path: root/cfrontend/Cop.v

(* *********************************************************************)
(*                                                                     *)
(*              The Compcert verified compiler                         *)
(*                                                                     *)
(*          Xavier Leroy, INRIA Paris-Rocquencourt                     *)
(*                                                                     *)
(*  Copyright Institut National de Recherche en Informatique et en     *)
(*  Automatique.  All rights reserved.  This file is distributed       *)
(*  under the terms of the GNU General Public License as published by  *)
(*  the Free Software Foundation, either version 2 of the License, or  *)
(*  (at your option) any later version.  This file is also distributed *)
(*  under the terms of the INRIA Non-Commercial License Agreement.     *)
(*                                                                     *)
(* *********************************************************************)

(** Arithmetic and logical operators for the Compcert C and Clight languages *)

Require Import Coqlib.
Require Import AST.
Require Import Integers.
Require Import Floats.
Require Import Values.
Require Import Memory.
Require Import Ctypes.

(** * Syntax of operators. *)

Inductive unary_operation : Type :=
  | Onotbool : unary_operation          (**r boolean negation ([!] in C) *)
  | Onotint : unary_operation           (**r integer complement ([~] in C) *)
  | Oneg : unary_operation              (**r opposite (unary [-]) *)
  | Oabsfloat : unary_operation.        (**r floating-point absolute value *)

Inductive binary_operation : Type :=
  | Oadd : binary_operation             (**r addition (binary [+]) *)
  | Osub : binary_operation             (**r subtraction (binary [-]) *)
  | Omul : binary_operation             (**r multiplication (binary [*]) *)
  | Odiv : binary_operation             (**r division ([/]) *)
  | Omod : binary_operation             (**r remainder ([%]) *)
  | Oand : binary_operation             (**r bitwise and ([&]) *)
  | Oor : binary_operation              (**r bitwise or ([|]) *)
  | Oxor : binary_operation             (**r bitwise xor ([^]) *)
  | Oshl : binary_operation             (**r left shift ([<<]) *)
  | Oshr : binary_operation             (**r right shift ([>>]) *)
  | Oeq: binary_operation               (**r comparison ([==]) *)
  | One: binary_operation               (**r comparison ([!=]) *)
  | Olt: binary_operation               (**r comparison ([<]) *)
  | Ogt: binary_operation               (**r comparison ([>]) *)
  | Ole: binary_operation               (**r comparison ([<=]) *)
  | Oge: binary_operation.              (**r comparison ([>=]) *)

Inductive incr_or_decr : Type := Incr | Decr.

(** * Type classification and semantics of operators. *)

(** Most C operators are overloaded (they apply to arguments of various
  types) and their semantics depend on the types of their arguments.
  The following [classify_*] functions take as arguments the types
  of the arguments of an operation.  They return enough information
  to resolve overloading for this operator applications, such as
  ``both arguments are floats'', or ``the first is a pointer
  and the second is an integer''.  This classification is used in the
  compiler (module [Cshmgen]) to resolve overloading statically.

  The [sem_*] functions below compute the result of an operator
  application.  Since operators are overloaded, the result depends
  both on the static types of the arguments and on their run-time values.
  The corresponding [classify_*] function is first called on the 
  types of the arguments to resolve static overloading.  It is then
  followed by a case analysis on the values of the arguments. *)

(** ** Casts and truth values *)

Inductive classify_cast_cases : Type :=
  | cast_case_neutral                   (**r int|pointer -> int32|pointer *)
  | cast_case_i2i (sz2:intsize) (si2:signedness)   (**r int -> int *)
  | cast_case_f2f                                  (**r double -> double *)
  | cast_case_s2s                                  (**r single -> single *)
  | cast_case_f2s                                  (**r double -> single *)
  | cast_case_s2f                                  (**r single -> double *)
  | cast_case_i2f (si1: signedness)                (**r int -> double *)
  | cast_case_i2s (si1: signedness)                (**r int -> single *)
  | cast_case_f2i (sz2:intsize) (si2:signedness)   (**r double -> int *)
  | cast_case_s2i (sz2:intsize) (si2:signedness)   (**r single -> int *)
  | cast_case_l2l                       (**r long -> long *)
  | cast_case_i2l (si1: signedness)     (**r int -> long *)
  | cast_case_l2i (sz2: intsize) (si2: signedness) (**r long -> int *)
  | cast_case_l2f (si1: signedness)                (**r long -> double *)
  | cast_case_l2s (si1: signedness)                (**r long -> single *)
  | cast_case_f2l (si2:signedness)                 (**r double -> long *)
  | cast_case_s2l (si2:signedness)                 (**r single -> long *)
  | cast_case_f2bool                               (**r double -> bool *)
  | cast_case_s2bool                               (**r single -> bool *)
  | cast_case_l2bool                               (**r long -> bool *)
  | cast_case_p2bool                               (**r pointer -> bool *)
  | cast_case_struct (id1: ident) (fld1: fieldlist) (id2: ident) (fld2: fieldlist) (**r struct -> struct *)
  | cast_case_union (id1: ident) (fld1: fieldlist) (id2: ident) (fld2: fieldlist) (**r union -> union *)
  | cast_case_void                                 (**r any -> void *)
  | cast_case_default.

Definition classify_cast (tfrom tto: type) : classify_cast_cases :=
  match tto, tfrom with
  | Tint I32 si2 _, (Tint _ _ _ | Tpointer _ _ | Tcomp_ptr _ _ | Tarray _ _ _ | Tfunction _ _ _) => cast_case_neutral
  | Tint IBool _ _, Tfloat F64 _ => cast_case_f2bool
  | Tint IBool _ _, Tfloat F32 _ => cast_case_s2bool
  | Tint IBool _ _, (Tpointer _ _ | Tcomp_ptr _ _ | Tarray _ _ _ | Tfunction _ _ _) => cast_case_p2bool
  | Tint sz2 si2 _, Tint sz1 si1 _ => cast_case_i2i sz2 si2
  | Tint sz2 si2 _, Tfloat F64 _ => cast_case_f2i sz2 si2
  | Tint sz2 si2 _, Tfloat F32 _ => cast_case_s2i sz2 si2
  | Tfloat F64 _, Tfloat F64 _ => cast_case_f2f
  | Tfloat F32 _, Tfloat F32 _ => cast_case_s2s
  | Tfloat F64 _, Tfloat F32 _ => cast_case_s2f
  | Tfloat F32 _, Tfloat F64 _ => cast_case_f2s
  | Tfloat F64 _, Tint sz1 si1 _ => cast_case_i2f si1
  | Tfloat F32 _, Tint sz1 si1 _ => cast_case_i2s si1
  | (Tpointer _ _ | Tcomp_ptr _ _), (Tint _ _ _ | Tpointer _ _ | Tcomp_ptr _ _ | Tarray _ _ _ | Tfunction _ _ _) => cast_case_neutral
  | Tlong _ _, Tlong _ _ => cast_case_l2l
  | Tlong _ _, Tint sz1 si1 _ => cast_case_i2l si1
  | Tint IBool _ _, Tlong _ _ => cast_case_l2bool
  | Tint sz2 si2 _, Tlong _ _ => cast_case_l2i sz2 si2
  | Tlong si2 _, Tfloat F64 _ => cast_case_f2l si2
  | Tlong si2 _, Tfloat F32 _ => cast_case_s2l si2
  | Tfloat F64 _, Tlong si1 _ => cast_case_l2f si1
  | Tfloat F32 _, Tlong si1 _ => cast_case_l2s si1
  | (Tpointer _ _ | Tcomp_ptr _ _), Tlong _ _ => cast_case_l2i I32 Unsigned
  | Tlong si2 _, (Tpointer _ _ | Tcomp_ptr _ _ | Tarray _ _ _ | Tfunction _ _ _) => cast_case_i2l si2
  | Tstruct id2 fld2 _, Tstruct id1 fld1 _ => cast_case_struct id1 fld1 id2 fld2
  | Tunion id2 fld2 _, Tunion id1 fld1 _ => cast_case_union id1 fld1 id2 fld2
  | Tvoid, _ => cast_case_void
  | _, _ => cast_case_default
  end.

(** Semantics of casts.  [sem_cast v1 t1 t2 = Some v2] if value [v1],
  viewed with static type [t1], can be converted  to type [t2],
  resulting in value [v2].  *)

Definition cast_int_int (sz: intsize) (sg: signedness) (i: int) : int :=
  match sz, sg with
  | I8, Signed => Int.sign_ext 8 i
  | I8, Unsigned => Int.zero_ext 8 i
  | I16, Signed => Int.sign_ext 16 i
  | I16, Unsigned => Int.zero_ext 16 i 
  | I32, _ => i
  | IBool, _ => if Int.eq i Int.zero then Int.zero else Int.one
  end.

Definition cast_int_float (si: signedness) (i: int) : float :=
  match si with
  | Signed => Float.of_int i
  | Unsigned => Float.of_intu i
  end.

Definition cast_float_int (si : signedness) (f: float) : option int :=
  match si with
  | Signed => Float.to_int f
  | Unsigned => Float.to_intu f
  end.

Definition cast_int_single (si: signedness) (i: int) : float32 :=
  match si with
  | Signed => Float32.of_int i
  | Unsigned => Float32.of_intu i
  end.

Definition cast_single_int (si : signedness) (f: float32) : option int :=
  match si with
  | Signed => Float32.to_int f
  | Unsigned => Float32.to_intu f
  end.

Definition cast_int_long (si: signedness) (i: int) : int64 :=
  match si with
  | Signed => Int64.repr (Int.signed i)
  | Unsigned => Int64.repr (Int.unsigned i)
  end.

Definition cast_long_float (si: signedness) (i: int64) : float :=
  match si with
  | Signed => Float.of_long i
  | Unsigned => Float.of_longu i
  end.

Definition cast_long_single (si: signedness) (i: int64) : float32 :=
  match si with
  | Signed => Float32.of_long i
  | Unsigned => Float32.of_longu i
  end.

Definition cast_float_long (si : signedness) (f: float) : option int64 :=
  match si with
  | Signed => Float.to_long f
  | Unsigned => Float.to_longu f
  end.

Definition cast_single_long (si : signedness) (f: float32) : option int64 :=
  match si with
  | Signed => Float32.to_long f
  | Unsigned => Float32.to_longu f
  end.

Definition sem_cast (v: val) (t1 t2: type) : option val :=
  match classify_cast t1 t2 with
  | cast_case_neutral =>
      match v with
      | Vint _ | Vptr _ _ => Some v
      | _ => None
      end
  | cast_case_i2i sz2 si2 =>
      match v with
      | Vint i => Some (Vint (cast_int_int sz2 si2 i))
      | _ => None
      end
  | cast_case_f2f =>
      match v with
      | Vfloat f => Some (Vfloat f)
      | _ => None
      end
  | cast_case_s2s =>
      match v with
      | Vsingle f => Some (Vsingle f)
      | _ => None
      end
  | cast_case_s2f =>
      match v with
      | Vsingle f => Some (Vfloat (Float.of_single f))
      | _ => None
      end
  | cast_case_f2s =>
      match v with
      | Vfloat f => Some (Vsingle (Float.to_single f))
      | _ => None
      end
  | cast_case_i2f si1 =>
      match v with
      | Vint i => Some (Vfloat (cast_int_float si1 i))
      | _ => None
      end
  | cast_case_i2s si1 =>
      match v with
      | Vint i => Some (Vsingle (cast_int_single si1 i))
      | _ => None
      end
  | cast_case_f2i sz2 si2 =>
      match v with
      | Vfloat f =>
          match cast_float_int si2 f with
          | Some i => Some (Vint (cast_int_int sz2 si2 i))
          | None => None
          end
      | _ => None
      end
  | cast_case_s2i sz2 si2 =>
      match v with
      | Vsingle f =>
          match cast_single_int si2 f with
          | Some i => Some (Vint (cast_int_int sz2 si2 i))
          | None => None
          end
      | _ => None
      end
  | cast_case_f2bool =>
      match v with
      | Vfloat f =>
          Some(Vint(if Float.cmp Ceq f Float.zero then Int.zero else Int.one))
      | _ => None
      end
  | cast_case_s2bool =>
      match v with
      | Vsingle f =>
          Some(Vint(if Float32.cmp Ceq f Float32.zero then Int.zero else Int.one))
      | _ => None
      end
  | cast_case_p2bool =>
      match v with
      | Vint i => Some (Vint (cast_int_int IBool Signed i))
      | Vptr _ _ => Some (Vint Int.one)
      | _ => None
      end
  | cast_case_l2l =>
      match v with
      | Vlong n => Some (Vlong n)
      | _ => None
      end
  | cast_case_i2l si =>
      match v with
      | Vint n => Some(Vlong (cast_int_long si n))
      | _ => None
      end
  | cast_case_l2i sz si =>
      match v with
      | Vlong n => Some(Vint (cast_int_int sz si (Int.repr (Int64.unsigned n))))
      | _ => None
      end
  | cast_case_l2bool =>
      match v with
      | Vlong n =>
          Some(Vint(if Int64.eq n Int64.zero then Int.zero else Int.one))
      | _ => None
      end
  | cast_case_l2f si1 =>
      match v with
      | Vlong i => Some (Vfloat (cast_long_float si1 i))
      | _ => None
      end
  | cast_case_l2s si1 =>
      match v with
      | Vlong i => Some (Vsingle (cast_long_single si1 i))
      | _ => None
      end
  | cast_case_f2l si2 =>
      match v with
      | Vfloat f =>
          match cast_float_long si2 f with
          | Some i => Some (Vlong i)
          | None => None
          end
      | _ => None
      end
  | cast_case_s2l si2 =>
      match v with
      | Vsingle f =>
          match cast_single_long si2 f with
          | Some i => Some (Vlong i)
          | None => None
          end
      | _ => None
      end
  | cast_case_struct id1 fld1 id2 fld2 =>
      match v with
      | Vptr b ofs =>
          if ident_eq id1 id2 && fieldlist_eq fld1 fld2 then Some v else None
      | _ => None
      end
  | cast_case_union id1 fld1 id2 fld2 =>
      match v with
      | Vptr b ofs =>
          if ident_eq id1 id2 && fieldlist_eq fld1 fld2 then Some v else None
      | _ => None
      end
  | cast_case_void =>
      Some v
  | cast_case_default =>
      None
  end.

(** The following describes types that can be interpreted as a boolean:
  integers, floats, pointers.  It is used for the semantics of 
  the [!] and [?] operators, as well as the [if], [while], 
  and [for] statements. *)

Inductive classify_bool_cases : Type :=
  | bool_case_i                           (**r integer *)
  | bool_case_f                           (**r double float *)
  | bool_case_s                           (**r single float *)
  | bool_case_p                           (**r pointer *)
  | bool_case_l                           (**r long *)
  | bool_default.

Definition classify_bool (ty: type) : classify_bool_cases :=
  match typeconv ty with
  | Tint _ _ _ => bool_case_i
  | Tpointer _ _ | Tcomp_ptr _ _ => bool_case_p
  | Tfloat F64 _ => bool_case_f
  | Tfloat F32 _ => bool_case_s
  | Tlong _ _ => bool_case_l
  | _ => bool_default
  end.

(** Interpretation of values as truth values.
  Non-zero integers, non-zero floats and non-null pointers are
  considered as true.  The integer zero (which also represents
  the null pointer) and the float 0.0 are false. *)

Definition bool_val (v: val) (t: type) : option bool :=
  match classify_bool t with
  | bool_case_i =>
      match v with
      | Vint n => Some (negb (Int.eq n Int.zero))
      | _ => None
      end
  | bool_case_f =>
      match v with
      | Vfloat f => Some (negb (Float.cmp Ceq f Float.zero))
      | _ => None
      end
  | bool_case_s =>
      match v with
      | Vsingle f => Some (negb (Float32.cmp Ceq f Float32.zero))
      | _ => None
      end
  | bool_case_p =>
      match v with
      | Vint n => Some (negb (Int.eq n Int.zero))
      | Vptr b ofs => Some true
      | _ => None
      end
  | bool_case_l =>
      match v with
      | Vlong n => Some (negb (Int64.eq n Int64.zero))
      | _ => None
      end
  | bool_default => None
  end.


(** ** Unary operators *)

(** *** Boolean negation *)

Definition sem_notbool (v: val) (ty: type) : option val :=
  match classify_bool ty with
  | bool_case_i =>
      match v with
      | Vint n => Some (Val.of_bool (Int.eq n Int.zero))
      | _ => None
      end
  | bool_case_f =>
      match v with
      | Vfloat f => Some (Val.of_bool (Float.cmp Ceq f Float.zero))
      | _ => None
      end
  | bool_case_s =>
      match v with
      | Vsingle f => Some (Val.of_bool (Float32.cmp Ceq f Float32.zero))
      | _ => None
      end
  | bool_case_p =>
      match v with
      | Vint n => Some (Val.of_bool (Int.eq n Int.zero))
      | Vptr _ _ => Some Vfalse
      | _ => None
      end
  | bool_case_l =>
      match v with
      | Vlong n => Some (Val.of_bool (Int64.eq n Int64.zero))
      | _ => None
      end
  | bool_default => None
  end.

(** *** Opposite and absolute value *)

Inductive classify_neg_cases : Type :=
  | neg_case_i(s: signedness)              (**r int *)
  | neg_case_f                             (**r double float *)
  | neg_case_s                             (**r single float *)
  | neg_case_l(s: signedness)              (**r long *)
  | neg_default.

Definition classify_neg (ty: type) : classify_neg_cases :=
  match ty with
  | Tint I32 Unsigned _ => neg_case_i Unsigned
  | Tint _ _ _ => neg_case_i Signed
  | Tfloat F64 _ => neg_case_f
  | Tfloat F32 _ => neg_case_s
  | Tlong si _ => neg_case_l si
  | _ => neg_default
  end.

Definition sem_neg (v: val) (ty: type) : option val :=
  match classify_neg ty with
  | neg_case_i sg =>
      match v with
      | Vint n => Some (Vint (Int.neg n))
      | _ => None
      end
  | neg_case_f =>
      match v with
      | Vfloat f => Some (Vfloat (Float.neg f))
      | _ => None
      end
  | neg_case_s =>
      match v with
      | Vsingle f => Some (Vsingle (Float32.neg f))
      | _ => None
      end
  | neg_case_l sg =>
      match v with
      | Vlong n => Some (Vlong (Int64.neg n))
      | _ => None
      end
  | neg_default => None
  end.

Definition sem_absfloat (v: val) (ty: type) : option val :=
  match classify_neg ty with
  | neg_case_i sg =>
      match v with
      | Vint n => Some (Vfloat (Float.abs (cast_int_float sg n)))
      | _ => None
      end
  | neg_case_f =>
      match v with
      | Vfloat f => Some (Vfloat (Float.abs f))
      | _ => None
      end
  | neg_case_s =>
      match v with
      | Vsingle f => Some (Vfloat (Float.abs (Float.of_single f)))
      | _ => None
      end
  | neg_case_l sg =>
      match v with
      | Vlong n => Some (Vfloat (Float.abs (cast_long_float sg n)))
      | _ => None
      end
  | neg_default => None
  end.

(** *** Bitwise complement *)

Inductive classify_notint_cases : Type :=
  | notint_case_i(s: signedness)              (**r int *)
  | notint_case_l(s: signedness)              (**r long *)
  | notint_default.

Definition classify_notint (ty: type) : classify_notint_cases :=
  match ty with
  | Tint I32 Unsigned _ => notint_case_i Unsigned
  | Tint _ _ _ => notint_case_i Signed
  | Tlong si _ => notint_case_l si
  | _ => notint_default
  end.

Definition sem_notint (v: val) (ty: type): option val :=
  match classify_notint ty with
  | notint_case_i sg =>
      match v with
      | Vint n => Some (Vint (Int.not n))
      | _ => None
      end
  | notint_case_l sg =>
      match v with
      | Vlong n => Some (Vlong (Int64.not n))
      | _ => None
      end
  | notint_default => None
  end.

(** ** Binary operators *)

(** For binary operations, the "usual binary conversions" consist in
- determining the type at which the operation is to be performed
  (a form of least upper bound of the types of the two arguments);
- casting the two arguments to this common type;
- performing the operation at that type.
*)

Inductive binarith_cases: Type :=
  | bin_case_i (s: signedness)         (**r at int type *)
  | bin_case_l (s: signedness)         (**r at long int type *)
  | bin_case_f                         (**r at double float type *)
  | bin_case_s                         (**r at single float type *)
  | bin_default.                       (**r error *)

Definition classify_binarith (ty1: type) (ty2: type) : binarith_cases :=
  match ty1, ty2 with
  | Tint I32 Unsigned _, Tint _ _ _ => bin_case_i Unsigned
  | Tint _ _ _, Tint I32 Unsigned _ => bin_case_i Unsigned
  | Tint _ _ _, Tint _ _ _ => bin_case_i Signed
  | Tlong Signed _, Tlong Signed _ => bin_case_l Signed
  | Tlong _ _, Tlong _ _ => bin_case_l Unsigned
  | Tlong sg _, Tint _ _ _ => bin_case_l sg
  | Tint _ _ _, Tlong sg _ => bin_case_l sg
  | Tfloat F32 _, Tfloat F32 _ => bin_case_s
  | Tfloat _ _, Tfloat _ _ => bin_case_f
  | Tfloat F64 _, (Tint _ _ _ | Tlong _ _) => bin_case_f
  | (Tint _ _ _ | Tlong _ _), Tfloat F64 _ => bin_case_f
  | Tfloat F32 _, (Tint _ _ _ | Tlong _ _) => bin_case_s
  | (Tint _ _ _ | Tlong _ _), Tfloat F32 _ => bin_case_s
  | _, _ => bin_default
  end.

(** The static type of the result. Both arguments are converted to this type
    before the actual computation. *)

Definition binarith_type (c: binarith_cases) : type :=
  match c with
  | bin_case_i sg => Tint I32 sg noattr
  | bin_case_l sg => Tlong sg noattr
  | bin_case_f    => Tfloat F64 noattr
  | bin_case_s    => Tfloat F32 noattr
  | bin_default   => Tvoid
  end.

Definition sem_binarith
    (sem_int: signedness -> int -> int -> option val)
    (sem_long: signedness -> int64 -> int64 -> option val)
    (sem_float: float -> float -> option val)
    (sem_single: float32 -> float32 -> option val)
    (v1: val) (t1: type) (v2: val) (t2: type) : option val :=
  let c := classify_binarith t1 t2 in
  let t := binarith_type c in
  match sem_cast v1 t1 t with
  | None => None
  | Some v1' =>
  match sem_cast v2 t2 t with
  | None => None
  | Some v2' =>
  match c with
  | bin_case_i sg =>
      match v1', v2' with
      | Vint n1, Vint n2 => sem_int sg n1 n2
      | _,  _ => None
      end
  | bin_case_f =>
      match v1', v2' with
      | Vfloat n1, Vfloat n2 => sem_float n1 n2
      | _,  _ => None
      end
  | bin_case_s =>
      match v1', v2' with
      | Vsingle n1, Vsingle n2 => sem_single n1 n2
      | _,  _ => None
      end
  | bin_case_l sg =>
      match v1', v2' with
      | Vlong n1, Vlong n2 => sem_long sg n1 n2
      | _,  _ => None
      end
  | bin_default => None
  end end end.

(** *** Addition *)

Inductive classify_add_cases : Type :=
  | add_case_pi(ty: type)     (**r pointer, int *)
  | add_case_ip(ty: type)     (**r int, pointer *)
  | add_case_pl(ty: type)     (**r pointer, long *)
  | add_case_lp(ty: type)     (**r long, pointer *)
  | add_default.                       (**r numerical type, numerical type *)

Definition classify_add (ty1: type) (ty2: type) :=
  match typeconv ty1, typeconv ty2 with
  | Tpointer ty _, Tint _ _ _ => add_case_pi ty
  | Tint _ _ _, Tpointer ty _ => add_case_ip ty
  | Tpointer ty _, Tlong _ _ => add_case_pl ty
  | Tlong _ _, Tpointer ty _ => add_case_lp ty
  | _, _ => add_default
  end.

Definition sem_add (v1:val) (t1:type) (v2: val) (t2:type) : option val :=
  match classify_add t1 t2 with 
  | add_case_pi ty =>                 (**r pointer plus integer *)
      match v1,v2 with
      | Vptr b1 ofs1, Vint n2 => 
        Some (Vptr b1 (Int.add ofs1 (Int.mul (Int.repr (sizeof ty)) n2)))
      | _,  _ => None
      end   
  | add_case_ip ty =>                 (**r integer plus pointer *)
      match v1,v2 with
      | Vint n1, Vptr b2 ofs2 => 
        Some (Vptr b2 (Int.add ofs2 (Int.mul (Int.repr (sizeof ty)) n1)))
      | _,  _ => None
      end   
  | add_case_pl ty =>                 (**r pointer plus long *)
      match v1,v2 with
      | Vptr b1 ofs1, Vlong n2 => 
        let n2 := Int.repr (Int64.unsigned n2) in
        Some (Vptr b1 (Int.add ofs1 (Int.mul (Int.repr (sizeof ty)) n2)))
      | _,  _ => None
      end   
  | add_case_lp ty =>                 (**r long plus pointer *)
      match v1,v2 with
      | Vlong n1, Vptr b2 ofs2 => 
        let n1 := Int.repr (Int64.unsigned n1) in
        Some (Vptr b2 (Int.add ofs2 (Int.mul (Int.repr (sizeof ty)) n1)))
      | _,  _ => None
      end   
  | add_default =>
      sem_binarith
        (fun sg n1 n2 => Some(Vint(Int.add n1 n2)))
        (fun sg n1 n2 => Some(Vlong(Int64.add n1 n2)))
        (fun n1 n2 => Some(Vfloat(Float.add n1 n2)))
        (fun n1 n2 => Some(Vsingle(Float32.add n1 n2)))
        v1 t1 v2 t2
  end.

(** *** Subtraction *)

Inductive classify_sub_cases : Type :=
  | sub_case_pi(ty: type)               (**r pointer, int *)
  | sub_case_pp(ty: type)               (**r pointer, pointer *)
  | sub_case_pl(ty: type)               (**r pointer, long *)
  | sub_default.                        (**r numerical type, numerical type *)

Definition classify_sub (ty1: type) (ty2: type) :=
  match typeconv ty1, typeconv ty2 with
  | Tpointer ty _, Tint _ _ _ => sub_case_pi ty
  | Tpointer ty _ , Tpointer _ _ => sub_case_pp ty
  | Tpointer ty _, Tlong _ _ => sub_case_pl ty
  | _, _ => sub_default
  end.

Definition sem_sub (v1:val) (t1:type) (v2: val) (t2:type) : option val :=
  match classify_sub t1 t2 with
  | sub_case_pi ty =>            (**r pointer minus integer *)
      match v1,v2 with
      | Vptr b1 ofs1, Vint n2 => 
          Some (Vptr b1 (Int.sub ofs1 (Int.mul (Int.repr (sizeof ty)) n2)))
      | _,  _ => None
      end
  | sub_case_pl ty =>            (**r pointer minus long *)
      match v1,v2 with
      | Vptr b1 ofs1, Vlong n2 => 
          let n2 := Int.repr (Int64.unsigned n2) in
          Some (Vptr b1 (Int.sub ofs1 (Int.mul (Int.repr (sizeof ty)) n2)))
      | _,  _ => None
      end
  | sub_case_pp ty =>          (**r pointer minus pointer *)
      match v1,v2 with
      | Vptr b1 ofs1, Vptr b2 ofs2 =>
          if eq_block b1 b2 then
            if Int.eq (Int.repr (sizeof ty)) Int.zero then None
            else Some (Vint (Int.divu (Int.sub ofs1 ofs2) (Int.repr (sizeof ty))))
          else None
      | _, _ => None
      end
  | sub_default =>
      sem_binarith
        (fun sg n1 n2 => Some(Vint(Int.sub n1 n2)))
        (fun sg n1 n2 => Some(Vlong(Int64.sub n1 n2)))
        (fun n1 n2 => Some(Vfloat(Float.sub n1 n2)))
        (fun n1 n2 => Some(Vsingle(Float32.sub n1 n2)))
        v1 t1 v2 t2
  end.
 
(** *** Multiplication, division, modulus *)

Definition sem_mul (v1:val) (t1:type) (v2: val) (t2:type) : option val :=
  sem_binarith
    (fun sg n1 n2 => Some(Vint(Int.mul n1 n2)))
    (fun sg n1 n2 => Some(Vlong(Int64.mul n1 n2)))
    (fun n1 n2 => Some(Vfloat(Float.mul n1 n2)))
    (fun n1 n2 => Some(Vsingle(Float32.mul n1 n2)))
    v1 t1 v2 t2.

Definition sem_div (v1:val) (t1:type) (v2: val) (t2:type) : option val :=
  sem_binarith
    (fun sg n1 n2 =>
      match sg with
      | Signed =>
          if Int.eq n2 Int.zero
          || Int.eq n1 (Int.repr Int.min_signed) && Int.eq n2 Int.mone
          then None else Some(Vint(Int.divs n1 n2))
      | Unsigned =>
          if Int.eq n2 Int.zero
          then None else Some(Vint(Int.divu n1 n2))
      end)
    (fun sg n1 n2 =>
      match sg with
      | Signed =>
          if Int64.eq n2 Int64.zero
          || Int64.eq n1 (Int64.repr Int64.min_signed) && Int64.eq n2 Int64.mone
          then None else Some(Vlong(Int64.divs n1 n2))
      | Unsigned =>
          if Int64.eq n2 Int64.zero
          then None else Some(Vlong(Int64.divu n1 n2))
      end)
    (fun n1 n2 => Some(Vfloat(Float.div n1 n2)))
    (fun n1 n2 => Some(Vsingle(Float32.div n1 n2)))
    v1 t1 v2 t2.

Definition sem_mod (v1:val) (t1:type) (v2: val) (t2:type) : option val :=
  sem_binarith
    (fun sg n1 n2 =>
      match sg with
      | Signed =>
          if Int.eq n2 Int.zero
          || Int.eq n1 (Int.repr Int.min_signed) && Int.eq n2 Int.mone
          then None else Some(Vint(Int.mods n1 n2))
      | Unsigned =>
          if Int.eq n2 Int.zero
          then None else Some(Vint(Int.modu n1 n2))
      end)
    (fun sg n1 n2 =>
      match sg with
      | Signed =>
          if Int64.eq n2 Int64.zero
          || Int64.eq n1 (Int64.repr Int64.min_signed) && Int64.eq n2 Int64.mone
          then None else Some(Vlong(Int64.mods n1 n2))
      | Unsigned =>
          if Int64.eq n2 Int64.zero
          then None else Some(Vlong(Int64.modu n1 n2))
      end)
    (fun n1 n2 => None)
    (fun n1 n2 => None)
    v1 t1 v2 t2.

Definition sem_and (v1:val) (t1:type) (v2: val) (t2:type) : option val :=
  sem_binarith
    (fun sg n1 n2 => Some(Vint(Int.and n1 n2)))
    (fun sg n1 n2 => Some(Vlong(Int64.and n1 n2)))
    (fun n1 n2 => None)
    (fun n1 n2 => None)
    v1 t1 v2 t2.

Definition sem_or (v1:val) (t1:type) (v2: val) (t2:type) : option val :=
  sem_binarith
    (fun sg n1 n2 => Some(Vint(Int.or n1 n2)))
    (fun sg n1 n2 => Some(Vlong(Int64.or n1 n2)))
    (fun n1 n2 => None)
    (fun n1 n2 => None)
    v1 t1 v2 t2.

Definition sem_xor (v1:val) (t1:type) (v2: val) (t2:type) : option val :=
  sem_binarith
    (fun sg n1 n2 => Some(Vint(Int.xor n1 n2)))
    (fun sg n1 n2 => Some(Vlong(Int64.xor n1 n2)))
    (fun n1 n2 => None)
    (fun n1 n2 => None)
    v1 t1 v2 t2.

(** *** Shifts *)

(** Shifts do not perform the usual binary conversions.  Instead,
  each argument is converted independently, and the signedness
  of the result is always that of the first argument. *)

Inductive classify_shift_cases : Type:=
  | shift_case_ii(s: signedness)         (**r int , int *)
  | shift_case_ll(s: signedness)         (**r long, long *)
  | shift_case_il(s: signedness)         (**r int, long *)
  | shift_case_li(s: signedness)         (**r long, int *)
  | shift_default.

Definition classify_shift (ty1: type) (ty2: type) :=
  match typeconv ty1, typeconv ty2 with
  | Tint I32 Unsigned _, Tint _ _ _ => shift_case_ii Unsigned
  | Tint _ _ _, Tint _ _ _ => shift_case_ii Signed
  | Tint I32 Unsigned _, Tlong _ _ => shift_case_il Unsigned
  | Tint _ _ _, Tlong _ _ => shift_case_il Signed
  | Tlong s _, Tint _ _ _ => shift_case_li s
  | Tlong s _, Tlong _ _ => shift_case_ll s
  | _,_  => shift_default
  end.

Definition sem_shift
    (sem_int: signedness -> int -> int -> int)
    (sem_long: signedness -> int64 -> int64 -> int64)
    (v1: val) (t1: type) (v2: val) (t2: type) : option val :=
  match classify_shift t1 t2 with
  | shift_case_ii sg =>
      match v1, v2 with
      | Vint n1, Vint n2 => 
          if Int.ltu n2 Int.iwordsize
          then Some(Vint(sem_int sg n1 n2)) else None
      | _, _ => None
      end
  | shift_case_il sg =>
      match v1, v2 with
      | Vint n1, Vlong n2 => 
          if Int64.ltu n2 (Int64.repr 32)
          then Some(Vint(sem_int sg n1 (Int64.loword n2))) else None
      | _, _ => None
      end
  | shift_case_li sg =>
      match v1, v2 with
      | Vlong n1, Vint n2 => 
          if Int.ltu n2 Int64.iwordsize'
          then Some(Vlong(sem_long sg n1 (Int64.repr (Int.unsigned n2)))) else None
      | _, _ => None
      end
  | shift_case_ll sg =>
      match v1, v2 with
      | Vlong n1, Vlong n2 => 
          if Int64.ltu n2 Int64.iwordsize
          then Some(Vlong(sem_long sg n1 n2)) else None
      | _, _ => None
      end
  | shift_default => None
  end.

Definition sem_shl (v1:val) (t1:type) (v2: val) (t2:type) : option val :=
  sem_shift
    (fun sg n1 n2 => Int.shl n1 n2)
    (fun sg n1 n2 => Int64.shl n1 n2)
    v1 t1 v2 t2.

Definition sem_shr (v1:val) (t1:type) (v2: val) (t2:type) : option val :=
  sem_shift
    (fun sg n1 n2 => match sg with Signed => Int.shr n1 n2 | Unsigned => Int.shru n1 n2 end)
    (fun sg n1 n2 => match sg with Signed => Int64.shr n1 n2 | Unsigned => Int64.shru n1 n2 end)
    v1 t1 v2 t2.

(** *** Comparisons *)

Inductive classify_cmp_cases : Type :=
  | cmp_case_pp                       (**r pointer, pointer *)
  | cmp_case_pl                       (**r pointer, long *)
  | cmp_case_lp                       (**r long, pointer *)
  | cmp_default.                      (**r numerical, numerical *)

Definition classify_cmp (ty1: type) (ty2: type) :=
  match typeconv ty1, typeconv ty2 with 
  | Tpointer _ _ , Tpointer _ _ => cmp_case_pp
  | Tpointer _ _ , Tint _ _ _ => cmp_case_pp
  | Tint _ _ _, Tpointer _ _ => cmp_case_pp
  | Tpointer _ _ , Tlong _ _ => cmp_case_pl
  | Tlong _ _ , Tpointer _ _ => cmp_case_lp
  | _, _ => cmp_default
  end.

Definition sem_cmp (c:comparison)
                  (v1: val) (t1: type) (v2: val) (t2: type)
                  (m: mem): option val :=
  match classify_cmp t1 t2 with
  | cmp_case_pp =>
      option_map Val.of_bool (Val.cmpu_bool (Mem.valid_pointer m) c v1 v2)
  | cmp_case_pl =>
      match v2 with
      | Vlong n2 => 
          let n2 := Int.repr (Int64.unsigned n2) in
          option_map Val.of_bool (Val.cmpu_bool (Mem.valid_pointer m) c v1 (Vint n2))
      | _ => None
      end
  | cmp_case_lp =>
      match v1 with
      | Vlong n1 => 
          let n1 := Int.repr (Int64.unsigned n1) in
          option_map Val.of_bool (Val.cmpu_bool (Mem.valid_pointer m) c (Vint n1) v2)
      | _ => None
      end
  | cmp_default =>
      sem_binarith
        (fun sg n1 n2 =>
            Some(Val.of_bool(match sg with Signed => Int.cmp c n1 n2 | Unsigned => Int.cmpu c n1 n2 end)))
        (fun sg n1 n2 =>
            Some(Val.of_bool(match sg with Signed => Int64.cmp c n1 n2 | Unsigned => Int64.cmpu c n1 n2 end)))
        (fun n1 n2 =>
            Some(Val.of_bool(Float.cmp c n1 n2)))
        (fun n1 n2 =>
            Some(Val.of_bool(Float32.cmp c n1 n2)))
        v1 t1 v2 t2
  end.

(** ** Function applications *)

Inductive classify_fun_cases : Type :=
  | fun_case_f (targs: typelist) (tres: type) (cc: calling_convention) (**r (pointer to) function *)
  | fun_default.

Definition classify_fun (ty: type) :=
  match ty with 
  | Tfunction args res cc => fun_case_f args res cc
  | Tpointer (Tfunction args res cc) _ => fun_case_f args res cc
  | _ => fun_default
  end.

(** ** Argument of a [switch] statement *)

Inductive classify_switch_cases : Type :=
  | switch_case_i
  | switch_case_l
  | switch_default.

Definition classify_switch (ty: type) :=
  match ty with
  | Tint _ _ _ => switch_case_i
  | Tlong _ _ => switch_case_l
  | _ => switch_default
  end.

Definition sem_switch_arg (v: val) (ty: type): option Z :=
  match classify_switch ty with
  | switch_case_i =>
      match v with Vint n => Some(Int.unsigned n) | _ => None end
  | switch_case_l =>
      match v with Vlong n => Some(Int64.unsigned n) | _ => None end
  | switch_default =>
      None
  end.

(** * Combined semantics of unary and binary operators *)

Definition sem_unary_operation
            (op: unary_operation) (v: val) (ty: type): option val :=
  match op with
  | Onotbool => sem_notbool v ty
  | Onotint => sem_notint v ty
  | Oneg => sem_neg v ty
  | Oabsfloat => sem_absfloat v ty
  end.

Definition sem_binary_operation
    (op: binary_operation)
    (v1: val) (t1: type) (v2: val) (t2:type)
    (m: mem): option val :=
  match op with
  | Oadd => sem_add v1 t1 v2 t2
  | Osub => sem_sub v1 t1 v2 t2 
  | Omul => sem_mul v1 t1 v2 t2
  | Omod => sem_mod v1 t1 v2 t2
  | Odiv => sem_div v1 t1 v2 t2 
  | Oand => sem_and v1 t1 v2 t2
  | Oor  => sem_or v1 t1 v2 t2
  | Oxor  => sem_xor v1 t1 v2 t2
  | Oshl => sem_shl v1 t1 v2 t2
  | Oshr  => sem_shr v1 t1 v2 t2   
  | Oeq => sem_cmp Ceq v1 t1 v2 t2 m
  | One => sem_cmp Cne v1 t1 v2 t2 m
  | Olt => sem_cmp Clt v1 t1 v2 t2 m
  | Ogt => sem_cmp Cgt v1 t1 v2 t2 m
  | Ole => sem_cmp Cle v1 t1 v2 t2 m
  | Oge => sem_cmp Cge v1 t1 v2 t2 m
  end.

Definition sem_incrdecr (id: incr_or_decr) (v: val) (ty: type) :=
  match id with
  | Incr => sem_add v ty (Vint Int.one) type_int32s
  | Decr => sem_sub v ty (Vint Int.one) type_int32s
  end.

Definition incrdecr_type (ty: type) :=
  match typeconv ty with
  | Tpointer ty a => Tpointer ty a
  | Tint sz sg a => Tint sz sg noattr
  | Tlong sg a => Tlong sg noattr
  | Tfloat sz a => Tfloat sz noattr
  | _ => Tvoid
  end.

(** * Compatibility with extensions and injections *)

Section GENERIC_INJECTION.

Variable f: meminj.
Variables m m': mem.

Hypothesis valid_pointer_inj:
  forall b1 ofs b2 delta,
  f b1 = Some(b2, delta) ->
  Mem.valid_pointer m b1 (Int.unsigned ofs) = true ->
  Mem.valid_pointer m' b2 (Int.unsigned (Int.add ofs (Int.repr delta))) = true.

Hypothesis weak_valid_pointer_inj:
  forall b1 ofs b2 delta,
  f b1 = Some(b2, delta) ->
  Mem.weak_valid_pointer m b1 (Int.unsigned ofs) = true ->
  Mem.weak_valid_pointer m' b2 (Int.unsigned (Int.add ofs (Int.repr delta))) = true.

Hypothesis weak_valid_pointer_no_overflow:
  forall b1 ofs b2 delta,
  f b1 = Some(b2, delta) ->
  Mem.weak_valid_pointer m b1 (Int.unsigned ofs) = true ->
  0 <= Int.unsigned ofs + Int.unsigned (Int.repr delta) <= Int.max_unsigned.

Hypothesis valid_different_pointers_inj:
  forall b1 ofs1 b2 ofs2 b1' delta1 b2' delta2,
  b1 <> b2 ->
  Mem.valid_pointer m b1 (Int.unsigned ofs1) = true ->
  Mem.valid_pointer m b2 (Int.unsigned ofs2) = true ->
  f b1 = Some (b1', delta1) ->
  f b2 = Some (b2', delta2) ->
  b1' <> b2' \/
  Int.unsigned (Int.add ofs1 (Int.repr delta1)) <> Int.unsigned (Int.add ofs2 (Int.repr delta2)).

Remark val_inject_vtrue: forall f, val_inject f Vtrue Vtrue.
Proof. unfold Vtrue; auto. Qed.

Remark val_inject_vfalse: forall f, val_inject f Vfalse Vfalse.
Proof. unfold Vfalse; auto. Qed.

Remark val_inject_of_bool: forall f b, val_inject f (Val.of_bool b) (Val.of_bool b).
Proof. intros. unfold Val.of_bool. destruct b; [apply val_inject_vtrue|apply val_inject_vfalse]. 
Qed.

Hint Resolve val_inject_vtrue val_inject_vfalse val_inject_of_bool.

Ltac TrivialInject :=
  match goal with
  | |- exists v', Some ?v = Some v' /\ _ => exists v; split; auto
  | _ => idtac
  end.

Lemma sem_cast_inject:
  forall v1 ty1 ty v tv1,
  sem_cast v1 ty1 ty = Some v ->
  val_inject f v1 tv1 ->
  exists tv, sem_cast tv1 ty1 ty = Some tv /\ val_inject f v tv.
Proof.
  unfold sem_cast; intros; destruct (classify_cast ty1 ty);
  inv H0; inv H; TrivialInject.
- econstructor; eauto. 
- destruct (cast_float_int si2 f0); inv H1; TrivialInject.
- destruct (cast_single_int si2 f0); inv H1; TrivialInject.
- destruct (cast_float_long si2 f0); inv H1; TrivialInject.
- destruct (cast_single_long si2 f0); inv H1; TrivialInject.
- destruct (ident_eq id1 id2 && fieldlist_eq fld1 fld2); inv H2; TrivialInject. econstructor; eauto.
- destruct (ident_eq id1 id2 && fieldlist_eq fld1 fld2); inv H2; TrivialInject. econstructor; eauto.
- econstructor; eauto.
Qed.

Lemma sem_unary_operation_inject:
  forall op v1 ty v tv1,
  sem_unary_operation op v1 ty = Some v ->
  val_inject f v1 tv1 ->
  exists tv, sem_unary_operation op tv1 ty = Some tv /\ val_inject f v tv.
Proof.
  unfold sem_unary_operation; intros. destruct op.
  (* notbool *)
  unfold sem_notbool in *; destruct (classify_bool ty); inv H0; inv H; TrivialInject.
  (* notint *)
  unfold sem_notint in *; destruct (classify_notint ty); inv H0; inv H; TrivialInject.
  (* neg *)
  unfold sem_neg in *; destruct (classify_neg ty); inv H0; inv H; TrivialInject.
  (* absfloat *)
  unfold sem_absfloat in *; destruct (classify_neg ty); inv H0; inv H; TrivialInject.
Qed.

Definition optval_self_injects (ov: option val) : Prop :=
  match ov with
  | Some (Vptr b ofs) => False
  | _ => True
  end.

Remark sem_binarith_inject:
  forall sem_int sem_long sem_float sem_single v1 t1 v2 t2 v v1' v2',
  sem_binarith sem_int sem_long sem_float sem_single v1 t1 v2 t2 = Some v ->
  val_inject f v1 v1' -> val_inject f v2 v2' ->
  (forall sg n1 n2, optval_self_injects (sem_int sg n1 n2)) ->
  (forall sg n1 n2, optval_self_injects (sem_long sg n1 n2)) ->
  (forall n1 n2, optval_self_injects (sem_float n1 n2)) ->
  (forall n1 n2, optval_self_injects (sem_single n1 n2)) ->
  exists v', sem_binarith sem_int sem_long sem_float sem_single v1' t1 v2' t2 = Some v' /\ val_inject f v v'.
Proof.
  intros. 
  assert (SELF: forall ov v, ov = Some v -> optval_self_injects ov -> val_inject f v v).
  {
    intros. subst ov; simpl in H7. destruct v0; contradiction || constructor.
  }
  unfold sem_binarith in *.
  set (c := classify_binarith t1 t2) in *.
  set (t := binarith_type c) in *.
  destruct (sem_cast v1 t1 t) as [w1|] eqn:C1; try discriminate.
  destruct (sem_cast v2 t2 t) as [w2|] eqn:C2; try discriminate.
  exploit (sem_cast_inject v1); eauto. intros (w1' & C1' & INJ1).
  exploit (sem_cast_inject v2); eauto. intros (w2' & C2' & INJ2).
  rewrite C1'; rewrite C2'.
  destruct c; inv INJ1; inv INJ2; discriminate || eauto.
Qed.

Remark sem_shift_inject:
  forall sem_int sem_long v1 t1 v2 t2 v v1' v2',
  sem_shift sem_int sem_long v1 t1 v2 t2 = Some v ->
  val_inject f v1 v1' -> val_inject f v2 v2' ->
  exists v', sem_shift sem_int sem_long v1' t1 v2' t2 = Some v' /\ val_inject f v v'.
Proof.
  intros. exists v.
  unfold sem_shift in *; destruct (classify_shift t1 t2); inv H0; inv H1; try discriminate.
  destruct (Int.ltu i0 Int.iwordsize); inv H; auto.
  destruct (Int64.ltu i0 Int64.iwordsize); inv H; auto.
  destruct (Int64.ltu i0 (Int64.repr 32)); inv H; auto.
  destruct (Int.ltu i0 Int64.iwordsize'); inv H; auto.
Qed.

Remark sem_cmp_inj:
  forall cmp v1 tv1 ty1 v2 tv2 ty2 v,
  sem_cmp cmp v1 ty1 v2 ty2 m = Some v ->
  val_inject f v1 tv1 ->
  val_inject f v2 tv2 ->
  exists tv, sem_cmp cmp tv1 ty1 tv2 ty2 m' = Some tv /\ val_inject f v tv.
Proof.
  intros.
  unfold sem_cmp in *; destruct (classify_cmp ty1 ty2).
- (* pointer - pointer *)
  destruct (Val.cmpu_bool (Mem.valid_pointer m) cmp v1 v2) as [b|] eqn:E; simpl in H; inv H.
  replace (Val.cmpu_bool (Mem.valid_pointer m') cmp tv1 tv2) with (Some b).
  simpl. TrivialInject. 
  symmetry. eapply val_cmpu_bool_inject; eauto. 
- (* pointer - long *)
  destruct v2; try discriminate. inv H1. 
  set (v2 := Vint (Int.repr (Int64.unsigned i))) in *.
  destruct (Val.cmpu_bool (Mem.valid_pointer m) cmp v1 v2) as [b|] eqn:E; simpl in H; inv H.
  replace (Val.cmpu_bool (Mem.valid_pointer m') cmp tv1 v2) with (Some b).
  simpl. TrivialInject. 
  symmetry. eapply val_cmpu_bool_inject with (v2 := v2); eauto. constructor. 
- (* long - pointer *)
  destruct v1; try discriminate. inv H0. 
  set (v1 := Vint (Int.repr (Int64.unsigned i))) in *.
  destruct (Val.cmpu_bool (Mem.valid_pointer m) cmp v1 v2) as [b|] eqn:E; simpl in H; inv H.
  replace (Val.cmpu_bool (Mem.valid_pointer m') cmp v1 tv2) with (Some b).
  simpl. TrivialInject. 
  symmetry. eapply val_cmpu_bool_inject with (v1 := v1); eauto. constructor. 
- (* numerical - numerical *)
  assert (SELF: forall b, optval_self_injects (Some (Val.of_bool b))).
  {
    destruct b; exact I.
  }
  eapply sem_binarith_inject; eauto.
Qed.

Lemma sem_binary_operation_inj:
  forall op v1 ty1 v2 ty2 v tv1 tv2,
  sem_binary_operation op v1 ty1 v2 ty2 m = Some v ->
  val_inject f v1 tv1 -> val_inject f v2 tv2 ->
  exists tv, sem_binary_operation op tv1 ty1 tv2 ty2 m' = Some tv /\ val_inject f v tv.
Proof.
  unfold sem_binary_operation; intros; destruct op.
- (* add *)
  unfold sem_add in *; destruct (classify_add ty1 ty2).
  + inv H0; inv H1; inv H. TrivialInject. 
    econstructor. eauto. repeat rewrite Int.add_assoc. decEq. apply Int.add_commut.
  + inv H0; inv H1; inv H. TrivialInject. 
    econstructor. eauto. repeat rewrite Int.add_assoc. decEq. apply Int.add_commut.
  + inv H0; inv H1; inv H. TrivialInject. 
    econstructor. eauto. repeat rewrite Int.add_assoc. decEq. apply Int.add_commut.
  + inv H0; inv H1; inv H. TrivialInject. 
    econstructor. eauto. repeat rewrite Int.add_assoc. decEq. apply Int.add_commut.
  + eapply sem_binarith_inject; eauto; intros; exact I.
- (* sub *)
  unfold sem_sub in *; destruct (classify_sub ty1 ty2).
  + inv H0; inv H1; inv H. TrivialInject.
    econstructor. eauto. rewrite Int.sub_add_l. auto.
  + inv H0; inv H1; inv H. TrivialInject.
    destruct (eq_block b1 b0); try discriminate. subst b1. 
    rewrite H0 in H2; inv H2. rewrite dec_eq_true. 
    destruct (Int.eq (Int.repr (sizeof ty)) Int.zero); inv H3.
    rewrite Int.sub_shifted. TrivialInject.
  + inv H0; inv H1; inv H. TrivialInject.
    econstructor. eauto. rewrite Int.sub_add_l. auto.
  + eapply sem_binarith_inject; eauto; intros; exact I.
- (* mul *)
  eapply sem_binarith_inject; eauto; intros; exact I.
- (* div *)
  eapply sem_binarith_inject; eauto; intros.
  destruct sg.
  destruct (Int.eq n2 Int.zero
            || Int.eq n1 (Int.repr Int.min_signed) && Int.eq n2 Int.mone); exact I.
  destruct (Int.eq n2 Int.zero); exact I.
  destruct sg.
  destruct (Int64.eq n2 Int64.zero
            || Int64.eq n1 (Int64.repr Int64.min_signed) && Int64.eq n2 Int64.mone); exact I.
  destruct (Int64.eq n2 Int64.zero); exact I.
  exact I.
  exact I.
- (* mod *)
  eapply sem_binarith_inject; eauto; intros.
  destruct sg.
  destruct (Int.eq n2 Int.zero
            || Int.eq n1 (Int.repr Int.min_signed) && Int.eq n2 Int.mone); exact I.
  destruct (Int.eq n2 Int.zero); exact I.
  destruct sg.
  destruct (Int64.eq n2 Int64.zero
            || Int64.eq n1 (Int64.repr Int64.min_signed) && Int64.eq n2 Int64.mone); exact I.
  destruct (Int64.eq n2 Int64.zero); exact I.
  exact I.
  exact I.
- (* and *)
  eapply sem_binarith_inject; eauto; intros; exact I.
- (* or *)
  eapply sem_binarith_inject; eauto; intros; exact I.
- (* xor *)
  eapply sem_binarith_inject; eauto; intros; exact I.
- (* shl *)
  eapply sem_shift_inject; eauto.
- (* shr *)
  eapply sem_shift_inject; eauto.
  (* comparisons *)
- eapply sem_cmp_inj; eauto.
- eapply sem_cmp_inj; eauto.
- eapply sem_cmp_inj; eauto.
- eapply sem_cmp_inj; eauto.
- eapply sem_cmp_inj; eauto.
- eapply sem_cmp_inj; eauto.
Qed.

Lemma bool_val_inject:
  forall v ty b tv,
  bool_val v ty = Some b ->
  val_inject f v tv ->
  bool_val tv ty = Some b.
Proof.
  unfold bool_val; intros. 
  destruct (classify_bool ty); inv H0; congruence.
Qed.

End GENERIC_INJECTION.

Lemma sem_binary_operation_inject:
  forall f m m' op v1 ty1 v2 ty2 v tv1 tv2,
  sem_binary_operation op v1 ty1 v2 ty2 m = Some v ->
  val_inject f v1 tv1 -> val_inject f v2 tv2 ->
  Mem.inject f m m' ->
  exists tv, sem_binary_operation op tv1 ty1 tv2 ty2 m' = Some tv /\ val_inject f v tv.
Proof.
  intros. eapply sem_binary_operation_inj; eauto. 
  intros; eapply Mem.valid_pointer_inject_val; eauto.
  intros; eapply Mem.weak_valid_pointer_inject_val; eauto.
  intros; eapply Mem.weak_valid_pointer_inject_no_overflow; eauto.
  intros; eapply Mem.different_pointers_inject; eauto.
Qed.

(** * Some properties of operator semantics *)

(** This section collects some common-sense properties about the type
  classification and semantic functions above.  These properties are
  not used in the CompCert semantics preservation proofs, but increase
  confidence in the specification and its relation with the ISO C99 standard. *)

(** Relation between Boolean value and casting to [_Bool] type. *)

Lemma cast_bool_bool_val:
  forall v t,
  sem_cast v t (Tint IBool Signed noattr) =
  match bool_val v t with None => None | Some b => Some(Val.of_bool b) end.
Proof.
  intros.
  assert (A: classify_bool t =
    match t with
    | Tint _ _ _ => bool_case_i
    | Tpointer _ _ | Tcomp_ptr _ _ | Tarray _ _ _ | Tfunction _ _ _ => bool_case_p
    | Tfloat F64 _ => bool_case_f
    | Tfloat F32 _ => bool_case_s
    | Tlong _ _ => bool_case_l
    | _ => bool_default
    end).
  {
    unfold classify_bool; destruct t; simpl; auto. destruct i; auto.
  }
  unfold bool_val. rewrite A. unfold sem_cast. destruct t; simpl; auto; destruct v; auto.
  destruct (Int.eq i0 Int.zero); auto.
  destruct (Int64.eq i Int64.zero); auto.
  destruct f; auto.
  destruct f; auto.
  destruct f; auto.
  destruct f; auto.
  destruct (Float.cmp Ceq f0 Float.zero); auto.
  destruct f; auto.
  destruct (Float32.cmp Ceq f0 Float32.zero); auto.
  destruct f; auto.
  destruct (Int.eq i Int.zero); auto. 
  destruct (Int.eq i Int.zero); auto. 
  destruct (Int.eq i Int.zero); auto. 
  destruct (Int.eq i0 Int.zero); auto. 
Qed.

(** Relation between Boolean value and Boolean negation. *)

Lemma notbool_bool_val:
  forall v t,
  sem_notbool v t =
  match bool_val v t with None => None | Some b => Some(Val.of_bool (negb b)) end.
Proof.
  intros. unfold sem_notbool, bool_val. 
  destruct (classify_bool t); auto; destruct v; auto; rewrite negb_involutive; auto.
Qed.

(** Relation with the arithmetic conversions of ISO C99, section 6.3.1 *)

Module ArithConv.

(** This is the ISO C algebra of arithmetic types, without qualifiers.
    [S] stands for "signed" and [U] for "unsigned".  *)

Inductive int_type : Type :=
  | _Bool
  | Char | SChar | UChar
  | Short | UShort
  | Int | UInt
  | Long | ULong
  | Longlong | ULonglong.

Inductive arith_type : Type :=
  | I (it: int_type)
  | Float
  | Double
  | Longdouble.

Definition eq_int_type: forall (x y: int_type), {x=y} + {x<>y}.
Proof. decide equality. Defined.

Definition is_unsigned (t: int_type) : bool :=
  match t with
  | _Bool => true
  | Char => false    (**r as in most of CompCert's target ABIs *)
  | SChar => false
  | UChar => true
  | Short => false
  | UShort => true
  | Int => false
  | UInt => true
  | Long => false
  | ULong => true
  | Longlong => false
  | ULonglong => true
  end.

Definition unsigned_type (t: int_type) : int_type :=
  match t with
  | Char => UChar
  | SChar => UChar
  | Short => UShort
  | Int => UInt
  | Long => ULong
  | Longlong => ULonglong
  | _ => t
  end.

Definition int_sizeof (t: int_type) : Z :=
  match t with
  | _Bool | Char | SChar | UChar => 1
  | Short | UShort => 2
  | Int | UInt | Long | ULong => 4
  | Longlong | ULonglong => 8
  end.

(** 6.3.1.1 para 1: integer conversion rank *)

Definition rank (t: int_type) : Z :=
  match t with
  | _Bool => 1
  | Char | SChar | UChar => 2
  | Short | UShort => 3
  | Int | UInt => 4
  | Long | ULong => 5
  | Longlong | ULonglong => 6
  end.

(** 6.3.1.1 para 2: integer promotions, a.k.a. usual unary conversions *)

Definition integer_promotion (t: int_type) : int_type :=
  if zlt (rank t) (rank Int) then Int else t.

(** 6.3.1.8: Usual arithmetic conversions, a.k.a. binary conversions.
  This function returns the type to which the two operands must be
  converted. *)

Definition usual_arithmetic_conversion (t1 t2: arith_type) : arith_type :=
  match t1, t2 with
  (* First, if the corresponding real type of either operand is long
     double, the other operand is converted, without change of type domain,
     to a type whose corresponding real type is long double. *)
  | Longdouble, _ | _, Longdouble => Longdouble
  (* Otherwise, if the corresponding real type of either operand is
     double, the other operand is converted, without change of type domain,
     to a type whose corresponding real type is double. *)
  | Double, _ | _, Double => Double
  (* Otherwise, if the corresponding real type of either operand is
     float, the other operand is converted, without change of type domain,
     to a type whose corresponding real type is float. *)
  | Float, _ | _, Float => Float
  (* Otherwise, the integer promotions are performed on both operands. *)
  | I i1, I i2 =>
    let j1 := integer_promotion i1 in
    let j2 := integer_promotion i2 in
    (* Then the following rules are applied to the promoted operands:
       If both operands have the same type, then no further conversion
       is needed. *)
    if eq_int_type j1 j2 then I j1 else
    match is_unsigned j1, is_unsigned j2 with
    (* Otherwise, if both operands have signed integer types or both
       have unsigned integer types, the operand with the type of lesser
       integer conversion rank is converted to the type of the operand with
       greater rank. *)
    | true, true | false, false =>
        if zlt (rank j1) (rank j2) then I j2 else I j1
    | true, false =>
    (* Otherwise, if the operand that has unsigned integer type has
       rank greater or equal to the rank of the type of the other operand,
       then the operand with signed integer type is converted to the type of
       the operand with unsigned integer type. *)
        if zle (rank j2) (rank j1) then I j1 else
    (* Otherwise, if the type of the operand with signed integer type
       can represent all of the values of the type of the operand with
       unsigned integer type, then the operand with unsigned integer type is
       converted to the type of the operand with signed integer type. *)
        if zlt (int_sizeof j1) (int_sizeof j2) then I j2 else
    (* Otherwise, both operands are converted to the unsigned integer type
       corresponding to the type of the operand with signed integer type. *)
        I (unsigned_type j2)
    | false, true =>
    (* Same logic as above, swapping the roles of j1 and j2 *)
        if zle (rank j1) (rank j2) then I j2 else
        if zlt (int_sizeof j2) (int_sizeof j1) then I j1 else
        I (unsigned_type j1)
    end
  end.

(** Mapping ISO arithmetic types to CompCert types *)

Definition proj_type (t: arith_type) : type :=
  match t with
  | I _Bool => Tint IBool Unsigned noattr
  | I Char => Tint I8 Unsigned noattr
  | I SChar => Tint I8 Signed noattr
  | I UChar => Tint I8 Unsigned noattr
  | I Short => Tint I16 Signed noattr
  | I UShort => Tint I16 Unsigned noattr
  | I Int => Tint I32 Signed noattr
  | I UInt => Tint I32 Unsigned noattr
  | I Long => Tint I32 Signed noattr
  | I ULong => Tint I32 Unsigned noattr
  | I Longlong => Tlong Signed noattr
  | I ULonglong => Tlong Unsigned noattr
  | Float => Tfloat F32 noattr
  | Double => Tfloat F64 noattr
  | Longdouble => Tfloat F64 noattr
  end.

(** Relation between [typeconv] and integer promotion. *)

Lemma typeconv_integer_promotion:
  forall i, typeconv (proj_type (I i)) = proj_type (I (integer_promotion i)).
Proof.
  destruct i; reflexivity.
Qed.

(** Relation between [classify_binarith] and arithmetic conversion. *)

Lemma classify_binarith_arithmetic_conversion:
  forall t1 t2,
  binarith_type (classify_binarith (proj_type t1) (proj_type t2)) =
  proj_type (usual_arithmetic_conversion t1 t2).
Proof.
  destruct t1; destruct t2; try reflexivity.
- destruct it; destruct it0; reflexivity.
- destruct it; reflexivity.
- destruct it; reflexivity.
- destruct it; reflexivity.
- destruct it; reflexivity.
- destruct it; reflexivity.
- destruct it; reflexivity.
Qed.

End ArithConv.