greenforce: Bump to 20221221 build

Clang version: 12.0.1
Binutils version: 2.34
LLVM repo commit: Revert "Revert "[Coverage] Fix branch coverage merging in FunctionCoverageSummary::get() for instantiation""
Link: llvm/llvm-project@fed41342a

Signed-off-by: greenforce-auto-build <[email protected]>
Change-Id: Ief527ae47bde7fc2ffbebc9d5b0e615d89c9d9c2

Author: greenforce-auto-build

.gitattributes

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+lib/libclang-cpp.so.12git filter=lfs diff=lfs merge=lfs -text

README.md

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+# Greenforce Clang
+
+## Host compatibility
+
+This toolchain is built on Ubuntu 20.04, which uses glibc 2.31. Compatibility with older distributions cannot be guaranteed. Other libc implementations (such as musl) are not supported.
+
+## Building Linux
+
+Make sure you have this toolchain in your `PATH`:
+
+```bash
+export PATH="$HOME/toolchains/clang-llvm/bin:$PATH"
+```
+
+For an AArch64 cross-compilation setup, you must set the following variables. Some of them can be environment variables, but some must be passed directly to `make` as a command-line argument. It is recommended to pass **all** of them as `make` arguments to avoid confusing errors:
+
+- `CC=clang` (must be passed directly to `make`)
+- `CROSS_COMPILE=aarch64-linux-gnu-`
+- If your kernel has a 32-bit vDSO: `CROSS_COMPILE_ARM32=arm-linux-gnueabi-`
+
+Optionally, you can also choose to use as many LLVM tools as possible to reduce reliance on binutils. All of these must be passed directly to `make`:
+
+- `AR=llvm-ar`
+- `NM=llvm-nm`
+- `OBJCOPY=llvm-objcopy`
+- `OBJDUMP=llvm-objdump`
+- `STRIP=llvm-strip`
+
+Note, however, that additional kernel patches may be required for these LLVM tools to work. It is also possible to replace the binutils linkers (`lf.bfd` and `ld.gold`) with `lld` and use Clang's integrated assembler for inline assembly in C code, but that will require many more kernel patches and it is currently impossible to use the integrated assembler for *all* assembly code in the kernel.
+
+Android kernels older than 4.14 will require patches for compiling with any Clang toolchain to work; those patches are out of the scope of this project. See [android-kernel-clang](https://github.com/nathanchance/android-kernel-clang) for more information.
+
+Android kernels 4.19 and newer use the upstream variable `CROSS_COMPILE_COMPAT`. When building these kernels, replace `CROSS_COMPILE_ARM32` in your commands and scripts with `CROSS_COMPILE_COMPAT`.
+
+### Differences from other toolchains
+
+Greenforce Clang has been designed to be easy-to-use compared to other toolchains, such as [AOSP Clang](https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/). The differences are as follows:
+
+- `CLANG_TRIPLE` does not need to be set because we don't use AOSP binutils.
+- `LD_LIBRARY_PATH` does not need to be set because we set library load paths in the toolchain.
+- No separate GCC/binutils toolchains are necessary; all tools are bundled.
+
+#### Additional patches
+
+To use full Clang LTO with Greenforce Clang, you have to cherry-pick [ANDROID: generate_initcall_order.pl: Use two dash long options for llvm-nm](https://android.googlesource.com/kernel/common.git/+/240f2f8f42f57b46788379e0072836cb2cb40c8c) otherwise your kernel will not boot.