[flang][optimizer] support aggregate types inside tuple and record type

[jeanPerier]

Summary

Allow fir.box type to be a member of a tuple<> or fir.type<>, in which
case it should be ensured it should be ensured the fir.box member is not
translate to the struct type of a Fortran runtime descriptor, and not a
pointer to it.

FIR type translation was also flattening nested tuple while lowering to LLVM
dialect types. There does not seem to be a deep reason for doing that
and doing it causes issues in fir.coordinate_of generated on such tuple
(a fir.coordinate_of getting tuple<B, C> in tuple<A, tuple<B, C>>
ended-up lowered to an LLVM GEP getting B).

[clementval]

LGTM

[schweitz]

Allow fir.box type to be a member of a tuple<> or fir.type<>, in which case it should be ensured it should be ensured the fir.box member is not translate to the struct type of a Fortran runtime descriptor, and not a pointer to it.

I don't understand this sentence.

[jeanPerier]

In D118701#3287841, @schweitz wrote:

Allow fir.box type to be a member of a tuple<> or fir.type<>, in which case it should be ensured it should be ensured the fir.box member is not translate to the struct type of a Fortran runtime descriptor, and not a pointer to it.

I don't understand this sentence.

I have rephrased it in the actual commit message.

flang/lib/Optimizer/CodeGen/TypeConverter.h

addConversion([&](fir::TypeDescType tdesc) {
       return convertTypeDescType(tdesc.getContext());
     });
     addConversion([&](fir::VectorType vecTy) {
       return mlir::VectorType::get(llvm::ArrayRef<int64_t>(vecTy.getLen()),
                                    convertType(vecTy.getEleTy()));
     });
     addConversion([&](mlir::TupleType tuple) {
       LLVM_DEBUG(llvm::dbgs() << "type convert: " << tuple << '\n');
-      llvm::SmallVector<mlir::Type> inMembers;
-      tuple.getFlattenedTypes(inMembers);
       llvm::SmallVector<mlir::Type> members;
-      for (auto mem : inMembers)
+      for (auto mem : tuple.getTypes()) {
+        // Prevent fir.box from degenerating to a pointer to a descriptor in the
+        // context of a tuple type.
+        if (auto box = mem.dyn_cast<fir::BoxType>())
+          members.push_back(convertBoxTypeAsStruct(box));
+        else
           members.push_back(convertType(mem).cast<mlir::Type>());
+      }
       return mlir::LLVM::LLVMStructType::getLiteral(&getContext(), members,
                                                     /*isPacked=*/false);
     });
   }
 
   // i32 is used here because LLVM wants i32 constants when indexing into struct
   // types. Indexing into other aggregate types is more flexible.
   mlir::Type offsetType() { return mlir::IntegerType::get(&getContext(), 32); }
 
   // i64 can be used to index into aggregates like arrays
   mlir::Type indexType() { return mlir::IntegerType::get(&getContext(), 64); }
 
   // fir.type<name(p : TY'...){f : TY...}>  -->  llvm<"%name = { ty... }">
   llvm::Optional<LogicalResult>
   convertRecordType(fir::RecordType derived, SmallVectorImpl<Type> &results,
                     ArrayRef<Type> callStack) {
     auto name = derived.getName();
     auto st = mlir::LLVM::LLVMStructType::getIdentified(&getContext(), name);
     if (llvm::count(callStack, derived) > 1) {
       results.push_back(st);
       return success();
     }
     llvm::SmallVector<mlir::Type> members;
     for (auto mem : derived.getTypeList()) {
+      // Prevent fir.box from degenerating to a pointer to a descriptor in the
+      // context of a record type.
+      if (auto box = mem.second.dyn_cast<fir::BoxType>())
+        members.push_back(convertBoxTypeAsStruct(box));
+      else
         members.push_back(convertType(mem.second).cast<mlir::Type>());
     }
     if (mlir::failed(st.setBody(members, /*isPacked=*/false)))
       return failure();
     results.push_back(st);
     return success();
   }
 
   // Is an extended descriptor needed given the element type of a fir.box type ?
if (requiresExtendedDesc(ele)) {
               mlir::LLVM::LLVMArrayType::get(rowTy, numLenParams));
         }
     }
     return mlir::LLVM::LLVMPointerType::get(
         mlir::LLVM::LLVMStructType::getLiteral(&getContext(), dataDescFields,
                                                /*isPacked=*/false));
   }
 
+  /// Convert fir.box type to the corresponding llvm struct type instead of a
+  /// pointer to this struct type.
+  mlir::Type convertBoxTypeAsStruct(BoxType box) {
+    return convertBoxType(box)
+        .cast<mlir::LLVM::LLVMPointerType>()
+        .getElementType();
+  }
+
   unsigned characterBitsize(fir::CharacterType charTy) {
     return kindMapping.getCharacterBitsize(charTy.getFKind());
   }
 
   // fir.char<k,?>  -->  llvm<"ix">          where ix is scaled by kind mapping
   // fir.char<k,n>  -->  llvm.array<n x "ix">
   mlir::Type convertCharType(fir::CharacterType charTy) {
     auto iTy = mlir::IntegerType::get(&getContext(), characterBitsize(charTy));

flang/lib/Optimizer/Dialect/FIRType.cpp

 
 /// Is `ty` a standard or FIR integer type?
 static bool isaIntegerType(mlir::Type ty) {
   // TODO: why aren't we using isa_integer? investigatation required.
   return ty.isa<mlir::IntegerType>() || ty.isa<fir::IntegerType>();
 }
 
 bool verifyRecordMemberType(mlir::Type ty) {
-  return !(ty.isa<BoxType>() || ty.isa<BoxCharType>() ||
-           ty.isa<BoxProcType>() || ty.isa<ShapeType>() ||
-           ty.isa<ShapeShiftType>() || ty.isa<ShiftType>() ||
-           ty.isa<SliceType>() || ty.isa<FieldType>() || ty.isa<LenType>() ||
-           ty.isa<ReferenceType>() || ty.isa<TypeDescType>());
+  return !(ty.isa<BoxCharType>() || ty.isa<BoxProcType>() ||
+           ty.isa<ShapeType>() || ty.isa<ShapeShiftType>() ||
+           ty.isa<ShiftType>() || ty.isa<SliceType>() || ty.isa<FieldType>() ||
+           ty.isa<LenType>() || ty.isa<ReferenceType>() ||
+           ty.isa<TypeDescType>());
 }
 
 bool verifySameLists(llvm::ArrayRef<RecordType::TypePair> a1,
                      llvm::ArrayRef<RecordType::TypePair> a2) {
   // FIXME: do we need to allow for any variance here?
   return a1 == a2;
 }
 

flang/test/Fir/types-to-llvm.fir

 
 func private @foo2(%arg : !fir.tdesc<f32>)
 // CHECK-LABEL: foo2
 // CHECK-SAME:  !llvm.ptr<i8>
 
 func private @foo3(%arg : !fir.tdesc<!fir.type<derived7{f1:f32,f2:f32}>>)
 // CHECK-LABEL: foo3
 // CHECK-SAME:  !llvm.ptr<i8>
+
+// -----
+
+// Test nested tuple types
+func private @foo0(%arg0: tuple<i64, tuple<f32, i64>>)
+// CHECK-LABEL: foo0
+// CHECK-SAME: !llvm.struct<(i64, struct<(f32, i64)>)>
+
+// -----
+
+// Test that fir.box inside tuple and derived type are lowered to struct type.
+func private @foo0(%arg0: tuple<i64, !fir.box<i32>>)
+// CHECK-LABEL: foo0
+// CHECK-SAME: !llvm.struct<(i64, struct<(ptr<i32>, i{{.*}})>)>
+
+func private @foo1(%arg0: !fir.type<derived8{a:i64,b:!fir.box<i32>}>)
+// CHECK-LABEL: foo1
+// CHECK-SAME: !llvm.struct<"derived8", (i64, struct<(ptr<i32>, i{{.*}})>)>