FULL PRODUCT VERSION :
java version "1.6.0-beta2"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-beta2-b72)
Java HotSpot(TM) Client VM (build 1.6.0-beta2-b72, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux cehost 2.6.15-1.1831_FC4 #1 Tue Feb 7 13:37:42 EST 2006 i686 i686 i386 GNU/Linux

EXTRA RELEVANT SYSTEM CONFIGURATION :
Pentium4 Northwood, 2.6ghz

A DESCRIPTION OF THE PROBLEM :
I use some encryption code in my application and just for interest I thought benchmarking it would be quite interesting. The code was ported from C (not by me) and performs quite poor on hotspot.
Please don't comment on code-quality, it is just an example where code generated by hotspot does not perform as well as it could.

Here are some numbers for the original version:
IBM 1.4.2: 2.29874488529263mb/s
Hotspot 1.3.1 Server: 1.6164489848700376mb/s
Hotspot 6.0b72 Server: 1.5088873464707124mb/s

Numbers for the tuned Version:
Hotspot 1.3.1 Server: 2.9244896765514414mb/s
Hotspot 6.0b72 Server: 2.7785495971103082mb/s
IBM 1.4.2: 2.7506312220847015mb/s

Both times the Hotspot 1.3.1 Server compiler produces faster code, thats why I marked it as regression.
The main problem seems to be the access to member-variables inside of code(), IBM can optimize this quite well whereas Hotspot has some troubles with the code.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the sample-code attached with the server compiler.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Mustang's c2 should at least be faster than 1.3.1's hotspot server compiler.
ACTUAL -
6.0b72 is always slower than 1.3.1, IBM seems to handle member-field access much better on P4.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
1.) Not tuned version:
-----------------------------------------------------------------------
/* PORTED TO JAVA BY ROBERT NEILD November 1999 */

/* PC1 Cipher Algorithm ( Pukall Cipher 1 ) */
/* By Alexander PUKALL 1991 */
/* free code no restriction to use */
/* please include the name of the Author in the final software */
/* the Key is 128 bits */

/* Only the K zone change in the two routines */
/* You can create a single routine with the two parts in it */

public class PC1_Stream
{
int ax, bx, cx, dx, si, tmp, x1a2, res, i, inter, cfc, cfd, compte;
int x1a0[] = new int[8];
byte cle[] = new byte[17]; // Hold key
private boolean usedAsEncrypter = false;
private boolean alreadyUsed = false;

/**
* Creates a PC1_InputStream. Decodes an input stream of encoded data.
* @param in The input stream to decode.
* @param password 16 byte encryption key
*/

public PC1_Stream(byte[] password)
{
System.arraycopy(password, 0, cle, 0, Math.min(16, password.length));
}

private void assemble()
{
x1a0[0] = ((cle[0] * 256) + cle[1]);

code();
inter = res;

x1a0[1] = (x1a0[0] ^ ((cle[2] * 256) + cle[3]));
code();
inter = (inter ^ res);

x1a0[2] = (x1a0[1] ^ ((cle[4] * 256) + cle[5]));
code();
inter = (inter ^ res);

x1a0[3] = (x1a0[2] ^ ((cle[6] * 256) + cle[7]));
code();
inter = (inter ^ res);

x1a0[4] = (x1a0[3] ^ ((cle[8] * 256) + cle[9]));
code();
inter = (inter ^ res);

x1a0[5] = (x1a0[4] ^ ((cle[10] * 256) + cle[11]));
code();
inter = (inter ^ res);

x1a0[6] = (x1a0[5] ^ ((cle[12] * 256) + cle[13]));
code();
inter = (inter ^ res);

x1a0[7] = (x1a0[6] ^ ((cle[14] * 256) + cle[15]));
code();
inter = (inter ^ res);

i = 0;
}

void code()
{
dx = (x1a2 + i);
ax = x1a0[i];

cx = 0x015a;
bx = 0x4e35;

tmp = ax;
ax = si;
si = tmp;

tmp = ax;
ax = dx;
dx = tmp;

if (ax != 0)
{
ax = (ax * bx);
}

tmp = ax;
ax = cx;
cx = tmp;

if (ax != 0)
{
ax = (ax * si);
cx = (ax + cx);
}

tmp = ax;
ax = si;
si = tmp;
ax = (ax * bx);
dx = (cx + dx);

ax = (ax + 1);

x1a2 = dx;
x1a0[i] = ax;

res = (ax ^ dx);
i = (i + 1);
}

/**
* Returns a plain byte, which has been unencrypted from the underlying
* InputStream.
* @see java.io.FilterInputStream
*/

public byte[] decrypt(byte[] encryptedData)
{
checkUsage(false);

for (int i = 0; i < encryptedData.length; i++)
{
int c = encryptedData[i];

assemble();
cfc = (inter >> 8);
cfd = (inter & 255);

c = c ^ (cfc ^ cfd);

for (compte = 0; compte <= 15; compte++)
{
/* we mix the plaintext byte with the key */
cle[compte] = (byte) (cle[compte] ^ c);
}

encryptedData[i] = (byte) c;
}

return encryptedData;
}

public byte[] encrypt(byte[] data)
{
checkUsage(true);

for (int i = 0; i < data.length; i++)
{
int c = data[i];

assemble();
cfc = (inter >> 8);
cfd = (inter & 255);

for (compte = 0; compte <= 15; compte++)
{
/* we mix the plaintext byte with the key */
cle[compte] = (byte) (cle[compte] ^ c);
}

c = c ^ (cfc ^ cfd);
data[i] = (byte) c;
}

return data;
}

private void checkUsage(boolean isEncrypter)
{
if (alreadyUsed)
{
if (usedAsEncrypter != isEncrypter)
{
throw new IllegalArgumentException("You may either use this class as encrypter or decrypter, not both!");
}
} else
{
alreadyUsed = true;
usedAsEncrypter = isEncrypter;
}
}

public static void main(String[] args)
{
byte[] testData = new byte[1024 * 1024];
for (int i = 0; i < testData.length; i++)
{
testData[i] = (byte) (i % 127);
}

PC1_Stream dec = new PC1_Stream(testData);
PC1_Stream enc = new PC1_Stream(testData);

for (int i = 0; i < 5; i++)
{
enc.encrypt(testData);
dec.decrypt(testData);
}

for (int m = 0; m < 10; m++)
{
int encCount = 50;
System.out.println("Starte Verschlüsselung");
long start = System.currentTimeMillis();
for (int i = 0; i < encCount; i++)
{
enc.encrypt(testData);
dec.decrypt(testData);
}
long end = System.currentTimeMillis();
long duration = end - start;
System.out.println("Encryption took: " + duration + " with " + ((double) encCount / ((double) duration / (double) 1000)) + "mb/s ");
}
}
}
------------------------------------------------------------------------------

2.) Slightly tuned version:
-----------------------------------------------------------------------------
public class PC1_Stream_tuned
{
int si, x1a2;
int x1a0[] = new int[8];
byte cle[] = new byte[17]; // Hold key
private boolean usedAsEncrypter = false;
private boolean alreadyUsed = false;

/**
* Creates a PC1_InputStream. Decodes an input stream of encoded data.
* @param in The input stream to decode.
* @param password 16 byte encryption key
*/

public PC1_Stream_tuned(byte[] password)
{
System.arraycopy(password, 0, cle, 0, Math.min(16, password.length));
}

private int assemble()
{
x1a0[0] = ((cle[0] * 256) + cle[1]);

int inter = code(0);

x1a0[1] = (x1a0[0] ^ ((cle[2] * 256) + cle[3]));
inter = inter ^ code(1);

x1a0[2] = (x1a0[1] ^ ((cle[4] * 256) + cle[5]));
inter = inter ^ code(2);

x1a0[3] = (x1a0[2] ^ ((cle[6] * 256) + cle[7]));
inter = inter ^ code(3);

x1a0[4] = (x1a0[3] ^ ((cle[8] * 256) + cle[9]));
inter = inter ^ code(4);

x1a0[5] = (x1a0[4] ^ ((cle[10] * 256) + cle[11]));
inter = inter ^ code(5);

x1a0[6] = (x1a0[5] ^ ((cle[12] * 256) + cle[13]));
inter = inter ^ code(6);

x1a0[7] = (x1a0[6] ^ ((cle[14] * 256) + cle[15]));
inter = inter ^ code(7);

return inter;
}

protected int code(final int i)
{
int ax = x1a0[i];
int dx = (x1a2 + i);
int cx = 0x015a;
int tmp;
final int bx = 0x4e35;

tmp = ax;
ax = si;
si = tmp;

tmp = ax;
ax = dx;
dx = tmp;

if (ax != 0)
{
ax = (ax * bx);
}

tmp = ax;
ax = cx;
cx = tmp;

if (ax != 0)
{
ax = (ax * si);
cx = (ax + cx);
}

tmp = ax;
ax = si;
si = tmp;

ax = (ax * bx);
dx = (cx + dx);
ax++;

x1a2 = dx;
x1a0[i] = ax;

return (ax ^ dx);
}

/**
* Returns a plain byte, which has been unencrypted from the underlying
* InputStream.
* @see java.io.FilterInputStream
*/

public byte[] decrypt(byte[] encryptedData)
{
checkUsage(false);

for (int i = 0; i < encryptedData.length; i++)
{
int c = encryptedData[i];

int inter = assemble();
int cfc = (inter >> 8);
int cfd = (inter & 255);

c = c ^ (cfc ^ cfd);

for (int compte = 0; compte <= 15; compte++)
{
/* we mix the plaintext byte with the key */
cle[compte] = (byte) (cle[compte] ^ c);
}

encryptedData[i] = (byte) c;
}

return encryptedData;
}

public byte[] encrypt(byte[] data)
{
checkUsage(true);

for (int i = 0; i < data.length; i++)
{
int c = data[i];

int inter = assemble();
int cfc = (inter >> 8);
int cfd = (inter & 255);

for (int compte = 0; compte <= 15; compte++)
{
/* we mix the plaintext byte with the key */
cle[compte] = (byte) (cle[compte] ^ c);
}

c = c ^ (cfc ^ cfd);
data[i] = (byte) c;
}

return data;
}

private void checkUsage(boolean isEncrypter)
{
if (alreadyUsed)
{
if (usedAsEncrypter != isEncrypter)
{
throw new IllegalArgumentException("You may either use this class as encrypter or decrypter, not both!");
}
} else
{
alreadyUsed = true;
usedAsEncrypter = isEncrypter;
}
}

public static void main(String[] args)
{
byte[] testData = new byte[1024 * 1024];
for (int i = 0; i < testData.length; i++)
{
testData[i] = (byte) (i % 127);
}

PC1_Stream_tuned dec = new PC1_Stream_tuned(testData);
PC1_Stream_tuned enc = new PC1_Stream_tuned(testData);

for (int i = 0; i < 5; i++)
{
enc.encrypt(testData);
dec.decrypt(testData);
}

for (int m = 0; m < 10; m++)
{
int encCount = 50;
System.out.println("Starte Verschlüsselung");
long start = System.currentTimeMillis();
for (int i = 0; i < encCount; i++)
{
enc.encrypt(testData);
dec.decrypt(testData);
}
long end = System.currentTimeMillis();
long duration = end - start;
System.out.println("Encryption took: " + duration + " with " + ((double) encCount / ((double) duration / (double) 1000)) + "mb/s ");
}
}
}


---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
use IBM Jvm, try to not access member-variables too often.

Release Regression From : 1.3.1
The above release value was the last known release where this
bug was known to work. Since then there has been a regression.