hard_regno_nregs == 0 ?

[DJ Delorie]

In rtlanal.c we have these lines:

  nregs_ymode = hard_regno_nregs[xregno][ymode];
  ...
      && (GET_MODE_SIZE (ymode) % nregs_ymode) == 0)

The m32c cc1 crashes here because xregno is 1 and ymode is QI, and
register 1 cannot hold a QI value (there are no QImode ops that take
that register), so hard_regno_nregs[1][QI] is zero, which causes a
SIGFPE.

Which assumption is wrong?  That hard_regno_nregs can be zero (m32c),
or that hard_regno_nregs will never be zero (rtlanal)?