From 37567c42dabf184a5bedd44c3a757021bbab6348 Mon Sep 17 00:00:00 2001
From: "sandholm@chromium.org"
 <sandholm@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Wed, 22 Dec 2010 13:19:25 +0000
Subject: [PATCH] Introduce NUMBER_IS_FINITE macro to avoid ToNumber()
 conversion. Review URL: http://codereview.chromium.org/5977006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6111 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/date.js            |  2 +-
 src/json.js            | 15 +++++----------
 src/macros.py          |  1 +
 src/mirror-debugger.js |  2 +-
 src/string.js          |  2 +-
 5 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/src/date.js b/src/date.js
index bc70327..9eb607c 100644
--- a/src/date.js
+++ b/src/date.js
@@ -1000,7 +1000,7 @@ function DateToISOString() {
 function DateToJSON(key) {
   var o = ToObject(this);
   var tv = DefaultNumber(o);
-  if (IS_NUMBER(tv) && !$isFinite(tv)) { 
+  if (IS_NUMBER(tv) && !NUMBER_IS_FINITE(tv)) { 
     return null; 
   }
   return o.toISOString();
diff --git a/src/json.js b/src/json.js
index 89009a9..0034176 100644
--- a/src/json.js
+++ b/src/json.js
@@ -27,11 +27,6 @@
 
 var $JSON = global.JSON;
 
-function ParseJSONUnfiltered(text) {
-  var s = $String(text);
-  return %ParseJson(s);
-}
-
 function Revive(holder, name, reviver) {
   var val = holder[name];
   if (IS_OBJECT(val)) {
@@ -58,7 +53,7 @@ function Revive(holder, name, reviver) {
 }
 
 function JSONParse(text, reviver) {
-  var unfiltered = ParseJSONUnfiltered(text);
+  var unfiltered = %ParseJson(TO_STRING_INLINE(text));
   if (IS_FUNCTION(reviver)) {
     return Revive({'': unfiltered}, '', reviver);
   } else {
@@ -158,7 +153,7 @@ function JSONSerialize(key, holder, replacer, stack, indent, gap) {
   if (IS_STRING(value)) {
     return %QuoteJSONString(value);
   } else if (IS_NUMBER(value)) {
-    return $isFinite(value) ? $String(value) : "null";
+    return NUMBER_IS_FINITE(value) ? $String(value) : "null";
   } else if (IS_BOOLEAN(value)) {
     return value ? "true" : "false";
   } else if (IS_NULL(value)) {
@@ -169,7 +164,7 @@ function JSONSerialize(key, holder, replacer, stack, indent, gap) {
       return SerializeArray(value, replacer, stack, indent, gap);
     } else if (IS_NUMBER_WRAPPER(value)) {
       value = ToNumber(value);
-      return $isFinite(value) ? ToString(value) : "null";
+      return NUMBER_IS_FINITE(value) ? ToString(value) : "null";
     } else if (IS_STRING_WRAPPER(value)) {
       return %QuoteJSONString(ToString(value));
     } else if (IS_BOOLEAN_WRAPPER(value)) {
@@ -244,7 +239,7 @@ function BasicJSONSerialize(key, holder, stack, builder) {
   if (IS_STRING(value)) {
     builder.push(%QuoteJSONString(value));
   } else if (IS_NUMBER(value)) {
-    builder.push(($isFinite(value) ? %_NumberToString(value) : "null"));
+    builder.push(NUMBER_IS_FINITE(value) ? %_NumberToString(value) : "null");
   } else if (IS_BOOLEAN(value)) {
     builder.push(value ? "true" : "false");
   } else if (IS_NULL(value)) {
@@ -254,7 +249,7 @@ function BasicJSONSerialize(key, holder, stack, builder) {
     // Unwrap value if necessary
     if (IS_NUMBER_WRAPPER(value)) {
       value = ToNumber(value);
-      builder.push(($isFinite(value) ? %_NumberToString(value) : "null"));
+      builder.push(NUMBER_IS_FINITE(value) ? %_NumberToString(value) : "null");
     } else if (IS_STRING_WRAPPER(value)) {
       builder.push(%QuoteJSONString(ToString(value)));
     } else if (IS_BOOLEAN_WRAPPER(value)) {
diff --git a/src/macros.py b/src/macros.py
index 6d66def..01512e4 100644
--- a/src/macros.py
+++ b/src/macros.py
@@ -120,6 +120,7 @@ macro IS_SPEC_OBJECT(arg) = (%_IsSpecObject(arg));
 
 # Inline macros. Use %IS_VAR to make sure arg is evaluated only once.
 macro NUMBER_IS_NAN(arg) = (!%_IsSmi(%IS_VAR(arg)) && !(arg == arg));
+macro NUMBER_IS_FINITE(arg) = (%_IsSmi(%IS_VAR(arg)) || arg - arg == 0);
 macro TO_INTEGER(arg) = (%_IsSmi(%IS_VAR(arg)) ? arg : %NumberToInteger(ToNumber(arg)));
 macro TO_INTEGER_MAP_MINUS_ZERO(arg) = (%_IsSmi(%IS_VAR(arg)) ? arg : %NumberToIntegerMapMinusZero(ToNumber(arg)));
 macro TO_INT32(arg) = (%_IsSmi(%IS_VAR(arg)) ? arg : (arg >> 0));
diff --git a/src/mirror-debugger.js b/src/mirror-debugger.js
index 55836ce..9177a6b 100644
--- a/src/mirror-debugger.js
+++ b/src/mirror-debugger.js
@@ -2369,7 +2369,7 @@ function NumberToJSON_(value) {
   if (isNaN(value)) {
     return 'NaN';
   }
-  if (!isFinite(value)) {
+  if (!NUMBER_IS_FINITE(value)) {
     if (value > 0) {
       return 'Infinity';
     } else {
diff --git a/src/string.js b/src/string.js
index 9527599..ab0ab54 100644
--- a/src/string.js
+++ b/src/string.js
@@ -127,7 +127,7 @@ function StringLastIndexOf(pat /* position */) {  // length == 1
   var index = subLength - patLength;
   if (%_ArgumentsLength() > 1) {
     var position = ToNumber(%_Arguments(1));
-    if (!$isNaN(position)) {
+    if (!NUMBER_IS_NAN(position)) {
       position = TO_INTEGER(position);
       if (position < 0) {
         position = 0;
-- 
2.7.4