On Mon, Apr 07, 2025 at 09:15:04PM +0800, Zijun Hu wrote: > From: Zijun Hu <[email protected]> > > strstarts() is frequently invoked to test if a string has another string > as prefix, but its performance is degraded by the strlen() loop contained. > > Improve its performance by eliminating the strlen() loop.
So, as Andy already said: no, this is very unlikely to be a performance improvement, and if it is, you'll need to show the numbers (and likely the reason _why_, in the form of assembly output, etc). The reason this isn't going to be an improvement is because strlen($string_constant) is optimized by the compiler into a integral constant value. So you'd be replacing a potentially inline constant with an explicit function call. That will be much more expensive. With almost 300 users: $ git grep 'strstarts' | wc -l 198 Only 38 are _not_ using a string constant: $ git grep 'strstarts' | grep -v '"' | wc -l 38 Additionally, there is no "loop". strlen() of a runtime string would be evaluated once. -Kees -- Kees Cook
