[lld] Rename R_TLSGD/R_TLSLD to R_TLSGD_FROM_END/R_TLSLD_FROM_END [NFC]

[sfertile]

Summary

getRelocTargetVA for R_TLSGD and R_TLSLD RelExprs calculate an offset from the end of the got, so adjust the names to reflect this.

[ruiu]

LGTM

[grimar]

New naming is confusing IMO. We had R_GOTONLY_PC_FROM_END, R_GOT_FROM_END and R_GOTREL_FROM_END.
Since names contains "GOT" it is clear that "FROM_END" says about the end of GOT.

But R_TLSGD_FROM_END is different made me think about the end of TLS first of all.

[sfertile]

In D47379#1113896, @grimar wrote:

New naming is confusing IMO. We had R_GOTONLY_PC_FROM_END, R_GOT_FROM_END and R_GOTREL_FROM_END.
Since names contains "GOT" it is clear that "FROM_END" says about the end of GOT.

But R_TLSGD_FROM_END is different made me think about the end of TLS first of all.

Fair enough, would anybody object to R_TLSGD_GOT_FROM_END and R_TLSLD_GOT_FROM_END?

[grimar]

In D47379#1114087, @sfertile wrote:

In D47379#1113896, @grimar wrote:

New naming is confusing IMO. We had R_GOTONLY_PC_FROM_END, R_GOT_FROM_END and R_GOTREL_FROM_END.
Since names contains "GOT" it is clear that "FROM_END" says about the end of GOT.

But R_TLSGD_FROM_END is different made me think about the end of TLS first of all.

Fair enough, would anybody object to R_TLSGD_GOT_FROM_END and R_TLSLD_GOT_FROM_END?

Sounds good to me. Let's see what Rui think.

[ruiu]

Sounds good to me.

ELF/Arch/X86.cpp

RelExpr X86::getRelExpr(RelType Type, const Symbol &S,
                         const uint8_t *Loc) const {
   switch (Type) {
   case R_386_8:
   case R_386_16:
   case R_386_32:
   case R_386_TLS_LDO_32:
     return R_ABS;
   case R_386_TLS_GD:
-    return R_TLSGD;
+    return R_TLSGD_FROM_END;
   case R_386_TLS_LDM:
-    return R_TLSLD;
+    return R_TLSLD_FROM_END;
   case R_386_PLT32:
     return R_PLT_PC;
   case R_386_PC8:
   case R_386_PC16:
   case R_386_PC32:
     return R_PC;
   case R_386_GOTPC:
     return R_GOTONLY_PC_FROM_END;

ELF/InputSection.cpp

case R_NEG_TLS:
     return Out::TlsPhdr->p_memsz - Sym.getVA(A);
   case R_SIZE:
     return Sym.getSize() + A;
   case R_TLSDESC:
     return InX::Got->getGlobalDynAddr(Sym) + A;
   case R_TLSDESC_PAGE:
     return getAArch64Page(InX::Got->getGlobalDynAddr(Sym) + A) -
            getAArch64Page(P);
-  case R_TLSGD:
+  case R_TLSGD_FROM_END:
     return InX::Got->getGlobalDynOffset(Sym) + A - InX::Got->getSize();
   case R_TLSGD_PC:
     return InX::Got->getGlobalDynAddr(Sym) + A - P;
-  case R_TLSLD:
+  case R_TLSLD_FROM_END:
     return InX::Got->getTlsIndexOff() + A - InX::Got->getSize();
   case R_TLSLD_PC:
     return InX::Got->getTlsIndexVA() + A - P;
   }
   llvm_unreachable("Invalid expression");
 }
 
 // This function applies relocations to sections without SHF_ALLOC bit.

ELF/Relocations.h

enum RelExpr {
   R_RELAX_TLS_GD_TO_LE_NEG,
   R_RELAX_TLS_IE_TO_LE,
   R_RELAX_TLS_LD_TO_LE,
   R_SIZE,
   R_TLS,
   R_TLSDESC,
   R_TLSDESC_CALL,
   R_TLSDESC_PAGE,
-  R_TLSGD,
+  R_TLSGD_FROM_END,
   R_TLSGD_PC,
-  R_TLSLD,
+  R_TLSLD_FROM_END,
   R_TLSLD_PC,
 };
 
 // Build a bitmask with one bit set for each RelExpr.
 //
 // Constexpr function arguments can't be used in static asserts, so we
 // use template arguments to build the mask.
 // But function template partial specializations don't exist (needed

ELF/Relocations.cpp

if (InX::Got->addDynTlsEntry(Sym)) {
       InX::RelaDyn->addReloc(
           {Target->TlsDescRel, InX::Got, Off, !Sym.IsPreemptible, &Sym, 0});
     }
     if (Expr != R_TLSDESC_CALL)
       C.Relocations.push_back({Expr, Type, Offset, Addend, &Sym});
     return 1;
   }
 
-  if (isRelExprOneOf<R_TLSLD_PC, R_TLSLD>(Expr)) {
+  if (isRelExprOneOf<R_TLSLD_PC, R_TLSLD_FROM_END>(Expr)) {
     // Local-Dynamic relocs can be relaxed to Local-Exec.
     if (!Config->Shared) {
       C.Relocations.push_back(
           {R_RELAX_TLS_LD_TO_LE, Type, Offset, Addend, &Sym});
       return 2;
     }
     if (InX::Got->addTlsIndex())
       InX::RelaDyn->addReloc(Target->TlsModuleIndexRel, InX::Got,
                              InX::Got->getTlsIndexOff(), nullptr);
     C.Relocations.push_back({Expr, Type, Offset, Addend, &Sym});
     return 1;
   }
 
   // Local-Dynamic relocs can be relaxed to Local-Exec.
-  if (isRelExprOneOf<R_ABS, R_TLSLD, R_TLSLD_PC>(Expr) && !Config->Shared) {
+  if (isRelExprOneOf<R_ABS, R_TLSLD_FROM_END, R_TLSLD_PC>(Expr) &&
+      !Config->Shared) {
     C.Relocations.push_back({R_RELAX_TLS_LD_TO_LE, Type, Offset, Addend, &Sym});
     return 1;
   }
 
-  if (isRelExprOneOf<R_TLSDESC, R_TLSDESC_PAGE, R_TLSDESC_CALL, R_TLSGD,
-                     R_TLSGD_PC>(Expr)) {
+  if (isRelExprOneOf<R_TLSDESC, R_TLSDESC_PAGE, R_TLSDESC_CALL,
+                     R_TLSGD_FROM_END, R_TLSGD_PC>(Expr)) {
     if (Config->Shared) {
       if (InX::Got->addDynTlsEntry(Sym)) {
         uint64_t Off = InX::Got->getGlobalDynOffset(Sym);
         InX::RelaDyn->addReloc(Target->TlsModuleIndexRel, InX::Got, Off, &Sym);
 
         // If the symbol is preemptible we need the dynamic linker to write
         // the offset too.
         uint64_t OffsetOff = Off + Config->Wordsize;

 // dynamic relocation so that the relocation will be fixed at load-time.
 static bool isStaticLinkTimeConstant(RelExpr E, RelType Type, const Symbol &Sym,
                                      InputSectionBase &S, uint64_t RelOff) {
   // These expressions always compute a constant
   if (isRelExprOneOf<R_GOT_FROM_END, R_GOT_OFF, R_MIPS_GOT_LOCAL_PAGE,
                      R_MIPS_GOTREL, R_MIPS_GOT_OFF, R_MIPS_GOT_OFF32,
                      R_MIPS_GOT_GP_PC, R_MIPS_TLSGD, R_GOT_PAGE_PC, R_GOT_PC,
                      R_GOTONLY_PC, R_GOTONLY_PC_FROM_END, R_PLT_PC, R_TLSGD_PC,
-                     R_TLSGD, R_PPC_CALL_PLT, R_TLSDESC_CALL, R_TLSDESC_PAGE,
-                     R_HINT>(E))
+                     R_TLSGD_FROM_END, R_PPC_CALL_PLT, R_TLSDESC_CALL,
+                     R_TLSDESC_PAGE, R_HINT>(E))
     return true;
 
   // These never do, except if the entire file is position dependent or if
   // only the low bits are used.
   if (E == R_GOT || E == R_PLT || E == R_TLSDESC)
     return Target->usesOnlyLowPageBits(Type) || !Config->Pic;
 
   if (Sym.IsPreemptible)