functor Emit(I: IL) = struct
  structure I = I

  structure P = I.P
  structure D = P.D
  structure PP = P.P

  val ip = I

  val file = ref NONE

  datatype reg =
    Rax | Rbx | Rcx | Rdx | Rsi | Rdi | Rbp | Rsp | R8 |
    R9 | R10 | R11 | R12 | R13 | R14 | R15

  datatype vConst = VConst of word | VAddrConst of int * word
  datatype vrType =
    VtConst of vConst | VtReg of reg | VtStack of int | VtUnk

  datatype affinity = AfHard of reg | AfSoft of int list | AfUnk

  val regs = [
    (Rcx, 0),
    (Rsi, 1),
    (Rdi, 2),
    (R8, 3),
    (R9, 4),
    (R10, 5),
    (R11, 6),

    (Rbx, 7),
    (R12, 8),
    (R13, 9),
    (R14, 10),
    (R15, 11),

    (Rax, 12),
    (Rdx, 13),
    (Rsp, 14),
    (Rbp, 15)
  ]

  val callerSavedRegs = 7
  val usedRegNum = 12

  fun reg2idx reg =
    case List.find (fn (r, _) => r = reg) regs of
      NONE => raise Unreachable
    | SOME (_, idx) => idx

  fun idx2reg idx =
    case List.find (fn (_, i) => i = idx) regs of
      NONE => raise Unreachable
    | SOME (r, _) => r

  local
    fun output s =
    let
      val outstream = valOf $ !file
    in
      TextIO.output (outstream, s)
    end

    val ctx = ((false, makePrintfBase output),
      fn (_: bool * ((string -> unit) * (unit -> unit))) => ())
  in
    fun fprint g = Fold.fold ctx g
  end

  fun fprintt g = fprint `"\t" g

  fun fprinttn g =
    fprintt (fn (a, _) => g (a, fn (_, out) => (Printf out `"\n" %)))

  fun handleBSS objsZI =
  let
    val () = fprint `"section .bss\n" %

    fun handleObj (id, _, t, _, _) =
    let
      val align = P.alignOfType t
      val size = P.sizeOfType t
    in
      fprinttn `"align\t" W align %;
      fprint PP.? id `":\tresb " W size `"\n" %
    end
  in
    List.app handleObj objsZI
  end

  fun dd size w =
  let
    val cmd =
      case size of
        0w1 => "db"
      | 0w2 => "dw"
      | 0w4 => "dd"
      | 0w8 => "dq"
      | _ => raise Unreachable
  in
    fprint `cmd `" " W w %
  end

  fun emitAggrLayout id =
  let
    val (_, size, layout) = D.get P.iniLayouts id

    val () = fprint `"\n" %

    fun getPadding offset t [] = size - (offset + P.sizeOfType t)
      | getPadding offset t ({ offset = offset', ... } :: _) =
        offset' - (offset + P.sizeOfType t)

    fun emitScalars ({ offset, t, value } :: tail) =
    let
      val () = fprint `"\t" %
      val () = dd (P.sizeOfType t) value
      val padding = getPadding offset t tail
    in
      if padding > 0w0 then
        fprint `"\n\tresb " W padding `"\n" %
      else
        fprint `"\n" %;
      emitScalars tail
    end
      | emitScalars [] = ()
  in
    emitScalars layout
  end

  fun handleData objs =
  let
    val () = fprint `"section .data\n" %

    fun emitLayout (id, _, t, ini, _) =
    let
      val align = P.alignOfType t
      val () = fprinttn `"align\t" W align %
      val () = fprint PP.? id `":" %
    in
      case ini of
        P.CiniLayout id => emitAggrLayout id
      | P.CiniExpr _ => raise Unreachable
    end
  in
    List.app emitLayout objs
  end

  fun handleStrlits strlits =
  let
    fun f id = fprint `".S" I id `":\tdb " `(PP.?? id) `", 0\n" %
  in
    fprint `"\n" %;
    List.app f strlits
  end

  fun handleLocalIniLayouts () =
  let
    fun f (_, (true, _, _)) = ()
      | f (n, (false, _, _)) = (
        fprint `"\talign 16\n" %;
        fprint `".I" I n `":" %;
        emitAggrLayout n
      )
  in
    D.appi f P.iniLayouts
  end

  fun extendEnd (iStart, iEnd) ops labels =
  let
    fun loop idx iEnd =
      if idx = D.length ops then
        iEnd
      else
        let
          val (ins, _) = D.get ops idx
        in
          case ins of
            SOME (I.IrJmp lid) | SOME (I.IrJz (_, lid)) |
            SOME (I.IrJnz (_, lid)) =>
            let
              val ldest = valOf $ D.get labels lid

              val iEnd =
                if ldest > iStart andalso ldest < iEnd then
                  idx
                else
                  iEnd
            in
              loop (idx + 1) iEnd
            end
          | _ => loop (idx + 1) iEnd
        end
  in
    loop iEnd iEnd
  end

  fun computeIntLocal (s, e) firstDef ops labels =
  let
    val e = extendEnd (s, e) ops labels

    val (_, li) = D.get ops firstDef
  in
    case li of
      SOME (startL, endL) =>
      let
        val (startLoop, endLoop) =
          (valOf $ D.get labels startL, valOf $ D.get labels endL)

        val s = if s < startLoop then s else startLoop
        val e = if e > endLoop then e else endLoop
      in
        (s, e)
      end
    | _ => (s, e)
  end

  fun getBasicInt [] _ = raise Unreachable
    | getBasicInt defs [] = (List.last defs, hd defs + 1)
    | getBasicInt defs use =
    let
      val (firstDef, lastDef) = (List.last defs, hd defs)
      val (firstUse, lastUse) = (List.last use, hd use)

      val first = if firstDef < firstUse then firstDef else firstUse - 1
      val last = if lastDef < lastUse then lastUse else lastDef + 1
    in
      (first, last)
    end

  fun computeInt (I.Fi { vregs, ops, localBound, labels, ... }) var =
  let
    val { defs, use, ... } = D.get vregs var
    val (iStart, iEnd) = getBasicInt defs use

    val (iStart, iEnd) =
      if var < localBound then
        computeIntLocal (iStart, iEnd) (List.last defs) ops labels
      else
        (iStart, iEnd)
  in
    (var, iStart, iEnd)
  end

  fun computeInts F vars = List.map (computeInt F) vars

  fun printInts ints =
  let
    val () = printfn `"\nsorted intervals:\n" %
    fun p (id, s, e) = printfn `"id: %" I id `" {" I s `", " I e `"}" %
  in
    List.app p ints
  end

  fun updAff arr idx aff =
  let
    val (_, vt) = Array.sub (arr, idx)
  in
    Array.update (arr, idx, (aff, vt))
  end

  datatype insAff = IaNone | IaHard of (int * reg) list
                  | IaSoft of int * int list

  fun parNum2reg pr =
    case pr of
      0 => Rdi
    | 1 => Rsi
    | 2 => Rdx
    | 3 => Rcx
    | 5 => R8
    | 6 => R9
    | _ => raise Unreachable

  fun getInsAff (SOME ins) =
  let
    fun tr (rd, rs1, rs2) = IaSoft (rd, [rs1, rs2])

    fun setAff (rd, I.SaVReg rs) = IaSoft (rd, [rs])
      | setAff _ = IaNone

    fun fcallAff args =
    let
      fun collect idx (arg :: args) acc =
        collect (idx + 1) args ((arg, parNum2reg idx) :: acc)
        | collect _ [] acc = rev acc
    in
      IaHard $ collect 0 args []
    end
  in
    case ins of
      I.IrSet p => setAff p
    | I.IrAdd t => tr t
    | I.IrSub t => tr t
    | I.IrMul t => tr t
    | I.IrIMul t => tr t
    | I.IrDiv t => tr t
    | I.IrIDiv t => tr t
    | I.IrMod t => tr t
    | I.IrIMod t => tr t
    | I.IrShl t => tr t
    | I.IrShr t => tr t
    | I.IrSar t => tr t
    | I.IrAnd t => tr t
    | I.IrOr t => tr t
    | I.IrXor t => tr t
    | I.IrEq t => tr t
    | I.IrNeq t => tr t
    | I.IrCmpul t => tr t
    | I.IrCmpug t => tr t
    | I.IrCmpule t => tr t
    | I.IrCmpuge t => tr t
    | I.IrCmpsl t => tr t
    | I.IrCmpsg t => tr t
    | I.IrCmpsle t => tr t
    | I.IrCmpsge t => tr t

    | I.IrExtZero _ | I.IrExtSign _
    | I.IrLoad _ | I.IrStore _ | I.IrJmp _
    | I.IrJz _ | I.IrJnz _ | I.IrNopLabel _
    | I.IrNop _ | I.IrRet _ | I.IrAlloc _
    | I.IrCopy _ => IaNone
    | I.IrFcall (_, _, args) => fcallAff args
  end
   | getInsAff NONE = IaNone

  fun updateSoftAff rinfo rd rss =
  let
    fun sort [r] = [r]
      | sort [rs1, rs2] = if rs1 < rs2 then [rs1, rs2] else [rs2, rs1]
      | sort _ = raise Unreachable

    fun isNotConst rv =
    let
      val (_, vt) = Array.sub (rinfo, rv)
    in
      case vt of
        VtConst _ => false
      | _ => true
    end

    val (aff, vt) = Array.sub (rinfo, rd)
    val rss = List.filter isNotConst $ sort rss

    fun insertSorted ins [] = ins
      | insertSorted [] acc = acc
      | insertSorted (x :: xs) (y :: ys) =
        if x < y then
          x :: insertSorted xs (y :: ys)
        else
          y :: insertSorted (x :: xs) ys

    val aff =
      case aff of
        AfUnk => AfSoft rss
      | AfSoft affs => AfSoft $ insertSorted rss affs
      | AfHard _ => aff
  in
    Array.update (rinfo, rd, (aff, vt))
  end

  fun updateHardAff rinfo hards =
  let
    fun f (rd, reg) =
    let
      val (aff, vt) = Array.sub (rinfo, rd)

      val aff =
        case aff of
          AfUnk | AfSoft _ => AfHard reg
        | AfHard _ => raise Unreachable
    in
      Array.update (rinfo, rd, (aff, vt))
    end
  in
    List.app f hards
  end

  fun compAffinity rinfo ops paramNum =
  let
    fun compParams idx =
      if idx = paramNum then
        ()
      else
        let
          val reg = parNum2reg idx
        in
          updAff rinfo idx (AfHard reg);
          compParams (idx + 1)
        end
    val () = compParams 0

    fun loop idx =
      if idx = D.length ops then
        ()
      else
        let
          val (ins, _) = D.get ops idx
        in
          case getInsAff ins of
            IaNone => ()
          | IaSoft (rd, rss) => updateSoftAff rinfo rd rss
          | IaHard hards => updateHardAff rinfo hards;
          loop (idx + 1)
        end
  in
    loop 0
  end

  fun prepareRegInfo paramNum ops vregs =
  let
    val rinfo = Array.array (D.length vregs, (AfUnk, VtUnk))

    fun transfer idx acc =
      if idx = D.length vregs then
        rev acc
      else
      let
        val (vt, cand) =
          case #t $ D.get vregs idx of
            I.RtRem => (VtUnk, NONE)
          | I.RtConst w => (VtConst (VConst w), NONE)
          | I.RtAddrConst (id, w) => (VtConst (VAddrConst (id, w)), NONE)
          | I.RtReg => (VtUnk, SOME idx)
      in
        Array.update (rinfo, idx, (AfUnk, vt));
        transfer (idx + 1) (if isSome cand then valOf cand :: acc else acc)
      end

    val toAlloc = transfer 0 []
  in
    compAffinity rinfo ops paramNum;
    (toAlloc, rinfo)
  end

  fun preg reg out =
  let
    val s =
      case reg of
        Rax => "rax"
      | Rbx => "rbx"
      | Rcx => "rcx"
      | Rdx => "rdx"
      | Rsi => "rsi"
      | Rdi => "rdi"
      | Rbp => "rbp"
      | Rsp => "rsp"
      | R8 => "r8"
      | R9 => "r9"
      | R10 => "r10"
      | R11 => "r11"
      | R12 => "r12"
      | R13 => "r13"
      | R14 => "r14"
      | R15 => "r15"
  in
    Printf out `s %
  end

  val Preg = fn z => bind A1 preg z

  fun affPrint rinfo =
  let
    fun pv idx out = Printf out `"%" I idx %

    fun p (idx, (aff, _)) =
    let
      val () = printf `"%" I idx %
    in
      case aff of
       AfUnk => printfn `" = unk" %
     | AfHard reg => printfn `" <- " Preg reg %
     | AfSoft rss => printfn `" <- " Plist pv rss (", ", true, 1) %
    end
  in
    Array.appi p rinfo
  end

  fun sort _ [] = []
    | sort _ [x] = [x]
    | sort le l =
    let
      fun divide [] accp = accp
        | divide [x] (acc1, acc2) = (x :: acc1, acc2)
        | divide (x :: y :: tail) (acc1, acc2) =
          divide tail (x :: acc1, y :: acc2)
      val (part1, part2) = divide l ([], [])
      val part1 = sort le part1
      val part2 = sort le part2

      fun merge [] [] acc = acc
        | merge [] ys acc = rev $ List.revAppend (ys, acc)
        | merge xs [] acc = rev $ List.revAppend (xs, acc)
        | merge (x :: xs) (y :: ys) acc =
            if le (x, y) then
              merge xs (y :: ys) (x :: acc)
            else
              merge (x :: xs) ys (y :: acc)
    in
      merge part1 part2 []
    end

  fun updateI i = fn z =>
  let
    fun from rinfo active pool intervals stackCand =
      { rinfo, active, pool, intervals, stackCand }
    fun to f { rinfo, active, pool, intervals, stackCand } =
      f rinfo active pool intervals stackCand
  in
    FRU.makeUpdate5 (from, from, to) i
  end z

  fun returnToPool pool reg =
  let
    val idx = reg2idx reg
  in
    Array.update (pool, idx, NONE)
  end

  fun expireOne { rinfo, active, pool, ... } (_, start, _) =
    case !active of
      [] => false
    | (j, startp, endp) :: acts =>
      if endp > start then
        false
      else
        let
          val (_, vt) = Array.sub (rinfo, j)
          val reg = case vt of VtReg reg => reg | _ => raise Unreachable

          val () = printfn `"III!!! interval %"
              ip j `"(" ip startp `", " ip endp `") "
              `"with " Preg reg `" has expired" %
        in
          returnToPool pool reg;
          active := acts;
          true
        end

  fun expireOld (I as { active, ... }) int =
    let
      fun loop I =
        case expireOne I int of
          false => ()
        | true => loop I
    in
      case !active of
        [] => ()
      | _ => loop I
    end

  fun addToActive int [] = [int]
    | addToActive (I as (_, _, e1)) (act :: acts) =
    if e1 < #3 act then
      (I :: act :: acts)
    else
      act :: addToActive I acts

  fun updReg arr idx reg =
  let
    val (aff, _) = Array.sub (arr, idx)
  in
    Array.update (arr, idx, (aff, reg))
  end

  fun assignFirstReg poff { rinfo, pool, ... } vr =
  let
    fun loop idx =
      if idx = Array.length pool then
        raise Unreachable
      else
        let
          val user = Array.sub (pool, idx)
        in
          case user of
            SOME _ => loop (idx + 1)
          | NONE =>
            let
              val () = Array.update (pool, idx, SOME vr);
              val reg = idx2reg idx

              val () = printfn R poff
                `"assigned (first) reg " Preg reg `" to %" ip vr %
            in
              updReg rinfo vr (VtReg reg)
            end
        end
  in
    loop 0
  end

  fun freeRegList pool =
  let
    fun loop idx acc =
      if idx = Array.length pool then
        rev acc
      else
        case Array.sub (pool, idx) of
          NONE => loop (idx + 1) (idx2reg idx :: acc)
        | SOME _ => loop (idx + 1) acc
  in
    loop 0 []
  end

  fun getAffRegList rinfo affs =
  let
    fun loop [] acc = rev acc
      | loop (vr :: vrs) acc =
      let
        val (_, vt) = Array.sub (rinfo, vr)
      in
        case vt of
          VtReg r => loop vrs (r :: acc)
        | _ => loop vrs acc
      end
  in
    loop affs []
  end

  fun findCommonRegs l1 l2 =
  let
    val l1 = sort (fn (r1, r2) => reg2idx r1 <= reg2idx r2) l1
    val l2 = sort (fn (r1, r2) => reg2idx r1 <= reg2idx r2) l2

    fun intersection [] _ = []
      | intersection _ [] = []
      | intersection (x :: xs) (y :: ys) =
        case Int.compare (reg2idx x, reg2idx y) of
          LESS => intersection xs (y :: ys)
        | EQUAL => x :: intersection xs ys
        | GREATER => intersection (x :: xs) ys
  in
    intersection l1 l2
  end

  fun assignSoftReg poff affs (I as { rinfo,  pool, ... }) vr =
  let
    val () = printfn R poff
      `"trying to assign register (by affinity) to %" ip vr %

    val regs = freeRegList pool
    val affRegs = getAffRegList rinfo affs
    val common = findCommonRegs regs affRegs

    val () = printfn R (poff + 1)
      `"free registers: " Plist preg regs (", ", true, 0) %
    val () = printfn R (poff + 1)
      `"affinity registers: " Plist preg affRegs (", ", true, 0) %
  in
    case common of
      [] =>
      let
        val () = printfn R (poff + 1) `"affinity was not satisfied" %
      in
        assignFirstReg (poff + 2) I vr
      end
    | (reg :: _) =>
      let
      in
        updReg rinfo vr (VtReg reg);
        Array.update (pool, reg2idx reg, SOME vr);
        printfn R (poff + 1)
          `"assigned (by affinity) reg " Preg reg `" to %" ip vr %;
        printfn R (poff + 1)
          `"free registers: " Plist preg (freeRegList pool) (", ", true, 0) %
      end
  end

  fun putToStack poff { rinfo, stackCand, ... } vr =
  let
    val () = printfn R poff
      `"puting %" ip vr `" to stack: " ip (!stackCand) %
  in
    updReg rinfo vr (VtStack (!stackCand));
    stackCand := !stackCand - 8
  end

  fun assignHardReg poff (I as { rinfo,  pool, ... }) vr reg =
  let
    val () = printfn R poff
      `"trying to assign hard reg " A1 preg reg `" to %" ip vr %

    val regIdx = reg2idx reg
    val user = Array.sub (pool, regIdx)

    fun setOurReg () =
    let
      val () = printfn R (poff + 1) `"reg assigned" %
    in
      Array.update (pool, regIdx, SOME vr);
      updReg rinfo vr (VtReg reg)
    end
  in
    case user of
      NONE => setOurReg ()
    | SOME u =>
      let
        val () = printfn R (poff + 1) `"reg is taken by %" ip u %
        val (aff, _) = Array.sub (rinfo, u)
      in
        case aff of
          AfHard _ => raise Unreachable
        | AfSoft affs => assignSoftReg poff affs I u
        | AfUnk => assignFirstReg poff I u
        ;
        setOurReg ()
      end
  end

  fun assignReg (I as { rinfo, ... }) (vr, _, _) =
  let
    val (aff, _) = Array.sub (rinfo, vr)
  in
    case aff of
      AfUnk => assignFirstReg 0 I vr
    | AfSoft affs => assignSoftReg 0 affs I vr
    | AfHard reg => assignHardReg 0 I vr reg
  end

  fun getPool () = Array.array (usedRegNum, NONE)

  fun changeInActive active newInt oldVr =
  let
    val a = !active
    val a = List.filter (fn (v, _, _) => v <> oldVr) a
  in
    active := addToActive newInt a
  end

  fun expropriateReg (I as { rinfo, pool, active, ... }) int reg =
  let
    val vr = #1 int

    val regIdx = reg2idx reg
    val u = valOf $ Array.sub (pool, regIdx)

    val (uAff, _) = Array.sub (rinfo, u)
    val () =
      case uAff of
        AfHard _ => raise Unreachable
      | _ => ()

    val () = putToStack 1 I u
    val () = Array.update (pool, regIdx, SOME vr)
    val () = updReg rinfo vr (VtReg reg)
  in
    changeInActive active int u
  end

  fun userIdx pool vr =
  let
    fun loop idx =
      if idx = Array.length pool then
        raise Unreachable
      else
        case Array.sub (pool, idx) of
          SOME u =>
            if u = vr then
              idx
            else
              loop (idx + 1)
        | NONE => loop (idx + 1)
  in
    loop 0
  end

  fun spillAtInterval (I as { rinfo, active, pool, ... }) int =
  let
    val spill = List.last (!active)

    val vr = #1 int
    val (ourAff, _) = Array.sub (rinfo, vr)

    fun isNotHard vr =
      case #1 $ Array.sub (rinfo, vr) of
        AfHard _ => false
      | _ => true

    val () = printfn `"SpilAtInt" %
    val () = printfn R 0
      `"free registers: " Plist preg (freeRegList pool) (", ", true, 0) %
  in
    case ourAff of
      AfHard reg => expropriateReg I int reg
    | _ =>
      if #3 spill > #3 int andalso isNotHard (#1 spill) then
        let
          val idx = userIdx pool (#1 spill)
          val () = printfn `"spilling!!!" %
        in
          Array.update (pool, idx, SOME vr);
          updReg rinfo vr (VtReg $ idx2reg idx);
          putToStack 1 I (#1 spill);
          changeInActive active int (#1 spill)
        end
      else
        putToStack 0 I vr
  end

  fun linearscan rinfo ints =
  let
    fun incStart ((_, start1, _), (_, start2, _)) = start1 <= start2
    val ints = sort incStart ints

    val () = printInts ints

    fun loop _ [] = ()
      | loop (I as { active, ... }) (int :: ints) =
      let
        val () = printfn `"\n\ninspectiing interval "
            ip (#1 int) `": (" ip (#2 int) `", " ip (#3 int) `")" %

        val () = expireOld I int

        val () =
          if length (!active) = usedRegNum then
            spillAtInterval I int
          else
            let
              val () = assignReg I int
            in
              active := addToActive int (!active)
            end
      in
        loop I ints
      end
  in
    loop { active = ref [], pool = getPool (), rinfo,
      stackCand = ref (~8) } ints
  end

  fun printAllocVar rinfo v =
  let
    val () = printf `"%" I v `": " %
    val (_, vt) = Array.sub (rinfo, v)
  in
    case vt of
      VtStack off => printfn `"stack " I off %
    | VtReg reg => printfn `"reg " A1 preg reg %
    | VtConst _ | VtUnk => raise Unreachable
  end

  fun printAlloced rinfo toAlloc =
  let
    val () = printfn `"\nallocated:\n" %
  in
    List.app (printAllocVar rinfo) toAlloc
  end

  fun getUsedRegs rinfo =
  let
    val regs = Array.array (usedRegNum, false)

    fun loop idx =
      if idx = Array.length rinfo then
        ()
      else
        let
          val (_, vt) = Array.sub (rinfo, idx)
        in
          case vt of
            VtReg reg => Array.update (regs, reg2idx reg, true)
          | _ => ();
          loop (idx + 1)
        end
    val () = loop 0

    fun collect idx acc =
      if idx = usedRegNum then
        acc
      else
        if Array.sub (regs, idx) then
          collect (idx + 1) (idx2reg idx :: acc)
        else
          collect (idx + 1) acc
  in
    collect 0 []
  end

  fun getRegsToSave rinfo =
  let
    val regs = getUsedRegs rinfo
  in
    List.filter (fn r => reg2idx r >= callerSavedRegs) regs
  end

  fun initMap len =
  let
    open Array
    val map = array (len, array (callerSavedRegs, NONE))
    val i = ref 1
  in
    while !i < len do (
        update (map, !i, array (callerSavedRegs, NONE));
        i := !i + 1
    );
    map
  end

  fun computeMap len intervals rinfo =
  let
    val map = initMap len

    fun addInt (vr, startp, endp) =
      case #2 $ Array.sub (rinfo, vr) of
        VtReg reg =>
          let
            fun f idx =
              if reg2idx reg >= callerSavedRegs orelse idx = endp then
                ()
              else
                let
                  val row = Array.sub (map, idx)
                in
                  Array.update (row, reg2idx reg, SOME vr);
                  f (idx + 1)
                end
          in
            f (startp + 1)
          end
      | _ => ()
  in
    List.app addInt intervals;
    map
  end

  fun printMap map =
  let
    val () = printfn `"Register map\n" %

    fun printHeader idx =
      if idx = callerSavedRegs then
        printf `"\n" %
      else (
        printfp 5 `" " Preg (idx2reg idx) `" " %;
        printHeader (idx + 1)
      )

    val () = printf `"      " %
    val () = printHeader 0

    fun printRow (idx, row) =
    let
      val () = printf Ip 4 idx `": " %

      fun loop idx =
        if idx = callerSavedRegs then
          printf `"\n" %
        else (
          case Array.sub (row, idx) of
            NONE => printf `"     " %
          | SOME vr => printfp 5 `"%" I vr `" " %;
          loop (idx + 1)
        )
    in
      loop 0
    end
  in
    Array.appi printRow map
  end

  fun regAlloc (F as I.Fi { vregs, ops, paramNum, ... }) =
  let
    val (toAlloc, regInfo) = prepareRegInfo paramNum ops vregs
    val () = printfn `"for alloc: " Plist i toAlloc (", ", true, 0) %

    val () = affPrint regInfo

    val intervals = computeInts F toAlloc

    val () = linearscan regInfo intervals
    val () = printAlloced regInfo toAlloc

    val regsToSave = getRegsToSave regInfo
    val () = printfn
      `"registers to save: " Plist preg regsToSave (", ", true, 0) %

    val regMap = computeMap (D.length ops) intervals regInfo
    val () = printMap regMap
  in
    raise Unimplemented
  end

  fun emitFunc (F as I.Fi { vregs, ... }) =
  let
    val () = regAlloc F vregs
  in
    raise Unimplemented
  end

  fun openFile fname = file := SOME (TextIO.openOut fname)

  fun emit fname
    (I.Ctx { globSyms, extSyms, objsZI, objs, strlits, funcInfos, ... }) =
  let
    val () = openFile fname

    val () = List.app (fn gs => fprint `"global " PP.? gs `"\n" %) globSyms
    val () = List.app (fn es => fprint `"extern " PP.? es `"\n" %) extSyms

    val () = handleBSS objsZI
    val () = handleData objs
    val () = handleStrlits strlits
    val () = handleLocalIniLayouts ()

    val () = List.app emitFunc funcInfos
  in
    ()
  end
end