$ perl -MO=Terse,-exec -e '$v1.$v2.$v3'
OP (0x16e5ad0) enter 
COP (0x1817650) nextstate 
PADOP (0x16e6eb0) gvsv  GV (0x16e3b68) *v1 
PADOP (0x16e5b80) gvsv  GV (0x16e3b98) *v2 
BINOP (0x16e5a50) concat [3] 
PADOP (0x16e4c00) gvsv  GV (0x16bee88) *v3 
BINOP (0x16d5aa0) concat [5] 
LISTOP (0x16e4ca0) leave [1] 
-e syntax OK
$ perl -MO=Terse,-exec -e '"$v1$v2$v3"'
OP (0x1ecc200) enter 
COP (0x200d6b0) nextstate 
PADOP (0x1edac60) gvsv  GV (0x1ed9b80) *v1 
PADOP (0x1edbd40) gvsv  GV (0x1ed9ca0) *v2 
BINOP (0x1edba90) concat [3] 
PADOP (0x1edba50) gvsv  GV (0x1eb4e88) *v3 
BINOP (0x1ecbaa0) concat [5] 
LISTOP (0x1edb9d0) leave [1] 
-e syntax OK