https://github.com/python/cpython/commit/61e759c2ee521ccf817293d6150094b618fbeee5
commit: 61e759c2ee521ccf817293d6150094b618fbeee5
branch: main
author: Mark Shannon <[email protected]>
committer: markshannon <[email protected]>
date: 2025-10-23T16:45:57+01:00
summary:
GH-135904: JIT compiler: Support 19 bit branch instructions on AArch64 for
Mach-O. (GH-140453)
* Insert labels into assembly for custom relocation during stencil creation.
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2025-10-22-11-30-16.gh-issue-135904.3WE5oW.rst
M Tools/jit/_optimizers.py
M Tools/jit/_stencils.py
M Tools/jit/_targets.py
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2025-10-22-11-30-16.gh-issue-135904.3WE5oW.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2025-10-22-11-30-16.gh-issue-135904.3WE5oW.rst
new file mode 100644
index 00000000000000..b52a57dba4acae
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2025-10-22-11-30-16.gh-issue-135904.3WE5oW.rst
@@ -0,0 +1,3 @@
+Add special labels to the assembly created during stencil creation to
+support relocations that the native object file format does not support.
+Specifically, 19 bit branches for AArch64 in Mach-O object files.
diff --git a/Tools/jit/_optimizers.py b/Tools/jit/_optimizers.py
index 866417398b0ba5..0adc550ba5e84c 100644
--- a/Tools/jit/_optimizers.py
+++ b/Tools/jit/_optimizers.py
@@ -9,7 +9,7 @@
_RE_NEVER_MATCH = re.compile(r"(?!)")
# Dictionary mapping branch instructions to their inverted branch instructions.
# If a branch cannot be inverted, the value is None:
-_X86_BRANCHES = {
+_X86_BRANCH_NAMES = {
# https://www.felixcloutier.com/x86/jcc
"ja": "jna",
"jae": "jnae",
@@ -37,7 +37,11 @@
"loopz": None,
}
# Update with all of the inverted branches, too:
-_X86_BRANCHES |= {v: k for k, v in _X86_BRANCHES.items() if v}
+_X86_BRANCH_NAMES |= {v: k for k, v in _X86_BRANCH_NAMES.items() if v}
+# No custom relocations needed
+_X86_BRANCHES: dict[str, tuple[str | None, str | None]] = {
+ k: (v, None) for k, v in _X86_BRANCH_NAMES.items()
+}
_AARCH64_COND_CODES = {
# https://developer.arm.com/documentation/dui0801/b/CJAJIHAD?lang=en
@@ -58,12 +62,15 @@
"hi": "ls",
"ls": "hi",
}
+# MyPy doesn't understand that a invariant variable can be initialized by a
covariant value
+CUSTOM_AARCH64_BRANCH19: str | None = "CUSTOM_AARCH64_BRANCH19"
+
# Branches are either b.{cond} or bc.{cond}
-_AARCH64_BRANCHES = {
- "b." + cond: ("b." + inverse if inverse else None)
+_AARCH64_BRANCHES: dict[str, tuple[str | None, str | None]] = {
+ "b." + cond: (("b." + inverse if inverse else None),
CUSTOM_AARCH64_BRANCH19)
for (cond, inverse) in _AARCH64_COND_CODES.items()
} | {
- "bc." + cond: ("bc." + inverse if inverse else None)
+ "bc." + cond: (("bc." + inverse if inverse else None),
CUSTOM_AARCH64_BRANCH19)
for (cond, inverse) in _AARCH64_COND_CODES.items()
}
@@ -113,7 +120,8 @@ class Optimizer:
r'\s*(?P<label>[\w."$?@]+):'
)
# Override everything that follows in subclasses:
- _branches: typing.ClassVar[dict[str, str | None]] = {}
+ _supports_external_relocations = True
+ _branches: typing.ClassVar[dict[str, tuple[str | None, str | None]]] = {}
# Two groups (instruction and target):
_re_branch: typing.ClassVar[re.Pattern[str]] = _RE_NEVER_MATCH
# One group (target):
@@ -170,7 +178,10 @@ def _preprocess(self, text: str) -> str:
def _invert_branch(cls, line: str, target: str) -> str | None:
match = cls._re_branch.match(line)
assert match
- inverted = cls._branches.get(match["instruction"])
+ inverted_reloc = cls._branches.get(match["instruction"])
+ if inverted_reloc is None:
+ return None
+ inverted = inverted_reloc[0]
if not inverted:
return None
(a, b), (c, d) = match.span("instruction"), match.span("target")
@@ -302,27 +313,45 @@ def _remove_redundant_jumps(self) -> None:
block.fallthrough = True
block.instructions.pop()
+ def _fixup_external_labels(self) -> None:
+ if self._supports_external_relocations:
+ # Nothing to fix up
+ return
+ for block in self._blocks():
+ if block.target and block.fallthrough:
+ branch = block.instructions[-1]
+ match = self._re_branch.match(branch)
+ assert match is not None
+ target = match["target"]
+ reloc = self._branches[match["instruction"]][1]
+ if reloc is not None and not
target.startswith(self.label_prefix):
+ name = target[len(self.symbol_prefix) :]
+ block.instructions[-1] = (
+ f"// target='{target}' prefix='{self.label_prefix}'"
+ )
+ block.instructions.append(
+ f"{self.symbol_prefix}{reloc}_JIT_RELOCATION_{name}:"
+ )
+ a, b = match.span("target")
+ branch = "".join([branch[:a], "0", branch[b:]])
+ block.instructions.append(branch)
+
def run(self) -> None:
"""Run this optimizer."""
self._insert_continue_label()
self._mark_hot_blocks()
self._invert_hot_branches()
self._remove_redundant_jumps()
+ self._fixup_external_labels()
self.path.write_text(self._body())
-# Mach-O does not support the 19 bit branch locations needed for branch
reordering
-class OptimizerAArch64_MachO(Optimizer): # pylint: disable =
too-few-public-methods
- """aarch64-apple-darwin"""
-
- #
https://developer.arm.com/documentation/ddi0602/2025-03/Base-Instructions/B--Branch-
- _re_jump = re.compile(r"\s*b\s+(?P<target>[\w.]+)")
-
-
class OptimizerAArch64(Optimizer): # pylint: disable = too-few-public-methods
- """aarch64-pc-windows-msvc/aarch64-unknown-linux-gnu"""
+
"""aarch64-pc-windows-msvc/aarch64-apple-darwin/aarch64-unknown-linux-gnu"""
_branches = _AARCH64_BRANCHES
+ # Mach-O does not support the 19 bit branch locations needed for branch
reordering
+ _supports_external_relocations = False
_re_branch = re.compile(
rf"\s*(?P<instruction>{'|'.join(_AARCH64_BRANCHES)})\s+(.+,\s+)*(?P<target>[\w.]+)"
)
diff --git a/Tools/jit/_stencils.py b/Tools/jit/_stencils.py
index 16bc1ea4e17e6b..777db7366b186b 100644
--- a/Tools/jit/_stencils.py
+++ b/Tools/jit/_stencils.py
@@ -58,6 +58,7 @@ class HoleValue(enum.Enum):
"ARM64_RELOC_PAGE21": "patch_aarch64_21r",
"ARM64_RELOC_PAGEOFF12": "patch_aarch64_12",
"ARM64_RELOC_UNSIGNED": "patch_64",
+ "CUSTOM_AARCH64_BRANCH19": "patch_aarch64_19r",
# x86_64-pc-windows-msvc:
"IMAGE_REL_AMD64_REL32": "patch_x86_64_32rx",
# aarch64-pc-windows-msvc:
@@ -221,6 +222,17 @@ class StencilGroup:
_got: dict[str, int] = dataclasses.field(default_factory=dict, init=False)
_trampolines: set[int] = dataclasses.field(default_factory=set, init=False)
+ def convert_labels_to_relocations(self) -> None:
+ for name, hole_plus in self.symbols.items():
+ if isinstance(name, str) and "_JIT_RELOCATION_" in name:
+ _, offset = hole_plus
+ reloc, target = name.split("_JIT_RELOCATION_")
+ value, symbol = symbol_to_value(target)
+ hole = Hole(
+ int(offset), typing.cast(_schema.HoleKind, reloc), value,
symbol, 0
+ )
+ self.code.holes.append(hole)
+
def process_relocations(self, known_symbols: dict[str, int]) -> None:
"""Fix up all GOT and internal relocations for this stencil group."""
for hole in self.code.holes.copy():
diff --git a/Tools/jit/_targets.py b/Tools/jit/_targets.py
index 7ff7c4fba49652..dcc0abaf23f16d 100644
--- a/Tools/jit/_targets.py
+++ b/Tools/jit/_targets.py
@@ -218,6 +218,7 @@ async def _build_stencils(self) -> dict[str,
_stencils.StencilGroup]:
tasks.append(group.create_task(coro, name=opname))
stencil_groups = {task.get_name(): task.result() for task in tasks}
for stencil_group in stencil_groups.values():
+ stencil_group.convert_labels_to_relocations()
stencil_group.process_relocations(self.known_symbols)
return stencil_groups
@@ -565,7 +566,7 @@ def get_target(host: str) -> _COFF32 | _COFF64 | _ELF |
_MachO:
if re.fullmatch(r"aarch64-apple-darwin.*", host):
host = "aarch64-apple-darwin"
condition = "defined(__aarch64__) && defined(__APPLE__)"
- optimizer = _optimizers.OptimizerAArch64_MachO
+ optimizer = _optimizers.OptimizerAArch64
target = _MachO(host, condition, optimizer=optimizer)
elif re.fullmatch(r"aarch64-pc-windows-msvc", host):
host = "aarch64-pc-windows-msvc"
_______________________________________________
Python-checkins mailing list -- [email protected]
To unsubscribe send an email to [email protected]
https://mail.python.org/mailman3//lists/python-checkins.python.org
Member address: [email protected]
