[perl5.git] / scope.c

/*    scope.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.
 *
 */

/*
 * For the fashion of Minas Tirith was such that it was built on seven
 * levels...
 *
 *     [p.751 of _The Lord of the Rings_, V/i: "Minas Tirith"]
 */

/* This file contains functions to manipulate several of Perl's stacks;
 * in particular it contains code to push various types of things onto
 * the savestack, then to pop them off and perform the correct restorative
 * action for each one. This corresponds to the cleanup Perl does at
 * each scope exit.
 */

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

SV**
Perl_stack_grow(pTHX_ SV **sp, SV **p, SSize_t n)
{
    PERL_ARGS_ASSERT_STACK_GROW;

    PL_stack_sp = sp;
#ifndef STRESS_REALLOC
    av_extend(PL_curstack, (p - PL_stack_base) + (n) + 128);
#else
    av_extend(PL_curstack, (p - PL_stack_base) + (n) + 1);
#endif
    return PL_stack_sp;
}

#ifndef STRESS_REALLOC
#define GROW(old) ((old) * 3 / 2)
#else
#define GROW(old) ((old) + 1)
#endif

PERL_SI *
Perl_new_stackinfo(pTHX_ I32 stitems, I32 cxitems)
{
    PERL_SI *si;
    Newx(si, 1, PERL_SI);
    si->si_stack = newAV();
    AvREAL_off(si->si_stack);
    av_extend(si->si_stack, stitems > 0 ? stitems-1 : 0);
    AvALLOC(si->si_stack)[0] = &PL_sv_undef;
    AvFILLp(si->si_stack) = 0;
    si->si_prev = 0;
    si->si_next = 0;
    si->si_cxmax = cxitems - 1;
    si->si_cxix = -1;
    si->si_type = PERLSI_UNDEF;
    Newx(si->si_cxstack, cxitems, PERL_CONTEXT);
    /* Without any kind of initialising PUSHSUBST()
     * in pp_subst() will read uninitialised heap. */
    PoisonNew(si->si_cxstack, cxitems, PERL_CONTEXT);
    return si;
}

I32
Perl_cxinc(pTHX)
{
    const IV old_max = cxstack_max;
    cxstack_max = GROW(cxstack_max);
    Renew(cxstack, cxstack_max + 1, PERL_CONTEXT);
    /* Without any kind of initialising deep enough recursion
     * will end up reading uninitialised PERL_CONTEXTs. */
    PoisonNew(cxstack + old_max + 1, cxstack_max - old_max, PERL_CONTEXT);
    return cxstack_ix + 1;
}

void
Perl_push_scope(pTHX)
{
    if (UNLIKELY(PL_scopestack_ix == PL_scopestack_max)) {
	PL_scopestack_max = GROW(PL_scopestack_max);
	Renew(PL_scopestack, PL_scopestack_max, I32);
#ifdef DEBUGGING
	Renew(PL_scopestack_name, PL_scopestack_max, const char*);
#endif
    }
#ifdef DEBUGGING
    PL_scopestack_name[PL_scopestack_ix] = "unknown";
#endif
    PL_scopestack[PL_scopestack_ix++] = PL_savestack_ix;

}

void
Perl_pop_scope(pTHX)
{
    const I32 oldsave = PL_scopestack[--PL_scopestack_ix];
    LEAVE_SCOPE(oldsave);
}

I32 *
Perl_markstack_grow(pTHX)
{
    const I32 oldmax = PL_markstack_max - PL_markstack;
    const I32 newmax = GROW(oldmax);

    Renew(PL_markstack, newmax, I32);
    PL_markstack_max = PL_markstack + newmax;
    PL_markstack_ptr = PL_markstack + oldmax;
    return PL_markstack_ptr;
}

void
Perl_savestack_grow(pTHX)
{
    PL_savestack_max = GROW(PL_savestack_max) + 4;
    Renew(PL_savestack, PL_savestack_max, ANY);
}

void
Perl_savestack_grow_cnt(pTHX_ I32 need)
{
    PL_savestack_max = PL_savestack_ix + need;
    Renew(PL_savestack, PL_savestack_max, ANY);
}

#undef GROW

void
Perl_tmps_grow(pTHX_ SSize_t n)
{
#ifndef STRESS_REALLOC
    if (n < 128)
	n = (PL_tmps_max < 512) ? 128 : 512;
#endif
    PL_tmps_max = PL_tmps_ix + n + 1;
    Renew(PL_tmps_stack, PL_tmps_max, SV*);
}


void
Perl_free_tmps(pTHX)
{
    /* XXX should tmps_floor live in cxstack? */
    const SSize_t myfloor = PL_tmps_floor;
    while (PL_tmps_ix > myfloor) {      /* clean up after last statement */
	SV* const sv = PL_tmps_stack[PL_tmps_ix--];
#ifdef PERL_POISON
	PoisonWith(PL_tmps_stack + PL_tmps_ix + 1, 1, SV *, 0xAB);
#endif
	if (LIKELY(sv && sv != &PL_sv_undef)) {
	    SvTEMP_off(sv);
	    SvREFCNT_dec_NN(sv);		/* note, can modify tmps_ix!!! */
	}
    }
}

STATIC SV *
S_save_scalar_at(pTHX_ SV **sptr, const U32 flags)
{
    SV * osv;
    SV *sv;

    PERL_ARGS_ASSERT_SAVE_SCALAR_AT;

    osv = *sptr;
    sv  = (flags & SAVEf_KEEPOLDELEM) ? osv : (*sptr = newSV(0));

    if (SvTYPE(osv) >= SVt_PVMG && SvMAGIC(osv)) {
	if (SvGMAGICAL(osv)) {
	    SvFLAGS(osv) |= (SvFLAGS(osv) &
	       (SVp_IOK|SVp_NOK|SVp_POK)) >> PRIVSHIFT;
	}
	if (!(flags & SAVEf_KEEPOLDELEM))
	    mg_localize(osv, sv, cBOOL(flags & SAVEf_SETMAGIC));
    }

    return sv;
}

void
Perl_save_pushptrptr(pTHX_ void *const ptr1, void *const ptr2, const int type)
{
    dSS_ADD;
    SS_ADD_PTR(ptr1);
    SS_ADD_PTR(ptr2);
    SS_ADD_UV(type);
    SS_ADD_END(3);
}

SV *
Perl_save_scalar(pTHX_ GV *gv)
{
    SV ** const sptr = &GvSVn(gv);

    PERL_ARGS_ASSERT_SAVE_SCALAR;

    if (UNLIKELY(SvGMAGICAL(*sptr))) {
        PL_localizing = 1;
        (void)mg_get(*sptr);
        PL_localizing = 0;
    }
    save_pushptrptr(SvREFCNT_inc_simple(gv), SvREFCNT_inc(*sptr), SAVEt_SV);
    return save_scalar_at(sptr, SAVEf_SETMAGIC); /* XXX - FIXME - see #60360 */
}

/* Like save_sptr(), but also SvREFCNT_dec()s the new value.  Can be used to
 * restore a global SV to its prior contents, freeing new value. */
void
Perl_save_generic_svref(pTHX_ SV **sptr)
{
    PERL_ARGS_ASSERT_SAVE_GENERIC_SVREF;

    save_pushptrptr(sptr, SvREFCNT_inc(*sptr), SAVEt_GENERIC_SVREF);
}

/* Like save_pptr(), but also Safefree()s the new value if it is different
 * from the old one.  Can be used to restore a global char* to its prior
 * contents, freeing new value. */
void
Perl_save_generic_pvref(pTHX_ char **str)
{
    PERL_ARGS_ASSERT_SAVE_GENERIC_PVREF;

    save_pushptrptr(*str, str, SAVEt_GENERIC_PVREF);
}

/* Like save_generic_pvref(), but uses PerlMemShared_free() rather than Safefree().
 * Can be used to restore a shared global char* to its prior
 * contents, freeing new value. */
void
Perl_save_shared_pvref(pTHX_ char **str)
{
    PERL_ARGS_ASSERT_SAVE_SHARED_PVREF;

    save_pushptrptr(str, *str, SAVEt_SHARED_PVREF);
}

/* set the SvFLAGS specified by mask to the values in val */

void
Perl_save_set_svflags(pTHX_ SV* sv, U32 mask, U32 val)
{
    dSS_ADD;

    PERL_ARGS_ASSERT_SAVE_SET_SVFLAGS;

    SS_ADD_PTR(sv);
    SS_ADD_INT(mask);
    SS_ADD_INT(val);
    SS_ADD_UV(SAVEt_SET_SVFLAGS);
    SS_ADD_END(4);
}

void
Perl_save_gp(pTHX_ GV *gv, I32 empty)
{
    PERL_ARGS_ASSERT_SAVE_GP;

    save_pushptrptr(SvREFCNT_inc(gv), GvGP(gv), SAVEt_GP);

    if (empty) {
	GP *gp = Perl_newGP(aTHX_ gv);
	HV * const stash = GvSTASH(gv);
	bool isa_changed = 0;

	if (stash && HvENAME(stash)) {
	    if (GvNAMELEN(gv) == 3 && strnEQ(GvNAME(gv), "ISA", 3))
		isa_changed = TRUE;
	    else if (GvCVu(gv))
		/* taking a method out of circulation ("local")*/
                mro_method_changed_in(stash);
	}
	if (GvIOp(gv) && (IoFLAGS(GvIOp(gv)) & IOf_ARGV)) {
	    gp->gp_io = newIO();
	    IoFLAGS(gp->gp_io) |= IOf_ARGV|IOf_START;
	}
	GvGP_set(gv,gp);
	if (isa_changed) mro_isa_changed_in(stash);
    }
    else {
	gp_ref(GvGP(gv));
	GvINTRO_on(gv);
    }
}

AV *
Perl_save_ary(pTHX_ GV *gv)
{
    AV * const oav = GvAVn(gv);
    AV *av;

    PERL_ARGS_ASSERT_SAVE_ARY;

    if (UNLIKELY(!AvREAL(oav) && AvREIFY(oav)))
	av_reify(oav);
    save_pushptrptr(SvREFCNT_inc_simple_NN(gv), oav, SAVEt_AV);

    GvAV(gv) = NULL;
    av = GvAVn(gv);
    if (UNLIKELY(SvMAGIC(oav)))
	mg_localize(MUTABLE_SV(oav), MUTABLE_SV(av), TRUE);
    return av;
}

HV *
Perl_save_hash(pTHX_ GV *gv)
{
    HV *ohv, *hv;

    PERL_ARGS_ASSERT_SAVE_HASH;

    save_pushptrptr(
	SvREFCNT_inc_simple_NN(gv), (ohv = GvHVn(gv)), SAVEt_HV
    );

    GvHV(gv) = NULL;
    hv = GvHVn(gv);
    if (UNLIKELY(SvMAGIC(ohv)))
	mg_localize(MUTABLE_SV(ohv), MUTABLE_SV(hv), TRUE);
    return hv;
}

void
Perl_save_item(pTHX_ SV *item)
{
    SV * const sv = newSVsv(item);

    PERL_ARGS_ASSERT_SAVE_ITEM;

    save_pushptrptr(item, /* remember the pointer */
		    sv,   /* remember the value */
		    SAVEt_ITEM);
}

void
Perl_save_bool(pTHX_ bool *boolp)
{
    dSS_ADD;

    PERL_ARGS_ASSERT_SAVE_BOOL;

    SS_ADD_PTR(boolp);
    SS_ADD_UV(SAVEt_BOOL | (*boolp << 8));
    SS_ADD_END(2);
}

void
Perl_save_pushi32ptr(pTHX_ const I32 i, void *const ptr, const int type)
{
    dSS_ADD;

    SS_ADD_INT(i);
    SS_ADD_PTR(ptr);
    SS_ADD_UV(type);
    SS_ADD_END(3);
}

void
Perl_save_int(pTHX_ int *intp)
{
    const int i = *intp;
    UV type = ((UV)((UV)i << SAVE_TIGHT_SHIFT) | SAVEt_INT_SMALL);
    int size = 2;
    dSS_ADD;

    PERL_ARGS_ASSERT_SAVE_INT;

    if (UNLIKELY((int)(type >> SAVE_TIGHT_SHIFT) != i)) {
        SS_ADD_INT(i);
        type = SAVEt_INT;
        size++;
    }
    SS_ADD_PTR(intp);
    SS_ADD_UV(type);
    SS_ADD_END(size);
}

void
Perl_save_I8(pTHX_ I8 *bytep)
{
    dSS_ADD;

    PERL_ARGS_ASSERT_SAVE_I8;

    SS_ADD_PTR(bytep);
    SS_ADD_UV(SAVEt_I8 | ((UV)*bytep << 8));
    SS_ADD_END(2);
}

void
Perl_save_I16(pTHX_ I16 *intp)
{
    dSS_ADD;

    PERL_ARGS_ASSERT_SAVE_I16;

    SS_ADD_PTR(intp);
    SS_ADD_UV(SAVEt_I16 | ((UV)*intp << 8));
    SS_ADD_END(2);
}

void
Perl_save_I32(pTHX_ I32 *intp)
{
    const I32 i = *intp;
    UV type = ((I32)((U32)i << SAVE_TIGHT_SHIFT) | SAVEt_I32_SMALL);
    int size = 2;
    dSS_ADD;

    PERL_ARGS_ASSERT_SAVE_I32;

    if (UNLIKELY((I32)(type >> SAVE_TIGHT_SHIFT) != i)) {
        SS_ADD_INT(i);
        type = SAVEt_I32;
        size++;
    }
    SS_ADD_PTR(intp);
    SS_ADD_UV(type);
    SS_ADD_END(size);
}

void
Perl_save_strlen(pTHX_ STRLEN *ptr)
{
    dSS_ADD;

    PERL_ARGS_ASSERT_SAVE_STRLEN;

    SS_ADD_IV(*ptr);
    SS_ADD_PTR(ptr);
    SS_ADD_UV(SAVEt_STRLEN);
    SS_ADD_END(3);
}

/* Cannot use save_sptr() to store a char* since the SV** cast will
 * force word-alignment and we'll miss the pointer.
 */
void
Perl_save_pptr(pTHX_ char **pptr)
{
    PERL_ARGS_ASSERT_SAVE_PPTR;

    save_pushptrptr(*pptr, pptr, SAVEt_PPTR);
}

void
Perl_save_vptr(pTHX_ void *ptr)
{
    PERL_ARGS_ASSERT_SAVE_VPTR;

    save_pushptrptr(*(char**)ptr, ptr, SAVEt_VPTR);
}

void
Perl_save_sptr(pTHX_ SV **sptr)
{
    PERL_ARGS_ASSERT_SAVE_SPTR;

    save_pushptrptr(*sptr, sptr, SAVEt_SPTR);
}

void
Perl_save_padsv_and_mortalize(pTHX_ PADOFFSET off)
{
    dSS_ADD;

    ASSERT_CURPAD_ACTIVE("save_padsv");
    SS_ADD_PTR(SvREFCNT_inc_simple_NN(PL_curpad[off]));
    SS_ADD_PTR(PL_comppad);
    SS_ADD_UV((UV)off);
    SS_ADD_UV(SAVEt_PADSV_AND_MORTALIZE);
    SS_ADD_END(4);
}

void
Perl_save_hptr(pTHX_ HV **hptr)
{
    PERL_ARGS_ASSERT_SAVE_HPTR;

    save_pushptrptr(*hptr, hptr, SAVEt_HPTR);
}

void
Perl_save_aptr(pTHX_ AV **aptr)
{
    PERL_ARGS_ASSERT_SAVE_APTR;

    save_pushptrptr(*aptr, aptr, SAVEt_APTR);
}

void
Perl_save_pushptr(pTHX_ void *const ptr, const int type)
{
    dSS_ADD;
    SS_ADD_PTR(ptr);
    SS_ADD_UV(type);
    SS_ADD_END(2);
}

void
Perl_save_clearsv(pTHX_ SV **svp)
{
    const UV offset = svp - PL_curpad;
    const UV offset_shifted = offset << SAVE_TIGHT_SHIFT;

    PERL_ARGS_ASSERT_SAVE_CLEARSV;

    ASSERT_CURPAD_ACTIVE("save_clearsv");
    SvPADSTALE_off(*svp); /* mark lexical as active */
    if (UNLIKELY((offset_shifted >> SAVE_TIGHT_SHIFT) != offset)) {
	Perl_croak(aTHX_ "panic: pad offset %"UVuf" out of range (%p-%p)",
		   offset, svp, PL_curpad);
    }

    {
        dSS_ADD;
        SS_ADD_UV(offset_shifted | SAVEt_CLEARSV);
        SS_ADD_END(1);
    }
}

void
Perl_save_delete(pTHX_ HV *hv, char *key, I32 klen)
{
    PERL_ARGS_ASSERT_SAVE_DELETE;

    save_pushptri32ptr(key, klen, SvREFCNT_inc_simple(hv), SAVEt_DELETE);
}

void
Perl_save_hdelete(pTHX_ HV *hv, SV *keysv)
{
    STRLEN len;
    I32 klen;
    const char *key;

    PERL_ARGS_ASSERT_SAVE_HDELETE;

    key  = SvPV_const(keysv, len);
    klen = SvUTF8(keysv) ? -(I32)len : (I32)len;
    SvREFCNT_inc_simple_void_NN(hv);
    save_pushptri32ptr(savepvn(key, len), klen, hv, SAVEt_DELETE);
}

void
Perl_save_adelete(pTHX_ AV *av, SSize_t key)
{
    dSS_ADD;

    PERL_ARGS_ASSERT_SAVE_ADELETE;

    SvREFCNT_inc_void(av);
    SS_ADD_UV(key);
    SS_ADD_PTR(av);
    SS_ADD_IV(SAVEt_ADELETE);
    SS_ADD_END(3);
}

void
Perl_save_destructor(pTHX_ DESTRUCTORFUNC_NOCONTEXT_t f, void* p)
{
    dSS_ADD;
    PERL_ARGS_ASSERT_SAVE_DESTRUCTOR;

    SS_ADD_DPTR(f);
    SS_ADD_PTR(p);
    SS_ADD_UV(SAVEt_DESTRUCTOR);
    SS_ADD_END(3);
}

void
Perl_save_destructor_x(pTHX_ DESTRUCTORFUNC_t f, void* p)
{
    dSS_ADD;

    SS_ADD_DXPTR(f);
    SS_ADD_PTR(p);
    SS_ADD_UV(SAVEt_DESTRUCTOR_X);
    SS_ADD_END(3);
}

void
Perl_save_hints(pTHX)
{
    COPHH *save_cophh = cophh_copy(CopHINTHASH_get(&PL_compiling));
    if (PL_hints & HINT_LOCALIZE_HH) {
	HV *oldhh = GvHV(PL_hintgv);
	save_pushptri32ptr(oldhh, PL_hints, save_cophh, SAVEt_HINTS);
	GvHV(PL_hintgv) = NULL; /* in case copying dies */
	GvHV(PL_hintgv) = hv_copy_hints_hv(oldhh);
    } else {
	save_pushi32ptr(PL_hints, save_cophh, SAVEt_HINTS);
    }
}

static void
S_save_pushptri32ptr(pTHX_ void *const ptr1, const I32 i, void *const ptr2,
			const int type)
{
    dSS_ADD;
    SS_ADD_PTR(ptr1);
    SS_ADD_INT(i);
    SS_ADD_PTR(ptr2);
    SS_ADD_UV(type);
    SS_ADD_END(4);
}

void
Perl_save_aelem_flags(pTHX_ AV *av, SSize_t idx, SV **sptr,
			    const U32 flags)
{
    dSS_ADD;
    SV *sv;

    PERL_ARGS_ASSERT_SAVE_AELEM_FLAGS;

    SvGETMAGIC(*sptr);
    SS_ADD_PTR(SvREFCNT_inc_simple(av));
    SS_ADD_IV(idx);
    SS_ADD_PTR(SvREFCNT_inc(*sptr));
    SS_ADD_UV(SAVEt_AELEM);
    SS_ADD_END(4);
    /* The array needs to hold a reference count on its new element, so it
       must be AvREAL. */
    if (UNLIKELY(!AvREAL(av) && AvREIFY(av)))
	av_reify(av);
    save_scalar_at(sptr, flags); /* XXX - FIXME - see #60360 */
    if (flags & SAVEf_KEEPOLDELEM)
	return;
    sv = *sptr;
    /* If we're localizing a tied array element, this new sv
     * won't actually be stored in the array - so it won't get
     * reaped when the localize ends. Ensure it gets reaped by
     * mortifying it instead. DAPM */
    if (UNLIKELY(SvTIED_mg((const SV *)av, PERL_MAGIC_tied)))
	sv_2mortal(sv);
}

void
Perl_save_helem_flags(pTHX_ HV *hv, SV *key, SV **sptr, const U32 flags)
{
    SV *sv;

    PERL_ARGS_ASSERT_SAVE_HELEM_FLAGS;

    SvGETMAGIC(*sptr);
    {
        dSS_ADD;
        SS_ADD_PTR(SvREFCNT_inc_simple(hv));
        SS_ADD_PTR(newSVsv(key));
        SS_ADD_PTR(SvREFCNT_inc(*sptr));
        SS_ADD_UV(SAVEt_HELEM);
        SS_ADD_END(4);
    }
    save_scalar_at(sptr, flags);
    if (flags & SAVEf_KEEPOLDELEM)
	return;
    sv = *sptr;
    /* If we're localizing a tied hash element, this new sv
     * won't actually be stored in the hash - so it won't get
     * reaped when the localize ends. Ensure it gets reaped by
     * mortifying it instead. DAPM */
    if (UNLIKELY(SvTIED_mg((const SV *)hv, PERL_MAGIC_tied)))
	sv_2mortal(sv);
}

SV*
Perl_save_svref(pTHX_ SV **sptr)
{
    PERL_ARGS_ASSERT_SAVE_SVREF;

    SvGETMAGIC(*sptr);
    save_pushptrptr(sptr, SvREFCNT_inc(*sptr), SAVEt_SVREF);
    return save_scalar_at(sptr, SAVEf_SETMAGIC); /* XXX - FIXME - see #60360 */
}

I32
Perl_save_alloc(pTHX_ I32 size, I32 pad)
{
    const I32 start = pad + ((char*)&PL_savestack[PL_savestack_ix]
                          - (char*)PL_savestack);
    const UV elems = 1 + ((size + pad - 1) / sizeof(*PL_savestack));
    const UV elems_shifted = elems << SAVE_TIGHT_SHIFT;

    if (UNLIKELY((elems_shifted >> SAVE_TIGHT_SHIFT) != elems))
	Perl_croak(aTHX_
            "panic: save_alloc elems %"UVuf" out of range (%"IVdf"-%"IVdf")",
		   elems, (IV)size, (IV)pad);

    SSGROW(elems + 1);

    PL_savestack_ix += elems;
    SSPUSHUV(SAVEt_ALLOC | elems_shifted);
    return start;
}


#define ARG0_SV  MUTABLE_SV(arg0.any_ptr)
#define ARG0_AV  MUTABLE_AV(arg0.any_ptr)
#define ARG0_HV  MUTABLE_HV(arg0.any_ptr)
#define ARG0_PTR arg0.any_ptr
#define ARG0_PV  (char*)(arg0.any_ptr)
#define ARG0_PVP (char**)(arg0.any_ptr)
#define ARG0_I32 (arg0.any_i32)

#define ARG1_SV  MUTABLE_SV(arg1.any_ptr)
#define ARG1_AV  MUTABLE_AV(arg1.any_ptr)
#define ARG1_GV  MUTABLE_GV(arg1.any_ptr)
#define ARG1_SVP (SV**)(arg1.any_ptr)
#define ARG1_PVP (char**)(arg1.any_ptr)
#define ARG1_PTR arg1.any_ptr
#define ARG1_PV  (char*)(arg1.any_ptr)
#define ARG1_I32 (arg1.any_i32)

#define ARG2_SV  MUTABLE_SV(arg2.any_ptr)
#define ARG2_AV  MUTABLE_AV(arg2.any_ptr)
#define ARG2_HV  MUTABLE_HV(arg2.any_ptr)
#define ARG2_GV  MUTABLE_GV(arg2.any_ptr)
#define ARG2_PV  (char*)(arg2.any_ptr)

void
Perl_leave_scope(pTHX_ I32 base)
{
    /* Localise the effects of the TAINT_NOT inside the loop.  */
    bool was = TAINT_get;

    ANY arg0, arg1, arg2;

    /* these initialisations are logically unnecessary, but they shut up
     * spurious 'may be used uninitialized' compiler warnings */
    arg0.any_ptr = NULL;
    arg1.any_ptr = NULL;
    arg2.any_ptr = NULL;

    if (UNLIKELY(base < -1))
	Perl_croak(aTHX_ "panic: corrupt saved stack index %ld", (long) base);
    DEBUG_l(Perl_deb(aTHX_ "savestack: releasing items %ld -> %ld\n",
			(long)PL_savestack_ix, (long)base));
    while (PL_savestack_ix > base) {
	UV uv;
	U8 type;

        SV *refsv;
        SV **svp;

	TAINT_NOT;

        {
            I32 ix = PL_savestack_ix - 1;
            ANY *p = &PL_savestack[ix];
            uv = p->any_uv;
            type = (U8)uv & SAVE_MASK;
            if (type > SAVEt_ARG0_MAX) {
                ANY *p0 = p;
                arg0 = *--p;
                if (type > SAVEt_ARG1_MAX) {
                    arg1 = *--p;
                    if (type > SAVEt_ARG2_MAX) {
                        arg2 = *--p;
                    }
                }
                ix -= (p0 - p);
            }
            PL_savestack_ix = ix;
        }

	switch (type) {
	case SAVEt_ITEM:			/* normal string */
	    sv_replace(ARG1_SV, ARG0_SV);
            if (UNLIKELY(SvSMAGICAL(ARG1_SV))) {
                PL_localizing = 2;
                mg_set(ARG1_SV);
                PL_localizing = 0;
            }
	    break;

	    /* This would be a mathom, but Perl_save_svref() calls a static
	       function, S_save_scalar_at(), so has to stay in this file.  */
	case SAVEt_SVREF:			/* scalar reference */
	    svp = ARG1_SVP;
	    refsv = NULL; /* what to refcnt_dec */
	    goto restore_sv;

	case SAVEt_SV:				/* scalar reference */
	    svp = &GvSV(ARG1_GV);
	    refsv = ARG1_SV; /* what to refcnt_dec */
	restore_sv:
        {
	    SV * const sv = *svp;
	    *svp = ARG0_SV;
	    SvREFCNT_dec(sv);
            if (UNLIKELY(SvSMAGICAL(ARG0_SV))) {
                PL_localizing = 2;
                mg_set(ARG0_SV);
                PL_localizing = 0;
            }
	    SvREFCNT_dec_NN(ARG0_SV);
	    SvREFCNT_dec(refsv);
	    break;
        }
	case SAVEt_GENERIC_PVREF:		/* generic pv */
	    if (*ARG0_PVP != ARG1_PV) {
		Safefree(*ARG0_PVP);
		*ARG0_PVP = ARG1_PV;
	    }
	    break;
	case SAVEt_SHARED_PVREF:		/* shared pv */
	    if (*ARG1_PVP != ARG0_PV) {
#ifdef NETWARE
		PerlMem_free(*ARG1_PVP);
#else
		PerlMemShared_free(*ARG1_PVP);
#endif
		*ARG1_PVP = ARG0_PV;
	    }
	    break;
	case SAVEt_GVSV:			/* scalar slot in GV */
	    svp = &GvSV(ARG1_GV);
	    goto restore_svp;
	case SAVEt_GENERIC_SVREF:		/* generic sv */
            svp = ARG1_SVP;
	restore_svp:
        {
	    SV * const sv = *svp;
	    *svp = ARG0_SV;
	    SvREFCNT_dec(sv);
	    SvREFCNT_dec(ARG0_SV);
	    break;
        }
	case SAVEt_GVSLOT:			/* any slot in GV */
        {
            HV *const hv = GvSTASH(ARG2_GV);
	    svp = ARG1_SVP;
	    if (hv && HvENAME(hv) && (
		    (ARG0_SV && SvTYPE(ARG0_SV) == SVt_PVCV)
		 || (*svp && SvTYPE(*svp) == SVt_PVCV)
	       ))
	    {
		if ((char *)svp < (char *)GvGP(ARG2_GV)
		 || (char *)svp > (char *)GvGP(ARG2_GV) + sizeof(struct gp)
		 || GvREFCNT(ARG2_GV) > 2) /* "> 2" to ignore savestack's ref */
		    PL_sub_generation++;
		else mro_method_changed_in(hv);
	    }
	    goto restore_svp;
        }
	case SAVEt_AV:				/* array reference */
	    SvREFCNT_dec(GvAV(ARG1_GV));
	    GvAV(ARG1_GV) = ARG0_AV;
            if (UNLIKELY(SvSMAGICAL(ARG0_SV))) {
                PL_localizing = 2;
                mg_set(ARG0_SV);
                PL_localizing = 0;
            }
	    SvREFCNT_dec_NN(ARG1_GV);
	    break;
	case SAVEt_HV:				/* hash reference */
	    SvREFCNT_dec(GvHV(ARG1_GV));
	    GvHV(ARG1_GV) = ARG0_HV;
            if (UNLIKELY(SvSMAGICAL(ARG0_SV))) {
                PL_localizing = 2;
                mg_set(ARG0_SV);
                PL_localizing = 0;
            }
	    SvREFCNT_dec_NN(ARG1_GV);
	    break;
	case SAVEt_INT_SMALL:
	    *(int*)ARG0_PTR = (int)(uv >> SAVE_TIGHT_SHIFT);
	    break;
	case SAVEt_INT:				/* int reference */
	    *(int*)ARG0_PTR = (int)ARG1_I32;
	    break;
	case SAVEt_STRLEN:			/* STRLEN/size_t ref */
	    *(STRLEN*)ARG0_PTR = (STRLEN)arg1.any_iv;
	    break;
	case SAVEt_BOOL:			/* bool reference */
	    *(bool*)ARG0_PTR = cBOOL(uv >> 8);
#ifdef NO_TAINT_SUPPORT
            PERL_UNUSED_VAR(was);
#else
	    if (UNLIKELY(ARG0_PTR == &(TAINT_get))) {
		/* If we don't update <was>, to reflect what was saved on the
		 * stack for PL_tainted, then we will overwrite this attempt to
		 * restore it when we exit this routine.  Note that this won't
		 * work if this value was saved in a wider-than necessary type,
		 * such as I32 */
		was = *(bool*)ARG0_PTR;
	    }
#endif
	    break;
	case SAVEt_I32_SMALL:
	    *(I32*)ARG0_PTR = (I32)(uv >> SAVE_TIGHT_SHIFT);
	    break;
	case SAVEt_I32:				/* I32 reference */
#ifdef PERL_DEBUG_READONLY_OPS
            if (*(I32*)ARG0_PTR != ARG1_I32)
#endif
                *(I32*)ARG0_PTR = ARG1_I32;
	    break;
	case SAVEt_SPTR:			/* SV* reference */
	    *(SV**)(ARG0_PTR)= ARG1_SV;
	    break;
	case SAVEt_VPTR:			/* random* reference */
	case SAVEt_PPTR:			/* char* reference */
	    *ARG0_PVP = ARG1_PV;
	    break;
	case SAVEt_HPTR:			/* HV* reference */
	    *(HV**)ARG0_PTR = MUTABLE_HV(ARG1_PTR);
	    break;
	case SAVEt_APTR:			/* AV* reference */
	    *(AV**)ARG0_PTR = ARG1_AV;
	    break;
	case SAVEt_GP:				/* scalar reference */
        {
            HV *hv;
            /* possibly taking a method out of circulation */	
	    const bool had_method = !!GvCVu(ARG1_GV);
	    gp_free(ARG1_GV);
	    GvGP_set(ARG1_GV, (GP*)ARG0_PTR);
	    if ((hv=GvSTASH(ARG1_GV)) && HvENAME_get(hv)) {
	        if (   GvNAMELEN(ARG1_GV) == 3
                    && strnEQ(GvNAME(ARG1_GV), "ISA", 3)
                )
	            mro_isa_changed_in(hv);
                else if (had_method || GvCVu(ARG1_GV))
                    /* putting a method back into circulation ("local")*/	
                    gv_method_changed(ARG1_GV);
	    }
	    SvREFCNT_dec_NN(ARG1_GV);
	    break;
        }
	case SAVEt_FREESV:
	    SvREFCNT_dec(ARG0_SV);
	    break;
	case SAVEt_FREECOPHH:
	    cophh_free((COPHH *)ARG0_PTR);
	    break;
	case SAVEt_MORTALIZESV:
	    sv_2mortal(ARG0_SV);
	    break;
	case SAVEt_FREEOP:
	    ASSERT_CURPAD_LEGAL("SAVEt_FREEOP");
	    op_free((OP*)ARG0_PTR);
	    break;
	case SAVEt_FREEPV:
	    Safefree(ARG0_PTR);
	    break;

        {
          SV **svp;
          I32 i;
          SV *sv;

        case SAVEt_CLEARPADRANGE:
            i = (I32)((uv >> SAVE_TIGHT_SHIFT) & OPpPADRANGE_COUNTMASK);
	    svp = &PL_curpad[uv >>
                    (OPpPADRANGE_COUNTSHIFT + SAVE_TIGHT_SHIFT)] + i - 1;
            goto clearsv;
	case SAVEt_CLEARSV:
	    svp = &PL_curpad[uv >> SAVE_TIGHT_SHIFT];
            i = 1;
          clearsv:
            for (; i; i--, svp--) {
                sv = *svp;

                DEBUG_Xv(PerlIO_printf(Perl_debug_log,
             "Pad 0x%"UVxf"[0x%"UVxf"] clearsv: %ld sv=0x%"UVxf"<%"IVdf"> %s\n",
                    PTR2UV(PL_comppad), PTR2UV(PL_curpad),
                    (long)(svp-PL_curpad), PTR2UV(sv), (IV)SvREFCNT(sv),
                    (SvREFCNT(sv) <= 1 && !SvOBJECT(sv)) ? "clear" : "abandon"
                ));

                assert(SvPADMY(sv));

                /* Can clear pad variable in place? */
                if (SvREFCNT(sv) == 1 && !SvOBJECT(sv)) {

                    /* these flags are the union of all the relevant flags
                     * in the individual conditions within */
                    if (UNLIKELY(SvFLAGS(sv) & (
                            SVf_READONLY|SVf_PROTECT /*for SvREADONLY_off*/
                          | (SVs_GMG|SVs_SMG|SVs_RMG) /* SvMAGICAL() */
                          | SVf_OOK
                          | SVf_THINKFIRST)))
                    {
                        /* if a my variable that was made readonly is
                         * going out of scope, we want to remove the
                         * readonlyness so that it can go out of scope
                         * quietly
                         */
                        if (SvREADONLY(sv))
                            SvREADONLY_off(sv);

                        if (SvOOK(sv)) { /* OOK or HvAUX */
                            if (SvTYPE(sv) == SVt_PVHV)
                                Perl_hv_kill_backrefs(aTHX_ MUTABLE_HV(sv));
                            else
                                sv_backoff(sv);
                        }

                        if (SvMAGICAL(sv)) {
                            /* note that backrefs (either in HvAUX or magic)
                             * must be removed before other magic */
                            sv_unmagic(sv, PERL_MAGIC_backref);
                            if (SvTYPE(sv) != SVt_PVCV)
                                mg_free(sv);
                        }
                        if (SvTHINKFIRST(sv))
                            sv_force_normal_flags(sv, SV_IMMEDIATE_UNREF
                                                     |SV_COW_DROP_PV);

                    }
                    switch (SvTYPE(sv)) {
                    case SVt_NULL:
                        break;
                    case SVt_PVAV:
                        av_clear(MUTABLE_AV(sv));
                        break;
                    case SVt_PVHV:
                        hv_clear(MUTABLE_HV(sv));
                        break;
                    case SVt_PVCV:
                    {
                        HEK *hek =
			      CvNAMED(sv)
				? CvNAME_HEK((CV *)sv)
				: GvNAME_HEK(CvGV(sv));
                        assert(hek);
                        (void)share_hek_hek(hek);
                        cv_undef((CV *)sv);
                        CvNAME_HEK_set(sv, hek);
                        CvLEXICAL_on(sv);
                        break;
                    }
                    default:
                        /* This looks odd, but these two macros are for use in
                           expressions and finish with a trailing comma, so
                           adding a ; after them would be wrong. */
                        assert_not_ROK(sv)
                        assert_not_glob(sv)
                        SvFLAGS(sv) &=~ (SVf_OK|SVf_IVisUV|SVf_UTF8);
                        break;
                    }
                    SvPADSTALE_on(sv); /* mark as no longer live */
                }
                else {	/* Someone has a claim on this, so abandon it. */
                    assert(  SvFLAGS(sv) & SVs_PADMY);
                    assert(!(SvFLAGS(sv) & SVs_PADTMP));
                    switch (SvTYPE(sv)) {	/* Console ourselves with a new value */
                    case SVt_PVAV:	*svp = MUTABLE_SV(newAV());	break;
                    case SVt_PVHV:	*svp = MUTABLE_SV(newHV());	break;
                    case SVt_PVCV:
                    {
                        HEK * const hek = CvNAMED(sv)
                                             ? CvNAME_HEK((CV *)sv)
                                             : GvNAME_HEK(CvGV(sv));

                        /* Create a stub */
                        *svp = newSV_type(SVt_PVCV);

                        /* Share name */
                        CvNAME_HEK_set(*svp,
                                       share_hek_hek(hek));
                        CvLEXICAL_on(*svp);
                        break;
                    }
                    default:	*svp = newSV(0);		break;
                    }
                    SvREFCNT_dec_NN(sv); /* Cast current value to the winds. */
                    /* preserve pad nature, but also mark as not live
                     * for any closure capturing */
                    SvFLAGS(*svp) |= (SVs_PADMY|SVs_PADSTALE);
                }
            }
	    break;
        }
	case SAVEt_DELETE:
	    (void)hv_delete(ARG0_HV, ARG2_PV, ARG1_I32, G_DISCARD);
	    SvREFCNT_dec(ARG0_HV);
	    Safefree(arg2.any_ptr);
	    break;
	case SAVEt_ADELETE:
	    (void)av_delete(ARG0_AV, arg1.any_iv, G_DISCARD);
	    SvREFCNT_dec(ARG0_AV);
	    break;
	case SAVEt_DESTRUCTOR_X:
	    (*arg1.any_dxptr)(aTHX_ ARG0_PTR);
	    break;
	case SAVEt_REGCONTEXT:
	    /* regexp must have croaked */
	case SAVEt_ALLOC:
	    PL_savestack_ix -= uv >> SAVE_TIGHT_SHIFT;
	    break;
	case SAVEt_STACK_POS:		/* Position on Perl stack */
	    PL_stack_sp = PL_stack_base + arg0.any_i32;
	    break;
	case SAVEt_AELEM:		/* array element */
	    svp = av_fetch(ARG2_AV, arg1.any_iv, 1);
	    if (UNLIKELY(!AvREAL(ARG2_AV) && AvREIFY(ARG2_AV))) /* undo reify guard */
		SvREFCNT_dec(ARG0_SV);
	    if (LIKELY(svp)) {
		SV * const sv = *svp;
		if (LIKELY(sv && sv != &PL_sv_undef)) {
		    if (UNLIKELY(SvTIED_mg((const SV *)ARG2_AV, PERL_MAGIC_tied)))
			SvREFCNT_inc_void_NN(sv);
                    refsv = ARG2_SV;
		    goto restore_sv;
		}
	    }
	    SvREFCNT_dec(ARG2_AV);
	    SvREFCNT_dec(ARG0_SV);
	    break;
	case SAVEt_HELEM:		/* hash element */
        {
	    HE * const he = hv_fetch_ent(ARG2_HV, ARG1_SV, 1, 0);
	    SvREFCNT_dec(ARG1_SV);
	    if (LIKELY(he)) {
		const SV * const oval = HeVAL(he);
		if (LIKELY(oval && oval != &PL_sv_undef)) {
		    svp = &HeVAL(he);
		    if (UNLIKELY(SvTIED_mg((const SV *)ARG2_HV, PERL_MAGIC_tied)))
			SvREFCNT_inc_void(*svp);
		    refsv = ARG2_SV; /* what to refcnt_dec */
		    goto restore_sv;
		}
	    }
	    SvREFCNT_dec(ARG2_HV);
	    SvREFCNT_dec(ARG0_SV);
	    break;
        }
	case SAVEt_OP:
	    PL_op = (OP*)ARG0_PTR;
	    break;
	case SAVEt_HINTS:
	    if ((PL_hints & HINT_LOCALIZE_HH)) {
	      while (GvHV(PL_hintgv)) {
		HV *hv = GvHV(PL_hintgv);
		GvHV(PL_hintgv) = NULL;
		SvREFCNT_dec(MUTABLE_SV(hv));
	      }
	    }
	    cophh_free(CopHINTHASH_get(&PL_compiling));
	    CopHINTHASH_set(&PL_compiling, (COPHH*)ARG0_PTR);
	    *(I32*)&PL_hints = ARG1_I32;
	    if (PL_hints & HINT_LOCALIZE_HH) {
		SvREFCNT_dec(MUTABLE_SV(GvHV(PL_hintgv)));
		GvHV(PL_hintgv) = MUTABLE_HV(SSPOPPTR);
	    }
	    if (!GvHV(PL_hintgv)) {
		/* Need to add a new one manually, else rv2hv can
		   add one via GvHVn and it won't have the magic set.  */
		HV *const hv = newHV();
		hv_magic(hv, NULL, PERL_MAGIC_hints);
		GvHV(PL_hintgv) = hv;
	    }
	    assert(GvHV(PL_hintgv));
	    break;
	case SAVEt_COMPPAD:
	    PL_comppad = (PAD*)ARG0_PTR;
	    if (LIKELY(PL_comppad))
		PL_curpad = AvARRAY(PL_comppad);
	    else
		PL_curpad = NULL;
	    break;
	case SAVEt_PADSV_AND_MORTALIZE:
	    {
		SV **svp;
		assert (ARG1_PTR);
		svp = AvARRAY((PAD*)ARG1_PTR) + (PADOFFSET)arg0.any_uv;
		/* This mortalizing used to be done by POPLOOP() via itersave.
		   But as we have all the information here, we can do it here,
		   save even having to have itersave in the struct.  */
		sv_2mortal(*svp);
		*svp = ARG2_SV;
	    }
	    break;
	case SAVEt_SAVESWITCHSTACK:
	    {
		dSP;
		SWITCHSTACK(ARG0_AV, ARG1_AV);
		PL_curstackinfo->si_stack = ARG1_AV;
	    }
	    break;
	case SAVEt_SET_SVFLAGS:
            SvFLAGS(ARG2_SV) &= ~((U32)ARG1_I32);
            SvFLAGS(ARG2_SV) |= (U32)ARG0_I32;
	    break;

	    /* These are only saved in mathoms.c */
	case SAVEt_NSTAB:
	    (void)sv_clear(ARG0_SV);
	    break;
	case SAVEt_LONG:			/* long reference */
	    *(long*)ARG0_PTR = arg1.any_long;
	    break;
	case SAVEt_IV:				/* IV reference */
	    *(IV*)ARG0_PTR = arg1.any_iv;
	    break;

	case SAVEt_I16:				/* I16 reference */
	    *(I16*)ARG0_PTR = (I16)(uv >> 8);
	    break;
	case SAVEt_I8:				/* I8 reference */
	    *(I8*)ARG0_PTR = (I8)(uv >> 8);
	    break;
	case SAVEt_DESTRUCTOR:
	    (*arg1.any_dptr)(ARG0_PTR);
	    break;
	case SAVEt_COMPILE_WARNINGS:
	    if (!specialWARN(PL_compiling.cop_warnings))
		PerlMemShared_free(PL_compiling.cop_warnings);

	    PL_compiling.cop_warnings = (STRLEN*)ARG0_PTR;
	    break;
	case SAVEt_PARSER:
	    parser_free((yy_parser *) ARG0_PTR);
	    break;
	case SAVEt_READONLY_OFF:
	    SvREADONLY_off(ARG0_SV);
	    break;
	case SAVEt_GP_ALIASED_SV: {
	    /* The GP may have been abandoned, leaving the savestack with
	       the only remaining reference to it.  */
	    GP * const gp = (GP *)ARG0_PTR;
	    if (gp->gp_refcnt == 1) {
		GV * const gv = (GV *)sv_2mortal(newSV_type(SVt_PVGV));
		GvGP_set(gv,gp);
		gp_free(gv);
	    }
	    else {
		gp->gp_refcnt--;
		if (uv >> 8) gp->gp_flags |=  GPf_ALIASED_SV;
		else	     gp->gp_flags &= ~GPf_ALIASED_SV;
	    }
	    break;
	}
	default:
	    Perl_croak(aTHX_ "panic: leave_scope inconsistency %u", type);
	}
    }

    TAINT_set(was);
}

void
Perl_cx_dump(pTHX_ PERL_CONTEXT *cx)
{
    PERL_ARGS_ASSERT_CX_DUMP;

#ifdef DEBUGGING
    PerlIO_printf(Perl_debug_log, "CX %ld = %s\n", (long)(cx - cxstack), PL_block_type[CxTYPE(cx)]);
    if (CxTYPE(cx) != CXt_SUBST) {
	const char *gimme_text;
	PerlIO_printf(Perl_debug_log, "BLK_OLDSP = %ld\n", (long)cx->blk_oldsp);
	PerlIO_printf(Perl_debug_log, "BLK_OLDCOP = 0x%"UVxf"\n",
		      PTR2UV(cx->blk_oldcop));
	PerlIO_printf(Perl_debug_log, "BLK_OLDMARKSP = %ld\n", (long)cx->blk_oldmarksp);
	PerlIO_printf(Perl_debug_log, "BLK_OLDSCOPESP = %ld\n", (long)cx->blk_oldscopesp);
	PerlIO_printf(Perl_debug_log, "BLK_OLDPM = 0x%"UVxf"\n",
		      PTR2UV(cx->blk_oldpm));
	switch (cx->blk_gimme) {
	    case G_VOID:
		gimme_text = "VOID";
		break;
	    case G_SCALAR:
		gimme_text = "SCALAR";
		break;
	    case G_ARRAY:
		gimme_text = "LIST";
		break;
	    default:
		gimme_text = "UNKNOWN";
		break;
	}
	PerlIO_printf(Perl_debug_log, "BLK_GIMME = %s\n", gimme_text);
    }
    switch (CxTYPE(cx)) {
    case CXt_NULL:
    case CXt_BLOCK:
	break;
    case CXt_FORMAT:
	PerlIO_printf(Perl_debug_log, "BLK_FORMAT.CV = 0x%"UVxf"\n",
		PTR2UV(cx->blk_format.cv));
	PerlIO_printf(Perl_debug_log, "BLK_FORMAT.GV = 0x%"UVxf"\n",
		PTR2UV(cx->blk_format.gv));
	PerlIO_printf(Perl_debug_log, "BLK_FORMAT.DFOUTGV = 0x%"UVxf"\n",
		PTR2UV(cx->blk_format.dfoutgv));
	PerlIO_printf(Perl_debug_log, "BLK_FORMAT.HASARGS = %d\n",
		      (int)CxHASARGS(cx));
	PerlIO_printf(Perl_debug_log, "BLK_FORMAT.RETOP = 0x%"UVxf"\n",
		PTR2UV(cx->blk_format.retop));
	break;
    case CXt_SUB:
	PerlIO_printf(Perl_debug_log, "BLK_SUB.CV = 0x%"UVxf"\n",
		PTR2UV(cx->blk_sub.cv));
	PerlIO_printf(Perl_debug_log, "BLK_SUB.OLDDEPTH = %ld\n",
		(long)cx->blk_sub.olddepth);
	PerlIO_printf(Perl_debug_log, "BLK_SUB.HASARGS = %d\n",
		(int)CxHASARGS(cx));
	PerlIO_printf(Perl_debug_log, "BLK_SUB.LVAL = %d\n", (int)CxLVAL(cx));
	PerlIO_printf(Perl_debug_log, "BLK_SUB.RETOP = 0x%"UVxf"\n",
		PTR2UV(cx->blk_sub.retop));
	break;
    case CXt_EVAL:
	PerlIO_printf(Perl_debug_log, "BLK_EVAL.OLD_IN_EVAL = %ld\n",
		(long)CxOLD_IN_EVAL(cx));
	PerlIO_printf(Perl_debug_log, "BLK_EVAL.OLD_OP_TYPE = %s (%s)\n",
		PL_op_name[CxOLD_OP_TYPE(cx)],
		PL_op_desc[CxOLD_OP_TYPE(cx)]);
	if (cx->blk_eval.old_namesv)
	    PerlIO_printf(Perl_debug_log, "BLK_EVAL.OLD_NAME = %s\n",
			  SvPVX_const(cx->blk_eval.old_namesv));
	PerlIO_printf(Perl_debug_log, "BLK_EVAL.OLD_EVAL_ROOT = 0x%"UVxf"\n",
		PTR2UV(cx->blk_eval.old_eval_root));
	PerlIO_printf(Perl_debug_log, "BLK_EVAL.RETOP = 0x%"UVxf"\n",
		PTR2UV(cx->blk_eval.retop));
	break;

    case CXt_LOOP_LAZYIV:
    case CXt_LOOP_LAZYSV:
    case CXt_LOOP_FOR:
    case CXt_LOOP_PLAIN:
	PerlIO_printf(Perl_debug_log, "BLK_LOOP.LABEL = %s\n", CxLABEL(cx));
	PerlIO_printf(Perl_debug_log, "BLK_LOOP.RESETSP = %ld\n",
		(long)cx->blk_loop.resetsp);
	PerlIO_printf(Perl_debug_log, "BLK_LOOP.MY_OP = 0x%"UVxf"\n",
		PTR2UV(cx->blk_loop.my_op));
	/* XXX: not accurate for LAZYSV/IV */
	PerlIO_printf(Perl_debug_log, "BLK_LOOP.ITERARY = 0x%"UVxf"\n",
		PTR2UV(cx->blk_loop.state_u.ary.ary));
	PerlIO_printf(Perl_debug_log, "BLK_LOOP.ITERIX = %ld\n",
		(long)cx->blk_loop.state_u.ary.ix);
	PerlIO_printf(Perl_debug_log, "BLK_LOOP.ITERVAR = 0x%"UVxf"\n",
		PTR2UV(CxITERVAR(cx)));
	break;

    case CXt_SUBST:
	PerlIO_printf(Perl_debug_log, "SB_ITERS = %ld\n",
		(long)cx->sb_iters);
	PerlIO_printf(Perl_debug_log, "SB_MAXITERS = %ld\n",
		(long)cx->sb_maxiters);
	PerlIO_printf(Perl_debug_log, "SB_RFLAGS = %ld\n",
		(long)cx->sb_rflags);
	PerlIO_printf(Perl_debug_log, "SB_ONCE = %ld\n",
		(long)CxONCE(cx));
	PerlIO_printf(Perl_debug_log, "SB_ORIG = %s\n",
		cx->sb_orig);
	PerlIO_printf(Perl_debug_log, "SB_DSTR = 0x%"UVxf"\n",
		PTR2UV(cx->sb_dstr));
	PerlIO_printf(Perl_debug_log, "SB_TARG = 0x%"UVxf"\n",
		PTR2UV(cx->sb_targ));
	PerlIO_printf(Perl_debug_log, "SB_S = 0x%"UVxf"\n",
		PTR2UV(cx->sb_s));
	PerlIO_printf(Perl_debug_log, "SB_M = 0x%"UVxf"\n",
		PTR2UV(cx->sb_m));
	PerlIO_printf(Perl_debug_log, "SB_STREND = 0x%"UVxf"\n",
		PTR2UV(cx->sb_strend));
	PerlIO_printf(Perl_debug_log, "SB_RXRES = 0x%"UVxf"\n",
		PTR2UV(cx->sb_rxres));
	break;
    }
#else
    PERL_UNUSED_CONTEXT;
    PERL_UNUSED_ARG(cx);
#endif	/* DEBUGGING */
}

/*
 * Local variables:
 * c-indentation-style: bsd
 * c-basic-offset: 4
 * indent-tabs-mode: nil
 * End:
 *
 * ex: set ts=8 sts=4 sw=4 et:
 */