[flang-commits] [flang] [Flang][OpenMP] Add Semantic Checks for Atomic Capture Construct (PR #108516)

[Kiran Chandramohan via flang-commits]

================
@@ -1977,6 +1977,64 @@ void OmpStructureChecker::CheckAtomicUpdateStmt(
   ErrIfAllocatableVariable(var);
 }
 
+// TODO: Allow cond-update-stmt once compare clause is supported.
+void OmpStructureChecker::CheckAtomicCaptureConstruct(
+    const parser::OmpAtomicCapture &atomicCaptureConstruct) {
+  const Fortran::parser::AssignmentStmt &stmt1 =
+      std::get<Fortran::parser::OmpAtomicCapture::Stmt1>(
+          atomicCaptureConstruct.t)
+          .v.statement;
+  const auto &stmt1Var{std::get<Fortran::parser::Variable>(stmt1.t)};
+  const auto &stmt1Expr{std::get<Fortran::parser::Expr>(stmt1.t)};
+
+  const Fortran::parser::AssignmentStmt &stmt2 =
+      std::get<Fortran::parser::OmpAtomicCapture::Stmt2>(
+          atomicCaptureConstruct.t)
+          .v.statement;
+  const auto &stmt2Var{std::get<Fortran::parser::Variable>(stmt2.t)};
+  const auto &stmt2Expr{std::get<Fortran::parser::Expr>(stmt2.t)};
+
+  if (Fortran::semantics::checkForSingleVariableOnRHS(stmt1)) {
+    CheckAtomicCaptureStmt(stmt1);
+    if (Fortran::semantics::checkForSymbolMatch(stmt2)) {
+      // Atomic capture construct is of the form [capture-stmt, update-stmt]
+      CheckAtomicUpdateStmt(stmt2);
+    } else {
+      // Atomic capture construct is of the form [capture-stmt, write-stmt]
+      CheckAtomicWriteStmt(stmt2);
+    }
+    auto *v{stmt2Var.typedExpr.get()};
+    auto *e{stmt1Expr.typedExpr.get()};
+    if (v && e && !(v->v == e->v)) {
+      context_.Say(stmt1Expr.source,
+          "Captured variable %s "
+          "expected to be assigned in the second statement of "
+          "atomic capture construct"_err_en_US,
----------------
kiranchandramohan wrote:

```suggestion
          "ATOMIC CAPTURE construct"_err_en_US,
```

https://github.com/llvm/llvm-project/pull/108516