Basic support for macros with explicit arguments.

We still don't handle

* default values
* :req
* :vararg
* \()

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132656 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCParser/AsmLexer.cpp b/lib/MC/MCParser/AsmLexer.cpp
index a3d3a49..0c1f8f0 100644
--- a/lib/MC/MCParser/AsmLexer.cpp
+++ b/lib/MC/MCParser/AsmLexer.cpp
@@ -388,6 +388,7 @@
   case ',': return AsmToken(AsmToken::Comma, StringRef(TokStart, 1));
   case '$': return AsmToken(AsmToken::Dollar, StringRef(TokStart, 1));
   case '@': return AsmToken(AsmToken::At, StringRef(TokStart, 1));
+  case '\\': return AsmToken(AsmToken::BackSlash, StringRef(TokStart, 1));
   case '=':
     if (*CurPtr == '=')
       return ++CurPtr, AsmToken(AsmToken::EqualEqual, StringRef(TokStart, 2));