Say a local variable is allocated a reg loaded its value from memory. Say there were many uses of local variable in IR and afterwards local variable needs to be spilled due to register pressure. We can avoid writing reg back to memory if there are no intervening updates to reg on the path where it was loaded from memory to the point where it needs to be spilled.

category:cq
theme:register-allocator
skill-level:expert
cost:medium
impact:medium