[Bug target/104714] [nvptx] Means to specify any sm_xx

2022-03-29 Thread vries at gcc dot gnu.org via Gcc-bugs 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104714

Tom de Vries  changed:

   What|Removed |Added

   Target Milestone|--- |12.0
 Resolution|--- |FIXED
 Status|UNCONFIRMED |RESOLVED

--- Comment #3 from Tom de Vries  ---
Added march-map.

[Bug target/104714] [nvptx] Means to specify any sm_xx

2022-03-29 Thread cvs-commit at gcc dot gnu.org via Gcc-bugs 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104714

--- Comment #2 from CVS Commits  ---
The master branch has been updated by Tom de Vries :

https://gcc.gnu.org/g:de0ef04419e90eacf0d1ddb265552a1b08c18d4b

commit r12-7891-gde0ef04419e90eacf0d1ddb265552a1b08c18d4b
Author: Tom de Vries 
Date:   Tue Mar 29 10:32:13 2022 +0200

[nvptx] Add march-map

Say we have an sm_50 board, and we want to run a benchmark using the
highest
possible march setting.

Currently there's march=sm_30, march=sm_35, march=sm_53, but no
march=sm_50.

So, we'd need to pick march=sm_35.

Likewise, for a test script that handles multiple boards, we'd need a
mapping
from native board sm_xx to march, which might have to be updated with newer
gcc releases.

Add an option march-map, such that we can just specify march-map=sm_50, and
let the compiler map this to the appropriate march.

The option is implemented as a list of aliases, such that we have a
somewhat
lengthy (17 lines in total):
...
$ gcc --help=target
  ...
  -march-map=sm_30Same as -misa=sm_30.
  -march-map=sm_32Same as -misa=sm_30.
  ...
  -march-map=sm_87Same as -misa=sm_80.
  -march-map=sm_90Same as -misa=sm_80.
...

This implementation was chosen in the hope that it'll be easier if
we end up with some misa multilib.

It would be nice to have the mapping list generated from an updated
nvptx-sm.def, but for now it's spelled out in nvptx.opt.

Tested on nvptx.

gcc/ChangeLog:

2022-03-29  Tom de Vries  

PR target/104714
* config/nvptx/nvptx.opt (march-map=*): Add aliases.

gcc/testsuite/ChangeLog:

2022-03-29  Tom de Vries  

PR target/104714
* gcc.target/nvptx/march-map.c: New test.

[Bug target/104714] [nvptx] Means to specify any sm_xx

2022-02-28 Thread vries at gcc dot gnu.org via Gcc-bugs 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104714

--- Comment #1 from Tom de Vries  ---
(In reply to Tom de Vries from comment #0)

> [ FWIW, it would be great if we could simply specify -march=native, and have
> gcc query the nvidia driver to see what board there is using
> cuDeviceGetAttribute and CU_DEVICE_ATTRIBUTE_COMPUTE_CAPABILITY_MAJOR and
> CU_DEVICE_ATTRIBUTE_COMPUTE_CAPABILITY_MINOR.  And possibly handle the
> situation of multiple boards by using the minimum.  But, much more involved
> to realize. ]

Though, it might be better to handle this externally, so have a tool:
...
$ cat test.c
#include 
#include 

int compute_capability_major;
int compute_capability_minor;

int
main (void)
{
  cuInit(0);

  int num_devices;
  cuDeviceGetCount (_devices);

  for (int i = 0; i < num_devices; ++i)
{
  CUdevice device;
  cuDeviceGet (, i);

  cuDeviceGetAttribute (_capability_major,
CU_DEVICE_ATTRIBUTE_COMPUTE_CAPABILITY_MAJOR,
device);

  cuDeviceGetAttribute (_capability_minor,
CU_DEVICE_ATTRIBUTE_COMPUTE_CAPABILITY_MINOR,
device);

  printf ("sm_%d%d\n", compute_capability_major, compute_capability_minor);
}

  return 0;
}
...
that compiles like so:
...
$ gcc test.c -I ~/cuda/11.6.0/include -lcuda -o a.out -g
...
and prints:
...
$ ./a.out 
sm_75
...
and then name the tool nvptx-print-native or some such and use:
...
native=$(nvptx-print-native)
$cc ... -march=$native
...
in scripts.