cperl-toggle-set-debug-unwind is an interactive compiled Lisp function in `cperl-mode.el'.

(cperl-toggle-set-debug-unwind ARG &optional BACKTRACE)

Toggle (or, with numeric argument, set) debugging state of syntaxification.
Nonpositive numeric argument disables debugging messages. The message
summarizes which regions it was decided to rescan for syntactic constructs.

The message looks like this:

Syxify req=123..138 actual=101..146 done-to: 112=>146 statepos: 73=>117

Numbers are character positions in the buffer. REQ provides the range to
rescan requested by `font-lock'. ACTUAL is the range actually resyntaxified;
for correct operation it should start and end outside any special syntactic
construct. DONE-TO and STATEPOS indicate changes to internal caches maintained
by CPerl.