Sets up a barebones meson.build that handles:

  1. Exposing command for converting .c files to LLVM IR by looking at
     compile_commads.json;

  2. Finding LLVM and verifying the LLVM version manually by running
     llvm-config, needed for dealing with multiple LLVM versions in a
     sane way;

  3. Building of helper-to-tcg.

A meson option is added to specify the path to llvm-config.

Signed-off-by: Anton Johansson <anjo@rev.ng>
---
 subprojects/helper-to-tcg/meson.build       | 70 +++++++++++++++++++++
 subprojects/helper-to-tcg/meson_options.txt |  2 +
 2 files changed, 72 insertions(+)
 create mode 100644 subprojects/helper-to-tcg/meson.build
 create mode 100644 subprojects/helper-to-tcg/meson_options.txt

diff --git a/subprojects/helper-to-tcg/meson.build b/subprojects/helper-to-tcg/meson.build
new file mode 100644
index 0000000000..af593ccdfe
--- /dev/null
+++ b/subprojects/helper-to-tcg/meson.build
@@ -0,0 +1,70 @@
+##
+##  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/>.
+##
+
+project('helper-to-tcg', ['cpp'],
+        meson_version: '>=0.63.0',
+        version: '0.7',
+        default_options: ['cpp_std=none', 'optimization=2'])
+
+python = import('python').find_installation()
+
+# Find LLVM using llvm-config manually.  Needed as meson struggles when multiple
+# versions of LLVM are installed on the same system (always returns the most
+# recent).
+llvm_config = get_option('llvm_config_path')
+cpp_args = [run_command(llvm_config, '--cxxflags').stdout().strip().split()]
+bindir = run_command(llvm_config, '--bindir').stdout().strip()
+ldflags = run_command(llvm_config, '--ldflags').stdout().strip().split()
+libs = run_command(llvm_config, '--libs').stdout().strip().split()
+syslibs = run_command(llvm_config, '--system-libs').stdout().strip().split()
+incdir = run_command(llvm_config, '--includedir').stdout().strip().split()
+version = run_command(llvm_config, '--version').stdout().strip()
+version_major = version.split('.')[0].to_int()
+
+# Check LLVM version manually
+if version_major < 10 or version_major > 14
+    error('LLVM version', version, 'not supported.')
+endif
+
+sources = [
+]
+
+clang = bindir / 'clang'
+llvm_link = bindir / 'llvm-link'
+
+get_llvm_ir_cmd = [python, meson.current_source_dir() / 'get-llvm-ir.py',
+                   '--compile-commands', 'compile_commands.json',
+                   '--clang', clang,
+                   '--llvm-link', llvm_link]
+
+# NOTE: Add -Wno-template-id-cdtor for GCC versions >= 14.  This warning is
+# related to a change in the C++ standard in C++20, that also applies to C++14
+# for some reason. See defect report DR2237 and commit
+#   https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=4b38d56dbac6742b038551a36ec80200313123a1
+# (temporary)
+compiler_info = meson.get_compiler('cpp')
+compiler = compiler_info.get_id()
+compiler_version = compiler_info.version().split('-').get(0)
+compiler_version_major = compiler_version.split('.').get(0)
+if compiler == 'gcc' and compiler_version_major.to_int() >= 14
+    cpp_args += ['-Wno-template-id-cdtor', '-Wno-missing-template-keyword']
+endif
+
+pipeline = executable('helper-to-tcg', sources,
+                      include_directories: ['passes', './', 'include'] + [incdir],
+                      link_args: [ldflags] + [libs] + [syslibs],
+                      cpp_args: cpp_args)
diff --git a/subprojects/helper-to-tcg/meson_options.txt b/subprojects/helper-to-tcg/meson_options.txt
new file mode 100644
index 0000000000..8a4b28a585
--- /dev/null
+++ b/subprojects/helper-to-tcg/meson_options.txt
@@ -0,0 +1,2 @@
+option('llvm_config_path', type : 'string', value : 'llvm-config',
+       description: 'override default llvm-config used for finding LLVM')
-- 
2.45.2