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/*
                 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 15:56:05 $
$Revision: 1.1.1.1 $
$Log: code_here.c,v $
 * Revision 1.1.1.1  1998/01/17  15:56:05  release
 * First version to be checked into rolling release.
 *
 * Revision 1.2  1995/08/16  16:06:31  currie
 * Shortened some .h names
 *
 * Revision 1.1  1995/04/13  09:08:06  currie
 * Initial revision
 *
***********************************************************************/
/******************************************************************
                code_here

This contains procedures :-

regofval, fregofval : to see if an exp is a load_tag that has been allocated to a register.

regoperand, freoperand : to evaluate an exp into a register using make_code

code_here :  calls make_code and ensures that any internal exit labels are tied up after the call


        The procedures regoperand and fregoperand evaluate their
exp parameter into a single register using make_code. This register is
returned. An initial test with regofval checks to see if the exp is already
in a register.

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

#include "config.h"
#include "common_types.h"
#include "addrtypes.h"
#include "procrectypes.h"
#include "labels.h"
#include "expmacs.h"
#include "tags.h"
#include "new_code.h"
#include "exp.h"
#include "bitsmacs.h"
#include "locate.h"
#include "regexps.h"
#include "inst_fmt.h"
#include "mips_ins.h"
#include "shapemacs.h"
#include "special.h"
#include "handle_sregs.h"
#include "code_here.h"


/*********************************************************************
regofval
The procedure regofval checks to see if an exp is a load_tag
that has been allocated into a fixpnt register and if so return it or else 100.
*********************************************************************/
int   regofval
    PROTO_N ( (e) )
    PROTO_T ( exp e )
{
        exp decx = son (e);
  if (name (e) == name_tag && name (decx) == ident_tag) {/* ident tag */
    if ((props (decx) & defer_bit) != 0) {
      return regofval (son (decx));
    }
    if ((props (decx) & inreg_bits) != 0) {
      return ((isvar (decx)) ? (-no (decx)) : (no (decx)));
    }
    return 100;
  }
  else
  if ((name (e) == val_tag && no (e) == 0) ||
                 name(e) == clear_tag || name(e)== top_tag) {
        return 0;
  }
  else {
        return 100;
  }
}

int   fregofval
    PROTO_N ( (e) )
    PROTO_T ( exp e )
{
        exp decx = son (e);
  if (name (e) == name_tag && name (decx) == ident_tag) {
    if ((props (decx) & infreg_bits) != 0) {
      return no (decx);
    }
    return 100;
  }
  else
  if (name(e)==clear_tag || name(e)==top_tag) {
        return 0;
  }
  else {
      return 100;
  }
}

/**********************************************************************
code_here
The procedure code_here calls make_code and ensures that
any internal exit labels are tied up after the call.
**********************************************************************/

int   code_here
    PROTO_N ( (e, sp, dest) )
    PROTO_T ( exp e X space sp X where dest )
{
        makeans mka;
  mka = make_code (e, sp, dest, 0);
  if (mka.lab != 0) {
    set_label (mka.lab);
  }
  return mka.regmove;
}

ash ash0 = {
  0, 0
};
ash ash32 = {
  32, 32
};


int   reg_operand
    PROTO_N ( (e, sp) )
    PROTO_T ( exp e X space sp )
{
  int   x = regofval (e);
  ans aa;
  where w;
  if (x >= 0 && x < 100) {
    return x;
  }                             /* x is a register for e */
  if (name (e) == cont_tag) {
    x = regofval (son (e));
    if (x < 0) {
      return (-x);
    }
  }
  else
    if (name (e) == apply_tag && specialfn (son (e)) == 0) {
                                /* apply proc */
      setregalt (aa, 0);
      w.answhere = aa;
      w.ashwhere = ash0;
      make_code (e, sp, w, 0);
      return 2;                 /* simple proc calls give result in reg 2
                                */
    }

  aa = iskept (e);
  if (aa.discrim == inreg && regalt (aa) != 0) {
                                /* the same expression has already been
                                   evaluated into a reg */
    return regalt (aa);
  }
  if (aa.discrim == notinreg) {
    instore is;
    is = insalt (aa);
    if (is.adval && is.b.offset == 0) {
      int   r = is.b.base;
      /* the same expression has already been evaluated into a reg */
      return r;
    }
  }

  {
    int   reg = -1;
    setsomeregalt (aa, &reg);
    /* allow code_here to evaluate e into reg of its choice */
    w.answhere = aa;
    w.ashwhere = ashof (sh (e));
    code_here (e, sp, w);
    keepreg (e, reg);
    return reg;
  }
}

int   freg_operand
    PROTO_N ( (e, sp) )
    PROTO_T ( exp e X space sp )
{
  int   x = fregofval (e);
  ans aa;
  where w;
  freg fr;
  w.ashwhere = ashof (sh (e));
  if (x >= 0 && x < 100) {
    return x;
  }
  if (name (e) == cont_tag) {
    x = fregofval (son (e));
    if (x < 100) {
      return (x);
    }
  }
  else
    if (name (e) == apply_tag) {
      setregalt (aa, 0);
      w.answhere = aa;
      w.ashwhere = ash0;
      make_code (e, sp, w, 0);
      return 0;
    }

  aa = iskept (e);
  if (aa.discrim == infreg) {   /* e already evaluated in fl reg */
    return regalt (aa) /* cheat */ ;
  }

 { int reg = -1;
   somefreg sfr;
   sfr.fr = &reg;
   sfr.dble = fr.dble = (w.ashwhere.ashsize == 64) ? 1 : 0;
  setsomefregalt (aa, sfr);
  w.answhere = aa;
  /* evaluate e into reg ... */
  code_here (e, sp, w);
  fr.fr = reg;
  setfregalt(aa, fr);
  keepexp (e, aa);
  return reg;
 }
}