[PATCH] D57107: [libunwind] Support building hermetic static library

[Petr Hosek via Phabricator]

phosek created this revision.
phosek added reviewers: ldionne, echristo.
Herald added subscribers: libcxx-commits, christof, mgorny.

This is useful when the static libunwind library is being linked into
shared libraries that may be used in with other shared libraries that
use different unwinder. We want to avoid avoid exporting libunwind
symbols in those cases. This achieved by a new CMake option which can be
enabled by libunwind vendors as needed.

The same CMake option has already been added to libc++ and libc++abi in
D55404 <https://reviews.llvm.org/D55404> and D56026 <https://reviews.llvm.org/D56026>.


Repository:
  rUNW libunwind

https://reviews.llvm.org/D57107

Files:
  libunwind/CMakeLists.txt
  libunwind/src/CMakeLists.txt


Index: libunwind/src/CMakeLists.txt
===================================================================
--- libunwind/src/CMakeLists.txt
+++ libunwind/src/CMakeLists.txt
@@ -105,17 +105,44 @@
 set_property(SOURCE ${LIBUNWIND_C_SOURCES}
              APPEND_STRING PROPERTY COMPILE_FLAGS " ${LIBUNWIND_C_FLAGS}")
 
+macro(unwind_object_library name)
+  cmake_parse_arguments(ARGS "" "" "DEFINES;FLAGS" ${ARGN})
+
 # Add a object library that contains the compiled source files.
-add_library(unwind_objects OBJECT ${LIBUNWIND_SOURCES} ${LIBUNWIND_HEADERS})
+  add_library(${name} OBJECT ${LIBUNWIND_SOURCES} ${LIBUNWIND_HEADERS})
+
+  if(ARGS_DEFINES)
+    target_compile_definitions(${name} PRIVATE ${ARGS_DEFINES})
+  endif()
+
+  set_target_properties(unwind_objects
+                        PROPERTIES
+                          COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}"
+                          POSITION_INDEPENDENT_CODE ON)
 
-set_target_properties(unwind_objects
-                      PROPERTIES
-                        COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}"
-                        POSITION_INDEPENDENT_CODE ON)
+  if(ARGS_FLAGS)
+    target_compile_options(${name} PRIVATE ${ARGS_FLAGS})
+  endif()
+endmacro()
+
+if(LIBUNWIND_HERMETIC_STATIC_LIBRARY)
+  append_flags_if_supported(UNWIND_STATIC_OBJECTS_FLAGS -fvisibility=hidden)
+  append_flags_if_supported(UNWIND_STATIC_OBJECTS_FLAGS -fvisibility-global-new-delete-hidden)
+  unwind_object_library(unwind_static_objects
+    DEFINES _LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS
+    FLAGS ${UNWIND_STATIC_OBJECTS_FLAGS})
+  unwind_object_library(unwind_shared_objects)
+  set(unwind_static_sources $<TARGET_OBJECTS:unwind_static_objects>)
+  set(unwind_shared_sources $<TARGET_OBJECTS:unwind_shared_objects>)
+else()
+  unwind_object_library(unwind_objects)
+  set(unwind_static_sources $<TARGET_OBJECTS:unwind_objects>)
+  set(unwind_shared_sources $<TARGET_OBJECTS:unwind_objects>)
+endif()
 
 # Build the shared library.
 if (LIBUNWIND_ENABLE_SHARED)
-  add_library(unwind_shared SHARED $<TARGET_OBJECTS:unwind_objects>)
+  add_library(unwind_shared SHARED ${unwind_shared_sources})
   if(COMMAND llvm_setup_rpath)
     llvm_setup_rpath(unwind_shared)
   endif()
@@ -134,7 +161,7 @@
 
 # Build the static library.
 if (LIBUNWIND_ENABLE_STATIC)
-  add_library(unwind_static STATIC $<TARGET_OBJECTS:unwind_objects>)
+  add_library(unwind_static STATIC ${unwind_static_sources})
   target_link_libraries(unwind_static ${libraries})
   set_target_properties(unwind_static
                         PROPERTIES
Index: libunwind/CMakeLists.txt
===================================================================
--- libunwind/CMakeLists.txt
+++ libunwind/CMakeLists.txt
@@ -168,6 +168,9 @@
   message(FATAL_ERROR "LIBUNWIND_BUILD_32_BITS=ON is not supported on this platform.")
 endif()
 
+option(LIBUNWIND_HERMETIC_STATIC_LIBRARY
+  "Do not export any symbols from the static library." OFF)
+
 #===============================================================================
 # Configure System
 #===============================================================================


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