RFR(S): 8159056: [aix] Compressed class space not allocated in lower regions

[Lindenmaier, Goetz]

HI David, 

thanks for looking at this!

> I will sponsor this but need an Aarch64 reviewer to confirm  the
> behaviour there is unchanged. If 4G is the first value that should
> succeed I'm not sure what the impact of trying and failing at 1G, 2G and
> 3G are.
I think I don't really understand.  It should only try at 1-3G on aix if 
requested_addr is that small.  On aarch, it is aligned to 4G at the 
start of the loop. 
Do you think there are implications with the OS? Or with the loop
for shared spaces below?

I fixed the other issues:
http://cr.openjdk.java.net/~goetz/wr16/8159056-aix_CCSTest/webrev.02/

Best regards,
  Goetz.


> 
> More below.
> 
> On 9/06/2016 12:21 AM, Lindenmaier, Goetz wrote:
> > Hi,
> >
> > On AIX, test CompressedClassPointers.java fails. This is because
> allocate_metaspace_compressed_klass_ptrs()
> > tries only a single fixed address, which fails on aix.  This change uses the
> loop
> > implemented for aarch to search for a possible location.
> > The change does not affect any other platform. I had to edit the aarch
> code, but
> > it's supposed to behave as before.
> >
> > Please review this change. I please need a sponsor.
> > http://cr.openjdk.java.net/~goetz/wr16/8159056-aix_CCSTest/webrev.01/
> 
> 2958     // the base, 4G alignemnt is helpful, too.
> 
> Typo: alignment
> 
> 2959     size_t incrememnt = AARCH64_ONLY(4*)G;
> 
> Typos: increment
> 
> 2963       if (a == (char *)(32*G)) { incrememnt = 4*G; } // Go faster
> from here on. Zero-based is no more possible.
> 
> Please split into multiple lines. "no more possible" is not correct
> grammar in this context suggest "no longer possible".
> 
> Thanks,
> David
> 
> > Best regards,
> >   Goetz.
> >