[libc++abi][libunwind] Run c++abi and unwind tests against a fake install root (#110171)

This is what we started doing in libc++ and it straightens up a lot of
things that only happened to work before, notably the presence of
relative rpaths in dylibs when running from the build tree.

This unlocks the ability to link against a just-built dylib but run
against another version of the dylib (for example the system-provided
one), which is necessary for proper backdeployment testing.

This patch adds a lot of code duplication between the libc++ and
libc++abi testing setups. However, there is already a large amount of
duplication and the only real way to get rid of it is to merge libc++abi
into libc++. In a way, this patch is a step in that direction because it
closes the gap between the two libraries' testing setup.

libunwind/CMakeLists.txt

@@ -68,7 +68,11 @@ set(LIBUNWIND_LIBRARY_VERSION "1.0" CACHE STRING
    this also controls the linker's 'current_version' property.")
 
 if(MINGW)
-  set(LIBUNWIND_DEFAULT_TEST_CONFIG "llvm-libunwind-mingw.cfg.in")
+  if (LIBUNWIND_ENABLE_SHARED)
+    set(LIBUNWIND_DEFAULT_TEST_CONFIG "llvm-libunwind-shared-mingw.cfg.in")
+  else()
+    set(LIBUNWIND_DEFAULT_TEST_CONFIG "llvm-libunwind-static-mingw.cfg.in")
+  endif()
 elseif (LIBUNWIND_ENABLE_SHARED)
   set(LIBUNWIND_DEFAULT_TEST_CONFIG "llvm-libunwind-shared.cfg.in")
 else()

libunwind/test/CMakeLists.txt

@@ -8,6 +8,20 @@ macro(pythonize_bool var)
   endif()
 endmacro()
 
+set(LIBUNWIND_TESTING_INSTALL_PREFIX "${LIBUNWIND_BINARY_DIR}/test-suite-install")
+add_custom_target(libunwind-install-unwind-for-testing
+  DEPENDS unwind-headers
+          unwind
+  COMMAND ${CMAKE_COMMAND} -E make_directory "${LIBUNWIND_TESTING_INSTALL_PREFIX}"
+  COMMAND "${CMAKE_COMMAND}"
+          -DCMAKE_INSTALL_COMPONENT=unwind-headers
+          -DCMAKE_INSTALL_PREFIX="${LIBUNWIND_TESTING_INSTALL_PREFIX}"
+          -P "${CMAKE_BINARY_DIR}/cmake_install.cmake"
+  COMMAND "${CMAKE_COMMAND}"
+          -DCMAKE_INSTALL_COMPONENT=unwind
+          -DCMAKE_INSTALL_PREFIX="${LIBUNWIND_TESTING_INSTALL_PREFIX}"
+          -P "${CMAKE_BINARY_DIR}/cmake_install.cmake")
+
 pythonize_bool(LIBUNWIND_ENABLE_CET)
 pythonize_bool(LIBUNWIND_ENABLE_GCS)
 pythonize_bool(LIBUNWIND_ENABLE_THREADS)
@@ -48,4 +62,4 @@ configure_lit_site_cfg(
 
 add_lit_testsuite(check-unwind "Running libunwind tests"
   ${CMAKE_CURRENT_BINARY_DIR}
-  DEPENDS unwind)
+  DEPENDS libunwind-install-unwind-for-testing)

libunwind/test/configs/cmake-bridge.cfg.in

@@ -29,5 +29,6 @@ if not @LIBUNWIND_ENABLE_THREADS@:
     config.available_features.add('libunwind-no-threads')
 
 # Add substitutions for bootstrapping the test suite configuration
-config.substitutions.append(('%{include}', '@LIBUNWIND_SOURCE_DIR@/include'))
-config.substitutions.append(('%{lib}', '@LIBUNWIND_LIBRARY_DIR@'))
+config.substitutions.append(('%{install-prefix}', '@LIBUNWIND_TESTING_INSTALL_PREFIX@'))
+config.substitutions.append(('%{include}', '@LIBUNWIND_TESTING_INSTALL_PREFIX@/include'))
+config.substitutions.append(('%{lib}', '@LIBUNWIND_TESTING_INSTALL_PREFIX@/lib'))

libunwind/test/configs/llvm-libunwind-shared-mingw.cfg.in

@@ -0,0 +1,25 @@
+# This testing configuration handles running the test suite against LLVM's libunwind
+# using a DLL with MinGW/Clang on Windows.
+
+lit_config.load_config(config, '@CMAKE_CURRENT_BINARY_DIR@/cmake-bridge.cfg')
+
+config.substitutions.append(('%{flags}', ''))
+config.substitutions.append(('%{compile_flags}',
+    '-nostdinc++ -I %{include} -funwind-tables'
+))
+config.substitutions.append(('%{link_flags}',
+    '-L %{lib} -lunwind'
+))
+config.substitutions.append(('%{exec}',
+    '%{executor} --execdir %T --prepend_env PATH=%{install-prefix}/bin -- '
+))
+
+import os, site
+site.addsitedir(os.path.join('@LIBUNWIND_LIBCXX_PATH@', 'utils'))
+import libcxx.test.params, libcxx.test.config
+libcxx.test.config.configure(
+    libcxx.test.params.DEFAULT_PARAMETERS,
+    libcxx.test.features.DEFAULT_FEATURES,
+    config,
+    lit_config
+)

libunwind/test/configs/llvm-libunwind-static-mingw.cfg.in

@@ -1,5 +1,5 @@
 # This testing configuration handles running the test suite against LLVM's libunwind
-# using either a DLL or a static library, with MinGW/Clang on Windows.
+# using a static library with MinGW/Clang on Windows.
 
 lit_config.load_config(config, '@CMAKE_CURRENT_BINARY_DIR@/cmake-bridge.cfg')