On Fri, 21 Oct 2016, kugan wrote:
>
>
> On 21/10/16 18:16, Richard Biener wrote:
> > On Fri, 21 Oct 2016, kugan wrote:
> >
> > > Hi,
> > >
> > > On 20/10/16 23:15, Jan Hubicka wrote:
> > > > > Hi Richard,
> > > > >
> > > > >
> > > > > On 20/10/16 18:41, Richard Biener wrote:
> > > > > > On Thu, 20 Oct 2016, kugan wrote:
> > > > > >
> > > > > > >
> > > > > > >
> > > > > > > On 20/10/16 01:26, Jan Hubicka wrote:
> > > > > > > > > > Would excluding weak symbols (I believe I can check
> > > > > > > > > > DECL_WEAK
> > > > > > > > > > for this)
> > > > > > > > > > good
> > > > > > > > > > enough. Or looking for acceptable subset would work?
> > > > > > > > >
> > > > > > > > > I think we should add a symtab helper to tell if
> > > > > > > > > address_nonzero_p
> > > > > > > > > (if
> > > > > > > > > that doesn't aleady exist).
> > > > > > > >
> > > > > > > > We have node->nonzero_address()
> > > > > > >
> > > > > > > Thanks for the pointer. Here is an attempt. Does this look OK?
> > > > > > >
> > > > > > > + if (TREE_CODE (arg) == ADDR_EXPR)
> > > > > > > + {
> > > > > > > + /* See if the AADR_EXPR is nonnull. */
> > > > > > > + varpool_node *node = NULL;
> > > > > > > + tree base = TREE_OPERAND (arg, 0);
> > > > > > > + base = get_base_address (base);
> > > > > > > +
> > > > > > > + if (decl_address_ip_invariant_p (base)
> > > > > > > + || !is_global_var (base))
> > > > > > > + {
> > > > > > > + /* If the symbol address is local or
> > > > > > > + constant. */
> > > > > >
> > > > > > "constant" doesn't matter. You want
> > > > > >
> > > > > > if (TREE_CODE (base) == CONST_DECL
> > > > > > || TREE_CODE (base) == PARM_DECL
> > > > > > || TREE_CODE (base) == RESULT_DECL)
> > > > > > addr_nonzero = true;
> > > > > > else if (VAR_P (base))
> > > > Better to check decl_in_symtab_p (decl)
> > > > > > addr_nonzero = ! is_global_var (base) || (varpool_node::get
> > > > > > (base)->nonzero_address ());
> > > > and symtab_node::get.
> > > >
> > > > I wonder if we can't unify the logic with tree_expr_nonzero_warnv_p
> > > > and corresponding vrp code?
> > > Are you saying that we should export tree_expr_nonzero_warnv_p and use
> > > here
> > > with the logic from above added to tree_expr_nonzero_warnv_p as shown in
> > > the
> > > attached patch?
> >
> > tree_single_nonzero_warnv_p already handles this correctly via
> > maybe_nonzero_address. And tree_single_nonzero_warnv_p is already
> > exported.
> Indeed. maybe_nonzero_address does look at node->nonzero_address () but we
> still seems to miss TREE_CODE (base) == PARM_DECL and TREE_CODE (base) ==
> RESULT_DECL.
Should be handled by
/* Function local objects are never NULL. */
if (DECL_P (base)
&& (DECL_CONTEXT (base)
&& TREE_CODE (DECL_CONTEXT (base)) == FUNCTION_DECL
&& auto_var_in_fn_p (base, DECL_CONTEXT (base))))
return true;
> Does the attached patch looks OK if no regressions?
+ else if (tree_single_nonzero_warnv_p (arg, &strict_overflow))
+ {
+ if (!strict_overflow)
+ addr_nonzero = true;
you don't need to care for strict_overflow here.
The patch is ok with that removed and the fold-const.c changes dropped.
Richard.
> Thanks,
> Kugan
>
>
> >
> > Richard.
> >
> > > Thanks,
> > > Kugan
> > >
> > > >
> > > > Otherwise the patch looks fine to me.
> > > > Honza
> > > >
> > >
> >
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
