[libcxxabi] Add support for building and testing the unwinder.

[danalbert]

Summary

Note: The unwinder currently only works on Darwin and on ARM Linux. Non-ARM Linux support is not yet implemented, and will fail to build.

[danalbert]

jroelofs: I know you had mentioned that the unwinder might be moving to compiler-rt. Any idea about timeline on that?

src/Unwind/CMakeLists.txt

88

Do we want it to just be libunwind? Could also build it in to libc++abi (or compiler-rt), but I assume we want it to be a different library.

[jroelofs]

(non-ARM Linux won't build by design).

Why?

src/Unwind/CMakeLists.txt

8

Sort them?

15

I'm very 'green' when it comes to cmake, but this looks odd. Should the language be set to some ASM thing instead of C?

29

Sort them?

What about:
include/libunwind.h
include/unwind.h
include/mach-o/compact_unwind_encoding.h

31

would this append_if be better if it lived just below the set for LIBUNWIND_SORUCES?

65

lib/buildit has a big list of EXTRA_FLAGS. Are those taken care of here?

EXTRA_FLAGS="-fstrict-aliasing -Wstrict-aliasing=2 \
  -Wsign-conversion -Wshadow -Wconversion -Wunused-variable \
  -Wmissing-field-initializers -Wchar-subscripts -Wmismatched-tags \
  -Wmissing-braces -Wshorten-64-to-32 -Wsign-compare \
  -Wstrict-aliasing=2 -Wstrict-overflow=4 -Wunused-parameter \
  -Wnewline-eof"

72

can this be something like "-install_name /usr/lib/lib${OUTPUT_NAME}.1.dylib" to avoid having to set that in multiple places?

test/lit.cfg

209

This changes the order of link_flags when not using llvm_unwinder. Is that okay?

[danalbert]

In D4448#6, @jroelofs wrote:

(non-ARM Linux won't build by design).

Why?

Because there is no support for it. It isn't actually my code that prevents it from building, but rather the check at src/Unwind/UnwindCursor.hpp:1278 which requires either _LIBUNWIND_SUPPORT_COMPACT_UNWIND, _LIBUNWIND_SUPPORT_DWARF_UNWIND, or LIBCXXABI_AM_EHABI. The config that was added with the EHABI change left the dwarf and compact defines set to 0 because neither is available yet (for Linux). I'm working on fixing this right now, but it will be a different patch.

src/Unwind/CMakeLists.txt

15

I had done that originally, but it didn't work when building in tree. I'm also pretty new to cmake, but I looked at compiler-rt and this is how they handle it.

29

I think I may have mistakenly added those to the cxxabi target rather than the unwinder... I'll fix that.

test/lit.cfg

209

I was wondering the same thing. I'll try to find more info.

[jroelofs]

Ah ok. Now I remember you mentioning this on #llvm.

src/Unwind/CMakeLists.txt

15

ok

[jroelofs]

Well, phabricator didn't quite do what I intended with that....

[danalbert]

src/Unwind/CMakeLists.txt

65

Fixed these in a separate patch since they should have been there regardless of this one. Committed as r212768.

[jroelofs]

src/Unwind/CMakeLists.txt

65

cool

[jroelofs]

LGTM

[danalbert]

Submitted as r212824.

CMakeLists.txt

 option(LIBCXXABI_ENABLE_ASSERTIONS "Enable assertions independent of build mode." ON)
 option(LIBCXXABI_ENABLE_PEDANTIC "Compile with pedantic enabled." ON)
 option(LIBCXXABI_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)
+option(LIBCXXABI_USE_LLVM_UNWINDER "Build and use the LLVM unwinder." OFF)
 
 # Default to building a shared library so that the default options still test
 # the libc++abi that is being built. There are two problems with testing a

 # soname, etc...
 add_subdirectory(src)
 
+if (LIBCXXABI_USE_LLVM_UNWINDER)
+  add_subdirectory(src/Unwind)
+endif()
+
 if(NOT LIBCXXABI_ENABLE_SHARED)
   # TODO: Fix the libc++ cmake files so that libc++abi can be statically linked.
   # As it is now, libc++ will prefer linking against a dynamic libc++abi in the

src/Unwind/CMakeLists.txt

+# Get sources
+set(LIBUNWIND_SOURCES
+  libunwind.cpp
+  UnwindLevel1.c
+  Unwind-EHABI.cpp
+  Unwind-sjlj.c
+  UnwindLevel1-gcc-ext.c
+)
+
+set(LIBUNWIND_ASM_SOURCES
+  UnwindRegistersSave.S
+  UnwindRegistersRestore.S
+)
+
+set_source_files_properties(${LIBUNWIND_ASM_SOURCES} PROPERTIES LANGUAGE C)
+
+set(LIBUNWIND_HEADERS
+  AddressSpace.hpp
+  unwind_ext.h
+  DwarfParser.hpp
+  config.h
+  DwarfInstructions.hpp
+  dwarf2.h
+  UnwindCursor.hpp
+  CompactUnwinder.hpp
+  assembly.h
+  Registers.hpp
+  libunwind_ext.h
+)
+
+append_if(LIBUNWIND_SOURCES APPLE Unwind_AppleExtras.cpp)
+
+# Add all the headers to the project for IDEs.
+if (MSVC_IDE)
+  # Force them all into the headers dir on MSVC, otherwise they end up at
+  # project scope because they don't have extensions.
+  source_group("Header Files" FILES ${LIBUNWIND_HEADERS})
+endif()
+
+if (LIBUNWIND_ENABLE_SHARED)
+  add_library(unwind SHARED
+    ${LIBUNWIND_SOURCES}
+    ${LIBUNWIND_ASM_SOURCES}
+    ${LIBUNWIND_HEADERS}
+    )
+else()
+  add_library(unwind STATIC
+    ${LIBUNWIND_SOURCES}
+    ${LIBUNWIND_ASM_SOURCES}
+    ${LIBUNWIND_HEADERS}
+    )
+endif()
+
+include_directories("${LIBCXXABI_LIBCXX_INCLUDES}")
+
+# Generate library list.
+set(libraries ${LIBCXXABI_CXX_ABI_LIBRARIES})
+append_if(libraries LIBCXXABI_HAS_C_LIB c)
+
+target_link_libraries(unwind ${libraries})
+
+# Setup flags.
+append_if(compile_flags LIBCXXABI_HAS_FPIC_FLAG -fPIC)
+append_if(link_flags LIBCXXABI_HAS_NODEFAULTLIBS_FLAG -nodefaultlibs)
+
+if ( APPLE )
+  if ( CMAKE_OSX_DEPLOYMENT_TARGET STREQUAL "10.6" )
+    list(APPEND compile_flags "-U__STRICT_ANSI__")
+    list(APPEND link_flags
+      "-compatibility_version 1"
+      "-current_version ${LIBCXXABI_VERSION}"
+      "-install_name /usr/lib/libllvmunwind.1.dylib"
+      "/usr/lib/libSystem.B.dylib")
+  else()
+    list(APPEND link_flags
+      "-compatibility_version 1"
+      "-install_name /usr/lib/libllvmunwind.1.dylib")
+  endif()
+endif()
+
+string(REPLACE ";" " " compile_flags "${compile_flags}")
+string(REPLACE ";" " " link_flags "${link_flags}")
+
+set_target_properties(unwind
+  PROPERTIES
+    COMPILE_FLAGS "${compile_flags}"
+    LINK_FLAGS    "${link_flags}"
+    OUTPUT_NAME   "llvmunwind"
+    VERSION       "1.0"
+    SOVERSION     "1"
+  )
+
+install(TARGETS unwind
+  LIBRARY DESTINATION lib
+  ARCHIVE DESTINATION lib
+  )

test/CMakeLists.txt

 set(LIBCXXABI_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/..)
 set(LIBCXXABI_BINARY_DIR ${CMAKE_BINARY_DIR})
 pythonize_bool(LIBCXXABI_ENABLE_SHARED)
+pythonize_bool(LIBCXXABI_USE_LLVM_UNWINDER)
 
 set(AUTO_GEN_COMMENT "## Autogenerated by libcxxabi configuration.\n# Do not edit!")
 configure_file(

   list(APPEND LIBCXXABI_TEST_DEPS cxx)
 endif()
 
+if (LIBCXXABI_USE_LLVM_UNWINDER)
+  list(APPEND LIBCXXABI_TEST_DEPS unwind)
+endif()
+
 add_lit_testsuite(check-libcxxabi "Running libcxxabi tests"
   ${CMAKE_CURRENT_BINARY_DIR}
   DEPENDS ${LIBCXXABI_TEST_DEPS}

test/lit.cfg

     if enable_shared is None:
         lit_config.fatal("enable_shared must be defined")
 
+llvm_unwinder = getattr(config, 'llvm_unwinder', None)
+if llvm_unwinder is None:
+    lit_config.fatal("llvm_unwinder must be defined")
+
 link_flags = []
 link_flags_str = lit_config.params.get('link_flags', None)
 if link_flags_str is None:

         if sys.platform == 'darwin':
             link_flags += ['-lSystem']
         elif sys.platform == 'linux2':
-            link_flags += ['-lgcc_eh', '-lc', '-lm', '-lpthread', '-lgcc_s']
+            link_flags += ['-lc', '-lm', '-lpthread']
+            if llvm_unwinder:
+                link_flags += ['-lllvmunwind', '-ldl']
+            else:
+                link_flags += ['-lgcc_eh', '-lgcc_s']
         else:
             lit_config.fatal("unrecognized system")
 

test/lit.site.cfg.in

 config.python_executable     = "@PYTHON_EXECUTABLE@"
 config.enable_shared         = @LIBCXXABI_ENABLE_SHARED@
 config.libcxx_includes       = "@LIBCXXABI_LIBCXX_INCLUDES@"
+config.llvm_unwinder         = @LIBCXXABI_USE_LLVM_UNWINDER@
 
 # Let the main config do the real work.
 lit_config.load_config(config, "@LIBCXXABI_SOURCE_DIR@/test/lit.cfg")