https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86204

            Bug ID: 86204
           Summary: [9 Regression] wrong strlen result after prior strnlen
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

A bug in the strnlen() implementation committed in r261705 lets a strnlen()
result be substituted for the result of subsequent calls to strlen() with the
same argument:

$ cat c.c && gcc -O2 -Wall -Wextra -fdump-tree-optimized=/dev/stdout c.c &&
./a.out
char a[4] = "123";

int main (void)
{
  unsigned n0 = __builtin_strnlen (a, 1);
  unsigned n1 = __builtin_strlen (a);

  if (n0 != 1 || n1 != 3)
    __builtin_abort ();
}

;; Function main (main, funcdef_no=0, decl_uid=1899, cgraph_uid=1,
symbol_order=1) (executed once)

main ()
{
  <bb 2> [count: 0]:
  __builtin_abort ();

}


Aborted (core dumped)

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