[llvm] [LV][VPlan] Reduce register usage of VPEVLBasedIVPHIRecipe. (PR #154482)

[Elvis Wang via llvm-commits]

ElvisWang123 wrote:

> Makes sense to me. This might be useful for #144520. Have you been enabling max-bandwidth downstream?

Actually we don't enable maximum-bandwidth  downstream. 
This is founded by regressions in downstream when the vplan-based register pressure model always enabled previously (now need maximum-bandwidth to enable it).

https://github.com/llvm/llvm-project/pull/154482