[PATCH] D29835: Correct PressureDiff calculation in presence of subregs

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec added a comment.

In https://reviews.llvm.org/D29835#673763, @MatzeB wrote:

> I did not implement it this way yet because in general a bit in the lane mask doesn't necessarily represent 1 register pressure unit.


You are right, yet this estimation seems more correct to me. I think if/when we have targets for which this is not true we could extend TRI interface to return the estimation.

> Without a similar patch to `{increase|decrease}RegPressure()` pressure book keeping will go out of sync as well.

You are probably right, I was going to look into these places...

> I'd recomment running with `-verify-misched` when touching the regpressure code.

Thanks, added.


Repository:
  rL LLVM

https://reviews.llvm.org/D29835