title: compiling error "impossible constraint in 'asm'"
body: <p>I tried to compile Csmith on my "SunOS sun4v 5.10" system, but I got errors like these:</p>
  
  <pre><code>platform.cpp: In function 'long unsigned int platform_gen_seed()':
  platform.cpp:78: error: impossible constraint in 'asm'
  </code></pre>
  
  <p>Could anyone tell where is the mistake?</p>
  
  <pre><code>#if (TARGET_CPU_powerpc == 1 || TARGET_CPU_powerpc64 == 1)
  /*For PPC, got from:
  http://lists.ozlabs.org/pipermail/linuxppc-dev/1999-October/003889.html
  */
  static unsigned long long read_time(void) {
      unsigned long long retval;
      unsigned long junk;
      __asm__ __volatile__ ("\n\
  1:  mftbu %1\n\
      mftb %L0\n\
      mftbu %0\n\
      cmpw %0,%1\n\
      bne 1b"
      : "=r" (retval), "=r" (junk));
      return retval;
  }
  #else
  #ifdef WIN32
  static unsigned __int64 read_time(void) {
          unsigned l, h;
          _asm {rdtsc    
          mov l, eax  
          mov h, edx 
          }
          return (h &lt;&lt; 32) + l ;
  }
  #else
  static long long read_time(void) {
          long long l;
          asm volatile(   "rdtsc\n\t"
                  : "=A" (l)
          );
          return l;
  }
  #endif
  #endif
  
  unsigned long platform_gen_seed()
  {
      return (long) read_time();
  }
  </code></pre>