Enable ability to have multiple PNaCl wire format versions.

Modifies PNaCl bitcode reader/writer to accept PNaClVersion=1 as supported,
and all other versions are unsupported and unreadable. The PNaCl bitcode
reader/writer will generate appropriate messages (including what version
is unsupported if applicable).

Also allows command-line option --pnacl-version for setting the PNaClVersion
in the PNaCl bitcode writer.

Also fixes some problems on PNaCl bitcode headers, using common support to
determine when the read/written PNaCl bitcode file is valid.

BUG=None
R=jvoung@chromium.org

Review URL: https://codereview.chromium.org/19400002

1 files changed, 9 insertions, 3 deletions

diff --git a/include/llvm/Bitcode/NaCl/NaClBitcodeHeader.h b/include/llvm/Bitcode/NaCl/NaClBitcodeHeader.h
index 8febf95564..4f5f83a17a 100644
--- a/include/llvm/Bitcode/NaCl/NaClBitcodeHeader.h
+++ b/include/llvm/Bitcode/NaCl/NaClBitcodeHeader.h
@@ -151,6 +151,12 @@ public:
   /// is readable and supported.
   void InstallFields();
 
+  /// \brief Adds a field to the list of fields in a header. Takes ownership
+  /// of fields added.
+  void push_back(NaClBitcodeHeaderField *Field) {
+    Fields.push_back(Field);
+  }
+
   /// \brief Read the PNaCl bitcode header, The format of the header is:
   ///
   ///    1) 'PEXE' - The four character sequence defining the magic number.
@@ -172,9 +178,9 @@ public:
   // \brief Returns the number of bytes read to consume the header.
   size_t getHeaderSize() { return HeaderSize; }
 
-  /// \brief Returns C string describing why the header describes
-  /// an unsupported PNaCl Bitcode file. Returns 0 if supported.
-  const std::string Unsupported() const { return UnsupportedMessage; }
+  /// \brief Returns string describing why the header describes
+  /// an unsupported PNaCl Bitcode file.
+  const std::string &Unsupported() const { return UnsupportedMessage; }
 
   /// \brief Returns true if supported. That is, it can be run in the
   /// browser.