[OpenMP] [Flang] [Semantics] Add a missing semantic check for OMP DIS…

…TRIBUTE directive.

Added semantic support for following restriction which applies to OMP DISTRIBUTE directives

  - A list item may appear in a firstprivate or lastprivate clause but not both.

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D157465

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

@@ -82,6 +82,17 @@ static OmpDirectiveSet teamSet{Directive::OMPD_teams,
     Directive::OMPD_teams_distribute_parallel_do,
     Directive::OMPD_teams_distribute_parallel_do_simd,
     Directive::OMPD_teams_distribute_simd};
+static OmpDirectiveSet distributeSet{Directive::OMPD_distribute,
+    Directive::OMPD_distribute_parallel_do,
+    Directive::OMPD_distribute_parallel_do_simd,
+    Directive::OMPD_distribute_simd, Directive::OMPD_target_teams_distribute,
+    Directive::OMPD_target_teams_distribute_parallel_do,
+    Directive::OMPD_target_teams_distribute_parallel_do_simd,
+    Directive::OMPD_target_teams_distribute_simd,
+    Directive::OMPD_teams_distribute,
+    Directive::OMPD_teams_distribute_parallel_do,
+    Directive::OMPD_teams_distribute_parallel_do_simd,
+    Directive::OMPD_teams_distribute_simd};
 static OmpDirectiveSet taskGeneratingSet{
     OmpDirectiveSet{Directive::OMPD_task} | taskloopSet};
 static OmpDirectiveSet nestedOrderedErrSet{Directive::OMPD_critical,

flang/lib/Semantics/resolve-directives.cpp

@@ -1866,6 +1866,17 @@ void OmpAttributeVisitor::ResolveOmpObject(
                       "clauses on a TARGET DATA construct"_err_en_US,
                       symbol->name());
                 }
+                if (llvm::omp::distributeSet.test(GetContext().directive) &&
+                    (((ompFlag == Symbol::Flag::OmpFirstPrivate) &&
+                         symbol->test(Symbol::Flag::OmpLastPrivate)) ||
+                        ((ompFlag == Symbol::Flag::OmpLastPrivate) &&
+                            symbol->test(Symbol::Flag::OmpFirstPrivate)))) {
+                  context_.Say(designator.source,
+                      "Variable '%s' may not "
+                      "appear on both FIRSTPRIVATE and LASTPRIVATE "
+                      "clauses on a DISTRIBUTE construct"_err_en_US,
+                      symbol->name());
+                }
               }
             } else {
               // Array sections to be changed to substrings as needed

flang/test/Semantics/OpenMP/firstprivate01.f90

@@ -4,6 +4,9 @@
 ! Variables that appear in a firstprivate clause on a distribute or
 ! worksharing constructs must not appear in the private or
 ! reduction clause in a teams or parallel constructs in the outer context
+!
+! A list item may appear in a firstprivate or lastprivate clause but not both on
+! a distribute directive
 
 program omp_firstprivate
   integer :: i, a(10), b(10), c(10)
@@ -29,6 +32,38 @@ program omp_firstprivate
   end do
   !$omp end distribute
   !$omp end teams
+
+  !$omp teams distribute firstprivate(a) lastprivate(b)
+  do i = 1, 10
+    a(i) = a(i) + b(i) - i
+  end do
+  !$omp end teams distribute
+  !ERROR: Variable 'b' may not appear on both FIRSTPRIVATE and LASTPRIVATE clauses on a DISTRIBUTE construct
+  !$omp teams distribute firstprivate(a,b) lastprivate(b)
+  do i = 1, 10
+    a(i) = a(i) + b(i) - i
+  end do
+  !$omp end teams distribute
+  !ERROR: Variable 'a' may not appear on both FIRSTPRIVATE and LASTPRIVATE clauses on a DISTRIBUTE construct
+  !ERROR: Variable 'b' may not appear on both FIRSTPRIVATE and LASTPRIVATE clauses on a DISTRIBUTE construct
+  !$omp teams distribute firstprivate(a,b) lastprivate(a,b)
+  do i = 1, 10
+    a(i) = a(i) + b(i) - i
+  end do
+  !$omp end teams distribute
+  !ERROR: Variable 'b' may not appear on both FIRSTPRIVATE and LASTPRIVATE clauses on a DISTRIBUTE construct
+  !$omp teams distribute lastprivate(a,b) firstprivate(b)
+  do i = 1, 10
+    a(i) = a(i) + b(i) - i
+  end do
+  !$omp end teams distribute
+  !ERROR: Variable 'b' may not appear on both FIRSTPRIVATE and LASTPRIVATE clauses on a DISTRIBUTE construct
+  !ERROR: Variable 'a' may not appear on both FIRSTPRIVATE and LASTPRIVATE clauses on a DISTRIBUTE construct
+  !$omp teams distribute lastprivate(a,b) firstprivate(b,a)
+  do i = 1, 10
+    a(i) = a(i) + b(i) - i
+  end do
+  !$omp end teams distribute
   !$omp end target
 
   print *, a, b