[PCH] For HeaderFileInfoTrait, hash the key using size & time of the file.

Previously the hash would be the filename portion of the path, which could be
different for a filename with different case or a symbolic link with a different
name completely.
This did not actually create any issue so far because by validating all headers
in the PCH we created uniqued FileEntries based on inodes, so an #include of
a symbolic link (refering to a file from the PCH) would end up with a FileEntry
with filename same as the one recorded in the PCH.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176566 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 28 insertions, 14 deletions

diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 53474f5b0b..d62c42bb1b 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -41,6 +41,7 @@
 #include "clang/Serialization/GlobalModuleIndex.h"
 #include "clang/Serialization/ModuleManager.h"
 #include "clang/Serialization/SerializationDiagnostic.h"
+#include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Bitcode/BitstreamReader.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -1294,24 +1295,28 @@ ASTReader::getGlobalPreprocessedEntityID(ModuleFile &M, unsigned LocalID) const
   return LocalID + I->second;
 }
 
-unsigned HeaderFileInfoTrait::ComputeHash(const char *path) {
-  return llvm::HashString(llvm::sys::path::filename(path));
+unsigned HeaderFileInfoTrait::ComputeHash(internal_key_ref ikey) {
+  return llvm::hash_combine(ikey.Size, ikey.ModTime);
 }
     
 HeaderFileInfoTrait::internal_key_type 
-HeaderFileInfoTrait::GetInternalKey(const char *path) { return path; }
+HeaderFileInfoTrait::GetInternalKey(const FileEntry *FE) {
+  internal_key_type ikey = { FE->getSize(), FE->getModificationTime(),
+                             FE->getName() };
+  return ikey;
+}
     
-bool HeaderFileInfoTrait::EqualKey(internal_key_type a, internal_key_type b) {
-  if (strcmp(a, b) == 0)
-    return true;
-  
-  if (llvm::sys::path::filename(a) != llvm::sys::path::filename(b))
+bool HeaderFileInfoTrait::EqualKey(internal_key_ref a, internal_key_ref b) {
+  if (a.Size != b.Size || a.ModTime != b.ModTime)
     return false;
 
+  if (strcmp(a.Filename, b.Filename) == 0)
+    return true;
+  
   // Determine whether the actual files are equivalent.
   FileManager &FileMgr = Reader.getFileManager();
-  const FileEntry *FEA = FileMgr.getFile(a);
-  const FileEntry *FEB = FileMgr.getFile(b);
+  const FileEntry *FEA = FileMgr.getFile(a.Filename);
+  const FileEntry *FEB = FileMgr.getFile(b.Filename);
   return (FEA && FEA == FEB);
 }
     
@@ -1319,11 +1324,20 @@ std::pair<unsigned, unsigned>
 HeaderFileInfoTrait::ReadKeyDataLength(const unsigned char*& d) {
   unsigned KeyLen = (unsigned) clang::io::ReadUnalignedLE16(d);
   unsigned DataLen = (unsigned) *d++;
-  return std::make_pair(KeyLen + 1, DataLen);
+  return std::make_pair(KeyLen, DataLen);
 }
-    
+
+HeaderFileInfoTrait::internal_key_type
+HeaderFileInfoTrait::ReadKey(const unsigned char *d, unsigned) {
+  internal_key_type ikey;
+  ikey.Size = off_t(clang::io::ReadUnalignedLE64(d));
+  ikey.ModTime = time_t(clang::io::ReadUnalignedLE64(d));
+  ikey.Filename = (const char *)d;
+  return ikey;
+}
+
 HeaderFileInfoTrait::data_type 
-HeaderFileInfoTrait::ReadData(const internal_key_type, const unsigned char *d,
+HeaderFileInfoTrait::ReadData(internal_key_ref, const unsigned char *d,
                               unsigned DataLen) {
   const unsigned char *End = d + DataLen;
   using namespace clang::io;
@@ -4109,7 +4123,7 @@ namespace {
         return false;
 
       // Look in the on-disk hash table for an entry for this file name.
-      HeaderFileInfoLookupTable::iterator Pos = Table->find(This->FE->getName());
+      HeaderFileInfoLookupTable::iterator Pos = Table->find(This->FE);
       if (Pos == Table->end())
         return false;