[Bug middle-end/106144] New: wide_int shifted_mask() and mask() do not agree

[aldyh at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106144

            Bug ID: 106144
           Summary: wide_int shifted_mask() and mask() do not agree
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: aldyh at gcc dot gnu.org
                CC: amacleod at redhat dot com, mikestump at comcast dot net,
                    rsandifo at gcc dot gnu.org
  Target Milestone: ---

A mask of 128 bits should match a shifted mask of 128 bits where the shift is
0, but the following assert is failing:

      {
        wide_int mask1 = wi::mask (128, false, 128);
        wide_int mask2 = wi::shifted_mask (0, 128, false, 128);
        mask1.dump ();
        mask2.dump ();
        gcc_assert (mask1 == mask2);
      }

The output is:

[...,0xffffffffffffffff], precision = 128
[0xffffffffffffffff,0xffffffffffffffff], precision = 128

I would expect both masks to be the same.