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/*

 * Copyright (c) 2002-2005 The TenDRA Project <http://www.tendra.org/>.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are met:

 *

 * 1. Redistributions of source code must retain the above copyright notice,

 *    this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright notice,

 *    this list of conditions and the following disclaimer in the documentation

 *    and/or other materials provided with the distribution.

 * 3. Neither the name of The TenDRA Project nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific, prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS

 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;

 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF

 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 *

 * $Id$

 */

/*

    		 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.

*/

/* 	$Id$	 */

#ifndef lint

static char vcid[] = "$Id$";

#endif /* lint */

/*

   weights.c

   The main procedure here is weightsv which determines the

   allocation of s regs. It considers which of those tags not

   already allocated to a t reg by scan, are best put in an s

   register. The same conditions as for t regs apply as to the

   suitability of the tags for registers.  Weights estimates the

   usage of each tag and hence the amount that would be saved if

   it were held in an s reg. Thus it computes break points for

   register allocation for later use by reg_alloc.  The type

   weights consists of two arrays of integers. In the first array

   each integer corresponds to a fixpnt reg and the second arrays'

   integers correspond to floating point regs.  At the end of a

   call of weights on an ident exp the props field of the ident

   may still contain inreg_bits or infreg_bits, set by scan, to

   indicate that a t reg should be used. Otherwise number of ident

   is set up to represent the break point for allocation. A similar

   process occurs for proc parameters which have the break value

   in the forweights field of the parapair of the corresponding

   procrec. This value has three meanings:

   1) The ident (or parameter) defines a fixpnt value and number

   of ident (forweights of parpair) is an integer brk with the

   interpretation that if there are at least brk fixpt s registers

   unallocated at this point then one will be used for this tag

   (parameter).

   2) As 1 but for floating point values.

   3) number of ident = 100 in which case allocate value on the

   stack, (this is obviously always available for parameters).

*/

/*

$Log: weights.c,v $

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

 * First version to be checked into rolling release.

 *

 * Revision 1.4  1996/02/19  09:25:40  john

 * Added assertion

 *

 * Revision 1.3  1995/06/13  14:04:03  john

 * Cosmetic change

 *

 * Revision 1.2  1995/05/16  10:56:50  john

 * Changes for spec 3.1

 *

 * Revision 1.1.1.1  1995/03/23  10:39:26  john

 * Entered into CVS

 *

 * Revision 1.4  1995/03/23  10:17:15  john

 * Added sequence to tested cases

 *

*/

#include "config.h"

#include <limits.h>

#include "common_types.h"

#include "exptypes.h"

#include "exp.h"

#include "expmacs.h"

#include "tags.h"

#include "procrectypes.h"

#include "procrecs.h"

#include "bitsmacs.h"

#include "maxminmacs.h"

#include "regable.h"

#include "shapemacs.h"

#include "special.h"

#include "weights.h"

weights zeroweights =

{{

    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

},

{

  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

}

};

weights weightsv(double scale, exp e);

weights add_weights

(weights *w1, weights *w2)

{

  /* sum of weights*/

  weights r;

  long  i;

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

   (r.fix)[i] = (w1->fix)[i] + (w2->fix)[i];

  };

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

   (r.floating)[i] = (w1->floating)[i] + (w2->floating)[i];

  };

  return(r);

}

/* loc is the usage count of a tag, ws is

   the weights computed for the scope of

   the tag and fix distinguishes between

   fix and float. This computes the

   weights for the declaration and a break

   point for register allocation which

   gives the number of available regs for

   which it is worthwhile to allocate this

   tag into a reg ("regged"). This proc is

   the source of all non-zero weights. NB

   loc may be negative since using a s-reg

   will involve a dump and restore  */

wp max_weights

(double loc, weights * ws, bool fix)

{

  long  bk = wfixno + 1;

  long  i;

  float *w = (ws -> fix);

  /*  w[i] = greatest usage of (i+1) inner fixed tags  */

  wp res;

  float *pw = & (((res.wp_weights).fix)[0]);

  if (fix) {

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

      if (i == 0) {

	if (loc > w[i]) {

	  /* this tag has higher usage than any inner one ... */

	  pw[i] = loc;

	  bk = i;		/* ... so it's regged in pref to others */

	}

	else

	  pw[i] = w[i];

      }

      else {

	if ((loc + w[i - 1]) > w[i]) {

	  /* this tag and i inner ones have higher usage than any other

	     (i+1) inner ones ... */

	  pw[i] = loc + w[i - 1];

	  if (i < bk)

	    bk = i;

	  /* ... so it and i inner ones are regged in preference to any

	     other (i+1) inner ones */

	}

	else

	  pw[i] = w[i];

      };

    };

    res.fix_break = bk;

  }

  else {

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

      pw[i] = w[i];

    }

  }

  res.fix_break = bk;

  bk = wfloatno + 1;

  w = (ws -> floating);

  pw = & (((res.wp_weights).floating)[0]);

  if (!fix) {			/* same algorithm for float regs as fixed

				   regs */

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

      if (i == 0) {

	if (loc > w[i]) {

	  pw[i] = loc;

	  bk = i;

	}

	else

	  pw[i] = w[i];

      }

      else {

	if ((loc + w[i - 1]) > w[i]) {

	  pw[i] = loc + w[i - 1];

	  if (i < bk)

	    bk = i;

	}

	else

	  pw[i] = w[i];

      };

    };

  }

  else {

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

      pw[i] = w[i];

    }

  }

  res.float_break = bk;

  return res;

}

weights mult_weights

(double m, weights *ws)

{

  /* multiply weights by scalar - non

     overflowing */

  weights res;

  float *r = & (res.fix)[0];

  float *w = ws -> fix;

  long  i;

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

      r[i] = w[i]* m;

  };

  r = & (res.floating)[0];

  w = ws -> floating;

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

      r[i] = w[i]* m;

  };

  return(res);

}

weights add_wlist

(double scale, exp re)

{

  weights w, w1;

  exp r = re;

  if (r == nilexp) {

    return zeroweights;

  }

  else

    if (last(r)) {

      return(weightsv(scale, r));

    }

    else {

      w = weightsv(scale, r);

      Assert(r != bro(r));

      do {

	r = bro(r);

	w1 = weightsv(scale, r);

	w = add_weights(&w, &w1);

      } while (!last(r));

      return w;

    }

}

/*

   weightsv

   This procedure estimates the usage of tags and parameters to

   help determine whether they can advantageously be placed in

   s registers.  The parameter scale allows more importance to

   be placed on usage inside 'for' loops for example. The

   procedure reg_alloc in reg_alloc.c finally determines the

   actual choice of s reg and recodes the number field of an ident.

*/

weights weightsv

(double scale, exp e)

{

 unsigned char  n;

 tailrecurse:

  n = name(e);

  switch (n) {

    case name_tag:

      {

	exp s = son(e);

	if (name(s) == ident_tag && !isglob(s)) {

	  if (is_floating(name(sh(e))) && name(sh(e))!= shrealhd) {

	  	fno(s) += scale*2.0;

	  } else fno(s) += scale;

	}

	/* usage of tag stored in number of son of load_name (decl) */

	return zeroweights;

      }

    case ident_tag:

      {

	if (son(e)!= nilexp) {

	  weights wdef;

	  weights wbody;

	  long  noe = no (e) /* set by scan */ ;

	  if ((name(son(e)) == clear_tag) || (props(e) & defer_bit)) {

	    wdef = zeroweights;

	    fno(e) = 0.0;

	  }

	  else {

	    /* maybe needs a store to initialise */

	    if (is_floating(name(sh(son(e)))) && name(sh(son(e)))!= shrealhd) {

	  		fno(e) = scale*2.0;

	    } else fno(e) = scale;

	    wdef = weightsv(scale, son(e));

	  }

	  /* weights for initialisation of dec */

	  wbody = weightsv(scale, bro(son(e)));

	  /* weights of body of scan */

	  if (props (e) & defer_bit) {/* declaration will be treated

				   transparently in code production */

	    exp t = son(e);

	    exp s;

	    if (name(t) == val_tag || name(t) == real_tag) {

	      return wbody;

	    }

	    while (name(t)!= name_tag) {

	      t = son(t);

	    }

	    s = son(t);

	    if (name(s) == ident_tag && !isglob(t)) {

	      fno (s) = fno (e);	/* is this correct */

	    }

	    /* usage of tag stored in number of son of

	     load_name (decl) */

	    return wbody;

	  }			/* end deferred */

	  if ((props(e) & inreg_bits) == 0 && fixregable(e)) {

	    wp p;

	    p = max_weights(fno(e) - 2.0*scale , &wbody, 1);

	    /* usage decreased by 2 because of dump and

	       restore of s-reg

	    */

	    no(e) = p.fix_break;

	    return(add_weights(&wdef, &p.wp_weights));

	  }

	  else if ((props(e) & infreg_bits) == 0 && floatregable(e)) {

	    wp p;

	    p = max_weights(fno(e) - 2 * scale, &wbody, 0);

	    /* usage decreased by 4(on mips) because of dump

	       and restore of double s-reg */

	    no(e) = p.float_break;

	    return(add_weights(&wdef, &p.wp_weights));

	  }

	  else {

	    no (e) = noe /* restore to value given by scan */ ;

	    return add_weights(&wdef, &wbody);

	  }

	}

	else

	  return zeroweights;

      };

    case rep_tag: {

	e = bro(son(e));

	goto tailrecurse;

      }

    case case_tag: {

	e = son(e);

	goto tailrecurse;

      };

    case labst_tag: {

      scale = fno(e);

      e = bro(son(e));

      goto tailrecurse;

    }

    case val_tag:{

	return zeroweights;

      };

    case ncopies_tag: {

    	scale = no(e)*scale;

    	e = son(e);

    	goto tailrecurse;

    }

    case seq_tag: {

      exp l = son(son(e));

      exp r = bro(son(e));

      weights w,w1;

      w = weightsv(scale,l);

      while (!last(l)) {

	l = bro(l);

	w1 = weightsv(scale,l);

	w = add_weights(&w,&w1);

      }

      w1 = weightsv(scale,r);

      w = add_weights(&w,&w1);

      return w;

    }

     default: {

       if (son(e) == nilexp || n == env_offset_tag ||

	   n == general_env_offset_tag) {

	 return zeroweights;

	}

       if (last(son(e))) {

	 e = son(e);

	 goto tailrecurse;

       }

       return(add_wlist(scale, son(e)));

     }

    }

}