[ELF] - Refactor of tls_index implementation for tls local dynamic model.

[grimar]

Summary

Patch contains the next 2 changes:

1. static variable Out<ELFT>::LocalModuleTlsIndexOffset moved to Out<ELFT>::Got. At fact there is no meaning for it to be separated from GOT class because at each place of using it anyways needs to call GOT`s getVA(). Also it is impossible to have that offset and not have GOT.

2. addLocalModuleTlsIndex -> addLocalModelTlsIndex (word "Module" changed to "Model"). Not sure was it a mistype or not but I think that update is closer to Urlich terminology.

[ruiu]

LGTM. Nice cleanup!

lld/trunk/ELF/InputSection.cpp

if (Offset == (uintX_t)-1)
       continue;
 
     uint8_t *BufLoc = Buf + Offset;
     uintX_t AddrLoc = OutSec->getVA() + Offset;
 
     if (Target->isTlsLocalDynamicReloc(Type) &&
         !Target->isTlsOptimized(Type, nullptr)) {
       Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc,
-                          Out<ELFT>::Got->getVA() +
-                              Out<ELFT>::LocalModuleTlsIndexOffset +
+                          Out<ELFT>::Got->getLocalTlsIndexVA() +
                               getAddend<ELFT>(RI));
       continue;
     }
 
     // Handle relocations for local symbols -- they never get
     // resolved so we don't allocate a SymbolBody.
     const Elf_Shdr *SymTab = File->getSymbolTable();
     if (SymIndex < SymTab->sh_info) {

lld/trunk/ELF/OutputSections.h

template <class ELFT> class GotSection final : public OutputSectionBase<ELFT> {
   typedef typename Base::uintX_t uintX_t;
 
 public:
   GotSection();
   void finalize() override;
   void writeTo(uint8_t *Buf) override;
   void addEntry(SymbolBody *Sym);
   void addDynTlsEntry(SymbolBody *Sym);
-  uint32_t addLocalModuleTlsIndex();
+  bool addLocalModelTlsIndex();
   bool empty() const { return Entries.empty(); }
   uintX_t getEntryAddr(const SymbolBody &B) const;
 
   // Returns the symbol which corresponds to the first entry of the global part
   // of GOT on MIPS platform. It is required to fill up MIPS-specific dynamic
   // table properties.
   // Returns nullptr if the global part is empty.
   const SymbolBody *getMipsFirstGlobalEntry() const;
 
   // Returns the number of entries in the local part of GOT including
   // the number of reserved entries. This method is MIPS-specific.
   unsigned getMipsLocalEntriesNum() const;
 
+  uint32_t getLocalTlsIndexVA() { return getVA() + LocalTlsIndexOff; }
+
 private:
   std::vector<const SymbolBody *> Entries;
+  uint32_t LocalTlsIndexOff = -1;
 };
 
 template <class ELFT>
 class GotPltSection final : public OutputSectionBase<ELFT> {
   typedef typename llvm::object::ELFFile<ELFT>::uintX_t uintX_t;
 
 public:
   GotPltSection();
template <class ELFT> struct Out {
   static RelocationSection<ELFT> *RelaDyn;
   static RelocationSection<ELFT> *RelaPlt;
   static StringTableSection<ELFT> *DynStrTab;
   static StringTableSection<ELFT> *ShStrTab;
   static StringTableSection<ELFT> *StrTab;
   static SymbolTableSection<ELFT> *DynSymTab;
   static SymbolTableSection<ELFT> *SymTab;
   static Elf_Phdr *TlsPhdr;
-  static uint32_t LocalModuleTlsIndexOffset;
 };
 
 template <class ELFT> DynamicSection<ELFT> *Out<ELFT>::Dynamic;
 template <class ELFT> GnuHashTableSection<ELFT> *Out<ELFT>::GnuHashTab;
 template <class ELFT> GotPltSection<ELFT> *Out<ELFT>::GotPlt;
 template <class ELFT> GotSection<ELFT> *Out<ELFT>::Got;
 template <class ELFT> HashTableSection<ELFT> *Out<ELFT>::HashTab;
 template <class ELFT> InterpSection<ELFT> *Out<ELFT>::Interp;
 template <class ELFT> OutputSection<ELFT> *Out<ELFT>::Bss;
 template <class ELFT> OutputSection<ELFT> *Out<ELFT>::MipsRldMap;
 template <class ELFT> OutputSectionBase<ELFT> *Out<ELFT>::Opd;
 template <class ELFT> uint8_t *Out<ELFT>::OpdBuf;
 template <class ELFT> PltSection<ELFT> *Out<ELFT>::Plt;
 template <class ELFT> RelocationSection<ELFT> *Out<ELFT>::RelaDyn;
 template <class ELFT> RelocationSection<ELFT> *Out<ELFT>::RelaPlt;
 template <class ELFT> StringTableSection<ELFT> *Out<ELFT>::DynStrTab;
 template <class ELFT> StringTableSection<ELFT> *Out<ELFT>::ShStrTab;
 template <class ELFT> StringTableSection<ELFT> *Out<ELFT>::StrTab;
 template <class ELFT> SymbolTableSection<ELFT> *Out<ELFT>::DynSymTab;
 template <class ELFT> SymbolTableSection<ELFT> *Out<ELFT>::SymTab;
 template <class ELFT> typename Out<ELFT>::Elf_Phdr *Out<ELFT>::TlsPhdr;
-template <class ELFT> uint32_t Out<ELFT>::LocalModuleTlsIndexOffset = -1;
 
 } // namespace elf2
 } // namespace lld
 
 #endif // LLD_ELF_OUTPUT_SECTIONS_H

lld/trunk/ELF/OutputSections.cpp

 
 template <class ELFT> void GotSection<ELFT>::addDynTlsEntry(SymbolBody *Sym) {
   Sym->GotIndex = Target->getGotHeaderEntriesNum() + Entries.size();
   // Global Dynamic TLS entries take two GOT slots.
   Entries.push_back(Sym);
   Entries.push_back(nullptr);
 }
 
-template <class ELFT> uint32_t GotSection<ELFT>::addLocalModuleTlsIndex() {
+template <class ELFT> bool GotSection<ELFT>::addLocalModelTlsIndex() {
+  if (LocalTlsIndexOff != uint32_t(-1))
+    return false;
   Entries.push_back(nullptr);
   Entries.push_back(nullptr);
-  return (Entries.size() - 2) * sizeof(uintX_t);
+  LocalTlsIndexOff = (Entries.size() - 2) * sizeof(uintX_t);
+  return true;
 }
 
 template <class ELFT>
 typename GotSection<ELFT>::uintX_t
 GotSection<ELFT>::getEntryAddr(const SymbolBody &B) const {
   return this->getVA() + B.GotIndex * sizeof(uintX_t);
 }
 

 // Applies corresponding symbol and type for dynamic tls relocation.
 // Returns true if relocation was handled.
 template <class ELFT>
 bool RelocationSection<ELFT>::applyTlsDynamicReloc(SymbolBody *Body,
                                                    uint32_t Type, Elf_Rel *P,
                                                    Elf_Rel *N) {
   if (Target->isTlsLocalDynamicReloc(Type)) {
     P->setSymbolAndType(0, Target->getTlsModuleIndexReloc(), Config->Mips64EL);
-    P->r_offset =
-        Out<ELFT>::Got->getVA() + Out<ELFT>::LocalModuleTlsIndexOffset;
+    P->r_offset = Out<ELFT>::Got->getLocalTlsIndexVA();
     return true;
   }
 
   if (Body && Target->isTlsGlobalDynamicReloc(Type)) {
     P->setSymbolAndType(Body->getDynamicSymbolTableIndex(),
                         Target->getTlsModuleIndexReloc(), Config->Mips64EL);
     P->r_offset = Out<ELFT>::Got->getEntryAddr(*Body);
     N->setSymbolAndType(Body->getDynamicSymbolTableIndex(),

lld/trunk/ELF/Writer.cpp

void Writer<ELFT>::scanRelocs(
   for (const RelType &RI : Rels) {
     uint32_t SymIndex = RI.getSymbol(Config->Mips64EL);
     SymbolBody *Body = File.getSymbolBody(SymIndex);
     uint32_t Type = RI.getType(Config->Mips64EL);
 
     if (Target->isTlsLocalDynamicReloc(Type)) {
       if (Target->isTlsOptimized(Type, nullptr))
         continue;
-      if (Out<ELFT>::LocalModuleTlsIndexOffset == uint32_t(-1)) {
-        Out<ELFT>::LocalModuleTlsIndexOffset =
-            Out<ELFT>::Got->addLocalModuleTlsIndex();
+      if (Out<ELFT>::Got->addLocalModelTlsIndex())
         Out<ELFT>::RelaDyn->addReloc({&C, &RI});
-      }
       continue;
     }
 
     // Set "used" bit for --as-needed.
     if (Body && Body->isUndefined() && !Body->isWeak())
       if (auto *S = dyn_cast<SharedSymbol<ELFT>>(Body->repl()))
         S->File->IsUsed = true;