[PATCH] D84192: [OpenMP5.0] map item can be non-contiguous for target update

[Chi Chun Chen via Phabricator via cfe-commits]

cchen created this revision.
cchen added a reviewer: ABataev.
Herald added subscribers: cfe-commits, sstefan1, guansong, yaxunl.
Herald added a reviewer: jdoerfert.
Herald added a project: clang.

In order not to modify the `tgt_target_data_update` information but still be
able to pass the extra information for non-contiguous map item (offset,
count, and stride for each dimension), this patch overload `arg` when
the maptype is set as `OMP_MAP_DESCRIPTOR`. The origin `arg` is for
passing the pointer information, however, the overloaded `arg` is an
array of descriptor_dim:

struct descriptor_dim {

  int64_t offset;
  int64_t count;
  int64_t stride

};

and the array size is the same as dimension size. In addition, since we
have count and stride information in descriptor_dim, we can replace/overload the
`arg_size` parameter by using dimension size.

For supporting `stride` in array section, we use a dummy dimension in
descriptor to store the unit size. The formula for counting the stride
in dimension D_n: `unit size * (D_0 * D_1 ... * D_n-1) * D_n.stride`.

Demonstrate how it works:

  double arr[3][4][5];
  
  D0: { offset = 0, count = 1, stride = 8 }                                // offset, count, dimension size always be 0, 1, 1 for this extra dimension, stride is the unit size
  D1: { offset = 0, count = 2, stride = 8 * 1 * 2 = 16 }                   // stride = unit size * (product of dimension size of D0) * D1.stride = 4 * 1 * 2 = 8
  D2: { offset = 2, count = 2, stride = 8 * (1 * 5) * 1 = 40  }            // stride = unit size * (product of dimension size of D0, D1) * D2.stride = 4 * 5 * 1 = 20
  D3: { offset = 0, count = 2, stride = 8 * (1 * 5 * 4) * 2 = 320 }        // stride = unit size * (product of dimension size of D0, D1, D2) * D3.stride = 4 * 25 * 2 = 200
  
  // X here means we need to offload this data, therefore, runtime will transfer
  // data from offset 80, 96, 120, 136, 400, 416, 440, 456
  // Runtime patch: https://reviews.llvm.org/D82245
  // OOOOO OOOOO OOOOO
  // OOOOO OOOOO OOOOO
  // XOXOO OOOOO XOXOO
  // XOXOO OOOOO XOXOO


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D84192

Files:
  clang/include/clang/AST/OpenMPClause.h
  clang/include/clang/Basic/DiagnosticSemaKinds.td
  clang/lib/CodeGen/CGOpenMPRuntime.cpp
  clang/lib/CodeGen/CGOpenMPRuntime.h
  clang/lib/Sema/SemaOpenMP.cpp
  clang/lib/Serialization/ASTReader.cpp
  clang/lib/Serialization/ASTWriter.cpp
  clang/test/OpenMP/target_update_ast_print.cpp
  clang/test/OpenMP/target_update_codegen.cpp
  clang/test/OpenMP/target_update_messages.cpp
  clang/test/OpenMP/target_update_to_messages.cpp

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