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pad.c
2848 lines (2414 loc) · 92.2 KB
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pad.c
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/* pad.c
*
* Copyright (C) 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.
*/
/*
* 'Anyway: there was this Mr. Frodo left an orphan and stranded, as you
* might say, among those queer Bucklanders, being brought up anyhow in
* Brandy Hall. A regular warren, by all accounts. Old Master Gorbadoc
* never had fewer than a couple of hundred relations in the place.
* Mr. Bilbo never did a kinder deed than when he brought the lad back
* to live among decent folk.' --the Gaffer
*
* [p.23 of _The Lord of the Rings_, I/i: "A Long-Expected Party"]
*/
/*
=for apidoc_section $pad
=for apidoc Amx|PADLIST *|CvPADLIST|CV *cv
CV's can have CvPADLIST(cv) set to point to a PADLIST. This is the CV's
scratchpad, which stores lexical variables and opcode temporary and
per-thread values.
For these purposes "formats" are a kind-of CV; eval""s are too (except they're
not callable at will and are always thrown away after the eval"" is done
executing). Require'd files are simply evals without any outer lexical
scope.
XSUBs do not have a C<CvPADLIST>. C<dXSTARG> fetches values from C<PL_curpad>,
but that is really the callers pad (a slot of which is allocated by
every entersub). Do not get or set C<CvPADLIST> if a CV is an XSUB (as
determined by C<CvISXSUB()>), C<CvPADLIST> slot is reused for a different
internal purpose in XSUBs.
The PADLIST has a C array where pads are stored.
The 0th entry of the PADLIST is a PADNAMELIST
which represents the "names" or rather
the "static type information" for lexicals. The individual elements of a
PADNAMELIST are PADNAMEs. Future
refactorings might stop the PADNAMELIST from being stored in the PADLIST's
array, so don't rely on it. See L</PadlistNAMES>.
The CvDEPTH'th entry of a PADLIST is a PAD (an AV) which is the stack frame
at that depth of recursion into the CV. The 0th slot of a frame AV is an
AV which is C<@_>. Other entries are storage for variables and op targets.
Iterating over the PADNAMELIST iterates over all possible pad
items. Pad slots for targets (C<SVs_PADTMP>)
and GVs end up having &PL_padname_undef "names", while slots for constants
have C<&PL_padname_const> "names" (see C<L</pad_alloc>>). That
C<&PL_padname_undef>
and C<&PL_padname_const> are used is an implementation detail subject to
change. To test for them, use C<!PadnamePV(name)> and
S<C<PadnamePV(name) && !PadnameLEN(name)>>, respectively.
Only C<my>/C<our> variable slots get valid names.
The rest are op targets/GVs/constants which are statically allocated
or resolved at compile time. These don't have names by which they
can be looked up from Perl code at run time through eval"" the way
C<my>/C<our> variables can be. Since they can't be looked up by "name"
but only by their index allocated at compile time (which is usually
in C<< PL_op->op_targ >>), wasting a name SV for them doesn't make sense.
The pad names in the PADNAMELIST have their PV holding the name of
the variable. The C<COP_SEQ_RANGE_LOW> and C<_HIGH> fields form a range
(low+1..high inclusive) of cop_seq numbers for which the name is
valid. During compilation, these fields may hold the special value
PERL_PADSEQ_INTRO to indicate various stages:
COP_SEQ_RANGE_LOW _HIGH
----------------- -----
PERL_PADSEQ_INTRO 0 variable not yet introduced:
{ my ($x
valid-seq# PERL_PADSEQ_INTRO variable in scope:
{ my ($x);
valid-seq# valid-seq# compilation of scope complete:
{ my ($x); .... }
When a lexical var hasn't yet been introduced, it already exists from the
perspective of duplicate declarations, but not for variable lookups, e.g.
my ($x, $x); # '"my" variable $x masks earlier declaration'
my $x = $x; # equal to my $x = $::x;
For typed lexicals C<PadnameTYPE> points at the type stash. For C<our>
lexicals, C<PadnameOURSTASH> points at the stash of the associated global (so
that duplicate C<our> declarations in the same package can be detected).
C<PadnameGEN> is sometimes used to store the generation number during
compilation.
If C<PadnameOUTER> is set on the pad name, then that slot in the frame AV
is a REFCNT'ed reference to a lexical from "outside". Such entries
are sometimes referred to as 'fake'. In this case, the name does not
use 'low' and 'high' to store a cop_seq range, since it is in scope
throughout. Instead 'high' stores some flags containing info about
the real lexical (is it declared in an anon, and is it capable of being
instantiated multiple times?), and for fake ANONs, 'low' contains the index
within the parent's pad where the lexical's value is stored, to make
cloning quicker.
If the 'name' is C<&> the corresponding entry in the PAD
is a CV representing a possible closure.
Note that formats are treated as anon subs, and are cloned each time
write is called (if necessary).
The flag C<SVs_PADSTALE> is cleared on lexicals each time the C<my()> is executed,
and set on scope exit. This allows the
C<"Variable $x is not available"> warning
to be generated in evals, such as
{ my $x = 1; sub f { eval '$x'} } f();
For state vars, C<SVs_PADSTALE> is overloaded to mean 'not yet initialised',
but this internal state is stored in a separate pad entry.
=for apidoc Amnh||SVs_PADSTALE
=for apidoc AmnxU|PADNAMELIST *|PL_comppad_name
During compilation, this points to the array containing the names part
of the pad for the currently-compiling code.
=for apidoc AmnxU|PAD *|PL_comppad
During compilation, this points to the array containing the values
part of the pad for the currently-compiling code. (At runtime a CV may
have many such value arrays; at compile time just one is constructed.)
At runtime, this points to the array containing the currently-relevant
values for the pad for the currently-executing code.
=for apidoc AmnxU|SV **|PL_curpad
Points directly to the body of the L</PL_comppad> array.
(I.e., this is C<PadARRAY(PL_comppad)>.)
=cut
*/
#include "EXTERN.h"
#define PERL_IN_PAD_C
#include "perl.h"
#include "keywords.h"
#define COP_SEQ_RANGE_LOW_set(sv,val) \
STMT_START { (sv)->xpadn_low = (val); } STMT_END
#define COP_SEQ_RANGE_HIGH_set(sv,val) \
STMT_START { (sv)->xpadn_high = (val); } STMT_END
#define PARENT_PAD_INDEX_set COP_SEQ_RANGE_LOW_set
#define PARENT_FAKELEX_FLAGS_set COP_SEQ_RANGE_HIGH_set
#ifdef DEBUGGING
void
Perl_set_padlist(CV * cv, PADLIST *padlist){
PERL_ARGS_ASSERT_SET_PADLIST;
# if PTRSIZE == 8
assert((Size_t)padlist != UINT64_C(0xEFEFEFEFEFEFEFEF));
# elif PTRSIZE == 4
assert((Size_t)padlist != 0xEFEFEFEF);
# else
# error unknown pointer size
# endif
assert(!CvISXSUB(cv));
((XPVCV*)MUTABLE_PTR(SvANY(cv)))->xcv_padlist_u.xcv_padlist = padlist;
}
#endif
/*
=for apidoc pad_new
Create a new padlist, updating the global variables for the
currently-compiling padlist to point to the new padlist. The following
flags can be OR'ed together:
padnew_CLONE this pad is for a cloned CV
padnew_SAVE save old globals on the save stack
padnew_SAVESUB also save extra stuff for start of sub
=cut
*/
PADLIST *
Perl_pad_new(pTHX_ int flags)
{
PADLIST *padlist;
PADNAMELIST *padname;
PAD *pad;
PAD **ary;
ASSERT_CURPAD_LEGAL("pad_new");
/* save existing state, ... */
if (flags & padnew_SAVE) {
SAVECOMPPAD();
if (! (flags & padnew_CLONE)) {
SAVESPTR(PL_comppad_name);
save_strlen((STRLEN *)&PL_padix);
save_strlen((STRLEN *)&PL_constpadix);
save_strlen((STRLEN *)&PL_comppad_name_fill);
save_strlen((STRLEN *)&PL_min_intro_pending);
save_strlen((STRLEN *)&PL_max_intro_pending);
SAVEBOOL(PL_cv_has_eval);
if (flags & padnew_SAVESUB) {
SAVEBOOL(PL_pad_reset_pending);
}
}
}
/* ... create new pad ... */
Newxz(padlist, 1, PADLIST);
pad = newAV();
Newxz(AvALLOC(pad), 4, SV *); /* Originally sized to
match av_extend default */
AvARRAY(pad) = AvALLOC(pad);
AvMAX(pad) = 3;
AvFILLp(pad) = 0; /* @_ or NULL, set below. */
if (flags & padnew_CLONE) {
AV * const a0 = newAV(); /* will be @_ */
AvARRAY(pad)[0] = MUTABLE_SV(a0);
AvREIFY_only(a0);
PadnamelistREFCNT(padname = PL_comppad_name)++;
}
else {
padlist->xpadl_id = PL_padlist_generation++;
/* Set implicitly through use of Newxz above
AvARRAY(pad)[0] = NULL;
*/
padname = newPADNAMELIST(0);
padnamelist_store(padname, 0, &PL_padname_undef);
}
/* Most subroutines never recurse, hence only need 2 entries in the padlist
array - names, and depth=1. The default for av_store() is to allocate
0..3, and even an explicit call to av_extend() with <3 will be rounded
up, so we inline the allocation of the array here. */
Newx(ary, 2, PAD *);
PadlistMAX(padlist) = 1;
PadlistARRAY(padlist) = ary;
ary[0] = (PAD *)padname;
ary[1] = pad;
/* ... then update state variables */
PL_comppad = pad;
PL_curpad = AvARRAY(pad);
if (! (flags & padnew_CLONE)) {
PL_comppad_name = padname;
PL_comppad_name_fill = 0;
PL_min_intro_pending = 0;
PL_padix = 0;
PL_constpadix = 0;
PL_cv_has_eval = 0;
}
DEBUG_X(PerlIO_printf(Perl_debug_log,
"Pad 0x%" UVxf "[0x%" UVxf "] new: compcv=0x%" UVxf
" name=0x%" UVxf " flags=0x%" UVxf "\n",
PTR2UV(PL_comppad), PTR2UV(PL_curpad), PTR2UV(PL_compcv),
PTR2UV(padname), (UV)flags
)
);
return (PADLIST*)padlist;
}
/*
=for apidoc_section $embedding
=for apidoc cv_undef
Clear out all the active components of a CV. This can happen either
by an explicit C<undef &foo>, or by the reference count going to zero.
In the former case, we keep the C<CvOUTSIDE> pointer, so that any anonymous
children can still follow the full lexical scope chain.
=cut
*/
void
Perl_cv_undef(pTHX_ CV *cv)
{
PERL_ARGS_ASSERT_CV_UNDEF;
cv_undef_flags(cv, 0);
}
void
Perl_cv_undef_flags(pTHX_ CV *cv, U32 flags)
{
CV cvbody;/*CV body will never be realloced inside this func,
so dont read it more than once, use fake CV so existing macros
will work, the indirection and CV head struct optimized away*/
SvANY(&cvbody) = SvANY(cv);
PERL_ARGS_ASSERT_CV_UNDEF_FLAGS;
DEBUG_X(PerlIO_printf(Perl_debug_log,
"CV undef: cv=0x%" UVxf " comppad=0x%" UVxf "\n",
PTR2UV(cv), PTR2UV(PL_comppad))
);
if (CvFILE(&cvbody)) {
char * file = CvFILE(&cvbody);
CvFILE(&cvbody) = NULL;
if(CvDYNFILE(&cvbody))
Safefree(file);
}
/* CvSLABBED_off(&cvbody); *//* turned off below */
/* release the sub's body */
if (!CvISXSUB(&cvbody)) {
if(CvROOT(&cvbody)) {
assert(SvTYPE(cv) == SVt_PVCV || SvTYPE(cv) == SVt_PVFM); /*unsafe is safe */
if (CvDEPTHunsafe(&cvbody)) {
assert(SvTYPE(cv) == SVt_PVCV);
Perl_croak_nocontext("Can't undef active subroutine");
}
ENTER;
PAD_SAVE_SETNULLPAD();
if (CvSLABBED(&cvbody)) OpslabREFCNT_dec_padok(OpSLAB(CvROOT(&cvbody)));
op_free(CvROOT(&cvbody));
CvROOT(&cvbody) = NULL;
CvSTART(&cvbody) = NULL;
LEAVE;
}
else if (CvSLABBED(&cvbody)) {
if( CvSTART(&cvbody)) {
ENTER;
PAD_SAVE_SETNULLPAD();
/* discard any leaked ops */
if (PL_parser)
parser_free_nexttoke_ops(PL_parser, (OPSLAB *)CvSTART(&cvbody));
opslab_force_free((OPSLAB *)CvSTART(&cvbody));
CvSTART(&cvbody) = NULL;
LEAVE;
}
#ifdef DEBUGGING
else Perl_warn(aTHX_ "Slab leaked from cv %p", (void*)cv);
#endif
}
}
else { /* dont bother checking if CvXSUB(cv) is true, less branching */
CvXSUB(&cvbody) = NULL;
}
SvPOK_off(MUTABLE_SV(cv)); /* forget prototype */
sv_unmagic((SV *)cv, PERL_MAGIC_checkcall);
if (!(flags & CV_UNDEF_KEEP_NAME)) {
if (CvNAMED(&cvbody)) {
CvNAME_HEK_set(&cvbody, NULL);
CvNAMED_off(&cvbody);
}
else CvGV_set(cv, NULL);
}
/* This statement and the subsequence if block was pad_undef(). */
pad_peg("pad_undef");
if (!CvISXSUB(&cvbody) && CvPADLIST(&cvbody)) {
PADOFFSET ix;
const PADLIST *padlist = CvPADLIST(&cvbody);
/* Free the padlist associated with a CV.
If parts of it happen to be current, we null the relevant PL_*pad*
global vars so that we don't have any dangling references left.
We also repoint the CvOUTSIDE of any about-to-be-orphaned inner
subs to the outer of this cv. */
DEBUG_X(PerlIO_printf(Perl_debug_log,
"Pad undef: cv=0x%" UVxf " padlist=0x%" UVxf " comppad=0x%" UVxf "\n",
PTR2UV(cv), PTR2UV(padlist), PTR2UV(PL_comppad))
);
/* detach any '&' anon children in the pad; if afterwards they
* are still live, fix up their CvOUTSIDEs to point to our outside,
* bypassing us. */
if (PL_phase != PERL_PHASE_DESTRUCT) { /* don't bother during global destruction */
CV * const outercv = CvOUTSIDE(&cvbody);
const U32 seq = CvOUTSIDE_SEQ(&cvbody);
PADNAMELIST * const comppad_name = PadlistNAMES(padlist);
PADNAME ** const namepad = PadnamelistARRAY(comppad_name);
PAD * const comppad = PadlistARRAY(padlist)[1];
SV ** const curpad = AvARRAY(comppad);
for (ix = PadnamelistMAX(comppad_name); ix > 0; ix--) {
PADNAME * const name = namepad[ix];
if (name && PadnamePV(name) && *PadnamePV(name) == '&')
{
CV * const innercv = MUTABLE_CV(curpad[ix]);
U32 inner_rc;
assert(innercv);
assert(SvTYPE(innercv) != SVt_PVFM);
inner_rc = SvREFCNT(innercv);
assert(inner_rc);
if (SvREFCNT(comppad) < 2) { /* allow for /(?{ sub{} })/ */
curpad[ix] = NULL;
SvREFCNT_dec_NN(innercv);
inner_rc--;
}
/* in use, not just a prototype */
if (inner_rc && SvTYPE(innercv) == SVt_PVCV
&& (CvOUTSIDE(innercv) == cv))
{
assert(CvWEAKOUTSIDE(innercv));
/* don't relink to grandfather if he's being freed */
if (outercv && SvREFCNT(outercv)) {
CvWEAKOUTSIDE_off(innercv);
CvOUTSIDE(innercv) = outercv;
CvOUTSIDE_SEQ(innercv) = seq;
SvREFCNT_inc_simple_void_NN(outercv);
}
else {
CvOUTSIDE(innercv) = NULL;
}
}
}
}
}
ix = PadlistMAX(padlist);
while (ix > 0) {
PAD * const sv = PadlistARRAY(padlist)[ix--];
if (sv) {
if (sv == PL_comppad) {
PL_comppad = NULL;
PL_curpad = NULL;
}
SvREFCNT_dec_NN(sv);
}
}
{
PADNAMELIST * const names = PadlistNAMES(padlist);
if (names == PL_comppad_name && PadnamelistREFCNT(names) == 1)
PL_comppad_name = NULL;
PadnamelistREFCNT_dec(names);
}
if (PadlistARRAY(padlist)) Safefree(PadlistARRAY(padlist));
Safefree(padlist);
CvPADLIST_set(&cvbody, NULL);
}
else if (CvISXSUB(&cvbody))
CvHSCXT(&cvbody) = NULL;
/* else is (!CvISXSUB(&cvbody) && !CvPADLIST(&cvbody)) {do nothing;} */
/* remove CvOUTSIDE unless this is an undef rather than a free */
if (!SvREFCNT(cv)) {
CV * outside = CvOUTSIDE(&cvbody);
if(outside) {
CvOUTSIDE(&cvbody) = NULL;
if (!CvWEAKOUTSIDE(&cvbody))
SvREFCNT_dec_NN(outside);
}
}
if (CvCONST(&cvbody)) {
SvREFCNT_dec(MUTABLE_SV(CvXSUBANY(&cvbody).any_ptr));
/* CvCONST_off(cv); *//* turned off below */
}
/* delete all flags except WEAKOUTSIDE and CVGV_RC, which indicate the
* ref status of CvOUTSIDE and CvGV, and ANON, NAMED and
* LEXICAL, which are used to determine the sub's name. */
CvFLAGS(&cvbody) &= (CVf_WEAKOUTSIDE|CVf_CVGV_RC|CVf_ANON|CVf_LEXICAL
|CVf_NAMED);
}
/*
=for apidoc cv_forget_slab
When a CV has a reference count on its slab (C<CvSLABBED>), it is responsible
for making sure it is freed. (Hence, no two CVs should ever have a
reference count on the same slab.) The CV only needs to reference the slab
during compilation. Once it is compiled and C<CvROOT> attached, it has
finished its job, so it can forget the slab.
=cut
*/
void
Perl_cv_forget_slab(pTHX_ CV *cv)
{
bool slabbed;
OPSLAB *slab = NULL;
if (!cv)
return;
slabbed = cBOOL(CvSLABBED(cv));
if (!slabbed) return;
CvSLABBED_off(cv);
if (CvROOT(cv)) slab = OpSLAB(CvROOT(cv));
else if (CvSTART(cv)) slab = (OPSLAB *)CvSTART(cv);
#ifdef DEBUGGING
else if (slabbed) Perl_warn(aTHX_ "Slab leaked from cv %p", (void*)cv);
#endif
if (slab) {
#ifdef PERL_DEBUG_READONLY_OPS
const size_t refcnt = slab->opslab_refcnt;
#endif
OpslabREFCNT_dec(slab);
#ifdef PERL_DEBUG_READONLY_OPS
if (refcnt > 1) Slab_to_ro(slab);
#endif
}
}
/*
=for apidoc pad_alloc_name
Allocates a place in the currently-compiling
pad (via L<perlapi/pad_alloc>) and
then stores a name for that entry. C<name> is adopted and
becomes the name entry; it must already contain the name
string. C<typestash> and C<ourstash> and the C<padadd_STATE>
flag get added to C<name>. None of the other
processing of L<perlapi/pad_add_name_pvn>
is done. Returns the offset of the allocated pad slot.
=cut
*/
static PADOFFSET
S_pad_alloc_name(pTHX_ PADNAME *name, U32 flags, HV *typestash,
HV *ourstash)
{
const PADOFFSET offset = pad_alloc(OP_PADSV, SVs_PADMY);
PERL_ARGS_ASSERT_PAD_ALLOC_NAME;
ASSERT_CURPAD_ACTIVE("pad_alloc_name");
if (typestash) {
SvPAD_TYPED_on(name);
PadnameTYPE(name) =
MUTABLE_HV(SvREFCNT_inc_simple_NN(MUTABLE_SV(typestash)));
}
if (ourstash) {
SvPAD_OUR_on(name);
SvOURSTASH_set(name, ourstash);
SvREFCNT_inc_simple_void_NN(ourstash);
}
else if (flags & padadd_STATE) {
SvPAD_STATE_on(name);
}
padnamelist_store(PL_comppad_name, offset, name);
if (PadnameLEN(name) > 1)
PadnamelistMAXNAMED(PL_comppad_name) = offset;
return offset;
}
/*
=for apidoc pad_add_name_pvn
Allocates a place in the currently-compiling pad for a named lexical
variable. Stores the name and other metadata in the name part of the
pad, and makes preparations to manage the variable's lexical scoping.
Returns the offset of the allocated pad slot.
C<namepv>/C<namelen> specify the variable's name, including leading sigil.
If C<typestash> is non-null, the name is for a typed lexical, and this
identifies the type. If C<ourstash> is non-null, it's a lexical reference
to a package variable, and this identifies the package. The following
flags can be OR'ed together:
padadd_OUR redundantly specifies if it's a package var
padadd_STATE variable will retain value persistently
padadd_NO_DUP_CHECK skip check for lexical shadowing
=cut
*/
PADOFFSET
Perl_pad_add_name_pvn(pTHX_ const char *namepv, STRLEN namelen,
U32 flags, HV *typestash, HV *ourstash)
{
PADOFFSET offset;
PADNAME *name;
PERL_ARGS_ASSERT_PAD_ADD_NAME_PVN;
if (flags & ~(padadd_OUR|padadd_STATE|padadd_NO_DUP_CHECK))
Perl_croak(aTHX_ "panic: pad_add_name_pvn illegal flag bits 0x%" UVxf,
(UV)flags);
name = newPADNAMEpvn(namepv, namelen);
if ((flags & padadd_NO_DUP_CHECK) == 0) {
ENTER;
SAVEFREEPADNAME(name); /* in case of fatal warnings */
/* check for duplicate declaration */
pad_check_dup(name, flags & padadd_OUR, ourstash);
PadnameREFCNT(name)++;
LEAVE;
}
offset = pad_alloc_name(name, flags, typestash, ourstash);
/* not yet introduced */
COP_SEQ_RANGE_LOW_set(name, PERL_PADSEQ_INTRO);
COP_SEQ_RANGE_HIGH_set(name, 0);
if (!PL_min_intro_pending)
PL_min_intro_pending = offset;
PL_max_intro_pending = offset;
/* if it's not a simple scalar, replace with an AV or HV */
assert(SvTYPE(PL_curpad[offset]) == SVt_NULL);
assert(SvREFCNT(PL_curpad[offset]) == 1);
if (namelen != 0 && *namepv == '@')
sv_upgrade(PL_curpad[offset], SVt_PVAV);
else if (namelen != 0 && *namepv == '%')
sv_upgrade(PL_curpad[offset], SVt_PVHV);
else if (namelen != 0 && *namepv == '&')
sv_upgrade(PL_curpad[offset], SVt_PVCV);
assert(SvPADMY(PL_curpad[offset]));
DEBUG_Xv(PerlIO_printf(Perl_debug_log,
"Pad addname: %ld \"%s\" new lex=0x%" UVxf "\n",
(long)offset, PadnamePV(name),
PTR2UV(PL_curpad[offset])));
return offset;
}
/*
=for apidoc pad_add_name_pv
Exactly like L</pad_add_name_pvn>, but takes a nul-terminated string
instead of a string/length pair.
=cut
*/
PADOFFSET
Perl_pad_add_name_pv(pTHX_ const char *name,
const U32 flags, HV *typestash, HV *ourstash)
{
PERL_ARGS_ASSERT_PAD_ADD_NAME_PV;
return pad_add_name_pvn(name, strlen(name), flags, typestash, ourstash);
}
/*
=for apidoc pad_add_name_sv
Exactly like L</pad_add_name_pvn>, but takes the name string in the form
of an SV instead of a string/length pair.
=cut
*/
PADOFFSET
Perl_pad_add_name_sv(pTHX_ SV *name, U32 flags, HV *typestash, HV *ourstash)
{
char *namepv;
STRLEN namelen;
PERL_ARGS_ASSERT_PAD_ADD_NAME_SV;
namepv = SvPVutf8(name, namelen);
return pad_add_name_pvn(namepv, namelen, flags, typestash, ourstash);
}
/*
=for apidoc pad_alloc
Allocates a place in the currently-compiling pad,
returning the offset of the allocated pad slot.
No name is initially attached to the pad slot.
C<tmptype> is a set of flags indicating the kind of pad entry required,
which will be set in the value SV for the allocated pad entry:
SVs_PADMY named lexical variable ("my", "our", "state")
SVs_PADTMP unnamed temporary store
SVf_READONLY constant shared between recursion levels
C<SVf_READONLY> has been supported here only since perl 5.20. To work with
earlier versions as well, use C<SVf_READONLY|SVs_PADTMP>. C<SVf_READONLY>
does not cause the SV in the pad slot to be marked read-only, but simply
tells C<pad_alloc> that it I<will> be made read-only (by the caller), or at
least should be treated as such.
C<optype> should be an opcode indicating the type of operation that the
pad entry is to support. This doesn't affect operational semantics,
but is used for debugging.
=cut
*/
PADOFFSET
Perl_pad_alloc(pTHX_ I32 optype, U32 tmptype)
{
SV *sv;
PADOFFSET retval;
PERL_UNUSED_ARG(optype);
ASSERT_CURPAD_ACTIVE("pad_alloc");
if (AvARRAY(PL_comppad) != PL_curpad)
Perl_croak(aTHX_ "panic: pad_alloc, %p!=%p",
AvARRAY(PL_comppad), PL_curpad);
if (PL_pad_reset_pending)
pad_reset();
if (tmptype == SVs_PADMY) { /* Not & because this ‘flag’ is 0. */
/* For a my, simply push a null SV onto the end of PL_comppad. */
sv = *av_store_simple(PL_comppad, AvFILLp(PL_comppad) + 1, newSV(0));
retval = (PADOFFSET)AvFILLp(PL_comppad);
}
else {
/* For a tmp, scan the pad from PL_padix upwards
* for a slot which has no name and no active value.
* For a constant, likewise, but use PL_constpadix.
*/
PADNAME * const * const names = PadnamelistARRAY(PL_comppad_name);
const SSize_t names_fill = PadnamelistMAX(PL_comppad_name);
const bool konst = cBOOL(tmptype & SVf_READONLY);
retval = konst ? PL_constpadix : PL_padix;
for (;;) {
/*
* Entries that close over unavailable variables
* in outer subs contain values not marked PADMY.
* Thus we must skip, not just pad values that are
* marked as current pad values, but also those with names.
* If pad_reset is enabled, ‘current’ means different
* things depending on whether we are allocating a con-
* stant or a target. For a target, things marked PADTMP
* can be reused; not so for constants.
*/
PADNAME *pn;
if (++retval <= names_fill &&
(pn = names[retval]) && PadnamePV(pn))
continue;
sv = *av_fetch_simple(PL_comppad, retval, TRUE);
if (!(SvFLAGS(sv) &
#ifdef USE_PAD_RESET
(konst ? SVs_PADTMP : 0)
#else
SVs_PADTMP
#endif
))
break;
}
if (konst) {
padnamelist_store(PL_comppad_name, retval, &PL_padname_const);
tmptype &= ~SVf_READONLY;
tmptype |= SVs_PADTMP;
}
*(konst ? &PL_constpadix : &PL_padix) = retval;
}
SvFLAGS(sv) |= tmptype;
PL_curpad = AvARRAY(PL_comppad);
DEBUG_X(PerlIO_printf(Perl_debug_log,
"Pad 0x%" UVxf "[0x%" UVxf "] alloc: %ld for %s\n",
PTR2UV(PL_comppad), PTR2UV(PL_curpad), (long) retval,
PL_op_name[optype]));
#ifdef DEBUG_LEAKING_SCALARS
sv->sv_debug_optype = optype;
sv->sv_debug_inpad = 1;
#endif
return retval;
}
/*
=for apidoc pad_add_anon
Allocates a place in the currently-compiling pad (via L</pad_alloc>)
for an anonymous function that is lexically scoped inside the
currently-compiling function.
The function C<func> is linked into the pad, and its C<CvOUTSIDE> link
to the outer scope is weakened to avoid a reference loop.
One reference count is stolen, so you may need to do C<SvREFCNT_inc(func)>.
C<optype> should be an opcode indicating the type of operation that the
pad entry is to support. This doesn't affect operational semantics,
but is used for debugging.
=cut
*/
PADOFFSET
Perl_pad_add_anon(pTHX_ CV* func, I32 optype)
{
PADOFFSET ix;
PADNAME * const name = newPADNAMEpvn("&", 1);
PERL_ARGS_ASSERT_PAD_ADD_ANON;
assert (SvTYPE(func) == SVt_PVCV);
pad_peg("add_anon");
/* These two aren't used; just make sure they're not equal to
* PERL_PADSEQ_INTRO. They should be 0 by default. */
assert(COP_SEQ_RANGE_LOW (name) != PERL_PADSEQ_INTRO);
assert(COP_SEQ_RANGE_HIGH(name) != PERL_PADSEQ_INTRO);
ix = pad_alloc(optype, SVs_PADMY);
padnamelist_store(PL_comppad_name, ix, name);
av_store(PL_comppad, ix, (SV*)func);
/* to avoid ref loops, we never have parent + child referencing each
* other simultaneously */
if (CvOUTSIDE(func)) {
assert(!CvWEAKOUTSIDE(func));
CvWEAKOUTSIDE_on(func);
SvREFCNT_dec_NN(CvOUTSIDE(func));
}
return ix;
}
void
Perl_pad_add_weakref(pTHX_ CV* func)
{
const PADOFFSET ix = pad_alloc(OP_NULL, SVs_PADMY);
PADNAME * const name = newPADNAMEpvn("&", 1);
SV * const rv = newRV_inc((SV *)func);
PERL_ARGS_ASSERT_PAD_ADD_WEAKREF;
/* These two aren't used; just make sure they're not equal to
* PERL_PADSEQ_INTRO. They should be 0 by default. */
assert(COP_SEQ_RANGE_LOW (name) != PERL_PADSEQ_INTRO);
assert(COP_SEQ_RANGE_HIGH(name) != PERL_PADSEQ_INTRO);
padnamelist_store(PL_comppad_name, ix, name);
sv_rvweaken(rv);
av_store(PL_comppad, ix, rv);
}
/*
=for apidoc pad_check_dup
Check for duplicate declarations: report any of:
* a 'my' in the current scope with the same name;
* an 'our' (anywhere in the pad) with the same name and the
same stash as 'ourstash'
C<is_our> indicates that the name to check is an C<"our"> declaration.
=cut
*/
STATIC void
S_pad_check_dup(pTHX_ PADNAME *name, U32 flags, const HV *ourstash)
{
PADNAME **svp;
PADOFFSET top, off;
const U32 is_our = flags & padadd_OUR;
PERL_ARGS_ASSERT_PAD_CHECK_DUP;
ASSERT_CURPAD_ACTIVE("pad_check_dup");
assert((flags & ~padadd_OUR) == 0);
if (PadnamelistMAX(PL_comppad_name) < 0 || !ckWARN(WARN_SHADOW))
return; /* nothing to check */
svp = PadnamelistARRAY(PL_comppad_name);
top = PadnamelistMAX(PL_comppad_name);
/* check the current scope */
for (off = top; off > PL_comppad_name_floor; off--) {
PADNAME * const sv = svp[off];
if (sv
&& PadnameLEN(sv) == PadnameLEN(name)
&& !PadnameOUTER(sv)
&& ( COP_SEQ_RANGE_LOW(sv) == PERL_PADSEQ_INTRO
|| COP_SEQ_RANGE_HIGH(sv) == PERL_PADSEQ_INTRO)
&& memEQ(PadnamePV(sv), PadnamePV(name), PadnameLEN(name)))
{
if (is_our && (SvPAD_OUR(sv)))
break; /* "our" masking "our" */
/* diag_listed_as: "%s" variable %s masks earlier declaration in same %s */
Perl_warner(aTHX_ packWARN(WARN_SHADOW),
"\"%s\" %s %" PNf " masks earlier declaration in same %s",
( is_our ? "our" :
PL_parser->in_my == KEY_my ? "my" :
PL_parser->in_my == KEY_sigvar ? "my" :
"state" ),
*PadnamePV(sv) == '&' ? "subroutine" : "variable",
PNfARG(sv),
(COP_SEQ_RANGE_HIGH(sv) == PERL_PADSEQ_INTRO
? "scope" : "statement"));
--off;
break;
}
}
/* check the rest of the pad */
if (is_our) {
while (off > 0) {
PADNAME * const sv = svp[off];
if (sv
&& PadnameLEN(sv) == PadnameLEN(name)
&& !PadnameOUTER(sv)
&& ( COP_SEQ_RANGE_LOW(sv) == PERL_PADSEQ_INTRO
|| COP_SEQ_RANGE_HIGH(sv) == PERL_PADSEQ_INTRO)
&& SvOURSTASH(sv) == ourstash
&& memEQ(PadnamePV(sv), PadnamePV(name), PadnameLEN(name)))
{
Perl_warner(aTHX_ packWARN(WARN_SHADOW),
"\"our\" variable %" PNf " redeclared", PNfARG(sv));
if (off <= PL_comppad_name_floor)
Perl_warner(aTHX_ packWARN(WARN_SHADOW),
"\t(Did you mean \"local\" instead of \"our\"?)\n");
break;
}
--off;
}
}
}
/*
=for apidoc pad_findmy_pvn
Given the name of a lexical variable, find its position in the
currently-compiling pad.
C<namepv>/C<namelen> specify the variable's name, including leading sigil.
C<flags> is reserved and must be zero.
If it is not in the current pad but appears in the pad of any lexically
enclosing scope, then a pseudo-entry for it is added in the current pad.
Returns the offset in the current pad,
or C<NOT_IN_PAD> if no such lexical is in scope.
=cut
*/
PADOFFSET
Perl_pad_findmy_pvn(pTHX_ const char *namepv, STRLEN namelen, U32 flags)
{
PADNAME *out_pn;
int out_flags;
PADOFFSET offset;
const PADNAMELIST *namelist;
PADNAME **name_p;
PERL_ARGS_ASSERT_PAD_FINDMY_PVN;
pad_peg("pad_findmy_pvn");
if (flags)
Perl_croak(aTHX_ "panic: pad_findmy_pvn illegal flag bits 0x%" UVxf,
(UV)flags);
/* compilation errors can zero PL_compcv */
if (!PL_compcv)
return NOT_IN_PAD;
offset = pad_findlex(namepv, namelen, flags,
PL_compcv, PL_cop_seqmax, 1, NULL, &out_pn, &out_flags);
if (offset != NOT_IN_PAD)
return offset;
/* Skip the ‘our’ hack for subroutines, as the warning does not apply.
*/
if (*namepv == '&') return NOT_IN_PAD;
/* look for an our that's being introduced; this allows
* our $foo = 0 unless defined $foo;
* to not give a warning. (Yes, this is a hack) */
namelist = PadlistNAMES(CvPADLIST(PL_compcv));
name_p = PadnamelistARRAY(namelist);
for (offset = PadnamelistMAXNAMED(namelist); offset > 0; offset--) {
const PADNAME * const name = name_p[offset];
if (name && PadnameLEN(name) == namelen
&& !PadnameOUTER(name)
&& (PadnameIsOUR(name))
&& ( PadnamePV(name) == namepv
|| memEQ(PadnamePV(name), namepv, namelen) )
&& COP_SEQ_RANGE_LOW(name) == PERL_PADSEQ_INTRO
)
return offset;
}
return NOT_IN_PAD;
}
/*
=for apidoc pad_findmy_pv
Exactly like L</pad_findmy_pvn>, but takes a nul-terminated string
instead of a string/length pair.
=cut
*/