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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

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

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 * 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.

*/

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

$Author: release $

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

$Revision: 1.1.1.1 $

$Log: locate.c,v $

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

 * First version to be checked into rolling release.

 *

 * Revision 1.3  1995/09/12  10:59:30  currie

 * gcc pedanttry

 *

 * Revision 1.2  1995/08/16  16:06:50  currie

 * Shortened some .h names

 *

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

 * Initial revision

 *

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

/* locate.c

     discovers "where" an "exp" is;

     The where coding of an address tells one whether the result of

      evaluating an exp is in a register or directly or literally in store,

*/

#include "config.h"

#include "addrtypes.h"

#include "expmacs.h"

#include "tags.h"

#include "inst_fmt.h"

#include "mips_ins.h"

#include "bitsmacs.h"

#include "exp.h"

#include "procrectypes.h"

#include "guard.h"

#include "eval.h"

#include "regexps.h"

#include "shapemacs.h"

#include "psu_ops.h"

#include "getregs.h"

#include "move.h"

#include "handle_sregs.h"

#include "common_types.h"

#include "frames.h"

#include "code_here.h"

#include "locate.h"

#include "basicread.h"

extern  FILE * as_file;

long  locals_offset;		/* the offset in bits of start of current

				   locals */

long  frame_size;		/* the size of the current stack frame in

				   bits */

baseoff boff

(exp id)

{		/* decodes id to give a baseoff suitable

				   for ls_ins etc */

  baseoff an;

  if (isglob (id)) {		/* globals */

    dec * gl = brog(id);

    long sno = gl->dec_u.dec_val.sym_number;

    an.base = - (sno + 1);

    an.offset = 0;

  }

  else {

    int   x = no(id);

    int   b = x & 0x3f;

    if (name(son(id)) ==caller_name_tag) {

    	an.base = 29;

    	an.offset = (x-b) >>4;

    	/* caller tags */

    }

    else

    if (b == 29) {

      an.base = 29;

      an.offset = ((x - b) >> 4) + (locals_offset >> 3);

      /* locally declared things accessed by sp*/

    }

    else

    if ((b==30 && Has_fp)) {

      an.base = b;

      an.offset = (((x - b)) >> 4) + (locals_offset >> 3)

      			- ((frame_size+callee_size) >>3);

      /* locally declared things accessed by fp  */

    }

    else

    if ((b == local_reg && Has_vcallees)) {

      an.base = b;

      an.offset = (((x - b)) >> 4) + (locals_offset >> 3)

      			- (frame_size>>3);

      /* locally declared things accessed by local_reg */

    }

    else

      if (b <= 31) {

	an.base = b;

	an.offset = ((x - b) >> 4);

	/* other base offsets */

      }

      else

	if (b == 32) {

	  an.base = - ((x - b) >> 6);

	  an.offset = 0;

	  /* global names  */

	}

	else

	  if (b == 33) {

	    an.base = (x - b) >> 6;

	    an.offset = 0;

	    /* global anonymous */

	  }

	  else {

	    failer("not a baseoff in boff ");

	  }

  }

  return an;

}

where locate(exp e, space sp, shape s, int dreg);

 /* locate differs from locate1 only in that it looks to see e has already

    been evaluated somehow */

where locate1

(exp e, space sp, shape s, int dreg)

{

				/* finds the address of e using shape s;

				   sp gives available t-regs for any inner

				   evaluation. dreg is historical. */

  ash a;

  ans aa;

  where wans;

  a = ashof(s);

/*  while (name (e) == diag_tag || name (e) == fscope_tag

      || name (e) == cscope_tag) {

    e = son (e);

  }

*/

  switch (name(e)) {

    case name_tag:

      {

	exp decx = son(e);

	bool var = isvar(decx);

				/* this a locally declared name ... */

	  if (props(decx) & defer_bit) {

				/* ... it has been identified with a

				   simple expression which is better

				   evaluated every time */

	    where w;

	    w = locate(son(decx), sp, sh(son(decx)), dreg);

	    if (no(e) == 0) {

	      aa = w.answhere;

	    }

	    else {

	      instore is;

	      switch (w.answhere.discrim) {

		case notinreg:

		  {

		    is = insalt(w.answhere);

		    is.b.offset += (no(e) / 8);

		    break;

		  }

		default:

		  failer("NOT deferable");

	      }

	      setinsalt(aa, is);

	    }

	  }

	  else

	    if (props(decx) & inreg_bits) {

				/* ... it has been allocated in a fixed

				   point reg */

	      if (var) {

		setregalt(aa, no(decx));

	      }

	      else {

		instore b;

		b.b.base = no(decx);

		b.b.offset = 0;

		b.adval = 1;

		setinsalt(aa, b);

	      }

	    }

	    else

	      if (props(decx) & infreg_bits) {

				/* ... it has been allocated in a floating

				   point reg */

		freg fr;

		fr.fr = no(decx);

		fr.dble = (a.ashsize == 64)? 1 : 0;

		setfregalt(aa, fr);

	      }

	      else {		/* ... it is in memory */

		instore is;

		if (var || (name(sh(e)) == prokhd &&

		     (son(decx) == nilexp || name(son(decx)) == proc_tag

	                || name(son(decx)) == general_proc_tag))) {

		  is.adval = 1;

		}

		else {

		  is.adval = 0;

		}

		is.b = boff(decx);

		is.b.offset += (no(e) / 8);

		setinsalt(aa, is);

	      }

	wans.answhere = aa;

	wans.ashwhere = a;

	return wans;

      }

    case addptr_tag:

      {

	exp sum = son(e);

	where wsum;

	int   addend;

	space nsp;

	int   reg;

	int   ind;

	instore is;

	ans asum;

	wsum = locate(sum, sp, sh(sum), 0);

	asum = wsum.answhere;

	/* answer is going to be wsum displaced by integer result of

	   evaluating bro(sum) */

	switch (asum.discrim) {

	  case notinreg:

	    {

	      is = insalt(asum);

	      if (is.adval) {	/* wsum is a literal address in store ...

				*/

		baseoff b;

		b = is.b;

		if (b.base < 0 || b.base > 31) {

				/* ... it is not a base-offset , so make

				   it one */

		  reg = getreg(sp.fixed);

		  ls_ins(i_la, reg, b);

		  keepreg(sum, reg);

		  b.base = reg;

		  b.offset = 0;

		}

		nsp = guardreg(b.base, sp);

		addend = reg_operand(bro(sum), nsp);

		/* evaluate the displacement ... */

		if (dreg == 0)

		  dreg = getreg(nsp.fixed);

		rrr_ins(i_addu, dreg, b.base, addend);

		/* ... add it to the base register into new reg */

		b.base = dreg;

		is.b = b;

		setinsalt(aa, is);

		wans.answhere = aa;

		wans.ashwhere = a;

		/* ...and use it as base a literal base-offset result */

		keepexp(e, aa);

		return wans;

	      }

	      else {		/* wsum represents an actual pointer in

				   store... */

		ind = getreg(sp.fixed);

		ls_ins(i_lw, ind, is.b);

		/* ... so load it into a good register */

	      }

	      goto breakpt;

	      /* should be break - thought there was cc error */

	    }			/* end notinreg */

	  case inreg:

	    /* wsum is already in reg */

	    {

	      ind = regalt(asum);

	      goto breakpt;

	    }

	  default: {

	      failer("Locate ? reg");

	    }

	}			/* end case */

    breakpt: 			/* register ind contains the evaluation of

				   1st operand of addptr */

	nsp = guardreg(ind, sp);

	if (name(bro(sum)) == env_offset_tag

		|| name(bro(sum)) == general_env_offset_tag) {

          is.b.base = ind;

          is.b.offset = frame_offset(son(bro(sum)));

	}

	else {

          addend = reg_operand(bro(sum), nsp);

          /* evaluate displacement .... */

          if (dreg == 0)

            dreg = getreg(nsp.fixed);

          rrr_ins(i_addu, dreg, ind, addend);

          /* ... add it to ind in new reg */

          is.b.base = dreg;

          is.b.offset = 0;

        }

	is.adval = 1;

	setinsalt(aa, is);

	wans.answhere = aa;

	wans.ashwhere = a;

	/* ... and deliver literal base_offset */

	keepexp(e, aa);

	return wans;

      }				/* end add_ptr */

    case subptr_tag: 		/* this is nugatory - previous transforms

				   make it into addptr or reff */

      {

	exp sum = son(e);

	int   ind = reg_operand(sum, sp);

	instore isa;

	isa.adval = 1;

	sum = bro(sum);

	if (name(sum) == val_tag) {

	  instore isa;

	  isa.b.base = ind;

	  isa.b.offset = -no(e);

	  setinsalt(aa, isa);

	}

	else {

	  if (dreg == 0)

	    dreg = getreg(sp.fixed);

	  rrr_ins(i_subu, dreg, ind,

	      reg_operand(sum, guardreg(ind, sp)));

	  isa.b.base = dreg;

	  isa.b.offset = 0;

	}

	setinsalt(aa, isa);

	wans.answhere = aa;

	wans.ashwhere = a;

	keepexp(e, aa);

	return wans;

      }				/* end subptr */

    case reff_tag: {

	instore isa;

	wans = locate(son(e), sp, sh(son(e)), 0);

	/* answer is going to be wans displaced by no(e) */

	switch (wans.answhere.discrim) {

	  case notinreg: {

	      isa = insalt(wans.answhere);

	      if (!isa.adval) {

		/* wans is an actual pointer  in store, so make it into a

		   literal address.... */

		int   reg = getreg(sp.fixed);

		ls_ins(i_lw, reg, isa.b);

		isa.b.offset = 0;

		isa.b.base = reg;

		isa.adval = 1;

	      }

	      /* ... and add appropriate displacement to give result */

	      isa.b.offset += no(e) / 8;

	      setinsalt(wans.answhere, isa);

	      keepexp(e, wans.answhere);

	      break;

	    }

	  case inreg: {

	      /* wans is a pointer in a register */

	      isa.b.base = regalt(wans.answhere);

	      isa.adval = 1;

	      isa.b.offset = no(e) / 8;

	      setinsalt(wans.answhere, isa);

	      break;

	    }

	  default: {

	      failer("Locate ? reg ");

	    }

	}

	wans.ashwhere = a;

	return wans;

      }				/* end reff */

    case cont_tag:

    case contvol_tag:

      {

	exp s = son(e);

	ans ason;

	instore isa;

	int   reg;

	where fc;

	fc = locate(s, sp, sh(e), 0);

	ason = fc.answhere;

	/* answer is going to be the contents of address represented by fc

	   */

	switch (ason.discrim) {

	  case notinreg:

	    {

	      isa = insalt(ason);

	      if (isa.adval) {	/* fc is a literal store address, so make

				   it into a direct one */

		isa.adval = 0;

		setinsalt(aa, isa);

	      }

	      else {		/* fc is an actual pointer in store ....

				*/

		reg = getreg(sp.fixed);

		ls_ins(i_lw, reg, isa.b);

		/* .... so load it into reg and deliver direct base-offset

		   (reg,0) */

		isa.b.base = reg;

		isa.b.offset = 0;

		setinsalt(aa, isa);

		if (name(e)!= contvol_tag && fc.ashwhere.ashalign != 1)

		  keepexp(e, aa);

	      }

	      goto breakson;

	    }			/* end notinrg */

	  case inreg:

	    /* this one is fraught - it depends on only being used in

	       lh-value positions from vars- take care */

	    {

	      isa.b.base = regalt(ason);

	      isa.b.offset = 0;

	      isa.adval = 1;

	      setinsalt(aa, isa);

	      /* fc is in register, so deliver literal(!? ) base-offset */

	      goto breakson;

	    }

	  case infreg: 		/* ditto caveat above */

	    {

	      aa = ason;

	      goto breakson;

	    }

	  default: {

	      failer("Locate ? reg");

	    }

	}

    breakson:

	wans.answhere = aa;

	wans.ashwhere = a;

	return wans;

      }				/* end cont */

    case top_tag: 		/* does this ever happen ? */

      {

	setregalt(aa, 0);

	wans.answhere = aa;

	wans.ashwhere = a;

	return wans;

      }				/* end top */

    case field_tag: {

	instore isa;

	wans = locate(son(e), sp, sh(son(e)), 0);

	/* answer is wans displace literally by no(e); it should always be

	   a literal store adress */

	switch (wans.answhere.discrim) {

	  case notinreg: {

	      isa = insalt(wans.answhere);

	      isa.b.offset += no(e) / 8;

	      setinsalt(wans.answhere, isa);

	      break;

	    }

	  default:

	    failer(" field should be transformed ");

	}

	wans.ashwhere = a;

	return wans;

      }				/* end field */

    default:

      /* general catch all; evaluate e into register and deliver it as a

         literal store address */

      {

	int   r = reg_operand(e, sp);

	instore is;

	if (r == 2) {		/* guard possible result from proc - can

				   do better */

	  r = getreg(sp.fixed);

	  mon_ins(i_move, r, 2);

	}

	is.b.base = r;

	is.b.offset = 0;

	is.adval = 1;

	setinsalt(aa, is);

	wans.answhere = aa;

	wans.ashwhere = a;

	return wans;

      }

  }

}

where locate

(exp e, space sp, shape s, int dreg)

{

  ans ak;

  where w;

  ak = iskept(e);

  if (ak.discrim == inreg && (regalt(ak) == 0)) {

    where w;

    w = locate1(e, sp, s, dreg);

    return w;

  }

  else {			/* e has been evaluated into a register */

    w.answhere = ak;

    w.ashwhere = ashof(s);

  }

  return w;

}