Paul Berry <stereotype...@gmail.com> writes: >[...] > In v2 of this patch, you add the following code to > fs_visitor::try_copy_propagate(): > > + /* Bail if the result of composing both strides cannot be expressed > + * as another stride. > + */ > + if (entry->src.stride != 1 && > + (inst->src[arg].stride * > + type_sz(inst->src[arg].type)) % type_sz(entry->src.type) != 0) > return false; > > I don't understand. It seems like this is trying to make sure that > (src_stride * src_type_sz) / entry_type_sz is an integer so we can later > use the factor (src_type_sz / entry_type_sz) as a multiplicative factor to > correct the stride without creating a fractional result. But I don't see > us applying this correction factor anywhere. Is there some code missing?
That isn't exactly the purpose of that check. The problem arises when you are trying to compose two regions of different base types. If the stride in bytes of 'inst->src[arg]' is not a multiple of the element size of 'entry->src' you end up with an inhomogeneous stride that can only be expressed as a two-dimensional region. Instead of adding support for two-dimensional regions (which would be hard, not very useful, and only a partial solution because then we would need to handle composition of two-dimensional regions that yield three- and four-dimensional regions as a result) I disallowed copy-propagation in that case. Thanks.
pgpWR8LOCAYGd.pgp
Description: PGP signature
_______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
