libcpp/:

[pf3gnuchains/gcc-fork.git] / gcc / ira-costs.c

/* IRA hard register and memory cost calculation for allocnos.
   Copyright (C) 2006, 2007, 2008, 2009
   Free Software Foundation, Inc.
   Contributed by Vladimir Makarov <vmakarov@redhat.com>.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC 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
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "hard-reg-set.h"
#include "rtl.h"
#include "expr.h"
#include "tm_p.h"
#include "flags.h"
#include "basic-block.h"
#include "regs.h"
#include "addresses.h"
#include "insn-config.h"
#include "recog.h"
#include "toplev.h"
#include "target.h"
#include "params.h"
#include "ira-int.h"

/* The file contains code is similar to one in regclass but the code
   works on the allocno basis.  */

#ifdef FORBIDDEN_INC_DEC_CLASSES
/* Indexed by n, is TRUE if allocno with number N is used in an
   auto-inc or auto-dec context.  */
static bool *in_inc_dec;
#endif

/* The `costs' struct records the cost of using hard registers of each
   class considered for the calculation and of using memory for each
   allocno.  */
struct costs
{
  int mem_cost;
  /* Costs for register classes start here.  We process only some
     register classes (cover classes on the 1st cost calculation
     iteration and important classes on the 2nd iteration).  */
  int cost[1];
};

/* Initialized once.  It is a maximal possible size of the allocated
   struct costs.  */
static int max_struct_costs_size;

/* Allocated and initialized once, and used to initialize cost values
   for each insn.  */
static struct costs *init_cost;

/* Allocated once, and used for temporary purposes.  */
static struct costs *temp_costs;

/* Allocated once, and used for the cost calculation.  */
static struct costs *op_costs[MAX_RECOG_OPERANDS];
static struct costs *this_op_costs[MAX_RECOG_OPERANDS];

/* Original and accumulated costs of each class for each allocno.  */
static struct costs *allocno_costs, *total_costs;

/* Classes used for cost calculation.  They may be different on
   different iterations of the cost calculations or in different
   optimization modes.  */
static enum reg_class *cost_classes;

/* The size of the previous array.  */
static int cost_classes_num;

/* Map: cost class -> order number (they start with 0) of the cost
   class.  The order number is negative for non-cost classes.  */
static int cost_class_nums[N_REG_CLASSES];

/* It is the current size of struct costs.  */
static int struct_costs_size;

/* Return pointer to structure containing costs of allocno with given
   NUM in array ARR.  */
#define COSTS_OF_ALLOCNO(arr, num) \
  ((struct costs *) ((char *) (arr) + (num) * struct_costs_size))

/* Record register class preferences of each allocno.  Null value
   means no preferences.  It happens on the 1st iteration of the cost
   calculation.  */
static enum reg_class *allocno_pref;

/* Allocated buffers for allocno_pref.  */
static enum reg_class *allocno_pref_buffer;

/* Record register class of each allocno with the same regno.  */
static enum reg_class *common_classes;

/* Execution frequency of the current insn.  */
static int frequency;

\f

/* Compute the cost of loading X into (if TO_P is TRUE) or from (if
   TO_P is FALSE) a register of class RCLASS in mode MODE.  X must not
   be a pseudo register.  */
static int
copy_cost (rtx x, enum machine_mode mode, enum reg_class rclass, bool to_p,
           secondary_reload_info *prev_sri)
{
  secondary_reload_info sri;
  enum reg_class secondary_class = NO_REGS;

  /* If X is a SCRATCH, there is actually nothing to move since we are
     assuming optimal allocation.  */
  if (GET_CODE (x) == SCRATCH)
    return 0;

  /* Get the class we will actually use for a reload.  */
  rclass = PREFERRED_RELOAD_CLASS (x, rclass);

  /* If we need a secondary reload for an intermediate, the cost is
     that to load the input into the intermediate register, then to
     copy it.  */
  sri.prev_sri = prev_sri;
  sri.extra_cost = 0;
  secondary_class = targetm.secondary_reload (to_p, x, rclass, mode, &sri);

  if (secondary_class != NO_REGS)
    {
      if (!move_cost[mode])
        init_move_cost (mode);
      return (move_cost[mode][secondary_class][rclass] + sri.extra_cost
              + copy_cost (x, mode, secondary_class, to_p, &sri));
    }

  /* For memory, use the memory move cost, for (hard) registers, use
     the cost to move between the register classes, and use 2 for
     everything else (constants).  */
  if (MEM_P (x) || rclass == NO_REGS)
    return sri.extra_cost + ira_memory_move_cost[mode][rclass][to_p != 0];
  else if (REG_P (x))
    {
      if (!move_cost[mode])
        init_move_cost (mode);
      return (sri.extra_cost + move_cost[mode][REGNO_REG_CLASS (REGNO (x))][rclass]);
    }
  else
    /* If this is a constant, we may eventually want to call rtx_cost
       here.  */
    return sri.extra_cost + COSTS_N_INSNS (1);
}

\f

/* Record the cost of using memory or hard registers of various
   classes for the operands in INSN.

   N_ALTS is the number of alternatives.
   N_OPS is the number of operands.
   OPS is an array of the operands.
   MODES are the modes of the operands, in case any are VOIDmode.
   CONSTRAINTS are the constraints to use for the operands.  This array
   is modified by this procedure.

   This procedure works alternative by alternative.  For each
   alternative we assume that we will be able to allocate all allocnos
   to their ideal register class and calculate the cost of using that
   alternative.  Then we compute, for each operand that is a
   pseudo-register, the cost of having the allocno allocated to each
   register class and using it in that alternative.  To this cost is
   added the cost of the alternative.

   The cost of each class for this insn is its lowest cost among all
   the alternatives.  */
static void
record_reg_classes (int n_alts, int n_ops, rtx *ops,
                    enum machine_mode *modes, const char **constraints,
                    rtx insn, struct costs **op_costs,
                    enum reg_class *allocno_pref)
{
  int alt;
  int i, j, k;
  rtx set;
  int insn_allows_mem[MAX_RECOG_OPERANDS];

  for (i = 0; i < n_ops; i++)
    insn_allows_mem[i] = 0;

  /* Process each alternative, each time minimizing an operand's cost
     with the cost for each operand in that alternative.  */
  for (alt = 0; alt < n_alts; alt++)
    {
      enum reg_class classes[MAX_RECOG_OPERANDS];
      int allows_mem[MAX_RECOG_OPERANDS];
      enum reg_class rclass;
      int alt_fail = 0;
      int alt_cost = 0, op_cost_add;

      for (i = 0; i < n_ops; i++)
        {
          unsigned char c;
          const char *p = constraints[i];
          rtx op = ops[i];
          enum machine_mode mode = modes[i];
          int allows_addr = 0;
          int win = 0;

          /* Initially show we know nothing about the register class.  */
          classes[i] = NO_REGS;
          allows_mem[i] = 0;

          /* If this operand has no constraints at all, we can
             conclude nothing about it since anything is valid.  */
          if (*p == 0)
            {
              if (REG_P (op) && REGNO (op) >= FIRST_PSEUDO_REGISTER)
                memset (this_op_costs[i], 0, struct_costs_size);
              continue;
            }

          /* If this alternative is only relevant when this operand
             matches a previous operand, we do different things
             depending on whether this operand is a allocno-reg or not.
             We must process any modifiers for the operand before we
             can make this test.  */
          while (*p == '%' || *p == '=' || *p == '+' || *p == '&')
            p++;

          if (p[0] >= '0' && p[0] <= '0' + i && (p[1] == ',' || p[1] == 0))
            {
              /* Copy class and whether memory is allowed from the
                 matching alternative.  Then perform any needed cost
                 computations and/or adjustments.  */
              j = p[0] - '0';
              classes[i] = classes[j];
              allows_mem[i] = allows_mem[j];
              if (allows_mem[i])
                insn_allows_mem[i] = 1;

              if (! REG_P (op) || REGNO (op) < FIRST_PSEUDO_REGISTER)
                {
                  /* If this matches the other operand, we have no
                     added cost and we win.  */
                  if (rtx_equal_p (ops[j], op))
                    win = 1;
                  /* If we can put the other operand into a register,
                     add to the cost of this alternative the cost to
                     copy this operand to the register used for the
                     other operand.  */
                  else if (classes[j] != NO_REGS)
                    {
                      alt_cost += copy_cost (op, mode, classes[j], 1, NULL);
                      win = 1;
                    }
                }
              else if (! REG_P (ops[j])
                       || REGNO (ops[j]) < FIRST_PSEUDO_REGISTER)
                {
                  /* This op is an allocno but the one it matches is
                     not.  */

                  /* If we can't put the other operand into a
                     register, this alternative can't be used.  */

                  if (classes[j] == NO_REGS)
                    alt_fail = 1;
                  /* Otherwise, add to the cost of this alternative
                     the cost to copy the other operand to the hard
                     register used for this operand.  */
                  else
                    alt_cost += copy_cost (ops[j], mode, classes[j], 1, NULL);
                }
              else
                {
                  /* The costs of this operand are not the same as the
                     other operand since move costs are not symmetric.
                     Moreover, if we cannot tie them, this alternative
                     needs to do a copy, which is one insn.  */
                  struct costs *pp = this_op_costs[i];

                  for (k = 0; k < cost_classes_num; k++)
                    {
                      rclass = cost_classes[k];
                      pp->cost[k]
                        = (((recog_data.operand_type[i] != OP_OUT
                             ? ira_get_may_move_cost (mode, rclass,
                                                      classes[i], true) : 0)
                            + (recog_data.operand_type[i] != OP_IN
                               ? ira_get_may_move_cost (mode, classes[i],
                                                        rclass, false) : 0))
                           * frequency);
                    }

                  /* If the alternative actually allows memory, make
                     things a bit cheaper since we won't need an extra
                     insn to load it.  */
                  pp->mem_cost
                    = ((recog_data.operand_type[i] != OP_IN
                        ? ira_memory_move_cost[mode][classes[i]][0] : 0)
                       + (recog_data.operand_type[i] != OP_OUT
                          ? ira_memory_move_cost[mode][classes[i]][1] : 0)
                       - allows_mem[i]) * frequency;

                  /* If we have assigned a class to this allocno in our
                     first pass, add a cost to this alternative
                     corresponding to what we would add if this allocno
                     were not in the appropriate class.  We could use
                     cover class here but it is less accurate
                     approximation.  */
                  if (allocno_pref)
                    {
                      enum reg_class pref_class
                        = allocno_pref[ALLOCNO_NUM
                                       (ira_curr_regno_allocno_map
                                        [REGNO (op)])];

                      if (pref_class == NO_REGS)
                        alt_cost
                          += ((recog_data.operand_type[i] != OP_IN
                               ? ira_memory_move_cost[mode][classes[i]][0]
                               : 0)
                              + (recog_data.operand_type[i] != OP_OUT
                                 ? ira_memory_move_cost[mode][classes[i]][1]
                                 : 0));
                      else if (ira_reg_class_intersect
                               [pref_class][classes[i]] == NO_REGS)
                        alt_cost += ira_get_register_move_cost (mode,
                                                                pref_class,
                                                                classes[i]);
                    }
                  if (REGNO (ops[i]) != REGNO (ops[j])
                      && ! find_reg_note (insn, REG_DEAD, op))
                    alt_cost += 2;

                  /* This is in place of ordinary cost computation for
                     this operand, so skip to the end of the
                     alternative (should be just one character).  */
                  while (*p && *p++ != ',')
                    ;

                  constraints[i] = p;
                  continue;
                }
            }
          
          /* Scan all the constraint letters.  See if the operand
             matches any of the constraints.  Collect the valid
             register classes and see if this operand accepts
             memory.  */
          while ((c = *p))
            {
              switch (c)
                {
                case ',':
                  break;
                case '*':
                  /* Ignore the next letter for this pass.  */
                  c = *++p;
                  break;

                case '?':
                  alt_cost += 2;
                case '!':  case '#':  case '&':
                case '0':  case '1':  case '2':  case '3':  case '4':
                case '5':  case '6':  case '7':  case '8':  case '9':
                  break;

                case 'p':
                  allows_addr = 1;
                  win = address_operand (op, GET_MODE (op));
                  /* We know this operand is an address, so we want it
                     to be allocated to a register that can be the
                     base of an address, i.e. BASE_REG_CLASS.  */
                  classes[i]
                    = ira_reg_class_union[classes[i]]
                      [base_reg_class (VOIDmode, ADDRESS, SCRATCH)];
                  break;

                case 'm':  case 'o':  case 'V':
                  /* It doesn't seem worth distinguishing between
                     offsettable and non-offsettable addresses
                     here.  */
                  insn_allows_mem[i] = allows_mem[i] = 1;
                  if (MEM_P (op))
                    win = 1;
                  break;

                case '<':
                  if (MEM_P (op)
                      && (GET_CODE (XEXP (op, 0)) == PRE_DEC
                          || GET_CODE (XEXP (op, 0)) == POST_DEC))
                    win = 1;
                  break;

                case '>':
                  if (MEM_P (op)
                      && (GET_CODE (XEXP (op, 0)) == PRE_INC
                          || GET_CODE (XEXP (op, 0)) == POST_INC))
                    win = 1;
                  break;

                case 'E':
                case 'F':
                  if (GET_CODE (op) == CONST_DOUBLE
                      || (GET_CODE (op) == CONST_VECTOR
                          && (GET_MODE_CLASS (GET_MODE (op))
                              == MODE_VECTOR_FLOAT)))
                    win = 1;
                  break;

                case 'G':
                case 'H':
                  if (GET_CODE (op) == CONST_DOUBLE
                      && CONST_DOUBLE_OK_FOR_CONSTRAINT_P (op, c, p))
                    win = 1;
                  break;

                case 's':
                  if (GET_CODE (op) == CONST_INT
                      || (GET_CODE (op) == CONST_DOUBLE
                          && GET_MODE (op) == VOIDmode))
                    break;

                case 'i':
                  if (CONSTANT_P (op)
                      && (! flag_pic || LEGITIMATE_PIC_OPERAND_P (op)))
                    win = 1;
                  break;

                case 'n':
                  if (GET_CODE (op) == CONST_INT
                      || (GET_CODE (op) == CONST_DOUBLE
                          && GET_MODE (op) == VOIDmode))
                    win = 1;
                  break;

                case 'I':
                case 'J':
                case 'K':
                case 'L':
                case 'M':
                case 'N':
                case 'O':
                case 'P':
                  if (GET_CODE (op) == CONST_INT
                      && CONST_OK_FOR_CONSTRAINT_P (INTVAL (op), c, p))
                    win = 1;
                  break;

                case 'X':
                  win = 1;
                  break;

                case 'g':
                  if (MEM_P (op)
                      || (CONSTANT_P (op)
                          && (! flag_pic || LEGITIMATE_PIC_OPERAND_P (op))))
                    win = 1;
                  insn_allows_mem[i] = allows_mem[i] = 1;
                case 'r':
                  classes[i] = ira_reg_class_union[classes[i]][GENERAL_REGS];
                  break;

                default:
                  if (REG_CLASS_FROM_CONSTRAINT (c, p) != NO_REGS)
                    classes[i] = ira_reg_class_union[classes[i]]
                                 [REG_CLASS_FROM_CONSTRAINT (c, p)];
#ifdef EXTRA_CONSTRAINT_STR
                  else if (EXTRA_CONSTRAINT_STR (op, c, p))
                    win = 1;

                  if (EXTRA_MEMORY_CONSTRAINT (c, p))
                    {
                      /* Every MEM can be reloaded to fit.  */
                      insn_allows_mem[i] = allows_mem[i] = 1;
                      if (MEM_P (op))
                        win = 1;
                    }
                  if (EXTRA_ADDRESS_CONSTRAINT (c, p))
                    {
                      /* Every address can be reloaded to fit.  */
                      allows_addr = 1;
                      if (address_operand (op, GET_MODE (op)))
                        win = 1;
                      /* We know this operand is an address, so we
                         want it to be allocated to a hard register
                         that can be the base of an address,
                         i.e. BASE_REG_CLASS.  */
                      classes[i]
                        = ira_reg_class_union[classes[i]]
                          [base_reg_class (VOIDmode, ADDRESS, SCRATCH)];
                    }
#endif
                  break;
                }
              p += CONSTRAINT_LEN (c, p);
              if (c == ',')
                break;
            }

          constraints[i] = p;

          /* How we account for this operand now depends on whether it
             is a pseudo register or not.  If it is, we first check if
             any register classes are valid.  If not, we ignore this
             alternative, since we want to assume that all allocnos get
             allocated for register preferencing.  If some register
             class is valid, compute the costs of moving the allocno
             into that class.  */
          if (REG_P (op) && REGNO (op) >= FIRST_PSEUDO_REGISTER)
            {
              if (classes[i] == NO_REGS)
                {
                  /* We must always fail if the operand is a REG, but
                     we did not find a suitable class.

                     Otherwise we may perform an uninitialized read
                     from this_op_costs after the `continue' statement
                     below.  */
                  alt_fail = 1;
                }
              else
                {
                  struct costs *pp = this_op_costs[i];

                  for (k = 0; k < cost_classes_num; k++)
                    {
                      rclass = cost_classes[k];
                      pp->cost[k]
                        = (((recog_data.operand_type[i] != OP_OUT
                             ? ira_get_may_move_cost (mode, rclass,
                                                      classes[i], true) : 0)
                            + (recog_data.operand_type[i] != OP_IN
                               ? ira_get_may_move_cost (mode, classes[i],
                                                        rclass, false) : 0))
                           * frequency);
                    }

                  /* If the alternative actually allows memory, make
                     things a bit cheaper since we won't need an extra
                     insn to load it.  */
                  pp->mem_cost
                    = ((recog_data.operand_type[i] != OP_IN
                        ? ira_memory_move_cost[mode][classes[i]][0] : 0)
                       + (recog_data.operand_type[i] != OP_OUT
                          ? ira_memory_move_cost[mode][classes[i]][1] : 0)
                       - allows_mem[i]) * frequency;
                  /* If we have assigned a class to this allocno in our
                     first pass, add a cost to this alternative
                     corresponding to what we would add if this allocno
                     were not in the appropriate class.  We could use
                     cover class here but it is less accurate
                     approximation.  */
                  if (allocno_pref)
                    {
                      enum reg_class pref_class
                        = allocno_pref[ALLOCNO_NUM
                                       (ira_curr_regno_allocno_map
                                        [REGNO (op)])];

                      if (pref_class == NO_REGS)
                        alt_cost
                          += ((recog_data.operand_type[i] != OP_IN
                               ? ira_memory_move_cost[mode][classes[i]][0]
                               : 0)
                              + (recog_data.operand_type[i] != OP_OUT
                                 ? ira_memory_move_cost[mode][classes[i]][1]
                                 : 0));
                      else if (ira_reg_class_intersect[pref_class][classes[i]]
                               == NO_REGS)
                        alt_cost += ira_get_register_move_cost (mode,
                                                                pref_class,
                                                                classes[i]);
                    }
                }
            }

          /* Otherwise, if this alternative wins, either because we
             have already determined that or if we have a hard
             register of the proper class, there is no cost for this
             alternative.  */
          else if (win || (REG_P (op)
                           && reg_fits_class_p (op, classes[i],
                                                0, GET_MODE (op))))
            ;

          /* If registers are valid, the cost of this alternative
             includes copying the object to and/or from a
             register.  */
          else if (classes[i] != NO_REGS)
            {
              if (recog_data.operand_type[i] != OP_OUT)
                alt_cost += copy_cost (op, mode, classes[i], 1, NULL);

              if (recog_data.operand_type[i] != OP_IN)
                alt_cost += copy_cost (op, mode, classes[i], 0, NULL);
            }
          /* The only other way this alternative can be used is if
             this is a constant that could be placed into memory.  */
          else if (CONSTANT_P (op) && (allows_addr || allows_mem[i]))
            alt_cost += ira_memory_move_cost[mode][classes[i]][1];
          else
            alt_fail = 1;
        }

      if (alt_fail)
        continue;

      op_cost_add = alt_cost * frequency;
      /* Finally, update the costs with the information we've
         calculated about this alternative.  */
      for (i = 0; i < n_ops; i++)
        if (REG_P (ops[i]) && REGNO (ops[i]) >= FIRST_PSEUDO_REGISTER)
          {
            struct costs *pp = op_costs[i], *qq = this_op_costs[i];
            int scale = 1 + (recog_data.operand_type[i] == OP_INOUT);

            pp->mem_cost = MIN (pp->mem_cost,
                                (qq->mem_cost + op_cost_add) * scale);

            for (k = 0; k < cost_classes_num; k++)
              pp->cost[k]
                = MIN (pp->cost[k], (qq->cost[k] + op_cost_add) * scale);
          }
    }

  for (i = 0; i < n_ops; i++)
    {
      ira_allocno_t a;
      rtx op = ops[i];

      if (! REG_P (op) || REGNO (op) < FIRST_PSEUDO_REGISTER)
        continue;
      a = ira_curr_regno_allocno_map [REGNO (op)];
      if (! ALLOCNO_BAD_SPILL_P (a) && insn_allows_mem[i] == 0)
        ALLOCNO_BAD_SPILL_P (a) = true;
    }

  /* If this insn is a single set copying operand 1 to operand 0 and
     one operand is an allocno with the other a hard reg or an allocno
     that prefers a hard register that is in its own register class
     then we may want to adjust the cost of that register class to -1.

     Avoid the adjustment if the source does not die to avoid
     stressing of register allocator by preferrencing two colliding
     registers into single class.

     Also avoid the adjustment if a copy between hard registers of the
     class is expensive (ten times the cost of a default copy is
     considered arbitrarily expensive).  This avoids losing when the
     preferred class is very expensive as the source of a copy
     instruction.  */
  if ((set = single_set (insn)) != 0
      && ops[0] == SET_DEST (set) && ops[1] == SET_SRC (set)
      && REG_P (ops[0]) && REG_P (ops[1])
      && find_regno_note (insn, REG_DEAD, REGNO (ops[1])))
    for (i = 0; i <= 1; i++)
      if (REGNO (ops[i]) >= FIRST_PSEUDO_REGISTER)
        {
          unsigned int regno = REGNO (ops[!i]);
          enum machine_mode mode = GET_MODE (ops[!i]);
          enum reg_class rclass;
          unsigned int nr;

          if (regno < FIRST_PSEUDO_REGISTER)
            for (k = 0; k < cost_classes_num; k++)
              {
                rclass = cost_classes[k];
                if (TEST_HARD_REG_BIT (reg_class_contents[rclass], regno)
                    && (reg_class_size[rclass]
                        == (unsigned) CLASS_MAX_NREGS (rclass, mode)))
                  {
                    if (reg_class_size[rclass] == 1)
                      op_costs[i]->cost[k] = -frequency;
                    else
                      {
                        for (nr = 0;
                             nr < (unsigned) hard_regno_nregs[regno][mode];
                             nr++)
                          if (! TEST_HARD_REG_BIT (reg_class_contents[rclass],
                                                   regno + nr))
                            break;
                        
                        if (nr == (unsigned) hard_regno_nregs[regno][mode])
                          op_costs[i]->cost[k] = -frequency;
                      }
                  }
              }
        }
}

\f

/* Wrapper around REGNO_OK_FOR_INDEX_P, to allow pseudo registers.  */
static inline bool
ok_for_index_p_nonstrict (rtx reg)
{
  unsigned regno = REGNO (reg);

  return regno >= FIRST_PSEUDO_REGISTER || REGNO_OK_FOR_INDEX_P (regno);
}

/* A version of regno_ok_for_base_p for use here, when all
   pseudo-registers should count as OK.  Arguments as for
   regno_ok_for_base_p.  */
static inline bool
ok_for_base_p_nonstrict (rtx reg, enum machine_mode mode,
                         enum rtx_code outer_code, enum rtx_code index_code)
{
  unsigned regno = REGNO (reg);

  if (regno >= FIRST_PSEUDO_REGISTER)
    return true;
  return ok_for_base_p_1 (regno, mode, outer_code, index_code);
}

/* Record the pseudo registers we must reload into hard registers in a
   subexpression of a memory address, X.

   If CONTEXT is 0, we are looking at the base part of an address,
   otherwise we are looking at the index part.

   MODE is the mode of the memory reference; OUTER_CODE and INDEX_CODE
   give the context that the rtx appears in.  These three arguments
   are passed down to base_reg_class.

   SCALE is twice the amount to multiply the cost by (it is twice so
   we can represent half-cost adjustments).  */
static void
record_address_regs (enum machine_mode mode, rtx x, int context,
                     enum rtx_code outer_code, enum rtx_code index_code,
                     int scale)
{
  enum rtx_code code = GET_CODE (x);
  enum reg_class rclass;

  if (context == 1)
    rclass = INDEX_REG_CLASS;
  else
    rclass = base_reg_class (mode, outer_code, index_code);

  switch (code)
    {
    case CONST_INT:
    case CONST:
    case CC0:
    case PC:
    case SYMBOL_REF:
    case LABEL_REF:
      return;

    case PLUS:
      /* When we have an address that is a sum, we must determine
         whether registers are "base" or "index" regs.  If there is a
         sum of two registers, we must choose one to be the "base".
         Luckily, we can use the REG_POINTER to make a good choice
         most of the time.  We only need to do this on machines that
         can have two registers in an address and where the base and
         index register classes are different.

         ??? This code used to set REGNO_POINTER_FLAG in some cases,
         but that seems bogus since it should only be set when we are
         sure the register is being used as a pointer.  */
      {
        rtx arg0 = XEXP (x, 0);
        rtx arg1 = XEXP (x, 1);
        enum rtx_code code0 = GET_CODE (arg0);
        enum rtx_code code1 = GET_CODE (arg1);

        /* Look inside subregs.  */
        if (code0 == SUBREG)
          arg0 = SUBREG_REG (arg0), code0 = GET_CODE (arg0);
        if (code1 == SUBREG)
          arg1 = SUBREG_REG (arg1), code1 = GET_CODE (arg1);

        /* If this machine only allows one register per address, it
           must be in the first operand.  */
        if (MAX_REGS_PER_ADDRESS == 1)
          record_address_regs (mode, arg0, 0, PLUS, code1, scale);

        /* If index and base registers are the same on this machine,
           just record registers in any non-constant operands.  We
           assume here, as well as in the tests below, that all
           addresses are in canonical form.  */
        else if (INDEX_REG_CLASS == base_reg_class (VOIDmode, PLUS, SCRATCH))
          {
            record_address_regs (mode, arg0, context, PLUS, code1, scale);
            if (! CONSTANT_P (arg1))
              record_address_regs (mode, arg1, context, PLUS, code0, scale);
          }

        /* If the second operand is a constant integer, it doesn't
           change what class the first operand must be.  */
        else if (code1 == CONST_INT || code1 == CONST_DOUBLE)
          record_address_regs (mode, arg0, context, PLUS, code1, scale);
        /* If the second operand is a symbolic constant, the first
           operand must be an index register.  */
        else if (code1 == SYMBOL_REF || code1 == CONST || code1 == LABEL_REF)
          record_address_regs (mode, arg0, 1, PLUS, code1, scale);
        /* If both operands are registers but one is already a hard
           register of index or reg-base class, give the other the
           class that the hard register is not.  */
        else if (code0 == REG && code1 == REG
                 && REGNO (arg0) < FIRST_PSEUDO_REGISTER
                 && (ok_for_base_p_nonstrict (arg0, mode, PLUS, REG)
                     || ok_for_index_p_nonstrict (arg0)))
          record_address_regs (mode, arg1,
                               ok_for_base_p_nonstrict (arg0, mode, PLUS, REG)
                               ? 1 : 0,
                               PLUS, REG, scale);
        else if (code0 == REG && code1 == REG
                 && REGNO (arg1) < FIRST_PSEUDO_REGISTER
                 && (ok_for_base_p_nonstrict (arg1, mode, PLUS, REG)
                     || ok_for_index_p_nonstrict (arg1)))
          record_address_regs (mode, arg0,
                               ok_for_base_p_nonstrict (arg1, mode, PLUS, REG)
                               ? 1 : 0,
                               PLUS, REG, scale);
        /* If one operand is known to be a pointer, it must be the
           base with the other operand the index.  Likewise if the
           other operand is a MULT.  */
        else if ((code0 == REG && REG_POINTER (arg0)) || code1 == MULT)
          {
            record_address_regs (mode, arg0, 0, PLUS, code1, scale);
            record_address_regs (mode, arg1, 1, PLUS, code0, scale);
          }
        else if ((code1 == REG && REG_POINTER (arg1)) || code0 == MULT)
          {
            record_address_regs (mode, arg0, 1, PLUS, code1, scale);
            record_address_regs (mode, arg1, 0, PLUS, code0, scale);
          }
        /* Otherwise, count equal chances that each might be a base or
           index register.  This case should be rare.  */
        else
          {
            record_address_regs (mode, arg0, 0, PLUS, code1, scale / 2);
            record_address_regs (mode, arg0, 1, PLUS, code1, scale / 2);
            record_address_regs (mode, arg1, 0, PLUS, code0, scale / 2);
            record_address_regs (mode, arg1, 1, PLUS, code0, scale / 2);
          }
      }
      break;

      /* Double the importance of an allocno that is incremented or
         decremented, since it would take two extra insns if it ends
         up in the wrong place.  */
    case POST_MODIFY:
    case PRE_MODIFY:
      record_address_regs (mode, XEXP (x, 0), 0, code,
                           GET_CODE (XEXP (XEXP (x, 1), 1)), 2 * scale);
      if (REG_P (XEXP (XEXP (x, 1), 1)))
        record_address_regs (mode, XEXP (XEXP (x, 1), 1), 1, code, REG,
                             2 * scale);
      break;

    case POST_INC:
    case PRE_INC:
    case POST_DEC:
    case PRE_DEC:
      /* Double the importance of an allocno that is incremented or
         decremented, since it would take two extra insns if it ends
         up in the wrong place.  If the operand is a pseudo-register,
         show it is being used in an INC_DEC context.  */
#ifdef FORBIDDEN_INC_DEC_CLASSES
      if (REG_P (XEXP (x, 0))
          && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER)
        in_inc_dec[ALLOCNO_NUM (ira_curr_regno_allocno_map
                                [REGNO (XEXP (x, 0))])] = true;
#endif
      record_address_regs (mode, XEXP (x, 0), 0, code, SCRATCH, 2 * scale);
      break;

    case REG:
      {
        struct costs *pp;
        enum reg_class i;
        int k;

        if (REGNO (x) < FIRST_PSEUDO_REGISTER)
          break;

        ALLOCNO_BAD_SPILL_P (ira_curr_regno_allocno_map[REGNO (x)]) = true;
        pp = COSTS_OF_ALLOCNO (allocno_costs,
                               ALLOCNO_NUM (ira_curr_regno_allocno_map
                                            [REGNO (x)]));
        pp->mem_cost += (ira_memory_move_cost[Pmode][rclass][1] * scale) / 2;
        for (k = 0; k < cost_classes_num; k++)
          {
            i = cost_classes[k];
            pp->cost[k]
              += (ira_get_may_move_cost (Pmode, i, rclass, true) * scale) / 2;
          }
      }
      break;

    default:
      {
        const char *fmt = GET_RTX_FORMAT (code);
        int i;
        for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
          if (fmt[i] == 'e')
            record_address_regs (mode, XEXP (x, i), context, code, SCRATCH,
                                 scale);
      }
    }
}

\f

/* Calculate the costs of insn operands.  */
static void
record_operand_costs (rtx insn, struct costs **op_costs,
                      enum reg_class *allocno_pref)
{
  const char *constraints[MAX_RECOG_OPERANDS];
  enum machine_mode modes[MAX_RECOG_OPERANDS];
  int i;

  for (i = 0; i < recog_data.n_operands; i++)
    {
      constraints[i] = recog_data.constraints[i];
      modes[i] = recog_data.operand_mode[i];
    }

  /* If we get here, we are set up to record the costs of all the
     operands for this insn.  Start by initializing the costs.  Then
     handle any address registers.  Finally record the desired classes
     for any allocnos, doing it twice if some pair of operands are
     commutative.  */
  for (i = 0; i < recog_data.n_operands; i++)
    {
      memcpy (op_costs[i], init_cost, struct_costs_size);

      if (GET_CODE (recog_data.operand[i]) == SUBREG)
        recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);

      if (MEM_P (recog_data.operand[i]))
        record_address_regs (GET_MODE (recog_data.operand[i]),
                             XEXP (recog_data.operand[i], 0),
                             0, MEM, SCRATCH, frequency * 2);
      else if (constraints[i][0] == 'p'
               || EXTRA_ADDRESS_CONSTRAINT (constraints[i][0],
                                            constraints[i]))
        record_address_regs (VOIDmode, recog_data.operand[i], 0, ADDRESS,
                             SCRATCH, frequency * 2);
    }

  /* Check for commutative in a separate loop so everything will have
     been initialized.  We must do this even if one operand is a
     constant--see addsi3 in m68k.md.  */
  for (i = 0; i < (int) recog_data.n_operands - 1; i++)
    if (constraints[i][0] == '%')
      {
        const char *xconstraints[MAX_RECOG_OPERANDS];
        int j;

        /* Handle commutative operands by swapping the constraints.
           We assume the modes are the same.  */
        for (j = 0; j < recog_data.n_operands; j++)
          xconstraints[j] = constraints[j];

        xconstraints[i] = constraints[i+1];
        xconstraints[i+1] = constraints[i];
        record_reg_classes (recog_data.n_alternatives, recog_data.n_operands,
                            recog_data.operand, modes,
                            xconstraints, insn, op_costs, allocno_pref);
      }
  record_reg_classes (recog_data.n_alternatives, recog_data.n_operands,
                      recog_data.operand, modes,
                      constraints, insn, op_costs, allocno_pref);
}

\f

/* Process one insn INSN.  Scan it and record each time it would save
   code to put a certain allocnos in a certain class.  Return the last
   insn processed, so that the scan can be continued from there.  */
static rtx
scan_one_insn (rtx insn)
{
  enum rtx_code pat_code;
  rtx set, note;
  int i, k;

  if (!INSN_P (insn))
    return insn;

  pat_code = GET_CODE (PATTERN (insn));
  if (pat_code == USE || pat_code == CLOBBER || pat_code == ASM_INPUT
      || pat_code == ADDR_VEC || pat_code == ADDR_DIFF_VEC)
    return insn;

  set = single_set (insn);
  extract_insn (insn);

  /* If this insn loads a parameter from its stack slot, then it
     represents a savings, rather than a cost, if the parameter is
     stored in memory.  Record this fact.  */
  if (set != 0 && REG_P (SET_DEST (set)) && MEM_P (SET_SRC (set))
      && (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != NULL_RTX
      && MEM_P (XEXP (note, 0)))
    {
      enum reg_class cl = GENERAL_REGS;
      rtx reg = SET_DEST (set);
      int num = ALLOCNO_NUM (ira_curr_regno_allocno_map[REGNO (reg)]);

      if (allocno_pref)
        cl = allocno_pref[num];
      COSTS_OF_ALLOCNO (allocno_costs, num)->mem_cost
        -= ira_memory_move_cost[GET_MODE (reg)][cl][1] * frequency;
      record_address_regs (GET_MODE (SET_SRC (set)), XEXP (SET_SRC (set), 0),
                           0, MEM, SCRATCH, frequency * 2);
    }

  record_operand_costs (insn, op_costs, allocno_pref);

  /* Now add the cost for each operand to the total costs for its
     allocno.  */
  for (i = 0; i < recog_data.n_operands; i++)
    if (REG_P (recog_data.operand[i])
        && REGNO (recog_data.operand[i]) >= FIRST_PSEUDO_REGISTER)
      {
        int regno = REGNO (recog_data.operand[i]);
        struct costs *p
          = COSTS_OF_ALLOCNO (allocno_costs,
                              ALLOCNO_NUM (ira_curr_regno_allocno_map[regno]));
        struct costs *q = op_costs[i];

        p->mem_cost += q->mem_cost;
        for (k = 0; k < cost_classes_num; k++)
          p->cost[k] += q->cost[k];
      }

  return insn;
}

\f

/* Print allocnos costs to file F.  */
static void
print_costs (FILE *f)
{
  int k;
  ira_allocno_t a;
  ira_allocno_iterator ai;

  fprintf (f, "\n");
  FOR_EACH_ALLOCNO (a, ai)
    {
      int i, rclass;
      basic_block bb;
      int regno = ALLOCNO_REGNO (a);

      i = ALLOCNO_NUM (a);
      fprintf (f, "  a%d(r%d,", i, regno);
      if ((bb = ALLOCNO_LOOP_TREE_NODE (a)->bb) != NULL)
        fprintf (f, "b%d", bb->index);
      else
        fprintf (f, "l%d", ALLOCNO_LOOP_TREE_NODE (a)->loop->num);
      fprintf (f, ") costs:");
      for (k = 0; k < cost_classes_num; k++)
        {
          rclass = cost_classes[k];
          if (contains_reg_of_mode[rclass][PSEUDO_REGNO_MODE (regno)]
#ifdef FORBIDDEN_INC_DEC_CLASSES
              && (! in_inc_dec[i] || ! forbidden_inc_dec_class[rclass])
#endif
#ifdef CANNOT_CHANGE_MODE_CLASS
              && ! invalid_mode_change_p (regno, (enum reg_class) rclass,
                                          PSEUDO_REGNO_MODE (regno))
#endif
              )
            {
              fprintf (f, " %s:%d", reg_class_names[rclass],
                       COSTS_OF_ALLOCNO (allocno_costs, i)->cost[k]);
              if (flag_ira_region == IRA_REGION_ALL
                  || flag_ira_region == IRA_REGION_MIXED)
                fprintf (f, ",%d", COSTS_OF_ALLOCNO (total_costs, i)->cost[k]);
            }
        }
      fprintf (f, " MEM:%i\n", COSTS_OF_ALLOCNO (allocno_costs, i)->mem_cost);
    }
}

/* Traverse the BB represented by LOOP_TREE_NODE to update the allocno
   costs.  */
static void
process_bb_node_for_costs (ira_loop_tree_node_t loop_tree_node)
{
  basic_block bb;
  rtx insn;

  bb = loop_tree_node->bb;
  if (bb == NULL)
    return;
  frequency = REG_FREQ_FROM_BB (bb);
  if (frequency == 0)
    frequency = 1;
  FOR_BB_INSNS (bb, insn)
    insn = scan_one_insn (insn);
}

/* Find costs of register classes and memory for allocnos and their
   best costs. */
static void
find_allocno_class_costs (void)
{
  int i, k;
  int pass;
  basic_block bb;

  init_recog ();
#ifdef FORBIDDEN_INC_DEC_CLASSES
  in_inc_dec = ira_allocate (sizeof (bool) * ira_allocnos_num);
#endif /* FORBIDDEN_INC_DEC_CLASSES */
  allocno_pref = NULL;
  /* Normally we scan the insns once and determine the best class to
     use for each allocno.  However, if -fexpensive-optimizations are
     on, we do so twice, the second time using the tentative best
     classes to guide the selection.  */
  for (pass = 0; pass <= flag_expensive_optimizations; pass++)
    {
      if (internal_flag_ira_verbose > 0 && ira_dump_file)
        fprintf (ira_dump_file, "\nPass %i for finding allocno costs\n\n",
                 pass);
      /* We could use only cover classes.  Unfortunately it does not
         work well for some targets where some subclass of cover class
         is costly and wrong cover class is chosen.  */
      for (i = 0; i < N_REG_CLASSES; i++)
        cost_class_nums[i] = -1;
      for (cost_classes_num = 0;
           cost_classes_num < ira_important_classes_num;
           cost_classes_num++)
        {
          cost_classes[cost_classes_num]
            = ira_important_classes[cost_classes_num];
          cost_class_nums[cost_classes[cost_classes_num]]
            = cost_classes_num;
        }
      struct_costs_size
        = sizeof (struct costs) + sizeof (int) * (cost_classes_num - 1);
      /* Zero out our accumulation of the cost of each class for each
         allocno.  */
      memset (allocno_costs, 0, ira_allocnos_num * struct_costs_size);
#ifdef FORBIDDEN_INC_DEC_CLASSES
      memset (in_inc_dec, 0, ira_allocnos_num * sizeof (bool));
#endif

      /* Scan the instructions and record each time it would save code
         to put a certain allocno in a certain class.  */
      ira_traverse_loop_tree (true, ira_loop_tree_root,
                              process_bb_node_for_costs, NULL);

      memcpy (total_costs, allocno_costs,
              max_struct_costs_size * ira_allocnos_num);
      if (pass == 0)
        allocno_pref = allocno_pref_buffer;

      /* Now for each allocno look at how desirable each class is and
         find which class is preferred.  */
      for (i = max_reg_num () - 1; i >= FIRST_PSEUDO_REGISTER; i--)
        {
          ira_allocno_t a, parent_a;
          int rclass, a_num, parent_a_num;
          ira_loop_tree_node_t parent;
          int best_cost, allocno_cost;
          enum reg_class best, alt_class;
#ifdef FORBIDDEN_INC_DEC_CLASSES
          int inc_dec_p = false;
#endif

          if (ira_regno_allocno_map[i] == NULL)
            continue;
          memset (temp_costs, 0, struct_costs_size);
          /* Find cost of all allocnos with the same regno.  */
          for (a = ira_regno_allocno_map[i];
               a != NULL;
               a = ALLOCNO_NEXT_REGNO_ALLOCNO (a))
            {
              a_num = ALLOCNO_NUM (a);
              if ((flag_ira_region == IRA_REGION_ALL
                   || flag_ira_region == IRA_REGION_MIXED)
                  && (parent = ALLOCNO_LOOP_TREE_NODE (a)->parent) != NULL
                  && (parent_a = parent->regno_allocno_map[i]) != NULL
                  /* There are no caps yet.  */
                  && bitmap_bit_p (ALLOCNO_LOOP_TREE_NODE (a)->border_allocnos,
                                   ALLOCNO_NUM (a)))
                {
                  /* Propagate costs to upper levels in the region
                     tree.  */
                  parent_a_num = ALLOCNO_NUM (parent_a);
                  for (k = 0; k < cost_classes_num; k++)
                    COSTS_OF_ALLOCNO (total_costs, parent_a_num)->cost[k]
                      += COSTS_OF_ALLOCNO (total_costs, a_num)->cost[k];
                  COSTS_OF_ALLOCNO (total_costs, parent_a_num)->mem_cost
                    += COSTS_OF_ALLOCNO (total_costs, a_num)->mem_cost;
                }
              for (k = 0; k < cost_classes_num; k++)
                temp_costs->cost[k]
                  += COSTS_OF_ALLOCNO (allocno_costs, a_num)->cost[k];
              temp_costs->mem_cost
                += COSTS_OF_ALLOCNO (allocno_costs, a_num)->mem_cost;
#ifdef FORBIDDEN_INC_DEC_CLASSES
              if (in_inc_dec[a_num])
                inc_dec_p = true;
#endif
            }
          best_cost = (1 << (HOST_BITS_PER_INT - 2)) - 1;
          best = ALL_REGS;
          alt_class = NO_REGS;
          /* Find best common class for all allocnos with the same
             regno.  */
          for (k = 0; k < cost_classes_num; k++)
            {
              rclass = cost_classes[k];
              /* Ignore classes that are too small for this operand or
                 invalid for an operand that was auto-incremented.  */
              if (! contains_reg_of_mode[rclass][PSEUDO_REGNO_MODE (i)]
#ifdef FORBIDDEN_INC_DEC_CLASSES
                  || (inc_dec_p && forbidden_inc_dec_class[rclass])
#endif
#ifdef CANNOT_CHANGE_MODE_CLASS
                  || invalid_mode_change_p (i, (enum reg_class) rclass,
                                            PSEUDO_REGNO_MODE (i))
#endif
                  )
                continue;
              if (temp_costs->cost[k] < best_cost)
                {
                  best_cost = temp_costs->cost[k];
                  best = (enum reg_class) rclass;
                }
              else if (temp_costs->cost[k] == best_cost)
                best = ira_reg_class_union[best][rclass];
              if (pass == flag_expensive_optimizations
                  && temp_costs->cost[k] < temp_costs->mem_cost
                  && (reg_class_size[reg_class_subunion[alt_class][rclass]]
                      > reg_class_size[alt_class]))
                alt_class = reg_class_subunion[alt_class][rclass];
            }
          alt_class = ira_class_translate[alt_class];
          if (pass == flag_expensive_optimizations)
            {
              if (best_cost > temp_costs->mem_cost)
                best = alt_class = NO_REGS;
              else if (best == alt_class)
                alt_class = NO_REGS;
              setup_reg_classes (i, best, alt_class);
              if (internal_flag_ira_verbose > 2 && ira_dump_file != NULL)
                fprintf (ira_dump_file,
                         "    r%d: preferred %s, alternative %s\n",
                         i, reg_class_names[best], reg_class_names[alt_class]);
            }
          if (best_cost > temp_costs->mem_cost)
            common_classes[i] = NO_REGS;
          else if (flag_ira_algorithm == IRA_ALGORITHM_PRIORITY)
            /* Make the common class the biggest class of best and
               alt_class.  */
            common_classes[i] = alt_class == NO_REGS ? best : alt_class;
          else
            /* Make the common class a cover class.  Remember all
               allocnos with the same regno should have the same cover
               class.  */
            common_classes[i] = ira_class_translate[best];
          for (a = ira_regno_allocno_map[i];
               a != NULL;
               a = ALLOCNO_NEXT_REGNO_ALLOCNO (a))
            {
              a_num = ALLOCNO_NUM (a);
              if (common_classes[i] == NO_REGS)
                best = NO_REGS;
              else
                {             
                  /* Finding best class which is subset of the common
                     class.  */
                  best_cost = (1 << (HOST_BITS_PER_INT - 2)) - 1;
                  allocno_cost = best_cost;
                  best = ALL_REGS;
                  for (k = 0; k < cost_classes_num; k++)
                    {
                      rclass = cost_classes[k];
                      if (! ira_class_subset_p[rclass][common_classes[i]])
                        continue;
                      /* Ignore classes that are too small for this
                         operand or invalid for an operand that was
                         auto-incremented.  */
                      if (! contains_reg_of_mode[rclass][PSEUDO_REGNO_MODE (i)]
#ifdef FORBIDDEN_INC_DEC_CLASSES
                          || (inc_dec_p && forbidden_inc_dec_class[rclass])
#endif
#ifdef CANNOT_CHANGE_MODE_CLASS
                          || invalid_mode_change_p (i, (enum reg_class) rclass,
                                                    PSEUDO_REGNO_MODE (i))
#endif
                          )
                        ;
                      else if (COSTS_OF_ALLOCNO (total_costs, a_num)->cost[k]
                               < best_cost)
                        {
                          best_cost
                            = COSTS_OF_ALLOCNO (total_costs, a_num)->cost[k];
                          allocno_cost
                            = COSTS_OF_ALLOCNO (allocno_costs, a_num)->cost[k];
                          best = (enum reg_class) rclass;
                        }
                      else if (COSTS_OF_ALLOCNO (total_costs, a_num)->cost[k]
                               == best_cost)
                        {
                          best = ira_reg_class_union[best][rclass];
                          allocno_cost
                            = MAX (allocno_cost,
                                   COSTS_OF_ALLOCNO (allocno_costs,
                                                     a_num)->cost[k]);
                        }
                    }
                  ALLOCNO_COVER_CLASS_COST (a) = allocno_cost;
                }
              ira_assert (flag_ira_algorithm == IRA_ALGORITHM_PRIORITY
                          || ira_class_translate[best] == common_classes[i]);
              if (internal_flag_ira_verbose > 2 && ira_dump_file != NULL
                  && (pass == 0 || allocno_pref[a_num] != best))
                {
                  fprintf (ira_dump_file, "    a%d (r%d,", a_num, i);
                  if ((bb = ALLOCNO_LOOP_TREE_NODE (a)->bb) != NULL)
                    fprintf (ira_dump_file, "b%d", bb->index);
                  else
                    fprintf (ira_dump_file, "l%d",
                             ALLOCNO_LOOP_TREE_NODE (a)->loop->num);
                  fprintf (ira_dump_file, ") best %s, cover %s\n",
                           reg_class_names[best],
                           reg_class_names[common_classes[i]]);
                }
              allocno_pref[a_num] = best;
            }
        }
      
      if (internal_flag_ira_verbose > 4 && ira_dump_file)
        {
          print_costs (ira_dump_file);
          fprintf (ira_dump_file,"\n");
        }
    }
#ifdef FORBIDDEN_INC_DEC_CLASSES
  ira_free (in_inc_dec);
#endif
}

\f

/* Process moves involving hard regs to modify allocno hard register
   costs.  We can do this only after determining allocno cover class.
   If a hard register forms a register class, than moves with the hard
   register are already taken into account in class costs for the
   allocno.  */
static void
process_bb_node_for_hard_reg_moves (ira_loop_tree_node_t loop_tree_node)
{
  int i, freq, cost, src_regno, dst_regno, hard_regno;
  bool to_p;
  ira_allocno_t a;
  enum reg_class rclass, hard_reg_class;
  enum machine_mode mode;
  basic_block bb;
  rtx insn, set, src, dst;

  bb = loop_tree_node->bb;
  if (bb == NULL)
    return;
  freq = REG_FREQ_FROM_BB (bb);
  if (freq == 0)
    freq = 1;
  FOR_BB_INSNS (bb, insn)
    {
      if (! INSN_P (insn))
        continue;
      set = single_set (insn);
      if (set == NULL_RTX)
        continue;
      dst = SET_DEST (set);
      src = SET_SRC (set);
      if (! REG_P (dst) || ! REG_P (src))
        continue;
      dst_regno = REGNO (dst);
      src_regno = REGNO (src);
      if (dst_regno >= FIRST_PSEUDO_REGISTER
          && src_regno < FIRST_PSEUDO_REGISTER)
        {
          hard_regno = src_regno;
          to_p = true;
          a = ira_curr_regno_allocno_map[dst_regno];
        }
      else if (src_regno >= FIRST_PSEUDO_REGISTER
               && dst_regno < FIRST_PSEUDO_REGISTER)
        {
          hard_regno = dst_regno;
          to_p = false;
          a = ira_curr_regno_allocno_map[src_regno];
        }
      else
        continue;
      rclass = ALLOCNO_COVER_CLASS (a);
      if (! TEST_HARD_REG_BIT (reg_class_contents[rclass], hard_regno))
        continue;
      i = ira_class_hard_reg_index[rclass][hard_regno];
      if (i < 0)
        continue;
      mode = ALLOCNO_MODE (a);
      hard_reg_class = REGNO_REG_CLASS (hard_regno);
      cost
        = (to_p ? ira_get_register_move_cost (mode, hard_reg_class, rclass)
           : ira_get_register_move_cost (mode, rclass, hard_reg_class)) * freq;
      ira_allocate_and_set_costs (&ALLOCNO_HARD_REG_COSTS (a), rclass,
                                  ALLOCNO_COVER_CLASS_COST (a));
      ira_allocate_and_set_costs (&ALLOCNO_CONFLICT_HARD_REG_COSTS (a),
                                  rclass, 0);
      ALLOCNO_HARD_REG_COSTS (a)[i] -= cost;
      ALLOCNO_CONFLICT_HARD_REG_COSTS (a)[i] -= cost;
      ALLOCNO_COVER_CLASS_COST (a) = MIN (ALLOCNO_COVER_CLASS_COST (a),
                                          ALLOCNO_HARD_REG_COSTS (a)[i]);
    }
}

/* After we find hard register and memory costs for allocnos, define
   its cover class and modify hard register cost because insns moving
   allocno to/from hard registers.  */
static void
setup_allocno_cover_class_and_costs (void)
{
  int i, j, n, regno, num;
  int *reg_costs;
  enum reg_class cover_class, rclass;
  enum machine_mode mode;
  HARD_REG_SET *pref;
  ira_allocno_t a;
  ira_allocno_iterator ai;

  FOR_EACH_ALLOCNO (a, ai)
    {
      i = ALLOCNO_NUM (a);
      mode = ALLOCNO_MODE (a);
      cover_class = common_classes[ALLOCNO_REGNO (a)];
      ira_assert (allocno_pref[i] == NO_REGS || cover_class != NO_REGS);
      ALLOCNO_MEMORY_COST (a) = COSTS_OF_ALLOCNO (allocno_costs, i)->mem_cost;
      ira_set_allocno_cover_class (a, cover_class);
      if (cover_class == NO_REGS)
        continue;
      ALLOCNO_AVAILABLE_REGS_NUM (a) = ira_available_class_regs[cover_class];
      pref = &reg_class_contents[allocno_pref[i]];
      if (optimize && ALLOCNO_COVER_CLASS (a) != allocno_pref[i])
        {
          n = ira_class_hard_regs_num[cover_class];
          ALLOCNO_HARD_REG_COSTS (a)
            = reg_costs = ira_allocate_cost_vector (cover_class);
          for (j = n - 1; j >= 0; j--)
            {
              regno = ira_class_hard_regs[cover_class][j];
              if (TEST_HARD_REG_BIT (*pref, regno))
                reg_costs[j] = ALLOCNO_COVER_CLASS_COST (a);
              else
                {
                  rclass = REGNO_REG_CLASS (regno);
                  num = cost_class_nums[rclass];
                  if (num < 0)
                    {
                      /* The hard register class is not a cover class or a
                         class not fully inside in a cover class -- use
                         the allocno cover class.  */
                      ira_assert (ira_hard_regno_cover_class[regno]
                                  == cover_class);
                      num = cost_class_nums[cover_class];
                    }
                  reg_costs[j] = COSTS_OF_ALLOCNO (allocno_costs, i)->cost[num];
                }
            }
        }
    }
  if (optimize)
    ira_traverse_loop_tree (true, ira_loop_tree_root,
                            process_bb_node_for_hard_reg_moves, NULL);
}

\f

/* Function called once during compiler work.  */
void
ira_init_costs_once (void)
{
  int i;

  init_cost = NULL;
  for (i = 0; i < MAX_RECOG_OPERANDS; i++)
    {
      op_costs[i] = NULL;
      this_op_costs[i] = NULL;
    }
  temp_costs = NULL;
  cost_classes = NULL;
}

/* Free allocated temporary cost vectors.  */
static void
free_ira_costs (void)
{
  int i;

  if (init_cost != NULL)
    free (init_cost);
  init_cost = NULL;
  for (i = 0; i < MAX_RECOG_OPERANDS; i++)
    {
      if (op_costs[i] != NULL)
        free (op_costs[i]);
      if (this_op_costs[i] != NULL)
        free (this_op_costs[i]);
      op_costs[i] = this_op_costs[i] = NULL;
    }
  if (temp_costs != NULL)
    free (temp_costs);
  temp_costs = NULL;
  if (cost_classes != NULL)
    free (cost_classes);
  cost_classes = NULL;
}

/* This is called each time register related information is
   changed.  */
void
ira_init_costs (void)
{
  int i;

  free_ira_costs ();
  max_struct_costs_size
    = sizeof (struct costs) + sizeof (int) * (ira_important_classes_num - 1);
  /* Don't use ira_allocate because vectors live through several IRA calls.  */
  init_cost = (struct costs *) xmalloc (max_struct_costs_size);
  init_cost->mem_cost = 1000000;
  for (i = 0; i < ira_important_classes_num; i++)
    init_cost->cost[i] = 1000000;
  for (i = 0; i < MAX_RECOG_OPERANDS; i++)
    {
      op_costs[i] = (struct costs *) xmalloc (max_struct_costs_size);
      this_op_costs[i] = (struct costs *) xmalloc (max_struct_costs_size);
    }
  temp_costs = (struct costs *) xmalloc (max_struct_costs_size);
  cost_classes = (enum reg_class *) xmalloc (sizeof (enum reg_class)
                                             * ira_important_classes_num);
}

/* Function called once at the end of compiler work.  */
void
ira_finish_costs_once (void)
{
  free_ira_costs ();
}

\f

/* Entry function which defines cover class, memory and hard register
   costs for each allocno.  */
void
ira_costs (void)
{
  allocno_costs = (struct costs *) ira_allocate (max_struct_costs_size
                                               * ira_allocnos_num);
  total_costs = (struct costs *) ira_allocate (max_struct_costs_size
                                               * ira_allocnos_num);
  allocno_pref_buffer
    = (enum reg_class *) ira_allocate (sizeof (enum reg_class)
                                       * ira_allocnos_num);
  common_classes
    = (enum reg_class *) ira_allocate (sizeof (enum reg_class)
                                       * max_reg_num ());
  find_allocno_class_costs ();
  setup_allocno_cover_class_and_costs ();
  ira_free (common_classes);
  ira_free (allocno_pref_buffer);
  ira_free (total_costs);
  ira_free (allocno_costs);
}

\f

/* Change hard register costs for allocnos which lives through
   function calls.  This is called only when we found all intersected
   calls during building allocno live ranges.  */
void
ira_tune_allocno_costs_and_cover_classes (void)
{
  int j, n, regno;
  int cost, min_cost, *reg_costs;
  enum reg_class cover_class, rclass;
  enum machine_mode mode;
  ira_allocno_t a;
  ira_allocno_iterator ai;

  FOR_EACH_ALLOCNO (a, ai)
    {
      cover_class = ALLOCNO_COVER_CLASS (a);
      if (cover_class == NO_REGS)
        continue;
      mode = ALLOCNO_MODE (a);
      n = ira_class_hard_regs_num[cover_class];
      min_cost = INT_MAX;
      if (ALLOCNO_CALLS_CROSSED_NUM (a) != 0)
        {
          ira_allocate_and_set_costs
            (&ALLOCNO_HARD_REG_COSTS (a), cover_class,
             ALLOCNO_COVER_CLASS_COST (a));
          reg_costs = ALLOCNO_HARD_REG_COSTS (a);
          for (j = n - 1; j >= 0; j--)
            {
              regno = ira_class_hard_regs[cover_class][j];
              rclass = REGNO_REG_CLASS (regno);
              cost = 0;
              if (! ira_hard_reg_not_in_set_p (regno, mode, call_used_reg_set)
                  || HARD_REGNO_CALL_PART_CLOBBERED (regno, mode))
                cost += (ALLOCNO_CALL_FREQ (a)
                         * (ira_memory_move_cost[mode][rclass][0]
                            + ira_memory_move_cost[mode][rclass][1]));
#ifdef IRA_HARD_REGNO_ADD_COST_MULTIPLIER
              cost += ((ira_memory_move_cost[mode][rclass][0]
                        + ira_memory_move_cost[mode][rclass][1])
                       * ALLOCNO_FREQ (a)
                       * IRA_HARD_REGNO_ADD_COST_MULTIPLIER (regno) / 2);
#endif
              reg_costs[j] += cost;
              if (min_cost > reg_costs[j])
                min_cost = reg_costs[j];
            }
        }
      if (min_cost != INT_MAX)
        ALLOCNO_COVER_CLASS_COST (a) = min_cost;
    }
}