message: generator: do signed math to compute 'rw', to guard against underflow
diff: @@ -1073,8 +1073,10 @@ namespace StockhamGenerator
  str += "\tfor(int i=1; i<dim; i++){\n";
  str += "\t\tupper_count *= lengths[i];\n";
  str += "\t}\n";
  - str += "\tunsigned int rw = (me < (upper_count ";
  - str += " - batch*";
  + str += "\t// do signed math to guard against underflow\n";
  + str += "\tunsigned int rw = (static_cast<int>(me) < "
  + "(static_cast<int>(upper_count) ";
  + str += " - static_cast<int>(batch)*";
  str += std::to_string(numTrans);
  str += ")*";
  str += std::to_string(workGroupSizePerTrans);
  