Re: Bootstrap comparison failure on i686-linux

[Franz Sirl <Franz dot Sirl-kernel at lauterbach dot com>]

On Saturday 06 January 2001 21:35, Andreas Jaeger wrote:
> >>>>> Franz Sirl writes:
>
> [...]
>
>  > I have similar problems on powerpc-linux-gnu and for me the differences
>  > start in the loop dump. After realizing that I checked out the recent
>  > loop patches from Michael Hayes and I think I found a difference against
>  > the original code, realloced memory is not cleared anymore. VARRAY_GROW
>  > handled that automatically before. The appended patch fixes that, but I
>  > don't know yet if it really fixes the comparison failure, bootstrap is
>  > still running. You might wanna try the patch nevertheless though. I'll
>  > check it in under the "obvious fix rule" if it fixes my comparison
>  > failure.
>
> Uninitialized memory might explain why I can't reproduce it reliable.
> I just tried another bootstrap (but with --enable-languages=c) and it
> was successfull.

I can't even try that, cause cp/tree.o is affected for me.

>  > Franz.
>  >
>  > 	* loop.c (load_mems_and_recount_loop_regs_set): Clear memory added by
>  > 	realloc.
>  >
>  >
>  > Index: loop.c
>  > ===================================================================
>  > RCS file: /cvs/gcc/gcc/gcc/loop.c,v
>  > retrieving revision 1.314
>  > diff -u -p -r1.314 loop.c
>  > --- loop.c	2001/01/06 03:24:57	1.314
>  > +++ loop.c	2001/01/06 19:33:46
>  > @@ -8724,9 +8724,11 @@ load_mems_and_recount_loop_regs_set (loo
>  >  	  /* Grow the array.  */
>
> regs-> array = (struct loop_reg *)
>
>  >  	    xrealloc (regs->array, regs->size * sizeof (*regs->array));
>  > +	  for (i = old_nregs; i < regs->num; i++)
>  > +	    memset (&regs->array[i], 0, sizeof (*regs->array));
>  >  	}
>  >
>  > -      for (i = 0; i < regs->num; i++)
>  > +      for (i = 0; i < old_nregs; i++)
>  >  	{
>
> regs-> array[i].set_in_loop = 0;
> regs-> array[i].may_not_optimize = 0;
>
> Instead of your patch, why can't we clear all members in the second
> loop?  The second loop doesn't clear n_times_set and moved-once -
> clearing them also should be the better way to fix it.  Or should
> those members not get reset?

Well, that's the way it was before Michael Hayes reorganized the code.

Anyway, it doesn't fix my bootstrap, so the problem must be somewhere else 
:-(.

Franz.