[llvm] r239075 - [Object, MachO] Cache parsed MachO header in MachOObjectFile. NFC.

[David Blaikie]

On Thu, Jun 4, 2015 at 2:37 PM, Rafael Espíndola <rafael.espindola at gmail.com
> wrote:

> Is asan OK with this? I would assume that a union of
> MachO::mach_header_64 and MachO::mach_header is necessary.
>

Perhaps it'd be better to just make mach_header_64 defined:

struct mach_header_64 {
  mach_header m;
  uint32_t reserved;
};

or somesuch - then there's no weird type punning, perhaps? (though maybe
still invalid if we're trying to point to a 32 bit header from a
mach_header_64* ?)


>
> Cheers,
> Rafael
>
>
> On 4 June 2015 at 15:22, Alexey Samsonov <vonosmas at gmail.com> wrote:
> > Author: samsonov
> > Date: Thu Jun  4 14:22:03 2015
> > New Revision: 239075
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=239075&view=rev
> > Log:
> > [Object, MachO] Cache parsed MachO header in MachOObjectFile. NFC.
> >
> > Summary:
> > Avoid parsing object file each time MachOObjectFile::getHeader() is
> > called. Instead, cache the header in MachOObjectFile constructor, where
> > it's parsed anyway. In future, we must avoid constructing the object
> > at all if the header can't be parsed.
> >
> > Test Plan: regression test suite.
> >
> > Reviewers: rafael
> >
> > Subscribers: llvm-commits
> >
> > Modified:
> >     llvm/trunk/include/llvm/Object/MachO.h
> >     llvm/trunk/lib/Object/MachOObjectFile.cpp
> >
> > Modified: llvm/trunk/include/llvm/Object/MachO.h
> > URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Object/MachO.h?rev=239075&r1=239074&r2=239075&view=diff
> >
> ==============================================================================
> > --- llvm/trunk/include/llvm/Object/MachO.h (original)
> > +++ llvm/trunk/include/llvm/Object/MachO.h Thu Jun  4 14:22:03 2015
> > @@ -385,8 +385,8 @@ public:
> >
> >    MachO::any_relocation_info getRelocation(DataRefImpl Rel) const;
> >    MachO::data_in_code_entry getDice(DataRefImpl Rel) const;
> > -  MachO::mach_header getHeader() const;
> > -  MachO::mach_header_64 getHeader64() const;
> > +  const MachO::mach_header &getHeader() const;
> > +  const MachO::mach_header_64 &getHeader64() const;
> >    uint32_t
> >    getIndirectSymbolTableEntry(const MachO::dysymtab_command &DLC,
> >                                unsigned Index) const;
> > @@ -433,6 +433,7 @@ private:
> >    LoadCommandInfo getFirstLoadCommandInfo() const;
> >    LoadCommandInfo getNextLoadCommandInfo(const LoadCommandInfo &L)
> const;
> >
> > +  MachO::mach_header_64 Header64;
> >    typedef SmallVector<const char*, 1> SectionList;
> >    SectionList Sections;
> >    typedef SmallVector<const char*, 1> LibraryList;
> >
> > Modified: llvm/trunk/lib/Object/MachOObjectFile.cpp
> > URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Object/MachOObjectFile.cpp?rev=239075&r1=239074&r2=239075&view=diff
> >
> ==============================================================================
> > --- llvm/trunk/lib/Object/MachOObjectFile.cpp (original)
> > +++ llvm/trunk/lib/Object/MachOObjectFile.cpp Thu Jun  4 14:22:03 2015
> > @@ -187,7 +187,16 @@ MachOObjectFile::MachOObjectFile(MemoryB
> >        DataInCodeLoadCmd(nullptr), LinkOptHintsLoadCmd(nullptr),
> >        DyldInfoLoadCmd(nullptr), UuidLoadCmd(nullptr),
> >        HasPageZeroSegment(false) {
> > -  uint32_t LoadCommandCount = this->getHeader().ncmds;
> > +  // Parse header.
> > +  if (is64Bit())
> > +    Header64 = getStruct<MachO::mach_header_64>(this, getPtr(this, 0));
> > +  else
> > +    // First fields of MachO::mach_header_64 are the same as
> > +    // in MachO::mach_header.
> > +    *reinterpret_cast<MachO::mach_header *>(&this->Header64) =
> > +        getStruct<MachO::mach_header>(this, getPtr(this, 0));
> > +
> > +  uint32_t LoadCommandCount = getHeader().ncmds;
> >    if (LoadCommandCount == 0)
> >      return;
> >
> > @@ -1195,21 +1204,9 @@ unsigned MachOObjectFile::getArch() cons
> >
> >  Triple MachOObjectFile::getArch(const char **McpuDefault,
> >                                  Triple *ThumbTriple) const {
> > -  Triple T;
> > -  if (is64Bit()) {
> > -    MachO::mach_header_64 H_64;
> > -    H_64 = getHeader64();
> > -    T = MachOObjectFile::getArch(H_64.cputype, H_64.cpusubtype,
> McpuDefault);
> > -    *ThumbTriple = MachOObjectFile::getThumbArch(H_64.cputype,
> H_64.cpusubtype,
> > -                                                 McpuDefault);
> > -  } else {
> > -    MachO::mach_header H;
> > -    H = getHeader();
> > -    T = MachOObjectFile::getArch(H.cputype, H.cpusubtype, McpuDefault);
> > -    *ThumbTriple = MachOObjectFile::getThumbArch(H.cputype,
> H.cpusubtype,
> > -                                                 McpuDefault);
> > -  }
> > -  return T;
> > +  const auto &Header = getHeader();
> > +  *ThumbTriple = getThumbArch(Header.cputype, Header.cpusubtype,
> McpuDefault);
> > +  return getArch(Header.cputype, Header.cpusubtype, McpuDefault);
> >  }
> >
> >  relocation_iterator MachOObjectFile::section_rel_begin(unsigned Index)
> const {
> > @@ -2164,12 +2161,15 @@ MachOObjectFile::getDice(DataRefImpl Rel
> >    return getStruct<MachO::data_in_code_entry>(this, P);
> >  }
> >
> > -MachO::mach_header MachOObjectFile::getHeader() const {
> > -  return getStruct<MachO::mach_header>(this, getPtr(this, 0));
> > +const MachO::mach_header &MachOObjectFile::getHeader() const {
> > +  // First fields of MachO::mach_header_64 are the same as
> > +  // in MachO::mach_header.
> > +  return *reinterpret_cast<const MachO::mach_header *>(&this->Header64);
> >  }
> >
> > -MachO::mach_header_64 MachOObjectFile::getHeader64() const {
> > -  return getStruct<MachO::mach_header_64>(this, getPtr(this, 0));
> > +const MachO::mach_header_64 &MachOObjectFile::getHeader64() const {
> > +  assert(is64Bit());
> > +  return Header64;
> >  }
> >
> >  uint32_t MachOObjectFile::getIndirectSymbolTableEntry(
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20150604/b482ba98/attachment.html>