[libcxx] Add code coverage configuration to CMake and LIT.

Summary:
This patch adds configuration to CMake and LIT for running the libc++ test-suite to generate code coverage.

To use code coverage use following instructions.

* Find the clang resource dir using `$CXX -print-search-dirs`. Let <library-dir> be the first library search directory.
* `cmake <regular-options> -DLIBCXX_GENERATE_COVERAGE=ON -DLIBCXX_COVERAGE_LIBRARY=<library-dir>/lib/<platform>/libclang_rt.profile.a <source>`
* `make cxx`
* `make check-libcxx`
* `make generate-libcxx-coverage`


The reason I want this patch upstreamed is so I can setup a bot that generates code coverage and posts in online for every revision. 



Reviewers: mclow.lists, jroelofs, danalbert

Reviewed By: danalbert

Differential Revision: http://reviews.llvm.org/D8716

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@233669 91177308-0d34-0410-b5e6-96231b3b80d8

test/CMakeLists.txt

@@ -47,6 +47,8 @@ if (LIT_EXECUTABLE)
   pythonize_bool(LIBCXX_ENABLE_STDOUT)
   pythonize_bool(LIBCXX_ENABLE_THREADS)
   pythonize_bool(LIBCXX_ENABLE_MONOTONIC_CLOCK)
+  pythonize_bool(LIBCXX_GENERATE_COVERAGE)
+
   # The tests shouldn't link to any ABI library when it has been linked into
   # libc++ statically.
   if (LIBCXX_ENABLE_STATIC_ABI_LIBRARY)
@@ -71,6 +73,14 @@ if (LIT_EXECUTABLE)
     DEPENDS cxx
     COMMENT "Running libcxx tests"
     ${cmake_3_2_USES_TERMINAL})
+
+  if (LIBCXX_GENERATE_COVERAGE)
+    include(CodeCoverage)
+    set(output_dir "${CMAKE_CURRENT_BINARY_DIR}/coverage")
+    set(capture_dirs "${LIBCXX_LIB_CMAKEFILES_DIR}/cxx.dir/;${CMAKE_CURRENT_BINARY_DIR}")
+    set(extract_dirs "${LIBCXX_SOURCE_DIR}/include;${LIBCXX_SOURCE_DIR}/src")
+    setup_lcov_test_target_coverage("cxx" "${output_dir}" "${capture_dirs}" "${extract_dirs}")
+  endif()
 else()
   message(WARNING
           "LIT_EXECUTABLE not set, no check-libcxx target will be available!")

test/libcxx/test/config.py

@@ -98,6 +98,7 @@ class Configuration(object):
         self.configure_debug_mode()
         self.configure_warnings()
         self.configure_sanitizer()
+        self.configure_coverage()
         self.configure_substitutions()
         self.configure_features()
 
@@ -594,6 +595,12 @@ class Configuration(object):
                 self.lit_config.fatal('unsupported value for '
                                       'use_sanitizer: {0}'.format(san))
 
+    def configure_coverage(self):
+        self.generate_coverage = self.get_lit_bool('generate_coverage', False)
+        if self.generate_coverage:
+            self.cxx.flags += ['-g', '--coverage']
+            self.cxx.compile_flags += ['-O0']
+
     def configure_substitutions(self):
         sub = self.config.substitutions
         # Configure compiler substitions

test/lit.site.cfg.in

@@ -20,6 +20,7 @@ config.configuration_variant    = "@LIBCXX_LIT_VARIANT@"
 config.target_triple            = "@LIBCXX_TARGET_TRIPLE@"
 config.sysroot                  = "@LIBCXX_SYSROOT@"
 config.gcc_toolchain            = "@LIBCXX_GCC_TOOLCHAIN@"
+config.generate_coverage        = "@LIBCXX_GENERATE_COVERAGE@"
 config.target_info              = "@LIBCXX_TARGET_INFO@"
 config.executor                 = "@LIBCXX_EXECUTOR@"