Propose to use clang-format to enforce hotspot codestyle

[Ioi Lam]

On 3/12/20 2:36 AM, Andrew Haley wrote:
> On 3/12/20 9:30 AM, Liu, Xin wrote:
>> I expect to have a huge change, but it’s a one-time thing.
> No, please do not do this.
>
> It well mess up the diffs, and it will make auto-merging fail. It will
> add considerable costs to the updates project for every backport. It
> is in every way a bad idea.
>
Such a full-scale formatting change will also affect "hg annotate" (and 
the future GIT equivalent). E.g.,

http://hg.openjdk.java.net/jdk/jdk/annotate/f2a8072492df/src/hotspot/share/memory/universe.cpp

That's very valuable in tracking down why each line of source is written 
the way it is. Without this, it makes bug analysis more difficult.

Thanks
- Ioi