[ELF] - Remove dead TLS relocations relative code for MIPS and ARM

[grimar]

Summary

Found that this code not used because of
handleARMTlsRelocation and handleMipsTlsRelocation methods that are called
for these platforms instead of regular TLS code.

So, it is dead code that we can remove I think, or do we need it for some reason ?

[peter.smith]

I don't have any objections to it being removed. It can be reintroduced if we need it later.

Perhaps the names of those functions are a bit general, for example should isTlsLocalDynamicRel() be isRelaxableTlsDynamicRel()?

[atanasyan]

I have no objections to removing these methods.

[grimar]

In D32355#733674, @peter.smith wrote:

Perhaps the names of those functions are a bit general, for example should isTlsLocalDynamicRel() be isRelaxableTlsDynamicRel()?

I would keep the names. It seems that isRelaxableTlsDynamicRel is too generic probably.
TLS optimization spec defines explicitly the transitions between different models,
for example general dynamic model can be relaxed to initial exes or local exec, local dynamic to local exec, initial exec to local exec.
And our current code currently proccesses these models in a pretty obvious way using the current names.

Rui, are you ok with landing cleanup introduced in this patch ?

[ruiu]

LGTM

lld/trunk/ELF/Target.cpp

 class ARMTargetInfo final : public TargetInfo {
 public:
   ARMTargetInfo();
   RelExpr getRelExpr(uint32_t Type, const SymbolBody &S,
                      const uint8_t *Loc) const override;
   bool isPicRel(uint32_t Type) const override;
   uint32_t getDynRel(uint32_t Type) const override;
   int64_t getImplicitAddend(const uint8_t *Buf, uint32_t Type) const override;
-  bool isTlsLocalDynamicRel(uint32_t Type) const override;
-  bool isTlsInitialExecRel(uint32_t Type) const override;
   void writeGotPlt(uint8_t *Buf, const SymbolBody &S) const override;
   void writeIgotPlt(uint8_t *Buf, const SymbolBody &S) const override;
   void writePltHeader(uint8_t *Buf) const override;
   void writePlt(uint8_t *Buf, uint64_t GotPltEntryAddr, uint64_t PltEntryAddr,
                 int32_t Index, unsigned RelOff) const override;
   void addPltSymbols(InputSectionBase *IS, uint64_t Off) const override;
   void addPltHeaderSymbols(InputSectionBase *ISD) const override;
   bool needsThunk(RelExpr Expr, uint32_t RelocType, const InputFile *File,
                   const SymbolBody &S) const override;
   void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
 };
 
 template <class ELFT> class MipsTargetInfo final : public TargetInfo {
 public:
   MipsTargetInfo();
   RelExpr getRelExpr(uint32_t Type, const SymbolBody &S,
                      const uint8_t *Loc) const override;
   int64_t getImplicitAddend(const uint8_t *Buf, uint32_t Type) const override;
   bool isPicRel(uint32_t Type) const override;
   uint32_t getDynRel(uint32_t Type) const override;
-  bool isTlsLocalDynamicRel(uint32_t Type) const override;
   void writeGotPlt(uint8_t *Buf, const SymbolBody &S) const override;
   void writePltHeader(uint8_t *Buf) const override;
   void writePlt(uint8_t *Buf, uint64_t GotPltEntryAddr, uint64_t PltEntryAddr,
                 int32_t Index, unsigned RelOff) const override;
   bool needsThunk(RelExpr Expr, uint32_t RelocType, const InputFile *File,
                   const SymbolBody &S) const override;
   void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
   bool usesOnlyLowPageBits(uint32_t Type) const override;
case R_ARM_THM_MOVT_PREL: {
     return SignExtend64<16>(((Hi & 0x000f) << 12) | // imm4
                             ((Hi & 0x0400) << 1) |  // i
                             ((Lo & 0x7000) >> 4) |  // imm3
                             (Lo & 0x00ff));         // imm8
   }
   }
 }
 
-bool ARMTargetInfo::isTlsLocalDynamicRel(uint32_t Type) const {
-  return Type == R_ARM_TLS_LDO32 || Type == R_ARM_TLS_LDM32;
-}
-
-bool ARMTargetInfo::isTlsInitialExecRel(uint32_t Type) const {
-  return Type == R_ARM_TLS_IE32;
-}
-
 template <class ELFT> MipsTargetInfo<ELFT>::MipsTargetInfo() {
   GotPltHeaderEntriesNum = 2;
   DefaultMaxPageSize = 65536;
   GotEntrySize = sizeof(typename ELFT::uint);
   GotPltEntrySize = sizeof(typename ELFT::uint);
   PltEntrySize = 16;
   PltHeaderSize = 32;
   CopyRel = R_MIPS_COPY;

 }
 
 template <class ELFT>
 uint32_t MipsTargetInfo<ELFT>::getDynRel(uint32_t Type) const {
   return RelativeRel;
 }
 
 template <class ELFT>
-bool MipsTargetInfo<ELFT>::isTlsLocalDynamicRel(uint32_t Type) const {
-  return Type == R_MIPS_TLS_LDM;
-}
-
-template <class ELFT>
 void MipsTargetInfo<ELFT>::writeGotPlt(uint8_t *Buf, const SymbolBody &) const {
   write32<ELFT::TargetEndianness>(Buf, In<ELFT>::Plt->getVA());
 }
 
 template <endianness E, uint8_t BSIZE, uint8_t SHIFT>
 static int64_t getPcRelocAddend(const uint8_t *Loc) {
   uint32_t Instr = read32<E>(Loc);
   uint32_t Mask = 0xffffffff >> (32 - BSIZE);