On Sun, 7 May 2023, Jeff Law wrote:
>
>
> On 5/6/23 19:55, Li, Pan2 wrote:
> > It looks like we cannot simply swap the code and mode in rtx_def, the code
> > may have to be the same bits as the tree_code in tree_base. Or we will meet
> > ICE like below.
> >
> > rtx_def code 16 => 8 bits.
> > rtx_def mode 8 => 16 bits.
> >
> > static inline decl_or_value
> > dv_from_value (rtx value)
> > {
> > decl_or_value dv;
> > dv = value;
> > gcc_checking_assert (dv_is_value_p (dv)); <= ICE
> > return dv;
> Ugh. We really just need to fix this code. It assumes particular structure
> layouts and that's just wrong/dumb.
Well, it's a neat trick ... we just need to adjust it to
static inline bool
dv_is_decl_p (decl_or_value dv)
{
return !dv || (int) GET_CODE ((rtx) dv) != (int) VALUE;
}
I think (and hope for the 'decl' case the bits inspected are never
'VALUE'). Of course the above stinks from a TBAA perspective ...
Any "real" fix would require allocating storage for a discriminator
and thus hurt the resource constrained var-tracking a lot.
Richard.
