Request for reviews (S): 6826736: CMS: core dump with -XX:+UseCompressedOops

Vladimir Kozlov Vladimir.Kozlov at Sun.COM
Wed Jul 22 13:42:39 PDT 2009


Thank you, John

I will fix comments.

Vladimir

John Coomes wrote:
> Vladimir Kozlov (Vladimir.Kozlov at Sun.COM) wrote:
>> http://cr.openjdk.java.net/~kvn/6826736/webrev.01
>>
>> Fixed 6826736: CMS: core dump with -XX:+UseCompressedOops
>>
>> Problem:
>> Compiled code may produce decoded oop = narrow_oop_base
>> when a narrow oop implicit null check is used.
>> ...
>> Solution:
>> Fix deoptimization code and GC to check for such oops values.
>> During deoptimization convert them to NULL.
>> And ignore them for GC (like NULL values are ignored).
> 
> Looks reasonable to me, but I don't know this code.  Spotted a couple
> of typos:
> 
> 412              // is interesting in NULL.
> 
> Change to interesting to interested.
> 
> 
> 
> 432           assert((*loc) == (oop)NULL || Universe::narrow_oop_base() != (address)(void*)(*loc),
> 433                  "found non valid value pointer");
> 
> Change "non valid" to invalid.
> 
> FWIW, I also like Paul's suggestion of is_narrow_oop_base(void*).
> 
> -John
> 



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