[Unity] Handle duplicate outputs in LazyTransformParams

python/tvm/relax/transform/lazy_transform_params.py

@@ -56,7 +56,9 @@ def visit_var_binding_(self, binding: relax.VarBinding) -> None:
         if binding.var == self.out_tuple_var:
             assert isinstance(binding.value, relax.Tuple)
             for i, expr in enumerate(binding.value.fields):
-                self.out_tuple_map[expr] = relax.PrimValue(i)
+                if expr not in self.out_tuple_map:
+                    self.out_tuple_map[expr] = []
+                self.out_tuple_map[expr].append(relax.PrimValue(i))
         else:
             self.is_tuple_get_item_input = False
             super().visit_var_binding_(binding)
@@ -198,17 +200,17 @@ def visit_var_binding_(self, binding: relax.VarBinding) -> None:
             for var in self.memory_free_insertion[binding.var]:
                 if var in self.out_tuple_map:
                     self.killed_vars.add(var)
-                    index = self.out_tuple_map[var]
-                    # rewrite set item
-                    self.builder_.emit(
-                        relax.Call(
-                            relax.ExternFunc("set_item"),
-                            [index, super().visit_var_(var)],
-                            None,
-                            [relax.ObjectStructInfo()],
-                        ),
-                        name_hint="_",
-                    )
+                    for index in self.out_tuple_map[var]:
+                        # rewrite set item
+                        self.builder_.emit(
+                            relax.Call(
+                                relax.ExternFunc("set_item"),
+                                [index, super().visit_var_(var)],
+                                None,
+                                [relax.ObjectStructInfo()],
+                            ),
+                            name_hint="_",
+                        )
 
                 if var in self.input_params_set:
                     self.builder_.emit(

tests/python/relax/test_transform_lazy_transform_params.py

@@ -376,5 +376,57 @@ def set_item(i, value):
         tvm.testing.assert_allclose(expected_i, transformed_i)
 
 
+def test_duplicate_outputs():
+    """A tensor may be repeated in the output
+
+    This is something that should be avoided upstream, but is a legal
+    parameter transformation, and should produce correct output.
+    """
+
+    @I.ir_module
+    class Before:
+        @R.function
+        def main_transform_params(
+            params: R.Tuple(R.Tensor([16], dtype="int32"), R.Tensor([16], dtype="int32"))
+        ):
+            R.func_attr({"relax.force_pure": True})
+            param0 = params[0]
+            param1 = params[1]
+            transformed0 = R.add(param0, R.const(1, "int32"))
+            transformed1 = R.add(param1, R.const(2, "int32"))
+            output = (transformed0, transformed1, transformed0)
+            return output
+
+    @I.ir_module
+    class Expected:
+        @R.function(pure=False)
+        def main_transform_params() -> R.Tuple:
+            gv: R.Object = R.call_packed("get_item", R.prim_value(0), sinfo_args=(R.Object,))
+            gv1: R.Tensor((16,), dtype="int32") = R.match_cast(gv, R.Tensor((16,), dtype="int32"))
+            param0: R.Tensor((16,), dtype="int32") = gv1
+
+            gv2: R.Object = R.call_packed("get_item", R.prim_value(1), sinfo_args=(R.Object,))
+            gv3: R.Tensor((16,), dtype="int32") = R.match_cast(gv2, R.Tensor((16,), dtype="int32"))
+            param1: R.Tensor((16,), dtype="int32") = gv3
+
+            transformed0: R.Tensor((16,), dtype="int32") = R.add(param0, R.const(1, "int32"))
+            _: R.Tuple = R.vm.kill_object(param0)
+            _: R.Object = R.call_packed(
+                "set_item", R.prim_value(0), transformed0, sinfo_args=(R.Object,)
+            )
+            _: R.Object = R.call_packed(
+                "set_item", R.prim_value(2), transformed0, sinfo_args=(R.Object,)
+            )
+
+            transformed1: R.Tensor((16,), dtype="int32") = R.add(param1, R.const(2, "int32"))
+            _ = R.vm.kill_object(param1)
+            _ = R.call_packed("set_item", R.prim_value(1), transformed1, sinfo_args=(R.Object,))
+            output = R.tuple()
+            return output
+
+    after = LazyTransformParams()(Before)
+    tvm.ir.assert_structural_equal(after, Expected)
+
+
 if __name__ == "__main__":
     tvm.testing.main()