http://www.perlmonks.org?node_id=760415


in reply to Re^3: elsif chain vs. dispatch
in thread elsif chain vs. dispatch

A measure was added to 5.8.1 to thwart the intentional exercise of the degenerate case.

I don't see anything in there or in the linked section of perlsec about detecting the accidental exercise of the degenerate case, but it's possible. (It's even likely.)

if (n_links > HV_MAX_LENGTH_BEFORE_SPLIT) in hv.c in perl.git might be that very check.