https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84029
--- Comment #2 from Wilco <wilco at gcc dot gnu.org> --- (In reply to Richard Biener from comment #1) > If we know the length of either argument and the other argument is properly > aligned we can do a 2, 4 or 8 byte compare upfront. Not sure how often that > happens (esp. with regard to knowing alignment to make sure there's no > page fault). Yes that is another optimization related to PR78809 where you could do multiple characters in one go when you know alignment (one of the strings must be a constant string as otherwise equality doesn't work). > Note this optimization has a code-size impact and thus should be done only > for hot code regions, eventually based on a value-profile? If codesize impact is significant it could be -O3 only. However there are not that many uses of strcmp in most applications, so if the gain is large (think naive code comparing an input string against a set of keywords like in glibc/argp/argp-parse.c), it may be worth it with -O2.
