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

[Itaru Kitayama via Openmp-dev]

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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