// File RTCG3.java --- calling generated methods that contain loops
// sestoft@itu.dk * 2002

// Using the gnu.bytecode package from http://www.gnu.org/software/kawa

// All three generated methods are precisely as fast as the compiled
// Java method.

import gnu.bytecode.*;
import java.io.*;			// IOException

public class RTCG3 {
  public static void main(String[] args) 
    throws IOException, NoSuchMethodException, IllegalAccessException, 
           java.lang.reflect.InvocationTargetException {
    int count = Integer.parseInt(args[0]);
    ClassType co = new ClassType("MyClass");
    co.setSuper("java.lang.Object");
    co.setModifiers(Access.PUBLIC);
    {
      // Build: public static void MyMethod1(int x) { ... }
      Method mo = co.addMethod("MyMethod1");
      mo.setSignature("(I)V");
      mo.setModifiers(Access.PUBLIC | Access.STATIC);
      mo.initCode();
      // Obtain a JVM code generator jvmg
      CodeAttr jvmg = mo.getCode();
      Scope scope = mo.pushScope();
      Variable lvar0 = scope.addVariable(jvmg, Type.int_type, "x");
      Label start = new Label(jvmg);
      start.define(jvmg);
      jvmg.emitLoad(lvar0);
      jvmg.emitPushInt(1);
      jvmg.emitSub('I'); 
      jvmg.emitStore(lvar0);
      jvmg.emitLoad(lvar0);
      jvmg.emitPushInt(0);
      jvmg.emitGotoIfGt(start);
      mo.popScope();
      jvmg.emitReturn();
    }
    {
      // Build: public static void MyMethod2(int x) { ... }
      Method mo = co.addMethod("MyMethod2");
      mo.setSignature("(I)V");
      mo.setModifiers(Access.PUBLIC | Access.STATIC);
      mo.initCode();
      // Obtain a JVM code generator jvmg
      CodeAttr jvmg = mo.getCode();
      Scope scope = mo.pushScope();
      Variable lvar0 = scope.addVariable(jvmg, Type.int_type, "x");
      Label start = new Label(jvmg);
      start.define(jvmg);
      jvmg.emitLoad(lvar0);
      jvmg.emitPushInt(1);
      jvmg.emitSub('I'); 
      jvmg.emitDup();
      jvmg.emitStore(lvar0);
      jvmg.emitPushInt(0);
      jvmg.emitGotoIfGt(start);
      mo.popScope();
      jvmg.emitReturn();
    
    }
    {
      // Build: public static void MyMethod3(int x) { ... }
      Method mo = co.addMethod("MyMethod3");
      mo.setSignature("(I)V");
      mo.setModifiers(Access.PUBLIC | Access.STATIC);
      mo.initCode();
      // Obtain a JVM code generator jvmg
      CodeAttr jvmg = mo.getCode();
      Scope scope = mo.pushScope();
      Variable lvar0 = scope.addVariable(jvmg, Type.int_type, "x");
      Label start = new Label(jvmg);
      start.define(jvmg);
      jvmg.emitInc(lvar0, (short)-1);
      jvmg.emitLoad(lvar0);
      jvmg.emitPushInt(0);
      jvmg.emitGotoIfGt(start);
      mo.popScope();
      jvmg.emitReturn();
    }
    // Output class file to array:
    byte[] classFile = co.writeToArray();
    // Load the class file into the JVM 
    Class ty = new ArrayClassLoader().loadClass("MyClass", classFile);
    {
      java.lang.reflect.Method m = 
	ty.getMethod("MyMethod1", new Class[] { int.class }); 
      Timer t = new Timer();
      m.invoke(null, new Object[] { new Integer(count) });
      System.out.println("Generated method 1: " + t.Check() + " sec");
    }
    {
      java.lang.reflect.Method m = 
	ty.getMethod("MyMethod2", new Class[] { int.class }); 
      Timer t = new Timer();
      m.invoke(null, new Object[] { new Integer(count) });
      System.out.println("Generated method 2: " + t.Check() + " sec");
    }
    {
      java.lang.reflect.Method m = 
	ty.getMethod("MyMethod3", new Class[] { int.class }); 
      Timer t = new Timer();
      m.invoke(null, new Object[] { new Integer(count) });
      System.out.println("Generated method 3: " + t.Check() + " sec");
    }
    {
      Timer t = new Timer();
      YourMethod(count);
      System.out.println("Compiled Java method: " + t.Check() + " sec");
    }
  }

  public static void YourMethod(int n) {
    do { 
      n--;
    } while (n != 0);
  }
}

// This is needed because defineClass is protected in java.lang.ClassLoader:

class ArrayClassLoader extends ClassLoader {
  public Class loadClass(String name, byte[] classFile) {
    return defineClass(name, classFile, 0, classFile.length);
  }
}

// Crude timing utility ----------------------------------------
   
class Timer {
  private long start;

  public Timer() {
    start = System.currentTimeMillis();
  }

  public double Check() {
    return (System.currentTimeMillis()-start)/1000.0;
  }
}