python · Fidget-Spinner · Dec 17, 2025 · Dec 17, 2025 · Dec 17, 2025 · Dec 17, 2025
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-12-17-20-31-09.gh-issue-139757.6DWxeQ.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-12-17-20-31-09.gh-issue-139757.6DWxeQ.rst
@@ -0,0 +1 @@
+Fix building JIT stencils on free-threaded builds.
@@ -95,6 +95,7 @@ class InstructionKind(enum.Enum):
    JUMP = enum.auto()
    LONG_BRANCH = enum.auto()
    SHORT_BRANCH = enum.auto()
+    CALL = enum.auto()
    RETURN = enum.auto()
    SMALL_CONST_1 = enum.auto()
    SMALL_CONST_2 = enum.auto()
@@ -182,6 +183,8 @@ class Optimizer:
    # Two groups (instruction and target):
    _re_branch: typing.ClassVar[re.Pattern[str]] = _RE_NEVER_MATCH
    # One group (target):
+    _re_call: typing.ClassVar[re.Pattern[str]] = _RE_NEVER_MATCH
+    # One group (target):
    _re_jump: typing.ClassVar[re.Pattern[str]] = _RE_NEVER_MATCH
    # No groups:
    _re_return: typing.ClassVar[re.Pattern[str]] = _RE_NEVER_MATCH
@@ -225,6 +228,11 @@ def __post_init__(self) -> None:
                assert inst.target is not None
                block.target = self._lookup_label(inst.target)
                assert block.fallthrough
+            elif inst.kind == InstructionKind.CALL:
+                # A block ending in a call has a target and return point after call:
+                assert inst.target is not None
+                block.target = self._lookup_label(inst.target)
+                assert block.fallthrough
            elif inst.kind == InstructionKind.JUMP:
                # A block ending in a jump has a target and no fallthrough:
                assert inst.target is not None
@@ -256,6 +264,10 @@ def _parse_instruction(self, line: str) -> Instruction:
            target = match["target"]
            name = line[: -len(target)].strip()
            kind = InstructionKind.JUMP
+        elif match := self._re_call.match(line):
+            target = match["target"]
+            name = line[: -len(target)].strip()
+            kind = InstructionKind.CALL
        elif match := self._re_return.match(line):
            name = line
            kind = InstructionKind.RETURN
@@ -463,6 +475,8 @@ def _fixup_external_labels(self) -> None:
        for index, block in enumerate(self._blocks()):
            if block.target and block.fallthrough:
                branch = block.instructions[-1]
+                if branch.kind == InstructionKind.CALL:
+                    continue
                assert branch.is_branch()
                target = branch.target
                assert target is not None
@@ -566,6 +580,8 @@ class OptimizerAArch64(Optimizer):  # pylint: disable = too-few-public-methods
        rf"\s*(?P<instruction>{'|'.join(_branch_patterns)})\s+(.+,\s+)*(?P<target>[\w.]+)"
    )

+    # https://developer.arm.com/documentation/ddi0406/b/Application-Level-Architecture/Instruction-Details/Alphabetical-list-of-instructions/BL--BLX--immediate-
+    _re_call = re.compile(r"\s*blx?\s+(?P<target>[\w.]+)")
    # https://developer.arm.com/documentation/ddi0602/2025-03/Base-Instructions/B--Branch-
    _re_jump = re.compile(r"\s*b\s+(?P<target>[\w.]+)")
    # https://developer.arm.com/documentation/ddi0602/2025-09/Base-Instructions/RET--Return-from-subroutine-
@@ -628,6 +644,8 @@ class OptimizerX86(Optimizer):  # pylint: disable = too-few-public-methods
    _re_branch = re.compile(
        rf"\s*(?P<instruction>{'|'.join(_X86_BRANCHES)})\s+(?P<target>[\w.]+)"
    )
+    # https://www.felixcloutier.com/x86/call
+    _re_call = re.compile(r"\s*callq?\s+(?P<target>[\w.]+)")
    # https://www.felixcloutier.com/x86/jmp
    _re_jump = re.compile(r"\s*jmp\s+(?P<target>[\w.]+)")
    # https://www.felixcloutier.com/x86/ret
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Fix building JIT stencils on free-threaded builds.