Use bit fields to calculate compare stub minor key

Review URL: http://codereview.chromium.org/1081010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4208 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/codegen-arm.cc

@@ -7159,11 +7159,13 @@ const char* CompareStub::GetName() {
 
 
 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);
 }
 
 

src/codegen.h

@@ -361,6 +361,11 @@ class CompareStub: public CodeStub {
   // stubs.
   bool never_nan_nan_;
 
+  // Encoding of the minor key CCCCCCCCCCCCCCNS.
+  class StrictField: public BitField<bool, 0, 1> {};
+  class NeverNanNanField: public BitField<bool, 1, 1> {};
+  class ConditionField: public BitField<int, 2, 14> {};
+
   Major MajorKey() { return Compare; }
 
   int MinorKey();

src/ia32/codegen-ia32.cc

@@ -11534,11 +11534,13 @@ const char* CompareStub::GetName() {
 
 
 int CompareStub::MinorKey() {
-  // Encode the three parameters in a unique 16 bit value.
+  // 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_) < (1 << 14));
-  int nnn_value = (never_nan_nan_ ? 2 : 0);
-  if (cc_ != equal) nnn_value = 0;  // Avoid duplicate stubs.
-  return (static_cast<unsigned>(cc_) << 2) | nnn_value | (strict_ ? 1 : 0);
+  return ConditionField::encode(static_cast<unsigned>(cc_))
+         | StrictField::encode(strict_)
+         | NeverNanNanField::encode(cc_ == equal ? never_nan_nan_ : false);
 }
 
 

src/x64/codegen-x64.cc

@@ -9105,11 +9105,13 @@ Handle<Code> GetBinaryOpStub(int key, BinaryOpIC::TypeInfo type_info) {
 
 
 int CompareStub::MinorKey() {
-  // Encode the three parameters in a unique 16 bit value.
+  // 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_) < (1 << 14));
-  int nnn_value = (never_nan_nan_ ? 2 : 0);
-  if (cc_ != equal) nnn_value = 0;  // Avoid duplicate stubs.
-  return (static_cast<unsigned>(cc_) << 2) | nnn_value | (strict_ ? 1 : 0);
+  return ConditionField::encode(static_cast<unsigned>(cc_))
+         | StrictField::encode(strict_)
+         | NeverNanNanField::encode(cc_ == equal ? never_nan_nan_ : false);
 }