proposition: Lemma space_start_is_pointer_or_null: forall (g: LGraph) (h: heap) i, graph_heap_compatible g h -> 0 <= i < Zlength (spaces h) -> is_pointer_or_null (space_start (Znth i (spaces h))).
proof: Proof. intros. destruct (graph_has_gen_dec g (Z.to_nat i)). - apply val_lemmas.isptr_is_pointer_or_null. eapply space_start_isptr; eauto. - cut (space_start (Znth i (spaces h)) = nullval). + intros. rewrite H1. apply mapsto_memory_block.is_pointer_or_null_nullval. + eapply space_start_isnull; eauto. Qed.
imports: Coq.ZArith.ZArith Coq.Program.Basics Coq.micromega.Lia compcert.lib.Integers compcert.common.Values VST.veric.base VST.veric.Clight_lemmas VST.veric.val_lemmas VST.veric.shares VST.msl.seplog VST.msl.shares VST.zlist.sublist VST.floyd.coqlib3 VST.floyd.functional_base VST.floyd.data_at_rec_lemmas VST.zlist.list_solver CertiGraph.lib.EquivDec_ext CertiGraph.lib.List_ext CertiGraph.graph.graph_model CertiGraph.graph.graph_gen