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