[PATCH] D84422: [OpenMP] Fix `present` for exit from `omp target data`

[Joel E. Denny via Phabricator via llvm-commits]

jdenny created this revision.
jdenny added reviewers: grokos, ABataev, jdoerfert.
Herald added subscribers: llvm-commits, openmp-commits, cfe-commits, sstefan1, guansong, yaxunl.
Herald added projects: clang, OpenMP, LLVM.

Without this patch, the following example fails but shouldn't
according to my read of OpenMP TR8:

  #pragma omp target enter data map(alloc:i)
  #pragma omp target data map(present, alloc: i)
  {
    #pragma omp target exit data map(delete:i)
  } // fails presence check here

OpenMP TR8 sec. 2.22.7.1 "map Clause", p. 321, L23-26 states:

> If the map clause appears on a target, target data, target enter
>  data or target exit data construct with a present map-type-modifier
>  then on entry to the region if the corresponding list item does not 
>  appear in the device data environment an error occurs and the 
>  program terminates.

I see no corresponding statement about the exit from a region.  Thus,
the `present` modifier should:

1. Check for presence upon entry into a `target exit data` construct.
2. Should not check for presence upon exit from a `target data` region, as in the above example.

The problem is that Clang calls the same set of
`__tgt_target_data_end_*` functions for these two cases, making them
indistinguishable in the runtime where the presence check is
implemented.  To fix that, this patch changes Clang to generate calls
to a new set of runtime functions, `__tgt_target_exit_data_*`, for the 
case of `target exit data`.

For symmetry, this patch makes a similar change for `target enter
data`, but that change isn't required for the above fix.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D84422

Files:
  clang/lib/CodeGen/CGOpenMPRuntime.cpp
  clang/test/OpenMP/declare_mapper_codegen.cpp
  clang/test/OpenMP/target_enter_data_codegen.cpp
  clang/test/OpenMP/target_enter_data_depend_codegen.cpp
  clang/test/OpenMP/target_exit_data_codegen.cpp
  clang/test/OpenMP/target_exit_data_depend_codegen.cpp
  clang/test/OpenMP/target_map_member_expr_array_section_codegen.cpp
  llvm/include/llvm/Frontend/OpenMP/OMPKinds.def
  openmp/libomptarget/include/omptarget.h
  openmp/libomptarget/src/exports
  openmp/libomptarget/src/interface.cpp
  openmp/libomptarget/src/omptarget.cpp
  openmp/libomptarget/src/private.h
  openmp/libomptarget/test/mapping/present/target_data_at_exit.c

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