[Mlir-commits] [mlir] [flang][OpenMP] Translate OpenMP scopes when compiling for target device (PR #130078)

[Sergio Afonso]

================
@@ -5315,6 +5320,46 @@ convertTargetOpsInNest(Operation *op, llvm::IRBuilderBase &builder,
               return WalkResult::interrupt();
             return WalkResult::skip();
           }
+
+          // Non-target ops might nest target-related ops, therefore, we
+          // translate them as non-OpenMP scopes. Translating them is needed by
+          // nested target-related ops since they might need LLVM values defined
+          // in their parent non-target ops.
+          if (isa<omp::OpenMPDialect>(oper->getDialect()) &&
+              oper->getParentOfType<LLVM::LLVMFuncOp>() &&
+              !oper->getRegions().empty()) {
----------------
skatrak wrote:

I was thinking of something like this (since `omp.threadprivate` seems to be the only non map-related OpenMP op that returns some value at the moment):
```f90
module test
  implicit none
  integer :: n
  
  !$omp threadprivate(n)
  
  contains
  subroutine foo(x)
    integer, intent(inout) :: x(10)

    !$omp target map(tofrom: x(1:n))
    call bar(x)
    !$omp end target
  end subroutine
end module
```
Lowering it to MLIR for the device results in the following sequence of operations:
```mlir
%3 = omp.threadprivate ...
%4 = fir.declare %3
%13 = omp.map.info var_ptr(%4 : !fir.ref<i32>, i32) ...
omp.target map_entries(%13 -> %arg2 ...) {
  ...
}
```

https://github.com/llvm/llvm-project/pull/130078