[ELF] Move a computeIsPreemptible() pass into ICF. NFC

[MaskRay]

Summary

Address post-commit review for D71163.

[ruiu]

LGTM

lld/ELF/Driver.cpp

for (BaseCommand *base : script->sectionCommands)
     if (auto *sec = dyn_cast<OutputSection>(base))
       sec->finalizeInputSections();
   llvm::erase_if(inputSections,
                  [](InputSectionBase *s) { return isa<MergeInputSection>(s); });
 
   // Two input sections with different output sections should not be folded.
   // ICF runs after processSectionCommands() so that we know the output sections.
   if (config->icf != ICFLevel::None) {
-    // Compute isPreemptible early to be used by ICF. We may add more symbols
-    // later, so this loop cannot be merged with the later computeIsPreemptible
-    // pass which is used by scanRelocations().
-    for (Symbol *sym : symtab->symbols())
-      sym->isPreemptible = computeIsPreemptible(*sym);
     findKeepUniqueSections<ELFT>(args);
     doIcf<ELFT>();
   }
 
   // Read the callgraph now that we know what was gced or icfed
   if (config->callGraphProfileSort) {
     if (auto *arg = args.getLastArg(OPT_call_graph_ordering_file))
       if (Optional<MemoryBufferRef> buffer = readFile(arg->getValue()))

lld/ELF/ICF.cpp

 
 static void print(const Twine &s) {
   if (config->printIcfSections)
     message(s);
 }
 
 // The main function of ICF.
 template <class ELFT> void ICF<ELFT>::run() {
+  // Compute isPreemptible early. We may add more symbols later, so this loop
+  // cannot be merged with the later computeIsPreemptible() pass which is used
+  // by scanRelocations().
+  for (Symbol *sym : symtab->symbols())
+    sym->isPreemptible = computeIsPreemptible(*sym);
+
   // Collect sections to merge.
   for (InputSectionBase *sec : inputSections) {
     auto *s = cast<InputSection>(sec);
     if (isEligible(s))
       sections.push_back(s);
   }
 
   // Initially, we use hash values to partition sections.