Module ExtrFacts := GenExtrFacts (Def) (Conseq) (Extr).

Theorem semax_ptr_compare_backward: forall {CS: compspecs} {Espec: OracleKind} (Delta: tycontext),
forall P id e,
@semax CS Espec Delta
(EX cmp: Cop.binary_operation, EX e1: expr, EX e2: expr,
EX ty: type, EX sh1: share, EX sh2: share,
!! (e = Ebinop cmp e1 e2 ty /\
sepalg.nonidentity sh1 /\ sepalg.nonidentity sh2 /\
is_comparison cmp = true /\
eqb_type (typeof e1) int_or_ptr_type = false /\
eqb_type (typeof e2) int_or_ptr_type = false /\
typecheck_tid_ptr_compare Delta id = true) &&
( |> ( (tc_expr Delta e1) &&
(tc_expr Delta e2)  &&
local (`(blocks_match cmp) (eval_expr e1) (eval_expr e2)) &&
(`(mapsto_ sh1 (typeof e1)) (eval_expr e1) * TT) &&
(`(mapsto_ sh2 (typeof e2)) (eval_expr e2) * TT) &&
subst id (eval_expr (Ebinop cmp e1 e2 ty)) P)))
(Sset id e)
(normal_ret_assert P).