cop.h

   1 /*    cop.h
   2  *
   3  *    Copyright (c) 1991-2002, 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  * Control ops (cops) are one of the three ops OP_NEXTSTATE, OP_DBSTATE,
   9  * and OP_SETSTATE that (loosely speaking) separate statements. They hold
  10  * imformation important for lexical state and error reporting. At run
  11  * time, PL_curcop is set to point to the most recently executed cop,
  12  * and thus can be used to determine our current state.
  13  */
  14
  15 struct cop {
  16     BASEOP
  17     char *      cop_label;      /* label for this construct */
  18 #ifdef USE_ITHREADS
  19     char *      cop_stashpv;    /* package line was compiled in */
  20     char *      cop_file;       /* file name the following line # is from */
  21 #else
  22     HV *        cop_stash;      /* package line was compiled in */
  23     GV *        cop_filegv;     /* file the following line # is from */
  24 #endif
  25     U32         cop_seq;        /* parse sequence number */
  26     I32         cop_arybase;    /* array base this line was compiled with */
  27     line_t      cop_line;       /* line # of this command */
  28     SV *        cop_warnings;   /* lexical warnings bitmask */
  29     SV *        cop_io;         /* lexical IO defaults */
  30 };
  31
  32 #define Nullcop Null(COP*)
  33
  34 #ifdef USE_ITHREADS
  35 #  define CopFILE(c)            ((c)->cop_file)
  36 #  define CopFILEGV(c)          (CopFILE(c) \
  37                                  ? gv_fetchfile(CopFILE(c)) : Nullgv)
  38
  39  #ifdef NETWARE
  40   #define CopFILE_set(c,pv)     ((c)->cop_file = savepv(pv))
  41  #else
  42   #define CopFILE_set(c,pv)     ((c)->cop_file = savesharedpv(pv))
  43  #endif
  44
  45 #  define CopFILESV(c)          (CopFILE(c) \
  46                                  ? GvSV(gv_fetchfile(CopFILE(c))) : Nullsv)
  47 #  define CopFILEAV(c)          (CopFILE(c) \
  48                                  ? GvAV(gv_fetchfile(CopFILE(c))) : Nullav)
  49 #  define CopSTASHPV(c)         ((c)->cop_stashpv)
  50
  51   #ifdef NETWARE
  52     #define CopSTASHPV_set(c,pv)        ((c)->cop_stashpv = ((pv) ? savepv(pv) : Nullch))
  53   #else
  54     #define CopSTASHPV_set(c,pv)        ((c)->cop_stashpv = savesharedpv(pv))
  55   #endif
  56
  57 #  define CopSTASH(c)           (CopSTASHPV(c) \
  58                                  ? gv_stashpv(CopSTASHPV(c),GV_ADD) : Nullhv)
  59 #  define CopSTASH_set(c,hv)    CopSTASHPV_set(c, (hv) ? HvNAME(hv) : Nullch)
  60 #  define CopSTASH_eq(c,hv)     ((hv)                                   \
  61                                  && (CopSTASHPV(c) == HvNAME(hv)        \
  62                                      || (CopSTASHPV(c) && HvNAME(hv)    \
  63                                          && strEQ(CopSTASHPV(c), HvNAME(hv)))))
  64   #ifdef NETWARE
  65     #define CopSTASH_free(c) SAVECOPSTASH_FREE(c)
  66   #else
  67     #define CopSTASH_free(c)    PerlMemShared_free(CopSTASHPV(c))
  68   #endif
  69
  70   #ifdef NETWARE
  71     #define CopFILE_free(c) SAVECOPFILE_FREE(c)
  72   #else
  73     #define CopFILE_free(c)     (PerlMemShared_free(CopFILE(c)),(CopFILE(c) = Nullch))
  74   #endif
  75 #else
  76 #  define CopFILEGV(c)          ((c)->cop_filegv)
  77 #  define CopFILEGV_set(c,gv)   ((c)->cop_filegv = (GV*)SvREFCNT_inc(gv))
  78 #  define CopFILE_set(c,pv)     CopFILEGV_set((c), gv_fetchfile(pv))
  79 #  define CopFILESV(c)          (CopFILEGV(c) ? GvSV(CopFILEGV(c)) : Nullsv)
  80 #  define CopFILEAV(c)          (CopFILEGV(c) ? GvAV(CopFILEGV(c)) : Nullav)
  81 #  define CopFILE(c)            (CopFILESV(c) ? SvPVX(CopFILESV(c)) : Nullch)
  82 #  define CopSTASH(c)           ((c)->cop_stash)
  83 #  define CopSTASH_set(c,hv)    ((c)->cop_stash = (hv))
  84 #  define CopSTASHPV(c)         (CopSTASH(c) ? HvNAME(CopSTASH(c)) : Nullch)
  85    /* cop_stash is not refcounted */
  86 #  define CopSTASHPV_set(c,pv)  CopSTASH_set((c), gv_stashpv(pv,GV_ADD))
  87 #  define CopSTASH_eq(c,hv)     (CopSTASH(c) == (hv))
  88 #  define CopSTASH_free(c)
  89 #  define CopFILE_free(c)       (SvREFCNT_dec(CopFILEGV(c)),(CopFILEGV(c) = Nullgv))
  90
  91 #endif /* USE_ITHREADS */
  92
  93 #define CopSTASH_ne(c,hv)       (!CopSTASH_eq(c,hv))
  94 #define CopLINE(c)              ((c)->cop_line)
  95 #define CopLINE_inc(c)          (++CopLINE(c))
  96 #define CopLINE_dec(c)          (--CopLINE(c))
  97 #define CopLINE_set(c,l)        (CopLINE(c) = (l))
  98
  99 /* OutCopFILE() is CopFILE for output (caller, die, warn, etc.) */
 100 #ifdef MACOS_TRADITIONAL
 101 #  define OutCopFILE(c) MacPerl_MPWFileName(CopFILE(c))
 102 #else
 103 #  define OutCopFILE(c) CopFILE(c)
 104 #endif
 105
 106 /*
 107  * Here we have some enormously heavy (or at least ponderous) wizardry.
 108  */
 109
 110 /* subroutine context */
 111 struct block_sub {
 112     CV *        cv;
 113     GV *        gv;
 114     GV *        dfoutgv;
 115     AV *        savearray;
 116     AV *        argarray;
 117     long        olddepth;
 118     U8          hasargs;
 119     U8          lval;           /* XXX merge lval and hasargs? */
 120     PAD         *oldcomppad;
 121 };
 122
 123 #define PUSHSUB(cx)                                                     \
 124         cx->blk_sub.cv = cv;                                            \
 125         cx->blk_sub.olddepth = CvDEPTH(cv);                             \
 126         cx->blk_sub.hasargs = hasargs;                                  \
 127         cx->blk_sub.lval = PL_op->op_private &                          \
 128                               (OPpLVAL_INTRO|OPpENTERSUB_INARGS);
 129
 130 #define PUSHFORMAT(cx)                                                  \
 131         cx->blk_sub.cv = cv;                                            \
 132         cx->blk_sub.gv = gv;                                            \
 133         cx->blk_sub.hasargs = 0;                                        \
 134         cx->blk_sub.dfoutgv = PL_defoutgv;                              \
 135         (void)SvREFCNT_inc(cx->blk_sub.dfoutgv)
 136
 137 #define POP_SAVEARRAY()                                         \
 138     STMT_START {                                                        \
 139         SvREFCNT_dec(GvAV(PL_defgv));                                   \
 140         GvAV(PL_defgv) = cx->blk_sub.savearray;                         \
 141     } STMT_END
 142
 143 /* junk in @_ spells trouble when cloning CVs and in pp_caller(), so don't
 144  * leave any (a fast av_clear(ary), basically) */
 145 #define CLEAR_ARGARRAY(ary) \
 146     STMT_START {                                                        \
 147         AvMAX(ary) += AvARRAY(ary) - AvALLOC(ary);                      \
 148         SvPVX(ary) = (char*)AvALLOC(ary);                               \
 149         AvFILLp(ary) = -1;                                              \
 150     } STMT_END
 151
 152 #define POPSUB(cx,sv)                                                   \
 153     STMT_START {                                                        \
 154         if (cx->blk_sub.hasargs) {                                      \
 155             POP_SAVEARRAY();                                            \
 156             /* abandon @_ if it got reified */                          \
 157             if (AvREAL(cx->blk_sub.argarray)) {                         \
 158                 SSize_t fill = AvFILLp(cx->blk_sub.argarray);           \
 159                 SvREFCNT_dec(cx->blk_sub.argarray);                     \
 160                 cx->blk_sub.argarray = newAV();                         \
 161                 av_extend(cx->blk_sub.argarray, fill);                  \
 162                 AvFLAGS(cx->blk_sub.argarray) = AVf_REIFY;              \
 163                 CX_CURPAD_SV(cx->blk_sub, 0) = (SV*)cx->blk_sub.argarray;       \
 164             }                                                           \
 165             else {                                                      \
 166                 CLEAR_ARGARRAY(cx->blk_sub.argarray);                   \
 167             }                                                           \
 168         }                                                               \
 169         sv = (SV*)cx->blk_sub.cv;                                       \
 170         if (sv && (CvDEPTH((CV*)sv) = cx->blk_sub.olddepth))            \
 171             sv = Nullsv;                                                \
 172     } STMT_END
 173
 174 #define LEAVESUB(sv)                                                    \
 175     STMT_START {                                                        \
 176         if (sv)                                                         \
 177             SvREFCNT_dec(sv);                                           \
 178     } STMT_END
 179
 180 #define POPFORMAT(cx)                                                   \
 181         setdefout(cx->blk_sub.dfoutgv);                                 \
 182         SvREFCNT_dec(cx->blk_sub.dfoutgv);
 183
 184 /* eval context */
 185 struct block_eval {
 186     I32         old_in_eval;
 187     I32         old_op_type;
 188     SV *        old_namesv;
 189     OP *        old_eval_root;
 190     SV *        cur_text;
 191     CV *        cv;
 192 };
 193
 194 #define PUSHEVAL(cx,n,fgv)                                              \
 195     STMT_START {                                                        \
 196         cx->blk_eval.old_in_eval = PL_in_eval;                          \
 197         cx->blk_eval.old_op_type = PL_op->op_type;                      \
 198         cx->blk_eval.old_namesv = (n ? newSVpv(n,0) : Nullsv);          \
 199         cx->blk_eval.old_eval_root = PL_eval_root;                      \
 200         cx->blk_eval.cur_text = PL_linestr;                             \
 201         cx->blk_eval.cv = Nullcv; /* set by doeval(), as applicable */  \
 202     } STMT_END
 203
 204 #define POPEVAL(cx)                                                     \
 205     STMT_START {                                                        \
 206         PL_in_eval = cx->blk_eval.old_in_eval;                          \
 207         optype = cx->blk_eval.old_op_type;                              \
 208         PL_eval_root = cx->blk_eval.old_eval_root;                      \
 209         if (cx->blk_eval.old_namesv)                                    \
 210             sv_2mortal(cx->blk_eval.old_namesv);                        \
 211     } STMT_END
 212
 213 /* loop context */
 214 struct block_loop {
 215     char *      label;
 216     I32         resetsp;
 217     OP *        redo_op;
 218     OP *        next_op;
 219     OP *        last_op;
 220 #ifdef USE_ITHREADS
 221     void *      iterdata;
 222     PAD         *oldcomppad;
 223 #else
 224     SV **       itervar;
 225 #endif
 226     SV *        itersave;
 227     SV *        iterlval;
 228     AV *        iterary;
 229     IV          iterix;
 230     IV          itermax;
 231 };
 232
 233 #ifdef USE_ITHREADS
 234 #  define CxITERVAR(c)                                                  \
 235         ((c)->blk_loop.iterdata                                         \
 236          ? (CxPADLOOP(cx)                                               \
 237             ? &CX_CURPAD_SV( (c)->blk_loop,                             \
 238                     INT2PTR(PADOFFSET, (c)->blk_loop.iterdata))         \
 239             : &GvSV((GV*)(c)->blk_loop.iterdata))                       \
 240          : (SV**)NULL)
 241 #  define CX_ITERDATA_SET(cx,idata)                                     \
 242         CX_CURPAD_SAVE(cx->blk_loop);                                   \
 243         if ((cx->blk_loop.iterdata = (idata)))                          \
 244             cx->blk_loop.itersave = SvREFCNT_inc(*CxITERVAR(cx));       \
 245         else                                                            \
 246             cx->blk_loop.itersave = Nullsv;
 247 #else
 248 #  define CxITERVAR(c)          ((c)->blk_loop.itervar)
 249 #  define CX_ITERDATA_SET(cx,ivar)                                      \
 250         if ((cx->blk_loop.itervar = (SV**)(ivar)))                      \
 251             cx->blk_loop.itersave = SvREFCNT_inc(*CxITERVAR(cx));       \
 252         else                                                            \
 253             cx->blk_loop.itersave = Nullsv;
 254 #endif
 255
 256 #define PUSHLOOP(cx, dat, s)                                            \
 257         cx->blk_loop.label = PL_curcop->cop_label;                      \
 258         cx->blk_loop.resetsp = s - PL_stack_base;                       \
 259         cx->blk_loop.redo_op = cLOOP->op_redoop;                        \
 260         cx->blk_loop.next_op = cLOOP->op_nextop;                        \
 261         cx->blk_loop.last_op = cLOOP->op_lastop;                        \
 262         cx->blk_loop.iterlval = Nullsv;                                 \
 263         cx->blk_loop.iterary = Nullav;                                  \
 264         cx->blk_loop.iterix = -1;                                       \
 265         CX_ITERDATA_SET(cx,dat);
 266
 267 #define POPLOOP(cx)                                                     \
 268         SvREFCNT_dec(cx->blk_loop.iterlval);                            \
 269         if (CxITERVAR(cx)) {                                            \
 270             SV **s_v_p = CxITERVAR(cx);                                 \
 271             sv_2mortal(*s_v_p);                                         \
 272             *s_v_p = cx->blk_loop.itersave;                             \
 273         }                                                               \
 274         if (cx->blk_loop.iterary && cx->blk_loop.iterary != PL_curstack)\
 275             SvREFCNT_dec(cx->blk_loop.iterary);
 276
 277 /* context common to subroutines, evals and loops */
 278 struct block {
 279     I32         blku_oldsp;     /* stack pointer to copy stuff down to */
 280     COP *       blku_oldcop;    /* old curcop pointer */
 281     I32         blku_oldretsp;  /* return stack index */
 282     I32         blku_oldmarksp; /* mark stack index */
 283     I32         blku_oldscopesp;        /* scope stack index */
 284     PMOP *      blku_oldpm;     /* values of pattern match vars */
 285     U8          blku_gimme;     /* is this block running in list context? */
 286
 287     union {
 288         struct block_sub        blku_sub;
 289         struct block_eval       blku_eval;
 290         struct block_loop       blku_loop;
 291     } blk_u;
 292 };
 293 #define blk_oldsp       cx_u.cx_blk.blku_oldsp
 294 #define blk_oldcop      cx_u.cx_blk.blku_oldcop
 295 #define blk_oldretsp    cx_u.cx_blk.blku_oldretsp
 296 #define blk_oldmarksp   cx_u.cx_blk.blku_oldmarksp
 297 #define blk_oldscopesp  cx_u.cx_blk.blku_oldscopesp
 298 #define blk_oldpm       cx_u.cx_blk.blku_oldpm
 299 #define blk_gimme       cx_u.cx_blk.blku_gimme
 300 #define blk_sub         cx_u.cx_blk.blk_u.blku_sub
 301 #define blk_eval        cx_u.cx_blk.blk_u.blku_eval
 302 #define blk_loop        cx_u.cx_blk.blk_u.blku_loop
 303
 304 /* Enter a block. */
 305 #define PUSHBLOCK(cx,t,sp) CXINC, cx = &cxstack[cxstack_ix],            \
 306         cx->cx_type             = t,                                    \
 307         cx->blk_oldsp           = sp - PL_stack_base,                   \
 308         cx->blk_oldcop          = PL_curcop,                            \
 309         cx->blk_oldmarksp       = PL_markstack_ptr - PL_markstack,      \
 310         cx->blk_oldscopesp      = PL_scopestack_ix,                     \
 311         cx->blk_oldretsp        = PL_retstack_ix,                       \
 312         cx->blk_oldpm           = PL_curpm,                             \
 313         cx->blk_gimme           = (U8)gimme;                            \
 314         DEBUG_l( PerlIO_printf(Perl_debug_log, "Entering block %ld, type %s\n", \
 315                     (long)cxstack_ix, PL_block_type[CxTYPE(cx)]); )
 316
 317 /* Exit a block (RETURN and LAST). */
 318 #define POPBLOCK(cx,pm) cx = &cxstack[cxstack_ix--],                    \
 319         newsp            = PL_stack_base + cx->blk_oldsp,               \
 320         PL_curcop        = cx->blk_oldcop,                              \
 321         PL_markstack_ptr = PL_markstack + cx->blk_oldmarksp,            \
 322         PL_scopestack_ix = cx->blk_oldscopesp,                          \
 323         PL_retstack_ix   = cx->blk_oldretsp,                            \
 324         pm               = cx->blk_oldpm,                               \
 325         gimme            = cx->blk_gimme;                               \
 326         DEBUG_l( PerlIO_printf(Perl_debug_log, "Leaving block %ld, type %s\n",          \
 327                     (long)cxstack_ix+1,PL_block_type[CxTYPE(cx)]); )
 328
 329 /* Continue a block elsewhere (NEXT and REDO). */
 330 #define TOPBLOCK(cx) cx  = &cxstack[cxstack_ix],                        \
 331         PL_stack_sp      = PL_stack_base + cx->blk_oldsp,               \
 332         PL_markstack_ptr = PL_markstack + cx->blk_oldmarksp,            \
 333         PL_scopestack_ix = cx->blk_oldscopesp,                          \
 334         PL_retstack_ix   = cx->blk_oldretsp,                            \
 335         PL_curpm         = cx->blk_oldpm
 336
 337 /* substitution context */
 338 struct subst {
 339     I32         sbu_iters;
 340     I32         sbu_maxiters;
 341     I32         sbu_rflags;
 342     I32         sbu_oldsave;
 343     bool        sbu_once;
 344     bool        sbu_rxtainted;
 345     char *      sbu_orig;
 346     SV *        sbu_dstr;
 347     SV *        sbu_targ;
 348     char *      sbu_s;
 349     char *      sbu_m;
 350     char *      sbu_strend;
 351     void *      sbu_rxres;
 352     REGEXP *    sbu_rx;
 353 };
 354 #define sb_iters        cx_u.cx_subst.sbu_iters
 355 #define sb_maxiters     cx_u.cx_subst.sbu_maxiters
 356 #define sb_rflags       cx_u.cx_subst.sbu_rflags
 357 #define sb_oldsave      cx_u.cx_subst.sbu_oldsave
 358 #define sb_once         cx_u.cx_subst.sbu_once
 359 #define sb_rxtainted    cx_u.cx_subst.sbu_rxtainted
 360 #define sb_orig         cx_u.cx_subst.sbu_orig
 361 #define sb_dstr         cx_u.cx_subst.sbu_dstr
 362 #define sb_targ         cx_u.cx_subst.sbu_targ
 363 #define sb_s            cx_u.cx_subst.sbu_s
 364 #define sb_m            cx_u.cx_subst.sbu_m
 365 #define sb_strend       cx_u.cx_subst.sbu_strend
 366 #define sb_rxres        cx_u.cx_subst.sbu_rxres
 367 #define sb_rx           cx_u.cx_subst.sbu_rx
 368
 369 #define PUSHSUBST(cx) CXINC, cx = &cxstack[cxstack_ix],                 \
 370         cx->sb_iters            = iters,                                \
 371         cx->sb_maxiters         = maxiters,                             \
 372         cx->sb_rflags           = r_flags,                              \
 373         cx->sb_oldsave          = oldsave,                              \
 374         cx->sb_once             = once,                                 \
 375         cx->sb_rxtainted        = rxtainted,                            \
 376         cx->sb_orig             = orig,                                 \
 377         cx->sb_dstr             = dstr,                                 \
 378         cx->sb_targ             = targ,                                 \
 379         cx->sb_s                = s,                                    \
 380         cx->sb_m                = m,                                    \
 381         cx->sb_strend           = strend,                               \
 382         cx->sb_rxres            = Null(void*),                          \
 383         cx->sb_rx               = rx,                                   \
 384         cx->cx_type             = CXt_SUBST;                            \
 385         rxres_save(&cx->sb_rxres, rx)
 386
 387 #define POPSUBST(cx) cx = &cxstack[cxstack_ix--];                       \
 388         rxres_free(&cx->sb_rxres)
 389
 390 struct context {
 391     U32         cx_type;        /* what kind of context this is */
 392     union {
 393         struct block    cx_blk;
 394         struct subst    cx_subst;
 395     } cx_u;
 396 };
 397
 398 #define CXTYPEMASK      0xff
 399 #define CXt_NULL        0
 400 #define CXt_SUB         1
 401 #define CXt_EVAL        2
 402 #define CXt_LOOP        3
 403 #define CXt_SUBST       4
 404 #define CXt_BLOCK       5
 405 #define CXt_FORMAT      6
 406
 407 /* private flags for CXt_EVAL */
 408 #define CXp_REAL        0x00000100      /* truly eval'', not a lookalike */
 409 #define CXp_TRYBLOCK    0x00000200      /* eval{}, not eval'' or similar */
 410
 411 #ifdef USE_ITHREADS
 412 /* private flags for CXt_LOOP */
 413 #  define CXp_PADVAR    0x00000100      /* itervar lives on pad, iterdata
 414                                            has pad offset; if not set,
 415                                            iterdata holds GV* */
 416 #  define CxPADLOOP(c)  (((c)->cx_type & (CXt_LOOP|CXp_PADVAR))         \
 417                          == (CXt_LOOP|CXp_PADVAR))
 418 #endif
 419
 420 #define CxTYPE(c)       ((c)->cx_type & CXTYPEMASK)
 421 #define CxREALEVAL(c)   (((c)->cx_type & (CXt_EVAL|CXp_REAL))           \
 422                          == (CXt_EVAL|CXp_REAL))
 423 #define CxTRYBLOCK(c)   (((c)->cx_type & (CXt_EVAL|CXp_TRYBLOCK))       \
 424                          == (CXt_EVAL|CXp_TRYBLOCK))
 425
 426 #define CXINC (cxstack_ix < cxstack_max ? ++cxstack_ix : (cxstack_ix = cxinc()))
 427
 428 /*
 429 =head1 "Gimme" Values
 430 */
 431
 432 /*
 433 =for apidoc AmU||G_SCALAR
 434 Used to indicate scalar context.  See C<GIMME_V>, C<GIMME>, and
 435 L<perlcall>.
 436
 437 =for apidoc AmU||G_ARRAY
 438 Used to indicate list context.  See C<GIMME_V>, C<GIMME> and
 439 L<perlcall>.
 440
 441 =for apidoc AmU||G_VOID
 442 Used to indicate void context.  See C<GIMME_V> and L<perlcall>.
 443
 444 =for apidoc AmU||G_DISCARD
 445 Indicates that arguments returned from a callback should be discarded.  See
 446 L<perlcall>.
 447
 448 =for apidoc AmU||G_EVAL
 449
 450 Used to force a Perl C<eval> wrapper around a callback.  See
 451 L<perlcall>.
 452
 453 =for apidoc AmU||G_NOARGS
 454
 455 Indicates that no arguments are being sent to a callback.  See
 456 L<perlcall>.
 457
 458 =cut
 459 */
 460
 461 #define G_SCALAR        0
 462 #define G_ARRAY         1
 463 #define G_VOID          128     /* skip this bit when adding flags below */
 464
 465 /* extra flags for Perl_call_* routines */
 466 #define G_DISCARD       2       /* Call FREETMPS. */
 467 #define G_EVAL          4       /* Assume eval {} around subroutine call. */
 468 #define G_NOARGS        8       /* Don't construct a @_ array. */
 469 #define G_KEEPERR      16       /* Append errors to $@, don't overwrite it */
 470 #define G_NODEBUG      32       /* Disable debugging at toplevel.  */
 471 #define G_METHOD       64       /* Calling method. */
 472
 473 /* flag bits for PL_in_eval */
 474 #define EVAL_NULL       0       /* not in an eval */
 475 #define EVAL_INEVAL     1       /* some enclosing scope is an eval */
 476 #define EVAL_WARNONLY   2       /* used by yywarn() when calling yyerror() */
 477 #define EVAL_KEEPERR    4       /* set by Perl_call_sv if G_KEEPERR */
 478 #define EVAL_INREQUIRE  8       /* The code is being required. */
 479
 480 /* Support for switching (stack and block) contexts.
 481  * This ensures magic doesn't invalidate local stack and cx pointers.
 482  */
 483
 484 #define PERLSI_UNKNOWN          -1
 485 #define PERLSI_UNDEF            0
 486 #define PERLSI_MAIN             1
 487 #define PERLSI_MAGIC            2
 488 #define PERLSI_SORT             3
 489 #define PERLSI_SIGNAL           4
 490 #define PERLSI_OVERLOAD         5
 491 #define PERLSI_DESTROY          6
 492 #define PERLSI_WARNHOOK         7
 493 #define PERLSI_DIEHOOK          8
 494 #define PERLSI_REQUIRE          9
 495
 496 struct stackinfo {
 497     AV *                si_stack;       /* stack for current runlevel */
 498     PERL_CONTEXT *      si_cxstack;     /* context stack for runlevel */
 499     I32                 si_cxix;        /* current context index */
 500     I32                 si_cxmax;       /* maximum allocated index */
 501     I32                 si_type;        /* type of runlevel */
 502     struct stackinfo *  si_prev;
 503     struct stackinfo *  si_next;
 504     I32                 si_markoff;     /* offset where markstack begins for us.
 505                                          * currently used only with DEBUGGING,
 506                                          * but not #ifdef-ed for bincompat */
 507 };
 508
 509 typedef struct stackinfo PERL_SI;
 510
 511 #define cxstack         (PL_curstackinfo->si_cxstack)
 512 #define cxstack_ix      (PL_curstackinfo->si_cxix)
 513 #define cxstack_max     (PL_curstackinfo->si_cxmax)
 514
 515 #ifdef DEBUGGING
 516 #  define       SET_MARK_OFFSET \
 517     PL_curstackinfo->si_markoff = PL_markstack_ptr - PL_markstack
 518 #else
 519 #  define       SET_MARK_OFFSET NOOP
 520 #endif
 521
 522 #define PUSHSTACKi(type) \
 523     STMT_START {                                                        \
 524         PERL_SI *next = PL_curstackinfo->si_next;                       \
 525         if (!next) {                                                    \
 526             next = new_stackinfo(32, 2048/sizeof(PERL_CONTEXT) - 1);    \
 527             next->si_prev = PL_curstackinfo;                            \
 528             PL_curstackinfo->si_next = next;                            \
 529         }                                                               \
 530         next->si_type = type;                                           \
 531         next->si_cxix = -1;                                             \
 532         AvFILLp(next->si_stack) = 0;                                    \
 533         SWITCHSTACK(PL_curstack,next->si_stack);                        \
 534         PL_curstackinfo = next;                                         \
 535         SET_MARK_OFFSET;                                                \
 536     } STMT_END
 537
 538 #define PUSHSTACK PUSHSTACKi(PERLSI_UNKNOWN)
 539
 540 /* POPSTACK works with PL_stack_sp, so it may need to be bracketed by
 541  * PUTBACK/SPAGAIN to flush/refresh any local SP that may be active */
 542 #define POPSTACK \
 543     STMT_START {                                                        \
 544         dSP;                                                            \
 545         PERL_SI *prev = PL_curstackinfo->si_prev;                       \
 546         if (!prev) {                                                    \
 547             PerlIO_printf(Perl_error_log, "panic: POPSTACK\n");         \
 548             my_exit(1);                                                 \
 549         }                                                               \
 550         SWITCHSTACK(PL_curstack,prev->si_stack);                        \
 551         /* don't free prev here, free them all at the END{} */          \
 552         PL_curstackinfo = prev;                                         \
 553     } STMT_END
 554
 555 #define POPSTACK_TO(s) \
 556     STMT_START {                                                        \
 557         while (PL_curstack != s) {                                      \
 558             dounwind(-1);                                               \
 559             POPSTACK;                                                   \
 560         }                                                               \
 561     } STMT_END