Changelog r23

Changelog

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

Announcements

• GNU binutils, excluding the GNU Assembler (GAS), has been removed. GAS will be removed in the next release. If you are building with -fno-integrated-as, file bugs if anything is preventing you from removing that flag. See Clang Migration Notes for advice about making assembly compatible with LLVM.

• Support for GDB has ended. GDB will be removed in the next release. Use LLDB instead. Note that ndk-gdb uses LLDB by default.

• NDK r23 is the last release that will support non-Neon. Beginning with NDK r24, the armeabi-v7a libraries in the sysroot will be built with Neon. A very small number of very old devices do not support Neon so most apps will not notice aside from the performance improvement.

• Jelly Bean (APIs 16, 17, and 18) will not be supported in the next NDK release. The minimum OS supported by the NDK for r24 will be KitKat (API level 19).

r23c

• Update LLVM to clang-r416183c2, based on LLVM 12 development.
  • Issue 1590: Fixed LLDB crashes when calling help on unknown commands.
  • Issue 1608: Fixed crash in vector conversions.
  • Issue 1619: Fixed performance regression in arm64 vectorization.
  • Issue 1645: Fixed crash caused by openmp master/critical pragmas.
  • Issue 1672: Fixed armeabi-v7a libunwind.a to be compatible with vfpv3-d16 (remember that this is the last release that will support that FPU setting).
• Issue 1410: Fix ndk-build for Apple M1.
• Issue 1546: Universal binaries (M1 support) for make (affects ndk-build).
• Issue 1577: Universal binaries (M1 support) for shader-tools (vulkan compilers).
• Issue 1569: Fix -fno-integrated-as for Linux and Darwin hosts by making GAS symlink relative
• Issue 1589: Fix incorrect API level check for -Wl,--no-rosegment in ndk-build and CMake.
• Issue 1593: Improved ndk-which to fall back to LLVM tools when the GNU names are used. For example, ndk-which strip will now return the path to llvm-strip instead of nothing.
• Issue 1610: Fix ANDROID_NATIVE_API_LEVEL CMake variable when using the non-legacy toolchain file.
• Issue 1618: Fix behavior of ANDROID_CPP_FEATURES with the new toolchain file.
• Issue 1656: The new CMake toolchain file now ignores ANDROID_ARM_MODE when it is passed for ABIs other than armeabi-v7a like the legacy toolchain file did. With CMake 3.22 it is an error to set CMAKE_ANDROID_ARM_MODE for other ABIs, so this fixes a potential incompatibility between the legacy and new toolchains when using CMake 3.22+.
• Issue 1693: The NDK's toolchain file for CMake (android.toolchain.cmake) defaults to the legacy toolchain file for all versions of CMake. The new toolchain file can still be enabled using -DANDROID_USE_LEGACY_TOOLCHAIN_FILE=OFF.

r23b

• Update LLVM to clang-r416183c1, based on LLVM 12 development.
  • Issue 1540: Fixed compiler crash when using coroutines.
  • Issue 1544: Now uses universal binaries for M1 Macs.
  • Issue 1551: Prevent each translation unit from receiving its own copy of emulated thread-local global variables.
  • Issue 1555: Fixed compiler crash for armeabi-v7a.
• Issue 1492: ndk-build.cmd: Stop using make's -O (--output-sync) flag on Windows to avoid fcntl(): Bad file descriptor error.
• Issue 1553: Updated sysroot to latest Android 12.
• Issue 1569: Fixed -fno-integrated-as not being able to find the assembler.
• CMake changes:
  • Issue 1536: Make optimization flags used with CMake more consistent. Historically thumb release builds used -Oz, but AGP switched to using RelWithDebInfo for release builds in the latest release which was not using -Oz. To reduce per-arch differences and behavior differences compared to CMake's defaults, -Oz use was removed. You may see code size increases for armeabi-v7a due to this, but also increased optimization. To restore the prior behavior, add -Oz to your cflags.
  • Issue 1560: Fixed pull-up of unsupported API levels when using the new CMake toolchain file. This affects CMake 3.21 and ANDROID_USE_LEGACY_TOOLCHAIN_FILE=ON use cases, and was the common case for AGP users with a minSdkVersion below 21.
  • Issue 1573: Fixed ANDROID_USE_LEGACY_TOOLCHAIN_FILE not being obeyed during CMake try-compile.
  • Issue 1581: Added workaround for CMake Issue 22647, which was causing MINGW to be incorrectly defined by CMake when building for Android on a Windows host. This only affected those using the Android toolchain file when CMake 3.21 or newer was used. This likely was not a regression for users not using the Android toolchain. The change will fix both use cases.

Changes

• Includes Android 12 APIs.
• Updated LLVM to clang-r416183b, based on LLVM 12 development.
  • Issue 1047: Fixes crash when using ASan with the CFI unwinder.
  • Issue 1096: Includes support for Polly. Enable by adding -mllvm -polly to your cflags.
  • Issue 1230: LLVM's libunwind is now used instead of libgcc for all architectures rather than just 32-bit Arm.
  • Issue 1231: LLVM's libclang_rt.builtins is now used instead of libgcc.
  • Issue 1406: Fixes crash with Neon intrinsic.
• Vulkan validation layer source and binaries are no longer shipped in the NDK. The latest are now posted directly to GitHub.
• Vulkan tools source is also removed, specifically vulkan_wrapper. It should be downloaded upstream from GitHub.
• The toolchain file (android.toolchain.cmake) is refactored to base on CMake's integrated Android support. This new toolchain file will be enabled by default for CMake 3.21 and newer. No user side change is expected. But if anything goes wrong, please file a bug and set ANDROID_USE_LEGACY_TOOLCHAIN_FILE=ON to restore the legacy behavior.
  • When using the new behavior (when using CMake 3.21+ and not explicitly selecting the legacy toolchain), default build flags may change. One of the primary goals was to reduce the behavior differences between our toolchain and CMake, and CMake's default flags do not always match the legacy toolchain file. Most notably, if using CMAKE_BUILD_TYPE=Release, your optimization type will likely be -O3 instead of -O2 or -Oz. See Issue 1536 for more information.
• Issue 929: find_library now prefers shared libraries from the sysroot over static libraries.
• Issue 1390: ndk-build now warns when building a static executable with the wrong API level.
• Issue 1452: NDK_ANALYZE=1 now sets APP_CLANG_TIDY=true rather than using scan-build. clang-tidy performs all the same checks by default, and scan-build was no longer working. See the bug for more details, but no user-side changes should be needed.

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.