Correctness of the translation from Clight to C#minor.
Require Import Coqlib.
Require Import Errors.
Require Import Maps.
Require Import Integers.
Require Import Floats.
Require Import AST.
Require Import Values.
Require Import Events.
Require Import Globalenvs.
Require Import Smallstep.
Require Import Ctypes.
Require Import Cop.
Require Import Clight.
Require Import Cminor.
Require Import Csharpminor.
Require Import Cshmgen.
Require Import Values_symbolictype.
Require Import Values_symbolic.
Require Import Normalise.
Require Import NormaliseSpec.
Require Import ExprEval.
Require Import Memory.
Require Import Equivalences.
Require Import MemRel.
Require Import ClightRel.
Properties of operations over types
Remark transl_params_types:
forall params,
map typ_of_type (
map snd params) =
typlist_of_typelist (
type_of_params params).
Proof.
induction params; simpl. auto. destruct a as [id ty]; simpl. f_equal; auto.
Qed.
Lemma transl_fundef_sig1:
forall f tf args res cc,
transl_fundef f =
OK tf ->
classify_fun (
type_of_fundef f) =
fun_case_f args res cc ->
funsig tf =
signature_of_type args res cc.
Proof.
Lemma transl_fundef_sig2:
forall f tf args res cc,
transl_fundef f =
OK tf ->
type_of_fundef f =
Tfunction args res cc ->
funsig tf =
signature_of_type args res cc.
Proof.
Properties of the translation functions
Transformation of expressions and statements.
Lemma transl_expr_lvalue:
forall ge e le m a locofs ta,
Clight.eval_lvalue ge e le m a locofs ->
transl_expr a =
OK ta ->
(
exists tb,
transl_lvalue a =
OK tb /\
make_load tb (
typeof a) =
OK ta).
Proof.
intros until ta;
intros EVAL TR.
inv EVAL;
simpl in TR.
-
(
exists (
Eaddrof id);
auto).
-
(
exists (
Eaddrof id);
auto).
-
monadInv TR.
exists x;
auto.
-
rewrite H0 in TR.
monadInv TR.
econstructor;
split.
simpl.
rewrite H0.
rewrite EQ;
rewrite EQ1;
simpl;
eauto.
auto.
-
rewrite H0 in TR.
monadInv TR.
econstructor;
split.
simpl.
rewrite H0.
rewrite EQ;
simpl;
eauto.
auto.
Qed.
Properties of labeled statements
Lemma transl_lbl_stmt_1:
forall tyret nbrk ncnt n sl tsl,
transl_lbl_stmt tyret nbrk ncnt sl =
OK tsl ->
transl_lbl_stmt tyret nbrk ncnt (
Clight.select_switch n sl) =
OK (
select_switch n tsl).
Proof.
Lemma transl_lbl_stmt_2:
forall tyret nbrk ncnt sl tsl,
transl_lbl_stmt tyret nbrk ncnt sl =
OK tsl ->
transl_statement tyret nbrk ncnt (
seq_of_labeled_statement sl) =
OK (
seq_of_lbl_stmt tsl).
Proof.
induction sl; intros.
monadInv H. auto.
monadInv H. simpl. rewrite EQ; simpl. rewrite (IHsl _ EQ1). simpl. auto.
Qed.
Correctness of Csharpminor construction functions
Section CONSTRUCTORS.
Variable ge:
genv.
Lemma make_intconst_correct:
forall n e le m,
eval_expr ge e le m (
make_intconst n) (
Eval (
Vint n)).
Proof.
Lemma make_floatconst_correct:
forall n e le m,
eval_expr ge e le m (
make_floatconst n) (
Eval (
Vfloat n)).
Proof.
Lemma make_singleconst_correct:
forall n e le m,
eval_expr ge e le m (
make_singleconst n) (
Eval (
Vsingle n)).
Proof.
Lemma make_longconst_correct:
forall n e le m,
eval_expr ge e le m (
make_longconst n) (
Eval (
Vlong n)).
Proof.
Lemma make_singleoffloat_correct:
forall a n e le m,
eval_expr ge e le m a (
Eval (
Vfloat n)) ->
eval_expr ge e le m (
make_singleoffloat a) (
expr_cast_gen Tfloat Signed Tsingle Signed (
Eval (
Vfloat n))).
Proof.
intros. econstructor. eauto. eauto.
Qed.
Lemma make_floatofsingle_correct:
forall a n e le m,
eval_expr ge e le m a (
Eval (
Vsingle n)) ->
eval_expr ge e le m (
make_floatofsingle a) (
expr_cast_gen Tsingle Signed Tfloat Signed (
Eval (
Vsingle n))).
Proof.
intros. econstructor. eauto. auto.
Qed.
Lemma make_floatofint_correct:
forall a n sg e le m,
eval_expr ge e le m a (
Eval (
Vint n)) ->
eval_expr ge e le m (
make_floatofint a sg)
(
expr_cast_gen Tint sg Tfloat Signed (
Eval (
Vint n))).
Proof.
Hint Resolve make_intconst_correct make_floatconst_correct make_longconst_correct
make_singleconst_correct make_singleoffloat_correct make_floatofsingle_correct
make_floatofint_correct:
cshm.
Hint Constructors eval_expr eval_exprlist:
cshm.
Hint Extern 2 (@
eq trace _ _) =>
traceEq:
cshm.
Lemma se_ld:
forall a b,
same_eval a b ->
Val.lessdef a b.
Proof.
red; intros; rewrite H; auto.
Qed.
Lemma make_cmp_ne_zero_correct:
forall ge e le m a v v',
eval_expr ge e le m a v ->
Val.lessdef v'
v ->
exists v'' :
expr_sym,
eval_expr ge e le m (
make_cmp_ne_zero a)
v'' /\
Val.lessdef (
Eunop OpBoolval Tint v')
v''.
Proof.
Lemma make_cast_int_correct:
forall e le m a v v'
sz si,
eval_expr ge e le m a v ->
Val.lessdef v'
v ->
exists v'',
eval_expr ge e le m (
make_cast_int a sz si)
v'' /\
Val.lessdef (
expr_cast_int_int sz si v')
v''.
Proof.
Hint Resolve make_cast_int_correct:
cshm.
Lemma expr_cast_int_int_ld:
forall a b sz sg,
Val.lessdef a b ->
Val.lessdef (
expr_cast_int_int sz sg a)
(
expr_cast_int_int sz sg b).
Proof.
Lemma make_cast_correct:
forall e le m a b v v2 ty1 ty2 v'
(
CAST:
make_cast ty1 ty2 a =
OK b)
(
EVAL:
eval_expr ge e le m a v)
(
SE:
Val.lessdef v2 v)
(
SEM:
sem_cast_expr v2 ty1 ty2 =
Some v'),
exists v'',
eval_expr ge e le m b v'' /\
Val.lessdef v'
v''.
Proof.
intros.
Ltac t :=
eexists;
split; [
eauto;
repeat (
econstructor;
simpl;
eauto)|];
try (
eapply Val.lessdef_trans; [|
eauto]);
try (
(
apply Val.lessdef_unop;
auto) ||
(
apply Val.lessdef_binop;
auto) ||
red;
intros;
simpl;
seval;
auto).
unfold make_cast,
sem_cast_expr in *;
destruct (
classify_cast ty1 ty2)
eqn:?;
inv SEM;
inv CAST;
auto;
try
(
unfold expr_cast_gen;
t;
rewrite Int.sign_ext_above with (
n:=32%
Z);
unfsize;
auto;
Psatz.lia).
-
eapply make_cast_int_correct;
eauto.
-
unfold make_floatofint,
expr_cast_gen.
des si1;
t.
-
unfold make_singleofint,
expr_cast_gen.
des si1;
t.
-
unfold make_intoffloat,
expr_cast_gen.
destruct si2.
edestruct make_cast_int_correct
with (
a:=
Csharpminor.Eunop Ointoffloat a)
as [
v'' [
A B]].
econstructor;
simpl;
eauto.
apply Val.lessdef_unop;
auto.
eexists;
split;
simpl;
eauto.
eapply Val.lessdef_trans; [|
eauto].
apply expr_cast_int_int_ld;
auto.
apply Val.lessdef_unop;
auto.
edestruct make_cast_int_correct
with (
a:=
Csharpminor.Eunop Ointuoffloat a)
as [
v'' [
A B]].
econstructor;
simpl;
eauto.
apply Val.lessdef_unop;
auto.
eexists;
split;
simpl;
eauto.
eapply Val.lessdef_trans; [|
eauto].
apply expr_cast_int_int_ld;
auto.
apply Val.lessdef_unop;
auto.
-
unfold make_intofsingle.
destruct si2.
edestruct make_cast_int_correct
with (
a:=
Csharpminor.Eunop Ointofsingle a)
as [
v'' [
A B]].
econstructor;
simpl;
eauto.
apply Val.lessdef_unop;
auto.
eexists;
split;
simpl;
eauto.
eapply Val.lessdef_trans; [|
eauto].
apply expr_cast_int_int_ld;
auto.
apply Val.lessdef_unop;
auto.
edestruct make_cast_int_correct
with (
a:=
Csharpminor.Eunop Ointuofsingle a)
as [
v'' [
A B]].
econstructor;
simpl;
eauto.
apply Val.lessdef_unop;
auto.
eexists;
split;
simpl;
eauto.
eapply Val.lessdef_trans; [|
eauto].
apply expr_cast_int_int_ld;
auto.
apply Val.lessdef_unop;
auto.
-
unfold make_longofint,
expr_cast_gen.
destruct si1;
eexists; (
split ;[(
econstructor;
simpl;
eauto)|];
auto);
apply Val.lessdef_unop;
auto.
-
eapply make_cast_int_correct.
econstructor;
simpl;
eauto.
apply Val.lessdef_unop;
auto.
-
unfold make_floatoflong,
expr_cast_gen.
simpl.
destruct si1;
eexists; (
split; [
repeat (
econstructor;
simpl;
eauto)|]);
apply Val.lessdef_unop;
auto.
-
unfold make_singleoflong,
expr_cast_gen.
destruct si1;
eexists; (
split; [
repeat (
econstructor;
simpl;
eauto)|]);
apply Val.lessdef_unop;
auto.
-
unfold make_longoffloat,
expr_cast_gen.
destruct si2;
eexists; (
split; [
repeat (
econstructor;
simpl;
eauto)|]);
apply Val.lessdef_unop;
auto.
-
unfold make_longofsingle,
expr_cast_gen.
destruct si2;
eexists; (
split; [
repeat (
econstructor;
simpl;
eauto)|]);
apply Val.lessdef_unop;
auto.
-
unfold make_floatconst,
expr_cast_gen.
eexists; (
split; [
repeat (
econstructor;
simpl;
eauto)|]).
unfold Val.cmpf,
Val.cmpf_bool.
red;
intros;
rewrite eqm_notbool_ceq_cne.
apply Val.lessdef_binop;
auto.
-
unfold make_singleconst.
eexists; (
split; [
repeat (
econstructor;
simpl;
eauto)|]).
red;
intros;
rewrite eqm_notbool_ceq_cne.
apply Val.lessdef_binop;
auto.
-
unfold make_longconst.
simpl.
eexists; (
split; [
repeat (
econstructor;
simpl;
eauto)|]).
red;
intros;
rewrite eqm_notbool_ceq_cne.
apply Val.lessdef_binop;
auto.
-
unfold make_intconst.
simpl.
eexists; (
split; [
repeat (
econstructor;
simpl;
eauto)|]).
red;
intros;
rewrite eqm_notbool_ceq_cne.
apply Val.lessdef_binop;
auto.
-
destruct (
ident_eq id1 id2 &&
fieldlist_eq fld1 fld2);
inv H0.
exists v;
split;
auto.
-
destruct (
ident_eq id1 id2 &&
fieldlist_eq fld1 fld2);
inv H0.
exists v;
split;
auto.
Qed.
Lemma make_boolean_correct:
forall e le m a v v'
ty,
eval_expr ge e le m a v ->
Val.lessdef v'
v ->
exists vb,
eval_expr ge e le m (
make_boolean a ty)
vb
/\
Val.lessdef (
bool_expr v'
ty)
vb.
Proof.
Lemma make_neg_correct:
forall a tya c va va'
v e le m,
Val.lessdef va'
va ->
sem_neg_expr va'
tya =
v ->
make_neg a tya =
OK c ->
eval_expr ge e le m a va ->
exists v',
eval_expr ge e le m c v' /\
Val.lessdef v v'.
Proof.
Lemma make_absfloat_correct:
forall a tya c va va'
v e le m,
Val.lessdef va'
va ->
sem_absfloat_expr va'
tya =
v ->
make_absfloat a tya =
OK c ->
eval_expr ge e le m a va ->
exists v',
eval_expr ge e le m c v' /\
Val.lessdef v v'.
Proof.
Lemma make_notbool_correct:
forall a tya c va va'
v e le m,
Val.lessdef va'
va ->
sem_notbool_expr va'
tya =
v ->
make_notbool a tya =
OK c ->
eval_expr ge e le m a va ->
exists v',
eval_expr ge e le m c v' /\
Val.lessdef v v'.
Proof.
Lemma make_notint_correct:
forall a tya c va va'
v e le m,
Val.lessdef va'
va ->
sem_notint_expr va'
tya =
v ->
make_notint a tya =
OK c ->
eval_expr ge e le m a va ->
exists v',
eval_expr ge e le m c v' /\
Val.lessdef v v'.
Proof.
Definition binary_constructor_correct
(
make:
expr ->
type ->
expr ->
type ->
res expr)
(
sem:
expr_sym ->
type ->
expr_sym ->
type ->
option expr_sym):
Prop :=
forall a tya b tyb c va vb vaa vbb v e le m,
Val.lessdef vaa va ->
Val.lessdef vbb vb ->
sem vaa tya vbb tyb =
Some v ->
make a tya b tyb =
OK c ->
eval_expr ge e le m a va ->
eval_expr ge e le m b vb ->
exists v',
eval_expr ge e le m c v' /\
Val.lessdef v v'.
Section MAKE_BIN.
Variable sem_int:
signedness ->
expr_sym ->
expr_sym ->
option expr_sym.
Variable sem_long:
signedness ->
expr_sym ->
expr_sym ->
option expr_sym.
Variable sem_float:
expr_sym ->
expr_sym ->
option expr_sym.
Variable sem_single:
expr_sym ->
expr_sym ->
option expr_sym.
Variables iop iopu fop sop lop lopu:
binary_operation.
Hypothesis iop_ok:
forall x y m,
eval_binop iop x y m =
sem_int Signed x y.
Hypothesis iopu_ok:
forall x y m,
eval_binop iopu x y m =
sem_int Unsigned x y.
Hypothesis lop_ok:
forall x y m,
eval_binop lop x y m =
sem_long Signed x y.
Hypothesis lopu_ok:
forall x y m,
eval_binop lopu x y m =
sem_long Unsigned x y.
Hypothesis fop_ok:
forall x y m,
eval_binop fop x y m =
sem_float x y.
Hypothesis sop_ok:
forall x y m,
eval_binop sop x y m =
sem_single x y.
Hypothesis si_norm:
forall sg,
preserves_lessdef Val.lessdef (
sem_int sg).
Hypothesis sl_norm:
forall sg,
preserves_lessdef Val.lessdef (
sem_long sg).
Hypothesis sf_norm:
preserves_lessdef Val.lessdef sem_float.
Hypothesis ss_norm:
preserves_lessdef Val.lessdef sem_single.
Lemma make_binarith_correct:
binary_constructor_correct
(
make_binarith iop iopu fop sop lop lopu)
(
sem_binarith_expr sem_int sem_long sem_float sem_single).
Proof.
red;
unfold make_binarith,
sem_binarith_expr;
intros until m;
intros SE1 SE2 SEM MAKE EV1 EV2.
set (
cls :=
classify_binarith tya tyb)
in *.
set (
ty :=
binarith_type cls)
in *.
monadInv MAKE.
destruct (
sem_cast_expr vaa tya ty)
as [
va'|]
eqn:
Ca;
try discriminate.
destruct (
sem_cast_expr vbb tyb ty)
as [
vb'|]
eqn:
Cb;
try discriminate.
exploit make_cast_correct.
eexact EQ.
eauto.
eauto.
eauto.
intros EV1'.
exploit make_cast_correct.
eexact EQ1.
eauto.
eauto.
eauto.
intros EV2'.
destruct EV1'
as [
v'' [
A B]].
destruct EV2'
as [
v''0 [
C D]].
destruct cls;
inv EQ2.
-
generalize (
si_norm s _ _ _ _ B D).
rewrite SEM.
destr_cond_match;
intuition try discriminate.
destruct s;
inv H0;
eexists;
split;
eauto;
repeat (
econstructor;
simpl;
eauto).
rewrite iop_ok;
eauto.
rewrite iopu_ok;
auto.
-
generalize (
sl_norm s _ _ _ _ B D).
rewrite SEM.
destr_cond_match;
intuition try discriminate.
destruct s;
inv H0;
eexists;
split;
eauto;
econstructor;
eauto with cshm.
rewrite lop_ok;
auto.
rewrite lopu_ok;
auto.
-
generalize (
sf_norm _ _ _ _ B D).
rewrite SEM.
destr_cond_match;
intuition try discriminate.
eexists;
split;
eauto;
econstructor;
simpl;
eauto.
erewrite fop_ok;
eauto with cshm.
-
generalize (
ss_norm _ _ _ _ B D).
rewrite SEM.
destr_cond_match;
intuition try discriminate.
eexists;
split;
eauto;
econstructor;
simpl;
eauto.
erewrite sop_ok;
eauto with cshm.
Qed.
Lemma make_binarith_int_correct:
binary_constructor_correct
(
make_binarith_int iop iopu lop lopu)
(
sem_binarith_expr sem_int sem_long (
fun x y =>
None) (
fun x y =>
None)).
Proof.
red;
unfold make_binarith_int,
sem_binarith_expr;
intros until m;
intros SE1 SE2 SEM MAKE EV1 EV2 .
set (
cls :=
classify_binarith tya tyb)
in *.
set (
ty :=
binarith_type cls)
in *.
monadInv MAKE.
destruct (
sem_cast_expr vaa tya ty)
as [
va'|]
eqn:
Ca;
try discriminate.
destruct (
sem_cast_expr vbb tyb ty)
as [
vb'|]
eqn:
Cb;
try discriminate.
exploit make_cast_correct.
eexact EQ.
eauto.
eauto.
eauto.
auto.
intros EV1'.
exploit make_cast_correct.
eexact EQ1.
eauto.
eauto.
eauto.
auto.
intros EV2'.
destruct EV1'
as [
v'' [
A B]].
destruct EV2'
as [
v''0 [
C D]].
destruct cls;
inv EQ2.
-
generalize (
si_norm s _ _ _ _ B D).
rewrite SEM.
destr_cond_match;
intuition try discriminate.
destruct s;
inv H0;
eexists;
split;
eauto;
repeat (
econstructor;
simpl;
eauto).
rewrite iop_ok;
eauto.
rewrite iopu_ok;
auto.
-
generalize (
sl_norm s _ _ _ _ B D).
rewrite SEM.
destr_cond_match;
intuition try discriminate.
destruct s;
inv H0;
eexists;
split;
eauto;
econstructor;
eauto with cshm.
rewrite lop_ok;
auto.
rewrite lopu_ok;
auto.
Qed.
End MAKE_BIN.
Hint Extern 2 (@
eq (
option val)
_ _) => (
simpl;
reflexivity) :
cshm.
Lemma lessdef_mul_commut:
forall a b,
Val.lessdef (
Val.mul a b) (
Val.mul b a).
Proof.
Lemma make_add_correct:
binary_constructor_correct make_add sem_add_expr.
Proof.
Lemma make_sub_correct:
binary_constructor_correct make_sub sem_sub_expr.
Proof.
Lemma make_mul_correct:
binary_constructor_correct make_mul sem_mul_expr.
Proof.
Lemma make_div_correct:
binary_constructor_correct make_div sem_div_expr.
Proof.
Lemma make_mod_correct:
binary_constructor_correct make_mod sem_mod_expr.
Proof.
Lemma make_and_correct:
binary_constructor_correct make_and sem_and_expr.
Proof.
Lemma make_or_correct:
binary_constructor_correct make_or sem_or_expr.
Proof.
Lemma make_xor_correct:
binary_constructor_correct make_xor sem_xor_expr.
Proof.
Ltac comput val :=
let x :=
fresh in set val as x in *;
vm_compute in x;
subst x.
Remark small_shift_amount_1:
forall i,
Int64.ltu i Int64.iwordsize =
true ->
Int.ltu (
Int64.loword i)
Int64.iwordsize' =
true
/\
Int64.unsigned i =
Int.unsigned (
Int64.loword i).
Proof.
Remark small_shift_amount_2:
forall i,
Int64.ltu i (
Int64.repr 32) =
true ->
Int.ltu (
Int64.loword i)
Int.iwordsize =
true.
Proof.
Lemma small_shift_amount_3:
forall i,
Int.ltu i Int64.iwordsize' =
true ->
Int64.unsigned (
Int64.repr (
Int.unsigned i)) =
Int.unsigned i.
Proof.
Lemma make_shl_correct:
binary_constructor_correct make_shl sem_shl_expr.
Proof.
Lemma make_shr_correct:
binary_constructor_correct make_shr sem_shr_expr.
Proof.
Lemma make_cmp_correct:
forall cmp a tya b tyb c va va'
vb'
vb v e le m,
Val.lessdef va'
va ->
Val.lessdef vb'
vb ->
sem_cmp_expr cmp va'
tya vb'
tyb =
Some v ->
make_cmp cmp a tya b tyb =
OK c ->
eval_expr ge e le m a va ->
eval_expr ge e le m b vb ->
exists v',
eval_expr ge e le m c v' /\
Val.lessdef v v'.
Proof.
Lemma transl_unop_correct:
forall op a tya c va va'
v e le m,
transl_unop op a tya =
OK c ->
eval_expr ge e le m a va ->
Val.lessdef va'
va ->
sem_unary_operation_expr op va'
tya =
v ->
exists v',
eval_expr ge e le m c v' /\
Val.lessdef v v'.
Proof.
Lemma transl_binop_correct:
forall op a tya b tyb c va vb va'
vb'
v e le m,
Val.lessdef va'
va ->
Val.lessdef vb'
vb ->
transl_binop op a tya b tyb =
OK c ->
sem_binary_operation_expr op va'
tya vb'
tyb =
Some v ->
eval_expr ge e le m a va ->
eval_expr ge e le m b vb ->
exists v',
eval_expr ge e le m c v' /\
Val.lessdef v v'.
Proof.
Lemma make_load_correct:
forall addr ty code bofs v v'
e le m,
make_load addr ty =
OK code ->
eval_expr ge e le m addr v' ->
Val.lessdef bofs v' ->
deref_loc ty m bofs v ->
exists v'',
eval_expr ge e le m code v'' /\
Val.lessdef v v''.
Proof.
unfold make_load;
intros until m;
intros MKLOAD EVEXP SE DEREF.
inv DEREF.
-
rewrite H in MKLOAD.
inv MKLOAD.
eexists;
split;
eauto;
try reflexivity.
econstructor;
eauto.
revert H0.
unfold Mem.loadv.
generalize (
Mem.lessdef_eqm m _ _ SE).
destr.
inv H0.
auto.
-
rewrite H in MKLOAD.
inv MKLOAD.
eexists;
split;
eauto.
-
rewrite H in MKLOAD.
inv MKLOAD.
eexists;
split;
eauto.
Qed.
Variable needed_stackspace :
ident ->
nat.
Lemma make_memcpy_correct:
forall f dst src ty k e le m m'
v v',
eval_expr ge e le m dst v ->
eval_expr ge e le m src v' ->
assign_loc ty m v v'
m' ->
access_mode ty =
By_copy ->
exists m'',
step ge needed_stackspace (
State f (
make_memcpy dst src ty)
k e le m)
E0 (
State f Sskip k e le m'') /\
mem_equiv m'
m''.
Proof.
Lemma make_store_correct:
forall addr ty rhs code e le m v v'
m'
f k,
make_store addr ty rhs =
OK code ->
eval_expr ge e le m addr v' ->
eval_expr ge e le m rhs v ->
assign_loc ty m v'
v m' ->
exists m'',
step ge needed_stackspace (
State f code k e le m)
E0 (
State f Sskip k e le m'') /\
mem_equiv m'
m''.
Proof.
unfold make_store.
intros until k;
intros MKSTORE EV1 EV2 ASSIGN.
inversion ASSIGN;
subst.
-
rewrite AM in *;
inv MKSTORE.
(
exists m';
split;
eauto);
try reflexivity.
econstructor;
eauto.
-
rewrite AM in *;
inv MKSTORE.
eapply make_memcpy_correct;
eauto.
-
rewrite AM in MKSTORE.
inv MKSTORE.
eapply make_memcpy_correct;
eauto.
Qed.
End CONSTRUCTORS.
Basic preservation invariants
Section CORRECTNESS.
Variable prog:
Clight.program.
Variable tprog:
Csharpminor.program.
Hypothesis TRANSL:
transl_program prog =
OK tprog.
Let ge :=
Genv.globalenv prog.
Let tge :=
Genv.globalenv tprog.
Lemma symbols_preserved:
forall s,
Genv.find_symbol tge s =
Genv.find_symbol ge s.
Proof (
Genv.find_symbol_transf_partial2 transl_fundef transl_globvar _ TRANSL).
Lemma functions_translated:
forall m v f,
Genv.find_funct m ge v =
Some f ->
exists tf,
Genv.find_funct m tge v =
Some tf /\
transl_fundef f =
OK tf.
Proof (
Genv.find_funct_transf_partial2 transl_fundef transl_globvar _ TRANSL).
Lemma function_ptr_translated:
forall b f,
Genv.find_funct_ptr ge b =
Some f ->
exists tf,
Genv.find_funct_ptr tge b =
Some tf /\
transl_fundef f =
OK tf.
Proof (
Genv.find_funct_ptr_transf_partial2 transl_fundef transl_globvar _ TRANSL).
Lemma var_info_translated:
forall b v,
Genv.find_var_info ge b =
Some v ->
exists tv,
Genv.find_var_info tge b =
Some tv /\
transf_globvar transl_globvar v =
OK tv.
Proof (
Genv.find_var_info_transf_partial2 transl_fundef transl_globvar _ TRANSL).
Lemma var_info_rev_translated:
forall b tv,
Genv.find_var_info tge b =
Some tv ->
exists v,
Genv.find_var_info ge b =
Some v /\
transf_globvar transl_globvar v =
OK tv.
Proof (
Genv.find_var_info_rev_transf_partial2 transl_fundef transl_globvar _ TRANSL).
Lemma block_is_volatile_preserved:
forall b,
block_is_volatile tge b =
block_is_volatile ge b.
Proof.
Matching between environments
In this section, we define a matching relation between
a Clight local environment and a Csharpminor local environment.
Record match_env (
e:
Clight.env) (
te:
Csharpminor.env) :
Prop :=
mk_match_env {
me_local:
forall id b ty,
e!
id =
Some (
b,
ty) ->
te!
id =
Some(
b,
sizeof ty);
me_local_inv:
forall id b sz,
te!
id =
Some (
b,
sz) ->
exists ty,
e!
id =
Some(
b,
ty)
}.
Lemma match_env_globals:
forall e te id,
match_env e te ->
e!
id =
None ->
te!
id =
None.
Proof.
intros.
destruct (
te!
id)
as [[
b sz] | ]
eqn:?;
auto.
exploit me_local_inv;
eauto.
intros [
ty EQ].
congruence.
Qed.
Lemma match_env_same_blocks:
forall e te,
match_env e te ->
blocks_of_env te =
Clight.blocks_of_env e.
Proof.
Lemma match_env_free_blocks:
forall e te m m',
match_env e te ->
Mem.free_list m (
Clight.blocks_of_env e) =
Some m' ->
Mem.free_list m (
blocks_of_env te) =
Some m'.
Proof.
Lemma match_env_empty:
match_env Clight.empty_env Csharpminor.empty_env.
Proof.
The following lemmas establish the match_env invariant at
the beginning of a function invocation, after allocation of
local variables and initialization of the parameters.
Lemma match_env_alloc_variables:
forall e1 m1 vars e2 m2,
Clight.alloc_variables e1 m1 vars e2 m2 ->
forall te1,
match_env e1 te1 ->
exists te2,
Csharpminor.alloc_variables te1 m1 (
map transl_var vars)
te2 m2
/\
match_env e2 te2.
Proof.
induction 1;
intros;
simpl.
exists te1;
split.
constructor.
auto.
exploit (
IHalloc_variables (
PTree.set id (
b1,
sizeof ty)
te1)).
constructor.
intros until ty0.
repeat rewrite PTree.gsspec.
destruct (
peq id0 id);
intros.
congruence.
eapply me_local;
eauto.
intros until sz.
repeat rewrite PTree.gsspec.
destruct (
peq id0 id);
intros.
exists ty;
congruence.
eapply me_local_inv;
eauto.
intros [
te2 [
ALLOC MENV]].
exists te2;
split.
econstructor;
eauto.
rewrite Zmax_r;
simpl;
eauto.
generalize (
sizeof_pos ty);
omega.
rewrite Zmax_r;
simpl;
eauto.
generalize (
sizeof_pos ty);
omega.
auto.
Qed.
Lemma create_undef_temps_match:
forall temps,
create_undef_temps (
map fst temps) =
Clight.create_undef_temps temps.
Proof.
induction temps; simpl. auto.
destruct a as [id ty]. simpl. decEq. auto.
Qed.
Lemma bind_parameter_temps_match:
forall vars vals le1 le2,
Clight.bind_parameter_temps vars vals le1 =
Some le2 ->
bind_parameters (
map fst vars)
vals le1 =
Some le2.
Proof.
induction vars; simpl; intros.
destruct vals; inv H. auto.
destruct a as [id ty]. destruct vals; try discriminate. auto.
Qed.
Proof of semantic preservation
Semantic preservation for expressions
The proof of semantic preservation for the translation of expressions
relies on simulation diagrams of the following form:
e, le, m, a ------------------- te, le, m, ta
| |
| |
| |
v v
e, le, m, v ------------------- te, le, m, v
Left: evaluation of r-value expression
a in Clight.
Right: evaluation of its translation
ta in Csharpminor.
Top (precondition): matching between environments
e,
te,
plus well-typedness of expression
a.
Bottom (postcondition): the result values
v
are identical in both evaluations.
We state these diagrams as the following properties, parameterized
by the Clight evaluation.
Section EXPR.
Variable e:
Clight.env.
Variable le:
temp_env.
Variable m:
mem.
Variable te:
Csharpminor.env.
Hypothesis MENV:
match_env e te.
Lemma transl_expr_lvalue_correct:
(
forall a v,
Clight.eval_expr ge e le m a v ->
forall ta (
TR:
transl_expr a =
OK ta) ,
exists v',
Csharpminor.eval_expr tge te le m ta v' /\
Val.lessdef v v')
/\(
forall a v,
Clight.eval_lvalue ge e le m a v ->
forall ta (
TR:
transl_lvalue a =
OK ta),
exists v',
Csharpminor.eval_expr tge te le m ta v' /\
Val.lessdef v v') .
Proof.
Lemma transl_expr_correct:
forall a v,
Clight.eval_expr ge e le m a v ->
forall ta,
transl_expr a =
OK ta ->
exists v',
Csharpminor.eval_expr tge te le m ta v' /\
Val.lessdef v v'.
Proof.
Lemma transl_lvalue_correct:
forall a v,
Clight.eval_lvalue ge e le m a v ->
forall ta,
transl_lvalue a =
OK ta ->
exists v',
Csharpminor.eval_expr tge te le m ta v' /\
Val.lessdef v v'.
Proof.
Lemma transl_arglist_correct:
forall al tyl vl,
Clight.eval_exprlist ge e le m al tyl vl ->
forall tal,
transl_arglist al tyl =
OK tal ->
exists vl',
list_forall2 Val.lessdef vl vl' /\
Csharpminor.eval_exprlist tge te le m tal vl'.
Proof.
induction 1;
intros tal TAL.
-
monadInv TAL.
exists nil;
split;
constructor.
-
monadInv TAL.
destruct (
IHeval_exprlist _ EQ0)
as [
vl' [
A B]].
destruct (
transl_expr_correct _ _ H _ EQ)
as [
v' [
C D]].
destruct (
make_cast_correct _ _ _ _ _ _ _ _ _ _ _ EQ1 C D H0)
as [
v0 [
E F]].
(
exists (
v0::
vl');
split;
auto).
constructor;
auto.
constructor;
auto.
Qed.
Lemma typlist_of_arglist_eq:
forall m'
al tyl vl,
Clight.eval_exprlist ge e le m'
al tyl vl ->
typlist_of_arglist al tyl =
typlist_of_typelist tyl.
Proof.
clear.
induction 1; simpl.
auto.
f_equal; auto.
Qed.
End EXPR.
Semantic preservation for statements
The simulation diagram for the translation of statements and functions
is a "plus" diagram of the form
I
S1 ------- R1
| |
t | + | t
v v
S2 ------- R2
I I
The invariant
I is the
match_states predicate that we now define.
Inductive match_transl:
stmt ->
cont ->
stmt ->
cont ->
Prop :=
|
match_transl_0:
forall ts tk,
match_transl ts tk ts tk
|
match_transl_1:
forall ts tk,
match_transl (
Sblock ts)
tk ts (
Kblock tk).
Variable needed_stackspace :
ident ->
nat .
Lemma match_transl_step:
forall ts tk ts'
tk'
f te le m,
match_transl (
Sblock ts)
tk ts'
tk' ->
star (
fun ge =>
step ge needed_stackspace )
tge (
State f ts'
tk'
te le m)
E0 (
State f ts (
Kblock tk)
te le m).
Proof.
Inductive match_cont:
type ->
nat ->
nat ->
Clight.cont ->
Csharpminor.cont ->
Prop :=
|
match_Kstop:
forall tyret nbrk ncnt,
match_cont tyret nbrk ncnt Clight.Kstop Kstop
|
match_Kseq:
forall tyret nbrk ncnt s k ts tk,
transl_statement tyret nbrk ncnt s =
OK ts ->
match_cont tyret nbrk ncnt k tk ->
match_cont tyret nbrk ncnt
(
Clight.Kseq s k)
(
Kseq ts tk)
|
match_Kloop1:
forall tyret s1 s2 k ts1 ts2 nbrk ncnt tk,
transl_statement tyret 1%
nat 0%
nat s1 =
OK ts1 ->
transl_statement tyret 0%
nat (
S ncnt)
s2 =
OK ts2 ->
match_cont tyret nbrk ncnt k tk ->
match_cont tyret 1%
nat 0%
nat
(
Clight.Kloop1 s1 s2 k)
(
Kblock (
Kseq ts2 (
Kseq (
Sloop (
Sseq (
Sblock ts1)
ts2)) (
Kblock tk))))
|
match_Kloop2:
forall tyret s1 s2 k ts1 ts2 nbrk ncnt tk,
transl_statement tyret 1%
nat 0%
nat s1 =
OK ts1 ->
transl_statement tyret 0%
nat (
S ncnt)
s2 =
OK ts2 ->
match_cont tyret nbrk ncnt k tk ->
match_cont tyret 0%
nat (
S ncnt)
(
Clight.Kloop2 s1 s2 k)
(
Kseq (
Sloop (
Sseq (
Sblock ts1)
ts2)) (
Kblock tk))
|
match_Kswitch:
forall tyret nbrk ncnt k tk,
match_cont tyret nbrk ncnt k tk ->
match_cont tyret 0%
nat (
S ncnt)
(
Clight.Kswitch k)
(
Kblock tk)
|
match_Kcall_some:
forall tyret nbrk ncnt nbrk'
ncnt'
f e k id tf te le le'
tk,
transl_function f =
OK tf ->
match_env e te ->
temp_env_equiv Val.lessdef le le' ->
match_cont (
Clight.fn_return f)
nbrk'
ncnt'
k tk ->
match_cont tyret nbrk ncnt
(
Clight.Kcall id f e le k)
(
Kcall id tf te le'
tk).
Inductive match_states:
Clight.state ->
Csharpminor.state ->
Prop :=
|
match_state:
forall f nbrk ncnt s k e le le'
m m'
tf ts tk te ts'
tk'
(
TRF:
transl_function f =
OK tf)
(
TR:
transl_statement (
Clight.fn_return f)
nbrk ncnt s =
OK ts)
(
MTR:
match_transl ts tk ts'
tk')
(
MENV:
match_env e te)
(
MK:
match_cont (
Clight.fn_return f)
nbrk ncnt k tk)
(
TE:
temp_env_equiv Val.lessdef le le')
(
ME:
mem_lessdef m m'),
match_states (
Clight.State f s k e le m)
(
State tf ts'
tk'
te le'
m')
|
match_callstate:
forall fd args args'
k m m'
tfd tk targs tres cconv
(
TR:
transl_fundef fd =
OK tfd)
(
MK:
match_cont Tvoid 0%
nat 0%
nat k tk)
(
ISCC:
Clight.is_call_cont k)
(
TY:
type_of_fundef fd =
Tfunction targs tres cconv)
(
ME:
mem_lessdef m m')
(
ARGS_eq:
list_forall2 (
Val.lessdef)
args args'),
match_states (
Clight.Callstate fd args k m)
(
Callstate tfd args'
tk m')
|
match_returnstate:
forall res res'
k m m'
tk
(
MK:
match_cont Tvoid 0%
nat 0%
nat k tk)
(
MRES:
Val.lessdef res res')
(
ME:
mem_lessdef m m'),
match_states (
Clight.Returnstate res k m)
(
Returnstate res'
tk m').
Remark match_states_skip:
forall f e le le'
te nbrk ncnt k tf tk m m',
transl_function f =
OK tf ->
match_env e te ->
match_cont (
Clight.fn_return f)
nbrk ncnt k tk ->
mem_lessdef m m' ->
temp_env_equiv Val.lessdef le le' ->
match_states (
Clight.State f ClightSyntax.Sskip k e le m) (
State tf Sskip tk te le'
m').
Proof.
intros. econstructor; eauto. simpl; reflexivity. constructor.
Qed.
Commutation between label resolution and compilation
Section FIND_LABEL.
Variable lbl:
label.
Variable tyret:
type.
Lemma transl_find_label:
forall s nbrk ncnt k ts tk
(
TR:
transl_statement tyret nbrk ncnt s =
OK ts)
(
MC:
match_cont tyret nbrk ncnt k tk),
match Clight.find_label lbl s k with
|
None =>
find_label lbl ts tk =
None
|
Some (
s',
k') =>
exists ts',
exists tk',
exists nbrk',
exists ncnt',
find_label lbl ts tk =
Some (
ts',
tk')
/\
transl_statement tyret nbrk'
ncnt'
s' =
OK ts'
/\
match_cont tyret nbrk'
ncnt'
k'
tk'
end
with transl_find_label_ls:
forall ls nbrk ncnt k tls tk
(
TR:
transl_lbl_stmt tyret nbrk ncnt ls =
OK tls)
(
MC:
match_cont tyret nbrk ncnt k tk),
match Clight.find_label_ls lbl ls k with
|
None =>
find_label_ls lbl tls tk =
None
|
Some (
s',
k') =>
exists ts',
exists tk',
exists nbrk',
exists ncnt',
find_label_ls lbl tls tk =
Some (
ts',
tk')
/\
transl_statement tyret nbrk'
ncnt'
s' =
OK ts'
/\
match_cont tyret nbrk'
ncnt'
k'
tk'
end.
Proof.
intro s;
case s;
intros;
try (
monadInv TR);
simpl.
-
auto.
-
unfold make_store,
make_memcpy in EQ3.
destruct (
access_mode (
typeof e));
inv EQ3;
auto.
-
auto.
-
simpl in TR.
destruct (
classify_fun (
typeof e));
monadInv TR.
auto.
-
auto.
-
exploit (
transl_find_label s0 nbrk ncnt (
Clight.Kseq s1 k));
eauto.
econstructor;
eauto.
destruct (
Clight.find_label lbl s0 (
Clight.Kseq s1 k))
as [[
s'
k'] | ].
intros [
ts' [
tk' [
nbrk' [
ncnt' [
A [
B C]]]]]].
rewrite A.
exists ts';
exists tk';
exists nbrk';
exists ncnt';
auto.
intro.
rewrite H.
eapply transl_find_label;
eauto.
-
exploit (
transl_find_label s0);
eauto.
destruct (
Clight.find_label lbl s0 k)
as [[
s'
k'] | ].
intros [
ts' [
tk' [
nbrk' [
ncnt' [
A [
B C]]]]]].
rewrite A.
exists ts';
exists tk';
exists nbrk';
exists ncnt';
auto.
intro.
rewrite H.
eapply transl_find_label;
eauto.
-
exploit (
transl_find_label s0 1%
nat 0%
nat (
Kloop1 s0 s1 k));
eauto.
econstructor;
eauto.
destruct (
Clight.find_label lbl s0 (
Kloop1 s0 s1 k))
as [[
s'
k'] | ].
intros [
ts' [
tk' [
nbrk' [
ncnt' [
A [
B C]]]]]].
rewrite A.
exists ts';
exists tk';
exists nbrk';
exists ncnt';
auto.
intro.
rewrite H.
eapply transl_find_label;
eauto.
econstructor;
eauto.
-
auto.
-
auto.
-
simpl in TR.
destruct o;
monadInv TR.
auto.
auto.
-
assert (
exists b,
ts =
Sblock (
Sswitch b x x0)).
{
destruct (
classify_switch (
typeof e));
inv EQ2;
econstructor;
eauto. }
destruct H as [
b EQ3];
rewrite EQ3;
simpl.
eapply transl_find_label_ls with (
k :=
Clight.Kswitch k);
eauto.
econstructor;
eauto.
-
destruct (
ident_eq lbl l).
exists x;
exists tk;
exists nbrk;
exists ncnt;
auto.
eapply transl_find_label;
eauto.
-
auto.
-
intro ls;
case ls;
intros;
monadInv TR;
simpl.
auto.
exploit (
transl_find_label s nbrk ncnt (
Clight.Kseq (
seq_of_labeled_statement l)
k));
eauto.
econstructor;
eauto.
apply transl_lbl_stmt_2;
eauto.
destruct (
Clight.find_label lbl s (
Clight.Kseq (
seq_of_labeled_statement l)
k))
as [[
s'
k'] | ].
intros [
ts' [
tk' [
nbrk' [
ncnt' [
A [
B C]]]]]].
rewrite A.
exists ts';
exists tk';
exists nbrk';
exists ncnt';
auto.
intro.
rewrite H.
eapply transl_find_label_ls;
eauto.
Qed.
End FIND_LABEL.
Properties of call continuations
Lemma match_cont_call_cont:
forall tyret'
nbrk'
ncnt'
tyret nbrk ncnt k tk,
match_cont tyret nbrk ncnt k tk ->
match_cont tyret'
nbrk'
ncnt' (
Clight.call_cont k) (
call_cont tk).
Proof.
induction 1; simpl; intros; auto.
constructor.
econstructor; eauto.
Qed.
Lemma match_cont_is_call_cont:
forall tyret nbrk ncnt k tk tyret'
nbrk'
ncnt',
match_cont tyret nbrk ncnt k tk ->
Clight.is_call_cont k ->
match_cont tyret'
nbrk'
ncnt'
k tk /\
is_call_cont tk.
Proof.
intros. inv H; simpl in H0; try contradiction; simpl.
split; auto; constructor.
split; auto; econstructor; eauto.
Qed.
The simulation proof
Lemma match_states_mem_equiv:
forall f s ts k e e'
te tf tk m1 m2 m2',
mem_lessdef m2 m2' ->
match_states (
Clight.State f s k e te m1)
(
State tf ts tk e'
te m2) ->
match_states (
Clight.State f s k e te m1)
(
State tf ts tk e'
te m2').
Proof.
intros f s ts k e e' te tf tk m1 m2 m2' ME MS.
inv MS.
econstructor; eauto.
rewrite ME0; auto.
Qed.
Lemma eval_unop_same_eval:
forall op v1 v sv',
eval_unop op v1 =
Some v ->
Val.lessdef v1 sv' ->
exists sv,
eval_unop op sv' =
Some sv /\
Val.lessdef v sv.
Proof.
intros op v1 v sv'
EU SE.
destruct op;
simpl in *;
inv EU;
(
eexists;
split;
eauto);
try (
apply Val.lessdef_unop;
auto).
Qed.
Lemma eval_binop_same_eval:
forall op v1 v2 v sv'
sv2'
m m',
eval_binop op v1 v2 m =
Some v ->
Val.lessdef v1 sv' ->
Val.lessdef v2 sv2' ->
exists sv,
eval_binop op sv'
sv2'
m' =
Some sv /\
Val.lessdef v sv.
Proof.
intros op v1 v2 v sv'
sv2'
m m'
EB SE SE2.
destruct op;
simpl in *;
inv EB;
(
eexists;
split;
eauto);
try (
apply Val.lessdef_binop;
auto).
Qed.
Lemma mem_equiv_eval_expr:
forall ge e te m m'
a sv,
mem_lessdef m m' ->
eval_expr ge e te m a sv ->
exists sv',
eval_expr ge e te m'
a sv' /\
Val.lessdef sv sv'.
Proof.
intros ge0 e te m m'
a sv ME EV.
induction EV.
-
eexists;
split;
eauto.
econstructor;
eauto.
-
eexists;
split;
eauto.
econstructor;
eauto.
-
eexists;
split;
eauto.
econstructor;
eauto.
-
destruct IHEV as [
sv' [
A B]].
destruct (
eval_unop_same_eval _ _ _ _ H B)
as [
sv [
C D]].
eexists;
split.
econstructor;
simpl;
eauto.
auto.
-
destruct IHEV1 as [
sv' [
A B]].
destruct IHEV2 as [
sv'' [
A'
B']].
destruct (
eval_binop_same_eval _ _ _ _ _ _ _ m'
H B B')
as [
sv [
C D]].
eexists;
split.
econstructor;
simpl;
eauto.
auto.
-
destruct IHEV as [
sv' [
A B]].
unfold Mem.loadv in H.
revert H;
destr_cond_match;
intros;
try discriminate.
destruct (
mem_rel_load _ wf_mr_ld chunk m m'
_ _ _ ME H)
as [
v' [
C D]].
eexists;
split.
econstructor;
simpl;
eauto.
unfold Mem.loadv in *.
setoid_rewrite <-
mem_rel_norm with (
m':=
m');
eauto.
generalize (
Mem.lessdef_eqm m _ _ B).
rewrite Heqv0.
intro E;
inv E;
eauto.
auto.
Qed.
Lemma free_same_eval_cmp:
forall ge e le m a v v',
eval_expr ge e le m a v ->
Val.lessdef v'
v ->
exists v'' :
expr_sym,
eval_expr ge e le m (
make_cmp_ne_zero a)
v'' /\
Val.lessdef (
Eunop OpBoolval Tint v')
v''.
Proof.
intros.
inv H;
try (
eexists;
split; [
repeat (
econstructor;
simpl;
eauto)|]; [
idtac]);
try (
red;
intros;
rewrite nec_cmp_ne_zero;
apply Val.lessdef_binop;
auto).
des op;
try (
eexists;
split; [
repeat (
econstructor;
simpl;
eauto)|]; [
idtac]);
try (
red;
intros;
rewrite nec_cmp_ne_zero;
apply Val.lessdef_binop;
auto);
inv H3;
red;
intros;
unfold Val.cmp,
Val.cmpu,
Val.cmp_bool,
Val.cmpu_bool,
Val.cmpf,
Val.cmpfs,
Val.cmpl,
Val.cmplu,
Val.cmpf_bool,
Val.cmpfs_bool,
Val.cmpl_bool,
Val.cmplu_bool;
try rewrite norm_boolval_cmp;
apply Val.lessdef_unop;
auto.
Qed.
Lemma alloc_variables_mem_equiv:
forall m e1 vars e2 m2,
alloc_variables e1 m vars e2 m2 ->
forall m',
mem_lessdef m m' ->
exists m2',
alloc_variables e1 m'
vars e2 m2' /\
mem_lessdef m2 m2'.
Proof.
induction 1;
simpl;
intros.
eexists;
split;
eauto.
econstructor.
eapply alloc_mem_rel in H;
eauto.
destruct H as [
m2' [
A B]].
apply IHalloc_variables in B.
destruct B as [
m2'0 [
B C]].
eexists;
split;
eauto.
econstructor;
eauto.
apply wf_mr_ld.
Qed.
Require Import VarSort.
Lemma var_sort_eq:
forall l,
varsort' (
map transl_var l) =
map transl_var (
varsort l).
Proof.
induction l.
auto.
simpl.
rewrite IHl.
generalize (
varsort l).
clear.
induction l;
simpl;
auto.
unfold le2,
le1 in *.
simpl.
repeat destr.
Qed.
Instance lessdef_preorder:
RelationClasses.PreOrder Val.lessdef.
Proof.
Lemma mem_eq_ld:
forall m1 m2,
mem_equiv m1 m2 ->
mem_lessdef m1 m2.
Proof.
intros m1 m2 ME;
inv ME;
constructor;
eauto.
red;
intros.
generalize (
mem_contents_eq b ofs).
destr.
apply se_ld;
auto.
apply H2.
red in H2.
destr.
Qed.
Hint Resolve wf_mr_ld wf_mr_norm_ld.
Lemma transl_step:
forall S1 t S2,
Clight.step2 ge needed_stackspace S1 t S2 ->
forall T1,
match_states S1 T1 ->
exists T2,
plus (
fun ge =>
step ge needed_stackspace)
tge T1 t T2 /\
match_states S2 T2.
Proof.
Lemma transl_initial_states:
forall sg S,
Clight.initial_state prog sg S ->
exists R,
initial_state tprog sg R /\
match_states S R.
Proof.
Lemma transl_final_states:
forall S R r,
match_states S R ->
Clight.final_state S r ->
final_state R r.
Proof.
Theorem transl_program_correct:
forall sg,
forward_simulation
(
Clight.semantics2 prog needed_stackspace sg)
(
Csharpminor.semantics tprog needed_stackspace sg).
Proof.
End CORRECTNESS.