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

include/llvm/MC/MCObjectStreamer.h

 //===- MCObjectStreamer.h - MCStreamer Object File Interface ----*- 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_MCOBJECTSTREAMER_H
@@ skipping 26 matching lines @@
   MCSectionData *CurSectionData;
   MCSectionData::iterator CurInsertionPoint;
   bool EmitEHFrame;
   bool EmitDebugFrame;
   SmallVector<MCSymbolData *, 2> PendingLabels;
 
   virtual void EmitInstToData(const MCInst &Inst, const MCSubtargetInfo&) = 0;
   void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override;
   void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override;
 
-  // If any labels have been emitted but not assigned fragments, ensure that
-  // they get assigned, either to F if possible or to a new data fragment.
-  void flushPendingLabels(MCFragment *F);
-
 protected:
   MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB, raw_ostream &_OS,
                    MCCodeEmitter *_Emitter);
   MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB, raw_ostream &_OS,
                    MCCodeEmitter *_Emitter, MCAssembler *_Assembler);
   ~MCObjectStreamer();
 
 public:
   /// state management
   void reset() override;
@@ skipping 17 matching lines @@
   void insert(MCFragment *F) {
     flushPendingLabels(F);
     CurSectionData->getFragmentList().insert(CurInsertionPoint, F);
     F->setParent(CurSectionData);
   }
 
   /// Get a data fragment to write into, creating a new one if the current
   /// fragment is not a data fragment.
   MCDataFragment *getOrCreateDataFragment();
 
+  /// If any labels have been emitted but not assigned fragments, ensure that
+  /// they get assigned, either to F if possible or to a new data fragment.
+  /// Optionally, it is also possible to provide an offset \p FOffset, which
+  /// will be used as a symbol offset within the fragment.
+  void flushPendingLabels(MCFragment *F, uint64_t FOffset = 0);
+
 public:
   void visitUsedSymbol(const MCSymbol &Sym) override;
 
   MCAssembler &getAssembler() { return *Assembler; }
 
   /// @name MCStreamer Interface
   /// @{
 
   void EmitLabel(MCSymbol *Symbol) override;
   void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) override;
@@ skipping 36 matching lines @@
   void FinishImpl() override;
 
   bool mayHaveInstructions() const override {
     return getCurrentSectionData()->hasInstructions();
   }
 };
 
 } // end namespace llvm
 
 #endif