λ x : word64 * word64,
Interp-η
(λ var : Syntax.base_type → Type,
 λ '(x1, x2)%core,
 uint64_t x4, uint8_t x5 = subborrow_u64(0x0, 0x0, x2);
 uint64_t x7, uint8_t x8 = subborrow_u64(x5, 0x0, x1);
 uint64_t x9 = cmovznz64(x8, 0x0, 0xffffffffffffffffL);
 uint64_t x10 = (x9 & 0xffffffffffffffffL);
 uint64_t x12, uint8_t x13 = addcarryx_u64(0x0, x4, x10);
 uint64_t x14 = (x9 & 0x7fffffffffffffffL);
 uint64_t x16, uint8_t _ = addcarryx_u64(x13, x7, x14);
 (Return x16, Return x12))
x
     : word64 * word64 → ReturnType (uint64_t * uint64_t)