I don't think it's as likely as you assume. Let's say you ask the computer to implement your adder, and you feed it the results of a few dozen, or a few hundre

I don't think it's as likely as you assume. Let's say you ask the computer to implement your adder, and you feed it the results of a few dozen, or a few hundred uint32 a + uint32 b = uint32 c operations. By coincidence, however, in all of those operations, every time bit a[14] is zero, bit c[26] also happens to be zero. The computer may produce an implementation which assumes this is always the case. The computer may also reason it does not need to look at some of the input bits, if say, for all of the tests, bit b[2] == bit b[16]. It may seem that a solution with assumptions like those are more complex than a simple addition operation, and thus the computer will find the addition solution first, but "simple" is a matter of perspective. Addition requires a logic cascade through the entire number, since the carries of the lower bits must be passed to the upper bits, which requires a critical path equal to the entire length of the inputs/outputs. In searching for an implementation which satisfies the few dozen/hundred test cases you feed it, making assumptions like those in the first paragraph can drastically shorten the critical path, and require far less logic since it's ignoring much of the input. Thus algorithmically, the addition operation may be seen as more complex.