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Re: [RFC][IPA-VRP] ADDR_EXPR and nonnull




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.

Does the attached patch looks OK if no regressions?

Thanks,
Kugan



Richard.

Thanks,
Kugan


Otherwise the patch looks fine to me.
Honza



Attachment: p3.txt
Description: Text document


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