That depends how far in advance of running the code you're modifying it. You could see a JIT compiler as an extreme type of SMC. Or a Monero miner - its hashing algorithm relies on running randomly generated programs.

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Pannoniae an hour ago | parent [-]

JIT and SMC are two different things because JIT is write-once-then-execute, SMC is write-many-then-execute-many. Even with reoptimisation like the JVM, you're not modifying the existing code but writing it onto a new page. That is the key difference, you're not modifying existing written-out instructions, you're creating new ones.

	▲	someonebaggy 32 minutes ago \| parent [-]
		Consider a kernel that boots on several different machines with different capabilities. Patching the call instructions at init time, to point to either one version or another of a frequently used function, saves time.