Provide a shortcut for MCObjectStreamer when emitting fills.

Reduces runtime of i386-large-relocations.s by 10x in Release builds, even more
in Debug+Asserts builds.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164945 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCObjectStreamer.h

@@ -81,6 +81,8 @@ public:
                                          const MCSymbol *Label);
   virtual void EmitGPRel32Value(const MCExpr *Value);
   virtual void EmitGPRel64Value(const MCExpr *Value);
+  virtual void EmitFill(uint64_t NumBytes, uint8_t FillValue,
+                        unsigned AddrSpace);
   virtual void FinishImpl();
 
   /// @}

lib/MC/MCObjectStreamer.cpp

@@ -270,6 +270,14 @@ void MCObjectStreamer::EmitGPRel64Value(const MCExpr *Value) {
   DF->getContents().resize(DF->getContents().size() + 8, 0);
 }
 
+void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue,
+                                unsigned AddrSpace) {
+  assert(AddrSpace == 0 && "Address space must be 0!");
+  // FIXME: A MCFillFragment would be more memory efficient but MCExpr has
+  //        problems evaluating expressions across multiple fragments.
+  getOrCreateDataFragment()->getContents().append(NumBytes, FillValue);
+}
+
 void MCObjectStreamer::FinishImpl() {
   // Dump out the dwarf file & directory tables and line tables.
   const MCSymbol *LineSectionSymbol = NULL;