Fix countLeadingZeros in the case that the bitwidth evenly divides the

word size. This fixes all reads of uninitialized data (buffer over read)
and makes APInt.cpp memory clean, per valgrind. The only remaining
problem is division in a few cases.

llvm-svn: 34483

llvm/lib/Support/APInt.cpp

@@ -726,7 +726,10 @@ uint32_t APInt::countLeadingZeros() const {
       }
     }
   }
-  return Count - (APINT_BITS_PER_WORD - (BitWidth % APINT_BITS_PER_WORD));
+  uint32_t remainder = BitWidth % APINT_BITS_PER_WORD;
+  if (remainder)
+    Count -= APINT_BITS_PER_WORD - remainder;
+  return Count;
 }
 
 /// countTrailingZeros - This function is a APInt version corresponding to