Re: [PATCH,nvptx] Truncate config/nvptx/oacc-parallel.c

[Jakub Jelinek <jakub@redhat.com>]

On Wed, Aug 01, 2018 at 01:33:09PM +0200, Tom de Vries wrote:
> On 07/31/2018 05:55 PM, Cesar Philippidis wrote:
> > Way back in the GCC 5 days when support for OpenACC was in its infancy,
> > we used to rely on having various GOACC_ thread functions in the runtime
> > to implement the execution model, or there lack of (that version of GCC
> > only supported vector level parallelism). However, beginning with GCC 6,
> > those external functions were replaced with internal functions that get
> > expanded by the nvptx BE directly.
> > 
> > This patch removes those stale libgomp functions from the nvptx libgomp
> > target. Is this OK for trunk, or does libgomp still need to maintain
> > backwards compatibility with GCC 5?
> > 
> > This patch has been bootstrapped and regtested for x86_64 with nvptx
> > offloading.
> 
> AFAIU, if you use a GCC 5 nvptx offloading compiler that generates calls
> to these GOACC_ thread functions, you're also expected to use the GCC 5
> nvptx libgomp.a containing these functions, so I don't see any backwards
> compatibility issues here.
> 
> OK for me.
> 
> Jakub, do you have an opinion here?

The ABI compatibility is mainly for libgomp.so which hasn't (ever) bumped
the soname and I don't plan to do that any time soon, but even for the
offloaded libgomp.a I guess one might compile with GCC 5 and link with GCC
9 and expect things not to fail miserably.  This is a *.a library, can't you
e.g. move those functions to a separate *.c file so that they aren't linked
in unless GCC 5 is really used?

	Jakub