Patch and Rebuild
The fastest way to believe you can change PyTorch is to watch your own
printffire.
Key Insight
Adding a simple printf inside a CUDA kernel and rebuilding lets you confirm that the code you just edited is the same code that runs when you call the op from Python.
Why This Matters
This tiny change proves the whole loop — edit C++, recompile, run from Python — works on your machine. After that, real fixes and experiments are just bigger versions of the same loop.