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

[kugan <kugan.vivekanandarajah@linaro.org>]

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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?

Thanks,
Kugan

>
> Otherwise the patch looks fine to me.
> Honza
>

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diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 89ed89d..6fa42c9 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -8954,7 +8954,7 @@ mask_with_tz (tree type, const wide_int &x, const wide_int &y)
    is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
    change *STRICT_OVERFLOW_P.  */
 
-static bool
+bool
 tree_expr_nonzero_warnv_p (tree t, bool *strict_overflow_p)
 {
   tree type = TREE_TYPE (t);
@@ -13402,9 +13402,15 @@ tree_single_nonzero_warnv_p (tree t, bool *strict_overflow_p)
 	  return true;
 
 	/* Constants are never weak.  */
-	if (CONSTANT_CLASS_P (base))
+	if (CONSTANT_CLASS_P (base)
+	    || TREE_CODE (base) == PARM_DECL
+	    || TREE_CODE (base) == RESULT_DECL)
 	  return true;
 
+	if (VAR_P (base)
+	    && (!is_global_var (base)
+		|| varpool_node::get (base)->nonzero_address ()))
+	  return true;
 	return false;
       }
 
diff --git a/gcc/fold-const.h b/gcc/fold-const.h
index bc22c88..a19a27a 100644
--- a/gcc/fold-const.h
+++ b/gcc/fold-const.h
@@ -198,6 +198,7 @@ extern tree fold_build_pointer_plus_loc (location_t loc, tree ptr, tree off);
 
 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF.  */
 extern tree fold_build_pointer_plus_hwi_loc (location_t loc, tree ptr, HOST_WIDE_INT off);
+extern bool tree_expr_nonzero_warnv_p (tree t, bool *strict_overflow_p);
 
 #define fold_build_pointer_plus_hwi(p,o) \
 	fold_build_pointer_plus_hwi_loc (UNKNOWN_LOCATION, p, o)
diff --git a/gcc/ipa-prop.c b/gcc/ipa-prop.c
index 353b638..55a2ea1 100644
--- a/gcc/ipa-prop.c
+++ b/gcc/ipa-prop.c
@@ -1670,9 +1670,20 @@ ipa_compute_jump_functions_for_edge (struct ipa_func_body_info *fbi,
 
       if (POINTER_TYPE_P (TREE_TYPE (arg)))
 	{
+	  bool addr_nonzero = false;
+	  bool strict_overflow = false;
+
 	  if (TREE_CODE (arg) == SSA_NAME
 	      && param_type
 	      && get_ptr_nonnull (arg))
+	    addr_nonzero = true;
+	  else if (tree_expr_nonzero_warnv_p (arg, &strict_overflow))
+	    {
+	      if (!strict_overflow)
+		addr_nonzero = true;
+	    }
+
+	  if (addr_nonzero)
 	    {
 	      jfunc->vr_known = true;
 	      jfunc->m_vr.type = VR_ANTI_RANGE;
diff --git a/gcc/testsuite/gcc.dg/ipa/vrp5.c b/gcc/testsuite/gcc.dg/ipa/vrp5.c
index e69de29..571798d 100644
--- a/gcc/testsuite/gcc.dg/ipa/vrp5.c
+++ b/gcc/testsuite/gcc.dg/ipa/vrp5.c
@@ -0,0 +1,34 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-ipa-cp-details -fdump-tree-vrp1" } */
+
+static __attribute__((noinline, noclone))
+int foo (int *p)
+{
+  if (!p)
+    return 0;
+  *p = 1;
+}
+
+struct st
+{
+  int a;
+  int b;
+};
+
+int arr1[10];
+int a;
+int bar (struct st *s)
+{
+  int arr2[10];
+  int b;
+  if (!s)
+    return 0;
+  foo (&s->a);
+  foo (&a);
+  foo (&b);
+  foo (&arr1[1]);
+  foo (&arr2[1]);
+}
+
+/* { dg-final { scan-ipa-dump "Setting nonnull for 0" "cp" } } */
+/* { dg-final { scan-tree-dump-times "if" 1 "vrp1" } } */
diff --git a/gcc/testsuite/gcc.dg/ipa/vrp6.c b/gcc/testsuite/gcc.dg/ipa/vrp6.c
index e69de29..971db44 100644
--- a/gcc/testsuite/gcc.dg/ipa/vrp6.c
+++ b/gcc/testsuite/gcc.dg/ipa/vrp6.c
@@ -0,0 +1,34 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-ipa-cp-details -fdump-tree-vrp1" } */
+
+static __attribute__((noinline, noclone))
+int foo (int *p)
+{
+  if (!p)
+    return 0;
+  *p = 1;
+}
+
+struct st
+{
+  int a;
+  int b;
+};
+
+struct st s2;
+int a;
+int bar (struct st *s)
+{
+  struct st s3;
+  int b;
+  if (!s)
+    return 0;
+  foo (&s->a);
+  foo (&s2.a);
+  foo (&s3.a);
+  foo (&a);
+  foo (&b);
+}
+
+/* { dg-final { scan-ipa-dump "Setting nonnull for 0" "cp" } } */
+/* { dg-final { scan-tree-dump-times "if" 1 "vrp1" } } */