[oe] [meta-java][PATCH] openjdk-8: make GCC6 happy

[Dan McGregor]

On 11 Jul 2016 11:44 a.m., "Otavio Salvador" <
otavio.salvador at ossystems.com.br> wrote:
>
> On Mon, Jul 11, 2016 at 11:33 AM, Khem Raj <raj.khem at gmail.com> wrote:
> > On Mon, Jul 11, 2016 at 4:29 AM, Patrick Ohly <patrick.ohly at intel.com>
wrote:
> >> Dan McGregor <danismostlikely <at> gmail.com> writes:
> >>> From: Daniel McGregor <daniel.mcgregor <at> vecima.com>
> >>>
> >>> GCC 6 sets the default C++ standard to C++14 and introduces dead store
> >>> elimination by default. OpenJDK 8 is not ready for either of these
> >>> changes, so set the C++ standard back to gnu++98 and disable dead
> >>> store elimination.
> >>>
> >>> Switched to using --with-extra-cflags, cxxflags, and ldflags. The
added
> >>> patch fixes building when using those flags, and are needed to get
> >>> CFLAGS into the JDK build in the native case.
> >>
> >> Has anyone tested this on a host system where gcc is still 4.x, like
4.9.2
> >> on Debian Wheezy?
> >>
> >> I'm finding that -fno-lifetime-dse is also getting passed to the gcc
used
> >> for compiling native binaries (obviously in openjdk-8-native, but also
for
> >> some helper executables in openjdk-8). This then breaks the compilation
> >> because older gcc rejects that flag.
> >>
> >> I've briefly toyed with the patch below which worked for
openjdk-8-native,
> >> but not for openjdk-8. I'm just going to work around it by staying on
gcc
> >> 5.x and clearing these extra flags.
> >>
> >> I'm not familiar enough with the openjdk-8 build process to propose a
better
> >> solution, but perhaps someone else has an idea?
> >>
> >> diff --git a/meta-java/recipes-core/openjdk/openjdk-8-common.inc
> >> b/meta-java/recipes-core/openjdk/openjdk-8-common.inc
> >> index dd3d397..060d828 100644
> >> --- a/meta-java/recipes-core/openjdk/openjdk-8-common.inc
> >> +++ b/meta-java/recipes-core/openjdk/openjdk-8-common.inc
> >> @@ -237,6 +237,25 @@ EXTRA_OECONF_append = "\
> >>          --with-update-version=${OPENJDK_UPDATE_VERSION} \
> >>  "
> >>
> >> -CFLAGS_append = " -fno-lifetime-dse -fno-delete-null-pointer-checks"
> >> -CXXFLAGS_append = " -fno-lifetime-dse -fno-delete-null-pointer-checks"
> >> +# GCC 6 sets the default C++ standard to C++14 and introduces dead
store
> >> +# elimination by default. OpenJDK 8 is not ready for either of these
> >> +# changes.
> >> +FLAGS_GCC6 = "-fno-lifetime-dse -fno-delete-null-pointer-checks"
> >> +
> >> +# All supported cross compilers support the compiler flags that were
> >> +# added to make compilation with gcc6 work. But the host compiler for
> >> +# native compilation is a different story: it may be too old (for
example,
> >> +# gcc 4.9.2 on Debian Wheezy). In that case we need to check what the
> >> +# version is and unset the flags when gcc is not yet GCC 6.
> >> +python () {
> >> +    if d.getVar('PN', True).endswith('-native'):
> >> +        import re, subprocess
> >> +        version = subprocess.check_output(d.expand('${CC}
> >> --version').split()).decode('utf-8')
> >> +        m = re.search(r'^gcc.* (\d+)(\.\d+)*$', version, re.MULTILINE)
> >> +        if m and int(m.group(1)) < 6:
> >> +            d.setVar('FLAGS_GCC6', '')
> >> +}
> >> +
> >> +CFLAGS_append = " ${FLAGS_GCC6}"
> >> +CXXFLAGS_append = " ${FLAGS_GCC6}"
> >>  CXX_append = " -std=gnu++98"
> >
> > I can see this needed in several other cases too. May be this should be
made
> > a common utility
>
> I agree but this can be done after we fix meta-java case, so we can
> avoid a bottleneck here.

Yup. I did know about this. I'm glad somebody found a solution.

>
> --
> Otavio Salvador                             O.S. Systems
> http://www.ossystems.com.br        http://code.ossystems.com.br
> Mobile: +55 (53) 9981-7854            Mobile: +1 (347) 903-9750
> --
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