Definition alloc_left_sm (mu: SM_Injection) b1 b2 delta: SM_Injection :=
  Build_SM_Injection (fun b => eq_block b b1 || locBlocksSrc mu b)
                     (locBlocksTgt mu) (*b2 is already in locBlocksTgt!*)
                     (pubBlocksSrc mu) (pubBlocksTgt mu)
                     (fun b => if eq_block b b1 then Some(b2, delta)
                               else local_of mu b)
                     (extBlocksSrc mu) (extBlocksTgt mu)
                     (frgnBlocksSrc mu) (frgnBlocksTgt mu) (extern_of mu).

Lemma genv_find_add_globals_fresh: forall {F V} defs (g:Genv.t F V) i (G: ~ In i (map fst defs)), Genv.find_symbol (Genv.add_globals g defs) i = Genv.find_symbol g i.