[llvm] 71e97ad - Only define LLVM_EXTERNAL_VISIBILITY when building libLLVM dylib

[Ben Langmuir via llvm-commits]

Author: Ben Langmuir
Date: 2021-12-14T09:59:07-08:00
New Revision: 71e97ad35b2abcc89cc8ff471a3eb404120cf208

URL: https://github.com/llvm/llvm-project/commit/71e97ad35b2abcc89cc8ff471a3eb404120cf208
DIFF: https://github.com/llvm/llvm-project/commit/71e97ad35b2abcc89cc8ff471a3eb404120cf208.diff

LOG: Only define LLVM_EXTERNAL_VISIBILITY when building libLLVM dylib

When building LLVM static libraries, we should not make symbols more
visible than CMAKE_CXX_VISIBILITY_PRESET, since the goal may be to have
a purely hidden llvm embedded in another library. Instead, we only
define LLVM_EXTERNAL_VISIBILITY for the dynamic library build (when
LLVM_BUILD_LLVM_DYLIB=YES).

Differential Revision: https://reviews.llvm.org/D113610

Added: 
    

Modified: 
    llvm/include/llvm/Config/llvm-config.h.cmake
    llvm/include/llvm/Support/Compiler.h

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Config/llvm-config.h.cmake b/llvm/include/llvm/Config/llvm-config.h.cmake
index 4493bb65d4442..a182f835c0f26 100644
--- a/llvm/include/llvm/Config/llvm-config.h.cmake
+++ b/llvm/include/llvm/Config/llvm-config.h.cmake
@@ -103,4 +103,7 @@
 /* Define if the xar_open() function is supported on this platform. */
 #cmakedefine LLVM_HAVE_LIBXAR ${LLVM_HAVE_LIBXAR}
 
+/* Define if building libLLVM shared library */
+#cmakedefine LLVM_BUILD_LLVM_DYLIB
+
 #endif

diff  --git a/llvm/include/llvm/Support/Compiler.h b/llvm/include/llvm/Support/Compiler.h
index c5318137ed3d0..abb0dab16cbc1 100644
--- a/llvm/include/llvm/Support/Compiler.h
+++ b/llvm/include/llvm/Support/Compiler.h
@@ -121,12 +121,16 @@
 /// On PE/COFF targets, library visibility is the default, so this isn't needed.
 ///
 /// LLVM_EXTERNAL_VISIBILITY - classes, functions, and variables marked with
-/// this attribute will be made public and visible outside of any shared library
-/// they are linked in to.
+/// this attribute will be made public and visible outside the libLLVM dynamic
+/// library.
 #if __has_attribute(visibility) && !defined(__MINGW32__) &&                    \
     !defined(__CYGWIN__) && !defined(_WIN32)
 #define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden")))
-#define LLVM_EXTERNAL_VISIBILITY __attribute__ ((visibility("default")))
+#if defined(LLVM_BUILD_LLVM_DYLIB)
+#define LLVM_EXTERNAL_VISIBILITY __attribute__((visibility("default")))
+#else
+#define LLVM_EXTERNAL_VISIBILITY
+#endif
 #else
 #define LLVM_LIBRARY_VISIBILITY
 #define LLVM_EXTERNAL_VISIBILITY