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

[Zhendong_Su]

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 small.c; ./a.out; echo $?
0
$ 
$ icc -Os small.c; ./a.out; echo $?
255
$ 
$ cat small.c
short a = 2;

int main ()
{
  while (a)
    a -= 3;
  return a; 
}
$