[llvm] [DA] getBackedgeTakenCount in isKnownLessThan can return CouldNotCompute (PR #162495)

[Sjoerd Meijer via llvm-commits]

sjoerdmeijer wrote:

The test case is minimal to trigger the segfault, but I've removed DL and the triple, and renamed a few variables.
Instead of return false, I do now check the base case. 

https://github.com/llvm/llvm-project/pull/162495