[llvm] [GVNSink] Fix #77415: GVNSink fails to optimize LLVM IR with debug info (PR #77419)

[Nikita Popov via llvm-commits]

nikic wrote:

Ah yes, it looks like I already discovered this once in the past:
```
commit 15fc293b11181177c9410e8715c2186bbe1390ed
Author: Nikita Popov <npopov at redhat.com>
Date:   Thu Apr 21 10:45:40 2022 +0200

    Revert "[GVNSink] Regenerate test checks (NFC)"
    
    This reverts commit 3b132300728e7ed06e59e449ceb8175305869a49.
    
    It looks like GVNSink is currently non-deterministic, due to an
    std::sort() on BasicBlock* pointers in ModelledPHI. This becomes
    visible in the generated checks.
```

I think that needs to be fixed before we can do any further changes to this pass.

https://github.com/llvm/llvm-project/pull/77419