Merge (x & y) == 0 pattern to emit a single test instruction.

runtime/vm/flow_graph_optimizer.cc

 // Copyright (c) 2013, 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_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_compiler.h"
@@ skipping 4031 matching lines @@
     case Token::kGT: return (result > 0);
     case Token::kLTE: return (result <= 0);
     case Token::kGTE: return (result >= 0);
     default:
       UNREACHABLE();
       return false;
   }
 }
 
 
+void ConstantPropagator::VisitTestSmi(TestSmiInstr* instr) {
+  const Object& left = instr->left()->definition()->constant_value();
+  const Object& right = instr->right()->definition()->constant_value();
+  if (IsNonConstant(left) || IsNonConstant(right)) {
+    SetValue(instr, non_constant_);
+  } else if (IsConstant(left) && IsConstant(right)) {
+    if (left.IsInteger() && right.IsInteger()) {
+      const bool result = CompareIntegers(
+          instr->kind(),
+          Integer::Handle(Integer::Cast(left).BitOp(Token::kBIT_AND,
+                                                    Integer::Cast(right))),
+          Smi::Handle(Smi::New(0)));
+      SetValue(instr, result ? Bool::True() : Bool::False());
+    } else {
+      SetValue(instr, non_constant_);
+    }
+  }
+}
+
+
 void ConstantPropagator::VisitEqualityCompare(EqualityCompareInstr* instr) {
   const Object& left = instr->left()->definition()->constant_value();
   const Object& right = instr->right()->definition()->constant_value();
   if (IsNonConstant(left) || IsNonConstant(right)) {
     SetValue(instr, non_constant_);
   } else if (IsConstant(left) && IsConstant(right)) {
     if (left.IsInteger() && right.IsInteger()) {
       const bool result = CompareIntegers(instr->kind(),
                                           Integer::Cast(left),
                                           Integer::Cast(right));
@@ skipping 954 matching lines @@
   if (changed) {
     // We may have changed the block order and the dominator tree.
     flow_graph->DiscoverBlocks();
     GrowableArray<BitVector*> dominance_frontier;
     flow_graph->ComputeDominators(&dominance_frontier);
   }
 }
 
 
 }  // namespace dart