Re: Speedup invalid_mode_change_p

[Segher Boessenkool <segher at koffie dot nl>]

Jan Hubicka wrote:
> > Jan Hubicka wrote:
> >
> > > > 2003-03-04  Segher Boessenkool  <segher at koffie dot nl>
> > > >
> > > > 	* regclass.c (regclass): Try first if the subunion of
> > > > 	all best classes is allowed, and if so, use it, instead
> > > > 	of always computing the subunion of allowed best classes.

> Good thing is that we get best speed with both patches combined :)

Of course :)

> > > Can you please update it to avoid the goto statement (simply put the
> > > default loop into the body).

Updated version included.

> > Is goto not allowed in GCC at all?  I like it better this way.
>
> Well, there are some places goto is used, but it is usually in the
> switch statements and such beasts, not to simulate normal if
> conditional.

Well, we can discuss whether "goto" is a simulation of "else",
or the other way around ;)

> > > Also the default loop can be optimized
> > > slightly by first checking that the cost is not greater than best_cost
> > > we currently have.
> >
> > Will look at it.

Hrm, I forgot about this.


Tested on powerpc-unknown-linux-gnu.  If okay, please commit.
(Same changelog as before).


Segher



*** regclass.c~	Sat Mar 22 03:22:15 2003
--- regclass.c	Sat Mar 22 03:25:55 2003
*************** regclass (f, nregs, dump)
*** 1294,1320 ****
  	  if (optimize && !REG_N_REFS (i) && !REG_N_SETS (i))
  	    continue;

! 	  for (class = (int) ALL_REGS - 1; class > 0; class--)
  	    {
! 	      /* Ignore classes that are too small for this operand or
! 		 invalid for an operand that was auto-incremented.  */
! 	      if (!contains_reg_of_mode [class][PSEUDO_REGNO_MODE (i)]
  #ifdef FORBIDDEN_INC_DEC_CLASSES
! 		  || (in_inc_dec[i] && forbidden_inc_dec_class[class])
  #endif
  #ifdef CANNOT_CHANGE_MODE_CLASS
! 		  || invalid_mode_change_p (i, (enum reg_class) class,
! 					    PSEUDO_REGNO_MODE (i))
  #endif
  		  )
! 		;
! 	      else if (p->cost[class] < best_cost)
  		{
! 		  best_cost = p->cost[class];
! 		  best = (enum reg_class) class;
  		}
- 	      else if (p->cost[class] == best_cost)
- 		best = reg_class_subunion[(int) best][class];
  	    }

  	  /* Record the alternate register class; i.e., a class for which
--- 1294,1346 ----
  	  if (optimize && !REG_N_REFS (i) && !REG_N_SETS (i))
  	    continue;

! 	  /* Try the common case (that is, all cheapest classes are
! 	     allowed) first.  */
!
! 	  for (class = 1; class < (int) ALL_REGS; class++)
  	    {
! 	      if (p->cost[class] < best_cost)
! 		{
! 		  best_cost = p->cost[class];
! 		  best = (enum reg_class) class;
! 		}
! 	      else if (p->cost[class] == best_cost)
! 		best = reg_class_subunion[(int) best][class];
! 	    }
! 	  if (!contains_reg_of_mode[(int) best][PSEUDO_REGNO_MODE (i)]
  #ifdef FORBIDDEN_INC_DEC_CLASSES
! 	      || (in_inc_dec[i] && forbidden_inc_dec_class[(int) best])
  #endif
  #ifdef CANNOT_CHANGE_MODE_CLASS
! 	      || invalid_mode_change_p (i, best, PSEUDO_REGNO_MODE (i))
  #endif
  		  )
! 	    {
! 	      best_cost = (1 << (HOST_BITS_PER_INT - 2)) - 1;
! 	      best = ALL_REGS;
!
! 	      for (class = (int) ALL_REGS - 1; class > 0; class--)
  		{
! 		  /* Ignore classes that are too small for this operand or
! 		     invalid for an operand that was auto-incremented.  */
! 		  if (!contains_reg_of_mode [class][PSEUDO_REGNO_MODE (i)]
! #ifdef FORBIDDEN_INC_DEC_CLASSES
! 		      || (in_inc_dec[i] && forbidden_inc_dec_class[class])
! #endif
! #ifdef CANNOT_CHANGE_MODE_CLASS
! 		      || invalid_mode_change_p (i, (enum reg_class) class,
! 						PSEUDO_REGNO_MODE (i))
! #endif
! 		      )
! 		    ;
! 		  else if (p->cost[class] < best_cost)
! 		    {
! 		      best_cost = p->cost[class];
! 		      best = (enum reg_class) class;
! 		    }
! 		  else if (p->cost[class] == best_cost)
! 		    best = reg_class_subunion[(int) best][class];
  		}
  	    }

  	  /* Record the alternate register class; i.e., a class for which