NCG: Unreachable incorrect code in `outOfLineCmmOp`
Summary
Certain MachOps are implemented by calls to C libs.
However we have code in this function which:
- Implements emmision for a call which is never used (we will always generate inline code).
- If we were to use the call the symbol name would be incorrect.
As far as I can tell that's the case for these atomics
MO_AtomicRMW _ _ -> fsLit "atomicrmw"
MO_AtomicRead _ -> fsLit "atomicread"
MO_AtomicWrite _ -> fsLit "atomicwrite"
MO_Cmpxchg _ -> fsLit "cmpxchg"
There were all added in the same commit so that makes sense. They should use the labels in fashion like clzLabel does.