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

[Rafael Espíndola]

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

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(
>
>
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