On ARM we

I see that StoreInstanceFieldInstr takes care to reserve it, but StoreStaticFieldInstr and StoreIndexedInstr does not seem to do the same.

Also I noticed that StoreInstanceFieldInstr has the following problem: even if ShouldEmitStoreBarrier() is false we might still emit a store barrier - because this might be an unboxed store (e.g. obj.field = 2.0) in which case we don't need a store barrier for the value, but we need a store barrier for the temporary box - this means that LR needs to be blocked for these cases as well.

I think StoreIntoObject on ARM needs to assert that object != LR - to make sure that we catch any remaining cases where this does not hold.

[I am marking this as a P0 because this might lead to hard to debug issues where LR is overwritten with strange values]