Re: [Patch] offload-defaulted: Config option to silently ignore uninstalled offload compilers

[Matthias Klose <doko@ubuntu.com>]

On 4/27/21 12:22 PM, Tobias Burnus wrote:
> This is based on Jakub's patch* which is used with many distributions – and is has
> to be maintained by all of them; otherwise issues like lp #1878760 might creep in,
> as discussed in #gcc yesterday. - As I am a huge fan of reducing code duplication
> and local patches, I propose to add it to GCC proper behind a configure flag.
> 
> The patch idea is: offloading support is configured for one or multiple offload
> devices
> but compilation silently ignores a target if its offload compiler is not found at
> compile time and also dlopen errors of the associated libgomp plugin is also
> silently ignored such that also the system where the program is run do not show
> a run-time error.
> 
> This makes a lot of sense for distribution compilers – as it permits to configure
> GCC to support offloading to one/multiple offload targets, but the actual
> offload compiler and the run-time support can be put into separate, optional
> packages.
> 
> (When -foffload=$TARGET is specified explicitly, it still gives
> an error if the offload compiler is not installed; this does not not affect the
> libgomp/run-time side.)
> 
> However, for nondistro builds, compilers are usually installed "as is" and not
> split into different packages – thus, compilation or run-time issues should give
> an error.
> 
> Hence, the distro behaviour is only active when configured with
> --enable-offload-defaulted.
> 
> Comments? OK for mainline?

please document that option in gcc/doc/install.texi.

Matthias