[llvm] [LV] Add a flag to conservatively choose a larger vector factor when maximizing bandwidth (PR #156012)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

> When the vector factor is large, pack/unpack instructions for vector registers may be required

This sounds like the cost of those wide vector instructions is calculated incorrectly, not considering the cost of the extra instructions. Could this not be fixed directly in the cost model?


https://github.com/llvm/llvm-project/pull/156012