[llvm-bugs] [Bug 42643] New: OpenMP target regions cause CUBLAS_STATUS_INTERNAL_ERROR in libcublas

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=42643

            Bug ID: 42643
           Summary: OpenMP target regions cause
                    CUBLAS_STATUS_INTERNAL_ERROR in libcublas
           Product: OpenMP
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Clang Compiler Support
          Assignee: unassignedclangbugs at nondot.org
          Reporter: csdaley at lbl.gov
                CC: llvm-bugs at lists.llvm.org

Created attachment 22253
  --> https://bugs.llvm.org/attachment.cgi?id=22253&action=edit
Source files and build scripts to reproduce the error

Hello all,

We are trying to use libcublas and OpenMP target offloading in a small
mini-app. When we compile with Clang compiler we find that our second call to
cublasDgemm returns CUBLAS_STATUS_INTERNAL_ERROR - see the top of run-clang.sh
and run-clang.out. We print "** cublasDgemm status-2: 14" when there is
CUBLAS_STATUS_INTERNAL_ERROR return value. The numerical results in this small
mini-app are OK, but eventually cause problems in our full application.

The following alternate compilers work:
* The current IBM XL compiler on OLCF Summit supercomputer - see run-xl.sh and
run-xl.out.
* The PGI compiler, where we replace the OpenMP target offload calls with
OpenACC.

The following 2 versions work with Clang compiler.
* Replace OpenMP target offload code with CUDA code - see
CUBLAS_testcase_cuda.cu. This is the second experiment that is run in
run-clang.sh.
* Replace cublasDgemm calls in libcublas with cblas_dgemm calls in MKL

This indicates that the error is a result of mixing both OpenMP target offload
and libcublas with the Clang compiler. We are using LLVM/Clang from June 06,
but have also reproduced using a version of LLVM/Clang from Feb 20. Our
mini-app is quite complicated, however, it is the simplest mini-app we could
create which still caused CUBLAS_STATUS_INTERNAL_ERROR return value. Please see
run-clang.sh and CUBLAS_testcase.c.

Thanks,
Chris and Fazlay

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