[MC] Simplify Sec.getFragmentList().insert(Sec.begin(), F). NFC

Decrease the uses of getFragmentList() to make it easier to change the
fragment list representation.

Author: MaskRay

llvm/include/llvm/MC/MCSection.h

@@ -188,6 +188,8 @@ class MCSection {
   iterator end() { return Fragments.end(); }
   const_iterator end() const { return Fragments.end(); }
 
+  void addFragment(MCFragment &F) { Fragments.push_back(&F); }
+
   MCSection::iterator getSubsectionInsertionPoint(unsigned Subsection);
 
   void dump() const;

llvm/lib/MC/MCContext.cpp

@@ -498,7 +498,7 @@ MCSectionELF *MCContext::createELFSectionImpl(StringRef Section, unsigned Type,
                    R, LinkedToSym);
 
   auto *F = new MCDataFragment();
-  Ret->getFragmentList().insert(Ret->begin(), F);
+  Ret->addFragment(*F);
   F->setParent(Ret);
   R->setFragment(F);
 
@@ -772,7 +772,7 @@ MCSectionWasm *MCContext::getWasmSection(const Twine &Section, SectionKind Kind,
   Entry.second = Result;
 
   auto *F = new MCDataFragment();
-  Result->getFragmentList().insert(Result->begin(), F);
+  Result->addFragment(*F);
   F->setParent(Result);
   Begin->setFragment(F);
 
@@ -838,7 +838,7 @@ MCSectionXCOFF *MCContext::getXCOFFSection(
   Entry.second = Result;
 
   auto *F = new MCDataFragment();
-  Result->getFragmentList().insert(Result->begin(), F);
+  Result->addFragment(*F);
   F->setParent(Result);
 
   if (Begin)
@@ -861,7 +861,7 @@ MCSectionSPIRV *MCContext::getSPIRVSection() {
       MCSectionSPIRV(SectionKind::getText(), Begin);
 
   auto *F = new MCDataFragment();
-  Result->getFragmentList().insert(Result->begin(), F);
+  Result->addFragment(*F);
   F->setParent(Result);
 
   return Result;
@@ -884,7 +884,7 @@ MCSectionDXContainer *MCContext::getDXContainerSection(StringRef Section,
 
   // The first fragment will store the header
   auto *F = new MCDataFragment();
-  MapIt->second->getFragmentList().insert(MapIt->second->begin(), F);
+  MapIt->second->addFragment(*F);
   F->setParent(MapIt->second);
 
   return MapIt->second;

llvm/lib/MC/MCFragment.cpp

@@ -260,7 +260,7 @@ MCFragment::MCFragment(FragmentType Kind, bool HasInstructions,
     : Parent(Parent), Atom(nullptr), Offset(~UINT64_C(0)), LayoutOrder(0),
       Kind(Kind), IsBeingLaidOut(false), HasInstructions(HasInstructions) {
   if (Parent && !isa<MCDummyFragment>(*this))
-    Parent->getFragmentList().push_back(this);
+    Parent->addFragment(*this);
 }
 
 void MCFragment::destroy() {