Move nextFile() from LinkingContext to InputGraph.

LinkingContext and InputGraph are unnecessarily entangled. Most linker
input file data, e.g. the vector containing input files, the next index
of the input file, etc. are managed by InputGraph, but only the current
input file is for no obvious reason managed by LinkingContext.

This patch is to move code from LinkingContext to InputGraph to fix it.
It's now clear who's reponsible for managing input file state, which is
InputGraph, and LinkingContext is now free from that responsibility.
It improves the readability as we now have fewer dependencies between
classes. No functionality change.

Differential Revision: http://llvm-reviews.chandlerc.com/D3259

llvm-svn: 205394

lld/include/lld/Core/InputGraph.h

@@ -52,7 +52,22 @@ public:
   enum Position : uint8_t { BEGIN, END };
 
   /// \brief Initialize the inputgraph
-  InputGraph() : _ordinal(0), _nextElementIndex(0) {}
+  InputGraph()
+      : _ordinal(0), _nextElementIndex(0), _currentInputElement(nullptr) {}
+
+  /// nextFile returns the next file that needs to be processed by the resolver.
+  /// When there are no more files to be processed, an appropriate
+  /// InputGraphError is returned. Ordinals are assigned to files returned by
+  /// nextFile, which means ordinals would be assigned in the way files are
+  /// resolved.
+  ErrorOr<File &> nextFile();
+
+  /// Set the resolver state for the current Input element. This is used by the
+  /// InputGraph to decide the next file that needs to be processed for various
+  /// types of nodes in the InputGraph. The resolver state is nothing but a
+  /// bitmask of various types of states that the resolver handles when adding
+  /// atoms.
+  void setResolverState(uint32_t resolverState);
 
   /// \brief Adds a node into the InputGraph
   bool addInputElement(std::unique_ptr<InputElement>);
@@ -74,7 +89,7 @@ public:
     return make_range(_inputArgs.begin(), _inputArgs.end());
   }
 
-  // \brief Does the inputGraph contain any elements
+  // \brief Returns the number of input files.
   size_t size() const { return _inputArgs.size(); }
 
   /// \brief Dump the input Graph
@@ -87,7 +102,7 @@ public:
   /// \brief Insert an element into the input graph at position.
   void insertElementAt(std::unique_ptr<InputElement>, Position position);
 
-  /// \brief Helper functions for the resolver
+  /// \brief Helper functions for the resolver. Exposed for unit tests.
   ErrorOr<InputElement *> getNextInputElement();
 
 protected:
@@ -97,6 +112,7 @@ protected:
   int64_t _ordinal;
   // Index of the next element to be processed
   uint32_t _nextElementIndex;
+  InputElement *_currentInputElement;
 };
 
 /// \brief This describes each element in the InputGraph. The Kind

lld/include/lld/Core/LinkingContext.h

@@ -218,10 +218,11 @@ public:
   bool getAllowDuplicates() const { return _allowDuplicates; }
 
   void appendLLVMOption(const char *opt) { _llvmOptions.push_back(opt); }
-  virtual void setInputGraph(std::unique_ptr<InputGraph> inputGraph) {
+
+  void setInputGraph(std::unique_ptr<InputGraph> inputGraph) {
     _inputGraph = std::move(inputGraph);
   }
-  virtual InputGraph &inputGraph() const { return *_inputGraph; }
+  InputGraph &inputGraph() const { return *_inputGraph; }
 
   /// This method adds undefined symbols specified by the -u option to the to
   /// the list of undefined symbols known to the linker. This option essentially
@@ -300,21 +301,6 @@ public:
   /// \param linkedFile This is the merged/linked graph of all input file Atoms.
   virtual error_code writeFile(const File &linkedFile) const;
 
-  /// nextFile returns the next file that needs to be processed by the resolver.
-  /// The LinkingContext's can override the default behavior to change the way
-  /// the resolver operates. This uses the currentInputElement. When there are
-  /// no more files to be processed an appropriate InputGraphError is
-  /// returned. Ordinals are assigned to files returned by nextFile, which means
-  /// ordinals would be assigned in the way files are resolved.
-  virtual ErrorOr<File &> nextFile();
-
-  /// Set the resolver state for the current Input element This is used by the
-  /// InputGraph to decide the next file that needs to be processed for various
-  /// types of nodes in the InputGraph. The resolver state is nothing but a
-  /// bitmask of various types of states that the resolver handles when adding
-  /// atoms.
-  virtual void setResolverState(uint32_t resolverState);
-
   /// Return the next ordinal and Increment it.
   virtual uint64_t getNextOrdinalAndIncrement() const { return _nextOrdinal++; }
 
@@ -353,7 +339,6 @@ protected:
   StringRefVector _initialUndefinedSymbols;
   std::unique_ptr<InputGraph> _inputGraph;
   mutable llvm::BumpPtrAllocator _allocator;
-  InputElement *_currentInputElement;
   mutable uint64_t _nextOrdinal;
   Registry _registry;
 

lld/lib/Core/InputGraph.cpp

@@ -20,6 +20,37 @@ static bool sortInputElements(const std::unique_ptr<InputElement> &a,
   return a->getOrdinal() < b->getOrdinal();
 }
 
+ErrorOr<File &> InputGraph::nextFile() {
+  // When nextFile() is called for the first time, _currentInputElement is not
+  // initialized. Initialize it with the first element of the input graph.
+  if (_currentInputElement == nullptr) {
+    ErrorOr<InputElement *> elem = getNextInputElement();
+    if (elem.getError() == InputGraphError::no_more_elements)
+      return make_error_code(InputGraphError::no_more_files);
+    _currentInputElement = *elem;
+  }
+
+  // Otherwise, try to get the next file of _currentInputElement. If the current
+  // input element points to an archive file, and there's a file left in the
+  // archive, it will succeed. If not, try to get the next file in the input
+  // graph.
+  for (;;) {
+    ErrorOr<File &> nextFile = _currentInputElement->getNextFile();
+    if (nextFile.getError() != InputGraphError::no_more_files)
+      return std::move(nextFile);
+
+    ErrorOr<InputElement *> elem = getNextInputElement();
+    if (elem.getError() == InputGraphError::no_more_elements ||
+        *elem == nullptr)
+      return make_error_code(InputGraphError::no_more_files);
+    _currentInputElement = *elem;
+  }
+}
+
+void InputGraph::setResolverState(uint32_t state) {
+  _currentInputElement->setResolveState(state);
+}
+
 bool InputGraph::addInputElement(std::unique_ptr<InputElement> ie) {
   _inputArgs.push_back(std::move(ie));
   return true;

lld/lib/Core/LinkingContext.cpp

@@ -25,8 +25,7 @@ LinkingContext::LinkingContext()
       _warnIfCoalesableAtomsHaveDifferentLoadName(false),
       _printRemainingUndefines(true), _allowRemainingUndefines(false),
       _logInputFiles(false), _allowShlibUndefines(false),
-      _outputFileType(OutputFileType::Default), _currentInputElement(nullptr),
-      _nextOrdinal(0) {}
+      _outputFileType(OutputFileType::Default), _nextOrdinal(0) {}
 
 LinkingContext::~LinkingContext() {}
 
@@ -83,37 +82,6 @@ void LinkingContext::createInternalFiles(
     result.push_back(std::move(internalFile));
 }
 
-void LinkingContext::setResolverState(uint32_t state) {
-  _currentInputElement->setResolveState(state);
-}
-
-ErrorOr<File &> LinkingContext::nextFile() {
-  // When nextFile() is called for the first time, _currentInputElement is not
-  // initialized. Initialize it with the first element of the input graph.
-  if (_currentInputElement == nullptr) {
-    ErrorOr<InputElement *> elem = inputGraph().getNextInputElement();
-    if (elem.getError() == InputGraphError::no_more_elements)
-      return make_error_code(InputGraphError::no_more_files);
-    _currentInputElement = *elem;
-  }
-
-  // Otherwise, try to get the next file of _currentInputElement. If the current
-  // input element points to an archive file, and there's a file left in the
-  // archive, it will succeed. If not, try to get the next file in the input
-  // graph.
-  for (;;) {
-    ErrorOr<File &> nextFile = _currentInputElement->getNextFile();
-    if (nextFile.getError() != InputGraphError::no_more_files)
-      return std::move(nextFile);
-
-    ErrorOr<InputElement *> elem = inputGraph().getNextInputElement();
-    if (elem.getError() == InputGraphError::no_more_elements ||
-        *elem == nullptr)
-      return make_error_code(InputGraphError::no_more_files);
-    _currentInputElement = *elem;
-  }
-}
-
 void LinkingContext::addPasses(PassManager &pm) {}
 
 } // end namespace lld

lld/lib/Core/Resolver.cpp

@@ -105,7 +105,7 @@ void Resolver::handleFile(const File &file) {
     doAbsoluteAtom(*absAtom);
     resolverState |= StateNewAbsoluteAtoms;
   }
-  _context.setResolverState(resolverState);
+  _context.inputGraph().setResolverState(resolverState);
 }
 
 void Resolver::forEachUndefines(UndefCallback callback,
@@ -305,8 +305,8 @@ bool Resolver::resolveUndefines() {
   ScopedTask task(getDefaultDomain(), "resolveUndefines");
 
   for (;;) {
-    ErrorOr<File &> file = _context.nextFile();
-    _context.setResolverState(Resolver::StateNoChange);
+    ErrorOr<File &> file = _context.inputGraph().nextFile();
+    _context.inputGraph().setResolverState(Resolver::StateNoChange);
     error_code ec = file.getError();
     if (ec == InputGraphError::no_more_files)
       return true;