[llvm] [X86] EltsFromConsecutiveLoads - recognise reverse load patterns. (PR #168706)

[Nico Weber via llvm-commits]

nico wrote:

Hello, this makes

```
bin/clang -fprofile-generate -fno-strict-overflow --target=x86_64-apple-macos -O2 -c foo.i 
```

go from compiling in 0.3s to not compiling within 4 minutes on my machine.

Please take a look and revert for now if it takes a while to fix.

[foo.i.zip](https://github.com/user-attachments/files/23940958/foo.i.zip)


https://github.com/llvm/llvm-project/pull/168706