Re: Improve a few appendStringInfo calls new to v18

On Fri, 11 Apr 2025 at 02:51, Nathan Bossart <nathandbossart@gmail.com> wrote:
> This probably isn't v18 material, but this reminds me of my idea to change
> appendStringInfoString() into a macro for appendBinaryStringInfo() so that
> the compiler can remove the runtime strlen() calls for string literals [0].
> In most cases, the benefits are probably negligible, but StringInfo is
> sometimes used in hot paths.
>
> [0] https://postgr.es/m/20231218164135.GA530790%40nathanxps13

That one has come up a few times. The most lengthy discussion I
remember was in [1]. It didn't come to anything, but I don't think
there were any objections to it, so maybe we should just do it.

In the thread I did some measurements of binary size increases.  For
non-compile-time consts, it does mean putting the strlen() call in the
calling function, which is a bit of overhead in terms of size.  The
macro trick I suggested should have fixed that, but I admit the macro
is a bit ugly. The macro version also still has the overhead of having
to pass the length of the string when it detects a compile-time const.

David

[1] https://postgr.es/m/flat/a0086cfc-ff0f-2827-20fe-52b591d2666c%40enterprisedb.com