[PATCH] D124168: DeadMachineInstructionElim: Switch to using LiveRegUnits

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

In D124168#3476315 <https://reviews.llvm.org/D124168#3476315>, @MatzeB wrote:

> I don't know what the state of this is nowadays, but doesn't this risk problems with the old problem of `XMM` and `YMM` not being differentiated within the register units? Calling convention for windows says XMM registers are preserved but YMM register are clobbered. With this change we would likely register XMM and YMM as clobbered. I haven't thought things through here, is this pass still safe with this in mind?

I don't know anything about that, but shouldn't that be expressed with the existing constraints on the calls/returns anyway?


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https://reviews.llvm.org/D124168