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

[Otavio Salvador]

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.

-- 
Otavio Salvador                             O.S. Systems
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