[ELF] - Stop sorting input sections in createSections().

[grimar]

Summary

It does not seem that createSections() is a good place for applying
sorting.
We can do that inside sortSections(), which name looks more appropriate.
That also should help to following cleanup change: D39045.

[ruiu]

LGTM

ELF/Writer.cpp

1024

Remove {}

1033

Cmd -> Sec

ELF/OutputSections.cpp

uint64_t elf::getHeaderSize() {
   return Out::ElfHeader->Size + Out::ProgramHeaders->Size;
 }
 
 bool OutputSection::classof(const BaseCommand *C) {
   return C->Kind == OutputSectionKind;
 }
 
 void OutputSection::sort(std::function<int(InputSectionBase *S)> Order) {
+  assert(Live);
   assert(SectionCommands.size() == 1);
   sortByOrder(cast<InputSectionDescription>(SectionCommands[0])->Sections,
               Order);
 }
 
 // Fill [Buf, Buf + Size) with Filler.
 // This is used for linker script "=fillexp" command.
 static void fill(uint8_t *Buf, size_t Size, uint32_t Filler) {

ELF/Writer.cpp

 private:
   void createSyntheticSections();
   void copyLocalSymbols();
   void addSectionSymbols();
   void addReservedSymbols();
   void createSections();
   void forEachRelSec(std::function<void(InputSectionBase &)> Fn);
   void sortSections();
+  void sortInputSections();
   void finalizeSections();
   void addPredefinedSections();
   void setReservedSymbolSections();
 
   std::vector<PhdrEntry *> createPhdrs();
   void removeEmptyPTLoad();
   void addPtArmExid(std::vector<PhdrEntry *> &Phdrs);
   void assignFileOffsets();
template <class ELFT> void Writer<ELFT>::addReservedSymbols() {
   ElfSym::End1 = Add("end", -1);
   ElfSym::End2 = Add("_end", -1);
   ElfSym::Etext1 = Add("etext", -1);
   ElfSym::Etext2 = Add("_etext", -1);
   ElfSym::Edata1 = Add("edata", -1);
   ElfSym::Edata2 = Add("_edata", -1);
 }
 
-// Sort input sections by section name suffixes for
-// __attribute__((init_priority(N))).
-static void sortInitFini(OutputSection *Cmd) {
-  if (Cmd)
-    Cmd->sortInitFini();
-}
-
-// Sort input sections by the special rule for .ctors and .dtors.
-static void sortCtorsDtors(OutputSection *Cmd) {
-  if (Cmd)
-    Cmd->sortCtorsDtors();
-}
-
-// Sort input sections using the list provided by --symbol-ordering-file.
-static void sortBySymbolsOrder() {
-  if (Config->SymbolOrderingFile.empty())
-    return;
-
-  // Sort sections by priority.
-  DenseMap<SectionBase *, int> SectionOrder = buildSectionOrder();
-  for (BaseCommand *Base : Script->SectionCommands)
-    if (auto *Sec = dyn_cast<OutputSection>(Base))
-      Sec->sort([&](InputSectionBase *S) { return SectionOrder.lookup(S); });
-}
-
 template <class ELFT>
 void Writer<ELFT>::forEachRelSec(std::function<void(InputSectionBase &)> Fn) {
   // Scan all relocations. Each relocation goes through a series
   // of tests to determine if it needs special treatment, such as
   // creating GOT, PLT, copy relocations, etc.
   // Note that relocations for non-alloc sections are directly
   // processed by InputSection::relocateNonAlloc.
   for (InputSectionBase *IS : InputSections)
if (IS && IS->Live)
       if (OutputSection *Sec =
               Factory.addInputSec(IS, getOutputSectionName(IS->Name)))
         Vec.push_back(Sec);
 
   Script->SectionCommands.insert(Script->SectionCommands.begin(), Vec.begin(),
                                  Vec.end());
 
   Script->fabricateDefaultCommands();
-  sortBySymbolsOrder();
-  sortInitFini(findSection(".init_array"));
-  sortInitFini(findSection(".fini_array"));
-  sortCtorsDtors(findSection(".ctors"));
-  sortCtorsDtors(findSection(".dtors"));
 }
 
 // This function generates assignments for predefined symbols (e.g. _end or
 // _etext) and inserts them into the commands sequence to be processed at the
 // appropriate time. This ensures that the value is going to be correct by the
 // time any references to these symbols are processed and is equivalent to
 // defining these symbols explicitly in the linker script.
 template <class ELFT> void Writer<ELFT>::setReservedSymbolSections() {
findOrphanPos(std::vector<BaseCommand *>::iterator B,
   if (NextSec == E)
     return E;
 
   while (I != E && shouldSkip(*I))
     ++I;
   return I;
 }
 
+// If no layout was provided by linker script, we want to apply default
+// sorting for special input sections and handle --symbol-ordering-file.
+template <class ELFT> void Writer<ELFT>::sortInputSections() {
+  assert(!Script->HasSectionsCommand);
+
+  // Sort input sections by priority using the list provided
+  // by --symbol-ordering-file.
+  DenseMap<SectionBase *, int> Order = buildSectionOrder();
+  if (!Order.empty()) {
+    for (BaseCommand *Base : Script->SectionCommands)
+      if (auto *Sec = dyn_cast<OutputSection>(Base))
+        if (Sec->Live)
+          Sec->sort([&](InputSectionBase *S) { return Order.lookup(S); });
+  }
+
+  // Sort input sections by section name suffixes for
+  // __attribute__((init_priority(N))).
+  if (OutputSection *Cmd = findSection(".init_array"))
+    Cmd->sortInitFini();
+  if (OutputSection *Cmd = findSection(".fini_array"))
+    Cmd->sortInitFini();
+
+  // Sort input sections by the special rule for .ctors and .dtors.
+  if (OutputSection *Cmd = findSection(".ctors"))
+    Cmd->sortCtorsDtors();
+  if (OutputSection *Cmd = findSection(".dtors"))
+    Cmd->sortCtorsDtors();
+}
+
 template <class ELFT> void Writer<ELFT>::sortSections() {
   Script->adjustSectionsBeforeSorting();
 
   // Don't sort if using -r. It is not necessary and we want to preserve the
   // relative order for SHF_LINK_ORDER sections.
   if (Config->Relocatable)
     return;
 
   for (BaseCommand *Base : Script->SectionCommands)
     if (auto *Sec = dyn_cast<OutputSection>(Base))
       Sec->SortRank = getSectionRank(Sec);
 
   if (!Script->HasSectionsCommand) {
-    // We know that all the OutputSections are contiguous in
-    // this case.
+    sortInputSections();
+
+    // We know that all the OutputSections are contiguous in this case.
     auto E = Script->SectionCommands.end();
     auto I = Script->SectionCommands.begin();
     auto IsSection = [](BaseCommand *Base) { return isa<OutputSection>(Base); };
     I = std::find_if(I, E, IsSection);
     E = std::find_if(llvm::make_reverse_iterator(E),
                      llvm::make_reverse_iterator(I), IsSection)
             .base();
     std::stable_sort(I, E, compareSections);