[clang] [CIR] Build out AST consumer patterns to reach the entry point into CIRGen (PR #91007)

[Erich Keane via cfe-commits]

================
@@ -0,0 +1,59 @@
+//===- CIRGenerator.h - CIR Generation from Clang AST ---------------------===//
+//
+// 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 declares a simple interface to perform CIR generation from Clang
+// AST
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef CLANG_CIRGENERATOR_H_
+#define CLANG_CIRGENERATOR_H_
+
+#include "clang/AST/ASTConsumer.h"
+#include "clang/AST/DeclGroup.h"
+#include "clang/Basic/CodeGenOptions.h"
+#include "clang/Basic/Diagnostic.h"
+
+#include "llvm/ADT/IntrusiveRefCntPtr.h"
+#include "llvm/Support/VirtualFileSystem.h"
+
+#include <memory>
+
+namespace mlir {
+class MLIRContext;
+} // namespace mlir
+namespace cir {
+class CIRGenModule;
+
+class CIRGenerator : public clang::ASTConsumer {
+  virtual void anchor();
+  clang::DiagnosticsEngine &Diags;
+  clang::ASTContext *astCtx;
+  llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>
+      fs; // Only used for debug info.
+
+  const clang::CodeGenOptions codeGenOpts; // Intentionally copied in.
+
+  [[maybe_unused]] unsigned HandlingTopLevelDecls;
----------------
erichkeane wrote:

Probably better to bring this in only when used.

https://github.com/llvm/llvm-project/pull/91007