[PATCH] D101701: [nofree] Refine concurrency requirements

[Nuno Lopes via Phabricator via llvm-commits]

nlopes accepted this revision.
nlopes added a comment.

>> 3. Today's `nofree` enables annotations and optimizations that the proposed change would no longer allow. I can't say for certain whether this is false, but at least the examples given so far seem to fail (the first one because you can just use the `nofree` **argument attribute** instead, and the second is discussed above in this comment).
>
> I think once I manage to explain the examples you will reconsider this point. To give you another one:
>
>   __attribute__((nosync)) // or __attribute__((assume("nosync")) or #pragma omp assume ext_no_synchronization
>   void user_code() {
>     a = malloc();
>     b = malloc();
>     unknown_function_with_a_now_nosync_call_site(a, b);
>     ...
>     free(a);
>   }

This is a good example, that shows that if the user annotates a function with nosync then inferring nofree becomes easier. So the proposed semantics doesn't require nosync, but inference can be aided by its presence (not in this patch yet).

I think all the reviewers' concerns have been addresses at this point. Please let us know if there's some remaining concern regarding the proposed semantics.
The semantics proposed in this patch makes a lot of sense to me. And to make things clear, this proposal *does not* make nofree imply nosync (nor the other way around).


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  https://reviews.llvm.org/D101701/new/

https://reviews.llvm.org/D101701