[RFC][IPA-VRP] ADDR_EXPR and nonnull

Richard Biener rguenther@suse.de
Fri Oct 21 07:16:00 GMT 2016


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.

Richard.

> Thanks,
> Kugan
> 
> > 
> > Otherwise the patch looks fine to me.
> > Honza
> > 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)



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