[flang] Add AllocatableInit functions for use in allocate lowering

`AllocatableInitIntrinsic`, `AllocatableInitCharacter` and
`AllocatableInitDerived` are meant to be used to initialize a
descriptor when it is instantiated and not to be used multiple
times in a scope.
Add `AllocatableInitDerivedForAllocate`, `AllocatableInitCharacterForAllocate`
and `AllocatableInitDerivedForAllocate` to be used for the allocation
in allocate statement.
These new functions are meant to be used on an initialized descriptor
and will return directly if the descriptor is allocated so the
error handling is done by the call to `AllocatableAllocate`.

Reviewed By: PeteSteinfeld

Differential Revision: https://reviews.llvm.org/D146290

1 files changed, 17 insertions, 0 deletions

diff --git a/flang/unittests/Runtime/Allocatable.cpp b/flang/unittests/Runtime/Allocatable.cpp
index 8e1ec467b89f..ed8e91932049 100644
--- a/flang/unittests/Runtime/Allocatable.cpp
+++ b/flang/unittests/Runtime/Allocatable.cpp
@@ -94,3 +94,20 @@ TEST(AllocatableTest, AllocateFromScalarSource) {
   EXPECT_EQ(*a->OffsetElement<float>(), 3.4F);
   a->Destroy();
 }
+
+TEST(AllocatableTest, DoubleAllocation) {
+  // CLASS(*), ALLOCATABLE :: r
+  // ALLOCATE(REAL::r)
+  auto r{createAllocatable(TypeCategory::Real, 4, 0)};
+  EXPECT_FALSE(r->IsAllocated());
+  EXPECT_TRUE(r->IsAllocatable());
+  RTNAME(AllocatableAllocate)(*r);
+  EXPECT_TRUE(r->IsAllocated());
+
+  // Make sure AllocatableInitIntrinsicForAllocate doesn't reset the decsriptor
+  // if it is allocated.
+  // ALLOCATE(INTEGER::r)
+  RTNAME(AllocatableInitIntrinsicForAllocate)
+  (*r, Fortran::common::TypeCategory::Integer, 4);
+  EXPECT_TRUE(r->IsAllocated());
+}