[flang][OpenMP] Add MLIR lowering for loop ... bind

Extends MLIR lowering support for the `loop` directive by adding
lowering support for the `bind` clause.

Author: ergawy

flang/lib/Lower/OpenMP/ClauseProcessor.cpp

@@ -98,6 +98,25 @@ genAllocateClause(lower::AbstractConverter &converter,
   genObjectList(objects, converter, allocateOperands);
 }
 
+static mlir::omp::ClauseBindKindAttr
+genBindKindAttr(fir::FirOpBuilder &firOpBuilder,
+                const omp::clause::Bind &clause) {
+  mlir::omp::ClauseBindKind bindKind;
+  switch (clause.v) {
+  case omp::clause::Bind::Binding::Teams:
+    bindKind = mlir::omp::ClauseBindKind::Teams;
+    break;
+  case omp::clause::Bind::Binding::Parallel:
+    bindKind = mlir::omp::ClauseBindKind::Parallel;
+    break;
+  case omp::clause::Bind::Binding::Thread:
+    bindKind = mlir::omp::ClauseBindKind::Thread;
+    break;
+  }
+  return mlir::omp::ClauseBindKindAttr::get(firOpBuilder.getContext(),
+                                            bindKind);
+}
+
 static mlir::omp::ClauseProcBindKindAttr
 genProcBindKindAttr(fir::FirOpBuilder &firOpBuilder,
                     const omp::clause::ProcBind &clause) {
@@ -199,6 +218,15 @@ static void convertLoopBounds(lower::AbstractConverter &converter,
 // ClauseProcessor unique clauses
 //===----------------------------------------------------------------------===//
 
+bool ClauseProcessor::processBind(mlir::omp::BindClauseOps &result) const {
+  if (auto *clause = findUniqueClause<omp::clause::Bind>()) {
+    fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
+    result.bindKind = genBindKindAttr(firOpBuilder, *clause);
+    return true;
+  }
+  return false;
+}
+
 bool ClauseProcessor::processCollapse(
     mlir::Location currentLocation, lower::pft::Evaluation &eval,
     mlir::omp::LoopRelatedClauseOps &result,

flang/lib/Lower/OpenMP/ClauseProcessor.h

@@ -53,6 +53,7 @@ class ClauseProcessor {
       : converter(converter), semaCtx(semaCtx), clauses(clauses) {}
 
   // 'Unique' clauses: They can appear at most once in the clause list.
+  bool processBind(mlir::omp::BindClauseOps &result) const;
   bool
   processCollapse(mlir::Location currentLocation, lower::pft::Evaluation &eval,
                   mlir::omp::LoopRelatedClauseOps &result,

flang/lib/Lower/OpenMP/Clauses.cpp

@@ -482,8 +482,19 @@ AtomicDefaultMemOrder make(const parser::OmpClause::AtomicDefaultMemOrder &inp,
 
 Bind make(const parser::OmpClause::Bind &inp,
           semantics::SemanticsContext &semaCtx) {
-  // inp -> empty
-  llvm_unreachable("Empty: bind");
+  // inp.v -> parser::OmpBindClause
+  using wrapped = parser::OmpBindClause;
+
+  CLAUSET_ENUM_CONVERT( //
+      convert, wrapped::Type, Bind::Binding,
+      // clang-format off
+      MS(Teams, Teams)
+      MS(Parallel, Parallel)
+      MS(Thread, Thread)
+      // clang-format on
+  );
+
+  return Bind{/*Binding=*/convert(inp.v.v)};
 }
 
 // CancellationConstructType: empty

flang/lib/Lower/OpenMP/OpenMP.cpp

@@ -2057,10 +2057,10 @@ static void genLoopClauses(
     mlir::omp::LoopOperands &clauseOps,
     llvm::SmallVectorImpl<const semantics::Symbol *> &reductionSyms) {
   ClauseProcessor cp(converter, semaCtx, clauses);
+  cp.processBind(clauseOps);
   cp.processOrder(clauseOps);
   cp.processReduction(loc, clauseOps, reductionSyms);
-  cp.processTODO<clause::Bind, clause::Lastprivate>(
-      loc, llvm::omp::Directive::OMPD_loop);
+  cp.processTODO<clause::Lastprivate>(loc, llvm::omp::Directive::OMPD_loop);
 }
 
 static void genLoopOp(lower::AbstractConverter &converter,

flang/test/Lower/OpenMP/loop-directive.f90

@@ -80,3 +80,15 @@ subroutine test_reduction()
   end do
   !$omp end loop
 end subroutine
+
+! CHECK-LABEL: func.func @_QPtest_bind
+subroutine test_bind()
+  integer :: i, dummy = 1
+  ! CHECK: omp.loop bind(thread) private(@{{.*}} %{{.*}}#0 -> %{{.*}} : {{.*}}) {
+  ! CHECK: }
+  !$omp loop bind(thread)
+  do i=1,10
+   dummy = dummy + 1
+  end do
+  !$omp end loop
+end subroutine