Assembly Language for Beginners

4.1. JAVA

public static long lclear (long a, int b)

{

return a & (~(1<<b));

}

public static long lset(long, int);

flags: ACC_PUBLIC, ACC_STATIC

Code:

stack=4, locals=3, args_size=2

0: lload_0

1: iconst_1

2: iload_2

3: ishl

4: i2l

5: lor

6: lreturn

public static long lclear(long, int);

flags: ACC_PUBLIC, ACC_STATIC

Code:

stack=4, locals=3, args_size=2

0: lload_0

1: iconst_1

2: iload_2

3: ishl

4: iconst_m1

5: ixor

6: i2l

7: land

8: lreturn

The code is the same, but instructions withlprefix are used, which operate on 64-bit values.

Also, the second argument of the function still is of typeint, and when the 32-bit value in it needs to be
promoted to 64-bit value thei2linstruction is used, which essentially extend the value of anintegertype
to alongone.

4.1.11 Loops

public class Loop
{
public static void main(String[] args)
{
for (int i = 1; i <= 10; i++)
{
System.out.println(i);
}
}
}

public static void main(java.lang.String[]);

flags: ACC_PUBLIC, ACC_STATIC

Code:

stack=2, locals=2, args_size=1

0: iconst_1

1: istore_1

2: iload_1

3: bipush 10

5: if_icmpgt 21

8: getstatic #2 // Field java/lang/System.out:Ljava/io/PrintStream;

11: iload_1

12: invokevirtual #3 // Method java/io/PrintStream.println:(I)V

15: iinc 1, 1

18: goto 2

21: return

iconst_1loads 1 intoTOS,istore_1stores it in theLVAat slot 1.