[llvm] 85f0070 - MCSymbolMachO: Migrate away from classof

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2025-08-03T17:48:50-07:00
New Revision: 85f00707dd651d6c09c25aab882dc568a1f32f52

URL: https://github.com/llvm/llvm-project/commit/85f00707dd651d6c09c25aab882dc568a1f32f52
DIFF: https://github.com/llvm/llvm-project/commit/85f00707dd651d6c09c25aab882dc568a1f32f52.diff

LOG: MCSymbolMachO: 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.

Added: 
    

Modified: 
    llvm/lib/MC/MCMachOStreamer.cpp
    llvm/lib/MC/MachObjectWriter.cpp
    llvm/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/MC/MCMachOStreamer.cpp b/llvm/lib/MC/MCMachOStreamer.cpp
index a2145133566dc..c850ed9fec26b 100644
--- a/llvm/lib/MC/MCMachOStreamer.cpp
+++ b/llvm/lib/MC/MCMachOStreamer.cpp
@@ -147,7 +147,7 @@ void MCMachOStreamer::changeSection(MCSection *Section, uint32_t Subsection) {
 
 void MCMachOStreamer::emitEHSymAttributes(const MCSymbol *Symbol,
                                           MCSymbol *EHSymbol) {
-  auto *Sym = cast<MCSymbolMachO>(Symbol);
+  auto *Sym = static_cast<const MCSymbolMachO *>(Symbol);
   getAssembler().registerSymbol(*Symbol);
   if (Symbol->isExternal())
     emitSymbolAttribute(EHSymbol, MCSA_Global);
@@ -172,7 +172,7 @@ void MCMachOStreamer::emitLabel(MCSymbol *Symbol, SMLoc Loc) {
   //
   // FIXME: Cleanup this code, these bits should be emitted based on semantic
   // properties, not on the order of definition, etc.
-  cast<MCSymbolMachO>(Symbol)->clearReferenceType();
+  static_cast<MCSymbolMachO *>(Symbol)->clearReferenceType();
 }
 
 void MCMachOStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
@@ -182,7 +182,7 @@ void MCMachOStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
     if (const auto *SymA = Res.getAddSym()) {
       if (!Res.getSubSym() &&
           (SymA->getName().empty() || Res.getConstant() != 0))
-        cast<MCSymbolMachO>(Symbol)->setAltEntry();
+        static_cast<MCSymbolMachO *>(Symbol)->setAltEntry();
     }
   }
   MCObjectStreamer::emitAssignment(Symbol, Value);
@@ -256,7 +256,7 @@ void MCMachOStreamer::emitDarwinTargetVariantBuildVersion(
 
 bool MCMachOStreamer::emitSymbolAttribute(MCSymbol *Sym,
                                           MCSymbolAttr Attribute) {
-  MCSymbolMachO *Symbol = cast<MCSymbolMachO>(Sym);
+  auto *Symbol = static_cast<MCSymbolMachO *>(Sym);
 
   // Indirect symbols are handled 
diff erently, to match how 'as' handles
   // them. This makes writing matching .o files easier.
@@ -367,7 +367,7 @@ bool MCMachOStreamer::emitSymbolAttribute(MCSymbol *Sym,
 void MCMachOStreamer::emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
   // Encode the 'desc' value into the lowest implementation defined bits.
   getAssembler().registerSymbol(*Symbol);
-  cast<MCSymbolMachO>(Symbol)->setDesc(DescValue);
+  static_cast<MCSymbolMachO *>(Symbol)->setDesc(DescValue);
 }
 
 void MCMachOStreamer::emitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
@@ -430,7 +430,7 @@ void MCMachOStreamer::finishImpl() {
   // defining symbols.
   DenseMap<const MCFragment *, const MCSymbol *> DefiningSymbolMap;
   for (const MCSymbol &Symbol : getAssembler().symbols()) {
-    auto &Sym = cast<MCSymbolMachO>(Symbol);
+    auto &Sym = static_cast<const MCSymbolMachO &>(Symbol);
     if (Sym.isSymbolLinkerVisible() && Sym.isInSection() && !Sym.isVariable() &&
         !Sym.isAltEntry()) {
       // An atom defining symbol should never be internal to a fragment.

diff  --git a/llvm/lib/MC/MachObjectWriter.cpp b/llvm/lib/MC/MachObjectWriter.cpp
index e87696a93cddd..bcdc0012ebf98 100644
--- a/llvm/lib/MC/MachObjectWriter.cpp
+++ b/llvm/lib/MC/MachObjectWriter.cpp
@@ -72,7 +72,7 @@ bool MachObjectWriter::doesSymbolRequireExternRelocation(const MCSymbol &S) {
 
   // References to weak definitions require external relocation entries; the
   // definition may not always be the one in the same object file.
-  if (cast<MCSymbolMachO>(S).isWeakDefinition())
+  if (static_cast<const MCSymbolMachO &>(S).isWeakDefinition())
     return true;
 
   // Otherwise, we can use an internal relocation.
@@ -383,15 +383,16 @@ const MCSymbol &MachObjectWriter::findAliasedSymbol(const MCSymbol &Sym) const {
 }
 
 void MachObjectWriter::writeNlist(MachSymbolData &MSD, const MCAssembler &Asm) {
-  const MCSymbol *Symbol = MSD.Symbol;
-  const auto &Data = cast<MCSymbolMachO>(*Symbol);
-  const MCSymbol *AliasedSymbol = &findAliasedSymbol(*Symbol);
+  auto *Symbol = static_cast<const MCSymbolMachO *>(MSD.Symbol);
+  const auto &Data = static_cast<const MCSymbolMachO &>(*Symbol);
+  auto *AliasedSymbol =
+      static_cast<const MCSymbolMachO *>(&findAliasedSymbol(*Symbol));
   uint8_t SectionIndex = MSD.SectionIndex;
   uint8_t Type = 0;
   uint64_t Address = 0;
   bool IsAlias = Symbol != AliasedSymbol;
 
-  const MCSymbol &OrigSymbol = *Symbol;
+  const MCSymbolMachO &OrigSymbol = *Symbol;
   MachSymbolData *AliaseeInfo;
   if (IsAlias) {
     AliaseeInfo = findSymbolData(*AliasedSymbol);
@@ -441,9 +442,8 @@ void MachObjectWriter::writeNlist(MachSymbolData &MSD, const MCAssembler &Asm) {
 
   // The Mach-O streamer uses the lowest 16-bits of the flags for the 'desc'
   // value.
-  bool EncodeAsAltEntry =
-    IsAlias && cast<MCSymbolMachO>(OrigSymbol).isAltEntry();
-  W.write<uint16_t>(cast<MCSymbolMachO>(Symbol)->getEncodedFlags(EncodeAsAltEntry));
+  bool EncodeAsAltEntry = IsAlias && OrigSymbol.isAltEntry();
+  W.write<uint16_t>(Symbol->getEncodedFlags(EncodeAsAltEntry));
   if (is64Bit())
     W.write<uint64_t>(Address);
   else
@@ -570,7 +570,8 @@ void MachObjectWriter::bindIndirectSymbols(MCAssembler &Asm) {
     //
     // FIXME: Do not hardcode.
     if (Asm.registerSymbol(*ISD.Symbol))
-      cast<MCSymbolMachO>(ISD.Symbol)->setReferenceTypeUndefinedLazy(true);
+      static_cast<MCSymbolMachO *>(ISD.Symbol)
+          ->setReferenceTypeUndefinedLazy(true);
   }
 }
 

diff  --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp
index 354de8fd7b4bb..8ee3a2d26a599 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp
@@ -505,7 +505,7 @@ class ARMTargetMachOStreamer : public ARMTargetStreamer {
     // Remember that the function is a thumb function. Fixup and relocation
     // values will need adjusted.
     getStreamer().getAssembler().setIsThumbFunc(Symbol);
-    cast<MCSymbolMachO>(Symbol)->setThumbFunc();
+    static_cast<MCSymbolMachO *>(Symbol)->setThumbFunc();
   }
 };
 } // namespace