Refactor compute minus zero checks into a proper HPhase.

src/hydrogen-minus-zero.h

Index: src/hydrogen-minus-zero.h
diff --git a/src/hydrogen-minus-zero.h b/src/hydrogen-minus-zero.h
new file mode 100644
index 0000000000000000000000000000000000000000..d23ec1196b3419cdc06e20aa3e12688979306009
--- /dev/null
+++ b/src/hydrogen-minus-zero.h
@@ -0,0 +1,56 @@
+// Copyright 2013 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_HYDROGEN_MINUS_ZERO_H_
+#define V8_HYDROGEN_MINUS_ZERO_H_
+
+#include "hydrogen.h"
+
+namespace v8 {
+namespace internal {
+
+
+class HComputeMinusZeroChecksPhase : public HPhase {
+ public:
+  explicit HComputeMinusZeroChecksPhase(HGraph* graph)
+      : HPhase("H_Compute minus zero checks", graph),
+        visited_(graph->GetMaximumValueID(), zone()) { }
+
+  void Run();
+
+ private:
+  void PropagateMinusZeroChecks(HValue* value);
+
+  BitVector visited_;
+
+  DISALLOW_COPY_AND_ASSIGN(HComputeMinusZeroChecksPhase);
+};
+
+
+} }  // namespace v8::internal
+
+#endif  // V8_HYDROGEN_MINUS_ZERO_H_