[PATCH] D60750: [libc++][CMake] Clean up logic for choosing which unwinder lib to link with tests

[Tom Stellard via Phabricator via llvm-commits]

tstellar created this revision.
tstellar added reviewers: mstorsjo, ldionne, phosek.
Herald added subscribers: libcxx-commits, dexonsmith, christof, mgorny.
Herald added a reviewer: EricWF.
Herald added a project: libc++.

The main functional change in this patch is that when
LIBCXXABI_USE_LLVM_UNWINDER and LIBCXX_ENABLE_ABI_LINKER_SCRIPT are both
enabled, -lgcc_s and -lgcc will no longer be added to the linker flags
for the test suite.

In this case, linking against libgcc is unnecessary, because the linker
script adds -lunwind.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D60750

Files:
  libcxx/test/CMakeLists.txt
  libcxx/test/lit.site.cfg.in
  libcxx/utils/libcxx/test/target_info.py


Index: libcxx/utils/libcxx/test/target_info.py
===================================================================
--- libcxx/utils/libcxx/test/target_info.py
+++ libcxx/utils/libcxx/test/target_info.py
@@ -233,19 +233,25 @@
         enable_threads = ('libcpp-has-no-threads' not in
                           self.full_config.config.available_features)
         llvm_unwinder = self.full_config.get_lit_bool('llvm_unwinder', False)
+        libcxx_is_linker_script  = self.full_config.get_lit_bool('libcxx_is_linker_script', False)
         shared_libcxx = self.full_config.get_lit_bool('enable_shared', True)
         flags += ['-lm']
-        if not llvm_unwinder:
-            flags += ['-lgcc_s', '-lgcc']
         if enable_threads:
             flags += ['-lpthread']
             if not shared_libcxx:
                 flags += ['-lrt']
         flags += ['-lc']
-        if llvm_unwinder:
+        if llvm_unwinder and not libcxx_is_linker_script:
+            # FIXME: Why does llvm unwinder need -ldl?
             flags += ['-lunwind', '-ldl']
-        else:
-            flags += ['-lgcc_s']
+        elif not llvm_unwinder:
+            # If we aren't using llvm unwinder, then fallback to using libgcc's
+            # unwind implementation.
+            # FIXME: Why is -lgcc needed for the unwinder?
+            flags += ['-lgcc_s', '-lgcc']
+        # If we are using a linker script and llvm_unwinder is eanbled, then we
+        # don't need to explicitly link against -lunwind, since the linker
+        # script will take care of that for us.
         builtins_lib = self.full_config.get_lit_conf('builtins_library')
         if builtins_lib:
             flags += [builtins_lib]
Index: libcxx/test/lit.site.cfg.in
===================================================================
--- libcxx/test/lit.site.cfg.in
+++ libcxx/test/lit.site.cfg.in
@@ -27,6 +27,7 @@
 
 config.executor                 = "@LIBCXX_EXECUTOR@"
 config.llvm_unwinder            = @LIBCXXABI_USE_LLVM_UNWINDER@
+config.libcxx_is_linker_script  = @LIBCXX_ENABLE_ABI_LINKER_SCRIPT@
 config.builtins_library         = "@LIBCXX_BUILTINS_LIBRARY@"
 config.has_libatomic            = @LIBCXX_HAS_ATOMIC_LIB@
 config.use_libatomic            = @LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB@
Index: libcxx/test/CMakeLists.txt
===================================================================
--- libcxx/test/CMakeLists.txt
+++ libcxx/test/CMakeLists.txt
@@ -20,12 +20,6 @@
   set(LIBCXX_CXX_ABI_LIBNAME "none")
 endif()
 
-# The tests shouldn't link to libunwind if we have a linker script which
-# already does so.
-if (LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
-  set(LIBCXXABI_USE_LLVM_UNWINDER OFF)
-endif()
-
 pythonize_bool(LIBCXX_ENABLE_EXCEPTIONS)
 pythonize_bool(LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY)
 pythonize_bool(LIBCXX_ENABLE_RTTI)
@@ -35,6 +29,7 @@
 pythonize_bool(LIBCXX_GENERATE_COVERAGE)
 pythonize_bool(LIBCXXABI_ENABLE_SHARED)
 pythonize_bool(LIBCXXABI_USE_LLVM_UNWINDER)
+pythonize_bool(LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
 pythonize_bool(LIBCXX_USE_COMPILER_RT)
 pythonize_bool(LIBCXX_HAS_ATOMIC_LIB)
 pythonize_bool(LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB)


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