♻️ Refactor IR Verification Logic

[MatthiasReumann]

Description

Among other things, resolves #1752. The goal of this pull request is to simplify the verifier, while improving its performance, and make it somewhat bulletproof by explicitly stating its assumptions.

Checklist

• The pull request only contains commits that are focused and relevant to this change.
• I have added appropriate tests that cover the new/changed functionality.
• I have updated the documentation to reflect these changes.
• I have added entries to the changelog for any noteworthy additions, changes, fixes, or removals.
• I have added migration instructions to the upgrade guide (if needed).
• The changes follow the project's style guidelines and introduce no new warnings.
• The changes are fully tested and pass the CI checks.
• I have reviewed my own code changes.

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[codecov]

Codecov Report

❌ Patch coverage is 97.87234% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
mlir/lib/Support/IRVerification.cpp	97.8%	6 Missing ⚠️

📢 Thoughts on this report? Let us know!

[burgholzer]

Thanks @MatthiasReumann for working on this! 🙏🏼 much appreciated.
To be honest, I did not fully think through all of the verifier rewrites, which are quite substantial. But they do look convincing.

I just pushed some fairly minor cosmetic changes (things that CLion showed as warnings).
Other than that, I have two smaller comments inline and one bigger one here:
It is nice that the existing test suite is still running. However, that was the status quo also before this PR.
To gain some certainty that this addresses the underlying problems we have been trying to solve, it would be helpful to add at least one new test case that would have failed before this PR.

[MatthiasReumann]

@burgholzer Thanks for the review! 🙏

To gain some certainty that this addresses the underlying problems we have been trying to solve, it would be helpful to add at least one new test case that would have failed before this PR.

I've added an additional test to the qtensor-ir suite. The test fails on main but succeeds on this PR.

[burgholzer]

LGTM modulo one typo.
Feel free to resolve and merge after CI is green.