[Openmp-dev] Target architecture does not support unified addressing

[Gheorghe-Teod Bercea via Openmp-dev]

Hi Itaru,

We did not test those features on an sm_60 machine like a Pascal GPU so I 
can't guarantee it will work. I suggest you enable it locally and see how 
it performs.
You only need to make a small change in "void 
CGOpenMPRuntimeNVPTX::checkArchForUnifiedAddressing(const OMPRequiresDecl 
*D)" to allow sm_60 to be accepted as a valid target.

Thanks,

--Doru




From:   Itaru Kitayama via Openmp-dev <openmp-dev at lists.llvm.org>
To:     Alexey Bataev <a.bataev at outlook.com>
Cc:     openmp-dev <openmp-dev at lists.llvm.org>
Date:   11/05/2019 06:04 PM
Subject:        [EXTERNAL] Re: [Openmp-dev] Target architecture does not 
support unified addressing
Sent by:        "Openmp-dev" <openmp-dev-bounces at lists.llvm.org>



Can you say briefly as to why SM60, while it is capable of handing unified 
addresses, is not supported in Clang?

On Wed, Nov 6, 2019 at 7:56 AM Alexey Bataev <a.bataev at outlook.com> wrote:
Yes, it is enforced in clang.

Best regards, 
Alexey Bataev

5 нояб. 2019 г., в 17:38, Itaru Kitayama <itaru.kitayama at gmail.com> 
написал(а):

 
Thank you, Alexey. Now I am seeing: 

$ clang++ -fopenmp -fopenmp-targets=nvptx64 tmp.cpp
tmp.cpp:1:22: error: Target architecture sm_60 does not support unified 
addressing
#pragma omp requires unified_shared_memory
                     ^
1 error generated.

P100 is a SM60 device, but supports unified memory. Is a requirement sm_70 
equals or greater
enforced in Clang? 

On Wed, Nov 6, 2019 at 5:07 AM Alexey Bataev <a.bataev at outlook.com> wrote:
Most probably, you use default architecture, i.e. sm_35. You need to build 
clang with sm_35, sm_70, ... supported archs. Plus, your system must 
support unified memory.
I updated error message in the compiler, now it says what target 
architecture you use .
-------------
Best regards,
Alexey Bataev
05.11.2019 3:01 PM, Itaru Kitayama пишет:
I’ve been building trunk Clang locally targeting the P100 device attached 
to Host. Should I check the tool chain?

On Tue, Nov 5, 2019 at 23:47 Alexey Bataev <a.bataev at outlook.com> wrote:
You're building you code for the architecture that does not support 
unified memory, say sm_35. Unified memory only supported for architectures 
>= sm_70. 
-------------
Best regards,
Alexey Bataev
05.11.2019 3:16 AM, Itaru Kitayama via Openmp-dev пишет:
Hi, 
Using a pragma like below:

$ cat tmp.cpp
#pragma omp requires unified_shared_memory

int main() {
}

produces en error on a POWER8 based system with P100 devices (that support 
unified memory).

$ clang++ -fopenmp -fopenmp-targets=nvptx64 tmp.cpp
tmp.cpp:1:22: error: Target architecture does not support unified 
addressing
#pragma omp requires unified_shared_memory
                     ^
1 error generated.

The Clang is locally and natively built with the appropriate capability, 
so 
what does this mean?


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