MCSectionCOFF: Remove classof

The object file format specific derived classes are used in context like
MCStreamer and MCObjectTargetWriter where the type is statically known.
We don't use isa/dyn_cast and we want to eliminate
MCSection::SectionVariant in the base class.

Author: MaskRay

llvm/include/llvm/MC/MCSectionCOFF.h

@@ -92,8 +92,6 @@ class MCSectionCOFF final : public MCSection {
   static bool isImplicitlyDiscardable(StringRef Name) {
     return Name.starts_with(".debug");
   }
-
-  static bool classof(const MCSection *S) { return S->getVariant() == SV_COFF; }
 };
 
 } // end namespace llvm

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -4221,10 +4221,11 @@ MCSymbol *AsmPrinter::GetCPISymbol(unsigned CPID) const {
       SectionKind Kind = CPE.getSectionKind(&DL);
       const Constant *C = CPE.Val.ConstVal;
       Align Alignment = CPE.Alignment;
-      if (const MCSectionCOFF *S = dyn_cast<MCSectionCOFF>(
-              getObjFileLowering().getSectionForConstant(DL, Kind, C,
-                                                         Alignment))) {
-        if (MCSymbol *Sym = S->getCOMDATSymbol()) {
+      auto *S =
+          getObjFileLowering().getSectionForConstant(DL, Kind, C, Alignment);
+      if (S && TM.getTargetTriple().isOSBinFormatCOFF()) {
+        if (MCSymbol *Sym =
+                static_cast<const MCSectionCOFF *>(S)->getCOMDATSymbol()) {
           if (Sym->isUndefined())
             OutStreamer->emitSymbolAttribute(Sym, MCSA_Global);
           return Sym;

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

@@ -1051,10 +1051,10 @@ void CodeViewDebug::switchToDebugSectionForSymbol(const MCSymbol *GVSym) {
   // comdat key. A section may be comdat because of -ffunction-sections or
   // because it is comdat in the IR.
   MCSectionCOFF *GVSec =
-      GVSym ? dyn_cast<MCSectionCOFF>(&GVSym->getSection()) : nullptr;
+      GVSym ? static_cast<MCSectionCOFF *>(&GVSym->getSection()) : nullptr;
   const MCSymbol *KeySym = GVSec ? GVSec->getCOMDATSymbol() : nullptr;
 
-  MCSectionCOFF *DebugSec = cast<MCSectionCOFF>(
+  auto *DebugSec = static_cast<MCSectionCOFF *>(
       CompilerInfoAsm->getObjFileLowering().getCOFFDebugSymbolsSection());
   DebugSec = OS.getContext().getAssociativeCOFFSection(DebugSec, KeySym);
 

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -2054,14 +2054,14 @@ MCSection *TargetLoweringObjectFileCOFF::getStaticCtorSection(
     unsigned Priority, const MCSymbol *KeySym) const {
   return getCOFFStaticStructorSection(
       getContext(), getContext().getTargetTriple(), true, Priority, KeySym,
-      cast<MCSectionCOFF>(StaticCtorSection));
+      static_cast<MCSectionCOFF *>(StaticCtorSection));
 }
 
 MCSection *TargetLoweringObjectFileCOFF::getStaticDtorSection(
     unsigned Priority, const MCSymbol *KeySym) const {
   return getCOFFStaticStructorSection(
       getContext(), getContext().getTargetTriple(), false, Priority, KeySym,
-      cast<MCSectionCOFF>(StaticDtorSection));
+      static_cast<MCSectionCOFF *>(StaticDtorSection));
 }
 
 const MCExpr *TargetLoweringObjectFileCOFF::lowerRelativeReference(

llvm/lib/MC/MCContext.cpp

@@ -782,8 +782,8 @@ MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
     if (Selection != COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE &&
         COMDATSymbol->isDefined() &&
         (!COMDATSymbol->isInSection() ||
-         cast<MCSectionCOFF>(COMDATSymbol->getSection()).getCOMDATSymbol() !=
-             COMDATSymbol))
+         static_cast<const MCSectionCOFF &>(COMDATSymbol->getSection())
+                 .getCOMDATSymbol() != COMDATSymbol))
       reportError(SMLoc(), "invalid symbol redefinition");
   }
 

llvm/lib/MC/MCStreamer.cpp

@@ -838,8 +838,8 @@ static MCSection *getWinCFISection(MCContext &Context, unsigned *NextWinCFIID,
   if (TextSec == Context.getObjectFileInfo()->getTextSection())
     return MainCFISec;
 
-  const auto *TextSecCOFF = cast<MCSectionCOFF>(TextSec);
-  auto *MainCFISecCOFF = cast<MCSectionCOFF>(MainCFISec);
+  const auto *TextSecCOFF = static_cast<const MCSectionCOFF *>(TextSec);
+  auto *MainCFISecCOFF = static_cast<MCSectionCOFF *>(MainCFISec);
   unsigned UniqueID = TextSecCOFF->getOrAssignWinCFISectionID(NextWinCFIID);
 
   // If this section is COMDAT, this unwind section should be COMDAT associative

llvm/lib/MC/MCWinCOFFStreamer.cpp

@@ -157,7 +157,8 @@ void MCWinCOFFStreamer::changeSection(MCSection *Section, uint32_t Subsection) {
   // Ensure that the first and the second symbols relative to the section are
   // the section symbol and the COMDAT symbol.
   getAssembler().registerSymbol(*Section->getBeginSymbol());
-  if (auto *Sym = cast<MCSectionCOFF>(Section)->getCOMDATSymbol())
+  if (auto *Sym =
+          static_cast<const MCSectionCOFF *>(Section)->getCOMDATSymbol())
     getAssembler().registerSymbol(*Sym);
 }
 

llvm/lib/MC/WinCOFFObjectWriter.cpp

@@ -373,7 +373,7 @@ void WinCOFFWriter::defineSymbol(const MCSymbol &MCSym) {
   COFFSection *Sec = nullptr;
   MCSectionCOFF *MCSec = nullptr;
   if (Base && Base->getFragment()) {
-    MCSec = cast<MCSectionCOFF>(Base->getFragment()->getParent());
+    MCSec = static_cast<MCSectionCOFF *>(Base->getFragment()->getParent());
     Sec = SectionMap[MCSec];
   }
 
@@ -1057,7 +1057,8 @@ uint64_t WinCOFFWriter::writeObject() {
       continue;
     }
 
-    const auto *AssocMCSec = cast<MCSectionCOFF>(&AssocMCSym->getSection());
+    const auto *AssocMCSec =
+        static_cast<const MCSectionCOFF *>(&AssocMCSym->getSection());
     assert(SectionMap.count(AssocMCSec));
     COFFSection *AssocSec = SectionMap[AssocMCSec];