[Flang][OpenMP][MLIR] Check for presence of Box type before emitting store in MapInfoFinalization pass

flang/lib/Optimizer/OpenMP/MapInfoFinalization.cpp

@@ -153,7 +153,15 @@ class MapInfoFinalizationPass
     builder.setInsertionPointToStart(allocaBlock);
     auto alloca = builder.create<fir::AllocaOp>(loc, descriptor.getType());
     builder.restoreInsertionPoint(insPt);
-    builder.create<fir::StoreOp>(loc, descriptor, alloca);
+    // We should only emit a store if the passed in data is present, it is
+    // possible a user passes in no argument to an optional parameter, in which
+    // case we cannot store or we'll segfault on the emitted memcpy.
+    auto isPresent =
+        builder.create<fir::IsPresentOp>(loc, builder.getI1Type(), descriptor);
+    builder.genIfOp(loc, {}, isPresent, false)
+        .genThen(
+            [&]() { builder.create<fir::StoreOp>(loc, descriptor, alloca); })
+        .end();
     return slot = alloca;
   }
 

flang/test/Lower/OpenMP/optional-argument-map.f90

@@ -0,0 +1,27 @@
+!RUN: %flang_fc1 -emit-hlfir -fopenmp %s -o - | FileCheck %s
+
+module foo
+    implicit none
+    contains
+    subroutine test(I,A)
+      implicit none
+      real(4), optional, intent(inout) :: A(:)
+      integer(kind=4), intent(in) :: I
+
+     !$omp target data map(to: A) if (I>0)
+     !$omp end target data
+
+    end subroutine test
+end module foo
+
+! CHECK-LABEL:   func.func @_QMfooPtest(
+! CHECK-SAME:                           %[[VAL_0:.*]]: !fir.ref<i32> {fir.bindc_name = "i"},
+! CHECK-SAME:                           %[[VAL_1:.*]]: !fir.box<!fir.array<?xf32>> {fir.bindc_name = "a", fir.optional}) {
+! CHECK:           %[[VAL_2:.*]] = fir.alloca !fir.box<!fir.array<?xf32>>
+! CHECK:           %[[VAL_3:.*]]:2 = hlfir.declare %[[VAL_1]] dummy_scope %{{.*}} {fortran_attrs = #fir.var_attrs<intent_inout, optional>, uniq_name = "_QMfooFtestEa"} : (!fir.box<!fir.array<?xf32>>, !fir.dscope) -> (!fir.box<!fir.array<?xf32>>, !fir.box<!fir.array<?xf32>>)
+! CHECK:           %{{.*}} = fir.is_present %{{.*}}#1 : (!fir.box<!fir.array<?xf32>>) -> i1
+! CHECK:           %{{.*}}:5 = fir.if %{{.*}}
+! CHECK:           %[[VAL_4:.*]] = fir.is_present %[[VAL_3]]#1 : (!fir.box<!fir.array<?xf32>>) -> i1
+! CHECK:           fir.if %[[VAL_4]] {
+! CHECK:             fir.store %[[VAL_3]]#1 to %[[VAL_2]] : !fir.ref<!fir.box<!fir.array<?xf32>>>
+! CHECK:           }

offload/test/offloading/fortran/optional-mapped-arguments.f90

@@ -0,0 +1,36 @@
+! OpenMP offloading test that checks we do not cause a segfault when mapping
+! optional function arguments (present or otherwise). No results requiring
+! checking other than that the program compiles and runs to completion with no
+! error.
+! REQUIRES: flang, amdgpu
+
+! RUN: %libomptarget-compile-fortran-run-and-check-generic
+module foo
+    implicit none
+    contains
+    subroutine test(I,A)
+        implicit none
+        real(4), optional, intent(inout) :: A(:)
+        integer(kind=4), intent(in) :: I
+
+        !$omp target data map(to: A) if (I>0)
+        !$omp end target data
+
+        !$omp target enter data map(to:A) if (I>0)
+
+        !$omp target exit data map(from:A) if (I>0)
+    end subroutine test
+end module foo
+
+program main
+    use foo
+    implicit none
+    real :: array(10)
+    call test(0)
+    call test(1)
+    call test(0, array)
+    call test(1, array)
+    print *, "PASSED"
+end program main
+
+! CHECK: PASSED