I don't know LLVM well enough, but you can play with godbolt
By example, with
https://godbolt.org/z/9Kv7oo9oK
you can see that values goes into registers (and that thank to 'lea' there is not many registers used).
And if you remove the option -O2, values are spilled on stack.
By example, with https://godbolt.org/z/9Kv7oo9oK you can see that values goes into registers (and that thank to 'lea' there is not many registers used).
And if you remove the option -O2, values are spilled on stack.