Request for reviews (XS): 6869822: assert(Universe::narrow_oop_shift() == 0,"use unscaled narrow oop")

[Vladimir Kozlov]

Thanks, Tom

Vladimir

Tom Rodriguez wrote:
> looks good.
> 
> tom
> 
> On Aug 11, 2009, at 9:23 AM, Vladimir Kozlov wrote:
> 
>>
>> http://cr.openjdk.java.net/~kvn/6869822/webrev.00
>>
>> Fixed 6869822: assert(Universe::narrow_oop_shift() == 0,"use unscaled 
>> narrow oop")
>>
>> Problem:
>> The test uses -XX:HeapBaseMinAddress=32g flag to force heap allocation
>> above 32g and get compressed oops with non zero base.
>> In such case the finction Universe::preferred_heap_base() sets
>> narrow_oop_shift to 3 and returns 0 as requested heap address.
>> But with 0 requested address (default memory address request) OS still 
>> may
>> allocate small heap bellow 4gb. And this will trigger the assert.
>>
>> Solution:
>> Replace the assert with narrow_oop_shift set to 0.
>> Also use specified on command line HeapBaseMinAddress value as
>> heap base address for the first (from three) request.
>>
>> Reviewed by:
>>
>> Fix verified (y/n): y, bug's tests
>>
>> Other testing:
>> JPRT
>>
>