--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/compile_arr2.scala Mon Jan 27 10:11:44 2020 +0000
@@ -0,0 +1,238 @@
+// A Small Compiler for the WHILE Language
+//
+// - includes arrays and a small parser for
+// WHILE programs
+//
+// - transpiles BF programs into WHILE programs
+// and compiles and runs them
+//
+// Call with
+//
+// scala compiler_arr.scala
+
+
+
+// the abstract syntax trees
+abstract class Stmt
+abstract class AExp
+abstract class BExp
+type Block = List[Stmt]
+
+// statements
+case object Skip extends Stmt
+case class ArrayDef(s: String, n: Int) extends Stmt
+case class If(a: BExp, bl1: Block, bl2: Block) extends Stmt
+case class While(b: BExp, bl: Block) extends Stmt
+case class Assign(s: String, a: AExp) extends Stmt // var := exp
+case class AssignA(s: String, a1: AExp, a2: AExp) extends Stmt // arr[exp1] := exp2
+case class Write(s: String) extends Stmt
+case class Read(s: String) extends Stmt
+
+// arithmetic expressions
+case class Var(s: String) extends AExp
+case class Num(i: Int) extends AExp
+case class Aop(o: String, a1: AExp, a2: AExp) extends AExp
+case class Ref(s: String, a: AExp) extends AExp
+
+// boolean expressions
+case object True extends BExp
+case object False extends BExp
+case class Bop(o: String, a1: AExp, a2: AExp) extends BExp
+
+
+// compiler headers needed for the JVM
+// (contains an init method, as well as methods for read and write)
+val beginning = """
+.class public XXX.XXX
+.super java/lang/Object
+
+.method public static write(I)V
+ .limit locals 1
+ .limit stack 2
+ getstatic java/lang/System/out Ljava/io/PrintStream;
+ iload 0
+ i2c ; Int => Char
+ invokevirtual java/io/PrintStream/print(C)V ; println(I)V => print(C)V
+ return
+.end method
+
+.method public static main([Ljava/lang/String;)V
+ .limit locals 200
+ .limit stack 200
+
+; COMPILED CODE STARTS
+
+"""
+
+val ending = """
+; COMPILED CODE ENDS
+ return
+
+.end method
+"""
+
+
+
+
+// for generating new labels
+var counter = -1
+
+def Fresh(x: String) = {
+ counter += 1
+ x ++ "_" ++ counter.toString()
+}
+
+// environments and instructions
+type Env = Map[String, Int]
+
+// convenient string interpolations
+// for instructions and labels
+import scala.language.implicitConversions
+import scala.language.reflectiveCalls
+
+implicit def sring_inters(sc: StringContext) = new {
+ def i(args: Any*): String = " " ++ sc.s(args:_*) ++ "\n"
+ def l(args: Any*): String = sc.s(args:_*) ++ ":\n"
+}
+
+def compile_op(op: String) = op match {
+ case "+" => i"iadd"
+ case "-" => i"isub"
+ case "*" => i"imul"
+}
+
+// arithmetic expression compilation
+def compile_aexp(a: AExp, env : Env) : String = a match {
+ case Num(i) => i"ldc $i"
+ case Var(s) => i"iload ${env(s)}"
+ case Aop(op, a1, a2) =>
+ compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ compile_op(op)
+ case Ref(s, a) =>
+ i"aload ${env(s)}" ++ compile_aexp(a, env) ++ i"iaload"
+}
+
+def compile_bop(op: String, jmp: String) = op match {
+ case "==" => i"if_icmpne $jmp"
+ case "!=" => i"if_icmpeq $jmp"
+ case "<" => i"if_icmpge $jmp"
+}
+
+// boolean expression compilation
+def compile_bexp(b: BExp, env : Env, jmp: String) : String = b match {
+ case True => ""
+ case False => i"goto $jmp"
+ case Bop(op, a1, a2) =>
+ compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ compile_bop(op, jmp)
+}
+
+// statement compilation
+def compile_stmt(s: Stmt, env: Env) : (String, Env) = s match {
+ case Skip => ("", env)
+ case Assign(x, a) => {
+ val index = env.getOrElse(x, env.keys.size)
+ (compile_aexp(a, env) ++ i"istore $index \t\t; $x", env + (x -> index))
+ }
+ case If(b, bl1, bl2) => {
+ val if_else = Fresh("If_else")
+ val if_end = Fresh("If_end")
+ val (instrs1, env1) = compile_block(bl1, env)
+ val (instrs2, env2) = compile_block(bl2, env1)
+ (compile_bexp(b, env, if_else) ++
+ instrs1 ++
+ i"goto $if_end" ++
+ l"$if_else" ++
+ instrs2 ++
+ l"$if_end", env2)
+ }
+ case While(b, bl) => {
+ val loop_begin = Fresh("Loop_begin")
+ val loop_end = Fresh("Loop_end")
+ val (instrs1, env1) = compile_block(bl, env)
+ (l"$loop_begin" ++
+ compile_bexp(b, env, loop_end) ++
+ instrs1 ++
+ i"goto $loop_begin" ++
+ l"$loop_end", env1)
+ }
+ case Write(x) =>
+ (i"iload ${env(x)} \t\t; $x" ++
+ i"invokestatic XXX/XXX/write(I)V", env)
+ case Read(x) => {
+ val index = env.getOrElse(x, env.keys.size)
+ (i"invokestatic XXX/XXX/read()I" ++
+ i"istore $index \t\t; $x", env + (x -> index))
+ }
+ case ArrayDef(s: String, n: Int) => {
+ val index = if (env.isDefinedAt(s)) throw new Exception("array def error") else
+ env.keys.size
+ (i"ldc $n" ++
+ i"newarray int" ++
+ i"astore $index", env + (s -> index))
+ }
+ case AssignA(s, a1, a2) => {
+ val index = if (env.isDefinedAt(s)) env(s) else
+ throw new Exception("array not defined")
+ (i"aload ${env(s)}" ++
+ compile_aexp(a1, env) ++
+ compile_aexp(a2, env) ++
+ i"iastore", env)
+ }
+}
+
+// compilation of a block (i.e. list of statements)
+def compile_block(bl: Block, env: Env) : (String, Env) = bl match {
+ case Nil => ("", env)
+ case s::bl => {
+ val (instrs1, env1) = compile_stmt(s, env)
+ val (instrs2, env2) = compile_block(bl, env1)
+ (instrs1 ++ instrs2, env2)
+ }
+}
+
+
+// main compilation function for blocks
+def compile(bl: Block, class_name: String) : String = {
+ val instructions = compile_block(bl, Map())._1
+ (beginning ++ instructions ++ ending).replaceAllLiterally("XXX", class_name)
+}
+
+
+import scala.util._
+import scala.sys.process._
+
+def time_needed[T](i: Int, code: => T) = {
+ val start = System.nanoTime()
+ for (j <- 2 to i) code
+ val result = code
+ val end = System.nanoTime()
+ ((end - start) / (i * 1.0e9), result)
+}
+
+def compile_to_file(bl: Block, class_name: String) : Unit =
+ Using(new java.io.FileWriter(class_name + ".j")) {
+ _.write(compile(bl, class_name))
+ }
+
+def compile_and_run(bl: Block, class_name: String) : Unit = {
+ println(s"Start compilation of $class_name")
+ compile_to_file(bl, class_name)
+ println("generated .j file")
+ (s"java -jar jvm/jasmin-2.4/jasmin.jar ${class_name}.j").!!
+ println("generated .class file ")
+ println("Time: " + time_needed(1, (s"java ${class_name}/${class_name}").!)._1)
+}
+
+
+val arr_test =
+ List(ArrayDef("a", 10), // new(a[10])
+ ArrayDef("b", 2), // new(b[2])
+ AssignA("a", Num(0), Num(10)), // a[0] := 10
+ Assign("x", Ref("a", Num(0))), // x := a[0]
+ Write("x"), // write x
+ AssignA("b", Num(2), Num(5)), // b[2] := 5
+ Assign("x", Ref("b", Num(1))), // x := b[1]
+ Write("x")) // write x
+
+
+compile_and_run(arr_test, "a")
+