RFR(S): 8158260: PPC64: unaligned Unsafe.getInt can lead to the generation of illegal instructions

[Lindenmaier, Goetz]

Hi Volker, 

I've looked at the change, it's fine.  Thanks for fixing this.

Best regards,
  Goetz.

> -----Original Message-----
> From: ppc-aix-port-dev [mailto:ppc-aix-port-dev-
> bounces at openjdk.java.net] On Behalf Of Volker Simonis
> Sent: Dienstag, 14. Juni 2016 20:12
> To: hotspot compiler <hotspot-compiler-dev at openjdk.java.net>; ppc-aix-
> port-dev at openjdk.java.net; aarch64-port-dev at openjdk.java.net
> Cc: Hiroshi H Horii <HORII at jp.ibm.com>; Gustavo Romero
> <gromero at linux.vnet.ibm.com>
> Subject: RFR(S): 8158260: PPC64: unaligned Unsafe.getInt can lead to the
> generation of illegal instructions
> 
> Hi,
> 
> can I please get a review for this small change which fixes a code
> generation problem on ppc64:
> 
> http://cr.openjdk.java.net/~simonis/webrevs/2016/8158260/
> https://bugs.openjdk.java.net/browse/JDK-8158260
> 
> In the case where we access an unaligned address trough Unsafe, we
> could generate an illegal instruction because we didn't correctly
> specify the memory operand of some match rules. The fix is trivial.
> 
> Although this change is ppc64-specific I think I need a sponsor
> because the change contains a new regression test which is supposed to
> run on all platforms.
> 
> On platforms where Unsafe.unalignedAccess() will return false (e.g.
> Solaris/SPARC) this test will return immediately (and I've verified
> that it works).
> 
> I've also added aarch64 to the list of recipients because on aarch64
> Unsafe.unalignedAccess() is apparently supported and it would be nice
> if somebody could check that the new regression test is indeed working
> there.
> 
> @Hiroshi, Gustavo: could you please verify that this change is enough
> to fix the initial problems you've observed when running Cassandra on
> Linux/ppc64? The changes from ppc64.ad should easily apply to the
> 8u-dev repository. Once we've got this into jdk9 I'll trigger a
> downport request to get the fix into jdk8 as well.
> 
> Thank you and best regards,
> Volker