Have the integrated assembler give an error if $1 is used as an identifier in
an expression.  Currently this bug causes the line to be ignored in a
release build and an assert in a debug build.

rdar://13062484


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173195 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 7d4b4d8..b5f51d8 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -734,7 +734,9 @@
 ///  primaryexpr ::= '.'
 ///  primaryexpr ::= ~,+,- primaryexpr
 bool AsmParser::ParsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
-  switch (Lexer.getKind()) {
+  SMLoc FirstTokenLoc = getLexer().getLoc();
+  AsmToken::TokenKind FirstTokenKind = Lexer.getKind();
+  switch (FirstTokenKind) {
   default:
     return TokError("unknown token in expression");
   // If we have an error assume that we've already handled it.
@@ -750,8 +752,11 @@
   case AsmToken::String:
   case AsmToken::Identifier: {
     StringRef Identifier;
-    if (ParseIdentifier(Identifier))
+    if (ParseIdentifier(Identifier)) {
+      if (FirstTokenKind == AsmToken::Dollar)
+        return Error(FirstTokenLoc, "invalid token in expression");
       return true;
+    }
 
     EndLoc = SMLoc::getFromPointer(Identifier.end());