RFR: 8258382: Fix optimization-unstable code involving pointer overflow [v2]

[Kim Barrett]

On Fri, 1 Jan 2021 03:48:25 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Hao Sun has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix unstable code involving pointer overflow only
>>   
>>   Move the patch involving singed integer overflow into another PR.
>>   In this patch we only fix optimization-unstable code involving pointer
>>   overflow.
>>   
>>   Update the patch based on feedback from upstream.
>>   1) Remove unnecessary comment.
>>   2) Remove unnecessary check between end() and top()
>>   3) Use pointer_delta() to compute the offset between two addresses.
>>   
>>   Change-Id: Icade8e1a4b684081036c85fd2a2b65b5c3b27f54
>>   CustomizedGitHooks: yes
>
> Marked as reviewed by kbarrett (Reviewer).

Thanks for splitting up the changes.  The GC changes look good.

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PR: https://git.openjdk.java.net/jdk/pull/1886