Or, better, identifying that the machine has a primitive that is better than doing each op individually. For example, a multiply-accumulate instruction vs a multiply and separate accumulate. The source code still says "a*b+c", the compiler is just expected to infer the MAC instruction.
Yep! This is an assumed optimization when it comes to modern linear algebra compilers. New primitives go way beyond FMAs: full matrix multiplies on nvidia/Intel and outer product accumulates on Apple silicon. It’s also expected that these are used nearly optimally (or you’ve got a bug).
