[llvm-branch-commits] [llvm] [MIR][AMDGPU] Serialize register allocation anti-hints (PR #218073)

[Matt Arsenault via llvm-branch-commits]

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@@ -231,6 +232,9 @@ template <> struct MappingTraits<VirtualRegisterDefinition> {
     // so a plain mapOptional with an empty default would still emit the keys
     // and change every existing test's output.
     // Skip the call on output when empty to keep them off entirely.
+    if (!YamlIO.outputting() || !Reg.AntiHints.empty())
+      YamlIO.mapOptional("anti-hints", Reg.AntiHints,
+                         std::vector<FlowStringValue>());
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arsenm wrote:

```suggestion
                         {});
```

https://github.com/llvm/llvm-project/pull/218073