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

[Hannes Greule]

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 trivial phi is not removed from its own user list before `phi.replaceBy(same, this)` is called to replace all users of the trivial phi.  
> 
> Add five tests to TestSSA: `deadCode(), ifelseLoopNested(), violaJones(), binarySearch(),` and `quicksort()`. `violaJones()` is inspired by the method `findFeaturesKernel` in HAT kernel ViolaJones.

Hi, it's not obvious to me what the bug is. The `replaceBy` method has the `user == this` check; what's the difference to removing itself before? And is the returned list wrong, or why aren't you using it anymore?

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PR Comment: https://git.openjdk.org/babylon/pull/542#issuecomment-3246778748