Cherry-pick r234714: [MC] Write padding into fragments when -mc-relax-all flag is used

include/llvm/MC/MCAssembler.h

 //===- MCAssembler.h - Object File Generation -------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_MC_MCASSEMBLER_H
@@ skipping 1225 matching lines @@
   const_file_name_iterator file_names_end() const {
     return FileNames.end();
   }
 
   void addFileName(StringRef FileName) {
     if (std::find(file_names_begin(), file_names_end(), FileName) ==
         file_names_end())
       FileNames.push_back(FileName);
   }
 
+  /// \brief Write the necessary bundle padding to the given object writer.
+  /// Expects a fragment \p F containing instructions and its size \p FSize.
+  void writeFragmentPadding(const MCFragment &F, uint64_t FSize,
+                            MCObjectWriter *OW) const;
+
   /// @}
 
   void dump();
 };
 
+/// \brief Compute the amount of padding required before the fragment \p F to
+/// obey bundling restrictions, where \p FOffset is the fragment's offset in
+/// its section and \p FSize is the fragment's size.
+uint64_t computeBundlePadding(const MCAssembler &Assembler,
+                              const MCFragment *F,
+                              uint64_t FOffset, uint64_t FSize);
+
 } // end namespace llvm
 
 #endif