[llvm] [IPO] Prevent removal of some convergent attr (PR #134863)

[Matt Arsenault via llvm-commits]

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Nathan =?utf-8?q?Gauër?= <brioche at google.com>,
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In-Reply-To: <llvm.org/llvm/llvm-project/pull/134863 at github.com>


https://github.com/arsenm commented:

This needs to consider external call users, but we shouldn't really need to look at all the users of the function.

I'm wondering if it's even worth removing the convergent attribute. The design is just broken. If we're going to require it to avoid failing the verifier, we probably should just never strip it. So either remove the verifier check, or never remove convergent.

We would be in a more holistically correct place if we propagated noconvergent (we could do this even prior to changing the IR default, and have the confusing convergent + noconvergent combo)

https://github.com/llvm/llvm-project/pull/134863