cop.h

   1 /*    cop.h
   2  *
   3  *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
   4  *    2000, 2001, 2002, 2003, 2004, by Larry Wall and others
   5  *
   6  *    You may distribute under the terms of either the GNU General Public
   7  *    License or the Artistic License, as specified in the README file.
   8  *
   9  * Control ops (cops) are one of the three ops OP_NEXTSTATE, OP_DBSTATE,
  10  * and OP_SETSTATE that (loosely speaking) are separate statements.
  11  * They hold information important for lexical state and error reporting.
  12  * At run time, PL_curcop is set to point to the most recently executed cop,
  13  * and thus can be used to determine our current state.
  14  */
  15
  16 /* A jmpenv packages the state required to perform a proper non-local jump.
  17  * Note that there is a start_env initialized when perl starts, and top_env
  18  * points to this initially, so top_env should always be non-null.
  19  *
  20  * Existence of a non-null top_env->je_prev implies it is valid to call
  21  * longjmp() at that runlevel (we make sure start_env.je_prev is always
  22  * null to ensure this).
  23  *
  24  * je_mustcatch, when set at any runlevel to TRUE, means eval ops must
  25  * establish a local jmpenv to handle exception traps.  Care must be taken
  26  * to restore the previous value of je_mustcatch before exiting the
  27  * stack frame iff JMPENV_PUSH was not called in that stack frame.
  28  * GSAR 97-03-27
  29  */
  30
  31 struct jmpenv {
  32     struct jmpenv *     je_prev;
  33     Sigjmp_buf          je_buf;         /* only for use if !je_throw */
  34     int                 je_ret;         /* last exception thrown */
  35     bool                je_mustcatch;   /* need to call longjmp()? */
  36 };
  37
  38 typedef struct jmpenv JMPENV;
  39
  40 #ifdef OP_IN_REGISTER
  41 #define OP_REG_TO_MEM   PL_opsave = op
  42 #define OP_MEM_TO_REG   op = PL_opsave
  43 #else
  44 #define OP_REG_TO_MEM   NOOP
  45 #define OP_MEM_TO_REG   NOOP
  46 #endif
  47
  48 /*
  49  * How to build the first jmpenv.
  50  *
  51  * top_env needs to be non-zero. It points to an area
  52  * in which longjmp() stuff is stored, as C callstack
  53  * info there at least is thread specific this has to
  54  * be per-thread. Otherwise a 'die' in a thread gives
  55  * that thread the C stack of last thread to do an eval {}!
  56  */
  57
  58 #define JMPENV_BOOTSTRAP \
  59     STMT_START {                                \
  60         Zero(&PL_start_env, 1, JMPENV);         \
  61         PL_start_env.je_ret = -1;               \
  62         PL_start_env.je_mustcatch = TRUE;       \
  63         PL_top_env = &PL_start_env;             \
  64     } STMT_END
  65
  66 /*
  67  *   PERL_FLEXIBLE_EXCEPTIONS
  68  *
  69  * All the flexible exceptions code has been removed.
  70  * See the following threads for details:
  71  *
  72  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2004-07/msg00378.html
  73  *
  74  * Joshua's original patches (which weren't applied) and discussion:
  75  *
  76  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg01396.html
  77  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg01489.html
  78  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg01491.html
  79  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg01608.html
  80  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg02144.html
  81  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg02998.html
  82  *
  83  * Chip's reworked patch and discussion:
  84  *
  85  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1999-03/msg00520.html
  86  *
  87  * The flaw in these patches (which went unnoticed at the time) was
  88  * that they moved some code that could potentially die() out of the
  89  * region protected by the setjmp()s.  This caused exceptions within
  90  * END blocks and such to not be handled by the correct setjmp().
  91  *
  92  * The original patches that introduces flexible exceptions were:
  93  *
  94  *   http://public.activestate.com/cgi-bin/perlbrowse?patch=3386
  95  *   http://public.activestate.com/cgi-bin/perlbrowse?patch=5162
  96  */
  97
  98 #define dJMPENV         JMPENV cur_env
  99
 100 #define JMPENV_PUSH(v) \
 101     STMT_START {                                                        \
 102         DEBUG_l(Perl_deb(aTHX_ "Setting up jumplevel %p, was %p\n",     \
 103                          &cur_env, PL_top_env));                        \
 104         cur_env.je_prev = PL_top_env;                                   \
 105         OP_REG_TO_MEM;                                                  \
 106         cur_env.je_ret = PerlProc_setjmp(cur_env.je_buf, SCOPE_SAVES_SIGNAL_MASK);              \
 107         OP_MEM_TO_REG;                                                  \
 108         PL_top_env = &cur_env;                                          \
 109         cur_env.je_mustcatch = FALSE;                                   \
 110         (v) = cur_env.je_ret;                                           \
 111     } STMT_END
 112
 113 #define JMPENV_POP \
 114     STMT_START {                                                        \
 115         DEBUG_l(Perl_deb(aTHX_ "popping jumplevel was %p, now %p\n",    \
 116                          PL_top_env, cur_env.je_prev));                 \
 117         PL_top_env = cur_env.je_prev;                                   \
 118     } STMT_END
 119
 120 #define JMPENV_JUMP(v) \
 121     STMT_START {                                                \
 122         OP_REG_TO_MEM;                                          \
 123         if (PL_top_env->je_prev)                                \
 124             PerlProc_longjmp(PL_top_env->je_buf, (v));          \
 125         if ((v) == 2)                                           \
 126             PerlProc_exit(STATUS_NATIVE_EXPORT);                \
 127         PerlIO_printf(PerlIO_stderr(), "panic: top_env\n");     \
 128         PerlProc_exit(1);                                       \
 129     } STMT_END
 130
 131 #define CATCH_GET               (PL_top_env->je_mustcatch)
 132 #define CATCH_SET(v)            (PL_top_env->je_mustcatch = (v))
 133
 134
 135
 136 struct cop {
 137     BASEOP
 138     char *      cop_label;      /* label for this construct */
 139 #ifdef USE_ITHREADS
 140     char *      cop_stashpv;    /* package line was compiled in */
 141     char *      cop_file;       /* file name the following line # is from */
 142 #else
 143     HV *        cop_stash;      /* package line was compiled in */
 144     GV *        cop_filegv;     /* file the following line # is from */
 145 #endif
 146     U32         cop_seq;        /* parse sequence number */
 147     I32         cop_arybase;    /* array base this line was compiled with */
 148     line_t      cop_line;       /* line # of this command */
 149     SV *        cop_warnings;   /* lexical warnings bitmask */
 150     SV *        cop_io;         /* lexical IO defaults */
 151 };
 152
 153 #define Nullcop Null(COP*)
 154
 155 #ifdef USE_ITHREADS
 156 #  define CopFILE(c)            ((c)->cop_file)
 157 #  define CopFILEGV(c)          (CopFILE(c) \
 158                                  ? gv_fetchfile(CopFILE(c)) : Nullgv)
 159
 160 #  ifdef NETWARE
 161 #    define CopFILE_set(c,pv)   ((c)->cop_file = savepv(pv))
 162 #  else
 163 #    define CopFILE_set(c,pv)   ((c)->cop_file = savesharedpv(pv))
 164 #  endif
 165
 166 #  define CopFILESV(c)          (CopFILE(c) \
 167                                  ? GvSV(gv_fetchfile(CopFILE(c))) : Nullsv)
 168 #  define CopFILEAV(c)          (CopFILE(c) \
 169                                  ? GvAV(gv_fetchfile(CopFILE(c))) : Nullav)
 170 #  define CopSTASHPV(c)         ((c)->cop_stashpv)
 171
 172 #  ifdef NETWARE
 173 #    define CopSTASHPV_set(c,pv)        ((c)->cop_stashpv = ((pv) ? savepv(pv) : Nullch))
 174 #  else
 175 #    define CopSTASHPV_set(c,pv)        ((c)->cop_stashpv = savesharedpv(pv))
 176 #  endif
 177
 178 #  define CopSTASH(c)           (CopSTASHPV(c) \
 179                                  ? gv_stashpv(CopSTASHPV(c),GV_ADD) : Nullhv)
 180 #  define CopSTASH_set(c,hv)    CopSTASHPV_set(c, (hv) ? HvNAME_get(hv) : Nullch)
 181 #  define CopSTASH_eq(c,hv)     ((hv) && stashpv_hvname_match(c,hv))
 182 #  ifdef NETWARE
 183 #    define CopSTASH_free(c) SAVECOPSTASH_FREE(c)
 184 #    define CopFILE_free(c) SAVECOPFILE_FREE(c)
 185 #  else
 186 #    define CopSTASH_free(c)    PerlMemShared_free(CopSTASHPV(c))
 187 #    define CopFILE_free(c)     (PerlMemShared_free(CopFILE(c)),(CopFILE(c) = Nullch))
 188 #  endif
 189 #else
 190 #  define CopFILEGV(c)          ((c)->cop_filegv)
 191 #  define CopFILEGV_set(c,gv)   ((c)->cop_filegv = (GV*)SvREFCNT_inc(gv))
 192 #  define CopFILE_set(c,pv)     CopFILEGV_set((c), gv_fetchfile(pv))
 193 #  define CopFILESV(c)          (CopFILEGV(c) ? GvSV(CopFILEGV(c)) : Nullsv)
 194 #  define CopFILEAV(c)          (CopFILEGV(c) ? GvAV(CopFILEGV(c)) : Nullav)
 195 #  define CopFILE(c)            (CopFILESV(c) ? SvPVX(CopFILESV(c)) : Nullch)
 196 #  define CopSTASH(c)           ((c)->cop_stash)
 197 #  define CopSTASH_set(c,hv)    ((c)->cop_stash = (hv))
 198 #  define CopSTASHPV(c)         (CopSTASH(c) ? HvNAME_get(CopSTASH(c)) : Nullch)
 199    /* cop_stash is not refcounted */
 200 #  define CopSTASHPV_set(c,pv)  CopSTASH_set((c), gv_stashpv(pv,GV_ADD))
 201 #  define CopSTASH_eq(c,hv)     (CopSTASH(c) == (hv))
 202 #  define CopSTASH_free(c)
 203 #  define CopFILE_free(c)       (SvREFCNT_dec(CopFILEGV(c)),(CopFILEGV(c) = Nullgv))
 204
 205 #endif /* USE_ITHREADS */
 206
 207 #define CopSTASH_ne(c,hv)       (!CopSTASH_eq(c,hv))
 208 #define CopLINE(c)              ((c)->cop_line)
 209 #define CopLINE_inc(c)          (++CopLINE(c))
 210 #define CopLINE_dec(c)          (--CopLINE(c))
 211 #define CopLINE_set(c,l)        (CopLINE(c) = (l))
 212
 213 /* OutCopFILE() is CopFILE for output (caller, die, warn, etc.) */
 214 #ifdef MACOS_TRADITIONAL
 215 #  define OutCopFILE(c) MacPerl_MPWFileName(CopFILE(c))
 216 #else
 217 #  define OutCopFILE(c) CopFILE(c)
 218 #endif
 219
 220 /*
 221  * Here we have some enormously heavy (or at least ponderous) wizardry.
 222  */
 223
 224 /* subroutine context */
 225 struct block_sub {
 226     CV *        cv;
 227     GV *        gv;
 228     GV *        dfoutgv;
 229     AV *        savearray;
 230     AV *        argarray;
 231     long        olddepth;
 232     U8          hasargs;
 233     U8          lval;           /* XXX merge lval and hasargs? */
 234     PAD         *oldcomppad;
 235     OP *        retop;  /* op to execute on exit from sub */
 236 };
 237
 238 /* base for the next two macros. Don't use directly.
 239  * Note that the refcnt of the cv is incremented twice;  The CX one is
 240  * decremented by LEAVESUB, the other by LEAVE. */
 241
 242 #define PUSHSUB_BASE(cx)                                                \
 243         cx->blk_sub.cv = cv;                                            \
 244         cx->blk_sub.olddepth = CvDEPTH(cv);                             \
 245         cx->blk_sub.hasargs = hasargs;                                  \
 246         cx->blk_sub.retop = Nullop;                                             \
 247         if (!CvDEPTH(cv)) {                                             \
 248             (void)SvREFCNT_inc(cv);                                     \
 249             (void)SvREFCNT_inc(cv);                                     \
 250             SAVEFREESV(cv);                                             \
 251         }
 252
 253
 254 #define PUSHSUB(cx)                                                     \
 255         PUSHSUB_BASE(cx)                                                \
 256         cx->blk_sub.lval = PL_op->op_private &                          \
 257                               (OPpLVAL_INTRO|OPpENTERSUB_INARGS);
 258
 259 /* variant for use by OP_DBSTATE, where op_private holds hint bits */
 260 #define PUSHSUB_DB(cx)                                                  \
 261         PUSHSUB_BASE(cx)                                                \
 262         cx->blk_sub.lval = 0;
 263
 264
 265 #define PUSHFORMAT(cx)                                                  \
 266         cx->blk_sub.cv = cv;                                            \
 267         cx->blk_sub.gv = gv;                                            \
 268         cx->blk_sub.retop = Nullop;                                     \
 269         cx->blk_sub.hasargs = 0;                                        \
 270         cx->blk_sub.dfoutgv = PL_defoutgv;                              \
 271         (void)SvREFCNT_inc(cx->blk_sub.dfoutgv)
 272
 273 #define POP_SAVEARRAY()                                         \
 274     STMT_START {                                                        \
 275         SvREFCNT_dec(GvAV(PL_defgv));                                   \
 276         GvAV(PL_defgv) = cx->blk_sub.savearray;                         \
 277     } STMT_END
 278
 279 /* junk in @_ spells trouble when cloning CVs and in pp_caller(), so don't
 280  * leave any (a fast av_clear(ary), basically) */
 281 #define CLEAR_ARGARRAY(ary) \
 282     STMT_START {                                                        \
 283         AvMAX(ary) += AvARRAY(ary) - AvALLOC(ary);                      \
 284         SvPV_set(ary, (char*)AvALLOC(ary));                             \
 285         AvFILLp(ary) = -1;                                              \
 286     } STMT_END
 287
 288 #define POPSUB(cx,sv)                                                   \
 289     STMT_START {                                                        \
 290         if (cx->blk_sub.hasargs) {                                      \
 291             POP_SAVEARRAY();                                            \
 292             /* abandon @_ if it got reified */                          \
 293             if (AvREAL(cx->blk_sub.argarray)) {                         \
 294                 SSize_t fill = AvFILLp(cx->blk_sub.argarray);           \
 295                 SvREFCNT_dec(cx->blk_sub.argarray);                     \
 296                 cx->blk_sub.argarray = newAV();                         \
 297                 av_extend(cx->blk_sub.argarray, fill);                  \
 298                 AvREIFY_only(cx->blk_sub.argarray);                     \
 299                 CX_CURPAD_SV(cx->blk_sub, 0) = (SV*)cx->blk_sub.argarray;       \
 300             }                                                           \
 301             else {                                                      \
 302                 CLEAR_ARGARRAY(cx->blk_sub.argarray);                   \
 303             }                                                           \
 304         }                                                               \
 305         sv = (SV*)cx->blk_sub.cv;                                       \
 306         if (sv && (CvDEPTH((CV*)sv) = cx->blk_sub.olddepth))            \
 307             sv = Nullsv;                                                \
 308     } STMT_END
 309
 310 #define LEAVESUB(sv)                                                    \
 311     STMT_START {                                                        \
 312         if (sv)                                                         \
 313             SvREFCNT_dec(sv);                                           \
 314     } STMT_END
 315
 316 #define POPFORMAT(cx)                                                   \
 317         setdefout(cx->blk_sub.dfoutgv);                                 \
 318         SvREFCNT_dec(cx->blk_sub.dfoutgv);
 319
 320 /* eval context */
 321 struct block_eval {
 322     I32         old_in_eval;
 323     I32         old_op_type;
 324     SV *        old_namesv;
 325     OP *        old_eval_root;
 326     SV *        cur_text;
 327     CV *        cv;
 328     OP *        retop;  /* op to execute on exit from eval */
 329     JMPENV *    cur_top_env; /* value of PL_top_env when eval CX created */
 330 };
 331
 332 #define PUSHEVAL(cx,n,fgv)                                              \
 333     STMT_START {                                                        \
 334         cx->blk_eval.old_in_eval = PL_in_eval;                          \
 335         cx->blk_eval.old_op_type = PL_op->op_type;                      \
 336         cx->blk_eval.old_namesv = (n ? newSVpv(n,0) : Nullsv);          \
 337         cx->blk_eval.old_eval_root = PL_eval_root;                      \
 338         cx->blk_eval.cur_text = PL_linestr;                             \
 339         cx->blk_eval.cv = Nullcv; /* set by doeval(), as applicable */  \
 340         cx->blk_eval.retop = Nullop;                                    \
 341         cx->blk_eval.cur_top_env = PL_top_env;                          \
 342     } STMT_END
 343
 344 #define POPEVAL(cx)                                                     \
 345     STMT_START {                                                        \
 346         PL_in_eval = cx->blk_eval.old_in_eval;                          \
 347         optype = cx->blk_eval.old_op_type;                              \
 348         PL_eval_root = cx->blk_eval.old_eval_root;                      \
 349         if (cx->blk_eval.old_namesv)                                    \
 350             sv_2mortal(cx->blk_eval.old_namesv);                        \
 351     } STMT_END
 352
 353 /* loop context */
 354 struct block_loop {
 355     char *      label;
 356     I32         resetsp;
 357     OP *        redo_op;
 358     OP *        next_op;
 359     OP *        last_op;
 360 #ifdef USE_ITHREADS
 361     void *      iterdata;
 362     PAD         *oldcomppad;
 363 #else
 364     SV **       itervar;
 365 #endif
 366     SV *        itersave;
 367     SV *        iterlval;
 368     AV *        iterary;
 369     IV          iterix;
 370     IV          itermax;
 371 };
 372
 373 #ifdef USE_ITHREADS
 374 #  define CxITERVAR(c)                                                  \
 375         ((c)->blk_loop.iterdata                                         \
 376          ? (CxPADLOOP(cx)                                               \
 377             ? &CX_CURPAD_SV( (c)->blk_loop,                             \
 378                     INT2PTR(PADOFFSET, (c)->blk_loop.iterdata))         \
 379             : &GvSV((GV*)(c)->blk_loop.iterdata))                       \
 380          : (SV**)NULL)
 381 #  define CX_ITERDATA_SET(cx,idata)                                     \
 382         CX_CURPAD_SAVE(cx->blk_loop);                                   \
 383         if ((cx->blk_loop.iterdata = (idata)))                          \
 384             cx->blk_loop.itersave = SvREFCNT_inc(*CxITERVAR(cx));       \
 385         else                                                            \
 386             cx->blk_loop.itersave = Nullsv;
 387 #else
 388 #  define CxITERVAR(c)          ((c)->blk_loop.itervar)
 389 #  define CX_ITERDATA_SET(cx,ivar)                                      \
 390         if ((cx->blk_loop.itervar = (SV**)(ivar)))                      \
 391             cx->blk_loop.itersave = SvREFCNT_inc(*CxITERVAR(cx));       \
 392         else                                                            \
 393             cx->blk_loop.itersave = Nullsv;
 394 #endif
 395
 396 #define PUSHLOOP(cx, dat, s)                                            \
 397         cx->blk_loop.label = PL_curcop->cop_label;                      \
 398         cx->blk_loop.resetsp = s - PL_stack_base;                       \
 399         cx->blk_loop.redo_op = cLOOP->op_redoop;                        \
 400         cx->blk_loop.next_op = cLOOP->op_nextop;                        \
 401         cx->blk_loop.last_op = cLOOP->op_lastop;                        \
 402         cx->blk_loop.iterlval = Nullsv;                                 \
 403         cx->blk_loop.iterary = Nullav;                                  \
 404         cx->blk_loop.iterix = -1;                                       \
 405         CX_ITERDATA_SET(cx,dat);
 406
 407 #define POPLOOP(cx)                                                     \
 408         SvREFCNT_dec(cx->blk_loop.iterlval);                            \
 409         if (CxITERVAR(cx)) {                                            \
 410             SV **s_v_p = CxITERVAR(cx);                                 \
 411             sv_2mortal(*s_v_p);                                         \
 412             *s_v_p = cx->blk_loop.itersave;                             \
 413         }                                                               \
 414         if (cx->blk_loop.iterary && cx->blk_loop.iterary != PL_curstack)\
 415             SvREFCNT_dec(cx->blk_loop.iterary);
 416
 417 /* context common to subroutines, evals and loops */
 418 struct block {
 419     I32         blku_oldsp;     /* stack pointer to copy stuff down to */
 420     COP *       blku_oldcop;    /* old curcop pointer */
 421     I32         blku_oldmarksp; /* mark stack index */
 422     I32         blku_oldscopesp;        /* scope stack index */
 423     PMOP *      blku_oldpm;     /* values of pattern match vars */
 424     U8          blku_gimme;     /* is this block running in list context? */
 425
 426     union {
 427         struct block_sub        blku_sub;
 428         struct block_eval       blku_eval;
 429         struct block_loop       blku_loop;
 430     } blk_u;
 431 };
 432 #define blk_oldsp       cx_u.cx_blk.blku_oldsp
 433 #define blk_oldcop      cx_u.cx_blk.blku_oldcop
 434 #define blk_oldmarksp   cx_u.cx_blk.blku_oldmarksp
 435 #define blk_oldscopesp  cx_u.cx_blk.blku_oldscopesp
 436 #define blk_oldpm       cx_u.cx_blk.blku_oldpm
 437 #define blk_gimme       cx_u.cx_blk.blku_gimme
 438 #define blk_sub         cx_u.cx_blk.blk_u.blku_sub
 439 #define blk_eval        cx_u.cx_blk.blk_u.blku_eval
 440 #define blk_loop        cx_u.cx_blk.blk_u.blku_loop
 441
 442 /* Enter a block. */
 443 #define PUSHBLOCK(cx,t,sp) CXINC, cx = &cxstack[cxstack_ix],            \
 444         cx->cx_type             = t,                                    \
 445         cx->blk_oldsp           = sp - PL_stack_base,                   \
 446         cx->blk_oldcop          = PL_curcop,                            \
 447         cx->blk_oldmarksp       = PL_markstack_ptr - PL_markstack,      \
 448         cx->blk_oldscopesp      = PL_scopestack_ix,                     \
 449         cx->blk_oldpm           = PL_curpm,                             \
 450         cx->blk_gimme           = (U8)gimme;                            \
 451         DEBUG_l( PerlIO_printf(Perl_debug_log, "Entering block %ld, type %s\n", \
 452                     (long)cxstack_ix, PL_block_type[CxTYPE(cx)]); )
 453
 454 /* Exit a block (RETURN and LAST). */
 455 #define POPBLOCK(cx,pm) cx = &cxstack[cxstack_ix--],                    \
 456         newsp            = PL_stack_base + cx->blk_oldsp,               \
 457         PL_curcop        = cx->blk_oldcop,                              \
 458         PL_markstack_ptr = PL_markstack + cx->blk_oldmarksp,            \
 459         PL_scopestack_ix = cx->blk_oldscopesp,                          \
 460         pm               = cx->blk_oldpm,                               \
 461         gimme            = cx->blk_gimme;                               \
 462         DEBUG_SCOPE("POPBLOCK");                                        \
 463         DEBUG_l( PerlIO_printf(Perl_debug_log, "Leaving block %ld, type %s\n",          \
 464                     (long)cxstack_ix+1,PL_block_type[CxTYPE(cx)]); )
 465
 466 /* Continue a block elsewhere (NEXT and REDO). */
 467 #define TOPBLOCK(cx) cx  = &cxstack[cxstack_ix],                        \
 468         PL_stack_sp      = PL_stack_base + cx->blk_oldsp,               \
 469         PL_markstack_ptr = PL_markstack + cx->blk_oldmarksp,            \
 470         PL_scopestack_ix = cx->blk_oldscopesp,                          \
 471         PL_curpm         = cx->blk_oldpm;                               \
 472         DEBUG_SCOPE("TOPBLOCK");
 473
 474 /* substitution context */
 475 struct subst {
 476     I32         sbu_iters;
 477     I32         sbu_maxiters;
 478     I32         sbu_rflags;
 479     I32         sbu_oldsave;
 480     bool        sbu_once;
 481     bool        sbu_rxtainted;
 482     char *      sbu_orig;
 483     SV *        sbu_dstr;
 484     SV *        sbu_targ;
 485     char *      sbu_s;
 486     char *      sbu_m;
 487     char *      sbu_strend;
 488     void *      sbu_rxres;
 489     REGEXP *    sbu_rx;
 490 };
 491 #define sb_iters        cx_u.cx_subst.sbu_iters
 492 #define sb_maxiters     cx_u.cx_subst.sbu_maxiters
 493 #define sb_rflags       cx_u.cx_subst.sbu_rflags
 494 #define sb_oldsave      cx_u.cx_subst.sbu_oldsave
 495 #define sb_once         cx_u.cx_subst.sbu_once
 496 #define sb_rxtainted    cx_u.cx_subst.sbu_rxtainted
 497 #define sb_orig         cx_u.cx_subst.sbu_orig
 498 #define sb_dstr         cx_u.cx_subst.sbu_dstr
 499 #define sb_targ         cx_u.cx_subst.sbu_targ
 500 #define sb_s            cx_u.cx_subst.sbu_s
 501 #define sb_m            cx_u.cx_subst.sbu_m
 502 #define sb_strend       cx_u.cx_subst.sbu_strend
 503 #define sb_rxres        cx_u.cx_subst.sbu_rxres
 504 #define sb_rx           cx_u.cx_subst.sbu_rx
 505
 506 #define PUSHSUBST(cx) CXINC, cx = &cxstack[cxstack_ix],                 \
 507         cx->sb_iters            = iters,                                \
 508         cx->sb_maxiters         = maxiters,                             \
 509         cx->sb_rflags           = r_flags,                              \
 510         cx->sb_oldsave          = oldsave,                              \
 511         cx->sb_once             = once,                                 \
 512         cx->sb_rxtainted        = rxtainted,                            \
 513         cx->sb_orig             = orig,                                 \
 514         cx->sb_dstr             = dstr,                                 \
 515         cx->sb_targ             = targ,                                 \
 516         cx->sb_s                = s,                                    \
 517         cx->sb_m                = m,                                    \
 518         cx->sb_strend           = strend,                               \
 519         cx->sb_rxres            = Null(void*),                          \
 520         cx->sb_rx               = rx,                                   \
 521         cx->cx_type             = CXt_SUBST;                            \
 522         rxres_save(&cx->sb_rxres, rx)
 523
 524 #define POPSUBST(cx) cx = &cxstack[cxstack_ix--];                       \
 525         rxres_free(&cx->sb_rxres)
 526
 527 struct context {
 528     U32         cx_type;        /* what kind of context this is */
 529     union {
 530         struct block    cx_blk;
 531         struct subst    cx_subst;
 532     } cx_u;
 533 };
 534
 535 #define CXTYPEMASK      0xff
 536 #define CXt_NULL        0
 537 #define CXt_SUB         1
 538 #define CXt_EVAL        2
 539 #define CXt_LOOP        3
 540 #define CXt_SUBST       4
 541 #define CXt_BLOCK       5
 542 #define CXt_FORMAT      6
 543
 544 /* private flags for CXt_EVAL */
 545 #define CXp_REAL        0x00000100      /* truly eval'', not a lookalike */
 546 #define CXp_TRYBLOCK    0x00000200      /* eval{}, not eval'' or similar */
 547
 548 #ifdef USE_ITHREADS
 549 /* private flags for CXt_LOOP */
 550 #  define CXp_PADVAR    0x00000100      /* itervar lives on pad, iterdata
 551                                            has pad offset; if not set,
 552                                            iterdata holds GV* */
 553 #  define CxPADLOOP(c)  (((c)->cx_type & (CXt_LOOP|CXp_PADVAR))         \
 554                          == (CXt_LOOP|CXp_PADVAR))
 555 #endif
 556
 557 #define CxTYPE(c)       ((c)->cx_type & CXTYPEMASK)
 558 #define CxREALEVAL(c)   (((c)->cx_type & (CXt_EVAL|CXp_REAL))           \
 559                          == (CXt_EVAL|CXp_REAL))
 560 #define CxTRYBLOCK(c)   (((c)->cx_type & (CXt_EVAL|CXp_TRYBLOCK))       \
 561                          == (CXt_EVAL|CXp_TRYBLOCK))
 562
 563 #define CXINC (cxstack_ix < cxstack_max ? ++cxstack_ix : (cxstack_ix = cxinc()))
 564
 565 /*
 566 =head1 "Gimme" Values
 567 */
 568
 569 /*
 570 =for apidoc AmU||G_SCALAR
 571 Used to indicate scalar context.  See C<GIMME_V>, C<GIMME>, and
 572 L<perlcall>.
 573
 574 =for apidoc AmU||G_ARRAY
 575 Used to indicate list context.  See C<GIMME_V>, C<GIMME> and
 576 L<perlcall>.
 577
 578 =for apidoc AmU||G_VOID
 579 Used to indicate void context.  See C<GIMME_V> and L<perlcall>.
 580
 581 =for apidoc AmU||G_DISCARD
 582 Indicates that arguments returned from a callback should be discarded.  See
 583 L<perlcall>.
 584
 585 =for apidoc AmU||G_EVAL
 586
 587 Used to force a Perl C<eval> wrapper around a callback.  See
 588 L<perlcall>.
 589
 590 =for apidoc AmU||G_NOARGS
 591
 592 Indicates that no arguments are being sent to a callback.  See
 593 L<perlcall>.
 594
 595 =cut
 596 */
 597
 598 #define G_SCALAR        0
 599 #define G_ARRAY         1
 600 #define G_VOID          128     /* skip this bit when adding flags below */
 601
 602 /* extra flags for Perl_call_* routines */
 603 #define G_DISCARD       2       /* Call FREETMPS. */
 604 #define G_EVAL          4       /* Assume eval {} around subroutine call. */
 605 #define G_NOARGS        8       /* Don't construct a @_ array. */
 606 #define G_KEEPERR      16       /* Append errors to $@, don't overwrite it */
 607 #define G_NODEBUG      32       /* Disable debugging at toplevel.  */
 608 #define G_METHOD       64       /* Calling method. */
 609
 610 /* flag bits for PL_in_eval */
 611 #define EVAL_NULL       0       /* not in an eval */
 612 #define EVAL_INEVAL     1       /* some enclosing scope is an eval */
 613 #define EVAL_WARNONLY   2       /* used by yywarn() when calling yyerror() */
 614 #define EVAL_KEEPERR    4       /* set by Perl_call_sv if G_KEEPERR */
 615 #define EVAL_INREQUIRE  8       /* The code is being required. */
 616
 617 /* Support for switching (stack and block) contexts.
 618  * This ensures magic doesn't invalidate local stack and cx pointers.
 619  */
 620
 621 #define PERLSI_UNKNOWN          -1
 622 #define PERLSI_UNDEF            0
 623 #define PERLSI_MAIN             1
 624 #define PERLSI_MAGIC            2
 625 #define PERLSI_SORT             3
 626 #define PERLSI_SIGNAL           4
 627 #define PERLSI_OVERLOAD         5
 628 #define PERLSI_DESTROY          6
 629 #define PERLSI_WARNHOOK         7
 630 #define PERLSI_DIEHOOK          8
 631 #define PERLSI_REQUIRE          9
 632
 633 struct stackinfo {
 634     AV *                si_stack;       /* stack for current runlevel */
 635     PERL_CONTEXT *      si_cxstack;     /* context stack for runlevel */
 636     I32                 si_cxix;        /* current context index */
 637     I32                 si_cxmax;       /* maximum allocated index */
 638     I32                 si_type;        /* type of runlevel */
 639     struct stackinfo *  si_prev;
 640     struct stackinfo *  si_next;
 641     I32                 si_markoff;     /* offset where markstack begins for us.
 642                                          * currently used only with DEBUGGING,
 643                                          * but not #ifdef-ed for bincompat */
 644 };
 645
 646 typedef struct stackinfo PERL_SI;
 647
 648 #define cxstack         (PL_curstackinfo->si_cxstack)
 649 #define cxstack_ix      (PL_curstackinfo->si_cxix)
 650 #define cxstack_max     (PL_curstackinfo->si_cxmax)
 651
 652 #ifdef DEBUGGING
 653 #  define       SET_MARK_OFFSET \
 654     PL_curstackinfo->si_markoff = PL_markstack_ptr - PL_markstack
 655 #else
 656 #  define       SET_MARK_OFFSET NOOP
 657 #endif
 658
 659 #define PUSHSTACKi(type) \
 660     STMT_START {                                                        \
 661         PERL_SI *next = PL_curstackinfo->si_next;                       \
 662         if (!next) {                                                    \
 663             next = new_stackinfo(32, 2048/sizeof(PERL_CONTEXT) - 1);    \
 664             next->si_prev = PL_curstackinfo;                            \
 665             PL_curstackinfo->si_next = next;                            \
 666         }                                                               \
 667         next->si_type = type;                                           \
 668         next->si_cxix = -1;                                             \
 669         AvFILLp(next->si_stack) = 0;                                    \
 670         SWITCHSTACK(PL_curstack,next->si_stack);                        \
 671         PL_curstackinfo = next;                                         \
 672         SET_MARK_OFFSET;                                                \
 673     } STMT_END
 674
 675 #define PUSHSTACK PUSHSTACKi(PERLSI_UNKNOWN)
 676
 677 /* POPSTACK works with PL_stack_sp, so it may need to be bracketed by
 678  * PUTBACK/SPAGAIN to flush/refresh any local SP that may be active */
 679 #define POPSTACK \
 680     STMT_START {                                                        \
 681         dSP;                                                            \
 682         PERL_SI *prev = PL_curstackinfo->si_prev;                       \
 683         if (!prev) {                                                    \
 684             PerlIO_printf(Perl_error_log, "panic: POPSTACK\n");         \
 685             my_exit(1);                                                 \
 686         }                                                               \
 687         SWITCHSTACK(PL_curstack,prev->si_stack);                        \
 688         /* don't free prev here, free them all at the END{} */          \
 689         PL_curstackinfo = prev;                                         \
 690     } STMT_END
 691
 692 #define POPSTACK_TO(s) \
 693     STMT_START {                                                        \
 694         while (PL_curstack != s) {                                      \
 695             dounwind(-1);                                               \
 696             POPSTACK;                                                   \
 697         }                                                               \
 698     } STMT_END
 699
 700 #define IN_PERL_COMPILETIME     (PL_curcop == &PL_compiling)
 701 #define IN_PERL_RUNTIME         (PL_curcop != &PL_compiling)
 702