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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 15:55:47 $
$Revision: 1.1.1.1 $
$Log: unroll.c,v $
 * Revision 1.1.1.1  1998/01/17  15:55:47  release
 * First version to be checked into rolling release.
 *
 * Revision 1.2  1995/09/11  13:58:41  currie
 * gcc pedantry
 *
 * Revision 1.1  1995/04/06  10:44:05  currie
 * Initial revision
 *
***********************************************************************/



#include "config.h"
#include "common_types.h"
#include "basicread.h"
#include "exp.h"
#include "expmacs.h"
#include "tags.h"
#include "installglob.h"
#include "externs.h"
#include "check_id.h"
#include "check.h"
#include "me_fns.h"
#include "install_fns.h"
#include "shapemacs.h"
#include "unroll.h"

static int  unroll_complex PROTO_S ( ( exp, int, exp, int, exp, int ) ) ;

/* MACROS */

#define LIMIT 55
#define SIMPLE_LIMIT 0
#define UNROLL_MAX 16

#define UNROLL_BY 4


/* VARIABLES */
/* All variables initialised */

static exp names[LIMIT];        /* no init needed */ /* records the uses of the control variable */
static int names_index;         /* no init needed */
static int allow_double;        /* no init needed */ /* permit removal of internal test */
static int jumps_out;           /* no init needed */

/* PROCEDURES */

static int  uc_list
    PROTO_N ( (e, n, control, lia, ul, decr) )
    PROTO_T ( exp e X int n X exp control X int lia X exp ul X int decr )
{
  int   c = unroll_complex (e, n, control, lia, ul, decr);
  if (c < 0 || last (e))
    return c;
  return uc_list (bro (e), c, control, lia, ul, decr);
}

static int  unroll_complex
    PROTO_N ( (e, n, control, lia, ul, decr) )
    PROTO_T ( exp e X int n X exp control X int lia X exp ul X int decr )
{
  /* e = body - repeated statement less label */
  /* n = complexity maximum */
  /* control = variable declaration for control variable */
  /* lia = boolean, limit is aliased */
  /* ul = variable declaration for limit if not aliased */
  /* decr = unit to decrement by */
  if (n < 0)
    return - 1; /* complexity exceeded */

  if (son (e) == nilexp) {
    if (name(e) == goto_tag)
      allow_double = 0;         /* prevent removal of internal test */
    return n;
  };

  switch (name (e)) {
    case test_tag:
    case testbit_tag:
      if (!isunroll(pt(e))) {   /* flag set and cleared by cond_tag below */
        allow_double = 0;       /* prevent removal of internal test; jump out of loop */
      };
      return uc_list (son (e), n - decr, control, lia, ul, decr);
    case goto_tag:
      if (!isunroll(pt(e))) {   /* flag set and cleared by cond_tag below */
        allow_double = 0;       /* prevent removal of internal test; jump out of loop */
      };
      return n-1;
    case cond_tag:
      {
        int t;
        setunroll(bro(son(e)));         /* mark internal label */
        if (name(sh(son(e))) == bothd) {
          t = unroll_complex(son(e), n - (4*decr), control, lia, ul, 0);
          t = unroll_complex(bro(son(e)), t - decr, control, lia, ul, decr);
        }
        else {
          t = unroll_complex(son(e), n - decr, control, lia, ul, decr);
          t = unroll_complex(bro(son(e)), t - decr, control, lia, ul, decr);
        };
        clearunroll(bro(son(e)));       /* unmark it */
        return t;
      };
    case ass_tag:
    case assvol_tag:
      {
        exp assdest = son(e);   /* destination of assignment */
        if (name(assdest) == name_tag && son(assdest) == ul)
          allow_double = 0;     /* prevent removal of internal test; assigning to limit */
        if (lia) {
          if (name(assdest) == name_tag && !isvar(son(assdest)))
            allow_double = 0;   /* prevent removal of internal test; perhaps assigning to limit */
          if (name(assdest) == name_tag && !iscaonly(son(assdest)))
            allow_double = 0;   /* prevent removal of internal test; perhaps assigning to limit */
        };
        return uc_list (son (e), n - decr, control, lia, ul, decr);
      };
    case name_tag:
      if (son (e) == control) { /* is this the control variable? */
        exp t;
        if (!last (e) || name (bro (e)) != cont_tag)
          allow_double = 0;     /* any use but contents -> no test elim */
        else {  /* it is a cont */
          t = bro (e);
#if isalpha
          if (!last(t) || name(bro(t)) != chvar_tag ||
              last (bro(t)) || name (bro(bro (t))) != val_tag || !last (bro (bro(t))) ||
              name (bro (bro (bro(t)))) != offset_mult_tag)
            allow_double = 0;   /* not offset_mult -> no test elim */
          else
            names[names_index++] = bro(e);      /* record the use */
#else
          if (last (t) || name (bro (t)) != val_tag || !last (bro (t)) ||
              name (bro (bro (t))) != offset_mult_tag)
            allow_double = 0;   /* not offset_mult -> no test elim */
          else
            names[names_index++] = bro(e);      /* record the use */
#endif
        };
      };
      return n - decr;
    case apply_tag:
    case solve_tag:
      return - 1;       /* no unroll */
    case case_tag:
      return unroll_complex (son (e), n - decr, control, lia, ul, decr);
    case string_tag:
    case env_offset_tag:
    case general_env_offset_tag:
      return n - decr;  /* decrease the complexity count */
    case top_tag:
    case prof_tag:
    case clear_tag:
      return n;
    case labst_tag:
      return unroll_complex (bro (son (e)), n, control, lia, ul, decr);
    case seq_tag:
      return uc_list (son (e), n, control, lia, ul, decr);
    case round_tag:
    case fplus_tag:
    case fminus_tag:
    case fmult_tag:
    case fdiv_tag:
    case fabs_tag:
    case fneg_tag:
    case fpower_tag:
    case fmax_tag:
    case fmin_tag:
    case float_tag:
    case chfl_tag:
      return uc_list (son (e), n - (16*decr), control, lia, ul, decr);  /* heavy flpt ops */
    default:
      return uc_list (son (e), n - decr, control, lia, ul, decr);       /* other ops decrease complexity by 1 */
  };
}

void simple_unroll
    PROTO_N ( (candidate, body, inc, te) )
    PROTO_T ( exp candidate X exp body X exp inc X exp te )
{
    /* candidate = rep_tag */
    /* body = repeated statement less label, assignment and test */
    /* inc = the single assignment to the control variable */
    /* te = the final test - only jump to repeat label */
    exp second_body = copy (body);      /* repeated statement less label, assignment and test */
    exp second_inc = copy (inc);        /* assignment to control */
    exp second_test = copy (te);
    exp z = getexp (f_top, te, 0, nilexp, nilexp, 0, 0, 0);
    exp seq = getexp (f_top, bro (son (candidate)), 1,
        z, nilexp, 0, 0, seq_tag);
    exp cond_labst;
    exp cl1, mt;
    exp cond, f;
    exp * point;
    float freq = fno(bro(son(candidate)));

    no (son (bro (son (candidate))))--; /* decrease label count (increased by copy(te)) */

    setlast (second_inc);
    bro (second_inc) = z;
    clearlast (second_body);
    bro (second_body) = second_inc;
    clearlast (second_test);
    bro (second_test) = second_body;
    clearlast (inc);
    bro (inc) = second_test;
    clearlast (body);
    bro (body) = inc;
    son (z) = body;
    setlast (te);
    bro (te) = seq;
    bro (son (bro (son (candidate)))) = seq;

/*
candidate
        rep
        x       labst
                1 use   seq
                        0        te
                        body    inc     second_test     second_body     second_inc
*/

    cond_labst = getexp (f_top, nilexp, 1, nilexp, nilexp,
                         0, 0, labst_tag);
    fno(cond_labst) = (float) (freq / 20.0);
    mt = getexp (f_top, cond_labst, 1, nilexp, nilexp, 0, 0, top_tag);
    cl1 = getexp (f_top, mt, 0, nilexp, nilexp, 0, 1, clear_tag);
    son (cond_labst) = cl1;

    pt (second_test) = cond_labst;
    settest_number (second_test,
                   (int)int_inverse_ntest[test_number (te)]);

    cond = getexp (f_top, bro (candidate), (int)(last (candidate)),
        candidate, nilexp, 0, 0, cond_tag);
    bro (cond_labst) = cond;

    f = father (candidate);
    point = refto (f, candidate);
    *point = cond;

    clearlast (candidate);
    bro (candidate) = cond_labst;

/*
cond
        cond
        rep                             labst(ln)
        x       labst                   1 use   top
                1 use   seq
                        0        te
                        body    inc     second_test(invert, ln) second_body     second_inc

*/

    setunrolled (candidate);
    return;
}

static exp inc_offset
    PROTO_N ( (var, sha, konst, body, i) )
    PROTO_T ( exp var X shape sha X exp konst X exp body X int i )
{
  exp sum, t;
  exp id = son(var);
  exp rest = pt(id);
  body = copy(body);
  if (names_index > 0) {        /* count of offset_mult uses of control variable */
    t = pt(id);
    sum = me_u3(sha, copy(var), cont_tag);
    sum = hold_check(me_b3(sha, sum,
                             me_shint(sha, i*no(konst)), plus_tag));    /* variable + i */

    for (i = 0; i < names_index; ++i) {
      exp q = pt(t);
      exp b = bro(t);
      replace(bro(t), copy(sum), body); /* replace the offset_mults in body */
      kill_exp(b, b);
      t = q;
    };
    if (t != rest)
      failer("unroll failure");

    kill_exp(sum, sum);
  };
  return body;
}

void unroll_trans
    PROTO_N ( (candidate, body, inc, te, limit, nt, var, konst, reps, times) )
    PROTO_T ( exp candidate X exp body X exp inc X exp te X exp limit X
              int nt X exp var X exp konst X exp reps X int times )
{
  /* candidate = rep_tag */
  /* body = repeated statement less label, assignment and test */
  /* inc = the single assignment to the control variable */
  /* te = the final test - only jump to repeat label */
  /* limit = the limit exp */
  /* nt = the test number */
  /* var = name_tag for control variable */
  /* konst = the value added to the control variable */
  /* reps = current element of the repeat list */
  /* times = no of times to unroll */
  float freq = fno(bro(son(candidate)));
  if (allow_double && no(konst) == 1 &&         /* allow_double==0 prevents test elimination */
      (nt == (int)f_greater_than || nt == (int)f_greater_than_or_equal) &&
                /* the permitted tests - we are counting upwards */
      ((name(limit) == name_tag && !isvar(son(limit))) ||
         name(limit) == val_tag ||
        (name(limit) == cont_tag && name(son(limit)) == name_tag &&
            isvar(son(son(limit)))))    /* permitted forms of limit */
      ) {
                /* unroll and remove the internal increment and test */

    int i;
    shape sha = sh(konst);
    exp branches [UNROLL_MAX + 2];      /* 0 - (times-2) are preliminaries
                                           (times-1) is test out
                                           times is the loop
                                           (times+1) is the end */
    exp test_out = copy(te);            /* used to jump out after < times */
    exp temp, temp1, bc, repeater, lrep, res, id, temp2;
    exp new_c = me_shint(sha, times*no(konst)); /* used to increment the control variable */

    settest_number(test_out,
                   (int)int_inverse_ntest[test_number(test_out)]);

    for (i = 0; i < times + 2; ++i) {   /* set up labst for branches */
      exp lia = me_shint(sha, (((i > 1) && (i < (times-1))) || i >= times) ? 2: 1);
      exp li = getexp(f_bottom, nilexp, 0, lia, nilexp, 0, 0, labst_tag);
      fno(li) = (float) (freq / 20.0);
      name(lia) = clear_tag;
      clearlast(lia);
      branches[i] = li;
    };
    SET(branches);
    sh(branches[times+1]) = f_top;


    for (i = 0; i < times - 1; ++ i) {  /* set up preliminaries */
      exp sub = me_b3(f_top, copy(body), copy(inc), 0);
      exp seq = me_b3(f_bottom, sub,
                 getexp(f_bottom, nilexp, 0, nilexp, branches[i+1], 0, 0, goto_tag), seq_tag);
      bro(son(branches[i])) = seq;
      setlast(seq);
      bro(seq) = branches[i];
    };

    pt(test_out) = branches[times+1];
    temp = me_u3(f_top, test_out, 0);
    temp = me_b3(f_bottom, temp,
                 getexp(f_bottom, nilexp, 0, nilexp, branches[times], 0, 0, goto_tag), seq_tag);
    bro(son(branches[times-1])) = temp;
    setlast(temp);
    bro(temp) = branches[times-1];

    temp = copy(body);
    temp1 = temp;
    if (jumps_out) {
      bro(temp1) = copy(inc);
      clearlast(temp1);
      temp1 = bro(temp1);
    };
    for (i = 1; i < times - 1; ++i) {
      if (jumps_out)
        bro(temp1) = copy(body);
      else
        bro(temp1) = inc_offset(var, sha, konst, body, i);
      clearlast(temp1);
      temp1 = bro(temp1);
      if (jumps_out) {
        bro(temp1) = copy(inc);
        clearlast(temp1);
        temp1 = bro(temp1);
      };
    };
    bc = getexp(f_top, nilexp, 0, temp, nilexp, 0, 0, 0);
    setlast(temp1);
    bro(temp1) = bc;
    if (jumps_out)
      bc = me_b3(f_top, bc, copy(body), seq_tag);
    else {
      bc = me_b3(f_top, bc, inc_offset(var, sha, konst, body, i), seq_tag);
      kill_exp(body, body);
    };

    if (jumps_out)
      kill_exp(new_c, new_c);
    else
      replace(bro(son(bro(var))), new_c, new_c);        /* replace konst by times*konst */

    temp = me_b3(f_top, bc, inc, 0);
    temp = me_b3(f_top, temp, te, seq_tag);
    lrep = me_b3(f_top, me_shint(sha, 1), temp, labst_tag);
    fno(lrep) = freq / (float)times;
    name(son(lrep)) = clear_tag;
    repeater = me_b3(f_top, f_make_top(), lrep, rep_tag);
    son(reps) = repeater;
    pt(te) = lrep;      /* label in repeater */
    pt(test_out) = branches[times+1];

    temp = f_make_top();
    bro(son(branches[times+1])) = temp;
    setlast(temp);
    bro(temp) = branches[times+1];

    temp = me_u3(f_top, repeater, 0);
    temp = me_b3(f_bottom, temp,
                 getexp(f_bottom, nilexp, 0, nilexp, branches[times+1], 0, 0, goto_tag), seq_tag);
    bro(son(branches[times])) = temp;
    setlast(temp);
    bro(temp) = branches[times];

    temp = me_u3(sha, copy(var), cont_tag);
    temp1 = copy(limit);
    sh(temp1) = sha;
    temp = hold_check(me_b3(sha, temp1, temp, minus_tag));
    if (nt == (int)f_greater_than) {
      temp = hold_check(me_b3(sha, temp, me_shint(sha, 1), plus_tag));
    };
    temp = hold_check(me_b3(sha, temp,
                                 me_shint(sha, times-1), and_tag));

    id = me_startid(sha, temp, 0);
    temp = getexp(f_top, nilexp, 0, me_obtain(id), branches[times], 0, 0, test_tag);
    settest_number(temp, f_not_equal);
    bro(son(temp)) = me_shint(sha, 0);
    setlast(bro(son(temp)));
    bro(bro(son(temp))) = temp;
    temp1 = temp;

    for (i = 1; i < (times-1); ++i) {
      temp2 = getexp(f_top, nilexp, 0, me_obtain(id), branches[times-i-1], 0, 0, test_tag);
      settest_number(temp2, f_not_equal);
      bro(son(temp2)) = me_shint(sha, i);
      setlast(bro(son(temp2)));
      bro(bro(son(temp2))) = temp2;
      settest_number(temp, f_not_equal);
      clearlast(temp1);
      bro(temp1) = temp2;
      temp1 = temp2;
    };

    bc = getexp(f_top, nilexp, 0, temp, nilexp, 0, 0, 0);
    setlast(temp1);
    bro(temp1) = bc;
    bc = me_b3(f_bottom, bc,
         getexp(f_bottom, nilexp, 0, nilexp, branches[0], 0, 0, goto_tag), seq_tag);
    id = me_complete_id(id, bc);

    temp1 = id;
    for (i = 0; i < (times+2); ++i) {
      bro(temp1) = branches[i];
      clearlast(temp1);
      temp1 = bro(temp1);
    };
    res = getexp(f_top, nilexp, 0, id, nilexp, 0, 0, solve_tag);
    setlast(temp1);
    bro(temp1) = res;
    setunrolled(repeater);

    replace(candidate, res, res);
  }
#if is80x86
  else
    simple_unroll (candidate, body, inc, te);
#endif
  return;
}

void unroller
    PROTO_Z ()
{
  exp reps = repeat_list;
  exp candidate;
  exp labst;
  exp rb;


  while (reps != nilexp) {
    if (no (reps) == 0 && son (reps) != nilexp &&
        name (son (reps)) == rep_tag) {
      /* this is a leaf repeat node */
      candidate = son (reps);   /* this is the repeat */
      labst = bro (son (candidate));    /* the repeated statement */
      rb = bro (son (labst));   /* the repeated statement less label */

      if (name (son (candidate)) == top_tag &&
          no (son (labst)) == 1 &&
          name (rb) == seq_tag &&
          name (bro (son (rb))) == seq_tag) {
/*

        rep_tag
        top_tag labst_tag
                count           seq_tag
                                0        seq_tag

*/
        exp final = bro (son (rb));
        exp body = son (son (rb));
        exp ass = son (son (final));
        exp te = bro (son (final));
        if (name (ass) == ass_tag && name (te) == test_tag) {
/*

        rep_tag
        top_tag labst_tag
                count           seq_tag
                                0        seq_tag = final
                                body    0        test_tag = te
                                        ass_tag = ass

*/
          exp dest = son (ass);
          exp val = bro (dest);
          if (name (dest) == name_tag && isvar (son (dest)) &&
              iscaonly (son (dest)) && shape_size (sh (val)) == 32) {
/*

        rep_tag
        top_tag labst_tag
                count           seq_tag
                                0        seq_tag = final
                                body    0        test_tag = te
                                        ass_tag = ass
                                        name = dest     val (32)
                                        var & ca
*/
            if (name (val) == plus_tag && name (son (val)) == cont_tag &&
                name (son (son (val))) == name_tag &&
                son (son (son (val))) == son (dest) &&
                name (bro (son (val))) == val_tag) {
/*

        rep_tag
        top_tag labst_tag
                count           seq_tag
                                0        seq_tag = final
                                body    0        test_tag = te
                                        ass_tag = ass
                                        name = dest     plus_tag =val (32)
                                        var & ca        cont_tag        val_tag
                                                        name_tag -> dest
*/
              exp konst = bro (son (val));
              int   nt = (int)test_number (te);
              if (name (son (te)) == cont_tag &&
                  name (son (son (te))) == name_tag &&
                  pt (te) == labst &&
                  son (son (son (te))) == son (dest)) {
/*

        rep_tag
        top_tag labst_tag
                count   seq_tag
                        0        seq_tag = final
                        body    0                                        test_tag(nt, labst) = te
                                ass_tag = ass                           cont_tag
                                name = dest     plus_tag =val (32)      name_tag -> dest
                                var & ca        cont_tag val_tag = konst
                                                name_tag -> dest
*/
                int   count;
                exp limit = bro(son(te));
                exp unaliased_limit = nilexp;
                int limit_is_aliased = 0;

                if (name(limit) == cont_tag &&
                        name(son(limit)) == name_tag &&
                        isvar(son(son(limit)))) {
/*

        rep_tag
        top_tag labst_tag
                count   seq_tag
                        0        seq_tag = final
                        body    0                                        test_tag(nt, labst) = te
                                ass_tag = ass                           cont_tag        cont_tag = limit
                                name = dest     plus_tag =val (32)      name_tag -> dest
                                var & ca        cont_tag val_tag = konst
                                                name_tag -> dest
*/
                  if (iscaonly(son(son(limit))))
                    unaliased_limit = son(son(limit));
                  else
                    limit_is_aliased = 1;
                };

                names_index = 0;
                allow_double = 1;
                jumps_out = 0;
                count = unroll_complex (body, LIMIT, son (dest),
                                limit_is_aliased, unaliased_limit, 1);
                if (count >= 0) {
                  unroll_trans (candidate, body, ass, te,
                                limit, nt, dest, konst, reps, UNROLL_BY);
                };
              };
            }
            else {
              int count;
              names_index = 0;
              allow_double = 0;
              count = unroll_complex (body, SIMPLE_LIMIT, nilexp,
                                0, nilexp, 1);
              if (count >= 0) {
                simple_unroll(candidate, body, ass, te);
              };
            };
          };
        }
      };
    };
    reps = pt (reps);
  };
  return;
}