(** ** Properties of contexts and relocations *)
Remark sreg_below_diff:
forall ctx r r', Plt r' ctx.(dreg) -> sreg ctx r <> r'.
Remark context_below_diff:
forall ctx1 ctx2 r1 r2,
context_below ctx1 ctx2 -> Ple r1 ctx1.(mreg) -> sreg ctx1 r1 <> sreg ctx2 r2.
Remark context_below_lt:
forall ctx1 ctx2 r, context_below ctx1 ctx2 -> Ple r ctx1.(mreg) -> Plt (sreg ctx1 r) ctx2.(dreg).
(* Remark context_below_le: forall ctx1 ctx2 r, context_below ctx1 ctx2 -> Ple r ctx1.(mreg) -> Ple (sreg ctx1 r) ctx2.(dreg). *)
(** ** Agreement between register sets before and after inlining. *)
Definition agree_regs (F: meminj) (ctx: context) (rs rs': regset) :=
(forall r, Ple r ctx.(mreg) -> Val.inject F rs#r rs'#(sreg ctx r))
/\(forall r, Plt ctx.(mreg) r -> rs#r = Vundef).
Definition val_reg_charact (F: meminj) (ctx: context) (rs': regset) (v: val) (r: reg) :=
(Plt ctx.(mreg) r /\ v = Vundef) \/ (Ple r ctx.(mreg) /\ Val.inject F v rs'#(sreg ctx r)).
Remark Plt_Ple_dec:
forall p q, {Plt p q} + {Ple q p}.

Lemma agree_regs_invariant:
forall F ctx rs rs1 rs2,
agree_regs F ctx rs rs1 ->
(forall r, Ple ctx.(dreg) r -> Plt r (ctx.(dreg) + ctx.(mreg)) -> rs2#r = rs1#r) ->
agree_regs F ctx rs rs2.