[llvm] [IR] Allow nofree on return values (PR #203491)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> At the same time, I don't think marking it as `noalias` would be correct -- at least it seems like this is also exposed as a builtin, so there may be multiple calls. @arsenm Does that sound right?
> 

`@llvm.amdgcn.kernarg.segment.ptr` isn't of practical use anymore, other than as an optimization implementation detail. The intrinsic which matters is `@llvm.amdgcn.implicitarg.ptr`, but the same holds for both. There will usually be multiple calls, but they are entry point invariant constants. Every call within a dispatch will return the same value and these will CSE.



https://github.com/llvm/llvm-project/pull/203491