Re: URGENT RFR: 8041141: JDK9 emb build failure on PPC platform
- Original Message - Hi Andrew, On 12/06/2014 3:03 AM, Andrew Hughes wrote: - Original Message - http://cr.openjdk.java.net/~dholmes/8041141/webrev/ The recent changes to convert warnings to errors didn't account for some type-punning warnings in our Embedded PPC build due to the use of strict-aliasing. Really we shouldn't be using strict-aliasing so this change (which for some reason is in the open flags.m4 file) brings ppc in-line with all other platforms and sets -fno-strict-aliasing I will be pushing this to jdk9/dev as we need this fixed immediately. Thanks, David Hi David, I just stumbled across this when trying to work out why we are seeing aliasing warnings in the demo code only on PPC builds. They get flagged by our build process. This exclusion of fno-strict-aliasing on PPC seems to date back to 7027910 in OpenJDK 7, where we are seeing the warnings, and there seems to be no explanation as to why it was added in either the code or reviews. It was copied from our internal build instructions. The new build unfortunately required it to be exposed in flags.m4. Ah, ok. Given -fno-strict-aliasing is now being used on all architectures in 9, do you think it's ok to do the same in 7? I could also turn it off on the individual files, but this would duplicate the flag on other architectures and we may then get more PPC-only warnings in future. I think it should be fine in principle. I'm not sure what the actual change in 7 would be. Just this: http://icedtea.classpath.org/hg/release/icedtea7-forest-2.5/jdk/rev/925c4ace5635 I'll look at getting the change backported to 7 8 then. David - Thanks, -- Andrew :) Free Java Software Engineer Red Hat, Inc. (http://www.redhat.com) PGP Key: 248BDC07 (https://keys.indymedia.org/) Fingerprint = EC5A 1F5E C0AD 1D15 8F1F 8F91 3B96 A578 248B DC07
Re: URGENT RFR: 8041141: JDK9 emb build failure on PPC platform
On Thu, Jun 12, 2014 at 3:53 PM, Andrew Haley a...@redhat.com wrote:
Hi,
On 06/11/2014 06:03 PM, Andrew Hughes wrote:
I just stumbled across this when trying to work out why we are seeing
aliasing
warnings in the demo code only on PPC builds. They get flagged by our build
process.
This exclusion of fno-strict-aliasing on PPC seems to date back to 7027910
in OpenJDK
7, where we are seeing the warnings, and there seems to be no explanation as
to why
it was added in either the code or reviews.
Given -fno-strict-aliasing is now being used on all architectures in 9, do
you think
it's ok to do the same in 7? I could also turn it off on the individual
files, but
this would duplicate the flag on other architectures and we may then get
more PPC-only
warnings in future.
Never mind the warnings, -fno-strict-aliasing is essential for correctness.
I agree that we should set this just to be on the safe side.
Notice that for the HotSpot build this is set unconditionally for all
GCC platfoms in make/{bsd,linux,solaris}/makefiles/gcc.make from jdk 7
through 9.
There's also a bug in GCC 4.4.1 which incorrectly prints this waring
even in cases where it shouldn't (see Bug 41874 - Incorrect
dereferencing type-punned pointer will break strict-aliasing rules
warning, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41874)
I just realized that we did all our internal OpenJDK 8/9 Linux/PPC64
builds with --with-extra-cflags=-Wno-strict-aliasing because of that
bug. So I'd appreciate if you'd downport your fix to 7 and 8.
Notice that for OpenJDK 7 this issue only affects 32-bit builds,
because it checks for ($(ARCH),ppc) and ARCH is 'ppc' for 32-bit
builds and ppc64 for 64-bit builds. In 8 this affects both, 32- and
64-bit ppc because it checks for $OPENJDK_TARGET_CPU_ARCH which is
'ppc' for both, the 32- and the 64-bit variant.
Thank you and best regards,
Volker
Andrew.
Re: URGENT RFR: 8041141: JDK9 emb build failure on PPC platform
Hi, On 06/11/2014 06:03 PM, Andrew Hughes wrote: I just stumbled across this when trying to work out why we are seeing aliasing warnings in the demo code only on PPC builds. They get flagged by our build process. This exclusion of fno-strict-aliasing on PPC seems to date back to 7027910 in OpenJDK 7, where we are seeing the warnings, and there seems to be no explanation as to why it was added in either the code or reviews. Given -fno-strict-aliasing is now being used on all architectures in 9, do you think it's ok to do the same in 7? I could also turn it off on the individual files, but this would duplicate the flag on other architectures and we may then get more PPC-only warnings in future. Never mind the warnings, -fno-strict-aliasing is essential for correctness. Andrew.
Re: URGENT RFR: 8041141: JDK9 emb build failure on PPC platform
- Original Message - http://cr.openjdk.java.net/~dholmes/8041141/webrev/ The recent changes to convert warnings to errors didn't account for some type-punning warnings in our Embedded PPC build due to the use of strict-aliasing. Really we shouldn't be using strict-aliasing so this change (which for some reason is in the open flags.m4 file) brings ppc in-line with all other platforms and sets -fno-strict-aliasing I will be pushing this to jdk9/dev as we need this fixed immediately. Thanks, David Hi David, I just stumbled across this when trying to work out why we are seeing aliasing warnings in the demo code only on PPC builds. They get flagged by our build process. This exclusion of fno-strict-aliasing on PPC seems to date back to 7027910 in OpenJDK 7, where we are seeing the warnings, and there seems to be no explanation as to why it was added in either the code or reviews. Given -fno-strict-aliasing is now being used on all architectures in 9, do you think it's ok to do the same in 7? I could also turn it off on the individual files, but this would duplicate the flag on other architectures and we may then get more PPC-only warnings in future. Thanks, -- Andrew :) Free Java Software Engineer Red Hat, Inc. (http://www.redhat.com) PGP Key: 248BDC07 (https://keys.indymedia.org/) Fingerprint = EC5A 1F5E C0AD 1D15 8F1F 8F91 3B96 A578 248B DC07
Re: URGENT RFR: 8041141: JDK9 emb build failure on PPC platform
Hi Andrew, On 12/06/2014 3:03 AM, Andrew Hughes wrote: - Original Message - http://cr.openjdk.java.net/~dholmes/8041141/webrev/ The recent changes to convert warnings to errors didn't account for some type-punning warnings in our Embedded PPC build due to the use of strict-aliasing. Really we shouldn't be using strict-aliasing so this change (which for some reason is in the open flags.m4 file) brings ppc in-line with all other platforms and sets -fno-strict-aliasing I will be pushing this to jdk9/dev as we need this fixed immediately. Thanks, David Hi David, I just stumbled across this when trying to work out why we are seeing aliasing warnings in the demo code only on PPC builds. They get flagged by our build process. This exclusion of fno-strict-aliasing on PPC seems to date back to 7027910 in OpenJDK 7, where we are seeing the warnings, and there seems to be no explanation as to why it was added in either the code or reviews. It was copied from our internal build instructions. The new build unfortunately required it to be exposed in flags.m4. Given -fno-strict-aliasing is now being used on all architectures in 9, do you think it's ok to do the same in 7? I could also turn it off on the individual files, but this would duplicate the flag on other architectures and we may then get more PPC-only warnings in future. I think it should be fine in principle. I'm not sure what the actual change in 7 would be. David - Thanks,
URGENT RFR: 8041141: JDK9 emb build failure on PPC platform
http://cr.openjdk.java.net/~dholmes/8041141/webrev/ The recent changes to convert warnings to errors didn't account for some type-punning warnings in our Embedded PPC build due to the use of strict-aliasing. Really we shouldn't be using strict-aliasing so this change (which for some reason is in the open flags.m4 file) brings ppc in-line with all other platforms and sets -fno-strict-aliasing I will be pushing this to jdk9/dev as we need this fixed immediately. Thanks, David
Re: URGENT RFR: 8041141: JDK9 emb build failure on PPC platform
Hi David: http://cr.openjdk.java.net/~dholmes/8041141/webrev/ The recent changes to convert warnings to errors didn't account for some type-punning warnings in our Embedded PPC build due to the use of strict-aliasing. Really we shouldn't be using strict-aliasing so this change (which for some reason is in the open flags.m4 file) brings ppc in-line with all other platforms and sets -fno-strict-aliasing I will be pushing this to jdk9/dev as we need this fixed immediately. Looks good to me. Tim
Re: URGENT RFR: 8041141: JDK9 emb build failure on PPC platform
Thanks Tim! Changes pushed. David On 22/04/2014 9:57 AM, Tim Bell wrote: Hi David: http://cr.openjdk.java.net/~dholmes/8041141/webrev/ The recent changes to convert warnings to errors didn't account for some type-punning warnings in our Embedded PPC build due to the use of strict-aliasing. Really we shouldn't be using strict-aliasing so this change (which for some reason is in the open flags.m4 file) brings ppc in-line with all other platforms and sets -fno-strict-aliasing I will be pushing this to jdk9/dev as we need this fixed immediately. Looks good to me. Tim
