fix fallout of pr22051-2.c on arm

[Richard Biener]

On Thu, 4 Aug 2016, Prathamesh Kulkarni wrote:

> Hi,
> The attached patch fixes pr22051-2.c which regressed due to
> r238754. Matthew, could you please confirm if this patch fixes the
> test-case for you ?
> 
> Bootstrapped and tested on x86_64-unknown-linux-gnu.
> Cross tested on arm*-*-*.
> OK for trunk ?

Note that if function pointer types are really the issue then
you also need to handle METHOD_TYPE, thus sth like

  && ! FUNC_OR_METHOD_TYPE_P (TREE_TYPE (TREE_TYPE (@0))

please also add a comment for this non-obvious thing.  I believe
we should simply apply function pointer canonicalization for
comparisons early during gimplification - exposing this target
detail only during RTL expansion makes generic optimization hard.

Ok with those changes.

Thanks,
Richard.