Make strict equality checks faster on IA32 by doing...

src/runtime.js

 // Copyright 2006-2008 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 76 matching lines @@
       x = %ToPrimitive(x, NO_HINT);
     }
   }
 }
 
 // ECMA-262, section 11.9.4, page 56.
 function STRICT_EQUALS(x) {
   if (IS_NUMBER(this)) {
     if (!IS_NUMBER(x)) return 1;  // not equal
     return %NumberEquals(this, x);
-  }
-
-  if (IS_STRING(this)) {
+  } else if (IS_STRING(this)) {

[bak, 2008/10/10 06:23:44]

What is up with excessive use of else parts.
return breaks the control flow.

     if (!IS_STRING(x)) return 1;  // not equal
     return %StringEquals(this, x);
+  } else if (IS_UNDEFINED(this)) {  
+    // Both undefined and undetectable.
+    return IS_UNDEFINED(x) ? 0 : 1;
+  } else {
+    // Objects, null, booleans and functions are all that's left.
+    // They can all be compared with a simple identity check.
+    return %_ObjectEquals(this, x) ? 0 : 1;
   }
-
-  if (IS_BOOLEAN(this)) {
-    if (!IS_BOOLEAN(x)) return 1;  // not equal
-    if (this) return x ? 0 : 1;
-    else return x ? 1 : 0;
-  }
-
-  if (IS_UNDEFINED(this)) {  // both undefined and undetectable
-    return IS_UNDEFINED(x) ? 0 : 1;
-  }
-
-  return %_ObjectEquals(this, x) ? 0 : 1;
 }
 
 
 // ECMA-262, section 11.8.5, page 53. The 'ncr' parameter is used as
 // the result when either (or both) the operands are NaN.
 function COMPARE(x, ncr) {
   // Fast case for numbers and strings.
   if (IS_NUMBER(this) && IS_NUMBER(x)) {
     return %NumberCompare(this, x, ncr);
   }
@@ skipping 393 matching lines @@
   throw %MakeTypeError('cannot_convert_to_primitive', []);
 }
 
 
 // NOTE: Setting the prototype for Array must take place as early as
 // possible due to code generation for array literals.  When
 // generating code for a array literal a boilerplate array is created
 // that is cloned when running the code.  It is essiential that the
 // boilerplate gets the right prototype.
 %FunctionSetPrototype($Array, new $Array(0));