[libcxxabi] Introduce an externally threaded libc++abi variant.

r281179 Introduced an externally threaded variant of the libc++ library. This
patch adds support for a similar library variant for libc++abi.

Differential revision: https://reviews.llvm.org/D27575

Reviewers: EricWF

git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@290888 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 29 insertions, 0 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index dbb3602..f51f402 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -118,6 +118,9 @@ option(LIBCXXABI_USE_LLVM_UNWINDER "Build and use the LLVM unwinder." OFF)
 option(LIBCXXABI_USE_COMPILER_RT "Use compiler-rt instead of libgcc" OFF)
 option(LIBCXXABI_ENABLE_THREADS "Build with threads enabled" ON)
 option(LIBCXXABI_HAS_PTHREAD_API "Ignore auto-detection and force use of pthread API" OFF)
+option(LIBCXXABI_HAS_EXTERNAL_THREAD_API
+  "Build libc++abi with an externalized threading API.
+  This option may only be set to ON when LIBCXXABI_ENABLE_THREADS=ON." OFF)
 option(LIBCXXABI_BUILD_32_BITS "Build 32 bit libc++abi." ${LLVM_BUILD_32_BITS})
 set(LIBCXXABI_TARGET_TRIPLE "" CACHE STRING "Target triple for cross compiling.")
 set(LIBCXXABI_GCC_TOOLCHAIN "" CACHE PATH "GCC toolchain for cross compiling.")
@@ -347,20 +350,46 @@ if (NOT LIBCXXABI_ENABLE_SHARED)
   list(APPEND LIBCXXABI_COMPILE_FLAGS -D_LIBCPP_BUILD_STATIC)
 endif()
 
+# Threading
 if (NOT LIBCXXABI_ENABLE_THREADS)
   if (LIBCXXABI_HAS_PTHREAD_API)
     message(FATAL_ERROR "LIBCXXABI_HAS_PTHREAD_API can only"
                         " be set to ON when LIBCXXABI_ENABLE_THREADS"
                         " is also set to ON.")
   endif()
+  if (LIBCXXABI_HAS_EXTERNAL_THREAD_API)
+    message(FATAL_ERROR "LIBCXXABI_HAS_EXTERNAL_THREAD_API can only"
+                        " be set to ON when LIBCXXABI_ENABLE_THREADS"
+                        " is also set to ON.")
+  endif()
   add_definitions(-D_LIBCXXABI_HAS_NO_THREADS)
 endif()
 
+if (LIBCXXABI_HAS_PTHREAD_API AND LIBCXXABI_HAS_EXTERNAL_THREAD_API)
+  message(FATAL_ERROR "The options LIBCXXABI_HAS_EXTERNAL_THREAD_API"
+                      "and LIBCXXABI_HAS_PTHREAD_API cannot be both"
+                      "set to ON at the same time.")
+endif()
+
+if (LIBCXXABI_HAS_EXTERNAL_THREAD_API AND LIBCXXABI_ENABLE_SHARED)
+  # Need to allow unresolved symbols if this is to work with shared library builds
+  if (APPLE)
+    add_link_flags("-undefined dynamic_lookup")
+  else()
+    # Relax this restriction from HandleLLVMOptions
+    string(REPLACE "-Wl,-z,defs" "" CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS}")
+  endif()
+endif()
+
 if (LIBCXXABI_HAS_PTHREAD_API)
   add_definitions(-D_LIBCPP_HAS_THREAD_API_PTHREAD)
   add_definitions(-D_LIBCXXABI_USE_THREAD_API_PTHREAD)
 endif()
 
+if (LIBCXXABI_HAS_EXTERNAL_THREAD_API)
+  add_definitions(-D_LIBCXXABI_HAS_THREAD_API_EXTERNAL)
+endif()
+
 if (MSVC)
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
 endif()