Introduces a new python helper script to convert a set of QEMU .c files to LLVM IR .ll using clang. Compile flags are found by looking at compile_commands.json, and llvm-link is used to link together all LLVM modules into a single module.
Signed-off-by: Anton Johansson <a...@rev.ng> --- subprojects/helper-to-tcg/get-llvm-ir.py | 143 +++++++++++++++++++++++ 1 file changed, 143 insertions(+) create mode 100755 subprojects/helper-to-tcg/get-llvm-ir.py diff --git a/subprojects/helper-to-tcg/get-llvm-ir.py b/subprojects/helper-to-tcg/get-llvm-ir.py new file mode 100755 index 0000000000..9ee5d0e136 --- /dev/null +++ b/subprojects/helper-to-tcg/get-llvm-ir.py @@ -0,0 +1,143 @@ +#!/usr/bin/env python3 + +## +## Copyright(c) 2024 rev.ng Labs Srl. All Rights Reserved. +## +## This program is free software; you can redistribute it and/or modify +## it under the terms of the GNU General Public License as published by +## the Free Software Foundation; either version 2 of the License, or +## (at your option) any later version. +## +## This program is distributed in the hope that it will be useful, +## but WITHOUT ANY WARRANTY; without even the implied warranty of +## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +## GNU General Public License for more details. +## +## You should have received a copy of the GNU General Public License +## along with this program; if not, see <http://www.gnu.org/licenses/>. +## + +import argparse +import json +import os +import shlex +import sys +import subprocess + + +def log(msg): + print(msg, file=sys.stderr) + + +def run_command(command): + proc = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT) + out = proc.communicate() + if proc.wait() != 0: + log(f"Command: {' '.join(command)} exited with {proc.returncode}\n") + log(f"output:\n{out}\n") + + +def find_compile_commands(compile_commands_path, clang_path, input_path, target): + with open(compile_commands_path, "r") as f: + compile_commands = json.load(f) + for compile_command in compile_commands: + path = compile_command["file"] + if os.path.basename(path) != os.path.basename(input_path): + continue + + os.chdir(compile_command["directory"]) + command = compile_command["command"] + + # If building multiple targets there's a chance + # input files share the same path and name. + # This could cause us to find the wrong compile + # command, we use the target path to distinguish + # between these. + if not target in command: + continue + + argv = shlex.split(command) + argv[0] = clang_path + + return argv + + raise ValueError(f"Unable to find compile command for {input_path}") + + +def generate_llvm_ir( + compile_commands_path, clang_path, output_path, input_path, target +): + command = find_compile_commands( + compile_commands_path, clang_path, input_path, target + ) + + flags_to_remove = { + "-ftrivial-auto-var-init=zero", + "-fzero-call-used-regs=used-gpr", + "-Wimplicit-fallthrough=2", + "-Wold-style-declaration", + "-Wno-psabi", + "-Wshadow=local", + } + + # Remove + # - output of makefile rules (-MQ,-MF target); + # - output of object files (-o target); + # - excessive zero-initialization of block-scope variables + # (-ftrivial-auto-var-init=zero); + # - and any optimization flags (-O). + for i, arg in reversed(list(enumerate(command))): + if arg in {"-MQ", "-o", "-MF"}: + del command[i : i + 2] + elif arg.startswith("-O") or arg in flags_to_remove: + del command[i] + + # Define a HELPER_TO_TCG macro for translation units wanting to + # conditionally include or exclude code during translation to TCG. + # Disable optimization (-O0) and make sure clang doesn't emit optnone + # attributes (-disable-O0-optnone) which inhibit further optimization. + # Optimization will be performed at a later stage in the helper-to-tcg + # pipeline. + command += [ + "-S", + "-emit-llvm", + "-DHELPER_TO_TCG", + "-O0", + "-Xclang", + "-disable-O0-optnone", + ] + if output_path: + command += ["-o", output_path] + + run_command(command) + + +def main(): + parser = argparse.ArgumentParser( + description="Produce the LLVM IR of a given .c file." + ) + parser.add_argument( + "--compile-commands", required=True, help="Path to compile_commands.json" + ) + parser.add_argument("--clang", default="clang", help="Path to clang.") + parser.add_argument("--llvm-link", default="llvm-link", help="Path to llvm-link.") + parser.add_argument("-o", "--output", required=True, help="Output .ll file path") + parser.add_argument( + "--target-path", help="Path to QEMU target dir. (e.q. target/i386)" + ) + parser.add_argument("inputs", nargs="+", help=".c file inputs") + args = parser.parse_args() + + outputs = [] + for input in args.inputs: + output = os.path.basename(input) + ".ll" + generate_llvm_ir( + args.compile_commands, args.clang, output, input, args.target_path + ) + outputs.append(output) + + run_command([args.llvm_link] + outputs + ["-S", "-o", args.output]) + + +if __name__ == "__main__": + sys.exit(main()) -- 2.45.2
