[PATCH] Fix PR83418

[Richard Biener]

IVOPTs (at least) leaves unfolded stmts in the IL and VRP overzealously
asserts they cannot happen.

Bootstrap and regtest running on x86_64-unknown-linux-gnu.

Richard.

2017-12-14  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/83418
        * vr-values.c (vr_values::extract_range_for_var_from_comparison_expr):
        Instead of asserting we don't get unfolded comparisons deal with
        them.

        * gcc.dg/torture/pr83418.c: New testcase.

Index: gcc/vr-values.c
===================================================================
--- gcc/vr-values.c     (revision 255622)
+++ gcc/vr-values.c     (working copy)
@@ -445,11 +445,12 @@ vr_values::extract_range_for_var_from_co
   tree  min, max, type;
   value_range *limit_vr;
   type = TREE_TYPE (var);
-  gcc_assert (limit != var);
 
   /* For pointer arithmetic, we only keep track of pointer equality
-     and inequality.  */
-  if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
+     and inequality.  If we arrive here with unfolded conditions like
+     _1 > _1 do not derive anything.  */
+  if ((POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
+      || limit == var)
     {
       set_value_range_to_varying (vr_p);
       return;
Index: gcc/testsuite/gcc.dg/torture/pr83418.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr83418.c      (nonexistent)
+++ gcc/testsuite/gcc.dg/torture/pr83418.c      (working copy)
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+
+void
+yj (int j4)
+{
+  int t3;
+
+  for (t3 = 0; t3 < 6; ++t3)
+    {
+      short int v4 = t3;
+
+      if (v4 == j4 || v4 > t3)
+       for (;;)
+         {
+         }
+    }
+}