[RFC] noalias intrinsic

Hello,

Currently the noalias attribute can be applied on function parameters and return value, or via scoped alias on store.

The problem is that there is no easy way to apply the noalias attribute on a pointer that is loaded indirectly (e.g from the field of an aggregate, or from a memory location - though for this you can still use scoped alias, but they are a lot more intrusive)

The idea would be to provide some kind of intrinsic that can transform a pointer to a noalias pointer, something in the lines of:

define noalias i32* @noalias(i32 *%a) {

ret i32* %a

}

What do you think? Would it fit an intrinsic?

Alexandre

How is this different from the work that Hal has been doing:

https://reviews.llvm.org/search/query/qa3.P4sG6bA8/#R

https://llvm.org/devmtg/2017-02-04/Restrict-Qualified-Pointers-in-LLVM.pdf

Hi, Alexandre,

As Ehsan mentions, this is something we’ve been planning for a while. I’ll likely commit the patches to add the intrinsic soon. As soon as the AA implementation patches (and the patch to use the intrinsic in the inliner) finish the review process, we’ll be able to handle this effectively.

In short, yes. :slight_smile:

-Hal

Thanks for the link, exactly what I was looking for!

Amazing if this is already in a PR review.