[gcc.git] / gcc / reload.c

/* Search an insn for pseudo regs that must be in hard regs and are not.
   Copyright (C) 1987, 1988, 1989, 1992 Free Software Foundation, Inc.

This file is part of GNU CC.

GNU CC 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 2, or (at your option)
any later version.

GNU CC 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 GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


/* This file contains subroutines used only from the file reload1.c.
   It knows how to scan one insn for operands and values
   that need to be copied into registers to make valid code.
   It also finds other operands and values which are valid
   but for which equivalent values in registers exist and
   ought to be used instead.

   Before processing the first insn of the function, call `init_reload'.

   To scan an insn, call `find_reloads'.  This does two things:
   1. sets up tables describing which values must be reloaded
   for this insn, and what kind of hard regs they must be reloaded into;
   2. optionally record the locations where those values appear in
   the data, so they can be replaced properly later.
   This is done only if the second arg to `find_reloads' is nonzero.

   The third arg to `find_reloads' specifies the number of levels
   of indirect addressing supported by the machine.  If it is zero,
   indirect addressing is not valid.  If it is one, (MEM (REG n))
   is valid even if (REG n) did not get a hard register; if it is two,
   (MEM (MEM (REG n))) is also valid even if (REG n) did not get a
   hard register, and similarly for higher values.

   Then you must choose the hard regs to reload those pseudo regs into,
   and generate appropriate load insns before this insn and perhaps
   also store insns after this insn.  Set up the array `reload_reg_rtx'
   to contain the REG rtx's for the registers you used.  In some
   cases `find_reloads' will return a nonzero value in `reload_reg_rtx'
   for certain reloads.  Then that tells you which register to use,
   so you do not need to allocate one.  But you still do need to add extra
   instructions to copy the value into and out of that register.

   Finally you must call `subst_reloads' to substitute the reload reg rtx's
   into the locations already recorded.

NOTE SIDE EFFECTS:

   find_reloads can alter the operands of the instruction it is called on.

   1. Two operands of any sort may be interchanged, if they are in a
   commutative instruction.
   This happens only if find_reloads thinks the instruction will compile
   better that way.

   2. Pseudo-registers that are equivalent to constants are replaced
   with those constants if they are not in hard registers.

1 happens every time find_reloads is called.
2 happens only when REPLACE is 1, which is only when
actually doing the reloads, not when just counting them.


Using a reload register for several reloads in one insn:

When an insn has reloads, it is considered as having three parts:
the input reloads, the insn itself after reloading, and the output reloads.
Reloads of values used in memory addresses are often needed for only one part.

When this is so, reload_when_needed records which part needs the reload.
Two reloads for different parts of the insn can share the same reload
register.

When a reload is used for addresses in multiple parts, or when it is
an ordinary operand, it is classified as RELOAD_OTHER, and cannot share
a register with any other reload.  */

#define REG_OK_STRICT

#include "config.h"
#include "rtl.h"
#include "insn-config.h"
#include "insn-codes.h"
#include "recog.h"
#include "reload.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "flags.h"
#include "real.h"

#ifndef REGISTER_MOVE_COST
#define REGISTER_MOVE_COST(x, y) 2
#endif
\f
/* The variables set up by `find_reloads' are:

   n_reloads              number of distinct reloads needed; max reload # + 1
       tables indexed by reload number
   reload_in              rtx for value to reload from
   reload_out             rtx for where to store reload-reg afterward if nec
                           (often the same as reload_in)
   reload_reg_class       enum reg_class, saying what regs to reload into
   reload_inmode          enum machine_mode; mode this operand should have
                           when reloaded, on input.
   reload_outmode         enum machine_mode; mode this operand should have
                           when reloaded, on output.
   reload_strict_low      char; currently always zero; used to mean that this
                          reload is inside a STRICT_LOW_PART, but we don't
                          need to know this anymore.
   reload_optional        char, nonzero for an optional reload.
                           Optional reloads are ignored unless the
                           value is already sitting in a register.
   reload_inc             int, positive amount to increment or decrement by if
                           reload_in is a PRE_DEC, PRE_INC, POST_DEC, POST_INC.
                           Ignored otherwise (don't assume it is zero).
   reload_in_reg          rtx.  A reg for which reload_in is the equivalent.
                           If reload_in is a symbol_ref which came from
                           reg_equiv_constant, then this is the pseudo
                           which has that symbol_ref as equivalent.
   reload_reg_rtx         rtx.  This is the register to reload into.
                           If it is zero when `find_reloads' returns,
                           you must find a suitable register in the class
                           specified by reload_reg_class, and store here
                           an rtx for that register with mode from
                           reload_inmode or reload_outmode.
   reload_nocombine       char, nonzero if this reload shouldn't be
                           combined with another reload.
   reload_needed_for      rtx, operand this reload is needed for address of.
                           0 means it isn't needed for addressing.
   reload_needed_for_multiple
                          int, 1 if this reload needed for more than one thing.
   reload_when_needed     enum, classifies reload as needed either for
                           addressing an input reload, addressing an output,
                           for addressing a non-reloaded mem ref,
                           or for unspecified purposes (i.e., more than one
                           of the above).
   reload_secondary_reload int, gives the reload number of a secondary
                           reload, when needed; otherwise -1
   reload_secondary_p     int, 1 if this is a secondary register for one
                          or more reloads.
   reload_secondary_icode enum insn_code, if a secondary reload is required,
                           gives the INSN_CODE that uses the secondary
                           reload as a scratch register, or CODE_FOR_nothing
                           if the secondary reload register is to be an
                           intermediate register.  */
int n_reloads;

rtx reload_in[MAX_RELOADS];
rtx reload_out[MAX_RELOADS];
enum reg_class reload_reg_class[MAX_RELOADS];
enum machine_mode reload_inmode[MAX_RELOADS];
enum machine_mode reload_outmode[MAX_RELOADS];
char reload_strict_low[MAX_RELOADS];
rtx reload_reg_rtx[MAX_RELOADS];
char reload_optional[MAX_RELOADS];
int reload_inc[MAX_RELOADS];
rtx reload_in_reg[MAX_RELOADS];
char reload_nocombine[MAX_RELOADS];
int reload_needed_for_multiple[MAX_RELOADS];
rtx reload_needed_for[MAX_RELOADS];
enum reload_when_needed reload_when_needed[MAX_RELOADS];
int reload_secondary_reload[MAX_RELOADS];
int reload_secondary_p[MAX_RELOADS];
enum insn_code reload_secondary_icode[MAX_RELOADS];

/* All the "earlyclobber" operands of the current insn
   are recorded here.  */
int n_earlyclobbers;
rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];

/* Replacing reloads.

   If `replace_reloads' is nonzero, then as each reload is recorded
   an entry is made for it in the table `replacements'.
   Then later `subst_reloads' can look through that table and
   perform all the replacements needed.  */

/* Nonzero means record the places to replace.  */
static int replace_reloads;

/* Each replacement is recorded with a structure like this.  */
struct replacement
{
  rtx *where;                   /* Location to store in */
  rtx *subreg_loc;              /* Location of SUBREG if WHERE is inside
                                   a SUBREG; 0 otherwise.  */
  int what;                     /* which reload this is for */
  enum machine_mode mode;       /* mode it must have */
};

static struct replacement replacements[MAX_RECOG_OPERANDS * ((MAX_REGS_PER_ADDRESS * 2) + 1)];

/* Number of replacements currently recorded.  */
static int n_replacements;

/* MEM-rtx's created for pseudo-regs in stack slots not directly addressable;
   (see reg_equiv_address).  */
static rtx memlocs[MAX_RECOG_OPERANDS * ((MAX_REGS_PER_ADDRESS * 2) + 1)];
static int n_memlocs;

#ifdef SECONDARY_MEMORY_NEEDED

/* Save MEMs needed to copy from one class of registers to another.  One MEM
   is used per mode, but normally only one or two modes are ever used.  

   We keep two versions, before and after register elimination.  */

static rtx secondary_memlocs[NUM_MACHINE_MODES];
static rtx secondary_memlocs_elim[NUM_MACHINE_MODES];
#endif

/* The instruction we are doing reloads for;
   so we can test whether a register dies in it.  */
static rtx this_insn;

/* Nonzero if this instruction is a user-specified asm with operands.  */
static int this_insn_is_asm;

/* If hard_regs_live_known is nonzero,
   we can tell which hard regs are currently live,
   at least enough to succeed in choosing dummy reloads.  */
static int hard_regs_live_known;

/* Indexed by hard reg number,
   element is nonegative if hard reg has been spilled.
   This vector is passed to `find_reloads' as an argument
   and is not changed here.  */
static short *static_reload_reg_p;

/* Set to 1 in subst_reg_equivs if it changes anything.  */
static int subst_reg_equivs_changed;

/* On return from push_reload, holds the reload-number for the OUT
   operand, which can be different for that from the input operand.  */
static int output_reloadnum;

static int alternative_allows_memconst ();
static rtx find_dummy_reload ();
static rtx find_reloads_toplev ();
static int find_reloads_address ();
static int find_reloads_address_1 ();
static void find_reloads_address_part ();
static int hard_reg_set_here_p ();
/* static rtx forget_volatility (); */
static rtx subst_reg_equivs ();
static rtx subst_indexed_address ();
void copy_replacements ();
rtx find_equiv_reg ();
static int find_inc_amount ();
\f
#ifdef HAVE_SECONDARY_RELOADS

/* Determine if any secondary reloads are needed for loading (if IN_P is
   non-zero) or storing (if IN_P is zero) X to or from a reload register of
   register class RELOAD_CLASS in mode RELOAD_MODE.

   Return the register class of a secondary reload register, or NO_REGS if
   none.  *PMODE is set to the mode that the register is required in.
   If the reload register is needed as a scratch register instead of an
   intermediate register, *PICODE is set to the insn_code of the insn to be
   used to load or store the primary reload register; otherwise *PICODE
   is set to CODE_FOR_nothing.

   In some cases (such as storing MQ into an external memory location on
   the RT), both an intermediate register and a scratch register.  In that
   case, *PICODE is set to CODE_FOR_nothing, the class for the intermediate
   register is returned, and the *PTERTIARY_... variables are set to describe
   the scratch register.  */

static enum reg_class
find_secondary_reload (x, reload_class, reload_mode, in_p, picode, pmode,
                      ptertiary_class, ptertiary_icode, ptertiary_mode)
     rtx x;
     enum reg_class reload_class;
     enum machine_mode reload_mode;
     int in_p;
     enum insn_code *picode;
     enum machine_mode *pmode;
     enum reg_class *ptertiary_class;
     enum insn_code *ptertiary_icode;
     enum machine_mode *ptertiary_mode;
{
  enum reg_class class = NO_REGS;
  enum machine_mode mode = reload_mode;
  enum insn_code icode = CODE_FOR_nothing;
  enum reg_class t_class = NO_REGS;
  enum machine_mode t_mode = VOIDmode;
  enum insn_code t_icode = CODE_FOR_nothing;

  /* If X is a pseudo-register that has an equivalent MEM (actually, if it
     is still a pseudo-register by now, it *must* have an equivalent MEM
     but we don't want to assume that), use that equivalent when seeing if
     a secondary reload is needed since whether or not a reload is needed
     might be sensitive to the form of the MEM.  */

  if (GET_CODE (x) == REG && REGNO (x) >= FIRST_PSEUDO_REGISTER
      && reg_equiv_mem[REGNO (x)] != 0)
    x = reg_equiv_mem[REGNO (x)];

#ifdef SECONDARY_INPUT_RELOAD_CLASS
  if (in_p)
    class = SECONDARY_INPUT_RELOAD_CLASS (reload_class, reload_mode, x);
#endif

#ifdef SECONDARY_OUTPUT_RELOAD_CLASS
  if (! in_p)
    class = SECONDARY_OUTPUT_RELOAD_CLASS (reload_class, reload_mode, x);
#endif

  /* If we don't need any secondary registers, go away; the rest of the
     values won't be used.  */
  if (class == NO_REGS)
    return NO_REGS;

  /* Get a possible insn to use.  If the predicate doesn't accept X, don't
     use the insn.  */

  icode = (in_p ? reload_in_optab[(int) reload_mode]
           : reload_out_optab[(int) reload_mode]);

  if (icode != CODE_FOR_nothing
      && insn_operand_predicate[(int) icode][in_p]
      && (! (insn_operand_predicate[(int) icode][in_p]) (x, reload_mode)))
    icode = CODE_FOR_nothing;

  /* If we will be using an insn, see if it can directly handle the reload
     register we will be using.  If it can, the secondary reload is for a
     scratch register.  If it can't, we will use the secondary reload for
     an intermediate register and require a tertiary reload for the scratch
     register.  */

  if (icode != CODE_FOR_nothing)
    {
      /* If IN_P is non-zero, the reload register will be the output in 
         operand 0.  If IN_P is zero, the reload register will be the input
         in operand 1.  Outputs should have an initial "=", which we must
         skip.  */

      char insn_letter = insn_operand_constraint[(int) icode][!in_p][in_p];
      enum reg_class insn_class
        = (insn_letter == 'r' ? GENERAL_REGS
           : REG_CLASS_FROM_LETTER (insn_letter));

      if (insn_class == NO_REGS
          || (in_p && insn_operand_constraint[(int) icode][!in_p][0] != '=')
          /* The scratch register's constraint must start with "=&".  */
          || insn_operand_constraint[(int) icode][2][0] != '='
          || insn_operand_constraint[(int) icode][2][1] != '&')
        abort ();

      if (reg_class_subset_p (reload_class, insn_class))
        mode = insn_operand_mode[(int) icode][2];
      else
        {
          char t_letter = insn_operand_constraint[(int) icode][2][2];
          class = insn_class;
          t_mode = insn_operand_mode[(int) icode][2];
          t_class = (t_letter == 'r' ? GENERAL_REGS
                     : REG_CLASS_FROM_LETTER (t_letter));
          t_icode = icode;
          icode = CODE_FOR_nothing;
        }
    }

  *pmode = mode;
  *picode = icode;
  *ptertiary_class = t_class;
  *ptertiary_mode = t_mode;
  *ptertiary_icode = t_icode;

  return class;
}
#endif /* HAVE_SECONDARY_RELOADS */
\f
#ifdef SECONDARY_MEMORY_NEEDED

/* Return a memory location that will be used to copy X in mode MODE.  
   If we haven't already made a location for this mode in this insn,
   call find_reloads_address on the location being returned.  */

rtx
get_secondary_mem (x, mode)
     rtx x;
     enum machine_mode mode;
{
  rtx loc;
  int mem_valid;

  /* If MODE is narrower than a word, widen it.  This is required because
     most machines that require these memory locations do not support
     short load and stores from all registers (e.g., FP registers).  We could
     possibly conditionalize this, but we lose nothing by doing the wider
     mode.  */

  if (GET_MODE_BITSIZE (mode) < BITS_PER_WORD)
    mode = mode_for_size (BITS_PER_WORD, GET_MODE_CLASS (mode), 0);

  /* If we already have made a MEM for this insn, return it.  */
  if (secondary_memlocs_elim[(int) mode] != 0)
    return secondary_memlocs_elim[(int) mode];

  /* If this is the first time we've tried to get a MEM for this mode, 
     allocate a new one.  `something_changed' in reload will get set
     by noticing that the frame size has changed.  */

  if (secondary_memlocs[(int) mode] == 0)
    secondary_memlocs[(int) mode]
      = assign_stack_local (mode, GET_MODE_SIZE (mode), 0);

  /* Get a version of the address doing any eliminations needed.  If that
     didn't give us a new MEM, make a new one if it isn't valid.  */

  loc = eliminate_regs (secondary_memlocs[(int) mode], 0, NULL_RTX);
  mem_valid = strict_memory_address_p (mode, XEXP (loc, 0));

  if (! mem_valid && loc == secondary_memlocs[(int) mode])
    loc = copy_rtx (loc);

  /* The only time the call below will do anything is if the stack
     offset is too large.  In that case IND_LEVELS doesn't matter, so we
     can just pass a zero.  */
  if (! mem_valid)
    find_reloads_address (mode, NULL_PTR, XEXP (loc, 0), &XEXP (loc, 0), x, 0);

  /* If the address was not valid to begin with, we can not save it, because
     there is no guarantee that the reloads needed to make it valid will
     occur before every use of this address.  */

  else
    secondary_memlocs_elim[(int) mode] = loc;

  return loc;
}

/* Clear any secondary memory locations we've made.  */

void
clear_secondary_mem ()
{
  int i;

  for (i = 0; i < NUM_MACHINE_MODES; i++)
    secondary_memlocs[i] = 0;
}
#endif /* SECONDARY_MEMORY_NEEDED */
\f
/* Record one (sometimes two) reload that needs to be performed.
   IN is an rtx saying where the data are to be found before this instruction.
   OUT says where they must be stored after the instruction.
   (IN is zero for data not read, and OUT is zero for data not written.)
   INLOC and OUTLOC point to the places in the instructions where
   IN and OUT were found.
   CLASS is a register class required for the reloaded data.
   INMODE is the machine mode that the instruction requires
   for the reg that replaces IN and OUTMODE is likewise for OUT.

   If IN is zero, then OUT's location and mode should be passed as
   INLOC and INMODE.

   STRICT_LOW is the 1 if there is a containing STRICT_LOW_PART rtx.

   OPTIONAL nonzero means this reload does not need to be performed:
   it can be discarded if that is more convenient.

   The return value is the reload-number for this reload.

   If both IN and OUT are nonzero, in some rare cases we might
   want to make two separate reloads.  (Actually we never do this now.)
   Therefore, the reload-number for OUT is stored in
   output_reloadnum when we return; the return value applies to IN.
   Usually (presently always), when IN and OUT are nonzero,
   the two reload-numbers are equal, but the caller should be careful to
   distinguish them.  */

static int
push_reload (in, out, inloc, outloc, class,
             inmode, outmode, strict_low, optional, needed_for)
     register rtx in, out;
     rtx *inloc, *outloc;
     enum reg_class class;
     enum machine_mode inmode, outmode;
     int strict_low;
     int optional;
     rtx needed_for;
{
  register int i;
  int dont_share = 0;
  rtx *in_subreg_loc = 0, *out_subreg_loc = 0;
  int secondary_reload = -1;
  enum insn_code secondary_icode = CODE_FOR_nothing;

  /* Compare two RTX's.  */
#define MATCHES(x, y) \
 (x == y || (x != 0 && (GET_CODE (x) == REG                             \
                        ? GET_CODE (y) == REG && REGNO (x) == REGNO (y) \
                        : rtx_equal_p (x, y) && ! side_effects_p (x))))

  /* INMODE and/or OUTMODE could be VOIDmode if no mode
     has been specified for the operand.  In that case,
     use the operand's mode as the mode to reload.  */
  if (inmode == VOIDmode && in != 0)
    inmode = GET_MODE (in);
  if (outmode == VOIDmode && out != 0)
    outmode = GET_MODE (out);

  /* If IN is a pseudo register everywhere-equivalent to a constant, and 
     it is not in a hard register, reload straight from the constant,
     since we want to get rid of such pseudo registers.
     Often this is done earlier, but not always in find_reloads_address.  */
  if (in != 0 && GET_CODE (in) == REG)
    {
      register int regno = REGNO (in);

      if (regno >= FIRST_PSEUDO_REGISTER && reg_renumber[regno] < 0
          && reg_equiv_constant[regno] != 0)
        in = reg_equiv_constant[regno];
    }

  /* Likewise for OUT.  Of course, OUT will never be equivalent to
     an actual constant, but it might be equivalent to a memory location
     (in the case of a parameter).  */
  if (out != 0 && GET_CODE (out) == REG)
    {
      register int regno = REGNO (out);

      if (regno >= FIRST_PSEUDO_REGISTER && reg_renumber[regno] < 0
          && reg_equiv_constant[regno] != 0)
        out = reg_equiv_constant[regno];
    }

  /* If we have a read-write operand with an address side-effect,
     change either IN or OUT so the side-effect happens only once.  */
  if (in != 0 && out != 0 && GET_CODE (in) == MEM && rtx_equal_p (in, out))
    {
      if (GET_CODE (XEXP (in, 0)) == POST_INC
          || GET_CODE (XEXP (in, 0)) == POST_DEC)
        in = gen_rtx (MEM, GET_MODE (in), XEXP (XEXP (in, 0), 0));
      if (GET_CODE (XEXP (in, 0)) == PRE_INC
          || GET_CODE (XEXP (in, 0)) == PRE_DEC)
        out = gen_rtx (MEM, GET_MODE (out), XEXP (XEXP (out, 0), 0));
    }

  /* If we are reloading a (SUBREG (MEM ...) ...) or (SUBREG constant ...),
     really reload just the inside expression in its own mode.
     If we have (SUBREG:M1 (REG:M2 ...) ...) with M1 wider than M2 and the
     register is a pseudo, this will become the same as the above case.
     Do the same for (SUBREG:M1 (REG:M2 ...) ...) for a hard register R where
     either M1 is not valid for R or M2 is wider than a word but we only
     need one word to store an M2-sized quantity in R.
     Note that the case of (SUBREG (CONST_INT...)...) is handled elsewhere;
     we can't handle it here because CONST_INT does not indicate a mode.

     Similarly, we must reload the inside expression if we have a
     STRICT_LOW_PART (presumably, in == out in the cas).

     Also reload the inner expression if it does not require a secondary
     reload but the SUBREG does.  */

  if (in != 0 && GET_CODE (in) == SUBREG
      && (GET_CODE (SUBREG_REG (in)) != REG
          || strict_low
          || (GET_CODE (SUBREG_REG (in)) == REG
              && REGNO (SUBREG_REG (in)) >= FIRST_PSEUDO_REGISTER
              && (GET_MODE_SIZE (inmode)
                  > GET_MODE_SIZE (GET_MODE (SUBREG_REG (in)))))
          || (GET_CODE (SUBREG_REG (in)) == REG
              && REGNO (SUBREG_REG (in)) < FIRST_PSEUDO_REGISTER
              && (! HARD_REGNO_MODE_OK (REGNO (SUBREG_REG (in)), inmode)
                  || (GET_MODE_SIZE (inmode) <= UNITS_PER_WORD
                      && (GET_MODE_SIZE (GET_MODE (SUBREG_REG (in)))
                          > UNITS_PER_WORD)
                      && ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (in)))
                           / UNITS_PER_WORD)
                          != HARD_REGNO_NREGS (REGNO (SUBREG_REG (in)),
                                               GET_MODE (SUBREG_REG (in)))))))
#ifdef SECONDARY_INPUT_RELOAD_CLASS
          || (SECONDARY_INPUT_RELOAD_CLASS (class, inmode, in) != NO_REGS
              && (SECONDARY_INPUT_RELOAD_CLASS (class,
                                                GET_MODE (SUBREG_REG (in)),
                                                SUBREG_REG (in))
                  == NO_REGS))
#endif
          ))
    {
      in_subreg_loc = inloc;
      inloc = &SUBREG_REG (in);
      in = *inloc;
      if (GET_CODE (in) == MEM)
        /* This is supposed to happen only for paradoxical subregs made by
           combine.c.  (SUBREG (MEM)) isn't supposed to occur other ways.  */
        if (GET_MODE_SIZE (GET_MODE (in)) > GET_MODE_SIZE (inmode))
          abort ();
      inmode = GET_MODE (in);
    }

  /* Similarly for paradoxical and problematical SUBREGs on the output.
     Note that there is no reason we need worry about the previous value
     of SUBREG_REG (out); even if wider than out,
     storing in a subreg is entitled to clobber it all
     (except in the case of STRICT_LOW_PART,
     and in that case the constraint should label it input-output.)  */
  if (out != 0 && GET_CODE (out) == SUBREG
      && (GET_CODE (SUBREG_REG (out)) != REG
          || strict_low
          || (GET_CODE (SUBREG_REG (out)) == REG
              && REGNO (SUBREG_REG (out)) >= FIRST_PSEUDO_REGISTER
              && (GET_MODE_SIZE (outmode)
                  > GET_MODE_SIZE (GET_MODE (SUBREG_REG (out)))))
          || (GET_CODE (SUBREG_REG (out)) == REG
              && REGNO (SUBREG_REG (out)) < FIRST_PSEUDO_REGISTER
              && (! HARD_REGNO_MODE_OK (REGNO (SUBREG_REG (out)), outmode)
                  || (GET_MODE_SIZE (outmode) <= UNITS_PER_WORD
                      && (GET_MODE_SIZE (GET_MODE (SUBREG_REG (out)))
                          > UNITS_PER_WORD)
                      && ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (out)))
                           / UNITS_PER_WORD)
                          != HARD_REGNO_NREGS (REGNO (SUBREG_REG (out)),
                                               GET_MODE (SUBREG_REG (out)))))))
#ifdef SECONDARY_OUTPUT_RELOAD_CLASS
          || (SECONDARY_OUTPUT_RELOAD_CLASS (class, outmode, out) != NO_REGS
              && (SECONDARY_OUTPUT_RELOAD_CLASS (class,
                                                 GET_MODE (SUBREG_REG (out)),
                                                 SUBREG_REG (out))
                  == NO_REGS))
#endif
          ))
    {
      out_subreg_loc = outloc;
      outloc = &SUBREG_REG (out);
      out = *outloc;
      if (GET_CODE (out) == MEM
          && GET_MODE_SIZE (GET_MODE (out)) > GET_MODE_SIZE (outmode))
        abort ();
      outmode = GET_MODE (out);
    }

  /* That's all we use STRICT_LOW for, so clear it.  At some point,
     we may want to get rid of reload_strict_low.  */
  strict_low = 0;

  /* If IN appears in OUT, we can't share any input-only reload for IN.  */
  if (in != 0 && out != 0 && GET_CODE (out) == MEM
      && (GET_CODE (in) == REG || GET_CODE (in) == MEM)
      && reg_overlap_mentioned_for_reload_p (in, XEXP (out, 0)))
    dont_share = 1;

  /* If IN is a SUBREG of a hard register, make a new REG.  This
     simplifies some of the cases below.  */

  if (in != 0 && GET_CODE (in) == SUBREG && GET_CODE (SUBREG_REG (in)) == REG
      && REGNO (SUBREG_REG (in)) < FIRST_PSEUDO_REGISTER)
    in = gen_rtx (REG, GET_MODE (in),
                  REGNO (SUBREG_REG (in)) + SUBREG_WORD (in));

  /* Similarly for OUT.  */
  if (out != 0 && GET_CODE (out) == SUBREG
      && GET_CODE (SUBREG_REG (out)) == REG
      && REGNO (SUBREG_REG (out)) < FIRST_PSEUDO_REGISTER)
    out = gen_rtx (REG, GET_MODE (out),
                  REGNO (SUBREG_REG (out)) + SUBREG_WORD (out));

  /* Narrow down the class of register wanted if that is
     desirable on this machine for efficiency.  */
  if (in != 0)
    class = PREFERRED_RELOAD_CLASS (in, class);

  /* Output reloads may need analagous treatment, different in detail.  */
#ifdef PREFERRED_OUTPUT_RELOAD_CLASS
  if (out != 0)
    class = PREFERRED_OUTPUT_RELOAD_CLASS (out, class);
#endif

  /* Make sure we use a class that can handle the actual pseudo
     inside any subreg.  For example, on the 386, QImode regs
     can appear within SImode subregs.  Although GENERAL_REGS
     can handle SImode, QImode needs a smaller class.  */
#ifdef LIMIT_RELOAD_CLASS
  if (in_subreg_loc)
    class = LIMIT_RELOAD_CLASS (inmode, class);
  else if (in != 0 && GET_CODE (in) == SUBREG)
    class = LIMIT_RELOAD_CLASS (GET_MODE (SUBREG_REG (in)), class);

  if (out_subreg_loc)
    class = LIMIT_RELOAD_CLASS (outmode, class);
  if (out != 0 && GET_CODE (out) == SUBREG)
    class = LIMIT_RELOAD_CLASS (GET_MODE (SUBREG_REG (out)), class);
#endif

  /* Verify that this class is at least possible for the mode that
     is specified.  */
  if (this_insn_is_asm)
    {
      enum machine_mode mode;
      if (GET_MODE_SIZE (inmode) > GET_MODE_SIZE (outmode))
        mode = inmode;
      else
        mode = outmode;
      if (mode == VOIDmode)
        {
          error_for_asm (this_insn, "cannot reload integer constant operand in `asm'");
          mode = word_mode;
          if (in != 0)
            inmode = word_mode;
          if (out != 0)
            outmode = word_mode;
        }
      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
        if (HARD_REGNO_MODE_OK (i, mode)
            && TEST_HARD_REG_BIT (reg_class_contents[(int) class], i))
          {
            int nregs = HARD_REGNO_NREGS (i, mode);

            int j;
            for (j = 1; j < nregs; j++)
              if (! TEST_HARD_REG_BIT (reg_class_contents[(int) class], i + j))
                break;
            if (j == nregs)
              break;
          }
      if (i == FIRST_PSEUDO_REGISTER)
        {
          error_for_asm (this_insn, "impossible register constraint in `asm'");
          class = ALL_REGS;
        }
    }

  if (class == NO_REGS)
    abort ();

  /* We can use an existing reload if the class is right
     and at least one of IN and OUT is a match
     and the other is at worst neutral.
     (A zero compared against anything is neutral.)  */
  for (i = 0; i < n_reloads; i++)
    if ((reg_class_subset_p (class, reload_reg_class[i])
         || reg_class_subset_p (reload_reg_class[i], class))
        && reload_strict_low[i] == strict_low
        /* If the existing reload has a register, it must fit our class.  */
        && (reload_reg_rtx[i] == 0
            || TEST_HARD_REG_BIT (reg_class_contents[(int) class],
                                  true_regnum (reload_reg_rtx[i])))
        && ((in != 0 && MATCHES (reload_in[i], in) && ! dont_share
             && (out == 0 || reload_out[i] == 0 || MATCHES (reload_out[i], out)))
            ||
            (out != 0 && MATCHES (reload_out[i], out)
             && (in == 0 || reload_in[i] == 0 || MATCHES (reload_in[i], in)))))
      break;

  /* Reloading a plain reg for input can match a reload to postincrement
     that reg, since the postincrement's value is the right value.
     Likewise, it can match a preincrement reload, since we regard
     the preincrementation as happening before any ref in this insn
     to that register.  */
  if (i == n_reloads)
    for (i = 0; i < n_reloads; i++)
      if ((reg_class_subset_p (class, reload_reg_class[i])
           || reg_class_subset_p (reload_reg_class[i], class))
          /* If the existing reload has a register, it must fit our class.  */
          && (reload_reg_rtx[i] == 0
              || TEST_HARD_REG_BIT (reg_class_contents[(int) class],
                                    true_regnum (reload_reg_rtx[i])))
          && reload_strict_low[i] == strict_low
          && out == 0 && reload_out[i] == 0 && reload_in[i] != 0
          && ((GET_CODE (in) == REG
               && (GET_CODE (reload_in[i]) == POST_INC
                   || GET_CODE (reload_in[i]) == POST_DEC
                   || GET_CODE (reload_in[i]) == PRE_INC
                   || GET_CODE (reload_in[i]) == PRE_DEC)
               && MATCHES (XEXP (reload_in[i], 0), in))
              ||
              (GET_CODE (reload_in[i]) == REG
               && (GET_CODE (in) == POST_INC
                   || GET_CODE (in) == POST_DEC
                   || GET_CODE (in) == PRE_INC
                   || GET_CODE (in) == PRE_DEC)
               && MATCHES (XEXP (in, 0), reload_in[i]))))
        {
          /* Make sure reload_in ultimately has the increment,
             not the plain register.  */
          if (GET_CODE (in) == REG)
            in = reload_in[i];
          break;
        }

  if (i == n_reloads)
    {
#ifdef HAVE_SECONDARY_RELOADS
      enum reg_class secondary_class = NO_REGS;
      enum reg_class secondary_out_class = NO_REGS;
      enum machine_mode secondary_mode = inmode;
      enum machine_mode secondary_out_mode = outmode;
      enum insn_code secondary_icode;
      enum insn_code secondary_out_icode = CODE_FOR_nothing;
      enum reg_class tertiary_class = NO_REGS;
      enum reg_class tertiary_out_class = NO_REGS;
      enum machine_mode tertiary_mode;
      enum machine_mode tertiary_out_mode;
      enum insn_code tertiary_icode;
      enum insn_code tertiary_out_icode = CODE_FOR_nothing;
      int tertiary_reload = -1;

      /* See if we need a secondary reload register to move between
         CLASS and IN or CLASS and OUT.  Get the modes and icodes to
         use for each of them if so.  */

#ifdef SECONDARY_INPUT_RELOAD_CLASS
      if (in != 0)
        secondary_class
          = find_secondary_reload (in, class, inmode, 1, &secondary_icode,
                                   &secondary_mode, &tertiary_class,
                                   &tertiary_icode, &tertiary_mode);
#endif

#ifdef SECONDARY_OUTPUT_RELOAD_CLASS
      if (out != 0 && GET_CODE (out) != SCRATCH)
        secondary_out_class
          = find_secondary_reload (out, class, outmode, 0,
                                   &secondary_out_icode, &secondary_out_mode,
                                   &tertiary_out_class, &tertiary_out_icode,
                                   &tertiary_out_mode);
#endif

      /* We can only record one secondary and one tertiary reload.  If both
         IN and OUT need secondary reloads, we can only make an in-out
         reload if neither need an insn and if the classes are compatible.  */

      if (secondary_class != NO_REGS && secondary_out_class != NO_REGS
          && reg_class_subset_p (secondary_out_class, secondary_class))
        secondary_class = secondary_out_class;

      if (secondary_class != NO_REGS && secondary_out_class != NO_REGS
          && (! reg_class_subset_p (secondary_class, secondary_out_class)
              || secondary_icode != CODE_FOR_nothing
              || secondary_out_icode != CODE_FOR_nothing))
        {
          push_reload (NULL_RTX, out, NULL_PTR, outloc, class,
                       VOIDmode, outmode, strict_low, optional, needed_for);
          out = 0;
          outloc = 0;
          outmode = VOIDmode;
        }

      /* If we need a secondary reload for OUT but not IN, copy the
         information.  */
      if (secondary_class == NO_REGS && secondary_out_class != NO_REGS)
        {
          secondary_class = secondary_out_class;
          secondary_icode = secondary_out_icode;
          tertiary_class = tertiary_out_class;
          tertiary_icode = tertiary_out_icode;
          tertiary_mode = tertiary_out_mode;
        }

      if (secondary_class != NO_REGS)
        {
          /* If we need a tertiary reload, see if we have one we can reuse
             or else make one.  */

          if (tertiary_class != NO_REGS)
            {
              for (tertiary_reload = 0; tertiary_reload < n_reloads;
                   tertiary_reload++)
                if (reload_secondary_p[tertiary_reload]
                    && (reg_class_subset_p (tertiary_class,
                                            reload_reg_class[tertiary_reload])
                        || reg_class_subset_p (reload_reg_class[tertiary_reload],
                                               tertiary_class))
                    && ((reload_inmode[tertiary_reload] == tertiary_mode)
                        || reload_inmode[tertiary_reload] == VOIDmode)
                    && ((reload_outmode[tertiary_reload] == tertiary_mode)
                        || reload_outmode[tertiary_reload] == VOIDmode)
                    && (reload_secondary_icode[tertiary_reload]
                        == CODE_FOR_nothing))
                    
                  {
                    if (tertiary_mode != VOIDmode)
                      reload_inmode[tertiary_reload] = tertiary_mode;
                    if (tertiary_out_mode != VOIDmode)
                      reload_outmode[tertiary_reload] = tertiary_mode;
                    if (reg_class_subset_p (tertiary_class,
                                            reload_reg_class[tertiary_reload]))
                      reload_reg_class[tertiary_reload] = tertiary_class;
                    if (reload_needed_for[tertiary_reload] != needed_for)
                      reload_needed_for_multiple[tertiary_reload] = 1;
                    reload_optional[tertiary_reload] &= optional;
                    reload_secondary_p[tertiary_reload] = 1;
                  }

              if (tertiary_reload == n_reloads)
                {
                  /* We need to make a new tertiary reload for this register
                     class.  */
                  reload_in[tertiary_reload] = reload_out[tertiary_reload] = 0;
                  reload_reg_class[tertiary_reload] = tertiary_class;
                  reload_inmode[tertiary_reload] = tertiary_mode;
                  reload_outmode[tertiary_reload] = tertiary_mode;
                  reload_reg_rtx[tertiary_reload] = 0;
                  reload_optional[tertiary_reload] = optional;
                  reload_inc[tertiary_reload] = 0;
                  reload_strict_low[tertiary_reload] = 0;
                  /* Maybe we could combine these, but it seems too tricky.  */
                  reload_nocombine[tertiary_reload] = 1;
                  reload_in_reg[tertiary_reload] = 0;
                  reload_needed_for[tertiary_reload] = needed_for;
                  reload_needed_for_multiple[tertiary_reload] = 0;
                  reload_secondary_reload[tertiary_reload] = -1;
                  reload_secondary_icode[tertiary_reload] = CODE_FOR_nothing;
                  reload_secondary_p[tertiary_reload] = 1;

                  n_reloads++;
                  i = n_reloads;
                }
            }

          /* See if we can reuse an existing secondary reload.  */
          for (secondary_reload = 0; secondary_reload < n_reloads;
               secondary_reload++)
            if (reload_secondary_p[secondary_reload]
                && (reg_class_subset_p (secondary_class,
                                        reload_reg_class[secondary_reload])
                    || reg_class_subset_p (reload_reg_class[secondary_reload],
                                           secondary_class))
                && ((reload_inmode[secondary_reload] == secondary_mode)
                    || reload_inmode[secondary_reload] == VOIDmode)
                && ((reload_outmode[secondary_reload] == secondary_out_mode)
                    || reload_outmode[secondary_reload] == VOIDmode)
                && reload_secondary_reload[secondary_reload] == tertiary_reload
                && reload_secondary_icode[secondary_reload] == tertiary_icode)
              {
                if (secondary_mode != VOIDmode)
                  reload_inmode[secondary_reload] = secondary_mode;
                if (secondary_out_mode != VOIDmode)
                  reload_outmode[secondary_reload] = secondary_out_mode;
                if (reg_class_subset_p (secondary_class,
                                        reload_reg_class[secondary_reload]))
                  reload_reg_class[secondary_reload] = secondary_class;
                if (reload_needed_for[secondary_reload] != needed_for)
                  reload_needed_for_multiple[secondary_reload] = 1;
                reload_optional[secondary_reload] &= optional;
                reload_secondary_p[secondary_reload] = 1;
              }

          if (secondary_reload == n_reloads)
            {
              /* We need to make a new secondary reload for this register
                 class.  */
              reload_in[secondary_reload] = reload_out[secondary_reload] = 0;
              reload_reg_class[secondary_reload] = secondary_class;
              reload_inmode[secondary_reload] = secondary_mode;
              reload_outmode[secondary_reload] = secondary_out_mode;
              reload_reg_rtx[secondary_reload] = 0;
              reload_optional[secondary_reload] = optional;
              reload_inc[secondary_reload] = 0;
              reload_strict_low[secondary_reload] = 0;
              /* Maybe we could combine these, but it seems too tricky.  */
              reload_nocombine[secondary_reload] = 1;
              reload_in_reg[secondary_reload] = 0;
              reload_needed_for[secondary_reload] = needed_for;
              reload_needed_for_multiple[secondary_reload] = 0;
              reload_secondary_reload[secondary_reload] = tertiary_reload;
              reload_secondary_icode[secondary_reload] = tertiary_icode;
              reload_secondary_p[secondary_reload] = 1;

              n_reloads++;
              i = n_reloads;

#ifdef SECONDARY_MEMORY_NEEDED
              /* If we need a memory location to copy between the two
                 reload regs, set it up now.  */

              if (in != 0 && secondary_icode == CODE_FOR_nothing
                  && SECONDARY_MEMORY_NEEDED (secondary_class, class, inmode))
                get_secondary_mem (in, inmode);

              if (out != 0 && secondary_icode == CODE_FOR_nothing
                  && SECONDARY_MEMORY_NEEDED (class, secondary_class, outmode))
                get_secondary_mem (out, outmode);
#endif
            }
        }
#endif

      /* We found no existing reload suitable for re-use.
         So add an additional reload.  */

      reload_in[i] = in;
      reload_out[i] = out;
      reload_reg_class[i] = class;
      reload_inmode[i] = inmode;
      reload_outmode[i] = outmode;
      reload_reg_rtx[i] = 0;
      reload_optional[i] = optional;
      reload_inc[i] = 0;
      reload_strict_low[i] = strict_low;
      reload_nocombine[i] = 0;
      reload_in_reg[i] = inloc ? *inloc : 0;
      reload_needed_for[i] = needed_for;
      reload_needed_for_multiple[i] = 0;
      reload_secondary_reload[i] = secondary_reload;
      reload_secondary_icode[i] = secondary_icode;
      reload_secondary_p[i] = 0;

      n_reloads++;

#ifdef SECONDARY_MEMORY_NEEDED
      /* If a memory location is needed for the copy, make one.  */
      if (in != 0 && GET_CODE (in) == REG
          && REGNO (in) < FIRST_PSEUDO_REGISTER
          && SECONDARY_MEMORY_NEEDED (REGNO_REG_CLASS (REGNO (in)),
                                     class, inmode))
        get_secondary_mem (in, inmode);

      if (out != 0 && GET_CODE (out) == REG
          && REGNO (out) < FIRST_PSEUDO_REGISTER
          && SECONDARY_MEMORY_NEEDED (class, REGNO_REG_CLASS (REGNO (out)),
                                      outmode))
        get_secondary_mem (out, outmode);
#endif
    }
  else
    {
      /* We are reusing an existing reload,
         but we may have additional information for it.
         For example, we may now have both IN and OUT
         while the old one may have just one of them.  */

      if (inmode != VOIDmode)
        reload_inmode[i] = inmode;
      if (outmode != VOIDmode)
        reload_outmode[i] = outmode;
      if (in != 0)
        reload_in[i] = in;
      if (out != 0)
        reload_out[i] = out;
      if (reg_class_subset_p (class, reload_reg_class[i]))
        reload_reg_class[i] = class;
      reload_optional[i] &= optional;
      if (reload_needed_for[i] != needed_for)
        reload_needed_for_multiple[i] = 1;
    }

  /* If the ostensible rtx being reload differs from the rtx found
     in the location to substitute, this reload is not safe to combine
     because we cannot reliably tell whether it appears in the insn.  */

  if (in != 0 && in != *inloc)
    reload_nocombine[i] = 1;

#if 0
  /* This was replaced by changes in find_reloads_address_1 and the new
     function inc_for_reload, which go with a new meaning of reload_inc.  */

  /* If this is an IN/OUT reload in an insn that sets the CC,
     it must be for an autoincrement.  It doesn't work to store
     the incremented value after the insn because that would clobber the CC.
     So we must do the increment of the value reloaded from,
     increment it, store it back, then decrement again.  */
  if (out != 0 && sets_cc0_p (PATTERN (this_insn)))
    {
      out = 0;
      reload_out[i] = 0;
      reload_inc[i] = find_inc_amount (PATTERN (this_insn), in);
      /* If we did not find a nonzero amount-to-increment-by,
         that contradicts the belief that IN is being incremented
         in an address in this insn.  */
      if (reload_inc[i] == 0)
        abort ();
    }
#endif

  /* If we will replace IN and OUT with the reload-reg,
     record where they are located so that substitution need
     not do a tree walk.  */

  if (replace_reloads)
    {
      if (inloc != 0)
        {
          register struct replacement *r = &replacements[n_replacements++];
          r->what = i;
          r->subreg_loc = in_subreg_loc;
          r->where = inloc;
          r->mode = inmode;
        }
      if (outloc != 0 && outloc != inloc)
        {
          register struct replacement *r = &replacements[n_replacements++];
          r->what = i;
          r->where = outloc;
          r->subreg_loc = out_subreg_loc;
          r->mode = outmode;
        }
    }

  /* If this reload is just being introduced and it has both
     an incoming quantity and an outgoing quantity that are
     supposed to be made to match, see if either one of the two
     can serve as the place to reload into.

     If one of them is acceptable, set reload_reg_rtx[i]
     to that one.  */

  if (in != 0 && out != 0 && in != out && reload_reg_rtx[i] == 0)
    {
      reload_reg_rtx[i] = find_dummy_reload (in, out, inloc, outloc,
                                             reload_reg_class[i], i);

      /* If the outgoing register already contains the same value
         as the incoming one, we can dispense with loading it.
         The easiest way to tell the caller that is to give a phony
         value for the incoming operand (same as outgoing one).  */
      if (reload_reg_rtx[i] == out
          && (GET_CODE (in) == REG || CONSTANT_P (in))
          && 0 != find_equiv_reg (in, this_insn, 0, REGNO (out),
                                  static_reload_reg_p, i, inmode))
        reload_in[i] = out;
    }

  /* If this is an input reload and the operand contains a register that
     dies in this insn and is used nowhere else, see if it is the right class
     to be used for this reload.  Use it if so.  (This occurs most commonly
     in the case of paradoxical SUBREGs and in-out reloads).  We cannot do
     this if it is also an output reload that mentions the register unless
     the output is a SUBREG that clobbers an entire register.

     Note that the operand might be one of the spill regs, if it is a
     pseudo reg and we are in a block where spilling has not taken place.
     But if there is no spilling in this block, that is OK.
     An explicitly used hard reg cannot be a spill reg.  */

  if (reload_reg_rtx[i] == 0 && in != 0)
    {
      rtx note;
      int regno;

      for (note = REG_NOTES (this_insn); note; note = XEXP (note, 1))
        if (REG_NOTE_KIND (note) == REG_DEAD
            && GET_CODE (XEXP (note, 0)) == REG
            && (regno = REGNO (XEXP (note, 0))) < FIRST_PSEUDO_REGISTER
            && reg_mentioned_p (XEXP (note, 0), in)
            && ! refers_to_regno_for_reload_p (regno,
                                               (regno
                                                + HARD_REGNO_NREGS (regno,
                                                                    inmode)),
                                               PATTERN (this_insn), inloc)
            && (in != out
                || (GET_CODE (in) == SUBREG
                    && (((GET_MODE_SIZE (GET_MODE (in)) + (UNITS_PER_WORD - 1))
                         / UNITS_PER_WORD)
                        == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (in)))
                             + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD))))
            /* Make sure the operand fits in the reg that dies.  */
            && GET_MODE_SIZE (inmode) <= GET_MODE_SIZE (GET_MODE (XEXP (note, 0)))
            && HARD_REGNO_MODE_OK (regno, inmode)
            && GET_MODE_SIZE (outmode) <= GET_MODE_SIZE (GET_MODE (XEXP (note, 0)))
            && HARD_REGNO_MODE_OK (regno, outmode)
            && TEST_HARD_REG_BIT (reg_class_contents[(int) class], regno)
            && !fixed_regs[regno])
          {
            reload_reg_rtx[i] = gen_rtx (REG, inmode, regno);
            break;
          }
    }

  if (out)
    output_reloadnum = i;

  return i;
}

/* Record an additional place we must replace a value
   for which we have already recorded a reload.
   RELOADNUM is the value returned by push_reload
   when the reload was recorded.
   This is used in insn patterns that use match_dup.  */

static void
push_replacement (loc, reloadnum, mode)
     rtx *loc;
     int reloadnum;
     enum machine_mode mode;
{
  if (replace_reloads)
    {
      register struct replacement *r = &replacements[n_replacements++];
      r->what = reloadnum;
      r->where = loc;
      r->subreg_loc = 0;
      r->mode = mode;
    }
}
\f
/* If there is only one output reload, and it is not for an earlyclobber
   operand, try to combine it with a (logically unrelated) input reload
   to reduce the number of reload registers needed.

   This is safe if the input reload does not appear in
   the value being output-reloaded, because this implies
   it is not needed any more once the original insn completes.

   If that doesn't work, see we can use any of the registers that
   die in this insn as a reload register.  We can if it is of the right
   class and does not appear in the value being output-reloaded.  */

static void
combine_reloads ()
{
  int i;
  int output_reload = -1;
  rtx note;

  /* Find the output reload; return unless there is exactly one
     and that one is mandatory.  */

  for (i = 0; i < n_reloads; i++)
    if (reload_out[i] != 0)
      {
        if (output_reload >= 0)
          return;
        output_reload = i;
      }

  if (output_reload < 0 || reload_optional[output_reload])
    return;

  /* An input-output reload isn't combinable.  */

  if (reload_in[output_reload] != 0)
    return;

  /* If this reload is for an earlyclobber operand, we can't do anything.  */

  for (i = 0; i < n_earlyclobbers; i++)
    if (reload_out[output_reload] == reload_earlyclobbers[i])
      return;

  /* Check each input reload; can we combine it?  */

  for (i = 0; i < n_reloads; i++)
    if (reload_in[i] && ! reload_optional[i] && ! reload_nocombine[i]
        /* Life span of this reload must not extend past main insn.  */
        && reload_when_needed[i] != RELOAD_FOR_OUTPUT_RELOAD_ADDRESS
        && ! reload_needed_for_multiple[i]
        && reload_inmode[i] == reload_outmode[output_reload]
        && reload_inc[i] == 0
        && reload_reg_rtx[i] == 0
        && reload_strict_low[i] == 0
        /* Don't combine two reloads with different secondary reloads. */
        && (reload_secondary_reload[i] == reload_secondary_reload[output_reload]
            || reload_secondary_reload[i] == -1
            || reload_secondary_reload[output_reload] == -1)
        && (reg_class_subset_p (reload_reg_class[i],
                                reload_reg_class[output_reload])
            || reg_class_subset_p (reload_reg_class[output_reload],
                                   reload_reg_class[i]))
        && (MATCHES (reload_in[i], reload_out[output_reload])
            /* Args reversed because the first arg seems to be
               the one that we imagine being modified
               while the second is the one that might be affected.  */
            || (! reg_overlap_mentioned_for_reload_p (reload_out[output_reload],
                                                      reload_in[i])
                /* However, if the input is a register that appears inside
                   the output, then we also can't share.
                   Imagine (set (mem (reg 69)) (plus (reg 69) ...)).
                   If the same reload reg is used for both reg 69 and the
                   result to be stored in memory, then that result
                   will clobber the address of the memory ref.  */
                && ! (GET_CODE (reload_in[i]) == REG
                      && reg_overlap_mentioned_for_reload_p (reload_in[i],
                                                             reload_out[output_reload])))))
      {
        int j;

        /* We have found a reload to combine with!  */
        reload_out[i] = reload_out[output_reload];
        reload_outmode[i] = reload_outmode[output_reload];
        /* Mark the old output reload as inoperative.  */
        reload_out[output_reload] = 0;
        /* The combined reload is needed for the entire insn.  */
        reload_needed_for_multiple[i] = 1;
        reload_when_needed[i] = RELOAD_OTHER;
        /* If the output reload had a secondary reload, copy it. */
        if (reload_secondary_reload[output_reload] != -1)
          reload_secondary_reload[i] = reload_secondary_reload[output_reload];
        /* If required, minimize the register class. */
        if (reg_class_subset_p (reload_reg_class[output_reload],
                                reload_reg_class[i]))
          reload_reg_class[i] = reload_reg_class[output_reload];

        /* Transfer all replacements from the old reload to the combined.  */
        for (j = 0; j < n_replacements; j++)
          if (replacements[j].what == output_reload)
            replacements[j].what = i;

        return;
      }

  /* If this insn has only one operand that is modified or written (assumed
     to be the first),  it must be the one corresponding to this reload.  It
     is safe to use anything that dies in this insn for that output provided
     that it does not occur in the output (we already know it isn't an
     earlyclobber.  If this is an asm insn, give up.  */

  if (INSN_CODE (this_insn) == -1)
    return;

  for (i = 1; i < insn_n_operands[INSN_CODE (this_insn)]; i++)
    if (insn_operand_constraint[INSN_CODE (this_insn)][i][0] == '='
        || insn_operand_constraint[INSN_CODE (this_insn)][i][0] == '+')
      return;

  /* See if some hard register that dies in this insn and is not used in
     the output is the right class.  Only works if the register we pick
     up can fully hold our output reload.  */
  for (note = REG_NOTES (this_insn); note; note = XEXP (note, 1))
    if (REG_NOTE_KIND (note) == REG_DEAD
        && GET_CODE (XEXP (note, 0)) == REG
        && ! reg_overlap_mentioned_for_reload_p (XEXP (note, 0),
                                                 reload_out[output_reload])
        && REGNO (XEXP (note, 0)) < FIRST_PSEUDO_REGISTER
        && HARD_REGNO_MODE_OK (REGNO (XEXP (note, 0)), reload_outmode[output_reload])
        && TEST_HARD_REG_BIT (reg_class_contents[(int) reload_reg_class[output_reload]],
                              REGNO (XEXP (note, 0)))
        && (HARD_REGNO_NREGS (REGNO (XEXP (note, 0)), reload_outmode[output_reload])
            <= HARD_REGNO_NREGS (REGNO (XEXP (note, 0)), GET_MODE (XEXP (note, 0))))
        && ! fixed_regs[REGNO (XEXP (note, 0))])
      {
        reload_reg_rtx[output_reload] = gen_rtx (REG,
                                                 reload_outmode[output_reload],
                                                 REGNO (XEXP (note, 0)));
        return;
      }
}
\f
/* Try to find a reload register for an in-out reload (expressions IN and OUT).
   See if one of IN and OUT is a register that may be used;
   this is desirable since a spill-register won't be needed.
   If so, return the register rtx that proves acceptable.

   INLOC and OUTLOC are locations where IN and OUT appear in the insn.
   CLASS is the register class required for the reload.

   If FOR_REAL is >= 0, it is the number of the reload,
   and in some cases when it can be discovered that OUT doesn't need
   to be computed, clear out reload_out[FOR_REAL].

   If FOR_REAL is -1, this should not be done, because this call
   is just to see if a register can be found, not to find and install it.  */

static rtx
find_dummy_reload (real_in, real_out, inloc, outloc, class, for_real)
     rtx real_in, real_out;
     rtx *inloc, *outloc;
     enum reg_class class;
     int for_real;
{
  rtx in = real_in;
  rtx out = real_out;
  int in_offset = 0;
  int out_offset = 0;
  rtx value = 0;

  /* If operands exceed a word, we can't use either of them
     unless they have the same size.  */
  if (GET_MODE_SIZE (GET_MODE (real_out)) != GET_MODE_SIZE (GET_MODE (real_in))
      && (GET_MODE_SIZE (GET_MODE (real_out)) > UNITS_PER_WORD
          || GET_MODE_SIZE (GET_MODE (real_in)) > UNITS_PER_WORD))
    return 0;

  /* Find the inside of any subregs.  */
  while (GET_CODE (out) == SUBREG)
    {
      out_offset = SUBREG_WORD (out);
      out = SUBREG_REG (out);
    }
  while (GET_CODE (in) == SUBREG)
    {
      in_offset = SUBREG_WORD (in);
      in = SUBREG_REG (in);
    }

  /* Narrow down the reg class, the same way push_reload will;
     otherwise we might find a dummy now, but push_reload won't.  */
  class = PREFERRED_RELOAD_CLASS (in, class);

  /* See if OUT will do.  */
  if (GET_CODE (out) == REG
      && REGNO (out) < FIRST_PSEUDO_REGISTER)
    {
      register int regno = REGNO (out) + out_offset;
      int nwords = HARD_REGNO_NREGS (regno, GET_MODE (real_out));
      rtx saved_rtx;

      /* When we consider whether the insn uses OUT,
         ignore references within IN.  They don't prevent us
         from copying IN into OUT, because those refs would
         move into the insn that reloads IN.

         However, we only ignore IN in its role as this reload.
         If the insn uses IN elsewhere and it contains OUT,
         that counts.  We can't be sure it's the "same" operand
         so it might not go through this reload.  */
      saved_rtx = *inloc;
      *inloc = const0_rtx;

      if (regno < FIRST_PSEUDO_REGISTER
          /* A fixed reg that can overlap other regs better not be used
             for reloading in any way.  */
#ifdef OVERLAPPING_REGNO_P
          && ! (fixed_regs[regno] && OVERLAPPING_REGNO_P (regno))
#endif
          && ! refers_to_regno_for_reload_p (regno, regno + nwords,
                                             PATTERN (this_insn), outloc))
        {
          int i;
          for (i = 0; i < nwords; i++)
            if (! TEST_HARD_REG_BIT (reg_class_contents[(int) class],
                                     regno + i))
              break;

          if (i == nwords)
            {
              if (GET_CODE (real_out) == REG)
                value = real_out;
              else
                value = gen_rtx (REG, GET_MODE (real_out), regno);
            }
        }

      *inloc = saved_rtx;
    }

  /* Consider using IN if OUT was not acceptable
     or if OUT dies in this insn (like the quotient in a divmod insn).
     We can't use IN unless it is dies in this insn,
     which means we must know accurately which hard regs are live.
     Also, the result can't go in IN if IN is used within OUT.  */
  if (hard_regs_live_known
      && GET_CODE (in) == REG
      && REGNO (in) < FIRST_PSEUDO_REGISTER
      && (value == 0
          || find_reg_note (this_insn, REG_UNUSED, real_out))
      && find_reg_note (this_insn, REG_DEAD, real_in)
      && !fixed_regs[REGNO (in)]
      && HARD_REGNO_MODE_OK (REGNO (in), GET_MODE (out)))
    {
      register int regno = REGNO (in) + in_offset;
      int nwords = HARD_REGNO_NREGS (regno, GET_MODE (real_in));

      if (! refers_to_regno_for_reload_p (regno, regno + nwords, out, NULL_PTR)
          && ! hard_reg_set_here_p (regno, regno + nwords,
                                    PATTERN (this_insn)))
        {
          int i;
          for (i = 0; i < nwords; i++)
            if (! TEST_HARD_REG_BIT (reg_class_contents[(int) class],
                                     regno + i))
              break;

          if (i == nwords)
            {
              /* If we were going to use OUT as the reload reg
                 and changed our mind, it means OUT is a dummy that
                 dies here.  So don't bother copying value to it.  */
              if (for_real >= 0 && value == real_out)
                reload_out[for_real] = 0;
              if (GET_CODE (real_in) == REG)
                value = real_in;
              else
                value = gen_rtx (REG, GET_MODE (real_in), regno);
            }
        }
    }

  return value;
}
\f
/* This page contains subroutines used mainly for determining
   whether the IN or an OUT of a reload can serve as the
   reload register.  */

/* Return 1 if expression X alters a hard reg in the range
   from BEG_REGNO (inclusive) to END_REGNO (exclusive),
   either explicitly or in the guise of a pseudo-reg allocated to REGNO.
   X should be the body of an instruction.  */

static int
hard_reg_set_here_p (beg_regno, end_regno, x)
     register int beg_regno, end_regno;
     rtx x;
{
  if (GET_CODE (x) == SET || GET_CODE (x) == CLOBBER)
    {
      register rtx op0 = SET_DEST (x);
      while (GET_CODE (op0) == SUBREG)
        op0 = SUBREG_REG (op0);
      if (GET_CODE (op0) == REG)
        {
          register int r = REGNO (op0);
          /* See if this reg overlaps range under consideration.  */
          if (r < end_regno
              && r + HARD_REGNO_NREGS (r, GET_MODE (op0)) > beg_regno)
            return 1;
        }
    }
  else if (GET_CODE (x) == PARALLEL)
    {
      register int i = XVECLEN (x, 0) - 1;
      for (; i >= 0; i--)
        if (hard_reg_set_here_p (beg_regno, end_regno, XVECEXP (x, 0, i)))
          return 1;
    }

  return 0;
}

/* Return 1 if ADDR is a valid memory address for mode MODE,
   and check that each pseudo reg has the proper kind of
   hard reg.  */

int
strict_memory_address_p (mode, addr)
     enum machine_mode mode;
     register rtx addr;
{
  GO_IF_LEGITIMATE_ADDRESS (mode, addr, win);
  return 0;

 win:
  return 1;
}

\f
/* Like rtx_equal_p except that it allows a REG and a SUBREG to match
   if they are the same hard reg, and has special hacks for
   autoincrement and autodecrement.
   This is specifically intended for find_reloads to use
   in determining whether two operands match.
   X is the operand whose number is the lower of the two.

   The value is 2 if Y contains a pre-increment that matches
   a non-incrementing address in X.  */

/* ??? To be completely correct, we should arrange to pass
   for X the output operand and for Y the input operand.
   For now, we assume that the output operand has the lower number
   because that is natural in (SET output (... input ...)).  */

int
operands_match_p (x, y)
     register rtx x, y;
{
  register int i;
  register RTX_CODE code = GET_CODE (x);
  register char *fmt;
  int success_2;
      
  if (x == y)
    return 1;
  if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
      && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
                                  && GET_CODE (SUBREG_REG (y)) == REG)))
    {
      register int j;

      if (code == SUBREG)
        {
          i = REGNO (SUBREG_REG (x));
          if (i >= FIRST_PSEUDO_REGISTER)
            goto slow;
          i += SUBREG_WORD (x);
        }
      else
        i = REGNO (x);

      if (GET_CODE (y) == SUBREG)
        {
          j = REGNO (SUBREG_REG (y));
          if (j >= FIRST_PSEUDO_REGISTER)
            goto slow;
          j += SUBREG_WORD (y);
        }
      else
        j = REGNO (y);

      return i == j;
    }
  /* If two operands must match, because they are really a single
     operand of an assembler insn, then two postincrements are invalid
     because the assembler insn would increment only once.
     On the other hand, an postincrement matches ordinary indexing
     if the postincrement is the output operand.  */
  if (code == POST_DEC || code == POST_INC)
    return operands_match_p (XEXP (x, 0), y);
  /* Two preincrements are invalid
     because the assembler insn would increment only once.
     On the other hand, an preincrement matches ordinary indexing
     if the preincrement is the input operand.
     In this case, return 2, since some callers need to do special
     things when this happens.  */
  if (GET_CODE (y) == PRE_DEC || GET_CODE (y) == PRE_INC)
    return operands_match_p (x, XEXP (y, 0)) ? 2 : 0;

 slow:

  /* Now we have disposed of all the cases 
     in which different rtx codes can match.  */
  if (code != GET_CODE (y))
    return 0;
  if (code == LABEL_REF)
    return XEXP (x, 0) == XEXP (y, 0);
  if (code == SYMBOL_REF)
    return XSTR (x, 0) == XSTR (y, 0);

  /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.  */

  if (GET_MODE (x) != GET_MODE (y))
    return 0;

  /* Compare the elements.  If any pair of corresponding elements
     fail to match, return 0 for the whole things.  */

  success_2 = 0;
  fmt = GET_RTX_FORMAT (code);
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      int val;
      switch (fmt[i])
        {
        case 'w':
          if (XWINT (x, i) != XWINT (y, i))
            return 0;
          break;

        case 'i':
          if (XINT (x, i) != XINT (y, i))
            return 0;
          break;

        case 'e':
          val = operands_match_p (XEXP (x, i), XEXP (y, i));
          if (val == 0)
            return 0;
          /* If any subexpression returns 2,
             we should return 2 if we are successful.  */
          if (val == 2)
            success_2 = 1;
          break;

        case '0':
          break;

          /* It is believed that rtx's at this level will never
             contain anything but integers and other rtx's,
             except for within LABEL_REFs and SYMBOL_REFs.  */
        default:
          abort ();
        }
    }
  return 1 + success_2;
}
\f
/* Return the number of times character C occurs in string S.  */

int
n_occurrences (c, s)
     char c;
     char *s;
{
  int n = 0;
  while (*s)
    n += (*s++ == c);
  return n;
}
\f
struct decomposition
{
  int reg_flag;
  int safe;
  rtx base;
  HOST_WIDE_INT start;
  HOST_WIDE_INT end;
};

/* Describe the range of registers or memory referenced by X.
   If X is a register, set REG_FLAG and put the first register 
   number into START and the last plus one into END.
   If X is a memory reference, put a base address into BASE 
   and a range of integer offsets into START and END.
   If X is pushing on the stack, we can assume it causes no trouble, 
   so we set the SAFE field.  */

static struct decomposition
decompose (x)
     rtx x;
{
  struct decomposition val;
  int all_const = 0;

  val.reg_flag = 0;
  val.safe = 0;
  if (GET_CODE (x) == MEM)
    {
      rtx base, offset = 0;
      rtx addr = XEXP (x, 0);

      if (GET_CODE (addr) == PRE_DEC || GET_CODE (addr) == PRE_INC
          || GET_CODE (addr) == POST_DEC || GET_CODE (addr) == POST_INC)
        {
          val.base = XEXP (addr, 0);
          val.start = - GET_MODE_SIZE (GET_MODE (x));
          val.end = GET_MODE_SIZE (GET_MODE (x));
          val.safe = REGNO (val.base) == STACK_POINTER_REGNUM;
          return val;
        }

      if (GET_CODE (addr) == CONST)
        {
          addr = XEXP (addr, 0);
          all_const = 1;
        }
      if (GET_CODE (addr) == PLUS)
        {
          if (CONSTANT_P (XEXP (addr, 0)))
            {
              base = XEXP (addr, 1);
              offset = XEXP (addr, 0);
            }
          else if (CONSTANT_P (XEXP (addr, 1)))
            {
              base = XEXP (addr, 0);
              offset = XEXP (addr, 1);
            }
        }

      if (offset == 0)
        {
          base = addr;
          offset = const0_rtx;
        } 
      if (GET_CODE (offset) == CONST)
        offset = XEXP (offset, 0);
      if (GET_CODE (offset) == PLUS)
        {
          if (GET_CODE (XEXP (offset, 0)) == CONST_INT)
            {
              base = gen_rtx (PLUS, GET_MODE (base), base, XEXP (offset, 1));
              offset = XEXP (offset, 0);
            }
          else if (GET_CODE (XEXP (offset, 1)) == CONST_INT)
            {
              base = gen_rtx (PLUS, GET_MODE (base), base, XEXP (offset, 0));
              offset = XEXP (offset, 1);
            }
          else
            {
              base = gen_rtx (PLUS, GET_MODE (base), base, offset);
              offset = const0_rtx;
            }
        }
      else if (GET_CODE (offset) != CONST_INT)
        {
          base = gen_rtx (PLUS, GET_MODE (base), base, offset);
          offset = const0_rtx;
        }

      if (all_const && GET_CODE (base) == PLUS)
        base = gen_rtx (CONST, GET_MODE (base), base);

      if (GET_CODE (offset) != CONST_INT)
        abort ();

      val.start = INTVAL (offset);
      val.end = val.start + GET_MODE_SIZE (GET_MODE (x));
      val.base = base;
      return val;
    }
  else if (GET_CODE (x) == REG)
    {
      val.reg_flag = 1;
      val.start = true_regnum (x); 
      if (val.start < 0)
        {
          /* A pseudo with no hard reg.  */
          val.start = REGNO (x);
          val.end = val.start + 1;
        }
      else
        /* A hard reg.  */
        val.end = val.start + HARD_REGNO_NREGS (val.start, GET_MODE (x));
    }
  else if (GET_CODE (x) == SUBREG)
    {
      if (GET_CODE (SUBREG_REG (x)) != REG)
        /* This could be more precise, but it's good enough.  */
        return decompose (SUBREG_REG (x));
      val.reg_flag = 1;
      val.start = true_regnum (x); 
      if (val.start < 0)
        return decompose (SUBREG_REG (x));
      else
        /* A hard reg.  */
        val.end = val.start + HARD_REGNO_NREGS (val.start, GET_MODE (x));
    }
  else if (CONSTANT_P (x)
           /* This hasn't been assigned yet, so it can't conflict yet.  */
           || GET_CODE (x) == SCRATCH)
    val.safe = 1;
  else
    abort ();
  return val;
}

/* Return 1 if altering Y will not modify the value of X.
   Y is also described by YDATA, which should be decompose (Y).  */

static int
immune_p (x, y, ydata)
     rtx x, y;
     struct decomposition ydata;
{
  struct decomposition xdata;

  if (ydata.reg_flag)
    return !refers_to_regno_for_reload_p (ydata.start, ydata.end, x, NULL_PTR);
  if (ydata.safe)
    return 1;

  if (GET_CODE (y) != MEM)
    abort ();
  /* If Y is memory and X is not, Y can't affect X.  */
  if (GET_CODE (x) != MEM)
    return 1;

  xdata =  decompose (x);

  if (! rtx_equal_p (xdata.base, ydata.base))
    {
      /* If bases are distinct symbolic constants, there is no overlap.  */
      if (CONSTANT_P (xdata.base) && CONSTANT_P (ydata.base))
        return 1;
      /* Constants and stack slots never overlap.  */
      if (CONSTANT_P (xdata.base)
          && (ydata.base == frame_pointer_rtx
              || ydata.base == stack_pointer_rtx))
        return 1;
      if (CONSTANT_P (ydata.base)
          && (xdata.base == frame_pointer_rtx
              || xdata.base == stack_pointer_rtx))
        return 1;
      /* If either base is variable, we don't know anything.  */
      return 0;
    }


  return (xdata.start >= ydata.end || ydata.start >= xdata.end);
}

/* Similar, but calls decompose.  */

int
safe_from_earlyclobber (op, clobber)
     rtx op, clobber;
{
  struct decomposition early_data;

  early_data = decompose (clobber);
  return immune_p (op, clobber, early_data);
}
\f
/* Main entry point of this file: search the body of INSN
   for values that need reloading and record them with push_reload.
   REPLACE nonzero means record also where the values occur
   so that subst_reloads can be used.

   IND_LEVELS says how many levels of indirection are supported by this
   machine; a value of zero means that a memory reference is not a valid
   memory address.

   LIVE_KNOWN says we have valid information about which hard
   regs are live at each point in the program; this is true when
   we are called from global_alloc but false when stupid register
   allocation has been done.

   RELOAD_REG_P if nonzero is a vector indexed by hard reg number
   which is nonnegative if the reg has been commandeered for reloading into.
   It is copied into STATIC_RELOAD_REG_P and referenced from there
   by various subroutines.  */

void
find_reloads (insn, replace, ind_levels, live_known, reload_reg_p)
     rtx insn;
     int replace, ind_levels;
     int live_known;
     short *reload_reg_p;
{
  rtx non_reloaded_operands[MAX_RECOG_OPERANDS];
  int n_non_reloaded_operands = 0;
#ifdef REGISTER_CONSTRAINTS

  enum reload_modified { RELOAD_NOTHING, RELOAD_READ, RELOAD_READ_WRITE, RELOAD_WRITE };

  register int insn_code_number;
  register int i;
  int noperands;
  /* These are the constraints for the insn.  We don't change them.  */
  char *constraints1[MAX_RECOG_OPERANDS];
  /* These start out as the constraints for the insn
     and they are chewed up as we consider alternatives.  */
  char *constraints[MAX_RECOG_OPERANDS];
  /* These are the preferred classes for an operand, or NO_REGS if it isn't
     a register.  */
  enum reg_class preferred_class[MAX_RECOG_OPERANDS];
  char pref_or_nothing[MAX_RECOG_OPERANDS];
  /* Nonzero for a MEM operand whose entire address needs a reload.  */
  int address_reloaded[MAX_RECOG_OPERANDS];
  int no_input_reloads = 0, no_output_reloads = 0;
  int n_alternatives;
  int this_alternative[MAX_RECOG_OPERANDS];
  char this_alternative_win[MAX_RECOG_OPERANDS];
  char this_alternative_offmemok[MAX_RECOG_OPERANDS];
  char this_alternative_earlyclobber[MAX_RECOG_OPERANDS];
  int this_alternative_matches[MAX_RECOG_OPERANDS];
  int swapped;
  int goal_alternative[MAX_RECOG_OPERANDS];
  int this_alternative_number;
  int goal_alternative_number;
  int operand_reloadnum[MAX_RECOG_OPERANDS];
  int goal_alternative_matches[MAX_RECOG_OPERANDS];
  int goal_alternative_matched[MAX_RECOG_OPERANDS];
  char goal_alternative_win[MAX_RECOG_OPERANDS];
  char goal_alternative_offmemok[MAX_RECOG_OPERANDS];
  char goal_alternative_earlyclobber[MAX_RECOG_OPERANDS];
  int goal_alternative_swapped;
  enum reload_modified modified[MAX_RECOG_OPERANDS];
  int best;
  int commutative;
  char operands_match[MAX_RECOG_OPERANDS][MAX_RECOG_OPERANDS];
  rtx substed_operand[MAX_RECOG_OPERANDS];
  rtx body = PATTERN (insn);
  rtx set = single_set (insn);
  int goal_earlyclobber, this_earlyclobber;
  enum machine_mode operand_mode[MAX_RECOG_OPERANDS];

  this_insn = insn;
  this_insn_is_asm = 0;         /* Tentative.  */
  n_reloads = 0;
  n_replacements = 0;
  n_memlocs = 0;
  n_earlyclobbers = 0;
  replace_reloads = replace;
  hard_regs_live_known = live_known;
  static_reload_reg_p = reload_reg_p;

  /* JUMP_INSNs and CALL_INSNs are not allowed to have any output reloads;
     neither are insns that SET cc0.  Insns that use CC0 are not allowed
     to have any input reloads.  */
  if (GET_CODE (insn) == JUMP_INSN || GET_CODE (insn) == CALL_INSN)
    no_output_reloads = 1;

#ifdef HAVE_cc0
  if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
    no_input_reloads = 1;
  if (reg_set_p (cc0_rtx, PATTERN (insn)))
    no_output_reloads = 1;
#endif
     
#ifdef SECONDARY_MEMORY_NEEDED
  /* The eliminated forms of any secondary memory locations are per-insn, so
     clear them out here.  */

  bzero (secondary_memlocs_elim, sizeof secondary_memlocs_elim);
#endif

  /* Find what kind of insn this is.  NOPERANDS gets number of operands.
     Make OPERANDS point to a vector of operand values.
     Make OPERAND_LOCS point to a vector of pointers to
     where the operands were found.
     Fill CONSTRAINTS and CONSTRAINTS1 with pointers to the
     constraint-strings for this insn.
     Return if the insn needs no reload processing.  */

  switch (GET_CODE (body))
    {
    case USE:
    case CLOBBER:
    case ASM_INPUT:
    case ADDR_VEC:
    case ADDR_DIFF_VEC:
      return;

    case SET:
      /* Dispose quickly of (set (reg..) (reg..)) if both have hard regs and it
         is cheap to move between them.  If it is not, there may not be an insn
         to do the copy, so we may need a reload.  */
      if (GET_CODE (SET_DEST (body)) == REG
          && REGNO (SET_DEST (body)) < FIRST_PSEUDO_REGISTER
          && GET_CODE (SET_SRC (body)) == REG
          && REGNO (SET_SRC (body)) < FIRST_PSEUDO_REGISTER
          && REGISTER_MOVE_COST (REGNO_REG_CLASS (REGNO (SET_SRC (body))),
                                 REGNO_REG_CLASS (REGNO (SET_DEST (body)))) == 2)
        return;
    case PARALLEL:
    case ASM_OPERANDS:
      noperands = asm_noperands (body);
      if (noperands >= 0)
        {
          /* This insn is an `asm' with operands.  */

          insn_code_number = -1;
          this_insn_is_asm = 1;

          /* expand_asm_operands makes sure there aren't too many operands.  */
          if (noperands > MAX_RECOG_OPERANDS)
            abort ();

          /* Now get the operand values and constraints out of the insn.  */

          decode_asm_operands (body, recog_operand, recog_operand_loc,
                               constraints, operand_mode);
          if (noperands > 0)
            {
              bcopy (constraints, constraints1, noperands * sizeof (char *));
              n_alternatives = n_occurrences (',', constraints[0]) + 1;
              for (i = 1; i < noperands; i++)
                if (n_alternatives != n_occurrences (',', constraints[i]) + 1)
                  {
                    error_for_asm (insn, "operand constraints differ in number of alternatives");
                    /* Avoid further trouble with this insn.  */
                    PATTERN (insn) = gen_rtx (USE, VOIDmode, const0_rtx);
                    n_reloads = 0;
                    return;
                  }
            }
          break;
        }

    default:
      /* Ordinary insn: recognize it, get the operands via insn_extract
         and get the constraints.  */

      insn_code_number = recog_memoized (insn);
      if (insn_code_number < 0)
        fatal_insn_not_found (insn);

      noperands = insn_n_operands[insn_code_number];
      n_alternatives = insn_n_alternatives[insn_code_number];
      /* Just return "no reloads" if insn has no operands with constraints.  */
      if (n_alternatives == 0)
        return;
      insn_extract (insn);
      for (i = 0; i < noperands; i++)
        {
          constraints[i] = constraints1[i]
            = insn_operand_constraint[insn_code_number][i];
          operand_mode[i] = insn_operand_mode[insn_code_number][i];
        }
    }

  if (noperands == 0)
    return;

  commutative = -1;

  /* If we will need to know, later, whether some pair of operands
     are the same, we must compare them now and save the result.
     Reloading the base and index registers will clobber them
     and afterward they will fail to match.  */

  for (i = 0; i < noperands; i++)
    {
      register char *p;
      register int c;

      substed_operand[i] = recog_operand[i];
      p = constraints[i];

      /* Scan this operand's constraint to see if it should match another.  */

      while (c = *p++)
        if (c == '%')
          {
            /* The last operand should not be marked commutative.  */
            if (i == noperands - 1)
              {
                if (this_insn_is_asm)
                  warning_for_asm (this_insn,
                                   "`%%' constraint used with last operand");
                else
                  abort ();
              }
            else
              commutative = i;
          }
        else if (c >= '0' && c <= '9')
          {
            c -= '0';
            operands_match[c][i]
              = operands_match_p (recog_operand[c], recog_operand[i]);

            /* An operand may not match itself.  */
            if (c == i)
              {
                if (this_insn_is_asm)
                  warning_for_asm (this_insn,
                                   "operand %d has constraint %d", i, c);
                else
                  abort ();
              }

            /* If C can be commuted with C+1, and C might need to match I,
               then C+1 might also need to match I.  */
            if (commutative >= 0)
              {
                if (c == commutative || c == commutative + 1)
                  {
                    int other = c + (c == commutative ? 1 : -1);
                    operands_match[other][i]
                      = operands_match_p (recog_operand[other], recog_operand[i]);
                  }
                if (i == commutative || i == commutative + 1)
                  {
                    int other = i + (i == commutative ? 1 : -1);
                    operands_match[c][other]
                      = operands_match_p (recog_operand[c], recog_operand[other]);
                  }
                /* Note that C is supposed to be less than I.
                   No need to consider altering both C and I
                   because in that case we would alter one into the other.  */
              }
          }
    }

  /* Examine each operand that is a memory reference or memory address
     and reload parts of the addresses into index registers.
     While we are at it, initialize the array `modified'.
     Also here any references to pseudo regs that didn't get hard regs
     but are equivalent to constants get replaced in the insn itself
     with those constants.  Nobody will ever see them again. 

     Finally, set up the preferred classes of each operand.  */

  for (i = 0; i < noperands; i++)
    {
      register RTX_CODE code = GET_CODE (recog_operand[i]);
      modified[i] = RELOAD_READ;
      address_reloaded[i] = 0;

      if (constraints[i][0] == 'p')
        {
          find_reloads_address (VOIDmode, NULL_PTR,
                                recog_operand[i], recog_operand_loc[i],
                                recog_operand[i], ind_levels);
          substed_operand[i] = recog_operand[i] = *recog_operand_loc[i];
        }
      else if (code == MEM)
        {
          if (find_reloads_address (GET_MODE (recog_operand[i]),
                                    recog_operand_loc[i],
                                    XEXP (recog_operand[i], 0),
                                    &XEXP (recog_operand[i], 0),
                                    recog_operand[i], ind_levels))
            address_reloaded[i] = 1;
          substed_operand[i] = recog_operand[i] = *recog_operand_loc[i];
        }
      else if (code == SUBREG)
        substed_operand[i] = recog_operand[i] = *recog_operand_loc[i]
          = find_reloads_toplev (recog_operand[i], ind_levels,
                                 set != 0
                                 && &SET_DEST (set) == recog_operand_loc[i]);
      else if (code == REG)
        {
          /* This is equivalent to calling find_reloads_toplev.
             The code is duplicated for speed.
             When we find a pseudo always equivalent to a constant,
             we replace it by the constant.  We must be sure, however,
             that we don't try to replace it in the insn in which it
             is being set.   */
          register int regno = REGNO (recog_operand[i]);
          if (reg_equiv_constant[regno] != 0
              && (set == 0 || &SET_DEST (set) != recog_operand_loc[i]))
            substed_operand[i] = recog_operand[i]
              = reg_equiv_constant[regno];
#if 0 /* This might screw code in reload1.c to delete prior output-reload
         that feeds this insn.  */
          if (reg_equiv_mem[regno] != 0)
            substed_operand[i] = recog_operand[i]
              = reg_equiv_mem[regno];
#endif
          if (reg_equiv_address[regno] != 0)
            {
              /* If reg_equiv_address is not a constant address, copy it,
                 since it may be shared.  */
              rtx address = reg_equiv_address[regno];

              if (rtx_varies_p (address))
                address = copy_rtx (address);

              /* If this is an output operand, we must output a CLOBBER
                 after INSN so find_equiv_reg knows REGNO is being written. */
              if (constraints[i][0] == '='
                  || constraints[i][0] == '+')
                emit_insn_after (gen_rtx (CLOBBER, VOIDmode, recog_operand[i]),
                                 insn);

              *recog_operand_loc[i] = recog_operand[i]
                = gen_rtx (MEM, GET_MODE (recog_operand[i]), address);
              RTX_UNCHANGING_P (recog_operand[i])
                = RTX_UNCHANGING_P (regno_reg_rtx[regno]);
              find_reloads_address (GET_MODE (recog_operand[i]),
                                    recog_operand_loc[i],
                                    XEXP (recog_operand[i], 0),
                                    &XEXP (recog_operand[i], 0),
                                    recog_operand[i], ind_levels);
              substed_operand[i] = recog_operand[i] = *recog_operand_loc[i];
            }
        }
      /* If the operand is still a register (we didn't replace it with an
         equivalent), get the preferred class to reload it into.  */
      code = GET_CODE (recog_operand[i]);
      preferred_class[i]
        = ((code == REG && REGNO (recog_operand[i]) >= FIRST_PSEUDO_REGISTER)
           ? reg_preferred_class (REGNO (recog_operand[i])) : NO_REGS);
      pref_or_nothing[i]
        = (code == REG && REGNO (recog_operand[i]) >= FIRST_PSEUDO_REGISTER
           && reg_alternate_class (REGNO (recog_operand[i])) == NO_REGS);
    }

  /* If this is simply a copy from operand 1 to operand 0, merge the
     preferred classes for the operands.  */
  if (set != 0 && noperands >= 2 && recog_operand[0] == SET_DEST (set)
      && recog_operand[1] == SET_SRC (set))
    {
      preferred_class[0] = preferred_class[1]
        = reg_class_subunion[(int) preferred_class[0]][(int) preferred_class[1]];
      pref_or_nothing[0] |= pref_or_nothing[1];
      pref_or_nothing[1] |= pref_or_nothing[0];
    }

  /* Now see what we need for pseudo-regs that didn't get hard regs
     or got the wrong kind of hard reg.  For this, we must consider
     all the operands together against the register constraints.  */

  best = MAX_RECOG_OPERANDS + 300;

  swapped = 0;
  goal_alternative_swapped = 0;
 try_swapped:

  /* The constraints are made of several alternatives.
     Each operand's constraint looks like foo,bar,... with commas
     separating the alternatives.  The first alternatives for all
     operands go together, the second alternatives go together, etc.

     First loop over alternatives.  */

  for (this_alternative_number = 0;
       this_alternative_number < n_alternatives;
       this_alternative_number++)
    {
      /* Loop over operands for one constraint alternative.  */
      /* LOSERS counts those that don't fit this alternative
         and would require loading.  */
      int losers = 0;
      /* BAD is set to 1 if it some operand can't fit this alternative
         even after reloading.  */
      int bad = 0;
      /* REJECT is a count of how undesirable this alternative says it is
         if any reloading is required.  If the alternative matches exactly
         then REJECT is ignored, but otherwise it gets this much
         counted against it in addition to the reloading needed.  Each 
         ? counts three times here since we want the disparaging caused by
         a bad register class to only count 1/3 as much.  */
      int reject = 0;

      this_earlyclobber = 0;

      for (i = 0; i < noperands; i++)
        {
          register char *p = constraints[i];
          register int win = 0;
          /* 0 => this operand can be reloaded somehow for this alternative */
          int badop = 1;
          /* 0 => this operand can be reloaded if the alternative allows regs.  */
          int winreg = 0;
          int c;
          register rtx operand = recog_operand[i];
          int offset = 0;
          /* Nonzero means this is a MEM that must be reloaded into a reg
             regardless of what the constraint says.  */
          int force_reload = 0;
          int offmemok = 0;
          int earlyclobber = 0;

          /* If the operand is a SUBREG, extract
             the REG or MEM (or maybe even a constant) within.
             (Constants can occur as a result of reg_equiv_constant.)  */

          while (GET_CODE (operand) == SUBREG)
            {
              offset += SUBREG_WORD (operand);
              operand = SUBREG_REG (operand);
              /* Force reload if this is not a register or if there may may
                 be a problem accessing the register in the outer mode.  */
              if (GET_CODE (operand) != REG
#if defined(BYTE_LOADS_ZERO_EXTEND) || defined(BYTE_LOADS_SIGN_EXTEND)
                  /* ??? The comment below clearly does not match the code.
                     What the code below actually does is set force_reload
                     for a paradoxical subreg of a pseudo.  rms and kenner
                     can't see the point of doing this.  */
                  /* Nonparadoxical subreg of a pseudoreg.
                     Don't to load the full width if on this machine
                     we expected the fetch to extend.  */
                  || ((GET_MODE_SIZE (operand_mode[i])
                       > GET_MODE_SIZE (GET_MODE (operand)))
                      && REGNO (operand) >= FIRST_PSEUDO_REGISTER)
#endif
                  /* Subreg of a hard reg which can't handle the subreg's mode
                     or which would handle that mode in the wrong number of
                     registers for subregging to work.  */
                  || (REGNO (operand) < FIRST_PSEUDO_REGISTER
                      && (! HARD_REGNO_MODE_OK (REGNO (operand),
                                                operand_mode[i])
                          || (GET_MODE_SIZE (operand_mode[i]) <= UNITS_PER_WORD
                              && (GET_MODE_SIZE (GET_MODE (operand))
                                  > UNITS_PER_WORD)
                              && ((GET_MODE_SIZE (GET_MODE (operand))
                                   / UNITS_PER_WORD)
                                  != HARD_REGNO_NREGS (REGNO (operand),
                                                       GET_MODE (operand)))))))
                force_reload = 1;
            }

          this_alternative[i] = (int) NO_REGS;
          this_alternative_win[i] = 0;
          this_alternative_offmemok[i] = 0;
          this_alternative_earlyclobber[i] = 0;
          this_alternative_matches[i] = -1;

          /* An empty constraint or empty alternative
             allows anything which matched the pattern.  */
          if (*p == 0 || *p == ',')
            win = 1, badop = 0;

          /* Scan this alternative's specs for this operand;
             set WIN if the operand fits any letter in this alternative.
             Otherwise, clear BADOP if this operand could
             fit some letter after reloads,
             or set WINREG if this operand could fit after reloads
             provided the constraint allows some registers.  */

          while (*p && (c = *p++) != ',')
            switch (c)
              {
              case '=':
                modified[i] = RELOAD_WRITE;
                break;

              case '+':
                modified[i] = RELOAD_READ_WRITE;
                break;

              case '*':
                break;

              case '%':
                /* The last operand should not be marked commutative.  */
                if (i != noperands - 1)
                  commutative = i;
                break;

              case '?':
                reject += 3;
                break;

              case '!':
                reject = 300;
                break;

              case '#':
                /* Ignore rest of this alternative as far as
                   reloading is concerned.  */
                while (*p && *p != ',') p++;
                break;

              case '0':
              case '1':
              case '2':
              case '3':
              case '4':
                c -= '0';
                this_alternative_matches[i] = c;
                /* We are supposed to match a previous operand.
                   If we do, we win if that one did.
                   If we do not, count both of the operands as losers.
                   (This is too conservative, since most of the time
                   only a single reload insn will be needed to make
                   the two operands win.  As a result, this alternative
                   may be rejected when it is actually desirable.)  */
                if ((swapped && (c != commutative || i != commutative + 1))
                    /* If we are matching as if two operands were swapped,
                       also pretend that operands_match had been computed
                       with swapped.
                       But if I is the second of those and C is the first,
                       don't exchange them, because operands_match is valid
                       only on one side of its diagonal.  */
                    ? (operands_match
                        [(c == commutative || c == commutative + 1)
                         ? 2*commutative + 1 - c : c]
                        [(i == commutative || i == commutative + 1)
                         ? 2*commutative + 1 - i : i])
                    : operands_match[c][i])
                  win = this_alternative_win[c];
                else
                  {
                    /* Operands don't match.  */
                    rtx value;
                    /* Retroactively mark the operand we had to match
                       as a loser, if it wasn't already.  */
                    if (this_alternative_win[c])
                      losers++;
                    this_alternative_win[c] = 0;
                    if (this_alternative[c] == (int) NO_REGS)
                      bad = 1;
                    /* But count the pair only once in the total badness of
                       this alternative, if the pair can be a dummy reload.  */
                    value
                      = find_dummy_reload (recog_operand[i], recog_operand[c],
                                           recog_operand_loc[i], recog_operand_loc[c],
                                           this_alternative[c], -1);

                    if (value != 0)
                      losers--;
                  }
                /* This can be fixed with reloads if the operand
                   we are supposed to match can be fixed with reloads.  */
                badop = 0;
                this_alternative[i] = this_alternative[c];
                break;

              case 'p':
                /* All necessary reloads for an address_operand
                   were handled in find_reloads_address.  */
                this_alternative[i] = (int) ALL_REGS;
                win = 1;
                break;

              case 'm':
                if (force_reload)
                  break;
                if (GET_CODE (operand) == MEM
                    || (GET_CODE (operand) == REG
                        && REGNO (operand) >= FIRST_PSEUDO_REGISTER
                        && reg_renumber[REGNO (operand)] < 0))
                  win = 1;
                if (CONSTANT_P (operand))
                  badop = 0;
                break;

              case '<':
                if (GET_CODE (operand) == MEM
                    && ! address_reloaded[i]
                    && (GET_CODE (XEXP (operand, 0)) == PRE_DEC
                        || GET_CODE (XEXP (operand, 0)) == POST_DEC))
                  win = 1;
                break;

              case '>':
                if (GET_CODE (operand) == MEM
                    && ! address_reloaded[i]
                    && (GET_CODE (XEXP (operand, 0)) == PRE_INC
                        || GET_CODE (XEXP (operand, 0)) == POST_INC))
                  win = 1;
                break;

                /* Memory operand whose address is not offsettable.  */
              case 'V':
                if (force_reload)
                  break;
                if (GET_CODE (operand) == MEM
                    && ! (ind_levels ? offsettable_memref_p (operand)
                          : offsettable_nonstrict_memref_p (operand))
                    /* Certain mem addresses will become offsettable
                       after they themselves are reloaded.  This is important;
                       we don't want our own handling of unoffsettables
                       to override the handling of reg_equiv_address.  */
                    && !(GET_CODE (XEXP (operand, 0)) == REG
                         && (ind_levels == 0
                             || reg_equiv_address[REGNO (XEXP (operand, 0))] != 0)))
                  win = 1;
                break;

                /* Memory operand whose address is offsettable.  */
              case 'o':
                if (force_reload)
                  break;
                if ((GET_CODE (operand) == MEM
                     /* If IND_LEVELS, find_reloads_address won't reload a
                        pseudo that didn't get a hard reg, so we have to
                        reject that case.  */
                     && (ind_levels ? offsettable_memref_p (operand)
                         : offsettable_nonstrict_memref_p (operand)))
                    /* Certain mem addresses will become offsettable
                       after they themselves are reloaded.  This is important;
                       we don't want our own handling of unoffsettables
                       to override the handling of reg_equiv_address.  */
                    || (GET_CODE (operand) == MEM
                        && GET_CODE (XEXP (operand, 0)) == REG
                        && (ind_levels == 0
                            || reg_equiv_address[REGNO (XEXP (operand, 0))] != 0))
                    || (GET_CODE (operand) == REG
                        && REGNO (operand) >= FIRST_PSEUDO_REGISTER
                        && reg_renumber[REGNO (operand)] < 0))
                  win = 1;
                if (CONSTANT_P (operand) || GET_CODE (operand) == MEM)
                  badop = 0;
                offmemok = 1;
                break;

              case '&':
                /* Output operand that is stored before the need for the
                   input operands (and their index registers) is over.  */
                earlyclobber = 1, this_earlyclobber = 1;
                break;

              case 'E':
                /* Match any floating double constant, but only if
                   we can examine the bits of it reliably.  */
                if ((HOST_FLOAT_FORMAT != TARGET_FLOAT_FORMAT
                     || HOST_BITS_PER_WIDE_INT != BITS_PER_WORD)
                    && GET_MODE (operand) != VOIDmode && ! flag_pretend_float)
                  break;
                if (GET_CODE (operand) == CONST_DOUBLE)
                  win = 1;
                break;

              case 'F':
                if (GET_CODE (operand) == CONST_DOUBLE)
                  win = 1;
                break;

              case 'G':
              case 'H':
                if (GET_CODE (operand) == CONST_DOUBLE
                    && CONST_DOUBLE_OK_FOR_LETTER_P (operand, c))
                  win = 1;
                break;

              case 's':
                if (GET_CODE (operand) == CONST_INT
                    || (GET_CODE (operand) == CONST_DOUBLE
                        && GET_MODE (operand) == VOIDmode))
                  break;
              case 'i':
                if (CONSTANT_P (operand)
#ifdef LEGITIMATE_PIC_OPERAND_P
                    && (! flag_pic || LEGITIMATE_PIC_OPERAND_P (operand))
#endif
                    )
                  win = 1;
                break;

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

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

              case 'X':
                win = 1;
                break;

              case 'g':
                if (! force_reload
                    /* A PLUS is never a valid operand, but reload can make
                       it from a register when eliminating registers.  */
                    && GET_CODE (operand) != PLUS
                    /* A SCRATCH is not a valid operand.  */
                    && GET_CODE (operand) != SCRATCH
#ifdef LEGITIMATE_PIC_OPERAND_P
                    && (! CONSTANT_P (operand) 
                        || ! flag_pic 
                        || LEGITIMATE_PIC_OPERAND_P (operand))
#endif
                    && (GENERAL_REGS == ALL_REGS
                        || GET_CODE (operand) != REG
                        || (REGNO (operand) >= FIRST_PSEUDO_REGISTER
                            && reg_renumber[REGNO (operand)] < 0)))
                  win = 1;
                /* Drop through into 'r' case */

              case 'r':
                this_alternative[i]
                  = (int) reg_class_subunion[this_alternative[i]][(int) GENERAL_REGS];
                goto reg;

#ifdef EXTRA_CONSTRAINT
              case 'Q':
              case 'R':
              case 'S':
              case 'T':
              case 'U':
                if (EXTRA_CONSTRAINT (operand, c))
                  win = 1;
                break;
#endif
  
              default:
                this_alternative[i]
                  = (int) reg_class_subunion[this_alternative[i]][(int) REG_CLASS_FROM_LETTER (c)];
                
              reg:
                if (GET_MODE (operand) == BLKmode)
                  break;
                winreg = 1;
                if (GET_CODE (operand) == REG
                    && reg_fits_class_p (operand, this_alternative[i],
                                         offset, GET_MODE (recog_operand[i])))
                  win = 1;
                break;
              }

          constraints[i] = p;

          /* If this operand could be handled with a reg,
             and some reg is allowed, then this operand can be handled.  */
          if (winreg && this_alternative[i] != (int) NO_REGS)
            badop = 0;

          /* Record which operands fit this alternative.  */
          this_alternative_earlyclobber[i] = earlyclobber;
          if (win && ! force_reload)
            this_alternative_win[i] = 1;
          else
            {
              this_alternative_offmemok[i] = offmemok;
              losers++;
              if (badop)
                bad = 1;
              /* Alternative loses if it has no regs for a reg operand.  */
              if (GET_CODE (operand) == REG
                  && this_alternative[i] == (int) NO_REGS
                  && this_alternative_matches[i] < 0)
                bad = 1;

              /* Alternative loses if it requires a type of reload not
                 permitted for this insn.  We can always reload SCRATCH
                 and objects with a REG_UNUSED note.  */
              if (GET_CODE (operand) != SCRATCH && modified[i] != RELOAD_READ
                  && no_output_reloads
                  && ! find_reg_note (insn, REG_UNUSED, operand))
                bad = 1;
              else if (modified[i] != RELOAD_WRITE && no_input_reloads)
                bad = 1;

              /* We prefer to reload pseudos over reloading other things,
                 since such reloads may be able to be eliminated later.
                 If we are reloading a SCRATCH, we won't be generating any
                 insns, just using a register, so it is also preferred. 
                 So bump REJECT in other cases.  */
              if (GET_CODE (operand) != REG && GET_CODE (operand) != SCRATCH)
                reject++;
            }

          /* If this operand is a pseudo register that didn't get a hard 
             reg and this alternative accepts some register, see if the
             class that we want is a subset of the preferred class for this
             register.  If not, but it intersects that class, use the
             preferred class instead.  If it does not intersect the preferred
             class, show that usage of this alternative should be discouraged;
             it will be discouraged more still if the register is `preferred
             or nothing'.  We do this because it increases the chance of
             reusing our spill register in a later insn and avoiding a pair
             of memory stores and loads.

             Don't bother with this if this alternative will accept this
             operand.

             Don't do this for a multiword operand, if
             we have to worry about small classes, because making reg groups
             harder to allocate is asking for trouble.

             Don't do this if the preferred class has only one register
             because we might otherwise exhaust the class.  */


          if (! win && this_alternative[i] != (int) NO_REGS
#ifdef SMALL_REGISTER_CLASSES
              && GET_MODE_SIZE (operand_mode[i]) <= UNITS_PER_WORD
#endif
              && reg_class_size[(int) preferred_class[i]] > 1)
            {
              if (! reg_class_subset_p (this_alternative[i],
                                        preferred_class[i]))
                {
                  /* Since we don't have a way of forming the intersection,
                     we just do something special if the preferred class
                     is a subset of the class we have; that's the most 
                     common case anyway.  */
                  if (reg_class_subset_p (preferred_class[i],
                                          this_alternative[i]))
                    this_alternative[i] = (int) preferred_class[i];
                  else
                    reject += (1 + pref_or_nothing[i]);
                }
            }
        }

      /* Now see if any output operands that are marked "earlyclobber"
         in this alternative conflict with any input operands
         or any memory addresses.  */

      for (i = 0; i < noperands; i++)
        if (this_alternative_earlyclobber[i]
            && this_alternative_win[i])
          {
            struct decomposition early_data; 
            int j;

            early_data = decompose (recog_operand[i]);

            if (modified[i] == RELOAD_READ)
              {
                if (this_insn_is_asm)
                  warning_for_asm (this_insn,
                                   "`&' constraint used with input operand");
                else
                  abort ();
                continue;
              }
            
            if (this_alternative[i] == NO_REGS)
              {
                this_alternative_earlyclobber[i] = 0;
                if (this_insn_is_asm)
                  error_for_asm (this_insn,
                                 "`&' constraint used with no register class");
                else
                  abort ();
              }

            for (j = 0; j < noperands; j++)
              /* Is this an input operand or a memory ref?  */
              if ((GET_CODE (recog_operand[j]) == MEM
                   || modified[j] != RELOAD_WRITE)
                  && j != i
                  /* Ignore things like match_operator operands.  */
                  && *constraints1[j] != 0
                  /* Don't count an input operand that is constrained to match
                     the early clobber operand.  */
                  && ! (this_alternative_matches[j] == i
                        && rtx_equal_p (recog_operand[i], recog_operand[j]))
                  /* Is it altered by storing the earlyclobber operand?  */
                  && !immune_p (recog_operand[j], recog_operand[i], early_data))
                {
                  /* If the output is in a single-reg class,
                     it's costly to reload it, so reload the input instead.  */
                  if (reg_class_size[this_alternative[i]] == 1
                      && (GET_CODE (recog_operand[j]) == REG
                          || GET_CODE (recog_operand[j]) == SUBREG))
                    {
                      losers++;
                      this_alternative_win[j] = 0;
                    }
                  else
                    break;
                }
            /* If an earlyclobber operand conflicts with something,
               it must be reloaded, so request this and count the cost.  */
            if (j != noperands)
              {
                losers++;
                this_alternative_win[i] = 0;
                for (j = 0; j < noperands; j++)
                  if (this_alternative_matches[j] == i
                      && this_alternative_win[j])
                    {
                      this_alternative_win[j] = 0;
                      losers++;
                    }
              }
          }

      /* If one alternative accepts all the operands, no reload required,
         choose that alternative; don't consider the remaining ones.  */
      if (losers == 0)
        {
          /* Unswap these so that they are never swapped at `finish'.  */
          if (commutative >= 0)
            {
              recog_operand[commutative] = substed_operand[commutative];
              recog_operand[commutative + 1]
                = substed_operand[commutative + 1];
            }
          for (i = 0; i < noperands; i++)
            {
              goal_alternative_win[i] = 1;
              goal_alternative[i] = this_alternative[i];
              goal_alternative_offmemok[i] = this_alternative_offmemok[i];
              goal_alternative_matches[i] = this_alternative_matches[i];
              goal_alternative_earlyclobber[i]
                = this_alternative_earlyclobber[i];
            }
          goal_alternative_number = this_alternative_number;
          goal_alternative_swapped = swapped;
          goal_earlyclobber = this_earlyclobber;
          goto finish;
        }

      /* REJECT, set by the ! and ? constraint characters and when a register
         would be reloaded into a non-preferred class, discourages the use of
         this alternative for a reload goal.  REJECT is incremented by three
         for each ? and one for each non-preferred class.  */
      losers = losers * 3 + reject;

      /* If this alternative can be made to work by reloading,
         and it needs less reloading than the others checked so far,
         record it as the chosen goal for reloading.  */
      if (! bad && best > losers)
        {
          for (i = 0; i < noperands; i++)
            {
              goal_alternative[i] = this_alternative[i];
              goal_alternative_win[i] = this_alternative_win[i];
              goal_alternative_offmemok[i] = this_alternative_offmemok[i];
              goal_alternative_matches[i] = this_alternative_matches[i];
              goal_alternative_earlyclobber[i]
                = this_alternative_earlyclobber[i];
            }
          goal_alternative_swapped = swapped;
          best = losers;
          goal_alternative_number = this_alternative_number;
          goal_earlyclobber = this_earlyclobber;
        }
    }

  /* If insn is commutative (it's safe to exchange a certain pair of operands)
     then we need to try each alternative twice,
     the second time matching those two operands
     as if we had exchanged them.
     To do this, really exchange them in operands.

     If we have just tried the alternatives the second time,
     return operands to normal and drop through.  */

  if (commutative >= 0)
    {
      swapped = !swapped;
      if (swapped)
        {
          register enum reg_class tclass;
          register int t;

          recog_operand[commutative] = substed_operand[commutative + 1];
          recog_operand[commutative + 1] = substed_operand[commutative];

          tclass = preferred_class[commutative];
          preferred_class[commutative] = preferred_class[commutative + 1];
          preferred_class[commutative + 1] = tclass;

          t = pref_or_nothing[commutative];
          pref_or_nothing[commutative] = pref_or_nothing[commutative + 1];
          pref_or_nothing[commutative + 1] = t;

          bcopy (constraints1, constraints, noperands * sizeof (char *));
          goto try_swapped;
        }
      else
        {
          recog_operand[commutative] = substed_operand[commutative];
          recog_operand[commutative + 1] = substed_operand[commutative + 1];
        }
    }

  /* The operands don't meet the constraints.
     goal_alternative describes the alternative
     that we could reach by reloading the fewest operands.
     Reload so as to fit it.  */

  if (best == MAX_RECOG_OPERANDS + 300)
    {
      /* No alternative works with reloads??  */
      if (insn_code_number >= 0)
        abort ();
      error_for_asm (insn, "inconsistent operand constraints in an `asm'");
      /* Avoid further trouble with this insn.  */
      PATTERN (insn) = gen_rtx (USE, VOIDmode, const0_rtx);
      n_reloads = 0;
      return;
    }

  /* Jump to `finish' from above if all operands are valid already.
     In that case, goal_alternative_win is all 1.  */
 finish:

  /* Right now, for any pair of operands I and J that are required to match,
     with I < J,
     goal_alternative_matches[J] is I.
     Set up goal_alternative_matched as the inverse function:
     goal_alternative_matched[I] = J.  */

  for (i = 0; i < noperands; i++)
    goal_alternative_matched[i] = -1;

  for (i = 0; i < noperands; i++)
    if (! goal_alternative_win[i]
        && goal_alternative_matches[i] >= 0)
      goal_alternative_matched[goal_alternative_matches[i]] = i;

  /* If the best alternative is with operands 1 and 2 swapped,
     consider them swapped before reporting the reloads.  */

  if (goal_alternative_swapped)
    {
      register rtx tem;

      tem = substed_operand[commutative];
      substed_operand[commutative] = substed_operand[commutative + 1];
      substed_operand[commutative + 1] = tem;
      tem = recog_operand[commutative];
      recog_operand[commutative] = recog_operand[commutative + 1];
      recog_operand[commutative + 1] = tem;
    }

  /* Perform whatever substitutions on the operands we are supposed
     to make due to commutativity or replacement of registers
     with equivalent constants or memory slots.  */

  for (i = 0; i < noperands; i++)
    {
      *recog_operand_loc[i] = substed_operand[i];
      /* While we are looping on operands, initialize this.  */
      operand_reloadnum[i] = -1;
    }

  /* Any constants that aren't allowed and can't be reloaded
     into registers are here changed into memory references.  */
  for (i = 0; i < noperands; i++)
    if (! goal_alternative_win[i]
        && CONSTANT_P (recog_operand[i])
        && (PREFERRED_RELOAD_CLASS (recog_operand[i],
                                    (enum reg_class) goal_alternative[i])
            == NO_REGS)
        && operand_mode[i] != VOIDmode)
      {
        *recog_operand_loc[i] = recog_operand[i]
          = find_reloads_toplev (force_const_mem (operand_mode[i],
                                                  recog_operand[i]),
                                 ind_levels, 0);
        if (alternative_allows_memconst (constraints1[i],
                                         goal_alternative_number))
          goal_alternative_win[i] = 1;
      }

  /* Now record reloads for all the operands that need them.  */
  for (i = 0; i < noperands; i++)
    if (! goal_alternative_win[i])
      {
        /* Operands that match previous ones have already been handled.  */
        if (goal_alternative_matches[i] >= 0)
          ;
        /* Handle an operand with a nonoffsettable address
           appearing where an offsettable address will do
           by reloading the address into a base register.  */
        else if (goal_alternative_matched[i] == -1
                 && goal_alternative_offmemok[i]
                 && GET_CODE (recog_operand[i]) == MEM)
          {
            operand_reloadnum[i]
              = push_reload (XEXP (recog_operand[i], 0), NULL_RTX,
                             &XEXP (recog_operand[i], 0), NULL_PTR,
                             BASE_REG_CLASS, GET_MODE (XEXP (recog_operand[i], 0)),
                             VOIDmode, 0, 0, NULL_RTX);
            reload_inc[operand_reloadnum[i]]
              = GET_MODE_SIZE (GET_MODE (recog_operand[i]));
          }
        else if (goal_alternative_matched[i] == -1)
          operand_reloadnum[i] =
            push_reload (modified[i] != RELOAD_WRITE ? recog_operand[i] : 0,
                         modified[i] != RELOAD_READ ? recog_operand[i] : 0,
                         modified[i] != RELOAD_WRITE ? recog_operand_loc[i] : 0,
                         modified[i] != RELOAD_READ ? recog_operand_loc[i] : 0,
                         (enum reg_class) goal_alternative[i],
                         (modified[i] == RELOAD_WRITE ? VOIDmode : operand_mode[i]),
                         (modified[i] == RELOAD_READ ? VOIDmode : operand_mode[i]),
                         (insn_code_number < 0 ? 0
                          : insn_operand_strict_low[insn_code_number][i]),
                         0, NULL_RTX);
        /* In a matching pair of operands, one must be input only
           and the other must be output only.
           Pass the input operand as IN and the other as OUT.  */
        else if (modified[i] == RELOAD_READ
                 && modified[goal_alternative_matched[i]] == RELOAD_WRITE)
          {
            operand_reloadnum[i]
              = push_reload (recog_operand[i],
                             recog_operand[goal_alternative_matched[i]],
                             recog_operand_loc[i],
                             recog_operand_loc[goal_alternative_matched[i]],
                             (enum reg_class) goal_alternative[i],
                             operand_mode[i],
                             operand_mode[goal_alternative_matched[i]],
                             0, 0, NULL_RTX);
            operand_reloadnum[goal_alternative_matched[i]] = output_reloadnum;
          }
        else if (modified[i] == RELOAD_WRITE
                 && modified[goal_alternative_matched[i]] == RELOAD_READ)
          {
            operand_reloadnum[goal_alternative_matched[i]]
              = push_reload (recog_operand[goal_alternative_matched[i]],
                             recog_operand[i],
                             recog_operand_loc[goal_alternative_matched[i]],
                             recog_operand_loc[i],
                             (enum reg_class) goal_alternative[i],
                             operand_mode[goal_alternative_matched[i]],
                             operand_mode[i],
                             0, 0, NULL_RTX);
            operand_reloadnum[i] = output_reloadnum;
          }
        else if (insn_code_number >= 0)
          abort ();
        else
          {
            error_for_asm (insn, "inconsistent operand constraints in an `asm'");
            /* Avoid further trouble with this insn.  */
            PATTERN (insn) = gen_rtx (USE, VOIDmode, const0_rtx);
            n_reloads = 0;
            return;
          }
      }
    else if (goal_alternative_matched[i] < 0
             && goal_alternative_matches[i] < 0
             && optimize)
      {
        rtx operand = recog_operand[i];
        /* For each non-matching operand that's a pseudo-register 
           that didn't get a hard register, make an optional reload.
           This may get done even if the insn needs no reloads otherwise.  */
        /* (It would be safe to make an optional reload for a matching pair
           of operands, but we don't bother yet.)  */
        while (GET_CODE (operand) == SUBREG)
          operand = XEXP (operand, 0);
        if (GET_CODE (operand) == REG
            && REGNO (operand) >= FIRST_PSEUDO_REGISTER
            && reg_renumber[REGNO (operand)] < 0
            && (enum reg_class) goal_alternative[i] != NO_REGS
            /* Don't make optional output reloads for jump insns
               (such as aobjeq on the vax).  */
            && (modified[i] == RELOAD_READ
                || GET_CODE (insn) != JUMP_INSN))
          operand_reloadnum[i]
            = push_reload (modified[i] != RELOAD_WRITE ? recog_operand[i] : 0,
                           modified[i] != RELOAD_READ ? recog_operand[i] : 0,
                           modified[i] != RELOAD_WRITE ? recog_operand_loc[i] : 0,
                           modified[i] != RELOAD_READ ? recog_operand_loc[i] : 0,
                           (enum reg_class) goal_alternative[i],
                           (modified[i] == RELOAD_WRITE ? VOIDmode : operand_mode[i]),
                           (modified[i] == RELOAD_READ ? VOIDmode : operand_mode[i]),
                           (insn_code_number < 0 ? 0
                            : insn_operand_strict_low[insn_code_number][i]),
                           1, NULL_RTX);
        /* Make an optional reload for an explicit mem ref.  */
        else if (GET_CODE (operand) == MEM
                 && (enum reg_class) goal_alternative[i] != NO_REGS
                 /* Don't make optional output reloads for jump insns
                    (such as aobjeq on the vax).  */
                 && (modified[i] == RELOAD_READ
                     || GET_CODE (insn) != JUMP_INSN))
          operand_reloadnum[i]
            = push_reload (modified[i] != RELOAD_WRITE ? recog_operand[i] : 0,
                           modified[i] != RELOAD_READ ? recog_operand[i] : 0,
                           modified[i] != RELOAD_WRITE ? recog_operand_loc[i] : 0,
                           modified[i] != RELOAD_READ ? recog_operand_loc[i] : 0,
                           (enum reg_class) goal_alternative[i],
                           (modified[i] == RELOAD_WRITE ? VOIDmode : operand_mode[i]),
                           (modified[i] == RELOAD_READ ? VOIDmode : operand_mode[i]),
                           (insn_code_number < 0 ? 0
                            : insn_operand_strict_low[insn_code_number][i]),
                           1, NULL_RTX);
        else
          non_reloaded_operands[n_non_reloaded_operands++] = recog_operand[i];
      }
    else if (goal_alternative_matched[i] < 0
             && goal_alternative_matches[i] < 0)
      non_reloaded_operands[n_non_reloaded_operands++] = recog_operand[i];

  /* Record the values of the earlyclobber operands for the caller.  */
  if (goal_earlyclobber)
    for (i = 0; i < noperands; i++)
      if (goal_alternative_earlyclobber[i])
        reload_earlyclobbers[n_earlyclobbers++] = recog_operand[i];

  /* If this insn pattern contains any MATCH_DUP's, make sure that
     they will be substituted if the operands they match are substituted.
     Also do now any substitutions we already did on the operands.

     Don't do this if we aren't making replacements because we might be
     propagating things allocated by frame pointer elimination into places
     it doesn't expect.  */

  if (insn_code_number >= 0 && replace)
    for (i = insn_n_dups[insn_code_number] - 1; i >= 0; i--)
      {
        int opno = recog_dup_num[i];
        *recog_dup_loc[i] = *recog_operand_loc[opno];
        if (operand_reloadnum[opno] >= 0)
          push_replacement (recog_dup_loc[i], operand_reloadnum[opno],
                            insn_operand_mode[insn_code_number][opno]);
      }

#if 0
  /* This loses because reloading of prior insns can invalidate the equivalence
     (or at least find_equiv_reg isn't smart enough to find it any more),
     causing this insn to need more reload regs than it needed before.
     It may be too late to make the reload regs available.
     Now this optimization is done safely in choose_reload_regs.  */

  /* For each reload of a reg into some other class of reg,
     search for an existing equivalent reg (same value now) in the right class.
     We can use it as long as we don't need to change its contents.  */
  for (i = 0; i < n_reloads; i++)
    if (reload_reg_rtx[i] == 0
        && reload_in[i] != 0
        && GET_CODE (reload_in[i]) == REG
        && reload_out[i] == 0)
      {
        reload_reg_rtx[i]
          = find_equiv_reg (reload_in[i], insn, reload_reg_class[i], -1,
                            static_reload_reg_p, 0, reload_inmode[i]);
        /* Prevent generation of insn to load the value
           because the one we found already has the value.  */
        if (reload_reg_rtx[i])
          reload_in[i] = reload_reg_rtx[i];
      }
#endif

#else /* no REGISTER_CONSTRAINTS */
  int noperands;
  int insn_code_number;
  int goal_earlyclobber = 0; /* Always 0, to make combine_reloads happen.  */
  register int i;
  rtx body = PATTERN (insn);

  n_reloads = 0;
  n_replacements = 0;
  n_earlyclobbers = 0;
  replace_reloads = replace;
  this_insn = insn;

  /* Find what kind of insn this is.  NOPERANDS gets number of operands.
     Store the operand values in RECOG_OPERAND and the locations
     of the words in the insn that point to them in RECOG_OPERAND_LOC.
     Return if the insn needs no reload processing.  */

  switch (GET_CODE (body))
    {
    case USE:
    case CLOBBER:
    case ASM_INPUT:
    case ADDR_VEC:
    case ADDR_DIFF_VEC:
      return;

    case PARALLEL:
    case SET:
      noperands = asm_noperands (body);
      if (noperands >= 0)
        {
          /* This insn is an `asm' with operands.
             First, find out how many operands, and allocate space.  */

          insn_code_number = -1;
          /* ??? This is a bug! ???
             Give up and delete this insn if it has too many operands.  */
          if (noperands > MAX_RECOG_OPERANDS)
            abort ();

          /* Now get the operand values out of the insn.  */

          decode_asm_operands (body, recog_operand, recog_operand_loc,
                               NULL_PTR, NULL_PTR);
          break;
        }

    default:
      /* Ordinary insn: recognize it, allocate space for operands and
         constraints, and get them out via insn_extract.  */

      insn_code_number = recog_memoized (insn);
      noperands = insn_n_operands[insn_code_number];
      insn_extract (insn);
    }

  if (noperands == 0)
    return;

  for (i = 0; i < noperands; i++)
    {
      register RTX_CODE code = GET_CODE (recog_operand[i]);
      int is_set_dest = GET_CODE (body) == SET && (i == 0);

      if (insn_code_number >= 0)
        if (insn_operand_address_p[insn_code_number][i])
          find_reloads_address (VOIDmode, NULL_PTR,
                                recog_operand[i], recog_operand_loc[i],
                                recog_operand[i], ind_levels);
      if (code == MEM)
        find_reloads_address (GET_MODE (recog_operand[i]),
                              recog_operand_loc[i],
                              XEXP (recog_operand[i], 0),
                              &XEXP (recog_operand[i], 0),
                              recog_operand[i], ind_levels);
      if (code == SUBREG)
        recog_operand[i] = *recog_operand_loc[i]
          = find_reloads_toplev (recog_operand[i], ind_levels, is_set_dest);
      if (code == REG)
        {
          register int regno = REGNO (recog_operand[i]);
          if (reg_equiv_constant[regno] != 0 && !is_set_dest)
            recog_operand[i] = *recog_operand_loc[i]
              = reg_equiv_constant[regno];
#if 0 /* This might screw code in reload1.c to delete prior output-reload
         that feeds this insn.  */
          if (reg_equiv_mem[regno] != 0)
            recog_operand[i] = *recog_operand_loc[i]
              = reg_equiv_mem[regno];
#endif
        }
      /* All operands are non-reloaded.  */
      non_reloaded_operands[n_non_reloaded_operands++] = recog_operand[i];
    }
#endif /* no REGISTER_CONSTRAINTS */

  /* Determine which part of the insn each reload is needed for,
     based on which operand the reload is needed for.
     Reloads of entire operands are classified as RELOAD_OTHER.
     So are reloads for which a unique purpose is not known.  */

  for (i = 0; i < n_reloads; i++)
    {
      reload_when_needed[i] = RELOAD_OTHER;

      if (reload_needed_for[i] != 0 && ! reload_needed_for_multiple[i])
        {
          int j;
          int output_address = 0;
          int input_address = 0;
          int operand_address = 0;

          /* This reload is needed only for the address of something.
             Determine whether it is needed for addressing an operand
             being reloaded for input, whether it is needed for an
             operand being reloaded for output, and whether it is needed
             for addressing an operand that won't really be reloaded.

             Note that we know that this reload is needed in only one address,
             but we have not yet checked for the case where that same address
             is used in both input and output reloads.
             The following code detects this case.  */

          for (j = 0; j < n_reloads; j++)
            if (reload_needed_for[i] == reload_in[j]
                || reload_needed_for[i] == reload_out[j])
              {
                if (reload_optional[j])
                  operand_address = 1;
                else
                  {
                    if (reload_needed_for[i] == reload_in[j])
                      input_address = 1;
                    if (reload_needed_for[i] == reload_out[j])
                      output_address = 1;
                  }
              }
          /* Don't ignore memrefs without optional reloads.  */
          for (j = 0; j < n_non_reloaded_operands; j++)
            if (reload_needed_for[i] == non_reloaded_operands[j])
              operand_address = 1;

          /* If it is needed for only one of those, record which one.  */

          if (input_address && ! output_address && ! operand_address)
            reload_when_needed[i] = RELOAD_FOR_INPUT_RELOAD_ADDRESS;
          if (output_address && ! input_address && ! operand_address)
            reload_when_needed[i] = RELOAD_FOR_OUTPUT_RELOAD_ADDRESS;
          if (operand_address && ! input_address && ! output_address)
            reload_when_needed[i] = RELOAD_FOR_OPERAND_ADDRESS;

          /* Indicate those RELOAD_OTHER reloads which, though they have
             0 for reload_output, still cannot overlap an output reload.  */

          if (output_address && reload_when_needed[i] == RELOAD_OTHER)
            reload_needed_for_multiple[i] = 1;

          /* If we have earlyclobbers, make sure nothing overlaps them.  */
          if (n_earlyclobbers > 0)
            {
              reload_when_needed[i] = RELOAD_OTHER;
              reload_needed_for_multiple[i] = 1;
            }
        }
    }

  /* Perhaps an output reload can be combined with another
     to reduce needs by one.  */
  if (!goal_earlyclobber)
    combine_reloads ();
}

/* Return 1 if alternative number ALTNUM in constraint-string CONSTRAINT
   accepts a memory operand with constant address.  */

static int
alternative_allows_memconst (constraint, altnum)
     char *constraint;
     int altnum;
{
  register int c;
  /* Skip alternatives before the one requested.  */
  while (altnum > 0)
    {
      while (*constraint++ != ',');
      altnum--;
    }
  /* Scan the requested alternative for 'm' or 'o'.
     If one of them is present, this alternative accepts memory constants.  */
  while ((c = *constraint++) && c != ',' && c != '#')
    if (c == 'm' || c == 'o')
      return 1;
  return 0;
}
\f
/* Scan X for memory references and scan the addresses for reloading.
   Also checks for references to "constant" regs that we want to eliminate
   and replaces them with the values they stand for.
   We may alter X destructively if it contains a reference to such.
   If X is just a constant reg, we return the equivalent value
   instead of X.

   IND_LEVELS says how many levels of indirect addressing this machine
   supports.

   IS_SET_DEST is true if X is the destination of a SET, which is not
   appropriate to be replaced by a constant.  */

static rtx
find_reloads_toplev (x, ind_levels, is_set_dest)
     rtx x;
     int ind_levels;
     int is_set_dest;
{
  register RTX_CODE code = GET_CODE (x);

  register char *fmt = GET_RTX_FORMAT (code);
  register int i;

  if (code == REG)
    {
      /* This code is duplicated for speed in find_reloads.  */
      register int regno = REGNO (x);
      if (reg_equiv_constant[regno] != 0 && !is_set_dest)
        x = reg_equiv_constant[regno];
#if 0
/*  This creates (subreg (mem...)) which would cause an unnecessary
    reload of the mem.  */
      else if (reg_equiv_mem[regno] != 0)
        x = reg_equiv_mem[regno];
#endif
      else if (reg_equiv_address[regno] != 0)
        {
          /* If reg_equiv_address varies, it may be shared, so copy it.  */
          rtx addr = reg_equiv_address[regno];

          if (rtx_varies_p (addr))
            addr = copy_rtx (addr);

          x = gen_rtx (MEM, GET_MODE (x), addr);
          RTX_UNCHANGING_P (x) = RTX_UNCHANGING_P (regno_reg_rtx[regno]);
          find_reloads_address (GET_MODE (x), NULL_PTR,
                                XEXP (x, 0),
                                &XEXP (x, 0), x, ind_levels);
        }
      return x;
    }
  if (code == MEM)
    {
      rtx tem = x;
      find_reloads_address (GET_MODE (x), &tem, XEXP (x, 0), &XEXP (x, 0),
                            x, ind_levels);
      return tem;
    }

  if (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG)
    {
      /* Check for SUBREG containing a REG that's equivalent to a constant. 
         If the constant has a known value, truncate it right now.
         Similarly if we are extracting a single-word of a multi-word
         constant.  If the constant is symbolic, allow it to be substituted
         normally.  push_reload will strip the subreg later.  If the
         constant is VOIDmode, abort because we will lose the mode of
         the register (this should never happen because one of the cases
         above should handle it).  */

      register int regno = REGNO (SUBREG_REG (x));
      rtx tem;

      if (subreg_lowpart_p (x)
          && regno >= FIRST_PSEUDO_REGISTER && reg_renumber[regno] < 0
          && reg_equiv_constant[regno] != 0
          && (tem = gen_lowpart_common (GET_MODE (x),
                                        reg_equiv_constant[regno])) != 0)
        return tem;

      if (GET_MODE_BITSIZE (GET_MODE (x)) == BITS_PER_WORD
          && regno >= FIRST_PSEUDO_REGISTER && reg_renumber[regno] < 0
          && reg_equiv_constant[regno] != 0
          && (tem = operand_subword (reg_equiv_constant[regno],
                                     SUBREG_WORD (x), 0,
                                     GET_MODE (SUBREG_REG (x)))) != 0)
        return tem;

      if (regno >= FIRST_PSEUDO_REGISTER && reg_renumber[regno] < 0
          && reg_equiv_constant[regno] != 0
          && GET_MODE (reg_equiv_constant[regno]) == VOIDmode)
        abort ();

      /* If the subreg contains a reg that will be converted to a mem,
         convert the subreg to a narrower memref now.
         Otherwise, we would get (subreg (mem ...) ...),
         which would force reload of the mem.

         We also need to do this if there is an equivalent MEM that is
         not offsettable.  In that case, alter_subreg would produce an
         invalid address on big-endian machines.

         For machines that extend byte loads, we must not reload using
         a wider mode if we have a paradoxical SUBREG.  find_reloads will
         force a reload in that case.  So we should not do anything here.  */

      else if (regno >= FIRST_PSEUDO_REGISTER
#if defined(BYTE_LOADS_ZERO_EXTEND) || defined(BYTE_LOADS_SIGN_EXTEND)
               && (GET_MODE_SIZE (GET_MODE (x))
                   <= GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
#endif
               && (reg_equiv_address[regno] != 0
                   || (reg_equiv_mem[regno] != 0
                       && ! offsettable_memref_p (reg_equiv_mem[regno]))))
        {
          int offset = SUBREG_WORD (x) * UNITS_PER_WORD;
          rtx addr = (reg_equiv_address[regno] ? reg_equiv_address[regno]
                      : XEXP (reg_equiv_mem[regno], 0));
#if BYTES_BIG_ENDIAN
          int size;
          size = GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)));
          offset += MIN (size, UNITS_PER_WORD);
          size = GET_MODE_SIZE (GET_MODE (x));
          offset -= MIN (size, UNITS_PER_WORD);
#endif
          addr = plus_constant (addr, offset);
          x = gen_rtx (MEM, GET_MODE (x), addr);
          RTX_UNCHANGING_P (x) = RTX_UNCHANGING_P (regno_reg_rtx[regno]);
          find_reloads_address (GET_MODE (x), NULL_PTR,
                                XEXP (x, 0),
                                &XEXP (x, 0), x, ind_levels);
        }

    }

  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e')
        XEXP (x, i) = find_reloads_toplev (XEXP (x, i),
                                           ind_levels, is_set_dest);
    }
  return x;
}

static rtx
make_memloc (ad, regno)
     rtx ad;
     int regno;
{
  register int i;
  rtx tem = reg_equiv_address[regno];
  for (i = 0; i < n_memlocs; i++)
    if (rtx_equal_p (tem, XEXP (memlocs[i], 0)))
      return memlocs[i];

  /* If TEM might contain a pseudo, we must copy it to avoid
     modifying it when we do the substitution for the reload.  */
  if (rtx_varies_p (tem))
    tem = copy_rtx (tem);

  tem = gen_rtx (MEM, GET_MODE (ad), tem);
  RTX_UNCHANGING_P (tem) = RTX_UNCHANGING_P (regno_reg_rtx[regno]);
  memlocs[n_memlocs++] = tem;
  return tem;
}

/* Record all reloads needed for handling memory address AD
   which appears in *LOC in a memory reference to mode MODE
   which itself is found in location  *MEMREFLOC.
   Note that we take shortcuts assuming that no multi-reg machine mode
   occurs as part of an address.

   OPERAND is the operand of the insn within which this address appears.

   IND_LEVELS says how many levels of indirect addressing this machine
   supports.

   Value is nonzero if this address is reloaded or replaced as a whole.
   This is interesting to the caller if the address is an autoincrement.

   Note that there is no verification that the address will be valid after
   this routine does its work.  Instead, we rely on the fact that the address
   was valid when reload started.  So we need only undo things that reload
   could have broken.  These are wrong register types, pseudos not allocated
   to a hard register, and frame pointer elimination.  */

static int
find_reloads_address (mode, memrefloc, ad, loc, operand, ind_levels)
     enum machine_mode mode;
     rtx *memrefloc;
     rtx ad;
     rtx *loc;
     rtx operand;
     int ind_levels;
{
  register int regno;
  rtx tem;

  /* If the address is a register, see if it is a legitimate address and
     reload if not.  We first handle the cases where we need not reload
     or where we must reload in a non-standard way.  */

  if (GET_CODE (ad) == REG)
    {
      regno = REGNO (ad);

      if (reg_equiv_constant[regno] != 0
          && strict_memory_address_p (mode, reg_equiv_constant[regno]))
        {
          *loc = ad = reg_equiv_constant[regno];
          return 1;
        }

      else if (reg_equiv_address[regno] != 0)
        {
          tem = make_memloc (ad, regno);
          find_reloads_address (GET_MODE (tem), NULL_PTR, XEXP (tem, 0),
                                &XEXP (tem, 0), operand, ind_levels);
          push_reload (tem, NULL_RTX, loc, NULL_PTR, BASE_REG_CLASS,
                       GET_MODE (ad), VOIDmode, 0, 0,
                       operand);
          return 1;
        }

      else if (reg_equiv_mem[regno] != 0)
        {
          tem = XEXP (reg_equiv_mem[regno], 0);

          /* If we can't indirect any more, a pseudo must be reloaded.
             If the pseudo's address in its MEM is a SYMBOL_REF, it
             must be reloaded unless indirect_symref_ok.  Otherwise, it
             can be reloaded if the address is REG or REG + CONST_INT.  */

          if (ind_levels > 0
              && ! (GET_CODE (tem) == SYMBOL_REF && ! indirect_symref_ok)
              && ((GET_CODE (tem) == REG
                   && REGNO (tem) < FIRST_PSEUDO_REGISTER)
                  || (GET_CODE (tem) == PLUS
                      && GET_CODE (XEXP (tem, 0)) == REG
                      && REGNO (XEXP (tem, 0)) < FIRST_PSEUDO_REGISTER
                      && GET_CODE (XEXP (tem, 1)) == CONST_INT)))
            return 0;
        }

      /* The only remaining case where we can avoid a reload is if this is a
         hard register that is valid as a base register and which is not the
         subject of a CLOBBER in this insn.  */

      else if (regno < FIRST_PSEUDO_REGISTER && REGNO_OK_FOR_BASE_P (regno)
               && ! regno_clobbered_p (regno, this_insn))
        return 0;

      /* If we do not have one of the cases above, we must do the reload.  */
      push_reload (ad, NULL_RTX, loc, NULL_PTR, BASE_REG_CLASS,
                   GET_MODE (ad), VOIDmode, 0, 0, operand);
      return 1;
    }

  if (strict_memory_address_p (mode, ad))
    {
      /* The address appears valid, so reloads are not needed.
         But the address may contain an eliminable register.
         This can happen because a machine with indirect addressing
         may consider a pseudo register by itself a valid address even when
         it has failed to get a hard reg.
         So do a tree-walk to find and eliminate all such regs.  */

      /* But first quickly dispose of a common case.  */
      if (GET_CODE (ad) == PLUS
          && GET_CODE (XEXP (ad, 1)) == CONST_INT
          && GET_CODE (XEXP (ad, 0)) == REG
          && reg_equiv_constant[REGNO (XEXP (ad, 0))] == 0)
        return 0;

      subst_reg_equivs_changed = 0;
      *loc = subst_reg_equivs (ad);

      if (! subst_reg_equivs_changed)
        return 0;

      /* Check result for validity after substitution.  */
      if (strict_memory_address_p (mode, ad))
        return 0;
    }

  /* The address is not valid.  We have to figure out why.  One possibility
     is that it is itself a MEM.  This can happen when the frame pointer is
     being eliminated, a pseudo is not allocated to a hard register, and the
     offset between the frame and stack pointers is not its initial value.
     In that case the pseudo will have been replaced by a MEM referring to
     the stack pointer.  */
  if (GET_CODE (ad) == MEM)
    {
      /* First ensure that the address in this MEM is valid.  Then, unless
         indirect addresses are valid, reload the MEM into a register.  */
      tem = ad;
      find_reloads_address (GET_MODE (ad), &tem, XEXP (ad, 0), &XEXP (ad, 0),
                            operand, ind_levels == 0 ? 0 : ind_levels - 1);

      /* If tem was changed, then we must create a new memory reference to
         hold it and store it back into memrefloc.  */
      if (tem != ad && memrefloc)
        {
          rtx oldref = *memrefloc;
          *memrefloc = copy_rtx (*memrefloc);
          copy_replacements (tem, XEXP (*memrefloc, 0));
          loc = &XEXP (*memrefloc, 0);
          if (operand == oldref)
            operand = *memrefloc;
        }

      /* Check similar cases as for indirect addresses as above except
         that we can allow pseudos and a MEM since they should have been
         taken care of above.  */

      if (ind_levels == 0
          || (GET_CODE (XEXP (tem, 0)) == SYMBOL_REF && ! indirect_symref_ok)
          || GET_CODE (XEXP (tem, 0)) == MEM
          || ! (GET_CODE (XEXP (tem, 0)) == REG
                || (GET_CODE (XEXP (tem, 0)) == PLUS
                    && GET_CODE (XEXP (XEXP (tem, 0), 0)) == REG
                    && GET_CODE (XEXP (XEXP (tem, 0), 1)) == CONST_INT)))
        {
          /* Must use TEM here, not AD, since it is the one that will
             have any subexpressions reloaded, if needed.  */
          push_reload (tem, NULL_RTX, loc, NULL_PTR,
                       BASE_REG_CLASS, GET_MODE (tem), VOIDmode, 0,
                       0, operand);
          return 1;
        }
      else
        return 0;
    }

  /* If we have address of a stack slot but it's not valid
     (displacement is too large), compute the sum in a register.  */
  else if (GET_CODE (ad) == PLUS
           && (XEXP (ad, 0) == frame_pointer_rtx
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
               || XEXP (ad, 0) == arg_pointer_rtx
#endif
               || XEXP (ad, 0) == stack_pointer_rtx)
           && GET_CODE (XEXP (ad, 1)) == CONST_INT)
    {
      /* Unshare the MEM rtx so we can safely alter it.  */
      if (memrefloc)
        {
          rtx oldref = *memrefloc;
          *memrefloc = copy_rtx (*memrefloc);
          loc = &XEXP (*memrefloc, 0);
          if (operand == oldref)
            operand = *memrefloc;
        }
      if (double_reg_address_ok)
        {
          /* Unshare the sum as well.  */
          *loc = ad = copy_rtx (ad);
          /* Reload the displacement into an index reg.
             We assume the frame pointer or arg pointer is a base reg.  */
          find_reloads_address_part (XEXP (ad, 1), &XEXP (ad, 1),
                                     INDEX_REG_CLASS, GET_MODE (ad), operand,
                                     ind_levels);
        }
      else
        {
          /* If the sum of two regs is not necessarily valid,
             reload the sum into a base reg.
             That will at least work.  */
          find_reloads_address_part (ad, loc, BASE_REG_CLASS, Pmode,
                                     operand, ind_levels);
        }
      return 1;
    }

  /* If we have an indexed stack slot, there are three possible reasons why
     it might be invalid: The index might need to be reloaded, the address
     might have been made by frame pointer elimination and hence have a
     constant out of range, or both reasons might apply.  

     We can easily check for an index needing reload, but even if that is the
     case, we might also have an invalid constant.  To avoid making the
     conservative assumption and requiring two reloads, we see if this address
     is valid when not interpreted strictly.  If it is, the only problem is
     that the index needs a reload and find_reloads_address_1 will take care
     of it.

     There is still a case when we might generate an extra reload,
     however.  In certain cases eliminate_regs will return a MEM for a REG
     (see the code there for details).  In those cases, memory_address_p
     applied to our address will return 0 so we will think that our offset
     must be too large.  But it might indeed be valid and the only problem
     is that a MEM is present where a REG should be.  This case should be
     very rare and there doesn't seem to be any way to avoid it.

     If we decide to do something here, it must be that
     `double_reg_address_ok' is true and that this address rtl was made by
     eliminate_regs.  We generate a reload of the fp/sp/ap + constant and
     rework the sum so that the reload register will be added to the index.
     This is safe because we know the address isn't shared.

     We check for fp/ap/sp as both the first and second operand of the
     innermost PLUS.  */

  else if (GET_CODE (ad) == PLUS && GET_CODE (XEXP (ad, 1)) == CONST_INT
           && GET_CODE (XEXP (ad, 0)) == PLUS
           && (XEXP (XEXP (ad, 0), 0) == frame_pointer_rtx
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
               || XEXP (XEXP (ad, 0), 0) == arg_pointer_rtx
#endif
               || XEXP (XEXP (ad, 0), 0) == stack_pointer_rtx)
           && ! memory_address_p (mode, ad))
    {
      *loc = ad = gen_rtx (PLUS, GET_MODE (ad),
                           plus_constant (XEXP (XEXP (ad, 0), 0),
                                          INTVAL (XEXP (ad, 1))),
                           XEXP (XEXP (ad, 0), 1));
      find_reloads_address_part (XEXP (ad, 0), &XEXP (ad, 0), BASE_REG_CLASS,
                                 GET_MODE (ad), operand, ind_levels);
      find_reloads_address_1 (XEXP (ad, 1), 1, &XEXP (ad, 1), operand, 0);

      return 1;
    }
                           
  else if (GET_CODE (ad) == PLUS && GET_CODE (XEXP (ad, 1)) == CONST_INT
           && GET_CODE (XEXP (ad, 0)) == PLUS
           && (XEXP (XEXP (ad, 0), 1) == frame_pointer_rtx
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
               || XEXP (XEXP (ad, 0), 1) == arg_pointer_rtx
#endif
               || XEXP (XEXP (ad, 0), 1) == stack_pointer_rtx)
           && ! memory_address_p (mode, ad))
    {
      *loc = ad = gen_rtx (PLUS, GET_MODE (ad),
                           plus_constant (XEXP (XEXP (ad, 0), 1),
                                          INTVAL (XEXP (ad, 1))),
                           XEXP (XEXP (ad, 0), 0));
      find_reloads_address_part (XEXP (ad, 0), &XEXP (ad, 0), BASE_REG_CLASS,
                                 GET_MODE (ad), operand, ind_levels);
      find_reloads_address_1 (XEXP (ad, 1), 1, &XEXP (ad, 1), operand, 0);

      return 1;
    }
                           
  /* See if address becomes valid when an eliminable register
     in a sum is replaced.  */

  tem = ad;
  if (GET_CODE (ad) == PLUS)
    tem = subst_indexed_address (ad);
  if (tem != ad && strict_memory_address_p (mode, tem))
    {
      /* Ok, we win that way.  Replace any additional eliminable
         registers.  */

      subst_reg_equivs_changed = 0;
      tem = subst_reg_equivs (tem);

      /* Make sure that didn't make the address invalid again.  */

      if (! subst_reg_equivs_changed || strict_memory_address_p (mode, tem))
        {
          *loc = tem;
          return 0;
        }
    }

  /* If constants aren't valid addresses, reload the constant address
     into a register.  */
  if (CONSTANT_P (ad) && ! strict_memory_address_p (mode, ad))
    {
      /* If AD is in address in the constant pool, the MEM rtx may be shared.
         Unshare it so we can safely alter it.  */
      if (memrefloc && GET_CODE (ad) == SYMBOL_REF
          && CONSTANT_POOL_ADDRESS_P (ad))
        {
          rtx oldref = *memrefloc;
          *memrefloc = copy_rtx (*memrefloc);
          loc = &XEXP (*memrefloc, 0);
          if (operand == oldref)
            operand = *memrefloc;
        }

      find_reloads_address_part (ad, loc, BASE_REG_CLASS, Pmode, operand,
                                 ind_levels);
      return 1;
    }

  return find_reloads_address_1 (ad, 0, loc, operand, ind_levels);
}
\f
/* Find all pseudo regs appearing in AD
   that are eliminable in favor of equivalent values
   and do not have hard regs; replace them by their equivalents.  */

static rtx
subst_reg_equivs (ad)
     rtx ad;
{
  register RTX_CODE code = GET_CODE (ad);
  register int i;
  register char *fmt;

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

    case REG:
      {
        register int regno = REGNO (ad);

        if (reg_equiv_constant[regno] != 0)
          {
            subst_reg_equivs_changed = 1;
            return reg_equiv_constant[regno];
          }
      }
      return ad;

    case PLUS:
      /* Quickly dispose of a common case.  */
      if (XEXP (ad, 0) == frame_pointer_rtx
          && GET_CODE (XEXP (ad, 1)) == CONST_INT)
        return ad;
    }

  fmt = GET_RTX_FORMAT (code);
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    if (fmt[i] == 'e')
      XEXP (ad, i) = subst_reg_equivs (XEXP (ad, i));
  return ad;
}
\f
/* Compute the sum of X and Y, making canonicalizations assumed in an
   address, namely: sum constant integers, surround the sum of two
   constants with a CONST, put the constant as the second operand, and
   group the constant on the outermost sum.

   This routine assumes both inputs are already in canonical form.  */

rtx
form_sum (x, y)
     rtx x, y;
{
  rtx tem;

  if (GET_CODE (x) == CONST_INT)
    return plus_constant (y, INTVAL (x));
  else if (GET_CODE (y) == CONST_INT)
    return plus_constant (x, INTVAL (y));
  else if (CONSTANT_P (x))
    tem = x, x = y, y = tem;

  if (GET_CODE (x) == PLUS && CONSTANT_P (XEXP (x, 1)))
    return form_sum (XEXP (x, 0), form_sum (XEXP (x, 1), y));

  /* Note that if the operands of Y are specified in the opposite
     order in the recursive calls below, infinite recursion will occur.  */
  if (GET_CODE (y) == PLUS && CONSTANT_P (XEXP (y, 1)))
    return form_sum (form_sum (x, XEXP (y, 0)), XEXP (y, 1));

  /* If both constant, encapsulate sum.  Otherwise, just form sum.  A
     constant will have been placed second.  */
  if (CONSTANT_P (x) && CONSTANT_P (y))
    {
      if (GET_CODE (x) == CONST)
        x = XEXP (x, 0);
      if (GET_CODE (y) == CONST)
        y = XEXP (y, 0);

      return gen_rtx (CONST, VOIDmode, gen_rtx (PLUS, Pmode, x, y));
    }

  return gen_rtx (PLUS, Pmode, x, y);
}
\f
/* If ADDR is a sum containing a pseudo register that should be
   replaced with a constant (from reg_equiv_constant),
   return the result of doing so, and also apply the associative
   law so that the result is more likely to be a valid address.
   (But it is not guaranteed to be one.)

   Note that at most one register is replaced, even if more are
   replaceable.  Also, we try to put the result into a canonical form
   so it is more likely to be a valid address.

   In all other cases, return ADDR.  */

static rtx
subst_indexed_address (addr)
     rtx addr;
{
  rtx op0 = 0, op1 = 0, op2 = 0;
  rtx tem;
  int regno;

  if (GET_CODE (addr) == PLUS)
    {
      /* Try to find a register to replace.  */
      op0 = XEXP (addr, 0), op1 = XEXP (addr, 1), op2 = 0;
      if (GET_CODE (op0) == REG
          && (regno = REGNO (op0)) >= FIRST_PSEUDO_REGISTER
          && reg_renumber[regno] < 0
          && reg_equiv_constant[regno] != 0)
        op0 = reg_equiv_constant[regno];
      else if (GET_CODE (op1) == REG
          && (regno = REGNO (op1)) >= FIRST_PSEUDO_REGISTER
          && reg_renumber[regno] < 0
          && reg_equiv_constant[regno] != 0)
        op1 = reg_equiv_constant[regno];
      else if (GET_CODE (op0) == PLUS
               && (tem = subst_indexed_address (op0)) != op0)
        op0 = tem;
      else if (GET_CODE (op1) == PLUS
               && (tem = subst_indexed_address (op1)) != op1)
        op1 = tem;
      else
        return addr;

      /* Pick out up to three things to add.  */
      if (GET_CODE (op1) == PLUS)
        op2 = XEXP (op1, 1), op1 = XEXP (op1, 0);
      else if (GET_CODE (op0) == PLUS)
        op2 = op1, op1 = XEXP (op0, 1), op0 = XEXP (op0, 0);

      /* Compute the sum.  */
      if (op2 != 0)
        op1 = form_sum (op1, op2);
      if (op1 != 0)
        op0 = form_sum (op0, op1);

      return op0;
    }
  return addr;
}
\f
/* Record the pseudo registers we must reload into hard registers
   in a subexpression of a would-be memory address, X.
   (This function is not called if the address we find is strictly valid.)
   CONTEXT = 1 means we are considering regs as index regs,
   = 0 means we are considering them as base regs.

   OPERAND is the operand of the insn within which this address appears.

   IND_LEVELS says how many levels of indirect addressing are
   supported at this point in the address.

   We return nonzero if X, as a whole, is reloaded or replaced.  */

/* Note that we take shortcuts assuming that no multi-reg machine mode
   occurs as part of an address.
   Also, this is not fully machine-customizable; it works for machines
   such as vaxes and 68000's and 32000's, but other possible machines
   could have addressing modes that this does not handle right.  */

static int
find_reloads_address_1 (x, context, loc, operand, ind_levels)
     rtx x;
     int context;
     rtx *loc;
     rtx operand;
     int ind_levels;
{
  register RTX_CODE code = GET_CODE (x);

  if (code == PLUS)
    {
      register rtx op0 = XEXP (x, 0);
      register rtx op1 = XEXP (x, 1);
      register RTX_CODE code0 = GET_CODE (op0);
      register RTX_CODE code1 = GET_CODE (op1);
      if (code0 == MULT || code0 == SIGN_EXTEND || code1 == MEM)
        {
          find_reloads_address_1 (op0, 1, &XEXP (x, 0), operand, ind_levels);
          find_reloads_address_1 (op1, 0, &XEXP (x, 1), operand, ind_levels);
        }
      else if (code1 == MULT || code1 == SIGN_EXTEND || code0 == MEM)
        {
          find_reloads_address_1 (op0, 0, &XEXP (x, 0), operand, ind_levels);
          find_reloads_address_1 (op1, 1, &XEXP (x, 1), operand, ind_levels);
        }
      else if (code0 == CONST_INT || code0 == CONST
               || code0 == SYMBOL_REF || code0 == LABEL_REF)
        {
          find_reloads_address_1 (op1, 0, &XEXP (x, 1), operand, ind_levels);
        }
      else if (code1 == CONST_INT || code1 == CONST
               || code1 == SYMBOL_REF || code1 == LABEL_REF)
        {
          find_reloads_address_1 (op0, 0, &XEXP (x, 0), operand, ind_levels);
        }
      else if (code0 == REG && code1 == REG)
        {
          if (REG_OK_FOR_INDEX_P (op0)
              && REG_OK_FOR_BASE_P (op1))
            return 0;
          else if (REG_OK_FOR_INDEX_P (op1)
              && REG_OK_FOR_BASE_P (op0))
            return 0;
          else if (REG_OK_FOR_BASE_P (op1))
            find_reloads_address_1 (op0, 1, &XEXP (x, 0), operand, ind_levels);
          else if (REG_OK_FOR_BASE_P (op0))
            find_reloads_address_1 (op1, 1, &XEXP (x, 1), operand, ind_levels);
          else if (REG_OK_FOR_INDEX_P (op1))
            find_reloads_address_1 (op0, 0, &XEXP (x, 0), operand, ind_levels);
          else if (REG_OK_FOR_INDEX_P (op0))
            find_reloads_address_1 (op1, 0, &XEXP (x, 1), operand, ind_levels);
          else
            {
              find_reloads_address_1 (op0, 1, &XEXP (x, 0), operand,
                                      ind_levels);
              find_reloads_address_1 (op1, 0, &XEXP (x, 1), operand,
                                      ind_levels);
            }
        }
      else if (code0 == REG)
        {
          find_reloads_address_1 (op0, 1, &XEXP (x, 0), operand, ind_levels);
          find_reloads_address_1 (op1, 0, &XEXP (x, 1), operand, ind_levels);
        }
      else if (code1 == REG)
        {
          find_reloads_address_1 (op1, 1, &XEXP (x, 1), operand, ind_levels);
          find_reloads_address_1 (op0, 0, &XEXP (x, 0), operand, ind_levels);
        }
    }
  else if (code == POST_INC || code == POST_DEC
           || code == PRE_INC || code == PRE_DEC)
    {
      if (GET_CODE (XEXP (x, 0)) == REG)
        {
          register int regno = REGNO (XEXP (x, 0));
          int value = 0;
          rtx x_orig = x;

          /* A register that is incremented cannot be constant!  */
          if (regno >= FIRST_PSEUDO_REGISTER
              && reg_equiv_constant[regno] != 0)
            abort ();

          /* Handle a register that is equivalent to a memory location
             which cannot be addressed directly.  */
          if (reg_equiv_address[regno] != 0)
            {
              rtx tem = make_memloc (XEXP (x, 0), regno);
              /* First reload the memory location's address.  */
              find_reloads_address (GET_MODE (tem), 0, XEXP (tem, 0),
                                    &XEXP (tem, 0), operand, ind_levels);
              /* Put this inside a new increment-expression.  */
              x = gen_rtx (GET_CODE (x), GET_MODE (x), tem);
              /* Proceed to reload that, as if it contained a register.  */
            }

          /* If we have a hard register that is ok as an index,
             don't make a reload.  If an autoincrement of a nice register
             isn't "valid", it must be that no autoincrement is "valid".
             If that is true and something made an autoincrement anyway,
             this must be a special context where one is allowed.
             (For example, a "push" instruction.)
             We can't improve this address, so leave it alone.  */

          /* Otherwise, reload the autoincrement into a suitable hard reg
             and record how much to increment by.  */

          if (reg_renumber[regno] >= 0)
            regno = reg_renumber[regno];
          if ((regno >= FIRST_PSEUDO_REGISTER
               || !(context ? REGNO_OK_FOR_INDEX_P (regno)
                    : REGNO_OK_FOR_BASE_P (regno))))
            {
              register rtx link;

              int reloadnum
                = push_reload (x, NULL_RTX, loc, NULL_PTR,
                               context ? INDEX_REG_CLASS : BASE_REG_CLASS,
                               GET_MODE (x), GET_MODE (x), VOIDmode, 0, operand);
              reload_inc[reloadnum]
                = find_inc_amount (PATTERN (this_insn), XEXP (x_orig, 0));

              value = 1;

#ifdef AUTO_INC_DEC
              /* Update the REG_INC notes.  */

              for (link = REG_NOTES (this_insn);
                   link; link = XEXP (link, 1))
                if (REG_NOTE_KIND (link) == REG_INC
                    && REGNO (XEXP (link, 0)) == REGNO (XEXP (x_orig, 0)))
                  push_replacement (&XEXP (link, 0), reloadnum, VOIDmode);
#endif
            }
          return value;
        }
      else if (GET_CODE (XEXP (x, 0)) == MEM)
        {
          /* This is probably the result of a substitution, by eliminate_regs,
             of an equivalent address for a pseudo that was not allocated to a
             hard register.  Verify that the specified address is valid and
             reload it into a register.  */
          rtx tem = XEXP (x, 0);
          register rtx link;
          int reloadnum;

          /* Since we know we are going to reload this item, don't decrement
             for the indirection level.

             Note that this is actually conservative:  it would be slightly
             more efficient to use the value of SPILL_INDIRECT_LEVELS from
             reload1.c here.  */
          find_reloads_address (GET_MODE (x), &XEXP (x, 0),
                                XEXP (XEXP (x, 0), 0), &XEXP (XEXP (x, 0), 0),
                                operand, ind_levels);

          reloadnum = push_reload (x, NULL_RTX, loc, NULL_PTR,
                                   context ? INDEX_REG_CLASS : BASE_REG_CLASS,
                                   GET_MODE (x), VOIDmode, 0, 0, operand);
          reload_inc[reloadnum]
            = find_inc_amount (PATTERN (this_insn), XEXP (x, 0));

          link = FIND_REG_INC_NOTE (this_insn, tem);
          if (link != 0)
            push_replacement (&XEXP (link, 0), reloadnum, VOIDmode);

          return 1;
        }
    }
  else if (code == MEM)
    {
      /* This is probably the result of a substitution, by eliminate_regs,
         of an equivalent address for a pseudo that was not allocated to a
         hard register.  Verify that the specified address is valid and reload
         it into a register.

         Since we know we are going to reload this item, don't decrement
         for the indirection level.

         Note that this is actually conservative:  it would be slightly more
         efficient to use the value of SPILL_INDIRECT_LEVELS from
         reload1.c here.  */

      find_reloads_address (GET_MODE (x), loc, XEXP (x, 0), &XEXP (x, 0),
                            operand, ind_levels);

      push_reload (*loc, NULL_RTX, loc, NULL_PTR,
                   context ? INDEX_REG_CLASS : BASE_REG_CLASS,
                   GET_MODE (x), VOIDmode, 0, 0, operand);
      return 1;
    }
  else if (code == REG)
    {
      register int regno = REGNO (x);

      if (reg_equiv_constant[regno] != 0)
        {
          find_reloads_address_part (reg_equiv_constant[regno], loc, 
                                     (context ? INDEX_REG_CLASS
                                      : BASE_REG_CLASS),
                                     GET_MODE (x), operand, ind_levels);
          return 1;
        }

#if 0 /* This might screw code in reload1.c to delete prior output-reload
         that feeds this insn.  */
      if (reg_equiv_mem[regno] != 0)
        {
          push_reload (reg_equiv_mem[regno], NULL_RTX, loc, NULL_PTR,
                       context ? INDEX_REG_CLASS : BASE_REG_CLASS,
                       GET_MODE (x), VOIDmode, 0, 0, operand);
          return 1;
        }
#endif
      if (reg_equiv_address[regno] != 0)
        {
          x = make_memloc (x, regno);
          find_reloads_address (GET_MODE (x), 0, XEXP (x, 0), &XEXP (x, 0),
                                operand, ind_levels);
        }

      if (reg_renumber[regno] >= 0)
        regno = reg_renumber[regno];
      if ((regno >= FIRST_PSEUDO_REGISTER
           || !(context ? REGNO_OK_FOR_INDEX_P (regno)
                : REGNO_OK_FOR_BASE_P (regno))))
        {
          push_reload (x, NULL_RTX, loc, NULL_PTR,
                       context ? INDEX_REG_CLASS : BASE_REG_CLASS,
                       GET_MODE (x), VOIDmode, 0, 0, operand);
          return 1;
        }

      /* If a register appearing in an address is the subject of a CLOBBER
         in this insn, reload it into some other register to be safe.
         The CLOBBER is supposed to make the register unavailable
         from before this insn to after it.  */
      if (regno_clobbered_p (regno, this_insn))
        {
          push_reload (x, NULL_RTX, loc, NULL_PTR,
                       context ? INDEX_REG_CLASS : BASE_REG_CLASS,
                       GET_MODE (x), VOIDmode, 0, 0, operand);
          return 1;
        }
    }
  else
    {
      register char *fmt = GET_RTX_FORMAT (code);
      register int i;
      for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        {
          if (fmt[i] == 'e')
            find_reloads_address_1 (XEXP (x, i), context, &XEXP (x, i),
                                    operand, ind_levels);
        }
    }

  return 0;
}
\f
/* X, which is found at *LOC, is a part of an address that needs to be
   reloaded into a register of class CLASS.  If X is a constant, or if
   X is a PLUS that contains a constant, check that the constant is a
   legitimate operand and that we are supposed to be able to load
   it into the register.

   If not, force the constant into memory and reload the MEM instead.

   MODE is the mode to use, in case X is an integer constant.

   NEEDED_FOR says which operand this reload is needed for.

   IND_LEVELS says how many levels of indirect addressing this machine
   supports.  */

static void
find_reloads_address_part (x, loc, class, mode, needed_for, ind_levels)
     rtx x;
     rtx *loc;
     enum reg_class class;
     enum machine_mode mode;
     rtx needed_for;
     int ind_levels;
{
  if (CONSTANT_P (x)
      && (! LEGITIMATE_CONSTANT_P (x)
          || PREFERRED_RELOAD_CLASS (x, class) == NO_REGS))
    {
      rtx tem = x = force_const_mem (mode, x);
      find_reloads_address (mode, &tem, XEXP (tem, 0), &XEXP (tem, 0),
                            needed_for, ind_levels);
    }

  else if (GET_CODE (x) == PLUS
           && CONSTANT_P (XEXP (x, 1))
           && (! LEGITIMATE_CONSTANT_P (XEXP (x, 1))
               || PREFERRED_RELOAD_CLASS (XEXP (x, 1), class) == NO_REGS))
    {
      rtx tem = force_const_mem (GET_MODE (x), XEXP (x, 1));

      x = gen_rtx (PLUS, GET_MODE (x), XEXP (x, 0), tem);
      find_reloads_address (mode, &tem, XEXP (tem, 0), &XEXP (tem, 0),
                            needed_for, ind_levels);
    }

  push_reload (x, NULL_RTX, loc, NULL_PTR, class,
               mode, VOIDmode, 0, 0, needed_for);
}
\f
/* Substitute into X the registers into which we have reloaded
   the things that need reloading.  The array `replacements'
   says contains the locations of all pointers that must be changed
   and says what to replace them with.

   Return the rtx that X translates into; usually X, but modified.  */

void
subst_reloads ()
{
  register int i;

  for (i = 0; i < n_replacements; i++)
    {
      register struct replacement *r = &replacements[i];
      register rtx reloadreg = reload_reg_rtx[r->what];
      if (reloadreg)
        {
          /* Encapsulate RELOADREG so its machine mode matches what
             used to be there.  */
          if (GET_MODE (reloadreg) != r->mode && r->mode != VOIDmode)
            reloadreg = gen_rtx (REG, r->mode, REGNO (reloadreg));

          /* If we are putting this into a SUBREG and RELOADREG is a
             SUBREG, we would be making nested SUBREGs, so we have to fix
             this up.  Note that r->where == &SUBREG_REG (*r->subreg_loc).  */

          if (r->subreg_loc != 0 && GET_CODE (reloadreg) == SUBREG)
            {
              if (GET_MODE (*r->subreg_loc)
                  == GET_MODE (SUBREG_REG (reloadreg)))
                *r->subreg_loc = SUBREG_REG (reloadreg);
              else
                {
                  *r->where = SUBREG_REG (reloadreg);
                  SUBREG_WORD (*r->subreg_loc) += SUBREG_WORD (reloadreg);
                }
            }
          else
            *r->where = reloadreg;
        }
      /* If reload got no reg and isn't optional, something's wrong.  */
      else if (! reload_optional[r->what])
        abort ();
    }
}
\f
/* Make a copy of any replacements being done into X and move those copies
   to locations in Y, a copy of X.  We only look at the highest level of
   the RTL.  */

void
copy_replacements (x, y)
     rtx x;
     rtx y;
{
  int i, j;
  enum rtx_code code = GET_CODE (x);
  char *fmt = GET_RTX_FORMAT (code);
  struct replacement *r;

  /* We can't support X being a SUBREG because we might then need to know its
     location if something inside it was replaced.  */
  if (code == SUBREG)
    abort ();

  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    if (fmt[i] == 'e')
      for (j = 0; j < n_replacements; j++)
        {
          if (replacements[j].subreg_loc == &XEXP (x, i))
            {
              r = &replacements[n_replacements++];
              r->where = replacements[j].where;
              r->subreg_loc = &XEXP (y, i);
              r->what = replacements[j].what;
              r->mode = replacements[j].mode;
            }
          else if (replacements[j].where == &XEXP (x, i))
            {
              r = &replacements[n_replacements++];
              r->where = &XEXP (y, i);
              r->subreg_loc = 0;
              r->what = replacements[j].what;
              r->mode = replacements[j].mode;
            }
        }
}
\f
/* If LOC was scheduled to be replaced by something, return the replacement.
   Otherwise, return *LOC.  */

rtx
find_replacement (loc)
     rtx *loc;
{
  struct replacement *r;

  for (r = &replacements[0]; r < &replacements[n_replacements]; r++)
    {
      rtx reloadreg = reload_reg_rtx[r->what];

      if (reloadreg && r->where == loc)
        {
          if (r->mode != VOIDmode && GET_MODE (reloadreg) != r->mode)
            reloadreg = gen_rtx (REG, r->mode, REGNO (reloadreg));

          return reloadreg;
        }
      else if (reloadreg && r->subreg_loc == loc)
        {
          /* RELOADREG must be either a REG or a SUBREG.

             ??? Is it actually still ever a SUBREG?  If so, why?  */

          if (GET_CODE (reloadreg) == REG)
            return gen_rtx (REG, GET_MODE (*loc),
                            REGNO (reloadreg) + SUBREG_WORD (*loc));
          else if (GET_MODE (reloadreg) == GET_MODE (*loc))
            return reloadreg;
          else
            return gen_rtx (SUBREG, GET_MODE (*loc), SUBREG_REG (reloadreg),
                            SUBREG_WORD (reloadreg) + SUBREG_WORD (*loc));
        }
    }

  return *loc;
}
\f
/* Return nonzero if register in range [REGNO, ENDREGNO)
   appears either explicitly or implicitly in X
   other than being stored into.

   References contained within the substructure at LOC do not count.
   LOC may be zero, meaning don't ignore anything.

   This is similar to refers_to_regno_p in rtlanal.c except that we
   look at equivalences for pseudos that didn't get hard registers.  */

int
refers_to_regno_for_reload_p (regno, endregno, x, loc)
     int regno, endregno;
     rtx x;
     rtx *loc;
{
  register int i;
  register RTX_CODE code;
  register char *fmt;

  if (x == 0)
    return 0;

 repeat:
  code = GET_CODE (x);

  switch (code)
    {
    case REG:
      i = REGNO (x);

      /* If this is a pseudo, a hard register must not have been allocated.
         X must therefore either be a constant or be in memory.  */
      if (i >= FIRST_PSEUDO_REGISTER)
        {
          if (reg_equiv_memory_loc[i])
            return refers_to_regno_for_reload_p (regno, endregno,
                                                 reg_equiv_memory_loc[i],
                                                 NULL_PTR);

          if (reg_equiv_constant[i])
            return 0;

          abort ();
        }

      return (endregno > i
              && regno < i + (i < FIRST_PSEUDO_REGISTER 
                              ? HARD_REGNO_NREGS (i, GET_MODE (x))
                              : 1));

    case SUBREG:
      /* If this is a SUBREG of a hard reg, we can see exactly which
         registers are being modified.  Otherwise, handle normally.  */
      if (GET_CODE (SUBREG_REG (x)) == REG
          && REGNO (SUBREG_REG (x)) < FIRST_PSEUDO_REGISTER)
        {
          int inner_regno = REGNO (SUBREG_REG (x)) + SUBREG_WORD (x);
          int inner_endregno
            = inner_regno + (inner_regno < FIRST_PSEUDO_REGISTER
                             ? HARD_REGNO_NREGS (regno, GET_MODE (x)) : 1);

          return endregno > inner_regno && regno < inner_endregno;
        }
      break;

    case CLOBBER:
    case SET:
      if (&SET_DEST (x) != loc
          /* Note setting a SUBREG counts as referring to the REG it is in for
             a pseudo but not for hard registers since we can
             treat each word individually.  */
          && ((GET_CODE (SET_DEST (x)) == SUBREG
               && loc != &SUBREG_REG (SET_DEST (x))
               && GET_CODE (SUBREG_REG (SET_DEST (x))) == REG
               && REGNO (SUBREG_REG (SET_DEST (x))) >= FIRST_PSEUDO_REGISTER
               && refers_to_regno_for_reload_p (regno, endregno,
                                                SUBREG_REG (SET_DEST (x)),
                                                loc))
              || (GET_CODE (SET_DEST (x)) != REG
                  && refers_to_regno_for_reload_p (regno, endregno,
                                                   SET_DEST (x), loc))))
        return 1;

      if (code == CLOBBER || loc == &SET_SRC (x))
        return 0;
      x = SET_SRC (x);
      goto repeat;
    }

  /* X does not match, so try its subexpressions.  */

  fmt = GET_RTX_FORMAT (code);
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e' && loc != &XEXP (x, i))
        {
          if (i == 0)
            {
              x = XEXP (x, 0);
              goto repeat;
            }
          else
            if (refers_to_regno_for_reload_p (regno, endregno,
                                              XEXP (x, i), loc))
              return 1;
        }
      else if (fmt[i] == 'E')
        {
          register int j;
          for (j = XVECLEN (x, i) - 1; j >=0; j--)
            if (loc != &XVECEXP (x, i, j)
                && refers_to_regno_for_reload_p (regno, endregno,
                                                 XVECEXP (x, i, j), loc))
              return 1;
        }
    }
  return 0;
}

/* Nonzero if modifying X will affect IN.  If X is a register or a SUBREG,
   we check if any register number in X conflicts with the relevant register
   numbers.  If X is a constant, return 0.  If X is a MEM, return 1 iff IN
   contains a MEM (we don't bother checking for memory addresses that can't
   conflict because we expect this to be a rare case. 

   This function is similar to reg_overlap_mention_p in rtlanal.c except
   that we look at equivalences for pseudos that didn't get hard registers.  */

int
reg_overlap_mentioned_for_reload_p (x, in)
     rtx x, in;
{
  int regno, endregno;

  if (GET_CODE (x) == SUBREG)
    {
      regno = REGNO (SUBREG_REG (x));
      if (regno < FIRST_PSEUDO_REGISTER)
        regno += SUBREG_WORD (x);
    }
  else if (GET_CODE (x) == REG)
    {
      regno = REGNO (x);

      /* If this is a pseudo, it must not have been assigned a hard register.
         Therefore, it must either be in memory or be a constant.  */

      if (regno >= FIRST_PSEUDO_REGISTER)
        {
          if (reg_equiv_memory_loc[regno])
            return refers_to_mem_for_reload_p (in);
          else if (reg_equiv_constant[regno])
            return 0;
          abort ();
        }
    }
  else if (CONSTANT_P (x))
    return 0;
  else if (GET_CODE (x) == MEM)
    return refers_to_mem_for_reload_p (in);
  else if (GET_CODE (x) == SCRATCH || GET_CODE (x) == PC
           || GET_CODE (x) == CC0)
    return reg_mentioned_p (x, in);
  else
    abort ();

  endregno = regno + (regno < FIRST_PSEUDO_REGISTER
                      ? HARD_REGNO_NREGS (regno, GET_MODE (x)) : 1);

  return refers_to_regno_for_reload_p (regno, endregno, in, NULL_PTR);
}

/* Return nonzero if anything in X contains a MEM.  Look also for pseudo
   registers.  */

int
refers_to_mem_for_reload_p (x)
     rtx x;
{
  char *fmt;
  int i;

  if (GET_CODE (x) == MEM)
    return 1;

  if (GET_CODE (x) == REG)
    return (REGNO (x) >= FIRST_PSEUDO_REGISTER
            && reg_equiv_memory_loc[REGNO (x)]);
                        
  fmt = GET_RTX_FORMAT (GET_CODE (x));
  for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
    if (fmt[i] == 'e'
        && (GET_CODE (XEXP (x, i)) == MEM
            || refers_to_mem_for_reload_p (XEXP (x, i))))
      return 1;
  
  return 0;
}
\f
#if 0

/* [[This function is currently obsolete, now that volatility
   is represented by a special bit `volatil' so VOLATILE is never used;
   and UNCHANGING has never been brought into use.]]

   Alter X by eliminating all VOLATILE and UNCHANGING expressions.
   Each of them is replaced by its operand.
   Thus, (PLUS (VOLATILE (MEM (REG 5))) (CONST_INT 4))
   becomes (PLUS (MEM (REG 5)) (CONST_INT 4)).

   If X is itself a VOLATILE expression,
   we return the expression that should replace it
   but we do not modify X.  */

static rtx
forget_volatility (x)
     register rtx x;
{
  enum rtx_code code = GET_CODE (x);
  register char *fmt;
  register int i;
  register rtx value = 0;

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

    case VOLATILE:
    case UNCHANGING:
      return XEXP (x, 0);
    }

  fmt = GET_RTX_FORMAT (code);
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e')
        XEXP (x, i) = forget_volatility (XEXP (x, i));
      if (fmt[i] == 'E')
        {
          register int j;
          for (j = XVECLEN (x, i) - 1; j >= 0; j--)
            XVECEXP (x, i, j) = forget_volatility (XVECEXP (x, i, j));
        }
    }

  return x;
}

#endif
\f
/* Check the insns before INSN to see if there is a suitable register
   containing the same value as GOAL.
   If OTHER is -1, look for a register in class CLASS.
   Otherwise, just see if register number OTHER shares GOAL's value.

   Return an rtx for the register found, or zero if none is found.

   If RELOAD_REG_P is (short *)1,
   we reject any hard reg that appears in reload_reg_rtx
   because such a hard reg is also needed coming into this insn.

   If RELOAD_REG_P is any other nonzero value,
   it is a vector indexed by hard reg number
   and we reject any hard reg whose element in the vector is nonnegative
   as well as any that appears in reload_reg_rtx.

   If GOAL is zero, then GOALREG is a register number; we look
   for an equivalent for that register.

   MODE is the machine mode of the value we want an equivalence for.
   If GOAL is nonzero and not VOIDmode, then it must have mode MODE.

   This function is used by jump.c as well as in the reload pass.

   If GOAL is the sum of the stack pointer and a constant, we treat it
   as if it were a constant except that sp is required to be unchanging.  */

rtx
find_equiv_reg (goal, insn, class, other, reload_reg_p, goalreg, mode)
     register rtx goal;
     rtx insn;
     enum reg_class class;
     register int other;
     short *reload_reg_p;
     int goalreg;
     enum machine_mode mode;
{
  register rtx p = insn;
  rtx valtry, value, where;
  register rtx pat;
  register int regno = -1;
  int valueno;
  int goal_mem = 0;
  int goal_const = 0;
  int goal_mem_addr_varies = 0;
  int need_stable_sp = 0;
  int nregs;
  int valuenregs;

  if (goal == 0)
    regno = goalreg;
  else if (GET_CODE (goal) == REG)
    regno = REGNO (goal);
  else if (GET_CODE (goal) == MEM)
    {
      enum rtx_code code = GET_CODE (XEXP (goal, 0));
      if (MEM_VOLATILE_P (goal))
        return 0;
      if (flag_float_store && GET_MODE_CLASS (GET_MODE (goal)) == MODE_FLOAT)
        return 0;
      /* An address with side effects must be reexecuted.  */
      switch (code)
        {
        case POST_INC:
        case PRE_INC:
        case POST_DEC:
        case PRE_DEC:
          return 0;
        }
      goal_mem = 1;
    }
  else if (CONSTANT_P (goal))
    goal_const = 1;
  else if (GET_CODE (goal) == PLUS
           && XEXP (goal, 0) == stack_pointer_rtx
           && CONSTANT_P (XEXP (goal, 1)))
    goal_const = need_stable_sp = 1;
  else
    return 0;

  /* On some machines, certain regs must always be rejected
     because they don't behave the way ordinary registers do.  */
  
#ifdef OVERLAPPING_REGNO_P
   if (regno >= 0 && regno < FIRST_PSEUDO_REGISTER
       && OVERLAPPING_REGNO_P (regno))
     return 0;
#endif      

  /* Scan insns back from INSN, looking for one that copies
     a value into or out of GOAL.
     Stop and give up if we reach a label.  */

  while (1)
    {
      p = PREV_INSN (p);
      if (p == 0 || GET_CODE (p) == CODE_LABEL)
        return 0;
      if (GET_CODE (p) == INSN
          /* If we don't want spill regs ... */
          && (! (reload_reg_p != 0 && reload_reg_p != (short *)1)
          /* ... then ignore insns introduced by reload; they aren't useful
             and can cause results in reload_as_needed to be different
             from what they were when calculating the need for spills.
             If we notice an input-reload insn here, we will reject it below,
             but it might hide a usable equivalent.  That makes bad code.
             It may even abort: perhaps no reg was spilled for this insn
             because it was assumed we would find that equivalent.  */
              || INSN_UID (p) < reload_first_uid))
        {
          rtx tem;
          pat = single_set (p);
          /* First check for something that sets some reg equal to GOAL.  */
          if (pat != 0
              && ((regno >= 0
                   && true_regnum (SET_SRC (pat)) == regno
                   && (valueno = true_regnum (valtry = SET_DEST (pat))) >= 0)
                  ||
                  (regno >= 0
                   && true_regnum (SET_DEST (pat)) == regno
                   && (valueno = true_regnum (valtry = SET_SRC (pat))) >= 0)
                  ||
                  (goal_const && rtx_equal_p (SET_SRC (pat), goal)
                   && (valueno = true_regnum (valtry = SET_DEST (pat))) >= 0)
                  || (goal_mem
                      && (valueno = true_regnum (valtry = SET_DEST (pat))) >= 0
                      && rtx_renumbered_equal_p (goal, SET_SRC (pat)))
                  || (goal_mem
                      && (valueno = true_regnum (valtry = SET_SRC (pat))) >= 0
                      && rtx_renumbered_equal_p (goal, SET_DEST (pat)))
                  /* If we are looking for a constant,
                     and something equivalent to that constant was copied
                     into a reg, we can use that reg.  */
                  || (goal_const && (tem = find_reg_note (p, REG_EQUIV,
                                                          NULL_RTX))
                      && rtx_equal_p (XEXP (tem, 0), goal)
                      && (valueno = true_regnum (valtry = SET_DEST (pat))) >= 0)
                  || (goal_const && (tem = find_reg_note (p, REG_EQUIV,
                                                          NULL_RTX))
                      && GET_CODE (SET_DEST (pat)) == REG
                      && GET_CODE (XEXP (tem, 0)) == CONST_DOUBLE
                      && GET_MODE_CLASS (GET_MODE (XEXP (tem, 0))) == MODE_FLOAT
                      && GET_CODE (goal) == CONST_INT
                      && INTVAL (goal) == CONST_DOUBLE_LOW (XEXP (tem, 0))
                      && (valtry = operand_subword (SET_DEST (pat), 0, 0,
                                                    VOIDmode))
                      && (valueno = true_regnum (valtry)) >= 0)
                  || (goal_const && (tem = find_reg_note (p, REG_EQUIV,
                                                          NULL_RTX))
                      && GET_CODE (SET_DEST (pat)) == REG
                      && GET_CODE (XEXP (tem, 0)) == CONST_DOUBLE
                      && GET_MODE_CLASS (GET_MODE (XEXP (tem, 0))) == MODE_FLOAT
                      && GET_CODE (goal) == CONST_INT
                      && INTVAL (goal) == CONST_DOUBLE_HIGH (XEXP (tem, 0))
                      && (valtry
                          = operand_subword (SET_DEST (pat), 1, 0, VOIDmode))
                      && (valueno = true_regnum (valtry)) >= 0)))
            if (other >= 0
                ? valueno == other
                : ((unsigned) valueno < FIRST_PSEUDO_REGISTER
                   && TEST_HARD_REG_BIT (reg_class_contents[(int) class],
                                         valueno)))
              {
                value = valtry;
                where = p;
                break;
              }
        }
    }

  /* We found a previous insn copying GOAL into a suitable other reg VALUE
     (or copying VALUE into GOAL, if GOAL is also a register).
     Now verify that VALUE is really valid.  */

  /* VALUENO is the register number of VALUE; a hard register.  */

  /* Don't try to re-use something that is killed in this insn.  We want
     to be able to trust REG_UNUSED notes.  */
  if (find_reg_note (where, REG_UNUSED, value))
    return 0;

  /* If we propose to get the value from the stack pointer or if GOAL is
     a MEM based on the stack pointer, we need a stable SP.  */
  if (valueno == STACK_POINTER_REGNUM
      || (goal_mem && reg_overlap_mentioned_for_reload_p (stack_pointer_rtx,
                                                          goal)))
    need_stable_sp = 1;

  /* Reject VALUE if the copy-insn moved the wrong sort of datum.  */
  if (GET_MODE (value) != mode)
    return 0;

  /* Reject VALUE if it was loaded from GOAL
     and is also a register that appears in the address of GOAL.  */

  if (goal_mem && value == SET_DEST (PATTERN (where))
      && refers_to_regno_for_reload_p (valueno,
                                       (valueno
                                        + HARD_REGNO_NREGS (valueno, mode)),
                                       goal, NULL_PTR))
    return 0;

  /* Reject registers that overlap GOAL.  */

  if (!goal_mem && !goal_const
      && regno + HARD_REGNO_NREGS (regno, mode) > valueno
      && regno < valueno + HARD_REGNO_NREGS (valueno, mode))
    return 0;

  /* Reject VALUE if it is one of the regs reserved for reloads.
     Reload1 knows how to reuse them anyway, and it would get
     confused if we allocated one without its knowledge.
     (Now that insns introduced by reload are ignored above,
     this case shouldn't happen, but I'm not positive.)  */

  if (reload_reg_p != 0 && reload_reg_p != (short *)1
      && reload_reg_p[valueno] >= 0)
    return 0;

  /* On some machines, certain regs must always be rejected
     because they don't behave the way ordinary registers do.  */
  
#ifdef OVERLAPPING_REGNO_P
  if (OVERLAPPING_REGNO_P (valueno))
    return 0;
#endif      

  nregs = HARD_REGNO_NREGS (regno, mode);
  valuenregs = HARD_REGNO_NREGS (valueno, mode);

  /* Reject VALUE if it is a register being used for an input reload
     even if it is not one of those reserved.  */

  if (reload_reg_p != 0)
    {
      int i;
      for (i = 0; i < n_reloads; i++)
        if (reload_reg_rtx[i] != 0 && reload_in[i])
          {
            int regno1 = REGNO (reload_reg_rtx[i]);
            int nregs1 = HARD_REGNO_NREGS (regno1,
                                           GET_MODE (reload_reg_rtx[i]));
            if (regno1 < valueno + valuenregs
                && regno1 + nregs1 > valueno)
              return 0;
          }
    }

  if (goal_mem)
    goal_mem_addr_varies = rtx_addr_varies_p (goal);

  /* Now verify that the values of GOAL and VALUE remain unaltered
     until INSN is reached.  */

  p = insn;
  while (1)
    {
      p = PREV_INSN (p);
      if (p == where)
        return value;

      /* Don't trust the conversion past a function call
         if either of the two is in a call-clobbered register, or memory.  */
      if (GET_CODE (p) == CALL_INSN
          && ((regno >= 0 && regno < FIRST_PSEUDO_REGISTER
               && call_used_regs[regno])
              ||
              (valueno >= 0 && valueno < FIRST_PSEUDO_REGISTER
               && call_used_regs[valueno])
              ||
              goal_mem
              || need_stable_sp))
        return 0;

#ifdef INSN_CLOBBERS_REGNO_P
      if ((valueno >= 0 && valueno < FIRST_PSEUDO_REGISTER
          && INSN_CLOBBERS_REGNO_P (p, valueno))
          || (regno >= 0 && regno < FIRST_PSEUDO_REGISTER
          && INSN_CLOBBERS_REGNO_P (p, regno)))
        return 0;
#endif

      if (GET_RTX_CLASS (GET_CODE (p)) == 'i')
        {
          /* If this insn P stores in either GOAL or VALUE, return 0.
             If GOAL is a memory ref and this insn writes memory, return 0.
             If GOAL is a memory ref and its address is not constant,
             and this insn P changes a register used in GOAL, return 0.  */

          pat = PATTERN (p);
          if (GET_CODE (pat) == SET || GET_CODE (pat) == CLOBBER)
            {
              register rtx dest = SET_DEST (pat);
              while (GET_CODE (dest) == SUBREG
                     || GET_CODE (dest) == ZERO_EXTRACT
                     || GET_CODE (dest) == SIGN_EXTRACT
                     || GET_CODE (dest) == STRICT_LOW_PART)
                dest = XEXP (dest, 0);
              if (GET_CODE (dest) == REG)
                {
                  register int xregno = REGNO (dest);
                  int xnregs;
                  if (REGNO (dest) < FIRST_PSEUDO_REGISTER)
                    xnregs = HARD_REGNO_NREGS (xregno, GET_MODE (dest));
                  else
                    xnregs = 1;
                  if (xregno < regno + nregs && xregno + xnregs > regno)
                    return 0;
                  if (xregno < valueno + valuenregs
                      && xregno + xnregs > valueno)
                    return 0;
                  if (goal_mem_addr_varies
                      && reg_overlap_mentioned_for_reload_p (dest, goal))
                    return 0;
                }
              else if (goal_mem && GET_CODE (dest) == MEM
                       && ! push_operand (dest, GET_MODE (dest)))
                return 0;
              else if (need_stable_sp && push_operand (dest, GET_MODE (dest)))
                return 0;
            }
          else if (GET_CODE (pat) == PARALLEL)
            {
              register int i;
              for (i = XVECLEN (pat, 0) - 1; i >= 0; i--)
                {
                  register rtx v1 = XVECEXP (pat, 0, i);
                  if (GET_CODE (v1) == SET || GET_CODE (v1) == CLOBBER)
                    {
                      register rtx dest = SET_DEST (v1);
                      while (GET_CODE (dest) == SUBREG
                             || GET_CODE (dest) == ZERO_EXTRACT
                             || GET_CODE (dest) == SIGN_EXTRACT
                             || GET_CODE (dest) == STRICT_LOW_PART)
                        dest = XEXP (dest, 0);
                      if (GET_CODE (dest) == REG)
                        {
                          register int xregno = REGNO (dest);
                          int xnregs;
                          if (REGNO (dest) < FIRST_PSEUDO_REGISTER)
                            xnregs = HARD_REGNO_NREGS (xregno, GET_MODE (dest));
                          else
                            xnregs = 1;
                          if (xregno < regno + nregs
                              && xregno + xnregs > regno)
                            return 0;
                          if (xregno < valueno + valuenregs
                              && xregno + xnregs > valueno)
                            return 0;
                          if (goal_mem_addr_varies
                              && reg_overlap_mentioned_for_reload_p (dest,
                                                                     goal))
                            return 0;
                        }
                      else if (goal_mem && GET_CODE (dest) == MEM
                               && ! push_operand (dest, GET_MODE (dest)))
                        return 0;
                      else if (need_stable_sp
                               && push_operand (dest, GET_MODE (dest)))
                        return 0;
                    }
                }
            }

#ifdef AUTO_INC_DEC
          /* If this insn auto-increments or auto-decrements
             either regno or valueno, return 0 now.
             If GOAL is a memory ref and its address is not constant,
             and this insn P increments a register used in GOAL, return 0.  */
          {
            register rtx link;

            for (link = REG_NOTES (p); link; link = XEXP (link, 1))
              if (REG_NOTE_KIND (link) == REG_INC
                  && GET_CODE (XEXP (link, 0)) == REG)
                {
                  register int incno = REGNO (XEXP (link, 0));
                  if (incno < regno + nregs && incno >= regno)
                    return 0;
                  if (incno < valueno + valuenregs && incno >= valueno)
                    return 0;
                  if (goal_mem_addr_varies
                      && reg_overlap_mentioned_for_reload_p (XEXP (link, 0),
                                                             goal))
                    return 0;
                }
          }
#endif
        }
    }
}
\f
/* Find a place where INCED appears in an increment or decrement operator
   within X, and return the amount INCED is incremented or decremented by.
   The value is always positive.  */

static int
find_inc_amount (x, inced)
     rtx x, inced;
{
  register enum rtx_code code = GET_CODE (x);
  register char *fmt;
  register int i;

  if (code == MEM)
    {
      register rtx addr = XEXP (x, 0);
      if ((GET_CODE (addr) == PRE_DEC
           || GET_CODE (addr) == POST_DEC
           || GET_CODE (addr) == PRE_INC
           || GET_CODE (addr) == POST_INC)
          && XEXP (addr, 0) == inced)
        return GET_MODE_SIZE (GET_MODE (x));
    }

  fmt = GET_RTX_FORMAT (code);
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e')
        {
          register int tem = find_inc_amount (XEXP (x, i), inced);
          if (tem != 0)
            return tem;
        }
      if (fmt[i] == 'E')
        {
          register int j;
          for (j = XVECLEN (x, i) - 1; j >= 0; j--)
            {
              register int tem = find_inc_amount (XVECEXP (x, i, j), inced);
              if (tem != 0)
                return tem;
            }
        }
    }

  return 0;
}
\f
/* Return 1 if register REGNO is the subject of a clobber in insn INSN.  */

int
regno_clobbered_p (regno, insn)
     int regno;
     rtx insn;
{
  if (GET_CODE (PATTERN (insn)) == CLOBBER
      && GET_CODE (XEXP (PATTERN (insn), 0)) == REG)
    return REGNO (XEXP (PATTERN (insn), 0)) == regno;

  if (GET_CODE (PATTERN (insn)) == PARALLEL)
    {
      int i = XVECLEN (PATTERN (insn), 0) - 1;

      for (; i >= 0; i--)
        {
          rtx elt = XVECEXP (PATTERN (insn), 0, i);
          if (GET_CODE (elt) == CLOBBER && GET_CODE (XEXP (elt, 0)) == REG
              && REGNO (XEXP (elt, 0)) == regno)
            return 1;
        }
    }

  return 0;
}