Add explicit boxing and unboxing instructions. Recall that the Lean to λ_pure compiler produces code without these instructions.

Assumptions:

• This transformation is applied before explicit RC instructions (inc, dec) are inserted.
• This transformation is applied before lower level optimizations are applied which use Expr.isShared, Expr.isTaggedPtr, and FnBody.set.

@[reducible, inline]

abbrev Lean.IR.ExplicitBoxing.N (α : Type) : Type

def Lean.IR.ExplicitBoxing.requiresBoxedVersion (env : Environment) (decl : Decl) : Bool

def Lean.IR.ExplicitBoxing.mkBoxedVersionAux (decl : Decl) : N Decl

def Lean.IR.ExplicitBoxing.mkBoxedVersion (decl : Decl) : Decl

def Lean.IR.ExplicitBoxing.addBoxedVersions (env : Environment) (decls : Array Decl) : Array Decl

def Lean.IR.ExplicitBoxing.eqvTypes (t₁ t₂ : IRType) : Bool

structure Lean.IR.ExplicitBoxing.BoxingContext : Type

• f : FunId
• localCtx : LocalContext
• resultType : IRType
• decls : Array Decl
• env : Environment

structure Lean.IR.ExplicitBoxing.BoxingState : Type

• nextIdx : Index
• auxDecls : Array Decl

  We create auxiliary declarations when boxing constant and literals. The idea is to avoid code such as

  let x1 := Uint64.inhabited;
  let x2 := box x1;
  ...
  

  We currently do not cache these declarations in an environment extension, but we use auxDeclCache to avoid creating equivalent auxiliary declarations more than once when processing the same IR declaration.

• auxDeclCache : AssocList FnBody Expr
• nextAuxId : Nat

@[reducible, inline]

abbrev Lean.IR.ExplicitBoxing.M (α : Type) : Type

def Lean.IR.ExplicitBoxing.getEnv : M Environment

def Lean.IR.ExplicitBoxing.getLocalContext : M LocalContext

def Lean.IR.ExplicitBoxing.getResultType : M IRType

def Lean.IR.ExplicitBoxing.getVarType (x : VarId) : M IRType

def Lean.IR.ExplicitBoxing.getJPParams (j : JoinPointId) : M (Array Param)

def Lean.IR.ExplicitBoxing.getDecl (fid : FunId) : M Decl

@[inline]

def Lean.IR.ExplicitBoxing.withParams {α : Type} (xs : Array Param) (k : M α) : M α

@[inline]

def Lean.IR.ExplicitBoxing.withVDecl {α : Type} (x : VarId) (ty : IRType) (v : Expr) (k : M α) : M α

@[inline]

def Lean.IR.ExplicitBoxing.withJDecl {α : Type} (j : JoinPointId) (xs : Array Param) (v : FnBody) (k : M α) : M α

def Lean.IR.ExplicitBoxing.mkCast (x : VarId) (xType expectedType : IRType) : M Expr

Auxiliary function used by castVarIfNeeded. It is used when the expected type does not match xType. If xType is scalar, then we need to "box" it. Otherwise, we need to "unbox" it.

@[inline]

def Lean.IR.ExplicitBoxing.castVarIfNeeded (x : VarId) (expected : IRType) (k : VarId → M FnBody) : M FnBody

@[inline]

def Lean.IR.ExplicitBoxing.castArgIfNeeded (x : Arg) (expected : IRType) (k : Arg → M FnBody) : M FnBody

def Lean.IR.ExplicitBoxing.castArgsIfNeededAux (xs : Array Arg) (typeFromIdx : Nat → IRType) : M (Array Arg × Array FnBody)

@[inline]

def Lean.IR.ExplicitBoxing.castArgsIfNeeded (xs : Array Arg) (ps : Array Param) (k : Array Arg → M FnBody) : M FnBody

@[inline]

def Lean.IR.ExplicitBoxing.boxArgsIfNeeded (xs : Array Arg) (k : Array Arg → M FnBody) : M FnBody

def Lean.IR.ExplicitBoxing.unboxResultIfNeeded (x : VarId) (ty : IRType) (e : Expr) (b : FnBody) : M FnBody

def Lean.IR.ExplicitBoxing.castResultIfNeeded (x : VarId) (ty : IRType) (e : Expr) (eType : IRType) (b : FnBody) : M FnBody

def Lean.IR.ExplicitBoxing.visitVDeclExpr (x : VarId) (ty : IRType) (e : Expr) (b : FnBody) : M FnBody

def Lean.IR.ExplicitBoxing.tryCorrectVDeclType (ty : IRType) (e : Expr) : M IRType

Up to this point the type system of IR is quite loose so we can for example encounter situations such as

let y : obj := f x

where f : obj -> uint8. It is the job of the boxing pass to enforce a stricter obj/scalar separation and as such it needs to correct situations like this.

partial def Lean.IR.ExplicitBoxing.visitFnBody : FnBody → M FnBody

def Lean.IR.ExplicitBoxing.run (env : Environment) (decls : Array Decl) : Array Decl

def Lean.IR.explicitBoxing (decls : Array Decl) : CompilerM (Array Decl)