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[perl5.git] / cop.h
1 /*    cop.h
2  *
3  *    Copyright (c) 1991-2000, Larry Wall
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  */
9
10 struct cop {
11     BASEOP
12     char *      cop_label;      /* label for this construct */
13 #ifdef USE_ITHREADS
14     char *      cop_stashpv;    /* package line was compiled in */
15     char *      cop_file;       /* file name the following line # is from */
16 #else
17     HV *        cop_stash;      /* package line was compiled in */
18     GV *        cop_filegv;     /* file the following line # is from */
19 #endif
20     U32         cop_seq;        /* parse sequence number */
21     I32         cop_arybase;    /* array base this line was compiled with */
22     line_t      cop_line;       /* line # of this command */
23     SV *        cop_warnings;   /* lexical warnings bitmask */
24     SV *        cop_io;         /* lexical IO defaults */
25 };
26
27 #define Nullcop Null(COP*)
28
29 #ifdef USE_ITHREADS
30 #  define CopFILE(c)            ((c)->cop_file)
31 #  define CopFILEGV(c)          (CopFILE(c) \
32                                  ? gv_fetchfile(CopFILE(c)) : Nullgv)
33 #  define CopFILE_set(c,pv)     ((c)->cop_file = savepv(pv))
34 #  define CopFILESV(c)          (CopFILE(c) \
35                                  ? GvSV(gv_fetchfile(CopFILE(c))) : Nullsv)
36 #  define CopFILEAV(c)          (CopFILE(c) \
37                                  ? GvAV(gv_fetchfile(CopFILE(c))) : Nullav)
38 #  define CopSTASHPV(c)         ((c)->cop_stashpv)
39 #  define CopSTASHPV_set(c,pv)  ((c)->cop_stashpv = ((pv) ? savepv(pv) : Nullch))
40 #  define CopSTASH(c)           (CopSTASHPV(c) \
41                                  ? gv_stashpv(CopSTASHPV(c),GV_ADD) : Nullhv)
42 #  define CopSTASH_set(c,hv)    CopSTASHPV_set(c, (hv) ? HvNAME(hv) : Nullch)
43 #  define CopSTASH_eq(c,hv)     ((hv)                                   \
44                                  && (CopSTASHPV(c) == HvNAME(hv)        \
45                                      || (CopSTASHPV(c) && HvNAME(hv)    \
46                                          && strEQ(CopSTASHPV(c), HvNAME(hv)))))
47 #else
48 #  define CopFILEGV(c)          ((c)->cop_filegv)
49 #  define CopFILEGV_set(c,gv)   ((c)->cop_filegv = (GV*)SvREFCNT_inc(gv))
50 #  define CopFILE_set(c,pv)     CopFILEGV_set((c), gv_fetchfile(pv))
51 #  define CopFILESV(c)          (CopFILEGV(c) ? GvSV(CopFILEGV(c)) : Nullsv)
52 #  define CopFILEAV(c)          (CopFILEGV(c) ? GvAV(CopFILEGV(c)) : Nullav)
53 #  define CopFILE(c)            (CopFILESV(c) ? SvPVX(CopFILESV(c)) : Nullch)
54 #  define CopSTASH(c)           ((c)->cop_stash)
55 #  define CopSTASH_set(c,hv)    ((c)->cop_stash = (hv))
56 #  define CopSTASHPV(c)         (CopSTASH(c) ? HvNAME(CopSTASH(c)) : Nullch)
57    /* cop_stash is not refcounted */
58 #  define CopSTASHPV_set(c,pv)  CopSTASH_set((c), gv_stashpv(pv,GV_ADD))
59 #  define CopSTASH_eq(c,hv)     (CopSTASH(c) == (hv))
60 #endif /* USE_ITHREADS */
61
62 #define CopSTASH_ne(c,hv)       (!CopSTASH_eq(c,hv))
63 #define CopLINE(c)              ((c)->cop_line)
64 #define CopLINE_inc(c)          (++CopLINE(c))
65 #define CopLINE_dec(c)          (--CopLINE(c))
66 #define CopLINE_set(c,l)        (CopLINE(c) = (l))
67
68 /*
69  * Here we have some enormously heavy (or at least ponderous) wizardry.
70  */
71
72 /* subroutine context */
73 struct block_sub {
74     CV *        cv;
75     GV *        gv;
76     GV *        dfoutgv;
77 #ifndef USE_THREADS
78     AV *        savearray;
79 #endif /* USE_THREADS */
80     AV *        argarray;
81     U16         olddepth;
82     U8          hasargs;
83     U8          lval;           /* XXX merge lval and hasargs? */
84     SV **       oldcurpad;
85 };
86
87 #define PUSHSUB(cx)                                                     \
88         cx->blk_sub.cv = cv;                                            \
89         cx->blk_sub.olddepth = CvDEPTH(cv);                             \
90         cx->blk_sub.hasargs = hasargs;                                  \
91         cx->blk_sub.lval = PL_op->op_private &                          \
92                               (OPpLVAL_INTRO|OPpENTERSUB_INARGS);
93
94 #define PUSHFORMAT(cx)                                                  \
95         cx->blk_sub.cv = cv;                                            \
96         cx->blk_sub.gv = gv;                                            \
97         cx->blk_sub.hasargs = 0;                                        \
98         cx->blk_sub.dfoutgv = PL_defoutgv;                              \
99         (void)SvREFCNT_inc(cx->blk_sub.dfoutgv)
100
101 #ifdef USE_THREADS
102 #  define POP_SAVEARRAY() NOOP
103 #else
104 #  define POP_SAVEARRAY()                                               \
105     STMT_START {                                                        \
106         SvREFCNT_dec(GvAV(PL_defgv));                                   \
107         GvAV(PL_defgv) = cx->blk_sub.savearray;                         \
108     } STMT_END
109 #endif /* USE_THREADS */
110
111 /* junk in @_ spells trouble when cloning CVs and in pp_caller(), so don't
112  * leave any (a fast av_clear(ary), basically) */
113 #define CLEAR_ARGARRAY(ary) \
114     STMT_START {                                                        \
115         AvMAX(ary) += AvARRAY(ary) - AvALLOC(ary);                      \
116         SvPVX(ary) = (char*)AvALLOC(ary);                               \
117         AvFILLp(ary) = -1;                                              \
118     } STMT_END
119
120 #define POPSUB(cx,sv)                                                   \
121     STMT_START {                                                        \
122         if (cx->blk_sub.hasargs) {                                      \
123             POP_SAVEARRAY();                                            \
124             /* abandon @_ if it got reified */                          \
125             if (AvREAL(cx->blk_sub.argarray)) {                         \
126                 SSize_t fill = AvFILLp(cx->blk_sub.argarray);           \
127                 SvREFCNT_dec(cx->blk_sub.argarray);                     \
128                 cx->blk_sub.argarray = newAV();                         \
129                 av_extend(cx->blk_sub.argarray, fill);                  \
130                 AvFLAGS(cx->blk_sub.argarray) = AVf_REIFY;              \
131                 cx->blk_sub.oldcurpad[0] = (SV*)cx->blk_sub.argarray;   \
132             }                                                           \
133             else {                                                      \
134                 CLEAR_ARGARRAY(cx->blk_sub.argarray);                   \
135             }                                                           \
136         }                                                               \
137         sv = (SV*)cx->blk_sub.cv;                                       \
138         if (sv && (CvDEPTH((CV*)sv) = cx->blk_sub.olddepth))            \
139             sv = Nullsv;                                                \
140     } STMT_END
141
142 #define LEAVESUB(sv)                                                    \
143     STMT_START {                                                        \
144         if (sv)                                                         \
145             SvREFCNT_dec(sv);                                           \
146     } STMT_END
147
148 #define POPFORMAT(cx)                                                   \
149         setdefout(cx->blk_sub.dfoutgv);                                 \
150         SvREFCNT_dec(cx->blk_sub.dfoutgv);
151
152 /* eval context */
153 struct block_eval {
154     I32         old_in_eval;
155     I32         old_op_type;
156     SV *        old_namesv;
157     OP *        old_eval_root;
158     SV *        cur_text;
159 };
160
161 #define PUSHEVAL(cx,n,fgv)                                              \
162     STMT_START {                                                        \
163         cx->blk_eval.old_in_eval = PL_in_eval;                          \
164         cx->blk_eval.old_op_type = PL_op->op_type;                      \
165         cx->blk_eval.old_namesv = (n ? newSVpv(n,0) : Nullsv);          \
166         cx->blk_eval.old_eval_root = PL_eval_root;                      \
167         cx->blk_eval.cur_text = PL_linestr;                             \
168     } STMT_END
169
170 #define POPEVAL(cx)                                                     \
171     STMT_START {                                                        \
172         PL_in_eval = cx->blk_eval.old_in_eval;                          \
173         optype = cx->blk_eval.old_op_type;                              \
174         PL_eval_root = cx->blk_eval.old_eval_root;                      \
175         if (cx->blk_eval.old_namesv)                                    \
176             sv_2mortal(cx->blk_eval.old_namesv);                        \
177     } STMT_END
178
179 /* loop context */
180 struct block_loop {
181     char *      label;
182     I32         resetsp;
183     OP *        redo_op;
184     OP *        next_op;
185     OP *        last_op;
186 #ifdef USE_ITHREADS
187     void *      iterdata;
188     SV **       oldcurpad;
189 #else
190     SV **       itervar;
191 #endif
192     SV *        itersave;
193     SV *        iterlval;
194     AV *        iterary;
195     IV          iterix;
196     IV          itermax;
197 };
198
199 #ifdef USE_ITHREADS
200 #  define CxITERVAR(c)                                                  \
201         ((c)->blk_loop.iterdata                                         \
202          ? (CxPADLOOP(cx)                                               \
203             ? &((c)->blk_loop.oldcurpad)[(PADOFFSET)(c)->blk_loop.iterdata]     \
204             : &GvSV((GV*)(c)->blk_loop.iterdata))                       \
205          : (SV**)NULL)
206 #  define CX_ITERDATA_SET(cx,idata)                                     \
207         cx->blk_loop.oldcurpad = PL_curpad;                             \
208         if ((cx->blk_loop.iterdata = (idata)))                          \
209             cx->blk_loop.itersave = SvREFCNT_inc(*CxITERVAR(cx));
210 #else
211 #  define CxITERVAR(c)          ((c)->blk_loop.itervar)
212 #  define CX_ITERDATA_SET(cx,ivar)                                      \
213         if ((cx->blk_loop.itervar = (SV**)(ivar)))                      \
214             cx->blk_loop.itersave = SvREFCNT_inc(*CxITERVAR(cx));
215 #endif
216
217 #define PUSHLOOP(cx, dat, s)                                            \
218         cx->blk_loop.label = PL_curcop->cop_label;                      \
219         cx->blk_loop.resetsp = s - PL_stack_base;                       \
220         cx->blk_loop.redo_op = cLOOP->op_redoop;                        \
221         cx->blk_loop.next_op = cLOOP->op_nextop;                        \
222         cx->blk_loop.last_op = cLOOP->op_lastop;                        \
223         cx->blk_loop.iterlval = Nullsv;                                 \
224         cx->blk_loop.iterary = Nullav;                                  \
225         cx->blk_loop.iterix = -1;                                       \
226         CX_ITERDATA_SET(cx,dat);
227
228 #define POPLOOP(cx)                                                     \
229         SvREFCNT_dec(cx->blk_loop.iterlval);                            \
230         if (CxITERVAR(cx)) {                                            \
231             SV **s_v_p = CxITERVAR(cx);                                 \
232             sv_2mortal(*s_v_p);                                         \
233             *s_v_p = cx->blk_loop.itersave;                             \
234         }                                                               \
235         if (cx->blk_loop.iterary && cx->blk_loop.iterary != PL_curstack)\
236             SvREFCNT_dec(cx->blk_loop.iterary);
237
238 /* context common to subroutines, evals and loops */
239 struct block {
240     I32         blku_oldsp;     /* stack pointer to copy stuff down to */
241     COP *       blku_oldcop;    /* old curcop pointer */
242     I32         blku_oldretsp;  /* return stack index */
243     I32         blku_oldmarksp; /* mark stack index */
244     I32         blku_oldscopesp;        /* scope stack index */
245     PMOP *      blku_oldpm;     /* values of pattern match vars */
246     U8          blku_gimme;     /* is this block running in list context? */
247
248     union {
249         struct block_sub        blku_sub;
250         struct block_eval       blku_eval;
251         struct block_loop       blku_loop;
252     } blk_u;
253 };
254 #define blk_oldsp       cx_u.cx_blk.blku_oldsp
255 #define blk_oldcop      cx_u.cx_blk.blku_oldcop
256 #define blk_oldretsp    cx_u.cx_blk.blku_oldretsp
257 #define blk_oldmarksp   cx_u.cx_blk.blku_oldmarksp
258 #define blk_oldscopesp  cx_u.cx_blk.blku_oldscopesp
259 #define blk_oldpm       cx_u.cx_blk.blku_oldpm
260 #define blk_gimme       cx_u.cx_blk.blku_gimme
261 #define blk_sub         cx_u.cx_blk.blk_u.blku_sub
262 #define blk_eval        cx_u.cx_blk.blk_u.blku_eval
263 #define blk_loop        cx_u.cx_blk.blk_u.blku_loop
264
265 /* Enter a block. */
266 #define PUSHBLOCK(cx,t,sp) CXINC, cx = &cxstack[cxstack_ix],            \
267         cx->cx_type             = t,                                    \
268         cx->blk_oldsp           = sp - PL_stack_base,                   \
269         cx->blk_oldcop          = PL_curcop,                            \
270         cx->blk_oldmarksp       = PL_markstack_ptr - PL_markstack,      \
271         cx->blk_oldscopesp      = PL_scopestack_ix,                     \
272         cx->blk_oldretsp        = PL_retstack_ix,                       \
273         cx->blk_oldpm           = PL_curpm,                             \
274         cx->blk_gimme           = gimme;                                \
275         DEBUG_l( PerlIO_printf(Perl_debug_log, "Entering block %ld, type %s\n", \
276                     (long)cxstack_ix, PL_block_type[CxTYPE(cx)]); )
277
278 /* Exit a block (RETURN and LAST). */
279 #define POPBLOCK(cx,pm) cx = &cxstack[cxstack_ix--],                    \
280         newsp            = PL_stack_base + cx->blk_oldsp,               \
281         PL_curcop        = cx->blk_oldcop,                              \
282         PL_markstack_ptr = PL_markstack + cx->blk_oldmarksp,            \
283         PL_scopestack_ix = cx->blk_oldscopesp,                          \
284         PL_retstack_ix   = cx->blk_oldretsp,                            \
285         pm               = cx->blk_oldpm,                               \
286         gimme            = cx->blk_gimme;                               \
287         DEBUG_l( PerlIO_printf(Perl_debug_log, "Leaving block %ld, type %s\n",          \
288                     (long)cxstack_ix+1,PL_block_type[CxTYPE(cx)]); )
289
290 /* Continue a block elsewhere (NEXT and REDO). */
291 #define TOPBLOCK(cx) cx  = &cxstack[cxstack_ix],                        \
292         PL_stack_sp      = PL_stack_base + cx->blk_oldsp,               \
293         PL_markstack_ptr = PL_markstack + cx->blk_oldmarksp,            \
294         PL_scopestack_ix = cx->blk_oldscopesp,                          \
295         PL_retstack_ix   = cx->blk_oldretsp,                            \
296         PL_curpm         = cx->blk_oldpm
297
298 /* substitution context */
299 struct subst {
300     I32         sbu_iters;
301     I32         sbu_maxiters;
302     I32         sbu_rflags;
303     I32         sbu_oldsave;
304     bool        sbu_once;
305     bool        sbu_rxtainted;
306     char *      sbu_orig;
307     SV *        sbu_dstr;
308     SV *        sbu_targ;
309     char *      sbu_s;
310     char *      sbu_m;
311     char *      sbu_strend;
312     void *      sbu_rxres;
313     REGEXP *    sbu_rx;
314 };
315 #define sb_iters        cx_u.cx_subst.sbu_iters
316 #define sb_maxiters     cx_u.cx_subst.sbu_maxiters
317 #define sb_rflags       cx_u.cx_subst.sbu_rflags
318 #define sb_oldsave      cx_u.cx_subst.sbu_oldsave
319 #define sb_once         cx_u.cx_subst.sbu_once
320 #define sb_rxtainted    cx_u.cx_subst.sbu_rxtainted
321 #define sb_orig         cx_u.cx_subst.sbu_orig
322 #define sb_dstr         cx_u.cx_subst.sbu_dstr
323 #define sb_targ         cx_u.cx_subst.sbu_targ
324 #define sb_s            cx_u.cx_subst.sbu_s
325 #define sb_m            cx_u.cx_subst.sbu_m
326 #define sb_strend       cx_u.cx_subst.sbu_strend
327 #define sb_rxres        cx_u.cx_subst.sbu_rxres
328 #define sb_rx           cx_u.cx_subst.sbu_rx
329
330 #define PUSHSUBST(cx) CXINC, cx = &cxstack[cxstack_ix],                 \
331         cx->sb_iters            = iters,                                \
332         cx->sb_maxiters         = maxiters,                             \
333         cx->sb_rflags           = r_flags,                              \
334         cx->sb_oldsave          = oldsave,                              \
335         cx->sb_once             = once,                                 \
336         cx->sb_rxtainted        = rxtainted,                            \
337         cx->sb_orig             = orig,                                 \
338         cx->sb_dstr             = dstr,                                 \
339         cx->sb_targ             = targ,                                 \
340         cx->sb_s                = s,                                    \
341         cx->sb_m                = m,                                    \
342         cx->sb_strend           = strend,                               \
343         cx->sb_rxres            = Null(void*),                          \
344         cx->sb_rx               = rx,                                   \
345         cx->cx_type             = CXt_SUBST;                            \
346         rxres_save(&cx->sb_rxres, rx)
347
348 #define POPSUBST(cx) cx = &cxstack[cxstack_ix--];                       \
349         rxres_free(&cx->sb_rxres)
350
351 struct context {
352     U32         cx_type;        /* what kind of context this is */
353     union {
354         struct block    cx_blk;
355         struct subst    cx_subst;
356     } cx_u;
357 };
358
359 #define CXTYPEMASK      0xff
360 #define CXt_NULL        0
361 #define CXt_SUB         1
362 #define CXt_EVAL        2
363 #define CXt_LOOP        3
364 #define CXt_SUBST       4
365 #define CXt_BLOCK       5
366 #define CXt_FORMAT      6
367
368 /* private flags for CXt_EVAL */
369 #define CXp_REAL        0x00000100      /* truly eval'', not a lookalike */
370 #define CXp_TRYBLOCK    0x00000200      /* eval{}, not eval'' or similar */
371
372 #ifdef USE_ITHREADS
373 /* private flags for CXt_LOOP */
374 #  define CXp_PADVAR    0x00000100      /* itervar lives on pad, iterdata
375                                            has pad offset; if not set,
376                                            iterdata holds GV* */
377 #  define CxPADLOOP(c)  (((c)->cx_type & (CXt_LOOP|CXp_PADVAR))         \
378                          == (CXt_LOOP|CXp_PADVAR))
379 #endif
380
381 #define CxTYPE(c)       ((c)->cx_type & CXTYPEMASK)
382 #define CxREALEVAL(c)   (((c)->cx_type & (CXt_EVAL|CXp_REAL))           \
383                          == (CXt_EVAL|CXp_REAL))
384 #define CxTRYBLOCK(c)   (((c)->cx_type & (CXt_EVAL|CXp_TRYBLOCK))       \
385                          == (CXt_EVAL|CXp_TRYBLOCK))
386
387 #define CXINC (cxstack_ix < cxstack_max ? ++cxstack_ix : (cxstack_ix = cxinc()))
388
389 /* "gimme" values */
390
391 /*
392 =for apidoc AmU||G_SCALAR
393 Used to indicate scalar context.  See C<GIMME_V>, C<GIMME>, and
394 L<perlcall>.
395
396 =for apidoc AmU||G_ARRAY
397 Used to indicate list context.  See C<GIMME_V>, C<GIMME> and
398 L<perlcall>.
399
400 =for apidoc AmU||G_VOID
401 Used to indicate void context.  See C<GIMME_V> and L<perlcall>.
402
403 =for apidoc AmU||G_DISCARD
404 Indicates that arguments returned from a callback should be discarded.  See
405 L<perlcall>.
406
407 =for apidoc AmU||G_EVAL
408
409 Used to force a Perl C<eval> wrapper around a callback.  See
410 L<perlcall>.
411
412 =for apidoc AmU||G_NOARGS
413
414 Indicates that no arguments are being sent to a callback.  See
415 L<perlcall>.
416
417 =cut
418 */
419
420 #define G_SCALAR        0
421 #define G_ARRAY         1
422 #define G_VOID          128     /* skip this bit when adding flags below */
423
424 /* extra flags for Perl_call_* routines */
425 #define G_DISCARD       2       /* Call FREETMPS. */
426 #define G_EVAL          4       /* Assume eval {} around subroutine call. */
427 #define G_NOARGS        8       /* Don't construct a @_ array. */
428 #define G_KEEPERR      16       /* Append errors to $@, don't overwrite it */
429 #define G_NODEBUG      32       /* Disable debugging at toplevel.  */
430 #define G_METHOD       64       /* Calling method. */
431
432 /* flag bits for PL_in_eval */
433 #define EVAL_NULL       0       /* not in an eval */
434 #define EVAL_INEVAL     1       /* some enclosing scope is an eval */
435 #define EVAL_WARNONLY   2       /* used by yywarn() when calling yyerror() */
436 #define EVAL_KEEPERR    4       /* set by Perl_call_sv if G_KEEPERR */
437 #define EVAL_INREQUIRE  8       /* The code is being required. */
438
439 /* Support for switching (stack and block) contexts.
440  * This ensures magic doesn't invalidate local stack and cx pointers.
441  */
442
443 #define PERLSI_UNKNOWN          -1
444 #define PERLSI_UNDEF            0
445 #define PERLSI_MAIN             1
446 #define PERLSI_MAGIC            2
447 #define PERLSI_SORT             3
448 #define PERLSI_SIGNAL           4
449 #define PERLSI_OVERLOAD         5
450 #define PERLSI_DESTROY          6
451 #define PERLSI_WARNHOOK         7
452 #define PERLSI_DIEHOOK          8
453 #define PERLSI_REQUIRE          9
454
455 struct stackinfo {
456     AV *                si_stack;       /* stack for current runlevel */
457     PERL_CONTEXT *      si_cxstack;     /* context stack for runlevel */
458     I32                 si_cxix;        /* current context index */
459     I32                 si_cxmax;       /* maximum allocated index */
460     I32                 si_type;        /* type of runlevel */
461     struct stackinfo *  si_prev;
462     struct stackinfo *  si_next;
463     I32                 si_markoff;     /* offset where markstack begins for us.
464                                          * currently used only with DEBUGGING,
465                                          * but not #ifdef-ed for bincompat */
466 };
467
468 typedef struct stackinfo PERL_SI;
469
470 #define cxstack         (PL_curstackinfo->si_cxstack)
471 #define cxstack_ix      (PL_curstackinfo->si_cxix)
472 #define cxstack_max     (PL_curstackinfo->si_cxmax)
473
474 #ifdef DEBUGGING
475 #  define       SET_MARK_OFFSET \
476     PL_curstackinfo->si_markoff = PL_markstack_ptr - PL_markstack
477 #else
478 #  define       SET_MARK_OFFSET NOOP
479 #endif
480
481 #define PUSHSTACKi(type) \
482     STMT_START {                                                        \
483         PERL_SI *next = PL_curstackinfo->si_next;                       \
484         if (!next) {                                                    \
485             next = new_stackinfo(32, 2048/sizeof(PERL_CONTEXT) - 1);    \
486             next->si_prev = PL_curstackinfo;                            \
487             PL_curstackinfo->si_next = next;                            \
488         }                                                               \
489         next->si_type = type;                                           \
490         next->si_cxix = -1;                                             \
491         AvFILLp(next->si_stack) = 0;                                    \
492         SWITCHSTACK(PL_curstack,next->si_stack);                        \
493         PL_curstackinfo = next;                                         \
494         SET_MARK_OFFSET;                                                \
495     } STMT_END
496
497 #define PUSHSTACK PUSHSTACKi(PERLSI_UNKNOWN)
498
499 /* POPSTACK works with PL_stack_sp, so it may need to be bracketed by
500  * PUTBACK/SPAGAIN to flush/refresh any local SP that may be active */
501 #define POPSTACK \
502     STMT_START {                                                        \
503         djSP;                                                           \
504         PERL_SI *prev = PL_curstackinfo->si_prev;                       \
505         if (!prev) {                                                    \
506             PerlIO_printf(Perl_error_log, "panic: POPSTACK\n");         \
507             my_exit(1);                                                 \
508         }                                                               \
509         SWITCHSTACK(PL_curstack,prev->si_stack);                        \
510         /* don't free prev here, free them all at the END{} */          \
511         PL_curstackinfo = prev;                                         \
512     } STMT_END
513
514 #define POPSTACK_TO(s) \
515     STMT_START {                                                        \
516         while (PL_curstack != s) {                                      \
517             dounwind(-1);                                               \
518             POPSTACK;                                                   \
519         }                                                               \
520     } STMT_END