// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Combine bitwise operation and bitwise inversion.
(AND x (NOT y)) => (ANDN x y)
(OR  x (NOT y)) => (ORN  x y)
(XOR x (NOT y)) => (XNOR x y)
(NOT (XOR x y)) => (XNOR x y)

// Fold constant shift with extension.
(SRAI [c] (MOVBreg  x)) && c <   8 => (SRAI [56+c] (SLLI <typ.Int64> [56] x))
(SRAI [c] (MOVHreg  x)) && c <  16 => (SRAI [48+c] (SLLI <typ.Int64> [48] x))
(SRAI [c] (MOVWreg  x)) && c <  32 => (SRAI [32+c] (SLLI <typ.Int64> [32] x))
(SRLI [c] (MOVBUreg x)) && c <   8 => (SRLI [56+c] (SLLI <typ.UInt64> [56] x))
(SRLI [c] (MOVHUreg x)) && c <  16 => (SRLI [48+c] (SLLI <typ.UInt64> [48] x))
(SRLI [c] (MOVWUreg x)) && c <  32 => (SRLI [32+c] (SLLI <typ.UInt64> [32] x))
(SLLI [c] (MOVBUreg x)) && c <= 56 => (SRLI [56-c] (SLLI <typ.UInt64> [56] x))
(SLLI [c] (MOVHUreg x)) && c <= 48 => (SRLI [48-c] (SLLI <typ.UInt64> [48] x))
(SLLI [c] (MOVWUreg x)) && c <= 32 => (SRLI [32-c] (SLLI <typ.UInt64> [32] x))

// Shift by zero.
(SRAI [0] x) => x
(SRLI [0] x) => x
(SLLI [0] x) => x