1  #! /usr/bin/env python
       2  """Generate C code for the jump table of the threaded code interpreter
       3  (for compilers supporting computed gotos or "labels-as-values", such as gcc).
       4  """
       5  
       6  import os
       7  import sys
       8  
       9  
      10  try:
      11      from importlib.machinery import SourceFileLoader
      12  except ImportError:
      13      import imp
      14  
      15      def find_module(modname):
      16          """Finds and returns a module in the local dist/checkout.
      17          """
      18          modpath = os.path.join(
      19              os.path.dirname(os.path.dirname(__file__)), "Lib")
      20          return imp.load_module(modname, *imp.find_module(modname, [modpath]))
      21  else:
      22      def find_module(modname):
      23          """Finds and returns a module in the local dist/checkout.
      24          """
      25          modpath = os.path.join(
      26              os.path.dirname(os.path.dirname(__file__)), "Lib", modname + ".py")
      27          return SourceFileLoader(modname, modpath).load_module()
      28  
      29  
      30  def write_contents(f):
      31      """Write C code contents to the target file object.
      32      """
      33      opcode = find_module('opcode')
      34      targets = ['_unknown_opcode'] * 256
      35      targets[255] = "TARGET_DO_TRACING"
      36      for opname, op in opcode.opmap.items():
      37          targets[op] = "TARGET_%s" % opname
      38      next_op = 1
      39      for opname in opcode._specialized_instructions:
      40          while targets[next_op] != '_unknown_opcode':
      41              next_op += 1
      42          targets[next_op] = "TARGET_%s" % opname
      43      f.write("static void *opcode_targets[256] = {\n")
      44      f.write(",\n".join(["    &&%s" % s for s in targets]))
      45      f.write("\n};\n")
      46  
      47  
      48  def main():
      49      if len(sys.argv) >= 3:
      50          sys.exit("Too many arguments")
      51      if len(sys.argv) == 2:
      52          target = sys.argv[1]
      53      else:
      54          target = "Python/opcode_targets.h"
      55      with open(target, "w") as f:
      56          write_contents(f)
      57      print("Jump table written into %s" % target)
      58  
      59  
      60  if __name__ == "__main__":
      61      main()