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

Tue Aug 25 15:32:11 PDT 2020

okura added a comment.

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.

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https://reviews.llvm.org/D86565