fix(mgb/opr): fix convbias with no bias when weight preprocess

GitOrigin-RevId: 8837ad539cf4bd9f99a546996ee91cad31a03766

src/core/test/graph/misc.cpp

@@ -1976,7 +1976,6 @@ typename DnnOp::Algorithm* try_find_any_bias_preprocess_algo(
         bool valid = false;
         if (!layouts[1].is_empty()) {
             valid = true;
-            break;
         }
         if (valid) {
             found.emplace(true);
@@ -2204,6 +2203,8 @@ TEST(TestGraph, FreeBias) {
     param_conv_bias.sparse = opr::ConvBias::Param::Sparse::DENSE;
     auto w1 = mkcvar("w1", {32, 32, 1, 1}), b1 = mkcvar("b1", {1, 32, 1, 1});
     auto conv1 = opr::ConvBias::make(x, w1, b1, param_conv_bias);
+    auto w2 = mkcvar("w2", {32, 32, 1, 1});
+    auto conv2 = opr::ConvBias::make(conv1, w2, param_conv_bias);
     Maybe<bool> wp1;
     conv1.node()->owner_opr()->cast_final_safe<opr::ConvBias>()
         .setup_algo_chooser([&](const cg::OperatorNodeBase* opr) {
@@ -2216,7 +2217,7 @@ TEST(TestGraph, FreeBias) {
     });
 
     HostTensorND host_y;
-    auto func =graph->compile({make_callback_copy(conv1, host_y)});
+    auto func =graph->compile({make_callback_copy(conv2, host_y)});
     //!flag the no need memory of var
     func->execute();
     //!free the no need memory of var

src/opr/impl/dnn/convolution.cpp

@@ -960,11 +960,20 @@ void ConvBiasForward::scn_do_execute_preprocess() {
     if (input().size() > 3) {
         z_layout = input(3)->layout();
     }
-    megdnn_opr()->exec_preprocess(
-            input(0)->layout(), input(1)->dev_tensor().as_megdnn(),
-            input(2)->dev_tensor().as_megdnn(), z_layout, output(0)->layout(),
-            preprocessed_filter(),
-            intl::get_megdnn_workspace_from_var(output().back()));
+    if (input().size() > 2) {
+        megdnn_opr()->exec_preprocess(
+                input(0)->layout(), input(1)->dev_tensor().as_megdnn(),
+                input(2)->dev_tensor().as_megdnn(), z_layout,
+                output(0)->layout(), preprocessed_filter(),
+                intl::get_megdnn_workspace_from_var(output().back()));
+    } else {
+        megdnn::TensorND bias_tensor{nullptr, bias_layout};
+        megdnn_opr()->exec_preprocess(
+                input(0)->layout(), input(1)->dev_tensor().as_megdnn(),
+                bias_tensor, z_layout, output(0)->layout(),
+                preprocessed_filter(),
+                intl::get_megdnn_workspace_from_var(output().back()));
+    }
     //! Flag the weight and bias no use later, which can be freed when no other
     //! var depend on its dev_value, host_value and shape.
     auto receiver_info_weight =
@@ -975,7 +984,7 @@ void ConvBiasForward::scn_do_execute_preprocess() {
         input(1)->add_flag(VarNode::Flag::MEMORY_NO_NEED);
     }
     //! if bias is preprocessd
-    if (input().size() > 3) {
+    if (input().size() > 2) {
         auto preprocessed_layouts =
                 megdnn_opr()->deduce_preprocessed_filter_layout(
                         input(0)->layout(), input(1)->layout(), bias_layout,