xref: /csrg-svn/usr.bin/pascal/src/rval.c (revision 3227)
1 /* Copyright (c) 1979 Regents of the University of California */
2 
3 static char sccsid[] = "@(#)rval.c 1.10 03/11/81";
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 
20 #ifdef PC
21     char	*relts[] =  {
22 				"_RELEQ" , "_RELNE" ,
23 				"_RELTLT" , "_RELTGT" ,
24 				"_RELTLE" , "_RELTGE"
25 			    };
26     char	*relss[] =  {
27 				"_RELEQ" , "_RELNE" ,
28 				"_RELSLT" , "_RELSGT" ,
29 				"_RELSLE" , "_RELSGE"
30 			    };
31     long	relops[] =  {
32 				P2EQ , P2NE ,
33 				P2LT , P2GT ,
34 				P2LE , P2GE
35 			    };
36     long	mathop[] =  {	P2MUL , P2PLUS , P2MINUS };
37     char	*setop[] =  {	"_MULT" , "_ADDT" , "_SUBT" };
38 #endif PC
39 /*
40  * Rvalue - an expression.
41  *
42  * Contype is the type that the caller would prefer, nand is important
43  * if constant sets or constant strings are involved, the latter
44  * because of string padding.
45  * required is a flag whether an lvalue or an rvalue is required.
46  * only VARs and structured things can have gt their lvalue this way.
47  */
48 struct nl *
49 rvalue(r, contype , required )
50 	int *r;
51 	struct nl *contype;
52 	int	required;
53 {
54 	register struct nl *p, *p1;
55 	register struct nl *q;
56 	int c, c1, *rt, w, g;
57 	char *cp, *cp1, *opname;
58 	long l;
59 	double f;
60 	extern int	flagwas;
61 	struct csetstr	csetd;
62 #	ifdef PC
63 	    struct nl	*rettype;
64 	    long	ctype;
65 	    long	tempoff;
66 #	endif PC
67 
68 	if (r == NIL)
69 		return (NIL);
70 	if (nowexp(r))
71 		return (NIL);
72 	/*
73 	 * Pick up the name of the operation
74 	 * for future error messages.
75 	 */
76 	if (r[0] <= T_IN)
77 		opname = opnames[r[0]];
78 
79 	/*
80 	 * The root of the tree tells us what sort of expression we have.
81 	 */
82 	switch (r[0]) {
83 
84 	/*
85 	 * The constant nil
86 	 */
87 	case T_NIL:
88 #		ifdef OBJ
89 		    put(2, O_CON2, 0);
90 #		endif OBJ
91 #		ifdef PC
92 		    putleaf( P2ICON , 0 , 0 , P2PTR|P2UNDEF , 0 );
93 #		endif PC
94 		return (nl+TNIL);
95 
96 	/*
97 	 * Function call with arguments.
98 	 */
99 	case T_FCALL:
100 #	    ifdef OBJ
101 		return (funccod(r));
102 #	    endif OBJ
103 #	    ifdef PC
104 		return (pcfunccod( r ));
105 #	    endif PC
106 
107 	case T_VAR:
108 		p = lookup(r[2]);
109 		if (p == NIL || p->class == BADUSE)
110 			return (NIL);
111 		switch (p->class) {
112 		    case VAR:
113 			    /*
114 			     * If a variable is
115 			     * qualified then get
116 			     * the rvalue by a
117 			     * lvalue and an ind.
118 			     */
119 			    if (r[3] != NIL)
120 				    goto ind;
121 			    q = p->type;
122 			    if (q == NIL)
123 				    return (NIL);
124 #			    ifdef OBJ
125 				w = width(q);
126 				switch (w) {
127 				    case 8:
128 					put(2, O_RV8 | bn << 8+INDX,
129 						(int)p->value[0]);
130 					break;
131 				    case 4:
132 					put(2, O_RV4 | bn << 8+INDX,
133 						(int)p->value[0]);
134 					break;
135 				    case 2:
136 					put(2, O_RV2 | bn << 8+INDX,
137 						(int)p->value[0]);
138 					break;
139 				    case 1:
140 					put(2, O_RV1 | bn << 8+INDX,
141 						(int)p->value[0]);
142 					break;
143 				    default:
144 					put(3, O_RV | bn << 8+INDX,
145 						(int)p->value[0], w);
146 				}
147 #			   endif OBJ
148 #			   ifdef PC
149 				if ( required == RREQ ) {
150 				    putRV( p -> symbol , bn , p -> value[0]
151 					    , p2type( q ) );
152 				} else {
153 				    putLV( p -> symbol , bn , p -> value[0]
154 					    , p2type( q ) );
155 				}
156 #			   endif PC
157 			   return (q);
158 
159 		    case WITHPTR:
160 		    case REF:
161 			    /*
162 			     * A lvalue for these
163 			     * is actually what one
164 			     * might consider a rvalue.
165 			     */
166 ind:
167 			    q = lvalue(r, NOFLAGS , LREQ );
168 			    if (q == NIL)
169 				    return (NIL);
170 #			    ifdef OBJ
171 				w = width(q);
172 				switch (w) {
173 				    case 8:
174 					    put(1, O_IND8);
175 					    break;
176 				    case 4:
177 					    put(1, O_IND4);
178 					    break;
179 				    case 2:
180 					    put(1, O_IND2);
181 					    break;
182 				    case 1:
183 					    put(1, O_IND1);
184 					    break;
185 				    default:
186 					    put(2, O_IND, w);
187 				}
188 #			    endif OBJ
189 #			    ifdef PC
190 				if ( required == RREQ ) {
191 				    putop( P2UNARY P2MUL , p2type( q ) );
192 				}
193 #			    endif PC
194 			    return (q);
195 
196 		    case CONST:
197 			    if (r[3] != NIL) {
198 				error("%s is a constant and cannot be qualified", r[2]);
199 				return (NIL);
200 			    }
201 			    q = p->type;
202 			    if (q == NIL)
203 				    return (NIL);
204 			    if (q == nl+TSTR) {
205 				    /*
206 				     * Find the size of the string
207 				     * constant if needed.
208 				     */
209 				    cp = p->ptr[0];
210 cstrng:
211 				    cp1 = cp;
212 				    for (c = 0; *cp++; c++)
213 					    continue;
214 				    w = c;
215 				    if (contype != NIL && !opt('s')) {
216 					    if (width(contype) < c && classify(contype) == TSTR) {
217 						    error("Constant string too long");
218 						    return (NIL);
219 					    }
220 					    w = width(contype);
221 				    }
222 #				    ifdef OBJ
223 					put(2, O_CONG, w);
224 					putstr(cp1, w - c);
225 #				    endif OBJ
226 #				    ifdef PC
227 					putCONG( cp1 , w , required );
228 #				    endif PC
229 				    /*
230 				     * Define the string temporarily
231 				     * so later people can know its
232 				     * width.
233 				     * cleaned out by stat.
234 				     */
235 				    q = defnl(0, STR, 0, w);
236 				    q->type = q;
237 				    return (q);
238 			    }
239 			    if (q == nl+T1CHAR) {
240 #				    ifdef OBJ
241 					put(2, O_CONC, (int)p->value[0]);
242 #				    endif OBJ
243 #				    ifdef PC
244 					putleaf( P2ICON , p -> value[0] , 0
245 						, P2CHAR , 0 );
246 #				    endif PC
247 				    return (q);
248 			    }
249 			    /*
250 			     * Every other kind of constant here
251 			     */
252 			    switch (width(q)) {
253 			    case 8:
254 #ifndef DEBUG
255 #				    ifdef OBJ
256 					put(2, O_CON8, p->real);
257 #				    endif OBJ
258 #				    ifdef PC
259 					putCON8( p -> real );
260 #				    endif PC
261 #else
262 				    if (hp21mx) {
263 					    f = p->real;
264 					    conv(&f);
265 					    l = f.plong;
266 					    put(2, O_CON4, l);
267 				    } else
268 #					    ifdef OBJ
269 						put(2, O_CON8, p->real);
270 #					    endif OBJ
271 #					    ifdef PC
272 						putCON8( p -> real );
273 #					    endif PC
274 #endif
275 				    break;
276 			    case 4:
277 #				    ifdef OBJ
278 					put(2, O_CON4, p->range[0]);
279 #				    endif OBJ
280 #				    ifdef PC
281 					putleaf( P2ICON , p -> range[0] , 0
282 						, P2INT , 0 );
283 #				    endif PC
284 				    break;
285 			    case 2:
286 #				    ifdef OBJ
287 					put(2, O_CON2, (short)p->range[0]);
288 #				    endif OBJ
289 #				    ifdef PC
290 					    /*
291 					     * make short constants ints
292 					     */
293 					putleaf( P2ICON , (short) p -> range[0]
294 						, 0 , P2INT , 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 					    /*
303 					     * make char constants ints
304 					     */
305 					putleaf( P2ICON , p -> value[0] , 0
306 						, P2INT , 0 );
307 #				    endif PC
308 				    break;
309 			    default:
310 				    panic("rval");
311 			    }
312 			    return (q);
313 
314 		    case FUNC:
315 		    case FFUNC:
316 			    /*
317 			     * Function call with no arguments.
318 			     */
319 			    if (r[3]) {
320 				    error("Can't qualify a function result value");
321 				    return (NIL);
322 			    }
323 #			    ifdef OBJ
324 				return (funccod((int *) r));
325 #			    endif OBJ
326 #			    ifdef PC
327 				return (pcfunccod( r ));
328 #			    endif PC
329 
330 		    case TYPE:
331 			    error("Type names (e.g. %s) allowed only in declarations", p->symbol);
332 			    return (NIL);
333 
334 		    case PROC:
335 		    case FPROC:
336 			    error("Procedure %s found where expression required", p->symbol);
337 			    return (NIL);
338 		    default:
339 			    panic("rvid");
340 		}
341 	/*
342 	 * Constant sets
343 	 */
344 	case T_CSET:
345 #		ifdef OBJ
346 		    if ( precset( r , contype , &csetd ) ) {
347 			if ( csetd.csettype == NIL ) {
348 			    return NIL;
349 			}
350 			postcset( r , &csetd );
351 		    } else {
352 			put( 2, O_PUSH, -lwidth(csetd.csettype));
353 			postcset( r , &csetd );
354 			setran( ( csetd.csettype ) -> type );
355 			put( 2, O_CON24, set.uprbp);
356 			put( 2, O_CON24, set.lwrb);
357 			put( 2, O_CTTOT,
358 				(int)(4 + csetd.singcnt + 2 * csetd.paircnt));
359 		    }
360 		    return csetd.csettype;
361 #		endif OBJ
362 #		ifdef PC
363 		    if ( precset( r , contype , &csetd ) ) {
364 			if ( csetd.csettype == NIL ) {
365 			    return NIL;
366 			}
367 			postcset( r , &csetd );
368 		    } else {
369 			putleaf( P2ICON , 0 , 0
370 				, ADDTYPE( P2FTN | P2INT , P2PTR )
371 				, "_CTTOT" );
372 			/*
373 			 *	allocate a temporary and use it
374 			 */
375 			tempoff = tmpalloc(lwidth(csetd.csettype),
376 				csetd.csettype, NOREG);
377 			putLV( 0 , cbn , tempoff , P2PTR|P2STRTY );
378 			setran( ( csetd.csettype ) -> type );
379 			putleaf( P2ICON , set.lwrb , 0 , P2INT , 0 );
380 			putop( P2LISTOP , P2INT );
381 			putleaf( P2ICON , set.uprbp , 0 , P2INT , 0 );
382 			putop( P2LISTOP , P2INT );
383 			postcset( r , &csetd );
384 			putop( P2CALL , P2INT );
385 		    }
386 		    return csetd.csettype;
387 #		endif PC
388 
389 	/*
390 	 * Unary plus and minus
391 	 */
392 	case T_PLUS:
393 	case T_MINUS:
394 		q = rvalue(r[2], NIL , RREQ );
395 		if (q == NIL)
396 			return (NIL);
397 		if (isnta(q, "id")) {
398 			error("Operand of %s must be integer or real, not %s", opname, nameof(q));
399 			return (NIL);
400 		}
401 		if (r[0] == T_MINUS) {
402 #		    ifdef OBJ
403 			put(1, O_NEG2 + (width(q) >> 2));
404 #		    endif OBJ
405 #		    ifdef PC
406 			putop( P2UNARY P2MINUS , p2type( q ) );
407 #		    endif PC
408 		    return (isa(q, "d") ? q : nl+T4INT);
409 		}
410 		return (q);
411 
412 	case T_NOT:
413 		q = rvalue(r[2], NIL , RREQ );
414 		if (q == NIL)
415 			return (NIL);
416 		if (isnta(q, "b")) {
417 			error("not must operate on a Boolean, not %s", nameof(q));
418 			return (NIL);
419 		}
420 #		ifdef OBJ
421 		    put(1, O_NOT);
422 #		endif OBJ
423 #		ifdef PC
424 		    putop( P2NOT , P2INT );
425 #		endif PC
426 		return (nl+T1BOOL);
427 
428 	case T_AND:
429 	case T_OR:
430 		p = rvalue(r[2], NIL , RREQ );
431 		p1 = rvalue(r[3], NIL , RREQ );
432 		if (p == NIL || p1 == NIL)
433 			return (NIL);
434 		if (isnta(p, "b")) {
435 			error("Left operand of %s must be Boolean, not %s", opname, nameof(p));
436 			return (NIL);
437 		}
438 		if (isnta(p1, "b")) {
439 			error("Right operand of %s must be Boolean, not %s", opname, nameof(p1));
440 			return (NIL);
441 		}
442 #		ifdef OBJ
443 		    put(1, r[0] == T_AND ? O_AND : O_OR);
444 #		endif OBJ
445 #		ifdef PC
446 			/*
447 			 * note the use of & and | rather than && and ||
448 			 * to force evaluation of all the expressions.
449 			 */
450 		    putop( r[ 0 ] == T_AND ? P2AND : P2OR , P2INT );
451 #		endif PC
452 		return (nl+T1BOOL);
453 
454 	case T_DIVD:
455 #		ifdef OBJ
456 		    p = rvalue(r[2], NIL , RREQ );
457 		    p1 = rvalue(r[3], NIL , RREQ );
458 #		endif OBJ
459 #		ifdef PC
460 			/*
461 			 *	force these to be doubles for the divide
462 			 */
463 		    p = rvalue( r[ 2 ] , NIL , RREQ );
464 		    if ( isnta( p , "d" ) ) {
465 			putop( P2SCONV , P2DOUBLE );
466 		    }
467 		    p1 = rvalue( r[ 3 ] , NIL , RREQ );
468 		    if ( isnta( p1 , "d" ) ) {
469 			putop( P2SCONV , P2DOUBLE );
470 		    }
471 #		endif PC
472 		if (p == NIL || p1 == NIL)
473 			return (NIL);
474 		if (isnta(p, "id")) {
475 			error("Left operand of / must be integer or real, not %s", nameof(p));
476 			return (NIL);
477 		}
478 		if (isnta(p1, "id")) {
479 			error("Right operand of / must be integer or real, not %s", nameof(p1));
480 			return (NIL);
481 		}
482 #		ifdef OBJ
483 		    return gen(NIL, r[0], width(p), width(p1));
484 #		endif OBJ
485 #		ifdef PC
486 		    putop( P2DIV , P2DOUBLE );
487 		    return nl + TDOUBLE;
488 #		endif PC
489 
490 	case T_MULT:
491 	case T_ADD:
492 	case T_SUB:
493 #		ifdef OBJ
494 		    /*
495 		     * If the context hasn't told us the type
496 		     * and a constant set is present
497 		     * we need to infer the type
498 		     * before generating code.
499 		     */
500 		    if ( contype == NIL ) {
501 			    codeoff();
502 			    contype = rvalue( r[3] , NIL , RREQ );
503 			    codeon();
504 			    if ( contype == lookup( intset ) -> type ) {
505 				codeoff();
506 				contype = rvalue( r[2] , NIL , RREQ );
507 				codeon();
508 			    }
509 		    }
510 		    if ( contype == NIL ) {
511 			return NIL;
512 		    }
513 		    p = rvalue( r[2] , contype , RREQ );
514 		    p1 = rvalue( r[3] , p , RREQ );
515 		    if ( p == NIL || p1 == NIL )
516 			    return NIL;
517 		    if (isa(p, "id") && isa(p1, "id"))
518 			return (gen(NIL, r[0], width(p), width(p1)));
519 		    if (isa(p, "t") && isa(p1, "t")) {
520 			    if (p != p1) {
521 				    error("Set types of operands of %s must be identical", opname);
522 				    return (NIL);
523 			    }
524 			    gen(TSET, r[0], width(p), 0);
525 			    return (p);
526 		    }
527 #		endif OBJ
528 #		ifdef PC
529 			/*
530 			 * the second pass can't do
531 			 *	long op double  or  double op long
532 			 * so we have to know the type of both operands
533 			 * also, it gets tricky for sets, which are done
534 			 * by function calls.
535 			 */
536 		    codeoff();
537 		    p1 = rvalue( r[ 3 ] , contype , RREQ );
538 		    codeon();
539 		    if ( isa( p1 , "id" ) ) {
540 			p = rvalue( r[ 2 ] , contype , RREQ );
541 			if ( ( p == NIL ) || ( p1 == NIL ) ) {
542 			    return NIL;
543 			}
544 			if ( isa( p , "i" ) && isa( p1 , "d" ) ) {
545 			    putop( P2SCONV , P2DOUBLE );
546 			}
547 			p1 = rvalue( r[ 3 ] , contype , RREQ );
548 			if ( isa( p , "d" ) && isa( p1 , "i" ) ) {
549 			    putop( P2SCONV , P2DOUBLE );
550 			}
551 			if ( isa( p , "id" ) ) {
552 			    if ( isa( p , "d" ) || isa( p1 , "d" ) ) {
553 				ctype = P2DOUBLE;
554 				rettype = nl + TDOUBLE;
555 			    } else {
556 				ctype = P2INT;
557 				rettype = nl + T4INT;
558 			    }
559 			    putop( mathop[ r[0] - T_MULT ] , ctype );
560 			    return rettype;
561 			}
562 		    }
563 		    if ( isa( p1 , "t" ) ) {
564 			putleaf( P2ICON , 0 , 0
565 			    , ADDTYPE( ADDTYPE( P2PTR | P2STRTY , P2FTN )
566 					, P2PTR )
567 			    , setop[ r[0] - T_MULT ] );
568 			if ( contype == NIL ) {
569 			    contype = p1;
570 			    if ( contype == lookup( intset ) -> type ) {
571 				codeoff();
572 				contype = rvalue( r[2] , NIL , LREQ );
573 				codeon();
574 			    }
575 			}
576 			if ( contype == NIL ) {
577 			    return NIL;
578 			}
579 			    /*
580 			     *	allocate a temporary and use it
581 			     */
582 			tempoff = tmpalloc(lwidth(contype), contype, NOREG);
583 			putLV( 0 , cbn , tempoff , P2PTR|P2STRTY );
584 			p = rvalue( r[2] , contype , LREQ );
585 			if ( isa( p , "t" ) ) {
586 			    putop( P2LISTOP , P2INT );
587 			    if ( p == NIL || p1 == NIL ) {
588 				return NIL;
589 			    }
590 			    p1 = rvalue( r[3] , p , LREQ );
591 			    if ( p != p1 ) {
592 				error("Set types of operands of %s must be identical", opname);
593 				return NIL;
594 			    }
595 			    putop( P2LISTOP , P2INT );
596 			    putleaf( P2ICON , lwidth( p1 ) / sizeof( long ) , 0
597 				    , P2INT , 0 );
598 			    putop( P2LISTOP , P2INT );
599 			    putop( P2CALL , P2PTR | P2STRTY );
600 			    return p;
601 			}
602 		    }
603 		    if ( isnta( p1 , "idt" ) ) {
604 			    /*
605 			     *	find type of left operand for error message.
606 			     */
607 			p = rvalue( r[2] , contype , RREQ );
608 		    }
609 			/*
610 			 *	don't give spurious error messages.
611 			 */
612 		    if ( p == NIL || p1 == NIL ) {
613 			return NIL;
614 		    }
615 #		endif PC
616 		if (isnta(p, "idt")) {
617 			error("Left operand of %s must be integer, real or set, not %s", opname, nameof(p));
618 			return (NIL);
619 		}
620 		if (isnta(p1, "idt")) {
621 			error("Right operand of %s must be integer, real or set, not %s", opname, nameof(p1));
622 			return (NIL);
623 		}
624 		error("Cannot mix sets with integers and reals as operands of %s", opname);
625 		return (NIL);
626 
627 	case T_MOD:
628 	case T_DIV:
629 		p = rvalue(r[2], NIL , RREQ );
630 		p1 = rvalue(r[3], NIL , RREQ );
631 		if (p == NIL || p1 == NIL)
632 			return (NIL);
633 		if (isnta(p, "i")) {
634 			error("Left operand of %s must be integer, not %s", opname, nameof(p));
635 			return (NIL);
636 		}
637 		if (isnta(p1, "i")) {
638 			error("Right operand of %s must be integer, not %s", opname, nameof(p1));
639 			return (NIL);
640 		}
641 #		ifdef OBJ
642 		    return (gen(NIL, r[0], width(p), width(p1)));
643 #		endif OBJ
644 #		ifdef PC
645 		    putop( r[ 0 ] == T_DIV ? P2DIV : P2MOD , P2INT );
646 		    return ( nl + T4INT );
647 #		endif PC
648 
649 	case T_EQ:
650 	case T_NE:
651 	case T_LT:
652 	case T_GT:
653 	case T_LE:
654 	case T_GE:
655 		/*
656 		 * Since there can be no, a priori, knowledge
657 		 * of the context type should a constant string
658 		 * or set arise, we must poke around to find such
659 		 * a type if possible.  Since constant strings can
660 		 * always masquerade as identifiers, this is always
661 		 * necessary.
662 		 */
663 		codeoff();
664 		p1 = rvalue(r[3], NIL , RREQ );
665 		codeon();
666 		if (p1 == NIL)
667 			return (NIL);
668 		contype = p1;
669 #		ifdef OBJ
670 		    if (p1->class == STR) {
671 			    /*
672 			     * For constant strings we want
673 			     * the longest type so as to be
674 			     * able to do padding (more importantly
675 			     * avoiding truncation). For clarity,
676 			     * we get this length here.
677 			     */
678 			    codeoff();
679 			    p = rvalue(r[2], NIL , RREQ );
680 			    codeon();
681 			    if (p == NIL)
682 				    return (NIL);
683 			    if (width(p) > width(p1))
684 				    contype = p;
685 		    } else if ( isa( p1 , "t" ) ) {
686 			if ( contype == lookup( intset ) -> type ) {
687 			    codeoff();
688 			    contype = rvalue( r[2] , NIL , RREQ );
689 			    codeon();
690 			    if ( contype == NIL ) {
691 				return NIL;
692 			    }
693 			}
694 		    }
695 		    /*
696 		     * Now we generate code for
697 		     * the operands of the relational
698 		     * operation.
699 		     */
700 		    p = rvalue(r[2], contype , RREQ );
701 		    if (p == NIL)
702 			    return (NIL);
703 		    p1 = rvalue(r[3], p , RREQ );
704 		    if (p1 == NIL)
705 			    return (NIL);
706 #		endif OBJ
707 #		ifdef PC
708 		    c1 = classify( p1 );
709 		    if ( c1 == TSET || c1 == TSTR || c1 == TREC ) {
710 			putleaf( P2ICON , 0 , 0
711 				, ADDTYPE( P2FTN | P2INT , P2PTR )
712 				, c1 == TSET  ? relts[ r[0] - T_EQ ]
713 					      : relss[ r[0] - T_EQ ] );
714 			    /*
715 			     *	for [] and strings, comparisons are done on
716 			     *	the maximum width of the two sides.
717 			     *	for other sets, we have to ask the left side
718 			     *	what type it is based on the type of the right.
719 			     *	(this matters for intsets).
720 			     */
721 			if ( c1 == TSTR ) {
722 			    codeoff();
723 			    p = rvalue( r[ 2 ] , NIL , LREQ );
724 			    codeon();
725 			    if ( p == NIL ) {
726 				return NIL;
727 			    }
728 			    if ( lwidth( p ) > lwidth( p1 ) ) {
729 				contype = p;
730 			    }
731 			} else if ( c1 == TSET ) {
732 			    if ( contype == lookup( intset ) -> type ) {
733 				codeoff();
734 				p = rvalue( r[ 2 ] , NIL , LREQ );
735 				codeon();
736 				if ( p == NIL ) {
737 				    return NIL;
738 				}
739 				contype = p;
740 			    }
741 			}
742 			    /*
743 			     *	put out the width of the comparison.
744 			     */
745 			putleaf( P2ICON , lwidth( contype ) , 0 , P2INT , 0 );
746 			    /*
747 			     *	and the left hand side,
748 			     *	for sets, strings, records
749 			     */
750 			p = rvalue( r[ 2 ] , contype , LREQ );
751 			putop( P2LISTOP , P2INT );
752 			p1 = rvalue( r[ 3 ] , p , LREQ );
753 			putop( P2LISTOP , P2INT );
754 			putop( P2CALL , P2INT );
755 		    } else {
756 			    /*
757 			     *	the easy (scalar or error) case
758 			     */
759 			p = rvalue( r[ 2 ] , contype , RREQ );
760 			if ( p == NIL ) {
761 			    return NIL;
762 			}
763 			    /*
764 			     * since the second pass can't do
765 			     *	long op double  or  double op long
766 			     * we may have to do some coercing.
767 			     */
768 			if ( isa( p , "i" ) && isa( p1 , "d" ) ) {
769 			    putop( P2SCONV , P2DOUBLE );
770 			}
771 			p1 = rvalue( r[ 3 ] , p , RREQ );
772 			if ( isa( p , "d" ) && isa( p1 , "i" ) )
773 			    putop( P2SCONV , P2DOUBLE );
774 			putop( relops[ r[0] - T_EQ ] , P2INT );
775 		    }
776 #		endif PC
777 		c = classify(p);
778 		c1 = classify(p1);
779 		if (nocomp(c) || nocomp(c1))
780 			return (NIL);
781 		g = NIL;
782 		switch (c) {
783 			case TBOOL:
784 			case TCHAR:
785 				if (c != c1)
786 					goto clash;
787 				break;
788 			case TINT:
789 			case TDOUBLE:
790 				if (c1 != TINT && c1 != TDOUBLE)
791 					goto clash;
792 				break;
793 			case TSCAL:
794 				if (c1 != TSCAL)
795 					goto clash;
796 				if (scalar(p) != scalar(p1))
797 					goto nonident;
798 				break;
799 			case TSET:
800 				if (c1 != TSET)
801 					goto clash;
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 				break;
828 			case TSTR:
829 				if (c1 != TSTR)
830 					goto clash;
831 				if (width(p) != width(p1)) {
832 					error("Strings not same length in %s comparison", opname);
833 					return (NIL);
834 				}
835 				g = TSTR;
836 				break;
837 			default:
838 				panic("rval2");
839 		}
840 #		ifdef OBJ
841 		    return (gen(g, r[0], width(p), width(p1)));
842 #		endif OBJ
843 #		ifdef PC
844 		    return nl + TBOOL;
845 #		endif PC
846 clash:
847 		error("%ss and %ss cannot be compared - operator was %s", clnames[c], clnames[c1], opname);
848 		return (NIL);
849 nonident:
850 		error("%s types must be identical in comparisons - operator was %s", clnames[c1], opname);
851 		return (NIL);
852 
853 	case T_IN:
854 	    rt = r[3];
855 #	    ifdef OBJ
856 		if (rt != NIL && rt[0] == T_CSET) {
857 			precset( rt , NIL , &csetd );
858 			p1 = csetd.csettype;
859 			if (p1 == NIL)
860 			    return NIL;
861 			postcset( rt, &csetd);
862 		    } else {
863 			p1 = stkrval(r[3], NIL , RREQ );
864 			rt = NIL;
865 		    }
866 #		endif OBJ
867 #		ifdef PC
868 		    if (rt != NIL && rt[0] == T_CSET) {
869 			if ( precset( rt , NIL , &csetd ) ) {
870 			    putleaf( P2ICON , 0 , 0
871 				    , ADDTYPE( P2FTN | P2INT , P2PTR )
872 				    , "_IN" );
873 			} else {
874 			    putleaf( P2ICON , 0 , 0
875 				    , ADDTYPE( P2FTN | P2INT , P2PTR )
876 				    , "_INCT" );
877 			}
878 			p1 = csetd.csettype;
879 			if (p1 == NIL)
880 			    return NIL;
881 		    } else {
882 			putleaf( P2ICON , 0 , 0
883 				, ADDTYPE( P2FTN | P2INT , P2PTR )
884 				, "_IN" );
885 			codeoff();
886 			p1 = rvalue(r[3], NIL , LREQ );
887 			codeon();
888 		    }
889 #		endif PC
890 		p = stkrval(r[2], NIL , RREQ );
891 		if (p == NIL || p1 == NIL)
892 			return (NIL);
893 		if (p1->class != SET) {
894 			error("Right operand of 'in' must be a set, not %s", nameof(p1));
895 			return (NIL);
896 		}
897 		if (incompat(p, p1->type, r[2])) {
898 			cerror("Index type clashed with set component type for 'in'");
899 			return (NIL);
900 		}
901 		setran(p1->type);
902 #		ifdef OBJ
903 		    if (rt == NIL || csetd.comptime)
904 			    put(4, O_IN, width(p1), set.lwrb, set.uprbp);
905 		    else
906 			    put(2, O_INCT,
907 				(int)(3 + csetd.singcnt + 2*csetd.paircnt));
908 #		endif OBJ
909 #		ifdef PC
910 		    if ( rt == NIL || rt[0] != T_CSET ) {
911 			putleaf( P2ICON , set.lwrb , 0 , P2INT , 0 );
912 			putop( P2LISTOP , P2INT );
913 			putleaf( P2ICON , set.uprbp , 0 , P2INT , 0 );
914 			putop( P2LISTOP , P2INT );
915 			p1 = rvalue( r[3] , NIL , LREQ );
916 			putop( P2LISTOP , P2INT );
917 		    } else if ( csetd.comptime ) {
918 			putleaf( P2ICON , set.lwrb , 0 , P2INT , 0 );
919 			putop( P2LISTOP , P2INT );
920 			putleaf( P2ICON , set.uprbp , 0 , P2INT , 0 );
921 			putop( P2LISTOP , P2INT );
922 			postcset( r[3] , &csetd );
923 			putop( P2LISTOP , P2INT );
924 		    } else {
925 			postcset( r[3] , &csetd );
926 		    }
927 		    putop( P2CALL , P2INT );
928 #		endif PC
929 		return (nl+T1BOOL);
930 	default:
931 		if (r[2] == NIL)
932 			return (NIL);
933 		switch (r[0]) {
934 		default:
935 			panic("rval3");
936 
937 
938 		/*
939 		 * An octal number
940 		 */
941 		case T_BINT:
942 			f = a8tol(r[2]);
943 			goto conint;
944 
945 		/*
946 		 * A decimal number
947 		 */
948 		case T_INT:
949 			f = atof(r[2]);
950 conint:
951 			if (f > MAXINT || f < MININT) {
952 				error("Constant too large for this implementation");
953 				return (NIL);
954 			}
955 			l = f;
956 			if (bytes(l, l) <= 2) {
957 #				ifdef OBJ
958 				    put(2, O_CON2, ( short ) l);
959 #				endif OBJ
960 #				ifdef PC
961 				        /*
962 					 * short constants are ints
963 					 */
964 				    putleaf( P2ICON , l , 0 , P2INT , 0 );
965 #				endif PC
966 				return (nl+T2INT);
967 			}
968 #			ifdef OBJ
969 			    put(2, O_CON4, l);
970 #			endif OBJ
971 #			ifdef PC
972 			    putleaf( P2ICON , l , 0 , P2INT , 0 );
973 #			endif PC
974 			return (nl+T4INT);
975 
976 		/*
977 		 * A floating point number
978 		 */
979 		case T_FINT:
980 #			ifdef OBJ
981 			    put(2, O_CON8, atof(r[2]));
982 #			endif OBJ
983 #			ifdef PC
984 			    putCON8( atof( r[2] ) );
985 #			endif PC
986 			return (nl+TDOUBLE);
987 
988 		/*
989 		 * Constant strings.  Note that constant characters
990 		 * are constant strings of length one; there is
991 		 * no constant string of length one.
992 		 */
993 		case T_STRNG:
994 			cp = r[2];
995 			if (cp[1] == 0) {
996 #				ifdef OBJ
997 				    put(2, O_CONC, cp[0]);
998 #				endif OBJ
999 #				ifdef PC
1000 				    putleaf( P2ICON , cp[0] , 0 , P2CHAR , 0 );
1001 #				endif PC
1002 				return (nl+T1CHAR);
1003 			}
1004 			goto cstrng;
1005 		}
1006 
1007 	}
1008 }
1009 
1010 /*
1011  * Can a class appear
1012  * in a comparison ?
1013  */
1014 nocomp(c)
1015 	int c;
1016 {
1017 
1018 	switch (c) {
1019 		case TREC:
1020 			if ( line != reccompline ) {
1021 			    reccompline = line;
1022 			    warning();
1023 			    if ( opt( 's' ) ) {
1024 				standard();
1025 			    }
1026 			    error("record comparison is non-standard");
1027 			}
1028 			break;
1029 		case TFILE:
1030 		case TARY:
1031 			error("%ss may not participate in comparisons", clnames[c]);
1032 			return (1);
1033 	}
1034 	return (NIL);
1035 }
1036 
1037     /*
1038      *	this is sort of like gconst, except it works on expression trees
1039      *	rather than declaration trees, and doesn't give error messages for
1040      *	non-constant things.
1041      *	as a side effect this fills in the con structure that gconst uses.
1042      *	this returns TRUE or FALSE.
1043      */
1044 constval(r)
1045 	register int *r;
1046 {
1047 	register struct nl *np;
1048 	register *cn;
1049 	char *cp;
1050 	int negd, sgnd;
1051 	long ci;
1052 
1053 	con.ctype = NIL;
1054 	cn = r;
1055 	negd = sgnd = 0;
1056 loop:
1057 	    /*
1058 	     *	cn[2] is nil if error recovery generated a T_STRNG
1059 	     */
1060 	if (cn == NIL || cn[2] == NIL)
1061 		return FALSE;
1062 	switch (cn[0]) {
1063 		default:
1064 			return FALSE;
1065 		case T_MINUS:
1066 			negd = 1 - negd;
1067 			/* and fall through */
1068 		case T_PLUS:
1069 			sgnd++;
1070 			cn = cn[2];
1071 			goto loop;
1072 		case T_NIL:
1073 			con.cpval = NIL;
1074 			con.cival = 0;
1075 			con.crval = con.cival;
1076 			con.ctype = nl + TNIL;
1077 			break;
1078 		case T_VAR:
1079 			np = lookup(cn[2]);
1080 			if (np == NIL || np->class != CONST) {
1081 				return FALSE;
1082 			}
1083 			if ( cn[3] != NIL ) {
1084 				return FALSE;
1085 			}
1086 			con.ctype = np->type;
1087 			switch (classify(np->type)) {
1088 				case TINT:
1089 					con.crval = np->range[0];
1090 					break;
1091 				case TDOUBLE:
1092 					con.crval = np->real;
1093 					break;
1094 				case TBOOL:
1095 				case TCHAR:
1096 				case TSCAL:
1097 					con.cival = np->value[0];
1098 					con.crval = con.cival;
1099 					break;
1100 				case TSTR:
1101 					con.cpval = np->ptr[0];
1102 					break;
1103 				default:
1104 					con.ctype = NIL;
1105 					return FALSE;
1106 			}
1107 			break;
1108 		case T_BINT:
1109 			con.crval = a8tol(cn[2]);
1110 			goto restcon;
1111 		case T_INT:
1112 			con.crval = atof(cn[2]);
1113 			if (con.crval > MAXINT || con.crval < MININT) {
1114 				derror("Constant too large for this implementation");
1115 				con.crval = 0;
1116 			}
1117 restcon:
1118 			ci = con.crval;
1119 #ifndef PI0
1120 			if (bytes(ci, ci) <= 2)
1121 				con.ctype = nl+T2INT;
1122 			else
1123 #endif
1124 				con.ctype = nl+T4INT;
1125 			break;
1126 		case T_FINT:
1127 			con.ctype = nl+TDOUBLE;
1128 			con.crval = atof(cn[2]);
1129 			break;
1130 		case T_STRNG:
1131 			cp = cn[2];
1132 			if (cp[1] == 0) {
1133 				con.ctype = nl+T1CHAR;
1134 				con.cival = cp[0];
1135 				con.crval = con.cival;
1136 				break;
1137 			}
1138 			con.ctype = nl+TSTR;
1139 			con.cpval = cp;
1140 			break;
1141 	}
1142 	if (sgnd) {
1143 		if (isnta(con.ctype, "id")) {
1144 			derror("%s constants cannot be signed", nameof(con.ctype));
1145 			return FALSE;
1146 		} else if (negd)
1147 			con.crval = -con.crval;
1148 	}
1149 	return TRUE;
1150 }
1151