[llvm] Merge sourcelocation in CSEMIRBuilder::getDominatingInstrForID. (PR #90922)

[Matt Arsenault via llvm-commits]

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@@ -243,6 +243,10 @@ class MachineIRBuilder {
   }
 
 public:
+  /// This is the merged location of an instruction which is a result of a fold
+  /// in the legalizer.
+  DILocation *MergedLocation = nullptr;
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arsenm wrote:

This doesn't seem like block or function level state 

https://github.com/llvm/llvm-project/pull/90922