1 files changed, 28 insertions, 4 deletions
diff --git a/rpython/jit/metainterp/optimizeopt/intutils.py b/rpython/jit/metainterp/optimizeopt/intutils.py
index 9f2ced0f00..49e2b3498e 100644
--- a/rpython/jit/metainterp/optimizeopt/intutils.py
+++ b/rpython/jit/metainterp/optimizeopt/intutils.py
@@ -26,6 +26,18 @@ def next_pow2_m1(n):
     return n
 
 
+def upper_bound_or_xor(upper1, upper2):
+    pow2 = next_pow2_m1(upper1 | upper2)
+    try:
+        # addition gives an ok (but not tight) upper bound of | and ^ (for
+        # known non-negative numbers)
+        add = ovfcheck(upper1 + upper2)
+    except OverflowError:
+        return pow2
+    else:
+        return min(pow2, add)
+
+
 class IntBound(AbstractInfo):
     _attrs_ = ('has_upper', 'has_lower', 'upper', 'lower')
 
@@ -302,11 +314,23 @@ class IntBound(AbstractInfo):
         r = IntUnbounded()
         if self.known_nonnegative() and \
                 other.known_nonnegative():
+            r.make_ge_const(0)
             if self.has_upper and other.has_upper:
-                mostsignificant = self.upper | other.upper
-                r.intersect(IntBound(0, next_pow2_m1(mostsignificant)))
-            else:
-                r.make_ge_const(0)
+                r.make_le_const(upper_bound_or_xor(self.upper, other.upper))
+            if self.has_lower and other.has_lower:
+                # max of the two lower bounds gives an ok (but not tight) lower
+                # bound of or
+                lower = max(self.lower, other.lower)
+                r.make_ge_const(lower)
+        return r
+
+    def xor_bound(self, other):
+        r = IntUnbounded()
+        if self.known_nonnegative() and \
+                other.known_nonnegative():
+            r.make_ge_const(0)
+            if self.has_upper and other.has_upper:
+                r.make_le_const(upper_bound_or_xor(self.upper, other.upper))
         return r
 
     def invert_bound(self):