Re: [RFC PATCH v1 09/43] helper-to-tcg: Introduce get-llvm-ir.py

[Richard Henderson <richard.henderson@linaro.org>]

On 11/20/24 19:49, Anton Johansson wrote:
> 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 <anjo@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

Is this not something that can be done in meson?


r~

> 
> 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())