0580563299
## Purpose This patch is one in a series of code-mods that annotate LLVM’s public interface for export. This patch annotates the `llvm-c` interface with a new `LLVM_C_ABI` annotation, which behaves like the `LLVM_ABI`. This annotation currently has no meaningful impact on the LLVM build; however, it is a prerequisite to support an LLVM Windows DLL (shared library) build. ## Overview 1. Add a new `llvm-c/Visibility.h` header file that defines a new `LLVM_C_ABI` macro. The macro resolves to the proper DLL export/import annotation on Windows and a "default" visibility annotation elsewhere. 2. Add a new `LLVM_ENABLE_LLVM_C_EXPORT_ANNOTATIONS` `#cmakedefine` that is used to gate the definition of `LLVM_C_ABI`. 3. Remove the existing `LLVM_C_ABI` definition from `llvm/Support/Compiler.h`. Update the small number of `LLVM_C_ABI` references to get it from the new `llvm-c/Visibility.h` header. 4. Code-mod annotate the public `llvm-c` interface using the [Interface Definition Scanner (IDS)](https://github.com/compnerd/ids) tool. 5. Format the changes with `clang-format`. ## Background This effort is tracked in #109483. Additional context is provided in [this discourse](https://discourse.llvm.org/t/psa-annotating-llvm-public-interface/85307), and documentation for `LLVM_ABI` and related annotations is found in the LLVM repo [here](https://github.com/llvm/llvm-project/blob/main/llvm/docs/InterfaceExportAnnotations.rst). ## Validation Local builds and tests to validate cross-platform compatibility. This included llvm, clang, and lldb on the following configurations: - Windows with MSVC - Windows with Clang - Linux with GCC - Linux with Clang - Darwin with Clang
45 lines
2.0 KiB
C++
45 lines
2.0 KiB
C++
/*===-- llvm-c/Visibility.h - Visibility macros for llvm-c ------*- C++ -*-===*\
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|* *|
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|* Part of the LLVM Project, under the Apache License v2.0 with LLVM *|
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|* Exceptions. *|
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|* See https://llvm.org/LICENSE.txt for license information. *|
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|* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception *|
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|* *|
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|*===----------------------------------------------------------------------===*|
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|* *|
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|* This header defines visibility macros used for the LLVM C interface. These *|
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|* macros are used to annotate C functions that should be exported as part of *|
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|* a shared library or DLL. *|
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|* *|
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\*===----------------------------------------------------------------------===*/
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#ifndef LLVM_C_VISIBILITY_H
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#define LLVM_C_VISIBILITY_H
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#include "llvm/Config/llvm-config.h"
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/// LLVM_C_ABI is the export/visibility macro used to mark symbols declared in
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/// llvm-c as exported when built as a shared library.
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#if !defined(LLVM_ABI_GENERATING_ANNOTATIONS)
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// TODO(https://github.com/llvm/llvm-project/issues/145406): eliminate need for
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// two preprocessor definitions to gate LLVM_ABI macro definitions.
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#if defined(LLVM_ENABLE_LLVM_C_EXPORT_ANNOTATIONS) && \
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!defined(LLVM_BUILD_STATIC)
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#if defined(_WIN32) && !defined(__MINGW32__)
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#if defined(LLVM_EXPORTS)
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#define LLVM_C_ABI __declspec(dllexport)
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#else
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#define LLVM_C_ABI __declspec(dllimport)
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#endif
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#elif defined(__has_attribute) && __has_attribute(visibility)
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#define LLVM_C_ABI __attribute__((visibility("default")))
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#endif
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#endif
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#if !defined(LLVM_C_ABI)
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#define LLVM_C_ABI
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#endif
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#endif
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#endif
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