[Bug c/107846] [13 Regression] error: result of '8000 << 8' requires 22 bits to represent, but 'short int' only has 16 bits

["pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107846

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic, needs-bisection
   Last reconfirmed|                            |2022-11-23
             Status|UNCONFIRMED                 |NEW
      Known to work|                            |11.1.0, 12.1.0, 12.2.0,
                   |                            |9.1.0
          Component|target                      |c
   Target Milestone|---                         |13.0
     Ever confirmed|0                           |1
            Summary|error: result of '8000 <<   |[13 Regression] error:
                   |8' requires 22 bits to      |result of '8000 << 8'
                   |represent, but 'short int'  |requires 22 bits to
                   |only has 16 bits            |represent, but 'short int'
                   |                            |only has 16 bits
             Target|bpf                         |

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Short testcase:

typedef unsigned short __u16;

#define ___bpf_mvb(x, b, n, m) ((__u##b)(x) << (b-(n+1)*8) >> (b-8) << (m*8))

#define ___bpf_swab16(x) ((__u16)(                      \
                          ___bpf_mvb(x, 16, 0, 1) |     \
                          ___bpf_mvb(x, 16, 1, 0)))

# define __bpf_constant_htons(x)        ___bpf_swab16(x)

static const int cfg_port = 8000;


unsigned short f(int t)
{
  if (t != __bpf_constant_htons (cfg_port))
    return 1;
  return 0;
}
--- CUT ---
This is definitely a bug in GCC though there might be a dup.
the line info is also missing ...
Note this only happens at -O1 and also a regression from GCC 12 even.