[flang][hlfir] Use complete form of DesignateOp for im/re array designators.

[vzakhari]

Summary

With this change, the lowering provides full slice triples for
designators like ...%array_comp%im/re, so that the codegen
does not have to figure it out for the array_comp.
Basically, ...%array_comp%im/re is lowered the same way
as ...%array_comp(:,:,...)%im/re.

[jeanPerier]

LGTM, thanks!

flang/lib/Lower/ConvertExprToHLFIR.cpp

if (partInfo.base.value().isArray()) {
       // the one of the base. Compute it here. Note that the lower bounds of the
       // base are not the ones of the resulting reference (that are default
       // ones).
       partInfo.resultShape = hlfir::genShape(loc, getBuilder(), *partInfo.base);
       assert(!partInfo.componentShape &&
              "Fortran designators can only have one ranked part");
       return changeElementType(baseType, componentBaseType);
     }
+
+    if (partInfo.complexPart && partInfo.componentShape) {
+      // Treat ...array_comp%im/re as ...array_comp(:,:,...)%im/re
+      // so that the codegen has the full slice triples for the component
+      // readily available.
+      fir::FirOpBuilder &builder = getBuilder();
+      mlir::Type idxTy = builder.getIndexType();
+      mlir::Value one = builder.createIntegerConstant(loc, idxTy, 1);
+
+      llvm::SmallVector<mlir::Value> resultExtents;
+      // Collect <lb, ub> pairs from the component shape.
+      auto bounds = hlfir::genBounds(loc, builder, partInfo.componentShape);
+      for (auto &boundPair : bounds) {
+        // The default subscripts are <lb, ub, 1>:
+        partInfo.subscripts.emplace_back(hlfir::DesignateOp::Triplet{
+            boundPair.first, boundPair.second, one});
+        auto extentValue = builder.genExtentFromTriplet(
+            loc, boundPair.first, boundPair.second, one, idxTy);
+        resultExtents.push_back(extentValue);
+      }
+      // The result shape is: <max((ub - lb + 1) / 1, 0), ...>.
+      partInfo.resultShape = builder.genShape(loc, resultExtents);
+      return componentBaseType;
+    }
+
     // scalar%array_comp or scalar%scalar. In any case the shape of this
     // part-ref is coming from the component.
     partInfo.resultShape = partInfo.componentShape;
     partInfo.componentShape = {};
     return componentBaseType;
   }
 
   // Returns the <BaseType, ComponentType> pair, computes partInfo.base,

flang/test/Lower/HLFIR/designators-component-ref.f90

type t_array_lbs
   integer :: scalar_i
   real :: array_comp_lbs(2:11,3:22)
 end type
 
 type t_array_char
   integer :: scalar_i
   character(5) :: array_char_comp(10,20)
 end type
+
+type t_complex
+   complex :: array_comp(2:11,3:22)
+end type
 end module
 
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 !                            Test scalar bases                                 !
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
 subroutine test_scalar(a)
   use comp_ref

 ! CHECK:  %[[VAL_14:.*]] = hlfir.designate %[[VAL_3]]#0 (%[[VAL_9]]:%[[VAL_10]]:%[[VAL_11]])  shape %[[VAL_13]] : (!fir.ref<!fir.array<100x!fir.type<_QMcomp_refTt_array{scalar_i:i32,array_comp:!fir.array<10x20xf32>}>>>, index, index, index, !fir.shape<1>) -> !fir.box<!fir.array<10x!fir.type<_QMcomp_refTt_array{scalar_i:i32,array_comp:!fir.array<10x20xf32>}>>>
 ! CHECK:  %[[VAL_15:.*]] = arith.constant 10 : index
 ! CHECK:  %[[VAL_16:.*]] = arith.constant 20 : index
 ! CHECK:  %[[VAL_17:.*]] = fir.shape %[[VAL_15]], %[[VAL_16]] : (index, index) -> !fir.shape<2>
 ! CHECK:  %[[VAL_18:.*]] = arith.constant 4 : index
 ! CHECK:  %[[VAL_19:.*]] = arith.constant 5 : index
 ! CHECK:  %[[VAL_20:.*]] = hlfir.designate %[[VAL_14]]{"array_comp"} <%[[VAL_17]]> (%[[VAL_18]], %[[VAL_19]])  shape %[[VAL_13]] : (!fir.box<!fir.array<10x!fir.type<_QMcomp_refTt_array{scalar_i:i32,array_comp:!fir.array<10x20xf32>}>>>, !fir.shape<2>, index, index, !fir.shape<1>) -> !fir.box<!fir.array<10xf32>>
 end subroutine
+
+subroutine test_scalar_array_complex_chain(a)
+  use comp_ref
+  type(t_complex) :: a
+  print *, a%array_comp%im
+! CHECK-LABEL:   func.func @_QPtest_scalar_array_complex_chain(
+! CHECK:           %[[VAL_1:.*]]:2 = hlfir.declare %[[VAL_0]] {uniq_name = "_QFtest_scalar_array_complex_chainEa"} : (!fir.ref<!fir.type<_QMcomp_refTt_complex{array_comp:!fir.array<10x20x!fir.complex<4>>}>>) -> (!fir.ref<!fir.type<_QMcomp_refTt_complex{array_comp:!fir.array<10x20x!fir.complex<4>>}>>, !fir.ref<!fir.type<_QMcomp_refTt_complex{array_comp:!fir.array<10x20x!fir.complex<4>>}>>)
+! CHECK:           %[[VAL_7:.*]] = arith.constant 10 : index
+! CHECK:           %[[VAL_8:.*]] = arith.constant 20 : index
+! CHECK:           %[[VAL_9:.*]] = arith.constant 2 : index
+! CHECK:           %[[VAL_10:.*]] = arith.constant 3 : index
+! CHECK:           %[[VAL_11:.*]] = fir.shape_shift %[[VAL_9]], %[[VAL_7]], %[[VAL_10]], %[[VAL_8]] : (index, index, index, index) -> !fir.shapeshift<2>
+! CHECK:           %[[VAL_12:.*]] = arith.constant 1 : index
+! CHECK:           %[[VAL_13:.*]] = arith.constant 1 : index
+! CHECK:           %[[VAL_14:.*]] = arith.addi %[[VAL_9]], %[[VAL_7]] : index
+! CHECK:           %[[VAL_15:.*]] = arith.subi %[[VAL_14]], %[[VAL_13]] : index
+! CHECK:           %[[VAL_16:.*]] = arith.addi %[[VAL_10]], %[[VAL_8]] : index
+! CHECK:           %[[VAL_17:.*]] = arith.subi %[[VAL_16]], %[[VAL_13]] : index
+! CHECK:           %[[VAL_18:.*]] = arith.constant 0 : index
+! CHECK:           %[[VAL_19:.*]] = arith.subi %[[VAL_15]], %[[VAL_9]] : index
+! CHECK:           %[[VAL_20:.*]] = arith.addi %[[VAL_19]], %[[VAL_12]] : index
+! CHECK:           %[[VAL_21:.*]] = arith.divsi %[[VAL_20]], %[[VAL_12]] : index
+! CHECK:           %[[VAL_22:.*]] = arith.cmpi sgt, %[[VAL_21]], %[[VAL_18]] : index
+! CHECK:           %[[VAL_23:.*]] = arith.select %[[VAL_22]], %[[VAL_21]], %[[VAL_18]] : index
+! CHECK:           %[[VAL_24:.*]] = arith.constant 0 : index
+! CHECK:           %[[VAL_25:.*]] = arith.subi %[[VAL_17]], %[[VAL_10]] : index
+! CHECK:           %[[VAL_26:.*]] = arith.addi %[[VAL_25]], %[[VAL_12]] : index
+! CHECK:           %[[VAL_27:.*]] = arith.divsi %[[VAL_26]], %[[VAL_12]] : index
+! CHECK:           %[[VAL_28:.*]] = arith.cmpi sgt, %[[VAL_27]], %[[VAL_24]] : index
+! CHECK:           %[[VAL_29:.*]] = arith.select %[[VAL_28]], %[[VAL_27]], %[[VAL_24]] : index
+! CHECK:           %[[VAL_30:.*]] = fir.shape %[[VAL_23]], %[[VAL_29]] : (index, index) -> !fir.shape<2>
+! CHECK:           %[[VAL_31:.*]] = hlfir.designate %[[VAL_1]]#0{"array_comp"} <%[[VAL_11]]> (%[[VAL_9]]:%[[VAL_15]]:%[[VAL_12]], %[[VAL_10]]:%[[VAL_17]]:%[[VAL_12]]) imag shape %[[VAL_30]] : (!fir.ref<!fir.type<_QMcomp_refTt_complex{array_comp:!fir.array<10x20x!fir.complex<4>>}>>, !fir.shapeshift<2>, index, index, index, index, index, index, !fir.shape<2>) -> !fir.box<!fir.array<10x20xf32>>
+end subroutine