[Flang][OpenMP] Restrict check to worksharing construct reductions

The outer context private check for reduction variables was firing for all constructs. This check is not applicable to non-worksharing constructs. OpenMP 5.2: Section 5.5.8 A list item that appears in a reduction clause on a worksharing construct must be shared in the parallel region to which a correspodning worksharing region binds. Reviewed By: peixin Differential Revision: https://reviews.llvm.org/D144824
llvm · Mar 9, 2023 · 460c2ea · 460c2ea
1 parent 99d053a
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Showing 3 changed files with 19 additions and 39 deletions.
diff --git a/flang/lib/Semantics/check-omp-structure.cpp b/flang/lib/Semantics/check-omp-structure.cpp
@@ -1981,7 +1981,13 @@ void OmpStructureChecker::CheckReductionTypeList(
   CheckIntentInPointerAndDefinable(
       ompObjectList, llvm::omp::Clause::OMPC_reduction);
   CheckReductionArraySection(ompObjectList);
-  CheckMultipleAppearanceAcrossContext(ompObjectList);
+  // If this is a worksharing construct then ensure the reduction variable
+  // is not private in the parallel region that it binds to.
+  OmpDirectiveSet workshareSet{llvm::omp::Directive::OMPD_do,
+      llvm::omp::Directive::OMPD_sections, llvm::omp::Directive::OMPD_do_simd};
+  if (workshareSet.test(GetContext().directive)) {
+    CheckSharedBindingInOuterContext(ompObjectList);
+  }
 }
 
 void OmpStructureChecker::CheckIntentInPointerAndDefinable(
@@ -2026,7 +2032,7 @@ void OmpStructureChecker::CheckReductionArraySection(
   }
 }
 
-void OmpStructureChecker::CheckMultipleAppearanceAcrossContext(
+void OmpStructureChecker::CheckSharedBindingInOuterContext(
     const parser::OmpObjectList &redObjectList) {
   //  TODO: Verify the assumption here that the immediately enclosing region is
   //  the parallel region to which the worksharing construct having reduction

diff --git a/flang/lib/Semantics/check-omp-structure.h b/flang/lib/Semantics/check-omp-structure.h
@@ -259,7 +259,7 @@ class OmpStructureChecker
       const parser::OmpObjectList &, const llvm::omp::Clause);
   void CheckArraySection(const parser::ArrayElement &arrayElement,
       const parser::Name &name, const llvm::omp::Clause clause);
-  void CheckMultipleAppearanceAcrossContext(
+  void CheckSharedBindingInOuterContext(
       const parser::OmpObjectList &ompObjectList);
   const parser::OmpObjectList *GetOmpObjectList(const parser::OmpClause &);
   void CheckPredefinedAllocatorRestriction(const parser::CharBlock &source,

diff --git a/flang/test/Semantics/OpenMP/reduction07.f90 b/flang/test/Semantics/OpenMP/reduction07.f90
@@ -78,50 +78,24 @@ program omp_reduction
 !$omp parallel reduction(*:a)
 !$omp end parallel
 
-
-!$omp parallel reduction(+:a)
-!ERROR: REDUCTION clause is not allowed on the WORKSHARE directive
-!ERROR: REDUCTION variable 'a' is REDUCTION in outer context must be shared in the parallel regions to which any of the worksharing regions arising from the worksharing construct bind.
-!$omp workshare reduction(*:a)
-a = a + 10
-!$omp end workshare
-!$omp end parallel
-
-!$omp parallel reduction(*:a)
-!$omp end parallel
-
-
-!$omp parallel reduction(+:a)
-!ERROR: REDUCTION clause is not allowed on the SINGLE directive
-!ERROR: REDUCTION variable 'a' is REDUCTION in outer context must be shared in the parallel regions to which any of the worksharing regions arising from the worksharing construct bind.
-!$omp single reduction(*:a)
-a = a + 10
-!$omp end single
-!$omp end parallel
-
-!$omp parallel reduction(+:a)
-!$omp end parallel
-
-
-!$omp parallel reduction(+:a)
-!ERROR: REDUCTION clause is not allowed on the SINGLE directive
-!ERROR: REDUCTION variable 'a' is REDUCTION in outer context must be shared in the parallel regions to which any of the worksharing regions arising from the worksharing construct bind.
-!$omp single reduction(iand:a)
-a = a + 10
-!$omp end single
-!$omp end parallel
-
-!$omp parallel reduction(iand:a)
-!$omp end parallel
-
 !$omp parallel reduction(ieor:a)
 !ERROR: REDUCTION variable 'a' is REDUCTION in outer context must be shared in the parallel regions to which any of the worksharing regions arising from the worksharing construct bind.
 !$omp sections reduction(+:a)
 a = ieor(a, 10)
 !$omp end sections
 !$omp end parallel
 
+!$omp parallel private(a)
 !$omp parallel reduction(ieor:a)
 !$omp end parallel
+!$omp end parallel
+
+!$omp task firstprivate(a)
+!$omp parallel do reduction(+:a)
+do i=1,10
+  a=a+j
+end do
+!$omp end parallel do
+!$omp end task
 
 end program omp_reduction