forked from schacon/perl
/
op.c
14481 lines (12858 loc) · 410 KB
/
op.c
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#line 2 "op.c"
/* op.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.
*
*/
/*
* 'You see: Mr. Drogo, he married poor Miss Primula Brandybuck. She was
* our Mr. Bilbo's first cousin on the mother's side (her mother being the
* youngest of the Old Took's daughters); and Mr. Drogo was his second
* cousin. So Mr. Frodo is his first *and* second cousin, once removed
* either way, as the saying is, if you follow me.' --the Gaffer
*
* [p.23 of _The Lord of the Rings_, I/i: "A Long-Expected Party"]
*/
/* This file contains the functions that create, manipulate and optimize
* the OP structures that hold a compiled perl program.
*
* A Perl program is compiled into a tree of OPs. Each op contains
* structural pointers (eg to its siblings and the next op in the
* execution sequence), a pointer to the function that would execute the
* op, plus any data specific to that op. For example, an OP_CONST op
* points to the pp_const() function and to an SV containing the constant
* value. When pp_const() is executed, its job is to push that SV onto the
* stack.
*
* OPs are mainly created by the newFOO() functions, which are mainly
* called from the parser (in perly.y) as the code is parsed. For example
* the Perl code $a + $b * $c would cause the equivalent of the following
* to be called (oversimplifying a bit):
*
* newBINOP(OP_ADD, flags,
* newSVREF($a),
* newBINOP(OP_MULTIPLY, flags, newSVREF($b), newSVREF($c))
* )
*
* Note that during the build of miniperl, a temporary copy of this file
* is made, called opmini.c.
*/
/*
Perl's compiler is essentially a 3-pass compiler with interleaved phases:
A bottom-up pass
A top-down pass
An execution-order pass
The bottom-up pass is represented by all the "newOP" routines and
the ck_ routines. The bottom-upness is actually driven by yacc.
So at the point that a ck_ routine fires, we have no idea what the
context is, either upward in the syntax tree, or either forward or
backward in the execution order. (The bottom-up parser builds that
part of the execution order it knows about, but if you follow the "next"
links around, you'll find it's actually a closed loop through the
top level node.)
Whenever the bottom-up parser gets to a node that supplies context to
its components, it invokes that portion of the top-down pass that applies
to that part of the subtree (and marks the top node as processed, so
if a node further up supplies context, it doesn't have to take the
plunge again). As a particular subcase of this, as the new node is
built, it takes all the closed execution loops of its subcomponents
and links them into a new closed loop for the higher level node. But
it's still not the real execution order.
The actual execution order is not known till we get a grammar reduction
to a top-level unit like a subroutine or file that will be called by
"name" rather than via a "next" pointer. At that point, we can call
into peep() to do that code's portion of the 3rd pass. It has to be
recursive, but it's recursive on basic blocks, not on tree nodes.
*/
/* To implement user lexical pragmas, there needs to be a way at run time to
get the compile time state of %^H for that block. Storing %^H in every
block (or even COP) would be very expensive, so a different approach is
taken. The (running) state of %^H is serialised into a tree of HE-like
structs. Stores into %^H are chained onto the current leaf as a struct
refcounted_he * with the key and the value. Deletes from %^H are saved
with a value of PL_sv_placeholder. The state of %^H at any point can be
turned back into a regular HV by walking back up the tree from that point's
leaf, ignoring any key you've already seen (placeholder or not), storing
the rest into the HV structure, then removing the placeholders. Hence
memory is only used to store the %^H deltas from the enclosing COP, rather
than the entire %^H on each COP.
To cause actions on %^H to write out the serialisation records, it has
magic type 'H'. This magic (itself) does nothing, but its presence causes
the values to gain magic type 'h', which has entries for set and clear.
C<Perl_magic_sethint> updates C<PL_compiling.cop_hints_hash> with a store
record, with deletes written by C<Perl_magic_clearhint>. C<SAVEHINTS>
saves the current C<PL_compiling.cop_hints_hash> on the save stack, so that
it will be correctly restored when any inner compiling scope is exited.
*/
#include "EXTERN.h"
#define PERL_IN_OP_C
#include "perl.h"
#include "keywords.h"
#include "feature.h"
#include "regcomp.h"
#define CALL_PEEP(o) PL_peepp(aTHX_ o)
#define CALL_RPEEP(o) PL_rpeepp(aTHX_ o)
#define CALL_OPFREEHOOK(o) if (PL_opfreehook) PL_opfreehook(aTHX_ o)
/* Used to avoid recursion through the op tree in scalarvoid() and
op_free()
*/
#define DEFERRED_OP_STEP 100
#define DEFER_OP(o) \
STMT_START { \
if (UNLIKELY(defer_ix == (defer_stack_alloc-1))) { \
defer_stack_alloc += DEFERRED_OP_STEP; \
assert(defer_stack_alloc > 0); \
Renew(defer_stack, defer_stack_alloc, OP *); \
} \
defer_stack[++defer_ix] = o; \
} STMT_END
#define POP_DEFERRED_OP() (defer_ix >= 0 ? defer_stack[defer_ix--] : (OP *)NULL)
/* remove any leading "empty" ops from the op_next chain whose first
* node's address is stored in op_p. Store the updated address of the
* first node in op_p.
*/
STATIC void
S_prune_chain_head(OP** op_p)
{
while (*op_p
&& ( (*op_p)->op_type == OP_NULL
|| (*op_p)->op_type == OP_SCOPE
|| (*op_p)->op_type == OP_SCALAR
|| (*op_p)->op_type == OP_LINESEQ)
)
*op_p = (*op_p)->op_next;
}
/* See the explanatory comments above struct opslab in op.h. */
#ifdef PERL_DEBUG_READONLY_OPS
# define PERL_SLAB_SIZE 128
# define PERL_MAX_SLAB_SIZE 4096
# include <sys/mman.h>
#endif
#ifndef PERL_SLAB_SIZE
# define PERL_SLAB_SIZE 64
#endif
#ifndef PERL_MAX_SLAB_SIZE
# define PERL_MAX_SLAB_SIZE 2048
#endif
/* rounds up to nearest pointer */
#define SIZE_TO_PSIZE(x) (((x) + sizeof(I32 *) - 1)/sizeof(I32 *))
#define DIFF(o,p) ((size_t)((I32 **)(p) - (I32**)(o)))
static OPSLAB *
S_new_slab(pTHX_ size_t sz)
{
#ifdef PERL_DEBUG_READONLY_OPS
OPSLAB *slab = (OPSLAB *) mmap(0, sz * sizeof(I32 *),
PROT_READ|PROT_WRITE,
MAP_ANON|MAP_PRIVATE, -1, 0);
DEBUG_m(PerlIO_printf(Perl_debug_log, "mapped %lu at %p\n",
(unsigned long) sz, slab));
if (slab == MAP_FAILED) {
perror("mmap failed");
abort();
}
slab->opslab_size = (U16)sz;
#else
OPSLAB *slab = (OPSLAB *)PerlMemShared_calloc(sz, sizeof(I32 *));
#endif
#ifndef WIN32
/* The context is unused in non-Windows */
PERL_UNUSED_CONTEXT;
#endif
slab->opslab_first = (OPSLOT *)((I32 **)slab + sz - 1);
return slab;
}
/* requires double parens and aTHX_ */
#define DEBUG_S_warn(args) \
DEBUG_S( \
PerlIO_printf(Perl_debug_log, "%s", SvPVx_nolen(Perl_mess args)) \
)
void *
Perl_Slab_Alloc(pTHX_ size_t sz)
{
OPSLAB *slab;
OPSLAB *slab2;
OPSLOT *slot;
OP *o;
size_t opsz, space;
/* We only allocate ops from the slab during subroutine compilation.
We find the slab via PL_compcv, hence that must be non-NULL. It could
also be pointing to a subroutine which is now fully set up (CvROOT()
pointing to the top of the optree for that sub), or a subroutine
which isn't using the slab allocator. If our sanity checks aren't met,
don't use a slab, but allocate the OP directly from the heap. */
if (!PL_compcv || CvROOT(PL_compcv)
|| (CvSTART(PL_compcv) && !CvSLABBED(PL_compcv)))
{
o = (OP*)PerlMemShared_calloc(1, sz);
goto gotit;
}
/* While the subroutine is under construction, the slabs are accessed via
CvSTART(), to avoid needing to expand PVCV by one pointer for something
unneeded at runtime. Once a subroutine is constructed, the slabs are
accessed via CvROOT(). So if CvSTART() is NULL, no slab has been
allocated yet. See the commit message for 8be227ab5eaa23f2 for more
details. */
if (!CvSTART(PL_compcv)) {
CvSTART(PL_compcv) =
(OP *)(slab = S_new_slab(aTHX_ PERL_SLAB_SIZE));
CvSLABBED_on(PL_compcv);
slab->opslab_refcnt = 2; /* one for the CV; one for the new OP */
}
else ++(slab = (OPSLAB *)CvSTART(PL_compcv))->opslab_refcnt;
opsz = SIZE_TO_PSIZE(sz);
sz = opsz + OPSLOT_HEADER_P;
/* The slabs maintain a free list of OPs. In particular, constant folding
will free up OPs, so it makes sense to re-use them where possible. A
freed up slot is used in preference to a new allocation. */
if (slab->opslab_freed) {
OP **too = &slab->opslab_freed;
o = *too;
DEBUG_S_warn((aTHX_ "found free op at %p, slab %p", (void*)o, (void*)slab));
while (o && DIFF(OpSLOT(o), OpSLOT(o)->opslot_next) < sz) {
DEBUG_S_warn((aTHX_ "Alas! too small"));
o = *(too = &o->op_next);
if (o) { DEBUG_S_warn((aTHX_ "found another free op at %p", (void*)o)); }
}
if (o) {
*too = o->op_next;
Zero(o, opsz, I32 *);
o->op_slabbed = 1;
goto gotit;
}
}
#define INIT_OPSLOT \
slot->opslot_slab = slab; \
slot->opslot_next = slab2->opslab_first; \
slab2->opslab_first = slot; \
o = &slot->opslot_op; \
o->op_slabbed = 1
/* The partially-filled slab is next in the chain. */
slab2 = slab->opslab_next ? slab->opslab_next : slab;
if ((space = DIFF(&slab2->opslab_slots, slab2->opslab_first)) < sz) {
/* Remaining space is too small. */
/* If we can fit a BASEOP, add it to the free chain, so as not
to waste it. */
if (space >= SIZE_TO_PSIZE(sizeof(OP)) + OPSLOT_HEADER_P) {
slot = &slab2->opslab_slots;
INIT_OPSLOT;
o->op_type = OP_FREED;
o->op_next = slab->opslab_freed;
slab->opslab_freed = o;
}
/* Create a new slab. Make this one twice as big. */
slot = slab2->opslab_first;
while (slot->opslot_next) slot = slot->opslot_next;
slab2 = S_new_slab(aTHX_
(DIFF(slab2, slot)+1)*2 > PERL_MAX_SLAB_SIZE
? PERL_MAX_SLAB_SIZE
: (DIFF(slab2, slot)+1)*2);
slab2->opslab_next = slab->opslab_next;
slab->opslab_next = slab2;
}
assert(DIFF(&slab2->opslab_slots, slab2->opslab_first) >= sz);
/* Create a new op slot */
slot = (OPSLOT *)((I32 **)slab2->opslab_first - sz);
assert(slot >= &slab2->opslab_slots);
if (DIFF(&slab2->opslab_slots, slot)
< SIZE_TO_PSIZE(sizeof(OP)) + OPSLOT_HEADER_P)
slot = &slab2->opslab_slots;
INIT_OPSLOT;
DEBUG_S_warn((aTHX_ "allocating op at %p, slab %p", (void*)o, (void*)slab));
gotit:
#ifdef PERL_OP_PARENT
/* moresib == 0, op_sibling == 0 implies a solitary unattached op */
assert(!o->op_moresib);
assert(!o->op_sibparent);
#endif
return (void *)o;
}
#undef INIT_OPSLOT
#ifdef PERL_DEBUG_READONLY_OPS
void
Perl_Slab_to_ro(pTHX_ OPSLAB *slab)
{
PERL_ARGS_ASSERT_SLAB_TO_RO;
if (slab->opslab_readonly) return;
slab->opslab_readonly = 1;
for (; slab; slab = slab->opslab_next) {
/*DEBUG_U(PerlIO_printf(Perl_debug_log,"mprotect ->ro %lu at %p\n",
(unsigned long) slab->opslab_size, slab));*/
if (mprotect(slab, slab->opslab_size * sizeof(I32 *), PROT_READ))
Perl_warn(aTHX_ "mprotect for %p %lu failed with %d", slab,
(unsigned long)slab->opslab_size, errno);
}
}
void
Perl_Slab_to_rw(pTHX_ OPSLAB *const slab)
{
OPSLAB *slab2;
PERL_ARGS_ASSERT_SLAB_TO_RW;
if (!slab->opslab_readonly) return;
slab2 = slab;
for (; slab2; slab2 = slab2->opslab_next) {
/*DEBUG_U(PerlIO_printf(Perl_debug_log,"mprotect ->rw %lu at %p\n",
(unsigned long) size, slab2));*/
if (mprotect((void *)slab2, slab2->opslab_size * sizeof(I32 *),
PROT_READ|PROT_WRITE)) {
Perl_warn(aTHX_ "mprotect RW for %p %lu failed with %d", slab,
(unsigned long)slab2->opslab_size, errno);
}
}
slab->opslab_readonly = 0;
}
#else
# define Slab_to_rw(op) NOOP
#endif
/* This cannot possibly be right, but it was copied from the old slab
allocator, to which it was originally added, without explanation, in
commit 083fcd5. */
#ifdef NETWARE
# define PerlMemShared PerlMem
#endif
void
Perl_Slab_Free(pTHX_ void *op)
{
OP * const o = (OP *)op;
OPSLAB *slab;
PERL_ARGS_ASSERT_SLAB_FREE;
if (!o->op_slabbed) {
if (!o->op_static)
PerlMemShared_free(op);
return;
}
slab = OpSLAB(o);
/* If this op is already freed, our refcount will get screwy. */
assert(o->op_type != OP_FREED);
o->op_type = OP_FREED;
o->op_next = slab->opslab_freed;
slab->opslab_freed = o;
DEBUG_S_warn((aTHX_ "free op at %p, recorded in slab %p", (void*)o, (void*)slab));
OpslabREFCNT_dec_padok(slab);
}
void
Perl_opslab_free_nopad(pTHX_ OPSLAB *slab)
{
const bool havepad = !!PL_comppad;
PERL_ARGS_ASSERT_OPSLAB_FREE_NOPAD;
if (havepad) {
ENTER;
PAD_SAVE_SETNULLPAD();
}
opslab_free(slab);
if (havepad) LEAVE;
}
void
Perl_opslab_free(pTHX_ OPSLAB *slab)
{
OPSLAB *slab2;
PERL_ARGS_ASSERT_OPSLAB_FREE;
PERL_UNUSED_CONTEXT;
DEBUG_S_warn((aTHX_ "freeing slab %p", (void*)slab));
assert(slab->opslab_refcnt == 1);
do {
slab2 = slab->opslab_next;
#ifdef DEBUGGING
slab->opslab_refcnt = ~(size_t)0;
#endif
#ifdef PERL_DEBUG_READONLY_OPS
DEBUG_m(PerlIO_printf(Perl_debug_log, "Deallocate slab at %p\n",
(void*)slab));
if (munmap(slab, slab->opslab_size * sizeof(I32 *))) {
perror("munmap failed");
abort();
}
#else
PerlMemShared_free(slab);
#endif
slab = slab2;
} while (slab);
}
void
Perl_opslab_force_free(pTHX_ OPSLAB *slab)
{
OPSLAB *slab2;
OPSLOT *slot;
#ifdef DEBUGGING
size_t savestack_count = 0;
#endif
PERL_ARGS_ASSERT_OPSLAB_FORCE_FREE;
slab2 = slab;
do {
for (slot = slab2->opslab_first;
slot->opslot_next;
slot = slot->opslot_next) {
if (slot->opslot_op.op_type != OP_FREED
&& !(slot->opslot_op.op_savefree
#ifdef DEBUGGING
&& ++savestack_count
#endif
)
) {
assert(slot->opslot_op.op_slabbed);
op_free(&slot->opslot_op);
if (slab->opslab_refcnt == 1) goto free;
}
}
} while ((slab2 = slab2->opslab_next));
/* > 1 because the CV still holds a reference count. */
if (slab->opslab_refcnt > 1) { /* still referenced by the savestack */
#ifdef DEBUGGING
assert(savestack_count == slab->opslab_refcnt-1);
#endif
/* Remove the CV’s reference count. */
slab->opslab_refcnt--;
return;
}
free:
opslab_free(slab);
}
#ifdef PERL_DEBUG_READONLY_OPS
OP *
Perl_op_refcnt_inc(pTHX_ OP *o)
{
if(o) {
OPSLAB *const slab = o->op_slabbed ? OpSLAB(o) : NULL;
if (slab && slab->opslab_readonly) {
Slab_to_rw(slab);
++o->op_targ;
Slab_to_ro(slab);
} else {
++o->op_targ;
}
}
return o;
}
PADOFFSET
Perl_op_refcnt_dec(pTHX_ OP *o)
{
PADOFFSET result;
OPSLAB *const slab = o->op_slabbed ? OpSLAB(o) : NULL;
PERL_ARGS_ASSERT_OP_REFCNT_DEC;
if (slab && slab->opslab_readonly) {
Slab_to_rw(slab);
result = --o->op_targ;
Slab_to_ro(slab);
} else {
result = --o->op_targ;
}
return result;
}
#endif
/*
* In the following definition, the ", (OP*)0" is just to make the compiler
* think the expression is of the right type: croak actually does a Siglongjmp.
*/
#define CHECKOP(type,o) \
((PL_op_mask && PL_op_mask[type]) \
? ( op_free((OP*)o), \
Perl_croak(aTHX_ "'%s' trapped by operation mask", PL_op_desc[type]), \
(OP*)0 ) \
: PL_check[type](aTHX_ (OP*)o))
#define RETURN_UNLIMITED_NUMBER (PERL_INT_MAX / 2)
#define OpTYPE_set(o,type) \
STMT_START { \
o->op_type = (OPCODE)type; \
o->op_ppaddr = PL_ppaddr[type]; \
} STMT_END
STATIC OP *
S_no_fh_allowed(pTHX_ OP *o)
{
PERL_ARGS_ASSERT_NO_FH_ALLOWED;
yyerror(Perl_form(aTHX_ "Missing comma after first argument to %s function",
OP_DESC(o)));
return o;
}
STATIC OP *
S_too_few_arguments_pv(pTHX_ OP *o, const char* name, U32 flags)
{
PERL_ARGS_ASSERT_TOO_FEW_ARGUMENTS_PV;
yyerror_pv(Perl_form(aTHX_ "Not enough arguments for %s", name), flags);
return o;
}
STATIC OP *
S_too_many_arguments_pv(pTHX_ OP *o, const char *name, U32 flags)
{
PERL_ARGS_ASSERT_TOO_MANY_ARGUMENTS_PV;
yyerror_pv(Perl_form(aTHX_ "Too many arguments for %s", name), flags);
return o;
}
STATIC void
S_bad_type_pv(pTHX_ I32 n, const char *t, const OP *o, const OP *kid)
{
PERL_ARGS_ASSERT_BAD_TYPE_PV;
yyerror_pv(Perl_form(aTHX_ "Type of arg %d to %s must be %s (not %s)",
(int)n, PL_op_desc[(o)->op_type], t, OP_DESC(kid)), 0);
}
/* remove flags var, its unused in all callers, move to to right end since gv
and kid are always the same */
STATIC void
S_bad_type_gv(pTHX_ I32 n, GV *gv, const OP *kid, const char *t)
{
SV * const namesv = cv_name((CV *)gv, NULL, 0);
PERL_ARGS_ASSERT_BAD_TYPE_GV;
yyerror_pv(Perl_form(aTHX_ "Type of arg %d to %"SVf" must be %s (not %s)",
(int)n, SVfARG(namesv), t, OP_DESC(kid)), SvUTF8(namesv));
}
STATIC void
S_no_bareword_allowed(pTHX_ OP *o)
{
PERL_ARGS_ASSERT_NO_BAREWORD_ALLOWED;
qerror(Perl_mess(aTHX_
"Bareword \"%"SVf"\" not allowed while \"strict subs\" in use",
SVfARG(cSVOPo_sv)));
o->op_private &= ~OPpCONST_STRICT; /* prevent warning twice about the same OP */
}
/* "register" allocation */
PADOFFSET
Perl_allocmy(pTHX_ const char *const name, const STRLEN len, const U32 flags)
{
PADOFFSET off;
const bool is_our = (PL_parser->in_my == KEY_our);
PERL_ARGS_ASSERT_ALLOCMY;
if (flags & ~SVf_UTF8)
Perl_croak(aTHX_ "panic: allocmy illegal flag bits 0x%" UVxf,
(UV)flags);
/* complain about "my $<special_var>" etc etc */
if (len &&
!(is_our ||
isALPHA(name[1]) ||
((flags & SVf_UTF8) && isIDFIRST_utf8((U8 *)name+1)) ||
(name[1] == '_' && (*name == '$' || len > 2))))
{
if (!(flags & SVf_UTF8 && UTF8_IS_START(name[1]))
&& isASCII(name[1])
&& (!isPRINT(name[1]) || strchr("\t\n\r\f", name[1]))) {
yyerror(Perl_form(aTHX_ "Can't use global %c^%c%.*s in \"%s\"",
name[0], toCTRL(name[1]), (int)(len - 2), name + 2,
PL_parser->in_my == KEY_state ? "state" : "my"));
} else {
yyerror_pv(Perl_form(aTHX_ "Can't use global %.*s in \"%s\"", (int) len, name,
PL_parser->in_my == KEY_state ? "state" : "my"), flags & SVf_UTF8);
}
}
else if (len == 2 && name[1] == '_' && !is_our)
/* diag_listed_as: Use of my $_ is experimental */
Perl_ck_warner_d(aTHX_ packWARN(WARN_EXPERIMENTAL__LEXICAL_TOPIC),
"Use of %s $_ is experimental",
PL_parser->in_my == KEY_state
? "state"
: "my");
/* allocate a spare slot and store the name in that slot */
off = pad_add_name_pvn(name, len,
(is_our ? padadd_OUR :
PL_parser->in_my == KEY_state ? padadd_STATE : 0),
PL_parser->in_my_stash,
(is_our
/* $_ is always in main::, even with our */
? (PL_curstash && !memEQs(name,len,"$_")
? PL_curstash
: PL_defstash)
: NULL
)
);
/* anon sub prototypes contains state vars should always be cloned,
* otherwise the state var would be shared between anon subs */
if (PL_parser->in_my == KEY_state && CvANON(PL_compcv))
CvCLONE_on(PL_compcv);
return off;
}
/*
=head1 Optree Manipulation Functions
=for apidoc alloccopstash
Available only under threaded builds, this function allocates an entry in
C<PL_stashpad> for the stash passed to it.
=cut
*/
#ifdef USE_ITHREADS
PADOFFSET
Perl_alloccopstash(pTHX_ HV *hv)
{
PADOFFSET off = 0, o = 1;
bool found_slot = FALSE;
PERL_ARGS_ASSERT_ALLOCCOPSTASH;
if (PL_stashpad[PL_stashpadix] == hv) return PL_stashpadix;
for (; o < PL_stashpadmax; ++o) {
if (PL_stashpad[o] == hv) return PL_stashpadix = o;
if (!PL_stashpad[o] || SvTYPE(PL_stashpad[o]) != SVt_PVHV)
found_slot = TRUE, off = o;
}
if (!found_slot) {
Renew(PL_stashpad, PL_stashpadmax + 10, HV *);
Zero(PL_stashpad + PL_stashpadmax, 10, HV *);
off = PL_stashpadmax;
PL_stashpadmax += 10;
}
PL_stashpad[PL_stashpadix = off] = hv;
return off;
}
#endif
/* free the body of an op without examining its contents.
* Always use this rather than FreeOp directly */
static void
S_op_destroy(pTHX_ OP *o)
{
FreeOp(o);
}
/* Destructor */
/*
=for apidoc Am|void|op_free|OP *o
Free an op. Only use this when an op is no longer linked to from any
optree.
=cut
*/
void
Perl_op_free(pTHX_ OP *o)
{
dVAR;
OPCODE type;
SSize_t defer_ix = -1;
SSize_t defer_stack_alloc = 0;
OP **defer_stack = NULL;
do {
/* Though ops may be freed twice, freeing the op after its slab is a
big no-no. */
assert(!o || !o->op_slabbed || OpSLAB(o)->opslab_refcnt != ~(size_t)0);
/* During the forced freeing of ops after compilation failure, kidops
may be freed before their parents. */
if (!o || o->op_type == OP_FREED)
continue;
type = o->op_type;
/* an op should only ever acquire op_private flags that we know about.
* If this fails, you may need to fix something in regen/op_private */
if (o->op_ppaddr == PL_ppaddr[o->op_type]) {
assert(!(o->op_private & ~PL_op_private_valid[type]));
}
if (o->op_private & OPpREFCOUNTED) {
switch (type) {
case OP_LEAVESUB:
case OP_LEAVESUBLV:
case OP_LEAVEEVAL:
case OP_LEAVE:
case OP_SCOPE:
case OP_LEAVEWRITE:
{
PADOFFSET refcnt;
OP_REFCNT_LOCK;
refcnt = OpREFCNT_dec(o);
OP_REFCNT_UNLOCK;
if (refcnt) {
/* Need to find and remove any pattern match ops from the list
we maintain for reset(). */
find_and_forget_pmops(o);
continue;
}
}
break;
default:
break;
}
}
/* Call the op_free hook if it has been set. Do it now so that it's called
* at the right time for refcounted ops, but still before all of the kids
* are freed. */
CALL_OPFREEHOOK(o);
if (o->op_flags & OPf_KIDS) {
OP *kid, *nextkid;
for (kid = cUNOPo->op_first; kid; kid = nextkid) {
nextkid = OpSIBLING(kid); /* Get before next freeing kid */
if (!kid || kid->op_type == OP_FREED)
/* During the forced freeing of ops after
compilation failure, kidops may be freed before
their parents. */
continue;
if (!(kid->op_flags & OPf_KIDS))
/* If it has no kids, just free it now */
op_free(kid);
else
DEFER_OP(kid);
}
}
if (type == OP_NULL)
type = (OPCODE)o->op_targ;
if (o->op_slabbed)
Slab_to_rw(OpSLAB(o));
/* COP* is not cleared by op_clear() so that we may track line
* numbers etc even after null() */
if (type == OP_NEXTSTATE || type == OP_DBSTATE) {
cop_free((COP*)o);
}
op_clear(o);
FreeOp(o);
#ifdef DEBUG_LEAKING_SCALARS
if (PL_op == o)
PL_op = NULL;
#endif
} while ( (o = POP_DEFERRED_OP()) );
Safefree(defer_stack);
}
/* S_op_clear_gv(): free a GV attached to an OP */
#ifdef USE_ITHREADS
void S_op_clear_gv(pTHX_ OP *o, PADOFFSET *ixp)
#else
void S_op_clear_gv(pTHX_ OP *o, SV**svp)
#endif
{
GV *gv = (o->op_type == OP_GV || o->op_type == OP_GVSV
|| o->op_type == OP_MULTIDEREF)
#ifdef USE_ITHREADS
&& PL_curpad
? ((GV*)PAD_SVl(*ixp)) : NULL;
#else
? (GV*)(*svp) : NULL;
#endif
/* It's possible during global destruction that the GV is freed
before the optree. Whilst the SvREFCNT_inc is happy to bump from
0 to 1 on a freed SV, the corresponding SvREFCNT_dec from 1 to 0
will trigger an assertion failure, because the entry to sv_clear
checks that the scalar is not already freed. A check of for
!SvIS_FREED(gv) turns out to be invalid, because during global
destruction the reference count can be forced down to zero
(with SVf_BREAK set). In which case raising to 1 and then
dropping to 0 triggers cleanup before it should happen. I
*think* that this might actually be a general, systematic,
weakness of the whole idea of SVf_BREAK, in that code *is*
allowed to raise and lower references during global destruction,
so any *valid* code that happens to do this during global
destruction might well trigger premature cleanup. */
bool still_valid = gv && SvREFCNT(gv);
if (still_valid)
SvREFCNT_inc_simple_void(gv);
#ifdef USE_ITHREADS
if (*ixp > 0) {
pad_swipe(*ixp, TRUE);
*ixp = 0;
}
#else
SvREFCNT_dec(*svp);
*svp = NULL;
#endif
if (still_valid) {
int try_downgrade = SvREFCNT(gv) == 2;
SvREFCNT_dec_NN(gv);
if (try_downgrade)
gv_try_downgrade(gv);
}
}
void
Perl_op_clear(pTHX_ OP *o)
{
dVAR;
PERL_ARGS_ASSERT_OP_CLEAR;
switch (o->op_type) {
case OP_NULL: /* Was holding old type, if any. */
/* FALLTHROUGH */
case OP_ENTERTRY:
case OP_ENTEREVAL: /* Was holding hints. */
o->op_targ = 0;
break;
default:
if (!(o->op_flags & OPf_REF)
|| (PL_check[o->op_type] != Perl_ck_ftst))
break;
/* FALLTHROUGH */
case OP_GVSV:
case OP_GV:
case OP_AELEMFAST:
#ifdef USE_ITHREADS
S_op_clear_gv(aTHX_ o, &(cPADOPx(o)->op_padix));
#else
S_op_clear_gv(aTHX_ o, &(cSVOPx(o)->op_sv));
#endif
break;
case OP_METHOD_REDIR:
case OP_METHOD_REDIR_SUPER:
#ifdef USE_ITHREADS
if (cMETHOPx(o)->op_rclass_targ) {
pad_swipe(cMETHOPx(o)->op_rclass_targ, 1);
cMETHOPx(o)->op_rclass_targ = 0;
}
#else
SvREFCNT_dec(cMETHOPx(o)->op_rclass_sv);
cMETHOPx(o)->op_rclass_sv = NULL;
#endif
case OP_METHOD_NAMED:
case OP_METHOD_SUPER:
SvREFCNT_dec(cMETHOPx(o)->op_u.op_meth_sv);
cMETHOPx(o)->op_u.op_meth_sv = NULL;
#ifdef USE_ITHREADS
if (o->op_targ) {
pad_swipe(o->op_targ, 1);
o->op_targ = 0;
}
#endif
break;
case OP_CONST:
case OP_HINTSEVAL:
SvREFCNT_dec(cSVOPo->op_sv);
cSVOPo->op_sv = NULL;
#ifdef USE_ITHREADS
/** Bug #15654
Even if op_clear does a pad_free for the target of the op,
pad_free doesn't actually remove the sv that exists in the pad;
instead it lives on. This results in that it could be reused as
a target later on when the pad was reallocated.
**/
if(o->op_targ) {
pad_swipe(o->op_targ,1);
o->op_targ = 0;
}
#endif
break;
case OP_DUMP:
case OP_GOTO:
case OP_NEXT:
case OP_LAST:
case OP_REDO:
if (o->op_flags & (OPf_SPECIAL|OPf_STACKED|OPf_KIDS))
break;
/* FALLTHROUGH */
case OP_TRANS:
case OP_TRANSR:
if (o->op_private & (OPpTRANS_FROM_UTF|OPpTRANS_TO_UTF)) {
assert(o->op_type == OP_TRANS || o->op_type == OP_TRANSR);
#ifdef USE_ITHREADS
if (cPADOPo->op_padix > 0) {
pad_swipe(cPADOPo->op_padix, TRUE);
cPADOPo->op_padix = 0;
}
#else
SvREFCNT_dec(cSVOPo->op_sv);
cSVOPo->op_sv = NULL;
#endif
}
else {
PerlMemShared_free(cPVOPo->op_pv);
cPVOPo->op_pv = NULL;
}
break;
case OP_SUBST:
op_free(cPMOPo->op_pmreplrootu.op_pmreplroot);
goto clear_pmop;
case OP_PUSHRE:
#ifdef USE_ITHREADS
if (cPMOPo->op_pmreplrootu.op_pmtargetoff) {
pad_swipe(cPMOPo->op_pmreplrootu.op_pmtargetoff, TRUE);
}
#else
SvREFCNT_dec(MUTABLE_SV(cPMOPo->op_pmreplrootu.op_pmtargetgv));
#endif
/* FALLTHROUGH */
case OP_MATCH:
case OP_QR:
clear_pmop:
if (!(cPMOPo->op_pmflags & PMf_CODELIST_PRIVATE))
op_free(cPMOPo->op_code_list);
cPMOPo->op_code_list = NULL;
forget_pmop(cPMOPo);
cPMOPo->op_pmreplrootu.op_pmreplroot = NULL;
/* we use the same protection as the "SAFE" version of the PM_ macros
* here since sv_clean_all might release some PMOPs
* after PL_regex_padav has been cleared
* and the clearing of PL_regex_padav needs to
* happen before sv_clean_all
*/
#ifdef USE_ITHREADS
if(PL_regex_pad) { /* We could be in destruction */
const IV offset = (cPMOPo)->op_pmoffset;
ReREFCNT_dec(PM_GETRE(cPMOPo));
PL_regex_pad[offset] = &PL_sv_undef;
sv_catpvn_nomg(PL_regex_pad[0], (const char *)&offset,
sizeof(offset));
}
#else
ReREFCNT_dec(PM_GETRE(cPMOPo));
PM_SETRE(cPMOPo, NULL);
#endif
break;
case OP_MULTIDEREF:
{
UNOP_AUX_item *items = cUNOP_AUXo->op_aux;
UV actions = items->uv;
bool last = 0;
bool is_hash = FALSE;
while (!last) {
switch (actions & MDEREF_ACTION_MASK) {
case MDEREF_reload:
actions = (++items)->uv;
continue;
case MDEREF_HV_padhv_helem: