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 FnBody.case has been simplified and Alt.default is used. Reason: if there is no Alt.default branch, then we can decide whether x at FnBody.case x alts is an enumeration type by simply inspecting the CtorInfo values at alts.
• This transformation is applied before lower level optimizations are applied which use Expr.isShared, Expr.isTaggedPtr, and FnBody.set.
• This transformation is applied after reset and reuse instructions have been added. Reason: resetreuse.lean ignores box and unbox instructions.

def Lean.IR.ExplicitBoxing.mkBoxedName (n : Name) : Name

def Lean.IR.ExplicitBoxing.isBoxedName (name : Name) : Bool

@[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.getScrutineeType (alts : Array Alt) : IRType

Infer scrutinee type using case alternatives. This can be done whenever alts does not contain an Alt.default _ value.

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

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)