/* Common subexpression elimination for GNU compiler.
   Copyright (C) 1987, 88, 89, 92-7, 1998, 1999 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.  */

/* Describe a value.  */
typedef struct cselib_val_struct
{
  /* The hash value.  */
  unsigned int value;
  union
  {
    /* A VALUE rtx that points back to this structure.  */
    rtx val_rtx;
    /* Used to keep a list of free cselib_val structures.  */
    struct cselib_val_struct *next_free;
  } u;

  /* All rtl expressions that hold this value at the current time during a
     scan.  */
  struct elt_loc_list *locs;
  /* If this value is used as an address, points to a list of values that
     use it as an address in a MEM.  */
  struct elt_list *addr_list;
} cselib_val;

/* A list of rtl expressions that hold the same value.  */
struct elt_loc_list
{
  /* Next element in the list.  */
  struct elt_loc_list *next;
  /* An rtl expression that holds the value.  */
  rtx loc;
  /* The insn that made the equivalence.  */
  rtx setting_insn;
};

/* A list of cselib_val structures.  */
struct elt_list
{
  struct elt_list *next;
  cselib_val *elt;
};

extern cselib_val *cselib_lookup	PARAMS ((rtx, enum machine_mode, int));
extern void cselib_update_varray_sizes	PARAMS ((void));
extern void cselib_init			PARAMS ((void));
extern void cselib_finish		PARAMS ((void));
extern void cselib_process_insn		PARAMS ((rtx));
extern int rtx_equal_for_cselib_p	PARAMS ((rtx, rtx));
extern int references_value_p		PARAMS ((rtx, int));