http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58240
--- Comment #7 from shiyan <shiyan2016 at 126 dot com> --- (In reply to Marc Glisse from comment #4) > -fno-builtin (or some better such option)? > strncmp is a standard function, your code redefining it has undefined > behavior. gcc optimizes based on the standard behavior of the function. Thank you for the suggestion. Yes, I know -fno-builtin can work around it. I can think of many possible ways to work around it....but whatever, it is a bug. As I known, redefining a function (override?) is not supported in standard C, but first most of compiler supports this including GCC itself and second it should behaviour consistently as a compiler. It is really crazy that it will not work when N=1 only. Also, all other mainstream compiler can work well. And it cannot work with -O0 also, which means it is not an optimization of code generation. Maybe it just replace strncmp(s1, s2, 1) with (*s1-*s2), I am not sure of the implementation, but maybe it just do something like this. Thanks, Shiyan
