Definition isGlobalBlock {F V : Type} (ge : Genv.t F V) :=
  fun b => (fst (genv2blocksBool ge)) b || (snd (genv2blocksBool ge)) b.

Lemma meminj_preserves_globals_isGlobalBlock: forall {F V} (g: Genv.t F V) j (PG: meminj_preserves_globals g j) b (GB: isGlobalBlock g b = true), j b = Some (b, 0).