[llvm] IR/Verifier: Allow vector type in atomic load and store (PR #120384)

[James Y Knight via llvm-commits]

jyknight wrote:

There's a crash in AtomicExpandPass with vectors, `llc -mtriple arm-none-none` crashes on:
```
define <1 x ptr> @atomic_vec1_ptr(ptr %x) #0 {
  %ret = load atomic <1 x ptr>, ptr %x acquire, align 4
  ret <1 x ptr> %ret
}
```

```
llc: llvm/lib/IR/Instructions.cpp:2974: static llvm::CastInst *llvm::CastInst::Create(Instruction::CastOps, llvm::Value *, llvm::Type *, const llvm::Twine &, llvm::InsertPosition): Assertion `castIsValid(op, S, Ty) && "Invalid cast!"' failed.
```

Call at llvm/lib/CodeGen/AtomicExpandPass.cpp:2064:19 errors; it apparently tries to create a cast from `i32` to `<1 x ptr>` with an `inttoptr`, but that doesn't work.

A lot more test coverage than is currently present in this series is going to be needed.

https://github.com/llvm/llvm-project/pull/120384