Changelog r22

Changelog

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For Android Studio issues, follow the docs on the Android Studio site.

Announcements

• GNU binutils is deprecated and will be removed in an upcoming NDK release. Note that the GNU assembler (as) is a part of this. If you are building with -fno-integrated-as, file bugs if anything is preventing you from removing that flag. If you're using as directly, use clang instead.

• LLD is now the default linker. ndk-build and our CMake toolchain file have also migrated to using llvm-ar and llvm-strip.

  See the Changes section below for more information.

r22b

• Issue 1377: Fix Clang backend crash in register scavenging.
• Issue 1388: Fixed LLVM's incorrect conversion to list files for long command lines on Windows.
• Issue 1391: Fixed missing symbols from libz.a.
• Issue 1427: Fixed Clang auto-detection for CMake 3.19 and older for Windows.

Changes

• Updated LLVM to r399163b, based on LLVM 11 development.

  • Issue 829: Fixed issue with __attribute__((visibility("hidden"))) symbols sometimes not being hidden.
  • Issue 1149: Fixed Clang crash with #pragma detect_mismatch.
  • Issue 1212: Fixed llvm-strip to match GNU behavior for removing file symbols.
  • Issue 1248: Fixed LLD Neon crash.
  • Issue 1303: Fixed Neon intrinsic optimizer crash.

• Updated make to 4.3.

• Updated libc++, libc++abi, and libunwind to https://github.com/llvm/llvm-project/commit/52ec983895436089c5be0b0c4d967423db16045b.

• Issue 609: std::filesystem support is now included. There are two known issues:

  • Issue 1258: std::filesystem::perm_options::nofollow may not be honored on old devices.
  • Issue 1260: std::filesystem::canonical will incorrectly succeed when passed a non-existent path on old devices.

• Issue 843: llvm-strip is now used instead of strip to avoid breaking RelRO with LLD. Note that the Android Gradle Plugin performs its own stripping, so most users will need to upgrade to Android Gradle Plugin version 4.0 or newer to get the fix.

• Issue 1130: Fixed undefined references to new that could occur when building for APIs prior to 21 and the static libc++. Note that LLD appears to have been unaffected, but the problem is still present for ndk-build when using the deprecated linkers.

• Issue 1139: native_app_glue now hooks up the APP_CMD_WINDOW_RESIZED, APP_CMD_WINDOW_REDRAW_NEEDED, and APP_CMD_CONTENT_RECT_CHANGED messages.

• Issue 1196: Backtraces for crashes on devices older than API 29 are now correct when using LLD if using ndk-build or the CMake toolchain file. If using a different system and targeting devices older than API 29, use -Wl,--no-rosegment when linking. See the Build System Maintainers Guide for more information.

• The deprecated <NDK>/platforms and <NDK>/sysroot directories have been removed. These directories were merged and relocated into the toolchain during r19. The location of these contents should not be relevant to anyone, including build systems, since the toolchain handles them implicitly. If you are using a build system that hasn't adapted to the changes introduced in NDK r19, file a bug with your build system maintainer. See the Build System Maintainers Guide for information on using the NDK in your own build system.

• llvm-ar is now used instead of ar.

• Issue 1200: Fixed an issue with using dlclose with libraries using thread_local with non-trivial destructors and the static libc++.

• The legacy libc++ linker scripts in <NDK>/sources/cxx-stl/llvm-libc++ have been removed. The linkers scripts in the toolchain should be used instead as described by the Build System Maintainers Guide.

• LLD is now used by default. If your build is not yet compatible with LLD, you can continue using the deprecated linkers, set APP_LD=deprecated for ndk-build, ANDROID_LD=deprecated for CMake, or use an explicit -fuse-ld=gold or -fuse-ld=bfd in your custom build system. If you encounter issues be sure to file a bug, because this will not be an option in a subsequent release.

  Note that Issue 843 will affect builds using LLD with binutils strip and objcopy as opposed to llvm-strip and llvm-objcopy.

• ndk-gdb now uses lldb as the debugger. gdb is deprecated and will be removed in a future release. To fall back to gdb, use --no-lldb option. But please file a bug explaining why you couldn't use lldb.

Known Issues

• This is not intended to be a comprehensive list of all outstanding bugs.

• Issue 360: thread_local variables with non-trivial destructors will cause segfaults if the containing library is dlcloseed on devices running M or newer, or devices before M when using a static STL. The simple workaround is to not call dlclose.

• Issue 906: Clang does not pass -march=armv7-a to the assembler when using -fno-integrated-as. This results in the assembler generating ARMv5 instructions. Note that by default Clang uses the integrated assembler which does not have this problem. To workaround this issue, explicitly use -march=armv7-a when building for 32-bit ARM with the non-integrated assembler, or use the integrated assembler. ndk-build and CMake already contain these workarounds.

• Issue 988: Exception handling when using ASan via wrap.sh can crash. To workaround this issue when using libc++_shared, ensure that your application's libc++_shared.so is in LD_PRELOAD in your wrap.sh as in the following example:

  #!/system/bin/sh
  HERE="$(cd "$(dirname "$0")" && pwd)"
  export ASAN_OPTIONS=log_to_syslog=false,allow_user_segv_handler=1
  ASAN_LIB=$(ls $HERE/libclang_rt.asan-*-android.so)
  if [ -f "$HERE/libc++_shared.so" ]; then
      # Workaround for https://github.com/android/ndk/issues/988.
      export LD_PRELOAD="$ASAN_LIB $HERE/libc++_shared.so"
  else
      export LD_PRELOAD="$ASAN_LIB"
  fi
  "$@"

  There is no known workaround for libc++_static.

  Note that because this is a platform bug rather than an NDK bug this workaround will be necessary for this use case to work on all devices until at least Android R.

• Issue 1130: When using c++_static and the deprecated linker with ndk-build with an APP_PLATFORM below 21, undefined references to operator new may occur. The fix is to use LLD.

• This version of the NDK is incompatible with the Android Gradle plugin version 3.0 or older. If you see an error like No toolchains found in the NDK toolchains folder for ABI with prefix: mips64el-linux-android, update your project file to use plugin version 3.1 or newer. You will also need to upgrade to Android Studio 3.1 or newer.

• Issue 843: Using LLD with binutils strip or objcopy breaks RelRO. Use llvm-strip and llvm-objcopy instead. This issue has been resolved in Android Gradle Plugin version 4.0 (for non-Gradle users, the fix is also in ndk-build and our CMake toolchain file), but may affect other build systems.