| 1 | # |
| 2 | /* |
| 3 | * C compiler |
| 4 | * |
| 5 | * |
| 6 | */ |
| 7 | |
| 8 | #include "c0.h" |
| 9 | |
| 10 | /* |
| 11 | * Called from tree, this routine takes the top 1, 2, or 3 |
| 12 | * operands on the expression stack, makes a new node with |
| 13 | * the operator op, and puts it on the stack. |
| 14 | * Essentially all the work is in inserting |
| 15 | * appropriate conversions. |
| 16 | */ |
| 17 | build(op) |
| 18 | { |
| 19 | register int t1; |
| 20 | int t2, t; |
| 21 | register struct tnode *p1, *p2; |
| 22 | struct tnode *p3; |
| 23 | int dope, leftc, cvn, pcvn; |
| 24 | |
| 25 | /* |
| 26 | * a[i] => *(a+i) |
| 27 | */ |
| 28 | if (op==LBRACK) { |
| 29 | build(PLUS); |
| 30 | op = STAR; |
| 31 | } |
| 32 | dope = opdope[op]; |
| 33 | if ((dope&BINARY)!=0) { |
| 34 | p2 = chkfun(disarray(*--cp)); |
| 35 | t2 = p2->type; |
| 36 | } |
| 37 | p1 = *--cp; |
| 38 | /* |
| 39 | * sizeof gets turned into a number here. |
| 40 | */ |
| 41 | if (op==SIZEOF) { |
| 42 | t1 = cblock(length(p1)); |
| 43 | t1->type = UNSIGN; |
| 44 | *cp++ = t1; |
| 45 | return; |
| 46 | } |
| 47 | if (op!=AMPER) { |
| 48 | p1 = disarray(p1); |
| 49 | if (op!=CALL) |
| 50 | p1 = chkfun(p1); |
| 51 | } |
| 52 | t1 = p1->type; |
| 53 | pcvn = 0; |
| 54 | t = INT; |
| 55 | switch (op) { |
| 56 | |
| 57 | case CAST: |
| 58 | if ((t1&XTYPE)==FUNC || (t1&XTYPE)==ARRAY) |
| 59 | error("Disallowed conversion"); |
| 60 | if (t1==UNSIGN && t2==CHAR) { |
| 61 | t2 = INT; |
| 62 | p2 = block(AND,INT,NULL,NULL,p2,cblock(0377)); |
| 63 | } |
| 64 | break; |
| 65 | |
| 66 | /* end of expression */ |
| 67 | case 0: |
| 68 | *cp++ = p1; |
| 69 | return; |
| 70 | |
| 71 | /* no-conversion operators */ |
| 72 | case QUEST: |
| 73 | if (p2->op!=COLON) |
| 74 | error("Illegal conditional"); |
| 75 | else |
| 76 | if (fold(QUEST, p1, p2)) |
| 77 | return; |
| 78 | |
| 79 | case SEQNC: |
| 80 | t = t2; |
| 81 | |
| 82 | case COMMA: |
| 83 | case LOGAND: |
| 84 | case LOGOR: |
| 85 | *cp++ = block(op, t, NULL, NULL, p1, p2); |
| 86 | return; |
| 87 | |
| 88 | case EXCLA: |
| 89 | t1 = INT; |
| 90 | break; |
| 91 | |
| 92 | case CALL: |
| 93 | if ((t1&XTYPE) != FUNC) |
| 94 | error("Call of non-function"); |
| 95 | *cp++ = block(CALL,decref(t1),p1->subsp,p1->strp,p1,p2); |
| 96 | return; |
| 97 | |
| 98 | case STAR: |
| 99 | if ((t1&XTYPE) == FUNC) |
| 100 | error("Illegal indirection"); |
| 101 | *cp++ = block(STAR, decref(t1), p1->subsp, p1->strp, p1); |
| 102 | return; |
| 103 | |
| 104 | case AMPER: |
| 105 | if (p1->op==NAME || p1->op==STAR) { |
| 106 | *cp++ = block(op,incref(t1),p1->subsp,p1->strp,p1); |
| 107 | return; |
| 108 | } |
| 109 | error("Illegal lvalue"); |
| 110 | break; |
| 111 | |
| 112 | /* |
| 113 | * a.b goes to (&a)->b |
| 114 | */ |
| 115 | case DOT: |
| 116 | if (p1->op==CALL && t1==STRUCT) { |
| 117 | t1 = incref(t1); |
| 118 | setype(p1, t1, p1); |
| 119 | } else { |
| 120 | *cp++ = p1; |
| 121 | build(AMPER); |
| 122 | p1 = *--cp; |
| 123 | } |
| 124 | |
| 125 | /* |
| 126 | * In a->b, a is given the type ptr-to-structure element; |
| 127 | * then the offset is added in without conversion; |
| 128 | * then * is tacked on to access the member. |
| 129 | */ |
| 130 | case ARROW: |
| 131 | if (p2->op!=NAME || p2->tr1->hclass!=MOS) { |
| 132 | error("Illegal structure ref"); |
| 133 | *cp++ = p1; |
| 134 | return; |
| 135 | } |
| 136 | if (t2==INT && p2->tr1->hflag&FFIELD) |
| 137 | t2 = UNSIGN; |
| 138 | t = incref(t2); |
| 139 | chkw(p1, -1); |
| 140 | setype(p1, t, p2); |
| 141 | *cp++ = block(PLUS,t,p2->subsp,p2->strp,p1,cblock(p2->tr1->hoffset)); |
| 142 | build(STAR); |
| 143 | if (p2->tr1->hflag&FFIELD) |
| 144 | *cp++ = block(FSEL,UNSIGN,NULL,NULL,*--cp,p2->tr1->hstrp); |
| 145 | return; |
| 146 | } |
| 147 | if ((dope&LVALUE)!=0) |
| 148 | chklval(p1); |
| 149 | if ((dope&LWORD)!=0) |
| 150 | chkw(p1, LONG); |
| 151 | if ((dope&RWORD)!=0) |
| 152 | chkw(p2, LONG); |
| 153 | if ((dope&BINARY)==0) { |
| 154 | if (op==ITOF) |
| 155 | t1 = DOUBLE; |
| 156 | else if (op==FTOI) |
| 157 | t1 = INT; |
| 158 | if (!fold(op, p1, 0)) |
| 159 | *cp++ = block(op,t1,p1->subsp,p1->strp,p1); |
| 160 | return; |
| 161 | } |
| 162 | cvn = 0; |
| 163 | if (t1==STRUCT || t2==STRUCT) { |
| 164 | if (t1!=t2 || p1->strp != p2->strp) |
| 165 | error("Incompatible structures"); |
| 166 | cvn = 0; |
| 167 | } else |
| 168 | cvn = cvtab[lintyp(t1)][lintyp(t2)]; |
| 169 | leftc = (cvn>>4)&017; |
| 170 | cvn =& 017; |
| 171 | t = leftc? t2:t1; |
| 172 | if ((t==INT||t==CHAR) && (t1==UNSIGN||t2==UNSIGN)) |
| 173 | t = UNSIGN; |
| 174 | if (dope&ASSGOP || op==CAST) { |
| 175 | t = t1; |
| 176 | if (op==ASSIGN || op==CAST) { |
| 177 | if (cvn==ITP||cvn==PTI) |
| 178 | cvn = leftc = 0; |
| 179 | else if (cvn==LTP) { |
| 180 | if (leftc==0) |
| 181 | cvn = LTI; |
| 182 | else { |
| 183 | cvn = ITL; |
| 184 | leftc = 0; |
| 185 | } |
| 186 | } |
| 187 | } |
| 188 | if (leftc) |
| 189 | cvn = leftc; |
| 190 | leftc = 0; |
| 191 | } else if (op==COLON || op==MAX || op==MIN) { |
| 192 | if (t1>=PTR && t1==t2) |
| 193 | cvn = 0; |
| 194 | if (op!=COLON && (t1>=PTR || t2>=PTR)) |
| 195 | op =+ MAXP-MAX; |
| 196 | } else if (dope&RELAT) { |
| 197 | if (op>=LESSEQ && (t1>=PTR||t2>=PTR||(t1==UNSIGN||t2==UNSIGN) |
| 198 | && (t==INT||t==CHAR||t==UNSIGN))) |
| 199 | op =+ LESSEQP-LESSEQ; |
| 200 | if (cvn==ITP || cvn==PTI) |
| 201 | cvn = 0; |
| 202 | } |
| 203 | if (cvn==PTI) { |
| 204 | cvn = 0; |
| 205 | if (op==MINUS) { |
| 206 | t = INT; |
| 207 | pcvn++; |
| 208 | } else { |
| 209 | if (t1!=t2 || t1!=(PTR+CHAR)) |
| 210 | cvn = XX; |
| 211 | } |
| 212 | } |
| 213 | if (cvn) { |
| 214 | t1 = plength(p1); |
| 215 | t2 = plength(p2); |
| 216 | if (cvn==XX || (cvn==PTI&&t1!=t2)) |
| 217 | error("Illegal conversion"); |
| 218 | else if (leftc) |
| 219 | p1 = convert(p1, t, cvn, t2); |
| 220 | else |
| 221 | p2 = convert(p2, t, cvn, t1); |
| 222 | } |
| 223 | if (dope&RELAT) |
| 224 | t = INT; |
| 225 | if (t==FLOAT) |
| 226 | t = DOUBLE; |
| 227 | if (t==CHAR) |
| 228 | t = INT; |
| 229 | if (op==CAST) { |
| 230 | if (t!=DOUBLE && (t!=INT || p2->type!=CHAR)) { |
| 231 | p2->type = t; |
| 232 | p2->subsp = p1->subsp; |
| 233 | p2->strp = p1->strp; |
| 234 | } |
| 235 | if (t==INT && p1->type==CHAR) |
| 236 | p2 = block(ITOC, INT, NULL, NULL, p2); |
| 237 | *cp++ = p2; |
| 238 | return; |
| 239 | } |
| 240 | if (fold(op, p1, p2)==0) { |
| 241 | p3 = leftc?p2:p1; |
| 242 | *cp++ = block(op, t, p3->subsp, p3->strp, p1, p2); |
| 243 | } |
| 244 | if (pcvn && t1!=(PTR+CHAR)) { |
| 245 | p1 = *--cp; |
| 246 | *cp++ = convert(p1, 0, PTI, plength(p1->tr1)); |
| 247 | } |
| 248 | } |
| 249 | |
| 250 | /* |
| 251 | * Generate the appropriate conversion operator. |
| 252 | */ |
| 253 | struct tnode * |
| 254 | convert(p, t, cvn, len) |
| 255 | struct tnode *p; |
| 256 | { |
| 257 | register int op; |
| 258 | |
| 259 | op = cvntab[cvn]; |
| 260 | if (opdope[op]&BINARY) { |
| 261 | if (len==0) |
| 262 | error("Illegal conversion"); |
| 263 | return(block(op, t, NULL, NULL, p, cblock(len))); |
| 264 | } |
| 265 | return(block(op, t, NULL, NULL, p)); |
| 266 | } |
| 267 | |
| 268 | /* |
| 269 | * Traverse an expression tree, adjust things |
| 270 | * so the types of things in it are consistent |
| 271 | * with the view that its top node has |
| 272 | * type at. |
| 273 | * Used with structure references. |
| 274 | */ |
| 275 | setype(ap, at, anewp) |
| 276 | struct tnode *ap, *anewp; |
| 277 | { |
| 278 | register struct tnode *p, *newp; |
| 279 | register t; |
| 280 | |
| 281 | p = ap; |
| 282 | t = at; |
| 283 | newp = anewp; |
| 284 | for (;; p = p->tr1) { |
| 285 | p->subsp = newp->subsp; |
| 286 | p->strp = newp->strp; |
| 287 | p->type = t; |
| 288 | if (p->op==AMPER) |
| 289 | t = decref(t); |
| 290 | else if (p->op==STAR) |
| 291 | t = incref(t); |
| 292 | else if (p->op!=PLUS) |
| 293 | break; |
| 294 | } |
| 295 | } |
| 296 | |
| 297 | /* |
| 298 | * A mention of a function name is turned into |
| 299 | * a pointer to that function. |
| 300 | */ |
| 301 | struct tnode * |
| 302 | chkfun(ap) |
| 303 | struct tnode *ap; |
| 304 | { |
| 305 | register struct tnode *p; |
| 306 | register int t; |
| 307 | |
| 308 | p = ap; |
| 309 | if (((t = p->type)&XTYPE)==FUNC && p->op!=ETYPE) |
| 310 | return(block(AMPER,incref(t),p->subsp,p->strp,p)); |
| 311 | return(p); |
| 312 | } |
| 313 | |
| 314 | /* |
| 315 | * A mention of an array is turned into |
| 316 | * a pointer to the base of the array. |
| 317 | */ |
| 318 | struct tnode * |
| 319 | disarray(ap) |
| 320 | struct tnode *ap; |
| 321 | { |
| 322 | register int t; |
| 323 | register struct tnode *p; |
| 324 | |
| 325 | p = ap; |
| 326 | /* check array & not MOS and not typer */ |
| 327 | if (((t = p->type)&XTYPE)!=ARRAY || p->op==NAME&&p->tr1->hclass==MOS |
| 328 | || p->op==ETYPE) |
| 329 | return(p); |
| 330 | p->subsp++; |
| 331 | *cp++ = p; |
| 332 | setype(p, decref(t), p); |
| 333 | build(AMPER); |
| 334 | return(*--cp); |
| 335 | } |
| 336 | |
| 337 | /* |
| 338 | * make sure that p is a ptr to a node |
| 339 | * with type int or char or 'okt.' |
| 340 | * okt might be nonexistent or 'long' |
| 341 | * (e.g. for <<). |
| 342 | */ |
| 343 | chkw(p, okt) |
| 344 | struct tnode *p; |
| 345 | { |
| 346 | register int t; |
| 347 | |
| 348 | if ((t=p->type)!=INT && t<PTR && t!=CHAR && t!=UNSIGN && t!=okt) |
| 349 | error("Illegal type of operand"); |
| 350 | return; |
| 351 | } |
| 352 | |
| 353 | /* |
| 354 | *'linearize' a type for looking up in the |
| 355 | * conversion table |
| 356 | */ |
| 357 | lintyp(t) |
| 358 | { |
| 359 | switch(t) { |
| 360 | |
| 361 | case INT: |
| 362 | case CHAR: |
| 363 | case UNSIGN: |
| 364 | return(0); |
| 365 | |
| 366 | case FLOAT: |
| 367 | case DOUBLE: |
| 368 | return(1); |
| 369 | |
| 370 | case LONG: |
| 371 | return(2); |
| 372 | |
| 373 | default: |
| 374 | return(3); |
| 375 | } |
| 376 | } |
| 377 | |
| 378 | /* |
| 379 | * Report an error. |
| 380 | */ |
| 381 | error(s, p1, p2, p3, p4, p5, p6) |
| 382 | { |
| 383 | nerror++; |
| 384 | if (filename[0]) |
| 385 | fprintf(stderr, "%s:", filename); |
| 386 | fprintf(stderr, "%d: ", line); |
| 387 | fprintf(stderr, s, p1, p2, p3, p4, p5, p6); |
| 388 | fprintf(stderr, "\n"); |
| 389 | } |
| 390 | |
| 391 | /* |
| 392 | * Generate a node in an expression tree, |
| 393 | * setting the operator, type, dimen/struct table ptrs, |
| 394 | * and the operands. |
| 395 | */ |
| 396 | struct tnode * |
| 397 | block(op, t, subs, str, p1,p2) |
| 398 | int *subs; |
| 399 | struct str *str; |
| 400 | struct tnode *p1, *p2; |
| 401 | { |
| 402 | register struct tnode *p; |
| 403 | |
| 404 | p = gblock(sizeof(*p)); |
| 405 | p->op = op; |
| 406 | p->type = t; |
| 407 | p->subsp = subs; |
| 408 | p->strp = str; |
| 409 | p->tr1 = p1; |
| 410 | if (opdope[op]&BINARY) |
| 411 | p->tr2 = p2; |
| 412 | else |
| 413 | p->tr2 = NULL; |
| 414 | return(p); |
| 415 | } |
| 416 | |
| 417 | struct tnode * |
| 418 | nblock(ads) |
| 419 | struct hshtab *ads; |
| 420 | { |
| 421 | register struct hshtab *ds; |
| 422 | |
| 423 | ds = ads; |
| 424 | return(block(NAME, ds->htype, ds->hsubsp, ds->hstrp, ds)); |
| 425 | } |
| 426 | |
| 427 | /* |
| 428 | * Generate a block for a constant |
| 429 | */ |
| 430 | struct cnode * |
| 431 | cblock(v) |
| 432 | { |
| 433 | register struct cnode *p; |
| 434 | |
| 435 | p = gblock(sizeof(*p)); |
| 436 | p->op = CON; |
| 437 | p->type = INT; |
| 438 | p->subsp = NULL; |
| 439 | p->strp = NULL; |
| 440 | p->value = v; |
| 441 | return(p); |
| 442 | } |
| 443 | |
| 444 | /* |
| 445 | * A block for a float or long constant |
| 446 | */ |
| 447 | struct fnode * |
| 448 | fblock(t, string) |
| 449 | char *string; |
| 450 | { |
| 451 | register struct fnode *p; |
| 452 | |
| 453 | p = gblock(sizeof(*p)); |
| 454 | p->op = FCON; |
| 455 | p->type = t; |
| 456 | p->subsp = NULL; |
| 457 | p->strp = NULL; |
| 458 | p->cstr = string; |
| 459 | return(p); |
| 460 | } |
| 461 | |
| 462 | /* |
| 463 | * Assign a block for use in the |
| 464 | * expression tree. |
| 465 | */ |
| 466 | char * |
| 467 | gblock(n) |
| 468 | { |
| 469 | register int *p; |
| 470 | |
| 471 | p = curbase; |
| 472 | if ((curbase =+ n) >= coremax) { |
| 473 | if (sbrk(1024) == -1) { |
| 474 | error("Out of space"); |
| 475 | exit(1); |
| 476 | } |
| 477 | coremax =+ 1024; |
| 478 | } |
| 479 | return(p); |
| 480 | } |
| 481 | |
| 482 | /* |
| 483 | * Check that a tree can be used as an lvalue. |
| 484 | */ |
| 485 | chklval(ap) |
| 486 | struct tnode *ap; |
| 487 | { |
| 488 | register struct tnode *p; |
| 489 | |
| 490 | p = ap; |
| 491 | if (p->op==FSEL) |
| 492 | p = p->tr1; |
| 493 | if (p->op!=NAME && p->op!=STAR) |
| 494 | error("Lvalue required"); |
| 495 | } |
| 496 | |
| 497 | /* |
| 498 | * reduce some forms of `constant op constant' |
| 499 | * to a constant. More of this is done in the next pass |
| 500 | * but this is used to allow constant expressions |
| 501 | * to be used in switches and array bounds. |
| 502 | */ |
| 503 | fold(op, ap1, ap2) |
| 504 | struct tnode *ap1, *ap2; |
| 505 | { |
| 506 | register struct tnode *p1; |
| 507 | register int v1, v2; |
| 508 | int unsignf; |
| 509 | |
| 510 | p1 = ap1; |
| 511 | if (p1->op!=CON) |
| 512 | return(0); |
| 513 | unsignf = p1->type==UNSIGN; |
| 514 | if (op==QUEST) { |
| 515 | if (ap2->tr1->op==CON && ap2->tr2->op==CON) { |
| 516 | p1->value = p1->value? ap2->tr1->value: ap2->tr2->value; |
| 517 | *cp++ = p1; |
| 518 | return(1); |
| 519 | } |
| 520 | return(0); |
| 521 | } |
| 522 | if (ap2) { |
| 523 | if (ap2->op!=CON) |
| 524 | return(0); |
| 525 | v2 = ap2->value; |
| 526 | unsignf |= ap2->type==UNSIGN; |
| 527 | } |
| 528 | v1 = p1->value; |
| 529 | switch (op) { |
| 530 | |
| 531 | case PLUS: |
| 532 | v1 =+ v2; |
| 533 | break; |
| 534 | |
| 535 | case MINUS: |
| 536 | v1 =- v2; |
| 537 | break; |
| 538 | |
| 539 | case TIMES: |
| 540 | v1 =* v2; |
| 541 | break; |
| 542 | |
| 543 | case DIVIDE: |
| 544 | if (v2==0) |
| 545 | goto divchk; |
| 546 | if (unsignf) { |
| 547 | v1 = (unsigned)v1 / v2; |
| 548 | break; |
| 549 | } |
| 550 | v1 =/ v2; |
| 551 | break; |
| 552 | |
| 553 | case MOD: |
| 554 | if (v2==0) |
| 555 | goto divchk; |
| 556 | if (unsignf) { |
| 557 | v1 = (unsigned)v1 % v2; |
| 558 | break; |
| 559 | } |
| 560 | v1 =% v2; |
| 561 | break; |
| 562 | |
| 563 | case AND: |
| 564 | v1 =& v2; |
| 565 | break; |
| 566 | |
| 567 | case OR: |
| 568 | v1 =| v2; |
| 569 | break; |
| 570 | |
| 571 | case EXOR: |
| 572 | v1 =^ v2; |
| 573 | break; |
| 574 | |
| 575 | case NEG: |
| 576 | v1 = - v1; |
| 577 | break; |
| 578 | |
| 579 | case COMPL: |
| 580 | v1 = ~ v1; |
| 581 | break; |
| 582 | |
| 583 | case LSHIFT: |
| 584 | v1 =<< v2; |
| 585 | break; |
| 586 | |
| 587 | case RSHIFT: |
| 588 | if (unsignf) { |
| 589 | v1 = (unsigned)v1 >> v2; |
| 590 | break; |
| 591 | } |
| 592 | v1 =>> v2; |
| 593 | break; |
| 594 | |
| 595 | case EQUAL: |
| 596 | v1 = v1==v2; |
| 597 | break; |
| 598 | |
| 599 | case NEQUAL: |
| 600 | v1 = v1!=v2; |
| 601 | break; |
| 602 | |
| 603 | case LESS: |
| 604 | v1 = v1<v2; |
| 605 | break; |
| 606 | |
| 607 | case GREAT: |
| 608 | v1 = v1>v2; |
| 609 | break; |
| 610 | |
| 611 | case LESSEQ: |
| 612 | v1 = v1<=v2; |
| 613 | break; |
| 614 | |
| 615 | case GREATEQ: |
| 616 | v1 = v1>=v2; |
| 617 | break; |
| 618 | |
| 619 | divchk: |
| 620 | error("Divide check"); |
| 621 | default: |
| 622 | return(0); |
| 623 | } |
| 624 | p1->value = v1; |
| 625 | *cp++ = p1; |
| 626 | return(1); |
| 627 | } |
| 628 | |
| 629 | /* |
| 630 | * Compile an expression expected to have constant value, |
| 631 | * for example an array bound or a case value. |
| 632 | */ |
| 633 | conexp() |
| 634 | { |
| 635 | register struct tnode *t; |
| 636 | |
| 637 | initflg++; |
| 638 | if (t = tree()) |
| 639 | if (t->op != CON) |
| 640 | error("Constant required"); |
| 641 | initflg--; |
| 642 | curbase = funcbase; |
| 643 | return(t->value); |
| 644 | } |