Add variable names to the IR

[erick-xanadu]

We can investigate the option of passing down source code information like variable names from the frontend down to the generated ir, using MLIR's location mechanism. The additional info will make generated code more readable.

See here

[rturrado]

Hi there, can I have a look at this? Thanks!

[dime10]

Sure thing, that would be quite neat

[rturrado]

Hi everyone! A bit of an update on this issue.

• I am working on this local branch: main...rturrado:catalyst:issue_1714_add_variable_names_to_the_ir
• I've managed to add the names of the parameters of a JIT function to its MLIR module, but I don't think that that information is yet correctly consumed by quantum-opt.
• Variable names as they appear in the source code, e.g., a Python program, are stripped out of the JAXPR (replaced by a, b...). I've asked here if the source code information could be kept in a JAXPR, but I haven't got any answer yet, nor have I found in the JAX documentation a way of doing it.
• A possible solution would be to take control of the JAXPR generation, and implement a custom tracer, as explained here. I don't know if this approach would also let us add name location information for function local variables (on top of parameter names). But this solution looks quite overkill.
• An aside TODO: update print_mlir so that it prints the name location information (for example by adding a use_nameloc optional parameter). Actually, if this is also done for the mlir property, it may be the fix for consumers of an MLIR string to properly make use of the name location information.

[rturrado]

Should we close this issue? It was merged as part of PR #2054.