Re: [Jamvm-general] Can JamVM optimize away static branches?

[Xerxes R. <xe...@za...>]

I have attached a slightly more interesting testcase.
This time the logic gets passed to JamVM.

Can JamVM optimize away these static branches when the public static final are set at runtime?

Cheers
Xerxes

xranby@xranby-ESPRIMO-P7935:~$ cat foo.java
public class foo {
    public static boolean isDebug(){
		String value = System.getProperty("debug");
		if(value!=null)
			return true;
		return false;
    }

    public static final boolean DEBUG=isDebug();

    public static void main(String[] args) {
	foo f = new foo();

	if (f.DEBUG) {
             System.out.print("I have a message to the user, ");
        }

        System.out.print("hello");

        if (f.DEBUG) {
             System.out.print(", i love you all,");
        }

	System.out.println(" world");
    }
}


xranby@xranby-ESPRIMO-P7935:~$ java foo
hello world
xranby@xranby-ESPRIMO-P7935:~$ java -Ddebug foo
I have a message to the user, hello, i love you all, world

xranby@xranby-ESPRIMO-P7935:~$ javap -c foo
Compiled from "foo.java"
public class foo extends java.lang.Object{
public static final boolean DEBUG;

public foo();
  Code:
   0:	aload_0
   1:	invokespecial	#1; //Method java/lang/Object."<init>":()V
   4:	return

public static boolean isDebug();
  Code:
   0:	ldc	#2; //String debug
   2:	invokestatic	#3; //Method java/lang/System.getProperty:(Ljava/lang/String;)Ljava/lang/String;
   5:	astore_0
   6:	aload_0
   7:	ifnull	12
   10:	iconst_1
   11:	ireturn
   12:	iconst_0
   13:	ireturn

public static void main(java.lang.String[]);
  Code:
   0:	new	#4; //class foo
   3:	dup
   4:	invokespecial	#5; //Method "<init>":()V
   7:	astore_1
   8:	aload_1
   9:	pop
   10:	getstatic	#6; //Field DEBUG:Z
   13:	ifeq	24
   16:	getstatic	#7; //Field java/lang/System.out:Ljava/io/PrintStream;
   19:	ldc	#8; //String I have a message to the user,
   21:	invokevirtual	#9; //Method java/io/PrintStream.print:(Ljava/lang/String;)V
   24:	getstatic	#7; //Field java/lang/System.out:Ljava/io/PrintStream;
   27:	ldc	#10; //String hello
   29:	invokevirtual	#9; //Method java/io/PrintStream.print:(Ljava/lang/String;)V
   32:	aload_1
   33:	pop
   34:	getstatic	#6; //Field DEBUG:Z
   37:	ifeq	48
   40:	getstatic	#7; //Field java/lang/System.out:Ljava/io/PrintStream;
   43:	ldc	#11; //String , i love you all,
   45:	invokevirtual	#9; //Method java/io/PrintStream.print:(Ljava/lang/String;)V
   48:	getstatic	#7; //Field java/lang/System.out:Ljava/io/PrintStream;
   51:	ldc	#12; //String  world
   53:	invokevirtual	#13; //Method java/io/PrintStream.println:(Ljava/lang/String;)V
   56:	return

static {};
  Code:
   0:	invokestatic	#14; //Method isDebug:()Z
   3:	putstatic	#6; //Field DEBUG:Z
   6:	return

}