(AtomicExchange32 ...) => (LoweredAtomicExchange ...)
(AtomicAdd32 ...) => (LoweredAtomicAdd ...)

(AtomicCompareAndSwap32 ...) => (LoweredAtomicCas ...)

// AtomicOr8(ptr,val)  =>   LoweredAtomicOr(ptr&^3,uint32(val) << ((ptr & 3) * 8))
(AtomicOr8 ptr val mem) && !config.BigEndian =>
	(LoweredAtomicOr (AND <typ.UInt32Ptr> (MOVWconst [^3]) ptr)
		(SLL <typ.UInt32> (ZeroExt8to32 val)
			(SLLconst <typ.UInt32> [3]

(AtomicCompareAndSwap32 ptr old new mem) => (LoweredAtomicCas32 ptr (SignExt32to64 old) new mem)
(AtomicCompareAndSwap64 ...) => (LoweredAtomicCas64 ...)

// AtomicOr8(ptr,val)  =>   LoweredAtomicOr32(ptr&^3,uint32(val) << ((ptr & 3) * 8))
(AtomicOr8 ptr val mem) && !config.BigEndian =>
	(LoweredAtomicOr32 (AND <typ.UInt32Ptr> (MOVVconst [^3]) ptr)
		(SLLV <typ.UInt32> (ZeroExt8to32 val)
			(SLLVconst <typ.UInt64> [3]

		throw("cas5")
	}
	if z != 0xfffffffe {
		throw("cas6")
	}

	m = [4]byte{1, 1, 1, 1}
	atomic.Or8(&m[1], 0xf0)
	if m[0] != 1 || m[1] != 0xf1 || m[2] != 1 || m[3] != 1 {
		throw("atomicor8")
	}

	m = [4]byte{0xff, 0xff, 0xff, 0xff}
	atomic.And8(&m[1], 0x1)
	if m[0] != 0xff || m[1] != 0x1 || m[2] != 0xff || m[3] != 0xff {
		throw("atomicand8")
	}

(AtomicCompareAndSwap64 ...) => (LoweredAtomicCas64 ...)

(AtomicExchange(64|32) ...) => (LoweredAtomicExchange(64|32) ...)

// AtomicOr8(ptr,val)  => LoweredAtomicOr32(ptr&^3, uint32(val)<<((ptr&3)*8))
(AtomicOr8 ptr val mem) =>
	(LoweredAtomicOr32 (ANDI <typ.Uintptr> [^3] ptr)
		(SLL <typ.UInt32> (ZeroExt8to32 val)
			(SLLI <typ.UInt64> [3] (ANDI <typ.UInt64> [3] ptr))) mem)

	{name: "AtomicAnd8", argLength: 3, typ: "(Uint8, Mem)", hasSideEffects: true},              // *arg0 &= arg1.  arg2=memory.  Returns old contents of *arg0 and new memory.
	{name: "AtomicOr8", argLength: 3, typ: "(Uint8, Mem)", hasSideEffects: true},               // *arg0 |= arg1.  arg2=memory.  Returns old contents of *arg0 and new memory.