Gcc builtin review: strchr, strrchr, strchrnul

[Ondřej Bílka]

On Mon, May 25, 2015 at 02:16:34PM +0200, Ondřej Bílka wrote:
> Then we have strchr, strrchr, strchrnul.
> 
> Aside from suggestion of replacing every strchr with strchrnul there are
> missed optimizations of strchr(x,0) and strchrnul(x,0). 
> 
> A strrchr(x,0) expands just to strchr(x,0) which is not enough as it
> should do full expansion to x+strlen(x).
> 
> Then you miss case when x is constant as in wordexp. 

Second problem is that you want builtin to evaluate constant strings
arguments. So why gcc could optimize away

int foo(){
  return strchr("foo", 'y');
}

but not when strchr is replaced by rawmemchr and strchrnul?

Also as for effectivity a correct primitive is strchrnul and strchr
should be expanded into it this is problem.