RFR (XXS): 8057799: G1: unnecessary null check in G1KeepAliveClosure

[Tony Printezis]

Hi Stefan,

Inline.

On 9/9/14, 5:03 AM, Stefan Karlsson wrote:
> Hi Tony,
>
> On 2014-09-08 17:29, Tony Printezis wrote:
>> (following a quick e-mail exchange with Thomas)
>>
>> Here's a small change to remove an unnecessary NULL check from 
>> G1KeepAliveClosure:
>>
>> http://cr.openjdk.java.net/~tonyp/8057799/webrev.0/
>
> Looks good.

Thanks.

> I had to verify that G1StringDedup doesn't assert with this change.

If it does, it would have asserted with the original code too, given 
that _g1->in_cset_state(obj) is called before the null check.

> There's no explicit null-check in the code, but we don't set the oops 
> to NULL G1StringDedupTable.
>
> A side-note: I think this call to JNIHandles::weak_oops_do(&is_alive, 
> &keep_alive) is not needed, since it's already cleaned during the 
> reference processing:
> void ReferenceProcessor::process_phaseJNI(BoolObjectClosure* is_alive,
>                                           OopClosure* keep_alive,
>                                           VoidClosure* complete_gc) {
> ...
>   JNIHandles::weak_oops_do(is_alive, keep_alive);
>   complete_gc->do_void();
> }

Yeah, I added a print statement in weak_oops_do() and I can confirm that.

Tony

> thanks,
> StefanK
>
>>
>> If I could get a couple of reviews and a volunteer to sponsor this, 
>> it'd be awesome. :-)
>>
>> Thanks,
>>
>> Tony
>>
>

-- 
Tony Printezis | JVM/GC Engineer / VM Team | Twitter

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