Add LLVM build workflow

Author: oitel

.github/workflows/build-llvm.yml

@@ -0,0 +1,81 @@
+name: Build LLVM
+
+on:
+  workflow_dispatch:
+    inputs:
+      llvm-version:
+        required: true
+        type: string
+
+jobs:
+  create-release:
+    runs-on: ubuntu-slim
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+
+      - name: Create release
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          gh release create "llvm-${{ inputs.llvm-version }}" \
+            --draft \
+            --title "LLVM ${{ inputs.llvm-version }}"
+
+  build-linux:
+    needs:
+      - create-release
+    runs-on: ${{ matrix.runner }}
+    container:
+      image: almalinux:8
+    strategy:
+      fail-fast: false
+      matrix:
+        arch: [x64, arm64]
+        include:
+          - arch: x64
+            runner: ubuntu-24.04
+          - arch: arm64
+            runner: ubuntu-24.04-arm
+
+    steps:
+      - name: Install tools
+        run: |
+          dnf install -y epel-release
+          dnf install -y --enablerepo powertools \
+            gcc-toolset-14 cmake ninja-build \
+            $(: CI requirements ) \
+            git \
+            $(: LLVM build requirements ) \
+            python3 xz
+
+      - name: Checkout
+        uses: actions/checkout@v6
+
+      - name: Download LLVM
+        run: |
+          ci/download_llvm.sh "${{ inputs.llvm-version }}"
+
+      - name: Build libclang
+        run: |
+          source /opt/rh/gcc-toolset-14/enable
+          ci/build_llvm.sh
+
+      - name: Create package
+        run: |
+          dnf install -y zip
+          mv llvm-out llvm
+          zip -r llvm-linux-$(uname -m).zip llvm/
+
+      - name: Upload package
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          # TODO: use a ready-made universal GitHub action
+          dnf config-manager --add-repo https://cli.github.com/packages/rpm/gh-cli.repo
+          dnf install -y gh
+          # fix git permissions
+          export HOME=${RUNNER_TEMP}
+          git config --global --add safe.directory '*'
+          # upload package
+          gh release upload "llvm-${{ inputs.llvm-version }}" llvm-linux-$(uname -m).zip --clobber