https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81772
Bug ID: 81772 Summary: Compile-time snprintf optimization Product: gcc Version: 5.4.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: bugzi...@poradnik-webmastera.com Target Milestone: --- snprintf is slow. This is caused not only by format string handling, but there is also some internal fault with string handling - see https://sourceware.org/bugzilla/show_bug.cgi?id=21905 . Because of this it would be nice if gcc could perform some compile-time optimization. The best would be to parse format string at compile time and generate appropriate code for it, so there would be no format parsing at runtime at all. However any partial optimization here would be helpful. I found that sprintf with %s format is replaced with strcpy. snprintf with %s format could be replaced with strlcpy - unfortunately is is not supported yet by gcc/glibc, so other approach is needed (or implement strlcpy/strlcat and use them :))