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Re: hard_regno_nregs == 0 ?
- From: Ian Lance Taylor <iant at google dot com>
- To: DJ Delorie <dj at redhat dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: 09 Jan 2008 08:43:04 -0800
- Subject: Re: hard_regno_nregs == 0 ?
- References: <200801082013.m08KDLeU011644@greed.delorie.com>
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