[MLIR] Remove scheduling at FunctionOpInterfaces

[erick-xanadu]

Context: The apply_pass function from the frontend is capable of scheduling any MLIR pass from the frontend for a specific qnode. However, in order for the pass to succeed in its compilation, it must allow itself to be scheduled to transform a module.

Description of the Change: There is another branch that I worked on where I moved the bulk of the transformation to Patterns; however, the pattern applicators that are upstream in MLIR do not support running a single iteration of the worklist. I would like at some point to add a custom pattern applicator that doesn't fold and only does a single pass through the worklist (or take a variable). The passes as written represent a single iteration through the worklist. Running a single iteration through the worklist may not yield all full optimizations, but that's how it is currently coded. I think this is acceptable as we don't yet do a cost benefit analysis for any transformation.

Benefits: Can write the following:

import jax
import pennylane as qml

import catalyst


@qml.qjit(keep_intermediate=True)
@catalyst.passes.apply_pass("disentangle-CNOT")
@qml.qnode(qml.device("lightning.qubit", wires=2))
def foo():
    qml.Hadamard(0)
    qml.Hadamard(0)
    qml.Hadamard(1)
    qml.Hadamard(1)
    qml.CNOT(wires=[0, 1])
    return qml.state()


foo()
print(foo.mlir)

[isaacdevlugt]

Thanks @erick-xanadu! 😲 I can't speak for the implementation, so I'll leave the review here to others on the compilation team.

[dime10]

Let's target this bugfix for release :)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.67%. Comparing base (b46f05b) to head (a4c3a38).
Report is 12 commits behind head on v0.10.0-rc.

Additional details and impacted files

@@              Coverage Diff               @@
##           v0.10.0-rc    #1407      +/-   ##
==============================================
- Coverage       96.68%   96.67%   -0.01%     
==============================================
  Files              75       75              
  Lines            8266     8272       +6     
  Branches          867      870       +3     
==============================================
+ Hits             7992     7997       +5     
  Misses            221      221              
- Partials           53       54       +1     

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[github-actions]

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[dime10]

🚀

(I'm including this PR in my changelog update, so need to to do anything on that front.)

[dime10]

Just curious, what was the last commit about? :)

[erick-xanadu]

@dime10, walk is recursive. This pass is schedule on quantum ModuleOps. We never nest FunctionOpInterfaces here, so no need for that.