[lld] r270325 - Split EHOutputSection<ELFT>::addSectionAux. NFC.

[Rui Ueyama via llvm-commits]

Addressed in r270572. But your comment made me wonder if we should do
binary search rather than sequential search at the last position.

On Tue, May 24, 2016 at 6:24 AM, Rafael Espíndola <
rafael.espindola at gmail.com> wrote:

> With this change we now scan every relocation for each cie. Before we
> use to use the fact that the relocations are sorted and not start from
> scratch. I measured a 2% performance regression when linking chromium
> with this.
>
> Cheers,
> Rafael
>
>
> On 21 May 2016 at 15:06, Rui Ueyama via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
> > Author: ruiu
> > Date: Sat May 21 14:06:33 2016
> > New Revision: 270325
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=270325&view=rev
> > Log:
> > Split EHOutputSection<ELFT>::addSectionAux. NFC.
> >
> > Modified:
> >     lld/trunk/ELF/OutputSections.cpp
> >
> > Modified: lld/trunk/ELF/OutputSections.cpp
> > URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.cpp?rev=270325&r1=270324&r2=270325&view=diff
> >
> ==============================================================================
> > --- lld/trunk/ELF/OutputSections.cpp (original)
> > +++ lld/trunk/ELF/OutputSections.cpp Sat May 21 14:06:33 2016
> > @@ -1114,6 +1114,19 @@ static typename ELFT::uint readEntryLeng
> >    return Len;
> >  }
> >
> > +// Returns the first relocation that points to a region
> > +// between Begin and Begin+Size.
> > +template <class IntTy, class RelTy>
> > +static const RelTy *getReloc(IntTy Begin, IntTy Size, ArrayRef<RelTy>
> Rels) {
> > +  size_t I = 0;
> > +  size_t E = Rels.size();
> > +  while (I != E && Rels[I].r_offset < Begin)
> > +    ++I;
> > +  if (I == E || Begin + Size <= Rels[I].r_offset)
> > +    return nullptr;
> > +  return &Rels[I];
> > +}
> > +
> >  template <class ELFT>
> >  template <class RelTy>
> >  void EHOutputSection<ELFT>::addSectionAux(EHInputSection<ELFT> *S,
> > @@ -1127,8 +1140,6 @@ void EHOutputSection<ELFT>::addSectionAu
> >    ArrayRef<uint8_t> SecData = S->getSectionData();
> >    ArrayRef<uint8_t> D = SecData;
> >    uintX_t Offset = 0;
> > -  auto RelI = Rels.begin();
> > -  auto RelE = Rels.end();
> >
> >    DenseMap<unsigned, unsigned> OffsetToIndex;
> >    while (!D.empty()) {
> > @@ -1142,11 +1153,6 @@ void EHOutputSection<ELFT>::addSectionAu
> >        break;
> >      StringRef Entry((const char *)D.data(), Length);
> >
> > -    while (RelI != RelE && RelI->r_offset < Offset)
> > -      ++RelI;
> > -    uintX_t NextOffset = Offset + Length;
> > -    bool HasReloc = RelI != RelE && RelI->r_offset < NextOffset;
> > -
> >      uint32_t ID = read32<E>(D.data() + 4);
> >      if (ID == 0) {
> >        // CIE
> > @@ -1155,8 +1161,8 @@ void EHOutputSection<ELFT>::addSectionAu
> >          C.FdeEncoding = getFdeEncoding(D);
> >
> >        SymbolBody *Personality = nullptr;
> > -      if (HasReloc)
> > -        Personality = &S->getFile()->getRelocTargetSym(*RelI);
> > +      if (const RelTy *Rel = getReloc(Offset, Length, Rels))
> > +        Personality = &S->getFile()->getRelocTargetSym(*Rel);
> >
> >        std::pair<StringRef, SymbolBody *> CieInfo(Entry, Personality);
> >        auto P = CieMap.insert(std::make_pair(CieInfo, Cies.size()));
> > @@ -1166,9 +1172,11 @@ void EHOutputSection<ELFT>::addSectionAu
> >        }
> >        OffsetToIndex[Offset] = P.first->second;
> >      } else {
> > -      if (!HasReloc)
> > +      const RelTy *Rel = getReloc(Offset, Length, Rels);
> > +      if (!Rel)
> >          fatal("FDE doesn't reference another section");
> > -      SymbolBody &B = S->getFile()->getRelocTargetSym(*RelI);
> > +      SymbolBody &B = S->getFile()->getRelocTargetSym(*Rel);
> > +
> >        auto *D = dyn_cast<DefinedRegular<ELFT>>(&B);
> >        if (D && D->Section) {
> >          InputSectionBase<ELFT> *Target = D->Section->Repl;
> > @@ -1184,7 +1192,7 @@ void EHOutputSection<ELFT>::addSectionAu
> >        }
> >      }
> >
> > -    Offset = NextOffset;
> > +    Offset += Length;
> >      D = D.slice(Length);
> >    }
> >  }
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
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