Add test for cfg workshare bufferization

Author: ivanradanov

flang/test/Transforms/OpenMP/should-use-workshare-lowering-cfg.mlir

@@ -0,0 +1,22 @@
+// RUN: fir-opt --bufferize-hlfir %s 2>&1 | FileCheck %s
+
+// CHECK: warning: omp workshare with unstructured control flow currently unsupported.
+func.func @warn_cfg(%arg: !fir.ref<!fir.array<42xi32>>, %idx : index) {
+  omp.workshare {
+  ^bb1:
+    %c42 = arith.constant 42 : index
+    %c1_i32 = arith.constant 1 : i32
+    %shape = fir.shape %c42 : (index) -> !fir.shape<1>
+    %array:2 = hlfir.declare %arg(%shape) {uniq_name = "array"} : (!fir.ref<!fir.array<42xi32>>, !fir.shape<1>) -> (!fir.ref<!fir.array<42xi32>>, !fir.ref<!fir.array<42xi32>>)
+    %elemental = hlfir.elemental %shape unordered : (!fir.shape<1>) -> !hlfir.expr<42xi32> {
+    ^bb0(%i: index):
+      hlfir.yield_element %c1_i32 : i32
+    }
+    hlfir.assign %elemental to %array#0 : !hlfir.expr<42xi32>, !fir.ref<!fir.array<42xi32>>
+    hlfir.destroy %elemental : !hlfir.expr<42xi32>
+    cf.br ^bb2
+  ^bb2:
+    omp.terminator
+  }
+  return
+}