README.md - toolchain/llvm_android - Git at Google

 ## Android Clang/LLVM Toolchain


 > Quick links:
 > * [Android clang build instructions](https://android.googlesource.com/toolchain/llvm_android/+/mirror-goog-main-llvm-toolchain-source/BUILD.md)
 > * [Android clang version history](https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/+/mirror-goog-main-llvm-toolchain-source/README.md)

 Android's clang toolchain is used to build the Android platform, kernel and is also part of the Android NDK.  It also builds various tools and projects in the Android ecosystem.  See [this](https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/+/refs/heads/mirror-goog-main-llvm-toolchain-source/README.md) page for a list of current versions used by various projects.

 Android clang follows a rolling release schedule based on upstream llvm-project's main branch.  It **does not** correspond to a numbered llvm-project release branch.


 ### Clang Version

 Each clang prebuilt directory has a `clang_source_info.md` (starting with clang-r428724) that mentions the llvm-project commit from which this version is branched.  It also lists cherry-picks from upstream LLVM and downstream changes needed to qualify this prebuilt for the various Android use cases.


 ### Update Schedule

 At any point of time, there is an in-progress attempt to release a new clang.  Due to the complexity of the Android code base and breaking changes from llvm-project, there is no guaranteed schedule or cadence in clang updates.

 In practice, there have been an average of 3-4 updates a year (rougly new clang every 3-4 months) for the past several years.

 > Subscribe to https://groups.google.com/g/android-llvm to get notified when a clang version is planned and when it is released.


 ### Android Clang Development

 Android clang development happens in the `main-llvm-toolchain` branch in googleplex-android.  See [here](https://android.googlesource.com/toolchain/llvm_android/+/mirror-goog-main-llvm-toolchain-source/BUILD.md) for build instructions.

 [git_main-llvm-toolchain](https://go/ab/git_main-llvm-toolchain) is the internal CI build of Android clang toolchain.

 clang binaries from this CI branch are checked into three platform-specific projects:

 *   [prebuilts/clang/host/linux-x86](https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/+/refs/heads/mirror-goog-main-llvm-toolchain-source)
 *   [prebuilts/clang/host/darwin-x86](https://android.googlesource.com/platform/prebuilts/clang/host/darwin-x86/+/refs/heads/mirror-goog-main-llvm-toolchain-source)
 *   [prebuilts/clang/host/windows-x86](https://android.googlesource.com/platform/prebuilts/clang/host/windows-x86/+/refs/heads/mirror-goog-main-llvm-toolchain-source)
	## Android Clang/LLVM Toolchain


	> Quick links:
	> * [Android clang build instructions](https://android.googlesource.com/toolchain/llvm_android/+/mirror-goog-main-llvm-toolchain-source/BUILD.md)
	> * [Android clang version history](https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/+/mirror-goog-main-llvm-toolchain-source/README.md)

	Android's clang toolchain is used to build the Android platform, kernel and is also part of the Android NDK. It also builds various tools and projects in the Android ecosystem. See [this](https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/+/refs/heads/mirror-goog-main-llvm-toolchain-source/README.md) page for a list of current versions used by various projects.

	Android clang follows a rolling release schedule based on upstream llvm-project's main branch. It does not correspond to a numbered llvm-project release branch.


	### Clang Version

	Each clang prebuilt directory has a `clang_source_info.md` (starting with clang-r428724) that mentions the llvm-project commit from which this version is branched. It also lists cherry-picks from upstream LLVM and downstream changes needed to qualify this prebuilt for the various Android use cases.


	### Update Schedule

	At any point of time, there is an in-progress attempt to release a new clang. Due to the complexity of the Android code base and breaking changes from llvm-project, there is no guaranteed schedule or cadence in clang updates.

	In practice, there have been an average of 3-4 updates a year (rougly new clang every 3-4 months) for the past several years.

	> Subscribe to https://groups.google.com/g/android-llvm to get notified when a clang version is planned and when it is released.


	### Android Clang Development

	Android clang development happens in the `main-llvm-toolchain` branch in googleplex-android. See [here](https://android.googlesource.com/toolchain/llvm_android/+/mirror-goog-main-llvm-toolchain-source/BUILD.md) for build instructions.

	[git_main-llvm-toolchain](https://go/ab/git_main-llvm-toolchain) is the internal CI build of Android clang toolchain.

	clang binaries from this CI branch are checked into three platform-specific projects:

	* [prebuilts/clang/host/linux-x86](https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/+/refs/heads/mirror-goog-main-llvm-toolchain-source)
	* [prebuilts/clang/host/darwin-x86](https://android.googlesource.com/platform/prebuilts/clang/host/darwin-x86/+/refs/heads/mirror-goog-main-llvm-toolchain-source)
	* [prebuilts/clang/host/windows-x86](https://android.googlesource.com/platform/prebuilts/clang/host/windows-x86/+/refs/heads/mirror-goog-main-llvm-toolchain-source)