`s[0] == 'h'` isn't sufficient to guarantee that `s[3]` can be access without a segfault, so the compiler is not allowed to perform this optimization.
If you use `&` instead of `&&` (so that all array elements are accessed unconditionally), the optimization will happen: https://godbolt.org/z/KjdT16Kfb
(also note you got the endianness wrong in your hand-optimized version)
If you use `&` instead of `&&` (so that all array elements are accessed unconditionally), the optimization will happen: https://godbolt.org/z/KjdT16Kfb
(also note you got the endianness wrong in your hand-optimized version)