cannot compile graal with gcc 6.1 on 64bit linux and jdk 8u92

[Tortonesi Mauro]

2016-05-30 21:15 GMT+02:00 Doug Simon <doug.simon at oracle.com>:
> Hi Mauro,
>
> As previously mentioned[1], C++11 is not (yet) supported by HotSpot.
>
> The good news is that we’re very close to having prebuilt, JVMCI enabled JDK8 binaries ready. There are remaining steps in terms of finding the appropriate location for hosting the binaries but I expect that to be resolved soon. By mid-June, I expect the binaries will be available.
>
> -Doug
>
> [1] http://mail.openjdk.java.net/pipermail/graal-dev/2016-May/004359.html

Dear Doug,

thank you very much for your kind reply. There must have been a
misunderstanding here, so please let me clarify.

First of all, let me state what is my objective here: I would like to
build Graal on top of JDK 8 (version 72) on my 64-bit Arch Linux
system. (Ultimately, I am interested in finding out if JRuby+Truffle
can bring any significant speedup to my JRuby-based scientific
projects: https://github.com/mtortonesi/symian and
https://github.com/mtortonesi/sisfc.)

>From what I understand, the problem I am having is caused by the fact
that the compiler on my system is GCC version 6.1. In fact, while GCC
adopted the C++98 standard as default until version 6.0 (included):

https://gcc.gnu.org/projects/cxx-status.html#cxx98

it switched to the C++14 standard as default from version 6.1:

https://gcc.gnu.org/projects/cxx-status.html#cxx14

I had well understood from your previous e-mail (and my previous
compilation attempts) that Graal won't compile using C++11. However, I
gave it another try because of:

1) Chris Seaton's implicit invitation not to give up on a Twitter conversation:

https://twitter.com/ChrisGSeaton/status/736544090456723456

2) the assumption that instructing mx to use GCC in C++98 mode was not
going to be so difficult (and the hope that some of Graal's developers
were already using GCC version 6.1 in their day-to-day work);

3) the fact that finding out how to compile Graal with GCC 6.1 would
have also been valuable to other users, thus making it an issue
deserving further investigation.

Elaborating on the second point, I assumed it was possible to compile
Graal with GCC 6.1 by simply using a command like:

CXXFLAGS="-std=c++98" mx --vm server build

However, when I grepped the mx sources for either "CFLAGS", "CC", or
similar words I couldn't find anything. So I am guessing that mx does
not allow to easily specify compilation parameters like make (and most
of the other building tools that I know of) do.

Before giving up on any further compilation attempt and waiting for
JVMCI enabled JDK8 binaries, could I please ask you if there is an
easy way to instruct mx to use the "-std=c++98" flag when calling GCC?

Thank you very much again.


Ciao,
Mauro

-- 
Mauro Tortonesi, Ph.D.

Assistant Professor
Distributed Systems Research Group
Engineering Department
University of Ferrara