[llvm] [AMDGPU] Remove implicit definition of register group when restoring the last sub-register after a spill (PR #133986)

[Matt Arsenault via llvm-commits]

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@@ -1928,7 +1928,9 @@ void SIRegisterInfo::buildSpillLoadStore(
       MIB->setAsmPrinterFlag(MachineInstr::ReloadReuse);
     }
 
-    if (NeedSuperRegImpOperand && (IsFirstSubReg || IsLastSubReg))
+    bool IsSrcDstDef = SrcDstRegState & RegState::Define;
+    if (NeedSuperRegImpOperand &&
+        (IsFirstSubReg || (IsLastSubReg && !IsSrcDstDef)))
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arsenm wrote:

Not sure what the second condition is doing here, why isn't this just IsFirstSubReg && isDef? 

https://github.com/llvm/llvm-project/pull/133986