feat: add LLVM setup script for modular installation

Add scripts/setup_llvm.sh to support LLVM installation and
configuration within containers. This script:

- Downloads LLVM source from GitHub when not mounted as a volume
- Installs build dependencies for LLVM compilation
- Provides a clean interface for LLVM integration

The script supports the INSTALL_LLVM environment variable with
'source' or 'skip' options, enabling flexible LLVM setup for
different container configurations.

This is part of the modular script architecture introduced in PR #115.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: cmagina

scripts/setup_llvm.sh

@@ -0,0 +1,90 @@
+#! /bin/bash -e
+
+trap "echo -e '\nScript interrupted. Exiting gracefully.'; exit 1" SIGINT
+
+# Copyright (C) 2024-2025 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+set -euo pipefail
+
+WORKSPACE=${WORKSPACE:-${HOME}}
+
+LLVM_DIR=${WORKSPACE}/llvm-project
+LLVM_REPO=https://github.com/llvm/llvm-project.git
+LLVM_BUILD_PATH=$LLVM_DIR/build
+
+setup_src() {
+	if [ ! -d "$LLVM_DIR" ]; then
+		echo "Cloning the LLVM Project repo $LLVM_REPO to $LLVM_DIR ..."
+		git clone "$LLVM_REPO" "$LLVM_DIR"
+		if [ ! -d "$LLVM_DIR" ]; then
+			echo "$LLVM_DIR not found. ERROR Cloning repository..."
+			exit 1
+		else
+			pushd "$LLVM_DIR" 1>/dev/null || exit 1
+			git fetch origin
+
+			[ -f "${HOME}"/.bashrc ] && source "${HOME}"/.bashrc
+
+			if [ -n "${LLVM_GITREF:-}" ]; then
+				git checkout "$LLVM_GITREF"
+			fi
+			popd 1>/dev/null
+		fi
+	fi
+
+	echo "Adding LLVM_BUILD_PATH to ${HOME}/.bashrc ..."
+	echo "export LLVM_BUILD_PATH=$LLVM_BUILD_PATH" >>"${HOME}/.bashrc"
+	echo "Run 'source ${HOME}/.bashrc' to update the current shell"
+}
+
+install_build_deps() {
+	pushd "$LLVM_DIR" 1>/dev/null || exit 1
+	if [ -f mlir/python/requirements.txt ]; then
+		echo "Installing LLVM build dependencies ..."
+		uv pip install -r mlir/python/requirements.txt
+	fi
+	popd 1>/dev/null
+}
+
+usage() {
+	cat >&2 <<EOF
+Usage: $(basename "$0") [COMMAND]
+    source    Download LLVM's source (if needed) and install the build deps
+EOF
+}
+
+##
+## Main
+##
+
+if [ $# -ne 1 ]; then
+	usage
+	exit 1
+fi
+
+COMMAND=${1,,}
+
+case $COMMAND in
+source)
+	echo "Setting up the environment for building LLVM ..."
+	setup_src
+	install_build_deps
+	;;
+*)
+	usage
+	exit 1
+	;;
+esac