Virtual dispatch bug in 292 impl

[Christian Thalinger]

On Dec 17, 2012, at 5:47 PM, Christian Thalinger <christian.thalinger at oracle.com> wrote:

> 
> On Dec 16, 2012, at 11:55 AM, Charles Oliver Nutter <headius at headius.com> wrote:
> 
>> I wasn't sure if this had been filed already by Christian, so I wanted
>> to post here.
>> 
>> It appears that in C1, method handles are not properly dispatching to
>> an overridden version of a method. My reproduction case is tied to
>> JRuby, but I can come up with something isolated if necessary.

I filed:

https://jbs.oracle.com/bugs/browse/JDK-8005418

But it seems to be C2, not C1:

cthaling at sc14ia01:~/jruby$ jruby -J-showversion -J-client test_env.rb 
java version "1.8.0-ea"
Java(TM) SE Runtime Environment (build 1.8.0-ea-b69)
Java HotSpot(TM) Client VM (build 25.0-b13, mixed mode)

Run options: 

# Running tests:

.

Finished tests in 53.285000s, 0.0188 tests/s, 1876.7008 assertions/s.

1 tests, 100000 assertions, 0 failures, 0 errors, 0 skips
cthaling at sc14ia01:~/jruby$ jruby -J-showversion -J-server -J-XX:-TieredCompilation test_env.rb 
java version "1.8.0-ea"
Java(TM) SE Runtime Environment (build 1.8.0-ea-b69)
Java HotSpot(TM) Server VM (build 25.0-b13, mixed mode)

Run options: 

# Running tests:

F

Finished tests in 2.222000s, 0.4500 tests/s, 424.8425 assertions/s.

  1) Failure:
test_bracket(TestEnv) [test_env.rb:11]:
TypeError expected but nothing was raised.

1 tests, 944 assertions, 1 failures, 0 errors, 0 skips
cthaling at sc14ia01:~/jruby$ jruby -J-showversion -J-server -J-XX:+TieredCompilation -J-XX:TieredStopAtLevel=3 test_env.rb 
java version "1.8.0-ea"
Java(TM) SE Runtime Environment (build 1.8.0-ea-b69)
Java HotSpot(TM) Server VM (build 25.0-b13, mixed mode)

Run options: 

# Running tests:

.

Finished tests in 90.676000s, 0.0110 tests/s, 1102.8277 assertions/s.

1 tests, 100000 assertions, 0 failures, 0 errors, 0 skips

-- Chris

>> 
>> In JRuby, the ENV object is a subclass of a Ruby Hash. Rather than
>> rebinding all of Hash's methods (defined on org.jruby.RubyHash), the
>> ENV impl just overrides them at the Java level. When dispatching to
>> the [] method on ENV with invokedynamic, the handle points at
>> RubyHash.op_aref, the implementation of [] for Hash. The ENV version
>> should raise an error...but it does not, because it dispatches to the
>> superclass version rather than the subclass version.
>> 
>> If I turn off tiered compilation, the code works as expected.
>> 
>> Reproduction for JRuby is here: https://gist.github.com/4311979
>> 
>> I tested on hotspot-comp built yesterday:
>> 
>> openjdk version "1.8.0-internal"
>> OpenJDK Runtime Environment (build 1.8.0-internal-headius_2012_12_15_16_45-b00)
>> OpenJDK 64-Bit Server VM (build 25.0-b13, mixed mode)
>> 
>> If I have time I'll try to investigate in more depth.
> 
> This is really odd.  I've fixed a similar bug some time ago:
> 
> https://jbs.oracle.com/bugs/browse/JDK-8000821
> http://bugs.sun.com/view_bug.do?bug_id=8000821
> 
> And there is currently a bug with Nashorn that sounds like the same issue.
> 
> Is it intermittent?  Are you able to reproduce with TieredStopAtLevel=1?
> 
> -- Chris
> 
>> 
>> - Charlie
>