[flang-commits] [flang] 460c2ea - [Flang][OpenMP] Restrict check to worksharing construct reductions

[Kiran Chandramohan via flang-commits]

Author: Kiran Chandramohan
Date: 2023-03-09T14:13:04Z
New Revision: 460c2eaa4ad5dd2b19339d65affa25b00782dcb0

URL: https://github.com/llvm/llvm-project/commit/460c2eaa4ad5dd2b19339d65affa25b00782dcb0
DIFF: https://github.com/llvm/llvm-project/commit/460c2eaa4ad5dd2b19339d65affa25b00782dcb0.diff

LOG: [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

Added: 
    

Modified: 
    flang/lib/Semantics/check-omp-structure.cpp
    flang/lib/Semantics/check-omp-structure.h
    flang/test/Semantics/OpenMP/reduction07.f90

Removed: 
    


################################################################################
diff  --git a/flang/lib/Semantics/check-omp-structure.cpp b/flang/lib/Semantics/check-omp-structure.cpp
index b30ea418b1e7..cffdabf8441d 100644
--- 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
index 2751cdd6fbe9..992531a586db 100644
--- 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
index a3b58765d9a6..98ed69a8d846 100644
--- a/flang/test/Semantics/OpenMP/reduction07.f90
+++ b/flang/test/Semantics/OpenMP/reduction07.f90
@@ -78,42 +78,6 @@ 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)
@@ -121,7 +85,17 @@ program omp_reduction
 !$omp end sections
 !$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