import Lean import Lean.Meta.Tactic.Simp import Mathlib.Tactic.Linarith import Base.Primitives.Base import Base.Diverge.Base import Base.Progress.Base import Base.Arith.Int namespace Primitives ---------------------- -- MACHINE INTEGERS -- ---------------------- -- We redefine our machine integers types. -- For Isize/Usize, we reuse `getNumBits` from `USize`. You cannot reduce `getNumBits` -- using the simplifier, meaning that proofs do not depend on the compile-time value of -- USize.size. (Lean assumes 32 or 64-bit platforms, and Rust doesn't really support, at -- least officially, 16-bit microcontrollers, so this seems like a fine design decision -- for now.) -- Note from Chris Bailey: "If there's more than one salient property of your -- definition then the subtyping strategy might get messy, and the property part -- of a subtype is less discoverable by the simplifier or tactics like -- library_search." So, we will not add refinements on the return values of the -- operations defined on Primitives, but will rather rely on custom lemmas to -- invert on possible return values of the primitive operations. -- Machine integer constants, done via `ofNatCore`, which requires a proof that -- the `Nat` fits within the desired integer type. We provide a custom tactic. open Result Error open System.Platform.getNumBits -- TODO: is there a way of only importing System.Platform.getNumBits? -- @[simp] def size_num_bits : Nat := (System.Platform.getNumBits ()).val -- Remark: Lean seems to use < for the comparisons with the upper bounds by convention. -- The "structured" bounds def Isize.smin : Int := - (HPow.hPow 2 (size_num_bits - 1)) def Isize.smax : Int := (HPow.hPow 2 (size_num_bits - 1)) - 1 def I8.smin : Int := - (HPow.hPow 2 7) def I8.smax : Int := HPow.hPow 2 7 - 1 def I16.smin : Int := - (HPow.hPow 2 15) def I16.smax : Int := HPow.hPow 2 15 - 1 def I32.smin : Int := -(HPow.hPow 2 31) def I32.smax : Int := HPow.hPow 2 31 - 1 def I64.smin : Int := -(HPow.hPow 2 63) def I64.smax : Int := HPow.hPow 2 63 - 1 def I128.smin : Int := -(HPow.hPow 2 127) def I128.smax : Int := HPow.hPow 2 127 - 1 def Usize.smin : Int := 0 def Usize.smax : Int := HPow.hPow 2 size_num_bits - 1 def U8.smin : Int := 0 def U8.smax : Int := HPow.hPow 2 8 - 1 def U16.smin : Int := 0 def U16.smax : Int := HPow.hPow 2 16 - 1 def U32.smin : Int := 0 def U32.smax : Int := HPow.hPow 2 32 - 1 def U64.smin : Int := 0 def U64.smax : Int := HPow.hPow 2 64 - 1 def U128.smin : Int := 0 def U128.smax : Int := HPow.hPow 2 128 - 1 -- The "normalized" bounds, that we use in practice def I8.min : Int := -128 def I8.max : Int := 127 def I16.min : Int := -32768 def I16.max : Int := 32767 def I32.min : Int := -2147483648 def I32.max : Int := 2147483647 def I64.min : Int := -9223372036854775808 def I64.max : Int := 9223372036854775807 def I128.min : Int := -170141183460469231731687303715884105728 def I128.max : Int := 170141183460469231731687303715884105727 @[simp] def U8.min : Int := 0 def U8.max : Int := 255 @[simp] def U16.min : Int := 0 def U16.max : Int := 65535 @[simp] def U32.min : Int := 0 def U32.max : Int := 4294967295 @[simp] def U64.min : Int := 0 def U64.max : Int := 18446744073709551615 @[simp] def U128.min : Int := 0 def U128.max : Int := 340282366920938463463374607431768211455 @[simp] def Usize.min : Int := 0 def Isize.refined_min : { n:Int // n = I32.min ∨ n = I64.min } := ⟨ Isize.smin, by simp [Isize.smin] cases System.Platform.numBits_eq <;> unfold System.Platform.numBits at * <;> simp [*] ⟩ def Isize.refined_max : { n:Int // n = I32.max ∨ n = I64.max } := ⟨ Isize.smax, by simp [Isize.smax] cases System.Platform.numBits_eq <;> unfold System.Platform.numBits at * <;> simp [*] ⟩ def Usize.refined_max : { n:Int // n = U32.max ∨ n = U64.max } := ⟨ Usize.smax, by simp [Usize.smax] cases System.Platform.numBits_eq <;> unfold System.Platform.numBits at * <;> simp [*] ⟩ def Isize.min := Isize.refined_min.val def Isize.max := Isize.refined_max.val def Usize.max := Usize.refined_max.val inductive ScalarTy := | Isize | I8 | I16 | I32 | I64 | I128 | Usize | U8 | U16 | U32 | U64 | U128 def ScalarTy.isSigned (ty : ScalarTy) : Bool := match ty with | Isize | I8 | I16 | I32 | I64 | I128 => true | Usize | U8 | U16 | U32 | U64 | U128 => false def Scalar.smin (ty : ScalarTy) : Int := match ty with | .Isize => Isize.smin | .I8 => I8.smin | .I16 => I16.smin | .I32 => I32.smin | .I64 => I64.smin | .I128 => I128.smin | .Usize => Usize.smin | .U8 => U8.smin | .U16 => U16.smin | .U32 => U32.smin | .U64 => U64.smin | .U128 => U128.smin def Scalar.smax (ty : ScalarTy) : Int := match ty with | .Isize => Isize.smax | .I8 => I8.smax | .I16 => I16.smax | .I32 => I32.smax | .I64 => I64.smax | .I128 => I128.smax | .Usize => Usize.smax | .U8 => U8.smax | .U16 => U16.smax | .U32 => U32.smax | .U64 => U64.smax | .U128 => U128.smax def Scalar.min (ty : ScalarTy) : Int := 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 def Scalar.max (ty : ScalarTy) : Int := 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 def Scalar.smin_eq (ty : ScalarTy) : Scalar.min ty = Scalar.smin ty := by cases ty <;> rfl def Scalar.smax_eq (ty : ScalarTy) : Scalar.max ty = Scalar.smax ty := by cases ty <;> rfl -- "Conservative" bounds -- We use those because we can't compare to the isize bounds (which can't -- reduce at compile-time). Whenever we perform an arithmetic operation like -- addition we need to check that the result is in bounds: we first compare -- to the conservative bounds, which reduce, then compare to the real bounds. -- This is useful for the various #asserts that we want to reduce at -- type-checking time. def Scalar.cMin (ty : ScalarTy) : Int := match ty with | .Isize => Scalar.min .I32 | _ => Scalar.min ty def Scalar.cMax (ty : ScalarTy) : Int := match ty with | .Isize => Scalar.max .I32 | .Usize => Scalar.max .U32 | _ => Scalar.max ty theorem Scalar.cMin_bound ty : Scalar.min ty ≤ Scalar.cMin ty := by cases ty <;> simp [Scalar.min, Scalar.max, Scalar.cMin, Scalar.cMax] at * have h := Isize.refined_min.property cases h <;> simp [*, Isize.min] theorem Scalar.cMax_bound ty : Scalar.cMax ty ≤ Scalar.max ty := by cases ty <;> simp [Scalar.min, Scalar.max, Scalar.cMin, Scalar.cMax] at * . have h := Isize.refined_max.property cases h <;> simp [*, Isize.max] . have h := Usize.refined_max.property cases h <;> simp [*, Usize.max] theorem Scalar.cMin_suffices ty (h : Scalar.cMin ty ≤ x) : Scalar.min ty ≤ x := by have := Scalar.cMin_bound ty linarith theorem Scalar.cMax_suffices ty (h : x ≤ Scalar.cMax ty) : x ≤ Scalar.max ty := by have := Scalar.cMax_bound ty linarith structure Scalar (ty : ScalarTy) where val : Int hmin : Scalar.min ty ≤ val hmax : val ≤ Scalar.max ty deriving Repr theorem Scalar.bound_suffices (ty : ScalarTy) (x : Int) : Scalar.cMin ty ≤ x ∧ x ≤ Scalar.cMax ty -> Scalar.min ty ≤ x ∧ x ≤ Scalar.max ty := λ h => by apply And.intro <;> have hmin := Scalar.cMin_bound ty <;> have hmax := Scalar.cMax_bound ty <;> linarith def Scalar.ofIntCore {ty : ScalarTy} (x : Int) (hmin : Scalar.min ty ≤ x) (hmax : x ≤ Scalar.max ty) : Scalar ty := { val := x, hmin := hmin, hmax := hmax } -- Tactic to prove that integers are in bounds -- TODO: use this: https://leanprover.zulipchat.com/#narrow/stream/270676-lean4/topic/instance.20with.20tactic.20autoparam syntax "intlit" : tactic macro_rules | `(tactic| intlit) => `(tactic| apply Scalar.bound_suffices; decide) def Scalar.ofInt {ty : ScalarTy} (x : Int) (h : Scalar.min ty ≤ x ∧ x ≤ Scalar.max ty := by intlit) : Scalar ty := -- Remark: we initially wrote: -- let ⟨ hmin, hmax ⟩ := h -- Scalar.ofIntCore x hmin hmax -- We updated to the line below because a similar pattern in `Scalar.tryMk` -- made reduction block. Both versions seem to work for `Scalar.ofInt`, though. -- TODO: investigate Scalar.ofIntCore x h.left h.right @[simp] def Scalar.check_bounds (ty : ScalarTy) (x : Int) : Bool := (Scalar.cMin ty ≤ x || Scalar.min ty ≤ x) ∧ (x ≤ Scalar.cMax ty || x ≤ Scalar.max ty) theorem Scalar.check_bounds_prop {ty : ScalarTy} {x : Int} (h: Scalar.check_bounds ty x) : Scalar.min ty ≤ x ∧ x ≤ Scalar.max ty := by simp at * have ⟨ hmin, hmax ⟩ := h have hbmin := Scalar.cMin_bound ty have hbmax := Scalar.cMax_bound ty cases hmin <;> cases hmax <;> apply And.intro <;> linarith -- Further thoughts: look at what has been done here: -- https://github.com/leanprover-community/mathlib4/blob/master/Mathlib/Data/Fin/Basic.lean -- and -- https://github.com/leanprover-community/mathlib4/blob/master/Mathlib/Data/UInt.lean -- which both contain a fair amount of reasoning already! def Scalar.tryMk (ty : ScalarTy) (x : Int) : Result (Scalar ty) := if h:Scalar.check_bounds ty x then -- If we do: -- ``` -- let ⟨ hmin, hmax ⟩ := (Scalar.check_bounds_prop h) -- Scalar.ofIntCore x hmin hmax -- ``` -- then normalization blocks (for instance, some proofs which use reflexivity fail). -- However, the version below doesn't block reduction (TODO: investigate): return Scalar.ofInt x (Scalar.check_bounds_prop h) else fail integerOverflow def Scalar.neg {ty : ScalarTy} (x : Scalar ty) : Result (Scalar ty) := Scalar.tryMk ty (- x.val) -- Our custom remainder operation, which satisfies the semantics of Rust -- TODO: is there a better way? def scalar_rem (x y : Int) : Int := if 0 ≤ x then x % y else - (|x| % |y|) @[simp] def scalar_rem_nonneg {x y : Int} (hx : 0 ≤ x) : scalar_rem x y = x % y := by intros simp [*, scalar_rem] -- Our custom division operation, which satisfies the semantics of Rust -- TODO: is there a better way? def scalar_div (x y : Int) : Int := if 0 ≤ x && 0 ≤ y then x / y else if 0 ≤ x && y < 0 then - (|x| / |y|) else if x < 0 && 0 ≤ y then - (|x| / |y|) else |x| / |y| @[simp] def scalar_div_nonneg {x y : Int} (hx : 0 ≤ x) (hy : 0 ≤ y) : scalar_div x y = x / y := by intros simp [*, scalar_div] -- Checking that the remainder operation is correct #assert scalar_rem 1 2 = 1 #assert scalar_rem (-1) 2 = -1 #assert scalar_rem 1 (-2) = 1 #assert scalar_rem (-1) (-2) = -1 #assert scalar_rem 7 3 = (1:Int) #assert scalar_rem (-7) 3 = -1 #assert scalar_rem 7 (-3) = 1 #assert scalar_rem (-7) (-3) = -1 -- Checking that the division operation is correct #assert scalar_div 3 2 = 1 #assert scalar_div (-3) 2 = -1 #assert scalar_div 3 (-2) = -1 #assert scalar_div (-3) (-2) = 1 #assert scalar_div 7 3 = 2 #assert scalar_div (-7) 3 = -2 #assert scalar_div 7 (-3) = -2 #assert scalar_div (-7) (-3) = 2 def Scalar.div {ty : ScalarTy} (x : Scalar ty) (y : Scalar ty) : Result (Scalar ty) := if y.val != 0 then Scalar.tryMk ty (scalar_div x.val y.val) else fail divisionByZero def Scalar.rem {ty : ScalarTy} (x : Scalar ty) (y : Scalar ty) : Result (Scalar ty) := if y.val != 0 then Scalar.tryMk ty (scalar_rem x.val y.val) else fail divisionByZero def Scalar.add {ty : ScalarTy} (x : Scalar ty) (y : Scalar ty) : Result (Scalar ty) := Scalar.tryMk ty (x.val + y.val) def Scalar.sub {ty : ScalarTy} (x : Scalar ty) (y : Scalar ty) : Result (Scalar ty) := Scalar.tryMk ty (x.val - y.val) def Scalar.mul {ty : ScalarTy} (x : Scalar ty) (y : Scalar ty) : Result (Scalar ty) := Scalar.tryMk ty (x.val * y.val) -- TODO: instances of +, -, * etc. for scalars -- Cast an integer from a [src_ty] to a [tgt_ty] -- TODO: check the semantics of casts in Rust def Scalar.cast {src_ty : ScalarTy} (tgt_ty : ScalarTy) (x : Scalar src_ty) : Result (Scalar tgt_ty) := Scalar.tryMk tgt_ty x.val -- The scalar types -- We declare the definitions as reducible so that Lean can unfold them (useful -- for type class resolution for instance). @[reducible] def Isize := Scalar .Isize @[reducible] def I8 := Scalar .I8 @[reducible] def I16 := Scalar .I16 @[reducible] def I32 := Scalar .I32 @[reducible] def I64 := Scalar .I64 @[reducible] def I128 := Scalar .I128 @[reducible] def Usize := Scalar .Usize @[reducible] def U8 := Scalar .U8 @[reducible] def U16 := Scalar .U16 @[reducible] def U32 := Scalar .U32 @[reducible] def U64 := Scalar .U64 @[reducible] def U128 := Scalar .U128 -- TODO: below: not sure this is the best way. -- Should we rather overload operations like +, -, etc.? -- Also, it is possible to automate the generation of those definitions -- with macros (but would it be a good idea? It would be less easy to -- read the file, which is not supposed to change a lot) -- Negation /-- Remark: there is no heterogeneous negation in the Lean prelude: we thus introduce one here. The notation typeclass for heterogeneous addition. This enables the notation `- a : β` where `a : α`. -/ class HNeg (α : Type u) (β : outParam (Type v)) where /-- `- a` computes the negation of `a`. The meaning of this notation is type-dependent. -/ hNeg : α → β prefix:75 "-" => HNeg.hNeg instance : HNeg Isize (Result Isize) where hNeg x := Scalar.neg x instance : HNeg I8 (Result I8) where hNeg x := Scalar.neg x instance : HNeg I16 (Result I16) where hNeg x := Scalar.neg x instance : HNeg I32 (Result I32) where hNeg x := Scalar.neg x instance : HNeg I64 (Result I64) where hNeg x := Scalar.neg x instance : HNeg I128 (Result I128) where hNeg x := Scalar.neg x -- Addition instance {ty} : HAdd (Scalar ty) (Scalar ty) (Result (Scalar ty)) where hAdd x y := Scalar.add x y -- Substraction instance {ty} : HSub (Scalar ty) (Scalar ty) (Result (Scalar ty)) where hSub x y := Scalar.sub x y -- Multiplication instance {ty} : HMul (Scalar ty) (Scalar ty) (Result (Scalar ty)) where hMul x y := Scalar.mul x y -- Division instance {ty} : HDiv (Scalar ty) (Scalar ty) (Result (Scalar ty)) where hDiv x y := Scalar.div x y -- Remainder instance {ty} : HMod (Scalar ty) (Scalar ty) (Result (Scalar ty)) where hMod x y := Scalar.rem x y -- Generic theorem - shouldn't be used much @[cpspec] theorem Scalar.add_spec {ty} {x y : Scalar ty} (hmin : Scalar.min ty ≤ x.val + y.val) (hmax : x.val + y.val ≤ Scalar.max ty) : ∃ z, x + y = ret z ∧ z.val = x.val + y.val := by simp [HAdd.hAdd, add, Add.add] simp [tryMk] split . simp [pure] rfl . tauto theorem Scalar.add_unsigned_spec {ty} (s: ¬ ty.isSigned) {x y : Scalar ty} (hmax : x.val + y.val ≤ Scalar.max ty) : ∃ z, x + y = ret z ∧ z.val = x.val + y.val := by have hmin : Scalar.min ty ≤ x.val + y.val := by have hx := x.hmin have hy := y.hmin cases ty <;> simp [min] at * <;> linarith apply add_spec <;> assumption /- Fine-grained theorems -/ @[cepspec] theorem Usize.add_spec {x y : Usize} (hmax : x.val + y.val ≤ Usize.max) : ∃ z, x + y = ret z ∧ z.val = x.val + y.val := by apply Scalar.add_unsigned_spec <;> simp only [Scalar.max, *] @[cepspec] theorem U8.add_spec {x y : U8} (hmax : x.val + y.val ≤ U8.max) : ∃ z, x + y = ret z ∧ z.val = x.val + y.val := by apply Scalar.add_unsigned_spec <;> simp only [Scalar.max, *] @[cepspec] theorem U16.add_spec {x y : U16} (hmax : x.val + y.val ≤ U16.max) : ∃ z, x + y = ret z ∧ z.val = x.val + y.val := by apply Scalar.add_unsigned_spec <;> simp only [Scalar.max, *] @[cepspec] theorem U32.add_spec {x y : U32} (hmax : x.val + y.val ≤ U32.max) : ∃ z, x + y = ret z ∧ z.val = x.val + y.val := by apply Scalar.add_unsigned_spec <;> simp only [Scalar.max, *] @[cepspec] theorem U64.add_spec {x y : U64} (hmax : x.val + y.val ≤ U64.max) : ∃ z, x + y = ret z ∧ z.val = x.val + y.val := by apply Scalar.add_unsigned_spec <;> simp only [Scalar.max, *] @[cepspec] theorem U128.add_spec {x y : U128} (hmax : x.val + y.val ≤ U128.max) : ∃ z, x + y = ret z ∧ z.val = x.val + y.val := by apply Scalar.add_unsigned_spec <;> simp only [Scalar.max, *] -- Generic theorem - shouldn't be used much @[cpspec] theorem Scalar.sub_spec {ty} {x y : Scalar ty} (hmin : Scalar.min ty ≤ x.val - y.val) (hmax : x.val - y.val ≤ Scalar.max ty) : ∃ z, x - y = ret z ∧ z.val = x.val - y.val := by simp [HSub.hSub, sub, Sub.sub] simp [tryMk] split . simp [pure] rfl . tauto theorem Scalar.sub_unsigned_spec {ty} (s: ¬ ty.isSigned) {x y : Scalar ty} (hmin : Scalar.min ty ≤ x.val - y.val) : ∃ z, x - y = ret z ∧ z.val = x.val - y.val := by have : x.val - y.val ≤ Scalar.max ty := by have hx := x.hmin have hxm := x.hmax have hy := y.hmin cases ty <;> simp [min, max] at * <;> linarith intros apply sub_spec <;> assumption /- Fine-grained theorems -/ @[cepspec] theorem Usize.sub_spec {x y : Usize} (hmin : Usize.min ≤ x.val - y.val) : ∃ z, x - y = ret z ∧ z.val = x.val - y.val := by apply Scalar.sub_unsigned_spec <;> simp only [Scalar.min, *] @[cepspec] theorem U8.sub_spec {x y : U8} (hmin : U8.min ≤ x.val - y.val) : ∃ z, x - y = ret z ∧ z.val = x.val - y.val := by apply Scalar.sub_unsigned_spec <;> simp only [Scalar.min, *] @[cepspec] theorem U16.sub_spec {x y : U16} (hmin : U16.min ≤ x.val - y.val) : ∃ z, x - y = ret z ∧ z.val = x.val - y.val := by apply Scalar.sub_unsigned_spec <;> simp only [Scalar.min, *] @[cepspec] theorem U32.sub_spec {x y : U32} (hmin : U32.min ≤ x.val - y.val) : ∃ z, x - y = ret z ∧ z.val = x.val - y.val := by apply Scalar.sub_unsigned_spec <;> simp only [Scalar.min, *] @[cepspec] theorem U64.sub_spec {x y : U64} (hmin : U64.min ≤ x.val - y.val) : ∃ z, x - y = ret z ∧ z.val = x.val - y.val := by apply Scalar.sub_unsigned_spec <;> simp only [Scalar.min, *] @[cepspec] theorem U128.sub_spec {x y : U128} (hmin : U128.min ≤ x.val - y.val) : ∃ z, x - y = ret z ∧ z.val = x.val - y.val := by apply Scalar.sub_unsigned_spec <;> simp only [Scalar.min, *] -- Generic theorem - shouldn't be used much theorem Scalar.mul_spec {ty} {x y : Scalar ty} (hmin : Scalar.min ty ≤ x.val * y.val) (hmax : x.val * y.val ≤ Scalar.max ty) : ∃ z, x * y = ret z ∧ z.val = x.val * y.val := by simp [HMul.hMul, mul, Mul.mul] simp [tryMk] split . simp [pure] rfl . tauto theorem Scalar.mul_unsigned_spec {ty} (s: ¬ ty.isSigned) {x y : Scalar ty} (hmax : x.val * y.val ≤ Scalar.max ty) : ∃ z, x * y = ret z ∧ z.val = x.val * y.val := by have : Scalar.min ty ≤ x.val * y.val := by have hx := x.hmin have hy := y.hmin cases ty <;> simp at * <;> apply mul_nonneg hx hy apply mul_spec <;> assumption /- Fine-grained theorems -/ @[cepspec] theorem Usize.mul_spec {x y : Usize} (hmax : x.val * y.val ≤ Usize.max) : ∃ z, x * y = ret z ∧ z.val = x.val * y.val := by apply Scalar.mul_unsigned_spec <;> simp only [Scalar.max, *] @[cepspec] theorem U8.mul_spec {x y : U8} (hmax : x.val * y.val ≤ U8.max) : ∃ z, x * y = ret z ∧ z.val = x.val * y.val := by apply Scalar.mul_unsigned_spec <;> simp only [Scalar.max, *] @[cepspec] theorem U16.mul_spec {x y : U16} (hmax : x.val * y.val ≤ U16.max) : ∃ z, x * y = ret z ∧ z.val = x.val * y.val := by apply Scalar.mul_unsigned_spec <;> simp only [Scalar.max, *] @[cepspec] theorem U32.mul_spec {x y : U32} (hmax : x.val * y.val ≤ U32.max) : ∃ z, x * y = ret z ∧ z.val = x.val * y.val := by apply Scalar.mul_unsigned_spec <;> simp only [Scalar.max, *] @[cepspec] theorem U64.mul_spec {x y : U64} (hmax : x.val * y.val ≤ U64.max) : ∃ z, x * y = ret z ∧ z.val = x.val * y.val := by apply Scalar.mul_unsigned_spec <;> simp only [Scalar.max, *] @[cepspec] theorem U128.mul_spec {x y : U128} (hmax : x.val * y.val ≤ U128.max) : ∃ z, x * y = ret z ∧ z.val = x.val * y.val := by apply Scalar.mul_unsigned_spec <;> simp only [Scalar.max, *] -- Generic theorem - shouldn't be used much @[cpspec] theorem Scalar.div_spec {ty} {x y : Scalar ty} (hnz : y.val ≠ 0) (hmin : Scalar.min ty ≤ scalar_div x.val y.val) (hmax : scalar_div x.val y.val ≤ Scalar.max ty) : ∃ z, x / y = ret z ∧ z.val = scalar_div x.val y.val := by simp [HDiv.hDiv, div, Div.div] simp [tryMk, *] simp [pure] rfl theorem Scalar.div_unsigned_spec {ty} (s: ¬ ty.isSigned) (x : Scalar ty) {y : Scalar ty} (hnz : y.val ≠ 0) : ∃ z, x / y = ret z ∧ z.val = x.val / y.val := by have h : Scalar.min ty = 0 := by cases ty <;> simp at * have hx := x.hmin have hy := y.hmin simp [h] at hx hy have hmin : 0 ≤ x.val / y.val := Int.ediv_nonneg hx hy have hmax : x.val / y.val ≤ Scalar.max ty := by have := Int.ediv_le_self y.val hx have := x.hmax linarith have hs := @div_spec ty x y hnz simp [*] at hs apply hs /- Fine-grained theorems -/ @[cepspec] theorem Usize.div_spec (x : Usize) {y : Usize} (hnz : y.val ≠ 0) : ∃ z, x / y = ret z ∧ z.val = x.val / y.val := by apply Scalar.div_unsigned_spec <;> simp [*] @[cepspec] theorem U8.div_spec (x : U8) {y : U8} (hnz : y.val ≠ 0) : ∃ z, x / y = ret z ∧ z.val = x.val / y.val := by apply Scalar.div_unsigned_spec <;> simp [Scalar.max, *] @[cepspec] theorem U16.div_spec (x : U16) {y : U16} (hnz : y.val ≠ 0) : ∃ z, x / y = ret z ∧ z.val = x.val / y.val := by apply Scalar.div_unsigned_spec <;> simp [Scalar.max, *] @[cepspec] theorem U32.div_spec (x : U32) {y : U32} (hnz : y.val ≠ 0) : ∃ z, x / y = ret z ∧ z.val = x.val / y.val := by apply Scalar.div_unsigned_spec <;> simp [Scalar.max, *] @[cepspec] theorem U64.div_spec (x : U64) {y : U64} (hnz : y.val ≠ 0) : ∃ z, x / y = ret z ∧ z.val = x.val / y.val := by apply Scalar.div_unsigned_spec <;> simp [Scalar.max, *] @[cepspec] theorem U128.div_spec (x : U128) {y : U128} (hnz : y.val ≠ 0) : ∃ z, x / y = ret z ∧ z.val = x.val / y.val := by apply Scalar.div_unsigned_spec <;> simp [Scalar.max, *] -- Generic theorem - shouldn't be used much @[cpspec] theorem Scalar.rem_spec {ty} {x y : Scalar ty} (hnz : y.val ≠ 0) (hmin : Scalar.min ty ≤ scalar_rem x.val y.val) (hmax : scalar_rem x.val y.val ≤ Scalar.max ty) : ∃ z, x % y = ret z ∧ z.val = scalar_rem x.val y.val := by simp [HMod.hMod, rem] simp [tryMk, *] simp [pure] rfl theorem Scalar.rem_unsigned_spec {ty} (s: ¬ ty.isSigned) (x : Scalar ty) {y : Scalar ty} (hnz : y.val ≠ 0) : ∃ z, x % y = ret z ∧ z.val = x.val % y.val := by have h : Scalar.min ty = 0 := by cases ty <;> simp at * have hx := x.hmin have hy := y.hmin simp [h] at hx hy have hmin : 0 ≤ x.val % y.val := Int.emod_nonneg x.val hnz have hmax : x.val % y.val ≤ Scalar.max ty := by have h : 0 < y.val := by int_tac have h := Int.emod_lt_of_pos x.val h have := y.hmax linarith have hs := @rem_spec ty x y hnz simp [*] at hs simp [*] @[cepspec] theorem Usize.rem_spec (x : Usize) {y : Usize} (hnz : y.val ≠ 0) : ∃ z, x % y = ret z ∧ z.val = x.val % y.val := by apply Scalar.rem_unsigned_spec <;> simp [*] @[cepspec] theorem U8.rem_spec (x : U8) {y : U8} (hnz : y.val ≠ 0) : ∃ z, x % y = ret z ∧ z.val = x.val % y.val := by apply Scalar.rem_unsigned_spec <;> simp [Scalar.max, *] @[cepspec] theorem U16.rem_spec (x : U16) {y : U16} (hnz : y.val ≠ 0) : ∃ z, x % y = ret z ∧ z.val = x.val % y.val := by apply Scalar.rem_unsigned_spec <;> simp [Scalar.max, *] @[cepspec] theorem U32.rem_spec (x : U32) {y : U32} (hnz : y.val ≠ 0) : ∃ z, x % y = ret z ∧ z.val = x.val % y.val := by apply Scalar.rem_unsigned_spec <;> simp [Scalar.max, *] @[cepspec] theorem U64.rem_spec (x : U64) {y : U64} (hnz : y.val ≠ 0) : ∃ z, x % y = ret z ∧ z.val = x.val % y.val := by apply Scalar.rem_unsigned_spec <;> simp [Scalar.max, *] @[cepspec] theorem U128.rem_spec (x : U128) {y : U128} (hnz : y.val ≠ 0) : ∃ z, x % y = ret z ∧ z.val = x.val % y.val := by apply Scalar.rem_unsigned_spec <;> simp [Scalar.max, *] -- ofIntCore -- TODO: typeclass? def Isize.ofIntCore := @Scalar.ofIntCore .Isize def I8.ofIntCore := @Scalar.ofIntCore .I8 def I16.ofIntCore := @Scalar.ofIntCore .I16 def I32.ofIntCore := @Scalar.ofIntCore .I32 def I64.ofIntCore := @Scalar.ofIntCore .I64 def I128.ofIntCore := @Scalar.ofIntCore .I128 def Usize.ofIntCore := @Scalar.ofIntCore .Usize def U8.ofIntCore := @Scalar.ofIntCore .U8 def U16.ofIntCore := @Scalar.ofIntCore .U16 def U32.ofIntCore := @Scalar.ofIntCore .U32 def U64.ofIntCore := @Scalar.ofIntCore .U64 def U128.ofIntCore := @Scalar.ofIntCore .U128 -- ofInt -- TODO: typeclass? def Isize.ofInt := @Scalar.ofInt .Isize def I8.ofInt := @Scalar.ofInt .I8 def I16.ofInt := @Scalar.ofInt .I16 def I32.ofInt := @Scalar.ofInt .I32 def I64.ofInt := @Scalar.ofInt .I64 def I128.ofInt := @Scalar.ofInt .I128 def Usize.ofInt := @Scalar.ofInt .Usize def U8.ofInt := @Scalar.ofInt .U8 def U16.ofInt := @Scalar.ofInt .U16 def U32.ofInt := @Scalar.ofInt .U32 def U64.ofInt := @Scalar.ofInt .U64 def U128.ofInt := @Scalar.ofInt .U128 -- TODO: factor those lemmas out @[simp] theorem Scalar.ofInt_val_eq {ty} (h : Scalar.min ty ≤ x ∧ x ≤ Scalar.max ty) : (Scalar.ofInt x h).val = x := by simp [Scalar.ofInt, Scalar.ofIntCore] @[simp] theorem Isize.ofInt_val_eq (h : Scalar.min ScalarTy.Isize ≤ x ∧ x ≤ Scalar.max ScalarTy.Isize) : (Isize.ofInt x h).val = x := by apply Scalar.ofInt_val_eq h @[simp] theorem I8.ofInt_val_eq (h : Scalar.min ScalarTy.I8 ≤ x ∧ x ≤ Scalar.max ScalarTy.I8) : (I8.ofInt x h).val = x := by apply Scalar.ofInt_val_eq h @[simp] theorem I16.ofInt_val_eq (h : Scalar.min ScalarTy.I16 ≤ x ∧ x ≤ Scalar.max ScalarTy.I16) : (I16.ofInt x h).val = x := by apply Scalar.ofInt_val_eq h @[simp] theorem I32.ofInt_val_eq (h : Scalar.min ScalarTy.I32 ≤ x ∧ x ≤ Scalar.max ScalarTy.I32) : (I32.ofInt x h).val = x := by apply Scalar.ofInt_val_eq h @[simp] theorem I64.ofInt_val_eq (h : Scalar.min ScalarTy.I64 ≤ x ∧ x ≤ Scalar.max ScalarTy.I64) : (I64.ofInt x h).val = x := by apply Scalar.ofInt_val_eq h @[simp] theorem I128.ofInt_val_eq (h : Scalar.min ScalarTy.I128 ≤ x ∧ x ≤ Scalar.max ScalarTy.I128) : (I128.ofInt x h).val = x := by apply Scalar.ofInt_val_eq h @[simp] theorem Usize.ofInt_val_eq (h : Scalar.min ScalarTy.Usize ≤ x ∧ x ≤ Scalar.max ScalarTy.Usize) : (Usize.ofInt x h).val = x := by apply Scalar.ofInt_val_eq h @[simp] theorem U8.ofInt_val_eq (h : Scalar.min ScalarTy.U8 ≤ x ∧ x ≤ Scalar.max ScalarTy.U8) : (U8.ofInt x h).val = x := by apply Scalar.ofInt_val_eq h @[simp] theorem U16.ofInt_val_eq (h : Scalar.min ScalarTy.U16 ≤ x ∧ x ≤ Scalar.max ScalarTy.U16) : (U16.ofInt x h).val = x := by apply Scalar.ofInt_val_eq h @[simp] theorem U32.ofInt_val_eq (h : Scalar.min ScalarTy.U32 ≤ x ∧ x ≤ Scalar.max ScalarTy.U32) : (U32.ofInt x h).val = x := by apply Scalar.ofInt_val_eq h @[simp] theorem U64.ofInt_val_eq (h : Scalar.min ScalarTy.U64 ≤ x ∧ x ≤ Scalar.max ScalarTy.U64) : (U64.ofInt x h).val = x := by apply Scalar.ofInt_val_eq h @[simp] theorem U128.ofInt_val_eq (h : Scalar.min ScalarTy.U128 ≤ x ∧ x ≤ Scalar.max ScalarTy.U128) : (U128.ofInt x h).val = x := by apply Scalar.ofInt_val_eq h -- Comparisons instance {ty} : LT (Scalar ty) where lt a b := LT.lt a.val b.val instance {ty} : LE (Scalar ty) where le a b := LE.le a.val b.val instance Scalar.decLt {ty} (a b : Scalar ty) : Decidable (LT.lt a b) := Int.decLt .. instance Scalar.decLe {ty} (a b : Scalar ty) : Decidable (LE.le a b) := Int.decLe .. theorem Scalar.eq_of_val_eq {ty} : ∀ {i j : Scalar ty}, Eq i.val j.val → Eq i j | ⟨_, _, _⟩, ⟨_, _, _⟩, rfl => rfl theorem Scalar.val_eq_of_eq {ty} {i j : Scalar ty} (h : Eq i j) : Eq i.val j.val := h ▸ rfl theorem Scalar.ne_of_val_ne {ty} {i j : Scalar ty} (h : Not (Eq i.val j.val)) : Not (Eq i j) := fun h' => absurd (val_eq_of_eq h') h instance (ty : ScalarTy) : DecidableEq (Scalar ty) := fun i j => match decEq i.val j.val with | isTrue h => isTrue (Scalar.eq_of_val_eq h) | isFalse h => isFalse (Scalar.ne_of_val_ne h) /- Remark: we can't write the following instance because of restrictions about the type class parameters (`ty` doesn't appear in the return type, which is forbidden): ``` instance Scalar.cast (ty : ScalarTy) : Coe (Scalar ty) Int where coe := λ v => v.val ``` -/ def Scalar.toInt {ty} (n : Scalar ty) : Int := n.val -- -- We now define a type class that subsumes the various machine integer types, so -- -- as to write a concise definition for scalar_cast, rather than exhaustively -- -- enumerating all of the possible pairs. We remark that Rust has sane semantics -- -- and fails if a cast operation would involve a truncation or modulo. -- class MachineInteger (t: Type) where -- size: Nat -- val: t -> Fin size -- ofNatCore: (n:Nat) -> LT.lt n size -> t -- set_option hygiene false in -- run_cmd -- for typeName in [`UInt8, `UInt16, `UInt32, `UInt64, `USize].map Lean.mkIdent do -- Lean.Elab.Command.elabCommand (← `( -- namespace $typeName -- instance: MachineInteger $typeName where -- size := size -- val := val -- ofNatCore := ofNatCore -- end $typeName -- )) -- -- Aeneas only instantiates the destination type (`src` is implicit). We rely on -- -- Lean to infer `src`. -- def scalar_cast { src: Type } (dst: Type) [ MachineInteger src ] [ MachineInteger dst ] (x: src): Result dst := -- if h: MachineInteger.val x < MachineInteger.size dst then -- .ret (MachineInteger.ofNatCore (MachineInteger.val x).val h) -- else -- .fail integerOverflow end Primitives