fix(mge): ensure contiguous when passing tensor from graph rt to imperative rt

GitOrigin-RevId: e4d944343d051d9263498c200f17d951af67e9b5

imperative/python/test/unit/test_tracing.py

@@ -406,3 +406,16 @@ def test_clip():
 
     for i in range(3):
         f(x, tensor([0]), tensor([1]))
+
+
+# test returning noncontiguous tensor from trace
+def test_slice():
+    @trace
+    def f(x):
+        return x[:, 1::2]
+
+    x = F.arange(8).reshape(2, 4)
+    f(x)
+    y = f(x)
+    np.testing.assert_array_equal(y.numpy(), x.numpy()[:, 1::2])
+    y + y

imperative/src/impl/opr_utility.cpp

@@ -156,6 +156,12 @@ cg::OperatorNodeBase::NodeProp* OutputCallback::do_make_node_prop() const {
     return prop;
 }
 
+void OutputCallback::add_input_layout_constraint() {
+    if (m_param.require_contiguous) {
+        input(0)->add_layout_constraint_contiguous();
+    }
+}
+
 void OutputCallback::scn_do_execute() {
     if (m_use_host_value) {
         m_param.callback(owner_graph()->static_infer_manager().infer_value(input(0)));

imperative/src/include/megbrain/imperative/opr_utility.h

@@ -62,6 +62,7 @@ public:
         callback_t callback;
         bool borrow = false; // do not obtain shared ownership on DeviceTensorND
         bool prefer_host_value = false; // use host value when possible
+        bool require_contiguous = true;
     };
     OutputCallback(Param param,
                    const VarNodeArray& inputs,
@@ -80,6 +81,7 @@ protected:
     void scn_do_execute() override;
     void init_output_static_infer_desc() override;
     NodeProp* do_make_node_prop() const override;
+    void add_input_layout_constraint() override;
 private:
     Param m_param;
     mutable bool m_use_host_value;