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