[llvm] [LICM][MustExec] Make must-exec logic for IV condition commutative (PR #93150)

[Nikita Popov via llvm-commits]

nikic wrote:

> > I'm not sure what else can be done about that test.
> 
> Can we truncate the count? I mean, the math in howManyLessThans doesn't fit into i64, but does the actual backedge-taken count overflow 64 bits?

I think so. The BECount for `{0,+,1}<nuw> ule N` is `zext(N) + 1`, so we can't represent it in the narrow type.

https://github.com/llvm/llvm-project/pull/93150