NAME

       B::Op_private -  OP op_private flag definitions

SYNOPSIS

           use B::Op_private;

           # flag details for bit 7 of OP_AELEM's op_private:
           my $name  = $B::Op_private::bits{aelem}{7}; # OPpLVAL_INTRO
           my $value = $B::Op_private::defines{$name}; # 128
           my $label = $B::Op_private::labels{$name};  # LVINTRO

           # the bit field at bits 5..6 of OP_AELEM's op_private:
           my $bf  = $B::Op_private::bits{aelem}{6};
           my $mask = $bf->{bitmask}; # etc

DESCRIPTION

       This module provides four global hashes:

           %B::Op_private::bits
           %B::Op_private::defines
           %B::Op_private::labels
           %B::Op_private::ops_using

       which contain information about the per-op meanings of the bits in the op_private field.

   %bits
       This is indexed by op name and then bit number (0..7). For single bit flags, it returns
       the name of the define (if any) for that bit:

          $B::Op_private::bits{aelem}{7} eq 'OPpLVAL_INTRO';

       For bit fields, it returns a hash ref containing details about the field.  The same
       reference will be returned for all bit positions that make up the bit field; so for
       example these both return the same hash ref:

           $bitfield = $B::Op_private::bits{aelem}{5};
           $bitfield = $B::Op_private::bits{aelem}{6};

       The general format of this hash ref is

           {
               # The bit range and mask; these are always present.
               bitmin        => 5,
               bitmax        => 6,
               bitmask       => 0x60,

               # (The remaining keys are optional)

               # The names of any defines that were requested:
               mask_def      => 'OPpFOO_MASK',
               baseshift_def => 'OPpFOO_SHIFT',
               bitcount_def  => 'OPpFOO_BITS',

               # If present, Concise etc will display the value with a 'FOO='
               # prefix. If it equals '-', then Concise will treat the bit
               # field as raw bits and not try to interpret it.
               label         => 'FOO',

               # If present, specifies the names of some defines and the
               # display labels that are used to assign meaning to particu-
               # lar integer values within the bit field; e.g. 3 is dis-
               # played as 'C'.
               enum          => [ qw(
                                    1   OPpFOO_A  A
                                    2   OPpFOO_B  B
                                    3   OPpFOO_C  C
                                )],

           };

   %defines
       This gives the value of every "OPp" define, e.g.

           $B::Op_private::defines{OPpLVAL_INTRO} == 128;

   %labels
       This gives the short display label for each define, as used by "B::Concise" and "perl
       -Dx", e.g.

           $B::Op_private::labels{OPpLVAL_INTRO} eq 'LVINTRO';

       If the label equals '-', then Concise will treat the bit as a raw bit and not try to
       display it symbolically.

   %ops_using
       For each define, this gives a reference to an array of op names that use the flag.

           @ops_using_lvintro = @{ $B::Op_private::ops_using{OPp_LVAL_INTRO} };