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      1 /* Copyright 2020-2024 Free Software Foundation, Inc.
      2 
      3    This program is free software; you can redistribute it and/or modify
      4    it under the terms of the GNU General Public License as published by
      5    the Free Software Foundation; either version 3 of the License, or
      6    (at your option) any later version.
      7 
      8    This program is distributed in the hope that it will be useful,
      9    but WITHOUT ANY WARRANTY; without even the implied warranty of
     10    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     11    GNU General Public License for more details.
     12 
     13    You should have received a copy of the GNU General Public License
     14    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
     15 
     16 /* This tests GDB's handling of the DWARF is-stmt field in the line table.
     17 
     18    This field is used when many addresses all represent the same source
     19    line.  The address(es) at which it is suitable to place a breakpoint for
     20    a line are marked with is-stmt true, while address(es) that are not good
     21    places to place a breakpoint are marked as is-stmt false.
     22 
     23    In order to build a reproducible test and exercise GDB's is-stmt
     24    support, we will be generating our own DWARF.  The test will contain a
     25    series of C source lines, ensuring that we get a series of assembler
     26    instructions.  Each C source line will be given an assembler label,
     27    which we use to generate a fake line table.
     28 
     29    In this fake line table each assembler block is claimed to represent a
     30    single C source line, however, we will toggle the is-stmt flag.  We can
     31    then debug this with GDB and test the handling of is-stmt.  */
     32 
     33 /* Used to insert labels with which we can build a fake line table.  */
     34 #define LL(N) asm ("line_label_" #N ": .globl line_label_" #N)
     35 
     36 volatile int var;
     37 volatile int bar;
     38 
     39 int
     40 main ()
     41 {					/* main prologue */
     42   asm ("main_label: .globl main_label");
     43   LL (1);
     44   var = 99;				/* main, set var to 99 */
     45   bar = 99;
     46 
     47   LL (2);
     48   var = 0;				/* main, set var to 0 */
     49   bar = 0;
     50 
     51   LL (3);
     52   var = 1;				/* main, set var to 1 */
     53   bar = 1;
     54 
     55   LL (4);
     56   var = 2;				/* main, set var to 2 */
     57   bar = 2;
     58 
     59   LL (5);
     60   return 0;				/* main end */
     61 }
     62