Hi Tom!

Ping.


Grüße
 Thomas


On 2022-08-06T21:20:38+0200, I wrote:
> Hi Tom!
>
> Ping.
>
>
> Grüße
>  Thomas
>
>
> On 2022-07-27T17:48:58+0200, I wrote:
>> Hi Tom!
>>
>> Ping.
>>
>>
>> Grüße
>>  Thomas
>>
>>
>> On 2022-07-20T14:46:03+0200, I wrote:
>>> Hi Tom!
>>>
>>> Ping.
>>>
>>>
>>> Grüße
>>>  Thomas
>>>
>>>
>>> On 2022-07-13T10:42:44+0200, I wrote:
>>>> Hi Tom!
>>>>
>>>> Ping.
>>>>
>>>>
>>>> Grüße
>>>>  Thomas
>>>>
>>>>
>>>> On 2022-07-05T16:59:23+0200, I wrote:
>>>>> Hi Tom!
>>>>>
>>>>> Ping.
>>>>>
>>>>>
>>>>> Grüße
>>>>>  Thomas
>>>>>
>>>>>
>>>>> On 2022-06-15T23:18:10+0200, I wrote:
>>>>>> Hi Tom!
>>>>>>
>>>>>> On 2022-05-13T16:20:14+0200, I wrote:
>>>>>>> On 2022-02-04T13:09:29+0100, Tom de Vries via Gcc <gcc@gcc.gnu.org> wrote:
>>>>>>>> On 2/4/22 08:21, Thomas Schwinge wrote:
>>>>>>>>> On 2022-02-03T13:35:55+0000, "vries at gcc dot gnu.org via Gcc-bugs" <gcc-bugs@gcc.gnu.org> wrote:
>>>>>>>>>> I've tested this using (recommended) driver 470.94 on boards:
>>>>>>>
>>>>>>>>>> while iterating over dimensions { -mptx=3.1 , -mptx=6.3 } x { GOMP_NVPTX_JIT=-O0, <default> }.
>>>>>>>>>
>>>>>>>>> Do you use separate (nvptx-none offload target only?) builds for
>>>>>>>>> different '-mptx' variants (likewise: '-misa'), or have you hacked up the
>>>>>>>>> multilib configuration?
>>>>>>>>
>>>>>>>> Neither, I'm using --target_board=unix/foffload= for that.
>>>>>>>
>>>>>>> ACK, I see.  So these flags then only affect GCC/nvptx code generation
>>>>>>> for the actual user code (here: GCC libgomp test cases), but for the
>>>>>>> GCC/nvptx target libraries (such as: libc, libm, libgfortran, libgomp --
>>>>>>> the latter especially relevant for OpenMP), it uses PTX code from one of
>>>>>>> the two "pre-compiled" GCC/nvptx multilibs: default or '-mptx=3.1'.
>>>>>>>
>>>>>>> Meaning, one can't just use such a flag for "completely building code"
>>>>>>> for a specific configuration.  Random example,
>>>>>>> '-foffload-options=nvptx-none=-march=sm_75': as GCC/nvptx target
>>>>>>> libraries aren't being built for '-march=sm_75' multilib,
>>>>>>> '-foffload-options=nvptx-none=-march=sm_75' uses the default multilib,
>>>>>>> which isn't '-march=sm_75'.
>>>>>>>
>>>>>>>
>>>>>>>>   ('gcc/config/nvptx/t-nvptx:MULTILIB_OPTIONS'
>>>>>>>>> etc., I suppose?)  Should we add a few representative configurations to
>>>>>>>>> be built by default?  And/or, should we have a way to 'configure' per
>>>>>>>>> user needs (I suppose: '--with-multilib-list=[...]', as supported for a
>>>>>>>>> few other targets?)?  (I see there's also a new
>>>>>>>>> '--with-multilib-generator=[...]', haven't looked in detail.)  No matter
>>>>>>>>> which way: again, combinatorial explosion is a problem, of course...
>>>>>>>>
>>>>>>>> As far as I know, the gcc build doesn't finish when switching default to
>>>>>>>> higher than sm_35, so there's little point to go to a multilib setup at
>>>>>>>> this point.  But once we fix that, we could reconsider, otherwise,
>>>>>>>> things are likely to regress again.
>>>>>>>
>>>>>>> As far as I remember, several issues have been fixed.  Still waiting for
>>>>>>> Roger's "middle-end: Support ABIs that pass FP values as wider integers"
>>>>>>> or something similar, but that PR104489 issue is being worked around by
>>>>>>> "Limit HFmode support to mexperimental", if I got that right.
>>>>>>>
>>>>>>> Now I'm not suggesting we should now enable all or any random GCC/nvptx
>>>>>>> multilibs, to get all these variants of GCC/nvptx target libraries built;
>>>>>>> especially also given that GCC/nvptx code generation currently doesn't
>>>>>>> make too much use of the new capabilities.
>>>>>>>
>>>>>>> However, we do have a specific request that a customer would like to be
>>>>>>> able to change at GCC 'configure' time the GCC/nvptx default multilib
>>>>>>> (including that being used for building corresponding GCC/nvptx target
>>>>>>> libraries).
>>>>>>>
>>>>>>> Per 'gcc/doc/install.texi', I do see that some GCC targets allow for
>>>>>>> GCC 'configure'-time '--with-multilib-list=[...]', or
>>>>>>> '--with-multilib-generator=[...]', and I suppose we could be doing
>>>>>>> something similar?  But before starting implementing, I'd like your
>>>>>>> input, as you'll be the one to approve in the end.  And/or, maybe you've
>>>>>>> already made up your own ideas about that?
>>>>>>
>>>>>> So, instead of "random GCC/nvptx multilib configuration" (last
>>>>>> paragraph), I've come up with a way to implement our customer's request
>>>>>> (second last paragraph): 'configure' GCC/nvptx '--with-arch=sm_70'.
>>>>>>
>>>>>> I think I've implemented this in a way so that "random GCC/nvptx multilib
>>>>>> configuration" may eventually be implemented on top of that.  For easy
>>>>>> review/testing I've split my changes into three commits, see attached
>>>>>> "nvptx: Make default '-misa=sm_30' explicit",
>>>>>> "nvptx: Introduce dummy multilib option for default '-misa=sm_30'",
>>>>>> "nvptx: Allow '--with-arch' to override the default '-misa'".
>>>>>>
>>>>>> To the best of my knowledge, the first two patches do not change any
>>>>>> user-visible behavior (I generally 'diff'ed target libraries, and
>>>>>> compared a good number of 'gcc -print-multi-directory [flags]'), and
>>>>>> likewise with the third patch, given implicit (default) or explicit
>>>>>> '--with-arch=sm_30', and that with '--with-arch=sm_70', for example, the
>>>>>> '-misa=sm_70' multilib variants are used for implicit (default) or
>>>>>> explicit '-misa=sm_70' or higher, and the '-misa=sm_30' multilib variants
>>>>>> are used for explicit lower '-misa'.
>>>>>>
>>>>>> What do you think, OK to push to master branch?
>>>>>>
>>>>>>
>>>>>> Grüße
>>>>>>  Thomas


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