If the bitcode reader input stream isn't a multiple of 4 bytes, it's more

likely not a bitcode file at all, rather than being a bitcode file which
is truncated. Check for this case and issue a more relevant error message.

llvm-svn: 100156

1 files changed, 7 insertions, 3 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index b9453c90b58..76d112e045a 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1527,12 +1527,16 @@ bool BitcodeReader::ParseModule() {
 bool BitcodeReader::ParseBitcodeInto(Module *M) {
   TheModule = 0;
 
-  if (Buffer->getBufferSize() & 3)
-    return Error("Bitcode stream should be a multiple of 4 bytes in length");
-
   unsigned char *BufPtr = (unsigned char *)Buffer->getBufferStart();
   unsigned char *BufEnd = BufPtr+Buffer->getBufferSize();
 
+  if (Buffer->getBufferSize() & 3) {
+    if (!isRawBitcode(BufPtr, BufEnd) && !isBitcodeWrapper(BufPtr, BufEnd))
+      return Error("Invalid bitcode signature");
+    else
+      return Error("Bitcode stream should be a multiple of 4 bytes in length");
+  }
+
   // If we have a wrapper header, parse it and ignore the non-bc file contents.
   // The magic number is 0x0B17C0DE stored in little endian.
   if (isBitcodeWrapper(BufPtr, BufEnd))