xref: /csrg-svn/usr.bin/pascal/src/rval.c (revision 10364)
1 /* Copyright (c) 1979 Regents of the University of California */
2 
3 static char sccsid[] = "@(#)rval.c 1.14 01/17/83";
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 
15 extern	char *opnames[];
16 
17     /* line number of the last record comparison warning */
18 short reccompline = 0;
19     /* line number of the last non-standard set comparison */
20 short nssetline = 0;
21 
22 #ifdef PC
23     char	*relts[] =  {
24 				"_RELEQ" , "_RELNE" ,
25 				"_RELTLT" , "_RELTGT" ,
26 				"_RELTLE" , "_RELTGE"
27 			    };
28     char	*relss[] =  {
29 				"_RELEQ" , "_RELNE" ,
30 				"_RELSLT" , "_RELSGT" ,
31 				"_RELSLE" , "_RELSGE"
32 			    };
33     long	relops[] =  {
34 				P2EQ , P2NE ,
35 				P2LT , P2GT ,
36 				P2LE , P2GE
37 			    };
38     long	mathop[] =  {	P2MUL , P2PLUS , P2MINUS };
39     char	*setop[] =  {	"_MULT" , "_ADDT" , "_SUBT" };
40 #endif PC
41 /*
42  * Rvalue - an expression.
43  *
44  * Contype is the type that the caller would prefer, nand is important
45  * if constant sets or constant strings are involved, the latter
46  * because of string padding.
47  * required is a flag whether an lvalue or an rvalue is required.
48  * only VARs and structured things can have gt their lvalue this way.
49  */
50 struct nl *
51 rvalue(r, contype , required )
52 	int *r;
53 	struct nl *contype;
54 	int	required;
55 {
56 	register struct nl *p, *p1;
57 	register struct nl *q;
58 	int c, c1, *rt, w, g;
59 	char *cp, *cp1, *opname;
60 	long l;
61 	double f;
62 	extern int	flagwas;
63 	struct csetstr	csetd;
64 #	ifdef PC
65 	    struct nl	*rettype;
66 	    long	ctype;
67 	    struct nl	*tempnlp;
68 #	endif PC
69 
70 	if (r == NIL)
71 		return (NIL);
72 	if (nowexp(r))
73 		return (NIL);
74 	/*
75 	 * Pick up the name of the operation
76 	 * for future error messages.
77 	 */
78 	if (r[0] <= T_IN)
79 		opname = opnames[r[0]];
80 
81 	/*
82 	 * The root of the tree tells us what sort of expression we have.
83 	 */
84 	switch (r[0]) {
85 
86 	/*
87 	 * The constant nil
88 	 */
89 	case T_NIL:
90 #		ifdef OBJ
91 		    put(2, O_CON2, 0);
92 #		endif OBJ
93 #		ifdef PC
94 		    putleaf( P2ICON , 0 , 0 , P2PTR|P2UNDEF , 0 );
95 #		endif PC
96 		return (nl+TNIL);
97 
98 	/*
99 	 * Function call with arguments.
100 	 */
101 	case T_FCALL:
102 #	    ifdef OBJ
103 		return (funccod(r));
104 #	    endif OBJ
105 #	    ifdef PC
106 		return (pcfunccod( r ));
107 #	    endif PC
108 
109 	case T_VAR:
110 		p = lookup(r[2]);
111 		if (p == NIL || p->class == BADUSE)
112 			return (NIL);
113 		switch (p->class) {
114 		    case VAR:
115 			    /*
116 			     * If a variable is
117 			     * qualified then get
118 			     * the rvalue by a
119 			     * lvalue and an ind.
120 			     */
121 			    if (r[3] != NIL)
122 				    goto ind;
123 			    q = p->type;
124 			    if (q == NIL)
125 				    return (NIL);
126 #			    ifdef OBJ
127 				w = width(q);
128 				switch (w) {
129 				    case 8:
130 					put(2, O_RV8 | bn << 8+INDX,
131 						(int)p->value[0]);
132 					break;
133 				    case 4:
134 					put(2, O_RV4 | bn << 8+INDX,
135 						(int)p->value[0]);
136 					break;
137 				    case 2:
138 					put(2, O_RV2 | bn << 8+INDX,
139 						(int)p->value[0]);
140 					break;
141 				    case 1:
142 					put(2, O_RV1 | bn << 8+INDX,
143 						(int)p->value[0]);
144 					break;
145 				    default:
146 					put(3, O_RV | bn << 8+INDX,
147 						(int)p->value[0], w);
148 				}
149 #			   endif OBJ
150 #			   ifdef PC
151 				if ( required == RREQ ) {
152 				    putRV( p -> symbol , bn , p -> value[0] ,
153 					    p -> extra_flags , p2type( q ) );
154 				} else {
155 				    putLV( p -> symbol , bn , p -> value[0] ,
156 					    p -> extra_flags , p2type( q ) );
157 				}
158 #			   endif PC
159 			   return (q);
160 
161 		    case WITHPTR:
162 		    case REF:
163 			    /*
164 			     * A lvalue for these
165 			     * is actually what one
166 			     * might consider a rvalue.
167 			     */
168 ind:
169 			    q = lvalue(r, NOFLAGS , LREQ );
170 			    if (q == NIL)
171 				    return (NIL);
172 #			    ifdef OBJ
173 				w = width(q);
174 				switch (w) {
175 				    case 8:
176 					    put(1, O_IND8);
177 					    break;
178 				    case 4:
179 					    put(1, O_IND4);
180 					    break;
181 				    case 2:
182 					    put(1, O_IND2);
183 					    break;
184 				    case 1:
185 					    put(1, O_IND1);
186 					    break;
187 				    default:
188 					    put(2, O_IND, w);
189 				}
190 #			    endif OBJ
191 #			    ifdef PC
192 				if ( required == RREQ ) {
193 				    putop( P2UNARY P2MUL , p2type( q ) );
194 				}
195 #			    endif PC
196 			    return (q);
197 
198 		    case CONST:
199 			    if (r[3] != NIL) {
200 				error("%s is a constant and cannot be qualified", r[2]);
201 				return (NIL);
202 			    }
203 			    q = p->type;
204 			    if (q == NIL)
205 				    return (NIL);
206 			    if (q == nl+TSTR) {
207 				    /*
208 				     * Find the size of the string
209 				     * constant if needed.
210 				     */
211 				    cp = p->ptr[0];
212 cstrng:
213 				    cp1 = cp;
214 				    for (c = 0; *cp++; c++)
215 					    continue;
216 				    w = c;
217 				    if (contype != NIL && !opt('s')) {
218 					    if (width(contype) < c && classify(contype) == TSTR) {
219 						    error("Constant string too long");
220 						    return (NIL);
221 					    }
222 					    w = width(contype);
223 				    }
224 #				    ifdef OBJ
225 					put(2, O_CONG, w);
226 					putstr(cp1, w - c);
227 #				    endif OBJ
228 #				    ifdef PC
229 					putCONG( cp1 , w , required );
230 #				    endif PC
231 				    /*
232 				     * Define the string temporarily
233 				     * so later people can know its
234 				     * width.
235 				     * cleaned out by stat.
236 				     */
237 				    q = defnl(0, STR, 0, w);
238 				    q->type = q;
239 				    return (q);
240 			    }
241 			    if (q == nl+T1CHAR) {
242 #				    ifdef OBJ
243 					put(2, O_CONC, (int)p->value[0]);
244 #				    endif OBJ
245 #				    ifdef PC
246 					putleaf( P2ICON , p -> value[0] , 0
247 						, P2CHAR , 0 );
248 #				    endif PC
249 				    return (q);
250 			    }
251 			    /*
252 			     * Every other kind of constant here
253 			     */
254 			    switch (width(q)) {
255 			    case 8:
256 #ifndef DEBUG
257 #				    ifdef OBJ
258 					put(2, O_CON8, p->real);
259 #				    endif OBJ
260 #				    ifdef PC
261 					putCON8( p -> real );
262 #				    endif PC
263 #else
264 				    if (hp21mx) {
265 					    f = p->real;
266 					    conv(&f);
267 					    l = f.plong;
268 					    put(2, O_CON4, l);
269 				    } else
270 #					    ifdef OBJ
271 						put(2, O_CON8, p->real);
272 #					    endif OBJ
273 #					    ifdef PC
274 						putCON8( p -> real );
275 #					    endif PC
276 #endif
277 				    break;
278 			    case 4:
279 #				    ifdef OBJ
280 					put(2, O_CON4, p->range[0]);
281 #				    endif OBJ
282 #				    ifdef PC
283 					putleaf( P2ICON , p -> range[0] , 0
284 						, P2INT , 0 );
285 #				    endif PC
286 				    break;
287 			    case 2:
288 #				    ifdef OBJ
289 					put(2, O_CON2, (short)p->range[0]);
290 #				    endif OBJ
291 #				    ifdef PC
292 					putleaf( P2ICON , (short) p -> range[0]
293 						, 0 , P2SHORT , 0 );
294 #				    endif PC
295 				    break;
296 			    case 1:
297 #				    ifdef OBJ
298 					put(2, O_CON1, p->value[0]);
299 #				    endif OBJ
300 #				    ifdef PC
301 					putleaf( P2ICON , p -> value[0] , 0
302 						, P2CHAR , 0 );
303 #				    endif PC
304 				    break;
305 			    default:
306 				    panic("rval");
307 			    }
308 			    return (q);
309 
310 		    case FUNC:
311 		    case FFUNC:
312 			    /*
313 			     * Function call with no arguments.
314 			     */
315 			    if (r[3]) {
316 				    error("Can't qualify a function result value");
317 				    return (NIL);
318 			    }
319 #			    ifdef OBJ
320 				return (funccod((int *) r));
321 #			    endif OBJ
322 #			    ifdef PC
323 				return (pcfunccod( r ));
324 #			    endif PC
325 
326 		    case TYPE:
327 			    error("Type names (e.g. %s) allowed only in declarations", p->symbol);
328 			    return (NIL);
329 
330 		    case PROC:
331 		    case FPROC:
332 			    error("Procedure %s found where expression required", p->symbol);
333 			    return (NIL);
334 		    default:
335 			    panic("rvid");
336 		}
337 	/*
338 	 * Constant sets
339 	 */
340 	case T_CSET:
341 #		ifdef OBJ
342 		    if ( precset( r , contype , &csetd ) ) {
343 			if ( csetd.csettype == NIL ) {
344 			    return NIL;
345 			}
346 			postcset( r , &csetd );
347 		    } else {
348 			put( 2, O_PUSH, -lwidth(csetd.csettype));
349 			postcset( r , &csetd );
350 			setran( ( csetd.csettype ) -> type );
351 			put( 2, O_CON24, set.uprbp);
352 			put( 2, O_CON24, set.lwrb);
353 			put( 2, O_CTTOT,
354 				(int)(4 + csetd.singcnt + 2 * csetd.paircnt));
355 		    }
356 		    return csetd.csettype;
357 #		endif OBJ
358 #		ifdef PC
359 		    if ( precset( r , contype , &csetd ) ) {
360 			if ( csetd.csettype == NIL ) {
361 			    return NIL;
362 			}
363 			postcset( r , &csetd );
364 		    } else {
365 			putleaf( P2ICON , 0 , 0
366 				, ADDTYPE( P2FTN | P2INT , P2PTR )
367 				, "_CTTOT" );
368 			/*
369 			 *	allocate a temporary and use it
370 			 */
371 			tempnlp = tmpalloc(lwidth(csetd.csettype),
372 				csetd.csettype, NOREG);
373 			putLV( 0 , cbn , tempnlp -> value[ NL_OFFS ] ,
374 				tempnlp -> extra_flags , P2PTR|P2STRTY );
375 			setran( ( csetd.csettype ) -> type );
376 			putleaf( P2ICON , set.lwrb , 0 , P2INT , 0 );
377 			putop( P2LISTOP , P2INT );
378 			putleaf( P2ICON , set.uprbp , 0 , P2INT , 0 );
379 			putop( P2LISTOP , P2INT );
380 			postcset( r , &csetd );
381 			putop( P2CALL , P2INT );
382 		    }
383 		    return csetd.csettype;
384 #		endif PC
385 
386 	/*
387 	 * Unary plus and minus
388 	 */
389 	case T_PLUS:
390 	case T_MINUS:
391 		q = rvalue(r[2], NIL , RREQ );
392 		if (q == NIL)
393 			return (NIL);
394 		if (isnta(q, "id")) {
395 			error("Operand of %s must be integer or real, not %s", opname, nameof(q));
396 			return (NIL);
397 		}
398 		if (r[0] == T_MINUS) {
399 #		    ifdef OBJ
400 			put(1, O_NEG2 + (width(q) >> 2));
401 #		    endif OBJ
402 #		    ifdef PC
403 			sconv(p2type(q), P2INT);
404 			putop( P2UNARY P2MINUS , P2INT );
405 #		    endif PC
406 		    return (isa(q, "d") ? q : nl+T4INT);
407 		}
408 		return (q);
409 
410 	case T_NOT:
411 		q = rvalue(r[2], NIL , RREQ );
412 		if (q == NIL)
413 			return (NIL);
414 		if (isnta(q, "b")) {
415 			error("not must operate on a Boolean, not %s", nameof(q));
416 			return (NIL);
417 		}
418 #		ifdef OBJ
419 		    put(1, O_NOT);
420 #		endif OBJ
421 #		ifdef PC
422 		    sconv(p2type(q), P2INT);
423 		    putop( P2NOT , P2INT);
424 		    sconv(P2INT, p2type(q));
425 #		endif PC
426 		return (nl+T1BOOL);
427 
428 	case T_AND:
429 	case T_OR:
430 		p = rvalue(r[2], NIL , RREQ );
431 #		ifdef PC
432 		    sconv(p2type(p),P2INT);
433 #		endif PC
434 		p1 = rvalue(r[3], NIL , RREQ );
435 #		ifdef PC
436 		    sconv(p2type(p1),P2INT);
437 #		endif PC
438 		if (p == NIL || p1 == NIL)
439 			return (NIL);
440 		if (isnta(p, "b")) {
441 			error("Left operand of %s must be Boolean, not %s", opname, nameof(p));
442 			return (NIL);
443 		}
444 		if (isnta(p1, "b")) {
445 			error("Right operand of %s must be Boolean, not %s", opname, nameof(p1));
446 			return (NIL);
447 		}
448 #		ifdef OBJ
449 		    put(1, r[0] == T_AND ? O_AND : O_OR);
450 #		endif OBJ
451 #		ifdef PC
452 			/*
453 			 * note the use of & and | rather than && and ||
454 			 * to force evaluation of all the expressions.
455 			 */
456 		    putop( r[ 0 ] == T_AND ? P2AND : P2OR , P2INT );
457 		    sconv(P2INT, p2type(p));
458 #		endif PC
459 		return (nl+T1BOOL);
460 
461 	case T_DIVD:
462 #		ifdef OBJ
463 		    p = rvalue(r[2], NIL , RREQ );
464 		    p1 = rvalue(r[3], NIL , RREQ );
465 #		endif OBJ
466 #		ifdef PC
467 			/*
468 			 *	force these to be doubles for the divide
469 			 */
470 		    p = rvalue( r[ 2 ] , NIL , RREQ );
471 		    sconv(p2type(p), P2DOUBLE);
472 		    p1 = rvalue( r[ 3 ] , NIL , RREQ );
473 		    sconv(p2type(p1), P2DOUBLE);
474 #		endif PC
475 		if (p == NIL || p1 == NIL)
476 			return (NIL);
477 		if (isnta(p, "id")) {
478 			error("Left operand of / must be integer or real, not %s", nameof(p));
479 			return (NIL);
480 		}
481 		if (isnta(p1, "id")) {
482 			error("Right operand of / must be integer or real, not %s", nameof(p1));
483 			return (NIL);
484 		}
485 #		ifdef OBJ
486 		    return gen(NIL, r[0], width(p), width(p1));
487 #		endif OBJ
488 #		ifdef PC
489 		    putop( P2DIV , P2DOUBLE );
490 		    return nl + TDOUBLE;
491 #		endif PC
492 
493 	case T_MULT:
494 	case T_ADD:
495 	case T_SUB:
496 #		ifdef OBJ
497 		    /*
498 		     * If the context hasn't told us the type
499 		     * and a constant set is present
500 		     * we need to infer the type
501 		     * before generating code.
502 		     */
503 		    if ( contype == NIL ) {
504 			    codeoff();
505 			    contype = rvalue( r[3] , NIL , RREQ );
506 			    codeon();
507 			    if ( contype == lookup( intset ) -> type ) {
508 				codeoff();
509 				contype = rvalue( r[2] , NIL , RREQ );
510 				codeon();
511 			    }
512 		    }
513 		    if ( contype == NIL ) {
514 			return NIL;
515 		    }
516 		    p = rvalue( r[2] , contype , RREQ );
517 		    p1 = rvalue( r[3] , p , RREQ );
518 		    if ( p == NIL || p1 == NIL )
519 			    return NIL;
520 		    if (isa(p, "id") && isa(p1, "id"))
521 			return (gen(NIL, r[0], width(p), width(p1)));
522 		    if (isa(p, "t") && isa(p1, "t")) {
523 			    if (p != p1) {
524 				    error("Set types of operands of %s must be identical", opname);
525 				    return (NIL);
526 			    }
527 			    gen(TSET, r[0], width(p), 0);
528 			    return (p);
529 		    }
530 #		endif OBJ
531 #		ifdef PC
532 			/*
533 			 * the second pass can't do
534 			 *	long op double  or  double op long
535 			 * so we have to know the type of both operands
536 			 * also, it gets tricky for sets, which are done
537 			 * by function calls.
538 			 */
539 		    codeoff();
540 		    p1 = rvalue( r[ 3 ] , contype , RREQ );
541 		    codeon();
542 		    if ( isa( p1 , "id" ) ) {
543 			p = rvalue( r[ 2 ] , contype , RREQ );
544 			if ( ( p == NIL ) || ( p1 == NIL ) ) {
545 			    return NIL;
546 			}
547 			tuac(p, p1, &rettype, &ctype);
548 			p1 = rvalue( r[ 3 ] , contype , RREQ );
549 			tuac(p1, p, &rettype, &ctype);
550 			if ( isa( p , "id" ) ) {
551 			    putop( mathop[ r[0] - T_MULT ] , ctype );
552 			    return rettype;
553 			}
554 		    }
555 		    if ( isa( p1 , "t" ) ) {
556 			putleaf( P2ICON , 0 , 0
557 			    , ADDTYPE( ADDTYPE( P2PTR | P2STRTY , P2FTN )
558 					, P2PTR )
559 			    , setop[ r[0] - T_MULT ] );
560 			if ( contype == NIL ) {
561 			    contype = p1;
562 			    if ( contype == lookup( intset ) -> type ) {
563 				codeoff();
564 				contype = rvalue( r[2] , NIL , LREQ );
565 				codeon();
566 			    }
567 			}
568 			if ( contype == NIL ) {
569 			    return NIL;
570 			}
571 			    /*
572 			     *	allocate a temporary and use it
573 			     */
574 			tempnlp = tmpalloc(lwidth(contype), contype, NOREG);
575 			putLV( 0 , cbn , tempnlp -> value[ NL_OFFS ] ,
576 				tempnlp -> extra_flags , P2PTR|P2STRTY );
577 			p = rvalue( r[2] , contype , LREQ );
578 			if ( isa( p , "t" ) ) {
579 			    putop( P2LISTOP , P2INT );
580 			    if ( p == NIL || p1 == NIL ) {
581 				return NIL;
582 			    }
583 			    p1 = rvalue( r[3] , p , LREQ );
584 			    if ( p != p1 ) {
585 				error("Set types of operands of %s must be identical", opname);
586 				return NIL;
587 			    }
588 			    putop( P2LISTOP , P2INT );
589 			    putleaf( P2ICON , lwidth( p1 ) / sizeof( long ) , 0
590 				    , P2INT , 0 );
591 			    putop( P2LISTOP , P2INT );
592 			    putop( P2CALL , P2PTR | P2STRTY );
593 			    return p;
594 			}
595 		    }
596 		    if ( isnta( p1 , "idt" ) ) {
597 			    /*
598 			     *	find type of left operand for error message.
599 			     */
600 			p = rvalue( r[2] , contype , RREQ );
601 		    }
602 			/*
603 			 *	don't give spurious error messages.
604 			 */
605 		    if ( p == NIL || p1 == NIL ) {
606 			return NIL;
607 		    }
608 #		endif PC
609 		if (isnta(p, "idt")) {
610 			error("Left operand of %s must be integer, real or set, not %s", opname, nameof(p));
611 			return (NIL);
612 		}
613 		if (isnta(p1, "idt")) {
614 			error("Right operand of %s must be integer, real or set, not %s", opname, nameof(p1));
615 			return (NIL);
616 		}
617 		error("Cannot mix sets with integers and reals as operands of %s", opname);
618 		return (NIL);
619 
620 	case T_MOD:
621 	case T_DIV:
622 		p = rvalue(r[2], NIL , RREQ );
623 #		ifdef PC
624 		    sconv(p2type(p), P2INT);
625 #		endif PC
626 		p1 = rvalue(r[3], NIL , RREQ );
627 #		ifdef PC
628 		    sconv(p2type(p1), P2INT);
629 #		endif PC
630 		if (p == NIL || p1 == NIL)
631 			return (NIL);
632 		if (isnta(p, "i")) {
633 			error("Left operand of %s must be integer, not %s", opname, nameof(p));
634 			return (NIL);
635 		}
636 		if (isnta(p1, "i")) {
637 			error("Right operand of %s must be integer, not %s", opname, nameof(p1));
638 			return (NIL);
639 		}
640 #		ifdef OBJ
641 		    return (gen(NIL, r[0], width(p), width(p1)));
642 #		endif OBJ
643 #		ifdef PC
644 		    putop( r[ 0 ] == T_DIV ? P2DIV : P2MOD , P2INT );
645 		    return ( nl + T4INT );
646 #		endif PC
647 
648 	case T_EQ:
649 	case T_NE:
650 	case T_LT:
651 	case T_GT:
652 	case T_LE:
653 	case T_GE:
654 		/*
655 		 * Since there can be no, a priori, knowledge
656 		 * of the context type should a constant string
657 		 * or set arise, we must poke around to find such
658 		 * a type if possible.  Since constant strings can
659 		 * always masquerade as identifiers, this is always
660 		 * necessary.
661 		 */
662 		codeoff();
663 		p1 = rvalue(r[3], NIL , RREQ );
664 		codeon();
665 		if (p1 == NIL)
666 			return (NIL);
667 		contype = p1;
668 #		ifdef OBJ
669 		    if (p1->class == STR) {
670 			    /*
671 			     * For constant strings we want
672 			     * the longest type so as to be
673 			     * able to do padding (more importantly
674 			     * avoiding truncation). For clarity,
675 			     * we get this length here.
676 			     */
677 			    codeoff();
678 			    p = rvalue(r[2], NIL , RREQ );
679 			    codeon();
680 			    if (p == NIL)
681 				    return (NIL);
682 			    if (width(p) > width(p1))
683 				    contype = p;
684 		    } else if ( isa( p1 , "t" ) ) {
685 			if ( contype == lookup( intset ) -> type ) {
686 			    codeoff();
687 			    contype = rvalue( r[2] , NIL , RREQ );
688 			    codeon();
689 			    if ( contype == NIL ) {
690 				return NIL;
691 			    }
692 			}
693 		    }
694 		    /*
695 		     * Now we generate code for
696 		     * the operands of the relational
697 		     * operation.
698 		     */
699 		    p = rvalue(r[2], contype , RREQ );
700 		    if (p == NIL)
701 			    return (NIL);
702 		    p1 = rvalue(r[3], p , RREQ );
703 		    if (p1 == NIL)
704 			    return (NIL);
705 #		endif OBJ
706 #		ifdef PC
707 		    c1 = classify( p1 );
708 		    if ( c1 == TSET || c1 == TSTR || c1 == TREC ) {
709 			putleaf( P2ICON , 0 , 0
710 				, ADDTYPE( P2FTN | P2INT , P2PTR )
711 				, c1 == TSET  ? relts[ r[0] - T_EQ ]
712 					      : relss[ r[0] - T_EQ ] );
713 			    /*
714 			     *	for [] and strings, comparisons are done on
715 			     *	the maximum width of the two sides.
716 			     *	for other sets, we have to ask the left side
717 			     *	what type it is based on the type of the right.
718 			     *	(this matters for intsets).
719 			     */
720 			if ( c1 == TSTR ) {
721 			    codeoff();
722 			    p = rvalue( r[ 2 ] , NIL , LREQ );
723 			    codeon();
724 			    if ( p == NIL ) {
725 				return NIL;
726 			    }
727 			    if ( lwidth( p ) > lwidth( p1 ) ) {
728 				contype = p;
729 			    }
730 			} else if ( c1 == TSET ) {
731 			    if ( contype == lookup( intset ) -> type ) {
732 				codeoff();
733 				p = rvalue( r[ 2 ] , NIL , LREQ );
734 				codeon();
735 				if ( p == NIL ) {
736 				    return NIL;
737 				}
738 				contype = p;
739 			    }
740 			}
741 			    /*
742 			     *	put out the width of the comparison.
743 			     */
744 			putleaf( P2ICON , lwidth( contype ) , 0 , P2INT , 0 );
745 			    /*
746 			     *	and the left hand side,
747 			     *	for sets, strings, records
748 			     */
749 			p = rvalue( r[ 2 ] , contype , LREQ );
750 			if ( p == NIL ) {
751 			    return NIL;
752 			}
753 			putop( P2LISTOP , P2INT );
754 			p1 = rvalue( r[ 3 ] , p , LREQ );
755 			if ( p1 == NIL ) {
756 			    return NIL;
757 			}
758 			putop( P2LISTOP , P2INT );
759 			putop( P2CALL , P2INT );
760 		    } else {
761 			    /*
762 			     *	the easy (scalar or error) case
763 			     */
764 			p = rvalue( r[ 2 ] , contype , RREQ );
765 			if ( p == NIL ) {
766 			    return NIL;
767 			}
768 			    /*
769 			     * since the second pass can't do
770 			     *	long op double  or  double op long
771 			     * we may have to do some coercing.
772 			     */
773 			tuac(p, p1, &rettype, &ctype);
774 			p1 = rvalue( r[ 3 ] , p , RREQ );
775 			if ( p1 == NIL ) {
776 			    return NIL;
777 			}
778 			tuac(p1, p, &rettype, &ctype);
779 			putop( relops[ r[0] - T_EQ ] , P2INT );
780 			sconv(P2INT, P2CHAR);
781 		    }
782 #		endif PC
783 		c = classify(p);
784 		c1 = classify(p1);
785 		if (nocomp(c) || nocomp(c1))
786 			return (NIL);
787 		g = NIL;
788 		switch (c) {
789 			case TBOOL:
790 			case TCHAR:
791 				if (c != c1)
792 					goto clash;
793 				break;
794 			case TINT:
795 			case TDOUBLE:
796 				if (c1 != TINT && c1 != TDOUBLE)
797 					goto clash;
798 				break;
799 			case TSCAL:
800 				if (c1 != TSCAL)
801 					goto clash;
802 				if (scalar(p) != scalar(p1))
803 					goto nonident;
804 				break;
805 			case TSET:
806 				if (c1 != TSET)
807 					goto clash;
808 				if ( opt( 's' ) &&
809 				    ( ( r[0] == T_LT ) || ( r[0] == T_GT ) ) &&
810 				    ( line != nssetline ) ) {
811 				    nssetline = line;
812 				    standard();
813 				    error("%s comparison on sets is non-standard" , opname );
814 				}
815 				if (p != p1)
816 					goto nonident;
817 				g = TSET;
818 				break;
819 			case TREC:
820 				if ( c1 != TREC ) {
821 				    goto clash;
822 				}
823 				if ( p != p1 ) {
824 				    goto nonident;
825 				}
826 				if (r[0] != T_EQ && r[0] != T_NE) {
827 					error("%s not allowed on records - only allow = and <>" , opname );
828 					return (NIL);
829 				}
830 				g = TREC;
831 				break;
832 			case TPTR:
833 			case TNIL:
834 				if (c1 != TPTR && c1 != TNIL)
835 					goto clash;
836 				if (r[0] != T_EQ && r[0] != T_NE) {
837 					error("%s not allowed on pointers - only allow = and <>" , opname );
838 					return (NIL);
839 				}
840 				break;
841 			case TSTR:
842 				if (c1 != TSTR)
843 					goto clash;
844 				if (width(p) != width(p1)) {
845 					error("Strings not same length in %s comparison", opname);
846 					return (NIL);
847 				}
848 				g = TSTR;
849 				break;
850 			default:
851 				panic("rval2");
852 		}
853 #		ifdef OBJ
854 		    return (gen(g, r[0], width(p), width(p1)));
855 #		endif OBJ
856 #		ifdef PC
857 		    return nl + TBOOL;
858 #		endif PC
859 clash:
860 		error("%ss and %ss cannot be compared - operator was %s", clnames[c], clnames[c1], opname);
861 		return (NIL);
862 nonident:
863 		error("%s types must be identical in comparisons - operator was %s", clnames[c1], opname);
864 		return (NIL);
865 
866 	case T_IN:
867 	    rt = r[3];
868 #	    ifdef OBJ
869 		if (rt != NIL && rt[0] == T_CSET) {
870 			precset( rt , NIL , &csetd );
871 			p1 = csetd.csettype;
872 			if (p1 == NIL)
873 			    return NIL;
874 			postcset( rt, &csetd);
875 		    } else {
876 			p1 = stkrval(r[3], NIL , RREQ );
877 			rt = NIL;
878 		    }
879 #		endif OBJ
880 #		ifdef PC
881 		    if (rt != NIL && rt[0] == T_CSET) {
882 			if ( precset( rt , NIL , &csetd ) ) {
883 			    putleaf( P2ICON , 0 , 0
884 				    , ADDTYPE( P2FTN | P2INT , P2PTR )
885 				    , "_IN" );
886 			} else {
887 			    putleaf( P2ICON , 0 , 0
888 				    , ADDTYPE( P2FTN | P2INT , P2PTR )
889 				    , "_INCT" );
890 			}
891 			p1 = csetd.csettype;
892 			if (p1 == NIL)
893 			    return NIL;
894 		    } else {
895 			putleaf( P2ICON , 0 , 0
896 				, ADDTYPE( P2FTN | P2INT , P2PTR )
897 				, "_IN" );
898 			codeoff();
899 			p1 = rvalue(r[3], NIL , LREQ );
900 			codeon();
901 		    }
902 #		endif PC
903 		p = stkrval(r[2], NIL , RREQ );
904 		if (p == NIL || p1 == NIL)
905 			return (NIL);
906 		if (p1->class != SET) {
907 			error("Right operand of 'in' must be a set, not %s", nameof(p1));
908 			return (NIL);
909 		}
910 		if (incompat(p, p1->type, r[2])) {
911 			cerror("Index type clashed with set component type for 'in'");
912 			return (NIL);
913 		}
914 		setran(p1->type);
915 #		ifdef OBJ
916 		    if (rt == NIL || csetd.comptime)
917 			    put(4, O_IN, width(p1), set.lwrb, set.uprbp);
918 		    else
919 			    put(2, O_INCT,
920 				(int)(3 + csetd.singcnt + 2*csetd.paircnt));
921 #		endif OBJ
922 #		ifdef PC
923 		    if ( rt == NIL || rt[0] != T_CSET ) {
924 			putleaf( P2ICON , set.lwrb , 0 , P2INT , 0 );
925 			putop( P2LISTOP , P2INT );
926 			putleaf( P2ICON , set.uprbp , 0 , P2INT , 0 );
927 			putop( P2LISTOP , P2INT );
928 			p1 = rvalue( r[3] , NIL , LREQ );
929 			if ( p1 == NIL ) {
930 			    return NIL;
931 			}
932 			putop( P2LISTOP , P2INT );
933 		    } else if ( csetd.comptime ) {
934 			putleaf( P2ICON , set.lwrb , 0 , P2INT , 0 );
935 			putop( P2LISTOP , P2INT );
936 			putleaf( P2ICON , set.uprbp , 0 , P2INT , 0 );
937 			putop( P2LISTOP , P2INT );
938 			postcset( r[3] , &csetd );
939 			putop( P2LISTOP , P2INT );
940 		    } else {
941 			postcset( r[3] , &csetd );
942 		    }
943 		    putop( P2CALL , P2INT );
944 		    sconv(P2INT, P2CHAR);
945 #		endif PC
946 		return (nl+T1BOOL);
947 	default:
948 		if (r[2] == NIL)
949 			return (NIL);
950 		switch (r[0]) {
951 		default:
952 			panic("rval3");
953 
954 
955 		/*
956 		 * An octal number
957 		 */
958 		case T_BINT:
959 			f = a8tol(r[2]);
960 			goto conint;
961 
962 		/*
963 		 * A decimal number
964 		 */
965 		case T_INT:
966 			f = atof(r[2]);
967 conint:
968 			if (f > MAXINT || f < MININT) {
969 				error("Constant too large for this implementation");
970 				return (NIL);
971 			}
972 			l = f;
973 #			ifdef OBJ
974 			    if (bytes(l, l) <= 2) {
975 				    put(2, O_CON2, ( short ) l);
976 				    return (nl+T2INT);
977 			    }
978 			    put(2, O_CON4, l);
979 			    return (nl+T4INT);
980 #			endif OBJ
981 #			ifdef PC
982 			    switch (bytes(l, l)) {
983 				case 1:
984 				    putleaf(P2ICON, l, 0, P2CHAR, 0);
985 				    return nl+T1INT;
986 				case 2:
987 				    putleaf(P2ICON, l, 0, P2SHORT, 0);
988 				    return nl+T2INT;
989 				case 4:
990 				    putleaf(P2ICON, l, 0, P2INT, 0);
991 				    return nl+T4INT;
992 			    }
993 #			endif PC
994 
995 		/*
996 		 * A floating point number
997 		 */
998 		case T_FINT:
999 #			ifdef OBJ
1000 			    put(2, O_CON8, atof(r[2]));
1001 #			endif OBJ
1002 #			ifdef PC
1003 			    putCON8( atof( r[2] ) );
1004 #			endif PC
1005 			return (nl+TDOUBLE);
1006 
1007 		/*
1008 		 * Constant strings.  Note that constant characters
1009 		 * are constant strings of length one; there is
1010 		 * no constant string of length one.
1011 		 */
1012 		case T_STRNG:
1013 			cp = r[2];
1014 			if (cp[1] == 0) {
1015 #				ifdef OBJ
1016 				    put(2, O_CONC, cp[0]);
1017 #				endif OBJ
1018 #				ifdef PC
1019 				    putleaf( P2ICON , cp[0] , 0 , P2CHAR , 0 );
1020 #				endif PC
1021 				return (nl+T1CHAR);
1022 			}
1023 			goto cstrng;
1024 		}
1025 
1026 	}
1027 }
1028 
1029 /*
1030  * Can a class appear
1031  * in a comparison ?
1032  */
1033 nocomp(c)
1034 	int c;
1035 {
1036 
1037 	switch (c) {
1038 		case TREC:
1039 			if ( line != reccompline ) {
1040 			    reccompline = line;
1041 			    warning();
1042 			    if ( opt( 's' ) ) {
1043 				standard();
1044 			    }
1045 			    error("record comparison is non-standard");
1046 			}
1047 			break;
1048 		case TFILE:
1049 		case TARY:
1050 			error("%ss may not participate in comparisons", clnames[c]);
1051 			return (1);
1052 	}
1053 	return (NIL);
1054 }
1055 
1056     /*
1057      *	this is sort of like gconst, except it works on expression trees
1058      *	rather than declaration trees, and doesn't give error messages for
1059      *	non-constant things.
1060      *	as a side effect this fills in the con structure that gconst uses.
1061      *	this returns TRUE or FALSE.
1062      */
1063 constval(r)
1064 	register int *r;
1065 {
1066 	register struct nl *np;
1067 	register *cn;
1068 	char *cp;
1069 	int negd, sgnd;
1070 	long ci;
1071 
1072 	con.ctype = NIL;
1073 	cn = r;
1074 	negd = sgnd = 0;
1075 loop:
1076 	    /*
1077 	     *	cn[2] is nil if error recovery generated a T_STRNG
1078 	     */
1079 	if (cn == NIL || cn[2] == NIL)
1080 		return FALSE;
1081 	switch (cn[0]) {
1082 		default:
1083 			return FALSE;
1084 		case T_MINUS:
1085 			negd = 1 - negd;
1086 			/* and fall through */
1087 		case T_PLUS:
1088 			sgnd++;
1089 			cn = cn[2];
1090 			goto loop;
1091 		case T_NIL:
1092 			con.cpval = NIL;
1093 			con.cival = 0;
1094 			con.crval = con.cival;
1095 			con.ctype = nl + TNIL;
1096 			break;
1097 		case T_VAR:
1098 			np = lookup(cn[2]);
1099 			if (np == NIL || np->class != CONST) {
1100 				return FALSE;
1101 			}
1102 			if ( cn[3] != NIL ) {
1103 				return FALSE;
1104 			}
1105 			con.ctype = np->type;
1106 			switch (classify(np->type)) {
1107 				case TINT:
1108 					con.crval = np->range[0];
1109 					break;
1110 				case TDOUBLE:
1111 					con.crval = np->real;
1112 					break;
1113 				case TBOOL:
1114 				case TCHAR:
1115 				case TSCAL:
1116 					con.cival = np->value[0];
1117 					con.crval = con.cival;
1118 					break;
1119 				case TSTR:
1120 					con.cpval = np->ptr[0];
1121 					break;
1122 				default:
1123 					con.ctype = NIL;
1124 					return FALSE;
1125 			}
1126 			break;
1127 		case T_BINT:
1128 			con.crval = a8tol(cn[2]);
1129 			goto restcon;
1130 		case T_INT:
1131 			con.crval = atof(cn[2]);
1132 			if (con.crval > MAXINT || con.crval < MININT) {
1133 				derror("Constant too large for this implementation");
1134 				con.crval = 0;
1135 			}
1136 restcon:
1137 			ci = con.crval;
1138 #ifndef PI0
1139 			if (bytes(ci, ci) <= 2)
1140 				con.ctype = nl+T2INT;
1141 			else
1142 #endif
1143 				con.ctype = nl+T4INT;
1144 			break;
1145 		case T_FINT:
1146 			con.ctype = nl+TDOUBLE;
1147 			con.crval = atof(cn[2]);
1148 			break;
1149 		case T_STRNG:
1150 			cp = cn[2];
1151 			if (cp[1] == 0) {
1152 				con.ctype = nl+T1CHAR;
1153 				con.cival = cp[0];
1154 				con.crval = con.cival;
1155 				break;
1156 			}
1157 			con.ctype = nl+TSTR;
1158 			con.cpval = cp;
1159 			break;
1160 	}
1161 	if (sgnd) {
1162 		if (isnta(con.ctype, "id")) {
1163 			derror("%s constants cannot be signed", nameof(con.ctype));
1164 			return FALSE;
1165 		} else if (negd)
1166 			con.crval = -con.crval;
1167 	}
1168 	return TRUE;
1169 }
1170