[RFC] Offloading and automatic linking of libraries

[Joseph Myers]

On Thu, 24 Sep 2020, Tobias Burnus wrote:

> Hi all,
> 
> we got the user comment that it is far from obvious to
> use  -foffload=-latomic if the following error shows up:
> 
> unresolved symbol __atomic_compare_exchange_16
> collect2: error: ld returned 1 exit status
> mkoffload: fatal error: ..../powerpc64le-none-linux-gnu-accel-nvptx-none-gcc
> returned 1 exit status
> 
> In principle, the same issue pops up with -lm and -lgfortran,
> which on the host are automatically linked for g++ (-lm) and
> for gfortran (both) but not gcc.

As discussed in bug 81358, I think --as-needed -latomic --no-as-needed 
should be used by the driver by default (when the compiler is configured 
with libatomic supported).  The same ought to apply for the offloading 
libatomic as well: it should be linked in automatically when needed.

-- 
Joseph S. Myers
joseph@codesourcery.com