When performing typo correction, look through the set of known

identifiers to determine good typo-correction candidates. Once we've
identified those candidates, we perform name lookup on each of them
and the consider the results. 

This optimization makes typo correction > 2x faster on a benchmark
example using a single typo (NSstring) in a tiny file that includes
Cocoa.h from a precompiled header, since we are deserializing far less
information now during typo correction.

There is a semantic change here, which is interesting. The presence of
a similarly-named entity that is not visible can now affect typo
correction. This is both good (you won't get weird corrections if the
thing you wanted isn't in scope) and bad (you won't get good
corrections if there is a similarly-named-but-completely-unrelated
thing). Time will tell whether it was a good choice or not.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@116528 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 62 insertions, 0 deletions

diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 2002ccd1c2..0f7486f82a 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -603,6 +603,10 @@ public:
   static const internal_key_type&
   GetInternalKey(const external_key_type& x) { return x; }
 
+  // This hopefully will just get inlined and removed by the optimizer.
+  static const external_key_type&
+  GetExternalKey(const internal_key_type& x) { return x; }
+
   static std::pair<unsigned, unsigned>
   ReadKeyDataLength(const unsigned char*& d) {
     using namespace clang::io;
@@ -3571,6 +3575,64 @@ IdentifierInfo* ASTReader::get(const char *NameStart, const char *NameEnd) {
   return 0;
 }
 
+namespace clang {
+  /// \brief An identifier-lookup iterator that enumerates all of the
+  /// identifiers stored within a set of AST files.
+  class ASTIdentifierIterator : public IdentifierIterator {
+    /// \brief The AST reader whose identifiers are being enumerated.
+    const ASTReader &Reader;
+
+    /// \brief The current index into the chain of AST files stored in
+    /// the AST reader.
+    unsigned Index;
+
+    /// \brief The current position within the identifier lookup table
+    /// of the current AST file.
+    ASTIdentifierLookupTable::key_iterator Current;
+
+    /// \brief The end position within the identifier lookup table of
+    /// the current AST file.
+    ASTIdentifierLookupTable::key_iterator End;
+
+  public:
+    explicit ASTIdentifierIterator(const ASTReader &Reader);
+
+    virtual llvm::StringRef Next();
+  };
+}
+
+ASTIdentifierIterator::ASTIdentifierIterator(const ASTReader &Reader)
+  : Reader(Reader), Index(Reader.Chain.size() - 1) {
+  ASTIdentifierLookupTable *IdTable
+    = (ASTIdentifierLookupTable *)Reader.Chain[Index]->IdentifierLookupTable;
+  Current = IdTable->key_begin();
+  End = IdTable->key_end();
+}
+
+llvm::StringRef ASTIdentifierIterator::Next() {
+  while (Current == End) {
+    // If we have exhausted all of our AST files, we're done.
+    if (Index == 0)
+      return llvm::StringRef();
+
+    --Index;
+    ASTIdentifierLookupTable *IdTable
+      = (ASTIdentifierLookupTable *)Reader.Chain[Index]->IdentifierLookupTable;
+    Current = IdTable->key_begin();
+    End = IdTable->key_end();
+  }
+
+  // We have any identifiers remaining in the current AST file; return
+  // the next one.
+  std::pair<const char*, unsigned> Key = *Current;
+  ++Current;
+  return llvm::StringRef(Key.first, Key.second);
+}
+
+IdentifierIterator *ASTReader::getIdentifiers() const {
+  return new ASTIdentifierIterator(*this);
+}
+
 std::pair<ObjCMethodList, ObjCMethodList>
 ASTReader::ReadMethodPool(Selector Sel) {
   // Find this selector in a hash table. We want to find the most recent entry.