register only, Register plus stack, or stack only is DOWN

  bool is_UP() const;

  // Clear a register mask

  void Clear( ) {

#   define BODY(I) _A[I] = 0;

    FORALL_BODY

#   undef BODY

  }

  // Fill a register mask with 1's

  void Set_All( ) {

#   define BODY(I) _A[I] = -1;

    FORALL_BODY

#   undef BODY

  }

  // Insert register into mask

  void Insert( OptoReg::Name reg ) {

    assert( reg < CHUNK_SIZE, "" );

    _A[reg>>_LogWordBits] |= (1<<(reg&(_WordBits-1)));

  }

  // Remove register from mask

  void Remove( OptoReg::Name reg ) {

    assert( reg < CHUNK_SIZE, "" );

    _A[reg>>_LogWordBits] &= ~(1<<(reg&(_WordBits-1)));

  }

  // OR 'rm' into 'this'

  void OR( const RegMask &rm ) {

#   define BODY(I) this->_A[I] |= rm._A[I];

    FORALL_BODY

#   undef BODY

  }

  // AND 'rm' into 'this'

  void AND( const RegMask &rm ) {

#   define BODY(I) this->_A[I] &= rm._A[I];

    FORALL_BODY

#   undef BODY

  }

  // Subtract 'rm' from 'this'

  void SUBTRACT( const RegMask &rm ) {

#   define BODY(I) _A[I] &= ~rm._A[I];

    FORALL_BODY

#   undef BODY

  }

  // Compute size of register mask: number of bits

  uint Size() const;

#ifndef PRODUCT

  void print() const { dump(); }

  void dump(outputStream *st = tty) const; // Print a mask

#endif

  static const RegMask Empty;   // Common empty mask

  static bool can_represent(OptoReg::Name reg) {

    // NOTE: -1 in computation reflects the usage of the last

    //       bit of the regmask as an infinite stack flag and

    //       -7 is to keep mask aligned for largest value (VecZ).

    return (int)reg < (int)(CHUNK_SIZE-1);

  }

  static bool can_represent_arg(OptoReg::Name reg) {

    // NOTE: -SlotsPerVecZ in computation reflects the need

    //       to keep mask aligned for largest value (VecZ).

    return (int)reg < (int)(CHUNK_SIZE-SlotsPerVecZ);

  }

};

// Do not use this constant directly in client code!

#undef RM_SIZE