[REFACTOR][ARCH] Introduce StructInfo M0 (apache#314)

* [IR] Introduce StructInfo

* StructInfoFunctor and Analysis Support

* [TVMScript] Parse type/shape annotation with StructInfo

* remove runtime type assign

* Remove type/shape during parsing (apache#2)

* Normalizer prep: simple checks and legacy function renaming.

* Struct info deduction in BlockBuilder.

* Two TODOs

* StructInfo Normalizer Fixes (apache#3)

* StructInfo AST Fix

* Fix Extern Func Deduction and shape mutator.

* Update VoidStructInfo & globalvar (apache#4)

* Fix passes and proper sinfo propagation.

* Refactor EraseToWellDefined to Enable Remapping

* [WIP] First stab at symbolic param tracking

* Update EraseToWellDefined to support symbolic shape return (apache#5)

* fix R.shape with ndim (apache#6)

* Remove update shape/type

* Address review comment, AnnotateTypeShape=>AnnotateStructInfo

* Update include/tvm/script/ir_builder/relax/frame.h

Co-authored-by: Ruihang Lai <ruihangl@cs.cmu.edu>

* Address comments

* Update printer to use structinfo (apache#7)

* Update Error mechanism to prep for obj loc based reporting

* Symbolic shape aware function call return value derivation.

The main flow works as follows:
- Match and populate shape_var_map and var_map by visit each pair of
  param and call arguments.
- Call EraseToWellDefined to map the ret parameter to new result.

* [ANALYSIS] Refactor well-form to only look at struct info.

* Update comments according to reviews.

* Update include/tvm/relax/struct_info.h

Co-authored-by: Ruihang Lai <ruihangl@cs.cmu.edu>

Co-authored-by: Siyuan Feng <Hzfengsy@sjtu.edu.cn>
Co-authored-by: Tianqi Chen <tqchen>
Co-authored-by: Ruihang Lai <ruihangl@cs.cmu.edu>

include/tvm/ir/diagnostic.h

@@ -58,6 +58,14 @@ class DiagnosticNode : public Object {
   DiagnosticLevel level;
   /*! \brief The span at which to report an error. */
   Span span;
+  /*!
+   * \brief The object location at which to report an error.
+   *
+   * The object loc provides a location when span is not always
+   * available during transformation. The error reporter can
+   * still pick up loc->span if necessary.
+   */
+  ObjectRef loc;
   /*! \brief The diagnostic message. */
   String message;
 
@@ -86,6 +94,18 @@ class Diagnostic : public ObjectRef {
   static DiagnosticBuilder Warning(Span span);
   static DiagnosticBuilder Note(Span span);
   static DiagnosticBuilder Help(Span span);
+  // variants uses object location
+  static DiagnosticBuilder Bug(ObjectRef loc);
+  static DiagnosticBuilder Error(ObjectRef loc);
+  static DiagnosticBuilder Warning(ObjectRef loc);
+  static DiagnosticBuilder Note(ObjectRef loc);
+  static DiagnosticBuilder Help(ObjectRef loc);
+  // variants uses object ptr.
+  static DiagnosticBuilder Bug(const Object* loc);
+  static DiagnosticBuilder Error(const Object* loc);
+  static DiagnosticBuilder Warning(const Object* loc);
+  static DiagnosticBuilder Note(const Object* loc);
+  static DiagnosticBuilder Help(const Object* loc);
 
   TVM_DEFINE_NOTNULLABLE_OBJECT_REF_METHODS(Diagnostic, ObjectRef, DiagnosticNode);
 };
@@ -104,6 +124,11 @@ class DiagnosticBuilder {
   /*! \brief The span of the diagnostic. */
   Span span;
 
+  /*!
+   * \brief The object location at which to report an error.
+   */
+  ObjectRef loc;
+
   template <typename T>
   DiagnosticBuilder& operator<<(const T& val) {  // NOLINT(*)
     stream_ << val;
@@ -117,6 +142,8 @@ class DiagnosticBuilder {
 
   DiagnosticBuilder(DiagnosticLevel level, Span span) : level(level), span(span) {}
 
+  DiagnosticBuilder(DiagnosticLevel level, ObjectRef loc) : level(level), loc(loc) {}
+
   operator Diagnostic() { return Diagnostic(this->level, this->span, this->stream_.str()); }
 
  private:

include/tvm/ir/expr.h

@@ -376,6 +376,13 @@ class RelayExprNode : public BaseExprNode {
    */
   mutable Optional<ObjectRef> shape_ = Optional<ObjectRef>();
 
+  /*!
+   * \brief Stores the result of structure information of the
+   *        expression that encapsulate both static shape and
+   *        runtime information such as shape.
+   */
+  mutable Optional<ObjectRef> struct_info_ = Optional<ObjectRef>();
+
   /*!
    * \return The checked_type
    */
@@ -471,6 +478,7 @@ class GlobalVarNode : public RelayExprNode {
     v->Visit("virtual_device_", &virtual_device_);
     v->Visit("span", &span);
     v->Visit("_checked_type_", &checked_type_);
+    v->Visit("struct_info_", &struct_info_);
   }
 
   bool SEqualReduce(const GlobalVarNode* other, SEqualReducer equal) const {

include/tvm/ir/type.h

@@ -132,7 +132,7 @@ class PrimType : public Type {
    * \brief Constructor
    * \param dtype The corresponding dtype.
    */
-  TVM_DLL explicit PrimType(runtime::DataType dtype);
+  TVM_DLL explicit PrimType(runtime::DataType dtype, Span span = Span());
 
   TVM_DEFINE_OBJECT_REF_METHODS(PrimType, Type, PrimTypeNode);
 };

include/tvm/relax/analysis.h

@@ -19,22 +19,266 @@
 
 /*!
  * \file tvm/relax/analysis.h
- * \brief The set of Relax specific analysis passes.
+ * \brief The set of Relax specific analysis on IR.
  */
 #ifndef TVM_RELAX_ANALYSIS_H_
 #define TVM_RELAX_ANALYSIS_H_
 
+#include <tvm/arith/analyzer.h>
 #include <tvm/ir/diagnostic.h>
 #include <tvm/ir/module.h>
 #include <tvm/relax/expr.h>
+#include <tvm/relax/struct_info.h>
 #include <tvm/relay/op_attr_types.h>
 #include <tvm/tir/function.h>
 
+#include <functional>
 #include <utility>
 
 namespace tvm {
 namespace relax {
+//-----------------------------------
+// Shape expression analysis
+//----------------------------------
+/*!
+ * \brief Can prove the two symbolic shape arrays equals to each other.
+ *
+ * \param lhs The left operand.
+ * \param rhs The right operand.
+ * \param ana The analyzer used for integer analysis.
+ * \return The prove result.
+ *
+ * \note This function does best effort prove, which means
+ *       if result is false, there is still possibility that
+ *       two shapes equals to each other during runtime.
+ */
+TVM_DLL bool CanProveShapeEqual(const Array<PrimExpr>& lhs, const Array<PrimExpr>& rhs,
+                                arith::Analyzer* ana);
+
+/*!
+ * \brief Can prove the two symbolic shape expressions equals to each other.
+ *
+ * \param lhs The left operand.
+ * \param rhs The right operand.
+ * \param ana The analyzer used for integer analysis.
+ *
+ * \note This function does best effort prove, which means
+ *       if result is false, there is still possibility that
+ *       two shapes equals to each other during runtime.
+ */
+TVM_DLL bool CanProveShapeEqual(const Expr& lhs, const Expr& rhs, arith::Analyzer* ana);
+
+//-----------------------------------
+// Foundational StructInfo analysis
+//-----------------------------------
+/*!
+ * \brief Get the corresponding static type from a given struct info.
+ * \param info The struct info.
+ * \return the corresponding static type.
+ */
+TVM_DLL Type GetStaticType(const StructInfo& info);
+
+/*!
+ * \brief Get the corresponding struct info from static type.
+ * \param type The input type
+ * \return the corresponding struct info.
+ */
+TVM_DLL StructInfo StructInfoFromType(const Type& type);
+
+// TODO(relax-team): Remove legacy shape related functionalities after phasing out shape_
+/*!
+ * \brief Get the corresponding struct info from static type.
+ * \param type The input type
+ * \param shape_hint The shape hint
+ * \return the corresponding struct info.
+ */
+TVM_DLL StructInfo StructInfoFromTypeLegacyShapeHint(const Type& type, Optional<Expr> shape_hint);
+
+/*!
+ * \brief Get the corresponding legacy shape hint from struct info
+ * \param info The struct info.
+ * \return the corresponding legacy shape hint.
+ */
+TVM_DLL Optional<Expr> GetLegacyShapeHint(const StructInfo& info);
+
+/*!
+ * \return Derive the call's ret value struct info from inputs.
+ * \param func_info The function struct info.
+ * \param call The call expression to be derived.
+ * \param ctx The builder context.
+ * \param ana Optional context analyzer to prove symbolic expression equality.
+ * \return The derived struct info of the call.
+ * \note  call->op field is ignored during derivation and we only rely on information
+ *        presented by func_sinfo.
+ */
+TVM_DLL StructInfo DeriveCallRetStructInfo(const FuncStructInfo& finfo, const Call& call,
+                                           const BlockBuilder& ctx, arith::Analyzer* ana = nullptr);
+
+/*!
+ * \brief Erase the info to a corresponding more coarse grained
+ *        struct info that is still well-defined(with all the vars in scope).
+ *
+ * When we are returning a StructInfo to another scope,
+ * it is important to remember that StructInfo may carry
+ * dependencies on var that is not defined the other scope.
+ *
+ * In such cases, it is important to call EraseToWellDefined to get
+ * another StructInfo that **only** contains the vars that are defined
+ * in the target scope.
+ *
+ * For example, consider the following function
+ *
+ * \code
+ *
+ * @R.function
+ * def f(x: R.Tensor[(n, m)]):
+ *     k = tir.Var("k", "int64")
+ *     v0 = opaque_fn(x)
+ *     v1 = match_cast(v0, R.Tensor[(n, k)])
+ *     v2 : R.Tensor[(n + 1, k + 2)] = pad(v1)
+ *     return v2
+ *
+ * \endcode
+ *
+ * In the above code, the return value y have shape `(n + 1, k + 2)`,
+ * However, at the level of function signature, only n, m are defined,
+ * k is undefined here.
+ *
+ * When we call EraseToWellDefined(R.Tensor[(n + 1, k + 2)], fshape_var_map={n: n, m: m}),
+ * we will obtain R.Tensor(ndim=2), which is an erased info that does not depend
+ * on k(which is undefined from parameter signature).
+ *
+ * However, if we call EraseToWellDefined(R.Tensor[(n + 1, m)], fshape_var_map={n: n, m: m}),
+ * Then the return value will be R.Tensor[(n + 1, m)], because both n and m are defined.
+ *
+ * We can also make these var map to return a different expression.
+ * For example, EraseToWellDefined(R.Tensor[(n + 1, m)], fshape_var_map={n: 2, m: m})
+ * will give us R.Tensor[(3, m)], where n get replaced by 2.
+ *
+ * Use this function in the following scenarios:
+ * - Decide the struct_info of expr with sub-scopes, such as If, SeqExpr
+ * - Decide the deduced return struct_info of a function that can be fully decided by params.
+ *
+ * \param info The struct info.
+ * \param f_shape_var_map callback function to specify
+ *        whether a symbolic shape var is defined and the value it maps to,
+ *        return nullopt if var is undefined.
+ * \param f_var_defined callback function to specify
+ *        whether a var is defined in the target scope and the value it maps to,
+ *        return nullopt if var is undefined.
+ * \param ana Optional context analyzer to prove symbolic expression equality.
+ *
+ * \return the corresponding erased struct info.
+ */
+TVM_DLL StructInfo
+EraseToWellDefined(const StructInfo& info,
+                   std::function<Optional<PrimExpr>(const tir::Var& var)> f_shape_var_map = nullptr,
+                   std::function<Optional<Expr>(const Var& var)> f_var_map = nullptr,
+                   arith::Analyzer* ana = nullptr);
+
+/*!
+ * \brief EraseToWellDefined variant with map.
+ * \param info The struct info.
+ * \param f_shape_var_map callback function to specify
+ *        whether a symbolic shape var is defined and the value it maps to,
+ *        return nullopt if var is undefined.
+ * \param f_var_defined callback function to specify
+ *        whether a var is defined in the target scope and the value it maps to,
+ *        return nullopt if var is undefined.
+ * \param ana Optional context analyzer to prove symbolic expression equality.
+ *
+ * \return the corresponding erased struct info.
+ */
+TVM_DLL StructInfo EraseToWellDefined(const StructInfo& info, Map<tir::Var, PrimExpr> shape_var_map,
+                                      Map<Var, Expr> var_map, arith::Analyzer* ana = nullptr);
+
+/*!
+ * \brief Fine grained result of base check.
+ *
+ * This analysis comes with different levels of checking failures
+ * that can help to customize the compilation decisions.
+ *
+ * For a given pair of lhs_struct_info, rhs_struct_info. We adopt
+ * the following terminology:
+ * - LSet = {value | value mactches lhs_struct_info}
+ * - RSet = {value | value mactches rhs_struct_info}
+ *
+ * See the definition of each level below.
+ */
+enum class BaseCheckResult {
+  /*!
+   * \brief The two value sets have no intersection at all: Interset(LSet, RSet) = empty
+   */
+  kFailL0 = 0,
+  /*!
+   * \brief LSet is not superset of RSet by only looking at static information.
+   *
+   * \note This level will trigger static type checking error when lhs is param and rhs is arg.
+   */
+  kFailL1 = 1,
+  /*!
+   * \brief WLSet is not superset of RSet because of mismatch in value information.
+   *
+   * L1-level mismatches in params of FuncStructInfo is categorized as
+   * If lhs is FuncStructInfo, then L1-level mismatch in its params
+   * is categorized as L2-level mismatch for lhs.
+   *
+   * Design considerations for functions:
+   * - (a) We want to be able to erase type/value in function signature
+   *       when we unify function struct info and preserve simpler representations.
+   * - (b) We automatically insert match_cast at function boundary, so
+   *       we can erase (int)->int argument as (object)->int.
+   *       The input shape/type mismatch will be detected by runtime checks at function boundary.
+   *       This behavior is also consistent with the PackedFunc behavior.
+   *
+   * \note This level means there is no problem about static known information.
+   *       It is OK for the checker to do best effort and return this value.
+   */
+  kFailL2 = 2,
+  /*! \brief LSet is superset of RSet. */
+  kPass = 3
+};
+
+/*!
+ * \brief Run a base check to see if base subsumes derived.
+ *
+ * This function returns fine-grained base-check result on reasons of failure.
+ *
+ * \param base The base struct info.
+ * \param derived The derived struct info.
+ * \param ana Optional context analyzer to prove symbolic expression equality.
+ * \return Whether the relation holds.
+ *
+ * \sa BaseCheckResult
+ */
+TVM_DLL BaseCheckResult StructInfoBaseCheck(const StructInfo& base, const StructInfo& derived,
+                                            arith::Analyzer* ana = nullptr);
+
+/*!
+ * \brief Check the relation of two struct info to see if one subsumes another one.
+ *
+ * \param base The base struct info.
+ * \param derived The derived struct info.
+ * \param ana Optional context analyzer to prove symbolic expression equality.
+ * \return Whether the relation holds.
+ */
+TVM_DLL bool IsBaseOf(const StructInfo& base, const StructInfo& derived,
+                      arith::Analyzer* ana = nullptr);
+
+/*!
+ * \brief Unify the two struct info their least common ancestor.
+ *
+ * \param lhs The left operand.
+ * \param rhs The right operand.
+ * \param ana Optional context analyzer to prove symbolic expression equality.
+ * \return The unified information.
+ */
+TVM_DLL StructInfo StructInfoLCA(const StructInfo& lhs, const StructInfo& rhs,
+                                 arith::Analyzer* ana = nullptr);
 
+//-----------------------------------
+// General IR analysis
+//----------------------------------
 /*!
  * \brief Check if the IRModule is well formed.
  *