[llvm-dev] LLD COFF library: crashes when lld::coff::link is called twice

[Andrew Kelley via llvm-dev]

Hans,

Apologies for not updating the list. I went through the formal
reviews.llvm.org process, and this has already been merged into trunk, I
believe.

Regards,
Andrew

On Wed, Aug 8, 2018, 10:50 AM Hans Wennborg <hans at chromium.org> wrote:

> +Rui and Peter
>
> On Wed, Jul 25, 2018 at 8:34 AM, Andrew Kelley via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> > Here's a fix:
> >
> > --- a/lld/COFF/Driver.cpp
> > +++ b/lld/COFF/Driver.cpp
> > @@ -72,6 +72,9 @@ bool link(ArrayRef<const char *> Args, bool
> CanExitEarly,
> > raw_ostream &Diag) {
> >      exitLld(errorCount() ? 1 : 0);
> >
> >    freeArena();
> > +  ObjFile::Instances.clear();
> > +  ImportFile::Instances.clear();
> > +  BitcodeFile::Instances.clear();
> >    return !errorCount();
> >  }
> >
> > I don't know how to make a test for this, since it depends on running LLD
> > twice in the same process.
> >
> > Can I get some assistance trying to get this fix upstreamed?
> >
> > On Wed, Jul 25, 2018 at 2:18 AM, Andrew Kelley <superjoe30 at gmail.com>
> wrote:
> >>
> >> If you call lld::coff::link twice, the second time gives this backtrace:
> >>
> >>      msvcp140d.dll!00007ffc35830806()    Unknown
> >> >    zig.exe!std::_Debug_pointer<lld::coff::Chunk * __ptr64
> >> > const>(lld::coff::Chunk * const * _Ptr, const wchar_t * _File,
> unsigned int
> >> > _Line) Line 926    C++
> >>      zig.exe!std::_Debug_range2<lld::coff::Chunk * __ptr64 const *
> >> __ptr64>(lld::coff::Chunk * const * _First, lld::coff::Chunk * const *
> >> _Last, const wchar_t * _File, unsigned int _Line,
> >> std::random_access_iterator_tag __formal) Line 958    C++
> >>      zig.exe!std::_Debug_range<lld::coff::Chunk * __ptr64 const *
> >> __ptr64>(lld::coff::Chunk * const * _First, lld::coff::Chunk * const *
> >> _Last, const wchar_t * _File, unsigned int _Line) Line 968    C++
> >>      zig.exe!std::vector<lld::coff::Chunk *
> >> __ptr64,std::allocator<lld::coff::Chunk * __ptr64>
> >> >::_Insert<lld::coff::Chunk * __ptr64 const *
> >>
> __ptr64>(std::_Vector_const_iterator<std::_Vector_val<std::_Simple_types<lld::coff::Chunk
> >> *> > > _Where, lld::coff::Chunk * const * _First, lld::coff::Chunk *
> const *
> >> _Last, std::forward_iterator_tag __formal) Line 1421    C++
> >>      zig.exe!std::vector<lld::coff::Chunk *
> >> __ptr64,std::allocator<lld::coff::Chunk * __ptr64>
> >> >::insert<lld::coff::Chunk * __ptr64 const *
> >>
> __ptr64>(std::_Vector_const_iterator<std::_Vector_val<std::_Simple_types<lld::coff::Chunk
> >> *> > > _Where, lld::coff::Chunk * const * _First, lld::coff::Chunk *
> const *
> >> _Last) Line 1376    C++
> >>      zig.exe!lld::coff::SymbolTable::getChunks() Line 311    C++
> >>      zig.exe!`anonymous namespace'::Writer::createSections() Line 340
> >> C++
> >>      zig.exe!`anonymous namespace'::Writer::run() Line 288    C++
> >>      zig.exe!lld::coff::writeResult() Line 166    C++
> >>      zig.exe!lld::coff::LinkerDriver::link(llvm::ArrayRef<char const *>
> >> ArgsArr) Line 1331    C++
> >>      zig.exe!lld::coff::link(llvm::ArrayRef<char const *> Args, bool
> >> CanExitEarly, llvm::raw_ostream & Diag) Line 71    C++
> >>      zig.exe!ZigLLDLink(ZigLLVM_ObjectFormatType oformat, const char * *
> >> args, unsigned __int64 arg_count, void(*)(void *, const char *, unsigned
> >> __int64) append_diagnostic, void * context) Line 837    C++
> >>      zig.exe!zig_lld_link(ZigLLVM_ObjectFormatType oformat, const char
> * *
> >> args, unsigned __int64 arg_count, Buf * diag) Line 435    C++
> >>      zig.exe!codegen_link(CodeGen * g, const char * out_file) Line 1020
> >> C++
> >>      zig.exe!main(int argc, char * * argv) Line 909    C++
> >>      [External Code]
> >>
> >> It appears that in this code, ObjFile::Instance is garbage data:
> >>
> >> std::vector<Chunk *> SymbolTable::getChunks() {
> >>   std::vector<Chunk *> Res;
> >>   for (ObjFile *File : ObjFile::Instances) {
> >>     ArrayRef<Chunk *> V = File->getChunks();
> >>     Res.insert(Res.end(), V.begin(), V.end());
> >>   }
> >>   return Res;
> >> }
> >>
> >> When I go to the definition of ObjFile::Instances, it appears to be
> static
> >> data:
> >>
> >>   static std::vector<ObjFile *> Instances;
> >>
> >> It appears that LLD is not resetting this data between calls. On the
> other
> >> hand, lld::elf::link and lld::macho::link work no problem when called
> >> multiple times in the same process.
> >>
> >> My understanding is that there is supposed to be an arena allocator,
> which
> >> is freed here:
> >>
> >> bool link(ArrayRef<const char *> Args, bool CanExitEarly, raw_ostream
> >> &Diag) {
> >>   // ...
> >>
> >>   Driver = make<LinkerDriver>();
> >>   Driver->link(Args);
> >>
> >>   // Call exit() if we can to avoid calling destructors.
> >>   if (CanExitEarly)
> >>     exitLld(errorCount() ? 1 : 0);
> >>
> >>   freeArena();  // <------ here
> >>   return !errorCount();
> >> }
> >>
> >> Is there a simple fix for this?
> >>
> >> Downstream issue reference: https://github.com/ziglang/zig/issues/1289
> >>
> >> Thanks,
> >> Andrew
> >
> >
> >
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >
>
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