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

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,32 @@
+# This test checks to make sure that when an instruction (%3 in the test) is 
+# moved due to matching a result of a fold of two other instructions
+# (%1, and %2 in the test) in the legalizer, the DILocation of the 
+# instruction that is moved (%3) is updated appropriately.
+
+#REQUIRES: aarch64-registered-target
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arsenm wrote:

```suggestion
```

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