/- Copyright (c) 2019 Microsoft Corporation. All rights reserved. Released under Apache 2.0 license as described in the file LICENSE. Authors: Leonardo de Moura -/ import init.lean.name init.lean.kvmap prelude /- Implements (extended) λ_pure and λ_RC proposed in the article "Counting Immutable Beans", Sebastian Ullrich and Leonardo de Moura. The Lean to IR transformation produces λ_pure code. That is, then transformed using the procedures described in the paper above. -/ namespace lean namespace ir /- Variable identifier -/ abbreviation varid := name /- Function identifier -/ abbreviation fid := name /- Join point identifier -/ abbreviation jpid := name /- Low level IR types. Most are self explanatory. - `usize` represents the C++ `size_t` type. We have it here because it is 32-bit in 32-bit machines, and 64-bit in 64-bit machines, and we want the C++ backend for our compiler to generate platform independent code. - `irrelevant` for Lean types, propositions and proofs. - `object` a pointer to a value in the heap. - `tobject` a pointer to a value in the heap or tagged pointer (i.e., the least significant bit is 1) storing a scalar value. Remark: the RC operations for `tobject` are slightly more expensive because we first need to test whether the `tobject` is really a pointer or not. Remark: the Lean runtime assumes that sizeof(void*) == sizeof(size_t). Lean cannot be compiled on old platforms where this is not true. -/ inductive type | float | uint8 | uint16 | uint32 | uint64 | usize | irrelevant | object | tobject def type.beq : type → type → bool | type.float type.float := tt | type.uint8 type.uint8 := tt | type.uint16 type.uint16 := tt | type.uint32 type.uint32 := tt | type.uint64 type.uint64 := tt | type.usize type.usize := tt | type.irrelevant type.irrelevant := tt | type.object type.object := tt | type.tobject type.tobject := tt | _ _ := ff instance type.has_beq : has_beq type := ⟨type.beq⟩ /- Arguments to applications, constructors, etc. We use `irrelevant` for Lean types, propositions and proofs that have been erased. Recall that for a function `f`, we also generate `f._rarg` which does not take `irrelevant` arguments. However, `f._rarg` is only safe to be used in full applications. -/ inductive arg | var (id : varid) | irrelevant inductive litval | num (v : nat) | str (v : string) def litval.beq : litval → litval → bool | (litval.num v₁) (litval.num v₂) := v₁ = v₂ | (litval.str v₁) (litval.str v₂) := v₁ = v₂ | _ _ := ff instance litval.has_beq : has_beq litval := ⟨litval.beq⟩ /- Constructor information. - `id` is the name of the constructor in Lean. - `cidx` is the constructor index (aka tag). - `usize` is the number of arguments of type `usize`. - `ssize` is the number of bytes used to store scalar values. Recall that a constructor object contains a header, then a sequence of pointers to other Lean objects, a sequence of `usize` (i.e., `size_t`) scalar values, and a sequence of other scalar values. -/ structure ctor_info := (id : name) (cidx : nat) (usize : nat) (ssize : nat) def ctor_info.beq : ctor_info → ctor_info → bool | ⟨id₁, cidx₁, usize₁, ssize₁⟩ ⟨id₂, cidx₂, usize₂, ssize₂⟩ := id₁ = id₂ && cidx₁ = cidx₂ && usize₁ = usize₂ && ssize₁ = ssize₂ instance ctor_info.has_beq : has_beq ctor_info := ⟨ctor_info.beq⟩ inductive expr | ctor (i : ctor_info) (ys : list arg) | reset (x : varid) /- `reuse x in ctor_i ys` instruction in the paper. -/ | reuse (x : varid) (i : ctor_info) (ys : list arg) /- Extract the `tobject` value at position `sizeof(void)*i` from `x`. -/ | proj (i : nat) (x : varid) /- Extract the `usize` value at position `sizeof(void)*i` from `x`. -/ | uproj (i : nat) (x : varid) /- Extract the scalar value at position `n` (in bytes) from `x`. -/ | sproj (n : nat) (x : varid) /- Full application. -/ | fap (c : fid) (ys : list arg) /- Partial application that creates a `pap` value (aka closure in our nonstandard terminology). -/ | pap (c : fid) (ys : list arg) /- Application. `x` must be a `pap` value. -/ | ap (x : varid) (ys : list arg) /- Given `x : ty` where `ty` is a scalar type, this operation returns a value of type `tobject`. For small scalar values, the result is a tagged pointer, and no memory allocation is performed. -/ | box (ty : type) (x : varid) /- Given `x : [t]object`, obtain the scalar value. -/ | unbox (x : varid) | lit (v : litval) /- Return `1 : uint8` iff `RC(x) > 1` -/ | is_shared (x : varid) /- Return `1 : uint8` iff `x : tobject` is a tagged pointer (storing a scalar value). -/ | is_tagged_ptr (x : varid) structure param := (x : name) (borrowed : bool) (ty : type) inductive alt (fnbody : Type) : Type | ctor (info : ctor_info) (b : fnbody) : alt | default (b : fnbody) : alt inductive fnbody /- `let x : ty := e; b` -/ | vdecl (x : varid) (ty : type) (e : expr) (b : fnbody) /- Join point declaration `let j (xs) : ty := e; b` -/ | jdecl (j : jpid) (xs : list param) (ty : type) (e : expr) (b : fnbody) /- Store `y` at position `sizeof(void*)*i` in `x`. `x` must be a constructor object and `RC(x)` must be 1. This operation is not part of λ_pure is only used during optimization. -/ | set (x : varid) (i : nat) (y : varid) (b : fnbody) /- Store `y : usize` at position `sizeof(void*)*i` in `x`. `x` must be a constructor object and `RC(x)` must be 1. -/ | uset (x : varid) (i : nat) (y : varid) (b : fnbody) /- Store `y : ty` at position `sizeof(void*)*i + offset` in `x`. `x` must be a constructor object and `RC(x)` must be 1. `ty` must not be `object`, `tobject`, `irrelevant` nor `usize`. -/ | sset (x : varid) (i : nat) (offset : nat) (y : varid) (ty : type) (b : fnbody) | release (x : varid) (i : nat) (b : fnbody) /- RC increment for `object` -/ | inc (x : varid) (n : nat) (b : fnbody) /- RC decrement for `object` -/ | dec (x : varid) (n : nat) (b : fnbody) /- RC increment for `tobject` -/ | tinc (x : varid) (n : nat) (b : fnbody) /- RC decrement for `tobject` -/ | tdec (x : varid) (n : nat) (b : fnbody) | mdata (d : kvmap) (b : fnbody) | case (tid : name) (cs : list (alt fnbody)) | ret (x : varid) /- Jump to join point `j` -/ | jmp (j : jpid) (ys : list arg) | unreachable inductive decl | fdecl (f : fid) (xs : list param) (ty : type) (b : fnbody) | extern (f : fid) (xs : list param) (ty : type) /-- `expr.is_pure e` return `tt` iff `e` is in the `λ_pure` fragment. -/ def expr.is_pure : expr → bool | (expr.ctor _ _) := tt | (expr.proj _ _) := tt | (expr.uproj _ _) := tt | (expr.sproj _ _) := tt | (expr.fap _ _) := tt | (expr.pap _ _) := tt | (expr.ap _ _) := tt | (expr.lit _) := tt | _ := ff /-- `fnbody.is_pure b` return `tt` iff `b` is in the `λ_pure` fragment. -/ mutual def fnbody.is_pure, alts.is_pure, alt.is_pure with fnbody.is_pure : fnbody → bool | (fnbody.vdecl _ _ e b) := e.is_pure && b.is_pure | (fnbody.jdecl _ _ _ e b) := e.is_pure && b.is_pure | (fnbody.uset _ _ _ b) := b.is_pure | (fnbody.sset _ _ _ _ _ b) := b.is_pure | (fnbody.mdata _ b) := b.is_pure | (fnbody.case _ cs) := alts.is_pure cs | (fnbody.ret _) := tt | (fnbody.jmp _ _) := tt | fnbody.unreachable := tt | _ := ff with alts.is_pure : list (alt fnbody) → bool | [] := tt | (a::as) := a.is_pure && alts.is_pure as with alt.is_pure : alt fnbody → bool | (alt.ctor _ b) := b.is_pure | (alt.default b) := ff class has_alpha_eqv (α : Type) := (aeqv : name_map name → α → α → bool) local notation a `=[`:50 ρ `]=`:0 b:50 := has_alpha_eqv.aeqv ρ a b def varid.alpha_eqv (ρ : name_map name) (v₁ v₂ : varid) : bool := v₁ = v₂ || ρ.find v₁ = v₂ instance varid.has_aeqv : has_alpha_eqv varid := ⟨varid.alpha_eqv⟩ def arg.alpha_eqv (ρ : name_map name) : arg → arg → bool | (arg.var v₁) (arg.var v₂) := v₁ =[ρ]= v₂ | arg.irrelevant arg.irrelevant := tt | _ _ := ff instance arg.has_aeqv : has_alpha_eqv arg := ⟨arg.alpha_eqv⟩ def args.alpha_eqv (ρ : name_map name) : list arg → list arg → bool | [] [] := tt | (a::as) (b::bs) := a =[ρ]= b && args.alpha_eqv as bs | _ _ := ff instance args.has_aeqv : has_alpha_eqv (list arg) := ⟨args.alpha_eqv⟩ def expr.alpha_eqv (ρ : name_map name) : expr → expr → bool | (expr.ctor i₁ ys₁) (expr.ctor i₂ ys₂) := i₁ == i₂ && ys₁ =[ρ]= ys₂ | (expr.reset x₁) (expr.reset x₂) := x₁ =[ρ]= x₂ | (expr.reuse x₁ i₁ ys₁) (expr.reuse x₂ i₂ ys₂) := x₁ =[ρ]= x₂ && i₁ == i₂ && ys₁ =[ρ]= ys₂ | (expr.proj i₁ x₁) (expr.proj i₂ x₂) := i₁ = i₂ && x₁ =[ρ]= x₂ | (expr.uproj i₁ x₁) (expr.uproj i₂ x₂) := i₁ = i₂ && x₁ =[ρ]= x₂ | (expr.sproj n₁ x₁) (expr.sproj n₂ x₂) := n₁ = n₂ && x₁ =[ρ]= x₂ | (expr.fap c₁ ys₁) (expr.fap c₂ ys₂) := c₁ = c₂ && ys₁ =[ρ]= ys₂ | (expr.pap c₁ ys₁) (expr.pap c₂ ys₂) := c₁ = c₂ && ys₂ =[ρ]= ys₂ | (expr.ap x₁ ys₁) (expr.ap x₂ ys₂) := x₁ =[ρ]= x₂ && ys₁ =[ρ]= ys₂ | (expr.box ty₁ x₁) (expr.box ty₂ x₂) := ty₁ == ty₂ && x₁ =[ρ]= x₂ | (expr.unbox x₁) (expr.unbox x₂) := x₁ =[ρ]= x₂ | (expr.lit v₁) (expr.lit v₂) := v₁ == v₂ | (expr.is_shared x₁) (expr.is_shared x₂) := x₁ =[ρ]= x₂ | (expr.is_tagged_ptr x₁) (expr.is_tagged_ptr x₂) := x₁ =[ρ]= x₂ | _ _ := ff end ir end lean