feat(mgb/gopt): add an opt pass for padding channels to enable fast int8/int4 support on GPU

GitOrigin-RevId: 94c719bb5c

src/gopt/impl/tensor_reformat.cpp

@@ -3624,4 +3624,344 @@ void FoldingConvBiasDimshufflePass::apply(OptState& opt) const {
     MIDOUT_E
 }
 
+/* ==================== PaddingChaannelPass ================= */
+const char* PaddingChannelPass::name() const {
+    return mgb_cstr_log("padding output channel to multiple of 4/32");
+}
+
+void PaddingChannelPass::apply(OptState& opt) const {
+    MIDOUT_B("PaddingChannelPassPass::apply");
+    // do not check shape
+    opt.set_var_replace_check_flag(VarReplaceCheckFlag::CHECK_ALL ^
+                                   VarReplaceCheckFlag::CHECK_SHAPE);
+
+    ThinHashSet<OperatorNodeBase*> padding_oprs;
+    ThinHashMap<Typeinfo*, thin_function<OperatorNodeBase*(
+                                   OperatorNodeBase*, const VarNodeArray&)>>
+            opr_replace_funcs;
+
+    auto rewriter = opt.graph().make_rewriter();
+    auto pad_in_channels = [](VarNode* inp, size_t pad_channels) -> VarNode* {
+        mgb_assert(inp->shape().ndim == 4);
+        mgb_assert(inp->dtype().enumv() == DTypeEnum::QuantizedS8 ||
+                   inp->dtype().enumv() == DTypeEnum::QuantizedS32);
+        TensorShape shape{inp->shape()[0], pad_channels, inp->shape()[2],
+                          inp->shape()[3]};
+        std::shared_ptr<HostTensorND> host_val = std::make_shared<HostTensorND>(
+                inp->comp_node(), shape, inp->dtype());
+        auto ptr = host_val->raw_ptr();
+        std::memset(ptr, 0, shape.total_nr_elems() * inp->dtype().size());
+        auto padding =
+                opr::ImmutableTensor::make(*inp->owner_graph(), *host_val);
+        auto out = opr::Concat::make({inp, padding}, 1);
+        return out.node();
+    };
+
+    auto pad_out_channels = [](VarNode* inp, size_t pad_channels) -> VarNode* {
+        mgb_assert(inp->shape().ndim == 4);
+        mgb_assert(inp->dtype().enumv() == DTypeEnum::QuantizedS8 ||
+                   inp->dtype().enumv() == DTypeEnum::QuantizedS32);
+        TensorShape shape{pad_channels, inp->shape()[1], inp->shape()[2],
+                          inp->shape()[3]};
+        std::shared_ptr<HostTensorND> host_val = std::make_shared<HostTensorND>(
+                inp->comp_node(), shape, inp->dtype());
+        auto ptr = host_val->raw_ptr();
+        std::memset(ptr, 0, shape.total_nr_elems() * inp->dtype().size());
+        auto padding =
+                opr::ImmutableTensor::make(*inp->owner_graph(), *host_val);
+        auto out = opr::Concat::make({inp, padding}, 0);
+        return out.node();
+    };
+
+    auto extract_subtensor = [](VarNode* inp,
+                                size_t orig_channels) -> VarNode* {
+        mgb_assert(inp->shape().ndim == 4);
+        auto x = SymbolVar(inp);
+        auto cv = [&x](int v) { return x.make_scalar(v); };
+        using AIdx = opr::Subtensor::AxisIndexer;
+        auto sub = opr::Subtensor::make(
+                x, {AIdx::make_interval(0, None, None, cv(1)),
+                    AIdx::make_interval(1, None, cv(orig_channels), None),
+                    AIdx::make_interval(2, None, None, cv(1)),
+                    AIdx::make_interval(3, None, None, cv(1))});
+        return sub.node();
+    };
+
+    // padding policy for conv bias with data type qint8
+    auto padding_policy_qint8 = [&padding_oprs, &pad_in_channels,
+                                 &pad_out_channels](
+                                        OperatorNodeBase* opr,
+                                        const VarNodeArray& new_inp) {
+        mgb_assert(opr->input().size() == new_inp.size());
+        mgb_assert(new_inp.size() == 3);
+        mgb_assert(opr->input(1)->shape().eq_shape(new_inp[1]->shape()));
+        auto inps = new_inp;
+        size_t out_channels = opr->input(1)->shape()[0];
+        size_t in_channels = opr->input(1)->shape()[1];
+        size_t new_in_channels = new_inp[0]->shape()[1];
+        // pad input channels
+        if (padding_oprs.count(opr->input(0)->owner_opr())) {
+            size_t pad_channels = new_in_channels - in_channels;
+            inps[1] = pad_in_channels(new_inp[1], pad_channels);
+        } else {
+            size_t pad_channels = 0;
+            mgb_assert(new_in_channels == in_channels);
+            if (in_channels <= 16) {
+                if (in_channels % 4)
+                    pad_channels = 4 - (in_channels % 4);  // pad to use dp4a
+            } else {
+                if (in_channels % 32)
+                    pad_channels =
+                            32 - (in_channels % 32);  // pad to use tensorcore
+            }
+            if (pad_channels > 0) {
+                inps[0] = pad_in_channels(new_inp[0], pad_channels);
+                inps[1] = pad_in_channels(new_inp[1], pad_channels);
+            }
+        }
+        out_channels = inps[1]->shape()[0];
+        in_channels = inps[1]->shape()[1];
+        size_t pad_channels = 0;
+        if (in_channels <= 16) {
+            if (out_channels % 4)
+                pad_channels = 4 - (out_channels % 4);
+        } else {
+            if (out_channels <= 16) {
+                if (out_channels % 4)
+                    pad_channels = 4 - (out_channels % 4);
+            } else {
+                if (out_channels % 32)
+                    pad_channels = 32 - (out_channels % 32);
+            }
+        }
+        if (pad_channels > 0) {
+            inps[1] = pad_out_channels(inps[1], pad_channels);
+            inps[2] = pad_in_channels(inps[2], pad_channels);
+            padding_oprs.insert(opr);
+        }
+        return serialization::copy_opr_shallow(*opr, inps, opr->config());
+    };
+
+    // padding policy for conv bias with data type qint4 and quint4
+    auto padding_policy_int4 = [&padding_oprs, &pad_in_channels,
+                                &pad_out_channels](
+                                       OperatorNodeBase* opr,
+                                       const VarNodeArray& new_inp) {
+        mgb_assert(opr->input().size() == new_inp.size());
+        mgb_assert(new_inp.size() == 3);
+        mgb_assert(opr->input(1)->shape().eq_shape(new_inp[1]->shape()));
+        auto inps = new_inp;
+        return serialization::copy_opr_shallow(*opr, inps, opr->config());
+    };
+
+    opr_replace_funcs[opr::ConvBiasForward::typeinfo()] =
+            [&padding_oprs, &padding_policy_qint8, &padding_policy_int4](
+                    OperatorNodeBase* opr, const VarNodeArray& new_inp) {
+                if (opr->input(0)->dtype().enumv() == DTypeEnum::QuantizedS8) {
+                    return padding_policy_qint8(opr, new_inp);
+                } else if (opr->input(0)->dtype().enumv() ==
+                                   DTypeEnum::QuantizedS4 ||
+                           opr->input(0)->dtype().enumv() ==
+                                   DTypeEnum::Quantized4Asymm) {
+                    return padding_policy_int4(opr, new_inp);
+                } else {
+                    mgb_assert(
+                            padding_oprs.count(opr->input(0)->owner_opr()) == 0,
+                            "conv bias operator for data type(%s) cannot be "
+                            "padded channel. "
+                            "consumer(%s), producer(%s)",
+                            opr->input(0)->dtype().name(), opr->cname(),
+                            opr->input(0)->owner_opr()->cname());
+                    return serialization::copy_opr_shallow(*opr, new_inp,
+                                                           opr->config());
+                }
+            };
+    opr_replace_funcs[opr::ConvolutionBackwardData::typeinfo()] =
+            [&padding_oprs, &pad_in_channels, &pad_out_channels](
+                    OperatorNodeBase* opr, const VarNodeArray& new_inp) {
+                if (opr->input(1)->dtype().enumv() != DTypeEnum::QuantizedS8) {
+                    mgb_assert(
+                            padding_oprs.count(opr->input(0)->owner_opr()) == 0,
+                            "conv bwd data operator for data type(%s) cannot "
+                            "be "
+                            "padded channel. "
+                            "consumer(%s), producer(%s)",
+                            opr->input(0)->dtype().name(), opr->cname(),
+                            opr->input(0)->owner_opr()->cname());
+                    return serialization::copy_opr_shallow(*opr, new_inp,
+                                                           opr->config());
+                }
+                mgb_assert(opr->input().size() == new_inp.size());
+                mgb_assert(new_inp.size() == 2,
+                           "deconv (conv bwd data) operator for inference can "
+                           "only have 2 input vars(got:%zu)",
+                           new_inp.size());
+                mgb_assert(
+                        opr->input(0)->shape().eq_shape(new_inp[0]->shape()));
+                auto inps = new_inp;
+                size_t out_channels = opr->input(0)->shape()[0];
+                size_t in_channels = opr->input(0)->shape()[1];
+                size_t new_out_channels = new_inp[1]->shape()[1];
+                // pad output channels
+                if (padding_oprs.count(opr->input(1)->owner_opr())) {
+                    size_t pad_channels = new_out_channels - out_channels;
+                    inps[0] = pad_out_channels(new_inp[0], pad_channels);
+                } else {
+                    size_t pad_channels = 0;
+                    if (out_channels % 4)
+                        pad_channels = 4 - (out_channels % 4);
+                    if (pad_channels > 0) {
+                        inps[0] = pad_out_channels(new_inp[0], pad_channels);
+                        inps[1] = pad_in_channels(new_inp[1], pad_channels);
+                    }
+                }
+                out_channels = inps[0]->shape()[0];
+                in_channels = inps[0]->shape()[1];
+                // pad input channels
+                size_t pad_channels = 0;
+                if (in_channels % 4)
+                    pad_channels = 4 - (in_channels % 4);
+                if (pad_channels > 0) {
+                    inps[0] = pad_in_channels(inps[0], pad_channels);
+                    padding_oprs.insert(opr);
+                }
+                return serialization::copy_opr_shallow(*opr, inps,
+                                                       opr->config());
+            };
+    auto replace_format_aware_opr = [&padding_oprs](
+                                            OperatorNodeBase* opr,
+                                            const VarNodeArray& new_inp) {
+        if (opr->input(0)->dtype().enumv() != DTypeEnum::QuantizedS8 &&
+            opr->input(0)->dtype().enumv() != DTypeEnum::QuantizedS4 &&
+            opr->input(0)->dtype().enumv() != DTypeEnum::Quantized4Asymm) {
+            mgb_assert(padding_oprs.count(opr->input(0)->owner_opr()) == 0,
+                       "operator(type:%s,name:%s) for data type(%s) cannot be "
+                       "padded channel. extra info:"
+                       "consumer(%s), producer(%s)",
+                       opr->dyn_typeinfo()->name, opr->cname(),
+                       opr->input(0)->dtype().name(), opr->cname(),
+                       opr->input(0)->owner_opr()->cname());
+            return serialization::copy_opr_shallow(*opr, new_inp,
+                                                   opr->config());
+        }
+        mgb_assert(opr->input().size() == new_inp.size());
+        if (padding_oprs.count(opr->input(0)->owner_opr())) {
+            padding_oprs.insert(opr);
+        }
+        return serialization::copy_opr_shallow(*opr, new_inp, opr->config());
+    };
+    opr_replace_funcs[opr::PoolingForward::typeinfo()] =
+            replace_format_aware_opr;
+    opr_replace_funcs[opr::WarpPerspectiveForward::typeinfo()] =
+            replace_format_aware_opr;
+
+    auto replace_elemwise_like_opr = [&padding_oprs, &extract_subtensor](
+                                             OperatorNodeBase* opr,
+                                             const VarNodeArray& new_inp) {
+        mgb_assert(opr->input().size() == new_inp.size());
+        bool have_padding_inp = false;
+        bool padding_all_inps = true;
+        bool same_padding = true;
+        size_t channels_after_padding = 0;
+        for (auto&& cur_inp : opr->input()) {
+            bool padding_cur_inp = padding_oprs.count(cur_inp->owner_opr()) > 0;
+            if (padding_cur_inp) {
+                if (!have_padding_inp)
+                    have_padding_inp = true;
+                if (channels_after_padding == 0) {
+                    channels_after_padding = cur_inp->shape()[1];
+                } else {
+                    same_padding =
+                            channels_after_padding == cur_inp->shape()[1];
+                }
+            }
+            if (padding_all_inps && (!padding_cur_inp || !same_padding))
+                padding_all_inps = false;
+        }
+        if (have_padding_inp && !padding_all_inps) {
+            auto inps = new_inp;
+            for (size_t i = 0; i < new_inp.size(); ++i) {
+                auto cur_inp = opr->input(i);
+                bool padding_cur_inp =
+                        padding_oprs.count(cur_inp->owner_opr()) > 0;
+                if (padding_cur_inp) {
+                    size_t orig_channels = cur_inp->shape()[1];
+                    inps[i] = extract_subtensor(inps[i], orig_channels);
+                }
+            }
+            return serialization::copy_opr_shallow(*opr, inps, opr->config());
+        }
+        if (padding_all_inps) {
+            padding_oprs.insert(opr);
+        }
+        return serialization::copy_opr_shallow(*opr, new_inp, opr->config());
+    };
+    opr_replace_funcs[opr::ElemwiseMultiType::typeinfo()] =
+            replace_elemwise_like_opr;
+    opr_replace_funcs[opr::Elemwise::typeinfo()] = replace_elemwise_like_opr;
+    opr_replace_funcs[opr::TypeCvt::typeinfo()] = replace_elemwise_like_opr;
+
+    auto replace_nonpadding_oprs = [&padding_oprs, &extract_subtensor](
+                                           OperatorNodeBase* opr,
+                                           const VarNodeArray& new_inp) {
+        mgb_assert(opr->input().size() == new_inp.size());
+        bool have_padding_inp = false;
+        auto inps = new_inp;
+        for (size_t i = 0; i < new_inp.size(); ++i) {
+            auto cur_inp = opr->input(i);
+            bool padding_cur_inp = padding_oprs.count(cur_inp->owner_opr()) > 0;
+            if (padding_cur_inp) {
+                if (!have_padding_inp)
+                    have_padding_inp = true;
+                size_t orig_channels = cur_inp->shape()[1];
+                inps[i] = extract_subtensor(inps[i], orig_channels);
+            }
+        }
+        return serialization::copy_opr_shallow(*opr, inps, opr->config());
+    };
+    opr_replace_funcs[opr::Reshape::typeinfo()] = replace_nonpadding_oprs;
+    opr_replace_funcs[opr::GetVarShape::typeinfo()] = replace_nonpadding_oprs;
+    opr_replace_funcs[opr::Concat::typeinfo()] = replace_nonpadding_oprs;
+
+    auto on_opr = [&opt, &rewriter, &opr_replace_funcs,
+                   &extract_subtensor](OperatorNodeBase* opr) {
+        auto it = opr_replace_funcs.find(opr->dyn_typeinfo());
+        if (it != opr_replace_funcs.end()) {
+            VarNodeArray new_inp;
+            new_inp.reserve(opr->input().size());
+            for (auto&& inp : opr->input()) {
+                new_inp.push_back(rewriter.get_var(inp));
+            }
+            auto new_opr = (it->second)(opr, new_inp);
+            auto &&out0 = opr->output(), &&out1 = new_opr->output();
+            mgb_assert(out0.size() == out1.size(),
+                       "bad opr replace: src=%s{%s} dst=%s{%s}, "
+                       "src.size=%zu "
+                       "dst.size=%zu",
+                       opr->cname(), opr->dyn_typeinfo()->name,
+                       new_opr->cname(), new_opr->dyn_typeinfo()->name,
+                       out0.size(), out1.size());
+            for (size_t i = 0; i < out0.size(); ++i) {
+                if (!out0[i]->contain_flag(VarNode::Flag::VOLATILE_CONTENT)) {
+                    mgb_assert(!out1[i]->contain_flag(
+                            VarNode::Flag::VOLATILE_CONTENT));
+                    auto src = out0[i];
+                    auto dst = out1[i];
+                    if (opt.graph().endpoint_contain(src) &&
+                        !src->shape().eq_shape(dst->shape())) {
+                        size_t orig_channels = src->shape()[1];
+                        dst = extract_subtensor(dst, orig_channels);
+                    }
+                    rewriter.replace_var(src, dst, nullptr);
+                }
+            }
+        } else {
+            rewriter.auto_replace_outputs(opr);
+        }
+    };
+    opt.graph().iter(on_opr);
+    rewriter.apply_inplace();
+
+    MIDOUT_E
+}
 // vim: syntax=cpp.doxygen foldmethod=marker foldmarker=f{{{,f}}}

src/gopt/include/megbrain/gopt/inference.h

@@ -409,6 +409,16 @@ namespace gopt {
             void apply(OptState& opt) const override;
     };
 
+    /*!
+     * \brief padding channel to enable fast int8/int4 support
+     * assume input network is built in NCHW tensor format
+     */
+    class PaddingChannelPass final : public Pass {
+        public:
+            const char* name() const override;
+            void apply(OptState& opt) const override;
+    };
+
 }  // namespace gopt
 } // namespace mgb
 

src/gopt/test/inference.cpp

@@ -4178,6 +4178,313 @@ TEST(TestGoptInference, FoldingConvDimshuffleNCHW32NCHW4) {
     MGB_ASSERT_TENSOR_EQ(host_y_fuse, host_y_non_fuse);
 }
 #endif
+
+TEST(TestGoptInference, PaddingChannels) {
+    REQUIRE_GPU(1);
+    auto cn = CompNode::load("gpu0");
+    cn.activate();
+    auto&& prop = CompNodeEnv::from_comp_node(cn).cuda_env().device_prop;
+    auto sm_ver = prop.major * 10 + prop.minor;
+    if (sm_ver < 61) {
+        printf("This testcast ignored due to insufficient cuda cap(got: %d, "
+               "expected: %d)\n",
+               sm_ver, 61);
+        return;
+    }
+
+    HostTensorGenerator<dtype::Int8> gen;
+    auto graph = ComputingGraph::make();
+    graph->options().graph_opt_level = 0;
+    auto mkvar = [&](const char* name, const TensorShape& shp,
+                     const DType& dtype) {
+        return opr::TypeCvt::make(
+                opr::Host2DeviceCopy::make(*graph, gen(shp, cn)).rename(name),
+                dtype);
+    };
+    auto mkcvar = [&](const char* name, const TensorShape& shp,
+                      const DType& dtype) {
+        return opr::TypeCvt::make(
+                opr::SharedDeviceTensor::make(*graph, *gen(shp, cn))
+                        .rename(name),
+                dtype);
+    };
+
+    auto x = mkvar("x", {16, 3, 14, 14}, dtype::QuantizedS8(2.5f)),
+         w = mkcvar("w", {20, 3, 3, 3}, dtype::QuantizedS8(2.5f)),
+         b = mkcvar("b", {1, 20, 1, 1}, dtype::QuantizedS32(6.25f));
+    opr::ConvBias::Param param;
+    param.format = opr::ConvBias::Param::Format::NCHW;
+    param.nonlineMode = opr::ConvBias::Param::NonlineMode::RELU;
+    param.stride_h = param.stride_w = 1;
+    param.pad_h = param.pad_w = 1;
+
+    auto y = opr::ConvBias::make(x, w, b, param, {},
+                                 OperatorNodeConfig{dtype::QuantizedS8(2.5f)});
+    auto w1 = mkcvar("w1", {24, 20, 3, 3}, dtype::QuantizedS8(2.5f)),
+         b1 = mkcvar("b1", {1, 24, 1, 1}, dtype::QuantizedS32(6.25f));
+    auto y1 = opr::ConvBias::make(y, w1, b1, param, {},
+                            OperatorNodeConfig{dtype::QuantizedS8(2.5f)});
+    auto w2 = mkcvar("w2", {20, 24, 3, 3}, dtype::QuantizedS8(2.5f)),
+         b2 = mkcvar("b2", {1, 20, 1, 1}, dtype::QuantizedS32(6.25f));
+    auto y2 = opr::ConvBias::make(y1, w2, b2, param, {},
+                            OperatorNodeConfig{dtype::QuantizedS8(2.5f)});
+    using ElemMultiMode = opr::ElemwiseMultiType::Param::Mode;
+    auto y3 = opr::ElemwiseMultiType::make(
+            {y, y2}, {ElemMultiMode::QFUSE_ADD_RELU},
+            OperatorNodeConfig{dtype::QuantizedS8{1.2f}});
+    y3 = opr::TypeCvt::make(y3, dtype::Float32());
+    SymbolVar y3_pad;
+    unpack_vector(gopt::GraphOptimizer{}
+                          .add_pass<gopt::PaddingChannelPass>()
+                          .apply({{y3}})
+                          .endpoint_vars(),
+                  y3_pad);
+    ASSERT_EQ(y3_pad.node()->shape()[1], y3.node()->shape()[1]);
+    SmallVector<cg::OperatorNodeBase*> oprs;
+    auto cb = [&oprs](cg::OperatorNodeBase* opr) {
+        if (opr->same_type<opr::ConvBias>()) {
+            oprs.push_back(opr);
+        }
+    };
+    cg::DepOprIter{cb}.add(y3_pad.node()->owner_opr());
+    ASSERT_EQ(oprs.size(), 3);
+    ASSERT_EQ(oprs[0]->output(0)->shape()[1], 20);
+    ASSERT_EQ(oprs[1]->output(0)->shape()[1], 32);
+    ASSERT_EQ(oprs[2]->output(0)->shape()[1], 32);
+    HostTensorND t1, t2;
+    auto func1 = graph->compile({make_callback_copy(y3, t1)});
+    func1->execute();
+    auto func2 = graph->compile({make_callback_copy(y3_pad, t2)});
+    func2->execute();
+    MGB_ASSERT_TENSOR_EQ(t1, t2);
+}
+
+TEST(TestGoptInference, ConcatAfterPaddingChannels) {
+    REQUIRE_GPU(1);
+    auto cn = CompNode::load("gpu0");
+    cn.activate();
+    auto&& prop = CompNodeEnv::from_comp_node(cn).cuda_env().device_prop;
+    auto sm_ver = prop.major * 10 + prop.minor;
+    if (sm_ver < 61) {
+        printf("This testcast ignored due to insufficient cuda cap(got: %d, "
+               "expected: %d)\n",
+               sm_ver, 61);
+        return;
+    }
+
+    HostTensorGenerator<dtype::Int8> gen;
+    auto graph = ComputingGraph::make();
+    graph->options().graph_opt_level = 0;
+    auto mkvar = [&](const char* name, const TensorShape& shp,
+                     const DType& dtype) {
+        return opr::TypeCvt::make(
+                opr::Host2DeviceCopy::make(*graph, gen(shp, cn)).rename(name),
+                dtype);
+    };
+    auto mkcvar = [&](const char* name, const TensorShape& shp,
+                      const DType& dtype) {
+        return opr::TypeCvt::make(
+                opr::SharedDeviceTensor::make(*graph, *gen(shp, cn))
+                        .rename(name),
+                dtype);
+    };
+
+    auto x = mkvar("x", {16, 3, 14, 14}, dtype::QuantizedS8(2.5f)),
+         w = mkcvar("w", {18, 3, 3, 3}, dtype::QuantizedS8(2.5f)),
+         b = mkcvar("b", {1, 18, 1, 1}, dtype::QuantizedS32(6.25f));
+    opr::ConvBias::Param param;
+    param.format = opr::ConvBias::Param::Format::NCHW;
+    param.nonlineMode = opr::ConvBias::Param::NonlineMode::RELU;
+    param.stride_h = param.stride_w = 1;
+    param.pad_h = param.pad_w = 1;
+
+    auto y = opr::ConvBias::make(x, w, b, param, {},
+                                 OperatorNodeConfig{dtype::QuantizedS8(2.5f)});
+    auto w1 = mkcvar("w1", {18, 18, 3, 3}, dtype::QuantizedS8(2.5f)),
+         b1 = mkcvar("b1", {1, 18, 1, 1}, dtype::QuantizedS32(6.25f));
+    auto y1 = opr::ConvBias::make(y, w1, b1, param, {},
+                            OperatorNodeConfig{dtype::QuantizedS8(2.5f)});
+    // concat at batch dim
+    auto y2 = opr::Concat::make({y, y1}, 0);
+    y2 = opr::TypeCvt::make(y2, dtype::Float32());
+    SymbolVar y2_pad;
+    unpack_vector(gopt::GraphOptimizer{}
+                          .add_pass<gopt::PaddingChannelPass>()
+                          .apply({{y2}})
+                          .endpoint_vars(),
+                  y2_pad);
+    ASSERT_EQ(y2_pad.node()->shape()[1], y2.node()->shape()[1]);
+    SmallVector<cg::OperatorNodeBase*> oprs;
+    auto cb = [&oprs](cg::OperatorNodeBase* opr) {
+        if (opr->same_type<opr::ConvBias>()) {
+            oprs.push_back(opr);
+        }
+    };
+    cg::DepOprIter{cb}.add(y2_pad.node()->owner_opr());
+    ASSERT_EQ(oprs.size(), 2);
+    ASSERT_EQ(oprs[0]->output(0)->shape()[1], 20);
+    ASSERT_EQ(oprs[1]->output(0)->shape()[1], 32);
+    HostTensorND t1, t2;
+    auto func1 = graph->compile({make_callback_copy(y2, t1)});
+    func1->execute();
+    auto func2 = graph->compile({make_callback_copy(y2_pad, t2)});
+    func2->execute();
+    MGB_ASSERT_TENSOR_EQ(t1, t2);
+}
+
+// FIXME replace cpu with gpu to enable gpu validation
+TEST(TestGoptInference, PaddingChannelsWithPooling) {
+    REQUIRE_GPU(1);
+    auto cn = CompNode::load("cpu0");
+//    cn.activate();
+//    auto&& prop = CompNodeEnv::from_comp_node(cn).cuda_env().device_prop;
+//    auto sm_ver = prop.major * 10 + prop.minor;
+//    if (sm_ver < 61) {
+//        printf("This testcast ignored due to insufficient cuda cap(got: %d, "
+//               "expected: %d)\n",
+//               sm_ver, 61);
+//        return;
+//    }
+
+    HostTensorGenerator<dtype::Int8> gen;
+    auto graph = ComputingGraph::make();
+    graph->options().graph_opt_level = 0;
+    auto mkvar = [&](const char* name, const TensorShape& shp,
+                     const DType& dtype) {
+        return opr::TypeCvt::make(
+                opr::Host2DeviceCopy::make(*graph, gen(shp, cn)).rename(name),
+                dtype);
+    };
+    auto mkcvar = [&](const char* name, const TensorShape& shp,
+                      const DType& dtype) {
+        return opr::TypeCvt::make(
+                opr::SharedDeviceTensor::make(*graph, *gen(shp, cn))
+                        .rename(name),
+                dtype);
+    };
+
+    auto x = mkvar("x", {16, 3, 14, 14}, dtype::QuantizedS8(2.5f)),
+         w = mkcvar("w", {20, 3, 3, 3}, dtype::QuantizedS8(2.5f)),
+         b = mkcvar("b", {1, 20, 1, 1}, dtype::QuantizedS32(6.25f));
+    opr::ConvBias::Param param;
+    param.format = opr::ConvBias::Param::Format::NCHW;
+    param.nonlineMode = opr::ConvBias::Param::NonlineMode::RELU;
+    param.stride_h = param.stride_w = 1;
+    param.pad_h = param.pad_w = 1;
+
+    auto y = opr::ConvBias::make(x, w, b, param, {},
+                                 OperatorNodeConfig{dtype::QuantizedS8(2.5f)});
+    auto w1 = mkcvar("w1", {24, 20, 3, 3}, dtype::QuantizedS8(2.5f)),
+         b1 = mkcvar("b1", {1, 24, 1, 1}, dtype::QuantizedS32(6.25f));
+    auto y1 = opr::ConvBias::make(y, w1, b1, param, {},
+                            OperatorNodeConfig{dtype::QuantizedS8(2.5f)});
+
+    opr::Pooling::Param pool_param;
+    pool_param.format = opr::Pooling::Param::Format::NCHW;
+    y1 = opr::Pooling::make(y1, pool_param);
+    y1 = opr::TypeCvt::make(y1, dtype::Float32());
+    SymbolVar y1_pad;
+    unpack_vector(gopt::GraphOptimizer{}
+                          .add_pass<gopt::PaddingChannelPass>()
+                          .apply({{y1}})
+                          .endpoint_vars(),
+                  y1_pad);
+    ASSERT_EQ(y1_pad.node()->shape()[1], y1.node()->shape()[1]);
+    SmallVector<cg::OperatorNodeBase*> oprs;
+    auto cb = [&oprs](cg::OperatorNodeBase* opr) {
+        if (opr->same_type<opr::Pooling>()) {
+            oprs.push_back(opr);
+        }
+    };
+    cg::DepOprIter{cb}.add(y1_pad.node()->owner_opr());
+    ASSERT_EQ(oprs[0]->output(0)->shape()[1], 32);
+    HostTensorND t1, t2;
+    auto func1 = graph->compile({make_callback_copy(y1, t1)});
+    func1->execute();
+    auto func2 = graph->compile({make_callback_copy(y1_pad, t2)});
+    func2->execute();
+    MGB_ASSERT_TENSOR_EQ(t1, t2);
+}
+
+// FIXME replace cpu with gpu to enable gpu validation
+TEST(TestGoptInference, PaddingChannelsWithWarpPerspective) {
+    REQUIRE_GPU(1);
+    auto cn = CompNode::load("cpu0");
+//    cn.activate();
+//    auto&& prop = CompNodeEnv::from_comp_node(cn).cuda_env().device_prop;
+//    auto sm_ver = prop.major * 10 + prop.minor;
+//    if (sm_ver < 61) {
+//        printf("This testcast ignored due to insufficient cuda cap(got: %d, "
+//               "expected: %d)\n",
+//               sm_ver, 61);
+//        return;
+//    }
+
+    HostTensorGenerator<dtype::Int8> gen;
+    auto graph = ComputingGraph::make();
+    graph->options().graph_opt_level = 0;
+    auto mkvar = [&](const char* name, const TensorShape& shp,
+                     const DType& dtype) {
+        return opr::TypeCvt::make(
+                opr::Host2DeviceCopy::make(*graph, gen(shp, cn)).rename(name),
+                dtype);
+    };
+    auto mkcvar = [&](const char* name, const TensorShape& shp,
+                      const DType& dtype) {
+        return opr::TypeCvt::make(
+                opr::SharedDeviceTensor::make(*graph, *gen(shp, cn))
+                        .rename(name),
+                dtype);
+    };
+
+    std::shared_ptr<HostTensorND> mat = std::make_shared<HostTensorND>(
+            cn, TensorShape{16, 3, 3}, dtype::Float32());
+    warp_perspective_mat_gen(*mat, 16, 14, 14);
+    auto mat_var = opr::Host2DeviceCopy::make(*graph, mat).rename("mat");
+
+    auto x = mkvar("x", {16, 3, 14, 14}, dtype::QuantizedS8(2.5f)),
+         w = mkcvar("w", {20, 3, 3, 3}, dtype::QuantizedS8(2.5f)),
+         b = mkcvar("b", {1, 20, 1, 1}, dtype::QuantizedS32(6.25f));
+    opr::ConvBias::Param param;
+    param.format = opr::ConvBias::Param::Format::NCHW;
+    param.nonlineMode = opr::ConvBias::Param::NonlineMode::RELU;
+    param.stride_h = param.stride_w = 1;
+    param.pad_h = param.pad_w = 1;
+
+    auto y = opr::ConvBias::make(x, w, b, param, {},
+                                 OperatorNodeConfig{dtype::QuantizedS8(2.5f)});
+    auto w1 = mkcvar("w1", {24, 20, 3, 3}, dtype::QuantizedS8(2.5f)),
+         b1 = mkcvar("b1", {1, 24, 1, 1}, dtype::QuantizedS32(6.25f));
+    auto y1 = opr::ConvBias::make(y, w1, b1, param, {},
+                            OperatorNodeConfig{dtype::QuantizedS8(2.5f)});
+
+    opr::WarpPerspective::Param warp_param;
+    warp_param.format = opr::WarpPerspective::Param::Format::NCHW;
+    y1 = opr::WarpPerspective::make(y1, mat_var, TensorShape{14, 14},
+                                    warp_param);
+    y1 = opr::TypeCvt::make(y1, dtype::Float32());
+    SymbolVar y1_pad;
+    unpack_vector(gopt::GraphOptimizer{}
+                          .add_pass<gopt::PaddingChannelPass>()
+                          .apply({{y1}})
+                          .endpoint_vars(),
+                  y1_pad);
+    ASSERT_EQ(y1_pad.node()->shape()[1], y1.node()->shape()[1]);
+    SmallVector<cg::OperatorNodeBase*> oprs;
+    auto cb = [&oprs](cg::OperatorNodeBase* opr) {
+        if (opr->same_type<opr::WarpPerspective>()) {
+            oprs.push_back(opr);
+        }
+    };
+    cg::DepOprIter{cb}.add(y1_pad.node()->owner_opr());
+    ASSERT_EQ(oprs[0]->output(0)->shape()[1], 32);
+    HostTensorND t1, t2;
+    auto func1 = graph->compile({make_callback_copy(y1, t1)});
+    func1->execute();
+    auto func2 = graph->compile({make_callback_copy(y1_pad, t2)});
+    func2->execute();
+    MGB_ASSERT_TENSOR_EQ(t1, t2);
+}
 #endif
 
 // vim: syntax=cpp.doxygen foldmethod=marker foldmarker=f{{{,f}}}