4 files changed, 82 insertions, 1 deletions

diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
index 9f015eaa230..aeca83a9071 100644
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -283,6 +283,44 @@ class Preprocessor {
   /// This is used when loading a precompiled preamble.
   std::pair<int, bool> SkipMainFilePreamble;
 
+  class PreambleConditionalStackStore {
+    enum State {
+      Off = 0,
+      Recording = 1,
+      Replaying = 2,
+    };
+
+  public:
+    PreambleConditionalStackStore() : ConditionalStackState(Off) {}
+
+    void startRecording() { ConditionalStackState = Recording; }
+    void startReplaying() { ConditionalStackState = Replaying; }
+    bool isRecording() const { return ConditionalStackState == Recording; }
+    bool isReplaying() const { return ConditionalStackState == Replaying; }
+
+    ArrayRef<PPConditionalInfo> getStack() const {
+      return ConditionalStack;
+    }
+
+    void doneReplaying() {
+      ConditionalStack.clear();
+      ConditionalStackState = Off;
+    }
+
+    void setStack(ArrayRef<PPConditionalInfo> s) {
+      if (!isRecording() && !isReplaying())
+        return;
+      ConditionalStack.clear();
+      ConditionalStack.append(s.begin(), s.end());
+    }
+
+    bool hasRecordedPreamble() const { return !ConditionalStack.empty(); }
+
+  private:
+    SmallVector<PPConditionalInfo, 4> ConditionalStack;
+    State ConditionalStackState;
+  } PreambleConditionalStack;
+
   /// \brief The current top of the stack that we're lexing from if
   /// not expanding a macro and we are lexing directly from source code.
   ///
@@ -1695,6 +1733,11 @@ public:
   /// \brief Return true if we're in the top-level file, not in a \#include.
   bool isInPrimaryFile() const;
 
+  /// \brief Return true if we're in the main file (specifically, if we are 0
+  /// (zero) levels deep \#include. This is used by the lexer to determine if
+  /// it needs to generate errors about unterminated \#if directives.
+  bool isInMainFile() const;
+
   /// \brief Handle cases where the \#include name is expanded
   /// from a macro as multiple tokens, which need to be glued together. 
   ///
@@ -1932,6 +1975,27 @@ public:
                                                           Module *M,
                                                           SourceLocation MLoc);
 
+  bool isRecordingPreamble() const {
+    return PreambleConditionalStack.isRecording();
+  }
+
+  bool hasRecordedPreamble() const {
+    return PreambleConditionalStack.hasRecordedPreamble();
+  }
+
+  ArrayRef<PPConditionalInfo> getPreambleConditionalStack() const {
+      return PreambleConditionalStack.getStack();
+  }
+
+  void setRecordedPreambleConditionalStack(ArrayRef<PPConditionalInfo> s) {
+    PreambleConditionalStack.setStack(s);
+  }
+
+  void setReplayablePreambleConditionalStack(ArrayRef<PPConditionalInfo> s) {
+    PreambleConditionalStack.startReplaying();
+    PreambleConditionalStack.setStack(s);
+  }
+
 private:
   // Macro handling.
   void HandleDefineDirective(Token &Tok, bool ImmediatelyAfterTopLevelIfndef);
diff --git a/clang/include/clang/Lex/PreprocessorLexer.h b/clang/include/clang/Lex/PreprocessorLexer.h
index 6d6cf05a96c..5c2e4d41454 100644
--- a/clang/include/clang/Lex/PreprocessorLexer.h
+++ b/clang/include/clang/Lex/PreprocessorLexer.h
@@ -17,6 +17,7 @@
 
 #include "clang/Lex/MultipleIncludeOpt.h"
 #include "clang/Lex/Token.h"
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallVector.h"
 
 namespace clang {
@@ -176,6 +177,11 @@ public:
   conditional_iterator conditional_end() const { 
     return ConditionalStack.end(); 
   }
+
+  void setConditionalLevels(ArrayRef<PPConditionalInfo> CL) {
+    ConditionalStack.clear();
+    ConditionalStack.append(CL.begin(), CL.end());
+  }
 };
 
 }  // end namespace clang
diff --git a/clang/include/clang/Lex/PreprocessorOptions.h b/clang/include/clang/Lex/PreprocessorOptions.h
index 58d79f7ff81..c85d2384fa4 100644
--- a/clang/include/clang/Lex/PreprocessorOptions.h
+++ b/clang/include/clang/Lex/PreprocessorOptions.h
@@ -80,7 +80,14 @@ public:
   /// The boolean indicates whether the preamble ends at the start of a new
   /// line.
   std::pair<unsigned, bool> PrecompiledPreambleBytes;
-  
+
+  /// \brief True indicates that a preamble is being generated.
+  ///
+  /// When the lexer is done, one of the things that need to be preserved is the
+  /// conditional #if stack, so the ASTWriter/ASTReader can save/restore it when
+  /// processing the rest of the file.
+  bool GeneratePreamble;
+
   /// The implicit PTH input included at the start of the translation unit, or
   /// empty.
   std::string ImplicitPTHInclude;
@@ -144,6 +151,7 @@ public:
                           AllowPCHWithCompilerErrors(false),
                           DumpDeserializedPCHDecls(false),
                           PrecompiledPreambleBytes(0, true),
+                          GeneratePreamble(false),
                           RemappedFilesKeepOriginalName(true),
                           RetainRemappedFileBuffers(false),
                           ObjCXXARCStandardLibrary(ARCXX_nolib) { }
diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index 823440b1971..6b40781a123 100644
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -607,6 +607,9 @@ namespace clang {
 
       /// \brief Record code for \#pragma pack options.
       PACK_PRAGMA_OPTIONS = 61,
+
+      /// \brief The stack of open #ifs/#ifdefs recorded in a preamble.
+      PP_CONDITIONAL_STACK = 62,
     };
 
     /// \brief Record types used within a source manager block.