[lld] r270573 - Fix a wrong assumption.

[Rui Ueyama via llvm-commits]

On Tue, May 24, 2016 at 9:03 AM, Rafael Espindola via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: rafael
> Date: Tue May 24 11:03:27 2016
> New Revision: 270573
>
> URL: http://llvm.org/viewvc/llvm-project?rev=270573&view=rev
> Log:
> Fix a wrong assumption.
>
> Added:
>     lld/trunk/test/ELF/eh-frame-multilpe-cie.s
> 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=270573&r1=270572&r2=270573&view=diff
>
> ==============================================================================
> --- lld/trunk/ELF/OutputSections.cpp (original)
> +++ lld/trunk/ELF/OutputSections.cpp Tue May 24 11:03:27 2016
> @@ -964,14 +964,6 @@ CieRecord *EhOutputSection<ELFT>::addCie
>    return Cie;
>  }
>
> -template <class ELFT> static void validateFde(SectionPiece &Piece) {
> -  // We assume that all FDEs refer the first CIE in the same object file.
> -  const endianness E = ELFT::TargetEndianness;
> -  uint32_t ID = read32<E>(Piece.Data.data() + 4);
> -  if (Piece.InputOff + 4 - ID != 0)
> -    fatal("invalid CIE reference");
> -}
> -
>  // There is one FDE per function. Returns true if a given FDE
>  // points to a live function.
>  template <class ELFT>
> @@ -998,19 +990,30 @@ template <class ELFT>
>  template <class RelTy>
>  void EhOutputSection<ELFT>::addSectionAux(EhInputSection<ELFT> *Sec,
>                                            ArrayRef<RelTy> Rels) {
> -  SectionPiece &CiePiece = Sec->Pieces[0];
> -  // The empty record is the end marker.
> -  if (CiePiece.Data.size() == 4)
> -    return;
> -
> -  CieRecord *Cie = addCie(CiePiece, Sec, Rels);
> -
> -  for (size_t I = 1, End = Sec->Pieces.size(); I != End; ++I) {
> -    SectionPiece &FdePiece = Sec->Pieces[I];
> -    validateFde<ELFT>(FdePiece);
> -    if (!isFdeLive(FdePiece, Sec, Rels))
> +  const endianness E = ELFT::TargetEndianness;
> +
> +  DenseMap<size_t, CieRecord *> OffsetToCie;
> +  for (size_t I = 0, End = Sec->Pieces.size(); I != End; ++I) {
> +    SectionPiece &Piece = Sec->Pieces[I];
> +    // The empty record is the end marker.
> +    if (Piece.Data.size() == 4)
> +      continue;
>

It looks odd to continue after the end marker. Do you want to return here
instead?


> +
> +    size_t Offset = Piece.InputOff;
> +    uint32_t ID = read32<E>(Piece.Data.data() + 4);
> +    if (ID == 0) {
> +      OffsetToCie[Offset] = addCie(Piece, Sec, Rels);
> +      continue;
> +    }
> +
> +    uint32_t CieOffset = Offset + 4 - ID;
> +    CieRecord *Cie = OffsetToCie[CieOffset];
> +    if (!Cie)
> +      fatal("invalid CIE reference");
> +
> +    if (!isFdeLive(Piece, Sec, Rels))
>        continue;
> -    Cie->FdePieces.push_back(&FdePiece);
> +    Cie->FdePieces.push_back(&Piece);
>      NumFdes++;
>    }
>  }
>
> Added: lld/trunk/test/ELF/eh-frame-multilpe-cie.s
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/eh-frame-multilpe-cie.s?rev=270573&view=auto
>
> ==============================================================================
> --- lld/trunk/test/ELF/eh-frame-multilpe-cie.s (added)
> +++ lld/trunk/test/ELF/eh-frame-multilpe-cie.s Tue May 24 11:03:27 2016
> @@ -0,0 +1,12 @@
> +// RUN: llvm-mc %s -o %t.o -filetype=obj -triple=x86_64-pc-linux
> +// RUN: ld.lld --eh-frame-hdr %t.o -o %t.so -shared
> +// We would fail to parse multiple cies in the same file.
> +
> +        .cfi_startproc
> +        .cfi_personality 0x9b, foo
> +        .cfi_endproc
> +
> +        .cfi_startproc
> +        .cfi_endproc
> +
> +foo:
>
>
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