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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.

*/

/*

$Log: guard.c,v $

 * Revision 1.1.1.1  1998/01/17  15:56:02  release

 * First version to be checked into rolling release.

 *

 * Revision 1.2  1995/12/18  13:11:26  wfs

 * Put hppatrans uder cvs control. Major Changes made since last release

 * include:

 * (i) PIC code generation.

 * (ii) Profiling.

 * (iii) Dynamic Initialization.

 * (iv) Debugging of Exception Handling and Diagnostics.

 *

 * Revision 5.0  1995/08/25  13:42:58  wfs

 * Preperation for August 25 Glue release

 *

 * Revision 3.4  1995/08/25  09:31:40  wfs

 * *** empty log message ***

 *

 * Revision 3.4  1995/08/25  09:31:40  wfs

 * *** empty log message ***

 *

 * Revision 3.1  95/04/10  16:26:36  16:26:36  wfs (William Simmonds)

 * Apr95 tape version.

 * 

 * Revision 3.0  95/03/30  11:17:16  11:17:16  wfs (William Simmonds)

 * Mar95 tape version with CRCR95_178 bug fix.

 * 

 * Revision 2.0  95/03/15  15:27:04  15:27:04  wfs (William Simmonds)

 * spec 3.1 changes implemented, tests outstanding.

 * 

 * Revision 1.1  95/01/11  13:08:43  13:08:43  wfs (William Simmonds)

 * Initial revision

 * 

*/

#define  HPPATRANS_CODE

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

		 guard.c

	These routines protect registers from future use. The type

involved is space which consists of two long ints with bit patterns

taken to represent usage of temporary fixed and floating

point registers. These bits are used in the procedure

getregs which understands a clear bit to mean that the corresponding

register is free for use.

	The procedures are widely used in make_code which may use

getreg to choose a register to contain the result of an expression.

If this expression is the first operand of a binary operation (say)

then the register is guarded, producing another space which will be

used by make_code for the second operand.

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

#include "config.h"

#include "regmacs.h"

#include "procrec.h"

#include "addrtypes.h"

#include "tempdecs.h"

#include "comment.h"

#include "guard.h"

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

The integer parameter to procedures guardreg and guardfreg

is taken to be a register which needs to be protected. For floating point

registers a factor of 2 is involved. The corresponding bit in the appropriate field of the

space i.e fixed or float, is therefore set.

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

space guardreg 

    PROTO_N ( ( r, sp ) )

    PROTO_T ( int r X space sp )

{

  if (IS_TREG(r))

  {

    sp.fixed |= RMASK(r);

  }				/* set bit in the fixed field of sp */

  return sp;

}

space guardfreg 

    PROTO_N ( ( r, sp ) )

    PROTO_T ( int r X space sp )

{

  if (IS_FLT_TREG(r))		/* r is a floating point t reg */

  {

    sp.flt |= RMASK(r);

  }				/* set bit in the flt field of sp */

  return sp;

}

/*

 * needreg & needfreg are like guardreg & guardfreg,

 * except it is an error if the reg is alread in use.

 * Used, eg, when claiming regs that will be damaged, as in a call.

 */

space needreg 

    PROTO_N ( ( r, sp ) )

    PROTO_T ( int r X space sp )

{

  /* tempdec() can allocate t regs if dead over calls, so dont fail */

#if 0 /* !!!! */

  if (!(tempdecopt && IS_TREG(r)) && (sp.fixed & RMASK(r)) != 0)

  {

    comment1("needreg: %d", r);

    fail("needreg: fixed reg already in use");

  }

#endif

  return guardreg(r, sp);

}

space needfreg 

    PROTO_N ( ( r, sp ) )

    PROTO_T ( int r X space sp )

{

#if 0 /* !!!! */

  /* tempdec() can allocate t regs if dead over calls, so dont fail */

  if (!(tempdecopt && IS_FLT_TREG(r)) && (sp.flt & RMASK(r)) != 0)

  {

    comment1("needfreg: %d", r);

    fail("needfreg: float reg already in use");

  }

#endif

  return guardreg(r, sp);

}

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

The procedure guard may also protect a register involved in

addressing depending on the value of the parameter of type where. This is a

union of a fixpnt reg , a float reg and an instore value. In the latter case the

register involved in the addressing can be deduced from the base field of the

instore value. These types are defined in addrtypes.h.

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

space guard 

    PROTO_N ( ( w, sp ) )

    PROTO_T ( where w X space sp )

{

  switch (discrim ( w.answhere ) )

  {

    case inreg:

    {

      int r = regalt(w.answhere);

      if (IS_TREG(r))

      {

	sp.fixed |= RMASK(r);

      }				/* guard reg */

      return sp;

    }

  case infreg:

    {

      int r = fregalt(w.answhere).fr;

      if (IS_FLT_TREG(r))

      {

	sp.flt |= RMASK(r);

      }				/* guard freg */

      return sp;

    }

#if USE_BITAD

  case bitad:

#endif

  case notinreg:

    {

      int r = insalt(w.answhere).b.base;

      if (IS_TREG(r))

      {

	sp.fixed |= RMASK(r);

      }

      /* guard fixed point t reg used as base of address */

      return sp;

    }

  case insomereg:

  case insomefreg:

    {

      comment1("guard: BAD discrim %d", discrim ( w.answhere ) );

      fail("guard: Guard ? reg");

      return sp;

    }

  default:

    {

      comment1("guard: BAD discrim %d", discrim ( w.answhere ) );

      fail("guard: not in switch");

      return sp;

    }

  }

}