RFR(xs): 8171408: [aix] TOC overflow when linking the gtest libjvm.so

[Volker Simonis]

Looks good now!

Thanks,
Volker


On Tue, Dec 20, 2016 at 9:30 AM, Thomas Stüfe <thomas.stuefe at gmail.com> wrote:
> Hi guys,
>
> updated webrev:
> http://cr.openjdk.java.net/~stuefe/webrevs/8171408-aix-TOC-overflow-when-linking-the-gtest-libjvm/webrev.01/webrev/
>
> Only change is that I removed the offending filter-out expression. This
> means that gtest modules are compiled with both -qpic followed by
> -qpic=large, but the latter should take precedence, so it is ok. Also keeps
> the makefile simple.
>
> Kind Regards, Thomas
>
> On Tue, Dec 20, 2016 at 9:21 AM, Thomas Stüfe <thomas.stuefe at gmail.com>
> wrote:
>>
>> Hi Erik,
>>
>> On Tue, Dec 20, 2016 at 9:17 AM, Erik Joelsson <erik.joelsson at oracle.com>
>> wrote:
>>>
>>> Hello,
>>>
>>> I understand why you want to filter out the -qpic flag from the general
>>> JVM_CFLAGS, but that kind of logic is brittle so we try to avoid it unless
>>> absolutely necessary. I prefer to just rely on the tools treating command
>>> line options as the last one takes precedence. I assume the AIX compiler
>>> behaves that way too and that a -qpic=large will override a -qpic earlier on
>>> the command line. We have consciously designed SetupNativeCompilation to add
>>> all the *FLAGS in the order of most specific flags last for this reason.
>>>
>>
>> You are right, and Volker just complained about the same thing :) I'll
>> post an updated ref where I just rely on qpic=large following qpic. I was
>> not happy with that filter-out expression either.
>>
>> ..Thomas
>>
>>>
>>> So, could you try removing the filtering and see if it still works?
>>>
>>> /Erik
>>>
>>>
>>>
>>> On 2016-12-18 13:50, Thomas Stüfe wrote:
>>>>
>>>> Hi all,
>>>>
>>>> please take a look at this small fix. In short, on AIX when linking the
>>>> gtest version of libjvm.so, the TOC overflows.
>>>>
>>>> So the gtest libjvm.so must be linked with -bbigtoc, in contrast to the
>>>> regular libjvm.so, which has no problems and can keep using a small TOC.
>>>>
>>>> Also, I compile all gtest objects with -qpic=large. Note that this only
>>>> affects the gtest objects. The regular objects - which the gtest
>>>> libjvm.so
>>>> shares with the regular libjvm.so - I left at -qpic[=small]. This means
>>>> we
>>>> pay a bit of a performance overhead in the gtest libjvm.so but leave the
>>>> regular libjvm.so at its optimal linker settings.
>>>>
>>>> Issue:
>>>> https://bugs.openjdk.java.net/browse/JDK-8171408
>>>>
>>>> Webrev:
>>>>
>>>> http://cr.openjdk.java.net/~stuefe/webrevs/8171408-aix-TOC-overflow-when-linking-the-gtest-libjvm/webrev.00/
>>>>
>>>> (Hope the webrev link works, the webserver is still down).
>>>>
>>>> Kind Regards, Thomas
>>>
>>>
>>
>