[Llvm-bgq-discuss] bgclang r192411-20131010 on vesta/mira (with LTO)

[Hal Finkel]

Hello,

A quick update: the install last night would not handle LTO when linking dynamically. I've fixed this now.

For those maintaining their own installs, an updated bgclang-binutils RPM (and SRPM) are available on the trac page: https://trac.alcf.anl.gov/projects/llvm-bgq

 -Hal

----- Original Message -----
> Hello again,
> 
> I've updated our bgclang install on vesta and mira to
> r192411-20131010.
> 
> The primary motivation behind this release is to let you all play
> with a new feature: link-time optimization (LTO). I consider LTO
> here to be alpha quality, and I already know of at least one bug
> (building HACC with LTO and debugging symbols (-g) will crash the
> link-time optimizer). Nevertheless, the potential performance
> benefit is significant, and so please feel free to try it and
> provide feedback. Here's how:
> 
>  1. Pass the command-line argument -flto to bgclang when both
>  compiling and linking (you'll also want -O2 or -O3).
> 
>  2. If you build using static archives (.a files), you need to
>  construct them using bundled 'ar' utility. bgclang-ar (and
>  equivalently powerpc64-bgq-linux-clang-ar) are provided in the wbin
>  directory for this purpose. If you'd like to view the symbols in
>  these archives, the system 'nm' utility will not help you. Use
>  bgclang-nm (or powerpc64-bgq-linux-clang-nm) from the wbin
>  directory instead.
> 
>     If you fail to use the bundled 'ar' utility, and instead use the
>     system 'ar', when you link you'll likely receive an error
>     message like this:
>       error adding symbols: Archive has no index; run ranlib to add
>       one
> 
> For those maintaining their own installs, RPMs (and SRPMs) are
> available on the trac page:
> https://trac.alcf.anl.gov/projects/llvm-bgq
> 
> Thanks again,
> Hal
> 
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory