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View of /trunk/src/compiler/simplify/simplify.sml

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Revision 2356 - (download) (annotate)
Sun Apr 7 14:45:25 2013 UTC (6 years, 3 months ago) by jhr
File size: 11494 byte(s)
  Merging in bug fixes and language enhancements from the vis12 branch (via staging).
  Features include type promotion, the curl and colon operator, transpose, and functions.
(* simplify.sml
 *
 * COPYRIGHT (c) 2010 The Diderot Project (http://diderot-language.cs.uchicago.edu)
 * All rights reserved.
 *
 * Simplify the AST representation.
 *)

structure Simplify : sig

    val transform : Error.err_stream * AST.program -> Simple.program

  end = struct

    structure Ty = Types
    structure S = Simple

  (* the SimpleAST and AST currently use the same type representation, but
   * we prune out meta variables.
   *)
    val cvtTy = TypeUtil.prune

    local
      val tempName = Atom.atom "_t"
    in
    fun newTemp ty = Var.new (tempName, AST.LocalVar, cvtTy ty)
    end

  (* make a block out of a list of statements that are in reverse order *)
    fun mkBlock stms = S.Block(List.rev stms)

  (* is the given statement's continuation the syntactically following statement? *)
    fun contIsNext (AST.S_Block stms) = List.all contIsNext stms
      | contIsNext (AST.S_IfThenElse(_, s1, s2)) = contIsNext s1 orelse contIsNext s2
      | contIsNext AST.S_Die = false
      | contIsNext AST.S_Stabilize = false
      | contIsNext (AST.S_Return _) = false
      | contIsNext _ = true

    fun simplifyProgram (AST.Program dcls) = let
          val globals = ref []
          val globalInit = ref []
          val funcs = ref []
          val initially = ref NONE
          val strands = ref []
          fun setInitially init = (case !initially
                 of NONE => initially := SOME init
(* FIXME: the check for multiple initially decls should happen in type checking *)
                  | SOME _ => raise Fail "multiple initially declarations"
                (* end case *))
          fun simplifyDecl dcl = (case dcl
                 of AST.D_Input(x, desc, NONE) => let
                      val e' = S.E_Input(Var.monoTypeOf x, Var.nameOf x, desc, NONE)
                      in
                        globals := x :: !globals;
                        globalInit := S.S_Assign(x, e') :: !globalInit
                      end
                  | AST.D_Input(x, desc, SOME e) => let
                      val (stms, x') = simplifyExpToVar (e, [])
                      val e' = S.E_Input(Var.monoTypeOf x, Var.nameOf x, desc, SOME x')
                      in
                        globals := x :: !globals;
                        globalInit := S.S_Assign(x, e') :: (stms @ !globalInit)
                      end
                  | AST.D_Var(AST.VD_Decl(x, e)) => let
                      val (stms, e') = simplifyExp (e, [])
                      in
                        globals := x :: !globals;
                        globalInit := S.S_Assign(x, e') :: (stms @ !globalInit) 
                      end
                  | AST.D_Func(f, params, body) =>
                      funcs := S.Func{f=f, params=params, body=simplifyBlock body} :: !funcs
                  | AST.D_Strand info => strands := simplifyStrand info :: !strands
                  | AST.D_InitialArray(creat, iters) =>
                      setInitially (simplifyInit(true, creat, iters))
                  | AST.D_InitialCollection(creat, iters) =>
                      setInitially (simplifyInit(false, creat, iters))
                (* end case *))
          in
            List.app simplifyDecl dcls;
            S.Program{
                globals = List.rev(!globals),
                globalInit = mkBlock (!globalInit),
                funcs = List.rev(!funcs),
                init = (case !initially
(* FIXME: the check for the initially block should really happen in typechecking *)
                   of NONE => raise Fail "missing initially declaration"
                    | SOME blk => blk
                  (* end case *)),
                strands = List.rev(!strands)
              }
          end

    and simplifyInit (isArray, AST.C_Create(strand, exps), iters) = let
          val (stms, xs) = simplifyExpsToVars (exps, [])
          val creat = S.C_Create{
                  argInit = mkBlock stms,
                  name = strand,
                  args = xs
                }
          fun simplifyIter (AST.I_Range(x, e1, e2), (iters, stms)) = let
                val (stms, lo) = simplifyExpToVar (e1, stms)
                val (stms, hi) = simplifyExpToVar (e2, stms)
                in
                  ({param=x, lo=lo, hi=hi}::iters, stms)
                end
          val (iters, stms) = List.foldl simplifyIter ([], []) iters
          in
            S.Initially{
                isArray = isArray,
                rangeInit = mkBlock stms,
                iters = List.rev iters,
                create = creat
              }
          end

    and simplifyStrand (AST.Strand{name, params, state, methods}) = let
          fun simplifyState ([], xs, stms) = (List.rev xs, mkBlock stms)
            | simplifyState (AST.VD_Decl(x, e) :: r, xs, stms) = let
                val (stms, e') = simplifyExp (e, stms)
                in
                  simplifyState (r, x::xs, S.S_Assign(x, e') :: stms)
                end
          val (xs, stm) = simplifyState (state, [], [])
          in
            S.Strand{
                name = name,
                params = params,
                state = xs, stateInit = stm,
                methods = List.map simplifyMethod methods
              }
          end

    and simplifyMethod (AST.M_Method(name, body)) =
          S.Method(name, simplifyBlock body)

  (* simplify a statement into a single statement (i.e., a block if it expands
   * into more than one new statement).
   *)
    and simplifyBlock stm = mkBlock (simplifyStmt (stm, []))

  (* simplify the statement stm where stms is a reverse-order list of preceeding simplified
   * statements.  This function returns a reverse-order list of simplified statements.
   * Note that error reporting is done in the typechecker, but it does not prune unreachable
   * code.
   *)
    and simplifyStmt (stm, stms) = (case stm
           of AST.S_Block body => let
                fun simplify ([], stms) = stms
                  | simplify (stm::r, stms) = if contIsNext stm
                      then simplify (r, simplifyStmt (stm, stms))
                      else simplifyStmt (stm, stms)  (* prune unreachable statements *)
                in
                  simplify (body, stms)
                end
            | AST.S_Decl(AST.VD_Decl(x, e)) => let
                val (stms, e') = simplifyExp (e, stms)
                in
                  S.S_Assign(x, e') :: stms
                end
            | AST.S_IfThenElse(e, s1, s2) => let
                val (stms, x) = simplifyExpToVar (e, stms)
                val s1 = simplifyBlock s1
                val s2 = simplifyBlock s2
                in
                  S.S_IfThenElse(x, s1, s2) :: stms
                end
            | AST.S_Assign(x, e) => let
                val (stms, e') = simplifyExp (e, stms)
                in
                  S.S_Assign(x, e') :: stms
                end
            | AST.S_New(name, args) => let
                val (stms, xs) = simplifyExpsToVars (args, stms)
                in
                  S.S_New(name, xs) :: stms
                end
            | AST.S_Die => S.S_Die :: stms
            | AST.S_Stabilize => S.S_Stabilize :: stms
            | AST.S_Return e => let
                val (stms, x) = simplifyExpToVar (e, stms)
                in
                  S.S_Return x :: stms
                end
            | AST.S_Print args => let
                val (stms, xs) = simplifyExpsToVars (args, stms)
                in
                  S.S_Print xs :: stms
                end
          (* end case *))

    and simplifyExp (exp, stms) = (
          case exp
           of AST.E_Var x => (case Var.kindOf x
                 of Var.BasisVar => let
                      val ty = Var.monoTypeOf x
                      val x' = newTemp ty
                      val stm = S.S_Assign(x', S.E_Apply(x, [], [], ty))
                      in
                        (stm::stms, S.E_Var x')
                      end
                  | _ => (stms, S.E_Var x)
                (* end case *))
            | AST.E_Lit lit => (stms, S.E_Lit lit)
            | AST.E_Tuple es => raise Fail "E_Tuple not yet implemented"
            | AST.E_Apply(f, tyArgs, args, ty) => let
                val (stms, xs) = simplifyExpsToVars (args, stms)
                in
                  (stms, S.E_Apply(f, tyArgs, xs, ty))
                end
            | AST.E_Cons es => let
                val (stms, xs) = simplifyExpsToVars (es, stms)
                in
                  (stms, S.E_Cons xs)
                end
            | AST.E_Slice(e, indices, ty) => let (* tensor slicing *)
                val (stms, x) = simplifyExpToVar (e, stms)
                fun f ([], ys, stms) = (stms, List.rev ys)
                  | f (NONE::es, ys, stms) = f (es, NONE::ys, stms)
                  | f (SOME e::es, ys, stms) = let
                      val (stms, y) = simplifyExpToVar (e, stms)
                      in
                        f (es, SOME y::ys, stms)
                      end
                val (stms, indices) = f (indices, [], stms)
                in
                  (stms, S.E_Slice(x, indices, ty))
                end
            | AST.E_Cond(e1, e2, e3, ty) => let
              (* a conditional expression gets turned into an if-then-else statememt *)
                val result = newTemp ty
                val (stms, x) = simplifyExpToVar (e1, S.S_Var result :: stms)
                fun simplifyBranch e = let
                      val (stms, e) = simplifyExp (e, [])
                      in
                        mkBlock (S.S_Assign(result, e)::stms)
                      end
                val s1 = simplifyBranch e2
                val s2 = simplifyBranch e3
                in
                  (S.S_IfThenElse(x, s1, s2) :: stms, S.E_Var result)
                end
            | AST.E_Coerce{srcTy, dstTy, e} => let
                val (stms, x) = simplifyExpToVar (e, stms)
                val result = newTemp dstTy
                val rhs = S.E_Coerce{srcTy = cvtTy srcTy, dstTy = cvtTy dstTy, x = x}
                in
                  (S.S_Assign(result, rhs)::stms, S.E_Var result)
                end
          (* end case *))

    and simplifyExpToVar (exp, stms) = let
          val (stms, e) = simplifyExp (exp, stms)
          in
            case e
             of S.E_Var x => (stms, x)
              | _ => let
                  val x = newTemp (S.typeOf e)
                  in
                    (S.S_Assign(x, e)::stms, x)
                  end
            (* end case *)
          end

    and simplifyExpsToVars (exps, stms) = let
          fun f ([], xs, stms) = (stms, List.rev xs)
            | f (e::es, xs, stms) = let
                val (stms, x) = simplifyExpToVar (e, stms)
                in
                  f (es, x::xs, stms)
                end
          in
            f (exps, [], stms)
          end

    fun transform (errStrm, ast) = let
          val simple = simplifyProgram ast
          val _ = SimplePP.output (Log.logFile(), "simplify", simple)   (* DEBUG *)
          val simple = Inliner.transform simple
          val _ = SimplePP.output (Log.logFile(), "inlining", simple)   (* DEBUG *)
          val simple = Lift.transform simple
                handle Eval.Error msg => (Error.error(errStrm, msg); simple)
          val _ = SimplePP.output (Log.logFile(), "lifting", simple)   (* DEBUG *)
          in
            simple
          end

  end

root@smlnj-gforge.cs.uchicago.edu
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