[llvm] CodeGen: Add RegisterClass by HwMode (PR #158269)

[Craig Topper via llvm-commits]

================
@@ -1348,6 +1381,25 @@ void AsmMatcherInfo::buildRegisterClasses(
       CI->DiagnosticType = RC.getName();
 
     RegisterClassClasses.try_emplace(Def, CI);
+    assert(CI->isRegisterClass());
+  }
+
+  unsigned RegClassByHwModeIndex = 0;
+  for (const Record *ClassByHwMode : Target.getAllRegClassByHwMode()) {
+    Classes.emplace_front();
+    ClassInfo *CI = &Classes.front();
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topperc wrote:

I think you can merge these to lines

```
ClassInfo *CI = &Classes.emplace_front()
```

https://github.com/llvm/llvm-project/pull/158269