bazel: custom llvm installation

Added ability to use custom LLVM installation

Signed-off-by: Michał Maślanka <[email protected]>

.bazelrc

@@ -25,6 +25,8 @@ common --registry=https://bcr.bazel.build
 build:libc++ --cxxopt=-stdlib=libc++
 build:libc++ --linkopt -lc++
 
+build:llvm --config=libc++
+
 # =================================
 # Sanitizer
 # =================================
@@ -36,6 +38,8 @@ build:sanitizer --copt -O1
 
 build:sanitizer-libc++ --config=sanitizer
 build:sanitizer-libc++ --config=libc++
+
+build:sanitizer-llvm --config=sanitizer-libc++
 # =================================
 # Security
 # =================================
@@ -74,3 +78,5 @@ build:release --copt -mllvm
 build:release --copt -inline-threshold=2500
 
 try-import %workspace%/user.bazelrc
+# import overrides for custom llvm installation
+try-import %workspace%/llvm.bazelrc

.gitignore

@@ -265,3 +265,4 @@ vbuild/
 
 # bazel
 user.bazelrc
+llvm.bazelrc

bazel/setup_llvm.sh

@@ -0,0 +1,33 @@
+# copied from Envoy project(https://github.com/envoyproxy/envoy/blob/main/bazel/setup_clang.sh)
+
+#!/usr/bin/env bash
+
+set -e
+
+BAZELRC_FILE="${BAZELRC_FILE:-./llvm.bazelrc}"
+
+LLVM_PREFIX=$1
+
+if [[ ! -e "${LLVM_PREFIX}/bin/llvm-config" ]]; then
+  echo "Error: cannot find local llvm-config in ${LLVM_PREFIX}."
+  exit 1
+fi
+
+PATH="$("${LLVM_PREFIX}"/bin/llvm-config --bindir):${PATH}"
+export PATH
+
+LLVM_VERSION="$(llvm-config --version)"
+LLVM_LIBDIR="$(llvm-config --libdir)"
+LLVM_TARGET="$(llvm-config --host-target)"
+
+RT_LIBRARY_PATH="${LLVM_LIBDIR}/clang/${LLVM_VERSION}/lib/${LLVM_TARGET}"
+
+echo "# Generated file, do not edit. If you want to disable custom llvm, just delete this file.
+build:llvm --action_env='PATH=${PATH}' --host_action_env='PATH=${PATH}'
+build:llvm --action_env='LLVM_CONFIG=${LLVM_PREFIX}/bin/llvm-config' --host_action_env='LLVM_CONFIG=${LLVM_PREFIX}/bin/llvm-config'
+build:llvm --repo_env='LLVM_CONFIG=${LLVM_PREFIX}/bin/llvm-config'
+build:llvm --linkopt='-L$(llvm-config --libdir)'
+build:llvm --linkopt='-Wl,-rpath,$(llvm-config --libdir)'
+
+build:llvm-sanitizers --linkopt='-L${RT_LIBRARY_PATH}'
+" >"${BAZELRC_FILE}"