[llvm] [AMDGPU] Do not forward reserved aperture registers into wider copies (PR #220517)

[Matt Arsenault via llvm-commits]

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@@ -1189,6 +1189,15 @@ void SIInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
 
   ArrayRef<int16_t> SubIndices = RI.getRegSplitParts(RC, EltSize);
 
+  // Report rather than assert if a register is missing a required subreg.
+  for (int16_t SubIdx : SubIndices) {
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arsenm wrote:

Move to verifier error?

https://github.com/llvm/llvm-project/pull/220517