This function causes an immediate core dump. See also the -u command-line switch in perlrun, which does the same thing. Primarily this is so that you can use the undump program (not supplied) to turn your core dump into an executable binary after having initialized all your variables at the beginning of the program. When the new binary is executed it will begin by executing a goto LABEL (with all the restrictions that goto suffers). Think of it as a goto with an intervening core dump and reincarnation. If LABEL is omitted, restarts the program from the top. The dump EXPR form, available starting in Perl 5.18.0, allows a name to be computed at run time, being otherwise identical to dump LABEL.
WARNING: Any files opened at the time of the dump will not be open any more when the program is reincarnated, with possible resulting confusion by Perl.
This function is now largely obsolete, mostly because it's very hard to convert a core file into an executable. As of Perl 5.30, it must be invoked as CORE::dump().
Unlike most named operators, this has the same precedence as assignment. It is also exempt from the looks-like-a-function rule, so dump ("foo")."bar" will cause "bar" to be part of the argument to dump.
Portability issues: "dump" in perlport.