Default compute dimensions (runtime)

[Julian Brown]

Hi,

Continuing the thread from here:

https://gcc.gnu.org/ml/gcc-patches/2016-02/msg00198.html

On Wed, 3 Feb 2016 19:52:09 +0300
Alexander Monakov <amonakov@ispras.ru> wrote:

> On Wed, 3 Feb 2016, Nathan Sidwell wrote:
> > You can only override at runtime those dimensions that you said
> > you'd override at runtime when you compiled your program.  
> 
> Ah, I see.  That's not obvious to me, so perhaps added documentation
> can be expanded to explain that?  (I now see that the plugin silently
> drops user-provided dimensions where a value recorded at compile time
> is present; not sure if that'd be worth a runtime diagnostic, could
> be very noisy) 

This version of the patch has slightly-expanded documentation.

> > > I don't see why you say that because cuDeviceGetAttribute provides
> > > CU_DEVICE_ATTRIBUTE_WARP_SIZE,
> > > CU_DEVICE_ATTRIBUTE_MAX_THREADS_PER_BLOCK,
> > > CU_DEVICE_ATTRIBUTE_MAX_GRID_DIM_X (which is not too useful for
> > > this case) and cuFuncGetAttribute that allows to get a
> > > per-function thread limit. There's a patch on gomp-nvptx branch
> > > that adds querying some of those to the plugin.  
> > 
> > thanks.  There doesn't appear to be one for number of physical CTAs
> > though, right?  
> 
> Sorry, I don't understand the question: CTA is a logical entity.  One
> could derive limit of possible concurrent CTAs from number of SMs
> (CU_DEVICE_ATTRIBUTE_MULTIPROCESSOR_COUNT) multiplied by how many
> CTAs fit on one multiprocessor.  The latter figure can be taken as a
> rough worst-case value, or semi-intelligent per-kernel estimate based
> on register limits (there's code on gomp-nvptx branch that does
> this), or one can use the cuOcc* API to ask the driver for a precise
> per-kernel figure.

While the runtime part of the patch already appears to have been
committed as part of the following patch:

https://gcc.gnu.org/ml/gcc-patches/2016-02/msg01589.html

The compile-time part of the patch has not made it upstream yet. Thus,
this rebased and retested patch consists of the parsing changes (for
-fopenacc-dim=X:Y:Z, allowing '-') and warning changes (for strange
partitioning choices), plus associated testsuite adjustments.

Tested with offloading to NVPTX and bootstrapped.

OK for trunk?

Thanks,

Julian

20xx-xx-xx  Nathan Sidwell  <nathan@acm.org>
	    Tom de Vries  <tdevries@suse.de>
	    Thomas Schwinge  <thomas@codesourcery.com>
	    Julian Brown  <julian@codesourcery.com>

	gcc/
	* doc/invoke.texi (fopenacc-dim): Update.
	* omp-offload.c (oacc_parse_default_dims): Update.
	(oacc_validate_dims): Emit warnings about strange partitioning choices.

	gcc/testsuite/
	* c-c++-common/goacc/acc-icf.c: Update.
	* c-c++-common/goacc/parallel-dims-1.c: Likewise.
	* c-c++-common/goacc/parallel-reduction.c: Likewise.
	* c-c++-common/goacc/pr70688.c: Likewise.
	* c-c++-common/goacc/routine-1.c: Likewise.
	* c-c++-common/goacc/uninit-dim-clause.c: Likewise.
	* gfortran.dg/goacc/parallel-tree.f95: Likewise.
	* gfortran.dg/goacc/routine-4.f90: Likewise.
	* gfortran.dg/goacc/routine-level-of-parallelism-1.f90: Likewise.
	* gfortran.dg/goacc/uninit-dim-clause.f95: Likewise.

	libgomp/
	* testsuite/libgomp.oacc-c-c++-common/loop-g-1.c: Add -w.
	* testsuite/libgomp.oacc-c-c++-common/loop-g-2.c: Likewise.
	* testsuite/libgomp.oacc-c-c++-common/loop-red-g-1.c: Likewise.
	* testsuite/libgomp.oacc-c-c++-common/loop-red-w-1.c: Likewise.
	* testsuite/libgomp.oacc-c-c++-common/loop-red-w-2.c: Likewise.
	* testsuite/libgomp.oacc-c-c++-common/loop-warn-1.c: New.
	* testsuite/libgomp.oacc-c-c++-common/firstprivate-1.c: Update.
	* testsuite/libgomp.oacc-c-c++-common/loop-auto-1.c: Likewise.
	* testsuite/libgomp.oacc-c-c++-common/loop-w-1.c: Likewise.
	* testsuite/libgomp.oacc-c-c++-common/mode-transitions.c: Likewise.
	* testsuite/libgomp.oacc-c-c++-common/parallel-dims.c: Likewise.
	* testsuite/libgomp.oacc-c-c++-common/private-variables.c: Likewise.
	* testsuite/libgomp.oacc-c-c++-common/reduction-7.c: Likewise.
	* testsuite/libgomp.oacc-c-c++-common/routine-g-1.c: Likewise.
	* testsuite/libgomp.oacc-c-c++-common/routine-w-1.c: Likewise.
	* testsuite/libgomp.oacc-fortran/par-reduction-2-1.f: Likewise.
	* testsuite/libgomp.oacc-fortran/par-reduction-2-2.f: Likewise.
	* testsuite/libgomp.oacc-fortran/pr84028.f90: Likewise.
	* testsuite/libgomp.oacc-fortran/private-variables.f90: Likewise.
	* testsuite/libgomp.oacc-fortran/routine-7.f90: Likewise.
	* testsuite/libgomp.oacc-c-c++-common/loop-default-compile.c: New.
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