[llvm] [VPlan] First step towards VPlan cost modeling. (PR #92555)

[Danial Klimkin via llvm-commits]

dklimkin wrote:

Hitting the same assert issue with Tensorflow and XLA, example failing test: https://github.com/tensorflow/tensorflow/blob/master/tensorflow/compiler/tests/random_ops_test.py

https://github.com/llvm/llvm-project/pull/92555