perl -c -Mre=debug -e 'm/123*/'
Freeing REx: `","'
Compiling REx `123*'
size 6 Got 52 bytes for offset annotations.
first at 1
rarest char 2 at 1
   1: EXACT <12>(3)
   3: STAR(6)
   4:   EXACT <3>(0)
   6: END(0)
...