scripts/gen-as-const.py

   1 #!/usr/bin/python3
   2 # Produce headers of assembly constants from C expressions.
   3 # Copyright (C) 2018-2022 Free Software Foundation, Inc.
   4 # This file is part of the GNU C Library.
   5 #
   6 # The GNU C Library is free software; you can redistribute it and/or
   7 # modify it under the terms of the GNU Lesser General Public
   8 # License as published by the Free Software Foundation; either
   9 # version 2.1 of the License, or (at your option) any later version.
  10 #
  11 # The GNU C Library is distributed in the hope that it will be useful,
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 # Lesser General Public License for more details.
  15 #
  16 # You should have received a copy of the GNU Lesser General Public
  17 # License along with the GNU C Library; if not, see
  18 # <https://www.gnu.org/licenses/>.
  19
  20 # The input to this script looks like:
  21 #       #cpp-directive ...
  22 #       NAME1
  23 #       NAME2 expression ...
  24 # A line giving just a name implies an expression consisting of just that name.
  25
  26 import argparse
  27
  28 import glibcextract
  29
  30
  31 def gen_test(sym_data):
  32     """Generate a test for the values of some C constants.
  33
  34     The first argument is as for glibcextract.compute_c_consts.
  35
  36     """
  37     out_lines = []
  38     for arg in sym_data:
  39         if isinstance(arg, str):
  40             if arg == 'START':
  41                 out_lines.append('#include <stdint.h>\n'
  42                                  '#include <stdio.h>\n'
  43                                  '#include <bits/wordsize.h>\n'
  44                                  '#if __WORDSIZE == 64\n'
  45                                  'typedef uint64_t c_t;\n'
  46                                  '# define U(n) UINT64_C (n)\n'
  47                                  '#else\n'
  48                                  'typedef uint32_t c_t;\n'
  49                                  '# define U(n) UINT32_C (n)\n'
  50                                  '#endif\n'
  51                                  'static int\n'
  52                                  'do_test (void)\n'
  53                                  '{\n'
  54                                  # Compilation test only, using static
  55                                  # assertions.
  56                                  '  return 0;\n'
  57                                  '}\n'
  58                                  '#include <support/test-driver.c>')
  59             else:
  60                 out_lines.append(arg)
  61             continue
  62         name = arg[0]
  63         value = arg[1]
  64         out_lines.append('_Static_assert (U (asconst_%s) == (c_t) (%s), '
  65                          '"value of %s");'
  66                          % (name, value, name))
  67     return '\n'.join(out_lines)
  68
  69
  70 def main():
  71     """The main entry point."""
  72     parser = argparse.ArgumentParser(
  73         description='Produce headers of assembly constants.')
  74     parser.add_argument('--cc', metavar='CC',
  75                         help='C compiler (including options) to use')
  76     parser.add_argument('--test', action='store_true',
  77                         help='Generate test case instead of header')
  78     parser.add_argument('--python', action='store_true',
  79                         help='Generate Python file instead of header')
  80     parser.add_argument('sym_file',
  81                         help='.sym file to process')
  82     args = parser.parse_args()
  83     sym_data = []
  84     with open(args.sym_file, 'r') as sym_file:
  85         started = False
  86         for line in sym_file:
  87             line = line.strip()
  88             if line == '':
  89                 continue
  90             # Pass preprocessor directives through.
  91             if line.startswith('#'):
  92                 sym_data.append(line)
  93                 continue
  94             words = line.split(maxsplit=1)
  95             if not started:
  96                 sym_data.append('START')
  97                 started = True
  98             # Separator.
  99             if words[0] == '--':
 100                 continue
 101             name = words[0]
 102             value = words[1] if len(words) > 1 else words[0]
 103             sym_data.append((name, value))
 104         if not started:
 105             sym_data.append('START')
 106     if args.test:
 107         print(gen_test(sym_data))
 108     elif args.python:
 109         consts = glibcextract.compute_c_consts(sym_data, args.cc)
 110         print('# GENERATED FILE\n'
 111               '\n'
 112               '# Constant definitions.\n'
 113               '# See gen-as-const.py for details.\n')
 114         print(''.join('%s = %s\n' % c for c in sorted(consts.items())), end='')
 115     else:
 116         consts = glibcextract.compute_c_consts(sym_data, args.cc)
 117         print(''.join('#define %s %s\n' % c for c in sorted(consts.items())), end='')
 118
 119 if __name__ == '__main__':
 120     main()