[Flang][OpenMP]Make Do concurrent indices private

[harishch4]

Fixes: #85538

[llvmbot]

@llvm/pr-subscribers-flang-semantics

@llvm/pr-subscribers-flang-openmp

Author: None (harishch4)

Changes

Fixes: #85538

---

Full diff: https://github.com/llvm/llvm-project/pull/93785.diff

2 Files Affected:

• (modified) flang/lib/Semantics/resolve-directives.cpp (+22-3)
• (added) flang/test/Semantics/OpenMP/doconcurrent01.f90 (+17)

diff --git a/flang/lib/Semantics/resolve-directives.cpp b/flang/lib/Semantics/resolve-directives.cpp
index dbc531372c3f4..3992d527c7ae5 100644
--- a/flang/lib/Semantics/resolve-directives.cpp
+++ b/flang/lib/Semantics/resolve-directives.cpp
@@ -1698,10 +1698,10 @@ void OmpAttributeVisitor::ResolveSeqLoopIndexInParallelOrTaskConstruct(
 // Use of DO CONCURRENT inside OpenMP construct is unspecified behavior
 // till OpenMP-5.0 standard.
 // In above both cases we skip the privatization of iteration variables.
+// [OpenMP 5.1] DO CONCURRENT indices are private
 bool OmpAttributeVisitor::Pre(const parser::DoConstruct &x) {
-  // TODO:[OpenMP 5.1] DO CONCURRENT indices are private
-  if (x.IsDoNormal()) {
-    if (!dirContext_.empty() && GetContext().withinConstruct) {
+  if (!dirContext_.empty() && GetContext().withinConstruct) {
+    if (x.IsDoNormal()) {
       const parser::Name *iv{GetLoopIndex(x)};
       if (iv && iv->symbol) {
         if (!iv->symbol->test(Symbol::Flag::OmpPreDetermined)) {
@@ -1721,6 +1721,25 @@ bool OmpAttributeVisitor::Pre(const parser::DoConstruct &x) {
           }
         }
       }
+    } else if (x.IsDoConcurrent()) {
+      const Fortran::parser::LoopControl *loopControl = &*x.GetLoopControl();
+      const Fortran::parser::LoopControl::Concurrent &concurrent =
+          std::get<Fortran::parser::LoopControl::Concurrent>(loopControl->u);
+      const Fortran::parser::ConcurrentHeader &concurrentHeader =
+          std::get<Fortran::parser::ConcurrentHeader>(concurrent.t);
+      const std::list<Fortran::parser::ConcurrentControl> &controls =
+          std::get<std::list<Fortran::parser::ConcurrentControl>>(
+              concurrentHeader.t);
+      for (const auto &control : controls) {
+        const parser::Name *iv{&std::get<0>(control.t)};
+        if (iv && iv->symbol) {
+          if (!iv->symbol->test(Symbol::Flag::OmpPreDetermined)) {
+            ResolveSeqLoopIndexInParallelOrTaskConstruct(*iv);
+          } else {
+            // TODO: conflict checks with explicitly determined DSA
+          }
+        }
+      }
     }
   }
   return true;
diff --git a/flang/test/Semantics/OpenMP/doconcurrent01.f90 b/flang/test/Semantics/OpenMP/doconcurrent01.f90
new file mode 100644
index 0000000000000..7e3bdce871dd4
--- /dev/null
+++ b/flang/test/Semantics/OpenMP/doconcurrent01.f90
@@ -0,0 +1,17 @@
+! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
+
+! OpenMP 5.1.1
+! DO Concurrent indices are private
+
+!DEF: /private_iv (Subroutine)Subprogram
+subroutine private_iv
+   !DEF: /private_iv/i ObjectEntity INTEGER(4)
+   integer i
+   !$omp parallel default(private)
+   !$omp single
+   !DEF: /private_iv/OtherConstruct1/i (OmpPrivate, OmpPreDetermined) HostAssoc INTEGER(4)
+   do concurrent(i=1:2)
+   end do
+   !$omp end single
+   !$omp end parallel
+end subroutine

[kiranchandramohan]

Is the threadprivate check not applicable here?

[harishch4]

The loop iteration variable may not appear in a threadprivatedirective. Yeah, sorry I missed it. If it's okay, I'll store symbols in a list and move common code out.

[kiranchandramohan]

Ok

[harishch4]

Due to a new symbol being declared here, the check won't work for DoConcurrent. I'll create an issue to try to handle it in a separate patch.

[kiranchandramohan]

LG.