cpython/Python/makeopcodetargets.py

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#! /usr/bin/env python
"""Generate C code for the jump table of the threaded code interpreter
(for compilers supporting computed gotos or "labels-as-values", such as gcc).
"""
import os
import sys
# 2023-04-27(warsaw): Pre-Python 3.12, this would catch ImportErrors and try to
# import imp, and then use imp.load_module(). The imp module was removed in
# Python 3.12 (and long deprecated before that), and it's unclear under what
# conditions this import will now fail, so the fallback was simply removed.
from importlib.machinery import SourceFileLoader
def find_module(modname):
"""Finds and returns a module in the local dist/checkout.
"""
modpath = os.path.join(
os.path.dirname(os.path.dirname(__file__)), "Lib", modname + ".py")
return SourceFileLoader(modname, modpath).load_module()
def write_contents(f):
"""Write C code contents to the target file object.
"""
opcode = find_module('opcode')
_opcode_metadata = find_module('_opcode_metadata')
targets = ['_unknown_opcode'] * 256
for opname, op in opcode.opmap.items():
if not opcode.is_pseudo(op):
targets[op] = "TARGET_%s" % opname
next_op = 1
for opname in _opcode_metadata._specialized_instructions:
while targets[next_op] != '_unknown_opcode':
next_op += 1
targets[next_op] = "TARGET_%s" % opname
f.write("static void *opcode_targets[256] = {\n")
f.write(",\n".join([" &&%s" % s for s in targets]))
f.write("\n};\n")
def main():
if len(sys.argv) >= 3:
sys.exit("Too many arguments")
if len(sys.argv) == 2:
target = sys.argv[1]
else:
target = "Python/opcode_targets.h"
with open(target, "w") as f:
write_contents(f)
print("Jump table written into %s" % target)
if __name__ == "__main__":
main()