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Diffstat (limited to 'backends/coq/Primitives.v')
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diff --git a/backends/coq/Primitives.v b/backends/coq/Primitives.v new file mode 100644 index 00000000..c27b8aed --- /dev/null +++ b/backends/coq/Primitives.v @@ -0,0 +1,478 @@ +Require Import Lia. +Require Coq.Strings.Ascii. +Require Coq.Strings.String. +Require Import Coq.Program.Equality. +Require Import Coq.ZArith.ZArith. +Require Import Coq.ZArith.Znat. +Require Import List. +Import ListNotations. + +Module Primitives. + + (* TODO: use more *) +Declare Scope Primitives_scope. + +(*** Result *) + +Inductive result A := + | Return : A -> result A + | Fail_ : result A. + +Arguments Return {_} a. +Arguments Fail_ {_}. + +Definition bind {A B} (m: result A) (f: A -> result B) : result B := + match m with + | Fail_ => Fail_ + | Return x => f x + end. + +Definition return_ {A: Type} (x: A) : result A := Return x . +Definition fail_ {A: Type} : result A := Fail_ . + +Notation "x <- c1 ; c2" := (bind c1 (fun x => c2)) + (at level 61, c1 at next level, right associativity). + +(** Monadic assert *) +Definition massert (b: bool) : result unit := + if b then Return tt else Fail_. + +(** Normalize and unwrap a successful result (used for globals) *) +Definition eval_result_refl {A} {x} (a: result A) (p: a = Return x) : A := + match a as r return (r = Return x -> A) with + | Return a' => fun _ => a' + | Fail_ => fun p' => + False_rect _ (eq_ind Fail_ + (fun e : result A => + match e with + | Return _ => False + | Fail_ => True + end) + I (Return x) p') + end p. + +Notation "x %global" := (eval_result_refl x eq_refl) (at level 40). +Notation "x %return" := (eval_result_refl x eq_refl) (at level 40). + +(* Sanity check *) +Check (if true then Return (1 + 2) else Fail_)%global = 3. + +(*** Misc *) + + +Definition string := Coq.Strings.String.string. +Definition char := Coq.Strings.Ascii.ascii. +Definition char_of_byte := Coq.Strings.Ascii.ascii_of_byte. + +Definition mem_replace_fwd (a : Type) (x : a) (y : a) : a := x . +Definition mem_replace_back (a : Type) (x : a) (y : a) : a := y . + +(*** Scalars *) + +Definition i8_min : Z := -128%Z. +Definition i8_max : Z := 127%Z. +Definition i16_min : Z := -32768%Z. +Definition i16_max : Z := 32767%Z. +Definition i32_min : Z := -2147483648%Z. +Definition i32_max : Z := 2147483647%Z. +Definition i64_min : Z := -9223372036854775808%Z. +Definition i64_max : Z := 9223372036854775807%Z. +Definition i128_min : Z := -170141183460469231731687303715884105728%Z. +Definition i128_max : Z := 170141183460469231731687303715884105727%Z. +Definition u8_min : Z := 0%Z. +Definition u8_max : Z := 255%Z. +Definition u16_min : Z := 0%Z. +Definition u16_max : Z := 65535%Z. +Definition u32_min : Z := 0%Z. +Definition u32_max : Z := 4294967295%Z. +Definition u64_min : Z := 0%Z. +Definition u64_max : Z := 18446744073709551615%Z. +Definition u128_min : Z := 0%Z. +Definition u128_max : Z := 340282366920938463463374607431768211455%Z. + +(** The bounds of [isize] and [usize] vary with the architecture. *) +Axiom isize_min : Z. +Axiom isize_max : Z. +Definition usize_min : Z := 0%Z. +Axiom usize_max : Z. + +Open Scope Z_scope. + +(** We provide those lemmas to reason about the bounds of [isize] and [usize] *) +Axiom isize_min_bound : isize_min <= i32_min. +Axiom isize_max_bound : i32_max <= isize_max. +Axiom usize_max_bound : u32_max <= usize_max. + +Inductive scalar_ty := + | Isize + | I8 + | I16 + | I32 + | I64 + | I128 + | Usize + | U8 + | U16 + | U32 + | U64 + | U128 +. + +Definition scalar_min (ty: scalar_ty) : Z := + match ty with + | Isize => isize_min + | I8 => i8_min + | I16 => i16_min + | I32 => i32_min + | I64 => i64_min + | I128 => i128_min + | Usize => usize_min + | U8 => u8_min + | U16 => u16_min + | U32 => u32_min + | U64 => u64_min + | U128 => u128_min +end. + +Definition scalar_max (ty: scalar_ty) : Z := + match ty with + | Isize => isize_max + | I8 => i8_max + | I16 => i16_max + | I32 => i32_max + | I64 => i64_max + | I128 => i128_max + | Usize => usize_max + | U8 => u8_max + | U16 => u16_max + | U32 => u32_max + | U64 => u64_max + | U128 => u128_max +end. + +(** We use the following conservative bounds to make sure we can compute bound + checks in most situations *) +Definition scalar_min_cons (ty: scalar_ty) : Z := + match ty with + | Isize => i32_min + | Usize => u32_min + | _ => scalar_min ty +end. + +Definition scalar_max_cons (ty: scalar_ty) : Z := + match ty with + | Isize => i32_max + | Usize => u32_max + | _ => scalar_max ty +end. + +Lemma scalar_min_cons_valid : forall ty, scalar_min ty <= scalar_min_cons ty . +Proof. + destruct ty; unfold scalar_min_cons, scalar_min; try lia. + - pose isize_min_bound; lia. + - apply Z.le_refl. +Qed. + +Lemma scalar_max_cons_valid : forall ty, scalar_max ty >= scalar_max_cons ty . +Proof. + destruct ty; unfold scalar_max_cons, scalar_max; try lia. + - pose isize_max_bound; lia. + - pose usize_max_bound. lia. +Qed. + +Definition scalar (ty: scalar_ty) : Type := + { x: Z | scalar_min ty <= x <= scalar_max ty }. + +Definition to_Z {ty} (x: scalar ty) : Z := proj1_sig x. + +(** Bounds checks: we start by using the conservative bounds, to make sure we + can compute in most situations, then we use the real bounds (for [isize] + and [usize]). *) +Definition scalar_ge_min (ty: scalar_ty) (x: Z) : bool := + Z.leb (scalar_min_cons ty) x || Z.leb (scalar_min ty) x. + +Definition scalar_le_max (ty: scalar_ty) (x: Z) : bool := + Z.leb x (scalar_max_cons ty) || Z.leb x (scalar_max ty). + +Lemma scalar_ge_min_valid (ty: scalar_ty) (x: Z) : + scalar_ge_min ty x = true -> scalar_min ty <= x . +Proof. + unfold scalar_ge_min. + pose (scalar_min_cons_valid ty). + lia. +Qed. + +Lemma scalar_le_max_valid (ty: scalar_ty) (x: Z) : + scalar_le_max ty x = true -> x <= scalar_max ty . +Proof. + unfold scalar_le_max. + pose (scalar_max_cons_valid ty). + lia. +Qed. + +Definition scalar_in_bounds (ty: scalar_ty) (x: Z) : bool := + scalar_ge_min ty x && scalar_le_max ty x . + +Lemma scalar_in_bounds_valid (ty: scalar_ty) (x: Z) : + scalar_in_bounds ty x = true -> scalar_min ty <= x <= scalar_max ty . +Proof. + unfold scalar_in_bounds. + intros H. + destruct (scalar_ge_min ty x) eqn:Hmin. + - destruct (scalar_le_max ty x) eqn:Hmax. + + pose (scalar_ge_min_valid ty x Hmin). + pose (scalar_le_max_valid ty x Hmax). + lia. + + inversion H. + - inversion H. +Qed. + +Import Sumbool. + +Definition mk_scalar (ty: scalar_ty) (x: Z) : result (scalar ty) := + match sumbool_of_bool (scalar_in_bounds ty x) with + | left H => Return (exist _ x (scalar_in_bounds_valid _ _ H)) + | right _ => Fail_ + end. + +Definition scalar_add {ty} (x y: scalar ty) : result (scalar ty) := mk_scalar ty (to_Z x + to_Z y). + +Definition scalar_sub {ty} (x y: scalar ty) : result (scalar ty) := mk_scalar ty (to_Z x - to_Z y). + +Definition scalar_mul {ty} (x y: scalar ty) : result (scalar ty) := mk_scalar ty (to_Z x * to_Z y). + +Definition scalar_div {ty} (x y: scalar ty) : result (scalar ty) := + if to_Z y =? 0 then Fail_ else + mk_scalar ty (to_Z x / to_Z y). + +Definition scalar_rem {ty} (x y: scalar ty) : result (scalar ty) := mk_scalar ty (Z.rem (to_Z x) (to_Z y)). + +Definition scalar_neg {ty} (x: scalar ty) : result (scalar ty) := mk_scalar ty (-(to_Z x)). + +(** Cast an integer from a [src_ty] to a [tgt_ty] *) +(* TODO: check the semantics of casts in Rust *) +Definition scalar_cast (src_ty tgt_ty : scalar_ty) (x : scalar src_ty) : result (scalar tgt_ty) := + mk_scalar tgt_ty (to_Z x). + +(** Comparisons *) +Print Z.leb . + +Definition scalar_leb {ty : scalar_ty} (x : scalar ty) (y : scalar ty) : bool := + Z.leb (to_Z x) (to_Z y) . + +Definition scalar_ltb {ty : scalar_ty} (x : scalar ty) (y : scalar ty) : bool := + Z.ltb (to_Z x) (to_Z y) . + +Definition scalar_geb {ty : scalar_ty} (x : scalar ty) (y : scalar ty) : bool := + Z.geb (to_Z x) (to_Z y) . + +Definition scalar_gtb {ty : scalar_ty} (x : scalar ty) (y : scalar ty) : bool := + Z.gtb (to_Z x) (to_Z y) . + +Definition scalar_eqb {ty : scalar_ty} (x : scalar ty) (y : scalar ty) : bool := + Z.eqb (to_Z x) (to_Z y) . + +Definition scalar_neqb {ty : scalar_ty} (x : scalar ty) (y : scalar ty) : bool := + negb (Z.eqb (to_Z x) (to_Z y)) . + + +(** The scalar types *) +Definition isize := scalar Isize. +Definition i8 := scalar I8. +Definition i16 := scalar I16. +Definition i32 := scalar I32. +Definition i64 := scalar I64. +Definition i128 := scalar I128. +Definition usize := scalar Usize. +Definition u8 := scalar U8. +Definition u16 := scalar U16. +Definition u32 := scalar U32. +Definition u64 := scalar U64. +Definition u128 := scalar U128. + +(** Negaion *) +Definition isize_neg := @scalar_neg Isize. +Definition i8_neg := @scalar_neg I8. +Definition i16_neg := @scalar_neg I16. +Definition i32_neg := @scalar_neg I32. +Definition i64_neg := @scalar_neg I64. +Definition i128_neg := @scalar_neg I128. + +(** Division *) +Definition isize_div := @scalar_div Isize. +Definition i8_div := @scalar_div I8. +Definition i16_div := @scalar_div I16. +Definition i32_div := @scalar_div I32. +Definition i64_div := @scalar_div I64. +Definition i128_div := @scalar_div I128. +Definition usize_div := @scalar_div Usize. +Definition u8_div := @scalar_div U8. +Definition u16_div := @scalar_div U16. +Definition u32_div := @scalar_div U32. +Definition u64_div := @scalar_div U64. +Definition u128_div := @scalar_div U128. + +(** Remainder *) +Definition isize_rem := @scalar_rem Isize. +Definition i8_rem := @scalar_rem I8. +Definition i16_rem := @scalar_rem I16. +Definition i32_rem := @scalar_rem I32. +Definition i64_rem := @scalar_rem I64. +Definition i128_rem := @scalar_rem I128. +Definition usize_rem := @scalar_rem Usize. +Definition u8_rem := @scalar_rem U8. +Definition u16_rem := @scalar_rem U16. +Definition u32_rem := @scalar_rem U32. +Definition u64_rem := @scalar_rem U64. +Definition u128_rem := @scalar_rem U128. + +(** Addition *) +Definition isize_add := @scalar_add Isize. +Definition i8_add := @scalar_add I8. +Definition i16_add := @scalar_add I16. +Definition i32_add := @scalar_add I32. +Definition i64_add := @scalar_add I64. +Definition i128_add := @scalar_add I128. +Definition usize_add := @scalar_add Usize. +Definition u8_add := @scalar_add U8. +Definition u16_add := @scalar_add U16. +Definition u32_add := @scalar_add U32. +Definition u64_add := @scalar_add U64. +Definition u128_add := @scalar_add U128. + +(** Substraction *) +Definition isize_sub := @scalar_sub Isize. +Definition i8_sub := @scalar_sub I8. +Definition i16_sub := @scalar_sub I16. +Definition i32_sub := @scalar_sub I32. +Definition i64_sub := @scalar_sub I64. +Definition i128_sub := @scalar_sub I128. +Definition usize_sub := @scalar_sub Usize. +Definition u8_sub := @scalar_sub U8. +Definition u16_sub := @scalar_sub U16. +Definition u32_sub := @scalar_sub U32. +Definition u64_sub := @scalar_sub U64. +Definition u128_sub := @scalar_sub U128. + +(** Multiplication *) +Definition isize_mul := @scalar_mul Isize. +Definition i8_mul := @scalar_mul I8. +Definition i16_mul := @scalar_mul I16. +Definition i32_mul := @scalar_mul I32. +Definition i64_mul := @scalar_mul I64. +Definition i128_mul := @scalar_mul I128. +Definition usize_mul := @scalar_mul Usize. +Definition u8_mul := @scalar_mul U8. +Definition u16_mul := @scalar_mul U16. +Definition u32_mul := @scalar_mul U32. +Definition u64_mul := @scalar_mul U64. +Definition u128_mul := @scalar_mul U128. + +(** Small utility *) +Definition usize_to_nat (x: usize) : nat := Z.to_nat (to_Z x). + +(** Notations *) +Notation "x %isize" := ((mk_scalar Isize x)%return) (at level 9). +Notation "x %i8" := ((mk_scalar I8 x)%return) (at level 9). +Notation "x %i16" := ((mk_scalar I16 x)%return) (at level 9). +Notation "x %i32" := ((mk_scalar I32 x)%return) (at level 9). +Notation "x %i64" := ((mk_scalar I64 x)%return) (at level 9). +Notation "x %i128" := ((mk_scalar I128 x)%return) (at level 9). +Notation "x %usize" := ((mk_scalar Usize x)%return) (at level 9). +Notation "x %u8" := ((mk_scalar U8 x)%return) (at level 9). +Notation "x %u16" := ((mk_scalar U16 x)%return) (at level 9). +Notation "x %u32" := ((mk_scalar U32 x)%return) (at level 9). +Notation "x %u64" := ((mk_scalar U64 x)%return) (at level 9). +Notation "x %u128" := ((mk_scalar U128 x)%return) (at level 9). + +Notation "x s= y" := (scalar_eqb x y) (at level 80) : Primitives_scope. +Notation "x s<> y" := (scalar_neqb x y) (at level 80) : Primitives_scope. +Notation "x s<= y" := (scalar_leb x y) (at level 80) : Primitives_scope. +Notation "x s< y" := (scalar_ltb x y) (at level 80) : Primitives_scope. +Notation "x s>= y" := (scalar_geb x y) (at level 80) : Primitives_scope. +Notation "x s> y" := (scalar_gtb x y) (at level 80) : Primitives_scope. + +(*** Vectors *) + +Definition vec T := { l: list T | Z.of_nat (length l) <= usize_max }. + +Definition vec_to_list {T: Type} (v: vec T) : list T := proj1_sig v. + +Definition vec_length {T: Type} (v: vec T) : Z := Z.of_nat (length (vec_to_list v)). + +Lemma le_0_usize_max : 0 <= usize_max. +Proof. + pose (H := usize_max_bound). + unfold u32_max in H. + lia. +Qed. + +Definition vec_new (T: Type) : vec T := (exist _ [] le_0_usize_max). + +Lemma vec_len_in_usize {T} (v: vec T) : usize_min <= vec_length v <= usize_max. +Proof. + unfold vec_length, usize_min. + split. + - lia. + - apply (proj2_sig v). +Qed. + +Definition vec_len (T: Type) (v: vec T) : usize := + exist _ (vec_length v) (vec_len_in_usize v). + +Fixpoint list_update {A} (l: list A) (n: nat) (a: A) + : list A := + match l with + | [] => [] + | x :: t => match n with + | 0%nat => a :: t + | S m => x :: (list_update t m a) +end end. + +Definition vec_bind {A B} (v: vec A) (f: list A -> result (list B)) : result (vec B) := + l <- f (vec_to_list v) ; + match sumbool_of_bool (scalar_le_max Usize (Z.of_nat (length l))) with + | left H => Return (exist _ l (scalar_le_max_valid _ _ H)) + | right _ => Fail_ + end. + +(* The **forward** function shouldn't be used *) +Definition vec_push_fwd (T: Type) (v: vec T) (x: T) : unit := tt. + +Definition vec_push_back (T: Type) (v: vec T) (x: T) : result (vec T) := + vec_bind v (fun l => Return (l ++ [x])). + +(* The **forward** function shouldn't be used *) +Definition vec_insert_fwd (T: Type) (v: vec T) (i: usize) (x: T) : result unit := + if to_Z i <? vec_length v then Return tt else Fail_. + +Definition vec_insert_back (T: Type) (v: vec T) (i: usize) (x: T) : result (vec T) := + vec_bind v (fun l => + if to_Z i <? Z.of_nat (length l) + then Return (list_update l (usize_to_nat i) x) + else Fail_). + +(* The **backward** function shouldn't be used *) +Definition vec_index_fwd (T: Type) (v: vec T) (i: usize) : result T := + match nth_error (vec_to_list v) (usize_to_nat i) with + | Some n => Return n + | None => Fail_ + end. + +Definition vec_index_back (T: Type) (v: vec T) (i: usize) (x: T) : result unit := + if to_Z i <? vec_length v then Return tt else Fail_. + +(* The **backward** function shouldn't be used *) +Definition vec_index_mut_fwd (T: Type) (v: vec T) (i: usize) : result T := + match nth_error (vec_to_list v) (usize_to_nat i) with + | Some n => Return n + | None => Fail_ + end. + +Definition vec_index_mut_back (T: Type) (v: vec T) (i: usize) (x: T) : result (vec T) := + vec_bind v (fun l => + if to_Z i <? Z.of_nat (length l) + then Return (list_update l (usize_to_nat i) x) + else Fail_). + +End Primitives. |