[Relay] Add generic & informative Relay error reporting (apache#2408)

.gitmodules

@@ -7,3 +7,6 @@
 [submodule "dlpack"]
 	path = 3rdparty/dlpack
 	url = https://github.com/dmlc/dlpack
+[submodule "3rdparty/rang"]
+	path = 3rdparty/rang
+	url = https://github.com/agauniyal/rang

CMakeLists.txt

@@ -84,6 +84,7 @@ tvm_option(USE_ANTLR "Build with ANTLR for Relay parsing" OFF)
 include_directories("include")
 include_directories("3rdparty/dlpack/include")
 include_directories("3rdparty/dmlc-core/include")
+include_directories("3rdparty/rang/include")
 include_directories("3rdparty/compiler-rt")
 
 # initial variables

include/tvm/relay/error.h

@@ -7,25 +7,134 @@
 #define TVM_RELAY_ERROR_H_
 
 #include <string>
+#include <vector>
+#include <sstream>
 #include "./base.h"
+#include "./expr.h"
+#include "./module.h"
 
 namespace tvm {
 namespace relay {
 
-struct Error : public dmlc::Error {
-  explicit Error(const std::string &msg) : dmlc::Error(msg) {}
-};
+#define RELAY_ERROR(msg) (RelayErrorStream() << msg)
+
+// Forward declaratio for RelayErrorStream.
+struct Error;
+
+/*! \brief A wrapper around std::stringstream.
+ *
+ * This is designed to avoid platform specific
+ * issues compiling and using std::stringstream
+ * for error reporting.
+ */
+struct RelayErrorStream {
+  std::stringstream ss;
+
+  template<typename T>
+  RelayErrorStream& operator<<(const T& t) {
+    ss << t;
+    return *this;
+  }
 
-struct InternalError : public Error {
-  explicit InternalError(const std::string &msg) : Error(msg) {}
+  std::string str() const {
+    return ss.str();
+  }
+
+  void Raise() const;
 };
 
-struct FatalTypeError : public Error {
-  explicit FatalTypeError(const std::string &s) : Error(s) {}
+struct Error : public dmlc::Error {
+  Span sp;
+  explicit Error(const std::string& msg) : dmlc::Error(msg), sp() {}
+  Error(const std::stringstream& msg) : dmlc::Error(msg.str()), sp() {} // NOLINT(*)
+  Error(const RelayErrorStream& msg) : dmlc::Error(msg.str()), sp() {} // NOLINT(*)
 };
 
-struct TypecheckerError : public Error {
-  explicit TypecheckerError(const std::string &msg) : Error(msg) {}
+/*! \brief An abstraction around how errors are stored and reported.
+ * Designed to be opaque to users, so we can support a robust and simpler
+ * error reporting mode, as well as a more complex mode.
+ *
+ * The first mode is the most accurate: we report a Relay error at a specific
+ * Span, and then render the error message directly against a textual representation
+ * of the program, highlighting the exact lines in which it occurs. This mode is not
+ * implemented in this PR and will not work.
+ *
+ * The second mode is a general-purpose mode, which attempts to annotate the program's
+ * textual format with errors.
+ *
+ * The final mode represents the old mode, if we report an error that has no span or
+ * expression, we will default to throwing an exception with a textual representation
+ * of the error and no indication of where it occured in the original program.
+ *
+ * The latter mode is not ideal, and the goal of the new error reporting machinery is
+ * to avoid ever reporting errors in this style.
+ */
+class ErrorReporter {
+ public:
+  ErrorReporter() : errors_(), node_to_error_() {}
+
+  /*! \brief Report a tvm::relay::Error.
+   *
+   * This API is useful for reporting spanned errors.
+   *
+   * \param err The error to report.
+   */
+  void Report(const Error& err) {
+    if (!err.sp.defined()) {
+      throw err;
+    }
+
+    this->errors_.push_back(err);
+  }
+
+  /*! \brief Report an error against a program, using the full program
+   * error reporting strategy.
+   *
+   * This error reporting method requires the global function in which
+   * to report an error, the expression to report the error on,
+   * and the error object.
+   *
+   * \param global The global function in which the expression is contained.
+   * \param node The expression or type to report the error at.
+   * \param err The error message to report.
+   */
+  inline void ReportAt(const GlobalVar& global, const NodeRef& node, std::stringstream& err) {
+    this->ReportAt(global, node, Error(err));
+  }
+
+  /*! \brief Report an error against a program, using the full program
+   * error reporting strategy.
+   *
+   * This error reporting method requires the global function in which
+   * to report an error, the expression to report the error on,
+   * and the error object.
+   *
+   * \param global The global function in which the expression is contained.
+   * \param node The expression or type to report the error at.
+   * \param err The error to report.
+   */
+  void ReportAt(const GlobalVar& global, const NodeRef& node, const Error& err);
+
+  /*! \brief Render all reported errors and exit the program.
+   *
+   * This function should be used after executing a pass to render reported errors.
+   *
+   * It will build an error message from the set of errors, depending on the error
+   * reporting strategy.
+   *
+   * \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);
+
+  inline bool AnyErrors() {
+    return errors_.size() != 0;
+  }
+
+ private:
+  std::vector<Error> errors_;
+  std::unordered_map<NodeRef, std::vector<size_t>, NodeHash, NodeEqual> node_to_error_;
+  std::unordered_map<NodeRef, GlobalVar, NodeHash, NodeEqual> node_to_gv_;
 };
 
 }  // namespace relay

include/tvm/relay/module.h

@@ -43,11 +43,15 @@ class ModuleNode : public RelayNode {
   /*! \brief A map from ids to all global functions. */
   tvm::Map<GlobalVar, Function> functions;
 
+  /*! \brief The entry function (i.e. "main"). */
+  GlobalVar entry_func;
+
   ModuleNode() {}
 
   void VisitAttrs(tvm::AttrVisitor* v) final {
     v->Visit("functions", &functions);
     v->Visit("global_var_map_", &global_var_map_);
+    v->Visit("entry_func", &entry_func);
   }
 
   TVM_DLL static Module make(tvm::Map<GlobalVar, Function> global_funcs);
@@ -111,6 +115,20 @@ class ModuleNode : public RelayNode {
    */
   void Update(const Module& other);
 
+  /*! \brief Construct a module from a standalone expression.
+   *
+   * Allows one to optionally pass a global function map as
+   * well.
+   *
+   * \param expr The expression to set as the entry point to the module.
+   * \param global_funcs The global function map.
+   *
+   * \returns A module with expr set as the entry point.
+   */
+  static Module FromExpr(
+    const Expr& expr,
+    const tvm::Map<GlobalVar, Function>& global_funcs = {});
+
   static constexpr const char* _type_key = "relay.Module";
   TVM_DECLARE_NODE_TYPE_INFO(ModuleNode, Node);
 
@@ -132,6 +150,7 @@ struct Module : public NodeRef {
   using ContainerType = ModuleNode;
 };
 
+
 }  // namespace relay
 }  // namespace tvm
 

include/tvm/relay/pass.h

@@ -6,8 +6,8 @@
 #ifndef TVM_RELAY_PASS_H_
 #define TVM_RELAY_PASS_H_
 
-#include <tvm/relay/module.h>
 #include <tvm/relay/expr.h>
+#include <tvm/relay/module.h>
 #include <tvm/relay/op_attr_types.h>
 #include <string>
 

include/tvm/relay/type.h

@@ -295,6 +295,12 @@ class TypeReporterNode : public Node {
    */
   TVM_DLL virtual bool AssertEQ(const IndexExpr& lhs, const IndexExpr& rhs) = 0;
 
+  /*!
+   * \brief Set the location at which to report unification errors.
+   * \param ref The program node to report the error.
+   */
+  TVM_DLL virtual void SetLocation(const NodeRef& ref) = 0;
+
   // solver is not serializable.
   void VisitAttrs(tvm::AttrVisitor* v) final {}
 

src/relay/ir/error.cc

@@ -0,0 +1,128 @@
+/*!
+ *  Copyright (c) 2018 by Contributors
+ * \file error_reporter.h
+ * \brief The set of errors raised by Relay.
+ */
+
+#include <tvm/relay/expr.h>
+#include <tvm/relay/module.h>
+#include <tvm/relay/error.h>
+#include <string>
+#include <vector>
+#include <rang.hpp>
+
+namespace tvm {
+namespace relay {
+
+void RelayErrorStream::Raise() const {
+  throw Error(*this);
+}
+
+template<typename T, typename U>
+using NodeMap = std::unordered_map<T, U, NodeHash, NodeEqual>;
+
+void ErrorReporter::RenderErrors(const Module& module, bool use_color) {
+  // First we pick an error reporting strategy for each error.
+  // TODO(@jroesch): Spanned errors are currently not supported.
+  for (auto err : this->errors_) {
+    CHECK(!err.sp.defined()) << "attempting to use spanned errors, currently not supported";
+  }
+
+  NodeMap<GlobalVar, NodeMap<NodeRef, std::string>> error_maps;
+
+  // Set control mode in order to produce colors;
+  if (use_color) {
+    rang::setControlMode(rang::control::Force);
+  }
+
+  for (auto pair : this->node_to_gv_) {
+    auto node = pair.first;
+    auto global = Downcast<GlobalVar>(pair.second);
+
+    auto has_errs = this->node_to_error_.find(node);
+
+    CHECK(has_errs != this->node_to_error_.end());
+
+    const auto& error_indicies = has_errs->second;
+
+    std::stringstream err_msg;
+
+    err_msg << rang::fg::red;
+    for (auto index : error_indicies) {
+      err_msg << this->errors_[index].what() << "; ";
+    }
+    err_msg << rang::fg::reset;
+
+    // Setup error map.
+    auto it = error_maps.find(global);
+    if (it != error_maps.end()) {
+      it->second.insert({ node, err_msg.str() });
+    } else {
+      error_maps.insert({ global, { { node, err_msg.str() }}});
+    }
+  }
+
+  // Now we will construct the fully-annotated program to display to
+  // the user.
+  std::stringstream annotated_prog;
+
+  // First we output a header for the errors.
+  annotated_prog <<
+  rang::style::bold << std::endl <<
+  "Error(s) have occurred. We have annotated the program with them:"
+  << std::endl << std::endl << rang::style::reset;
+
+  // For each global function which contains errors, we will
+  // construct an annotated function.
+  for (auto pair : error_maps) {
+    auto global = pair.first;
+    auto err_map = pair.second;
+    auto func = module->Lookup(global);
+
+    // We output the name of the function before displaying
+    // the annotated program.
+    annotated_prog <<
+      rang::style::bold <<
+      "In `" << global->name_hint << "`: " <<
+      std::endl <<
+      rang::style::reset;
+
+    // We then call into the Relay printer to generate the program.
+    //
+    // The annotation callback will annotate the error messages
+    // contained in the map.
+    annotated_prog << RelayPrint(func, false, [&err_map](tvm::relay::Expr expr) {
+      auto it = err_map.find(expr);
+      if (it != err_map.end()) {
+        return it->second;
+      } else {
+        return std::string("");
+      }
+    });
+  }
+
+  auto msg = annotated_prog.str();
+
+  if (use_color) {
+    rang::setControlMode(rang::control::Auto);
+  }
+
+  // Finally we report the error, currently we do so to LOG(FATAL),
+  // it may be good to instead report it to std::cout.
+  LOG(FATAL) << annotated_prog.str() << std::endl;
+}
+
+void ErrorReporter::ReportAt(const GlobalVar& global, const NodeRef& node, const Error& err) {
+  size_t index_to_insert = this->errors_.size();
+  this->errors_.push_back(err);
+  auto it = this->node_to_error_.find(node);
+  if (it != this->node_to_error_.end()) {
+    it->second.push_back(index_to_insert);
+  } else {
+    this->node_to_error_.insert({ node, { index_to_insert }});
+  }
+  this->node_to_gv_.insert({ node, global });
+}
+
+}  // namespace relay
+}  // namespace tvm

src/relay/ir/module.cc

@@ -23,6 +23,8 @@ Module ModuleNode::make(tvm::Map<GlobalVar, Function> global_funcs) {
         << "Duplicate global function name " << kv.first->name_hint;
     n->global_var_map_.Set(kv.first->name_hint, kv.first);
   }
+
+  n->entry_func = GlobalVarNode::make("main");
   return Module(n);
 }
 
@@ -96,6 +98,21 @@ void ModuleNode::Update(const Module& mod) {
   }
 }
 
+Module ModuleNode::FromExpr(
+  const Expr& expr,
+  const tvm::Map<GlobalVar, Function>& global_funcs) {
+  auto mod = ModuleNode::make(global_funcs);
+  auto func_node = expr.as<FunctionNode>();
+  Function func;
+  if (func_node) {
+    func = GetRef<Function>(func_node);
+  } else {
+    func = FunctionNode::make({}, expr, Type(), {}, {});
+  }
+  mod->Add(mod->entry_func, func);
+  return mod;
+}
+
 TVM_REGISTER_NODE_TYPE(ModuleNode);
 
 TVM_REGISTER_API("relay._make.Module")