The assumption that the trivial solution won't be optimized out is, I think, wrong. From your experiment GCC is indeed not smart enough to do so but I would bet

The assumption that the trivial solution won't be optimized out is, I think, wrong. From your experiment GCC is indeed not smart enough to do so but I would bet that a compiler like ICC would. In this case the best is probably to use some pragmas to avoid optimizing out a statement.