[PATCH] Fix VRP ICE on x >> cst1; if (x cmp cst2) (PR tree-optimization/53058, take 2)

[Jakub Jelinek]

On Tue, Apr 24, 2012 at 08:05:35AM +0200, Richard Guenther wrote:
> On Tue, Apr 24, 2012 at 1:01 AM, Jakub Jelinek <ja...@redhat.com> wrote:
> I don't like using TYPE_MAX_VALUE in VRP - at least please use vrp_val_max.
> For enums this can be not what you expect(?)
> 
> Please consider adding a double_int_max_value (unsigned prec, bool sign)
> and double_int_min_value.

So like this instead?

2012-04-24  Jakub Jelinek  <ja...@redhat.com>

        PR tree-optimization/53058
        * double-int.h (double_int_max_value, double_int_min_value): New
        functions.
        * tree-vrp.c (register_edge_assert_for_2): Compare mask
        for LE_EXPR or GT_EXPR with double_int_max_value
        instead of double_int_mask.

        * gcc.c-torture/compile/pr53058.c: New test.

--- gcc/double-int.h.jj 2012-04-19 11:09:13.000000000 +0200
+++ gcc/double-int.h    2012-04-24 08:42:42.655756406 +0200
@@ -1,5 +1,5 @@
 /* Operations with long integers.
-   Copyright (C) 2006, 2007, 2008, 2010 Free Software Foundation, Inc.
+   Copyright (C) 2006, 2007, 2008, 2010, 2012 Free Software Foundation, Inc.
 
 This file is part of GCC.
 
@@ -280,6 +280,26 @@ double_int_equal_p (double_int cst1, dou
   return cst1.low == cst2.low && cst1.high == cst2.high;
 }
 
+/* Returns a maximum value for signed or unsigned integer
+   of precision PREC.  */
+
+static inline double_int
+double_int_max_value (unsigned int prec, bool uns)
+{
+  return double_int_mask (prec - (uns ? 0 : 1));
+}
+
+/* Returns a minimum value for signed or unsigned integer
+   of precision PREC.  */
+
+static inline double_int
+double_int_min_value (unsigned int prec, bool uns)
+{
+  if (uns)
+    return double_int_zero;
+  return double_int_lshift (double_int_one, prec - 1, prec, false);
+}
+
 
 /* Legacy interface with decomposed high/low parts.  */
 
--- gcc/tree-vrp.c.jj   2012-04-23 11:11:21.000000000 +0200
+++ gcc/tree-vrp.c      2012-04-24 09:06:29.116624564 +0200
@@ -4565,6 +4565,7 @@ register_edge_assert_for_2 (tree name, e
              && INTEGRAL_TYPE_P (TREE_TYPE (name2))
              && IN_RANGE (tree_low_cst (cst2, 1), 1, prec - 1)
              && prec <= 2 * HOST_BITS_PER_WIDE_INT
+             && prec == GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (val)))
              && live_on_edge (e, name2)
              && !has_single_use (name2))
            {
@@ -4598,8 +4599,10 @@ register_edge_assert_for_2 (tree name, e
            new_val = val2;
          else
            {
+             double_int maxval
+               = double_int_max_value (prec, TYPE_UNSIGNED (TREE_TYPE (val)));
              mask = double_int_ior (tree_to_double_int (val2), mask);
-             if (double_int_minus_one_p (double_int_sext (mask, prec)))
+             if (double_int_equal_p (mask, maxval))
                new_val = NULL_TREE;
              else
                new_val = double_int_to_tree (TREE_TYPE (val2), mask);
--- gcc/testsuite/gcc.c-torture/compile/pr53058.c.jj    2012-04-23 
15:53:41.489982650 +0200
+++ gcc/testsuite/gcc.c-torture/compile/pr53058.c       2012-04-23 
15:53:13.000000000 +0200
@@ -0,0 +1,12 @@
+/* PR tree-optimization/53058 */
+
+int a, b, c;
+
+void
+foo ()
+{
+  c = b >> 16;
+  if (c > 32767)
+    c = 0;
+  a = b;
+}

        Jakub