Build LDC for Android

This page shows you how to build and run the standard library's tests using ldc on linux or Windows 10 (by using the new bash on linux subsystem), both as a command-line binary and as a GUI Android app. Prebuilt binaries of ldc are available here.

All of the standard library's unit tests and most of the compiler testsuite passes on Android/ARM.

Prerequisites

• linux/x64 shell, where you'll build and run ldc
  • You can use a virtual machine like VirtualBox/VMware, with at least 512 MB of memory and 1 GB of swap, particularly if building the phobos unit tests, and 10 GB of disk space.
  • Windows 10: You can alternately use Bash on Windows (the Windows Subsystem for Linux), see full steps below
• A pre-built D compiler for linux, as the ldc frontend is written in D.
  • You can get the official dmd release for linux or one of the ldc releases for linux. Many distros also have D compiler packages.
• Common development tools, such as CMake and ninja
• Android native toolchain, the NDK and optionally the SDK
  • The SDK is only needed if you want to package a GUI app; the NDK is enough if you just want to build a command-line binary, such as a test runner.
• Android/ARM, whether a device or emulator
  • The SDK comes with an emulator. I use actual hardware, so that's what I'll discuss.

Notes for Bash on Ubuntu on Windows

• Necessary packages

sudo apt-get install build-essential
sudo apt-get install git
sudo apt-get install cmake
sudo apt-get install unzip
sudo apt-get install libconfig-dev

• DMD Compiler

cd ~
curl -L -O http://downloads.dlang.org/releases/2.x/2.075.1/dmd_2.075.1-0_amd64.deb
sudo dpkg -i dmd_2.075.1-0_amd64.deb

• Android Native Development Kit

sudo mkdir -p /opt/android-sdk/ndk-bundle
curl -L -O https://dl.google.com/android/repository/android-ndk-r15c-linux-x86_64.zip
sudo unzip android-ndk-r15c-linux-x86_64.zip 'android-ndk-r15c/*' -d /opt/android-sdk/ndk-bundle
export NDK=/opt/android-sdk/ndk-bundle/android-ndk-r15c

As Windows Subsystem for Linux does not support USB, you have to install Android SDK and Ant on your Windows system and execute the commands "android" and "ant" from your DOS console.

Run the druntime and phobos unit tests

You can build the druntime and phobos unit tests and run the command-line test runner binaries on Android (don't add the -j5 flag to build in parallel unless you have gigabytes of memory available, as compiling some of the phobos modules' tests takes a fair amount of RAM):

make druntime-test-runner phobos2-test-runner

Copy the test runners to your device and run them. Assuming you have an SSH server set up on the computer where you're building with the linux shell and its IP address is 192.168.35.7, you can scp the binaries into the Termux Android app with these commands and run the tests:

apt install openssh
scp jo@192.168.35.7:"/path/to/your/ldc/build/runtime/{druntime,phobos2}-test-runner" .
./druntime-test-runner
./phobos2-testrunner

The tests take about 25 seconds to run on my quad-core tablet: all should pass. One module, core.sync.semaphore, will fail for any Android older than 6.0, because sem_destroy used to work differently in bionic. You can also run the tests for specified modules by passing their names to the test runner:

./druntime-test-runner core.thread core.sync.semaphore
./phobos2-testrunner std.datetime std.random

Run the druntime and phobos unit tests in an apk

You can also run the tests as part of a GUI app, ie an apk, which is a slightly different runtime environment. First, you can try cross-compiling a sample GUI app from the NDK that has been translated from C to D, as shown here. That simple OpenGLES 1.0 GUI app can be modified to run all the tests, which is what we'll do next. Clone my Android repo, if you haven't already, go to the native-activity sample app, and create the output directory the SDK expects:

cd ../../
git clone https://github.com/joakim-noah/android.git

cd android/samples/native-activity/
mkdir -p libs/armeabi-v7a/

Download and apply a small patch to have the sample app invoke the test runner and a patch for the test runner in druntime, then build the tests into a shared library this time:

curl -O https://gist.githubusercontent.com/joakim-noah/8ba3cd4958266f357295/raw/a52fcf1e63715f8b1bd3527afaa85872087b0f30/native_ldc_arm
git apply native_ldc_arm

cd ../../../ldc/runtime/druntime/
curl -O https://gist.githubusercontent.com/joakim-noah/348edc378d47fb90e32708be19286a2e/raw/2b473ff45ff4abc68852ebb1868354b8528026e0/druntime_1.3_ldc_arm
git apply druntime_1.3_ldc_arm

cd ../../build/
make test-runner-apk

This assumes that the ldc and android repositories are in the same directory, as shown in these instructions. If not, modify ANDROID_DIR in the CMake build script to use the path you want.

Finally, package the test runner apk:

cd ../../android/samples/native-activity/
export SDK=/path/to/your/android-sdk-linux
$SDK/tools/android update project -p . -s --target 1
ant debug

Transfer the resulting bin/NativeActivity-debug.apk to your device and install it. Also, copy the list of modules to test to the /sdcard/ directory. The app will append its results to /sdcard/test.log, so if you happen to have a file with that name, move it.

The app should show a black screen for about a minute, while all the tests run. A touch after that and it should start flashing a bunch of colors. If not, look at the output in /sdcard/test.log and check if the app hung after any particular tested module. You can remove that module from test.list and try running again.