[OpenMP] [Flang] [Semantics] Add a missing semantic check for OMP DISTRIBUTE directive.

[raghavendhra]

Summary

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.

[kiranchandramohan]

LG.
You will have to sync with @skatrak who is modifying the OmpDirectiveSets (https://reviews.llvm.org/D157493).

flang/lib/Semantics/resolve-directives.cpp

1869–1879

When we have one more of these, we can share code. No change requested.

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

static OmpDirectiveSet simdSet{Directive::OMPD_distribute_parallel_do_simd,
     Directive::OMPD_target_teams_distribute_simd, Directive::OMPD_taskloop_simd,
     Directive::OMPD_teams_distribute_parallel_do_simd,
     Directive::OMPD_teams_distribute_simd};
 static OmpDirectiveSet teamSet{Directive::OMPD_teams,
     Directive::OMPD_teams_distribute,
     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,
     Directive::OMPD_ordered, Directive::OMPD_atomic, Directive::OMPD_task,
     Directive::OMPD_taskloop};
 static OmpDirectiveSet nestedWorkshareErrSet{
     OmpDirectiveSet{Directive::OMPD_task, Directive::OMPD_taskloop,
         Directive::OMPD_critical, Directive::OMPD_ordered,

flang/lib/Semantics/resolve-directives.cpp

common::visit(
                         ((ompFlag == Symbol::Flag::OmpUseDeviceAddr) &&
                             symbol->test(Symbol::Flag::OmpUseDevicePtr)))) {
                   context_.Say(designator.source,
                       "Variable '%s' may not "
                       "appear on both USE_DEVICE_PTR and USE_DEVICE_ADDR "
                       "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
               if (AnalyzeExpr(context_, designator)) {
                 if (std::holds_alternative<parser::Substring>(designator.u)) {
                   context_.Say(designator.source,
                       "Substrings are not allowed on OpenMP "
                       "directives or clauses"_err_en_US);

flang/test/Semantics/OpenMP/firstprivate01.f90

 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.4 firstprivate Clause
 ! 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)
 
   a = 10
   b = 20
 
   !ERROR: TARGET construct with nested TEAMS region contains statements or directives outside of the TEAMS construct
program omp_firstprivate
   !$omp teams reduction(+:a)
   !ERROR: FIRSTPRIVATE variable 'a' is PRIVATE in outer context
   !$omp distribute firstprivate(a)
   do i = 1, 10
    b(i) = b(i) + a(i) + i
   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
 
   !$omp parallel private(a,b)
   !ERROR: FIRSTPRIVATE variable 'b' is PRIVATE in outer context
   !$omp do firstprivate(b)
   do i = 1, 10