Known bugs in the Fork compiler

Status: July 2005

• Tracing: The instrumentation code may cause some bugs that do not occur if the tracing feature is switched off. In principle, it is sufficient for visualisation if only user code is instrumented, plus the synchronisation routines in lib/forklib2.asm that are explicitly instrumented. Hence, the -T option in lib/Makefile could be removed.

• Structs as return values are not supported.

• double's are not implemented. For simplicity, double is aliased to float.

• shmalloc function: If the permanent shared heap size is exceeded, shmalloc emits an error message but does not return a NULL pointer. To remedy this bug, insert in lib/shmalloc.c after line 71 a new line (72) as follows:

     71     p = alloc( N + 2 );
     72     if (!p) return NULL;  // CK bugfix 050714
  

  touch lib/stdlib.c and recompile the library (cd lib; make).
  Thanks to C. Meigen for reporting the bug.

• Scanf function: scanf() erroneously terminates reading strings (%s) when the character 'v' is encountered in the input. I have no explanation and no workaround/fix for this bug yet. [M. Eriksson, 17/5/2005]

• Cosinus function: The reference to the shared constant variable PId2 in the library file lib/math.c is broken for unknown reasons. As a workaround, in file lib/math.c, the definition of the cos() function (lines 60-63) should be replaced by

  float cos( float x )   /* compute cosine function */
  {
    return sin( x + 1.5707963 );
  }
  

  Thanks to C. Meigen for reporting the bug.

• Ln function: Line 145 of lib/math.c

    register int i;
  

  should be replaced by

    register int i = 0;
  

  Thanks to M. Eriksson for reporting the bug and providing the correction. [11/7/2005]

  Note that this bug also affected other functions in lib/math.c, such as exp() and pow().

• Command-line parameters passed with the pramsim command are not forwarded to main(). [C. Meigen, 1/7/2005]