Use bit fields to calculate compare stub minor key

src/arm/codegen-arm.cc

Index: src/arm/codegen-arm.cc
===================================================================
--- src/arm/codegen-arm.cc	(revision 4200)
+++ src/arm/codegen-arm.cc	(working copy)
@@ -7159,11 +7159,14 @@
 
 
 int CompareStub::MinorKey() {
-  // Encode the three parameters in a unique 16 bit value.
-  ASSERT((static_cast<unsigned>(cc_) >> 26) < (1 << 16));
-  int nnn_value = (never_nan_nan_ ? 2 : 0);
-  if (cc_ != eq) nnn_value = 0;  // Avoid duplicate stubs.
-  return (static_cast<unsigned>(cc_) >> 26) | nnn_value | (strict_ ? 1 : 0);
+  // Encode the three parameters in a unique 16 bit value. To avoid duplicate
+  // stubs the never NaN NaN condition is only taken into account if the
+  // condition is equals.
+  ASSERT((static_cast<unsigned>(cc_) >> 28) < (1 << 14));
+  return ConditionField::encode(static_cast<unsigned>(cc_) >> 28)
+         | StrictField::encode(strict_)
+         | NeverNanNanField::encode(cc_ == eq ? never_nan_nan_ : false);
+
 }