gcc -O2, clang, and icc all produce the sequence:

    is_even(int):
      mov eax, edi
      not eax
      and eax, 1
      ret

I am far from a x86 expert, but I assume this version avoids contention on the flags registers and increases pipelining.

edit: my mistake, icc and clang produce the equivalent sequence "not edi; and edi, 1; mov eax, edi; ret".