On Wed, 12 Nov 2014 11:06:26 +0100 Jakub Jelinek <ja...@redhat.com> wrote:
> On Tue, Nov 11, 2014 at 01:53:23PM +0000, Julian Brown wrote: > > A few OpenMP tests fail with the new host_nonshm plugin (with > > failures of the form "libgomp: Trying to update > > [0x605820..0x605824) object that is not mapped"), probably because > > of middle-end bugs. I haven't investigated those in detail. > > Depends how exactly your host_nonshm plugin works. A few tests in the > testsuite use #pragma omp declare target variables, so if host_nonshm > plugin is something like I had on the gomp-4_0-branch initially as > hackish device 257, where code is run on the host, and map directives > simply malloc/free host memory and memcpy stuff around, then without > extra work the #pragma omp declare target variables indeed can't work. > You'd either need to support a strange partially shared memory model, > where #pragma omp declare target variables would be shared (you'd > still need to populate the mapping data structures with those vars > and identity map them), or not so conforming model where you'd map > them on entering the target regions if they aren't mapped yet (the > thing is that then if the variables are changed on the host in > between the start of the program and the target region, you'd use the > changed values instead the values they were originally assigned), or > map them in some constructor (but, how would you know if a > host_nonshm plugin is going to be used in the future). Thanks for the review! I'll work on addressing your comments. Your characterization of the host_nonshm plugin sounds accurate, but OOI, what does the Intel MIC plugin do differently that means it is not subject to the same problem with target variables? > One can always use the intelmicemul plugin to test nonshared-memory > stuff without any HW (provided the host is x86_64/i686), so do we > really need host_nonshm plugin? It might still be useful for testing (non-shm) OpenACC without hardware, I guess (or for pedagogical purposes) -- perhaps we could remove the TARGET_CAP_OPENMP_400 flag, if that's not expected to work. Julian
