Simplify Symbol::getPltVA.

[ruiu]

Summary

This patch also makes getPltEntryOffset a non-member function because
it doesn't depend on any private members of the TargetInfo class.

I tried a few different ideas, and it seems this change fits in best
to me.

ELF/Arch/X86_64.cpp

const uint8_t Insn[] = {
       0xe8, 0,    0,    0,    0,    // 7:  callq plt+0x20
       0xe9, 0,    0,    0,    0,    // c:  jmp plt+0x12
       0x68, 0,    0,    0,    0,    // 11: pushq <relocation index>
       0xe9, 0,    0,    0,    0,    // 16: jmp plt+0
       0xcc, 0xcc, 0xcc, 0xcc, 0xcc, // 1b: int3; padding
   };
   memcpy(Buf, Insn, sizeof(Insn));
 
-  uint64_t Off = TargetInfo::getPltEntryOffset(Index);
+  uint64_t Off = getPltEntryOffset(Index);
 
   write32le(Buf + 3, GotPltEntryAddr - PltEntryAddr - 7);
   write32le(Buf + 8, -Off - 12 + 32);
   write32le(Buf + 13, -Off - 17 + 18);
   write32le(Buf + 18, Index);
   write32le(Buf + 23, -Off - 27);
 }
 
void RetpolineZNow<ELFT>::writePlt(uint8_t *Buf, uint64_t GotPltEntryAddr,
   const uint8_t Insn[] = {
       0x4c, 0x8b, 0x1d, 0,    0, 0, 0, // mov foo@GOTPLT(%rip), %r11
       0xe9, 0,    0,    0,    0,       // jmp plt+0
       0xcc, 0xcc, 0xcc, 0xcc,          // int3; padding
   };
   memcpy(Buf, Insn, sizeof(Insn));
 
   write32le(Buf + 3, GotPltEntryAddr - PltEntryAddr - 7);
-  write32le(Buf + 8, -TargetInfo::getPltEntryOffset(Index) - 12);
+  write32le(Buf + 8, -getPltEntryOffset(Index) - 12);
 }
 
 template <class ELFT> static TargetInfo *getTargetInfo() {
   if (Config->ZRetpolineplt) {
     if (Config->ZNow) {
       static RetpolineZNow<ELFT> T;
       return &T;
     }

ELF/Relocations.cpp

if (Sym.isFunc()) {
     //   the wrong ebx value.
     if (Config->Pie && Config->EMachine == EM_386)
       errorOrWarn("symbol '" + toString(Sym) +
                   "' cannot be preempted; recompile with -fPIE" +
                   getLocation(Sec, Sym, Offset));
     if (!Sym.isInPlt())
       addPltEntry<ELFT>(In.Plt, In.GotPlt, In.RelaPlt, Target->PltRel, Sym);
     if (!Sym.isDefined())
-      replaceWithDefined(Sym, In.Plt, Sym.getPltOffset(), 0);
+      replaceWithDefined(Sym, In.Plt, getPltEntryOffset(Sym.PltIndex), 0);
     Sym.NeedsPltAddr = true;
     Sec.Relocations.push_back({Expr, Type, Offset, Addend, &Sym});
     return;
   }
 
   errorOrWarn("symbol '" + toString(Sym) + "' has no type" +
               getLocation(Sec, Sym, Offset));
 }

ELF/Symbols.h

public:
 
   uint64_t getVA(int64_t Addend = 0) const;
 
   uint64_t getGotOffset() const;
   uint64_t getGotVA() const;
   uint64_t getGotPltOffset() const;
   uint64_t getGotPltVA() const;
   uint64_t getPltVA() const;
-  uint64_t getPltOffset() const;
   uint64_t getPPC64LongBranchTableVA() const;
   uint64_t getPPC64LongBranchOffset() const;
   uint64_t getSize() const;
   OutputSection *getOutputSection() const;
 
 protected:
   Symbol(Kind K, InputFile *File, StringRefZ Name, uint8_t Binding,
          uint8_t StOther, uint8_t Type)

ELF/Symbols.cpp

 }
 
 uint64_t Symbol::getPPC64LongBranchOffset() const {
   assert(PPC64BranchltIndex != 0xffff);
   return PPC64BranchltIndex * Target->GotPltEntrySize;
 }
 
 uint64_t Symbol::getPltVA() const {
-  if (this->IsInIplt) {
-    if (Config->ZRetpolineplt)
-      return In.Iplt->getVA() + Target->getPltEntryOffset(PltIndex);
-    return In.Iplt->getVA() + PltIndex * Target->PltEntrySize;
-  }
-  return In.Plt->getVA() + Target->getPltEntryOffset(PltIndex);
-}
-
-uint64_t Symbol::getPltOffset() const {
-  assert(!this->IsInIplt);
-  return Target->getPltEntryOffset(PltIndex);
+  PltSection *Plt = IsInIplt ? In.Iplt : In.Plt;
+  return Plt->getVA() + Plt->HeaderSize + PltIndex * Target->PltEntrySize;
 }
 
 uint64_t Symbol::getPPC64LongBranchTableVA() const {
   assert(PPC64BranchltIndex != 0xffff);
   return In.PPC64LongBranchTarget->getVA() +
          PPC64BranchltIndex * Target->GotPltEntrySize;
 }
 

ELF/SyntheticSections.h

 // Target->IRelativeRel.
 class PltSection : public SyntheticSection {
 public:
   PltSection(bool IsIplt);
   void writeTo(uint8_t *Buf) override;
   size_t getSize() const override;
   bool empty() const override { return Entries.empty(); }
   void addSymbols();
-
   template <class ELFT> void addEntry(Symbol &Sym);
 
+  size_t HeaderSize;
+
 private:
   unsigned getPltRelocOff() const;
   std::vector<std::pair<const Symbol *, unsigned>> Entries;
-  size_t HeaderSize;
   bool IsIplt;
 };
 
 class GdbIndexSection final : public SyntheticSection {
 public:
   struct AddressEntry {
     InputSection *Section;
     uint64_t LowAddress;

ELF/Target.h

public:
   virtual void writePltHeader(uint8_t *Buf) const {}
 
   virtual void writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
                         uint64_t PltEntryAddr, int32_t Index,
                         unsigned RelOff) const {}
   virtual void addPltHeaderSymbols(InputSection &IS) const {}
   virtual void addPltSymbols(InputSection &IS, uint64_t Off) const {}
 
-  unsigned getPltEntryOffset(unsigned Index) const {
-    return Index * PltEntrySize + PltHeaderSize;
-  }
-
   // Returns true if a relocation only uses the low bits of a value such that
   // all those bits are in the same page. For example, if the relocation
   // only uses the low 12 bits in a system with 4k pages. If this is true, the
   // bits will always have the same value at runtime and we don't have to emit
   // a dynamic relocation.
   virtual bool usesOnlyLowPageBits(RelType Type) const;
 
   // Decide whether a Thunk is needed for the relocation from File
if (ErrPlace.IS && ErrPlace.IS->Name.startswith(".debug"))
     Hint = "; consider recompiling with -fdebug-types-section to reduce size "
            "of debug sections";
 
   errorOrWarn(ErrPlace.Loc + "relocation " + lld::toString(Type) +
               " out of range: " + V.str() + " is not in [" + Twine(Min).str() +
               ", " + Twine(Max).str() + "]" + Hint);
 }
 
+inline unsigned getPltEntryOffset(unsigned Idx) {
+  return Target->PltHeaderSize + Target->PltEntrySize * Idx;
+}
+
 // Make sure that V can be represented as an N bit signed integer.
 inline void checkInt(uint8_t *Loc, int64_t V, int N, RelType Type) {
   if (V != llvm::SignExtend64(V, N))
     reportRangeError(Loc, Type, Twine(V), llvm::minIntN(N), llvm::maxIntN(N));
 }
 
 // Make sure that V can be represented as an N bit unsigned integer.
 inline void checkUInt(uint8_t *Loc, uint64_t V, int N, RelType Type) {