[REFACTOR][IR] Unified IR IRModule structure.

This PR brings relay::Module as the unified IRModule structure.
IRModule will be used as the basic unit for transformations
through out the stack.

- Rename relay::Module -> IRModule
- Move relay/module.h -> ir/module.h
- ModuleNode::FromExpr -> IRModule::FromExpr
- FromText -> IRModule::FromText

docs/dev/relay_pass_infra.rst

@@ -353,7 +353,7 @@ registration.
     auto fx = relay::FunctionNode::make(tvm::Array<relay::Var>{ y }, call, relay::Type(), {});
 
     // Create a module for optimization.
-    auto mod = relay::ModuleNode::FromExpr(fx);
+    auto mod = IRModule::FromExpr(fx);
 
     // Create a sequential pass.
     tvm::Array<relay::transform::Pass> pass_seqs{

include/tvm/relay/module.h → include/tvm/ir/module.h

@@ -18,55 +18,41 @@
  */
 
 /*!
- * \file tvm/relay/module.h
- * \brief The global environment: contains information needed to
- * compile & optimize Relay programs.
+ * \file tvm/ir/module.h
+ * \brief IRModule that holds the functions and type definitions.
  */
-#ifndef TVM_RELAY_MODULE_H_
-#define TVM_RELAY_MODULE_H_
-
-#include <tvm/relay/error.h>
-#include <tvm/relay/expr.h>
-#include <tvm/relay/adt.h>
-#include <tvm/relay/op.h>
-#include <tvm/relay/type.h>
+#ifndef TVM_IR_MODULE_H_
+#define TVM_IR_MODULE_H_
+
+#include <tvm/ir/type.h>
+#include <tvm/ir/expr.h>
+#include <tvm/ir/adt.h>
+
 #include <string>
 #include <vector>
 #include <unordered_map>
 #include <unordered_set>
 
 namespace tvm {
-namespace relay {
-
-struct Module;
-
-/*! \brief The global environment of Relay programs.
- *
- *  The global environment contains the global
- *  information needed to compile a Relay program.
- *
- *  It contains all global functions, and configuration
- *  options.
+class IRModule;
+/*!
+ * \brief IRModule that holds functions and type definitions.
  *
- *  Many operations require access to the global
- *  Module. We pass the Module by value
- *  in a functional style as an explicit argument,
- *  but we mutate the Module while optimizing
- *  Relay programs.
+ *  IRModule is the basic unit for all IR transformations across the stack.
  *
- *  The functional style allows users to construct custom
- *  environments easily, for example each thread can store
- *  a Module while auto-tuning.
+ *  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 ModuleNode : public RelayNode {
+class IRModuleNode : public Object {
  public:
   /*! \brief A map from ids to all global functions. */
   tvm::Map<GlobalVar, BaseFunc> functions;
   /*! \brief A map from global type vars to ADT type data. */
   tvm::Map<GlobalTypeVar, TypeData> type_definitions;
 
-  ModuleNode() {}
+  IRModuleNode() {}
 
   void VisitAttrs(tvm::AttrVisitor* v) {
     v->Visit("functions", &functions);
@@ -75,10 +61,6 @@ class ModuleNode : public RelayNode {
     v->Visit("global_type_var_map_", &global_type_var_map_);
   }
 
-  TVM_DLL static Module make(tvm::Map<GlobalVar, BaseFunc> global_funcs,
-                             tvm::Map<GlobalTypeVar, TypeData> global_type_defs,
-                             std::unordered_set<std::string> imports = {});
-
   /*!
    * \brief Add a function to the global environment.
    * \param var The var of the global function.
@@ -219,7 +201,7 @@ class ModuleNode : public RelayNode {
    *        functions in another environment.
    * \param other The other environment.
    */
-  TVM_DLL void Update(const Module& other);
+  TVM_DLL void Update(const IRModule& other);
 
   /*!
    * \brief Import Relay code from the file at path.
@@ -243,24 +225,8 @@ class ModuleNode : public RelayNode {
    */
   TVM_DLL std::unordered_set<std::string> Imports() const;
 
-  /*! \brief Construct a module from a standalone expression.
-   *
-   * Allows one to optionally pass a global function map and
-   * map of type definitions as well.
-   *
-   * \param expr The expression to set as the main function to the module.
-   * \param global_funcs The global function map.
-   * \param type_definitions Map of global type definitions
-   *
-   * \returns A module with expr set as the main function.
-   */
-  TVM_DLL static Module FromExpr(
-    const Expr& expr,
-    const tvm::Map<GlobalVar, BaseFunc>& global_funcs = {},
-    const tvm::Map<GlobalTypeVar, TypeData>& type_definitions = {});
-
   static constexpr const char* _type_key = "relay.Module";
-  TVM_DECLARE_FINAL_OBJECT_INFO(ModuleNode, Object);
+  TVM_DECLARE_FINAL_OBJECT_INFO(IRModuleNode, Object);
 
  private:
   /*! \brief Helper function for registering a typedef's constructors */
@@ -285,27 +251,62 @@ class ModuleNode : public RelayNode {
       importing is idempotent for each module.
    */
   std::unordered_set<std::string> import_set_;
+  friend class IRModule;
 };
 
-struct Module : public ObjectRef {
-  Module() {}
-  explicit Module(ObjectPtr<::tvm::Object> p) : ObjectRef(p) {}
-
-  ModuleNode* operator->() const {
-    return static_cast<ModuleNode*>(get_mutable());
+/*!
+ * \brief Managed reference class to IRModuleNode.
+ * \sa IRModuleNode
+ */
+class IRModule : public ObjectRef {
+ public:
+  /*!
+   * \brief constructor
+   * \param functions Functions in the module.
+   * \param type_definitions Type definitions in the module.
+   * \param import_set Set of imported files in the module
+   */
+  TVM_DLL explicit IRModule(tvm::Map<GlobalVar, BaseFunc> functions,
+                            tvm::Map<GlobalTypeVar, TypeData> type_definitions = {},
+                            std::unordered_set<std::string> import_set = {});
+  /*! \brief default constructor */
+  IRModule() {}
+  /*!
+   * \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();
+    CHECK(ptr != nullptr);
+    return static_cast<IRModuleNode*>(ptr);
   }
+  /*!
+   * \brief Construct a module from a standalone expression.
+   *
+   * Allows one to optionally pass a global function map and
+   * map of type definitions as well.
+   *
+   * \param expr The expression to set as the main function to the module.
+   * \param global_funcs The global function map.
+   * \param type_definitions Map of global type definitions
+   *
+   * \returns A module with expr set as the main function.
+   */
+  TVM_DLL static IRModule FromExpr(
+    const RelayExpr& expr,
+    const tvm::Map<GlobalVar, BaseFunc>& global_funcs = {},
+    const tvm::Map<GlobalTypeVar, TypeData>& type_definitions = {});
 
-  using ContainerType = ModuleNode;
+  /*!
+   * \brief Parse text format source file into an IRModule.
+   * \param text A string of Relay source code.
+   * \param source_path The path to the source file.
+   * \return A Relay module.
+   */
+  TVM_DLL static IRModule FromText(const std::string& text, const std::string& source_path);
 };
 
-/*! \brief Parse Relay source into a module.
- * \param source A string of Relay source code.
- * \param source_name The name of the source file.
- * \return A Relay module.
- */
-Module FromText(const std::string& source, const std::string& source_name);
-
-}  // namespace relay
 }  // namespace tvm
-
-#endif  // TVM_RELAY_MODULE_H_
+#endif  // TVM_IR_MODULE_H_

include/tvm/ir/type_relation.h

@@ -30,9 +30,8 @@
 namespace tvm {
 
 // TODO(tqchen): remove after migrate Module to ir.
-namespace relay {
-struct Module;
-}
+class IRModule;
+
 
 /*!
  * \brief reporter that reports back to the
@@ -76,7 +75,7 @@ class TypeReporterNode : public Object {
    * \brief Retrieve the current global module.
    * \return The global module.
    */
-  TVM_DLL virtual relay::Module GetModule() = 0;
+  TVM_DLL virtual IRModule GetModule() = 0;
 
   // solver is not serializable.
   void VisitAttrs(tvm::AttrVisitor* v) {}

include/tvm/ir_pass.h

@@ -71,7 +71,7 @@ Stmt CanonicalSimplify(Stmt stmt,
  * \return Canonicalized expression.
  */
 TVM_DLL PrimExpr CanonicalSimplify(PrimExpr expr,
-                              Map<Var, Range> vrange = Map<Var, Range>());
+                                   Map<Var, Range> vrange = Map<Var, Range>());
 
 /*!
  * \brief Deep compare lhs and rhs

include/tvm/relay/analysis.h

@@ -26,7 +26,7 @@
 
 #include <tvm/relay/adt.h>
 #include <tvm/relay/expr.h>
-#include <tvm/relay/module.h>
+#include <tvm/ir/module.h>
 #include <tvm/relay/type.h>
 #include <string>
 
@@ -49,7 +49,7 @@ namespace relay {
  *
  * \return The kind of the passed type.
  */
-TVM_DLL Kind KindCheck(const Type& t, const Module& mod);
+TVM_DLL Kind KindCheck(const Type& t, const IRModule& mod);
 
 /*!
  * \brief Check whether an expression is constant.
@@ -188,7 +188,7 @@ TVM_DLL tvm::Array<Var> AllVars(const Expr& expr);
  *
  * \return List of free vars, in the PostDFS order visited by expr.
  */
-TVM_DLL tvm::Array<TypeVar> FreeTypeVars(const Expr& expr, const Module& mod);
+TVM_DLL tvm::Array<TypeVar> FreeTypeVars(const Expr& expr, const IRModule& mod);
 
 /*!
  * \brief Get free TypeVars from type t.
@@ -201,7 +201,7 @@ TVM_DLL tvm::Array<TypeVar> FreeTypeVars(const Expr& expr, const Module& mod);
  *
  * \return List of free type vars, in the PostDFS order visited by type.
  */
-TVM_DLL tvm::Array<TypeVar> FreeTypeVars(const Type& t, const Module& mod);
+TVM_DLL tvm::Array<TypeVar> FreeTypeVars(const Type& t, const IRModule& mod);
 
 /*!
  * \brief Get all bound type variables from expression expr.
@@ -214,7 +214,7 @@ TVM_DLL tvm::Array<TypeVar> FreeTypeVars(const Type& t, const Module& mod);
  *
  * \return List of bound type vars, in the PostDFS order in the expression.
  */
-TVM_DLL tvm::Array<TypeVar> BoundTypeVars(const Expr& expr, const Module& mod);
+TVM_DLL tvm::Array<TypeVar> BoundTypeVars(const Expr& expr, const IRModule& mod);
 
 /*!
  * \brief Get all bound type variables from type t.
@@ -227,7 +227,7 @@ TVM_DLL tvm::Array<TypeVar> BoundTypeVars(const Expr& expr, const Module& mod);
  *
  * \return List of bound type vars, in the PostDFS order visited by type.
  */
-TVM_DLL tvm::Array<TypeVar> BoundTypeVars(const Type& t, const Module& mod);
+TVM_DLL tvm::Array<TypeVar> BoundTypeVars(const Type& t, const IRModule& mod);
 
 /*!
  * \brief Get all type variables in expression expr.
@@ -237,7 +237,7 @@ TVM_DLL tvm::Array<TypeVar> BoundTypeVars(const Type& t, const Module& mod);
  *
  * \return List of type vars, in the PostDFS order in the expression.
  */
-TVM_DLL tvm::Array<TypeVar> AllTypeVars(const Expr& expr, const Module& mod);
+TVM_DLL tvm::Array<TypeVar> AllTypeVars(const Expr& expr, const IRModule& mod);
 
 /*!
  * \brief Get all type variables in type t.
@@ -247,7 +247,7 @@ TVM_DLL tvm::Array<TypeVar> AllTypeVars(const Expr& expr, const Module& mod);
  *
  * \return List of type vars, in the PostDFS order visited by type.
  */
-TVM_DLL tvm::Array<TypeVar> AllTypeVars(const Type& t, const Module& mod);
+TVM_DLL tvm::Array<TypeVar> AllTypeVars(const Type& t, const IRModule& mod);
 
 /*!
  * \brief Collect the device mapping information of each expression.
@@ -277,7 +277,7 @@ TVM_DLL Map<Expr, Integer> CollectDeviceAnnotationOps(const Expr& expr);
  * \return Returns a list of cases (as patterns) that are not handled by the match
  * expression.
  */
-TVM_DLL Array<Pattern> UnmatchedCases(const Match& match, const Module& mod);
+TVM_DLL Array<Pattern> UnmatchedCases(const Match& match, const IRModule& mod);
 
 /*! \brief A hashing structure in the style of std::hash. */
 struct StructuralHash {

include/tvm/relay/base.h

@@ -106,9 +106,6 @@ class Id : public ObjectRef {
   TVM_DEFINE_OBJECT_REF_METHODS(Id, ObjectRef, IdNode);
 };
 
-
-struct Module;
-
 }  // namespace relay
 }  // namespace tvm
 

include/tvm/relay/error.h

@@ -24,13 +24,16 @@
 #ifndef TVM_RELAY_ERROR_H_
 #define TVM_RELAY_ERROR_H_
 
+#include <tvm/ir/module.h>
+
 #include <string>
 #include <vector>
 #include <sstream>
 #include <unordered_map>
+
 #include "./base.h"
 #include "./expr.h"
-#include "./module.h"
+
 
 namespace tvm {
 namespace relay {
@@ -146,7 +149,7 @@ class ErrorReporter {
    * \param module The module to report errors on.
    * \param use_color Controls whether to colorize the output.
    */
-  void RenderErrors(const Module& module, bool use_color = true);
+  void RenderErrors(const IRModule& module, bool use_color = true);
 
   inline bool AnyErrors() {
     return errors_.size() != 0;

include/tvm/relay/feature.h

@@ -26,6 +26,8 @@
 
 #include <tvm/node/container.h>
 #include <tvm/relay/expr.h>
+#include <tvm/ir/module.h>
+
 #include <bitset>
 
 namespace tvm {
@@ -141,15 +143,14 @@ class FeatureSet {
  */
 FeatureSet DetectFeature(const RelayExpr& expr);
 
-struct Module;
 /*!
  * \brief Calculate the feature of the program.
  *
  * \param mod The module.
  *
  * \return The FeatureSet.
  */
-FeatureSet DetectFeature(const Module& mod);
+FeatureSet DetectFeature(const IRModule& mod);
 
 /*!
  * \brief Calculate the feature of the program.
@@ -159,7 +160,7 @@ FeatureSet DetectFeature(const Module& mod);
  *
  * \return The FeatureSet.
  */
-inline FeatureSet DetectFeature(const Expr& expr, const Module& mod) {
+inline FeatureSet DetectFeature(const Expr& expr, const IRModule& mod) {
   return DetectFeature(expr) + DetectFeature(mod);
 }