[lld] r248382 - Print more information about undefined symbols.

[Sean Silva via llvm-commits]

On Wed, Sep 23, 2015 at 7:37 AM, Rafael Espindola via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: rafael
> Date: Wed Sep 23 09:37:01 2015
> New Revision: 248382
>
> URL: http://llvm.org/viewvc/llvm-project?rev=248382&view=rev
> Log:
> Print more information about undefined symbols.
>
> Modified:
>     lld/trunk/ELF/Writer.cpp
>     lld/trunk/test/elf2/undef.s
>
> Modified: lld/trunk/ELF/Writer.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=248382&r1=248381&r2=248382&view=diff
>
> ==============================================================================
> --- lld/trunk/ELF/Writer.cpp (original)
> +++ lld/trunk/ELF/Writer.cpp Wed Sep 23 09:37:01 2015
> @@ -288,6 +288,27 @@ void Writer<ELFT>::scanRelocs(const Inpu
>    }
>  }
>
> +template <class ELFT>
> +static void undefError(const SymbolTable &S, const SymbolBody &Sym) {
> +  typedef typename ELFFile<ELFT>::Elf_Sym Elf_Sym;
> +  typedef typename ELFFile<ELFT>::Elf_Sym_Range Elf_Sym_Range;
> +
> +  const Elf_Sym &SymE = cast<ELFSymbolBody<ELFT>>(Sym).Sym;
> +  ELFFileBase *SymFile = nullptr;
> +
> +  for (const std::unique_ptr<ObjectFileBase> &F : S.getObjectFiles()) {
> +    const auto &File = cast<ObjectFile<ELFT>>(*F);
> +    Elf_Sym_Range Syms = File.getObj()->symbols(File.getSymbolTable());
> +    if (&SymE > Syms.begin() && &SymE < Syms.end())
> +      SymFile = F.get();
> +  }
> +  if (SymFile)
> +    error(Twine("undefined symbol: ") + Sym.getName() + " in " +
> +          SymFile->getName());
> +  else
> +    error(Twine("undefined symbol: ") + Sym.getName());
>

Under what conditions can we get to here? Internal linker generated symbols?

-- Sean Silva


> +}
> +
>  // Create output section objects and add them to OutputSections.
>  template <class ELFT> void Writer<ELFT>::createSections() {
>    SmallDenseMap<SectionKey<ELFT::Is64Bits>, OutputSection<ELFT> *> Map;
> @@ -331,7 +352,7 @@ template <class ELFT> void Writer<ELFT>:
>      StringRef Name = P.first;
>      SymbolBody *Body = P.second->Body;
>      if (Body->isStrongUndefined())
> -      error(Twine("undefined symbol: ") + Name);
> +      undefError<ELFT>(Symtab, *Body);
>
>      if (auto *C = dyn_cast<DefinedCommon<ELFT>>(Body))
>        CommonSymbols.push_back(C);
>
> Modified: lld/trunk/test/elf2/undef.s
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf2/undef.s?rev=248382&r1=248381&r2=248382&view=diff
>
> ==============================================================================
> --- lld/trunk/test/elf2/undef.s (original)
> +++ lld/trunk/test/elf2/undef.s Wed Sep 23 09:37:01 2015
> @@ -1,6 +1,6 @@
>  # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
>  # RUN: not lld -flavor gnu2 %t -o %t2 2>&1 | FileCheck %s
> -# CHECK: undefined symbol: foo
> +# CHECK: undefined symbol: foo in {{.*}}
>  # REQUIRES: x86
>
>    .globl _start;
>
>
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