Revert r103137, fix for $ in labels. It looks like we can't actually handle this
at the token level. Consider the following horrible test case:

  a = 1
  .globl $a
  movl ($a), %eax
  movl $a, %eax
  movl $$a, %eax

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103178 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCParser/AsmLexer.cpp b/lib/MC/MCParser/AsmLexer.cpp
index f157a89..1183312 100644
--- a/lib/MC/MCParser/AsmLexer.cpp
+++ b/lib/MC/MCParser/AsmLexer.cpp
@@ -69,26 +69,16 @@
   }
 }
 
-/// LexIdentifier: [a-zA-Z_.$][a-zA-Z0-9_$.@]*
-/// LexIdentifier: .
-/// LexIdentifier: $
+/// LexIdentifier: [a-zA-Z_.][a-zA-Z0-9_$.@]*
 AsmToken AsmLexer::LexIdentifier() {
   while (isalnum(*CurPtr) || *CurPtr == '_' || *CurPtr == '$' ||
          *CurPtr == '.' || *CurPtr == '@')
     ++CurPtr;
   
   // Handle . as a special case.
-  if (CurPtr == TokStart+1)
-    if (TokStart[0] == '.')
-      return AsmToken(AsmToken::Dot, StringRef(TokStart, 1));
-
-  // Handle $ as a special case. $foo is an identifier, $42 is not.
-  if (TokStart[0] == '$' &&
-      (CurPtr-TokStart == 1 || isdigit(TokStart[1]) || TokStart[1] == '"')) {
-    CurPtr = TokStart+1;
-    return AsmToken(AsmToken::Dollar, StringRef(TokStart, 1));
-  }
-
+  if (CurPtr == TokStart+1 && TokStart[0] == '.')
+    return AsmToken(AsmToken::Dot, StringRef(TokStart, 1));
+  
   return AsmToken(AsmToken::Identifier, StringRef(TokStart, CurPtr - TokStart));
 }
 
@@ -262,8 +252,8 @@
 
   switch (CurChar) {
   default:
-    // Handle identifier: [a-zA-Z_.$][a-zA-Z0-9_$.@]*
-    if (isalpha(CurChar) || CurChar == '_' || CurChar == '.' || CurChar == '$')
+    // Handle identifier: [a-zA-Z_.][a-zA-Z0-9_$.@]*
+    if (isalpha(CurChar) || CurChar == '_' || CurChar == '.')
       return LexIdentifier();
     
     // Unknown character, emit an error.
@@ -289,6 +279,7 @@
   case '}': return AsmToken(AsmToken::RCurly, StringRef(TokStart, 1));
   case '*': return AsmToken(AsmToken::Star, StringRef(TokStart, 1));
   case ',': return AsmToken(AsmToken::Comma, StringRef(TokStart, 1));
+  case '$': return AsmToken(AsmToken::Dollar, StringRef(TokStart, 1));
   case '=': 
     if (*CurPtr == '=')
       return ++CurPtr, AsmToken(AsmToken::EqualEqual, StringRef(TokStart, 2));