[flang][openmp] Add Lowering to omp mlir for workdistribute construct (#154378)

This PR adds lowering of workdistribute construct in flang to omp mlir dialect workdistribute op.

The work in this PR is c-p and updated from @ivanradanov commits from coexecute implementation:
flang_workdistribute_iwomp_2024

Author: skc7

flang/lib/Lower/OpenMP/OpenMP.cpp

@@ -534,6 +534,13 @@ static void processHostEvalClauses(lower::AbstractConverter &converter,
       cp.processCollapse(loc, eval, hostInfo->ops, hostInfo->iv);
       break;
 
+    case OMPD_teams_workdistribute:
+      cp.processThreadLimit(stmtCtx, hostInfo->ops);
+      [[fallthrough]];
+    case OMPD_target_teams_workdistribute:
+      cp.processNumTeams(stmtCtx, hostInfo->ops);
+      break;
+
     // Standalone 'target' case.
     case OMPD_target: {
       processSingleNestedIf(
@@ -2820,6 +2827,17 @@ genTeamsOp(lower::AbstractConverter &converter, lower::SymMap &symTable,
       queue, item, clauseOps);
 }
 
+static mlir::omp::WorkdistributeOp genWorkdistributeOp(
+    lower::AbstractConverter &converter, lower::SymMap &symTable,
+    semantics::SemanticsContext &semaCtx, lower::pft::Evaluation &eval,
+    mlir::Location loc, const ConstructQueue &queue,
+    ConstructQueue::const_iterator item) {
+  return genOpWithBody<mlir::omp::WorkdistributeOp>(
+      OpWithBodyGenInfo(converter, symTable, semaCtx, loc, eval,
+                        llvm::omp::Directive::OMPD_workdistribute),
+      queue, item);
+}
+
 //===----------------------------------------------------------------------===//
 // Code generation functions for the standalone version of constructs that can
 // also be a leaf of a composite construct
@@ -3459,7 +3477,10 @@ static void genOMPDispatch(lower::AbstractConverter &converter,
   case llvm::omp::Directive::OMPD_unroll:
     genUnrollOp(converter, symTable, stmtCtx, semaCtx, eval, loc, queue, item);
     break;
-  // case llvm::omp::Directive::OMPD_workdistribute:
+  case llvm::omp::Directive::OMPD_workdistribute:
+    newOp = genWorkdistributeOp(converter, symTable, semaCtx, eval, loc, queue,
+                                item);
+    break;
   case llvm::omp::Directive::OMPD_workshare:
     newOp = genWorkshareOp(converter, symTable, stmtCtx, semaCtx, eval, loc,
                            queue, item);

flang/test/Lower/OpenMP/workdistribute.f90

@@ -0,0 +1,30 @@
+! RUN: %flang_fc1 -emit-hlfir -fopenmp -fopenmp-version=60 %s -o - | FileCheck %s
+
+! CHECK-LABEL: func @_QPtarget_teams_workdistribute
+subroutine target_teams_workdistribute()
+  integer :: aa(10), bb(10)
+  ! CHECK: omp.target
+  ! CHECK: omp.teams
+  ! CHECK: omp.workdistribute
+  !$omp target teams workdistribute
+  aa = bb
+  ! CHECK: omp.terminator
+  ! CHECK: omp.terminator
+  ! CHECK: omp.terminator
+  !$omp end target teams workdistribute
+end subroutine target_teams_workdistribute
+
+! CHECK-LABEL: func @_QPteams_workdistribute
+subroutine teams_workdistribute()
+  use iso_fortran_env
+  real(kind=real32) :: a
+  real(kind=real32), dimension(10) :: x
+  real(kind=real32), dimension(10) :: y
+  ! CHECK: omp.teams
+  ! CHECK: omp.workdistribute
+  !$omp teams workdistribute
+  y = a * x + y
+  ! CHECK: omp.terminator
+  ! CHECK: omp.terminator
+  !$omp end teams workdistribute
+end subroutine teams_workdistribute