ELF: Remove a comparison against In.EhFrame. NFCI.

[pcc]

Summary

This won't work once we have multiple .eh_frame sections.

[MaskRay]

LG

lld/ELF/MapFile.cpp

109

Can Sec be const?

[pcc]

lld/ELF/MapFile.cpp

109

Yes, done.

lld/ELF/MapFile.cpp

 }
 
 // Print .eh_frame contents. Since the section consists of EhSectionPieces,
 // we need a specialized printer for that section.
 //
 // .eh_frame tend to contain a lot of section pieces that are contiguous
 // both in input file and output file. Such pieces are squashed before
 // being displayed to make output compact.
-static void printEhFrame(raw_ostream &OS, OutputSection *OSec) {
+static void printEhFrame(raw_ostream &OS, EhFrameSection *Sec) {
   std::vector<EhSectionPiece> Pieces;
 
   auto Add = [&](const EhSectionPiece &P) {
     // If P is adjacent to Last, squash the two.
     if (!Pieces.empty()) {
       EhSectionPiece &Last = Pieces.back();
       if (Last.Sec == P.Sec && Last.InputOff + Last.Size == P.InputOff &&
           Last.OutputOff + Last.Size == P.OutputOff) {
         Last.Size += P.Size;
         return;
       }
     }
     Pieces.push_back(P);
   };
 
   // Gather section pieces.
-  for (const CieRecord *Rec : In.EhFrame->getCieRecords()) {
+  for (const CieRecord *Rec : Sec->getCieRecords()) {
     Add(*Rec->Cie);
     for (const EhSectionPiece *Fde : Rec->Fdes)
       Add(*Fde);
   }
 
   // Print out section pieces.
+  OutputSection *OSec = Sec->getOutputSection();
   for (EhSectionPiece &P : Pieces) {
     writeHeader(OS, OSec->Addr + P.OutputOff, OSec->getLMA() + P.OutputOff,
                 P.Size, 1);
     OS << Indent8 << toString(P.Sec->File) << ":(" << P.Sec->Name << "+0x"
        << Twine::utohexstr(P.InputOff) + ")\n";
   }
 }
 
for (BaseCommand *Base : Script->SectionCommands) {
     OSec = cast<OutputSection>(Base);
     writeHeader(OS, OSec->Addr, OSec->getLMA(), OSec->Size, OSec->Alignment);
     OS << OSec->Name << '\n';
 
     // Dump symbols for each input section.
     for (BaseCommand *Base : OSec->SectionCommands) {
       if (auto *ISD = dyn_cast<InputSectionDescription>(Base)) {
         for (InputSection *IS : ISD->Sections) {
-          if (IS == In.EhFrame) {
-            printEhFrame(OS, OSec);
+          if (auto *EhSec = dyn_cast<EhFrameSection>(IS)) {
+            printEhFrame(OS, EhSec);
             continue;
           }
 
           writeHeader(OS, IS->getVA(0), OSec->getLMA() + IS->getOffset(0),
                       IS->getSize(), IS->Alignment);
           OS << Indent8 << toString(IS) << '\n';
           for (Symbol *Sym : SectionSyms[IS])
             OS << SymStr[Sym] << '\n';

lld/ELF/SyntheticSections.h

 class EhFrameSection final : public SyntheticSection {
 public:
   EhFrameSection();
   void writeTo(uint8_t *Buf) override;
   void finalizeContents() override;
   bool isNeeded() const override { return !Sections.empty(); }
   size_t getSize() const override { return Size; }
 
+  static bool classof(const SectionBase *D) {
+    return SyntheticSection::classof(D) && D->Name == ".eh_frame";
+  }
+
   template <class ELFT> void addSection(InputSectionBase *S);
 
   std::vector<EhInputSection *> Sections;
   size_t NumFdes = 0;
 
   struct FdeData {
     uint32_t PcRel;
     uint32_t FdeVARel;