why gcj is slower than jvm

[guw]

Hello!
	I write a JAVA programme and compile it with GCJ. then I compare GCJ's performance with JVM'performance,but I discover that the procedure to be GCJ compiled is slower than JVM.
  why?

thanks.

===============================================================================
Output data:
JVM:
SHA1: Hashing 100000 blocks of 500 bytes each: time = 5.276, speed = 9254.762 KB/s
MD5: Hashing 100000 blocks of 500 bytes each: time = 3.578, speed = 13646.765 KB/s

GCJ:
SHA1: Hashing 100000 blocks of 500 bytes each: time = 8.719, speed = 5600.1978 KB/s
MD5: Hashing 100000 blocks of 500 bytes each: time = 14.337, speed = 3405.7422 KB/s

===============================================================================
Compiled command:
gcj -O2 --main=HashSpeed HashSpeed.class -o HashSpeed.exe



===============================================================================	
Source code:

import java.security.MessageDigest;
import java.util.Iterator;

public class HashSpeed {

	public static void main(String[] args) {
		 if (args == null || args.length == 0) {
			speed("SHA-1");
		 }
		 else{
		 	int i=0;
			while(i<args.length){
				speed(args[i++]);	
			}					
		 }		 
	  }

	  private static void speed(String name) {
		 try {
			MessageDigest hash = MessageDigest.getInstance(name);
			speed(hash);
		 } catch (Exception x) {
			System.out.println(name+": Failed self-test...:"+x.getLocalizedMessage());
		 }
	  }

	  private static void speed(MessageDigest hash) {
		 try {
			int iterations = 100000;
			int blocksize = 500;
			byte[] data = new byte[blocksize];
			int i;
			for (i = 0; i < blocksize; i++) {
			   data[i] = (byte) i;
			}

			System.out.print(hash.getAlgorithm()+": Hashing "+String.valueOf(iterations)
				  +" blocks of "+String.valueOf(blocksize)+" bytes each: ");
			long elapsed = -System.currentTimeMillis();
			for (i = 0; i < iterations; i++) {
			   hash.update(data, 0, blocksize);
			}
			elapsed += System.currentTimeMillis();
			float secs = (elapsed > 1) ? (float) elapsed / 1000 : 1;
			float speed = (float) iterations * blocksize / 1024 / secs;

			System.out.println("time = "+secs+", speed = "+speed+" KB/s");
		 } catch (Exception x) {
			x.printStackTrace(System.err);
		 }
	  }
}

archer
guw@koal.com

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