include/tvm/ir/module.h

/*
 * 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/module.h
 * \brief IRModule that holds the functions and type definitions.
 */
#ifndef TVM_IR_MODULE_H_
#define TVM_IR_MODULE_H_

#include <tvm/ir/expr.h>
#include <tvm/ir/function.h>
#include <tvm/ir/global_info.h>
#include <tvm/ir/source_map.h>
#include <tvm/ir/type.h>
#include <tvm/runtime/container/array.h>
#include <tvm/runtime/container/map.h>
#include <tvm/runtime/container/string.h>

#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

namespace tvm {

class IRModule;

/*!
 * \brief IRModule that holds functions and type definitions.
 *
 *  IRModule is the basic unit for all IR transformations across the stack.
 *
 *  Many operations require access to the global IRModule.
 *  We pass the IRModule by value in a functional style as an explicit argument,
 *  but we mutate the Module while optimizing programs.
 * \sa IRModule
 */
class IRModuleNode : public Object {
 public:
  /*! \brief A map from ids to all global functions. */
  Map<GlobalVar, BaseFunc> functions;
  /*! \brief The source map for the module. */
  SourceMap source_map;
  /* \brief Additional attributes storing meta-data about the module. */
  DictAttrs attrs;
  /*! \brief Globally static object that are referred by the IR itself */
  Map<String, Array<GlobalInfo>> global_infos;
  /*!
   * \brief A map from string names to global variables that
   * ensures global uniqueness.
   */
  Map<String, GlobalVar> global_var_map_;

  /*!
   * \brief Get a module attribute.
   *
   * \param attr_key The attribute key.
   * \param default_value The default value if the key does not exist, defaults to nullptr.
   *
   * \return The result
   *
   * \tparam TOBjectRef the expected object type.
   * \throw Error if the key exists but the value does not match TObjectRef
   *
   * \code
   *
   *  void GetAttrExample(const IRModule& mod) {
   *    auto value = f->GetAttr<Integer>("AttrKey", 0);
   *  }
   *
   * \endcode
   */
  template <typename TObjectRef>
  Optional<TObjectRef> GetAttr(
      const std::string& attr_key,
      Optional<TObjectRef> default_value = Optional<TObjectRef>(std::nullopt)) const {
    return attrs.GetAttr(attr_key, default_value);
  }
  // variant that uses TObjectRef to enable implicit conversion to default value.
  template <typename TObjectRef>
  Optional<TObjectRef> GetAttr(const std::string& attr_key, TObjectRef default_value) const {
    return GetAttr<TObjectRef>(attr_key, Optional<TObjectRef>(default_value));
  }

  /*!
   * \brief Get the metadata attributes.
   * \returns The additional meta-data attributes
   */
  DictAttrs GetAttrs() const { return attrs; }

  /*!
   * \brief Check whether the module has an non-zero integer attr.
   *
   * This function can be used to check whether an optional
   * attribute mark(e.g. inline) exists.
   *
   * \param attr_key The key to the attribute.
   * \return The check result.
   *
   * \code
   *
   *  void HasNonzeroAttrExample(const IRModule& mod) {
   *    if (mod->HasNonzeroAttr(attr::kInline)) {
   *      // inline the function.
   *    }
   *  }
   *
   * \endcode
   */
  bool HasNonzeroAttr(const std::string& attr_key) const { return attrs.HasNonzeroAttr(attr_key); }

  IRModuleNode() : source_map() {}

  void VisitAttrs(AttrVisitor* v) {
    v->Visit("functions", &functions);
    v->Visit("global_var_map_", &global_var_map_);
    v->Visit("source_map", &source_map);
    v->Visit("attrs", &attrs);
    v->Visit("global_infos", &global_infos);
  }

  TVM_DLL bool SEqualReduce(const IRModuleNode* other, SEqualReducer equal) const;

  TVM_DLL void SHashReduce(SHashReducer hash_reduce) const;

  /*!
   * \brief Add a function to the global environment.
   * \param var The var of the global function.
   * \param func The function.
   * \param update Controls whether you can replace a definition in the
   * environment.
   */
  TVM_DLL void Add(const GlobalVar& var, const BaseFunc& func, bool update = false);

  /*!
   * \brief Add a function to the global environment.
   * \param var The name of the global function.
   * \param func The function.
   *
   * It does not do type inference as Add does.
   */
  TVM_DLL void AddUnchecked(const GlobalVar& var, const BaseFunc& func);

  /*!
   * \brief Update a function in the global environment.
   * \param var The name of the global function to update.
   * \param func The new function.
   */
  TVM_DLL void Update(const GlobalVar& var, const BaseFunc& func);

  /*!
   * \brief Update an array of global infos in the global environment.
   * \param name The name of the global info.
   * \param info The new array of global infos.
   */
  TVM_DLL void UpdateGlobalInfo(const String& name, const Array<GlobalInfo>& info);

  /*!
   * \brief Remove a function from the global environment.
   * \param var The name of the global function to update.
   */
  TVM_DLL void Remove(const GlobalVar& var);

  /*!
   * \brief Check if the global_var_map_ contains a global variable.
   * \param name The variable name.
   * \returns true if contains, otherise false.
   */
  TVM_DLL bool ContainGlobalVar(const String& name) const;

  /*!
   * \brief Lookup a global function by its variable.
   * \param str The unique string specifying the global variable.
   * \returns The global variable.
   */
  TVM_DLL GlobalVar GetGlobalVar(const String& str) const;

  /*!
   * \brief Collect all global vars defined in this module, ordered by
   *        the global variable name.
   * \returns An array of global vars
   */
  TVM_DLL Array<GlobalVar> GetGlobalVars() const;

  /*!
   * \brief Look up a global function by its variable.
   * \param var The global var to lookup.
   * \returns The function named by the variable argument.
   */
  TVM_DLL BaseFunc Lookup(const GlobalVar& var) const;

  /*!
   * \brief Look up a global function by its string name
   * \param name The name of the function.
   * \returns The function named by the argument.
   */
  TVM_DLL BaseFunc Lookup(const String& name) const;

  /*!
   * \brief Update the functions inside this environment by
   *        functions in another environment.
   * \param other The other environment.
   */
  TVM_DLL void Update(const IRModule& other);

  /*!
   * \brief Create a shallow copy of this IRModule.
   * \returns The shallow copy of the IRModule.
   */
  TVM_DLL IRModule ShallowCopy();
  /*!
   * \brief The set of imported files.
   */
  TVM_DLL std::unordered_set<String> Imports() const;

  TVM_OBJECT_ENABLE_SCRIPT_PRINTER();

  static constexpr const char* _type_key = "IRModule";
  static constexpr const bool _type_has_method_sequal_reduce = true;
  static constexpr const bool _type_has_method_shash_reduce = true;
  TVM_DECLARE_FINAL_OBJECT_INFO(IRModuleNode, Object);

 private:
  friend class IRModule;
};

/*!
 * \brief Managed reference class to IRModuleNode.
 * \sa IRModuleNode
 */
class IRModule : public ObjectRef {
 public:
  /*!
   * \brief constructor
   * \param functions Functions in the module.
   * \param map The module source map.
   * \param attrs The module meta-data attributes.
   * \param global_infos Global infos in the module.
   */
  TVM_DLL explicit IRModule(Map<GlobalVar, BaseFunc> functions, SourceMap map = {},
                            DictAttrs attrs = DictAttrs(),
                            Map<String, Array<GlobalInfo>> global_infos = {});

  /*! \brief default constructor */
  IRModule() : IRModule(Map<GlobalVar, BaseFunc>({})) {}
  /*!
   * \brief constructor
   * \param n The object pointer.
   */
  explicit IRModule(ObjectPtr<Object> n) : ObjectRef(n) {}
  /*! \return mutable pointers to the node. */
  IRModuleNode* operator->() const {
    auto* ptr = get_mutable();
    ICHECK(ptr != nullptr);
    return static_cast<IRModuleNode*>(ptr);
  }

  /*!
   * \brief As for \p FromExprInContext, but assuming \p expr is bound to 'main' and no
   * imports.
   */
  TVM_DLL static IRModule FromExpr(const RelaxExpr& expr,
                                   const Map<GlobalVar, BaseFunc>& global_funcs = {});

  /*!
   * \brief Create a shallow copy of an IRModule.
   * \param mod The module to copy.
   * \return The copied module.
   */
  IRModule ShallowCopyIRModule(IRModule mod);

  /*! \brief Declare the container type. */
  using ContainerType = IRModuleNode;

  // allow copy on write.
  TVM_DEFINE_OBJECT_REF_COW_METHOD(IRModuleNode);
};

namespace attr {

// Following are attributes for IRModule only.

/*!
 * \brief Name of the module
 *
 * Type: String
 */
constexpr const char* kModuleName = "mod_name";

/*
 * \brief All the runtime::NDArrays extracted from PrimFunc tir::AllocateConst nodes. The
 * node will record the index into this array. See also kConstNameToConstant below, which is
 * the analog for Realy Functions.
 *
 * Type: Array<runtime::NDArray>
 */
constexpr const char* kConstants = "constants";

/*!
 * \brief All the runtime::Modules accumulated during compilation by external codegen. These
 * modules must be either directly linked or captured in the final compilation artifact.
 *
 * Type: Array<runtime::Module>
 */
constexpr const char* kExternalMods = "external_mods";

/*!
 * \brief A prefix for generating C symbols  system lib creation.
 *
 * This prefix guides passes that creates global_symbol for internal functions
 * that may have c linkage (e.g. TIR functions and some BYOC functions). It also affects
 * the symbol of the fat bin blob during module export.
 *
 * This attribute is used to avoid symbol conflict when we
 * generate and combine multiple system libs that get linked into one.
 *
 * Rationale: mechanisms like BYOC rely on the common global symbol
 * and each external compiler also has its own mechanism of mangling.
 * As a result, we cannot rely on other mechanisms on setting a global_symbol and then renaming,
 * because the external compiler already agreed on the name.
 *
 * system_lib_prefix provides a way to hint at the passes to allow names to
 * avoid name conflict at the beginning.
 *
 * Note that users can still directly specify global symbols that may conflict.
 * It is up to the downstream toolchain to manage those external-facing functions.
 *
 * This does not affect non-C linkage functions it is less of an issue because
 * they will be embedded into fatbin that in different symbols,
 * The system lib loader can pick the right prefix for a given prefix.
 *
 * Having this attribute implies system lib generation linkage.
 */
constexpr const char* kSystemLibPrefix = "system_lib_prefix";

/*!
 * \brief All the named runtime::NDArrays accumulated during compilation by external codegen.
 * Generally the associated runtime::Module will indicate it requires bindings for these names,
 * and during module initialization these bindings will be recovered from a ConstLoaderModule.
 * See also kConstantsArray above, which is the analog for PrimFuncs.
 *
 * Type: Map<String, runtime::NDArray>
 */
constexpr const char* kConstNameToConstant = "const_name_to_constant";

}  // namespace attr
}  // namespace tvm
#endif  // TVM_IR_MODULE_H_