On Wed, Feb 24, 2016 at 17:13:35 +0100, Thomas Schwinge wrote:
> On Tue, 23 Feb 2016 08:37:07 +0100, Tom de Vries <tom_devr...@mentor.com>
> wrote:
> > On 22/02/16 19:07, Ilya Verbin wrote:
> > > 2016-02-22 18:13 GMT+03:00 Thomas Schwinge<tho...@codesourcery.com>:
> > >> >On Sat, 20 Feb 2016 13:54:20 +0300, Ilya Verbin<iver...@gmail.com>
> > >> >wrote:
> > >>> >>On Fri, Feb 19, 2016 at 15:53:08 +0100, Jakub Jelinek wrote:
> > >>>> >> >On Wed, Feb 10, 2016 at 08:19:34PM +0300, Ilya Verbin wrote:
> > >>>>> >> > >This patch adds crtoffload{begin,end}.o to all -fopenmp
> > >>>>> >> > >programs, if they exist.
>
> > >>> >>Thomas, could you please test it using nvptx
> > >> >
> > >> >It mostly;-) works. With nvptx offloading enabled (which you don't
> > >> >have, do you?), I'm seeing one test case regress:
> > >> >
> > >> > [-PASS:-]{+FAIL:+}
> > >> > libgomp.oacc-c/../libgomp.oacc-c-c++-common/parallel-dims-2.c
> > >> > -DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 (test for errors, line
> > >> > 9)
> > >> > [-PASS:-]{+FAIL:+}
> > >> > libgomp.oacc-c/../libgomp.oacc-c-c++-common/parallel-dims-2.c
> > >> > -DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 (test for errors, line
> > >> > 13)
> > >> > PASS:
> > >> > libgomp.oacc-c/../libgomp.oacc-c-c++-common/parallel-dims-2.c
> > >> > -DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 (test for excess errors)
> > >> > [-PASS:-]{+FAIL:+}
> > >> > libgomp.oacc-c/../libgomp.oacc-c-c++-common/parallel-dims-2.c
> > >> > -DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 execution test
> > >> >
> > >> >(Same for C++.) That testcase, just recently added by Tom in r233237
> > >> >"Handle -fdiagnostics-color in lto", specifies 'dg-additional-options
> > >> >"-flto -fno-use-linker-plugin"'. Is that now an unsupported
> > >> >combination/configuration? (I have not yet looked in detail, but it
> > >> >appears as if the offloading compilers are no longer being run for
> > >> >-fno-use-linker-plugin.)
> > > Yes, it's really hard to fix the "lto + non-lto objects" issue for
> > > no-use-linker-plugin LTO path. In this patch lto-plugin prepares a
> > > list of objects files with offloading and passes it to lto-wrapper, so
> > > I believe we should consider offloading without lto-plugin as
> > > unsupported. I'll update wiki when the patch will be committed.
>
> Aha, I see. I guess there's no point in keeping offloading supported for
> the -fno-lto (default) with -fno-use-linker-plugin configuration?
>
> Ilya, then please remove
> libgomp/testsuite/libgomp.oacc-c-c++-common/parallel-dims-2.c as part of
> your patch, unless Tom thinks it should be changed to a -flto test, but
> without -fno-use-linker-plugin?
OK.
> > Shouldn't we error (or at least warn) then if we compile a file
> > containing an offload construct with fopenacc/fopenmp and
> > -fno-use-linker-plugin?
>
> Yes, that makes sense to me, too. (Note that, as I understand it,
> -fno-use-linker-plugin may also be the default for certain GCC
> configurations...) Aside from spec stuff in gcc/gcc.c relating to
> LINK_PLUGIN_SPEC, I see there's some code in
> gcc/gcc.c:driver::maybe_run_linker evaluating the three possible values
> of HAVE_LTO_PLUGIN, but I have not yet thought about how and where to
> conditionalize the diagnostic if attempting to do offloading in an
> unsupported (-fno-use-linker-plugin) configuration.
To print this error someone has to detect that at least one object contains
offload sections, only linker plugin and lto-wrapper can do it. But if linker
plugin is absent, the lto-wrapper have to open all objects, scan for all
sections, etc. Looks like too much overhead for a single diagnostic.
-- Ilya
