//
// Round pointer down to nearest word boundary and pad value with zeros before
// applying atomic OR operation to target word.
//
// *(*uint32)(ptr &^ 3) |= uint32(val) << ((3 << 3) ^ ((ptr & 3) << 3))
//
(AtomicOr8  ptr val mem)
  => (LAOfloor
       ptr
       (SLW <typ.UInt32>
         (MOVBZreg <typ.UInt32> val)
         (RXSBG <typ.UInt32> {s390x.NewRotateParams(59, 60, 3)} (MOVDconst [3<<3]) ptr))
       mem)

(AtomicCompareAndSwap64 ptr old new_ mem) => (CMPXCHGQlock ptr old new_ mem)

// Atomic memory updates.
(AtomicAnd8  ptr val mem) => (ANDBlock ptr val mem)
(AtomicAnd32 ptr val mem) => (ANDLlock ptr val mem)
(AtomicOr8   ptr val mem) => (ORBlock  ptr val mem)
(AtomicOr32  ptr val mem) => (ORLlock  ptr val mem)

// Write barrier.
(WB ...) => (LoweredWB ...)