[Flang][OpenMP] Incorrect location information for OpenMP constructs/clauses

[kiranchandramohan]

@clementval reports that the location information for OpenMP constructs and clauses is incorrect.

In lowering, the getCurrentLocation function is used. getCurrentLocation refers to the location of the last Fortran construct. The same issue in OpenACC was fixed in https://reviews.llvm.org/D131659 using the genLocation function. A similar approach could be used for OpenMP as well.

Reproducer

For the following Fortran OpenMP program,

$ cat openmp_loc.f90 
subroutine sb(x,y)
  integer :: x, y
  !$omp parallel
      x = y
  !$omp end parallel
end subroutine

we get the following location information. As can be seen the location of the OpenMP construct is printed as loc1 (= line 1 column 1), this is incorrect.

$ ./bin/flang-new -fc1 -fopenmp  -emit-fir -mmlir --mlir-print-debuginfo openmp_loc.f90 -o -
#loc1 = loc("./openmp_loc.f90":1:1)
module attributes {fir.defaultkind = "a1c4d8i4l4r4", fir.kindmap = "", llvm.target_triple = "aarch64-unknown-linux-gnu"} {
  func.func @_QPsb(%arg0: !fir.ref<i32> {fir.bindc_name = "x"} loc("./openmp_loc.f90":1:1), %arg1: !fir.ref<i32> {fir.bindc_name = "y"} loc("./openmp_loc.f90":1:1)) {
    omp.parallel   {
      %0 = fir.load %arg1 : !fir.ref<i32> loc(#loc2)
      fir.store %0 to %arg0 : !fir.ref<i32> loc(#loc2)
      omp.terminator loc(#loc1)
    } loc(#loc1)
    return loc(#loc3)
  } loc(#loc1)
} loc(#loc0)
#loc0 = loc(unknown)
#loc2 = loc("./openmp_loc.f90":4:7)
#loc3 = loc("./openmp_loc.f90":6:1

[llvmbot]

@llvm/issue-subscribers-flang-ir

[llvmbot]

@llvm/issue-subscribers-good-first-issue

[llvmbot]

@llvm/issue-subscribers-bug

[llvmbot]

@llvm/issue-subscribers-openmp

[kiranchandramohan]

This issue is fixed by the above commit.