From: Richard Biener <rguenther@suse.de>
Date: Mon, 20 Aug 2018 14:01:05 +0000 (+0000)
Subject: re PR c++/78655 (gcc doesn't exploit the fact that the result of pointer addition... 
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=4864297f7858617a5fe406d3651a46446b41db7a;p=gcc.git

re PR c++/78655 (gcc doesn't exploit the fact that the result of pointer addition can not be nullptr)

2018-08-20  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/78655
	* tree-vrp.c (extract_range_from_binary_expr_1): Make
	pointer + offset nonnull if either operand is nonnull work.

	* gcc.dg/tree-ssa/evrp11.c: New testcase.

From-SVN: r263662
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3dbcd1c82db..6cf673c7382 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-08-20  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/78655
+	* tree-vrp.c (extract_range_from_binary_expr_1): Make
+	pointer + offset nonnull if either operand is nonnull work.
+
 2018-08-20  Tom de Vries  <tdevries@suse.de>
 
 	* dwarf2out.c (add_scalar_info): Don't add reference to existing die
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index e89f4a4c093..1eaec9008da 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-08-20  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/78655
+	* gcc.dg/tree-ssa/evrp11.c: New testcase.
+
 2018-08-18  Iain Sandoe  <iain@sandoe.co.uk>
 
 	* gcc.dg/debug/dwarf2/pr80263.c: Suppress pubtypes output
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/evrp11.c b/gcc/testsuite/gcc.dg/tree-ssa/evrp11.c
new file mode 100644
index 00000000000..f1373bd8683
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/evrp11.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-evrp" } */
+
+extern void link_error ();
+
+void foo (int *x)
+{
+  int *p = x + 1;
+  if (p == 0)
+    link_error ();
+}
+
+void bar (char *x, int a)
+{
+  if (a != 0)
+    {
+      char *p = x + a;
+      if (p == 0)
+	link_error ();
+    }
+}
+
+/* { dg-final { scan-tree-dump-not "link_error" "evrp" } }  */
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index d553a254878..2ddb0c2c197 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -1437,6 +1437,7 @@ extract_range_from_binary_expr_1 (value_range *vr,
       && code != PLUS_EXPR
       && code != MINUS_EXPR
       && code != RSHIFT_EXPR
+      && code != POINTER_PLUS_EXPR
       && (vr0.type == VR_VARYING
 	  || vr1.type == VR_VARYING
 	  || vr0.type != vr1.type
@@ -1467,7 +1468,11 @@ extract_range_from_binary_expr_1 (value_range *vr,
 	{
 	  /* For pointer types, we are really only interested in asserting
 	     whether the expression evaluates to non-NULL.  */
-	  if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
+	  if (range_is_nonnull (&vr0)
+	      || range_is_nonnull (&vr1)
+	      || (vr1.type == VR_RANGE
+		  && !symbolic_range_p (&vr1)
+		  && !range_includes_zero_p (vr1.min, vr1.max)))
 	    set_value_range_to_nonnull (vr, expr_type);
 	  else if (range_is_null (&vr0) && range_is_null (&vr1))
 	    set_value_range_to_null (vr, expr_type);