Re: Another switch testcase failure with enable-checking

[Jan Hubicka <jh at suse dot cz>]

> Jan Hubicka wrote:
> >>All,
> >>
> >>I've stumbled on another interesting switch testcase which triggers an 
> >>enable-checking abort
> >>on all the ports I've tried so far x86, mips, sh, s390.
> >>
> >>For this testcase I get at -O2 with enable-checking enabled
> >>
> >>bug2.c: In function `foo':
> >>bug2.c:28: warning: verify_flow_info: Wrong probability of edge 1->19 
> >>10008
> >>bug2.c:28: internal compiler error: verify_flow_info failed
> >>
> >>Jan any ideas what's wrong with the edge probability calcs
> >
> >
> >This is commonly just some roundoff error around.  I will track it down
> >tomorrow.
> >
> Yes it's an around-off error somewhere I tracked down where rhe bad 
> probability is
> being set. It's in cfg.c:redirect_edge_succ_nodup the stmt
> 
> 	"s->probability += e->probability;"
> 
> results in a probability > 10000 because s->probability is 9942 and 
> e->probaility
> is 566 which add up to 10008.
> 
> This happens on any target where the switch gets collapsed to an 
> if-then-else.
Hi,
I am attaching patch I will install shortly.
Regstested/bootstrapped i386

Honza

Sat Aug 10 19:43:09 CEST 2002  Jan Hubicka  <jh@suse.cz>
			       Graham Scott
	* cfg.c (redirect_edge_succ_nodup): Avoid overflows due to roundoff
	errors.

*** cfg.c.old	Sat Aug 10 20:55:22 2002
--- cfg.c	Sat Aug 10 20:55:46 2002
*************** redirect_edge_succ_nodup (e, new_succ)
*** 455,460 ****
--- 455,462 ----
      {
        s->flags |= e->flags;
        s->probability += e->probability;
+       if (s->probability > REG_BR_PROB_BASE)
+ 	s->probability = REG_BR_PROB_BASE;
        s->count += e->count;
        remove_edge (e);
        e = s;