NAME
    B::Debugger - optree debugger

SYNOPSIS
      perl -MB::Debugger programm.pl
      B::Debugger 0.01 - optree debugger. h for help
      op 0 enter
      > n
      op 1 nextstate
      > h
      Usage:
      n [n] next op                       l [n|x-y]     list ops
      c [n] continue (until)              d|Debug       op
      b <n> break at op                   o|Concise     op
      s     step into kids                f|Flags       op
      sib   step to next sibling          x|eval expr
      u [n] up                            [sahpicg]v<n> n-th global var: sv1,
      g <n> goto                          pad <n>       n-th pad variable (my)
      h     help
      q     quit debugger, execute        exit           quit with no execution
      op 0 enter
      > b 5
      breakpoint 5 added
      > b const
      breakpoint const added
      > n
      op 2 pushmark
      > l
      -  <0> enter ->-
      -  <;> nextstate(main 111 test.pl:5) v:{ ->-
      -  <0> pushmark sM ->-  > c
      > q
      quit
      executing...

DESCRIPTION
      Start an optree inspector before the runtime execution begins, similar
      to the perl debugger, but only at the internal optree level, not the
      source level. Kind of interactive B::Concise.

      The ops are numbered and in basic (=parsed) order, starting from 0.
      Breakpoints can be defined as number or by opname.

OPTIONS
    None yet.

    Planned:

      -exec      switch to exec order
      -root      start at main_root, not main_start
      -check     hook into CHECK block (Default, at B)
      -unit      hook into UNITCHECK block (after B)
      -init      hook into INIT block (before B)
      -begin     hook into BEGIN block (before compilation)
      -d         debug, be verbose in the internal recursion steps

COMMANDS
      n [n]   goto the next op, or step the next n ops
      s       step into kid if not next
      sib     step to next sibling
      u [n]   go one or n steps back or up
      g <n>   goto op 0-opmax
      c [n]   continue. Optionally until op n
      l [n|x-y] list n ops or from x to y.
      x <x>   eval perl expression
      f       list B::Flags op
      o/C     list B::Concise op
      d/D     list B::Debug op
      [sahpicg]v<n> inspect n-th global variable. eg. sv1
      h       help
      q       quit debugger, start execution
      exit    quit perl, no execution

TODO
    See Od, freeze and thaw the optree and debug within perl5db in "INIT".

    Delay the "CHECK" block for B or run perl5db at the "CHECK" block.

    How to manage direct opidx access?

      Such as: Concise 10, list 5-10, up, sib
      Do a first sweep in desired basic or exec order recording the ops?

    set curcv in Concise

    Commandline options

    exit

    de-recursify and simplify the loop, cont is broken.

BUGS
    Plenty. This is alpha and for interested compiler developers only.

    l => coderef CODE(0x1553f40) has no START (set curcv in Concise)

    cont, goto broken

AUTHOR
    Reini Urban "rurban@cpan.org"