JDK-6973308 : Missing zero length check before repne scas in check_klass_subtype_slow_path()
- Type: Enhancement
- Component: hotspot
- Sub-Component: compiler
- Affected Version: hs12
- Priority: P4
- Status: Closed
- Resolution: Fixed
- OS: solaris_10
- CPU: sparc
- Submitted: 2010-07-29
- Updated: 2011-04-23
- Resolved: 2011-04-23
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| JDK 6 | JDK 7 | Other |
|---|---|---|
| 6u21pFixed | 7Fixed  |
hs19Fixed |
Description
Z flag value will not be set by 'repne' if RCX == 0 since 'repne' does not change flags.
Setting Z = 1 before repne_scanl() in check_klass_subtype_slow_path():
// pointer were to sneak in here. Note that we have already loaded the
// Klass::super_check_offset from the super_klass in the fast path,
// so if there is a null in that register, we are already in the afterlife.
+ push(rax);
+ xorq(rax,rax); // Set Z = 1
+ pop(rax);
repne_scanl();
will cause next exception:
% java -Xmx128M -jar GCBasher.jar -time:300
Exception in thread "main" java.lang.IncompatibleClassChangeError
at java.lang.StringCoding$StringDecoder.decode(StringCoding.java:153)
at java.lang.StringCoding.decode(StringCoding.java:193)
at java.lang.String.<init>(String.java:452)
at java.util.jar.Attributes.read(Attributes.java:418)
at java.util.jar.Manifest.read(Manifest.java:199)
at java.util.jar.Manifest.<init>(Manifest.java:69)
at java.util.jar.JarFile.getManifestFromReference(JarFile.java:177)
at java.util.jar.JarFile.getManifest(JarFile.java:163)
j
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