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

src/string.js

Index: src/string.js
===================================================================
--- src/string.js	(revision 12582)
+++ src/string.js	(working copy)
@@ -199,6 +199,37 @@
 }
 
 
+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.
@@ -294,6 +325,28 @@
 }
 
 
+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) {
@@ -654,6 +707,29 @@
 }
 
 
+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)) {