[lld] r204291 - [ELF] Order DT_NEEDED entries by command line order.

[Rui Ueyama]

Michael,

I'll revert this change for now as it broke buildbots. I could repro it on
my local machine too.

http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-debian-fast/builds/13755/steps/test/logs/stdio


On Wed, Mar 19, 2014 at 6:28 PM, Michael J. Spencer
<bigcheesegs at gmail.com>wrote:

> Author: mspencer
> Date: Wed Mar 19 20:28:23 2014
> New Revision: 204291
>
> URL: http://llvm.org/viewvc/llvm-project?rev=204291&view=rev
> Log:
> [ELF] Order DT_NEEDED entries by command line order.
>
> With this all test-suite tests pass with lld on x86-64 Linux.
>
> Added:
>     lld/trunk/test/elf/DT_NEEDED-order.test
>     lld/trunk/test/elf/Inputs/use-shared2.x86-64
> Modified:
>     lld/trunk/lib/ReaderWriter/ELF/OutputELFWriter.h
>     lld/trunk/test/elf/Inputs/use-shared.c
>
> Modified: lld/trunk/lib/ReaderWriter/ELF/OutputELFWriter.h
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/ELF/OutputELFWriter.h?rev=204291&r1=204290&r2=204291&view=diff
>
> ==============================================================================
> --- lld/trunk/lib/ReaderWriter/ELF/OutputELFWriter.h (original)
> +++ lld/trunk/lib/ReaderWriter/ELF/OutputELFWriter.h Wed Mar 19 20:28:23
> 2014
> @@ -18,7 +18,7 @@
>  #include "lld/ReaderWriter/ELFLinkingContext.h"
>  #include "lld/ReaderWriter/Writer.h"
>
> -#include "llvm/ADT/StringSet.h"
> +#include <unordered_set>
>
>  namespace lld {
>  namespace elf {
> @@ -129,7 +129,6 @@ protected:
>    LLD_UNIQUE_BUMP_PTR(DynamicSymbolTable<ELFT>) _dynamicSymbolTable;
>    LLD_UNIQUE_BUMP_PTR(StringTable<ELFT>) _dynamicStringTable;
>    LLD_UNIQUE_BUMP_PTR(HashSection<ELFT>) _hashTable;
> -  llvm::StringSet<> _soNeeded;
>    /// @}
>  };
>
> @@ -165,6 +164,12 @@ void OutputELFWriter<ELFT>::buildStaticS
>      _symtab->addSymbol(a, ELF::SHN_UNDEF);
>  }
>
> +struct StringRefFilePairHash {
> +  std::size_t operator()(const std::pair<StringRef, const File *> &v)
> const {
> +    return llvm::hash_combine(v.first, v.second);
> +  }
> +};
> +
>  template <class ELFT>
>  void OutputELFWriter<ELFT>::buildDynamicSymbolTable(const File &file) {
>    ScopedTask task(getDefaultDomain(), "buildDynamicSymbolTable");
> @@ -176,14 +181,26 @@ void OutputELFWriter<ELFT>::buildDynamic
>            _dynamicSymbolTable->addSymbol(atom->_atom, section->ordinal(),
>                                           atom->_virtualAddr, atom);
>        }
> +  std::unordered_set<std::pair<StringRef, const File *>,
> StringRefFilePairHash>
> +    soNeeded;
>    for (const auto sla : file.sharedLibrary()) {
>      _dynamicSymbolTable->addSymbol(sla, ELF::SHN_UNDEF);
> -    _soNeeded.insert(sla->loadName());
> +    soNeeded.insert(std::make_pair(sla->loadName(), &sla->file()));
>    }
> -  for (const auto &loadName : _soNeeded) {
> +  // Sort needed entries by command line order. This is needed so the
> correct
> +  // dynamic symbol is loaded in cases where multiple dynamic libraries
> define
> +  // the same symbol.
> +  std::vector<std::pair<StringRef, const File *>> sortedSoNeeded(
> +      soNeeded.begin(), soNeeded.end());
> +  std::sort(sortedSoNeeded.begin(), sortedSoNeeded.end(),
> +            [](const std::pair<StringRef, const File *> &a,
> +               const std::pair<StringRef, const File *> &b) {
> +    return a.second->ordinal() < b.second->ordinal();
> +  });
> +  for (auto const &lib : sortedSoNeeded) {
>      Elf_Dyn dyn;
>      dyn.d_tag = DT_NEEDED;
> -    dyn.d_un.d_val = _dynamicStringTable->addString(loadName.getKey());
> +    dyn.d_un.d_val = _dynamicStringTable->addString(lib.first);
>      _dynamicTable->addEntry(dyn);
>    }
>    const auto &rpathList = _context.getRpathList();
>
> Added: lld/trunk/test/elf/DT_NEEDED-order.test
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf/DT_NEEDED-order.test?rev=204291&view=auto
>
> ==============================================================================
> --- lld/trunk/test/elf/DT_NEEDED-order.test (added)
> +++ lld/trunk/test/elf/DT_NEEDED-order.test Wed Mar 19 20:28:23 2014
> @@ -0,0 +1,14 @@
> +RUN: lld -flavor gnu -target x86_64-linux %p/Inputs/use-shared2.x86-64 \
> +RUN:   %p/Inputs/shared.so-x86-64 %p/Inputs/libundef.so -o %t -e main \
> +RUN:   --noinhibit-exec
> +RUN: lld -flavor gnu -target x86_64-linux %p/Inputs/use-shared2.x86-64 \
> +RUN:   %p/Inputs/libundef.so %p/Inputs/shared.so-x86-64 -o %t2 -e main \
> +RUN:   --noinhibit-exec
> +RUN: llvm-readobj -dynamic-table %t | FileCheck --check-prefix=ORDER1 %s
> +RUN: llvm-readobj -dynamic-table %t2 | FileCheck --check-prefix=ORDER2 %s
> +
> +ORDER1: NEEDED SharedLibrary (shared.so
> +ORDER1: NEEDED SharedLibrary (libundef.so
> +
> +ORDER2: NEEDED SharedLibrary (libundef.so
> +ORDER2: NEEDED SharedLibrary (shared.so
>
> Modified: lld/trunk/test/elf/Inputs/use-shared.c
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf/Inputs/use-shared.c?rev=204291&r1=204290&r2=204291&view=diff
>
> ==============================================================================
> --- lld/trunk/test/elf/Inputs/use-shared.c (original)
> +++ lld/trunk/test/elf/Inputs/use-shared.c Wed Mar 19 20:28:23 2014
> @@ -1,7 +1,8 @@
>  extern int i;
> +extern long long x __attribute__((weak));
>  void foo();
>
>  int main() {
>    foo();
> -  return i;
> +  return i + x;
>  }
>
> Added: lld/trunk/test/elf/Inputs/use-shared2.x86-64
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf/Inputs/use-shared2.x86-64?rev=204291&view=auto
>
> ==============================================================================
> Binary files lld/trunk/test/elf/Inputs/use-shared2.x86-64 (added) and
> lld/trunk/test/elf/Inputs/use-shared2.x86-64 Wed Mar 19 20:28:23 2014 differ
>
>
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