[clang] [CIR] Upstream initial support for CIR flattening (PR #130648)

[Erich Keane via cfe-commits]

================
@@ -0,0 +1,77 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 implements lowering of CIR attributes and operations directly to
+// LLVMIR.
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
+#include "mlir/IR/DialectRegistry.h"
+#include "mlir/Target/LLVMIR/LLVMTranslationInterface.h"
+#include "mlir/Target/LLVMIR/ModuleTranslation.h"
+#include "clang/CIR/Dialect/IR/CIRAttrs.h"
+#include "clang/CIR/Dialect/IR/CIRDialect.h"
+#include "clang/CIR/MissingFeatures.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/IR/Constant.h"
+#include "llvm/IR/GlobalVariable.h"
+
+using namespace llvm;
+
+namespace cir {
+namespace direct {
+
+/// Implementation of the dialect interface that converts CIR attributes to LLVM
+/// IR metadata.
+class CIRDialectLLVMIRTranslationInterface
+    : public mlir::LLVMTranslationDialectInterface {
+public:
+  using LLVMTranslationDialectInterface::LLVMTranslationDialectInterface;
+#if 0
----------------
erichkeane wrote:

Oh?  Can we just remove this and add it when we need it?

https://github.com/llvm/llvm-project/pull/130648