[perl5.git] / pp_ctl.c

/*    pp_ctl.c
 *
 *    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.
 *
 */

/*
 *      Now far ahead the Road has gone,
 *          And I must follow, if I can,
 *      Pursuing it with eager feet,
 *          Until it joins some larger way
 *      Where many paths and errands meet.
 *          And whither then?  I cannot say.
 *
 *     [Bilbo on p.35 of _The Lord of the Rings_, I/i: "A Long-Expected Party"]
 */

/* This file contains control-oriented pp ("push/pop") functions that
 * execute the opcodes that make up a perl program. A typical pp function
 * expects to find its arguments on the stack, and usually pushes its
 * results onto the stack, hence the 'pp' terminology. Each OP structure
 * contains a pointer to the relevant pp_foo() function.
 *
 * Control-oriented means things like pp_enteriter() and pp_next(), which
 * alter the flow of control of the program.
 */


#include "EXTERN.h"
#define PERL_IN_PP_CTL_C
#include "perl.h"

#ifndef WORD_ALIGN
#define WORD_ALIGN sizeof(U32)
#endif

#define DOCATCH(o) ((CATCH_GET == TRUE) ? docatch(o) : (o))

#define dopoptosub(plop)	dopoptosub_at(cxstack, (plop))

PP(pp_wantarray)
{
    dVAR;
    dSP;
    I32 cxix;
    EXTEND(SP, 1);

    cxix = dopoptosub(cxstack_ix);
    if (cxix < 0)
	RETPUSHUNDEF;

    switch (cxstack[cxix].blk_gimme) {
    case G_ARRAY:
	RETPUSHYES;
    case G_SCALAR:
	RETPUSHNO;
    default:
	RETPUSHUNDEF;
    }
}

PP(pp_regcreset)
{
    dVAR;
    /* XXXX Should store the old value to allow for tie/overload - and
       restore in regcomp, where marked with XXXX. */
    PL_reginterp_cnt = 0;
    TAINT_NOT;
    return NORMAL;
}

PP(pp_regcomp)
{
    dVAR;
    dSP;
    register PMOP *pm = (PMOP*)cLOGOP->op_other;
    SV *tmpstr;
    REGEXP *re = NULL;

    /* prevent recompiling under /o and ithreads. */
#if defined(USE_ITHREADS)
    if (pm->op_pmflags & PMf_KEEP && PM_GETRE(pm)) {
	if (PL_op->op_flags & OPf_STACKED) {
	    dMARK;
	    SP = MARK;
	}
	else
	    (void)POPs;
	RETURN;
    }
#endif

#define tryAMAGICregexp(rx)			\
    STMT_START {				\
	if (SvROK(rx) && SvAMAGIC(rx)) {	\
	    SV *sv = AMG_CALLun(rx, regexp);	\
	    if (sv) {				\
		if (SvROK(sv))			\
		    sv = SvRV(sv);		\
		if (SvTYPE(sv) != SVt_REGEXP)	\
		    Perl_croak(aTHX_ "Overloaded qr did not return a REGEXP"); \
		rx = sv;			\
	    }					\
	}					\
    } STMT_END
	    

    if (PL_op->op_flags & OPf_STACKED) {
	/* multiple args; concatentate them */
	dMARK; dORIGMARK;
	tmpstr = PAD_SV(ARGTARG);
	sv_setpvs(tmpstr, "");
	while (++MARK <= SP) {
	    SV *msv = *MARK;
	    if (PL_amagic_generation) {
		SV *sv;

		tryAMAGICregexp(msv);

		if ((SvAMAGIC(tmpstr) || SvAMAGIC(msv)) &&
		    (sv = amagic_call(tmpstr, msv, concat_amg, AMGf_assign)))
		{
		   sv_setsv(tmpstr, sv);
		   continue;
		}
	    }
	    sv_catsv(tmpstr, msv);
	}
    	SvSETMAGIC(tmpstr);
	SP = ORIGMARK;
    }
    else {
	tmpstr = POPs;
	tryAMAGICregexp(tmpstr);
    }

#undef tryAMAGICregexp

    if (SvROK(tmpstr)) {
	SV * const sv = SvRV(tmpstr);
	if (SvTYPE(sv) == SVt_REGEXP)
	    re = (REGEXP*) sv;
    }
    else if (SvTYPE(tmpstr) == SVt_REGEXP)
	re = (REGEXP*) tmpstr;

    if (re) {
	/* The match's LHS's get-magic might need to access this op's reg-
	   exp (as is sometimes the case with $';  see bug 70764).  So we
	   must call get-magic now before we replace the regexp. Hopeful-
	   ly this hack can be replaced with the approach described at
	   http://www.nntp.perl.org/group/perl.perl5.porters/2007/03
	   /msg122415.html some day. */
	OP *matchop = pm->op_next;
	SV *lhs;
	const bool was_tainted = PL_tainted;
	if (matchop->op_flags & OPf_STACKED)
	    lhs = TOPs;
	else if (matchop->op_private & OPpTARGET_MY)
	    lhs = PAD_SV(matchop->op_targ);
	else lhs = DEFSV;
	SvGETMAGIC(lhs);
	/* Restore the previous value of PL_tainted (which may have been
	   modified by get-magic), to avoid incorrectly setting the
	   RXf_TAINTED flag further down. */
	PL_tainted = was_tainted;

	re = reg_temp_copy(NULL, re);
	ReREFCNT_dec(PM_GETRE(pm));
	PM_SETRE(pm, re);
    }
    else {
	STRLEN len;
	const char *t = SvOK(tmpstr) ? SvPV_const(tmpstr, len) : "";
	re = PM_GETRE(pm);
	assert (re != (REGEXP*) &PL_sv_undef);

	/* Check against the last compiled regexp. */
	if (!re || !RX_PRECOMP(re) || RX_PRELEN(re) != len ||
	    memNE(RX_PRECOMP(re), t, len))
	{
	    const regexp_engine *eng = re ? RX_ENGINE(re) : NULL;
            U32 pm_flags = pm->op_pmflags & PMf_COMPILETIME;
	    if (re) {
	        ReREFCNT_dec(re);
#ifdef USE_ITHREADS
		PM_SETRE(pm, (REGEXP*) &PL_sv_undef);
#else
		PM_SETRE(pm, NULL);	/* crucial if regcomp aborts */
#endif
	    } else if (PL_curcop->cop_hints_hash) {
	        SV *ptr = Perl_refcounted_he_fetch(aTHX_ PL_curcop->cop_hints_hash, 0,
				       "regcomp", 7, 0, 0);
                if (ptr && SvIOK(ptr) && SvIV(ptr))
                    eng = INT2PTR(regexp_engine*,SvIV(ptr));
	    }

	    if (PL_op->op_flags & OPf_SPECIAL)
		PL_reginterp_cnt = I32_MAX; /* Mark as safe.  */

	    if (DO_UTF8(tmpstr)) {
		assert (SvUTF8(tmpstr));
	    } else if (SvUTF8(tmpstr)) {
		/* 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 tmpstr.  */
		STRLEN len;
		const char *const p = SvPV(tmpstr, len);
		tmpstr = newSVpvn_flags(p, len, SVs_TEMP);
	    }

 		if (eng) 
	        PM_SETRE(pm, CALLREGCOMP_ENG(eng, tmpstr, pm_flags));
		else
	        PM_SETRE(pm, CALLREGCOMP(tmpstr, pm_flags));

	    PL_reginterp_cnt = 0;	/* XXXX Be extra paranoid - needed
					   inside tie/overload accessors.  */
	}
    }
    
    re = PM_GETRE(pm);

#ifndef INCOMPLETE_TAINTS
    if (PL_tainting) {
	if (PL_tainted)
	    RX_EXTFLAGS(re) |= RXf_TAINTED;
	else
	    RX_EXTFLAGS(re) &= ~RXf_TAINTED;
    }
#endif

    if (!RX_PRELEN(PM_GETRE(pm)) && PL_curpm)
	pm = PL_curpm;


#if !defined(USE_ITHREADS)
    /* can't change the optree at runtime either */
    /* PMf_KEEP is handled differently under threads to avoid these problems */
    if (pm->op_pmflags & PMf_KEEP) {
	pm->op_private &= ~OPpRUNTIME;	/* no point compiling again */
	cLOGOP->op_first->op_next = PL_op->op_next;
    }
#endif
    RETURN;
}

PP(pp_substcont)
{
    dVAR;
    dSP;
    register PERL_CONTEXT *cx = &cxstack[cxstack_ix];
    register PMOP * const pm = (PMOP*) cLOGOP->op_other;
    register SV * const dstr = cx->sb_dstr;
    register char *s = cx->sb_s;
    register char *m = cx->sb_m;
    char *orig = cx->sb_orig;
    register REGEXP * const rx = cx->sb_rx;
    SV *nsv = NULL;
    REGEXP *old = PM_GETRE(pm);
    if(old != rx) {
	if(old)
	    ReREFCNT_dec(old);
	PM_SETRE(pm,ReREFCNT_inc(rx));
    }

    rxres_restore(&cx->sb_rxres, rx);
    RX_MATCH_UTF8_set(rx, DO_UTF8(cx->sb_targ));

    if (cx->sb_iters++) {
	const I32 saviters = cx->sb_iters;
	if (cx->sb_iters > cx->sb_maxiters)
	    DIE(aTHX_ "Substitution loop");

	if (!(cx->sb_rxtainted & 2) && SvTAINTED(TOPs))
	    cx->sb_rxtainted |= 2;
	sv_catsv(dstr, POPs);
	/* XXX: adjust for positive offsets of \G for instance s/(.)\G//g with positive pos() */
	s -= RX_GOFS(rx);

	/* Are we done */
	if (CxONCE(cx) || s < orig ||
		!CALLREGEXEC(rx, s, cx->sb_strend, orig,
			     (s == m) + RX_GOFS(rx), cx->sb_targ, NULL,
			     ((cx->sb_rflags & REXEC_COPY_STR)
			      ? (REXEC_IGNOREPOS|REXEC_NOT_FIRST)
			      : (REXEC_COPY_STR|REXEC_IGNOREPOS|REXEC_NOT_FIRST))))
	{
	    SV * const targ = cx->sb_targ;

	    assert(cx->sb_strend >= s);
	    if(cx->sb_strend > s) {
		 if (DO_UTF8(dstr) && !SvUTF8(targ))
		      sv_catpvn_utf8_upgrade(dstr, s, cx->sb_strend - s, nsv);
		 else
		      sv_catpvn(dstr, s, cx->sb_strend - s);
	    }
	    cx->sb_rxtainted |= RX_MATCH_TAINTED(rx);

#ifdef PERL_OLD_COPY_ON_WRITE
	    if (SvIsCOW(targ)) {
		sv_force_normal_flags(targ, SV_COW_DROP_PV);
	    } else
#endif
	    {
		SvPV_free(targ);
	    }
	    SvPV_set(targ, SvPVX(dstr));
	    SvCUR_set(targ, SvCUR(dstr));
	    SvLEN_set(targ, SvLEN(dstr));
	    if (DO_UTF8(dstr))
		SvUTF8_on(targ);
	    SvPV_set(dstr, NULL);

	    TAINT_IF(cx->sb_rxtainted & 1);
	    mPUSHi(saviters - 1);

	    (void)SvPOK_only_UTF8(targ);
	    TAINT_IF(cx->sb_rxtainted);
	    SvSETMAGIC(targ);
	    SvTAINT(targ);

	    LEAVE_SCOPE(cx->sb_oldsave);
	    POPSUBST(cx);
	    RETURNOP(pm->op_next);
	}
	cx->sb_iters = saviters;
    }
    if (RX_MATCH_COPIED(rx) && RX_SUBBEG(rx) != orig) {
	m = s;
	s = orig;
	cx->sb_orig = orig = RX_SUBBEG(rx);
	s = orig + (m - s);
	cx->sb_strend = s + (cx->sb_strend - m);
    }
    cx->sb_m = m = RX_OFFS(rx)[0].start + orig;
    if (m > s) {
	if (DO_UTF8(dstr) && !SvUTF8(cx->sb_targ))
	    sv_catpvn_utf8_upgrade(dstr, s, m - s, nsv);
	else
	    sv_catpvn(dstr, s, m-s);
    }
    cx->sb_s = RX_OFFS(rx)[0].end + orig;
    { /* Update the pos() information. */
	SV * const sv = cx->sb_targ;
	MAGIC *mg;
	SvUPGRADE(sv, SVt_PVMG);
	if (!(mg = mg_find(sv, PERL_MAGIC_regex_global))) {
#ifdef PERL_OLD_COPY_ON_WRITE
	    if (SvIsCOW(sv))
		sv_force_normal_flags(sv, 0);
#endif
	    mg = sv_magicext(sv, NULL, PERL_MAGIC_regex_global, &PL_vtbl_mglob,
			     NULL, 0);
	}
	mg->mg_len = m - orig;
    }
    if (old != rx)
	(void)ReREFCNT_inc(rx);
    cx->sb_rxtainted |= RX_MATCH_TAINTED(rx);
    rxres_save(&cx->sb_rxres, rx);
    RETURNOP(pm->op_pmstashstartu.op_pmreplstart);
}

void
Perl_rxres_save(pTHX_ void **rsp, REGEXP *rx)
{
    UV *p = (UV*)*rsp;
    U32 i;

    PERL_ARGS_ASSERT_RXRES_SAVE;
    PERL_UNUSED_CONTEXT;

    if (!p || p[1] < RX_NPARENS(rx)) {
#ifdef PERL_OLD_COPY_ON_WRITE
	i = 7 + RX_NPARENS(rx) * 2;
#else
	i = 6 + RX_NPARENS(rx) * 2;
#endif
	if (!p)
	    Newx(p, i, UV);
	else
	    Renew(p, i, UV);
	*rsp = (void*)p;
    }

    *p++ = PTR2UV(RX_MATCH_COPIED(rx) ? RX_SUBBEG(rx) : NULL);
    RX_MATCH_COPIED_off(rx);

#ifdef PERL_OLD_COPY_ON_WRITE
    *p++ = PTR2UV(RX_SAVED_COPY(rx));
    RX_SAVED_COPY(rx) = NULL;
#endif

    *p++ = RX_NPARENS(rx);

    *p++ = PTR2UV(RX_SUBBEG(rx));
    *p++ = (UV)RX_SUBLEN(rx);
    for (i = 0; i <= RX_NPARENS(rx); ++i) {
	*p++ = (UV)RX_OFFS(rx)[i].start;
	*p++ = (UV)RX_OFFS(rx)[i].end;
    }
}

static void
S_rxres_restore(pTHX_ void **rsp, REGEXP *rx)
{
    UV *p = (UV*)*rsp;
    U32 i;

    PERL_ARGS_ASSERT_RXRES_RESTORE;
    PERL_UNUSED_CONTEXT;

    RX_MATCH_COPY_FREE(rx);
    RX_MATCH_COPIED_set(rx, *p);
    *p++ = 0;

#ifdef PERL_OLD_COPY_ON_WRITE
    if (RX_SAVED_COPY(rx))
	SvREFCNT_dec (RX_SAVED_COPY(rx));
    RX_SAVED_COPY(rx) = INT2PTR(SV*,*p);
    *p++ = 0;
#endif

    RX_NPARENS(rx) = *p++;

    RX_SUBBEG(rx) = INT2PTR(char*,*p++);
    RX_SUBLEN(rx) = (I32)(*p++);
    for (i = 0; i <= RX_NPARENS(rx); ++i) {
	RX_OFFS(rx)[i].start = (I32)(*p++);
	RX_OFFS(rx)[i].end = (I32)(*p++);
    }
}

static void
S_rxres_free(pTHX_ void **rsp)
{
    UV * const p = (UV*)*rsp;

    PERL_ARGS_ASSERT_RXRES_FREE;
    PERL_UNUSED_CONTEXT;

    if (p) {
#ifdef PERL_POISON
	void *tmp = INT2PTR(char*,*p);
	Safefree(tmp);
	if (*p)
	    PoisonFree(*p, 1, sizeof(*p));
#else
	Safefree(INT2PTR(char*,*p));
#endif
#ifdef PERL_OLD_COPY_ON_WRITE
	if (p[1]) {
	    SvREFCNT_dec (INT2PTR(SV*,p[1]));
	}
#endif
	Safefree(p);
	*rsp = NULL;
    }
}

PP(pp_formline)
{
    dVAR; dSP; dMARK; dORIGMARK;
    register SV * const tmpForm = *++MARK;
    register U32 *fpc;
    register char *t;
    const char *f;
    register I32 arg;
    register SV *sv = NULL;
    const char *item = NULL;
    I32 itemsize  = 0;
    I32 fieldsize = 0;
    I32 lines = 0;
    bool chopspace = (strchr(PL_chopset, ' ') != NULL);
    const char *chophere = NULL;
    char *linemark = NULL;
    NV value;
    bool gotsome = FALSE;
    STRLEN len;
    const STRLEN fudge = SvPOK(tmpForm)
			? (SvCUR(tmpForm) * (IN_BYTES ? 1 : 3) + 1) : 0;
    bool item_is_utf8 = FALSE;
    bool targ_is_utf8 = FALSE;
    SV * nsv = NULL;
    OP * parseres = NULL;
    const char *fmt;

    if (!SvMAGICAL(tmpForm) || !SvCOMPILED(tmpForm)) {
	if (SvREADONLY(tmpForm)) {
	    SvREADONLY_off(tmpForm);
	    parseres = doparseform(tmpForm);
	    SvREADONLY_on(tmpForm);
	}
	else
	    parseres = doparseform(tmpForm);
	if (parseres)
	    return parseres;
    }
    SvPV_force(PL_formtarget, len);
    if (DO_UTF8(PL_formtarget))
	targ_is_utf8 = TRUE;
    t = SvGROW(PL_formtarget, len + fudge + 1);  /* XXX SvCUR bad */
    t += len;
    f = SvPV_const(tmpForm, len);
    /* need to jump to the next word */
    fpc = (U32*)(f + len + WORD_ALIGN - SvCUR(tmpForm) % WORD_ALIGN);

    for (;;) {
	DEBUG_f( {
	    const char *name = "???";
	    arg = -1;
	    switch (*fpc) {
	    case FF_LITERAL:	arg = fpc[1]; name = "LITERAL";	break;
	    case FF_BLANK:	arg = fpc[1]; name = "BLANK";	break;
	    case FF_SKIP:	arg = fpc[1]; name = "SKIP";	break;
	    case FF_FETCH:	arg = fpc[1]; name = "FETCH";	break;
	    case FF_DECIMAL:	arg = fpc[1]; name = "DECIMAL";	break;

	    case FF_CHECKNL:	name = "CHECKNL";	break;
	    case FF_CHECKCHOP:	name = "CHECKCHOP";	break;
	    case FF_SPACE:	name = "SPACE";		break;
	    case FF_HALFSPACE:	name = "HALFSPACE";	break;
	    case FF_ITEM:	name = "ITEM";		break;
	    case FF_CHOP:	name = "CHOP";		break;
	    case FF_LINEGLOB:	name = "LINEGLOB";	break;
	    case FF_NEWLINE:	name = "NEWLINE";	break;
	    case FF_MORE:	name = "MORE";		break;
	    case FF_LINEMARK:	name = "LINEMARK";	break;
	    case FF_END:	name = "END";		break;
	    case FF_0DECIMAL:	name = "0DECIMAL";	break;
	    case FF_LINESNGL:	name = "LINESNGL";	break;
	    }
	    if (arg >= 0)
		PerlIO_printf(Perl_debug_log, "%-16s%ld\n", name, (long) arg);
	    else
		PerlIO_printf(Perl_debug_log, "%-16s\n", name);
	} );
	switch (*fpc++) {
	case FF_LINEMARK:
	    linemark = t;
	    lines++;
	    gotsome = FALSE;
	    break;

	case FF_LITERAL:
	    arg = *fpc++;
	    if (targ_is_utf8 && !SvUTF8(tmpForm)) {
		SvCUR_set(PL_formtarget, t - SvPVX_const(PL_formtarget));
		*t = '\0';
		sv_catpvn_utf8_upgrade(PL_formtarget, f, arg, nsv);
		t = SvEND(PL_formtarget);
		f += arg;
		break;
	    }
	    if (!targ_is_utf8 && DO_UTF8(tmpForm)) {
		SvCUR_set(PL_formtarget, t - SvPVX_const(PL_formtarget));
		*t = '\0';
		sv_utf8_upgrade_flags_grow(PL_formtarget, SV_GMAGIC, fudge + 1);
		t = SvEND(PL_formtarget);
		targ_is_utf8 = TRUE;
	    }
	    while (arg--)
		*t++ = *f++;
	    break;

	case FF_SKIP:
	    f += *fpc++;
	    break;

	case FF_FETCH:
	    arg = *fpc++;
	    f += arg;
	    fieldsize = arg;

	    if (MARK < SP)
		sv = *++MARK;
	    else {
		sv = &PL_sv_no;
		Perl_ck_warner(aTHX_ packWARN(WARN_SYNTAX), "Not enough format arguments");
	    }
	    break;

	case FF_CHECKNL:
	    {
		const char *send;
		const char *s = item = SvPV_const(sv, len);
		itemsize = len;
		if (DO_UTF8(sv)) {
		    itemsize = sv_len_utf8(sv);
		    if (itemsize != (I32)len) {
			I32 itembytes;
			if (itemsize > fieldsize) {
			    itemsize = fieldsize;
			    itembytes = itemsize;
			    sv_pos_u2b(sv, &itembytes, 0);
			}
			else
			    itembytes = len;
			send = chophere = s + itembytes;
			while (s < send) {
			    if (*s & ~31)
				gotsome = TRUE;
			    else if (*s == '\n')
				break;
			    s++;
			}
			item_is_utf8 = TRUE;
			itemsize = s - item;
			sv_pos_b2u(sv, &itemsize);
			break;
		    }
		}
		item_is_utf8 = FALSE;
		if (itemsize > fieldsize)
		    itemsize = fieldsize;
		send = chophere = s + itemsize;
		while (s < send) {
		    if (*s & ~31)
			gotsome = TRUE;
		    else if (*s == '\n')
			break;
		    s++;
		}
		itemsize = s - item;
		break;
	    }

	case FF_CHECKCHOP:
	    {
		const char *s = item = SvPV_const(sv, len);
		itemsize = len;
		if (DO_UTF8(sv)) {
		    itemsize = sv_len_utf8(sv);
		    if (itemsize != (I32)len) {
			I32 itembytes;
			if (itemsize <= fieldsize) {
			    const char *send = chophere = s + itemsize;
			    while (s < send) {
				if (*s == '\r') {
				    itemsize = s - item;
				    chophere = s;
				    break;
				}
				if (*s++ & ~31)
				    gotsome = TRUE;
			    }
			}
			else {
			    const char *send;
			    itemsize = fieldsize;
			    itembytes = itemsize;
			    sv_pos_u2b(sv, &itembytes, 0);
			    send = chophere = s + itembytes;
			    while (s < send || (s == send && isSPACE(*s))) {
				if (isSPACE(*s)) {
				    if (chopspace)
					chophere = s;
				    if (*s == '\r')
					break;
				}
				else {
				    if (*s & ~31)
					gotsome = TRUE;
				    if (strchr(PL_chopset, *s))
					chophere = s + 1;
				}
				s++;
			    }
			    itemsize = chophere - item;
			    sv_pos_b2u(sv, &itemsize);
			}
			item_is_utf8 = TRUE;
			break;
		    }
		}
		item_is_utf8 = FALSE;
		if (itemsize <= fieldsize) {
		    const char *const send = chophere = s + itemsize;
		    while (s < send) {
			if (*s == '\r') {
			    itemsize = s - item;
			    chophere = s;
			    break;
			}
			if (*s++ & ~31)
			    gotsome = TRUE;
		    }
		}
		else {
		    const char *send;
		    itemsize = fieldsize;
		    send = chophere = s + itemsize;
		    while (s < send || (s == send && isSPACE(*s))) {
			if (isSPACE(*s)) {
			    if (chopspace)
				chophere = s;
			    if (*s == '\r')
				break;
			}
			else {
			    if (*s & ~31)
				gotsome = TRUE;
			    if (strchr(PL_chopset, *s))
				chophere = s + 1;
			}
			s++;
		    }
		    itemsize = chophere - item;
		}
		break;
	    }

	case FF_SPACE:
	    arg = fieldsize - itemsize;
	    if (arg) {
		fieldsize -= arg;
		while (arg-- > 0)
		    *t++ = ' ';
	    }
	    break;

	case FF_HALFSPACE:
	    arg = fieldsize - itemsize;
	    if (arg) {
		arg /= 2;
		fieldsize -= arg;
		while (arg-- > 0)
		    *t++ = ' ';
	    }
	    break;

	case FF_ITEM:
	    {
		const char *s = item;
		arg = itemsize;
		if (item_is_utf8) {
		    if (!targ_is_utf8) {
			SvCUR_set(PL_formtarget, t - SvPVX_const(PL_formtarget));
			*t = '\0';
			sv_utf8_upgrade_flags_grow(PL_formtarget, SV_GMAGIC,
								    fudge + 1);
			t = SvEND(PL_formtarget);
			targ_is_utf8 = TRUE;
		    }
		    while (arg--) {
			if (UTF8_IS_CONTINUED(*s)) {
			    STRLEN skip = UTF8SKIP(s);
			    switch (skip) {
			    default:
				Move(s,t,skip,char);
				s += skip;
				t += skip;
				break;
			    case 7: *t++ = *s++;
			    case 6: *t++ = *s++;
			    case 5: *t++ = *s++;
			    case 4: *t++ = *s++;
			    case 3: *t++ = *s++;
			    case 2: *t++ = *s++;
			    case 1: *t++ = *s++;
			    }
			}
			else {
			    if ( !((*t++ = *s++) & ~31) )
				t[-1] = ' ';
			}
		    }
		    break;
		}
		if (targ_is_utf8 && !item_is_utf8) {
		    SvCUR_set(PL_formtarget, t - SvPVX_const(PL_formtarget));
		    *t = '\0';
		    sv_catpvn_utf8_upgrade(PL_formtarget, s, arg, nsv);
		    for (; t < SvEND(PL_formtarget); t++) {
#ifdef EBCDIC
			const int ch = *t;
			if (iscntrl(ch))
#else
			    if (!(*t & ~31))
#endif
				*t = ' ';
		    }
		    break;
		}
		while (arg--) {
#ifdef EBCDIC
		    const int ch = *t++ = *s++;
		    if (iscntrl(ch))
#else
			if ( !((*t++ = *s++) & ~31) )
#endif
			    t[-1] = ' ';
		}
		break;
	    }

	case FF_CHOP:
	    {
		const char *s = chophere;
		if (chopspace) {
		    while (isSPACE(*s))
			s++;
		}
		sv_chop(sv,s);
		SvSETMAGIC(sv);
		break;
	    }

	case FF_LINESNGL:
	    chopspace = 0;
	case FF_LINEGLOB:
	    {
		const bool oneline = fpc[-1] == FF_LINESNGL;
		const char *s = item = SvPV_const(sv, len);
		item_is_utf8 = DO_UTF8(sv);
		itemsize = len;
		if (itemsize) {
		    STRLEN to_copy = itemsize;
		    const char *const send = s + len;
		    const U8 *source = (const U8 *) s;
		    U8 *tmp = NULL;

		    gotsome = TRUE;
		    chophere = s + itemsize;
		    while (s < send) {
			if (*s++ == '\n') {
			    if (oneline) {
				to_copy = s - SvPVX_const(sv) - 1;
				chophere = s;
				break;
			    } else {
				if (s == send) {
				    itemsize--;
				    to_copy--;
				} else
				    lines++;
			    }
			}
		    }
		    if (targ_is_utf8 && !item_is_utf8) {
			source = tmp = bytes_to_utf8(source, &to_copy);
			SvCUR_set(PL_formtarget,
				  t - SvPVX_const(PL_formtarget));
		    } else {
			if (item_is_utf8 && !targ_is_utf8) {
			    /* Upgrade targ to UTF8, and then we reduce it to
			       a problem we have a simple solution for.  */
			    SvCUR_set(PL_formtarget,
				      t - SvPVX_const(PL_formtarget));
			    targ_is_utf8 = TRUE;
			    /* Don't need get magic.  */
			    sv_utf8_upgrade_nomg(PL_formtarget);
			} else {
			    SvCUR_set(PL_formtarget,
				      t - SvPVX_const(PL_formtarget));
			}

			/* Easy. They agree.  */
			assert (item_is_utf8 == targ_is_utf8);
		    }
		    SvGROW(PL_formtarget,
			   SvCUR(PL_formtarget) + to_copy + fudge + 1);
		    t = SvPVX(PL_formtarget) + SvCUR(PL_formtarget);

		    Copy(source, t, to_copy, char);
		    t += to_copy;
		    SvCUR_set(PL_formtarget, SvCUR(PL_formtarget) + to_copy);
		    if (item_is_utf8) {
			if (SvGMAGICAL(sv)) {
			    /* Mustn't call sv_pos_b2u() as it does a second
			       mg_get(). Is this a bug? Do we need a _flags()
			       variant? */
			    itemsize = utf8_length(source, source + itemsize);
			} else {
			    sv_pos_b2u(sv, &itemsize);
			}
			assert(!tmp);
		    } else if (tmp) {
			Safefree(tmp);
		    }
		}
		break;
	    }

	case FF_0DECIMAL:
	    arg = *fpc++;
#if defined(USE_LONG_DOUBLE)
	    fmt = (const char *)
		((arg & 256) ?
		 "%#0*.*" PERL_PRIfldbl : "%0*.*" PERL_PRIfldbl);
#else
	    fmt = (const char *)
		((arg & 256) ?
		 "%#0*.*f"              : "%0*.*f");
#endif
	    goto ff_dec;
	case FF_DECIMAL:
	    arg = *fpc++;
#if defined(USE_LONG_DOUBLE)
 	    fmt = (const char *)
		((arg & 256) ? "%#*.*" PERL_PRIfldbl : "%*.*" PERL_PRIfldbl);
#else
            fmt = (const char *)
		((arg & 256) ? "%#*.*f"              : "%*.*f");
#endif
	ff_dec:
	    /* If the field is marked with ^ and the value is undefined,
	       blank it out. */
	    if ((arg & 512) && !SvOK(sv)) {
		arg = fieldsize;
		while (arg--)
		    *t++ = ' ';
		break;
	    }
	    gotsome = TRUE;
	    value = SvNV(sv);
	    /* overflow evidence */
	    if (num_overflow(value, fieldsize, arg)) {
	        arg = fieldsize;
		while (arg--)
		    *t++ = '#';
		break;
	    }
	    /* Formats aren't yet marked for locales, so assume "yes". */
	    {
		STORE_NUMERIC_STANDARD_SET_LOCAL();
		my_snprintf(t, SvLEN(PL_formtarget) - (t - SvPVX(PL_formtarget)), fmt, (int) fieldsize, (int) arg & 255, value);
		RESTORE_NUMERIC_STANDARD();
	    }
	    t += fieldsize;
	    break;

	case FF_NEWLINE:
	    f++;
	    while (t-- > linemark && *t == ' ') ;
	    t++;
	    *t++ = '\n';
	    break;

	case FF_BLANK:
	    arg = *fpc++;
	    if (gotsome) {
		if (arg) {		/* repeat until fields exhausted? */
		    *t = '\0';
		    SvCUR_set(PL_formtarget, t - SvPVX_const(PL_formtarget));
		    lines += FmLINES(PL_formtarget);
		    if (targ_is_utf8)
			SvUTF8_on(PL_formtarget);
		    FmLINES(PL_formtarget) = lines;
		    SP = ORIGMARK;
		    RETURNOP(cLISTOP->op_first);
		}
	    }
	    else {
		t = linemark;
		lines--;
	    }
	    break;

	case FF_MORE:
	    {
		const char *s = chophere;
		const char *send = item + len;
		if (chopspace) {
		    while (isSPACE(*s) && (s < send))
			s++;
		}
		if (s < send) {
		    char *s1;
		    arg = fieldsize - itemsize;
		    if (arg) {
			fieldsize -= arg;
			while (arg-- > 0)
			    *t++ = ' ';
		    }
		    s1 = t - 3;
		    if (strnEQ(s1,"   ",3)) {
			while (s1 > SvPVX_const(PL_formtarget) && isSPACE(s1[-1]))
			    s1--;
		    }
		    *s1++ = '.';
		    *s1++ = '.';
		    *s1++ = '.';
		}
		break;
	    }
	case FF_END:
	    *t = '\0';
	    SvCUR_set(PL_formtarget, t - SvPVX_const(PL_formtarget));
	    if (targ_is_utf8)
		SvUTF8_on(PL_formtarget);
	    FmLINES(PL_formtarget) += lines;
	    SP = ORIGMARK;
	    RETPUSHYES;
	}
    }
}

PP(pp_grepstart)
{
    dVAR; dSP;
    SV *src;

    if (PL_stack_base + *PL_markstack_ptr == SP) {
	(void)POPMARK;
	if (GIMME_V == G_SCALAR)
	    mXPUSHi(0);
	RETURNOP(PL_op->op_next->op_next);
    }
    PL_stack_sp = PL_stack_base + *PL_markstack_ptr + 1;
    pp_pushmark();				/* push dst */
    pp_pushmark();				/* push src */
    ENTER_with_name("grep");					/* enter outer scope */

    SAVETMPS;
    if (PL_op->op_private & OPpGREP_LEX)
	SAVESPTR(PAD_SVl(PL_op->op_targ));
    else
	SAVE_DEFSV;
    ENTER_with_name("grep_item");					/* enter inner scope */
    SAVEVPTR(PL_curpm);

    src = PL_stack_base[*PL_markstack_ptr];
    SvTEMP_off(src);
    if (PL_op->op_private & OPpGREP_LEX)
	PAD_SVl(PL_op->op_targ) = src;
    else
	DEFSV_set(src);

    PUTBACK;
    if (PL_op->op_type == OP_MAPSTART)
	pp_pushmark();			/* push top */
    return ((LOGOP*)PL_op->op_next)->op_other;
}

PP(pp_mapwhile)
{
    dVAR; dSP;
    const I32 gimme = GIMME_V;
    I32 items = (SP - PL_stack_base) - *PL_markstack_ptr; /* how many new items */
    I32 count;
    I32 shift;
    SV** src;
    SV** dst;

    /* first, move source pointer to the next item in the source list */
    ++PL_markstack_ptr[-1];

    /* if there are new items, push them into the destination list */
    if (items && gimme != G_VOID) {
	/* might need to make room back there first */
	if (items > PL_markstack_ptr[-1] - PL_markstack_ptr[-2]) {
	    /* XXX this implementation is very pessimal because the stack
	     * is repeatedly extended for every set of items.  Is possible
	     * to do this without any stack extension or copying at all
	     * by maintaining a separate list over which the map iterates
	     * (like foreach does). --gsar */

	    /* everything in the stack after the destination list moves
	     * towards the end the stack by the amount of room needed */
	    shift = items - (PL_markstack_ptr[-1] - PL_markstack_ptr[-2]);

	    /* items to shift up (accounting for the moved source pointer) */
	    count = (SP - PL_stack_base) - (PL_markstack_ptr[-1] - 1);

	    /* This optimization is by Ben Tilly and it does
	     * things differently from what Sarathy (gsar)
	     * is describing.  The downside of this optimization is
	     * that leaves "holes" (uninitialized and hopefully unused areas)
	     * to the Perl stack, but on the other hand this
	     * shouldn't be a problem.  If Sarathy's idea gets
	     * implemented, this optimization should become
	     * irrelevant.  --jhi */
            if (shift < count)
                shift = count; /* Avoid shifting too often --Ben Tilly */

	    EXTEND(SP,shift);
	    src = SP;
	    dst = (SP += shift);
	    PL_markstack_ptr[-1] += shift;
	    *PL_markstack_ptr += shift;
	    while (count--)
		*dst-- = *src--;
	}
	/* copy the new items down to the destination list */
	dst = PL_stack_base + (PL_markstack_ptr[-2] += items) - 1;
	if (gimme == G_ARRAY) {
	    while (items-- > 0)
		*dst-- = SvTEMP(TOPs) ? POPs : sv_mortalcopy(POPs);
	}
	else {
	    /* scalar context: we don't care about which values map returns
	     * (we use undef here). And so we certainly don't want to do mortal
	     * copies of meaningless values. */
	    while (items-- > 0) {
		(void)POPs;
		*dst-- = &PL_sv_undef;
	    }
	}
    }
    LEAVE_with_name("grep_item");					/* exit inner scope */

    /* All done yet? */
    if (PL_markstack_ptr[-1] > *PL_markstack_ptr) {

	(void)POPMARK;				/* pop top */
	LEAVE_with_name("grep");					/* exit outer scope */
	(void)POPMARK;				/* pop src */
	items = --*PL_markstack_ptr - PL_markstack_ptr[-1];
	(void)POPMARK;				/* pop dst */
	SP = PL_stack_base + POPMARK;		/* pop original mark */
	if (gimme == G_SCALAR) {
	    if (PL_op->op_private & OPpGREP_LEX) {
		SV* sv = sv_newmortal();
		sv_setiv(sv, items);
		PUSHs(sv);
	    }
	    else {
		dTARGET;
		XPUSHi(items);
	    }
	}
	else if (gimme == G_ARRAY)
	    SP += items;
	RETURN;
    }
    else {
	SV *src;

	ENTER_with_name("grep_item");					/* enter inner scope */
	SAVEVPTR(PL_curpm);

	/* set $_ to the new source item */
	src = PL_stack_base[PL_markstack_ptr[-1]];
	SvTEMP_off(src);
	if (PL_op->op_private & OPpGREP_LEX)
	    PAD_SVl(PL_op->op_targ) = src;
	else
	    DEFSV_set(src);

	RETURNOP(cLOGOP->op_other);
    }
}

/* Range stuff. */

PP(pp_range)
{
    dVAR;
    if (GIMME == G_ARRAY)
	return NORMAL;
    if (SvTRUEx(PAD_SV(PL_op->op_targ)))
	return cLOGOP->op_other;
    else
	return NORMAL;
}

PP(pp_flip)
{
    dVAR;
    dSP;

    if (GIMME == G_ARRAY) {
	RETURNOP(((LOGOP*)cUNOP->op_first)->op_other);
    }
    else {
	dTOPss;
	SV * const targ = PAD_SV(PL_op->op_targ);
	int flip = 0;

	if (PL_op->op_private & OPpFLIP_LINENUM) {
	    if (GvIO(PL_last_in_gv)) {
		flip = SvIV(sv) == (IV)IoLINES(GvIOp(PL_last_in_gv));
	    }
	    else {
		GV * const gv = gv_fetchpvs(".", GV_ADD|GV_NOTQUAL, SVt_PV);
		if (gv && GvSV(gv))
		    flip = SvIV(sv) == SvIV(GvSV(gv));
	    }
	} else {
	    flip = SvTRUE(sv);
	}
	if (flip) {
	    sv_setiv(PAD_SV(cUNOP->op_first->op_targ), 1);
	    if (PL_op->op_flags & OPf_SPECIAL) {
		sv_setiv(targ, 1);
		SETs(targ);
		RETURN;
	    }
	    else {
		sv_setiv(targ, 0);
		SP--;
		RETURNOP(((LOGOP*)cUNOP->op_first)->op_other);
	    }
	}
	sv_setpvs(TARG, "");
	SETs(targ);
	RETURN;
    }
}

/* This code tries to decide if "$left .. $right" should use the
   magical string increment, or if the range is numeric (we make
   an exception for .."0" [#18165]). AMS 20021031. */

#define RANGE_IS_NUMERIC(left,right) ( \
	SvNIOKp(left)  || (SvOK(left)  && !SvPOKp(left))  || \
	SvNIOKp(right) || (SvOK(right) && !SvPOKp(right)) || \
	(((!SvOK(left) && SvOK(right)) || ((!SvOK(left) || \
          looks_like_number(left)) && SvPOKp(left) && *SvPVX_const(left) != '0')) \
         && (!SvOK(right) || looks_like_number(right))))

PP(pp_flop)
{
    dVAR; dSP;

    if (GIMME == G_ARRAY) {
	dPOPPOPssrl;

	SvGETMAGIC(left);
	SvGETMAGIC(right);

	if (RANGE_IS_NUMERIC(left,right)) {
	    register IV i, j;
	    IV max;
	    if ((SvOK(left) && SvNV(left) < IV_MIN) ||
		(SvOK(right) && SvNV(right) > IV_MAX))
		DIE(aTHX_ "Range iterator outside integer range");
	    i = SvIV(left);
	    max = SvIV(right);
	    if (max >= i) {
		j = max - i + 1;
		EXTEND_MORTAL(j);
		EXTEND(SP, j);
	    }
	    else
		j = 0;
	    while (j--) {
		SV * const sv = sv_2mortal(newSViv(i++));
		PUSHs(sv);
	    }
	}
	else {
	    SV * const final = sv_mortalcopy(right);
	    STRLEN len;
	    const char * const tmps = SvPV_const(final, len);

	    SV *sv = sv_mortalcopy(left);
	    SvPV_force_nolen(sv);
	    while (!SvNIOKp(sv) && SvCUR(sv) <= len) {
		XPUSHs(sv);
	        if (strEQ(SvPVX_const(sv),tmps))
	            break;
		sv = sv_2mortal(newSVsv(sv));
		sv_inc(sv);
	    }
	}
    }
    else {
	dTOPss;
	SV * const targ = PAD_SV(cUNOP->op_first->op_targ);
	int flop = 0;
	sv_inc(targ);

	if (PL_op->op_private & OPpFLIP_LINENUM) {
	    if (GvIO(PL_last_in_gv)) {
		flop = SvIV(sv) == (IV)IoLINES(GvIOp(PL_last_in_gv));
	    }
	    else {
		GV * const gv = gv_fetchpvs(".", GV_ADD|GV_NOTQUAL, SVt_PV);
		if (gv && GvSV(gv)) flop = SvIV(sv) == SvIV(GvSV(gv));
	    }
	}
	else {
	    flop = SvTRUE(sv);
	}

	if (flop) {
	    sv_setiv(PAD_SV(((UNOP*)cUNOP->op_first)->op_first->op_targ), 0);
	    sv_catpvs(targ, "E0");
	}
	SETs(targ);
    }

    RETURN;
}

/* Control. */

static const char * const context_name[] = {
    "pseudo-block",
    NULL, /* CXt_WHEN never actually needs "block" */
    NULL, /* CXt_BLOCK never actually needs "block" */
    NULL, /* CXt_GIVEN never actually needs "block" */
    NULL, /* CXt_LOOP_FOR never actually needs "loop" */
    NULL, /* CXt_LOOP_PLAIN never actually needs "loop" */
    NULL, /* CXt_LOOP_LAZYSV never actually needs "loop" */
    NULL, /* CXt_LOOP_LAZYIV never actually needs "loop" */
    "subroutine",
    "format",
    "eval",
    "substitution",
};

STATIC I32
S_dopoptolabel(pTHX_ const char *label)
{
    dVAR;
    register I32 i;

    PERL_ARGS_ASSERT_DOPOPTOLABEL;

    for (i = cxstack_ix; i >= 0; i--) {
	register const PERL_CONTEXT * const cx = &cxstack[i];
	switch (CxTYPE(cx)) {
	case CXt_SUBST:
	case CXt_SUB:
	case CXt_FORMAT:
	case CXt_EVAL:
	case CXt_NULL:
	    Perl_ck_warner(aTHX_ packWARN(WARN_EXITING), "Exiting %s via %s",
			   context_name[CxTYPE(cx)], OP_NAME(PL_op));
	    if (CxTYPE(cx) == CXt_NULL)
		return -1;
	    break;
	case CXt_LOOP_LAZYIV:
	case CXt_LOOP_LAZYSV:
	case CXt_LOOP_FOR:
	case CXt_LOOP_PLAIN:
	  {
	    const char *cx_label = CxLABEL(cx);
	    if (!cx_label || strNE(label, cx_label) ) {
		DEBUG_l(Perl_deb(aTHX_ "(Skipping label #%ld %s)\n",
			(long)i, cx_label));
		continue;
	    }
	    DEBUG_l( Perl_deb(aTHX_ "(Found label #%ld %s)\n", (long)i, label));
	    return i;
	  }
	}
    }
    return i;
}


I32
Perl_dowantarray(pTHX)
{
    dVAR;
    const I32 gimme = block_gimme();
    return (gimme == G_VOID) ? G_SCALAR : gimme;
}

I32
Perl_block_gimme(pTHX)
{
    dVAR;
    const I32 cxix = dopoptosub(cxstack_ix);
    if (cxix < 0)
	return G_VOID;

    switch (cxstack[cxix].blk_gimme) {
    case G_VOID:
	return G_VOID;
    case G_SCALAR:
	return G_SCALAR;
    case G_ARRAY:
	return G_ARRAY;
    default:
	Perl_croak(aTHX_ "panic: bad gimme: %d\n", cxstack[cxix].blk_gimme);
	/* NOTREACHED */
	return 0;
    }
}

I32
Perl_is_lvalue_sub(pTHX)
{
    dVAR;
    const I32 cxix = dopoptosub(cxstack_ix);
    assert(cxix >= 0);  /* We should only be called from inside subs */

    if (CxLVAL(cxstack + cxix) && CvLVALUE(cxstack[cxix].blk_sub.cv))
	return CxLVAL(cxstack + cxix);
    else
	return 0;
}

STATIC I32
S_dopoptosub_at(pTHX_ const PERL_CONTEXT *cxstk, I32 startingblock)
{
    dVAR;
    I32 i;

    PERL_ARGS_ASSERT_DOPOPTOSUB_AT;

    for (i = startingblock; i >= 0; i--) {
	register const PERL_CONTEXT * const cx = &cxstk[i];
	switch (CxTYPE(cx)) {
	default:
	    continue;
	case CXt_EVAL:
	case CXt_SUB:
	case CXt_FORMAT:
	    DEBUG_l( Perl_deb(aTHX_ "(Found sub #%ld)\n", (long)i));
	    return i;
	}
    }
    return i;
}

STATIC I32
S_dopoptoeval(pTHX_ I32 startingblock)
{
    dVAR;
    I32 i;
    for (i = startingblock; i >= 0; i--) {
	register const PERL_CONTEXT *cx = &cxstack[i];
	switch (CxTYPE(cx)) {
	default:
	    continue;
	case CXt_EVAL:
	    DEBUG_l( Perl_deb(aTHX_ "(Found eval #%ld)\n", (long)i));
	    return i;
	}
    }
    return i;
}

STATIC I32
S_dopoptoloop(pTHX_ I32 startingblock)
{
    dVAR;
    I32 i;
    for (i = startingblock; i >= 0; i--) {
	register const PERL_CONTEXT * const cx = &cxstack[i];
	switch (CxTYPE(cx)) {
	case CXt_SUBST:
	case CXt_SUB:
	case CXt_FORMAT:
	case CXt_EVAL:
	case CXt_NULL:
	    Perl_ck_warner(aTHX_ packWARN(WARN_EXITING), "Exiting %s via %s",
			   context_name[CxTYPE(cx)], OP_NAME(PL_op));
	    if ((CxTYPE(cx)) == CXt_NULL)
		return -1;
	    break;
	case CXt_LOOP_LAZYIV:
	case CXt_LOOP_LAZYSV:
	case CXt_LOOP_FOR:
	case CXt_LOOP_PLAIN:
	    DEBUG_l( Perl_deb(aTHX_ "(Found loop #%ld)\n", (long)i));
	    return i;
	}
    }
    return i;
}

STATIC I32
S_dopoptogiven(pTHX_ I32 startingblock)
{
    dVAR;
    I32 i;
    for (i = startingblock; i >= 0; i--) {
	register const PERL_CONTEXT *cx = &cxstack[i];
	switch (CxTYPE(cx)) {
	default:
	    continue;
	case CXt_GIVEN:
	    DEBUG_l( Perl_deb(aTHX_ "(Found given #%ld)\n", (long)i));
	    return i;
	case CXt_LOOP_PLAIN:
	    assert(!CxFOREACHDEF(cx));
	    break;
	case CXt_LOOP_LAZYIV:
	case CXt_LOOP_LAZYSV:
	case CXt_LOOP_FOR:
	    if (CxFOREACHDEF(cx)) {
		DEBUG_l( Perl_deb(aTHX_ "(Found foreach #%ld)\n", (long)i));
		return i;
	    }
	}
    }
    return i;
}

STATIC I32
S_dopoptowhen(pTHX_ I32 startingblock)
{
    dVAR;
    I32 i;
    for (i = startingblock; i >= 0; i--) {
	register const PERL_CONTEXT *cx = &cxstack[i];
	switch (CxTYPE(cx)) {
	default:
	    continue;
	case CXt_WHEN:
	    DEBUG_l( Perl_deb(aTHX_ "(Found when #%ld)\n", (long)i));
	    return i;
	}
    }
    return i;
}

void
Perl_dounwind(pTHX_ I32 cxix)
{
    dVAR;
    I32 optype;

    while (cxstack_ix > cxix) {
	SV *sv;
        register PERL_CONTEXT *cx = &cxstack[cxstack_ix];
	DEBUG_l(PerlIO_printf(Perl_debug_log, "Unwinding block %ld, type %s\n",
			      (long) cxstack_ix, PL_block_type[CxTYPE(cx)]));
	/* Note: we don't need to restore the base context info till the end. */
	switch (CxTYPE(cx)) {
	case CXt_SUBST:
	    POPSUBST(cx);
	    continue;  /* not break */
	case CXt_SUB:
	    POPSUB(cx,sv);
	    LEAVESUB(sv);
	    break;
	case CXt_EVAL:
	    POPEVAL(cx);
	    break;
	case CXt_LOOP_LAZYIV:
	case CXt_LOOP_LAZYSV:
	case CXt_LOOP_FOR:
	case CXt_LOOP_PLAIN:
	    POPLOOP(cx);
	    break;
	case CXt_NULL:
	    break;
	case CXt_FORMAT:
	    POPFORMAT(cx);
	    break;
	}
	cxstack_ix--;
    }
    PERL_UNUSED_VAR(optype);
}

void
Perl_qerror(pTHX_ SV *err)
{
    dVAR;

    PERL_ARGS_ASSERT_QERROR;

    if (PL_in_eval)
	sv_catsv(ERRSV, err);
    else if (PL_errors)
	sv_catsv(PL_errors, err);
    else
	Perl_warn(aTHX_ "%"SVf, SVfARG(err));
    if (PL_parser)
	++PL_parser->error_count;
}

void
Perl_die_where(pTHX_ SV *msv)
{
    dVAR;

    if (PL_in_eval) {
	I32 cxix;
	I32 gimme;

	if (msv) {
	    if (PL_in_eval & EVAL_KEEPERR) {
                static const char prefix[] = "\t(in cleanup) ";
		SV * const err = ERRSV;
		const char *e = NULL;
		if (!SvPOK(err))
		    sv_setpvs(err,"");
		else if (SvCUR(err) >= sizeof(prefix)+SvCUR(msv)-1) {
		    STRLEN len;
		    STRLEN msglen;
		    const char* message = SvPV_const(msv, msglen);
		    e = SvPV_const(err, len);
		    e += len - msglen;
		    if (*e != *message || strNE(e,message))
			e = NULL;
		}
		if (!e) {
		    STRLEN start;
		    SvGROW(err, SvCUR(err)+sizeof(prefix)+SvCUR(msv));
		    sv_catpvn(err, prefix, sizeof(prefix)-1);
		    sv_catsv(err, msv);
		    start = SvCUR(err)-SvCUR(msv)-sizeof(prefix)+1;
		    Perl_ck_warner(aTHX_ packWARN(WARN_MISC), "%s",
				   SvPVX_const(err)+start);
		}
	    }
	    else {
		STRLEN msglen;
		const char* message = SvPV_const(msv, msglen);
		sv_setpvn(ERRSV, message, msglen);
		SvFLAGS(ERRSV) |= SvFLAGS(msv) & SVf_UTF8;
	    }
	}

	while ((cxix = dopoptoeval(cxstack_ix)) < 0
	       && PL_curstackinfo->si_prev)
	{
	    dounwind(-1);
	    POPSTACK;
	}

	if (cxix >= 0) {
	    I32 optype;
	    register PERL_CONTEXT *cx;
	    SV **newsp;

	    if (cxix < cxstack_ix)
		dounwind(cxix);

	    POPBLOCK(cx,PL_curpm);
	    if (CxTYPE(cx) != CXt_EVAL) {
		STRLEN msglen;
		const char* message = SvPVx_const( msv ? msv : ERRSV, msglen);
		PerlIO_write(Perl_error_log, (const char *)"panic: die ", 11);
		PerlIO_write(Perl_error_log, message, msglen);
		my_exit(1);
	    }
	    POPEVAL(cx);

	    if (gimme == G_SCALAR)
		*++newsp = &PL_sv_undef;
	    PL_stack_sp = newsp;

	    LEAVE;

	    /* LEAVE could clobber PL_curcop (see save_re_context())
	     * XXX it might be better to find a way to avoid messing with
	     * PL_curcop in save_re_context() instead, but this is a more
	     * minimal fix --GSAR */
	    PL_curcop = cx->blk_oldcop;

	    if (optype == OP_REQUIRE) {
                const char* const msg = SvPVx_nolen_const(ERRSV);
		SV * const nsv = cx->blk_eval.old_namesv;
                (void)hv_store(GvHVn(PL_incgv), SvPVX_const(nsv), SvCUR(nsv),
                               &PL_sv_undef, 0);
		DIE(aTHX_ "%sCompilation failed in require",
		    *msg ? msg : "Unknown error\n");
	    }
	    assert(CxTYPE(cx) == CXt_EVAL);
	    PL_restartop = cx->blk_eval.retop;
	    JMPENV_JUMP(3);
	    /* NOTREACHED */
	}
    }

    write_to_stderr( msv ? msv : ERRSV );
    my_failure_exit();
    /* NOTREACHED */
}

PP(pp_xor)
{
    dVAR; dSP; dPOPTOPssrl;
    if (SvTRUE(left) != SvTRUE(right))
	RETSETYES;
    else
	RETSETNO;
}

PP(pp_caller)
{
    dVAR;
    dSP;
    register I32 cxix = dopoptosub(cxstack_ix);
    register const PERL_CONTEXT *cx;
    register const PERL_CONTEXT *ccstack = cxstack;
    const PERL_SI *top_si = PL_curstackinfo;
    I32 gimme;
    const char *stashname;
    I32 count = 0;

    if (MAXARG)
	count = POPi;

    for (;;) {
	/* we may be in a higher stacklevel, so dig down deeper */
	while (cxix < 0 && top_si->si_type != PERLSI_MAIN) {
	    top_si = top_si->si_prev;
	    ccstack = top_si->si_cxstack;
	    cxix = dopoptosub_at(ccstack, top_si->si_cxix);
	}
	if (cxix < 0) {
	    if (GIMME != G_ARRAY) {
		EXTEND(SP, 1);
		RETPUSHUNDEF;
            }
	    RETURN;
	}
	/* caller() should not report the automatic calls to &DB::sub */
	if (PL_DBsub && GvCV(PL_DBsub) && cxix >= 0 &&
		ccstack[cxix].blk_sub.cv == GvCV(PL_DBsub))
	    count++;
	if (!count--)
	    break;
	cxix = dopoptosub_at(ccstack, cxix - 1);
    }

    cx = &ccstack[cxix];
    if (CxTYPE(cx) == CXt_SUB || CxTYPE(cx) == CXt_FORMAT) {
        const I32 dbcxix = dopoptosub_at(ccstack, cxix - 1);
	/* We expect that ccstack[dbcxix] is CXt_SUB, anyway, the
	   field below is defined for any cx. */
	/* caller() should not report the automatic calls to &DB::sub */
	if (PL_DBsub && GvCV(PL_DBsub) && dbcxix >= 0 && ccstack[dbcxix].blk_sub.cv == GvCV(PL_DBsub))
	    cx = &ccstack[dbcxix];
    }

    stashname = CopSTASHPV(cx->blk_oldcop);
    if (GIMME != G_ARRAY) {
        EXTEND(SP, 1);
	if (!stashname)
	    PUSHs(&PL_sv_undef);
	else {
	    dTARGET;
	    sv_setpv(TARG, stashname);
	    PUSHs(TARG);
	}
	RETURN;
    }

    EXTEND(SP, 11);

    if (!stashname)
	PUSHs(&PL_sv_undef);
    else
	mPUSHs(newSVpv(stashname, 0));
    mPUSHs(newSVpv(OutCopFILE(cx->blk_oldcop), 0));
    mPUSHi((I32)CopLINE(cx->blk_oldcop));
    if (!MAXARG)
	RETURN;
    if (CxTYPE(cx) == CXt_SUB || CxTYPE(cx) == CXt_FORMAT) {
	GV * const cvgv = CvGV(ccstack[cxix].blk_sub.cv);
	/* So is ccstack[dbcxix]. */
	if (isGV(cvgv)) {
	    SV * const sv = newSV(0);
	    gv_efullname3(sv, cvgv, NULL);
	    mPUSHs(sv);
	    PUSHs(boolSV(CxHASARGS(cx)));
	}
	else {
	    PUSHs(newSVpvs_flags("(unknown)", SVs_TEMP));
	    PUSHs(boolSV(CxHASARGS(cx)));
	}
    }
    else {
	PUSHs(newSVpvs_flags("(eval)", SVs_TEMP));
	mPUSHi(0);
    }
    gimme = (I32)cx->blk_gimme;
    if (gimme == G_VOID)
	PUSHs(&PL_sv_undef);
    else
	PUSHs(boolSV((gimme & G_WANT) == G_ARRAY));
    if (CxTYPE(cx) == CXt_EVAL) {
	/* eval STRING */
	if (CxOLD_OP_TYPE(cx) == OP_ENTEREVAL) {
	    PUSHs(cx->blk_eval.cur_text);
	    PUSHs(&PL_sv_no);
	}
	/* require */
	else if (cx->blk_eval.old_namesv) {
	    mPUSHs(newSVsv(cx->blk_eval.old_namesv));
	    PUSHs(&PL_sv_yes);
	}
	/* eval BLOCK (try blocks have old_namesv == 0) */
	else {
	    PUSHs(&PL_sv_undef);
	    PUSHs(&PL_sv_undef);
	}
    }
    else {
	PUSHs(&PL_sv_undef);
	PUSHs(&PL_sv_undef);
    }
    if (CxTYPE(cx) == CXt_SUB && CxHASARGS(cx)
	&& CopSTASH_eq(PL_curcop, PL_debstash))
    {
	AV * const ary = cx->blk_sub.argarray;
	const int off = AvARRAY(ary) - AvALLOC(ary);

	if (!PL_dbargs) {
	    PL_dbargs = GvAV(gv_AVadd(gv_fetchpvs("DB::args", GV_ADDMULTI,
						  SVt_PVAV)));
	    AvREAL_off(PL_dbargs);	/* XXX should be REIFY (see av.h) */
	}

	if (AvMAX(PL_dbargs) < AvFILLp(ary) + off)
	    av_extend(PL_dbargs, AvFILLp(ary) + off);
	Copy(AvALLOC(ary), AvARRAY(PL_dbargs), AvFILLp(ary) + 1 + off, SV*);
	AvFILLp(PL_dbargs) = AvFILLp(ary) + off;
    }
    /* XXX only hints propagated via op_private are currently
     * visible (others are not easily accessible, since they
     * use the global PL_hints) */
    mPUSHi(CopHINTS_get(cx->blk_oldcop));
    {
	SV * mask ;
	STRLEN * const old_warnings = cx->blk_oldcop->cop_warnings ;

	if  (old_warnings == pWARN_NONE ||
		(old_warnings == pWARN_STD && (PL_dowarn & G_WARN_ON) == 0))
            mask = newSVpvn(WARN_NONEstring, WARNsize) ;
        else if (old_warnings == pWARN_ALL ||
		  (old_warnings == pWARN_STD && PL_dowarn & G_WARN_ON)) {
	    /* Get the bit mask for $warnings::Bits{all}, because
	     * it could have been extended by warnings::register */
	    SV **bits_all;
	    HV * const bits = get_hv("warnings::Bits", 0);
	    if (bits && (bits_all=hv_fetchs(bits, "all", FALSE))) {
		mask = newSVsv(*bits_all);
	    }
	    else {
		mask = newSVpvn(WARN_ALLstring, WARNsize) ;
	    }
	}
        else
            mask = newSVpvn((char *) (old_warnings + 1), old_warnings[0]);
        mPUSHs(mask);
    }

    PUSHs(cx->blk_oldcop->cop_hints_hash ?
	  sv_2mortal(newRV_noinc(
				 MUTABLE_SV(Perl_refcounted_he_chain_2hv(aTHX_
					      cx->blk_oldcop->cop_hints_hash))))
	  : &PL_sv_undef);
    RETURN;
}

PP(pp_reset)
{
    dVAR;
    dSP;
    const char * const tmps = (MAXARG < 1) ? (const char *)"" : POPpconstx;
    sv_reset(tmps, CopSTASH(PL_curcop));
    PUSHs(&PL_sv_yes);
    RETURN;
}

/* like pp_nextstate, but used instead when the debugger is active */

PP(pp_dbstate)
{
    dVAR;
    PL_curcop = (COP*)PL_op;
    TAINT_NOT;		/* Each statement is presumed innocent */
    PL_stack_sp = PL_stack_base + cxstack[cxstack_ix].blk_oldsp;
    FREETMPS;

    if (PL_op->op_flags & OPf_SPECIAL /* breakpoint */
	    || SvIV(PL_DBsingle) || SvIV(PL_DBsignal) || SvIV(PL_DBtrace))
    {
	dSP;
	register PERL_CONTEXT *cx;
	const I32 gimme = G_ARRAY;
	U8 hasargs;
	GV * const gv = PL_DBgv;
	register CV * const cv = GvCV(gv);

	if (!cv)
	    DIE(aTHX_ "No DB::DB routine defined");

	if (CvDEPTH(cv) >= 1 && !(PL_debug & DEBUG_DB_RECURSE_FLAG))
	    /* don't do recursive DB::DB call */
	    return NORMAL;

	ENTER;
	SAVETMPS;

	SAVEI32(PL_debug);
	SAVESTACK_POS();
	PL_debug = 0;
	hasargs = 0;
	SPAGAIN;

	if (CvISXSUB(cv)) {
	    CvDEPTH(cv)++;
	    PUSHMARK(SP);
	    (void)(*CvXSUB(cv))(aTHX_ cv);
	    CvDEPTH(cv)--;
	    FREETMPS;
	    LEAVE;
	    return NORMAL;
	}
	else {
	    PUSHBLOCK(cx, CXt_SUB, SP);
	    PUSHSUB_DB(cx);
	    cx->blk_sub.retop = PL_op->op_next;
	    CvDEPTH(cv)++;
	    SAVECOMPPAD();
	    PAD_SET_CUR_NOSAVE(CvPADLIST(cv), 1);
	    RETURNOP(CvSTART(cv));
	}
    }
    else
	return NORMAL;
}

PP(pp_enteriter)
{
    dVAR; dSP; dMARK;
    register PERL_CONTEXT *cx;
    const I32 gimme = GIMME_V;
    SV **svp;
    U8 cxtype = CXt_LOOP_FOR;
#ifdef USE_ITHREADS
    PAD *iterdata;
#endif

    ENTER_with_name("loop1");
    SAVETMPS;

    if (PL_op->op_targ) {
	if (PL_op->op_private & OPpLVAL_INTRO) { /* for my $x (...) */
	    SvPADSTALE_off(PAD_SVl(PL_op->op_targ));
	    SAVESETSVFLAGS(PAD_SVl(PL_op->op_targ),
		    SVs_PADSTALE, SVs_PADSTALE);
	}
	SAVEPADSVANDMORTALIZE(PL_op->op_targ);
#ifndef USE_ITHREADS
	svp = &PAD_SVl(PL_op->op_targ);		/* "my" variable */
#else
	iterdata = NULL;
#endif
    }
    else {
	GV * const gv = MUTABLE_GV(POPs);
	svp = &GvSV(gv);			/* symbol table variable */
	SAVEGENERICSV(*svp);
	*svp = newSV(0);
#ifdef USE_ITHREADS
	iterdata = (PAD*)gv;
#endif
    }

    if (PL_op->op_private & OPpITER_DEF)
	cxtype |= CXp_FOR_DEF;

    ENTER_with_name("loop2");

    PUSHBLOCK(cx, cxtype, SP);
#ifdef USE_ITHREADS
    PUSHLOOP_FOR(cx, iterdata, MARK, PL_op->op_targ);
#else
    PUSHLOOP_FOR(cx, svp, MARK, 0);
#endif
    if (PL_op->op_flags & OPf_STACKED) {
	SV *maybe_ary = POPs;
	if (SvTYPE(maybe_ary) != SVt_PVAV) {
	    dPOPss;
	    SV * const right = maybe_ary;
	    SvGETMAGIC(sv);
	    SvGETMAGIC(right);
	    if (RANGE_IS_NUMERIC(sv,right)) {
		cx->cx_type &= ~CXTYPEMASK;
		cx->cx_type |= CXt_LOOP_LAZYIV;
		/* Make sure that no-one re-orders cop.h and breaks our
		   assumptions */
		assert(CxTYPE(cx) == CXt_LOOP_LAZYIV);
#ifdef NV_PRESERVES_UV
		if ((SvOK(sv) && ((SvNV(sv) < (NV)IV_MIN) ||
				  (SvNV(sv) > (NV)IV_MAX)))
			||
		    (SvOK(right) && ((SvNV(right) > (NV)IV_MAX) ||
				     (SvNV(right) < (NV)IV_MIN))))
#else
		if ((SvOK(sv) && ((SvNV(sv) <= (NV)IV_MIN)
				  ||
		                  ((SvNV(sv) > 0) &&
					((SvUV(sv) > (UV)IV_MAX) ||
					 (SvNV(sv) > (NV)UV_MAX)))))
			||
		    (SvOK(right) && ((SvNV(right) <= (NV)IV_MIN)
				     ||
				     ((SvNV(right) > 0) &&
					((SvUV(right) > (UV)IV_MAX) ||
					 (SvNV(right) > (NV)UV_MAX))))))
#endif
		    DIE(aTHX_ "Range iterator outside integer range");
		cx->blk_loop.state_u.lazyiv.cur = SvIV(sv);
		cx->blk_loop.state_u.lazyiv.end = SvIV(right);
#ifdef DEBUGGING
		/* for correct -Dstv display */
		cx->blk_oldsp = sp - PL_stack_base;
#endif
	    }
	    else {
		cx->cx_type &= ~CXTYPEMASK;
		cx->cx_type |= CXt_LOOP_LAZYSV;
		/* Make sure that no-one re-orders cop.h and breaks our
		   assumptions */
		assert(CxTYPE(cx) == CXt_LOOP_LAZYSV);
		cx->blk_loop.state_u.lazysv.cur = newSVsv(sv);
		cx->blk_loop.state_u.lazysv.end = right;
		SvREFCNT_inc(right);
		(void) SvPV_force_nolen(cx->blk_loop.state_u.lazysv.cur);
		/* This will do the upgrade to SVt_PV, and warn if the value
		   is uninitialised.  */
		(void) SvPV_nolen_const(right);
		/* Doing this avoids a check every time in pp_iter in pp_hot.c
		   to replace !SvOK() with a pointer to "".  */
		if (!SvOK(right)) {
		    SvREFCNT_dec(right);
		    cx->blk_loop.state_u.lazysv.end = &PL_sv_no;
		}
	    }
	}
	else /* SvTYPE(maybe_ary) == SVt_PVAV */ {
	    cx->blk_loop.state_u.ary.ary = MUTABLE_AV(maybe_ary);
	    SvREFCNT_inc(maybe_ary);
	    cx->blk_loop.state_u.ary.ix =
		(PL_op->op_private & OPpITER_REVERSED) ?
		AvFILL(cx->blk_loop.state_u.ary.ary) + 1 :
		-1;
	}
    }
    else { /* iterating over items on the stack */
	cx->blk_loop.state_u.ary.ary = NULL; /* means to use the stack */
	if (PL_op->op_private & OPpITER_REVERSED) {
	    cx->blk_loop.state_u.ary.ix = cx->blk_oldsp + 1;
	}
	else {
	    cx->blk_loop.state_u.ary.ix = MARK - PL_stack_base;
	}
    }

    RETURN;
}

PP(pp_enterloop)
{
    dVAR; dSP;
    register PERL_CONTEXT *cx;
    const I32 gimme = GIMME_V;

    ENTER_with_name("loop1");
    SAVETMPS;
    ENTER_with_name("loop2");

    PUSHBLOCK(cx, CXt_LOOP_PLAIN, SP);
    PUSHLOOP_PLAIN(cx, SP);

    RETURN;
}

PP(pp_leaveloop)
{
    dVAR; dSP;
    register PERL_CONTEXT *cx;
    I32 gimme;
    SV **newsp;
    PMOP *newpm;
    SV **mark;

    POPBLOCK(cx,newpm);
    assert(CxTYPE_is_LOOP(cx));
    mark = newsp;
    newsp = PL_stack_base + cx->blk_loop.resetsp;

    TAINT_NOT;
    if (gimme == G_VOID)
	NOOP;
    else if (gimme == G_SCALAR) {
	if (mark < SP)
	    *++newsp = sv_mortalcopy(*SP);
	else
	    *++newsp = &PL_sv_undef;
    }
    else {
	while (mark < SP) {
	    *++newsp = sv_mortalcopy(*++mark);
	    TAINT_NOT;		/* Each item is independent */
	}
    }
    SP = newsp;
    PUTBACK;

    POPLOOP(cx);	/* Stack values are safe: release loop vars ... */
    PL_curpm = newpm;	/* ... and pop $1 et al */

    LEAVE_with_name("loop2");
    LEAVE_with_name("loop1");

    return NORMAL;
}

PP(pp_return)
{
    dVAR; dSP; dMARK;
    register PERL_CONTEXT *cx;
    bool popsub2 = FALSE;
    bool clear_errsv = FALSE;
    I32 gimme;
    SV **newsp;
    PMOP *newpm;
    I32 optype = 0;
    SV *sv;
    OP *retop = NULL;

    const I32 cxix = dopoptosub(cxstack_ix);

    if (cxix < 0) {
	if (CxMULTICALL(cxstack)) { /* In this case we must be in a
				     * sort block, which is a CXt_NULL
				     * not a CXt_SUB */
	    dounwind(0);
	    PL_stack_base[1] = *PL_stack_sp;
	    PL_stack_sp = PL_stack_base + 1;
	    return 0;
	}
	else
	    DIE(aTHX_ "Can't return outside a subroutine");
    }
    if (cxix < cxstack_ix)
	dounwind(cxix);

    if (CxMULTICALL(&cxstack[cxix])) {
	gimme = cxstack[cxix].blk_gimme;
	if (gimme == G_VOID)
	    PL_stack_sp = PL_stack_base;
	else if (gimme == G_SCALAR) {
	    PL_stack_base[1] = *PL_stack_sp;
	    PL_stack_sp = PL_stack_base + 1;
	}
	return 0;
    }

    POPBLOCK(cx,newpm);
    switch (CxTYPE(cx)) {
    case CXt_SUB:
	popsub2 = TRUE;
	retop = cx->blk_sub.retop;
	cxstack_ix++; /* preserve cx entry on stack for use by POPSUB */
	break;
    case CXt_EVAL:
	if (!(PL_in_eval & EVAL_KEEPERR))
	    clear_errsv = TRUE;
	POPEVAL(cx);
	retop = cx->blk_eval.retop;
	if (CxTRYBLOCK(cx))
	    break;
	lex_end();
	if (optype == OP_REQUIRE &&
	    (MARK == SP || (gimme == G_SCALAR && !SvTRUE(*SP))) )
	{
	    /* Unassume the success we assumed earlier. */
	    SV * const nsv = cx->blk_eval.old_namesv;
	    (void)hv_delete(GvHVn(PL_incgv), SvPVX_const(nsv), SvCUR(nsv), G_DISCARD);
	    DIE(aTHX_ "%"SVf" did not return a true value", SVfARG(nsv));
	}
	break;
    case CXt_FORMAT:
	POPFORMAT(cx);
	retop = cx->blk_sub.retop;
	break;
    default:
	DIE(aTHX_ "panic: return");
    }

    TAINT_NOT;
    if (gimme == G_SCALAR) {
	if (MARK < SP) {
	    if (popsub2) {
		if (cx->blk_sub.cv && CvDEPTH(cx->blk_sub.cv) > 1) {
		    if (SvTEMP(TOPs)) {
			*++newsp = SvREFCNT_inc(*SP);
			FREETMPS;
			sv_2mortal(*newsp);
		    }
		    else {
			sv = SvREFCNT_inc(*SP);	/* FREETMPS could clobber it */
			FREETMPS;
			*++newsp = sv_mortalcopy(sv);
			SvREFCNT_dec(sv);
		    }
		}
		else
		    *++newsp = (SvTEMP(*SP)) ? *SP : sv_mortalcopy(*SP);
	    }
	    else
		*++newsp = sv_mortalcopy(*SP);
	}
	else
	    *++newsp = &PL_sv_undef;
    }
    else if (gimme == G_ARRAY) {
	while (++MARK <= SP) {
	    *++newsp = (popsub2 && SvTEMP(*MARK))
			? *MARK : sv_mortalcopy(*MARK);
	    TAINT_NOT;		/* Each item is independent */
	}
    }
    PL_stack_sp = newsp;

    LEAVE;
    /* Stack values are safe: */
    if (popsub2) {
	cxstack_ix--;
	POPSUB(cx,sv);	/* release CV and @_ ... */
    }
    else
	sv = NULL;
    PL_curpm = newpm;	/* ... and pop $1 et al */

    LEAVESUB(sv);
    if (clear_errsv) {
	CLEAR_ERRSV();
    }
    return retop;
}

PP(pp_last)
{
    dVAR; dSP;
    I32 cxix;
    register PERL_CONTEXT *cx;
    I32 pop2 = 0;
    I32 gimme;
    I32 optype;
    OP *nextop = NULL;
    SV **newsp;
    PMOP *newpm;
    SV **mark;
    SV *sv = NULL;


    if (PL_op->op_flags & OPf_SPECIAL) {
	cxix = dopoptoloop(cxstack_ix);
	if (cxix < 0)
	    DIE(aTHX_ "Can't \"last\" outside a loop block");
    }
    else {
	cxix = dopoptolabel(cPVOP->op_pv);
	if (cxix < 0)
	    DIE(aTHX_ "Label not found for \"last %s\"", cPVOP->op_pv);
    }
    if (cxix < cxstack_ix)
	dounwind(cxix);

    POPBLOCK(cx,newpm);
    cxstack_ix++; /* temporarily protect top context */
    mark = newsp;
    switch (CxTYPE(cx)) {
    case CXt_LOOP_LAZYIV:
    case CXt_LOOP_LAZYSV:
    case CXt_LOOP_FOR:
    case CXt_LOOP_PLAIN:
	pop2 = CxTYPE(cx);
	newsp = PL_stack_base + cx->blk_loop.resetsp;
	nextop = cx->blk_loop.my_op->op_lastop->op_next;
	break;
    case CXt_SUB:
	pop2 = CXt_SUB;
	nextop = cx->blk_sub.retop;
	break;
    case CXt_EVAL:
	POPEVAL(cx);
	nextop = cx->blk_eval.retop;
	break;
    case CXt_FORMAT:
	POPFORMAT(cx);
	nextop = cx->blk_sub.retop;
	break;
    default:
	DIE(aTHX_ "panic: last");
    }

    TAINT_NOT;
    if (gimme == G_SCALAR) {
	if (MARK < SP)
	    *++newsp = ((pop2 == CXt_SUB) && SvTEMP(*SP))
			? *SP : sv_mortalcopy(*SP);
	else
	    *++newsp = &PL_sv_undef;
    }
    else if (gimme == G_ARRAY) {
	while (++MARK <= SP) {
	    *++newsp = ((pop2 == CXt_SUB) && SvTEMP(*MARK))
			? *MARK : sv_mortalcopy(*MARK);
	    TAINT_NOT;		/* Each item is independent */
	}
    }
    SP = newsp;
    PUTBACK;

    LEAVE;
    cxstack_ix--;
    /* Stack values are safe: */
    switch (pop2) {
    case CXt_LOOP_LAZYIV:
    case CXt_LOOP_PLAIN:
    case CXt_LOOP_LAZYSV:
    case CXt_LOOP_FOR:
	POPLOOP(cx);	/* release loop vars ... */
	LEAVE;
	break;
    case CXt_SUB:
	POPSUB(cx,sv);	/* release CV and @_ ... */
	break;
    }
    PL_curpm = newpm;	/* ... and pop $1 et al */

    LEAVESUB(sv);
    PERL_UNUSED_VAR(optype);
    PERL_UNUSED_VAR(gimme);
    return nextop;
}

PP(pp_next)
{
    dVAR;
    I32 cxix;
    register PERL_CONTEXT *cx;
    I32 inner;

    if (PL_op->op_flags & OPf_SPECIAL) {
	cxix = dopoptoloop(cxstack_ix);
	if (cxix < 0)
	    DIE(aTHX_ "Can't \"next\" outside a loop block");
    }
    else {
	cxix = dopoptolabel(cPVOP->op_pv);
	if (cxix < 0)
	    DIE(aTHX_ "Label not found for \"next %s\"", cPVOP->op_pv);
    }
    if (cxix < cxstack_ix)
	dounwind(cxix);

    /* clear off anything above the scope we're re-entering, but
     * save the rest until after a possible continue block */
    inner = PL_scopestack_ix;
    TOPBLOCK(cx);
    if (PL_scopestack_ix < inner)
	leave_scope(PL_scopestack[PL_scopestack_ix]);
    PL_curcop = cx->blk_oldcop;
    return CX_LOOP_NEXTOP_GET(cx);
}

PP(pp_redo)
{
    dVAR;
    I32 cxix;
    register PERL_CONTEXT *cx;
    I32 oldsave;
    OP* redo_op;

    if (PL_op->op_flags & OPf_SPECIAL) {
	cxix = dopoptoloop(cxstack_ix);
	if (cxix < 0)
	    DIE(aTHX_ "Can't \"redo\" outside a loop block");
    }
    else {
	cxix = dopoptolabel(cPVOP->op_pv);
	if (cxix < 0)
	    DIE(aTHX_ "Label not found for \"redo %s\"", cPVOP->op_pv);
    }
    if (cxix < cxstack_ix)
	dounwind(cxix);

    redo_op = cxstack[cxix].blk_loop.my_op->op_redoop;
    if (redo_op->op_type == OP_ENTER) {
	/* pop one less context to avoid $x being freed in while (my $x..) */
	cxstack_ix++;
	assert(CxTYPE(&cxstack[cxstack_ix]) == CXt_BLOCK);
	redo_op = redo_op->op_next;
    }

    TOPBLOCK(cx);
    oldsave = PL_scopestack[PL_scopestack_ix - 1];
    LEAVE_SCOPE(oldsave);
    FREETMPS;
    PL_curcop = cx->blk_oldcop;
    return redo_op;
}

STATIC OP *
S_dofindlabel(pTHX_ OP *o, const char *label, OP **opstack, OP **oplimit)
{
    dVAR;
    OP **ops = opstack;
    static const char too_deep[] = "Target of goto is too deeply nested";

    PERL_ARGS_ASSERT_DOFINDLABEL;

    if (ops >= oplimit)
	Perl_croak(aTHX_ too_deep);
    if (o->op_type == OP_LEAVE ||
	o->op_type == OP_SCOPE ||
	o->op_type == OP_LEAVELOOP ||
	o->op_type == OP_LEAVESUB ||
	o->op_type == OP_LEAVETRY)
    {
	*ops++ = cUNOPo->op_first;
	if (ops >= oplimit)
	    Perl_croak(aTHX_ too_deep);
    }
    *ops = 0;
    if (o->op_flags & OPf_KIDS) {
	OP *kid;
	/* First try all the kids at this level, since that's likeliest. */
	for (kid = cUNOPo->op_first; kid; kid = kid->op_sibling) {
	    if (kid->op_type == OP_NEXTSTATE || kid->op_type == OP_DBSTATE) {
		const char *kid_label = CopLABEL(kCOP);
		if (kid_label && strEQ(kid_label, label))
		    return kid;
	    }
	}
	for (kid = cUNOPo->op_first; kid; kid = kid->op_sibling) {
	    if (kid == PL_lastgotoprobe)
		continue;
	    if (kid->op_type == OP_NEXTSTATE || kid->op_type == OP_DBSTATE) {
	        if (ops == opstack)
		    *ops++ = kid;
		else if (ops[-1]->op_type == OP_NEXTSTATE ||
		         ops[-1]->op_type == OP_DBSTATE)
		    ops[-1] = kid;
		else
		    *ops++ = kid;
	    }
	    if ((o = dofindlabel(kid, label, ops, oplimit)))
		return o;
	}
    }
    *ops = 0;
    return 0;
}

PP(pp_goto)
{
    dVAR; dSP;
    OP *retop = NULL;
    I32 ix;
    register PERL_CONTEXT *cx;
#define GOTO_DEPTH 64
    OP *enterops[GOTO_DEPTH];
    const char *label = NULL;
    const bool do_dump = (PL_op->op_type == OP_DUMP);
    static const char must_have_label[] = "goto must have label";

    if (PL_op->op_flags & OPf_STACKED) {
	SV * const sv = POPs;

	/* This egregious kludge implements goto &subroutine */
	if (SvROK(sv) && SvTYPE(SvRV(sv)) == SVt_PVCV) {
	    I32 cxix;
	    register PERL_CONTEXT *cx;
	    CV *cv = MUTABLE_CV(SvRV(sv));
	    SV** mark;
	    I32 items = 0;
	    I32 oldsave;
	    bool reified = 0;

	retry:
	    if (!CvROOT(cv) && !CvXSUB(cv)) {
		const GV * const gv = CvGV(cv);
		if (gv) {
		    GV *autogv;
		    SV *tmpstr;
		    /* autoloaded stub? */
		    if (cv != GvCV(gv) && (cv = GvCV(gv)))
			goto retry;
		    autogv = gv_autoload4(GvSTASH(gv), GvNAME(gv),
					  GvNAMELEN(gv), FALSE);
		    if (autogv && (cv = GvCV(autogv)))
			goto retry;
		    tmpstr = sv_newmortal();
		    gv_efullname3(tmpstr, gv, NULL);
		    DIE(aTHX_ "Goto undefined subroutine &%"SVf"", SVfARG(tmpstr));
		}
		DIE(aTHX_ "Goto undefined subroutine");
	    }

	    /* First do some returnish stuff. */
	    SvREFCNT_inc_simple_void(cv); /* avoid premature free during unwind */
	    FREETMPS;
	    cxix = dopoptosub(cxstack_ix);
	    if (cxix < 0)
		DIE(aTHX_ "Can't goto subroutine outside a subroutine");
	    if (cxix < cxstack_ix)
		dounwind(cxix);
	    TOPBLOCK(cx);
	    SPAGAIN;
	    /* ban goto in eval: see <20050521150056.GC20213@iabyn.com> */
	    if (CxTYPE(cx) == CXt_EVAL) {
		if (CxREALEVAL(cx))
		    DIE(aTHX_ "Can't goto subroutine from an eval-string");
		else
		    DIE(aTHX_ "Can't goto subroutine from an eval-block");
	    }
	    else if (CxMULTICALL(cx))
		DIE(aTHX_ "Can't goto subroutine from a sort sub (or similar callback)");
	    if (CxTYPE(cx) == CXt_SUB && CxHASARGS(cx)) {
		/* put @_ back onto stack */
		AV* av = cx->blk_sub.argarray;

		items = AvFILLp(av) + 1;
		EXTEND(SP, items+1); /* @_ could have been extended. */
		Copy(AvARRAY(av), SP + 1, items, SV*);
		SvREFCNT_dec(GvAV(PL_defgv));
		GvAV(PL_defgv) = cx->blk_sub.savearray;
		CLEAR_ARGARRAY(av);
		/* abandon @_ if it got reified */
		if (AvREAL(av)) {
		    reified = 1;
		    SvREFCNT_dec(av);
		    av = newAV();
		    av_extend(av, items-1);
		    AvREIFY_only(av);
		    PAD_SVl(0) = MUTABLE_SV(cx->blk_sub.argarray = av);
		}
	    }
	    else if (CvISXSUB(cv)) {	/* put GvAV(defgv) back onto stack */
		AV* const av = GvAV(PL_defgv);
		items = AvFILLp(av) + 1;
		EXTEND(SP, items+1); /* @_ could have been extended. */
		Copy(AvARRAY(av), SP + 1, items, SV*);
	    }
	    mark = SP;
	    SP += items;
	    if (CxTYPE(cx) == CXt_SUB &&
		!(CvDEPTH(cx->blk_sub.cv) = cx->blk_sub.olddepth))
		SvREFCNT_dec(cx->blk_sub.cv);
	    oldsave = PL_scopestack[PL_scopestack_ix - 1];
	    LEAVE_SCOPE(oldsave);

	    /* Now do some callish stuff. */
	    SAVETMPS;
	    SAVEFREESV(cv); /* later, undo the 'avoid premature free' hack */
	    if (CvISXSUB(cv)) {
		OP* const retop = cx->blk_sub.retop;
		SV **newsp;
		I32 gimme;
		if (reified) {
		    I32 index;
		    for (index=0; index<items; index++)
			sv_2mortal(SP[-index]);
		}

		/* XS subs don't have a CxSUB, so pop it */
		POPBLOCK(cx, PL_curpm);
		/* Push a mark for the start of arglist */
		PUSHMARK(mark);
		PUTBACK;
		(void)(*CvXSUB(cv))(aTHX_ cv);
		LEAVE;
		return retop;
	    }
	    else {
		AV* const padlist = CvPADLIST(cv);
		if (CxTYPE(cx) == CXt_EVAL) {
		    PL_in_eval = CxOLD_IN_EVAL(cx);
		    PL_eval_root = cx->blk_eval.old_eval_root;
		    cx->cx_type = CXt_SUB;
		}
		cx->blk_sub.cv = cv;
		cx->blk_sub.olddepth = CvDEPTH(cv);

		CvDEPTH(cv)++;
		if (CvDEPTH(cv) < 2)
		    SvREFCNT_inc_simple_void_NN(cv);
		else {
		    if (CvDEPTH(cv) == PERL_SUB_DEPTH_WARN && ckWARN(WARN_RECURSION))
			sub_crush_depth(cv);
		    pad_push(padlist, CvDEPTH(cv));
		}
		SAVECOMPPAD();
		PAD_SET_CUR_NOSAVE(padlist, CvDEPTH(cv));
		if (CxHASARGS(cx))
		{
		    AV *const av = MUTABLE_AV(PAD_SVl(0));

		    cx->blk_sub.savearray = GvAV(PL_defgv);
		    GvAV(PL_defgv) = MUTABLE_AV(SvREFCNT_inc_simple(av));
		    CX_CURPAD_SAVE(cx->blk_sub);
		    cx->blk_sub.argarray = av;

		    if (items >= AvMAX(av) + 1) {
			SV **ary = AvALLOC(av);
			if (AvARRAY(av) != ary) {
			    AvMAX(av) += AvARRAY(av) - AvALLOC(av);
			    AvARRAY(av) = ary;
			}
			if (items >= AvMAX(av) + 1) {
			    AvMAX(av) = items - 1;
			    Renew(ary,items+1,SV*);
			    AvALLOC(av) = ary;
			    AvARRAY(av) = ary;
			}
		    }
		    ++mark;
		    Copy(mark,AvARRAY(av),items,SV*);
		    AvFILLp(av) = items - 1;
		    assert(!AvREAL(av));
		    if (reified) {
			/* transfer 'ownership' of refcnts to new @_ */
			AvREAL_on(av);
			AvREIFY_off(av);
		    }
		    while (items--) {
			if (*mark)
			    SvTEMP_off(*mark);
			mark++;
		    }
		}
		if (PERLDB_SUB) {	/* Checking curstash breaks DProf. */
		    Perl_get_db_sub(aTHX_ NULL, cv);
		    if (PERLDB_GOTO) {
			CV * const gotocv = get_cvs("DB::goto", 0);
			if (gotocv) {
			    PUSHMARK( PL_stack_sp );
			    call_sv(MUTABLE_SV(gotocv), G_SCALAR | G_NODEBUG);
			    PL_stack_sp--;
			}
		    }
		}
		RETURNOP(CvSTART(cv));
	    }
	}
	else {
	    label = SvPV_nolen_const(sv);
	    if (!(do_dump || *label))
		DIE(aTHX_ must_have_label);
	}
    }
    else if (PL_op->op_flags & OPf_SPECIAL) {
	if (! do_dump)
	    DIE(aTHX_ must_have_label);
    }
    else
	label = cPVOP->op_pv;

    if (label && *label) {
	OP *gotoprobe = NULL;
	bool leaving_eval = FALSE;
	bool in_block = FALSE;
	PERL_CONTEXT *last_eval_cx = NULL;

	/* find label */

	PL_lastgotoprobe = NULL;
	*enterops = 0;
	for (ix = cxstack_ix; ix >= 0; ix--) {
	    cx = &cxstack[ix];
	    switch (CxTYPE(cx)) {
	    case CXt_EVAL:
		leaving_eval = TRUE;
                if (!CxTRYBLOCK(cx)) {
		    gotoprobe = (last_eval_cx ?
				last_eval_cx->blk_eval.old_eval_root :
				PL_eval_root);
		    last_eval_cx = cx;
		    break;
                }
                /* else fall through */
	    case CXt_LOOP_LAZYIV:
	    case CXt_LOOP_LAZYSV:
	    case CXt_LOOP_FOR:
	    case CXt_LOOP_PLAIN:
	    case CXt_GIVEN:
	    case CXt_WHEN:
		gotoprobe = cx->blk_oldcop->op_sibling;
		break;
	    case CXt_SUBST:
		continue;
	    case CXt_BLOCK:
		if (ix) {
		    gotoprobe = cx->blk_oldcop->op_sibling;
		    in_block = TRUE;
		} else
		    gotoprobe = PL_main_root;
		break;
	    case CXt_SUB:
		if (CvDEPTH(cx->blk_sub.cv) && !CxMULTICALL(cx)) {
		    gotoprobe = CvROOT(cx->blk_sub.cv);
		    break;
		}
		/* FALL THROUGH */
	    case CXt_FORMAT:
	    case CXt_NULL:
		DIE(aTHX_ "Can't \"goto\" out of a pseudo block");
	    default:
		if (ix)
		    DIE(aTHX_ "panic: goto");
		gotoprobe = PL_main_root;
		break;
	    }
	    if (gotoprobe) {
		retop = dofindlabel(gotoprobe, label,
				    enterops, enterops + GOTO_DEPTH);
		if (retop)
		    break;
	    }
	    PL_lastgotoprobe = gotoprobe;
	}
	if (!retop)
	    DIE(aTHX_ "Can't find label %s", label);

	/* if we're leaving an eval, check before we pop any frames
           that we're not going to punt, otherwise the error
	   won't be caught */

	if (leaving_eval && *enterops && enterops[1]) {
	    I32 i;
            for (i = 1; enterops[i]; i++)
                if (enterops[i]->op_type == OP_ENTERITER)
                    DIE(aTHX_ "Can't \"goto\" into the middle of a foreach loop");
	}

	if (*enterops && enterops[1]) {
	    I32 i = enterops[1]->op_type == OP_ENTER && in_block ? 2 : 1;
	    if (enterops[i])
		deprecate("\"goto\" to jump into a construct");
	}

	/* pop unwanted frames */

	if (ix < cxstack_ix) {
	    I32 oldsave;

	    if (ix < 0)
		ix = 0;
	    dounwind(ix);
	    TOPBLOCK(cx);
	    oldsave = PL_scopestack[PL_scopestack_ix];
	    LEAVE_SCOPE(oldsave);
	}

	/* push wanted frames */

	if (*enterops && enterops[1]) {
	    OP * const oldop = PL_op;
	    ix = enterops[1]->op_type == OP_ENTER && in_block ? 2 : 1;
	    for (; enterops[ix]; ix++) {
		PL_op = enterops[ix];
		/* Eventually we may want to stack the needed arguments
		 * for each op.  For now, we punt on the hard ones. */
		if (PL_op->op_type == OP_ENTERITER)
		    DIE(aTHX_ "Can't \"goto\" into the middle of a foreach loop");
		CALL_FPTR(PL_op->op_ppaddr)(aTHX);
	    }
	    PL_op = oldop;
	}
    }

    if (do_dump) {
#ifdef VMS
	if (!retop) retop = PL_main_start;
#endif
	PL_restartop = retop;
	PL_do_undump = TRUE;

	my_unexec();

	PL_restartop = 0;		/* hmm, must be GNU unexec().. */
	PL_do_undump = FALSE;
    }

    RETURNOP(retop);
}

PP(pp_exit)
{
    dVAR;
    dSP;
    I32 anum;

    if (MAXARG < 1)
	anum = 0;
    else {
	anum = SvIVx(POPs);
#ifdef VMS
        if (anum == 1 && (PL_op->op_private & OPpEXIT_VMSISH))
	    anum = 0;
        VMSISH_HUSHED  = VMSISH_HUSHED || (PL_op->op_private & OPpHUSH_VMSISH);
#endif
    }
    PL_exit_flags |= PERL_EXIT_EXPECTED;
#ifdef PERL_MAD
    /* KLUDGE: disable exit 0 in BEGIN blocks when we're just compiling */
    if (anum || !(PL_minus_c && PL_madskills))
	my_exit(anum);
#else
    my_exit(anum);
#endif
    PUSHs(&PL_sv_undef);
    RETURN;
}

/* Eval. */

STATIC void
S_save_lines(pTHX_ AV *array, SV *sv)
{
    const char *s = SvPVX_const(sv);
    const char * const send = SvPVX_const(sv) + SvCUR(sv);
    I32 line = 1;

    PERL_ARGS_ASSERT_SAVE_LINES;

    while (s && s < send) {
	const char *t;
	SV * const tmpstr = newSV_type(SVt_PVMG);

	t = (const char *)memchr(s, '\n', send - s);
	if (t)
	    t++;
	else
	    t = send;

	sv_setpvn(tmpstr, s, t - s);
	av_store(array, line++, tmpstr);
	s = t;
    }
}

STATIC OP *
S_docatch(pTHX_ OP *o)
{
    dVAR;
    int ret;
    OP * const oldop = PL_op;
    dJMPENV;

#ifdef DEBUGGING
    assert(CATCH_GET == TRUE);
#endif
    PL_op = o;

    JMPENV_PUSH(ret);
    switch (ret) {
    case 0:
	assert(cxstack_ix >= 0);
	assert(CxTYPE(&cxstack[cxstack_ix]) == CXt_EVAL);
	cxstack[cxstack_ix].blk_eval.cur_top_env = PL_top_env;
 redo_body:
	CALLRUNOPS(aTHX);
	break;
    case 3:
	/* die caught by an inner eval - continue inner loop */

	/* NB XXX we rely on the old popped CxEVAL still being at the top
	 * of the stack; the way die_where() currently works, this
	 * assumption is valid. In theory The cur_top_env value should be
	 * returned in another global, the way retop (aka PL_restartop)
	 * is. */
	assert(CxTYPE(&cxstack[cxstack_ix+1]) == CXt_EVAL);

	if (PL_restartop
	    && cxstack[cxstack_ix+1].blk_eval.cur_top_env == PL_top_env)
	{
	    PL_op = PL_restartop;
	    PL_restartop = 0;
	    goto redo_body;
	}
	/* FALL THROUGH */
    default:
	JMPENV_POP;
	PL_op = oldop;
	JMPENV_JUMP(ret);
	/* NOTREACHED */
    }
    JMPENV_POP;
    PL_op = oldop;
    return NULL;
}

OP *
Perl_sv_compile_2op(pTHX_ SV *sv, OP** startop, const char *code, PAD** padp)
/* sv Text to convert to OP tree. */
/* startop op_free() this to undo. */
/* code Short string id of the caller. */
{
    /* FIXME - how much of this code is common with pp_entereval?  */
    dVAR; dSP;				/* Make POPBLOCK work. */
    PERL_CONTEXT *cx;
    SV **newsp;
    I32 gimme = G_VOID;
    I32 optype;
    OP dummy;
    char tbuf[TYPE_DIGITS(long) + 12 + 10];
    char *tmpbuf = tbuf;
    char *safestr;
    int runtime;
    CV* runcv = NULL;	/* initialise to avoid compiler warnings */
    STRLEN len;

    PERL_ARGS_ASSERT_SV_COMPILE_2OP;

    ENTER_with_name("eval");
    lex_start(sv, NULL, FALSE);
    SAVETMPS;
    /* switch to eval mode */

    if (IN_PERL_COMPILETIME) {
	SAVECOPSTASH_FREE(&PL_compiling);
	CopSTASH_set(&PL_compiling, PL_curstash);
    }
    if (PERLDB_NAMEEVAL && CopLINE(PL_curcop)) {
	SV * const sv = sv_newmortal();
	Perl_sv_setpvf(aTHX_ sv, "_<(%.10seval %lu)[%s:%"IVdf"]",
		       code, (unsigned long)++PL_evalseq,
		       CopFILE(PL_curcop), (IV)CopLINE(PL_curcop));
	tmpbuf = SvPVX(sv);
	len = SvCUR(sv);
    }
    else
	len = my_snprintf(tmpbuf, sizeof(tbuf), "_<(%.10s_eval %lu)", code,
			  (unsigned long)++PL_evalseq);
    SAVECOPFILE_FREE(&PL_compiling);
    CopFILE_set(&PL_compiling, tmpbuf+2);
    SAVECOPLINE(&PL_compiling);
    CopLINE_set(&PL_compiling, 1);
    /* XXX For C<eval "...">s within BEGIN {} blocks, this ends up
       deleting the eval's FILEGV from the stash before gv_check() runs
       (i.e. before run-time proper). To work around the coredump that
       ensues, we always turn GvMULTI_on for any globals that were
       introduced within evals. See force_ident(). GSAR 96-10-12 */
    safestr = savepvn(tmpbuf, len);
    SAVEDELETE(PL_defstash, safestr, len);
    SAVEHINTS();
#ifdef OP_IN_REGISTER
    PL_opsave = op;
#else
    SAVEVPTR(PL_op);
#endif

    /* we get here either during compilation, or via pp_regcomp at runtime */
    runtime = IN_PERL_RUNTIME;
    if (runtime)
	runcv = find_runcv(NULL);

    PL_op = &dummy;
    PL_op->op_type = OP_ENTEREVAL;
    PL_op->op_flags = 0;			/* Avoid uninit warning. */
    PUSHBLOCK(cx, CXt_EVAL|(IN_PERL_COMPILETIME ? 0 : CXp_REAL), SP);
    PUSHEVAL(cx, 0);

    if (runtime)
	(void) doeval(G_SCALAR, startop, runcv, PL_curcop->cop_seq);
    else
	(void) doeval(G_SCALAR, startop, PL_compcv, PL_cop_seqmax);
    POPBLOCK(cx,PL_curpm);
    POPEVAL(cx);

    (*startop)->op_type = OP_NULL;
    (*startop)->op_ppaddr = PL_ppaddr[OP_NULL];
    lex_end();
    /* XXX DAPM do this properly one year */
    *padp = MUTABLE_AV(SvREFCNT_inc_simple(PL_comppad));
    LEAVE_with_name("eval");
    if (IN_PERL_COMPILETIME)
	CopHINTS_set(&PL_compiling, PL_hints);
#ifdef OP_IN_REGISTER
    op = PL_opsave;
#endif
    PERL_UNUSED_VAR(newsp);
    PERL_UNUSED_VAR(optype);

    return PL_eval_start;
}


/*
=for apidoc find_runcv

Locate the CV corresponding to the currently executing sub or eval.
If db_seqp is non_null, skip CVs that are in the DB package and populate
*db_seqp with the cop sequence number at the point that the DB:: code was
entered. (allows debuggers to eval in the scope of the breakpoint rather
than in the scope of the debugger itself).

=cut
*/

CV*
Perl_find_runcv(pTHX_ U32 *db_seqp)
{
    dVAR;
    PERL_SI	 *si;

    if (db_seqp)
	*db_seqp = PL_curcop->cop_seq;
    for (si = PL_curstackinfo; si; si = si->si_prev) {
        I32 ix;
	for (ix = si->si_cxix; ix >= 0; ix--) {
	    const PERL_CONTEXT *cx = &(si->si_cxstack[ix]);
	    if (CxTYPE(cx) == CXt_SUB || CxTYPE(cx) == CXt_FORMAT) {
		CV * const cv = cx->blk_sub.cv;
		/* skip DB:: code */
		if (db_seqp && PL_debstash && CvSTASH(cv) == PL_debstash) {
		    *db_seqp = cx->blk_oldcop->cop_seq;
		    continue;
		}
		return cv;
	    }
	    else if (CxTYPE(cx) == CXt_EVAL && !CxTRYBLOCK(cx))
		return PL_compcv;
	}
    }
    return PL_main_cv;
}


/* Compile a require/do, an eval '', or a /(?{...})/.
 * In the last case, startop is non-null, and contains the address of
 * a pointer that should be set to the just-compiled code.
 * outside is the lexically enclosing CV (if any) that invoked us.
 * Returns a bool indicating whether the compile was successful; if so,
 * PL_eval_start contains the first op of the compiled ocde; otherwise,
 * pushes undef (also croaks if startop != NULL).
 */

STATIC bool
S_doeval(pTHX_ int gimme, OP** startop, CV* outside, U32 seq)
{
    dVAR; dSP;
    OP * const saveop = PL_op;

    PL_in_eval = ((saveop && saveop->op_type == OP_REQUIRE)
		  ? (EVAL_INREQUIRE | (PL_in_eval & EVAL_INEVAL))
		  : EVAL_INEVAL);

    PUSHMARK(SP);

    SAVESPTR(PL_compcv);
    PL_compcv = MUTABLE_CV(newSV_type(SVt_PVCV));
    CvEVAL_on(PL_compcv);
    assert(CxTYPE(&cxstack[cxstack_ix]) == CXt_EVAL);
    cxstack[cxstack_ix].blk_eval.cv = PL_compcv;

    CvOUTSIDE_SEQ(PL_compcv) = seq;
    CvOUTSIDE(PL_compcv) = MUTABLE_CV(SvREFCNT_inc_simple(outside));

    /* set up a scratch pad */

    CvPADLIST(PL_compcv) = pad_new(padnew_SAVE);
    PL_op = NULL; /* avoid PL_op and PL_curpad referring to different CVs */


    if (!PL_madskills)
	SAVEMORTALIZESV(PL_compcv);	/* must remain until end of current statement */

    /* make sure we compile in the right package */

    if (CopSTASH_ne(PL_curcop, PL_curstash)) {
	SAVESPTR(PL_curstash);
	PL_curstash = CopSTASH(PL_curcop);
    }
    /* XXX:ajgo do we really need to alloc an AV for begin/checkunit */
    SAVESPTR(PL_beginav);
    PL_beginav = newAV();
    SAVEFREESV(PL_beginav);
    SAVESPTR(PL_unitcheckav);
    PL_unitcheckav = newAV();
    SAVEFREESV(PL_unitcheckav);

#ifdef PERL_MAD
    SAVEBOOL(PL_madskills);
    PL_madskills = 0;
#endif

    /* try to compile it */

    PL_eval_root = NULL;
    PL_curcop = &PL_compiling;
    CopARYBASE_set(PL_curcop, 0);
    if (saveop && (saveop->op_type != OP_REQUIRE) && (saveop->op_flags & OPf_SPECIAL))
	PL_in_eval |= EVAL_KEEPERR;
    else
	CLEAR_ERRSV();
    if (yyparse() || PL_parser->error_count || !PL_eval_root) {
	SV **newsp;			/* Used by POPBLOCK. */
	PERL_CONTEXT *cx = &cxstack[cxstack_ix];
	I32 optype = 0;			/* Might be reset by POPEVAL. */
	const char *msg;

	PL_op = saveop;
	if (PL_eval_root) {
	    op_free(PL_eval_root);
	    PL_eval_root = NULL;
	}
	SP = PL_stack_base + POPMARK;		/* pop original mark */
	if (!startop) {
	    POPBLOCK(cx,PL_curpm);
	    POPEVAL(cx);
	}
	lex_end();
	LEAVE_with_name("eval"); /* pp_entereval knows about this LEAVE.  */

	msg = SvPVx_nolen_const(ERRSV);
	if (optype == OP_REQUIRE) {
	    const SV * const nsv = cx->blk_eval.old_namesv;
	    (void)hv_store(GvHVn(PL_incgv), SvPVX_const(nsv), SvCUR(nsv),
                          &PL_sv_undef, 0);
	    Perl_croak(aTHX_ "%sCompilation failed in require",
		       *msg ? msg : "Unknown error\n");
	}
	else if (startop) {
	    POPBLOCK(cx,PL_curpm);
	    POPEVAL(cx);
	    Perl_croak(aTHX_ "%sCompilation failed in regexp",
		       (*msg ? msg : "Unknown error\n"));
	}
	else {
	    if (!*msg) {
	        sv_setpvs(ERRSV, "Compilation error");
	    }
	}
	PERL_UNUSED_VAR(newsp);
	PUSHs(&PL_sv_undef);
	PUTBACK;
	return FALSE;
    }
    CopLINE_set(&PL_compiling, 0);
    if (startop) {
	*startop = PL_eval_root;
    } else
	SAVEFREEOP(PL_eval_root);

    /* Set the context for this new optree.
     * Propagate the context from the eval(). */
    if ((gimme & G_WANT) == G_VOID)
	scalarvoid(PL_eval_root);
    else if ((gimme & G_WANT) == G_ARRAY)
	list(PL_eval_root);
    else
	scalar(PL_eval_root);

    DEBUG_x(dump_eval());

    /* Register with debugger: */
    if (PERLDB_INTER && saveop && saveop->op_type == OP_REQUIRE) {
	CV * const cv = get_cvs("DB::postponed", 0);
	if (cv) {
	    dSP;
	    PUSHMARK(SP);
	    XPUSHs(MUTABLE_SV(CopFILEGV(&PL_compiling)));
	    PUTBACK;
	    call_sv(MUTABLE_SV(cv), G_DISCARD);
	}
    }

    if (PL_unitcheckav)
	call_list(PL_scopestack_ix, PL_unitcheckav);

    /* compiled okay, so do it */

    CvDEPTH(PL_compcv) = 1;
    SP = PL_stack_base + POPMARK;		/* pop original mark */
    PL_op = saveop;			/* The caller may need it. */
    PL_parser->lex_state = LEX_NOTPARSING;	/* $^S needs this. */

    PUTBACK;
    return TRUE;
}

STATIC PerlIO *
S_check_type_and_open(pTHX_ const char *name)
{
    Stat_t st;
    const int st_rc = PerlLIO_stat(name, &st);

    PERL_ARGS_ASSERT_CHECK_TYPE_AND_OPEN;

    if (st_rc < 0 || S_ISDIR(st.st_mode) || S_ISBLK(st.st_mode)) {
	return NULL;
    }

    return PerlIO_open(name, PERL_SCRIPT_MODE);
}

#ifndef PERL_DISABLE_PMC
STATIC PerlIO *
S_doopen_pm(pTHX_ const char *name, const STRLEN namelen)
{
    PerlIO *fp;

    PERL_ARGS_ASSERT_DOOPEN_PM;

    if (namelen > 3 && memEQs(name + namelen - 3, 3, ".pm")) {
	SV *const pmcsv = newSV(namelen + 2);
	char *const pmc = SvPVX(pmcsv);
	Stat_t pmcstat;

	memcpy(pmc, name, namelen);
	pmc[namelen] = 'c';
	pmc[namelen + 1] = '\0';

	if (PerlLIO_stat(pmc, &pmcstat) < 0) {
	    fp = check_type_and_open(name);
	}
	else {
	    fp = check_type_and_open(pmc);
	}
	SvREFCNT_dec(pmcsv);
    }
    else {
	fp = check_type_and_open(name);
    }
    return fp;
}
#else
#  define doopen_pm(name, namelen) check_type_and_open(name)
#endif /* !PERL_DISABLE_PMC */

PP(pp_require)
{
    dVAR; dSP;
    register PERL_CONTEXT *cx;
    SV *sv;
    const char *name;
    STRLEN len;
    char * unixname;
    STRLEN unixlen;
#ifdef VMS
    int vms_unixname = 0;
#endif
    const char *tryname = NULL;
    SV *namesv = NULL;
    const I32 gimme = GIMME_V;
    int filter_has_file = 0;
    PerlIO *tryrsfp = NULL;
    SV *filter_cache = NULL;
    SV *filter_state = NULL;
    SV *filter_sub = NULL;
    SV *hook_sv = NULL;
    SV *encoding;
    OP *op;

    sv = POPs;
    if ( (SvNIOKp(sv) || SvVOK(sv)) && PL_op->op_type != OP_DOFILE) {
	sv = new_version(sv);
	if (!sv_derived_from(PL_patchlevel, "version"))
	    upg_version(PL_patchlevel, TRUE);
	if (cUNOP->op_first->op_type == OP_CONST && cUNOP->op_first->op_private & OPpCONST_NOVER) {
	    if ( vcmp(sv,PL_patchlevel) <= 0 )
		DIE(aTHX_ "Perls since %"SVf" too modern--this is %"SVf", stopped",
		    SVfARG(vnormal(sv)), SVfARG(vnormal(PL_patchlevel)));
	}
	else {
	    if ( vcmp(sv,PL_patchlevel) > 0 ) {
		I32 first = 0;
		AV *lav;
		SV * const req = SvRV(sv);
		SV * const pv = *hv_fetchs(MUTABLE_HV(req), "original", FALSE);

		/* get the left hand term */
		lav = MUTABLE_AV(SvRV(*hv_fetchs(MUTABLE_HV(req), "version", FALSE)));

		first  = SvIV(*av_fetch(lav,0,0));
		if (   first > (int)PERL_REVISION    /* probably 'use 6.0' */
		    || hv_exists(MUTABLE_HV(req), "qv", 2 ) /* qv style */
		    || av_len(lav) > 1               /* FP with > 3 digits */
		    || strstr(SvPVX(pv),".0")        /* FP with leading 0 */
		   ) {
		    DIE(aTHX_ "Perl %"SVf" required--this is only "
		    	"%"SVf", stopped", SVfARG(vnormal(req)),
			SVfARG(vnormal(PL_patchlevel)));
		}
		else { /* probably 'use 5.10' or 'use 5.8' */
		    SV *hintsv;
		    I32 second = 0;

		    if (av_len(lav)>=1) 
			second = SvIV(*av_fetch(lav,1,0));

		    second /= second >= 600  ? 100 : 10;
		    hintsv = Perl_newSVpvf(aTHX_ "v%d.%d.0",
					   (int)first, (int)second);
		    upg_version(hintsv, TRUE);

		    DIE(aTHX_ "Perl %"SVf" required (did you mean %"SVf"?)"
		    	"--this is only %"SVf", stopped",
			SVfARG(vnormal(req)),
			SVfARG(vnormal(sv_2mortal(hintsv))),
			SVfARG(vnormal(PL_patchlevel)));
		}
	    }
	}

        /* We do this only with use, not require. */
	if (PL_compcv &&
	  /* If we request a version >= 5.9.5, load feature.pm with the
	   * feature bundle that corresponds to the required version. */
		vcmp(sv, sv_2mortal(upg_version(newSVnv(5.009005), FALSE))) >= 0) {
	    SV *const importsv = vnormal(sv);
	    *SvPVX_mutable(importsv) = ':';
	    ENTER_with_name("load_feature");
	    Perl_load_module(aTHX_ 0, newSVpvs("feature"), NULL, importsv, NULL);
	    LEAVE_with_name("load_feature");
	}
	/* If a version >= 5.11.0 is requested, strictures are on by default! */
	if (PL_compcv &&
		vcmp(sv, sv_2mortal(upg_version(newSVnv(5.011000), FALSE))) >= 0) {
	    PL_hints |= (HINT_STRICT_REFS | HINT_STRICT_SUBS | HINT_STRICT_VARS);
	}

	RETPUSHYES;
    }
    name = SvPV_const(sv, len);
    if (!(name && len > 0 && *name))
	DIE(aTHX_ "Null filename used");
    TAINT_PROPER("require");


#ifdef VMS
    /* The key in the %ENV hash is in the syntax of file passed as the argument
     * usually this is in UNIX format, but sometimes in VMS format, which
     * can result in a module being pulled in more than once.
     * To prevent this, the key must be stored in UNIX format if the VMS
     * name can be translated to UNIX.
     */
    if ((unixname = tounixspec(name, NULL)) != NULL) {
	unixlen = strlen(unixname);
	vms_unixname = 1;
    }
    else
#endif
    {
        /* if not VMS or VMS name can not be translated to UNIX, pass it
	 * through.
	 */
	unixname = (char *) name;
	unixlen = len;
    }
    if (PL_op->op_type == OP_REQUIRE) {
	SV * const * const svp = hv_fetch(GvHVn(PL_incgv),
					  unixname, unixlen, 0);
	if ( svp ) {
	    if (*svp != &PL_sv_undef)
		RETPUSHYES;
	    else
		DIE(aTHX_ "Attempt to reload %s aborted.\n"
			    "Compilation failed in require", unixname);
	}
    }

    /* prepare to compile file */

    if (path_is_absolute(name)) {
	tryname = name;
	tryrsfp = doopen_pm(name, len);
    }
    if (!tryrsfp) {
	AV * const ar = GvAVn(PL_incgv);
	I32 i;
#ifdef VMS
	if (vms_unixname)
#endif
	{
	    namesv = newSV_type(SVt_PV);
	    for (i = 0; i <= AvFILL(ar); i++) {
		SV * const dirsv = *av_fetch(ar, i, TRUE);

		if (SvTIED_mg((const SV *)ar, PERL_MAGIC_tied))
		    mg_get(dirsv);
		if (SvROK(dirsv)) {
		    int count;