[PATCH] D101546: [AMDGPU] Fix v_swap_b32 formation on physical registers

Thu Apr 29 10:25:04 PDT 2021

arsenm added a comment.

In D101546#2726096 <https://reviews.llvm.org/D101546#2726096>, @foad wrote:

> In D101546#2726051 <https://reviews.llvm.org/D101546#2726051>, @arsenm wrote:
>
>> We don't need to rely on kill flags (and in fact should not, since they are semi-deprecated). We should be using liveness scans starting from the bottom of the block which do not need kill flags
>
> I'm not relying on the kill flag being present for correctness, I'm just taking advantage of it if it does happen to be there (and assuming that it is correct if it is present). If kill flags are not present then I guess you'd need to run MachineDCE again afterwards to clean up.

I don't mean rely on for correctness, I mean use at all. Ideally we should be working to eliminate dependence on kill flags for optimizations.

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  https://reviews.llvm.org/D101546/new/

https://reviews.llvm.org/D101546