]> git.vpit.fr Git - perl/modules/re-engine-Hooks.git/blobdiff - src/5012005/regexec.c
Add support for perl 5.12.5 and 5.17.[678]
[perl/modules/re-engine-Hooks.git] / src / 5012005 / regexec.c
diff --git a/src/5012005/regexec.c b/src/5012005/regexec.c
new file mode 100644 (file)
index 0000000..07b32ae
--- /dev/null
@@ -0,0 +1,6291 @@
+/*    regexec.c
+ */
+
+/*
+ *     One Ring to rule them all, One Ring to find them
+ &
+ *     [p.v of _The Lord of the Rings_, opening poem]
+ *     [p.50 of _The Lord of the Rings_, I/iii: "The Shadow of the Past"]
+ *     [p.254 of _The Lord of the Rings_, II/ii: "The Council of Elrond"]
+ */
+
+/* This file contains functions for executing a regular expression.  See
+ * also regcomp.c which funnily enough, contains functions for compiling
+ * a regular expression.
+ *
+ * This file is also copied at build time to ext/re/re_exec.c, where
+ * it's built with -DPERL_EXT_RE_BUILD -DPERL_EXT_RE_DEBUG -DPERL_EXT.
+ * This causes the main functions to be compiled under new names and with
+ * debugging support added, which makes "use re 'debug'" work.
+ */
+
+/* NOTE: this is derived from Henry Spencer's regexp code, and should not
+ * confused with the original package (see point 3 below).  Thanks, Henry!
+ */
+
+/* Additional note: this code is very heavily munged from Henry's version
+ * in places.  In some spots I've traded clarity for efficiency, so don't
+ * blame Henry for some of the lack of readability.
+ */
+
+/* The names of the functions have been changed from regcomp and
+ * regexec to  pregcomp and pregexec in order to avoid conflicts
+ * with the POSIX routines of the same names.
+*/
+
+#ifdef PERL_EXT_RE_BUILD
+#include "re_top.h"
+#endif
+
+/*
+ * pregcomp and pregexec -- regsub and regerror are not used in perl
+ *
+ *     Copyright (c) 1986 by University of Toronto.
+ *     Written by Henry Spencer.  Not derived from licensed software.
+ *
+ *     Permission is granted to anyone to use this software for any
+ *     purpose on any computer system, and to redistribute it freely,
+ *     subject to the following restrictions:
+ *
+ *     1. The author is not responsible for the consequences of use of
+ *             this software, no matter how awful, even if they arise
+ *             from defects in it.
+ *
+ *     2. The origin of this software must not be misrepresented, either
+ *             by explicit claim or by omission.
+ *
+ *     3. Altered versions must be plainly marked as such, and must not
+ *             be misrepresented as being the original software.
+ *
+ ****    Alterations to Henry's code are...
+ ****
+ ****    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
+ ****    2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ ****    by Larry Wall and others
+ ****
+ ****    You may distribute under the terms of either the GNU General Public
+ ****    License or the Artistic License, as specified in the README file.
+ *
+ * Beware that some of this code is subtly aware of the way operator
+ * precedence is structured in regular expressions.  Serious changes in
+ * regular-expression syntax might require a total rethink.
+ */
+#include "EXTERN.h"
+#define PERL_IN_REGEXEC_C
+#include "perl.h"
+#include "re_defs.h"
+
+#ifdef PERL_IN_XSUB_RE
+#  include "re_comp.h"
+#else
+#  include "regcomp.h"
+#endif
+
+#define RF_tainted     1               /* tainted information used? */
+#define RF_warned      2               /* warned about big count? */
+
+#define RF_utf8                8               /* Pattern contains multibyte chars? */
+
+#define UTF ((PL_reg_flags & RF_utf8) != 0)
+
+#define RS_init                1               /* eval environment created */
+#define RS_set         2               /* replsv value is set */
+
+#ifndef STATIC
+#define        STATIC  static
+#endif
+
+#define REGINCLASS(prog,p,c)  (ANYOF_FLAGS(p) ? reginclass(prog,p,c,0,0) : ANYOF_BITMAP_TEST(p,*(c)))
+
+/*
+ * Forwards.
+ */
+
+#define CHR_SVLEN(sv) (do_utf8 ? sv_len_utf8(sv) : SvCUR(sv))
+#define CHR_DIST(a,b) (PL_reg_match_utf8 ? utf8_distance(a,b) : a - b)
+
+#define HOPc(pos,off) \
+       (char *)(PL_reg_match_utf8 \
+           ? reghop3((U8*)pos, off, (U8*)(off >= 0 ? PL_regeol : PL_bostr)) \
+           : (U8*)(pos + off))
+#define HOPBACKc(pos, off) \
+       (char*)(PL_reg_match_utf8\
+           ? reghopmaybe3((U8*)pos, -off, (U8*)PL_bostr) \
+           : (pos - off >= PL_bostr)           \
+               ? (U8*)pos - off                \
+               : NULL)
+
+#define HOP3(pos,off,lim) (PL_reg_match_utf8 ? reghop3((U8*)(pos), off, (U8*)(lim)) : (U8*)(pos + off))
+#define HOP3c(pos,off,lim) ((char*)HOP3(pos,off,lim))
+
+/* these are unrolled below in the CCC_TRY_XXX defined */
+#define LOAD_UTF8_CHARCLASS(class,str) STMT_START { \
+    if (!CAT2(PL_utf8_,class)) { bool ok; ENTER; save_re_context(); ok=CAT2(is_utf8_,class)((const U8*)str); assert(ok); LEAVE; } } STMT_END
+
+/* Doesn't do an assert to verify that is correct */
+#define LOAD_UTF8_CHARCLASS_NO_CHECK(class) STMT_START { \
+    if (!CAT2(PL_utf8_,class)) { bool ok; ENTER; save_re_context(); ok=CAT2(is_utf8_,class)((const U8*)" "); LEAVE; } } STMT_END
+
+#define LOAD_UTF8_CHARCLASS_ALNUM() LOAD_UTF8_CHARCLASS(alnum,"a")
+#define LOAD_UTF8_CHARCLASS_DIGIT() LOAD_UTF8_CHARCLASS(digit,"0")
+#define LOAD_UTF8_CHARCLASS_SPACE() LOAD_UTF8_CHARCLASS(space," ")
+
+#define LOAD_UTF8_CHARCLASS_GCB()  /* Grapheme cluster boundaries */        \
+       LOAD_UTF8_CHARCLASS(X_begin, " ");                                  \
+       LOAD_UTF8_CHARCLASS(X_non_hangul, "A");                             \
+       /* These are utf8 constants, and not utf-ebcdic constants, so the   \
+           * assert should likely and hopefully fail on an EBCDIC machine */ \
+       LOAD_UTF8_CHARCLASS(X_extend, "\xcc\x80"); /* U+0300 */             \
+                                                                           \
+       /* No asserts are done for these, in case called on an early        \
+           * Unicode version in which they map to nothing */               \
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_prepend);/* U+0E40 "\xe0\xb9\x80" */ \
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_L);          /* U+1100 "\xe1\x84\x80" */ \
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_LV);     /* U+AC00 "\xea\xb0\x80" */ \
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_LVT);    /* U+AC01 "\xea\xb0\x81" */ \
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_LV_LVT_V);/* U+AC01 "\xea\xb0\x81" */\
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_T);      /* U+11A8 "\xe1\x86\xa8" */ \
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_V)       /* U+1160 "\xe1\x85\xa0" */  
+
+/* 
+   We dont use PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS as the direct test
+   so that it is possible to override the option here without having to 
+   rebuild the entire core. as we are required to do if we change regcomp.h
+   which is where PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS is defined.
+*/
+#if PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS
+#define BROKEN_UNICODE_CHARCLASS_MAPPINGS
+#endif
+
+#ifdef BROKEN_UNICODE_CHARCLASS_MAPPINGS
+#define LOAD_UTF8_CHARCLASS_PERL_WORD()   LOAD_UTF8_CHARCLASS_ALNUM()
+#define LOAD_UTF8_CHARCLASS_PERL_SPACE()  LOAD_UTF8_CHARCLASS_SPACE()
+#define LOAD_UTF8_CHARCLASS_POSIX_DIGIT() LOAD_UTF8_CHARCLASS_DIGIT()
+#define RE_utf8_perl_word   PL_utf8_alnum
+#define RE_utf8_perl_space  PL_utf8_space
+#define RE_utf8_posix_digit PL_utf8_digit
+#define perl_word  alnum
+#define perl_space space
+#define posix_digit digit
+#else
+#define LOAD_UTF8_CHARCLASS_PERL_WORD()   LOAD_UTF8_CHARCLASS(perl_word,"a")
+#define LOAD_UTF8_CHARCLASS_PERL_SPACE()  LOAD_UTF8_CHARCLASS(perl_space," ")
+#define LOAD_UTF8_CHARCLASS_POSIX_DIGIT() LOAD_UTF8_CHARCLASS(posix_digit,"0")
+#define RE_utf8_perl_word   PL_utf8_perl_word
+#define RE_utf8_perl_space  PL_utf8_perl_space
+#define RE_utf8_posix_digit PL_utf8_posix_digit
+#endif
+
+
+#define CCC_TRY_AFF(NAME,NAMEL,CLASS,STR,LCFUNC_utf8,FUNC,LCFUNC)                          \
+        case NAMEL:                                                              \
+            PL_reg_flags |= RF_tainted;                                                 \
+            /* FALL THROUGH */                                                          \
+        case NAME:                                                                     \
+            if (!nextchr)                                                               \
+                sayNO;                                                                  \
+            if (do_utf8 && UTF8_IS_CONTINUED(nextchr)) {                                \
+                if (!CAT2(PL_utf8_,CLASS)) {                                            \
+                    bool ok;                                                            \
+                    ENTER;                                                              \
+                    save_re_context();                                                  \
+                    ok=CAT2(is_utf8_,CLASS)((const U8*)STR);                            \
+                    assert(ok);                                                         \
+                    LEAVE;                                                              \
+                }                                                                       \
+                if (!(OP(scan) == NAME                                                  \
+                    ? (bool)swash_fetch(CAT2(PL_utf8_,CLASS), (U8*)locinput, do_utf8)   \
+                    : LCFUNC_utf8((U8*)locinput)))                                      \
+                {                                                                       \
+                    sayNO;                                                              \
+                }                                                                       \
+                locinput += PL_utf8skip[nextchr];                                       \
+                nextchr = UCHARAT(locinput);                                            \
+                break;                                                                  \
+            }                                                                           \
+            if (!(OP(scan) == NAME ? FUNC(nextchr) : LCFUNC(nextchr)))                  \
+                sayNO;                                                                  \
+            nextchr = UCHARAT(++locinput);                                              \
+            break
+
+#define CCC_TRY_NEG(NAME,NAMEL,CLASS,STR,LCFUNC_utf8,FUNC,LCFUNC)                        \
+        case NAMEL:                                                              \
+            PL_reg_flags |= RF_tainted;                                                 \
+            /* FALL THROUGH */                                                          \
+        case NAME :                                                                     \
+            if (!nextchr && locinput >= PL_regeol)                                      \
+                sayNO;                                                                  \
+            if (do_utf8 && UTF8_IS_CONTINUED(nextchr)) {                                \
+                if (!CAT2(PL_utf8_,CLASS)) {                                            \
+                    bool ok;                                                            \
+                    ENTER;                                                              \
+                    save_re_context();                                                  \
+                    ok=CAT2(is_utf8_,CLASS)((const U8*)STR);                            \
+                    assert(ok);                                                         \
+                    LEAVE;                                                              \
+                }                                                                       \
+                if ((OP(scan) == NAME                                                  \
+                    ? (bool)swash_fetch(CAT2(PL_utf8_,CLASS), (U8*)locinput, do_utf8)    \
+                    : LCFUNC_utf8((U8*)locinput)))                                      \
+                {                                                                       \
+                    sayNO;                                                              \
+                }                                                                       \
+                locinput += PL_utf8skip[nextchr];                                       \
+                nextchr = UCHARAT(locinput);                                            \
+                break;                                                                  \
+            }                                                                           \
+            if ((OP(scan) == NAME ? FUNC(nextchr) : LCFUNC(nextchr)))                   \
+                sayNO;                                                                  \
+            nextchr = UCHARAT(++locinput);                                              \
+            break
+
+
+
+
+
+/* TODO: Combine JUMPABLE and HAS_TEXT to cache OP(rn) */
+
+/* for use after a quantifier and before an EXACT-like node -- japhy */
+/* it would be nice to rework regcomp.sym to generate this stuff. sigh */
+#define JUMPABLE(rn) (      \
+    OP(rn) == OPEN ||       \
+    (OP(rn) == CLOSE && (!cur_eval || cur_eval->u.eval.close_paren != ARG(rn))) || \
+    OP(rn) == EVAL ||   \
+    OP(rn) == SUSPEND || OP(rn) == IFMATCH || \
+    OP(rn) == PLUS || OP(rn) == MINMOD || \
+    OP(rn) == KEEPS || (PL_regkind[OP(rn)] == VERB) || \
+    (PL_regkind[OP(rn)] == CURLY && ARG1(rn) > 0) \
+)
+#define IS_EXACT(rn) (PL_regkind[OP(rn)] == EXACT)
+
+#define HAS_TEXT(rn) ( IS_EXACT(rn) || PL_regkind[OP(rn)] == REF )
+
+#if 0 
+/* Currently these are only used when PL_regkind[OP(rn)] == EXACT so
+   we don't need this definition. */
+#define IS_TEXT(rn)   ( OP(rn)==EXACT   || OP(rn)==REF   || OP(rn)==NREF   )
+#define IS_TEXTF(rn)  ( OP(rn)==EXACTF  || OP(rn)==REFF  || OP(rn)==NREFF  )
+#define IS_TEXTFL(rn) ( OP(rn)==EXACTFL || OP(rn)==REFFL || OP(rn)==NREFFL )
+
+#else
+/* ... so we use this as its faster. */
+#define IS_TEXT(rn)   ( OP(rn)==EXACT   )
+#define IS_TEXTF(rn)  ( OP(rn)==EXACTF  )
+#define IS_TEXTFL(rn) ( OP(rn)==EXACTFL )
+
+#endif
+
+/*
+  Search for mandatory following text node; for lookahead, the text must
+  follow but for lookbehind (rn->flags != 0) we skip to the next step.
+*/
+#define FIND_NEXT_IMPT(rn) STMT_START { \
+    while (JUMPABLE(rn)) { \
+       const OPCODE type = OP(rn); \
+       if (type == SUSPEND || PL_regkind[type] == CURLY) \
+           rn = NEXTOPER(NEXTOPER(rn)); \
+       else if (type == PLUS) \
+           rn = NEXTOPER(rn); \
+       else if (type == IFMATCH) \
+           rn = (rn->flags == 0) ? NEXTOPER(NEXTOPER(rn)) : rn + ARG(rn); \
+       else rn += NEXT_OFF(rn); \
+    } \
+} STMT_END 
+
+
+static void restore_pos(pTHX_ void *arg);
+
+STATIC CHECKPOINT
+S_regcppush(pTHX_ I32 parenfloor)
+{
+    dVAR;
+    const int retval = PL_savestack_ix;
+#define REGCP_PAREN_ELEMS 4
+    const int paren_elems_to_push = (PL_regsize - parenfloor) * REGCP_PAREN_ELEMS;
+    int p;
+    GET_RE_DEBUG_FLAGS_DECL;
+
+    if (paren_elems_to_push < 0)
+       Perl_croak(aTHX_ "panic: paren_elems_to_push < 0");
+
+#define REGCP_OTHER_ELEMS 7
+    SSGROW(paren_elems_to_push + REGCP_OTHER_ELEMS);
+    
+    for (p = PL_regsize; p > parenfloor; p--) {
+/* REGCP_PARENS_ELEMS are pushed per pairs of parentheses. */
+       SSPUSHINT(PL_regoffs[p].end);
+       SSPUSHINT(PL_regoffs[p].start);
+       SSPUSHPTR(PL_reg_start_tmp[p]);
+       SSPUSHINT(p);
+       DEBUG_BUFFERS_r(PerlIO_printf(Perl_debug_log,
+         "     saving \\%"UVuf" %"IVdf"(%"IVdf")..%"IVdf"\n",
+                     (UV)p, (IV)PL_regoffs[p].start,
+                     (IV)(PL_reg_start_tmp[p] - PL_bostr),
+                     (IV)PL_regoffs[p].end
+       ));
+    }
+/* REGCP_OTHER_ELEMS are pushed in any case, parentheses or no. */
+    SSPUSHPTR(PL_regoffs);
+    SSPUSHINT(PL_regsize);
+    SSPUSHINT(*PL_reglastparen);
+    SSPUSHINT(*PL_reglastcloseparen);
+    SSPUSHPTR(PL_reginput);
+#define REGCP_FRAME_ELEMS 2
+/* REGCP_FRAME_ELEMS are part of the REGCP_OTHER_ELEMS and
+ * are needed for the regexp context stack bookkeeping. */
+    SSPUSHINT(paren_elems_to_push + REGCP_OTHER_ELEMS - REGCP_FRAME_ELEMS);
+    SSPUSHINT(SAVEt_REGCONTEXT); /* Magic cookie. */
+
+    return retval;
+}
+
+/* These are needed since we do not localize EVAL nodes: */
+#define REGCP_SET(cp)                                           \
+    DEBUG_STATE_r(                                              \
+            PerlIO_printf(Perl_debug_log,                      \
+               "  Setting an EVAL scope, savestack=%"IVdf"\n", \
+               (IV)PL_savestack_ix));                          \
+    cp = PL_savestack_ix
+
+#define REGCP_UNWIND(cp)                                        \
+    DEBUG_STATE_r(                                              \
+        if (cp != PL_savestack_ix)                             \
+           PerlIO_printf(Perl_debug_log,                       \
+               "  Clearing an EVAL scope, savestack=%"IVdf"..%"IVdf"\n", \
+               (IV)(cp), (IV)PL_savestack_ix));                \
+    regcpblow(cp)
+
+STATIC char *
+S_regcppop(pTHX_ const regexp *rex)
+{
+    dVAR;
+    U32 i;
+    char *input;
+    GET_RE_DEBUG_FLAGS_DECL;
+
+    PERL_ARGS_ASSERT_REGCPPOP;
+
+    /* Pop REGCP_OTHER_ELEMS before the parentheses loop starts. */
+    i = SSPOPINT;
+    assert(i == SAVEt_REGCONTEXT); /* Check that the magic cookie is there. */
+    i = SSPOPINT; /* Parentheses elements to pop. */
+    input = (char *) SSPOPPTR;
+    *PL_reglastcloseparen = SSPOPINT;
+    *PL_reglastparen = SSPOPINT;
+    PL_regsize = SSPOPINT;
+    PL_regoffs=(regexp_paren_pair *) SSPOPPTR;
+
+    
+    /* Now restore the parentheses context. */
+    for (i -= (REGCP_OTHER_ELEMS - REGCP_FRAME_ELEMS);
+        i > 0; i -= REGCP_PAREN_ELEMS) {
+       I32 tmps;
+       U32 paren = (U32)SSPOPINT;
+       PL_reg_start_tmp[paren] = (char *) SSPOPPTR;
+       PL_regoffs[paren].start = SSPOPINT;
+       tmps = SSPOPINT;
+       if (paren <= *PL_reglastparen)
+           PL_regoffs[paren].end = tmps;
+       DEBUG_BUFFERS_r(
+           PerlIO_printf(Perl_debug_log,
+                         "     restoring \\%"UVuf" to %"IVdf"(%"IVdf")..%"IVdf"%s\n",
+                         (UV)paren, (IV)PL_regoffs[paren].start,
+                         (IV)(PL_reg_start_tmp[paren] - PL_bostr),
+                         (IV)PL_regoffs[paren].end,
+                         (paren > *PL_reglastparen ? "(no)" : ""));
+       );
+    }
+    DEBUG_BUFFERS_r(
+       if (*PL_reglastparen + 1 <= rex->nparens) {
+           PerlIO_printf(Perl_debug_log,
+                         "     restoring \\%"IVdf"..\\%"IVdf" to undef\n",
+                         (IV)(*PL_reglastparen + 1), (IV)rex->nparens);
+       }
+    );
+#if 1
+    /* It would seem that the similar code in regtry()
+     * already takes care of this, and in fact it is in
+     * a better location to since this code can #if 0-ed out
+     * but the code in regtry() is needed or otherwise tests
+     * requiring null fields (pat.t#187 and split.t#{13,14}
+     * (as of patchlevel 7877)  will fail.  Then again,
+     * this code seems to be necessary or otherwise
+     * this erroneously leaves $1 defined: "1" =~ /^(?:(\d)x)?\d$/
+     * --jhi updated by dapm */
+    for (i = *PL_reglastparen + 1; i <= rex->nparens; i++) {
+       if (i > PL_regsize)
+           PL_regoffs[i].start = -1;
+       PL_regoffs[i].end = -1;
+    }
+#endif
+    return input;
+}
+
+#define regcpblow(cp) LEAVE_SCOPE(cp)  /* Ignores regcppush()ed data. */
+
+/*
+ * pregexec and friends
+ */
+
+#ifndef PERL_IN_XSUB_RE
+/*
+ - pregexec - match a regexp against a string
+ */
+I32
+Perl_pregexec(pTHX_ REGEXP * const prog, char* stringarg, register char *strend,
+        char *strbeg, I32 minend, SV *screamer, U32 nosave)
+/* strend: pointer to null at end of string */
+/* strbeg: real beginning of string */
+/* minend: end of match must be >=minend after stringarg. */
+/* nosave: For optimizations. */
+{
+    PERL_ARGS_ASSERT_PREGEXEC;
+
+    return
+       regexec_flags(prog, stringarg, strend, strbeg, minend, screamer, NULL,
+                     nosave ? 0 : REXEC_COPY_STR);
+}
+#endif
+
+/*
+ * Need to implement the following flags for reg_anch:
+ *
+ * USE_INTUIT_NOML             - Useful to call re_intuit_start() first
+ * USE_INTUIT_ML
+ * INTUIT_AUTORITATIVE_NOML    - Can trust a positive answer
+ * INTUIT_AUTORITATIVE_ML
+ * INTUIT_ONCE_NOML            - Intuit can match in one location only.
+ * INTUIT_ONCE_ML
+ *
+ * Another flag for this function: SECOND_TIME (so that float substrs
+ * with giant delta may be not rechecked).
+ */
+
+/* Assumptions: if ANCH_GPOS, then strpos is anchored. XXXX Check GPOS logic */
+
+/* If SCREAM, then SvPVX_const(sv) should be compatible with strpos and strend.
+   Otherwise, only SvCUR(sv) is used to get strbeg. */
+
+/* XXXX We assume that strpos is strbeg unless sv. */
+
+/* XXXX Some places assume that there is a fixed substring.
+       An update may be needed if optimizer marks as "INTUITable"
+       RExen without fixed substrings.  Similarly, it is assumed that
+       lengths of all the strings are no more than minlen, thus they
+       cannot come from lookahead.
+       (Or minlen should take into account lookahead.) 
+  NOTE: Some of this comment is not correct. minlen does now take account
+  of lookahead/behind. Further research is required. -- demerphq
+
+*/
+
+/* A failure to find a constant substring means that there is no need to make
+   an expensive call to REx engine, thus we celebrate a failure.  Similarly,
+   finding a substring too deep into the string means that less calls to
+   regtry() should be needed.
+
+   REx compiler's optimizer found 4 possible hints:
+       a) Anchored substring;
+       b) Fixed substring;
+       c) Whether we are anchored (beginning-of-line or \G);
+       d) First node (of those at offset 0) which may distingush positions;
+   We use a)b)d) and multiline-part of c), and try to find a position in the
+   string which does not contradict any of them.
+ */
+
+/* Most of decisions we do here should have been done at compile time.
+   The nodes of the REx which we used for the search should have been
+   deleted from the finite automaton. */
+
+char *
+Perl_re_intuit_start(pTHX_ REGEXP * const rx, SV *sv, char *strpos,
+                    char *strend, const U32 flags, re_scream_pos_data *data)
+{
+    dVAR;
+    struct regexp *const prog = (struct regexp *)SvANY(rx);
+    register I32 start_shift = 0;
+    /* Should be nonnegative! */
+    register I32 end_shift   = 0;
+    register char *s;
+    register SV *check;
+    char *strbeg;
+    char *t;
+    const bool do_utf8 = (sv && SvUTF8(sv)) ? 1 : 0; /* if no sv we have to assume bytes */
+    I32 ml_anch;
+    register char *other_last = NULL;  /* other substr checked before this */
+    char *check_at = NULL;             /* check substr found at this pos */
+    const I32 multiline = prog->extflags & RXf_PMf_MULTILINE;
+    RXi_GET_DECL(prog,progi);
+#ifdef DEBUGGING
+    const char * const i_strpos = strpos;
+#endif
+    GET_RE_DEBUG_FLAGS_DECL;
+
+    PERL_ARGS_ASSERT_RE_INTUIT_START;
+
+    RX_MATCH_UTF8_set(rx,do_utf8);
+
+    if (RX_UTF8(rx)) {
+       PL_reg_flags |= RF_utf8;
+    }
+    DEBUG_EXECUTE_r( 
+        debug_start_match(rx, do_utf8, strpos, strend, 
+            sv ? "Guessing start of match in sv for"
+               : "Guessing start of match in string for");
+             );
+
+    /* CHR_DIST() would be more correct here but it makes things slow. */
+    if (prog->minlen > strend - strpos) {
+       DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+                             "String too short... [re_intuit_start]\n"));
+       goto fail;
+    }
+                
+    strbeg = (sv && SvPOK(sv)) ? strend - SvCUR(sv) : strpos;
+    PL_regeol = strend;
+    if (do_utf8) {
+       if (!prog->check_utf8 && prog->check_substr)
+           to_utf8_substr(prog);
+       check = prog->check_utf8;
+    } else {
+       if (!prog->check_substr && prog->check_utf8)
+           to_byte_substr(prog);
+       check = prog->check_substr;
+    }
+    if (check == &PL_sv_undef) {
+       DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+               "Non-utf8 string cannot match utf8 check string\n"));
+       goto fail;
+    }
+    if (prog->extflags & RXf_ANCH) {   /* Match at beg-of-str or after \n */
+       ml_anch = !( (prog->extflags & RXf_ANCH_SINGLE)
+                    || ( (prog->extflags & RXf_ANCH_BOL)
+                         && !multiline ) );    /* Check after \n? */
+
+       if (!ml_anch) {
+         if ( !(prog->extflags & RXf_ANCH_GPOS) /* Checked by the caller */
+               && !(prog->intflags & PREGf_IMPLICIT) /* not a real BOL */
+              /* SvCUR is not set on references: SvRV and SvPVX_const overlap */
+              && sv && !SvROK(sv)
+              && (strpos != strbeg)) {
+             DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Not at start...\n"));
+             goto fail;
+         }
+         if (prog->check_offset_min == prog->check_offset_max &&
+             !(prog->extflags & RXf_CANY_SEEN)) {
+           /* Substring at constant offset from beg-of-str... */
+           I32 slen;
+
+           s = HOP3c(strpos, prog->check_offset_min, strend);
+           
+           if (SvTAIL(check)) {
+               slen = SvCUR(check);    /* >= 1 */
+
+               if ( strend - s > slen || strend - s < slen - 1
+                    || (strend - s == slen && strend[-1] != '\n')) {
+                   DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "String too long...\n"));
+                   goto fail_finish;
+               }
+               /* Now should match s[0..slen-2] */
+               slen--;
+               if (slen && (*SvPVX_const(check) != *s
+                            || (slen > 1
+                                && memNE(SvPVX_const(check), s, slen)))) {
+                 report_neq:
+                   DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "String not equal...\n"));
+                   goto fail_finish;
+               }
+           }
+           else if (*SvPVX_const(check) != *s
+                    || ((slen = SvCUR(check)) > 1
+                        && memNE(SvPVX_const(check), s, slen)))
+               goto report_neq;
+           check_at = s;
+           goto success_at_start;
+         }
+       }
+       /* Match is anchored, but substr is not anchored wrt beg-of-str. */
+       s = strpos;
+       start_shift = prog->check_offset_min; /* okay to underestimate on CC */
+       end_shift = prog->check_end_shift;
+       
+       if (!ml_anch) {
+           const I32 end = prog->check_offset_max + CHR_SVLEN(check)
+                                        - (SvTAIL(check) != 0);
+           const I32 eshift = CHR_DIST((U8*)strend, (U8*)s) - end;
+
+           if (end_shift < eshift)
+               end_shift = eshift;
+       }
+    }
+    else {                             /* Can match at random position */
+       ml_anch = 0;
+       s = strpos;
+       start_shift = prog->check_offset_min;  /* okay to underestimate on CC */
+       end_shift = prog->check_end_shift;
+       
+       /* end shift should be non negative here */
+    }
+
+#ifdef QDEBUGGING      /* 7/99: reports of failure (with the older version) */
+    if (end_shift < 0)
+       Perl_croak(aTHX_ "panic: end_shift: %"IVdf" pattern:\n%s\n ",
+                  (IV)end_shift, RX_PRECOMP(prog));
+#endif
+
+  restart:
+    /* Find a possible match in the region s..strend by looking for
+       the "check" substring in the region corrected by start/end_shift. */
+    
+    {
+        I32 srch_start_shift = start_shift;
+        I32 srch_end_shift = end_shift;
+        if (srch_start_shift < 0 && strbeg - s > srch_start_shift) {
+           srch_end_shift -= ((strbeg - s) - srch_start_shift); 
+           srch_start_shift = strbeg - s;
+       }
+    DEBUG_OPTIMISE_MORE_r({
+        PerlIO_printf(Perl_debug_log, "Check offset min: %"IVdf" Start shift: %"IVdf" End shift %"IVdf" Real End Shift: %"IVdf"\n",
+            (IV)prog->check_offset_min,
+            (IV)srch_start_shift,
+            (IV)srch_end_shift, 
+            (IV)prog->check_end_shift);
+    });       
+        
+    if (flags & REXEC_SCREAM) {
+       I32 p = -1;                     /* Internal iterator of scream. */
+       I32 * const pp = data ? data->scream_pos : &p;
+
+       if (PL_screamfirst[BmRARE(check)] >= 0
+           || ( BmRARE(check) == '\n'
+                && (BmPREVIOUS(check) == SvCUR(check) - 1)
+                && SvTAIL(check) ))
+           s = screaminstr(sv, check,
+                           srch_start_shift + (s - strbeg), srch_end_shift, pp, 0);
+       else
+           goto fail_finish;
+       /* we may be pointing at the wrong string */
+       if (s && RXp_MATCH_COPIED(prog))
+           s = strbeg + (s - SvPVX_const(sv));
+       if (data)
+           *data->scream_olds = s;
+    }
+    else {
+        U8* start_point;
+        U8* end_point;
+        if (prog->extflags & RXf_CANY_SEEN) {
+            start_point= (U8*)(s + srch_start_shift);
+            end_point= (U8*)(strend - srch_end_shift);
+        } else {
+           start_point= HOP3(s, srch_start_shift, srch_start_shift < 0 ? strbeg : strend);
+            end_point= HOP3(strend, -srch_end_shift, strbeg);
+       }
+       DEBUG_OPTIMISE_MORE_r({
+            PerlIO_printf(Perl_debug_log, "fbm_instr len=%d str=<%.*s>\n", 
+                (int)(end_point - start_point),
+                (int)(end_point - start_point) > 20 ? 20 : (int)(end_point - start_point), 
+                start_point);
+        });
+
+       s = fbm_instr( start_point, end_point,
+                     check, multiline ? FBMrf_MULTILINE : 0);
+    }
+    }
+    /* Update the count-of-usability, remove useless subpatterns,
+       unshift s.  */
+
+    DEBUG_EXECUTE_r({
+        RE_PV_QUOTED_DECL(quoted, do_utf8, PERL_DEBUG_PAD_ZERO(0), 
+            SvPVX_const(check), RE_SV_DUMPLEN(check), 30);
+        PerlIO_printf(Perl_debug_log, "%s %s substr %s%s%s",
+                         (s ? "Found" : "Did not find"),
+           (check == (do_utf8 ? prog->anchored_utf8 : prog->anchored_substr) 
+               ? "anchored" : "floating"),
+           quoted,
+           RE_SV_TAIL(check),
+           (s ? " at offset " : "...\n") ); 
+    });
+
+    if (!s)
+       goto fail_finish;
+    /* Finish the diagnostic message */
+    DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%ld...\n", (long)(s - i_strpos)) );
+
+    /* XXX dmq: first branch is for positive lookbehind...
+       Our check string is offset from the beginning of the pattern.
+       So we need to do any stclass tests offset forward from that 
+       point. I think. :-(
+     */
+    
+        
+    
+    check_at=s;
+     
+
+    /* Got a candidate.  Check MBOL anchoring, and the *other* substr.
+       Start with the other substr.
+       XXXX no SCREAM optimization yet - and a very coarse implementation
+       XXXX /ttx+/ results in anchored="ttx", floating="x".  floating will
+               *always* match.  Probably should be marked during compile...
+       Probably it is right to do no SCREAM here...
+     */
+
+    if (do_utf8 ? (prog->float_utf8 && prog->anchored_utf8) 
+                : (prog->float_substr && prog->anchored_substr)) 
+    {
+       /* Take into account the "other" substring. */
+       /* XXXX May be hopelessly wrong for UTF... */
+       if (!other_last)
+           other_last = strpos;
+       if (check == (do_utf8 ? prog->float_utf8 : prog->float_substr)) {
+         do_other_anchored:
+           {
+               char * const last = HOP3c(s, -start_shift, strbeg);
+               char *last1, *last2;
+               char * const saved_s = s;
+               SV* must;
+
+               t = s - prog->check_offset_max;
+               if (s - strpos > prog->check_offset_max  /* signed-corrected t > strpos */
+                   && (!do_utf8
+                       || ((t = (char*)reghopmaybe3((U8*)s, -(prog->check_offset_max), (U8*)strpos))
+                           && t > strpos)))
+                   NOOP;
+               else
+                   t = strpos;
+               t = HOP3c(t, prog->anchored_offset, strend);
+               if (t < other_last)     /* These positions already checked */
+                   t = other_last;
+               last2 = last1 = HOP3c(strend, -prog->minlen, strbeg);
+               if (last < last1)
+                   last1 = last;
+                /* XXXX It is not documented what units *_offsets are in.  
+                   We assume bytes, but this is clearly wrong. 
+                   Meaning this code needs to be carefully reviewed for errors.
+                   dmq.
+                  */
+               /* On end-of-str: see comment below. */
+               must = do_utf8 ? prog->anchored_utf8 : prog->anchored_substr;
+               if (must == &PL_sv_undef) {
+                   s = (char*)NULL;
+                   DEBUG_r(must = prog->anchored_utf8);        /* for debug */
+               }
+               else
+                   s = fbm_instr(
+                       (unsigned char*)t,
+                       HOP3(HOP3(last1, prog->anchored_offset, strend)
+                               + SvCUR(must), -(SvTAIL(must)!=0), strbeg),
+                       must,
+                       multiline ? FBMrf_MULTILINE : 0
+                   );
+                DEBUG_EXECUTE_r({
+                    RE_PV_QUOTED_DECL(quoted, do_utf8, PERL_DEBUG_PAD_ZERO(0), 
+                        SvPVX_const(must), RE_SV_DUMPLEN(must), 30);
+                    PerlIO_printf(Perl_debug_log, "%s anchored substr %s%s",
+                       (s ? "Found" : "Contradicts"),
+                        quoted, RE_SV_TAIL(must));
+                });                
+               
+                           
+               if (!s) {
+                   if (last1 >= last2) {
+                       DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+                                               ", giving up...\n"));
+                       goto fail_finish;
+                   }
+                   DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+                       ", trying floating at offset %ld...\n",
+                       (long)(HOP3c(saved_s, 1, strend) - i_strpos)));
+                   other_last = HOP3c(last1, prog->anchored_offset+1, strend);
+                   s = HOP3c(last, 1, strend);
+                   goto restart;
+               }
+               else {
+                   DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, " at offset %ld...\n",
+                         (long)(s - i_strpos)));
+                   t = HOP3c(s, -prog->anchored_offset, strbeg);
+                   other_last = HOP3c(s, 1, strend);
+                   s = saved_s;
+                   if (t == strpos)
+                       goto try_at_start;
+                   goto try_at_offset;
+               }
+           }
+       }
+       else {          /* Take into account the floating substring. */
+           char *last, *last1;
+           char * const saved_s = s;
+           SV* must;
+
+           t = HOP3c(s, -start_shift, strbeg);
+           last1 = last =
+               HOP3c(strend, -prog->minlen + prog->float_min_offset, strbeg);
+           if (CHR_DIST((U8*)last, (U8*)t) > prog->float_max_offset)
+               last = HOP3c(t, prog->float_max_offset, strend);
+           s = HOP3c(t, prog->float_min_offset, strend);
+           if (s < other_last)
+               s = other_last;
+ /* XXXX It is not documented what units *_offsets are in.  Assume bytes.  */
+           must = do_utf8 ? prog->float_utf8 : prog->float_substr;
+           /* fbm_instr() takes into account exact value of end-of-str
+              if the check is SvTAIL(ed).  Since false positives are OK,
+              and end-of-str is not later than strend we are OK. */
+           if (must == &PL_sv_undef) {
+               s = (char*)NULL;
+               DEBUG_r(must = prog->float_utf8);       /* for debug message */
+           }
+           else
+               s = fbm_instr((unsigned char*)s,
+                             (unsigned char*)last + SvCUR(must)
+                                 - (SvTAIL(must)!=0),
+                             must, multiline ? FBMrf_MULTILINE : 0);
+           DEBUG_EXECUTE_r({
+               RE_PV_QUOTED_DECL(quoted, do_utf8, PERL_DEBUG_PAD_ZERO(0), 
+                   SvPVX_const(must), RE_SV_DUMPLEN(must), 30);
+               PerlIO_printf(Perl_debug_log, "%s floating substr %s%s",
+                   (s ? "Found" : "Contradicts"),
+                   quoted, RE_SV_TAIL(must));
+            });
+           if (!s) {
+               if (last1 == last) {
+                   DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+                                           ", giving up...\n"));
+                   goto fail_finish;
+               }
+               DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+                   ", trying anchored starting at offset %ld...\n",
+                   (long)(saved_s + 1 - i_strpos)));
+               other_last = last;
+               s = HOP3c(t, 1, strend);
+               goto restart;
+           }
+           else {
+               DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, " at offset %ld...\n",
+                     (long)(s - i_strpos)));
+               other_last = s; /* Fix this later. --Hugo */
+               s = saved_s;
+               if (t == strpos)
+                   goto try_at_start;
+               goto try_at_offset;
+           }
+       }
+    }
+
+    
+    t= (char*)HOP3( s, -prog->check_offset_max, (prog->check_offset_max<0) ? strend : strpos);
+        
+    DEBUG_OPTIMISE_MORE_r(
+        PerlIO_printf(Perl_debug_log, 
+            "Check offset min:%"IVdf" max:%"IVdf" S:%"IVdf" t:%"IVdf" D:%"IVdf" end:%"IVdf"\n",
+            (IV)prog->check_offset_min,
+            (IV)prog->check_offset_max,
+            (IV)(s-strpos),
+            (IV)(t-strpos),
+            (IV)(t-s),
+            (IV)(strend-strpos)
+        )
+    );
+
+    if (s - strpos > prog->check_offset_max  /* signed-corrected t > strpos */
+        && (!do_utf8
+           || ((t = (char*)reghopmaybe3((U8*)s, -prog->check_offset_max, (U8*) ((prog->check_offset_max<0) ? strend : strpos)))
+                && t > strpos))) 
+    {
+       /* Fixed substring is found far enough so that the match
+          cannot start at strpos. */
+      try_at_offset:
+       if (ml_anch && t[-1] != '\n') {
+           /* Eventually fbm_*() should handle this, but often
+              anchored_offset is not 0, so this check will not be wasted. */
+           /* XXXX In the code below we prefer to look for "^" even in
+              presence of anchored substrings.  And we search even
+              beyond the found float position.  These pessimizations
+              are historical artefacts only.  */
+         find_anchor:
+           while (t < strend - prog->minlen) {
+               if (*t == '\n') {
+                   if (t < check_at - prog->check_offset_min) {
+                       if (do_utf8 ? prog->anchored_utf8 : prog->anchored_substr) {
+                           /* Since we moved from the found position,
+                              we definitely contradict the found anchored
+                              substr.  Due to the above check we do not
+                              contradict "check" substr.
+                              Thus we can arrive here only if check substr
+                              is float.  Redo checking for "other"=="fixed".
+                            */
+                           strpos = t + 1;                     
+                           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Found /%s^%s/m at offset %ld, rescanning for anchored from offset %ld...\n",
+                               PL_colors[0], PL_colors[1], (long)(strpos - i_strpos), (long)(strpos - i_strpos + prog->anchored_offset)));
+                           goto do_other_anchored;
+                       }
+                       /* We don't contradict the found floating substring. */
+                       /* XXXX Why not check for STCLASS? */
+                       s = t + 1;
+                       DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Found /%s^%s/m at offset %ld...\n",
+                           PL_colors[0], PL_colors[1], (long)(s - i_strpos)));
+                       goto set_useful;
+                   }
+                   /* Position contradicts check-string */
+                   /* XXXX probably better to look for check-string
+                      than for "\n", so one should lower the limit for t? */
+                   DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Found /%s^%s/m, restarting lookup for check-string at offset %ld...\n",
+                       PL_colors[0], PL_colors[1], (long)(t + 1 - i_strpos)));
+                   other_last = strpos = s = t + 1;
+                   goto restart;
+               }
+               t++;
+           }
+           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Did not find /%s^%s/m...\n",
+                       PL_colors[0], PL_colors[1]));
+           goto fail_finish;
+       }
+       else {
+           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Starting position does not contradict /%s^%s/m...\n",
+                       PL_colors[0], PL_colors[1]));
+       }
+       s = t;
+      set_useful:
+       ++BmUSEFUL(do_utf8 ? prog->check_utf8 : prog->check_substr);    /* hooray/5 */
+    }
+    else {
+       /* The found string does not prohibit matching at strpos,
+          - no optimization of calling REx engine can be performed,
+          unless it was an MBOL and we are not after MBOL,
+          or a future STCLASS check will fail this. */
+      try_at_start:
+       /* Even in this situation we may use MBOL flag if strpos is offset
+          wrt the start of the string. */
+       if (ml_anch && sv && !SvROK(sv) /* See prev comment on SvROK */
+           && (strpos != strbeg) && strpos[-1] != '\n'
+           /* May be due to an implicit anchor of m{.*foo}  */
+           && !(prog->intflags & PREGf_IMPLICIT))
+       {
+           t = strpos;
+           goto find_anchor;
+       }
+       DEBUG_EXECUTE_r( if (ml_anch)
+           PerlIO_printf(Perl_debug_log, "Position at offset %ld does not contradict /%s^%s/m...\n",
+                         (long)(strpos - i_strpos), PL_colors[0], PL_colors[1]);
+       );
+      success_at_start:
+       if (!(prog->intflags & PREGf_NAUGHTY)   /* XXXX If strpos moved? */
+           && (do_utf8 ? (
+               prog->check_utf8                /* Could be deleted already */
+               && --BmUSEFUL(prog->check_utf8) < 0
+               && (prog->check_utf8 == prog->float_utf8)
+           ) : (
+               prog->check_substr              /* Could be deleted already */
+               && --BmUSEFUL(prog->check_substr) < 0
+               && (prog->check_substr == prog->float_substr)
+           )))
+       {
+           /* If flags & SOMETHING - do not do it many times on the same match */
+           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "... Disabling check substring...\n"));
+           /* XXX Does the destruction order has to change with do_utf8? */
+           SvREFCNT_dec(do_utf8 ? prog->check_utf8 : prog->check_substr);
+           SvREFCNT_dec(do_utf8 ? prog->check_substr : prog->check_utf8);
+           prog->check_substr = prog->check_utf8 = NULL;       /* disable */
+           prog->float_substr = prog->float_utf8 = NULL;       /* clear */
+           check = NULL;                       /* abort */
+           s = strpos;
+           /* XXXX This is a remnant of the old implementation.  It
+                   looks wasteful, since now INTUIT can use many
+                   other heuristics. */
+           prog->extflags &= ~RXf_USE_INTUIT;
+       }
+       else
+           s = strpos;
+    }
+
+    /* Last resort... */
+    /* XXXX BmUSEFUL already changed, maybe multiple change is meaningful... */
+    /* trie stclasses are too expensive to use here, we are better off to
+       leave it to regmatch itself */
+    if (progi->regstclass && PL_regkind[OP(progi->regstclass)]!=TRIE) {
+       /* minlen == 0 is possible if regstclass is \b or \B,
+          and the fixed substr is ''$.
+          Since minlen is already taken into account, s+1 is before strend;
+          accidentally, minlen >= 1 guaranties no false positives at s + 1
+          even for \b or \B.  But (minlen? 1 : 0) below assumes that
+          regstclass does not come from lookahead...  */
+       /* If regstclass takes bytelength more than 1: If charlength==1, OK.
+          This leaves EXACTF only, which is dealt with in find_byclass().  */
+        const U8* const str = (U8*)STRING(progi->regstclass);
+        const int cl_l = (PL_regkind[OP(progi->regstclass)] == EXACT
+                   ? CHR_DIST(str+STR_LEN(progi->regstclass), str)
+                   : 1);
+       char * endpos;
+       if (prog->anchored_substr || prog->anchored_utf8 || ml_anch)
+            endpos= HOP3c(s, (prog->minlen ? cl_l : 0), strend);
+        else if (prog->float_substr || prog->float_utf8)
+           endpos= HOP3c(HOP3c(check_at, -start_shift, strbeg), cl_l, strend);
+        else 
+            endpos= strend;
+                   
+        DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "start_shift: %"IVdf" check_at: %"IVdf" s: %"IVdf" endpos: %"IVdf"\n",
+                                     (IV)start_shift, (IV)(check_at - strbeg), (IV)(s - strbeg), (IV)(endpos - strbeg)));
+       
+       t = s;
+        s = find_byclass(prog, progi->regstclass, s, endpos, NULL);
+       if (!s) {
+#ifdef DEBUGGING
+           const char *what = NULL;
+#endif
+           if (endpos == strend) {
+               DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
+                               "Could not match STCLASS...\n") );
+               goto fail;
+           }
+           DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
+                                  "This position contradicts STCLASS...\n") );
+           if ((prog->extflags & RXf_ANCH) && !ml_anch)
+               goto fail;
+           /* Contradict one of substrings */
+           if (prog->anchored_substr || prog->anchored_utf8) {
+               if ((do_utf8 ? prog->anchored_utf8 : prog->anchored_substr) == check) {
+                   DEBUG_EXECUTE_r( what = "anchored" );
+                 hop_and_restart:
+                   s = HOP3c(t, 1, strend);
+                   if (s + start_shift + end_shift > strend) {
+                       /* XXXX Should be taken into account earlier? */
+                       DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
+                                              "Could not match STCLASS...\n") );
+                       goto fail;
+                   }
+                   if (!check)
+                       goto giveup;
+                   DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
+                               "Looking for %s substr starting at offset %ld...\n",
+                                what, (long)(s + start_shift - i_strpos)) );
+                   goto restart;
+               }
+               /* Have both, check_string is floating */
+               if (t + start_shift >= check_at) /* Contradicts floating=check */
+                   goto retry_floating_check;
+               /* Recheck anchored substring, but not floating... */
+               s = check_at;
+               if (!check)
+                   goto giveup;
+               DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
+                         "Looking for anchored substr starting at offset %ld...\n",
+                         (long)(other_last - i_strpos)) );
+               goto do_other_anchored;
+           }
+           /* Another way we could have checked stclass at the
+               current position only: */
+           if (ml_anch) {
+               s = t = t + 1;
+               if (!check)
+                   goto giveup;
+               DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
+                         "Looking for /%s^%s/m starting at offset %ld...\n",
+                         PL_colors[0], PL_colors[1], (long)(t - i_strpos)) );
+               goto try_at_offset;
+           }
+           if (!(do_utf8 ? prog->float_utf8 : prog->float_substr))     /* Could have been deleted */
+               goto fail;
+           /* Check is floating subtring. */
+         retry_floating_check:
+           t = check_at - start_shift;
+           DEBUG_EXECUTE_r( what = "floating" );
+           goto hop_and_restart;
+       }
+       if (t != s) {
+            DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+                       "By STCLASS: moving %ld --> %ld\n",
+                                  (long)(t - i_strpos), (long)(s - i_strpos))
+                   );
+        }
+        else {
+            DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+                                  "Does not contradict STCLASS...\n"); 
+                   );
+        }
+    }
+  giveup:
+    DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%s%s:%s match at offset %ld\n",
+                         PL_colors[4], (check ? "Guessed" : "Giving up"),
+                         PL_colors[5], (long)(s - i_strpos)) );
+    return s;
+
+  fail_finish:                         /* Substring not found */
+    if (prog->check_substr || prog->check_utf8)                /* could be removed already */
+       BmUSEFUL(do_utf8 ? prog->check_utf8 : prog->check_substr) += 5; /* hooray */
+  fail:
+    DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%sMatch rejected by optimizer%s\n",
+                         PL_colors[4], PL_colors[5]));
+    return NULL;
+}
+
+#define DECL_TRIE_TYPE(scan) \
+    const enum { trie_plain, trie_utf8, trie_utf8_fold, trie_latin_utf8_fold } \
+                   trie_type = (scan->flags != EXACT) \
+                             ? (do_utf8 ? trie_utf8_fold : (UTF ? trie_latin_utf8_fold : trie_plain)) \
+                              : (do_utf8 ? trie_utf8 : trie_plain)
+
+#define REXEC_TRIE_READ_CHAR(trie_type, trie, widecharmap, uc, uscan, len,  \
+uvc, charid, foldlen, foldbuf, uniflags) STMT_START {                       \
+    switch (trie_type) {                                                    \
+    case trie_utf8_fold:                                                    \
+       if ( foldlen>0 ) {                                                  \
+           uvc = utf8n_to_uvuni( uscan, UTF8_MAXLEN, &len, uniflags ); \
+           foldlen -= len;                                                 \
+           uscan += len;                                                   \
+           len=0;                                                          \
+       } else {                                                            \
+           uvc = utf8n_to_uvuni( (U8*)uc, UTF8_MAXLEN, &len, uniflags ); \
+           uvc = to_uni_fold( uvc, foldbuf, &foldlen );                    \
+           foldlen -= UNISKIP( uvc );                                      \
+           uscan = foldbuf + UNISKIP( uvc );                               \
+       }                                                                   \
+       break;                                                              \
+    case trie_latin_utf8_fold:                                              \
+       if ( foldlen>0 ) {                                                  \
+           uvc = utf8n_to_uvuni( uscan, UTF8_MAXLEN, &len, uniflags );     \
+           foldlen -= len;                                                 \
+           uscan += len;                                                   \
+           len=0;                                                          \
+       } else {                                                            \
+           len = 1;                                                        \
+           uvc = to_uni_fold( *(U8*)uc, foldbuf, &foldlen );               \
+           foldlen -= UNISKIP( uvc );                                      \
+           uscan = foldbuf + UNISKIP( uvc );                               \
+       }                                                                   \
+       break;                                                              \
+    case trie_utf8:                                                         \
+       uvc = utf8n_to_uvuni( (U8*)uc, UTF8_MAXLEN, &len, uniflags );       \
+       break;                                                              \
+    case trie_plain:                                                        \
+       uvc = (UV)*uc;                                                      \
+       len = 1;                                                            \
+    }                                                                       \
+    if (uvc < 256) {                                                        \
+       charid = trie->charmap[ uvc ];                                      \
+    }                                                                       \
+    else {                                                                  \
+       charid = 0;                                                         \
+       if (widecharmap) {                                                  \
+           SV** const svpp = hv_fetch(widecharmap,                         \
+                       (char*)&uvc, sizeof(UV), 0);                        \
+           if (svpp)                                                       \
+               charid = (U16)SvIV(*svpp);                                  \
+       }                                                                   \
+    }                                                                       \
+} STMT_END
+
+#define REXEC_FBC_EXACTISH_CHECK(CoNd)                 \
+{                                                      \
+    char *my_strend= (char *)strend;                   \
+    if ( (CoNd)                                        \
+        && (ln == len ||                              \
+            !ibcmp_utf8(s, &my_strend, 0,  do_utf8,   \
+                       m, NULL, ln, (bool)UTF))       \
+        && (!reginfo || regtry(reginfo, &s)) )        \
+       goto got_it;                                   \
+    else {                                             \
+        U8 foldbuf[UTF8_MAXBYTES_CASE+1];             \
+        uvchr_to_utf8(tmpbuf, c);                     \
+        f = to_utf8_fold(tmpbuf, foldbuf, &foldlen);  \
+        if ( f != c                                   \
+             && (f == c1 || f == c2)                  \
+             && (ln == len ||                         \
+               !ibcmp_utf8(s, &my_strend, 0,  do_utf8,\
+                             m, NULL, ln, (bool)UTF)) \
+             && (!reginfo || regtry(reginfo, &s)) )   \
+             goto got_it;                             \
+    }                                                  \
+}                                                      \
+s += len
+
+#define REXEC_FBC_EXACTISH_SCAN(CoNd)                     \
+STMT_START {                                              \
+    while (s <= e) {                                      \
+       if ( (CoNd)                                       \
+            && (ln == 1 || !(OP(c) == EXACTF             \
+                             ? ibcmp(s, m, ln)           \
+                             : ibcmp_locale(s, m, ln)))  \
+            && (!reginfo || regtry(reginfo, &s)) )        \
+           goto got_it;                                  \
+       s++;                                              \
+    }                                                     \
+} STMT_END
+
+#define REXEC_FBC_UTF8_SCAN(CoDe)                     \
+STMT_START {                                          \
+    while (s + (uskip = UTF8SKIP(s)) <= strend) {     \
+       CoDe                                          \
+       s += uskip;                                   \
+    }                                                 \
+} STMT_END
+
+#define REXEC_FBC_SCAN(CoDe)                          \
+STMT_START {                                          \
+    while (s < strend) {                              \
+       CoDe                                          \
+       s++;                                          \
+    }                                                 \
+} STMT_END
+
+#define REXEC_FBC_UTF8_CLASS_SCAN(CoNd)               \
+REXEC_FBC_UTF8_SCAN(                                  \
+    if (CoNd) {                                       \
+       if (tmp && (!reginfo || regtry(reginfo, &s)))  \
+           goto got_it;                              \
+       else                                          \
+           tmp = doevery;                            \
+    }                                                 \
+    else                                              \
+       tmp = 1;                                      \
+)
+
+#define REXEC_FBC_CLASS_SCAN(CoNd)                    \
+REXEC_FBC_SCAN(                                       \
+    if (CoNd) {                                       \
+       if (tmp && (!reginfo || regtry(reginfo, &s)))  \
+           goto got_it;                              \
+       else                                          \
+           tmp = doevery;                            \
+    }                                                 \
+    else                                              \
+       tmp = 1;                                      \
+)
+
+#define REXEC_FBC_TRYIT               \
+if ((!reginfo || regtry(reginfo, &s))) \
+    goto got_it
+
+#define REXEC_FBC_CSCAN(CoNdUtF8,CoNd)                         \
+    if (do_utf8) {                                             \
+       REXEC_FBC_UTF8_CLASS_SCAN(CoNdUtF8);                   \
+    }                                                          \
+    else {                                                     \
+       REXEC_FBC_CLASS_SCAN(CoNd);                            \
+    }                                                          \
+    break
+    
+#define REXEC_FBC_CSCAN_PRELOAD(UtFpReLoAd,CoNdUtF8,CoNd)      \
+    if (do_utf8) {                                             \
+       UtFpReLoAd;                                            \
+       REXEC_FBC_UTF8_CLASS_SCAN(CoNdUtF8);                   \
+    }                                                          \
+    else {                                                     \
+       REXEC_FBC_CLASS_SCAN(CoNd);                            \
+    }                                                          \
+    break
+
+#define REXEC_FBC_CSCAN_TAINT(CoNdUtF8,CoNd)                   \
+    PL_reg_flags |= RF_tainted;                                \
+    if (do_utf8) {                                             \
+       REXEC_FBC_UTF8_CLASS_SCAN(CoNdUtF8);                   \
+    }                                                          \
+    else {                                                     \
+       REXEC_FBC_CLASS_SCAN(CoNd);                            \
+    }                                                          \
+    break
+
+#define DUMP_EXEC_POS(li,s,doutf8) \
+    dump_exec_pos(li,s,(PL_regeol),(PL_bostr),(PL_reg_starttry),doutf8)
+
+/* We know what class REx starts with.  Try to find this position... */
+/* if reginfo is NULL, its a dryrun */
+/* annoyingly all the vars in this routine have different names from their counterparts
+   in regmatch. /grrr */
+
+STATIC char *
+S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s, 
+    const char *strend, regmatch_info *reginfo)
+{
+       dVAR;
+       const I32 doevery = (prog->intflags & PREGf_SKIP) == 0;
+       char *m;
+       STRLEN ln;
+       STRLEN lnc;
+       register STRLEN uskip;
+       unsigned int c1;
+       unsigned int c2;
+       char *e;
+       register I32 tmp = 1;   /* Scratch variable? */
+       register const bool do_utf8 = PL_reg_match_utf8;
+        RXi_GET_DECL(prog,progi);
+
+       PERL_ARGS_ASSERT_FIND_BYCLASS;
+        
+       /* We know what class it must start with. */
+       switch (OP(c)) {
+       case ANYOF:
+           if (do_utf8) {
+                REXEC_FBC_UTF8_CLASS_SCAN((ANYOF_FLAGS(c) & ANYOF_UNICODE) ||
+                         !UTF8_IS_INVARIANT((U8)s[0]) ?
+                         reginclass(prog, c, (U8*)s, 0, do_utf8) :
+                         REGINCLASS(prog, c, (U8*)s));
+           }
+           else {
+                while (s < strend) {
+                     STRLEN skip = 1;
+
+                     if (REGINCLASS(prog, c, (U8*)s) ||
+                         (ANYOF_FOLD_SHARP_S(c, s, strend) &&
+                          /* The assignment of 2 is intentional:
+                           * for the folded sharp s, the skip is 2. */
+                          (skip = SHARP_S_SKIP))) {
+                          if (tmp && (!reginfo || regtry(reginfo, &s)))
+                               goto got_it;
+                          else
+                               tmp = doevery;
+                     }
+                     else 
+                          tmp = 1;
+                     s += skip;
+                }
+           }
+           break;
+       case CANY:
+           REXEC_FBC_SCAN(
+               if (tmp && (!reginfo || regtry(reginfo, &s)))
+                   goto got_it;
+               else
+                   tmp = doevery;
+           );
+           break;
+       case EXACTF:
+           m   = STRING(c);
+           ln  = STR_LEN(c);   /* length to match in octets/bytes */
+           lnc = (I32) ln;     /* length to match in characters */
+           if (UTF) {
+               STRLEN ulen1, ulen2;
+               U8 *sm = (U8 *) m;
+               U8 tmpbuf1[UTF8_MAXBYTES_CASE+1];
+               U8 tmpbuf2[UTF8_MAXBYTES_CASE+1];
+               /* used by commented-out code below */
+               /*const U32 uniflags = UTF8_ALLOW_DEFAULT;*/
+               
+                /* XXX: Since the node will be case folded at compile
+                   time this logic is a little odd, although im not 
+                   sure that its actually wrong. --dmq */
+                   
+               c1 = to_utf8_lower((U8*)m, tmpbuf1, &ulen1);
+               c2 = to_utf8_upper((U8*)m, tmpbuf2, &ulen2);
+
+               /* XXX: This is kinda strange. to_utf8_XYZ returns the 
+                   codepoint of the first character in the converted
+                   form, yet originally we did the extra step. 
+                   No tests fail by commenting this code out however
+                   so Ive left it out. -- dmq.
+                   
+               c1 = utf8n_to_uvchr(tmpbuf1, UTF8_MAXBYTES_CASE, 
+                                   0, uniflags);
+               c2 = utf8n_to_uvchr(tmpbuf2, UTF8_MAXBYTES_CASE,
+                                   0, uniflags);
+                */
+                
+               lnc = 0;
+               while (sm < ((U8 *) m + ln)) {
+                   lnc++;
+                   sm += UTF8SKIP(sm);
+               }
+           }
+           else {
+               c1 = *(U8*)m;
+               c2 = PL_fold[c1];
+           }
+           goto do_exactf;
+       case EXACTFL:
+           m   = STRING(c);
+           ln  = STR_LEN(c);
+           lnc = (I32) ln;
+           c1 = *(U8*)m;
+           c2 = PL_fold_locale[c1];
+         do_exactf:
+           e = HOP3c(strend, -((I32)lnc), s);
+
+           if (!reginfo && e < s)
+               e = s;                  /* Due to minlen logic of intuit() */
+
+           /* The idea in the EXACTF* cases is to first find the
+            * first character of the EXACTF* node and then, if
+            * necessary, case-insensitively compare the full
+            * text of the node.  The c1 and c2 are the first
+            * characters (though in Unicode it gets a bit
+            * more complicated because there are more cases
+            * than just upper and lower: one needs to use
+            * the so-called folding case for case-insensitive
+            * matching (called "loose matching" in Unicode).
+            * ibcmp_utf8() will do just that. */
+
+           if (do_utf8 || UTF) {
+               UV c, f;
+               U8 tmpbuf [UTF8_MAXBYTES+1];
+               STRLEN len = 1;
+               STRLEN foldlen;
+               const U32 uniflags = UTF8_ALLOW_DEFAULT;
+               if (c1 == c2) {
+                   /* Upper and lower of 1st char are equal -
+                    * probably not a "letter". */
+                   while (s <= e) {
+                       if (do_utf8) {
+                           c = utf8n_to_uvchr((U8*)s, UTF8_MAXBYTES, &len,
+                                          uniflags);
+                        } else {
+                            c = *((U8*)s);
+                        }                                        
+                       REXEC_FBC_EXACTISH_CHECK(c == c1);
+                   }
+               }
+               else {
+                   while (s <= e) {
+                       if (do_utf8) {
+                           c = utf8n_to_uvchr((U8*)s, UTF8_MAXBYTES, &len,
+                                          uniflags);
+                        } else {
+                            c = *((U8*)s);
+                        }
+
+                       /* Handle some of the three Greek sigmas cases.
+                        * Note that not all the possible combinations
+                        * are handled here: some of them are handled
+                        * by the standard folding rules, and some of
+                        * them (the character class or ANYOF cases)
+                        * are handled during compiletime in
+                        * regexec.c:S_regclass(). */
+                       if (c == (UV)UNICODE_GREEK_CAPITAL_LETTER_SIGMA ||
+                           c == (UV)UNICODE_GREEK_SMALL_LETTER_FINAL_SIGMA)
+                           c = (UV)UNICODE_GREEK_SMALL_LETTER_SIGMA;
+
+                       REXEC_FBC_EXACTISH_CHECK(c == c1 || c == c2);
+                   }
+               }
+           }
+           else {
+               /* Neither pattern nor string are UTF8 */
+               if (c1 == c2)
+                   REXEC_FBC_EXACTISH_SCAN(*(U8*)s == c1);
+               else
+                   REXEC_FBC_EXACTISH_SCAN(*(U8*)s == c1 || *(U8*)s == c2);
+           }
+           break;
+       case BOUNDL:
+           PL_reg_flags |= RF_tainted;
+           /* FALL THROUGH */
+       case BOUND:
+           if (do_utf8) {
+               if (s == PL_bostr)
+                   tmp = '\n';
+               else {
+                   U8 * const r = reghop3((U8*)s, -1, (U8*)PL_bostr);
+                   tmp = utf8n_to_uvchr(r, UTF8SKIP(r), 0, UTF8_ALLOW_DEFAULT);
+               }
+               tmp = ((OP(c) == BOUND ?
+                       isALNUM_uni(tmp) : isALNUM_LC_uvchr(UNI_TO_NATIVE(tmp))) != 0);
+               LOAD_UTF8_CHARCLASS_ALNUM();
+               REXEC_FBC_UTF8_SCAN(
+                   if (tmp == !(OP(c) == BOUND ?
+                                (bool)swash_fetch(PL_utf8_alnum, (U8*)s, do_utf8) :
+                                isALNUM_LC_utf8((U8*)s)))
+                   {
+                       tmp = !tmp;
+                       REXEC_FBC_TRYIT;
+               }
+               );
+           }
+           else {
+               tmp = (s != PL_bostr) ? UCHARAT(s - 1) : '\n';
+               tmp = ((OP(c) == BOUND ? isALNUM(tmp) : isALNUM_LC(tmp)) != 0);
+               REXEC_FBC_SCAN(
+                   if (tmp ==
+                       !(OP(c) == BOUND ? isALNUM(*s) : isALNUM_LC(*s))) {
+                       tmp = !tmp;
+                       REXEC_FBC_TRYIT;
+               }
+               );
+           }
+           if ((!prog->minlen && tmp) && (!reginfo || regtry(reginfo, &s)))
+               goto got_it;
+           break;
+       case NBOUNDL:
+           PL_reg_flags |= RF_tainted;
+           /* FALL THROUGH */
+       case NBOUND:
+           if (do_utf8) {
+               if (s == PL_bostr)
+                   tmp = '\n';
+               else {
+                   U8 * const r = reghop3((U8*)s, -1, (U8*)PL_bostr);
+                   tmp = utf8n_to_uvchr(r, UTF8SKIP(r), 0, UTF8_ALLOW_DEFAULT);
+               }
+               tmp = ((OP(c) == NBOUND ?
+                       isALNUM_uni(tmp) : isALNUM_LC_uvchr(UNI_TO_NATIVE(tmp))) != 0);
+               LOAD_UTF8_CHARCLASS_ALNUM();
+               REXEC_FBC_UTF8_SCAN(
+                   if (tmp == !(OP(c) == NBOUND ?
+                                (bool)swash_fetch(PL_utf8_alnum, (U8*)s, do_utf8) :
+                                isALNUM_LC_utf8((U8*)s)))
+                       tmp = !tmp;
+                   else REXEC_FBC_TRYIT;
+               );
+           }
+           else {
+               tmp = (s != PL_bostr) ? UCHARAT(s - 1) : '\n';
+               tmp = ((OP(c) == NBOUND ?
+                       isALNUM(tmp) : isALNUM_LC(tmp)) != 0);
+               REXEC_FBC_SCAN(
+                   if (tmp ==
+                       !(OP(c) == NBOUND ? isALNUM(*s) : isALNUM_LC(*s)))
+                       tmp = !tmp;
+                   else REXEC_FBC_TRYIT;
+               );
+           }
+           if ((!prog->minlen && !tmp) && (!reginfo || regtry(reginfo, &s)))
+               goto got_it;
+           break;
+       case ALNUM:
+           REXEC_FBC_CSCAN_PRELOAD(
+               LOAD_UTF8_CHARCLASS_PERL_WORD(),
+               swash_fetch(RE_utf8_perl_word, (U8*)s, do_utf8),
+               isALNUM(*s)
+           );
+       case ALNUML:
+           REXEC_FBC_CSCAN_TAINT(
+               isALNUM_LC_utf8((U8*)s),
+               isALNUM_LC(*s)
+           );
+       case NALNUM:
+           REXEC_FBC_CSCAN_PRELOAD(
+               LOAD_UTF8_CHARCLASS_PERL_WORD(),
+               !swash_fetch(RE_utf8_perl_word, (U8*)s, do_utf8),
+               !isALNUM(*s)
+           );
+       case NALNUML:
+           REXEC_FBC_CSCAN_TAINT(
+               !isALNUM_LC_utf8((U8*)s),
+               !isALNUM_LC(*s)
+           );
+       case SPACE:
+           REXEC_FBC_CSCAN_PRELOAD(
+               LOAD_UTF8_CHARCLASS_PERL_SPACE(),
+               *s == ' ' || swash_fetch(RE_utf8_perl_space,(U8*)s, do_utf8),
+               isSPACE(*s)
+           );
+       case SPACEL:
+           REXEC_FBC_CSCAN_TAINT(
+               *s == ' ' || isSPACE_LC_utf8((U8*)s),
+               isSPACE_LC(*s)
+           );
+       case NSPACE:
+           REXEC_FBC_CSCAN_PRELOAD(
+               LOAD_UTF8_CHARCLASS_PERL_SPACE(),
+               !(*s == ' ' || swash_fetch(RE_utf8_perl_space,(U8*)s, do_utf8)),
+               !isSPACE(*s)
+           );
+       case NSPACEL:
+           REXEC_FBC_CSCAN_TAINT(
+               !(*s == ' ' || isSPACE_LC_utf8((U8*)s)),
+               !isSPACE_LC(*s)
+           );
+       case DIGIT:
+           REXEC_FBC_CSCAN_PRELOAD(
+               LOAD_UTF8_CHARCLASS_POSIX_DIGIT(),
+               swash_fetch(RE_utf8_posix_digit,(U8*)s, do_utf8),
+               isDIGIT(*s)
+           );
+       case DIGITL:
+           REXEC_FBC_CSCAN_TAINT(
+               isDIGIT_LC_utf8((U8*)s),
+               isDIGIT_LC(*s)
+           );
+       case NDIGIT:
+           REXEC_FBC_CSCAN_PRELOAD(
+               LOAD_UTF8_CHARCLASS_POSIX_DIGIT(),
+               !swash_fetch(RE_utf8_posix_digit,(U8*)s, do_utf8),
+               !isDIGIT(*s)
+           );
+       case NDIGITL:
+           REXEC_FBC_CSCAN_TAINT(
+               !isDIGIT_LC_utf8((U8*)s),
+               !isDIGIT_LC(*s)
+           );
+       case LNBREAK:
+           REXEC_FBC_CSCAN(
+               is_LNBREAK_utf8(s),
+               is_LNBREAK_latin1(s)
+           );
+       case VERTWS:
+           REXEC_FBC_CSCAN(
+               is_VERTWS_utf8(s),
+               is_VERTWS_latin1(s)
+           );
+       case NVERTWS:
+           REXEC_FBC_CSCAN(
+               !is_VERTWS_utf8(s),
+               !is_VERTWS_latin1(s)
+           );
+       case HORIZWS:
+           REXEC_FBC_CSCAN(
+               is_HORIZWS_utf8(s),
+               is_HORIZWS_latin1(s)
+           );
+       case NHORIZWS:
+           REXEC_FBC_CSCAN(
+               !is_HORIZWS_utf8(s),
+               !is_HORIZWS_latin1(s)
+           );      
+       case AHOCORASICKC:
+       case AHOCORASICK: 
+           {
+               DECL_TRIE_TYPE(c);
+                /* what trie are we using right now */
+               reg_ac_data *aho
+                   = (reg_ac_data*)progi->data->data[ ARG( c ) ];
+               reg_trie_data *trie
+                   = (reg_trie_data*)progi->data->data[ aho->trie ];
+               HV *widecharmap = MUTABLE_HV(progi->data->data[ aho->trie + 1 ]);
+
+               const char *last_start = strend - trie->minlen;
+#ifdef DEBUGGING
+               const char *real_start = s;
+#endif
+               STRLEN maxlen = trie->maxlen;
+               SV *sv_points;
+               U8 **points; /* map of where we were in the input string
+                               when reading a given char. For ASCII this
+                               is unnecessary overhead as the relationship
+                               is always 1:1, but for Unicode, especially
+                               case folded Unicode this is not true. */
+               U8 foldbuf[ UTF8_MAXBYTES_CASE + 1 ];
+               U8 *bitmap=NULL;
+
+
+                GET_RE_DEBUG_FLAGS_DECL;
+
+                /* We can't just allocate points here. We need to wrap it in
+                 * an SV so it gets freed properly if there is a croak while
+                 * running the match */
+                ENTER;
+               SAVETMPS;
+                sv_points=newSV(maxlen * sizeof(U8 *));
+                SvCUR_set(sv_points,
+                    maxlen * sizeof(U8 *));
+                SvPOK_on(sv_points);
+                sv_2mortal(sv_points);
+                points=(U8**)SvPV_nolen(sv_points );
+                if ( trie_type != trie_utf8_fold 
+                     && (trie->bitmap || OP(c)==AHOCORASICKC) ) 
+                {
+                    if (trie->bitmap) 
+                        bitmap=(U8*)trie->bitmap;
+                    else
+                        bitmap=(U8*)ANYOF_BITMAP(c);
+                }
+                /* this is the Aho-Corasick algorithm modified a touch
+                   to include special handling for long "unknown char" 
+                   sequences. The basic idea being that we use AC as long
+                   as we are dealing with a possible matching char, when
+                   we encounter an unknown char (and we have not encountered
+                   an accepting state) we scan forward until we find a legal 
+                   starting char. 
+                   AC matching is basically that of trie matching, except
+                   that when we encounter a failing transition, we fall back
+                   to the current states "fail state", and try the current char 
+                   again, a process we repeat until we reach the root state, 
+                   state 1, or a legal transition. If we fail on the root state 
+                   then we can either terminate if we have reached an accepting 
+                   state previously, or restart the entire process from the beginning 
+                   if we have not.
+
+                 */
+                while (s <= last_start) {
+                    const U32 uniflags = UTF8_ALLOW_DEFAULT;
+                    U8 *uc = (U8*)s;
+                    U16 charid = 0;
+                    U32 base = 1;
+                    U32 state = 1;
+                    UV uvc = 0;
+                    STRLEN len = 0;
+                    STRLEN foldlen = 0;
+                    U8 *uscan = (U8*)NULL;
+                    U8 *leftmost = NULL;
+#ifdef DEBUGGING                    
+                    U32 accepted_word= 0;
+#endif
+                    U32 pointpos = 0;
+
+                    while ( state && uc <= (U8*)strend ) {
+                        int failed=0;
+                        U32 word = aho->states[ state ].wordnum;
+
+                        if( state==1 ) {
+                            if ( bitmap ) {
+                                DEBUG_TRIE_EXECUTE_r(
+                                    if ( uc <= (U8*)last_start && !BITMAP_TEST(bitmap,*uc) ) {
+                                        dump_exec_pos( (char *)uc, c, strend, real_start, 
+                                            (char *)uc, do_utf8 );
+                                        PerlIO_printf( Perl_debug_log,
+                                            " Scanning for legal start char...\n");
+                                    }
+                                );            
+                                while ( uc <= (U8*)last_start  && !BITMAP_TEST(bitmap,*uc) ) {
+                                    uc++;
+                                }
+                                s= (char *)uc;
+                            }
+                            if (uc >(U8*)last_start) break;
+                        }
+                                            
+                        if ( word ) {
+                            U8 *lpos= points[ (pointpos - trie->wordlen[word-1] ) % maxlen ];
+                            if (!leftmost || lpos < leftmost) {
+                                DEBUG_r(accepted_word=word);
+                                leftmost= lpos;
+                            }
+                            if (base==0) break;
+                            
+                        }
+                        points[pointpos++ % maxlen]= uc;
+                       REXEC_TRIE_READ_CHAR(trie_type, trie, widecharmap, uc,
+                                            uscan, len, uvc, charid, foldlen,
+                                            foldbuf, uniflags);
+                        DEBUG_TRIE_EXECUTE_r({
+                            dump_exec_pos( (char *)uc, c, strend, real_start, 
+                                s,   do_utf8 );
+                            PerlIO_printf(Perl_debug_log,
+                                " Charid:%3u CP:%4"UVxf" ",
+                                 charid, uvc);
+                        });
+
+                        do {
+#ifdef DEBUGGING
+                            word = aho->states[ state ].wordnum;
+#endif
+                            base = aho->states[ state ].trans.base;
+
+                            DEBUG_TRIE_EXECUTE_r({
+                                if (failed) 
+                                    dump_exec_pos( (char *)uc, c, strend, real_start, 
+                                        s,   do_utf8 );
+                                PerlIO_printf( Perl_debug_log,
+                                    "%sState: %4"UVxf", word=%"UVxf,
+                                    failed ? " Fail transition to " : "",
+                                    (UV)state, (UV)word);
+                            });
+                            if ( base ) {
+                                U32 tmp;
+                                if (charid &&
+                                     (base + charid > trie->uniquecharcount )
+                                     && (base + charid - 1 - trie->uniquecharcount
+                                            < trie->lasttrans)
+                                     && trie->trans[base + charid - 1 -
+                                            trie->uniquecharcount].check == state
+                                     && (tmp=trie->trans[base + charid - 1 -
+                                        trie->uniquecharcount ].next))
+                                {
+                                    DEBUG_TRIE_EXECUTE_r(
+                                        PerlIO_printf( Perl_debug_log," - legal\n"));
+                                    state = tmp;
+                                    break;
+                                }
+                                else {
+                                    DEBUG_TRIE_EXECUTE_r(
+                                        PerlIO_printf( Perl_debug_log," - fail\n"));
+                                    failed = 1;
+                                    state = aho->fail[state];
+                                }
+                            }
+                            else {
+                                /* we must be accepting here */
+                                DEBUG_TRIE_EXECUTE_r(
+                                        PerlIO_printf( Perl_debug_log," - accepting\n"));
+                                failed = 1;
+                                break;
+                            }
+                        } while(state);
+                        uc += len;
+                        if (failed) {
+                            if (leftmost)
+                                break;
+                            if (!state) state = 1;
+                        }
+                    }
+                    if ( aho->states[ state ].wordnum ) {
+                        U8 *lpos = points[ (pointpos - trie->wordlen[aho->states[ state ].wordnum-1]) % maxlen ];
+                        if (!leftmost || lpos < leftmost) {
+                            DEBUG_r(accepted_word=aho->states[ state ].wordnum);
+                            leftmost = lpos;
+                        }
+                    }
+                    if (leftmost) {
+                        s = (char*)leftmost;
+                        DEBUG_TRIE_EXECUTE_r({
+                            PerlIO_printf( 
+                                Perl_debug_log,"Matches word #%"UVxf" at position %"IVdf". Trying full pattern...\n",
+                                (UV)accepted_word, (IV)(s - real_start)
+                            );
+                        });
+                        if (!reginfo || regtry(reginfo, &s)) {
+                            FREETMPS;
+                           LEAVE;
+                            goto got_it;
+                        }
+                        s = HOPc(s,1);
+                        DEBUG_TRIE_EXECUTE_r({
+                            PerlIO_printf( Perl_debug_log,"Pattern failed. Looking for new start point...\n");
+                        });
+                    } else {
+                        DEBUG_TRIE_EXECUTE_r(
+                            PerlIO_printf( Perl_debug_log,"No match.\n"));
+                        break;
+                    }
+                }
+                FREETMPS;
+                LEAVE;
+           }
+           break;
+       default:
+           Perl_croak(aTHX_ "panic: unknown regstclass %d", (int)OP(c));
+           break;
+       }
+       return 0;
+      got_it:
+       return s;
+}
+
+
+/*
+ - regexec_flags - match a regexp against a string
+ */
+I32
+Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, register char *strend,
+             char *strbeg, I32 minend, SV *sv, void *data, U32 flags)
+/* strend: pointer to null at end of string */
+/* strbeg: real beginning of string */
+/* minend: end of match must be >=minend after stringarg. */
+/* data: May be used for some additional optimizations. 
+         Currently its only used, with a U32 cast, for transmitting 
+         the ganch offset when doing a /g match. This will change */
+/* nosave: For optimizations. */
+{
+    dVAR;
+    struct regexp *const prog = (struct regexp *)SvANY(rx);
+    /*register*/ char *s;
+    register regnode *c;
+    /*register*/ char *startpos = stringarg;
+    I32 minlen;                /* must match at least this many chars */
+    I32 dontbother = 0;        /* how many characters not to try at end */
+    I32 end_shift = 0;                 /* Same for the end. */         /* CC */
+    I32 scream_pos = -1;               /* Internal iterator of scream. */
+    char *scream_olds = NULL;
+    const bool do_utf8 = (bool)DO_UTF8(sv);
+    I32 multiline;
+    RXi_GET_DECL(prog,progi);
+    regmatch_info reginfo;  /* create some info to pass to regtry etc */
+    regexp_paren_pair *swap = NULL;
+    GET_RE_DEBUG_FLAGS_DECL;
+
+    PERL_ARGS_ASSERT_REGEXEC_FLAGS;
+    PERL_UNUSED_ARG(data);
+
+    /* Be paranoid... */
+    if (prog == NULL || startpos == NULL) {
+       Perl_croak(aTHX_ "NULL regexp parameter");
+       return 0;
+    }
+
+    multiline = prog->extflags & RXf_PMf_MULTILINE;
+    reginfo.prog = rx;  /* Yes, sorry that this is confusing.  */
+
+    RX_MATCH_UTF8_set(rx, do_utf8);
+    DEBUG_EXECUTE_r( 
+        debug_start_match(rx, do_utf8, startpos, strend, 
+        "Matching");
+    );
+
+    minlen = prog->minlen;
+    
+    if (strend - startpos < (minlen+(prog->check_offset_min<0?prog->check_offset_min:0))) {
+        DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+                             "String too short [regexec_flags]...\n"));
+       goto phooey;
+    }
+
+    
+    /* Check validity of program. */
+    if (UCHARAT(progi->program) != REG_MAGIC) {
+       Perl_croak(aTHX_ "corrupted regexp program");
+    }
+
+    PL_reg_flags = 0;
+    PL_reg_eval_set = 0;
+    PL_reg_maxiter = 0;
+
+    if (RX_UTF8(rx))
+       PL_reg_flags |= RF_utf8;
+
+    /* Mark beginning of line for ^ and lookbehind. */
+    reginfo.bol = startpos; /* XXX not used ??? */
+    PL_bostr  = strbeg;
+    reginfo.sv = sv;
+
+    /* Mark end of line for $ (and such) */
+    PL_regeol = strend;
+
+    /* see how far we have to get to not match where we matched before */
+    reginfo.till = startpos+minend;
+
+    /* If there is a "must appear" string, look for it. */
+    s = startpos;
+
+    if (prog->extflags & RXf_GPOS_SEEN) { /* Need to set reginfo->ganch */
+       MAGIC *mg;
+       if (flags & REXEC_IGNOREPOS){   /* Means: check only at start */
+           reginfo.ganch = startpos + prog->gofs;
+           DEBUG_GPOS_r(PerlIO_printf(Perl_debug_log,
+             "GPOS IGNOREPOS: reginfo.ganch = startpos + %"UVxf"\n",(UV)prog->gofs));
+       } else if (sv && SvTYPE(sv) >= SVt_PVMG
+                 && SvMAGIC(sv)
+                 && (mg = mg_find(sv, PERL_MAGIC_regex_global))
+                 && mg->mg_len >= 0) {
+           reginfo.ganch = strbeg + mg->mg_len;        /* Defined pos() */
+           DEBUG_GPOS_r(PerlIO_printf(Perl_debug_log,
+               "GPOS MAGIC: reginfo.ganch = strbeg + %"IVdf"\n",(IV)mg->mg_len));
+
+           if (prog->extflags & RXf_ANCH_GPOS) {
+               if (s > reginfo.ganch)
+                   goto phooey;
+               s = reginfo.ganch - prog->gofs;
+               DEBUG_GPOS_r(PerlIO_printf(Perl_debug_log,
+                    "GPOS ANCH_GPOS: s = ganch - %"UVxf"\n",(UV)prog->gofs));
+               if (s < strbeg)
+                   goto phooey;
+           }
+       }
+       else if (data) {
+           reginfo.ganch = strbeg + PTR2UV(data);
+            DEBUG_GPOS_r(PerlIO_printf(Perl_debug_log,
+                "GPOS DATA: reginfo.ganch= strbeg + %"UVxf"\n",PTR2UV(data)));
+
+       } else {                                /* pos() not defined */
+           reginfo.ganch = strbeg;
+            DEBUG_GPOS_r(PerlIO_printf(Perl_debug_log,
+                "GPOS: reginfo.ganch = strbeg\n"));
+       }
+    }
+    if (PL_curpm && (PM_GETRE(PL_curpm) == rx)) {
+        /* We have to be careful. If the previous successful match
+           was from this regex we don't want a subsequent partially
+           successful match to clobber the old results.
+           So when we detect this possibility we add a swap buffer
+           to the re, and switch the buffer each match. If we fail
+           we switch it back, otherwise we leave it swapped.
+        */
+        swap = prog->offs;
+        /* do we need a save destructor here for eval dies? */
+        Newxz(prog->offs, (prog->nparens + 1), regexp_paren_pair);
+    }
+    if (!(flags & REXEC_CHECKED) && (prog->check_substr != NULL || prog->check_utf8 != NULL)) {
+       re_scream_pos_data d;
+
+       d.scream_olds = &scream_olds;
+       d.scream_pos = &scream_pos;
+       s = re_intuit_start(rx, sv, s, strend, flags, &d);
+       if (!s) {
+           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Not present...\n"));
+           goto phooey;        /* not present */
+       }
+    }
+
+
+
+    /* Simplest case:  anchored match need be tried only once. */
+    /*  [unless only anchor is BOL and multiline is set] */
+    if (prog->extflags & (RXf_ANCH & ~RXf_ANCH_GPOS)) {
+       if (s == startpos && regtry(&reginfo, &startpos))
+           goto got_it;
+       else if (multiline || (prog->intflags & PREGf_IMPLICIT)
+                || (prog->extflags & RXf_ANCH_MBOL)) /* XXXX SBOL? */
+       {
+           char *end;
+
+           if (minlen)
+               dontbother = minlen - 1;
+           end = HOP3c(strend, -dontbother, strbeg) - 1;
+           /* for multiline we only have to try after newlines */
+           if (prog->check_substr || prog->check_utf8) {
+                /* because of the goto we can not easily reuse the macros for bifurcating the
+                   unicode/non-unicode match modes here like we do elsewhere - demerphq */
+                if (do_utf8) {
+                    if (s == startpos)
+                        goto after_try_utf8;
+                    while (1) {
+                        if (regtry(&reginfo, &s)) {
+                            goto got_it;
+                        }
+                      after_try_utf8:
+                        if (s > end) {
+                            goto phooey;
+                        }
+                        if (prog->extflags & RXf_USE_INTUIT) {
+                            s = re_intuit_start(rx, sv, s + UTF8SKIP(s), strend, flags, NULL);
+                            if (!s) {
+                                goto phooey;
+                            }
+                        }
+                        else {
+                            s += UTF8SKIP(s);
+                        }
+                    }
+                } /* end search for check string in unicode */
+                else {
+                    if (s == startpos) {
+                        goto after_try_latin;
+                    }
+                    while (1) {
+                        if (regtry(&reginfo, &s)) {
+                            goto got_it;
+                        }
+                      after_try_latin:
+                        if (s > end) {
+                            goto phooey;
+                        }
+                        if (prog->extflags & RXf_USE_INTUIT) {
+                            s = re_intuit_start(rx, sv, s + 1, strend, flags, NULL);
+                            if (!s) {
+                                goto phooey;
+                            }
+                        }
+                        else {
+                            s++;
+                        }
+                    }
+                } /* end search for check string in latin*/
+           } /* end search for check string */
+           else { /* search for newline */
+               if (s > startpos) {
+                    /*XXX: The s-- is almost definitely wrong here under unicode - demeprhq*/
+                   s--;
+               }
+                /* We can use a more efficient search as newlines are the same in unicode as they are in latin */
+               while (s < end) {
+                   if (*s++ == '\n') { /* don't need PL_utf8skip here */
+                       if (regtry(&reginfo, &s))
+                           goto got_it;
+                   }
+               }
+           } /* end search for newline */
+       } /* end anchored/multiline check string search */
+       goto phooey;
+    } else if (RXf_GPOS_CHECK == (prog->extflags & RXf_GPOS_CHECK)) 
+    {
+        /* the warning about reginfo.ganch being used without intialization
+           is bogus -- we set it above, when prog->extflags & RXf_GPOS_SEEN 
+           and we only enter this block when the same bit is set. */
+        char *tmp_s = reginfo.ganch - prog->gofs;
+
+       if (tmp_s >= strbeg && regtry(&reginfo, &tmp_s))
+           goto got_it;
+       goto phooey;
+    }
+
+    /* Messy cases:  unanchored match. */
+    if ((prog->anchored_substr || prog->anchored_utf8) && prog->intflags & PREGf_SKIP) {
+       /* we have /x+whatever/ */
+       /* it must be a one character string (XXXX Except UTF?) */
+       char ch;
+#ifdef DEBUGGING
+       int did_match = 0;
+#endif
+       if (!(do_utf8 ? prog->anchored_utf8 : prog->anchored_substr))
+           do_utf8 ? to_utf8_substr(prog) : to_byte_substr(prog);
+       ch = SvPVX_const(do_utf8 ? prog->anchored_utf8 : prog->anchored_substr)[0];
+
+       if (do_utf8) {
+           REXEC_FBC_SCAN(
+               if (*s == ch) {
+                   DEBUG_EXECUTE_r( did_match = 1 );
+                   if (regtry(&reginfo, &s)) goto got_it;
+                   s += UTF8SKIP(s);
+                   while (s < strend && *s == ch)
+                       s += UTF8SKIP(s);
+               }
+           );
+       }
+       else {
+           REXEC_FBC_SCAN(
+               if (*s == ch) {
+                   DEBUG_EXECUTE_r( did_match = 1 );
+                   if (regtry(&reginfo, &s)) goto got_it;
+                   s++;
+                   while (s < strend && *s == ch)
+                       s++;
+               }
+           );
+       }
+       DEBUG_EXECUTE_r(if (!did_match)
+               PerlIO_printf(Perl_debug_log,
+                                  "Did not find anchored character...\n")
+               );
+    }
+    else if (prog->anchored_substr != NULL
+             || prog->anchored_utf8 != NULL
+             || ((prog->float_substr != NULL || prog->float_utf8 != NULL)
+                 && prog->float_max_offset < strend - s)) {
+       SV *must;
+       I32 back_max;
+       I32 back_min;
+       char *last;
+       char *last1;            /* Last position checked before */
+#ifdef DEBUGGING
+       int did_match = 0;
+#endif
+       if (prog->anchored_substr || prog->anchored_utf8) {
+           if (!(do_utf8 ? prog->anchored_utf8 : prog->anchored_substr))
+               do_utf8 ? to_utf8_substr(prog) : to_byte_substr(prog);
+           must = do_utf8 ? prog->anchored_utf8 : prog->anchored_substr;
+           back_max = back_min = prog->anchored_offset;
+       } else {
+           if (!(do_utf8 ? prog->float_utf8 : prog->float_substr))
+               do_utf8 ? to_utf8_substr(prog) : to_byte_substr(prog);
+           must = do_utf8 ? prog->float_utf8 : prog->float_substr;
+           back_max = prog->float_max_offset;
+           back_min = prog->float_min_offset;
+       }
+       
+           
+       if (must == &PL_sv_undef)
+           /* could not downgrade utf8 check substring, so must fail */
+           goto phooey;
+
+        if (back_min<0) {
+           last = strend;
+       } else {
+            last = HOP3c(strend,       /* Cannot start after this */
+                 -(I32)(CHR_SVLEN(must)
+                        - (SvTAIL(must) != 0) + back_min), strbeg);
+        }
+       if (s > PL_bostr)
+           last1 = HOPc(s, -1);
+       else
+           last1 = s - 1;      /* bogus */
+
+       /* XXXX check_substr already used to find "s", can optimize if
+          check_substr==must. */
+       scream_pos = -1;
+       dontbother = end_shift;
+       strend = HOPc(strend, -dontbother);
+       while ( (s <= last) &&
+               ((flags & REXEC_SCREAM)
+                ? (s = screaminstr(sv, must, HOP3c(s, back_min, (back_min<0 ? strbeg : strend)) - strbeg,
+                                   end_shift, &scream_pos, 0))
+                : (s = fbm_instr((unsigned char*)HOP3(s, back_min, (back_min<0 ? strbeg : strend)),
+                                 (unsigned char*)strend, must,
+                                 multiline ? FBMrf_MULTILINE : 0))) ) {
+           /* we may be pointing at the wrong string */
+           if ((flags & REXEC_SCREAM) && RXp_MATCH_COPIED(prog))
+               s = strbeg + (s - SvPVX_const(sv));
+           DEBUG_EXECUTE_r( did_match = 1 );
+           if (HOPc(s, -back_max) > last1) {
+               last1 = HOPc(s, -back_min);
+               s = HOPc(s, -back_max);
+           }
+           else {
+               char * const t = (last1 >= PL_bostr) ? HOPc(last1, 1) : last1 + 1;
+
+               last1 = HOPc(s, -back_min);
+               s = t;
+           }
+           if (do_utf8) {
+               while (s <= last1) {
+                   if (regtry(&reginfo, &s))
+                       goto got_it;
+                   s += UTF8SKIP(s);
+               }
+           }
+           else {
+               while (s <= last1) {
+                   if (regtry(&reginfo, &s))
+                       goto got_it;
+                   s++;
+               }
+           }
+       }
+       DEBUG_EXECUTE_r(if (!did_match) {
+            RE_PV_QUOTED_DECL(quoted, do_utf8, PERL_DEBUG_PAD_ZERO(0), 
+                SvPVX_const(must), RE_SV_DUMPLEN(must), 30);
+            PerlIO_printf(Perl_debug_log, "Did not find %s substr %s%s...\n",
+                             ((must == prog->anchored_substr || must == prog->anchored_utf8)
+                              ? "anchored" : "floating"),
+                quoted, RE_SV_TAIL(must));
+        });                
+       goto phooey;
+    }
+    else if ( (c = progi->regstclass) ) {
+       if (minlen) {
+           const OPCODE op = OP(progi->regstclass);
+           /* don't bother with what can't match */
+           if (PL_regkind[op] != EXACT && op != CANY && PL_regkind[op] != TRIE)
+               strend = HOPc(strend, -(minlen - 1));
+       }
+       DEBUG_EXECUTE_r({
+           SV * const prop = sv_newmortal();
+           regprop(prog, prop, c);
+           {
+               RE_PV_QUOTED_DECL(quoted,do_utf8,PERL_DEBUG_PAD_ZERO(1),
+                   s,strend-s,60);
+               PerlIO_printf(Perl_debug_log,
+                   "Matching stclass %.*s against %s (%d chars)\n",
+                   (int)SvCUR(prop), SvPVX_const(prop),
+                    quoted, (int)(strend - s));
+           }
+       });
+        if (find_byclass(prog, c, s, strend, &reginfo))
+           goto got_it;
+       DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Contradicts stclass... [regexec_flags]\n"));
+    }
+    else {
+       dontbother = 0;
+       if (prog->float_substr != NULL || prog->float_utf8 != NULL) {
+           /* Trim the end. */
+           char *last;
+           SV* float_real;
+
+           if (!(do_utf8 ? prog->float_utf8 : prog->float_substr))
+               do_utf8 ? to_utf8_substr(prog) : to_byte_substr(prog);
+           float_real = do_utf8 ? prog->float_utf8 : prog->float_substr;
+
+           if (flags & REXEC_SCREAM) {
+               last = screaminstr(sv, float_real, s - strbeg,
+                                  end_shift, &scream_pos, 1); /* last one */
+               if (!last)
+                   last = scream_olds; /* Only one occurrence. */
+               /* we may be pointing at the wrong string */
+               else if (RXp_MATCH_COPIED(prog))
+                   s = strbeg + (s - SvPVX_const(sv));
+           }
+           else {
+               STRLEN len;
+                const char * const little = SvPV_const(float_real, len);
+
+               if (SvTAIL(float_real)) {
+                   if (memEQ(strend - len + 1, little, len - 1))
+                       last = strend - len + 1;
+                   else if (!multiline)
+                       last = memEQ(strend - len, little, len)
+                           ? strend - len : NULL;
+                   else
+                       goto find_last;
+               } else {
+                 find_last:
+                   if (len)
+                       last = rninstr(s, strend, little, little + len);
+                   else
+                       last = strend;  /* matching "$" */
+               }
+           }
+           if (last == NULL) {
+               DEBUG_EXECUTE_r(
+                   PerlIO_printf(Perl_debug_log,
+                       "%sCan't trim the tail, match fails (should not happen)%s\n",
+                       PL_colors[4], PL_colors[5]));
+               goto phooey; /* Should not happen! */
+           }
+           dontbother = strend - last + prog->float_min_offset;
+       }
+       if (minlen && (dontbother < minlen))
+           dontbother = minlen - 1;
+       strend -= dontbother;              /* this one's always in bytes! */
+       /* We don't know much -- general case. */
+       if (do_utf8) {
+           for (;;) {
+               if (regtry(&reginfo, &s))
+                   goto got_it;
+               if (s >= strend)
+                   break;
+               s += UTF8SKIP(s);
+           };
+       }
+       else {
+           do {
+               if (regtry(&reginfo, &s))
+                   goto got_it;
+           } while (s++ < strend);
+       }
+    }
+
+    /* Failure. */
+    goto phooey;
+
+got_it:
+    Safefree(swap);
+    RX_MATCH_TAINTED_set(rx, PL_reg_flags & RF_tainted);
+
+    if (PL_reg_eval_set)
+       restore_pos(aTHX_ prog);
+    if (RXp_PAREN_NAMES(prog)) 
+        (void)hv_iterinit(RXp_PAREN_NAMES(prog));
+
+    /* make sure $`, $&, $', and $digit will work later */
+    if ( !(flags & REXEC_NOT_FIRST) ) {
+       RX_MATCH_COPY_FREE(rx);
+       if (flags & REXEC_COPY_STR) {
+           const I32 i = PL_regeol - startpos + (stringarg - strbeg);
+#ifdef PERL_OLD_COPY_ON_WRITE
+           if ((SvIsCOW(sv)
+                || (SvFLAGS(sv) & CAN_COW_MASK) == CAN_COW_FLAGS)) {
+               if (DEBUG_C_TEST) {
+                   PerlIO_printf(Perl_debug_log,
+                                 "Copy on write: regexp capture, type %d\n",
+                                 (int) SvTYPE(sv));
+               }
+               prog->saved_copy = sv_setsv_cow(prog->saved_copy, sv);
+               prog->subbeg = (char *)SvPVX_const(prog->saved_copy);
+               assert (SvPOKp(prog->saved_copy));
+           } else
+#endif
+           {
+               RX_MATCH_COPIED_on(rx);
+               s = savepvn(strbeg, i);
+               prog->subbeg = s;
+           }
+           prog->sublen = i;
+       }
+       else {
+           prog->subbeg = strbeg;
+           prog->sublen = PL_regeol - strbeg;  /* strend may have been modified */
+       }
+    }
+
+    return 1;
+
+phooey:
+    DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%sMatch failed%s\n",
+                         PL_colors[4], PL_colors[5]));
+    if (PL_reg_eval_set)
+       restore_pos(aTHX_ prog);
+    if (swap) {
+        /* we failed :-( roll it back */
+        Safefree(prog->offs);
+        prog->offs = swap;
+    }
+
+    return 0;
+}
+
+
+/*
+ - regtry - try match at specific point
+ */
+STATIC I32                     /* 0 failure, 1 success */
+S_regtry(pTHX_ regmatch_info *reginfo, char **startpos)
+{
+    dVAR;
+    CHECKPOINT lastcp;
+    REGEXP *const rx = reginfo->prog;
+    regexp *const prog = (struct regexp *)SvANY(rx);
+    RXi_GET_DECL(prog,progi);
+    GET_RE_DEBUG_FLAGS_DECL;
+
+    PERL_ARGS_ASSERT_REGTRY;
+
+    reginfo->cutpoint=NULL;
+
+    if ((prog->extflags & RXf_EVAL_SEEN) && !PL_reg_eval_set) {
+       MAGIC *mg;
+
+       PL_reg_eval_set = RS_init;
+       DEBUG_EXECUTE_r(DEBUG_s(
+           PerlIO_printf(Perl_debug_log, "  setting stack tmpbase at %"IVdf"\n",
+                         (IV)(PL_stack_sp - PL_stack_base));
+           ));
+       SAVESTACK_CXPOS();
+       cxstack[cxstack_ix].blk_oldsp = PL_stack_sp - PL_stack_base;
+       /* Otherwise OP_NEXTSTATE will free whatever on stack now.  */
+       SAVETMPS;
+       /* Apparently this is not needed, judging by wantarray. */
+       /* SAVEI8(cxstack[cxstack_ix].blk_gimme);
+          cxstack[cxstack_ix].blk_gimme = G_SCALAR; */
+
+       if (reginfo->sv) {
+           /* Make $_ available to executed code. */
+           if (reginfo->sv != DEFSV) {
+               SAVE_DEFSV;
+               DEFSV_set(reginfo->sv);
+           }
+       
+           if (!(SvTYPE(reginfo->sv) >= SVt_PVMG && SvMAGIC(reginfo->sv)
+                 && (mg = mg_find(reginfo->sv, PERL_MAGIC_regex_global)))) {
+               /* prepare for quick setting of pos */
+#ifdef PERL_OLD_COPY_ON_WRITE
+               if (SvIsCOW(reginfo->sv))
+                   sv_force_normal_flags(reginfo->sv, 0);
+#endif
+               mg = sv_magicext(reginfo->sv, NULL, PERL_MAGIC_regex_global,
+                                &PL_vtbl_mglob, NULL, 0);
+               mg->mg_len = -1;
+           }
+           PL_reg_magic    = mg;
+           PL_reg_oldpos   = mg->mg_len;
+           SAVEDESTRUCTOR_X(restore_pos, prog);
+        }
+        if (!PL_reg_curpm) {
+           Newxz(PL_reg_curpm, 1, PMOP);
+#ifdef USE_ITHREADS
+            {
+               SV* const repointer = &PL_sv_undef;
+                /* this regexp is also owned by the new PL_reg_curpm, which
+                  will try to free it.  */
+                av_push(PL_regex_padav, repointer);
+                PL_reg_curpm->op_pmoffset = av_len(PL_regex_padav);
+                PL_regex_pad = AvARRAY(PL_regex_padav);
+            }
+#endif      
+        }
+#ifdef USE_ITHREADS
+       /* It seems that non-ithreads works both with and without this code.
+          So for efficiency reasons it seems best not to have the code
+          compiled when it is not needed.  */
+       /* This is safe against NULLs: */
+       ReREFCNT_dec(PM_GETRE(PL_reg_curpm));
+       /* PM_reg_curpm owns a reference to this regexp.  */
+       ReREFCNT_inc(rx);
+#endif
+       PM_SETRE(PL_reg_curpm, rx);
+       PL_reg_oldcurpm = PL_curpm;
+       PL_curpm = PL_reg_curpm;
+       if (RXp_MATCH_COPIED(prog)) {
+           /*  Here is a serious problem: we cannot rewrite subbeg,
+               since it may be needed if this match fails.  Thus
+               $` inside (?{}) could fail... */
+           PL_reg_oldsaved = prog->subbeg;
+           PL_reg_oldsavedlen = prog->sublen;
+#ifdef PERL_OLD_COPY_ON_WRITE
+           PL_nrs = prog->saved_copy;
+#endif
+           RXp_MATCH_COPIED_off(prog);
+       }
+       else
+           PL_reg_oldsaved = NULL;
+       prog->subbeg = PL_bostr;
+       prog->sublen = PL_regeol - PL_bostr; /* strend may have been modified */
+    }
+    DEBUG_EXECUTE_r(PL_reg_starttry = *startpos);
+    prog->offs[0].start = *startpos - PL_bostr;
+    PL_reginput = *startpos;
+    PL_reglastparen = &prog->lastparen;
+    PL_reglastcloseparen = &prog->lastcloseparen;
+    prog->lastparen = 0;
+    prog->lastcloseparen = 0;
+    PL_regsize = 0;
+    PL_regoffs = prog->offs;
+    if (PL_reg_start_tmpl <= prog->nparens) {
+       PL_reg_start_tmpl = prog->nparens*3/2 + 3;
+        if(PL_reg_start_tmp)
+            Renew(PL_reg_start_tmp, PL_reg_start_tmpl, char*);
+        else
+            Newx(PL_reg_start_tmp, PL_reg_start_tmpl, char*);
+    }
+
+    /* XXXX What this code is doing here?!!!  There should be no need
+       to do this again and again, PL_reglastparen should take care of
+       this!  --ilya*/
+
+    /* Tests pat.t#187 and split.t#{13,14} seem to depend on this code.
+     * Actually, the code in regcppop() (which Ilya may be meaning by
+     * PL_reglastparen), is not needed at all by the test suite
+     * (op/regexp, op/pat, op/split), but that code is needed otherwise
+     * this erroneously leaves $1 defined: "1" =~ /^(?:(\d)x)?\d$/
+     * Meanwhile, this code *is* needed for the
+     * above-mentioned test suite tests to succeed.  The common theme
+     * on those tests seems to be returning null fields from matches.
+     * --jhi updated by dapm */
+#if 1
+    if (prog->nparens) {
+       regexp_paren_pair *pp = PL_regoffs;
+       register I32 i;
+       for (i = prog->nparens; i > (I32)*PL_reglastparen; i--) {
+           ++pp;
+           pp->start = -1;
+           pp->end = -1;
+       }
+    }
+#endif
+    REGCP_SET(lastcp);
+    if (regmatch(reginfo, progi->program + 1)) {
+       PL_regoffs[0].end = PL_reginput - PL_bostr;
+       return 1;
+    }
+    if (reginfo->cutpoint)
+        *startpos= reginfo->cutpoint;
+    REGCP_UNWIND(lastcp);
+    return 0;
+}
+
+
+#define sayYES goto yes
+#define sayNO goto no
+#define sayNO_SILENT goto no_silent
+
+/* we dont use STMT_START/END here because it leads to 
+   "unreachable code" warnings, which are bogus, but distracting. */
+#define CACHEsayNO \
+    if (ST.cache_mask) \
+       PL_reg_poscache[ST.cache_offset] |= ST.cache_mask; \
+    sayNO
+
+/* this is used to determine how far from the left messages like
+   'failed...' are printed. It should be set such that messages 
+   are inline with the regop output that created them.
+*/
+#define REPORT_CODE_OFF 32
+
+
+/* Make sure there is a test for this +1 options in re_tests */
+#define TRIE_INITAL_ACCEPT_BUFFLEN 4;
+
+#define CHRTEST_UNINIT -1001 /* c1/c2 haven't been calculated yet */
+#define CHRTEST_VOID   -1000 /* the c1/c2 "next char" test should be skipped */
+
+#define SLAB_FIRST(s) (&(s)->states[0])
+#define SLAB_LAST(s)  (&(s)->states[PERL_REGMATCH_SLAB_SLOTS-1])
+
+/* grab a new slab and return the first slot in it */
+
+STATIC regmatch_state *
+S_push_slab(pTHX)
+{
+#if PERL_VERSION < 9 && !defined(PERL_CORE)
+    dMY_CXT;
+#endif
+    regmatch_slab *s = PL_regmatch_slab->next;
+    if (!s) {
+       Newx(s, 1, regmatch_slab);
+       s->prev = PL_regmatch_slab;
+       s->next = NULL;
+       PL_regmatch_slab->next = s;
+    }
+    PL_regmatch_slab = s;
+    return SLAB_FIRST(s);
+}
+
+
+/* push a new state then goto it */
+
+#define PUSH_STATE_GOTO(state, node) \
+    scan = node; \
+    st->resume_state = state; \
+    goto push_state;
+
+/* push a new state with success backtracking, then goto it */
+
+#define PUSH_YES_STATE_GOTO(state, node) \
+    scan = node; \
+    st->resume_state = state; \
+    goto push_yes_state;
+
+
+
+/*
+
+regmatch() - main matching routine
+
+This is basically one big switch statement in a loop. We execute an op,
+set 'next' to point the next op, and continue. If we come to a point which
+we may need to backtrack to on failure such as (A|B|C), we push a
+backtrack state onto the backtrack stack. On failure, we pop the top
+state, and re-enter the loop at the state indicated. If there are no more
+states to pop, we return failure.
+
+Sometimes we also need to backtrack on success; for example /A+/, where
+after successfully matching one A, we need to go back and try to
+match another one; similarly for lookahead assertions: if the assertion
+completes successfully, we backtrack to the state just before the assertion
+and then carry on.  In these cases, the pushed state is marked as
+'backtrack on success too'. This marking is in fact done by a chain of
+pointers, each pointing to the previous 'yes' state. On success, we pop to
+the nearest yes state, discarding any intermediate failure-only states.
+Sometimes a yes state is pushed just to force some cleanup code to be
+called at the end of a successful match or submatch; e.g. (??{$re}) uses
+it to free the inner regex.
+
+Note that failure backtracking rewinds the cursor position, while
+success backtracking leaves it alone.
+
+A pattern is complete when the END op is executed, while a subpattern
+such as (?=foo) is complete when the SUCCESS op is executed. Both of these
+ops trigger the "pop to last yes state if any, otherwise return true"
+behaviour.
+
+A common convention in this function is to use A and B to refer to the two
+subpatterns (or to the first nodes thereof) in patterns like /A*B/: so A is
+the subpattern to be matched possibly multiple times, while B is the entire
+rest of the pattern. Variable and state names reflect this convention.
+
+The states in the main switch are the union of ops and failure/success of
+substates associated with with that op.  For example, IFMATCH is the op
+that does lookahead assertions /(?=A)B/ and so the IFMATCH state means
+'execute IFMATCH'; while IFMATCH_A is a state saying that we have just
+successfully matched A and IFMATCH_A_fail is a state saying that we have
+just failed to match A. Resume states always come in pairs. The backtrack
+state we push is marked as 'IFMATCH_A', but when that is popped, we resume
+at IFMATCH_A or IFMATCH_A_fail, depending on whether we are backtracking
+on success or failure.
+
+The struct that holds a backtracking state is actually a big union, with
+one variant for each major type of op. The variable st points to the
+top-most backtrack struct. To make the code clearer, within each
+block of code we #define ST to alias the relevant union.
+
+Here's a concrete example of a (vastly oversimplified) IFMATCH
+implementation:
+
+    switch (state) {
+    ....
+
+#define ST st->u.ifmatch
+
+    case IFMATCH: // we are executing the IFMATCH op, (?=A)B
+       ST.foo = ...; // some state we wish to save
+       ...
+       // push a yes backtrack state with a resume value of
+       // IFMATCH_A/IFMATCH_A_fail, then continue execution at the
+       // first node of A:
+       PUSH_YES_STATE_GOTO(IFMATCH_A, A);
+       // NOTREACHED
+
+    case IFMATCH_A: // we have successfully executed A; now continue with B
+       next = B;
+       bar = ST.foo; // do something with the preserved value
+       break;
+
+    case IFMATCH_A_fail: // A failed, so the assertion failed
+       ...;   // do some housekeeping, then ...
+       sayNO; // propagate the failure
+
+#undef ST
+
+    ...
+    }
+
+For any old-timers reading this who are familiar with the old recursive
+approach, the code above is equivalent to:
+
+    case IFMATCH: // we are executing the IFMATCH op, (?=A)B
+    {
+       int foo = ...
+       ...
+       if (regmatch(A)) {
+           next = B;
+           bar = foo;
+           break;
+       }
+       ...;   // do some housekeeping, then ...
+       sayNO; // propagate the failure
+    }
+
+The topmost backtrack state, pointed to by st, is usually free. If you
+want to claim it, populate any ST.foo fields in it with values you wish to
+save, then do one of
+
+       PUSH_STATE_GOTO(resume_state, node);
+       PUSH_YES_STATE_GOTO(resume_state, node);
+
+which sets that backtrack state's resume value to 'resume_state', pushes a
+new free entry to the top of the backtrack stack, then goes to 'node'.
+On backtracking, the free slot is popped, and the saved state becomes the
+new free state. An ST.foo field in this new top state can be temporarily
+accessed to retrieve values, but once the main loop is re-entered, it
+becomes available for reuse.
+
+Note that the depth of the backtrack stack constantly increases during the
+left-to-right execution of the pattern, rather than going up and down with
+the pattern nesting. For example the stack is at its maximum at Z at the
+end of the pattern, rather than at X in the following:
+
+    /(((X)+)+)+....(Y)+....Z/
+
+The only exceptions to this are lookahead/behind assertions and the cut,
+(?>A), which pop all the backtrack states associated with A before
+continuing.
+Bascktrack state structs are allocated in slabs of about 4K in size.
+PL_regmatch_state and st always point to the currently active state,
+and PL_regmatch_slab points to the slab currently containing
+PL_regmatch_state.  The first time regmatch() is called, the first slab is
+allocated, and is never freed until interpreter destruction. When the slab
+is full, a new one is allocated and chained to the end. At exit from
+regmatch(), slabs allocated since entry are freed.
+
+*/
+
+#define DEBUG_STATE_pp(pp)                                 \
+    DEBUG_STATE_r({                                        \
+       DUMP_EXEC_POS(locinput, scan, do_utf8);             \
+       PerlIO_printf(Perl_debug_log,                       \
+           "    %*s"pp" %s%s%s%s%s\n",                     \
+           depth*2, "",                                    \
+           PL_reg_name[st->resume_state],                     \
+           ((st==yes_state||st==mark_state) ? "[" : ""),   \
+           ((st==yes_state) ? "Y" : ""),                   \
+           ((st==mark_state) ? "M" : ""),                  \
+           ((st==yes_state||st==mark_state) ? "]" : "")    \
+       );                                                  \
+    });
+
+
+#define REG_NODE_NUM(x) ((x) ? (int)((x)-prog) : -1)
+
+#ifdef DEBUGGING
+
+STATIC void
+S_debug_start_match(pTHX_ const REGEXP *prog, const bool do_utf8, 
+    const char *start, const char *end, const char *blurb)
+{
+    const bool utf8_pat = RX_UTF8(prog) ? 1 : 0;
+
+    PERL_ARGS_ASSERT_DEBUG_START_MATCH;
+
+    if (!PL_colorset)   
+            reginitcolors();    
+    {
+        RE_PV_QUOTED_DECL(s0, utf8_pat, PERL_DEBUG_PAD_ZERO(0), 
+            RX_PRECOMP_const(prog), RX_PRELEN(prog), 60);   
+        
+        RE_PV_QUOTED_DECL(s1, do_utf8, PERL_DEBUG_PAD_ZERO(1), 
+            start, end - start, 60); 
+        
+        PerlIO_printf(Perl_debug_log, 
+            "%s%s REx%s %s against %s\n", 
+                      PL_colors[4], blurb, PL_colors[5], s0, s1); 
+        
+        if (do_utf8||utf8_pat) 
+            PerlIO_printf(Perl_debug_log, "UTF-8 %s%s%s...\n",
+                utf8_pat ? "pattern" : "",
+                utf8_pat && do_utf8 ? " and " : "",
+                do_utf8 ? "string" : ""
+            ); 
+    }
+}
+
+STATIC void
+S_dump_exec_pos(pTHX_ const char *locinput, 
+                      const regnode *scan, 
+                      const char *loc_regeol, 
+                      const char *loc_bostr, 
+                      const char *loc_reg_starttry,
+                      const bool do_utf8)
+{
+    const int docolor = *PL_colors[0] || *PL_colors[2] || *PL_colors[4];
+    const int taill = (docolor ? 10 : 7); /* 3 chars for "> <" */
+    int l = (loc_regeol - locinput) > taill ? taill : (loc_regeol - locinput);
+    /* The part of the string before starttry has one color
+       (pref0_len chars), between starttry and current
+       position another one (pref_len - pref0_len chars),
+       after the current position the third one.
+       We assume that pref0_len <= pref_len, otherwise we
+       decrease pref0_len.  */
+    int pref_len = (locinput - loc_bostr) > (5 + taill) - l
+       ? (5 + taill) - l : locinput - loc_bostr;
+    int pref0_len;
+
+    PERL_ARGS_ASSERT_DUMP_EXEC_POS;
+
+    while (do_utf8 && UTF8_IS_CONTINUATION(*(U8*)(locinput - pref_len)))
+       pref_len++;
+    pref0_len = pref_len  - (locinput - loc_reg_starttry);
+    if (l + pref_len < (5 + taill) && l < loc_regeol - locinput)
+       l = ( loc_regeol - locinput > (5 + taill) - pref_len
+             ? (5 + taill) - pref_len : loc_regeol - locinput);
+    while (do_utf8 && UTF8_IS_CONTINUATION(*(U8*)(locinput + l)))
+       l--;
+    if (pref0_len < 0)
+       pref0_len = 0;
+    if (pref0_len > pref_len)
+       pref0_len = pref_len;
+    {
+       const int is_uni = (do_utf8 && OP(scan) != CANY) ? 1 : 0;
+
+       RE_PV_COLOR_DECL(s0,len0,is_uni,PERL_DEBUG_PAD(0),
+           (locinput - pref_len),pref0_len, 60, 4, 5);
+       
+       RE_PV_COLOR_DECL(s1,len1,is_uni,PERL_DEBUG_PAD(1),
+                   (locinput - pref_len + pref0_len),
+                   pref_len - pref0_len, 60, 2, 3);
+       
+       RE_PV_COLOR_DECL(s2,len2,is_uni,PERL_DEBUG_PAD(2),
+                   locinput, loc_regeol - locinput, 10, 0, 1);
+
+       const STRLEN tlen=len0+len1+len2;
+       PerlIO_printf(Perl_debug_log,
+                   "%4"IVdf" <%.*s%.*s%s%.*s>%*s|",
+                   (IV)(locinput - loc_bostr),
+                   len0, s0,
+                   len1, s1,
+                   (docolor ? "" : "> <"),
+                   len2, s2,
+                   (int)(tlen > 19 ? 0 :  19 - tlen),
+                   "");
+    }
+}
+
+#endif
+
+/* reg_check_named_buff_matched()
+ * Checks to see if a named buffer has matched. The data array of 
+ * buffer numbers corresponding to the buffer is expected to reside
+ * in the regexp->data->data array in the slot stored in the ARG() of
+ * node involved. Note that this routine doesn't actually care about the
+ * name, that information is not preserved from compilation to execution.
+ * Returns the index of the leftmost defined buffer with the given name
+ * or 0 if non of the buffers matched.
+ */
+STATIC I32
+S_reg_check_named_buff_matched(pTHX_ const regexp *rex, const regnode *scan)
+{
+    I32 n;
+    RXi_GET_DECL(rex,rexi);
+    SV *sv_dat= MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
+    I32 *nums=(I32*)SvPVX(sv_dat);
+
+    PERL_ARGS_ASSERT_REG_CHECK_NAMED_BUFF_MATCHED;
+
+    for ( n=0; n<SvIVX(sv_dat); n++ ) {
+        if ((I32)*PL_reglastparen >= nums[n] &&
+            PL_regoffs[nums[n]].end != -1)
+        {
+            return nums[n];
+        }
+    }
+    return 0;
+}
+
+
+/* free all slabs above current one  - called during LEAVE_SCOPE */
+
+STATIC void
+S_clear_backtrack_stack(pTHX_ void *p)
+{
+    regmatch_slab *s = PL_regmatch_slab->next;
+    PERL_UNUSED_ARG(p);
+
+    if (!s)
+       return;
+    PL_regmatch_slab->next = NULL;
+    while (s) {
+       regmatch_slab * const osl = s;
+       s = s->next;
+       Safefree(osl);
+    }
+}
+
+
+#define SETREX(Re1,Re2) \
+    if (PL_reg_eval_set) PM_SETRE((PL_reg_curpm), (Re2)); \
+    Re1 = (Re2)
+
+STATIC I32                     /* 0 failure, 1 success */
+S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
+{
+#if PERL_VERSION < 9 && !defined(PERL_CORE)
+    dMY_CXT;
+#endif
+    dVAR;
+    register const bool do_utf8 = PL_reg_match_utf8;
+    const U32 uniflags = UTF8_ALLOW_DEFAULT;
+    REGEXP *rex_sv = reginfo->prog;
+    regexp *rex = (struct regexp *)SvANY(rex_sv);
+    RXi_GET_DECL(rex,rexi);
+    I32        oldsave;
+    /* the current state. This is a cached copy of PL_regmatch_state */
+    register regmatch_state *st;
+    /* cache heavy used fields of st in registers */
+    register regnode *scan;
+    register regnode *next;
+    register U32 n = 0;        /* general value; init to avoid compiler warning */
+    register I32 ln = 0; /* len or last;  init to avoid compiler warning */
+    register char *locinput = PL_reginput;
+    register I32 nextchr;   /* is always set to UCHARAT(locinput) */
+
+    bool result = 0;       /* return value of S_regmatch */
+    int depth = 0;         /* depth of backtrack stack */
+    U32 nochange_depth = 0; /* depth of GOSUB recursion with nochange */
+    const U32 max_nochange_depth =
+        (3 * rex->nparens > MAX_RECURSE_EVAL_NOCHANGE_DEPTH) ?
+        3 * rex->nparens : MAX_RECURSE_EVAL_NOCHANGE_DEPTH;
+    regmatch_state *yes_state = NULL; /* state to pop to on success of
+                                                           subpattern */
+    /* mark_state piggy backs on the yes_state logic so that when we unwind 
+       the stack on success we can update the mark_state as we go */
+    regmatch_state *mark_state = NULL; /* last mark state we have seen */
+    regmatch_state *cur_eval = NULL; /* most recent EVAL_AB state */
+    struct regmatch_state  *cur_curlyx = NULL; /* most recent curlyx */
+    U32 state_num;
+    bool no_final = 0;      /* prevent failure from backtracking? */
+    bool do_cutgroup = 0;   /* no_final only until next branch/trie entry */
+    char *startpoint = PL_reginput;
+    SV *popmark = NULL;     /* are we looking for a mark? */
+    SV *sv_commit = NULL;   /* last mark name seen in failure */
+    SV *sv_yes_mark = NULL; /* last mark name we have seen 
+                               during a successfull match */
+    U32 lastopen = 0;       /* last open we saw */
+    bool has_cutgroup = RX_HAS_CUTGROUP(rex) ? 1 : 0;   
+    SV* const oreplsv = GvSV(PL_replgv);
+    /* these three flags are set by various ops to signal information to
+     * the very next op. They have a useful lifetime of exactly one loop
+     * iteration, and are not preserved or restored by state pushes/pops
+     */
+    bool sw = 0;           /* the condition value in (?(cond)a|b) */
+    bool minmod = 0;       /* the next "{n,m}" is a "{n,m}?" */
+    int logical = 0;       /* the following EVAL is:
+                               0: (?{...})
+                               1: (?(?{...})X|Y)
+                               2: (??{...})
+                              or the following IFMATCH/UNLESSM is:
+                               false: plain (?=foo)
+                               true:  used as a condition: (?(?=foo))
+                           */
+#ifdef DEBUGGING
+    GET_RE_DEBUG_FLAGS_DECL;
+#endif
+
+    PERL_ARGS_ASSERT_REGMATCH;
+
+    DEBUG_OPTIMISE_r( DEBUG_EXECUTE_r({
+           PerlIO_printf(Perl_debug_log,"regmatch start\n");
+    }));
+    /* on first ever call to regmatch, allocate first slab */
+    if (!PL_regmatch_slab) {
+       Newx(PL_regmatch_slab, 1, regmatch_slab);
+       PL_regmatch_slab->prev = NULL;
+       PL_regmatch_slab->next = NULL;
+       PL_regmatch_state = SLAB_FIRST(PL_regmatch_slab);
+    }
+
+    oldsave = PL_savestack_ix;
+    SAVEDESTRUCTOR_X(S_clear_backtrack_stack, NULL);
+    SAVEVPTR(PL_regmatch_slab);
+    SAVEVPTR(PL_regmatch_state);
+
+    /* grab next free state slot */
+    st = ++PL_regmatch_state;
+    if (st >  SLAB_LAST(PL_regmatch_slab))
+       st = PL_regmatch_state = S_push_slab(aTHX);
+
+    /* Note that nextchr is a byte even in UTF */
+    nextchr = UCHARAT(locinput);
+    scan = prog;
+    while (scan != NULL) {
+
+        DEBUG_EXECUTE_r( {
+           SV * const prop = sv_newmortal();
+           regnode *rnext=regnext(scan);
+           DUMP_EXEC_POS( locinput, scan, do_utf8 );
+           regprop(rex, prop, scan);
+            
+           PerlIO_printf(Perl_debug_log,
+                   "%3"IVdf":%*s%s(%"IVdf")\n",
+                   (IV)(scan - rexi->program), depth*2, "",
+                   SvPVX_const(prop),
+                   (PL_regkind[OP(scan)] == END || !rnext) ? 
+                       0 : (IV)(rnext - rexi->program));
+       });
+
+       next = scan + NEXT_OFF(scan);
+       if (next == scan)
+           next = NULL;
+       state_num = OP(scan);
+
+       REH_CALL_EXEC_NODE_HOOK(rex, scan, reginfo, st);
+      reenter_switch:
+
+       assert(PL_reglastparen == &rex->lastparen);
+       assert(PL_reglastcloseparen == &rex->lastcloseparen);
+       assert(PL_regoffs == rex->offs);
+
+       switch (state_num) {
+       case BOL:
+           if (locinput == PL_bostr)
+           {
+               /* reginfo->till = reginfo->bol; */
+               break;
+           }
+           sayNO;
+       case MBOL:
+           if (locinput == PL_bostr ||
+               ((nextchr || locinput < PL_regeol) && locinput[-1] == '\n'))
+           {
+               break;
+           }
+           sayNO;
+       case SBOL:
+           if (locinput == PL_bostr)
+               break;
+           sayNO;
+       case GPOS:
+           if (locinput == reginfo->ganch)
+               break;
+           sayNO;
+
+       case KEEPS:
+           /* update the startpoint */
+           st->u.keeper.val = PL_regoffs[0].start;
+           PL_reginput = locinput;
+           PL_regoffs[0].start = locinput - PL_bostr;
+           PUSH_STATE_GOTO(KEEPS_next, next);
+           /*NOT-REACHED*/
+       case KEEPS_next_fail:
+           /* rollback the start point change */
+           PL_regoffs[0].start = st->u.keeper.val;
+           sayNO_SILENT;
+           /*NOT-REACHED*/
+       case EOL:
+               goto seol;
+       case MEOL:
+           if ((nextchr || locinput < PL_regeol) && nextchr != '\n')
+               sayNO;
+           break;
+       case SEOL:
+         seol:
+           if ((nextchr || locinput < PL_regeol) && nextchr != '\n')
+               sayNO;
+           if (PL_regeol - locinput > 1)
+               sayNO;
+           break;
+       case EOS:
+           if (PL_regeol != locinput)
+               sayNO;
+           break;
+       case SANY:
+           if (!nextchr && locinput >= PL_regeol)
+               sayNO;
+           if (do_utf8) {
+               locinput += PL_utf8skip[nextchr];
+               if (locinput > PL_regeol)
+                   sayNO;
+               nextchr = UCHARAT(locinput);
+           }
+           else
+               nextchr = UCHARAT(++locinput);
+           break;
+       case CANY:
+           if (!nextchr && locinput >= PL_regeol)
+               sayNO;
+           nextchr = UCHARAT(++locinput);
+           break;
+       case REG_ANY:
+           if ((!nextchr && locinput >= PL_regeol) || nextchr == '\n')
+               sayNO;
+           if (do_utf8) {
+               locinput += PL_utf8skip[nextchr];
+               if (locinput > PL_regeol)
+                   sayNO;
+               nextchr = UCHARAT(locinput);
+           }
+           else
+               nextchr = UCHARAT(++locinput);
+           break;
+
+#undef  ST
+#define ST st->u.trie
+        case TRIEC:
+            /* In this case the charclass data is available inline so
+               we can fail fast without a lot of extra overhead. 
+             */
+            if (scan->flags == EXACT || !do_utf8) {
+                if(!ANYOF_BITMAP_TEST(scan, *locinput)) {
+                    DEBUG_EXECUTE_r(
+                        PerlIO_printf(Perl_debug_log,
+                                 "%*s  %sfailed to match trie start class...%s\n",
+                                 REPORT_CODE_OFF+depth*2, "", PL_colors[4], PL_colors[5])
+                    );
+                    sayNO_SILENT;
+                    /* NOTREACHED */
+                }                      
+            }
+            /* FALL THROUGH */
+       case TRIE:
+           {
+                /* what type of TRIE am I? (utf8 makes this contextual) */
+                DECL_TRIE_TYPE(scan);
+
+                /* what trie are we using right now */
+               reg_trie_data * const trie
+                   = (reg_trie_data*)rexi->data->data[ ARG( scan ) ];
+               HV * widecharmap = MUTABLE_HV(rexi->data->data[ ARG( scan ) + 1 ]);
+                U32 state = trie->startstate;
+
+               if (trie->bitmap && trie_type != trie_utf8_fold &&
+                   !TRIE_BITMAP_TEST(trie,*locinput)
+               ) {
+                   if (trie->states[ state ].wordnum) {
+                        DEBUG_EXECUTE_r(
+                            PerlIO_printf(Perl_debug_log,
+                                         "%*s  %smatched empty string...%s\n",
+                                         REPORT_CODE_OFF+depth*2, "", PL_colors[4], PL_colors[5])
+                        );
+                       break;
+                   } else {
+                       DEBUG_EXECUTE_r(
+                            PerlIO_printf(Perl_debug_log,
+                                         "%*s  %sfailed to match trie start class...%s\n",
+                                         REPORT_CODE_OFF+depth*2, "", PL_colors[4], PL_colors[5])
+                        );
+                       sayNO_SILENT;
+                  }
+                }
+
+            { 
+               U8 *uc = ( U8* )locinput;
+
+               STRLEN len = 0;
+               STRLEN foldlen = 0;
+               U8 *uscan = (U8*)NULL;
+               STRLEN bufflen=0;
+               SV *sv_accept_buff = NULL;
+               U8 foldbuf[ UTF8_MAXBYTES_CASE + 1 ];
+
+               ST.accepted = 0; /* how many accepting states we have seen */
+               ST.B = next;
+               ST.jump = trie->jump;
+               ST.me = scan;
+               /*
+                  traverse the TRIE keeping track of all accepting states
+                  we transition through until we get to a failing node.
+               */
+
+               while ( state && uc <= (U8*)PL_regeol ) {
+                    U32 base = trie->states[ state ].trans.base;
+                    UV uvc = 0;
+                    U16 charid;
+                    /* We use charid to hold the wordnum as we don't use it
+                       for charid until after we have done the wordnum logic. 
+                       We define an alias just so that the wordnum logic reads
+                       more naturally. */
+
+#define got_wordnum charid
+                    got_wordnum = trie->states[ state ].wordnum;
+
+                   if ( got_wordnum ) {
+                       if ( ! ST.accepted ) {
+                           ENTER;
+                           SAVETMPS; /* XXX is this necessary? dmq */
+                           bufflen = TRIE_INITAL_ACCEPT_BUFFLEN;
+                           sv_accept_buff=newSV(bufflen *
+                                           sizeof(reg_trie_accepted) - 1);
+                           SvCUR_set(sv_accept_buff, 0);
+                           SvPOK_on(sv_accept_buff);
+                           sv_2mortal(sv_accept_buff);
+                           SAVETMPS;
+                           ST.accept_buff =
+                               (reg_trie_accepted*)SvPV_nolen(sv_accept_buff );
+                       }
+                       do {
+                           if (ST.accepted >= bufflen) {
+                               bufflen *= 2;
+                               ST.accept_buff =(reg_trie_accepted*)
+                                   SvGROW(sv_accept_buff,
+                                       bufflen * sizeof(reg_trie_accepted));
+                           }
+                           SvCUR_set(sv_accept_buff,SvCUR(sv_accept_buff)
+                               + sizeof(reg_trie_accepted));
+
+
+                           ST.accept_buff[ST.accepted].wordnum = got_wordnum;
+                           ST.accept_buff[ST.accepted].endpos = uc;
+                           ++ST.accepted;
+                       } while (trie->nextword && (got_wordnum= trie->nextword[got_wordnum]));
+                   }
+#undef got_wordnum 
+
+                   DEBUG_TRIE_EXECUTE_r({
+                               DUMP_EXEC_POS( (char *)uc, scan, do_utf8 );
+                               PerlIO_printf( Perl_debug_log,
+                                   "%*s  %sState: %4"UVxf" Accepted: %4"UVxf" ",
+                                   2+depth * 2, "", PL_colors[4],
+                                   (UV)state, (UV)ST.accepted );
+                   });
+
+                   if ( base ) {
+                       REXEC_TRIE_READ_CHAR(trie_type, trie, widecharmap, uc,
+                                            uscan, len, uvc, charid, foldlen,
+                                            foldbuf, uniflags);
+
+                       if (charid &&
+                            (base + charid > trie->uniquecharcount )
+                            && (base + charid - 1 - trie->uniquecharcount
+                                   < trie->lasttrans)
+                            && trie->trans[base + charid - 1 -
+                                   trie->uniquecharcount].check == state)
+                       {
+                           state = trie->trans[base + charid - 1 -
+                               trie->uniquecharcount ].next;
+                       }
+                       else {
+                           state = 0;
+                       }
+                       uc += len;
+
+                   }
+                   else {
+                       state = 0;
+                   }
+                   DEBUG_TRIE_EXECUTE_r(
+                       PerlIO_printf( Perl_debug_log,
+                           "Charid:%3x CP:%4"UVxf" After State: %4"UVxf"%s\n",
+                           charid, uvc, (UV)state, PL_colors[5] );
+                   );
+               }
+               if (!ST.accepted )
+                  sayNO;
+
+               DEBUG_EXECUTE_r(
+                   PerlIO_printf( Perl_debug_log,
+                       "%*s  %sgot %"IVdf" possible matches%s\n",
+                       REPORT_CODE_OFF + depth * 2, "",
+                       PL_colors[4], (IV)ST.accepted, PL_colors[5] );
+               );
+           }}
+            goto trie_first_try; /* jump into the fail handler */
+           /* NOTREACHED */
+       case TRIE_next_fail: /* we failed - try next alterative */
+            if ( ST.jump) {
+                REGCP_UNWIND(ST.cp);
+               for (n = *PL_reglastparen; n > ST.lastparen; n--)
+                   PL_regoffs[n].end = -1;
+               *PL_reglastparen = n;
+           }
+          trie_first_try:
+            if (do_cutgroup) {
+                do_cutgroup = 0;
+                no_final = 0;
+            }
+
+            if ( ST.jump) {
+                ST.lastparen = *PL_reglastparen;
+               REGCP_SET(ST.cp);
+            }          
+           if ( ST.accepted == 1 ) {
+               /* only one choice left - just continue */
+               DEBUG_EXECUTE_r({
+                   AV *const trie_words
+                       = MUTABLE_AV(rexi->data->data[ARG(ST.me)+TRIE_WORDS_OFFSET]);
+                   SV ** const tmp = av_fetch( trie_words, 
+                       ST.accept_buff[ 0 ].wordnum-1, 0 );
+                   SV *sv= tmp ? sv_newmortal() : NULL;
+                   
+                   PerlIO_printf( Perl_debug_log,
+                       "%*s  %sonly one match left: #%d <%s>%s\n",
+                       REPORT_CODE_OFF+depth*2, "", PL_colors[4],
+                       ST.accept_buff[ 0 ].wordnum,
+                       tmp ? pv_pretty(sv, SvPV_nolen_const(*tmp), SvCUR(*tmp), 0, 
+                               PL_colors[0], PL_colors[1],
+                               (SvUTF8(*tmp) ? PERL_PV_ESCAPE_UNI : 0)
+                            ) 
+                       : "not compiled under -Dr",
+                       PL_colors[5] );
+               });
+               PL_reginput = (char *)ST.accept_buff[ 0 ].endpos;
+               /* in this case we free tmps/leave before we call regmatch
+                  as we wont be using accept_buff again. */
+               
+               locinput = PL_reginput;
+               nextchr = UCHARAT(locinput);
+               if ( !ST.jump || !ST.jump[ST.accept_buff[0].wordnum]) 
+                   scan = ST.B;
+               else
+                   scan = ST.me + ST.jump[ST.accept_buff[0].wordnum];
+               if (!has_cutgroup) {
+                   FREETMPS;
+                   LEAVE;
+                } else {
+                    ST.accepted--;
+                    PUSH_YES_STATE_GOTO(TRIE_next, scan);
+                }
+               
+               continue; /* execute rest of RE */
+           }
+           
+           if ( !ST.accepted-- ) {
+               DEBUG_EXECUTE_r({
+                   PerlIO_printf( Perl_debug_log,
+                       "%*s  %sTRIE failed...%s\n",
+                       REPORT_CODE_OFF+depth*2, "", 
+                       PL_colors[4],
+                       PL_colors[5] );
+               });
+               FREETMPS;
+               LEAVE;
+               sayNO_SILENT;
+               /*NOTREACHED*/
+           } 
+
+           /*
+              There are at least two accepting states left.  Presumably
+              the number of accepting states is going to be low,
+              typically two. So we simply scan through to find the one
+              with lowest wordnum.  Once we find it, we swap the last
+              state into its place and decrement the size. We then try to
+              match the rest of the pattern at the point where the word
+              ends. If we succeed, control just continues along the
+              regex; if we fail we return here to try the next accepting
+              state
+            */
+
+           {
+               U32 best = 0;
+               U32 cur;
+               for( cur = 1 ; cur <= ST.accepted ; cur++ ) {
+                   DEBUG_TRIE_EXECUTE_r(
+                       PerlIO_printf( Perl_debug_log,
+                           "%*s  %sgot %"IVdf" (%d) as best, looking at %"IVdf" (%d)%s\n",
+                           REPORT_CODE_OFF + depth * 2, "", PL_colors[4],
+                           (IV)best, ST.accept_buff[ best ].wordnum, (IV)cur,
+                           ST.accept_buff[ cur ].wordnum, PL_colors[5] );
+                   );
+
+                   if (ST.accept_buff[cur].wordnum <
+                           ST.accept_buff[best].wordnum)
+                       best = cur;
+               }
+
+               DEBUG_EXECUTE_r({
+                   AV *const trie_words
+                       = MUTABLE_AV(rexi->data->data[ARG(ST.me)+TRIE_WORDS_OFFSET]);
+                   SV ** const tmp = av_fetch( trie_words, 
+                       ST.accept_buff[ best ].wordnum - 1, 0 );
+                   regnode *nextop=(!ST.jump || !ST.jump[ST.accept_buff[best].wordnum]) ? 
+                                   ST.B : 
+                                   ST.me + ST.jump[ST.accept_buff[best].wordnum];    
+                   SV *sv= tmp ? sv_newmortal() : NULL;
+                   
+                   PerlIO_printf( Perl_debug_log, 
+                       "%*s  %strying alternation #%d <%s> at node #%d %s\n",
+                       REPORT_CODE_OFF+depth*2, "", PL_colors[4],
+                       ST.accept_buff[best].wordnum,
+                       tmp ? pv_pretty(sv, SvPV_nolen_const(*tmp), SvCUR(*tmp), 0, 
+                               PL_colors[0], PL_colors[1],
+                               (SvUTF8(*tmp) ? PERL_PV_ESCAPE_UNI : 0)
+                            ) : "not compiled under -Dr", 
+                           REG_NODE_NUM(nextop),
+                       PL_colors[5] );
+               });
+
+               if ( best<ST.accepted ) {
+                   reg_trie_accepted tmp = ST.accept_buff[ best ];
+                   ST.accept_buff[ best ] = ST.accept_buff[ ST.accepted ];
+                   ST.accept_buff[ ST.accepted ] = tmp;
+                   best = ST.accepted;
+               }
+               PL_reginput = (char *)ST.accept_buff[ best ].endpos;
+               if ( !ST.jump || !ST.jump[ST.accept_buff[best].wordnum]) {
+                   scan = ST.B;
+               } else {
+                   scan = ST.me + ST.jump[ST.accept_buff[best].wordnum];
+                }
+                PUSH_YES_STATE_GOTO(TRIE_next, scan);    
+                /* NOTREACHED */
+           }
+           /* NOTREACHED */
+        case TRIE_next:
+           /* we dont want to throw this away, see bug 57042*/
+           if (oreplsv != GvSV(PL_replgv))
+               sv_setsv(oreplsv, GvSV(PL_replgv));
+            FREETMPS;
+           LEAVE;
+           sayYES;
+#undef  ST
+
+       case EXACT: {
+           char *s = STRING(scan);
+           ln = STR_LEN(scan);
+           if (do_utf8 != UTF) {
+               /* The target and the pattern have differing utf8ness. */
+               char *l = locinput;
+               const char * const e = s + ln;
+
+               if (do_utf8) {
+                   /* The target is utf8, the pattern is not utf8. */
+                   while (s < e) {
+                       STRLEN ulen;
+                       if (l >= PL_regeol)
+                            sayNO;
+                       if (NATIVE_TO_UNI(*(U8*)s) !=
+                           utf8n_to_uvuni((U8*)l, UTF8_MAXBYTES, &ulen,
+                                           uniflags))
+                            sayNO;
+                       l += ulen;
+                       s ++;
+                   }
+               }
+               else {
+                   /* The target is not utf8, the pattern is utf8. */
+                   while (s < e) {
+                       STRLEN ulen;
+                       if (l >= PL_regeol)
+                           sayNO;
+                       if (NATIVE_TO_UNI(*((U8*)l)) !=
+                           utf8n_to_uvuni((U8*)s, UTF8_MAXBYTES, &ulen,
+                                          uniflags))
+                           sayNO;
+                       s += ulen;
+                       l ++;
+                   }
+               }
+               locinput = l;
+               nextchr = UCHARAT(locinput);
+               break;
+           }
+           /* The target and the pattern have the same utf8ness. */
+           /* Inline the first character, for speed. */
+           if (UCHARAT(s) != nextchr)
+               sayNO;
+           if (PL_regeol - locinput < ln)
+               sayNO;
+           if (ln > 1 && memNE(s, locinput, ln))
+               sayNO;
+           locinput += ln;
+           nextchr = UCHARAT(locinput);
+           break;
+           }
+       case EXACTFL:
+           PL_reg_flags |= RF_tainted;
+           /* FALL THROUGH */
+       case EXACTF: {
+           char * const s = STRING(scan);
+           ln = STR_LEN(scan);
+
+           if (do_utf8 || UTF) {
+             /* Either target or the pattern are utf8. */
+               const char * const l = locinput;
+               char *e = PL_regeol;
+
+               if (ibcmp_utf8(s, 0,  ln, (bool)UTF,
+                              l, &e, 0,  do_utf8)) {
+                    /* One more case for the sharp s:
+                     * pack("U0U*", 0xDF) =~ /ss/i,
+                     * the 0xC3 0x9F are the UTF-8
+                     * byte sequence for the U+00DF. */
+
+                    if (!(do_utf8 &&
+                          toLOWER(s[0]) == 's' &&
+                          ln >= 2 &&
+                          toLOWER(s[1]) == 's' &&
+                          (U8)l[0] == 0xC3 &&
+                          e - l >= 2 &&
+                          (U8)l[1] == 0x9F))
+                         sayNO;
+               }
+               locinput = e;
+               nextchr = UCHARAT(locinput);
+               break;
+           }
+
+           /* Neither the target and the pattern are utf8. */
+
+           /* Inline the first character, for speed. */
+           if (UCHARAT(s) != nextchr &&
+               UCHARAT(s) != ((OP(scan) == EXACTF)
+                              ? PL_fold : PL_fold_locale)[nextchr])
+               sayNO;
+           if (PL_regeol - locinput < ln)
+               sayNO;
+           if (ln > 1 && (OP(scan) == EXACTF
+                          ? ibcmp(s, locinput, ln)
+                          : ibcmp_locale(s, locinput, ln)))
+               sayNO;
+           locinput += ln;
+           nextchr = UCHARAT(locinput);
+           break;
+           }
+       case BOUNDL:
+       case NBOUNDL:
+           PL_reg_flags |= RF_tainted;
+           /* FALL THROUGH */
+       case BOUND:
+       case NBOUND:
+           /* was last char in word? */
+           if (do_utf8) {
+               if (locinput == PL_bostr)
+                   ln = '\n';
+               else {
+                   const U8 * const r = reghop3((U8*)locinput, -1, (U8*)PL_bostr);
+
+                   ln = utf8n_to_uvchr(r, UTF8SKIP(r), 0, uniflags);
+               }
+               if (OP(scan) == BOUND || OP(scan) == NBOUND) {
+                   ln = isALNUM_uni(ln);
+                   LOAD_UTF8_CHARCLASS_ALNUM();
+                   n = swash_fetch(PL_utf8_alnum, (U8*)locinput, do_utf8);
+               }
+               else {
+                   ln = isALNUM_LC_uvchr(UNI_TO_NATIVE(ln));
+                   n = isALNUM_LC_utf8((U8*)locinput);
+               }
+           }
+           else {
+               ln = (locinput != PL_bostr) ?
+                   UCHARAT(locinput - 1) : '\n';
+               if (OP(scan) == BOUND || OP(scan) == NBOUND) {
+                   ln = isALNUM(ln);
+                   n = isALNUM(nextchr);
+               }
+               else {
+                   ln = isALNUM_LC(ln);
+                   n = isALNUM_LC(nextchr);
+               }
+           }
+           if (((!ln) == (!n)) == (OP(scan) == BOUND ||
+                                   OP(scan) == BOUNDL))
+                   sayNO;
+           break;
+       case ANYOF:
+           if (do_utf8) {
+               STRLEN inclasslen = PL_regeol - locinput;
+
+               if (!reginclass(rex, scan, (U8*)locinput, &inclasslen, do_utf8))
+                   goto anyof_fail;
+               if (locinput >= PL_regeol)
+                   sayNO;
+               locinput += inclasslen ? inclasslen : UTF8SKIP(locinput);
+               nextchr = UCHARAT(locinput);
+               break;
+           }
+           else {
+               if (nextchr < 0)
+                   nextchr = UCHARAT(locinput);
+               if (!REGINCLASS(rex, scan, (U8*)locinput))
+                   goto anyof_fail;
+               if (!nextchr && locinput >= PL_regeol)
+                   sayNO;
+               nextchr = UCHARAT(++locinput);
+               break;
+           }
+       anyof_fail:
+           /* If we might have the case of the German sharp s
+            * in a casefolding Unicode character class. */
+
+           if (ANYOF_FOLD_SHARP_S(scan, locinput, PL_regeol)) {
+                locinput += SHARP_S_SKIP;
+                nextchr = UCHARAT(locinput);
+           }
+           else
+                sayNO;
+           break;
+       /* Special char classes - The defines start on line 129 or so */
+       CCC_TRY_AFF( ALNUM,  ALNUML, perl_word,   "a", isALNUM_LC_utf8, isALNUM, isALNUM_LC);
+       CCC_TRY_NEG(NALNUM, NALNUML, perl_word,   "a", isALNUM_LC_utf8, isALNUM, isALNUM_LC);
+
+       CCC_TRY_AFF( SPACE,  SPACEL, perl_space,  " ", isSPACE_LC_utf8, isSPACE, isSPACE_LC);
+       CCC_TRY_NEG(NSPACE, NSPACEL, perl_space,  " ", isSPACE_LC_utf8, isSPACE, isSPACE_LC);
+
+       CCC_TRY_AFF( DIGIT,  DIGITL, posix_digit, "0", isDIGIT_LC_utf8, isDIGIT, isDIGIT_LC);
+       CCC_TRY_NEG(NDIGIT, NDIGITL, posix_digit, "0", isDIGIT_LC_utf8, isDIGIT, isDIGIT_LC);
+
+       case CLUMP: /* Match \X: logical Unicode character.  This is defined as
+                      a Unicode extended Grapheme Cluster */
+           /* From http://www.unicode.org/reports/tr29 (5.2 version).  An
+             extended Grapheme Cluster is:
+
+              CR LF
+              | Prepend* Begin Extend*
+              | .
+
+              Begin is (Hangul-syllable | ! Control)
+              Extend is (Grapheme_Extend | Spacing_Mark)
+              Control is [ GCB_Control CR LF ]
+
+              The discussion below shows how the code for CLUMP is derived
+              from this regex.  Note that most of these concepts are from
+              property values of the Grapheme Cluster Boundary (GCB) property.
+              No code point can have multiple property values for a given
+              property.  Thus a code point in Prepend can't be in Control, but
+              it must be in !Control.  This is why Control above includes
+              GCB_Control plus CR plus LF.  The latter two are used in the GCB
+              property separately, and so can't be in GCB_Control, even though
+              they logically are controls.  Control is not the same as gc=cc,
+              but includes format and other characters as well.
+
+              The Unicode definition of Hangul-syllable is:
+                  L+
+                  | (L* ( ( V | LV ) V* | LVT ) T*)
+                  | T+ 
+                 )
+              Each of these is a value for the GCB property, and hence must be
+              disjoint, so the order they are tested is immaterial, so the
+              above can safely be changed to
+                  T+
+                  | L+
+                  | (L* ( LVT | ( V | LV ) V*) T*)
+
+              The last two terms can be combined like this:
+                  L* ( L
+                       | (( LVT | ( V | LV ) V*) T*))
+
+              And refactored into this:
+                  L* (L | LVT T* | V  V* T* | LV  V* T*)
+
+              That means that if we have seen any L's at all we can quit
+              there, but if the next character is a LVT, a V or and LV we
+              should keep going.
+
+              There is a subtlety with Prepend* which showed up in testing.
+              Note that the Begin, and only the Begin is required in:
+               | Prepend* Begin Extend*
+              Also, Begin contains '! Control'.  A Prepend must be a '!
+              Control', which means it must be a Begin.  What it comes down to
+              is that if we match Prepend* and then find no suitable Begin
+              afterwards, that if we backtrack the last Prepend, that one will
+              be a suitable Begin.
+           */
+
+           if (locinput >= PL_regeol)
+               sayNO;
+           if  (! do_utf8) {
+
+               /* Match either CR LF  or '.', as all the other possibilities
+                * require utf8 */
+               locinput++;         /* Match the . or CR */
+               if (nextchr == '\r'
+                   && locinput < PL_regeol
+                   && UCHARAT(locinput) == '\n') locinput++;
+           }
+           else {
+
+               /* Utf8: See if is ( CR LF ); already know that locinput <
+                * PL_regeol, so locinput+1 is in bounds */
+               if (nextchr == '\r' && UCHARAT(locinput + 1) == '\n') {
+                   locinput += 2;
+               }
+               else {
+                   /* In case have to backtrack to beginning, then match '.' */
+                   char *starting = locinput;
+
+                   /* In case have to backtrack the last prepend */
+                   char *previous_prepend = 0;
+
+                   LOAD_UTF8_CHARCLASS_GCB();
+
+                   /* Match (prepend)* */
+                   while (locinput < PL_regeol
+                          && swash_fetch(PL_utf8_X_prepend,
+                                         (U8*)locinput, do_utf8))
+                   {
+                       previous_prepend = locinput;
+                       locinput += UTF8SKIP(locinput);
+                   }
+
+                   /* As noted above, if we matched a prepend character, but
+                    * the next thing won't match, back off the last prepend we
+                    * matched, as it is guaranteed to match the begin */
+                   if (previous_prepend
+                       && (locinput >=  PL_regeol
+                           || ! swash_fetch(PL_utf8_X_begin,
+                                            (U8*)locinput, do_utf8)))
+                   {
+                       locinput = previous_prepend;
+                   }
+
+                   /* Note that here we know PL_regeol > locinput, as we
+                    * tested that upon input to this switch case, and if we
+                    * moved locinput forward, we tested the result just above
+                    * and it either passed, or we backed off so that it will
+                    * now pass */
+                   if (! swash_fetch(PL_utf8_X_begin, (U8*)locinput, do_utf8)) {
+
+                       /* Here did not match the required 'Begin' in the
+                        * second term.  So just match the very first
+                        * character, the '.' of the final term of the regex */
+                       locinput = starting + UTF8SKIP(starting);
+                   } else {
+
+                       /* Here is the beginning of a character that can have
+                        * an extender.  It is either a hangul syllable, or a
+                        * non-control */
+                       if (swash_fetch(PL_utf8_X_non_hangul,
+                                       (U8*)locinput, do_utf8))
+                       {
+
+                           /* Here not a Hangul syllable, must be a
+                            * ('!  * Control') */
+                           locinput += UTF8SKIP(locinput);
+                       } else {
+
+                           /* Here is a Hangul syllable.  It can be composed
+                            * of several individual characters.  One
+                            * possibility is T+ */
+                           if (swash_fetch(PL_utf8_X_T,
+                                           (U8*)locinput, do_utf8))
+                           {
+                               while (locinput < PL_regeol
+                                       && swash_fetch(PL_utf8_X_T,
+                                                       (U8*)locinput, do_utf8))
+                               {
+                                   locinput += UTF8SKIP(locinput);
+                               }
+                           } else {
+
+                               /* Here, not T+, but is a Hangul.  That means
+                                * it is one of the others: L, LV, LVT or V,
+                                * and matches:
+                                * L* (L | LVT T* | V  V* T* | LV  V* T*) */
+
+                               /* Match L*           */
+                               while (locinput < PL_regeol
+                                       && swash_fetch(PL_utf8_X_L,
+                                                       (U8*)locinput, do_utf8))
+                               {
+                                   locinput += UTF8SKIP(locinput);
+                               }
+
+                               /* Here, have exhausted L*.  If the next
+                                * character is not an LV, LVT nor V, it means
+                                * we had to have at least one L, so matches L+
+                                * in the original equation, we have a complete
+                                * hangul syllable.  Are done. */
+
+                               if (locinput < PL_regeol
+                                   && swash_fetch(PL_utf8_X_LV_LVT_V,
+                                                   (U8*)locinput, do_utf8))
+                               {
+
+                                   /* Otherwise keep going.  Must be LV, LVT
+                                    * or V.  See if LVT */
+                                   if (swash_fetch(PL_utf8_X_LVT,
+                                                   (U8*)locinput, do_utf8))
+                                   {
+                                       locinput += UTF8SKIP(locinput);
+                                   } else {
+
+                                       /* Must be  V or LV.  Take it, then
+                                        * match V*     */
+                                       locinput += UTF8SKIP(locinput);
+                                       while (locinput < PL_regeol
+                                               && swash_fetch(PL_utf8_X_V,
+                                                        (U8*)locinput, do_utf8))
+                                       {
+                                           locinput += UTF8SKIP(locinput);
+                                       }
+                                   }
+
+                                   /* And any of LV, LVT, or V can be followed
+                                    * by T*            */
+                                   while (locinput < PL_regeol
+                                          && swash_fetch(PL_utf8_X_T,
+                                                          (U8*)locinput,
+                                                          do_utf8))
+                                   {
+                                       locinput += UTF8SKIP(locinput);
+                                   }
+                               }
+                           }
+                       }
+
+                       /* Match any extender */
+                       while (locinput < PL_regeol
+                               && swash_fetch(PL_utf8_X_extend,
+                                               (U8*)locinput, do_utf8))
+                       {
+                           locinput += UTF8SKIP(locinput);
+                       }
+                   }
+               }
+               if (locinput > PL_regeol) sayNO;
+           }
+           nextchr = UCHARAT(locinput);
+           break;
+            
+       case NREFFL:
+       {
+           char *s;
+           char type;
+           PL_reg_flags |= RF_tainted;
+           /* FALL THROUGH */
+       case NREF:
+       case NREFF:
+           type = OP(scan);
+           n = reg_check_named_buff_matched(rex,scan);
+
+            if ( n ) {
+                type = REF + ( type - NREF );
+                goto do_ref;
+            } else {
+                sayNO;
+            }
+            /* unreached */
+       case REFFL:
+           PL_reg_flags |= RF_tainted;
+           /* FALL THROUGH */
+        case REF:
+       case REFF: 
+           n = ARG(scan);  /* which paren pair */
+           type = OP(scan);
+         do_ref:  
+           ln = PL_regoffs[n].start;
+           PL_reg_leftiter = PL_reg_maxiter;           /* Void cache */
+           if (*PL_reglastparen < n || ln == -1)
+               sayNO;                  /* Do not match unless seen CLOSEn. */
+           if (ln == PL_regoffs[n].end)
+               break;
+
+           s = PL_bostr + ln;
+           if (do_utf8 && type != REF) {       /* REF can do byte comparison */
+               char *l = locinput;
+               const char *e = PL_bostr + PL_regoffs[n].end;
+               /*
+                * Note that we can't do the "other character" lookup trick as
+                * in the 8-bit case (no pun intended) because in Unicode we
+                * have to map both upper and title case to lower case.
+                */
+               if (type == REFF) {
+                   while (s < e) {
+                       STRLEN ulen1, ulen2;
+                       U8 tmpbuf1[UTF8_MAXBYTES_CASE+1];
+                       U8 tmpbuf2[UTF8_MAXBYTES_CASE+1];
+
+                       if (l >= PL_regeol)
+                           sayNO;
+                       toLOWER_utf8((U8*)s, tmpbuf1, &ulen1);
+                       toLOWER_utf8((U8*)l, tmpbuf2, &ulen2);
+                       if (ulen1 != ulen2 || memNE((char *)tmpbuf1, (char *)tmpbuf2, ulen1))
+                           sayNO;
+                       s += ulen1;
+                       l += ulen2;
+                   }
+               }
+               locinput = l;
+               nextchr = UCHARAT(locinput);
+               break;
+           }
+
+           /* Inline the first character, for speed. */
+           if (UCHARAT(s) != nextchr &&
+               (type == REF ||
+                (UCHARAT(s) != (type == REFF
+                                 ? PL_fold : PL_fold_locale)[nextchr])))
+               sayNO;
+           ln = PL_regoffs[n].end - ln;
+           if (locinput + ln > PL_regeol)
+               sayNO;
+           if (ln > 1 && (type == REF
+                          ? memNE(s, locinput, ln)
+                          : (type == REFF
+                             ? ibcmp(s, locinput, ln)
+                             : ibcmp_locale(s, locinput, ln))))
+               sayNO;
+           locinput += ln;
+           nextchr = UCHARAT(locinput);
+           break;
+       }
+       case NOTHING:
+       case TAIL:
+           break;
+       case BACK:
+           break;
+
+#undef  ST
+#define ST st->u.eval
+       {
+           SV *ret;
+           REGEXP *re_sv;
+            regexp *re;
+            regexp_internal *rei;
+            regnode *startpoint;
+
+       case GOSTART:
+       case GOSUB: /*    /(...(?1))/   /(...(?&foo))/   */
+           if (cur_eval && cur_eval->locinput==locinput) {
+                if (cur_eval->u.eval.close_paren == (U32)ARG(scan)) 
+                    Perl_croak(aTHX_ "Infinite recursion in regex");
+                if ( ++nochange_depth > max_nochange_depth )
+                    Perl_croak(aTHX_ 
+                        "Pattern subroutine nesting without pos change"
+                        " exceeded limit in regex");
+            } else {
+                nochange_depth = 0;
+            }
+           re_sv = rex_sv;
+            re = rex;
+            rei = rexi;
+            (void)ReREFCNT_inc(rex_sv);
+            if (OP(scan)==GOSUB) {
+                startpoint = scan + ARG2L(scan);
+                ST.close_paren = ARG(scan);
+            } else {
+                startpoint = rei->program+1;
+                ST.close_paren = 0;
+            }
+            goto eval_recurse_doit;
+            /* NOTREACHED */
+        case EVAL:  /*   /(?{A})B/   /(??{A})B/  and /(?(?{A})X|Y)B/   */        
+            if (cur_eval && cur_eval->locinput==locinput) {
+               if ( ++nochange_depth > max_nochange_depth )
+                    Perl_croak(aTHX_ "EVAL without pos change exceeded limit in regex");
+            } else {
+                nochange_depth = 0;
+            }    
+           {
+               /* execute the code in the {...} */
+               dSP;
+               SV ** const before = SP;
+               OP_4tree * const oop = PL_op;
+               COP * const ocurcop = PL_curcop;
+               PAD *old_comppad;
+               char *saved_regeol = PL_regeol;
+           
+               n = ARG(scan);
+               PL_op = (OP_4tree*)rexi->data->data[n];
+               DEBUG_STATE_r( PerlIO_printf(Perl_debug_log, 
+                   "  re_eval 0x%"UVxf"\n", PTR2UV(PL_op)) );
+               PAD_SAVE_LOCAL(old_comppad, (PAD*)rexi->data->data[n + 2]);
+               PL_regoffs[0].end = PL_reg_magic->mg_len = locinput - PL_bostr;
+
+                if (sv_yes_mark) {
+                    SV *sv_mrk = get_sv("REGMARK", 1);
+                    sv_setsv(sv_mrk, sv_yes_mark);
+                }
+
+               CALLRUNOPS(aTHX);                       /* Scalar context. */
+               SPAGAIN;
+               if (SP == before)
+                   ret = &PL_sv_undef;   /* protect against empty (?{}) blocks. */
+               else {
+                   ret = POPs;
+                   PUTBACK;
+               }
+
+               PL_op = oop;
+               PAD_RESTORE_LOCAL(old_comppad);
+               PL_curcop = ocurcop;
+               PL_regeol = saved_regeol;
+               if (!logical) {
+                   /* /(?{...})/ */
+                   sv_setsv(save_scalar(PL_replgv), ret);
+                   break;
+               }
+           }
+           if (logical == 2) { /* Postponed subexpression: /(??{...})/ */
+               logical = 0;
+               {
+                   /* extract RE object from returned value; compiling if
+                    * necessary */
+                   MAGIC *mg = NULL;
+                   REGEXP *rx = NULL;
+
+                   if (SvROK(ret)) {
+                       SV *const sv = SvRV(ret);
+
+                       if (SvTYPE(sv) == SVt_REGEXP) {
+                           rx = (REGEXP*) sv;
+                       } else if (SvSMAGICAL(sv)) {
+                           mg = mg_find(sv, PERL_MAGIC_qr);
+                           assert(mg);
+                       }
+                   } else if (SvTYPE(ret) == SVt_REGEXP) {
+                       rx = (REGEXP*) ret;
+                   } else if (SvSMAGICAL(ret)) {
+                       if (SvGMAGICAL(ret)) {
+                           /* I don't believe that there is ever qr magic
+                              here.  */
+                           assert(!mg_find(ret, PERL_MAGIC_qr));
+                           sv_unmagic(ret, PERL_MAGIC_qr);
+                       }
+                       else {
+                           mg = mg_find(ret, PERL_MAGIC_qr);
+                           /* testing suggests mg only ends up non-NULL for
+                              scalars who were upgraded and compiled in the
+                              else block below. In turn, this is only
+                              triggered in the "postponed utf8 string" tests
+                              in t/op/pat.t  */
+                       }
+                   }
+
+                   if (mg) {
+                       rx = (REGEXP *) mg->mg_obj; /*XXX:dmq*/
+                       assert(rx);
+                   }
+                   if (rx) {
+                       rx = reg_temp_copy(NULL, rx);
+                   }
+                   else {
+                       U32 pm_flags = 0;
+                       const I32 osize = PL_regsize;
+
+                       if (DO_UTF8(ret)) {
+                           assert (SvUTF8(ret));
+                       } else if (SvUTF8(ret)) {
+                           /* Not doing UTF-8, despite what the SV says. Is
+                              this only if we're trapped in use 'bytes'?  */
+                           /* Make a copy of the octet sequence, but without
+                              the flag on, as the compiler now honours the
+                              SvUTF8 flag on ret.  */
+                           STRLEN len;
+                           const char *const p = SvPV(ret, len);
+                           ret = newSVpvn_flags(p, len, SVs_TEMP);
+                       }
+                       rx = CALLREGCOMP(ret, pm_flags);
+                       if (!(SvFLAGS(ret)
+                             & (SVs_TEMP | SVs_PADTMP | SVf_READONLY
+                                | SVs_GMG))) {
+                           /* This isn't a first class regexp. Instead, it's
+                              caching a regexp onto an existing, Perl visible
+                              scalar.  */
+                           sv_magic(ret, MUTABLE_SV(rx), PERL_MAGIC_qr, 0, 0);
+                       }
+                       PL_regsize = osize;
+                   }
+                   re_sv = rx;
+                   re = (struct regexp *)SvANY(rx);
+               }
+                RXp_MATCH_COPIED_off(re);
+                re->subbeg = rex->subbeg;
+                re->sublen = rex->sublen;
+               rei = RXi_GET(re);
+                DEBUG_EXECUTE_r(
+                    debug_start_match(re_sv, do_utf8, locinput, PL_regeol, 
+                        "Matching embedded");
+               );              
+               startpoint = rei->program + 1;
+                       ST.close_paren = 0; /* only used for GOSUB */
+                       /* borrowed from regtry */
+                if (PL_reg_start_tmpl <= re->nparens) {
+                    PL_reg_start_tmpl = re->nparens*3/2 + 3;
+                    if(PL_reg_start_tmp)
+                        Renew(PL_reg_start_tmp, PL_reg_start_tmpl, char*);
+                    else
+                        Newx(PL_reg_start_tmp, PL_reg_start_tmpl, char*);
+                }                      
+
+        eval_recurse_doit: /* Share code with GOSUB below this line */                         
+               /* run the pattern returned from (??{...}) */
+               ST.cp = regcppush(0);   /* Save *all* the positions. */
+               REGCP_SET(ST.lastcp);
+               
+               PL_regoffs = re->offs; /* essentially NOOP on GOSUB */
+               
+               /* see regtry, specifically PL_reglast(?:close)?paren is a pointer! (i dont know why) :dmq */
+               PL_reglastparen = &re->lastparen;
+               PL_reglastcloseparen = &re->lastcloseparen;
+               re->lastparen = 0;
+               re->lastcloseparen = 0;
+
+               PL_reginput = locinput;
+               PL_regsize = 0;
+
+               /* XXXX This is too dramatic a measure... */
+               PL_reg_maxiter = 0;
+
+               ST.toggle_reg_flags = PL_reg_flags;
+               if (RX_UTF8(re_sv))
+                   PL_reg_flags |= RF_utf8;
+               else
+                   PL_reg_flags &= ~RF_utf8;
+               ST.toggle_reg_flags ^= PL_reg_flags; /* diff of old and new */
+
+               ST.prev_rex = rex_sv;
+               ST.prev_curlyx = cur_curlyx;
+               SETREX(rex_sv,re_sv);
+               rex = re;
+               rexi = rei;
+               cur_curlyx = NULL;
+               ST.B = next;
+               ST.prev_eval = cur_eval;
+               cur_eval = st;
+               /* now continue from first node in postoned RE */
+               PUSH_YES_STATE_GOTO(EVAL_AB, startpoint);
+               /* NOTREACHED */
+           }
+           /* logical is 1,   /(?(?{...})X|Y)/ */
+           sw = (bool)SvTRUE(ret);
+           logical = 0;
+           break;
+       }
+
+       case EVAL_AB: /* cleanup after a successful (??{A})B */
+           /* note: this is called twice; first after popping B, then A */
+           PL_reg_flags ^= ST.toggle_reg_flags; 
+           ReREFCNT_dec(rex_sv);
+           SETREX(rex_sv,ST.prev_rex);
+           rex = (struct regexp *)SvANY(rex_sv);
+           rexi = RXi_GET(rex);
+           regcpblow(ST.cp);
+           cur_eval = ST.prev_eval;
+           cur_curlyx = ST.prev_curlyx;
+
+           /* rex was changed so update the pointer in PL_reglastparen and PL_reglastcloseparen */
+           PL_reglastparen = &rex->lastparen;
+           PL_reglastcloseparen = &rex->lastcloseparen;
+           /* also update PL_regoffs */
+           PL_regoffs = rex->offs;
+           
+           /* XXXX This is too dramatic a measure... */
+           PL_reg_maxiter = 0;
+            if ( nochange_depth )
+               nochange_depth--;
+           sayYES;
+
+
+       case EVAL_AB_fail: /* unsuccessfully ran A or B in (??{A})B */
+           /* note: this is called twice; first after popping B, then A */
+           PL_reg_flags ^= ST.toggle_reg_flags; 
+           ReREFCNT_dec(rex_sv);
+           SETREX(rex_sv,ST.prev_rex);
+           rex = (struct regexp *)SvANY(rex_sv);
+           rexi = RXi_GET(rex); 
+           /* rex was changed so update the pointer in PL_reglastparen and PL_reglastcloseparen */
+           PL_reglastparen = &rex->lastparen;
+           PL_reglastcloseparen = &rex->lastcloseparen;
+
+           PL_reginput = locinput;
+           REGCP_UNWIND(ST.lastcp);
+           regcppop(rex);
+           cur_eval = ST.prev_eval;
+           cur_curlyx = ST.prev_curlyx;
+           /* XXXX This is too dramatic a measure... */
+           PL_reg_maxiter = 0;
+           if ( nochange_depth )
+               nochange_depth--;
+           sayNO_SILENT;
+#undef ST
+
+       case OPEN:
+           n = ARG(scan);  /* which paren pair */
+           PL_reg_start_tmp[n] = locinput;
+           if (n > PL_regsize)
+               PL_regsize = n;
+            lastopen = n;
+           break;
+       case CLOSE:
+           n = ARG(scan);  /* which paren pair */
+           PL_regoffs[n].start = PL_reg_start_tmp[n] - PL_bostr;
+           PL_regoffs[n].end = locinput - PL_bostr;
+           /*if (n > PL_regsize)
+               PL_regsize = n;*/
+           if (n > *PL_reglastparen)
+               *PL_reglastparen = n;
+           *PL_reglastcloseparen = n;
+            if (cur_eval && cur_eval->u.eval.close_paren == n) {
+               goto fake_end;
+           }    
+           break;
+        case ACCEPT:
+            if (ARG(scan)){
+                regnode *cursor;
+                for (cursor=scan;
+                     cursor && OP(cursor)!=END; 
+                     cursor=regnext(cursor)) 
+                {
+                    if ( OP(cursor)==CLOSE ){
+                        n = ARG(cursor);
+                        if ( n <= lastopen ) {
+                            PL_regoffs[n].start
+                               = PL_reg_start_tmp[n] - PL_bostr;
+                            PL_regoffs[n].end = locinput - PL_bostr;
+                            /*if (n > PL_regsize)
+                            PL_regsize = n;*/
+                            if (n > *PL_reglastparen)
+                                *PL_reglastparen = n;
+                            *PL_reglastcloseparen = n;
+                            if ( n == ARG(scan) || (cur_eval &&
+                                cur_eval->u.eval.close_paren == n))
+                                break;
+                        }
+                    }
+                }
+            }
+           goto fake_end;
+           /*NOTREACHED*/          
+       case GROUPP:
+           n = ARG(scan);  /* which paren pair */
+           sw = (bool)(*PL_reglastparen >= n && PL_regoffs[n].end != -1);
+           break;
+       case NGROUPP:
+           /* reg_check_named_buff_matched returns 0 for no match */
+           sw = (bool)(0 < reg_check_named_buff_matched(rex,scan));
+           break;
+        case INSUBP:
+            n = ARG(scan);
+            sw = (cur_eval && (!n || cur_eval->u.eval.close_paren == n));
+            break;
+        case DEFINEP:
+            sw = 0;
+            break;
+       case IFTHEN:
+           PL_reg_leftiter = PL_reg_maxiter;           /* Void cache */
+           if (sw)
+               next = NEXTOPER(NEXTOPER(scan));
+           else {
+               next = scan + ARG(scan);
+               if (OP(next) == IFTHEN) /* Fake one. */
+                   next = NEXTOPER(NEXTOPER(next));
+           }
+           break;
+       case LOGICAL:
+           logical = scan->flags;
+           break;
+
+/*******************************************************************
+
+The CURLYX/WHILEM pair of ops handle the most generic case of the /A*B/
+pattern, where A and B are subpatterns. (For simple A, CURLYM or
+STAR/PLUS/CURLY/CURLYN are used instead.)
+
+A*B is compiled as <CURLYX><A><WHILEM><B>
+
+On entry to the subpattern, CURLYX is called. This pushes a CURLYX
+state, which contains the current count, initialised to -1. It also sets
+cur_curlyx to point to this state, with any previous value saved in the
+state block.
+
+CURLYX then jumps straight to the WHILEM op, rather than executing A,
+since the pattern may possibly match zero times (i.e. it's a while {} loop
+rather than a do {} while loop).
+
+Each entry to WHILEM represents a successful match of A. The count in the
+CURLYX block is incremented, another WHILEM state is pushed, and execution
+passes to A or B depending on greediness and the current count.
+
+For example, if matching against the string a1a2a3b (where the aN are
+substrings that match /A/), then the match progresses as follows: (the
+pushed states are interspersed with the bits of strings matched so far):
+
+    <CURLYX cnt=-1>
+    <CURLYX cnt=0><WHILEM>
+    <CURLYX cnt=1><WHILEM> a1 <WHILEM>
+    <CURLYX cnt=2><WHILEM> a1 <WHILEM> a2 <WHILEM>
+    <CURLYX cnt=3><WHILEM> a1 <WHILEM> a2 <WHILEM> a3 <WHILEM>
+    <CURLYX cnt=3><WHILEM> a1 <WHILEM> a2 <WHILEM> a3 <WHILEM> b
+
+(Contrast this with something like CURLYM, which maintains only a single
+backtrack state:
+
+    <CURLYM cnt=0> a1
+    a1 <CURLYM cnt=1> a2
+    a1 a2 <CURLYM cnt=2> a3
+    a1 a2 a3 <CURLYM cnt=3> b
+)
+
+Each WHILEM state block marks a point to backtrack to upon partial failure
+of A or B, and also contains some minor state data related to that
+iteration.  The CURLYX block, pointed to by cur_curlyx, contains the
+overall state, such as the count, and pointers to the A and B ops.
+
+This is complicated slightly by nested CURLYX/WHILEM's. Since cur_curlyx
+must always point to the *current* CURLYX block, the rules are:
+
+When executing CURLYX, save the old cur_curlyx in the CURLYX state block,
+and set cur_curlyx to point the new block.
+
+When popping the CURLYX block after a successful or unsuccessful match,
+restore the previous cur_curlyx.
+
+When WHILEM is about to execute B, save the current cur_curlyx, and set it
+to the outer one saved in the CURLYX block.
+
+When popping the WHILEM block after a successful or unsuccessful B match,
+restore the previous cur_curlyx.
+
+Here's an example for the pattern (AI* BI)*BO
+I and O refer to inner and outer, C and W refer to CURLYX and WHILEM:
+
+cur_
+curlyx backtrack stack
+------ ---------------
+NULL   
+CO     <CO prev=NULL> <WO>
+CI     <CO prev=NULL> <WO> <CI prev=CO> <WI> ai 
+CO     <CO prev=NULL> <WO> <CI prev=CO> <WI> ai <WI prev=CI> bi 
+NULL   <CO prev=NULL> <WO> <CI prev=CO> <WI> ai <WI prev=CI> bi <WO prev=CO> bo
+
+At this point the pattern succeeds, and we work back down the stack to
+clean up, restoring as we go:
+
+CO     <CO prev=NULL> <WO> <CI prev=CO> <WI> ai <WI prev=CI> bi 
+CI     <CO prev=NULL> <WO> <CI prev=CO> <WI> ai 
+CO     <CO prev=NULL> <WO>
+NULL   
+
+*******************************************************************/
+
+#define ST st->u.curlyx
+
+       case CURLYX:    /* start of /A*B/  (for complex A) */
+       {
+           /* No need to save/restore up to this paren */
+           I32 parenfloor = scan->flags;
+           
+           assert(next); /* keep Coverity happy */
+           if (OP(PREVOPER(next)) == NOTHING) /* LONGJMP */
+               next += ARG(next);
+
+           /* XXXX Probably it is better to teach regpush to support
+              parenfloor > PL_regsize... */
+           if (parenfloor > (I32)*PL_reglastparen)
+               parenfloor = *PL_reglastparen; /* Pessimization... */
+
+           ST.prev_curlyx= cur_curlyx;
+           cur_curlyx = st;
+           ST.cp = PL_savestack_ix;
+
+           /* these fields contain the state of the current curly.
+            * they are accessed by subsequent WHILEMs */
+           ST.parenfloor = parenfloor;
+           ST.min = ARG1(scan);
+           ST.max = ARG2(scan);
+           ST.A = NEXTOPER(scan) + EXTRA_STEP_2ARGS;
+           ST.B = next;
+           ST.minmod = minmod;
+           minmod = 0;
+           ST.count = -1;      /* this will be updated by WHILEM */
+           ST.lastloc = NULL;  /* this will be updated by WHILEM */
+
+           PL_reginput = locinput;
+           PUSH_YES_STATE_GOTO(CURLYX_end, PREVOPER(next));
+           /* NOTREACHED */
+       }
+
+       case CURLYX_end: /* just finished matching all of A*B */
+           cur_curlyx = ST.prev_curlyx;
+           sayYES;
+           /* NOTREACHED */
+
+       case CURLYX_end_fail: /* just failed to match all of A*B */
+           regcpblow(ST.cp);
+           cur_curlyx = ST.prev_curlyx;
+           sayNO;
+           /* NOTREACHED */
+
+
+#undef ST
+#define ST st->u.whilem
+
+       case WHILEM:     /* just matched an A in /A*B/  (for complex A) */
+       {
+           /* see the discussion above about CURLYX/WHILEM */
+           I32 n;
+           assert(cur_curlyx); /* keep Coverity happy */
+           n = ++cur_curlyx->u.curlyx.count; /* how many A's matched */
+           ST.save_lastloc = cur_curlyx->u.curlyx.lastloc;
+           ST.cache_offset = 0;
+           ST.cache_mask = 0;
+           
+           PL_reginput = locinput;
+
+           DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
+                 "%*s  whilem: matched %ld out of %ld..%ld\n",
+                 REPORT_CODE_OFF+depth*2, "", (long)n,
+                 (long)cur_curlyx->u.curlyx.min,
+                 (long)cur_curlyx->u.curlyx.max)
+           );
+
+           /* First just match a string of min A's. */
+
+           if (n < cur_curlyx->u.curlyx.min) {
+               cur_curlyx->u.curlyx.lastloc = locinput;
+               PUSH_STATE_GOTO(WHILEM_A_pre, cur_curlyx->u.curlyx.A);
+               /* NOTREACHED */
+           }
+
+           /* If degenerate A matches "", assume A done. */
+
+           if (locinput == cur_curlyx->u.curlyx.lastloc) {
+               DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
+                  "%*s  whilem: empty match detected, trying continuation...\n",
+                  REPORT_CODE_OFF+depth*2, "")
+               );
+               goto do_whilem_B_max;
+           }
+
+           /* super-linear cache processing */
+
+           if (scan->flags) {
+
+               if (!PL_reg_maxiter) {
+                   /* start the countdown: Postpone detection until we
+                    * know the match is not *that* much linear. */
+                   PL_reg_maxiter = (PL_regeol - PL_bostr + 1) * (scan->flags>>4);
+                   /* possible overflow for long strings and many CURLYX's */
+                   if (PL_reg_maxiter < 0)
+                       PL_reg_maxiter = I32_MAX;
+                   PL_reg_leftiter = PL_reg_maxiter;
+               }
+
+               if (PL_reg_leftiter-- == 0) {
+                   /* initialise cache */
+                   const I32 size = (PL_reg_maxiter + 7)/8;
+                   if (PL_reg_poscache) {
+                       if ((I32)PL_reg_poscache_size < size) {
+                           Renew(PL_reg_poscache, size, char);
+                           PL_reg_poscache_size = size;
+                       }
+                       Zero(PL_reg_poscache, size, char);
+                   }
+                   else {
+                       PL_reg_poscache_size = size;
+                       Newxz(PL_reg_poscache, size, char);
+                   }
+                   DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
+      "%swhilem: Detected a super-linear match, switching on caching%s...\n",
+                             PL_colors[4], PL_colors[5])
+                   );
+               }
+
+               if (PL_reg_leftiter < 0) {
+                   /* have we already failed at this position? */
+                   I32 offset, mask;
+                   offset  = (scan->flags & 0xf) - 1
+                               + (locinput - PL_bostr)  * (scan->flags>>4);
+                   mask    = 1 << (offset % 8);
+                   offset /= 8;
+                   if (PL_reg_poscache[offset] & mask) {
+                       DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
+                           "%*s  whilem: (cache) already tried at this position...\n",
+                           REPORT_CODE_OFF+depth*2, "")
+                       );
+                       sayNO; /* cache records failure */
+                   }
+                   ST.cache_offset = offset;
+                   ST.cache_mask   = mask;
+               }
+           }
+
+           /* Prefer B over A for minimal matching. */
+
+           if (cur_curlyx->u.curlyx.minmod) {
+               ST.save_curlyx = cur_curlyx;
+               cur_curlyx = cur_curlyx->u.curlyx.prev_curlyx;
+               ST.cp = regcppush(ST.save_curlyx->u.curlyx.parenfloor);
+               REGCP_SET(ST.lastcp);
+               PUSH_YES_STATE_GOTO(WHILEM_B_min, ST.save_curlyx->u.curlyx.B);
+               /* NOTREACHED */
+           }
+
+           /* Prefer A over B for maximal matching. */
+
+           if (n < cur_curlyx->u.curlyx.max) { /* More greed allowed? */
+               ST.cp = regcppush(cur_curlyx->u.curlyx.parenfloor);
+               cur_curlyx->u.curlyx.lastloc = locinput;
+               REGCP_SET(ST.lastcp);
+               PUSH_STATE_GOTO(WHILEM_A_max, cur_curlyx->u.curlyx.A);
+               /* NOTREACHED */
+           }
+           goto do_whilem_B_max;
+       }
+       /* NOTREACHED */
+
+       case WHILEM_B_min: /* just matched B in a minimal match */
+       case WHILEM_B_max: /* just matched B in a maximal match */
+           cur_curlyx = ST.save_curlyx;
+           sayYES;
+           /* NOTREACHED */
+
+       case WHILEM_B_max_fail: /* just failed to match B in a maximal match */
+           cur_curlyx = ST.save_curlyx;
+           cur_curlyx->u.curlyx.lastloc = ST.save_lastloc;
+           cur_curlyx->u.curlyx.count--;
+           CACHEsayNO;
+           /* NOTREACHED */
+
+       case WHILEM_A_min_fail: /* just failed to match A in a minimal match */
+           REGCP_UNWIND(ST.lastcp);
+           regcppop(rex);
+           /* FALL THROUGH */
+       case WHILEM_A_pre_fail: /* just failed to match even minimal A */
+           cur_curlyx->u.curlyx.lastloc = ST.save_lastloc;
+           cur_curlyx->u.curlyx.count--;
+           CACHEsayNO;
+           /* NOTREACHED */
+
+       case WHILEM_A_max_fail: /* just failed to match A in a maximal match */
+           REGCP_UNWIND(ST.lastcp);
+           regcppop(rex);      /* Restore some previous $<digit>s? */
+           PL_reginput = locinput;
+           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+               "%*s  whilem: failed, trying continuation...\n",
+               REPORT_CODE_OFF+depth*2, "")
+           );
+         do_whilem_B_max:
+           if (cur_curlyx->u.curlyx.count >= REG_INFTY
+               && ckWARN(WARN_REGEXP)
+               && !(PL_reg_flags & RF_warned))
+           {
+               PL_reg_flags |= RF_warned;
+               Perl_warner(aTHX_ packWARN(WARN_REGEXP), "%s limit (%d) exceeded",
+                    "Complex regular subexpression recursion",
+                    REG_INFTY - 1);
+           }
+
+           /* now try B */
+           ST.save_curlyx = cur_curlyx;
+           cur_curlyx = cur_curlyx->u.curlyx.prev_curlyx;
+           PUSH_YES_STATE_GOTO(WHILEM_B_max, ST.save_curlyx->u.curlyx.B);
+           /* NOTREACHED */
+
+       case WHILEM_B_min_fail: /* just failed to match B in a minimal match */
+           cur_curlyx = ST.save_curlyx;
+           REGCP_UNWIND(ST.lastcp);
+           regcppop(rex);
+
+           if (cur_curlyx->u.curlyx.count >= cur_curlyx->u.curlyx.max) {
+               /* Maximum greed exceeded */
+               if (cur_curlyx->u.curlyx.count >= REG_INFTY
+                   && ckWARN(WARN_REGEXP)
+                   && !(PL_reg_flags & RF_warned))
+               {
+                   PL_reg_flags |= RF_warned;
+                   Perl_warner(aTHX_ packWARN(WARN_REGEXP),
+                       "%s limit (%d) exceeded",
+                       "Complex regular subexpression recursion",
+                       REG_INFTY - 1);
+               }
+               cur_curlyx->u.curlyx.count--;
+               CACHEsayNO;
+           }
+
+           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+               "%*s  trying longer...\n", REPORT_CODE_OFF+depth*2, "")
+           );
+           /* Try grabbing another A and see if it helps. */
+           PL_reginput = locinput;
+           cur_curlyx->u.curlyx.lastloc = locinput;
+           ST.cp = regcppush(cur_curlyx->u.curlyx.parenfloor);
+           REGCP_SET(ST.lastcp);
+           PUSH_STATE_GOTO(WHILEM_A_min, ST.save_curlyx->u.curlyx.A);
+           /* NOTREACHED */
+
+#undef  ST
+#define ST st->u.branch
+
+       case BRANCHJ:       /*  /(...|A|...)/ with long next pointer */
+           next = scan + ARG(scan);
+           if (next == scan)
+               next = NULL;
+           scan = NEXTOPER(scan);
+           /* FALL THROUGH */
+
+       case BRANCH:        /*  /(...|A|...)/ */
+           scan = NEXTOPER(scan); /* scan now points to inner node */
+           ST.lastparen = *PL_reglastparen;
+           ST.next_branch = next;
+           REGCP_SET(ST.cp);
+           PL_reginput = locinput;
+
+           /* Now go into the branch */
+           if (has_cutgroup) {
+               PUSH_YES_STATE_GOTO(BRANCH_next, scan);    
+           } else {
+               PUSH_STATE_GOTO(BRANCH_next, scan);
+           }
+           /* NOTREACHED */
+        case CUTGROUP:
+            PL_reginput = locinput;
+            sv_yes_mark = st->u.mark.mark_name = scan->flags ? NULL :
+                MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
+            PUSH_STATE_GOTO(CUTGROUP_next,next);
+            /* NOTREACHED */
+        case CUTGROUP_next_fail:
+            do_cutgroup = 1;
+            no_final = 1;
+            if (st->u.mark.mark_name)
+                sv_commit = st->u.mark.mark_name;
+            sayNO;         
+            /* NOTREACHED */
+        case BRANCH_next:
+            sayYES;
+            /* NOTREACHED */
+       case BRANCH_next_fail: /* that branch failed; try the next, if any */
+           if (do_cutgroup) {
+               do_cutgroup = 0;
+               no_final = 0;
+           }
+           REGCP_UNWIND(ST.cp);
+           for (n = *PL_reglastparen; n > ST.lastparen; n--)
+               PL_regoffs[n].end = -1;
+           *PL_reglastparen = n;
+           /*dmq: *PL_reglastcloseparen = n; */
+           scan = ST.next_branch;
+           /* no more branches? */
+           if (!scan || (OP(scan) != BRANCH && OP(scan) != BRANCHJ)) {
+               DEBUG_EXECUTE_r({
+                   PerlIO_printf( Perl_debug_log,
+                       "%*s  %sBRANCH failed...%s\n",
+                       REPORT_CODE_OFF+depth*2, "", 
+                       PL_colors[4],
+                       PL_colors[5] );
+               });
+               sayNO_SILENT;
+            }
+           continue; /* execute next BRANCH[J] op */
+           /* NOTREACHED */
+    
+       case MINMOD:
+           minmod = 1;
+           break;
+
+#undef  ST
+#define ST st->u.curlym
+
+       case CURLYM:    /* /A{m,n}B/ where A is fixed-length */
+
+           /* This is an optimisation of CURLYX that enables us to push
+            * only a single backtracking state, no matter how many matches
+            * there are in {m,n}. It relies on the pattern being constant
+            * length, with no parens to influence future backrefs
+            */
+
+           ST.me = scan;
+           scan = NEXTOPER(scan) + NODE_STEP_REGNODE;
+
+           /* if paren positive, emulate an OPEN/CLOSE around A */
+           if (ST.me->flags) {
+               U32 paren = ST.me->flags;
+               if (paren > PL_regsize)
+                   PL_regsize = paren;
+               if (paren > *PL_reglastparen)
+                   *PL_reglastparen = paren;
+               scan += NEXT_OFF(scan); /* Skip former OPEN. */
+           }
+           ST.A = scan;
+           ST.B = next;
+           ST.alen = 0;
+           ST.count = 0;
+           ST.minmod = minmod;
+           minmod = 0;
+           ST.c1 = CHRTEST_UNINIT;
+           REGCP_SET(ST.cp);
+
+           if (!(ST.minmod ? ARG1(ST.me) : ARG2(ST.me))) /* min/max */
+               goto curlym_do_B;
+
+         curlym_do_A: /* execute the A in /A{m,n}B/  */
+           PL_reginput = locinput;
+           PUSH_YES_STATE_GOTO(CURLYM_A, ST.A); /* match A */
+           /* NOTREACHED */
+
+       case CURLYM_A: /* we've just matched an A */
+           locinput = st->locinput;
+           nextchr = UCHARAT(locinput);
+
+           ST.count++;
+           /* after first match, determine A's length: u.curlym.alen */
+           if (ST.count == 1) {
+               if (PL_reg_match_utf8) {
+                   char *s = locinput;
+                   while (s < PL_reginput) {
+                       ST.alen++;
+                       s += UTF8SKIP(s);
+                   }
+               }
+               else {
+                   ST.alen = PL_reginput - locinput;
+               }
+               if (ST.alen == 0)
+                   ST.count = ST.minmod ? ARG1(ST.me) : ARG2(ST.me);
+           }
+           DEBUG_EXECUTE_r(
+               PerlIO_printf(Perl_debug_log,
+                         "%*s  CURLYM now matched %"IVdf" times, len=%"IVdf"...\n",
+                         (int)(REPORT_CODE_OFF+(depth*2)), "",
+                         (IV) ST.count, (IV)ST.alen)
+           );
+
+           locinput = PL_reginput;
+                       
+           if (cur_eval && cur_eval->u.eval.close_paren && 
+               cur_eval->u.eval.close_paren == (U32)ST.me->flags) 
+               goto fake_end;
+               
+           {
+               I32 max = (ST.minmod ? ARG1(ST.me) : ARG2(ST.me));
+               if ( max == REG_INFTY || ST.count < max )
+                   goto curlym_do_A; /* try to match another A */
+           }
+           goto curlym_do_B; /* try to match B */
+
+       case CURLYM_A_fail: /* just failed to match an A */
+           REGCP_UNWIND(ST.cp);
+
+           if (ST.minmod || ST.count < ARG1(ST.me) /* min*/ 
+               || (cur_eval && cur_eval->u.eval.close_paren &&
+                   cur_eval->u.eval.close_paren == (U32)ST.me->flags))
+               sayNO;
+
+         curlym_do_B: /* execute the B in /A{m,n}B/  */
+           PL_reginput = locinput;
+           if (ST.c1 == CHRTEST_UNINIT) {
+               /* calculate c1 and c2 for possible match of 1st char
+                * following curly */
+               ST.c1 = ST.c2 = CHRTEST_VOID;
+               if (HAS_TEXT(ST.B) || JUMPABLE(ST.B)) {
+                   regnode *text_node = ST.B;
+                   if (! HAS_TEXT(text_node))
+                       FIND_NEXT_IMPT(text_node);
+                   /* this used to be 
+                       
+                       (HAS_TEXT(text_node) && PL_regkind[OP(text_node)] == EXACT)
+                       
+                       But the former is redundant in light of the latter.
+                       
+                       if this changes back then the macro for 
+                       IS_TEXT and friends need to change.
+                    */
+                   if (PL_regkind[OP(text_node)] == EXACT)
+                   {
+                       
+                       ST.c1 = (U8)*STRING(text_node);
+                       ST.c2 =
+                           (IS_TEXTF(text_node))
+                           ? PL_fold[ST.c1]
+                           : (IS_TEXTFL(text_node))
+                               ? PL_fold_locale[ST.c1]
+                               : ST.c1;
+                   }
+               }
+           }
+
+           DEBUG_EXECUTE_r(
+               PerlIO_printf(Perl_debug_log,
+                   "%*s  CURLYM trying tail with matches=%"IVdf"...\n",
+                   (int)(REPORT_CODE_OFF+(depth*2)),
+                   "", (IV)ST.count)
+               );
+           if (ST.c1 != CHRTEST_VOID
+                   && UCHARAT(PL_reginput) != ST.c1
+                   && UCHARAT(PL_reginput) != ST.c2)
+           {
+               /* simulate B failing */
+               DEBUG_OPTIMISE_r(
+                   PerlIO_printf(Perl_debug_log,
+                       "%*s  CURLYM Fast bail c1=%"IVdf" c2=%"IVdf"\n",
+                       (int)(REPORT_CODE_OFF+(depth*2)),"",
+                       (IV)ST.c1,(IV)ST.c2
+               ));
+               state_num = CURLYM_B_fail;
+               goto reenter_switch;
+           }
+
+           if (ST.me->flags) {
+               /* mark current A as captured */
+               I32 paren = ST.me->flags;
+               if (ST.count) {
+                   PL_regoffs[paren].start
+                       = HOPc(PL_reginput, -ST.alen) - PL_bostr;
+                   PL_regoffs[paren].end = PL_reginput - PL_bostr;
+                   /*dmq: *PL_reglastcloseparen = paren; */
+               }
+               else
+                   PL_regoffs[paren].end = -1;
+               if (cur_eval && cur_eval->u.eval.close_paren &&
+                   cur_eval->u.eval.close_paren == (U32)ST.me->flags) 
+               {
+                   if (ST.count) 
+                       goto fake_end;
+                   else
+                       sayNO;
+               }
+           }
+           
+           PUSH_STATE_GOTO(CURLYM_B, ST.B); /* match B */
+           /* NOTREACHED */
+
+       case CURLYM_B_fail: /* just failed to match a B */
+           REGCP_UNWIND(ST.cp);
+           if (ST.minmod) {
+               I32 max = ARG2(ST.me);
+               if (max != REG_INFTY && ST.count == max)
+                   sayNO;
+               goto curlym_do_A; /* try to match a further A */
+           }
+           /* backtrack one A */
+           if (ST.count == ARG1(ST.me) /* min */)
+               sayNO;
+           ST.count--;
+           locinput = HOPc(locinput, -ST.alen);
+           goto curlym_do_B; /* try to match B */
+
+#undef ST
+#define ST st->u.curly
+
+#define CURLY_SETPAREN(paren, success) \
+    if (paren) { \
+       if (success) { \
+           PL_regoffs[paren].start = HOPc(locinput, -1) - PL_bostr; \
+           PL_regoffs[paren].end = locinput - PL_bostr; \
+           *PL_reglastcloseparen = paren; \
+       } \
+       else \
+           PL_regoffs[paren].end = -1; \
+    }
+
+       case STAR:              /*  /A*B/ where A is width 1 */
+           ST.paren = 0;
+           ST.min = 0;
+           ST.max = REG_INFTY;
+           scan = NEXTOPER(scan);
+           goto repeat;
+       case PLUS:              /*  /A+B/ where A is width 1 */
+           ST.paren = 0;
+           ST.min = 1;
+           ST.max = REG_INFTY;
+           scan = NEXTOPER(scan);
+           goto repeat;
+       case CURLYN:            /*  /(A){m,n}B/ where A is width 1 */
+           ST.paren = scan->flags;     /* Which paren to set */
+           if (ST.paren > PL_regsize)
+               PL_regsize = ST.paren;
+           if (ST.paren > *PL_reglastparen)
+               *PL_reglastparen = ST.paren;
+           ST.min = ARG1(scan);  /* min to match */
+           ST.max = ARG2(scan);  /* max to match */
+           if (cur_eval && cur_eval->u.eval.close_paren &&
+               cur_eval->u.eval.close_paren == (U32)ST.paren) {
+               ST.min=1;
+               ST.max=1;
+           }
+            scan = regnext(NEXTOPER(scan) + NODE_STEP_REGNODE);
+           goto repeat;
+       case CURLY:             /*  /A{m,n}B/ where A is width 1 */
+           ST.paren = 0;
+           ST.min = ARG1(scan);  /* min to match */
+           ST.max = ARG2(scan);  /* max to match */
+           scan = NEXTOPER(scan) + NODE_STEP_REGNODE;
+         repeat:
+           /*
+           * Lookahead to avoid useless match attempts
+           * when we know what character comes next.
+           *
+           * Used to only do .*x and .*?x, but now it allows
+           * for )'s, ('s and (?{ ... })'s to be in the way
+           * of the quantifier and the EXACT-like node.  -- japhy
+           */
+
+           if (ST.min > ST.max) /* XXX make this a compile-time check? */
+               sayNO;
+           if (HAS_TEXT(next) || JUMPABLE(next)) {
+               U8 *s;
+               regnode *text_node = next;
+
+               if (! HAS_TEXT(text_node)) 
+                   FIND_NEXT_IMPT(text_node);
+
+               if (! HAS_TEXT(text_node))
+                   ST.c1 = ST.c2 = CHRTEST_VOID;
+               else {
+                   if ( PL_regkind[OP(text_node)] != EXACT ) {
+                       ST.c1 = ST.c2 = CHRTEST_VOID;
+                       goto assume_ok_easy;
+                   }
+                   else
+                       s = (U8*)STRING(text_node);
+                    
+                    /*  Currently we only get here when 
+                        
+                        PL_rekind[OP(text_node)] == EXACT
+                    
+                        if this changes back then the macro for IS_TEXT and 
+                        friends need to change. */
+                   if (!UTF) {
+                       ST.c2 = ST.c1 = *s;
+                       if (IS_TEXTF(text_node))
+                           ST.c2 = PL_fold[ST.c1];
+                       else if (IS_TEXTFL(text_node))
+                           ST.c2 = PL_fold_locale[ST.c1];
+                   }
+                   else { /* UTF */
+                       if (IS_TEXTF(text_node)) {
+                            STRLEN ulen1, ulen2;
+                            U8 tmpbuf1[UTF8_MAXBYTES_CASE+1];
+                            U8 tmpbuf2[UTF8_MAXBYTES_CASE+1];
+
+                            to_utf8_lower((U8*)s, tmpbuf1, &ulen1);
+                            to_utf8_upper((U8*)s, tmpbuf2, &ulen2);
+#ifdef EBCDIC
+                            ST.c1 = utf8n_to_uvchr(tmpbuf1, UTF8_MAXLEN, 0,
+                                                   ckWARN(WARN_UTF8) ?
+                                                    0 : UTF8_ALLOW_ANY);
+                            ST.c2 = utf8n_to_uvchr(tmpbuf2, UTF8_MAXLEN, 0,
+                                                    ckWARN(WARN_UTF8) ?
+                                                    0 : UTF8_ALLOW_ANY);
+#else
+                            ST.c1 = utf8n_to_uvuni(tmpbuf1, UTF8_MAXBYTES, 0,
+                                                   uniflags);
+                            ST.c2 = utf8n_to_uvuni(tmpbuf2, UTF8_MAXBYTES, 0,
+                                                   uniflags);
+#endif
+                       }
+                       else {
+                           ST.c2 = ST.c1 = utf8n_to_uvchr(s, UTF8_MAXBYTES, 0,
+                                                    uniflags);
+                       }
+                   }
+               }
+           }
+           else
+               ST.c1 = ST.c2 = CHRTEST_VOID;
+       assume_ok_easy:
+
+           ST.A = scan;
+           ST.B = next;
+           PL_reginput = locinput;
+           if (minmod) {
+               minmod = 0;
+               if (ST.min && regrepeat(rex, ST.A, ST.min, depth) < ST.min)
+                   sayNO;
+               ST.count = ST.min;
+               locinput = PL_reginput;
+               REGCP_SET(ST.cp);
+               if (ST.c1 == CHRTEST_VOID)
+                   goto curly_try_B_min;
+
+               ST.oldloc = locinput;
+
+               /* set ST.maxpos to the furthest point along the
+                * string that could possibly match */
+               if  (ST.max == REG_INFTY) {
+                   ST.maxpos = PL_regeol - 1;
+                   if (do_utf8)
+                       while (UTF8_IS_CONTINUATION(*(U8*)ST.maxpos))
+                           ST.maxpos--;
+               }
+               else if (do_utf8) {
+                   int m = ST.max - ST.min;
+                   for (ST.maxpos = locinput;
+                        m >0 && ST.maxpos + UTF8SKIP(ST.maxpos) <= PL_regeol; m--)
+                       ST.maxpos += UTF8SKIP(ST.maxpos);
+               }
+               else {
+                   ST.maxpos = locinput + ST.max - ST.min;
+                   if (ST.maxpos >= PL_regeol)
+                       ST.maxpos = PL_regeol - 1;
+               }
+               goto curly_try_B_min_known;
+
+           }
+           else {
+               ST.count = regrepeat(rex, ST.A, ST.max, depth);
+               locinput = PL_reginput;
+               if (ST.count < ST.min)
+                   sayNO;
+               if ((ST.count > ST.min)
+                   && (PL_regkind[OP(ST.B)] == EOL) && (OP(ST.B) != MEOL))
+               {
+                   /* A{m,n} must come at the end of the string, there's
+                    * no point in backing off ... */
+                   ST.min = ST.count;
+                   /* ...except that $ and \Z can match before *and* after
+                      newline at the end.  Consider "\n\n" =~ /\n+\Z\n/.
+                      We may back off by one in this case. */
+                   if (UCHARAT(PL_reginput - 1) == '\n' && OP(ST.B) != EOS)
+                       ST.min--;
+               }
+               REGCP_SET(ST.cp);
+               goto curly_try_B_max;
+           }
+           /* NOTREACHED */
+
+
+       case CURLY_B_min_known_fail:
+           /* failed to find B in a non-greedy match where c1,c2 valid */
+           if (ST.paren && ST.count)
+               PL_regoffs[ST.paren].end = -1;
+
+           PL_reginput = locinput;     /* Could be reset... */
+           REGCP_UNWIND(ST.cp);
+           /* Couldn't or didn't -- move forward. */
+           ST.oldloc = locinput;
+           if (do_utf8)
+               locinput += UTF8SKIP(locinput);
+           else
+               locinput++;
+           ST.count++;
+         curly_try_B_min_known:
+            /* find the next place where 'B' could work, then call B */
+           {
+               int n;
+               if (do_utf8) {
+                   n = (ST.oldloc == locinput) ? 0 : 1;
+                   if (ST.c1 == ST.c2) {
+                       STRLEN len;
+                       /* set n to utf8_distance(oldloc, locinput) */
+                       while (locinput <= ST.maxpos &&
+                              utf8n_to_uvchr((U8*)locinput,
+                                             UTF8_MAXBYTES, &len,
+                                             uniflags) != (UV)ST.c1) {
+                           locinput += len;
+                           n++;
+                       }
+                   }
+                   else {
+                       /* set n to utf8_distance(oldloc, locinput) */
+                       while (locinput <= ST.maxpos) {
+                           STRLEN len;
+                           const UV c = utf8n_to_uvchr((U8*)locinput,
+                                                 UTF8_MAXBYTES, &len,
+                                                 uniflags);
+                           if (c == (UV)ST.c1 || c == (UV)ST.c2)
+                               break;
+                           locinput += len;
+                           n++;
+                       }
+                   }
+               }
+               else {
+                   if (ST.c1 == ST.c2) {
+                       while (locinput <= ST.maxpos &&
+                              UCHARAT(locinput) != ST.c1)
+                           locinput++;
+                   }
+                   else {
+                       while (locinput <= ST.maxpos
+                              && UCHARAT(locinput) != ST.c1
+                              && UCHARAT(locinput) != ST.c2)
+                           locinput++;
+                   }
+                   n = locinput - ST.oldloc;
+               }
+               if (locinput > ST.maxpos)
+                   sayNO;
+               /* PL_reginput == oldloc now */
+               if (n) {
+                   ST.count += n;
+                   if (regrepeat(rex, ST.A, n, depth) < n)
+                       sayNO;
+               }
+               PL_reginput = locinput;
+               CURLY_SETPAREN(ST.paren, ST.count);
+               if (cur_eval && cur_eval->u.eval.close_paren && 
+                   cur_eval->u.eval.close_paren == (U32)ST.paren) {
+                   goto fake_end;
+               }
+               PUSH_STATE_GOTO(CURLY_B_min_known, ST.B);
+           }
+           /* NOTREACHED */
+
+
+       case CURLY_B_min_fail:
+           /* failed to find B in a non-greedy match where c1,c2 invalid */
+           if (ST.paren && ST.count)
+               PL_regoffs[ST.paren].end = -1;
+
+           REGCP_UNWIND(ST.cp);
+           /* failed -- move forward one */
+           PL_reginput = locinput;
+           if (regrepeat(rex, ST.A, 1, depth)) {
+               ST.count++;
+               locinput = PL_reginput;
+               if (ST.count <= ST.max || (ST.max == REG_INFTY &&
+                       ST.count > 0)) /* count overflow ? */
+               {
+                 curly_try_B_min:
+                   CURLY_SETPAREN(ST.paren, ST.count);
+                   if (cur_eval && cur_eval->u.eval.close_paren &&
+                       cur_eval->u.eval.close_paren == (U32)ST.paren) {
+                        goto fake_end;
+                    }
+                   PUSH_STATE_GOTO(CURLY_B_min, ST.B);
+               }
+           }
+           sayNO;
+           /* NOTREACHED */
+
+
+       curly_try_B_max:
+           /* a successful greedy match: now try to match B */
+            if (cur_eval && cur_eval->u.eval.close_paren &&
+                cur_eval->u.eval.close_paren == (U32)ST.paren) {
+                goto fake_end;
+            }
+           {
+               UV c = 0;
+               if (ST.c1 != CHRTEST_VOID)
+                   c = do_utf8 ? utf8n_to_uvchr((U8*)PL_reginput,
+                                          UTF8_MAXBYTES, 0, uniflags)
+                               : (UV) UCHARAT(PL_reginput);
+               /* If it could work, try it. */
+               if (ST.c1 == CHRTEST_VOID || c == (UV)ST.c1 || c == (UV)ST.c2) {
+                   CURLY_SETPAREN(ST.paren, ST.count);
+                   PUSH_STATE_GOTO(CURLY_B_max, ST.B);
+                   /* NOTREACHED */
+               }
+           }
+           /* FALL THROUGH */
+       case CURLY_B_max_fail:
+           /* failed to find B in a greedy match */
+           if (ST.paren && ST.count)
+               PL_regoffs[ST.paren].end = -1;
+
+           REGCP_UNWIND(ST.cp);
+           /*  back up. */
+           if (--ST.count < ST.min)
+               sayNO;
+           PL_reginput = locinput = HOPc(locinput, -1);
+           goto curly_try_B_max;
+
+#undef ST
+
+       case END:
+           fake_end:
+           if (cur_eval) {
+               /* we've just finished A in /(??{A})B/; now continue with B */
+               I32 tmpix;
+               st->u.eval.toggle_reg_flags
+                           = cur_eval->u.eval.toggle_reg_flags;
+               PL_reg_flags ^= st->u.eval.toggle_reg_flags; 
+
+               st->u.eval.prev_rex = rex_sv;           /* inner */
+               SETREX(rex_sv,cur_eval->u.eval.prev_rex);
+               rex = (struct regexp *)SvANY(rex_sv);
+               rexi = RXi_GET(rex);
+               cur_curlyx = cur_eval->u.eval.prev_curlyx;
+               ReREFCNT_inc(rex_sv);
+               st->u.eval.cp = regcppush(0);   /* Save *all* the positions. */
+
+               /* rex was changed so update the pointer in PL_reglastparen and PL_reglastcloseparen */
+               PL_reglastparen = &rex->lastparen;
+               PL_reglastcloseparen = &rex->lastcloseparen;
+
+               REGCP_SET(st->u.eval.lastcp);
+               PL_reginput = locinput;
+
+               /* Restore parens of the outer rex without popping the
+                * savestack */
+               tmpix = PL_savestack_ix;
+               PL_savestack_ix = cur_eval->u.eval.lastcp;
+               regcppop(rex);
+               PL_savestack_ix = tmpix;
+
+               st->u.eval.prev_eval = cur_eval;
+               cur_eval = cur_eval->u.eval.prev_eval;
+               DEBUG_EXECUTE_r(
+                   PerlIO_printf(Perl_debug_log, "%*s  EVAL trying tail ... %"UVxf"\n",
+                                     REPORT_CODE_OFF+depth*2, "",PTR2UV(cur_eval)););
+                if ( nochange_depth )
+                   nochange_depth--;
+
+                PUSH_YES_STATE_GOTO(EVAL_AB,
+                       st->u.eval.prev_eval->u.eval.B); /* match B */
+           }
+
+           if (locinput < reginfo->till) {
+               DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+                                     "%sMatch possible, but length=%ld is smaller than requested=%ld, failing!%s\n",
+                                     PL_colors[4],
+                                     (long)(locinput - PL_reg_starttry),
+                                     (long)(reginfo->till - PL_reg_starttry),
+                                     PL_colors[5]));
+                                                     
+               sayNO_SILENT;           /* Cannot match: too short. */
+           }
+           PL_reginput = locinput;     /* put where regtry can find it */
+           sayYES;                     /* Success! */
+
+       case SUCCEED: /* successful SUSPEND/UNLESSM/IFMATCH/CURLYM */
+           DEBUG_EXECUTE_r(
+           PerlIO_printf(Perl_debug_log,
+               "%*s  %ssubpattern success...%s\n",
+               REPORT_CODE_OFF+depth*2, "", PL_colors[4], PL_colors[5]));
+           PL_reginput = locinput;     /* put where regtry can find it */
+           sayYES;                     /* Success! */
+
+#undef  ST
+#define ST st->u.ifmatch
+
+       case SUSPEND:   /* (?>A) */
+           ST.wanted = 1;
+           PL_reginput = locinput;
+           goto do_ifmatch;    
+
+       case UNLESSM:   /* -ve lookaround: (?!A), or with flags, (?<!A) */
+           ST.wanted = 0;
+           goto ifmatch_trivial_fail_test;
+
+       case IFMATCH:   /* +ve lookaround: (?=A), or with flags, (?<=A) */
+           ST.wanted = 1;
+         ifmatch_trivial_fail_test:
+           if (scan->flags) {
+               char * const s = HOPBACKc(locinput, scan->flags);
+               if (!s) {
+                   /* trivial fail */
+                   if (logical) {
+                       logical = 0;
+                       sw = 1 - (bool)ST.wanted;
+                   }
+                   else if (ST.wanted)
+                       sayNO;
+                   next = scan + ARG(scan);
+                   if (next == scan)
+                       next = NULL;
+                   break;
+               }
+               PL_reginput = s;
+           }
+           else
+               PL_reginput = locinput;
+
+         do_ifmatch:
+           ST.me = scan;
+           ST.logical = logical;
+           logical = 0; /* XXX: reset state of logical once it has been saved into ST */
+           
+           /* execute body of (?...A) */
+           PUSH_YES_STATE_GOTO(IFMATCH_A, NEXTOPER(NEXTOPER(scan)));
+           /* NOTREACHED */
+
+       case IFMATCH_A_fail: /* body of (?...A) failed */
+           ST.wanted = !ST.wanted;
+           /* FALL THROUGH */
+
+       case IFMATCH_A: /* body of (?...A) succeeded */
+           if (ST.logical) {
+               sw = (bool)ST.wanted;
+           }
+           else if (!ST.wanted)
+               sayNO;
+
+           if (OP(ST.me) == SUSPEND)
+               locinput = PL_reginput;
+           else {
+               locinput = PL_reginput = st->locinput;
+               nextchr = UCHARAT(locinput);
+           }
+           scan = ST.me + ARG(ST.me);
+           if (scan == ST.me)
+               scan = NULL;
+           continue; /* execute B */
+
+#undef ST
+
+       case LONGJMP:
+           next = scan + ARG(scan);
+           if (next == scan)
+               next = NULL;
+           break;
+       case COMMIT:
+           reginfo->cutpoint = PL_regeol;
+           /* FALLTHROUGH */
+       case PRUNE:
+           PL_reginput = locinput;
+           if (!scan->flags)
+               sv_yes_mark = sv_commit = MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
+           PUSH_STATE_GOTO(COMMIT_next,next);
+           /* NOTREACHED */
+       case COMMIT_next_fail:
+           no_final = 1;    
+           /* FALLTHROUGH */       
+       case OPFAIL:
+           sayNO;
+           /* NOTREACHED */
+
+#define ST st->u.mark
+        case MARKPOINT:
+            ST.prev_mark = mark_state;
+            ST.mark_name = sv_commit = sv_yes_mark 
+                = MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
+            mark_state = st;
+            ST.mark_loc = PL_reginput = locinput;
+            PUSH_YES_STATE_GOTO(MARKPOINT_next,next);
+            /* NOTREACHED */
+        case MARKPOINT_next:
+            mark_state = ST.prev_mark;
+            sayYES;
+            /* NOTREACHED */
+        case MARKPOINT_next_fail:
+            if (popmark && sv_eq(ST.mark_name,popmark)) 
+            {
+                if (ST.mark_loc > startpoint)
+                   reginfo->cutpoint = HOPBACKc(ST.mark_loc, 1);
+                popmark = NULL; /* we found our mark */
+                sv_commit = ST.mark_name;
+
+                DEBUG_EXECUTE_r({
+                        PerlIO_printf(Perl_debug_log,
+                           "%*s  %ssetting cutpoint to mark:%"SVf"...%s\n",
+                           REPORT_CODE_OFF+depth*2, "", 
+                           PL_colors[4], SVfARG(sv_commit), PL_colors[5]);
+               });
+            }
+            mark_state = ST.prev_mark;
+            sv_yes_mark = mark_state ? 
+                mark_state->u.mark.mark_name : NULL;
+            sayNO;
+            /* NOTREACHED */
+        case SKIP:
+            PL_reginput = locinput;
+            if (scan->flags) {
+                /* (*SKIP) : if we fail we cut here*/
+                ST.mark_name = NULL;
+                ST.mark_loc = locinput;
+                PUSH_STATE_GOTO(SKIP_next,next);    
+            } else {
+                /* (*SKIP:NAME) : if there is a (*MARK:NAME) fail where it was, 
+                   otherwise do nothing.  Meaning we need to scan 
+                 */
+                regmatch_state *cur = mark_state;
+                SV *find = MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
+                
+                while (cur) {
+                    if ( sv_eq( cur->u.mark.mark_name, 
+                                find ) ) 
+                    {
+                        ST.mark_name = find;
+                        PUSH_STATE_GOTO( SKIP_next, next );
+                    }
+                    cur = cur->u.mark.prev_mark;
+                }
+            }    
+            /* Didn't find our (*MARK:NAME) so ignore this (*SKIP:NAME) */
+            break;    
+       case SKIP_next_fail:
+           if (ST.mark_name) {
+               /* (*CUT:NAME) - Set up to search for the name as we 
+                  collapse the stack*/
+               popmark = ST.mark_name;    
+           } else {
+               /* (*CUT) - No name, we cut here.*/
+               if (ST.mark_loc > startpoint)
+                   reginfo->cutpoint = HOPBACKc(ST.mark_loc, 1);
+               /* but we set sv_commit to latest mark_name if there
+                  is one so they can test to see how things lead to this
+                  cut */    
+                if (mark_state) 
+                    sv_commit=mark_state->u.mark.mark_name;                
+            } 
+            no_final = 1; 
+            sayNO;
+            /* NOTREACHED */
+#undef ST
+        case FOLDCHAR:
+            n = ARG(scan);
+            if ( n == (U32)what_len_TRICKYFOLD(locinput,do_utf8,ln) ) {
+                locinput += ln;
+            } else if ( 0xDF == n && !do_utf8 && !UTF ) {
+                sayNO;
+            } else  {
+                U8 folded[UTF8_MAXBYTES_CASE+1];
+                STRLEN foldlen;
+                const char * const l = locinput;
+                char *e = PL_regeol;
+                to_uni_fold(n, folded, &foldlen);
+
+               if (ibcmp_utf8((const char*) folded, 0,  foldlen, 1,
+                              l, &e, 0,  do_utf8)) {
+                        sayNO;
+                }
+                locinput = e;
+            } 
+            nextchr = UCHARAT(locinput);  
+            break;
+        case LNBREAK:
+            if ((n=is_LNBREAK(locinput,do_utf8))) {
+                locinput += n;
+                nextchr = UCHARAT(locinput);
+            } else
+                sayNO;
+            break;
+
+#define CASE_CLASS(nAmE)                              \
+        case nAmE:                                    \
+            if ((n=is_##nAmE(locinput,do_utf8))) {    \
+                locinput += n;                        \
+                nextchr = UCHARAT(locinput);          \
+            } else                                    \
+                sayNO;                                \
+            break;                                    \
+        case N##nAmE:                                 \
+            if ((n=is_##nAmE(locinput,do_utf8))) {    \
+                sayNO;                                \
+            } else {                                  \
+                locinput += UTF8SKIP(locinput);       \
+                nextchr = UCHARAT(locinput);          \
+            }                                         \
+            break
+
+        CASE_CLASS(VERTWS);
+        CASE_CLASS(HORIZWS);
+#undef CASE_CLASS
+
+       default:
+           PerlIO_printf(Perl_error_log, "%"UVxf" %d\n",
+                         PTR2UV(scan), OP(scan));
+           Perl_croak(aTHX_ "regexp memory corruption");
+           
+       } /* end switch */ 
+
+        /* switch break jumps here */
+       scan = next; /* prepare to execute the next op and ... */
+       continue;    /* ... jump back to the top, reusing st */
+       /* NOTREACHED */
+
+      push_yes_state:
+       /* push a state that backtracks on success */
+       st->u.yes.prev_yes_state = yes_state;
+       yes_state = st;
+       /* FALL THROUGH */
+      push_state:
+       /* push a new regex state, then continue at scan  */
+       {
+           regmatch_state *newst;
+
+           DEBUG_STACK_r({
+               regmatch_state *cur = st;
+               regmatch_state *curyes = yes_state;
+               int curd = depth;
+               regmatch_slab *slab = PL_regmatch_slab;
+                for (;curd > -1;cur--,curd--) {
+                    if (cur < SLAB_FIRST(slab)) {
+                       slab = slab->prev;
+                       cur = SLAB_LAST(slab);
+                    }
+                    PerlIO_printf(Perl_error_log, "%*s#%-3d %-10s %s\n",
+                        REPORT_CODE_OFF + 2 + depth * 2,"",
+                        curd, PL_reg_name[cur->resume_state],
+                        (curyes == cur) ? "yes" : ""
+                    );
+                    if (curyes == cur)
+                       curyes = cur->u.yes.prev_yes_state;
+                }
+            } else 
+                DEBUG_STATE_pp("push")
+            );
+           depth++;
+           st->locinput = locinput;
+           newst = st+1; 
+           if (newst >  SLAB_LAST(PL_regmatch_slab))
+               newst = S_push_slab(aTHX);
+           PL_regmatch_state = newst;
+
+           locinput = PL_reginput;
+           nextchr = UCHARAT(locinput);
+           st = newst;
+           continue;
+           /* NOTREACHED */
+       }
+    }
+
+    /*
+    * We get here only if there's trouble -- normally "case END" is
+    * the terminating point.
+    */
+    Perl_croak(aTHX_ "corrupted regexp pointers");
+    /*NOTREACHED*/
+    sayNO;
+
+yes:
+    if (yes_state) {
+       /* we have successfully completed a subexpression, but we must now
+        * pop to the state marked by yes_state and continue from there */
+       assert(st != yes_state);
+#ifdef DEBUGGING
+       while (st != yes_state) {
+           st--;
+           if (st < SLAB_FIRST(PL_regmatch_slab)) {
+               PL_regmatch_slab = PL_regmatch_slab->prev;
+               st = SLAB_LAST(PL_regmatch_slab);
+           }
+           DEBUG_STATE_r({
+               if (no_final) {
+                   DEBUG_STATE_pp("pop (no final)");        
+               } else {
+                   DEBUG_STATE_pp("pop (yes)");
+               }
+           });
+           depth--;
+       }
+#else
+       while (yes_state < SLAB_FIRST(PL_regmatch_slab)
+           || yes_state > SLAB_LAST(PL_regmatch_slab))
+       {
+           /* not in this slab, pop slab */
+           depth -= (st - SLAB_FIRST(PL_regmatch_slab) + 1);
+           PL_regmatch_slab = PL_regmatch_slab->prev;
+           st = SLAB_LAST(PL_regmatch_slab);
+       }
+       depth -= (st - yes_state);
+#endif
+       st = yes_state;
+       yes_state = st->u.yes.prev_yes_state;
+       PL_regmatch_state = st;
+        
+        if (no_final) {
+            locinput= st->locinput;
+            nextchr = UCHARAT(locinput);
+        }
+       state_num = st->resume_state + no_final;
+       goto reenter_switch;
+    }
+
+    DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%sMatch successful!%s\n",
+                         PL_colors[4], PL_colors[5]));
+
+    if (PL_reg_eval_set) {
+       /* each successfully executed (?{...}) block does the equivalent of
+        *   local $^R = do {...}
+        * When popping the save stack, all these locals would be undone;
+        * bypass this by setting the outermost saved $^R to the latest
+        * value */
+       if (oreplsv != GvSV(PL_replgv))
+           sv_setsv(oreplsv, GvSV(PL_replgv));
+    }
+    result = 1;
+    goto final_exit;
+
+no:
+    DEBUG_EXECUTE_r(
+       PerlIO_printf(Perl_debug_log,
+            "%*s  %sfailed...%s\n",
+            REPORT_CODE_OFF+depth*2, "", 
+            PL_colors[4], PL_colors[5])
+       );
+
+no_silent:
+    if (no_final) {
+        if (yes_state) {
+            goto yes;
+        } else {
+            goto final_exit;
+        }
+    }    
+    if (depth) {
+       /* there's a previous state to backtrack to */
+       st--;
+       if (st < SLAB_FIRST(PL_regmatch_slab)) {
+           PL_regmatch_slab = PL_regmatch_slab->prev;
+           st = SLAB_LAST(PL_regmatch_slab);
+       }
+       PL_regmatch_state = st;
+       locinput= st->locinput;
+       nextchr = UCHARAT(locinput);
+
+       DEBUG_STATE_pp("pop");
+       depth--;
+       if (yes_state == st)
+           yes_state = st->u.yes.prev_yes_state;
+
+       state_num = st->resume_state + 1; /* failure = success + 1 */
+       goto reenter_switch;
+    }
+    result = 0;
+
+  final_exit:
+    if (rex->intflags & PREGf_VERBARG_SEEN) {
+        SV *sv_err = get_sv("REGERROR", 1);
+        SV *sv_mrk = get_sv("REGMARK", 1);
+        if (result) {
+            sv_commit = &PL_sv_no;
+            if (!sv_yes_mark) 
+                sv_yes_mark = &PL_sv_yes;
+        } else {
+            if (!sv_commit) 
+                sv_commit = &PL_sv_yes;
+            sv_yes_mark = &PL_sv_no;
+        }
+        sv_setsv(sv_err, sv_commit);
+        sv_setsv(sv_mrk, sv_yes_mark);
+    }
+
+    /* clean up; in particular, free all slabs above current one */
+    LEAVE_SCOPE(oldsave);
+
+    return result;
+}
+
+/*
+ - regrepeat - repeatedly match something simple, report how many
+ */
+/*
+ * [This routine now assumes that it will only match on things of length 1.
+ * That was true before, but now we assume scan - reginput is the count,
+ * rather than incrementing count on every character.  [Er, except utf8.]]
+ */
+STATIC I32
+S_regrepeat(pTHX_ const regexp *prog, const regnode *p, I32 max, int depth)
+{
+    dVAR;
+    register char *scan;
+    register I32 c;
+    register char *loceol = PL_regeol;
+    register I32 hardcount = 0;
+    register bool do_utf8 = PL_reg_match_utf8;
+#ifndef DEBUGGING
+    PERL_UNUSED_ARG(depth);
+#endif
+
+    PERL_ARGS_ASSERT_REGREPEAT;
+
+    scan = PL_reginput;
+    if (max == REG_INFTY)
+       max = I32_MAX;
+    else if (max < loceol - scan)
+       loceol = scan + max;
+    switch (OP(p)) {
+    case REG_ANY:
+       if (do_utf8) {
+           loceol = PL_regeol;
+           while (scan < loceol && hardcount < max && *scan != '\n') {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && *scan != '\n')
+               scan++;
+       }
+       break;
+    case SANY:
+        if (do_utf8) {
+           loceol = PL_regeol;
+           while (scan < loceol && hardcount < max) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       }
+       else
+           scan = loceol;
+       break;
+    case CANY:
+       scan = loceol;
+       break;
+    case EXACT:                /* length of string is 1 */
+       c = (U8)*STRING(p);
+       while (scan < loceol && UCHARAT(scan) == c)
+           scan++;
+       break;
+    case EXACTF:       /* length of string is 1 */
+       c = (U8)*STRING(p);
+       while (scan < loceol &&
+              (UCHARAT(scan) == c || UCHARAT(scan) == PL_fold[c]))
+           scan++;
+       break;
+    case EXACTFL:      /* length of string is 1 */
+       PL_reg_flags |= RF_tainted;
+       c = (U8)*STRING(p);
+       while (scan < loceol &&
+              (UCHARAT(scan) == c || UCHARAT(scan) == PL_fold_locale[c]))
+           scan++;
+       break;
+    case ANYOF:
+       if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol &&
+                  reginclass(prog, p, (U8*)scan, 0, do_utf8)) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && REGINCLASS(prog, p, (U8*)scan))
+               scan++;
+       }
+       break;
+    case ALNUM:
+       if (do_utf8) {
+           loceol = PL_regeol;
+           LOAD_UTF8_CHARCLASS_ALNUM();
+           while (hardcount < max && scan < loceol &&
+                  swash_fetch(PL_utf8_alnum, (U8*)scan, do_utf8)) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && isALNUM(*scan))
+               scan++;
+       }
+       break;
+    case ALNUML:
+       PL_reg_flags |= RF_tainted;
+       if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol &&
+                  isALNUM_LC_utf8((U8*)scan)) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && isALNUM_LC(*scan))
+               scan++;
+       }
+       break;
+    case NALNUM:
+       if (do_utf8) {
+           loceol = PL_regeol;
+           LOAD_UTF8_CHARCLASS_ALNUM();
+           while (hardcount < max && scan < loceol &&
+                  !swash_fetch(PL_utf8_alnum, (U8*)scan, do_utf8)) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && !isALNUM(*scan))
+               scan++;
+       }
+       break;
+    case NALNUML:
+       PL_reg_flags |= RF_tainted;
+       if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol &&
+                  !isALNUM_LC_utf8((U8*)scan)) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && !isALNUM_LC(*scan))
+               scan++;
+       }
+       break;
+    case SPACE:
+       if (do_utf8) {
+           loceol = PL_regeol;
+           LOAD_UTF8_CHARCLASS_SPACE();
+           while (hardcount < max && scan < loceol &&
+                  (*scan == ' ' ||
+                   swash_fetch(PL_utf8_space,(U8*)scan, do_utf8))) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && isSPACE(*scan))
+               scan++;
+       }
+       break;
+    case SPACEL:
+       PL_reg_flags |= RF_tainted;
+       if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol &&
+                  (*scan == ' ' || isSPACE_LC_utf8((U8*)scan))) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && isSPACE_LC(*scan))
+               scan++;
+       }
+       break;
+    case NSPACE:
+       if (do_utf8) {
+           loceol = PL_regeol;
+           LOAD_UTF8_CHARCLASS_SPACE();
+           while (hardcount < max && scan < loceol &&
+                  !(*scan == ' ' ||
+                    swash_fetch(PL_utf8_space,(U8*)scan, do_utf8))) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && !isSPACE(*scan))
+               scan++;
+       }
+       break;
+    case NSPACEL:
+       PL_reg_flags |= RF_tainted;
+       if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol &&
+                  !(*scan == ' ' || isSPACE_LC_utf8((U8*)scan))) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && !isSPACE_LC(*scan))
+               scan++;
+       }
+       break;
+    case DIGIT:
+       if (do_utf8) {
+           loceol = PL_regeol;
+           LOAD_UTF8_CHARCLASS_DIGIT();
+           while (hardcount < max && scan < loceol &&
+                  swash_fetch(PL_utf8_digit, (U8*)scan, do_utf8)) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && isDIGIT(*scan))
+               scan++;
+       }
+       break;
+    case NDIGIT:
+       if (do_utf8) {
+           loceol = PL_regeol;
+           LOAD_UTF8_CHARCLASS_DIGIT();
+           while (hardcount < max && scan < loceol &&
+                  !swash_fetch(PL_utf8_digit, (U8*)scan, do_utf8)) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && !isDIGIT(*scan))
+               scan++;
+       }
+    case LNBREAK:
+        if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol && (c=is_LNBREAK_utf8(scan))) {
+               scan += c;
+               hardcount++;
+           }
+       } else {
+           /*
+             LNBREAK can match two latin chars, which is ok,
+             because we have a null terminated string, but we
+             have to use hardcount in this situation
+           */
+           while (scan < loceol && (c=is_LNBREAK_latin1(scan)))  {
+               scan+=c;
+               hardcount++;
+           }
+       }       
+       break;
+    case HORIZWS:
+        if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol && (c=is_HORIZWS_utf8(scan))) {
+               scan += c;
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && is_HORIZWS_latin1(scan)) 
+               scan++;         
+       }       
+       break;
+    case NHORIZWS:
+        if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol && !is_HORIZWS_utf8(scan)) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && !is_HORIZWS_latin1(scan))
+               scan++;
+
+       }       
+       break;
+    case VERTWS:
+        if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol && (c=is_VERTWS_utf8(scan))) {
+               scan += c;
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && is_VERTWS_latin1(scan)) 
+               scan++;
+
+       }       
+       break;
+    case NVERTWS:
+        if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol && !is_VERTWS_utf8(scan)) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && !is_VERTWS_latin1(scan)) 
+               scan++;
+          
+       }       
+       break;
+
+    default:           /* Called on something of 0 width. */
+       break;          /* So match right here or not at all. */
+    }
+
+    if (hardcount)
+       c = hardcount;
+    else
+       c = scan - PL_reginput;
+    PL_reginput = scan;
+
+    DEBUG_r({
+       GET_RE_DEBUG_FLAGS_DECL;
+       DEBUG_EXECUTE_r({
+           SV * const prop = sv_newmortal();
+           regprop(prog, prop, p);
+           PerlIO_printf(Perl_debug_log,
+                       "%*s  %s can match %"IVdf" times out of %"IVdf"...\n",
+                       REPORT_CODE_OFF + depth*2, "", SvPVX_const(prop),(IV)c,(IV)max);
+       });
+    });
+
+    return(c);
+}
+
+
+#if !defined(PERL_IN_XSUB_RE) || defined(PLUGGABLE_RE_EXTENSION)
+/*
+- regclass_swash - prepare the utf8 swash
+*/
+
+SV *
+Perl_regclass_swash(pTHX_ const regexp *prog, register const regnode* node, bool doinit, SV** listsvp, SV **altsvp)
+{
+    dVAR;
+    SV *sw  = NULL;
+    SV *si  = NULL;
+    SV *alt = NULL;
+    RXi_GET_DECL(prog,progi);
+    const struct reg_data * const data = prog ? progi->data : NULL;
+
+    PERL_ARGS_ASSERT_REGCLASS_SWASH;
+
+    if (data && data->count) {
+       const U32 n = ARG(node);
+
+       if (data->what[n] == 's') {
+           SV * const rv = MUTABLE_SV(data->data[n]);
+           AV * const av = MUTABLE_AV(SvRV(rv));
+           SV **const ary = AvARRAY(av);
+           SV **a, **b;
+       
+           /* See the end of regcomp.c:S_regclass() for
+            * documentation of these array elements. */
+
+           si = *ary;
+           a  = SvROK(ary[1]) ? &ary[1] : NULL;
+           b  = SvTYPE(ary[2]) == SVt_PVAV ? &ary[2] : NULL;
+
+           if (a)
+               sw = *a;
+           else if (si && doinit) {
+               sw = swash_init("utf8", "", si, 1, 0);
+               (void)av_store(av, 1, sw);
+           }
+           if (b)
+               alt = *b;
+       }
+    }
+       
+    if (listsvp)
+       *listsvp = si;
+    if (altsvp)
+       *altsvp  = alt;
+
+    return sw;
+}
+#endif
+
+/*
+ - reginclass - determine if a character falls into a character class
+  The n is the ANYOF regnode, the p is the target string, lenp
+  is pointer to the maximum length of how far to go in the p
+  (if the lenp is zero, UTF8SKIP(p) is used),
+  do_utf8 tells whether the target string is in UTF-8.
+
+ */
+
+STATIC bool
+S_reginclass(pTHX_ const regexp *prog, register const regnode *n, register const U8* p, STRLEN* lenp, register bool do_utf8)
+{
+    dVAR;
+    const char flags = ANYOF_FLAGS(n);
+    bool match = FALSE;
+    UV c = *p;
+    STRLEN len = 0;
+    STRLEN plen;
+
+    PERL_ARGS_ASSERT_REGINCLASS;
+
+    if (do_utf8 && !UTF8_IS_INVARIANT(c)) {
+       c = utf8n_to_uvchr(p, UTF8_MAXBYTES, &len,
+               (UTF8_ALLOW_DEFAULT & UTF8_ALLOW_ANYUV)
+               | UTF8_ALLOW_FFFF | UTF8_CHECK_ONLY);
+               /* see [perl #37836] for UTF8_ALLOW_ANYUV; [perl #38293] for
+                * UTF8_ALLOW_FFFF */
+       if (len == (STRLEN)-1) 
+           Perl_croak(aTHX_ "Malformed UTF-8 character (fatal)");
+    }
+
+    plen = lenp ? *lenp : UNISKIP(NATIVE_TO_UNI(c));
+    if (do_utf8 || (flags & ANYOF_UNICODE)) {
+        if (lenp)
+           *lenp = 0;
+       if (do_utf8 && !ANYOF_RUNTIME(n)) {
+           if (len != (STRLEN)-1 && c < 256 && ANYOF_BITMAP_TEST(n, c))
+               match = TRUE;
+       }
+       if (!match && do_utf8 && (flags & ANYOF_UNICODE_ALL) && c >= 256)
+           match = TRUE;
+       if (!match) {
+           AV *av;
+           SV * const sw = regclass_swash(prog, n, TRUE, 0, (SV**)&av);
+       
+           if (sw) {
+               U8 * utf8_p;
+               if (do_utf8) {
+                   utf8_p = (U8 *) p;
+               } else {
+                   STRLEN len = 1;
+                   utf8_p = bytes_to_utf8(p, &len);
+               }
+               if (swash_fetch(sw, utf8_p, 1))
+                   match = TRUE;
+               else if (flags & ANYOF_FOLD) {
+                   if (!match && lenp && av) {
+                       I32 i;
+                       for (i = 0; i <= av_len(av); i++) {
+                           SV* const sv = *av_fetch(av, i, FALSE);
+                           STRLEN len;
+                           const char * const s = SvPV_const(sv, len);
+                           if (len <= plen && memEQ(s, (char*)utf8_p, len)) {
+                               *lenp = len;
+                               match = TRUE;
+                               break;
+                           }
+                       }
+                   }
+                   if (!match) {
+                       U8 tmpbuf[UTF8_MAXBYTES_CASE+1];
+
+                       STRLEN tmplen;
+                       to_utf8_fold(utf8_p, tmpbuf, &tmplen);
+                       if (swash_fetch(sw, tmpbuf, 1))
+                           match = TRUE;
+                   }
+               }
+
+               /* If we allocated a string above, free it */
+               if (! do_utf8) Safefree(utf8_p);
+           }
+       }
+       if (match && lenp && *lenp == 0)
+           *lenp = UNISKIP(NATIVE_TO_UNI(c));
+    }
+    if (!match && c < 256) {
+       if (ANYOF_BITMAP_TEST(n, c))
+           match = TRUE;
+       else if (flags & ANYOF_FOLD) {
+           U8 f;
+
+           if (flags & ANYOF_LOCALE) {
+               PL_reg_flags |= RF_tainted;
+               f = PL_fold_locale[c];
+           }
+           else
+               f = PL_fold[c];
+           if (f != c && ANYOF_BITMAP_TEST(n, f))
+               match = TRUE;
+       }
+       
+       if (!match && (flags & ANYOF_CLASS)) {
+           PL_reg_flags |= RF_tainted;
+           if (
+               (ANYOF_CLASS_TEST(n, ANYOF_ALNUM)   &&  isALNUM_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NALNUM)  && !isALNUM_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_SPACE)   &&  isSPACE_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NSPACE)  && !isSPACE_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_DIGIT)   &&  isDIGIT_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NDIGIT)  && !isDIGIT_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_ALNUMC)  &&  isALNUMC_LC(c)) ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NALNUMC) && !isALNUMC_LC(c)) ||
+               (ANYOF_CLASS_TEST(n, ANYOF_ALPHA)   &&  isALPHA_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NALPHA)  && !isALPHA_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_ASCII)   &&  isASCII(c))     ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NASCII)  && !isASCII(c))     ||
+               (ANYOF_CLASS_TEST(n, ANYOF_CNTRL)   &&  isCNTRL_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NCNTRL)  && !isCNTRL_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_GRAPH)   &&  isGRAPH_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NGRAPH)  && !isGRAPH_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_LOWER)   &&  isLOWER_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NLOWER)  && !isLOWER_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_PRINT)   &&  isPRINT_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NPRINT)  && !isPRINT_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_PUNCT)   &&  isPUNCT_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NPUNCT)  && !isPUNCT_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_UPPER)   &&  isUPPER_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NUPPER)  && !isUPPER_LC(c))  ||
+               (ANYOF_CLASS_TEST(n, ANYOF_XDIGIT)  &&  isXDIGIT(c))    ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NXDIGIT) && !isXDIGIT(c))    ||
+               (ANYOF_CLASS_TEST(n, ANYOF_PSXSPC)  &&  isPSXSPC(c))    ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NPSXSPC) && !isPSXSPC(c))    ||
+               (ANYOF_CLASS_TEST(n, ANYOF_BLANK)   &&  isBLANK(c))     ||
+               (ANYOF_CLASS_TEST(n, ANYOF_NBLANK)  && !isBLANK(c))
+               ) /* How's that for a conditional? */
+           {
+               match = TRUE;
+           }
+       }
+    }
+
+    return (flags & ANYOF_INVERT) ? !match : match;
+}
+
+STATIC U8 *
+S_reghop3(U8 *s, I32 off, const U8* lim)
+{
+    dVAR;
+
+    PERL_ARGS_ASSERT_REGHOP3;
+
+    if (off >= 0) {
+       while (off-- && s < lim) {
+           /* XXX could check well-formedness here */
+           s += UTF8SKIP(s);
+       }
+    }
+    else {
+        while (off++ && s > lim) {
+            s--;
+            if (UTF8_IS_CONTINUED(*s)) {
+                while (s > lim && UTF8_IS_CONTINUATION(*s))
+                    s--;
+           }
+            /* XXX could check well-formedness here */
+       }
+    }
+    return s;
+}
+
+#ifdef XXX_dmq
+/* there are a bunch of places where we use two reghop3's that should
+   be replaced with this routine. but since thats not done yet 
+   we ifdef it out - dmq
+*/
+STATIC U8 *
+S_reghop4(U8 *s, I32 off, const U8* llim, const U8* rlim)
+{
+    dVAR;
+
+    PERL_ARGS_ASSERT_REGHOP4;
+
+    if (off >= 0) {
+        while (off-- && s < rlim) {
+            /* XXX could check well-formedness here */
+            s += UTF8SKIP(s);
+        }
+    }
+    else {
+        while (off++ && s > llim) {
+            s--;
+            if (UTF8_IS_CONTINUED(*s)) {
+                while (s > llim && UTF8_IS_CONTINUATION(*s))
+                    s--;
+            }
+            /* XXX could check well-formedness here */
+        }
+    }
+    return s;
+}
+#endif
+
+STATIC U8 *
+S_reghopmaybe3(U8* s, I32 off, const U8* lim)
+{
+    dVAR;
+
+    PERL_ARGS_ASSERT_REGHOPMAYBE3;
+
+    if (off >= 0) {
+       while (off-- && s < lim) {
+           /* XXX could check well-formedness here */
+           s += UTF8SKIP(s);
+       }
+       if (off >= 0)
+           return NULL;
+    }
+    else {
+        while (off++ && s > lim) {
+            s--;
+            if (UTF8_IS_CONTINUED(*s)) {
+                while (s > lim && UTF8_IS_CONTINUATION(*s))
+                    s--;
+           }
+            /* XXX could check well-formedness here */
+       }
+       if (off <= 0)
+           return NULL;
+    }
+    return s;
+}
+
+static void
+restore_pos(pTHX_ void *arg)
+{
+    dVAR;
+    regexp * const rex = (regexp *)arg;
+    if (PL_reg_eval_set) {
+       if (PL_reg_oldsaved) {
+           rex->subbeg = PL_reg_oldsaved;
+           rex->sublen = PL_reg_oldsavedlen;
+#ifdef PERL_OLD_COPY_ON_WRITE
+           rex->saved_copy = PL_nrs;
+#endif
+           RXp_MATCH_COPIED_on(rex);
+       }
+       PL_reg_magic->mg_len = PL_reg_oldpos;
+       PL_reg_eval_set = 0;
+       PL_curpm = PL_reg_oldcurpm;
+    }  
+}
+
+STATIC void
+S_to_utf8_substr(pTHX_ register regexp *prog)
+{
+    int i = 1;
+
+    PERL_ARGS_ASSERT_TO_UTF8_SUBSTR;
+
+    do {
+       if (prog->substrs->data[i].substr
+           && !prog->substrs->data[i].utf8_substr) {
+           SV* const sv = newSVsv(prog->substrs->data[i].substr);
+           prog->substrs->data[i].utf8_substr = sv;
+           sv_utf8_upgrade(sv);
+           if (SvVALID(prog->substrs->data[i].substr)) {
+               const U8 flags = BmFLAGS(prog->substrs->data[i].substr);
+               if (flags & FBMcf_TAIL) {
+                   /* Trim the trailing \n that fbm_compile added last
+                      time.  */
+                   SvCUR_set(sv, SvCUR(sv) - 1);
+                   /* Whilst this makes the SV technically "invalid" (as its
+                      buffer is no longer followed by "\0") when fbm_compile()
+                      adds the "\n" back, a "\0" is restored.  */
+               }
+               fbm_compile(sv, flags);
+           }
+           if (prog->substrs->data[i].substr == prog->check_substr)
+               prog->check_utf8 = sv;
+       }
+    } while (i--);
+}
+
+STATIC void
+S_to_byte_substr(pTHX_ register regexp *prog)
+{
+    dVAR;
+    int i = 1;
+
+    PERL_ARGS_ASSERT_TO_BYTE_SUBSTR;
+
+    do {
+       if (prog->substrs->data[i].utf8_substr
+           && !prog->substrs->data[i].substr) {
+           SV* sv = newSVsv(prog->substrs->data[i].utf8_substr);
+           if (sv_utf8_downgrade(sv, TRUE)) {
+               if (SvVALID(prog->substrs->data[i].utf8_substr)) {
+                   const U8 flags
+                       = BmFLAGS(prog->substrs->data[i].utf8_substr);
+                   if (flags & FBMcf_TAIL) {
+                       /* Trim the trailing \n that fbm_compile added last
+                          time.  */
+                       SvCUR_set(sv, SvCUR(sv) - 1);
+                   }
+                   fbm_compile(sv, flags);
+               }           
+           } else {
+               SvREFCNT_dec(sv);
+               sv = &PL_sv_undef;
+           }
+           prog->substrs->data[i].substr = sv;
+           if (prog->substrs->data[i].utf8_substr == prog->check_utf8)
+               prog->check_substr = sv;
+       }
+    } while (i--);
+}
+
+/*
+ * Local variables:
+ * c-indentation-style: bsd
+ * c-basic-offset: 4
+ * indent-tabs-mode: t
+ * End:
+ *
+ * ex: set ts=8 sts=4 sw=4 noet:
+ */