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

[Aaron Ballman via cfe-commits]

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@@ -0,0 +1,46 @@
+//===--- CIRGenerator.cpp - Emit CIR from ASTs ----------------------------===//
+//
+// 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 builds an AST and converts it to CIR.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CIRGenModule.h"
+
+#include "clang/AST/DeclGroup.h"
+#include "clang/CIR/CIRGenerator.h"
+
+using namespace cir;
+using namespace clang;
+
+void CIRGenerator::anchor() {}
+
+CIRGenerator::CIRGenerator(clang::DiagnosticsEngine &diags,
+                           llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> vfs,
+                           const CodeGenOptions &CGO)
+    : Diags(diags), fs(std::move(vfs)), codeGenOpts{CGO},
+      HandlingTopLevelDecls(0) {}
+CIRGenerator::~CIRGenerator() {}
+
+void CIRGenerator::Initialize(ASTContext &astCtx) {
+  using namespace llvm;
+
+  this->astCtx = &astCtx;
+
+  CGM = std::make_unique<CIRGenModule>(*mlirCtx.get(), astCtx, codeGenOpts,
+                                       Diags);
+}
+
+bool CIRGenerator::HandleTopLevelDecl(DeclGroupRef D) {
+
+  for (DeclGroupRef::iterator I = D.begin(), E = D.end(); I != E; ++I) {
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AaronBallman wrote:

`llvm::for_each`? range-based for loop?

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