Harden writer of munged bitcode for fuzzing

include/llvm/Bitcode/NaCl/NaClBitstreamWriter.h

 //===- NaClBitstreamWriter.h - NaCl bitstream writer ------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This header defines the BitstreamWriter class.  This class can be used to
@@ skipping 130 matching lines @@
     }
   }
 
   void initFromHeader(const NaClBitcodeHeader &Header) {
     AlignBitcodeRecords = Header.getAlignBitcodeRecords();
   }
 
   /// \brief Retrieve the current position in the stream, in bits.
   uint64_t GetCurrentBitNo() const { return GetBufferOffset() * 8 + CurBit; }
 
+  /// \brief Returns the maximum abbreviation index allowed for the
+  /// current block.
+  size_t getMaxCurAbbrevIndex() const {
+    return CurAbbrevs.size() + naclbitc::DEFAULT_MAX_ABBREV;
+  }
+
   //===--------------------------------------------------------------------===//
   // Basic Primitives for emitting bits to the stream.
   //===--------------------------------------------------------------------===//
 
   void Emit(uint32_t Val, unsigned NumBits) {
     assert(NumBits && NumBits <= 32 && "Invalid value size!");
     assert((Val & ~(~0U >> (32-NumBits))) == 0 && "High bits set!");
     CurValue |= Val << CurBit;
     if (CurBit + NumBits < 32) {
       CurBit += NumBits;
@@ skipping 364 matching lines @@
     Info.Abbrevs.push_back(Abbv);
 
     return Info.Abbrevs.size()-1+naclbitc::FIRST_APPLICATION_ABBREV;
   }
 };
 
 
 } // End llvm namespace
 
 #endif