[PATCH] Fix PR66894

[Richard Biener]

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2015-07-16  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/66894
        * tree-vrp.c (register_edge_assert_for_2): Fix bad assumption
        about deriving NE_EXPR from truncated values.

        * gcc.dg/torture/pr66894.c: New testcase.

Index: gcc/tree-vrp.c
===================================================================
--- gcc/tree-vrp.c      (revision 225860)
+++ gcc/tree-vrp.c      (working copy)
@@ -5382,13 +5382,11 @@ register_edge_assert_for_2 (tree name, e
            }
          else if (CONVERT_EXPR_CODE_P (code))
            {
-             /* For truncating conversions require that the constant
-                fits in the truncated type if we are going to record
+             /* For truncating conversions we cannot record
                 an inequality.  */
              if (comp_code == NE_EXPR
                  && (TYPE_PRECISION (TREE_TYPE (name2))
-                     < TYPE_PRECISION (TREE_TYPE (name)))
-                 && ! int_fits_type_p (val, TREE_TYPE (name2)))
+                     < TYPE_PRECISION (TREE_TYPE (name))))
                continue;
              cst = fold_convert (TREE_TYPE (name2), val);
            }
Index: gcc/testsuite/gcc.dg/torture/pr66894.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr66894.c      (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr66894.c      (working copy)
@@ -0,0 +1,21 @@
+/* { dg-do run } */
+
+short a, b;
+
+int
+main ()
+{
+  for (; a != 1; a += 3)
+    {
+      int c = 0;
+      for (; c < 2; c++)
+       if (a)
+         {
+           char d = a;
+           b = d ? 1 / d : 0; 
+         }
+       else
+         break;
+    }
+  return 0;
+}