[llvm] [LLVM][Coroutines] Introduce TBAA metadata for coro frame object (PR #176543)

[Chuanqi Xu via llvm-commits]

ChuanqiXu9 wrote:

> (yes, I know SCEV might optimize out whatever I'm writing here, before the coros pass even, this example is just to illustrate)
> 
> ```
> Generator<int> test(int n, int x, int *p) {
>   co_yield 0
>   for (int i = 0; i != n; ++i) {
>      // CoroSplit reloads `p` and `x` inside the loop
>      // If we had C++ TBAA typing for `frame`, the load/store into `frame->p` and reload of `x` (load `&frame->x`)
>      // are MayAlias, since they are both accessing type int.
>      // but of course, the address of frame->x is never taken anywhere and p is necessarily non-aliasing with it.
>     *p += x;
>   }
> }
> ```
> 
> Regarding the TBAA roots, yes, I am just making it always use the C++ one.

What if the address of x are taken somewhere and how this PR handle that? e.g.,

```C++
void take(int &);
void take(int *&);
Generator<int> test(int n, int x, int *p) {
  co_yield 0
  take(x);
  take(p);
  for (int i = 0; i != n; ++i) {
     // CoroSplit reloads `p` and `x` inside the loop
     // If we had C++ TBAA typing for `frame`, the load/store into `frame->p` and reload of `x` (load `&frame->x`)
     // are MayAlias, since they are both accessing type int.
     // but of course, the address of frame->x is never taken anywhere and p is necessarily non-aliasing with it.
    *p += x;
  }
}
```

https://github.com/llvm/llvm-project/pull/176543