Closed
Description
Java -version output
openjdk version "11.0.16-internal" 2022-07-19
OpenJDK Runtime Environment (build 11.0.16-internal+0-adhoc..openj9-openjdk-jdk11)
Eclipse OpenJ9 VM (build master-4ca209b54, JRE 11 Linux amd64-64-Bit Compressed References 20220615_000000 (JIT enabled, AOT enabled)
OpenJ9 - 4ca209b54
OMR - 26b89f9f9
JCL - 231dcc9eeb based on jdk-11.0.16+6)
openjdk version "17.0.4-internal" 2022-07-19
OpenJDK Runtime Environment (build 17.0.4-internal+0-adhoc..openj9-openjdk-jdk17)
Eclipse OpenJ9 VM (build master-79f0b73fa, JRE 17 Linux amd64-64-Bit Compressed References 20220701_000000 (JIT enabled, AOT enabled)
OpenJ9 - 79f0b73fa
OMR - d018241d7
JCL - c6e2f71170b based on jdk-17.0.4+7)
Summary of problem
The following test is a bit tricky. It gives a different result from -Xint. But cannot understand which JIT level causes the test to fail. So it should be different from #15306 (from scorching) and #15347 (from hot).
It affects both JDK11 and JDK17.
class Test {
int N;
long instanceCount;
float fFld;
long vMeth1_check_sum;
void vMeth1() {
if (ax$0) {
String[][] ax$3 = new String[2515][1];
for (String[] ax$5 : ax$3) {}
return;
}
int i2, i3, i5, i6 = 2, i7 = 227;
for (i3 = 6; i3 < 157; ++i3)
for (i5 = 4; i5 > 1; --i5) {
instanceCount = i7;
i6 += i7;
}
vMeth1_check_sum += i6;
}
void vMeth() {
try {
ax$0 = true;
for (int ax$7 = 0; ax$7 < 5913; ax$7 += 1) vMeth1();
} finally {
ax$0 = false;
}
vMeth1();
}
int iMeth() {
long[] lArr = new long[N];
vMeth();
long meth_res = checkSum(lArr);
return (int) meth_res;
}
void mainTest(String[] strArr1) {
fFld -= iMeth();
System.out.println(vMeth1_check_sum);
}
public static void main(String[] strArr) {
Test _instance = new Test();
_instance.mainTest(strArr);
}
public static long checkSum(long[] a) {
long sum = 0;
for (int j = 0; j < a.length; j++) {
sum += (a[j] / (j + 1) + a[j] % (j + 1));
}
return sum;
}
Boolean ax$0;
}Results of OpenJ9-Xint (HotSpot/ART also give the same result):
$ ./OpenJ9/jdk11/java -Xint Test
102833
Results of OpenJ9:
$ ./OpenJ9/jdk11/java Test
34279
Diagnosis
Only two methods in Test are compiled:
$ ./OpenJ9/jdk17/bin/java '-Xjit:verbose' Test 2>&1 | grep Test.
+ (warm) Test.vMeth1()V @ 00007F28659DA3C0-00007F28659DA5F8 OrdinaryMethod - Q_SZ=0 Q_SZI=0 QW=12 j9m=000000000018F488 bcsz=110 GCR compThreadID=0 CpuLoad=18%(2%avg) JvmCpu=0%
+ (profiled very-hot) Test.vMeth1()V @ 00007F28659DA640-00007F28659DA94A OrdinaryMethod 100.00% T Q_SZ=0 Q_SZI=0 QW=100 j9m=000000000018F488 bcsz=110 OSR JPROF compThreadID=0 CpuLoad=18%(2%avg) JvmCpu=0%
+ (scorching) Test.vMeth1()V @ 00007F28659DA9A0-00007F28659DAB8C OrdinaryMethod J Q_SZ=0 Q_SZI=0 QW=100 j9m=000000000018F488 bcsz=110 OSR compThreadID=0 CpuLoad=18%(2%avg) JvmCpu=0%
+ (warm) Test.vMeth()V @ 00007F28659DABE0-00007F28659DAEBC OrdinaryMethod - Q_SZ=0 Q_SZI=0 QW=12 j9m=000000000018F4A8 bcsz=54 GCR compThreadID=0 CpuLoad=18%(2%avg) JvmCpu=0%
+ (hot) Test.vMeth()V @ 00007F28659DA674-00007F28659DA8AF MethodInProgress - Q_SZ=0 Q_SZI=0 QW=1 j9m=000000000018F4A8 bcsz=54 DLT@10 compThreadID=0 CpuLoad=18%(2%avg) JvmCpu=0%
It seems the compilation of Test.vMeth1() causes this failure because if you exclude it the result becomes correct (excluding Test.vMeth() makes no effects):
$ ./OpenJ9/jdk17/bin/java '-Xjit:exclude={Test.vMeth1()V}' Test
102833
$ ./OpenJ9/jdk17/bin/java '-Xjit:exclude={Test.vMeth()V}' Test
34279
But with -Xjit option, no matter which JIT level you try, the bug never reappears:
$ ./OpenJ9/jdk17/bin/java '-Xjit:{Test.vMeth1()V}(optlevel=noopt)' Test
102833
$ ./OpenJ9/jdk17/bin/java '-Xjit:{Test.vMeth1()V}(optlevel=cold)' Test
102833
$ ./OpenJ9/jdk17/bin/java '-Xjit:{Test.vMeth1()V}(optlevel=warm)' Test
102833
$ ./OpenJ9/jdk17/bin/java '-Xjit:{Test.vMeth1()V}(optlevel=hot)' Test
102833
$ ./OpenJ9/jdk17/bin/java '-Xjit:{Test.vMeth1()V}(optlevel=veryhot)' Test
102833
$ ./OpenJ9/jdk17/bin/java '-Xjit:{Test.vMeth1()V}(optlevel=scorching)' Test
102833
As a comparison, 15306 can reproduce its bug from scorching and 15347 from hot. So I guess this is a different new one.