[lld] r311056 - Remove a lock and use a std::unique_ptr instead.

[David Blaikie via llvm-commits]

yeah, sounds good to me (well, unique_ptr<uint8_t[]>, I guess)

On Wed, Sep 6, 2017 at 3:01 PM Rafael Avila de Espindola <
rafael.espindola at gmail.com> wrote:

> Alternativelly it can also just be a std::unique_ptr<uint8_t>, no?
>
> Cheers,
> Rafael
>
> David Blaikie via llvm-commits <llvm-commits at lists.llvm.org> writes:
>
> > Is it really worth/necessary to indirect this vector through a
> unique_ptr?
> > Saves two words in the InputSection, I guess, in the common (not
> > compressed) case? (could save the other word too, if you used a separate
> > map to only store these things when needed)
> >
> > But maybe this is the sweet spot of convenience and memory usage. Just
> > curious/checking :)
> >
> > On Wed, Aug 16, 2017 at 5:28 PM Rui Ueyama via llvm-commits <
> > llvm-commits at lists.llvm.org> wrote:
> >
> >> Author: ruiu
> >> Date: Wed Aug 16 17:27:55 2017
> >> New Revision: 311056
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=311056&view=rev
> >> Log:
> >> Remove a lock and use a std::unique_ptr instead.
> >>
> >> We had a lock to guard BAlloc from being used concurrently, but that
> >> is not very easy to understand. This patch replaces it with a
> >> std::unique_ptr.
> >>
> >> Modified:
> >>     lld/trunk/ELF/InputSection.cpp
> >>     lld/trunk/ELF/InputSection.h
> >>
> >> Modified: lld/trunk/ELF/InputSection.cpp
> >> URL:
> >>
> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputSection.cpp?rev=311056&r1=311055&r2=311056&view=diff
> >>
> >>
> ==============================================================================
> >> --- lld/trunk/ELF/InputSection.cpp (original)
> >> +++ lld/trunk/ELF/InputSection.cpp Wed Aug 16 17:27:55 2017
> >> @@ -200,17 +200,12 @@ void InputSectionBase::uncompress() {
> >>                                                  Config->IsLE,
> >> Config->Is64));
> >>
> >>    size_t Size = Dec.getDecompressedSize();
> >> -  char *OutputBuf;
> >> -  {
> >> -    static std::mutex Mu;
> >> -    std::lock_guard<std::mutex> Lock(Mu);
> >> -    OutputBuf = BAlloc.Allocate<char>(Size);
> >> -  }
> >> -
> >> -  if (Error E = Dec.decompress({OutputBuf, Size}))
> >> +  UncompressBuf.reset(new std::vector<uint8_t>(Size));
> >> +  if (Error E = Dec.decompress({(char *)UncompressBuf->data(), Size}))
> >>      fatal(toString(this) +
> >>            ": decompress failed: " + llvm::toString(std::move(E)));
> >> -  this->Data = ArrayRef<uint8_t>((uint8_t *)OutputBuf, Size);
> >> +
> >> +  this->Data = *UncompressBuf;
> >>    this->Flags &= ~(uint64_t)SHF_COMPRESSED;
> >>  }
> >>
> >>
> >> Modified: lld/trunk/ELF/InputSection.h
> >> URL:
> >>
> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputSection.h?rev=311056&r1=311055&r2=311056&view=diff
> >>
> >>
> ==============================================================================
> >> --- lld/trunk/ELF/InputSection.h (original)
> >> +++ lld/trunk/ELF/InputSection.h Wed Aug 16 17:27:55 2017
> >> @@ -183,6 +183,11 @@ public:
> >>      assert(S % sizeof(T) == 0);
> >>      return llvm::makeArrayRef<T>((const T *)Data.data(), S /
> sizeof(T));
> >>    }
> >> +
> >> +private:
> >> +  // A pointer that owns uncompressed data if a section is compressed
> by
> >> zlib.
> >> +  // Since the feature is not used often, this is usually a nullptr.
> >> +  std::unique_ptr<std::vector<uint8_t>> UncompressBuf;
> >>  };
> >>
> >>  // SectionPiece represents a piece of splittable section contents.
> >>
> >>
> >> _______________________________________________
> >> llvm-commits mailing list
> >> llvm-commits at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
> >>
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20170906/41d12374/attachment.html>