[BYOC][bugfix] Handle empty tuples in annotation pass (apache#7288)

src/relay/transforms/annotate_target.cc

@@ -144,11 +144,12 @@ class AnnotateTargetRewriter : public ExprRewriter {
      */
     Expr new_expr = expr;
     const CallNode* call = expr.as<CallNode>();
+    const TupleNode* tup = expr.as<TupleNode>();
     if (op_expr_to_target_.find(expr) != op_expr_to_target_.end()) {
       // Check whether expr has args, if not - do not insert compiler_end.
       if (expr->IsInstance<RefWriteNode>() || expr->IsInstance<RefCreateNode>() ||
-          expr->IsInstance<RefReadNode>() || expr->IsInstance<TupleNode>() ||
-          expr->IsInstance<TupleGetItemNode>() || (call && !call->args.empty())) {
+          expr->IsInstance<RefReadNode>() || expr->IsInstance<TupleGetItemNode>() ||
+          (call && !call->args.empty()) || (tup && !tup->fields.empty())) {
         std::string target = op_expr_to_target_[new_expr];
         new_expr = InsertAnnotation(new_expr, target, make_end_op);
         op_expr_to_target_[new_expr] = target;

tests/python/relay/test_pass_annotate_target.py

@@ -738,8 +738,8 @@ def after():
         mod = tvm.IRModule.from_expr(func)
         return mod
 
-    for annotate_non_call_ops in [True, False, True]:
-        result = transform.AnnotateTarget(target)(before())
+    for annotate_non_call_ops in [True, False]:
+        result = transform.AnnotateTarget(target, annotate_non_call_ops)(before())
         expected = transform.InferType()(after())
         assert tvm.ir.structural_equal(expected, result)
 
@@ -764,6 +764,27 @@ def after():
     assert tvm.ir.structural_equal(expected, result)
 
 
+def test_empty_tuple():
+    target = "test_empty_tuple"
+
+    """An empty tuple should behave just like a call with no args (see above test)."""
+
+    def before():
+        func = relay.Function([], relay.Tuple([]))
+        mod = tvm.IRModule.from_expr(func)
+        return mod
+
+    def after():
+        func = relay.Function([], relay.Tuple([]))
+        mod = tvm.IRModule.from_expr(func)
+        return mod
+
+    for annotate_non_call_ops in [True, False]:
+        result = transform.AnnotateTarget(target, annotate_non_call_ops)(before())
+        expected = transform.InferType()(after())
+        assert tvm.ir.structural_equal(expected, result)
+
+
 if __name__ == "__main__":
     test_extern_dnnl()
     test_composite_function()
@@ -780,3 +801,4 @@ def after():
     test_double_target()
     test_ends_with_tuple()
     test_ref_create_read_write()
+    test_empty_tuple()