On 5/21/22 1:52 PM, Bram Moolenaar wrote:
In a performance sensitive function I recently used vim's `and(arg1,
arg2)` and `or(arg1, arg2)` since I couldn't find `&`,`|`. Got me
wondering what the difference is between a function and vim9
instruction execution; so I was interested in taking a look at how
this instruction executes.
I guess if invoking `and()` involves setting up a stack frame then the
difference is pretty big.
Unfortunately, yes, a function call has quite a bit of overhead.
Especially now that expressions are converted to byte code when
compiling. A function call still has to handle all kinds of possible
side effects. I wonder if we can make a difference between calling a
user defined function and a builtin function, since the latter should
have predictable behavior.
My first thought was that you'd want a flag for each builtin that
indicated if it could be inlined-call in a compiled :def, when it had no
side effects. But I guess the side effects you speak of are to the
script context and it's variables. I don't know if there are any
builtins that have access to the vim9 script context, I'd guess they
shouldn't be inlined. Certainly and(), or(), xor() no side effects
anyway you look at it. I guess calling f_and() is same order of
magnitude as handling it through ISN_OPNR.
Hmm, I don't see a not(), bitwise complement, function. Called something
else? I guess you can do
val = -val - 1. Does that work on negative numbers?
-ernie
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