[clang] [CIR] Add initial support for virtual base classes (PR #155534)

[Erich Keane via cfe-commits]

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@@ -37,6 +37,12 @@ class CIRGenCXXABI {
 
   void setCXXABIThisValue(CIRGenFunction &cgf, mlir::Value thisPtr);
 
+  /// Emit the code to initialize hidden members required to handle virtual
+  /// inheritance, if needed by the ABI.
+  virtual void
+  initializeHiddenVirtualInheritanceMembers(CIRGenFunction &cgf,
+                                            const CXXRecordDecl *rd) {}
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erichkeane wrote:

Should this be pure virtual?  Or are we not expecting this to be implemented by 1 or more targets?

https://github.com/llvm/llvm-project/pull/155534