[PATCH] D138837: [ScheduleDAG] Support REQ_SEQUENCE unscheduling

[Filipp Zhinkin via Phabricator via llvm-commits]

fzhinkin added a comment.

In D138837#4016110 <https://reviews.llvm.org/D138837#4016110>, @barannikov88 wrote:

> Just a note.
> I see other targets just override `getRepRegClassFor` for `MVT::Untyped`. Might it be better to do the same for ARM?

@barannikov88 even if `getRepRegClassFor` will return some non-null value, `getRepRegClassCostFor` may return value that differs from `1` returned by `GetCostForDef` for `REG_SEQUENCE`, so it wouldn't be sufficient to only override `getRepRegClassFor`.

I looked at how it works for SystemZ target and `getRepRegClassFor` returns `SystemZ::ADDR128BitRegClass` for `MVT::Untyped`, but corresponding cost returned by `getRepRegClassCostFor` is `0`.

It also seems like the only targets handling `MVT::Untyped` in `getRepRegClassFor` are MIPS and SystemZ, so a change should be made not only in the ARM target, but in all other targets too.


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