[PATCH] D104874: [AMDGPU] Add S_MOV_B64_IMM_PSEUDO for fp constants

Thu Jun 24 15:30:04 PDT 2021

rampitec added a comment.

In D104874#2839696 <https://reviews.llvm.org/D104874#2839696>, @rampitec wrote:

> In D104874#2839691 <https://reviews.llvm.org/D104874#2839691>, @arsenm wrote:
>
>> Do you have a MIR example that fails to rematerialize as is? We split so many 64-bit operations it might be worthwhile just teaching the coalescer how to handle it
>
> We fail to rematerialize this newly added test remat-fp64-constants.ll, it shall be fairly easy to stop it before RA.
> I agree if we can teach RA to materialize subregs it would be the best, but honestly I have failed.

I have sent you the mir. If you have an idea how to dial with LiveRangeEdit::canRematerializeAt() with subregs, that would be much nicer.

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