Basic block may end enlarging the number of instructions?

[DanieleParravicini]

Is it possible that basic blocks ends executing the very same instructions?

[DanieleParravicini]

yes it is possible.

Consider the following example

Imagine that BB0 executes 0 and produces 1/2.
To gain advantage from other basic blocks it moves 2 to BB1.
BB0 then executes 1 and store 2 in fifo related to next char
BB1 execute 2 and produces 3/4. 3 is moved to BB0 and 4 is kept in BB1.
In the end
BB0 next: 2,4
BB1 next: 5.
Once new char is fetched 4 will be executed 2 times.

1. because BB0 has 4 in its fifo.
2. because of istruction 2->3,4
   4 can be avoided in principle