MCSymbolELF: Migrate away from classof

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

Author: MaskRay

llvm/include/llvm/MC/MCContext.h

@@ -392,6 +392,7 @@ class MCContext {
   Environment getObjectFileType() const { return Env; }
   bool isELF() const { return Env == IsELF; }
   bool isMachO() const { return Env == IsMachO; }
+  bool isXCOFF() const { return Env == IsXCOFF; }
 
   const StringRef &getSwift5ReflectionSegmentName() const {
     return Swift5ReflectionSegmentName;

llvm/lib/MC/MCObjectFileInfo.cpp

@@ -1135,9 +1135,10 @@ MCObjectFileInfo::getCallGraphSection(const MCSection &TextSec) const {
     Flags |= ELF::SHF_GROUP;
   }
 
-  return Ctx->getELFSection(".callgraph", ELF::SHT_PROGBITS, Flags, 0,
-                            GroupName, true, ElfSec.getUniqueID(),
-                            cast<MCSymbolELF>(TextSec.getBeginSymbol()));
+  return Ctx->getELFSection(
+      ".callgraph", ELF::SHT_PROGBITS, Flags, 0, GroupName, true,
+      ElfSec.getUniqueID(),
+      static_cast<const MCSymbolELF *>(TextSec.getBeginSymbol()));
 }
 
 MCSection *
@@ -1154,9 +1155,10 @@ MCObjectFileInfo::getStackSizesSection(const MCSection &TextSec) const {
     Flags |= ELF::SHF_GROUP;
   }
 
-  return Ctx->getELFSection(".stack_sizes", ELF::SHT_PROGBITS, Flags, 0,
-                            GroupName, true, ElfSec.getUniqueID(),
-                            cast<MCSymbolELF>(TextSec.getBeginSymbol()));
+  return Ctx->getELFSection(
+      ".stack_sizes", ELF::SHT_PROGBITS, Flags, 0, GroupName, true,
+      ElfSec.getUniqueID(),
+      static_cast<const MCSymbolELF *>(TextSec.getBeginSymbol()));
 }
 
 MCSection *
@@ -1174,9 +1176,10 @@ MCObjectFileInfo::getBBAddrMapSection(const MCSection &TextSec) const {
 
   // Use the text section's begin symbol and unique ID to create a separate
   // .llvm_bb_addr_map section associated with every unique text section.
-  return Ctx->getELFSection(".llvm_bb_addr_map", ELF::SHT_LLVM_BB_ADDR_MAP,
-                            Flags, 0, GroupName, true, ElfSec.getUniqueID(),
-                            cast<MCSymbolELF>(TextSec.getBeginSymbol()));
+  return Ctx->getELFSection(
+      ".llvm_bb_addr_map", ELF::SHT_LLVM_BB_ADDR_MAP, Flags, 0, GroupName, true,
+      ElfSec.getUniqueID(),
+      static_cast<const MCSymbolELF *>(TextSec.getBeginSymbol()));
 }
 
 MCSection *
@@ -1192,10 +1195,10 @@ MCObjectFileInfo::getKCFITrapSection(const MCSection &TextSec) const {
     Flags |= ELF::SHF_GROUP;
   }
 
-  return Ctx->getELFSection(".kcfi_traps", ELF::SHT_PROGBITS, Flags, 0,
-                            GroupName,
-                            /*IsComdat=*/true, ElfSec.getUniqueID(),
-                            cast<MCSymbolELF>(TextSec.getBeginSymbol()));
+  return Ctx->getELFSection(
+      ".kcfi_traps", ELF::SHT_PROGBITS, Flags, 0, GroupName,
+      /*IsComdat=*/true, ElfSec.getUniqueID(),
+      static_cast<const MCSymbolELF *>(TextSec.getBeginSymbol()));
 }
 
 MCSection *
@@ -1211,9 +1214,10 @@ MCObjectFileInfo::getPseudoProbeSection(const MCSection &TextSec) const {
     Flags |= ELF::SHF_GROUP;
   }
 
-  return Ctx->getELFSection(PseudoProbeSection->getName(), ELF::SHT_PROGBITS,
-                            Flags, 0, GroupName, true, ElfSec.getUniqueID(),
-                            cast<MCSymbolELF>(TextSec.getBeginSymbol()));
+  return Ctx->getELFSection(
+      PseudoProbeSection->getName(), ELF::SHT_PROGBITS, Flags, 0, GroupName,
+      true, ElfSec.getUniqueID(),
+      static_cast<const MCSymbolELF *>(TextSec.getBeginSymbol()));
 }
 
 MCSection *
@@ -1261,7 +1265,7 @@ MCSection *MCObjectFileInfo::getPCSection(StringRef Name,
     GroupName = Group->getName();
     Flags |= ELF::SHF_GROUP;
   }
-  return Ctx->getELFSection(Name, ELF::SHT_PROGBITS, Flags, 0, GroupName, true,
-                            ElfSec.getUniqueID(),
-                            cast<MCSymbolELF>(TextSec->getBeginSymbol()));
+  return Ctx->getELFSection(
+      Name, ELF::SHT_PROGBITS, Flags, 0, GroupName, true, ElfSec.getUniqueID(),
+      static_cast<const MCSymbolELF *>(TextSec->getBeginSymbol()));
 }

llvm/lib/MC/MCParser/ELFAsmParser.cpp

@@ -200,7 +200,7 @@ bool ELFAsmParser::parseDirectiveSize(StringRef, SMLoc) {
   StringRef Name;
   if (getParser().parseIdentifier(Name))
     return TokError("expected identifier");
-  MCSymbolELF *Sym = cast<MCSymbolELF>(getContext().getOrCreateSymbol(Name));
+  auto *Sym = static_cast<MCSymbolELF *>(getContext().getOrCreateSymbol(Name));
 
   if (getLexer().isNot(AsmToken::Comma))
     return TokError("expected comma");
@@ -466,7 +466,7 @@ bool ELFAsmParser::parseLinkedToSym(MCSymbolELF *&LinkedToSym) {
     }
     return TokError("invalid linked-to symbol");
   }
-  LinkedToSym = dyn_cast_or_null<MCSymbolELF>(getContext().lookupSymbol(Name));
+  LinkedToSym = static_cast<MCSymbolELF *>(getContext().lookupSymbol(Name));
   if (!LinkedToSym || !LinkedToSym->isInSection())
     return Error(StartLoc, "linked-to symbol is not in a section: " + Name);
   return false;

llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp

@@ -488,7 +488,8 @@ bool AArch64ELFObjectWriter::needsRelocateWithSymbol(const MCValue &Val,
   // this global needs to be tagged. In addition, the linker needs to know
   // whether to emit a special addend when relocating `end` symbols, and this
   // can only be determined by the attributes of the symbol itself.
-  if (Val.getAddSym() && cast<MCSymbolELF>(Val.getAddSym())->isMemtag())
+  if (Val.getAddSym() &&
+      static_cast<const MCSymbolELF *>(Val.getAddSym())->isMemtag())
     return true;
 
   if ((Val.getSpecifier() & AArch64::S_GOT) == AArch64::S_GOT)

llvm/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp

@@ -450,6 +450,7 @@ bool MipsELFObjectWriter::needsRelocateWithSymbol(const MCValue &V,
            needsRelocateWithSymbol(V, (Type >> 8) & 0xff) ||
            needsRelocateWithSymbol(V, (Type >> 16) & 0xff);
 
+  auto *Sym = static_cast<const MCSymbolELF *>(V.getAddSym());
   switch (Type) {
   default:
     errs() << Type << "\n";
@@ -481,7 +482,7 @@ bool MipsELFObjectWriter::needsRelocateWithSymbol(const MCValue &V,
     // FIXME: It should be safe to return false for the STO_MIPS_MICROMIPS but
     //        we neglect to handle the adjustment to the LSB of the addend that
     //        it causes in applyFixup() and similar.
-    if (cast<MCSymbolELF>(V.getAddSym())->getOther() & ELF::STO_MIPS_MICROMIPS)
+    if (Sym->getOther() & ELF::STO_MIPS_MICROMIPS)
       return true;
     return false;
 
@@ -492,7 +493,7 @@ bool MipsELFObjectWriter::needsRelocateWithSymbol(const MCValue &V,
   case ELF::R_MIPS_16:
   case ELF::R_MIPS_32:
   case ELF::R_MIPS_GPREL32:
-    if (cast<MCSymbolELF>(V.getAddSym())->getOther() & ELF::STO_MIPS_MICROMIPS)
+    if (Sym->getOther() & ELF::STO_MIPS_MICROMIPS)
       return true;
     [[fallthrough]];
   case ELF::R_MIPS_26:

llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp

@@ -13,6 +13,7 @@
 #include "llvm/BinaryFormat/MachO.h"
 #include "llvm/MC/MCAsmBackend.h"
 #include "llvm/MC/MCAssembler.h"
+#include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCELFObjectWriter.h"
 #include "llvm/MC/MCMachObjectWriter.h"
 #include "llvm/MC/MCObjectWriter.h"
@@ -112,14 +113,15 @@ class PPCAsmBackend : public MCAsmBackend {
       // to resolve the fixup directly.  Emit a relocation and leave
       // resolution of the final target address to the linker.
       if (const auto *A = Target.getAddSym()) {
-        if (const auto *S = dyn_cast<MCSymbolELF>(A)) {
+        if (getContext().isELF()) {
           // The "other" values are stored in the last 6 bits of the second
           // byte. The traditional defines for STO values assume the full byte
           // and thus the shift to pack it.
-          unsigned Other = S->getOther() << 2;
+          unsigned Other = static_cast<const MCSymbolELF *>(A)->getOther() << 2;
           if ((Other & ELF::STO_PPC64_LOCAL_MASK) != 0)
             return true;
-        } else if (const auto *S = dyn_cast<MCSymbolXCOFF>(A)) {
+        } else if (getContext().isXCOFF()) {
+          auto *S = static_cast<const MCSymbolXCOFF *>(A);
           return !Target.isAbsolute() && S->isExternal() &&
                  S->getStorageClass() == XCOFF::C_WEAKEXT;
         }