------- Comment #14 from rguenth at gcc dot gnu dot org 2009-04-24 16:47
-------
May be worth fixing this simple case without fully fixing PR30318. Like with
Index: tree-vrp.c
===================================================================
--- tree-vrp.c (revision 146590)
+++ tree-vrp.c (working copy)
@@ -2248,6 +2248,22 @@ extract_range_from_binary_expr (value_ra
the same end of each range. */
min = vrp_int_const_binop (code, vr0.min, vr1.min);
max = vrp_int_const_binop (code, vr0.max, vr1.max);
+
+ /* If both additions overflowed the range kind is still correct.
+ This happens regularly with subtracting something in unsigned
+ arithmetic.
+ ??? See PR30318 for all the cases we do not handle. */
+ if (code == PLUS_EXPR
+ && (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
+ && (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
+ {
+ min = build_int_cst_wide (TREE_TYPE (min),
+ TREE_INT_CST_LOW (min),
+ TREE_INT_CST_HIGH (min));
+ max = build_int_cst_wide (TREE_TYPE (max),
+ TREE_INT_CST_LOW (max),
+ TREE_INT_CST_HIGH (max));
+ }
}
else if (code == MULT_EXPR
|| code == TRUNC_DIV_EXPR
I am testing that patch.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39870
