XCOFF: Simplify R_REF and remove a MCFragment::addFixup use

Simplify the code added by https://reviews.llvm.org/D144356

Author: MaskRay

llvm/lib/MC/MCXCOFFStreamer.cpp

@@ -103,16 +103,8 @@ void MCXCOFFStreamer::emitXCOFFSymbolLinkageWithVisibility(
 void MCXCOFFStreamer::emitXCOFFRefDirective(const MCSymbol *Symbol) {
   // Add a Fixup here to later record a relocation of type R_REF to prevent the
   // ref symbol from being garbage collected (by the binder).
-  MCFragment *DF = getCurrentFragment();
-  const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(Symbol, getContext());
-  std::optional<MCFixupKind> MaybeKind =
-      getAssembler().getBackend().getFixupKind("R_REF");
-  if (!MaybeKind)
-    report_fatal_error("failed to get fixup kind for R_REF relocation");
-
-  MCFixupKind Kind = *MaybeKind;
-  MCFixup Fixup = MCFixup::create(DF->getContents().size(), SRE, Kind);
-  DF->addFixup(Fixup);
+  addFixup(MCSymbolRefExpr::create(Symbol, getContext()),
+           XCOFF::RelocationType::R_REF);
 }
 
 void MCXCOFFStreamer::emitXCOFFRenameDirective(const MCSymbol *Name,

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

@@ -243,8 +243,6 @@ class XCOFFPPCAsmBackend : public PPCAsmBackend {
   createObjectTargetWriter() const override {
     return createPPCXCOFFObjectWriter(TT.isArch64Bit());
   }
-
-  std::optional<MCFixupKind> getFixupKind(StringRef Name) const override;
 };
 
 } // end anonymous namespace
@@ -279,13 +277,6 @@ ELFPPCAsmBackend::getFixupKind(StringRef Name) const {
   return std::nullopt;
 }
 
-std::optional<MCFixupKind>
-XCOFFPPCAsmBackend::getFixupKind(StringRef Name) const {
-  return StringSwitch<std::optional<MCFixupKind>>(Name)
-      .Case("R_REF", PPC::fixup_ppc_nofixup)
-      .Default(std::nullopt);
-}
-
 MCAsmBackend *llvm::createPPCAsmBackend(const Target &T,
                                         const MCSubtargetInfo &STI,
                                         const MCRegisterInfo &MRI,

llvm/lib/Target/PowerPC/MCTargetDesc/PPCFixupKinds.h

@@ -48,8 +48,7 @@ enum Fixups {
 
   /// Not a true fixup, but ties a symbol to a call to __tls_get_addr for the
   /// TLS general and local dynamic models, or inserts the thread-pointer
-  /// register number. It can also be used to tie the ref symbol to prevent it
-  /// from being garbage collected on AIX.
+  /// register number.
   fixup_ppc_nofixup,
 
   /// A 16-bit fixup corresponding to lo16(_foo) with implied 3 zero bits for

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

@@ -56,6 +56,8 @@ std::pair<uint8_t, uint8_t> PPCXCOFFObjectWriter::getRelocTypeAndSignSize(
   switch ((unsigned)Fixup.getKind()) {
   default:
     report_fatal_error("Unimplemented fixup kind.");
+  case XCOFF::RelocationType::R_REF:
+    return {XCOFF::RelocationType::R_REF, 0};
   case PPC::fixup_ppc_half16: {
     const uint8_t SignAndSizeForHalf16 = EncodedSignednessIndicator | 15;
     switch (Specifier) {
@@ -96,12 +98,6 @@ std::pair<uint8_t, uint8_t> PPCXCOFFObjectWriter::getRelocTypeAndSignSize(
     return {XCOFF::RelocationType::R_RBR, EncodedSignednessIndicator | 25};
   case PPC::fixup_ppc_br24abs:
     return {XCOFF::RelocationType::R_RBA, EncodedSignednessIndicator | 25};
-  case PPC::fixup_ppc_nofixup: {
-    if (Specifier == PPC::S_None)
-      return {XCOFF::RelocationType::R_REF, 0};
-    else
-      llvm_unreachable("Unsupported Modifier");
-  } break;
   case FK_Data_4:
   case FK_Data_8:
     const uint8_t SignAndSizeForFKData =