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From 96c59a6e427fab32d0bca89b77febca8cba8aada Mon Sep 17 00:00:00 2001
From: danigm <daniel.garcia@suse.com>
Date: Tue, 7 Oct 2025 16:54:31 +0200
Subject: [PATCH] gh-138497: Support LLVM_VERSION configuration via env
(#138498)
Co-authored-by: Savannah Ostrowski <savannah@python.org>
---
...-09-04-12-16-31.gh-issue-138497.Y_5YXh.rst | 4 ++
Tools/jit/README.md | 2 +-
Tools/jit/_llvm.py | 49 ++++++++++++-------
Tools/jit/_targets.py | 19 +++++--
Tools/jit/build.py | 3 ++
configure | 2 +-
configure.ac | 2 +-
7 files changed, 56 insertions(+), 25 deletions(-)
create mode 100644 Misc/NEWS.d/next/Build/2025-09-04-12-16-31.gh-issue-138497.Y_5YXh.rst
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2025-09-04-12-16-31.gh-issue-138497.Y_5YXh.rst
@@ -0,0 +1,4 @@
+The LLVM version used by the JIT at build time can now be modified using
+the ``LLVM_VERSION`` environment variable. Use this at your own risk, as
+there is only one officially supported LLVM version. For more information,
+please check ``Tools/jit/README.md``.
--- a/Tools/jit/README.md
+++ b/Tools/jit/README.md
@@ -9,7 +9,7 @@
The JIT compiler does not require end users to install any third-party dependencies, but part of it must be *built* using LLVM[^why-llvm]. You are *not* required to build the rest of CPython using LLVM, or even the same version of LLVM (in fact, this is uncommon).
-LLVM version 19 is required. Both `clang` and `llvm-readobj` need to be installed and discoverable (version suffixes, like `clang-19`, are okay). It's highly recommended that you also have `llvm-objdump` available, since this allows the build script to dump human-readable assembly for the generated code.
+LLVM version 19 is the officially supported version. You can modify if needed using the `LLVM_VERSION` env var during configure. Both `clang` and `llvm-readobj` need to be installed and discoverable (version suffixes, like `clang-19`, are okay). It's highly recommended that you also have `llvm-objdump` available, since this allows the build script to dump human-readable assembly for the generated code.
It's easy to install all of the required tools:
--- a/Tools/jit/_llvm.py
+++ b/Tools/jit/_llvm.py
@@ -10,8 +10,8 @@
import _targets
-_LLVM_VERSION = 19
-_LLVM_VERSION_PATTERN = re.compile(rf"version\s+{_LLVM_VERSION}\.\d+\.\d+\S*\s+")
+
+_LLVM_VERSION = "21"
_EXTERNALS_LLVM_TAG = "llvm-19.1.7.0"
_P = typing.ParamSpec("_P")
@@ -56,53 +56,66 @@
@_async_cache
-async def _check_tool_version(name: str, *, echo: bool = False) -> bool:
+async def _check_tool_version(
+ name: str, llvm_version: str, *, echo: bool = False
+) -> bool:
output = await _run(name, ["--version"], echo=echo)
- return bool(output and _LLVM_VERSION_PATTERN.search(output))
+ _llvm_version_pattern = re.compile(rf"version\s+{llvm_version}\.\d+\.\d+\S*\s+")
+ return bool(output and _llvm_version_pattern.search(output))
@_async_cache
-async def _get_brew_llvm_prefix(*, echo: bool = False) -> str | None:
- output = await _run("brew", ["--prefix", f"llvm@{_LLVM_VERSION}"], echo=echo)
+async def _get_brew_llvm_prefix(llvm_version: str, *, echo: bool = False) -> str | None:
+ output = await _run("brew", ["--prefix", f"llvm@{llvm_version}"], echo=echo)
return output and output.removesuffix("\n")
@_async_cache
-async def _find_tool(tool: str, *, echo: bool = False) -> str | None:
+async def _find_tool(tool: str, llvm_version: str, *, echo: bool = False) -> str | None:
# Unversioned executables:
path = tool
- if await _check_tool_version(path, echo=echo):
+ if await _check_tool_version(path, llvm_version, echo=echo):
return path
# Versioned executables:
- path = f"{tool}-{_LLVM_VERSION}"
- if await _check_tool_version(path, echo=echo):
+ path = f"{tool}-{llvm_version}"
+ if await _check_tool_version(path, llvm_version, echo=echo):
return path
# PCbuild externals:
externals = os.environ.get("EXTERNALS_DIR", _targets.EXTERNALS)
path = os.path.join(externals, _EXTERNALS_LLVM_TAG, "bin", tool)
- if await _check_tool_version(path, echo=echo):
+ if await _check_tool_version(path, llvm_version, echo=echo):
return path
# Homebrew-installed executables:
- prefix = await _get_brew_llvm_prefix(echo=echo)
+ prefix = await _get_brew_llvm_prefix(llvm_version, echo=echo)
if prefix is not None:
path = os.path.join(prefix, "bin", tool)
- if await _check_tool_version(path, echo=echo):
+ if await _check_tool_version(path, llvm_version, echo=echo):
return path
# Nothing found:
return None
async def maybe_run(
- tool: str, args: typing.Iterable[str], echo: bool = False
+ tool: str,
+ args: typing.Iterable[str],
+ echo: bool = False,
+ llvm_version: str = _LLVM_VERSION,
) -> str | None:
"""Run an LLVM tool if it can be found. Otherwise, return None."""
- path = await _find_tool(tool, echo=echo)
+
+ path = await _find_tool(tool, llvm_version, echo=echo)
return path and await _run(path, args, echo=echo)
-async def run(tool: str, args: typing.Iterable[str], echo: bool = False) -> str:
+async def run(
+ tool: str,
+ args: typing.Iterable[str],
+ echo: bool = False,
+ llvm_version: str = _LLVM_VERSION,
+) -> str:
"""Run an LLVM tool if it can be found. Otherwise, raise RuntimeError."""
- output = await maybe_run(tool, args, echo=echo)
+
+ output = await maybe_run(tool, args, echo=echo, llvm_version=llvm_version)
if output is None:
- raise RuntimeError(f"Can't find {tool}-{_LLVM_VERSION}!")
+ raise RuntimeError(f"Can't find {tool}-{llvm_version}!")
return output
--- a/Tools/jit/_targets.py
+++ b/Tools/jit/_targets.py
@@ -48,6 +48,7 @@
debug: bool = False
verbose: bool = False
cflags: str = ""
+ llvm_version: str = _llvm._LLVM_VERSION
known_symbols: dict[str, int] = dataclasses.field(default_factory=dict)
pyconfig_dir: pathlib.Path = pathlib.Path.cwd().resolve()
@@ -76,7 +77,9 @@
async def _parse(self, path: pathlib.Path) -> _stencils.StencilGroup:
group = _stencils.StencilGroup()
args = ["--disassemble", "--reloc", f"{path}"]
- output = await _llvm.maybe_run("llvm-objdump", args, echo=self.verbose)
+ output = await _llvm.maybe_run(
+ "llvm-objdump", args, echo=self.verbose, llvm_version=self.llvm_version
+ )
if output is not None:
# Make sure that full paths don't leak out (for reproducibility):
long, short = str(path), str(path.name)
@@ -94,7 +97,9 @@
"--sections",
f"{path}",
]
- output = await _llvm.run("llvm-readobj", args, echo=self.verbose)
+ output = await _llvm.run(
+ "llvm-readobj", args, echo=self.verbose, llvm_version=self.llvm_version
+ )
# --elf-output-style=JSON is only *slightly* broken on Mach-O...
output = output.replace("PrivateExtern\n", "\n")
output = output.replace("Extern\n", "\n")
@@ -161,7 +166,7 @@
# Allow user-provided CFLAGS to override any defaults
*shlex.split(self.cflags),
]
- await _llvm.run("clang", args, echo=self.verbose)
+ await _llvm.run("clang", args, echo=self.verbose, llvm_version=self.llvm_version)
return await self._parse(o)
async def _build_stencils(self) -> dict[str, _stencils.StencilGroup]:
@@ -209,6 +214,8 @@
if not self.stable:
warning = f"JIT support for {self.triple} is still experimental!"
request = "Please report any issues you encounter.".center(len(warning))
+ if self.llvm_version != _llvm._LLVM_VERSION:
+ request = f"Warning! Building with an LLVM version other than {_llvm._LLVM_VERSION} is not supported."
outline = "=" * len(warning)
print("\n".join(["", outline, warning, request, outline, ""]))
digest = f"// {self._compute_digest()}\n"
--- a/Tools/jit/build.py
+++ b/Tools/jit/build.py
@@ -42,6 +42,7 @@
parser.add_argument(
"--cflags", help="additional flags to pass to the compiler", default=""
)
+ parser.add_argument("--llvm-version", help="LLVM version to use")
args = parser.parse_args()
for target in args.target:
target.debug = args.debug
@@ -49,6 +50,8 @@
target.verbose = args.verbose
target.cflags = args.cflags
target.pyconfig_dir = args.pyconfig_dir
+ if args.llvm_version:
+ target.llvm_version = args.llvm_version
target.build(
comment=comment,
force=args.force,
--- a/configure.ac
+++ b/configure.ac
@@ -2787,7 +2787,7 @@
[],
[AS_VAR_APPEND([CFLAGS_NODIST], [" $jit_flags"])
AS_VAR_SET([REGEN_JIT_COMMAND],
- ["\$(PYTHON_FOR_REGEN) \$(srcdir)/Tools/jit/build.py ${ARCH_TRIPLES:-$host} --output-dir . --pyconfig-dir . --cflags=\"$CFLAGS_JIT\""])
+ ["\$(PYTHON_FOR_REGEN) \$(srcdir)/Tools/jit/build.py ${ARCH_TRIPLES:-$host} --output-dir . --pyconfig-dir . --cflags=\"$CFLAGS_JIT\" --llvm-version=\"$LLVM_VERSION\""])
AS_VAR_SET([JIT_STENCILS_H], ["jit_stencils.h"])
AS_VAR_IF([Py_DEBUG],
[true],
|
