[flang] implement sizeof lowering for polymorphic entities (#84498)

For non polymorphic entities, semantics knows the type size and rewrite
sizeof to `"cst element size" * size(x)`.

Lowering has to deal with the polymorphic case where the type size must
be retrieved from the descriptor (note that the lowering implementation
would work with any entity, polymorphic on not, it is just not used for
the non polymorphic cases).

flang/include/flang/Optimizer/Builder/IntrinsicCall.h

@@ -338,6 +338,7 @@ struct IntrinsicLibrary {
   mlir::Value genSign(mlir::Type, llvm::ArrayRef<mlir::Value>);
   mlir::Value genSind(mlir::Type, llvm::ArrayRef<mlir::Value>);
   fir::ExtendedValue genSize(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
+  fir::ExtendedValue genSizeOf(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   mlir::Value genSpacing(mlir::Type resultType,
                          llvm::ArrayRef<mlir::Value> args);
   fir::ExtendedValue genSpread(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);

flang/lib/Optimizer/Builder/IntrinsicCall.cpp

@@ -567,6 +567,10 @@ static constexpr IntrinsicHandler handlers[]{
        {"dim", asAddr, handleDynamicOptional},
        {"kind", asValue}}},
      /*isElemental=*/false},
+    {"sizeof",
+     &I::genSizeOf,
+     {{{"a", asBox}}},
+     /*isElemental=*/false},
     {"sleep", &I::genSleep, {{{"seconds", asValue}}}, /*isElemental=*/false},
     {"spacing", &I::genSpacing},
     {"spread",
@@ -5946,6 +5950,20 @@ IntrinsicLibrary::genSize(mlir::Type resultType,
       .getResults()[0];
 }
 
+// SIZEOF
+fir::ExtendedValue
+IntrinsicLibrary::genSizeOf(mlir::Type resultType,
+                            llvm::ArrayRef<fir::ExtendedValue> args) {
+  assert(args.size() == 1);
+  mlir::Value box = fir::getBase(args[0]);
+  mlir::Value eleSize = builder.create<fir::BoxEleSizeOp>(loc, resultType, box);
+  if (!fir::isArray(args[0]))
+    return eleSize;
+  mlir::Value arraySize = builder.createConvert(
+      loc, resultType, fir::runtime::genSize(builder, loc, box));
+  return builder.create<mlir::arith::MulIOp>(loc, eleSize, arraySize);
+}
+
 // TAND
 mlir::Value IntrinsicLibrary::genTand(mlir::Type resultType,
                                       llvm::ArrayRef<mlir::Value> args) {

flang/test/Lower/Intrinsics/sizeof.f90

@@ -0,0 +1,23 @@
+! Test SIZEOF lowering for polymorphic entities.
+! RUN: bbc -emit-hlfir --polymorphic-type -o - %s | FileCheck %s
+
+integer(8) function test1(x)
+  class(*) :: x
+  test1 = sizeof(x)
+end function
+! CHECK-LABEL:   func.func @_QPtest1(
+! CHECK:           %[[VAL_3:.*]]:2 = hlfir.declare %{{.*}} {uniq_name = "_QFtest1Ex"} : (!fir.class<none>) -> (!fir.class<none>, !fir.class<none>)
+! CHECK:           %[[VAL_4:.*]] = fir.box_elesize %[[VAL_3]]#1 : (!fir.class<none>) -> i64
+! CHECK:           hlfir.assign %[[VAL_4]] to %{{.*}} : i64, !fir.ref<i64>
+
+integer(8) function test2(x)
+  class(*) :: x(:, :)
+  test2 = sizeof(x)
+end function
+! CHECK-LABEL:   func.func @_QPtest2(
+! CHECK:           %[[VAL_3:.*]]:2 = hlfir.declare %{{.*}} {uniq_name = "_QFtest2Ex"} : (!fir.class<!fir.array<?x?xnone>>) -> (!fir.class<!fir.array<?x?xnone>>, !fir.class<!fir.array<?x?xnone>>)
+! CHECK:           %[[VAL_4:.*]] = fir.box_elesize %[[VAL_3]]#1 : (!fir.class<!fir.array<?x?xnone>>) -> i64
+! CHECK:           %[[VAL_7:.*]] = fir.convert %[[VAL_3]]#1 : (!fir.class<!fir.array<?x?xnone>>) -> !fir.box<none>
+! CHECK:           %[[VAL_9:.*]] = fir.call @_FortranASize(%[[VAL_7]], %{{.*}}, %{{.*}}) fastmath<contract> : (!fir.box<none>, !fir.ref<i8>, i32) -> i64
+! CHECK:           %[[VAL_10:.*]] = arith.muli %[[VAL_4]], %[[VAL_9]] : i64
+! CHECK:           hlfir.assign %[[VAL_10]] to %{{.*}} : i64, !fir.ref<i64>