[Bug rtl-optimization/23585] [4.0 regression] mem_fun* code fine with -O1, bus error with -O2

["pinskia at physics dot uc dot edu" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #9 from pinskia at gcc dot gnu dot org  2005-10-11 13:55 -------
Subject: Re:  [4.0 regression] mem_fun* code fine with -O1, bus error with -O2


On Oct 11, 2005, at 9:51 AM, ebotcazou at gcc dot gnu dot org wrote:

>
>
> ------- Comment #8 from ebotcazou at gcc dot gnu dot org  2005-10-11 
> 13:51 -------
>> Yes, I think the problem is in delay slot scheduling too. COND_EXPR 
>> means that
>> either branch must not be evaluated because it could be illegal; if 
>> you hoist a
>> mem from a branch into the delay slot of the condition, you are 
>> effectively
>> partially evaluting the branch.
>
> Yes, that makes sense.  At the moment the predicate used in reorg.c is
> may_trap_p so we would need to detect faulting instructions too.

may_trap_p is the correct thing as it should detect this instruction as
trapping:


       /* Memory ref can trap unless it's a static var or a stack slot.  
*/
     case MEM:
       if (MEM_NOTRAP_P (x))
         return 0;
       return rtx_addr_can_trap_p (XEXP (x, 0));


-- Pinski


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23585