On Tue, Jan 19, 2021 at 6:44 PM Gabriel Ravier via Gcc <gcc@xxxxxxxxxxx> wrote: > > On 1/19/21 12:33 PM, unlvsur unlvsur via Gcc wrote: > > I think __builtin_memmove_inline, __builtin_memset_inline can also get > > provided. > > > > That allows better performance for small size copies > > Manual tweaking like that seems a bit ridiculous except in very narrow > situations, and just letting GCC assume there is an implementation of > memset/memmove lets it do optimization based on copy size by default. I > guess there could be some value to such an extension for portably doing > such specific micro-optimizations manually, though. > > > and allowing memcpy to be usable without libc. > You can just define it yourself, don't worry, GCC won't mind (as long as > it has the correct semantics). Even for the narrow case of memmove, > which could be mildly inconvenient to implement in less than 10 lines on > a few systems that have non-trivial pointers (i.e. `source < > destination` doesn't work as expected), you're on freestanding, so you > should be able to make some kind of working implementation by using > non-standard stuff for that specific purpose. > FWIW, on x86, GCC 11 can inline all calls to memset, memcpy and memcmp with -minline-all-stringops. -- H.J.
