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

[Erik Joelsson]

Looks good.

/Erik


On 2016-12-20 09:30, Thomas Stüfe wrote:
> Hi guys,
>
> updated webrev: 
> http://cr.openjdk.java.net/~stuefe/webrevs/8171408-aix-TOC-overflow-when-linking-the-gtest-libjvm/webrev.01/webrev/ 
> <http://cr.openjdk.java.net/%7Estuefe/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 
> <mailto:thomas.stuefe at gmail.com>> wrote:
>
>     Hi Erik,
>
>     On Tue, Dec 20, 2016 at 9:17 AM, Erik Joelsson
>     <erik.joelsson at oracle.com <mailto: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
>             <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/
>             <http://cr.openjdk.java.net/%7Estuefe/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
>
>
>
>