ELF: Add support for the asm .version directive.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156712 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCParser/ELFAsmParser.cpp b/lib/MC/MCParser/ELFAsmParser.cpp
index ffc400b..9316bb1 100644
--- a/lib/MC/MCParser/ELFAsmParser.cpp
+++ b/lib/MC/MCParser/ELFAsmParser.cpp
@@ -64,6 +64,7 @@
     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveType>(".type");
     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveIdent>(".ident");
     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveSymver>(".symver");
+    AddDirectiveHandler<&ELFAsmParser::ParseDirectiveVersion>(".version");
     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveWeakref>(".weakref");
     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveSymbolAttribute>(".weak");
     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveSymbolAttribute>(".local");
@@ -141,6 +142,7 @@
   bool ParseDirectiveType(StringRef, SMLoc);
   bool ParseDirectiveIdent(StringRef, SMLoc);
   bool ParseDirectiveSymver(StringRef, SMLoc);
+  bool ParseDirectiveVersion(StringRef, SMLoc);
   bool ParseDirectiveWeakref(StringRef, SMLoc);
   bool ParseDirectiveSymbolAttribute(StringRef, SMLoc);
 
@@ -548,6 +550,32 @@
   return false;
 }
 
+/// ParseDirectiveVersion
+///  ::= .version string
+bool ELFAsmParser::ParseDirectiveVersion(StringRef, SMLoc) {
+  if (getLexer().isNot(AsmToken::String))
+    return TokError("unexpected token in '.version' directive");
+
+  StringRef Data = getTok().getIdentifier();
+
+  Lex();
+
+  const MCSection *Note =
+    getContext().getELFSection(".note", ELF::SHT_NOTE, 0,
+                               SectionKind::getReadOnly());
+
+  getStreamer().PushSection();
+  getStreamer().SwitchSection(Note);
+  getStreamer().EmitIntValue(Data.size()+1, 4); // namesz.
+  getStreamer().EmitIntValue(0, 4);             // descsz = 0 (no description).
+  getStreamer().EmitIntValue(1, 4);             // type = NT_VERSION.
+  getStreamer().EmitBytes(Data, 0);             // name.
+  getStreamer().EmitIntValue(0, 1);             // terminate the string.
+  getStreamer().EmitValueToAlignment(4);        // ensure 4 byte alignment.
+  getStreamer().PopSection();
+  return false;
+}
+
 /// ParseDirectiveWeakref
 ///  ::= .weakref foo, bar
 bool ELFAsmParser::ParseDirectiveWeakref(StringRef, SMLoc) {