[perl5.git] / pad.h

/*    pad.h
 *
 *    Copyright (C) 2002, 2003, 2005, 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.
 *
 * This file defines the types and macros associated with the API for
 * manipulating scratchpads, which are used by perl to store lexical
 * variables, op targets and constants.
 */


/* a padlist is currently just an AV; but that might change,
 * so hide the type. Ditto a pad.  */

typedef AV PADLIST;
typedef AV PAD;


/* offsets within a pad */

#if PTRSIZE == 4
typedef U32TYPE PADOFFSET;
#else
#   if PTRSIZE == 8
typedef U64TYPE PADOFFSET;
#   endif
#endif
#define NOT_IN_PAD ((PADOFFSET) -1)
 

/* flags for the pad_new() function */

#define padnew_CLONE	1	/* this pad is for a cloned CV */
#define padnew_SAVE	2	/* save old globals */
#define padnew_SAVESUB	4	/* also save extra stuff for start of sub */

/* values for the pad_tidy() function */

typedef enum {
	padtidy_SUB,		/* tidy up a pad for a sub, */
	padtidy_SUBCLONE,	/* a cloned sub, */
	padtidy_FORMAT		/* or a format */
} padtidy_type;

/* ASSERT_CURPAD_LEGAL and ASSERT_CURPAD_ACTIVE respectively determine
 * whether PL_comppad and PL_curpad are consistent and whether they have
 * active values */

#ifdef DEBUGGING
#  define ASSERT_CURPAD_LEGAL(label) \
    if (PL_comppad ? (AvARRAY(PL_comppad) != PL_curpad) : (PL_curpad != 0))  \
	Perl_croak(aTHX_ "panic: illegal pad in %s: 0x%"UVxf"[0x%"UVxf"]",\
	    label, PTR2UV(PL_comppad), PTR2UV(PL_curpad));


#  define ASSERT_CURPAD_ACTIVE(label) \
    if (!PL_comppad || (AvARRAY(PL_comppad) != PL_curpad))		  \
	Perl_croak(aTHX_ "panic: invalid pad in %s: 0x%"UVxf"[0x%"UVxf"]",\
	    label, PTR2UV(PL_comppad), PTR2UV(PL_curpad));
#else
#  define ASSERT_CURPAD_LEGAL(label)
#  define ASSERT_CURPAD_ACTIVE(label)
#endif


/* Note: the following three macros are actually defined in scope.h, but
 * they are documented here for completeness, since they directly or
 * indirectly affect pads.

=for apidoc m|void|SAVEPADSV	|PADOFFSET po
Save a pad slot (used to restore after an iteration)

XXX DAPM it would make more sense to make the arg a PADOFFSET
=for apidoc m|void|SAVECLEARSV	|SV **svp
Clear the pointed to pad value on scope exit. (i.e. the runtime action of 'my')

=for apidoc m|void|SAVECOMPPAD
save PL_comppad and PL_curpad


=for apidoc m|SV *|PAD_SETSV	|PADOFFSET po|SV* sv
Set the slot at offset C<po> in the current pad to C<sv>

=for apidoc m|void|PAD_SV	|PADOFFSET po
Get the value at offset C<po> in the current pad

=for apidoc m|SV *|PAD_SVl	|PADOFFSET po
Lightweight and lvalue version of C<PAD_SV>.
Get or set the value at offset C<po> in the current pad.
Unlike C<PAD_SV>, does not print diagnostics with -DX.
For internal use only.

=for apidoc m|SV *|PAD_BASE_SV	|PADLIST padlist|PADOFFSET po
Get the value from slot C<po> in the base (DEPTH=1) pad of a padlist

=for apidoc m|void|PAD_SET_CUR	|PADLIST padlist|I32 n
Set the current pad to be pad C<n> in the padlist, saving
the previous current pad. NB currently this macro expands to a string too
long for some compilers, so it's best to replace it with

    SAVECOMPPAD();
    PAD_SET_CUR_NOSAVE(padlist,n);


=for apidoc m|void|PAD_SET_CUR_NOSAVE	|PADLIST padlist|I32 n
like PAD_SET_CUR, but without the save

=for apidoc m|void|PAD_SAVE_SETNULLPAD
Save the current pad then set it to null.

=for apidoc m|void|PAD_SAVE_LOCAL|PAD *opad|PAD *npad
Save the current pad to the local variable opad, then make the
current pad equal to npad

=for apidoc m|void|PAD_RESTORE_LOCAL|PAD *opad
Restore the old pad saved into the local variable opad by PAD_SAVE_LOCAL()

=cut
*/

#ifdef DEBUGGING
#  define PAD_SV(po)	   pad_sv(po)
#  define PAD_SETSV(po,sv) pad_setsv(po,sv)
#else
#  define PAD_SV(po)       (PL_curpad[po])
#  define PAD_SETSV(po,sv) PL_curpad[po] = (sv)
#endif

#define PAD_SVl(po)       (PL_curpad[po])

#define PAD_BASE_SV(padlist, po) \
	(AvARRAY(padlist)[1]) 	\
	    ? AvARRAY((AV*)(AvARRAY(padlist)[1]))[po] : NULL;
    

#define PAD_SET_CUR_NOSAVE(padlist,n) \
	PL_comppad = (PAD*) (AvARRAY(padlist)[n]);		\
	PL_curpad = AvARRAY(PL_comppad);			\
	DEBUG_Xv(PerlIO_printf(Perl_debug_log,			\
	      "Pad 0x%"UVxf"[0x%"UVxf"] set_cur    depth=%d\n",	\
	      PTR2UV(PL_comppad), PTR2UV(PL_curpad), (int)(n)));


#define PAD_SET_CUR(padlist,n) \
	SAVECOMPPAD();						\
	PAD_SET_CUR_NOSAVE(padlist,n);


#define PAD_SAVE_SETNULLPAD()	SAVECOMPPAD(); \
	PL_comppad = NULL; PL_curpad = NULL;	\
	DEBUG_Xv(PerlIO_printf(Perl_debug_log, "Pad set_null\n"));

#define PAD_SAVE_LOCAL(opad,npad) \
	opad = PL_comppad;					\
	PL_comppad = (npad);					\
	PL_curpad =  PL_comppad ? AvARRAY(PL_comppad) : NULL;	\
	DEBUG_Xv(PerlIO_printf(Perl_debug_log,			\
	      "Pad 0x%"UVxf"[0x%"UVxf"] save_local\n",		\
	      PTR2UV(PL_comppad), PTR2UV(PL_curpad)));

#define PAD_RESTORE_LOCAL(opad) \
	PL_comppad = opad;					\
	PL_curpad =  PL_comppad ? AvARRAY(PL_comppad) : NULL;	\
	DEBUG_Xv(PerlIO_printf(Perl_debug_log,			\
	      "Pad 0x%"UVxf"[0x%"UVxf"] restore_local\n",	\
	      PTR2UV(PL_comppad), PTR2UV(PL_curpad)));


/*
=for apidoc m|void|CX_CURPAD_SAVE|struct context
Save the current pad in the given context block structure.

=for apidoc m|SV *|CX_CURPAD_SV|struct context|PADOFFSET po
Access the SV at offset po in the saved current pad in the given
context block structure (can be used as an lvalue).

=cut
*/

#define CX_CURPAD_SAVE(block)  (block).oldcomppad = PL_comppad
#define CX_CURPAD_SV(block,po) (AvARRAY((AV*)((block).oldcomppad))[po])


/*
=for apidoc m|U32|PAD_COMPNAME_FLAGS|PADOFFSET po
Return the flags for the current compiling pad name
at offset C<po>. Assumes a valid slot entry.

=for apidoc m|char *|PAD_COMPNAME_PV|PADOFFSET po
Return the name of the current compiling pad name
at offset C<po>. Assumes a valid slot entry.

=for apidoc m|HV *|PAD_COMPNAME_TYPE|PADOFFSET po
Return the type (stash) of the current compiling pad name at offset
C<po>. Must be a valid name. Returns null if not typed.

=for apidoc m|HV *|PAD_COMPNAME_OURSTASH|PADOFFSET po
Return the stash associated with an C<our> variable.
Assumes the slot entry is a valid C<our> lexical.

=for apidoc m|STRLEN|PAD_COMPNAME_GEN|PADOFFSET po
The generation number of the name at offset C<po> in the current
compiling pad (lvalue). Note that C<SvCUR> is hijacked for this purpose.

=for apidoc m|STRLEN|PAD_COMPNAME_GEN_set|PADOFFSET po|int gen
Sets the generation number of the name at offset C<po> in the current
ling pad (lvalue) to C<gen>.  Note that C<SvCUR_set> is hijacked for this purpose.

=cut

*/

#define PAD_COMPNAME_FLAGS(po) SvFLAGS(*av_fetch(PL_comppad_name, (po), FALSE))
#define PAD_COMPNAME_FLAGS_isOUR(po) \
  ((PAD_COMPNAME_FLAGS(po) & (SVpad_NAME|SVpad_OUR)) == (SVpad_NAME|SVpad_OUR))
#define PAD_COMPNAME_PV(po) SvPV_nolen(*av_fetch(PL_comppad_name, (po), FALSE))

#define PAD_COMPNAME_TYPE(po) pad_compname_type(po)

#define PAD_COMPNAME_OURSTASH(po) \
    (OURSTASH(*av_fetch(PL_comppad_name, (po), FALSE)))

#define PAD_COMPNAME_GEN(po) SvCUR(AvARRAY(PL_comppad_name)[po])

#define PAD_COMPNAME_GEN_set(po, gen) SvCUR_set(AvARRAY(PL_comppad_name)[po], gen)


/*
=for apidoc m|void|PAD_DUP|PADLIST dstpad|PADLIST srcpad|CLONE_PARAMS* param
Clone a padlist.

=for apidoc m|void|PAD_CLONE_VARS|PerlInterpreter *proto_perl \
|CLONE_PARAMS* param
Clone the state variables associated with running and compiling pads.

=cut
*/


#define PAD_DUP(dstpad, srcpad, param)				\
    if ((srcpad) && !AvREAL(srcpad)) {				\
	/* XXX padlists are real, but pretend to be not */ 	\
	AvREAL_on(srcpad);					\
	(dstpad) = av_dup_inc((srcpad), param);			\
	AvREAL_off(srcpad);					\
	AvREAL_off(dstpad);					\
    }								\
    else							\
	(dstpad) = av_dup_inc((srcpad), param);			

/* NB - we set PL_comppad to null unless it points at a value that
 * has already been dup'ed, ie it points to part of an active padlist.
 * Otherwise PL_comppad ends up being a leaked scalar in code like
 * the following:
 *     threads->create(sub { threads->create(sub {...} ) } );
 * where the second thread dups the outer sub's comppad but not the
 * sub's CV or padlist. */

#define PAD_CLONE_VARS(proto_perl, param)				\
    PL_comppad = (AV *) ptr_table_fetch(PL_ptr_table, proto_perl->Icomppad); \
    PL_curpad = PL_comppad ?  AvARRAY(PL_comppad) : NULL;		\
    PL_comppad_name		= av_dup(proto_perl->Icomppad_name, param); \
    PL_comppad_name_fill	= proto_perl->Icomppad_name_fill;	\
    PL_comppad_name_floor	= proto_perl->Icomppad_name_floor;	\
    PL_min_intro_pending	= proto_perl->Imin_intro_pending;	\
    PL_max_intro_pending	= proto_perl->Imax_intro_pending;	\
    PL_padix			= proto_perl->Ipadix;			\
    PL_padix_floor		= proto_perl->Ipadix_floor;		\
    PL_pad_reset_pending	= proto_perl->Ipad_reset_pending;	\
    PL_cop_seqmax		= proto_perl->Icop_seqmax;
Commit	Line	Data
dd2155a4 DM	1	/* pad.h
dd2155a4 DM	2	*
45ca242c	3	* Copyright (C) 2002, 2003, 2005, by Larry Wall and others
dd2155a4 DM	4	*
	5	* You may distribute under the terms of either the GNU General Public
	6	* License or the Artistic License, as specified in the README file.
	7	*
	8	* This file defines the types and macros associated with the API for
	9	* manipulating scratchpads, which are used by perl to store lexical
	10	* variables, op targets and constants.
	11	*/
	12
	13
	14
	15
	16	/* a padlist is currently just an AV; but that might change,
	17	* so hide the type. Ditto a pad. */
	18
	19	typedef AV PADLIST;
f3548bdc	20	typedef AV PAD;
dd2155a4 DM	21
	22
	23	/* offsets within a pad */
	24
	25	#if PTRSIZE == 4
	26	typedef U32TYPE PADOFFSET;
	27	#else
	28	# if PTRSIZE == 8
	29	typedef U64TYPE PADOFFSET;
	30	# endif
	31	#endif
	32	#define NOT_IN_PAD ((PADOFFSET) -1)
	33
	34
	35	/* flags for the pad_new() function */
	36
c7c737cb DM	37	#define padnew_CLONE 1 /* this pad is for a cloned CV */
	38	#define padnew_SAVE 2 /* save old globals */
	39	#define padnew_SAVESUB 4 /* also save extra stuff for start of sub */
dd2155a4 DM	40
	41	/* values for the pad_tidy() function */
	42
	43	typedef enum {
	44	padtidy_SUB, /* tidy up a pad for a sub, */
	45	padtidy_SUBCLONE, /* a cloned sub, */
	46	padtidy_FORMAT /* or a format */
	47	} padtidy_type;
	48
f3548bdc DM	49	/* ASSERT_CURPAD_LEGAL and ASSERT_CURPAD_ACTIVE respectively determine
	50	* whether PL_comppad and PL_curpad are consistent and whether they have
	51	* active values */
dd2155a4	52
f3548bdc DM	53	#ifdef DEBUGGING
	54	# define ASSERT_CURPAD_LEGAL(label) \
	55	if (PL_comppad ? (AvARRAY(PL_comppad) != PL_curpad) : (PL_curpad != 0)) \
	56	Perl_croak(aTHX_ "panic: illegal pad in %s: 0x%"UVxf"[0x%"UVxf"]",\
	57	label, PTR2UV(PL_comppad), PTR2UV(PL_curpad));
	58
	59
	60	# define ASSERT_CURPAD_ACTIVE(label) \
	61	if (!PL_comppad \|\| (AvARRAY(PL_comppad) != PL_curpad)) \
	62	Perl_croak(aTHX_ "panic: invalid pad in %s: 0x%"UVxf"[0x%"UVxf"]",\
	63	label, PTR2UV(PL_comppad), PTR2UV(PL_curpad));
	64	#else
	65	# define ASSERT_CURPAD_LEGAL(label)
	66	# define ASSERT_CURPAD_ACTIVE(label)
	67	#endif
	68
	69
	70
	71	/* Note: the following three macros are actually defined in scope.h, but
dd2155a4 DM	72	* they are documented here for completeness, since they directly or
	73	* indirectly affect pads.
	74
	75	=for apidoc m\|void\|SAVEPADSV \|PADOFFSET po
	76	Save a pad slot (used to restore after an iteration)
	77
f3548bdc	78	XXX DAPM it would make more sense to make the arg a PADOFFSET
dd2155a4	79	=for apidoc m\|void\|SAVECLEARSV \|SV **svp
eeb8d49e	80	Clear the pointed to pad value on scope exit. (i.e. the runtime action of 'my')
dd2155a4 DM	81
	82	=for apidoc m\|void\|SAVECOMPPAD
	83	save PL_comppad and PL_curpad
	84
dd2155a4 DM	85
	86
	87
	88
	89	=for apidoc m\|SV \|PAD_SETSV \|PADOFFSET po\|SV sv
	90	Set the slot at offset C<po> in the current pad to C<sv>
	91
	92	=for apidoc m\|void\|PAD_SV \|PADOFFSET po
	93	Get the value at offset C<po> in the current pad
	94
	95	=for apidoc m\|SV *\|PAD_SVl \|PADOFFSET po
	96	Lightweight and lvalue version of C<PAD_SV>.
	97	Get or set the value at offset C<po> in the current pad.
	98	Unlike C<PAD_SV>, does not print diagnostics with -DX.
	99	For internal use only.
	100
	101	=for apidoc m\|SV *\|PAD_BASE_SV \|PADLIST padlist\|PADOFFSET po
	102	Get the value from slot C<po> in the base (DEPTH=1) pad of a padlist
	103
	104	=for apidoc m\|void\|PAD_SET_CUR \|PADLIST padlist\|I32 n
	105	Set the current pad to be pad C<n> in the padlist, saving
fd617465 DM	106	the previous current pad. NB currently this macro expands to a string too
	107	long for some compilers, so it's best to replace it with
	108
	109	SAVECOMPPAD();
	110	PAD_SET_CUR_NOSAVE(padlist,n);
	111
dd2155a4	112
4e380990 DM	113	=for apidoc m\|void\|PAD_SET_CUR_NOSAVE \|PADLIST padlist\|I32 n
	114	like PAD_SET_CUR, but without the save
	115
dd2155a4 DM	116	=for apidoc m\|void\|PAD_SAVE_SETNULLPAD
	117	Save the current pad then set it to null.
	118
f3548bdc DM	119	=for apidoc m\|void\|PAD_SAVE_LOCAL\|PAD opad\|PAD npad
	120	Save the current pad to the local variable opad, then make the
	121	current pad equal to npad
	122
	123	=for apidoc m\|void\|PAD_RESTORE_LOCAL\|PAD *opad
	124	Restore the old pad saved into the local variable opad by PAD_SAVE_LOCAL()
dd2155a4 DM	125
	126	=cut
	127	*/
	128
	129	#ifdef DEBUGGING
	130	# define PAD_SV(po) pad_sv(po)
	131	# define PAD_SETSV(po,sv) pad_setsv(po,sv)
	132	#else
	133	# define PAD_SV(po) (PL_curpad[po])
	134	# define PAD_SETSV(po,sv) PL_curpad[po] = (sv)
	135	#endif
	136
	137	#define PAD_SVl(po) (PL_curpad[po])
	138
	139	#define PAD_BASE_SV(padlist, po) \
	140	(AvARRAY(padlist)[1]) \
a0714e2c	141	? AvARRAY((AV*)(AvARRAY(padlist)[1]))[po] : NULL;
dd2155a4 DM	142
dd2155a4 DM	143
4e380990	144	#define PAD_SET_CUR_NOSAVE(padlist,n) \
f3548bdc DM	145	PL_comppad = (PAD*) (AvARRAY(padlist)[n]); \
	146	PL_curpad = AvARRAY(PL_comppad); \
	147	DEBUG_Xv(PerlIO_printf(Perl_debug_log, \
	148	"Pad 0x%"UVxf"[0x%"UVxf"] set_cur depth=%d\n", \
	149	PTR2UV(PL_comppad), PTR2UV(PL_curpad), (int)(n)));
	150
	151
4e380990 DM	152	#define PAD_SET_CUR(padlist,n) \
	153	SAVECOMPPAD(); \
	154	PAD_SET_CUR_NOSAVE(padlist,n);
	155
	156
f3548bdc	157	#define PAD_SAVE_SETNULLPAD() SAVECOMPPAD(); \
4608196e	158	PL_comppad = NULL; PL_curpad = NULL; \
f3548bdc DM	159	DEBUG_Xv(PerlIO_printf(Perl_debug_log, "Pad set_null\n"));
	160
	161	#define PAD_SAVE_LOCAL(opad,npad) \
	162	opad = PL_comppad; \
	163	PL_comppad = (npad); \
4608196e	164	PL_curpad = PL_comppad ? AvARRAY(PL_comppad) : NULL; \
f3548bdc DM	165	DEBUG_Xv(PerlIO_printf(Perl_debug_log, \
	166	"Pad 0x%"UVxf"[0x%"UVxf"] save_local\n", \
	167	PTR2UV(PL_comppad), PTR2UV(PL_curpad)));
	168
	169	#define PAD_RESTORE_LOCAL(opad) \
	170	PL_comppad = opad; \
4608196e	171	PL_curpad = PL_comppad ? AvARRAY(PL_comppad) : NULL; \
f3548bdc DM	172	DEBUG_Xv(PerlIO_printf(Perl_debug_log, \
	173	"Pad 0x%"UVxf"[0x%"UVxf"] restore_local\n", \
	174	PTR2UV(PL_comppad), PTR2UV(PL_curpad)));
dd2155a4 DM	175
	176
	177	/*
	178	=for apidoc m\|void\|CX_CURPAD_SAVE\|struct context
	179	Save the current pad in the given context block structure.
	180
f3548bdc	181	=for apidoc m\|SV *\|CX_CURPAD_SV\|struct context\|PADOFFSET po
dd2155a4 DM	182	Access the SV at offset po in the saved current pad in the given
	183	context block structure (can be used as an lvalue).
	184
	185	=cut
	186	*/
	187
f3548bdc DM	188	#define CX_CURPAD_SAVE(block) (block).oldcomppad = PL_comppad
f3548bdc DM	189	#define CX_CURPAD_SV(block,po) (AvARRAY((AV*)((block).oldcomppad))[po])
dd2155a4 DM	190
	191
	192	/*
	193	=for apidoc m\|U32\|PAD_COMPNAME_FLAGS\|PADOFFSET po
	194	Return the flags for the current compiling pad name
	195	at offset C<po>. Assumes a valid slot entry.
	196
	197	=for apidoc m\|char *\|PAD_COMPNAME_PV\|PADOFFSET po
	198	Return the name of the current compiling pad name
	199	at offset C<po>. Assumes a valid slot entry.
	200
	201	=for apidoc m\|HV *\|PAD_COMPNAME_TYPE\|PADOFFSET po
	202	Return the type (stash) of the current compiling pad name at offset
	203	C<po>. Must be a valid name. Returns null if not typed.
	204
	205	=for apidoc m\|HV *\|PAD_COMPNAME_OURSTASH\|PADOFFSET po
	206	Return the stash associated with an C<our> variable.
	207	Assumes the slot entry is a valid C<our> lexical.
	208
	209	=for apidoc m\|STRLEN\|PAD_COMPNAME_GEN\|PADOFFSET po
	210	The generation number of the name at offset C<po> in the current
	211	compiling pad (lvalue). Note that C<SvCUR> is hijacked for this purpose.
	212
b162af07 SP	213	=for apidoc m\|STRLEN\|PAD_COMPNAME_GEN_set\|PADOFFSET po\|int gen
	214	Sets the generation number of the name at offset C<po> in the current
	215	ling pad (lvalue) to C<gen>. Note that C<SvCUR_set> is hijacked for this purpose.
	216
dd2155a4	217	=cut
b162af07	218
dd2155a4 DM	219	*/
	220
	221	#define PAD_COMPNAME_FLAGS(po) SvFLAGS(*av_fetch(PL_comppad_name, (po), FALSE))
1e7f542f NC	222	#define PAD_COMPNAME_FLAGS_isOUR(po) \
1e7f542f NC	223	((PAD_COMPNAME_FLAGS(po) & (SVpad_NAME\|SVpad_OUR)) == (SVpad_NAME\|SVpad_OUR))
dd2155a4 DM	224	#define PAD_COMPNAME_PV(po) SvPV_nolen(*av_fetch(PL_comppad_name, (po), FALSE))
dd2155a4 DM	225
b21dc031	226	#define PAD_COMPNAME_TYPE(po) pad_compname_type(po)
dd2155a4 DM	227
dd2155a4 DM	228	#define PAD_COMPNAME_OURSTASH(po) \
035dab74	229	(OURSTASH(*av_fetch(PL_comppad_name, (po), FALSE)))
dd2155a4 DM	230
	231	#define PAD_COMPNAME_GEN(po) SvCUR(AvARRAY(PL_comppad_name)[po])
	232
b162af07	233	#define PAD_COMPNAME_GEN_set(po, gen) SvCUR_set(AvARRAY(PL_comppad_name)[po], gen)
dd2155a4 DM	234
	235
	236	/*
	237	=for apidoc m\|void\|PAD_DUP\|PADLIST dstpad\|PADLIST srcpad\|CLONE_PARAMS* param
	238	Clone a padlist.
	239
	240	=for apidoc m\|void\|PAD_CLONE_VARS\|PerlInterpreter *proto_perl \
	241	\|CLONE_PARAMS* param
	242	Clone the state variables associated with running and compiling pads.
	243
	244	=cut
	245	*/
	246
	247
	248	#define PAD_DUP(dstpad, srcpad, param) \
	249	if ((srcpad) && !AvREAL(srcpad)) { \
	250	/* XXX padlists are real, but pretend to be not */ \
	251	AvREAL_on(srcpad); \
	252	(dstpad) = av_dup_inc((srcpad), param); \
	253	AvREAL_off(srcpad); \
	254	AvREAL_off(dstpad); \
	255	} \
	256	else \
	257	(dstpad) = av_dup_inc((srcpad), param);
	258
c5ab0850 DM	259	/* NB - we set PL_comppad to null unless it points at a value that
	260	* has already been dup'ed, ie it points to part of an active padlist.
	261	* Otherwise PL_comppad ends up being a leaked scalar in code like
	262	* the following:
	263	* threads->create(sub { threads->create(sub {...} ) } );
	264	* where the second thread dups the outer sub's comppad but not the
	265	* sub's CV or padlist. */
f3548bdc	266
dd2155a4	267	#define PAD_CLONE_VARS(proto_perl, param) \
8f77bfdb	268	PL_comppad = (AV *) ptr_table_fetch(PL_ptr_table, proto_perl->Icomppad); \
4608196e	269	PL_curpad = PL_comppad ? AvARRAY(PL_comppad) : NULL; \
dd2155a4 DM	270	PL_comppad_name = av_dup(proto_perl->Icomppad_name, param); \
	271	PL_comppad_name_fill = proto_perl->Icomppad_name_fill; \
	272	PL_comppad_name_floor = proto_perl->Icomppad_name_floor; \
dd2155a4 DM	273	PL_min_intro_pending = proto_perl->Imin_intro_pending; \
	274	PL_max_intro_pending = proto_perl->Imax_intro_pending; \
	275	PL_padix = proto_perl->Ipadix; \
	276	PL_padix_floor = proto_perl->Ipadix_floor; \
	277	PL_pad_reset_pending = proto_perl->Ipad_reset_pending; \
	278	PL_cop_seqmax = proto_perl->Icop_seqmax;