[Flang][OpenMP] Only access the MapType if it is specified

[kiranchandramohan]

Summary

Fixes #63638

flang/lib/Lower/OpenMP.cpp

auto checkType = [](mlir::Location location, mlir::Type type) {
     if (auto refType = type.dyn_cast<fir::ReferenceType>())
       type = refType.getElementType();
     if (auto boxType = type.dyn_cast_or_null<fir::BoxType>())
       if (!boxType.getElementType().isa<fir::PointerType>())
         TODO(location, "OMPD_target_data MapOperand BoxType");
   };
 
   auto addMapClause = [&](const auto &mapClause, mlir::Location &location) {
-    auto mapType = std::get<Fortran::parser::OmpMapType::Type>(
-        std::get<std::optional<Fortran::parser::OmpMapType>>(mapClause->v.t)
-            ->t);
+    const auto &oMapType =
+        std::get<std::optional<Fortran::parser::OmpMapType>>(mapClause->v.t);
     llvm::omp::OpenMPOffloadMappingFlags mapTypeBits =
         llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_NONE;
+    // If the map type is specified, then process it else Tofrom is the default.
+    if (oMapType) {
+      const Fortran::parser::OmpMapType::Type &mapType =
+          std::get<Fortran::parser::OmpMapType::Type>(oMapType->t);
       switch (mapType) {
       case Fortran::parser::OmpMapType::Type::To:
         mapTypeBits |= llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_TO;
         break;
       case Fortran::parser::OmpMapType::Type::From:
         mapTypeBits |= llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_FROM;
         break;
       case Fortran::parser::OmpMapType::Type::Tofrom:
         mapTypeBits |= llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_TO |
                        llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_FROM;
         break;
       case Fortran::parser::OmpMapType::Type::Alloc:
       case Fortran::parser::OmpMapType::Type::Release:
-      // alloc and release is the default map_type for the Target Data Ops, i.e.
-      // if no bits for map_type is supplied then alloc/release is implicitly
-      // assumed based on the target directive. Default value for Target Data
-      // and Enter Data is alloc and for Exit Data it is release.
+        // alloc and release is the default map_type for the Target Data Ops,
+        // i.e. if no bits for map_type is supplied then alloc/release is
+        // implicitly assumed based on the target directive. Default value for
+        // Target Data and Enter Data is alloc and for Exit Data it is release.
         break;
       case Fortran::parser::OmpMapType::Type::Delete:
         mapTypeBits |= llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_DELETE;
       }
+
       if (std::get<std::optional<Fortran::parser::OmpMapType::Always>>(
-            std::get<std::optional<Fortran::parser::OmpMapType>>(mapClause->v.t)
-                ->t)
-            .has_value())
+              oMapType->t))
         mapTypeBits |= llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_ALWAYS;
+    } else {
+      mapTypeBits |= llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_TO |
+                     llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_FROM;
+    }
 
     // TODO: Add support MapTypeModifiers close, mapper, present, iterator
 
     mlir::IntegerAttr mapTypeAttr = firOpBuilder.getIntegerAttr(
         firOpBuilder.getI64Type(),
         static_cast<
             std::underlying_type_t<llvm::omp::OpenMPOffloadMappingFlags>>(
             mapTypeBits));

flang/test/Lower/OpenMP/target.f90

!$omp target data map(tofrom: a)
       !CHECK: %[[VAL_5:.*]] = fir.coordinate_of %[[VAL_0]], %[[VAL_4]] : (!fir.ref<!fir.array<1024xi32>>, i64) -> !fir.ref<i32>
       !CHECK: fir.store %[[VAL_1]] to %[[VAL_5]] : !fir.ref<i32>
       a(1) = 10
    !CHECK: omp.terminator
    !$omp end target data
    !CHECK: }
 end subroutine omp_target_data
 
+!CHECK-LABEL: func.func @_QPomp_target_data_mt
+subroutine omp_target_data_mt
+   integer :: a(1024)
+   integer :: b(1024)
+   !CHECK: %[[VAR_A:.*]] = fir.alloca !fir.array<1024xi32> {bindc_name = "a", uniq_name = "_QFomp_target_data_mtEa"}
+   !CHECK: %[[VAR_B:.*]] = fir.alloca !fir.array<1024xi32> {bindc_name = "b", uniq_name = "_QFomp_target_data_mtEb"}
+   !CHECK: omp.target_data   map((tofrom -> %[[VAR_A]] : !fir.ref<!fir.array<1024xi32>>))
+   !$omp target data map(a)
+   !CHECK: omp.terminator
+   !$omp end target data
+   !CHECK: }
+   !CHECK: omp.target_data   map((always, from -> %[[VAR_B]] : !fir.ref<!fir.array<1024xi32>>))
+   !$omp target data map(always, from : b)
+   !CHECK: omp.terminator
+   !$omp end target data
+   !CHECK: }
+end subroutine omp_target_data_mt
+
 !===============================================================================
 ! Target with region
 !===============================================================================
 
 !CHECK-LABEL: func.func @_QPomp_target() {
 subroutine omp_target
    !CHECK: %[[VAL_0:.*]] = fir.alloca !fir.array<1024xi32> {bindc_name = "a", uniq_name = "_QFomp_targetEa"}
    integer :: a(1024)