use strict;
use warnings;
use feature qw( say );

use B qw( svref_2object );

my $x = ( 1 << 54 ) | 1;
say $x;  # 18014398509481985

# Add the value as an NV to the scalar.
{ no warnings qw( void ); log $x; }

# Make it so the scalar contains just an NV.
$x = svref_2object(\$x)->NV;

# Add the value as an IV or UV to the scalar.
{ no warnings qw( void ); $x | 1; }

# Make it so the scalar contains just an IV or UV.
$x = svref_2object(\$x)->int_value;

say $x;  # 18014398509481984