Terrible nitpick, but this is actually 3 operations, not instructions. On x86 you get 4:
is_leap_year_fast: imul eax, edi, 1073750999 and eax, -1073614833 cmp eax, 126977 setb al ret
is_leap_year_fast: ldr r1, .LCPI0_0 mul r0, r0, r1 ldr r1, .LCPI0_1 and r1, r0, r1 mov r0, #0 cmp r1, #126976 movwls r0, #1 bx lr .LCPI0_0: .long 1073750999 .LCPI0_1: .long 3221352463
if(is_leap_year_fast()) {...}
Terrible nitpick, but this is actually 3 operations, not instructions. On x86 you get 4:
On ARM you get a bit more due to instruction encoding: Compiler explorer reference: https://godbolt.org/z/7ajYqbT9z