Adding upstream version 14.5.upstream/14.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3824 insertions, 0 deletions

diff --git a/src/backend/regex/regc_nfa.c b/src/backend/regex/regc_nfa.c
new file mode 100644
index 0000000..0e93c74
--- /dev/null
+++ b/src/backend/regex/regc_nfa.c
@@ -0,0 +1,3824 @@
+/*
+ * NFA utilities.
+ * This file is #included by regcomp.c.
+ *
+ * Copyright (c) 1998, 1999 Henry Spencer.  All rights reserved.
+ *
+ * Development of this software was funded, in part, by Cray Research Inc.,
+ * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
+ * Corporation, none of whom are responsible for the results.  The author
+ * thanks all of them.
+ *
+ * Redistribution and use in source and binary forms -- with or without
+ * modification -- are permitted for any purpose, provided that
+ * redistributions in source form retain this entire copyright notice and
+ * indicate the origin and nature of any modifications.
+ *
+ * I'd appreciate being given credit for this package in the documentation
+ * of software which uses it, but that is not a requirement.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
+ * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * src/backend/regex/regc_nfa.c
+ *
+ *
+ * One or two things that technically ought to be in here
+ * are actually in color.c, thanks to some incestuous relationships in
+ * the color chains.
+ */
+
+#define NISERR()	VISERR(nfa->v)
+#define NERR(e)		VERR(nfa->v, (e))
+
+
+/*
+ * newnfa - set up an NFA
+ */
+static struct nfa *				/* the NFA, or NULL */
+newnfa(struct vars *v,
+	   struct colormap *cm,
+	   struct nfa *parent)		/* NULL if primary NFA */
+{
+	struct nfa *nfa;
+
+	nfa = (struct nfa *) MALLOC(sizeof(struct nfa));
+	if (nfa == NULL)
+	{
+		ERR(REG_ESPACE);
+		return NULL;
+	}
+
+	/* Make the NFA minimally valid, so freenfa() will behave sanely */
+	nfa->states = NULL;
+	nfa->slast = NULL;
+	nfa->freestates = NULL;
+	nfa->freearcs = NULL;
+	nfa->lastsb = NULL;
+	nfa->lastab = NULL;
+	nfa->lastsbused = 0;
+	nfa->lastabused = 0;
+	nfa->nstates = 0;
+	nfa->cm = cm;
+	nfa->v = v;
+	nfa->bos[0] = nfa->bos[1] = COLORLESS;
+	nfa->eos[0] = nfa->eos[1] = COLORLESS;
+	nfa->flags = 0;
+	nfa->minmatchall = nfa->maxmatchall = -1;
+	nfa->parent = parent;		/* Precedes newfstate so parent is valid. */
+
+	/* Create required infrastructure */
+	nfa->post = newfstate(nfa, '@');	/* number 0 */
+	nfa->pre = newfstate(nfa, '>'); /* number 1 */
+	nfa->init = newstate(nfa);	/* may become invalid later */
+	nfa->final = newstate(nfa);
+	if (ISERR())
+	{
+		freenfa(nfa);
+		return NULL;
+	}
+	rainbow(nfa, nfa->cm, PLAIN, COLORLESS, nfa->pre, nfa->init);
+	newarc(nfa, '^', 1, nfa->pre, nfa->init);
+	newarc(nfa, '^', 0, nfa->pre, nfa->init);
+	rainbow(nfa, nfa->cm, PLAIN, COLORLESS, nfa->final, nfa->post);
+	newarc(nfa, '$', 1, nfa->final, nfa->post);
+	newarc(nfa, '$', 0, nfa->final, nfa->post);
+
+	if (ISERR())
+	{
+		freenfa(nfa);
+		return NULL;
+	}
+	return nfa;
+}
+
+/*
+ * freenfa - free an entire NFA
+ */
+static void
+freenfa(struct nfa *nfa)
+{
+	struct statebatch *sb;
+	struct statebatch *sbnext;
+	struct arcbatch *ab;
+	struct arcbatch *abnext;
+
+	for (sb = nfa->lastsb; sb != NULL; sb = sbnext)
+	{
+		sbnext = sb->next;
+		nfa->v->spaceused -= STATEBATCHSIZE(sb->nstates);
+		FREE(sb);
+	}
+	nfa->lastsb = NULL;
+	for (ab = nfa->lastab; ab != NULL; ab = abnext)
+	{
+		abnext = ab->next;
+		nfa->v->spaceused -= ARCBATCHSIZE(ab->narcs);
+		FREE(ab);
+	}
+	nfa->lastab = NULL;
+
+	nfa->nstates = -1;
+	FREE(nfa);
+}
+
+/*
+ * newstate - allocate an NFA state, with zero flag value
+ */
+static struct state *			/* NULL on error */
+newstate(struct nfa *nfa)
+{
+	struct state *s;
+
+	/*
+	 * This is a handy place to check for operation cancel during regex
+	 * compilation, since no code path will go very long without making a new
+	 * state or arc.
+	 */
+	if (CANCEL_REQUESTED(nfa->v->re))
+	{
+		NERR(REG_CANCEL);
+		return NULL;
+	}
+
+	/* first, recycle anything that's on the freelist */
+	if (nfa->freestates != NULL)
+	{
+		s = nfa->freestates;
+		nfa->freestates = s->next;
+	}
+	/* otherwise, is there anything left in the last statebatch? */
+	else if (nfa->lastsb != NULL && nfa->lastsbused < nfa->lastsb->nstates)
+	{
+		s = &nfa->lastsb->s[nfa->lastsbused++];
+	}
+	/* otherwise, need to allocate a new statebatch */
+	else
+	{
+		struct statebatch *newSb;
+		size_t		nstates;
+
+		if (nfa->v->spaceused >= REG_MAX_COMPILE_SPACE)
+		{
+			NERR(REG_ETOOBIG);
+			return NULL;
+		}
+		nstates = (nfa->lastsb != NULL) ? nfa->lastsb->nstates * 2 : FIRSTSBSIZE;
+		if (nstates > MAXSBSIZE)
+			nstates = MAXSBSIZE;
+		newSb = (struct statebatch *) MALLOC(STATEBATCHSIZE(nstates));
+		if (newSb == NULL)
+		{
+			NERR(REG_ESPACE);
+			return NULL;
+		}
+		nfa->v->spaceused += STATEBATCHSIZE(nstates);
+		newSb->nstates = nstates;
+		newSb->next = nfa->lastsb;
+		nfa->lastsb = newSb;
+		nfa->lastsbused = 1;
+		s = &newSb->s[0];
+	}
+
+	assert(nfa->nstates >= 0);
+	s->no = nfa->nstates++;
+	s->flag = 0;
+	if (nfa->states == NULL)
+		nfa->states = s;
+	s->nins = 0;
+	s->ins = NULL;
+	s->nouts = 0;
+	s->outs = NULL;
+	s->tmp = NULL;
+	s->next = NULL;
+	if (nfa->slast != NULL)
+	{
+		assert(nfa->slast->next == NULL);
+		nfa->slast->next = s;
+	}
+	s->prev = nfa->slast;
+	nfa->slast = s;
+	return s;
+}
+
+/*
+ * newfstate - allocate an NFA state with a specified flag value
+ */
+static struct state *			/* NULL on error */
+newfstate(struct nfa *nfa, int flag)
+{
+	struct state *s;
+
+	s = newstate(nfa);
+	if (s != NULL)
+		s->flag = (char) flag;
+	return s;
+}
+
+/*
+ * dropstate - delete a state's inarcs and outarcs and free it
+ */
+static void
+dropstate(struct nfa *nfa,
+		  struct state *s)
+{
+	struct arc *a;
+
+	while ((a = s->ins) != NULL)
+		freearc(nfa, a);
+	while ((a = s->outs) != NULL)
+		freearc(nfa, a);
+	freestate(nfa, s);
+}
+
+/*
+ * freestate - free a state, which has no in-arcs or out-arcs
+ */
+static void
+freestate(struct nfa *nfa,
+		  struct state *s)
+{
+	assert(s != NULL);
+	assert(s->nins == 0 && s->nouts == 0);
+
+	s->no = FREESTATE;
+	s->flag = 0;
+	if (s->next != NULL)
+		s->next->prev = s->prev;
+	else
+	{
+		assert(s == nfa->slast);
+		nfa->slast = s->prev;
+	}
+	if (s->prev != NULL)
+		s->prev->next = s->next;
+	else
+	{
+		assert(s == nfa->states);
+		nfa->states = s->next;
+	}
+	s->prev = NULL;
+	s->next = nfa->freestates;	/* don't delete it, put it on the free list */
+	nfa->freestates = s;
+}
+
+/*
+ * newarc - set up a new arc within an NFA
+ *
+ * This function checks to make sure that no duplicate arcs are created.
+ * In general we never want duplicates.
+ *
+ * However: in principle, a RAINBOW arc is redundant with any plain arc
+ * (unless that arc is for a pseudocolor).  But we don't try to recognize
+ * that redundancy, either here or in allied operations such as moveins().
+ * The pseudocolor consideration makes that more costly than it seems worth.
+ */
+static void
+newarc(struct nfa *nfa,
+	   int t,
+	   color co,
+	   struct state *from,
+	   struct state *to)
+{
+	struct arc *a;
+
+	assert(from != NULL && to != NULL);
+
+	/*
+	 * This is a handy place to check for operation cancel during regex
+	 * compilation, since no code path will go very long without making a new
+	 * state or arc.
+	 */
+	if (CANCEL_REQUESTED(nfa->v->re))
+	{
+		NERR(REG_CANCEL);
+		return;
+	}
+
+	/* check for duplicate arc, using whichever chain is shorter */
+	if (from->nouts <= to->nins)
+	{
+		for (a = from->outs; a != NULL; a = a->outchain)
+			if (a->to == to && a->co == co && a->type == t)
+				return;
+	}
+	else
+	{
+		for (a = to->ins; a != NULL; a = a->inchain)
+			if (a->from == from && a->co == co && a->type == t)
+				return;
+	}
+
+	/* no dup, so create the arc */
+	createarc(nfa, t, co, from, to);
+}
+
+/*
+ * createarc - create a new arc within an NFA
+ *
+ * This function must *only* be used after verifying that there is no existing
+ * identical arc (same type/color/from/to).
+ */
+static void
+createarc(struct nfa *nfa,
+		  int t,
+		  color co,
+		  struct state *from,
+		  struct state *to)
+{
+	struct arc *a;
+
+	a = allocarc(nfa);
+	if (NISERR())
+		return;
+	assert(a != NULL);
+
+	a->type = t;
+	a->co = co;
+	a->to = to;
+	a->from = from;
+
+	/*
+	 * Put the new arc on the beginning, not the end, of the chains; it's
+	 * simpler here, and freearc() is the same cost either way.  See also the
+	 * logic in moveins() and its cohorts, as well as fixempties().
+	 */
+	a->inchain = to->ins;
+	a->inchainRev = NULL;
+	if (to->ins)
+		to->ins->inchainRev = a;
+	to->ins = a;
+	a->outchain = from->outs;
+	a->outchainRev = NULL;
+	if (from->outs)
+		from->outs->outchainRev = a;
+	from->outs = a;
+
+	from->nouts++;
+	to->nins++;
+
+	if (COLORED(a) && nfa->parent == NULL)
+		colorchain(nfa->cm, a);
+}
+
+/*
+ * allocarc - allocate a new arc within an NFA
+ */
+static struct arc *				/* NULL for failure */
+allocarc(struct nfa *nfa)
+{
+	struct arc *a;
+
+	/* first, recycle anything that's on the freelist */
+	if (nfa->freearcs != NULL)
+	{
+		a = nfa->freearcs;
+		nfa->freearcs = a->freechain;
+	}
+	/* otherwise, is there anything left in the last arcbatch? */
+	else if (nfa->lastab != NULL && nfa->lastabused < nfa->lastab->narcs)
+	{
+		a = &nfa->lastab->a[nfa->lastabused++];
+	}
+	/* otherwise, need to allocate a new arcbatch */
+	else
+	{
+		struct arcbatch *newAb;
+		size_t		narcs;
+
+		if (nfa->v->spaceused >= REG_MAX_COMPILE_SPACE)
+		{
+			NERR(REG_ETOOBIG);
+			return NULL;
+		}
+		narcs = (nfa->lastab != NULL) ? nfa->lastab->narcs * 2 : FIRSTABSIZE;
+		if (narcs > MAXABSIZE)
+			narcs = MAXABSIZE;
+		newAb = (struct arcbatch *) MALLOC(ARCBATCHSIZE(narcs));
+		if (newAb == NULL)
+		{
+			NERR(REG_ESPACE);
+			return NULL;
+		}
+		nfa->v->spaceused += ARCBATCHSIZE(narcs);
+		newAb->narcs = narcs;
+		newAb->next = nfa->lastab;
+		nfa->lastab = newAb;
+		nfa->lastabused = 1;
+		a = &newAb->a[0];
+	}
+
+	return a;
+}
+
+/*
+ * freearc - free an arc
+ */
+static void
+freearc(struct nfa *nfa,
+		struct arc *victim)
+{
+	struct state *from = victim->from;
+	struct state *to = victim->to;
+	struct arc *predecessor;
+
+	assert(victim->type != 0);
+
+	/* take it off color chain if necessary */
+	if (COLORED(victim) && nfa->parent == NULL)
+		uncolorchain(nfa->cm, victim);
+
+	/* take it off source's out-chain */
+	assert(from != NULL);
+	predecessor = victim->outchainRev;
+	if (predecessor == NULL)
+	{
+		assert(from->outs == victim);
+		from->outs = victim->outchain;
+	}
+	else
+	{
+		assert(predecessor->outchain == victim);
+		predecessor->outchain = victim->outchain;
+	}
+	if (victim->outchain != NULL)
+	{
+		assert(victim->outchain->outchainRev == victim);
+		victim->outchain->outchainRev = predecessor;
+	}
+	from->nouts--;
+
+	/* take it off target's in-chain */
+	assert(to != NULL);
+	predecessor = victim->inchainRev;
+	if (predecessor == NULL)
+	{
+		assert(to->ins == victim);
+		to->ins = victim->inchain;
+	}
+	else
+	{
+		assert(predecessor->inchain == victim);
+		predecessor->inchain = victim->inchain;
+	}
+	if (victim->inchain != NULL)
+	{
+		assert(victim->inchain->inchainRev == victim);
+		victim->inchain->inchainRev = predecessor;
+	}
+	to->nins--;
+
+	/* clean up and place on NFA's free list */
+	victim->type = 0;
+	victim->from = NULL;		/* precautions... */
+	victim->to = NULL;
+	victim->inchain = NULL;
+	victim->inchainRev = NULL;
+	victim->outchain = NULL;
+	victim->outchainRev = NULL;
+	victim->freechain = nfa->freearcs;
+	nfa->freearcs = victim;
+}
+
+/*
+ * changearcsource - flip an arc to have a different from state
+ *
+ * Caller must have verified that there is no pre-existing duplicate arc.
+ */
+static void
+changearcsource(struct arc *a, struct state *newfrom)
+{
+	struct state *oldfrom = a->from;
+	struct arc *predecessor;
+
+	assert(oldfrom != newfrom);
+
+	/* take it off old source's out-chain */
+	assert(oldfrom != NULL);
+	predecessor = a->outchainRev;
+	if (predecessor == NULL)
+	{
+		assert(oldfrom->outs == a);
+		oldfrom->outs = a->outchain;
+	}
+	else
+	{
+		assert(predecessor->outchain == a);
+		predecessor->outchain = a->outchain;
+	}
+	if (a->outchain != NULL)
+	{
+		assert(a->outchain->outchainRev == a);
+		a->outchain->outchainRev = predecessor;
+	}
+	oldfrom->nouts--;
+
+	a->from = newfrom;
+
+	/* prepend it to new source's out-chain */
+	a->outchain = newfrom->outs;
+	a->outchainRev = NULL;
+	if (newfrom->outs)
+		newfrom->outs->outchainRev = a;
+	newfrom->outs = a;
+	newfrom->nouts++;
+}
+
+/*
+ * changearctarget - flip an arc to have a different to state
+ *
+ * Caller must have verified that there is no pre-existing duplicate arc.
+ */
+static void
+changearctarget(struct arc *a, struct state *newto)
+{
+	struct state *oldto = a->to;
+	struct arc *predecessor;
+
+	assert(oldto != newto);
+
+	/* take it off old target's in-chain */
+	assert(oldto != NULL);
+	predecessor = a->inchainRev;
+	if (predecessor == NULL)
+	{
+		assert(oldto->ins == a);
+		oldto->ins = a->inchain;
+	}
+	else
+	{
+		assert(predecessor->inchain == a);
+		predecessor->inchain = a->inchain;
+	}
+	if (a->inchain != NULL)
+	{
+		assert(a->inchain->inchainRev == a);
+		a->inchain->inchainRev = predecessor;
+	}
+	oldto->nins--;
+
+	a->to = newto;
+
+	/* prepend it to new target's in-chain */
+	a->inchain = newto->ins;
+	a->inchainRev = NULL;
+	if (newto->ins)
+		newto->ins->inchainRev = a;
+	newto->ins = a;
+	newto->nins++;
+}
+
+/*
+ * hasnonemptyout - Does state have a non-EMPTY out arc?
+ */
+static int
+hasnonemptyout(struct state *s)
+{
+	struct arc *a;
+
+	for (a = s->outs; a != NULL; a = a->outchain)
+	{
+		if (a->type != EMPTY)
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * findarc - find arc, if any, from given source with given type and color
+ * If there is more than one such arc, the result is random.
+ */
+static struct arc *
+findarc(struct state *s,
+		int type,
+		color co)
+{
+	struct arc *a;
+
+	for (a = s->outs; a != NULL; a = a->outchain)
+		if (a->type == type && a->co == co)
+			return a;
+	return NULL;
+}
+
+/*
+ * cparc - allocate a new arc within an NFA, copying details from old one
+ */
+static void
+cparc(struct nfa *nfa,
+	  struct arc *oa,
+	  struct state *from,
+	  struct state *to)
+{
+	newarc(nfa, oa->type, oa->co, from, to);
+}
+
+/*
+ * sortins - sort the in arcs of a state by from/color/type
+ */
+static void
+sortins(struct nfa *nfa,
+		struct state *s)
+{
+	struct arc **sortarray;
+	struct arc *a;
+	int			n = s->nins;
+	int			i;
+
+	if (n <= 1)
+		return;					/* nothing to do */
+	/* make an array of arc pointers ... */
+	sortarray = (struct arc **) MALLOC(n * sizeof(struct arc *));
+	if (sortarray == NULL)
+	{
+		NERR(REG_ESPACE);
+		return;
+	}
+	i = 0;
+	for (a = s->ins; a != NULL; a = a->inchain)
+		sortarray[i++] = a;
+	assert(i == n);
+	/* ... sort the array */
+	qsort(sortarray, n, sizeof(struct arc *), sortins_cmp);
+	/* ... and rebuild arc list in order */
+	/* it seems worth special-casing first and last items to simplify loop */
+	a = sortarray[0];
+	s->ins = a;
+	a->inchain = sortarray[1];
+	a->inchainRev = NULL;
+	for (i = 1; i < n - 1; i++)
+	{
+		a = sortarray[i];
+		a->inchain = sortarray[i + 1];
+		a->inchainRev = sortarray[i - 1];
+	}
+	a = sortarray[i];
+	a->inchain = NULL;
+	a->inchainRev = sortarray[i - 1];
+	FREE(sortarray);
+}
+
+static int
+sortins_cmp(const void *a, const void *b)
+{
+	const struct arc *aa = *((const struct arc *const *) a);
+	const struct arc *bb = *((const struct arc *const *) b);
+
+	/* we check the fields in the order they are most likely to be different */
+	if (aa->from->no < bb->from->no)
+		return -1;
+	if (aa->from->no > bb->from->no)
+		return 1;
+	if (aa->co < bb->co)
+		return -1;
+	if (aa->co > bb->co)
+		return 1;
+	if (aa->type < bb->type)
+		return -1;
+	if (aa->type > bb->type)
+		return 1;
+	return 0;
+}
+
+/*
+ * sortouts - sort the out arcs of a state by to/color/type
+ */
+static void
+sortouts(struct nfa *nfa,
+		 struct state *s)
+{
+	struct arc **sortarray;
+	struct arc *a;
+	int			n = s->nouts;
+	int			i;
+
+	if (n <= 1)
+		return;					/* nothing to do */
+	/* make an array of arc pointers ... */
+	sortarray = (struct arc **) MALLOC(n * sizeof(struct arc *));
+	if (sortarray == NULL)
+	{
+		NERR(REG_ESPACE);
+		return;
+	}
+	i = 0;
+	for (a = s->outs; a != NULL; a = a->outchain)
+		sortarray[i++] = a;
+	assert(i == n);
+	/* ... sort the array */
+	qsort(sortarray, n, sizeof(struct arc *), sortouts_cmp);
+	/* ... and rebuild arc list in order */
+	/* it seems worth special-casing first and last items to simplify loop */
+	a = sortarray[0];
+	s->outs = a;
+	a->outchain = sortarray[1];
+	a->outchainRev = NULL;
+	for (i = 1; i < n - 1; i++)
+	{
+		a = sortarray[i];
+		a->outchain = sortarray[i + 1];
+		a->outchainRev = sortarray[i - 1];
+	}
+	a = sortarray[i];
+	a->outchain = NULL;
+	a->outchainRev = sortarray[i - 1];
+	FREE(sortarray);
+}
+
+static int
+sortouts_cmp(const void *a, const void *b)
+{
+	const struct arc *aa = *((const struct arc *const *) a);
+	const struct arc *bb = *((const struct arc *const *) b);
+
+	/* we check the fields in the order they are most likely to be different */
+	if (aa->to->no < bb->to->no)
+		return -1;
+	if (aa->to->no > bb->to->no)
+		return 1;
+	if (aa->co < bb->co)
+		return -1;
+	if (aa->co > bb->co)
+		return 1;
+	if (aa->type < bb->type)
+		return -1;
+	if (aa->type > bb->type)
+		return 1;
+	return 0;
+}
+
+/*
+ * Common decision logic about whether to use arc-by-arc operations or
+ * sort/merge.  If there's just a few source arcs we cannot recoup the
+ * cost of sorting the destination arc list, no matter how large it is.
+ * Otherwise, limit the number of arc-by-arc comparisons to about 1000
+ * (a somewhat arbitrary choice, but the breakeven point would probably
+ * be machine dependent anyway).
+ */
+#define BULK_ARC_OP_USE_SORT(nsrcarcs, ndestarcs) \
+	((nsrcarcs) < 4 ? 0 : ((nsrcarcs) > 32 || (ndestarcs) > 32))
+
+/*
+ * moveins - move all in arcs of a state to another state
+ *
+ * You might think this could be done better by just updating the
+ * existing arcs, and you would be right if it weren't for the need
+ * for duplicate suppression, which makes it easier to just make new
+ * ones to exploit the suppression built into newarc.
+ *
+ * However, if we have a whole lot of arcs to deal with, retail duplicate
+ * checks become too slow.  In that case we proceed by sorting and merging
+ * the arc lists, and then we can indeed just update the arcs in-place.
+ */
+static void
+moveins(struct nfa *nfa,
+		struct state *oldState,
+		struct state *newState)
+{
+	assert(oldState != newState);
+
+	if (!BULK_ARC_OP_USE_SORT(oldState->nins, newState->nins))
+	{
+		/* With not too many arcs, just do them one at a time */
+		struct arc *a;
+
+		while ((a = oldState->ins) != NULL)
+		{
+			cparc(nfa, a, a->from, newState);
+			freearc(nfa, a);
+		}
+	}
+	else
+	{
+		/*
+		 * With many arcs, use a sort-merge approach.  Note changearctarget()
+		 * will put the arc onto the front of newState's chain, so it does not
+		 * break our walk through the sorted part of the chain.
+		 */
+		struct arc *oa;
+		struct arc *na;
+
+		/*
+		 * Because we bypass newarc() in this code path, we'd better include a
+		 * cancel check.
+		 */
+		if (CANCEL_REQUESTED(nfa->v->re))
+		{
+			NERR(REG_CANCEL);
+			return;
+		}
+
+		sortins(nfa, oldState);
+		sortins(nfa, newState);
+		if (NISERR())
+			return;				/* might have failed to sort */
+		oa = oldState->ins;
+		na = newState->ins;
+		while (oa != NULL && na != NULL)
+		{
+			struct arc *a = oa;
+
+			switch (sortins_cmp(&oa, &na))
+			{
+				case -1:
+					/* newState does not have anything matching oa */
+					oa = oa->inchain;
+
+					/*
+					 * Rather than doing createarc+freearc, we can just unlink
+					 * and relink the existing arc struct.
+					 */
+					changearctarget(a, newState);
+					break;
+				case 0:
+					/* match, advance in both lists */
+					oa = oa->inchain;
+					na = na->inchain;
+					/* ... and drop duplicate arc from oldState */
+					freearc(nfa, a);
+					break;
+				case +1:
+					/* advance only na; oa might have a match later */
+					na = na->inchain;
+					break;
+				default:
+					assert(NOTREACHED);
+			}
+		}
+		while (oa != NULL)
+		{
+			/* newState does not have anything matching oa */
+			struct arc *a = oa;
+
+			oa = oa->inchain;
+			changearctarget(a, newState);
+		}
+	}
+
+	assert(oldState->nins == 0);
+	assert(oldState->ins == NULL);
+}
+
+/*
+ * copyins - copy in arcs of a state to another state
+ */
+static void
+copyins(struct nfa *nfa,
+		struct state *oldState,
+		struct state *newState)
+{
+	assert(oldState != newState);
+
+	if (!BULK_ARC_OP_USE_SORT(oldState->nins, newState->nins))
+	{
+		/* With not too many arcs, just do them one at a time */
+		struct arc *a;
+
+		for (a = oldState->ins; a != NULL; a = a->inchain)
+			cparc(nfa, a, a->from, newState);
+	}
+	else
+	{
+		/*
+		 * With many arcs, use a sort-merge approach.  Note that createarc()
+		 * will put new arcs onto the front of newState's chain, so it does
+		 * not break our walk through the sorted part of the chain.
+		 */
+		struct arc *oa;
+		struct arc *na;
+
+		/*
+		 * Because we bypass newarc() in this code path, we'd better include a
+		 * cancel check.
+		 */
+		if (CANCEL_REQUESTED(nfa->v->re))
+		{
+			NERR(REG_CANCEL);
+			return;
+		}
+
+		sortins(nfa, oldState);
+		sortins(nfa, newState);
+		if (NISERR())
+			return;				/* might have failed to sort */
+		oa = oldState->ins;
+		na = newState->ins;
+		while (oa != NULL && na != NULL)
+		{
+			struct arc *a = oa;
+
+			switch (sortins_cmp(&oa, &na))
+			{
+				case -1:
+					/* newState does not have anything matching oa */
+					oa = oa->inchain;
+					createarc(nfa, a->type, a->co, a->from, newState);
+					break;
+				case 0:
+					/* match, advance in both lists */
+					oa = oa->inchain;
+					na = na->inchain;
+					break;
+				case +1:
+					/* advance only na; oa might have a match later */
+					na = na->inchain;
+					break;
+				default:
+					assert(NOTREACHED);
+			}
+		}
+		while (oa != NULL)
+		{
+			/* newState does not have anything matching oa */
+			struct arc *a = oa;
+
+			oa = oa->inchain;
+			createarc(nfa, a->type, a->co, a->from, newState);
+		}
+	}
+}
+
+/*
+ * mergeins - merge a list of inarcs into a state
+ *
+ * This is much like copyins, but the source arcs are listed in an array,
+ * and are not guaranteed unique.  It's okay to clobber the array contents.
+ */
+static void
+mergeins(struct nfa *nfa,
+		 struct state *s,
+		 struct arc **arcarray,
+		 int arccount)
+{
+	struct arc *na;
+	int			i;
+	int			j;
+
+	if (arccount <= 0)
+		return;
+
+	/*
+	 * Because we bypass newarc() in this code path, we'd better include a
+	 * cancel check.
+	 */
+	if (CANCEL_REQUESTED(nfa->v->re))
+	{
+		NERR(REG_CANCEL);
+		return;
+	}
+
+	/* Sort existing inarcs as well as proposed new ones */
+	sortins(nfa, s);
+	if (NISERR())
+		return;					/* might have failed to sort */
+
+	qsort(arcarray, arccount, sizeof(struct arc *), sortins_cmp);
+
+	/*
+	 * arcarray very likely includes dups, so we must eliminate them.  (This
+	 * could be folded into the next loop, but it's not worth the trouble.)
+	 */
+	j = 0;
+	for (i = 1; i < arccount; i++)
+	{
+		switch (sortins_cmp(&arcarray[j], &arcarray[i]))
+		{
+			case -1:
+				/* non-dup */
+				arcarray[++j] = arcarray[i];
+				break;
+			case 0:
+				/* dup */
+				break;
+			default:
+				/* trouble */
+				assert(NOTREACHED);
+		}
+	}
+	arccount = j + 1;
+
+	/*
+	 * Now merge into s' inchain.  Note that createarc() will put new arcs
+	 * onto the front of s's chain, so it does not break our walk through the
+	 * sorted part of the chain.
+	 */
+	i = 0;
+	na = s->ins;
+	while (i < arccount && na != NULL)
+	{
+		struct arc *a = arcarray[i];
+
+		switch (sortins_cmp(&a, &na))
+		{
+			case -1:
+				/* s does not have anything matching a */
+				createarc(nfa, a->type, a->co, a->from, s);
+				i++;
+				break;
+			case 0:
+				/* match, advance in both lists */
+				i++;
+				na = na->inchain;
+				break;
+			case +1:
+				/* advance only na; array might have a match later */
+				na = na->inchain;
+				break;
+			default:
+				assert(NOTREACHED);
+		}
+	}
+	while (i < arccount)
+	{
+		/* s does not have anything matching a */
+		struct arc *a = arcarray[i];
+
+		createarc(nfa, a->type, a->co, a->from, s);
+		i++;
+	}
+}
+
+/*
+ * moveouts - move all out arcs of a state to another state
+ *
+ * See comments for moveins()
+ */
+static void
+moveouts(struct nfa *nfa,
+		 struct state *oldState,
+		 struct state *newState)
+{
+	assert(oldState != newState);
+
+	if (!BULK_ARC_OP_USE_SORT(oldState->nouts, newState->nouts))
+	{
+		/* With not too many arcs, just do them one at a time */
+		struct arc *a;
+
+		while ((a = oldState->outs) != NULL)
+		{
+			cparc(nfa, a, newState, a->to);
+			freearc(nfa, a);
+		}
+	}
+	else
+	{
+		/*
+		 * With many arcs, use a sort-merge approach.  Note changearcsource()
+		 * will put the arc onto the front of newState's chain, so it does not
+		 * break our walk through the sorted part of the chain.
+		 */
+		struct arc *oa;
+		struct arc *na;
+
+		/*
+		 * Because we bypass newarc() in this code path, we'd better include a
+		 * cancel check.
+		 */
+		if (CANCEL_REQUESTED(nfa->v->re))
+		{
+			NERR(REG_CANCEL);
+			return;
+		}
+
+		sortouts(nfa, oldState);
+		sortouts(nfa, newState);
+		if (NISERR())
+			return;				/* might have failed to sort */
+		oa = oldState->outs;
+		na = newState->outs;
+		while (oa != NULL && na != NULL)
+		{
+			struct arc *a = oa;
+
+			switch (sortouts_cmp(&oa, &na))
+			{
+				case -1:
+					/* newState does not have anything matching oa */
+					oa = oa->outchain;
+
+					/*
+					 * Rather than doing createarc+freearc, we can just unlink
+					 * and relink the existing arc struct.
+					 */
+					changearcsource(a, newState);
+					break;
+				case 0:
+					/* match, advance in both lists */
+					oa = oa->outchain;
+					na = na->outchain;
+					/* ... and drop duplicate arc from oldState */
+					freearc(nfa, a);
+					break;
+				case +1:
+					/* advance only na; oa might have a match later */
+					na = na->outchain;
+					break;
+				default:
+					assert(NOTREACHED);
+			}
+		}
+		while (oa != NULL)
+		{
+			/* newState does not have anything matching oa */
+			struct arc *a = oa;
+
+			oa = oa->outchain;
+			changearcsource(a, newState);
+		}
+	}
+
+	assert(oldState->nouts == 0);
+	assert(oldState->outs == NULL);
+}
+
+/*
+ * copyouts - copy out arcs of a state to another state
+ */
+static void
+copyouts(struct nfa *nfa,
+		 struct state *oldState,
+		 struct state *newState)
+{
+	assert(oldState != newState);
+
+	if (!BULK_ARC_OP_USE_SORT(oldState->nouts, newState->nouts))
+	{
+		/* With not too many arcs, just do them one at a time */
+		struct arc *a;
+
+		for (a = oldState->outs; a != NULL; a = a->outchain)
+			cparc(nfa, a, newState, a->to);
+	}
+	else
+	{
+		/*
+		 * With many arcs, use a sort-merge approach.  Note that createarc()
+		 * will put new arcs onto the front of newState's chain, so it does
+		 * not break our walk through the sorted part of the chain.
+		 */
+		struct arc *oa;
+		struct arc *na;
+
+		/*
+		 * Because we bypass newarc() in this code path, we'd better include a
+		 * cancel check.
+		 */
+		if (CANCEL_REQUESTED(nfa->v->re))
+		{
+			NERR(REG_CANCEL);
+			return;
+		}
+
+		sortouts(nfa, oldState);
+		sortouts(nfa, newState);
+		if (NISERR())
+			return;				/* might have failed to sort */
+		oa = oldState->outs;
+		na = newState->outs;
+		while (oa != NULL && na != NULL)
+		{
+			struct arc *a = oa;
+
+			switch (sortouts_cmp(&oa, &na))
+			{
+				case -1:
+					/* newState does not have anything matching oa */
+					oa = oa->outchain;
+					createarc(nfa, a->type, a->co, newState, a->to);
+					break;
+				case 0:
+					/* match, advance in both lists */
+					oa = oa->outchain;
+					na = na->outchain;
+					break;
+				case +1:
+					/* advance only na; oa might have a match later */
+					na = na->outchain;
+					break;
+				default:
+					assert(NOTREACHED);
+			}
+		}
+		while (oa != NULL)
+		{
+			/* newState does not have anything matching oa */
+			struct arc *a = oa;
+
+			oa = oa->outchain;
+			createarc(nfa, a->type, a->co, newState, a->to);
+		}
+	}
+}
+
+/*
+ * cloneouts - copy out arcs of a state to another state pair, modifying type
+ *
+ * This is only used to convert PLAIN arcs to AHEAD/BEHIND arcs, which share
+ * the same interpretation of "co".  It wouldn't be sensible with LACONs.
+ */
+static void
+cloneouts(struct nfa *nfa,
+		  struct state *old,
+		  struct state *from,
+		  struct state *to,
+		  int type)
+{
+	struct arc *a;
+
+	assert(old != from);
+	assert(type == AHEAD || type == BEHIND);
+
+	for (a = old->outs; a != NULL; a = a->outchain)
+	{
+		assert(a->type == PLAIN);
+		newarc(nfa, type, a->co, from, to);
+	}
+}
+
+/*
+ * delsub - delete a sub-NFA, updating subre pointers if necessary
+ *
+ * This uses a recursive traversal of the sub-NFA, marking already-seen
+ * states using their tmp pointer.
+ */
+static void
+delsub(struct nfa *nfa,
+	   struct state *lp,		/* the sub-NFA goes from here... */
+	   struct state *rp)		/* ...to here, *not* inclusive */
+{
+	assert(lp != rp);
+
+	rp->tmp = rp;				/* mark end */
+
+	deltraverse(nfa, lp, lp);
+	if (NISERR())
+		return;					/* asserts might not hold after failure */
+	assert(lp->nouts == 0 && rp->nins == 0);	/* did the job */
+	assert(lp->no != FREESTATE && rp->no != FREESTATE); /* no more */
+
+	rp->tmp = NULL;				/* unmark end */
+	lp->tmp = NULL;				/* and begin, marked by deltraverse */
+}
+
+/*
+ * deltraverse - the recursive heart of delsub
+ * This routine's basic job is to destroy all out-arcs of the state.
+ */
+static void
+deltraverse(struct nfa *nfa,
+			struct state *leftend,
+			struct state *s)
+{
+	struct arc *a;
+	struct state *to;
+
+	/* Since this is recursive, it could be driven to stack overflow */
+	if (STACK_TOO_DEEP(nfa->v->re))
+	{
+		NERR(REG_ETOOBIG);
+		return;
+	}
+
+	if (s->nouts == 0)
+		return;					/* nothing to do */
+	if (s->tmp != NULL)
+		return;					/* already in progress */
+
+	s->tmp = s;					/* mark as in progress */
+
+	while ((a = s->outs) != NULL)
+	{
+		to = a->to;
+		deltraverse(nfa, leftend, to);
+		if (NISERR())
+			return;				/* asserts might not hold after failure */
+		assert(to->nouts == 0 || to->tmp != NULL);
+		freearc(nfa, a);
+		if (to->nins == 0 && to->tmp == NULL)
+		{
+			assert(to->nouts == 0);
+			freestate(nfa, to);
+		}
+	}
+
+	assert(s->no != FREESTATE); /* we're still here */
+	assert(s == leftend || s->nins != 0);	/* and still reachable */
+	assert(s->nouts == 0);		/* but have no outarcs */
+
+	s->tmp = NULL;				/* we're done here */
+}
+
+/*
+ * dupnfa - duplicate sub-NFA
+ *
+ * Another recursive traversal, this time using tmp to point to duplicates
+ * as well as mark already-seen states.  (You knew there was a reason why
+ * it's a state pointer, didn't you? :-))
+ */
+static void
+dupnfa(struct nfa *nfa,
+	   struct state *start,		/* duplicate of subNFA starting here */
+	   struct state *stop,		/* and stopping here */
+	   struct state *from,		/* stringing duplicate from here */
+	   struct state *to)		/* to here */
+{
+	if (start == stop)
+	{
+		newarc(nfa, EMPTY, 0, from, to);
+		return;
+	}
+
+	stop->tmp = to;
+	duptraverse(nfa, start, from);
+	/* done, except for clearing out the tmp pointers */
+
+	stop->tmp = NULL;
+	cleartraverse(nfa, start);
+}
+
+/*
+ * duptraverse - recursive heart of dupnfa
+ */
+static void
+duptraverse(struct nfa *nfa,
+			struct state *s,
+			struct state *stmp) /* s's duplicate, or NULL */
+{
+	struct arc *a;
+
+	/* Since this is recursive, it could be driven to stack overflow */
+	if (STACK_TOO_DEEP(nfa->v->re))
+	{
+		NERR(REG_ETOOBIG);
+		return;
+	}
+
+	if (s->tmp != NULL)
+		return;					/* already done */
+
+	s->tmp = (stmp == NULL) ? newstate(nfa) : stmp;
+	if (s->tmp == NULL)
+	{
+		assert(NISERR());
+		return;
+	}
+
+	for (a = s->outs; a != NULL && !NISERR(); a = a->outchain)
+	{
+		duptraverse(nfa, a->to, (struct state *) NULL);
+		if (NISERR())
+			break;
+		assert(a->to->tmp != NULL);
+		cparc(nfa, a, s->tmp, a->to->tmp);
+	}
+}
+
+/*
+ * removeconstraints - remove any constraints in an NFA
+ *
+ * Constraint arcs are replaced by empty arcs, essentially treating all
+ * constraints as automatically satisfied.
+ */
+static void
+removeconstraints(struct nfa *nfa,
+				  struct state *start,	/* process subNFA starting here */
+				  struct state *stop)	/* and stopping here */
+{
+	if (start == stop)
+		return;
+
+	stop->tmp = stop;
+	removetraverse(nfa, start);
+	/* done, except for clearing out the tmp pointers */
+
+	stop->tmp = NULL;
+	cleartraverse(nfa, start);
+}
+
+/*
+ * removetraverse - recursive heart of removeconstraints
+ */
+static void
+removetraverse(struct nfa *nfa,
+			   struct state *s)
+{
+	struct arc *a;
+	struct arc *oa;
+
+	/* Since this is recursive, it could be driven to stack overflow */
+	if (STACK_TOO_DEEP(nfa->v->re))
+	{
+		NERR(REG_ETOOBIG);
+		return;
+	}
+
+	if (s->tmp != NULL)
+		return;					/* already done */
+
+	s->tmp = s;
+	for (a = s->outs; a != NULL && !NISERR(); a = oa)
+	{
+		removetraverse(nfa, a->to);
+		if (NISERR())
+			break;
+		oa = a->outchain;
+		switch (a->type)
+		{
+			case PLAIN:
+			case EMPTY:
+				/* nothing to do */
+				break;
+			case AHEAD:
+			case BEHIND:
+			case '^':
+			case '$':
+			case LACON:
+				/* replace it */
+				newarc(nfa, EMPTY, 0, s, a->to);
+				freearc(nfa, a);
+				break;
+			default:
+				NERR(REG_ASSERT);
+				break;
+		}
+	}
+}
+
+/*
+ * cleartraverse - recursive cleanup for algorithms that leave tmp ptrs set
+ */
+static void
+cleartraverse(struct nfa *nfa,
+			  struct state *s)
+{
+	struct arc *a;
+
+	/* Since this is recursive, it could be driven to stack overflow */
+	if (STACK_TOO_DEEP(nfa->v->re))
+	{
+		NERR(REG_ETOOBIG);
+		return;
+	}
+
+	if (s->tmp == NULL)
+		return;
+	s->tmp = NULL;
+
+	for (a = s->outs; a != NULL; a = a->outchain)
+		cleartraverse(nfa, a->to);
+}
+
+/*
+ * single_color_transition - does getting from s1 to s2 cross one PLAIN arc?
+ *
+ * If traversing from s1 to s2 requires a single PLAIN match (possibly of any
+ * of a set of colors), return a state whose outarc list contains only PLAIN
+ * arcs of those color(s).  Otherwise return NULL.
+ *
+ * This is used before optimizing the NFA, so there may be EMPTY arcs, which
+ * we should ignore; the possibility of an EMPTY is why the result state could
+ * be different from s1.
+ *
+ * It's worth troubling to handle multiple parallel PLAIN arcs here because a
+ * bracket construct such as [abc] might yield either one or several parallel
+ * PLAIN arcs depending on earlier atoms in the expression.  We'd rather that
+ * that implementation detail not create user-visible performance differences.
+ */
+static struct state *
+single_color_transition(struct state *s1, struct state *s2)
+{
+	struct arc *a;
+
+	/* Ignore leading EMPTY arc, if any */
+	if (s1->nouts == 1 && s1->outs->type == EMPTY)
+		s1 = s1->outs->to;
+	/* Likewise for any trailing EMPTY arc */
+	if (s2->nins == 1 && s2->ins->type == EMPTY)
+		s2 = s2->ins->from;
+	/* Perhaps we could have a single-state loop in between, if so reject */
+	if (s1 == s2)
+		return NULL;
+	/* s1 must have at least one outarc... */
+	if (s1->outs == NULL)
+		return NULL;
+	/* ... and they must all be PLAIN arcs to s2 */
+	for (a = s1->outs; a != NULL; a = a->outchain)
+	{
+		if (a->type != PLAIN || a->to != s2)
+			return NULL;
+	}
+	/* OK, return s1 as the possessor of the relevant outarcs */
+	return s1;
+}
+
+/*
+ * specialcolors - fill in special colors for an NFA
+ */
+static void
+specialcolors(struct nfa *nfa)
+{
+	/* false colors for BOS, BOL, EOS, EOL */
+	if (nfa->parent == NULL)
+	{
+		nfa->bos[0] = pseudocolor(nfa->cm);
+		nfa->bos[1] = pseudocolor(nfa->cm);
+		nfa->eos[0] = pseudocolor(nfa->cm);
+		nfa->eos[1] = pseudocolor(nfa->cm);
+	}
+	else
+	{
+		assert(nfa->parent->bos[0] != COLORLESS);
+		nfa->bos[0] = nfa->parent->bos[0];
+		assert(nfa->parent->bos[1] != COLORLESS);
+		nfa->bos[1] = nfa->parent->bos[1];
+		assert(nfa->parent->eos[0] != COLORLESS);
+		nfa->eos[0] = nfa->parent->eos[0];
+		assert(nfa->parent->eos[1] != COLORLESS);
+		nfa->eos[1] = nfa->parent->eos[1];
+	}
+}
+
+/*
+ * optimize - optimize an NFA
+ *
+ * The main goal of this function is not so much "optimization" (though it
+ * does try to get rid of useless NFA states) as reducing the NFA to a form
+ * the regex executor can handle.  The executor, and indeed the cNFA format
+ * that is its input, can only handle PLAIN and LACON arcs.  The output of
+ * the regex parser also includes EMPTY (do-nothing) arcs, as well as
+ * ^, $, AHEAD, and BEHIND constraint arcs, which we must get rid of here.
+ * We first get rid of EMPTY arcs and then deal with the constraint arcs.
+ * The hardest part of either job is to get rid of circular loops of the
+ * target arc type.  We would have to do that in any case, though, as such a
+ * loop would otherwise allow the executor to cycle through the loop endlessly
+ * without making any progress in the input string.
+ */
+static long						/* re_info bits */
+optimize(struct nfa *nfa,
+		 FILE *f)				/* for debug output; NULL none */
+{
+#ifdef REG_DEBUG
+	int			verbose = (f != NULL) ? 1 : 0;
+
+	if (verbose)
+		fprintf(f, "\ninitial cleanup:\n");
+#endif
+	cleanup(nfa);				/* may simplify situation */
+#ifdef REG_DEBUG
+	if (verbose)
+		dumpnfa(nfa, f);
+	if (verbose)
+		fprintf(f, "\nempties:\n");
+#endif
+	fixempties(nfa, f);			/* get rid of EMPTY arcs */
+#ifdef REG_DEBUG
+	if (verbose)
+		fprintf(f, "\nconstraints:\n");
+#endif
+	fixconstraintloops(nfa, f); /* get rid of constraint loops */
+	pullback(nfa, f);			/* pull back constraints backward */
+	pushfwd(nfa, f);			/* push fwd constraints forward */
+#ifdef REG_DEBUG
+	if (verbose)
+		fprintf(f, "\nfinal cleanup:\n");
+#endif
+	cleanup(nfa);				/* final tidying */
+#ifdef REG_DEBUG
+	if (verbose)
+		dumpnfa(nfa, f);
+#endif
+	return analyze(nfa);		/* and analysis */
+}
+
+/*
+ * pullback - pull back constraints backward to eliminate them
+ */
+static void
+pullback(struct nfa *nfa,
+		 FILE *f)				/* for debug output; NULL none */
+{
+	struct state *s;
+	struct state *nexts;
+	struct arc *a;
+	struct arc *nexta;
+	struct state *intermediates;
+	int			progress;
+
+	/* find and pull until there are no more */
+	do
+	{
+		progress = 0;
+		for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
+		{
+			nexts = s->next;
+			intermediates = NULL;
+			for (a = s->outs; a != NULL && !NISERR(); a = nexta)
+			{
+				nexta = a->outchain;
+				if (a->type == '^' || a->type == BEHIND)
+					if (pull(nfa, a, &intermediates))
+						progress = 1;
+			}
+			/* clear tmp fields of intermediate states created here */
+			while (intermediates != NULL)
+			{
+				struct state *ns = intermediates->tmp;
+
+				intermediates->tmp = NULL;
+				intermediates = ns;
+			}
+			/* if s is now useless, get rid of it */
+			if ((s->nins == 0 || s->nouts == 0) && !s->flag)
+				dropstate(nfa, s);
+		}
+		if (progress && f != NULL)
+			dumpnfa(nfa, f);
+	} while (progress && !NISERR());
+	if (NISERR())
+		return;
+
+	/*
+	 * Any ^ constraints we were able to pull to the start state can now be
+	 * replaced by PLAIN arcs referencing the BOS or BOL colors.  There should
+	 * be no other ^ or BEHIND arcs left in the NFA, though we do not check
+	 * that here (compact() will fail if so).
+	 */
+	for (a = nfa->pre->outs; a != NULL; a = nexta)
+	{
+		nexta = a->outchain;
+		if (a->type == '^')
+		{
+			assert(a->co == 0 || a->co == 1);
+			newarc(nfa, PLAIN, nfa->bos[a->co], a->from, a->to);
+			freearc(nfa, a);
+		}
+	}
+}
+
+/*
+ * pull - pull a back constraint backward past its source state
+ *
+ * Returns 1 if successful (which it always is unless the source is the
+ * start state or we have an internal error), 0 if nothing happened.
+ *
+ * A significant property of this function is that it deletes no pre-existing
+ * states, and no outarcs of the constraint's from state other than the given
+ * constraint arc.  This makes the loops in pullback() safe, at the cost that
+ * we may leave useless states behind.  Therefore, we leave it to pullback()
+ * to delete such states.
+ *
+ * If the from state has multiple back-constraint outarcs, and/or multiple
+ * compatible constraint inarcs, we only need to create one new intermediate
+ * state per combination of predecessor and successor states.  *intermediates
+ * points to a list of such intermediate states for this from state (chained
+ * through their tmp fields).
+ */
+static int
+pull(struct nfa *nfa,
+	 struct arc *con,
+	 struct state **intermediates)
+{
+	struct state *from = con->from;
+	struct state *to = con->to;
+	struct arc *a;
+	struct arc *nexta;
+	struct state *s;
+
+	assert(from != to);			/* should have gotten rid of this earlier */
+	if (from->flag)				/* can't pull back beyond start */
+		return 0;
+	if (from->nins == 0)
+	{							/* unreachable */
+		freearc(nfa, con);
+		return 1;
+	}
+
+	/*
+	 * First, clone from state if necessary to avoid other outarcs.  This may
+	 * seem wasteful, but it simplifies the logic, and we'll get rid of the
+	 * clone state again at the bottom.
+	 */
+	if (from->nouts > 1)
+	{
+		s = newstate(nfa);
+		if (NISERR())
+			return 0;
+		copyins(nfa, from, s);	/* duplicate inarcs */
+		cparc(nfa, con, s, to); /* move constraint arc */
+		freearc(nfa, con);
+		if (NISERR())
+			return 0;
+		from = s;
+		con = from->outs;
+	}
+	assert(from->nouts == 1);
+
+	/* propagate the constraint into the from state's inarcs */
+	for (a = from->ins; a != NULL && !NISERR(); a = nexta)
+	{
+		nexta = a->inchain;
+		switch (combine(nfa, con, a))
+		{
+			case INCOMPATIBLE:	/* destroy the arc */
+				freearc(nfa, a);
+				break;
+			case SATISFIED:		/* no action needed */
+				break;
+			case COMPATIBLE:	/* swap the two arcs, more or less */
+				/* need an intermediate state, but might have one already */
+				for (s = *intermediates; s != NULL; s = s->tmp)
+				{
+					assert(s->nins > 0 && s->nouts > 0);
+					if (s->ins->from == a->from && s->outs->to == to)
+						break;
+				}
+				if (s == NULL)
+				{
+					s = newstate(nfa);
+					if (NISERR())
+						return 0;
+					s->tmp = *intermediates;
+					*intermediates = s;
+				}
+				cparc(nfa, con, a->from, s);
+				cparc(nfa, a, s, to);
+				freearc(nfa, a);
+				break;
+			case REPLACEARC:	/* replace arc's color */
+				newarc(nfa, a->type, con->co, a->from, to);
+				freearc(nfa, a);
+				break;
+			default:
+				assert(NOTREACHED);
+				break;
+		}
+	}
+
+	/* remaining inarcs, if any, incorporate the constraint */
+	moveins(nfa, from, to);
+	freearc(nfa, con);
+	/* from state is now useless, but we leave it to pullback() to clean up */
+	return 1;
+}
+
+/*
+ * pushfwd - push forward constraints forward to eliminate them
+ */
+static void
+pushfwd(struct nfa *nfa,
+		FILE *f)				/* for debug output; NULL none */
+{
+	struct state *s;
+	struct state *nexts;
+	struct arc *a;
+	struct arc *nexta;
+	struct state *intermediates;
+	int			progress;
+
+	/* find and push until there are no more */
+	do
+	{
+		progress = 0;
+		for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
+		{
+			nexts = s->next;
+			intermediates = NULL;
+			for (a = s->ins; a != NULL && !NISERR(); a = nexta)
+			{
+				nexta = a->inchain;
+				if (a->type == '$' || a->type == AHEAD)
+					if (push(nfa, a, &intermediates))
+						progress = 1;
+			}
+			/* clear tmp fields of intermediate states created here */
+			while (intermediates != NULL)
+			{
+				struct state *ns = intermediates->tmp;
+
+				intermediates->tmp = NULL;
+				intermediates = ns;
+			}
+			/* if s is now useless, get rid of it */
+			if ((s->nins == 0 || s->nouts == 0) && !s->flag)
+				dropstate(nfa, s);
+		}
+		if (progress && f != NULL)
+			dumpnfa(nfa, f);
+	} while (progress && !NISERR());
+	if (NISERR())
+		return;
+
+	/*
+	 * Any $ constraints we were able to push to the post state can now be
+	 * replaced by PLAIN arcs referencing the EOS or EOL colors.  There should
+	 * be no other $ or AHEAD arcs left in the NFA, though we do not check
+	 * that here (compact() will fail if so).
+	 */
+	for (a = nfa->post->ins; a != NULL; a = nexta)
+	{
+		nexta = a->inchain;
+		if (a->type == '$')
+		{
+			assert(a->co == 0 || a->co == 1);
+			newarc(nfa, PLAIN, nfa->eos[a->co], a->from, a->to);
+			freearc(nfa, a);
+		}
+	}
+}
+
+/*
+ * push - push a forward constraint forward past its destination state
+ *
+ * Returns 1 if successful (which it always is unless the destination is the
+ * post state or we have an internal error), 0 if nothing happened.
+ *
+ * A significant property of this function is that it deletes no pre-existing
+ * states, and no inarcs of the constraint's to state other than the given
+ * constraint arc.  This makes the loops in pushfwd() safe, at the cost that
+ * we may leave useless states behind.  Therefore, we leave it to pushfwd()
+ * to delete such states.
+ *
+ * If the to state has multiple forward-constraint inarcs, and/or multiple
+ * compatible constraint outarcs, we only need to create one new intermediate
+ * state per combination of predecessor and successor states.  *intermediates
+ * points to a list of such intermediate states for this to state (chained
+ * through their tmp fields).
+ */
+static int
+push(struct nfa *nfa,
+	 struct arc *con,
+	 struct state **intermediates)
+{
+	struct state *from = con->from;
+	struct state *to = con->to;
+	struct arc *a;
+	struct arc *nexta;
+	struct state *s;
+
+	assert(to != from);			/* should have gotten rid of this earlier */
+	if (to->flag)				/* can't push forward beyond end */
+		return 0;
+	if (to->nouts == 0)
+	{							/* dead end */
+		freearc(nfa, con);
+		return 1;
+	}
+
+	/*
+	 * First, clone to state if necessary to avoid other inarcs.  This may
+	 * seem wasteful, but it simplifies the logic, and we'll get rid of the
+	 * clone state again at the bottom.
+	 */
+	if (to->nins > 1)
+	{
+		s = newstate(nfa);
+		if (NISERR())
+			return 0;
+		copyouts(nfa, to, s);	/* duplicate outarcs */
+		cparc(nfa, con, from, s);	/* move constraint arc */
+		freearc(nfa, con);
+		if (NISERR())
+			return 0;
+		to = s;
+		con = to->ins;
+	}
+	assert(to->nins == 1);
+
+	/* propagate the constraint into the to state's outarcs */
+	for (a = to->outs; a != NULL && !NISERR(); a = nexta)
+	{
+		nexta = a->outchain;
+		switch (combine(nfa, con, a))
+		{
+			case INCOMPATIBLE:	/* destroy the arc */
+				freearc(nfa, a);
+				break;
+			case SATISFIED:		/* no action needed */
+				break;
+			case COMPATIBLE:	/* swap the two arcs, more or less */
+				/* need an intermediate state, but might have one already */
+				for (s = *intermediates; s != NULL; s = s->tmp)
+				{
+					assert(s->nins > 0 && s->nouts > 0);
+					if (s->ins->from == from && s->outs->to == a->to)
+						break;
+				}
+				if (s == NULL)
+				{
+					s = newstate(nfa);
+					if (NISERR())
+						return 0;
+					s->tmp = *intermediates;
+					*intermediates = s;
+				}
+				cparc(nfa, con, s, a->to);
+				cparc(nfa, a, from, s);
+				freearc(nfa, a);
+				break;
+			case REPLACEARC:	/* replace arc's color */
+				newarc(nfa, a->type, con->co, from, a->to);
+				freearc(nfa, a);
+				break;
+			default:
+				assert(NOTREACHED);
+				break;
+		}
+	}
+
+	/* remaining outarcs, if any, incorporate the constraint */
+	moveouts(nfa, to, from);
+	freearc(nfa, con);
+	/* to state is now useless, but we leave it to pushfwd() to clean up */
+	return 1;
+}
+
+/*
+ * combine - constraint lands on an arc, what happens?
+ *
+ * #def INCOMPATIBLE	1	// destroys arc
+ * #def SATISFIED		2	// constraint satisfied
+ * #def COMPATIBLE		3	// compatible but not satisfied yet
+ * #def REPLACEARC		4	// replace arc's color with constraint color
+ */
+static int
+combine(struct nfa *nfa,
+		struct arc *con,
+		struct arc *a)
+{
+#define  CA(ct,at)	 (((ct)<<CHAR_BIT) | (at))
+
+	switch (CA(con->type, a->type))
+	{
+		case CA('^', PLAIN):	/* newlines are handled separately */
+		case CA('$', PLAIN):
+			return INCOMPATIBLE;
+			break;
+		case CA(AHEAD, PLAIN):	/* color constraints meet colors */
+		case CA(BEHIND, PLAIN):
+			if (con->co == a->co)
+				return SATISFIED;
+			if (con->co == RAINBOW)
+			{
+				/* con is satisfied unless arc's color is a pseudocolor */
+				if (!(nfa->cm->cd[a->co].flags & PSEUDO))
+					return SATISFIED;
+			}
+			else if (a->co == RAINBOW)
+			{
+				/* con is incompatible if it's for a pseudocolor */
+				if (nfa->cm->cd[con->co].flags & PSEUDO)
+					return INCOMPATIBLE;
+				/* otherwise, constraint constrains arc to be only its color */
+				return REPLACEARC;
+			}
+			return INCOMPATIBLE;
+			break;
+		case CA('^', '^'):		/* collision, similar constraints */
+		case CA('$', '$'):
+			if (con->co == a->co)	/* true duplication */
+				return SATISFIED;
+			return INCOMPATIBLE;
+			break;
+		case CA(AHEAD, AHEAD):	/* collision, similar constraints */
+		case CA(BEHIND, BEHIND):
+			if (con->co == a->co)	/* true duplication */
+				return SATISFIED;
+			if (con->co == RAINBOW)
+			{
+				/* con is satisfied unless arc's color is a pseudocolor */
+				if (!(nfa->cm->cd[a->co].flags & PSEUDO))
+					return SATISFIED;
+			}
+			else if (a->co == RAINBOW)
+			{
+				/* con is incompatible if it's for a pseudocolor */
+				if (nfa->cm->cd[con->co].flags & PSEUDO)
+					return INCOMPATIBLE;
+				/* otherwise, constraint constrains arc to be only its color */
+				return REPLACEARC;
+			}
+			return INCOMPATIBLE;
+			break;
+		case CA('^', BEHIND):	/* collision, dissimilar constraints */
+		case CA(BEHIND, '^'):
+		case CA('$', AHEAD):
+		case CA(AHEAD, '$'):
+			return INCOMPATIBLE;
+			break;
+		case CA('^', '$'):		/* constraints passing each other */
+		case CA('^', AHEAD):
+		case CA(BEHIND, '$'):
+		case CA(BEHIND, AHEAD):
+		case CA('$', '^'):
+		case CA('$', BEHIND):
+		case CA(AHEAD, '^'):
+		case CA(AHEAD, BEHIND):
+		case CA('^', LACON):
+		case CA(BEHIND, LACON):
+		case CA('$', LACON):
+		case CA(AHEAD, LACON):
+			return COMPATIBLE;
+			break;
+	}
+	assert(NOTREACHED);
+	return INCOMPATIBLE;		/* for benefit of blind compilers */
+}
+
+/*
+ * fixempties - get rid of EMPTY arcs
+ */
+static void
+fixempties(struct nfa *nfa,
+		   FILE *f)				/* for debug output; NULL none */
+{
+	struct state *s;
+	struct state *s2;
+	struct state *nexts;
+	struct arc *a;
+	struct arc *nexta;
+	int			totalinarcs;
+	struct arc **inarcsorig;
+	struct arc **arcarray;
+	int			arccount;
+	int			prevnins;
+	int			nskip;
+
+	/*
+	 * First, get rid of any states whose sole out-arc is an EMPTY, since
+	 * they're basically just aliases for their successor.  The parsing
+	 * algorithm creates enough of these that it's worth special-casing this.
+	 */
+	for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
+	{
+		nexts = s->next;
+		if (s->flag || s->nouts != 1)
+			continue;
+		a = s->outs;
+		assert(a != NULL && a->outchain == NULL);
+		if (a->type != EMPTY)
+			continue;
+		if (s != a->to)
+			moveins(nfa, s, a->to);
+		dropstate(nfa, s);
+	}
+
+	/*
+	 * Similarly, get rid of any state with a single EMPTY in-arc, by folding
+	 * it into its predecessor.
+	 */
+	for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
+	{
+		nexts = s->next;
+		/* while we're at it, ensure tmp fields are clear for next step */
+		assert(s->tmp == NULL);
+		if (s->flag || s->nins != 1)
+			continue;
+		a = s->ins;
+		assert(a != NULL && a->inchain == NULL);
+		if (a->type != EMPTY)
+			continue;
+		if (s != a->from)
+			moveouts(nfa, s, a->from);
+		dropstate(nfa, s);
+	}
+
+	if (NISERR())
+		return;
+
+	/*
+	 * For each remaining NFA state, find all other states from which it is
+	 * reachable by a chain of one or more EMPTY arcs.  Then generate new arcs
+	 * that eliminate the need for each such chain.
+	 *
+	 * We could replace a chain of EMPTY arcs that leads from a "from" state
+	 * to a "to" state either by pushing non-EMPTY arcs forward (linking
+	 * directly from "from"'s predecessors to "to") or by pulling them back
+	 * (linking directly from "from" to "to"'s successors).  We choose to
+	 * always do the former; this choice is somewhat arbitrary, but the
+	 * approach below requires that we uniformly do one or the other.
+	 *
+	 * Suppose we have a chain of N successive EMPTY arcs (where N can easily
+	 * approach the size of the NFA).  All of the intermediate states must
+	 * have additional inarcs and outarcs, else they'd have been removed by
+	 * the steps above.  Assuming their inarcs are mostly not empties, we will
+	 * add O(N^2) arcs to the NFA, since a non-EMPTY inarc leading to any one
+	 * state in the chain must be duplicated to lead to all its successor
+	 * states as well.  So there is no hope of doing less than O(N^2) work;
+	 * however, we should endeavor to keep the big-O cost from being even
+	 * worse than that, which it can easily become without care.  In
+	 * particular, suppose we were to copy all S1's inarcs forward to S2, and
+	 * then also to S3, and then later we consider pushing S2's inarcs forward
+	 * to S3.  If we include the arcs already copied from S1 in that, we'd be
+	 * doing O(N^3) work.  (The duplicate-arc elimination built into newarc()
+	 * and its cohorts would get rid of the extra arcs, but not without cost.)
+	 *
+	 * We can avoid this cost by treating only arcs that existed at the start
+	 * of this phase as candidates to be pushed forward.  To identify those,
+	 * we remember the first inarc each state had to start with.  We rely on
+	 * the fact that newarc() and friends put new arcs on the front of their
+	 * to-states' inchains, and that this phase never deletes arcs, so that
+	 * the original arcs must be the last arcs in their to-states' inchains.
+	 *
+	 * So the process here is that, for each state in the NFA, we gather up
+	 * all non-EMPTY inarcs of states that can reach the target state via
+	 * EMPTY arcs.  We then sort, de-duplicate, and merge these arcs into the
+	 * target state's inchain.  (We can safely use sort-merge for this as long
+	 * as we update each state's original-arcs pointer after we add arcs to
+	 * it; the sort step of mergeins probably changed the order of the old
+	 * arcs.)
+	 *
+	 * Another refinement worth making is that, because we only add non-EMPTY
+	 * arcs during this phase, and all added arcs have the same from-state as
+	 * the non-EMPTY arc they were cloned from, we know ahead of time that any
+	 * states having only EMPTY outarcs will be useless for lack of outarcs
+	 * after we drop the EMPTY arcs.  (They cannot gain non-EMPTY outarcs if
+	 * they had none to start with.)  So we need not bother to update the
+	 * inchains of such states at all.
+	 */
+
+	/* Remember the states' first original inarcs */
+	/* ... and while at it, count how many old inarcs there are altogether */
+	inarcsorig = (struct arc **) MALLOC(nfa->nstates * sizeof(struct arc *));
+	if (inarcsorig == NULL)
+	{
+		NERR(REG_ESPACE);
+		return;
+	}
+	totalinarcs = 0;
+	for (s = nfa->states; s != NULL; s = s->next)
+	{
+		inarcsorig[s->no] = s->ins;
+		totalinarcs += s->nins;
+	}
+
+	/*
+	 * Create a workspace for accumulating the inarcs to be added to the
+	 * current target state.  totalinarcs is probably a considerable
+	 * overestimate of the space needed, but the NFA is unlikely to be large
+	 * enough at this point to make it worth being smarter.
+	 */
+	arcarray = (struct arc **) MALLOC(totalinarcs * sizeof(struct arc *));
+	if (arcarray == NULL)
+	{
+		NERR(REG_ESPACE);
+		FREE(inarcsorig);
+		return;
+	}
+
+	/* And iterate over the target states */
+	for (s = nfa->states; s != NULL && !NISERR(); s = s->next)
+	{
+		/* Ignore target states without non-EMPTY outarcs, per note above */
+		if (!s->flag && !hasnonemptyout(s))
+			continue;
+
+		/* Find predecessor states and accumulate their original inarcs */
+		arccount = 0;
+		for (s2 = emptyreachable(nfa, s, s, inarcsorig); s2 != s; s2 = nexts)
+		{
+			/* Add s2's original inarcs to arcarray[], but ignore empties */
+			for (a = inarcsorig[s2->no]; a != NULL; a = a->inchain)
+			{
+				if (a->type != EMPTY)
+					arcarray[arccount++] = a;
+			}
+
+			/* Reset the tmp fields as we walk back */
+			nexts = s2->tmp;
+			s2->tmp = NULL;
+		}
+		s->tmp = NULL;
+		assert(arccount <= totalinarcs);
+
+		/* Remember how many original inarcs this state has */
+		prevnins = s->nins;
+
+		/* Add non-duplicate inarcs to target state */
+		mergeins(nfa, s, arcarray, arccount);
+
+		/* Now we must update the state's inarcsorig pointer */
+		nskip = s->nins - prevnins;
+		a = s->ins;
+		while (nskip-- > 0)
+			a = a->inchain;
+		inarcsorig[s->no] = a;
+	}
+
+	FREE(arcarray);
+	FREE(inarcsorig);
+
+	if (NISERR())
+		return;
+
+	/*
+	 * Now remove all the EMPTY arcs, since we don't need them anymore.
+	 */
+	for (s = nfa->states; s != NULL; s = s->next)
+	{
+		for (a = s->outs; a != NULL; a = nexta)
+		{
+			nexta = a->outchain;
+			if (a->type == EMPTY)
+				freearc(nfa, a);
+		}
+	}
+
+	/*
+	 * And remove any states that have become useless.  (This cleanup is not
+	 * very thorough, and would be even less so if we tried to combine it with
+	 * the previous step; but cleanup() will take care of anything we miss.)
+	 */
+	for (s = nfa->states; s != NULL; s = nexts)
+	{
+		nexts = s->next;
+		if ((s->nins == 0 || s->nouts == 0) && !s->flag)
+			dropstate(nfa, s);
+	}
+
+	if (f != NULL)
+		dumpnfa(nfa, f);
+}
+
+/*
+ * emptyreachable - recursively find all states that can reach s by EMPTY arcs
+ *
+ * The return value is the last such state found.  Its tmp field links back
+ * to the next-to-last such state, and so on back to s, so that all these
+ * states can be located without searching the whole NFA.
+ *
+ * Since this is only used in fixempties(), we pass in the inarcsorig[] array
+ * maintained by that function.  This lets us skip over all new inarcs, which
+ * are certainly not EMPTY arcs.
+ *
+ * The maximum recursion depth here is equal to the length of the longest
+ * loop-free chain of EMPTY arcs, which is surely no more than the size of
+ * the NFA ... but that could still be enough to cause trouble.
+ */
+static struct state *
+emptyreachable(struct nfa *nfa,
+			   struct state *s,
+			   struct state *lastfound,
+			   struct arc **inarcsorig)
+{
+	struct arc *a;
+
+	/* Since this is recursive, it could be driven to stack overflow */
+	if (STACK_TOO_DEEP(nfa->v->re))
+	{
+		NERR(REG_ETOOBIG);
+		return lastfound;
+	}
+
+	s->tmp = lastfound;
+	lastfound = s;
+	for (a = inarcsorig[s->no]; a != NULL; a = a->inchain)
+	{
+		if (a->type == EMPTY && a->from->tmp == NULL)
+			lastfound = emptyreachable(nfa, a->from, lastfound, inarcsorig);
+	}
+	return lastfound;
+}
+
+/*
+ * isconstraintarc - detect whether an arc is of a constraint type
+ */
+static inline int
+isconstraintarc(struct arc *a)
+{
+	switch (a->type)
+	{
+		case '^':
+		case '$':
+		case BEHIND:
+		case AHEAD:
+		case LACON:
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * hasconstraintout - does state have a constraint out arc?
+ */
+static int
+hasconstraintout(struct state *s)
+{
+	struct arc *a;
+
+	for (a = s->outs; a != NULL; a = a->outchain)
+	{
+		if (isconstraintarc(a))
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * fixconstraintloops - get rid of loops containing only constraint arcs
+ *
+ * A loop of states that contains only constraint arcs is useless, since
+ * passing around the loop represents no forward progress.  Moreover, it
+ * would cause infinite looping in pullback/pushfwd, so we need to get rid
+ * of such loops before doing that.
+ */
+static void
+fixconstraintloops(struct nfa *nfa,
+				   FILE *f)		/* for debug output; NULL none */
+{
+	struct state *s;
+	struct state *nexts;
+	struct arc *a;
+	struct arc *nexta;
+	int			hasconstraints;
+
+	/*
+	 * In the trivial case of a state that loops to itself, we can just drop
+	 * the constraint arc altogether.  This is worth special-casing because
+	 * such loops are far more common than loops containing multiple states.
+	 * While we're at it, note whether any constraint arcs survive.
+	 */
+	hasconstraints = 0;
+	for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
+	{
+		nexts = s->next;
+		/* while we're at it, ensure tmp fields are clear for next step */
+		assert(s->tmp == NULL);
+		for (a = s->outs; a != NULL && !NISERR(); a = nexta)
+		{
+			nexta = a->outchain;
+			if (isconstraintarc(a))
+			{
+				if (a->to == s)
+					freearc(nfa, a);
+				else
+					hasconstraints = 1;
+			}
+		}
+		/* If we removed all the outarcs, the state is useless. */
+		if (s->nouts == 0 && !s->flag)
+			dropstate(nfa, s);
+	}
+
+	/* Nothing to do if no remaining constraint arcs */
+	if (NISERR() || !hasconstraints)
+		return;
+
+	/*
+	 * Starting from each remaining NFA state, search outwards for a
+	 * constraint loop.  If we find a loop, break the loop, then start the
+	 * search over.  (We could possibly retain some state from the first scan,
+	 * but it would complicate things greatly, and multi-state constraint
+	 * loops are rare enough that it's not worth optimizing the case.)
+	 */
+restart:
+	for (s = nfa->states; s != NULL && !NISERR(); s = s->next)
+	{
+		if (findconstraintloop(nfa, s))
+			goto restart;
+	}
+
+	if (NISERR())
+		return;
+
+	/*
+	 * Now remove any states that have become useless.  (This cleanup is not
+	 * very thorough, and would be even less so if we tried to combine it with
+	 * the previous step; but cleanup() will take care of anything we miss.)
+	 *
+	 * Because findconstraintloop intentionally doesn't reset all tmp fields,
+	 * we have to clear them after it's done.  This is a convenient place to
+	 * do that, too.
+	 */
+	for (s = nfa->states; s != NULL; s = nexts)
+	{
+		nexts = s->next;
+		s->tmp = NULL;
+		if ((s->nins == 0 || s->nouts == 0) && !s->flag)
+			dropstate(nfa, s);
+	}
+
+	if (f != NULL)
+		dumpnfa(nfa, f);
+}
+
+/*
+ * findconstraintloop - recursively find a loop of constraint arcs
+ *
+ * If we find a loop, break it by calling breakconstraintloop(), then
+ * return 1; otherwise return 0.
+ *
+ * State tmp fields are guaranteed all NULL on a success return, because
+ * breakconstraintloop does that.  After a failure return, any state that
+ * is known not to be part of a loop is marked with s->tmp == s; this allows
+ * us not to have to re-prove that fact on later calls.  (This convention is
+ * workable because we already eliminated single-state loops.)
+ *
+ * Note that the found loop doesn't necessarily include the first state we
+ * are called on.  Any loop reachable from that state will do.
+ *
+ * The maximum recursion depth here is one more than the length of the longest
+ * loop-free chain of constraint arcs, which is surely no more than the size
+ * of the NFA ... but that could still be enough to cause trouble.
+ */
+static int
+findconstraintloop(struct nfa *nfa, struct state *s)
+{
+	struct arc *a;
+
+	/* Since this is recursive, it could be driven to stack overflow */
+	if (STACK_TOO_DEEP(nfa->v->re))
+	{
+		NERR(REG_ETOOBIG);
+		return 1;				/* to exit as quickly as possible */
+	}
+
+	if (s->tmp != NULL)
+	{
+		/* Already proven uninteresting? */
+		if (s->tmp == s)
+			return 0;
+		/* Found a loop involving s */
+		breakconstraintloop(nfa, s);
+		/* The tmp fields have been cleaned up by breakconstraintloop */
+		return 1;
+	}
+	for (a = s->outs; a != NULL; a = a->outchain)
+	{
+		if (isconstraintarc(a))
+		{
+			struct state *sto = a->to;
+
+			assert(sto != s);
+			s->tmp = sto;
+			if (findconstraintloop(nfa, sto))
+				return 1;
+		}
+	}
+
+	/*
+	 * If we get here, no constraint loop exists leading out from s.  Mark it
+	 * with s->tmp == s so we need not rediscover that fact again later.
+	 */
+	s->tmp = s;
+	return 0;
+}
+
+/*
+ * breakconstraintloop - break a loop of constraint arcs
+ *
+ * sinitial is any one member state of the loop.  Each loop member's tmp
+ * field links to its successor within the loop.  (Note that this function
+ * will reset all the tmp fields to NULL.)
+ *
+ * We can break the loop by, for any one state S1 in the loop, cloning its
+ * loop successor state S2 (and possibly following states), and then moving
+ * all S1->S2 constraint arcs to point to the cloned S2.  The cloned S2 should
+ * copy any non-constraint outarcs of S2.  Constraint outarcs should be
+ * dropped if they point back to S1, else they need to be copied as arcs to
+ * similarly cloned states S3, S4, etc.  In general, each cloned state copies
+ * non-constraint outarcs, drops constraint outarcs that would lead to itself
+ * or any earlier cloned state, and sends other constraint outarcs to newly
+ * cloned states.  No cloned state will have any inarcs that aren't constraint
+ * arcs or do not lead from S1 or earlier-cloned states.  It's okay to drop
+ * constraint back-arcs since they would not take us to any state we've not
+ * already been in; therefore, no new constraint loop is created.  In this way
+ * we generate a modified NFA that can still represent every useful state
+ * sequence, but not sequences that represent state loops with no consumption
+ * of input data.  Note that the set of cloned states will certainly include
+ * all of the loop member states other than S1, and it may also include
+ * non-loop states that are reachable from S2 via constraint arcs.  This is
+ * important because there is no guarantee that findconstraintloop found a
+ * maximal loop (and searching for one would be NP-hard, so don't try).
+ * Frequently the "non-loop states" are actually part of a larger loop that
+ * we didn't notice, and indeed there may be several overlapping loops.
+ * This technique ensures convergence in such cases, while considering only
+ * the originally-found loop does not.
+ *
+ * If there is only one S1->S2 constraint arc, then that constraint is
+ * certainly satisfied when we enter any of the clone states.  This means that
+ * in the common case where many of the constraint arcs are identically
+ * labeled, we can merge together clone states linked by a similarly-labeled
+ * constraint: if we can get to the first one we can certainly get to the
+ * second, so there's no need to distinguish.  This greatly reduces the number
+ * of new states needed, so we preferentially break the given loop at a state
+ * pair where this is true.
+ *
+ * Furthermore, it's fairly common to find that a cloned successor state has
+ * no outarcs, especially if we're a bit aggressive about removing unnecessary
+ * outarcs.  If that happens, then there is simply not any interesting state
+ * that can be reached through the predecessor's loop arcs, which means we can
+ * break the loop just by removing those loop arcs, with no new states added.
+ */
+static void
+breakconstraintloop(struct nfa *nfa, struct state *sinitial)
+{
+	struct state *s;
+	struct state *shead;
+	struct state *stail;
+	struct state *sclone;
+	struct state *nexts;
+	struct arc *refarc;
+	struct arc *a;
+	struct arc *nexta;
+
+	/*
+	 * Start by identifying which loop step we want to break at.
+	 * Preferentially this is one with only one constraint arc.  (XXX are
+	 * there any other secondary heuristics we want to use here?)  Set refarc
+	 * to point to the selected lone constraint arc, if there is one.
+	 */
+	refarc = NULL;
+	s = sinitial;
+	do
+	{
+		nexts = s->tmp;
+		assert(nexts != s);		/* should not see any one-element loops */
+		if (refarc == NULL)
+		{
+			int			narcs = 0;
+
+			for (a = s->outs; a != NULL; a = a->outchain)
+			{
+				if (a->to == nexts && isconstraintarc(a))
+				{
+					refarc = a;
+					narcs++;
+				}
+			}
+			assert(narcs > 0);
+			if (narcs > 1)
+				refarc = NULL;	/* multiple constraint arcs here, no good */
+		}
+		s = nexts;
+	} while (s != sinitial);
+
+	if (refarc)
+	{
+		/* break at the refarc */
+		shead = refarc->from;
+		stail = refarc->to;
+		assert(stail == shead->tmp);
+	}
+	else
+	{
+		/* for lack of a better idea, break after sinitial */
+		shead = sinitial;
+		stail = sinitial->tmp;
+	}
+
+	/*
+	 * Reset the tmp fields so that we can use them for local storage in
+	 * clonesuccessorstates.  (findconstraintloop won't mind, since it's just
+	 * going to abandon its search anyway.)
+	 */
+	for (s = nfa->states; s != NULL; s = s->next)
+		s->tmp = NULL;
+
+	/*
+	 * Recursively build clone state(s) as needed.
+	 */
+	sclone = newstate(nfa);
+	if (sclone == NULL)
+	{
+		assert(NISERR());
+		return;
+	}
+
+	clonesuccessorstates(nfa, stail, sclone, shead, refarc,
+						 NULL, NULL, nfa->nstates);
+
+	if (NISERR())
+		return;
+
+	/*
+	 * It's possible that sclone has no outarcs at all, in which case it's
+	 * useless.  (We don't try extremely hard to get rid of useless states
+	 * here, but this is an easy and fairly common case.)
+	 */
+	if (sclone->nouts == 0)
+	{
+		freestate(nfa, sclone);
+		sclone = NULL;
+	}
+
+	/*
+	 * Move shead's constraint-loop arcs to point to sclone, or just drop them
+	 * if we discovered we don't need sclone.
+	 */
+	for (a = shead->outs; a != NULL; a = nexta)
+	{
+		nexta = a->outchain;
+		if (a->to == stail && isconstraintarc(a))
+		{
+			if (sclone)
+				cparc(nfa, a, shead, sclone);
+			freearc(nfa, a);
+			if (NISERR())
+				break;
+		}
+	}
+}
+
+/*
+ * clonesuccessorstates - create a tree of constraint-arc successor states
+ *
+ * ssource is the state to be cloned, and sclone is the state to copy its
+ * outarcs into.  sclone's inarcs, if any, should already be set up.
+ *
+ * spredecessor is the original predecessor state that we are trying to build
+ * successors for (it may not be the immediate predecessor of ssource).
+ * refarc, if not NULL, is the original constraint arc that is known to have
+ * been traversed out of spredecessor to reach the successor(s).
+ *
+ * For each cloned successor state, we transiently create a "donemap" that is
+ * a boolean array showing which source states we've already visited for this
+ * clone state.  This prevents infinite recursion as well as useless repeat
+ * visits to the same state subtree (which can add up fast, since typical NFAs
+ * have multiple redundant arc pathways).  Each donemap is a char array
+ * indexed by state number.  The donemaps are all of the same size "nstates",
+ * which is nfa->nstates as of the start of the recursion.  This is enough to
+ * have entries for all pre-existing states, but *not* entries for clone
+ * states created during the recursion.  That's okay since we have no need to
+ * mark those.
+ *
+ * curdonemap is NULL when recursing to a new sclone state, or sclone's
+ * donemap when we are recursing without having created a new state (which we
+ * do when we decide we can merge a successor state into the current clone
+ * state).  outerdonemap is NULL at the top level and otherwise the parent
+ * clone state's donemap.
+ *
+ * The successor states we create and fill here form a strict tree structure,
+ * with each state having exactly one predecessor, except that the toplevel
+ * state has no inarcs as yet (breakconstraintloop will add its inarcs from
+ * spredecessor after we're done).  Thus, we can examine sclone's inarcs back
+ * to the root, plus refarc if any, to identify the set of constraints already
+ * known valid at the current point.  This allows us to avoid generating extra
+ * successor states.
+ */
+static void
+clonesuccessorstates(struct nfa *nfa,
+					 struct state *ssource,
+					 struct state *sclone,
+					 struct state *spredecessor,
+					 struct arc *refarc,
+					 char *curdonemap,
+					 char *outerdonemap,
+					 int nstates)
+{
+	char	   *donemap;
+	struct arc *a;
+
+	/* Since this is recursive, it could be driven to stack overflow */
+	if (STACK_TOO_DEEP(nfa->v->re))
+	{
+		NERR(REG_ETOOBIG);
+		return;
+	}
+
+	/* If this state hasn't already got a donemap, create one */
+	donemap = curdonemap;
+	if (donemap == NULL)
+	{
+		donemap = (char *) MALLOC(nstates * sizeof(char));
+		if (donemap == NULL)
+		{
+			NERR(REG_ESPACE);
+			return;
+		}
+
+		if (outerdonemap != NULL)
+		{
+			/*
+			 * Not at outermost recursion level, so copy the outer level's
+			 * donemap; this ensures that we see states in process of being
+			 * visited at outer levels, or already merged into predecessor
+			 * states, as ones we shouldn't traverse back to.
+			 */
+			memcpy(donemap, outerdonemap, nstates * sizeof(char));
+		}
+		else
+		{
+			/* At outermost level, only spredecessor is off-limits */
+			memset(donemap, 0, nstates * sizeof(char));
+			assert(spredecessor->no < nstates);
+			donemap[spredecessor->no] = 1;
+		}
+	}
+
+	/* Mark ssource as visited in the donemap */
+	assert(ssource->no < nstates);
+	assert(donemap[ssource->no] == 0);
+	donemap[ssource->no] = 1;
+
+	/*
+	 * We proceed by first cloning all of ssource's outarcs, creating new
+	 * clone states as needed but not doing more with them than that.  Then in
+	 * a second pass, recurse to process the child clone states.  This allows
+	 * us to have only one child clone state per reachable source state, even
+	 * when there are multiple outarcs leading to the same state.  Also, when
+	 * we do visit a child state, its set of inarcs is known exactly, which
+	 * makes it safe to apply the constraint-is-already-checked optimization.
+	 * Also, this ensures that we've merged all the states we can into the
+	 * current clone before we recurse to any children, thus possibly saving
+	 * them from making extra images of those states.
+	 *
+	 * While this function runs, child clone states of the current state are
+	 * marked by setting their tmp fields to point to the original state they
+	 * were cloned from.  This makes it possible to detect multiple outarcs
+	 * leading to the same state, and also makes it easy to distinguish clone
+	 * states from original states (which will have tmp == NULL).
+	 */
+	for (a = ssource->outs; a != NULL && !NISERR(); a = a->outchain)
+	{
+		struct state *sto = a->to;
+
+		/*
+		 * We do not consider cloning successor states that have no constraint
+		 * outarcs; just link to them as-is.  They cannot be part of a
+		 * constraint loop so there is no need to make copies.  In particular,
+		 * this rule keeps us from trying to clone the post state, which would
+		 * be a bad idea.
+		 */
+		if (isconstraintarc(a) && hasconstraintout(sto))
+		{
+			struct state *prevclone;
+			int			canmerge;
+			struct arc *a2;
+
+			/*
+			 * Back-link constraint arcs must not be followed.  Nor is there a
+			 * need to revisit states previously merged into this clone.
+			 */
+			assert(sto->no < nstates);
+			if (donemap[sto->no] != 0)
+				continue;
+
+			/*
+			 * Check whether we already have a child clone state for this
+			 * source state.
+			 */
+			prevclone = NULL;
+			for (a2 = sclone->outs; a2 != NULL; a2 = a2->outchain)
+			{
+				if (a2->to->tmp == sto)
+				{
+					prevclone = a2->to;
+					break;
+				}
+			}
+
+			/*
+			 * If this arc is labeled the same as refarc, or the same as any
+			 * arc we must have traversed to get to sclone, then no additional
+			 * constraints need to be met to get to sto, so we should just
+			 * merge its outarcs into sclone.
+			 */
+			if (refarc && a->type == refarc->type && a->co == refarc->co)
+				canmerge = 1;
+			else
+			{
+				struct state *s;
+
+				canmerge = 0;
+				for (s = sclone; s->ins; s = s->ins->from)
+				{
+					if (s->nins == 1 &&
+						a->type == s->ins->type && a->co == s->ins->co)
+					{
+						canmerge = 1;
+						break;
+					}
+				}
+			}
+
+			if (canmerge)
+			{
+				/*
+				 * We can merge into sclone.  If we previously made a child
+				 * clone state, drop it; there's no need to visit it.  (This
+				 * can happen if ssource has multiple pathways to sto, and we
+				 * only just now found one that is provably a no-op.)
+				 */
+				if (prevclone)
+					dropstate(nfa, prevclone);	/* kills our outarc, too */
+
+				/* Recurse to merge sto's outarcs into sclone */
+				clonesuccessorstates(nfa,
+									 sto,
+									 sclone,
+									 spredecessor,
+									 refarc,
+									 donemap,
+									 outerdonemap,
+									 nstates);
+				/* sto should now be marked as previously visited */
+				assert(NISERR() || donemap[sto->no] == 1);
+			}
+			else if (prevclone)
+			{
+				/*
+				 * We already have a clone state for this successor, so just
+				 * make another arc to it.
+				 */
+				cparc(nfa, a, sclone, prevclone);
+			}
+			else
+			{
+				/*
+				 * We need to create a new successor clone state.
+				 */
+				struct state *stoclone;
+
+				stoclone = newstate(nfa);
+				if (stoclone == NULL)
+				{
+					assert(NISERR());
+					break;
+				}
+				/* Mark it as to what it's a clone of */
+				stoclone->tmp = sto;
+				/* ... and add the outarc leading to it */
+				cparc(nfa, a, sclone, stoclone);
+			}
+		}
+		else
+		{
+			/*
+			 * Non-constraint outarcs just get copied to sclone, as do outarcs
+			 * leading to states with no constraint outarc.
+			 */
+			cparc(nfa, a, sclone, sto);
+		}
+	}
+
+	/*
+	 * If we are at outer level for this clone state, recurse to all its child
+	 * clone states, clearing their tmp fields as we go.  (If we're not
+	 * outermost for sclone, leave this to be done by the outer call level.)
+	 * Note that if we have multiple outarcs leading to the same clone state,
+	 * it will only be recursed-to once.
+	 */
+	if (curdonemap == NULL)
+	{
+		for (a = sclone->outs; a != NULL && !NISERR(); a = a->outchain)
+		{
+			struct state *stoclone = a->to;
+			struct state *sto = stoclone->tmp;
+
+			if (sto != NULL)
+			{
+				stoclone->tmp = NULL;
+				clonesuccessorstates(nfa,
+									 sto,
+									 stoclone,
+									 spredecessor,
+									 refarc,
+									 NULL,
+									 donemap,
+									 nstates);
+			}
+		}
+
+		/* Don't forget to free sclone's donemap when done with it */
+		FREE(donemap);
+	}
+}
+
+/*
+ * cleanup - clean up NFA after optimizations
+ */
+static void
+cleanup(struct nfa *nfa)
+{
+	struct state *s;
+	struct state *nexts;
+	int			n;
+
+	if (NISERR())
+		return;
+
+	/* clear out unreachable or dead-end states */
+	/* use pre to mark reachable, then post to mark can-reach-post */
+	markreachable(nfa, nfa->pre, (struct state *) NULL, nfa->pre);
+	markcanreach(nfa, nfa->post, nfa->pre, nfa->post);
+	for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
+	{
+		nexts = s->next;
+		if (s->tmp != nfa->post && !s->flag)
+			dropstate(nfa, s);
+	}
+	assert(NISERR() || nfa->post->nins == 0 || nfa->post->tmp == nfa->post);
+	cleartraverse(nfa, nfa->pre);
+	assert(NISERR() || nfa->post->nins == 0 || nfa->post->tmp == NULL);
+	/* the nins==0 (final unreachable) case will be caught later */
+
+	/* renumber surviving states */
+	n = 0;
+	for (s = nfa->states; s != NULL; s = s->next)
+		s->no = n++;
+	nfa->nstates = n;
+}
+
+/*
+ * markreachable - recursive marking of reachable states
+ */
+static void
+markreachable(struct nfa *nfa,
+			  struct state *s,
+			  struct state *okay,	/* consider only states with this mark */
+			  struct state *mark)	/* the value to mark with */
+{
+	struct arc *a;
+
+	/* Since this is recursive, it could be driven to stack overflow */
+	if (STACK_TOO_DEEP(nfa->v->re))
+	{
+		NERR(REG_ETOOBIG);
+		return;
+	}
+
+	if (s->tmp != okay)
+		return;
+	s->tmp = mark;
+
+	for (a = s->outs; a != NULL; a = a->outchain)
+		markreachable(nfa, a->to, okay, mark);
+}
+
+/*
+ * markcanreach - recursive marking of states which can reach here
+ */
+static void
+markcanreach(struct nfa *nfa,
+			 struct state *s,
+			 struct state *okay,	/* consider only states with this mark */
+			 struct state *mark)	/* the value to mark with */
+{
+	struct arc *a;
+
+	/* Since this is recursive, it could be driven to stack overflow */
+	if (STACK_TOO_DEEP(nfa->v->re))
+	{
+		NERR(REG_ETOOBIG);
+		return;
+	}
+
+	if (s->tmp != okay)
+		return;
+	s->tmp = mark;
+
+	for (a = s->ins; a != NULL; a = a->inchain)
+		markcanreach(nfa, a->from, okay, mark);
+}
+
+/*
+ * analyze - ascertain potentially-useful facts about an optimized NFA
+ */
+static long						/* re_info bits to be ORed in */
+analyze(struct nfa *nfa)
+{
+	struct arc *a;
+	struct arc *aa;
+
+	if (NISERR())
+		return 0;
+
+	/* Detect whether NFA can't match anything */
+	if (nfa->pre->outs == NULL)
+		return REG_UIMPOSSIBLE;
+
+	/* Detect whether NFA matches all strings (possibly with length bounds) */
+	checkmatchall(nfa);
+
+	/* Detect whether NFA can possibly match a zero-length string */
+	for (a = nfa->pre->outs; a != NULL; a = a->outchain)
+		for (aa = a->to->outs; aa != NULL; aa = aa->outchain)
+			if (aa->to == nfa->post)
+				return REG_UEMPTYMATCH;
+	return 0;
+}
+
+/*
+ * checkmatchall - does the NFA represent no more than a string length test?
+ *
+ * If so, set nfa->minmatchall and nfa->maxmatchall correctly (they are -1
+ * to begin with) and set the MATCHALL bit in nfa->flags.
+ *
+ * To succeed, we require all arcs to be PLAIN RAINBOW arcs, except for those
+ * for pseudocolors (i.e., BOS/BOL/EOS/EOL).  We must be able to reach the
+ * post state via RAINBOW arcs, and if there are any loops in the graph, they
+ * must be loop-to-self arcs, ensuring that each loop iteration consumes
+ * exactly one character.  (Longer loops are problematic because they create
+ * non-consecutive possible match lengths; we have no good way to represent
+ * that situation for lengths beyond the DUPINF limit.)
+ *
+ * Pseudocolor arcs complicate things a little.  We know that they can only
+ * appear as pre-state outarcs (for BOS/BOL) or post-state inarcs (for
+ * EOS/EOL).  There, they must exactly replicate the parallel RAINBOW arcs,
+ * e.g. if the pre state has one RAINBOW outarc to state 2, it must have BOS
+ * and BOL outarcs to state 2, and no others.  Missing or extra pseudocolor
+ * arcs can occur, meaning that the NFA involves some constraint on the
+ * adjacent characters, which makes it not a matchall NFA.
+ */
+static void
+checkmatchall(struct nfa *nfa)
+{
+	bool	  **haspaths;
+	struct state *s;
+	int			i;
+
+	/*
+	 * If there are too many states, don't bother trying to detect matchall.
+	 * This limit serves to bound the time and memory we could consume below.
+	 * Note that even if the graph is all-RAINBOW, if there are significantly
+	 * more than DUPINF states then it's likely that there are paths of length
+	 * more than DUPINF, which would force us to fail anyhow.  In practice,
+	 * plausible ways of writing a matchall regex with maximum finite path
+	 * length K tend not to have very many more than K states.
+	 */
+	if (nfa->nstates > DUPINF * 2)
+		return;
+
+	/*
+	 * First, scan all the states to verify that only RAINBOW arcs appear,
+	 * plus pseudocolor arcs adjacent to the pre and post states.  This lets
+	 * us quickly eliminate most cases that aren't matchall NFAs.
+	 */
+	for (s = nfa->states; s != NULL; s = s->next)
+	{
+		struct arc *a;
+
+		for (a = s->outs; a != NULL; a = a->outchain)
+		{
+			if (a->type != PLAIN)
+				return;			/* any LACONs make it non-matchall */
+			if (a->co != RAINBOW)
+			{
+				if (nfa->cm->cd[a->co].flags & PSEUDO)
+				{
+					/*
+					 * Pseudocolor arc: verify it's in a valid place (this
+					 * seems quite unlikely to fail, but let's be sure).
+					 */
+					if (s == nfa->pre &&
+						(a->co == nfa->bos[0] || a->co == nfa->bos[1]))
+						 /* okay BOS/BOL arc */ ;
+					else if (a->to == nfa->post &&
+							 (a->co == nfa->eos[0] || a->co == nfa->eos[1]))
+						 /* okay EOS/EOL arc */ ;
+					else
+						return; /* unexpected pseudocolor arc */
+					/* We'll check these arcs some more below. */
+				}
+				else
+					return;		/* any other color makes it non-matchall */
+			}
+		}
+		/* Also, assert that the tmp fields are available for use. */
+		assert(s->tmp == NULL);
+	}
+
+	/*
+	 * The next cheapest check we can make is to verify that the BOS/BOL
+	 * outarcs of the pre state reach the same states as its RAINBOW outarcs.
+	 * If they don't, the NFA expresses some constraints on the character
+	 * before the matched string, making it non-matchall.  Likewise, the
+	 * EOS/EOL inarcs of the post state must match its RAINBOW inarcs.
+	 */
+	if (!check_out_colors_match(nfa->pre, RAINBOW, nfa->bos[0]) ||
+		!check_out_colors_match(nfa->pre, RAINBOW, nfa->bos[1]) ||
+		!check_in_colors_match(nfa->post, RAINBOW, nfa->eos[0]) ||
+		!check_in_colors_match(nfa->post, RAINBOW, nfa->eos[1]))
+		return;
+
+	/*
+	 * Initialize an array of path-length arrays, in which
+	 * checkmatchall_recurse will return per-state results.  This lets us
+	 * memo-ize the recursive search and avoid exponential time consumption.
+	 */
+	haspaths = (bool **) MALLOC(nfa->nstates * sizeof(bool *));
+	if (haspaths == NULL)
+		return;					/* fail quietly */
+	memset(haspaths, 0, nfa->nstates * sizeof(bool *));
+
+	/*
+	 * Recursively search the graph for all-RAINBOW paths to the "post" state,
+	 * starting at the "pre" state, and computing the lengths of the paths.
+	 * (Given the preceding checks, there should be at least one such path.
+	 * However we could get back a false result anyway, in case there are
+	 * multi-state loops, paths exceeding DUPINF+1 length, or non-algorithmic
+	 * failures such as ENOMEM.)
+	 */
+	if (checkmatchall_recurse(nfa, nfa->pre, haspaths))
+	{
+		/* The useful result is the path length array for the pre state */
+		bool	   *haspath = haspaths[nfa->pre->no];
+		int			minmatch,
+					maxmatch,
+					morematch;
+
+		assert(haspath != NULL);
+
+		/*
+		 * haspath[] now represents the set of possible path lengths; but we
+		 * want to reduce that to a min and max value, because it doesn't seem
+		 * worth complicating regexec.c to deal with nonconsecutive possible
+		 * match lengths.  Find min and max of first run of lengths, then
+		 * verify there are no nonconsecutive lengths.
+		 */
+		for (minmatch = 0; minmatch <= DUPINF + 1; minmatch++)
+		{
+			if (haspath[minmatch])
+				break;
+		}
+		assert(minmatch <= DUPINF + 1); /* else checkmatchall_recurse lied */
+		for (maxmatch = minmatch; maxmatch < DUPINF + 1; maxmatch++)
+		{
+			if (!haspath[maxmatch + 1])
+				break;
+		}
+		for (morematch = maxmatch + 1; morematch <= DUPINF + 1; morematch++)
+		{
+			if (haspath[morematch])
+			{
+				haspath = NULL; /* fail, there are nonconsecutive lengths */
+				break;
+			}
+		}
+
+		if (haspath != NULL)
+		{
+			/*
+			 * Success, so record the info.  Here we have a fine point: the
+			 * path length from the pre state includes the pre-to-initial
+			 * transition, so it's one more than the actually matched string
+			 * length.  (We avoided counting the final-to-post transition
+			 * within checkmatchall_recurse, but not this one.)  This is why
+			 * checkmatchall_recurse allows one more level of path length than
+			 * might seem necessary.  This decrement also takes care of
+			 * converting checkmatchall_recurse's definition of "infinity" as
+			 * "DUPINF+1" to our normal representation as "DUPINF".
+			 */
+			assert(minmatch > 0);	/* else pre and post states were adjacent */
+			nfa->minmatchall = minmatch - 1;
+			nfa->maxmatchall = maxmatch - 1;
+			nfa->flags |= MATCHALL;
+		}
+	}
+
+	/* Clean up */
+	for (i = 0; i < nfa->nstates; i++)
+	{
+		if (haspaths[i] != NULL)
+			FREE(haspaths[i]);
+	}
+	FREE(haspaths);
+}
+
+/*
+ * checkmatchall_recurse - recursive search for checkmatchall
+ *
+ * s is the state to be examined in this recursion level.
+ * haspaths[] is an array of per-state exit path length arrays.
+ *
+ * We return true if the search was performed successfully, false if
+ * we had to fail because of multi-state loops or other internal reasons.
+ * (Because "dead" states that can't reach the post state have been
+ * eliminated, and we already verified that only RAINBOW and matching
+ * pseudocolor arcs exist, every state should have RAINBOW path(s) to
+ * the post state.  Hence we take a false result from recursive calls
+ * as meaning that we'd better fail altogether, not just that that
+ * particular state can't reach the post state.)
+ *
+ * On success, we store a malloc'd result array in haspaths[s->no],
+ * showing the possible path lengths from s to the post state.
+ * Each state's haspath[] array is of length DUPINF+2.  The entries from
+ * k = 0 to DUPINF are true if there is an all-RAINBOW path of length k
+ * from this state to the string end.  haspath[DUPINF+1] is true if all
+ * path lengths >= DUPINF+1 are possible.  (Situations that cannot be
+ * represented under these rules cause failure.)
+ *
+ * checkmatchall is responsible for eventually freeing the haspath[] arrays.
+ */
+static bool
+checkmatchall_recurse(struct nfa *nfa, struct state *s, bool **haspaths)
+{
+	bool		result = false;
+	bool		foundloop = false;
+	bool	   *haspath;
+	struct arc *a;
+
+	/*
+	 * Since this is recursive, it could be driven to stack overflow.  But we
+	 * need not treat that as a hard failure; just deem the NFA non-matchall.
+	 */
+	if (STACK_TOO_DEEP(nfa->v->re))
+		return false;
+
+	/* In case the search takes a long time, check for cancel */
+	if (CANCEL_REQUESTED(nfa->v->re))
+	{
+		NERR(REG_CANCEL);
+		return false;
+	}
+
+	/* Create a haspath array for this state */
+	haspath = (bool *) MALLOC((DUPINF + 2) * sizeof(bool));
+	if (haspath == NULL)
+		return false;			/* again, treat as non-matchall */
+	memset(haspath, 0, (DUPINF + 2) * sizeof(bool));
+
+	/* Mark this state as being visited */
+	assert(s->tmp == NULL);
+	s->tmp = s;
+
+	for (a = s->outs; a != NULL; a = a->outchain)
+	{
+		if (a->co != RAINBOW)
+			continue;			/* ignore pseudocolor arcs */
+		if (a->to == nfa->post)
+		{
+			/* We found an all-RAINBOW path to the post state */
+			result = true;
+
+			/*
+			 * Mark this state as being zero steps away from the string end
+			 * (the transition to the post state isn't counted).
+			 */
+			haspath[0] = true;
+		}
+		else if (a->to == s)
+		{
+			/* We found a cycle of length 1, which we'll deal with below. */
+			foundloop = true;
+		}
+		else if (a->to->tmp != NULL)
+		{
+			/* It's busy, so we found a cycle of length > 1, so fail. */
+			result = false;
+			break;
+		}
+		else
+		{
+			/* Consider paths forward through this to-state. */
+			bool	   *nexthaspath;
+			int			i;
+
+			/* If to-state was not already visited, recurse */
+			if (haspaths[a->to->no] == NULL)
+			{
+				result = checkmatchall_recurse(nfa, a->to, haspaths);
+				/* Fail if any recursive path fails */
+				if (!result)
+					break;
+			}
+			else
+			{
+				/* The previous visit must have found path(s) to the end */
+				result = true;
+			}
+			assert(a->to->tmp == NULL);
+			nexthaspath = haspaths[a->to->no];
+			assert(nexthaspath != NULL);
+
+			/*
+			 * Now, for every path of length i from a->to to the string end,
+			 * there is a path of length i + 1 from s to the string end.
+			 */
+			if (nexthaspath[DUPINF] != nexthaspath[DUPINF + 1])
+			{
+				/*
+				 * a->to has a path of length exactly DUPINF, but not longer;
+				 * or it has paths of all lengths > DUPINF but not one of
+				 * exactly that length.  In either case, we cannot represent
+				 * the possible path lengths from s correctly, so fail.
+				 */
+				result = false;
+				break;
+			}
+			/* Merge knowledge of these path lengths into what we have */
+			for (i = 0; i < DUPINF; i++)
+				haspath[i + 1] |= nexthaspath[i];
+			/* Infinity + 1 is still infinity */
+			haspath[DUPINF + 1] |= nexthaspath[DUPINF + 1];
+		}
+	}
+
+	if (result && foundloop)
+	{
+		/*
+		 * If there is a length-1 loop at this state, then find the shortest
+		 * known path length to the end.  The loop means that every larger
+		 * path length is possible, too.  (It doesn't matter whether any of
+		 * the longer lengths were already known possible.)
+		 */
+		int			i;
+
+		for (i = 0; i <= DUPINF; i++)
+		{
+			if (haspath[i])
+				break;
+		}
+		for (i++; i <= DUPINF + 1; i++)
+			haspath[i] = true;
+	}
+
+	/* Report out the completed path length map */
+	assert(s->no < nfa->nstates);
+	assert(haspaths[s->no] == NULL);
+	haspaths[s->no] = haspath;
+
+	/* Mark state no longer busy */
+	s->tmp = NULL;
+
+	return result;
+}
+
+/*
+ * check_out_colors_match - subroutine for checkmatchall
+ *
+ * Check whether the set of states reachable from s by arcs of color co1
+ * is equivalent to the set reachable by arcs of color co2.
+ * checkmatchall already verified that all of the NFA's arcs are PLAIN,
+ * so we need not examine arc types here.
+ */
+static bool
+check_out_colors_match(struct state *s, color co1, color co2)
+{
+	bool		result = true;
+	struct arc *a;
+
+	/*
+	 * To do this in linear time, we assume that the NFA contains no duplicate
+	 * arcs.  Run through the out-arcs, marking states reachable by arcs of
+	 * color co1.  Run through again, un-marking states reachable by arcs of
+	 * color co2; if we see a not-marked state, we know this co2 arc is
+	 * unmatched.  Then run through again, checking for still-marked states,
+	 * and in any case leaving all the tmp fields reset to NULL.
+	 */
+	for (a = s->outs; a != NULL; a = a->outchain)
+	{
+		if (a->co == co1)
+		{
+			assert(a->to->tmp == NULL);
+			a->to->tmp = a->to;
+		}
+	}
+	for (a = s->outs; a != NULL; a = a->outchain)
+	{
+		if (a->co == co2)
+		{
+			if (a->to->tmp != NULL)
+				a->to->tmp = NULL;
+			else
+				result = false; /* unmatched co2 arc */
+		}
+	}
+	for (a = s->outs; a != NULL; a = a->outchain)
+	{
+		if (a->co == co1)
+		{
+			if (a->to->tmp != NULL)
+			{
+				result = false; /* unmatched co1 arc */
+				a->to->tmp = NULL;
+			}
+		}
+	}
+	return result;
+}
+
+/*
+ * check_in_colors_match - subroutine for checkmatchall
+ *
+ * Check whether the set of states that can reach s by arcs of color co1
+ * is equivalent to the set that can reach s by arcs of color co2.
+ * checkmatchall already verified that all of the NFA's arcs are PLAIN,
+ * so we need not examine arc types here.
+ */
+static bool
+check_in_colors_match(struct state *s, color co1, color co2)
+{
+	bool		result = true;
+	struct arc *a;
+
+	/*
+	 * Identical algorithm to check_out_colors_match, except examine the
+	 * from-states of s' inarcs.
+	 */
+	for (a = s->ins; a != NULL; a = a->inchain)
+	{
+		if (a->co == co1)
+		{
+			assert(a->from->tmp == NULL);
+			a->from->tmp = a->from;
+		}
+	}
+	for (a = s->ins; a != NULL; a = a->inchain)
+	{
+		if (a->co == co2)
+		{
+			if (a->from->tmp != NULL)
+				a->from->tmp = NULL;
+			else
+				result = false; /* unmatched co2 arc */
+		}
+	}
+	for (a = s->ins; a != NULL; a = a->inchain)
+	{
+		if (a->co == co1)
+		{
+			if (a->from->tmp != NULL)
+			{
+				result = false; /* unmatched co1 arc */
+				a->from->tmp = NULL;
+			}
+		}
+	}
+	return result;
+}
+
+/*
+ * compact - construct the compact representation of an NFA
+ */
+static void
+compact(struct nfa *nfa,
+		struct cnfa *cnfa)
+{
+	struct state *s;
+	struct arc *a;
+	size_t		nstates;
+	size_t		narcs;
+	struct carc *ca;
+	struct carc *first;
+
+	assert(!NISERR());
+
+	nstates = 0;
+	narcs = 0;
+	for (s = nfa->states; s != NULL; s = s->next)
+	{
+		nstates++;
+		narcs += s->nouts + 1;	/* need one extra for endmarker */
+	}
+
+	cnfa->stflags = (char *) MALLOC(nstates * sizeof(char));
+	cnfa->states = (struct carc **) MALLOC(nstates * sizeof(struct carc *));
+	cnfa->arcs = (struct carc *) MALLOC(narcs * sizeof(struct carc));
+	if (cnfa->stflags == NULL || cnfa->states == NULL || cnfa->arcs == NULL)
+	{
+		if (cnfa->stflags != NULL)
+			FREE(cnfa->stflags);
+		if (cnfa->states != NULL)
+			FREE(cnfa->states);
+		if (cnfa->arcs != NULL)
+			FREE(cnfa->arcs);
+		NERR(REG_ESPACE);
+		return;
+	}
+	cnfa->nstates = nstates;
+	cnfa->pre = nfa->pre->no;
+	cnfa->post = nfa->post->no;
+	cnfa->bos[0] = nfa->bos[0];
+	cnfa->bos[1] = nfa->bos[1];
+	cnfa->eos[0] = nfa->eos[0];
+	cnfa->eos[1] = nfa->eos[1];
+	cnfa->ncolors = maxcolor(nfa->cm) + 1;
+	cnfa->flags = nfa->flags;
+	cnfa->minmatchall = nfa->minmatchall;
+	cnfa->maxmatchall = nfa->maxmatchall;
+
+	ca = cnfa->arcs;
+	for (s = nfa->states; s != NULL; s = s->next)
+	{
+		assert((size_t) s->no < nstates);
+		cnfa->stflags[s->no] = 0;
+		cnfa->states[s->no] = ca;
+		first = ca;
+		for (a = s->outs; a != NULL; a = a->outchain)
+			switch (a->type)
+			{
+				case PLAIN:
+					ca->co = a->co;
+					ca->to = a->to->no;
+					ca++;
+					break;
+				case LACON:
+					assert(s->no != cnfa->pre);
+					assert(a->co >= 0);
+					ca->co = (color) (cnfa->ncolors + a->co);
+					ca->to = a->to->no;
+					ca++;
+					cnfa->flags |= HASLACONS;
+					break;
+				default:
+					NERR(REG_ASSERT);
+					return;
+			}
+		carcsort(first, ca - first);
+		ca->co = COLORLESS;
+		ca->to = 0;
+		ca++;
+	}
+	assert(ca == &cnfa->arcs[narcs]);
+	assert(cnfa->nstates != 0);
+
+	/* mark no-progress states */
+	for (a = nfa->pre->outs; a != NULL; a = a->outchain)
+		cnfa->stflags[a->to->no] = CNFA_NOPROGRESS;
+	cnfa->stflags[nfa->pre->no] = CNFA_NOPROGRESS;
+}
+
+/*
+ * carcsort - sort compacted-NFA arcs by color
+ */
+static void
+carcsort(struct carc *first, size_t n)
+{
+	if (n > 1)
+		qsort(first, n, sizeof(struct carc), carc_cmp);
+}
+
+static int
+carc_cmp(const void *a, const void *b)
+{
+	const struct carc *aa = (const struct carc *) a;
+	const struct carc *bb = (const struct carc *) b;
+
+	if (aa->co < bb->co)
+		return -1;
+	if (aa->co > bb->co)
+		return +1;
+	if (aa->to < bb->to)
+		return -1;
+	if (aa->to > bb->to)
+		return +1;
+	return 0;
+}
+
+/*
+ * freecnfa - free a compacted NFA
+ */
+static void
+freecnfa(struct cnfa *cnfa)
+{
+	assert(!NULLCNFA(*cnfa));	/* not empty already */
+	FREE(cnfa->stflags);
+	FREE(cnfa->states);
+	FREE(cnfa->arcs);
+	ZAPCNFA(*cnfa);
+}
+
+/*
+ * dumpnfa - dump an NFA in human-readable form
+ */
+static void
+dumpnfa(struct nfa *nfa,
+		FILE *f)
+{
+#ifdef REG_DEBUG
+	struct state *s;
+	int			nstates = 0;
+	int			narcs = 0;
+
+	fprintf(f, "pre %d, post %d", nfa->pre->no, nfa->post->no);
+	if (nfa->bos[0] != COLORLESS)
+		fprintf(f, ", bos [%ld]", (long) nfa->bos[0]);
+	if (nfa->bos[1] != COLORLESS)
+		fprintf(f, ", bol [%ld]", (long) nfa->bos[1]);
+	if (nfa->eos[0] != COLORLESS)
+		fprintf(f, ", eos [%ld]", (long) nfa->eos[0]);
+	if (nfa->eos[1] != COLORLESS)
+		fprintf(f, ", eol [%ld]", (long) nfa->eos[1]);
+	if (nfa->flags & HASLACONS)
+		fprintf(f, ", haslacons");
+	if (nfa->flags & MATCHALL)
+	{
+		fprintf(f, ", minmatchall %d", nfa->minmatchall);
+		if (nfa->maxmatchall == DUPINF)
+			fprintf(f, ", maxmatchall inf");
+		else
+			fprintf(f, ", maxmatchall %d", nfa->maxmatchall);
+	}
+	fprintf(f, "\n");
+	for (s = nfa->states; s != NULL; s = s->next)
+	{
+		dumpstate(s, f);
+		nstates++;
+		narcs += s->nouts;
+	}
+	fprintf(f, "total of %d states, %d arcs\n", nstates, narcs);
+	if (nfa->parent == NULL)
+		dumpcolors(nfa->cm, f);
+	fflush(f);
+#endif
+}
+
+#ifdef REG_DEBUG				/* subordinates of dumpnfa */
+
+/*
+ * dumpstate - dump an NFA state in human-readable form
+ */
+static void
+dumpstate(struct state *s,
+		  FILE *f)
+{
+	struct arc *a;
+
+	fprintf(f, "%d%s%c", s->no, (s->tmp != NULL) ? "T" : "",
+			(s->flag) ? s->flag : '.');
+	if (s->prev != NULL && s->prev->next != s)
+		fprintf(f, "\tstate chain bad\n");
+	if (s->nouts == 0)
+		fprintf(f, "\tno out arcs\n");
+	else
+		dumparcs(s, f);
+	for (a = s->ins; a != NULL; a = a->inchain)
+	{
+		if (a->to != s)
+			fprintf(f, "\tlink from %d to %d on %d's in-chain\n",
+					a->from->no, a->to->no, s->no);
+	}
+	fflush(f);
+}
+
+/*
+ * dumparcs - dump out-arcs in human-readable form
+ */
+static void
+dumparcs(struct state *s,
+		 FILE *f)
+{
+	int			pos;
+	struct arc *a;
+
+	/* printing oldest arcs first is usually clearer */
+	a = s->outs;
+	assert(a != NULL);
+	while (a->outchain != NULL)
+		a = a->outchain;
+	pos = 1;
+	do
+	{
+		dumparc(a, s, f);
+		if (pos == 5)
+		{
+			fprintf(f, "\n");
+			pos = 1;
+		}
+		else
+			pos++;
+		a = a->outchainRev;
+	} while (a != NULL);
+	if (pos != 1)
+		fprintf(f, "\n");
+}
+
+/*
+ * dumparc - dump one outarc in readable form, including prefixing tab
+ */
+static void
+dumparc(struct arc *a,
+		struct state *s,
+		FILE *f)
+{
+	struct arc *aa;
+
+	fprintf(f, "\t");
+	switch (a->type)
+	{
+		case PLAIN:
+			if (a->co == RAINBOW)
+				fprintf(f, "[*]");
+			else
+				fprintf(f, "[%ld]", (long) a->co);
+			break;
+		case AHEAD:
+			if (a->co == RAINBOW)
+				fprintf(f, ">*>");
+			else
+				fprintf(f, ">%ld>", (long) a->co);
+			break;
+		case BEHIND:
+			if (a->co == RAINBOW)
+				fprintf(f, "<*<");
+			else
+				fprintf(f, "<%ld<", (long) a->co);
+			break;
+		case LACON:
+			fprintf(f, ":%ld:", (long) a->co);
+			break;
+		case '^':
+		case '$':
+			fprintf(f, "%c%d", a->type, (int) a->co);
+			break;
+		case EMPTY:
+			break;
+		default:
+			fprintf(f, "0x%x/0%lo", a->type, (long) a->co);
+			break;
+	}
+	if (a->from != s)
+		fprintf(f, "?%d?", a->from->no);
+	for (aa = a->from->outs; aa != NULL; aa = aa->outchain)
+		if (aa == a)
+			break;				/* NOTE BREAK OUT */
+	if (aa == NULL)
+		fprintf(f, "?!?");		/* missing from out-chain */
+	fprintf(f, "->");
+	if (a->to == NULL)
+	{
+		fprintf(f, "NULL");
+		return;
+	}
+	fprintf(f, "%d", a->to->no);
+	for (aa = a->to->ins; aa != NULL; aa = aa->inchain)
+		if (aa == a)
+			break;				/* NOTE BREAK OUT */
+	if (aa == NULL)
+		fprintf(f, "?!?");		/* missing from in-chain */
+}
+#endif							/* REG_DEBUG */
+
+/*
+ * dumpcnfa - dump a compacted NFA in human-readable form
+ */
+#ifdef REG_DEBUG
+static void
+dumpcnfa(struct cnfa *cnfa,
+		 FILE *f)
+{
+	int			st;
+
+	fprintf(f, "pre %d, post %d", cnfa->pre, cnfa->post);
+	if (cnfa->bos[0] != COLORLESS)
+		fprintf(f, ", bos [%ld]", (long) cnfa->bos[0]);
+	if (cnfa->bos[1] != COLORLESS)
+		fprintf(f, ", bol [%ld]", (long) cnfa->bos[1]);
+	if (cnfa->eos[0] != COLORLESS)
+		fprintf(f, ", eos [%ld]", (long) cnfa->eos[0]);
+	if (cnfa->eos[1] != COLORLESS)
+		fprintf(f, ", eol [%ld]", (long) cnfa->eos[1]);
+	if (cnfa->flags & HASLACONS)
+		fprintf(f, ", haslacons");
+	if (cnfa->flags & MATCHALL)
+	{
+		fprintf(f, ", minmatchall %d", cnfa->minmatchall);
+		if (cnfa->maxmatchall == DUPINF)
+			fprintf(f, ", maxmatchall inf");
+		else
+			fprintf(f, ", maxmatchall %d", cnfa->maxmatchall);
+	}
+	fprintf(f, "\n");
+	for (st = 0; st < cnfa->nstates; st++)
+		dumpcstate(st, cnfa, f);
+	fflush(f);
+}
+#endif
+
+#ifdef REG_DEBUG				/* subordinates of dumpcnfa */
+
+/*
+ * dumpcstate - dump a compacted-NFA state in human-readable form
+ */
+static void
+dumpcstate(int st,
+		   struct cnfa *cnfa,
+		   FILE *f)
+{
+	struct carc *ca;
+	int			pos;
+
+	fprintf(f, "%d%s", st, (cnfa->stflags[st] & CNFA_NOPROGRESS) ? ":" : ".");
+	pos = 1;
+	for (ca = cnfa->states[st]; ca->co != COLORLESS; ca++)
+	{
+		if (ca->co == RAINBOW)
+			fprintf(f, "\t[*]->%d", ca->to);
+		else if (ca->co < cnfa->ncolors)
+			fprintf(f, "\t[%ld]->%d", (long) ca->co, ca->to);
+		else
+			fprintf(f, "\t:%ld:->%d", (long) (ca->co - cnfa->ncolors), ca->to);
+		if (pos == 5)
+		{
+			fprintf(f, "\n");
+			pos = 1;
+		}
+		else
+			pos++;
+	}
+	if (ca == cnfa->states[st] || pos != 1)
+		fprintf(f, "\n");
+	fflush(f);
+}
+
+#endif							/* REG_DEBUG */