$ gdb perl5.8.7
GNU gdb 6.3.50_2004-12-28-cvs (cygwin-special)
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This GDB was configured as "i686-pc-cygwin"...
(gdb) set args -we'![a=>{b=>0,c=>1},sub{"foo"}]'
(gdb) b Perl_pp_not
Function "Perl_pp_not" not defined.
Make breakpoint pending on future shared library load? (y or [n]) y

Breakpoint 1 (Perl_pp_not) pending.
(gdb) r
Starting program: /usr/local/bin/perl5.8.7.exe -we'![a=>{b=>0,c=>1},sub{"foo"}]'


Breakpoint 2 at 0x100bbe8f: file pp.c, line 2396.
Pending breakpoint "Perl_pp_not" resolved
Useless use of not in void context at -e line 1.

Breakpoint 2, Perl_pp_not (my_perl=0x103c1f58) at pp.c:2396
2396        dSP; tryAMAGICunSET(not);
(gdb) s
2397        *PL_stack_sp = boolSV(!SvTRUE(*PL_stack_sp));
(gdb) call Perl_do_sv_dump(Perl_get_context(),0,Perl_PerlIO_stderr(Perl_get_con
text()),*sp,0,4,0,0)
SV = RV(0x103e9824) at 0x103e7588
  REFCNT = 1
  FLAGS = (TEMP,ROK)
  RV = 0x103c323c
    SV = PVAV(0x103e9c40) at 0x103c323c
      REFCNT = 2
      FLAGS = ()
      IV = 0
      NV = 0
      ARRAY = 0x103c9ba8
      FILL = 2
      MAX = 2
      ARYLEN = 0x0
      FLAGS = (REAL)
        Elt No. 0
        SV = PV(0x103c3468) at 0x103e7564
          REFCNT = 1
          FLAGS = (POK,pPOK)
          PV = 0x103c4898 "a"\0
          CUR = 1
          LEN = 2
        Elt No. 1
        SV = RV(0x103e981c) at 0x103e7570
          REFCNT = 1
          FLAGS = (ROK)
          RV = 0x103c3188
            SV = PVHV(0x103e2990) at 0x103c3188
              REFCNT = 3
              FLAGS = (SHAREKEYS)
              IV = 2
              NV = 0
              ARRAY = 0x103e8e48  (0:6, 1:2)
              hash quality = 125.0%
              KEYS = 2
              FILL = 2
              MAX = 7
              RITER = -1
              EITER = 0x0
                Elt "c" HASH = 0xeeba5d59
                SV = IV(0x103e9428) at 0x103e74a4
                  REFCNT = 1
                  FLAGS = (IOK,pIOK)
                  IV = 1
        Elt No. 2
        SV = RV(0x103e9820) at 0x103e757c
          REFCNT = 1
          FLAGS = (ROK)
          RV = 0x103e7504
            SV = PVCV(0x103e0f08) at 0x103e7504
              REFCNT = 3
              FLAGS = (PADBUSY,PADMY,ANON,WEAKOUTSIDE)
              IV = 0
              NV = 0
              COMP_STASH = 0x103c30b0   "main"
              START = 0x103e5608 ===> 1
              ROOT = 0x103eaa48
              XSUB = 0x0
              XSUBANY = 0
              GVGV::GV = 0x103e7534     "main" :: "__ANON__"
              FILE = "-e"
              DEPTH = 0
              FLAGS = 0x404
              OUTSIDE_SEQ = 0
              PADLIST = 0x103e7510
                PADNAME = 0x103e751c(0x103e7ce8) PAD = 0x103e7528(0x103e7c68)
              OUTSIDE = 0x103c32b4 (MAIN)
(gdb)

##</code><code>##

Perl_do_sv_dump(pTHX_ I32 level, PerlIO *file, SV *sv, I32 nest, I32 maxnest, bool dumpops, STRLEN pvlim)