Add (unsupported experimental) feature allowing byte aligned bitcode.

lib/Bitcode/NaCl/Analysis/NaClCompress.cpp

Index: lib/Bitcode/NaCl/Analysis/NaClCompress.cpp
diff --git a/lib/Bitcode/NaCl/Analysis/NaClCompress.cpp b/lib/Bitcode/NaCl/Analysis/NaClCompress.cpp
index d4c327f6b189c8951c6ca8234b12165ca9b6a0f4..c69c815f562c7a93d9855db9ce20596882efc377 100644
--- a/lib/Bitcode/NaCl/Analysis/NaClCompress.cpp
+++ b/lib/Bitcode/NaCl/Analysis/NaClCompress.cpp
@@ -1158,14 +1158,21 @@ static bool analyzeBitcode(
 
   const unsigned char *BufPtr = (const unsigned char *)MemBuf->getBufferStart();
   const unsigned char *EndBufPtr = BufPtr+MemBuf->getBufferSize();
+  const unsigned char *HeaderPtr = BufPtr;
 
   // First read header and verify it is good.
   NaClBitcodeHeader Header;
-  if (Header.Read(BufPtr, EndBufPtr) || !Header.IsSupported())
+  if (Header.Read(HeaderPtr, EndBufPtr))
     return Error("Invalid PNaCl bitcode header");
+  if (!Header.IsSupported()) {
+    errs() << Header.Unsupported();
+    if (!Header.IsReadable())
+      return Error("Invalid PNaCl bitcode header");
+  }
 
   // Create a bitstream reader to read the bitcode file.
-  NaClBitstreamReader StreamFile(BufPtr, EndBufPtr);
+  NaClBitstreamReader StreamFile(
+      getNonStreamedMemoryObject(BufPtr, EndBufPtr), Header);
   NaClBitstreamCursor Stream(StreamFile);
 
   // Parse the the bitcode file.
@@ -1381,15 +1388,17 @@ static bool chooseAbbrevs(MemoryBuffer *MemBuf, BlockAbbrevsMapType &AbbrevsMap,
                           BlockAbbrevsQueueMap &AbbrevsQueueMap) {
   const unsigned char *BufPtr = (const unsigned char *)MemBuf->getBufferStart();
   const unsigned char *EndBufPtr = BufPtr + MemBuf->getBufferSize();
+  const unsigned char *HeaderPtr = BufPtr;
 
   // Read header. No verification is needed since AnalyzeBitcode has
   // already checked it.
   NaClBitcodeHeader Header;
-  if (Header.Read(BufPtr, EndBufPtr))
+  if (Header.Read(HeaderPtr, EndBufPtr))
     return Error("Invalid PNaCl bitcode header");
 
   // Create the bitcode reader.
-  NaClBitstreamReader StreamFile(BufPtr, EndBufPtr);
+  NaClBitstreamReader StreamFile(
+      getNonStreamedMemoryObject(BufPtr, EndBufPtr), Header);
   NaClBitstreamCursor Stream(StreamFile);
 
   // Set up the parser.
@@ -1579,15 +1588,17 @@ static bool copyBitcode(const NaClBitcodeCompressor::CompressFlags &Flags,
 
   const unsigned char *BufPtr = (const unsigned char *)MemBuf->getBufferStart();
   const unsigned char *EndBufPtr = BufPtr + MemBuf->getBufferSize();
+  const unsigned char *HeaderPtr = BufPtr;
 
   // Read header. No verification is needed since AnalyzeBitcode has
   // already checked it.
   NaClBitcodeHeader Header;
-  if (Header.Read(BufPtr, EndBufPtr))
+  if (Header.Read(HeaderPtr, EndBufPtr))
     return Error("Invalid PNaCl bitcode header");
 
   // Create the bitcode reader.
-  NaClBitstreamReader StreamFile(BufPtr, EndBufPtr);
+  NaClBitstreamReader StreamFile(
+      getNonStreamedMemoryObject(BufPtr, EndBufPtr), Header);
   NaClBitstreamCursor Stream(StreamFile);
 
   // Create the bitcode writer.