/-
Copyright (c) 2019 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
prelude
import init.control.reader
import init.control.conditional
import init.lean.compiler.ir.basic

namespace Lean
namespace IR
namespace UniqueIds

abbrev M := StateT IndexSet Id

def checkId (id : Index) : M Bool :=
do found ← get;
   if found.contains id then pure false
   else modify (fun s => s.insert id) *> pure true

def checkParams (ps : Array Param) : M Bool :=
ps.allM $ fun p => checkId p.x.idx

partial def checkFnBody : FnBody → M Bool
| (FnBody.vdecl x _ _ b)  := checkId x.idx <&&> checkFnBody b
| (FnBody.jdecl j ys _ b) := checkId j.idx <&&> checkParams ys <&&> checkFnBody b
| (FnBody.case _ _ alts)  := alts.allM $ fun alt => checkFnBody alt.body
| b                       := if b.isTerminal then pure true else checkFnBody b.body

partial def checkDecl : Decl → M Bool
| (Decl.fdecl _ xs _ b)  := checkParams xs <&&> checkFnBody b
| (Decl.extern _ xs _ _) := checkParams xs

end UniqueIds

/- Return true if variable, parameter and join point ids are unique -/
def Decl.uniqueIds (d : Decl) : Bool :=
(UniqueIds.checkDecl d).run' {}

namespace NormalizeIds

abbrev M := ReaderT IndexRenaming Id

def normIndex (x : Index) : M Index :=
fun m => match m.find x with
| some y => y
| none   => x

def normVar (x : VarId) : M VarId :=
VarId.mk <$> normIndex x.idx

def normJP (x : JoinPointId) : M JoinPointId :=
JoinPointId.mk <$> normIndex x.idx

def normArg : Arg → M Arg
| (Arg.var x) := Arg.var <$> normVar x
| other       := pure other

def normArgs (as : Array Arg) : M (Array Arg) :=
fun m => as.map $ fun a => normArg a m

def normExpr : Expr → M Expr
| (Expr.ctor c ys)      m := Expr.ctor c (normArgs ys m)
| (Expr.reset n x)      m := Expr.reset n (normVar x m)
| (Expr.reuse x c u ys) m := Expr.reuse (normVar x m) c u (normArgs ys m)
| (Expr.proj i x)       m := Expr.proj i (normVar x m)
| (Expr.uproj i x)      m := Expr.uproj i (normVar x m)
| (Expr.sproj n o x)    m := Expr.sproj n o (normVar x m)
| (Expr.fap c ys)       m := Expr.fap c (normArgs ys m)
| (Expr.pap c ys)       m := Expr.pap c (normArgs ys m)
| (Expr.ap x ys)        m := Expr.ap (normVar x m) (normArgs ys m)
| (Expr.box t x)        m := Expr.box t (normVar x m)
| (Expr.unbox x)        m := Expr.unbox (normVar x m)
| (Expr.isShared x)     m := Expr.isShared (normVar x m)
| (Expr.isTaggedPtr x)  m := Expr.isTaggedPtr (normVar x m)
| e@(Expr.lit v)        m :=  e

abbrev N := ReaderT IndexRenaming (State Nat)

@[inline] def withVar {α : Type} (x : VarId) (k : VarId → N α) : N α :=
fun m => do
  n ← getModify (fun n => n + 1);
  k { idx := n } (m.insert x.idx n)

@[inline] def withJP {α : Type} (x : JoinPointId) (k : JoinPointId → N α) : N α :=
fun m => do
  n ← getModify (fun n => n + 1);
  k { idx := n } (m.insert x.idx n)

@[inline] def withParams {α : Type} (ps : Array Param) (k : Array Param → N α) : N α :=
fun m => do
  m ← ps.mfoldl (fun (m : IndexRenaming) p => do n ← getModify (fun n => n + 1); pure $ m.insert p.x.idx n) m;
  let ps := ps.map $ fun p => { x := normVar p.x m, .. p };
  k ps m

instance MtoN {α} : HasCoe (M α) (N α) :=
⟨fun x m => pure $ x m⟩

partial def normFnBody : FnBody → N FnBody
| (FnBody.vdecl x t v b)     := do v ← normExpr v; withVar x $ fun x => FnBody.vdecl x t v <$> normFnBody b
| (FnBody.jdecl j ys v b)    := do
  (ys, v) ← withParams ys $ fun ys => do { v ← normFnBody v; pure (ys, v) };
  withJP j $ fun j => FnBody.jdecl j ys v <$> normFnBody b
| (FnBody.set x i y b)       := do x ← normVar x; y ← normArg y; FnBody.set x i y <$> normFnBody b
| (FnBody.uset x i y b)      := do x ← normVar x; y ← normVar y; FnBody.uset x i y <$> normFnBody b
| (FnBody.sset x i o y t b)  := do x ← normVar x; y ← normVar y; FnBody.sset x i o y t <$> normFnBody b
| (FnBody.setTag x i b)      := do x ← normVar x; FnBody.setTag x i <$> normFnBody b
| (FnBody.inc x n c b)       := do x ← normVar x; FnBody.inc x n c <$> normFnBody b
| (FnBody.dec x n c b)       := do x ← normVar x; FnBody.dec x n c <$> normFnBody b
| (FnBody.del x b)           := do x ← normVar x; FnBody.del x <$> normFnBody b
| (FnBody.mdata d b)         := FnBody.mdata d <$> normFnBody b
| (FnBody.case tid x alts)   := do
  x ← normVar x;
  alts ← alts.mmap $ fun alt => alt.mmodifyBody normFnBody;
  pure $ FnBody.case tid x alts
| (FnBody.jmp j ys)         := FnBody.jmp <$> normJP j <*> normArgs ys
| (FnBody.ret x)            := FnBody.ret <$> normArg x
| FnBody.unreachable        := pure FnBody.unreachable

def normDecl : Decl → N Decl
| (Decl.fdecl f xs t b) := withParams xs $ fun xs => Decl.fdecl f xs t <$> normFnBody b
| other                 := pure other

end NormalizeIds

/- Create a declaration equivalent to `d` s.t. `d.normalizeIds.uniqueIds == true` -/
def Decl.normalizeIds (d : Decl) : Decl :=
(NormalizeIds.normDecl d {}).run' 1

/- Apply a function `f : VarId → VarId` to variable occurrences.
   The following functions assume the IR code does not have variable shadowing. -/
namespace MapVars

@[inline] def mapArg (f : VarId → VarId) : Arg → Arg
| (Arg.var x) := Arg.var (f x)
| a           := a

@[specialize] def mapArgs (f : VarId → VarId) (as : Array Arg) : Array Arg :=
as.map (mapArg f)

@[specialize] def mapExpr (f : VarId → VarId) : Expr → Expr
| (Expr.ctor c ys)      := Expr.ctor c (mapArgs f ys)
| (Expr.reset n x)      := Expr.reset n (f x)
| (Expr.reuse x c u ys) := Expr.reuse (f x) c u (mapArgs f ys)
| (Expr.proj i x)       := Expr.proj i (f x)
| (Expr.uproj i x)      := Expr.uproj i (f x)
| (Expr.sproj n o x)    := Expr.sproj n o (f x)
| (Expr.fap c ys)       := Expr.fap c (mapArgs f ys)
| (Expr.pap c ys)       := Expr.pap c (mapArgs f ys)
| (Expr.ap x ys)        := Expr.ap (f x) (mapArgs f ys)
| (Expr.box t x)        := Expr.box t (f x)
| (Expr.unbox x)        := Expr.unbox (f x)
| (Expr.isShared x)     := Expr.isShared (f x)
| (Expr.isTaggedPtr x)  := Expr.isTaggedPtr (f x)
| e@(Expr.lit v)        :=  e

@[specialize] partial def mapFnBody (f : VarId → VarId) : FnBody → FnBody
| (FnBody.vdecl x t v b)     := FnBody.vdecl x t (mapExpr f v) (mapFnBody b)
| (FnBody.jdecl j ys v b)    := FnBody.jdecl j ys (mapFnBody v) (mapFnBody b)
| (FnBody.set x i y b)       := FnBody.set (f x) i (mapArg f y) (mapFnBody b)
| (FnBody.setTag x i b)      := FnBody.setTag (f x) i (mapFnBody b)
| (FnBody.uset x i y b)      := FnBody.uset (f x) i (f y) (mapFnBody b)
| (FnBody.sset x i o y t b)  := FnBody.sset (f x) i o (f y) t (mapFnBody b)
| (FnBody.inc x n c b)       := FnBody.inc (f x) n c (mapFnBody b)
| (FnBody.dec x n c b)       := FnBody.dec (f x) n c (mapFnBody b)
| (FnBody.del x b)           := FnBody.del (f x) (mapFnBody b)
| (FnBody.mdata d b)         := FnBody.mdata d (mapFnBody b)
| (FnBody.case tid x alts)   := FnBody.case tid (f x) (alts.map (fun alt => alt.modifyBody mapFnBody))
| (FnBody.jmp j ys)          := FnBody.jmp j (mapArgs f ys)
| (FnBody.ret x)             := FnBody.ret (mapArg f x)
| FnBody.unreachable         := FnBody.unreachable

end MapVars

@[inline] def FnBody.mapVars (f : VarId → VarId) (b : FnBody) : FnBody :=
MapVars.mapFnBody f b

/- Replace `x` with `y` in `b`. This function assumes `b` does not shadow `x` -/
def FnBody.replaceVar (x y : VarId) (b : FnBody) : FnBody :=
b.mapVars $ fun z => if x == z then y else z

end IR
end Lean
