1  ///////////////////////////////////////////////////////////////////////////////
       2  //
       3  /// \file       bcj_test.c
       4  /// \brief      Source code of compress_prepared_bcj_*
       5  ///
       6  /// This is a simple program that should make the compiler to generate
       7  /// PC-relative branches, jumps, and calls. The compiled files can then
       8  /// be used to test the branch conversion filters. Note that this program
       9  /// itself does nothing useful.
      10  ///
      11  /// Compiling: gcc -std=c99 -fPIC -c bcj_test.c
      12  /// Don't optimize or strip.
      13  //
      14  //  Author:     Lasse Collin
      15  //
      16  //  This file has been put into the public domain.
      17  //  You can do whatever you want with this file.
      18  //
      19  ///////////////////////////////////////////////////////////////////////////////
      20  
      21  extern int jump(int a, int b);
      22  
      23  
      24  extern int
      25  call(int a, int b)
      26  {
      27  	if (a < b)
      28  		a = jump(a, b);
      29  
      30  	return a;
      31  }
      32  
      33  
      34  extern int
      35  jump(int a, int b)
      36  {
      37  	// The loop generates conditional jump backwards.
      38  	while (1) {
      39  		if (a < b) {
      40  			a *= 2;
      41  			a += 3 * b;
      42  			break;
      43  		} else {
      44  			// Put enough code here to prevent JMP SHORT on x86.
      45  			a += b;
      46  			a /= 2;
      47  			b += b % 5;
      48  			a -= b / 3;
      49  			b = 2 * b + a - 1;
      50  			a *= b + a + 1;
      51  			b += a - 1;
      52  			a += b * 2 - a / 5;
      53  		}
      54  	}
      55  
      56  	return a;
      57  }
      58  
      59  
      60  int
      61  main(int argc, char **argv)
      62  {
      63  	int a = call(argc, argc + 1);
      64  	return a == 0;
      65  }