(* *********************************************************************)
(*                                                                     *)
(*              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 INRIA Non-Commercial License Agreement.     *)
(*                                                                     *)
(* *********************************************************************)

(** Recognition of combined operations, addressing modes and conditions 
  during the [CSE] phase. *)

Require Import Coqlib.
Require Import Integers.
Require Import Values.
Require Import Memory.
Require Import Op.
Require Import RTL.
Require Import CSEdomain.
Require Import CombineOp.

Section COMBINE.

Variable ge: genv.
Variable sp: val.
Variable m: mem.
Variable get: valnum -> option rhs.
Variable valu: valnum -> val.
Hypothesis get_sound: forall v rhs, get v = Some rhs -> rhs_eval_to valu ge sp m rhs (valu v).

Lemma get_op_sound:
  forall v op vl, get v = Some (Op op vl) -> eval_operation ge sp op (map valu vl) m = Some (valu v).
Proof.
  intros. exploit get_sound; eauto. intros REV; inv REV; auto. 
Qed.

Ltac UseGetSound :=
  match goal with
  | [ H: get _ = Some _ |- _ ] =>
      let x := fresh "EQ" in (generalize (get_op_sound _ _ _ H); intros x; simpl in x; FuncInv)
  end.
  
Lemma combine_compimm_ne_0_sound:
  forall x cond args,
  combine_compimm_ne_0 get x = Some(cond, args) ->
  eval_condition cond (map valu args) m = Val.cmp_bool Cne (valu x) (Vint Int.zero) /\
  eval_condition cond (map valu args) m = Val.cmpu_bool (Mem.valid_pointer m) Cne (valu x) (Vint Int.zero).
Proof.
  intros until args. functional induction (combine_compimm_ne_0 get x); intros EQ; inv EQ.
  (* of cmp *)
  UseGetSound. rewrite <- H. 
  destruct (eval_condition cond (map valu args) m); simpl; auto. destruct b; auto.
  (* of and *)
  UseGetSound. rewrite <- H. 
  destruct v; simpl; auto. 
Qed.

Lemma combine_compimm_eq_0_sound:
  forall x cond args,
  combine_compimm_eq_0 get x = Some(cond, args) ->
  eval_condition cond (map valu args) m = Val.cmp_bool Ceq (valu x) (Vint Int.zero) /\
  eval_condition cond (map valu args) m = Val.cmpu_bool (Mem.valid_pointer m) Ceq (valu x) (Vint Int.zero).
Proof.
  intros until args. functional induction (combine_compimm_eq_0 get x); intros EQ; inv EQ.
  (* of cmp *)
  UseGetSound. rewrite <- H.
  rewrite eval_negate_condition. 
  destruct (eval_condition c (map valu args) m); simpl; auto. destruct b; auto.
  (* of and *)
  UseGetSound. rewrite <- H. destruct v; auto. 
Qed.

Lemma combine_compimm_eq_1_sound:
  forall x cond args,
  combine_compimm_eq_1 get x = Some(cond, args) ->
  eval_condition cond (map valu args) m = Val.cmp_bool Ceq (valu x) (Vint Int.one) /\
  eval_condition cond (map valu args) m = Val.cmpu_bool (Mem.valid_pointer m) Ceq (valu x) (Vint Int.one).
Proof.
  intros until args. functional induction (combine_compimm_eq_1 get x); intros EQ; inv EQ.
  (* of cmp *)
  UseGetSound. rewrite <- H. 
  destruct (eval_condition cond (map valu args) m); simpl; auto. destruct b; auto.
Qed.

Lemma combine_compimm_ne_1_sound:
  forall x cond args,
  combine_compimm_ne_1 get x = Some(cond, args) ->
  eval_condition cond (map valu args) m = Val.cmp_bool Cne (valu x) (Vint Int.one) /\
  eval_condition cond (map valu args) m = Val.cmpu_bool (Mem.valid_pointer m) Cne (valu x) (Vint Int.one).
Proof.
  intros until args. functional induction (combine_compimm_ne_1 get x); intros EQ; inv EQ.
  (* of cmp *)
  UseGetSound. rewrite <- H. 
  rewrite eval_negate_condition.
  destruct (eval_condition c (map valu args) m); simpl; auto. destruct b; auto.
Qed.

Theorem combine_cond_sound:
  forall cond args cond' args',
  combine_cond get cond args = Some(cond', args') ->
  eval_condition cond' (map valu args') m = eval_condition cond (map valu args) m.
Proof.
  intros. functional inversion H; subst.
  (* compimm ne zero *)
  simpl; eapply combine_compimm_ne_0_sound; eauto.
  (* compimm ne one *)
  simpl; eapply combine_compimm_ne_1_sound; eauto.
  (* compimm eq zero *)
  simpl; eapply combine_compimm_eq_0_sound; eauto.
  (* compimm eq one *)
  simpl; eapply combine_compimm_eq_1_sound; eauto.
  (* compuimm ne zero *)
  simpl; eapply combine_compimm_ne_0_sound; eauto.
  (* compuimm ne one *)
  simpl; eapply combine_compimm_ne_1_sound; eauto.
  (* compuimm eq zero *)
  simpl; eapply combine_compimm_eq_0_sound; eauto.
  (* compuimm eq one *)
  simpl; eapply combine_compimm_eq_1_sound; eauto.
Qed.

Theorem combine_addr_sound:
  forall addr args addr' args',
  combine_addr get addr args = Some(addr', args') ->
  eval_addressing ge sp addr' (map valu args') = eval_addressing ge sp addr (map valu args).
Proof.
  intros. functional inversion H; subst.
  (* indexed - lea *)
  UseGetSound. simpl. eapply eval_offset_addressing_total; eauto. 
Qed.

Theorem combine_op_sound:
  forall op args op' args',
  combine_op get op args = Some(op', args') ->
  eval_operation ge sp op' (map valu args') m = eval_operation ge sp op (map valu args) m.
Proof.
  intros. functional inversion H; subst.
(* lea-lea *)
  simpl. eapply combine_addr_sound; eauto. 
(* andimm - andimm *)
  UseGetSound; simpl. rewrite <- H0. rewrite Val.and_assoc. auto.
(* orimm - orimm *)
  UseGetSound; simpl. rewrite <- H0. rewrite Val.or_assoc. auto.
(* xorimm - xorimm *)
  UseGetSound; simpl. rewrite <- H0. rewrite Val.xor_assoc. auto.
(* cmp *)
  simpl. decEq; decEq. eapply combine_cond_sound; eauto.
Qed.

End COMBINE.