[ELF2] Implement PPC64TargetInfo::isRelRelative

[hfinkel]

Summary

This is essentially patern-matching against the x86 target. It is still missing a test case, but feedback is certainly appreciated.

[ruiu]

This change seems good, but we need a test for this indeed.

[davide]

Hal, I think the change is correct. Please add a test preferably written in assembler.
The only comment if have is -- can you please add \n immediately right before and after the function?

[hfinkel]

Added a test case (and some new lines).

[ruiu]

LGTM

[hfinkel]

r250102, thanks!

ELF/Target.h

public:
   PPC64TargetInfo();
   void writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
                      uint64_t PltEntryAddr) const override;
   bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
   bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
   void relocateOne(uint8_t *Buf, const void *RelP, uint32_t Type,
                    uint64_t BaseAddr, uint64_t SymVA,
                    uint64_t GotVA) const override;
+  bool isRelRelative(uint32_t Type) const override;
 };
 
 class PPCTargetInfo final : public TargetInfo {
 public:
   PPCTargetInfo();
   void writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
                      uint64_t PltEntryAddr) const override;
   bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;

ELF/Target.cpp

 static inline uint16_t applyPPChighesta (uint64_t value) {
   return ((value + 0x8000) >> 48) & 0xffff;
 }
 
 PPC64TargetInfo::PPC64TargetInfo() {
   PCRelReloc = R_PPC64_REL24;
   GotReloc = R_PPC64_GLOB_DAT;
   GotRefReloc = R_PPC64_REL64;
+  RelativeReloc = R_PPC64_RELATIVE;
   PltEntrySize = 32;
   PageSize = 0x10000;
   VAStart = 0x10000000;
 }
 void PPC64TargetInfo::writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
                                     uint64_t PltEntryAddr) const {
   std::fill(Buf, Buf + getPltEntrySize(), 0);
 

 bool PPC64TargetInfo::relocNeedsPlt(uint32_t Type, const SymbolBody &S) const {
   switch (Type) {
   default: return false;
   case R_PPC64_REL24:
     // These are function calls that need to be redirected through a PLT stub.
     return S.isShared() || (S.isUndefined() && S.isWeak());
   }
 }
+bool PPC64TargetInfo::isRelRelative(uint32_t Type) const {
+  switch (Type) {
+  default:
+    return false;
+  case R_PPC64_REL24:
+  case R_PPC64_REL14:
+  case R_PPC64_REL14_BRTAKEN:
+  case R_PPC64_REL14_BRNTAKEN:
+  case R_PPC64_REL32:
+    return true;
+  }
+}
 void PPC64TargetInfo::relocateOne(uint8_t *Buf, const void *RelP, uint32_t Type,
                                   uint64_t BaseAddr, uint64_t SymVA,
                                   uint64_t GotVA) const {
   typedef ELFFile<ELF64BE>::Elf_Rela Elf_Rela;
   auto &Rel = *reinterpret_cast<const Elf_Rela *>(RelP);
   int64_t Addend = Rel.r_addend;
 
   // The TOC consists of sections .got, .toc, .tocbss, .plt in that