Subversion Repositories tendra.SVN

/*

    		 Crown Copyright (c) 1997

    This TenDRA(r) Computer Program is subject to Copyright

    owned by the United Kingdom Secretary of State for Defence

    acting through the Defence Evaluation and Research Agency

    (DERA).  It is made available to Recipients with a

    royalty-free licence for its use, reproduction, transfer

    to other parties and amendment for any purpose not excluding

    product development provided that any such use et cetera

    shall be deemed to be acceptance of the following conditions:-

        (1) Its Recipients shall ensure that this Notice is

        reproduced upon any copies or amended versions of it;

        (2) Any amended version of it shall be clearly marked to

        show both the nature of and the organisation responsible

        for the relevant amendment or amendments;

        (3) Its onward transfer from a recipient to another

        party shall be deemed to be that party's acceptance of

        these conditions;

        (4) DERA gives no warranty or assurance as to its

        quality or suitability for any purpose and DERA accepts

        no liability whatsoever in relation to any use to which

        it may be put.

*/

/**********************************************************************

$Author: release $

$Date: 1998/01/17 15:56:06 $

$Revision: 1.1.1.1 $

$Log: regexps.c,v $

 * Revision 1.1.1.1  1998/01/17  15:56:06  release

 * First version to be checked into rolling release.

 *

 * Revision 1.7  1996/01/25  17:07:21  currie

 * Alias with bit-fields

 *

 * Revision 1.6  1996/01/08  17:05:33  currie

 * current_env in depends_on

 *

 * Revision 1.5  1995/10/20  10:48:03  currie

 * avs -slow + attempts to cheat buggy scheduler

 *

 * Revision 1.4  1995/09/12  10:59:41  currie

 * gcc pedanttry

 *

 * Revision 1.3  1995/09/04  10:11:57  currie

 * e changes !

 *

 * Revision 1.2  1995/08/16  16:07:08  currie

 * Shortened some .h names

 *

 * Revision 1.1  1995/04/13  09:08:06  currie

 * Initial revision

 *

***********************************************************************/

/* regexps.c

For trivial 'peephole' optimisations

*/

#include "config.h"

#include "expmacs.h"

#include "addrtypes.h"

#include "tags.h"

#include "move.h"

#include "bitsmacs.h"

#include "maxminmacs.h"

#include "shapemacs.h"

#include "common_types.h"

#include "extratags.h"

#include "check.h"

#include "basicread.h"

#include "regexps.h"

regpeep regexps[48];		/* [0:31] fix pt - [32:47] floating pt */

bool sim_exp PROTO_S ((exp a, exp b));

bool eq_sze

    PROTO_N ( (as, bs) )

    PROTO_T ( shape as X shape bs )

{

  if (is_floating(name(as))) return(name(as)==name(bs));

  if (is_floating(name(bs))) return 0;

  return (shape_size(as) == shape_size(bs) && shape_align(as)==shape_align(bs));

}

bool sim_explist

    PROTO_N ( (al, bl) )

    PROTO_T ( exp al X exp bl )

{

  if (al == nilexp && bl == nilexp)

    return (1);

  if (al == nilexp || bl == nilexp)

    return (0);

  if (!sim_exp (al, bl))

    return (0);

  if (last (al) && last (bl))

    return (1);

  if (last (al) || last (bl))

    return (0);

  return (sim_explist (bro (al), bro (bl)));

}

bool sim_exp

    PROTO_N ( (a,b) )

    PROTO_T ( exp a X exp b )

{	/* basically eq_exp except equal shapes

				   requirement  is weakened to equal sizes

				   and alignments */

  if (name (a) == name (b)) {

    if (name (a) == name_tag)

      return (son (a) == son (b) && no (a) == no (b) &&

	  eq_sze (sh (a), sh (b)));

    if (name(a)==maxlike_tag || name(a)==minlike_tag || name(a)==abslike_tag) {

    	return (props(son(a))==props(son(b)) &&

		shape_size(sh(a))==shape_size(sh(b)) &&

    			sim_explist(son(son(a)),son(son(b)) ) );

    }

    if (!is_a (name (a)) || !eq_sze (sh (a), sh (b)))

      return (0);

    if (name(a) == float_tag) return eq_exp(son(a), son(b));

    return (no (a) == no (b) &&

	sim_explist (son (a), son (b)));

  };

  return (0);

}

void clear_all

    PROTO_Z ()

{	/* forget all register - exp associations */

  int   i;

  for (i = 0; i < 48; i++) {

    regexps[i].keptexp = nilexp;

    setregalt (regexps[i].inans, 0);

  }

}

void clear_reg

    PROTO_N ( (i) )

    PROTO_T ( int i )

{	/* forget reg i - exp association */

  i = abs (i);

  if (i >= 0 && i < 48) {

    regexps[i].keptexp = nilexp;

    setregalt (regexps[i].inans, 0);

  }

}

ans iskept

    PROTO_N ( (e) )

    PROTO_T ( exp e )

{		/* find if e has already been evaluated

				   into a register */

  int   i;

  ans nilans;

  ans aa;

  setregalt (nilans, 0);

  aa = nilans;

  for (i = 0; i < 48; i++) {

    exp ke = regexps[i].keptexp;

    bool isc = regexps[i].iscont;

    if (ke != nilexp) {		/* there is an accociation with reg i */

      if (

	  ((!isc && sim_exp (ke, e)) ||

	    (name (e) == cont_tag && isc  &&

	      eq_sze (sh (ke), sh (e))

	      && sim_exp (ke, son (e))  && al1(sh(son(e))) == al1(sh(ke)) )

	  )

	) {

	aa = (regexps[i].inans);

	switch (aa.discrim) {

	  case notinreg:

	    {

	      if (!aa.val.instoreans.adval) {

				/* the expression is given indirectly - it

				   may have also been loaded into a

				   register */

		continue;

	      }

	      /* else ... */

	    }

	  default:

	    return aa;

	}

      }

      else

	if (name (ke) == cont_tag && !isc) {

	  ans aq;

	  aq = regexps[i].inans;

	  if (aq.discrim == notinreg) {

	    instore is;

	    is = insalt (aq);

	    if (!is.adval && is.b.offset == 0 && is.b.base > 0 && is.b.base < 31

		&& sim_exp (son (ke), e)) {

				/* the contents of req expression is here

				   as a reg-offset */

	      is.adval = 1;

	      setinsalt (aq, is);

	      return aq;

	    }

	  }

	}

	else

	  if (name (ke) == reff_tag && !isc) {

	    ans aq;

	    aq = regexps[i].inans;

	    if (aq.discrim == notinreg) {

	      instore is;

	      is = insalt (aq);

	      if (is.adval && is.b.offset == (no (ke) / 8)

		  && is.b.base > 0 && is.b.base < 31

		  && sim_exp (son (ke), e)) {

				/* a ref select of req expression is here

				   as a reg-offset */

		is.adval = 1;

		is.b.offset = 0;

		setinsalt (aq, is);

		return aq;

	      }

	    }

	  }

    }

  }

  return aa;

}

void keepexp

    PROTO_N ( (e, loc) )

    PROTO_T ( exp e X ans loc )

{	/* set up exp - address association */

  int   pos;

  switch (loc.discrim) {

    case insomereg:

    case insomefreg: {

	failer ("Keep ? reg");

      }

    case inreg:

      {

	pos = regalt (loc);

	break;

      }

    case infreg:

      {

	pos = fregalt (loc).fr + 32;

	break;

      }

    case notinreg:

      {

	pos = insalt (loc).b.base;

	if (pos < 0 || pos > 30)

	  return;

      }

  };

  if (pos==2 || pos == 32) return;

  regexps[pos].keptexp = e;

  regexps[pos].inans = loc;

  regexps[pos].iscont = 0;

}

void keepcont

    PROTO_N ( (e, reg) )

    PROTO_T ( exp e X int reg )

{/* set up cont(e)-reg association */

  freg fr;

  int   z = abs (reg);

  if (z==2|| z==32) return;

  if (z > 31) {

    fr.dble = (reg < 0);

    fr.fr = z - 32;

    setfregalt (regexps[z].inans, fr);

  }

  else {

    instore is;

    is.b.base = reg;

    is.b.offset = 0;

    is.adval = 1;

    setinsalt (regexps[z].inans, is);

  }

  regexps[z].keptexp = e;

  regexps[z].iscont = 1;

}

void keepreg

    PROTO_N ( (e, reg) )

    PROTO_T ( exp e X int reg )

{	/* set up e-reg association */

  freg fr;

  int   z = abs (reg);

  if (z==2 || z==32) return;

  if (z > 31) {

    fr.dble = (reg < 0);

    fr.fr = z - 32;

    setfregalt (regexps[z].inans, fr);

  }

  else {

    instore is;

    is.b.base = reg;

    is.b.offset = 0;

    is.adval = 1;

    setinsalt (regexps[z].inans, is);

  }

  regexps[z].keptexp = e;

  regexps[z].iscont = 0;

}

static bool couldeffect PROTO_S ((exp e, exp z, int count));

static bool couldbe

    PROTO_N ( (e, lhs, count) )

    PROTO_T ( exp e X exp lhs X int count )

{ /* could e be lhs? */

  int   ne = name (e);

  exp s = son (e);

  if (ne == name_tag) {

    if (lhs != 0 && s == son (lhs)) {

	return 1;

    }

    if (isvar (s)) {

      return (lhs == 0 && (isvis (s) || isglob(s)));

    }

    if (name (s) == proc_tag)

      return (lhs == 0);

    if (son (s) == nilexp)

      return 1;

    if (count > 5) return 1; /* pathological */

    return couldbe (son (s), lhs, count+1);

  }

  if (ne == cont_tag) {

    if (lhs != 0 && name (s) == name_tag && son (s) != nilexp) {

      return (son (s) == son (lhs) || isvis (son (lhs)) || isvis (son (s)));

    }

    return 1;

  }

  if (ne == reff_tag || ne == field_tag) {

    return couldbe (s, lhs, count);

  }

  if (ne == addptr_tag || ne == subptr_tag) {

    return (couldbe (s, lhs, count) || couldeffect (bro (s), lhs, count));

  }

  return 1;

}

static bool couldeffect

    PROTO_N ( (e, z, count) )

    PROTO_T ( exp e X exp z X int count )

{

				/* could alteration to z effect e? */

  int   ne = name (e);

  if (ne == cont_tag) {

    return couldbe (son (e), z, count);

  }

  if (ne == name_tag) {

    if (isvar (son (e)))

      return (z == 0 && isvis (son (e)));

    if (name (son (e)) == proc_tag)

      return 0;

    if (son (son (e)) == nilexp)

      return 1 /* could it happen? */ ;

    if (count > 5) return 1; /* pathological */

    return couldeffect (son (son (e)), z, count+1);

  }

  if (ne < plus_tag || ne == contvol_tag)

    return 1;

  e = son (e);

  while (e != nilexp) {

    if (couldeffect (e, z, count))

      return 1;

    if (last (e))

      return 0;

    e = bro (e);

  }

  return 0;

}

bool dependson

    PROTO_N ( (e, isc, z) )

    PROTO_T ( exp e X bool isc X exp z )

{/* does e depend on z */

  if (e == nilexp) {

    return 0;

  }

  for (;;) {

    if (name (z) == reff_tag || name (z) == addptr_tag ||

	name (z) == subptr_tag) {

      z = son (z);

    }

   if (name (z) != name_tag) {

    if (name (z) != cont_tag)

      return 1;

    z = 0;

    break;

   }

    if (isvar (son (z)))

      break;

    if (name (son (z)) == proc_tag) {

      z = 0;

      break;

    }

    if (son (son (z)) == nilexp)

      return 1;			/* can it happen? */

    z = son (son (z));

  }

  /* z is now unambiguous variable name or 0 meaning some contents */

  return ((isc) ? couldbe (e, z, 0) : couldeffect (e, z, 0));

}

void clear_dep_reg

    PROTO_N ( (lhs) )

    PROTO_T ( exp lhs )

{	/* remove association of any register

				   which depends on lhs */

  int   i;

  for (i = 0; i < 48; i++) {

    if (dependson (regexps[i].keptexp, regexps[i].iscont, lhs)) {

      regexps[i].keptexp = nilexp;

      setregalt (regexps[i].inans, 0);

    }

  }

}