[llvm] [LoopVectorize][LAA] Hoist load in memory IV to allow vectorization (PR #168312)

[Felipe Magno de Almeida via llvm-commits]

felipealmeida wrote:

If you change this line:
```
typedef MyXalanVector<unsigned short> vector;
```
To:
```
typedef MyXalanVector<size_t> vector;
```

Then it will reproduce the problem even without -fno-strict-aliasing.

https://github.com/llvm/llvm-project/pull/168312