cpython/Tools/cases_generator/target_generator.py

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"""Generate targets for computed goto dispatch
Reads the instruction definitions from bytecodes.c.
Writes the table to opcode_targets.h by default.
"""
import argparse
from analyzer import (
Analysis,
analyze_files,
)
from generators_common import (
DEFAULT_INPUT,
ROOT,
)
from cwriter import CWriter
from typing import TextIO
DEFAULT_OUTPUT = ROOT / "Python/opcode_targets.h"
def write_opcode_targets(analysis: Analysis, out: CWriter) -> None:
"""Write header file that defines the jump target table"""
targets = ["&&_unknown_opcode,\n"] * 256
for name, op in analysis.opmap.items():
if op < 256:
targets[op] = f"&&TARGET_{name},\n"
out.emit("static void *opcode_targets[256] = {\n")
for target in targets:
out.emit(target)
out.emit("};\n")
arg_parser = argparse.ArgumentParser(
description="Generate the file with dispatch targets.",
formatter_class=argparse.ArgumentDefaultsHelpFormatter,
)
arg_parser.add_argument(
"-o", "--output", type=str, help="Generated code", default=DEFAULT_OUTPUT
)
arg_parser.add_argument(
"input", nargs=argparse.REMAINDER, help="Instruction definition file(s)"
)
if __name__ == "__main__":
args = arg_parser.parse_args()
if len(args.input) == 0:
args.input.append(DEFAULT_INPUT)
data = analyze_files(args.input)
with open(args.output, "w") as outfile:
out = CWriter(outfile, 0, False)
write_opcode_targets(data, out)