[flang-commits] [flang] [flang][OpenMP] Convert repeatable clauses (except Map) in ClauseProc… (PR #81623)

Krzysztof Parzyszek via flang-commits flang-commits at lists.llvm.org
Thu Mar 14 16:23:06 PDT 2024


https://github.com/kparzysz updated https://github.com/llvm/llvm-project/pull/81623

>From e16585a087766f6c8f0fba4ea78de03756b4ec15 Mon Sep 17 00:00:00 2001
From: Krzysztof Parzyszek <Krzysztof.Parzyszek at amd.com>
Date: Wed, 21 Feb 2024 12:51:13 -0600
Subject: [PATCH 1/3] [flang][OpenMP] Implement flexible OpenMP clause
 representation

Introduce a set of generic classes (templates) that represent OpenMP
clauses in a language-agnostic manner. OpenMP clauses can contain
expressions and data objects and the exact representation of each
depends on the source language of the compiled program. To deal with
this, the templates depend on two type parameters:
- IdType: type that represent object's identity (in a way that
  satisfied OpenMP requirements), and
- ExprType: type that can represent numeric values, as well as
  data references (e.g. x.y[1].z[2]).

In addition to that, implement code instantiating these templates
from flang's AST.

This patch only introduces the new classes, they are not yet used
anywhere.
---
 flang/lib/Lower/CMakeLists.txt     |   1 +
 flang/lib/Lower/OpenMP/ClauseT.h   | 715 ++++++++++++++++++++++++++++
 flang/lib/Lower/OpenMP/Clauses.cpp | 727 +++++++++++++++++++++++++++++
 flang/lib/Lower/OpenMP/Clauses.h   | 198 ++++++++
 4 files changed, 1641 insertions(+)
 create mode 100644 flang/lib/Lower/OpenMP/ClauseT.h
 create mode 100644 flang/lib/Lower/OpenMP/Clauses.cpp
 create mode 100644 flang/lib/Lower/OpenMP/Clauses.h

diff --git a/flang/lib/Lower/CMakeLists.txt b/flang/lib/Lower/CMakeLists.txt
index 5577a60f1daeac..f92d1a2bc7de18 100644
--- a/flang/lib/Lower/CMakeLists.txt
+++ b/flang/lib/Lower/CMakeLists.txt
@@ -25,6 +25,7 @@ add_flang_library(FortranLower
   Mangler.cpp
   OpenACC.cpp
   OpenMP/ClauseProcessor.cpp
+  OpenMP/Clauses.cpp
   OpenMP/DataSharingProcessor.cpp
   OpenMP/OpenMP.cpp
   OpenMP/ReductionProcessor.cpp
diff --git a/flang/lib/Lower/OpenMP/ClauseT.h b/flang/lib/Lower/OpenMP/ClauseT.h
new file mode 100644
index 00000000000000..b9fbbd18bf2b94
--- /dev/null
+++ b/flang/lib/Lower/OpenMP/ClauseT.h
@@ -0,0 +1,715 @@
+//===- ClauseT -- clause template definitions -----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+#ifndef FORTRAN_LOWER_OPENMP_CLAUSET_H
+#define FORTRAN_LOWER_OPENMP_CLAUSET_H
+
+#include "flang/Parser/parse-tree.h" // For enum reuse
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/raw_ostream.h"
+
+#include <algorithm>
+#include <iterator>
+#include <optional>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+#include <variant>
+#include <vector>
+
+#include "llvm/Frontend/OpenMP/OMP.h.inc"
+
+namespace tomp {
+
+template <typename T>
+using ListT = std::vector<T>;
+
+// A specialization of ObjectT<Id, Expr> must provide the following definitions:
+// {
+//    using IdType = Id;
+//    using ExprType = Expr;
+//
+//    auto id() const -> Id {
+//      return the identifier of the object (for use in tests for
+//         presence/absence of the object)
+//    }
+//
+//    auto ref() const -> const Expr& {
+//      return the expression accessing (referencing) the object
+//    }
+// }
+//
+// For example, the ObjectT instance created for "var[x+1]" would have
+// the `id()` return the identifier for `var`, and the `ref()` return the
+// representation of the array-access `var[x+1]`.
+template <typename Id, typename Expr>
+struct ObjectT;
+
+template <typename I, typename E>
+using ObjectListT = ListT<ObjectT<I, E>>;
+
+namespace clause {
+// Helper objects
+
+template <typename I, typename E>
+struct DefinedOperatorT {
+  struct DefinedOpName {
+    using WrapperTrait = std::true_type;
+    ObjectT<I, E> v;
+  };
+  using IntrinsicOperator = Fortran::parser::DefinedOperator::IntrinsicOperator;
+  using UnionTrait = std::true_type;
+  std::variant<DefinedOpName, IntrinsicOperator> u;
+};
+
+template <typename I, typename E>
+struct ProcedureDesignatorT {
+  using WrapperTrait = std::true_type;
+  ObjectT<I, E> v;
+};
+
+template <typename I, typename E>
+struct ReductionOperatorT {
+  using UnionTrait = std::true_type;
+  std::variant<DefinedOperatorT<I, E>, ProcedureDesignatorT<I, E>> u;
+};
+
+template <typename I, typename E>
+struct AcqRelT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct AcquireT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct AdjustArgsT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct AffinityT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct AlignT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct AppendArgsT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct AtT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct BindT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct CancellationConstructTypeT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct CaptureT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct CompareT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct DepobjT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct DestroyT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct DetachT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct DoacrossT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct DynamicAllocatorsT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct ExclusiveT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct FailT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct FlushT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct FullT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct InbranchT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct InclusiveT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct IndirectT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct InitT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct MatchT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct MemoryOrderT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct MergeableT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct MessageT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct NogroupT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct NotinbranchT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct NowaitT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct OmpxAttributeT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct OmpxBareT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct ReadT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct RelaxedT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct ReleaseT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct ReverseOffloadT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct SeqCstT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct SeverityT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct SimdT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct ThreadprivateT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct ThreadsT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct UnifiedAddressT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct UnifiedSharedMemoryT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct UnknownT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct UntiedT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct UpdateT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct UseT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct UsesAllocatorsT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct WeakT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct WhenT {
+  using EmptyTrait = std::true_type;
+};
+template <typename I, typename E>
+struct WriteT {
+  using EmptyTrait = std::true_type;
+};
+
+template <typename I, typename E>
+struct AlignedT {
+  using TupleTrait = std::true_type;
+  std::tuple<ObjectListT<I, E>, std::optional<E>> t;
+};
+
+template <typename I, typename E>
+struct AllocateT {
+  struct Modifier {
+    struct Allocator {
+      using WrapperTrait = std::true_type;
+      E v;
+    };
+    struct Align {
+      using WrapperTrait = std::true_type;
+      E v;
+    };
+    struct ComplexModifier {
+      using TupleTrait = std::true_type;
+      std::tuple<Allocator, Align> t;
+    };
+    using UnionTrait = std::true_type;
+    std::variant<Allocator, ComplexModifier, Align> u;
+  };
+  using TupleTrait = std::true_type;
+  std::tuple<std::optional<Modifier>, ObjectListT<I, E>> t;
+};
+
+template <typename I, typename E>
+struct AllocatorT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct AtomicDefaultMemOrderT {
+  using WrapperTrait = std::true_type;
+  using OmpAtomicDefaultMemOrderType =
+      Fortran::common::OmpAtomicDefaultMemOrderType;
+  OmpAtomicDefaultMemOrderType v;
+};
+
+template <typename I, typename E>
+struct CollapseT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct CopyinT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct CopyprivateT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct DefaultmapT {
+  using ImplicitBehavior =
+      Fortran::parser::OmpDefaultmapClause::ImplicitBehavior;
+  using VariableCategory =
+      Fortran::parser::OmpDefaultmapClause::VariableCategory;
+  using TupleTrait = std::true_type;
+  std::tuple<ImplicitBehavior, std::optional<VariableCategory>> t;
+};
+
+template <typename I, typename E>
+struct DefaultT {
+  using Type = Fortran::parser::OmpDefaultClause::Type;
+  using WrapperTrait = std::true_type;
+  Type v;
+};
+
+template <typename I, typename E>
+struct DependT {
+  struct Source {
+    using EmptyTrait = std::true_type;
+  };
+  struct Sink {
+    using Length = std::tuple<DefinedOperatorT<I, E>, E>;
+    using Vec = std::tuple<ObjectT<I, E>, std::optional<Length>>;
+    using WrapperTrait = std::true_type;
+    ListT<Vec> v;
+  };
+  using Type = Fortran::parser::OmpDependenceType::Type;
+  struct InOut {
+    using TupleTrait = std::true_type;
+    std::tuple<Type, ObjectListT<I, E>> t;
+  };
+  using UnionTrait = std::true_type;
+  std::variant<Source, Sink, InOut> u;
+};
+
+template <typename I, typename E>
+struct DeviceT {
+  using DeviceModifier = Fortran::parser::OmpDeviceClause::DeviceModifier;
+  using TupleTrait = std::true_type;
+  std::tuple<std::optional<DeviceModifier>, E> t;
+};
+
+template <typename I, typename E>
+struct DeviceTypeT {
+  using Type = Fortran::parser::OmpDeviceTypeClause::Type;
+  using WrapperTrait = std::true_type;
+  Type v;
+};
+
+template <typename I, typename E>
+struct DistScheduleT {
+  using WrapperTrait = std::true_type;
+  std::optional<E> v;
+};
+
+template <typename I, typename E>
+struct EnterT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct FilterT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct FinalT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct FirstprivateT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct FromT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct GrainsizeT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct HasDeviceAddrT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct HintT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct IfT {
+  using DirectiveNameModifier =
+      Fortran::parser::OmpIfClause::DirectiveNameModifier;
+  using TupleTrait = std::true_type;
+  std::tuple<std::optional<DirectiveNameModifier>, E> t;
+};
+
+template <typename I, typename E>
+struct InReductionT {
+  using TupleTrait = std::true_type;
+  std::tuple<ReductionOperatorT<I, E>, ObjectListT<I, E>> t;
+};
+
+template <typename I, typename E>
+struct IsDevicePtrT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct LastprivateT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct LinearT {
+  struct Modifier {
+    using Type = Fortran::parser::OmpLinearModifier::Type;
+    using WrapperTrait = std::true_type;
+    Type v;
+  };
+  using TupleTrait = std::true_type;
+  std::tuple<std::optional<Modifier>, ObjectListT<I, E>, std::optional<E>> t;
+};
+
+template <typename I, typename E>
+struct LinkT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct MapT {
+  struct MapType {
+    struct Always {
+      using EmptyTrait = std::true_type;
+    };
+    using Type = Fortran::parser::OmpMapType::Type;
+    using TupleTrait = std::true_type;
+    std::tuple<std::optional<Always>, Type> t;
+  };
+  using TupleTrait = std::true_type;
+  std::tuple<std::optional<MapType>, ObjectListT<I, E>> t;
+};
+
+template <typename I, typename E>
+struct NocontextT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct NontemporalT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct NovariantsT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct NumTasksT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct NumTeamsT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct NumThreadsT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct OmpxDynCgroupMemT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct OrderedT {
+  using WrapperTrait = std::true_type;
+  std::optional<E> v;
+};
+
+template <typename I, typename E>
+struct OrderT {
+  using Kind = Fortran::parser::OmpOrderModifier::Kind;
+  using Type = Fortran::parser::OmpOrderClause::Type;
+  using TupleTrait = std::true_type;
+  std::tuple<std::optional<Kind>, Type> t;
+};
+
+template <typename I, typename E>
+struct PartialT {
+  using WrapperTrait = std::true_type;
+  std::optional<E> v;
+};
+
+template <typename I, typename E>
+struct PriorityT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct PrivateT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct ProcBindT {
+  using Type = Fortran::parser::OmpProcBindClause::Type;
+  using WrapperTrait = std::true_type;
+  Type v;
+};
+
+template <typename I, typename E>
+struct ReductionT {
+  using TupleTrait = std::true_type;
+  std::tuple<ReductionOperatorT<I, E>, ObjectListT<I, E>> t;
+};
+
+template <typename I, typename E>
+struct SafelenT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct ScheduleT {
+  using ModType = Fortran::parser::OmpScheduleModifierType::ModType;
+  struct ScheduleModifier {
+    using TupleTrait = std::true_type;
+    std::tuple<ModType, std::optional<ModType>> t;
+  };
+  using ScheduleType = Fortran::parser::OmpScheduleClause::ScheduleType;
+  using TupleTrait = std::true_type;
+  std::tuple<std::optional<ScheduleModifier>, ScheduleType, std::optional<E>> t;
+};
+
+template <typename I, typename E>
+struct SharedT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct SimdlenT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct SizesT {
+  using WrapperTrait = std::true_type;
+  ListT<E> v;
+};
+
+template <typename I, typename E>
+struct TaskReductionT {
+  using TupleTrait = std::true_type;
+  std::tuple<ReductionOperatorT<I, E>, ObjectListT<I, E>> t;
+};
+
+template <typename I, typename E>
+struct ThreadLimitT {
+  using WrapperTrait = std::true_type;
+  E v;
+};
+
+template <typename I, typename E>
+struct ToT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct UniformT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct UseDeviceAddrT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+struct UseDevicePtrT {
+  using WrapperTrait = std::true_type;
+  ObjectListT<I, E> v;
+};
+
+template <typename I, typename E>
+using UnionOfAllClausesT = std::variant<
+    AcqRelT<I, E>, AcquireT<I, E>, AdjustArgsT<I, E>, AffinityT<I, E>,
+    AlignT<I, E>, AlignedT<I, E>, AllocateT<I, E>, AllocatorT<I, E>,
+    AppendArgsT<I, E>, AtT<I, E>, AtomicDefaultMemOrderT<I, E>, BindT<I, E>,
+    CancellationConstructTypeT<I, E>, CaptureT<I, E>, CollapseT<I, E>,
+    CompareT<I, E>, CopyprivateT<I, E>, CopyinT<I, E>, DefaultT<I, E>,
+    DefaultmapT<I, E>, DependT<I, E>, DepobjT<I, E>, DestroyT<I, E>,
+    DetachT<I, E>, DeviceT<I, E>, DeviceTypeT<I, E>, DistScheduleT<I, E>,
+    DoacrossT<I, E>, DynamicAllocatorsT<I, E>, EnterT<I, E>, ExclusiveT<I, E>,
+    FailT<I, E>, FilterT<I, E>, FinalT<I, E>, FirstprivateT<I, E>, FlushT<I, E>,
+    FromT<I, E>, FullT<I, E>, GrainsizeT<I, E>, HasDeviceAddrT<I, E>,
+    HintT<I, E>, IfT<I, E>, InReductionT<I, E>, InbranchT<I, E>,
+    InclusiveT<I, E>, IndirectT<I, E>, InitT<I, E>, IsDevicePtrT<I, E>,
+    LastprivateT<I, E>, LinearT<I, E>, LinkT<I, E>, MapT<I, E>, MatchT<I, E>,
+    MemoryOrderT<I, E>, MergeableT<I, E>, MessageT<I, E>, NogroupT<I, E>,
+    NowaitT<I, E>, NocontextT<I, E>, NontemporalT<I, E>, NotinbranchT<I, E>,
+    NovariantsT<I, E>, NumTasksT<I, E>, NumTeamsT<I, E>, NumThreadsT<I, E>,
+    OmpxAttributeT<I, E>, OmpxDynCgroupMemT<I, E>, OmpxBareT<I, E>,
+    OrderT<I, E>, OrderedT<I, E>, PartialT<I, E>, PriorityT<I, E>,
+    PrivateT<I, E>, ProcBindT<I, E>, ReadT<I, E>, ReductionT<I, E>,
+    RelaxedT<I, E>, ReleaseT<I, E>, ReverseOffloadT<I, E>, SafelenT<I, E>,
+    ScheduleT<I, E>, SeqCstT<I, E>, SeverityT<I, E>, SharedT<I, E>, SimdT<I, E>,
+    SimdlenT<I, E>, SizesT<I, E>, TaskReductionT<I, E>, ThreadLimitT<I, E>,
+    ThreadprivateT<I, E>, ThreadsT<I, E>, ToT<I, E>, UnifiedAddressT<I, E>,
+    UnifiedSharedMemoryT<I, E>, UniformT<I, E>, UnknownT<I, E>, UntiedT<I, E>,
+    UpdateT<I, E>, UseT<I, E>, UseDeviceAddrT<I, E>, UseDevicePtrT<I, E>,
+    UsesAllocatorsT<I, E>, WeakT<I, E>, WhenT<I, E>, WriteT<I, E>>;
+} // namespace clause
+
+template <typename Id, typename Expr>
+struct ClauseT {
+  llvm::omp::Clause id; // The numeric id of the clause
+  using UnionTrait = std::true_type;
+  clause::UnionOfAllClausesT<Id, Expr> u;
+};
+
+} // namespace tomp
+
+#endif // FORTRAN_LOWER_OPENMP_CLAUSET_H
diff --git a/flang/lib/Lower/OpenMP/Clauses.cpp b/flang/lib/Lower/OpenMP/Clauses.cpp
new file mode 100644
index 00000000000000..dd7ce71f6ddca4
--- /dev/null
+++ b/flang/lib/Lower/OpenMP/Clauses.cpp
@@ -0,0 +1,727 @@
+//===-- Clauses.cpp -- OpenMP clause handling -----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Clauses.h"
+
+#include "flang/Common/idioms.h"
+#include "flang/Evaluate/expression.h"
+#include "flang/Parser/parse-tree.h"
+#include "flang/Semantics/expression.h"
+#include "flang/Semantics/symbol.h"
+
+#include "llvm/Frontend/OpenMP/OMPConstants.h"
+
+#include <list>
+#include <optional>
+#include <tuple>
+#include <utility>
+#include <variant>
+
+namespace detail {
+template <typename C>
+llvm::omp::Clause getClauseIdForClass(C &&) {
+  using namespace Fortran;
+  using A = llvm::remove_cvref_t<C>; // A is referenced in OMP.inc
+  // The code included below contains a sequence of checks like the following
+  // for each OpenMP clause
+  //   if constexpr (std::is_same_v<A, parser::OmpClause::AcqRel>)
+  //     return llvm::omp::Clause::OMPC_acq_rel;
+  //   [...]
+#define GEN_FLANG_CLAUSE_PARSER_KIND_MAP
+#include "llvm/Frontend/OpenMP/OMP.inc"
+}
+} // namespace detail
+
+static llvm::omp::Clause getClauseId(const Fortran::parser::OmpClause &clause) {
+  return std::visit([](auto &&s) { return detail::getClauseIdForClass(s); },
+                    clause.u);
+}
+
+namespace omp {
+using SymbolWithDesignator = std::tuple<semantics::Symbol *, MaybeExpr>;
+
+struct SymDsgExtractor {
+  template <typename T>
+  static T &&AsRvalueRef(T &&t) {
+    return std::move(t);
+  }
+  template <typename T>
+  static T AsRvalueRef(const T &t) {
+    return t;
+  }
+
+  static semantics::Symbol *symbol_addr(const evaluate::SymbolRef &ref) {
+    // Symbols cannot be created after semantic checks, so all symbol
+    // pointers that are non-null must point to one of those pre-existing
+    // objects. Throughout the code, symbols are often pointed to by
+    // non-const pointers, so there is no harm in casting the constness
+    // away.
+    return const_cast<semantics::Symbol *>(&ref.get());
+  }
+
+  template <typename T>
+  static SymbolWithDesignator visit(T &&) {
+    // Use this to see missing overloads:
+    // llvm::errs() << "NULL: " << __PRETTY_FUNCTION__ << '\n';
+    return SymbolWithDesignator{};
+  }
+
+  template <typename T>
+  static SymbolWithDesignator visit(const evaluate::Designator<T> &e) {
+    return std::make_tuple(symbol_addr(*e.GetLastSymbol()),
+                           evaluate::AsGenericExpr(AsRvalueRef(e)));
+  }
+
+  static SymbolWithDesignator visit(const evaluate::ProcedureDesignator &e) {
+    return std::make_tuple(symbol_addr(*e.GetSymbol()), std::nullopt);
+  }
+
+  template <typename T>
+  static SymbolWithDesignator visit(const evaluate::Expr<T> &e) {
+    return std::visit([](auto &&s) { return visit(s); }, e.u);
+  }
+
+  static void verify(const SymbolWithDesignator &sd) {
+    const semantics::Symbol *symbol = std::get<0>(sd);
+    assert(symbol && "Expecting symbol");
+    auto &maybeDsg = std::get<1>(sd);
+    if (!maybeDsg)
+      return; // Symbol with no designator -> OK
+    std::optional<evaluate::DataRef> maybeRef =
+        evaluate::ExtractDataRef(*maybeDsg);
+    if (maybeRef) {
+      if (&maybeRef->GetLastSymbol() == symbol)
+        return; // Symbol with a designator for it -> OK
+      llvm_unreachable("Expecting designator for given symbol");
+    } else {
+      // This could still be a Substring or ComplexPart, but at least Substring
+      // is not allowed in OpenMP.
+      maybeDsg->dump();
+      llvm_unreachable("Expecting DataRef designator");
+    }
+  }
+};
+
+SymbolWithDesignator getSymbolAndDesignator(const MaybeExpr &expr) {
+  if (!expr)
+    return SymbolWithDesignator{};
+  return std::visit([](auto &&s) { return SymDsgExtractor::visit(s); },
+                    expr->u);
+}
+
+Object makeObject(const parser::Name &name,
+                  semantics::SemanticsContext &semaCtx) {
+  assert(name.symbol && "Expecting Symbol");
+  return Object{name.symbol, std::nullopt};
+}
+
+Object makeObject(const parser::Designator &dsg,
+                  semantics::SemanticsContext &semaCtx) {
+  evaluate::ExpressionAnalyzer ea{semaCtx};
+  SymbolWithDesignator sd = getSymbolAndDesignator(ea.Analyze(dsg));
+  SymDsgExtractor::verify(sd);
+  return Object{std::get<0>(sd), std::move(std::get<1>(sd))};
+}
+
+Object makeObject(const parser::StructureComponent &comp,
+                  semantics::SemanticsContext &semaCtx) {
+  evaluate::ExpressionAnalyzer ea{semaCtx};
+  SymbolWithDesignator sd = getSymbolAndDesignator(ea.Analyze(comp));
+  SymDsgExtractor::verify(sd);
+  return Object{std::get<0>(sd), std::move(std::get<1>(sd))};
+}
+
+Object makeObject(const parser::OmpObject &object,
+                  semantics::SemanticsContext &semaCtx) {
+  // If object is a common block, expression analyzer won't be able to
+  // do anything.
+  if (const auto *name = std::get_if<parser::Name>(&object.u)) {
+    assert(name->symbol && "Expecting Symbol");
+    return Object{name->symbol, std::nullopt};
+  }
+  // OmpObject is std::variant<Designator, /*common block*/ Name>;
+  return makeObject(std::get<parser::Designator>(object.u), semaCtx);
+}
+
+std::optional<Object>
+getBaseObject(const Object &object,
+              Fortran::semantics::SemanticsContext &semaCtx) {
+  // If it's just the symbol, then there is no base.
+  if (!object.id())
+    return std::nullopt;
+
+  auto maybeRef = evaluate::ExtractDataRef(*object.ref());
+  if (!maybeRef)
+    return std::nullopt;
+
+  evaluate::DataRef ref = *maybeRef;
+
+  if (std::get_if<evaluate::SymbolRef>(&ref.u)) {
+    return std::nullopt;
+  } else if (auto *comp = std::get_if<evaluate::Component>(&ref.u)) {
+    const evaluate::DataRef &base = comp->base();
+    return Object{SymDsgExtractor::symbol_addr(base.GetLastSymbol()),
+                  evaluate::AsGenericExpr(SymDsgExtractor::AsRvalueRef(base))};
+  } else if (auto *arr = std::get_if<evaluate::ArrayRef>(&ref.u)) {
+    const evaluate::NamedEntity &base = arr->base();
+    evaluate::ExpressionAnalyzer ea{semaCtx};
+    if (auto *comp = base.UnwrapComponent()) {
+      return Object{
+          SymDsgExtractor::symbol_addr(comp->symbol()),
+          ea.Designate(evaluate::DataRef{SymDsgExtractor::AsRvalueRef(*comp)})};
+    } else if (base.UnwrapSymbolRef()) {
+      return std::nullopt;
+    }
+  } else {
+    assert(std::holds_alternative<evaluate::CoarrayRef>(ref.u));
+    llvm_unreachable("Coarray reference not supported at the moment");
+  }
+  return std::nullopt;
+}
+
+namespace clause {
+// Helper objects
+#ifdef EMPTY_CLASS
+#undef EMPTY_CLASS
+#endif
+#define EMPTY_CLASS(cls)                                                       \
+  cls make(const parser::OmpClause::cls &, semantics::SemanticsContext &) {    \
+    return cls{};                                                              \
+  }                                                                            \
+  [[maybe_unused]] extern int xyzzy_semicolon_absorber
+
+#ifdef WRAPPER_CLASS
+#undef WRAPPER_CLASS
+#endif
+#define WRAPPER_CLASS(cls, content)                                            \
+  [[maybe_unused]] extern int xyzzy_semicolon_absorber
+#define GEN_FLANG_CLAUSE_PARSER_CLASSES
+#include "llvm/Frontend/OpenMP/OMP.inc"
+#undef EMPTY_CLASS
+#undef WRAPPER_CLASS
+
+using DefinedOperator = tomp::clause::DefinedOperatorT<SymIdent, SymReference>;
+using ProcedureDesignator =
+    tomp::clause::ProcedureDesignatorT<SymIdent, SymReference>;
+using ReductionOperator =
+    tomp::clause::ReductionOperatorT<SymIdent, SymReference>;
+
+DefinedOperator makeDefOp(const parser::DefinedOperator &inp,
+                          semantics::SemanticsContext &semaCtx) {
+  return DefinedOperator{
+      std::visit(common::visitors{
+                     [&](const parser::DefinedOpName &s) {
+                       return DefinedOperator{DefinedOperator::DefinedOpName{
+                           makeObject(s.v, semaCtx)}};
+                     },
+                     [&](const parser::DefinedOperator::IntrinsicOperator &s) {
+                       return DefinedOperator{s};
+                     },
+                 },
+                 inp.u),
+  };
+}
+
+ProcedureDesignator makeProcDsg(const parser::ProcedureDesignator &inp,
+                                semantics::SemanticsContext &semaCtx) {
+  return ProcedureDesignator{std::visit(
+      common::visitors{
+          [&](const parser::Name &t) { return makeObject(t, semaCtx); },
+          [&](const parser::ProcComponentRef &t) {
+            return makeObject(t.v.thing, semaCtx);
+          },
+      },
+      inp.u)};
+}
+
+ReductionOperator makeRedOp(const parser::OmpReductionOperator &inp,
+                            semantics::SemanticsContext &semaCtx) {
+  return std::visit(common::visitors{
+                        [&](const parser::DefinedOperator &s) {
+                          return ReductionOperator{makeDefOp(s, semaCtx)};
+                        },
+                        [&](const parser::ProcedureDesignator &s) {
+                          return ReductionOperator{makeProcDsg(s, semaCtx)};
+                        },
+                    },
+                    inp.u);
+}
+
+// Actual clauses. Each T (where OmpClause::T exists) has its "make".
+Aligned make(const parser::OmpClause::Aligned &inp,
+             semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpAlignedClause
+  auto &t0 = std::get<parser::OmpObjectList>(inp.v.t);
+  auto &t1 = std::get<std::optional<parser::ScalarIntConstantExpr>>(inp.v.t);
+
+  return Aligned{{
+      makeList(t0, semaCtx),
+      maybeApply(makeExprF(semaCtx), t1),
+  }};
+}
+
+Allocate make(const parser::OmpClause::Allocate &inp,
+              semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpAllocateClause
+  using wrapped = parser::OmpAllocateClause;
+  auto &t0 = std::get<std::optional<wrapped::AllocateModifier>>(inp.v.t);
+  auto &t1 = std::get<parser::OmpObjectList>(inp.v.t);
+
+  auto convert = [&](auto &&s) -> Allocate::Modifier {
+    using Modifier = Allocate::Modifier;
+    using Allocator = Modifier::Allocator;
+    using Align = Modifier::Align;
+    using ComplexModifier = Modifier::ComplexModifier;
+
+    return Modifier{
+        std::visit(
+            common::visitors{
+                [&](const wrapped::AllocateModifier::Allocator &v) {
+                  return Modifier{Allocator{makeExpr(v.v, semaCtx)}};
+                },
+                [&](const wrapped::AllocateModifier::ComplexModifier &v) {
+                  auto &s0 =
+                      std::get<wrapped::AllocateModifier::Allocator>(v.t);
+                  auto &s1 = std::get<wrapped::AllocateModifier::Align>(v.t);
+                  return Modifier{ComplexModifier{{
+                      Allocator{makeExpr(s0.v, semaCtx)},
+                      Align{makeExpr(s1.v, semaCtx)},
+                  }}};
+                },
+                [&](const wrapped::AllocateModifier::Align &v) {
+                  return Modifier{Align{makeExpr(v.v, semaCtx)}};
+                },
+            },
+            s.u),
+    };
+  };
+
+  return Allocate{{maybeApply(convert, t0), makeList(t1, semaCtx)}};
+}
+
+Allocator make(const parser::OmpClause::Allocator &inp,
+               semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarIntExpr
+  return Allocator{makeExpr(inp.v, semaCtx)};
+}
+
+AtomicDefaultMemOrder make(const parser::OmpClause::AtomicDefaultMemOrder &inp,
+                           semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpAtomicDefaultMemOrderClause
+  return AtomicDefaultMemOrder{inp.v.v};
+}
+
+Collapse make(const parser::OmpClause::Collapse &inp,
+              semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarIntConstantExpr
+  return Collapse{makeExpr(inp.v, semaCtx)};
+}
+
+Copyin make(const parser::OmpClause::Copyin &inp,
+            semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return Copyin{makeList(inp.v, semaCtx)};
+}
+
+Copyprivate make(const parser::OmpClause::Copyprivate &inp,
+                 semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return Copyprivate{makeList(inp.v, semaCtx)};
+}
+
+Defaultmap make(const parser::OmpClause::Defaultmap &inp,
+                semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpDefaultmapClause
+  using wrapped = parser::OmpDefaultmapClause;
+
+  auto &t0 = std::get<wrapped::ImplicitBehavior>(inp.v.t);
+  auto &t1 = std::get<std::optional<wrapped::VariableCategory>>(inp.v.t);
+  return Defaultmap{{t0, t1}};
+}
+
+Default make(const parser::OmpClause::Default &inp,
+             semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpDefaultClause
+  return Default{inp.v.v};
+}
+
+Depend make(const parser::OmpClause::Depend &inp,
+            semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpDependClause
+  using wrapped = parser::OmpDependClause;
+
+  return std::visit(
+      common::visitors{
+          [&](const wrapped::Source &s) { return Depend{Depend::Source{}}; },
+          [&](const wrapped::Sink &s) {
+            auto convert = [&](const parser::OmpDependSinkVec &v) {
+              auto &t0 = std::get<parser::Name>(v.t);
+              auto &t1 =
+                  std::get<std::optional<parser::OmpDependSinkVecLength>>(v.t);
+              auto convert1 = [&](const parser::OmpDependSinkVecLength &u) {
+                auto &s0 = std::get<parser::DefinedOperator>(u.t);
+                auto &s1 = std::get<parser::ScalarIntConstantExpr>(u.t);
+                return Depend::Sink::Length{makeDefOp(s0, semaCtx),
+                                            makeExpr(s1, semaCtx)};
+              };
+              return Depend::Sink::Vec{makeObject(t0, semaCtx),
+                                       maybeApply(convert1, t1)};
+            };
+            return Depend{Depend::Sink{makeList(s.v, convert)}};
+          },
+          [&](const wrapped::InOut &s) {
+            auto &t0 = std::get<parser::OmpDependenceType>(s.t);
+            auto &t1 = std::get<std::list<parser::Designator>>(s.t);
+            auto convert = [&](const parser::Designator &t) {
+              return makeObject(t, semaCtx);
+            };
+            return Depend{Depend::InOut{{t0.v, makeList(t1, convert)}}};
+          },
+      },
+      inp.v.u);
+}
+
+Device make(const parser::OmpClause::Device &inp,
+            semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpDeviceClause
+  using wrapped = parser::OmpDeviceClause;
+
+  auto &t0 = std::get<std::optional<wrapped::DeviceModifier>>(inp.v.t);
+  auto &t1 = std::get<parser::ScalarIntExpr>(inp.v.t);
+  return Device{{t0, makeExpr(t1, semaCtx)}};
+}
+
+DeviceType make(const parser::OmpClause::DeviceType &inp,
+                semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpDeviceTypeClause
+  return DeviceType{inp.v.v};
+}
+
+DistSchedule make(const parser::OmpClause::DistSchedule &inp,
+                  semantics::SemanticsContext &semaCtx) {
+  // inp.v -> std::optional<parser::ScalarIntExpr>
+  return DistSchedule{maybeApply(makeExprF(semaCtx), inp.v)};
+}
+
+Enter make(const parser::OmpClause::Enter &inp,
+           semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return Enter{makeList(inp.v, semaCtx)};
+}
+
+Filter make(const parser::OmpClause::Filter &inp,
+            semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarIntExpr
+  return Filter{makeExpr(inp.v, semaCtx)};
+}
+
+Final make(const parser::OmpClause::Final &inp,
+           semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarLogicalExpr
+  return Final{makeExpr(inp.v, semaCtx)};
+}
+
+Firstprivate make(const parser::OmpClause::Firstprivate &inp,
+                  semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return Firstprivate{makeList(inp.v, semaCtx)};
+}
+
+From make(const parser::OmpClause::From &inp,
+          semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return From{makeList(inp.v, semaCtx)};
+}
+
+Grainsize make(const parser::OmpClause::Grainsize &inp,
+               semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarIntExpr
+  return Grainsize{makeExpr(inp.v, semaCtx)};
+}
+
+HasDeviceAddr make(const parser::OmpClause::HasDeviceAddr &inp,
+                   semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return HasDeviceAddr{makeList(inp.v, semaCtx)};
+}
+
+Hint make(const parser::OmpClause::Hint &inp,
+          semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ConstantExpr
+  return Hint{makeExpr(inp.v, semaCtx)};
+}
+
+If make(const parser::OmpClause::If &inp,
+        semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpIfClause
+  using wrapped = parser::OmpIfClause;
+
+  auto &t0 = std::get<std::optional<wrapped::DirectiveNameModifier>>(inp.v.t);
+  auto &t1 = std::get<parser::ScalarLogicalExpr>(inp.v.t);
+  return If{{t0, makeExpr(t1, semaCtx)}};
+}
+
+InReduction make(const parser::OmpClause::InReduction &inp,
+                 semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpInReductionClause
+  auto &t0 = std::get<parser::OmpReductionOperator>(inp.v.t);
+  auto &t1 = std::get<parser::OmpObjectList>(inp.v.t);
+  return InReduction{{makeRedOp(t0, semaCtx), makeList(t1, semaCtx)}};
+}
+
+IsDevicePtr make(const parser::OmpClause::IsDevicePtr &inp,
+                 semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return IsDevicePtr{makeList(inp.v, semaCtx)};
+}
+
+Lastprivate make(const parser::OmpClause::Lastprivate &inp,
+                 semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return Lastprivate{makeList(inp.v, semaCtx)};
+}
+
+Linear make(const parser::OmpClause::Linear &inp,
+            semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpLinearClause
+  using wrapped = parser::OmpLinearClause;
+
+  return std::visit(
+      common::visitors{
+          [&](const wrapped::WithModifier &s) {
+            return Linear{{Linear::Modifier{s.modifier.v},
+                           makeList(s.names, makeObjectF(semaCtx)),
+                           maybeApply(makeExprF(semaCtx), s.step)}};
+          },
+          [&](const wrapped::WithoutModifier &s) {
+            return Linear{{std::nullopt,
+                           makeList(s.names, makeObjectF(semaCtx)),
+                           maybeApply(makeExprF(semaCtx), s.step)}};
+          },
+      },
+      inp.v.u);
+}
+
+Link make(const parser::OmpClause::Link &inp,
+          semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return Link{makeList(inp.v, semaCtx)};
+}
+
+Map make(const parser::OmpClause::Map &inp,
+         semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpMapClause
+  auto &t0 = std::get<std::optional<parser::OmpMapType>>(inp.v.t);
+  auto &t1 = std::get<parser::OmpObjectList>(inp.v.t);
+  auto convert = [](const parser::OmpMapType &s) {
+    auto &s0 = std::get<std::optional<parser::OmpMapType::Always>>(s.t);
+    auto &s1 = std::get<parser::OmpMapType::Type>(s.t);
+    auto convertT = [](parser::OmpMapType::Always) {
+      return Map::MapType::Always{};
+    };
+    return Map::MapType{{maybeApply(convertT, s0), s1}};
+  };
+  return Map{{maybeApply(convert, t0), makeList(t1, semaCtx)}};
+}
+
+Nocontext make(const parser::OmpClause::Nocontext &inp,
+               semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarLogicalExpr
+  return Nocontext{makeExpr(inp.v, semaCtx)};
+}
+
+Nontemporal make(const parser::OmpClause::Nontemporal &inp,
+                 semantics::SemanticsContext &semaCtx) {
+  // inp.v -> std::list<parser::Name>
+  return Nontemporal{makeList(inp.v, makeObjectF(semaCtx))};
+}
+
+Novariants make(const parser::OmpClause::Novariants &inp,
+                semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarLogicalExpr
+  return Novariants{makeExpr(inp.v, semaCtx)};
+}
+
+NumTasks make(const parser::OmpClause::NumTasks &inp,
+              semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarIntExpr
+  return NumTasks{makeExpr(inp.v, semaCtx)};
+}
+
+NumTeams make(const parser::OmpClause::NumTeams &inp,
+              semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarIntExpr
+  return NumTeams{makeExpr(inp.v, semaCtx)};
+}
+
+NumThreads make(const parser::OmpClause::NumThreads &inp,
+                semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarIntExpr
+  return NumThreads{makeExpr(inp.v, semaCtx)};
+}
+
+OmpxDynCgroupMem make(const parser::OmpClause::OmpxDynCgroupMem &inp,
+                      semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarIntExpr
+  return OmpxDynCgroupMem{makeExpr(inp.v, semaCtx)};
+}
+
+Ordered make(const parser::OmpClause::Ordered &inp,
+             semantics::SemanticsContext &semaCtx) {
+  // inp.v -> std::optional<parser::ScalarIntConstantExpr>
+  return Ordered{maybeApply(makeExprF(semaCtx), inp.v)};
+}
+
+Order make(const parser::OmpClause::Order &inp,
+           semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpOrderClause
+  using wrapped = parser::OmpOrderClause;
+  auto &t0 = std::get<std::optional<parser::OmpOrderModifier>>(inp.v.t);
+  auto &t1 = std::get<wrapped::Type>(inp.v.t);
+  auto convert = [](const parser::OmpOrderModifier &s) -> Order::Kind {
+    return std::get<parser::OmpOrderModifier::Kind>(s.u);
+  };
+  return Order{{maybeApply(convert, t0), t1}};
+}
+
+Partial make(const parser::OmpClause::Partial &inp,
+             semantics::SemanticsContext &semaCtx) {
+  // inp.v -> std::optional<parser::ScalarIntConstantExpr>
+  return Partial{maybeApply(makeExprF(semaCtx), inp.v)};
+}
+
+Priority make(const parser::OmpClause::Priority &inp,
+              semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarIntExpr
+  return Priority{makeExpr(inp.v, semaCtx)};
+}
+
+Private make(const parser::OmpClause::Private &inp,
+             semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return Private{makeList(inp.v, semaCtx)};
+}
+
+ProcBind make(const parser::OmpClause::ProcBind &inp,
+              semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpProcBindClause
+  return ProcBind{inp.v.v};
+}
+
+Reduction make(const parser::OmpClause::Reduction &inp,
+               semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpReductionClause
+  auto &t0 = std::get<parser::OmpReductionOperator>(inp.v.t);
+  auto &t1 = std::get<parser::OmpObjectList>(inp.v.t);
+  return Reduction{{makeRedOp(t0, semaCtx), makeList(t1, semaCtx)}};
+}
+
+Safelen make(const parser::OmpClause::Safelen &inp,
+             semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarIntConstantExpr
+  return Safelen{makeExpr(inp.v, semaCtx)};
+}
+
+Schedule make(const parser::OmpClause::Schedule &inp,
+              semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpScheduleClause
+  using wrapped = parser::OmpScheduleClause;
+
+  auto &t0 = std::get<std::optional<parser::OmpScheduleModifier>>(inp.v.t);
+  auto &t1 = std::get<wrapped::ScheduleType>(inp.v.t);
+  auto &t2 = std::get<std::optional<parser::ScalarIntExpr>>(inp.v.t);
+
+  auto convert = [](auto &&s) -> Schedule::ScheduleModifier {
+    auto &s0 = std::get<parser::OmpScheduleModifier::Modifier1>(s.t);
+    auto &s1 =
+        std::get<std::optional<parser::OmpScheduleModifier::Modifier2>>(s.t);
+
+    auto convert1 = [](auto &&v) { // Modifier1 or Modifier2
+      return v.v.v;
+    };
+    return Schedule::ScheduleModifier{{s0.v.v, maybeApply(convert1, s1)}};
+  };
+
+  return Schedule{
+      {maybeApply(convert, t0), t1, maybeApply(makeExprF(semaCtx), t2)}};
+}
+
+Shared make(const parser::OmpClause::Shared &inp,
+            semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return Shared{makeList(inp.v, semaCtx)};
+}
+
+Simdlen make(const parser::OmpClause::Simdlen &inp,
+             semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarIntConstantExpr
+  return Simdlen{makeExpr(inp.v, semaCtx)};
+}
+
+Sizes make(const parser::OmpClause::Sizes &inp,
+           semantics::SemanticsContext &semaCtx) {
+  // inp.v -> std::list<parser::ScalarIntExpr>
+  return Sizes{makeList(inp.v, makeExprF(semaCtx))};
+}
+
+TaskReduction make(const parser::OmpClause::TaskReduction &inp,
+                   semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpReductionClause
+  auto &t0 = std::get<parser::OmpReductionOperator>(inp.v.t);
+  auto &t1 = std::get<parser::OmpObjectList>(inp.v.t);
+  return TaskReduction{{makeRedOp(t0, semaCtx), makeList(t1, semaCtx)}};
+}
+
+ThreadLimit make(const parser::OmpClause::ThreadLimit &inp,
+                 semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::ScalarIntExpr
+  return ThreadLimit{makeExpr(inp.v, semaCtx)};
+}
+
+To make(const parser::OmpClause::To &inp,
+        semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return To{makeList(inp.v, semaCtx)};
+}
+
+Uniform make(const parser::OmpClause::Uniform &inp,
+             semantics::SemanticsContext &semaCtx) {
+  // inp.v -> std::list<parser::Name>
+  return Uniform{makeList(inp.v, makeObjectF(semaCtx))};
+}
+
+UseDeviceAddr make(const parser::OmpClause::UseDeviceAddr &inp,
+                   semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return UseDeviceAddr{makeList(inp.v, semaCtx)};
+}
+
+UseDevicePtr make(const parser::OmpClause::UseDevicePtr &inp,
+                  semantics::SemanticsContext &semaCtx) {
+  // inp.v -> parser::OmpObjectList
+  return UseDevicePtr{makeList(inp.v, semaCtx)};
+}
+} // namespace clause
+
+Clause makeClause(const Fortran::parser::OmpClause &cls,
+                  semantics::SemanticsContext &semaCtx) {
+  return std::visit(
+      [&](auto &&s) {
+        return makeClause(getClauseId(cls), clause::make(s, semaCtx),
+                          cls.source);
+      },
+      cls.u);
+}
+
+omp::List<Clause> makeList(const parser::OmpClauseList &clauses,
+                           semantics::SemanticsContext &semaCtx) {
+  return makeList(clauses.v, [&](const parser::OmpClause &s) {
+    return makeClause(s, semaCtx);
+  });
+}
+} // namespace omp
diff --git a/flang/lib/Lower/OpenMP/Clauses.h b/flang/lib/Lower/OpenMP/Clauses.h
new file mode 100644
index 00000000000000..e40663565ae603
--- /dev/null
+++ b/flang/lib/Lower/OpenMP/Clauses.h
@@ -0,0 +1,198 @@
+//===-- Clauses.h -- OpenMP clause handling -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+#ifndef FORTRAN_LOWER_OPENMP_CLAUSES_H
+#define FORTRAN_LOWER_OPENMP_CLAUSES_H
+
+#include "ClauseT.h"
+
+#include "flang/Evaluate/expression.h"
+#include "flang/Parser/parse-tree.h"
+#include "flang/Semantics/expression.h"
+#include "flang/Semantics/semantics.h"
+#include "flang/Semantics/symbol.h"
+
+#include "llvm/ADT/STLExtras.h"
+
+#include <optional>
+#include <type_traits>
+#include <utility>
+
+namespace omp {
+using namespace Fortran;
+using SomeType = evaluate::SomeType;
+using SomeExpr = semantics::SomeExpr;
+using MaybeExpr = semantics::MaybeExpr;
+
+using SymIdent = semantics::Symbol *;
+using SymReference = SomeExpr;
+
+template <typename T>
+using List = tomp::ListT<T>;
+} // namespace omp
+
+namespace tomp {
+template <>
+struct ObjectT<omp::SymIdent, omp::SymReference> {
+  using IdType = omp::SymIdent;
+  using ExprType = omp::SymReference;
+
+  const IdType &id() const { return symbol; }
+  const std::optional<ExprType> &ref() const { return designator; }
+
+  IdType symbol;
+  std::optional<ExprType> designator;
+};
+} // namespace tomp
+
+namespace omp {
+
+using Object = tomp::ObjectT<SymIdent, SymReference>;
+using ObjectList = tomp::ObjectListT<SymIdent, SymReference>;
+
+Object makeObject(const parser::OmpObject &object,
+                  semantics::SemanticsContext &semaCtx);
+Object makeObject(const parser::Name &name,
+                  semantics::SemanticsContext &semaCtx);
+Object makeObject(const parser::Designator &dsg,
+                  semantics::SemanticsContext &semaCtx);
+Object makeObject(const parser::StructureComponent &comp,
+                  semantics::SemanticsContext &semaCtx);
+
+inline auto makeObjectF(semantics::SemanticsContext &semaCtx) {
+  return [&](auto &&s) { return makeObject(s, semaCtx); };
+}
+
+template <typename T>
+SomeExpr makeExpr(T &&inp, semantics::SemanticsContext &semaCtx) {
+  auto maybeExpr = evaluate::ExpressionAnalyzer(semaCtx).Analyze(inp);
+  assert(maybeExpr);
+  return std::move(*maybeExpr);
+}
+
+inline auto makeExprF(semantics::SemanticsContext &semaCtx) {
+  return [&](auto &&s) { return makeExpr(s, semaCtx); };
+}
+
+template <
+    typename ContainerTy, typename FunctionTy,
+    typename ElemTy = typename llvm::remove_cvref_t<ContainerTy>::value_type,
+    typename ResultTy = std::invoke_result_t<FunctionTy, ElemTy>>
+List<ResultTy> makeList(ContainerTy &&container, FunctionTy &&func) {
+  List<ResultTy> v;
+  llvm::transform(container, std::back_inserter(v), func);
+  return v;
+}
+
+inline ObjectList makeList(const parser::OmpObjectList &objects,
+                           semantics::SemanticsContext &semaCtx) {
+  return makeList(objects.v, makeObjectF(semaCtx));
+}
+
+template <typename F, typename T, typename U = std::invoke_result_t<F, T>>
+std::optional<U> maybeApply(F &&func, const std::optional<T> &inp) {
+  if (!inp)
+    return std::nullopt;
+  return std::move(func(*inp));
+}
+
+std::optional<Object>
+getBaseObject(const Object &object,
+              Fortran::semantics::SemanticsContext &semaCtx);
+
+namespace clause {
+#ifdef EMPTY_CLASS
+#undef EMPTY_CLASS
+#endif
+#define EMPTY_CLASS(cls)                                                       \
+  using cls = tomp::clause::cls##T<SymIdent, SymReference>
+
+#ifdef WRAPPER_CLASS
+#undef WRAPPER_CLASS
+#endif
+#define WRAPPER_CLASS(cls, content)                                            \
+  [[maybe_unused]] extern int xyzzy_semicolon_absorber
+#define GEN_FLANG_CLAUSE_PARSER_CLASSES
+#include "llvm/Frontend/OpenMP/OMP.inc"
+#undef EMPTY_CLASS
+#undef WRAPPER_CLASS
+
+using Aligned = tomp::clause::AlignedT<SymIdent, SymReference>;
+using Allocate = tomp::clause::AllocateT<SymIdent, SymReference>;
+using Allocator = tomp::clause::AllocatorT<SymIdent, SymReference>;
+using AtomicDefaultMemOrder =
+    tomp::clause::AtomicDefaultMemOrderT<SymIdent, SymReference>;
+using Collapse = tomp::clause::CollapseT<SymIdent, SymReference>;
+using Copyin = tomp::clause::CopyinT<SymIdent, SymReference>;
+using Copyprivate = tomp::clause::CopyprivateT<SymIdent, SymReference>;
+using Defaultmap = tomp::clause::DefaultmapT<SymIdent, SymReference>;
+using Default = tomp::clause::DefaultT<SymIdent, SymReference>;
+using Depend = tomp::clause::DependT<SymIdent, SymReference>;
+using Device = tomp::clause::DeviceT<SymIdent, SymReference>;
+using DeviceType = tomp::clause::DeviceTypeT<SymIdent, SymReference>;
+using DistSchedule = tomp::clause::DistScheduleT<SymIdent, SymReference>;
+using Enter = tomp::clause::EnterT<SymIdent, SymReference>;
+using Filter = tomp::clause::FilterT<SymIdent, SymReference>;
+using Final = tomp::clause::FinalT<SymIdent, SymReference>;
+using Firstprivate = tomp::clause::FirstprivateT<SymIdent, SymReference>;
+using From = tomp::clause::FromT<SymIdent, SymReference>;
+using Grainsize = tomp::clause::GrainsizeT<SymIdent, SymReference>;
+using HasDeviceAddr = tomp::clause::HasDeviceAddrT<SymIdent, SymReference>;
+using Hint = tomp::clause::HintT<SymIdent, SymReference>;
+using If = tomp::clause::IfT<SymIdent, SymReference>;
+using InReduction = tomp::clause::InReductionT<SymIdent, SymReference>;
+using IsDevicePtr = tomp::clause::IsDevicePtrT<SymIdent, SymReference>;
+using Lastprivate = tomp::clause::LastprivateT<SymIdent, SymReference>;
+using Linear = tomp::clause::LinearT<SymIdent, SymReference>;
+using Link = tomp::clause::LinkT<SymIdent, SymReference>;
+using Map = tomp::clause::MapT<SymIdent, SymReference>;
+using Nocontext = tomp::clause::NocontextT<SymIdent, SymReference>;
+using Nontemporal = tomp::clause::NontemporalT<SymIdent, SymReference>;
+using Novariants = tomp::clause::NovariantsT<SymIdent, SymReference>;
+using NumTasks = tomp::clause::NumTasksT<SymIdent, SymReference>;
+using NumTeams = tomp::clause::NumTeamsT<SymIdent, SymReference>;
+using NumThreads = tomp::clause::NumThreadsT<SymIdent, SymReference>;
+using OmpxDynCgroupMem =
+    tomp::clause::OmpxDynCgroupMemT<SymIdent, SymReference>;
+using Ordered = tomp::clause::OrderedT<SymIdent, SymReference>;
+using Order = tomp::clause::OrderT<SymIdent, SymReference>;
+using Partial = tomp::clause::PartialT<SymIdent, SymReference>;
+using Priority = tomp::clause::PriorityT<SymIdent, SymReference>;
+using Private = tomp::clause::PrivateT<SymIdent, SymReference>;
+using ProcBind = tomp::clause::ProcBindT<SymIdent, SymReference>;
+using Reduction = tomp::clause::ReductionT<SymIdent, SymReference>;
+using Safelen = tomp::clause::SafelenT<SymIdent, SymReference>;
+using Schedule = tomp::clause::ScheduleT<SymIdent, SymReference>;
+using Shared = tomp::clause::SharedT<SymIdent, SymReference>;
+using Simdlen = tomp::clause::SimdlenT<SymIdent, SymReference>;
+using Sizes = tomp::clause::SizesT<SymIdent, SymReference>;
+using TaskReduction = tomp::clause::TaskReductionT<SymIdent, SymReference>;
+using ThreadLimit = tomp::clause::ThreadLimitT<SymIdent, SymReference>;
+using To = tomp::clause::ToT<SymIdent, SymReference>;
+using Uniform = tomp::clause::UniformT<SymIdent, SymReference>;
+using UseDeviceAddr = tomp::clause::UseDeviceAddrT<SymIdent, SymReference>;
+using UseDevicePtr = tomp::clause::UseDevicePtrT<SymIdent, SymReference>;
+} // namespace clause
+
+struct Clause : public tomp::ClauseT<SymIdent, SymReference> {
+  parser::CharBlock source;
+};
+
+template <typename Specific>
+Clause makeClause(llvm::omp::Clause id, Specific &&specific,
+                  parser::CharBlock source = {}) {
+  return Clause{id, specific, source};
+}
+
+Clause makeClause(const Fortran::parser::OmpClause &cls,
+                  semantics::SemanticsContext &semaCtx);
+
+List<Clause> makeList(const parser::OmpClauseList &clauses,
+                      semantics::SemanticsContext &semaCtx);
+} // namespace omp
+
+#endif // FORTRAN_LOWER_OPENMP_CLAUSES_H

>From fafbd98f05958d6983d87803b94536b9041b63dc Mon Sep 17 00:00:00 2001
From: Krzysztof Parzyszek <Krzysztof.Parzyszek at amd.com>
Date: Wed, 21 Feb 2024 14:26:11 -0600
Subject: [PATCH 2/3] [flang][OpenMP] Convert unique clauses in ClauseProcessor

Temporarily rename old clause list to `clauses2`, old clause iterator
to `ClauseIterator2`.
Change `findUniqueClause` to iterate over `omp::Clause` objects,
modify all handlers to operate on 'omp::clause::xyz` equivalents.
---
 flang/lib/Lower/OpenMP/ClauseProcessor.cpp | 211 +++++++++------------
 flang/lib/Lower/OpenMP/ClauseProcessor.h   |  36 +++-
 flang/lib/Lower/OpenMP/Clauses.cpp         |   6 +-
 flang/lib/Lower/OpenMP/Clauses.h           |  15 +-
 4 files changed, 129 insertions(+), 139 deletions(-)

diff --git a/flang/lib/Lower/OpenMP/ClauseProcessor.cpp b/flang/lib/Lower/OpenMP/ClauseProcessor.cpp
index a41f8312a28c9e..9987cd73fc7670 100644
--- a/flang/lib/Lower/OpenMP/ClauseProcessor.cpp
+++ b/flang/lib/Lower/OpenMP/ClauseProcessor.cpp
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "ClauseProcessor.h"
+#include "Clauses.h"
 
 #include "flang/Lower/PFTBuilder.h"
 #include "flang/Parser/tools.h"
@@ -30,64 +31,55 @@ static void checkMapType(mlir::Location location, mlir::Type type) {
 }
 
 static mlir::omp::ScheduleModifier
-translateScheduleModifier(const Fortran::parser::OmpScheduleModifierType &m) {
-  switch (m.v) {
-  case Fortran::parser::OmpScheduleModifierType::ModType::Monotonic:
+translateScheduleModifier(const omp::clause::Schedule::ModType &m) {
+  switch (m) {
+  case omp::clause::Schedule::ModType::Monotonic:
     return mlir::omp::ScheduleModifier::monotonic;
-  case Fortran::parser::OmpScheduleModifierType::ModType::Nonmonotonic:
+  case omp::clause::Schedule::ModType::Nonmonotonic:
     return mlir::omp::ScheduleModifier::nonmonotonic;
-  case Fortran::parser::OmpScheduleModifierType::ModType::Simd:
+  case omp::clause::Schedule::ModType::Simd:
     return mlir::omp::ScheduleModifier::simd;
   }
   return mlir::omp::ScheduleModifier::none;
 }
 
 static mlir::omp::ScheduleModifier
-getScheduleModifier(const Fortran::parser::OmpScheduleClause &x) {
-  const auto &modifier =
-      std::get<std::optional<Fortran::parser::OmpScheduleModifier>>(x.t);
+getScheduleModifier(const omp::clause::Schedule &clause) {
+  using ScheduleModifier = omp::clause::Schedule::ScheduleModifier;
+  const auto &modifier = std::get<std::optional<ScheduleModifier>>(clause.t);
   // The input may have the modifier any order, so we look for one that isn't
   // SIMD. If modifier is not set at all, fall down to the bottom and return
   // "none".
   if (modifier) {
-    const auto &modType1 =
-        std::get<Fortran::parser::OmpScheduleModifier::Modifier1>(modifier->t);
-    if (modType1.v.v ==
-        Fortran::parser::OmpScheduleModifierType::ModType::Simd) {
-      const auto &modType2 = std::get<
-          std::optional<Fortran::parser::OmpScheduleModifier::Modifier2>>(
-          modifier->t);
-      if (modType2 &&
-          modType2->v.v !=
-              Fortran::parser::OmpScheduleModifierType::ModType::Simd)
-        return translateScheduleModifier(modType2->v);
-
+    using ModType = omp::clause::Schedule::ModType;
+    const auto &modType1 = std::get<ModType>(modifier->t);
+    if (modType1 == ModType::Simd) {
+      const auto &modType2 = std::get<std::optional<ModType>>(modifier->t);
+      if (modType2 && *modType2 != ModType::Simd)
+        return translateScheduleModifier(*modType2);
       return mlir::omp::ScheduleModifier::none;
     }
 
-    return translateScheduleModifier(modType1.v);
+    return translateScheduleModifier(modType1);
   }
   return mlir::omp::ScheduleModifier::none;
 }
 
 static mlir::omp::ScheduleModifier
-getSimdModifier(const Fortran::parser::OmpScheduleClause &x) {
-  const auto &modifier =
-      std::get<std::optional<Fortran::parser::OmpScheduleModifier>>(x.t);
+getSimdModifier(const omp::clause::Schedule &clause) {
+  using ScheduleModifier = omp::clause::Schedule::ScheduleModifier;
+  const auto &modifier = std::get<std::optional<ScheduleModifier>>(clause.t);
   // Either of the two possible modifiers in the input can be the SIMD modifier,
   // so look in either one, and return simd if we find one. Not found = return
   // "none".
   if (modifier) {
-    const auto &modType1 =
-        std::get<Fortran::parser::OmpScheduleModifier::Modifier1>(modifier->t);
-    if (modType1.v.v == Fortran::parser::OmpScheduleModifierType::ModType::Simd)
+    using ModType = omp::clause::Schedule::ModType;
+    const auto &modType1 = std::get<ModType>(modifier->t);
+    if (modType1 == ModType::Simd)
       return mlir::omp::ScheduleModifier::simd;
 
-    const auto &modType2 = std::get<
-        std::optional<Fortran::parser::OmpScheduleModifier::Modifier2>>(
-        modifier->t);
-    if (modType2 && modType2->v.v ==
-                        Fortran::parser::OmpScheduleModifierType::ModType::Simd)
+    const auto &modType2 = std::get<std::optional<ModType>>(modifier->t);
+    if (modType2 && *modType2 == ModType::Simd)
       return mlir::omp::ScheduleModifier::simd;
   }
   return mlir::omp::ScheduleModifier::none;
@@ -141,21 +133,21 @@ genAllocateClause(Fortran::lower::AbstractConverter &converter,
   genObjectList(ompObjectList, converter, allocateOperands);
 }
 
-static mlir::omp::ClauseProcBindKindAttr genProcBindKindAttr(
-    fir::FirOpBuilder &firOpBuilder,
-    const Fortran::parser::OmpClause::ProcBind *procBindClause) {
+static mlir::omp::ClauseProcBindKindAttr
+genProcBindKindAttr(fir::FirOpBuilder &firOpBuilder,
+                    const omp::clause::ProcBind &clause) {
   mlir::omp::ClauseProcBindKind procBindKind;
-  switch (procBindClause->v.v) {
-  case Fortran::parser::OmpProcBindClause::Type::Master:
+  switch (clause.v) {
+  case omp::clause::ProcBind::Type::Master:
     procBindKind = mlir::omp::ClauseProcBindKind::Master;
     break;
-  case Fortran::parser::OmpProcBindClause::Type::Close:
+  case omp::clause::ProcBind::Type::Close:
     procBindKind = mlir::omp::ClauseProcBindKind::Close;
     break;
-  case Fortran::parser::OmpProcBindClause::Type::Spread:
+  case omp::clause::ProcBind::Type::Spread:
     procBindKind = mlir::omp::ClauseProcBindKind::Spread;
     break;
-  case Fortran::parser::OmpProcBindClause::Type::Primary:
+  case omp::clause::ProcBind::Type::Primary:
     procBindKind = mlir::omp::ClauseProcBindKind::Primary;
     break;
   }
@@ -253,9 +245,8 @@ bool ClauseProcessor::processCollapse(
   }
 
   std::int64_t collapseValue = 1l;
-  if (auto *collapseClause = findUniqueClause<ClauseTy::Collapse>()) {
-    const auto *expr = Fortran::semantics::GetExpr(collapseClause->v);
-    collapseValue = Fortran::evaluate::ToInt64(*expr).value();
+  if (auto *clause = findUniqueClause<omp::clause::Collapse>()) {
+    collapseValue = Fortran::evaluate::ToInt64(clause->v).value();
     found = true;
   }
 
@@ -294,19 +285,19 @@ bool ClauseProcessor::processCollapse(
 }
 
 bool ClauseProcessor::processDefault() const {
-  if (auto *defaultClause = findUniqueClause<ClauseTy::Default>()) {
+  if (auto *clause = findUniqueClause<omp::clause::Default>()) {
     // Private, Firstprivate, Shared, None
-    switch (defaultClause->v.v) {
-    case Fortran::parser::OmpDefaultClause::Type::Shared:
-    case Fortran::parser::OmpDefaultClause::Type::None:
+    switch (clause->v) {
+    case omp::clause::Default::Type::Shared:
+    case omp::clause::Default::Type::None:
       // Default clause with shared or none do not require any handling since
       // Shared is the default behavior in the IR and None is only required
       // for semantic checks.
       break;
-    case Fortran::parser::OmpDefaultClause::Type::Private:
+    case omp::clause::Default::Type::Private:
       // TODO Support default(private)
       break;
-    case Fortran::parser::OmpDefaultClause::Type::Firstprivate:
+    case omp::clause::Default::Type::Firstprivate:
       // TODO Support default(firstprivate)
       break;
     }
@@ -318,20 +309,17 @@ bool ClauseProcessor::processDefault() const {
 bool ClauseProcessor::processDevice(Fortran::lower::StatementContext &stmtCtx,
                                     mlir::Value &result) const {
   const Fortran::parser::CharBlock *source = nullptr;
-  if (auto *deviceClause = findUniqueClause<ClauseTy::Device>(&source)) {
+  if (auto *clause = findUniqueClause<omp::clause::Device>(&source)) {
     mlir::Location clauseLocation = converter.genLocation(*source);
-    if (auto deviceModifier = std::get<
-            std::optional<Fortran::parser::OmpDeviceClause::DeviceModifier>>(
-            deviceClause->v.t)) {
-      if (deviceModifier ==
-          Fortran::parser::OmpDeviceClause::DeviceModifier::Ancestor) {
+    if (auto deviceModifier =
+            std::get<std::optional<omp::clause::Device::DeviceModifier>>(
+                clause->t)) {
+      if (deviceModifier == omp::clause::Device::DeviceModifier::Ancestor) {
         TODO(clauseLocation, "OMPD_target Device Modifier Ancestor");
       }
     }
-    if (const auto *deviceExpr = Fortran::semantics::GetExpr(
-            std::get<Fortran::parser::ScalarIntExpr>(deviceClause->v.t))) {
-      result = fir::getBase(converter.genExprValue(*deviceExpr, stmtCtx));
-    }
+    const auto &deviceExpr = std::get<omp::SomeExpr>(clause->t);
+    result = fir::getBase(converter.genExprValue(deviceExpr, stmtCtx));
     return true;
   }
   return false;
@@ -339,16 +327,16 @@ bool ClauseProcessor::processDevice(Fortran::lower::StatementContext &stmtCtx,
 
 bool ClauseProcessor::processDeviceType(
     mlir::omp::DeclareTargetDeviceType &result) const {
-  if (auto *deviceTypeClause = findUniqueClause<ClauseTy::DeviceType>()) {
+  if (auto *clause = findUniqueClause<omp::clause::DeviceType>()) {
     // Case: declare target ... device_type(any | host | nohost)
-    switch (deviceTypeClause->v.v) {
-    case Fortran::parser::OmpDeviceTypeClause::Type::Nohost:
+    switch (clause->v) {
+    case omp::clause::DeviceType::Type::Nohost:
       result = mlir::omp::DeclareTargetDeviceType::nohost;
       break;
-    case Fortran::parser::OmpDeviceTypeClause::Type::Host:
+    case omp::clause::DeviceType::Type::Host:
       result = mlir::omp::DeclareTargetDeviceType::host;
       break;
-    case Fortran::parser::OmpDeviceTypeClause::Type::Any:
+    case omp::clause::DeviceType::Type::Any:
       result = mlir::omp::DeclareTargetDeviceType::any;
       break;
     }
@@ -360,12 +348,12 @@ bool ClauseProcessor::processDeviceType(
 bool ClauseProcessor::processFinal(Fortran::lower::StatementContext &stmtCtx,
                                    mlir::Value &result) const {
   const Fortran::parser::CharBlock *source = nullptr;
-  if (auto *finalClause = findUniqueClause<ClauseTy::Final>(&source)) {
+  if (auto *clause = findUniqueClause<omp::clause::Final>(&source)) {
     fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
     mlir::Location clauseLocation = converter.genLocation(*source);
 
-    mlir::Value finalVal = fir::getBase(converter.genExprValue(
-        *Fortran::semantics::GetExpr(finalClause->v), stmtCtx));
+    mlir::Value finalVal =
+        fir::getBase(converter.genExprValue(clause->v, stmtCtx));
     result = firOpBuilder.createConvert(clauseLocation,
                                         firOpBuilder.getI1Type(), finalVal);
     return true;
@@ -374,10 +362,9 @@ bool ClauseProcessor::processFinal(Fortran::lower::StatementContext &stmtCtx,
 }
 
 bool ClauseProcessor::processHint(mlir::IntegerAttr &result) const {
-  if (auto *hintClause = findUniqueClause<ClauseTy::Hint>()) {
+  if (auto *clause = findUniqueClause<omp::clause::Hint>()) {
     fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
-    const auto *expr = Fortran::semantics::GetExpr(hintClause->v);
-    int64_t hintValue = *Fortran::evaluate::ToInt64(*expr);
+    int64_t hintValue = *Fortran::evaluate::ToInt64(clause->v);
     result = firOpBuilder.getI64IntegerAttr(hintValue);
     return true;
   }
@@ -385,20 +372,19 @@ bool ClauseProcessor::processHint(mlir::IntegerAttr &result) const {
 }
 
 bool ClauseProcessor::processMergeable(mlir::UnitAttr &result) const {
-  return markClauseOccurrence<ClauseTy::Mergeable>(result);
+  return markClauseOccurrence<omp::clause::Mergeable>(result);
 }
 
 bool ClauseProcessor::processNowait(mlir::UnitAttr &result) const {
-  return markClauseOccurrence<ClauseTy::Nowait>(result);
+  return markClauseOccurrence<omp::clause::Nowait>(result);
 }
 
 bool ClauseProcessor::processNumTeams(Fortran::lower::StatementContext &stmtCtx,
                                       mlir::Value &result) const {
   // TODO Get lower and upper bounds for num_teams when parser is updated to
   // accept both.
-  if (auto *numTeamsClause = findUniqueClause<ClauseTy::NumTeams>()) {
-    result = fir::getBase(converter.genExprValue(
-        *Fortran::semantics::GetExpr(numTeamsClause->v), stmtCtx));
+  if (auto *clause = findUniqueClause<omp::clause::NumTeams>()) {
+    result = fir::getBase(converter.genExprValue(clause->v, stmtCtx));
     return true;
   }
   return false;
@@ -406,23 +392,20 @@ bool ClauseProcessor::processNumTeams(Fortran::lower::StatementContext &stmtCtx,
 
 bool ClauseProcessor::processNumThreads(
     Fortran::lower::StatementContext &stmtCtx, mlir::Value &result) const {
-  if (auto *numThreadsClause = findUniqueClause<ClauseTy::NumThreads>()) {
+  if (auto *clause = findUniqueClause<omp::clause::NumThreads>()) {
     // OMPIRBuilder expects `NUM_THREADS` clause as a `Value`.
-    result = fir::getBase(converter.genExprValue(
-        *Fortran::semantics::GetExpr(numThreadsClause->v), stmtCtx));
+    result = fir::getBase(converter.genExprValue(clause->v, stmtCtx));
     return true;
   }
   return false;
 }
 
 bool ClauseProcessor::processOrdered(mlir::IntegerAttr &result) const {
-  if (auto *orderedClause = findUniqueClause<ClauseTy::Ordered>()) {
+  if (auto *clause = findUniqueClause<omp::clause::Ordered>()) {
     fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
     int64_t orderedClauseValue = 0l;
-    if (orderedClause->v.has_value()) {
-      const auto *expr = Fortran::semantics::GetExpr(orderedClause->v);
-      orderedClauseValue = *Fortran::evaluate::ToInt64(*expr);
-    }
+    if (clause->v.has_value())
+      orderedClauseValue = *Fortran::evaluate::ToInt64(*clause->v);
     result = firOpBuilder.getI64IntegerAttr(orderedClauseValue);
     return true;
   }
@@ -431,9 +414,8 @@ bool ClauseProcessor::processOrdered(mlir::IntegerAttr &result) const {
 
 bool ClauseProcessor::processPriority(Fortran::lower::StatementContext &stmtCtx,
                                       mlir::Value &result) const {
-  if (auto *priorityClause = findUniqueClause<ClauseTy::Priority>()) {
-    result = fir::getBase(converter.genExprValue(
-        *Fortran::semantics::GetExpr(priorityClause->v), stmtCtx));
+  if (auto *clause = findUniqueClause<omp::clause::Priority>()) {
+    result = fir::getBase(converter.genExprValue(clause->v, stmtCtx));
     return true;
   }
   return false;
@@ -441,20 +423,19 @@ bool ClauseProcessor::processPriority(Fortran::lower::StatementContext &stmtCtx,
 
 bool ClauseProcessor::processProcBind(
     mlir::omp::ClauseProcBindKindAttr &result) const {
-  if (auto *procBindClause = findUniqueClause<ClauseTy::ProcBind>()) {
+  if (auto *clause = findUniqueClause<omp::clause::ProcBind>()) {
     fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
-    result = genProcBindKindAttr(firOpBuilder, procBindClause);
+    result = genProcBindKindAttr(firOpBuilder, *clause);
     return true;
   }
   return false;
 }
 
 bool ClauseProcessor::processSafelen(mlir::IntegerAttr &result) const {
-  if (auto *safelenClause = findUniqueClause<ClauseTy::Safelen>()) {
+  if (auto *clause = findUniqueClause<omp::clause::Safelen>()) {
     fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
-    const auto *expr = Fortran::semantics::GetExpr(safelenClause->v);
     const std::optional<std::int64_t> safelenVal =
-        Fortran::evaluate::ToInt64(*expr);
+        Fortran::evaluate::ToInt64(clause->v);
     result = firOpBuilder.getI64IntegerAttr(*safelenVal);
     return true;
   }
@@ -465,41 +446,38 @@ bool ClauseProcessor::processSchedule(
     mlir::omp::ClauseScheduleKindAttr &valAttr,
     mlir::omp::ScheduleModifierAttr &modifierAttr,
     mlir::UnitAttr &simdModifierAttr) const {
-  if (auto *scheduleClause = findUniqueClause<ClauseTy::Schedule>()) {
+  if (auto *clause = findUniqueClause<omp::clause::Schedule>()) {
     fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
     mlir::MLIRContext *context = firOpBuilder.getContext();
-    const Fortran::parser::OmpScheduleClause &scheduleType = scheduleClause->v;
-    const auto &scheduleClauseKind =
-        std::get<Fortran::parser::OmpScheduleClause::ScheduleType>(
-            scheduleType.t);
+    const auto &scheduleType =
+        std::get<omp::clause::Schedule::ScheduleType>(clause->t);
 
     mlir::omp::ClauseScheduleKind scheduleKind;
-    switch (scheduleClauseKind) {
-    case Fortran::parser::OmpScheduleClause::ScheduleType::Static:
+    switch (scheduleType) {
+    case omp::clause::Schedule::ScheduleType::Static:
       scheduleKind = mlir::omp::ClauseScheduleKind::Static;
       break;
-    case Fortran::parser::OmpScheduleClause::ScheduleType::Dynamic:
+    case omp::clause::Schedule::ScheduleType::Dynamic:
       scheduleKind = mlir::omp::ClauseScheduleKind::Dynamic;
       break;
-    case Fortran::parser::OmpScheduleClause::ScheduleType::Guided:
+    case omp::clause::Schedule::ScheduleType::Guided:
       scheduleKind = mlir::omp::ClauseScheduleKind::Guided;
       break;
-    case Fortran::parser::OmpScheduleClause::ScheduleType::Auto:
+    case omp::clause::Schedule::ScheduleType::Auto:
       scheduleKind = mlir::omp::ClauseScheduleKind::Auto;
       break;
-    case Fortran::parser::OmpScheduleClause::ScheduleType::Runtime:
+    case omp::clause::Schedule::ScheduleType::Runtime:
       scheduleKind = mlir::omp::ClauseScheduleKind::Runtime;
       break;
     }
 
-    mlir::omp::ScheduleModifier scheduleModifier =
-        getScheduleModifier(scheduleClause->v);
+    mlir::omp::ScheduleModifier scheduleModifier = getScheduleModifier(*clause);
 
     if (scheduleModifier != mlir::omp::ScheduleModifier::none)
       modifierAttr =
           mlir::omp::ScheduleModifierAttr::get(context, scheduleModifier);
 
-    if (getSimdModifier(scheduleClause->v) != mlir::omp::ScheduleModifier::none)
+    if (getSimdModifier(*clause) != mlir::omp::ScheduleModifier::none)
       simdModifierAttr = firOpBuilder.getUnitAttr();
 
     valAttr = mlir::omp::ClauseScheduleKindAttr::get(context, scheduleKind);
@@ -510,25 +488,19 @@ bool ClauseProcessor::processSchedule(
 
 bool ClauseProcessor::processScheduleChunk(
     Fortran::lower::StatementContext &stmtCtx, mlir::Value &result) const {
-  if (auto *scheduleClause = findUniqueClause<ClauseTy::Schedule>()) {
-    if (const auto &chunkExpr =
-            std::get<std::optional<Fortran::parser::ScalarIntExpr>>(
-                scheduleClause->v.t)) {
-      if (const auto *expr = Fortran::semantics::GetExpr(*chunkExpr)) {
-        result = fir::getBase(converter.genExprValue(*expr, stmtCtx));
-      }
-    }
+  if (auto *clause = findUniqueClause<omp::clause::Schedule>()) {
+    if (const auto &chunkExpr = std::get<omp::MaybeExpr>(clause->t))
+      result = fir::getBase(converter.genExprValue(*chunkExpr, stmtCtx));
     return true;
   }
   return false;
 }
 
 bool ClauseProcessor::processSimdlen(mlir::IntegerAttr &result) const {
-  if (auto *simdlenClause = findUniqueClause<ClauseTy::Simdlen>()) {
+  if (auto *clause = findUniqueClause<omp::clause::Simdlen>()) {
     fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
-    const auto *expr = Fortran::semantics::GetExpr(simdlenClause->v);
     const std::optional<std::int64_t> simdlenVal =
-        Fortran::evaluate::ToInt64(*expr);
+        Fortran::evaluate::ToInt64(clause->v);
     result = firOpBuilder.getI64IntegerAttr(*simdlenVal);
     return true;
   }
@@ -537,16 +509,15 @@ bool ClauseProcessor::processSimdlen(mlir::IntegerAttr &result) const {
 
 bool ClauseProcessor::processThreadLimit(
     Fortran::lower::StatementContext &stmtCtx, mlir::Value &result) const {
-  if (auto *threadLmtClause = findUniqueClause<ClauseTy::ThreadLimit>()) {
-    result = fir::getBase(converter.genExprValue(
-        *Fortran::semantics::GetExpr(threadLmtClause->v), stmtCtx));
+  if (auto *clause = findUniqueClause<omp::clause::ThreadLimit>()) {
+    result = fir::getBase(converter.genExprValue(clause->v, stmtCtx));
     return true;
   }
   return false;
 }
 
 bool ClauseProcessor::processUntied(mlir::UnitAttr &result) const {
-  return markClauseOccurrence<ClauseTy::Untied>(result);
+  return markClauseOccurrence<omp::clause::Untied>(result);
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/flang/lib/Lower/OpenMP/ClauseProcessor.h b/flang/lib/Lower/OpenMP/ClauseProcessor.h
index 11aff0be25053d..c87fc30c88bb93 100644
--- a/flang/lib/Lower/OpenMP/ClauseProcessor.h
+++ b/flang/lib/Lower/OpenMP/ClauseProcessor.h
@@ -12,6 +12,7 @@
 #ifndef FORTRAN_LOWER_CLAUASEPROCESSOR_H
 #define FORTRAN_LOWER_CLAUASEPROCESSOR_H
 
+#include "Clauses.h"
 #include "DirectivesCommon.h"
 #include "ReductionProcessor.h"
 #include "Utils.h"
@@ -51,7 +52,8 @@ class ClauseProcessor {
   ClauseProcessor(Fortran::lower::AbstractConverter &converter,
                   Fortran::semantics::SemanticsContext &semaCtx,
                   const Fortran::parser::OmpClauseList &clauses)
-      : converter(converter), semaCtx(semaCtx), clauses(clauses) {}
+      : converter(converter), semaCtx(semaCtx), clauses2(clauses),
+        clauses(makeList(clauses, semaCtx)) {}
 
   // 'Unique' clauses: They can appear at most once in the clause list.
   bool
@@ -155,11 +157,15 @@ class ClauseProcessor {
                    llvm::omp::Directive directive) const;
 
 private:
-  using ClauseIterator = std::list<ClauseTy>::const_iterator;
+  using ClauseIterator = List<Clause>::const_iterator;
+  using ClauseIterator2 = std::list<ClauseTy>::const_iterator;
 
   /// Utility to find a clause within a range in the clause list.
   template <typename T>
   static ClauseIterator findClause(ClauseIterator begin, ClauseIterator end);
+  template <typename T>
+  static ClauseIterator2 findClause2(ClauseIterator2 begin,
+                                     ClauseIterator2 end);
 
   /// Return the first instance of the given clause found in the clause list or
   /// `nullptr` if not present. If more than one instance is expected, use
@@ -181,7 +187,8 @@ class ClauseProcessor {
 
   Fortran::lower::AbstractConverter &converter;
   Fortran::semantics::SemanticsContext &semaCtx;
-  const Fortran::parser::OmpClauseList &clauses;
+  const Fortran::parser::OmpClauseList &clauses2;
+  List<Clause> clauses;
 };
 
 template <typename T>
@@ -248,7 +255,7 @@ void ClauseProcessor::processTODO(mlir::Location currentLocation,
              " construct");
   };
 
-  for (ClauseIterator it = clauses.v.begin(); it != clauses.v.end(); ++it)
+  for (ClauseIterator2 it = clauses2.v.begin(); it != clauses2.v.end(); ++it)
     (checkUnhandledClause(std::get_if<Ts>(&it->u)), ...);
 }
 
@@ -263,11 +270,22 @@ ClauseProcessor::findClause(ClauseIterator begin, ClauseIterator end) {
   return end;
 }
 
+template <typename T>
+ClauseProcessor::ClauseIterator2
+ClauseProcessor::findClause2(ClauseIterator2 begin, ClauseIterator2 end) {
+  for (ClauseIterator2 it = begin; it != end; ++it) {
+    if (std::get_if<T>(&it->u))
+      return it;
+  }
+
+  return end;
+}
+
 template <typename T>
 const T *ClauseProcessor::findUniqueClause(
     const Fortran::parser::CharBlock **source) const {
-  ClauseIterator it = findClause<T>(clauses.v.begin(), clauses.v.end());
-  if (it != clauses.v.end()) {
+  ClauseIterator it = findClause<T>(clauses.begin(), clauses.end());
+  if (it != clauses.end()) {
     if (source)
       *source = &it->source;
     return &std::get<T>(it->u);
@@ -280,9 +298,9 @@ bool ClauseProcessor::findRepeatableClause(
     std::function<void(const T *, const Fortran::parser::CharBlock &source)>
         callbackFn) const {
   bool found = false;
-  ClauseIterator nextIt, endIt = clauses.v.end();
-  for (ClauseIterator it = clauses.v.begin(); it != endIt; it = nextIt) {
-    nextIt = findClause<T>(it, endIt);
+  ClauseIterator2 nextIt, endIt = clauses2.v.end();
+  for (ClauseIterator2 it = clauses2.v.begin(); it != endIt; it = nextIt) {
+    nextIt = findClause2<T>(it, endIt);
 
     if (nextIt != endIt) {
       callbackFn(&std::get<T>(nextIt->u), nextIt->source);
diff --git a/flang/lib/Lower/OpenMP/Clauses.cpp b/flang/lib/Lower/OpenMP/Clauses.cpp
index dd7ce71f6ddca4..0b90b705b9e406 100644
--- a/flang/lib/Lower/OpenMP/Clauses.cpp
+++ b/flang/lib/Lower/OpenMP/Clauses.cpp
@@ -42,7 +42,7 @@ static llvm::omp::Clause getClauseId(const Fortran::parser::OmpClause &clause) {
                     clause.u);
 }
 
-namespace omp {
+namespace Fortran::lower::omp {
 using SymbolWithDesignator = std::tuple<semantics::Symbol *, MaybeExpr>;
 
 struct SymDsgExtractor {
@@ -718,10 +718,10 @@ Clause makeClause(const Fortran::parser::OmpClause &cls,
       cls.u);
 }
 
-omp::List<Clause> makeList(const parser::OmpClauseList &clauses,
+List<Clause> makeList(const parser::OmpClauseList &clauses,
                            semantics::SemanticsContext &semaCtx) {
   return makeList(clauses.v, [&](const parser::OmpClause &s) {
     return makeClause(s, semaCtx);
   });
 }
-} // namespace omp
+} // namespace Fortran::lower::omp
diff --git a/flang/lib/Lower/OpenMP/Clauses.h b/flang/lib/Lower/OpenMP/Clauses.h
index e40663565ae603..a7e563f4b0f90b 100644
--- a/flang/lib/Lower/OpenMP/Clauses.h
+++ b/flang/lib/Lower/OpenMP/Clauses.h
@@ -22,7 +22,7 @@
 #include <type_traits>
 #include <utility>
 
-namespace omp {
+namespace Fortran::lower::omp {
 using namespace Fortran;
 using SomeType = evaluate::SomeType;
 using SomeExpr = semantics::SomeExpr;
@@ -33,13 +33,14 @@ using SymReference = SomeExpr;
 
 template <typename T>
 using List = tomp::ListT<T>;
-} // namespace omp
+} // namespace Fortran::lower::omp
 
 namespace tomp {
 template <>
-struct ObjectT<omp::SymIdent, omp::SymReference> {
-  using IdType = omp::SymIdent;
-  using ExprType = omp::SymReference;
+struct ObjectT<Fortran::lower::omp::SymIdent,
+               Fortran::lower::omp::SymReference> {
+  using IdType = Fortran::lower::omp::SymIdent;
+  using ExprType = Fortran::lower::omp::SymReference;
 
   const IdType &id() const { return symbol; }
   const std::optional<ExprType> &ref() const { return designator; }
@@ -49,7 +50,7 @@ struct ObjectT<omp::SymIdent, omp::SymReference> {
 };
 } // namespace tomp
 
-namespace omp {
+namespace Fortran::lower::omp {
 
 using Object = tomp::ObjectT<SymIdent, SymReference>;
 using ObjectList = tomp::ObjectListT<SymIdent, SymReference>;
@@ -193,6 +194,6 @@ Clause makeClause(const Fortran::parser::OmpClause &cls,
 
 List<Clause> makeList(const parser::OmpClauseList &clauses,
                       semantics::SemanticsContext &semaCtx);
-} // namespace omp
+} // namespace Fortran::lower::omp
 
 #endif // FORTRAN_LOWER_OPENMP_CLAUSES_H

>From 655dce519efb87f8d3babf3b7a5d6132bb82e2a6 Mon Sep 17 00:00:00 2001
From: Krzysztof Parzyszek <Krzysztof.Parzyszek at amd.com>
Date: Wed, 21 Feb 2024 15:51:38 -0600
Subject: [PATCH 3/3] [flang][OpenMP] Convert repeatable clauses (except Map)
 in ClauseProcessor

Rename `findRepeatableClause` to `findRepeatableClause2`, and make the
new `findRepeatableClause` operate on new `omp::Clause` objects.

Leave `Map` unchanged, because it will require more changes for it to
work.
---
 flang/include/flang/Evaluate/tools.h          |  23 ++
 flang/lib/Lower/OpenMP/ClauseProcessor.cpp    | 218 ++++++++----------
 flang/lib/Lower/OpenMP/ClauseProcessor.h      |  29 ++-
 flang/lib/Lower/OpenMP/Clauses.cpp            |   6 -
 flang/lib/Lower/OpenMP/Clauses.h              |   6 +
 flang/lib/Lower/OpenMP/OpenMP.cpp             | 182 +++++++--------
 flang/lib/Lower/OpenMP/ReductionProcessor.cpp | 155 ++++++-------
 flang/lib/Lower/OpenMP/ReductionProcessor.h   |  23 +-
 flang/lib/Lower/OpenMP/Utils.cpp              |  41 ++--
 flang/lib/Lower/OpenMP/Utils.h                |  10 +-
 10 files changed, 348 insertions(+), 345 deletions(-)

diff --git a/flang/include/flang/Evaluate/tools.h b/flang/include/flang/Evaluate/tools.h
index d257da1a709642..e9999974944e88 100644
--- a/flang/include/flang/Evaluate/tools.h
+++ b/flang/include/flang/Evaluate/tools.h
@@ -430,6 +430,29 @@ template <typename A> std::optional<CoarrayRef> ExtractCoarrayRef(const A &x) {
   }
 }
 
+struct ExtractSubstringHelper {
+  template <typename T> static std::optional<Substring> visit(T &&) {
+    return std::nullopt;
+  }
+
+  static std::optional<Substring> visit(const Substring &e) { return e; }
+
+  template <typename T>
+  static std::optional<Substring> visit(const Designator<T> &e) {
+    return std::visit([](auto &&s) { return visit(s); }, e.u);
+  }
+
+  template <typename T>
+  static std::optional<Substring> visit(const Expr<T> &e) {
+    return std::visit([](auto &&s) { return visit(s); }, e.u);
+  }
+};
+
+template <typename A>
+std::optional<Substring> ExtractSubstring(const A &x) {
+  return ExtractSubstringHelper::visit(x);
+}
+
 // If an expression is simply a whole symbol data designator,
 // extract and return that symbol, else null.
 template <typename A> const Symbol *UnwrapWholeSymbolDataRef(const A &x) {
diff --git a/flang/lib/Lower/OpenMP/ClauseProcessor.cpp b/flang/lib/Lower/OpenMP/ClauseProcessor.cpp
index 9987cd73fc7670..6e45a939333d62 100644
--- a/flang/lib/Lower/OpenMP/ClauseProcessor.cpp
+++ b/flang/lib/Lower/OpenMP/ClauseProcessor.cpp
@@ -87,7 +87,7 @@ getSimdModifier(const omp::clause::Schedule &clause) {
 
 static void
 genAllocateClause(Fortran::lower::AbstractConverter &converter,
-                  const Fortran::parser::OmpAllocateClause &ompAllocateClause,
+                  const omp::clause::Allocate &clause,
                   llvm::SmallVectorImpl<mlir::Value> &allocatorOperands,
                   llvm::SmallVectorImpl<mlir::Value> &allocateOperands) {
   fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
@@ -95,21 +95,18 @@ genAllocateClause(Fortran::lower::AbstractConverter &converter,
   Fortran::lower::StatementContext stmtCtx;
 
   mlir::Value allocatorOperand;
-  const Fortran::parser::OmpObjectList &ompObjectList =
-      std::get<Fortran::parser::OmpObjectList>(ompAllocateClause.t);
-  const auto &allocateModifier = std::get<
-      std::optional<Fortran::parser::OmpAllocateClause::AllocateModifier>>(
-      ompAllocateClause.t);
+  const omp::ObjectList &objectList = std::get<omp::ObjectList>(clause.t);
+  const auto &modifier =
+      std::get<std::optional<omp::clause::Allocate::Modifier>>(clause.t);
 
   // If the allocate modifier is present, check if we only use the allocator
   // submodifier.  ALIGN in this context is unimplemented
   const bool onlyAllocator =
-      allocateModifier &&
-      std::holds_alternative<
-          Fortran::parser::OmpAllocateClause::AllocateModifier::Allocator>(
-          allocateModifier->u);
+      modifier &&
+      std::holds_alternative<omp::clause::Allocate::Modifier::Allocator>(
+          modifier->u);
 
-  if (allocateModifier && !onlyAllocator) {
+  if (modifier && !onlyAllocator) {
     TODO(currentLocation, "OmpAllocateClause ALIGN modifier");
   }
 
@@ -117,20 +114,17 @@ genAllocateClause(Fortran::lower::AbstractConverter &converter,
   // to list of allocators, otherwise, add default allocator to
   // list of allocators.
   if (onlyAllocator) {
-    const auto &allocatorValue = std::get<
-        Fortran::parser::OmpAllocateClause::AllocateModifier::Allocator>(
-        allocateModifier->u);
-    allocatorOperand = fir::getBase(converter.genExprValue(
-        *Fortran::semantics::GetExpr(allocatorValue.v), stmtCtx));
-    allocatorOperands.insert(allocatorOperands.end(), ompObjectList.v.size(),
-                             allocatorOperand);
+    const auto &value =
+        std::get<omp::clause::Allocate::Modifier::Allocator>(modifier->u);
+    mlir::Value operand =
+        fir::getBase(converter.genExprValue(value.v, stmtCtx));
+    allocatorOperands.append(objectList.size(), operand);
   } else {
-    allocatorOperand = firOpBuilder.createIntegerConstant(
+    mlir::Value operand = firOpBuilder.createIntegerConstant(
         currentLocation, firOpBuilder.getI32Type(), 1);
-    allocatorOperands.insert(allocatorOperands.end(), ompObjectList.v.size(),
-                             allocatorOperand);
+    allocatorOperands.append(objectList.size(), operand);
   }
-  genObjectList(ompObjectList, converter, allocateOperands);
+  genObjectList(objectList, converter, allocateOperands);
 }
 
 static mlir::omp::ClauseProcBindKindAttr
@@ -157,20 +151,17 @@ genProcBindKindAttr(fir::FirOpBuilder &firOpBuilder,
 
 static mlir::omp::ClauseTaskDependAttr
 genDependKindAttr(fir::FirOpBuilder &firOpBuilder,
-                  const Fortran::parser::OmpClause::Depend *dependClause) {
+                  const omp::clause::Depend &clause) {
   mlir::omp::ClauseTaskDepend pbKind;
-  switch (
-      std::get<Fortran::parser::OmpDependenceType>(
-          std::get<Fortran::parser::OmpDependClause::InOut>(dependClause->v.u)
-              .t)
-          .v) {
-  case Fortran::parser::OmpDependenceType::Type::In:
+  const auto &inOut = std::get<omp::clause::Depend::InOut>(clause.u);
+  switch (std::get<omp::clause::Depend::Type>(inOut.t)) {
+  case omp::clause::Depend::Type::In:
     pbKind = mlir::omp::ClauseTaskDepend::taskdependin;
     break;
-  case Fortran::parser::OmpDependenceType::Type::Out:
+  case omp::clause::Depend::Type::Out:
     pbKind = mlir::omp::ClauseTaskDepend::taskdependout;
     break;
-  case Fortran::parser::OmpDependenceType::Type::Inout:
+  case omp::clause::Depend::Type::Inout:
     pbKind = mlir::omp::ClauseTaskDepend::taskdependinout;
     break;
   default:
@@ -181,45 +172,41 @@ genDependKindAttr(fir::FirOpBuilder &firOpBuilder,
                                               pbKind);
 }
 
-static mlir::Value getIfClauseOperand(
-    Fortran::lower::AbstractConverter &converter,
-    const Fortran::parser::OmpClause::If *ifClause,
-    Fortran::parser::OmpIfClause::DirectiveNameModifier directiveName,
-    mlir::Location clauseLocation) {
+static mlir::Value
+getIfClauseOperand(Fortran::lower::AbstractConverter &converter,
+                   const omp::clause::If &clause,
+                   omp::clause::If::DirectiveNameModifier directiveName,
+                   mlir::Location clauseLocation) {
   // Only consider the clause if it's intended for the given directive.
-  auto &directive = std::get<
-      std::optional<Fortran::parser::OmpIfClause::DirectiveNameModifier>>(
-      ifClause->v.t);
+  auto &directive =
+      std::get<std::optional<omp::clause::If::DirectiveNameModifier>>(clause.t);
   if (directive && directive.value() != directiveName)
     return nullptr;
 
   Fortran::lower::StatementContext stmtCtx;
   fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
-  auto &expr = std::get<Fortran::parser::ScalarLogicalExpr>(ifClause->v.t);
   mlir::Value ifVal = fir::getBase(
-      converter.genExprValue(*Fortran::semantics::GetExpr(expr), stmtCtx));
+      converter.genExprValue(std::get<omp::SomeExpr>(clause.t), stmtCtx));
   return firOpBuilder.createConvert(clauseLocation, firOpBuilder.getI1Type(),
                                     ifVal);
 }
 
 static void
 addUseDeviceClause(Fortran::lower::AbstractConverter &converter,
-                   const Fortran::parser::OmpObjectList &useDeviceClause,
+                   const omp::ObjectList &objects,
                    llvm::SmallVectorImpl<mlir::Value> &operands,
                    llvm::SmallVectorImpl<mlir::Type> &useDeviceTypes,
                    llvm::SmallVectorImpl<mlir::Location> &useDeviceLocs,
                    llvm::SmallVectorImpl<const Fortran::semantics::Symbol *>
                        &useDeviceSymbols) {
-  genObjectList(useDeviceClause, converter, operands);
+  genObjectList(objects, converter, operands);
   for (mlir::Value &operand : operands) {
     checkMapType(operand.getLoc(), operand.getType());
     useDeviceTypes.push_back(operand.getType());
     useDeviceLocs.push_back(operand.getLoc());
   }
-  for (const Fortran::parser::OmpObject &ompObject : useDeviceClause.v) {
-    Fortran::semantics::Symbol *sym = getOmpObjectSymbol(ompObject);
-    useDeviceSymbols.push_back(sym);
-  }
+  for (const omp::Object &object : objects)
+    useDeviceSymbols.push_back(object.id());
 }
 
 //===----------------------------------------------------------------------===//
@@ -527,10 +514,10 @@ bool ClauseProcessor::processUntied(mlir::UnitAttr &result) const {
 bool ClauseProcessor::processAllocate(
     llvm::SmallVectorImpl<mlir::Value> &allocatorOperands,
     llvm::SmallVectorImpl<mlir::Value> &allocateOperands) const {
-  return findRepeatableClause<ClauseTy::Allocate>(
-      [&](const ClauseTy::Allocate *allocateClause,
+  return findRepeatableClause<omp::clause::Allocate>(
+      [&](const omp::clause::Allocate &clause,
           const Fortran::parser::CharBlock &) {
-        genAllocateClause(converter, allocateClause->v, allocatorOperands,
+        genAllocateClause(converter, clause, allocatorOperands,
                           allocateOperands);
       });
 }
@@ -547,12 +534,12 @@ bool ClauseProcessor::processCopyin() const {
         if (converter.isPresentShallowLookup(*sym))
           converter.copyHostAssociateVar(*sym, copyAssignIP);
       };
-  bool hasCopyin = findRepeatableClause<ClauseTy::Copyin>(
-      [&](const ClauseTy::Copyin *copyinClause,
+  bool hasCopyin = findRepeatableClause<omp::clause::Copyin>(
+      [&](const omp::clause::Copyin &clause,
           const Fortran::parser::CharBlock &) {
-        const Fortran::parser::OmpObjectList &ompObjectList = copyinClause->v;
-        for (const Fortran::parser::OmpObject &ompObject : ompObjectList.v) {
-          Fortran::semantics::Symbol *sym = getOmpObjectSymbol(ompObject);
+        for (const omp::Object &object : clause.v) {
+          Fortran::semantics::Symbol *sym = object.id();
+          assert(sym && "Expecting symbol");
           if (const auto *commonDetails =
                   sym->detailsIf<Fortran::semantics::CommonBlockDetails>()) {
             for (const auto &mem : commonDetails->objects())
@@ -716,13 +703,11 @@ bool ClauseProcessor::processCopyPrivate(
     copyPrivateFuncs.push_back(mlir::SymbolRefAttr::get(funcOp));
   };
 
-  bool hasCopyPrivate = findRepeatableClause<ClauseTy::Copyprivate>(
-      [&](const ClauseTy::Copyprivate *copyPrivateClause,
+  bool hasCopyPrivate = findRepeatableClause<clause::Copyprivate>(
+      [&](const clause::Copyprivate &clause,
           const Fortran::parser::CharBlock &) {
-        const Fortran::parser::OmpObjectList &ompObjectList =
-            copyPrivateClause->v;
-        for (const Fortran::parser::OmpObject &ompObject : ompObjectList.v) {
-          Fortran::semantics::Symbol *sym = getOmpObjectSymbol(ompObject);
+        for (const Object &object : clause.v) {
+          Fortran::semantics::Symbol *sym = object.id();
           if (const auto *commonDetails =
                   sym->detailsIf<Fortran::semantics::CommonBlockDetails>()) {
             for (const auto &mem : commonDetails->objects())
@@ -741,38 +726,30 @@ bool ClauseProcessor::processDepend(
     llvm::SmallVectorImpl<mlir::Value> &dependOperands) const {
   fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
 
-  return findRepeatableClause<ClauseTy::Depend>(
-      [&](const ClauseTy::Depend *dependClause,
+  return findRepeatableClause<omp::clause::Depend>(
+      [&](const omp::clause::Depend &clause,
           const Fortran::parser::CharBlock &) {
-        const std::list<Fortran::parser::Designator> &depVal =
-            std::get<std::list<Fortran::parser::Designator>>(
-                std::get<Fortran::parser::OmpDependClause::InOut>(
-                    dependClause->v.u)
-                    .t);
+        assert(std::holds_alternative<omp::clause::Depend::InOut>(clause.u) &&
+               "Only InOut is handled at the moment");
+        const auto &inOut = std::get<omp::clause::Depend::InOut>(clause.u);
+        const auto &objects = std::get<omp::ObjectList>(inOut.t);
+
         mlir::omp::ClauseTaskDependAttr dependTypeOperand =
-            genDependKindAttr(firOpBuilder, dependClause);
-        dependTypeOperands.insert(dependTypeOperands.end(), depVal.size(),
-                                  dependTypeOperand);
-        for (const Fortran::parser::Designator &ompObject : depVal) {
-          Fortran::semantics::Symbol *sym = nullptr;
-          std::visit(
-              Fortran::common::visitors{
-                  [&](const Fortran::parser::DataRef &designator) {
-                    if (const Fortran::parser::Name *name =
-                            std::get_if<Fortran::parser::Name>(&designator.u)) {
-                      sym = name->symbol;
-                    } else if (std::get_if<Fortran::common::Indirection<
-                                   Fortran::parser::ArrayElement>>(
-                                   &designator.u)) {
-                      TODO(converter.getCurrentLocation(),
-                           "array sections not supported for task depend");
-                    }
-                  },
-                  [&](const Fortran::parser::Substring &designator) {
-                    TODO(converter.getCurrentLocation(),
-                         "substring not supported for task depend");
-                  }},
-              (ompObject).u);
+            genDependKindAttr(firOpBuilder, clause);
+        dependTypeOperands.append(objects.size(), dependTypeOperand);
+
+        for (const omp::Object &object : objects) {
+          assert(object.ref() && "Expecting designator");
+
+          if (Fortran::evaluate::ExtractSubstring(*object.ref())) {
+            TODO(converter.getCurrentLocation(),
+                 "substring not supported for task depend");
+          } else if (Fortran::evaluate::IsArrayElement(*object.ref())) {
+            TODO(converter.getCurrentLocation(),
+                 "array sections not supported for task depend");
+          }
+
+          Fortran::semantics::Symbol *sym = object.id();
           const mlir::Value variable = converter.getSymbolAddress(*sym);
           dependOperands.push_back(variable);
         }
@@ -780,14 +757,14 @@ bool ClauseProcessor::processDepend(
 }
 
 bool ClauseProcessor::processIf(
-    Fortran::parser::OmpIfClause::DirectiveNameModifier directiveName,
+    omp::clause::If::DirectiveNameModifier directiveName,
     mlir::Value &result) const {
   bool found = false;
-  findRepeatableClause<ClauseTy::If>(
-      [&](const ClauseTy::If *ifClause,
+  findRepeatableClause<omp::clause::If>(
+      [&](const omp::clause::If &clause,
           const Fortran::parser::CharBlock &source) {
         mlir::Location clauseLocation = converter.genLocation(source);
-        mlir::Value operand = getIfClauseOperand(converter, ifClause,
+        mlir::Value operand = getIfClauseOperand(converter, clause,
                                                  directiveName, clauseLocation);
         // Assume that, at most, a single 'if' clause will be applicable to the
         // given directive.
@@ -801,12 +778,11 @@ bool ClauseProcessor::processIf(
 
 bool ClauseProcessor::processLink(
     llvm::SmallVectorImpl<DeclareTargetCapturePair> &result) const {
-  return findRepeatableClause<ClauseTy::Link>(
-      [&](const ClauseTy::Link *linkClause,
-          const Fortran::parser::CharBlock &) {
+  return findRepeatableClause<omp::clause::Link>(
+      [&](const omp::clause::Link &clause, const Fortran::parser::CharBlock &) {
         // Case: declare target link(var1, var2)...
         gatherFuncAndVarSyms(
-            linkClause->v, mlir::omp::DeclareTargetCaptureClause::link, result);
+            clause.v, mlir::omp::DeclareTargetCaptureClause::link, result);
       });
 }
 
@@ -843,7 +819,7 @@ bool ClauseProcessor::processMap(
     llvm::SmallVectorImpl<const Fortran::semantics::Symbol *> *mapSymbols)
     const {
   fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
-  return findRepeatableClause<ClauseTy::Map>(
+  return findRepeatableClause2<ClauseTy::Map>(
       [&](const ClauseTy::Map *mapClause,
           const Fortran::parser::CharBlock &source) {
         mlir::Location clauseLocation = converter.genLocation(source);
@@ -935,43 +911,41 @@ bool ClauseProcessor::processReduction(
     llvm::SmallVectorImpl<mlir::Attribute> &reductionDeclSymbols,
     llvm::SmallVectorImpl<const Fortran::semantics::Symbol *> *reductionSymbols)
     const {
-  return findRepeatableClause<ClauseTy::Reduction>(
-      [&](const ClauseTy::Reduction *reductionClause,
+  return findRepeatableClause<omp::clause::Reduction>(
+      [&](const omp::clause::Reduction &clause,
           const Fortran::parser::CharBlock &) {
         ReductionProcessor rp;
-        rp.addReductionDecl(currentLocation, converter, reductionClause->v,
-                            reductionVars, reductionDeclSymbols,
-                            reductionSymbols);
+        rp.addReductionDecl(currentLocation, converter, clause, reductionVars,
+                            reductionDeclSymbols, reductionSymbols);
       });
 }
 
 bool ClauseProcessor::processSectionsReduction(
     mlir::Location currentLocation) const {
-  return findRepeatableClause<ClauseTy::Reduction>(
-      [&](const ClauseTy::Reduction *, const Fortran::parser::CharBlock &) {
+  return findRepeatableClause<omp::clause::Reduction>(
+      [&](const omp::clause::Reduction &, const Fortran::parser::CharBlock &) {
         TODO(currentLocation, "OMPC_Reduction");
       });
 }
 
 bool ClauseProcessor::processTo(
     llvm::SmallVectorImpl<DeclareTargetCapturePair> &result) const {
-  return findRepeatableClause<ClauseTy::To>(
-      [&](const ClauseTy::To *toClause, const Fortran::parser::CharBlock &) {
+  return findRepeatableClause<omp::clause::To>(
+      [&](const omp::clause::To &clause, const Fortran::parser::CharBlock &) {
         // Case: declare target to(func, var1, var2)...
-        gatherFuncAndVarSyms(toClause->v,
+        gatherFuncAndVarSyms(clause.v,
                              mlir::omp::DeclareTargetCaptureClause::to, result);
       });
 }
 
 bool ClauseProcessor::processEnter(
     llvm::SmallVectorImpl<DeclareTargetCapturePair> &result) const {
-  return findRepeatableClause<ClauseTy::Enter>(
-      [&](const ClauseTy::Enter *enterClause,
+  return findRepeatableClause<omp::clause::Enter>(
+      [&](const omp::clause::Enter &clause,
           const Fortran::parser::CharBlock &) {
         // Case: declare target enter(func, var1, var2)...
-        gatherFuncAndVarSyms(enterClause->v,
-                             mlir::omp::DeclareTargetCaptureClause::enter,
-                             result);
+        gatherFuncAndVarSyms(
+            clause.v, mlir::omp::DeclareTargetCaptureClause::enter, result);
       });
 }
 
@@ -981,11 +955,11 @@ bool ClauseProcessor::processUseDeviceAddr(
     llvm::SmallVectorImpl<mlir::Location> &useDeviceLocs,
     llvm::SmallVectorImpl<const Fortran::semantics::Symbol *> &useDeviceSymbols)
     const {
-  return findRepeatableClause<ClauseTy::UseDeviceAddr>(
-      [&](const ClauseTy::UseDeviceAddr *devAddrClause,
+  return findRepeatableClause<omp::clause::UseDeviceAddr>(
+      [&](const omp::clause::UseDeviceAddr &clause,
           const Fortran::parser::CharBlock &) {
-        addUseDeviceClause(converter, devAddrClause->v, operands,
-                           useDeviceTypes, useDeviceLocs, useDeviceSymbols);
+        addUseDeviceClause(converter, clause.v, operands, useDeviceTypes,
+                           useDeviceLocs, useDeviceSymbols);
       });
 }
 
@@ -995,10 +969,10 @@ bool ClauseProcessor::processUseDevicePtr(
     llvm::SmallVectorImpl<mlir::Location> &useDeviceLocs,
     llvm::SmallVectorImpl<const Fortran::semantics::Symbol *> &useDeviceSymbols)
     const {
-  return findRepeatableClause<ClauseTy::UseDevicePtr>(
-      [&](const ClauseTy::UseDevicePtr *devPtrClause,
+  return findRepeatableClause<omp::clause::UseDevicePtr>(
+      [&](const omp::clause::UseDevicePtr &clause,
           const Fortran::parser::CharBlock &) {
-        addUseDeviceClause(converter, devPtrClause->v, operands, useDeviceTypes,
+        addUseDeviceClause(converter, clause.v, operands, useDeviceTypes,
                            useDeviceLocs, useDeviceSymbols);
       });
 }
diff --git a/flang/lib/Lower/OpenMP/ClauseProcessor.h b/flang/lib/Lower/OpenMP/ClauseProcessor.h
index c87fc30c88bb93..3f6adcce8ae877 100644
--- a/flang/lib/Lower/OpenMP/ClauseProcessor.h
+++ b/flang/lib/Lower/OpenMP/ClauseProcessor.h
@@ -105,9 +105,8 @@ class ClauseProcessor {
                      llvm::SmallVectorImpl<mlir::Value> &dependOperands) const;
   bool
   processEnter(llvm::SmallVectorImpl<DeclareTargetCapturePair> &result) const;
-  bool
-  processIf(Fortran::parser::OmpIfClause::DirectiveNameModifier directiveName,
-            mlir::Value &result) const;
+  bool processIf(omp::clause::If::DirectiveNameModifier directiveName,
+                 mlir::Value &result) const;
   bool
   processLink(llvm::SmallVectorImpl<DeclareTargetCapturePair> &result) const;
 
@@ -178,6 +177,10 @@ class ClauseProcessor {
   /// if at least one instance was found.
   template <typename T>
   bool findRepeatableClause(
+      std::function<void(const T &, const Fortran::parser::CharBlock &source)>
+          callbackFn) const;
+  template <typename T>
+  bool findRepeatableClause2(
       std::function<void(const T *, const Fortran::parser::CharBlock &source)>
           callbackFn) const;
 
@@ -195,7 +198,7 @@ template <typename T>
 bool ClauseProcessor::processMotionClauses(
     Fortran::lower::StatementContext &stmtCtx,
     llvm::SmallVectorImpl<mlir::Value> &mapOperands) {
-  return findRepeatableClause<T>(
+  return findRepeatableClause2<T>(
       [&](const T *motionClause, const Fortran::parser::CharBlock &source) {
         mlir::Location clauseLocation = converter.genLocation(source);
         fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
@@ -295,6 +298,24 @@ const T *ClauseProcessor::findUniqueClause(
 
 template <typename T>
 bool ClauseProcessor::findRepeatableClause(
+    std::function<void(const T &, const Fortran::parser::CharBlock &source)>
+        callbackFn) const {
+  bool found = false;
+  ClauseIterator nextIt, endIt = clauses.end();
+  for (ClauseIterator it = clauses.begin(); it != endIt; it = nextIt) {
+    nextIt = findClause<T>(it, endIt);
+
+    if (nextIt != endIt) {
+      callbackFn(std::get<T>(nextIt->u), nextIt->source);
+      found = true;
+      ++nextIt;
+    }
+  }
+  return found;
+}
+
+template <typename T>
+bool ClauseProcessor::findRepeatableClause2(
     std::function<void(const T *, const Fortran::parser::CharBlock &source)>
         callbackFn) const {
   bool found = false;
diff --git a/flang/lib/Lower/OpenMP/Clauses.cpp b/flang/lib/Lower/OpenMP/Clauses.cpp
index 0b90b705b9e406..a3aa3d4de3cdc9 100644
--- a/flang/lib/Lower/OpenMP/Clauses.cpp
+++ b/flang/lib/Lower/OpenMP/Clauses.cpp
@@ -205,12 +205,6 @@ namespace clause {
 #undef EMPTY_CLASS
 #undef WRAPPER_CLASS
 
-using DefinedOperator = tomp::clause::DefinedOperatorT<SymIdent, SymReference>;
-using ProcedureDesignator =
-    tomp::clause::ProcedureDesignatorT<SymIdent, SymReference>;
-using ReductionOperator =
-    tomp::clause::ReductionOperatorT<SymIdent, SymReference>;
-
 DefinedOperator makeDefOp(const parser::DefinedOperator &inp,
                           semantics::SemanticsContext &semaCtx) {
   return DefinedOperator{
diff --git a/flang/lib/Lower/OpenMP/Clauses.h b/flang/lib/Lower/OpenMP/Clauses.h
index a7e563f4b0f90b..c167e34637d500 100644
--- a/flang/lib/Lower/OpenMP/Clauses.h
+++ b/flang/lib/Lower/OpenMP/Clauses.h
@@ -106,6 +106,12 @@ getBaseObject(const Object &object,
               Fortran::semantics::SemanticsContext &semaCtx);
 
 namespace clause {
+using DefinedOperator = tomp::clause::DefinedOperatorT<SymIdent, SymReference>;
+using ProcedureDesignator =
+    tomp::clause::ProcedureDesignatorT<SymIdent, SymReference>;
+using ReductionOperator =
+    tomp::clause::ReductionOperatorT<SymIdent, SymReference>;
+
 #ifdef EMPTY_CLASS
 #undef EMPTY_CLASS
 #endif
diff --git a/flang/lib/Lower/OpenMP/OpenMP.cpp b/flang/lib/Lower/OpenMP/OpenMP.cpp
index 7953bf83cba0fe..7445c0f13526f7 100644
--- a/flang/lib/Lower/OpenMP/OpenMP.cpp
+++ b/flang/lib/Lower/OpenMP/OpenMP.cpp
@@ -572,8 +572,7 @@ genParallelOp(Fortran::lower::AbstractConverter &converter,
   llvm::SmallVector<const Fortran::semantics::Symbol *> reductionSymbols;
 
   ClauseProcessor cp(converter, semaCtx, clauseList);
-  cp.processIf(Fortran::parser::OmpIfClause::DirectiveNameModifier::Parallel,
-               ifClauseOperand);
+  cp.processIf(clause::If::DirectiveNameModifier::Parallel, ifClauseOperand);
   cp.processNumThreads(stmtCtx, numThreadsClauseOperand);
   cp.processProcBind(procBindKindAttr);
   cp.processDefault();
@@ -676,8 +675,7 @@ genTaskOp(Fortran::lower::AbstractConverter &converter,
       dependOperands;
 
   ClauseProcessor cp(converter, semaCtx, clauseList);
-  cp.processIf(Fortran::parser::OmpIfClause::DirectiveNameModifier::Task,
-               ifClauseOperand);
+  cp.processIf(clause::If::DirectiveNameModifier::Task, ifClauseOperand);
   cp.processAllocate(allocatorOperands, allocateOperands);
   cp.processDefault();
   cp.processFinal(stmtCtx, finalClauseOperand);
@@ -738,7 +736,7 @@ genDataOp(Fortran::lower::AbstractConverter &converter,
   llvm::SmallVector<const Fortran::semantics::Symbol *> useDeviceSymbols;
 
   ClauseProcessor cp(converter, semaCtx, clauseList);
-  cp.processIf(Fortran::parser::OmpIfClause::DirectiveNameModifier::TargetData,
+  cp.processIf(clause::If::DirectiveNameModifier::TargetData,
                ifClauseOperand);
   cp.processDevice(stmtCtx, deviceOperand);
   cp.processUseDevicePtr(devicePtrOperands, useDeviceTypes, useDeviceLocs,
@@ -770,19 +768,16 @@ genEnterExitUpdateDataOp(Fortran::lower::AbstractConverter &converter,
   llvm::SmallVector<mlir::Value> mapOperands, dependOperands;
   llvm::SmallVector<mlir::Attribute> dependTypeOperands;
 
-  Fortran::parser::OmpIfClause::DirectiveNameModifier directiveName;
+  clause::If::DirectiveNameModifier directiveName;
   llvm::omp::Directive directive;
   if constexpr (std::is_same_v<OpTy, mlir::omp::EnterDataOp>) {
-    directiveName =
-        Fortran::parser::OmpIfClause::DirectiveNameModifier::TargetEnterData;
+    directiveName = clause::If::DirectiveNameModifier::TargetEnterData;
     directive = llvm::omp::Directive::OMPD_target_enter_data;
   } else if constexpr (std::is_same_v<OpTy, mlir::omp::ExitDataOp>) {
-    directiveName =
-        Fortran::parser::OmpIfClause::DirectiveNameModifier::TargetExitData;
+    directiveName = clause::If::DirectiveNameModifier::TargetExitData;
     directive = llvm::omp::Directive::OMPD_target_exit_data;
   } else if constexpr (std::is_same_v<OpTy, mlir::omp::UpdateDataOp>) {
-    directiveName =
-        Fortran::parser::OmpIfClause::DirectiveNameModifier::TargetUpdate;
+    directiveName = clause::If::DirectiveNameModifier::TargetUpdate;
     directive = llvm::omp::Directive::OMPD_target_update;
   } else {
     return nullptr;
@@ -984,8 +979,7 @@ genTargetOp(Fortran::lower::AbstractConverter &converter,
   llvm::SmallVector<const Fortran::semantics::Symbol *> mapSymbols;
 
   ClauseProcessor cp(converter, semaCtx, clauseList);
-  cp.processIf(Fortran::parser::OmpIfClause::DirectiveNameModifier::Target,
-               ifClauseOperand);
+  cp.processIf(clause::If::DirectiveNameModifier::Target, ifClauseOperand);
   cp.processDevice(stmtCtx, deviceOperand);
   cp.processThreadLimit(stmtCtx, threadLimitOperand);
   cp.processDepend(dependTypeOperands, dependOperands);
@@ -1102,8 +1096,7 @@ genTeamsOp(Fortran::lower::AbstractConverter &converter,
   llvm::SmallVector<mlir::Attribute> reductionDeclSymbols;
 
   ClauseProcessor cp(converter, semaCtx, clauseList);
-  cp.processIf(Fortran::parser::OmpIfClause::DirectiveNameModifier::Teams,
-               ifClauseOperand);
+  cp.processIf(clause::If::DirectiveNameModifier::Teams, ifClauseOperand);
   cp.processAllocate(allocatorOperands, allocateOperands);
   cp.processDefault();
   cp.processNumTeams(stmtCtx, numTeamsClauseOperand);
@@ -1142,8 +1135,9 @@ static mlir::omp::DeclareTargetDeviceType getDeclareTargetInfo(
 
   if (const auto *objectList{
           Fortran::parser::Unwrap<Fortran::parser::OmpObjectList>(spec.u)}) {
+    ObjectList objects{makeList(*objectList, semaCtx)};
     // Case: declare target(func, var1, var2)
-    gatherFuncAndVarSyms(*objectList, mlir::omp::DeclareTargetCaptureClause::to,
+    gatherFuncAndVarSyms(objects, mlir::omp::DeclareTargetCaptureClause::to,
                          symbolAndClause);
   } else if (const auto *clauseList{
                  Fortran::parser::Unwrap<Fortran::parser::OmpClauseList>(
@@ -1257,7 +1251,7 @@ genOmpFlush(Fortran::lower::AbstractConverter &converter,
   if (const auto &ompObjectList =
           std::get<std::optional<Fortran::parser::OmpObjectList>>(
               flushConstruct.t))
-    genObjectList(*ompObjectList, converter, operandRange);
+    genObjectList2(*ompObjectList, converter, operandRange);
   const auto &memOrderClause =
       std::get<std::optional<std::list<Fortran::parser::OmpMemoryOrderClause>>>(
           flushConstruct.t);
@@ -1419,8 +1413,7 @@ createSimdLoop(Fortran::lower::AbstractConverter &converter,
                      loopVarTypeSize);
   cp.processScheduleChunk(stmtCtx, scheduleChunkClauseOperand);
   cp.processReduction(loc, reductionVars, reductionDeclSymbols);
-  cp.processIf(Fortran::parser::OmpIfClause::DirectiveNameModifier::Simd,
-               ifClauseOperand);
+  cp.processIf(clause::If::DirectiveNameModifier::Simd, ifClauseOperand);
   cp.processSimdlen(simdlenClauseOperand);
   cp.processSafelen(safelenClauseOperand);
   cp.processTODO<Fortran::parser::OmpClause::Aligned,
@@ -2223,106 +2216,99 @@ void Fortran::lower::genOpenMPReduction(
     const Fortran::parser::OmpClauseList &clauseList) {
   fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
 
-  for (const Fortran::parser::OmpClause &clause : clauseList.v) {
+  List<Clause> clauses{makeList(clauseList, semaCtx)};
+
+  for (const Clause &clause : clauses) {
     if (const auto &reductionClause =
-            std::get_if<Fortran::parser::OmpClause::Reduction>(&clause.u)) {
-      const auto &redOperator{std::get<Fortran::parser::OmpReductionOperator>(
-          reductionClause->v.t)};
-      const auto &objectList{
-          std::get<Fortran::parser::OmpObjectList>(reductionClause->v.t)};
+            std::get_if<clause::Reduction>(&clause.u)) {
+      const auto &redOperator{
+          std::get<clause::ReductionOperator>(reductionClause->t)};
+      const auto &objects{std::get<ObjectList>(reductionClause->t)};
       if (const auto *reductionOp =
-              std::get_if<Fortran::parser::DefinedOperator>(&redOperator.u)) {
+              std::get_if<clause::DefinedOperator>(&redOperator.u)) {
         const auto &intrinsicOp{
-            std::get<Fortran::parser::DefinedOperator::IntrinsicOperator>(
+            std::get<clause::DefinedOperator::IntrinsicOperator>(
                 reductionOp->u)};
 
         switch (intrinsicOp) {
-        case Fortran::parser::DefinedOperator::IntrinsicOperator::Add:
-        case Fortran::parser::DefinedOperator::IntrinsicOperator::Multiply:
-        case Fortran::parser::DefinedOperator::IntrinsicOperator::AND:
-        case Fortran::parser::DefinedOperator::IntrinsicOperator::EQV:
-        case Fortran::parser::DefinedOperator::IntrinsicOperator::OR:
-        case Fortran::parser::DefinedOperator::IntrinsicOperator::NEQV:
+        case clause::DefinedOperator::IntrinsicOperator::Add:
+        case clause::DefinedOperator::IntrinsicOperator::Multiply:
+        case clause::DefinedOperator::IntrinsicOperator::AND:
+        case clause::DefinedOperator::IntrinsicOperator::EQV:
+        case clause::DefinedOperator::IntrinsicOperator::OR:
+        case clause::DefinedOperator::IntrinsicOperator::NEQV:
           break;
         default:
           continue;
         }
-        for (const Fortran::parser::OmpObject &ompObject : objectList.v) {
-          if (const auto *name{
-                  Fortran::parser::Unwrap<Fortran::parser::Name>(ompObject)}) {
-            if (const Fortran::semantics::Symbol * symbol{name->symbol}) {
-              mlir::Value reductionVal = converter.getSymbolAddress(*symbol);
-              if (auto declOp = reductionVal.getDefiningOp<hlfir::DeclareOp>())
-                reductionVal = declOp.getBase();
-              mlir::Type reductionType =
-                  reductionVal.getType().cast<fir::ReferenceType>().getEleTy();
-              if (!reductionType.isa<fir::LogicalType>()) {
-                if (!reductionType.isIntOrIndexOrFloat())
-                  continue;
-              }
-              for (mlir::OpOperand &reductionValUse : reductionVal.getUses()) {
-                if (auto loadOp = mlir::dyn_cast<fir::LoadOp>(
-                        reductionValUse.getOwner())) {
-                  mlir::Value loadVal = loadOp.getRes();
-                  if (reductionType.isa<fir::LogicalType>()) {
-                    mlir::Operation *reductionOp = findReductionChain(loadVal);
-                    fir::ConvertOp convertOp =
-                        getConvertFromReductionOp(reductionOp, loadVal);
-                    updateReduction(reductionOp, firOpBuilder, loadVal,
-                                    reductionVal, &convertOp);
-                    removeStoreOp(reductionOp, reductionVal);
-                  } else if (mlir::Operation *reductionOp =
-                                 findReductionChain(loadVal, &reductionVal)) {
-                    updateReduction(reductionOp, firOpBuilder, loadVal,
-                                    reductionVal);
-                  }
+        for (const Object &object : objects) {
+          if (const Fortran::semantics::Symbol *symbol = object.id()) {
+            mlir::Value reductionVal = converter.getSymbolAddress(*symbol);
+            if (auto declOp = reductionVal.getDefiningOp<hlfir::DeclareOp>())
+              reductionVal = declOp.getBase();
+            mlir::Type reductionType =
+                reductionVal.getType().cast<fir::ReferenceType>().getEleTy();
+            if (!reductionType.isa<fir::LogicalType>()) {
+              if (!reductionType.isIntOrIndexOrFloat())
+                continue;
+            }
+            for (mlir::OpOperand &reductionValUse : reductionVal.getUses()) {
+              if (auto loadOp = mlir::dyn_cast<fir::LoadOp>(reductionValUse.getOwner())) {
+                mlir::Value loadVal = loadOp.getRes();
+                if (reductionType.isa<fir::LogicalType>()) {
+                  mlir::Operation *reductionOp = findReductionChain(loadVal);
+                  fir::ConvertOp convertOp =
+                      getConvertFromReductionOp(reductionOp, loadVal);
+                  updateReduction(reductionOp, firOpBuilder, loadVal,
+                                  reductionVal, &convertOp);
+                  removeStoreOp(reductionOp, reductionVal);
+                } else if (mlir::Operation *reductionOp =
+                               findReductionChain(loadVal, &reductionVal)) {
+                  updateReduction(reductionOp, firOpBuilder, loadVal,
+                                  reductionVal);
                 }
               }
             }
           }
         }
       } else if (const auto *reductionIntrinsic =
-                     std::get_if<Fortran::parser::ProcedureDesignator>(
+                     std::get_if<clause::ProcedureDesignator>(
                          &redOperator.u)) {
         if (!ReductionProcessor::supportedIntrinsicProcReduction(
                 *reductionIntrinsic))
           continue;
         ReductionProcessor::ReductionIdentifier redId =
             ReductionProcessor::getReductionType(*reductionIntrinsic);
-        for (const Fortran::parser::OmpObject &ompObject : objectList.v) {
-          if (const auto *name{
-                  Fortran::parser::Unwrap<Fortran::parser::Name>(ompObject)}) {
-            if (const Fortran::semantics::Symbol * symbol{name->symbol}) {
-              mlir::Value reductionVal = converter.getSymbolAddress(*symbol);
-              if (auto declOp = reductionVal.getDefiningOp<hlfir::DeclareOp>())
-                reductionVal = declOp.getBase();
-              for (const mlir::OpOperand &reductionValUse :
-                   reductionVal.getUses()) {
-                if (auto loadOp = mlir::dyn_cast<fir::LoadOp>(
-                        reductionValUse.getOwner())) {
-                  mlir::Value loadVal = loadOp.getRes();
-                  // Max is lowered as a compare -> select.
-                  // Match the pattern here.
-                  mlir::Operation *reductionOp =
-                      findReductionChain(loadVal, &reductionVal);
-                  if (reductionOp == nullptr)
-                    continue;
-
-                  if (redId == ReductionProcessor::ReductionIdentifier::MAX ||
-                      redId == ReductionProcessor::ReductionIdentifier::MIN) {
-                    assert(mlir::isa<mlir::arith::SelectOp>(reductionOp) &&
-                           "Selection Op not found in reduction intrinsic");
-                    mlir::Operation *compareOp =
-                        getCompareFromReductionOp(reductionOp, loadVal);
-                    updateReduction(compareOp, firOpBuilder, loadVal,
-                                    reductionVal);
-                  }
-                  if (redId == ReductionProcessor::ReductionIdentifier::IOR ||
-                      redId == ReductionProcessor::ReductionIdentifier::IEOR ||
-                      redId == ReductionProcessor::ReductionIdentifier::IAND) {
-                    updateReduction(reductionOp, firOpBuilder, loadVal,
-                                    reductionVal);
-                  }
+        for (const Object &object : objects) {
+          if (const Fortran::semantics::Symbol *symbol = object.id()) {
+            mlir::Value reductionVal = converter.getSymbolAddress(*symbol);
+            if (auto declOp = reductionVal.getDefiningOp<hlfir::DeclareOp>())
+              reductionVal = declOp.getBase();
+            for (const mlir::OpOperand &reductionValUse :
+                 reductionVal.getUses()) {
+              if (auto loadOp = mlir::dyn_cast<fir::LoadOp>(reductionValUse.getOwner())) {
+                mlir::Value loadVal = loadOp.getRes();
+                // Max is lowered as a compare -> select.
+                // Match the pattern here.
+                mlir::Operation *reductionOp =
+                    findReductionChain(loadVal, &reductionVal);
+                if (reductionOp == nullptr)
+                  continue;
+
+                if (redId == ReductionProcessor::ReductionIdentifier::MAX ||
+                    redId == ReductionProcessor::ReductionIdentifier::MIN) {
+                  assert(mlir::isa<mlir::arith::SelectOp>(reductionOp) &&
+                         "Selection Op not found in reduction intrinsic");
+                  mlir::Operation *compareOp =
+                      getCompareFromReductionOp(reductionOp, loadVal);
+                  updateReduction(compareOp, firOpBuilder, loadVal,
+                                  reductionVal);
+                }
+                if (redId == ReductionProcessor::ReductionIdentifier::IOR ||
+                    redId == ReductionProcessor::ReductionIdentifier::IEOR ||
+                    redId == ReductionProcessor::ReductionIdentifier::IAND) {
+                  updateReduction(reductionOp, firOpBuilder, loadVal,
+                                  reductionVal);
                 }
               }
             }
diff --git a/flang/lib/Lower/OpenMP/ReductionProcessor.cpp b/flang/lib/Lower/OpenMP/ReductionProcessor.cpp
index a8b98f3f567249..bf755b27487d95 100644
--- a/flang/lib/Lower/OpenMP/ReductionProcessor.cpp
+++ b/flang/lib/Lower/OpenMP/ReductionProcessor.cpp
@@ -23,9 +23,9 @@ namespace lower {
 namespace omp {
 
 ReductionProcessor::ReductionIdentifier ReductionProcessor::getReductionType(
-    const Fortran::parser::ProcedureDesignator &pd) {
+    const omp::clause::ProcedureDesignator &pd) {
   auto redType = llvm::StringSwitch<std::optional<ReductionIdentifier>>(
-                     ReductionProcessor::getRealName(pd).ToString())
+                     getRealName(pd.v.id()).ToString())
                      .Case("max", ReductionIdentifier::MAX)
                      .Case("min", ReductionIdentifier::MIN)
                      .Case("iand", ReductionIdentifier::IAND)
@@ -37,21 +37,21 @@ ReductionProcessor::ReductionIdentifier ReductionProcessor::getReductionType(
 }
 
 ReductionProcessor::ReductionIdentifier ReductionProcessor::getReductionType(
-    Fortran::parser::DefinedOperator::IntrinsicOperator intrinsicOp) {
+    omp::clause::DefinedOperator::IntrinsicOperator intrinsicOp) {
   switch (intrinsicOp) {
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::Add:
+  case omp::clause::DefinedOperator::IntrinsicOperator::Add:
     return ReductionIdentifier::ADD;
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::Subtract:
+  case omp::clause::DefinedOperator::IntrinsicOperator::Subtract:
     return ReductionIdentifier::SUBTRACT;
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::Multiply:
+  case omp::clause::DefinedOperator::IntrinsicOperator::Multiply:
     return ReductionIdentifier::MULTIPLY;
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::AND:
+  case omp::clause::DefinedOperator::IntrinsicOperator::AND:
     return ReductionIdentifier::AND;
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::EQV:
+  case omp::clause::DefinedOperator::IntrinsicOperator::EQV:
     return ReductionIdentifier::EQV;
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::OR:
+  case omp::clause::DefinedOperator::IntrinsicOperator::OR:
     return ReductionIdentifier::OR;
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::NEQV:
+  case omp::clause::DefinedOperator::IntrinsicOperator::NEQV:
     return ReductionIdentifier::NEQV;
   default:
     llvm_unreachable("unexpected intrinsic operator in reduction");
@@ -59,13 +59,11 @@ ReductionProcessor::ReductionIdentifier ReductionProcessor::getReductionType(
 }
 
 bool ReductionProcessor::supportedIntrinsicProcReduction(
-    const Fortran::parser::ProcedureDesignator &pd) {
-  const auto *name{Fortran::parser::Unwrap<Fortran::parser::Name>(pd)};
-  assert(name && "Invalid Reduction Intrinsic.");
-  if (!name->symbol->GetUltimate().attrs().test(
-          Fortran::semantics::Attr::INTRINSIC))
+    const omp::clause::ProcedureDesignator &pd) {
+  Fortran::semantics::Symbol *sym = pd.v.id();
+  if (!sym->GetUltimate().attrs().test(Fortran::semantics::Attr::INTRINSIC))
     return false;
-  auto redType = llvm::StringSwitch<bool>(getRealName(name).ToString())
+  auto redType = llvm::StringSwitch<bool>(getRealName(sym).ToString())
                      .Case("max", true)
                      .Case("min", true)
                      .Case("iand", true)
@@ -84,24 +82,24 @@ std::string ReductionProcessor::getReductionName(llvm::StringRef name,
 }
 
 std::string ReductionProcessor::getReductionName(
-    Fortran::parser::DefinedOperator::IntrinsicOperator intrinsicOp,
+    omp::clause::DefinedOperator::IntrinsicOperator intrinsicOp,
     mlir::Type ty) {
   std::string reductionName;
 
   switch (intrinsicOp) {
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::Add:
+  case omp::clause::DefinedOperator::IntrinsicOperator::Add:
     reductionName = "add_reduction";
     break;
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::Multiply:
+  case omp::clause::DefinedOperator::IntrinsicOperator::Multiply:
     reductionName = "multiply_reduction";
     break;
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::AND:
+  case omp::clause::DefinedOperator::IntrinsicOperator::AND:
     return "and_reduction";
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::EQV:
+  case omp::clause::DefinedOperator::IntrinsicOperator::EQV:
     return "eqv_reduction";
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::OR:
+  case omp::clause::DefinedOperator::IntrinsicOperator::OR:
     return "or_reduction";
-  case Fortran::parser::DefinedOperator::IntrinsicOperator::NEQV:
+  case omp::clause::DefinedOperator::IntrinsicOperator::NEQV:
     return "neqv_reduction";
   default:
     reductionName = "other_reduction";
@@ -305,7 +303,7 @@ mlir::omp::ReductionDeclareOp ReductionProcessor::createReductionDecl(
 void ReductionProcessor::addReductionDecl(
     mlir::Location currentLocation,
     Fortran::lower::AbstractConverter &converter,
-    const Fortran::parser::OmpReductionClause &reduction,
+    const omp::clause::Reduction &reduction,
     llvm::SmallVectorImpl<mlir::Value> &reductionVars,
     llvm::SmallVectorImpl<mlir::Attribute> &reductionDeclSymbols,
     llvm::SmallVectorImpl<const Fortran::semantics::Symbol *>
@@ -313,12 +311,12 @@ void ReductionProcessor::addReductionDecl(
   fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
   mlir::omp::ReductionDeclareOp decl;
   const auto &redOperator{
-      std::get<Fortran::parser::OmpReductionOperator>(reduction.t)};
-  const auto &objectList{std::get<Fortran::parser::OmpObjectList>(reduction.t)};
+      std::get<omp::clause::ReductionOperator>(reduction.t)};
+  const auto &objectList{std::get<omp::ObjectList>(reduction.t)};
   if (const auto &redDefinedOp =
-          std::get_if<Fortran::parser::DefinedOperator>(&redOperator.u)) {
+          std::get_if<omp::clause::DefinedOperator>(&redOperator.u)) {
     const auto &intrinsicOp{
-        std::get<Fortran::parser::DefinedOperator::IntrinsicOperator>(
+        std::get<omp::clause::DefinedOperator::IntrinsicOperator>(
             redDefinedOp->u)};
     ReductionIdentifier redId = getReductionType(intrinsicOp);
     switch (redId) {
@@ -334,10 +332,41 @@ void ReductionProcessor::addReductionDecl(
            "Reduction of some intrinsic operators is not supported");
       break;
     }
-    for (const Fortran::parser::OmpObject &ompObject : objectList.v) {
-      if (const auto *name{
-              Fortran::parser::Unwrap<Fortran::parser::Name>(ompObject)}) {
-        if (const Fortran::semantics::Symbol * symbol{name->symbol}) {
+    for (const omp::Object &object : objectList) {
+      if (const Fortran::semantics::Symbol *symbol = object.id()) {
+        if (reductionSymbols)
+          reductionSymbols->push_back(symbol);
+        mlir::Value symVal = converter.getSymbolAddress(*symbol);
+        if (auto declOp = symVal.getDefiningOp<hlfir::DeclareOp>())
+          symVal = declOp.getBase();
+        mlir::Type redType =
+            symVal.getType().cast<fir::ReferenceType>().getEleTy();
+        reductionVars.push_back(symVal);
+        if (redType.isa<fir::LogicalType>())
+          decl = createReductionDecl(
+              firOpBuilder,
+              getReductionName(intrinsicOp, firOpBuilder.getI1Type()), redId,
+              redType, currentLocation);
+        else if (redType.isIntOrIndexOrFloat()) {
+          decl = createReductionDecl(firOpBuilder,
+                                     getReductionName(intrinsicOp, redType),
+                                     redId, redType, currentLocation);
+        } else {
+          TODO(currentLocation, "Reduction of some types is not supported");
+        }
+        reductionDeclSymbols.push_back(mlir::SymbolRefAttr::get(
+            firOpBuilder.getContext(), decl.getSymName()));
+      }
+    }
+  } else if (const auto *reductionIntrinsic =
+                 std::get_if<omp::clause::ProcedureDesignator>(
+                     &redOperator.u)) {
+    if (ReductionProcessor::supportedIntrinsicProcReduction(
+            *reductionIntrinsic)) {
+      ReductionProcessor::ReductionIdentifier redId =
+          ReductionProcessor::getReductionType(*reductionIntrinsic);
+      for (const omp::Object &object : objectList) {
+        if (const Fortran::semantics::Symbol *symbol = object.id()) {
           if (reductionSymbols)
             reductionSymbols->push_back(symbol);
           mlir::Value symVal = converter.getSymbolAddress(*symbol);
@@ -346,68 +375,28 @@ void ReductionProcessor::addReductionDecl(
           mlir::Type redType =
               symVal.getType().cast<fir::ReferenceType>().getEleTy();
           reductionVars.push_back(symVal);
-          if (redType.isa<fir::LogicalType>())
-            decl = createReductionDecl(
-                firOpBuilder,
-                getReductionName(intrinsicOp, firOpBuilder.getI1Type()), redId,
-                redType, currentLocation);
-          else if (redType.isIntOrIndexOrFloat()) {
-            decl = createReductionDecl(firOpBuilder,
-                                       getReductionName(intrinsicOp, redType),
-                                       redId, redType, currentLocation);
-          } else {
-            TODO(currentLocation, "Reduction of some types is not supported");
-          }
+          assert(redType.isIntOrIndexOrFloat() && "Unsupported reduction type");
+          decl = createReductionDecl(
+              firOpBuilder,
+              getReductionName(getRealName(*reductionIntrinsic).ToString(),
+                               redType),
+              redId, redType, currentLocation);
           reductionDeclSymbols.push_back(mlir::SymbolRefAttr::get(
               firOpBuilder.getContext(), decl.getSymName()));
         }
       }
     }
-  } else if (const auto *reductionIntrinsic =
-                 std::get_if<Fortran::parser::ProcedureDesignator>(
-                     &redOperator.u)) {
-    if (ReductionProcessor::supportedIntrinsicProcReduction(
-            *reductionIntrinsic)) {
-      ReductionProcessor::ReductionIdentifier redId =
-          ReductionProcessor::getReductionType(*reductionIntrinsic);
-      for (const Fortran::parser::OmpObject &ompObject : objectList.v) {
-        if (const auto *name{
-                Fortran::parser::Unwrap<Fortran::parser::Name>(ompObject)}) {
-          if (const Fortran::semantics::Symbol * symbol{name->symbol}) {
-            if (reductionSymbols)
-              reductionSymbols->push_back(symbol);
-            mlir::Value symVal = converter.getSymbolAddress(*symbol);
-            if (auto declOp = symVal.getDefiningOp<hlfir::DeclareOp>())
-              symVal = declOp.getBase();
-            mlir::Type redType =
-                symVal.getType().cast<fir::ReferenceType>().getEleTy();
-            reductionVars.push_back(symVal);
-            assert(redType.isIntOrIndexOrFloat() &&
-                   "Unsupported reduction type");
-            decl = createReductionDecl(
-                firOpBuilder,
-                getReductionName(getRealName(*reductionIntrinsic).ToString(),
-                                 redType),
-                redId, redType, currentLocation);
-            reductionDeclSymbols.push_back(mlir::SymbolRefAttr::get(
-                firOpBuilder.getContext(), decl.getSymName()));
-          }
-        }
-      }
-    }
   }
 }
 
 const Fortran::semantics::SourceName
-ReductionProcessor::getRealName(const Fortran::parser::Name *name) {
-  return name->symbol->GetUltimate().name();
+ReductionProcessor::getRealName(const Fortran::semantics::Symbol *symbol) {
+  return symbol->GetUltimate().name();
 }
 
-const Fortran::semantics::SourceName ReductionProcessor::getRealName(
-    const Fortran::parser::ProcedureDesignator &pd) {
-  const auto *name{Fortran::parser::Unwrap<Fortran::parser::Name>(pd)};
-  assert(name && "Invalid Reduction Intrinsic.");
-  return getRealName(name);
+const Fortran::semantics::SourceName
+ReductionProcessor::getRealName(const omp::clause::ProcedureDesignator &pd) {
+  return getRealName(pd.v.id());
 }
 
 int ReductionProcessor::getOperationIdentity(ReductionIdentifier redId,
diff --git a/flang/lib/Lower/OpenMP/ReductionProcessor.h b/flang/lib/Lower/OpenMP/ReductionProcessor.h
index 00770fe81d1ef6..855e2aa4ad13cd 100644
--- a/flang/lib/Lower/OpenMP/ReductionProcessor.h
+++ b/flang/lib/Lower/OpenMP/ReductionProcessor.h
@@ -13,6 +13,7 @@
 #ifndef FORTRAN_LOWER_REDUCTIONPROCESSOR_H
 #define FORTRAN_LOWER_REDUCTIONPROCESSOR_H
 
+#include "Clauses.h"
 #include "flang/Optimizer/Builder/FIRBuilder.h"
 #include "flang/Parser/parse-tree.h"
 #include "flang/Semantics/symbol.h"
@@ -57,25 +58,25 @@ class ReductionProcessor {
   };
 
   static ReductionIdentifier
-  getReductionType(const Fortran::parser::ProcedureDesignator &pd);
+  getReductionType(const omp::clause::ProcedureDesignator &pd);
 
-  static ReductionIdentifier getReductionType(
-      Fortran::parser::DefinedOperator::IntrinsicOperator intrinsicOp);
+  static ReductionIdentifier
+  getReductionType(omp::clause::DefinedOperator::IntrinsicOperator intrinsicOp);
 
-  static bool supportedIntrinsicProcReduction(
-      const Fortran::parser::ProcedureDesignator &pd);
+  static bool
+  supportedIntrinsicProcReduction(const omp::clause::ProcedureDesignator &pd);
 
   static const Fortran::semantics::SourceName
-  getRealName(const Fortran::parser::Name *name);
+  getRealName(const Fortran::semantics::Symbol *symbol);
 
   static const Fortran::semantics::SourceName
-  getRealName(const Fortran::parser::ProcedureDesignator &pd);
+  getRealName(const omp::clause::ProcedureDesignator &pd);
 
   static std::string getReductionName(llvm::StringRef name, mlir::Type ty);
 
-  static std::string getReductionName(
-      Fortran::parser::DefinedOperator::IntrinsicOperator intrinsicOp,
-      mlir::Type ty);
+  static std::string
+  getReductionName(omp::clause::DefinedOperator::IntrinsicOperator intrinsicOp,
+                   mlir::Type ty);
 
   /// This function returns the identity value of the operator \p
   /// reductionOpName. For example:
@@ -112,7 +113,7 @@ class ReductionProcessor {
   static void
   addReductionDecl(mlir::Location currentLocation,
                    Fortran::lower::AbstractConverter &converter,
-                   const Fortran::parser::OmpReductionClause &reduction,
+                   const omp::clause::Reduction &reduction,
                    llvm::SmallVectorImpl<mlir::Value> &reductionVars,
                    llvm::SmallVectorImpl<mlir::Attribute> &reductionDeclSymbols,
                    llvm::SmallVectorImpl<const Fortran::semantics::Symbol *>
diff --git a/flang/lib/Lower/OpenMP/Utils.cpp b/flang/lib/Lower/OpenMP/Utils.cpp
index 31b15257d18687..9a6a28ded7006d 100644
--- a/flang/lib/Lower/OpenMP/Utils.cpp
+++ b/flang/lib/Lower/OpenMP/Utils.cpp
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "Utils.h"
+#include "Clauses.h"
 
 #include <flang/Lower/AbstractConverter.h>
 #include <flang/Lower/ConvertType.h>
@@ -28,9 +29,27 @@ namespace Fortran {
 namespace lower {
 namespace omp {
 
-void genObjectList(const Fortran::parser::OmpObjectList &objectList,
+void genObjectList(const ObjectList &objects,
                    Fortran::lower::AbstractConverter &converter,
                    llvm::SmallVectorImpl<mlir::Value> &operands) {
+  for (const Object &object : objects) {
+    const Fortran::semantics::Symbol *sym = object.id();
+    assert(sym && "Expected Symbol");
+    if (mlir::Value variable = converter.getSymbolAddress(*sym)) {
+      operands.push_back(variable);
+    } else {
+      if (const auto *details =
+              sym->detailsIf<Fortran::semantics::HostAssocDetails>()) {
+        operands.push_back(converter.getSymbolAddress(details->symbol()));
+        converter.copySymbolBinding(details->symbol(), *sym);
+      }
+    }
+  }
+}
+
+void genObjectList2(const Fortran::parser::OmpObjectList &objectList,
+                    Fortran::lower::AbstractConverter &converter,
+                    llvm::SmallVectorImpl<mlir::Value> &operands) {
   auto addOperands = [&](Fortran::lower::SymbolRef sym) {
     const mlir::Value variable = converter.getSymbolAddress(sym);
     if (variable) {
@@ -50,24 +69,10 @@ void genObjectList(const Fortran::parser::OmpObjectList &objectList,
 }
 
 void gatherFuncAndVarSyms(
-    const Fortran::parser::OmpObjectList &objList,
-    mlir::omp::DeclareTargetCaptureClause clause,
+    const ObjectList &objects, mlir::omp::DeclareTargetCaptureClause clause,
     llvm::SmallVectorImpl<DeclareTargetCapturePair> &symbolAndClause) {
-  for (const Fortran::parser::OmpObject &ompObject : objList.v) {
-    Fortran::common::visit(
-        Fortran::common::visitors{
-            [&](const Fortran::parser::Designator &designator) {
-              if (const Fortran::parser::Name *name =
-                      Fortran::semantics::getDesignatorNameIfDataRef(
-                          designator)) {
-                symbolAndClause.emplace_back(clause, *name->symbol);
-              }
-            },
-            [&](const Fortran::parser::Name &name) {
-              symbolAndClause.emplace_back(clause, *name.symbol);
-            }},
-        ompObject.u);
-  }
+  for (const Object &object : objects)
+    symbolAndClause.emplace_back(clause, *object.id());
 }
 
 Fortran::semantics::Symbol *
diff --git a/flang/lib/Lower/OpenMP/Utils.h b/flang/lib/Lower/OpenMP/Utils.h
index c346f891f0797e..4ab4bc9c137071 100644
--- a/flang/lib/Lower/OpenMP/Utils.h
+++ b/flang/lib/Lower/OpenMP/Utils.h
@@ -9,6 +9,7 @@
 #ifndef FORTRAN_LOWER_OPENMPUTILS_H
 #define FORTRAN_LOWER_OPENMPUTILS_H
 
+#include "Clauses.h"
 #include "mlir/Dialect/OpenMP/OpenMPDialect.h"
 #include "mlir/IR/Location.h"
 #include "mlir/IR/Value.h"
@@ -50,17 +51,20 @@ createMapInfoOp(fir::FirOpBuilder &builder, mlir::Location loc,
                 bool isVal = false);
 
 void gatherFuncAndVarSyms(
-    const Fortran::parser::OmpObjectList &objList,
-    mlir::omp::DeclareTargetCaptureClause clause,
+    const ObjectList &objects, mlir::omp::DeclareTargetCaptureClause clause,
     llvm::SmallVectorImpl<DeclareTargetCapturePair> &symbolAndClause);
 
 Fortran::semantics::Symbol *
 getOmpObjectSymbol(const Fortran::parser::OmpObject &ompObject);
 
-void genObjectList(const Fortran::parser::OmpObjectList &objectList,
+void genObjectList(const ObjectList &objects,
                    Fortran::lower::AbstractConverter &converter,
                    llvm::SmallVectorImpl<mlir::Value> &operands);
 
+void genObjectList2(const Fortran::parser::OmpObjectList &objectList,
+                    Fortran::lower::AbstractConverter &converter,
+                    llvm::SmallVectorImpl<mlir::Value> &operands);
+
 } // namespace omp
 } // namespace lower
 } // namespace Fortran



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