Set nonnull attribute to ptr_info_def based on VRP

Message ID 3b8ae8ba-97e7-7363-fecc-bd0e0f85abcf@linaro.org
State New
Headers show

Commit Message

kugan Oct. 7, 2016, 12:53 a.m.
Hi Richard,

Thanks for the review.

On 09/08/16 18:58, Richard Biener wrote:
> On Tue, Aug 9, 2016 at 12:58 AM, kugan

> <kugan.vivekanandarajah@linaro.org> wrote:

>> Hi Jakub,

>>

>> Thanks for the review.

>>

>> On 08/08/16 16:40, Jakub Jelinek wrote:

>>>

>>> On Mon, Aug 08, 2016 at 01:36:51PM +1000, kugan wrote:

>>>>

>>>> diff --git a/gcc/tree-ssanames.h b/gcc/tree-ssanames.h

>>>> index c81b1a1..6e34433 100644

>>>> --- a/gcc/tree-ssanames.h

>>>> +++ b/gcc/tree-ssanames.h

>>>> @@ -43,6 +43,9 @@ struct GTY(()) ptr_info_def

>>>>       above alignment.  Access only through the same helper functions as

>>>> align

>>>>       above.  */

>>>>    unsigned int misalign;

>>>> +  /* When this pointer is knonw to be nnonnull this would be true

>>>> otherwise

>>>> +     false.  */

>>>> +  bool  nonnull_p;

>>>>  };

>>>

>>>

>>> Why do you need this?  Doesn't the pt.null bit represent that already?

>>

>>

>> It looks like I can use this. As in gcc/tree-ssa-alias.h:

>>

>>   /* Nonzero if the points-to set includes 'nothing', the points-to set

>>      includes memory at address NULL.  */

>>   unsigned int null : 1;

>>

>> But in gcc/tree-ssa-alias.c, ptrs_compare_unequal has the following comment

>> which says:

>>

>> /* ???  We'd like to handle ptr1 != NULL and ptr1 != ptr2

>>      but those require pt.null to be conservatively correct.  */

>>

>> Does that means it can be wrong at times? I haven't looked it in detail yet

>> but if it is, it would be a problem.

>

> Yes, this bit is not correctly computed for all cases (well, it works

> for trivial

> ones but for example misses weaks and maybe some other corner-cases).

>

> Currently there are no consumers of this bit so the incorrectness

> doesn't matter.

>

> I suggest you simply use that bit but set it conservatively from PTA (to true)

> for now and adjust it from VRP only.

>

> I do have some patches for fixinig some of the .nonnull_p issues in PTA but

> they come at a cost of more constraints.


Here is a version of the patch that does this. I have a follow up patch 
to use this in ipa-vrp. I will send it for review once this is OK.

Bootstrapped and regression tested on x86_64-linux-gnu with no new 
regressions. Is this OK for trunk?


Thanks,
Kugan

gcc/ChangeLog:

2016-10-07  Kugan Vivekanandarajah  <kuganv@linaro.org>

	* tree-ssa-alias.c (dump_points_to_solution): Dump non null as it
	  is set to null conservatively.
	* tree-ssa-structalias.c (find_what_var_points_to): Set to null
	  conservatively.
	(pt_solution_singleton_p): Dont check null.
	* tree-ssanames.c (set_ptr_nonnull): New.
	(get_ptr_nonnull): Likewise.
	* tree-vrp.c (vrp_finalize): Set ptr that are nonnull.
	(evrp_dom_walker::before_dom_children): Likewise.
>

> Richard.

>

>>> Also, formatting and spelling:

>>> s/knonw/known/

>>> s/nnon/non/

>>> s/bool  /bool /

>>

>>

>> I will change this.

>>

>> Thanks,

>> Kugan

>>>

>>>

>>>         Jakub

>>>

>>

Patch hide | download patch | download mbox

From 20ef028b2e38e3d91874ba873be10e5dfdac4d05 Mon Sep 17 00:00:00 2001
From: Kugan Vivekanandarajah <kugan.vivekanandarajah@linaro.org>
Date: Fri, 30 Sep 2016 09:00:08 +1000
Subject: [PATCH 3/5] Add nonnull to pointer from VRP

---
 gcc/tree-ssa-alias.c       |  4 ++--
 gcc/tree-ssa-structalias.c |  6 ++++--
 gcc/tree-ssanames.c        | 21 +++++++++++++++++++++
 gcc/tree-ssanames.h        |  2 ++
 gcc/tree-vrp.c             | 44 +++++++++++++++++++++++++++++---------------
 5 files changed, 58 insertions(+), 19 deletions(-)

diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 30de461..ccad68d 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -515,8 +515,8 @@  dump_points_to_solution (FILE *file, struct pt_solution *pt)
   if (pt->ipa_escaped)
     fprintf (file, ", points-to unit escaped");
 
-  if (pt->null)
-    fprintf (file, ", points-to NULL");
+  if (!pt->null)
+    fprintf (file, ", points-to non NULL");
 
   if (pt->vars)
     {
diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c
index be892fd..99b373f8 100644
--- a/gcc/tree-ssa-structalias.c
+++ b/gcc/tree-ssa-structalias.c
@@ -6349,6 +6349,8 @@  find_what_var_points_to (tree fndecl, varinfo_t orig_vi)
 
   *slot = pt = XOBNEW (&final_solutions_obstack, struct pt_solution);
   memset (pt, 0, sizeof (struct pt_solution));
+  /* Conservatively set to NULL from PTA (to true). */
+  pt->null = 1;
 
   /* Translate artificial variables into SSA_NAME_PTR_INFO
      attributes.  */
@@ -6359,7 +6361,7 @@  find_what_var_points_to (tree fndecl, varinfo_t orig_vi)
       if (vi->is_artificial_var)
 	{
 	  if (vi->id == nothing_id)
-	    pt->null = 1;
+	    ;
 	  else if (vi->id == escaped_id)
 	    {
 	      if (in_ipa_mode)
@@ -6569,7 +6571,7 @@  bool
 pt_solution_singleton_p (struct pt_solution *pt, unsigned *uid)
 {
   if (pt->anything || pt->nonlocal || pt->escaped || pt->ipa_escaped
-      || pt->null || pt->vars == NULL
+      || pt->vars == NULL
       || !bitmap_single_bit_set_p (pt->vars))
     return false;
 
diff --git a/gcc/tree-ssanames.c b/gcc/tree-ssanames.c
index 91a8f97..6b6619f 100644
--- a/gcc/tree-ssanames.c
+++ b/gcc/tree-ssanames.c
@@ -374,6 +374,27 @@  get_range_info (const_tree name, wide_int *min, wide_int *max)
   return SSA_NAME_RANGE_TYPE (name);
 }
 
+/* Set nonnull attribute to pointer NAME.  */
+
+void
+set_ptr_nonnull (tree name)
+{
+  gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
+  struct ptr_info_def *pi = get_ptr_info (name);
+  pi->pt.null = 0;
+}
+
+/* Return nonnull attribute of pointer NAME.  */
+bool
+get_ptr_nonnull (const_tree name)
+{
+  gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
+  struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
+  if (pi == NULL)
+    return false;
+  return !pi->pt.null;
+}
+
 /* Change non-zero bits bitmask of NAME.  */
 
 void
diff --git a/gcc/tree-ssanames.h b/gcc/tree-ssanames.h
index 4496e1d..d39cc9d 100644
--- a/gcc/tree-ssanames.h
+++ b/gcc/tree-ssanames.h
@@ -88,6 +88,8 @@  extern void set_ptr_info_alignment (struct ptr_info_def *, unsigned int,
 extern void adjust_ptr_info_misalignment (struct ptr_info_def *,
 					  unsigned int);
 extern struct ptr_info_def *get_ptr_info (tree);
+extern void set_ptr_nonnull (tree);
+extern bool get_ptr_nonnull (const_tree);
 
 extern tree copy_ssa_name_fn (struct function *, tree, gimple *);
 extern void duplicate_ssa_name_ptr_info (tree, struct ptr_info_def *);
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 0892709..80b7302 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -10593,18 +10593,24 @@  vrp_finalize (bool warn_array_bounds_p)
       {
 	tree name = ssa_name (i);
 
-      if (!name
-	  || POINTER_TYPE_P (TREE_TYPE (name))
-	  || (vr_value[i]->type == VR_VARYING)
-	  || (vr_value[i]->type == VR_UNDEFINED))
-	continue;
+	if (!name
+	    || (vr_value[i]->type == VR_VARYING)
+	    || (vr_value[i]->type == VR_UNDEFINED)
+	    || (TREE_CODE (vr_value[i]->min) != INTEGER_CST)
+	    || (TREE_CODE (vr_value[i]->max) != INTEGER_CST))
+	  continue;
 
-      if ((TREE_CODE (vr_value[i]->min) == INTEGER_CST)
-	  && (TREE_CODE (vr_value[i]->max) == INTEGER_CST)
-	  && (vr_value[i]->type == VR_RANGE
-	      || vr_value[i]->type == VR_ANTI_RANGE))
-	set_range_info (name, vr_value[i]->type, vr_value[i]->min,
-			vr_value[i]->max);
+	if (POINTER_TYPE_P (TREE_TYPE (name))
+	    && ((vr_value[i]->type == VR_RANGE
+		 && range_includes_zero_p (vr_value[i]->min,
+					   vr_value[i]->max) == 0)
+		|| (vr_value[i]->type == VR_ANTI_RANGE
+		    && range_includes_zero_p (vr_value[i]->min,
+					      vr_value[i]->max) == 1)))
+	  set_ptr_nonnull (name);
+	else if (!POINTER_TYPE_P (TREE_TYPE (name)))
+	  set_range_info (name, vr_value[i]->type, vr_value[i]->min,
+			  vr_value[i]->max);
       }
 
   substitute_and_fold (op_with_constant_singleton_value_range,
@@ -10808,17 +10814,25 @@  evrp_dom_walker::before_dom_children (basic_block bb)
 	  def_operand_p def_p = SINGLE_SSA_DEF_OPERAND (stmt, SSA_OP_DEF);
 	  /* Set the SSA with the value range.  */
 	  if (def_p
-	      && TREE_CODE (DEF_FROM_PTR (def_p)) == SSA_NAME
-	      && INTEGRAL_TYPE_P (TREE_TYPE (DEF_FROM_PTR (def_p))))
+	      && TREE_CODE (DEF_FROM_PTR (def_p)) == SSA_NAME)
 	    {
 	      tree def = DEF_FROM_PTR (def_p);
 	      value_range *vr = get_value_range (def);
 
-	      if ((vr->type == VR_RANGE
-		   || vr->type == VR_ANTI_RANGE)
+	      if (INTEGRAL_TYPE_P (TREE_TYPE (DEF_FROM_PTR (def_p)))
+		  && (vr->type == VR_RANGE
+		      || vr->type == VR_ANTI_RANGE)
 		  && (TREE_CODE (vr->min) == INTEGER_CST)
 		  && (TREE_CODE (vr->max) == INTEGER_CST))
 		set_range_info (def, vr->type, vr->min, vr->max);
+	      else if (POINTER_TYPE_P (TREE_TYPE (DEF_FROM_PTR (def_p)))
+		       && ((vr->type == VR_RANGE
+			    && range_includes_zero_p (vr->min,
+						      vr->max) == 0)
+			   || (vr->type == VR_ANTI_RANGE
+			       && range_includes_zero_p (vr->min,
+							 vr->max) == 1)))
+		set_ptr_nonnull (def);
 	    }
 	}
       else
-- 
2.7.4