Re: patch to fix PR70703

[Vladimir Makarov <vmakarov@redhat.com>]

On 04/05/2017 11:25 AM, Jakub Jelinek wrote:
> On Wed, Apr 05, 2017 at 11:11:54AM -0400, Vladimir Makarov wrote:
>> --- ira-color.c	(revision 246536)
>> +++ ira-color.c	(working copy)
>> @@ -1367,6 +1367,16 @@ update_costs_from_allocno (ira_allocno_t
>>   	      || ALLOCNO_ASSIGNED_P (another_allocno))
>>   	    continue;
>>   
>> +	  if (GET_MODE_SIZE (ALLOCNO_MODE (cp->second)) < GET_MODE_SIZE (mode))
>> +	    /* If we have different modes use the smallest one.  It is
>> +	       a sub-register move.  It is hard to predict what LRA
>> +	       will reload (the pseudo or its sub-register) but LRA
>> +	       will try to minimize the data movement.  Also for some
>> +	       register classes bigger modes might be invalid,
>> +	       e.g. DImode for AREG on x86.  For such cases the
>> +	       register move cost will be maximal. */
>> +	    mode = ALLOCNO_MODE (cp->second);
>> +	
>>   	  cost = (cp->second == allocno
>>   		  ? ira_register_move_cost[mode][rclass][aclass]
>>   		  : ira_register_move_cost[mode][aclass][rclass]);
>> @@ -1512,7 +1522,7 @@ update_conflict_hard_regno_costs (int *c
>>   		index = ira_class_hard_reg_index[aclass][hard_regno];
>>   		if (index < 0)
>>   		  continue;
>> -		cost = (int) ((unsigned) conflict_costs [i] * mult) / div;
>> +		cost = (int) (((long) conflict_costs [i] * mult) / div);
> If you want something wider than unsigned, wouldn't it be better to
> use HOST_WIDE_INT then?  Otherwise it will work differently between
> 32-bit and 64-bit hosts.
> Can any of those 3 values be negative?  If not, perhaps
> unsigned HOST_WIDE_INT?
>
Thank you for finding this, Jakub.  The overflow might happen only when 
65K is used for ira_register_move_cost which means an impossible move in 
most cases.  Still if it happens in rare cases, the behavior might be 
different for the native and a cross.

I'll correct the patch.