https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78809
--- Comment #15 from Qing Zhao <qing.zhao at oracle dot com> --- (In reply to Wilco from comment 14) > The only reason we have to do a character by character comparison is because > we > cannot read beyond the end of a string. However when we know the size or > alignment we can safely process a string one word at a time. is it possible that “NULL_terminator” is in the middle of the string even though we know the size or alignment? for example: const char s[8] = “abcd\0abc”; // null byte in the middle of the string int f2(void) { return __builtin_strcmp(s, "abc") != 0; } int f3(void) { return __builtin_strcmp(s, “abc”); } can either of the above f2 or f3 been optimized to memcmp? seems not.