1/*
2 * DFA routines
3 * This file is #included by regexec.c.
4 *
5 * Copyright (c) 1998, 1999 Henry Spencer.  All rights reserved.
6 *
7 * Development of this software was funded, in part, by Cray Research Inc.,
8 * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
9 * Corporation, none of whom are responsible for the results.  The author
10 * thanks all of them.
11 *
12 * Redistribution and use in source and binary forms -- with or without
13 * modification -- are permitted for any purpose, provided that
14 * redistributions in source form retain this entire copyright notice and
15 * indicate the origin and nature of any modifications.
16 *
17 * I'd appreciate being given credit for this package in the documentation
18 * of software which uses it, but that is not a requirement.
19 *
20 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
21 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
22 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
23 * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
26 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
27 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
28 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
29 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 *
31 */
32
33/*
34 - longest - longest-preferred matching engine
35 ^ static chr *longest(struct vars *, struct dfa *, chr *, chr *, int *);
36 */
37static chr *			/* endpoint, or NULL */
38longest(v, d, start, stop, hitstopp)
39struct vars *v;			/* used only for debug and exec flags */
40struct dfa *d;
41chr *start;			/* where the match should start */
42chr *stop;			/* match must end at or before here */
43int *hitstopp;			/* record whether hit v->stop, if non-NULL */
44{
45	chr *cp;
46	chr *realstop = (stop == v->stop) ? stop : stop + 1;
47	color co;
48	struct sset *css;
49	struct sset *ss;
50	chr *post;
51	int i;
52	struct colormap *cm = d->cm;
53
54	/* initialize */
55	css = initialize(v, d, start);
56	cp = start;
57	if (hitstopp != NULL)
58		*hitstopp = 0;
59
60	/* startup */
61	FDEBUG(("+++ startup +++\n"));
62	if (cp == v->start) {
63		co = d->cnfa->bos[(v->eflags&REG_NOTBOL) ? 0 : 1];
64		FDEBUG(("color %ld\n", (long)co));
65	} else {
66		co = GETCOLOR(cm, *(cp - 1));
67		FDEBUG(("char %c, color %ld\n", (char)*(cp-1), (long)co));
68	}
69	css = miss(v, d, css, co, cp, start);
70	if (css == NULL)
71		return NULL;
72	css->lastseen = cp;
73
74	/* main loop */
75	if (v->eflags&REG_FTRACE)
76		while (cp < realstop) {
77			FDEBUG(("+++ at c%d +++\n", css - d->ssets));
78			co = GETCOLOR(cm, *cp);
79			FDEBUG(("char %c, color %ld\n", (char)*cp, (long)co));
80			ss = css->outs[co];
81			if (ss == NULL) {
82				ss = miss(v, d, css, co, cp+1, start);
83				if (ss == NULL)
84					break;	/* NOTE BREAK OUT */
85			}
86			cp++;
87			ss->lastseen = cp;
88			css = ss;
89		}
90	else
91		while (cp < realstop) {
92			co = GETCOLOR(cm, *cp);
93			ss = css->outs[co];
94			if (ss == NULL) {
95				ss = miss(v, d, css, co, cp+1, start);
96				if (ss == NULL)
97					break;	/* NOTE BREAK OUT */
98			}
99			cp++;
100			ss->lastseen = cp;
101			css = ss;
102		}
103
104	/* shutdown */
105	FDEBUG(("+++ shutdown at c%d +++\n", css - d->ssets));
106	if (cp == v->stop && stop == v->stop) {
107		if (hitstopp != NULL)
108			*hitstopp = 1;
109		co = d->cnfa->eos[(v->eflags&REG_NOTEOL) ? 0 : 1];
110		FDEBUG(("color %ld\n", (long)co));
111		ss = miss(v, d, css, co, cp, start);
112		/* special case:  match ended at eol? */
113		if (ss != NULL && (ss->flags&POSTSTATE))
114			return cp;
115		else if (ss != NULL)
116			ss->lastseen = cp;	/* to be tidy */
117	}
118
119	/* find last match, if any */
120	post = d->lastpost;
121	for (ss = d->ssets, i = d->nssused; i > 0; ss++, i--)
122		if ((ss->flags&POSTSTATE) && post != ss->lastseen &&
123					(post == NULL || post < ss->lastseen))
124			post = ss->lastseen;
125	if (post != NULL)		/* found one */
126		return post - 1;
127
128	return NULL;
129}
130
131/*
132 - shortest - shortest-preferred matching engine
133 ^ static chr *shortest(struct vars *, struct dfa *, chr *, chr *, chr *,
134 ^ 	chr **, int *);
135 */
136static chr *			/* endpoint, or NULL */
137shortest(v, d, start, min, max, coldp, hitstopp)
138struct vars *v;
139struct dfa *d;
140chr *start;			/* where the match should start */
141chr *min;			/* match must end at or after here */
142chr *max;			/* match must end at or before here */
143chr **coldp;			/* store coldstart pointer here, if nonNULL */
144int *hitstopp;			/* record whether hit v->stop, if non-NULL */
145{
146	chr *cp;
147	chr *realmin = (min == v->stop) ? min : min + 1;
148	chr *realmax = (max == v->stop) ? max : max + 1;
149	color co;
150	struct sset *css;
151	struct sset *ss;
152	struct colormap *cm = d->cm;
153
154	/* initialize */
155	css = initialize(v, d, start);
156	cp = start;
157	if (hitstopp != NULL)
158		*hitstopp = 0;
159
160	/* startup */
161	FDEBUG(("--- startup ---\n"));
162	if (cp == v->start) {
163		co = d->cnfa->bos[(v->eflags&REG_NOTBOL) ? 0 : 1];
164		FDEBUG(("color %ld\n", (long)co));
165	} else {
166		co = GETCOLOR(cm, *(cp - 1));
167		FDEBUG(("char %c, color %ld\n", (char)*(cp-1), (long)co));
168	}
169	css = miss(v, d, css, co, cp, start);
170	if (css == NULL)
171		return NULL;
172	css->lastseen = cp;
173	ss = css;
174
175	/* main loop */
176	if (v->eflags&REG_FTRACE)
177		while (cp < realmax) {
178			FDEBUG(("--- at c%d ---\n", css - d->ssets));
179			co = GETCOLOR(cm, *cp);
180			FDEBUG(("char %c, color %ld\n", (char)*cp, (long)co));
181			ss = css->outs[co];
182			if (ss == NULL) {
183				ss = miss(v, d, css, co, cp+1, start);
184				if (ss == NULL)
185					break;	/* NOTE BREAK OUT */
186			}
187			cp++;
188			ss->lastseen = cp;
189			css = ss;
190			if ((ss->flags&POSTSTATE) && cp >= realmin)
191				break;		/* NOTE BREAK OUT */
192		}
193	else
194		while (cp < realmax) {
195			co = GETCOLOR(cm, *cp);
196			ss = css->outs[co];
197			if (ss == NULL) {
198				ss = miss(v, d, css, co, cp+1, start);
199				if (ss == NULL)
200					break;	/* NOTE BREAK OUT */
201			}
202			cp++;
203			ss->lastseen = cp;
204			css = ss;
205			if ((ss->flags&POSTSTATE) && cp >= realmin)
206				break;		/* NOTE BREAK OUT */
207		}
208
209	if (ss == NULL)
210		return NULL;
211
212	if (coldp != NULL)	/* report last no-progress state set, if any */
213		*coldp = lastcold(v, d);
214
215	if ((ss->flags&POSTSTATE) && cp > min) {
216		assert(cp >= realmin);
217		cp--;
218	} else if (cp == v->stop && max == v->stop) {
219		co = d->cnfa->eos[(v->eflags&REG_NOTEOL) ? 0 : 1];
220		FDEBUG(("color %ld\n", (long)co));
221		ss = miss(v, d, css, co, cp, start);
222		/* match might have ended at eol */
223		if ((ss == NULL || !(ss->flags&POSTSTATE)) && hitstopp != NULL)
224			*hitstopp = 1;
225	}
226
227	if (ss == NULL || !(ss->flags&POSTSTATE))
228		return NULL;
229
230	return cp;
231}
232
233/*
234 - lastcold - determine last point at which no progress had been made
235 ^ static chr *lastcold(struct vars *, struct dfa *);
236 */
237static chr *			/* endpoint, or NULL */
238lastcold(v, d)
239struct vars *v;
240struct dfa *d;
241{
242	struct sset *ss;
243	chr *nopr;
244	int i;
245
246	nopr = d->lastnopr;
247	if (nopr == NULL)
248		nopr = v->start;
249	for (ss = d->ssets, i = d->nssused; i > 0; ss++, i--)
250		if ((ss->flags&NOPROGRESS) && nopr < ss->lastseen)
251			nopr = ss->lastseen;
252	return nopr;
253}
254
255/*
256 - newdfa - set up a fresh DFA
257 ^ static struct dfa *newdfa(struct vars *, struct cnfa *,
258 ^ 	struct colormap *, struct smalldfa *);
259 */
260static struct dfa *
261newdfa(v, cnfa, cm, small)
262struct vars *v;
263struct cnfa *cnfa;
264struct colormap *cm;
265struct smalldfa *small;		/* preallocated space, may be NULL */
266{
267	struct dfa *d;
268	size_t nss = cnfa->nstates * 2;
269	int wordsper = (cnfa->nstates + UBITS - 1) / UBITS;
270	struct smalldfa *smallwas = small;
271
272	assert(cnfa != NULL && cnfa->nstates != 0);
273
274	if (nss <= FEWSTATES && cnfa->ncolors <= FEWCOLORS) {
275		assert(wordsper == 1);
276		if (small == NULL) {
277			small = (struct smalldfa *)MALLOC(
278						sizeof(struct smalldfa));
279			if (small == NULL) {
280				ERR(REG_ESPACE);
281				return NULL;
282			}
283		}
284		d = &small->dfa;
285		d->ssets = small->ssets;
286		d->statesarea = small->statesarea;
287		d->work = &d->statesarea[nss];
288		d->outsarea = small->outsarea;
289		d->incarea = small->incarea;
290		d->cptsmalloced = 0;
291		d->mallocarea = (smallwas == NULL) ? (char *)small : NULL;
292	} else {
293		d = (struct dfa *)MALLOC(sizeof(struct dfa));
294		if (d == NULL) {
295			ERR(REG_ESPACE);
296			return NULL;
297		}
298		d->ssets = (struct sset *)MALLOC(nss * sizeof(struct sset));
299		d->statesarea = (unsigned *)MALLOC((nss+WORK) * wordsper *
300							sizeof(unsigned));
301		d->work = &d->statesarea[nss * wordsper];
302		d->outsarea = (struct sset **)MALLOC(nss * cnfa->ncolors *
303							sizeof(struct sset *));
304		d->incarea = (struct arcp *)MALLOC(nss * cnfa->ncolors *
305							sizeof(struct arcp));
306		d->cptsmalloced = 1;
307		d->mallocarea = (char *)d;
308		if (d->ssets == NULL || d->statesarea == NULL ||
309				d->outsarea == NULL || d->incarea == NULL) {
310			freedfa(d);
311			ERR(REG_ESPACE);
312			return NULL;
313		}
314	}
315
316	d->nssets = (v->eflags&REG_SMALL) ? 7 : nss;
317	d->nssused = 0;
318	d->nstates = cnfa->nstates;
319	d->ncolors = cnfa->ncolors;
320	d->wordsper = wordsper;
321	d->cnfa = cnfa;
322	d->cm = cm;
323	d->lastpost = NULL;
324	d->lastnopr = NULL;
325	d->search = d->ssets;
326
327	/* initialization of sset fields is done as needed */
328
329	return d;
330}
331
332/*
333 - freedfa - free a DFA
334 ^ static VOID freedfa(struct dfa *);
335 */
336static VOID
337freedfa(d)
338struct dfa *d;
339{
340	if (d->cptsmalloced) {
341		if (d->ssets != NULL)
342			FREE(d->ssets);
343		if (d->statesarea != NULL)
344			FREE(d->statesarea);
345		if (d->outsarea != NULL)
346			FREE(d->outsarea);
347		if (d->incarea != NULL)
348			FREE(d->incarea);
349	}
350
351	if (d->mallocarea != NULL)
352		FREE(d->mallocarea);
353}
354
355/*
356 - hash - construct a hash code for a bitvector
357 * There are probably better ways, but they're more expensive.
358 ^ static unsigned hash(unsigned *, int);
359 */
360static unsigned
361hash(uv, n)
362unsigned *uv;
363int n;
364{
365	int i;
366	unsigned h;
367
368	h = 0;
369	for (i = 0; i < n; i++)
370		h ^= uv[i];
371	return h;
372}
373
374/*
375 - initialize - hand-craft a cache entry for startup, otherwise get ready
376 ^ static struct sset *initialize(struct vars *, struct dfa *, chr *);
377 */
378static struct sset *
379initialize(v, d, start)
380struct vars *v;			/* used only for debug flags */
381struct dfa *d;
382chr *start;
383{
384	struct sset *ss;
385	int i;
386
387	/* is previous one still there? */
388	if (d->nssused > 0 && (d->ssets[0].flags&STARTER))
389		ss = &d->ssets[0];
390	else {				/* no, must (re)build it */
391		ss = getvacant(v, d, start, start);
392		for (i = 0; i < d->wordsper; i++)
393			ss->states[i] = 0;
394		BSET(ss->states, d->cnfa->pre);
395		ss->hash = HASH(ss->states, d->wordsper);
396		assert(d->cnfa->pre != d->cnfa->post);
397		ss->flags = STARTER|LOCKED|NOPROGRESS;
398		/* lastseen dealt with below */
399	}
400
401	for (i = 0; i < d->nssused; i++)
402		d->ssets[i].lastseen = NULL;
403	ss->lastseen = start;		/* maybe untrue, but harmless */
404	d->lastpost = NULL;
405	d->lastnopr = NULL;
406	return ss;
407}
408
409/*
410 - miss - handle a cache miss
411 ^ static struct sset *miss(struct vars *, struct dfa *, struct sset *,
412 ^ 	pcolor, chr *, chr *);
413 */
414static struct sset *		/* NULL if goes to empty set */
415miss(v, d, css, co, cp, start)
416struct vars *v;			/* used only for debug flags */
417struct dfa *d;
418struct sset *css;
419pcolor co;
420chr *cp;			/* next chr */
421chr *start;			/* where the attempt got started */
422{
423	struct cnfa *cnfa = d->cnfa;
424	int i;
425	unsigned h;
426	struct carc *ca;
427	struct sset *p;
428	int ispost;
429	int noprogress;
430	int gotstate;
431	int dolacons;
432	int sawlacons;
433
434	/* for convenience, we can be called even if it might not be a miss */
435	if (css->outs[co] != NULL) {
436		FDEBUG(("hit\n"));
437		return css->outs[co];
438	}
439	FDEBUG(("miss\n"));
440
441	/* first, what set of states would we end up in? */
442	for (i = 0; i < d->wordsper; i++)
443		d->work[i] = 0;
444	ispost = 0;
445	noprogress = 1;
446	gotstate = 0;
447	for (i = 0; i < d->nstates; i++)
448		if (ISBSET(css->states, i))
449			for (ca = cnfa->states[i]+1; ca->co != COLORLESS; ca++)
450				if (ca->co == co) {
451					BSET(d->work, ca->to);
452					gotstate = 1;
453					if (ca->to == cnfa->post)
454						ispost = 1;
455					if (!cnfa->states[ca->to]->co)
456						noprogress = 0;
457					FDEBUG(("%d -> %d\n", i, ca->to));
458				}
459	dolacons = (gotstate) ? (cnfa->flags&HASLACONS) : 0;
460	sawlacons = 0;
461	while (dolacons) {		/* transitive closure */
462		dolacons = 0;
463		for (i = 0; i < d->nstates; i++)
464			if (ISBSET(d->work, i))
465				for (ca = cnfa->states[i]+1; ca->co != COLORLESS;
466									ca++) {
467					if (ca->co <= cnfa->ncolors)
468						continue; /* NOTE CONTINUE */
469					sawlacons = 1;
470					if (ISBSET(d->work, ca->to))
471						continue; /* NOTE CONTINUE */
472					if (!lacon(v, cnfa, cp, ca->co))
473						continue; /* NOTE CONTINUE */
474					BSET(d->work, ca->to);
475					dolacons = 1;
476					if (ca->to == cnfa->post)
477						ispost = 1;
478					if (!cnfa->states[ca->to]->co)
479						noprogress = 0;
480					FDEBUG(("%d :> %d\n", i, ca->to));
481				}
482	}
483	if (!gotstate)
484		return NULL;
485	h = HASH(d->work, d->wordsper);
486
487	/* next, is that in the cache? */
488	for (p = d->ssets, i = d->nssused; i > 0; p++, i--)
489		if (HIT(h, d->work, p, d->wordsper)) {
490			FDEBUG(("cached c%d\n", p - d->ssets));
491			break;			/* NOTE BREAK OUT */
492		}
493	if (i == 0) {		/* nope, need a new cache entry */
494		p = getvacant(v, d, cp, start);
495		assert(p != css);
496		for (i = 0; i < d->wordsper; i++)
497			p->states[i] = d->work[i];
498		p->hash = h;
499		p->flags = (ispost) ? POSTSTATE : 0;
500		if (noprogress)
501			p->flags |= NOPROGRESS;
502		/* lastseen to be dealt with by caller */
503	}
504
505	if (!sawlacons) {		/* lookahead conds. always cache miss */
506		FDEBUG(("c%d[%d]->c%d\n", css - d->ssets, co, p - d->ssets));
507		css->outs[co] = p;
508		css->inchain[co] = p->ins;
509		p->ins.ss = css;
510		p->ins.co = (color)co;
511	}
512	return p;
513}
514
515/*
516 - lacon - lookahead-constraint checker for miss()
517 ^ static int lacon(struct vars *, struct cnfa *, chr *, pcolor);
518 */
519static int			/* predicate:  constraint satisfied? */
520lacon(v, pcnfa, cp, co)
521struct vars *v;
522struct cnfa *pcnfa;		/* parent cnfa */
523chr *cp;
524pcolor co;			/* "color" of the lookahead constraint */
525{
526	int n;
527	struct subre *sub;
528	struct dfa *d;
529	struct smalldfa sd;
530	chr *end;
531
532	n = co - pcnfa->ncolors;
533	assert(n < v->g->nlacons && v->g->lacons != NULL);
534	FDEBUG(("=== testing lacon %d\n", n));
535	sub = &v->g->lacons[n];
536	d = newdfa(v, &sub->cnfa, &v->g->cmap, &sd);
537	if (d == NULL) {
538		ERR(REG_ESPACE);
539		return 0;
540	}
541	end = longest(v, d, cp, v->stop, (int *)NULL);
542	freedfa(d);
543	FDEBUG(("=== lacon %d match %d\n", n, (end != NULL)));
544	return (sub->subno) ? (end != NULL) : (end == NULL);
545}
546
547/*
548 - getvacant - get a vacant state set
549 * This routine clears out the inarcs and outarcs, but does not otherwise
550 * clear the innards of the state set -- that's up to the caller.
551 ^ static struct sset *getvacant(struct vars *, struct dfa *, chr *, chr *);
552 */
553static struct sset *
554getvacant(v, d, cp, start)
555struct vars *v;			/* used only for debug flags */
556struct dfa *d;
557chr *cp;
558chr *start;
559{
560	int i;
561	struct sset *ss;
562	struct sset *p;
563	struct arcp ap;
564	struct arcp lastap = {NULL, 0}; /* silence gcc 4 warning */
565	color co;
566
567	ss = pickss(v, d, cp, start);
568	assert(!(ss->flags&LOCKED));
569
570	/* clear out its inarcs, including self-referential ones */
571	ap = ss->ins;
572	while ((p = ap.ss) != NULL) {
573		co = ap.co;
574		FDEBUG(("zapping c%d's %ld outarc\n", p - d->ssets, (long)co));
575		p->outs[co] = NULL;
576		ap = p->inchain[co];
577		p->inchain[co].ss = NULL;	/* paranoia */
578	}
579	ss->ins.ss = NULL;
580
581	/* take it off the inarc chains of the ssets reached by its outarcs */
582	for (i = 0; i < d->ncolors; i++) {
583		p = ss->outs[i];
584		assert(p != ss);		/* not self-referential */
585		if (p == NULL)
586			continue;		/* NOTE CONTINUE */
587		FDEBUG(("del outarc %d from c%d's in chn\n", i, p - d->ssets));
588		if (p->ins.ss == ss && p->ins.co == i)
589			p->ins = ss->inchain[i];
590		else {
591			assert(p->ins.ss != NULL);
592			for (ap = p->ins; ap.ss != NULL &&
593						!(ap.ss == ss && ap.co == i);
594						ap = ap.ss->inchain[ap.co])
595				lastap = ap;
596			assert(ap.ss != NULL);
597			lastap.ss->inchain[lastap.co] = ss->inchain[i];
598		}
599		ss->outs[i] = NULL;
600		ss->inchain[i].ss = NULL;
601	}
602
603	/* if ss was a success state, may need to remember location */
604	if ((ss->flags&POSTSTATE) && ss->lastseen != d->lastpost &&
605			(d->lastpost == NULL || d->lastpost < ss->lastseen))
606		d->lastpost = ss->lastseen;
607
608	/* likewise for a no-progress state */
609	if ((ss->flags&NOPROGRESS) && ss->lastseen != d->lastnopr &&
610			(d->lastnopr == NULL || d->lastnopr < ss->lastseen))
611		d->lastnopr = ss->lastseen;
612
613	return ss;
614}
615
616/*
617 - pickss - pick the next stateset to be used
618 ^ static struct sset *pickss(struct vars *, struct dfa *, chr *, chr *);
619 */
620static struct sset *
621pickss(v, d, cp, start)
622struct vars *v;			/* used only for debug flags */
623struct dfa *d;
624chr *cp;
625chr *start;
626{
627	int i;
628	struct sset *ss;
629	struct sset *end;
630	chr *ancient;
631
632	/* shortcut for cases where cache isn't full */
633	if (d->nssused < d->nssets) {
634		i = d->nssused;
635		d->nssused++;
636		ss = &d->ssets[i];
637		FDEBUG(("new c%d\n", i));
638		/* set up innards */
639		ss->states = &d->statesarea[i * d->wordsper];
640		ss->flags = 0;
641		ss->ins.ss = NULL;
642		ss->ins.co = WHITE;		/* give it some value */
643		ss->outs = &d->outsarea[i * d->ncolors];
644		ss->inchain = &d->incarea[i * d->ncolors];
645		for (i = 0; i < d->ncolors; i++) {
646			ss->outs[i] = NULL;
647			ss->inchain[i].ss = NULL;
648		}
649		return ss;
650	}
651
652	/* look for oldest, or old enough anyway */
653	if (cp - start > d->nssets*2/3)		/* oldest 33% are expendable */
654		ancient = cp - d->nssets*2/3;
655	else
656		ancient = start;
657	for (ss = d->search, end = &d->ssets[d->nssets]; ss < end; ss++)
658		if ((ss->lastseen == NULL || ss->lastseen < ancient) &&
659							!(ss->flags&LOCKED)) {
660			d->search = ss + 1;
661			FDEBUG(("replacing c%d\n", ss - d->ssets));
662			return ss;
663		}
664	for (ss = d->ssets, end = d->search; ss < end; ss++)
665		if ((ss->lastseen == NULL || ss->lastseen < ancient) &&
666							!(ss->flags&LOCKED)) {
667			d->search = ss + 1;
668			FDEBUG(("replacing c%d\n", ss - d->ssets));
669			return ss;
670		}
671
672	/* nobody's old enough?!? -- something's really wrong */
673	FDEBUG(("can't find victim to replace!\n"));
674	assert(NOTREACHED);
675	ERR(REG_ASSERT);
676	return d->ssets;
677}
678