[flang][omp] Emit omp.workshare in frontend

Author: ivanradanov

flang/lib/Lower/OpenMP/OpenMP.cpp

@@ -1272,6 +1272,15 @@ static void genTaskwaitClauses(lower::AbstractConverter &converter,
       loc, llvm::omp::Directive::OMPD_taskwait);
 }
 
+static void genWorkshareClauses(lower::AbstractConverter &converter,
+                                semantics::SemanticsContext &semaCtx,
+                                lower::StatementContext &stmtCtx,
+                                const List<Clause> &clauses, mlir::Location loc,
+                                mlir::omp::WorkshareOperands &clauseOps) {
+  ClauseProcessor cp(converter, semaCtx, clauses);
+  cp.processNowait(clauseOps);
+}
+
 static void genTeamsClauses(lower::AbstractConverter &converter,
                             semantics::SemanticsContext &semaCtx,
                             lower::StatementContext &stmtCtx,
@@ -1897,6 +1906,22 @@ genTaskyieldOp(lower::AbstractConverter &converter, lower::SymMap &symTable,
   return converter.getFirOpBuilder().create<mlir::omp::TaskyieldOp>(loc);
 }
 
+static mlir::omp::WorkshareOp
+genWorkshareOp(lower::AbstractConverter &converter, lower::SymMap &symTable,
+           semantics::SemanticsContext &semaCtx, lower::pft::Evaluation &eval,
+           mlir::Location loc, const ConstructQueue &queue,
+           ConstructQueue::iterator item) {
+  lower::StatementContext stmtCtx;
+  mlir::omp::WorkshareOperands clauseOps;
+  genWorkshareClauses(converter, semaCtx, stmtCtx, item->clauses, loc, clauseOps);
+
+  return genOpWithBody<mlir::omp::WorkshareOp>(
+      OpWithBodyGenInfo(converter, symTable, semaCtx, loc, eval,
+                        llvm::omp::Directive::OMPD_workshare)
+          .setClauses(&item->clauses),
+      queue, item, clauseOps);
+}
+
 static mlir::omp::TeamsOp
 genTeamsOp(lower::AbstractConverter &converter, lower::SymMap &symTable,
            semantics::SemanticsContext &semaCtx, lower::pft::Evaluation &eval,
@@ -2309,10 +2334,7 @@ static void genOMPDispatch(lower::AbstractConverter &converter,
                   llvm::omp::getOpenMPDirectiveName(dir) + ")");
   // case llvm::omp::Directive::OMPD_workdistribute:
   case llvm::omp::Directive::OMPD_workshare:
-    // FIXME: Workshare is not a commonly used OpenMP construct, an
-    // implementation for this feature will come later. For the codes
-    // that use this construct, add a single construct for now.
-    genSingleOp(converter, symTable, semaCtx, eval, loc, queue, item);
+    genWorkshareOp(converter, symTable, semaCtx, eval, loc, queue, item);
     break;
   default:
     // Combined and composite constructs should have been split into a sequence