// A Small LLVM Compiler for a Simple Functional Language

// (includes an external lexer and parser)

//

//

// call with 

//

//     amm fun_llvm.sc main fact.fun

//     amm fun_llvm.sc main defs.fun

//

// or

//

//     amm fun_llvm.sc write fact.fun

//     amm fun_llvm.sc write defs.fun

//

//       this will generate an .ll file. 

//

// or 

//

//     amm fun_llvm.sc run fact.fun

//     amm fun_llvm.sc run defs.fun

//

//

// You can interpret an .ll file using lli, for example

//

//      lli fact.ll

//

// The optimiser can be invoked as

//

//      opt -O1 -S in_file.ll > out_file.ll

//      opt -O3 -S in_file.ll > out_file.ll

//

// The code produced for the various architectures can be obtain with

//   

//   llc -march=x86 -filetype=asm in_file.ll -o -

//   llc -march=arm -filetype=asm in_file.ll -o -  

//

// Producing an executable can be achieved by

//

//    llc -filetype=obj in_file.ll

//    gcc in_file.o -o a.out

//    ./a.out

import $file.fun_tokens, fun_tokens._

import $file.fun_parser, fun_parser._ 

// for generating new labels

var counter = -1

def Fresh(x: String) = {

  counter += 1

  x ++ "_" ++ counter.toString()

}

// Internal CPS language for FUN

abstract class KExp

abstract class KVal

case class KVar(s: String) extends KVal

case class KNum(i: Int) extends KVal

case class Kop(o: String, v1: KVal, v2: KVal) extends KVal

case class KCall(o: String, vrs: List[KVal]) extends KVal

case class KWrite(v: KVal) extends KVal

case class KLet(x: String, e1: KVal, e2: KExp) extends KExp {

  override def toString = s"LET $x = $e1 in \n$e2" 

}

case class KIf(x1: String, e1: KExp, e2: KExp) extends KExp {

  def pad(e: KExp) = e.toString.replaceAll("(?m)^", "  ")

  override def toString = 

     s"IF $x1\nTHEN\n${pad(e1)}\nELSE\n${pad(e2)}"

}

case class KReturn(v: KVal) extends KExp

// some functions for drawing KVal-trees 

// inspired by William Bradford Larcombe

def draw_vals(vs: List[KVal], prefix: String) : String = {

  val vsi = vs.iterator

  vsi.map(v => draw_val(v, prefix, vsi.hasNext)).mkString 

}

def draw_val(k: KVal, prefix: String, more: Boolean) : String = {

  val full_prefix = s"$prefix${if more then "├" else "└"}"

  val childPrefix = s"$prefix${if more then "│" else ""}  "

  s"\n${full_prefix}" ++ 

  (k match {

    case KVar(x) => x

    case KNum(n) => n.toString

    case Kop(op, v1 , v2) => s"KOp($op) ${draw_vals(List(v1, v2), childPrefix)}" 

    case KCall(nme, as) => s"KCall($nme) ${draw_vals(as, childPrefix)}" 

    case KWrite(v) => s"KWrite ${draw_val(v, childPrefix, false)}" 

  })

}

def draw(k: KVal) = "│" ++ draw_val(k, "", false)

// val k1 = KVar("foo")

// val k2 = KNum(1)

// val k3 = Kop("-", Kop("+", k1, k2), KNum(2))

// println(draw(k3).mkString)

// println(draw(KCall("bar", List(k1,k2,k3,k2,k1))).mkString)

// CPS translation from Exps to KExps using a

// continuation k.

def CPS(e: Exp)(k: KVal => KExp) : KExp = e match {

  case Var(s) => k(KVar(s)) 

  case Num(i) => k(KNum(i))

  case Aop(o, e1, e2) => {

    val z = Fresh("tmp")

    CPS(e1)(y1 => 

      CPS(e2)(y2 => KLet(z, Kop(o, y1, y2), k(KVar(z)))))

  }

  case If(Bop(o, b1, b2), e1, e2) => {

    val z = Fresh("tmp")

    CPS(b1)(y1 => 

      CPS(b2)(y2 => 

        KLet(z, Kop(o, y1, y2), KIf(z, CPS(e1)(k), CPS(e2)(k)))))

  }

  case Call(name, args) => {

    def aux(args: List[Exp], vs: List[KVal]) : KExp = args match {

      case Nil => {

          val z = Fresh("tmp")

          KLet(z, KCall(name, vs), k(KVar(z)))

      }

      case e::es => CPS(e)(y => aux(es, vs ::: List(y)))

    }

    aux(args, Nil)

  }

  case Sequence(e1, e2) => 

    CPS(e1)(_ => CPS(e2)(y2 => k(y2)))

  case Write(e) => {

    val z = Fresh("tmp")

    CPS(e)(y => KLet(z, KWrite(y), k(KVar(z))))

  }

}   

//initial continuation

def CPSi(e: Exp) = CPS(e)(KReturn)

//some testcases:

// (1 + 2) * 3

println(CPSi(Aop("*", Aop("+", Num(1), Num(2)), Num(3))).toString)

// 3 * (1 + 2)

println(CPSi(Aop("*", Num(3), Aop("+", Num(1), Num(2)))).toString)

//some testcases:

// numbers and vars   

println(CPSi(Num(1)).toString)

println(CPSi(Var("z")).toString)

//  a * 3

val e1 = Aop("*", Var("a"), Num(3))

println(CPSi(e1).toString)

// (a * 3) + 4

val e2 = Aop("+", Aop("*", Var("a"), Num(3)), Num(4))

println(CPSi(e2).toString)

// 2 + (a * 3)

val e3 = Aop("+", Num(2), Aop("*", Var("a"), Num(3)))

println(CPSi(e3).toString)

//(1 - 2) + (a * 3)

val e4 = Aop("+", Aop("-", Num(1), Num(2)), Aop("*", Var("a"), Num(3)))

println(CPSi(e4).toString)

// 3 + 4 ; 1 * 7

val es = Sequence(Aop("+", Num(3), Num(4)),

                  Aop("*", Num(1), Num(7)))

println(CPSi(es).toString)

// if (1 == 1) then 3 else 4

val e5 = If(Bop("==", Num(1), Num(1)), Num(3), Num(4))

println(CPSi(e5).toString)

// if (1 == 1) then 3 + 7 else 4 * 2

val ei = If(Bop("==", Num(1), Num(1)), 

                Aop("+", Num(3), Num(7)),

                Aop("*", Num(4), Num(2)))

println(CPSi(ei).toString)

// if (10 != 10) then e5 else 40

val e6 = If(Bop("!=", Num(10), Num(10)), e5, Num(40))

println(CPSi(e6).toString)

// foo(3)

val e7 = Call("foo", List(Num(3)))

println(CPSi(e7).toString)

// foo(3 * 1, 4, 5 + 6)

val e8 = Call("foo", List(Aop("*", Num(3), Num(1)), 

                          Num(4), 

                          Aop("+", Num(5), Num(6))))

println(CPSi(e8).toString)

// a * 3 ; b + 6

val e9 = Sequence(Aop("*", Var("a"), Num(3)), 

                  Aop("+", Var("b"), Num(6)))

println(CPSi(e9).toString)

val e10 = Aop("*", Aop("+", Num(1), Call("foo", List(Var("a"), Num(3)))), Num(4))

println(CPSi(e10).toString)

// convenient string interpolations 

// for instructions, labels and methods

import scala.language.implicitConversions

import scala.language.reflectiveCalls

extension (sc: StringContext) {

    def i(args: Any*): String = "   " ++ sc.s(args:_*) ++ "\n"

    def l(args: Any*): String = sc.s(args:_*) ++ ":\n"

    def m(args: Any*): String = sc.s(args:_*) ++ "\n"

}

// mathematical and boolean operations

def compile_op(op: String) = op match {

  case "+" => "add i32 "

  case "*" => "mul i32 "

  case "-" => "sub i32 "

  case "/" => "sdiv i32 "

  case "%" => "srem i32 "

  case "==" => "icmp eq i32 "

  case "<=" => "icmp sle i32 "     // signed less or equal

  case "<"  => "icmp slt i32 "     // signed less than

}

// compile K values

def compile_val(v: KVal) : String = v match {

  case KNum(i) => s"$i"

  case KVar(s) => s"%$s"

  case Kop(op, x1, x2) => 

    s"${compile_op(op)} ${compile_val(x1)}, ${compile_val(x2)}"

  case KCall(x1, args) => 

    s"call i32 @$x1 (${args.map(compile_val).mkString("i32 ", ", i32 ", "")})"

  case KWrite(x1) =>

    s"call i32 @printInt (i32 ${compile_val(x1)})"

}

// compile K expressions

def compile_exp(a: KExp) : String = a match {

  case KReturn(v) =>

    i"ret i32 ${compile_val(v)}"

  case KLet(x: String, v: KVal, e: KExp) => 

    i"%$x = ${compile_val(v)}" ++ compile_exp(e)

  case KIf(x, e1, e2) => {

    val if_br = Fresh("if_branch")

    val else_br = Fresh("else_branch")

    i"br i1 %$x, label %$if_br, label %$else_br" ++

    l"\n$if_br" ++

    compile_exp(e1) ++

    l"\n$else_br" ++ 

    compile_exp(e2)

  }

}

val prelude = """

@.str = private constant [4 x i8] c"%d\0A\00"

declare i32 @printf(i8*, ...)

define i32 @printInt(i32 %x) {

   %t0 = getelementptr [4 x i8], [4 x i8]* @.str, i32 0, i32 0

   call i32 (i8*, ...) @printf(i8* %t0, i32 %x) 

   ret i32 %x

}

"""

// compile function for declarations and main

def compile_decl(d: Decl) : String = d match {

  case Def(name, args, body) => { 

    m"define i32 @$name (${args.mkString("i32 %", ", i32 %", "")}) {" ++

    compile_exp(CPSi(body)) ++

    m"}\n"

  }

  case Main(body) => {

    m"define i32 @main() {" ++

    compile_exp(CPS(body)(_ => KReturn(KNum(0)))) ++

    m"}\n"

  }

}

// main compiler functions

def compile(prog: List[Decl]) : String = 

  prelude ++ (prog.map(compile_decl).mkString)

@main

def main(fname: String) = {

    val path = os.pwd / fname

    val file = fname.stripSuffix("." ++ path.ext)

    val tks = tokenise(os.read(path))

    val ast = parse_tks(tks)

    println(compile(ast))

}

@main

def write(fname: String) = {

    val path = os.pwd / fname

    val file = fname.stripSuffix("." ++ path.ext)

    val tks = tokenise(os.read(path))

    val ast = parse_tks(tks)

    val code = compile(ast)

    os.write.over(os.pwd / (file ++ ".ll"), code)

}

@main

def run(fname: String) = {

    val path = os.pwd / fname

    val file = fname.stripSuffix("." ++ path.ext)

    write(fname)  

    os.proc("llc", "-filetype=obj", file ++ ".ll").call()

    os.proc("gcc", file ++ ".o", "-o", file ++ ".bin").call()

    os.proc(os.pwd / (file ++ ".bin")).call(stdout = os.Inherit)

    println(s"done.")

}

// CPS functions

/*

def fact(n: Int) : Int = 

  if (n == 0) 1 else n * fact(n - 1)

fact(6)

def factT(n: Int, acc: Int) : Int =

  if (n == 0) acc else factT(n - 1, acc * n)

factT(6, 1)

def factC(n: Int, ret: Int => Int) : Int = {

  if (n == 0) ret(1) 

  else factC(n - 1, x => ret(x * n))

}

fibC(10, x => {println(s"Result: $x") ; 1})

*/