ci/android: add a script to build LLVM libraries for Android

In order to build the mesa llvmpipe driver for Android, LLVM libraries
for Android are needed, but building them each time a new upstream mesa
is built would be too much overhead.

So add a script to build LLVM libraries for Android and call it from the
debian/android_build job. The actual build will be performed only when
necessary and the resulting artifact will be uploaded to the S3 bucket
to be re-used when building mesa for Android.

The build process follows what has been documented in
docs/drivers/llvmpipe.rst

Reviewed-by: Guilherme Gallo <guilherme.gallo@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31093>

.gitlab-ci.yml

@@ -72,6 +72,8 @@ variables:
       echo -n '${S3_JWT}' > '${S3_JWT_FILE}' &&
       unset CI_JOB_JWT S3_JWT  # Unsetting vulnerable env variables
   S3_HOST: s3.freedesktop.org
+  # This bucket is used to fetch ANDROID prebuilts and images
+  S3_ANDROID_BUCKET: mesa-rootfs
   # This bucket is used to fetch the kernel image
   S3_KERNEL_BUCKET: mesa-rootfs
   # Bucket for git cache

.gitlab-ci/container/build-android-x86_64-llvm.sh

@@ -0,0 +1,110 @@
+#!/usr/bin/env bash
+
+set -exu
+
+# If CI vars are not set, assign an empty value, this prevents -u to fail
+: "${CI:=}"
+: "${CI_PROJECT_PATH:=}"
+
+# Early check for required env variables, relies on `set -u`
+: "$ANDROID_SDK_VERSION"
+: "$ANDROID_NDK"
+: "$LLVM_VERSION"
+: "$LLVM_ARTIFACT_NAME"
+: "$S3_JWT_FILE"
+: "$S3_HOST"
+: "$S3_ANDROID_BUCKET"
+
+# Check if the auth file used later on for CI is non-empty
+if [ -n "$CI" ] && [ ! -s "${S3_JWT_FILE}" ]; then
+  echo "Error: ${S3_JWT_FILE} is empty." 1>&2
+  exit 1
+fi
+
+if curl -s -o /dev/null -I -L -f --retry 4 --retry-delay 15 "https://${S3_HOST}/${S3_ANDROID_BUCKET}/${CI_PROJECT_PATH}/${LLVM_ARTIFACT_NAME}.tar.zst"; then
+  echo "Artifact ${LLVM_ARTIFACT_NAME}.tar.zst already exists, skip re-building."
+  exit
+fi
+
+# Install some dependencies needed to build LLVM
+EPHEMERAL=(
+  ninja-build
+  unzip
+)
+
+apt-get update
+apt-get install -y --no-install-recommends --no-remove "${EPHEMERAL[@]}"
+
+ANDROID_NDK_ROOT="/${ANDROID_NDK}"
+if [ ! -d "$ANDROID_NDK_ROOT" ];
+then
+  curl -L --retry 4 -f --retry-all-errors --retry-delay 60 \
+    -o "${ANDROID_NDK}.zip" \
+    "https://dl.google.com/android/repository/${ANDROID_NDK}-linux.zip"
+  unzip -d / "${ANDROID_NDK}.zip" "$ANDROID_NDK/source.properties" "$ANDROID_NDK/build/cmake/*" "$ANDROID_NDK/toolchains/llvm/*"
+  rm "${ANDROID_NDK}.zip"
+fi
+
+if [ ! -d "/llvm-project" ];
+then
+  mkdir "/llvm-project"
+  pushd "/llvm-project"
+  git init
+  git remote add origin https://github.com/llvm/llvm-project.git
+  git fetch --depth 1 origin "$LLVM_VERSION"
+  git checkout FETCH_HEAD
+  popd
+fi
+
+pushd "/llvm-project"
+
+# Checkout again the intended version, just in case of a pre-existing full clone
+git checkout "$LLVM_VERSION" || true
+
+LLVM_INSTALL_PREFIX="/${LLVM_ARTIFACT_NAME}"
+
+rm -rf build/
+cmake -GNinja -S llvm -B build/ \
+    -DCMAKE_TOOLCHAIN_FILE="${ANDROID_NDK_ROOT}/build/cmake/android.toolchain.cmake" \
+    -DANDROID_ABI=x86_64 \
+    -DANDROID_PLATFORM="android-${ANDROID_SDK_VERSION}" \
+    -DANDROID_NDK="${ANDROID_NDK_ROOT}" \
+    -DCMAKE_ANDROID_ARCH_ABI=x86_64 \
+    -DCMAKE_ANDROID_NDK="${ANDROID_NDK_ROOT}" \
+    -DCMAKE_BUILD_TYPE=MinSizeRel \
+    -DCMAKE_SYSTEM_NAME=Android \
+    -DCMAKE_SYSTEM_VERSION="${ANDROID_SDK_VERSION}" \
+    -DCMAKE_INSTALL_PREFIX="${LLVM_INSTALL_PREFIX}" \
+    -DCMAKE_CXX_FLAGS="-march=x86-64 --target=x86_64-linux-android${ANDROID_SDK_VERSION} -fno-rtti" \
+    -DLLVM_HOST_TRIPLE="x86_64-linux-android${ANDROID_SDK_VERSION}" \
+    -DLLVM_TARGETS_TO_BUILD=X86 \
+    -DLLVM_BUILD_LLVM_DYLIB=OFF \
+    -DLLVM_BUILD_TESTS=OFF \
+    -DLLVM_BUILD_EXAMPLES=OFF \
+    -DLLVM_BUILD_DOCS=OFF \
+    -DLLVM_BUILD_TOOLS=OFF \
+    -DLLVM_ENABLE_RTTI=OFF \
+    -DLLVM_BUILD_INSTRUMENTED_COVERAGE=OFF \
+    -DLLVM_NATIVE_TOOL_DIR="${ANDROID_NDK_ROOT}/toolchains/llvm/prebuilt/linux-x86_64/bin" \
+    -DLLVM_ENABLE_PIC=False \
+    -DLLVM_OPTIMIZED_TABLEGEN=ON
+
+ninja "-j${FDO_CI_CONCURRENT:-4}" -C build/ install
+
+popd
+
+rm -rf /llvm-project
+
+tar --zstd -cf "${LLVM_ARTIFACT_NAME}.tar.zst" "$LLVM_INSTALL_PREFIX"
+
+# If run in CI upload the tar.zst archive to S3 to avoid rebuilding it if the
+# version does not change, and delete it.
+# The file is not deleted for non-CI because it can be useful in local runs.
+if [ -n "$CI" ]; then
+  ci-fairy s3cp --token-file "${S3_JWT_FILE}" "${LLVM_ARTIFACT_NAME}.tar.zst" "https://${S3_HOST}/${S3_ANDROID_BUCKET}/${CI_PROJECT_PATH}/${LLVM_ARTIFACT_NAME}.tar.zst"
+  rm "${LLVM_ARTIFACT_NAME}.tar.zst"
+fi
+
+rm -rf "$LLVM_INSTALL_PREFIX"
+
+apt-get purge -y "${EPHEMERAL[@]}"

.gitlab-ci/container/debian/android_build.sh

@@ -23,7 +23,7 @@ apt-get install -y --no-remove "${EPHEMERAL[@]}"
 ndk=$ANDROID_NDK
 curl -L --retry 4 -f --retry-all-errors --retry-delay 60 \
   -o $ndk.zip https://dl.google.com/android/repository/$ndk-linux.zip
-unzip -d / $ndk.zip "$ndk/toolchains/llvm/*"
+unzip -d / $ndk.zip "$ndk/source.properties" "$ndk/build/cmake/*" "$ndk/toolchains/llvm/*"
 rm $ndk.zip
 # Since it was packed as a zip file, symlinks/hardlinks got turned into
 # duplicate files.  Turn them into hardlinks to save on container space.
@@ -100,4 +100,9 @@ done
 cd ..
 rm -rf $LIBELF_VERSION
 
+
+# Build LLVM libraries for Android only if necessary, uploading a copy to S3
+# to avoid rebuilding it in a future run if the version does not change.
+bash .gitlab-ci/container/build-android-x86_64-llvm.sh
+
 apt-get purge -y "${EPHEMERAL[@]}"

.gitlab-ci/container/gitlab-ci.yml

@@ -161,6 +161,8 @@ debian/android_build:
     MESA_IMAGE_TAG: &debian-android_build ${DEBIAN_BUILD_TAG}
     ANDROID_SDK_VERSION: 33
     ANDROID_NDK: android-ndk-r25b
+    LLVM_VERSION: llvmorg-18.1.8
+    LLVM_ARTIFACT_NAME: android-x86_64-llvm-20241219
 
 .use-debian/android_build:
   extends:

.gitlab-ci/image-tags.yml

@@ -16,7 +16,7 @@ variables:
    DEBIAN_BASE_TAG: "20241125-crosvm"
 
    DEBIAN_X86_64_BUILD_IMAGE_PATH: "debian/x86_64_build"
-   DEBIAN_BUILD_TAG: "20241122-sections"
+   DEBIAN_BUILD_TAG: "20241219-android"
 
    DEBIAN_X86_64_TEST_BASE_IMAGE: "debian/x86_64_test-base"
    DEBIAN_ARM64_TEST_BASE_IMAGE: "debian/arm64_test-base"