Layer attribute parsing error

[amin1377]

After introducing the layer_low and layer_high attributes for each RR graph node (replacing the previous single layer attribute), RR graph XML files generated by earlier versions can no longer be read by VPR.

The issue occurs because older RR graph XML files still contain only the layer attribute for each node, which is no longer recognized by the XML parser. As a result, the parser either treats the attribute as missing or expects layer_low and layer_high instead of layer.

[amin1377]

@vaughnbetz, @AmirhosseinPoolad, @soheilshahrouz

[amin1377]

We can temporarily add the layer attribute back, in addition to layer_low and layer_high. The reader can be modified to assign both layer_low and layer_high to the value of layer when it is present.

However, the issue arises when writing the RR Graph, as it would then include all three attributes (layer_low, layer_high, and layer). Since the API for reading and writing RR Graph XML files is automatically generated, I’m not sure how to modify the schema so that an attribute is included only when another one does not exist.

[soheilshahrouz]

When adding layer_low and layer_high, I considered keeping the existing layer attribute, but the sanity checks became complicated. The order in which getter/setter functions for these attributes are called can vary, and if all three are optional, the logic to ensure they don't conflict with each other becomes complex.

I think the most maintainable way we can address this is to update the old files by replacing the layer attribute with these two new attributes.

[soheilshahrouz]

For 2D architectures, you can also remove the layer attribute from all nodes. layer_low and layer_high are optional with a default value of zero.

[vaughnbetz]

That seems like a reasonable solution; a small shell script could do that.