+ /// isBitcodeWrapper - Return true if the given bytes are the magic bytes
+ /// for an LLVM IR bitcode wrapper.
+ ///
+ static inline bool isBitcodeWrapper(const unsigned char *BufPtr,
+ const unsigned char *BufEnd) {
+ // See if you can find the hidden message in the magic bytes :-).
+ // (Hint: it's a little-endian encoding.)
+ return BufPtr != BufEnd &&
+ BufPtr[0] == 0xDE &&
+ BufPtr[1] == 0xC0 &&
+ BufPtr[2] == 0x17 &&
+ BufPtr[3] == 0x0B;
+ }
+
+ /// isRawBitcode - Return true if the given bytes are the magic bytes for
+ /// raw LLVM IR bitcode (without a wrapper).
+ ///
+ static inline bool isRawBitcode(const unsigned char *BufPtr,
+ const unsigned char *BufEnd) {
+ // These bytes sort of have a hidden message, but it's not in
+ // little-endian this time, and it's a little redundant.
+ return BufPtr != BufEnd &&
+ BufPtr[0] == 'B' &&
+ BufPtr[1] == 'C' &&
+ BufPtr[2] == 0xc0 &&
+ BufPtr[3] == 0xde;
+ }
+
+ /// isBitcode - Return true if the given bytes are the magic bytes for
+ /// LLVM IR bitcode, either with or without a wrapper.
+ ///
+ static bool inline isBitcode(const unsigned char *BufPtr,
+ const unsigned char *BufEnd) {
+ return isBitcodeWrapper(BufPtr, BufEnd) ||
+ isRawBitcode(BufPtr, BufEnd);
+ }
+
+ /// SkipBitcodeWrapperHeader - Some systems wrap bc files with a special
+ /// header for padding or other reasons. The format of this header is:
+ ///
+ /// struct bc_header {
+ /// uint32_t Magic; // 0x0B17C0DE
+ /// uint32_t Version; // Version, currently always 0.
+ /// uint32_t BitcodeOffset; // Offset to traditional bitcode file.
+ /// uint32_t BitcodeSize; // Size of traditional bitcode file.
+ /// ... potentially other gunk ...
+ /// };
+ ///
+ /// This function is called when we find a file with a matching magic number.
+ /// In this case, skip down to the subsection of the file that is actually a
+ /// BC file.
+ static inline bool SkipBitcodeWrapperHeader(unsigned char *&BufPtr,
+ unsigned char *&BufEnd) {
+ enum {
+ KnownHeaderSize = 4*4, // Size of header we read.
+ OffsetField = 2*4, // Offset in bytes to Offset field.
+ SizeField = 3*4 // Offset in bytes to Size field.
+ };
+
+ // Must contain the header!
+ if (BufEnd-BufPtr < KnownHeaderSize) return true;
+
+ unsigned Offset = ( BufPtr[OffsetField ] |
+ (BufPtr[OffsetField+1] << 8) |
+ (BufPtr[OffsetField+2] << 16) |
+ (BufPtr[OffsetField+3] << 24));
+ unsigned Size = ( BufPtr[SizeField ] |
+ (BufPtr[SizeField +1] << 8) |
+ (BufPtr[SizeField +2] << 16) |
+ (BufPtr[SizeField +3] << 24));
+
+ // Verify that Offset+Size fits in the file.
+ if (Offset+Size > unsigned(BufEnd-BufPtr))
+ return true;
+ BufPtr += Offset;
+ BufEnd = BufPtr+Size;
+ return false;
+ }