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.

*/

/* 	$Id: weights.c,v 1.1.1.1 1998/01/17 15:56:01 release Exp $	 */

#ifndef lint

static char vcid[] = "$Id: weights.c,v 1.1.1.1 1998/01/17 15:56:01 release Exp $";

#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 PROTO_S ((double scale, exp e));

weights add_weights

    PROTO_N ( ( w1,w2 ) )

    PROTO_T ( weights *w1 X 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

    PROTO_N ( ( loc, ws, fix ) )

    PROTO_T ( double loc X weights * ws X 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

    PROTO_N ( ( m,ws ) )

    PROTO_T ( double m X 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

    PROTO_N ( ( scale, re ) )

    PROTO_T ( double scale X 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

    PROTO_N ( ( scale, e ) )

    PROTO_T ( double scale X 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)));

     }

    }

}