[lld] r268310 - Teach Undefined symbols from which file they are created from.

Sean Silva via llvm-commits llvm-commits at lists.llvm.org
Mon May 2 14:56:21 PDT 2016


On Mon, May 2, 2016 at 2:30 PM, Rui Ueyama via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: ruiu
> Date: Mon May  2 16:30:42 2016
> New Revision: 268310
>
> URL: http://llvm.org/viewvc/llvm-project?rev=268310&view=rev
> Log:
> Teach Undefined symbols from which file they are created from.
>
> This patch increases the size of Undefined by the size of a pointer,
> but it wouldn't actually increase the size of memory that LLD uses
> because we are not allocating the exact size but the size of the
> largest SymbolBody.
>
> Modified:
>     lld/trunk/ELF/SymbolTable.cpp
>     lld/trunk/ELF/Symbols.cpp
>     lld/trunk/ELF/Symbols.h
>     lld/trunk/test/ELF/lto/combined-lto-object-name.ll
>
> Modified: lld/trunk/ELF/SymbolTable.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SymbolTable.cpp?rev=268310&r1=268309&r2=268310&view=diff
>
> ==============================================================================
> --- lld/trunk/ELF/SymbolTable.cpp (original)
> +++ lld/trunk/ELF/SymbolTable.cpp Mon May  2 16:30:42 2016
> @@ -166,7 +166,6 @@ template <class ELFT> void SymbolTable<E
>
>  // Returns a file from which symbol B was created.
>  // If B does not belong to any file, returns a nullptr.
> -// This function is slow, but it's okay as it is used only for error
> messages.
>  template <class ELFT> InputFile *SymbolTable<ELFT>::findFile(SymbolBody
> *B) {
>    // If this symbol has a definition, follow pointers in the symbol to its
>    // defining file.
> @@ -177,21 +176,8 @@ template <class ELFT> InputFile *SymbolT
>      return SS->File;
>    if (auto *BC = dyn_cast<DefinedBitcode>(B))
>      return BC->File;
> -  // If not, we might be able to find it by searching symbol tables of
> files.
> -  // This code is generally only used for undefined symbols. Note that we
> can't
> -  // rely exclusively on a file search because we may find what was
> originally
> -  // an undefined symbol that was later replaced with a defined symbol,
> and we
> -  // want to return the file that defined the symbol.
> -  for (const std::unique_ptr<ObjectFile<ELFT>> &F : ObjectFiles) {
> -    ArrayRef<SymbolBody *> Syms = F->getSymbols();
> -    if (std::find(Syms.begin(), Syms.end(), B) != Syms.end())
> -      return F.get();
> -  }
> -  for (const std::unique_ptr<BitcodeFile> &F : BitcodeFiles) {
> -    ArrayRef<Symbol *> Syms = F->getSymbols();
> -    if (std::find(Syms.begin(), Syms.end(), B->symbol()) != Syms.end())
> -      return F.get();
> -  }
> +  if (auto *U = dyn_cast<Undefined>(B))
> +    return U->File;
>    return nullptr;
>  }
>
> @@ -253,8 +239,8 @@ template <typename ELFT>
>  std::string SymbolTable<ELFT>::conflictMsg(SymbolBody *Existing,
>                                             InputFile *NewFile) {
>    StringRef Sym = Existing->getName();
> -  return demangle(Sym) + " in " + getFilename(findFile(Existing)) + " and
> " +
> -         getFilename(NewFile);
> +  return demangle(Sym) + " in " +
> getFilename(Existing->getSourceFile<ELFT>()) +
> +         " and " + getFilename(NewFile);
>  }
>
>  template <class ELFT> Symbol *SymbolTable<ELFT>::addUndefined(StringRef
> Name) {
> @@ -274,6 +260,7 @@ Symbol *SymbolTable<ELFT>::addUndefined(
>    if (WasInserted) {
>      S->Binding = Binding;
>      replaceBody<Undefined>(S, Name, StOther, Type);
> +    cast<Undefined>(S->body())->File = File;
>      return S;
>    }
>    if (Binding != STB_WEAK &&
>
> Modified: lld/trunk/ELF/Symbols.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Symbols.cpp?rev=268310&r1=268309&r2=268310&view=diff
>
> ==============================================================================
> --- lld/trunk/ELF/Symbols.cpp (original)
> +++ lld/trunk/ELF/Symbols.cpp Mon May  2 16:30:42 2016
> @@ -129,6 +129,18 @@ bool SymbolBody::isPreemptible() const {
>    return symbol()->Visibility == STV_DEFAULT;
>  }
>
> +template <class ELFT> InputFile *SymbolBody::getSourceFile() {
> +  if (auto *S = dyn_cast<DefinedRegular<ELFT>>(this))
> +    return S->Section ? S->Section->getFile() : nullptr;
> +  if (auto *S = dyn_cast<SharedSymbol<ELFT>>(this))
> +    return S->File;
> +  if (auto *S = dyn_cast<DefinedBitcode>(this))
> +    return S->File;
> +  if (auto *S = dyn_cast<Undefined>(this))
> +    return S->File;
> +  return nullptr;
> +}
> +
>  template <class ELFT>
>  typename ELFT::uint SymbolBody::getVA(typename ELFT::uint Addend) const {
>    typename ELFT::uint OutVA = getSymVA<ELFT>(*this, Addend);
> @@ -258,6 +270,11 @@ bool Symbol::includeInDynsym() const {
>           (body()->isUndefined() && Config->Shared);
>  }
>
> +template InputFile *SymbolBody::template getSourceFile<ELF32LE>();
> +template InputFile *SymbolBody::template getSourceFile<ELF32BE>();
> +template InputFile *SymbolBody::template getSourceFile<ELF64LE>();
> +template InputFile *SymbolBody::template getSourceFile<ELF64BE>();
> +
>  template uint32_t SymbolBody::template getVA<ELF32LE>(uint32_t) const;
>  template uint32_t SymbolBody::template getVA<ELF32BE>(uint32_t) const;
>  template uint64_t SymbolBody::template getVA<ELF64LE>(uint64_t) const;
>
> Modified: lld/trunk/ELF/Symbols.h
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Symbols.h?rev=268310&r1=268309&r2=268310&view=diff
>
> ==============================================================================
> --- lld/trunk/ELF/Symbols.h (original)
> +++ lld/trunk/ELF/Symbols.h Mon May  2 16:30:42 2016
> @@ -108,6 +108,10 @@ public:
>    template <class ELFT> typename ELFT::uint getThunkVA() const;
>    template <class ELFT> typename ELFT::uint getSize() const;
>
> +  // Returns the file from which the symbol was created.
> +  // For logging purpose only.
> +  template <class ELFT> InputFile *getSourceFile();
> +
>  protected:
>    SymbolBody(Kind K, StringRef Name, uint8_t StOther, uint8_t Type);
>
> @@ -259,6 +263,10 @@ public:
>    static bool classof(const SymbolBody *S) {
>      return S->kind() == UndefinedKind;
>    }
> +
> +  // The file this undefined symbol was created from.
> +  // For logging purpose only.
> +  InputFile *File = nullptr;
>  };
>
>  template <class ELFT> class SharedSymbol : public Defined {
>
> Modified: lld/trunk/test/ELF/lto/combined-lto-object-name.ll
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/lto/combined-lto-object-name.ll?rev=268310&r1=268309&r2=268310&view=diff
>
> ==============================================================================
> --- lld/trunk/test/ELF/lto/combined-lto-object-name.ll (original)
> +++ lld/trunk/test/ELF/lto/combined-lto-object-name.ll Mon May  2 16:30:42
> 2016
> @@ -11,4 +11,4 @@ define void @_start() {
>    ret void
>  }
>
> -; CHECK: undefined symbol: foo in LLD-INTERNAL-combined-lto-object
> +; CHECK: undefined symbol: foo in {{.*}}combined-lto-object-name.ll.tmp.o
>

Can you please still check that the message clearly identifies this as an
internal object? The check that you have replaced this with no longer does
so.

-- Sean Silva


>
>
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