(ZeroExt8to(16|32|64) ...) => (MOVBZreg ...)
(ZeroExt16to(32|64) ...) => (MOVHZreg ...)
(ZeroExt32to64 ...) => (MOVWZreg ...)

(Trunc(16|32|64)to8 <t> x) && t.IsSigned() => (MOVBreg x)
(Trunc(16|32|64)to8  x) => (MOVBZreg x)
(Trunc(32|64)to16 <t> x) && t.IsSigned() => (MOVHreg x)
(Trunc(32|64)to16 x) => (MOVHZreg x)
(Trunc64to32 <t> x) && t.IsSigned() => (MOVWreg x)
(Trunc64to32 x) => (MOVWZreg x)

// Lowering constants

(Abs         ...) => (FABSD   ...)
(Sqrt        ...) => (FSQRTD  ...)
(Ceil        ...) => (FRINTPD ...)
(Floor       ...) => (FRINTMD ...)
(Round       ...) => (FRINTAD ...)
(RoundToEven ...) => (FRINTND ...)
(Trunc       ...) => (FRINTZD ...)
(FMA       x y z) => (FMADDD z x y)

(Sqrt32 ...) => (FSQRTS ...)

(Min(64|32)F ...) => (FMIN(D|S) ...)
(Max(64|32)F ...) => (FMAX(D|S) ...)

// lowering rotates

(Not (ConstBool [c])) => (ConstBool [!c])

(Floor       (Const64F [c])) => (Const64F [math.Floor(c)])
(Ceil        (Const64F [c])) => (Const64F [math.Ceil(c)])
(Trunc       (Const64F [c])) => (Const64F [math.Trunc(c)])
(RoundToEven (Const64F [c])) => (Const64F [math.RoundToEven(c)])

// Convert x * 1 to x.
(Mul(8|16|32|64)  (Const(8|16|32|64)  [1]) x) => x

(PopCount8 x) => (POPCNTL (MOVBQZX <typ.UInt32> x))

(Sqrt ...) => (SQRTSD ...)
(Sqrt32 ...) => (SQRTSS ...)

(RoundToEven x) => (ROUNDSD [0] x)
(Floor x)       => (ROUNDSD [1] x)
(Ceil x)        => (ROUNDSD [2] x)
(Trunc x)       => (ROUNDSD [3] x)

(FMA x y z) => (VFMADD231SD z x y)

// Lowering extension
// Note: we always extend to 64 bits even though some ops don't need that many result bits.
(SignExt8to16  ...) => (MOVBQSX ...)