λ x : word64 * word64 * word64 * word64,
Interp-η
(λ var : Syntax.base_type → Type,
 λ '(x5, x6, x4, x2)%core,
 uint64_t x8, uint8_t x9 = Op (Syntax.SubWithGetBorrow 52 (Syntax.TWord 3) (Syntax.TWord 6) (Syntax.TWord 6) (Syntax.TWord 6) (Syntax.TWord 3)) (0x0, Return x2, 0xfffffffffffff);
 uint64_t x11, uint8_t x12 = subborrow_u51(x9, x4, 0x7ffffffffffff);
 uint64_t x14, uint8_t x15 = subborrow_u51(x12, x6, 0x7ffffffffffff);
 uint64_t x17, uint8_t x18 = subborrow_u51(x15, x5, 0x52fffffffffff);
 uint64_t x19 = (uint64_t)cmovznz(x18, 0x0, 0xffffffffffffffffL);
 uint64_t x20 = (x19 & 0xfffffffffffff);
 uint64_t x22, uint8_t x23 = Op (Syntax.AddWithGetCarry 52 (Syntax.TWord 3) (Syntax.TWord 6) (Syntax.TWord 6) (Syntax.TWord 6) (Syntax.TWord 3)) (0x0, Return x8, Return x20);
 uint64_t x24 = (x19 & 0x7ffffffffffff);
 uint64_t x26, uint8_t x27 = addcarryx_u51(x23, x11, x24);
 uint64_t x28 = (x19 & 0x7ffffffffffff);
 uint64_t x30, uint8_t x31 = addcarryx_u51(x27, x14, x28);
 uint64_t x32 = (x19 & 0x52fffffffffff);
 uint64_t x34, uint8_t _ = addcarryx_u51(x31, x17, x32);
 (Return x34, Return x30, Return x26, Return x22))
x
     : word64 * word64 * word64 * word64 → ReturnType (uint64_t * uint64_t * uint64_t * uint64_t)