diff options
| -rw-r--r-- | lld/ELF/Relocations.cpp | 35 |
1 files changed, 22 insertions, 13 deletions
diff --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp index 43ede57f4ac..66e50361dab 100644 --- a/lld/ELF/Relocations.cpp +++ b/lld/ELF/Relocations.cpp @@ -553,17 +553,7 @@ static void errorOrWarn(const Twine &Msg) { template <class ELFT> static RelExpr adjustExpr(SymbolBody &Body, RelExpr Expr, RelType Type, - const uint8_t *Data, InputSectionBase &S, - typename ELFT::uint RelOff) { - if (Body.isGnuIFunc()) { - Expr = toPlt(Expr); - } else if (!isPreemptible(Body, Type)) { - if (needsPlt(Expr)) - Expr = fromPlt(Expr); - if (Expr == R_GOT_PC && !isAbsoluteValue(Body)) - Expr = Target->adjustRelaxExpr(Type, Data, Expr); - } - + InputSectionBase &S, uint64_t RelOff) { bool IsWrite = !Config->ZText || (S.Flags & SHF_WRITE); if (IsWrite || isStaticLinkTimeConstant<ELFT>(Expr, Type, Body, S, RelOff)) return Expr; @@ -869,8 +859,27 @@ static void scanRelocs(InputSectionBase &Sec, ArrayRef<RelTy> Rels) { continue; bool Preemptible = isPreemptible(Body, Type); - Expr = adjustExpr<ELFT>(Body, Expr, Type, Sec.Data.data() + Rel.r_offset, - Sec, Rel.r_offset); + + // Strenghten or relax a PLT access. + // + // GNU ifunc symbols must be accessed via PLT because their addresses + // are determined by runtime. + // + // On the other hand, if we know that a PLT entry will be resolved within + // the same ELF module, we can skip PLT access and directly jump to the + // destination function. For example, if we are linking a main exectuable, + // all dynamic symbols that can be resolved within the executable will + // actually be resolved that way at runtime, because the main exectuable + // is always at the beginning of a search list. We can leverage that fact. + if (Body.isGnuIFunc()) + Expr = toPlt(Expr); + else if (!Preemptible && Expr == R_GOT_PC && !isAbsoluteValue(Body)) + Expr = + Target->adjustRelaxExpr(Type, Sec.Data.data() + Rel.r_offset, Expr); + else if (!Preemptible) + Expr = fromPlt(Expr); + + Expr = adjustExpr<ELFT>(Body, Expr, Type, Sec, Rel.r_offset); if (ErrorCount) continue; |
