gdb/testsuite/gdb.reverse/finish-reverse-next.c

   1 /* This testcase is part of GDB, the GNU debugger.
   2
   3    Copyright 2012-2024 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 /* The reverse finish command should return from a function and stop on
  19    the first instruction of the source line where the function call is made.
  20    Specifically, the behavior should match doing a reverse next from the
  21    first instruction in the function.  GDB should only require one reverse
  22    step or next statement to reach the previous source code line.
  23
  24    This test verifies the fix for gdb bugzilla:
  25
  26    https://sourceware.org/bugzilla/show_bug.cgi?id=29927
  27
  28    PowerPC supports two entry points to a function.  The normal entry point
  29    is called the local entry point (LEP).  The alternate entry point is called
  30    the global entry point (GEP).  The GEP is only used if the table of
  31    contents (TOC) value stored in register r2 needs to be setup prior to
  32    execution starting at the LEP.  A function call via a function pointer
  33    will entry via the GEP.  A normal function call will enter via the LEP.
  34
  35    This test has been expanded to include tests to verify the reverse-finish
  36    command works properly if the function is called via the GEP.  The original
  37    test only verified the reverse-finish command for a normal call that used
  38    the LEP.  */
  39
  40 int
  41 function2 (int a, int b)
  42 {
  43   int ret = 0;
  44   ret = ret + a + b;
  45   return ret;
  46 }
  47
  48 int
  49 function1 (int a, int b)   // FUNCTION1
  50 {
  51   int ret = 0;
  52   int (*funp) (int, int) = &function2;
  53   /* The assembly code for this function when compiled for PowerPC is as
  54      follows:
  55
  56      0000000010000758 <function1>:
  57      10000758:  02 10 40 3c     lis     r2,4098        <- GEP
  58      1000075c:  00 7f 42 38     addi    r2,r2,32512
  59      10000760:  a6 02 08 7c     mflr    r0             <- LEP
  60      10000764:  10 00 01 f8     std     r0,16(r1)
  61      ....
  62
  63      When the function is called on PowerPC with function1 (a, b) the call
  64      enters at the Local Entry Point (LEP).  When the function is called via
  65      a function pointer, the Global Entry Point (GEP) for function1 is used.
  66      The GEP sets up register 2 before reaching the LEP.
  67   */
  68   ret = funp (a + 1, b + 2);
  69   return ret;
  70 }
  71
  72 int
  73 main(int argc, char* argv[])
  74 {
  75   int a, b;
  76   int (*funp) (int, int) = &function1;
  77
  78   /* Call function via Local Entry Point (LEP).  */
  79
  80   a = 1;
  81   b = 5;
  82
  83   function1 (a, b);   // CALL VIA LEP
  84
  85   /* Call function via Global Entry Point (GEP).  */
  86   a = 10;
  87   b = 50;
  88
  89   funp (a, b);        // CALL VIA GEP
  90   return 0;
  91 }