Don't use libandroid_support for modern API levels.ndk-r17-beta2ndk-r17-beta1ndk-r17

If we're targeting a new enough platform version, we don't actually
need to cover any gaps in libc for libc++ support. In those cases,
save size in the APK by avoiding libandroid_support.

This is also a requirement for static executables, since using
libandroid_support with a modern libc.a will result in multiple symbol
definition errors.

Test: ndk/checkbuild.py && ndk/run_tests.py
Bug: https://github.com/android-ndk/ndk/issues/272
Change-Id: I4cb76272dc7271a02cba46d3cc20a369a16ff39d
(cherry picked from commit db08a420b9b812321691180e97da1a3facc7391e)

2 files changed, 36 insertions, 21 deletions

diff --git a/Android.mk b/Android.mk
index cfb43f2b1..11c161423 100644
--- a/Android.mk
+++ b/Android.mk
@@ -88,14 +88,18 @@ include $(CLEAR_VARS)
 LOCAL_MODULE := c++_static
 LOCAL_SRC_FILES := libs/$(TARGET_ARCH_ABI)/lib$(LOCAL_MODULE)$(TARGET_LIB_EXTENSION)
 LOCAL_EXPORT_C_INCLUDES := $(libcxx_export_includes)
-
-# This doesn't affect the prebuilt itself since this is a prebuilt library, but
-# the build system needs to know about the dependency so we can sort the
-# exported includes properly.
-LOCAL_STATIC_LIBRARIES := libc++abi libandroid_support
+LOCAL_STATIC_LIBRARIES := libc++abi
 LOCAL_EXPORT_CPPFLAGS := $(libcxx_export_cxxflags)
 LOCAL_EXPORT_LDFLAGS := $(libcxx_export_ldflags)
-LOCAL_EXPORT_STATIC_LIBRARIES := libc++abi libandroid_support
+LOCAL_EXPORT_STATIC_LIBRARIES := libc++abi
+
+ifeq ($(NDK_PLATFORM_NEEDS_ANDROID_SUPPORT),true)
+    # This doesn't affect the prebuilt itself since this is a prebuilt library,
+    # but the build system needs to know about the dependency so we can sort the
+    # exported includes properly.
+    LOCAL_STATIC_LIBRARIES += libandroid_support
+    LOCAL_EXPORT_STATIC_LIBRARIES += libandroid_support
+endif
 
 # We use the LLVM unwinder for 32-bit ARM.
 ifeq ($(TARGET_ARCH_ABI),armeabi-v7a)
@@ -110,13 +114,16 @@ LOCAL_EXPORT_C_INCLUDES := \
     $(libcxx_export_includes) \
     $(libcxxabi_c_includes) \
 
-# This doesn't affect the prebuilt itself since this is a prebuilt library, but
-# the build system needs to know about the dependency so we can sort the
-# exported includes properly.
-LOCAL_STATIC_LIBRARIES := libandroid_support
 LOCAL_EXPORT_CPPFLAGS := $(libcxx_export_cxxflags)
 LOCAL_EXPORT_LDFLAGS := $(libcxx_export_ldflags)
-LOCAL_EXPORT_STATIC_LIBRARIES := libandroid_support
+
+ifeq ($(NDK_PLATFORM_NEEDS_ANDROID_SUPPORT),true)
+    # This doesn't affect the prebuilt itself since this is a prebuilt library,
+    # but the build system needs to know about the dependency so we can sort the
+    # exported includes properly.
+    LOCAL_STATIC_LIBRARIES := libandroid_support
+    LOCAL_EXPORT_STATIC_LIBRARIES := libandroid_support
+endif
 
 # We use the LLVM unwinder for 32-bit ARM.
 ifeq ($(TARGET_ARCH_ABI),armeabi-v7a)
@@ -124,7 +131,7 @@ ifeq ($(TARGET_ARCH_ABI),armeabi-v7a)
 endif
 include $(PREBUILT_SHARED_LIBRARY)
 
-ifneq (,$(filter armeabi%,$(TARGET_ARCH_ABI)))
+ifeq ($(TARGET_ARCH_ABI),armeabi-v7a)
 # We define this module here rather than in a separate cxx-stl/libunwind because
 # we don't actually want to make the API available (yet).
 include $(CLEAR_VARS)
@@ -150,10 +157,14 @@ LOCAL_CPP_FEATURES := rtti exceptions
 LOCAL_EXPORT_C_INCLUDES := $(libcxx_export_includes)
 LOCAL_EXPORT_CPPFLAGS := $(libcxx_export_cxxflags)
 LOCAL_EXPORT_LDFLAGS := $(libcxx_export_ldflags)
-LOCAL_STATIC_LIBRARIES := libc++abi android_support
+LOCAL_STATIC_LIBRARIES := libc++abi
+
+ifeq ($(NDK_PLATFORM_NEEDS_ANDROID_SUPPORT),true)
+    LOCAL_STATIC_LIBRARIES += android_support
+endif
 
 # We use the LLVM unwinder for all the 32-bit ARM targets.
-ifneq (,$(filter armeabi%,$(TARGET_ARCH_ABI)))
+ifeq ($(TARGET_ARCH_ABI),armeabi-v7a)
     LOCAL_STATIC_LIBRARIES += libunwind
     LOCAL_EXPORT_STATIC_LIBRARIES += libunwind
 endif
@@ -166,7 +177,9 @@ LOCAL_WHOLE_STATIC_LIBRARIES := c++_static libc++abi
 LOCAL_EXPORT_C_INCLUDES := $(libcxx_export_includes)
 LOCAL_EXPORT_CPPFLAGS := $(libcxx_export_cxxflags)
 LOCAL_EXPORT_LDFLAGS := $(libcxx_export_ldflags)
-LOCAL_STATIC_LIBRARIES := android_support
+ifeq ($(NDK_PLATFORM_NEEDS_ANDROID_SUPPORT),true)
+    LOCAL_STATIC_LIBRARIES := android_support
+endif
 LOCAL_LDFLAGS := $(libcxx_ldflags)
 # Use --as-needed to strip the DT_NEEDED on libstdc++.so (bionic's) that the
 # driver always links for C++ but we don't use.
diff --git a/utils/libcxx/ndk/test/config.py b/utils/libcxx/ndk/test/config.py
index 3e4bb8535..7b351bfae 100644
--- a/utils/libcxx/ndk/test/config.py
+++ b/utils/libcxx/ndk/test/config.py
@@ -56,7 +56,7 @@ class Configuration(libcxx.test.config.Configuration):
         super(Configuration, self).configure_compile_flags()
 
         arch = self.get_lit_conf('arch')
-        api = self.get_lit_conf('api')
+        api = int(self.get_lit_conf('api'))
 
         sysroot = os.path.join(os.environ['NDK'], 'sysroot')
         self.cxx.compile_flags.extend(['--sysroot', sysroot])
@@ -77,15 +77,16 @@ class Configuration(libcxx.test.config.Configuration):
                 '-mthumb',
             ])
 
-        android_support_headers = os.path.join(
-            os.environ['NDK'], 'sources/android/support/include')
-        self.cxx.compile_flags.append('-I' + android_support_headers)
+        if api < 21:
+            android_support_headers = os.path.join(
+                os.environ['NDK'], 'sources/android/support/include')
+            self.cxx.compile_flags.append('-I' + android_support_headers)
 
     def configure_link_flags(self):
         self.cxx.link_flags.append('-nodefaultlibs')
 
         arch = self.get_lit_conf('arch')
-        api = self.get_lit_conf('api')
+        api = int(self.get_lit_conf('api'))
 
         sysroot_path = 'platforms/android-{}/arch-{}'.format(api, arch)
         platform_sysroot = os.path.join(os.environ['NDK'], sysroot_path)
@@ -100,7 +101,8 @@ class Configuration(libcxx.test.config.Configuration):
         self.cxx.link_flags.append('-gcc-toolchain')
         self.cxx.link_flags.append(gcc_toolchain)
 
-        self.cxx.link_flags.append('-landroid_support')
+        if api < 21:
+            self.cxx.link_flags.append('-landroid_support')
         triple = self.get_lit_conf('target_triple')
         if triple.startswith('arm-') or triple.startswith('armv7-'):
             self.cxx.link_flags.append('-lunwind')