ICE with atomic_store

[Andrew MacLeod]

On 06/18/2014 12:59 PM, Basile Starynkevitch wrote:
> Hello All,
>
> The following code:
>
>     #include <stdlib.h>
>     struct s1_st {
>       char* i_name;
>       struct s1_st* i_foo;
>     };
>
>     void clear_s1 (struct s1_st*s)
>     {
>       __atomic_store(s->i_name, NULL, __ATOMIC_SEQ_CST);
>     }
>
> gives an ICE when compiled (on Debian/Sid/amd64) by GCC 4.8 & 4.9 (I did not test it on the trunk yet)
>
> (For some strange reason, probably on my side, I'm not able to change the password on bugzilla. So I'm reporting that bug here, sorry for the inconvenience).
>
> Cheers.
>

First, thats an error... the second parameter to __atomic_store must be 
a pointer to memory, not NULL. We store the contents of that location to 
s->i_name. Perhaps it was meant to be __atomic_store_n () ?

That doesn't excuse the exception however. Looks like void type has a 
NULL TYPE_SIZE_UNIT, which causes tree_to_uhwi to segfault. could be 
fixed with something like this.. try it. I get

a.c: In function ‘clear_s1’:
a.c:9:6: error: size mismatch in argument 2 of ‘__atomic_store’
__atomic_store(s->i_name, NULL, __ATOMIC_SEQ_CST);

Thoroughly untested of course :-)

Andrew



-------------- next part --------------

	* c-common,c (get_atomic_generic_size):  Handle pointer to 0 size.

Index: c-family/c-common.c
===================================================================
*** c-family/c-common.c	(revision 211758)
--- c-family/c-common.c	(working copy)
*************** get_atomic_generic_size (location_t loc,
*** 10462,10467 ****
--- 10462,10468 ----
      {
        int size;
        tree type = TREE_TYPE ((*params)[x]);
+       tree type_size;
        /* __atomic_compare_exchange has a bool in the 4th position, skip it.  */
        if (n_param == 6 && x == 3)
          continue;
*************** get_atomic_generic_size (location_t loc,
*** 10471,10477 ****
  		    function);
  	  return 0;
  	}
!       size = tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (type)));
        if (size != size_0)
  	{
  	  error_at (loc, "size mismatch in argument %d of %qE", x + 1,
--- 10472,10480 ----
  		    function);
  	  return 0;
  	}
! 
!       type_size = TYPE_SIZE_UNIT (TREE_TYPE (type));
!       size = type_size ? tree_to_uhwi (type_size) : 0;
        if (size != size_0)
  	{
  	  error_at (loc, "size mismatch in argument %d of %qE", x + 1,