xref: /csrg-svn/usr.bin/pascal/src/rval.c (revision 15530)
1 /* Copyright (c) 1979 Regents of the University of California */
2 
3 static char sccsid[] = "@(#)rval.c 1.18 11/11/83";
4 
5 #include "whoami.h"
6 #include "0.h"
7 #include "tree.h"
8 #include "opcode.h"
9 #include "objfmt.h"
10 #ifdef PC
11 #   include	"pc.h"
12 #   include "pcops.h"
13 #endif PC
14 #include "tmps.h"
15 
16 extern	char *opnames[];
17 
18     /* line number of the last record comparison warning */
19 short reccompline = 0;
20     /* line number of the last non-standard set comparison */
21 short nssetline = 0;
22 
23 #ifdef PC
24     char	*relts[] =  {
25 				"_RELEQ" , "_RELNE" ,
26 				"_RELTLT" , "_RELTGT" ,
27 				"_RELTLE" , "_RELTGE"
28 			    };
29     char	*relss[] =  {
30 				"_RELEQ" , "_RELNE" ,
31 				"_RELSLT" , "_RELSGT" ,
32 				"_RELSLE" , "_RELSGE"
33 			    };
34     long	relops[] =  {
35 				P2EQ , P2NE ,
36 				P2LT , P2GT ,
37 				P2LE , P2GE
38 			    };
39     long	mathop[] =  {	P2MUL , P2PLUS , P2MINUS };
40     char	*setop[] =  {	"_MULT" , "_ADDT" , "_SUBT" };
41 #endif PC
42 /*
43  * Rvalue - an expression.
44  *
45  * Contype is the type that the caller would prefer, nand is important
46  * if constant sets or constant strings are involved, the latter
47  * because of string padding.
48  * required is a flag whether an lvalue or an rvalue is required.
49  * only VARs and structured things can have gt their lvalue this way.
50  */
51 struct nl *
52 rvalue(r, contype , required )
53 	int *r;
54 	struct nl *contype;
55 	int	required;
56 {
57 	register struct nl *p, *p1;
58 	register struct nl *q;
59 	int c, c1, *rt, w, g;
60 	char *cp, *cp1, *opname;
61 	long l;
62 	double f;
63 	extern int	flagwas;
64 	struct csetstr	csetd;
65 #	ifdef PC
66 	    struct nl	*rettype;
67 	    long	ctype;
68 	    struct nl	*tempnlp;
69 #	endif PC
70 
71 	if (r == NIL)
72 		return (NIL);
73 	if (nowexp(r))
74 		return (NIL);
75 	/*
76 	 * Pick up the name of the operation
77 	 * for future error messages.
78 	 */
79 	if (r[0] <= T_IN)
80 		opname = opnames[r[0]];
81 
82 	/*
83 	 * The root of the tree tells us what sort of expression we have.
84 	 */
85 	switch (r[0]) {
86 
87 	/*
88 	 * The constant nil
89 	 */
90 	case T_NIL:
91 #		ifdef OBJ
92 		    put(2, O_CON2, 0);
93 #		endif OBJ
94 #		ifdef PC
95 		    putleaf( P2ICON , 0 , 0 , P2PTR|P2UNDEF , 0 );
96 #		endif PC
97 		return (nl+TNIL);
98 
99 	/*
100 	 * Function call with arguments.
101 	 */
102 	case T_FCALL:
103 #	    ifdef OBJ
104 		return (funccod(r));
105 #	    endif OBJ
106 #	    ifdef PC
107 		return (pcfunccod( r ));
108 #	    endif PC
109 
110 	case T_VAR:
111 		p = lookup(r[2]);
112 		if (p == NIL || p->class == BADUSE)
113 			return (NIL);
114 		switch (p->class) {
115 		    case VAR:
116 			    /*
117 			     * If a variable is
118 			     * qualified then get
119 			     * the rvalue by a
120 			     * lvalue and an ind.
121 			     */
122 			    if (r[3] != NIL)
123 				    goto ind;
124 			    q = p->type;
125 			    if (q == NIL)
126 				    return (NIL);
127 #			    ifdef OBJ
128 				w = width(q);
129 				switch (w) {
130 				    case 8:
131 					put(2, O_RV8 | bn << 8+INDX,
132 						(int)p->value[0]);
133 					break;
134 				    case 4:
135 					put(2, O_RV4 | bn << 8+INDX,
136 						(int)p->value[0]);
137 					break;
138 				    case 2:
139 					put(2, O_RV2 | bn << 8+INDX,
140 						(int)p->value[0]);
141 					break;
142 				    case 1:
143 					put(2, O_RV1 | bn << 8+INDX,
144 						(int)p->value[0]);
145 					break;
146 				    default:
147 					put(3, O_RV | bn << 8+INDX,
148 						(int)p->value[0], w);
149 				}
150 #			   endif OBJ
151 #			   ifdef PC
152 				if ( required == RREQ ) {
153 				    putRV( p -> symbol , bn , p -> value[0] ,
154 					    p -> extra_flags , p2type( q ) );
155 				} else {
156 				    putLV( p -> symbol , bn , p -> value[0] ,
157 					    p -> extra_flags , p2type( q ) );
158 				}
159 #			   endif PC
160 			   return (q);
161 
162 		    case WITHPTR:
163 		    case REF:
164 			    /*
165 			     * A lvalue for these
166 			     * is actually what one
167 			     * might consider a rvalue.
168 			     */
169 ind:
170 			    q = lvalue(r, NOFLAGS , LREQ );
171 			    if (q == NIL)
172 				    return (NIL);
173 #			    ifdef OBJ
174 				w = width(q);
175 				switch (w) {
176 				    case 8:
177 					    put(1, O_IND8);
178 					    break;
179 				    case 4:
180 					    put(1, O_IND4);
181 					    break;
182 				    case 2:
183 					    put(1, O_IND2);
184 					    break;
185 				    case 1:
186 					    put(1, O_IND1);
187 					    break;
188 				    default:
189 					    put(2, O_IND, w);
190 				}
191 #			    endif OBJ
192 #			    ifdef PC
193 				if ( required == RREQ ) {
194 				    putop( P2UNARY P2MUL , p2type( q ) );
195 				}
196 #			    endif PC
197 			    return (q);
198 
199 		    case CONST:
200 			    if (r[3] != NIL) {
201 				error("%s is a constant and cannot be qualified", r[2]);
202 				return (NIL);
203 			    }
204 			    q = p->type;
205 			    if (q == NIL)
206 				    return (NIL);
207 			    if (q == nl+TSTR) {
208 				    /*
209 				     * Find the size of the string
210 				     * constant if needed.
211 				     */
212 				    cp = p->ptr[0];
213 cstrng:
214 				    cp1 = cp;
215 				    for (c = 0; *cp++; c++)
216 					    continue;
217 				    w = c;
218 				    if (contype != NIL && !opt('s')) {
219 					    if (width(contype) < c && classify(contype) == TSTR) {
220 						    error("Constant string too long");
221 						    return (NIL);
222 					    }
223 					    w = width(contype);
224 				    }
225 #				    ifdef OBJ
226 					put(2, O_CONG, w);
227 					putstr(cp1, w - c);
228 #				    endif OBJ
229 #				    ifdef PC
230 					putCONG( cp1 , w , required );
231 #				    endif PC
232 				    /*
233 				     * Define the string temporarily
234 				     * so later people can know its
235 				     * width.
236 				     * cleaned out by stat.
237 				     */
238 				    q = defnl(0, STR, 0, w);
239 				    q->type = q;
240 				    return (q);
241 			    }
242 			    if (q == nl+T1CHAR) {
243 #				    ifdef OBJ
244 					put(2, O_CONC, (int)p->value[0]);
245 #				    endif OBJ
246 #				    ifdef PC
247 					putleaf( P2ICON , p -> value[0] , 0
248 						, P2CHAR , 0 );
249 #				    endif PC
250 				    return (q);
251 			    }
252 			    /*
253 			     * Every other kind of constant here
254 			     */
255 			    switch (width(q)) {
256 			    case 8:
257 #ifndef DEBUG
258 #				    ifdef OBJ
259 					put(2, O_CON8, p->real);
260 #				    endif OBJ
261 #				    ifdef PC
262 					putCON8( p -> real );
263 #				    endif PC
264 #else
265 				    if (hp21mx) {
266 					    f = p->real;
267 					    conv(&f);
268 					    l = f.plong;
269 					    put(2, O_CON4, l);
270 				    } else
271 #					    ifdef OBJ
272 						put(2, O_CON8, p->real);
273 #					    endif OBJ
274 #					    ifdef PC
275 						putCON8( p -> real );
276 #					    endif PC
277 #endif
278 				    break;
279 			    case 4:
280 #				    ifdef OBJ
281 					put(2, O_CON4, p->range[0]);
282 #				    endif OBJ
283 #				    ifdef PC
284 					putleaf( P2ICON , p -> range[0] , 0
285 						, P2INT , 0 );
286 #				    endif PC
287 				    break;
288 			    case 2:
289 #				    ifdef OBJ
290 					put(2, O_CON2, (short)p->range[0]);
291 #				    endif OBJ
292 #				    ifdef PC
293 					putleaf( P2ICON , (short) p -> range[0]
294 						, 0 , P2SHORT , 0 );
295 #				    endif PC
296 				    break;
297 			    case 1:
298 #				    ifdef OBJ
299 					put(2, O_CON1, p->value[0]);
300 #				    endif OBJ
301 #				    ifdef PC
302 					putleaf( P2ICON , p -> value[0] , 0
303 						, P2CHAR , 0 );
304 #				    endif PC
305 				    break;
306 			    default:
307 				    panic("rval");
308 			    }
309 			    return (q);
310 
311 		    case FUNC:
312 		    case FFUNC:
313 			    /*
314 			     * Function call with no arguments.
315 			     */
316 			    if (r[3]) {
317 				    error("Can't qualify a function result value");
318 				    return (NIL);
319 			    }
320 #			    ifdef OBJ
321 				return (funccod((int *) r));
322 #			    endif OBJ
323 #			    ifdef PC
324 				return (pcfunccod( r ));
325 #			    endif PC
326 
327 		    case TYPE:
328 			    error("Type names (e.g. %s) allowed only in declarations", p->symbol);
329 			    return (NIL);
330 
331 		    case PROC:
332 		    case FPROC:
333 			    error("Procedure %s found where expression required", p->symbol);
334 			    return (NIL);
335 		    default:
336 			    panic("rvid");
337 		}
338 	/*
339 	 * Constant sets
340 	 */
341 	case T_CSET:
342 #		ifdef OBJ
343 		    if ( precset( r , contype , &csetd ) ) {
344 			if ( csetd.csettype == NIL ) {
345 			    return NIL;
346 			}
347 			postcset( r , &csetd );
348 		    } else {
349 			put( 2, O_PUSH, -lwidth(csetd.csettype));
350 			postcset( r , &csetd );
351 			setran( ( csetd.csettype ) -> type );
352 			put( 2, O_CON24, set.uprbp);
353 			put( 2, O_CON24, set.lwrb);
354 			put( 2, O_CTTOT,
355 				(int)(4 + csetd.singcnt + 2 * csetd.paircnt));
356 		    }
357 		    return csetd.csettype;
358 #		endif OBJ
359 #		ifdef PC
360 		    if ( precset( r , contype , &csetd ) ) {
361 			if ( csetd.csettype == NIL ) {
362 			    return NIL;
363 			}
364 			postcset( r , &csetd );
365 		    } else {
366 			putleaf( P2ICON , 0 , 0
367 				, ADDTYPE( P2FTN | P2INT , P2PTR )
368 				, "_CTTOT" );
369 			/*
370 			 *	allocate a temporary and use it
371 			 */
372 			tempnlp = tmpalloc(lwidth(csetd.csettype),
373 				csetd.csettype, NOREG);
374 			putLV( 0 , cbn , tempnlp -> value[ NL_OFFS ] ,
375 				tempnlp -> extra_flags , P2PTR|P2STRTY );
376 			setran( ( csetd.csettype ) -> type );
377 			putleaf( P2ICON , set.lwrb , 0 , P2INT , 0 );
378 			putop( P2LISTOP , P2INT );
379 			putleaf( P2ICON , set.uprbp , 0 , P2INT , 0 );
380 			putop( P2LISTOP , P2INT );
381 			postcset( r , &csetd );
382 			putop( P2CALL , P2INT );
383 		    }
384 		    return csetd.csettype;
385 #		endif PC
386 
387 	/*
388 	 * Unary plus and minus
389 	 */
390 	case T_PLUS:
391 	case T_MINUS:
392 		q = rvalue(r[2], NIL , RREQ );
393 		if (q == NIL)
394 			return (NIL);
395 		if (isnta(q, "id")) {
396 			error("Operand of %s must be integer or real, not %s", opname, nameof(q));
397 			return (NIL);
398 		}
399 		if (r[0] == T_MINUS) {
400 #		    ifdef OBJ
401 			put(1, O_NEG2 + (width(q) >> 2));
402 			return (isa(q, "d") ? q : nl+T4INT);
403 #		    endif OBJ
404 #		    ifdef PC
405 			if (isa(q, "i")) {
406 			    sconv(p2type(q), P2INT);
407 			    putop( P2UNARY P2MINUS, P2INT);
408 			    return nl+T4INT;
409 			}
410 			putop( P2UNARY P2MINUS, P2DOUBLE);
411 			return nl+TDOUBLE;
412 #		    endif PC
413 		}
414 		return (q);
415 
416 	case T_NOT:
417 		q = rvalue(r[2], NIL , RREQ );
418 		if (q == NIL)
419 			return (NIL);
420 		if (isnta(q, "b")) {
421 			error("not must operate on a Boolean, not %s", nameof(q));
422 			return (NIL);
423 		}
424 #		ifdef OBJ
425 		    put(1, O_NOT);
426 #		endif OBJ
427 #		ifdef PC
428 		    sconv(p2type(q), P2INT);
429 		    putop( P2NOT , P2INT);
430 		    sconv(P2INT, p2type(q));
431 #		endif PC
432 		return (nl+T1BOOL);
433 
434 	case T_AND:
435 	case T_OR:
436 		p = rvalue(r[2], NIL , RREQ );
437 #		ifdef PC
438 		    sconv(p2type(p),P2INT);
439 #		endif PC
440 		p1 = rvalue(r[3], NIL , RREQ );
441 #		ifdef PC
442 		    sconv(p2type(p1),P2INT);
443 #		endif PC
444 		if (p == NIL || p1 == NIL)
445 			return (NIL);
446 		if (isnta(p, "b")) {
447 			error("Left operand of %s must be Boolean, not %s", opname, nameof(p));
448 			return (NIL);
449 		}
450 		if (isnta(p1, "b")) {
451 			error("Right operand of %s must be Boolean, not %s", opname, nameof(p1));
452 			return (NIL);
453 		}
454 #		ifdef OBJ
455 		    put(1, r[0] == T_AND ? O_AND : O_OR);
456 #		endif OBJ
457 #		ifdef PC
458 			/*
459 			 * note the use of & and | rather than && and ||
460 			 * to force evaluation of all the expressions.
461 			 */
462 		    putop( r[ 0 ] == T_AND ? P2AND : P2OR , P2INT );
463 		    sconv(P2INT, p2type(p));
464 #		endif PC
465 		return (nl+T1BOOL);
466 
467 	case T_DIVD:
468 #		ifdef OBJ
469 		    p = rvalue(r[2], NIL , RREQ );
470 		    p1 = rvalue(r[3], NIL , RREQ );
471 #		endif OBJ
472 #		ifdef PC
473 			/*
474 			 *	force these to be doubles for the divide
475 			 */
476 		    p = rvalue( r[ 2 ] , NIL , RREQ );
477 		    sconv(p2type(p), P2DOUBLE);
478 		    p1 = rvalue( r[ 3 ] , NIL , RREQ );
479 		    sconv(p2type(p1), P2DOUBLE);
480 #		endif PC
481 		if (p == NIL || p1 == NIL)
482 			return (NIL);
483 		if (isnta(p, "id")) {
484 			error("Left operand of / must be integer or real, not %s", nameof(p));
485 			return (NIL);
486 		}
487 		if (isnta(p1, "id")) {
488 			error("Right operand of / must be integer or real, not %s", nameof(p1));
489 			return (NIL);
490 		}
491 #		ifdef OBJ
492 		    return gen(NIL, r[0], width(p), width(p1));
493 #		endif OBJ
494 #		ifdef PC
495 		    putop( P2DIV , P2DOUBLE );
496 		    return nl + TDOUBLE;
497 #		endif PC
498 
499 	case T_MULT:
500 	case T_ADD:
501 	case T_SUB:
502 #		ifdef OBJ
503 		    /*
504 		     * If the context hasn't told us the type
505 		     * and a constant set is present
506 		     * we need to infer the type
507 		     * before generating code.
508 		     */
509 		    if ( contype == NIL ) {
510 			    codeoff();
511 			    contype = rvalue( r[3] , NIL , RREQ );
512 			    codeon();
513 		    }
514 		    if ( contype == NIL ) {
515 			return NIL;
516 		    }
517 		    p = rvalue( r[2] , contype , RREQ );
518 		    p1 = rvalue( r[3] , p , RREQ );
519 		    if ( p == NIL || p1 == NIL )
520 			    return NIL;
521 		    if (isa(p, "id") && isa(p1, "id"))
522 			return (gen(NIL, r[0], width(p), width(p1)));
523 		    if (isa(p, "t") && isa(p1, "t")) {
524 			    if (p != p1) {
525 				    error("Set types of operands of %s must be identical", opname);
526 				    return (NIL);
527 			    }
528 			    gen(TSET, r[0], width(p), 0);
529 			    return (p);
530 		    }
531 #		endif OBJ
532 #		ifdef PC
533 			/*
534 			 * the second pass can't do
535 			 *	long op double  or  double op long
536 			 * so we have to know the type of both operands
537 			 * also, it gets tricky for sets, which are done
538 			 * by function calls.
539 			 */
540 		    codeoff();
541 		    p1 = rvalue( r[ 3 ] , contype , RREQ );
542 		    codeon();
543 		    if ( isa( p1 , "id" ) ) {
544 			p = rvalue( r[ 2 ] , contype , RREQ );
545 			if ( ( p == NIL ) || ( p1 == NIL ) ) {
546 			    return NIL;
547 			}
548 			tuac(p, p1, &rettype, &ctype);
549 			p1 = rvalue( r[ 3 ] , contype , RREQ );
550 			tuac(p1, p, &rettype, &ctype);
551 			if ( isa( p , "id" ) ) {
552 			    putop( mathop[ r[0] - T_MULT ] , ctype );
553 			    return rettype;
554 			}
555 		    }
556 		    if ( isa( p1 , "t" ) ) {
557 			putleaf( P2ICON , 0 , 0
558 			    , ADDTYPE( ADDTYPE( P2PTR | P2STRTY , P2FTN )
559 					, P2PTR )
560 			    , setop[ r[0] - T_MULT ] );
561 			if ( contype == NIL ) {
562 			    codeoff();
563 			    contype = rvalue( r[2] , p1 , LREQ );
564 			    codeon();
565 			}
566 			if ( contype == NIL ) {
567 			    return NIL;
568 			}
569 			    /*
570 			     *	allocate a temporary and use it
571 			     */
572 			tempnlp = tmpalloc(lwidth(contype), contype, NOREG);
573 			putLV( 0 , cbn , tempnlp -> value[ NL_OFFS ] ,
574 				tempnlp -> extra_flags , P2PTR|P2STRTY );
575 			p = rvalue( r[2] , contype , LREQ );
576 			if ( isa( p , "t" ) ) {
577 			    putop( P2LISTOP , P2INT );
578 			    if ( p == NIL || p1 == NIL ) {
579 				return NIL;
580 			    }
581 			    p1 = rvalue( r[3] , p , LREQ );
582 			    if ( p != p1 ) {
583 				error("Set types of operands of %s must be identical", opname);
584 				return NIL;
585 			    }
586 			    putop( P2LISTOP , P2INT );
587 			    putleaf( P2ICON , lwidth( p1 ) / sizeof( long ) , 0
588 				    , P2INT , 0 );
589 			    putop( P2LISTOP , P2INT );
590 			    putop( P2CALL , P2PTR | P2STRTY );
591 			    return p;
592 			}
593 		    }
594 		    if ( isnta( p1 , "idt" ) ) {
595 			    /*
596 			     *	find type of left operand for error message.
597 			     */
598 			p = rvalue( r[2] , contype , RREQ );
599 		    }
600 			/*
601 			 *	don't give spurious error messages.
602 			 */
603 		    if ( p == NIL || p1 == NIL ) {
604 			return NIL;
605 		    }
606 #		endif PC
607 		if (isnta(p, "idt")) {
608 			error("Left operand of %s must be integer, real or set, not %s", opname, nameof(p));
609 			return (NIL);
610 		}
611 		if (isnta(p1, "idt")) {
612 			error("Right operand of %s must be integer, real or set, not %s", opname, nameof(p1));
613 			return (NIL);
614 		}
615 		error("Cannot mix sets with integers and reals as operands of %s", opname);
616 		return (NIL);
617 
618 	case T_MOD:
619 	case T_DIV:
620 		p = rvalue(r[2], NIL , RREQ );
621 #		ifdef PC
622 		    sconv(p2type(p), P2INT);
623 #		endif PC
624 		p1 = rvalue(r[3], NIL , RREQ );
625 #		ifdef PC
626 		    sconv(p2type(p1), P2INT);
627 #		endif PC
628 		if (p == NIL || p1 == NIL)
629 			return (NIL);
630 		if (isnta(p, "i")) {
631 			error("Left operand of %s must be integer, not %s", opname, nameof(p));
632 			return (NIL);
633 		}
634 		if (isnta(p1, "i")) {
635 			error("Right operand of %s must be integer, not %s", opname, nameof(p1));
636 			return (NIL);
637 		}
638 #		ifdef OBJ
639 		    return (gen(NIL, r[0], width(p), width(p1)));
640 #		endif OBJ
641 #		ifdef PC
642 		    putop( r[ 0 ] == T_DIV ? P2DIV : P2MOD , P2INT );
643 		    return ( nl + T4INT );
644 #		endif PC
645 
646 	case T_EQ:
647 	case T_NE:
648 	case T_LT:
649 	case T_GT:
650 	case T_LE:
651 	case T_GE:
652 		/*
653 		 * Since there can be no, a priori, knowledge
654 		 * of the context type should a constant string
655 		 * or set arise, we must poke around to find such
656 		 * a type if possible.  Since constant strings can
657 		 * always masquerade as identifiers, this is always
658 		 * necessary.
659 		 */
660 		codeoff();
661 		p1 = rvalue(r[3], NIL , RREQ );
662 		codeon();
663 		if (p1 == NIL)
664 			return (NIL);
665 		contype = p1;
666 #		ifdef OBJ
667 		    if (p1->class == STR) {
668 			    /*
669 			     * For constant strings we want
670 			     * the longest type so as to be
671 			     * able to do padding (more importantly
672 			     * avoiding truncation). For clarity,
673 			     * we get this length here.
674 			     */
675 			    codeoff();
676 			    p = rvalue(r[2], NIL , RREQ );
677 			    codeon();
678 			    if (p == NIL)
679 				    return (NIL);
680 			    if (width(p) > width(p1))
681 				    contype = p;
682 		    }
683 		    /*
684 		     * Now we generate code for
685 		     * the operands of the relational
686 		     * operation.
687 		     */
688 		    p = rvalue(r[2], contype , RREQ );
689 		    if (p == NIL)
690 			    return (NIL);
691 		    p1 = rvalue(r[3], p , RREQ );
692 		    if (p1 == NIL)
693 			    return (NIL);
694 #		endif OBJ
695 #		ifdef PC
696 		    c1 = classify( p1 );
697 		    if ( c1 == TSET || c1 == TSTR || c1 == TREC ) {
698 			putleaf( P2ICON , 0 , 0
699 				, ADDTYPE( P2FTN | P2INT , P2PTR )
700 				, c1 == TSET  ? relts[ r[0] - T_EQ ]
701 					      : relss[ r[0] - T_EQ ] );
702 			    /*
703 			     *	for [] and strings, comparisons are done on
704 			     *	the maximum width of the two sides.
705 			     *	for other sets, we have to ask the left side
706 			     *	what type it is based on the type of the right.
707 			     *	(this matters for intsets).
708 			     */
709 			if ( c1 == TSTR ) {
710 			    codeoff();
711 			    p = rvalue( r[ 2 ] , NIL , LREQ );
712 			    codeon();
713 			    if ( p == NIL ) {
714 				return NIL;
715 			    }
716 			    if ( lwidth( p ) > lwidth( p1 ) ) {
717 				contype = p;
718 			    }
719 			} else if ( c1 == TSET ) {
720 			    codeoff();
721 			    p = rvalue( r[ 2 ] , contype , LREQ );
722 			    codeon();
723 			    if ( p == NIL ) {
724 				return NIL;
725 			    }
726 			    contype = p;
727 			}
728 			    /*
729 			     *	put out the width of the comparison.
730 			     */
731 			putleaf( P2ICON , lwidth( contype ) , 0 , P2INT , 0 );
732 			    /*
733 			     *	and the left hand side,
734 			     *	for sets, strings, records
735 			     */
736 			p = rvalue( r[ 2 ] , contype , LREQ );
737 			if ( p == NIL ) {
738 			    return NIL;
739 			}
740 			putop( P2LISTOP , P2INT );
741 			p1 = rvalue( r[ 3 ] , p , LREQ );
742 			if ( p1 == NIL ) {
743 			    return NIL;
744 			}
745 			putop( P2LISTOP , P2INT );
746 			putop( P2CALL , P2INT );
747 		    } else {
748 			    /*
749 			     *	the easy (scalar or error) case
750 			     */
751 			p = rvalue( r[ 2 ] , contype , RREQ );
752 			if ( p == NIL ) {
753 			    return NIL;
754 			}
755 			    /*
756 			     * since the second pass can't do
757 			     *	long op double  or  double op long
758 			     * we may have to do some coercing.
759 			     */
760 			tuac(p, p1, &rettype, &ctype);
761 			p1 = rvalue( r[ 3 ] , p , RREQ );
762 			if ( p1 == NIL ) {
763 			    return NIL;
764 			}
765 			tuac(p1, p, &rettype, &ctype);
766 			putop( relops[ r[0] - T_EQ ] , P2INT );
767 			sconv(P2INT, P2CHAR);
768 		    }
769 #		endif PC
770 		c = classify(p);
771 		c1 = classify(p1);
772 		if (nocomp(c) || nocomp(c1))
773 			return (NIL);
774 		g = NIL;
775 		switch (c) {
776 			case TBOOL:
777 			case TCHAR:
778 				if (c != c1)
779 					goto clash;
780 				break;
781 			case TINT:
782 			case TDOUBLE:
783 				if (c1 != TINT && c1 != TDOUBLE)
784 					goto clash;
785 				break;
786 			case TSCAL:
787 				if (c1 != TSCAL)
788 					goto clash;
789 				if (scalar(p) != scalar(p1))
790 					goto nonident;
791 				break;
792 			case TSET:
793 				if (c1 != TSET)
794 					goto clash;
795 				if ( opt( 's' ) &&
796 				    ( ( r[0] == T_LT ) || ( r[0] == T_GT ) ) &&
797 				    ( line != nssetline ) ) {
798 				    nssetline = line;
799 				    standard();
800 				    error("%s comparison on sets is non-standard" , opname );
801 				}
802 				if (p != p1)
803 					goto nonident;
804 				g = TSET;
805 				break;
806 			case TREC:
807 				if ( c1 != TREC ) {
808 				    goto clash;
809 				}
810 				if ( p != p1 ) {
811 				    goto nonident;
812 				}
813 				if (r[0] != T_EQ && r[0] != T_NE) {
814 					error("%s not allowed on records - only allow = and <>" , opname );
815 					return (NIL);
816 				}
817 				g = TREC;
818 				break;
819 			case TPTR:
820 			case TNIL:
821 				if (c1 != TPTR && c1 != TNIL)
822 					goto clash;
823 				if (r[0] != T_EQ && r[0] != T_NE) {
824 					error("%s not allowed on pointers - only allow = and <>" , opname );
825 					return (NIL);
826 				}
827 				if (p != nl+TNIL && p1 != nl+TNIL && p != p1)
828 					goto nonident;
829 				break;
830 			case TSTR:
831 				if (c1 != TSTR)
832 					goto clash;
833 				if (width(p) != width(p1)) {
834 					error("Strings not same length in %s comparison", opname);
835 					return (NIL);
836 				}
837 				g = TSTR;
838 				break;
839 			default:
840 				panic("rval2");
841 		}
842 #		ifdef OBJ
843 		    return (gen(g, r[0], width(p), width(p1)));
844 #		endif OBJ
845 #		ifdef PC
846 		    return nl + TBOOL;
847 #		endif PC
848 clash:
849 		error("%ss and %ss cannot be compared - operator was %s", clnames[c], clnames[c1], opname);
850 		return (NIL);
851 nonident:
852 		error("%s types must be identical in comparisons - operator was %s", clnames[c1], opname);
853 		return (NIL);
854 
855 	case T_IN:
856 	    rt = r[3];
857 #	    ifdef OBJ
858 		if (rt != NIL && rt[0] == T_CSET) {
859 			precset( rt , NIL , &csetd );
860 			p1 = csetd.csettype;
861 			if (p1 == NIL)
862 			    return NIL;
863 			postcset( rt, &csetd);
864 		    } else {
865 			p1 = stkrval(r[3], NIL , RREQ );
866 			rt = NIL;
867 		    }
868 #		endif OBJ
869 #		ifdef PC
870 		    if (rt != NIL && rt[0] == T_CSET) {
871 			if ( precset( rt , NIL , &csetd ) ) {
872 			    putleaf( P2ICON , 0 , 0
873 				    , ADDTYPE( P2FTN | P2INT , P2PTR )
874 				    , "_IN" );
875 			} else {
876 			    putleaf( P2ICON , 0 , 0
877 				    , ADDTYPE( P2FTN | P2INT , P2PTR )
878 				    , "_INCT" );
879 			}
880 			p1 = csetd.csettype;
881 			if (p1 == NIL)
882 			    return NIL;
883 		    } else {
884 			putleaf( P2ICON , 0 , 0
885 				, ADDTYPE( P2FTN | P2INT , P2PTR )
886 				, "_IN" );
887 			codeoff();
888 			p1 = rvalue(r[3], NIL , LREQ );
889 			codeon();
890 		    }
891 #		endif PC
892 		p = stkrval(r[2], NIL , RREQ );
893 		if (p == NIL || p1 == NIL)
894 			return (NIL);
895 		if (p1->class != SET) {
896 			error("Right operand of 'in' must be a set, not %s", nameof(p1));
897 			return (NIL);
898 		}
899 		if (incompat(p, p1->type, r[2])) {
900 			cerror("Index type clashed with set component type for 'in'");
901 			return (NIL);
902 		}
903 		setran(p1->type);
904 #		ifdef OBJ
905 		    if (rt == NIL || csetd.comptime)
906 			    put(4, O_IN, width(p1), set.lwrb, set.uprbp);
907 		    else
908 			    put(2, O_INCT,
909 				(int)(3 + csetd.singcnt + 2*csetd.paircnt));
910 #		endif OBJ
911 #		ifdef PC
912 		    if ( rt == NIL || rt[0] != T_CSET ) {
913 			putleaf( P2ICON , set.lwrb , 0 , P2INT , 0 );
914 			putop( P2LISTOP , P2INT );
915 			putleaf( P2ICON , set.uprbp , 0 , P2INT , 0 );
916 			putop( P2LISTOP , P2INT );
917 			p1 = rvalue( r[3] , NIL , LREQ );
918 			if ( p1 == NIL ) {
919 			    return NIL;
920 			}
921 			putop( P2LISTOP , P2INT );
922 		    } else if ( csetd.comptime ) {
923 			putleaf( P2ICON , set.lwrb , 0 , P2INT , 0 );
924 			putop( P2LISTOP , P2INT );
925 			putleaf( P2ICON , set.uprbp , 0 , P2INT , 0 );
926 			putop( P2LISTOP , P2INT );
927 			postcset( r[3] , &csetd );
928 			putop( P2LISTOP , P2INT );
929 		    } else {
930 			postcset( r[3] , &csetd );
931 		    }
932 		    putop( P2CALL , P2INT );
933 		    sconv(P2INT, P2CHAR);
934 #		endif PC
935 		return (nl+T1BOOL);
936 	default:
937 		if (r[2] == NIL)
938 			return (NIL);
939 		switch (r[0]) {
940 		default:
941 			panic("rval3");
942 
943 
944 		/*
945 		 * An octal number
946 		 */
947 		case T_BINT:
948 			f = a8tol(r[2]);
949 			goto conint;
950 
951 		/*
952 		 * A decimal number
953 		 */
954 		case T_INT:
955 			f = atof(r[2]);
956 conint:
957 			if (f > MAXINT || f < MININT) {
958 				error("Constant too large for this implementation");
959 				return (NIL);
960 			}
961 			l = f;
962 #			ifdef OBJ
963 			    if (bytes(l, l) <= 2) {
964 				    put(2, O_CON2, ( short ) l);
965 				    return (nl+T2INT);
966 			    }
967 			    put(2, O_CON4, l);
968 			    return (nl+T4INT);
969 #			endif OBJ
970 #			ifdef PC
971 			    switch (bytes(l, l)) {
972 				case 1:
973 				    putleaf(P2ICON, l, 0, P2CHAR, 0);
974 				    return nl+T1INT;
975 				case 2:
976 				    putleaf(P2ICON, l, 0, P2SHORT, 0);
977 				    return nl+T2INT;
978 				case 4:
979 				    putleaf(P2ICON, l, 0, P2INT, 0);
980 				    return nl+T4INT;
981 			    }
982 #			endif PC
983 
984 		/*
985 		 * A floating point number
986 		 */
987 		case T_FINT:
988 #			ifdef OBJ
989 			    put(2, O_CON8, atof(r[2]));
990 #			endif OBJ
991 #			ifdef PC
992 			    putCON8( atof( r[2] ) );
993 #			endif PC
994 			return (nl+TDOUBLE);
995 
996 		/*
997 		 * Constant strings.  Note that constant characters
998 		 * are constant strings of length one; there is
999 		 * no constant string of length one.
1000 		 */
1001 		case T_STRNG:
1002 			cp = r[2];
1003 			if (cp[1] == 0) {
1004 #				ifdef OBJ
1005 				    put(2, O_CONC, cp[0]);
1006 #				endif OBJ
1007 #				ifdef PC
1008 				    putleaf( P2ICON , cp[0] , 0 , P2CHAR , 0 );
1009 #				endif PC
1010 				return (nl+T1CHAR);
1011 			}
1012 			goto cstrng;
1013 		}
1014 
1015 	}
1016 }
1017 
1018 /*
1019  * Can a class appear
1020  * in a comparison ?
1021  */
1022 nocomp(c)
1023 	int c;
1024 {
1025 
1026 	switch (c) {
1027 		case TREC:
1028 			if ( line != reccompline ) {
1029 			    reccompline = line;
1030 			    warning();
1031 			    if ( opt( 's' ) ) {
1032 				standard();
1033 			    }
1034 			    error("record comparison is non-standard");
1035 			}
1036 			break;
1037 		case TFILE:
1038 		case TARY:
1039 			error("%ss may not participate in comparisons", clnames[c]);
1040 			return (1);
1041 	}
1042 	return (NIL);
1043 }
1044 
1045     /*
1046      *	this is sort of like gconst, except it works on expression trees
1047      *	rather than declaration trees, and doesn't give error messages for
1048      *	non-constant things.
1049      *	as a side effect this fills in the con structure that gconst uses.
1050      *	this returns TRUE or FALSE.
1051      */
1052 constval(r)
1053 	register int *r;
1054 {
1055 	register struct nl *np;
1056 	register *cn;
1057 	char *cp;
1058 	int negd, sgnd;
1059 	long ci;
1060 
1061 	con.ctype = NIL;
1062 	cn = r;
1063 	negd = sgnd = 0;
1064 loop:
1065 	    /*
1066 	     *	cn[2] is nil if error recovery generated a T_STRNG
1067 	     */
1068 	if (cn == NIL || cn[2] == NIL)
1069 		return FALSE;
1070 	switch (cn[0]) {
1071 		default:
1072 			return FALSE;
1073 		case T_MINUS:
1074 			negd = 1 - negd;
1075 			/* and fall through */
1076 		case T_PLUS:
1077 			sgnd++;
1078 			cn = cn[2];
1079 			goto loop;
1080 		case T_NIL:
1081 			con.cpval = NIL;
1082 			con.cival = 0;
1083 			con.crval = con.cival;
1084 			con.ctype = nl + TNIL;
1085 			break;
1086 		case T_VAR:
1087 			np = lookup(cn[2]);
1088 			if (np == NIL || np->class != CONST) {
1089 				return FALSE;
1090 			}
1091 			if ( cn[3] != NIL ) {
1092 				return FALSE;
1093 			}
1094 			con.ctype = np->type;
1095 			switch (classify(np->type)) {
1096 				case TINT:
1097 					con.crval = np->range[0];
1098 					break;
1099 				case TDOUBLE:
1100 					con.crval = np->real;
1101 					break;
1102 				case TBOOL:
1103 				case TCHAR:
1104 				case TSCAL:
1105 					con.cival = np->value[0];
1106 					con.crval = con.cival;
1107 					break;
1108 				case TSTR:
1109 					con.cpval = np->ptr[0];
1110 					break;
1111 				default:
1112 					con.ctype = NIL;
1113 					return FALSE;
1114 			}
1115 			break;
1116 		case T_BINT:
1117 			con.crval = a8tol(cn[2]);
1118 			goto restcon;
1119 		case T_INT:
1120 			con.crval = atof(cn[2]);
1121 			if (con.crval > MAXINT || con.crval < MININT) {
1122 				derror("Constant too large for this implementation");
1123 				con.crval = 0;
1124 			}
1125 restcon:
1126 			ci = con.crval;
1127 #ifndef PI0
1128 			if (bytes(ci, ci) <= 2)
1129 				con.ctype = nl+T2INT;
1130 			else
1131 #endif
1132 				con.ctype = nl+T4INT;
1133 			break;
1134 		case T_FINT:
1135 			con.ctype = nl+TDOUBLE;
1136 			con.crval = atof(cn[2]);
1137 			break;
1138 		case T_STRNG:
1139 			cp = cn[2];
1140 			if (cp[1] == 0) {
1141 				con.ctype = nl+T1CHAR;
1142 				con.cival = cp[0];
1143 				con.crval = con.cival;
1144 				break;
1145 			}
1146 			con.ctype = nl+TSTR;
1147 			con.cpval = cp;
1148 			break;
1149 	}
1150 	if (sgnd) {
1151 		if (isnta(con.ctype, "id")) {
1152 			derror("%s constants cannot be signed", nameof(con.ctype));
1153 			return FALSE;
1154 		} else if (negd)
1155 			con.crval = -con.crval;
1156 	}
1157 	return TRUE;
1158 }
1159