hard_regno_nregs == 0 ?

[Ian Lance Taylor]

DJ Delorie <dj@redhat.com> writes:

> 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)?

I would first ask why subreg_get_info is being called with ymode ==
QImode for a hard register which can not hold QImode.  That implies
that there is a QImode value in the register, which you say is
invalid.

Ian