[flang] Fix output type when emboxing intrinsic type to unlimited polymorphic box

[clementval]

Summary

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.

[jeanPerier]

flang/lib/Optimizer/Builder/FIRBuilder.cpp

515

I think the same could apply with characters that are not covered by isa_trivial. It's probably safer to reverse the logic: everything that is not None or RecordType should be turned into None.

[clementval]

Reverse condition to handle char as well

[clementval]

flang/lib/Optimizer/Builder/FIRBuilder.cpp

515

Makes sense. Updated.

[PeteSteinfeld]

All builds and tests correctly and looks good.

[jeanPerier]

LGTM

[clementval]

This needs a bit more work to not override some important part of the type fir.array<i32> -> none instead of fir.array<none>. I'm preparing a more complete patch to deal with all the cases.

flang/lib/Optimizer/Builder/FIRBuilder.cpp

mlir::Value fir::FirOpBuilder::createBox(mlir::Location loc,
   auto elementType = fir::dyn_cast_ptrEleTy(itemAddr.getType());
   if (!elementType) {
     mlir::emitError(loc, "internal: expected a memory reference type ")
         << itemAddr.getType();
     llvm_unreachable("not a memory reference type");
   }
   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;
         mlir::ValueRange emptyRange;
         mlir::Value s = createShape(loc, exv);
         return create<fir::EmboxOp>(loc, boxTy, itemAddr, s, /*slice=*/empty,
                                     /*typeparams=*/emptyRange,
                                     isPolymorphic ? box.getSourceBox() : tdesc);

flang/test/Lower/polymorphic.f90

subroutine pass_trivial_to_up()
     call up_input(1)
     call up_input(2.5)
     call up_input(.true.)
     call up_input((-1.0,3))
   end subroutine
 
 ! 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_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_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_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_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_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<none>
+! CHECK: fir.call @_QMpolymorphic_testPup_input(%[[BOX_INT]]) {{.*}} : (!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<none>
+! CHECK: fir.call @_QMpolymorphic_testPup_input(%[[BOX_LOG]]) {{.*}} : (!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)
     class(p1), allocatable :: c(:,:)
     c = t
   end subroutine
 
 ! CHECK-LABEL: func.func @_QMpolymorphic_testPassign_polymorphic_allocatable() {