[llvm] [AArch64] Allow LDR merge with same destination register by renaming (PR #71908)

[Zhaoxuan Jiang via llvm-commits]

nocchijiang wrote:

> Have you tried running a bootstrap or the llvm-test-suite, to make sure it behaves OK?

I tested the patch by running llvm-test-suite before rebasing onto the tip of `main`. I just found that the test was broken by the [patch](https://reviews.llvm.org/D88663) landed 2 weeks ago, which is fixed by the commit I just pushed. @c-rhodes please also have a look at this to make sure I'm not breaking anything.

I'm not familiar with bootstrapping stuff. I'm working on an Apple Silicon Mac so I followed [this guide](https://llvm.org/docs/AdvancedBuilds.html#apple-clang-builds-a-more-complex-bootstrap) to build Apple clang but no luck:

```
ninja: error: unknown target 'stage2-distribution'
```


https://github.com/llvm/llvm-project/pull/71908