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/*

    Copyright (c) 1993 Open Software Foundation, Inc.

    All Rights Reserved

    Permission to use, copy, modify, and distribute this software

    and its documentation for any purpose and without fee is hereby

    granted, provided that the above copyright notice appears in all

    copies and that both the copyright notice and this permission

    notice appear in supporting documentation.

    OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING

    ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

    PARTICULAR PURPOSE.

    IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR

    CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM

    LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,

    NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION

    WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

*/

/*

    		 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: 1998/02/04 15:49:08 $

$Revision: 1.2 $

$Log: regexps.c,v $

 * Revision 1.2  1998/02/04  15:49:08  release

 * Added OSF copyright message.

 *

 * Revision 1.1.1.1  1998/01/17  15:55:57  release

 * First version to be checked into rolling release.

 *

 * Revision 1.4  1996/11/18  15:50:28  pwe

 * correct alias with bitfields, and case odds

 *

 * Revision 1.3  1996/10/11  10:51:19  pwe

 * clear_dep_reg v current-env_tag

 *

 * Revision 1.2  1996/10/04  16:04:08  pwe

 * add banners and mod for PWE ownership

 *

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

#include "config.h"

#include "memtdf.h"

#include "codegen.h"

#include "maxminmacs.h"		/* for absval() */

#include "myassert.h"

#include "comment.h"

#include "regexps.h"

#include "flags.h"

#include "check.h"

struct regpeept

{

  ans inans;

  exp keptexp;

  bool iscont;

};

typedef struct regpeept regpeep;

#define FR_OFFSET		KEPT_FREG_OFFSET	/* 32 */

#define	LAST_ALL_REGS		(FR_OFFSET+FR_LAST)	/* 63 */

regpeep regexps[LAST_ALL_REGS+1];	/* [0:31] fix pt - [32:63] floating pt */

static bool sim_exp PROTO_S ((exp, exp));

/* both either floating or fixed and same size and alignment */

bool keep_eq_size PROTO_N ((as,bs)) PROTO_T (shape as X shape bs)

{

  bool as_flt = is_floating(name(as));

  bool bs_flt = is_floating(name(bs));

  if (as_flt != bs_flt)

    return 0;			/* dissimilar float/fixed */

  return (shape_size(as) == shape_size(bs) && shape_align(as) == shape_align(bs));

}

static bool sim_explist PROTO_N ((al,bl)) PROTO_T (exp al X exp bl)

{

  if (al == nilexp && bl == nilexp)

    return (1);

  if (al == nilexp || bl == nilexp)

    return (0);

  if (!sim_exp(al, bl))

    return (0);

  if (last(al) && last(bl))

    return (1);

  if (last(al) || last(bl))

    return (0);

  return (sim_explist(bro(al), bro(bl)));

}

static bool sim_exp PROTO_N ((a,b)) PROTO_T (exp a X exp b)

{

  /*

   * basically eq_exp except equal shapes requirement is weakened to equal

   * sizes and alignments

   */

  if (name(a) == name(b))

  {

    if (name(a) == name_tag)

    {

      /* See if both are name_tags for same ident

	 with same offsets and same size and alignment */

      return (son(a) == son(b) && no(a) == no(b) &&

	      keep_eq_size(sh(a), sh(b)));

    }

    /* If it is not is_a 

       OR 

       if they are not the same size and alignment and same

     register type 

     */

    if (!is_a(name(a)) || !keep_eq_size(sh(a), sh(b)))

    {

      return (0);

    }

    if(name(a)==float_tag)

    {

      return eq_exp(son(a),son(b));

      /* float_tag is special since we could have e.g float (-1 slongsh) float (-1 ulongsh) */

    }

    return (no(a) == no(b) && sim_explist(son(a), son(b)));

  }

  return (0);

}

void clear_all PROTO_Z ()

{

  /* forget all register<->exp associations */

  int i;

  for (i = 0; i <= LAST_ALL_REGS; i++)

  {

    regexps[i].keptexp = nilexp;

    setregalt(regexps[i].inans, 0);

  }

}

void clear_reg PROTO_N ((i)) PROTO_T (int i)

{

  /* forget reg i - exp association */

  i = absval(i);

  if (i >= 0 && i <= LAST_ALL_REGS)

  {

    regexps[i].keptexp = nilexp;

    setregalt(regexps[i].inans, 0);

  }

}

/* find if e has already been evaluated into a register low_reg..hi_reg 

   Register tracking:

   The array regexps[] is an array of regpeep structures

   The elements of the structure regpeep are :

   ans inans;     This helps specify where the exp came from 

   exp keptexp;   The exp 

   bool iscont;   This specifies whether or not

   */

static ans iskept_regrange PROTO_N ((e,low_reg,hi_reg)) PROTO_T (exp e X int low_reg X int hi_reg)

{

  int i;

  ans aa;

  setregalt(aa, 0);		/* nilans until we know better */

  /* reg tracking of unions unsafe, as views of location can differ */

  /* +++ improve this */

  if (name(sh(e)) == cpdhd)

  {

    return aa;

  }

  for (i = low_reg; i <= hi_reg; i++)

  {

    exp ke = regexps[i].keptexp;

    if (ke != nilexp)

    {

      /* There is an association with register i */

      bool isc = regexps[i].iscont;

      ASSERT(!IS_R_TMP(i));	/* should not track R_TMP */

      if (

	  ((!isc && sim_exp(ke, e)) ||

	   (name(e) == cont_tag && isc && keep_eq_size(sh(ke), sh(e))

	    && sim_exp(ke, son(e)) && al1(sh(son(e))) == al1(sh(ke)))

	   )

	)

      {

	aa = (regexps[i].inans);

	FULLCOMMENT4("iskept found 1: reg=%d isc=%d name(e)=%d name(son(e))=%d",

		     i, isc, name(e), name(son(e)));

	COMMENT1("iskept found: no = %d",no(e));

	switch (aa.discrim)

	{

	case notinreg:

	  {

	    if (!aa.val.instoreans.adval)

	    {

	      /*

	       * the expression is given indirectly - it may have also been

	       * loaded into a register

	       */

	      continue;

	    }

	    /* else ... */

	  }

	default:

	  return aa;

	}

      }

      else if (name(ke) == cont_tag && !isc)

      {

	ans aq;

	aq = regexps[i].inans;

	if (aq.discrim == notinreg)

	{

	  instore is;

	  is = insalt(aq);

	  if (!is.adval && is.b.offset == 0 && IS_FIXREG(is.b.base)

	      && sim_exp(son(ke), e))

	  {

	    /*

	     * the contents of req expression is here as a reg-offset

	     */

	    is.adval = 1;

	    setinsalt(aq, is);

	    FULLCOMMENT4("iskept found 2: reg=%d isc=%d name(e)=%d name(son(e))=%d",

			 i, isc, name(e), name(son(e)));

	    return aq;

	  }

	}

      }

      else if (name(ke) == reff_tag && !isc)

      {

	ans aq;

	aq = regexps[i].inans;

	if (aq.discrim == notinreg)

	{

	  instore is;

	  is = insalt(aq);

	  if (is.adval && is.b.offset == (no(ke) / 8)

	      && IS_FIXREG(is.b.base)

	      && sim_exp(son(ke), e))

	  {

	    /*

	     * a ref select of req expression is here as a reg-offset

	     */

	    is.adval = 1;

	    is.b.offset = 0;

	    setinsalt(aq, is);

	    FULLCOMMENT4("iskept found 3: reg=%d isc=%d name(e)=%d name(son(e))=%d",

			 i, isc, name(e), name(son(e)));

	    return aq;

	  }

	}

      }

    }

  }

  return aa;

}

/* find if e has already been evaluated into register 'reg' */

ans iskept_inreg PROTO_N ((e,reg)) PROTO_T (exp e X int reg)

{

  return iskept_regrange(e, reg, reg);

}

/* find if e has already been evaluated into a fixed point register */

ans iskept_reg PROTO_N ((e)) PROTO_T (exp e)

{

  return iskept_regrange(e, 0, R_LAST);

}

/* find if e has already been evaluated into a floating point register */

ans iskept_freg PROTO_N ((e)) PROTO_T (exp e)

{

  return iskept_regrange(e, FR_OFFSET, LAST_ALL_REGS);

}

/* find if e has already been evaluated into any register */

ans iskept PROTO_N ((e)) PROTO_T (exp e)

{

  return iskept_regrange(e, 0, LAST_ALL_REGS);

}

/* return reg if 'a' can is in fixed reg */

int ans_reg PROTO_N ((aa)) PROTO_T (ans aa)

{

  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);	/* no init to avoid IBM cc bug */

    if (is.adval && is.b.offset == 0)

    {

      /* the same expression has already been evaluated into a reg */

      return is.b.base;

    }

  }

  return R_NO_REG;

}

/* set up exp - address association */

void keepexp PROTO_N ((e,loc)) PROTO_T (exp e X ans loc)

{

  int pos=0;

  switch (loc.discrim)

  {

  case insomereg:

  case insomefreg:

    {

      fail("Keep ? reg");

    }

  case inreg:

    {

      pos = regalt(loc);

      break;

    }

  case infreg:

    {

      pos = fregalt(loc).fr + FR_OFFSET;

      break;

    }

  case notinreg:

    {

      pos = insalt(loc).b.base;

      if (!IS_FIXREG(pos))

	return;

    }

  }

  ASSERT(pos >= 0 && pos <= LAST_ALL_REGS);

  if (IS_R_TMP(pos))

    return;			/* don't track R_TMP which is used outside

				 * tracking scheme */

  regexps[pos].keptexp = e;

  regexps[pos].inans = loc;

  regexps[pos].iscont = 0;

  COMMENT2("keepexp : reg %d kept name is %d",pos,name(e));

}

/* set up cont(e)-reg association */

/* if 0=<reg<=31  this means a fixed point register

   if 31<reg<=63  this means a float point register single precision

   if -63<=reg<-31 this means a float point register double precision

   */

void keepcont PROTO_N ((e,reg)) PROTO_T (exp e X int reg)

{

  freg fr;

  int z = absval(reg);

  if (z >= FR_OFFSET)

  {

    fr.dble = (reg < 0);

    fr.fr = z - FR_OFFSET;

    setfregalt(regexps[z].inans, fr);

  }

  else

  {

    instore is;

    if (IS_R_TMP(z))

      return;			/* don't track R_TMP which is used outside

				 * tracking scheme */

    is.b.base = reg;

    is.b.offset = 0;

    is.adval = 1;

    setinsalt(regexps[z].inans, is);

  }

  ASSERT(z >= 0 && z <= LAST_ALL_REGS);

  regexps[z].keptexp = e;

  regexps[z].iscont = 1;

  COMMENT2("keepcont : reg %d kept name is %d",z,name(e));

}

/* keepreg keeps the exp e */

/* if 0=<reg<=31  this means a fixed point register

   if 31<reg<=63  this means a float point register single precision

   if -63<=reg<-31 this means a float point register double precision

   */

void keepreg PROTO_N ((e,reg)) PROTO_T (exp e X int reg)

{

  freg fr;

  int z = absval(reg);

  if (z >= FR_OFFSET)

  {

    /* It is a float register */

    /* HACK: if reg <0 then it is double 

       otherwise it is single precision */

    fr.dble = (reg < 0);

    fr.fr = z - FR_OFFSET;

    setfregalt(regexps[z].inans, fr);

  }

  else

  {

    instore is;

    if (IS_R_TMP(z))

    {

      return;			/* don't track R_TMP which is used outside

				 * tracking scheme */

    }

    is.b.base = reg;

    is.b.offset = 0;

    is.adval = 1;

    setinsalt(regexps[z].inans, is);

  }

  ASSERT(z >= 0 && z <= LAST_ALL_REGS);

  regexps[z].keptexp = e;

  regexps[z].iscont = 0;

  COMMENT3("keepreg : reg %d kept name is %d no %d",z,name(e),no(e));

}

bool couldeffect PROTO_S ((exp , exp ));

/* could 'e' be 'lhs' */

bool couldbe PROTO_N ((e,lhs)) PROTO_T (exp e X exp lhs )/* is var name_tag exp or 0 meaning cont */

{

  int ne = name(e);

  exp s = son(e);

  if (ne == name_tag)

  {

    if (lhs != 0 && s == son(lhs))

    {

      return 1;

    }

    if (isvar(s))

    {

      return (lhs == 0 && ( isglob(s) || isvis(s) ) );

    }

    if (IS_A_PROC(s))

      return (lhs == 0);

    if (son(s) == nilexp)

      return 1;

    return couldbe(son(s), lhs);

  }

  if (ne == cont_tag)

  {

    if (lhs != 0 && name(s) == name_tag && son(s) != nilexp)

    {

      return (son(s) == son(lhs) || isvis(son(lhs)) || isvis(son(s)));

    }

    return 1;

  }

  if (ne == reff_tag || ne == field_tag)

  {

    return couldbe(s, lhs);

  }

  if (ne == addptr_tag || ne == subptr_tag)

  {

    return (couldbe(s, lhs) || couldeffect(bro(s), lhs));

  }

  return 1;

}

/* could alteration to z effect e? */

bool couldeffect PROTO_N ((e,z)) PROTO_T (exp e X exp z )/* a name or zero */ 

{

  int ne = name(e);

  if (ne == cont_tag)

  {

    return couldbe(son(e), z);

  }

  if (ne == name_tag)

  {

    if (isvar(son(e)))

      return (z == 0 && isvis(son(e)));

    if (IS_A_PROC(son(e)))

      return 0;

    if (son(son(e)) == nilexp)

      return 1 /* could it happen? */ ;

    return couldeffect(son(son(e)), z);

  }

  if (ne < plus_tag || ne == contvol_tag)

    return 1;

  e = son(e);

  while (e != nilexp)

  {

    if (couldeffect(e, z))

      return 1;

    if (last(e))

      return 0;

    e = bro(e);

  }

  return 0;

}

/* does e depend on z */

bool dependson PROTO_N ((e,isc,z)) PROTO_T (exp e X bool isc X exp z)

{

  if (e == nilexp)

  {

    return 0;

  }

  for (;;)

  {

    if (name(z) == reff_tag || name(z) == addptr_tag ||

	name(z) == subptr_tag)

    {

      z = son(z);

    }

    if (name(z) != name_tag)

    {

      if (name(z) != cont_tag)

	return 1;

      z = 0;

      break;

    }

    if (isvar(son(z)))

      break;

    if (IS_A_PROC(son(z)))

    {

      z = 0;

      break;

    }

    if (son(son(z)) == nilexp)

      return 1;			/* can it happen? */

    z = son(son(z));

  }

  /* z is now unambiguous variable name or 0 meaning some contents */

  return ((isc) ? couldbe(e, z) : couldeffect(e, z));

}

/* remove association of any register which depends on lhs */

void clear_dep_reg PROTO_N ((lhs)) PROTO_T (exp lhs)

{

  int i;

  for (i = 0; i <= LAST_ALL_REGS; i++)

  {

    if (regexps[i].keptexp != nilexp)

    {

      switch(name(regexps[i].keptexp))

      {

      case val_tag:

      case null_tag:

      case real_tag:

      case string_tag:

      case name_tag:

      case current_env_tag:

	{

	  if (!regexps[i].iscont)

	  {

	    /* constant value, cannot be changed by assign */

	    continue;

	  }

	}

	/*FALLTHROUGH*/

      default:

	{

          if (dependson(regexps[i].keptexp, regexps[i].iscont, lhs))

          {

            FULLCOMMENT2("clear_dep_reg: reg=%d iscont=%d", i, regexps[i].iscont);

            regexps[i].keptexp = nilexp;

            setregalt(regexps[i].inans, 0);

          }

	}

      }

    }

  }

}