[Relay] Alter Op Layout (#2150)

* [RELAY] Finish alter op pass

* [RELAY] AlterOpLayout Pass

* fix broadcast operators

* fix broadcast operators

* fix broadcast operators

* Support concatenate

* address comments

* address comments

* add comments

* rebase

HalideIR @ a08e26e5

-Subproject commit e4a4c02764d37c9c3db0d64c4996651a3ef9513c
+Subproject commit a08e26e5a97f4ef4d566a42f6c78704b3f9c7b8a

include/tvm/relay/attrs/nn.h

@@ -105,6 +105,7 @@ struct Conv2DTransposeAttrs : public tvm::AttrsNode<Conv2DTransposeAttrs> {
   int groups;
   std::string data_layout;
   std::string weight_layout;
+  std::string out_layout;
   DataType out_dtype;
 
   TVM_DECLARE_ATTRS(Conv2DTransposeAttrs, "relay.attrs.Conv2DTransposeAttrs") {
@@ -139,6 +140,10 @@ struct Conv2DTransposeAttrs : public tvm::AttrsNode<Conv2DTransposeAttrs> {
       .describe("Dimension ordering of data and weight. Can be 'OIHW', 'OIHW16o16i', etc."
                 "'O', 'I', 'H', 'W' stands for num_filter, input_channel, height, and width"
                 "dimensions respectively.");
+    TVM_ATTR_FIELD(out_layout).set_default("")
+        .describe("Dimension ordering of output. Can be 'NCHW', 'NHWC', etc."
+                      "'N', 'C', 'H', 'W' stands for batch, channel, height, and width"
+                      "dimensions respectively. Default to be same as input layout.");
     TVM_ATTR_FIELD(out_dtype)
         .set_default(NullValue<DataType>())
         .describe("Output data type, set to explicit type under mixed precision setting");

include/tvm/relay/attrs/transform.h

@@ -164,6 +164,19 @@ struct ClipAttrs : public tvm::AttrsNode<ClipAttrs> {
   }
 };
 
+
+struct LayoutTransformAttrs : public tvm::AttrsNode<LayoutTransformAttrs> {
+  std::string src_layout;
+  std::string dst_layout;
+
+  TVM_DECLARE_ATTRS(LayoutTransformAttrs, "relay.attrs.LayoutTransformAttrs") {
+    TVM_ATTR_FIELD(src_layout)
+        .describe("The source layout of the tensor. (e.g. NCHW)");
+    TVM_ATTR_FIELD(dst_layout)
+        .describe("The destination layout of the tensor. (e.g. NCHW16c)");
+  }
+};
+
 }  // namespace relay
 }  // namespace tvm
 #endif  // TVM_RELAY_ATTRS_TRANSFORM_H_

include/tvm/relay/expr.h

@@ -459,7 +459,7 @@ inline const TTypeNode* ExprNode::type_as() const {
   static_assert(std::is_base_of<TypeNode, TTypeNode>::value,
                 "TType must be a special case of type");
   CHECK(checked_type_.defined())
-      << "Type inference for this Expr has not completed";
+      << "Type inference for this Expr has not completed. Try to call infer_type pass.";
   const TTypeNode* node = checked_type_.as<TTypeNode>();
   CHECK(node != nullptr)
       << "Expected type to be " << TTypeNode::_type_key

include/tvm/relay/op_attr_types.h

@@ -87,6 +87,21 @@ using FTVMSchedule = runtime::TypedPackedFunc<
            const Target& target)>;
 
 /*!
+ * \brief Alternate the layout of operators or replace the
+ *  operator with other expressions. This function will be invoked
+ *  in AlterOpLayout pass.
+ * \param attrs The attribute of the original node.
+ * \param inputs The input symbols of the original node.
+ * \param tinfos An array of placeholders, use for getting the inferred shape
+ *               and dtype of the inputs.
+ * \return new_expr The modified expression.
+ */
+using FTVMAlterOpLayout = runtime::TypedPackedFunc<
+  Expr(const Attrs& attrs,
+       const Array<Expr>& args,
+       const Array<Tensor>& tinfos)>;
+
+/*!
  * \brief Forward rewriting rule for a specific op.
  *
  * \param ref_call The reference old call type to be rewritten.

include/tvm/relay/pass.h

@@ -8,6 +8,7 @@
 
 #include <tvm/relay/module.h>
 #include <tvm/relay/expr.h>
+#include <tvm/relay/op_attr_types.h>
 #include <string>
 
 namespace tvm {
@@ -173,6 +174,21 @@ Expr ForwardRewrite(const Expr& expr,
                     std::function<NodeRef(const Call&)> fcontext = nullptr,
                     std::function<Expr(const Expr&)> fmulti_ref_trigger = nullptr);
 
+/*!
+ * \brief Apply rewrite rules to rewrite the expr in post DFS order.
+ * \param expr The expression.
+ * \param rewrite_func The rewrite func that will apply to all operators.
+ * \param fcontext Additional callback to provide context argument for each call node.
+ * \param fmulti_ref_trigger Transformation function to be called when
+ *                           an Expr consumed by multiple callers.
+ * \return The rewritten expression.
+ */
+Expr ForwardRewrite(const Expr& expr,
+                    const FForwardRewrite& rewrite_func,
+                    std::function<NodeRef(const Call&)> fcontext = nullptr,
+                    std::function<Expr(const Expr&)> fmulti_ref_trigger = nullptr);
+
+
 /*! \brief A hashing structure in the style of std::hash. */
 struct StructuralHash {
   /*! \brief Hash a Relay type.

python/tvm/__init__.py

@@ -13,6 +13,7 @@ from . import container
 from . import schedule
 from . import module
 from . import node
+from . import attrs
 from . import ir_builder
 from . import target
 from . import generic

python/tvm/attrs.py

+""" TVM Attribute module, which is mainly used for defining attributes of operators"""
+from ._ffi.node import NodeBase, register_node as _register_tvm_node
+from ._ffi.function import _init_api
+from . import _api_internal
+
+
+@_register_tvm_node
+class Attrs(NodeBase):
+    """Attribute node, which is mainly use for defining attributes of relay operators.
+
+    Used by function registered in python side, such as compute, schedule and alter_layout.
+    Attrs is passed as the first argument to these functions.
+    """
+    def list_field_info(self):
+        """ Get fields information
+
+        Returns
+        -------
+        infos: list of AttrFieldInfo
+            List of field information
+        """
+        return _api_internal._AttrsListFieldInfo(self)
+
+    def keys(self):
+        """Get list of names in the attribute.
+
+        Returns
+        -------
+        keys : list of str
+            List of keys
+        """
+        fields = self.list_field_info()
+        for field in fields:
+            yield field.name
+
+    def __getitem__(self, item):
+        return self.__getattr__(item)
+
+
+_init_api("tvm.attrs")

python/tvm/relay/base.py

@@ -21,6 +21,20 @@ def register_relay_node(type_key=None):
     return _register_tvm_node(type_key)
 
 
+def register_relay_attr_node(type_key=None):
+    """register relay attribute node
+
+    Parameters
+    ----------
+    type_key : str or cls
+        The type key of the node
+    """
+    if not isinstance(type_key, str):
+        return _register_tvm_node(
+            "relay.attrs." + type_key.__name__)(type_key)
+    return _register_tvm_node(type_key)
+
+
 class RelayNode(NodeBase):
     """Base class of all relay node."""
     def astext(self, show_meta_data=True, annotate=None):

python/tvm/relay/build_module.py

@@ -17,6 +17,7 @@ OPT_PASS_LEVEL = {
     "FoldConstant": 2,
     "CombineParallelConv2D": 3,
     "FoldScaleAxis": 3,
+    "AlterOpLayout": 3,
 }
 
 class BuildConfig(object):
@@ -157,6 +158,13 @@ def optimize(func, params=None):
 
     if cfg.pass_enabled("FoldConstant"):
         func = ir_pass.fold_constant(func)
+
+    if cfg.pass_enabled("AlterOpLayout"):
+        func = ir_pass.infer_type(func)
+        func = ir_pass.canonicalize_ops(func)
+        func = ir_pass.infer_type(func)
+        func = ir_pass.alter_op_layout(func)
+
     return func
 
 

python/tvm/relay/ir_pass.py

@@ -191,6 +191,23 @@ def simplify_inference(expr):
     return _ir_pass.simplify_inference(expr)
 
 
+def canonicalize_ops(expr):
+    """ Canonicalize special operators to basic operators.
+    This can simplify latter analysis. (e.g. Expand bias_add to expand_dims and broadcast_add.)
+
+    Parameters
+    ----------
+    e: tvm.relay.Expr
+        The input Expression
+
+    Returns
+    -------
+    result: tvm.relay.Expr
+        An expression without bias_add
+    """
+    return _ir_pass.canonicalize_ops(expr)
+
+
 def dead_code_elimination(expr):
     """ Remove expressions which does not effect the program result (dead code).
 
@@ -321,3 +338,22 @@ def combine_parallel_conv2d(expr):
         Transformed expression
     """
     return _ir_pass.CombineParallelConv2D(expr)
+
+
+def alter_op_layout(expr):
+    """Alternate the layouts of operators or replace primitive operators with
+    other expressions.
+    This pass can be used for computing convolution in custom layouts or
+    other general weight pre-transformation.
+
+    Parameters
+    ----------
+    expr : tvm.relay.Expr
+        The input expression.
+
+    Returns
+    -------
+    transformed_expr : tvm.relay.Expr
+        Transformed expression with alternated layout.
+    """
+    return _ir_pass.AlterOpLayout(expr)

python/tvm/relay/op/__init__.py

 #pylint: disable=wildcard-import, redefined-builtin
 """Relay core operators."""
 # operator defs
-from .op import get, register, register_schedule, register_compute, Op
+from .op import get, register, register_schedule, register_compute, register_alter_op_layout, \
+    Op
 
 # Operators
 from .reduce import *
@@ -10,6 +11,7 @@ from .transform import *
 from . import nn
 from . import image
 from . import vision
+from . import op_attrs
 
 # operator registry
 from . import _tensor

python/tvm/relay/op/_tensor.py

@@ -80,12 +80,3 @@ def clip_compute(attrs, inputs, output_type, target):
     return [topi.clip(inputs[0], attrs.a_min, attrs.a_max)]
 
 register_schedule("clip", schedule_elemwise)
-register_pattern("clip", OpPattern.ELEMWISE)
-
-# concatenate
-@register_compute("concatenate")
-def concatenate_compute(attrs, inputs, output_type, target):
-    return [topi.concatenate(inputs, axis=attrs.axis)]
-
-register_schedule("concatenate", schedule_injective)
-register_pattern("concatenate", OpPattern.INJECTIVE)

python/tvm/relay/op/_transform.py

 """Backend compiler related feature registration"""
-# pylint: disable=invalid-name
+# pylint: disable=invalid-name,unused-argument
 from __future__ import absolute_import
+import topi
 from . import op as _reg
 from ._reduce import _schedule_reduce
+from .op import schedule_injective, OpPattern
 
 schedule_injective = _reg.schedule_injective
 schedule_broadcast = _reg.schedule_injective
@@ -15,10 +17,22 @@ _reg.register_schedule("reshape", schedule_injective)
 _reg.register_schedule("reshape_like", schedule_injective)
 _reg.register_schedule("full", schedule_injective)
 _reg.register_schedule("full_like", schedule_injective)
-_reg.register_schedule("cast", schedule_broadcast)
+_reg.register_schedule("cast", schedule_injective)
 _reg.register_schedule("strided_slice", schedule_injective)
 _reg.register_schedule("slice_like", schedule_injective)
 _reg.register_schedule("split", schedule_injective)
 _reg.register_schedule("take", schedule_injective)
 _reg.register_schedule("transpose", schedule_injective)
 _reg.register_schedule("where", schedule_broadcast)
+
+# layout_transform
+_reg.register_schedule("layout_transform", schedule_injective)
+_reg.register_pattern("layout_transform", OpPattern.INJECTIVE)
+
+# concatenate
+@_reg.register_compute("concatenate")
+def concatenate_compute(attrs, inputs, output_type, target):
+    return [topi.concatenate(inputs, axis=attrs.axis)]
+
+_reg.register_schedule("concatenate", schedule_injective)
+_reg.register_pattern("concatenate", OpPattern.INJECTIVE)

python/tvm/relay/op/op.py

@@ -107,7 +107,7 @@ def register_schedule(op_name, schedule=None, level=10):
     op_name : str
         The name of the op.
 
-    schedule : function
+    schedule : function (attrs: Attrs, outs: List[Tensor], target: Target) -> sch: Schedule
         The schedule function.
 
     level : int
@@ -124,7 +124,8 @@ def register_compute(op_name, compute=None, level=10):
     op_name : str
         The name of the op.
 
-    compute : function
+    compute : function (attrs: Attrs, inputs: List[Tensor], out_type: Type, target:Target)
+                       -> List[Tensor]
         The compute function.
 
     level : int
@@ -133,6 +134,23 @@ def register_compute(op_name, compute=None, level=10):
     return register(op_name, "FTVMCompute", compute, level)
 
 
+def register_alter_op_layout(op_name, alter_layout=None, level=10):
+    """Register alter op layout function for an op
+
+    Parameters
+    ----------
+    op_name : str
+        The name of the operator
+
+    alter_layout: function (attrs: Attrs, inputs: List[Expr]) -> new_expr: Expr
+        The function for changing the layout or replacing the operator
+
+    level : int
+        The priority level
+    """
+    return register(op_name, "FTVMAlterOpLayout", alter_layout, level)
+
+
 def register_pattern(op_name, pattern, level=10):
     """Register operator pattern for an op.
 

python/tvm/relay/op/op_attrs.py

+"""The attributes node used for Relay operators"""
+
+from ...attrs import Attrs
+from ..base import register_relay_attr_node
+
+@register_relay_attr_node
+class Conv2DAttrs(Attrs):
+    """Attribute of a Convolution Operator"""
+    pass
+
+@register_relay_attr_node
+class GlobalPool2DAttrs(Attrs):
+    """Attribute of a Global 2D Pooling Operator"""
+    pass

python/tvm/relay/op/transform.py

@@ -387,3 +387,25 @@ def slice_like(data, shape_like, axes=None):
         The computed result.
     """
     return _make.slice_like(data, shape_like, axes)
+
+
+def layout_transform(data, src_layout, dst_layout):
+    """Transform the layout of a tensor
+
+    Parameters
+    ----------
+    data : relay.Expr
+        The source tensor to be transformed
+
+    src_layout: str
+        The source layout.  (e.g NCHW)
+
+    dst_layout: str
+        The destination layout.  (e.g. NCHW16c)
+
+    Returns
+    -------
+    ret : relay.Expr
+        The transformed tensor.
+    """
+    return _make.layout_transform(data, src_layout, dst_layout)

src/lang/attrs.cc

@@ -3,6 +3,7 @@
  * \file attrs.cc
  */
 #include <tvm/attrs.h>
+#include <tvm/api_registry.h>
 #include "attr_functor.h"
 
 namespace tvm {
@@ -321,4 +322,9 @@ bool DictAttrsNode::ContentEqual(const Node* other, AttrsEqual equal) const {
   return equal(this->dict, static_cast<const DictAttrsNode*>(other)->dict);
 }
 
+TVM_REGISTER_API("_AttrsListFieldInfo")
+.set_body([](TVMArgs args, TVMRetValue* ret) {
+  *ret = args[0].operator Attrs()->ListFieldInfo();
+});
+
 }  // namespace tvm

src/relay/op/layout.h

@@ -185,7 +185,7 @@ class Layout : public NodeRef {
         CHECK_GT(block_size, 0);
         new_layout << block_size;
       }
-      new_layout << layout_simplified[i]->value;
+      new_layout << static_cast<char>(layout_simplified[i]->value);
     }
     return Layout(new_layout.str());
   }
@@ -241,6 +241,16 @@ class Layout : public NodeRef {
     return operator->()->layout_simplified.size();
   }
 
+  /*! \return number of super dimensions */
+  size_t ndim_super() const {
+    size_t ct = 0;
+    for (auto x : operator->()->layout_simplified) {
+      if (IsSuperdim(x))
+        ct++;
+    }
+    return ct;
+  }
+
   /*!
    * \brief The description of the \p i-th dimension.
    *        If it is a sub-dimension, the size will be returned as well,
@@ -327,6 +337,17 @@ class Layout : public NodeRef {
     return operator->()->name == rhs->name;
   }
 
+  /*!
+ * \brief allow output string of layout to ostream
+ * \param os the output stream
+ * \param l the layout
+ * \return the ostream
+ */
+  friend std::ostream& operator<<(std::ostream& os, const Layout& l) {
+    os << l.name();
+    return os;
+  }
+
   using ContainerType = LayoutNode;
 
  private:

src/relay/op/nn/convolution.cc

@@ -7,11 +7,13 @@
 #include <tvm/relay/attrs/nn.h>
 #include <vector>
 
+#include "../../pass/alter_op_layout.h"
 #include "../layout.h"
 
 namespace tvm {
 namespace relay {
 
+// relay.nn.conv2d
 TVM_REGISTER_NODE_TYPE(Conv2DAttrs);
 
 bool Conv2DRel(const Array<Type>& types,
@@ -101,6 +103,20 @@ bool Conv2DRel(const Array<Type>& types,
   return true;
 }
 
+template<typename T>
+Array<Array<Layout> > Conv2DInferCorrectLayout(
+    const Attrs& attrs,
+    const Array<Layout>& new_in_layouts,
+    const Array<Layout>& old_in_layouts,
+    const Array<Array<IndexExpr>> &old_in_shapes) {
+  const T* params = attrs.as<T>();
+  Layout out_layout(params->out_layout);
+
+  // We always make other operators to fit the layouts of convolution layers
+  // So this inference ignores all inputs
+  return Array<Array<Layout> >{{params->data_layout, params->weight_layout},
+                               {out_layout.defined() ? out_layout : params->data_layout}};
+}
 
 // Positional relay function to create conv2d operator
 // used by frontend FFI.
@@ -156,10 +172,11 @@ with the layer input to produce a tensor of outputs.
 .add_argument("data", "Tensor", "The input tensor.")
 .add_argument("weight", "Tensor", "The weight tensor.")
 .set_support_level(2)
-.add_type_rel("Conv2D", Conv2DRel);
+.add_type_rel("Conv2D", Conv2DRel)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout", Conv2DInferCorrectLayout<Conv2DAttrs>);
 
 
-// Conv2DTranspose
+// relay.nn.conv2d_transpose
 TVM_REGISTER_NODE_TYPE(Conv2DTransposeAttrs);
 
 bool Conv2DTransposeRel(const Array<Type>& types,
@@ -185,6 +202,12 @@ bool Conv2DTransposeRel(const Array<Type>& types,
     << "Conv only support kernel layouts that are convertible from OIHW."
     << " But got "<< kernel_layout;
 
+  Layout out_layout(param->out_layout);
+  if (!out_layout.defined()) out_layout = in_layout;
+  CHECK(out_layout.Convertible(kNCHW))
+    << "Conv only support output layouts that are convertible from NCHW."
+    << " But got " << out_layout;
+
   IndexExpr channels, dilated_ksize_y, dilated_ksize_x;
 
   auto dshape_nchw = ConvertLayout(data->shape, in_layout, kNCHW);
@@ -241,7 +264,7 @@ bool Conv2DTransposeRel(const Array<Type>& types,
   if (out_dtype.bits() == 0) {
     out_dtype = data->dtype;
   }
-  oshape = ConvertLayout(oshape, kNCHW, in_layout);
+  oshape = ConvertLayout(oshape, kNCHW, out_layout);
   reporter->Assign(types[2], TensorTypeNode::make(oshape, out_dtype));
   return true;
 }
@@ -307,6 +330,8 @@ v            (batch_size, channels, out_height, out_width) if `layout` is `NCHW`
 .add_argument("data", "Tensor", "The input tensor.")
 .add_argument("weight", "Tensor", "The weight tensor.")
 .set_support_level(2)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout",
+                               Conv2DInferCorrectLayout<Conv2DTransposeAttrs>)
 .add_type_rel("Conv2DTranspose", Conv2DTransposeRel);
 
 }  // namespace relay

src/relay/op/nn/nn.cc

@@ -12,12 +12,14 @@
 #include <topi/nn/flatten.h>
 #include <vector>
 #include "../type_relations.h"
+#include "../../pass/alter_op_layout.h"
 #include "../op_common.h"
 #include "../layout.h"
 
 namespace tvm {
 namespace relay {
 
+// relay.nn.bias_add
 TVM_REGISTER_NODE_TYPE(BiasAddAttrs);
 
 bool BiasAddRel(const Array<Type>& types,
@@ -74,6 +76,7 @@ RELAY_REGISTER_OP("nn.bias_add")
 .add_type_rel("BiasAdd", BiasAddRel);
 
 
+// relay.nn.dense
 TVM_REGISTER_NODE_TYPE(DenseAttrs);
 
 
@@ -143,6 +146,8 @@ RELAY_REGISTER_OP("nn.dense")
 .set_support_level(1)
 .add_type_rel("Dense", DenseRel);
 
+// relay.leaky_relu
+TVM_REGISTER_NODE_TYPE(LeakyReluAttrs);
 
 // Positional relay function to create leaky relu operator used by frontend FFI.
 Expr MakeLeakyRelu(Expr data,
@@ -171,6 +176,7 @@ RELAY_REGISTER_OP("nn.leaky_relu")
 .add_argument("data", "Tensor", "Input data.")
 .set_support_level(3)
 .add_type_rel("Identity", IdentityRel)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout", ElemwiseArbitraryLayout)
 .set_attr<FTVMCompute>(
   "FTVMCompute", [](const Attrs& attrs,
                     const Array<Tensor>& inputs,
@@ -181,6 +187,7 @@ RELAY_REGISTER_OP("nn.leaky_relu")
 });
 
 
+// relay.prelu
 TVM_REGISTER_NODE_TYPE(PReluAttrs);
 
 bool PReluRel(const Array<Type>& types,
@@ -235,6 +242,7 @@ where :math:`*` is an channelwise multiplication for each sample in the batch.
 .add_argument("alpha", "Tensor", "Input channelwise alpha.")
 .set_support_level(3)
 .add_type_rel("PRelu", PReluRel)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout", ElemwiseArbitraryLayout)
 .set_attr<FTVMCompute>(
   "FTVMCompute", [](const Attrs& attrs,
                     const Array<Tensor>& inputs,
@@ -245,6 +253,9 @@ where :math:`*` is an channelwise multiplication for each sample in the batch.
 });
 
 
+// relay.softmax
+TVM_REGISTER_NODE_TYPE(SoftmaxAttrs);
+
 TVM_REGISTER_API("relay.op.nn._make.softmax")
 .set_body([](const TVMArgs& args, TVMRetValue* rv) {
   auto make_func = [](Expr data, int axis) {
@@ -282,6 +293,7 @@ RELAY_REGISTER_OP("nn.softmax")
 });
 
 
+// relay.nn.log_softmax
 TVM_REGISTER_API("relay.op.nn._make.log_softmax")
 .set_body([](const TVMArgs& args, TVMRetValue* rv) {
   auto make_func = [](Expr data, int axis) {
@@ -321,8 +333,7 @@ RELAY_REGISTER_OP("nn.log_softmax")
 });
 
 
-
-// BatchFlatten
+// relay.nn.batch_flatten
 bool BatchFlattenRel(const Array<Type>& types,
                      int num_inputs,
                      const Attrs& attrs,
@@ -410,6 +421,7 @@ RELAY_REGISTER_OP("nn.relu")
 .add_argument("data", "Tensor", "The input tensor.")
 .set_support_level(1)
 .add_type_rel("Identity", IdentityRel)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout", ElemwiseArbitraryLayout)
 .set_attr<FTVMCompute>("FTVMCompute", [](const Attrs& attrs,
                                          const Array<Tensor>& inputs,
                                          const Type& out_type,
@@ -460,6 +472,7 @@ centered at that value (zero padding is added where necessary).
 .set_num_inputs(1)
 .add_argument("data", "Tensor", "The input tensor.")
 .set_support_level(2)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout", ElemwiseArbitraryLayout)
 .add_type_rel("Identity", IdentityRel);
 
 
@@ -495,6 +508,7 @@ Normalizes along dimension axis using an L2 norm
 .set_num_inputs(1)
 .add_argument("data", "Tensor", "The input tensor.")
 .set_support_level(2)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout", ElemwiseArbitraryLayout)
 .add_type_rel("Identity", IdentityRel);
 
 // Dropout
@@ -538,6 +552,7 @@ The whole array is rescaled by ``1/(1-p)`` to keep the expected sum of the input
 .set_num_inputs(1)
 .add_argument("data", "Tensor", "Input to which dropout will be applied.")
 .set_support_level(1)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout", ElemwiseArbitraryLayout)
 .add_type_rel("Dropout", DropoutRel);
 
 // batch_norm

src/relay/op/nn/pad.cc

-/*!
- *  Copyright (c) 2018 by Contributors
- * \file pad.cc
- * \brief Implementation of operator pad
- */
-#include <tvm/ir_operator.h>
-#include <tvm/relay/op.h>
-#include <tvm/relay/attrs/nn.h>
-#include <vector>
-#include "../layout.h"
-
-namespace tvm {
-namespace relay {
-
-TVM_REGISTER_NODE_TYPE(PadAttrs);
-
-bool PadRel(const Array<Type>& types,
-            int num_inputs,
-            const Attrs& attrs,
-            const TypeReporter& reporter) {
-  CHECK_EQ(types.size(), 2);
-  const auto* data = types[0].as<TensorTypeNode>();
-  if (data == nullptr) return false;
-
-  const PadAttrs* param = attrs.as<PadAttrs>();
-  CHECK(param != nullptr);
-
-  // check that pad widths match lengths
-  CHECK(data->shape.size() == param->pad_width.size())
-    << "There should be as many pad width pairs as shape dimensions "
-    << "but the shape has " << data->shape.size() << " dimensions "
-    << "and there are " << param->pad_width.size() << " pad width pairs.";
-
-  // each pad width element should be a pair of positive integers
-  std::vector<IndexExpr> oshape;
-  for (size_t i = 0; i < param->pad_width.size(); i++) {
-    CHECK(param->pad_width[i].size() == 2)
-      << "Each pad width element should be a pair but at index " << i
-      << " there are " << param->pad_width[i].size() << " elements.";
-
-    auto width1 = as_const_int(param->pad_width[i][0]);
-    auto width2 = as_const_int(param->pad_width[i][1]);
-    CHECK(width1 != nullptr);
-    CHECK(width2 != nullptr);
-
-    CHECK(*width1 >= 0)
-      << "Param width elements should be positive but first pad width at "
-      << "index " << i << " is " << *width1 << ".";
-    CHECK(*width2 >= 0)
-      << "Param width elements should be positive but first pad width at "
-      << "index " << i << " is " << *width2 << ".";
-
-    auto padding = make_const(data->shape[i].type(), *width1 + *width2);
-    oshape.push_back(data->shape[i] + padding);
-  }
-
-  reporter->Assign(types[1], TensorTypeNode::make(Array<IndexExpr>(oshape),
-                                                  data->dtype));
-  return true;
-}
-
-// Handler to create a call to the padding op used by front-end FFI
-Expr MakePad(Expr data, Array<Array<IndexExpr> > pad_width, double pad_value) {
-  auto attrs = make_node<PadAttrs>();
-  attrs->pad_value = pad_value;
-  attrs->pad_width = std::move(pad_width);
-  static const Op& op = Op::Get("nn.pad");
-  return CallNode::make(op, {data}, Attrs(attrs), {});
-}
-
-TVM_REGISTER_API("relay.op.nn._make.pad")
-.set_body([](const TVMArgs& args, TVMRetValue* rv) {
-    runtime::detail::unpack_call<Expr, 3>(MakePad, args, rv);
-  });
-
-RELAY_REGISTER_OP("nn.pad")
-.describe(R"code(Pad for n-D tensor.
-
-)code" TVM_ADD_FILELINE)
-.set_attrs_type_key("relay.attrs.PadAttrs")
-.set_num_inputs(1)
-.add_argument("data", "Tensor", "The input tensor.")
-.set_support_level(2)
-.add_type_rel("Pad", PadRel);
-
-}  // namespace relay
-}  // namespace tvm
+/*!
+ *  Copyright (c) 2018 by Contributors
+ * \file pad.cc
+ * \brief Implementation of operator pad
+ */
+#include <tvm/ir_operator.h>
+#include <tvm/relay/op.h>
+#include <tvm/relay/attrs/nn.h>
+#include <vector>
+#include "../layout.h"
+
+namespace tvm {
+namespace relay {
+
+// relay.nn.pad
+TVM_REGISTER_NODE_TYPE(PadAttrs);
+
+bool PadRel(const Array<Type>& types,
+            int num_inputs,
+            const Attrs& attrs,
+            const TypeReporter& reporter) {
+  CHECK_EQ(types.size(), 2);
+  const auto* data = types[0].as<TensorTypeNode>();
+  if (data == nullptr) return false;
+
+  const PadAttrs* param = attrs.as<PadAttrs>();
+  CHECK(param != nullptr);
+
+  // check that pad widths match lengths
+  CHECK(data->shape.size() == param->pad_width.size())
+    << "There should be as many pad width pairs as shape dimensions "
+    << "but the shape has " << data->shape.size() << " dimensions "
+    << "and there are " << param->pad_width.size() << " pad width pairs.";
+
+  // each pad width element should be a pair of positive integers
+  std::vector<IndexExpr> oshape;
+  for (size_t i = 0; i < param->pad_width.size(); i++) {
+    CHECK(param->pad_width[i].size() == 2)
+      << "Each pad width element should be a pair but at index " << i
+      << " there are " << param->pad_width[i].size() << " elements.";
+
+    auto width1 = as_const_int(param->pad_width[i][0]);
+    auto width2 = as_const_int(param->pad_width[i][1]);
+    CHECK(width1 != nullptr);
+    CHECK(width2 != nullptr);
+
+    CHECK(*width1 >= 0)
+      << "Param width elements should be positive but first pad width at "
+      << "index " << i << " is " << *width1 << ".";
+    CHECK(*width2 >= 0)
+      << "Param width elements should be positive but first pad width at "
+      << "index " << i << " is " << *width2 << ".";
+
+    auto padding = make_const(data->shape[i].type(), *width1 + *width2);
+    oshape.push_back(data->shape[i] + padding);
+  }
+
+  reporter->Assign(types[1], TensorTypeNode::make(Array<IndexExpr>(oshape),
+                                                  data->dtype));
+  return true;
+}
+
+// Handler to create a call to the padding op used by front-end FFI
+Expr MakePad(Expr data, Array<Array<IndexExpr> > pad_width, double pad_value) {
+  auto attrs = make_node<PadAttrs>();
+  attrs->pad_value = pad_value;
+  attrs->pad_width = std::move(pad_width);
+  static const Op& op = Op::Get("nn.pad");
+  return CallNode::make(op, {data}, Attrs(attrs), {});
+}
+
+TVM_REGISTER_API("relay.op.nn._make.pad")
+.set_body([](const TVMArgs& args, TVMRetValue* rv) {
+    runtime::detail::unpack_call<Expr, 3>(MakePad, args, rv);
+  });
+
+RELAY_REGISTER_OP("nn.pad")
+.describe(R"code(Pad for n-D tensor.
+
+)code" TVM_ADD_FILELINE)
+.set_attrs_type_key("relay.attrs.PadAttrs")
+.set_num_inputs(1)
+.add_argument("data", "Tensor", "The input tensor.")
+.set_support_level(2)
+.add_type_rel("Pad", PadRel);
+
+}  // namespace relay
+}  // namespace tvm

src/relay/op/nn/pooling.cc

@@ -9,13 +9,39 @@
 #include <topi/nn/pooling.h>
 #include <vector>
 #include "../layout.h"
+#include "../../pass/alter_op_layout.h"
 
 namespace tvm {
 namespace relay {
 
+// relay.nn.max_pool2d & relay.nn.avg_pool2d
 TVM_REGISTER_NODE_TYPE(MaxPool2DAttrs);
 TVM_REGISTER_NODE_TYPE(AvgPool2DAttrs);
 
+template <typename T>
+Array<Array<Layout> > Pool2DInferCorrectLayout(
+    const Attrs& attrs,
+    const Array<Layout>& new_in_layouts,
+    const Array<Layout>& old_in_layouts,
+    const Array<Array<IndexExpr>> &old_in_shapes) {
+  // NOTE: Discard "const" qualifier here.
+  T *params = const_cast<T*>(attrs.as<T>());
+
+  if (new_in_layouts.defined()) {
+    CHECK_EQ(new_in_layouts.size(), 1);
+
+    Layout raw_layout(params->layout);
+    Layout input = new_in_layouts[0];
+    if (input.Indexof('W') == raw_layout.Indexof('W') &&
+        input.Indexof('H') == raw_layout.Indexof('H') &&
+        !input.Contains('w') && !input.Contains('h')) {
+      params->layout = input.name();  // modify self to follow the input layout
+    }
+  }
+
+  return Array<Array<Layout> >{{params->layout}, {params->layout}};
+}
+
 template <typename AttrType>
 bool Pool2DRel(const Array<Type>& types,
                int num_inputs,
@@ -163,6 +189,7 @@ RELAY_REGISTER_OP("nn.max_pool2d")
 .add_argument("data", "Tensor", "The input tensor.")
 .set_support_level(2)
 .add_type_rel("MaxPool2D", Pool2DRel<MaxPool2DAttrs>)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout", Pool2DInferCorrectLayout<MaxPool2DAttrs>)
 .set_attr<FTVMCompute>("FTVMCompute", Pool2DCompute<MaxPool2DAttrs, topi::nn::kMaxPool>);
 
 
@@ -219,9 +246,10 @@ Average pooling operation for one dimensional data.
 .add_argument("data", "Tensor", "The input tensor.")
 .set_support_level(2)
 .add_type_rel("AvgPool2D", Pool2DRel<AvgPool2DAttrs>)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout", Pool2DInferCorrectLayout<AvgPool2DAttrs>)
 .set_attr<FTVMCompute>("FTVMCompute", Pool2DCompute<AvgPool2DAttrs, topi::nn::kAvgPool>);
 
-// Global Pool
+// relay.nn.global_pool_2d & relay.nn.max_pool_2d
 TVM_REGISTER_NODE_TYPE(GlobalPool2DAttrs);
 
 bool GlobalPool2DRel(const Array<Type>& types,
@@ -247,8 +275,9 @@ bool GlobalPool2DRel(const Array<Type>& types,
 
   const auto hidx = layout.Indexof('H');
   const auto widx = layout.Indexof('W');
-  std::vector<IndexExpr> oshape({dshape[0], dshape[1], dshape[2], dshape[3]});
-  oshape[hidx] = oshape[widx] = 1;
+  Array<IndexExpr> oshape(dshape);
+  oshape.Set(hidx, 1);
+  oshape.Set(widx, 1);
 
   // assign output type
   reporter->Assign(types[1], TensorTypeNode::make(oshape, data->dtype));
@@ -307,6 +336,8 @@ RELAY_REGISTER_OP("nn.global_avg_pool2d")
 .add_argument("data", "Tensor", "The input tensor.")
 .set_support_level(2)
 .add_type_rel("GlobalAvgPool2D", GlobalPool2DRel)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout",
+                               Pool2DInferCorrectLayout<GlobalPool2DAttrs>)
 .set_attr<FTVMCompute>("FTVMCompute", GlobalPool2DCompute<topi::nn::kAvgPool>);
 
 // GlobalMaxPool
@@ -338,6 +369,8 @@ RELAY_REGISTER_OP("nn.global_max_pool2d")
 .add_argument("data", "Tensor", "The input tensor.")
 .set_support_level(2)
 .add_type_rel("GlobalMaxPool2D", GlobalPool2DRel)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout",
+                               Pool2DInferCorrectLayout<GlobalPool2DAttrs>)
 .set_attr<FTVMCompute>("FTVMCompute", GlobalPool2DCompute<topi::nn::kMaxPool>);
 
 }  // namespace relay

src/relay/op/op_common.h

@@ -11,6 +11,7 @@
 #include <tvm/relay/op.h>
 #include <tvm/relay/op_attr_types.h>
 #include <vector>
+#include "../pass/alter_op_layout.h"
 
 namespace tvm {
 namespace relay {
@@ -32,21 +33,24 @@ inline std::vector<T> AsVector(const Array<T> &array) {
  * We make the decision to always only expose positional argument.
  * We will do rewrapping in the frontend to support language
  * sugars such as keyword arguments and default value.
- *
- * \param Prefix the prefix of the registry, for example, "relay.op._make.".
- *
+
  * \param OpName the name of registry.
  */
-#define RELAY_REGISTER_UNARY_OP(Prefix, OpName)           \
-  TVM_REGISTER_API(Prefix OpName)                         \
-    .set_body_typed<Expr(Expr)>([](Expr data) {           \
-        static const Op& op = Op::Get(OpName);            \
-        return CallNode::make(op, {data}, Attrs(), {});   \
-      });                                                 \
-  RELAY_REGISTER_OP(OpName)                               \
-    .set_num_inputs(1)                                    \
-    .add_argument("data", "Tensor", "The input tensor.")  \
-    .set_attr<TOpPattern>("TOpPattern", kElemWise)
+#define RELAY_REGISTER_UNARY_OP(OpName)                     \
+  TVM_REGISTER_API("relay.op._make." OpName)                \
+    .set_body_typed<Expr(Expr)>([](Expr data) {             \
+        static const Op& op = Op::Get(OpName);              \
+        return CallNode::make(op, {data}, Attrs(), {});     \
+      });                                                   \
+  RELAY_REGISTER_OP(OpName)                                 \
+    .set_num_inputs(1)                                      \
+    .add_argument("data", "Tensor", "The input tensor.")    \
+    .add_type_rel("Identity", IdentityRel)                  \
+    .set_attr<TOpPattern>("TOpPattern", kElemWise)          \
+    .set_attr<TOpIsStateful>("TOpIsStateful", false)        \
+    .set_attr<FInferCorrectLayout>("FInferCorrectLayout",   \
+                                   ElemwiseArbitraryLayout) \
+
 
 /*! Quick helper macro
  * - Expose a positional make function to construct the node.
@@ -56,12 +60,10 @@ inline std::vector<T> AsVector(const Array<T> &array) {
  * We will do rewrapping in the frontend to support language
  * sugars such as keyword arguments and default value.
  *
- * \param Prefix the prefix of the registry, for example, "relay.op._make.".
- *
  * \param OpName the name of registry.
  */
-#define RELAY_REGISTER_BINARY_OP(Prefix, OpName)                  \
-  TVM_REGISTER_API(Prefix OpName)                                 \
+#define RELAY_REGISTER_BINARY_OP(OpName)                          \
+  TVM_REGISTER_API("relay.op._make." OpName)                      \
     .set_body_typed<Expr(Expr, Expr)>([](Expr lhs, Expr rhs) {    \
         static const Op& op = Op::Get(OpName);                    \
         return CallNode::make(op, {lhs, rhs}, Attrs(), {});       \
@@ -72,7 +74,26 @@ inline std::vector<T> AsVector(const Array<T> &array) {
     .add_argument("rhs", "Tensor", "The right hand side tensor.") \
     .add_type_rel("Broadcast", BroadcastRel)                      \
     .set_attr<TOpPattern>("TOpPattern", kBroadcast)               \
-    .set_attr<TOpIsStateful>("TOpIsStateful", false)
+    .set_attr<TOpIsStateful>("TOpIsStateful", false)              \
+    .set_attr<FInferCorrectLayout>("FInferCorrectLayout",         \
+                                   BinaryBroadcastLayout)
+
+// Comparisons
+#define RELAY_REGISTER_CMP_OP(OpName)                             \
+  TVM_REGISTER_API("relay.op._make." OpName)                      \
+  .set_body_typed<Expr(Expr, Expr)>([](Expr lhs, Expr rhs) {      \
+    static const Op& op = Op::Get(OpName);                        \
+    return CallNode::make(op, {lhs, rhs}, Attrs(), {});           \
+  });                                                             \
+  RELAY_REGISTER_OP(OpName)                                       \
+    .set_num_inputs(2)                                            \
+    .add_argument("lhs", "Tensor", "The left hand side tensor.")  \
+    .add_argument("rhs", "Tensor", "The right hand side tensor.") \
+    .add_type_rel("BroadcastComp", BroadcastCompRel)              \
+    .set_attr<TOpPattern>("TOpPattern", kBroadcast)               \
+    .set_attr<TOpIsStateful>("TOpIsStateful", false)              \
+    .set_attr<FInferCorrectLayout>("FInferCorrectLayout",         \
+                                   BinaryBroadcastLayout)
 
 }  // namespace relay
 }  // namespace tvm

src/relay/op/tensor/binary.cc

@@ -23,71 +23,65 @@ namespace relay {
 
 
 // Addition
-RELAY_REGISTER_BINARY_OP("relay.op._make.", "add")
+RELAY_REGISTER_BINARY_OP("add")
 .describe("Elementwise add with with broadcasting")
 .set_support_level(1)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_BINARY_COMPUTE(topi::add));
 
 // Subtraction
-RELAY_REGISTER_BINARY_OP("relay.op._make.", "subtract")
+RELAY_REGISTER_BINARY_OP("subtract")
 .describe("Elementwise substract with broadcasting")
 .set_support_level(1)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_BINARY_COMPUTE(topi::subtract));
 
 // Right shift
-RELAY_REGISTER_BINARY_OP("relay.op._make.", "right_shift")
+RELAY_REGISTER_BINARY_OP("right_shift")
 .describe("Elementwise right shift with broadcasting")
 .set_support_level(4)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_BINARY_COMPUTE(topi::right_shift));
 
-RELAY_REGISTER_BINARY_OP("relay.op._make.", "left_shift")
+
+RELAY_REGISTER_BINARY_OP("left_shift")
 .describe("Elementwise left shift with broadcasting")
 .set_support_level(4)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_BINARY_COMPUTE(topi::left_shift));
 
-RELAY_REGISTER_BINARY_OP("relay.op._make.", "maximum")
+
+RELAY_REGISTER_BINARY_OP("maximum")
 .describe("Elementwise maximum of two tensors with broadcasting")
 .set_support_level(4)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_BINARY_COMPUTE(topi::maximum));
 
-RELAY_REGISTER_BINARY_OP("relay.op._make.", "minimum")
+
+RELAY_REGISTER_BINARY_OP("minimum")
 .describe("Elementwise minimum of two tensors with broadcasting")
 .set_support_level(4)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_BINARY_COMPUTE(topi::minimum));
 
-RELAY_REGISTER_BINARY_OP("relay.op._make.", "divide")
+
+RELAY_REGISTER_BINARY_OP("divide")
 .describe("Elementwise divide with broadcasting")
 .set_support_level(1)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_BINARY_COMPUTE(topi::divide));
 
-RELAY_REGISTER_BINARY_OP("relay.op._make.", "multiply")
+
+RELAY_REGISTER_BINARY_OP("multiply")
 .describe("Elementwise multiply with broadcasting")
 .set_support_level(1)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_BINARY_COMPUTE(topi::multiply));
 
-RELAY_REGISTER_BINARY_OP("relay.op._make.", "power")
+
+RELAY_REGISTER_BINARY_OP("power")
 .describe("Elementwise power with broadcasting")
 .set_support_level(4)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_BINARY_COMPUTE(topi::power));
 
-RELAY_REGISTER_BINARY_OP("relay.op._make.", "mod")
+
+RELAY_REGISTER_BINARY_OP("mod")
 .describe("Elementwise mod with broadcasting")
 .set_support_level(1)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_BINARY_COMPUTE(topi::mod));
 
-// Comparisons
-#define RELAY_REGISTER_CMP_OP(OpName)                               \
-  TVM_REGISTER_API("relay.op._make." OpName)                        \
-  .set_body_typed<Expr(Expr, Expr)>([](Expr lhs, Expr rhs) {        \
-    static const Op& op = Op::Get(OpName);                          \
-    return CallNode::make(op, {lhs, rhs}, Attrs(), {});             \
-  });                                                               \
-  RELAY_REGISTER_OP(OpName)                                         \
-    .set_num_inputs(2)                                              \
-    .add_argument("lhs", "Tensor", "The left hand side tensor.")    \
-    .add_argument("rhs", "Tensor", "The right hand side tensor.")   \
-    .add_type_rel("BroadcastComp", BroadcastCompRel)                \
-    .set_attr<TOpPattern>("TOpPattern", kBroadcast)
 
 RELAY_REGISTER_CMP_OP("equal")
 .describe("Elementwise equal compare with broadcasting")

src/relay/op/tensor/transform.cc

@@ -11,9 +11,12 @@
 #include <topi/elemwise.h>
 #include <topi/broadcast.h>
 #include <topi/reduction.h>
+#include <topi/nn.h>
 #include <vector>
 #include "../op_common.h"
 #include "../../../arithmetic/compute_expr.h"
+#include "../../pass/alter_op_layout.h"
+#include "../layout.h"
 
 namespace tvm {
 namespace relay {
@@ -156,6 +159,7 @@ RELAY_REGISTER_OP("expand_dims")
 .set_attr<FTVMCompute>("FTVMCompute", ExpandDimsCompute)
 .set_attr<TOpPattern>("TOpPattern", kBroadcast);
 
+// relay.concatenate
 TVM_REGISTER_NODE_TYPE(ConcatenateAttrs);
 
 bool ConcatenateRel(const Array<Type>& types,
@@ -201,6 +205,42 @@ bool ConcatenateRel(const Array<Type>& types,
   return true;
 }
 
+Array<Array<Layout>> ConcatenateLayout(
+    const Attrs& attrs,
+    const Array<Layout>& new_in_layouts,
+    const Array<Layout>& old_in_layouts,
+    const Array<Array<IndexExpr>> &old_in_shapes) {
+  const ConcatenateAttrs* param = attrs.as<ConcatenateAttrs>();
+
+  size_t axis = param->axis < 0 ? param->axis + old_in_shapes[0].size() :
+                static_cast<size_t>(param->axis);
+
+  Layout ret;
+  if (new_in_layouts.defined()) {  // this function is called after some operators are alternated.
+    Layout::LayoutDim concate_dim = old_in_layouts[0][axis];
+    for (size_t i = 0; i < new_in_layouts.size(); ++i) {
+      if (new_in_layouts[i].ndim() > axis &&
+          new_in_layouts[i][axis] == concate_dim) {
+        ret = new_in_layouts[i];
+        break;
+      }
+    }
+  } else {  // this function is called on the original correct relay ir
+    for (size_t i = 0; i < old_in_layouts.size(); ++i) {
+      if (old_in_layouts[i].defined()) {
+        ret = old_in_layouts[i];
+        break;
+      }
+    }
+
+    if (ret.ndim() <= axis || Layout::IsSubdim(ret[axis])) {
+      return Array<Array<Layout> > {{Layout::Undef()}, {Layout::Undef()}};
+    }
+  }
+
+  return Array<Array<Layout> > {Array<Layout>(old_in_layouts.size(), ret), {ret}};
+}
+
 Expr MakeConcatenate(Expr data,
                      int axis) {
   auto attrs = make_node<ConcatenateAttrs>();
@@ -226,7 +266,8 @@ RELAY_REGISTER_OP("concatenate")
 .set_num_inputs(1)
 .add_argument("data", "Tensor", "The input list of tensors.")
 .set_support_level(1)
-.add_type_rel("Concatenate", ConcatenateRel);
+.add_type_rel("Concatenate", ConcatenateRel)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout", ConcatenateLayout);
 
 /* relay.transpose */
 TVM_REGISTER_NODE_TYPE(TransposeAttrs);
@@ -323,7 +364,6 @@ RELAY_REGISTER_OP("transpose")
 .set_attr<TOpPattern>("TOpPattern", kInjective);
 
 /* relay.reshape */
-
 TVM_REGISTER_NODE_TYPE(ReshapeAttrs);
 
 bool ReshapeRel(const Array<Type>& types,
@@ -1252,7 +1292,7 @@ Examples::
 .set_attr<TOpPattern>("TOpPattern", kInjective);
 
 
-// Split
+// relay.split
 TVM_REGISTER_NODE_TYPE(SplitAttrs);
 
 bool SplitRel(const Array<Type>& types,
@@ -1367,6 +1407,7 @@ the entries indicate where along axis the array is split.
 .set_attr<TOpPattern>("TOpPattern", kInjective);
 
 
+// relay.slice_like
 TVM_REGISTER_NODE_TYPE(SliceLikeAttrs);
 
 /*!
@@ -1513,5 +1554,104 @@ RELAY_REGISTER_OP("slice_like")
 .set_attr<FTVMCompute>("FTVMCompute", SliceLikeCompute)
 .set_attr<TOpPattern>("TOpPattern", kInjective);
 
+
+// relay.layout_transform
+Array<Tensor> LayoutTransformCompute(const Attrs& attrs,
+                                     const Array<Tensor>& inputs,
+                                     const Type& out_type,
+                                     const Target& target) {
+  const LayoutTransformAttrs *param = attrs.as<LayoutTransformAttrs>();
+  CHECK(param != nullptr);
+
+  Layout src_layout(param->src_layout);
+  Layout dst_layout(param->dst_layout);
+
+  if (src_layout.Equals(dst_layout)) {
+    return Array<Tensor>{ inputs[0] };
+  }
+
+  CHECK(src_layout.defined() && dst_layout.defined())
+    << "cannot convert from/to undefined layout";
+  CHECK(src_layout.Convertible(dst_layout))
+    << "cannot convert from " << param->src_layout << " to " << param->dst_layout;
+
+  const auto& out_shape = ConvertLayout(inputs[0]->shape, src_layout, dst_layout);
+  return Array<Tensor> {
+      topi::layout_transform(inputs[0], out_shape, [&](const Array<tvm::Var>& dst_indices) {
+        std::vector<tvm::Expr> dst_to_src_indices;
+        for (size_t i = 0; i < src_layout.ndim(); ++i) {
+          Layout::LayoutDim src_axis = src_layout[i];
+          int dst_major_pos = dst_layout.Indexof(Layout::ToSuperdim(src_axis));
+          int dst_minor_pos = dst_layout.Indexof(Layout::ToSubdim(src_axis));
+          int32_t src_factor = static_cast<int32_t>(src_layout.Subsizeof(src_axis));
+          int32_t dst_factor = static_cast<int32_t>(dst_layout.Subsizeof(src_axis));
+
+          tvm::Expr src_index(dst_indices[dst_major_pos]);
+          if (dst_minor_pos >= 0) {
+            CHECK_GT(dst_factor, 0);
+            src_index = src_index * dst_factor + dst_indices[dst_minor_pos];
+          }
+          if (Layout::IsSuperdim(src_axis) && src_factor > 0) {
+            src_index = src_index / src_factor;
+          } else if (Layout::IsSubdim(src_axis) && src_factor > 0) {
+            src_index = src_index % src_factor;
+          }
+          dst_to_src_indices.push_back(src_index);
+        }
+        return Array<tvm::Expr>(dst_to_src_indices);
+      })
+  };
+}
+
+bool LayoutTransformRel(const Array<Type>& types,
+                        int num_inputs,
+                        const Attrs& attrs,
+                        const TypeReporter& reporter) {
+  const auto* data = types[0].as<TensorTypeNode>();
+  CHECK(data != nullptr);
+  const LayoutTransformAttrs* params = attrs.as<LayoutTransformAttrs>();
+
+  Layout src_layout(params->src_layout);
+  Layout dst_layout(params->dst_layout);
+
+  CHECK(src_layout.defined() && dst_layout.defined())
+    << "cannot convert from/to undefined layout";
+  CHECK(src_layout.Convertible(dst_layout))
+    << "cannot convert from " << params->src_layout << " to " << params->dst_layout;
+
+  const auto& out_shape = ConvertLayout(data->shape, src_layout, dst_layout);
+  reporter->Assign(types[1], TensorTypeNode::make(out_shape, data->dtype));
+  return true;
+}
+
+Expr MakeLayoutTransform(Expr data,
+                         std::string src_layout,
+                         std::string dst_layout) {
+  auto attrs = make_node<LayoutTransformAttrs>();
+  attrs->src_layout = std::move(src_layout);
+  attrs->dst_layout = std::move(dst_layout);
+  static const Op& op = Op::Get("layout_transform");
+  return CallNode::make(op, {data}, Attrs(attrs), {});
+}
+
+TVM_REGISTER_API("relay.op._make.layout_transform")
+.set_body([](const TVMArgs& args, TVMRetValue* rv) {
+  runtime::detail::unpack_call<Expr, 3>(MakeLayoutTransform, args, rv);
+});
+
+RELAY_REGISTER_OP("layout_transform")
+.describe(R"code(Transform the input data layout.
+
+For transforming from NCHW to N16cHWC, the `__layout_transform__` operator reshapes
+the input array by output[n, c, h, w, C] = data[n, C*16+c, h, w]
+
+)code" TVM_ADD_FILELINE)
+.set_attrs_type_key("relay.attrs.LayoutTransformAttrs")
+.set_num_inputs(1)
+.add_argument("data", "Tensor", "The input tensor.")
+.add_type_rel("layout_transform", LayoutTransformRel)
+.set_support_level(5)
+.set_attr<FTVMCompute>("FTVMCompute", LayoutTransformCompute);
+
 }  // namespace relay
 }  // namespace tvm

src/relay/op/tensor/unary.cc

@@ -22,7 +22,7 @@ namespace relay {
   }                                                     \
 
 
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "log")
+RELAY_REGISTER_UNARY_OP("log")
 .describe(R"code(Returns the log input array, computed element-wise.
 
 .. math::
@@ -30,11 +30,10 @@ RELAY_REGISTER_UNARY_OP("relay.op._make.", "log")
 
 )code" TVM_ADD_FILELINE)
 .set_support_level(1)
-.add_type_rel("Identity", IdentityRel)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::log));
 
 
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "exp")
+RELAY_REGISTER_UNARY_OP("exp")
 .describe(R"code(Returns the exp input array, computed element-wise.
 
 .. math::
@@ -42,36 +41,30 @@ RELAY_REGISTER_UNARY_OP("relay.op._make.", "exp")
 
 )code" TVM_ADD_FILELINE)
 .set_support_level(1)
-.add_type_rel("Identity", IdentityRel)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::exp));
 
-
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "sqrt")
-.describe(R"code(Returns the sqrt input array, computed element-wise.
+RELAY_REGISTER_UNARY_OP("sqrt")
+.describe(R"code(Returns the rsqrt input array, computed element-wise.
 
 .. math::
    sqrt(x)
 
 )code" TVM_ADD_FILELINE)
 .set_support_level(1)
-.add_type_rel("Identity", IdentityRel)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::sqrt));
 
 
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "zeros_like")
+RELAY_REGISTER_UNARY_OP("zeros_like")
 .describe(R"code(Returns an array of zeros, with same type and shape as the input.
 )code" TVM_ADD_FILELINE)
-.set_support_level(1)
-.add_type_rel("Identity", IdentityRel);
+.set_support_level(4);
 
-
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "ones_like")
+RELAY_REGISTER_UNARY_OP("ones_like")
 .describe(R"code(Returns an array of ones, with same type and shape as the input.
 )code" TVM_ADD_FILELINE)
-.set_support_level(1)
-.add_type_rel("Identity", IdentityRel);
+.set_support_level(4);
 
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "sigmoid")
+RELAY_REGISTER_UNARY_OP("sigmoid")
 .describe(R"code(Returns the sigmoid input array, computed element-wise.
 
 .. math::
@@ -79,48 +72,47 @@ RELAY_REGISTER_UNARY_OP("relay.op._make.", "sigmoid")
 
 )code" TVM_ADD_FILELINE)
 .set_support_level(1)
-.add_type_rel("Identity", IdentityRel)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::sigmoid));
 
 
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "copy")
+RELAY_REGISTER_UNARY_OP("copy")
 .describe(R"code(Copy a tensor.
 )code" TVM_ADD_FILELINE)
 .set_support_level(3)
-.add_type_rel("Identity", IdentityRel)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::identity));
 
 // relay.clip
 TVM_REGISTER_NODE_TYPE(ClipAttrs);
 
 TVM_REGISTER_API("relay.op._make.clip")
-  .set_body_typed<Expr(Expr, double, double)>([](Expr a, double a_min, double a_max) {
-      auto attrs = make_node<ClipAttrs>();
-      attrs->a_min = a_min;
-      attrs->a_max = a_max;
-      static const Op& op = Op::Get("clip");
-    return CallNode::make(op, {a}, Attrs(attrs), {});
-  });
+.set_body_typed<Expr(Expr, double, double)>([](Expr a, double a_min, double a_max) {
+    auto attrs = make_node<ClipAttrs>();
+    attrs->a_min = a_min;
+    attrs->a_max = a_max;
+    static const Op& op = Op::Get("clip");
+  return CallNode::make(op, {a}, Attrs(attrs), {});
+});
 
 RELAY_REGISTER_OP("clip")
-  .describe(R"code(Clip tensor values.
-  This function takes a tensor, a minimum value `a_min`, and a maximum value `a_max`, and returns a clipped tensor where all values below `a_min` are set to `a_min` and all values above `a_max` are set to `a_max`. `a_min` and `a_max` are cast to the tensor's dtype.
-  )code" TVM_ADD_FILELINE)
-  .set_num_inputs(1)
-  .add_argument("tensor", "Tensor", "The input tensor.")
-  .set_support_level(3)
-  .add_type_rel("Clip", IdentityRel);
-
+.describe(R"code(Clip tensor values.
+This function takes a tensor, a minimum value `a_min`, and a maximum value `a_max`, and returns a clipped tensor where all values below `a_min` are set to `a_min` and all values above `a_max` are set to `a_max`. `a_min` and `a_max` are cast to the tensor's dtype.
+)code" TVM_ADD_FILELINE)
+.set_num_inputs(1)
+.add_argument("data", "Tensor", "The input tensor.")
+.add_type_rel("Identity", IdentityRel)
+.set_attr<TOpPattern>("TOpPattern", kElemWise)
+.set_attr<TOpIsStateful>("TOpIsStateful", false)
+.set_attr<FInferCorrectLayout>("FInferCorrectLayout", ElemwiseArbitraryLayout)
+.set_support_level(3);
 
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "floor")
+RELAY_REGISTER_UNARY_OP("floor")
 .describe(R"code(Returns the floor of input array, computed element-wise.
 )code" TVM_ADD_FILELINE)
 .set_support_level(3)
-.add_type_rel("Identity", IdentityRel)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::floor));
 
 
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "ceil")
+RELAY_REGISTER_UNARY_OP("ceil")
 .describe(R"code(Returns the ceil of input array, computed element-wise.
 
 .. math::
@@ -128,11 +120,10 @@ RELAY_REGISTER_UNARY_OP("relay.op._make.", "ceil")
 
 )code" TVM_ADD_FILELINE)
 .set_support_level(3)
-.add_type_rel("Identity", IdentityRel)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::ceil));
 
 
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "trunc")
+RELAY_REGISTER_UNARY_OP("trunc")
 .describe(R"code(Returns the trunc of input array, computed element-wise.
 
 .. math::
@@ -140,11 +131,9 @@ RELAY_REGISTER_UNARY_OP("relay.op._make.", "trunc")
 
 )code" TVM_ADD_FILELINE)
 .set_support_level(3)
-.add_type_rel("Identity", IdentityRel)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::trunc));
 
-
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "round")
+RELAY_REGISTER_UNARY_OP("round")
 .describe(R"code(Returns the round of input array, computed element-wise.
 
 .. math::
@@ -152,11 +141,10 @@ RELAY_REGISTER_UNARY_OP("relay.op._make.", "round")
 
 )code" TVM_ADD_FILELINE)
 .set_support_level(3)
-.add_type_rel("Identity", IdentityRel)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::round));
 
 
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "abs")
+RELAY_REGISTER_UNARY_OP("abs")
 .describe(R"code(Returns the abs of input array, computed element-wise.
 
 .. math::
@@ -164,11 +152,10 @@ RELAY_REGISTER_UNARY_OP("relay.op._make.", "abs")
 
 )code" TVM_ADD_FILELINE)
 .set_support_level(3)
-.add_type_rel("Identity", IdentityRel)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::abs));
 
 
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "tanh")
+RELAY_REGISTER_UNARY_OP("tanh")
 .describe(R"code(Returns the tanh of input array, computed element-wise.
 
 .. math::
@@ -176,11 +163,10 @@ RELAY_REGISTER_UNARY_OP("relay.op._make.", "tanh")
 
 )code" TVM_ADD_FILELINE)
 .set_support_level(1)
-.add_type_rel("Identity", IdentityRel)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::tanh));
 
 
-RELAY_REGISTER_UNARY_OP("relay.op._make.", "negative")
+RELAY_REGISTER_UNARY_OP("negative")
 .describe(R"code(Returns the numeric negative of input array, computed element-wise.
 
 .. math::
@@ -188,7 +174,6 @@ RELAY_REGISTER_UNARY_OP("relay.op._make.", "negative")
 
 )code" TVM_ADD_FILELINE)
 .set_support_level(3)
-.add_type_rel("Identity", IdentityRel)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::negative));
 
 }  // namespace relay

src/relay/pass/alter_op_layout.h

+/*!
+ *  Copyright (c) 2018 by Contributors
+ * \file alter_op_layout.h
+ * \brief Alternate the layouts of operators or replace primitive operators with
+          other expressions. This pass can be used for computing convolution in
+          custom layouts or other general weight pre-transformation.
+ */
+
+#ifndef TVM_RELAY_PASS_ALTER_OP_LAYOUT_H_
+#define TVM_RELAY_PASS_ALTER_OP_LAYOUT_H_
+
+#include <tvm/relay/expr.h>
+
+#include "../op/layout.h"
+
+namespace tvm {
+namespace relay {
+
+/*!
+ * \brief Infer & correct function of node layout. See \p Layout for layout convention
+ * \param attrs The attribute of the node.
+ * \param new_in_layouts The layouts of input arguments after alter_op_layout.
+ *                       This can be undefined, which means we call this function before alternating
+ *                       any operators.
+ * \param old_in_layouts The layouts of input arguments before alter_op_layout.
+ * \param old_in_shapes The shapes of old input arguments.
+ * \return infered_layout An array of two elements that are inferred input layouts and
+ *                        inferred output layouts.
+ */
+using FInferCorrectLayout = runtime::TypedPackedFunc<
+    Array<Array<Layout>>(const Attrs& attrs,
+                         const Array<Layout>& new_in_layouts,
+                         const Array<Layout>& old_in_layouts,
+                         const Array<Array<IndexExpr>> &old_in_shapes)>;
+
+/*! \brief take arbitrary input layout and copy to output */
+inline Array<Array<Layout> > ElemwiseArbitraryLayout(const Attrs& attrs,
+                                                     const Array<Layout>& new_in_layouts,
+                                                     const Array<Layout>& old_in_layouts,
+                                                     const Array<Array<IndexExpr>> &old_in_shapes) {
+  Layout ret;
+
+  if (new_in_layouts.defined()) {
+    CHECK_GE(new_in_layouts.size(), 1);
+    ret = new_in_layouts[0];
+  } else {
+    for (size_t i = 0; i < old_in_layouts.size(); ++i) {
+      if (old_in_layouts[i].defined()) {
+        ret = old_in_layouts[i];
+        break;
+      }
+    }
+  }
+
+  return Array<Array<Layout> >{Array<Layout>(old_in_layouts.size(), ret), {ret}};
+}
+
+/*! \brief Infer layout for binary broadcast operators */
+inline Array<Array<Layout> > BinaryBroadcastLayout(const Attrs& attrs,
+                                                   const Array<Layout>& new_in_layouts,
+                                                   const Array<Layout>& old_in_layouts,
+                                                   const Array<Array<IndexExpr>> &old_in_shapes) {
+  Array<Layout> layouts;
+
+  if (new_in_layouts.defined()) {
+    layouts.assign(new_in_layouts.begin(), new_in_layouts.end());
+  } else {
+    layouts.assign(old_in_layouts.begin(), old_in_layouts.end());
+  }
+
+  if (!layouts[0].defined() && !layouts[1].defined()) {
+    // both undefined, infer fails
+    return Array<Array<Layout> > {{Layout::Undef()}, {Layout::Undef()}};
+  } else if (!layouts[0].defined() || !layouts[1].defined()) {
+    // only one is defined, use shape information to help infer
+    int defined_idx = layouts[0].defined() ? 0 : 1;
+    int undef_idx = 1 - defined_idx;
+
+    if (old_in_shapes[defined_idx].size() >= old_in_shapes[undef_idx].size()) {
+      layouts.Set(undef_idx,
+                  layouts[defined_idx].Sublayout(
+                      old_in_shapes[defined_idx].size() - old_in_shapes[undef_idx].size(),
+                      old_in_shapes[undef_idx].size()));
+      return Array<Array<Layout> > {layouts, {layouts[defined_idx]}};
+    } else {
+      // only know the tensor with smaller dimensions,
+      // so we cannot infer the final broadcasted output.
+      // fails in this case.
+      return Array<Array<Layout> > {{Layout::Undef()}, {Layout::Undef()}};
+    }
+  } else {
+    // try to broadcast the tensors to the larger dimension
+    int large_idx = layouts[0].ndim_super() >= layouts[1].ndim_super() ? 0 : 1;
+    int small_idx = 1 - large_idx;
+    Layout ret = layouts[large_idx];
+
+    // extract common part
+    size_t i = layouts[large_idx].ndim();
+    for (; i != 0; --i) {
+      auto dim = layouts[large_idx][i-1];
+      if (!layouts[small_idx].Contains(Layout::ToSuperdim(dim))) {
+        break;
+      }
+    }
+
+    Layout common_part = layouts[large_idx].Sublayout(i, layouts[large_idx].ndim() - i);
+    if (!layouts[small_idx].Convertible(common_part)) {  // fail
+      return Array<Array<Layout> > {{Layout::Undef()}, {Layout::Undef()}};
+    }
+
+    layouts.Set(small_idx, common_part);
+    return Array<Array<Layout> > {layouts, {ret}};
+  }
+}
+
+}  //  namespace relay
+}  //  namespace tvm
+
+#endif  // TVM_RELAY_PASS_ALTER_OP_LAYOUT_H_

src/relay/pass/canonicalize_ops.cc

+/*!
+ * Copyright (c) 2018 by Contributors
+ * \file canonicalize_ops.cc
+ * \brief Canonicalize special operators to basic operators.
+    This can simplify latter analysis. (e.g. Expand bias_add to expand_dims and broadcast_add.)
+ */
+#include <tvm/relay/pass.h>
+#include <tvm/relay/expr_functor.h>
+#include <tvm/relay/attrs/nn.h>
+#include "pattern_util.h"
+
+namespace tvm {
+namespace relay {
+
+class BiasAddSimplifier : public ExprMutator {
+ public:
+  Expr VisitExpr_(const CallNode* n) {
+    static const Op& bias_add = Op::Get("nn.bias_add");
+    auto new_n = ExprMutator::VisitExpr_(n);
+    if (n->op.same_as(bias_add)) {
+      Call call = Downcast<Call>(new_n);
+      CHECK_EQ(call->args.size(), 2);
+      const BiasAddAttrs* param = call->attrs.as<BiasAddAttrs>();
+
+      auto ttype = call->args[0]->type_as<TensorTypeNode>();
+      size_t n_dim = ttype->shape.size();
+      Expr expanded_bias = ExpandBiasToMatchAxis(call->args[1], n_dim, {param->axis});
+      Expr ret = Add(call->args[0], expanded_bias);
+      ret->checked_type_ = n->checked_type_;
+      return ret;
+    }
+    return new_n;
+  }
+};
+
+Expr CanonicalizeOps(const Expr& e) {
+  return BiasAddSimplifier().Mutate(e);
+}
+
+TVM_REGISTER_API("relay._ir_pass.canonicalize_ops")
+.set_body([](TVMArgs args, TVMRetValue* ret) {
+*ret = CanonicalizeOps(args[0]);
+});
+
+}  // namespace relay
+}  // namespace tvm

src/relay/pass/fold_scale_axis.cc

@@ -29,11 +29,11 @@ using runtime::TypedPackedFunc;
 // FoldScaleAxis algorithm:
 //
 // The general idea is to transform Expr to tuple of
-// (value, axes, scale), where the final result satiesfies:
+// (value, axes, scale), where the final result satisfies:
 //
 // result = value
 // for i, k in enumerate(axes):
-//    k-ith dimension of result *= i-th dimension of scale
+//    k-th dimension of result *= i-th dimension of scale
 //
 // Then we can propagate this signal along and fold the scale if necessary.
 // However, it is possible that certain scale may never be consumed

src/relay/pass/forward_rewrite.cc

@@ -42,13 +42,20 @@ class TempRealizer : private ExprMutator {
 
 class ForwardRewriter : private ExprMutator {
  public:
-  ForwardRewriter(const OpMap<FForwardRewrite>& rewrite_map,
+  ForwardRewriter(const OpMap<FForwardRewrite>* rewrite_map,
                   std::function<NodeRef(const Call&)> fcontext,
                   std::function<Expr(const Expr&)> fmulti_ref_trigger)
       : rewrite_map_(rewrite_map),
         fcontext_(fcontext),
-        fmulti_ref_trigger_(fmulti_ref_trigger) {
-  }
+        fmulti_ref_trigger_(fmulti_ref_trigger) {}
+
+  ForwardRewriter(const FForwardRewrite* rewrite_func,
+                  std::function<NodeRef(const Call&)> fcontext,
+                  std::function<Expr(const Expr&)> fmulti_ref_trigger)
+      : rewrite_func_(rewrite_func),
+        fcontext_(fcontext),
+        fmulti_ref_trigger_(fmulti_ref_trigger) {}
+
 
   // Transform expression.
   Expr Rewrite(Expr expr) {
@@ -60,8 +67,9 @@ class ForwardRewriter : private ExprMutator {
 
  private:
   // The rewrite rule.
-  const OpMap<FForwardRewrite>& rewrite_map_;
-  // The context.
+  const OpMap<FForwardRewrite>* rewrite_map_{nullptr};
+  const FForwardRewrite* rewrite_func_{nullptr};
+  // The context.const
   std::function<NodeRef(const Call&)> fcontext_{nullptr};
   // The multiple reference trigger
   std::function<Expr(const Expr&)> fmulti_ref_trigger_{nullptr};
@@ -104,9 +112,31 @@ class ForwardRewriter : private ExprMutator {
     }
   }
 
+  Expr VisitExpr_(const TupleNode* op) final {
+    tvm::Array<Expr> fields;
+    bool all_fields_unchanged = true;
+    for (auto field : op->fields) {
+      auto new_field = this->GetTempExpr(field);
+      fields.push_back(new_field);
+      all_fields_unchanged &= new_field.same_as(field);
+    }
+
+    if (all_fields_unchanged) {
+      return GetRef<Expr>(op);
+    } else {
+      return TupleNode::make(fields);
+    }
+  }
+
   Expr VisitExpr_(const CallNode* call_node) final {
     const Call& ref_call = GetRef<Call>(call_node);
-    PackedFunc frewrite = rewrite_map_.get(call_node->op, nullptr);
+    PackedFunc frewrite;
+    if (rewrite_func_) {
+      frewrite = *rewrite_func_;
+    } else {
+      CHECK(rewrite_map_);
+      frewrite = rewrite_map_->get(call_node->op, nullptr);
+    }
 
     auto new_op = this->Mutate(call_node->op);
     bool unchanged = call_node->op.same_as(new_op);
@@ -147,9 +177,16 @@ Expr ForwardRewrite(const Expr& expr,
                     std::function<NodeRef(const Call&)> fcontext,
                     std::function<Expr(const Expr&)> fmulti_ref_trigger) {
   auto rewrite_map = Op::GetAttr<FForwardRewrite>(rewrite_map_name);
-  return ForwardRewriter(rewrite_map,
-                         fcontext,
-                         fmulti_ref_trigger).Rewrite(expr);
+  return ForwardRewriter(&rewrite_map, fcontext, fmulti_ref_trigger).Rewrite(expr);
+}
+
+Expr ForwardRewrite(const Expr& expr,
+                    const FForwardRewrite& rewrite_func,
+                    std::function<NodeRef(const Call&)> fcontext,
+                    std::function<Expr(const Expr&)> fmulti_ref_trigger) {
+  return ForwardRewriter(&rewrite_func, fcontext, fmulti_ref_trigger).Rewrite(expr);
 }
+
+
 }  // namespace relay
 }  // namespace tvm

src/relay/pass/pattern_util.h

@@ -73,7 +73,7 @@ inline bool MatchBroadcastToLeftAxes(const TensorTypeNode* tlhs,
  * the target Tensor on the specified axis via broadcasting rule.
  *
  * \param bias The bias.
- * \param target_ndim target dimension.
+ * \param target_ndim Target dimension.
  * \param axes The axis on the output we want to match on.
  */
 inline Expr ExpandBiasToMatchAxis(Expr bias,

topi/include/topi/nn.h

@@ -448,6 +448,7 @@ inline tvm::Tensor group_conv2d_ngchw(const tvm::Tensor& I,
 }
 
 using FLayoutIndicesTransform = std::function<Array<Expr>(const Array<Var>& indices)>;
+
 /*!
  * \brief Transform the layout according to the mapping function \p to_src_indices.
  * \param src the source input.