diff -r f0696713177b -r 31a9f89776a3 progs/while/compile.sc --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/progs/while/compile.sc Mon Oct 26 10:24:59 2020 +0000 @@ -0,0 +1,258 @@ +// A Small Compiler for the WHILE Language +// (it does not use a parser nor lexer) +// +// cal with +// +// amm compile.sc test +// amm compile.sc test2 + + +// 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 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 +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 + +// 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 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 + invokevirtual java/io/PrintStream/println(I)V + return +.end method + +.method public static read()I + .limit locals 10 + .limit stack 10 + + ldc 0 + istore 1 ; this will hold our final integer +Label1: + getstatic java/lang/System/in Ljava/io/InputStream; + invokevirtual java/io/InputStream/read()I + istore 2 + iload 2 + ldc 10 ; the newline delimiter + isub + ifeq Label2 + iload 2 + ldc 32 ; the space delimiter + isub + ifeq Label2 + + iload 2 + ldc 48 ; we have our digit in ASCII, have to subtract it from 48 + isub + ldc 10 + iload 1 + imul + iadd + istore 1 + goto Label1 +Label2: + ;when we come here we have our integer computed in local variable 1 + iload 1 + ireturn +.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 +""" + +// Compiler functions + + +// for generating new labels +var counter = -1 + +def Fresh(x: String) = { + counter += 1 + x ++ "_" ++ counter.toString() +} + +// 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" +} + +// this allows us to write things like +// i"add" and l"Label" + + +// environments +type Env = Map[String, Int] + + +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)} \t\t; $s" + case Aop(op, a1, a2) => + compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ compile_op(op) +} + +// boolean expression compilation +// - the jump-label is for where to jump if the condition is not true +def compile_bexp(b: BExp, env : Env, jmp: String) : String = b match { + case True => "" + case False => i"goto $jmp" + case Bop("==", a1, a2) => + compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"if_icmpne $jmp" + case Bop("!=", a1, a2) => + compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"if_icmpeq $jmp" + case Bop("<", a1, a2) => + compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"if_icmpge $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; $x", env + (x -> index)) + } +} + +// compilation of a block (i.e. list of instructions) +def compile_block(bl: Block, env: Env) : (String, Env) = bl match { + case Nil => ("", env) + case s::bl => { + val (instrs1, env1) = compile_stmt(s, env) + val (instrs2, env2) = compile_block(bl, env1) + (instrs1 ++ instrs2, env2) + } +} + +// main compilation function for blocks +def compile(bl: Block, class_name: String) : String = { + val instructions = compile_block(bl, Map.empty)._1 + (beginning ++ instructions ++ ending).replaceAllLiterally("XXX", class_name) +} + + + + + +// Fibonacci numbers as a bare-bone test-case +val fib_test = + List(Assign("n", Num(9)), // n := 10; + Assign("minus1",Num(0)), // minus1 := 0; + Assign("minus2",Num(1)), // minus2 := 1; + Assign("temp",Num(0)), // temp := 0; + While(Bop("<",Num(0),Var("n")), // while n > 0 do { + List(Assign("temp",Var("minus2")), // temp := minus2; + Assign("minus2",Aop("+",Var("minus1"),Var("minus2"))), + // minus2 := minus1 + minus2; + Assign("minus1",Var("temp")), // minus1 := temp; + Assign("n",Aop("-",Var("n"),Num(1))))), // n := n - 1 }; + Write("minus1")) // write minus1 + + + +// prints out the JVM instructions +@main +def test() = + println(compile(fib_test, "fib")) + + + + +// compiling and running .j-files +// +// JVM files can be assembled with +// +// java -jar jasmin.jar fib.j +// +// and started with +// +// java fib/fib + + +def run(bl: Block, class_name: String) = { + val code = compile(bl, class_name) + os.write.over(os.pwd / s"$class_name.j", code) + os.proc("java", "-jar", "jasmin.jar", s"$class_name.j").call() + print(os.proc("java", s"$class_name/$class_name").call().out.string) +} + +@main +def test2() = + run(fib_test, "fib")