RFR (7xS): 8177044: Remove _scan_top from HeapRegion

[sangheon]

Hi Thomas,

On 05/11/2017 07:18 AM, Thomas Schatzl wrote:
> Hi Kim and Sangheon,
>
> On Tue, 2017-05-09 at 11:12 -0700, sangheon wrote:
>> Hi Thomas,
>>
>> On 05/05/2017 05:13 AM, Thomas Schatzl wrote:
>>> Hi all,
>>>
>>>     recent reviews have made changes necessary to parts of the
>>> changeset
>>> chain.
>>>
>>> Here is a list of links to updated webrevs. Since they have
>>> apparently
>>> not been reviewed yet, I simply overwrote the old webrevs.
>>>
>>> JDK-8177044: Remove _scan_top from HeapRegion
>>> http://cr.openjdk.java.net/~tschatzl/8177044/webrev/
>> Looks good to me.
>> And agree to Kim about retaining the comment.
>>
>> src/share/vm/gc/g1/g1RemSet.cpp
>>    765   if (scan_limit <= start) {
>>    766     // If the trimmed region is empty, the card must be stale.
>>    767     return false;
>>
>    thanks for your review.
>
> For reference, here is the comment I intend to push:
>
> --- old/src/share/vm/gc/g1/g1RemSet.cpp	2017-05-11
> 16:14:56.054517736 +0200
> +++ new/src/share/vm/gc/g1/g1RemSet.cpp	2017-05-11
> 16:14:55.951514554 +0200
> @@ -735,6 +735,7 @@
>   
>     HeapWord* scan_limit = _scan_state->scan_top(r->hrm_index());
>     if (scan_limit <= start) {
> +    // If the card starts above the area in the region containing
> objects to scan, skip it.
>       return false;
>     }
>   
> because the original comment is wrong now.
>
> New Webrevs:
> http://cr.openjdk.java.net/~tschatzl/8177044/webrev.0_to_1/ (diff)
> http://cr.openjdk.java.net/~tschatzl/8177044/webrev.1/ (full)
Webrev.1 looks good to me.

Thanks,
Sangheon


>
> Thanks again for your reviews,
>    Thomas
>