[PATCH] D14273: Add a method to the BitcodeReader to parse only the identification block

[Duncan P. N. Exon Smith via llvm-commits]

> On 2015-Nov-02, at 18:10, Mehdi AMINI <mehdi.amini at apple.com> wrote:
> 
> joker.eph created this revision.
> joker.eph added reviewers: dexonsmith, rafael.
> joker.eph added a subscriber: llvm-commits.
> 
> Mimic parseTriple(); and exposes it to LTOModule.cpp
> 
> http://reviews.llvm.org/D14273
> 
> Files:
>  include/llvm/Bitcode/ReaderWriter.h
>  include/llvm/LTO/LTOModule.h
>  lib/Bitcode/Reader/BitcodeReader.cpp
>  lib/LTO/LTOModule.cpp
> 
> <D14273.39022.patch>

Aside from some weird whitespace (noted below), LGTM.

> Index: lib/Bitcode/Reader/BitcodeReader.cpp
> ===================================================================
> --- lib/Bitcode/Reader/BitcodeReader.cpp
> +++ lib/Bitcode/Reader/BitcodeReader.cpp
> @@ -5805,6 +5843,19 @@
>    return Triple.get();
>  }
>  
> +std::string
> +llvm::getBitcodeProducerString(MemoryBufferRef Buffer, LLVMContext &Context,
> +                        DiagnosticHandlerFunction DiagnosticHandler) {
> +  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(Buffer, false);
> +  BitcodeReader R(Buf.release(), Context, DiagnosticHandler);
> +  ErrorOr<std::string> ProducerString = R.parseIdentificationBlock();
> +  if (ProducerString.getError())
> +    return "";
> +  return ProducerString.get();
> +}
> +
> +
> +

Seems like two too many blank lines here.

>  // Parse the specified bitcode buffer, returning the function info index.
>  // If IsLazy is false, parse the entire function summary into
>  // the index. Otherwise skip the function summary section, and only create
> Index: include/llvm/LTO/LTOModule.h
> ===================================================================
> --- include/llvm/LTO/LTOModule.h
> +++ include/llvm/LTO/LTOModule.h
> @@ -74,6 +74,12 @@
>    static bool isBitcodeForTarget(MemoryBuffer *memBuffer,
>                                   StringRef triplePrefix);
>  
> +  /// Returns a string representing the producer identification stored in the
> +  /// bitcode, or "" if the bitcode does not contains any.
> +  ///
> +  static std::string getProducerString(MemoryBuffer *Buffer);
> +
> +

Seems like one too many blank lines here.

>    /// Create a MemoryBuffer from a memory range with an optional name.
>    static std::unique_ptr<MemoryBuffer>
>    makeBuffer(const void *mem, size_t length, StringRef name = "");
> Index: include/llvm/Bitcode/ReaderWriter.h
> ===================================================================
> --- include/llvm/Bitcode/ReaderWriter.h
> +++ include/llvm/Bitcode/ReaderWriter.h
> @@ -54,6 +54,14 @@
>    getBitcodeTargetTriple(MemoryBufferRef Buffer, LLVMContext &Context,
>                           DiagnosticHandlerFunction DiagnosticHandler = nullptr);
>  
> +
> +  /// Read the header of the specified bitcode buffer and extract just the
> +  /// producer string information. If successful, this returns a string. On
> +  /// error, this returns "".
> +  std::string
> +  getBitcodeProducerString(MemoryBufferRef Buffer, LLVMContext &Context,
> +                                 DiagnosticHandlerFunction DiagnosticHandler = nullptr);

Whitespace is strange.  clang-format?

> +
>    /// Read the specified bitcode file, returning the module.
>    ErrorOr<std::unique_ptr<Module>>
>    parseBitcodeFile(MemoryBufferRef Buffer, LLVMContext &Context,
>