[PATCH] D63845: [WIP] Create a clang attribute that lets users specify LLVM attributes

Thu Jun 27 18:39:27 PDT 2019

jdoerfert added a comment.

In D63845#1560605 <https://reviews.llvm.org/D63845#1560605>, @aaron.ballman wrote:

> In D63845#1559995 <https://reviews.llvm.org/D63845#1559995>, @lebedev.ri wrote:
>
> > What's the target use-case here? What can't be solved with normal attributes?
>

With "normal" you mean something like `__attribute__((noescape))`? We don't have them for all attributes, I doubt we want to but I might be wrong.

>> I wonder if this should go to cfe+llvm -dev lists first, it's kinda intrusive.

This is not a review to get this in. Before anything happens an RFC will be issued and discussed. We'll use this to experiment and other people can do so as well.

>> I also wonder if all these should cause a clang diagnostic, at least under `-Wall`.

What do you mean?

>> How is versioning expected to be handled? New attribute vs old clang, and vice versa.

Unknown attributes are not necessarily a problem, they should compile fine ignoring the attribute, or am I wrong?

> Also, we already have the `annotate` attribute for passing information through to LLVM. Why do we need four different ways to do this?

I didn't know that one, e.g., it is not in https://clang.llvm.org/docs/AttributeReference.html. I glanced it in clang and it did not seem to do the same thing, thus allowing to generate LLVM-IR attributes at the different positions. If it is, we should use it instead.

Repository:
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https://reviews.llvm.org/D63845