[flang] Fix output type when emboxing intrinsic type to unlimited pol…

…ymorphic box

When emboxing an intrinsic type to a polymorphic descriptor, directly set its
type to `fir.class<none>`.

`fir.class<i32>` is not a real type used anywhere in lowering so make it right directly
avoid unnecessary convert op to `fir.class<none>`. Also `fir.class<i32>` would not be
recognized as unlimited polymorphic.

Reviewed By: jeanPerier, PeteSteinfeld

Differential Revision: https://reviews.llvm.org/D143888

flang/lib/Optimizer/Builder/FIRBuilder.cpp

@@ -511,8 +511,12 @@ mlir::Value fir::FirOpBuilder::createBox(mlir::Location loc,
   }
   mlir::Type boxTy = fir::BoxType::get(elementType);
   mlir::Value tdesc;
-  if (isPolymorphic)
+  if (isPolymorphic) {
+    if (!elementType.isa<mlir::NoneType, fir::RecordType>())
+      elementType = mlir::NoneType::get(elementType.getContext());
     boxTy = fir::ClassType::get(elementType);
+  }
+
   return exv.match(
       [&](const fir::ArrayBoxValue &box) -> mlir::Value {
         mlir::Value empty;

flang/test/Lower/polymorphic.f90

@@ -338,25 +338,20 @@ subroutine pass_trivial_to_up()
 
 ! CHECK-LABEL: func.func @_QMpolymorphic_testPpass_trivial_to_up() {
 ! CHECK: %[[CHAR:.*]] = fir.address_of(@_QQcl.{{.*}}) : !fir.ref<!fir.char<1,5>>
-! CHECK: %[[EMBOX:.*]] = fir.embox %[[CHAR]] : (!fir.ref<!fir.char<1,5>>) -> !fir.class<!fir.char<1,5>>
-! CHECK: %[[CONVERT:.*]] = fir.convert %[[EMBOX]] : (!fir.class<!fir.char<1,5>>) -> !fir.class<none>
-! CHECK: fir.call @_QMpolymorphic_testPup_input(%[[CONVERT]]) {{.*}} : (!fir.class<none>) -> ()
+! CHECK: %[[BOX_CHAR:.*]] = fir.embox %[[CHAR]] : (!fir.ref<!fir.char<1,5>>) -> !fir.class<none>
+! CHECK: fir.call @_QMpolymorphic_testPup_input(%[[BOX_CHAR]]) {{.*}} : (!fir.class<none>) -> ()
 
-! CHECK: %[[BOX_INT:.*]] = fir.embox %{{.*}} : (!fir.ref<i32>) -> !fir.class<i32>
-! CHECK: %[[UP:.*]] = fir.convert %[[BOX_INT]] : (!fir.class<i32>) -> !fir.class<none>
-! CHECK: fir.call @_QMpolymorphic_testPup_input(%[[UP]]) {{.*}} : (!fir.class<none>) -> ()
+! CHECK: %[[BOX_INT:.*]] = fir.embox %{{.*}} : (!fir.ref<i32>) -> !fir.class<none>
+! CHECK: fir.call @_QMpolymorphic_testPup_input(%[[BOX_INT]]) {{.*}} : (!fir.class<none>) -> ()
 
-! CHECK: %[[BOX_REAL:.*]] = fir.embox %{{.*}} : (!fir.ref<f32>) -> !fir.class<f32>
-! CHECK: %[[UP:.*]] = fir.convert %[[BOX_REAL]] : (!fir.class<f32>) -> !fir.class<none>
-! CHECK: fir.call @_QMpolymorphic_testPup_input(%[[UP]]) {{.*}} : (!fir.class<none>) -> ()
+! CHECK: %[[BOX_REAL:.*]] = fir.embox %{{.*}} : (!fir.ref<f32>) -> !fir.class<none>
+! CHECK: fir.call @_QMpolymorphic_testPup_input(%[[BOX_REAL]]) {{.*}} : (!fir.class<none>) -> ()
 
-! CHECK: %[[BOX_LOG:.*]] = fir.embox %{{.*}} : (!fir.ref<!fir.logical<4>>) -> !fir.class<!fir.logical<4>>
-! CHECK: %[[UP:.*]] = fir.convert %[[BOX_LOG]] : (!fir.class<!fir.logical<4>>) -> !fir.class<none>
-! CHECK: fir.call @_QMpolymorphic_testPup_input(%[[UP]]) {{.*}} : (!fir.class<none>) -> ()
+! CHECK: %[[BOX_LOG:.*]] = fir.embox %{{.*}} : (!fir.ref<!fir.logical<4>>) -> !fir.class<none>
+! CHECK: fir.call @_QMpolymorphic_testPup_input(%[[BOX_LOG]]) {{.*}} : (!fir.class<none>) -> ()
 
-! CHECK: %[[BOX_COMPLEX:.*]] = fir.embox %{{.*}} : (!fir.ref<!fir.complex<4>>) -> !fir.class<!fir.complex<4>>
-! CHECK: %[[UP:.*]] = fir.convert %[[BOX_COMPLEX]] : (!fir.class<!fir.complex<4>>) -> !fir.class<none>
-! CHECK: fir.call @_QMpolymorphic_testPup_input(%[[UP]]) {{.*}} : (!fir.class<none>) -> ()
+! CHECK: %[[BOX_COMPLEX:.*]] = fir.embox %{{.*}} : (!fir.ref<!fir.complex<4>>) -> !fir.class<none>
+! CHECK: fir.call @_QMpolymorphic_testPup_input(%[[BOX_COMPLEX]]) {{.*}} : (!fir.class<none>) -> ()
 
   subroutine assign_polymorphic_allocatable()
     type(p1), target :: t(10,20)