gmon/tst-mcount-overflow.c

   1 /* Test program to trigger mcount overflow in profiling collection.
   2    Copyright (C) 2017-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 /* Program with sufficiently complex, yet pointless, call graph
  20    that it will trigger an mcount overflow, when you set the
  21    minarcs/maxarcs tunables to very low values. */
  22
  23 #define PREVENT_TAIL_CALL asm volatile ("")
  24
  25 /* Calls REP(n) macro 16 times, for n=0..15.
  26  * You need to define REP(n) before using this.
  27  */
  28 #define REPS \
  29   REP(0) REP(1) REP(2) REP(3) REP(4) REP(5) REP(6) REP(7) \
  30   REP(8) REP(9) REP(10) REP(11) REP(12) REP(13) REP(14) REP(15)
  31
  32 /* Defines 16 leaf functions named f1_0 to f1_15 */
  33 #define REP(n) \
  34   __attribute__ ((noinline, noclone, weak)) void f1_##n (void) {};
  35 REPS
  36 #undef REP
  37
  38 /* Calls all 16 leaf functions f1_* in succession */
  39 __attribute__ ((noinline, noclone, weak)) void
  40 f2 (void)
  41 {
  42 # define REP(n) f1_##n();
  43   REPS
  44 # undef REP
  45   PREVENT_TAIL_CALL;
  46 }
  47
  48 /* Defines 16 functions named f2_0 to f2_15, which all just call f2 */
  49 #define REP(n) \
  50   __attribute__ ((noinline, noclone, weak)) void \
  51   f2_##n (void) { f2(); PREVENT_TAIL_CALL; };
  52 REPS
  53 #undef REP
  54
  55 __attribute__ ((noinline, noclone, weak)) void
  56 f3 (int count)
  57 {
  58   for (int i = 0; i < count; ++i)
  59     {
  60       /* Calls f1_0(), f2_0(), f1_1(), f2_1(), f3_0(), etc */
  61 #     define REP(n) f1_##n(); f2_##n();
  62       REPS
  63 #     undef REP
  64     }
  65 }
  66
  67 int
  68 main (void)
  69 {
  70   f3 (1000);
  71   return 0;
  72 }