/* Read machine descriptions, return top level rtx for use by the
   various generation passes. 

   Copyright (C) 2000 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, 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "hconfig.h"
#include "system.h"
#include "rtl.h"
#include "errors.h"
#include "gensupport.h"

static FILE *input_file;

static int sequence_num;

struct queue_elem {
    rtx data;
    struct queue_elem *next;
};

static struct queue_elem *rtx_ready_queue;

/* Recursively remove constraints from an rtx.  */

static void
remove_constraints (part)
     rtx part;
{
  register int i, j;
  register const char *format_ptr;

  if (part == 0)
    return;

  if (GET_CODE (part) == MATCH_OPERAND)
    XSTR (part, 2) = "";
  else if (GET_CODE (part) == MATCH_SCRATCH)
    XSTR (part, 1) = "";

  format_ptr = GET_RTX_FORMAT (GET_CODE (part));

  for (i = 0; i < GET_RTX_LENGTH (GET_CODE (part)); i++)
    switch (*format_ptr++)
      {
      case 'e':
      case 'u':
	remove_constraints (XEXP (part, i));
	break;
      case 'E':
	if (XVEC (part, i) != NULL)
	  for (j = 0; j < XVECLEN (part, i); j++)
	    remove_constraints (XVECEXP (part, i, j));
	break;
      }
}

/* Handle any synthetic top level rtx, i.e. anything except:
       DEFINE_INSN
       DEFINE_EXPAND
       DEFINE_SPLIT
       DEFINE_PEEPHOLE
       DEFINE_PEEPHOLE2
       DEFINE_ATTRIBUTE
       DEFINE_FUNCTION_UNIT
       DEFINE_ASM_ATTRIBUTES */

static void
process_rtx (desc)
    rtx* desc;
{
  if (GET_CODE (*desc) == DEFINE_INSN_AND_SPLIT) 
    {
      struct queue_elem* elem = xmalloc (sizeof (struct queue_elem));
      const char *split_cond;
  
      /* Create a split with values from the insn_and_split. */
      rtx split = rtx_alloc (DEFINE_SPLIT);
      XEXP (split, 0) = copy_rtx (XEXP (*desc, 1));
      remove_constraints (XEXP (split, 0));
      split_cond = XSTR (split, 1) = XSTR (*desc, 4);
  
      /* If the split condition starts with "&&", append it to the
         insn condition to create the new split condition.  */
      if (split_cond[0] == '&' && split_cond[1] == '&')
        {
	const char *insn_cond = XSTR (*desc, 2);
  	char *combined = 
  	    xmalloc (strlen (insn_cond) + strlen (split_cond) + 1);
  	strcpy (combined, insn_cond);
  	strcat (combined, split_cond);
  	XSTR (split, 1) = combined;
        }
  
      XVEC (split, 2) = XVEC (*desc, 5);
      XSTR (split, 3) = XSTR (*desc, 6);
  
      /* Fix up the DEFINE_INSN.  */
      PUT_CODE (*desc, DEFINE_INSN);
      XVEC (*desc, 4) = XVEC (*desc, 7);
  
      /* Return the DEFINE_INSN part, and put the DEFINE_SPLIT
         in the queue.  */
      elem->next = rtx_ready_queue;
      elem->data = split;	
      rtx_ready_queue = elem;  
    }
}

/* The entry point for initializing the reader.  */

int 
init_md_reader (filename)
    const char *filename;
{

  input_file = fopen (filename, "r");

  if (input_file == 0)
    {
      perror (filename);
      return FATAL_EXIT_CODE;
    }

  read_rtx_filename = filename;
  sequence_num = 0;
  rtx_ready_queue = NULL; 

  return SUCCESS_EXIT_CODE;
}


/* The entry point for reading a single rtx from an md file.  */

rtx 
read_md_rtx (lineno, seqnr)
    int *lineno;
    int *seqnr;
{ 
  rtx desc;

  if (rtx_ready_queue != NULL) 
    {
      desc = rtx_ready_queue->data;
      rtx_ready_queue = rtx_ready_queue->next;
    }
  else 
    {
      int c;
      c = read_skip_spaces (input_file);
      if (c == EOF)
	return NULL;

      ungetc (c, input_file);
      desc = read_rtx (input_file);
      process_rtx (&desc);
    }
  *lineno = read_rtx_lineno;
  *seqnr = sequence_num;
  switch (GET_CODE (desc))
    {
      case DEFINE_INSN:
      case DEFINE_EXPAND:
      case DEFINE_SPLIT:
      case DEFINE_PEEPHOLE:
      case DEFINE_PEEPHOLE2:
	sequence_num++;
	break;

      default:
	break;
    }

  return desc;
}