[sac-user] sac-visualization tool

[Sunita Chandrasekaran]

Excellent Prof Scholz.
Thanks to you for the explanation, yes am getting a hang of what sac can do.
I think I will do some more coding myself to figure out what exactly is
happening so that I can match that with these outputs.

Something that I would definitely mention, is I am really v happy the way
the compiler got installed, the installation just didn't break and hardly
does this happen while installing a compiler or doing some
cross-compilation.

The compiler structure is well handled. Appreciate the sac team for this
commendable effort taken.

On Wed, Jun 11, 2008 at 8:09 PM, Sven-Bodo Scholz <S.Scholz at herts.ac.uk>
wrote:

> On Wed, Jun 11, 2008 at 03:32:39PM +0800, Sunita Chandrasekaran wrote:
> > Hi
> >
> > Does this sac2c compiler come with any graphic analyzer tool?
> > How do you view the graphs or the optimization effects? vcg?
>
> Hi Sunita,
>
> there are 2 things you might want to visualize: a) programs
> b) data (i.e. arrays)
>
> For the latter, we use off-the-shelve tools that exist as C libraries
> such as SDL or DISLIN.
>
> However, I assume that you are interested in the former since you
> mentioned vcg. AFAIK, there exists no graphical tol to visualise SaC
> programs. BUT, we have built-in support for printing optimised programs
> as SaC code itself. if you use 'sac2c -h' you will get lots of possible
> compiler flags include the BREAK-options -b<xyz>.
> Be aware though that the further "down" in the compilation process that
> you break the more difficult to relate to the original program the code
> becomes.
>
> Here a quick example to get started:
>
> Let's look at the following program:
>
>
> --------------------------------------------------------------------------------
> use Array: all;
>
> int main()
> {
>  a = 0;
>
>  for( i=0; i<10; i++) {
>    a += i;
>  }
>  return( a);
> }
>
> --------------------------------------------------------------------------------
>
> sac2c -b3 sunita.sac gives
>
>
> --------------------------------------------------------------------------------
> [.... lots of "gibberish"....]
> /*
>  *  function definitions (FUNDEFS)
>  */
>
> int _MAIN::main()
> /*
>  *  main ::  ---
>  */
> {
>  a = 0;
>  i = 0;
>  while (i Array::< 10)
>  {
>    a = Array::+( a, i);
>    i = Array::+( i, 1);
>  }
>  return( a);
> }
>
> --------------------------------------------------------------------------------
>
> sac2c -b6 sunita.sac gives
>
>
> --------------------------------------------------------------------------------
> [.... lots of "gibberish"....]
> /*
>  *  function definitions (FUNDEFS)
>  */
>
> /* Loop function */
> int _MAIN::_dup_5_main__Loop_0( int a, int i)
> /*
>  *  _dup_5_main__Loop_0 ::  ---
>  */
> {
>  int a__SSA0_3;
>  int a__SSA0_2;
>  int i__SSA0_1;
>  int a__SSA0_1;
>  int{1} _flat_2;
>  int{10} _flat_4;
>  bool _flat_3;
>
>  a__SSA0_1 = wrapper:Array::+( a, i);
>  _flat_2 = 1;
>  i__SSA0_1 = wrapper:Array::+( i, _flat_2);
>  _flat_4 = 10;
>  _flat_3 = wrapper:Array::<( i__SSA0_1, _flat_4);
>  if (_flat_3)
>  {
>    a__SSA0_2 = _MAIN::_dup_5_main__Loop_0( a__SSA0_1, i__SSA0_1);
>  }
>  else
>  {
>    /* empty */
>  }
>  a__SSA0_3 = ( _flat_3 ? a__SSA0_2 : a__SSA0_1 );
>  return( a__SSA0_3);
> }
>
> /* Cond function */
> int _MAIN::main__Cond_1( int{0} a, int{0} i, bool _flat_0)
> /*
>  *  main__Cond_1 ::  ---
>  */
> {
>  int a__SSA0_2;
>  int a__SSA0_1;
>
>  if (_flat_0)
>  {
>    a__SSA0_1 = _MAIN::_dup_5_main__Loop_0( a, i);
>  }
>  else
>  {
>    /* empty */
>  }
>  a__SSA0_2 = ( _flat_0 ? a__SSA0_1 : a );
>  return( a__SSA0_2);
> }
>
> int _MAIN::main()
> /*
>  *  main ::  ---
>  */
> {
>  int a__SSA0_2;
>  int a__SSA0_1;
>  bool _flat_0;
>  int{10} _flat_1;
>  int{0} i;
>  int{0} a;
>
>  a = 0;
>  i = 0;
>  _flat_1 = 10;
>  _flat_0 = wrapper:Array::<( i, _flat_1);
>  a__SSA0_1 = _MAIN::main__Cond_1( a, i, _flat_0);
>  a__SSA0_2 = _type_conv_( int, a__SSA0_1);
>  return( a__SSA0_2);
> }
>
> --------------------------------------------------------------------------------
>
> Here you can see that our compiler has transformed the loop into a tail
> recursive function called _MAIN::_dup_5_main__Loop_0. You can also see
> what the type inference has found out.
> Notice here as well that, on this level, we may have things that are
> exceed the set of user-level SaC. An example are types of the form
> int{0} a which indicates that a has the value 0!
>
> If we preceed and let the optimiser do its job, i.e.
> sac2c -b11 sunita.sac, we obtain:
>
>
> --------------------------------------------------------------------------------
> [ I am picking the relevant parts here :-) ]
>
> int _MAIN::main()
> /*
>  *  main ::  ---
>  */
> {
>  int a__SSA0_1;
>  int{0} a;
>
>  a = 0;
>  a__SSA0_1 = _MAIN::_dup_279__main__Loop_0( a, a);
>  return( a__SSA0_1);
> }
>
> int _MAIN::_dup_279__main__Loop_0( int a, int i)
> /*
>  *  _dup_279__main__Loop_0 ::  ---
>  */
> {
>  int _pinl_19__flat_69;
>  int _pinl_20__flat_69;
>  bool _pinl_21__flat_42;
>  int a__SSA0_3;
>  int a__SSA0_2;
>
>  _pinl_19__flat_69 = _add_SxS_( a, i);
>  _pinl_20__flat_69 = _add_SxS_( i, 1);
>  _pinl_21__flat_42 = _lt_SxS_( _pinl_20__flat_69, 10);
>  if (_pinl_21__flat_42)
>  {
>    a__SSA0_2 = _MAIN::_dup_279__main__Loop_0( _pinl_19__flat_69,
> _pinl_20__flat_69);
>  }
>  else
>  {
>    /* empty */
>  }
>  a__SSA0_3 = ( _pinl_21__flat_42 ? a__SSA0_2 : _pinl_19__flat_69 );
>  return( a__SSA0_3);
> }
>
>
> --------------------------------------------------------------------------------
> Usually, you do NOT want to see any code thereafter because our C-code
> generator is rather generic and therefore the intermediate code becomes
> ebven less readable to the "untrained eye" ;-)
>
> If you want to tweak the optimisation you could, for example, increase
> the loop unrolling threshold by using
>
> sac2c -maxlur 10 -b11 sunita.sac
>
> In which case you obtain:
>
> --------------------------------------------------------------------------------
> [...gibberish...]
>
> int{45} _MAIN::main()
> /*
>  *  main ::  ---
>  */
> {
>  int{45} a__SSA0_1;
>
>  a__SSA0_1 = 45;
>  return( a__SSA0_1);
> }
>
> --------------------------------------------------------------------------------
>
> ' hope that you were after some way to get this kind of information
> about about the optimisation results....
>
> Cheers,
>    Bodo
>
>
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