$ perl -MO=Terse -e '$v1.$v2.$v3'
LISTOP (0x9dc5fe0) leave [1] 
    OP (0x9dc6768) enter 
    COP (0x9dd0650) nextstate 
    BINOP (0x9dd06e0) concat [2] 
        BINOP (0x9dd05b0) concat [1] 
            UNOP (0x9dd0688) null [15] 
                SVOP (0x9dd07e8) gvsv  GV (0x9dcaa30) *v1 
            UNOP (0x9dd0578) null [15] 
                SVOP (0x9dd0630) gvsv  GV (0x9dcaa58) *v2 
        UNOP (0x9dd05d0) null [15] 
            SVOP (0x9dcf9e0) gvsv  GV (0x9dcaae4) *v3 
-e syntax OK
$ perl -MO=Terse -e '"$v1$v2$v3"'
LISTOP (0x8b92778) leave [1] 
    OP (0x8b88768) enter 
    COP (0x8b92650) nextstate 
    UNOP (0x8b926e0) null [67] 
        OP (0x8b918d0) null [3] 
        BINOP (0x8b925d0) concat [2] 
            BINOP (0x8b925b0) concat [1] 
                UNOP (0x8b92688) null [15] 
                    SVOP (0x8b927e8) gvsv  GV (0x8b8ca44) *v1 
                UNOP (0x8b92578) null [15] 
                    SVOP (0x8b92630) gvsv  GV (0x8b8cb34) *v2 
            UNOP (0x8b91920) null [15] 
                SVOP (0x8b91a10) gvsv  GV (0x8b8cae4) *v3 
-e syntax OK