icc 17.0.1 miscompiles valid C code at -O1 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 -O0 small.c; ./a.out
1
$
$ icc -O1 small.c; ./a.out
0
$
$ cat small.c
int printf (const char *, ...);

static long a;

int foo (int b)
{
  if (0)
    if (1)
      return a;
  return b;
}

int main ()
{
  printf ("%d\n", foo (1));
  return 0;
}
$