[llvm-objcopy][NFC] Add a helper method RelocationSectionBase::getPrefix()

[ikudrin]

Summary

Refactor handleArgs() to use that method.

[MaskRay]

Thanks!

[jhenderson]

LGTM, with one suggestion.

llvm/tools/llvm-objcopy/ELF/Object.h

748

Perhaps getNamePrefix for complete clarity on the function's purpose.

llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp

for (SectionBase &Sec : Obj.sections()) {
         // For example, if we rename .text to .prefix.text, we also rename
         // .rel.text to .rel.prefix.text.
         //
         // Dynamic relocation sections (SHT_REL[A] with SHF_ALLOC) are handled
         // above, e.g., .rela.plt is renamed to .prefix.rela.plt, not
         // .rela.prefix.plt since GNU objcopy does so.
         const SectionBase *TargetSec = RelocSec->getSection();
         if (TargetSec && (TargetSec->Flags & SHF_ALLOC)) {
-          StringRef prefix;
-          switch (Sec.Type) {
-          case SHT_REL:
-            prefix = ".rel";
-            break;
-          case SHT_RELA:
-            prefix = ".rela";
-            break;
-          default:
-            llvm_unreachable("not a relocation section");
-          }
-
           // If the relocation section comes *after* the target section, we
           // don't add Config.AllocSectionsPrefix because we've already added
           // the prefix to TargetSec->Name. Otherwise, if the relocation
           // section comes *before* the target section, we add the prefix.
           if (PrefixedSections.count(TargetSec))
-            Sec.Name = (prefix + TargetSec->Name).str();
+            Sec.Name = (RelocSec->getNamePrefix() + TargetSec->Name).str();
           else
-            Sec.Name =
-                (prefix + Config.AllocSectionsPrefix + TargetSec->Name).str();
+            Sec.Name = (RelocSec->getNamePrefix() + Config.AllocSectionsPrefix +
+                        TargetSec->Name)
+                           .str();
         }
       }
     }
   }
 
   if (!Config.SetSectionAlignment.empty()) {
     for (SectionBase &Sec : Obj.sections()) {
       auto I = Config.SetSectionAlignment.find(Sec.Name);

llvm/tools/llvm-objcopy/ELF/Object.h

 class RelocationSectionBase : public SectionBase {
 protected:
   SectionBase *SecToApplyRel = nullptr;
 
 public:
   const SectionBase *getSection() const { return SecToApplyRel; }
   void setSection(SectionBase *Sec) { SecToApplyRel = Sec; }
 
+  StringRef getNamePrefix() const;
+
   static bool classof(const SectionBase *S) {
     return S->OriginalType == ELF::SHT_REL || S->OriginalType == ELF::SHT_RELA;
   }
 };
 
 // Takes the symbol table type to use as a parameter so that we can deduplicate
 // that code between the two symbol table types.
 template <class SymTabType>

llvm/tools/llvm-objcopy/ELF/Object.cpp

 Error SymbolTableSection::accept(SectionVisitor &Visitor) const {
   return Visitor.visit(*this);
 }
 
 Error SymbolTableSection::accept(MutableSectionVisitor &Visitor) {
   return Visitor.visit(*this);
 }
 
+StringRef RelocationSectionBase::getNamePrefix() const {
+  switch (Type) {
+  case SHT_REL:
+    return ".rel";
+  case SHT_RELA:
+    return ".rela";
+  default:
+    llvm_unreachable("not a relocation section");
+  }
+}
+
 Error RelocationSection::removeSectionReferences(
     bool AllowBrokenLinks, function_ref<bool(const SectionBase *)> ToRemove) {
   if (ToRemove(Symbols)) {
     if (!AllowBrokenLinks)
       return createStringError(
           llvm::errc::invalid_argument,
           "symbol table '%s' cannot be removed because it is "
           "referenced by the relocation section '%s'",