Add a valid token check before parsing a ds directive

llvm/lib/MC/MCParser/AsmParser.cpp

bool AsmParser::parseDirectiveRealDCB(StringRef IDVal, const fltSemantics &Semantics) {
 
   return false;
 }
 
 /// parseDirectiveDS
 /// ::= .ds.{b, d, l, p, s, w, x} expression
 bool AsmParser::parseDirectiveDS(StringRef IDVal, unsigned Size) {
   SMLoc NumValuesLoc = Lexer.getLoc();
-  int64_t NumValues;
-  if (checkForValidSection() || parseAbsoluteExpression(NumValues))
-    return true;
-
-  if (NumValues < 0) {
+  if (Lexer.getKind() == AsmToken::Plus)
+    Lexer.Lex();
+  else if (Lexer.getKind() == AsmToken::Minus) {
     Warning(NumValuesLoc, "'" + Twine(IDVal) + "' directive with negative repeat count has no effect");
     return false;
   }
 
+  if (Lexer.getKind() != AsmToken::Integer)
+    return Error(NumValuesLoc, "directive only accepts integer values");
+
+  int64_t NumValues;
+  if (checkForValidSection() || parseAbsoluteExpression(NumValues))
+    return true;
+
   if (parseToken(AsmToken::EndOfStatement,
                  "unexpected token in '" + Twine(IDVal) + "' directive"))
     return true;
 
   for (uint64_t i = 0, e = NumValues; i != e; ++i)
     getStreamer().emitFill(Size, 0);
 
   return false;

llvm/test/MC/AsmParser/directive_ds.s

 
 # CHECK-ERROR: warning: '.ds' directive with negative repeat count has no effect
 TEST8:
        .ds -1
 
 # CHECK-ERROR: error: unexpected token in '.ds' directive
 TEST9:
        .ds 1 2
+
+# CHECK-ERROR: error: directive only accepts integer values
+TEST10:
+        .ds 5.0