[llvm] r216915 - Fix left shifts by too large exponents in MCParser

[Alexey Samsonov]

Author: samsonov
Date: Tue Sep  2 12:25:29 2014
New Revision: 216915

URL: http://llvm.org/viewvc/llvm-project?rev=216915&view=rev
Log:
Fix left shifts by too large exponents in MCParser
(which happened only on error recovery path).

This bug was reported by UBSan.

Modified:
    llvm/trunk/lib/MC/MCParser/AsmParser.cpp

Modified: llvm/trunk/lib/MC/MCParser/AsmParser.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCParser/AsmParser.cpp?rev=216915&r1=216914&r2=216915&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCParser/AsmParser.cpp (original)
+++ llvm/trunk/lib/MC/MCParser/AsmParser.cpp Tue Sep  2 12:25:29 2014
@@ -2601,13 +2601,14 @@ bool AsmParser::parseDirectiveFill() {
   if (!isUInt<32>(FillExpr) && FillSize > 4)
     Warning(ExprLoc, "'.fill' directive pattern has been truncated to 32-bits");
 
-  int64_t NonZeroFillSize = FillSize > 4 ? 4 : FillSize;
-  FillExpr &= ~0ULL >> (64 - NonZeroFillSize * 8);
-
-  for (uint64_t i = 0, e = NumValues; i != e; ++i) {
-    getStreamer().EmitIntValue(FillExpr, NonZeroFillSize);
-    if (NonZeroFillSize < FillSize)
-      getStreamer().EmitIntValue(0, FillSize - NonZeroFillSize);
+  if (NumValues > 0) {
+    int64_t NonZeroFillSize = FillSize > 4 ? 4 : FillSize;
+    FillExpr &= ~0ULL >> (64 - NonZeroFillSize * 8);
+    for (uint64_t i = 0, e = NumValues; i != e; ++i) {
+      getStreamer().EmitIntValue(FillExpr, NonZeroFillSize);
+      if (NonZeroFillSize < FillSize)
+        getStreamer().EmitIntValue(0, FillSize - NonZeroFillSize);
+    }
   }
 
   return false;