[PATCH] D139732: [AMDGPU] Add pass to rewrite partially used virtual superregisters after RenameIndependentSubregs pass with registers of minimal size (WIP)

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


================
Comment at: llvm/lib/Target/AMDGPU/GCNRewritePartialRegUses.cpp:302-305
+  if (LIS) {
+    LIS->removeInterval(Reg);
+    LIS->createAndComputeVirtRegInterval(NewReg);
+  }
----------------
vpykhtin wrote:
> arsenm wrote:
> > Can you do better than delete and recreate the liveness? Can we do this before liveness is computed?
> Liveness is required by the previous pass but this pass doesn't use it so I decided not to require it.
> 
> Liveness subranges aren't touched by this pass but some of them become main range instead of subrange. Subreg indexes and lanemasks need to be updated.
Do you only need to do splitSeparateComponents for each changed register?


Repository:
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  https://reviews.llvm.org/D139732/new/

https://reviews.llvm.org/D139732