[PATCH] D129745: Fix a stack overflow in ScalarEvolution.

[Nikita Popov via Phabricator via llvm-commits]

nikic added a comment.

In D129745#3651135 <https://reviews.llvm.org/D129745#3651135>, @jreiffers wrote:

> In D129745#3651133 <https://reviews.llvm.org/D129745#3651133>, @nikic wrote:
>
>> Before doing something like this, we should evaluate compile-time impact of dropping this optimization entirely.
>
> Happy to do that. programUndefinedIfPoison looks fairly expensive on its own. I'm fairly new to this project, do you have a pointer what to run? Also, unfortunately some tests appear to depend on this optimization.

Ah sorry, my wording here was really ambiguous: By "optimization" I was referring to the compile-time optimization of combining operands from multiple add/muls, rather than just creating pairwise expressions. The preservation of nowrap flags via UB reasoning is important, and not something that can be dropped.


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https://reviews.llvm.org/D129745