Re: [PATCH GCC8][04/33]Single interface finding invariant variables

[Trevor Saunders <tbsaunde at tbsaunde dot org>]

On Tue, Apr 18, 2017 at 01:58:43PM +0100, Bin.Cheng wrote:
> On Tue, Apr 18, 2017 at 1:20 PM, Trevor Saunders <tbsaunde@tbsaunde.org> wrote:
> > On Tue, Apr 18, 2017 at 10:39:30AM +0000, Bin Cheng wrote:
> >> -find_depends (tree *expr_p, int *ws ATTRIBUTE_UNUSED, void *data)
> >> +find_inv_vars_cb (tree *expr_p, int *ws ATTRIBUTE_UNUSED, void *data)
> >>  {
> >> -  bitmap *inv_vars = (bitmap *) data;
> >> +  struct walk_tree_data *wdata = (struct walk_tree_data*) data;
> >>    struct version_info *info;
> >>
> >>    if (TREE_CODE (*expr_p) != SSA_NAME)
> >>      return NULL_TREE;
> >> -  info = name_info (fd_ivopts_data, *expr_p);
> >>
> >> +  info = name_info (wdata->idata, *expr_p);
> >>    if (!info->inv_id || info->has_nonlin_use)
> >>      return NULL_TREE;
> >>
> >> -  if (!*inv_vars)
> >> -    *inv_vars = BITMAP_ALLOC (NULL);
> >> -  bitmap_set_bit (*inv_vars, info->inv_id);
> >> +  if (!*wdata->inv_vars)
> >> +    *wdata->inv_vars = BITMAP_ALLOC (NULL);
> >
> > Given below this seems to be dead and inv_vars could just be a bitmap.
> >
> >> +find_inv_vars (struct ivopts_data *data, tree *expr_p, bitmap *inv_vars)
> >> +{
> >> +  struct walk_tree_data wdata;
> >> +
> >> +  if (!inv_vars)
> >> +    return;
> >> +
> >> +  wdata.idata = data;
> >> +  wdata.inv_vars = inv_vars;
> >> +  walk_tree (expr_p, find_inv_vars_cb, &wdata, NULL);
> >
> > given this it looks like the null check of inv_vars in find_inv_vars_cb
> > is unnecessary because inv_vars must be nonnull to call walk_tree().
> Hmm, this check is for bitmap* pointer, the one in call back function
> is for bitmap pointer, right?

ah yes, you can pass a pointer to a bitmap that points to null in here
and then have a bitmap allocated.

thanks

Trev

> 
> Thanks,
> bin
> >
> > Thanks
> >
> > Trev