[PATCH] Fix PR66863

[Richard Biener]

The following fixes PR66863.

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

Richard.

2015-07-14  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/66863
        * tree-vrp.c (register_edge_assert_for_2): Properly restrict
        what we record for conversion use stmt lhs inequalities.

        * gcc.dg/torture/pr66863.c: New testcase.

Index: gcc/tree-vrp.c
===================================================================
--- gcc/tree-vrp.c      (revision 225761)
+++ gcc/tree-vrp.c      (working copy)
@@ -5381,7 +5381,17 @@ register_edge_assert_for_2 (tree name, e
              cst = int_const_binop (code, val, cst);
            }
          else if (CONVERT_EXPR_CODE_P (code))
-           cst = fold_convert (TREE_TYPE (name2), val);
+           {
+             /* For truncating conversions require that the constant
+                fits in the truncated type if we are going to 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)))
+               continue;
+             cst = fold_convert (TREE_TYPE (name2), val);
+           }
          else
            continue;
 
Index: gcc/testsuite/gcc.dg/torture/pr66863.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr66863.c      (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr66863.c      (working copy)
@@ -0,0 +1,25 @@
+/* { dg-do run } */
+
+int a, b;
+
+int
+fn1 (int p1)
+{
+  if (p1 < -2147483647) 
+    return 0;
+  else 
+    return 1;
+}
+
+int
+fn2 (int p1, short p2)
+{
+  return p2 ? p1 % p2 : 0; 
+}
+
+int
+main ()
+{
+  b = fn2 (fn1 (a), a);
+  return 0;
+}