[flang] Recognize unused dummy arguments during lowering with HLFIR.

[vzakhari]

Summary

So far we've relied on AllocaOp to represent the dummy arguments
not declared for the current entry. With HLFIR we have to account
for hlfir::DeclareOp.

[jeanPerier]

Looks good, thanks!

flang/lib/Lower/ConvertVariable.cpp

static void deallocateIntentOut(Fortran::lower::AbstractConverter &converter,
   const Fortran::semantics::Symbol &sym = var.getSymbol();
   if (Fortran::semantics::IsDummy(sym) &&
       Fortran::semantics::IsIntentOut(sym) &&
       Fortran::semantics::IsAllocatable(sym)) {
     fir::ExtendedValue extVal = converter.getSymbolExtendedValue(sym, &symMap);
     if (auto mutBox = extVal.getBoxOf<fir::MutableBoxValue>()) {
       // The dummy argument is not passed in the ENTRY so it should not be
       // deallocated.
-      if (mlir::Operation *op = mutBox->getAddr().getDefiningOp())
-        if (mlir::isa<fir::AllocaOp>(op))
+      if (mlir::Operation *op = mutBox->getAddr().getDefiningOp()) {
+        if (auto declOp = mlir::dyn_cast<hlfir::DeclareOp>(op))
+          op = declOp.getMemref().getDefiningOp();
+        if (op && mlir::isa<fir::AllocaOp>(op))
           return;
+      }
       mlir::Location loc = converter.getCurrentLocation();
       fir::FirOpBuilder &builder = converter.getFirOpBuilder();
       auto genDeallocateWithTypeDesc = [&]() {
         if (mutBox->isDerived() || mutBox->isPolymorphic() ||
             mutBox->isUnlimitedPolymorphic()) {
           mlir::Value isAlloc = fir::factory::genIsAllocatedOrAssociatedTest(
               builder, loc, *mutBox);
           builder.genIfThen(loc, isAlloc)

flang/test/HLFIR/dummy_deallocation.f90

+! RUN: bbc -emit-fir -hlfir %s -o - | FileCheck %s
+! RUN: bbc -emit-fir %s -o - | FileCheck %s
+
+! Test that the intent(out) allocatable dummy argument
+! is not deallocated in entry SUB_B.
+
+! CHECK-LABEL: func.func @_QPsub_a
+! CHECK: fir.freemem
+
+! CHECK-LABEL: func.func @_QPsub_b
+! CHECK-NOT: fir.freemem
+SUBROUTINE SUB_A(A)
+  INTEGER, INTENT(out), ALLOCATABLE, DIMENSION (:) :: A
+  RETURN
+  ENTRY SUB_B
+END SUBROUTINE SUB_A