[Openmp-dev] Offloading application build with a Trunk Debug Clang is so slow

[Itaru Kitayama via Openmp-dev]

Trunk Clang built with setting both variables to -DCMAKE_BUILD_TYPE=Release
-DLIBOMPTARGET_ENABLE_DEBUG=False
builds my application in a minute or so.

On Thu, Dec 19, 2019 at 8:18 AM Itaru Kitayama <itaru.kitayama at gmail.com>
wrote:

> The CMake was executed as below:
>
> cmake -GNinja -DCMAKE_BUILD_TYPE=Debug -DLIBOMPTARGET_ENABLE_DEBUG=True
> -DCMAKE_INSTALL_PREFIX=$SCRATCH/pcp0151/opt/clang/${today}
> -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++
> -DGCC_INSTALL_PREFIX=/gpfs/software/opt/gcc/7.2.0/
> -DLLVM_ENABLE_PROJECTS="clang;openmp;libcxx;libcxxabi;lld"
> -DCLANG_OPENMP_NVPTX_DEFAULT_ARCH=sm_60
> -DLIBOMPTARGET_NVPTX_COMPUTE_CAPABILITIES=60
> -DLLVM_TARGETS_TO_BUILD="PowerPC;NVPTX"
> $SCRATCH/pcp0151/projects/llvm-project/llvm
>
> On Thu, Dec 19, 2019 at 7:57 AM Itaru Kitayama <itaru.kitayama at gmail.com>
> wrote:
>
>> The Clang at this commit:
>> commit 1c49553c19a7044fbbf4528b732926f19f210e54
>> Author: Bjorn Pettersson <bjorn.a.pettersson at ericsson.com>
>> Date:   Thu Dec 12 20:51:13 2019 +0100
>> [kitayama1 at juron1-adm pcp0151]$ time clang++ -g -fopenmp
>> -fopenmp-targets=nvptx64 mini.cpp
>>
>> real 0m2.344s
>> user 0m2.231s
>> sys 0m0.049s
>> Release Clang 9
>> [[kitayama1 at juron1-adm pcp0151]$ time clang++ -g -fopenmp
>> -fopenmp-targets=nvptx64 mini.cpp
>>
>> real 0m0.693s
>> user 0m0.533s
>> sys 0m0.047s
>>
>> On Thu, Dec 19, 2019 at 5:32 AM Jon Chesterfield <
>> jonathanchesterfield at gmail.com> wrote:
>>
>>> Ah, OK. In that case I still suspect a regression in clang, as opposed
>>> to a change in the library. Does the compile time remain very slow if you
>>> roll deviceRTL back by a few days?
>>>
>>> On Wed, Dec 18, 2019 at 8:30 PM Itaru Kitayama <itaru.kitayama at gmail.com>
>>> wrote:
>>>
>>>> Sorry, of course it should include this #pragma
>>>> omp target parallel for for(;;) {}. My local Debug Clang is updated
>>>> daily, so the tool chain is pretty much up to date.
>>>>
>>>> On Thu, Dec 19, 2019 at 5:24 Jon Chesterfield <
>>>> jonathanchesterfield at gmail.com> wrote:
>>>>
>>>>> On Wed, Dec 18, 2019 at 8:13 PM Itaru Kitayama <
>>>>> itaru.kitayama at gmail.com> wrote:
>>>>>
>>>>>> The app build time increases can be reproduced with a simple int
>>>>>> main() {} code.
>>>>>>
>>>>>
>>>>> I thought the problem was with the compile time of deviceRTL.
>>>>>
>>>>> If you're compiling int main() {}, then there's no openmp involved, so
>>>>> that seems out of scope for this list.
>>>>>
>>>>>
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