[llvm] DLLExport InitLLVM

[andrurogerz]

Overview

Annotate the llvm::InitLLVM class so it is explicitly included in LLVM's public interface. When building LLVM as a Windows DLL, this annotation exports InitLLVM's public methods from the DLL.

Background

This change is required as part of the overall project to build LLVM as a Windows DLL described in #109483. Without this change, LLVM tools fail to link.

Validation

Built LLVM with MSVC on Windows 11:

cmake -B build -S llvm -G Ninja -DCMAKE_BUILD_TYPE=Debug -DLLVM_ENABLE_PROJECTS="clang" -DLLVM_OPTIMIZED_TABLEGEN -DLLVM_BUILD_LLVM_DYLIB=ON -DLLVM_BUILD_LLVM_DYLIB_VIS=ON -DLLVM_LINK_LLVM_DYLIB=ON -DCLANG_LINK_CLANG_DYLIB=ON
ninja -C build llvm-rc llvm-ar

Verified the annotated interface no longer appears in the list of unresolved external symbols.

[andrurogerz]

@compnerd, @vgvassilev

[llvmbot]

@llvm/pr-subscribers-llvm-support

Author: Andrew Rogers (andrurogerz)

Changes

Overview

Annotate the llvm::InitLLVM class so it is explicitly included in LLVM's public interface. When building LLVM as a Windows DLL, this annotation exports InitLLVM's public methods from the DLL.

Background

This change is required as part of the overall project to build LLVM as a Windows DLL described in #109483. Without this change, LLVM tools fail to link.

Validation

Built LLVM with MSVC on Windows 11:

cmake -B build -S llvm -G Ninja -DCMAKE_BUILD_TYPE=Debug -DLLVM_ENABLE_PROJECTS="clang" -DLLVM_OPTIMIZED_TABLEGEN -DLLVM_BUILD_LLVM_DYLIB=ON -DLLVM_BUILD_LLVM_DYLIB_VIS=ON -DLLVM_LINK_LLVM_DYLIB=ON -DCLANG_LINK_CLANG_DYLIB=ON
ninja -C build llvm-rc llvm-ar

Verified the annotated interface no longer appears in the list of unresolved external symbols.

---

Full diff: https://github.com/llvm/llvm-project/pull/127912.diff

1 Files Affected:

• (modified) llvm/include/llvm/Support/InitLLVM.h (+2-1)

diff --git a/llvm/include/llvm/Support/InitLLVM.h b/llvm/include/llvm/Support/InitLLVM.h
index 172d13bf21a55..68a7cc58a753a 100644
--- a/llvm/include/llvm/Support/InitLLVM.h
+++ b/llvm/include/llvm/Support/InitLLVM.h
@@ -11,6 +11,7 @@
 
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/Compiler.h"
 #include "llvm/Support/PrettyStackTrace.h"
 #include <optional>
 
@@ -32,7 +33,7 @@
 // InitLLVM calls llvm_shutdown() on destruction, which cleans up
 // ManagedStatic objects.
 namespace llvm {
-class InitLLVM {
+class LLVM_ABI InitLLVM {
 public:
   InitLLVM(int &Argc, const char **&Argv,
            bool InstallPipeSignalExitHandler = true);

[nikic]

Do not submit these one by one. Consolidating on the discussion in #127850.