[PATCH] D86565: [Attributor][FIX] Do not deduce noundef for dead positions

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert added a comment.

In D86565#2237391 <https://reviews.llvm.org/D86565#2237391>, @okura wrote:

> In D86565#2237383 <https://reviews.llvm.org/D86565#2237383>, @jdoerfert wrote:
>
>> In D86565#2237339 <https://reviews.llvm.org/D86565#2237339>, @okura wrote:
>>
>>> In D86565#2237287 <https://reviews.llvm.org/D86565#2237287>, @jdoerfert wrote:
>>>
>>>> LGTM, one minor note. The test will be part of the module slice patch, I'm fairly certain this cannot be tested right now but it makes sense.
>>>
>>> Sorry, I was wrong. `CheckBBLivenessOnly` should be `false` because if it is `true` we cannot catch the assumed liveness of e.g. returned position.
>>> When I changed it to `true`, a new AAIsDead was registered in manifestation, and segfault happened. So I register them in `initialize`.
>>
>> Don't do that but query them in the update instead.
>
> I have difficulty in doing that because segfault happens when a fixpoint is indicated in `initialize` and `updateImpl` is not called even once.

TBH, I think we need to remove the assertion that you see (it should not be a segfault). And replace it with code that causes a pessimistic fixpoint after we are done with the update stage.


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