[Mesa-dev] [PATCH v4 106/129] nir: Rework opt_copy_prop_vars to use deref instructions

[Jason Ekstrand]

On Thu, Jun 21, 2018 at 1:03 AM, Kenneth Graunke <kenneth at whitecape.org>
wrote:

> On Thursday, May 31, 2018 10:06:47 PM PDT Jason Ekstrand wrote:
> [snip]
> > @@ -529,57 +509,55 @@ static bool
> >  load_from_deref_entry_value(struct copy_prop_var_state *state,
> >                              struct copy_entry *entry,
> >                              nir_builder *b, nir_intrinsic_instr *intrin,
> > -                            nir_deref_var *src, struct value *value)
> > +                            nir_deref_instr *src, struct value *value)
> >  {
> >     *value = entry->src;
> >
> > -   /* Walk the deref to get the two tails and also figure out if we
> need to
> > -    * specialize any wildcards.
> > -    */
> > -   bool need_to_specialize_wildcards = false;
> > -   nir_deref *entry_tail = &entry->dst->deref;
> > -   nir_deref *src_tail = &src->deref;
> > -   while (entry_tail->child && src_tail->child) {
> > -      assert(src_tail->child->deref_type ==
> entry_tail->child->deref_type);
> > -      if (src_tail->child->deref_type == nir_deref_type_array) {
> > -         nir_deref_array *entry_arr = nir_deref_as_array(entry_tail-
> >child);
> > -         nir_deref_array *src_arr = nir_deref_as_array(src_tail->
> child);
> > -
>
> I think there might be a bug here...note this condition...
>
> > -         if (src_arr->deref_array_type != nir_deref_array_type_wildcard
> &&
> > -             entry_arr->deref_array_type ==
> nir_deref_array_type_wildcard)
>
> Old: Source NOT wildcard, dest is wildcard.
>
> > -            need_to_specialize_wildcards = true;
> > -      }
> > +   b->cursor = nir_instr_remove(&intrin->instr);
> >
> > -      entry_tail = entry_tail->child;
> > -      src_tail = src_tail->child;
> > +   nir_deref_path entry_dst_path, src_path;
> > +   nir_deref_path_init(&entry_dst_path, entry->dst, state->mem_ctx);
> > +   nir_deref_path_init(&src_path, src, state->mem_ctx);
> > +
> > +   bool need_to_specialize_wildcards = false;
> > +   nir_deref_instr **entry_p = &entry_dst_path.path[1];
> > +   nir_deref_instr **src_p = &src_path.path[1];
> > +   while (*entry_p && *src_p) {
> > +      nir_deref_instr *entry_tail = *entry_p++;
> > +      nir_deref_instr *src_tail = *src_p++;
> > +
> > +      if (src_tail->deref_type == nir_deref_type_array &&
> > +          entry_tail->deref_type == nir_deref_type_array_wildcard)
>
> New: Source IS wildcard, dest is wildcard.  I think you want != on the
> source condition to match the old behavior.
>

I don't think there's a bug here.  With the old mechanism, we had
deref_type_array and then within that deref_array_type_direct, _indirect,
and _wildcard.  In the new scheme, we have deref_type_array and
deref_type_array_wildcard.  So deref_type == nir_deref_type_array in the
new translates to deref_type == nir_deref_type_array && deref_array_type !=
nir_deref_array_type_wildcard.  Does that make sense?
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