[PATCH] D108830: [AMDGPU] Propagate defining src reg for AGPR to AGPR Copys

[Vang Thao via Phabricator via llvm-commits]

vangthao added inline comments.


================
Comment at: llvm/lib/Target/AMDGPU/GCNPreRAOptimizations.cpp:201
+          if (Def.getOpcode() == AMDGPU::V_ACCVGPR_WRITE_B32_e64) {
+            MachineOperand DefSrcMO = Def.getOperand(1);
+
----------------
arsenm wrote:
> I'm worried this might not work correctly with overlapping subregisters
> I'm worried this might not work correctly with overlapping subregisters

I added some new tests. Do they address this? If not can you give an example?


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Comment at: llvm/lib/Target/AMDGPU/GCNPreRAOptimizations.cpp:211-214
+              LIS->removeInterval(DefSrcMO.getReg());
+              LIS->removeInterval(SrcReg);
+              LIS->createAndComputeVirtRegInterval(DefSrcMO.getReg());
+              LIS->createAndComputeVirtRegInterval(SrcReg);
----------------
arsenm wrote:
> Should not need to totally trash the liveness and start over
> Should not need to totally trash the liveness and start over

Is there a way to update the liveness without trashing it?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D108830/new/

https://reviews.llvm.org/D108830