[IRA] Segfault in ira_costs.c:find_costs_and_classes for AVR target

[IRA] Segfault in ira_costs.c:find_costs_and_classes for AVR target

[Senthil Kumar Selvaraj]

Hi,

  gcc.c-torture/compile/pr34856.c and a couple of other tests segfault 
  for the AVR target. Looking at the code, I found that the
  x_ira_register_move_cost array[TImode] is NULL, while the code goes on
  to dereference it (ira_register_move_cost
  [ALLOCNO_MODE (a)][best][aclass] at line 1832).

  I looked at the code that populates the array, and found that it does
  explicitly allow the array to have NULL entries for certain modes,
  atleast during initialization.

  I'm not really sure how this should be fixed - is NULL valid or is the
  AVR target violating some invariant?

Regards
Senthil
  
  

[Ping, IRA] Segfault in ira_costs.c:find_costs_and_classes for AVR target

[Senthil Kumar Selvaraj]

Ping !

Regards
Senthil

On Thu, Dec 26, 2013 at 03:11:25PM +0530, Senthil Kumar Selvaraj wrote:
> Hi,
> 
>   gcc.c-torture/compile/pr34856.c and a couple of other tests segfault 
>   for the AVR target. Looking at the code, I found that the
>   x_ira_register_move_cost array[TImode] is NULL, while the code goes on
>   to dereference it (ira_register_move_cost
>   [ALLOCNO_MODE (a)][best][aclass] at line 1832).
> 
>   I looked at the code that populates the array, and found that it does
>   explicitly allow the array to have NULL entries for certain modes,
>   atleast during initialization.
> 
>   I'm not really sure how this should be fixed - is NULL valid or is the
>   AVR target violating some invariant?
> 
> Regards
> Senthil
>   
>   
> 

Re: [Ping, IRA] Segfault in ira_costs.c:find_costs_and_classes for AVR target

[Vladimir Makarov]

On 01/13/2014 03:54 AM, Senthil Kumar Selvaraj wrote:
> Ping !
>
> Regards
> Senthil
>
> On Thu, Dec 26, 2013 at 03:11:25PM +0530, Senthil Kumar Selvaraj wrote:
>> Hi,
>>
>>   gcc.c-torture/compile/pr34856.c and a couple of other tests segfault 
>>   for the AVR target. Looking at the code, I found that the
>>   x_ira_register_move_cost array[TImode] is NULL, while the code goes on
>>   to dereference it (ira_register_move_cost
>>   [ALLOCNO_MODE (a)][best][aclass] at line 1832).
>>
>>   I looked at the code that populates the array, and found that it does
>>   explicitly allow the array to have NULL entries for certain modes,
>>   atleast during initialization.
>>
>>   I'm not really sure how this should be fixed - is NULL valid or is the
>>   AVR target violating some invariant?
>>
>> Regards
>> Senthil
>>   
>>   
>>
Sorry for the delay with the answer.  NULL is not valid.  IRA calculates
many internal data structures.  So some people implemented a lazy
approach in such data structure calculation (NULL means that the data
were not calculated yet).  Probably, one place was missed or added
lately without checking that data were calculated.

I'll look at this and fix the problem this week.

Thanks for pointing this out, Senthil.

Re: [IRA] Segfault in ira_costs.c:find_costs_and_classes for AVR target

[Vladimir Makarov]

[-- Attachment #1: Type: text/plain, Size: 904 bytes --]

On 12/26/2013 04:41 AM, Senthil Kumar Selvaraj wrote:
> Hi,
>
>   gcc.c-torture/compile/pr34856.c and a couple of other tests segfault 
>   for the AVR target. Looking at the code, I found that the
>   x_ira_register_move_cost array[TImode] is NULL, while the code goes on
>   to dereference it (ira_register_move_cost
>   [ALLOCNO_MODE (a)][best][aclass] at line 1832).
>
>   I looked at the code that populates the array, and found that it does
>   explicitly allow the array to have NULL entries for certain modes,
>   atleast during initialization.
>
>   I'm not really sure how this should be fixed - is NULL valid or is the
>   AVR target violating some invariant?
>
The following patch fixes the problem.

Committed as rev. 206606.

2014-01-14  Vladimir Makarov  <vmakarov@redhat.com>

        * ira-costs.c (find_costs_and_classes): Add missed
        ira_init_register_move_cost_if_necessary.



[-- Attachment #2: z --]
[-- Type: text/plain, Size: 497 bytes --]

Index: ira-costs.c
===================================================================
--- ira-costs.c	(revision 206579)
+++ ira-costs.c	(working copy)
@@ -1827,6 +1827,7 @@ find_costs_and_classes (FILE *dump_file)
 		  int ind = cost_classes_ptr->index[aclass];
 
 		  ira_assert (ind >= 0);
+		  ira_init_register_move_cost_if_necessary (ALLOCNO_MODE (a));
 		  ira_add_allocno_pref (a, ira_class_hard_regs[best][0],
 					(a_costs[ind] - ALLOCNO_CLASS_COST (a))
 					/ (ira_register_move_cost