dialects: (func) Add custom syntax for func.return

[AntonLydike]

This PR:

• adds an __init__ constructor for func.Return, deprecating the old one.
• Adds custom print and parse as per MLIR docs

[AntonLydike]

The print and parse methods should be able to be lifted to riscv.Return and scf.yield and stencil.return I think. Maybe we should put them in a nice interface ReturnOpLikePrinting?

[codecov]

Codecov Report

Patch coverage: 82.22% and project coverage change: -0.02 ⚠️

Comparison is base (68f1d3a) 88.63% compared to head (a3d740b) 88.61%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1168      +/-   ##
==========================================
- Coverage   88.63%   88.61%   -0.02%     
==========================================
  Files         158      158              
  Lines       22148    22180      +32     
  Branches     3318     3326       +8     
==========================================
+ Hits        19630    19654      +24     
- Misses       1985     1990       +5     
- Partials      533      536       +3     

Impacted Files	Coverage Δ
tests/filecheck/frontend/dialects/affine.py	52.72% <ø> (ø)
tests/filecheck/frontend/dialects/func.py	76.92% <ø> (ø)
tests/filecheck/frontend/dialects/scf.py	50.57% <ø> (ø)
xdsl/frontend/code_generation.py	91.72% <66.66%> (ø)
xdsl/dialects/func.py	91.32% <78.12%> (-3.19%)	⬇️
tests/dialects/test_func.py	100.00% <100.00%> (ø)
tests/dialects/test_memref.py	100.00% <100.00%> (ø)
tests/interpreters/test_pdl_interpreter.py	90.97% <100.00%> (ø)

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[georgebisbas]

NIce

[webmiche]

LGMT 👍

[webmiche]

The print and parse methods should be able to be lifted to riscv.Return and scf.yield and stencil.return I think. Maybe we should put them in a nice interface ReturnOpLikePrinting?

It indeed seems that many dialects need such an operation to return controlflow back out of a region. Therefore, I think that would be a good idea 👍

Not for this PR though, I really like the self-containedness of this one. Maybe open a starter issue?