| 1 | /* Copyright (c) 1979 Regents of the University of California */ |
| 2 | # |
| 3 | /* |
| 4 | * pi - Pascal interpreter code translator |
| 5 | * |
| 6 | * Charles Haley, Bill Joy UCB |
| 7 | * Version 1.2 November 1978 |
| 8 | */ |
| 9 | |
| 10 | #include "whoami" |
| 11 | #include "0.h" |
| 12 | #include "tree.h" |
| 13 | #include "opcode.h" |
| 14 | |
| 15 | extern int flagwas; |
| 16 | /* |
| 17 | * Lvalue computes the address |
| 18 | * of a qualified name and |
| 19 | * leaves it on the stack. |
| 20 | */ |
| 21 | struct nl * |
| 22 | lvalue(r, modflag) |
| 23 | int *r, modflag; |
| 24 | { |
| 25 | register struct nl *p; |
| 26 | struct nl *firstp, *lastp; |
| 27 | register *c, *co; |
| 28 | int f, o; |
| 29 | /* |
| 30 | * Note that the local optimizations |
| 31 | * done here for offsets would more |
| 32 | * appropriately be done in put. |
| 33 | */ |
| 34 | int tr[2], trp[3]; |
| 35 | |
| 36 | if (r == NIL) |
| 37 | return (NIL); |
| 38 | if (nowexp(r)) |
| 39 | return (NIL); |
| 40 | if (r[0] != T_VAR) { |
| 41 | error("Variable required"); /* Pass mesgs down from pt of call ? */ |
| 42 | return (NIL); |
| 43 | } |
| 44 | firstp = p = lookup(r[2]); |
| 45 | if (p == NIL) |
| 46 | return (NIL); |
| 47 | c = r[3]; |
| 48 | if ((modflag & NOUSE) && !lptr(c)) |
| 49 | p->nl_flags = flagwas; |
| 50 | if (modflag & MOD) |
| 51 | p->nl_flags |= NMOD; |
| 52 | /* |
| 53 | * Only possibilities for p->class here |
| 54 | * are the named classes, i.e. CONST, TYPE |
| 55 | * VAR, PROC, FUNC, REF, or a WITHPTR. |
| 56 | */ |
| 57 | switch (p->class) { |
| 58 | case WITHPTR: |
| 59 | /* |
| 60 | * Construct the tree implied by |
| 61 | * the with statement |
| 62 | */ |
| 63 | trp[0] = T_LISTPP; |
| 64 | trp[1] = tr; |
| 65 | trp[2] = r[3]; |
| 66 | tr[0] = T_FIELD; |
| 67 | tr[1] = r[2]; |
| 68 | c = trp; |
| 69 | # ifdef PTREE |
| 70 | /* |
| 71 | * mung r[4] to say which field this T_VAR is |
| 72 | * for VarCopy |
| 73 | */ |
| 74 | r[4] = reclook( p -> type , r[2] ); |
| 75 | # endif |
| 76 | /* and fall through */ |
| 77 | case REF: |
| 78 | /* |
| 79 | * Obtain the indirect word |
| 80 | * of the WITHPTR or REF |
| 81 | * as the base of our lvalue |
| 82 | */ |
| 83 | # ifdef VAX |
| 84 | put2 ( O_RV4 | bn << 9 , p->value[0] ); |
| 85 | # endif |
| 86 | # ifdef PDP11 |
| 87 | put2(O_RV2 | bn << 9, p->value[0]); |
| 88 | # endif |
| 89 | f = 0; /* have an lv on stack */ |
| 90 | o = 0; |
| 91 | break; |
| 92 | case VAR: |
| 93 | f = 1; /* no lv on stack yet */ |
| 94 | o = p->value[0]; |
| 95 | break; |
| 96 | default: |
| 97 | error("%s %s found where variable required", classes[p->class], p->symbol); |
| 98 | return (NIL); |
| 99 | } |
| 100 | /* |
| 101 | * Loop and handle each |
| 102 | * qualification on the name |
| 103 | */ |
| 104 | if (c == NIL && (modflag&ASGN) && p->value[NL_FORV]) { |
| 105 | error("Can't modify the for variable %s in the range of the loop", p->symbol); |
| 106 | return (NIL); |
| 107 | } |
| 108 | for (; c != NIL; c = c[2]) { |
| 109 | co = c[1]; |
| 110 | if (co == NIL) |
| 111 | return (NIL); |
| 112 | lastp = p; |
| 113 | p = p->type; |
| 114 | if (p == NIL) |
| 115 | return (NIL); |
| 116 | switch (co[0]) { |
| 117 | case T_PTR: |
| 118 | /* |
| 119 | * Pointer qualification. |
| 120 | */ |
| 121 | lastp->nl_flags |= NUSED; |
| 122 | if (p->class != PTR && p->class != FILET) { |
| 123 | error("^ allowed only on files and pointers, not on %ss", nameof(p)); |
| 124 | goto bad; |
| 125 | } |
| 126 | if (f) |
| 127 | # ifdef VAX |
| 128 | put2 ( O_RV4 | bn << 9 , o ); |
| 129 | # endif |
| 130 | # ifdef PDP11 |
| 131 | put2(O_RV2 | bn<<9, o); |
| 132 | # endif |
| 133 | else { |
| 134 | if (o) |
| 135 | put2(O_OFF, o); |
| 136 | # ifdef VAX |
| 137 | put1 ( O_IND4 ); |
| 138 | # endif |
| 139 | # ifdef PDP11 |
| 140 | put1(O_IND2); |
| 141 | # endif |
| 142 | } |
| 143 | /* |
| 144 | * Pointer cannot be |
| 145 | * nil and file cannot |
| 146 | * be at end-of-file. |
| 147 | */ |
| 148 | put1(p->class == FILET ? O_FNIL : O_NIL); |
| 149 | f = o = 0; |
| 150 | continue; |
| 151 | case T_ARGL: |
| 152 | if (p->class != ARRAY) { |
| 153 | if (lastp == firstp) |
| 154 | error("%s is a %s, not a function", r[2], classes[firstp->class]); |
| 155 | else |
| 156 | error("Illegal function qualificiation"); |
| 157 | return (NIL); |
| 158 | } |
| 159 | recovered(); |
| 160 | error("Pascal uses [] for subscripting, not ()"); |
| 161 | case T_ARY: |
| 162 | if (p->class != ARRAY) { |
| 163 | error("Subscripting allowed only on arrays, not on %ss", nameof(p)); |
| 164 | goto bad; |
| 165 | } |
| 166 | if (f) |
| 167 | put2(O_LV | bn<<9, o); |
| 168 | else if (o) |
| 169 | put2(O_OFF, o); |
| 170 | switch (arycod(p, co[1])) { |
| 171 | case 0: |
| 172 | return (NIL); |
| 173 | case -1: |
| 174 | goto bad; |
| 175 | } |
| 176 | f = o = 0; |
| 177 | continue; |
| 178 | case T_FIELD: |
| 179 | /* |
| 180 | * Field names are just |
| 181 | * an offset with some |
| 182 | * semantic checking. |
| 183 | */ |
| 184 | if (p->class != RECORD) { |
| 185 | error(". allowed only on records, not on %ss", nameof(p)); |
| 186 | goto bad; |
| 187 | } |
| 188 | if (co[1] == NIL) |
| 189 | return (NIL); |
| 190 | p = reclook(p, co[1]); |
| 191 | if (p == NIL) { |
| 192 | error("%s is not a field in this record", co[1]); |
| 193 | goto bad; |
| 194 | } |
| 195 | # ifdef PTREE |
| 196 | /* |
| 197 | * mung co[3] to indicate which field |
| 198 | * this is for SelCopy |
| 199 | */ |
| 200 | co[3] = p; |
| 201 | # endif |
| 202 | if (modflag & MOD) |
| 203 | p->nl_flags |= NMOD; |
| 204 | if ((modflag & NOUSE) == 0 || lptr(c[2])) |
| 205 | p->nl_flags |= NUSED; |
| 206 | o += p->value[0]; |
| 207 | continue; |
| 208 | default: |
| 209 | panic("lval2"); |
| 210 | } |
| 211 | } |
| 212 | if (f) |
| 213 | put2(O_LV | bn<<9, o); |
| 214 | else if (o) |
| 215 | put2(O_OFF, o); |
| 216 | return (p->type); |
| 217 | bad: |
| 218 | cerror("Error occurred on qualification of %s", r[2]); |
| 219 | return (NIL); |
| 220 | } |
| 221 | |
| 222 | lptr(c) |
| 223 | register int *c; |
| 224 | { |
| 225 | register int *co; |
| 226 | |
| 227 | for (; c != NIL; c = c[2]) { |
| 228 | co = c[1]; |
| 229 | if (co == NIL) |
| 230 | return (NIL); |
| 231 | switch (co[0]) { |
| 232 | |
| 233 | case T_PTR: |
| 234 | return (1); |
| 235 | case T_ARGL: |
| 236 | return (0); |
| 237 | case T_ARY: |
| 238 | case T_FIELD: |
| 239 | continue; |
| 240 | default: |
| 241 | panic("lptr"); |
| 242 | } |
| 243 | } |
| 244 | return (0); |
| 245 | } |
| 246 | |
| 247 | /* |
| 248 | * Arycod does the |
| 249 | * code generation |
| 250 | * for subscripting. |
| 251 | */ |
| 252 | arycod(np, el) |
| 253 | struct nl *np; |
| 254 | int *el; |
| 255 | { |
| 256 | register struct nl *p, *ap; |
| 257 | int i, d, v, v1; |
| 258 | int w; |
| 259 | |
| 260 | p = np; |
| 261 | if (el == NIL) |
| 262 | return (0); |
| 263 | d = p->value[0]; |
| 264 | /* |
| 265 | * Check each subscript |
| 266 | */ |
| 267 | for (i = 1; i <= d; i++) { |
| 268 | if (el == NIL) { |
| 269 | error("Too few subscripts (%d given, %d required)", i-1, d); |
| 270 | return (-1); |
| 271 | } |
| 272 | p = p->chain; |
| 273 | ap = rvalue(el[1], NLNIL); |
| 274 | if (ap == NIL) |
| 275 | return (0); |
| 276 | if (incompat(ap, p->type, el[1])) { |
| 277 | cerror("Array index type incompatible with declared index type"); |
| 278 | if (d != 1) |
| 279 | cerror("Error occurred on index number %d", i); |
| 280 | return (-1); |
| 281 | } |
| 282 | w = aryconst(np, i); |
| 283 | if (opt('t') == 0) |
| 284 | switch (w) { |
| 285 | case 8: |
| 286 | w = 6; |
| 287 | case 4: |
| 288 | case 2: |
| 289 | case 1: |
| 290 | put2((width(ap) != 4 ? O_INX2P2 : O_INX4P2) | (w & ~1) << 7, ( short ) p->range[0]); |
| 291 | el = el[2]; |
| 292 | continue; |
| 293 | } |
| 294 | put(4, width(ap) != 4 ? O_INX2 : O_INX4,w,( short ) p->range[0], |
| 295 | ( short ) ( p->range[1] - p->range[0] ) ); |
| 296 | el = el[2]; |
| 297 | } |
| 298 | if (el != NIL) { |
| 299 | do { |
| 300 | el = el[2]; |
| 301 | i++; |
| 302 | } while (el != NIL); |
| 303 | error("Too many subscripts (%d given, %d required)", i-1, d); |
| 304 | return (-1); |
| 305 | } |
| 306 | return (1); |
| 307 | } |