[JoachimSchipper]

Modern tooling will look for correlations; (fixed) useless instructions per se don't help, since the signal can still be found in the original instructions.

However, the attacks all rely on reducing noise by combining measurements. Introducing sufficiently-long random delays or sufficiently-big variations in clock speed can make it harder to combine measurements, and can thus stop such attacks. Unfortunately, making trace alignment hard is not so much a provably-correct fix as a contest between the hardware designer's ability to be really annoying and the attacker's intuition (to find usable synchronization points) and sheer persistence.

(If you want to rely on such things, you really need to get a top-notch hardware attack lab such as Riscure to look at your countermeasures; you really want to test against an experienced attacker's intuition.)