Lower spatial constants for Loopy

[ShawnL00]

Sumpy can pass SpatialConstant nodes to Loopy. Loopy’s domain-aware simplifier first handles them through map_variable. It then looks for map_spatial_constant on the parent mapper. That method is missing, causing an AttributeError.

As @inducer recommended, this converts spatial constants to ordinary variables after Sumpy’s symbolic transformations.

ChatGPT 6.1 Sol generated the implementation.

[alexfikl]

I thought mappers look through the MRO specifically for this? From inducer/pymbolic#64

Which mapper in loopy is upset about it?

[ShawnL00]

I thought mappers look through the MRO specifically for this? From inducer/pymbolic#64

Which mapper in loopy is upset about it?

@alexfikl You’re right about the MRO fallback. We hit this on a private Loopy development branch (cc @a-alveyblanc). Its helper bypasses the fallback. Sorry, I should have clarified the branch context!

@inducer, would you prefer I submit the Loopy fixes to the development repository first?

[inducer]

I'd forgotten about the MRO fallback; thanks @alexfikl. 😁

I'm not yet super familiar with @a-alveyblanc's ongoing development. Which code path hits this? Within compute or outside of it? If outside, would it be productive to add a test to upstream Loopy verifying that SpatialConstants are usable?

[ShawnL00]

@inducer This happens within compute. I talked to @a-alveyblanc, and he will help me get this fixed in the private branch.