| 1 | /***** tl_spin: tl_rewrt.c *****/ |
| 2 | |
| 3 | /* Copyright (c) 1995-2003 by Lucent Technologies, Bell Laboratories. */ |
| 4 | /* All Rights Reserved. This software is for educational purposes only. */ |
| 5 | /* No guarantee whatsoever is expressed or implied by the distribution of */ |
| 6 | /* this code. Permission is given to distribute this code provided that */ |
| 7 | /* this introductory message is not removed and no monies are exchanged. */ |
| 8 | /* Software written by Gerard J. Holzmann. For tool documentation see: */ |
| 9 | /* http://spinroot.com/ */ |
| 10 | /* Send all bug-reports and/or questions to: bugs@spinroot.com */ |
| 11 | |
| 12 | /* Based on the translation algorithm by Gerth, Peled, Vardi, and Wolper, */ |
| 13 | /* presented at the PSTV Conference, held in 1995, Warsaw, Poland 1995. */ |
| 14 | |
| 15 | #include "tl.h" |
| 16 | |
| 17 | extern int tl_verbose; |
| 18 | |
| 19 | static Node *can = ZN; |
| 20 | |
| 21 | Node * |
| 22 | right_linked(Node *n) |
| 23 | { |
| 24 | if (!n) return n; |
| 25 | |
| 26 | if (n->ntyp == AND || n->ntyp == OR) |
| 27 | while (n->lft && n->lft->ntyp == n->ntyp) |
| 28 | { Node *tmp = n->lft; |
| 29 | n->lft = tmp->rgt; |
| 30 | tmp->rgt = n; |
| 31 | n = tmp; |
| 32 | } |
| 33 | |
| 34 | n->lft = right_linked(n->lft); |
| 35 | n->rgt = right_linked(n->rgt); |
| 36 | |
| 37 | return n; |
| 38 | } |
| 39 | |
| 40 | Node * |
| 41 | canonical(Node *n) |
| 42 | { Node *m; /* assumes input is right_linked */ |
| 43 | |
| 44 | if (!n) return n; |
| 45 | if ((m = in_cache(n)) != ZN) |
| 46 | return m; |
| 47 | |
| 48 | n->rgt = canonical(n->rgt); |
| 49 | n->lft = canonical(n->lft); |
| 50 | |
| 51 | return cached(n); |
| 52 | } |
| 53 | |
| 54 | Node * |
| 55 | push_negation(Node *n) |
| 56 | { Node *m; |
| 57 | |
| 58 | Assert(n->ntyp == NOT, n->ntyp); |
| 59 | |
| 60 | switch (n->lft->ntyp) { |
| 61 | case TRUE: |
| 62 | Debug("!true => false\n"); |
| 63 | releasenode(0, n->lft); |
| 64 | n->lft = ZN; |
| 65 | n->ntyp = FALSE; |
| 66 | break; |
| 67 | case FALSE: |
| 68 | Debug("!false => true\n"); |
| 69 | releasenode(0, n->lft); |
| 70 | n->lft = ZN; |
| 71 | n->ntyp = TRUE; |
| 72 | break; |
| 73 | case NOT: |
| 74 | Debug("!!p => p\n"); |
| 75 | m = n->lft->lft; |
| 76 | releasenode(0, n->lft); |
| 77 | n->lft = ZN; |
| 78 | releasenode(0, n); |
| 79 | n = m; |
| 80 | break; |
| 81 | case V_OPER: |
| 82 | Debug("!(p V q) => (!p U !q)\n"); |
| 83 | n->ntyp = U_OPER; |
| 84 | goto same; |
| 85 | case U_OPER: |
| 86 | Debug("!(p U q) => (!p V !q)\n"); |
| 87 | n->ntyp = V_OPER; |
| 88 | goto same; |
| 89 | #ifdef NXT |
| 90 | case NEXT: |
| 91 | Debug("!X -> X!\n"); |
| 92 | n->ntyp = NEXT; |
| 93 | n->lft->ntyp = NOT; |
| 94 | n->lft = push_negation(n->lft); |
| 95 | break; |
| 96 | #endif |
| 97 | case AND: |
| 98 | Debug("!(p && q) => !p || !q\n"); |
| 99 | n->ntyp = OR; |
| 100 | goto same; |
| 101 | case OR: |
| 102 | Debug("!(p || q) => !p && !q\n"); |
| 103 | n->ntyp = AND; |
| 104 | |
| 105 | same: m = n->lft->rgt; |
| 106 | n->lft->rgt = ZN; |
| 107 | |
| 108 | n->rgt = Not(m); |
| 109 | n->lft->ntyp = NOT; |
| 110 | m = n->lft; |
| 111 | n->lft = push_negation(m); |
| 112 | break; |
| 113 | } |
| 114 | |
| 115 | return rewrite(n); |
| 116 | } |
| 117 | |
| 118 | static void |
| 119 | addcan(int tok, Node *n) |
| 120 | { Node *m, *prev = ZN; |
| 121 | Node **ptr; |
| 122 | Node *N; |
| 123 | Symbol *s, *t; int cmp; |
| 124 | |
| 125 | if (!n) return; |
| 126 | |
| 127 | if (n->ntyp == tok) |
| 128 | { addcan(tok, n->rgt); |
| 129 | addcan(tok, n->lft); |
| 130 | return; |
| 131 | } |
| 132 | |
| 133 | N = dupnode(n); |
| 134 | if (!can) |
| 135 | { can = N; |
| 136 | return; |
| 137 | } |
| 138 | |
| 139 | s = DoDump(N); |
| 140 | if (can->ntyp != tok) /* only one element in list so far */ |
| 141 | { ptr = &can; |
| 142 | goto insert; |
| 143 | } |
| 144 | |
| 145 | /* there are at least 2 elements in list */ |
| 146 | prev = ZN; |
| 147 | for (m = can; m->ntyp == tok && m->rgt; prev = m, m = m->rgt) |
| 148 | { t = DoDump(m->lft); |
| 149 | if (t != ZS) |
| 150 | cmp = strcmp(s->name, t->name); |
| 151 | else |
| 152 | cmp = 0; |
| 153 | if (cmp == 0) /* duplicate */ |
| 154 | return; |
| 155 | if (cmp < 0) |
| 156 | { if (!prev) |
| 157 | { can = tl_nn(tok, N, can); |
| 158 | return; |
| 159 | } else |
| 160 | { ptr = &(prev->rgt); |
| 161 | goto insert; |
| 162 | } } } |
| 163 | |
| 164 | /* new entry goes at the end of the list */ |
| 165 | ptr = &(prev->rgt); |
| 166 | insert: |
| 167 | t = DoDump(*ptr); |
| 168 | cmp = strcmp(s->name, t->name); |
| 169 | if (cmp == 0) /* duplicate */ |
| 170 | return; |
| 171 | if (cmp < 0) |
| 172 | *ptr = tl_nn(tok, N, *ptr); |
| 173 | else |
| 174 | *ptr = tl_nn(tok, *ptr, N); |
| 175 | } |
| 176 | |
| 177 | static void |
| 178 | marknode(int tok, Node *m) |
| 179 | { |
| 180 | if (m->ntyp != tok) |
| 181 | { releasenode(0, m->rgt); |
| 182 | m->rgt = ZN; |
| 183 | } |
| 184 | m->ntyp = -1; |
| 185 | } |
| 186 | |
| 187 | Node * |
| 188 | Canonical(Node *n) |
| 189 | { Node *m, *p, *k1, *k2, *prev, *dflt = ZN; |
| 190 | int tok; |
| 191 | |
| 192 | if (!n) return n; |
| 193 | |
| 194 | tok = n->ntyp; |
| 195 | if (tok != AND && tok != OR) |
| 196 | return n; |
| 197 | |
| 198 | can = ZN; |
| 199 | addcan(tok, n); |
| 200 | #if 0 |
| 201 | Debug("\nA0: "); Dump(can); |
| 202 | Debug("\nA1: "); Dump(n); Debug("\n"); |
| 203 | #endif |
| 204 | releasenode(1, n); |
| 205 | |
| 206 | /* mark redundant nodes */ |
| 207 | if (tok == AND) |
| 208 | { for (m = can; m; m = (m->ntyp == AND) ? m->rgt : ZN) |
| 209 | { k1 = (m->ntyp == AND) ? m->lft : m; |
| 210 | if (k1->ntyp == TRUE) |
| 211 | { marknode(AND, m); |
| 212 | dflt = True; |
| 213 | continue; |
| 214 | } |
| 215 | if (k1->ntyp == FALSE) |
| 216 | { releasenode(1, can); |
| 217 | can = False; |
| 218 | goto out; |
| 219 | } } |
| 220 | for (m = can; m; m = (m->ntyp == AND) ? m->rgt : ZN) |
| 221 | for (p = can; p; p = (p->ntyp == AND) ? p->rgt : ZN) |
| 222 | { if (p == m |
| 223 | || p->ntyp == -1 |
| 224 | || m->ntyp == -1) |
| 225 | continue; |
| 226 | k1 = (m->ntyp == AND) ? m->lft : m; |
| 227 | k2 = (p->ntyp == AND) ? p->lft : p; |
| 228 | |
| 229 | if (isequal(k1, k2)) |
| 230 | { marknode(AND, p); |
| 231 | continue; |
| 232 | } |
| 233 | if (anywhere(OR, k1, k2)) |
| 234 | { marknode(AND, p); |
| 235 | continue; |
| 236 | } |
| 237 | } } |
| 238 | if (tok == OR) |
| 239 | { for (m = can; m; m = (m->ntyp == OR) ? m->rgt : ZN) |
| 240 | { k1 = (m->ntyp == OR) ? m->lft : m; |
| 241 | if (k1->ntyp == FALSE) |
| 242 | { marknode(OR, m); |
| 243 | dflt = False; |
| 244 | continue; |
| 245 | } |
| 246 | if (k1->ntyp == TRUE) |
| 247 | { releasenode(1, can); |
| 248 | can = True; |
| 249 | goto out; |
| 250 | } } |
| 251 | for (m = can; m; m = (m->ntyp == OR) ? m->rgt : ZN) |
| 252 | for (p = can; p; p = (p->ntyp == OR) ? p->rgt : ZN) |
| 253 | { if (p == m |
| 254 | || p->ntyp == -1 |
| 255 | || m->ntyp == -1) |
| 256 | continue; |
| 257 | k1 = (m->ntyp == OR) ? m->lft : m; |
| 258 | k2 = (p->ntyp == OR) ? p->lft : p; |
| 259 | |
| 260 | if (isequal(k1, k2)) |
| 261 | { marknode(OR, p); |
| 262 | continue; |
| 263 | } |
| 264 | if (anywhere(AND, k1, k2)) |
| 265 | { marknode(OR, p); |
| 266 | continue; |
| 267 | } |
| 268 | } } |
| 269 | for (m = can, prev = ZN; m; ) /* remove marked nodes */ |
| 270 | { if (m->ntyp == -1) |
| 271 | { k2 = m->rgt; |
| 272 | releasenode(0, m); |
| 273 | if (!prev) |
| 274 | { m = can = can->rgt; |
| 275 | } else |
| 276 | { m = prev->rgt = k2; |
| 277 | /* if deleted the last node in a chain */ |
| 278 | if (!prev->rgt && prev->lft |
| 279 | && (prev->ntyp == AND || prev->ntyp == OR)) |
| 280 | { k1 = prev->lft; |
| 281 | prev->ntyp = prev->lft->ntyp; |
| 282 | prev->sym = prev->lft->sym; |
| 283 | prev->rgt = prev->lft->rgt; |
| 284 | prev->lft = prev->lft->lft; |
| 285 | releasenode(0, k1); |
| 286 | } |
| 287 | } |
| 288 | continue; |
| 289 | } |
| 290 | prev = m; |
| 291 | m = m->rgt; |
| 292 | } |
| 293 | out: |
| 294 | #if 0 |
| 295 | Debug("A2: "); Dump(can); Debug("\n"); |
| 296 | #endif |
| 297 | if (!can) |
| 298 | { if (!dflt) |
| 299 | fatal("cannot happen, Canonical", (char *) 0); |
| 300 | return dflt; |
| 301 | } |
| 302 | |
| 303 | return can; |
| 304 | } |