[all-commits] [llvm/llvm-project] 72552f: [OpenMP][SystemZ] Compile __kmpc_omp_task_begin_if...

[Ilya Leoshkevich via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 72552fc5cbc0cf2f44508948a075d14f0d5aa2b3
      https://github.com/llvm/llvm-project/commit/72552fc5cbc0cf2f44508948a075d14f0d5aa2b3
  Author: Ilya Leoshkevich <iii at linux.ibm.com>
  Date:   2023-11-09 (Thu, 09 Nov 2023)

  Changed paths:
    M openmp/runtime/src/kmp_tasking.cpp

  Log Message:
  -----------
  [OpenMP][SystemZ] Compile __kmpc_omp_task_begin_if0() with backchain (#71834)

OpenMP runtime fails to build on SystemZ with clang with the following
error message:

    LLVM ERROR: Unsupported stack frame traversal count

__kmpc_omp_task_begin_if0() uses OMPT_GET_FRAME_ADDRESS(1), which
delegates to __builtin_frame_address(), which in turn works with nonzero
values on SystemZ only if backchain is in use. If backchain is not in
use, the above error is emitted.

Compile __kmpc_omp_task_begin_if0() with backchain. Note that this only
resolves the build error. If at runtime its caller is compiled without
backchain, __builtin_frame_address() will produce an incorrect value,
but will not cause a crash. Since the value is relevant only for OMPT,
this is acceptable.