[llvm] [NFC][TableGen] Adopt CodeGenHelpers in SubtargetEmitter (PR #163820)

[Craig Topper via llvm-commits]

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@@ -141,7 +150,9 @@ class SubtargetEmitter : TargetFeaturesEmitter {
 /// Emit some information about the SubtargetFeature as calls to a macro so
 /// that they can be used from C++.
 void SubtargetEmitter::emitSubtargetInfoMacroCalls(raw_ostream &OS) {
-  OS << "\n#ifdef GET_SUBTARGETINFO_MACRO\n";
+  // Undef the GET_SUBTARGETINFO_MACRO macro and the end of the scope since its
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topperc wrote:

```suggestion
  // Undef the GET_SUBTARGETINFO_MACRO macro at the end of the scope since its
```

https://github.com/llvm/llvm-project/pull/163820