From ef2e46d1cc4b2e97ac85458811b722af3dcc6b4a Mon Sep 17 00:00:00 2001
From: "sgjesse@chromium.org"
 <sgjesse@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Mon, 22 Mar 2010 14:31:28 +0000
Subject: [PATCH] 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   | 12 +++++++-----
 src/codegen.h            |  5 +++++
 src/ia32/codegen-ia32.cc | 10 ++++++----
 src/x64/codegen-x64.cc   | 10 ++++++----
 4 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/src/arm/codegen-arm.cc b/src/arm/codegen-arm.cc
index d3e98a3..888138a 100644
--- a/src/arm/codegen-arm.cc
+++ b/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);
 }
 
 
diff --git a/src/codegen.h b/src/codegen.h
index 40ed6ce..adab93a 100644
--- a/src/codegen.h
+++ b/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();
diff --git a/src/ia32/codegen-ia32.cc b/src/ia32/codegen-ia32.cc
index 67c9cc1..3c7f1eb 100644
--- a/src/ia32/codegen-ia32.cc
+++ b/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);
 }
 
 
diff --git a/src/x64/codegen-x64.cc b/src/x64/codegen-x64.cc
index a6b0ffc..5956228 100644
--- a/src/x64/codegen-x64.cc
+++ b/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);
 }
 
 
-- 
2.7.4