RFR: 8253889: Remove ExecMem constant

[Thomas Stüfe]

Thank you David! I will remove the PR.

On Tue, Oct 6, 2020 at 9:35 AM David Holmes <dholmes at openjdk.java.net>
wrote:

> On Sat, 3 Oct 2020 05:30:54 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:
>
> >>> Maybe it did something in the past. Now it just seems to be a
> complicated way to say "false".
> >>
> >> I think that's a Hotspot style. There are few other places where
> "symbolic values" for boolean parameters are used. For
> >> example, `CodeBlobToOopClosure::FixRelocations`. `grep 'static const
> bool'` identify a few more. I personally find it a
> >> tad more readable. So, it is not as useless...
> >
> >> > Maybe it did something in the past. Now it just seems to be a
> complicated way to say "false".
> >>
> >> I think that's a Hotspot style. There are few other places where
> "symbolic values" for boolean parameters are used. For
> >> example, `CodeBlobToOopClosure::FixRelocations`. `grep 'static const
> bool'` identify a few more. I personally find it a
> >> tad more readable. So, it is not as useless...
> >
> > Well in that case it is applied very inconsistently since most call
> sites just use false. Lets see if anyone else has
> > an opinion on this.
>
> It is a way of documenting the boolean more clearly. This example was
> introduced by JDK-8013057. In the RFR:
>
>
> http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2013-June/007617.html
>
> Dan writes:
>
> > As a secondary change, while visiting all os::commit_memory() calls, I
> also updated them to use the new ExecMem enum in
> > order to make the executable status of the memory more clear. Since
> executable memory can be an attack vector, it is
> > prudent to make the executable status of memory crystal clear. This also
> allowed me to remove the default executable
> > flag value of 'false'. Now all new uses of commit_memory() must be clear
> about the executable status of the memory.
>
> So IMO this is not something that needs changing.
>
> Thanks,
> David
>
> -------------
>
> PR: https://git.openjdk.java.net/jdk/pull/454
>