[clang] [Clang][CodeGen][CIR][NFC] Refactor CGCXXABI classes for code sharing (PR #165078)

[Oliver Hunt via cfe-commits]

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@@ -0,0 +1,99 @@
+//===----- CXXABIShared.h - Shared C++ ABI Base Class -----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides a base class for C++ ABI functionality that can be shared
+// between LLVM IR codegen and CIR codegen.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_CODEGENSHARED_CXXABISHARED_H
+#define LLVM_CLANG_CODEGENSHARED_CXXABISHARED_H
+
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/GlobalDecl.h"
+#include "clang/AST/Mangle.h"
+#include "clang/Basic/ABI.h"
+
+namespace clang {
+class ASTContext;
+
+/// Implements C++ ABI functionality that can be shared between LLVM IR codegen
+/// and CIR codegen.
+class CXXABIShared {
+protected:
+  ASTContext &Context;
+  std::unique_ptr<MangleContext> MangleCtx;
+
+  CXXABIShared(ASTContext &Context)
+      : Context(Context), MangleCtx(Context.createMangleContext()) {}
+
+public:
+  virtual ~CXXABIShared() = default;
+
+  /// Similar to AddedStructorArgs, but only notes the number of additional
+  /// arguments.
+  struct AddedStructorArgCounts {
+    unsigned Prefix = 0;
+    unsigned Suffix = 0;
+    AddedStructorArgCounts() = default;
+    AddedStructorArgCounts(unsigned P, unsigned S) : Prefix(P), Suffix(S) {}
+    static AddedStructorArgCounts prefix(unsigned N) { return {N, 0}; }
+    static AddedStructorArgCounts suffix(unsigned N) { return {0, N}; }
+  };
+
+  /// Get the AST context.
+  ASTContext &getContext() const { return Context; }
+
+  /// Gets the mangle context.
+  MangleContext &getMangleContext() { return *MangleCtx; }
+
+  /// Determine whether there's something special about the rules of
+  /// the ABI tell us that 'this' is a complete object within the
+  /// given function.  Obvious common logic like being defined on a
+  /// final class will have been taken care of by the caller.
+  virtual bool isThisCompleteObject(GlobalDecl GD) const = 0;
+
+  /// Returns true if the most-derived return value should be returned.
+  virtual bool hasMostDerivedReturn(GlobalDecl GD) const { return false; }
+
+  /// Return whether the given global decl needs a VTT parameter.
+  virtual bool NeedsVTTParameter(GlobalDecl GD) const { return false; }
----------------
ojhunt wrote:

Oh, sorry, this is method names, not variables - I think we should match the clang style, but at this point I don't know what that actually is for method names :D

(@AaronBallman what is the correct case convention?)

https://github.com/llvm/llvm-project/pull/165078