[flang][OpenMP] Add lowering support for task detach (#119128)

This PR adds lowering task detach to MLIR.

Author: NimishMishra

flang/lib/Lower/OpenMP/ClauseProcessor.cpp

@@ -458,6 +458,16 @@ bool ClauseProcessor::processPriority(
   return false;
 }
 
+bool ClauseProcessor::processDetach(mlir::omp::DetachClauseOps &result) const {
+  if (auto *clause = findUniqueClause<omp::clause::Detach>()) {
+    semantics::Symbol *sym = clause->v.sym();
+    mlir::Value symVal = converter.getSymbolAddress(*sym);
+    result.eventHandle = symVal;
+    return true;
+  }
+  return false;
+}
+
 bool ClauseProcessor::processProcBind(
     mlir::omp::ProcBindClauseOps &result) const {
   if (auto *clause = findUniqueClause<omp::clause::ProcBind>()) {

flang/lib/Lower/OpenMP/ClauseProcessor.h

@@ -90,6 +90,7 @@ class ClauseProcessor {
                           mlir::omp::ThreadLimitClauseOps &result) const;
   bool processUntied(mlir::omp::UntiedClauseOps &result) const;
 
+  bool processDetach(mlir::omp::DetachClauseOps &result) const;
   // 'Repeatable' clauses: They can appear multiple times in the clause list.
   bool processAligned(mlir::omp::AlignedClauseOps &result) const;
   bool processAllocate(mlir::omp::AllocateClauseOps &result) const;

flang/lib/Lower/OpenMP/OpenMP.cpp

@@ -1261,9 +1261,10 @@ static void genTaskClauses(lower::AbstractConverter &converter,
   cp.processMergeable(clauseOps);
   cp.processPriority(stmtCtx, clauseOps);
   cp.processUntied(clauseOps);
+  cp.processDetach(clauseOps);
   // TODO Support delayed privatization.
 
-  cp.processTODO<clause::Affinity, clause::Detach, clause::InReduction>(
+  cp.processTODO<clause::Affinity, clause::InReduction>(
       loc, llvm::omp::Directive::OMPD_task);
 }
 
@@ -2869,7 +2870,8 @@ static void genOMP(lower::AbstractConverter &converter, lower::SymMap &symTable,
         !std::holds_alternative<clause::UseDevicePtr>(clause.u) &&
         !std::holds_alternative<clause::InReduction>(clause.u) &&
         !std::holds_alternative<clause::Mergeable>(clause.u) &&
-        !std::holds_alternative<clause::TaskReduction>(clause.u)) {
+        !std::holds_alternative<clause::TaskReduction>(clause.u) &&
+        !std::holds_alternative<clause::Detach>(clause.u)) {
       std::string name =
           parser::ToUpperCaseLetters(llvm::omp::getOpenMPClauseName(clause.id));
       TODO(clauseLocation, name + " clause is not implemented yet");

flang/test/Lower/OpenMP/Todo/task_detach.f90 renamed to flang/test/Lower/OpenMP/task_detach.f90

@@ -1,12 +1,14 @@
 ! REQUIRES: openmp_runtime
-! RUN: %not_todo_cmd bbc -emit-fir %openmp_flags -fopenmp -fopenmp-version=50 -o - %s 2>&1 | FileCheck %s
-! RUN: %not_todo_cmd %flang_fc1 -emit-fir %openmp_flags -fopenmp -fopenmp-version=50 -o - %s 2>&1 | FileCheck %s
+! RUN: %flang_fc1 -emit-fir %openmp_flags -fopenmp -fopenmp-version=50 -o - %s | FileCheck %s
 
 !===============================================================================
 ! `detach` clause
 !===============================================================================
 
-! CHECK: not yet implemented: DETACH clause is not implemented yet
+!CHECK: omp.task detach(%[[EVENT_HANDLE:.*]] : !fir.ref<i64>) {
+!CHECK: fir.call @_QPfoo() fastmath<contract> : () -> ()
+!CHECK: omp.terminator
+!CHECK: }
 subroutine omp_task_detach()
   use omp_lib
   integer (kind=omp_event_handle_kind) :: event