1 files changed, 1701 insertions, 0 deletions

diff --git a/contrib/llvm-project/llvm/lib/Support/regcomp.c b/contrib/llvm-project/llvm/lib/Support/regcomp.c
new file mode 100644
index 000000000000..12669ab75d1a
--- /dev/null
+++ b/contrib/llvm-project/llvm/lib/Support/regcomp.c
@@ -0,0 +1,1701 @@
+/*-
+ * This code is derived from OpenBSD's libc/regex, original license follows:
+ *
+ * Copyright (c) 1992, 1993, 1994 Henry Spencer.
+ * Copyright (c) 1992, 1993, 1994
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Henry Spencer.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 THE REGENTS OR CONTRIBUTORS 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.
+ *
+ *	@(#)regcomp.c	8.5 (Berkeley) 3/20/94
+ */
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <limits.h>
+#include <stdlib.h>
+#include "regex_impl.h"
+
+#include "regutils.h"
+#include "regex2.h"
+
+#include "llvm/Config/config.h"
+
+/* character-class table */
+static struct cclass {
+	const char *name;
+	const char *chars;
+	const char *multis;
+} cclasses[] = {
+	{ "alnum",	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz\
+0123456789",				""} ,
+	{ "alpha",	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz",
+					""} ,
+	{ "blank",	" \t",		""} ,
+	{ "cntrl",	"\007\b\t\n\v\f\r\1\2\3\4\5\6\16\17\20\21\22\23\24\
+\25\26\27\30\31\32\33\34\35\36\37\177",	""} ,
+	{ "digit",	"0123456789",	""} ,
+	{ "graph",	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz\
+0123456789!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
+					""} ,
+	{ "lower",	"abcdefghijklmnopqrstuvwxyz",
+					""} ,
+	{ "print",	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz\
+0123456789!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~ ",
+					""} ,
+	{ "punct",	"!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
+					""} ,
+	{ "space",	"\t\n\v\f\r ",	""} ,
+	{ "upper",	"ABCDEFGHIJKLMNOPQRSTUVWXYZ",
+					""} ,
+	{ "xdigit",	"0123456789ABCDEFabcdef",
+					""} ,
+	{ NULL,		0,		"" }
+};
+
+/* character-name table */
+static struct cname {
+	const char *name;
+	char code;
+} cnames[] = {
+	{ "NUL",			'\0' },
+	{ "SOH",			'\001' },
+	{ "STX",			'\002' },
+	{ "ETX",			'\003' },
+	{ "EOT",			'\004' },
+	{ "ENQ",			'\005' },
+	{ "ACK",			'\006' },
+	{ "BEL",			'\007' },
+	{ "alert",			'\007' },
+	{ "BS",				'\010' },
+	{ "backspace",			'\b' },
+	{ "HT",				'\011' },
+	{ "tab",			'\t' },
+	{ "LF",				'\012' },
+	{ "newline",			'\n' },
+	{ "VT",				'\013' },
+	{ "vertical-tab",		'\v' },
+	{ "FF",				'\014' },
+	{ "form-feed",			'\f' },
+	{ "CR",				'\015' },
+	{ "carriage-return",		'\r' },
+	{ "SO",				'\016' },
+	{ "SI",				'\017' },
+	{ "DLE",			'\020' },
+	{ "DC1",			'\021' },
+	{ "DC2",			'\022' },
+	{ "DC3",			'\023' },
+	{ "DC4",			'\024' },
+	{ "NAK",			'\025' },
+	{ "SYN",			'\026' },
+	{ "ETB",			'\027' },
+	{ "CAN",			'\030' },
+	{ "EM",				'\031' },
+	{ "SUB",			'\032' },
+	{ "ESC",			'\033' },
+	{ "IS4",			'\034' },
+	{ "FS",				'\034' },
+	{ "IS3",			'\035' },
+	{ "GS",				'\035' },
+	{ "IS2",			'\036' },
+	{ "RS",				'\036' },
+	{ "IS1",			'\037' },
+	{ "US",				'\037' },
+	{ "space",			' ' },
+	{ "exclamation-mark",		'!' },
+	{ "quotation-mark",		'"' },
+	{ "number-sign",		'#' },
+	{ "dollar-sign",		'$' },
+	{ "percent-sign",		'%' },
+	{ "ampersand",			'&' },
+	{ "apostrophe",			'\'' },
+	{ "left-parenthesis",		'(' },
+	{ "right-parenthesis",		')' },
+	{ "asterisk",			'*' },
+	{ "plus-sign",			'+' },
+	{ "comma",			',' },
+	{ "hyphen",			'-' },
+	{ "hyphen-minus",		'-' },
+	{ "period",			'.' },
+	{ "full-stop",			'.' },
+	{ "slash",			'/' },
+	{ "solidus",			'/' },
+	{ "zero",			'0' },
+	{ "one",			'1' },
+	{ "two",			'2' },
+	{ "three",			'3' },
+	{ "four",			'4' },
+	{ "five",			'5' },
+	{ "six",			'6' },
+	{ "seven",			'7' },
+	{ "eight",			'8' },
+	{ "nine",			'9' },
+	{ "colon",			':' },
+	{ "semicolon",			';' },
+	{ "less-than-sign",		'<' },
+	{ "equals-sign",		'=' },
+	{ "greater-than-sign",		'>' },
+	{ "question-mark",		'?' },
+	{ "commercial-at",		'@' },
+	{ "left-square-bracket",	'[' },
+	{ "backslash",			'\\' },
+	{ "reverse-solidus",		'\\' },
+	{ "right-square-bracket",	']' },
+	{ "circumflex",			'^' },
+	{ "circumflex-accent",		'^' },
+	{ "underscore",			'_' },
+	{ "low-line",			'_' },
+	{ "grave-accent",		'`' },
+	{ "left-brace",			'{' },
+	{ "left-curly-bracket",		'{' },
+	{ "vertical-line",		'|' },
+	{ "right-brace",		'}' },
+	{ "right-curly-bracket",	'}' },
+	{ "tilde",			'~' },
+	{ "DEL",			'\177' },
+	{ NULL,				0 }
+};
+
+/*
+ * parse structure, passed up and down to avoid global variables and
+ * other clumsinesses
+ */
+struct parse {
+	char *next;		/* next character in RE */
+	char *end;		/* end of string (-> NUL normally) */
+	int error;		/* has an error been seen? */
+	sop *strip;		/* malloced strip */
+	sopno ssize;		/* malloced strip size (allocated) */
+	sopno slen;		/* malloced strip length (used) */
+	int ncsalloc;		/* number of csets allocated */
+	struct re_guts *g;
+#	define	NPAREN	10	/* we need to remember () 1-9 for back refs */
+	sopno pbegin[NPAREN];	/* -> ( ([0] unused) */
+	sopno pend[NPAREN];	/* -> ) ([0] unused) */
+};
+
+static void p_ere(struct parse *, int);
+static void p_ere_exp(struct parse *);
+static void p_str(struct parse *);
+static void p_bre(struct parse *, int, int);
+static int p_simp_re(struct parse *, int);
+static int p_count(struct parse *);
+static void p_bracket(struct parse *);
+static void p_b_term(struct parse *, cset *);
+static void p_b_cclass(struct parse *, cset *);
+static void p_b_eclass(struct parse *, cset *);
+static char p_b_symbol(struct parse *);
+static char p_b_coll_elem(struct parse *, int);
+static char othercase(int);
+static void bothcases(struct parse *, int);
+static void ordinary(struct parse *, int);
+static void nonnewline(struct parse *);
+static void repeat(struct parse *, sopno, int, int);
+static int seterr(struct parse *, int);
+static cset *allocset(struct parse *);
+static void freeset(struct parse *, cset *);
+static int freezeset(struct parse *, cset *);
+static int firstch(struct parse *, cset *);
+static int nch(struct parse *, cset *);
+static void mcadd(struct parse *, cset *, const char *);
+static void mcinvert(struct parse *, cset *);
+static void mccase(struct parse *, cset *);
+static int isinsets(struct re_guts *, int);
+static int samesets(struct re_guts *, int, int);
+static void categorize(struct parse *, struct re_guts *);
+static sopno dupl(struct parse *, sopno, sopno);
+static void doemit(struct parse *, sop, size_t);
+static void doinsert(struct parse *, sop, size_t, sopno);
+static void dofwd(struct parse *, sopno, sop);
+static void enlarge(struct parse *, sopno);
+static void stripsnug(struct parse *, struct re_guts *);
+static void findmust(struct parse *, struct re_guts *);
+static sopno pluscount(struct parse *, struct re_guts *);
+
+static char nuls[10];		/* place to point scanner in event of error */
+
+/*
+ * macros for use with parse structure
+ * BEWARE:  these know that the parse structure is named `p' !!!
+ */
+#define	PEEK()	(*p->next)
+#define	PEEK2()	(*(p->next+1))
+#define	MORE()	(p->next < p->end)
+#define	MORE2()	(p->next+1 < p->end)
+#define	SEE(c)	(MORE() && PEEK() == (c))
+#define	SEETWO(a, b)	(MORE() && MORE2() && PEEK() == (a) && PEEK2() == (b))
+#define	EAT(c)	((SEE(c)) ? (NEXT(), 1) : 0)
+#define	EATTWO(a, b)	((SEETWO(a, b)) ? (NEXT2(), 1) : 0)
+#define	NEXT()	(p->next++)
+#define	NEXT2()	(p->next += 2)
+#define	NEXTn(n)	(p->next += (n))
+#define	GETNEXT()	(*p->next++)
+#define	SETERROR(e)	seterr(p, (e))
+#define	REQUIRE(co, e)	(void)((co) || SETERROR(e))
+#define	MUSTSEE(c, e)	(REQUIRE(MORE() && PEEK() == (c), e))
+#define	MUSTEAT(c, e)	(REQUIRE(MORE() && GETNEXT() == (c), e))
+#define	MUSTNOTSEE(c, e)	(REQUIRE(!MORE() || PEEK() != (c), e))
+#define	EMIT(op, sopnd)	doemit(p, (sop)(op), (size_t)(sopnd))
+#define	INSERT(op, pos)	doinsert(p, (sop)(op), HERE()-(pos)+1, pos)
+#define	AHEAD(pos)		dofwd(p, pos, HERE()-(pos))
+#define	ASTERN(sop, pos)	EMIT(sop, HERE()-pos)
+#define	HERE()		(p->slen)
+#define	THERE()		(p->slen - 1)
+#define	THERETHERE()	(p->slen - 2)
+#define	DROP(n)	(p->slen -= (n))
+
+#ifdef	_POSIX2_RE_DUP_MAX
+#define	DUPMAX	_POSIX2_RE_DUP_MAX
+#else
+#define	DUPMAX	255
+#endif
+#define	INFINITY	(DUPMAX + 1)
+
+#ifndef NDEBUG
+static int never = 0;		/* for use in asserts; shuts lint up */
+#else
+#define	never	0		/* some <assert.h>s have bugs too */
+#endif
+
+/*
+ - llvm_regcomp - interface for parser and compilation
+ */
+int				/* 0 success, otherwise REG_something */
+llvm_regcomp(llvm_regex_t *preg, const char *pattern, int cflags)
+{
+	struct parse pa;
+	struct re_guts *g;
+	struct parse *p = &pa;
+	int i;
+	size_t len;
+#ifdef REDEBUG
+#	define	GOODFLAGS(f)	(f)
+#else
+#	define	GOODFLAGS(f)	((f)&~REG_DUMP)
+#endif
+
+	cflags = GOODFLAGS(cflags);
+	if ((cflags&REG_EXTENDED) && (cflags&REG_NOSPEC))
+		return(REG_INVARG);
+
+	if (cflags&REG_PEND) {
+		if (preg->re_endp < pattern)
+			return(REG_INVARG);
+		len = preg->re_endp - pattern;
+	} else
+		len = strlen((const char *)pattern);
+
+	/* do the mallocs early so failure handling is easy */
+	g = (struct re_guts *)malloc(sizeof(struct re_guts) +
+							(NC-1)*sizeof(cat_t));
+	if (g == NULL)
+		return(REG_ESPACE);
+	p->ssize = len/(size_t)2*(size_t)3 + (size_t)1;	/* ugh */
+	p->strip = (sop *)calloc(p->ssize, sizeof(sop));
+	p->slen = 0;
+	if (p->strip == NULL) {
+		free((char *)g);
+		return(REG_ESPACE);
+	}
+
+	/* set things up */
+	p->g = g;
+	p->next = (char *)pattern;	/* convenience; we do not modify it */
+	p->end = p->next + len;
+	p->error = 0;
+	p->ncsalloc = 0;
+	for (i = 0; i < NPAREN; i++) {
+		p->pbegin[i] = 0;
+		p->pend[i] = 0;
+	}
+	g->csetsize = NC;
+	g->sets = NULL;
+	g->setbits = NULL;
+	g->ncsets = 0;
+	g->cflags = cflags;
+	g->iflags = 0;
+	g->nbol = 0;
+	g->neol = 0;
+	g->must = NULL;
+	g->mlen = 0;
+	g->nsub = 0;
+	g->ncategories = 1;	/* category 0 is "everything else" */
+	g->categories = &g->catspace[-(CHAR_MIN)];
+	(void) memset((char *)g->catspace, 0, NC*sizeof(cat_t));
+	g->backrefs = 0;
+
+	/* do it */
+	EMIT(OEND, 0);
+	g->firststate = THERE();
+	if (cflags&REG_EXTENDED)
+		p_ere(p, OUT);
+	else if (cflags&REG_NOSPEC)
+		p_str(p);
+	else
+		p_bre(p, OUT, OUT);
+	EMIT(OEND, 0);
+	g->laststate = THERE();
+
+	/* tidy up loose ends and fill things in */
+	categorize(p, g);
+	stripsnug(p, g);
+	findmust(p, g);
+	g->nplus = pluscount(p, g);
+	g->magic = MAGIC2;
+	preg->re_nsub = g->nsub;
+	preg->re_g = g;
+	preg->re_magic = MAGIC1;
+#ifndef REDEBUG
+	/* not debugging, so can't rely on the assert() in llvm_regexec() */
+	if (g->iflags&REGEX_BAD)
+		SETERROR(REG_ASSERT);
+#endif
+
+	/* win or lose, we're done */
+	if (p->error != 0)	/* lose */
+		llvm_regfree(preg);
+	return(p->error);
+}
+
+/*
+ - p_ere - ERE parser top level, concatenation and alternation
+ */
+static void
+p_ere(struct parse *p, int stop)	/* character this ERE should end at */
+{
+	char c;
+	sopno prevback = 0;
+	sopno prevfwd = 0;
+	sopno conc;
+	int first = 1;		/* is this the first alternative? */
+
+	for (;;) {
+		/* do a bunch of concatenated expressions */
+		conc = HERE();
+		while (MORE() && (c = PEEK()) != '|' && c != stop)
+			p_ere_exp(p);
+		REQUIRE(HERE() != conc, REG_EMPTY);	/* require nonempty */
+
+		if (!EAT('|'))
+			break;		/* NOTE BREAK OUT */
+
+		if (first) {
+			INSERT(OCH_, conc);	/* offset is wrong */
+			prevfwd = conc;
+			prevback = conc;
+			first = 0;
+		}
+		ASTERN(OOR1, prevback);
+		prevback = THERE();
+		AHEAD(prevfwd);			/* fix previous offset */
+		prevfwd = HERE();
+		EMIT(OOR2, 0);			/* offset is very wrong */
+	}
+
+	if (!first) {		/* tail-end fixups */
+		AHEAD(prevfwd);
+		ASTERN(O_CH, prevback);
+	}
+
+	assert(!MORE() || SEE(stop));
+}
+
+/*
+ - p_ere_exp - parse one subERE, an atom possibly followed by a repetition op
+ */
+static void
+p_ere_exp(struct parse *p)
+{
+	char c;
+	sopno pos;
+	int count;
+	int count2;
+	int backrefnum;
+	sopno subno;
+	int wascaret = 0;
+
+	assert(MORE());		/* caller should have ensured this */
+	c = GETNEXT();
+
+	pos = HERE();
+	switch (c) {
+	case '(':
+		REQUIRE(MORE(), REG_EPAREN);
+		p->g->nsub++;
+		subno = p->g->nsub;
+		if (subno < NPAREN)
+			p->pbegin[subno] = HERE();
+		EMIT(OLPAREN, subno);
+		if (!SEE(')'))
+			p_ere(p, ')');
+		if (subno < NPAREN) {
+			p->pend[subno] = HERE();
+			assert(p->pend[subno] != 0);
+		}
+		EMIT(ORPAREN, subno);
+		MUSTEAT(')', REG_EPAREN);
+		break;
+#ifndef POSIX_MISTAKE
+	case ')':		/* happens only if no current unmatched ( */
+		/*
+		 * You may ask, why the ifndef?  Because I didn't notice
+		 * this until slightly too late for 1003.2, and none of the
+		 * other 1003.2 regular-expression reviewers noticed it at
+		 * all.  So an unmatched ) is legal POSIX, at least until
+		 * we can get it fixed.
+		 */
+		SETERROR(REG_EPAREN);
+		break;
+#endif
+	case '^':
+		EMIT(OBOL, 0);
+		p->g->iflags |= USEBOL;
+		p->g->nbol++;
+		wascaret = 1;
+		break;
+	case '$':
+		EMIT(OEOL, 0);
+		p->g->iflags |= USEEOL;
+		p->g->neol++;
+		break;
+	case '|':
+		SETERROR(REG_EMPTY);
+		break;
+	case '*':
+	case '+':
+	case '?':
+		SETERROR(REG_BADRPT);
+		break;
+	case '.':
+		if (p->g->cflags&REG_NEWLINE)
+			nonnewline(p);
+		else
+			EMIT(OANY, 0);
+		break;
+	case '[':
+		p_bracket(p);
+		break;
+	case '\\':
+		REQUIRE(MORE(), REG_EESCAPE);
+		c = GETNEXT();
+		if (c >= '1' && c <= '9') {
+			/* \[0-9] is taken to be a back-reference to a previously specified
+			 * matching group. backrefnum will hold the number. The matching
+			 * group must exist (i.e. if \4 is found there must have been at
+			 * least 4 matching groups specified in the pattern previously).
+			 */
+			backrefnum = c - '0';
+			if (p->pend[backrefnum] == 0) {
+				SETERROR(REG_ESUBREG);
+				break;
+			}
+
+			/* Make sure everything checks out and emit the sequence
+			 * that marks a back-reference to the parse structure.
+			 */
+			assert(backrefnum <= p->g->nsub);
+			EMIT(OBACK_, backrefnum);
+			assert(p->pbegin[backrefnum] != 0);
+			assert(OP(p->strip[p->pbegin[backrefnum]]) != OLPAREN);
+			assert(OP(p->strip[p->pend[backrefnum]]) != ORPAREN);
+			(void) dupl(p, p->pbegin[backrefnum]+1, p->pend[backrefnum]);
+			EMIT(O_BACK, backrefnum);
+			p->g->backrefs = 1;
+		} else {
+			/* Other chars are simply themselves when escaped with a backslash.
+			 */
+			ordinary(p, c);
+		}
+		break;
+	case '{':		/* okay as ordinary except if digit follows */
+		REQUIRE(!MORE() || !isdigit((uch)PEEK()), REG_BADRPT);
+		/* FALLTHROUGH */
+	default:
+		ordinary(p, c);
+		break;
+	}
+
+	if (!MORE())
+		return;
+	c = PEEK();
+	/* we call { a repetition if followed by a digit */
+	if (!( c == '*' || c == '+' || c == '?' ||
+				(c == '{' && MORE2() && isdigit((uch)PEEK2())) ))
+		return;		/* no repetition, we're done */
+	NEXT();
+
+	REQUIRE(!wascaret, REG_BADRPT);
+	switch (c) {
+	case '*':	/* implemented as +? */
+		/* this case does not require the (y|) trick, noKLUDGE */
+		INSERT(OPLUS_, pos);
+		ASTERN(O_PLUS, pos);
+		INSERT(OQUEST_, pos);
+		ASTERN(O_QUEST, pos);
+		break;
+	case '+':
+		INSERT(OPLUS_, pos);
+		ASTERN(O_PLUS, pos);
+		break;
+	case '?':
+		/* KLUDGE: emit y? as (y|) until subtle bug gets fixed */
+		INSERT(OCH_, pos);		/* offset slightly wrong */
+		ASTERN(OOR1, pos);		/* this one's right */
+		AHEAD(pos);			/* fix the OCH_ */
+		EMIT(OOR2, 0);			/* offset very wrong... */
+		AHEAD(THERE());			/* ...so fix it */
+		ASTERN(O_CH, THERETHERE());
+		break;
+	case '{':
+		count = p_count(p);
+		if (EAT(',')) {
+			if (isdigit((uch)PEEK())) {
+				count2 = p_count(p);
+				REQUIRE(count <= count2, REG_BADBR);
+			} else		/* single number with comma */
+				count2 = INFINITY;
+		} else		/* just a single number */
+			count2 = count;
+		repeat(p, pos, count, count2);
+		if (!EAT('}')) {	/* error heuristics */
+			while (MORE() && PEEK() != '}')
+				NEXT();
+			REQUIRE(MORE(), REG_EBRACE);
+			SETERROR(REG_BADBR);
+		}
+		break;
+	}
+
+	if (!MORE())
+		return;
+	c = PEEK();
+	if (!( c == '*' || c == '+' || c == '?' ||
+				(c == '{' && MORE2() && isdigit((uch)PEEK2())) ) )
+		return;
+	SETERROR(REG_BADRPT);
+}
+
+/*
+ - p_str - string (no metacharacters) "parser"
+ */
+static void
+p_str(struct parse *p)
+{
+	REQUIRE(MORE(), REG_EMPTY);
+	while (MORE())
+		ordinary(p, GETNEXT());
+}
+
+/*
+ - p_bre - BRE parser top level, anchoring and concatenation
+ * Giving end1 as OUT essentially eliminates the end1/end2 check.
+ *
+ * This implementation is a bit of a kludge, in that a trailing $ is first
+ * taken as an ordinary character and then revised to be an anchor.  The
+ * only undesirable side effect is that '$' gets included as a character
+ * category in such cases.  This is fairly harmless; not worth fixing.
+ * The amount of lookahead needed to avoid this kludge is excessive.
+ */
+static void
+p_bre(struct parse *p,
+    int end1,		/* first terminating character */
+    int end2)		/* second terminating character */
+{
+	sopno start = HERE();
+	int first = 1;			/* first subexpression? */
+	int wasdollar = 0;
+
+	if (EAT('^')) {
+		EMIT(OBOL, 0);
+		p->g->iflags |= USEBOL;
+		p->g->nbol++;
+	}
+	while (MORE() && !SEETWO(end1, end2)) {
+		wasdollar = p_simp_re(p, first);
+		first = 0;
+	}
+	if (wasdollar) {	/* oops, that was a trailing anchor */
+		DROP(1);
+		EMIT(OEOL, 0);
+		p->g->iflags |= USEEOL;
+		p->g->neol++;
+	}
+
+	REQUIRE(HERE() != start, REG_EMPTY);	/* require nonempty */
+}
+
+/*
+ - p_simp_re - parse a simple RE, an atom possibly followed by a repetition
+ */
+static int			/* was the simple RE an unbackslashed $? */
+p_simp_re(struct parse *p,
+    int starordinary)		/* is a leading * an ordinary character? */
+{
+	int c;
+	int count;
+	int count2;
+	sopno pos;
+	int i;
+	sopno subno;
+#	define	BACKSL	(1<<CHAR_BIT)
+
+        pos = HERE(); /* repetition op, if any, covers from here */
+
+        assert(MORE()); /* caller should have ensured this */
+        c = GETNEXT();
+	if (c == '\\') {
+		REQUIRE(MORE(), REG_EESCAPE);
+		c = BACKSL | GETNEXT();
+	}
+	switch (c) {
+	case '.':
+		if (p->g->cflags&REG_NEWLINE)
+			nonnewline(p);
+		else
+			EMIT(OANY, 0);
+		break;
+	case '[':
+		p_bracket(p);
+		break;
+	case BACKSL|'{':
+		SETERROR(REG_BADRPT);
+		break;
+	case BACKSL|'(':
+		p->g->nsub++;
+		subno = p->g->nsub;
+		if (subno < NPAREN)
+			p->pbegin[subno] = HERE();
+		EMIT(OLPAREN, subno);
+		/* the MORE here is an error heuristic */
+		if (MORE() && !SEETWO('\\', ')'))
+			p_bre(p, '\\', ')');
+		if (subno < NPAREN) {
+			p->pend[subno] = HERE();
+			assert(p->pend[subno] != 0);
+		}
+		EMIT(ORPAREN, subno);
+		REQUIRE(EATTWO('\\', ')'), REG_EPAREN);
+		break;
+	case BACKSL|')':	/* should not get here -- must be user */
+	case BACKSL|'}':
+		SETERROR(REG_EPAREN);
+		break;
+	case BACKSL|'1':
+	case BACKSL|'2':
+	case BACKSL|'3':
+	case BACKSL|'4':
+	case BACKSL|'5':
+	case BACKSL|'6':
+	case BACKSL|'7':
+	case BACKSL|'8':
+	case BACKSL|'9':
+		i = (c&~BACKSL) - '0';
+		assert(i < NPAREN);
+		if (p->pend[i] != 0) {
+			assert(i <= p->g->nsub);
+			EMIT(OBACK_, i);
+			assert(p->pbegin[i] != 0);
+			assert(OP(p->strip[p->pbegin[i]]) == OLPAREN);
+			assert(OP(p->strip[p->pend[i]]) == ORPAREN);
+			(void) dupl(p, p->pbegin[i]+1, p->pend[i]);
+			EMIT(O_BACK, i);
+		} else
+			SETERROR(REG_ESUBREG);
+		p->g->backrefs = 1;
+		break;
+	case '*':
+		REQUIRE(starordinary, REG_BADRPT);
+		/* FALLTHROUGH */
+	default:
+		ordinary(p, (char)c);
+		break;
+	}
+
+	if (EAT('*')) {		/* implemented as +? */
+		/* this case does not require the (y|) trick, noKLUDGE */
+		INSERT(OPLUS_, pos);
+		ASTERN(O_PLUS, pos);
+		INSERT(OQUEST_, pos);
+		ASTERN(O_QUEST, pos);
+	} else if (EATTWO('\\', '{')) {
+		count = p_count(p);
+		if (EAT(',')) {
+			if (MORE() && isdigit((uch)PEEK())) {
+				count2 = p_count(p);
+				REQUIRE(count <= count2, REG_BADBR);
+			} else		/* single number with comma */
+				count2 = INFINITY;
+		} else		/* just a single number */
+			count2 = count;
+		repeat(p, pos, count, count2);
+		if (!EATTWO('\\', '}')) {	/* error heuristics */
+			while (MORE() && !SEETWO('\\', '}'))
+				NEXT();
+			REQUIRE(MORE(), REG_EBRACE);
+			SETERROR(REG_BADBR);
+		}
+	} else if (c == '$')	/* $ (but not \$) ends it */
+		return(1);
+
+	return(0);
+}
+
+/*
+ - p_count - parse a repetition count
+ */
+static int			/* the value */
+p_count(struct parse *p)
+{
+	int count = 0;
+	int ndigits = 0;
+
+	while (MORE() && isdigit((uch)PEEK()) && count <= DUPMAX) {
+		count = count*10 + (GETNEXT() - '0');
+		ndigits++;
+	}
+
+	REQUIRE(ndigits > 0 && count <= DUPMAX, REG_BADBR);
+	return(count);
+}
+
+/*
+ - p_bracket - parse a bracketed character list
+ *
+ * Note a significant property of this code:  if the allocset() did SETERROR,
+ * no set operations are done.
+ */
+static void
+p_bracket(struct parse *p)
+{
+	cset *cs;
+	int invert = 0;
+
+	/* Dept of Truly Sickening Special-Case Kludges */
+	if (p->next + 5 < p->end && strncmp(p->next, "[:<:]]", 6) == 0) {
+		EMIT(OBOW, 0);
+		NEXTn(6);
+		return;
+	}
+	if (p->next + 5 < p->end && strncmp(p->next, "[:>:]]", 6) == 0) {
+		EMIT(OEOW, 0);
+		NEXTn(6);
+		return;
+	}
+
+	if ((cs = allocset(p)) == NULL) {
+		/* allocset did set error status in p */
+		return;
+	}
+
+	if (EAT('^'))
+		invert++;	/* make note to invert set at end */
+	if (EAT(']'))
+		CHadd(cs, ']');
+	else if (EAT('-'))
+		CHadd(cs, '-');
+	while (MORE() && PEEK() != ']' && !SEETWO('-', ']'))
+		p_b_term(p, cs);
+	if (EAT('-'))
+		CHadd(cs, '-');
+	MUSTEAT(']', REG_EBRACK);
+
+	if (p->error != 0) {	/* don't mess things up further */
+		freeset(p, cs);
+		return;
+	}
+
+	if (p->g->cflags&REG_ICASE) {
+		int i;
+		int ci;
+
+		for (i = p->g->csetsize - 1; i >= 0; i--)
+			if (CHIN(cs, i) && isalpha(i)) {
+				ci = othercase(i);
+				if (ci != i)
+					CHadd(cs, ci);
+			}
+		if (cs->multis != NULL)
+			mccase(p, cs);
+	}
+	if (invert) {
+		int i;
+
+		for (i = p->g->csetsize - 1; i >= 0; i--)
+			if (CHIN(cs, i))
+				CHsub(cs, i);
+			else
+				CHadd(cs, i);
+		if (p->g->cflags&REG_NEWLINE)
+			CHsub(cs, '\n');
+		if (cs->multis != NULL)
+			mcinvert(p, cs);
+	}
+
+	assert(cs->multis == NULL);		/* xxx */
+
+	if (nch(p, cs) == 1) {		/* optimize singleton sets */
+		ordinary(p, firstch(p, cs));
+		freeset(p, cs);
+	} else
+		EMIT(OANYOF, freezeset(p, cs));
+}
+
+/*
+ - p_b_term - parse one term of a bracketed character list
+ */
+static void
+p_b_term(struct parse *p, cset *cs)
+{
+	char c;
+	char start, finish;
+	int i;
+
+	/* classify what we've got */
+	switch ((MORE()) ? PEEK() : '\0') {
+	case '[':
+		c = (MORE2()) ? PEEK2() : '\0';
+		break;
+	case '-':
+		SETERROR(REG_ERANGE);
+		return;			/* NOTE RETURN */
+		break;
+	default:
+		c = '\0';
+		break;
+	}
+
+	switch (c) {
+	case ':':		/* character class */
+		NEXT2();
+		REQUIRE(MORE(), REG_EBRACK);
+		c = PEEK();
+		REQUIRE(c != '-' && c != ']', REG_ECTYPE);
+		p_b_cclass(p, cs);
+		REQUIRE(MORE(), REG_EBRACK);
+		REQUIRE(EATTWO(':', ']'), REG_ECTYPE);
+		break;
+	case '=':		/* equivalence class */
+		NEXT2();
+		REQUIRE(MORE(), REG_EBRACK);
+		c = PEEK();
+		REQUIRE(c != '-' && c != ']', REG_ECOLLATE);
+		p_b_eclass(p, cs);
+		REQUIRE(MORE(), REG_EBRACK);
+		REQUIRE(EATTWO('=', ']'), REG_ECOLLATE);
+		break;
+	default:		/* symbol, ordinary character, or range */
+/* xxx revision needed for multichar stuff */
+		start = p_b_symbol(p);
+		if (SEE('-') && MORE2() && PEEK2() != ']') {
+			/* range */
+			NEXT();
+			if (EAT('-'))
+				finish = '-';
+			else
+				finish = p_b_symbol(p);
+		} else
+			finish = start;
+/* xxx what about signed chars here... */
+		REQUIRE(start <= finish, REG_ERANGE);
+		for (i = start; i <= finish; i++)
+			CHadd(cs, i);
+		break;
+	}
+}
+
+/*
+ - p_b_cclass - parse a character-class name and deal with it
+ */
+static void
+p_b_cclass(struct parse *p, cset *cs)
+{
+	char *sp = p->next;
+	struct cclass *cp;
+	size_t len;
+	const char *u;
+	char c;
+
+	while (MORE() && isalpha((uch)PEEK()))
+		NEXT();
+	len = p->next - sp;
+	for (cp = cclasses; cp->name != NULL; cp++)
+		if (strncmp(cp->name, sp, len) == 0 && cp->name[len] == '\0')
+			break;
+	if (cp->name == NULL) {
+		/* oops, didn't find it */
+		SETERROR(REG_ECTYPE);
+		return;
+	}
+
+	u = cp->chars;
+	while ((c = *u++) != '\0')
+		CHadd(cs, c);
+	for (u = cp->multis; *u != '\0'; u += strlen(u) + 1)
+		MCadd(p, cs, u);
+}
+
+/*
+ - p_b_eclass - parse an equivalence-class name and deal with it
+ *
+ * This implementation is incomplete. xxx
+ */
+static void
+p_b_eclass(struct parse *p, cset *cs)
+{
+	char c;
+
+	c = p_b_coll_elem(p, '=');
+	CHadd(cs, c);
+}
+
+/*
+ - p_b_symbol - parse a character or [..]ed multicharacter collating symbol
+ */
+static char			/* value of symbol */
+p_b_symbol(struct parse *p)
+{
+	char value;
+
+	REQUIRE(MORE(), REG_EBRACK);
+	if (!EATTWO('[', '.'))
+		return(GETNEXT());
+
+	/* collating symbol */
+	value = p_b_coll_elem(p, '.');
+	REQUIRE(EATTWO('.', ']'), REG_ECOLLATE);
+	return(value);
+}
+
+/*
+ - p_b_coll_elem - parse a collating-element name and look it up
+ */
+static char			/* value of collating element */
+p_b_coll_elem(struct parse *p,
+    int endc)			/* name ended by endc,']' */
+{
+	char *sp = p->next;
+	struct cname *cp;
+	size_t len;
+
+	while (MORE() && !SEETWO(endc, ']'))
+		NEXT();
+	if (!MORE()) {
+		SETERROR(REG_EBRACK);
+		return(0);
+	}
+	len = p->next - sp;
+	for (cp = cnames; cp->name != NULL; cp++)
+		if (strncmp(cp->name, sp, len) == 0 && strlen(cp->name) == len)
+			return(cp->code);	/* known name */
+	if (len == 1)
+		return(*sp);	/* single character */
+	SETERROR(REG_ECOLLATE);			/* neither */
+	return(0);
+}
+
+/*
+ - othercase - return the case counterpart of an alphabetic
+ */
+static char			/* if no counterpart, return ch */
+othercase(int ch)
+{
+	ch = (uch)ch;
+	assert(isalpha(ch));
+	if (isupper(ch))
+		return ((uch)tolower(ch));
+	else if (islower(ch))
+		return ((uch)toupper(ch));
+	else			/* peculiar, but could happen */
+		return(ch);
+}
+
+/*
+ - bothcases - emit a dualcase version of a two-case character
+ *
+ * Boy, is this implementation ever a kludge...
+ */
+static void
+bothcases(struct parse *p, int ch)
+{
+	char *oldnext = p->next;
+	char *oldend = p->end;
+	char bracket[3];
+
+	ch = (uch)ch;
+	assert(othercase(ch) != ch);	/* p_bracket() would recurse */
+	p->next = bracket;
+	p->end = bracket+2;
+	bracket[0] = ch;
+	bracket[1] = ']';
+	bracket[2] = '\0';
+	p_bracket(p);
+	assert(p->next == bracket+2);
+	p->next = oldnext;
+	p->end = oldend;
+}
+
+/*
+ - ordinary - emit an ordinary character
+ */
+static void
+ordinary(struct parse *p, int ch)
+{
+	cat_t *cap = p->g->categories;
+
+	if ((p->g->cflags&REG_ICASE) && isalpha((uch)ch) && othercase(ch) != ch)
+		bothcases(p, ch);
+	else {
+		EMIT(OCHAR, (uch)ch);
+		if (cap[ch] == 0)
+			cap[ch] = p->g->ncategories++;
+	}
+}
+
+/*
+ - nonnewline - emit REG_NEWLINE version of OANY
+ *
+ * Boy, is this implementation ever a kludge...
+ */
+static void
+nonnewline(struct parse *p)
+{
+	char *oldnext = p->next;
+	char *oldend = p->end;
+	char bracket[4];
+
+	p->next = bracket;
+	p->end = bracket+3;
+	bracket[0] = '^';
+	bracket[1] = '\n';
+	bracket[2] = ']';
+	bracket[3] = '\0';
+	p_bracket(p);
+	assert(p->next == bracket+3);
+	p->next = oldnext;
+	p->end = oldend;
+}
+
+/*
+ - repeat - generate code for a bounded repetition, recursively if needed
+ */
+static void
+repeat(struct parse *p,
+    sopno start,		/* operand from here to end of strip */
+    int from,			/* repeated from this number */
+    int to)			/* to this number of times (maybe INFINITY) */
+{
+	sopno finish = HERE();
+#	define	N	2
+#	define	INF	3
+#	define	REP(f, t)	((f)*8 + (t))
+#	define	MAP(n)	(((n) <= 1) ? (n) : ((n) == INFINITY) ? INF : N)
+	sopno copy;
+
+	if (p->error != 0)	/* head off possible runaway recursion */
+		return;
+
+	assert(from <= to);
+
+	switch (REP(MAP(from), MAP(to))) {
+	case REP(0, 0):			/* must be user doing this */
+		DROP(finish-start);	/* drop the operand */
+		break;
+	case REP(0, 1):			/* as x{1,1}? */
+	case REP(0, N):			/* as x{1,n}? */
+	case REP(0, INF):		/* as x{1,}? */
+		/* KLUDGE: emit y? as (y|) until subtle bug gets fixed */
+		INSERT(OCH_, start);		/* offset is wrong... */
+		repeat(p, start+1, 1, to);
+		ASTERN(OOR1, start);
+		AHEAD(start);			/* ... fix it */
+		EMIT(OOR2, 0);
+		AHEAD(THERE());
+		ASTERN(O_CH, THERETHERE());
+		break;
+	case REP(1, 1):			/* trivial case */
+		/* done */
+		break;
+	case REP(1, N):			/* as x?x{1,n-1} */
+		/* KLUDGE: emit y? as (y|) until subtle bug gets fixed */
+		INSERT(OCH_, start);
+		ASTERN(OOR1, start);
+		AHEAD(start);
+		EMIT(OOR2, 0);			/* offset very wrong... */
+		AHEAD(THERE());			/* ...so fix it */
+		ASTERN(O_CH, THERETHERE());
+		copy = dupl(p, start+1, finish+1);
+		assert(copy == finish+4);
+		repeat(p, copy, 1, to-1);
+		break;
+	case REP(1, INF):		/* as x+ */
+		INSERT(OPLUS_, start);
+		ASTERN(O_PLUS, start);
+		break;
+	case REP(N, N):			/* as xx{m-1,n-1} */
+		copy = dupl(p, start, finish);
+		repeat(p, copy, from-1, to-1);
+		break;
+	case REP(N, INF):		/* as xx{n-1,INF} */
+		copy = dupl(p, start, finish);
+		repeat(p, copy, from-1, to);
+		break;
+	default:			/* "can't happen" */
+		SETERROR(REG_ASSERT);	/* just in case */
+		break;
+	}
+}
+
+/*
+ - seterr - set an error condition
+ */
+static int			/* useless but makes type checking happy */
+seterr(struct parse *p, int e)
+{
+	if (p->error == 0)	/* keep earliest error condition */
+		p->error = e;
+	p->next = nuls;		/* try to bring things to a halt */
+	p->end = nuls;
+	return(0);		/* make the return value well-defined */
+}
+
+/*
+ - allocset - allocate a set of characters for []
+ */
+static cset *
+allocset(struct parse *p)
+{
+	int no = p->g->ncsets++;
+	size_t nc;
+	size_t nbytes;
+	cset *cs;
+	size_t css = (size_t)p->g->csetsize;
+	int i;
+
+	if (no >= p->ncsalloc) {	/* need another column of space */
+		void *ptr;
+
+		p->ncsalloc += CHAR_BIT;
+		nc = p->ncsalloc;
+		if (nc > SIZE_MAX / sizeof(cset))
+			goto nomem;
+		assert(nc % CHAR_BIT == 0);
+		nbytes = nc / CHAR_BIT * css;
+
+		ptr = (cset *)realloc((char *)p->g->sets, nc * sizeof(cset));
+		if (ptr == NULL)
+			goto nomem;
+		p->g->sets = ptr;
+
+		ptr = (uch *)realloc((char *)p->g->setbits, nbytes);
+		if (ptr == NULL)
+			goto nomem;
+		p->g->setbits = ptr;
+
+		for (i = 0; i < no; i++)
+			p->g->sets[i].ptr = p->g->setbits + css*(i/CHAR_BIT);
+
+		(void) memset((char *)p->g->setbits + (nbytes - css), 0, css);
+	}
+	/* XXX should not happen */
+	if (p->g->sets == NULL || p->g->setbits == NULL)
+		goto nomem;
+
+	cs = &p->g->sets[no];
+	cs->ptr = p->g->setbits + css*((no)/CHAR_BIT);
+	cs->mask = 1 << ((no) % CHAR_BIT);
+	cs->hash = 0;
+	cs->smultis = 0;
+	cs->multis = NULL;
+
+	return(cs);
+nomem:
+	free(p->g->sets);
+	p->g->sets = NULL;
+	free(p->g->setbits);
+	p->g->setbits = NULL;
+
+	SETERROR(REG_ESPACE);
+	/* caller's responsibility not to do set ops */
+	return(NULL);
+}
+
+/*
+ - freeset - free a now-unused set
+ */
+static void
+freeset(struct parse *p, cset *cs)
+{
+	size_t i;
+	cset *top = &p->g->sets[p->g->ncsets];
+	size_t css = (size_t)p->g->csetsize;
+
+	for (i = 0; i < css; i++)
+		CHsub(cs, i);
+	if (cs == top-1)	/* recover only the easy case */
+		p->g->ncsets--;
+}
+
+/*
+ - freezeset - final processing on a set of characters
+ *
+ * The main task here is merging identical sets.  This is usually a waste
+ * of time (although the hash code minimizes the overhead), but can win
+ * big if REG_ICASE is being used.  REG_ICASE, by the way, is why the hash
+ * is done using addition rather than xor -- all ASCII [aA] sets xor to
+ * the same value!
+ */
+static int			/* set number */
+freezeset(struct parse *p, cset *cs)
+{
+	uch h = cs->hash;
+	size_t i;
+	cset *top = &p->g->sets[p->g->ncsets];
+	cset *cs2;
+	size_t css = (size_t)p->g->csetsize;
+
+	/* look for an earlier one which is the same */
+	for (cs2 = &p->g->sets[0]; cs2 < top; cs2++)
+		if (cs2->hash == h && cs2 != cs) {
+			/* maybe */
+			for (i = 0; i < css; i++)
+				if (!!CHIN(cs2, i) != !!CHIN(cs, i))
+					break;		/* no */
+			if (i == css)
+				break;			/* yes */
+		}
+
+	if (cs2 < top) {	/* found one */
+		freeset(p, cs);
+		cs = cs2;
+	}
+
+	return((int)(cs - p->g->sets));
+}
+
+/*
+ - firstch - return first character in a set (which must have at least one)
+ */
+static int			/* character; there is no "none" value */
+firstch(struct parse *p, cset *cs)
+{
+	size_t i;
+	size_t css = (size_t)p->g->csetsize;
+
+	for (i = 0; i < css; i++)
+		if (CHIN(cs, i))
+			return((char)i);
+	assert(never);
+	return(0);		/* arbitrary */
+}
+
+/*
+ - nch - number of characters in a set
+ */
+static int
+nch(struct parse *p, cset *cs)
+{
+	size_t i;
+	size_t css = (size_t)p->g->csetsize;
+	int n = 0;
+
+	for (i = 0; i < css; i++)
+		if (CHIN(cs, i))
+			n++;
+	return(n);
+}
+
+/*
+ - mcadd - add a collating element to a cset
+ */
+static void
+mcadd( struct parse *p, cset *cs, const char *cp)
+{
+	size_t oldend = cs->smultis;
+	void *np;
+
+	cs->smultis += strlen(cp) + 1;
+	np = realloc(cs->multis, cs->smultis);
+	if (np == NULL) {
+		if (cs->multis)
+			free(cs->multis);
+		cs->multis = NULL;
+		SETERROR(REG_ESPACE);
+		return;
+	}
+	cs->multis = np;
+
+	llvm_strlcpy(cs->multis + oldend - 1, cp, cs->smultis - oldend + 1);
+}
+
+/*
+ - mcinvert - invert the list of collating elements in a cset
+ *
+ * This would have to know the set of possibilities.  Implementation
+ * is deferred.
+ */
+/* ARGSUSED */
+static void
+mcinvert(struct parse *p, cset *cs)
+{
+	assert(cs->multis == NULL);	/* xxx */
+}
+
+/*
+ - mccase - add case counterparts of the list of collating elements in a cset
+ *
+ * This would have to know the set of possibilities.  Implementation
+ * is deferred.
+ */
+/* ARGSUSED */
+static void
+mccase(struct parse *p, cset *cs)
+{
+	assert(cs->multis == NULL);	/* xxx */
+}
+
+/*
+ - isinsets - is this character in any sets?
+ */
+static int			/* predicate */
+isinsets(struct re_guts *g, int c)
+{
+	uch *col;
+	int i;
+	int ncols = (g->ncsets+(CHAR_BIT-1)) / CHAR_BIT;
+	unsigned uc = (uch)c;
+
+	for (i = 0, col = g->setbits; i < ncols; i++, col += g->csetsize)
+		if (col[uc] != 0)
+			return(1);
+	return(0);
+}
+
+/*
+ - samesets - are these two characters in exactly the same sets?
+ */
+static int			/* predicate */
+samesets(struct re_guts *g, int c1, int c2)
+{
+	uch *col;
+	int i;
+	int ncols = (g->ncsets+(CHAR_BIT-1)) / CHAR_BIT;
+	unsigned uc1 = (uch)c1;
+	unsigned uc2 = (uch)c2;
+
+	for (i = 0, col = g->setbits; i < ncols; i++, col += g->csetsize)
+		if (col[uc1] != col[uc2])
+			return(0);
+	return(1);
+}
+
+/*
+ - categorize - sort out character categories
+ */
+static void
+categorize(struct parse *p, struct re_guts *g)
+{
+	cat_t *cats = g->categories;
+	int c;
+	int c2;
+	cat_t cat;
+
+	/* avoid making error situations worse */
+	if (p->error != 0)
+		return;
+
+	for (c = CHAR_MIN; c <= CHAR_MAX; c++)
+		if (cats[c] == 0 && isinsets(g, c)) {
+			cat = g->ncategories++;
+			cats[c] = cat;
+			for (c2 = c+1; c2 <= CHAR_MAX; c2++)
+				if (cats[c2] == 0 && samesets(g, c, c2))
+					cats[c2] = cat;
+		}
+}
+
+/*
+ - dupl - emit a duplicate of a bunch of sops
+ */
+static sopno			/* start of duplicate */
+dupl(struct parse *p,
+    sopno start,		/* from here */
+    sopno finish)		/* to this less one */
+{
+	sopno ret = HERE();
+	sopno len = finish - start;
+
+	assert(finish >= start);
+	if (len == 0)
+		return(ret);
+	enlarge(p, p->ssize + len);	/* this many unexpected additions */
+	assert(p->ssize >= p->slen + len);
+	(void) memmove((char *)(p->strip + p->slen),
+		(char *)(p->strip + start), (size_t)len*sizeof(sop));
+	p->slen += len;
+	return(ret);
+}
+
+/*
+ - doemit - emit a strip operator
+ *
+ * It might seem better to implement this as a macro with a function as
+ * hard-case backup, but it's just too big and messy unless there are
+ * some changes to the data structures.  Maybe later.
+ */
+static void
+doemit(struct parse *p, sop op, size_t opnd)
+{
+	/* avoid making error situations worse */
+	if (p->error != 0)
+		return;
+
+	/* deal with oversize operands ("can't happen", more or less) */
+	assert(opnd < 1<<OPSHIFT);
+
+	/* deal with undersized strip */
+	if (p->slen >= p->ssize)
+		enlarge(p, (p->ssize+1) / 2 * 3);	/* +50% */
+	assert(p->slen < p->ssize);
+
+	/* finally, it's all reduced to the easy case */
+	p->strip[p->slen++] = SOP(op, opnd);
+}
+
+/*
+ - doinsert - insert a sop into the strip
+ */
+static void
+doinsert(struct parse *p, sop op, size_t opnd, sopno pos)
+{
+	sopno sn;
+	sop s;
+	int i;
+
+	/* avoid making error situations worse */
+	if (p->error != 0)
+		return;
+
+	sn = HERE();
+	EMIT(op, opnd);		/* do checks, ensure space */
+	assert(HERE() == sn+1);
+	s = p->strip[sn];
+
+	/* adjust paren pointers */
+	assert(pos > 0);
+	for (i = 1; i < NPAREN; i++) {
+		if (p->pbegin[i] >= pos) {
+			p->pbegin[i]++;
+		}
+		if (p->pend[i] >= pos) {
+			p->pend[i]++;
+		}
+	}
+
+	memmove((char *)&p->strip[pos+1], (char *)&p->strip[pos],
+						(HERE()-pos-1)*sizeof(sop));
+	p->strip[pos] = s;
+}
+
+/*
+ - dofwd - complete a forward reference
+ */
+static void
+dofwd(struct parse *p, sopno pos, sop value)
+{
+	/* avoid making error situations worse */
+	if (p->error != 0)
+		return;
+
+	assert(value < 1<<OPSHIFT);
+	p->strip[pos] = OP(p->strip[pos]) | value;
+}
+
+/*
+ - enlarge - enlarge the strip
+ */
+static void
+enlarge(struct parse *p, sopno size)
+{
+	sop *sp;
+
+	if (p->ssize >= size)
+		return;
+
+	if ((uintptr_t)size > SIZE_MAX / sizeof(sop)) {
+		SETERROR(REG_ESPACE);
+		return;
+	}
+
+	sp = (sop *)realloc(p->strip, size*sizeof(sop));
+	if (sp == NULL) {
+		SETERROR(REG_ESPACE);
+		return;
+	}
+	p->strip = sp;
+	p->ssize = size;
+}
+
+/*
+ - stripsnug - compact the strip
+ */
+static void
+stripsnug(struct parse *p, struct re_guts *g)
+{
+	g->nstates = p->slen;
+	if ((uintptr_t)p->slen > SIZE_MAX / sizeof(sop)) {
+		g->strip = p->strip;
+		SETERROR(REG_ESPACE);
+		return;
+	}
+
+	g->strip = (sop *)realloc((char *)p->strip, p->slen * sizeof(sop));
+	if (g->strip == NULL) {
+		SETERROR(REG_ESPACE);
+		g->strip = p->strip;
+	}
+}
+
+/*
+ - findmust - fill in must and mlen with longest mandatory literal string
+ *
+ * This algorithm could do fancy things like analyzing the operands of |
+ * for common subsequences.  Someday.  This code is simple and finds most
+ * of the interesting cases.
+ *
+ * Note that must and mlen got initialized during setup.
+ */
+static void
+findmust(struct parse *p, struct re_guts *g)
+{
+	sop *scan;
+	sop *start = 0; /* start initialized in the default case, after that */
+	sop *newstart = 0; /* newstart was initialized in the OCHAR case */
+	sopno newlen;
+	sop s;
+	char *cp;
+	sopno i;
+
+	/* avoid making error situations worse */
+	if (p->error != 0)
+		return;
+
+	/* find the longest OCHAR sequence in strip */
+	newlen = 0;
+	scan = g->strip + 1;
+	do {
+		s = *scan++;
+		switch (OP(s)) {
+		case OCHAR:		/* sequence member */
+			if (newlen == 0)		/* new sequence */
+				newstart = scan - 1;
+			newlen++;
+			break;
+		case OPLUS_:		/* things that don't break one */
+		case OLPAREN:
+		case ORPAREN:
+			break;
+		case OQUEST_:		/* things that must be skipped */
+		case OCH_:
+			scan--;
+			do {
+				scan += OPND(s);
+				s = *scan;
+				/* assert() interferes w debug printouts */
+				if (OP(s) != O_QUEST && OP(s) != O_CH &&
+							OP(s) != OOR2) {
+					g->iflags |= REGEX_BAD;
+					return;
+				}
+			} while (OP(s) != O_QUEST && OP(s) != O_CH);
+			/* fallthrough */
+		default:		/* things that break a sequence */
+			if (newlen > g->mlen) {		/* ends one */
+				start = newstart;
+				g->mlen = newlen;
+			}
+			newlen = 0;
+			break;
+		}
+	} while (OP(s) != OEND);
+
+	if (g->mlen == 0)		/* there isn't one */
+		return;
+
+	/* turn it into a character string */
+	g->must = malloc((size_t)g->mlen + 1);
+	if (g->must == NULL) {		/* argh; just forget it */
+		g->mlen = 0;
+		return;
+	}
+	cp = g->must;
+	scan = start;
+	for (i = g->mlen; i > 0; i--) {
+		while (OP(s = *scan++) != OCHAR)
+			continue;
+		assert(cp < g->must + g->mlen);
+		*cp++ = (char)OPND(s);
+	}
+	assert(cp == g->must + g->mlen);
+	*cp++ = '\0';		/* just on general principles */
+}
+
+/*
+ - pluscount - count + nesting
+ */
+static sopno			/* nesting depth */
+pluscount(struct parse *p, struct re_guts *g)
+{
+	sop *scan;
+	sop s;
+	sopno plusnest = 0;
+	sopno maxnest = 0;
+
+	if (p->error != 0)
+		return(0);	/* there may not be an OEND */
+
+	scan = g->strip + 1;
+	do {
+		s = *scan++;
+		switch (OP(s)) {
+		case OPLUS_:
+			plusnest++;
+			break;
+		case O_PLUS:
+			if (plusnest > maxnest)
+				maxnest = plusnest;
+			plusnest--;
+			break;
+		}
+	} while (OP(s) != OEND);
+	if (plusnest != 0)
+		g->iflags |= REGEX_BAD;
+	return(maxnest);
+}