[llvm] MCExpr-ify AMDGPU PALMetadata (PR #93236)

[Matt Arsenault via llvm-commits]

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@@ -204,18 +204,19 @@ void AMDGPUPALMetadata::setRegister(unsigned Reg, const MCExpr *Val,
       return;
   }
   auto &N = getRegisters()[MsgPackDoc.getNode(Reg)];
-  bool RegSeenInREM = REM.find(Reg) != REM.end();
+  auto ExprIt = REM.find(Reg);
+  bool RegSeenInREM = ExprIt != REM.end();
 
   if (RegSeenInREM) {
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arsenm wrote:

Don't need RegSeenInREM variable? 

https://github.com/llvm/llvm-project/pull/93236