[clang] [CIR] Enable PCH Build- (PR #222201)

[Erich Keane via cfe-commits]

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@@ -0,0 +1,23 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// Precompiled header for clangCIR. Uses private headers.
+///
+//===----------------------------------------------------------------------===//
+
+#include "Address.h"
+#include "CIRGenBuilder.h"
+#include "CIRGenCXXABI.h"
+#include "CIRGenFunction.h"
+#include "CIRGenModule.h"
+#include "CIRGenValue.h"
+#include "mlir/Dialect/OpenACC/OpenACC.h"
+#include "mlir/Dialect/OpenMP/OpenMPDialect.h"
+#include "mlir/Dialect/Ptr/IR/MemorySpaceInterfaces.h"
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erichkeane wrote:

A bit of claude-analysis: it determined that ~1/4 of our TUs pull in either OpenACC or OpenMP, and both are quite large, so are worth it?

The MemorySpaceInterfaces.h is redundant (Address.h brings it in), so I can remove that if you think it it is reasonable.

https://github.com/llvm/llvm-project/pull/222201