[code-reflection] RFR: Fix SSABraun bug and add SSA tests

[Ruby Chen]

On Tue, 2 Sep 2025 20:30:58 GMT, Ruby Chen <duke at openjdk.org> wrote:

> Fix a bug in SSABraun where, in `tryRemoveTrivialPhi()`, a phi stored in `same` that is later deleted in a recursive `tryRemoveTrivialPhi()` call is still returned despite being deleted. 
> 
> Add five tests to TestSSA: `deadCode(), ifelseLoopNested(), violaJones(), binarySearch(),` and `quicksort()`. `violaJones()` is inspired by the method `findFeaturesKernel` in HAT kernel ViolaJones, which is the bug first presented itself.

Thanks for the pointers! I'll circle back to this PR with any ideas and/or code changes for the maps :)

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PR Comment: https://git.openjdk.org/babylon/pull/542#issuecomment-3249940629