From 03569eaabceb14a20e23d043135fdccbc7309a96 Mon Sep 17 00:00:00 2001
From: Argyrios Kyrtzidis <akyrtzi@gmail.com>
Date: Mon, 12 Jul 2010 18:49:30 +0000
Subject: [PATCH] If we are past tok::eof and in caching lex mode, avoid
 caching repeated tok::eofs.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@108175 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/clang/Lex/Preprocessor.h |  6 +++++-
 lib/Lex/PPCaching.cpp            | 16 ++++++++++++----
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/include/clang/Lex/Preprocessor.h b/include/clang/Lex/Preprocessor.h
index f90cb0a687..6c9b9fb96e 100644
--- a/include/clang/Lex/Preprocessor.h
+++ b/include/clang/Lex/Preprocessor.h
@@ -871,7 +871,11 @@ private:
   //===--------------------------------------------------------------------===//
   // Caching stuff.
   void CachingLex(Token &Result);
-  bool InCachingLexMode() const { return CurPPLexer == 0 && CurTokenLexer == 0;}
+  bool InCachingLexMode() const {
+    // If the Lexer pointers are 0 and IncludeMacroStack is empty, it means
+    // that we are past EOF, not that we are in CachingLex mode.
+    return CurPPLexer == 0 && CurTokenLexer == 0 && !IncludeMacroStack.empty();
+  }
   void EnterCachingLexMode();
   void ExitCachingLexMode() {
     if (InCachingLexMode())
diff --git a/lib/Lex/PPCaching.cpp b/lib/Lex/PPCaching.cpp
index 20e3b3dd9d..16fcaa365c 100644
--- a/lib/Lex/PPCaching.cpp
+++ b/lib/Lex/PPCaching.cpp
@@ -45,13 +45,19 @@ void Preprocessor::Backtrack() {
 }
 
 void Preprocessor::CachingLex(Token &Result) {
+  if (!InCachingLexMode())
+    return;
+
   if (CachedLexPos < CachedTokens.size()) {
     Result = CachedTokens[CachedLexPos++];
     return;
   }
 
   ExitCachingLexMode();
-  Lex(Result);
+  // True if we consumed everything already.
+  bool PastEOF =  CurPPLexer == 0 && CurTokenLexer == 0;
+  if (!PastEOF)
+    Lex(Result);
 
   if (!isBacktrackEnabled()) {
     // All cached tokens were consumed.
@@ -60,10 +66,12 @@ void Preprocessor::CachingLex(Token &Result) {
     return;
   }
 
-  // Cache the lexed token.
+  // Cache the lexed token if it's not a repeated tok::eof.
   EnterCachingLexMode();
-  CachedTokens.push_back(Result);
-  ++CachedLexPos;
+  if (!PastEOF) {
+    CachedTokens.push_back(Result);
+    ++CachedLexPos;
+  }
 }
 
 void Preprocessor::EnterCachingLexMode() {
-- 
2.40.0