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apache--tvm/include/tvm/ir/node_functor.h
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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
/*!
* \file tvm/ir/node_functor.h
* \brief Defines the Functor data structures.
*/
#ifndef TVM_IR_NODE_FUNCTOR_H_
#define TVM_IR_NODE_FUNCTOR_H_
#include <tvm/ffi/error.h>
#include <cstring>
#include <type_traits>
#include <utility>
#include <vector>
namespace tvm {
/*!
* \brief A dynamically dispatched functor on the type of the first argument.
*
* This is a class that is useful to construct polymorphic dispatching
* base on the AST/IR node's type.
*
* \code
* NodeFunctor<std::string (const ffi::ObjectRef& n, std::string prefix)> tostr;
* tostr.set_dispatch<Add>([](const ffi::ObjectRef& op, std::string prefix) {
* return prefix + "Add";
* });
* tostr.set_dispatch<IntImm>([](const ffi::ObjectRef& op, std::string prefix) {
* return prefix + "IntImm"
* });
*
* Expr x = MakeConst(1);
* Expr y = x + x;
* // dispatch to IntImm, outputs "MyIntImm"
* LOG(INFO) << tostr(x, "My");
* // dispatch to IntImm, outputs "MyAdd"
* LOG(INFO) << tostr(y, "My");
* \endcode
*
* \tparam FType function signiture
* This type if only defined for FType with function signature
*/
template <typename FType>
class NodeFunctor;
template <typename R, typename... Args>
class NodeFunctor<R(const ffi::ObjectRef& n, Args...)> {
private:
/*! \brief internal function pointer type */
typedef R (*FPointer)(const ffi::ObjectRef& n, Args...);
/*! \brief refer to itself. */
using TSelf = NodeFunctor<R(const ffi::ObjectRef& n, Args...)>;
/*! \brief internal function table */
std::vector<FPointer> func_;
/*! \brief start range of func index */
uint32_t begin_type_index_{0};
public:
/*! \brief the result type of this functor */
using result_type = R;
/*!
* \brief Whether the functor can dispatch the corresponding Node
* \param n The node to be dispatched
* \return Whether dispatching function is registered for n's type.
*/
bool can_dispatch(const ffi::ObjectRef& n) const {
uint32_t type_index = n->type_index();
if (type_index < begin_type_index_) return false;
type_index -= begin_type_index_;
return type_index < func_.size() && func_[type_index] != nullptr;
}
/*!
* \brief invoke the functor, dispatch on type of n
* \param n The Node argument
* \param args The additional arguments
* \return The result.
*/
R operator()(const ffi::ObjectRef& n, Args... args) const {
TVM_FFI_ICHECK(can_dispatch(n))
<< "NodeFunctor calls un-registered function on type " << n->GetTypeKey();
return (*func_[n->type_index() - begin_type_index_])(n, std::forward<Args>(args)...);
}
/*!
* \brief set the dispatcher for type TNode
* \param f The function to be set.
* \tparam TNode the type of Node to be dispatched.
* \return reference to self.
*/
template <typename TNode>
TSelf& set_dispatch(FPointer f) { // NOLINT(*)
uint32_t tindex = TNode::RuntimeTypeIndex();
if (func_.size() <= tindex) {
func_.resize(tindex + 1, nullptr);
}
TVM_FFI_ICHECK(func_[tindex] == nullptr)
<< "Dispatch for " << TNode::_type_key << " is already set";
TVM_FFI_ICHECK_EQ(begin_type_index_, 0) << " Cannot call set_dispatch after calling Finalize";
func_[tindex] = f;
return *this;
}
/*!
* \brief unset the dispatcher for type TNode
*
* \tparam TNode the type of Node to be dispatched.
* \return reference to self.
*/
template <typename TNode>
TSelf& clear_dispatch() { // NOLINT(*)
uint32_t tindex = TNode::RuntimeTypeIndex();
TVM_FFI_ICHECK_LT(tindex, func_.size()) << "clear_dispatch: index out of range";
TVM_FFI_ICHECK_EQ(begin_type_index_, 0) << " Cannot call clear_dispatch after calling Finalize";
func_[tindex] = nullptr;
return *this;
}
/*!
* \brief Finalize the functor after calling sequence of set_dispatch
* This function will attempt to find the min type index that is not null
* and optimize the space of the func table so it is more compact
*/
void Finalize() {
TVM_FFI_ICHECK_EQ(begin_type_index_, 0) << "Can only call Finalize once";
while (begin_type_index_ < func_.size() && func_[begin_type_index_] == nullptr) {
++begin_type_index_;
}
// shift up the function value
size_t new_ftable_size = func_.size() - begin_type_index_;
if (begin_type_index_ != 0) {
std::memmove(func_.data(), func_.data() + begin_type_index_,
new_ftable_size * sizeof(FPointer));
}
func_.resize(new_ftable_size);
func_.shrink_to_fit();
}
};
#define TVM_REG_FUNC_VAR_DEF(ClsName) [[maybe_unused]] static auto& __make_functor##_##ClsName
/*!
* \brief Useful macro to set NodeFunctor dispatch in a global static field.
*
* \code
* // Use NodeFunctor to implement TVMScriptPrinter similar to Visitor Pattern.
* // vtable allows easy patch of new Node types, without changing
* // the interface of TVMScriptPrinter.
*
* class TVMScriptPrinter {
* public:
* // the dispatch function.
* static std::string Script(const ffi::ObjectRef& node, const PrinterConfig& cfg) {
* return vtable()(node, cfg);
* }
* using FType = NodeFunctor<std::string(const ffi::ObjectRef&, const PrinterConfig&)>;
* // function to return global function table
* static FType& vtable();
* };
*
* // in cpp/cc file
* TVMScriptPrinter::FType& TVMScriptPrinter::vtable() {
* static FType inst; return inst;
* }
*
* TVM_STATIC_IR_FUNCTOR(TVMScriptPrinter, vtable)
* .set_dispatch<AddNode>([](const ffi::ObjectRef& ref, const PrinterConfig& cfg) {
* auto* n = static_cast<const AddNode*>(ref.get());
* return Script(n->a, cfg) + " + " + Script(n->b, cfg);
* });
*
* \endcode
*
* \param ClsName The name of the class
* \param FField The static function that returns a singleton of NodeFunctor.
*/
#define TVM_STATIC_IR_FUNCTOR(ClsName, FField) \
TVM_FFI_STR_CONCAT(TVM_REG_FUNC_VAR_DEF(ClsName), __COUNTER__) = ClsName::FField()
} // namespace tvm
#endif // TVM_IR_NODE_FUNCTOR_H_