icc 17.0.1 crashes on valid C code at -Os and above on x86_64-linux-gnu

Compiler version and platform: 

Intel(R) C Intel(R) 64 Compiler for applications running on Intel(R) 64, Version 17.0.1.132 Build 20161005 

$ icc -O1 -c small.c
$
$ icc -Os -c small.c": internal error: 0_76

compilation aborted for small.c (code 4)
$
$ cat small.c
int a, b;

void fn1 ()
{
  int c[4] = { 3 };
  for (; b; b++)
    {
      int i;
      c[a] = b ^ i;
    }
}
$