strlen calls on non-const char[] not folded

[nickdesaulniers]

Bugzilla Link	43624
Version	trunk
OS	Linux
CC	@davidbolvansky,@DougGregor,@zygoloid,@stephenhines

Extended Description

#include <stdio.h>
#include <string.h>
void f(const char *s){
char foo [] = "hello\n";
printf("%lu\n", strlen(foo));
foo[0] = '\0';
printf("%lu\n", strlen(foo));
}

https://godbolt.org/z/T1m9UM

Looks like GCC nicely determines the strlen at compile time. Seems nice to have.

[davidbolvansky]

They have a dedicated pass for string length tracking, but.. worth it? I don’t think so.

(The first case could be handled by instcombine)