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

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


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Comment at: llvm/lib/Target/AMDGPU/GCNRewritePartialRegUses.cpp:206
+      NewSubReg = 0;
+      LLVM_DEBUG(dbgs() << "whole reg");
+    } else {
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Seems like a missing newline?


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Comment at: llvm/lib/Target/AMDGPU/GCNRewritePartialRegUses.cpp:302-305
+  if (LIS) {
+    LIS->removeInterval(Reg);
+    LIS->createAndComputeVirtRegInterval(NewReg);
+  }
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arsenm wrote:
> 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?
Ping on this, can you just do splitSeparateComponents? I don't see why you have to mutate the existing interval 


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

https://reviews.llvm.org/D139732