RFR (S) [8u] 8155635: C2: Mixed unsafe oop accesses break alias analysis
vladimir.kozlov at oracle.com
Sat Oct 20 01:17:07 UTC 2018
Yes, leaving comment will be good but you need to use @comment command for that. Otherwise it is treated as continuation
of previous line. Or add comment in a separate comment block if jtreg for jdk8 does not support @comment.
On 10/19/18 6:01 PM, David Buck wrote:
> Hi Vladimir!
> Thanks for taking a look at this.
> > And I did not find in Bug or Review
> > that it is G1 specific problem.
> Yeah, I'm confident that it is not G1-specific, but I failed in coming up with an easy way to reproduce the issue
> without G1. Only after a frustrated afternoon of trying to get the testcase to reproduce on JDK 8 did I stumble on
> Mikael's comment (2014-08-26 20:58) in JDK-8056058  that G1 seemed to help trigger the issue.
> > Specifying GC in test is 'no-no'. You can have conflict when testing
> > environment pass different GC flag.
> I did not know about this rule. Thanks for catching this. How about, after removing the flag from the command line, I
> add a comment saying that running with G1 seems to help trigger the issue? Something like this perhaps?
> * @test
> * @bug 8155635
> * @library /testlibrary
> * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -Xbatch -XX:-TieredCompilation
> * @run main/othervm -Xbatch compiler.unsafe.MixedUnsafeStoreObject
> * Testcase currently only known to reproduce when run with -XX:+UseG1GC.
> BTW, this seems true for JDK 9 as well. For example, specifying UseParallelGC or UseConcMarkSweepGC with JDK 9 makes the
> testcase pass.
>  https://bugs.openjdk.java.net/browse/JDK-8056058
> On 2018/10/20 2:01, Vladimir Kozlov wrote:
>> Specifying GC in test is 'no-no'. You can have conflict when testing environment pass different GC flag. And I did not
>> find in Bug or Review that it is G1 specific problem.
>> Otherwise looks good.
>> On 10/19/18 1:15 AM, David Buck wrote:
>>> May I please get a review of this straightforward backport:
>>> bug report:
>>> JDK 9 code review thread:
>>> JDK 9 changeset:
>>> JDK 8 webrev (for review):
>>> The only minor differences from the JDK 9 fix are the different assert message formatting  and the following
>>> changes to the testcase:
>>> - use of com.oracle.java.testlibrary.Utils to get Unsafe
>>> - addition of -XX:+UseG1GC to command line (this is default in JDK 9, so explicit flag was not needed)
>>>  https://bugs.openjdk.java.net/browse/JDK-8080775
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