[PATCH] D113778: [AMDGPU] Use shift for b64 mov

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

In D113778#3127670 <https://reviews.llvm.org/D113778#3127670>, @foad wrote:

> In D113778#3127658 <https://reviews.llvm.org/D113778#3127658>, @arsenm wrote:
>
>> 64-bit shifts were quarter rate instructions last I checked, so this is slower
>
> The Write64Bit definitions in SISchedule.td suggest they are half rate on most subtargets and full rate on gfx90a.

I think that's probably wrong. Comments in performShlCombine for example say it's quarter rate


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D113778/new/

https://reviews.llvm.org/D113778