1# Building modified LLVM library from source
2
3## Sources
4
5Sources are available at [gitee](https://gitee.com/openharmony/third_party_llvm-project)
6
7## Build script
8
9The [script](build_llvm.sh) does not take command line arguments, instead build parameters should be set using environment variables.
10
11Some variables are mandatory, others are optional.
12
13### Environment variables list
14
15```bash
16### Required variables
17BUILD_DIR=<directory where building process takes place>
18LLVM_SOURCES=<directory with sources>/llvm
19VERSION=<version string, which is included in build/install directory names>(default: "main")
20PACKAGE_VERSION=<kit version>(default: $VERSION) # must match REQUIRED_LLVM_VERSION in libllvmbackend/CMakeLists.txt
21
22### Select targets to build, at least one must be set to "true"
23BUILD_X86_DEBUG=<debug version for x86_64 architecure>(default: false)
24BUILD_X86_RELEASE=<release version for x86_64 architecure>(default: false)
25BUILD_AARCH64_DEBUG=<debug version for arm64 architecure>(default: false)
26BUILD_AARCH64_RELEASE=<release version for arm64 architecure>(default: false)
27BUILD_OHOS_RELEASE=<release version for OHOS platform (OHOS SDK build)>(default: false)
28BUILD_OHOS_RELEASE_GN=<release version for OHOS GN platform (GN build)>(default: false)
29
30### Optional variables
31INSTALL_DIR=<directory for installation, empty means "do not install"> (default: "")
32
33DO_STRIPPING=<when install, strip libraries before installation>(default: true)
34DO_TAR=<when install, also pack llvm-$VERSION-*-*.tar.xz archives for corresponding folders>(default: true)
35
36OHOS_SDK=<path to native OHOS SDK>, required for any OHOS build.
37
38OHOS_PREBUILTS=<path to OHOS pre-build directory>, required for OHOS GN build.
39
40### Build tools
41CC=<C compiler> (default: "/usr/bin/clang-14")
42CXX=<C++ compiler> (default: "/usr/bin/clang++-14")
43STRIP=<strip utility> (default: "/usr/bin/llvm-strip-14")
44OPTIMIZE_DEBUG=<compile debug version with -O2>(default: true)
45```
46
47**Note! `PACKAGE_VERSION` must be properly set during build to match string
48constant `REQUIRED_LLVM_VERSION` from `libllvmbackend/CMakeLists.txt`.**
49
50## Example for local user build
51
52```bash
53cd /home/user/src
54git clone https://gitee.com/openharmony/third_party_llvm-project.git
55
56INSTALL_DIR="/home/user/inst" \
57BUILD_DIR="/home/user/build" \
58LLVM_SOURCES="/home/user/src/llvm-for-ark/llvm" \
59VERSION="15.0.4-ark99-beta9" \
60PACKAGE_VERSION="15.0.4-ark99" \
61OPTIMIZE_DEBUG=false \
62BUILD_X86_DEBUG=true \
63BUILD_AARCH64_DEBUG=true \
64bash -x ./build_llvm.sh
65```
66
67In this example, only `x86_64` and `arm64` debug versions are built. Then, they can be specified for Ark build, like:
68* host build: `-DLLVM_TARGET_PATH=/home/user/build/llvm-15.0.4-ark99-beta9-debug-x86_64`
69* cross-arm64 build:
70   * `-DLLVM_TARGET_PATH=/home/user/build/llvm-15.0.4-ark99-beta9-debug-aarch64`
71   * `-DLLVM_HOST_PATH=/home/user/build/llvm-15.0.4-ark99-beta9-debug-x86_64`
72
73## Example with packaging all necessary versions
74
75```bash
76INSTALL_DIR="/mnt/scratch/install" \
77BUILD_DIR="/mnt/scratch/build" \
78LLVM_SOURCES="/mnt/scratch/src/llvm-for-ark/llvm" \
79VERSION="15.0.4-ark99-beta9" \
80PACKAGE_VERSION="15.0.4-ark99" \
81OHOS_SDK="/opt/ohos-sdk/native" \
82OHOS_PREBUILTS="/home/user/ohos/prebuilts" \
83BUILD_X86_DEBUG=true \
84BUILD_X86_RELEASE=true \
85BUILD_AARCH64_DEBUG=true \
86BUILD_AARCH64_RELEASE=true \
87BUILD_OHOS_RELEASE=true \
88BUILD_OHOS_RELEASE_GN=true \
89bash -x ./build_llvm.sh
90```
91