1 #include "c.h"
2 
3 
4 #define SWSIZE 512
5 
6 #define den(i,j) ((j-buckets[i]+1.0)/(v[j]-v[buckets[i]]+1))
7 
8 struct code codehead = { Start };
9 Code codelist = &codehead;
10 float density = 0.5;
11 Table stmtlabs;
12 
13 static int foldcond(Tree e1, Tree e2);
14 static void caselabel(Swtch, long, int);
15 static void cmp(int, Symbol, long, int);
16 static Tree conditional(int);
17 static void dostmt(int, Swtch, int);
18 static int equal(Symbol, Symbol);
19 static void forstmt(int, Swtch, int);
20 static void ifstmt(int, int, Swtch, int);
21 static Symbol localaddr(Tree);
22 static void stmtlabel(void);
23 static void swstmt(int, int, int);
24 static void whilestmt(int, Swtch, int);
code(int kind)25 Code code(int kind) {
26 	Code cp;
27 
28 	if (!reachable(kind))
29 		warning("unreachable code\n");
30 
31 	NEW(cp, FUNC);
32 	cp->kind = kind;
33 	cp->prev = codelist;
34 	cp->next = NULL;
35 	codelist->next = cp;
36 	codelist = cp;
37 	return cp;
38 }
reachable(int kind)39 int reachable(int kind) {
40 
41 	if (kind > Start) {
42 		Code cp;
43 		for (cp = codelist; cp->kind < Label; )
44 			cp = cp->prev;
45 		if (cp->kind == Jump || cp->kind == Switch)
46 			return 0;
47 	}
48 	return 1;
49 }
addlocal(Symbol p)50 void addlocal(Symbol p) {
51 	if (!p->defined) {
52 		code(Local)->u.var = p;
53 		p->defined = 1;
54 		p->scope = level;
55 	}
56 }
definept(Coordinate * p)57 void definept(Coordinate *p) {
58 	Code cp = code(Defpoint);
59 
60 	cp->u.point.src = p ? *p : src;
61 	cp->u.point.point = npoints;
62 	if (ncalled > 0) {
63 		int n = findcount(cp->u.point.src.file,
64 			cp->u.point.src.x, cp->u.point.src.y);
65 		if (n > 0)
66 			refinc = (float)n/ncalled;
67 	}
68 	if (glevel > 2)	locus(identifiers, &cp->u.point.src);
69 	if (events.points && reachable(Gen))
70 		{
71 			Tree e = NULL;
72 			apply(events.points, &cp->u.point.src, &e);
73 			if (e)
74 				listnodes(e, 0, 0);
75 		}
76 }
statement(int loop,Swtch swp,int lev)77 void statement(int loop, Swtch swp, int lev) {
78 	float ref = refinc;
79 
80 	if (Aflag >= 2 && lev == 15)
81 		warning("more than 15 levels of nested statements\n");
82 	switch (t) {
83 	case IF:       ifstmt(genlabel(2), loop, swp, lev + 1);
84  break;
85 	case WHILE:    whilestmt(genlabel(3), swp, lev + 1); break;
86 	case DO:       dostmt(genlabel(3), swp, lev + 1); expect(';');
87 					break;
88 
89 	case FOR:      forstmt(genlabel(4), swp, lev + 1);
90  break;
91 	case BREAK:    walk(NULL, 0, 0);
92 		       definept(NULL);
93 		       if (swp && swp->lab > loop)
94 		       	branch(swp->lab + 1);
95 		       else if (loop)
96 		       	branch(loop + 2);
97 		       else
98 		       	error("illegal break statement\n");
99 		       t = gettok(); expect(';');
100 					   break;
101 
102 	case CONTINUE: walk(NULL, 0, 0);
103 		       definept(NULL);
104 		       if (loop)
105 		       	branch(loop + 1);
106 		       else
107 		       	error("illegal continue statement\n");
108 		       t = gettok(); expect(';');
109 					      break;
110 
111 	case SWITCH:   swstmt(loop, genlabel(2), lev + 1);
112  break;
113 	case CASE:     {
114 		       	int lab = genlabel(1);
115 		       	if (swp == NULL)
116 		       		error("illegal case label\n");
117 		       	definelab(lab);
118 		       	while (t == CASE) {
119 		       		static char stop[] = { IF, ID, 0 };
120 		       		Tree p;
121 		       		t = gettok();
122 		       		p = constexpr(0);
123 		       		if (generic(p->op) == CNST && isint(p->type)) {
124 		       			if (swp) {
125 		       				needconst++;
126 		       				p = cast(p, swp->sym->type);
127 		       				if (p->type->op == UNSIGNED)
128 		       					p->u.v.i = extend(p->u.v.u, p->type);
129 		       				needconst--;
130 		       				caselabel(swp, p->u.v.i, lab);
131 		       			}
132 		       		} else
133 		       			error("case label must be a constant integer expression\n");
134 
135 		       		test(':', stop);
136 		       	}
137 		       	statement(loop, swp, lev);
138 		       } break;
139 	case DEFAULT:  if (swp == NULL)
140 		       	error("illegal default label\n");
141 		       else if (swp->deflab)
142 		       	error("extra default label\n");
143 		       else {
144 		       	swp->deflab = findlabel(swp->lab);
145 		       	definelab(swp->deflab->u.l.label);
146 		       }
147 		       t = gettok();
148 		       expect(':');
149 		       statement(loop, swp, lev); break;
150 	case RETURN:   {
151 		       	Type rty = freturn(cfunc->type);
152 		       	t = gettok();
153 		       	definept(NULL);
154 		       	if (t != ';')
155 		       		if (rty == voidtype) {
156 		       			error("extraneous return value\n");
157 		       			expr(0);
158 		       			retcode(NULL);
159 		       		} else
160 		       			retcode(expr(0));
161 		       	else {
162 		       		if (rty != voidtype)
163 		       			warning("missing return value\n");
164 		       		retcode(NULL);
165 		       	}
166 		       	branch(cfunc->u.f.label);
167 		       } expect(';');
168 					    break;
169 
170 	case '{':      compound(loop, swp, lev + 1); break;
171 	case ';':      definept(NULL); t = gettok(); break;
172 	case GOTO:     walk(NULL, 0, 0);
173 		       definept(NULL);
174 		       t = gettok();
175 		       if (t == ID) {
176 		       	Symbol p = lookup(token, stmtlabs);
177 		       	if (p == NULL) {
178 				p = install(token, &stmtlabs, 0, FUNC);
179 				p->scope = LABELS;
180 				p->u.l.label = genlabel(1);
181 				p->src = src;
182 			}
183 		       	use(p, src);
184 		       	branch(p->u.l.label);
185 		       	t = gettok();
186 		       } else
187 		       	error("missing label in goto\n"); expect(';');
188 					  break;
189 
190 	case ID:       if (getchr() == ':') {
191 		       	stmtlabel();
192 		       	statement(loop, swp, lev);
193 		       	break;
194 		       }
195 	default:       definept(NULL);
196 		       if (kind[t] != ID) {
197 		       	error("unrecognized statement\n");
198 		       	t = gettok();
199 		       } else {
200 		       	Tree e = expr0(0);
201 		       	listnodes(e, 0, 0);
202 		       	if (nodecount == 0 || nodecount > 200)
203 		       		walk(NULL, 0, 0);
204 		       	else if (glevel) walk(NULL, 0, 0);
205 		       	deallocate(STMT);
206 		       } expect(';');
207 						break;
208 
209 	}
210 	if (kind[t] != IF && kind[t] != ID
211 	&& t != '}' && t != EOI) {
212 		static char stop[] = { IF, ID, '}', 0 };
213 		error("illegal statement termination\n");
214 		skipto(0, stop);
215 	}
216 	refinc = ref;
217 }
218 
ifstmt(int lab,int loop,Swtch swp,int lev)219 static void ifstmt(int lab, int loop, Swtch swp, int lev) {
220 	t = gettok();
221 	expect('(');
222 	definept(NULL);
223 	walk(conditional(')'), 0, lab);
224 	refinc /= 2.0;
225 	statement(loop, swp, lev);
226 	if (t == ELSE) {
227 		branch(lab + 1);
228 		t = gettok();
229 		definelab(lab);
230 		statement(loop, swp, lev);
231 		if (findlabel(lab + 1)->ref)
232 			definelab(lab + 1);
233 	} else
234 		definelab(lab);
235 }
conditional(int tok)236 static Tree conditional(int tok) {
237 	Tree p = expr(tok);
238 
239 	if (Aflag > 1 && isfunc(p->type))
240 		warning("%s used in a conditional expression\n",
241 			funcname(p));
242 	return cond(p);
243 }
stmtlabel(void)244 static void stmtlabel(void) {
245 	Symbol p = lookup(token, stmtlabs);
246 
247 	if (p == NULL) {
248 		p = install(token, &stmtlabs, 0, FUNC);
249 		p->scope = LABELS;
250 		p->u.l.label = genlabel(1);
251 		p->src = src;
252 	}
253 	if (p->defined)
254 		error("redefinition of label `%s' previously defined at %w\n", p->name, &p->src);
255 
256 	p->defined = 1;
257 	definelab(p->u.l.label);
258 	t = gettok();
259 	expect(':');
260 }
forstmt(int lab,Swtch swp,int lev)261 static void forstmt(int lab, Swtch swp, int lev) {
262 	int once = 0;
263 	Tree e1 = NULL, e2 = NULL, e3 = NULL;
264 	Coordinate pt2, pt3;
265 
266 	t = gettok();
267 	expect('(');
268 	definept(NULL);
269 	if (kind[t] == ID)
270 		e1 = texpr(expr0, ';', FUNC);
271 	else
272 		expect(';');
273 	walk(e1, 0, 0);
274 	pt2 = src;
275 	refinc *= 10.0;
276 	if (kind[t] == ID)
277 		e2 = texpr(conditional, ';', FUNC);
278 	else
279 		expect(';');
280 	pt3 = src;
281 	if (kind[t] == ID)
282 		e3 = texpr(expr0, ')', FUNC);
283 	else {
284 		static char stop[] = { IF, ID, '}', 0 };
285 		test(')', stop);
286 	}
287 	if (e2) {
288 		once = foldcond(e1, e2);
289 		if (!once)
290 			branch(lab + 3);
291 	}
292 	definelab(lab);
293 	statement(lab, swp, lev);
294 	definelab(lab + 1);
295 	definept(&pt3);
296 	if (e3)
297 		walk(e3, 0, 0);
298 	if (e2) {
299 		if (!once)
300 			definelab(lab + 3);
301 		definept(&pt2);
302 		walk(e2, lab, 0);
303 	} else {
304 		definept(&pt2);
305 		branch(lab);
306 	}
307 	if (findlabel(lab + 2)->ref)
308 		definelab(lab + 2);
309 }
swstmt(int loop,int lab,int lev)310 static void swstmt(int loop, int lab, int lev) {
311 	Tree e;
312 	struct swtch sw;
313 	Code head, tail;
314 
315 	t = gettok();
316 	expect('(');
317 	definept(NULL);
318 	e = expr(')');
319 	if (!isint(e->type)) {
320 		error("illegal type `%t' in switch expression\n",
321 			e->type);
322 		e = retype(e, inttype);
323 	}
324 	e = cast(e, promote(e->type));
325 	if (generic(e->op) == INDIR && isaddrop(e->kids[0]->op)
326 	&& e->kids[0]->u.sym->type == e->type
327 	&& !isvolatile(e->kids[0]->u.sym->type)) {
328 		sw.sym = e->kids[0]->u.sym;
329 		walk(NULL, 0, 0);
330 	} else {
331 		sw.sym = genident(REGISTER, e->type, level);
332 		addlocal(sw.sym);
333 		walk(asgn(sw.sym, e), 0, 0);
334 	}
335 	head = code(Switch);
336 	sw.lab = lab;
337 	sw.deflab = NULL;
338 	sw.ncases = 0;
339 	sw.size = SWSIZE;
340 	sw.values = newarray(SWSIZE, sizeof *sw.values, FUNC);
341 	sw.labels = newarray(SWSIZE, sizeof *sw.labels, FUNC);
342 	refinc /= 10.0;
343 	statement(loop, &sw, lev);
344 	if (sw.deflab == NULL) {
345 		sw.deflab = findlabel(lab);
346 		definelab(lab);
347 		if (sw.ncases == 0)
348 			warning("switch statement with no cases\n");
349 	}
350 	if (findlabel(lab + 1)->ref)
351 		definelab(lab + 1);
352 	tail = codelist;
353 	codelist = head->prev;
354 	codelist->next = head->prev = NULL;
355 	if (sw.ncases > 0)
356 		swgen(&sw);
357 	branch(lab);
358 	head->next->prev = codelist;
359 	codelist->next = head->next;
360 	codelist = tail;
361 }
caselabel(Swtch swp,long val,int lab)362 static void caselabel(Swtch swp, long val, int lab) {
363 	int k;
364 
365 	if (swp->ncases >= swp->size)
366 		{
367 		long   *vals = swp->values;
368 		Symbol *labs = swp->labels;
369 		swp->size *= 2;
370 		swp->values = newarray(swp->size, sizeof *swp->values, FUNC);
371 		swp->labels = newarray(swp->size, sizeof *swp->labels, FUNC);
372 		for (k = 0; k < swp->ncases; k++) {
373 			swp->values[k] = vals[k];
374 			swp->labels[k] = labs[k];
375 		}
376 		}
377 	k = swp->ncases;
378 	for ( ; k > 0 && swp->values[k-1] >= val; k--) {
379 		swp->values[k] = swp->values[k-1];
380 		swp->labels[k] = swp->labels[k-1];
381 	}
382 	if (k < swp->ncases && swp->values[k] == val)
383 		error("duplicate case label `%d'\n", val);
384 	swp->values[k] = val;
385 	swp->labels[k] = findlabel(lab);
386 	++swp->ncases;
387 	if (Aflag >= 2 && swp->ncases == 258)
388 		warning("more than 257 cases in a switch\n");
389 }
swgen(Swtch swp)390 void swgen(Swtch swp) {
391 	int *buckets, k, n;
392 	long *v = swp->values;
393 
394 	buckets = newarray(swp->ncases + 1,
395 		sizeof *buckets, FUNC);
396 	for (n = k = 0; k < swp->ncases; k++, n++) {
397 		buckets[n] = k;
398 		while (n > 0 && den(n-1, k) >= density)
399 			n--;
400 	}
401 	buckets[n] = swp->ncases;
402 	swcode(swp, buckets, 0, n - 1);
403 }
swcode(Swtch swp,int b[],int lb,int ub)404 void swcode(Swtch swp, int b[], int lb, int ub) {
405 	int hilab, lolab, l, u, k = (lb + ub)/2;
406 	long *v = swp->values;
407 
408 	if (k > lb && k < ub) {
409 		lolab = genlabel(1);
410 		hilab = genlabel(1);
411 	} else if (k > lb) {
412 		lolab = genlabel(1);
413 		hilab = swp->deflab->u.l.label;
414 	} else if (k < ub) {
415 		lolab = swp->deflab->u.l.label;
416 		hilab = genlabel(1);
417 	} else
418 		lolab = hilab = swp->deflab->u.l.label;
419 	l = b[k];
420 	u = b[k+1] - 1;
421 	if (u - l + 1 <= 3)
422 		{
423 			int i;
424 			for (i = l; i <= u; i++)
425 				cmp(EQ, swp->sym, v[i], swp->labels[i]->u.l.label);
426 			if (k > lb && k < ub)
427 				cmp(GT, swp->sym, v[u], hilab);
428 			else if (k > lb)
429 				cmp(GT, swp->sym, v[u], hilab);
430 			else if (k < ub)
431 				cmp(LT, swp->sym, v[l], lolab);
432 			else
433 				assert(lolab == hilab),
434 				branch(lolab);
435 			walk(NULL, 0, 0);
436 		}
437 	else {
438 		Tree e;
439 		Type ty = signedint(swp->sym->type);
440 		Symbol table = genident(STATIC,
441 			array(voidptype, u - l + 1, 0), GLOBAL);
442 		(*IR->defsymbol)(table);
443 		if (!isunsigned(swp->sym->type) || v[l] != 0)
444 			cmp(LT, swp->sym, v[l], lolab);
445 		cmp(GT, swp->sym, v[u], hilab);
446 		e = (*optree['-'])(SUB, cast(idtree(swp->sym), ty), cnsttree(ty, v[l]));
447 		if (e->type->size < unsignedptr->size)
448 			e = cast(e, unsignedlong);
449 		walk(tree(JUMP, voidtype,
450 			rvalue((*optree['+'])(ADD, pointer(idtree(table)), e)), NULL),
451 			0, 0);
452 		code(Switch);
453 		codelist->u.swtch.table = table;
454 		codelist->u.swtch.sym = swp->sym;
455 		codelist->u.swtch.deflab = swp->deflab;
456 		codelist->u.swtch.size = u - l + 1;
457 		codelist->u.swtch.values = &v[l];
458 		codelist->u.swtch.labels = &swp->labels[l];
459 		if (v[u] - v[l] + 1 >= 10000)
460 			warning("switch generates a huge table\n");
461 	}
462 	if (k > lb) {
463 		assert(lolab != swp->deflab->u.l.label);
464 		definelab(lolab);
465 		swcode(swp, b, lb, k - 1);
466 	}
467 	if (k < ub) {
468 		assert(hilab != swp->deflab->u.l.label);
469 		definelab(hilab);
470 		swcode(swp, b, k + 1, ub);
471 	}
472 }
cmp(int op,Symbol p,long n,int lab)473 static void cmp(int op, Symbol p, long n, int lab) {
474 	Type ty = signedint(p->type);
475 
476 	listnodes(eqtree(op,
477 			cast(idtree(p), ty),
478 			cnsttree(ty, n)),
479 		lab, 0);
480 }
retcode(Tree p)481 void retcode(Tree p) {
482 	Type ty;
483 
484 	if (p == NULL) {
485 		if (events.returns)
486 			apply(events.returns, cfunc, NULL);
487 		return;
488 	}
489 	p = pointer(p);
490 	ty = assign(freturn(cfunc->type), p);
491 	if (ty == NULL) {
492 		error("illegal return type; found `%t' expected `%t'\n",
493 			p->type, freturn(cfunc->type));
494 		return;
495 	}
496 	p = cast(p, ty);
497 	if (retv)
498 		{
499 			if (iscallb(p))
500 				p = tree(RIGHT, p->type,
501 					tree(CALL+B, p->type,
502 						p->kids[0]->kids[0], idtree(retv)),
503 					rvalue(idtree(retv)));
504 			else
505 				p = asgntree(ASGN, rvalue(idtree(retv)), p);
506 			walk(p, 0, 0);
507 			if (events.returns)
508 				apply(events.returns, cfunc, rvalue(idtree(retv)));
509 			return;
510 		}
511 	if (events.returns)
512 		{
513 			Symbol t1 = genident(AUTO, p->type, level);
514 			addlocal(t1);
515 			walk(asgn(t1, p), 0, 0);
516 			apply(events.returns, cfunc, idtree(t1));
517 			p = idtree(t1);
518 		}
519 	if (!isfloat(p->type))
520 		p = cast(p, promote(p->type));
521 	if (isptr(p->type))
522 		{
523 			Symbol q = localaddr(p);
524 			if (q && (q->computed || q->generated))
525 				warning("pointer to a %s is an illegal return value\n",
526 					q->scope == PARAM ? "parameter" : "local");
527 			else if (q)
528 				warning("pointer to %s `%s' is an illegal return value\n",
529 					q->scope == PARAM ? "parameter" : "local", q->name);
530 		}
531 	walk(tree(mkop(RET,p->type), p->type, p, NULL), 0, 0);
532 }
definelab(int lab)533 void definelab(int lab) {
534 	Code cp;
535 	Symbol p = findlabel(lab);
536 
537 	assert(lab);
538 	walk(NULL, 0, 0);
539 	code(Label)->u.forest = newnode(LABEL+V, NULL, NULL, p);
540 	for (cp = codelist->prev; cp->kind <= Label; )
541 		cp = cp->prev;
542 	while (   cp->kind == Jump
543 	       && cp->u.forest->kids[0]
544 	       && specific(cp->u.forest->kids[0]->op) == ADDRG+P
545 	       && cp->u.forest->kids[0]->syms[0] == p) {
546 		assert(cp->u.forest->kids[0]->syms[0]->u.l.label == lab);
547 		p->ref--;
548 		assert(cp->next);
549 		assert(cp->prev);
550 		cp->prev->next = cp->next;
551 		cp->next->prev = cp->prev;
552 		cp = cp->prev;
553 		while (cp->kind <= Label)
554 			cp = cp->prev;
555 	}
556 }
jump(int lab)557 Node jump(int lab) {
558 	Symbol p = findlabel(lab);
559 
560 	p->ref++;
561 	return newnode(JUMP+V, newnode(ADDRG+ttob(voidptype), NULL, NULL, p),
562 		NULL, NULL);
563 }
branch(int lab)564 void branch(int lab) {
565 	Code cp;
566 	Symbol p = findlabel(lab);
567 
568 	assert(lab);
569 	walk(NULL, 0, 0);
570 	code(Label)->u.forest = jump(lab);
571 	for (cp = codelist->prev; cp->kind < Label; )
572 		cp = cp->prev;
573 	while (   cp->kind == Label
574 	       && cp->u.forest->op == LABEL+V
575 	       && !equal(cp->u.forest->syms[0], p)) {
576 		equatelab(cp->u.forest->syms[0], p);
577 		assert(cp->next);
578 		assert(cp->prev);
579 		cp->prev->next = cp->next;
580 		cp->next->prev = cp->prev;
581 		cp = cp->prev;
582 		while (cp->kind < Label)
583 			cp = cp->prev;
584 	}
585 	if (cp->kind == Jump || cp->kind == Switch) {
586 		p->ref--;
587 		codelist->prev->next = NULL;
588 		codelist = codelist->prev;
589 	} else {
590 		codelist->kind = Jump;
591 		if (cp->kind == Label
592 		&&  cp->u.forest->op == LABEL+V
593 		&&  equal(cp->u.forest->syms[0], p))
594 			warning("source code specifies an infinite loop");
595 	}
596 }
equatelab(Symbol old,Symbol new)597 void equatelab(Symbol old, Symbol new) {
598 	assert(old->u.l.equatedto == NULL);
599 	old->u.l.equatedto = new;
600 	new->ref++;
601 }
equal(Symbol lprime,Symbol dst)602 static int equal(Symbol lprime, Symbol dst) {
603 	assert(dst && lprime);
604 	for ( ; dst; dst = dst->u.l.equatedto)
605 		if (lprime == dst)
606 			return 1;
607 	return 0;
608 }
609 /* dostmt - do statement while ( expression ) */
dostmt(int lab,Swtch swp,int lev)610 static void dostmt(int lab, Swtch swp, int lev) {
611 	refinc *= 10.0;
612 	t = gettok();
613 	definelab(lab);
614 	statement(lab, swp, lev);
615 	definelab(lab + 1);
616 	expect(WHILE);
617 	expect('(');
618 	definept(NULL);
619 	walk(conditional(')'), lab, 0);
620 	if (findlabel(lab + 2)->ref)
621 		definelab(lab + 2);
622 }
623 
624 /* foldcond - check if initial test in for(e1;e2;e3) S is necessary */
foldcond(Tree e1,Tree e2)625 static int foldcond(Tree e1, Tree e2) {
626 	int op = generic(e2->op);
627 	Symbol v;
628 
629 	if (e1 == 0 || e2 == 0)
630 		return 0;
631 	if (generic(e1->op) == ASGN && isaddrop(e1->kids[0]->op)
632 	&& generic(e1->kids[1]->op) == CNST) {
633 		v = e1->kids[0]->u.sym;
634 		e1 = e1->kids[1];
635 	} else
636 		return 0;
637 	if ((op==LE || op==LT || op==EQ || op==NE || op==GT || op==GE)
638 	&& generic(e2->kids[0]->op) == INDIR
639 	&& e2->kids[0]->kids[0]->u.sym == v
640 	&& e2->kids[1]->op == e1->op) {
641 		e1 = simplify(op, e2->type, e1, e2->kids[1]);
642 		if (e1->op == CNST+I)
643 			return e1->u.v.i;
644 	}
645 	return 0;
646 }
647 
648 /* localaddr - returns q if p yields the address of local/parameter q; otherwise returns 0 */
localaddr(Tree p)649 static Symbol localaddr(Tree p) {
650 	if (p == NULL)
651 		return NULL;
652 	switch (generic(p->op)) {
653 	case INDIR: case CALL: case ARG:
654 		return NULL;
655 	case ADDRL: case ADDRF:
656 		return p->u.sym;
657 	case RIGHT: case ASGN:
658 		if (p->kids[1])
659 			return localaddr(p->kids[1]);
660 		return localaddr(p->kids[0]);
661 	case COND: {
662 		Symbol q;
663 		assert(p->kids[1] && p->kids[1]->op == RIGHT);
664 		if ((q = localaddr(p->kids[1]->kids[0])) != NULL)
665 			return q;
666 		return localaddr(p->kids[1]->kids[1]);
667 		}
668 	default: {
669 		Symbol q;
670 		if (p->kids[0] && (q = localaddr(p->kids[0])) != NULL)
671 			return q;
672 		return localaddr(p->kids[1]);
673 		}
674 	}
675 }
676 
677 /* whilestmt - while ( expression ) statement */
whilestmt(int lab,Swtch swp,int lev)678 static void whilestmt(int lab, Swtch swp, int lev) {
679 	Coordinate pt;
680 	Tree e;
681 
682 	refinc *= 10.0;
683 	t = gettok();
684 	expect('(');
685 	walk(NULL, 0, 0);
686 	pt = src;
687 	e = texpr(conditional, ')', FUNC);
688 	branch(lab + 1);
689 	definelab(lab);
690 	statement(lab, swp, lev);
691 	definelab(lab + 1);
692 	definept(&pt);
693 	walk(e, lab, 0);
694 	if (findlabel(lab + 2)->ref)
695 		definelab(lab + 2);
696 }
697