Better codegen for '<expression> === void <literal>'.

src/full-codegen.cc

 // Copyright 2011 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 1272 matching lines @@
 
 
 int FullCodeGenerator::TryCatch::Exit(int stack_depth) {
   // The macros used here must preserve the result register.
   __ Drop(stack_depth);
   __ PopTryHandler();
   return 0;
 }
 
 
+bool FullCodeGenerator::TryLiteralCompare(Token::Value op,
+                                          Expression* left,
+                                          Expression* right,
+                                          Label* if_true,
+                                          Label* if_false,
+                                          Label* fall_through) {
+  if (op != Token::EQ && op != Token::EQ_STRICT) return false;
+
+  UnaryOperation* left_unary = left->AsUnaryOperation();
+  UnaryOperation* right_unary = right->AsUnaryOperation();  
+  Literal* left_literal = left->AsLiteral();  
+  Literal* right_literal = right->AsLiteral();
+  
+  // Check for the pattern: typeof <expression> == <string literal>.
+  if (left_unary != NULL && left_unary->op() == Token::TYPEOF &&
+      right_literal != NULL && right_literal->handle()->IsString()) {
+    EmitLiteralCompareTypeof(left_unary->expression(),
+                             Handle<String>::cast(right_literal->handle()),
+                             if_true, if_false, fall_through);
+    return true;
+  }
+
+  // Check for the pattern: <string literal> == typeof <expression>.
+  if (right_unary != NULL && right_unary->op() == Token::TYPEOF &&
+      left_literal != NULL && left_literal->handle()->IsString()) {
+    EmitLiteralCompareTypeof(right_unary->expression(),
+                             Handle<String>::cast(left_literal->handle()),
+                             if_true, if_false, fall_through);
+    return true;
+  }
+

[fschneider, 2011/06/21 11:36:08]

Remove extra line.

[Steven, 2011/06/22 10:00:53]

Done.

+  
+  if (op != Token::EQ_STRICT) return false;
+  
+  // Check for the pattern: <expression> === void <literal>.
+  if (right_unary != NULL && right_unary->op() == Token::VOID &&
+      right_unary->expression()->AsLiteral() != NULL) {
+    EmitLiteralCompareUndefined(left, if_true, if_false, fall_through);
+    return true;
+  }
+
+  // Check for the pattern: void <literal> === <expression>.
+  if (left_unary != NULL && left_unary->op() == Token::VOID &&
+      left_unary->expression()->AsLiteral() != NULL) {
+    EmitLiteralCompareUndefined(right, if_true, if_false, fall_through);
+    return true;
+  }
+  
+  return false;
+}
+
+
 #undef __
 
 
 } }  // namespace v8::internal