(* tree-to-cuda.sml
 *
 * COPYRIGHT (c) 2011 The Diderot Project (http://diderot-language.cs.uchicago.edu)
 * All rights reserved.
 *
 * Translate TreeIL to the CUDA version of CLang.
 *)

structure TreeToCUDA : sig

    datatype var = V of (CLang.ty * CLang.var)

    type env = var TreeIL.Var.Map.map

    val trType : TreeIL.Ty.ty -> CLang.ty

    val trBlock : env * TreeIL.block -> CLang.stm

    val trFragment : env * TreeIL.block -> env * CLang.stm list

    val trAssign : env * TreeIL.var * TreeIL.exp -> CLang.stm list

    val trExp : env * TreeIL.exp -> CLang.exp

  (* vector indexing support.  Arguments are: vector, index *)
    val vecIndex : CLang.exp * int -> CLang.exp

  end = struct

    structure CL = CLang
    structure RN = RuntimeNames
    structure IL = TreeIL
    structure Op = IL.Op
    structure Ty = IL.Ty
    structure V = IL.Var

    datatype var = datatype CLang.typed_var

    type env = var TreeIL.Var.Map.map

    fun lookup (env, x) = (case V.Map.find (env, x)
       of SOME(V(_, x')) => x'
        | NONE => raise Fail(concat["lookup(_, ", V.name x, ")"])
      (* end case *))

  (* integer literal expression *)
    fun intExp (i : int) = CL.mkInt(IntInf.fromInt i)

  (* the type of an image-data pointer. *)
    fun imageDataPtrTy rTy = CL.T_Qual("__global", CL.T_Ptr(CL.T_Num rTy))

  (* translate TreeIL types to CLang types *)
    fun trType ty = (case ty
           of Ty.BoolTy => CLang.T_Named "uint"
            | Ty.StringTy => CL.charPtr
            | Ty.IntTy => !RN.gIntTy
            | Ty.TensorTy[] => !RN.gRealTy
            | Ty.TensorTy[n] => CL.T_Named(RN.vecTy n)
            | Ty.TensorTy[n, m] => CL.T_Named(RN.matTy(n,m))
            | Ty.SeqTy(Ty.IntTy, n) => CL.T_Named(RN.ivecTy n)
            | Ty.SeqTy(Ty.TensorTy[] , n) => CL.T_Named(RN.vecTy n)
            | Ty.AddrTy(ImageInfo.ImgInfo{ty=(_, rTy), ...}) => imageDataPtrTy rTy
            | Ty.ImageTy(ImageInfo.ImgInfo{dim, ...}) => CL.T_Named(RN.imageTy dim)
            | _ => raise Fail(concat["TreeToC.trType(", Ty.toString ty, ")"])
          (* end case *))

  (* generate new variables *)
    local
      val count = ref 0
      fun freshName prefix = let
            val n = !count
            in
              count := n+1;
              concat[prefix, "_", Int.toString n]
            end
    in
    fun tmpVar ty = freshName "tmp"
    fun freshVar prefix = freshName prefix
    end (* local *)

  (* translate IL basis functions *)
    fun trApply (f, args) = CL.mkApply(ILBasis.toString f, args)

  (* vector indexing support.  Arguments are: vector, index *)
    local
      val fields = Vector.fromList [
              "s0", "s1", "s2", "s3",
              "s4", "s5", "s6", "s7",
              "s8", "s9", "sa", "sb",
              "sc", "sd", "se", "sf"
            ]
    in
    fun vecIndex (v, ix) = CL.mkSelect(v, Vector.sub(fields, ix))
    end

  (* translate a variable use *)
    fun trVar (env, x) = (case V.kind x
           of IL.VK_Global => CL.mkIndirect(CL.E_Var RN.globalsVarName, lookup(env, x))
            | IL.VK_Local => CL.mkVar(lookup(env, x))
          (* end case *))

  (* translate a state-variable use *)
    fun trStateVar (IL.SV{name, ...}) = CL.mkIndirect(CL.mkVar "selfIn", name)

    fun castArgs ty = List.map (fn e => CL.mkCast(ty, e))

  (* Translate a TreeIL operator application to a CLang expression *)
    fun trOp (rator, args) = (case (rator, args)
           of (Op.Add ty, [a, b]) => CL.mkBinOp(a, CL.#+, b)
            | (Op.Sub ty, [a, b]) => CL.mkBinOp(a, CL.#-, b)
            | (Op.Mul ty, [a, b]) => CL.mkBinOp(a, CL.#*, b)
            | (Op.Div ty, [a, b]) => CL.mkBinOp(a, CL.#/, b)
            | (Op.Neg ty, [a]) => CL.mkUnOp(CL.%-, a)
            | (Op.Abs(Ty.IntTy), args) => CL.mkApply("abs", args)
            | (Op.Abs(Ty.TensorTy[]), args) => CL.mkApply(RN.fabs, args)
            | (Op.Abs(Ty.TensorTy[_]), args) => CL.mkApply(RN.fabs, args)
            | (Op.Abs ty, [a]) => raise Fail(concat["Abs<", Ty.toString ty, ">"])
            | (Op.LT ty, [a, b]) => CL.mkBinOp(a, CL.#<, b)
            | (Op.LTE ty, [a, b]) => CL.mkBinOp(a, CL.#<=, b)
            | (Op.EQ ty, [a, b]) => CL.mkBinOp(a, CL.#==, b)
            | (Op.NEQ ty, [a, b]) => CL.mkBinOp(a, CL.#!=, b)
            | (Op.GTE ty, [a, b]) => CL.mkBinOp(a, CL.#>=, b)
            | (Op.GT ty, [a, b]) => CL.mkBinOp(a, CL.#>, b)
            | (Op.Not, [a]) => CL.mkUnOp(CL.%!, a)
            | (Op.Max, args) => CL.mkApply(RN.max, castArgs (!RN.gRealTy) args)
            | (Op.Min, args) => CL.mkApply(RN.min, castArgs (!RN.gRealTy) args)
            | (Op.Clamp ty, [lo, hi, x]) => CL.mkApply(RN.clamp, [x, lo, hi])
            | (Op.Lerp ty, args) => (case ty
                 of Ty.TensorTy[] => CL.mkApply(RN.lerp, castArgs (!RN.gRealTy) args)
                  | Ty.TensorTy[n] => CL.mkApply(RN.lerp, castArgs (CL.T_Named(RN.vecTy n)) args)
                  | _ => raise Fail(concat[
                    "lerp<", Ty.toString ty, "> not supported"
                      ])
                (* end case *))
            | (Op.Dot d, args) => CL.E_Apply(RN.dot, args)
            | (Op.MulVecMat(m, n), args) =>
                if (1 < m) andalso (m < 4) andalso (m = n)
                  then CL.E_Apply(RN.mulVecMat(m,n), args)
                  else raise Fail "unsupported vector-matrix multiply"
            | (Op.MulMatVec(m, n), args) =>
                if (1 < m) andalso (m < 4) andalso (m = n)
                  then CL.E_Apply(RN.mulMatVec(m,n), args)
                  else raise Fail "unsupported matrix-vector multiply"
            | (Op.MulMatMat(m, n, p), args) =>
                if (1 < m) andalso (m < 4) andalso (m = n) andalso (n = p)
                  then CL.E_Apply(RN.mulMatMat(m,n,p), args)
                  else raise Fail "unsupported matrix-matrix multiply"
            | (Op.Cross, args) => CL.E_Apply(RN.cross, args)
            | (Op.Norm(Ty.TensorTy[n]), args) => CL.E_Apply(RN.length, args)
            | (Op.Norm(Ty.TensorTy[m,n]), args) => CL.E_Apply(RN.norm(m,n), args)
            | (Op.Normalize d, args) => CL.E_Apply(RN.normalize, args)
            | (Op.Scale(Ty.TensorTy[n]), [s, v]) => CL.mkBinOp(s, CL.#*, v)
            | (Op.PrincipleEvec ty, _) => raise Fail "PrincipleEvec unimplemented"
            | (Op.Select(Ty.TupleTy tys, i), [a]) => raise Fail "Select unimplemented"
            | (Op.Index(Ty.SeqTy(Ty.IntTy, n), i), [a]) => vecIndex (a, i)
            | (Op.Index(Ty.TensorTy[n], i), [a]) => vecIndex (a, i)
            | (Op.Subscript(Ty.SeqTy(Ty.IntTy, n)), [v, CL.E_Int(ix, _)]) => vecIndex (v, Int.fromLarge ix)
            | (Op.Subscript(Ty.SeqTy(Ty.IntTy, n)), [v, ix]) => let
                val unionTy = CL.T_Named(concat["union", Int.toString n, !RN.gIntSuffix, "_t"])
                val vecExp = CL.mkSelect(CL.mkCast(unionTy, v), "i")
                in
                  CL.mkSubscript(vecExp, ix)
                end
            | (Op.Subscript(Ty.TensorTy[n]), [v, CL.E_Int(ix, _)]) => vecIndex (v, Int.fromLarge ix)
            | (Op.Subscript(Ty.TensorTy[n]), [v, ix]) => let
                val unionTy = CL.T_Named(concat["union", Int.toString n, !RN.gRealSuffix, "_t"])
                val vecExp = CL.mkSelect(CL.mkCast(unionTy, v), "r")
                in
                  CL.mkSubscript(vecExp, ix)
                end
            | (Op.Subscript(Ty.TensorTy[_,_]), [m, ix, CL.E_Int(jx, _)]) =>
                vecIndex(CL.mkSubscript(m, ix), Int.fromLarge jx)
            | (Op.Subscript(Ty.TensorTy[_,n]), [m, ix, jx]) => let
                val unionTy = CL.T_Named(concat["union", Int.toString n, !RN.gRealSuffix, "_t"])
                val vecExp = CL.mkSelect(CL.mkCast(unionTy, CL.mkSubscript(m, ix)), "r")
                in
                  CL.mkSubscript(vecExp, jx)
                end
            | (Op.Subscript ty, t::(ixs as _::_)) =>
                raise Fail(concat["Subscript<", Ty.toString ty, "> unsupported"])
            | (Op.Ceiling d, args) => CL.mkApply("ceil", args)
            | (Op.Floor d, args) => CL.mkApply("floor", args)
            | (Op.Round d, args) => CL.mkApply("round", args)
            | (Op.Trunc d, args) => CL.mkApply("trunc", args)
            | (Op.IntToReal, [a]) => CL.mkCast(!RN.gRealTy, a)
            | (Op.RealToInt 1, [a]) => CL.mkCast(!RN.gIntTy, a)
            | (Op.RealToInt d, args) => CL.mkApply(RN.vecftoi d, args)
(* FIXME: need type info *)
            | (Op.ImageAddress(ImageInfo.ImgInfo{ty=(_,rTy), ...}), [a as CL.E_Indirect(_,field)]) => let
                val cTy = imageDataPtrTy rTy
                in
                  CL.mkCast(cTy,
                    CL.mkSelect(CL.mkVar RN.globalImageDataName, RN.imageDataName field))
                end
            | (Op.LoadVoxels(info, 1), [a]) => let
                val realTy as CL.T_Num rTy = !RN.gRealTy
                val a = CL.E_UnOp(CL.%*, a)
                in
                  if (rTy = ImageInfo.sampleTy info)
                    then a
                    else CL.E_Cast(realTy, a)
                end
            | (Op.LoadVoxels _, [a]) =>
                raise Fail("impossible " ^ Op.toString rator)
            | (Op.PosToImgSpace(ImageInfo.ImgInfo{dim, ...}), [img, pos]) =>
                CL.mkApply(RN.toImageSpace dim, [CL.mkUnOp(CL.%&,img), pos])
            | (Op.TensorToWorldSpace(info, ty), [v, x]) =>
                CL.mkApply(RN.toWorldSpace ty, [CL.mkUnOp(CL.%&,v), x])
            | (Op.LoadImage info, [a]) =>
                raise Fail("impossible " ^ Op.toString rator)
            | (Op.Inside(ImageInfo.ImgInfo{dim, ...}, s), [pos, img]) =>
                CL.mkApply(RN.inside dim, [pos, CL.mkUnOp(CL.%&,img), intExp s])
            | (Op.Input(ty, name, desc), []) =>
                raise Fail("impossible " ^ Op.toString rator)
            | (Op.InputWithDefault(ty, name, desc), [a]) =>
                raise Fail("impossible " ^ Op.toString rator)
            | _ => raise Fail(concat[
              "unknown or incorrect operator ", Op.toString rator
            ])
          (* end case *))

    fun trExp (env, e) = (case e
           of IL.E_State x => trStateVar x
            | IL.E_Var x => trVar (env, x)
            | IL.E_Lit(Literal.Int n) => CL.mkIntTy(n, !RN.gIntTy)
            | IL.E_Lit(Literal.Bool b) => CL.mkBool b
            | IL.E_Lit(Literal.Float f) => CL.mkFlt(f, !RN.gRealTy)
            | IL.E_Lit(Literal.String s) => CL.mkStr s
            | IL.E_Op(rator, args) => trOp (rator, trExps(env, args))
            | IL.E_Apply(f, args) => trApply(f, trExps(env, args))
            | IL.E_Cons(Ty.TensorTy[n], args) => CL.mkApply(RN.mkVec n, trExps(env, args))
            | IL.E_Cons(ty, _) => raise Fail(concat["E_Cons(", Ty.toString ty, ", _) in expression"])
          (* end case *))

    and trExps (env, exps) = List.map (fn exp => trExp(env, exp)) exps
   
    fun trLHSVar (env, lhs) = (case V.kind lhs
           of IL.VK_Global => CL.mkIndirect(CL.mkVar RN.globalsVarName, lookup(env, lhs))
            | IL.VK_Local => CL.mkVar(lookup(env, lhs))
          (* end case *))

    fun trLHSStateVar (IL.SV{name, ...}) = CL.mkIndirect(CL.mkVar "selfOut", name)

    fun trSet (env, lhs, rhs) = (
        (* certain rhs forms, such as those that return a matrix,
         * require a function call instead of an assignment
         *)
          case rhs
           of IL.E_Op(Op.Add(Ty.TensorTy[m,n]), args) =>
                [CL.mkCall(RN.addMat(m,n),  lhs :: trExps(env, args))]
            | IL.E_Op(Op.Sub(Ty.TensorTy[m,n]), args) =>
                [CL.mkCall(RN.subMat(m,n),  lhs :: trExps(env, args))]
            | IL.E_Op(Op.Neg(Ty.TensorTy[m,n]), args) =>
                [CL.mkCall(RN.scaleMat(m,n),  lhs :: intExp ~1 :: trExps(env, args))]
            | IL.E_Op(Op.Scale(Ty.TensorTy[m,n]), args) =>
                [CL.mkCall(RN.scaleMat(m,n),  lhs :: trExps(env, args))]
            | IL.E_Op(Op.MulMatMat(m,n,p), args) =>
                [CL.mkCall(RN.mulMatMat(m,n,p), lhs :: trExps(env, args))]
            | IL.E_Op(Op.Identity n, args) =>
                [CL.mkCall(RN.identityMat n, [lhs])]
            | IL.E_Op(Op.Zero(Ty.TensorTy[m,n]), args) =>
                [CL.mkCall(RN.zeroMat(m,n), [lhs])]
            | IL.E_Op(Op.TensorToWorldSpace(info, ty as Ty.TensorTy[_,_]), [img,src]) =>
                [CL.mkCall(RN.toWorldSpace ty, lhs :: [CL.mkUnOp(CL.%&,trExp(env, img)),trExp(env, src)] )]
            | IL.E_Op(Op.LoadVoxels(info, n), [a]) =>
                if (n > 1)
                  then let
                    val stride = ImageInfo.stride info
                    val rTy = ImageInfo.sampleTy info
                    val vp = freshVar "vp"
                    val needsCast = (CL.T_Num rTy <> !RN.gRealTy)
                    fun mkLoad i = let
                          val e = CL.mkSubscript(CL.mkVar vp, intExp(i*stride))
                          in
                            if needsCast then CL.mkCast(!RN.gRealTy, e) else e
                          end
                    in [
                      CL.mkDecl(imageDataPtrTy rTy, vp, SOME(CL.I_Exp(trExp(env, a)))),
                      CL.mkAssign(lhs,
                      CL.mkApply(RN.mkVec n, List.tabulate (n, mkLoad)))
                    ] end
                else [CL.mkAssign(lhs, trExp(env, rhs))]
            | IL.E_Cons(Ty.TensorTy[n,m], args) => let
              (* matrices are represented as arrays of union<d><ty>_t vectors *)
                fun doRows (_, []) = []
                  | doRows (i, e::es) =
                      CL.mkAssign(CL.mkSubscript(lhs, intExp i), e)
                        :: doRows (i+1, es)
                in
                  doRows (0, trExps(env, args))
                end
            | IL.E_Var x => (case IL.Var.ty x
                 of Ty.TensorTy[n,m] => [CL.mkCall(RN.copyMat(n,m), [lhs, trVar(env, x)])]
                  | _ => [CL.mkAssign(lhs, trVar(env, x))]
                (* end case *))
            | _ => [CL.mkAssign(lhs, trExp(env, rhs))]
          (* end case *))

    fun trAssign (env, lhs, rhs) = trSet (env, trLHSVar (env, lhs), rhs)

    fun trLocals (env : env, locals) = 
          List.foldl
            (fn (x, env) => V.Map.insert(env, x, V(trType(V.ty x), V.name x)))
              env locals

  (* generate code to check the status of runtime-system calls *)
    fun checkSts mkDecl = let
          val sts = freshVar "sts"
          in
            mkDecl sts @
            [CL.mkIfThen(
              CL.mkBinOp(CL.mkVar "DIDEROT_OK", CL.#!=, CL.mkVar sts),
              CL.mkCall("exit", [intExp 1]))]
          end

    fun trStms (env, stms) = let
          fun trStmt (env, stm) = (case stm
             of IL.S_Comment text => [CL.mkComment text]
              | IL.S_Assign([x], exp) => trAssign (env, x, exp)
              | IL.S_IfThen(cond, thenBlk) =>
                  [CL.mkIfThen(trExp(env, cond), trBlk(env, thenBlk))]
              | IL.S_IfThenElse(cond, thenBlk, elseBlk) =>
                  [CL.mkIfThenElse(trExp(env, cond),
                    trBlk(env, thenBlk),
                    trBlk(env, elseBlk))]
              | IL.S_New _ => raise Fail "new not supported yet" (* FIXME *)
              | IL.S_Save([x], exp) => trSet (env, trLHSStateVar x, exp)
(* FIXME: I think that S_LoadImage should never happen in OpenCL code [jhr] *)
              | IL.S_LoadImage(lhs, dim, name) => checkSts (fn sts => let
                  val lhs = lookup(env, lhs)
                  val name = trExp(env, name)
                  val imgTy = CL.T_Named(RN.imageTy dim)
                  val loadFn = RN.loadImage dim
                  in [
                    CL.mkDecl(
                      CL.T_Named RN.statusTy, sts,
                      SOME(CL.I_Exp(CL.E_Apply(loadFn, [name, CL.mkUnOp(CL.%&, CL.E_Var lhs)]))))
                  ] end)
(* FIXME: I think that S_Input should never happen in OpenCL code [jhr] *)
              | IL.S_Input(lhs, name, desc, optDflt) => checkSts (fn sts => let
                  val inputFn = RN.input(V.ty lhs)
                  val lhs = lookup(env, lhs)
                  val (initCode, hasDflt) = (case optDflt
                     of SOME e => ([CL.mkAssign(CL.E_Var lhs, trExp(env, e))], true)
                      | NONE => ([], false)
                    (* end case *))
                  val code = [
                      CL.mkDecl(
                        CL.T_Named RN.statusTy, sts,
                        SOME(CL.I_Exp(CL.E_Apply(inputFn, [
                        CL.E_Str name, CL.mkUnOp(CL.%&, CL.mkIndirect(CL.mkVar (RN.globalsVarName), lhs)), CL.mkBool hasDflt
                      ]))))
                    ]
                  in
                    initCode @ code
                  end)
              | IL.S_Exit args => [CL.mkReturn NONE]
              | IL.S_Active => [CL.mkReturn(SOME(CL.mkVar RN.kActive))]
              | IL.S_Stabilize => [CL.mkReturn(SOME(CL.mkVar RN.kStabilize))]
              | IL.S_Die => [CL.mkReturn(SOME(CL.mkVar RN.kDie))]
            (* end case *))
          in
            List.foldr (fn (stm, stms) => trStmt(env, stm)@stms) [] stms
          end

    and trBlk (env, IL.Block{locals, body}) = let
          val env = trLocals (env, locals)
          val stms = trStms (env, body)
          fun mkDecl (x, stms) = (case V.Map.find (env, x)
                 of SOME(V(ty, x')) => CL.mkDecl(ty, x', NONE) :: stms
                  | NONE => raise Fail(concat["mkDecl(", V.name x, ", _)"])
                (* end case *))
          val stms = List.foldr mkDecl stms locals
          in
            CL.mkBlock stms
          end

    fun trFragment (env, IL.Block{locals, body}) = let
          val env = trLocals (env, locals)
          val stms = trStms (env, body)
          fun mkDecl (x, stms) = (case V.Map.find (env, x)
                 of SOME(V(ty, x')) => CL.mkDecl(ty, x', NONE) :: stms
                  | NONE => raise Fail(concat["mkDecl(", V.name x, ", _)"])
                (* end case *))
          val stms = List.foldr mkDecl stms locals
          in
            (env, stms)
          end

    val trBlock = trBlk

  end