lld/test/MachO/tools/generate-cfi-funcs.py

   1 #!/usr/bin/env python
   2
   3 """Generate skeletal functions with a variety .cfi_ directives.
   4 The purpose is to produce object-file test inputs to lld with a
   5 variety of compact unwind encodings.
   6 """
   7 from __future__ import print_function
   8 import random
   9 import argparse
  10 import string
  11 from math import factorial
  12 from itertools import permutations
  13
  14 lsda_n = 0
  15 lsda_odds = 0.0
  16 func_size_low = 0x10
  17 func_size_high = 0x100
  18 saved_regs = ["%r15", "%r14", "%r13", "%r12", "%rbx"]
  19 saved_regs_combined = list(list(permutations(saved_regs, i)) for i in range(0, 6))
  20
  21
  22 def print_function(name):
  23     global lsda_odds
  24     have_lsda = random.random() < lsda_odds
  25     frame_size = random.randint(4, 64) * 16
  26     frame_offset = -random.randint(0, int(frame_size / 16 - 4)) * 16
  27     global func_size_low, func_size_high
  28     func_size = random.randint(func_size_low, func_size_high) * 0x10
  29     func_size_high += 1
  30     if func_size_high % 0x10 == 0:
  31         func_size_low += 1
  32
  33     print(
  34         """\
  35 ### %s frame=%d lsda=%s size=%d
  36     .section __TEXT,__text,regular,pure_instructions
  37     .p2align 4, 0x90
  38     .globl %s
  39 %s:
  40     .cfi_startproc"""
  41         % (name, frame_size, have_lsda, func_size, name, name)
  42     )
  43     if have_lsda:
  44         global lsda_n
  45         lsda_n += 1
  46         print(
  47             """\
  48     .cfi_personality 155, ___gxx_personality_v0
  49     .cfi_lsda 16, Lexception%d"""
  50             % lsda_n
  51         )
  52     print(
  53         """\
  54     pushq %%rbp
  55     .cfi_def_cfa_offset %d
  56     .cfi_offset %%rbp, %d
  57     movq %%rsp, %%rbp
  58     .cfi_def_cfa_register %%rbp"""
  59         % (frame_size, frame_offset + 6 * 8)
  60     )
  61     print(
  62         """\
  63     .fill %d
  64     popq %%rbp
  65     retq
  66     .cfi_endproc
  67 """
  68         % (func_size - 6)
  69     )
  70
  71     if have_lsda:
  72         print(
  73             """\
  74     .section __TEXT,__gcc_except_tab
  75     .p2align 2
  76 Lexception%d:
  77     .space 0x10
  78 """
  79             % lsda_n
  80         )
  81     return func_size
  82
  83
  84 def random_seed():
  85     """Generate a seed that can easily be passed back in via --seed=STRING"""
  86     return "".join(random.choice(string.ascii_lowercase) for i in range(10))
  87
  88
  89 def main():
  90     parser = argparse.ArgumentParser(
  91         description=__doc__,
  92         epilog="""\
  93 Function sizes begin small then monotonically increase.  The goal is
  94 to produce early pages that are full and later pages that are less
  95 than full, in order to test handling for both cases.  Full pages
  96 contain the maximum of 1021 compact unwind entries for a total page
  97 size = 4 KiB.
  98
  99 Use --pages=N or --functions=N to control the size of the output.
 100 Default is --pages=2, meaning produce at least two full pages of
 101 compact unwind entries, plus some more. The calculation is sloppy.
 102 """,
 103     )
 104     parser.add_argument(
 105         "--seed",
 106         type=str,
 107         default=random_seed(),
 108         help="Seed the random number generator",
 109     )
 110     parser.add_argument(
 111         "--pages", type=int, default=2, help="Number of compact-unwind pages"
 112     )
 113     parser.add_argument(
 114         "--functions", type=int, default=None, help="Number of functions to generate"
 115     )
 116     parser.add_argument(
 117         "--encodings",
 118         type=int,
 119         default=127,
 120         help="Maximum number of unique unwind encodings (default = 127)",
 121     )
 122     parser.add_argument(
 123         "--lsda",
 124         type=int,
 125         default=0,
 126         help="Percentage of functions with personality & LSDA (default = 10",
 127     )
 128     args = parser.parse_args()
 129     random.seed(args.seed)
 130     p2align = 14
 131     global lsda_odds
 132     lsda_odds = args.lsda / 100.0
 133
 134     print(
 135         """\
 136 ### seed=%s lsda=%f p2align=%d
 137     .section __TEXT,__text,regular,pure_instructions
 138     .p2align %d, 0x90
 139 """
 140         % (args.seed, lsda_odds, p2align, p2align)
 141     )
 142
 143     size = 0
 144     base = 1 << p2align
 145     if args.functions:
 146         for n in range(args.functions):
 147             size += print_function("x%08x" % (size + base))
 148     else:
 149         while size < (args.pages << 24):
 150             size += print_function("x%08x" % (size + base))
 151
 152     print(
 153         """\
 154     .section __TEXT,__text,regular,pure_instructions
 155     .globl _main
 156     .p2align 4, 0x90
 157 _main:
 158     retq
 159
 160     .p2align 4, 0x90
 161 ___gxx_personality_v0:
 162     retq
 163 """
 164     )
 165
 166
 167 if __name__ == "__main__":
 168     main()