[Flang][OpenMP] Add Parsing support for Indirect Clause

As part of OpenMP Version 5.1, support for the `indirect` clause
was added for the `declare target` directive. This clause should
follow an `enter` clause, and allows procedure calls to be done
indirectly through OpenMP.

This adds Parsing support for the clause, along with semantics
checks. Currently, lowering for the clause is not supported so
a TODO message will be outputted to the user. It also performs
version checking as `indirect` is only support in OpenMP 5.1 or
greater.

See also: #110008

Author: Stylie777

flang/include/flang/Parser/dump-parse-tree.h

@@ -574,6 +574,7 @@ class ParseTreeDumper {
   NODE_ENUM(OmpDependenceType, Value)
   NODE(parser, OmpTaskDependenceType)
   NODE_ENUM(OmpTaskDependenceType, Value)
+  NODE(parser, OmpIndirectClause)
   NODE(parser, OmpIterationOffset)
   NODE(parser, OmpIteration)
   NODE(parser, OmpIterationVector)

flang/include/flang/Parser/parse-tree.h

@@ -4300,6 +4300,11 @@ struct OmpHoldsClause {
   WRAPPER_CLASS_BOILERPLATE(OmpHoldsClause, common::Indirection<Expr>);
 };
 
+// Ref: [5.2: 209]
+struct OmpIndirectClause {
+  WRAPPER_CLASS_BOILERPLATE(OmpIndirectClause, std::optional<ScalarLogicalExpr>);
+};
+
 // Ref: [5.2:72-73], in 4.5-5.1 it's scattered over individual directives
 // that allow the IF clause.
 //

flang/lib/Lower/OpenMP/Clauses.cpp

@@ -906,8 +906,8 @@ Inclusive make(const parser::OmpClause::Inclusive &inp,
 
 Indirect make(const parser::OmpClause::Indirect &inp,
               semantics::SemanticsContext &semaCtx) {
-  // inp -> empty
-  llvm_unreachable("Empty: indirect");
+  // inp.v.v -> std::optional<parser::ScalarLogicalExpr>
+  return Indirect{maybeApply(makeExprFn(semaCtx), inp.v.v)};
 }
 
 Init make(const parser::OmpClause::Init &inp,

flang/lib/Parser/openmp-parsers.cpp

@@ -996,6 +996,8 @@ TYPE_PARSER( //
     "IF" >> construct<OmpClause>(construct<OmpClause::If>(
                 parenthesized(Parser<OmpIfClause>{}))) ||
     "INBRANCH" >> construct<OmpClause>(construct<OmpClause::Inbranch>()) ||
+    "INDIRECT" >> construct<OmpClause>(construct<OmpClause::Indirect>(
+        maybe(parenthesized(scalarLogicalExpr)))) ||
     "INIT" >> construct<OmpClause>(construct<OmpClause::Init>(
                   parenthesized(Parser<OmpInitClause>{}))) ||
     "INCLUSIVE" >> construct<OmpClause>(construct<OmpClause::Inclusive>(

flang/lib/Semantics/check-omp-structure.cpp

@@ -1811,15 +1811,24 @@ void OmpStructureChecker::Leave(const parser::OmpDeclareTargetWithClause &x) {
     const parser::OmpClause *toClause = FindClause(llvm::omp::Clause::OMPC_to);
     const parser::OmpClause *linkClause =
         FindClause(llvm::omp::Clause::OMPC_link);
+    const parser::OmpClause *indirectClause = FindClause(llvm::omp::Clause::OMPC_indirect);
     if (!enterClause && !toClause && !linkClause) {
       context_.Say(x.source,
           "If the DECLARE TARGET directive has a clause, it must contain at least one ENTER clause or LINK clause"_err_en_US);
     }
+    if (indirectClause && !enterClause) {
+      context_.Say(x.source,
+          "The INDIRECT clause cannot be used without the ENTER clause with the DECLARE TARGET directive."_err_en_US);
+    }
     unsigned version{context_.langOptions().OpenMPVersion};
     if (toClause && version >= 52) {
       context_.Warn(common::UsageWarning::OpenMPUsage, toClause->source,
           "The usage of TO clause on DECLARE TARGET directive has been deprecated. Use ENTER clause instead."_warn_en_US);
     }
+    if(indirectClause && version < 51) {
+      context_.Say(x.source,
+        "The usage of INDIRECT clause on DECLARE TARGET directive is only supported on OpenMP Version 5.1 or greater"_err_en_US);
+    }
   }
 }
 

flang/lib/Semantics/check-omp-structure.h

@@ -243,6 +243,7 @@ class OmpStructureChecker
   void CheckSymbolNames(
       const parser::CharBlock &source, const parser::OmpObjectList &objList);
   void CheckIntentInPointer(SymbolSourceMap &, const llvm::omp::Clause);
+  void MakeScalarLogicalTrue(const parser::OmpClause *clause);
   void CheckProcedurePointer(SymbolSourceMap &, const llvm::omp::Clause);
   void CheckCrayPointee(const parser::OmpObjectList &objectList,
       llvm::StringRef clause, bool suggestToUseCrayPointer = true);

flang/test/Lower/OpenMP/Todo/omp-clause-indirect.f90

@@ -0,0 +1,34 @@
+! This test checks the lowering of OpenMP Indirect Clause when used with the Declare Target directive
+
+! RUN: not flang -fc1 -emit-fir -fopenmp -fopenmp-version=52 %s 2>&1 | FileCheck %s
+
+module functions
+  implicit none
+
+  interface
+    function func() result(i)
+      character(1) :: i
+    end function
+  end interface
+
+contains
+  function func1() result(i)
+    !CHECK: not yet implemented: Unhandled clause INDIRECT in DECLARE TARGET construct
+    !$omp declare target enter(func1) indirect(.true.)
+    character(1) :: i
+    i = 'a'
+    return
+  end function
+end module
+
+program main
+  use functions
+  implicit none
+  procedure (func), pointer :: ptr1=>func1
+  character(1) :: val1
+
+  !$omp target map(from: val1)
+  val1 = ptr1()
+  !$omp end target
+
+end program

flang/test/Parser/OpenMP/declare-target-indirect-tree.f90

@@ -0,0 +1,53 @@
+! REQUIRES: openmp_runtime
+
+! RUN: %flang_fc1 %openmp_flags -fopenmp-version=52 -fdebug-dump-parse-tree %s | FileCheck %s
+! RUN: %flang_fc1 %openmp_flags -fdebug-unparse -fopenmp-version=52 %s | FileCheck %s --check-prefix="UNPARSE"
+
+module functions
+  implicit none
+
+  interface
+  function func() result(i)
+    character(1) :: i
+  end function
+  end interface
+
+contains
+  function func1() result(i)
+    !$omp declare target enter(func1) indirect(.true.)
+    !CHECK: | | | | | OmpDeclareTargetSpecifier -> OmpDeclareTargetWithClause -> OmpClauseList -> OmpClause -> Enter -> OmpObjectList -> OmpObject -> Designator -> DataRef -> Name = 'func1'
+    !CHECK-NEXT: | | | | | OmpClause -> Indirect -> OmpIndirectClause -> Scalar -> Logical -> Expr = '.true._4'
+    !CHECK-NEXT: | | | | | | LiteralConstant -> LogicalLiteralConstant
+    !CHECK-NEXT: | | | | | | | bool = 'true'
+    character(1) :: i
+    i = 'a'
+    return
+  end function
+
+  function func2() result(i)
+    !$omp declare target enter(func2) indirect
+    !CHECK: | | | | | OmpDeclareTargetSpecifier -> OmpDeclareTargetWithClause -> OmpClauseList -> OmpClause -> Enter -> OmpObjectList -> OmpObject -> Designator -> DataRef -> Name = 'func2'
+    !CHECK-NEXT: | | | | | OmpClause -> Indirect -> OmpIndirectClause ->
+    character(1) :: i
+    i = 'b'
+    return
+  end function
+end module
+
+program main
+  use functions
+  implicit none
+  procedure (func), pointer :: ptr1=>func1, ptr2=>func2
+  character(1) :: val1, val2
+
+  !$omp target map(from: val1)
+  val1 = ptr1()
+  !$omp end target
+  !$omp target map(from: val2)
+  val2 = ptr2()
+  !$omp end target
+
+end program
+
+!UNPARSE: !$OMP DECLARE TARGET  ENTER(func1) INDIRECT(.true._4)
+!UNPARSE: !$OMP DECLARE TARGET  ENTER(func2) INDIRECT()

flang/test/Semantics/indirect01.f90

@@ -0,0 +1,34 @@
+! This test checks the lowering of OpenMP Indirect Clause when used with the Declare Target directive
+
+! RUN: not flang -fopenmp -fopenmp-version=52 %s 2>&1 | FileCheck %s
+
+module functions
+  implicit none
+
+  interface
+    function func() result(i)
+      character(1) :: i
+    end function
+  end interface
+
+contains
+  function func1() result(i)
+    !CHECK: The INDIRECT clause cannot be used without the ENTER clause with the DECLARE TARGET directive.
+    !$omp declare target indirect(.true.)
+    character(1) :: i
+    i = 'a'
+    return
+  end function
+end module
+
+program main
+  use functions
+  implicit none
+  procedure (func), pointer :: ptr1=>func1
+  character(1) :: val1
+
+  !$omp target map(from: val1)
+  val1 = ptr1()
+  !$omp end target
+
+end program

flang/test/Semantics/indirect02.f90

@@ -0,0 +1,36 @@
+! This test checks the lowering of OpenMP Indirect Clause when used with the Declare Target directive
+
+! RUN: not flang -fopenmp -fopenmp-version=50 %s 2>&1 | FileCheck %s --check-prefix="CHECK-50"
+! RUN: not flang -fopenmp -fopenmp-version=52 %s 2>&1 | FileCheck %s --check-prefix="CHECK-52"
+
+module functions
+  implicit none
+
+  interface
+    function func() result(i)
+      character(1) :: i
+    end function
+  end interface
+
+contains
+  function func1() result(i)
+    !CHECK-50: The usage of INDIRECT clause on DECLARE TARGET directive is only supported on OpenMP Version 5.1 or greater
+    !CHECK-52: not yet implemented: Unhandled clause INDIRECT in DECLARE TARGET construct
+    !$omp declare target enter(func1) indirect(.true.)
+    character(1) :: i
+    i = 'a'
+    return
+  end function
+end module
+
+program main
+  use functions
+  implicit none
+  procedure (func), pointer :: ptr1=>func1
+  character(1) :: val1
+
+  !$omp target map(from: val1)
+  val1 = ptr1()
+  !$omp end target
+
+end program

llvm/include/llvm/Frontend/OpenMP/ClauseT.h

@@ -701,7 +701,7 @@ template <typename T, typename I, typename E> //
 struct IndirectT {
   using InvokedByFptr = E;
   using WrapperTrait = std::true_type;
-  InvokedByFptr v;
+  OPT(InvokedByFptr) v;
 };
 
 // V5.2: [14.1.2] `init` clause

llvm/include/llvm/Frontend/OpenMP/OMP.td

@@ -244,6 +244,7 @@ def OMPC_Inclusive : Clause<"inclusive"> {
   let flangClass = "OmpObjectList";
 }
 def OMPC_Indirect : Clause<"indirect"> {
+  let flangClass = "OmpIndirectClause";
 }
 def OMPC_Init : Clause<"init"> {
   let clangClass = "OMPInitClause";