Simplify ICF::run(). NFC.

[ruiu]

Summary

Simplify ICF::run(). NFC.

lld/ELF/ICF.cpp

template <class ELFT> void ICF<ELFT>::run() {
   } while (Repeat);
 
   log("ICF needed " + Twine(Cnt) + " iterations");
 
   // Merge sections by the equivalence class.
   forEachClassRange(0, Sections.size(), [&](size_t Begin, size_t End) {
     if (End - Begin == 1)
       return;
-    InputSection *Target = nullptr;
-    bool SeenUnique = false, Replaced = false;
-    for (size_t I = Begin; I < End; ++I) {
+
+    bool SeenUnique = Sections[Begin]->KeepUnique;
+    bool Replaced = false;
+
+    for (size_t I = Begin + 1; I < End; ++I) {
       // We aren't allowed to merge two KeepUnique sections as this would break
       // the guarantees provided by --keep-unique and --icf=safe, but there's
       // no reason why we can't merge a non-KeepUnique section with a KeepUnique
       // section. We implement this by only considering the first KeepUnique
       // section in the equivalence class for merging. If we see any more
       // KeepUnique sections, we ignore them.
       if (Sections[I]->KeepUnique) {
         if (SeenUnique)
           continue;
         SeenUnique = true;
       }
-      if (!Target) {
-        Target = Sections[I];
-        continue;
-      }
+
       if (!Replaced)
-        print("selected section " + toString(Target));
+        print("selected section " + toString(Sections[Begin]));
       print("  removing identical section " + toString(Sections[I]));
-      Target->replace(Sections[I]);
+      Sections[Begin]->replace(Sections[I]);
       Replaced = true;
 
       // At this point we know sections merged are fully identical and hence
       // we want to remove duplicate implicit dependencies such as link order
       // and relocation sections.
       for (InputSection *IS : Sections[I]->DependentSections)
         IS->Live = false;
     }