[flang][OpenMP] Parase bind clause for loop direcitve.

Adds parsing for the `bind` clause. The clause was already part of the
`loop` direcitve's definition but parsing was still missing.

Author: ergawy

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

@@ -551,6 +551,8 @@ class ParseTreeDumper {
   NODE_ENUM(OmpGrainsizeClause, Prescriptiveness)
   NODE(parser, OmpNumTasksClause)
   NODE_ENUM(OmpNumTasksClause, Prescriptiveness)
+  NODE(parser, OmpBindClause)
+  NODE_ENUM(OmpBindClause, Type)
   NODE(parser, OmpProcBindClause)
   NODE_ENUM(OmpProcBindClause, Type)
   NODE_ENUM(OmpReductionClause, ReductionModifier)

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

@@ -3702,6 +3702,13 @@ struct OmpNumTasksClause {
   std::tuple<std::optional<Prescriptiveness>, ScalarIntExpr> t;
 };
 
+// OMP 5.2 11.7.1 bind-clause ->
+//                  BIND( PARALLEL | TEAMS | THREAD )
+struct OmpBindClause {
+  ENUM_CLASS(Type, Parallel, Teams, Thread)
+  WRAPPER_CLASS_BOILERPLATE(OmpBindClause, Type);
+};
+
 // OpenMP Clauses
 struct OmpClause {
   UNION_CLASS_BOILERPLATE(OmpClause);

flang/lib/Parser/openmp-parsers.cpp

@@ -427,6 +427,12 @@ TYPE_PARSER(construct<OmpLastprivateClause>(
         pure(OmpLastprivateClause::LastprivateModifier::Conditional) / ":"),
     Parser<OmpObjectList>{}))
 
+// OMP 5.2 11.7.1 BIND ( PARALLEL | TEAMS | THREAD )
+TYPE_PARSER(construct<OmpBindClause>(
+    "PARALLEL" >> pure(OmpBindClause::Type::Parallel) ||
+    "TEAMS" >> pure(OmpBindClause::Type::Teams) ||
+    "THREAD" >> pure(OmpBindClause::Type::Thread)))
+
 TYPE_PARSER(
     "ACQUIRE" >> construct<OmpClause>(construct<OmpClause::Acquire>()) ||
     "ACQ_REL" >> construct<OmpClause>(construct<OmpClause::AcqRel>()) ||
@@ -441,6 +447,8 @@ TYPE_PARSER(
     "ATOMIC_DEFAULT_MEM_ORDER" >>
         construct<OmpClause>(construct<OmpClause::AtomicDefaultMemOrder>(
             parenthesized(Parser<OmpAtomicDefaultMemOrderClause>{}))) ||
+    "BIND" >> construct<OmpClause>(construct<OmpClause::Bind>(
+                  parenthesized(Parser<OmpBindClause>{}))) ||
     "COLLAPSE" >> construct<OmpClause>(construct<OmpClause::Collapse>(
                       parenthesized(scalarIntConstantExpr))) ||
     "COPYIN" >> construct<OmpClause>(construct<OmpClause::Copyin>(

flang/test/Parser/OpenMP/target-loop-unparse.f90

@@ -1,6 +1,8 @@
+! RUN: %flang_fc1 -fdebug-unparse -fopenmp -fopenmp-version=50 %s | \
+! RUN:   FileCheck --ignore-case %s
 
-! RUN: %flang_fc1 -fdebug-unparse -fopenmp %s | FileCheck --ignore-case %s
-! RUN: %flang_fc1 -fdebug-dump-parse-tree -fopenmp %s | FileCheck --check-prefix="PARSE-TREE" %s
+! RUN: %flang_fc1 -fdebug-dump-parse-tree -fopenmp -fopenmp-version=50 %s | \
+! RUN:   FileCheck --check-prefix="PARSE-TREE" %s
 
 ! Check for parsing of loop directive
 
@@ -14,6 +16,16 @@ subroutine test_loop
    j = j + 1
   end do
   !$omp end loop
+
+  !PARSE-TREE: OmpBeginLoopDirective
+  !PARSE-TREE-NEXT: OmpLoopDirective -> llvm::omp::Directive = loop
+  !PARSE-TREE-NEXT: OmpClauseList -> OmpClause -> Bind -> OmpBindClause -> Type = Thread
+  !CHECK: !$omp loop
+  !$omp loop bind(thread)
+  do i=1,10
+   j = j + 1
+  end do
+  !$omp end loop
 end subroutine
 
 subroutine test_target_loop

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

@@ -73,6 +73,7 @@ def OMPC_AtomicDefaultMemOrder : Clause<"atomic_default_mem_order"> {
 }
 def OMPC_Bind : Clause<"bind"> {
   let clangClass = "OMPBindClause";
+  let flangClass = "OmpBindClause";
 }
 def OMP_CANCELLATION_CONSTRUCT_Parallel : ClauseVal<"parallel", 1, 1> {}
 def OMP_CANCELLATION_CONSTRUCT_Loop : ClauseVal<"loop", 2, 1> {}