Improves performance for calls from Crankshaft code to certain string and...

src/string.js

 // Copyright 2012 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
@@ skipping 181 matching lines @@
     var result = %StringMatch(subject, regexp, lastMatchInfo);
     if (result !== null) lastMatchInfoOverride = null;
     return result;
   }
   // Non-regexp argument.
   regexp = new $RegExp(regexp);
   return RegExpExecNoTests(regexp, subject, 0);
 }
 
 
+function StringMatchNoResult(regexp) {
+  if (IS_NULL_OR_UNDEFINED(this) && !IS_UNDETECTABLE(this)) {
+    throw MakeTypeError("called_on_null_or_undefined",
+                        ["String.prototype.match"]);
+  }
+  var subject = TO_STRING_INLINE(this);
+  if (!IS_REGEXP(regexp))
+    regexp = new $RegExp(regexp);
+  if (!regexp.global) {
+    %_CallFunction(regexp, subject, RegExpExecNoResult);
+  } else {
+    regexp.lastIndex = 0;
+    var previousLastIndex = 0;
+    var lastMatch = true;
+    while (lastMatch) {
+      var result = %_CallFunction(regexp, subject, RegExpExecNoResult);
+      if (result == null)
+        lastMatch = false;
+      else {
+        var thisIndex = regexp.lastIndex;
+        if (thisIndex == previousLastIndex) {
+          regexp.lastIndex += 1;
+          previousLastIndex += 1;
+        } else {
+          previousLastIndex = thisIndex;
+        }
+      }
+    }
+  }
+}
+
 // SubString is an internal function that returns the sub string of 'string'.
 // If resulting string is of length 1, we use the one character cache
 // otherwise we call the runtime system.
 function SubString(string, start, end) {
   // Use the one character string cache.
   if (start + 1 == end) return %_StringCharAt(string, start);
   return %_SubString(string, start, end);
 }
 
 
@@ skipping 75 matching lines @@
     reusableMatchInfo[CAPTURE0] = start;
     reusableMatchInfo[CAPTURE1] = end;
     replace = TO_STRING_INLINE(replace);
     result = ExpandReplacement(replace, subject, reusableMatchInfo, result);
   }
 
   return result + SubString(subject, end, subject.length);
 }
 
 
+function StringReplaceNoResult(search, replace) {
+  if (IS_FUNCTION(replace)) {
+    // The function may have side effects, so we punt to the real method
+    return %_CallFunction(this, search, replace, StringReplace);
+  }
+
+  if (IS_NULL_OR_UNDEFINED(this) && !IS_UNDETECTABLE(this)) {
+    throw MakeTypeError("called_on_null_or_undefined",
+                        ["String.prototype.replace"]);
+  }
+
+  var subject = TO_STRING_INLINE(this);
+
+  if (IS_REGEXP(search)) {
+    %_CallFunction(subject, search, StringMatchNoResult);
+  } else {
+    TO_STRING_INLINE(search);
+  }
+  TO_STRING_INLINE(replace);
+}
+
+
 // Expand the $-expressions in the string and return a new string with
 // the result.
 function ExpandReplacement(string, subject, matchInfo, result) {
   var length = string.length;
   var next = %StringIndexOf(string, '$', 0);
   if (next < 0) {
     if (length > 0) result += string;
     return result;
   }
 
@@ skipping 340 matching lines @@
       }
       if (result.length === limit) break outer_loop;
     }
 
     startIndex = currentIndex = endIndex;
   }
   return result;
 }
 
 
+function StringSplitNoResult(separator, limit) {
+  if (IS_NULL_OR_UNDEFINED(this) && !IS_UNDETECTABLE(this)) {
+    throw MakeTypeError("called_on_null_or_undefined",
+                        ["String.prototype.split"]);
+  }
+  TO_STRING_INLINE(this);
+  limit = (IS_UNDEFINED(limit)) ? 0xffffffff : TO_UINT32(limit);
+  if (limit === 0) return;
+
+  // ECMA-262 says that if separator is undefined, the result should
+  // be an array of size 1 containing the entire string.  SpiderMonkey
+  // and KJS have this behavior only when no separator is given.  If
+  // undefined is explicitly given, they convert it to a string and
+  // use that.  We do as SpiderMonkey and KJS.
+  if (%_ArgumentsLength() === 0) {
+    return;
+  }
+
+  if (!IS_REGEXP(separator))
+    TO_STRING_INLINE(separator);
+}
+
+
 // ECMA-262 section 15.5.4.15
 function StringSubstring(start, end) {
   if (IS_NULL_OR_UNDEFINED(this) && !IS_UNDETECTABLE(this)) {
     throw MakeTypeError("called_on_null_or_undefined",
                         ["String.prototype.subString"]);
   }
   var s = TO_STRING_INLINE(this);
   var s_len = s.length;
 
   var start_i = TO_INTEGER(start);
@@ skipping 316 matching lines @@
     "fixed", StringFixed,
     "italics", StringItalics,
     "small", StringSmall,
     "strike", StringStrike,
     "sub", StringSub,
     "sup", StringSup
   ));
 }
 
 SetUpString();