re PR tree-optimization/53465 (wrong code with -O1 -ftree-vrp)

	PR tree-optimization/53465
	* tree-vrp.c (extract_range_from_cond_expr): First copy_value_range
	vr0 into *vr, then vrp_meet that.
	(vrp_meet): If one vr type is VR_UNDEFINED, ensure the result doesn't
	have any equivalences.
	(vrp_visit_phi_node): Call copy_value_range instead of vrp_meet the
	first time.

	* gcc.c-torture/execute/pr53465.c: New test.

From-SVN: r187827

4 files changed, 60 insertions, 6 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8246ae9..aec62a0 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,4 +1,14 @@
-2012-05-24  Jim MacArthur<jim.macarthur@arm.com>
+2012-05-24  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/53465
+	* tree-vrp.c (extract_range_from_cond_expr): First copy_value_range
+	vr0 into *vr, then vrp_meet that.
+	(vrp_meet): If one vr type is VR_UNDEFINED, ensure the result doesn't
+	have any equivalences.
+	(vrp_visit_phi_node): Call copy_value_range instead of vrp_meet the
+	first time.
+
+2012-05-24  Jim MacArthur  <jim.macarthur@arm.com>
 
 	* recog.c (reg_fits_class_p): Check both regno and regno + offset are
 	hard registers.
@@ -2897,7 +2907,7 @@
 	is enabled.
 	(movdi_vfp_cortexa8): Likewise.
 
-2012-04-30  Ian Bolton	<ian.bolton@arm.com>
+2012-04-30  Ian Bolton  <ian.bolton@arm.com>
 	    Sameera Deshpande  <sameera.deshpande@arm.com>
 	    Greta Yorsh	 <greta.yorsh@arm.com>
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f337a29..3ee4008 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2012-05-24  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/53465
+	* gcc.c-torture/execute/pr53465.c: New test.
+
 2012-05-23  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/51055
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr53465.c b/gcc/testsuite/gcc.c-torture/execute/pr53465.c
new file mode 100644
index 0000000..6a31719
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr53465.c
@@ -0,0 +1,30 @@
+/* PR tree-optimization/53465 */
+
+extern void abort ();
+
+static const int a[] = { 1, 2 };
+
+void
+foo (const int *x, int y)
+{
+  int i;
+  int b = 0;
+  int c;
+  for (i = 0; i < y; i++)
+    {
+      int d = x[i];
+      if (d == 0)
+	break;
+      if (b && d <= c)
+	abort ();
+      c = d;
+      b = 1;
+    }
+}
+
+int
+main ()
+{
+  foo (a, 2);
+  return 0;
+}
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 4dc942c..2c1bcad 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -3282,8 +3282,8 @@ extract_range_from_cond_expr (value_range_t *vr, gimple stmt)
     set_value_range_to_varying (&vr1);
 
   /* The resulting value range is the union of the operand ranges */
-  vrp_meet (&vr0, &vr1);
   copy_value_range (vr, &vr0);
+  vrp_meet (vr, &vr1);
 }
 
 
@@ -6888,13 +6888,17 @@ vrp_meet (value_range_t *vr0, value_range_t *vr1)
 {
   if (vr0->type == VR_UNDEFINED)
     {
-      copy_value_range (vr0, vr1);
+      /* Drop equivalences.  See PR53465.  */
+      set_value_range (vr0, vr1->type, vr1->min, vr1->max, NULL);
       return;
     }
 
   if (vr1->type == VR_UNDEFINED)
     {
-      /* Nothing to do.  VR0 already has the resulting range.  */
+      /* VR0 already has the resulting range, just drop equivalences.
+	 See PR53465.  */
+      if (vr0->equiv)
+	bitmap_clear (vr0->equiv);
       return;
     }
 
@@ -7036,6 +7040,7 @@ vrp_visit_phi_node (gimple phi)
   tree lhs = PHI_RESULT (phi);
   value_range_t *lhs_vr = get_value_range (lhs);
   value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
+  bool first = true;
   int edges, old_edges;
   struct loop *l;
 
@@ -7092,7 +7097,11 @@ vrp_visit_phi_node (gimple phi)
 	      fprintf (dump_file, "\n");
 	    }
 
-	  vrp_meet (&vr_result, &vr_arg);
+	  if (first)
+	    copy_value_range (&vr_result, &vr_arg);
+	  else
+	    vrp_meet (&vr_result, &vr_arg);
+	  first = false;
 
 	  if (vr_result.type == VR_VARYING)
 	    break;