[lld] r309652 - Binary search to find a relocation.

[Rui Ueyama via llvm-commits]

Yes, looks like lld's -gdb-index is now much faster than gold's.

On Wed, Aug 2, 2017 at 2:02 AM, Rafael Avila de Espindola <
rafael.espindola at gmail.com> wrote:

> This is awesome. It takes a link of clang with gdb index from about 21
> seconds to 13.5 seconds for me!
>
> Cheers,
> Rafael
>
> Rui Ueyama via llvm-commits <llvm-commits at lists.llvm.org> writes:
>
> > Author: ruiu
> > Date: Mon Jul 31 21:11:03 2017
> > New Revision: 309652
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=309652&view=rev
> > Log:
> > Binary search to find a relocation.
> >
> > This change makes -gdb-index 40% faster. My test case is self-linking
> lld.
> >
> > Differential Revision: https://reviews.llvm.org/D36079
> >
> > Modified:
> >     lld/trunk/ELF/GdbIndex.cpp
> >
> > Modified: lld/trunk/ELF/GdbIndex.cpp
> > URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/
> GdbIndex.cpp?rev=309652&r1=309651&r2=309652&view=diff
> > ============================================================
> ==================
> > --- lld/trunk/ELF/GdbIndex.cpp (original)
> > +++ lld/trunk/ELF/GdbIndex.cpp Mon Jul 31 21:11:03 2017
> > @@ -79,11 +79,13 @@ template <class RelTy>
> >  Optional<RelocAddrEntry>
> >  LLDDwarfObj<ELFT>::findAux(const InputSectionBase &Sec, uint64_t Pos,
> >                             ArrayRef<RelTy> Rels) const {
> > -  auto I = llvm::find_if(Rels,
> > -                         [=](const RelTy &Rel) { return Rel.r_offset ==
> Pos; });
> > -  if (I == Rels.end())
> > +  auto It = std::lower_bound(
> > +      Rels.begin(), Rels.end(), Pos,
> > +      [](const RelTy &A, uint64_t B) { return A.r_offset < B; });
> > +  if (It == Rels.end() || It->r_offset != Pos)
> >      return None;
> > -  const RelTy &Rel = *I;
> > +  const RelTy &Rel = *It;
> > +
> >    const ObjFile<ELFT> *File = Sec.getFile<ELFT>();
> >    uint32_t SymIndex = Rel.getSymbol(Config->IsMips64EL);
> >    const typename ELFT::Sym &Sym = File->getELFSymbols()[SymIndex];
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
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