ASTReader: Treat InputFileOffsets as unaligned to avoid UB

This is a better approach to fixing the undefined behaviour I tried to
fix in r240228. This data doesn't necessarily have suitable alignment
for uint64_t, so use unaligned_uint64_t instead.

This fixes 225 test failures when clang is built with ubsan.

llvm-svn: 240247

2 files changed, 4 insertions, 2 deletions

diff --git a/clang/include/clang/Serialization/Module.h b/clang/include/clang/Serialization/Module.h
index 5571d91a541..c98ced41aae 100644
--- a/clang/include/clang/Serialization/Module.h
+++ b/clang/include/clang/Serialization/Module.h
@@ -20,6 +20,7 @@
 #include "clang/Serialization/ContinuousRangeMap.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/Bitcode/BitstreamReader.h"
+#include "llvm/Support/Endian.h"
 #include <memory>
 #include <string>
 
@@ -206,7 +207,7 @@ public:
   llvm::BitstreamCursor InputFilesCursor;
 
   /// \brief Offsets for all of the input file entries in the AST file.
-  const uint64_t *InputFileOffsets;
+  const llvm::support::unaligned_uint64_t *InputFileOffsets;
 
   /// \brief The input files that have been loaded from this AST file.
   std::vector<InputFile> InputFilesLoaded;
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index d75b5eb73d5..7242793be22 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -2307,7 +2307,8 @@ ASTReader::ReadControlBlock(ModuleFile &F,
     case INPUT_FILE_OFFSETS:
       NumInputs = Record[0];
       NumUserInputs = Record[1];
-      F.InputFileOffsets = (const uint64_t *)Blob.data();
+      F.InputFileOffsets =
+          (const llvm::support::unaligned_uint64_t *)Blob.data();
       F.InputFilesLoaded.resize(NumInputs);
       break;
     }