[Bug ipa/65270] [5 regression] ICF needs to match TYPE attributes on memory accesses

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65270

--- Comment #23 from rguenther at suse dot de <rguenther at suse dot de> ---
On Thu, 5 Mar 2015, hubicka at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65270
> 
> --- Comment #19 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
> I tried to construct a testcase for __restrict__ case:
> int var;
> const int *varptr=&var;
> const int *__restrict__ varptr2=&var;
> 
>  int *__restrict__ varptr3 = &var;
>  int *__restrict__ varptr4 = &var;
> 
> int *
> return_valptr(int i)
> {
>   return varptr[i];
> }
> int * __restrict__
> return_valptr2(int i)
> {
>   return varptr2[i];
> }
> int
> testrestrict ()
> {
>   int *ptr = return_valptr (0);
>   *ptr = 0;
>   *varptr3 = 1;
>   return *ptr;
> }
> int
> testrestrict2 ()
> {
>   int *ptr = return_valptr2 (0);
>   *ptr = 0;
>   *varptr3 = 1;
>   return *ptr;
> }
> int
> testrestrict4 ()
> {
>   *varptr4 = 0;
>   *varptr3 = 1;
>   return *varptr4;
> }
> 
> Here I would like restrict2 to return uncondtional 0, because ptr is taken from
> a restrict pointer in a global var.  For whatever reason this optimization is
> not happening (it happens in testrestrict4). So perhaps we are safe to
> completely ignore restircts on vars, because we never get the flag in through
> folding.

We don't get it ever from folding.  Only IPA PTA looks at global 
constructors, local PTA doesn't - but that's a missed optimization
at least for readonly vars.  Can you please open a new bug with the above
testcase?