Take microcode: one human-visible instruction gets implemented by many microcoded instructions.
With jets, a string of many very simple human-visible instructions gets translated to just a few actual machine instructions.
So it's the opposite in the sense that a microcoded system expands each instruction you write, while a jet system contracts strings of the programmer's instructions into more efficient code.
As one of the comments says: "The point is that jets create a particularly vicious abstraction inversion whereby a programmer must simultaneously think inside the object language and a kind of metalanguage."
To take advantage of jets, the programmer has to get the shape of the code right as well as the semantics. It's a bit like writing poetry, with the extra requirements of rhyme and meter in addition to the semantic requirements of straight prose. You have to keep an eye on what jets might match the code you write if you are going to get the required performance.
With jets, a string of many very simple human-visible instructions gets translated to just a few actual machine instructions.
So it's the opposite in the sense that a microcoded system expands each instruction you write, while a jet system contracts strings of the programmer's instructions into more efficient code.
As one of the comments says: "The point is that jets create a particularly vicious abstraction inversion whereby a programmer must simultaneously think inside the object language and a kind of metalanguage."
To take advantage of jets, the programmer has to get the shape of the code right as well as the semantics. It's a bit like writing poetry, with the extra requirements of rhyme and meter in addition to the semantic requirements of straight prose. You have to keep an eye on what jets might match the code you write if you are going to get the required performance.
ASM and microcode have none of this intricacy.