Improve bitwise OR, AND ranges by using the same approximation we use for XOR.

runtime/vm/flow_graph_range_analysis.cc

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph_range_analysis.h"
 
 #include "vm/bit_vector.h"
 #include "vm/il_printer.h"
 
 namespace dart {
@@ skipping 2405 matching lines @@
     *result_max = Range::ConstantMax(right_range);
     return;
   }
 
   if (Range::ConstantMin(left_range).ConstantValue() >= 0) {
     *result_min = RangeBoundary::FromConstant(0);
     *result_max = Range::ConstantMax(left_range);
     return;
   }
 
-  *result_min = RangeBoundary::MinConstant(RangeBoundary::kRangeBoundaryInt64);
-  *result_max = RangeBoundary::MaxConstant(RangeBoundary::kRangeBoundaryInt64);
+  Xor(left_range, right_range, result_min, result_max);

[Florian Schneider, 2014/12/10 15:55:14]

Maybe this should be renamed to BitOp because the approximation is not specific
to xor.

 }
 
 
 static int BitSize(const Range* range) {
   const int64_t min = Range::ConstantMin(range).ConstantValue();
   const int64_t max = Range::ConstantMax(range).ConstantValue();
   return Utils::Maximum(Utils::BitLength(min), Utils::BitLength(max));
 }
 
 
@@ skipping 186 matching lines @@
 
     case Token::kBIT_AND:
       Range::And(left_range, right_range, &min, &max);
       break;
 
     case Token::kBIT_XOR:
       Range::Xor(left_range, right_range, &min, &max);
       break;
 
     case Token::kBIT_OR:
-      *result = Range::Full(RangeBoundary::kRangeBoundaryInt64);
-      return;
+      Range::Xor(left_range, right_range, &min, &max);
+      break;
 
     default:
       *result = Range(RangeBoundary::NegativeInfinity(),
                       RangeBoundary::PositiveInfinity());
       return;
   }
 
   ASSERT(!min.IsUnknown() && !max.IsUnknown());
 
   *result = Range(min, max);
@@ skipping 499 matching lines @@
     }
   } while (CanonicalizeMaxBoundary(&max) ||
            CanonicalizeMinBoundary(&canonical_length));
 
   // Failed to prove that maximum is bounded with array length.
   return false;
 }
 
 
 }  // namespace dart