[MC] switchSectionNoPrint: update CurFrag

To ensure that CurFrag->Parent and SectionStack.back() are in sync.

Author: MaskRay

llvm/include/llvm/MC/MCObjectStreamer.h

@@ -125,6 +125,7 @@ class MCObjectStreamer : public MCStreamer {
   void emitSLEB128Value(const MCExpr *Value) override;
   void emitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override;
   void changeSection(MCSection *Section, uint32_t Subsection = 0) override;
+  void switchSectionNoPrint(MCSection *Section) override;
   void emitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) override;
 
   /// Emit an instruction to a special fragment, because this instruction

llvm/include/llvm/MC/MCStreamer.h

@@ -433,15 +433,8 @@ class MCStreamer {
   virtual void switchSection(MCSection *Section, uint32_t Subsec = 0);
   bool switchSection(MCSection *Section, const MCExpr *);
 
-  /// Set the current section where code is being emitted to \p Section.
-  /// This is required to update CurSection. This version does not call
-  /// changeSection.
-  void switchSectionNoChange(MCSection *Section) {
-    assert(Section && "Cannot switch to a null section!");
-    MCSectionSubPair curSection = SectionStack.back().first;
-    SectionStack.back().second = curSection;
-    SectionStack.back().first = MCSectionSubPair(Section, 0);
-  }
+  /// Similar to switchSection, but does not print the section directive.
+  virtual void switchSectionNoPrint(MCSection *Section);
 
   /// Create the default sections and set the initial one.
   virtual void initSections(bool NoExecStack, const MCSubtargetInfo &STI);

llvm/lib/MC/MCAsmStreamer.cpp

@@ -2209,7 +2209,7 @@ void MCAsmStreamer::emitWinEHHandlerData(SMLoc Loc) {
 
   MCSection *TextSec = &CurFrame->Function->getSection();
   MCSection *XData = getAssociatedXDataSection(TextSec);
-  switchSectionNoChange(XData);
+  switchSectionNoPrint(XData);
 
   OS << "\t.seh_handlerdata";
   EmitEOL();
@@ -2626,7 +2626,7 @@ void MCAsmStreamer::doFinalizationAtSectionEnd(MCSection *Section) {
   if (MAI->usesDwarfFileAndLocDirectives())
     return;
 
-  switchSectionNoChange(Section);
+  switchSectionNoPrint(Section);
 
   MCSymbol *Sym = getCurrentSectionOnly()->getEndSymbol(getContext());
 

llvm/lib/MC/MCObjectStreamer.cpp

@@ -313,6 +313,11 @@ bool MCObjectStreamer::changeSectionImpl(MCSection *Section,
   return getAssembler().registerSection(*Section);
 }
 
+void MCObjectStreamer::switchSectionNoPrint(MCSection *Section) {
+  MCStreamer::switchSectionNoPrint(Section);
+  changeSection(Section, 0);
+}
+
 void MCObjectStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
   getAssembler().registerSymbol(*Symbol);
   MCStreamer::emitAssignment(Symbol, Value);

llvm/lib/MC/MCStreamer.cpp

@@ -1290,6 +1290,12 @@ bool MCStreamer::switchSection(MCSection *Section, const MCExpr *SubsecExpr) {
   return false;
 }
 
+void MCStreamer::switchSectionNoPrint(MCSection *Section) {
+  SectionStack.back().second = SectionStack.back().first;
+  SectionStack.back().first = MCSectionSubPair(Section, 0);
+  CurFrag = &Section->getDummyFragment();
+}
+
 MCSymbol *MCStreamer::endSection(MCSection *Section) {
   // TODO: keep track of the last subsection so that this symbol appears in the
   // correct place.