Neo: What are you trying to tell me? That I can dodge "call rax"? Morpheus: No, Neo. I'm trying to tell you that when you're ready, you won't need "call rax".

Neo: What are you trying to tell me? That I can dodge "call rax"? Morpheus: No, Neo. I'm trying to tell you that when you're ready, you won't need "call rax". --- Compiler has access to optimizations that are at the higher level of abstraction than what CPU can do. For example, the compiler can eliminate the call completely (i.e. inline the function), or convert a dynamic dispatch into static (if it can prove that an object will always have a specific type at the call site), or decide where to favor small code over fast code (via profile-guided optimization), or even switch from non-optimized code (but with short start-up time) to optimized code mid-execution (tiered compilation in JITs), move computation outside loops (if it can prove that the result is the same in all iterations), and many other things...