RFR: Refactor heap verification

[Zhengyu Gu]

On 06/01/2017 04:44 PM, Aleksey Shipilev wrote:
> On 06/01/2017 10:41 PM, Zhengyu Gu wrote:
>> Is this right?
>>
>>  239   if (ShenandoahVerify) {
>>  240     ReservedSpace verify_bitmap(_bitmap_size, page_size);
>>  241     os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(),
>> false,
>>  242                               "couldn't allocate verification bitmap");
>>  243     MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
>>  244     MemRegion verify_bitmap_region = MemRegion((HeapWord *)
>> verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
>>  245     _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
>>  246   }
>>  247
>>  248   _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
>>  249
>>
>> You want to construct _verifier without initialized bitmap?
>
> Verifier would barf when used without ShenandoahVerify enabled. And this saves
> NULL-checking on every verifier()->foo() call. Seems like the lesser evil,
> although we need to think if we just want to initialize verification bitmap
> unconditionally, because sometimes Universe asks us to verify anyway.

Well, it can barf in SH::verifier() method, and save the checking inside 
verifier.

-Zhengyu


>
> -Aleksey
>