Could type punning signed to unsigned integers make bounds checking faster by eliminating the need for >= comparison?

Question

Say I had a really performance-critical loop in my program where I need to check if a point was inside a rectangle, but I know at compile time that the lower bounds are always g

Answer 1

Yes, it's a perfectly valid optimization when you're testing a signed integer and the lower bound is zero. In fact it's such a common optimization that your compiler will almost certainly do it automatically; obfuscating your code by doing it yourself is very likely to be a pointless premature optimization.

I just tested this on GCC 4.9, and confirmed by inspecting the generated assembly code that it performs this optimization automatically at -O1 and above. I would expect all modern compilers to do the same.