RFR: 8274632: Possible pointer overflow in PretouchTask chunk claiming [v2]

[Albert Mingkun Yang]

On Fri, 1 Oct 2021 20:01:33 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Please review this change to PretouchTask, fixing the mechanism used to
>> claim chunks for parallel touching.  The old mechanism unconditionally added
>> a potentially large value to the current pointer and then checked the result
>> for overflow.  But since pointer arithmetic overflow is UB, that's not a
>> reliable approach.
>> 
>> Testing:
>> mach5 tier1
>
> Kim Barrett has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove unused _start_addr

Using `<newline> + if` instead of `else if` makes the early-return more visible, IMO.

-------------

Marked as reviewed by ayang (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/5791