[all-commits] [llvm/llvm-project] d38788: [Clang][OpenMP] Avoid unnecessary privatization of...

[Shilei Tian via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: d38788b357ad29083eb3b03027db908559aae2a6
      https://github.com/llvm/llvm-project/commit/d38788b357ad29083eb3b03027db908559aae2a6
  Author: Shilei Tian <tianshilei1992 at gmail.com>
  Date:   2020-10-27 (Tue, 27 Oct 2020)

  Changed paths:
    M clang/lib/CodeGen/CGOpenMPRuntime.cpp
    M clang/lib/CodeGen/CGStmtOpenMP.cpp
    M clang/test/OpenMP/target_codegen.cpp
    M clang/test/OpenMP/target_enter_data_depend_codegen.cpp
    M clang/test/OpenMP/target_exit_data_depend_codegen.cpp
    M clang/test/OpenMP/target_parallel_depend_codegen.cpp
    M clang/test/OpenMP/target_parallel_for_codegen.cpp
    M clang/test/OpenMP/target_parallel_for_depend_codegen.cpp
    M clang/test/OpenMP/target_parallel_for_simd_depend_codegen.cpp
    M clang/test/OpenMP/target_simd_depend_codegen.cpp
    M clang/test/OpenMP/target_teams_codegen.cpp
    M clang/test/OpenMP/target_teams_depend_codegen.cpp
    M clang/test/OpenMP/target_teams_distribute_codegen.cpp
    M clang/test/OpenMP/target_teams_distribute_depend_codegen.cpp
    M clang/test/OpenMP/target_teams_distribute_parallel_for_depend_codegen.cpp
    M clang/test/OpenMP/target_teams_distribute_parallel_for_simd_depend_codegen.cpp
    M clang/test/OpenMP/target_teams_distribute_simd_codegen.cpp
    M clang/test/OpenMP/target_teams_distribute_simd_depend_codegen.cpp
    M clang/test/OpenMP/target_update_depend_codegen.cpp

  Log Message:
  -----------
  [Clang][OpenMP] Avoid unnecessary privatization of mapper array when there is no user defined mapper

In current implementation, if it requires an outer task, the mapper array will be privatized no matter whether it has mapper. In fact, when there is no mapper, the mapper array only contains number of nullptr. In the libomptarget, the use of mapper array is `if (mappers_array && mappers_array[i])`, which means we can directly set mapper array to nullptr if there is no mapper. This can avoid unnecessary data copy.

In this patch, the data privatization will not be emitted if the mapper array is nullptr. When it comes to the emit of task body, the nullptr will be used directly.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D90101