path: root/gcc/genemit.c

/* Generate code from machine description to emit insns as rtl.
   Copyright (C) 1987, 1988, 1991, 1994, 1995, 1997, 1998, 1999, 2000, 2001,
   2003, 2004, 2005 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.  */


#include "bconfig.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "rtl.h"
#include "errors.h"
#include "gensupport.h"


static int max_opno;
static int max_dup_opno;
static int max_scratch_opno;
static int insn_code_number;
static int insn_index_number;

/* Data structure for recording the patterns of insns that have CLOBBERs.
   We use this to output a function that adds these CLOBBERs to a
   previously-allocated PARALLEL expression.  */

struct clobber_pat
{
  struct clobber_ent *insns;
  rtx pattern;
  int first_clobber;
  struct clobber_pat *next;
  int has_hard_reg;
} *clobber_list;

/* Records one insn that uses the clobber list.  */

struct clobber_ent
{
  int code_number;		/* Counts only insns.  */
  struct clobber_ent *next;
};

static void max_operand_1		(rtx);
static int max_operand_vec		(rtx, int);
static void print_code			(RTX_CODE);
static void gen_exp			(rtx, enum rtx_code, char *);
static void gen_insn			(rtx, int);
static void gen_expand			(rtx);
static void gen_split			(rtx);
static void output_add_clobbers		(void);
static void output_added_clobbers_hard_reg_p (void);
static void gen_rtx_scratch		(rtx, enum rtx_code);
static void output_peephole2_scratches	(rtx);


static void
max_operand_1 (rtx x)
{
  RTX_CODE code;
  int i;
  int len;
  const char *fmt;

  if (x == 0)
    return;

  code = GET_CODE (x);

  if (code == MATCH_OPERAND || code == MATCH_OPERATOR
      || code == MATCH_PARALLEL)
    max_opno = MAX (max_opno, XINT (x, 0));
  if (code == MATCH_DUP || code == MATCH_OP_DUP || code == MATCH_PAR_DUP)
    max_dup_opno = MAX (max_dup_opno, XINT (x, 0));
  if (code == MATCH_SCRATCH)
    max_scratch_opno = MAX (max_scratch_opno, XINT (x, 0));

  fmt = GET_RTX_FORMAT (code);
  len = GET_RTX_LENGTH (code);
  for (i = 0; i < len; i++)
    {
      if (fmt[i] == 'e' || fmt[i] == 'u')
	max_operand_1 (XEXP (x, i));
      else if (fmt[i] == 'E')
	{
	  int j;
	  for (j = 0; j < XVECLEN (x, i); j++)
	    max_operand_1 (XVECEXP (x, i, j));
	}
    }
}

static int
max_operand_vec (rtx insn, int arg)
{
  int len = XVECLEN (insn, arg);
  int i;

  max_opno = -1;
  max_dup_opno = -1;
  max_scratch_opno = -1;

  for (i = 0; i < len; i++)
    max_operand_1 (XVECEXP (insn, arg, i));

  return max_opno + 1;
}

static void
print_code (RTX_CODE code)
{
  const char *p1;
  for (p1 = GET_RTX_NAME (code); *p1; p1++)
    putchar (TOUPPER(*p1));
}

static void
gen_rtx_scratch (rtx x, enum rtx_code subroutine_type)
{
  if (subroutine_type == DEFINE_PEEPHOLE2)
    {
      printf ("operand%d", XINT (x, 0));
    }
  else
    {
      printf ("gen_rtx_SCRATCH (%smode)", GET_MODE_NAME (GET_MODE (x)));
    }
}

/* Print a C expression to construct an RTX just like X,
   substituting any operand references appearing within.  */

static void
gen_exp (rtx x, enum rtx_code subroutine_type, char *used)
{
  RTX_CODE code;
  int i;
  int len;
  const char *fmt;

  if (x == 0)
    {
      printf ("NULL_RTX");
      return;
    }

  code = GET_CODE (x);

  switch (code)
    {
    case MATCH_OPERAND:
    case MATCH_DUP:
      if (used)
	{
	  if (used[XINT (x, 0)])
	    {
	      printf ("copy_rtx (operand%d)", XINT (x, 0));
	      return;
	    }
	  used[XINT (x, 0)] = 1;
	}
      printf ("operand%d", XINT (x, 0));
      return;

    case MATCH_OP_DUP:
      printf ("gen_rtx_fmt_");
      for (i = 0; i < XVECLEN (x, 1); i++)
	printf ("e");
      printf (" (GET_CODE (operand%d), ", XINT (x, 0));
      if (GET_MODE (x) == VOIDmode)
	printf ("GET_MODE (operand%d)", XINT (x, 0));
      else
	printf ("%smode", GET_MODE_NAME (GET_MODE (x)));
      for (i = 0; i < XVECLEN (x, 1); i++)
	{
	  printf (",\n\t\t");
	  gen_exp (XVECEXP (x, 1, i), subroutine_type, used);
	}
      printf (")");
      return;

    case MATCH_OPERATOR:
      printf ("gen_rtx_fmt_");
      for (i = 0; i < XVECLEN (x, 2); i++)
	printf ("e");
      printf (" (GET_CODE (operand%d)", XINT (x, 0));
      printf (", %smode", GET_MODE_NAME (GET_MODE (x)));
      for (i = 0; i < XVECLEN (x, 2); i++)
	{
	  printf (",\n\t\t");
	  gen_exp (XVECEXP (x, 2, i), subroutine_type, used);
	}
      printf (")");
      return;

    case MATCH_PARALLEL:
    case MATCH_PAR_DUP:
      printf ("operand%d", XINT (x, 0));
      return;

    case MATCH_SCRATCH:
      gen_rtx_scratch (x, subroutine_type);
      return;

    case ADDRESS:
      fatal ("ADDRESS expression code used in named instruction pattern");

    case PC:
      printf ("pc_rtx");
      return;
    case CLOBBER:
      if (REG_P (XEXP (x, 0)))
	{
	  printf ("gen_hard_reg_clobber (%smode, %i)", GET_MODE_NAME (GET_MODE (XEXP (x, 0))),
			  			     REGNO (XEXP (x, 0)));
	  return;
	}
      break;

    case CC0:
      printf ("cc0_rtx");
      return;

    case CONST_INT:
      if (INTVAL (x) == 0)
	printf ("const0_rtx");
      else if (INTVAL (x) == 1)
	printf ("const1_rtx");
      else if (INTVAL (x) == -1)
	printf ("constm1_rtx");
      else if (-MAX_SAVED_CONST_INT <= INTVAL (x)
	  && INTVAL (x) <= MAX_SAVED_CONST_INT)
	printf ("const_int_rtx[MAX_SAVED_CONST_INT + (%d)]",
		(int) INTVAL (x));
      else if (INTVAL (x) == STORE_FLAG_VALUE)
	printf ("const_true_rtx");
      else
	{
	  printf ("GEN_INT (");
	  printf (HOST_WIDE_INT_PRINT_DEC_C, INTVAL (x));
	  printf (")");
	}
      return;

    case CONST_DOUBLE:
      /* These shouldn't be written in MD files.  Instead, the appropriate
	 routines in varasm.c should be called.  */
      gcc_unreachable ();

    default:
      break;
    }

  printf ("gen_rtx_");
  print_code (code);
  printf (" (%smode", GET_MODE_NAME (GET_MODE (x)));

  fmt = GET_RTX_FORMAT (code);
  len = GET_RTX_LENGTH (code);
  for (i = 0; i < len; i++)
    {
      if (fmt[i] == '0')
	break;
      printf (",\n\t");
      switch (fmt[i])
	{
	case 'e': case 'u':
	  gen_exp (XEXP (x, i), subroutine_type, used);
	  break;

	case 'i':
	  printf ("%u", XINT (x, i));
	  break;

	case 's':
	  printf ("\"%s\"", XSTR (x, i));
	  break;

	case 'E':
	  {
	    int j;
	    printf ("gen_rtvec (%d", XVECLEN (x, i));
	    for (j = 0; j < XVECLEN (x, i); j++)
	      {
		printf (",\n\t\t");
		gen_exp (XVECEXP (x, i, j), subroutine_type, used);
	      }
	    printf (")");
	    break;
	  }

	default:
	  gcc_unreachable ();
	}
    }
  printf (")");
}

/* Generate the `gen_...' function for a DEFINE_INSN.  */

static void
gen_insn (rtx insn, int lineno)
{
  int operands;
  int i;

  /* See if the pattern for this insn ends with a group of CLOBBERs of (hard)
     registers or MATCH_SCRATCHes.  If so, store away the information for
     later.  */

  if (XVEC (insn, 1))
    {
      int has_hard_reg = 0;

      for (i = XVECLEN (insn, 1) - 1; i > 0; i--)
	{
	  if (GET_CODE (XVECEXP (insn, 1, i)) != CLOBBER)
	    break;

	  if (REG_P (XEXP (XVECEXP (insn, 1, i), 0)))
	    has_hard_reg = 1;
	  else if (GET_CODE (XEXP (XVECEXP (insn, 1, i), 0)) != MATCH_SCRATCH)
	    break;
	}

      if (i != XVECLEN (insn, 1) - 1)
	{
	  struct clobber_pat *p;
	  struct clobber_ent *link = XNEW (struct clobber_ent);
	  int j;

	  link->code_number = insn_code_number;

	  /* See if any previous CLOBBER_LIST entry is the same as this
	     one.  */

	  for (p = clobber_list; p; p = p->next)
	    {
	      if (p->first_clobber != i + 1
		  || XVECLEN (p->pattern, 1) != XVECLEN (insn, 1))
		continue;

	      for (j = i + 1; j < XVECLEN (insn, 1); j++)
		{
		  rtx old = XEXP (XVECEXP (p->pattern, 1, j), 0);
		  rtx new = XEXP (XVECEXP (insn, 1, j), 0);

		  /* OLD and NEW are the same if both are to be a SCRATCH
		     of the same mode,
		     or if both are registers of the same mode and number.  */
		  if (! (GET_MODE (old) == GET_MODE (new)
			 && ((GET_CODE (old) == MATCH_SCRATCH
			      && GET_CODE (new) == MATCH_SCRATCH)
			     || (REG_P (old) && REG_P (new)
				 && REGNO (old) == REGNO (new)))))
		    break;
		}

	      if (j == XVECLEN (insn, 1))
		break;
	    }

	  if (p == 0)
	    {
	      p = XNEW (struct clobber_pat);

	      p->insns = 0;
	      p->pattern = insn;
	      p->first_clobber = i + 1;
	      p->next = clobber_list;
	      p->has_hard_reg = has_hard_reg;
	      clobber_list = p;
	    }

	  link->next = p->insns;
	  p->insns = link;
	}
    }

  /* Don't mention instructions whose names are the null string
     or begin with '*'.  They are in the machine description just
     to be recognized.  */
  if (XSTR (insn, 0)[0] == 0 || XSTR (insn, 0)[0] == '*')
    return;

  printf ("/* %s:%d */\n", read_rtx_filename, lineno);

  /* Find out how many operands this function has.  */
  operands = max_operand_vec (insn, 1);
  if (max_dup_opno >= operands)
    fatal ("match_dup operand number has no match_operand");

  /* Output the function name and argument declarations.  */
  printf ("rtx\ngen_%s (", XSTR (insn, 0));
  if (operands)
    for (i = 0; i < operands; i++)
      if (i)
	printf (",\n\trtx operand%d ATTRIBUTE_UNUSED", i);
      else
	printf ("rtx operand%d ATTRIBUTE_UNUSED", i);
  else
    printf ("void");
  printf (")\n");
  printf ("{\n");

  /* Output code to construct and return the rtl for the instruction body.  */

  if (XVECLEN (insn, 1) == 1)
    {
      printf ("  return ");
      gen_exp (XVECEXP (insn, 1, 0), DEFINE_INSN, NULL);
      printf (";\n}\n\n");
    }
  else
    {
      printf ("  return gen_rtx_PARALLEL (VOIDmode, gen_rtvec (%d",
	      XVECLEN (insn, 1));

      for (i = 0; i < XVECLEN (insn, 1); i++)
	{
	  printf (",\n\t\t");
	  gen_exp (XVECEXP (insn, 1, i), DEFINE_INSN, NULL);
	}
      printf ("));\n}\n\n");
    }
}

/* Generate the `gen_...' function for a DEFINE_EXPAND.  */

static void
gen_expand (rtx expand)
{
  int operands;
  int i;

  if (strlen (XSTR (expand, 0)) == 0)
    fatal ("define_expand lacks a name");
  if (XVEC (expand, 1) == 0)
    fatal ("define_expand for %s lacks a pattern", XSTR (expand, 0));

  /* Find out how many operands this function has.  */
  operands = max_operand_vec (expand, 1);

  /* Output the function name and argument declarations.  */
  printf ("rtx\ngen_%s (", XSTR (expand, 0));
  if (operands)
    for (i = 0; i < operands; i++)
      if (i)
	printf (",\n\trtx operand%d", i);
      else
	printf ("rtx operand%d", i);
  else
    printf ("void");
  printf (")\n");
  printf ("{\n");

  /* If we don't have any C code to write, only one insn is being written,
     and no MATCH_DUPs are present, we can just return the desired insn
     like we do for a DEFINE_INSN.  This saves memory.  */
  if ((XSTR (expand, 3) == 0 || *XSTR (expand, 3) == '\0')
      && operands > max_dup_opno
      && XVECLEN (expand, 1) == 1)
    {
      printf ("  return ");
      gen_exp (XVECEXP (expand, 1, 0), DEFINE_EXPAND, NULL);
      printf (";\n}\n\n");
      return;
    }

  /* For each operand referred to only with MATCH_DUPs,
     make a local variable.  */
  for (i = operands; i <= max_dup_opno; i++)
    printf ("  rtx operand%d;\n", i);
  for (; i <= max_scratch_opno; i++)
    printf ("  rtx operand%d ATTRIBUTE_UNUSED;\n", i);
  printf ("  rtx _val = 0;\n");
  printf ("  start_sequence ();\n");

  /* The fourth operand of DEFINE_EXPAND is some code to be executed
     before the actual construction.
     This code expects to refer to `operands'
     just as the output-code in a DEFINE_INSN does,
     but here `operands' is an automatic array.
     So copy the operand values there before executing it.  */
  if (XSTR (expand, 3) && *XSTR (expand, 3))
    {
      printf ("  {\n");
      if (operands > 0 || max_dup_opno >= 0 || max_scratch_opno >= 0)
	printf ("    rtx operands[%d];\n",
	    MAX (operands, MAX (max_scratch_opno, max_dup_opno) + 1));
      /* Output code to copy the arguments into `operands'.  */
      for (i = 0; i < operands; i++)
	printf ("    operands[%d] = operand%d;\n", i, i);

      /* Output the special code to be executed before the sequence
	 is generated.  */
      print_rtx_ptr_loc (XSTR (expand, 3));
      printf ("%s\n", XSTR (expand, 3));

      /* Output code to copy the arguments back out of `operands'
	 (unless we aren't going to use them at all).  */
      if (XVEC (expand, 1) != 0)
	{
	  for (i = 0; i < operands; i++)
	    printf ("    operand%d = operands[%d];\n", i, i);
	  for (; i <= max_dup_opno; i++)
	    printf ("    operand%d = operands[%d];\n", i, i);
	  for (; i <= max_scratch_opno; i++)
	    printf ("    operand%d = operands[%d];\n", i, i);
	}
      printf ("  }\n");
    }

  /* Output code to construct the rtl for the instruction bodies.
     Use emit_insn to add them to the sequence being accumulated.
     But don't do this if the user's code has set `no_more' nonzero.  */

  for (i = 0; i < XVECLEN (expand, 1); i++)
    {
      rtx next = XVECEXP (expand, 1, i);
      if ((GET_CODE (next) == SET && GET_CODE (SET_DEST (next)) == PC)
	  || (GET_CODE (next) == PARALLEL
	      && ((GET_CODE (XVECEXP (next, 0, 0)) == SET
		   && GET_CODE (SET_DEST (XVECEXP (next, 0, 0))) == PC)
		  || GET_CODE (XVECEXP (next, 0, 0)) == RETURN))
	  || GET_CODE (next) == RETURN)
	printf ("  emit_jump_insn (");
      else if ((GET_CODE (next) == SET && GET_CODE (SET_SRC (next)) == CALL)
	       || GET_CODE (next) == CALL
	       || (GET_CODE (next) == PARALLEL
		   && GET_CODE (XVECEXP (next, 0, 0)) == SET
		   && GET_CODE (SET_SRC (XVECEXP (next, 0, 0))) == CALL)
	       || (GET_CODE (next) == PARALLEL
		   && GET_CODE (XVECEXP (next, 0, 0)) == CALL))
	printf ("  emit_call_insn (");
      else if (LABEL_P (next))
	printf ("  emit_label (");
      else if (GET_CODE (next) == MATCH_OPERAND
	       || GET_CODE (next) == MATCH_DUP
	       || GET_CODE (next) == MATCH_OPERATOR
	       || GET_CODE (next) == MATCH_OP_DUP
	       || GET_CODE (next) == MATCH_PARALLEL
	       || GET_CODE (next) == MATCH_PAR_DUP
	       || GET_CODE (next) == PARALLEL)
	printf ("  emit (");
      else
	printf ("  emit_insn (");
      gen_exp (next, DEFINE_EXPAND, NULL);
      printf (");\n");
      if (GET_CODE (next) == SET && GET_CODE (SET_DEST (next)) == PC
	  && GET_CODE (SET_SRC (next)) == LABEL_REF)
	printf ("  emit_barrier ();");
    }

  /* Call `get_insns' to extract the list of all the
     insns emitted within this gen_... function.  */

  printf ("  _val = get_insns ();\n");
  printf ("  end_sequence ();\n");
  printf ("  return _val;\n}\n\n");
}

/* Like gen_expand, but generates insns resulting from splitting SPLIT.  */

static void
gen_split (rtx split)
{
  int i;
  int operands;
  const char *const name =
    ((GET_CODE (split) == DEFINE_PEEPHOLE2) ? "peephole2" : "split");
  const char *unused;
  char *used;

  if (XVEC (split, 0) == 0)
    fatal ("define_%s (definition %d) lacks a pattern", name,
	   insn_index_number);
  else if (XVEC (split, 2) == 0)
    fatal ("define_%s (definition %d) lacks a replacement pattern", name,
	   insn_index_number);

  /* Find out how many operands this function has.  */

  max_operand_vec (split, 2);
  operands = MAX (max_opno, MAX (max_dup_opno, max_scratch_opno)) + 1;
  unused = (operands == 0 ? " ATTRIBUTE_UNUSED" : "");
  used = XCNEWVEC (char, operands);

  /* Output the prototype, function name and argument declarations.  */
  if (GET_CODE (split) == DEFINE_PEEPHOLE2)
    {
      printf ("extern rtx gen_%s_%d (rtx, rtx *);\n",
	      name, insn_code_number);
      printf ("rtx\ngen_%s_%d (rtx curr_insn ATTRIBUTE_UNUSED, rtx *operands%s)\n",
	      name, insn_code_number, unused);
    }
  else
    {
      printf ("extern rtx gen_split_%d (rtx, rtx *);\n", insn_code_number);
      printf ("rtx\ngen_split_%d (rtx curr_insn ATTRIBUTE_UNUSED, rtx *operands%s)\n", 
	      insn_code_number, unused);
    }
  printf ("{\n");

  /* Declare all local variables.  */
  for (i = 0; i < operands; i++)
    printf ("  rtx operand%d;\n", i);
  printf ("  rtx _val = 0;\n");

  if (GET_CODE (split) == DEFINE_PEEPHOLE2)
    output_peephole2_scratches (split);

  printf ("  start_sequence ();\n");

  /* The fourth operand of DEFINE_SPLIT is some code to be executed
     before the actual construction.  */

  if (XSTR (split, 3))
    {
      print_rtx_ptr_loc (XSTR (split, 3));
      printf ("%s\n", XSTR (split, 3));
    }

  /* Output code to copy the arguments back out of `operands'  */
  for (i = 0; i < operands; i++)
    printf ("  operand%d = operands[%d];\n", i, i);

  /* Output code to construct the rtl for the instruction bodies.
     Use emit_insn to add them to the sequence being accumulated.
     But don't do this if the user's code has set `no_more' nonzero.  */

  for (i = 0; i < XVECLEN (split, 2); i++)
    {
      rtx next = XVECEXP (split, 2, i);
      if ((GET_CODE (next) == SET && GET_CODE (SET_DEST (next)) == PC)
	  || (GET_CODE (next) == PARALLEL
	      && GET_CODE (XVECEXP (next, 0, 0)) == SET
	      && GET_CODE (SET_DEST (XVECEXP (next, 0, 0))) == PC)
	  || GET_CODE (next) == RETURN)
	printf ("  emit_jump_insn (");
      else if ((GET_CODE (next) == SET && GET_CODE (SET_SRC (next)) == CALL)
	       || GET_CODE (next) == CALL
	       || (GET_CODE (next) == PARALLEL
		   && GET_CODE (XVECEXP (next, 0, 0)) == SET
		   && GET_CODE (SET_SRC (XVECEXP (next, 0, 0))) == CALL)
	       || (GET_CODE (next) == PARALLEL
		   && GET_CODE (XVECEXP (next, 0, 0)) == CALL))
	printf ("  emit_call_insn (");
      else if (LABEL_P (next))
	printf ("  emit_label (");
      else if (GET_CODE (next) == MATCH_OPERAND
	       || GET_CODE (next) == MATCH_OPERATOR
	       || GET_CODE (next) == MATCH_PARALLEL
	       || GET_CODE (next) == MATCH_OP_DUP
	       || GET_CODE (next) == MATCH_DUP
	       || GET_CODE (next) == PARALLEL)
	printf ("  emit (");
      else
	printf ("  emit_insn (");
      gen_exp (next, GET_CODE (split), used);
      printf (");\n");
      if (GET_CODE (next) == SET && GET_CODE (SET_DEST (next)) == PC
	  && GET_CODE (SET_SRC (next)) == LABEL_REF)
	printf ("  emit_barrier ();");
    }

  /* Call `get_insns' to make a list of all the
     insns emitted within this gen_... function.  */

  printf ("  _val = get_insns ();\n");
  printf ("  end_sequence ();\n");
  printf ("  return _val;\n}\n\n");

  free (used);
}

/* Write a function, `add_clobbers', that is given a PARALLEL of sufficient
   size for the insn and an INSN_CODE, and inserts the required CLOBBERs at
   the end of the vector.  */

static void
output_add_clobbers (void)
{
  struct clobber_pat *clobber;
  struct clobber_ent *ent;
  int i;

  printf ("\n\nvoid\nadd_clobbers (rtx pattern ATTRIBUTE_UNUSED, int insn_code_number)\n");
  printf ("{\n");
  printf ("  switch (insn_code_number)\n");
  printf ("    {\n");

  for (clobber = clobber_list; clobber; clobber = clobber->next)
    {
      for (ent = clobber->insns; ent; ent = ent->next)
	printf ("    case %d:\n", ent->code_number);

      for (i = clobber->first_clobber; i < XVECLEN (clobber->pattern, 1); i++)
	{
	  printf ("      XVECEXP (pattern, 0, %d) = ", i);
	  gen_exp (XVECEXP (clobber->pattern, 1, i),
		   GET_CODE (clobber->pattern), NULL);
	  printf (";\n");
	}

      printf ("      break;\n\n");
    }

  printf ("    default:\n");
  printf ("      gcc_unreachable ();\n");
  printf ("    }\n");
  printf ("}\n");
}

/* Write a function, `added_clobbers_hard_reg_p' that is given an insn_code
   number that will have clobbers added (as indicated by `recog') and returns
   1 if those include a clobber of a hard reg or 0 if all of them just clobber
   SCRATCH.  */

static void
output_added_clobbers_hard_reg_p (void)
{
  struct clobber_pat *clobber;
  struct clobber_ent *ent;
  int clobber_p, used;

  printf ("\n\nint\nadded_clobbers_hard_reg_p (int insn_code_number)\n");
  printf ("{\n");
  printf ("  switch (insn_code_number)\n");
  printf ("    {\n");

  for (clobber_p = 0; clobber_p <= 1; clobber_p++)
    {
      used = 0;
      for (clobber = clobber_list; clobber; clobber = clobber->next)
	if (clobber->has_hard_reg == clobber_p)
	  for (ent = clobber->insns; ent; ent = ent->next)
	    {
	      printf ("    case %d:\n", ent->code_number);
	      used++;
	    }

      if (used)
	printf ("      return %d;\n\n", clobber_p);
    }

  printf ("    default:\n");
  printf ("      gcc_unreachable ();\n");
  printf ("    }\n");
  printf ("}\n");
}

/* Generate code to invoke find_free_register () as needed for the
   scratch registers used by the peephole2 pattern in SPLIT.  */

static void
output_peephole2_scratches (rtx split)
{
  int i;
  int insn_nr = 0;

  printf ("  HARD_REG_SET _regs_allocated;\n");
  printf ("  CLEAR_HARD_REG_SET (_regs_allocated);\n");

  for (i = 0; i < XVECLEN (split, 0); i++)
    {
      rtx elt = XVECEXP (split, 0, i);
      if (GET_CODE (elt) == MATCH_SCRATCH)
	{
	  int last_insn_nr = insn_nr;
	  int cur_insn_nr = insn_nr;
	  int j;
	  for (j = i + 1; j < XVECLEN (split, 0); j++)
	    if (GET_CODE (XVECEXP (split, 0, j)) == MATCH_DUP)
	      {
		if (XINT (XVECEXP (split, 0, j), 0) == XINT (elt, 0))
		  last_insn_nr = cur_insn_nr;
	      }
	    else if (GET_CODE (XVECEXP (split, 0, j)) != MATCH_SCRATCH)
	      cur_insn_nr++;

	  printf ("  if ((operands[%d] = peep2_find_free_register (%d, %d, \"%s\", %smode, &_regs_allocated)) == NULL_RTX)\n\
    return NULL;\n",
		  XINT (elt, 0),
		  insn_nr, last_insn_nr,
		  XSTR (elt, 1),
		  GET_MODE_NAME (GET_MODE (elt)));

	}
      else if (GET_CODE (elt) != MATCH_DUP)
	insn_nr++;
    }
}

int
main (int argc, char **argv)
{
  rtx desc;

  progname = "genemit";

  if (init_md_reader_args (argc, argv) != SUCCESS_EXIT_CODE)
    return (FATAL_EXIT_CODE);

  /* Assign sequential codes to all entries in the machine description
     in parallel with the tables in insn-output.c.  */

  insn_code_number = 0;
  insn_index_number = 0;

  printf ("/* Generated automatically by the program `genemit'\n\
from the machine description file `md'.  */\n\n");

  printf ("#include \"config.h\"\n");
  printf ("#include \"system.h\"\n");
  printf ("#include \"coretypes.h\"\n");
  printf ("#include \"tm.h\"\n");
  printf ("#include \"rtl.h\"\n");
  printf ("#include \"tm_p.h\"\n");
  printf ("#include \"function.h\"\n");
  printf ("#include \"expr.h\"\n");
  printf ("#include \"optabs.h\"\n");
  printf ("#include \"real.h\"\n");
  printf ("#include \"flags.h\"\n");
  printf ("#include \"output.h\"\n");
  printf ("#include \"insn-config.h\"\n");
  printf ("#include \"hard-reg-set.h\"\n");
  printf ("#include \"recog.h\"\n");
  printf ("#include \"resource.h\"\n");
  printf ("#include \"reload.h\"\n");
  printf ("#include \"toplev.h\"\n");
  printf ("#include \"tm-constrs.h\"\n");
  printf ("#include \"ggc.h\"\n\n");
  printf ("#include \"basic-block.h\"\n\n");
  printf ("#define FAIL return (end_sequence (), _val)\n");
  printf ("#define DONE return (_val = get_insns (), end_sequence (), _val)\n\n");

  /* Read the machine description.  */

  while (1)
    {
      int line_no;

      desc = read_md_rtx (&line_no, &insn_code_number);
      if (desc == NULL)
	break;

      switch (GET_CODE (desc))
	{
	case DEFINE_INSN:
	  gen_insn (desc, line_no);
	  break;

	case DEFINE_EXPAND:
	  printf ("/* %s:%d */\n", read_rtx_filename, line_no);
	  gen_expand (desc);
	  break;

	case DEFINE_SPLIT:
	  printf ("/* %s:%d */\n", read_rtx_filename, line_no);
	  gen_split (desc);
	  break;

	case DEFINE_PEEPHOLE2:
	  printf ("/* %s:%d */\n", read_rtx_filename, line_no);
	  gen_split (desc);
	  break;

	default:
	  break;
	}
      ++insn_index_number;
    }

  /* Write out the routines to add CLOBBERs to a pattern and say whether they
     clobber a hard reg.  */
  output_add_clobbers ();
  output_added_clobbers_hard_reg_p ();

  fflush (stdout);
  return (ferror (stdout) != 0 ? FATAL_EXIT_CODE : SUCCESS_EXIT_CODE);
}