Re: [PATCH 8/9] Add TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID

[Richard Henderson <rth at redhat dot com>]

On 10/12/2015 09:10 PM, Richard Biener wrote:
> > > The check_loadstore change should instead have adjusted the
> > > flag_delete_null_pointer_checks guard in
> > > infer_nonnull_range_by_dereference.
> >
> >
> > Nope, that doesn't work.  You have to wait until you see the actual MEM
> > being dereferenced before you can look at it's address space.
>
> Well, as we are explicitely looking for the pointer 'op' we know the
> address-space
> beforehand, no?  TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (op)))?

No.  We don't even know what type we're looking for; we're merely looking for 
any use of NULL within any memory reference within STMT.

Specifically, when we're not looking for a specific SSA_NAME (which would be 
properly typed), we always pass in a plain (void *)0:

          bool by_dereference
            = infer_nonnull_range_by_dereference (stmt, null_pointer_node);



r~