Tweak the data layout for the on-disk hash table of identifiers in the PCH file so that the key layout matches that of the PTH key layout

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@70066 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 8 insertions, 2 deletions

diff --git a/lib/Frontend/PCHReader.cpp b/lib/Frontend/PCHReader.cpp
index 005436dccf..2d894774a1 100644
--- a/lib/Frontend/PCHReader.cpp
+++ b/lib/Frontend/PCHReader.cpp
@@ -1245,8 +1245,8 @@ public:
   static std::pair<unsigned, unsigned>
   ReadKeyDataLength(const unsigned char*& d) {
     using namespace clang::io;
-    unsigned KeyLen = ReadUnalignedLE16(d);
     unsigned DataLen = ReadUnalignedLE16(d);
+    unsigned KeyLen = ReadUnalignedLE16(d);
     return std::make_pair(KeyLen, DataLen);
   }
     
diff --git a/lib/Frontend/PCHWriter.cpp b/lib/Frontend/PCHWriter.cpp
index 4ac836419e..7eb398c166 100644
--- a/lib/Frontend/PCHWriter.cpp
+++ b/lib/Frontend/PCHWriter.cpp
@@ -2013,7 +2013,6 @@ public:
     EmitKeyDataLength(llvm::raw_ostream& Out, const IdentifierInfo* II, 
                       pch::IdentID ID) {
     unsigned KeyLen = strlen(II->getName()) + 1;
-    clang::io::Emit16(Out, KeyLen);
     unsigned DataLen = 4 + 4; // 4 bytes for token ID, builtin, flags
                               // 4 bytes for the persistent ID
     if (II->hasMacroDefinition() && 
@@ -2023,7 +2022,14 @@ public:
                                    DEnd = IdentifierResolver::end();
          D != DEnd; ++D)
       DataLen += sizeof(pch::DeclID);
+
+    // We emit the data length before the key length, because we want
+    // the key length to immediately precede the actual string
+    // data. This is so that our identifier length + key layout
+    // matches that of the identifier hash table for pretokenized
+    // headers.
     clang::io::Emit16(Out, DataLen);
+    clang::io::Emit16(Out, KeyLen);
     return std::make_pair(KeyLen, DataLen);
   }